Substrate coating composition, multilayer coating laminate and method for forming multilayer coating laminate

Abstract

A substrate coating composition, a multilayer coating laminate, and a method for forming the multilayer coating laminate are provided. [Problem] To provide a substrate coating composition that can produce a multilayer coating laminate with excellent hardness and water resistance even when cured at low temperatures. [Solution] A substrate coating composition for forming a multilayer coating laminate on a substrate, the multilayer coating laminate having a substrate layer and one or more coating layers, the substrate coating composition comprising a polyisocyanate component (A) and a hydroxyl-containing resin component, the polyisocyanate component (A) comprising a polyisocyanate containing a sulfonate anion group in its molecule and a tertiary ammonium cation of one or more amine compounds represented by general formula (1).

Description

Technical Field

[0001] This invention relates to a coating composition for a substrate, a multilayer coating laminate, and a method for forming a multilayer coating laminate. Background Technology

[0002] In recent years, the application of water-based coating compositions has been increasing, for example, as primers for automotive exterior and interior trim panels. These water-based coating compositions contain virtually no organic solvents, making them preferable from the viewpoint of preventing environmental pollution.

[0003] For example, Patent Document 1 discloses a waterborne coating composition that combines a water-based polyol and a specific melamine.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 7-207220 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] On the other hand, there is a great need for coating compositions that can be used with plastics with low heat resistance, in addition to protecting the Earth's environment. Coating compositions that can be used with plastics with low heat resistance refer to coating compositions that exhibit film-forming properties even at low curing temperatures.

[0009] However, the technology disclosed in Patent Document 1 has the problem that when the curing temperature is low, the chipping resistance and coating hardness of the multilayer coating laminate become insufficient.

[0010] The present invention was made in view of the above circumstances, and its object is to provide a substrate coating composition that can produce a multilayer coating laminate with excellent hardness and water resistance even when cured at low temperature, a multilayer coating laminate using the above-mentioned substrate coating composition, and a method for forming the above-mentioned multilayer coating laminate.

[0011] In this instruction manual, "curing at low temperature" means a curing temperature range of 40°C or higher and 140°C or lower.

[0012] Solution for solving the problem

[0013] That is, the present invention includes the following methods.

[0014] [1] A base coating composition for forming a multilayer coating laminate on a substrate, the multilayer coating laminate having a base layer and one or more coating layers, the base coating composition comprising a polyisocyanate component (A) and a hydroxyl-containing resin component, the polyisocyanate component (A) comprising a polyisocyanate containing a sulfonate anion group in the molecule and a tertiary ammonium cation of one or more amine compounds represented by the following general formula (1).

[0015]

[0016] (In general formula (1), R) 11 R 12 and R 13 Independently, each group consists of a hydrocarbon group containing an ether bond and having 1 or more but fewer than 10 carbon atoms. The group is selected from R. 11 R 12 and R 13 At least one of the groups may optionally contain a ring structure, chosen freely from R. 11 R 12 and R 13 Two or more of the constituent elements can be optionally bonded together to form a ring structure. The aforementioned ring structure can be an aromatic ring, a cycloalkyl group with 5 or 6 carbon atoms, or an R-shaped ring. 11 With R 12 5-membered rings or 6-membered rings, or R-shaped rings formed by mutual bonding 11 With R 12 With R 13 (Multi-ringed structures formed by mutual bonding.)

[0017] [2] According to the coating composition for substrates described in [1], wherein the polyisocyanate component (A) comprises a urea diketone dimer of a diisocyanate monomer and an isocyanurate trimer of a diisocyanate monomer.

[0018] [3] According to the coating composition for substrates described in [2], the content of the above-mentioned diuretic dimer is 1.0% by mass or more and 20.0% by mass or less relative to the total mass of the above-mentioned polyisocyanate component (A).

[0019] [4] The base coating composition according to any one of [1] to [3], wherein the above-mentioned polyisocyanate component (A) contains an iminooxadiazine dione group and the specific molar ratio shown in the following formula (2) is 0.05 or more and 0.60 or less.

[0020] Specific molar ratio = (B+C) / (A+B+C)(2)

[0021] (In formula (2), A represents the content ratio (mol%) of the isocyanurate group shown in formula (I), B represents the content ratio (mol%) of the iminooxadiazine dione group shown in formula (II), and C represents the content ratio (mol%) of the urea dione group shown in formula (III).)

[0022]

[0023] [5] According to the coating composition for substrates described in [4], wherein the polyisocyanate containing sulfonate anionic groups in the molecule is a reaction product of an amine salt of a sulfonic acid with active hydrogen groups and a polyisocyanate, and the amine salt of the sulfonic acid with active hydrogen groups is a salt of a sulfonic acid with active hydrogen groups and an amine compound represented by the above general formula (1).

[0024] [6] The base coating composition according to any one of [1] to [5], wherein the above-mentioned polyisocyanate component (A) is an aliphatic polyisocyanate.

[0025] [7] A multilayer coating laminate, which is a multilayer coating laminate formed by sequentially stacking a first coating, a second coating and a third coating, wherein the first coating is formed by a substrate coating composition as described in any one of [1] to [6], the second coating is formed by a coating composition containing a hydroxyl resin component, and the third coating is formed by a two-component coating composition containing a hydroxyl resin component and a polyisocyanate component.

[0026] [8] According to the multilayer coating laminate of [7], wherein the second coating is formed of a hydroxyl-containing resin component and a capped polyisocyanate component (D).

[0027] [9] According to the multilayer coating laminate of [8], wherein the above-mentioned end-capped polyisocyanate component (D) comprises the structural unit (I) shown in the following general formula (I).

[0028]

[0029] (In general formula (I), R) 11 R 12 and R 13 Each is independently an alkyl group that optionally contains one or more substituents selected from the group consisting of hydroxyl and amino groups, R 11 R 12 and R 13 The total carbon number is 4 or more and less than 20, R 14 R 15 and R 16Each is an alkyl group that is independently composed of a hydrogen atom or optionally contains one or more substituents selected from the group consisting of hydroxyl and amino groups. The wavy line indicates the bonding site with the residue formed by removing the isocyanate group from the polyisocyanate.

[0030]

[10] A method for forming a multilayer coating laminate includes the following steps: applying a first coating composition to a substrate to obtain a first uncured coating; applying a second coating composition to the first uncured coating to obtain a second uncured coating; applying a third coating composition to the second uncured coating to obtain a third uncured coating; and simultaneously curing the first uncured coating, the second uncured coating, and the third uncured coating by heating at a temperature of 40°C or higher and 140°C or lower to form a multilayer coating laminate comprising the first coating, the second coating, and the third coating, wherein the first coating composition is a substrate coating composition as described in [1] or [2], the second coating composition is a coating composition comprising a hydroxyl-containing resin component, and the third coating composition is a two-component coating composition comprising a hydroxyl-containing resin component and a polyisocyanate component.

[0031]

[11] According to the method for forming a multilayer coating laminate as described in

[10] , the second coating composition is a coating composition comprising a hydroxyl-containing resin component and a capped polyisocyanate component (D).

[0032]

[12] According to the method for forming a multilayer coating laminate as described in

[11] , wherein the end-capped polyisocyanate contained in the above-mentioned end-capped polyisocyanate component (D) comprises a structural unit (I) represented by the following general formula (I).

[0033]

[0034] (In general formula (I), R) 11 R 12 and R 13 Each is independently an alkyl group that optionally contains one or more substituents selected from the group consisting of hydroxyl and amino groups, R 11 R 12 and R 13 The total carbon number is 4 or more and less than 20, R 14 R 15 and R 16 Each is an alkyl group that is independently composed of a hydrogen atom or optionally contains one or more substituents selected from the group consisting of hydroxyl and amino groups. The wavy line indicates the bonding site with the residue formed by removing the isocyanate group from the polyisocyanate.

[0035] The effects of the invention

[0036] According to the present invention, a substrate coating composition capable of producing a multilayer coating laminate with excellent hardness and water resistance even when cured at low temperatures can be provided, a multilayer coating laminate using the above-mentioned substrate coating composition, and a method for forming the above-mentioned multilayer coating laminate. Detailed Implementation

[0037] The following provides a detailed description of a method for implementing the present invention (hereinafter sometimes simply referred to as "this embodiment"). This embodiment is illustrative of the invention and is not intended to limit the invention to the following content. The invention can be implemented with appropriate modifications within its scope.

[0038] In this specification, "polyisocyanate" refers to a polymer composed of multiple monomers having two or more isocyanate groups (-NCO).

[0039] In this specification, "polyol" refers to a compound having two or more hydroxyl groups (-OH).

[0040] <Coating Compositions for Substrates>

[0041] This embodiment is a coating composition for a substrate used to form a multilayer coating laminate on a substrate.

[0042] More specifically, the substrate composition of this embodiment is a material used to form a first coating film in contact with the coating material when forming a multilayer coating laminate on the coating material.

[0043] In the following text, the layer formed by the coating composition for the substrate will be referred to as the “substrate layer” or the “first coating”.

[0044] By forming a base layer using the substrate composition of this embodiment on the substrate and further laminating a coating film on the base layer, a multilayer coating laminate with excellent hardness and water resistance can be manufactured even when curing at low temperatures.

[0045] In this embodiment, the multilayer coating laminate has a base layer and one or more coating layers.

[0046] An example of a multilayer coating laminate is a laminate in which a base layer of a first coating and a second coating are stacked sequentially.

[0047] An example of a multilayer coating laminate is a laminate in which a base layer, a second coating, and a third coating are stacked sequentially.

[0048] The second and third coatings in the above multilayer coating laminate example will be described later.

[0049] The substrate coating composition of this embodiment includes a polyisocyanate component (A) and a hydroxyl-containing resin component.

[0050] The substrate coating composition of this embodiment meets specific requirements, thereby achieving good dispersion stability and reducing the likelihood of isocyanate groups reacting with water, thus improving the pot life.

[0051] It should be noted that dispersion stability refers to a state in which the dispersion state is not easily changed over time and is not easily separated by sedimentation or other processes even as time passes.

[0052] The composition of the substrate coating composition of this embodiment will be described in detail.

[0053] Polyisocyanate components (A)

[0054] The polyisocyanate component (A) used in the substrate coating composition of this embodiment contains a polyisocyanate containing a sulfonate anion group and a tertiary ammonium cation of an amine compound.

[0055] The polyisocyanate component (A) contains one or more tertiary ammonium cations of amine compounds represented by the following general formula (1). Sometimes the amine compound represented by the following general formula (1) is referred to as "amine compound (1)".

[0056]

[0057] (In general formula (1), R) 11 R 12 and R 13 Independently, each group consists of a hydrocarbon group containing an ether bond and having 1 or more but fewer than 10 carbon atoms. The group is selected from R. 11 R 12 and R 13 At least one of the groups may optionally contain a ring structure, chosen freely from R. 11 R 12 and R 13 Two or more of the constituent elements can be optionally bonded together to form a ring structure. The aforementioned ring structure can be an aromatic ring, a cycloalkyl group with 5 or 6 carbon atoms, or an R-shaped ring. 11 With R 12 5-membered rings or 6-membered rings, or R-shaped rings formed by mutual bonding 11 With R 12 With R 13 (Multi-ringed structures formed by mutual bonding.)

[0058] The polyisocyanate component (A) enhances the dispersibility and stability of the substrate coating composition by including a polyisocyanate containing a sulfonate anion group and a tertiary ammonium cation of an amine compound. Furthermore, the monolayer first coating film formed from the substrate coating composition and the multilayer coating film laminate having the first coating film exhibit excellent hardness. In other words, both the dispersibility and stability of the substrate coating composition and excellent hardness are achieved.

[0059] [Polyisocyanate component (A)]

[0060] The polyisocyanate component (A) typically includes unmodified polyisocyanates, i.e., polyisocyanates that do not contain sulfonate anionic groups within their molecules. Furthermore, the various properties of the substrate coating composition of this embodiment described later, unless otherwise stated, encompass properties of both polyisocyanates containing sulfonate anionic groups within their molecules and unmodified polyisocyanates (polyisocyanates that do not contain sulfonate anionic groups within their molecules).

[0061] Furthermore, the ratio of unreacted polyisocyanate in polyisocyanate component (A) to polyisocyanate containing sulfonate anionic groups in the molecule can be calculated, for example, by the ratio of isocyanate groups containing sulfonate anionic groups in the molecule to 100 molar amounts of isocyanate groups in the raw material polyisocyanate.

[0062] [Polyisocyanates containing sulfonate anionic groups within their molecules]

[0063] The polyisocyanate component (A) contains a sulfonate anion group in its molecule. The polyisocyanate is a reaction product obtained by reacting a sulfonic acid or its amine salt with an active hydrogen group with the polyisocyanate.

[0064] (Polyisocyanates)

[0065] The polyisocyanate used in polyisocyanates containing an intramolecular sulfonate anionic groups is not particularly limited, and examples include polyisocyanates derived from at least one diisocyanate selected from the group consisting of aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates. From the viewpoint of easy industrial availability, the polyisocyanate used in polyisocyanates containing an intramolecular sulfonate anionic groups is preferably at least one selected from the group consisting of aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates, and more preferably an aliphatic polyisocyanate.

[0066] As an aliphatic diisocyanate, there are no particular limitations, and examples include 1,4-diisocyanate butane, 1,5-diisocyanate pentane (PDI), ethyl (2,6-diisocyanate)hexanoate, 1,6-diisocyanate hexane (hereinafter also referred to as "HDI"), 1,9-diisocyanate nonane, 1,12-diisocyanate dodecane, 2,2,4- or 2,4,4-trimethyl-1,6-diisocyanate hexane, etc.

[0067] As an alicyclic diisocyanate, there are no particular limitations, and examples include 1,3- or 1,4-bis(isocyanate methyl)cyclohexane (hereinafter also referred to as "hydrogenated XDI"), 1,3- or 1,4-diisocyanate cyclohexane, 3,5,5-trimethyl-1-isocyanate-3-(isocyanate methyl)cyclohexane (hereinafter also referred to as "IPDI"), 4-4'-diisocyanate-dicyclohexylmethane (hereinafter also referred to as "hydrogenated MDI"), 2,5- or 2,6-diisocyanate methyl norbornane, etc.

[0068] As an aromatic diisocyanate, there is no particular limitation; examples include phenylene diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate.

[0069] Among them, PDI, HDI, IPDI, hydrogenated XDI or hydrogenated MDI are preferred as diisocyanates, with PDI and HDI being particularly preferred.

[0070] There are no particular limitations on the polyisocyanates derived from the above-mentioned diisocyanates, and examples such as the polyisocyanates shown in (a) to (i) below can be cited.

[0071] (a) A polyisocyanate having a diuret group obtained by cyclizing and dimerizing two isocyanate groups;

[0072] (b) A polyisocyanate having an isocyanurate group or an iminooxadiazine dione group obtained by cyclizing and trimerizing three isocyanate groups;

[0073] (c) A polyisocyanate having a biuret group obtained by reacting three isocyanate groups with one water molecule;

[0074] (d) A polyisocyanate having an oxadiazine trione group obtained by reacting two isocyanate groups with one molecule of carbon dioxide;

[0075] (e) A polyisocyanate having multiple urethane groups obtained by reacting one isocyanate group with one hydroxyl group;

[0076] (f) A polyisocyanate having a urethane group obtained by reacting two isocyanate groups with one hydroxyl group;

[0077] (g) A polyisocyanate having an acylurea group obtained by reacting one isocyanate group with one carboxyl group;

[0078] (h) A polyisocyanate having a urea group obtained by reacting one isocyanate group with one primary or secondary amine.

[0079] (i) Polyisocyanates having an imino-oxadiazine dione group.

[0080] The polyisocyanate component (A) preferably comprises the urea diketone dimer of the above-mentioned diisocyanate and the isocyanurate trimer of the above-mentioned diisocyanate. That is, the polyisocyanate component (A) preferably comprises (a) and (b) above.

[0081] The polyisocyanate component (A) has isocyanurate groups, which makes the coating film have excellent hardness, water resistance, drying properties and weather resistance.

[0082] In addition, in the polyisocyanate component (A), the diuret group and the isocyanurate group can be contained in the same polyisocyanate molecule or in different polyisocyanate molecules, preferably in different polyisocyanate molecules.

[0083] In this embodiment, the content of urea diketone dimer is preferably 1.0% by mass or more and 20.0% by mass or less relative to the total mass of the polyisocyanate component (A), and the content of urea diketone dimer containing sulfonate anionic groups in the molecule is more preferably 0.15% by mass or less relative to the total mass of the polyisocyanate containing sulfonate anionic groups in the molecule, the urea diketone dimer and the isocyanurate trimer.

[0084] By keeping the urea diketone dimer within the above range, a multilayer coating laminate with good coating hardness can be obtained.

[0085] Furthermore, by setting the content of urea diketone dimers containing sulfonate anionic groups within the molecule to the above range, a multilayer coating laminate that combines excellent water resistance and stain resistance can be obtained.

[0086] It should be noted that the terms "urea diketone dimer of diisocyanate monomers" and "isocyanurate trimer of diisocyanate monomers" mentioned here refer to those that do not contain sulfonate anionic groups within the molecule (unmodified urea diketone dimer and isocyanurate trimer). Furthermore, "polyisocyanates containing sulfonate anionic groups within the molecule" include urea diketone dimers and isocyanurate trimers containing sulfonate anionic groups within the molecule.

[0087] The polyisocyanate component (A) preferably contains an iminooxadiazine dione group in addition to ureidone and isocyanurate groups.

[0088] In addition, the specific molar ratio shown in the following formula (2) is preferably 0.05 or more and 0.60 or less.

[0089] Specific molar ratio = (B+C) / (A+B+C)(2)

[0090] (In formula (2), A represents the content ratio (mol%) of the isocyanurate group shown in formula (I), B represents the content ratio (mol%) of the iminooxadiazine dione group shown in formula (II), and C represents the content ratio (mol%) of the urea dione group shown in formula (III).)

[0091]

[0092] The lower limit of the specific molar ratio shown in formula (2) is preferably 0.08, more preferably 0.12, even more preferably 0.15, even more preferably 0.18, and even more preferably 0.20. The upper limit of the specific molar ratio is preferably 0.50, more preferably 0.45, even more preferably 0.40, even more preferably 0.37, and even more preferably 0.35.

[0093] By setting the specific molar ratio above the aforementioned lower limit, excellent compatibility with hydroxyl-containing resin components can be achieved. Furthermore, by setting the specific molar ratio below the aforementioned upper limit, the hardness and other properties of the multilayer coating laminate are not easily degraded even when cured at low temperatures.

[0094] As a method for obtaining the polyisocyanate component (A) with a specific molar ratio of 0.05 or more and 0.60 or less as shown in formula (2), examples include methods for forming iminooxadiazine diketyl groups, urea diketyl groups, and urea formate groups by means of an iminooxadiazine diketylation reaction, a urea diketylation reaction, or a urea formate esterification reaction described later, and adjusting the specific molar ratio.

[0095] Regarding the molar ratio of the iminooxadiazine dione groups, the molar ratio of B / (A+B+C) (where A to C have the same meaning as A to C in formula (2) above) is preferably 0.05 or more and 0.60 or less. The lower limit of the above molar ratio is more preferably 0.08, further preferably 0.12, even more preferably 0.15, and even more preferably 0.18. The upper limit of the above molar ratio is more preferably 0.50, further preferably 0.45, even more preferably 0.40, and even more preferably 0.37.

[0096] By setting the above molar ratio to 0.05 or higher, there is a tendency to exhibit better compatibility with hydroxyl-containing resin components; by setting the above molar ratio to 0.60 or lower, there is a tendency to suppress the decline in coating performance during low-temperature curing.

[0097] From the viewpoint of obtaining a multilayer coating laminate with high hardness, the above molar ratio is more preferably 0.50 or less. As a method for obtaining the polyisocyanate component (A) with a molar ratio of 0.05 or more and 0.60 or less, examples include forming an iminooxadiazine diketone group by an iminooxadiazine diketation reaction described later and adjusting the above molar ratio.

[0098] From the viewpoint of improving resistance to acids, alkalis, and salt spray, and suppressing low viscosity and dilution turbidity, the polyisocyanate component (A) may contain the reaction product with the alcohol. That is, the polyisocyanate component (A) preferably contains one or both of the above (e) and (f).

[0099] The alcohols described above preferably have an average number of hydroxyl groups of 2.0 or more and 3.5 or less per molecule, and a number average molecular weight of 450 or less.

[0100] From the viewpoint of suppressing low viscosity and dilution turbidity while improving acid resistance, alkali resistance, and salt spray resistance, the lower limit of the average number of hydroxyl groups of the alcohol used in this embodiment is preferably 2.0 or more and 3.0 or less, and more preferably 2.0 or more and 2.5 or less. Furthermore, from the viewpoint of suppressing low viscosity, dispersibility, and coating hardness, the number average molecular weight is preferably 400 or less, and more preferably 350 or less.

[0101] Alcohols that satisfy the above-mentioned average number of hydroxyl groups and number-average molecular weight include diols, triols, and tetraols. 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, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, neopentanediol, 2-methyl-2,3-butanediol, 1,6-hexanediol, 1,2-hexanediol, 2,5-hexanediol, and 2-methyl- Examples of triols include 2,4-pentanediol, 2,3-dimethyl-2,3-butanediol, 3-methyl-1,5-pentanediol, 2-ethyl-hexanediol, 1,2-octanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 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. Examples of tetraols include pentaerythritol.

[0102] Examples of polymeric alcohols include polyester polyols, polyether polyols, acrylic polyols, polyolefin polyols, and polycarbonate diols.

[0103] Examples of polyester polyols include: polyester polyols obtained by condensation reaction of a dicarboxylic acid selected from the group consisting of succinic acid, adipic acid, sebacic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid, terephthalic acid, etc., alone or in mixtures, with a polyol selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, glycerol, etc.; and polycaprolactones, for example, obtained by ring-opening polymerization of ε-caprolactone using a polyol.

