Blocked polyisocyanate composition, resin composition, resin film and laminate

Abstract

To provide a blocked polyisocyanate composition that excels in storage stability, low-temperature curability, hardness, strength and solvent resistance and a resin composition, a resin film and a laminate each including the blocked polyisocyanate composition.SOLUTION: A blocked polyisocyanate composition includes a blocked polyisocyanate derived from polyisocyanate and at least one blocker, wherein the blocked polyisocyanate includes a constitutional unit represented by general formula (I) (R11-R13 independently represent an alkyl group optionally substituted with a hydroxy group and / or an amino group, the total number of carbon atoms of R11-R13 is 4-20, R14-R16 independently represent a hydrogen atom or an alkyl group optionally substituted with a hydroxy group and / or an amino group, and a wave line denotes a bond), and wherein the constitutional unit includes a constitutional unit (I-1) with R16 denoting a hydrogen atom.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a blocked polyisocyanate composition, a resin composition, a resin film, and a laminate. This application claims priority based on Japanese Patent Application No. 2020-085957, filed on May 15, 2020, and Japanese Patent Application No. 2020-189538, filed on November 13, 2020, the contents of which are incorporated herein by reference. [Background technology]

[0002] Traditionally, polyurethane resin paints have demonstrated excellent abrasion resistance, chemical resistance, and stain resistance. In particular, polyurethane resin paints using polyisocyanates derived from aliphatic or alicyclic diisocyanates have even better weather resistance, and demand for such paints is increasing. However, polyurethane resin paints are generally two-component, making their use extremely inconvenient. Conventional polyurethane resin paints consist of two components, a polyol and a polyisocyanate, which must be stored separately and then mixed before application. Furthermore, once mixed, the paint gels within a short time, rendering it unusable. These issues with polyurethane resin paints make their use in automated painting extremely difficult in fields involving line painting, such as automotive painting or low-voltage electropainting. Furthermore, because isocyanates readily react with water, their use with water-based paints, such as electrocoating, is impossible. Furthermore, when using paints containing isocyanates, thorough cleaning of the sprayer and coating tank is required after each application, significantly reducing work efficiency.

[0003] To overcome the above-mentioned problems, it has been proposed to use blocked polyisocyanates in which all active isocyanate groups are blocked with a blocking agent. This blocked polyisocyanate does not react with polyols at room temperature. However, heating dissociates the blocking agent, regenerating the active isocyanate groups, which then react with polyols to initiate a crosslinking reaction, thereby overcoming the above-mentioned problems. Therefore, many blocking agents have been investigated, and representative examples include phenol and methyl ethyl ketoxime.

[0004] However, when using blocked polyisocyanates using these blocking agents, a high baking temperature of 140° C. or higher is generally required. The need for baking at a high temperature is not only disadvantageous in terms of energy but also requires the substrate to be heat resistant, which limits its applications.

[0005] On the other hand, research has been conducted into low-temperature bake blocked polyisocyanates using active methylene compounds such as acetoacetic esters and malonic acid diesters. For example, Patent Documents 1 and 2 propose blocked polyisocyanate compositions that cure at 90°C. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-322238 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-335954 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in recent years, from the perspective of protecting the global environment and in light of strong demands for adaptability to plastics with low heat resistance, there has been a strong demand for blocked polyisocyanate compositions that cure at temperatures below 90° C. Under these circumstances, there is still no known composition that has good dispersibility in hydroxyl group-containing polyols (water-based polyols, water-dispersible polyols) when mixed, does not gel or excessively thicken during storage, does not decrease in curability after storage, has good curability at or below 90° C. or below 80° C., and produces coating films with excellent hardness and strength when cured at these temperatures.

[0008] The present invention has been made in view of the above circumstances, and provides a blocked polyisocyanate composition which, when made into a resin composition, has good storage stability, and, when made into a coating film, has excellent curability, hardness, strength, and solvent resistance at low temperatures of about 85°C or about 80°C, as well as a resin composition, a resin film, and a laminate which use the blocked polyisocyanate composition. [Means for solving the problem]

[0009] That is, the present invention includes the following aspects. (1) A blocked polyisocyanate composition comprising a blocked polyisocyanate derived from one or more diisocyanates, an active hydrogen compound, and a blocking agent containing a malonic acid ester, wherein the active hydrogen compound has a number average molecular weight of 60 or more and 5,000 or less, and an average number of functional groups of 1.6 or more and 2.4 or less. (2) A blocked polyisocyanate composition comprising a blocked polyisocyanate derived from an active hydrogen compound, a polyisocyanate, and a blocking agent containing a malonic acid ester, wherein the active hydrogen compound has a number average molecular weight of 60 or more and 5,000 or less and an average number of functional groups of 1.6 or more and 2.4 or less. (3) The blocked polyisocyanate composition according to (1) or (2), wherein the active hydrogen compound is polyol A. (4) The blocked polyisocyanate composition according to (3) above, wherein the polyol A is one or more polyols selected from the group consisting of 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanedimethanol, glycerol, and polycaprolactone polyols derived from any of these polyols and ε-caprolactone. (5) The blocked polyisocyanate composition according to any one of (2) to (4), wherein the content of the structural units derived from the active hydrogen compound is 0.05 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the structural units derived from the polyisocyanate. (6) The blocked polyisocyanate composition according to any one of (2) to (5), wherein the polyisocyanate has an average number of isocyanate groups of 3.5 or more, has an isocyanurate group, and is derived from one or more diisocyanates selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates. (7) The blocked polyisocyanate composition according to any one of (2) to (5), wherein the polyisocyanate is derived from a diisocyanate and a polyol B having an average functionality of 2.9 or more and 8.0 or less. (8) The blocked polyisocyanate composition according to any one of (2) to (7), wherein the blocked polyisocyanate contains a structural unit represented by general formula (I).

[0010] [ka]

[0011] In the general formula (I), R 11 , R 12 and R 13 are each independently an alkyl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group, and R 11 , R 12 and R 13 The total number of carbon atoms in R is 3 or more and 20 or less, 14 , R15 and R 16 are each independently a hydrogen atom or an alkyl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group, and the wavy line represents a bond. (9) In the general formula (I), R 11 , R 12 and R 13 The blocked polyisocyanate composition according to (8) above, wherein the total number of carbon atoms is 4 or more and 20 or less. (10) As the structural unit represented by the general formula (I), in the general formula (I), R 11 , R 12 and R 13 The total number of carbon atoms in R is 4 or more and 20 or less, 16 The blocked polyisocyanate composition according to (8) or (9) above, which contains a structural unit (I-1) in which represents a hydrogen atom. (11) As the structural unit represented by the general formula (I), in the general formula (I), R 11 , R 12 and R 13 are each independently an unsubstituted alkyl group, and R 14 , R 15 and R 16 and each independently contain a structural unit that is a hydrogen atom or an unsubstituted alkyl group. (12) The blocked polyisocyanate composition according to any one of (8) to (11), wherein the molar ratio of the hydroxy group contained in the polyol A to the structural unit represented by the general formula (I) is 0.5 / 99.5 to 15 / 85. (13) The blocked polyisocyanate composition according to any one of (1) to (12) above, wherein a part of the blocked polyisocyanate has a structural unit derived from a hydrophilic compound. (14) The blocked polyisocyanate composition according to (13) above, wherein the hydrophilic compound comprises one or more compounds selected from the group consisting of nonionic compounds and anionic compounds. (15) The blocked polyisocyanate composition according to any one of (1) to (14), wherein the blocking agent contains a malonic acid ester having a secondary alkyl group. (16) A blocked polyisocyanate composition comprising a blocked polyisocyanate derived from a polyisocyanate and one or more blocking agents, The blocked polyisocyanate is a blocked polyisocyanate composition containing a structural unit represented by general formula (I).

[0012] [ka]

[0013] In the general formula (I), R 11 , R 12 and R 13 are each independently an alkyl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group, and R 11 , R 12 and R 13 The total number of carbon atoms in R is 4 or more and 20 or less. 14 , R 15 and R 16 are each independently a hydrogen atom or an alkyl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group. A wavy line represents a bond. (17) The blocked polyisocyanate further contains a structural unit represented by general formula (II): The blocked polyisocyanate composition according to (16) above, wherein the molar ratio of the structural unit represented by general formula (II) to the structural unit represented by general formula (I) is 4 / 96 or more and 96 / 4 or less.

[0014] [ka]

[0015] In the general formula (II), R 21 , R 22 , R 23 and R24 are each independently a hydrogen atom or an alkyl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group. A wavy line represents a bond. (18) As the structural unit represented by the general formula (I), R 16 The blocked polyisocyanate composition according to (16) or (17) above, which contains a structural unit (I-1) in which represents a hydrogen atom. (19) In the general formula (I), R 11 , R 12 and R 13 are each independently a methyl group or an ethyl group. (20) The blocked polyisocyanate composition according to any one of (16) to (19) above, wherein a portion of the isocyanate groups of the polyisocyanate is modified with a nonionic compound. (21) The blocked polyisocyanate composition according to any one of (16) to (20) above, wherein the polyisocyanate has an average number of isocyanate groups of 2 or more. (22) The blocked polyisocyanate composition according to any one of (16) to (21), wherein the polyisocyanate is a polyisocyanate derived from one or more diisocyanates selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates. (23) The blocked polyisocyanate composition according to any one of (16) to (22), wherein the blocked polyisocyanate has an isocyanurate group. (24) A resin composition comprising the blocked polyisocyanate composition according to any one of (1) to (23) above and a polyvalent hydroxy compound. (25) A resin film obtained by curing the resin composition according to (24) above. (26) A laminate comprising two or more layers of the resin film according to (25) above, each having a different composition, The laminate has a thickness of 1 μm or more and 50 μm or less per layer. (27) A method for producing the blocked polyisocyanate composition according to any one of (1) to (15), comprising: a first step of reacting the polyisocyanate composition with a blocking agent containing a malonic acid ester; and a second step of reacting the blocked polyisocyanate composition obtained in the first step with an active hydrogen compound. [Effects of the Invention]

[0016] The blocked polyisocyanate composition of the above embodiment can provide a blocked polyisocyanate composition that has good storage stability when made into a resin composition and that, when made into a coating film, has excellent curability, hardness, and strength at low temperatures of about 80° C. or about 85° C. The resin composition of the above embodiment contains the blocked polyisocyanate composition and has good storage stability, and, when made into a coating film, has excellent curability, hardness, and strength at low temperatures of about 80° C. The resin film of the above embodiment is formed by curing the resin composition and has excellent curability, hardness, and strength at low temperatures of about 80° C. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail. Note that the present invention is not limited to the following embodiment. The present invention can be practiced with appropriate modifications within the scope of its gist.

[0018] In this specification, the term "polyol" refers to a compound having two or more hydroxy groups (-OH). As used herein, the term "polyisocyanate" refers to a reaction product in which a plurality of monomer compounds having one or more isocyanate groups (-NCO) are bonded together.

[0019] In this specification, the term "structural unit" refers to a structure derived from one molecule of a monomer in the structure constituting a polyisocyanate or a blocked polyisocyanate. For example, a structural unit derived from a malonic acid ester refers to a structure derived from one molecule of a malonic acid ester in a blocked polyisocyanate. The structural unit may be a unit formed directly by a (co)polymerization reaction of a monomer, or may be a unit in which a portion of the unit is converted into a different structure by treating the (co)polymer.

[0020] Blocked polyisocyanate composition of the first embodiment The blocked polyisocyanate composition of the first embodiment of the present invention comprises a blocked polyisocyanate derived from one or more diisocyanates, an active hydrogen compound, and a blocking agent containing a malonic acid ester.

[0021] [Diisocyanate] The diisocyanate is preferably one having 4 to 30 carbon atoms, and specific examples thereof include the following: These diisocyanates may be used alone or in combination of two or more. (1) Aromatic diisocyanates such as diphenylmethane-4,4'-diisocyanate (MDI), 1,5-naphthalene diisocyanate, tolylene diisocyanate (TDI), xylylene diisocyanate, and m-tetramethylxylylene diisocyanate (TMXDI). (2) Aliphatic diisocyanates such as 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (hereinafter sometimes referred to as "HDI"), 2,2,4-trimethyl-1,6-diisocyanatohexane, 2,4,4-trimethyl-1,6-hexamethylene diisocyanate, 2-methylpentane-1,5-diisocyanate (MPDI), and lysine diisocyanate (hereinafter sometimes referred to as "LDI"). (3) Alicyclic diisocyanates such as isophorone diisocyanate (hereinafter sometimes referred to as "IPDI"), 1,3-bis(diisocyanatemethyl)cyclohexane, 4,4'-dicyclohexylmethane diisocyanate, diisocyanate norbornane, and di(isocyanatemethyl)norbornane.

[0022] Among these, at least one selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates is preferably used. Furthermore, HDI or IPDI is more preferably used because of its industrial availability. Furthermore, HDI is even more preferably used because it allows the blocked polyisocyanate component to have a low viscosity. As the diisocyanate, it is preferable to use a combination of an aliphatic diisocyanate and an alicyclic diisocyanate, and it is particularly preferable to use HDI and IPDI. By using a combination of an aliphatic diisocyanate and an alicyclic diisocyanate, the toughness and hardness of the resulting coating film can be further improved.

[0023] When an aliphatic diisocyanate and an alicyclic diisocyanate are used in combination, the mass ratio of the structural units derived from the aliphatic diisocyanate to the structural units derived from the alicyclic diisocyanate is preferably 50 / 50 or more and 95 / 5 or less, more preferably 60 / 40 or more and 92 / 8 or less, and even more preferably 65 / 35 or more and 90 / 10 or less. When the mass ratio of the structural units derived from the aliphatic diisocyanate to the structural units derived from the alicyclic diisocyanate is equal to or greater than the above lower limit, a decrease in flexibility when formed into a coating film can be more effectively prevented, while when the mass ratio is equal to or less than the above upper limit, the hardness when formed into a coating film can be further improved.

[0024] The mass ratio of the constituent units derived from aliphatic diisocyanates to the constituent units derived from alicyclic diisocyanates can be calculated, for example, using the following method. First, the mass of the unreacted aliphatic diisocyanate and the mass of the unreacted alicyclic diisocyanate are calculated from the mass of the unreacted diisocyanate after the reaction and the aliphatic diisocyanate concentrations and alicyclic diisocyanate concentrations in this unreacted diisocyanate obtained by gas chromatographic measurement. Next, the calculated mass of the unreacted aliphatic diisocyanate and the unreacted alicyclic diisocyanate are subtracted from the mass of the charged aliphatic diisocyanate and the mass of the alicyclic diisocyanate, respectively, and the obtained differences are taken as the masses of the constituent units derived from aliphatic diisocyanates and the masses of the constituent units derived from alicyclic diisocyanates, respectively. Next, the mass ratio of the aliphatic diisocyanate-derived structural units to the alicyclic diisocyanate-derived structural units is obtained by dividing the mass of the aliphatic diisocyanate-derived structural units by the mass of the alicyclic diisocyanate-derived structural units.

[0025] [Active hydrogen compounds] The active hydrogen compound of this embodiment is a compound containing a hydroxyl group and / or an amino group as an active hydrogen group. The number average molecular weight Mn of the active hydrogen compound is from 60 to 5000, preferably from 100 to 4700, more preferably from 300 to 4500, and even more preferably from 500 to 4000. When the number average molecular weight Mn of the active hydrogen compound is within the above range, the resulting coating film has excellent curability and strength at low temperatures of around 80°C. The number average molecular weight Mn of the active hydrogen compound is, for example, the number average molecular weight measured by gel permeation chromatography (GPC) using polystyrene standards. Specifically, it can be measured using the method described in the examples below.

[0026] The average number of functional groups of the active hydrogen compound is from 1.6 to 2.4, preferably from 1.8 to 2.2, and more preferably from 1.9 to 2.1. When the average number of functional groups of the active hydrogen compound is within the above range, high curability can be achieved while suppressing gelation during synthesis of the blocked polyisocyanate and gelation during storage. The average number of functional groups in an active hydrogen compound can be calculated using the following formula: In the formula, "Mn" represents the number average molecular weight of the active hydrogen compound, "hydroxyl group content" represents the content (mass%) of hydroxyl groups relative to 100% mass of the solid content of the active hydrogen compound, "17" represents the molecular weight (g / mol) of hydroxyl groups, "amino group content" represents the content (mass%) of amino groups relative to 100% mass of the active hydrogen compound, and "15" represents the molecular weight (g / mol) of amino groups. (Average number of functional groups of active hydrogen compounds) = {(Mn of active hydrogen compounds) × (hydroxyl group content) × 0.01} / 17 + {(Mn of active hydrogen compounds) × (amino group content) × 0.01} / 15

[0027] The content of the constituent units derived from the active hydrogen compound relative to 100 parts by mass of the constituent units derived from the diisocyanate is preferably 0.05 parts by mass to 10 parts by mass, more preferably 0.1 parts by mass to 9 parts by mass, even more preferably 0.25 parts by mass to 8 parts by mass, and even more preferably 0.3 parts by mass to 7 parts by mass, or more preferably 0.6 parts by mass to 9.5 parts by mass relative to 100 parts by mass of the constituent units derived from the diisocyanate. When the content of the constituent units derived from the active hydrogen compound relative to 100 parts by mass of the constituent units derived from the diisocyanate is at least the above lower limit, the resulting coating tends to have excellent curability, hardness, and strength at a low temperature of about 80° C. On the other hand, when the content of the constituent units derived from the active hydrogen compound relative to 100 parts by mass of the constituent units derived from the diisocyanate is at most the above upper limit, gelation during synthesis of the blocked polyisocyanate composition can be suppressed, and the resulting resin composition can have good storage stability.

[0028] The content of the constituent units derived from the active hydrogen compound relative to 100 parts by mass of the constituent units derived from the diisocyanate can be calculated, for example, from the blending ratio of the raw materials. Alternatively, the content of the constituent units derived from the active hydrogen compound relative to 100 parts by mass of the constituent units derived from the diisocyanate can also be determined, for example, by nuclear magnetic resonance (NMR), infrared absorption spectroscopy (IR), gas chromatography (GC), mass spectrometry (MS), etc.

[0029] The active hydrogen compound containing an amino group is not particularly limited, but examples thereof include aliphatic diamine compounds such as ethylenediamine, trimethylenediamine, hexamethylenediamine, and octamethylenediamine; aromatic diamine compounds such as phenylenediamine and 4,4'-methylenebis(phenylamine); alicyclic diamine compounds such as cyclopentyldiamine, cyclohexyldiamine, 4,4'-diaminodicyclohexylmethane, 1,4-diaminocyclohexane, and isophoronediamine; and aspartic acid ester compounds.

[0030] The active hydrogen compound containing an amino group and a hydroxyl group is not particularly limited, but examples thereof include 1-amino-2-propanol and 5-amino-1-pentanol.

[0031] [Polyol A] The active hydrogen compound of this embodiment preferably contains only hydroxyl groups (hereinafter referred to as polyol A). The number average molecular weight Mn of polyol A is 60 or more and 5000 or less, preferably 100 or more and 4700 or less, more preferably 300 or more and 4500 or less, and even more preferably 500 or more and 4000 or less. When the number average molecular weight Mn of polyol A is within the above range, the resulting coating film has excellent curability and strength at low temperatures of about 80°C. The number average molecular weight Mn of polyol A is, for example, the number average molecular weight measured by gel permeation chromatography (GPC) using polystyrene standards. Specifically, it can be measured using the method described in the Examples below.

[0032] The average number of functional groups of polyol A is 1.6 or more and 2.4 or less, preferably 1.8 or more and 2.2 or less, and more preferably 1.9 or more and 2.1 or less. When the average number of functional groups of polyol A is within the above range, high curability can be achieved while suppressing gelation during synthesis of the blocked polyisocyanate and gelation during storage. The average number of functional groups of polyol A can be calculated using the following formula. In the formula, "Mn" represents the number average molecular weight of polyol A, "hydroxyl group content" represents the content (mass%) of hydroxyl groups relative to 100 mass% solids content of polyol A, and "17" represents the molecular weight (g / mol) of the hydroxyl groups. (Average number of functional groups of polyol A) = {(Mn of polyol A) × (hydroxyl group content) × 0.01} / 17

[0033] Examples of polyol A include 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanedimethanol, glycerol, polycaprolactone polyols derived from any of these and ε-caprolactone, and one or more polyols selected from the group consisting of polyether polyols, polycarbonate polyols, and acrylic polyols. Among these, one or more diols selected from the group consisting of 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanedimethanol, and glycerol, or polycaprolactone diols derived from these diols and ε-caprolactone are preferred, and one or more diols selected from the group consisting of 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, and 1,4-cyclohexanedimethanol, or polycaprolactone diols derived from these diols and ε-caprolactone are more preferred. Commercially available polycaprolactone diols include, for example, Daicel Corporation's "Placcel 205UT" (number average molecular weight 530), "Placcel 220CPT" (number average molecular weight 2000), and "Placcel 240CP" (number average molecular weight 4000).

[0034] [Blocking agent] The blocking agent includes a malonic acid ester. The malonic acid ester is not particularly limited, but preferably includes a malonic acid ester having a secondary alkyl group or a malonic acid ester having a primary alkyl group, and a malonic acid ester having a tertiary alkyl group, and more preferably includes a malonic acid ester having a secondary alkyl group and a malonic acid ester having a tertiary alkyl group. The blocking agent may include one type of each of a malonic acid ester having a secondary alkyl group, a malonic acid ester having a primary alkyl group, and a malonic acid ester having a tertiary alkyl group, or may include a combination of two or more types.

[0035] The malonic acid ester having a primary alkyl group is not particularly limited, and examples thereof include dimethyl malonate, diethyl malonate, dipropyl malonate, dibutyl malonate, dicyclohexyl malonate, diphenyl malonate, etc. Among these, diethyl malonate is preferred as the malonic acid ester having a primary alkyl group.

[0036] The malonic acid ester having a secondary alkyl group is not particularly limited, and examples thereof include di-sec-butyl malonate, diisopropyl malonate, isopropylethyl malonate, etc. Among these, diisopropyl malonate is preferred as the malonic acid ester having a secondary alkyl group.

[0037] Malonic acid esters having a tertiary alkyl group are not particularly limited, and examples thereof include di-tert-butyl malonate, di(2-methyl-2-butyl) malonate, di(2-methyl-2-pentyl) malonate, (tert-butyl)ethyl malonate, (2-methyl-2-butyl)ethyl malonate, (2-methyl-2-butyl)isopropyl malonate, (2-methyl-2-pentyl)ethyl malonate, (2-methyl-2-pentyl)isopropyl malonate, and (2-methyl-2-pentyl)hexylisopropyl malonate. Among these, di(2-methyl-2-butyl) malonate, di(2-methyl-2-pentyl) malonate, (2-methyl-2-butyl) isopropyl malonate, (2-methyl-2-pentyl) ethyl malonate, and (2-methyl-2-pentyl) isopropyl malonate are preferred, and (2-methyl-2-butyl) ethyl malonate, (2-methyl-2-butyl) isopropyl malonate, (2-methyl-2-pentyl) ethyl malonate, and (2-methyl-2-pentyl) hexyl isopropyl malonate are preferred, or di-tert-butyl malonate, (2-methyl-2-butyl) isopropyl malonate, or (2-methyl-2-pentyl) isopropyl malonate are preferred. The malonic acid ester having a tertiary alkyl group may be a commercially available product, or may be synthesized by the method described in Reference Document 1 (JP-A-11-130728).

[0038] Based on the total molar amount of all blocking agents used in the production of the blocked polyisocyanate, the content of the malonic acid ester having a secondary alkyl group and the malonic acid ester having a tertiary alkyl group is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, particularly preferably 95 mol% or more, and most preferably 100 mol%. When the content of the malonic acid ester having a secondary alkyl group and the malonic acid ester having a tertiary alkyl group is within the above range, the low-temperature curing property of the resin film can be further improved.

[0039] (Other blocking agents) The blocking agent used in the production of the blocked polyisocyanate may further contain other blocking agents in addition to the malonic acid ester having a secondary alkyl group and the malonic acid ester having a tertiary alkyl group, as long as the other blocking agents do not impair the storage stability of the resin composition formed therefrom or the low-temperature curing properties of the resin film formed therefrom.

[0040] Examples of other blocking agents include 1) alcohol-based compounds, 2) alkylphenol-based compounds, 3) phenol-based compounds, 4) active methylene-based compounds other than malonic acid esters having a secondary alkyl group and malonic acid esters having a tertiary alkyl group, 5) mercaptan-based compounds, 6) acid amide-based compounds, 7) acid imide-based compounds, 8) imidazole-based compounds, 9) urea-based compounds, 10) oxime-based compounds, 11) amine-based compounds, 12) imide-based compounds, 13) bisulfites, 14) pyrazole-based compounds, 15) triazole-based compounds, etc. More specific examples of blocking agents include the following:

[0041] 1) Alcohol compounds: alcohols such as methanol, ethanol, 2-propanol, n-butanol, sec-butanol, 2-ethyl-1-hexanol, 2-methoxyethanol, 2-ethoxyethanol, and 2-butoxyethanol. 2) Alkylphenol compounds: mono- and di-alkylphenols having an alkyl group having 4 or more carbon atoms as a substituent. Specific examples of the alkylphenol compounds include mono-alkylphenols such as n-propylphenol, iso-propylphenol, n-butylphenol, sec-butylphenol, tert-butylphenol, n-hexylphenol, 2-ethylhexylphenol, n-octylphenol, and n-nonylphenol; and di-n-propylphenol, diisopropylphenol, isopropyl cresol, di-n-butylphenol, di-tert-butylphenol, di-sec-butylphenol, di-n-octylphenol, di-2-ethylhexylphenol, and di-n-nonylphenol.

