Undercoat paint composition, coating paint composition, coated film laminate, and method for producing coated film laminate

Abstract

To provide an undercoat paint composition and a coating paint composition that are capable of producing a coated film laminate having excellent hardness and water resistance, even when cured at a low temperature.SOLUTION: An undercoat paint composition for forming a coated film laminate on an object to be coated comprises a blocked polyisocyanate component and a hydroxyl group-containing resin component. The blocked polyisocyanate component comprises a blocked polyisocyanate derived from a polyisocyanate and one or more blocking agents. The blocked polyisocyanate component includes a structural unit represented by the general formula (I).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an undercoat paint composition, a coating paint composition, a coating film laminate, and a method for producing the coating film laminate.

Background Art

[0002] In recent years, for example, the use of aqueous paint compositions as undercoat paints used for automobile exterior panels and interior panels has been increasing. Since this aqueous paint composition contains almost no organic solvent, it is suitable from the viewpoint of preventing environmental pollution.

[0003] For example, Patent Document 1 discloses an aqueous paint composition combining an aqueous base polyol and a specific melamine.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] On the other hand, in addition to the viewpoint of global environmental protection, there is a strong demand for a paint composition that can also be used for plastics with low heat resistance. A paint composition that can be used for plastics with low heat resistance means a paint composition that exhibits coating film performance even at a low curing temperature. However, in the technique disclosed in Patent Document 1, when the curing temperature is low, the chipping resistance and coating film hardness of the coating film laminate may be insufficient.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide an undercoat paint composition and a coating paint composition that can produce a coating film laminate excellent in hardness and water resistance even when cured at a low temperature, a coating film laminate using the undercoat paint composition and the coating paint composition, and a method for producing the coating film laminate. In this specification, "curing at low temperature" means curing in a temperature range of 40°C or higher and 140°C or lower.

Means for Solving the Problems

[0007] That is, the present invention includes the following aspects. [1] A base paint composition for forming a coating laminate on an object to be coated, wherein the base paint composition contains a blocked polyisocyanate component and a hydroxyl group-containing resin component, the blocked polyisocyanate component contains a blocked polyisocyanate derived from a polyisocyanate and one or more blocking agents, and the blocked polyisocyanate component contains a structural unit represented by the following general formula (I).

Chemical formula

[0008] According to the present invention, it is possible to provide an undercoat paint composition and a coating paint composition capable of producing a coating film laminate excellent in hardness and water resistance even when cured at a low temperature, a coating film laminate using the undercoat paint composition and the coating paint composition, and a method for producing the coating film laminate.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0010] Hereinafter, embodiments for carrying out the present invention (hereinafter, may be simply referred to as "the present embodiment") will be described in detail. The following present embodiment is an exemplification for explaining the present invention and is not intended to limit the present invention to the following contents. The present invention can be appropriately modified and implemented within the scope of its gist.

[0011] In this specification, "polyisocyanate" means a polymer in which a plurality of monomers having two or more isocyanate groups (-NCO) are bonded. In this specification, "polyol" means a compound having two or more hydroxy groups (-OH).

[0012] <Undercoat paint composition> The present embodiment is an undercoat paint composition for forming a coating film laminate on an object to be coated. More specifically, the undercoat composition of the present embodiment is a material for forming an underlayer in contact with the object to be coated when forming a coating film laminate on the object to be coated. In one aspect of the present invention, the underlayer is a layer directly in contact with the object to be coated.

[0013] By forming an undercoat layer on an object to be coated using the undercoat composition of the present embodiment and further laminating a coating film on the undercoat layer, a coating film laminate excellent in hardness and water resistance can be produced even when cured at a low temperature.

[0014] The undercoat paint composition of the present embodiment contains a blocked polyisocyanate component and a hydroxyl group-containing resin component. Hereinafter, the blocked polyisocyanate component may be referred to as the "BPI component". By satisfying a specific composition, the undercoat paint composition of the present embodiment has good dispersion stability, and it becomes difficult for isocyanate groups and water to react, so the pot life is improved. Note that the dispersion stability means a state in which the dispersed state hardly changes over time and separation such as sedimentation hardly occurs even after the passage of time. The constituent components of the undercoat paint composition of the present embodiment will be described in detail.

[0015] ≪BPI component≫ The BPI component used in the undercoat paint composition of the present embodiment contains a blocked polyisocyanate derived from a polyisocyanate and one or more blocking agents. The BPI component contains a structural unit represented by the following general formula (I).

[0016]

Chemical formula

[0017] In the general formula (I), R 11 , R 12 and R 13 are each independently an alkyl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group, and the total number of carbon atoms of R 11 , R 12 and R 13 is 4 or more and 20 or less, and R 14 , R 15 and R 16 are each independently a hydrogen atom or an alkyl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group, and the wavy line represents the bonding site with the residue excluding the isocyanate group of the polyisocyanate.

[0018] R 11 , R 12 , R 13 , R 14 , R 15 and R 16 The alkyl group in is preferably having 1 to 20 carbon atoms, more preferably 1 to 8 carbon atoms, still more preferably 1 to 6 carbon atoms, and particularly preferably 1 to 4 carbon atoms.

[0019] Specific examples of the alkyl group having no substituent include, for example, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, tert-butyl group, sec-butyl group, isobutyl group, n-pentyl group, isopentyl group, neopentyl group, tert-pentyl group, 1-methylbutyl group, n-hexyl group, 2-methylpentyl group, 3-methylpentyl group, 2,2-dimethylbutyl group, 2,3-dimethylbutyl group, n-heptyl group, 2-methylhexyl group, 3-methylhexyl group, 2,2-dimethylpentyl group, 2,3-dimethylpentyl group, 2,4-dimethylpentyl group, 3,3-dimethylpentyl group, 3-ethylpentyl group, 2,2,3-trimethylbutyl group, n-octyl group, isooctyl group, 2-ethylhexyl group, nonyl group, decyl group and the like.

[0020] Also, R 11 , R12 and R 13 and R 14 and R 15 and R 16 When R, R, R, and R are alkyl groups having substituents, the substituents are hydroxy groups or amino groups. Examples of the alkyl group containing a hydroxy group as a substituent include a hydroxymethyl group, a hydroxyethyl group, and a hydroxypropyl group. Examples of the alkyl group containing an amino group as a substituent include an aminomethyl group, an aminoethyl group, an aminopropyl group, and an aminobutyl group. Examples of the alkyl group containing a hydroxy group and an amino group as substituents include a hydroxyaminomethyl group, a hydroxyaminoethyl group, and a hydroxyaminopropyl group. Among them, since the storage stability when used as a paint composition and the low-temperature curability when used as a resin film are further improved, R, R, and R are preferably each independently an unsubstituted alkyl group having 1 to 4 carbon atoms, more preferably a methyl group or an ethyl group, and preferably at least one of them is an ethyl group. 11 and R 12 and R 13 The total carbon number of R, R, and R is preferably from 4 to 20, more preferably from 4 to 12, still more preferably from 4 to 9, and still more preferably from 4 to 6.

[0021] R 11 and R 12 and R 13 By having the total carbon number of R, R, and R be at least the above lower limit value, the storage stability when used as an aqueous paint composition can be exhibited. On the other hand, by being at most the above upper limit value, the low-temperature curability can be exhibited. Also, from the viewpoint of improving the solvent resistance of the coating film, the total carbon number of R, R, and R is more preferably 4. R 11 and R 12 and R 13 and R 11 and R 12 and R 13 The total carbon number of R, R, and R is more preferably 4.

[0022] R11 , R 12 and R 13 The total carbon number of is, if the total carbon number is within the above range, R 11 , R 12 and R 13 The carbon number of each of is not limited.

[0023] Also, R 14 , R 15 and R 16 are each independently an alkyl group which may contain one or more substituents selected from the group consisting of a hydrogen atom, a hydroxy group and an amino group, preferably an unsubstituted alkyl group having 1 to 4 carbon atoms. Among them, it is preferable that at least one of R 14 , R 15 and R 16 is a hydrogen atom, and more preferably only one is a hydrogen atom. Among R 14 , R 15 and R 16 , by at least one of them being a hydrogen atom, it is possible to further improve the storage stability when it is made into an aqueous resin composition while maintaining the low-temperature curability. That is, as the structural unit (I), it is more preferable to contain a structural unit represented by the following general formula (I-1) (hereinafter, may be referred to as the structural unit (I-1)).

[0024] [Chemical formula]

[0025] In the general formula (I-1), R 11 , R 12 , R 13 , R 14 and R 15 are as described in the general formula (I). The wavy line represents the bonding site with the residue excluding the isocyanate group of the polyisocyanate.

[0026] As the molar ratio of the structural unit (I-1) in the structural unit (I) (structural unit (I-1) / structural unit (I)), 10 mol% or more is more preferable, more preferably 30 mol% or more, even more preferably 50 mol% or more, even more preferably 80 mol% or more, and even more preferably 90 mol% or more.

[0027] [Structural unit (II)] In the molecule of the BPI component, it is preferable to further contain a structural unit represented by the following general formula (II) (hereinafter sometimes referred to as the structural unit (II)).

[0028]

Chemical formula

[0029] In the general formula (II), R 21 , R 22 , R 23 and R 24 are each independently a hydrogen atom or an alkyl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group, and the wavy line represents the bonding site with the residue obtained by removing the isocyanate group of the polyisocyanate. R 21 , R 22 , R 23 and R 24 Examples of the alkyl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group in R 11 , R 12 , R 13 , R 14 , R 15 and R 16 are the same as those exemplified in the above "R

[0030] Among them, R 21 , R 22 , R 23 and R 24As the alkyl group, a hydrogen atom or an alkyl group having no substituent and having 1 to 4 carbon atoms is preferable because they have excellent storage stability when made into an aqueous resin composition, a hydrogen atom, a methyl group, or an ethyl group is more preferable, and a methyl group or an ethyl group is even more preferable because they have excellent low-temperature curing properties.

[0031] R 21 , R 22 , R 23 and R 24 When all of R are methyl groups, the two ester moieties of the malonic acid ester of the structural unit (II) are both isopropyl groups. 21 and R 22 one of the groups is a hydrogen atom and the other is a methyl group, and R 23 and R 24 When one of R is a hydrogen atom and the other is a methyl group, the two ester moieties of the malonic acid ester of the structural unit (II) are both ethyl groups. 21 , R 22 , R 23 and R 24 are all methyl groups, that is, the two ester moieties of the malonic acid ester of the structural unit (II) are both isopropyl groups.