[0104] Polyether polyols include: polyether polyols obtained by random or block addition of ethylene oxide, propylene oxide, butane oxide, cyclohexene oxide, styrene oxide, etc., with polyhydroxy compounds, either alone or in mixtures, using strong alkaline catalysts such as hydroxides of lithium, sodium, potassium, etc., alkoxides, alkylamines, etc., and complex metal cyanide compound complexes such as metalloporphyrins and zinc hexacyanocobaltate complexes; furthermore, polyether polyols obtained by reacting ethylene oxide with polyamine compounds such as ethylenediamines; and so-called polymer polyols obtained by polymerizing acrylamide, etc., using these polyethers as a medium.

[0105] As a polycarbonate diol, it repeatedly has a structural unit formed by the dehydration condensation of two alcohol groups and one carbonate group. Alternatively, polycarbonate diols can be exemplified by copolymerizing a first diol having 2 or more but less than 20 carbon atoms and a second diol having 2 or more but less than 20 carbon atoms (hereinafter also simply referred to as "two diols") with a carbonate compound.

[0106] These alcohols can be used alone or in combination.

[0107] The mass percentage of alcohol relative to the total mass of the polyisocyanate component in this embodiment is preferably 0.01% by mass or more and 4.5% by mass or less. Furthermore, from the viewpoint of balancing dilution turbidity and the color, acid resistance, and salt spray resistance of the polyisocyanate component, it is even more preferably 0.1% by mass or more and 2.5% by mass or less.

[0108] Furthermore, polyisocyanates used in polyisocyanates containing sulfonate anionic groups within their molecules may include aliphatic triisocyanates. Examples of such aliphatic triisocyanates include 1,3,6-triisocyanate hexane, 1,8-diisocyanate-4-isocyanate-methyloctane, and 2-isocyanate-ethyl-2,6-diisocyanate-hexanoate.

[0109] In addition, these polyisocyanates can be modified by nonionic hydrophilic groups such as alkoxy polyalkylene glycols, and by vinyl polymers having hydroxyl and nonionic hydrophilic groups.

[0110] In addition, these polyisocyanates can be used alone or in combination of two or more.

[0111] When the polyisocyanate component (A) contains a polyisocyanate modified with a nonionic hydrophilic group, the content of the nonionic hydrophilic polyisocyanate is preferably 1% by mass or more and 60% by mass or less. The upper limit of the content of the nonionic hydrophilic polyisocyanate is preferably 60% by mass, more preferably 40% by mass, further preferably 30% by mass, and particularly preferably 20% by mass. The lower limit is preferably 2% by mass, more preferably 5% by mass, and further preferably 10% by mass. By setting the content of the nonionic hydrophilic polyisocyanate within the above range, the pot life of the coating composition for a substrate dispersed in water or an aqueous main agent becomes good, and a multilayer coating laminate with excellent water resistance is easily obtained.

[0112] (Nonionic hydrophilic group)

[0113] As a nonionic hydrophilic group, there is no particular limitation; examples include polyalkylene glycol alkyl ethers. From the viewpoint of reducing the viscosity of the coating composition for the substrate, the polyalkylene glycol alkyl ether preferably has one hydroxyl group.

[0114] Preferred polyalkylene glycol alkyl ethers have the structure shown in the following general formula (20).

[0115]

[0116] In general formula (20), R 21 R is an alkylene group having 1 or more carbon atoms and 4 or fewer carbon atoms. 22 It is an alkyl group with 1 or more carbon atoms and 4 or fewer carbon atoms, and n11 is 4.0 or more and 20 or fewer carbon atoms.

[0117] Polyalkylene glycol alkyl ethers are not single components, but rather an aggregate of substances with different values ​​for the degree of polymerization n (hereinafter sometimes referred to as "degree of polymerization n" or simply "n"). Therefore, the degree of polymerization n is expressed as its average value. In equation (20), the degree of polymerization n is recorded as n11.

[0118] When polyisocyanates are incorporated into aqueous base agents, thickening during mixing often becomes a problem. Excessive thickening can lead to uneven dispersion of the polyisocyanate in the base agent, resulting in a decrease in the physical properties of the coating film.

[0119] Therefore, from the viewpoint of water dispersibility and dispersibility in the main agent, n11 is 4.0 or more and 20 or less, preferably 4.0 or more and 16 or less, and more preferably 4.0 or more and 12 or less. By setting n11 to the lower limit value or above, there is a tendency for improved dispersibility due to increased emulsifying power; on the other hand, by setting it to the upper limit value or below, there is a tendency for easy dispersion due to prevention of viscosity increase.

[0120] Two or more polyalkylene glycol alkyl ethers with different n values ​​can also be used in combination. The n value of polyalkylene glycol alkyl ethers can be determined by proton nuclear magnetic resonance (NMR).

[0121] R in general formula (I) 21 From the viewpoint of imparting hydrophilicity, alkylene groups having 1 or more but less than 4 carbon atoms are preferred; from the viewpoint of being able to further impart hydrophilicity, ethylene groups having 2 carbon atoms are preferred.

[0122] Additionally, R 22 From the viewpoint of imparting hydrophilicity, alkyl groups having 1 or more but less than 4 carbon atoms are preferred; from the viewpoint of being able to further impart hydrophilicity, methyl groups having 1 carbon atom are preferred.

[0123] As a polyalkylene glycol alkyl ether, examples include, but are not limited to, polyethylene glycol (mono) methyl ether, poly(ethylene, propylene) glycol (mono) methyl ether, and polyethylene glycol (mono) ethyl ether. Among these, polyethylene glycol (mono) methyl ether is preferred from the viewpoint of imparting hydrophilicity.

[0124] (Manufacturing method of polyisocyanates)

[0125] (I) Method for manufacturing polyisocyanates containing isocyanurate groups

[0126] There are no particular limitations on the method for manufacturing polyisocyanates containing isocyanurate groups. Examples include methods that use isocyanurate esterification catalysts and alcohols as co-catalysts to react diisocyanate monomers.

[0127] Examples of isocyanurate esterification catalysts used in the manufacture of isocyanurate-type polyisocyanates include sodium salts, potassium salts, and quaternary ammonium salts of fatty acids.

[0128] Examples of fatty acids include acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, caprylic acid, nonanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, and stearic acid. Furthermore, these fatty acids can be linear or branched.

[0129] Examples of quaternary ammonium compounds include tetramethylammonium, tetrabutylammonium, butyltrimethylammonium, benzyltrimethylammonium, dibenzyldimethylammonium, and phenyltrimethylammonium.

[0130] The amount of isocyanurate esterification catalyst varies depending on the amount of co-catalyst and solvent. Generally, when using HDI as a raw material for polyisocyanates, the amount relative to the mass of HDI can be set to more than 0.001% by mass and less than 0.05% by mass.

[0131] Regarding the alcohol used as a cocatalyst, phenolic hydroxyl compounds or alcoholic hydroxyl compounds can be used, for example. This makes the isocyanurate esterification reaction easier to proceed.

[0132] Examples of phenolic hydroxyl compounds include phenol, cresol, and trimethylphenol.

[0133] Examples of alcoholic hydroxyl compounds include straight-chain alcohols, branched-chain alcohols, cyclic alcohols, and polyols.

[0134] Examples of straight-chain alcohols include methanol, ethanol, propanol, n-butanol, and 1-hexanol.

[0135] Examples of branched alcohols include isobutanol and 2-ethylhexanol.

[0136] Examples of cyclic alcohols include cyclohexanol.

[0137] Examples of polyols include ethylene glycol.

[0138] The amount of alcohol used is related to the amount of urea ester groups present in the polyisocyanate component. When using HDI as a raw material for polyisocyanate, it is preferable to use an amount of 500 ppm or more and 30,000 ppm or less by mass relative to HDI. By keeping the amount of alcohol below the upper limit mentioned above, the proportion of isocyanurate groups in the final polyisocyanate component can be appropriately maintained, resulting in better weather resistance and chemical resistance. On the other hand, by keeping the amount of alcohol above the lower limit mentioned above, a higher reaction rate can be maintained, resulting in better productivity in terms of economy.

[0139] In the production of isocyanurate-type polyisocyanates, the alcohol is added at a time that ensures it is present in the reaction system during the isocyanuration reaction. Specifically, it can be added at any of the following times: before the isocyanuration reaction, simultaneously with the isocyanuration catalyst, or during the isocyanuration reaction after the addition of the isocyanuration catalyst. Furthermore, it can be added at any one of these times, or at all of them. The alcohol can be added in a single step or continuously. From the viewpoint of controlling the reaction and exothermic reaction, continuous addition is preferred for alcohol addition during the isocyanuration reaction. For alcohol addition before the isocyanuration reaction, a single step is preferred from an economic perspective.

[0140] The isocyanurate esterification reaction temperature is preferably 70°C or lower, more preferably 30°C or higher and 65°C or lower. By setting the isocyanurate esterification reaction temperature below the upper limit mentioned above, a polyisocyanate with better color can be obtained. On the other hand, by setting the isocyanurate esterification reaction temperature above the lower limit mentioned above, the reaction rate can be maintained more appropriately, resulting in better productivity in terms of economy.

[0141] The reaction time varies depending on the amount of catalyst, the amount and method of adding alcohol as a co-catalyst, and the reaction temperature, and can usually be set to more than 1 hour and less than 6 hours.

[0142] The decrease in isocyanate group content (NCO%) that occurs during isocyanurate esterification can be determined by titration analysis; therefore, the reaction can be stopped when the specified NCO% is reached.

[0143] The NCO% and viscosity of isocyanurate-type polyisocyanates can be freely changed by adjusting the NCO% at which the reaction stops.

[0144] Acidic compounds can be used as reaction terminators. Examples of acidic compounds include hydrochloric acid, phosphoric acid, dimethyl phosphate, diethyl phosphate, dibutyl phosphate, di-2-ethylhexyl phosphate, dicyclohexyl phosphate, p-toluenesulfonic acid, benzenesulfonic acid, alkylbenzenesulfonic acid, acetyl chloride, benzoyl chloride, etc. Additionally, similar compounds to these acidic compounds can also be used.

[0145] The amount of the reaction terminator used, relative to 1 mole of carboxylic acid content in the isocyanurate esterification catalyst, can be set to 0.5 times or more and 10 times or less, preferably 1 time or more and 8 times or less. When using a reaction terminator that is soluble in a mixed solution of the diisocyanate monomer as a raw material and the polyisocyanate generated in the reaction, it can be set to about 1 time or more relative to 1 mole of carboxylic acid content in the isocyanurate esterification catalyst. When using an insoluble reaction terminator, it can be set to 2 times or more and 8 times or less relative to 1 mole of carboxylic acid content in the isocyanurate esterification catalyst.

[0146] After the reaction terminator is added, heating and aging can be performed to completely stop the reaction. The heating and aging temperature is preferably 80°C or higher and 150°C or lower, more preferably 80°C or higher and 130°C or lower, and even more preferably 90°C or higher and 120°C or lower. By keeping the temperature below the upper limit mentioned above, the reduction of 1-nylon bodies in the polyisocyanate component containing the obtained isocyanurate-type polyisocyanate can be further suppressed. Furthermore, the decrease in color and the increase in viscosity caused by the polymerization of the isocyanurate-type polyisocyanate can be further suppressed. By keeping the temperature above the lower limit mentioned above, the growth of salts formed by stopping the reaction can be accelerated. Especially in the case of a combination of a catalyst that forms insoluble salts and a reaction terminator, salts of filterable size can be further formed, thus resulting in better productivity in terms of economy.

[0147] Regarding the heating and curing time, the optimal time varies depending on the temperature, and can be set to 10 minutes or more and 120 minutes or less, preferably 10 minutes or more and 90 minutes or less, and more preferably 10 minutes or more and 60 minutes or less. Although it also depends on the temperature, by keeping the time below the aforementioned upper limit, coloring and high viscosity caused by further polymerization of polyisocyanates can be further suppressed. On the other hand, by keeping the time above the aforementioned lower limit, salt formation and growth can be more complete, and in the case of insoluble salts, separation by filtration can be easier.

[0148] (II) Method for manufacturing polyisocyanates containing urea diketone groups

[0149] There are no particular limitations on the method for manufacturing polyisocyanates containing urea diketone groups. Examples include methods that use urea diketone catalysts to carry out urea diketone reactions on diisocyanates.

[0150] As catalysts for ureidodiketation reactions, examples include, but are not limited to, trialkylphosphine, tris(dialkylamino)phosphine, cycloalkylphosphine, and other tertiary phosphines.

[0151] Examples of trialkylphosphines include tri-n-butylphosphine and tri-n-octylphosphine.

[0152] Examples of tris(dialkylamino)phosphine include tri-(dimethylamino)phosphine and other tris(dialkylamino)phosphine.

[0153] Examples of cycloalkylphosphines include cyclohexyl-di-n-hexylphosphine.

[0154] Most of these compounds also promote isocyanurate esterification reactions, generating isocyanurate-type polyisocyanates in addition to polyisocyanates containing urea diketone groups.

[0155] When the desired yield is achieved, phosphoric acid, methyl p-toluenesulfonate, or other deactivators of the ureidodiketation catalyst are added to stop the ureidodiketation reaction.

[0156] Alternatively, instead of using the ureidodiketation catalyst described above, a polyisocyanate containing a ureidodiketone group can be obtained by heating the diisocyanate monomer.

[0157] When the above-mentioned ureidodiketation reaction catalyst is not used, the heating temperature can be set to 120°C or higher, preferably 150°C or higher and 170°C or lower. Furthermore, the heating time can be set to 1 hour or more and 4 hours or less.

[0158] (III) Iminooxadiazineation reaction to form an iminooxadiazine dione group

[0159] As a catalyst for the iminooxadiazine ketation reaction that forms an iminooxadiazine dione group, catalysts such as those described below (1) and (2) that are commonly used as catalysts for iminooxadiazine ketation can be used, for example.

[0160] (1) Hydrogen fluoride (poly)fluoride represented by general formula M[Fn] or general formula M[Fn(HF)m], such as tetramethylammonium fluoride hydrate and tetraethylammonium fluoride (where m and n are integers satisfying the relationship m / n>0, and M represents a cation (mixture) with n charge or one or more free radicals with a total valence of n).

[0161] (2) Compounds formed by 3,3,3-trifluorocarboxylic acid, 4,4,4,3,3-pentafluorobutyric acid, 5,5,5,4,4,3,3-heptafluoropentanoic acid, 3,3-difluoroprop-2-enoic acid, etc., with the general formula R1-CR'2-C(O)O- or general formula R2=CR'-C(O)O- (where R1 and R2 represent, as needed, branched, cyclic and / or unsaturated perfluoroalkyl groups having 1 to 30 carbon atoms, and R', whether the same or different, represent groups selected from the group consisting of hydrogen atoms, alkyl groups having 1 to 20 carbon atoms, and aryl groups, containing heteroatoms as needed.) with quaternary ammonium cations or quaternary phosphonium cations.

[0162] From the perspective of ease of acquisition, the above (1) is preferred; from the perspective of security, the above (2) is preferred.

[0163] The amount of these catalysts relative to the mass of the added diisocyanate is preferably 10 ppm by mass or more and 1000 ppm by mass or less. The lower limit is more preferably 20 ppm by mass, further preferably 40 ppm by mass, and even more preferably 80 ppm by mass. The upper limit is more preferably 800 ppm by mass, further preferably 600 ppm by mass, and even more preferably 500 ppm by mass or less.

[0164] Furthermore, the reaction temperature is preferably 40–120°C. The lower limit of the reaction temperature is more preferably 50°C, and even more preferably 55°C. The upper limit of the reaction temperature is more preferably 100°C, even more preferably 90°C, and even more preferably 80°C. By setting the reaction temperature to 40°C or higher, there is a tendency to maintain a relatively high reaction rate; by setting the reaction temperature to 120°C or lower, there is a tendency to suppress the coloring of the polyisocyanate.

[0165] (IV) Method for manufacturing polyisocyanates containing urea carbamate groups

[0166] Polyisocyanates having urea-formate groups (polyisocyanates containing urea-formate groups) can be obtained by combining an alcohol compound or the like with a diisocyanate and using a urea-formate esterification catalyst.

[0167] As for alcohol compounds used to manufacture polyisocyanates containing urea-formate groups, alcohols formed solely of carbon, hydrogen, and oxygen are preferred, but not limited to these examples. Furthermore, the molecular weight of the alcohol compound is preferably 200 or less.

[0168] Examples of alcohol compounds include monohydric alcohols and dihydric alcohols.

[0169] Examples of monohydric alcohols include methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, and nonanol.

[0170] Examples of diols include ethylene glycol, 1,3-butanediol, neopentyl glycol, and 2-ethylhexanediol.

[0171] These alcohol compounds can be used alone or in combination of two or more.

[0172] Among them, monohydric alcohols are preferred as alcohol compounds.

[0173] Regarding the amount of alcohol compound used, it is not limited to the following, but preferably 10 / 1 or more and 1000 / 1 or less, more preferably 100 / 1 or more and 1000 / 1 or less, based on the molar ratio of the isocyanate group of HDI to the hydroxyl group of the alcohol compound. By using a value above the above lower limit, a more suitable average number of isocyanate groups can be ensured in the obtained polyisocyanates.

[0174] Catalysts for urea carbamate reactions include, but are not limited to, alkyl carboxylates such as tin, lead, zinc, bismuth, zirconium, and zirconium oxycarboxylate.

[0175] Examples of alkyl carboxylates (organotin compounds) of tin include tin 2-ethylhexanoate and dibutyltin dilaurate.

[0176] Examples of alkyl carboxylates (organolead compounds) of lead include lead 2-ethylhexanoate.

[0177] Examples of alkyl carboxylates (organozinc compounds) of zinc include zinc 2-ethylhexanoate.

[0178] Examples of alkyl carboxylates of bismuth include bismuth 2-ethylhexanoate.

[0179] Examples of alkyl carboxylates of zirconium include zirconium 2-ethylhexanoate.

[0180] Examples of alkyl carboxylate salts of zirconium oxyoxide include, for example, zirconium oxy2-ethylhexanoate.

[0181] When the desired yield is achieved, deactivators of the urea-formylation catalyst, such as phosphoric acid or methyl p-toluenesulfonate, can be added to stop the urea-formylation reaction.

[0182] Regarding the amount of the catalyst used in the urea-formylation reaction, it is preferably 10 ppm or more and 10,000 ppm or less by mass relative to the diisocyanate used as a raw material, more preferably 10 ppm or more and 1,000 ppm or less, and even more preferably 10 ppm or more and 500 ppm or less.

[0183] The lower limit of the reaction temperature for urea-formylation is preferably 60°C, more preferably 70°C, even more preferably 80°C, and particularly preferably 90°C. On the other hand, the upper limit of the reaction temperature for urea-formylation is preferably 160°C, more preferably 155°C, even more preferably 150°C, and particularly preferably 145°C.

[0184] That is, the reaction temperature for urea-formylation is preferably 60°C or higher and 160°C or lower, more preferably 70°C or higher and 155°C or lower, even more preferably 80°C or higher and 150°C or lower, and particularly preferably 90°C or higher and 145°C or lower.

[0185] By setting the urea-formylation reaction temperature below the aforementioned upper limit, changes in the coloring and other properties of the resulting polyisocyanate can be prevented more effectively.

[0186] The lower limit of the reaction time is preferably 0.2 hours, more preferably 0.4 hours, further preferably 0.6 hours, particularly preferably 0.8 hours, and most preferably 1.0 hour. On the other hand, the upper limit of the reaction time is preferably 8 hours or less, more preferably 6 hours, further preferably 4 hours, particularly preferably 3 hours, and most preferably 2 hours.

[0187] That is, the reaction time for urea-formylation is preferably 0.2 hours or more and 8 hours or less, more preferably 0.4 hours or more and 6 hours or less, even more preferably 0.6 hours or more and 4 hours or less, particularly preferably 0.8 hours or more and 3 hours or less, and most preferably 1.0 hours or more and 2 hours or less.

[0188] By setting the reaction time for urea-formylation above the aforementioned lower limit, its viscosity can be reduced. By setting it below the aforementioned upper limit, the coloring of the polyisocyanate itself can be further suppressed.

[0189] Alternatively, the above-mentioned isocyanurate esterification catalyst can be used as a catalyst for ureacarboxylation. When the above-mentioned isocyanurate esterification catalyst is used for ureacarboxylation, isocyanurate-type polyisocyanates are also generated simultaneously. From the viewpoint of improving productivity from an economic perspective, it is preferable to use the above-mentioned isocyanurate esterification catalyst as a catalyst for both ureacarboxylation and isocyanurate esterification.

[0190] The above-mentioned isocyanurate esterification reaction and the above-mentioned ureidodiketation reaction can be carried out sequentially or in parallel.

[0191] In addition, the manufacturing process can be simplified by accompanying the urea-formylation reaction. Therefore, it is preferable to perform the isocyanurate esterification reaction and the urea-formylation reaction in parallel first, followed by the urea-diketone reaction.

[0192] The urea-formylation reaction can be stopped when the desired urea-formyl group content is reached.

[0193] Urea formate esterification reactions can be stopped, for example, by adding acidic compounds such as phosphoric acid, acid phosphates, sulfuric acid, hydrochloric acid, or sulfonic acid compounds to the reaction solution, but are not limited to these methods. Thus, the catalyst for the urea formate esterification reaction can be deactivated through neutralization, thermal decomposition, or chemical decomposition. After the reaction is stopped, filtration can be performed as needed.

[0194] (V) Thin-film distillation process and heat treatment process

[0195] The reaction solution immediately after the reaction has stopped usually contains unreacted diisocyanate monomers such as HDI, so it is preferable to remove them using a thin-film evaporator or extraction.

[0196] Thin-film distillation is a process used to improve the separation efficiency of low-boiling-point components from high-boiling-point components. Specific countermeasures include, for example, reducing the flow rate to extend the residence time, increasing the distillation temperature, increasing the scraper rotation speed, and increasing the number of distillations; any method can be selected. Among these, increasing the number of distillations is preferred from the perspective of reducing the thermal path and improving separation efficiency. The number of distillations is preferably one to five.

[0197] It should be noted that the content of residual diisocyanate monomer in the polyisocyanate component is preferably 0.50% by mass or less, more preferably 0.40% by mass or less, further preferably 0.30% by mass or less, particularly preferably 0.20% by mass or less, and most preferably 0.10% by mass or less.