[0042] 3) Phenolic compounds: phenol, cresol, ethylphenol, styrenated phenol, hydroxybenzoic acid esters, etc. 4) Active methylene compounds: dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate, methyl isobutanoylacetate, ethyl isobutanoylacetate, acetylacetone, etc. 5) Mercaptan compounds: butyl mercaptan, dodecyl mercaptan, etc. 6) Acid amide compounds: acetanilide, acetic acid amide, ε-caprolactam, δ-valerolactam, γ-butyrolactam, etc. 7) Acid imide compounds: succinimide, maleimide, etc. 8) Imidazole compounds: imidazole, 2-methylimidazole, etc. 9) Urea compounds: urea, thiourea, ethyleneurea, etc.

[0043] 10) Oxime compounds: formaldoxime, acetaldoxime, acetoxime, methyl ethyl ketoxime, cyclohexanone oxime, etc. 11) Amine compounds: diphenylamine, aniline, carbazole, di-n-propylamine, diisopropylamine, isopropylethylamine, etc. 12) Imine compounds: ethyleneimine, polyethyleneimine, etc. 13) Bisulfite compounds: sodium bisulfite, etc. 14) Pyrazole compounds: pyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole, etc. 15) Triazole compounds: 3,5-dimethyl-1,2,4-triazole, etc.

[0044] (Other components) The blocked polyisocyanate composition of the present embodiment may further contain additives such as a solvent in addition to the blocked polyisocyanate.

[0045] Examples of the solvent include 1-methylpyrrolidone, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether, 3-methoxy-3-methyl-1-butanol, ethylene glycol diethyl ether, diethylene glycol diethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether (DPDM), propylene glycol dimethyl ether, methyl ethyl ketone, and acetonitrile. Examples of suitable solvents include ethanol, methyl isobutyl ketone, propylene glycol monomethyl ether acetate, ethanol, methanol, isopropanol, 1-propanol, isobutanol, 1-butanol, tert-butanol, 2-ethylhexanol, cyclohexanol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, ethyl acetate, isopropyl acetate, butyl acetate, toluene, xylene, pentane, isopentane, hexane, isohexane, cyclohexane, solvent naphtha, and mineral spirits. These solvents may be used alone or in combination of two or more. From the viewpoint of dispersibility in water, the solvent preferably has a solubility in water of 5% by mass or more, and specifically, DPDM is preferred.

[0046] <Method for producing the blocked polyisocyanate composition of the first embodiment> The blocked polyisocyanate composition of the first embodiment is not particularly limited, and can be obtained, for example, by reacting the diisocyanate, the active hydrogen compound, and the blocking agent. The blocked polyisocyanate composition may be produced by simultaneously reacting these compounds. The blocked polyisocyanate composition may be produced by reacting the diisocyanate with the active hydrogen compound to produce an active hydrogen compound-modified polyisocyanate, and then reacting the active hydrogen compound-modified polyisocyanate with a blocking agent. Alternatively, the blocked polyisocyanate composition may be produced by reacting the diisocyanate with the blocking agent to produce a partially blocked polyisocyanate in which some or all of the isocyanate groups of the polyisocyanate are blocked with a blocking agent, and then reacting the partially blocked polyisocyanate with the active hydrogen compound.

[0047] The modification reaction between the diisocyanate and the active hydrogen compound can be carried out in the presence or absence of a solvent. The amount of the active hydrogen compound added is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 9 parts by mass, more preferably 0.25 to 8 parts by mass, and even more preferably 0.3 to 7 parts by mass, per 100 parts by mass of the diisocyanate. Alternatively, the amount of the active hydrogen compound-derived structural units added per 100 parts by mass of the diisocyanate-derived structural units is more preferably 0.6 to 9.5 parts by mass. When the amount of the active hydrogen compound added is equal to or greater than the lower limit, the resulting coating tends to exhibit excellent curability, hardness, and strength at low temperatures around 80°C. On the other hand, when the amount of the active hydrogen compound added is equal to or less than the upper limit, gelation during synthesis of the blocked polyisocyanate composition can be suppressed, and the resulting resin composition can exhibit excellent storage stability.

[0048] When a solvent is used during the modification reaction between the diisocyanate and the active hydrogen compound, the solvent may be inactive to the isocyanate group. The active hydrogen compound-modified polyisocyanate preferably contains an isocyanurate group, an allophanate group, a urethane group and / or a urea group.

[0049] Examples of the modification reaction between diisocyanate and active hydrogen compound will be described below, but are not limited to the following. First, the isocyanate groups of the diisocyanate and the active hydrogen groups of the active hydrogen compound are converted into urethane and / or urea. The reaction temperature can be set to 20 to 200°C. The reaction temperature is preferably 50 to 150°C, more preferably 50 to 120°C, and even more preferably 50 to 100°C. If the temperature is 50°C or higher, the reaction tends to proceed more easily, while if the temperature is 200°C or lower, the resulting polyisocyanate composition tends to be less colored. The reaction time is preferably in the range of 0.5 to 24 hours, more preferably 0.5 to 10 hours, and even more preferably 0.5 to 5 hours.

[0050] After a part or all of the active hydrogen groups of the active hydrogen compound react with the isocyanate groups of the diisocyanate, an isocyanurate-forming and allophanate-forming reaction is carried out. The urethanization reaction may be carried out after the allophanate reaction or the isocyanurate reaction, or may be carried out simultaneously with the allophanate reaction or the isocyanurate reaction, but it is preferred to form a urethane bond by the reaction of the isocyanate group of the diisocyanate with the hydroxyl group of the active hydrogen compound, and then carry out the allophanate reaction simultaneously with the isocyanurate reaction. These reactions can be appropriately carried out by selecting an isocyanurate reaction catalyst and reaction conditions.

[0051] When the reaction is carried out using a catalyst, the reaction temperature for isocyanuration and allophanation is 60 to 160°C, preferably 70 to 100°C. When the reaction temperature is 60°C or higher, the allophanate reaction proceeds more easily, and the molar ratio of allophanate groups / (allophanate groups + urethane groups) tends to be higher. When the reaction temperature is 160°C or lower, the resulting polyisocyanate composition tends to be less colored.

[0052] The reaction time for isocyanuration and allophanation is preferably 1 to 10 hours, more preferably 1 to 7 hours, and even more preferably 1 to 5 hours. When the reaction time is 1 hour or longer, the isocyanuration rate and allophanation rate tend to be high. When the reaction time is 10 hours or shorter, coloration tends to be less.

[0053] The isocyanuration and allophanatization catalysts that can be used in the above are not particularly limited, but are preferably basic. Examples include, but are not limited to, (i) hydroxides of tetraalkylammonium (e.g., tetramethylammonium, tetraethylammonium), and organic weak acid salts (e.g., acetic acid, capric acid), (ii) hydroxides of hydroxyalkylammonium (e.g., trimethylhydroxypropylammonium, trimethylhydroxyethylammonium, triethylhydroxypropylammonium, triethylhydroxyethylammonium), and organic weak acid salts (e.g., acetic acid, caproic acid, octylic acid, myristic acid), (iii) alkali metal salts (e.g., tin, zinc, lead) of alkylcarboxylic acids (e.g., acetic acid, caproic acid, octylic acid, myristic acid), (iv) metal alcoholates (e.g., sodium, potassium), (v) aminosilyl group-containing compounds (e.g., hexamethyldisilazane), (vi) Mannich bases, (vii) combinations of tertiary amines and epoxy compounds, and (viii) phosphorus-based compounds (e.g., tributylphosphine). Among these, preferred are hydroxides of tetraalkylammonium and organic weak acid salts. These catalysts may be added either all at once or continuously.

[0054] To terminate these reactions, the catalyst is deactivated. To neutralize and deactivate the catalyst, an acidic substance such as phosphoric acid or an acidic phosphate ester is added. The catalyst can also be deactivated by thermal decomposition or chemical decomposition. Furthermore, the catalyst can also be deactivated by adsorbing it onto activated carbon, alumina, or the like and removing it from the system. The yield of the polyisocyanate composition ((mass of the obtained polyisocyanate composition / total mass of the charged raw materials) × 100) is preferably 10 to 70 mass%, more preferably 30 to 60 mass%. By increasing this yield, the molar ratio of isocyanate groups to allophanate groups and urethane groups can be increased, and by decreasing this yield, the molar ratio of isocyanate groups to allophanate groups and urethane groups can be decreased.

[0055] After the reaction is complete, the unreacted diisocyanate monomer is removed using a thin film evaporator, extraction, or the like. The concentration of the unreacted diisocyanate monomer in the resulting polyisocyanate composition is preferably 3% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, and even more preferably 0.3% by mass or less. When the concentration of the unreacted diisocyanate monomer is 3% by mass or less, curability tends to be better. At least a portion of the active hydrogen compound-modified polyisocyanate may have a structural unit derived from a hydrophilic compound, i.e., a hydrophilic group.

[0056] The blocking reaction between the diisocyanate (or the active hydrogen compound-modified polyisocyanate) and the blocking agent is not particularly limited, but examples thereof include the following two methods. 1) A method of reacting the above diisocyanate (or active hydrogen compound-modified polyisocyanate) with the above malonic acid ester having a tertiary alkyl group, and the above malonic acid ester having a secondary alkyl group or the above malonic acid ester having a primary alkyl group. 2) A method in which the diisocyanate (or active hydrogen compound-modified polyisocyanate) is reacted with at least one blocking agent selected from the group consisting of the malonic acid ester having a tertiary alkyl group, the malonic acid ester having a secondary alkyl group, and the malonic acid ester having a primary alkyl group, and an alcohol having a chain alkyl group is added to the resulting reaction product to introduce an alkyl group derived from the alcohol by transesterification of the terminal ester moiety of the reaction product.

[0057] The blocking reaction between a diisocyanate (or an active hydrogen compound-modified polyisocyanate) and a blocking agent can be carried out regardless of the presence or absence of a solvent. The blocking agent may be a malonic acid ester having a primary alkyl group, a malonic acid ester having a secondary alkyl group, or a malonic acid ester having a tertiary alkyl group, each of which may be used alone or in combination of two or more. The amount of the blocking agent added may usually be 80 mol % or more and 200 mol % or less, and preferably 90 mol % or more and 150 mol % or less, based on the total molar amount of isocyanate groups.

[0058] Furthermore, when a malonic acid ester having a secondary alkyl group and a malonic acid ester having a tertiary alkyl group are used in the blocking agent to be added, the molar ratio of the malonic acid ester having a secondary alkyl group to the malonic acid ester having a tertiary alkyl group (malonic acid ester having a secondary alkyl group / malonic acid ester having a tertiary alkyl group) is preferably more than 5 / 95 and less than 95 / 5, more preferably 7 / 93 or more and 93 / 7 or less, even more preferably 10 / 90 or more and 93 / 7 or less, even more preferably 20 / 80 or more and 93 / 7 or less, and particularly preferably 30 / 70 or more and 93 / 7 or less. When the molar ratio is equal to or greater than the lower limit, the storage stability of the resin composition can be improved, and when the molar ratio is equal to or less than the upper limit, the low-temperature curing properties of the resin film can be improved.

[0059] When a solvent is used during the blocking reaction, it is sufficient to use a solvent that is inactive to isocyanate groups. When a solvent is used, the content of the nonvolatile components per 100 parts by mass of the blocked polyisocyanate composition may usually be 10 parts by mass or more and 95 parts by mass or less, preferably 20 parts by mass or more and 80 parts by mass or less, and more preferably 30 parts by mass or more and 75 parts by mass or less.

[0060] In the blocking reaction, organic metal salts of tin, zinc, lead, etc., tertiary amine compounds, alcoholates of alkali metals such as sodium, etc., may be used as catalysts. The amount of catalyst added varies depending on the temperature of the blocking reaction, etc., but is usually from 0.05 to 1.5 parts by mass, preferably from 0.1 to 1.0 part by mass, per 100 parts by mass of polyisocyanate.

[0061] The blocking reaction can generally be carried out at a temperature of −20° C. or higher and 150° C. or lower, preferably at a temperature of 0° C. or higher and 100° C. or lower, and more preferably at a temperature of 10° C. or higher and 80° C. When the temperature of the blocking reaction is equal to or higher than the lower limit, the reaction rate can be increased, and when the temperature is equal to or lower than the upper limit, side reactions can be suppressed.

[0062] After the blocking reaction, a neutralization treatment may be carried out by adding an acidic compound or the like. The acidic compound may be an inorganic acid or an organic acid. Examples of inorganic acids include hydrochloric acid, phosphorous acid, and phosphoric acid. Examples of organic acids include methanesulfonic acid, p-toluenesulfonic acid, dioctyl phthalate, and dibutyl phthalate.

[0063] When the polyisocyanate is produced by the above method 2), the blocking reaction is followed by an ester exchange reaction. The alcohol having a chain alkyl group used in the transesterification reaction of method 2) is preferably a monoalcohol, and examples thereof include primary monoalcohols such as methanol, ethanol, propanol, butanol, hexanol, and 2-ethylhexanol; secondary monoalcohols such as isopropanol, 2-butanol, 2-pentanol, and 2-hexanol; and tertiary monoalcohols such as tert-butanol, 2-methyl-2-butanol, 2-methyl-2-pentanol, 2-methyl-2-hexanol, 2-methyl-2-heptanol, 2-methyl-2-octanol, 3-methyl-3-pentanol, 3-ethyl-3-hexanol, and 3-ethyl-3-octanol. The chain alkyl group of the alcohol may be the same as or different from that of the blocking agent. When the chain alkyl group is different from that of the blocking agent, it is preferable to use a monoalcohol having a chain alkyl group with a different number of alkyl substitutions than that of the blocking agent. Specifically, for example, when a single malonic acid ester having a secondary alkyl group is used as the blocking agent, a monoalcohol having a tertiary alkyl group can be used.

[0064] In the case of producing by the method 2), it is preferable to remove the generated alcohol or the residual added alcohol during or after the transesterification reaction by distillation under normal pressure or reduced pressure. Among these, in order to efficiently proceed with the transesterification reaction, it is preferable to remove the generated alcohol by performing an operation such as distillation during the transesterification reaction. In this case, in order to efficiently remove the alcohol component generated by the transesterification reaction, it is more preferable that the alcohol component to be added has a boiling point higher than that of the generated alcohol component. The transesterification reaction can generally be carried out at a temperature of 0° C. or higher and 150° C. or lower, preferably 30° C. or higher and 120° C. or lower, and more preferably 50° C. or higher and 100° C. When the temperature of the transesterification reaction is equal to or higher than the lower limit, the reaction rate can be further increased, and when the temperature is equal to or lower than the upper limit, side reactions can be further suppressed.

[0065] The amount of the alcohol component in the blocked polyisocyanate composition is preferably 0.05 to 41 parts by mass, more preferably 0.1 to 30 parts by mass, and even more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the solids content of the blocked polyisocyanate composition. When the amount of the alcohol component is at least the above lower limit, the storage stability of the paint is improved, and when it is at most the above upper limit, thickening of the aqueous paint during formulation can be suppressed.

[0066] Blocked polyisocyanate composition of the second embodiment The blocked polyisocyanate composition according to the second embodiment of the present invention comprises a blocked polyisocyanate derived from an active hydrogen compound, a polyisocyanate, and a blocking agent containing a malonic acid ester. Description of the same configuration as in the first embodiment may be omitted.

[0067] The polyisocyanate preferably has an isocyanurate group and is derived from one or more diisocyanates selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates.

[0068] The average number of isocyanate groups in the polyisocyanate is 3.5 or more, preferably 4.0 or more, more preferably 4.5 or more, and even more preferably 4.7 or more. When the average number of isocyanate groups in the polyisocyanate is equal to or greater than the above-mentioned lower limit, the resulting coating film has excellent curability, hardness, and strength at low temperatures of about 80°C. On the other hand, the upper limit of the average number of isocyanate groups in the polyisocyanate is not limited and can be, for example, 20, 10, or 8. The average number of isocyanate groups in a polyisocyanate can be calculated, for example, from the number average molecular weight Mn and the isocyanate group content (NCO content) of the polyisocyanate using the following formula: Average number of isocyanate groups = (Mn of polyisocyanate × NCO content × 0.01) / 42

[0069] The number average molecular weight Mn of the polyisocyanate is, for example, the number average molecular weight measured by GPC using polystyrene standards. Specifically, it can be measured using the method described in the examples below.

[0070] The isocyanate group content (NCO content) can be measured, for example, by the following method. Accurately weigh out 2 g to 3 g of polyisocyanate into a flask (W g). Next, add 20 mL of toluene to dissolve the polyisocyanate. Next, add 20 mL of a 2 N toluene solution of di-n-butylamine, mix, and leave at room temperature for 15 minutes. Next, add 70 mL of isopropyl alcohol and mix. Next, titrate this liquid with 1 N hydrochloric acid solution (factor F) using the indicator. The titration value obtained is V2 mL. Next, the titration value obtained without polyisocyanate is V1 mL. Next, calculate the isocyanate group (NCO) content (mass%) of the polyisocyanate using the following formula: Isocyanate group (NCO) content (mass%) = (V1 - V2) x F x 42 / (W x 1000) x 100

[0071] Alternatively, the polyisocyanate is preferably one derived from the diisocyanate and a polyol B having an average functionality of 2.9 to 8.0. This allows the average number of isocyanate groups in the resulting polyisocyanate to be increased. In the polyisocyanate, urethane groups are formed by the reaction between the hydroxyl groups of the polyol B and the isocyanate groups of the diisocyanate.

[0072] The average number of functional groups of polyol B is preferably 2.9 or more and 8.0 or less, more preferably 3 or more and 8 or less, more preferably 3 or more and 6 or less, even more preferably 3 or more and 5 or less, and particularly preferably 3 or 4. The average number of functional groups of polyol B can be calculated, for example, using the following formula: In the formula, "Mn" represents the number average molecular weight of polyol B, "hydroxyl group content" represents the content (mass%) of hydroxyl groups relative to 100 mass% of the solid content of polyol B, and "17" represents the molecular weight (g / mol) of the hydroxyl groups. (Average number of functional groups of polyol B)={(Mn of polyol B)×(hydroxyl group content)×0.01} / 17

[0073] The number average molecular weight Mn of polyol B is preferably 100 or more and 1,000 or less, preferably 100 or more and 900 or less, more preferably 100 or more and 800 or less, even more preferably 100 or more and 700 or less, even more preferably 100 or more and 500 or less, still more preferably 100 or more and 400 or less, and particularly preferably 100 or more and 350 or less. When the number-average molecular weight Mn of the polyol is within the above range, the blocked polyisocyanate composition has excellent low-temperature curing properties when formed into a coating film, and also has excellent hardness and strength. The number-average molecular weight Mn of the polyol B is, for example, the number-average molecular weight measured by GPC using polystyrene as the standard.

[0074] The content of the structural units derived from the active hydrogen compound relative to 100 parts by mass of the structural units derived from the polyisocyanate is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 9 parts by mass, even more preferably 0.25 to 8 parts by mass, and even more preferably 0.3 to 7 parts by mass. When the content of the structural units derived from the active hydrogen compound relative to 100 parts by mass of the structural units derived from the polyisocyanate is equal to or greater than the above-mentioned lower limit, the resulting coating tends to exhibit excellent curability, hardness, and strength at low temperatures of around 80°C. On the other hand, when the content of the structural units derived from the active hydrogen compound relative to 100 parts by mass of the structural units derived from the polyisocyanate is equal to or less than the above-mentioned upper limit, gelation during synthesis of the blocked polyisocyanate composition can be suppressed, and the resulting resin composition can exhibit excellent storage stability. The content of the constituent units derived from the active hydrogen compound relative to 100 parts by mass of the constituent units derived from the polyisocyanate can be calculated, for example, from the blending ratio of raw materials. Alternatively, the content of the constituent units derived from the active hydrogen compound relative to 100 parts by mass of the constituent units derived from the polyisocyanate can also be determined, for example, by nuclear magnetic resonance (NMR), infrared absorption spectroscopy (IR), gas chromatography (GC), mass spectrometry (MS), etc.

[0075] By using a malonic acid ester as a blocking agent, the blocked polyisocyanate composition of this embodiment can achieve both good storage stability when made into a resin composition and excellent curability at a low temperature of about 80° C. when made into a coating film. Furthermore, by modifying some of the isocyanate groups of the blocked polyisocyanate with an active hydrogen compound, it is possible to improve the storage stability when made into a resin composition and the curability at a low temperature of about 80° C. when made into a coating film, and the hardness and strength of the coating film can be improved.

[0076] Each of the constituent components contained in the blocked polyisocyanate composition of the present embodiment will be described in more detail below.

[0077] <Blocked polyisocyanate> A blocked polyisocyanate is a reaction product of an active hydrogen compound, a polyisocyanate, and a blocking agent, i.e., in the blocked polyisocyanate, at least some of the isocyanate groups in the polyisocyanate are modified with an active hydrogen compound and at least some of the isocyanate groups in the polyisocyanate are blocked with a blocking agent.

[0078] Unit The blocked polyisocyanate preferably contains a structural unit represented by the following general formula (I) (hereinafter, sometimes referred to as structural unit (I)).

[0079] [ka]

[0080] In the general formula (I), R 11 , R 12 and R 13 are each independently an alkyl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group, and R 11 , R 12 and R 13 The total number of carbon atoms in R is 3 or more and 20 or less,14 , R 15 and R 16 are each independently a hydrogen atom or an alkyl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group, and the wavy line represents the bonding site with the residue of the polyisocyanate excluding the isocyanate group.

[0081] R 11 , R 12 , R 13 , R 14 , R 15 and R 16 The alkyl group in the formula (I) preferably has 1 to 20 carbon atoms, more preferably 1 to 8 carbon atoms, further preferably 1 to 6 carbon atoms, and particularly preferably 1 to 4 carbon atoms.

[0082] Specific examples of the unsubstituted alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a tert-butyl group, a sec-butyl group, an isobutyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, a 1-methylbutyl group, an n-hexyl group, a 2-methylpentyl group, a 3-methylpentyl group, a 2,2-dimethylbutyl group, a 2,3-dimethylbutyl group, an n-heptyl group, a 2-methylhexyl group, a 3-methylhexyl group, a 2,2-dimethylpentyl group, a 2,3-dimethylpentyl group, a 2,4-dimethylpentyl group, a 3,3-dimethylpentyl group, a 3-ethylpentyl group, a 2,2,3-trimethylbutyl group, an n-octyl group, an isooctyl group, a 2-ethylhexyl group, a nonyl group, and a decyl group.

[0083] Also, R 11 , R 12 , R 13 , R 14 , R 15 and R 16 When is an alkyl group having a substituent, the substituent is a hydroxy group or an amino group. Examples of the alkyl group containing a hydroxy group as a substituent include a hydroxymethyl group, a hydroxyethyl group, and a hydroxypropyl group. Examples of the alkyl group containing an amino group as a substituent include an aminomethyl group, an aminoethyl group, an aminopropyl group, and an aminobutyl group. Examples of the alkyl group containing a hydroxy group and an amino group as a substituent include a hydroxyaminomethyl group, a hydroxyaminoethyl group, and a hydroxyaminopropyl group.

[0084] Among these, R is preferred because it has improved storage stability when made into an aqueous resin composition and low-temperature curing properties when made into a resin film. 11 , R 12 and R 13 are each independently preferably an unsubstituted alkyl group having 1 to 4 carbon atoms, and more preferably a methyl group or an ethyl group.

[0085] R 11 , R 12 and R 13 The total number of carbon atoms is 3 or more and 20 or less, preferably 4 or more and 20 or less, more preferably 4 or more and 12 or less, even more preferably 4 or more and 9 or less, and even more preferably 4 or more and 6 or less. R 11 , R 12 and R 13 When the total number of carbon atoms is equal to or greater than the lower limit, the aqueous resin composition can exhibit storage stability, whereas when the total number of carbon atoms is equal to or less than the upper limit, the aqueous resin composition can exhibit low-temperature curing properties.

[0086] Also, R 14 , R 15 and R 16 are each independently a hydrogen atom or an alkyl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group (preferably an unsubstituted alkyl group having 1 to 4 carbon atoms). Among them, R 14 , R 15 and R 16 Among R, it is preferable that at least one is a hydrogen atom, and it is more preferable that only one is a hydrogen atom. 14 , R15 and R 16 When at least one of these is a hydrogen atom, low-temperature curing properties can be maintained while the storage stability of the aqueous resin composition can be further improved. In other words, it is more preferable that the structural unit (I) contains a structural unit represented by the following general formula (I-1) (hereinafter, sometimes referred to as structural unit (I-1)).

[0087] [ka]

[0088] In the general formula (I-1), R 11 , R 12 , R 13 , R 14 and R 15 is as defined in the general formula (I) above. The wavy line represents the bonding site with the residue of the polyisocyanate excluding the isocyanate group.

[0089] The molar ratio of the structural unit (I-1) in the structural unit (I) (structural unit (I-1) / structural unit (I)) is more preferably 10 mol% or more, even more preferably 30 mol% or more, even more preferably 50 mol% or more, and most preferably 80 mol% or more.

[0090] [Polyisocyanate] The polyisocyanate used in the production of blocked polyisocyanates is a reaction product obtained by reacting multiple monomer compounds having one or more isocyanate groups (-NCO) (hereinafter, sometimes referred to as "isocyanate monomers"). The isocyanate monomer is preferably one having 4 to 30 carbon atoms. Specific examples of the isocyanate monomer include the following. These isocyanate monomers may be used alone or in combination of two or more. (1) Aromatic diisocyanates such as diphenylmethane-4,4'-diisocyanate (MDI), 1,5-naphthalene diisocyanate, tolylene diisocyanate (TDI), xylylene diisocyanate, and m-tetramethylxylylene diisocyanate (TMXDI). (2) Aliphatic diisocyanates such as 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (hereinafter sometimes referred to as "HDI"), 2,2,4-trimethyl-1,6-diisocyanatohexane, 2,4,4-trimethyl-1,6-hexamethylene diisocyanate, 2-methylpentane-1,5-diisocyanate (MPDI), and lysine diisocyanate (hereinafter sometimes referred to as "LDI"). (3) Alicyclic diisocyanates such as isophorone diisocyanate (hereinafter sometimes referred to as "IPDI"), 1,3-bis(diisocyanatemethyl)cyclohexane, 4,4'-dicyclohexylmethane diisocyanate, diisocyanate norbornane, and di(isocyanatemethyl)norbornane. (4) Triisocyanates such as 4-isocyanatomethyl-1,8-octamethylene diisocyanate (hereinafter sometimes referred to as "NTI"), 1,3,6-hexamethylene triisocyanate (hereinafter sometimes referred to as "HTI"), bis(2-isocyanatoethyl) 2-isocyanatoglutarate (hereinafter sometimes referred to as "GTI"), and lysine triisocyanate (hereinafter sometimes referred to as "LTI").