[0032] The molar ratio of the structural unit represented by the general formula (II) to the structural unit represented by the general formula (I) (structural unit (II) / structural unit (I)) is preferably 4 / 96 or more and 96 / 4 or less, more preferably 5 / 95 or more and 95 / 5 or less, even more preferably 7 / 93 or more and 93 / 7 or less, even more preferably 10 / 90 or more and 90 / 10 or less, even more preferably 20 / 80 or more and 85 / 15 or less, even more preferably 30 / 70 or more and 85 / 15 or less, even more preferably 35 / 65 or more and 85 / 15 or less, and even more preferably 50 / 50 or more and 70 / 30 or less. By having the molar ratio be equal to or more than the lower limit, the storage stability when made into a resin composition can be improved, and by having the molar ratio be equal to or less than the upper limit, the low-temperature curing property when made into a resin film can be improved.

[0033] The molar ratio can be determined, for example, by measuring the composition ratio of the structural unit (II) to the structural unit (I) in the coating composition 1 by 1H-NMR and 13 13C-NMR, and calculating the molar ratio of the structural unit (II) to the structural unit (I).

[0034] In the general formula (I), it is preferable that R 11 , R 12 and R 13 are all methyl. Although it is known that a BPI component in which at least one ester group in the diester moiety is a tert-butyl group has excellent curability with a polyhydroxy compound at a low temperature of about 85°C, in an aqueous coating composition, it has a high reactivity with water. When it is blended in an aqueous coating composition and stored as an aqueous coating composition containing a polyhydroxy compound, a curing agent, and water, there is a tendency for the viscosity to increase or gelation to occur easily.

[0035] When the total carbon number of R 11 , R 12 and R 13 in the structural unit (I) is 4 or more and 20 or less, even when blended in an aqueous coating composition, it can effectively suppress the increase in viscosity and gelation during storage of the mixture of the polyhydroxy compound, the curing agent, and water, and exhibit good storage stability. At the same time, a resin film excellent in curability at a low temperature of about 85°C can be obtained.

[0036] In the molecule of the blocked polyisocyanate contained in the BPI component, at least some of the isocyanate groups may be blocked with a malonic acid ester having a secondary alkyl group or a malonic acid ester having a primary alkyl group, and a malonic acid ester having a tertiary alkyl group. Alternatively, it may be a blocked polyisocyanate in which at least some of the isocyanate groups in the polyisocyanate are blocked with a malonic acid ester having a secondary alkyl group, or a blocked polyisocyanate in which at least some of the isocyanate groups in the polyisocyanate are blocked with a malonic acid ester having a primary alkyl group, and a mixture of blocked polyisocyanates in which at least some of the isocyanate groups in the polyisocyanate are blocked with a malonic acid ester having a tertiary alkyl group.

[0037] [Other functional groups] The BPI component can have one or more functional groups selected from the group consisting of allophanate groups, uretdione groups, iminooxadiazinedione groups, isocyanurate groups, urethane groups and biuret groups. Among them, it preferably has an isocyanurate group because of its excellent weather resistance.

[0038] [Polyisocyanate] (Isocyanate) The polyisocyanate used in the production of the BPI component is a reaction product obtained by reacting a plurality of monomer compounds having one or more isocyanate groups (-NCO) (hereinafter sometimes referred to as "isocyanate monomer").

[0039] The isocyanate monomer preferably has 4 to 30 carbon atoms. Specifically, examples of the isocyanate monomer include the following. These isocyanate monomers may be used alone or in combination of two or more.

[0040] (1) Aromatic diisocyanates such as diphenylmethane-4,4'-diisocyanate (MDI), 1,5-naphthalene diisocyanate, tolylene diisocyanate (TDI), xylylene diisocyanate, m-tetramethylxylylene diisocyanate (TMXDI). (2) Aliphatic diisocyanates such as 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (hereinafter sometimes referred to as "HDI"), 2,2,4-trimethyl-1,6-diisocyanatohexane, 2,4,4-trimethyl-1,6-hexamethylene diisocyanate, 2-methylpentane-1,5-diisocyanate (MPDI), lysine diisocyanate (hereinafter sometimes referred to as "LDI").

[0041] (3) Alicyclic diisocyanates such as isophorone diisocyanate (hereinafter sometimes referred to as "IPDI"), 1,3-bis(diisocyanatomethyl) cyclohexane, 4,4'-dicyclohexylmethane diisocyanate, diisocyanato norbornane, di(isocyanatomethyl) norbornane. (4) Triisocyanates such as 4-isocyanatomethyl-1,8-octamethylene diisocyanate (hereinafter sometimes referred to as "NTI"), 1,3,6-hexamethylene triisocyanate (hereinafter sometimes referred to as "HTI"), bis(2-isocyanatoethyl) 2-isocyanatoglutarate (hereinafter sometimes referred to as "GTI"), lysine triisocyanate (hereinafter sometimes referred to as "LTI").

[0042] As the isocyanate monomer used in the production of polyisocyanate, one or more diisocyanates selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates are preferred because of their excellent weather resistance. Further, diisocyanate monomers other than the above-described aliphatic diisocyanates and alicyclic diisocyanates may be further used. Further, as the isocyanate monomer, HDI or IPDI is more preferable from the viewpoint of easy industrial availability. Further, as the isocyanate monomer, HDI is even more preferable from the viewpoint of reducing the viscosity of the blocked polyisocyanate component.

[0043] The polyisocyanate preferably has an isocyanurate group, and in addition to the isocyanurate group, it can have one or more functional groups selected from the group consisting of allophanate group, uretdione group, iminooxadiazinedione group, isocyanurate group, urethane group and biuret group.

[0044] (Polyol) The polyisocyanate used in the production of the BPI component is preferably derived from the above-described diisocyanate and a polyol having an average functionality of 3.0 or more and 8.0 or less. Thereby, the average isocyanate group number of the polyisocyanate can be made larger. In the polyisocyanate, a urethane group is formed by the reaction of the hydroxyl group of the polyol and the isocyanate group of the diisocyanate monomer.

[0045] The average functionality of the polyol used in the production of the BPI component 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. Here, the average functionality of the polyol refers to the number of hydroxyl groups present in one molecule of the polyol.

[0046] The number average molecular weight of the polyol used in the production of the BPI component is preferably 100 or more and 1000 or less, more preferably 100 or more and 900 or less, still more preferably 100 or more and 600 or less, even more preferably 100 or more and 570 or less, further preferably 100 or more and 500 or less, even further 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, from the viewpoints of improving the coating film hardness and strength. When the number average molecular weight of the polyol is within the above range, the base coating composition is excellent in low-temperature curability when formed into a coating film, and particularly excellent in hardness and strength. The number average molecular weight Mn of the polyol is, for example, the number average molecular weight based on polystyrene measured by GPC measurement.

[0047] Examples of such polyols include trimethylolpropane, glycerol, and polycaprolactone polyols derived from trivalent or higher polyhydric alcohols and ε-caprolactone. Examples of commercially available polycaprolactone polyols include "Placcel 303" (number average molecular weight 300), "Placcel 305" (number average molecular weight 550), "Placcel 308" (number average molecular weight 850), "Placcel 309" (number average molecular weight 900), etc. of Daicel Corporation.

[0048] (Production of Polyisocyanate) The production method of the polyisocyanate used in the production of the BPI component will be described in detail below. Polyisocyanates can be obtained, for example, by simultaneously carrying out an allophanatization reaction to form allophanate groups, a uretdione formation reaction to form uretdione groups, an iminooxadiazinedione formation reaction to form iminooxadiazinedione groups, an isocyanuration reaction to form isocyanurate groups, a urethanization reaction to form urethane groups, and a biuret formation reaction in the presence of an excess of isocyanate monomer, and then removing the unreacted isocyanate monomer after completion of the reaction. That is, the polyisocyanate obtained by the above reaction is a compound in which a plurality of the above-mentioned isocyanate monomers are bonded, and is a reaction product having at least one selected from the group consisting of allophanate groups, uretdione groups, iminooxadiazinedione groups, isocyanurate groups, urethane groups, and biuret groups. Alternatively, the above reactions may be carried out separately, and the polyisocyanates obtained respectively may be mixed at a specific ratio. From the viewpoint of ease of production, it is preferable to carry out the above reaction once to obtain a polyisocyanate, and from the viewpoint of freely adjusting the molar ratio of each functional group, it is preferable to mix them after producing them separately.

[0049] In addition, for the obtained polyisocyanate, for example, an antioxidant or an ultraviolet absorber may be added for the purpose of suppressing coloring during storage. Examples of the antioxidant include hindered phenols such as 2,6-di-tert-butyl-p-cresol. Examples of the ultraviolet absorber include benzotriazole and benzophenone. These antioxidants and ultraviolet absorbers may be used alone or in combination of two or more. The addition amount thereof is preferably 10 mass ppm or more and 500 mass ppm or less based on the mass of the polyisocyanate.

[0050] (Average number of isocyanate groups of polyisocyanate) From the perspective of enhancing the low-temperature curability when forming a coating film laminate, the average isocyanate functionality of the polyisocyanate used in the production of the BPI component is preferably 3 or more, more preferably 3.2 or more, still more preferably 3.5 or more, and particularly preferably 4.0 or more. Also, from the perspective of achieving both the low-temperature curability when forming a coating film laminate and compatibility with the polyhydric hydroxy compound, it is more preferably 3 or more and 20 or less, still more preferably 3.2 or more and 10 or less, particularly preferably 3.5 or more and 8 or less, and most preferably 4.0 or more and 6 or less.

[0051] The average isocyanate functionality of the polyisocyanate can be determined, for example, using the following formula from the number average molecular weight Mn and the isocyanate group content (NCO content) of the polyisocyanate. Average isocyanate functionality = (Mn of polyisocyanate × NCO content × 0.01) / 42

[0052] [Blocking agent] The blocking agent used in the production of the BPI component preferably includes a malonic acid ester having a secondary alkyl group or a malonic acid ester having a primary alkyl group, and a malonic acid ester having a tertiary alkyl group, and more preferably includes a malonic acid ester having a secondary alkyl group and a malonic acid ester having a tertiary alkyl group. The blocking agent may contain one kind each of a malonic acid ester having a secondary alkyl group, a malonic acid ester having a primary alkyl group, and a malonic acid ester having a tertiary alkyl group, or may contain two or more kinds in combination. Examples of the malonic acid ester having a primary alkyl group are not particularly limited, and include, for example, dimethyl malonate, diethyl malonate, dipropyl malonate, dibutyl malonate, dicyclohexyl malonate, diphenyl malonate, etc. Among them, diethyl malonate is preferred as the malonic acid ester having a primary alkyl group.

[0053] The malonic acid ester having a secondary alkyl group is not particularly limited, and examples thereof include di-sec-butyl malonate, diisopropyl malonate, isopropyl ethyl malonate, and the like. Among them, diisopropyl malonate is preferable as the malonic acid ester having a secondary alkyl group.