[0198] By keeping the residual diisocyanate monomer content in the polyisocyanate component below the aforementioned upper limit, the toxicity of the polyisocyanate component can be further reduced, and its safety can be further improved. Furthermore, by keeping it below 0.10% by mass, a multilayer coating with an exceptionally superior final appearance can be obtained.

[0199] (Sulfonic acids with active hydrogen groups)

[0200] In polyisocyanates containing sulfonate anionic groups, sulfonic acids with active hydrogen groups can be categorized as having active hydrogen groups, such as amino, carboxyl, and hydroxyl groups. Preferably, at least one active hydrogen group is selected from the group consisting of free amino and hydroxyl groups, and more preferably, at least one active hydrogen group is selected from the group consisting of free hydroxyl groups.

[0201] (Sulfonic acid(4))

[0202] When the active hydrogen group is a hydroxyl group, sulfonic acids having a hydroxyl group can be listed as compounds represented by the following general formula (4) (hereinafter referred to as "sulfonic acid (4)").

[0203] HO—R 41 —SO3H (4)

[0204] In the above general formula (4), R 411 R is a hydrocarbon group consisting of at least one of the groups selected from hydroxyl, ether, ester, carbonyl, and imino, having 1 or more carbon atoms and less than 10 carbon atoms. 41 The ring structure can be optionally included. The above ring structure is an aromatic ring, a 5-membered or 6-membered ring containing 2 nitrogen atoms, or a 5-membered or 6-membered ring containing nitrogen and oxygen atoms.

[0205] ·R 41

[0206] In general formula (4), R 41It is a hydrocarbon group with 1 or more carbon atoms selected from the group consisting of at least one of the following: hydroxyl, ester bond (-COO-), ether bond (-O-), carbonyl group (-C(=O)-), imino group (-NR-), and ring structure.

[0207] The hydrocarbon group having 1 or more but less than 10 carbon atoms can be a divalent aliphatic hydrocarbon group having 1 or more but less than 10 carbon atoms, or a divalent aromatic hydrocarbon group having 6 or more but less than 10 carbon atoms. As a divalent aliphatic hydrocarbon group having 1 or more but less than 10 carbon atoms, a chain-like alkylene group having 1 or more but less than 6 carbon atoms is preferred. When it is a chain-like alkylene group having 1 or more but less than 6 carbon atoms, a group containing a ring structure in a portion of the chain-like alkylene group may be present. The alkylene group having 1 or more but less than 6 carbon atoms can be straight-chain or branched.

[0208] Among them, as R 41 Preferably, the alkylene group is a chain with 1 or more but less than 6 carbon atoms, an aromatic hydrocarbon group (arylene) with 6 or more but less than 10 carbon atoms in divalent form, an alkylene group with 1 or more but less than 6 carbon atoms in divalent form containing an aromatic ring, an alkylene group with 1 or more but less than 6 carbon atoms in divalent form containing a 5-membered ring or a 6-membered ring containing 2 nitrogen atoms, or an alkylene group with 1 or more but less than 6 carbon atoms in divalent form containing a 5-membered ring or a 6-membered ring containing nitrogen and oxygen atoms.

[0209] Preferred examples of sulfonic acids (4) include, for example, 2-hydroxyethanesulfonic acid, 3-hydroxypropanesulfonic acid, 4-hydroxybutyric acid, 5-hydroxypentanesulfonic acid, 6-hydroxyhexanesulfonic acid, hydroxybenzenesulfonic acid, hydroxy(methyl)benzenesulfonic acid, 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, 4-(2-hydroxyethyl)-1-piperazinepropanesulfonic acid, 2-hydroxy-3-morpholinopropanesulfonic acid, etc.

[0210] It should be noted that these compounds are only a part of the preferred sulfonic acid (4), and the preferred sulfonic acid (4) is not limited to these.

[0211] In addition, these sulfonic acids (4) can be used in one form or in combination of two or more.

[0212] Among them, the sulfonic acid having a hydroxyl group is preferably at least one selected from the group consisting of 2-hydroxyethanesulfonic acid, 3-hydroxypropanesulfonic acid, hydroxybenzenesulfonic acid, and hydroxy(methyl)benzenesulfonic acid.

[0213] It should be noted that when the base coating composition of this embodiment contains amine salts of two or more sulfonic acids, the sulfonic acids (4) may be the same or different from each other.

[0214] In addition, the sulfonic acid used in polyisocyanates containing sulfonate anionic groups in the molecule can form salts with amine compounds described later.

[0215] (Sulfonic acid(5))

[0216] When the active hydrogen group is amino, sulfonic acids having an amino group can be listed as compounds represented by the following general formula (5) (hereinafter referred to as "sulfonic acid (5)").

[0217]

[0218] In the above general formula (5), R 51 and R 53 Each of the following is an independent hydrogen atom or an optional hydrocarbon group containing a hydroxyl group and having 1 or more but less than 12 carbon atoms. R 51 and R 53 At least one of them is a hydrogen atom. R 52 It can be any hydrocarbon group containing a hydroxyl group with 1 or more but less than 12 carbon atoms.

[0219] ·R 51 and R 53

[0220] In general formula (5), R 51 and R 53 Each of the following is an independent hydrogen atom or an optional hydrocarbon group containing a hydroxyl group and having 1 or more but less than 12 carbon atoms. R 51 and R 53 They can be the same or different. R 51 and R 53 At least one of them is a hydrogen atom. That is, R 51 When R is any hydrocarbon group containing a hydroxyl group and having 1 or more but fewer than 12 carbon atoms, 53 It is a hydrogen atom. Additionally, R... 53 When R is any hydrocarbon group containing a hydroxyl group and having 1 or more but fewer than 12 carbon atoms, 51 It is a hydrogen atom. Alternatively, it could be R. 51 and R 53 All are hydrogen atoms.

[0221] The hydrocarbon group having 1 or more but less than 12 carbon atoms can be an aliphatic hydrocarbon group with 1 or more but less than 12 carbon atoms in a monovalent state, or an aromatic hydrocarbon group with 6 or more but less than 12 carbon atoms in a monovalent state. Preferably, the aliphatic hydrocarbon group having 1 or more but less than 12 carbon atoms in a chain alkyl group, or a cyclic alkyl group having 3 or more but less than 6 carbon atoms in a monovalent state, is a linear alkyl group. The linear alkyl group having 1 or more but less than 6 carbon atoms in a chain can be straight-chain or branched.

[0222] Among them, as R 51 and R 53 Preferably, they are hydrogen atoms, chain alkyl groups with 1 or more carbon atoms and 6 or fewer carbon atoms, or cyclic alkyl groups with 3 or more carbon atoms and 6 or fewer carbon atoms.

[0223] ·R 52

[0224] R 52 It can be any hydrocarbon group containing a hydroxyl group with 1 or more but less than 12 carbon atoms.

[0225] The hydrocarbon group having 1 or more but 12 or fewer carbon atoms can be an aliphatic hydrocarbon group with 1 or more but 12 or fewer carbon atoms, or an aromatic hydrocarbon group with 6 or more but 12 or fewer carbon atoms, both valent in divalent form. Preferably, the aliphatic hydrocarbon group having 1 or more but 12 or fewer carbon atoms is a chain-like alkylene group. The chain-like alkyl group having 1 or more but 12 or fewer carbon atoms can be straight-chain or branched.

[0226] Among them, as R 52 Preferably, it is a chain alkylene group with 1 or more carbon atoms and 6 or less in a divalent state, or an aromatic hydrocarbon group (arylene group) with 6 or more carbon atoms and 10 or less in a divalent state.

[0227] Preferred examples of sulfonic acids (5) include, for example, 2-aminoethanesulfonic acid, 3-aminopropanesulfonic acid, 2-methylaminoethanesulfonic acid, 3-methylaminopropanesulfonic acid, 2-cyclohexylaminoethanesulfonic acid, 3-cyclohexylaminopropanesulfonic acid, 3-cyclohexylaminoisobutylsulfonic acid, 4-cyclohexylaminobutyric acid, 2-cyclohexylmethylaminoethanesulfonic acid, 3-cyclohexylmethylaminopropanesulfonic acid, 3-cyclohexylmethylaminoisobutylsulfonic acid, 4-cyclohexylmethylaminobutyric acid, 2-methylcyclohexylaminoethanesulfonic acid, 3-methylcyclohexylaminopropanesulfonic acid, 3-methylcyclohexylaminoisobutylsulfonic acid, 4-methylcyclohexylaminobutyric acid, 2-methylcyclohexylaminoethanesulfonic acid, 3-methylcyclohexylaminopropanesulfonic acid, 3-methylcyclohexylaminoisobutylsulfonic acid, 4-methylcyclohexylaminobutyric acid. Sulfonic acid, 2-dimethylcyclohexylaminoethanesulfonic acid, 3-dimethylcyclohexylaminopropanesulfonic acid, 3-dimethylcyclohexylaminoisobutylsulfonic acid, 4-dimethylcyclohexylaminobutyric acid, 2-trimethylcyclohexylaminoethanesulfonic acid, 3-trimethylcyclohexylaminopropanesulfonic acid, 3-trimethylcyclohexylaminoisobutylsulfonic acid, 4-trimethylcyclohexylaminobutyric acid, 2-aminobenzenesulfonic acid, 3-aminobenzenesulfonic acid, 4-aminobenzenesulfonic acid, 2-(methylamino)benzenesulfonic acid, 3-(methylamino)benzenesulfonic acid, 4-(methylamino)benzenesulfonic acid, amino-methylbenzenesulfonic acid, amino-dimethylbenzenesulfonic acid, aminonaphthalenesulfonic acid, etc.

[0228] It should be noted that these compounds are only a part of the preferred sulfonic acids (5), and the preferred sulfonic acids (5) are not limited to these.

[0229] In addition, these sulfonic acids (5) can be used in one form or in combination of two or more.

[0230] The sulfonic acid having an amino group is preferably selected from at least one of the following: 2-cyclohexylaminoethanesulfonic acid, 3-cyclohexylaminopropanesulfonic acid, 4-cyclohexylaminobutyric acid, 3-cyclohexylmethylaminopropanesulfonic acid, 3-(p-methylcyclohexylamino)propanesulfonic acid, 3-(3,3,5-trimethylcyclohexylamino)propanesulfonic acid, 4-(p-methylcyclohexylamino)butyric acid, 2-aminobenzenesulfonic acid, 2-amino-5-methylbenzenesulfonic acid, 2-amino-3,5-dimethylbenzenesulfonic acid, 5-amino-2-methylbenzenesulfonic acid (4-aminotoluene-2-sulfonic acid), 4-amino-2-methylbenzenesulfonic acid (5-aminotoluene-2-sulfonic acid), and 2-aminonaphthalene-4-sulfonic acid.

[0231] It should be noted that when the base coating composition of this embodiment contains amine salts of two or more sulfonic acids, the sulfonic acids (5) may be the same or different from each other.

[0232] [Amine compounds]

[0233] The polyisocyanate component (A) contains one or more tertiary ammonium cations of amine compounds represented by the following general formula (1).

[0234] It should be noted that the "tertiary ammonium cation of amine compounds" referred to here means: through the transformation of protons (H... + It is formed by coordinating with the "N" in the amine compound shown by the following general formula (1) and thus undergoing protonation.

[0235] In addition, in the polyisocyanate component (A), the amine compound can form a salt with the aforementioned sulfonic acid.

[0236]

[0237] In the above general formula (1), R 11 R 12 and R 13 Independently, each group consists of a hydrocarbon group containing an ether bond and having 1 or more but fewer than 10 carbon atoms. The group is selected from R. 11 R 12 and R 13 At least one of the groups may optionally contain a ring structure, chosen freely from R. 11 R 12 and R 13 Two or more of the constituent elements can be optionally bonded together to form a ring structure. The aforementioned ring structure can be an aromatic ring, a cycloalkyl group with 5 or 6 carbon atoms, or an R-shaped ring. 11 With R 12 5-membered rings or 6-membered rings, or R-shaped rings formed by mutual bonding 11 With R 12 With R 13 A multi-ringed structure formed by mutual bonding.

[0238] ·R 11 R 12 and R 13

[0239] R 11 R 12 and R 13 Each is independently a hydrocarbon group containing an ether bond and having 1 or more but less than 10 carbon atoms.

[0240] The hydrocarbon group having 1 or more but less than 10 carbon atoms can be an aliphatic hydrocarbon group with 1 or more but less than 10 carbon atoms in a monovalent state, or an aromatic hydrocarbon group with 6 or more but less than 10 carbon atoms in a monovalent state. Preferably, the aliphatic hydrocarbon group having 1 or more but less than 10 carbon atoms in a chain alkyl group or a cyclic alkyl group having 3 or more but less than 10 carbon atoms in a chain alkyl group. When the chain alkyl group has 1 or more but less than 10 carbon atoms in a chain alkyl group, it can contain an aromatic hydrocarbon group as a part of the alkyl group. The chain alkyl group having 1 or more but less than 10 carbon atoms in a chain can be straight-chain or branched.

[0241] Preferred amine compounds include, for example, N,N-dimethylethylamine, N,N-dimethylpropylamine, N,N-dimethylisopropylamine, N,N-dimethylbutylamine, N,N-dimethylisobutylamine, N,N-dimethyloctylamine, N,N-dimethyl-2-ethylhexylamine, N,N-dimethyllaurylamine, N,N-diethylmethylamine, N,N-diethylbutylamine, N,N-diethylhexylamine, N,N-diethyloctylamine, N,N-diethyl-2-ethylhexylamine, N,N-diethyllaurylamine, N,N-diisopropylmethylamine, N,N-diisopropylethylamine, N,N-diisopropylbutylamine, N,N-diisopropyl-2-ethylhexylamine, N-methyl-dioctylamine, N,N-dimethylallylamine, N-methyldiallylamine, trimethylpropylamine, etc. N,N-diethylpropylamine, tripropylamine, tributylamine, N,N-dibutylpropylamine, N,N-dipropyloctylamine, N,N-dimethylbenzylamine, N,N-diethylbenzylamine, N,N-dibenzylmethylamine, tribenzylamine, N,N-dimethyl-4-methylbenzylamine, N,N-dimethylcyclohexylamine, N,N-diethylcyclohexylamine, N,N-dicyclohexylmethylamine The preferred amine compounds include N,N-dicyclohexylethylamine, tricyclohexylamine, N-methylpyrrolidine, N-ethylpyrrolidine, N-propylpyrrolidine, N-butylpyrrolidine, N-methylpiperidine, N-ethylpiperidine, N-propylpiperidine, N-butylpiperidine, N-methylmorpholine, N-ethylmorpholine, N-propylmorpholine, N-butylmorpholine, N-sec-butylmorpholine, N-tert-butylmorpholine, N-isobutylmorpholine, and quinine rings. It should be noted that these compounds are only a subset of the preferred amine compounds, and the preferred amine compounds are not limited to these. Furthermore, one or more of these amine compounds may be used.

[0242] Preferably, N,N-dimethylpropylamine, N,N-dimethylbutylamine, N,N-dimethyl-2-ethylhexylamine, N,N-diethylmethylamine, N,N-diisopropylethylamine, N,N-diisopropyl-2-ethylhexylamine, N,N-dimethylallylamine, tripropylamine, tributylamine, N,N-diethylpropylamine, N,N-dibutylpropylamine, N,N-dipropyloctylamine, N,N-dimethylcyclohexylamine, N,N-dicyclohexylmethylamine, N-methylpyrrolidine, N-methylpiperidine, N-ethylpiperidine, N-methylmorpholine, N-ethylmorpholine, or N-isobutylmorpholine.

[0243] Furthermore, N,N-dimethylpropylamine, N,N-dimethylbutylamine, N,N-diethylmethylamine, N,N-diisopropylethylamine, tripropylamine, tributylamine, N,N-dipropyloctylamine, N,N-dimethylcyclohexylamine, or N-methylpiperidine are preferred, and N,N-dimethylpropylamine, N,N-dimethylbutylamine, N,N-diethylmethylamine, N,N-diisopropylethylamine, tripropylamine, tributylamine, or N,N-dipropyloctylamine are most preferred.

[0244] [Other amine compounds]

[0245] In addition to containing the tertiary ammonium cations of the aforementioned amine compounds, the polyisocyanate component (A) may also contain tertiary ammonium cations of other amine compounds.

[0246] The term "other amine compound" can refer to any amine compound other than those mentioned above, without particular limitation. Examples of other amine compounds include, for instance, the compounds shown in (a) to (b) below. Furthermore, one or more of these other amine compounds may be used.

[0247] (a) Examples include trimethylamine, N,N-dimethylpentylamine, N,N-dimethylhexylamine, N,N-diethylisopropylamine, N,N-diethylisobutylamine, N,N-dimethylheptylamine, N,N-dimethylnonylamine, N,N-dimethyldecylamine, N,N-dimethylundecylamine, N,N-dimethyldodecylamine, N,N-dimethyltridecylamine, N,N-dimethylstearylamine, N,N-diethylpentylamine, N,N-diethylheptylamine, N,N-diethylnonylamine, N,N-diethyldecylamine, N,N-diethylundecylamine, N,N-diethyldodecylamine, and N,N-diethyldodecylamine. Alkylamines, N,N-diethyltridecylamine, N,N-diethylstearylamine, N,N-dibutylmethylamine, N,N-dibutylethylamine, N,N-dibutylpentylamine, N,N-dibutylhexylamine, N,N-dibutylheptylamine, N,N-dibutyloctylamine, N,N-dibutyl-2-ethylhexylamine, N,N-dibutylnonylamine, N,N-dibutyldecylamine, N,N-dibutylundecylamine, N,N-dibutyldodecylamine, N,N-dibutyltridecylamine, N,N-dibutylstearylamine, tripentylamine, trihexylamine, and other tertiary amines with chain-like aliphatic hydrocarbon groups.

[0248] (b) Examples of tertiary amines with aromatic hydrocarbon groups include N,N-dimethylphenylamine, N,N-diethylphenylamine, and N,N-diphenylmethylamine.

[0249] [Method for manufacturing amine salts of sulfonic acids]

[0250] In the case where the above-mentioned sulfonic acid forms a salt with the above-mentioned amine compound, that is, in the case of an amine salt of sulfonic acid, it can be obtained, for example, by mixing a sulfonic acid having a hydroxyl group and an amine compound to carry out a neutralization reaction.

[0251] The neutralization reaction can be carried out before reacting with the polyisocyanate. Alternatively, it can be carried out simultaneously with the reaction with the polyisocyanate. Alternatively, it can be carried out by adding an amine compound after reacting the polyisocyanate with a sulfonic acid having a hydroxyl group.

[0252] The neutralization reaction is preferably carried out before reacting with the polyisocyanate.

[0253] Regarding the mixing ratio of the hydroxyl-containing sulfonic acid to the amine compound in the neutralization reaction, the molar ratio of the hydroxyl-containing sulfonic acid to the amine compound is preferably 0.5 or more and 2 or less, more preferably 0.8 or more and 1.5 or less.

[0254] When the neutralization reaction is carried out in advance, the temperature and time can be appropriately determined according to the progress of the reaction. The temperature is usually preferably above 0°C and below 100°C, and the mixing time is preferably above 10 minutes and below 24 hours.

[0255] The solvent used in preparing the amine salts of the sulfonic acids containing hydroxyl groups is preferably water or a hydrophilic solvent. There are no particular limitations on the hydrophilic solvent; examples include alcohols, ether alcohols, ketones, and amide solvents. These solvents can be used alone or in combination.

[0256] Examples of alcohols include methanol, ethanol, propanol, butanol, and isopropanol.

[0257] Examples of ether alcohols include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and dipropylene glycol monomethyl ether.

[0258] Examples of ketones include acetone, methyl ethyl ketone, and methyl isobutyl ketone.

[0259] Examples of amide solvents include N,N-dimethylformamide and N,N-dimethylacetamide.

[0260] After the neutralization reaction, it is preferable to remove water or a hydrophilic solvent.

[0261] [Characteristics of polyisocyanate component (A)]

[0262] In the polyisocyanate component (A), from the viewpoint of emulsification and coating properties, relative to 100 moles of isocyanate groups in the polyisocyanate of the raw material, it is preferable to modify the isocyanate groups with a sulfonic acid having hydroxyl groups at a ratio of 0.25 moles or more and 50 moles or less, more preferably at a ratio of 0.5 moles or more and 20 moles or less, and even more preferably at a ratio of 1 mole or more and 10 moles or less.

[0263] Furthermore, when the non-volatile component is set to 100% by mass, from the viewpoint of solvent resistance of the coating film, the isocyanate group content of the polyisocyanate component (A) is preferably 10% by mass or more and 25% by mass or less, more preferably 15% by mass or more and 24% by mass or less. There are no particular limitations on the method for controlling the isocyanate group content within the above range; for example, methods such as adjusting the ratio of sulfonic acid to polyisocyanate can be cited.

[0264] Furthermore, from the viewpoint of solvent resistance of the coating film, the number average molecular weight of the polyisocyanate used in the polyisocyanate component (A), including polyisocyanates containing sulfonate anionic groups and unreacted polyisocyanates, is preferably 450 or more and 2,000 or less, more preferably 500 or more and 1,800 or less, and even more preferably 550 or more and 1,550 or less. As a method for controlling the number average molecular weight within the above range, there are no particular limitations; examples include adjusting the ratio of sulfonic acid and amine compounds to polyisocyanates.

[0265] Number-average molecular weight can be determined, for example, using gel permeation chromatography (GPC).

[0266] Furthermore, from the viewpoints of solvent resistance of the coating film and isocyanate group retention, the average number of functional groups of the polyisocyanate (including modified polyisocyanate and unreacted polyisocyanate) used in the polyisocyanate component (A) is preferably 1.8 or more and 6.2 or less, more preferably 2.0 or more and 5.6 or less, and even more preferably 2.5 or more and 4.6 or less. As a method for controlling the average number of functional groups within the above range, there are no particular limitations; examples include adjusting the ratio of sulfonic acid and amine compound to polyisocyanate.

[0267] It should be noted that the isocyanate group content, non-volatile components, and average number of functional groups can be determined using the methods described in the examples below.