[0091] The isocyanate monomer used in producing the polyisocyanate is preferably one or more diisocyanates selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates because of their excellent weather resistance. Diisocyanate monomers other than the above-mentioned aliphatic diisocyanates and alicyclic diisocyanates may also be used. Furthermore, the isocyanate monomer is more preferably HDI or IPDI because of its ease of industrial availability. Furthermore, the isocyanate monomer is even more preferably HDI because it reduces the viscosity of the blocked polyisocyanate component.

[0092] As the isocyanate monomer used in producing the polyisocyanate, either an aliphatic diisocyanate or an alicyclic diisocyanate may be used alone or in combination, but it is preferable to use a combination of an aliphatic diisocyanate and an alicyclic diisocyanate, and it is particularly preferable to use HDI and IPDI. By using an aliphatic diisocyanate and an alicyclic diisocyanate, the toughness and hardness of the resulting coating film can be further improved.

[0093] In the polyisocyanate, the mass ratio of the constituent units derived from the aliphatic diisocyanate to the constituent units derived from the alicyclic diisocyanate is preferably 50 / 50 or more and 95 / 5 or less, more preferably 60 / 40 or more and 92 / 8 or less, and even more preferably 65 / 35 or more and 90 / 10 or less. When the mass ratio of the structural units derived from the aliphatic diisocyanate to the structural units derived from the alicyclic diisocyanate is equal to or greater than the above lower limit, a decrease in flexibility when formed into a coating film can be more effectively prevented, while when the mass ratio is equal to or less than the above upper limit, the hardness when formed into a coating film can be further improved. The mass ratio of the structural units derived from aliphatic diisocyanates to the structural units derived from alicyclic diisocyanates can be calculated, for example, using the method described in the first embodiment.

[0094] The polyisocyanate preferably has an isocyanurate group, and may have, in addition to the isocyanurate group, one or more functional groups selected from the group consisting of an allophanate group, a uretdione group, an iminooxadiazinedione group, an isocyanurate group, a urethane group, and a biuret group.

[0095] (Polyol B) Examples of polyol B include trimethylolpropane, glycerol, and polycaprolactone polyols derived from trihydric or higher polyhydric alcohols and ε-caprolactone. Commercially available polycaprolactone polyols include, for example, Daicel Corporation's "PLACCEL 303" (number average molecular weight 300), "PLACCEL 305" (number average molecular weight 550), "PLACCEL 308" (number average molecular weight 850), and "PLACCEL 309" (number average molecular weight 900).

[0096] (Production method of polyisocyanate) The method for producing polyisocyanate will be described in detail below. Polyisocyanates can be obtained, for example, by simultaneously carrying out an allophanate reaction to form allophanate groups, a uretdione reaction to form uretdione groups, an iminooxadiazinedione reaction to form iminooxadiazinedione groups, an isocyanurate reaction to form isocyanurate groups, a urethanization reaction to form urethane groups, and a biuret reaction to form biuret groups in the presence of an excess of isocyanate monomer, and then removing the unreacted isocyanate monomer after the completion of the reactions. That is, the polyisocyanate obtained by the above reaction is a reaction product in which a plurality of the above-mentioned isocyanate monomers are bonded together and has one or more groups selected from the group consisting of allophanate groups, uretdione groups, iminooxadiazinedione groups, isocyanurate groups, urethane groups, and biuret groups. Alternatively, the above reactions may be carried out separately and the resulting polyisocyanates may be mixed in a specific ratio. From the viewpoint of ease of production, it is preferable to carry out the above reaction at one time to obtain a polyisocyanate, but from the viewpoint of freely adjusting the molar ratio of each functional group, it is preferable to produce them separately and then mix them.

[0097] (1) Method for producing allophanate group-containing polyisocyanate The allophanate group-containing polyisocyanate can be obtained by adding an alcohol to an isocyanate monomer and using an allophanate reaction catalyst. The alcohol used to form the allophanate group is preferably an alcohol formed only from carbon, hydrogen and oxygen. Specific examples of the alcohol include, but are not limited to, monoalcohols, dialcohols, etc. These alcohols may be used alone or in combination of two or more. Examples of the monoalcohol include methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, and nonanol. Examples of the dialcohol include ethylene glycol, 1,3-butanediol, neopentyl glycol, and 2-ethylhexanediol. Among these, the alcohol is preferably a monoalcohol, and more preferably a monoalcohol having a molecular weight of 200 or less.

[0098] The allophanatization reaction catalyst includes, but is not limited to, alkyl carboxylates of tin, lead, zinc, bismuth, zirconium, zirconyl, and the like. Examples of tin alkylcarboxylates (organotin compounds) include tin 2-ethylhexanoate and dibutyltin dilaurate. Examples of lead alkylcarboxylates (organic lead compounds) include lead 2-ethylhexanoate. Examples of zinc alkylcarboxylates (organic zinc compounds) include zinc 2-ethylhexanoate. Examples of bismuth alkylcarboxylates include bismuth 2-ethylhexanoate. Examples of zirconium alkylcarboxylates include zirconium 2-ethylhexanoate. Examples of zirconyl alkylcarboxylates include zirconyl 2-ethylhexanoate, etc. These catalysts can be used alone or in combination of two or more. Furthermore, an isocyanurate reaction catalyst described below can also serve as an allophanate reaction catalyst. When an allophanate reaction is carried out using an isocyanurate reaction catalyst described below, an isocyanurate group-containing polyisocyanate (hereinafter, sometimes referred to as an "isocyanurate-type polyisocyanate") is naturally also produced. Among these, it is preferable from the viewpoint of economical production to carry out the allophanate formation reaction and the isocyanurate formation reaction using an isocyanurate formation catalyst described below as the allophanate formation reaction catalyst.

[0099] The lower limit of the amount of the allophanate reaction catalyst used is preferably 10 ppm by mass, more preferably 20 ppm by mass, even more preferably 40 ppm by mass, and particularly preferably 80 ppm by mass, relative to the mass of the charged isocyanate monomer. The upper limit of the amount of the allophanate reaction catalyst used is preferably 1000 ppm by mass, more preferably 800 ppm by mass, even more preferably 600 ppm by mass, and particularly preferably 500 ppm by mass, relative to the mass of the charged isocyanate monomer. That is, the amount of the allophanate reaction catalyst used is preferably 10 ppm by mass or more and 1000 ppm by mass or less, more preferably 20 ppm by mass or more and 800 ppm by mass or less, even more preferably 40 ppm by mass or more and 600 ppm by mass or less, and particularly preferably 80 ppm by mass or more and 500 ppm by mass or less, relative to the mass of the charged isocyanate monomer.

[0100] The lower limit of the allophanatization reaction temperature is preferably 40°C, more preferably 60°C, further preferably 80°C, and particularly preferably 100°C. The upper limit of the allophanate reaction temperature is preferably 180°C, more preferably 160°C, and even more preferably 140°C. That is, the allophanate reaction temperature is preferably 40°C or higher and 180°C or lower, more preferably 60°C or higher and 160°C or lower, even more preferably 80°C or higher and 140°C or lower, and particularly preferably 100°C or higher and 140°C or lower. By setting the allophanate reaction temperature to the above lower limit or higher, the reaction rate can be further improved. By setting the allophanate reaction temperature to the above upper limit or lower, coloration of the polyisocyanate tends to be more effectively suppressed.

[0101] (2) Method for producing uretdione group-containing polyisocyanate When a polyisocyanate having a uretdione group is derived from an isocyanate monomer, it can be produced, for example, by polymerizing the isocyanate monomer using a uretdione reaction catalyst or by heat. The uretdione-forming reaction catalyst is not particularly limited, but examples thereof include tertiary phosphines such as trialkylphosphine, tris(dialkylamino)phosphine and cycloalkylphosphine, Lewis acids, and the like. Examples of trialkylphosphines include tri-n-butylphosphine and tri-n-octylphosphine. Examples of tris(dialkylamino)phosphines include tris-(dimethylamino)phosphine. Examples of cycloalkylphosphines include cyclohexyl-di-n-hexylphosphine. Examples of Lewis acids include boron trifluoride and zinc oxychloride.

[0102] Many of the catalysts for the uretdione formation reaction can also promote the isocyanurate formation reaction at the same time. When a uretdione-forming reaction catalyst is used, it is preferable to add a deactivator for the uretdione-forming reaction catalyst such as phosphoric acid or methyl paratoluenesulfonate to terminate the uretdione-forming reaction when the desired yield is achieved. When one or more diisocyanates selected from the group consisting of the aliphatic diisocyanates and the alicyclic diisocyanates are heated without using a uretdione reaction catalyst to obtain a polyisocyanate having uretdione groups, the heating temperature is preferably 120° C. or higher, more preferably 150° C. or higher and 170° C. or lower, and the heating time is preferably 1 hour or longer and 4 hours or shorter.

[0103] (3) Method for producing iminooxadiazinedione group-containing polyisocyanate When an iminooxadiazinedione group-containing polyisocyanate is derived from an isocyanate monomer, an iminooxadiazinedione-forming reaction catalyst is usually used. Examples of the iminooxadiazinedione catalyst include those shown in 1) or 2) below. 1) (Poly)hydrogen fluoride represented by the general formula M[Fn] or M[Fn(HF)m] (wherein m and n are integers satisfying the relationship m / n>0. M is an n-charged cation (mixture) or one or more radicals with a total valence of n). 2) General formula R 1 -CR'2-C(O)O-, or general formula R 2 A compound represented by the formula: ═CR′—C(O)O— and a quaternary ammonium cation or a quaternary phosphonium cation (wherein R 1 and R 2 are each independently a linear, branched, or cyclic, saturated or unsaturated perfluoroalkyl group having from 1 to 30 carbon atoms. A plurality of R's are each independently a hydrogen atom, or an alkyl or aryl group having from 1 to 20 carbon atoms which may contain a heteroatom.

[0104] Specific examples of the compound 1) ((poly)hydrogen fluoride) include tetramethylammonium fluoride hydrate, tetraethylammonium fluoride, and the like. Specific examples of the compound 2) include 3,3,3-trifluorocarboxylic acid, 4,4,4,3,3-pentafluorobutanoic acid, 5,5,5,4,4,3,3-heptafluoropentanoic acid, and 3,3-difluoroprop-2-enoic acid. Among them, as the iminooxadiazinedione-forming reaction catalyst, 1) is preferred from the viewpoint of availability, and 2) is preferred from the viewpoint of safety.

[0105] The lower limit of the amount of the iminooxadiazinedione catalyst used is not particularly limited, but from the viewpoint of reactivity, it is preferably 5 ppm, more preferably 10 ppm, and even more preferably 20 ppm by mass relative to the raw material isocyanate monomer such as HDI. The upper limit of the amount of the iminooxadiazinedione catalyst used is preferably 5000 ppm, more preferably 2000 ppm, and even more preferably 500 ppm by mass relative to the raw material isocyanate monomer such as HDI, from the viewpoint of suppressing coloration and discoloration of the product and controlling the reaction. That is, the amount of the iminooxadiazinedione catalyst used is preferably 5 ppm or more and 5000 ppm or less, more preferably 10 ppm or more and 2000 ppm or less, and even more preferably 20 ppm or more and 500 ppm or less, by mass ratio relative to the raw material isocyanate monomer such as HDI.

[0106] The lower limit of the reaction temperature for the iminooxadiazinedione formation is not particularly limited, but from the viewpoint of the reaction rate, it is preferably 40°C, more preferably 50°C, and even more preferably 60°C. The upper limit of the reaction temperature for the iminooxadiazinedione formation is preferably 150°C, more preferably 120°C, and even more preferably 110°C, from the viewpoint of suppressing coloration and discoloration of the product. That is, the reaction temperature for the iminooxadiazinedione formation is preferably 40°C or higher and 150°C or lower, more preferably 50°C or higher and 120°C or lower, and even more preferably 60°C or higher and 110°C or lower.

[0107] The iminooxadiazinedione formation reaction can be terminated when the desired iminooxadiazinedione group content is reached. The iminooxadiazinedione formation reaction can be terminated, for example, by adding an acidic compound to the reaction solution. Examples of acidic compounds include phosphoric acid, acidic phosphate esters, sulfuric acid, hydrochloric acid, and sulfonic acid compounds. This neutralizes the iminooxadiazinedione formation reaction catalyst or inactivates it by thermal decomposition or chemical decomposition. After the reaction is terminated, filtration is performed, if necessary.

[0108] (4) Method for producing isocyanurate group-containing polyisocyanate Examples of catalysts for deriving polyisocyanates containing isocyanurate groups from isocyanate monomers include commonly used isocyanuration reaction catalysts.

[0109] The isocyanurate reaction catalyst is not particularly limited, but is preferably a basic catalyst in general. Specific examples of the isocyanurate reaction catalyst include the following: 1) Hydroxides of tetraalkylammonium such as tetramethylammonium, tetraethylammonium, and tetrabutylammonium, and organic weak acid salts of the above tetraalkylammonium such as acetate, propionate, octylate, caprate, myristate, and benzoate. 2) Hydroxides of aryltrialkylammonium such as benzyltrimethylammonium and trimethylphenylammonium, and organic weak acid salts of the above aryltrialkylammonium such as acetate, propionate, octylate, caprate, myristate, and benzoate. 3) Hydroxyalkylammonium hydroxides such as trimethylhydroxyethylammonium, trimethylhydroxypropylammonium, triethylhydroxyethylammonium, and triethylhydroxypropylammonium, and organic weak acid salts such as acetates, propionates, octylates, caprates, myristates, and benzoates of the above hydroxyalkylammoniums. 4) Metal salts of tin, zinc, lead, etc. of alkylcarboxylic acids such as acetic acid, propionic acid, caproic acid, octylic acid, capric acid, and myristic acid. 5) Metal alcoholates such as sodium and potassium. 6) Aminosilyl group-containing compounds such as hexamethylenedisilazane. 7) Mannich bases. 8) Mixtures of tertiary amines and epoxy compounds. 9) Phosphorus compounds such as tributylphosphine.

[0110] Among these, from the viewpoint of preventing the generation of unnecessary by-products, the isocyanuration reaction catalyst is preferably a quaternary ammonium hydroxide or a weak organic acid salt of a quaternary ammonium, and more preferably a tetraalkylammonium hydroxide, a weak organic acid salt of a tetraalkylammonium, an aryltrialkylammonium hydroxide, or a weak organic acid salt of an aryltrialkylammonium.

[0111] The upper limit of the amount of the isocyanurate reaction catalyst used is preferably 1000 ppm by mass, more preferably 500 ppm by mass, and even more preferably 100 ppm by mass, relative to the mass of the charged isocyanate monomer. On the other hand, the lower limit of the amount of the isocyanurate reaction catalyst used is not particularly limited, but may be, for example, 10 ppm by mass.

[0112] The isocyanurate reaction temperature is preferably 50° C. or higher and 120° C. or lower, and more preferably 60° C. or higher and 90° C. or lower. When the isocyanurate reaction temperature is equal to or lower than the upper limit, coloration of the polyisocyanate tends to be more effectively suppressed.

[0113] When a desired conversion rate (the ratio by mass of polyisocyanate produced in the isocyanuration reaction to the mass of the charged isocyanate monomer) is reached, the isocyanuration reaction is stopped by adding an acidic compound (e.g., phosphoric acid, acidic phosphate ester, etc.). In order to obtain polyisocyanate, it is necessary to stop the reaction in an early stage. However, since the reaction rate of the isocyanuration reaction is very fast in the early stage, it is difficult to stop the reaction in an early stage, and therefore the reaction conditions, particularly the amount and method of adding the catalyst, must be carefully selected. For example, a method of adding the catalyst in portions at regular intervals is recommended as a suitable method. Therefore, the conversion rate of the isocyanurate reaction to obtain polyisocyanate is preferably 10% or more and 60% or less, more preferably 15% or more and 55% or less, and even more preferably 20% or more and 50% or less. By keeping the conversion rate of the isocyanurate reaction at or below the upper limit, the viscosity of the blocked polyisocyanate component can be further reduced. Furthermore, by keeping the conversion rate of the isocyanurate reaction at or above the lower limit, the reaction termination operation can be more easily carried out.

[0114] When deriving a polyisocyanate containing an isocyanurate group, a monohydric to hexahydric alcohol can be used in addition to the above isocyanate monomer. Examples of alcohols that can be used include non-polymerizable alcohols and polymerizable alcohols. The term "non-polymerizable alcohol" used herein refers to an alcohol that does not have a polymerizable group. Meanwhile, the term "polymerizable alcohol" refers to an alcohol obtained by polymerizing a monomer that has a polymerizable group and a hydroxyl group.

[0115] Examples of non-polymerizable alcohols include polyhydric alcohols such as monoalcohols, diols, triols, and tetraols. Examples of monoalcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, n-pentanol, n-hexanol, n-octanol, n-nonanol, 2-ethylbutanol, 2,2-dimethylhexanol, 2-ethylhexanol, cyclohexanol, methylcyclohexanol, and ethylcyclohexanol. Examples of diols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,2-propanediol, 1,5-pentanediol, and 2-methyl-2,3-butanediol. Examples of the hexanediol include hexanediol, 1,6-hexanediol, 1,2-hexanediol, 2,5-hexanediol, 2-methyl-2,4-pentanediol, 2,3-dimethyl-2,3-butanediol, 2-ethyl-hexanediol, 1,2-octanediol, 1,2-decanediol, 2,2,4-trimethylpentanediol, 2-butyl-2-ethyl-1,3-propanediol, and 2,2-diethyl-1,3-propanediol. Examples of triols include glycerol and trimethylolpropane. An example of the tetraols is pentaerythritol.

[0116] The polymerizable alcohol is not particularly limited, but examples thereof include polyester polyols, polyether polyols, acrylic polyols, and polyolefin polyols. The polyester polyols are not particularly limited, but examples thereof include products obtained by a condensation reaction between a dibasic acid alone or a mixture thereof and a polyhydric alcohol alone or a mixture thereof. The dibasic acid is not particularly limited, but examples thereof include at least one dibasic acid selected from the group consisting of carboxylic acids such as succinic acid, adipic acid, sebacic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid, and terephthalic acid. The polyhydric alcohol is not particularly limited, but examples thereof include at least one polyhydric alcohol selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, and glycerol. Examples of polyester polyols include polycaprolactones obtained by ring-opening polymerization of ε-caprolactone using the above polyhydric alcohols.

[0117] The polyether polyols are not particularly limited, but examples thereof include polyether polyols obtained by adding alkylene oxides, either singly or in mixture, to polyhydric alcohols, either singly or in mixture, using an alkali metal hydroxide or a strongly basic catalyst; polyether polyols obtained by reacting alkylene oxides with polyamine compounds; and so-called polymer polyols obtained by polymerizing acrylamide or the like using the above polyethers as a medium. Examples of alkali metals include lithium, sodium, and potassium. Examples of the strong basic catalyst include alcoholates and alkylamines. Examples of the polyhydric alcohol include the same ones as those exemplified above for the polyester polyols. Examples of alkylene oxides include ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, and styrene oxide. Examples of polyamine compounds include ethylenediamines.

[0118] The acrylic polyols are not particularly limited, but examples thereof include copolymers of a single or a mixture of an ethylenically unsaturated bond-containing monomer having a hydroxyl group and a single or a mixture of other ethylenically unsaturated bond-containing monomers copolymerizable therewith. The ethylenically unsaturated bond-containing monomer having a hydroxyl group is not particularly limited, but examples thereof include hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxybutyl methacrylate. The other ethylenically unsaturated bond-containing monomer copolymerizable with the ethylenically unsaturated bond-containing monomer having a hydroxyl group is not particularly limited, and examples thereof include acrylic acid esters, methacrylic acid esters, unsaturated carboxylic acids, unsaturated amides, vinyl-based monomers, and vinyl-based monomers having a hydrolyzable silyl group. Examples of acrylic acid esters include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, benzyl acrylate, and phenyl acrylate. Examples of methacrylic acid esters include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, benzyl methacrylate, and phenyl methacrylate. Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, and itaconic acid. Examples of unsaturated amides include acrylamide, methacrylamide, N,N-methylenebisacrylamide, diacetone acrylamide, diacetone methacrylamide, maleic acid amide, and maleimide. Examples of vinyl monomers include glycidyl methacrylate, styrene, vinyltoluene, vinyl acetate, acrylonitrile, and dibutyl fumarate. Examples of vinyl monomers having a hydrolyzable silyl group include vinyltrimethoxysilane, vinylmethyldimethoxysilane, and γ-(meth)acryloxypropyltrimethoxysilane.

[0119] Examples of polyolefin polyols include hydroxyl-terminated polybutadiene and hydrogenated products thereof.

[0120] (5) Method for producing urethane group-containing polyisocyanate When a polyisocyanate containing a urethane group is derived from an isocyanate monomer, it can be produced, for example, by mixing an excess of the isocyanate monomer, the polyol B, and, if necessary, an alcohol other than the polyol B, and, if necessary, adding a urethanization reaction catalyst.

[0121] Examples of the alcohol include those exemplified as the "monohydric or greater and hexahydric or less alcohols" above, excluding Polyol B above. The urethanization reaction catalyst is not particularly limited, but examples thereof include tin-based compounds, zinc-based compounds, and amine-based compounds.

[0122] The urethane reaction temperature is preferably 50°C or higher and 160°C or lower, and more preferably 60°C or higher and 120°C or lower. When the urethanization reaction temperature is equal to or lower than the upper limit, coloration of the polyisocyanate tends to be more effectively suppressed. The urethane reaction time is preferably 30 minutes to 4 hours, more preferably 1 hour to 3 hours, and even more preferably 1 hour to 2 hours. The ratio of the molar amount of isocyanate groups of the isocyanate monomer to the molar amount of hydroxyl groups of polyol B (and, if necessary, alcohols other than polyol B) is preferably 2 / 1 or more and 50 / 1 or less. When this molar ratio is equal to or more than the above lower limit, the viscosity of the polyisocyanate can be made lower. When this molar ratio is equal to or less than the above upper limit, the yield of the urethane group-containing polyisocyanate can be made higher.

[0123] (6) Method for producing biuret group-containing polyisocyanate The biuretizing agent for deriving a polyisocyanate containing a biuret group from an isocyanate monomer is not particularly limited, but examples thereof include water, monohydric tertiary alcohols, formic acid, organic primary monoamines, and organic primary diamines. The amount of isocyanate groups per mole of biuretizing agent is preferably 6 moles or more, more preferably 10 moles or more, and even more preferably 10 moles or more but 80 moles or less. When the molar amount of isocyanate groups per mole of biuretizing agent is equal to or greater than the above-mentioned lower limit, the viscosity of the polyisocyanate becomes sufficiently low, and when it is equal to or less than the above-mentioned upper limit, the low-temperature curing property of the resin film formed is further improved.

[0124] A solvent may be used in the biuretization reaction, as long as it dissolves the isocyanate monomer and the biuretization agent such as water and forms a homogeneous phase under the reaction conditions. Specific examples of the solvent include ethylene glycol-based solvents and phosphoric acid-based solvents. Examples of ethylene glycol solvents include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-propyl ether acetate, ethylene glycol monoisopropyl ether acetate, ethylene glycol mono-n-butyl ether acetate, ethylene glycol diacetate, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol di-n-propyl ether, ethylene glycol diisopropyl ether, ethylene glycol di-n-butyl ether, ethylene glycol methyl ethyl ether, ethylene glycol methyl isopropyl ether, ethylene glycol methyl-n-butyl ether, ethylene glycol ethyl-n-propyl ether, ethylene glycol ethyl isopropyl ether, ethylene glycol ethyl-n-butyl ether, ethylene glycol-n-propyl-n-butyl ether, ethylene glycol isopropyl-n-butyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-propyl ether acetate, diethylene glycol monoisopropyl ether acetate, diethylene glycol mono-n-butyl ether acetate, diethylene glycol diacetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-propyl ether, diethylene glycol diisopropyl ether, diethylene glycol di-n-butyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl isopropyl ether, diethylene glycol methyl-n-propyl ether, diethylene glycol methyl-n-butyl ether, diethylene glycol ethyl isopropyl ether, diethylene glycol ethyl-n-propyl ether, diethylene glycol ethyl-n-butyl ether, diethylene glycol-n-propyl-n-butyl ether, and diethylene glycol isopropyl-n-butyl ether. Examples of the phosphoric acid solvent include trimethyl phosphate, triethyl phosphate, tripropyl phosphate, and tributyl phosphate. These solvents may be used alone or in combination of two or more. Among these, the ethylene glycol solvent is preferably ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol diacetate, or diethylene glycol dimethyl ether. As the phosphoric acid-based solvent, trimethyl phosphate or triethyl phosphate is preferred.

[0125] The biuretization reaction temperature is preferably 70° C. or higher and 200° C. or lower, and more preferably 90° C. or higher and 180° C. or lower. By keeping the temperature at or below the upper limit, coloration of the polyisocyanate tends to be more effectively prevented.

[0126] The above-mentioned allophanate formation reaction, uretdione formation reaction, iminooxadiazinedione formation reaction, isocyanurate formation reaction, urethanization reaction, and biuret formation reaction may be carried out sequentially, or some of them may be carried out in parallel. After the reaction is completed, unreacted isocyanate monomer can be removed from the reaction mixture by thin film distillation, extraction, or the like to obtain a polyisocyanate.