[0054] The malonic acid ester having a tertiary alkyl group is not particularly limited, and examples thereof include di-tert-butyl malonate, di(2-methyl-2-butyl) malonate, di(2-methyl-2-pentyl) malonate, (tert-butyl) ethyl malonate, (2-methyl-2-butyl) ethyl malonate, (2-methyl-2-butyl) isopropyl malonate, (2-methyl-2-pentyl) ethyl malonate, (2-methyl-2-pentyl) isopropyl malonate, (2-methyl-2-pentyl) hexyl isopropyl malonate, and the like. Among them, di(2-methyl-2-butyl) malonate, di(2-methyl-2-pentyl) malonate, (2-methyl-2-butyl) isopropyl malonate, (2-methyl-2-pentyl) ethyl malonate, and (2-methyl-2-pentyl) isopropyl malonate are preferable, (2-methyl-2-butyl) ethyl malonate, (2-methyl-2-butyl) isopropyl malonate, (2-methyl-2-pentyl) ethyl malonate, and (2-methyl-2-pentyl) hexyl isopropyl malonate are preferable, or di-tert-butyl malonate, (2-methyl-2-butyl) isopropyl malonate, or (2-methyl-2-pentyl) isopropyl malonate is preferable. As the malonic acid ester having a tertiary alkyl group, a commercially available product may be used, or a product synthesized using the method of Reference 1 (Japanese Patent Laid-Open No. 11-130728) may be used.

[0055] (Other blocking agents) In addition to the malonic acid ester having a secondary alkyl group and the malonic acid ester having a tertiary alkyl group, the blocking agent used in the production of the BPI component may further contain other blocking agents as long as the storage stability when formed into a resin composition and the low-temperature curability when formed into a resin film are not impaired.

[0056] Examples of other blocking agents include, for example, 1) alcohol-based compounds, 2) alkylphenol-based compounds, 3) phenol-based compounds, 4) active methylene-based compounds other than malonic esters having a secondary alkyl group and malonic esters having a tertiary alkyl group, 5) mercaptan-based compounds, 6) acid amide-based compounds, 7) acid imide-based compounds, 8) imidazole-based compounds, 9) urea-based compounds, 10) oxime-based compounds, 11) amine-based compounds, 12) imide-based compounds, 13) bisulfites, 14) pyrazole-based compounds, 15) triazole-based compounds, and the like. More specifically, examples of the blocking agent include those shown below.

[0057] 1) Alcohol-based compounds: Alcohols such as methanol, ethanol, 2-propanol, n-butanol, sec-butanol, 2-ethyl-1-hexanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol. 2) Alkylphenol-based compounds: Mono- and dialkylphenols having an alkyl group with 4 or more carbon atoms as a substituent. Specifically, examples of the alkylphenol-based compounds include, for example, monoalkylphenols such as n-propylphenol, iso-propylphenol, n-butylphenol, sec-butylphenol, tert-butylphenol, n-hexylphenol, 2-ethylhexylphenol, n-octylphenol, n-nonylphenol; dialkylphenols such as di-n-propylphenol, diisopropylphenol, isopropylcresol, di-n-butylphenol, di-tert-butylphenol, di-sec-butylphenol, di-n-octylphenol, di-2-ethylhexylphenol, di-n-nonylphenol. 3) Phenol-based compounds: Phenol, cresol, ethylphenol, styrenated phenol, hydroxybenzoic acid ester, etc. 4) Active methylene-based compounds: Dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate, methyl isobutanoylacetate, ethyl isobutanoylacetate, acetylacetone, etc. 5) Mercaptan compounds: butyl mercaptan, dodecyl mercaptan, etc. 6) Acid amide compounds: acetanilide, acetic acid amide, ε-caprolactam, δ-valerolactam, γ-butyrolactam, etc. 7) Acid imide compounds: succinimide, maleimide, etc. 8) Imidazole compounds: imidazole, 2-methylimidazole, etc. 9) Urea compounds: urea, thiourea, ethylene urea, etc. 10) Oxime compounds: formaldehyde oxime, acetaldehyde oxime, acetoxime, methyl ethyl ketoxime, cyclohexanone oxime, etc. 11) Amine compounds: diphenylamine, aniline, carbazole, di-n-propylamine, diisopropylamine, isopropylethylamine, etc. 12) Imine compounds: ethyleneimine, polyethyleneimine, etc. 13) Bisulfite compounds: sodium bisulfite, etc. 14) Pyrazole compounds: pyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole, etc. 15) Triazole compounds: 3,5-dimethyl-1,2,4-triazole, etc.

[0058] [Hydrophilic compounds] The blocked polyisocyanate contained in the BPI component may have a part of the isocyanate groups modified with a hydrophilic compound. That is, the blocked polyisocyanate may have a structural unit derived from a hydrophilic compound introduced into a part of the isocyanate groups.

[0059] The hydrophilic compound is a compound having a hydrophilic group. The hydrophilic compound preferably has, per molecule of the hydrophilic compound, one or more active hydrogen groups for reacting with at least one of the isocyanate groups that the polyisocyanate has, in addition to the hydrophilic group. Specific examples of the active hydrogen group include a hydroxyl group, a mercapto group, a carboxylic acid group, an amino group, and a thiol group.

[0060] Examples of the hydrophilic compound include nonionic compounds, cationic compounds, and anionic compounds. These hydrophilic compounds may be used alone or in combination of two or more. Among them, from the viewpoints of easy availability and low susceptibility to electrical interaction with the formulation, nonionic compounds are preferred as the hydrophilic compound, and anionic compounds are preferred from the viewpoint of suppressing a decrease in the hardness of the resulting resin film.

[0061] (Nonionic compound) Specific examples of the nonionic compound contained in the BPI component include monoalcohols and compounds obtained by adding ethylene oxide to the hydroxyl group of an alcohol. Examples of the monoalcohol include methanol, ethanol, butanol, and the like. Examples of the compound obtained by adding ethylene oxide to the hydroxyl group of an alcohol include ethylene glycol, diethylene glycol, polyethylene glycol, and the like. These nonionic compounds also have an active hydrogen group that reacts with an isocyanate group. Among them, as the nonionic compound contained in the blocked polyisocyanate component, polyethylene glycol monoalkyl ether obtained by adding ethylene oxide to the hydroxyl group of a monoalcohol is preferred because the water dispersibility of the primer coating composition can be improved with a small amount of use.

[0062] The number of added moles of ethylene oxide in the compound to which ethylene oxide is added is preferably 4 or more and 30 or less, more preferably 4 or more and 25 or less. When the number of added moles of ethylene oxide is at least the above lower limit value, the water dispersibility can be more effectively imparted to the primer coating composition, and when the number of added moles of ethylene oxide is at most the above upper limit value, deposits of the primer coating composition are less likely to occur during low-temperature storage.

[0063] The lower limit of the amount of the structural unit derived from the nonionic compound added to the BPI component (hereinafter sometimes referred to as the "content of the nonionic compound") is preferably 0.1% by mass, more preferably 0.15% by mass, still more preferably 0.2% by mass, and particularly preferably 0.25% by mass, based on the mass of the solid content of the base coating composition, from the viewpoint of the water dispersion stability of the base coating composition.

[0064] On the other hand, the upper limit of the content of the nonionic compound is preferably 55% by mass, more preferably 50% by mass, still more preferably 48% by mass, and particularly preferably 44% by mass, based on the mass of the solid content of the base coating composition, from the viewpoint of the water resistance of the resulting resin film. That is, the content of the nonionic compound is preferably 0.1% by mass or more and 55% by mass or less, more preferably 0.15% by mass or more and 50% by mass or less, still more preferably 0.20% by mass or more and 48% by mass or less, and particularly preferably 0.25% by mass or more and 44% by mass or less, based on the mass of the solid content of the base coating composition. When the content of the nonionic compound is within the above range, the base coating composition tends to disperse more in water and a homogeneous film can be obtained.

[0065] From the viewpoint of suppressing a decrease in the hardness and strength of the resulting resin film, when the amount of the nonionic compound added to the blocked polyisocyanate is expressed as a molar ratio, it is preferably 0.05 mol% or more and 15 mol% or less, more preferably 0.10 mol% or more and 12 mol% or less, still more preferably 0.10 mol% or more and 9 mol% or less, further preferably 0.10 mol% or more and 6 mol% or less, and most preferably 0.15 mol% or more and 4 mol% or less, based on 100 mol% of the isocyanate groups of the raw material polyisocyanate.

[0066] (Cationic compound) As the cationic compound contained in the BPI component, specifically, compounds having both a cationic hydrophilic group and an active hydrogen group can be mentioned. Further, a compound having an active hydrogen group such as a glycidyl group and a compound having a cationic hydrophilic group such as a sulfide or a phosphine may be combined as a hydrophilic compound. In this case, a compound having an isocyanate group and a compound having an active hydrogen group are reacted in advance to add a functional group such as a glycidyl group, and then a compound such as a sulfide or a phosphine is reacted. From the viewpoint of ease of production, a compound having both a cationic hydrophilic group and an active hydrogen group is preferable.

[0067] As the compound having both a cationic hydrophilic group and an active hydrogen group, specifically, for example, dimethylethanolamine, diethylethanolamine, diethanolamine, methyldiethanolamine, etc. can be mentioned. Further, the tertiary amino group added using these compounds can also be quaternized with, for example, dimethyl sulfate or diethyl sulfate.

[0068] The reaction between the cationic compound and the alicyclic polyisocyanate can be carried out in the presence of a solvent. In this case, the solvent preferably does not contain an active hydrogen group, and specifically, for example, ethyl acetate, propylene glycol monomethyl ether acetate, dipropylene glycol dimethyl ether, etc. can be mentioned.

[0069] The cationic hydrophilic group added to the blocked polyisocyanate is preferably neutralized with a compound having an anionic group. As this anionic group, specifically, for example, a carboxy group, a sulfonic acid group, a phosphoric acid group, a halogen group, a sulfuric acid group, etc. can be mentioned. As the compound having a carboxy group, specifically, for example, formic acid, acetic acid, propionic acid, butyric acid, lactic acid, etc. can be mentioned. As the compound having a sulfonic acid group, specifically, for example, ethanesulfonic acid, etc. can be mentioned. As the compound having a phosphoric acid group, specifically, for example, phosphoric acid, acidic phosphate ester, etc. can be mentioned. Examples of the compound having a halogen group include, specifically, hydrochloric acid and the like. Examples of the compound having a sulfate group include, specifically, sulfuric acid and the like. Among them, as the compound having an anionic group, a compound having a carboxy group is preferable, and acetic acid, propionic acid or butyric acid is more preferable.