[0268] (Other ingredients)

[0269] The polyisocyanate component (A) is a composition comprising the above-mentioned polyisocyanate containing an intramolecular sulfonate anion group, unreacted polyisocyanate, and amine compound (1) as a tertiary ammonium cation. The substrate coating composition of this embodiment may also contain other components besides the above-mentioned polyisocyanate containing an intramolecular sulfonate anion group, unreacted polyisocyanate, and amine compound (1) as a tertiary ammonium cation.

[0270] Other components are not specifically limited and can include, for example, solvents, antioxidants, light stabilizers, polymerization inhibitors, and surfactants.

[0271] The solvent used in the polyisocyanate component (A) can be either a hydrophilic solvent or a hydrophobic solvent. These solvents can be used alone or in combination.

[0272] As a hydrophobic solvent, there are no particular limitations, but examples include mineral oil, solvent naphtha, LAWS (Low Aromatic White Spirit), HAWS (High Aromatic White Spirit), toluene, xylene, cyclohexane, esters, ketones, and amides.

[0273] Examples of esters include ethyl acetate and butyl acetate.

[0274] Examples of ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.

[0275] Examples of amides include N,N-dimethylformamide and N,N-dimethylacetamide.

[0276] As a hydrophilic solvent, there are no particular limitations; examples include alcohols, ethers, and esters of ether alcohols.

[0277] Examples of alcohols include methanol, ethanol, propanol, isopropanol, and 2-ethylhexanol.

[0278] Examples of ethers include diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, and dipropylene glycol dimethyl ether.

[0279] Examples of esters that are ether alcohols include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate.

[0280] In the polyisocyanate component (A), the solvent content is preferably 0% by mass or more and 90% by mass or less relative to the total mass of the coating composition for the substrate, more preferably 0% by mass or more and 50% by mass or less, and even more preferably 0% by mass or more and 30% by mass or less.

[0281] Furthermore, from the perspective of protecting the Earth's environment, the solvent content in the polyisocyanate component (A) is preferably 0% by mass.

[0282] Examples of antioxidants and light stabilizers include substances shown in (a) to (e) below. These may be contained individually or in two or more forms.

[0283] (a) Aliphatic, aromatic or alkyl-substituted aromatic esters of phosphoric acid or phosphorous acid, and hypophosphoric acid derivatives.

[0284] (b) Phosphorus compounds such as phenylphosphonic acid, phenylphosphonic acid, diphenylphosphonic acid, polyphosphonate, dialkyl pentaerythritol diphosphite, and dialkyl bisphenol A diphosphite.

[0285] (c) Phenolic derivatives (especially hindered phenolic compounds).

[0286] (d) Sulfur-containing compounds such as thioether compounds, dithioester compounds, mercaptobenzimidazole compounds, diphenylthiourea compounds, and thiodipropionates.

[0287] (e) Tin compounds such as tin maleate and dibutyltin monooxide.

[0288] Examples of polymerization inhibitors include hydroquinones, phenols, cresols, catechols, and benzoquinones. More specifically, examples include benzoquinone, p-benzoquinone, p-toluenequinone, p-dimethylquinone, naphthoquinone, 2,6-dichloroquinone, hydroquinone, trimethylhydroquinone, catechol, p-tert-butylcatechol, 2,5-di-tert-butylhydroquinone, monomethylhydroquinone, p-methoxyphenol, 2,6-di-tert-butyl-p-cresol, and hydroquinone monomethyl ether. These can be contained individually or in combination with two or more compounds.

[0289] Examples of surfactants include well-known anionic surfactants, cationic surfactants, and amphoteric surfactants.

[0290] In the polyisocyanate component (A), the total content of antioxidant, light stabilizer, polymerization inhibitor and surfactant is preferably 0% by mass or more and 10% by mass or less relative to the total mass of the coating composition for the substrate, more preferably 0% by mass or more and 5% by mass or less, and even more preferably 0% by mass or more and 2% by mass or less.

[0291] Method for manufacturing polyisocyanate component (A)

[0292] The method for manufacturing the substrate coating composition of this embodiment preferably includes, for example, the steps shown in (1) or (2) below.

[0293] (1) The process of mixing and reacting an amine salt of a sulfonic acid with an active hydrogen group and a polyisocyanate.

[0294] (2) The process of mixing and reacting sulfonic acid, polyisocyanate and the above-mentioned amine compound with active hydrogen groups.

[0295] In step (1), the amine salt of sulfonic acid is preferably added to the polyisocyanate after pre-preparation.

[0296] In addition, in step (2), sulfonic acid and amine compounds with active hydrogen groups can be added to the polyisocyanate at the same time, or they can be added sequentially.

[0297] In the preferred step (1), the amine salt of sulfonic acid is more preferably added to the polyisocyanate after pre-preparation.

[0298] In this reaction process, from the viewpoint of emulsification and coating properties, the mixing ratio of the sulfonic acid or its amine salt with active hydrogen groups to the polyisocyanate is preferably in the range of 2 or more and 400 or less, more preferably in the range of 5 or more and 200 or less, and even more preferably in the range of 10 or more and 100 or less, based on the molar ratio of isocyanate groups to hydroxyl groups.

[0299] In this reaction process, the reaction temperature and reaction time can be appropriately determined according to the progress of the reaction. The reaction temperature is preferably above 0°C and below 150°C, and the reaction time is preferably above 30 minutes and below 48 hours.

[0300] In addition, known and commonly used catalysts may be used in this reaction process, depending on the circumstances. There are no particular limitations on the catalyst; examples include those shown in (a) to (f) below. These can be used alone or in combination.

[0301] (a) Organotin compounds such as tin octanoate, tin 2-ethyl-1-hexanoate, tin ethylhexanoate, tin laurate, tin palmitate, dibutyltin oxide, dibutyltin dichloride, dibutyltin diacetate, dibutyltin dimaleate, dibutyltin dilaurate, and dioctyltin dilaurate.

[0302] (b) Organic zinc compounds such as zinc chloride, zinc octanoate, zinc 2-ethyl-1-hexanoate, zinc 2-ethylhexanoate, zinc stearate, zinc naphthenate, and zinc acetylacetonate.

[0303] (c) Organotitanium compounds.

[0304] (d) Organozirconium compounds.

[0305] (e) Tertiary amines such as triethylamine, tributylamine, N,N-diisopropylethylamine, and N,N-dimethylethanolamine.

[0306] (f) Diamines such as triethylenediamine, tetramethylethylenediamine, and 1,4-diazabicyclo[2.2.2]octane.

[0307] In the manufacturing method of polyisocyanate component (A), a solvent may or may not be used. The solvent used in the manufacturing method of polyisocyanate component (A) may be a hydrophilic solvent or a hydrophobic solvent. As hydrophilic and hydrophobic solvents, the same solvents exemplified in the other components above can be listed.

[0308] In addition, in the method for manufacturing polyisocyanate component (A), besides sulfonic acids having hydroxyl groups, polyisocyanates, and amine compounds, at least one selected from the group consisting of antioxidants, light stabilizers, polymerization inhibitors, and surfactants may be added. Examples of antioxidants, light stabilizers, polymerization inhibitors, and surfactants are the same as those exemplified in the other components described above.

[0309] The manufacturing methods for the above-mentioned polyisocyanate components containing reaction products with alcohols can be listed as follows (4) to (6).

[0310] (4) A method for reacting a polyisocyanate with an alcohol, an amine salt of a sulfonic acid with an active hydrogen group (or a sulfonic acid with an active hydrogen group and the above-mentioned amine compound) in a single step.

[0311] (5) A method of reacting polyisocyanates with alcohols, amine salts of sulfonic acids with active hydrogen groups (or sulfonic acids with active hydrogen groups and the above-mentioned amine compounds), and then mixing them with other polyisocyanates.

[0312] (6) A method for separately preparing the reaction product (E) of polyisocyanate and alcohol and the amine salt of polyisocyanate and sulfonic acid with active hydrogen group (or sulfonic acid with active hydrogen group and the above amine compound) (F), and mixing (E) and (F) in a desired mass ratio.

[0313] Of the methods (4) to (6) above, from the viewpoint of shortening the manufacturing process and manufacturing time and obtaining a substrate coating composition with stable physical properties, method (4) or (5) is preferred, and from the viewpoint of suppressing dilution turbidity and alkali resistance, method (5) is further preferred.

[0314] Furthermore, the reaction of amine salts of sulfonic acids with active hydrogen groups with polyisocyanates and alcohols is less likely to produce dilution turbidity and low-temperature turbidity, and is therefore preferred.

[0315] The reaction of polyisocyanates with alcohols, sulfonic acids containing active hydrogen groups, or their amine salts can be catalyzed using organometallic salts, tertiary amine compounds, or alkali metal alkoxides. Examples of metals constituting the aforementioned organometallic salts include tin, zinc, and lead. Examples of alkali metals include sodium.

[0316] The reaction temperature of polyisocyanates with alcohols, sulfonic acids containing active hydrogen groups, or their amine salts is preferably -20°C or higher and 150°C or lower, more preferably 30°C or higher and 130°C or lower. By setting the reaction temperature above the aforementioned lower limit, there is a tendency to further increase reactivity. Furthermore, by setting the reaction temperature below the aforementioned upper limit, there is a tendency to more effectively suppress side reactions.

[0317] The preferred alcohol reacts completely with the polyisocyanate, including a sulfonic acid or its amine salt containing an active hydrogen group, without leaving any residue in an unreacted state. By not leaving any residue in an unreacted state, the water dispersibility of the polyisocyanate component (A) and the pot life of the coating composition for the substrate tend to improve.

[0318] When the polyisocyanate component (A) is a sulfonic acid having hydroxyl groups, the manufacturing method of the polyisocyanate component (A) preferably includes the steps of (1) or (2) above.

[0319] In the preferred step (1), the amine salt of sulfonic acid is more preferably added to the polyisocyanate after pre-preparation.

[0320] Hydroxyl Resin Ingredients

[0321] The hydroxyl-containing resin component in the base coating composition of this embodiment is not particularly limited, and examples include acrylic resins, polyester resins, polyether resins, epoxy resins, fluororesins, polyurethane resins, polyvinylidene chloride copolymers, polyvinyl chloride copolymers, vinyl acetate copolymers, acrylonitrile butadiene copolymers, polybutadiene copolymers, styrene butadiene copolymers, etc.

[0322] Among them, acrylic resins, polyurethane resins, or polyester resins are preferred as resins.

[0323] Examples of acrylic resins include: water-soluble acrylic resins with a weight-average molecular weight of 5,000 to 100,000, preferably 10,000 to 90,000, and more preferably 20,000 to 80,000, obtained by copolymerizing a mixture of monomers containing hydrophilic groups such as hydroxyl-containing polymeric unsaturated monomers and carboxyl-containing polymeric unsaturated monomers; and acrylic resin emulsions with a weight-average molecular weight of 50,000 or more, preferably 75,000 or more, and more preferably 100,000 or more.

[0324] Examples of hydroxyl-containing polymerizable unsaturated monomers include hydroxyalkyl esters of acrylic acid or methacrylic acid such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, and 4-hydroxybutyl methacrylate; polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, etc. These can be used individually or in combination of two or more.

[0325] Examples of carboxyl-containing polymerizable unsaturated monomers include (meth)acrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, and monoalkyl half-esters of their dicarboxylic acids. Examples of other polymerizable unsaturated monomers containing hydrophilic groups include polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, and other polymerizable unsaturated monomers containing polyalkylene chains.

[0326] Other polymerizable unsaturated monomers mentioned above include, for example, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate, isobornyl methacrylate, etc., which are alkyl or cycloalkyl esters of (meth)acrylic acid with 1 to 24 carbon atoms; 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, or 3-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, etc., which are hydroxyalkyl esters of (meth)acrylic acid; glycidyl methacrylate, acrylonitrile, acrylamide, styrene, vinyltoluene, vinyl acetate, vinyl chloride, 1,6-hexanediol diacrylate, etc., which can be used alone or in combination of two or more.

[0327] The copolymerization of the above-mentioned monomer mixture can be carried out by methods known in themselves. For example, if a water-soluble acrylic resin is desired, it can be carried out by solution polymerization or the like. If an acrylic resin emulsion is desired, it can be carried out by emulsion polymerization or the like.

[0328] When the acrylic resin is an acrylic resin emulsion obtained by emulsion polymerization, it can be a multi-layered granular emulsion obtained by emulsion polymerization of a monomer mixture in multiple stages in the presence of water and an emulsifier.

[0329] The carboxyl groups of acrylic resins can be neutralized using the aforementioned alkaline substances as needed.

[0330] The acrylic resins contained preferably have an acid value in the range of 10–100 mg KOH / g, further 15–80 mg KOH / g, particularly 20–60 mg KOH / g, and a hydroxyl value in the range of 10–250 mg KOH / g, further 20–200 mg KOH / g, particularly 30–150 mg KOH / g.

[0331] Polyester resins include substances obtained by neutralizing polyester resins prepared by esterification reactions using polyols and polyacids, and further, monoacids as needed, and oil components (including fatty acids). The polyester resin typically has a weight-average molecular weight in the range of about 3,000 to 100,000, preferably 4,000 to 70,000, and more preferably 5,000 to 30,000.

[0332] Examples of the aforementioned polyols include ethylene glycol, diethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, 2,2-dimethylpropanediol, glycerol, trimethylolpropane, pentaerythritol, ethylene oxide adducts of bisphenol compounds, and propylene oxide adducts. These can be used individually or in combination of two or more.

[0333] Examples of polybasic acids include phthalic acid, isophthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, maleic acid, succinic acid, adipic acid, sebacic acid, trimellitic acid, pyromellitic acid, and their anhydrides. These can be used individually or in combination of two or more. Examples of monobasic acids include benzoic acid and tert-butylbenzoic acid. Examples of oil components include castor oil, dehydrated castor oil, safflower oil, soybean oil, linseed oil, tall oil, coconut oil, and their fatty acids. These can be used individually or in combination of two or more.

[0334] In the aforementioned polyester resin, the introduction of carboxyl groups can be achieved, for example, by using polyacids such as trimellitic acid and pyromellitic acid, which have three or more carboxyl groups per molecule, as part of the polyacid component, or by performing a half-ester addition to a dicarboxylic acid. Furthermore, the introduction of hydroxyl groups can also be easily achieved, for example, by using polyols such as glycerol and trimethylolpropane, which have three or more hydroxyl groups per molecule, as part of the polyol component.

[0335] The carboxyl groups of the aforementioned polyester resin can be neutralized using an alkaline substance. Water-soluble alkaline substances are preferred, and examples include ammonia, methylamine, ethylamine, propylamine, butylamine, dimethylamine, trimethylamine, triethylamine, ethylenediamine, morpholine, methylethanolamine, dimethylethanolamine, diethanolamine, triethanolamine, diisopropanolamine, 2-amino-2-methylpropanol, etc. These can be used individually or in combination of two or more.

[0336] The polyester resin preferably has an acid value in the range of 10–100 mg KOH / g, further 20–80 mg KOH / g, particularly 20–50 mg KOH / g, and a hydroxyl value in the range of 10–300 mg KOH / g, further 30–200 mg KOH / g, particularly 50–200 mg KOH / g.

[0337] The polyurethane resin can suitably be a hydrophilic polyurethane resin that is soluble or dispersed in water, for example, particularly preferably an aqueous dispersion of a self-emulsifying urethane resin having an average particle size of about 0.001 to 1.0 μm, especially about 0.02 to 0.3 μm, from which some or all of the organic solvent used in the manufacturing process has been distilled off. This aqueous dispersion of the self-emulsifying urethane resin can be obtained by chain extension and emulsification of a urethane prepolymer obtained by reacting (i) aliphatic and / or alicyclic diisocyanates, (ii) diols with a number average molecular weight of 500 to 5000, (iii) low molecular weight polyhydroxy compounds and (iv) dihydroxymethyl alkyl acids in an NCO / OH equivalent ratio typically in the range of 1 / 0.5 to 1 / 0.95, especially 1 / 0.6 to 1 / 0.9, in one-step or multi-step reactions after or during neutralization.

[0338] Polyurethane resins preferably have an acid value in the range of 10–60 mg KOH / g, further 20–50 mg KOH / g, and especially 20–40 mg KOH / g, and a hydroxyl value in the range of 10–60 mg KOH / g, further 20–50 mg KOH / g, and especially 20–40 mg KOH / g.

[0339] Examples of polyether resins mentioned above include those obtained by any of the methods described in (1) to (3) below.

[0340] (1) Polyether polyols or polytetramethylene glycols obtained by adding polyols alone or in mixtures to epoxides alone or in mixtures.

[0341] (2) Polyether polyols obtained by reacting polyfunctional compounds with epoxides.

[0342] (3) Polymer polyols obtained by polymerizing acrylamide and the like using polyether polyols obtained in (1) or (2) as a medium.

[0343] Examples of such polyols include glycerol and propylene glycol.

[0344] Examples of the aforementioned epoxides include ethylene oxide and propylene oxide.

[0345] Examples of such multifunctional compounds include ethylenediamine and ethanolamines.

[0346] Examples of epoxy resins mentioned above include phenolic varnish-type epoxy resins, β-methylepimercohydrin-type epoxy resins, cyclic ethylene oxide-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, amino-glycidyl-type epoxy resins, halogenated epoxy resins, resorcinol-type epoxy resins, and resins obtained by modifying these epoxy resins with amino compounds, polyamide compounds, etc.

[0347] Examples of the aforementioned fluorinated resins include copolymers of fluoroolefins, cyclohexyl vinyl ethers, hydroxyalkyl vinyl ethers, and monocarboxylic acid vinyl esters disclosed in references 1 (Japanese Patent Application Publication No. 57-34107) and 2 (Japanese Patent Application Publication No. 61-275311).

[0348] [Method for manufacturing coating compositions for substrates]

[0349] The substrate coating composition of the present invention can be obtained by mixing the above-mentioned polyisocyanate component (A) and the above-mentioned hydroxyl-containing resin component with various additive components used as needed by a known method.

[0350] For example, various additives are added as needed to the hydroxyl-containing resin component or its aqueous dispersion or solution. Next, the aforementioned polyisocyanate component (A) or its aqueous dispersion is added as a curing agent, and water and solvent are further added as needed to adjust the viscosity. Then, forced stirring is performed using a stirring device, thereby obtaining a coating composition for a substrate.

[0351] (NCO / OH ratio)

[0352] From the viewpoint of low-temperature curing properties, the isocyanate group in the polyisocyanate component is contained in a ratio of 1.1 to 2.0 equivalents relative to 1 equivalent of hydroxyl groups in the hydroxyl-containing resin component, more preferably in a ratio of 1.3 to 2.0 equivalents, and most preferably in a ratio of 1.5 to 1.9 equivalents.

[0353] (Other ingredients)

[0354] The base coating composition of the present invention may contain, as needed, appropriate additives for coatings such as coloring pigments, extender pigments, and polyisocyanates such as melamine resins (e.g., all-alkyl, hydroxymethyl alkyl, imino alkyl, etc.), curing agents, curing catalysts, thickeners, ultraviolet absorbers, light stabilizers, defoamers, plasticizers, organic solvents, surface conditioners, and anti-settling agents.

[0355] The substrate coating composition of the present invention can be applied to the substrate by methods known per se, such as air spraying, airless spraying, rotary atomization coating, curtain coating, etc., and electrostatics can also be applied during coating. Among these, air spraying and rotary atomization coating are preferred. The coating amount is preferably 10 to 50 μm, preferably 10 to 40 μm, in terms of cured film thickness.

[0356] <Multilayer Coating Laminate>

[0357] One example of the multilayer coating laminate in this embodiment is a multilayer coating laminate formed by sequentially stacking a first coating and a second coating.

[0358] One example of the multilayer coating laminate in this embodiment is a multilayer coating laminate formed by sequentially stacking a first coating, a second coating, and a third coating.

[0359] In the multilayer coating laminate of this embodiment, the first coating is formed from the substrate coating composition described above. The second coating is formed from a coating composition containing a hydroxyl-containing resin component. The third coating is formed from a two-component coating composition containing a hydroxyl-containing resin component and a polyisocyanate component.

[0360] The method for forming a multilayer coating laminate according to this embodiment preferably includes the following steps: applying the above-mentioned substrate coating composition as a first coating composition onto a workpiece to obtain a first coating film; and stacking one or more coating films on the obtained first coating film.

[0361] The composition of the first coating composition (i.e., the coating composition for the substrate described above) and the composition for forming the second coating film may be the same or different. In this embodiment, from the viewpoint of improving the color tone of the multilayer coating laminate, the composition of the first coating composition (i.e., the coating composition for the substrate described above) and the composition for forming the second coating film are preferably different.

[0362] The method for forming a multilayer coating laminate according to this embodiment preferably includes the following steps: applying the above-mentioned substrate coating composition as a first coating composition onto a workpiece to obtain a first coating film; applying a second coating composition onto the obtained first coating film to obtain a second coating film; and applying a third coating composition onto the obtained second coating film to obtain a third coating film.

[0363] One embodiment of the method for forming a multilayer coating laminate includes the following steps: applying the above-mentioned substrate coating composition as a first coating composition to a workpiece to obtain a first uncured coating film; applying a second coating composition to the obtained first uncured coating film to obtain a second uncured coating film; and applying a third coating composition to the obtained second uncured coating film to obtain a third uncured coating film.

[0364] One embodiment of the method for forming a multilayer coating laminate includes the following steps: simultaneously curing a first uncured coating, a second uncured coating, and a third uncured coating by heating at a temperature of 40°C or higher and 140°C or lower, thereby forming a multilayer coating laminate comprising the three layers of the first coating, the second coating, and the third coating.

[0365] By using the above-mentioned substrate coating composition as the first coating composition, even when cured at a low temperature of 40°C or higher and 140°C or lower, it is possible to manufacture a multilayer coating laminate with excellent hardness, water resistance and crack resistance.

[0366] When a third uncured coating is laminated onto the first and second uncured coatings, a portion of the components in the third coating composition migrates into the first and second uncured coatings. The polyisocyanate component migrates while forming a concentration gradient from the third uncured coating side to the substrate side within the first and second uncured coatings. Therefore, the interfilm adhesion between the first, second, and third uncured coatings is improved.