[0127] Furthermore, an antioxidant or an ultraviolet absorber may be added to the obtained polyisocyanate, for example, for the purpose of suppressing coloration during storage. Examples of antioxidants include hindered phenols such as 2,6-di-tert-butyl-p-cresol. Examples of ultraviolet absorbers include benzotriazole and benzophenone. These antioxidants and ultraviolet absorbers may be used alone or in combination of two or more. The amount of these added is preferably 10 ppm by mass or more and 500 ppm by mass or less relative to the mass of polyisocyanate.

[0128] [Active hydrogen compounds] The active hydrogen compound in this embodiment is the same as the active hydrogen compound in the first embodiment.

[0129] [Polyol A] In this embodiment, polyol A is also preferred as the active hydrogen compound. In the molecule of the blocked polyisocyanate, a hydroxyl group of the polyol A and an isocyanate group of the polyisocyanate form a urethane bond, and a structural unit derived from the polyol A is bonded to the polyisocyanate. Alternatively, a hydroxyl group of the polyol A and an ester group of the blocked polyisocyanate are bonded by a transesterification reaction.

[0130] Examples of such polyol A include 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanedimethanol, glycerol, polycaprolactone polyols derived from any of these and ε-caprolactone, and one or more polyols selected from the group consisting of polyether polyols, polycarbonate polyols, and acrylic polyols. Among these, one or more diols selected from the group consisting of 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanedimethanol, and glycerol, or polycaprolactone diols derived from these diols and ε-caprolactone are preferred, one or more diols selected from the group consisting of 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, and 1,4-cyclohexanedimethanol, or polycaprolactone diols derived from these diols and ε-caprolactone are more preferred, and 1,4-butanediol or polycaprolactone diol is even more preferred. Commercially available polycaprolactone diols include those described in the first embodiment.

[0131] The molar ratio (OH / structural unit (I)) of the hydroxy groups contained in polyol A to the structural unit (I) is preferably 0.5 / 99.5 to 15 / 85, and more preferably 6 / 94 to 15 / 85. When the molar ratio (OH / structural unit (I)) is within the above range, the blocked polyisocyanate composition has a highly flexible structure, and is more likely to form a crosslinked structure when mixed with the base resin, which tends to improve the low-temperature curability, hardness, strength, and solvent resistance of the resulting coating film. The content (mol) of hydroxy groups contained in polyol A is calculated from the blend amounts of polyol A and blocking agent or measured by gas chromatography / mass spectrometry (GC / MS), and the content (mol) of structural unit (I) is 13 It is measured by C-NMR.

[0132] [Blocking agent] The blocking agent includes a malonate ester.

[0133] (Malonate ester with tertiary alkyl group) The blocking agent preferably contains a malonic acid ester having a tertiary alkyl group. The blocking agent may contain one type of malonic acid ester having a tertiary alkyl group, or may contain two or more types of malonic acid esters having a tertiary alkyl group. The malonic acid ester having a tertiary alkyl group is not particularly limited, and the same malonic acid esters as those in the first embodiment can be used.

[0134] (Malonate ester with secondary alkyl group) The blocking agent preferably contains a malonic acid ester having a secondary alkyl group. The blocking agent may contain one type of malonic acid ester having a secondary alkyl group, or may contain two or more types of malonic acid esters having a secondary alkyl group. The malonic acid ester having a secondary alkyl group is not particularly limited, but the same malonic acid esters as those in the first embodiment can be used.

[0135] Among these, it is preferable that the blocking agent contains diisopropyl malonate as a malonic acid ester having a secondary alkyl group, and di-tert-butyl malonate or (2-methyl-2-butyl)isopropyl malonate as a malonic acid ester having a tertiary alkyl group.

[0136] (Other blocking agents) The blocking agent used in producing the blocked polyisocyanate may further contain other blocking agents in addition to the malonic acid ester having a secondary alkyl group and the malonic acid ester having a tertiary alkyl group, as long as they do not impair the storage stability of the resin composition or the low-temperature curing property of the resin film. As the other blocking agents, the same ones as those in the first embodiment can be used.

[0137] With respect to the total molar amount of all blocking agents used in the production of the blocked polyisocyanate, the content of the malonic acid ester having a secondary alkyl group and the malonic acid ester having a tertiary alkyl group is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, particularly preferably 95 mol% or more, and most preferably 100 mol%. When the content of the malonic acid ester having a secondary alkyl group and the malonic acid ester having a tertiary alkyl group is within the above range, the low-temperature curing property of the resin film can be further improved.

[0138] [Hydrophilic compound] At least a portion of the blocked polyisocyanate may have a structural unit derived from a hydrophilic compound, i.e., a hydrophilic group.

[0139] The hydrophilic compound is a compound having a hydrophilic group. In addition to the hydrophilic group, the hydrophilic compound preferably has one or more active hydrogen groups per molecule of the hydrophilic compound, which are capable of reacting with at least one isocyanate group of the polyisocyanate. Specific examples of the active hydrogen groups include hydroxyl groups, mercapto groups, carboxylic acid groups, amino groups, and thiol groups.

[0140] Examples of hydrophilic compounds include nonionic compounds, cationic compounds, and anionic compounds. These hydrophilic compounds may be used alone or in combination of two or more. Among them, nonionic compounds are preferred as hydrophilic compounds from the viewpoints of availability and being less susceptible to electrical interaction with the compound, and anionic compounds are preferred from the viewpoint of suppressing a decrease in the hardness of the resulting resin film.

[0141] (nonionic compounds) Specific examples of nonionic compounds include monoalcohols and compounds in which ethylene oxide is added to the hydroxyl group of an alcohol. Examples of monoalcohols include methanol, ethanol, and butanol. Examples of compounds in which ethylene oxide is added to the hydroxyl group of an alcohol include ethylene glycol, diethylene glycol, and polyethylene glycol. These nonionic compounds also have active hydrogen groups that react with isocyanate groups. Among these, polyethylene glycol monoalkyl ethers in which ethylene oxide is added to the hydroxyl group of a monoalcohol are preferred as nonionic compounds, since they can improve the water dispersibility of the blocked polyisocyanate composition even with a small amount used.

[0142] The number of ethylene oxide addition units in the ethylene oxide-added compound is preferably 4 or more and 30 or less, and more preferably 4 or more and 25 or less. When the number of ethylene oxide addition units is equal to or more than the above-mentioned lower limit, water dispersibility tends to be more effectively imparted to the blocked polyisocyanate composition, and when the number of ethylene oxide addition units is equal to or less than the above-mentioned upper limit, the blocked polyisocyanate composition tends to be less likely to precipitate during low-temperature storage.

[0143] From the viewpoint of the aqueous dispersion stability of the blocked polyisocyanate composition, the lower limit of the amount of nonionic hydrophilic groups added to the blocked polyisocyanate (hereinafter, may be referred to as the "nonionic hydrophilic group content") is preferably 0.1 mass%, more preferably 0.15 mass%, even more preferably 0.20 mass%, and particularly preferably 0.25 mass%, relative to the mass of the solid content of the hydrophilic polyisocyanate composition. Furthermore, from the viewpoint of the water resistance of the resulting resin film, the upper limit of the content of the nonionic hydrophilic group is preferably 55 mass%, more preferably 50 mass%, even more preferably 48 mass%, and particularly preferably 44 mass%, relative to the mass of the solid content of the blocked polyisocyanate composition. That is, the content of the nonionic hydrophilic group is preferably 0.1 mass % or more and 55 mass % or less, more preferably 0.15 mass % or more and 50 mass % or less, even more preferably 0.20 mass % or more and 48 mass % or less, and particularly preferably 0.25 mass % or more and 44 mass % or less, relative to the mass of the solid content of the blocked polyisocyanate composition. When the content of the nonionic hydrophilic group is within the above range, the blocked polyisocyanate composition tends to be more dispersible in water, and a homogeneous film tends to be obtained.

[0144] When the amount of nonionic hydrophilic groups added to the blocked polyisocyanate is expressed as a molar ratio, it is preferably from 0.05 mol % to 8 mol % relative to 100 mol % of the isocyanate groups in the raw material polyisocyanate, more preferably from 0.10 mol % to 5 mol %, even more preferably from 0.15 mol % to 4 mol %, particularly preferably from 0.15 mol % to 3 mol %, and most preferably from 0.15 mol % to 2 mol %.

[0145] (cationic compounds) As the cationic compound, specifically, a compound having both a cationic hydrophilic group and an active hydrogen group can be mentioned.In addition, a compound having an active hydrogen group such as a glycidyl group and a compound having a cationic hydrophilic group such as sulfide or phosphine can be combined to form a hydrophilic compound.In this case, a compound having an isocyanate group and a compound having an active hydrogen group are reacted in advance to add a functional group such as a glycidyl group, and then a compound such as sulfide or phosphine is reacted.From the viewpoint of ease of production, a compound having both a cationic hydrophilic group and an active hydrogen group is preferred.

[0146] Specific examples of compounds having both a cationic hydrophilic group and an active hydrogen group include dimethylethanolamine, diethylethanolamine, diethanolamine, methyldiethanolamine, etc. Tertiary amino groups added using these compounds can also be quaternized with, for example, dimethyl sulfate or diethyl sulfate.

[0147] The reaction between the cationic compound and the alicyclic polyisocyanate can be carried out in the presence of a solvent. In this case, the solvent is preferably one that does not contain an active hydrogen group, and specific examples thereof include ethyl acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol dimethyl ether.

[0148] The cationic hydrophilic groups added to the blocked polyisocyanate are preferably neutralized with a compound having an anionic group, such as a carboxy group, a sulfonic acid group, a phosphate group, a halogen group, or a sulfate group. Specific examples of compounds having a carboxyl group include formic acid, acetic acid, propionic acid, butyric acid, and lactic acid. Specific examples of compounds having a sulfonic acid group include ethanesulfonic acid. Specific examples of compounds having a phosphate group include phosphoric acid and acidic phosphate esters. Specific examples of compounds having a halogen group include hydrochloric acid. Specific examples of compounds having a sulfate group include sulfuric acid. Among these, compounds having an anionic group are preferably compounds having a carboxy group, and more preferably acetic acid, propionic acid or butyric acid.

[0149] (anionic compounds) Specific examples of the anionic hydrophilic group include a carboxy group, a sulfonic acid group, a phosphate group, a halogen group, and a sulfate group. Specific examples of the anionic compound include compounds having both an anionic group and an active hydrogen group, and more specific examples include compounds having a carboxy group of a monohydroxycarboxylic acid or polyhydroxycarboxylic acid as the anionic group. Examples of monohydroxycarboxylic acids include 1-hydroxyacetic acid, 3-hydroxypropanoic acid, 12-hydroxy-9-octadecanoic acid, hydroxypivalic acid, and lactic acid. Examples of compounds having a carboxy group of a polyhydroxycarboxylic acid as an anionic group include dimethylolacetic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolpentanoic acid, dihydroxysuccinic acid, and dimethylolpropionic acid. Further, compounds having both a sulfonic acid group and an active hydrogen group are also included, and more specifically, for example, isethionic acid is included. Among these, hydroxypivalic acid or dimethylolpropionic acid is preferred as a compound having both an anionic group and an active hydrogen group.

[0150] The anionic hydrophilic group added to the blocked polyisocyanate is preferably neutralized with an amine compound, which is a basic substance. Specific examples of the amine compound include ammonia and water-soluble amino compounds. Specific examples of water-soluble amino compounds include monoethanolamine, ethylamine, dimethylamine, diethylamine, triethylamine, propylamine, dipropylamine, isopropylamine, diisopropylamine, triethanolamine, butylamine, dibutylamine, 2-ethylhexylamine, ethylenediamine, propylenediamine, methylethanolamine, dimethylethanolamine, diethylethanolamine, and morpholine. Tertiary amines such as triethylamine and dimethylethanolamine can also be used. These amine compounds may be used alone or in combination of two or more.

[0151] <Other components> The blocked polyisocyanate composition of the present embodiment may further contain additives such as a solvent in addition to the blocked polyisocyanate. As the solvent, the same solvent as in the first embodiment can be used.

[0152] <Method for producing blocked polyisocyanate composition> The blocked polyisocyanate composition is not particularly limited, and can be obtained, for example, by reacting the polyisocyanate, the active hydrogen compound, and the blocking agent. The blocked polyisocyanate composition may be produced by simultaneously reacting these compounds. The blocked polyisocyanate composition may be produced by reacting the polyisocyanate with the active hydrogen compound to produce an active hydrogen compound-modified polyisocyanate, and then reacting the active hydrogen compound-modified polyisocyanate with a blocking agent. Alternatively, the blocked polyisocyanate composition may be produced by reacting the polyisocyanate with the blocking agent to produce a partially blocked polyisocyanate in which some or all of the isocyanate groups of the polyisocyanate are blocked with a blocking agent, and then reacting the partially blocked polyisocyanate with the active hydrogen compound.

[0153] The modification reaction between the polyisocyanate (or partially blocked polyisocyanate) and the active hydrogen compound can be carried out regardless of the presence or absence of a solvent. The amount of the active hydrogen compound added is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 9 parts by mass, even more preferably 0.25 to 8 parts by mass, and even more preferably 0.3 to 7 parts by mass, per 100 parts by mass of polyisocyanate. When the amount of the active hydrogen compound added is equal to or greater than the above-mentioned lower limit, the resulting coating tends to exhibit excellent curability, hardness, and strength at low temperatures of about 80°C. On the other hand, when the amount of the active hydrogen compound added is equal to or less than the above-mentioned upper limit, gelation during synthesis of the blocked polyisocyanate composition can be suppressed, and the resulting resin composition can exhibit good storage stability.

[0154] When a solvent is used during the modification reaction between the polyisocyanate (or partially blocked polyisocyanate) and the active hydrogen compound, it is sufficient to use a solvent that is inactive to the isocyanate group. The reaction temperature between the polyisocyanate (or partially blocked polyisocyanate) and the active hydrogen compound is preferably 50°C or higher and 160°C or lower, and more preferably 60°C or higher and 120°C or lower. When the reaction temperature is equal to or higher than the lower limit, the reactivity tends to be higher, whereas when the reaction temperature is equal to or lower than the upper limit, coloration and gelation of the polyisocyanate tend to be more effectively suppressed.

[0155] The blocking reaction between polyisocyanate (or active hydrogen compound-modified polyisocyanate) and a blocking agent is not particularly limited, but similar to the blocking reaction between diisocyanate and a blocking agent in the first embodiment, for example, the following two methods can be mentioned. 1) A method of reacting the above polyisocyanate (or active hydrogen compound-modified polyisocyanate) with the above malonic acid ester having a tertiary alkyl group, and the above malonic acid ester having a secondary alkyl group or the above malonic acid ester having a primary alkyl group. 2) A method in which the polyisocyanate (or active hydrogen compound-modified polyisocyanate) is reacted with at least one blocking agent selected from the group consisting of the malonic acid ester having a tertiary alkyl group, the malonic acid ester having a secondary alkyl group, and the malonic acid ester having a primary alkyl group, and an alcohol having a chain alkyl group is added to the resulting reaction product to introduce an alkyl group derived from the alcohol by transesterification of the terminal ester moiety of the reaction product. The blocking reaction between the polyisocyanate (or the active hydrogen compound-modified polyisocyanate) and the blocking agent can be carried out regardless of the presence or absence of a solvent.

[0156] The amount of the blocking agent added may usually be 80 mol % or more and 200 mol % or less, and preferably 90 mol % or more and 150 mol % or less, based on the total molar amount of isocyanate groups.

[0157] Furthermore, when a malonic acid ester having a secondary alkyl group and a malonic acid ester having a tertiary alkyl group are used in the blocking agent to be added, the molar ratio of the malonic acid ester having a secondary alkyl group to the malonic acid ester having a tertiary alkyl group (secondary alkyl malonic acid ester / tertiary alkyl malonic acid ester) is more than 5 / 95 and less than 95 / 5, preferably 7 / 93 or more and 93 / 7 or less, more preferably 10 / 90 or more and 93 / 7 or less, even more preferably 20 / 80 or more and 93 / 7 or less, and particularly preferably 30 / 70 or more and 93 / 7 or less. When the molar ratio is equal to or greater than the lower limit, the storage stability of the resin composition can be improved, and when the molar ratio is equal to or less than the upper limit, the low-temperature curing properties of the resin film can be improved.

[0158] When a solvent is used during the blocking reaction, it is sufficient to use a solvent that is inactive to isocyanate groups. When a solvent is used, the content of the solvent (non-volatile content) per 100 parts by mass of the blocked polyisocyanate composition may usually be 10 parts by mass or more and 95 parts by mass or less, preferably 20 parts by mass or more and 80 parts by mass or less, and more preferably 30 parts by mass or more and 75 parts by mass or less.

[0159] In the blocking reaction, organic metal salts of tin, zinc, lead, etc., tertiary amine compounds, alcoholates of alkali metals such as sodium, etc., may be used as catalysts. The amount of catalyst added varies depending on the temperature of the blocking reaction, etc., but is usually from 0.05 to 1.5 parts by mass, preferably from 0.1 to 1.0 part by mass, per 100 parts by mass of polyisocyanate.

[0160] The blocking reaction can generally be carried out at a temperature of −20° C. or higher and 150° C. or lower, preferably at a temperature of 0° C. or higher and 100° C. or lower, and more preferably at a temperature of 10° C. or higher and 80° C. When the temperature of the blocking reaction is equal to or higher than the lower limit, the reaction rate can be increased, and when the temperature is equal to or lower than the upper limit, side reactions can be suppressed.

[0161] After the blocking reaction, a neutralization treatment may be carried out by adding an acidic compound or the like. As the acidic compound, those described in the first embodiment can be used.

[0162] When the polyisocyanate is produced by the above method 2), the blocking reaction is followed by an ester exchange reaction. As the alcohol having a chain alkyl group used in the transesterification reaction in method 2), the same alcohols as those in the first embodiment can be used. The chain alkyl group of the alcohol may be the same as or different from that of the blocking agent. When the chain alkyl group is different from that of the blocking agent, it is preferable to use a monoalcohol having a chain alkyl group with a different number of alkyl substitutions than that of the blocking agent. Specifically, for example, when a single malonic acid ester having a secondary alkyl group is used as the blocking agent, a monoalcohol having a tertiary alkyl group can be used.

[0163] In the case of producing by the method 2), it is preferable to remove the generated alcohol or the residual added alcohol during or after the transesterification reaction by distillation under normal pressure or reduced pressure. Among these, in order to efficiently proceed with the transesterification reaction, it is preferable to remove the generated alcohol by performing an operation such as distillation during the transesterification reaction. In this case, in order to efficiently remove the alcohol component generated by the transesterification reaction, it is more preferable that the alcohol component to be added has a boiling point higher than that of the generated alcohol component. The transesterification reaction can generally be carried out at a temperature of 0° C. or higher and 150° C. or lower, preferably 30° C. or higher and 120° C. or lower, and more preferably 50° C. or higher and 100° C. When the temperature of the transesterification reaction is equal to or higher than the lower limit, the reaction rate can be further increased, and when the temperature is equal to or lower than the upper limit, side reactions can be further suppressed.

[0164] The amount of the alcohol component in the blocked polyisocyanate composition is preferably 0.05 to 41 parts by mass, more preferably 0.1 to 30 parts by mass, and even more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the solids content of the blocked polyisocyanate composition. When the amount of the alcohol component is at least the above lower limit, the storage stability of the paint is improved, and when it is at most the above upper limit, thickening of the aqueous paint during formulation can be suppressed.

[0165] When a hydrophilic compound is used, the polyisocyanate, the active hydrogen compound, the blocking agent and the hydrophilic compound may be reacted with each other.

[0166] The reaction between the polyisocyanate and the active hydrogen compound, the reaction between the polyisocyanate and the hydrophilic compound, and the reaction between the polyisocyanate and the blocking agent can be carried out simultaneously, or one of the reactions can be carried out in advance before the second or subsequent reaction. It is particularly preferred to carry out the reaction between the polyisocyanate and the hydrophilic compound first to obtain a hydrophilic compound-modified polyisocyanate modified with the hydrophilic compound, and then to react the obtained hydrophilic compound-modified polyisocyanate with an active hydrogen compound or a blocking agent simultaneously or sequentially. Either the reaction between the hydrophilic compound-modified polyisocyanate and the active hydrogen compound or the reaction between the hydrophilic compound-modified polyisocyanate and the blocking agent can be carried out first.

[0167] The reaction between polyisocyanate and hydrophilic compound may be carried out using an organic metal salt, a tertiary amine compound, or an alcoholate of an alkali metal as a catalyst. Examples of metals constituting the organic metal salt include tin, zinc, and lead. Examples of the alkali metal include sodium.

[0168] The reaction temperature between the polyisocyanate and the hydrophilic compound is preferably −20° C. or higher and 150° C. or lower, and more preferably 30° C. or higher and 130° C. or lower. When the reaction temperature is equal to or higher than the lower limit, reactivity tends to be increased. Furthermore, when the reaction temperature is equal to or lower than the upper limit, side reactions tend to be more effectively suppressed.

[0169] It is preferable to completely react the hydrophilic compound with the polyisocyanate so that no unreacted hydrophilic compound remains, which tends to more effectively prevent the aqueous dispersion stability of the blocked polyisocyanate composition and the low-temperature curing properties of the resulting resin film from being deteriorated.

[0170] The reaction between the hydrophilic compound-modified polyisocyanate and the active hydrogen compound, and the reaction between the hydrophilic compound-modified polyisocyanate and the blocking agent can be carried out using the methods described above for the active hydrogen compound modification reaction and the blocking reaction.

[0171] <Characteristics of Blocked Polyisocyanate Composition> [Weight average molecular weight Mw] The weight average molecular weight Mw of the blocked polyisocyanate composition of this embodiment is 3.0 × 10 3 More than 3.0 × 10 is preferable. 3 Over 2.0 x 10 5 Less than 4.0 x 10 is preferable. 3 Over 1.5 x 10 5 More preferably, 4.0 x 10 3 Over 7.0 x 10 4 The following is most preferred. By having the weight-average molecular weight Mw within the above range, the viscosity of the blocked polyisocyanate composition can be maintained at a better level. The weight-average molecular weight Mw can be measured, for example, by gel permeation chromatography (hereinafter sometimes abbreviated as "GPC").

[0172] Blocked polyisocyanate composition of the third embodiment The blocked polyisocyanate composition according to the third embodiment of the present invention comprises a blocked polyisocyanate derived from a polyisocyanate and one or more blocking agents, and the blocked polyisocyanate comprises the structural unit (I). In this embodiment, the description of the same configuration as in the first embodiment or the second embodiment may be omitted.

[0173] [Blocked polyisocyanate] Unit The blocked polyisocyanate contained in the blocked polyisocyanate composition of the present embodiment contains a structural unit (I) represented by the following general formula (I) in its molecule.

[0174] [ka]

[0175] In the general formula (I), R 11 , R 12 and R 13 are each independently an alkyl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group, and R 11 , R 12 and R 13 The total number of carbon atoms in R is 4 or more and 20 or less, 14 , R 15 and R 16 are each independently a hydrogen atom or an alkyl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group, and the wavy line represents the bonding site with the residue of the polyisocyanate excluding the isocyanate group.

[0176] R 11 , R 12 , R 13 , R 14 , R 15 and R 16The alkyl group in the formula (I) preferably has 1 to 20 carbon atoms, more preferably 1 to 8 carbon atoms, further preferably 1 to 6 carbon atoms, and particularly preferably 1 to 4 carbon atoms.

[0177] Examples of the alkyl group having no substituent include the same groups as those in the second embodiment. Examples of the alkyl group containing a hydroxy group as a substituent, the alkyl group containing an amino group as a substituent, and the alkyl group containing a hydroxy group and an amino group as substituents include the same groups as in the second embodiment. Among these, R is preferred because it has improved storage stability when made into an aqueous resin composition and low-temperature curing properties when made into a resin film. 11 , R 12 and R 13 are each independently preferably an unsubstituted alkyl group having 1 to 4 carbon atoms, more preferably a methyl group or an ethyl group, and at least one of them is preferably an ethyl group.

[0178] R 11 , R 12 and R 13 The total number of carbon atoms is 4 or more and 20 or less, more preferably 4 or more and 12 or less, even more preferably 4 or more and 9 or less, and even more preferably 4 or more and 6 or less. R 11 , R 12 and R 13 When the total number of carbon atoms in R is equal to or greater than the lower limit, storage stability can be exhibited when the aqueous resin composition is prepared. On the other hand, when the total number of carbon atoms in R is equal to or less than the upper limit, low-temperature curing properties can be exhibited. In addition, from the viewpoint of solvent resistance when the coating film is prepared, 11 , R 12 and R 13 The total number of carbon atoms is more preferably 4.

[0179] Also, R 14 , R 15 and R 16are each independently a hydrogen atom or an alkyl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group (preferably an unsubstituted alkyl group having 1 to 4 carbon atoms). Among them, R 14 , R 15 and R 16 Among R, it is preferable that at least one is a hydrogen atom, and it is more preferable that only one is a hydrogen atom. 14 , R 15 and R 16 When at least one of these is a hydrogen atom, low-temperature curing properties can be maintained while the storage stability of the aqueous resin composition can be further improved. In other words, it is more preferable that the structural unit (I) contains a structural unit represented by the following general formula (I-1) (hereinafter, sometimes referred to as structural unit (I-1)).

[0180] [ka]

[0181] In the general formula (I-1), R 11 , R 12 , R 13 , R 14 and R 15 is as defined in the general formula (I) above. The wavy line represents the bonding site with the residue of the polyisocyanate excluding the isocyanate group.

[0182] The molar ratio of the structural unit (I-1) in the structural unit (I) (structural unit (I-1) / structural unit (I)) is more preferably 10 mol% or more, even more preferably 30 mol% or more, even more preferably 50 mol% or more, even more preferably 80 mol% or more, and even more preferably 90 mol% or more.