[0070] (Anionic compound) Specific examples of the anionic hydrophilic group contained in the BPI component include a carboxy group, a sulfonic acid group, a phosphoric acid group, a halogen group, and a sulfate group. Examples of the anionic compound include a compound having both an anionic group and an active hydrogen group. More specifically, for example, compounds having a carboxy group of monohydroxycarboxylic acid or polyhydroxycarboxylic acid as an anionic group can be mentioned. Examples of the monohydroxycarboxylic acid include 1-hydroxyacetic acid, 3-hydroxypropanoic acid, 12-hydroxy-9-octadecenoic acid, hydroxypivalic acid (hydroxypivalinic acid), lactic acid and the like. Examples of the compound having a carboxy group of polyhydroxycarboxylic acid as an anionic group include dimethylolacetic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolpentanoic acid, dihydroxysuccinic acid, dimethylolpropionic acid and the like. In addition, compounds having both a sulfonic acid group and an active hydrogen group can also be mentioned. More specifically, for example, isethionic acid and the like can be mentioned. Among them, as the compound having both an anionic group and an active hydrogen group, hydroxypivalic acid or dimethylolpropionic acid is preferable.

[0071] The anionic hydrophilic group added to the blocked polyisocyanate is preferably neutralized with an amine compound which is a basic substance. Examples of the amine compound include, specifically, ammonia, water-soluble amino compounds and the like. Examples of the water-soluble amino compound include, specifically, monoethanolamine, ethylamine, dimethylamine, diethylamine, triethylamine, propylamine, dipropylamine, isopropylamine, diisopropylamine, triethanolamine, butylamine, dibutylamine, 2-ethylhexylamine, ethylenediamine, propylenediamine, methylethanolamine, dimethylethanolamine, diethylethanolamine, morpholine, and the like. Tertiary amines such as triethylamine and dimethylethanolamine are also included and can be used. These amine compounds may be used alone or in combination of two or more.

[0072] (Other components) In addition to the above block polyisocyanate, the BPI component may further contain additives such as a solvent. Examples of the solvent include 1-methylpyrrolidone, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether, 3-methoxy-3-methyl-1-butanol, ethylene glycol diethyl ether, diethylene glycol diethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether (DPDM), propylene glycol dimethyl ether, methyl ethyl ketone, acetone, methyl isobutyl ketone, propylene glycol monomethyl ether acetate, ethanol, methanol, iso-propanol, 1-propanol, iso-butanol, 1-butanol, tert-butanol, 2-ethylhexanol, cyclohexanol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, ethyl acetate, isopropyl acetate, butyl acetate, toluene, xylene, pentane, iso-pentane, hexane, iso-hexane, cyclohexane, solvent naphtha, mineral spirit, etc. These solvents may be used alone or in combination of two or more. From the viewpoint of dispersibility in water, as the solvent, those having a solubility in water of 5% by mass or more are preferable, and specifically, DPDM is preferable.

[0073] ≪Method for Producing BPI Component≫ The method for producing the BPI component is not particularly limited, but the following two methods can be mentioned. 1) A method of reacting the above polyisocyanate with the malonic ester having the above tertiary alkyl group and the malonic ester having the above secondary alkyl group or the malonic ester having the above primary alkyl group. 2) React the above polyisocyanate with at least one blocking agent selected from the group consisting of a malonic ester having the above tertiary alkyl group, a malonic ester having the above secondary alkyl group, and a malonic ester having the above primary alkyl group, and add an alcohol having a chain alkyl group to the obtained reaction product to introduce an alkyl group derived from the alcohol by transesterification of the terminal ester site of the reaction product.

[0074] Among the above two methods, considering the ease of the process and the ease of controlling the molar ratio of constitutional unit (II) / constitutional unit (I), the method of 2) is preferred.

[0075] The blocking reaction between the polyisocyanate and the blocking agent can be carried out regardless of the presence or absence of a solvent, and a blocked polyisocyanate can be obtained. Note that as the blocking agent, one kind each of a malonic ester having a primary alkyl group, a malonic ester having a secondary alkyl group, and a malonic ester having a tertiary alkyl group may be used, or two or more kinds may be used in combination. The addition amount of the blocking agent is usually preferably 80 mol% or more and 200 mol% or less, more preferably 90 mol% or more and 150 mol% or less, based on the total molar amount of the isocyanate groups.

[0076] When using a solvent, a solvent inert to the isocyanate group may be used. When using a solvent, the content of the non-volatile matter derived from the polyisocyanate and the blocking agent with respect to 100 parts by mass of the base paint composition is as described in the second embodiment.

[0077] In the blocking reaction, an organometallic salt such as tin, zinc, or lead, a tertiary amine-based compound, an alcoholate of an alkali metal such as sodium, etc. may be used as a catalyst. The addition amount of the catalyst varies depending on the temperature of the blocking reaction, etc., but is usually preferably 0.05 parts by mass or more and 1.5 parts by mass or less, more preferably 0.1 parts by mass or more and 1.0 parts by mass or less, based on 100 parts by mass of the polyisocyanate.

[0078] The blocking reaction can generally be carried out at a temperature of -20°C or higher and 150°C or lower, preferably at 0°C or higher and 100°C or lower, and more preferably at 10°C or higher and 80°C or lower. When the temperature of the blocking reaction is at or above the lower limit value, the reaction rate can be increased more, and when it is at or below the upper limit value, side reactions can be suppressed more.

[0079] After the blocking reaction, neutralization treatment may be carried out by adding an acidic compound or the like. As the acidic compound, an inorganic acid or an organic acid may be used. Examples of the inorganic acid include hydrochloric acid, phosphorous acid, phosphoric acid, etc. Examples of the organic acid include methanesulfonic acid, p-toluenesulfonic acid, dioctyl phthalate, dibutyl phthalate, etc.

[0080] When manufacturing by the method of 2), after the above-mentioned blocking reaction, a transesterification reaction is carried out. As the alcohol having a chain alkyl group used in the transesterification reaction of the method of 2), the same ones as those in the first embodiment can be used. In addition, the chain alkyl group of the alcohol may have the same chain alkyl group as the blocking agent, or may have a different chain alkyl group. When it has a chain alkyl group different from the blocking agent, it is preferable to use a monoalcohol having a chain alkyl group with a different number of alkyl substitutions from the blocking agent. Specifically, for example, when a malonic acid ester having a secondary alkyl group is used alone as the blocking agent, a monoalcohol having a tertiary alkyl group can be used.

[0081] When manufacturing by the method of 2), during or after the transesterification reaction, it is preferable to remove the generated alcohol or the residual amount of the added alcohol by distillation or the like under normal pressure or reduced pressure. Among them, in order to efficiently proceed with the transesterification reaction, it is preferable to remove the generated alcohol by performing operations such as distillation during the transesterification reaction. In this case, in order to efficiently remove the alcohol component generated by the exchange reaction, it is more preferable that the added alcohol component has a boiling point higher than that of the generated alcohol component.

[0082] The transesterification reaction can generally be carried out at 0°C or higher and 150°C or lower, preferably at 30°C or higher and 120°C or lower, and more preferably at 50°C or higher and 100°C or lower. When the temperature of the transesterification reaction is at or above the above lower limit value, the reaction rate can be increased more, and when it is at or below the above upper limit value, side reactions can be suppressed more.

[0083] The control of the molar ratio of the structural unit (II) to the structural unit (I) can be achieved by adjusting the molar ratio of the alcohol added to the blocked isocyanate group, or by adjusting the transesterification reaction temperature and transesterification reaction time, or by distilling off the generated alcohol, etc.

[0084] Also, when using a hydrophilic compound, the above polyisocyanate, the above active hydrogen compound, the above blocking agent, and the above hydrophilic compound may be reacted.

[0085] The reaction between the polyisocyanate and the active hydrogen compound, the reaction between the polyisocyanate and the hydrophilic compound, and the reaction between the polyisocyanate and the blocking agent can also be carried out simultaneously, or after any one of the reactions has been carried out in advance, the subsequent reactions can be carried out. Among them, it is preferable to first carry out the reaction between the polyisocyanate and the hydrophilic compound to obtain a hydrophilic compound-modified polyisocyanate modified by the hydrophilic compound, and then carry out the reaction between the obtained hydrophilic compound-modified polyisocyanate and the active hydrogen compound or the blocking agent simultaneously or in sequence. The reaction between the hydrophilic compound-modified polyisocyanate and the active hydrogen compound, and the reaction between the hydrophilic compound-modified polyisocyanate and the blocking agent can be carried out in either order first.

[0086] The reaction between the polyisocyanate and the hydrophilic compound may use an organometallic salt, a tertiary amine-based compound, or an alcoholate of an alkali metal as a catalyst. Examples of the metal constituting the organometallic salt include tin, zinc, lead, etc. Examples of the alkali metal include sodium, etc.

[0087] The reaction temperature between the polyisocyanate and the hydrophilic compound is preferably -20°C or higher and 150°C or lower, more preferably 30°C or higher and 130°C or lower. When the reaction temperature is at or above the lower limit value, the reactivity tends to be higher. Also, when the reaction temperature is at or below the upper limit value, side reactions tend to be more effectively suppressed. It is preferable to react completely with the polyisocyanate so that the hydrophilic compound does not remain in an unreacted state. By not remaining in an unreacted state, the water dispersion stability of the primer coating composition and the decrease in low-temperature curability when formed into a resin film tend to be more effectively suppressed.

[0088] For the reaction between the hydrophilic compound-modified polyisocyanate and the active hydrogen compound, and for the reaction between the hydrophilic compound-modified polyisocyanate and the blocking agent, the methods described as the above-mentioned active hydrogen compound modification reaction and the above-mentioned blocking reaction can be used.

[0089] ≪PI(A) component≫ The primer coating composition of this embodiment may contain a polyisocyanate component (A). The polyisocyanate component (A) contains one or more tertiary ammonium cations of an amine compound represented by the following general formula (1). Hereinafter, the polyisocyanate component (A) may be referred to as the "PI(A) component". The amine compound represented by the following general formula (1) may be referred to as the "amine compound (1)".

[0090]

Chemical formula

[0091] The PI(A) component contains a polyisocyanate containing a sulfonic acid anion group in the molecule and a tertiary ammonium cation of an amine compound, whereby the dispersibility stability of the base coating composition is improved. Further, the single-layer first coating film formed from the base coating composition and the coating film laminate including the first coating film have excellent hardness. That is, it is possible to achieve both the dispersibility stability and the excellent hardness of the base coating composition.

[0092] The PI(A) component usually contains, as an isocyanate component, an unmodified polyisocyanate, that is, a polyisocyanate not containing a sulfonic acid anion group in the molecule. Further, various properties of the base coating composition of the present embodiment described later are properties in a state containing a polyisocyanate containing a sulfonic acid anion group in the molecule and an unmodified polyisocyanate (a polyisocyanate not containing a sulfonic acid anion group in the molecule) unless otherwise specified.