[0367] Furthermore, when the substrate is an uncured coating, the first and second coating compositions migrate into the uncured coating, forming a pre-coating layer on the surface of the substrate. The hydroxyl-containing resin component is also present in the pre-coating layer. Therefore, with the aid of the pre-coating layer, the first and second uncured coatings cure in a state of further adhesion to the substrate. Furthermore, it is preferable that the pre-coating layer also contains a polyisocyanate component that migrates from the third uncured coating via the first and second uncured coatings. By curing the pre-coating layer, the first uncured coating, the second uncured coating, and the third uncured coating all at once in the presence of the polyisocyanate component, the adhesion of the coating can be further improved.

[0368] Here, the substrate for the uncured coating preferably contains a polyol as the main agent and a melamine-based curing agent. Examples of melamine-based curing agents include those described in the "Melamine-based Curing Agents" section below.

[0369] As a method for forming the first uncured coating film, the second uncured coating film, and the third uncured coating film, the first coating composition, the second coating composition, and the third coating composition are respectively laminated onto a substrate, a coating film, or other object to be coated using methods such as roller coating, curtain flow coating, spraying, bell coating, or electrostatic coating, thereby forming the coating film.

[0370] In the forming method of this embodiment, the lower limit of the heating temperature for simultaneously curing the first, second, and third uncured coatings after obtaining the third uncured coating is preferably 40°C, more preferably 60°C, and most preferably 80°C. Furthermore, the upper limit of the heating temperature is preferably 140°C, more preferably 120°C.

[0371] The lower limit of the heating time is preferably 10 minutes, more preferably 15 minutes. In addition, the upper limit of the heating time is preferably 40 minutes, more preferably 35 minutes.

[0372] By setting the heating temperature and heating time to the range described above, the curing properties and yellowing resistance of the multilayer coating are improved.

[0373] In the formation method of this embodiment, a short preheating period can be performed after obtaining the first uncured coating and the second uncured coating, or before applying the first uncured coating and the second uncured coating to the uncured coating as a substrate. The preheating is a low-temperature short-time drying process at approximately 70°C to 80°C for approximately 1 minute to 5 minutes, and the first uncured coating and the second uncured coating can be formed under conditions where curing is not required.

[0374] In one embodiment of the method for forming a multilayer coating laminate, the first coating composition, the second coating composition, and the third coating composition are preferably different from each other.

[0375] The first coating, the second coating, and the third coating may each consist of only one layer, or may consist of multiple layers of two or more layers.

[0376] Alternatively, the third coating may be, for example, a polyurethane resin coating.

[0377] The lower limit of the cured film thickness of the first, second, and third coatings is preferably 10 μm, more preferably 15 μm. On the other hand, the upper limit of the cured film thickness is preferably 60 μm, more preferably 50 μm. By keeping the cured film thickness within the above range, the durability of the multilayer coating laminate can be further improved.

[0378] (Second coating composition and third coating composition)

[0379] The second coating composition is, for example, a coating composition containing a hydroxyl-containing resin component. The hydroxyl-containing resin component of the second coating composition may be the aforementioned hydroxyl-containing resin component.

[0380] The second coating composition may further comprise a polyisocyanate component (C). The polyisocyanate component (C) may, for example, be the polyisocyanate component (A) described above or the polyisocyanate component (B) described later.

[0381] The second coating composition preferably further comprises a capped polyisocyanate component (D).

[0382] The capped polyisocyanate component (D) is obtained, for example, by reacting the polyisocyanate component (C) with a capping agent.

[0383] By including a capped polyisocyanate component (D) in the second coating composition, the migration of curing agents and the like from the first coating composition to the second coating composition becomes difficult, and the orientation of the pigments contained in the second coating composition is less likely to be disordered, thus resulting in a better final appearance of the multilayer coating film.

[0384] The polyisocyanate component used in the capped polyisocyanate component (D) is preferably a substance derived from a diisocyanate and a polyol with an average functional group number of 3.0 or more and 8.0 or less. This allows for an increase in the average isocyanate group number of the polyisocyanate. In this polyisocyanate, urethane groups are formed through the reaction of the hydroxyl groups of the polyol with the isocyanate groups of the diisocyanate monomer.

[0385] From the viewpoint of improving the low-temperature curability when forming a resin film, the average number of isocyanate functional groups of the polyisocyanate is preferably 2 or more. From the viewpoint of balancing the low-temperature curability and compatibility when forming a resin film, the average number of isocyanate functional groups of the polyisocyanate is more preferably 3 or more and 20 or less, further preferably 3.2 or more and 10 or less, particularly preferably 3.5 or more and 8 or less, and most preferably 4.2 or more and 6 or less.

[0386] The average number of functional groups of the polyol used in the capped polyisocyanate component (D) 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. It should be noted that the average number of functional groups of the polyol referred to herein is the number of hydroxyl groups present in one molecule of polyol.

[0387] From the viewpoint of improving the hardness and strength of the coating film, the number average molecular weight of the polyol used in the end-capped polyisocyanate component is preferably 100 or more and 1000 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.

[0388] By ensuring that the number-average molecular weight of the polyol is within the aforementioned range, the low-temperature curability of the resin film made from the end-capped polyisocyanate component (D) is superior, and particularly its hardness and strength are also superior. The number-average molecular weight Mn of the polyol is, for example, the number-average molecular weight of polystyrene as determined by GPC.

[0389] Examples of such polyols include polycaprolactone polyols derived from trimethylolpropane, glycerol, polyols with three or more elements, and ε-caprolactone.

[0390] Commercially available polycaprolactone polyols include, for example, Daicel'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).

[0391] The capping agent used in the capped polyisocyanate component (D) is not particularly limited, but specifically, compounds having one active hydrogen atom in the molecule can be listed.

[0392] Examples of such end-capping agents include alcohol compounds, alkylphenol compounds, phenol compounds, active methylene compounds, thiol compounds, acid amide compounds, acid imide compounds, imidazole compounds, urea compounds, oxime compounds, amine compounds, imine compounds, pyrazole compounds, and triazole compounds. These end-capping agents can be used alone or in combination of two or more.

[0393] From the viewpoint of achieving good low-temperature curing properties, active methylene compounds, imidazole compounds, or pyrazole compounds are preferred, with active methylene compounds being even more preferred.

[0394] As an active methylene compound, it preferably comprises a malonate having a secondary alkyl group or a malonate having a primary alkyl group and a malonate having a tertiary alkyl group, more preferably comprising a malonate having a secondary alkyl group and a malonate having a tertiary alkyl group. The capping agent may comprise one type each of a malonate having a secondary alkyl group, a malonate having a primary alkyl group and a malonate having a tertiary alkyl group, or may comprise two or more types in combination.

[0395] There are no particular limitations on the malonic esters containing primary alkyl groups, and examples include dimethyl malonate, diethyl malonate, dipropyl malonate, dibutyl malonate, dicyclohexyl malonate, and diphenyl malonate. Among these, diethyl malonate is preferred as a malonic ester containing primary alkyl groups.

[0396] There are no particular limitations on the malonate having a secondary alkyl group, and examples include di-sec-butyl malonate, diisopropyl malonate, and isopropyl ethyl malonate. Among these, diisopropyl malonate is preferred as the malonate having a secondary alkyl group.

[0397] As a malonic acid ester containing a tert-alkyl group, there is no particular limitation, and examples include di-tert-butyl malonate, di(2-methyl-2-butyl) malonate, di(2-methyl-2-pentyl) malonate, ethyl (tert-butyl) malonate, ethyl (2-methyl-2-butyl) malonate, isopropyl (2-methyl-2-butyl) malonate, ethyl (2-methyl-2-pentyl) malonate, isopropyl (2-methyl-2-pentyl) malonate, and hexyl isopropyl (2-methyl-2-pentyl) malonate. Among them, di(2-methyl-2-butyl) malonate, di(2-methyl-2-pentyl) malonate, isopropyl (2-methyl-2-butyl) malonate, ethyl (2-methyl-2-pentyl) malonate, and isopropyl (2-methyl-2-pentyl) malonate are preferred, as are ethyl (2-methyl-2-butyl) malonate, isopropyl (2-methyl-2-butyl) malonate, ethyl (2-methyl-2-pentyl) malonate, and hexyl isopropyl (2-methyl-2-pentyl) malonate, or di-tert-butyl malonate, isopropyl (2-methyl-2-butyl) malonate, or isopropyl (2-methyl-2-pentyl) malonate.

[0398] Malonates containing tert-alkyl groups can be commercially available or synthesized using the method described in Reference 1 (Japanese Patent Application Publication No. 11-130728).

[0399] Regarding the capping agent used in the capped polyisocyanate component (D), in addition to malonic esters having primary alkyl groups, malonic esters having secondary alkyl groups, and malonic esters having tertiary alkyl groups, other capping agents may be further included within the range that does not inhibit the storage stability when the resin composition is made and the low-temperature curing properties when the resin film is made.

[0400] The capped polyisocyanate component (D) preferably comprises the structural unit shown in general formula (I). Hereinafter, the structural unit shown in general formula (I) is sometimes referred to as "structural unit (I)".

[0401] It can be inferred that by including "structural unit (I)", the low-temperature curing property of the second coating composition is improved, the curing agent is less likely to migrate from the first coating composition to the second coating composition, the orientation of the pigments contained in the second coating composition is less likely to be disordered, and the final appearance of the multilayer coating film will become better.

[0402] [Structural Unit (I)]

[0403] The terminated polyisocyanate contained in the terminated polyisocyanate component (D) contains a structural unit (I) represented by the following general formula (I).

[0404]

[0405] In the above general formula (I), R 11 R 12 and R 13 Each is independently an alkyl group that optionally contains one or more substituents selected from the group consisting of hydroxyl and amino groups, R 11 R 12 and R 13 The total carbon number is 4 or more and less than 20, R 14 R 15 and R 16 Each is an alkyl group that is independently composed of a hydrogen atom or optionally contains one or more substituents selected from the group consisting of hydroxyl and amino groups. The wavy line indicates the bonding site of the residue formed by removing the isocyanate group from the polyisocyanate.

[0406] As R 11 R 12 R 13 R 14 R 15 and R 16 The alkyl group in the alkyl group preferably has 1 or more and 20 or less carbon atoms, more preferably 1 or more and 8 or less carbon atoms, even more preferably 1 or more and 6 or less carbon atoms, and particularly preferably 1 or more and 4 or less carbon atoms.

[0407] Examples of alkyl groups without substituents include methyl, ethyl, propyl, isopropyl, n-butyl, tert-butyl, sec-butyl, isobutyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, 1-methylbutyl, n-hexyl, 2-methylpentyl, 3-methylpentyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, n-heptyl, 2-methylhexyl, 3-methylhexyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 3,3-dimethylpentyl, 3-ethylpentyl, 2,2,3-trimethylbutyl, n-octyl, isooctyl, 2-ethylhexyl, nonyl, decyl, etc.

[0408] Additionally, R 11 R 12 R 13 R 14 R 15 and R 16 When the alkyl group has a substituent, the substituent is a hydroxyl or amino group.

[0409] Examples of alkyl groups containing hydroxyl groups as substituents include hydroxymethyl, hydroxyethyl, and hydroxypropyl.

[0410] Examples of alkyl groups containing an amino group as a substituent include aminomethyl, aminoethyl, aminopropyl, and aminobutyl.

[0411] Examples of alkyl groups containing hydroxyl and amino groups as substituents include hydroxyaminomethyl, hydroxyaminoethyl, and hydroxyaminopropyl.

[0412] From the perspective of further improving the storage stability when preparing coating compositions and the low-temperature curing properties when preparing resin films, R 11 R 12 and R 13 Preferably, each is an unsubstituted alkyl group having 1 or more and 4 or fewer carbon atoms, more preferably methyl or ethyl, and at least one is preferably ethyl.

[0413] 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.

[0414] By making R 11 R 12 and R 13 When the total carbon number is above the lower limit mentioned above, the water-based coating composition exhibits storage stability. Conversely, when it is below the upper limit mentioned above, low-temperature curing properties are achieved. Furthermore, from the viewpoint of improving solvent resistance when forming a coating film, R... 11 R 12 and R 13 The total number of carbon atoms is more preferably 4.

[0415] Regarding R 11 R 12 and R 13 The total number of carbons, as long as the total number of carbons is within the above range, then for R 11 R 12 and R 13 There is no limit to the number of carbon atoms in each one.

[0416] Additionally, R 14 R 15 and R 16 Each is an alkyl group that is independently composed of a hydrogen atom or optionally contains one or more substituents selected from the group consisting of hydroxyl and amino groups, preferably a non-substituted alkyl group having 1 or more carbon atoms and 4 or fewer carbon atoms.

[0417] Among them, R is preferred. 14 R 15 and R 16 At least one of them is a hydrogen atom, more preferably only one is a hydrogen atom. By making R14 R 15 and R 16 At least one of the atoms is a hydrogen atom, which can further improve the storage stability when the aqueous resin composition is prepared while maintaining low-temperature curing properties. That is, as a structural unit (I), it is more preferable to include a structural unit shown in the following general formula (I-1) (hereinafter sometimes referred to as structural unit (I-1)).

[0418]

[0419] In the above general formula (I-1), R 11 R 12 R 13 R 14 and R 15 As described in general formula (I) above. The wavy line indicates the bonding site with the residue formed by removing the isocyanate group from the polyisocyanate.

[0420] The molar ratio (structural unit (I-1) / structural unit (I)) of the above-mentioned structural unit (I) is more preferably 10 mol% or more, further 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.

[0421] [Structural Unit (II)]

[0422] The preferred capped polyisocyanate component (D) also contains a structural unit represented by the following general formula (II) (hereinafter sometimes referred to as structural unit (II)).

[0423]

[0424] In the above general formula (II), R 21 R 22 R 23 and R 24 Alkyl groups that are each independently hydrogen atoms or optionally contain one or more substituents selected from the group consisting of hydroxyl and amino groups, with wavy lines indicating the bonding sites with residues formed by removing the isocyanate group from polyisocyanates.

[0425] As R 21 R 22 R 23 and R 24 The alkyl group comprising one or more substituents selected from the group consisting of hydroxyl and amino groups can be listed as "R" above. 11 R 12 R 13 R 14 R 15 and R16 The alkyl group exemplified in the example is the same as the alkyl group in the example.

[0426] Among them, as R 21 R 22 R 23 and R 24 From the viewpoint of excellent storage stability when preparing aqueous resin compositions, it is preferable to have hydrogen atoms or alkyl groups with 1 or more but less than 4 carbon atoms that do not have substituents, more preferably hydrogen atoms, methyl, or ethyl, and from the viewpoint of excellent low-temperature curing properties, methyl or ethyl is even more preferred.

[0427] R 21 R 22 R 23 and R 24 When all are methyl groups, both ester sites of the malonate ester in structural unit (II) are isopropyl. Additionally, R... 21 and R 22 One of them is a hydrogen atom, the other is a methyl group, and R 23 and R 24 When either of the atoms is a hydrogen atom and the other is a methyl group, both ester sites of the malonate ester in structural unit (II) are ethyl groups. Of particular preference is R. 21 R 22 R 23 and R 24 The malonate, which is entirely methyl, i.e., structural unit (II), has two isopropyl groups at both ester sites.

[0428] The molar ratio (structural unit (II) / structural unit (I)) of the structural unit shown in general formula (II) to the structural unit shown in general formula (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, even more preferably 50 / 50 or more and 70 / 30 or less. By setting the above molar ratio to the lower limit or above, the storage stability when preparing the resin composition can be better, and by setting it to the upper limit or below, the low-temperature curing property when preparing the resin film can be better.

[0429] Regarding molar ratios, for example, one can utilize... 1 H-NMR and 13 C-NMR was used to determine the composition ratio of structural unit (II) to structural unit (I) in the coating composition, thereby calculating the molar ratio of structural unit (II) to structural unit (I).

[0430] By making R in structural unit (I) 11 R 12 and R 13 With a total carbon number of 4 or more and 20 or less, even when combined with water-based coating compositions, it can effectively inhibit the viscosity increase and gelation of mixtures of polyhydroxy compounds, curing agents, and water during storage, thus exhibiting good storage stability. Simultaneously, a resin film with excellent curing properties at a low temperature of around 85°C can be obtained.

[0431] Alternatively, it can be a capped polyisocyanate in which at least a portion of the isocyanate groups within the molecule of the capped polyisocyanate component (D) are capped 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, it can be a capped polyisocyanate in which at least a portion of the isocyanate groups are capped with a malonic acid ester having a secondary alkyl group, or a capped polyisocyanate in which at least a portion of the isocyanate groups are capped with a malonic acid ester having a primary alkyl group, or a mixture of capped polyisocyanates in which at least a portion of the isocyanate groups are capped with a malonic acid ester having a tertiary alkyl group.

[0432] The content of the end-capped polyisocyanate component (D) in the second coating composition is preferably 0.5% by mass or more and 20% by mass or less relative to the total mass of the second coating composition, more preferably 1% by mass or more and 10% by mass or less, and most preferably 1.5% by mass or more and 6% by mass or less. Within the above range, the water resistance and final appearance of the multilayer coating laminate are improved.

[0433] The third coating composition is, for example, a two-component coating composition comprising a hydroxyl-containing resin component and a polyisocyanate component.

[0434] The polyisocyanate component used in the third coating composition may, for example, be the polyisocyanate component (A) described above or the polyisocyanate component (B) described later.

[0435] (Polyisocyanate component (B))

[0436] The polyisocyanate component (B) is used as a curing agent for the one-time curing of the first uncured coating, the second uncured coating and the third uncured coating.

[0437] The polyisocyanate component (B) preferably comprises a polyisocyanate having an isocyanurate group derived from aliphatic diisocyanate and alicyclic diisocyanate (hereinafter sometimes referred to as "isocyanurate-type polyisocyanate").

[0438] As an aliphatic and alicyclic diisocyanate, the same diisocyanate as the diisocyanate of the above-mentioned polyisocyanate component (A) can be used.

[0439] These diisocyanates can be used alone or in combination of two or more.

[0440] Among these, HDI is preferred as the diisocyanate monomer used in the manufacture of isocyanurate-type polyisocyanates, considering its industrial availability, reactivity during polyisocyanate manufacturing, and low viscosity. Alternatively, IPDI is preferred from the viewpoints of weather resistance and industrial availability.

[0441] In the polyisocyanate component (B), the content of isocyanurate trimer of the diisocyanate monomer is not particularly limited, but is preferably 55% by mass or more and 95% by mass or less relative to the total mass of the polyisocyanate component (B), more preferably 60% by mass or more and 95% by mass or less. By setting the content of isocyanurate trimer of the diisocyanate monomer to the lower limit value or above, the viscosity of the polyisocyanate component (B) can be further reduced. On the other hand, by setting the content of isocyanurate trimer of the diisocyanate monomer to the upper limit value or below, the yield of the polyisocyanate component (B) can be further improved.

[0442] The content of isocyanurate trimer of diisocyanate monomers can be determined by gel permeation chromatography (GPC).

[0443] The polyisocyanate component (B) preferably has a urea diketone group in addition to the isocyanurate group.

[0444] Regarding the content of urea diketone dimer in the diisocyanate monomer, it is preferably 2% by mass or more and 30% by mass or less relative to the total mass of the polyisocyanate component, more preferably 4% by mass or more and 26% by mass or less, even more preferably 6% by mass or more and 23% by mass or less, and particularly preferably 8% by mass or more and 20% by mass or less.

[0445] By keeping the content of urea diketone dimer in the diisocyanate monomer within the above range, the polyisocyanate component can be easily incorporated into the first uncured coating and the second uncured coating, thereby improving the final appearance and scratch resistance of the resulting multilayer coating laminate.

[0446] The content of urea diketone dimer in diisocyanate monomers can be determined by GPC.

[0447] As a method for controlling the content of urea diketone dimer in diisocyanate monomers within the above-mentioned range, methods such as (1) or (2) below can be listed as examples.

[0448] (1) The isocyanurate reaction of HDI is carried out by deactivating the catalyst and reacting at a temperature of 140°C or higher and 160°C or lower (preferably 145°C or higher and 165°C or lower) for several hours (preferably 1 hour or higher and 3 hours or lower).

[0449] (2) A method of performing an isocyanurate esterification reaction of HDI to obtain a first polyisocyanate component, adding a tert-phosphine or other ureidodiketation catalyst to HDI, reacting at a temperature of above 20°C and below 80°C for several hours to tens of hours to obtain a second polyisocyanate component, and then mixing a portion of the second polyisocyanate component into the first polyisocyanate component.

[0450] From the viewpoint of easy access, the method described in (1) above is preferred as a method for controlling the content of urea diketone dimer within the above range.

[0451] In addition, the polyisocyanate component (B) may also have at least one of the following groups as other functional groups: iminooxadiazine dione group and ureocarbamate group.

[0452] Generally, "urea carbamate group" refers to a functional group formed by an alcohol hydroxyl group and an isocyanate group, which is the group shown in formula (IV) below.

[0453]

[0454] In addition to the functional groups mentioned above, the polyisocyanate component (B) may also contain urethane groups, urea groups, biuret groups, carbodiimide groups, etc.

[0455] Furthermore, in the polyisocyanate component (B), the lower limit of the content of the component with a number average molecular weight of 700 or less is preferably 70% by mass, more preferably 72% by mass, even more preferably 74% by mass, and particularly preferably 76% by mass relative to the total mass of the polyisocyanate component (B). On the other hand, the upper limit of the content of the component with a number average molecular weight of 700 or less is preferably 90% by mass, more preferably 86% by mass, and even more preferably 82% by mass.

[0456] That is, the content of the component with a number average molecular weight of 700 or less is preferably 70% by mass or more, more preferably 72% by mass or more and 90% by mass or less, even more preferably 74% by mass or more and 86% by mass or less, and particularly preferably 76% by mass or more and 82% by mass or less.

[0457] By ensuring that the content of components with a number average molecular weight of 700 or less is above the aforementioned lower limit, the polyisocyanate component can be easily incorporated into the first and second uncured coatings, allowing for more efficient curing of the first, second, and third uncured coatings. This results in improved final appearance and scratch resistance of the obtained multilayer coating laminate.

[0458] The content of components with a number average molecular weight below 700 can be determined by GPC.

[0459] The lower limit of the average number of isocyanate groups is preferably 2.7, more preferably 2.8. On the other hand, the upper limit of the average number of isocyanate groups is preferably 4.0, more preferably 3.5, and even more preferably 3.3.