[0183] [Constituent Unit (II)] The blocked polyisocyanate molecule contained in the blocked polyisocyanate composition of the present embodiment preferably further contains a structural unit represented by the following general formula (II) (hereinafter, sometimes referred to as structural unit (II)).

[0184] [ka]

[0185] In the general formula (II), R 21 , R 22 , R 23 and R 24 are each independently a hydrogen atom or an alkyl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group, and the wavy line represents the bonding site with the residue of the polyisocyanate excluding the isocyanate group.

[0186] R 21 , R 22 , R 23 and R 24 The alkyl group which may have one or more substituents selected from the group consisting of a hydroxy group and an amino group in the above formula "R 11 , R 12 , R 13 , R 14 , R 15 and R 16 " are examples of the same.

[0187] Among them, R 21 , R 22 , R 23 and R 24 As the alkyl group, a hydrogen atom or an alkyl group having 1 to 4 carbon atoms and no substituent is preferred because they provide excellent storage stability when made into an aqueous resin composition, a hydrogen atom, a methyl group, or an ethyl group is more preferred, and a methyl group or an ethyl group is even more preferred because they provide excellent low-temperature curing properties. R 21 , R 22 , R 23 and R 24When all of R are methyl groups, the two ester moieties of the malonic acid ester of the structural unit (II) are both isopropyl groups. 21 and R 22 one of which is a hydrogen atom and the other is a methyl group, and R 23 and R 24 When one of R is a hydrogen atom and the other is a methyl group, the two ester moieties of the malonic acid ester of the structural unit (II) are both ethyl groups. 21 , R 22 , R 23 and R 24 are all methyl groups, that is, the two ester moieties of the malonic acid ester of the structural unit (II) are both isopropyl groups.

[0188] The molar ratio of the structural unit represented by the general formula (II) to the structural unit represented by the general formula (I) (structural unit (II) / structural unit (I)) is preferably 4 / 96 or more and 96 / 4 or less, more preferably 5 / 95 or more and 95 / 5 or less, even more preferably 7 / 93 or more and 93 / 7 or less, even more preferably 10 / 90 or more and 90 / 10 or less, even more preferably 20 / 80 or more and 85 / 15 or less, even more preferably 30 / 70 or more and 85 / 15 or less, even more preferably 35 / 65 or more and 85 / 15 or less, and even more preferably 50 / 50 or more and 70 / 30 or less. By having the molar ratio be above the lower limit, the storage stability when formed into a resin composition can be improved, and by having the molar ratio be below the upper limit, the low-temperature curing properties when formed into a resin film can be improved. The molar ratio may be, for example, the following: 1 H-NMR and 13 The molar ratio of structural unit (II) to structural unit (I) can be calculated by measuring the composition ratio of structural unit (II) to structural unit (I) by C-NMR.

[0189] In general formula (I), R 11 , R 12 and R 13are all methyl, i.e., at least one ester group in the diester moiety is a tert-butyl group, are known to have excellent curability with polyhydroxy compounds at low temperatures of around 85°C. However, in aqueous resin compositions, they have high reactivity with water, and when blended into an aqueous resin composition and stored as an aqueous resin composition containing a polyhydroxy compound, a curing agent, and water, they tend to easily increase in viscosity and gel. In contrast, the blocked polyisocyanate composition of the present embodiment has a structure in which R 11 , R 12 and R 13 When the total number of carbon atoms is 4 or more and 20 or less, the mixture of the polyhydroxy compound, the curing agent, and water can be effectively prevented from increasing in viscosity or gelling during storage, even when blended into an aqueous resin composition, and a resin film with excellent curing properties can be obtained at a low temperature of about 85°C.

[0190] The blocked polyisocyanate composition of this embodiment may be a blocked polyisocyanate in which at least some of the isocyanate groups in the molecule are blocked with a malonic acid ester having a secondary alkyl group or a malonic acid ester having a primary alkyl group and a malonic acid ester having a tertiary alkyl group. Alternatively, the blocked polyisocyanate composition may be a mixture of a blocked polyisocyanate in which at least some of the isocyanate groups in the polyisocyanate are blocked with a malonic acid ester having a secondary alkyl group, or a blocked polyisocyanate in which at least some of the isocyanate groups in the polyisocyanate are blocked with a malonic acid ester having a primary alkyl group and a blocked polyisocyanate in which at least some of the isocyanate groups in the polyisocyanate are blocked with a malonic acid ester having a tertiary alkyl group.

[0191] [Other functional groups] The blocked polyisocyanate may have one or more functional groups selected from the group consisting of an allophanate group, a uretdione group, an iminooxadiazinedione group, an isocyanurate group, a urethane group, and a biuret group. Among these, an isocyanurate group is preferred because it provides excellent weather resistance.

[0192] The blocked polyisocyanate contained in the blocked polyisocyanate composition of this embodiment is derived from a polyisocyanate obtained by a similar method using the same isocyanate as in the second embodiment, and at least one blocking agent.

[0193] [Polyisocyanate] (Isocyanate) As in the second embodiment, the isocyanate monomer used in producing the polyisocyanate is preferably one or more diisocyanates selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates because of their excellent weather resistance. Furthermore, HDI or IPDI is more preferably used because of its ease of industrial availability. Furthermore, HDI is even more preferably used from the viewpoint of achieving a low viscosity for the blocked polyisocyanate component.

[0194] As the isocyanate monomer used in producing the polyisocyanate, either an aliphatic diisocyanate or an alicyclic diisocyanate may be used alone or in combination, but it is preferable to use a combination of an aliphatic diisocyanate and an alicyclic diisocyanate, and it is particularly preferable to use HDI and IPDI. By using an aliphatic diisocyanate and an alicyclic diisocyanate, the toughness and hardness of the resulting coating film can be further improved.

[0195] In the polyisocyanate, from the viewpoint of improving the coating film hardness and strength, the mass ratio of the constituent units derived from the aliphatic diisocyanate to the constituent units derived from the alicyclic diisocyanate (constituent units derived from the aliphatic diisocyanate / constituent units derived from the alicyclic diisocyanate) is preferably 50 / 50 or more and 95 / 5 or less, more preferably 55 / 45 or more and 93 / 7 or less, even more preferably 60 / 40 or more and 91 / 9 or less, and even more preferably 65 / 35 or more and 90 / 10 or less. When the mass ratio of the structural units derived from the aliphatic diisocyanate to the structural units derived from the alicyclic diisocyanate is equal to or greater than the above lower limit, a decrease in flexibility when formed into a coating film can be more effectively prevented, while when the mass ratio is equal to or less than the above upper limit, the hardness when formed into a coating film can be further improved.

[0196] (Polyol) The polyisocyanate is preferably derived from the above-mentioned diisocyanate and a polyol (preferably the polyol B) having an average functionality of 3.0 or more and 8.0 or less. This allows the average number of isocyanate groups in the polyisocyanate to be increased. In the polyisocyanate, urethane groups are formed by the reaction between the hydroxyl groups of the polyol and the isocyanate groups of the diisocyanate monomer.

[0197] The average number of functional groups of the polyol is preferably 3.0 or more and 8.0 or less, more preferably 3 or more and 6 or less, even more preferably 3 or more and 5 or less, and particularly preferably 3 or 4. The average number of functional groups of the polyol here refers to the number of hydroxyl groups present in one molecule of the polyol.

[0198] From the viewpoint of improving the hardness and strength of the coating film, the number average molecular weight of the polyol is preferably 100 or more and 1,000 or less, preferably 100 or more and 900 or less, more preferably 100 or more and 600 or less, more preferably 100 or more and 570 or less, even more preferably 100 or more and 500 or less, even more preferably 100 or more and 400 or less, particularly preferably 100 or more and 350 or less, and most preferably 100 or more and 250 or less. When the number-average molecular weight of the polyol is within the above range, the blocked polyisocyanate composition has excellent low-temperature curing properties when formed into a coating film, and is particularly excellent in hardness and strength. The number-average molecular weight Mn of the polyol is, for example, the number-average molecular weight measured by GPC using polystyrene as the standard.

[0199] Examples of such polyols include trimethylolpropane, glycerol, and polycaprolactone polyols derived from trihydric or higher polyhydric alcohols and ε-caprolactone. Examples of commercially available polycaprolactone polyols include those similar to those in the second embodiment.

[0200] (Production of polyisocyanates) The polyisocyanate can be produced in the same manner as in the second embodiment. Furthermore, an antioxidant or an ultraviolet absorber may be added to the resulting polyisocyanate, for example, for the purpose of suppressing coloration during storage. As the antioxidant or ultraviolet absorber, one of the antioxidants or ultraviolet absorbers described in the second embodiment may be used alone, or two or more of them may be used in combination. The amount of these added is preferably 10 ppm by mass or more and 500 ppm by mass or less, relative to the mass of the polyisocyanate.

[0201] (average number of isocyanate groups in polyisocyanate) The average number of isocyanate groups in the polyisocyanate is preferably 2 or more from the viewpoint of improving the low-temperature curing property when formed into a resin film, and from the viewpoint of achieving both the low-temperature curing property when formed into a resin film and compatibility with the polyvalent hydroxy compound, it is more preferably 3 to 20, even more preferably 3.2 to 10, particularly preferably 3.5 to 8, and most preferably 4.2 to 6. The average number of isocyanate groups in the polyisocyanate can be determined by the method described in the second embodiment.

[0202] [Blocking agent] The blocking agent used in producing the blocked polyisocyanate preferably contains a malonic acid ester having a secondary alkyl group or a malonic acid ester having a primary alkyl group, and a malonic acid ester having a tertiary alkyl group, and more preferably contains a malonic acid ester having a secondary alkyl group and a malonic acid ester having a tertiary alkyl group. The blocking agent may contain one type of each of the malonic acid ester having a secondary alkyl group, the malonic acid ester having a primary alkyl group, and the malonic acid ester having a tertiary alkyl group, or a combination of two or more types. There are no particular limitations on the malonic acid ester having a primary alkyl group, the malonic acid ester having a secondary alkyl group, and the malonic acid ester having a tertiary alkyl group, but the same malonic acid esters as those in the first embodiment can be used.

[0203] (Other blocking agents) The blocking agent used in producing the blocked polyisocyanate may further contain other blocking agents in addition to the malonic acid ester having a secondary alkyl group and the malonic acid ester having a tertiary alkyl group, as long as they do not impair the storage stability of the resin composition or the low-temperature curing property of the resin film. As the other blocking agents, those described in the first embodiment can be used.

[0204] (Content of malonic acid esters with secondary alkyl groups and malonic acid esters with tertiary alkyl groups) With respect to the total molar amount of all blocking agents used in the production of the blocked polyisocyanate, the content of the malonic acid ester having a secondary alkyl group and the malonic acid ester having a tertiary alkyl group is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, particularly preferably 95 mol% or more, and most preferably 100 mol%. When the content of the malonic acid ester having a secondary alkyl group and the malonic acid ester having a tertiary alkyl group is within the above range, the low-temperature curing property of the resin film can be further improved.

[0205] [Nonionic compounds] The blocked polyisocyanate contained in the blocked polyisocyanate composition of the present embodiment may have a portion of its isocyanate groups modified with a nonionic compound, i.e., the blocked polyisocyanate may have a structural unit derived from a nonionic compound introduced into a portion of its isocyanate groups. As the nonionic compound, the same compounds as those in the second embodiment can be used.

[0206] From the viewpoint of the aqueous dispersion stability of the blocked polyisocyanate composition, the lower limit of the amount of constitutional units derived from a nonionic compound added to the blocked polyisocyanate (hereinafter, may be referred to as the "nonionic compound content") is preferably 0.1 mass %, more preferably 0.15 mass %, even more preferably 0.2 mass %, and particularly preferably 0.25 mass %, relative to the mass of the solid content of the blocked polyisocyanate composition. Furthermore, from the viewpoint of the water resistance of the resulting resin film, the upper limit of the content of the nonionic compound is preferably 55 mass%, more preferably 50 mass%, even more preferably 48 mass%, and particularly preferably 44 mass%, relative to the mass of the solid content of the blocked polyisocyanate composition. That is, the content of the nonionic compound is preferably 0.1 mass % or more and 55 mass % or less, more preferably 0.15 mass % or more and 50 mass % or less, even more preferably 0.20 mass % or more and 48 mass % or less, and particularly preferably 0.25 mass % or more and 44 mass % or less, relative to the mass of the solid content of the blocked polyisocyanate composition. When the content of the nonionic compound is within the above range, the blocked polyisocyanate composition disperses better in water, and a homogeneous film tends to be obtained.

[0207] From the viewpoint of suppressing a decrease in the hardness and strength of the resulting resin film, the amount of the nonionic compound added to the blocked polyisocyanate, expressed as a molar ratio, relative to 100 mol% of the isocyanate groups in the raw material polyisocyanate, is preferably 0.05 mol% or more and 15 mol% or less, more preferably 0.10 mol% or more and 12 mol% or less, even more preferably 0.10 mol% or more and 9 mol% or less, even more preferably 0.10 mol% or more and 6 mol% or less, and most preferably 0.15 mol% or more and 4 mol% or less.

[0208] [Other hydrophilic compounds] At least a portion of the blocked polyisocyanate may further have a structural unit derived from a hydrophilic compound other than a nonionic compound, that is, a hydrophilic group other than a nonionic hydrophilic group.

[0209] The other hydrophilic compound is a compound having a hydrophilic group other than the nonionic hydrophilic group. In addition to the hydrophilic group other than the nonionic hydrophilic group, the other hydrophilic compound preferably has one or more active hydrogen groups per molecule of the other hydrophilic compound for reacting with at least one isocyanate group of the polyisocyanate. Specific examples of the active hydrogen group include a hydroxyl group, a mercapto group, a carboxylic acid group, an amino group, and a thiol group.

[0210] Examples of other hydrophilic compounds include cationic compounds and anionic compounds. These hydrophilic compounds may be used alone or in combination of two or more. Among them, anionic compounds are preferred as other hydrophilic compounds from the viewpoint of suppressing a decrease in the hardness and strength of the resulting resin film and from the viewpoint of improving emulsifiability. As the cationic compound and the anionic compound, those described in the second embodiment can be used.

[0211] <Other components> The blocked polyisocyanate composition of this embodiment may further contain additives such as a solvent in addition to the blocked polyisocyanate. As the solvent, those described in the first embodiment can be used.

[0212] <Method for producing blocked polyisocyanate composition> The method for producing the blocked polyisocyanate composition of the present embodiment is not particularly limited, but the following two methods can be mentioned, similar to the blocking reaction between polyisocyanate and a blocking agent in the second embodiment. 1) A method of reacting the polyisocyanate with the malonic acid ester having a tertiary alkyl group, and the malonic acid ester having a secondary alkyl group or the malonic acid ester having a primary alkyl group. 2) A method in which the polyisocyanate is reacted with at least one blocking agent selected from the group consisting of the malonic acid ester having a tertiary alkyl group, the malonic acid ester having a secondary alkyl group, and the malonic acid ester having a primary alkyl group, and an alcohol having a chain alkyl group is added to the resulting reaction product to introduce an alkyl group derived from the alcohol by transesterification of the terminal ester moiety of the reaction product.

[0213] Of the two methods above, method 2) is preferred, taking into consideration the ease of the process and the ease of controlling the molar ratio of structural unit (II) / structural unit (I).

[0214] The blocking reaction between the polyisocyanate and the blocking agent can be carried out regardless of the presence or absence of a solvent, and a blocked polyisocyanate is obtained. The blocking agent may be one of a malonic acid ester having a primary alkyl group, a malonic acid ester having a secondary alkyl group, and a malonic acid ester having a tertiary alkyl group, or two or more of them may be used in combination. The amount of the blocking agent added may usually be 80 mol % or more and 200 mol % or less, and preferably 90 mol % or more and 150 mol % or less, based on the total molar amount of isocyanate groups.

[0215] Furthermore, in the blocking agent to be added, the molar ratio of the structural units derived from a malonate ester having a secondary alkyl group to the structural units derived from a malonate ester having a tertiary alkyl group [(malonate ester having a secondary alkyl group) / (malonate ester having a tertiary alkyl group)], and the molar ratio of the structural units derived from a malonate ester having a primary alkyl group to the structural units derived from a malonate ester having a tertiary alkyl group [(malonate ester having a primary alkyl group) / (malonate ester having a tertiary alkyl group)] are each 4 / 96 or more and 96 / 4 or less, preferably 5 / 95 or more and 95 / 5 or less, more preferably 7 / 93 or more and 93 / 7 or less, even more preferably 10 / 90 or more and 90 / 10 or less, even more preferably 20 / 80 or more and 85 / 15 or less, particularly preferably 30 / 70 or more and 85 / 15 or less, and most preferably 35 / 65 or more and 85 / 15. When the molar ratio is equal to or greater than the above lower limit, the storage stability of the aqueous resin composition can be improved, and when the molar ratio is equal to or less than the above upper limit, the low-temperature curing property of the resin film can be improved.

[0216] When a solvent is used, it is sufficient to use a solvent that is inactive to isocyanate groups. When a solvent is used, the content of nonvolatile components derived from the polyisocyanate and the blocking agent relative to 100 parts by mass of the blocked polyisocyanate composition is as described in the second embodiment.

[0217] In the blocking reaction, organic metal salts of tin, zinc, lead, etc., tertiary amine compounds, alcoholates of alkali metals such as sodium, etc., may be used as catalysts. The amount of catalyst added and the blocking reaction temperature are as described in the second embodiment. After the blocking reaction, a neutralization treatment may be carried out by adding an acidic compound, etc. As the acidic compound, the same compounds as those in the first or second embodiment can be used.

[0218] When a hydrophilic compound containing a nonionic compound is used, the polyisocyanate, the blocking agent, and the hydrophilic compound are reacted with each other. The reaction of the polyisocyanate with the hydrophilic compound containing the nonionic compound and the reaction of the polyisocyanate with the blocking agent can be carried out simultaneously, or one of the reactions can be carried out in advance before the second or subsequent reaction is carried out. Among these, it is preferable to carry out the reaction of the polyisocyanate with the hydrophilic compound first to obtain a hydrophilic compound-modified polyisocyanate modified with the hydrophilic compound, and then to react the obtained hydrophilic compound-modified polyisocyanate with the blocking agent.

[0219] The reaction between the polyisocyanate and the hydrophilic compound can be carried out in the same manner as in the second embodiment. The reaction between the hydrophilic compound-modified polyisocyanate and the blocking agent can be carried out in the same manner as in the blocking reaction between the polyisocyanate and the blocking agent described above.

[0220] When the polyisocyanate is produced by the above method 2), the blocking reaction is followed by an ester exchange reaction. As the alcohol having a chain alkyl group used in the transesterification reaction in method 2), the same alcohols as those in the first embodiment can be used. The chain alkyl group of the alcohol may be the same as or different from that of the blocking agent. When the chain alkyl group is different from that of the blocking agent, it is preferable to use a monoalcohol having a chain alkyl group with a different number of alkyl substitutions than that of the blocking agent. Specifically, for example, when a single malonic acid ester having a secondary alkyl group is used as the blocking agent, a monoalcohol having a tertiary alkyl group can be used.

[0221] In the case of producing by the method 2), it is preferable to remove the generated alcohol or the residual added alcohol during or after the transesterification reaction by distillation under normal pressure or reduced pressure. Among these, in order to efficiently proceed with the transesterification reaction, it is preferable to remove the generated alcohol by performing an operation such as distillation during the transesterification reaction. In this case, in order to efficiently remove the alcohol component generated by the transesterification reaction, it is more preferable that the alcohol component to be added has a boiling point higher than that of the generated alcohol component.

[0222] The transesterification reaction can generally be carried out at a temperature of 0° C. or higher and 150° C. or lower, preferably 30° C. or higher and 120° C. or lower, and more preferably 50° C. or higher and 100° C. When the temperature of the transesterification reaction is equal to or higher than the lower limit, the reaction rate can be further increased, and when the temperature is equal to or lower than the upper limit, side reactions can be further suppressed.

[0223] The molar ratio of the structural unit (II) to the structural unit (I) can be controlled by adjusting the molar ratio of the alcohol added to the blocked isocyanate group, or by adjusting the transesterification reaction temperature and transesterification reaction time, or by distilling off the generated alcohol, etc.

[0224] The amount of the alcohol component in the blocked polyisocyanate composition is preferably 0.05 to 41 parts by mass, more preferably 0.1 to 30 parts by mass, and even more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the solids content of the blocked polyisocyanate composition. When the amount of the alcohol component is at least the above lower limit, the storage stability of the paint is improved, and when it is at most the above upper limit, thickening of the aqueous paint during formulation can be suppressed.

[0225] <Characteristics of Blocked Polyisocyanate Composition> [Weight average molecular weight Mw] The weight average molecular weight Mw of the blocked polyisocyanate composition of this embodiment is the same as that of the second embodiment.

[0226] ≪Resin composition≫ The resin composition of this embodiment contains the blocked polyisocyanate composition of the first, second, or third embodiment and a polyvalent hydroxy compound. The resin composition of this embodiment can also be said to be a one-component resin composition containing a curing agent component and a main component.

[0227] The resin composition of the present embodiment has good storage stability, and when formed into a coating film, has excellent curability at a low temperature of about 80°C, hardness, and strength. Furthermore, the resin composition of the present embodiment has excellent storage stability when made into an aqueous resin composition, and is therefore particularly suitable for use as an aqueous resin composition. The components of the resin composition of this embodiment will be described in detail below.

[0228] <Polyhydroxy compounds> In this specification, the term "polyhydroxy compound" refers to a compound having at least two hydroxy groups (hydroxyl groups) in one molecule, and is also called a "polyol." Specific examples of the polyhydric hydroxy compound include aliphatic hydrocarbon polyols, polyether polyols, polyester polyols, epoxy resins, fluorine-containing polyols, and acrylic polyols. Among these, the polyhydric hydroxy compound is preferably a polyester polyol, a fluorine-containing polyol or an acrylic polyol.

[0229] [Aliphatic hydrocarbon polyols] Examples of the aliphatic hydrocarbon polyols include hydroxyl-terminated polybutadiene and hydrogenated products thereof.

[0230] [Polyether polyols] Examples of the polyether polyols include those obtained by any of the following methods (1) to (3). (1) Polyether polyols or polytetramethylene glycols obtained by adding alkylene oxides, either singly or in mixture, to polyhydric alcohols, either singly or in mixture. (2) Polyether polyols obtained by reacting alkylene oxide with a polyfunctional compound. (3) Polymer polyols obtained by polymerizing acrylamide or the like using the polyether polyols obtained in (1) or (2) as a medium. Examples of the polyhydric alcohol include glycerol and propylene glycol. Examples of the alkylene oxide include ethylene oxide and propylene oxide. Examples of the polyfunctional compound include ethylenediamine and ethanolamines.

[0231] [Polyester polyols] Examples of the polyester polyols include the following polyester polyols (1) and (2). (1) Polyester polyol resins obtained by the condensation reaction of a dibasic acid, either alone or in a mixture of two or more kinds, with a polyhydric alcohol, either alone or in a mixture of two or more kinds. (2) Polycaprolactones obtained by ring-opening polymerization of ε-caprolactone with polyhydric alcohols. Examples of the dibasic acid include succinic acid, adipic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid, terephthalic acid, 1,4-cyclohexanedicarboxylic acid, and other carboxylic acids. Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, trimethylpentanediol, cyclohexanediol, trimethylolpropane, glycerol, pentaerythritol, 2-methylolpropanediol, and ethoxylated trimethylolpropane.

[0232] [Epoxy resins] Examples of the epoxy resins include novolac-type epoxy resins, β-methylepicro-type epoxy resins, cyclic oxirane-type epoxy resins, glycidyl ether-type epoxy resins, glycol ether-type epoxy resins, epoxy-type aliphatic unsaturated compounds, epoxidized fatty acid esters, ester-type polycarboxylic acids, aminoglycidyl-type epoxy resins, halogenated epoxy resins, and resorcinol-type epoxy resins, as well as resins obtained by modifying these epoxy resins with amino compounds, polyamide compounds, or the like.

[0233] [Fluorine-containing polyols] Examples of the fluorine-containing polyols include copolymers of fluoroolefins, cyclohexyl vinyl ethers, hydroxyalkyl vinyl ethers, and monocarboxylic acid vinyl esters, which are disclosed in Reference Document 1 (JP-A-57-34107) and Reference Document 2 (JP-A-61-275311), etc.

[0234] [Acrylic polyols] The acrylic polyols can be obtained, for example, by polymerizing a polymerizable monomer having one or more active hydrogen atoms in one molecule, or by copolymerizing a polymerizable monomer having one or more active hydrogen atoms in one molecule with, as needed, another monomer copolymerizable with the polymerizable monomer.

[0235] Examples of the polymerizable monomer having one or more active hydrogen atoms in one molecule include the following (i) to (iii), which may be used singly or in combination of two or more. (i) Acrylic acid esters having active hydrogen, such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 2-hydroxybutyl acrylate. (ii) Methacrylates having active hydrogen, such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, and 2-hydroxybutyl methacrylate. (iii) (meth)acrylic acid esters having polyvalent active hydrogen, such as acrylic acid monoester or methacrylic acid monoester of glycerol, and acrylic acid monoester or methacrylic acid monoester of trimethylolpropane.

[0236] Examples of other monomers copolymerizable with the polymerizable monomer include the following (i) to (v), which may be used singly or in combination of two or more. (i) Acrylic acid esters such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate. (ii) Methacrylates such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate, and glycidyl methacrylate. (iii) Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, and itaconic acid. (iv) Unsaturated amides such as acrylamide, N-methylolacrylamide, and diacetoneacrylamide. (v) Styrene, vinyl toluene, vinyl acetate, acrylonitrile, etc.

[0237] Other examples include acrylic polyols obtained by copolymerizing polymerizable ultraviolet-stable monomers disclosed in Reference 3 (JP-A No. 1-261409) and Reference 4 (JP-A No. 3-006273).