[0093] Further, in the PI(A) component, the ratio of the unreacted polyisocyanate and the polyisocyanate containing a sulfonic acid anion group in the molecule can be calculated, for example, from the ratio of the isocyanate group containing a sulfonic acid anion group in the molecule to 100 mol of the isocyanate groups of the raw material polyisocyanate.

[0094] [Polyisocyanate containing a sulfonic acid anion group in the molecule] The polyisocyanate containing a sulfonic acid anion group in the molecule contained in the PI(A) component is a reaction product obtained by reacting a sulfonic acid having an active hydrogen group or an amine salt thereof with a polyisocyanate.

[0095] (Polyisocyanate) The polyisocyanate used for the polyisocyanate containing a sulfonic acid anion group in the molecule is not particularly limited, and examples thereof 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 being easily available industrially, the polyisocyanate used for the polyisocyanate containing a sulfonic acid anion group in the molecule is preferably at least one selected from the group consisting of aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates, and more preferably an aliphatic polyisocyanate.

[0096] The aliphatic diisocyanate is not particularly limited, and examples thereof include 1,4-diisocyanatobutane, 1,5-diisocyanatopentane (PDI), ethyl (2,6-diisocyanato) hexanoate, 1,6-diisocyanatohexane (hereinafter also referred to as "HDI"), 1,9-diisocyanatononane, 1,12-diisocyanatododecane, 2,2,4- or 2,4,4-trimethyl-1,6-diisocyanatohexane, and the like.

[0097] Although the alicyclic diisocyanate is not particularly limited, examples thereof include 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane (hereinafter also referred to as "hydrogenated XDI"), 1,3- or 1,4-diisocyanatocyclohexane, 3,5,5-trimethyl-1-isocyanato-3-(isocyanatomethyl)cyclohexane (hereinafter also referred to as "IPDI"), 4,4'-diisocyanato-dicyclohexylmethane (hereinafter also referred to as "hydrogenated MDI"), 2,5- or 2,6-diisocyanatomethylnorbornane, and the like.

[0098] Although the aromatic diisocyanate is not particularly limited, examples thereof include xylylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, and the like. Among them, as the diisocyanate, PDI, HDI, IPDI, hydrogenated XDI or hydrogenated MDI is preferable, and PDI and HDI are particularly preferable.

[0099] Although the polyisocyanate derived from the above diisocyanate is not particularly limited, examples thereof include the polyisocyanates shown in the following (a) to (i). (a) A polyisocyanate having a uretdione group obtained by cyclodimerizing two isocyanate groups. (b) A polyisocyanate having an isocyanurate group or an iminooxadiazinedione group obtained by cyclotrimerizing three isocyanate groups. (c) A polyisocyanate having a biuret group obtained by reacting three isocyanate groups with one water molecule. (d) A polyisocyanate having an oxadiazinetrione group obtained by reacting two isocyanate groups with one molecule of carbon dioxide. (e) A polyisocyanate having a plurality of urethane groups obtained by reacting one isocyanate group with one hydroxyl group. (f) A polyisocyanate having an allophanate group obtained by reacting two isocyanate groups with one hydroxyl group. (g) Polyisocyanates having an acylurea group obtained by reacting one isocyanate group with one carboxyl group; (h) Polyisocyanates having a urea group obtained by reacting one isocyanate group with one primary or secondary amine. (i) Polyisocyanates having an iminooxadiazinedione group.

[0100] The PI(A) component preferably contains the uretdione dimer of the above diisocyanate and the isocyanurate trimer of the above diisocyanate. That is, the PI(A) component preferably contains the above (a) and the above (b).

[0101] The PI(A) component has an isocyanurate group, and thus is excellent in hardness, water resistance, drying property, and weather resistance when formed into a coating film. In addition, in the PI(A) component, the uretdione group and the isocyanurate group may be contained in the same polyisocyanate molecule or in different polyisocyanate molecules, but are preferably contained in different polyisocyanate molecules.

[0102] In the present embodiment, the content of the uretdione dimer is preferably 1.0% by mass or more and 20.0% by mass or less based on the total mass of the PI(A) component, and the content of the uretdione dimer containing a sulfonic acid anion group in the molecule is preferably 0.15% by mass or less based on the total mass of the polyisocyanate containing a sulfonic acid anion group in the molecule, the uretdione dimer, and the isocyanurate trimer.

[0103] When the uretdione dimer is within the above range, a coating film laminate with good coating film hardness can be obtained. In addition, when the content of the uretdione dimer containing a sulfonic acid anion group in the molecule is within the above range, a coating film laminate having both excellent water resistance and stain resistance can be obtained.

[0104] The "uretdione dimer of the diisocyanate monomer" and the "isocyanurate trimer of the diisocyanate monomer" mentioned here are those that do not contain a sulfonic acid anion group in the molecule (unmodified uretdione dimer and isocyanurate trimer). Further, the "polyisocyanate containing a sulfonic acid anion group in the molecule" includes a uretdione dimer containing a sulfonic acid anion group in the molecule and an isocyanurate trimer containing a sulfonic acid anion group in the molecule.

[0105] The PI(A) component preferably contains an iminooxadiazinedione group in addition to a uretdione group and an isocyanurate group. Also, the specific molar ratio represented by the following formula (2) is preferably 0.05 or more and 0.60 or less. Specific molar ratio = (β + γ) / (α + β + γ) (2) (In formula (2), α represents the content ratio (mol%) of the isocyanurate group represented by the following formula (α), β represents the content ratio (mol%) of the iminooxadiazinedione group represented by the following formula (β), and γ represents the content ratio (mol%) of the uretdione group represented by the following formula (γ).)

[0106]

Chemical formula

[0107] The lower limit value of the specific molar ratio represented by formula (2) is preferably 0.08, more preferably 0.12, still more preferably 0.15, even more preferably 0.18, and even more preferably 0.20. The upper limit value of the specific molar ratio is preferably 0.50, more preferably 0.45, still more preferably 0.40, even more preferably 0.37, and even more preferably 0.35.

[0108] When the specific molar ratio is equal to or higher than the above lower limit value, excellent compatibility with the hydroxyl group-containing resin component can be exhibited. Further, when the specific molar ratio is equal to or lower than the above upper limit value, even when cured at a low temperature, the performance such as the hardness of the coating film laminate is less likely to deteriorate.

[0109] As a method for obtaining the PI(A) component in which the specific molar ratio represented by the formula (2) is 0.05 or more and 0.60 or less, for example, by the iminooxadiazinedione formation reaction, uretdione formation reaction, and allophanate formation reaction described later, an iminooxadiazinedione group, a uretdione group, and an allophanate group are formed to adjust the specific molar ratio.

[0110] The molar ratio of the iminooxadiazinedione group is preferably 0.05 or more and 0.60 or less as the molar ratio of β / (α + β + γ) (α to γ have the same meaning as α to γ represented by the above formula (2)). The lower limit value 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 value 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.

[0111] When the above molar ratio is 0.05 or more, there is a tendency to exhibit more excellent compatibility with the hydroxyl group-containing resin component, and when the above molar ratio is 0.60 or less, there is a tendency to suppress the deterioration of the coating film performance in low-temperature curing.

[0112] From the viewpoint of obtaining a coating film laminate having high hardness, the above molar ratio is more preferably 0.50 or less. As a method for obtaining the PI(A) component in which the above molar ratio is 0.05 or more and 0.60 or less, for example, by the iminooxadiazinedione formation reaction described later, an iminooxadiazinedione group is formed to adjust the above molar ratio.

[0113] The PI(A) component may contain a reaction product with an alcohol from the viewpoints of improving acid resistance, alkali resistance, and salt water spray resistance, and suppressing low viscosity and dilution turbidity. That is, the PI(A) component preferably contains either one or both of the above (e) and the above (f).

[0114] The alcohol preferably has a hydroxyl group with an average number of 2.0 or more and 3.5 or less per molecule and a number average molecular weight of 450 or less.

[0115] From the viewpoints of suppressing low viscosity and dilution turbidity and achieving both improvement in acid resistance, alkali resistance, and salt water 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, more preferably 2.0 or more and 2.5 or less. Further, the number average molecular weight is preferably 400 or less, more preferably 350 or less, in terms of suppressing low viscosity and in terms of dispersibility and film hardness.

[0116] Examples of alcohols that satisfy the average number of hydroxyl groups and the 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, neopentyl glycol, 2-methyl-2,3-butanediol, 1,6-hexanediol, 1,2-hexanediol, 2,5-hexanediol, 2-methyl-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, 2,2-diethyl-1,3-propanediol, etc. Examples of triols include glycerin, trimethylolpropane, etc. Examples of tetraols include pentaerythritol, etc.

[0117] Examples of polymerized alcohols include polyester polyols, polyether polyols, acrylic polyols, polyolefin polyols, polycarbonate diols, etc.

[0118] Examples of the polyester polyol include a polyester polyol obtained by a condensation reaction of a dibasic acid selected from the group consisting of carboxylic acids such as succinic acid, adipic acid, sebacic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid, and terephthalic acid, alone or as a mixture, and a polyhydric alcohol selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, glycerin, etc., alone or as a mixture, and polycaprolactones obtained by ring-opening polymerization of ε-caprolactone using a polyhydric alcohol, etc.

[0119] Examples of the polyether polyol include polyether polyols obtained by randomly or block-adding a single or a mixture of alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, and styrene oxide to a single or a mixture of polyhydroxy compounds using a strongly basic catalyst such as hydroxides, alcoholates, and alkylamines of lithium, sodium, potassium, etc., or a composite metal cyanide complex such as metal porphyrin and zinc hexacyanocobaltate complex, further polyether polyols obtained by reacting an alkylene oxide with a polyamine compound such as ethylenediamines, and so-called polymer polyols obtained by polymerizing acrylamide, etc. using these polyethers as a medium.

[0120] The polycarbonate diol has a structural unit in which two alcohol groups and one carbonate group are dehydrated and condensed, repeating. Also, the polycarbonate diol includes those obtained by copolymerizing a first diol having 2 to 20 carbon atoms, a second diol having 2 to 20 carbon atoms (hereinafter also simply referred to as "two kinds of diols"), and a carbonate compound. These alcohols may be used alone or in combination of a plurality.

[0121] The mass fraction of the alcohol with respect to the total mass of the polyisocyanate component in the present embodiment is preferably 0.01% by mass or more and 4.5% by mass or less. Further, from the viewpoint of achieving both dilution turbidity and the chromaticity, acid resistance, and salt water spray resistance of the polyisocyanate component, it is more preferably 0.1% by mass or more and 2.5% by mass or less.