[0460] That is, the average number of isocyanate groups is preferably 2.7 or more, more preferably 2.7 or more and 4.0 or less, even more preferably 2.7 or more and 3.5 or less, particularly preferably 2.7 or more and 3.3 or less, and most preferably 2.8 or more and 3.3 or less.

[0461] By setting the average number of isocyanate groups above the aforementioned lower limit, the crosslinking property of the polyisocyanate component can be further improved, resulting in a multilayer coating laminate with superior film hardness and chemical resistance. On the other hand, by setting the average number of isocyanate groups below the aforementioned upper limit, the polyisocyanate component can easily integrate into the first and second uncured coatings, which are the lower layers. As a result, the hardness of the resulting multilayer coating laminate comprising the first, second, and third coatings tends to be good.

[0462] The average number of isocyanate groups (Fn) in the polyisocyanate component (B) can be calculated using the following formula. It should be noted that in the formula, Mn is the number-average molecular weight of the polyisocyanate component, and the NCO content is the percentage (mass%) of isocyanate groups in the polyisocyanate component.

[0463] Fn = (Mn × NCO content × 0.01) / 42

[0464] (Manufacturing method of polyisocyanate component (B))

[0465] The method for manufacturing polyisocyanate component (B) can be the same as the method for manufacturing polyisocyanate component (A).

[0466] In order to control the content of the polyisocyanate component (B) with a number average molecular weight of 700 or less within the above-mentioned range, the lower limit of the yield is preferably 5% by mass, more preferably 10% by mass, and even more preferably 15% by mass. On the other hand, the upper limit of the yield is preferably 40% by mass, more preferably 35% by mass, and even more preferably 30% by mass.

[0467] That is, the yield is preferably 5% by mass or more and 40% by mass or less, more preferably 10% by mass or more and 35% by mass or less, and even more preferably 15% by mass or more and 30% by mass or less.

[0468] By achieving a yield above the aforementioned lower limit, productivity can be further improved. On the other hand, by achieving a yield below the aforementioned upper limit, the content of components with a number average molecular weight of 700 or less can be further increased.

[0469] In addition, in order to control the content of components with a number average molecular weight of 700 or less within the above range, it is preferable that the polyisocyanate component includes a polyisocyanate having a diketone group and a urethane group.

[0470] (Physical properties of polyisocyanate component (B))

[0471] 1. Viscosity

[0472] The lower limit of the viscosity of the polyisocyanate component (B) at 25°C is preferably 100 mPa·s, more preferably 140 mPa·s, further preferably 180 mPa·s, particularly preferably 200 mPa·s, and most preferably 220 mPa·s. On the other hand, the upper limit of the viscosity is preferably 1500 mPa·s, more preferably 1000 mPa·s, further preferably 800 mPa·s, particularly preferably 700 mPa·s, and most preferably 600 mPa·s.

[0473] That is, the viscosity of the polyisocyanate component (B) at 25°C is preferably 100 mPa·s or more and 1500 mPa·s or less, more preferably 140 mPa·s or more and 1000 mPa·s or less, further preferably 180 mPa·s or more and 800 mPa·s or less, particularly preferably 200 mPa·s or more and 700 mPa·s or less, and most preferably 220 mPa·s or more and 600 mPa·s or less.

[0474] By setting the viscosity above the aforementioned lower limit, the crosslinking property of the polyisocyanate component (B) can be further improved. On the other hand, by setting the viscosity below the aforementioned upper limit, the solid content concentration of the coating composition using the polyisocyanate component can be further increased.

[0475] Viscosity can be determined as follows: For the polyisocyanate component (B) purified to 99.5% by mass or higher of the non-volatile component (solid component), the viscosity is measured using an E-type viscometer (manufactured by TOKIMEC). Specifically, it can be determined using the method described in the examples below.

[0476] 2. Isocyanate group content

[0477] The lower limit of the isocyanate group content (NCO content) of the polyisocyanate component (B) is preferably 21.0% by mass, more preferably 21.5% by mass, and even more preferably 22.0% by mass. On the other hand, the upper limit of the NCO content is preferably 25.0% by mass, more preferably 24.0% by mass, and even more preferably 23.7% by mass.

[0478] That is, the NCO content of the polyisocyanate component (B) is preferably 21.0% by mass or more and 25.0% by mass or less, more preferably 21.5% by mass or more and 24.0% by mass or less, and even more preferably 22.0% by mass or more and 23.7% by mass or less.

[0479] By ensuring that the NCO content is above the lower limit mentioned above, the resulting multilayer coating laminate can have better coating properties, such as hardness. On the other hand, by ensuring that the NCO content is below the upper limit mentioned above, the yield of the polyisocyanate component (B) can be further improved.

[0480] The NCO content can be determined as follows: after neutralizing the isocyanate groups of the polyisocyanate component (B) with excess 2N amine, it is back-titrated with 1N hydrochloric acid.

[0481] It should be noted that the NCO content is a value relative to the solid content of polyisocyanate component (B). Furthermore, the solid content of polyisocyanate component (B) can be determined from the residue after heating polyisocyanate component (B) at 105°C for 3 hours.

[0482] 3. Number-average molecular weight

[0483] The lower limit of the number-average molecular weight of the solid component in the polyisocyanate component (B) is preferably 400, more preferably 430, even more preferably 460, and particularly preferably 480. On the other hand, the upper limit of the number-average molecular weight is preferably 1000, more preferably 800, even more preferably 700, and particularly preferably 600.

[0484] That is, the number average molecular weight of the solid component in the polyisocyanate component (B) is preferably 400 or more and 1000 or less, more preferably 430 or more and 800 or less, even more preferably 460 or more and 700 or less, and particularly preferably 480 or more and 600 or less.

[0485] By setting the number-average molecular weight to or above the aforementioned lower limit, the yield of the polyisocyanate component (B) tends to be further increased. On the other hand, by setting the number-average molecular weight to or below the aforementioned upper limit, the polyisocyanate component (B) is more easily incorporated into the first and second uncured coatings, which are the lower layers. As a result, the hardness of the resulting multilayer coating laminate containing the first, second, and third coatings tends to be better.

[0486] The polyisocyanate component (B) can use triisocyanate compounds.

[0487] Specifically, examples of triisocyanates include 4-isocyanate methyl-1,8-octamethylene diisocyanate (hereinafter sometimes referred to as "NTI") (molecular weight 251) disclosed in International Patent Publication No. 1996 / 17881 (Reference 1), 1,3,6-hexamethylene triisocyanate (hereinafter sometimes referred to as "HTI") (molecular weight 209) disclosed in Japanese Patent Application Publication No. 57-198760 (Reference 2), 2-isocyanate bis(2-isocyanate ethyl) glutarate (hereinafter sometimes referred to as "GTI") (molecular weight 311) disclosed in Japanese Patent Application Publication No. 4-1033 (Reference 3), and lysine triisocyanate (hereinafter sometimes referred to as "LTI") (molecular weight 267) disclosed in Japanese Patent Application Publication No. 53-135931 (Reference 4).

[0488] NTI, GTI, or LTI are preferred, with GTI or LTI being more preferred. By incorporating these triisocyanates, the water resistance of the multilayer coating laminate becomes good.

[0489] Triisocyanates can be used alone or in combination with polyisocyanates derived from aliphatic and alicyclic diisocyanates.

[0490] (NCO / OH)

[0491] When the second coating composition contains a polyisocyanate component (B), the NCO / OH ratio in the second coating composition is preferably 1.0 or less, more preferably less than 1.0. By keeping the NCO / OH ratio below the aforementioned upper limit, the polyisocyanate component in the third coating composition can be more easily and well integrated into the first and second coating compositions (the first uncured coating film and the second uncured coating film), allowing the first and second coating compositions to cure more efficiently. It should be noted that when the NCO / OH ratio in the first and second coating compositions is 1.0, the NCO / OH ratio in the third coating composition exceeds 1.0.

[0492] The NCO / OH ratio of the third coating composition is preferably 1.0 to 2.5, more preferably 1.2 to 2.0, and most preferably 1.4 to 1.8.

[0493] By setting the NCO / OH ratio to the range described above, the hardness of the multilayer coating laminate becomes satisfactory.

[0494] [Other ingredients]

[0495] The second and third coating compositions may contain other components in addition to the above-mentioned polyisocyanate components and hydroxyl-containing resin components.

[0496] Other components may include, for example, compounds containing unsaturated bonds, inactive compounds, metal atoms, basic amino compounds, carbon dioxide, halogen atoms, etc. These components may be present individually or in combination of two or more.

[0497] In the second and third coating compositions, the lower limit of the content of other components, based on the content of polyisocyanate components, can be set to 1.0 ppm by mass, 3.0 ppm by mass, 5.0 ppm by mass, or 10 ppm by mass.

[0498] On the other hand, the upper limit for the content of other components, based on the content of polyisocyanate, can be set at 1.0 × 10⁻⁶. 4 The mass fraction (ppm) can be set to 5.0 × 10⁻⁶. 3 The mass fraction (ppm) can be set to 3.0 × 10⁻⁶. 3 Mass in ppm can be set to 1.0 × 10⁻⁶. 3 Mass (ppm)

[0499] That is, in the second and third coating compositions, from the viewpoint of preventing discoloration during long-term storage and improving long-term storage stability, the content of other components, based on the content of polyisocyanate components, can be set to 1.0 ppm by mass or more and 1.0 × 10⁻⁶. 4 For values ​​below ppm, it can be set to 3.0 ppm or higher and 5.0 × 10⁻⁶. 3 For values ​​below ppm, it can be set to 5.0 ppm or higher and 3.0 × 10⁻⁶. 3 For values ​​below ppm, it can be set to 10 ppm or higher and 1.0 × 10⁻⁶. 3 Mass below ppm.

[0500] (Compounds containing unsaturated bonds)

[0501] The compound containing unsaturated bonds can be a carbon-carbon unsaturated bond, a carbon-nitrogen unsaturated bond, or a carbon-oxygen unsaturated bond. From the viewpoint of compound stability, compounds with double unsaturated bonds are preferred, and carbon-carbon double bonds (C=C) or carbon-oxygen double bonds (C=O) are more preferred. Furthermore, the carbon atom constituting the compound can be a carbon atom bonded to three or more atoms.

[0502] Typically, carbon-carbon double bonds are sometimes also carbon-carbon double bonds that make up aromatic rings, but the unsaturated bonds contained in compounds containing unsaturated bonds in coating compositions do not include carbon-carbon double bonds that make up aromatic rings.

[0503] Examples of compounds containing a carbon-oxygen double bond include, for example, carbonic acid derivatives. Examples of carbonic acid derivatives include, for example, urea compounds, carbonates, N-unsubstituted carbamates, and N-substituted carbamates.

[0504] (Inactive compound)

[0505] Inactive compounds are classified, for example, as compounds A through G.

[0506] Specifically, hydrocarbon compounds are classified as compounds A and B, ether compounds and thioether compounds are classified as compounds C to E below, halohydrocarbon compounds are classified as compounds F below, and silicon-containing hydrocarbon compounds, silicon-containing ether compounds, and silicon-containing thioether compounds are classified as compounds G below. It should be noted that compounds A to G listed here do not contain unsaturated bonds other than aromatic rings, and do not include the compounds mentioned above that contain unsaturated bonds.

[0507] Compound A: A straight-chain, branched, or cyclic aliphatic hydrocarbon compound.

[0508] Compound B: An aromatic hydrocarbon compound that is optionally substituted with an aliphatic hydrocarbon group.

[0509] Compound C: A compound having an ether structure or a thioether group and an aliphatic hydrocarbon group, which is a compound formed by the bonding of the same or different aliphatic hydrocarbon compounds through an ether structure or a thioether group.

[0510] Compound D: A compound having an ether structure or a thioether group and an aromatic hydrocarbon group, which is a compound formed by the bonding of the same or different aromatic hydrocarbon compounds through an ether structure or a thioether group.

[0511] Compound E: A compound having an ether structure or a thioether group and having aliphatic hydrocarbon groups and aromatic hydrocarbon groups.

[0512] Compound F: A halide formed by replacing at least one hydrogen atom of an aliphatic hydrocarbon compound or at least one hydrogen atom of an aromatic hydrocarbon compound with a halogen atom.

[0513] Compound G: A compound in which some or all of the carbon atoms of compounds A to E above are replaced by silicon atoms.

[0514] (Metal atom)

[0515] Metal atoms can exist as metal ions or as elemental metal atoms. There can be one type of metal atom or a combination of multiple metal atoms. Preferably, the metal atom exhibits a valence of 2 or higher but less than 4, and more preferably, it is selected from one or more metals chosen from iron, cobalt, nickel, zinc, tin, copper, and titanium.

[0516] (Basic amino compounds)

[0517] Basic amino compounds are derivatives of ammonia, and examples include compounds formed by substituting one hydrogen atom with an alkyl or aryl group (primary), two hydrogen atoms (secondary), and all three hydrogen atoms (tertiary). Among these, secondary or tertiary amino compounds are preferred as basic amino compounds, and aliphatic amines, aromatic amines, heterocyclic amines, or basic amino acids are more preferred.

[0518] (carbon dioxide)

[0519] Carbon dioxide can dissolve isocyanates at normal pressure or in a pressure vessel under pressure. When using carbon dioxide containing moisture, it can sometimes cause hydrolysis of isocyanates; therefore, the moisture content in the carbon dioxide should preferably be managed as needed.

[0520] (halogen atom)

[0521] From the viewpoint of preventing staining, the halogen atom content in the first coating composition and the second coating composition is preferably 1.0 × 10⁻⁶. 2 The mass is less than ppm. The halogen atom is not particularly limited, but preferably at least one of chlorine and bromine atoms, more preferably at least one ion or compound selected from the group consisting of chloride ions, bromide ions, hydrolyzable chlorine, and hydrolyzable bromine. Examples of hydrolyzable chlorine include carbamoyl chloride compounds formed by the addition of hydrogen chloride to an isocyanate group, and examples of hydrolyzable bromine include carbamoyl bromide compounds formed by the addition of hydrogen bromide to an isocyanate group.

[0522] Melamine-based curing agent

[0523] The second and third coating compositions may, as needed, further include a melamine-based curing agent in addition to the aforementioned polyisocyanate and hydroxyl-containing resin components. Examples of melamine-based curing agents include, for instance, all-alkyl, hydroxymethyl alkyl, and imino alkyl types.

[0524] [Organic solvents]

[0525] Furthermore, the aforementioned polyisocyanate component (B), the aforementioned hydroxyl-containing resin component, the second coating composition, and the third coating composition can all be mixed with organic solvents for use. As the organic solvent, it is preferable to use an organic solvent that does not have functional groups that react with hydroxyl and isocyanate groups. Additionally, it is preferable to use one that is compatible with the polyisocyanate component. Such organic solvents can be those commonly used as coating solvents; specifically, examples include ester compounds, ether compounds, ketone compounds, aromatic compounds, ethylene glycol dialkyl ether compounds, polyethylene glycol dicarboxylic acid ester compounds, hydrocarbon solvents, and aromatic solvents.

[0526] [Other Additives]

[0527] In addition to the above-mentioned polyisocyanate component and hydroxyl-containing resin component, the second and third coating compositions may further include, within the scope of purpose and use without impairing the effect of this embodiment, various additives used in this technical field, such as curing accelerators, pigments, leveling agents, antioxidants, ultraviolet absorbers, light stabilizers, plasticizers, and surfactants.

[0528] Examples of catalysts used for curing include metal salts and tertiary amines.

[0529] Examples of metal salts include dibutyltin dilaurate, tin 2-ethylhexanoate, zinc 2-ethylhexanoate, and cobalt salts.

[0530] Examples of tertiary amines include: triethylamine, pyridine, methylpyridine, benzyl dimethylamine, N,N-dimethylcyclohexylamine, N-methylpiperidine, pentamethyldiethylenetriamine, N,N'-endo-ethylenepiperazine, and N,N'-dimethylpiperazine.

[0531] [Method for manufacturing coating composition]

[0532] The second coating composition can be obtained by mixing the above-mentioned hydroxyl-containing resin component, the above-mentioned polyisocyanate component (C) used as needed, and various additive components using known methods.

[0533] The third coating composition can be obtained by mixing the above-mentioned polyisocyanate component (B), the above-mentioned hydroxyl-containing resin component, and various additive components used as needed, using known methods.

[0534] For example, in manufacturing a water-based coating composition, various additives are added as needed to a hydroxyl-containing resin component or its aqueous dispersion or solution. Next, the aforementioned polyisocyanate component or its aqueous dispersion is added as a curing agent, and water and solvent are further added as needed to adjust the viscosity. Then, forced stirring is performed using a stirring device, thereby obtaining the water-based coating composition.

[0535] In manufacturing solvent-based coating compositions, various additives are first added to the hydroxyl-containing resin component or its solvent dilution as needed. Next, the aforementioned polyisocyanate component is added as a curing agent, and solvent is further added as needed to adjust the viscosity. Then, the mixture is stirred manually or using a stirring device such as a mazelar, thereby obtaining the solvent-based coating composition.

[0536] In this embodiment, from the viewpoint of protecting the Earth's environment, a method for manufacturing a water-based coating composition is preferred.

[0537] (Object to be painted)

[0538] The material to be coated is not particularly limited, and examples include molded products made from raw materials such as metal (steel plates, surface-treated steel plates, etc.), plastics, wood, and inorganic materials. Furthermore, the shape of these molded products is not particularly limited; they can be thin items such as films, sheets, and plates, or thick items such as cylinders and three-dimensional structures. Hollow items such as tubes are also acceptable.

[0539] Furthermore, the object to be coated can be a coating film. Besides coating films formed by applying and curing a main agent such as a polyol with a curing agent such as a (terminated) polyisocyanate or melamine, uncured coating films before curing can also be listed. In the method for forming a multilayer coating laminate described later, the object to be coated is preferably an uncured coating film, which is cured by heating the first, second, and third uncured coating films together, thus forming a cured coating film.

[0540] (use)

[0541] The multilayer coating laminate of this embodiment is useful, for example, as a base coat (lower coat), intermediate coat, or upper coat for raw materials such as metals (steel plates, surface-treated steel plates, etc.), plastics, wood, and inorganic materials. Furthermore, it is also useful as a laminate for imparting aesthetic and decorative properties, weather resistance, acid resistance, rust prevention, and crack resistance to pre-coated metals including rust-resistant steel plates, automotive coatings, etc.

[0542] Example

[0543] The following specific examples and comparative examples illustrate this embodiment in more detail, but this embodiment is not limited by the following examples and comparative examples as long as it does not depart from its spirit. The physical properties of the polyisocyanate components and the evaluation of the coating film in the examples and comparative examples were measured and evaluated as described below. It should be noted that, unless otherwise specified, "parts" and "%" represent "parts by mass" and "% by mass".

[0544] <Determination Method>

[0545] (Physical Properties) Isocyanate Group Content (NCO Group Content)

[0546] The substrate coating compositions obtained in the examples and comparative examples were used as samples, and the isocyanate group content was determined using the method shown below.

[0547] (1) Take 1g of the sample into a 200mL Erlenmeyer flask and add 20mL of toluene to the flask to dissolve the sample.

[0548] (2) Then, add 20 mL of 2.0 N di-n-butylamine-toluene solution to the above flask and let it stand for 15 minutes.

[0549] (3) Add 70 mL of 2-propanol to the above flask, dissolve, and obtain a solution.

[0550] (4) For the solution obtained in (3) above, titrate with 1 mol / L hydrochloric acid to determine the titration amount of the sample.

[0551] (5) Determine the blank titration amount by performing the same method as (1) to (3) above without adding a sample.

[0552] The isocyanate group content is calculated using the formula shown below, based on the sample titration amount and blank titration amount obtained above.

[0553] Isocyanate group content [mass %] = (blank titration amount - sample titration amount) × 42 / [sample mass (1g) × 1000] × 100

[0554] (Physical property) Calculation method for a specific molar ratio

[0555] The molar ratios of iminooxadiazine dione, urea dione, urea carbamate, and isocyanurate groups were determined using a 13C NMR spectrometer (Bruker Biospin Avance 600). Specific determination conditions are as follows.

[0556] 13 C-NMR apparatus: AVANCE 600 (manufactured by Bruker)

[0557] Cryo Probe (manufactured by Bruker)

[0558] Cryo Probe

[0559] CPDUL

[0560] 600S3-C / HD-05Z

[0561] Resonant frequency: 150MHz

[0562] Concentration: 60 wt / vol%

[0563] Displacement reference: CDCl3 (77ppm)

[0564] Total number of times: 10,000

[0565] Pulse program: zgpg30 (complete proton decoupling, wait time 2 seconds)

[0566] Divide the integral value of the following signal by the measured number of carbon atoms, and use the result to determine the molar ratio.

[0567] Molar amount (mol%) of iminooxadiazine dione group: approximately 144.6 ppm: integral value ÷ 1

[0568] Molar amount of isocyanurate group (mol%), expressed as "A": Approximately 148.6 ppm: Integral value ÷ 3

[0569] Molar amount of diurea group (mol%), expressed in "C": Approximately 157.5 ppm: Integral value ÷ 2

[0570] The molar ratios obtained are as follows: for each molar ratio, the value is determined using the coating composition for the substrate as a sample.

[0571] Molar ratio: (B+C) / (A+B+C)

[0572] (Physical Properties) Content of urea diketone dimer of diisocyanate monomer

[0573] Using the base coating composition as a sample, the area ratio of the diisocyanate monomer to the urea diketone dimer relative to the total area of ​​the base coating composition was determined by gel permeation chromatography using the apparatus described below, and the obtained ratio was taken as the content of the diisocyanate monomer urea diketone dimer.

[0574] (Physical properties) Number-average molecular weight and weight-average molecular weight

[0575] The number-average molecular weight and weight-average molecular weight are the polystyrene reference molecular weights determined by gel permeation chromatography (GPC) using the apparatus described below.

[0576] To determine the number-average molecular weight of polyisocyanates, polyisocyanates before end-capping with a capping agent were used as the test sample.

[0577] For weight-average molecular weight, end-capped polyisocyanate compositions or polyhydroxy compounds are used directly as the test samples. The test conditions are shown below.