[0238] Specific examples of the polymerizable ultraviolet-stable monomer include 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, and 2-hydroxy-4-(3-methacryloxy-2-hydroxypropoxy)benzophenone.

[0239] For example, the above-mentioned monomer components are solution polymerized in the presence of a known radical polymerization initiator such as a peroxide or an azo compound, and the resulting solution is diluted with an organic solvent or the like as necessary to obtain an acrylic polyol.

[0240] Aqueous-based acrylic polyols can be produced by known methods such as solution polymerization of an olefinically unsaturated compound followed by conversion into an aqueous phase, emulsion polymerization, etc. In this case, water solubility or water dispersibility can be imparted by neutralizing the acidic moiety of a carboxylic acid-containing monomer such as acrylic acid or methacrylic acid, or a sulfonic acid-containing monomer, with an amine or ammonia.

[0241] [Hydroxyl value and acid value of polyhydroxy compounds] The hydroxyl value of the polyvalent hydroxy compound contained in the resin composition of this embodiment is preferably 5 mgKOH / g or more and 300 mgKOH / g or less, more preferably 10 mgKOH / g or more and 280 mgKOH / g or less, and even more preferably 30 mgKOH / g or more and 250 mgKOH / g or less. When the hydroxyl value of the polyvalent hydroxy compound is within the above range, a resin film having excellent physical properties such as tensile strength can be obtained. Specifically, when the hydroxyl group content of the polyvalent hydroxy compound is equal to or greater than the above lower limit, the crosslink density of the urethane formed by the reaction with the polyisocyanate is increased, making it easier for the urethane bond to function. On the other hand, when the hydroxyl group content of the polyvalent hydroxy compound is equal to or less than the above upper limit, the crosslink density is not increased too much, resulting in better mechanical properties of the resin film. The hydroxyl value of the polyvalent hydroxy compound is measured, for example, by potentiometric titration and calculated as a value relative to the solid content of the polyvalent hydroxy compound.

[0242] [Glass transition temperature Tg of polyhydroxy compounds] The glass transition temperature Tg of the polyvalent hydroxy compound contained in the resin composition of this embodiment is preferably 0°C or higher and 100°C or lower, more preferably 0°C or higher and 90°C or lower, even more preferably 0°C or higher and 80°C or lower, and particularly preferably 5°C or higher and 70°C or lower. When the glass transition temperature of the polyvalent hydroxy compound is within the above range, a resin film with superior tensile strength can be obtained. The glass transition temperature of the polyvalent hydroxy compound can be measured, for example, using the method described in the examples below.

[0243] [Weight-average molecular weight Mw of polyhydroxy compound] The weight average molecular weight Mw of the polyhydroxy compound is 5.0 × 10 3 Over 2.0 x 10 5 Preferably, it is 5.0 x 10 or less. 3 Over 1.5 x 10 5 More preferably, it is 5.0×10 or less. 3 Over 1.0 x 10 5It is more preferable that the weight average molecular weight Mw of the polyvalent hydroxy compound is within the above range, thereby obtaining a resin film having excellent physical properties such as tensile strength. The weight average molecular weight Mw of the polyvalent hydroxy compound can be measured, for example, by the method described in the examples below.

[0244] [NCO / OH] The molar equivalent ratio (NCO / OH) of the isocyanate groups of the blocked polyisocyanate composition to the hydroxyl groups of the polyvalent hydroxy compound contained in the resin composition of this embodiment is determined depending on the required physical properties of the resin film, but is usually 0.01 or more and 22.5 or less.

[0245] [Blocked polyisocyanate composition content] In the resin composition of this embodiment, the content of the blocked polyisocyanate may be any amount such that the molar equivalent ratio of the isocyanate groups of the blocked polyisocyanate to the hydroxyl groups of the polyhydroxy compound falls within the above-mentioned range. For example, the content is preferably 1 part by mass or more and 200 parts by mass or less, more preferably 5 parts by mass or more and 180 parts by mass or less, and even more preferably 10 parts by mass or more and 150 parts by mass or less, per 100 parts by mass of the polyhydroxy compound. Having the content of the blocked polyisocyanate within the above-mentioned range allows for the production of a resin film with superior physical properties such as tensile strength. The content of the blocked polyisocyanate can be calculated from the blend amount, or can be calculated by identifying and quantifying the blocked polyisocyanate using nuclear magnetic resonance (NMR) and gas chromatography / mass spectrometry (GC / MS).

[0246] <Other additives> The resin composition of the present embodiment may further contain other additives. Examples of other additives include curing agents capable of reacting with crosslinkable functional groups in the polyhydric hydroxy compound, curing catalysts, solvents, pigments (extender pigments, colored pigments, metallic pigments, etc.), ultraviolet absorbers, light stabilizers, radical stabilizers, anti-yellowing agents that suppress coloring during the baking process, coating surface conditioners, flow conditioners, pigment dispersants, antifoaming agents, thickeners, film-forming aids, etc.

[0247] Examples of the curing agent include melamine resins, urea resins, epoxy group-containing compounds or resins, carboxyl group-containing compounds or resins, acid anhydrides, alkoxysilane group-containing compounds or resins, and hydrazide compounds.

[0248] The curing catalyst may be a basic compound or a Lewis acid compound. Examples of the basic compound include metal hydroxides, metal alkoxides, metal carboxylates, metal acetylacetinates, hydroxides of onium salts, onium carboxylates, halides of onium salts, metal salts of active methylene compounds, onium salts of active methylene compounds, aminosilanes, amines, phosphines, etc. The onium salt is preferably an ammonium salt, a phosphonium salt, or a sulfonium salt. Examples of the Lewis acid compound include organotin compounds, organozinc compounds, organotitanium compounds, and organozirconium compounds.

[0249] Examples of the solvent include the same solvents as those exemplified for the blocked polyisocyanate composition.

[0250] In addition, known pigments (extender pigments, colored pigments, metallic pigments, etc.), ultraviolet absorbers, light stabilizers, radical stabilizers, anti-yellowing agents that suppress coloring during the baking process, coating surface conditioners, flow conditioners, pigment dispersants, antifoaming agents, thickeners, and film-forming aids can be appropriately selected and used.

[0251] <Method of manufacturing resin composition> The resin composition of the present embodiment can be used as either a solvent-based or water-based resin composition, but is preferably used as a water-based resin composition.

[0252] When producing an aqueous resin composition (waterborne resin composition), first, additives such as a curing agent capable of reacting with the crosslinkable functional group in the polyhydroxy compound, a curing catalyst, a solvent, pigments (extender pigments, colored pigments, metallic pigments, etc.), UV absorbers, light stabilizers, radical stabilizers, anti-yellowing agents that suppress discoloration during the baking process, coating surface conditioners, flow control agents, pigment dispersants, antifoaming agents, thickeners, and film-forming aids are added to the polyhydroxy compound or its aqueous dispersion or solution, as needed. Next, the blocked polyisocyanate composition or its aqueous dispersion is added as a curing agent, and if necessary, water or a solvent is further added to adjust the viscosity. Next, the mixture is forcedly stirred with a stirring device to obtain an aqueous resin composition (waterborne resin composition).

[0253] When producing a solvent-based resin composition, first, additives such as a curing agent capable of reacting with the crosslinkable functional group in the polyhydroxy compound, a curing catalyst, a solvent, pigments (extender pigments, colored pigments, metallic pigments, etc.), UV absorbers, light stabilizers, radical stabilizers, anti-yellowing agents that suppress discoloration during the baking process, coating surface conditioners, flow conditioners, pigment dispersants, defoamers, thickeners, and film-forming aids are added to the polyhydroxy compound or its solvent dilution, as needed. Next, the above-mentioned blocked polyisocyanate composition is added as a curing agent, and if necessary, a solvent is further added to adjust the viscosity. Next, the mixture is stirred by hand or using a stirring device such as a mixer to obtain a solvent-based resin composition.

[0254] <Resin film> The resin film of this embodiment is formed by curing the resin composition described above. The resin film of this embodiment has excellent curability, hardness, and strength at low temperatures of about 80°C.

[0255] The resin film of this embodiment is obtained by applying the above-mentioned resin composition to a substrate using a known method such as roll coating, curtain flow coating, spray coating, bell coating, or electrostatic coating, and then curing it by heating.

[0256] From the viewpoint of energy saving and heat resistance of the substrate, the heating temperature is preferably about 70°C or more and about 120°C or less, more preferably about 70°C or more and about 110°C or less, and even more preferably about 75°C or more and about 100°C or less. From the viewpoint of energy saving and heat resistance of the substrate, the heating time is preferably from about 1 minute to about 60 minutes, more preferably from about 2 minutes to about 40 minutes.

[0257] The substrate is not particularly limited, and examples thereof include outer panels of automobile bodies such as passenger cars, trucks, motorcycles, and buses; automobile parts such as bumpers; outer panels of household electrical appliances such as mobile phones and audio equipment; and various films, among which outer panels of automobile bodies or automobile parts are preferred.

[0258] The material of the substrate is not particularly limited, and examples thereof include metal materials such as iron, aluminum, brass, copper, tinplate, stainless steel, zinc-plated steel, and zinc alloy (Zn-Al, Zn-Ni, Zn-Fe, etc.)-plated steel; resins such as polyethylene resin, polypropylene resin, acrylonitrile-butadiene-styrene (ABS) resin, polyamide resin, acrylic resin, vinylidene chloride resin, polycarbonate resin, polyurethane resin, and epoxy resin; plastic materials such as various FRPs; inorganic materials such as glass, cement, and concrete; wood; and fibrous materials such as paper and cloth. Of these, metal materials and plastic materials are preferred.

[0259] The substrate may be the surface of the above-mentioned metal material, or the surface of a metal such as a car body molded from the above-mentioned metal material, which has been subjected to a surface treatment such as phosphate treatment, chromate treatment, or composite oxide treatment, and further, may have a coating film formed thereon. The substrate with a coating film formed thereon may be one that has been subjected to a surface treatment as necessary and then a primer coating film formed thereon, for example, a car body on which a primer coating film has been formed using an electrodeposition paint. The substrate may be the surface of the above-mentioned plastic material, or the surface of a plastic such as an automobile part molded from the above-mentioned metal material, which has been subjected to a desired surface treatment. The substrate may also be a combination of a plastic material and a metal material.

[0260] As shown in the examples described below, the resin film of this embodiment is a 40 μm thick resin film obtained by heating and curing the resin composition at 80° C. for 30 minutes. After storing the resin film at 23° C. for one week, the resin film preferably has a gel fraction of 82% by mass or more, more preferably 83% by mass or more, even more preferably 84% by mass or more, even more preferably 85% by mass or more, and even more preferably 86% by mass or more. Having a gel fraction equal to or greater than the lower limit mentioned above can improve low-temperature curing properties. The upper limit of the gel fraction is not particularly limited, but can be set to, for example, 100% by mass. The gel fraction can be measured, for example, by the method described in the examples described below.

[0261] As shown in the examples described below, the resin film of this embodiment is a 40 μm thick resin film obtained by heating and curing the resin composition on glass at 80° C. for 30 minutes. The Konig hardness at 23° C. of the resulting resin film is preferably 40 or more, more preferably 45 or more, even more preferably 50 or more, even more preferably 55 or more, and even more preferably 60 or more. A Konig hardness equal to or greater than the lower limit mentioned above can result in a resin film with better hardness. On the other hand, the upper limit of the Konig hardness is not particularly limited, but can be set to, for example, 160. A specific method for measuring the Konig hardness can be, for example, the method described in the examples described below.

[0262] As shown in the examples described below, the resin film of this embodiment is a 40 μm thick resin film obtained by heating and curing the resin composition at 80° C. for 30 minutes, and the maximum tensile stress at 23° C. is preferably 10.0 MPa or more, more preferably 15 MPa or more, even more preferably 20 MPa or more, and particularly preferably 25 MPa or more. Having a maximum tensile stress at 23° C. equal to or greater than the lower limit mentioned above allows for a resin film with better strength. Meanwhile, the upper limit of the maximum tensile stress at 23° C. is not particularly limited, but can be set to, for example, 100 MPa. A specific method for measuring the maximum tensile stress at 23° C. can be, for example, the method described in the examples described below.

[0263] The resin film of this embodiment has excellent low-temperature curing properties, and is therefore suitable for use in products in various fields where energy conservation is required, and as a coating film for materials with low heat resistance.

[0264] <Laminate> The laminate of this embodiment includes two or more resin films of different compositions. The thickness of each resin film is 1 μm or more and 50 μm or less. By including the resin film, the laminate of this embodiment has excellent low-temperature curing properties.

[0265] The laminate of this embodiment may also include two or more layers of the above resin films having the same composition.

[0266] The laminate of the present embodiment is formed by laminating various coating films, including the above-mentioned resin film, on an adherend. Examples of the adherend include glass, various metals, porous materials, materials with various coatings, cured sealants, rubbers, leather, fibers, nonwoven fabrics, resin films and plates, ultraviolet-curable acrylic resin layers, and layers made of inks. Examples of the various metals include aluminum, iron, galvanized steel, copper, and stainless steel. Examples of the porous material include wood, paper, mortar, and stone. Examples of the various coatings include fluorine coating, urethane coating, and acrylic urethane coating. Examples of the cured sealant include silicone-based, modified silicone-based, and urethane-based sealants. Examples of the rubbers include natural rubber and synthetic rubber. Examples of the leathers include natural leather and artificial leather. Examples of the fibers include plant fibers, animal fibers, carbon fibers, and glass fibers. Examples of resins that can be used as raw materials for the resin films and plates include polyvinyl chloride, polyester, acrylic, polycarbonate, triacetyl cellulose, polyolefin, and the like. Examples of the inks include printing inks and UV inks.

[0267] The laminate of this embodiment can be obtained by coating the above-mentioned resin compositions having different compositions onto an adherend using a known method such as roll coating, curtain flow coating, spray coating, bell coating, or electrostatic coating, and then heating and curing the layers, or by coating all of the layers and then heating and curing them all at once.

[0268] The laminate of this embodiment may include, in addition to the resin film, other layers made of known components, such as a primer layer, an adhesive layer, and a decorative layer. [Example]

[0269] The present embodiment will be described in more detail below based on examples and comparative examples, but the present embodiment is not limited to the following examples in any way.

[0270] <Test items> The blocked polyisocyanate compositions obtained in the examples and comparative examples were subjected to measurement and evaluation of various physical properties according to the methods described below.

[0271] [Physical Properties 1] (Isocyanate group (NCO) content) In order to measure the NCO content of the polyisocyanate, the polyisocyanate before being blocked with a blocking agent was used as a measurement sample. First, 2 g to 3 g of the measurement sample was weighed out into a flask (Wg). Next, 20 mL of toluene was added to dissolve the measurement sample. Next, 20 mL of a 2 N toluene solution of di-n-butylamine was added, mixed, and left at room temperature for 15 minutes. Next, 70 mL of isopropyl alcohol was added and mixed. Next, this liquid was titrated with a 1 N hydrochloric acid solution (factor F) as an indicator. The obtained titration value was V2 mL. Next, the titration value obtained without the polyisocyanate sample was V1 mL. Next, the isocyanate group (NCO) content (mass%) of the polyisocyanate was calculated using the following formula. Isocyanate group (NCO) content (mass%) = (V1 - V2) x F x 42 / (W x 1000) x 100

[0272] [Physical Properties 2] (Number average molecular weight and weight average molecular weight) The number average molecular weight and weight average molecular weight are those measured by gel permeation chromatography (GPC) using the following equipment, using polystyrene standards. In order to measure the number average molecular weight of the polyisocyanate, the polyisocyanate before being blocked with a blocking agent was used as a measurement sample. The weight average molecular weight was measured using the blocked polyisocyanate composition or the polyhydroxy compound as it was. The measurement conditions are shown below.

[0273] (Measurement conditions) Equipment: Tosoh Corporation, HLC-802A Column: Tosoh Corporation, G1000HXL x 1 G2000HXL x 1 G3000HXL x 1 Carrier: Tetrahydrofuran Detection method: differential refractometer

[0274] [Physical Properties 3] (average number of isocyanate groups) The average number of isocyanate groups (average NCO number) of the polyisocyanate was calculated by the following formula. In the formula, "Mn" is the number average molecular weight of the polyisocyanate before blocking with a blocking agent, and the value measured in "Property 2" above was used. "NCO content" is the isocyanate group content of the polyisocyanate measured before blocking with a blocking agent, and the value calculated in "Property 1" above was used. Average number of isocyanate groups = (Mn × NCO content × 0.01) / 42

[0275] [Physical Properties 4] (Solid content of blocked polyisocyanate composition) The solid content of the blocked polyisocyanate composition was determined as follows. First, an aluminum dish with a bottom diameter of 38 mm was precisely weighed. Then, approximately 1 g of the blocked polyisocyanate composition produced in the Examples and Comparative Examples was placed on the aluminum dish and precisely weighed (W1). The blocked polyisocyanate composition was then adjusted to a uniform thickness. The blocked polyisocyanate composition placed on the aluminum dish was then kept in an oven at 105°C for 1 hour. After the aluminum dish returned to room temperature, the blocked polyisocyanate composition remaining on the aluminum dish was precisely weighed (W2). The solids content (% by mass) of the blocked polyisocyanate composition was then calculated using the following formula: Solid content of blocked polyisocyanate composition (mass%) = W2 / W1 × 100

[0276] [Physical Properties 5] (Hydroxyl value) The hydroxyl value of the polyhydroxy compound was measured and calculated by potentiometric titration. The hydroxyl value is a value relative to the solid content of the polyhydroxy compound.

[0277] [Physical Properties 6] (glass transition temperature Tg) The glass transition temperature of the polyhydroxy compound was measured by vacuum-drying the polyhydroxy compound solution after removing the organic solvent and water under reduced pressure, using a differential scanning calorimetry (DSC) analyzer at a heating rate of 5°C / min.

[0278] [Physical Properties 7] (The molar ratio of the hydroxy group contained in polyol A to the structural unit (I) (OH / structural unit (I)) The molar ratio of the content (mol) of hydroxy groups contained in polyol A in the blocked polyisocyanate composition to the structural unit (I) was calculated from the blend amounts of polyol A and blocking agent. Alternatively, the content (mol) of hydroxy groups contained in polyol A is measured by gas chromatography / mass spectrometry (GC / MS), and the content (mol) of structural unit (I) is measured by 13 The molar amounts were calculated by measuring with C-NMR, and the molar ratios were determined.

[0279] (Measurement conditions) (Hydroxy group content (mol) in polyol A) 2-Ethylhexanol was added to the blocked polyisocyanate composition in an amount 5 times the molar amount of available isocyanate groups in the blocked polyisocyanate composition, and then the mixture was heated at 120°C for 5 hours. The reaction liquid after heating was subjected to gas chromatography / mass spectrometry (GC / MS) to measure the generated polyol A component, and the content (mol) of hydroxy groups contained in polyol A in the blocked polyisocyanate composition was calculated. Equipment: Agilent Technologies, Inc. "Agilent 7890, 5977" Column: Agilent Technologies "HP-5MS" (L 30 m, I.D 0.250 mm, Film 0.25 μm) Carrier gas: Helium Detector: MSD Ionization method: EI Inlet temperature: 320℃ Transfer temperature: 320℃ Oven temperature: 40°C (hold for 5 minutes) → (heat up at 20°C / minute) → 320°C (hold for 10 minutes) Spirit ratio: 1 / 1000 Mass range: m / z 10~800 Injection volume: 0.5μL

[0280] (Content (mol) of structural unit (I)) The content of the structural unit (I) in the blocked polyisocyanate composition is 13 Calculated by C-NMR. Device: JEOL “JEOL-ECZ500(SC)” (product name) Solvent: deuterated chloroform Accumulation count: 5120 times Sample concentration: 50 wt / vol% Chemical shift standard: deuterated chloroform was used as 77.0 ppm.

[0281] [Physical Property 8] Molar ratio of structural unit (I-1) in structural unit (I) The molar ratio of the structural unit (I-1) to the structural unit (I) in the blocked polyisocyanate composition (structural unit (I-1) / structural unit (I)) was calculated using the method shown below. Specifically, we used the JEOL-ECZ500 (SC) (product name) manufactured by JEOL. 13 The total molar amount of the structural unit (I) (including the structural unit (I-1)) and the molar amount of the structural unit (I-1) were calculated by C-NMR measurement, and the molar ratio was determined.

[0282] (Measurement conditions) Device: JEOL “JEOL-ECZ500(SC)” (product name) Solvent: deuterated chloroform Accumulation count: 5120 times Sample concentration: 50 wt / vol% Chemical shift standard: deuterated chloroform was used as 77.0 ppm.

[0283] [Physical Properties 9] (molar ratio of structural unit (II) / structural unit (I)) The molar ratio of the structural unit (II) to the structural unit (I) (structural unit (II) / structural unit (I)) is determined by evaporating the blocked polyisocyanate composition at 50°C or less to remove the solvent and other components, drying under reduced pressure, and then 13 The molar ratio of the structural unit (II) to the structural unit (I) was calculated by measuring the composition ratio of the structural unit (II) to the structural unit (I) by C-NMR.

[0284] (Measurement conditions) Device: JEOL “JEOL-ECZ500(SC)” (product name) Solvent: deuterated chloroform Accumulation count: 5120 times Sample concentration: 50 wt / vol% Chemical shift standard: deuterated chloroform was used as 77.0 ppm.

[0285] [Physical Properties 10] (Monoalcohol content in blocked polyisocyanate) The amount (mass %) of the monoalcohol in the blocked polyisocyanate composition was determined by gas chromatography. Equipment: SHIMADZU GC-2014 Column: Agilent J&W DB-1 (L 30 m, I.D 0.25 mm, Film 1.00 μm) Carrier gas: Helium Detector: FID Inlet temperature: 100℃ Detector temperature: 220℃ Oven temperature: 40°C (hold for 5 minutes) → (heat up at 10°C / minute) → 150°C (hold for 5 minutes) Injection volume: 0.3μL

[0286] [Production of Resin Composition 1-1] The polyhydric hydroxy compound OHP1 and each blocked isocyanate composition were blended so that the ratio of the molar amount of isocyanate groups to the molar amount of hydroxyl groups (isocyanate groups / hydroxyl groups) was 1, and 2-propanol was further blended to adjust the solid content to 35 mass % to obtain a resin composition.

[0287] [Production of Resin Composition 1-2] The polyhydric hydroxy compound OHP1 and each blocked isocyanate composition were blended so that the ratio of the molar amount of isocyanate groups to the molar amount of hydroxyl groups (isocyanate groups / hydroxyl groups) was 1, and butyl acetate was further blended to adjust the solid content to 35 mass % to obtain a resin composition.

[0288] [Rating 1-1] (Storage stability) The resin composition obtained in "Resin Composition Production 1-1" above was measured for initial viscosity and viscosity after storage at 40°C for 10 days (viscometer: RE-85R manufactured by Toki Sangyo Co., Ltd.). Then, the ratio of the viscosity after storage to the initial viscosity was calculated. The storage stability was evaluated from the calculated ratio of the viscosity after storage to the initial viscosity according to the following evaluation criteria.

[0289] (Evaluation criteria) A: The ratio of viscosity after storage to initial viscosity is 2.0 or less B: The ratio of viscosity after storage to initial viscosity is more than 2.0 and 3.0 or less C: Gelation

[0290] [Rating 1-2] (Low temperature curing: gel fraction) The resin composition obtained in "Resin Composition Production 1-2" above was applied to a polypropylene (PP) plate to a dry film thickness of 40 μm, and then heated and dried at 80°C for 30 minutes to obtain a resin film. The obtained resin film was stored at room temperature (23°C) for one week, and the gel fraction was measured. The gel fraction was calculated as a percentage (mass%) obtained by dividing the mass of the undissolved portion of the resin film when immersed in acetone at 23°C for 24 hours by the mass before immersion. A gel fraction of 82 mass% or more was evaluated as good.

[0291] [Rating 1-3] (Konig hardness) The resin composition obtained in "Production of Resin Composition 1-2" above was applied to a glass plate to a dry film thickness of 40 μm, and then heated and dried at 80°C for 30 minutes to obtain a resin film. The resulting resin film was measured for Konig hardness (cycles) in an environment of 23°C using a Konig hardness tester (Pendulum hardness tester from BYK Gardner). A Konig hardness of 40 cycles or more was evaluated as good.

[0292] [Rating 1-4] (Strength: Maximum tensile stress) The resin composition obtained in "Resin Composition Production 1-2" above was applied to a polypropylene (PP) plate to a dry film thickness of 40 μm, and then heated and dried at 80°C for 30 minutes to obtain a resin film. The obtained resin film was cut to a width of 10 mm and a length of 40 mm, set so that the chuck distance was 20 mm, and a tensile test was performed in an environment of 23°C at a speed of 20 mm / min. The maximum point stress at this time was defined as the maximum tensile stress. A maximum tensile stress of 10.0 MPa or more was evaluated as good.

[0293] [Rating 1-5] (Solvent resistance (xylene rubbing test)) The obtained aqueous resin composition was applied to a glass plate to a dry film thickness of 40 μm, and then heated and dried at 85°C for 30 minutes to obtain a resin film. The obtained resin film was stored at room temperature (23°C) for 1 day, and then rubbed 20 times with a cotton swab soaked in xylene at 23°C over a length of 3 cm to observe the state of the resin film. The solvent resistance was evaluated based on the state of the resin film according to the following evaluation criteria. A rating of B or higher was considered to have good solvent resistance. A: Almost no deterioration is observed B: Streaks were observed in some rubbed areas. C: Streaks were observed in the rubbed area, and thinning was observed. D: There were areas where the resin film on the rubbed area was completely dissolved.