[0122] In addition, the polyisocyanate used in the polyisocyanate containing a sulfonic acid anion group in the molecule may contain an aliphatic triisocyanate. Examples of the aliphatic triisocyanate include 1,3,6 - triisocyanatohexane, 1,8 - diisocyanato - 4 - isocyanatomethyloctane, 2 - isocyanatoethyl - 2,6 - diisocyanato - hexanoate, and the like.

[0123] In addition, these polyisocyanates may be modified with a nonionic hydrophilic group such as alkoxypolyalkylene glycol or a vinyl polymer having a hydroxyl group and a nonionic hydrophilic group. In addition, these polyisocyanates can be used alone or in combination of two or more.

[0124] When the PI(A) component contains a polyisocyanate modified with a nonionic hydrophilic group, the content of the polyisocyanate modified with a nonionic hydrophilic group is preferably 1% by mass or more and 60% by mass or less. The upper limit value of the content of the polyisocyanate modified with a nonionic hydrophilic group is preferably 60% by mass, more preferably 40% by mass, further preferably 30% by mass, and particularly preferably 20% by mass. Also, the lower limit value is preferably 2% by mass, more preferably 5% by mass, and further preferably 10% by mass. When the content of the polyisocyanate modified with a nonionic hydrophilic group is within the above range, the pot life of the primer coating composition dispersed in water or a main agent containing water is good, and a coating film laminate excellent in water resistance can be easily obtained.

[0125] (Nonionic hydrophilic group) The nonionic hydrophilic group is not particularly limited, and examples thereof include polyalkylene glycol alkyl ethers. From the viewpoint of lowering the viscosity of the base coating composition, the number of hydroxyl groups possessed by the polyalkylene glycol alkyl ether is preferably one. Preferred polyalkylene glycol alkyl ethers have a structure represented by the following general formula (N1).

[0126] [Chemical formula]

[0127] In the general formula (N1), R 41 is an alkylene group having 1 to 4 carbon atoms, R 42 is an alkyl group having 1 to 4 carbon atoms, and n11 is 4.0 or more and 20 or less.

[0128] The polyalkylene glycol alkyl ether is not a single component, but an aggregate of substances having different numbers of degrees of polymerization n (hereinafter, may be referred to as "degree of polymerization n" or simply "n"). Therefore, the degree of polymerization n is represented by its average value. In formula (N1), the degree of polymerization n is described as n11. When polyisocyanate is blended into the aqueous main agent, thickening often becomes a problem when mixed with the main agent. When there is a lot of thickening, the polyisocyanate cannot be uniformly dispersed in the main agent, and there is a tendency to lead to a decrease in the physical properties of the coating film. Therefore, from the viewpoints 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. When n11 is equal to or greater than the above lower limit value, the emulsifying power increases and the dispersibility tends to improve. On the other hand, when it is equal to or less than the above upper limit value, the viscosity increase can be prevented, and it tends to be easily dispersed.

[0129] Polyalkylene glycol alkyl ethers can also be used in combinations of two or more with different values of n. The value of n of the polyalkylene glycol alkyl ether can be measured by the proton nuclear magnetic resonance (NMR) method.

[0130] In the general formula (N1), R 41 is an alkylene group having 1 to 4 carbon atoms from the viewpoint of imparting hydrophilicity, and an ethylene group having 2 carbon atoms is preferable from the viewpoint of being able to impart more hydrophilicity. Also, R 42 is an alkyl group having 1 to 4 carbon atoms from the viewpoint of imparting hydrophilicity, and a methyl group having 1 carbon atom is preferable from the viewpoint of being able to impart more hydrophilicity.

[0131] Examples of the polyalkylene glycol alkyl ether include, but are not limited to, the following: polyethylene glycol (mono) methyl ether, poly(ethylene, propylene) glycol (mono) methyl ether, and polyethylene glycol (mono) ethyl ether. Among them, polyethylene glycol (mono) methyl ether is preferable from the viewpoint of imparting hydrophilicity.

[0132] (Method for producing polyisocyanate) (I) Method for producing polyisocyanate containing isocyanurate group The method for producing a polyisocyanate containing an isocyanurate group is not particularly limited, and examples thereof include a method in which a diisocyanate monomer is reacted using an isocyanuration catalyst and an alcohol as a co-catalyst.

[0133] Examples of the isocyanuration catalyst used in the production of isocyanurate-type polyisocyanate include sodium salts of fatty acids, potassium salts, quaternary ammonium salts, and the like. Examples of the fatty acid include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid and the like. These fatty acids may be linear or branched.

[0134] Examples of the quaternary ammonium include tetramethylammonium, tetrabutylammonium, butyltrimethylammonium, benzyltrimethylammonium, dibenzyldimethylammonium, phenyltrimethylammonium and the like.

[0135] The amount of the isocyanuration catalyst used varies depending on the amounts of the cocatalyst and the solvent used, but usually, when HDI is used as a raw material of the polyisocyanate, it can be 0.001% by mass or more and 0.05% by mass or less based on the mass of HDI.

[0136] As the alcohol as the cocatalyst, for example, a phenolic hydroxy compound or an alcoholic hydroxy compound can be used. Thereby, the isocyanuration reaction proceeds more easily. Examples of the phenolic hydroxy compound include phenol, cresol, trimethylphenol and the like.

[0137] Examples of the alcoholic hydroxy compound include linear alcohols, branched-chain alcohols, cyclic alcohols, polyhydric alcohols and the like. Examples of the linear alcohol include methanol, ethanol, propanol, n-butanol, 1-hexanol and the like.

[0138] Examples of the branched-chain alcohol include isobutanol, 2-ethylhexanol and the like. Examples of the cyclic alcohol include cyclohexanol and the like. Examples of the polyhydric alcohol include ethylene glycol and the like.

[0139] The amount of alcohol used correlates with the abundance of allophanate groups in the polyisocyanate in the polyisocyanate component. When using HDI as the raw material of the polyisocyanate, it is preferably 500 ppm or more and 30,000 ppm or less by mass ratio with respect to HDI. By setting the amount of alcohol used to be equal to or less than the above upper limit value, the abundance ratio of isocyanurate groups in the polyisocyanate contained in the final polyisocyanate component is appropriately maintained, and the weather resistance and chemical resistance become better. On the other hand, by setting the amount of alcohol used to be equal to or more than the above lower limit value, the reaction rate is maintained higher, and better productivity is achieved in terms of economy.

[0140] In the production of isocyanurate-type polyisocyanate, as the addition timing of alcohol, it is sufficient that alcohol is added so as to be present in the reaction system during the isocyanuration reaction. Specifically, it may be added at any timing before the isocyanuration reaction, simultaneously with the isocyanuration catalyst, and during the progress of the nuration reaction after the completion of the addition of the isocyanuration catalyst. Also, among the above timings, it may be added at only one of the timings, or it may be added at all timings. The addition method of alcohol may be either batch addition or continuous addition. However, from the viewpoint of controlling the reaction and heat generation, continuous addition is preferred for the addition of alcohol during the progress of the isocyanuration reaction. Regarding the addition of alcohol before the isocyanuration reaction, batch addition is preferred in terms of economy.

[0141] The isocyanuration reaction temperature is preferably 70 °C or lower, more preferably 30 °C or higher and 65 °C or lower. By setting the isocyanuration reaction temperature to be equal to or lower than the above upper limit value, a polyisocyanate with better color tone can be obtained. On the other hand, by setting the isocyanuration reaction temperature to be equal to or higher than the above lower limit value, the reaction rate is maintained more appropriately, and better productivity is achieved in terms of economy.

[0142] The reaction time varies depending on the amount of catalyst, the amount and addition method of alcohol as a co-catalyst, and the reaction temperature, etc., but usually it can be set to 1 hour or more and 6 hours or less.

[0143] Since the decrease in the content of isocyanate groups (NCO%) accompanying the progress of isocyanuration can be measured by titration analysis, the reaction may be stopped when a predetermined NCO% is reached. The NCO%, viscosity, etc. of the isocyanurate-type polyisocyanate can be freely changed depending on the NCO% at the time of reaction termination.

[0144] As the reaction terminator, an acidic compound can be used. Examples of the acidic compound 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, and the like. Further, similar compounds of these acidic compounds may be used.

[0145] The amount of the reaction terminator used can be 0.5 to 10 times the molar amount, preferably 1 to 8 times the molar amount, relative to 1 mole of the carboxylic acid content in the isocyanuration catalyst. When a reaction terminator soluble in the mixed solution of the diisocyanate monomer as the raw material and the polyisocyanate produced by the reaction is used, it can be around 1 times the molar amount relative to 1 mole of the carboxylic acid content in the isocyanuration catalyst. When an insoluble reaction terminator is used, it can be 2 to 8 times the molar amount relative to 1 mole of the carboxylic acid content in the isocyanuration catalyst.

[0146] After the addition of the reaction terminator, heat curing may be carried out to complete the termination reaction. When heat curing is carried out, the 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. When the temperature is below the above upper limit, the decrease in the 1-nylon body in the polyisocyanate component containing the isocyanurate-type polyisocyanate obtained can be more suppressed, and further, the decrease in chromaticity and the increase in viscosity due to the progress of the formation of more isocyanurate-type polyisocyanate can be more suppressed. When the temperature is above the above lower limit, the growth of the salt generated by the termination reaction can be accelerated, and particularly in the case of a combination of a catalyst forming an insoluble salt and a reaction terminator, a salt of a size that can be filtered can be more easily formed, resulting in better productivity in terms of economy.

[0147] The heat curing time varies depending on the temperature, but can be 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. Depending on the temperature, when the time is below the above upper limit, coloring and the increase in viscosity due to further polymerization of the polyisocyanate can be more suppressed. On the other hand, when the time is above the above lower limit, the formation and growth of the salt can be made more sufficient, and in the case of an insoluble salt, separation by filtration can be made easier.

[0148] (II) Method for producing a polyisocyanate containing a uretdione group The method for producing a polyisocyanate containing a uretdione group is not particularly limited, and examples thereof include a method in which a diisocyanate is subjected to a uretdionization reaction using a uretdionization catalyst or the like.

[0149] Examples of the uretdionization reaction catalyst include, but are not limited to, tertiary phosphines such as trialkylphosphine, tris(dialkylamino)phosphine, and cycloalkylphosphine.

[0150] Examples of the trialkylphosphine include tri-n-butylphosphine, tri-n-octylphosphine, and the like.

[0151] Examples of the tris(dialkylamino)phosphine include tris(dimethylamino)phosphine and other tris(dialkylamino)phosphines.

[0152] Examples of the cycloalkylphosphine include cyclohexyl-di-n-hexylphosphine and the like.