[0578] (Measurement conditions)

[0579] Device: Tosoh Corporation, HLC-802A

[0580] Column: Tosoh Corporation, G1000HXL x 1 piece

[0581] G2000HXL × 1 piece

[0582] G3000HXL × 1 piece

[0583] Support: Tetrahydrofuran

[0584] Test method: Differential refractometer

[0585] (Physical Properties) Average Isocyanate Number

[0586] The average number of isocyanate groups (average NCO number) of a polyisocyanate is calculated using the following formula. It should be noted that in the formula, "Mn" represents the number-average molecular weight of the polyisocyanate, and "NCO content" represents the isocyanate group content of the polyisocyanate, using the values ​​calculated above.

[0587] Average isocyanate content = (Mn × NCO content × 0.01) / 42

[0588] [evaluate]

[0589] (Water dispersibility of polyisocyanate component (A))

[0590] The polyisocyanate component (A) obtained in the examples and comparative examples was used as a sample, and its water dispersibility was evaluated using the method shown below.

[0591] (1) Determine the mass (W0g) of a 100mL flask and Yoshino paper.

[0592] (2) Collect the base coating composition, which is converted to 16g (W2g) of solid components, into a 100mL flask and add 24g of deionized water.

[0593] (3) Use a propeller blade to stir the solution in the 100mL flask at 200rpm for 3 minutes, and then filter it with the Yoshino paper weighed in (1).

[0594] (4) Combine the filter residue remaining on the Yoshino paper with the residue remaining in the 100mL flask, heat in a dryer at 105℃ for 1 hour, and calculate the mass (g) (W1g).

[0595] (5) Use the following formula to determine the proportion of the base coating composition dispersed in water. It should be noted that in the formula, Y is the non-volatile component (mass %).

[0596] "Percentage dispersed in water (mass%)"

[0597] ={1-(W2(g)-W0(g)) / (W2(16g)×Y)}×100

[0598] (6) Next, evaluate the water dispersibility according to the following evaluation criteria.

[0599] (Evaluation Criteria)

[0600] ◎:More than 95%

[0601] ○: 90% or more but less than 95% by mass

[0602] △: 80% or more but less than 90% by mass

[0603] ×: Less than 80% by mass

[0604] [evaluate]

[0605] (Applicable period)

[0606] Infrared absorption spectroscopy was measured using an FT / IR4200typeA (trade name) manufactured by Nippon Spectrophotometer Co., Ltd. (detector: TGS, number of cycles: 16, resolution: 4 cm⁻¹). -1 The absorption peak relative to isocyanurate (wavenumber 1686 cm⁻¹) in the data. -1 The isocyanate absorption peak (wavenumber 2271 cm⁻¹) is located near the target area. -1 The concentration change of isocyanate groups in each substrate coating composition is calculated by comparing the intensity ratio (near the same location). The substrate coating composition is set to 0 hours immediately after preparation. The peak intensity of isocyanate at this time is divided by the peak intensity of isocyanurate at the same time, which is set to X0. The peak intensity ratio after n hours is calculated as Xn, and the "isocyanate group retention rate" is calculated as Xn / X0. The pot life is evaluated according to the following evaluation criteria, based on the time during which the isocyanate group retention rate can be maintained at 80% or more.

[0607] (Evaluation Criteria)

[0608] ○: 4 hours or more

[0609] △: More than 2 hours but less than 4 hours

[0610] ×: Less than 2 hours

[0611] (Coating hardness: Koenig)

[0612] Each substrate coating composition was applied to a glass plate with a dry film thickness of 40 μm, and then dried at 80°C for 30 minutes to obtain a resin film. The Koenegg hardness (in degrees) of the coated plates obtained in each example and comparative example was measured using an Erichsen pendulum hardness tester. The coating hardness was evaluated according to the following evaluation criteria: Koenegger.

[0613] (Evaluation Criteria)

[0614] ◎: More than 100 times

[0615] ○: 95 times or more but less than 100 times

[0616] ×: Less than 95 times

[0617] (Curing properties)

[0618] Each substrate coating composition was applied to a polypropylene (PP) sheet to a dry film thickness of 40 μm, and then dried at 80°C for 30 minutes to obtain a resin film. The gel rate of the obtained resin film was determined. The gel rate was expressed as a percentage (mass%) of the undissolved portion of the resin film after immersion in acetone at 23°C for 24 hours, divided by the mass before immersion. Curing properties were evaluated according to the following criteria.

[0619] (Evaluation Criteria)

[0620] ○: More than 90%

[0621] △: 85% or more but less than 90%

[0622] ×: Less than 85%

[0623] <Synthesis of Sulfonate Ammonium Salts>

[0624] [Synthesis example 1]

[0625] (Synthesis of HES / TBA)

[0626] At room temperature (around 23°C), 10 parts by mass of 1-propanol were added to 20 parts by mass of a 70% by mass aqueous solution of 2-hydroxyethanesulfonic acid (hereinafter sometimes simply referred to as "HES"), and the mixture was stirred to obtain a solution. Tributylamine (hereinafter sometimes simply referred to as "TBA") was then measured in a molar equivalent ratio to HES of 1, diluted with the same amount of 1-propanol, and the resulting liquid was added dropwise to the stirred solution. One hour after the start of the addition, stirring was stopped, and the solution was dehydrated and desolventized using an evaporator to obtain a 99.8% by mass 2-hydroxyethanesulfonic acid tributylamine salt (hereinafter sometimes simply referred to as "HES / TBA").

[0627] Synthesis of Polyisocyanates

[0628] [Synthesis example 2]

[0629] (Synthesis of polyisocyanate P-1)

[0630] A four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen inlet tube, and dropping funnel was placed under a nitrogen atmosphere. 1000 g of HDI and 4.0 g of isobutanol were added, and the temperature inside the stirred reactor was maintained at 70°C. Tetramethylammonium octanoate was added, and phosphoric acid was added to stop the reaction when the NCO content of the reaction solution reached 36.0% by mass. The temperature was then raised to 160°C and maintained for 1 hour. After filtering the reaction solution, unreacted HDI was removed using a thin-film evaporator to obtain polyisocyanate P-1. The obtained polyisocyanate P-1 had a viscosity of 900 mPa·s at 25°C and an isocyanate group content of 22.3%.

[0631] [Synthesis example 3]

[0632] (Synthesis of polyisocyanate P-2)

[0633] A four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen inlet tube, and dropping funnel was placed under a nitrogen atmosphere. 1000 g of HDI and 4.0 g of isobutanol were added, and the temperature inside the stirred reactor was maintained at 70°C. Tetramethylammonium octanoate was added, and phosphoric acid was added to stop the reaction when the NCO content of the reaction solution reached 34.7% by mass. The temperature was then raised to 160°C and maintained for 1 hour. After filtering the reaction solution, unreacted HDI was removed using a thin-film evaporator to obtain polyisocyanate P-2. The obtained polyisocyanate P-2 had a viscosity of 1200 mPa·s at 25°C and an isocyanate group content of 22.6%.

[0634] [Synthesis Example 4]

[0635] (Synthesis of polyisocyanate P-3)

[0636] A four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen inlet tube, and dropping funnel was placed under a nitrogen atmosphere. 1000 g of HDI and 4.0 g of isobutanol were added, and the temperature inside the stirred reactor was maintained at 70°C. Tetramethylammonium octanoate was added, and phosphoric acid was added to stop the reaction when the NCO content of the reaction solution reached 38.5% by mass. The reaction solution was then filtered, and unreacted HDI was removed using a thin-film evaporator to obtain polyisocyanate P-3. The obtained polyisocyanate P-3 had a viscosity of 2700 mPa·s at 25°C and an isocyanate group content of 21.7% by mass.

[0637] [Synthesis example 5]

[0638] (Synthesis of polyisocyanate P-4)

[0639] A four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen inlet tube, and dropping funnel was placed under a nitrogen atmosphere. 1000 g of HDI and 4.0 g of isobutanol were added, and the temperature inside the stirred reactor was maintained at 70°C. Tetramethylammonium octanoate was added, and phosphoric acid was added to stop the reaction when the NCO content of the reaction solution reached 45.5% by mass. The temperature was then raised to 160°C and maintained for 1 hour. After filtering the reaction solution, unreacted HDI was removed using a thin-film evaporator to obtain polyisocyanate P-4. The obtained polyisocyanate P-4 had a viscosity of 500 mPa·s at 25°C and an isocyanate group content of 23.3% by mass.

[0640] [Synthesis example 6]

[0641] (Synthesis of polyisocyanate P-5)

[0642] A four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen inlet tube, and dropping funnel was placed under a nitrogen atmosphere. 1000 g of PDI and 4.0 g of isobutanol were added, and the temperature inside the stirred reactor was maintained at 70°C. Tetramethylammonium octanoate was added, and phosphoric acid was added to stop the reaction when the NCO content of the reaction solution reached 42.5% by mass. The reaction solution was then filtered, and unreacted HDI was removed using a thin-film evaporator to obtain polyisocyanate P-1. The resulting polyisocyanate P-5 had a viscosity of 2000 mPa·s at 25°C and an isocyanate group content of 25.0% by mass.

[0643] [Synthesis Example 7]

[0644] (Synthesis of polyisocyanate P-6)

[0645] 5.7 parts by mass of polyethylene glycol monomethyl ether (manufactured by Nippon Emulsifier Co., Ltd., trade name "MPG-130") with an average repeating number of 9.4 of ethylene oxide was added to 94.3 parts by mass of polyisocyanate P-4 obtained in Synthetic Example 5 (molar equivalent ratio of isocyanate group / hydroxyl group = 39). The reaction was carried out under nitrogen atmosphere and stirred at 90°C for 6 hours. After the reaction was completed, polyisocyanate P-6 was obtained.

[0646] [Synthesis example 8]

[0647] (Synthesis of polyisocyanate P-7)

[0648] In a four-necked flask equipped with a stirrer, thermometer, and gas inlet tube, 1060 g of 4-aminomethyl-1,8-octamethylenediamine (hereinafter sometimes referred to as "triamine") was dissolved in 1500 g of methanol. While cooling, 1800 mL of 35% hydrochloric acid was slowly added dropwise. The mixture was then concentrated under reduced pressure to remove methanol and water, and dried at 60 °C / 5 mmHg for 24 hours to obtain a white solid triamine hydrochloride. 650 g of the obtained triamine hydrochloride was powdered and suspended in 5000 g of o-dichlorobenzene, with the reaction mixture being heated while mixing. Phosgene was then introduced at a rate of 200 g / h when the reaction mixture reached 100 °C, and the temperature was continuously increased. The temperature was then maintained at 180 °C, with phosgene continuously introduced for 12 hours. Next, after removing dissolved phosgene and solvent under reduced pressure, vacuum distillation was performed to obtain 420g of colorless and transparent NTI with a boiling point above 161℃ and below 163℃ / 1.2mmHg. The NTI contained 50.0% NCO by mass.

[0649] [Synthesis Example 9]

[0650] (Synthesis of polyisocyanate P-8)

[0651] 122.2 g of ethanolamine, 100 ml of o-dichlorobenzene, and 420 ml of toluene were added to a four-necked flask equipped with a stirrer, thermometer, and gas inlet tube. Ice-cooled hydrogen chloride gas was introduced to convert the ethanolamine into hydrochloride. Then, 182.5 g of lysine hydrochloride was added, and the reaction mixture was heated to 80°C to dissolve the ethanolamine hydrochloride. Hydrogen chloride gas was then introduced to form lysine dihydrochloride. Hydrogen chloride gas was then introduced at a rate of 20–30 ml / min, and the reaction mixture was heated to 116°C and maintained at this temperature until water no longer distilled off. The resulting reaction mixture was recrystallized in a mixture of methanol and ethanol to obtain 165 g of lysine β-aminoethyl ester trihydrochloride. 100 g of this lysine β-aminoethyl ester trihydrochloride was prepared as a micropowder and suspended in 1200 ml of o-dichlorobenzene. The reaction mixture was heated while mixing, and phosgene was introduced at a rate of 0.4 mol / h at the time point reaching 120°C. This was maintained for 10 hours, and then the temperature was increased to 150°C. Most of the suspension dissolved. After cooling, it was filtered, and the dissolved phosgene and solvent were removed by distillation under reduced pressure, followed by vacuum distillation to obtain 80.4 g of colorless and transparent LTI with a boiling point of 155–157 °C / 0.022 mmHg. Its NCO content was 47.1% by weight.

[0652] [Synthesis Example 10]

[0653] (Synthesis of polyisocyanate P-9)

[0654] A four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen inlet tube, and dropping funnel was set to a nitrogen atmosphere. 50 parts by mass of polyisocyanate P-4 obtained in Synthesis Example 5 and 50 parts by mass of polyisocyanate P-7 obtained in Synthesis Example 8 were mixed at room temperature to obtain polyisocyanate P-9.

[0655] [Synthesis Example 11]

[0656] (Synthesis of polyisocyanate P-10)

[0657] A four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen inlet tube, and dropping funnel was set to a nitrogen atmosphere. 50 parts by mass of polyisocyanate P-4 obtained in Synthesis Example 5 and 50 parts by mass of polyisocyanate P-8 obtained in Synthesis Example 8 were mixed at room temperature to obtain polyisocyanate P-10.

[0658] [Synthesis Example 12]

[0659] (Synthesis of polyisocyanate P-11)

[0660] A four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen inlet tube, and dropping funnel was set to a nitrogen atmosphere. 50 parts by mass of polyisocyanate P-3 obtained in Synthesis Example 4 and 50 parts by mass of polyisocyanate P-7 obtained in Synthesis Example 8 were mixed at room temperature to obtain polyisocyanate P-11.

[0661] <Synthesis of Polyisocyanate Component (A)>

[0662] [Synthesis Example 13]

[0663] (Synthesis of polyisocyanate component (A)-1)

[0664] 12.0 parts by mass of 2-hydroxyethanesulfonic acid tributylamine salt (HES / TBA) obtained in Synthesis Example 1 were added to 100 parts by mass of polyisocyanate P-3 obtained in Synthesis Example 4, and the reaction was carried out by stirring at 120°C for 3 hours under a nitrogen atmosphere. After the reaction was completed, 112 parts by mass of polyisocyanate P-1 obtained in Synthesis Example 2 were added and mixed to obtain polyisocyanate component (A)-1.

[0665] [Synthesis Example 14]

[0666] (Synthesis of polyisocyanate component (A)-2)

[0667] 6.3 parts by mass of 2-hydroxyethanesulfonic acid tributylamine salt (HES / TBA) obtained in Synthesis Example 1 were added to 100 parts by mass of polyisocyanate P-3 obtained in Synthesis Example 4, and the reaction was carried out by stirring at 120°C for 3 hours under a nitrogen atmosphere. After the reaction was completed, 26.6 parts by mass of polyisocyanate P-4 obtained in Synthesis Example 5 were added and mixed to obtain polyisocyanate component (A)-2.

[0668] [Synthesis Example 15]

[0669] (Synthesis of polyisocyanate component (A)-3)

[0670] 12.0 parts by mass of 3-cyclohexylaminopropanesulfonic acid (hereinafter sometimes simply referred to as "CAPS") and 7.0 parts by mass of N,N-dimethylcyclohexylamine (hereinafter sometimes simply referred to as "DMCHA") were added to 100 parts by mass of polyisocyanate P-3 obtained in Synthesis Example 4, and the reaction was carried out under nitrogen atmosphere by reflux and stirring at 80°C for 5 hours. After the reaction was completed, 120 parts by mass of polyisocyanate P-2 obtained in Synthesis Example 3 were added and mixed to obtain polyisocyanate component (A)-3.

[0671] [Synthesis Example 16]

[0672] (Synthesis of polyisocyanate component (A)-4)

[0673] Add 4.2 parts by mass of 2-hydroxyethanesulfonic acid tributylamine salt (HES / TBA) obtained in Synthesis Example 1 to 100 parts by mass of polyisocyanate P-4 obtained in Synthesis Example 5, and react by stirring at 120°C for 3 hours under a nitrogen atmosphere to obtain polyisocyanate component (A)-4.

[0674] [Synthesis Example 17]

[0675] (Synthesis of polyisocyanate component (A)-5)

[0676] 1.1 g of 1,3-butanediol (1,3-BG) and 4.2 parts by mass of 2-hydroxyethanesulfonic acid tributylamine salt (HES / TBA) obtained in Synthesis Example 1 were added to 100 parts by mass of polyisocyanate P-4 obtained in Synthesis Example 5, and the reaction was carried out by stirring at 120°C for 3 hours under a nitrogen atmosphere to obtain polyisocyanate component (A)-5.

[0677] [Synthesis Example 18]

[0678] (Synthesis of polyisocyanate component (A)-6)

[0679] 6.4 parts by mass of 2-hydroxyethanesulfonic acid tributylamine salt (HES / TBA) obtained in Synthesis Example 1 were added to 100 parts by mass of polyisocyanate P-3 obtained in Synthesis Example 4, and the reaction was carried out by stirring at 120°C for 3 hours under a nitrogen atmosphere. After the reaction was completed, 26.6 parts by mass of polyisocyanate P-6 obtained in Synthesis Example 7 were added and mixed to obtain polyisocyanate component (A)-6.

[0680] [Synthesis Example 19]

[0681] (Synthesis of polyisocyanate component (A)-7)

[0682] 7.5 parts by mass of 2-hydroxyethanesulfonic acid tributylamine salt (HES / TBA) obtained in Synthesis Example 1 were added to 100 parts by mass of polyisocyanate P-3 obtained in Synthesis Example 4, and the reaction was carried out by stirring at 120°C for 3 hours under a nitrogen atmosphere to obtain polyisocyanate component (A)-7.

[0683] The physical properties and evaluation results of each polyisocyanate component (A) are shown in Table 1.

[0684] Table 1

[0685]

[0686] <Preparation of coating compositions for substrates>

[0687] [Example 1]

[0688] (Synthesis of substrate coating composition 0-a1)

[0689] 40 g of an acrylic polyol aqueous dispersion (product name: Setaqua 6510, hydroxyl value per unit resin: 138 mg KOH / g, manufactured by Allnex) was measured into a container. Next, the polyisocyanate component (A)-1 obtained in Synthesis Example 13 was added at a ratio of 1.7 (NCO / OH) of the molar amount of isocyanate groups to the molar amount of hydroxyl groups in the acrylic polyol aqueous dispersion. Then, deionized water was added at a ratio of 42% by mass of the solids content in the substrate coating composition, and the mixture was stirred at 600 rpm for 10 minutes using a propeller blade to obtain substrate coating composition 0-a1. The prepared substrate coating composition was evaluated using the method described above. The results are shown in Table 2.

[0690] [Examples 2-7, Comparative Example 1]

[0691] The types of polyisocyanate component (A) are shown in Table 2. Otherwise, substrate coating compositions 0-a2 to 0-a7 and 0-b1 were obtained using the same method as in Example 1. The prepared substrate coating compositions were evaluated using the methods described above. The results are shown in Table 2.

[0692] [Comparative Example 2]

[0693] 40 g of an acrylic polyol aqueous dispersion (product name: Setaqua 6510, hydroxyl value per unit resin: 138 mg KOH / g, manufactured by Allnex) was measured into a container. Next, 9.2 g of melamine resin (manufactured by Allnex Japan, product name "CYMEL 325", imino-methylated melamine resin) was added. Then, deionized water was added at a ratio of 42% by weight of the solids content in the substrate coating composition, and the mixture was stirred at 600 rpm for 10 minutes using a propeller blade to obtain substrate coating composition 0-b2. The prepared substrate coating composition 0-b2 was evaluated using the method described above. The results are shown in Table 2.

[0694] Table 2

[0695]

[0696] As shown in the results above, the substrate coating compositions of Examples 1 to 7 that satisfy the composition of the present invention have good pot life, and the single-layer cured film manufactured using the substrate coating compositions has good hardness and curability.

[0697] On the other hand, the hardness result of Comparative Example 1 was low.

[0698] Although Comparative Example 2 has a good pot life, it has low hardness and curing properties.

[0699] <Manufacturing of Multilayer Coated Laminates>

[0700] [Example 8]

[0701] (Preparation of sample coated plate T-a1)

[0702] (Preparation of the first coating composition)

[0703] Measure 87.9 parts of deionized water, 245.0 parts of titanium oxide pigment (English product name: Ti-Pure R-902+, Chemours), 17.2 parts of water-based wetting and dispersing agent (product name: BYK-190, BYK), and 0.7 parts of defoamer (product name: Tego902W) into a container and stir with a propeller blade at 2700 rpm for 120 minutes.

[0704] After stirring, add 650 parts of an acrylic polyol aqueous dispersion (product name: Setaqua 6510, hydroxyl value per unit resin: 138 mg KOH / g, manufactured by Allnex), and stir further at 1500 rpm for 30 minutes. While stirring, add 2.0 parts of a silicone defoamer (product name: BYK-024, manufactured by BYK), 0.7 parts of a defoamer (Tego902W), and 1.0 part of a surface conditioner (product name: BYK-346, manufactured by BYK), and stir for 15 minutes. Then, add 3.0 parts of a viscosity modifier (product name: Acrysol RM-8W, manufactured by Dow Chemical), and stir for 15 minutes.

[0705] Next, polyisocyanate component (A)-1 obtained in Synthesis Example 13 was added at a ratio of 1.7, where the molar amount of isocyanate groups in polyisocyanate component (A)-1 was relative to the molar amount of hydroxyl groups in the acrylic polyol aqueous dispersion (NCO / OH). Deionized water was added at a ratio of 43% by mass of the solids content in the coating composition, and then 2-(dimethylamino)ethanol was added to achieve a pH of 8.0 for the coating composition. The mixture was stirred at 600 rpm for 10 minutes using a propeller blade to obtain the first coating composition 1-a1 with a viscosity of 55 seconds as measured by a Ford cup No. 4 at 20°C.

[0706] (Preparation of the second coating composition 2-1)

[0707] As the second coating composition 2-1, water-based-2 (black) (product name: nax E-CUBE WB water-based color base (silent black), manufactured by Nippon Paint Holdings Co., Ltd.) is used.