[0294] <Synthesis of Polyisocyanate> [Synthesis Example 1-1] (Synthesis of Polyisocyanate P1-1) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by mass of HDI and 5.3 parts by mass of a polyester polyol (polycaprolactone triol) derived from a trihydric alcohol and ε-caprolactone (Daicel Chemical Industries, Ltd., "PLACCEL 303" (trade name), average functionality: 3, number-average molecular weight: 300) under a nitrogen stream. The temperature inside the reactor was maintained at 89°C for 1 hour with stirring to carry out a urethane reaction. The temperature inside the reactor was then maintained at 63°C, and an isocyanuration catalyst, tetramethylammonium caprylate, was added. When the yield reached 52% by mass, phosphoric acid was added to terminate the reaction. The reaction solution was filtered, and unreacted HDI was removed using a thin-film evaporator to obtain an isocyanurate-type polyisocyanate (hereinafter sometimes referred to as "polyisocyanate P1-1"). The NCO content of the obtained polyisocyanate P1-1 was 18.6% by mass, the number average molecular weight was 1220, and the average number of isocyanate groups was 5.4. 1 H-NMR analysis confirmed the presence of isocyanurate groups.

[0295] [Synthesis Example 1-2] (Synthesis of Polyisocyanate P1-2) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 81 parts by mass of HDI, 19 parts by mass of IPDI, and 3.35 parts by mass of trimethylolpropane (average functionality: 3, molecular weight: 134), a trihydric alcohol, under a nitrogen stream. The temperature inside the reactor was maintained at 88°C for 1 hour with stirring to carry out a urethane reaction. The temperature inside the reactor was then maintained at 78°C, and 0.012 parts by mass of the isocyanuration catalyst tetramethylammonium caprylate was added. When the yield reached 44% by mass, phosphoric acid was added to terminate the reaction. The reaction solution was filtered, and unreacted HDI and IPDI were removed using a thin-film evaporator to obtain an isocyanurate-type polyisocyanate (hereinafter sometimes referred to as "polyisocyanate P1-2"). The resulting polyisocyanate P1-2 had an NCO content of 19.0% by mass, a number-average molecular weight of 1170, and an average number of isocyanate groups of 5.3. In addition, the obtained polyisocyanate P1-2 1 H-NMR analysis confirmed the presence of isocyanurate groups.

[0296] [Synthesis Example 1-3] (Synthesis of polyisocyanates P1-3) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 70 parts by mass of HDI, 30 parts by mass of IPDI, and 2.9 parts by mass of trimethylolpropane (average functionality: 3, molecular weight: 134), a trihydric alcohol, under a nitrogen stream. The temperature inside the reactor was maintained at 88°C for 1 hour with stirring to carry out a urethane reaction. The temperature inside the reactor was then maintained at 78°C, and 0.012 parts by mass of the isocyanuration catalyst tetramethylammonium caprylate was added. When the yield reached 44% by mass, phosphoric acid was added to terminate the reaction. The reaction solution was filtered, and unreacted HDI and IPDI were removed using a thin-film evaporator to obtain an isocyanurate-type polyisocyanate (hereinafter sometimes referred to as "Polyisocyanate P1-3"). The resulting polyisocyanate P1-3 had an NCO content of 18.9% by mass, a number-average molecular weight of 1130, and an average number of isocyanate groups of 5.1. In addition, the obtained polyisocyanate P1-3 1H-NMR analysis confirmed the presence of isocyanurate groups.

[0297] [Synthesis Example 1-4] (Synthesis of polyisocyanates P1-4) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by mass of HDI under a nitrogen stream. The temperature inside the reactor was maintained at 60°C while stirring, and 0.095 parts by mass of trimethylbenzylammonium hydroxide was added. After 4.5 hours, when the conversion rate reached 40% by mass, 0.02 parts by mass of phosphoric acid was added to terminate the reaction. The reaction solution was filtered, and unreacted HDI was removed using a thin-film evaporator to obtain an isocyanurate-type polyisocyanate (hereinafter sometimes referred to as "polyisocyanate P1-4"). The NCO content of the obtained polyisocyanate P1-4 was 22.0% by mass, the number-average molecular weight was 655, and the average number of isocyanate groups was 3.43. Regarding the obtained polyisocyanate P1-4, 1 H-NMR analysis confirmed the presence of isocyanurate groups.

[0298] [Synthesis Example 1-5] (Synthesis of Polyisocyanates P1-5) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 600 parts by mass of HDI and 10.8 parts of 1,3-butanediol (a dihydric alcohol) under a nitrogen stream. The temperature inside the reactor was maintained at 90°C for 1 hour while stirring, allowing for a urethane reaction. The temperature inside the reactor was then maintained at 80°C, and 0.03 parts of tetramethylammonium caprylate was added as an isocyanuration catalyst. The refractive index of the reaction solution was measured, and when the yield reached 55%, phosphoric acid was added to terminate the reaction. The reaction solution was filtered, and unreacted HDI was removed using a thin-film evaporator to obtain an isocyanurate-type polyisocyanate (hereinafter sometimes referred to as "polyisocyanate P1-5"). The resulting polyisocyanate P1-5 had an NCO content of 19.3% by mass, a number-average molecular weight of 970, and an average number of isocyanate groups of 4.4. Regarding the resulting polyisocyanate P1-5, 1H-NMR analysis confirmed the presence of isocyanurate groups.

[0299] <Production of Blocked Polyisocyanate Composition> [Example 1-1] (Production of Blocked Polyisocyanate Composition BL-a1-1) A four-neck flask equipped with a thermometer, a stirring blade, and a reflux condenser was mixed with 100 parts by mass of the polyisocyanate P1-1 obtained in Synthesis Example 1-1, 0.59 parts by mass (0.50 mol % relative to 100 mol % of isocyanate groups) of polycaprolactone diol (hereinafter, sometimes referred to as "C1") (manufactured by Daicel Corporation, "Placcel 205UT" (trade name), number average molecular weight 530, average number of functional groups 2), 0.008 parts by mass of 2-ethylhexyl acid phosphate (manufactured by Johoku Chemical Industry Co., Ltd., "JP-508T" (trade name)), and 54.2 parts by mass of dipropylene glycol dimethyl ether (DPDM) under a nitrogen stream, and the mixture was allowed to react at 80°C for 3 hours. The reaction mixture was cooled to 40°C, and diisopropyl malonate (hereinafter sometimes referred to as "B1") was added at 50 mol% relative to 100 mol% of isocyanate groups, and di-tert-butyl malonate (hereinafter sometimes referred to as "B2") was added at 50 mol% relative to 100 mol% of isocyanate groups. Dipropylene glycol dimethyl ether (DPDM) was then added dropwise to adjust the solids content to 60% by mass. Next, 1.1 parts by mass of a methanol solution containing sodium methylate (28% by mass relative to the total mass of the solution) was added dropwise with stirring. The external bath was then adjusted to raise the solution temperature to 47°C, and the blocking reaction was carried out at 47°C for at least 6 hours. After confirming the disappearance of the isocyanate group peaks by infrared spectroscopy (IR), blocked polyisocyanate composition BL-a1-1 was obtained. The resulting blocked polyisocyanate composition BL-a1-1 had a solids content of 60.0% by mass and a weight-average molecular weight of 2.1 x 10. 4 It was.

[0300] [Examples 1-2 to 1-14, 1-17 to 1-21, 1-23, 1-26 and Comparative Examples 1-1 to 1-2] (Production of Blocked Polyisocyanate Compositions BL-a1-2 to BL-a1-14, BL-a1-17 to BL-a1-21, BL-a1-23, BL-a1-26, and BL-b1-1 to BL-b1-2) Each blocked polyisocyanate composition was produced in the same manner as in Example 1-1, except that the types and amounts of polyisocyanate, polyol, and blocking agent were as shown in Tables 1 to 6.

[0301] [Examples 1-15] (Production of Blocked Polyisocyanate Composition BL-a1-15) A four-necked flask equipped with a thermometer, a stirring blade, and a reflux condenser was charged with 100 parts by mass of the polyisocyanate P1-1 obtained in Synthesis Example 1-1, diisopropyl malonate (B1) at 50 mol% relative to 100 mol% of isocyanate groups, and di-tert-butyl malonate (B2) at 50 mol% relative to 100 mol% of isocyanate groups under a nitrogen stream. Dipropylene glycol dimethyl ether (DPDM) was then added dropwise to the mixture to a solids content of 60% by mass. Next, 1.1 parts by mass of a methanol solution containing sodium methylate (28% by mass relative to the total mass of the solution) was added dropwise with stirring, and the external bath was adjusted so that the solution temperature was 47°C. The blocking reaction was carried out at 47°C for 6 hours or more. Subsequently, 0.59 parts by mass of polycaprolactone diol (C1) (manufactured by Daicel Corporation, "Placcel 205UT" (trade name), number average molecular weight 530, average number of functional groups 2) was added, and the external bath was adjusted so that the solution temperature was 80°C. The reaction was carried out for 2 hours to obtain blocked polyisocyanate composition BL-a1-15. The obtained blocked polyisocyanate composition BL-a1-15 had a solids content of 60.1% by mass and a weight average molecular weight of 1.8 x 10 4 It was.

[0302] [Example 1-16] (Production of Blocked Polyisocyanate Composition BL-a1-16) A four-neck flask equipped with a thermometer, a stirring blade, and a reflux condenser was mixed with 100 parts by mass of the polyisocyanate P1-2 obtained in Synthesis Example 1-2, 0.59 parts by mass of polycaprolactone diol (C1) (manufactured by Daicel Corporation, "PLACCEL 205UT" (trade name), number average molecular weight 530, average functionality 2) (0.50 mol % relative to 100 mol % of isocyanate groups), 0.008 parts by mass of 2-ethylhexyl acid phosphate (manufactured by Johoku Chemical Industry Co., Ltd., "JP-508T" (trade name)), and 54.2 parts by mass of dipropylene glycol dimethyl ether (DPDM) under a nitrogen stream, and the mixture was allowed to react at 80°C for 4 hours. The reaction mixture was cooled to 40°C, and diisopropyl malonate (B1) was added at 70 mol% relative to 100 mol% isocyanate groups, and di-tert-butyl malonate (B2) was added at 30 mol% relative to 100 mol% isocyanate groups. Dipropylene glycol dimethyl ether (DPDM) was then added to adjust the solids content to 60% by mass. Next, 1.1 parts by mass of a methanol solution containing sodium methylate (28% by mass relative to the total mass of the solution) was added dropwise with stirring. The external bath was then adjusted to a solution temperature of 47°C, and the blocking reaction was carried out at 47°C for at least 6 hours. After confirming the disappearance of the isocyanate group peaks by infrared spectroscopy (IR), blocked polyisocyanate composition BL-a1-16 was obtained. The resulting blocked polyisocyanate composition BL-a1-16 had a solids content of 60.0% by mass and a weight-average molecular weight of 2.0 x 10. 4 It was.

[0303] [Example 1-22] (Production of Blocked Polyisocyanate Composition BL-a1-22) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was mixed under a nitrogen stream with 100 parts by weight of the polyisocyanate P1-1 obtained in Synthesis Example 1-1, 5.9 parts by weight of polycaprolactone diol (C1) (Daicel Corporation, "Placcel 205UT" (trade name), number average molecular weight 530, average functionality 2), 0.008 parts by weight of 2-ethylhexyl acid phosphate (Johoku Chemical Industry Co., Ltd., "JP-508T" (trade name)), and 57.0 parts by weight of dipropylene glycol dimethyl ether (DPDM), and the mixture was reacted at 80°C for 3 hours. The reaction solution was cooled to 40°C, and diisopropyl malonate (B1) was added in an amount equimolar to the isocyanate groups. Dipropylene glycol dimethyl ether (DPDM) was then added to adjust the solids content to 60% by weight. Next, 1.1 parts by mass of a methanol solution containing sodium methylate (28% by mass relative to the total mass of the solution) was added dropwise with stirring, and the external bath was adjusted so that the solution temperature was 47°C. The blocking reaction was carried out at 47°C for at least 6 hours, yielding a blocked polyisocyanate composition intermediate. Subsequently, 200 mol% of tert-butanol, based on the blocked isocyanate groups, was added, and the reaction was carried out at 80°C for 3 hours while the generated isopropyl alcohol was removed by distillation under atmospheric pressure. The isopropanol and tert-butanol were then distilled off at 60°C under reduced pressure (50 kPa). Finally, dipropylene glycol dimethyl ether (DPDM) was added to adjust the solids content to 60% by mass, yielding blocked polyisocyanate composition BL-a1-22. The resulting blocked polyisocyanate composition BL-a1-22 had a solids content of 60.0% by mass and a weight-average molecular weight of 9.0 x 10. 3 It was.

[0304] [Example 1-24] (Production of Blocked Polyisocyanate Composition BL-a1-24) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was mixed under a nitrogen stream with 100 parts by weight of the polyisocyanate P1-1 obtained in Synthesis Example 1-1, 5.9 parts by weight of polycaprolactone diol (C1) (Daicel Corporation, "Placcel 205UT" (trade name), number average molecular weight 530, average functionality 2), 0.008 parts by weight of 2-ethylhexyl acid phosphate (Johoku Chemical Industry Co., Ltd., "JP-508T" (trade name)), and 57.0 parts by weight of dipropylene glycol dimethyl ether (DPDM), and the mixture was reacted at 80°C for 3 hours. The reaction solution was cooled to 40°C, and diisopropyl malonate (B1) was added in an amount equimolar to the isocyanate groups. Dipropylene glycol dimethyl ether (DPDM) was then added to adjust the solids content to 60% by weight. Next, 1.1 parts by mass of a methanol solution containing sodium methylate (28% by mass relative to the total mass of the solution) was added dropwise with stirring, and the external bath was adjusted so that the solution temperature was 47°C. The blocking reaction was carried out at 47°C for at least 6 hours, yielding a blocked polyisocyanate composition intermediate. Subsequently, 200 mol% of 2-methyl-2-butanol, based on the blocked isocyanate groups, was added, and the reaction was carried out at 110°C for 5 hours while the generated isopropyl alcohol was removed by distillation under atmospheric pressure. The isopropanol and 2-methyl-2-butanol were then distilled off at 60°C under reduced pressure (50 kPa). Finally, dipropylene glycol dimethyl ether (DPDM) was added to adjust the solids content to 60% by mass, yielding blocked polyisocyanate composition BL-a1-24. The resulting blocked polyisocyanate composition BL-a1-24 had a solids content of 60.0% by mass and a weight-average molecular weight of 9.0 x 10. 3 It was.

[0305] [Example 1-25] (Production of Blocked Polyisocyanate Composition BL-a1-25) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by weight of the polyisocyanate P1-1 obtained in Synthesis Example 1-1 and diisopropyl malonate (B1) in an equimolar amount relative to the socyanate groups under a nitrogen stream. Dipropylene glycol dimethyl ether (DPDM) was then added to adjust the solids content to 60% by weight. Next, 1.1 parts by weight of a methanol solution containing sodium methylate (28% by weight based on the total weight of the solution) was added dropwise with stirring. The external bath was then adjusted to a solution temperature of 47°C, and the blocking reaction was carried out at 47°C for at least 6 hours. Subsequently, 5.9 parts by weight of polycaprolactone diol (C1) (Daicel Corporation, "PLACCEL 205UT" (trade name), number average molecular weight 530, average functionality 2) was added, and the external bath was adjusted to a solution temperature of 80°C, and the reaction was carried out for 2 hours. Next, 2-methyl-2-butanol was added in an amount of 200 mol% relative to the blocked isocyanate groups, and the mixture was allowed to react at 110°C for 5 hours while the generated isopropyl alcohol was removed by distillation under normal pressure. The isopropanol and 2-methyl-2-butanol were then distilled off at 60°C under reduced pressure (50 kPa). Finally, dipropylene glycol dimethyl ether (DPDM) was added to adjust the solids content to 60% by mass, yielding blocked polyisocyanate composition BL-a1-25. The resulting blocked polyisocyanate composition BL-a1-25 had a solids content of 60.0% by mass and a weight-average molecular weight of 9.0 x 10 3 It was.

[0306] <Production of polyhydroxy compounds> [Manufacturing Example 1] (Production of polyhydroxy compound OHP1) A four-neck flask equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet was charged with 29 parts by weight of propylene glycol monomethyl ether and heated to 110°C under nitrogen gas flow. After reaching 110°C, the nitrogen gas flow was stopped, and a mixture consisting of 22.3 parts by weight of 2-hydroxyethyl methacrylate, 8.0 parts by weight of methyl methacrylate, 26.1 parts by weight of butyl acrylate, 42.3 parts by weight of styrene, 1.3 parts by weight of acrylic acid, and 1.9 parts by weight of 2,2'-azobis(isobutyronitrile) was added dropwise over 5.5 hours. The mixture was then stirred at 115°C for 3 hours under a nitrogen gas flow, cooled to 30°C, and the solvent was subsequently removed using an evaporator. Butyl acetate was then added to obtain a solution of polyhydroxy compound OHP1, an acrylic polyol-based resin with a solids content of 60% by weight. Polyhydroxy compound OHP1 had a weight-average molecular weight (Mw) of 2.73 x 10 4 The hydroxyl value was 139 mgKOH / g and the glass transition temperature Tg was 29.8°C.

[0307] In the following Tables 1 to 6, the abbreviations represent the following compounds. (Polyol A) C1: Polycaprolactone diol (manufactured by Daicel Corporation, "Placcel 205UT" (trade name), number average molecular weight 530, average number of functional groups 2) C2: Polycaprolactone diol (manufactured by Daicel Corporation, "Placcel 220CPT" (trade name), number average molecular weight 2000, average number of functional groups 2) C3: Polycaprolactone diol (manufactured by Daicel Corporation, "Placcel 240CP" (trade name), number average molecular weight 4000, average number of functional groups 2) C4: 1,4-butanediol (molecular weight 90.12, number of hydroxyl groups 2) C5: 1,3-butanediol (molecular weight 90.12, number of hydroxyl groups 2)

[0308] (blocking agent) B1: Diisopropyl malonate B2: Di-tert-butyl malonate B3: Di(2-methyl-2-butyl) malonate

[0309]

Table 1

[0310]

Table 2

[0311]

Table 3

[0312]

Table 4

[0313]

Table 5

[0314]

Table 6

[0315]

Table 7

[0316]

Table 8

[0317]

Table 9

[0318]

Table 10

[0319] [Table 11]

[0320] [Table 12]

[0321] As can be seen from the table above, the blocked polyisocyanate compositions BL-a1-1 to BL-a1-16 (Examples 1-1 to 1-16) had good storage stability when formed into resin compositions, and when formed into coating films, had excellent curability, hardness, and strength at low temperatures of around 80°C. In a comparison of blocked polyisocyanate compositions BL-a1-1 to BL-a1-4 (Examples 1-1 to 1-4) containing different amounts of polyol A, it was observed that the smaller the amount of polyol A, the better the curability, hardness, and strength of the coating film at low temperatures of around 80°C. In a comparison of blocked polyisocyanate compositions BL-a1-2, BL-a1-11, and BL-a1-12 (Examples 1-2, 1-11, and 1-12) with different molar ratios of blocking agent B1 to blocking agent B2, compositions with a B1 / B2 ratio of 70 / 30 or less tended to have better curability and hardness at low temperatures of around 80°C when formed into a coating film, while compositions with a B1 / B2 ratio of 50 / 50 tended to have particularly better strength when formed into a coating film. In a comparison of blocked polyisocyanate compositions BL-a1-11, BL-a1-13, and BL-a1-14 (Examples 1-11, 1-13, and 1-14) that used different types of polyisocyanate, it was found that the smaller the average number of isocyanate groups in the polyisocyanate, the better the hardness of the coating film when formed. Conversely, the larger the average number of isocyanate groups in the polyisocyanate, the better the curing properties at low temperatures of around 80°C. Blocked polyisocyanate compositions BL-b1-1 to BL-b1-2 (Comparative Examples 1-1 and 1-2), which were not modified with polyol A, had good storage stability when formed into resin compositions, but when formed into coating films, they were poor in curability at low temperatures of around 80°C, hardness, strength, and solvent resistance.

[0322] [Preparation of Waterborne Resin Composition] An aqueous base acrylic polyol (Nuplex Corporation, "Setaqua (registered trademark) 6515" (trade name), OH (mol %) (on solids) = 3.3, Acid value (mgKOH / g) = 9.9, solid content 45% by mass) and each blocked polyisocyanate composition were blended so that the ratio of the molar amount of isocyanate groups to the molar amount of hydroxyl groups (isocyanate groups / hydroxyl groups) was 0.80. Ion-exchanged water was further blended, and a trace amount of dimethylaminoethanol was added to adjust the pH to approximately 8.0 to 8.5 and the solid content to 45% by mass. The solution was then stirred at 1000 rpm for 15 minutes using a homodisper, and after degassing, an aqueous resin composition was obtained.

[0323] [Rating 2-1] (Low temperature curing) The obtained resin composition was applied to a polypropylene (PP) plate to a dry film thickness of 40 μm, and then heated and dried at 85°C for 30 minutes to obtain a resin film. The obtained resin film was stored at room temperature (23°C) for one week, and the gel fraction was measured. The gel fraction was calculated as a percentage (mass%) obtained by dividing the mass of the undissolved portion of the resin film when immersed in acetone at 23°C for 24 hours by the mass before immersion. The low-temperature curing property was evaluated from the obtained gel fraction according to the following evaluation criteria. A rating of C or higher was considered to have good low-temperature curing property.

[0324] (Evaluation criteria) A: Initial gel fraction 85% by mass or more B: Initial gel fraction 82% by mass or more and less than 85% by mass C: Initial gel fraction 78% by mass or more and less than 82% by mass D: Initial gel fraction 70% by mass or more and less than 78% by mass E: Initial gel fraction less than 70% by mass

[0325] [Rating 2-2] (Storage stability) 20 g of the obtained aqueous polymer composition was stored at 40°C for 3 days, and then the gel fraction before storage (initial gel fraction) and after storage were measured using the aqueous polymer composition after storage. The gel fraction was determined using the method described in "Evaluation 2-1". The gel fraction retention was calculated using the following formula. Gel fraction retention (%) = (gel fraction after storage) / (initial gel fraction) × 100

[0326] The storage stability was evaluated from the obtained gel fraction retention rate according to the following evaluation criteria: A sample with an evaluation result of D or higher was evaluated as having good storage stability.

[0327] (Evaluation criteria) A: Gel fraction retention rate of 90% or more B: Gel fraction retention rate 80% or more but less than 90% C: Gel fraction retention rate 73% or more and less than 80% D: Gel fraction retention rate 67% or more and less than 73% E: Gel fraction retention rate 60% or more but less than 67% F: Gel fraction retention rate 60% or more

[0328] [Rating 2-3] (Konig hardness) A resin film was obtained on a glass plate using the same method as in "Evaluation 2-1" above. The obtained resin film was measured for Konig hardness (times) in a 23°C environment using a Konig hardness tester (Pendulum hardness tester from BYK Gardner). The Konig hardness was evaluated from the Konig hardness value according to the following evaluation criteria. A sample with an evaluation result of B or higher was evaluated as having good Konig hardness.

[0329] (Evaluation criteria) A: More than 30 times B: 25 times or more and 29 times or less C: More than 20 times and less than 24 times D: 19 times or less

[0330] [Rating 2-4] (Solvent resistance (ethanol rubbing test)) The obtained aqueous resin composition was applied to a glass plate to a dry film thickness of 40 μm, and then heated and dried at 85°C for 30 minutes to obtain a resin film. The obtained resin film was stored at room temperature (23°C) for 1 day, and then rubbed 20 times with a cotton swab soaked in ethanol at 23°C over a length of 3 cm to observe the state of the resin film. The solvent resistance was evaluated based on the state of the resin film according to the following evaluation criteria. A rating of B or higher was considered to be good solvent resistance.

[0331] (Evaluation criteria) A: Almost no deterioration is observed B: Streaks were observed in some rubbed areas. C: Streaks were observed in the rubbed area, and thinning was observed. D: There were areas where the resin film on the rubbed area was completely dissolved.

[0332] <Synthesis of Polyisocyanate> [Synthesis Example 2-1] (Synthesis of Polyisocyanate P2-1) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by mass of HDI and 5.2 parts by mass of a polyester polyol derived from a trihydric alcohol and ε-caprolactone (Daicel Chemical Industries, Ltd., "PLACCEL 303" (trade name), average functionality: 3, number-average molecular weight: 300) under a nitrogen stream. The temperature inside the reactor was maintained at 88°C for 1 hour with stirring to carry out a urethanization reaction. The temperature inside the reactor was then maintained at 62°C, and an isocyanuration catalyst, tetramethylammonium caprylate, was added. When the yield reached 51% by mass, phosphoric acid was added to terminate the reaction. The reaction solution was filtered, and unreacted HDI was removed using a thin-film evaporator to obtain an isocyanurate-type polyisocyanate (hereinafter sometimes referred to as "polyisocyanate P2-1"). The NCO content of the obtained polyisocyanate P2-1 was 18.8% by mass, the number average molecular weight was 1180, and the average number of isocyanate groups was 5.3. 1 H-NMR analysis confirmed the presence of isocyanurate groups.

[0333] [Synthesis Example 2-2] (Synthesis of polyisocyanate P2-2) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by mass of HDI under a nitrogen stream, and the temperature inside the reactor was maintained at 60°C. The isocyanuration catalyst tetramethylammonium caprylate was added, and when the yield reached 38% by mass, phosphoric acid was added to terminate the reaction. The reaction solution was filtered, and unreacted HDI was removed using a thin-film evaporator to obtain an isocyanurate-type polyisocyanate (hereinafter sometimes referred to as "polyisocyanate P2-2"). The NCO content of the obtained polyisocyanate P2-2 was 22.2% by mass, the number-average molecular weight was 650, and the average number of isocyanate groups was 3.4. Regarding the obtained polyisocyanate P2-2, 1 H-NMR analysis confirmed the presence of isocyanurate groups.