[0153] Many of these compounds simultaneously promote the isocyanuration reaction and produce isocyanurate-type polyisocyanates in addition to the uretdione group-containing polyisocyanates.

[0154] When the desired yield is achieved, a deactivator for the uretdionization reaction catalyst such as phosphoric acid or methyl p-toluenesulfonate is added to stop the uretdionization reaction.

[0155] In addition, a uretdione group-containing polyisocyanate can also be obtained by heating the diisocyanate monomer without using the above uretdionization reaction catalyst.

[0156] When not using the above uretdionization reaction catalyst, the heating temperature can be 120°C or higher, preferably 150°C or higher and 170°C or lower. Also, the heating time can be 1 hour or longer and 4 hours or shorter.

[0157] (III) Iminooxadiazinedione group-forming iminooxadiazinization reaction As the catalyst for the iminooxadiazinedione group-forming iminooxadiazinization reaction, for example, the catalysts described in the following (Catalyst 1) and (Catalyst 2), which are generally known as iminooxadiazinedione catalysts, can be used.

[0158] (Catalyst 1) (Poly)hydrogen fluoride represented by the general formula M[Fn] or the general formula M[Fn(HF)m], such as tetramethylammonium fluoride hydrate and tetraethylammonium fluoride (wherein m and n are each integers satisfying the relationship m / n > 0, and M represents an n-charged cation (mixture) or one or more radicals having a total valence of n).

[0159] (Catalyst 2) A compound composed of a general formula R1-CR’2-C(O)O- such as 3,3,3-trifluorocarboxylic acid; 4,4,4,3,3-pentafluorobutanoic acid; 5,5,5,4,4,3,3-heptafluoropentanoic acid; 3,3-difluoroprop-2-enoic acid, or the general formula R2=CR’-C(O)O- (wherein R1 and R2 each represent a perfluoroalkyl group having 1 to 30 carbon atoms which may be branched, cyclic, and / or unsaturated as required, and R’ is the same or different and is selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, and an aryl group, and may contain a heteroatom as required), and a quaternary ammonium cation or a quaternary phosphonium cation.

[0160] From the viewpoint of easy availability, the above (Catalyst 1) is preferred, and from the viewpoint of safety, the above (Catalyst 2) is preferred.

[0161] The usage amount of these catalysts is preferably 10 mass ppm or more and 1000 mass ppm or less based on the mass of the charged diisocyanate. The lower limit value is more preferably 20 mass ppm, still more preferably 40 mass ppm, and even more preferably 80 mass ppm. The upper limit value is more preferably 800 mass ppm, still more preferably 600 mass ppm, and even more preferably 500 mass ppm or less.

[0162] Moreover, the reaction temperature is preferably 40 to 120°C. The lower limit value of the reaction temperature is more preferably 50°C, and even more preferably 55°C. Also, the upper limit value of the reaction temperature is more preferably 100°C, even more preferably 90°C, and even more preferably 80°C. When the reaction temperature is 40°C or higher, the reaction rate tends to be maintained at a high level, and when the reaction temperature is 120°C or lower, the coloring of the polyisocyanate can be suppressed.

[0163] (IV) Method for producing polyisocyanate having allophanate group The polyisocyanate having an allophanate group (allophanate group-containing polyisocyanate) can be obtained by using an alcohol compound or the like in combination with a diisocyanate and using an allophanatization reaction catalyst.

[0164] The alcohol compound used for producing the allophanate group-containing polyisocyanate is preferably an alcohol formed only of carbon, hydrogen, and oxygen, although it is not limited thereto. Also, the alcohol compound preferably has a molecular weight of 200 or less.

[0165] Examples of the alcohol compound include monoalcohol, dialcohol, etc. Examples of the monoalcohol include methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, etc. Examples of the dialcohol include ethylene glycol, 1,3-butanediol, neopentyl glycol, 2-ethylhexanediol, etc. These alcohol compounds may be used alone or in combination of two or more. Among them, the alcohol compound is preferably monoalcohol.

[0166] The amount of the alcohol compound used is not limited to the following, but is preferably 10 / 1 or more and 1000 / 1 or less, more preferably 100 / 1 or more and 1000 / 1 or less, in terms of the molar ratio of the isocyanate group of HDI to the hydroxyl group of the alcohol compound. By being not less than the above lower limit value, in the polyisocyanate obtained, it is possible to secure a more appropriate number of average isocyanate groups.

[0167] Examples of the allophanatization reaction catalyst include, but are not limited to, alkyl carboxylates such as tin, lead, zinc, bismuth, zirconium, and zirconyl.

[0168] Examples of the alkyl carboxylate of tin (organotin compound) include tin 2-ethylhexanoate and dibutyltin dilaurate. Examples of the alkyl carboxylate of lead (organolead compound) include lead 2-ethylhexanoate. Examples of the alkyl carboxylate of zinc (organic zinc compound) include zinc 2-ethylhexanoate.

[0169] Examples of the alkyl carboxylate of bismuth include bismuth 2-ethylhexanoate. Examples of the alkyl carboxylate of zirconium include zirconium 2-ethylhexanoate. Examples of the alkyl carboxylate of zirconyl include zirconyl 2-ethylhexanoate.

[0170] When the desired yield is achieved, a deactivator for the allophanatization reaction catalyst such as phosphoric acid or methyl p-toluenesulfonate can be added to stop the allophanatization reaction.

[0171] The amount of the above allophanatization reaction catalyst used is preferably 10 ppm or more and 10000 ppm or less, more preferably 10 ppm or more and 1000 ppm or less, still more preferably 10 ppm or more and 500 ppm or less, based on the mass ratio to the diisocyanate as the raw material.

[0172] The lower limit of the reaction temperature for allophanatization is preferably 60°C, more preferably 70°C, still more preferably 80°C, and particularly preferably 90°C. On the other hand, the upper limit of the reaction temperature for allophanatization is preferably 160°C, more preferably 155°C, still more preferably 150°C, and particularly preferably 145°C.

[0173] That is, the reaction temperature for allophanatization is preferably 60°C or higher and 160°C or lower, more preferably 70°C or higher and 155°C or lower, still more preferably 80°C or higher and 150°C or lower, and particularly preferably 90°C or higher and 145°C or lower.

[0174] By the allophanatization reaction temperature being at or below the above upper limit value, characteristic changes such as coloring of the resulting polyisocyanate can be more effectively prevented.

[0175] The lower limit of the reaction time is preferably 0.2 hours, more preferably 0.4 hours, still more 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, still more preferably 4 hours, particularly preferably 3 hours, and most preferably 2 hours.

[0176] That is, the reaction time for allophanatization is preferably 0.2 hours or more and 8 hours or less, more preferably 0.4 hours or more and 6 hours or less, still 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.

[0177] By setting the reaction time for allophanatization to be at or above the above lower limit value, a lower viscosity can be achieved, and by setting it to be at or below the above upper limit value, coloring of the polyisocyanate itself can be more suppressed.

[0178] Moreover, the above isocyanuration reaction catalyst can be used as an allophanatization reaction catalyst. When performing an allophanatization reaction using the above isocyanuration reaction catalyst, an isocyanurate-type polyisocyanate is also generated simultaneously. Among them, from the viewpoint of improving productivity in terms of economy, it is preferable to use the above isocyanuration reaction catalyst as an allophanatization reaction catalyst and perform an allophanatization reaction and an isocyanuration reaction.

[0179] The above isocyanuration reaction and the above uretdione formation reaction can be carried out sequentially or in parallel.

[0180] Moreover, when an allophanatization reaction is involved, since the manufacturing process can be simplified, it is preferable to carry out the isocyanuration reaction and the allophanatization reaction in parallel first, and then carry out the uretdione formation reaction. The allophanatization reaction can be stopped when the desired allophanate group content is reached. The allophanatization reaction is not limited to the following. For example, it can be stopped by adding an acidic compound such as phosphoric acid, acidic phosphate ester, sulfuric acid, hydrochloric acid, or sulfonic acid compound to the reaction solution. Thereby, the allophanatization reaction catalyst can be inactivated by neutralization, thermal decomposition, or chemical decomposition, etc. After the reaction is stopped, filtration is performed if necessary.

[0181] (V) Thin-film distillation process and heat treatment process Since the reaction solution immediately after the reaction stop usually contains diisocyanate monomers such as unreacted HDI, it is preferable to remove this by a thin-film evaporator, extraction, etc.

[0182] The thin-film distillation process is a process for enhancing the separation efficiency of low-boiling components from high-boiling components. As specific countermeasures, for example, measures such as reducing the flow rate and extending the residence time, increasing the temperature during distillation, increasing the wiper rotation speed, and increasing the number of distillations can be considered, and any method can be selected. Among them, for the purpose of reducing the thermal history and enhancing the separation efficiency, the method of increasing the number of distillations is preferable. The number of distillations is preferably 1 or more and 5 or less.

[0183] In addition, the content of the diisocyanate monomer remaining in the polyisocyanate component is preferably 0.50% by mass or less, more preferably 0.40% by mass or less, still more preferably 0.30% by mass or less, particularly preferably 0.20% by mass or less, and most preferably 0.10% by mass or less.

[0184] By setting the content of the diisocyanate monomer remaining in the polyisocyanate component to be equal to or less than the above upper limit value, the toxicity of the polyisocyanate component can be further reduced, and the safety can be further improved. Further, when it is 0.10% by mass or less, a coating film laminate having particularly excellent finished appearance can be obtained.

[0185] (Sulfonic acid having an active hydrogen group) In the sulfonic acid having an active hydrogen group used for the polyisocyanate containing a sulfonate anion group in the molecule, examples of the active hydrogen group include an amino group, a carboxy group, a hydroxyl group, etc. Among them, the active hydrogen group is preferably at least one selected from the group consisting of an amino group and a hydroxyl group, and more preferably at least one selected from the group consisting of a hydroxyl group.

[0186] (Sulfonic acid (S1)) When the active hydrogen group is a hydroxyl group, examples of the sulfonic acid having a hydroxyl group include a compound represented by the following general formula (S14) (hereinafter abbreviated as "sulfonic acid (S1)"), etc.

[0187] [Chemical formula]

[0188] In the general formula (S1), R 51 is a hydrocarbon group having 1 to 10 carbon atoms which may contain at least one selected from the group consisting of a hydroxyl group, an ether bond, an ester bond, a carbonyl group, and an imino group. R 51 may contain a ring structure. The ring structure is an aromatic ring, a 5-membered or 6-membered ring containing two nitrogen atoms, or a 5-membered or 6-membered ring containing a nitrogen atom and an oxygen atom.