[0708] (Preparation of the third coating composition)

[0709] Acrylic polyol (manufactured by Allnex, "SETALUX DA665BA / X (trade name)") and polyisocyanate P-3 obtained in Synthesis Example 4 as polyisocyanate component (B) were combined as additives with a molar ratio of isocyanate group / hydroxyl group (NCO / OH) of 1.7. BYK-331 0.10 wt% / resin amount, TINUVIN 292 1.0 wt% / resin amount, and TINUVIN 384-2 1.5 wt% / resin amount were diluted with propylene glycol monomethyl ether acetate / solvent naphtha (mass ratio 50 / 50) at a spray viscosity of 27 seconds (ISO 5 cup) to prepare the third coating composition.

[0710] (Manufacturing of a 3-layer coated laminate)

[0711] Using a cationic electrocoated steel sheet as a substrate, the first coating composition, which serves as the base coating composition, is sprayed with a dry film thickness of 18 μm and left to stand at room temperature for 5 minutes to form a first uncured coating film.

[0712] Subsequently, water-based-2 (black sapphire color), which is the second coating composition, is sprayed onto the first uncured coating film with a dry film thickness of 13 μm. After standing at room temperature for 5 minutes, it is preheated at 70°C for 5 minutes to obtain a laminate formed by sequentially stacking the substrate, the first uncured coating film, and the second uncured coating film.

[0713] Then, the third coating composition prepared by the above method was sprayed onto the second uncured coating after preheating, with a dry film thickness of 40 μm. After drying at 80°C for 30 minutes, it was dried at 3°C ​​and 50% humidity for 24 hours to obtain a sample coated plate T-a1 as a laminate with multiple coating films.

[0714] [Examples 9-21 and Comparative Example 3]

[0715] (Preparation of sample coated plates T-a2~T-a14 and T-b1)

[0716] The type of polyisocyanate component (A) in the first coating composition and the polyisocyanate component (B) in the third coating composition were changed to the materials shown in Table 3. Otherwise, a sample coated plate having a three-layer coating laminate was obtained using the same method as in Example 8.

[0717] [Example 22]

[0718] (Preparation of sample coated plate T-a15)

[0719] The type of polyisocyanate component (A) in the first coating composition and the polyisocyanate component (B) in the third coating composition were changed to the materials shown in Table 3. The second coating composition 2-2, which is mixed with the end-capped polyisocyanate component (D) described later, was used as the second coating composition. Otherwise, the sample coated plate having a 3-layer coating laminate was obtained by the same method as in Example 8.

[0720] (Preparation of the terminated polyisocyanate component (D)-1 used in Example 22)

[0721] In a four-necked flask equipped with a thermometer, stirring blades, and a reflux condenser, 100 parts by mass of HDI and 5.2 parts by mass of a polyester polyol derived from trihydric alcohol and ε-caprolactone (manufactured by Dassell Chemicals, "Placcel 303" (trade name), average functional group number: 3, number average molecular weight 300) were added under a nitrogen atmosphere. The temperature inside the reactor was maintained at 88°C for 1 hour with stirring to carry out the carbamate reaction. The temperature inside the reactor was then maintained at 62°C, and a tetramethylammonium octanoate catalyst for isocyanurate esterification was added. Phosphoric acid was added to stop the reaction at a yield of 51% by mass. The reaction solution was filtered, and unreacted HDI was removed using a thin-film evaporator to obtain an isocyanurate-type polyisocyanate. The obtained polyisocyanate had an NCO content of 18.8% by mass, a number average molecular weight of 1180, and an average isocyanate group number of 5.3. Furthermore, 1H-NMR analysis of the obtained polyisocyanate confirmed the presence of isocyanurate groups.

[0722] The polyisocyanate obtained above (100 parts by weight), dipropylene glycol dimethyl ether (DPDM) (13 parts by weight), methoxy polyethylene glycol (MPG-081, ethylene oxide repeating unit: 15, manufactured by Nippon Emulsifier Co., Ltd.) (representing 5 mol% of isocyanate groups per 100 mol% of polyisocyanate P-2), and 2-ethylhexyl phosphate (JP-508T, manufactured by Jōhoku Chemical Industry Co., Ltd.) (0.08 parts by weight) were mixed and stirred at 120°C for 2 hours to obtain a hydrophilic compound – modified polyisocyanate. The obtained polyisocyanate P-2 had an NCO content of 14.0% by weight and an average isocyanate group number of 5.0.

[0723] The hydrophilic compound modified polyisocyanate obtained above was added in the following proportions: 100 parts by mass; diisopropyl malonate: 63.9 parts by mass (102 mol% relative to 100 mol% of NCO groups); and dipropylene glycol dimethyl ether (DPDM) was further added to prepare the product with a solid content of 60% by mass. Next, a methanol solution containing sodium methoxide (28 mol% relative to the total mass of the solution): 1.0 part by mass was added dropwise while stirring. The external bath was then adjusted to a solution temperature of 55°C, and the end-capping reaction was carried out at 55°C for 5 hours to obtain a end-capped polyisocyanate intermediate with a solid content of 60% by mass. Then, 75 parts by mass of 2-methyl-2-butanol (250 mol% relative to the end-capped isocyanate groups) were added, and the reaction was carried out at 80°C for 3 hours while removing the generated isopropanol by atmospheric distillation. Subsequently, isopropanol and 2-methyl-2-butanol were 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% by mass, yielding the capped polyisocyanate component (D)-1.

[0724] The specific structure and composition of the manufactured end-capped polyisocyanate component (D)-1 are shown in Table 3.

[0725] (Preparation of the second coating composition 2-2 used in Example 22)

[0726] To water-based-2 (black) (product name: nax E-CUBE WB water-based color base (silent black), manufactured by NipponPaint Holdings Co., Ltd.), the above-prepared end-capped polyisocyanate component (D)-1 was added at a ratio of 2% by mass, and then deionized water was added at a ratio of 25% by mass of solids. The mixture was stirred at 600 rpm for 10 minutes using a propeller blade to obtain the second coating composition 2-2.

[0727] [Example 23]

[0728] (Preparation of sample coated plate T-a16)

[0729] The type of polyisocyanate component (A) in the first coating composition and the polyisocyanate component (B) in the third coating composition were changed to the materials shown in Table 3. The second coating composition 2-3, which is mixed with the end-capped polyisocyanate component (D) described later, was used as the second coating composition. Otherwise, the sample coated plate having a 3-layer coating laminate was obtained by the same method as in Example 8.

[0730] (Preparation of the second coating composition 2-3 used in Example 23)

[0731] To water-based-2 (black) (product name: nax E-CUBE WB water-based color base (silent black), manufactured by NipponPaint Holdings Co., Ltd.), the above-prepared end-capped polyisocyanate component (D)-1 was added at a ratio of 4% by mass, and then deionized water was added at a ratio of 25% by mass of solids. The mixture was stirred at 600 rpm for 10 minutes using a propeller blade to obtain the second coating composition 2-3.

[0732] [Example 24]

[0733] (Preparation of sample coated plate T-a17)

[0734] The type of polyisocyanate component (A) in the first coating composition and the polyisocyanate component (B) in the third coating composition were changed to the materials shown in Table 3. The second coating composition 2-4, which is mixed with the end-capped polyisocyanate component (D) described later, was used as the second coating composition. Otherwise, the sample coated plate having a 3-layer coating laminate was obtained by the same method as in Example 8.

[0735] (Preparation of the terminated polyisocyanate component (D)-2 used in Example 24)

[0736] In a four-necked flask equipped with a thermometer, stirring blades, and a reflux condenser, 100 parts by mass of HDI and 5.2 parts by mass of a polyester polyol derived from trihydric alcohol and ε-caprolactone (manufactured by Dassault Chemicals, "Placcel 303" (trade name), average functional group number: 3, number average molecular weight 300) were added under a nitrogen atmosphere. The temperature inside the reactor was maintained at 88°C for 1 hour under stirring to carry out the carbamate reaction. The temperature inside the reactor was then maintained at 62°C, and a tetramethylammonium octanoate catalyst for isocyanurate esterification was added. Phosphoric acid was added to stop the reaction at a yield of 51% by mass. The reaction solution was filtered, and unreacted HDI was removed using a thin-film evaporator to obtain an isocyanurate-type polyisocyanate. The obtained polyisocyanate had an NCO content of 18.8% by mass, a number average molecular weight of 1180, and an average isocyanate base number of 5.3. Furthermore, the obtained polyisocyanate was subjected to further processing... 1 H-NMR analysis confirmed the presence of isocyanurate groups.

[0737] The polyisocyanate obtained above (100 parts by weight), dipropylene glycol dimethyl ether (DPDM) (13 parts by weight), methoxy polyethylene glycol (MPG-081, ethylene oxide repeating unit: 15, manufactured by Nippon Emulsifier Co., Ltd.) (representing 5 mol% of isocyanate groups per 100 mol% of polyisocyanate P-2), and 2-ethylhexyl phosphate (JP-508T, manufactured by Jōhoku Chemical Industry Co., Ltd.) (0.08 parts by weight) were mixed and stirred at 120°C for 2 hours to obtain a hydrophilic compound – modified polyisocyanate. The obtained polyisocyanate P-2 had an NCO content of 14.0% by weight and an average isocyanate group number of 5.0.

[0738] The hydrophilic compound-modified polyisocyanate obtained above was added in the following proportions: 100 parts by mass; diisopropyl malonate: 63.9 parts by mass (102 mol% relative to 100 mol% of NCO group); and dipropylene glycol dimethyl ether (DPDM) was further added to prepare the product with a solid content of 60% by mass. Next, while stirring, 1.0 part by mass of a methanol solution containing sodium methoxide (28% by mass relative to the total mass of the solution) was added dropwise. The external bath was adjusted to a solution temperature of 55°C, and the end-capping reaction was carried out at 55°C for 5 hours to obtain end-capped polyisocyanate component (D)-2 with a solid content of 60% by mass.

[0739] The specific structure and composition of the manufactured end-capped polyisocyanate component (D)-2 are shown in Table 3.

[0740] (Preparation of the second coating composition 2-4 used in Example 24)

[0741] To water-based-2 (black) (product name: nax E-CUBE WB water-based color base (silent black), manufactured by NipponPaint Holdings Co., Ltd.), the above-prepared end-capped polyisocyanate component (D)-2 was added at a ratio of 2% by mass, and then deionized water was added at a ratio of 25% by mass of solids. The mixture was stirred at 600 rpm for 10 minutes using a propeller blade to obtain the second coating composition 2-3.

[0742] Table 3

[0743]

[0744] [Comparative Example 4]

[0745] (Preparation of sample coated plate T-b2)

[0746] The coating composition described later was used as the first coating composition, and otherwise the sample coated plate was obtained using the same method as in Example 7.

[0747] (Preparation of the first coating composition used in Comparative Example 4)

[0748] Measure 87.9 parts of deionized water, 245.0 parts of titanium oxide pigment (English product name: Ti-Pure R-902+, Chemours), 17.2 parts of water-based wetting and dispersing agent (product name: BYK-190, BYK), and 0.7 parts of defoamer (product name: Tego902W) into a container and stir with a propeller blade at 2700 rpm for 120 minutes.

[0749] After stirring, add 650 parts of an acrylic polyol aqueous dispersion (product name: Setaqua 6510, hydroxyl value per unit resin: 138 mg KOH / g, manufactured by Allnex), and stir further at 1500 rpm for 30 minutes. While stirring, add 2.0 parts of a silicone defoamer (product name: BYK-024, manufactured by BYK), 0.7 parts of a defoamer (Tego902W), and 1.0 part of a surface conditioner (product name: BYK-346, manufactured by BYK), and stir for 15 minutes. Then, add 3.0 parts of a viscosity modifier (product name: Acrysol RM-8W, manufactured by Dow Chemical), and stir for 15 minutes.

[0750] Next, 146 parts of melamine resin (manufactured by Allnex Japan, product name "CYMEL 325", imino-methylated melamine resin) were added. Deionized water was added at a ratio of 43% by mass of the solids in the coating composition, and then 2-(dimethylamino)ethanol was added to achieve a pH of 8.0 for the coating composition. The mixture was stirred at 600 rpm for 10 minutes using a propeller blade to obtain coating composition 1-b2, which had a viscosity of 55 seconds as measured by Ford cup No. 4 at 20°C.

[0751] [evaluate]

[0752] (Coating hardness: Koenig)

[0753] The Koenegger hardness (in cycles) of the coated plates obtained in each example and comparative example was determined using an Erichsen pendulum hardness tester. The coating hardness was evaluated according to the following evaluation criteria: Koenegger.

[0754] (Evaluation Criteria)

[0755] 〇: More than 80 times

[0756] △: More than 60 times but less than 80 times

[0757] (Water resistance)

[0758] The sample coated plates obtained in each embodiment and comparative example were immersed in warm water at 40°C for 10 days, and after being taken out and dried, the following adhesion evaluation was performed.

[0759] On the coating surface of each test coated plate, 100 checkerboard patterns of 1mm × 1mm were made by scratching lines with a knife in a manner that reached the substrate. Transparent adhesive tape was attached to the surface of the checkerboard patterns. The number of residual coatings on the checkerboard patterns after they were suddenly peeled off at 23°C was investigated and evaluated according to the following criteria.

[0760] (Evaluation Criteria)

[0761] ◎: 100 pieces (without peeling)

[0762] 〇: More than 90 but less than 100

[0763] △: 50 or more but less than 90

[0764] ×: Less than 50

[0765] For each of the obtained coated samples, various physical properties were determined using the methods described above, and the hardness and water resistance of the coating were evaluated. The results are shown in Tables 4A and 4B.

[0766] (Final appearance)

[0767] The DOI (distinctness of image) of the coated plates obtained in each example and comparative example was determined using BYK WaveScan. The final appearance was evaluated according to the following evaluation criteria: DOI.

[0768] (Evaluation Criteria)

[0769] ◎:95 and above

[0770] ○: 90 and above, but below 94

[0771] △: 89 or less

[0772] Table 4A

[0773]

[0774] Table 4B

[0775]

[0776] As shown in the results above, when the substrate coating compositions of this embodiment in Examples 8 to 24 were cured at 80°C, multilayer coating laminates with good hardness and water resistance were also obtained.

[0777] The results of Comparative Examples 3 and 4 confirm that when the coating composition for the substrate does not meet the specific composition of the present invention, it cannot simultaneously achieve both hardness and water resistance when cured at 80°C.

Claims

1. A base paint composition which is a base paint composition for forming a multilayer coating film layered body on a coated object, the multilayer coating film layered body has a base layer and 1 or more coating films, the base paint composition contains a polyisocyanate component (A) and a hydroxyl group-containing resin component, the polyisocyanate component (A) contains a polyisocyanate having a sulfonate anion group in the molecule and one or more tertiary ammonium cations of an amine compound represented by the following general formula (1), In General Formula (1), R 11 , R 12 , and R 13 are each independently a hydrocarbon group having 1 to 10 carbons optionally containing an ether bond; at least one selected from the group consisting of R 11 , R 12 , and R 13 optionally contains a ring structure, two or more selected from the group consisting of R 11 , R 12 , and R 13 optionally bind to each other to form a ring structure; the ring structure is an aromatic ring, a cycloalkyl group having 5 or 6 carbons, a 5-membered ring or a 6-membered ring formed by R 11 binding to R 12 , or a polycyclic ring formed by R 11 binding to R 12 binding to R 13 binding to each other, the polyisocyanate component (A) contains an isocyanurate group represented by the following formula (I), an imino oxadiazinedione group represented by the following formula (II), and a uretdione group represented by the following formula (III), the specific molar ratio represented by the following formula (2) is 0.05 or more and 0.60 or less, Specific molar ratio = (B + C) / (A + B + C) (2) In formula (2), A represents the contained ratio of the isocyanurate group represented by the following formula (I) in terms of mol%, B represents the contained ratio of the imino oxadiazinedione group represented by the following formula (II) in terms of mol%, and C represents the contained ratio of the uretdione group represented by the following formula (III) in terms of mol%, 2. The coating composition for a substrate according to claim 1, wherein The isocyanate group in the polyisocyanate component (A) is contained in a ratio of 1.1 to 2.0 equivalents per 1 equivalent of the hydroxyl group in the hydroxyl group-containing resin component.

3. The coating composition for a substrate according to claim 1, wherein The isocyanate group in the polyisocyanate component (A) is contained in a ratio of 1.5 to 1.9 equivalents per 1 equivalent of the hydroxyl group in the hydroxyl group-containing resin component.

4. The coating composition for a substrate according to claim 1, wherein The polyisocyanate component (A) contains a uretdione dimer of a diisocyanate monomer and an isocyanurate trimer of a diisocyanate monomer.

5. The coating composition for a substrate according to claim 4, wherein The content of the uretdione dimer is 1.0 mass% or more and 20.0 mass% or less with respect to the total mass of the polyisocyanate component (A).

6. The coating composition for a substrate according to claim 1, wherein The specific molar ratio represented by the formula (2) is 0.08 or more and 0.50 or less.

7. The coating composition for a substrate according to claim 1, wherein The specific molar ratio represented by the formula (2) is 0.12 or more and 0.45 or less.

8. The coating composition for a substrate according to claim 1, wherein, The specific molar ratio represented by the formula (2) is 0.15 or more and 0.40 or less.

9. The coating composition for a substrate according to claim 1, wherein, The specific molar ratio represented by the formula (2) is 0.18 or more and 0.37 or less.

10. The coating composition for a substrate according to claim 1, wherein, The specific molar ratio represented by the formula (2) is 0.20 or more and 0.35 or less.

11. The coating composition for a substrate according to claim 1, wherein The polyisocyanate having a sulfonate anion group in the molecule is a reaction product of an amine salt of a sulfonic acid having a reactive hydrogen group and a polyisocyanate, The amine salt of the sulfonic acid having a reactive hydrogen group is a salt of a sulfonic acid having a reactive hydrogen group and the amine compound represented by the general formula (1).

12. The coating composition for a substrate according to claim 1 or 4, wherein, The polyisocyanate component (A) is an aliphatic polyisocyanate.

13. A multilayer coating film layered body which is a multilayer coating film layered body in which a first coating film, a second coating film, and a third coating film are layered in this order, the first coating film is formed from the base paint composition according to claim 1 or 4, the second coating film is formed from a paint composition containing a hydroxyl group-containing resin component, the third coating film is formed from a two-component type paint composition containing a hydroxyl group-containing resin component and a polyisocyanate component.

14. The multilayer coated film stack of claim 13, wherein, the second coating film is formed from a hydroxyl group-containing resin component and a blocked polyisocyanate component (D).

15. The multilayer coated film stack of claim 14, wherein, The capped polyisocyanate component (D) contains a structural unit (I) represented by the following general formula (I), In General Formula (I), R 11 , R 12 , and R 13 are each independently an alkyl group optionally containing one or more substituents selected from the group consisting of a hydroxyl group and an amino group, the total carbon number of R 11 , R 12 , and R 13 is 4 or more and 20 or less, R 14 , R 15 , and R 16 are each independently a hydrogen atom or an alkyl group optionally containing one or more substituents selected from the group consisting of a hydroxyl group and an amino group, and the wavy line indicates a bonding site to a residue resulting from removal of an isocyanate group from a polyisocyanate.

16. The multilayer coated film stack of claim 15, wherein, R 11 , R 12 , R 13 , R 14 , R 15 , and R 16 are each independently an unsubstituted alkyl group having 1 or more and 4 or less carbon atoms.

17. The multilayer coated film stack of claim 15, wherein, R 14 , R 15 , and at least one of R 16 is a hydrogen atom.

18. The multilayer coated film stack of claim 15, wherein, The capped polyisocyanate component (D) further contains a structural unit represented by the following general formula (II), In General Formula (II), R 21 , R 22 , R 23 , and R 24 are each independently a hydrogen atom, or an alkyl group optionally containing one or more substituents selected from the group consisting of a hydroxyl group and an amino group, and the wavy line indicates a bonding site with a residue resulting from removal of an isocyanate group from a polyisocyanate.

19. The multilayer coated film stack of claim 18, wherein, R 21 , R 22 , R 23 and R 24 are each independently methyl or ethyl.

20. The multilayer coated film stack of claim 18, wherein, The molar ratio of the structural unit (II) to the structural unit (I) represented by the general formula (II) is 4 / 96 or more and 96 / 4 or less.

21. A method for forming a multilayer coating film laminate, comprising the following steps: a step of applying a first coating material composition on a coated object to obtain a first uncured coating film; a step of applying a second coating material composition on the first uncured coating film to obtain a second uncured coating film; a step of applying a third coating material composition on the second uncured coating film to obtain a third uncured coating film; and a step of simultaneously curing the first uncured coating film, the second uncured coating film, and the third uncured coating film by heating at 40°C or higher and 140°C or lower to form a multilayer coating film laminate comprising three layers of a first coating film, a second coating film, and a third coating film, the first coating material composition is the base coating material composition according to claim 1 or 4, the second coating material composition is a coating material composition containing a hydroxyl group-containing resin component, the third coating material composition is a two-component type coating material composition containing a hydroxyl group-containing resin component and a polyisocyanate component.

22. The method for forming a multilayer coated film laminate according to claim 21, wherein, The second coating material composition is a coating material composition containing a hydroxyl group-containing resin component and a capped polyisocyanate component (D).

23. The multi-layer coated film stack of claim 22, wherein, The content of the capped polyisocyanate component (D) in the second coating material composition is 0.5% by mass or more and 20% by mass or less with respect to the total mass of the second coating material composition.

24. The method for forming a multilayer coated film laminate according to claim 22, wherein, The capped polyisocyanate contained in the capped polyisocyanate component (D) contains a structural unit (I) represented by the following general formula (I), The capped polyisocyanate contained in the capped polyisocyanate component (D) contains a structural unit (I) represented by the following general formula (I), In General Formula (I), R 11 , R 12 , and R 13 are each independently an alkyl group optionally containing one or more substituents selected from the group consisting of a hydroxyl group and an amino group, the total carbon number of R 11 , R 12 , and R 13 is 4 or more and 20 or less, R 14 , R 15 , and R 16 are each independently a hydrogen atom or an alkyl group optionally containing one or more substituents selected from the group consisting of a hydroxyl group and an amino group, and the wavy line indicates a bonding site to a residue resulting from removal of an isocyanate group from a polyisocyanate.

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