[0334] [Synthesis Example 2-3] (Synthesis of polyisocyanate P2-3) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by weight of polyisocyanate P2-1, 13 parts by weight of dipropylene glycol dimethyl ether (DPDM), 15 parts by weight of methoxypolyethylene glycol (MPG-081, 15 ethylene oxide repeating units, manufactured by Nippon Nyukazai Co., Ltd.) (5 mol % relative to 100 mol % of the isocyanate groups in polyisocyanate P2-1), 0.08 parts by weight of 2-ethylhexyl acid phosphate (JP-508T, manufactured by Johoku Chemical Industry Co., Ltd.), and dipropylene glycol dimethyl ether (DPDM) under a nitrogen stream. The resulting mixture was stirred at 120°C for 2 hours to yield polyisocyanate P2-3. The resulting polyisocyanate P2-3 had an NCO content of 14.0% by weight and an average number of isocyanate groups of 5.0.

[0335] [Synthesis Example 2-4] (Synthesis of polyisocyanate P2-4) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by weight of polyisocyanate P2-2, 13 parts by weight of dipropylene glycol dimethyl ether (DPDM), 18 parts by weight of methoxypolyethylene glycol (MPG-081, 15 ethylene oxide repeating units, manufactured by Nippon Nyukazai Co., Ltd.) (5 mol% relative to 100 mol% of the isocyanate groups in polyisocyanate P2-2), 0.08 parts by weight of 2-ethylhexyl acid phosphate (JP-508T, manufactured by Johoku Chemical Industry Co., Ltd.), and dipropylene glycol dimethyl ether (DPDM) under a nitrogen stream. The resulting mixture was stirred at 120°C for 2 hours to produce polyisocyanate P2-4. The NCO content of the resulting polyisocyanate P2-4 was 16.2% by weight, and the average number of isocyanate groups was 3.2.

[0336] <Production of Blocked Polyisocyanate Composition> [Example 2-1] (Production of Blocked Polyisocyanate Composition BL-a2-1) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by weight of the polyisocyanate P2-3 obtained in Synthesis Example 2-3, 43.9 parts by weight of diisopropyl malonate (70 mol % relative to 100 mol % of NCO groups), and 23.0 parts by weight of (2-methyl-2-pentyl)isopropyl malonate (30 mol % relative to 100 mol % of NCO groups) under a nitrogen stream. Dipropylene glycol dimethyl ether (DPDM) was then added dropwise to the mixture to adjust the solids content to 60% by weight. Subsequently, 1.0 part by weight of a methanol solution containing sodium methylate (28% by weight relative to the total weight of the solution) was added dropwise with stirring. The external bath was then adjusted to a solution temperature of 55°C, and the blocking reaction was carried out at 55°C for 5 hours to obtain blocked polyisocyanate composition BL-a2-1 with a solids content of 60% by weight.

[0337] [Example 2-2] (Production of Blocked Polyisocyanate Composition BL-a2-2) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by weight of the polyisocyanate P2-3 obtained in Synthesis Example 2-3, 43.9 parts by weight of diisopropyl malonate (70 mol % relative to 100 mol % of NCO groups), and 21.6 parts by weight of (2-methyl-2-butyl)isopropyl malonate (30 mol % relative to 100 mol % of NCO groups) under a nitrogen stream. Dipropylene glycol dimethyl ether (DPDM) was then added dropwise to the mixture to adjust the solids content to 60% by weight. Subsequently, 1.0 part by weight of a methanol solution containing sodium methylate (28% by weight relative to the total weight of the solution) was added dropwise with stirring. The external bath was then adjusted to a solution temperature of 55°C, and the blocking reaction was carried out at 55°C for 5 hours to obtain blocked polyisocyanate composition BL-a2-2 with a solids content of 60% by weight.

[0338] [Example 2-3] (Production of Blocked Polyisocyanate Composition BL-a2-3) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by weight of the polyisocyanate P2-3 obtained in Synthesis Example 2-3 and 63.9 parts by weight of diisopropyl malonate (102 mol% relative to 100 mol% NCO groups) under a nitrogen stream. Dipropylene glycol dimethyl ether (DPDM) was then added to adjust the solids content to 60% by weight. Next, with stirring, 1.0 part by weight of a methanol solution containing sodium methylate (28% by weight relative to the total weight of the solution) was added dropwise, and the external bath was adjusted to a solution temperature of 55°C. The blocking reaction was carried out at 55°C for 5 hours to obtain a blocked polyisocyanate composition intermediate with a solids content of 60% by weight. Subsequently, 30 parts by weight of 2-methyl-2-butanol (100 mol% relative to blocked isocyanate groups) was added, and the reaction was carried out at 80°C for 3 hours while the generated isopropyl alcohol was removed by distillation under atmospheric pressure. Thereafter, isopropanol and 2-methyl-2-butanol were further distilled off at 60°C under reduced pressure (50 kPa), and finally, dipropylene glycol dimethyl ether (DPDM) was added to adjust the solid content to 60 mass%, thereby obtaining blocked polyisocyanate composition BL-a2-3.

[0339] [Example 2-4] (Production of Blocked Polyisocyanate Composition BL-a2-4) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by weight of the polyisocyanate P2-3 obtained in Synthesis Example 2-3 and 63.9 parts by weight of diisopropyl malonate (102 mol % relative to 100 mol % NCO groups) under a nitrogen stream. Dipropylene glycol dimethyl ether (DPDM) was then added to adjust the solids content to 60% by weight. Next, with stirring, 1.0 part by weight of a methanol solution containing sodium methylate (28% by weight relative to the total weight of the solution) was added dropwise, and the external bath was adjusted to raise the solution temperature to 55°C. The blocking reaction was carried out at 55°C for 5 hours to obtain a blocked polyisocyanate composition intermediate with a solids content of 60% by weight. Subsequently, 15 parts by weight of 2-methyl-2-butanol (50 mol % relative to blocked isocyanate groups) was added, and the reaction was carried out at 80°C for 3 hours while the generated isopropyl alcohol was removed by distillation under atmospheric pressure. Thereafter, isopropanol and 2-methyl-2-butanol were further distilled off at 60°C under reduced pressure (50 kPa), and finally, dipropylene glycol dimethyl ether (DPDM) was added to adjust the solid content to 60 mass%, thereby obtaining blocked polyisocyanate composition BL-a2-4.

[0340] [Example 2-5] (Production of Blocked Polyisocyanate Composition BL-a2-5) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by weight of the polyisocyanate P2-3 obtained in Synthesis Example 2-3, 31.3 parts by weight (50 mol % relative to 100 mol % NCO groups), and 34.0 parts by weight (50 mol % relative to 100 mol % NCO groups) of 2-methyl-2-butylisopropyl malonate under nitrogen flow. Dipropylene glycol dimethyl ether (DPDM) was then added dropwise to the mixture to a solids content of 60% by weight. Subsequently, 1.0 part by weight of a methanol solution containing sodium methylate (28% by weight relative to the total weight of the solution) was added dropwise with stirring. The external bath was then adjusted to a solution temperature of 55°C, and the blocking reaction was carried out at 55°C for 5 hours to obtain blocked polyisocyanate composition BL-a2-5 with a solids content of 60% by weight.

[0341] [Example 2-6] (Production of Blocked Polyisocyanate Composition BL-a2-6) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by weight of the polyisocyanate P2-3 obtained in Synthesis Example 2-3, 60.2 parts by weight of diisopropyl malonate (96 mol % relative to 100 mol % of NCO groups), and 2.9 parts by weight of (2-methyl-2-butyl)isopropyl malonate (4 mol % relative to 100 mol % of NCO groups) under a nitrogen stream. Dipropylene glycol dimethyl ether (DPDM) was then added dropwise to the mixture to adjust the solids content to 60% by weight. Subsequently, 1.0 part by weight of a methanol solution containing sodium methylate (28% by weight relative to the total weight of the solution) was added dropwise with stirring. The external bath was then adjusted to a solution temperature of 55°C, and the blocking reaction was carried out at 55°C for 5 hours to obtain blocked polyisocyanate composition BL-a2-6 with a solids content of 60% by weight.

[0342] [Example 2-7] (Production of Blocked Polyisocyanate Composition BL-a2-7) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by weight of the polyisocyanate P2-3 obtained in Synthesis Example 2-3 and 54.4 parts by weight of diethyl malonate (102 mol % relative to 100 mol % NCO groups) under a nitrogen stream. Dipropylene glycol dimethyl ether (DPDM) was then added to adjust the solids content to 60% by weight. Next, with stirring, 1.0 part by weight of a methanol solution containing sodium methylate (28% by weight relative to the total weight of the solution) was added dropwise, and the external bath was adjusted to raise the solution temperature to 55°C. The blocking reaction was carried out at 55°C for 5 hours to obtain a blocked polyisocyanate composition intermediate with a solids content of 60% by weight. Subsequently, 30 parts by weight of 2-methyl-2-butanol (100 mol % relative to blocked isocyanate groups) was added, and the reaction was carried out at 80°C for 5 hours while the generated ethanol was removed by distillation under atmospheric pressure. Then, ethanol and 2-methyl-2-butanol were further distilled off at 60°C under reduced pressure (50 kPa), and finally, dipropylene glycol dimethyl ether (DPDM) was added to adjust the solid content to 60 mass%, thereby obtaining blocked polyisocyanate composition BL-a2-7.

[0343] [Example 2-8] (Production of Blocked Polyisocyanate Composition BL-a2-8) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by weight of the polyisocyanate P2-3 obtained in Synthesis Example 2-3 and 63.9 parts by weight of diisopropyl malonate (102 mol % relative to 100 mol % NCO groups) under a nitrogen stream. Dipropylene glycol dimethyl ether (DPDM) was then added to adjust the solids content to 60% by weight. Next, with stirring, 1.0 part by weight of a methanol solution containing sodium methylate (28% by weight relative to the total weight of the solution) was added dropwise, and the external bath was adjusted to a solution temperature of 55°C. The blocking reaction was carried out at 55°C for 5 hours to obtain a blocked polyisocyanate composition intermediate with a solids content of 60% by weight. Subsequently, 34.8 parts by weight of 3-methyl-3-pentanol (100 mol % relative to blocked isocyanate groups) was added, and the reaction was carried out at 80°C for 3 hours while the generated isopropyl alcohol was removed by distillation under atmospheric pressure. Thereafter, isopropanol and 3-methyl-3-pentanol were further distilled off at 60°C under reduced pressure (50 kPa), and finally, dipropylene glycol dimethyl ether (DPDM) was added to adjust the solid content to 60 mass%, thereby obtaining blocked polyisocyanate composition BL-a2-8.

[0344] [Example 2-9] (Production of Blocked Polyisocyanate Composition BL-a2-9) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by weight of the polyisocyanate P2-4 obtained in Synthesis Example 2-4 and 73.9 parts by weight of diisopropyl malonate (102 mol % relative to 100 mol % NCO groups) under a nitrogen stream. Dipropylene glycol dimethyl ether (DPDM) was then added to adjust the solids content to 60% by weight. Next, with stirring, 1.0 part by weight of a methanol solution containing sodium methylate (28% by weight relative to the total weight of the solution) was added dropwise, and the external bath was adjusted to raise the solution temperature to 55°C. The blocking reaction was carried out at 55°C for 5 hours to obtain a blocked polyisocyanate composition intermediate with a solids content of 60% by weight. Next, 40.2 parts by weight of 3-methyl-3-pentanol (100 mol % relative to blocked isocyanate groups) was added, and the reaction was carried out at 80°C for 3 hours while the generated isopropyl alcohol was removed by distillation under atmospheric pressure. Thereafter, isopropanol and 3-methyl-3-pentanol were further distilled off at 60°C under reduced pressure (50 kPa), and finally, dipropylene glycol dimethyl ether (DPDM) was added to adjust the solid content to 60 mass%, thereby obtaining blocked polyisocyanate composition BL-a2-9.

[0345] [Example 2-10] (Production of Blocked Polyisocyanate Composition BL-a2-10) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by weight of the polyisocyanate P2-3 obtained in Synthesis Example 2-3 and 63.9 parts by weight of diisopropyl malonate (102 mol % relative to 100 mol % NCO groups) under a nitrogen stream. Dipropylene glycol dimethyl ether (DPDM) was then added to adjust the solids content to 60% by weight. Next, with stirring, 1.0 part by weight of a methanol solution containing sodium methylate (28% by weight relative to the total weight of the solution) was added dropwise, and the external bath was adjusted to a solution temperature of 55°C. The blocking reaction was carried out at 55°C for 5 hours to obtain a blocked polyisocyanate composition intermediate with a solids content of 60% by weight. Next, 43.3 parts by weight of 3-ethyl-3-hexanol (100 mol % relative to blocked isocyanate groups) was added, and the reaction was carried out at 80°C for 3 hours while the generated isopropyl alcohol was removed by distillation under atmospheric pressure. Thereafter, isopropanol and 3-ethyl-3-hexanol were further distilled off at 60°C under reduced pressure (30 kPa), and finally, dipropylene glycol dimethyl ether (DPDM) was added to adjust the solid content to 60 mass%, thereby obtaining blocked polyisocyanate composition BL-a2-10.

[0346] [Example 2-11] (Production of Blocked Polyisocyanate Composition BL-a2-11) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by weight of the polyisocyanate P2-3 obtained in Synthesis Example 2-3, 12.5 parts by weight of diisopropyl malonate (20 mol % relative to 100 mol % of NCO groups), and 57.5 parts by weight of (2-methyl-2-butyl)isopropyl malonate (80 mol % relative to 100 mol % of NCO groups) under a nitrogen stream. Dipropylene glycol dimethyl ether (DPDM) was then added dropwise to the mixture to adjust the solids content to 60% by weight. Subsequently, 1.0 part by weight of a methanol solution containing sodium methylate (28% by weight relative to the total weight of the solution) was added dropwise with stirring. The external bath was then adjusted to a solution temperature of 55°C, and the blocking reaction was carried out at 55°C for 5 hours to obtain blocked polyisocyanate composition BL-a2-11 with a solids content of 60% by weight.

[0347] [Example 2-12] (Production of Blocked Polyisocyanate Composition BL-a2-12) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by weight of the polyisocyanate P2-3 obtained in Synthesis Example 2-3 and 63.9 parts by weight of diisopropyl malonate (102 mol% relative to 100 mol% NCO groups) under a nitrogen stream. Dipropylene glycol dimethyl ether (DPDM) was then added to adjust the solids content to 60% by weight. Next, with stirring, 1.0 part by weight of a methanol solution containing sodium methylate (28% by weight relative to the total weight of the solution) was added dropwise, and the external bath was adjusted to raise the solution temperature to 55°C. The blocking reaction was carried out at 55°C for 5 hours to obtain a blocked polyisocyanate composition intermediate with a solids content of 60% by weight. Subsequently, 75 parts by weight of 2-methyl-2-butanol (250 mol% relative to blocked isocyanate groups) was added, and the reaction was carried out at 80°C for 3 hours while the generated isopropyl alcohol was removed by distillation under atmospheric pressure. Thereafter, isopropanol and 2-methyl-2-butanol were further distilled off at 60°C under reduced pressure (50 kPa), and finally, dipropylene glycol dimethyl ether (DPDM) was added to adjust the solid content to 60 mass%, thereby obtaining blocked polyisocyanate composition BL-a2-12.

[0348] [Example 2-13] (Production of Blocked Polyisocyanate Composition BL-a2-13) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by weight of the polyisocyanate P2-3 obtained in Synthesis Example 2-3, 43.9 parts by weight of diisopropyl malonate (70 mol% relative to 100 mol% NCO groups), and 24.4 parts by weight of di(2-methyl-2-butyl) malonate (30 mol% relative to 100 mol% NCO groups) under a nitrogen stream. Dipropylene glycol dimethyl ether (DPDM) was then added dropwise to the mixture to a solids content of 60% by weight. Subsequently, 1.0 part by weight of a methanol solution containing sodium methylate (28% by weight relative to the total weight of the solution) was added dropwise with stirring. The external bath was then adjusted to a solution temperature of 55°C, and the blocking reaction was carried out at 55°C for 5 hours to obtain blocked polyisocyanate composition BL-a2-13 with a solids content of 60% by weight.

[0349] [Comparative Example 2-1] (Production of Blocked Polyisocyanate Composition BL-b2-1) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by weight of the polyisocyanate P2-3 obtained in Synthesis Example 2-3, 43.9 parts by weight of diisopropyl malonate (70 mol% relative to 100 mol% of NCO groups), and 50.5 parts by weight of di-tert-butyl malonate (30 mol% relative to 100 mol% of NCO groups) under a nitrogen stream. Dipropylene glycol dimethyl ether (DPDM) was then added dropwise to the mixture to a solids content of 60% by weight. Subsequently, 1.0 part by weight of a methanol solution containing sodium methylate (28% by weight relative to the total weight of the solution) was added dropwise with stirring. The external bath was then adjusted to a solution temperature of 55°C, and the blocking reaction was carried out at 55°C for 5 hours to obtain blocked polyisocyanate composition BL-b2-1 with a solids content of 60% by weight.

[0350] [Comparative Example 2-2] (Production of Blocked Polyisocyanate Composition BL-b2-2) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by weight of the polyisocyanate P2-3 obtained in Synthesis Example 2-3 and 63.9 parts by weight of diisopropyl malonate (102 mol% relative to 100 mol% NCO groups) under a nitrogen stream. Dipropylene glycol dimethyl ether (DPDM) was then added to adjust the solids content to 60% by weight. Next, with stirring, 1.0 part by weight of a methanol solution containing sodium methylate (28% by weight relative to the total weight of the solution) was added dropwise. The external bath was then adjusted to a solution temperature of 55°C, and the blocking reaction was carried out at 55°C for 5 hours to obtain blocked polyisocyanate composition BL-b2-2 with a solids content of 60% by weight.

[0351] [Comparative Example 2-3] (Production of Blocked Polyisocyanate Composition BL-b2-3) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by weight of the polyisocyanate P2-3 obtained in Synthesis Example 2-3 and 54.3 parts by weight of diethyl malonate (102 mol% relative to 100 mol% NCO groups) under a nitrogen stream. Dipropylene glycol dimethyl ether (DPDM) was then added to adjust the solids content to 60% by weight. Next, with stirring, 1.0 part by weight of a methanol solution containing sodium methylate (28% by weight relative to the total weight of the solution) was added dropwise. The external bath was then adjusted to a solution temperature of 55°C, and the blocking reaction was carried out at 55°C for 5 hours to obtain blocked polyisocyanate composition BL-b2-3 with a solids content of 60% by weight.

[0352] [Comparative Example 2-4] (Production of Blocked Polyisocyanate Composition BL-b2-4) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by weight of the polyisocyanate P2-3 obtained in Synthesis Example 2-3 and 63.9 parts by weight of diisopropyl malonate (102 mol % relative to 100 mol % NCO groups) under a nitrogen stream. Dipropylene glycol dimethyl ether (DPDM) was then added to adjust the solids content to 60% by weight. Next, 1.0 part by weight of a methanol solution containing sodium methylate (28% by weight relative to the total weight of the solution) was added dropwise with stirring. The external bath was then adjusted to a solution temperature of 55°C. The blocking reaction was carried out at 55°C for 5 hours, yielding a blocked polyisocyanate composition intermediate with a solids content of 60% by weight. Subsequently, 49.3 parts by weight of tert-butanol (150 mol % relative to blocked isocyanate groups) was added, and the reaction was carried out under reflux at 80°C for 5 hours. Thereafter, isopropanol and tert-butanol were further distilled off at 60°C under reduced pressure (50 kPa), and finally, dipropylene glycol dimethyl ether (DPDM) was added to adjust the solid content to 60 mass % to obtain blocked polyisocyanate composition BL-b2-4.

[0353] [Comparative Example 2-5] (Production of Blocked Polyisocyanate Composition BL-b2-5) A four-neck flask equipped with a thermometer, stirring blade, and reflux condenser was charged with 100 parts by weight of the polyisocyanate P2-3 obtained in Synthesis Example 2-3 and 73.4 parts by weight of di-tert-butyl malonate (102 mol% relative to 100 mol% NCO groups) under a nitrogen stream. Dipropylene glycol dimethyl ether (DPDM) was then added to adjust the solids content to 60% by weight. Next, 1.0 part by weight of a methanol solution containing sodium methylate (28% by weight relative to the total weight of the solution) was added dropwise with stirring. The external bath was then adjusted to a solution temperature of 55°C, and the blocking reaction was carried out at 55°C for 5 hours to obtain blocked polyisocyanate composition BL-b2-5 with a solids content of 60% by weight.

[0354] The results of measuring the physical properties of the blocked polyisocyanate compositions obtained in the examples and comparative examples and the results of evaluation by the methods described above are shown in the table below.

[0355] [Table 13]

[0356] [Table 14]

[0357] [Table 15]

[0358] [Table 16]

[0359] [Table 17]

[0360] [Table 18]

[0361] [Table 19]

[0362] [Table 20]

[0363] From Tables 13 to 20, R in the structural unit (I) 11 , R 12 and R 13Block polyisocyanate compositions BL-a2-1 to BL-a2-10 (Examples 2-1 to 2-10) having a total carbon number of 4 or more had particularly good storage stability when made into a resin composition, and good solvent resistance when made into a resin film. Furthermore, in blocked polyisocyanate compositions BL-a2-2 to BL-a2-6 (Examples 2-2 to 2-6) with different molar ratios of structural unit (II) / structural unit (I), the smaller the molar ratio of structural unit (II) / structural unit (I), the better the low-temperature curing properties and Konig hardness of the resin film formed.On the other hand, the larger the molar ratio of structural unit (II) / structural unit (I), the better the storage stability. R in structural unit (I) 11 , R 12 and R 13 In the blocked polyisocyanate compositions BL-a2-3 and BL-a2-10 (Examples 2-3 and 2-10) with different alkyl groups, R 11 , R 12 and R 13 Block polyisocyanate composition BL-a2-3, which has a total of 4 carbon atoms, tended to have better low-temperature curing properties, Konig hardness, and solvent resistance when made into a resin film. Furthermore, in blocked polyisocyanate compositions BL-a2-3 and BL-a2-7 (Examples 2-3 and 2-7), which differ in the type of blocking agent from which the structural unit (II) is derived, BL-a2-3, which used diisopropyl malonate, tended to have better low-temperature curing properties and Konig hardness when formed into a resin film than BL-a2-7, which used diethyl malonate. Furthermore, among blocked polyisocyanate compositions BL-a2-8 and BL-a2-9 (Examples 2-8 and 2-9) in which different types of polyisocyanate were used in the blocking reaction, blocked polyisocyanate composition BL-a2-8, which used a polyisocyanate with a larger average number of isocyanate groups, tended to have better low-temperature curing properties and Konig hardness when formed into a resin film.

[0364] On the other hand, R in the structural unit (I)11 , R 12 and R 13 In the blocked polyisocyanate compositions BL-b2-1 (Comparative Example 2-1), BL-b2-4 (Comparative Example 2-4), and BL-b2-5 (Comparative Example 2-5), in which the total number of carbon atoms is 3, the low-temperature curing properties, Konig hardness, and solvent resistance were maintained favorably when formed into a resin film, but the storage stability was poor when formed into an aqueous resin composition. Furthermore, in the blocked polyisocyanate composition BL-b2-2 (Comparative Example 2-2) and the blocked polyisocyanate BL-b2-3 (Comparative Example 2-3), which did not contain the structural unit (I), good storage stability was maintained when they were made into aqueous resin compositions, but when they were made into resin films, the low-temperature curing properties, Konig hardness, and solvent resistance were poor. [Industrial Applicability]

[0365] The blocked polyisocyanate composition of the present embodiment can provide a blocked polyisocyanate composition that has good storage stability when made into a resin composition, and that has excellent curability, hardness, and strength at a low temperature of about 80°C when made into a coating film.

Claims

1. A blocked polyisocyanate derived from a polyisocyanate and one or more blocking agents, The blocked polyisocyanate contains a structural unit represented by general formula (I) and a structural unit represented by general formula (II), The structural unit represented by the general formula (I) may be any of the following R １６ represents a hydrogen atom; A blocked polyisocyanate in which the molar ratio of the structural unit represented by the general formula (II) to the structural unit represented by the general formula (I) is 4 / 96 or more and 96 / 4 or less. 【Chemical 1】 In the general formula (I), R １１ , R １２ and R １３ are each independently an alkyl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group, and R １１ , R １２ and R １３ The total number of carbon atoms in R is 4 or more and 20 or less. １４ , R １５ and R １６ are each independently a hydrogen atom or an alkyl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group. A wavy line represents a bond. 【Chemistry 2】 In the general formula (II), R ２１ , R ２２ , R ２３ and R ２４ are each independently a hydrogen atom or an alkyl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group. A wavy line represents a bond.

2. In the general formula (I), R １１ , R １２ and R １３ The blocked polyisocyanate according to claim 1 , wherein each independently represents a methyl group or an ethyl group.

3. 3. The blocked polyisocyanate according to claim 1, wherein a portion of the isocyanate groups of the polyisocyanate is modified with a nonionic compound.

4. The blocked polyisocyanate according to any one of claims 1 to 3, wherein the average number of isocyanate groups in the polyisocyanate is 2 or more.

5. The blocked polyisocyanate according to any one of claims 1 to 4, wherein the polyisocyanate is a polyisocyanate derived from one or more diisocyanates selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates.

6. The blocked polyisocyanate according to any one of claims 1 to 5, wherein the blocked polyisocyanate has an isocyanurate group.

7. A blocked polyisocyanate composition comprising the blocked polyisocyanate according to any one of claims 1 to 6 and a solvent.

8. A resin composition comprising the blocked polyisocyanate according to any one of claims 1 to 6 or the blocked polyisocyanate composition according to claim 7, and a polyvalent hydroxy compound.

9. A resin film obtained by curing the resin composition according to claim 8.

10. A laminate comprising two or more layers of the resin film according to claim 9, each layer having a different composition, The laminate has a thickness of 1 μm or more and 50 μm or less per layer.

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