[0189] ·R 51 In the general formula (S1), R 51 is a hydrocarbon group having 1 to 10 carbon atoms which may contain at least one selected from the group consisting of a hydroxyl group, an ester bond (-COO-), an ether bond (-O-), a carbonyl group (-C(=O)-), an imino group (-NR-), and a ring structure.

[0190] The hydrocarbon group having 1 to 10 carbon atoms may be a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 10 carbon atoms. The divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms is preferably a linear alkylene group having 1 to 6 carbon atoms. When it is a linear alkylene group having 1 to 6 carbon atoms, a part of the linear alkylene group may be a group containing a ring structure. The alkylene group having 1 to 6 carbon atoms may be linear or branched.

[0191] Among them, R 51 is preferably a linear alkylene group having 1 to 6 carbon atoms, a divalent aromatic hydrocarbon group (arylene group) having 6 to 10 carbon atoms, a divalent alkylene group having 1 to 6 carbon atoms containing an aromatic ring, a divalent alkylene group having 1 to 6 carbon atoms containing a 5-membered or 6-membered ring containing two nitrogen atoms, or a divalent alkylene group having 1 to 6 carbon atoms containing a 5-membered or 6-membered ring containing a nitrogen atom and an oxygen atom.

[0192] Preferred sulfonic acids (S1) include, for example, 2-hydroxyethanesulfonic acid, 3-hydroxypropanesulfonic acid, 4-hydroxybutanesulfonic 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, and the like.

[0193] These compounds are only a part of the preferred sulfonic acids (S1), and the preferred sulfonic acids (S1) are not limited to these. Also, one of these sulfonic acids (S1) may be used, or two or more thereof may be used in combination.

[0194] Among them, as the sulfonic acid having a hydroxyl group, it is preferably at least one selected from the group consisting of 2-hydroxyethanesulfonic acid, 3-hydroxypropanesulfonic acid, hydroxybenzenesulfonic acid, and hydroxy(methyl)benzenesulfonic acid. In addition, in the case where the primer coating composition of the present embodiment contains two or more amine salts of sulfonic acid, the sulfonic acids (S1) may be the same as or different from each other. Further, the sulfonic acid used for the polyisocyanate containing a sulfonic acid anion group in the molecule may form a salt with an amine compound described later.

[0195] (Sulfonic acid (S2)) When the active hydrogen group is an amino group, examples of the sulfonic acid having an amino group include compounds represented by the following general formula (S2) (hereinafter abbreviated as "sulfonic acid (S2)") and the like.

[0196]

Chemical formula

[0197] In the general formula (S2), R 61 and R 63 are, independently of each other, a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms which may contain a hydroxyl group. At least one of R 61 and R 63 is a hydrogen atom. R 62 is a hydrocarbon group having 1 to 12 carbon atoms which may contain a hydroxyl group.

[0198] ·R 61 and R 63 In the general formula (S2), R 61 and R 63 are, independently of each other, a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms which may contain a hydroxyl group. R 61 and R 63 may be the same as or different from each other. At least one of R 61 and R 63 is a hydrogen atom. That is, when R 61 is a hydrocarbon group having 1 to 12 carbon atoms which may contain a hydroxyl group, R 63 is a hydrogen atom. Also, when R 63 is a hydrocarbon group having 1 to 12 carbon atoms which may contain a hydroxyl group, R 61 is a hydrogen atom. Also, both R 61 and R 63 may be hydrogen atoms.

[0199] The hydrocarbon group having 1 to 12 carbon atoms may be a monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms. The monovalent aliphatic hydrocarbon group having 1 to 12 carbon atoms is preferably a linear alkyl group having 1 to 6 carbon atoms or a cyclic alkyl group having 3 to 6 carbon atoms. The linear alkyl group having 1 to 6 carbon atoms may be linear or branched.

[0200] Among them, R 61 and R 63It is preferably a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, or a cyclic alkyl group having 3 to 6 carbon atoms, respectively.

[0201] ·R 62 R 62 is a hydrocarbon group having 1 to 12 carbon atoms which may contain a hydroxyl group. The hydrocarbon group having 1 to 12 carbon atoms may be a divalent aliphatic hydrocarbon group having 1 to 12 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms. The divalent aliphatic hydrocarbon group having 1 to 12 carbon atoms is preferably a linear alkylene group having 1 to 12 carbon atoms. The linear alkyl group having 1 to 12 carbon atoms may be linear or branched. Among them, R 62 is preferably a divalent linear alkylene group having 1 to 6 carbon atoms or a divalent aromatic hydrocarbon group (arylene group) having 6 to 10 carbon atoms.

[0202] Preferred sulfonic acids (S2) 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-cyclohexylaminobutanesulfonic acid, 2-cyclohexylmethylaminoethanesulfonic acid, 3-cyclohexylmethylaminopropanesulfonic acid, 3-cyclohexylmethylaminoisobutylsulfonic acid, 4-cyclohexylmethylaminobutanesulfonic acid, 2-methylcyclohexylaminoethanesulfonic acid, 3-methylcyclohexylaminopropanesulfonic acid, 3-methylcyclohexylaminoisobutylsulfonic acid, 4-methylcyclohexylaminobutanesulfonic acid, 2-dimethylcyclohexylaminoethanesulfonic acid, 3-dimethylcyclohexylaminopropanesulfonic acid, 3-dimethylcyclohexylaminoisobutylsulfonic acid, 4-dimethylcyclohexylaminobutanesulfonic acid, 2-trimethylcyclohexylaminoethanesulfonic acid, 3-trimethylcyclohexylaminopropanesulfonic acid, 3-trimethylcyclohexylaminoisobutylsulfonic acid, 4-trimethylcyclohexylaminobutanesulfonic 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, and the like. These compounds are only a part of the preferred sulfonic acids (S2), and the preferred sulfonic acids (S2) are not limited thereto. Also, one of these sulfonic acids (S2) may be used, or two or more thereof may be used in combination.

[0203] Among these, as the sulfonic acid having an amino group, at least one selected from the group consisting of 2-cyclohexylaminoethanesulfonic acid, 3-cyclohexylaminopropanesulfonic acid, 4-cyclohexylaminobutanesulfonic acid, 3-cyclohexylmethylaminopropanesulfonic acid, 3-(p-methylcyclohexylamino)propanesulfonic acid, 3-(3,3,5-trimethylcyclohexylamino)propanesulfonic acid, 4-(p-methylcyclohexylamino)butanesulfonic 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 is preferable. In addition, when the primer coating composition of this embodiment contains two or more amine salts of sulfonic acid, the sulfonic acids (5) may be the same as or different from each other.

[0204] [Amine compound] The PI(A) component contains one or more tertiary ammonium cations of an amine compound represented by the following general formula (1). Here, the "tertiary ammonium cation of an amine compound" means a protonated product formed by the coordination of a proton (H + ) to the "N" in the amine compound represented by the following general formula (1). In addition, in the polyisocyanate component (A), the amine compound may form a salt with the above sulfonic acid.

[0205]

Chemical formula

[0206] In the general formula (1), R 31 , R 32 and R 33 are each independently a hydrocarbon group having 1 to 10 carbon atoms which may contain an ether bond. R31 , R 32 and R 33 At least one selected from the group consisting of may contain a ring structure, and R 31 , R 32 and R 33 Two or more selected from the group consisting of may be bonded to each other to form a ring structure. The ring structure is an aromatic ring, a cycloalkyl group having 5 or 6 carbon atoms, a 5-membered or 6-membered ring in which R 31 and R 32 are bonded to each other, or a polycyclic polycyclic ring in which R 31 and R 32 and R 33 are bonded to each other.

[0207] ·R 31 , R 32 and R 33 R 31 , R 32 and R 33 are, independently of each other, hydrocarbon groups having 1 to 10 carbon atoms which may contain an ether bond.

[0208] The hydrocarbon group having 1 to 10 carbon atoms may be a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms or the like. As the monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, a linear alkyl group having 1 to 10 carbon atoms or a cyclic alkyl group having 3 to 10 carbon atoms is preferable. When it is a linear alkyl group having 1 to 10 carbon atoms, a part of the alkyl group may be a group containing an aromatic hydrocarbon. The linear alkyl group having 1 to 10 carbon atoms may be linear or branched.

[0209] 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-methyldioctylamine, N,N-dimethylallylamine, N-methyldiallylamine, tripropylamine, tributylamine, N,N-diethylpropylamine, 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, 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, quinuclidine and the like. These compounds are only a part of the preferred amine compounds, and the preferred amine compounds are not limited thereto. Further, these amine compounds may be used alone or in combination of two or more.

[0210] Among them, 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 is preferred.

[0211] Moreover, N,N-dimethylpropylamine, N,N-dimethylbutylamine, N,N-diethylmethylamine, N,N-diisopropylethylamine, tripropylamine, tributylamine, N,N-dipropyloctylamine, N,N-dimethylcyclohexylamine or N-methylpiperidine is more preferred, and N,N-dimethylpropylamine, N,N-dimethylbutylamine, N,N-diethylmethylamine, N,N-diisopropylethylamine, tripropylamine, tributylamine, N,N-dipropyloctylamine is most preferred.

[0212] [Other amine compounds] The PI(A) component may contain the tertiary ammonium cation of other amine compounds in addition to the tertiary ammonium cation of the above amine compounds.

[0213] The other amine compounds may be any compounds other than the above amine compounds and are not particularly limited. Specifically, examples of the other amine compounds include those shown in the following (a) to (b). Also, these other amine compounds may be used alone or in combination of two or more.

[0214] Examples of the tertiary amines having a chain aliphatic hydrocarbon group 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, 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, triamylamine, trihexylamine and the like.

[0215] Examples of the tertiary amines having an aromatic hydrocarbon group include N,N-dimethylphenylamine, N,N-diethylphenylamine, N,N-diphenylmethylamine and the like.

[0216] [Method for producing amine salt of sulfonic acid] When the sulfonic acid forms a salt with the amine compound, that is, when it is 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 and subjecting them to a neutralization reaction.

[0217] The neutralization reaction may be carried out in advance before reacting with the polyisocyanate. Or, it may be carried out simultaneously when reacting with the polyisocyanate. Or, it may be carried out by adding an amine compound after reacting the polyisocyanate with a sulfonic acid having a hydroxyl group.

[0218] It is preferable to carry out the neutralization reaction in advance before reacting with the polyisocyanate. In the neutralization reaction, the mixing ratio of the sulfonic acid having a hydroxyl group and the amine compound is preferably such that the molar ratio of the sulfonic acid having a hydroxyl group / amine compound is 0.5 or more and 2 or less, and more preferably 0.8 or more and 1.5 or less.

[0219] When carrying out the neutralization reaction in advance, the temperature and time can be appropriately determined according to the progress of the reaction. However, the temperature is usually preferably about 0°C or more and 100°C or less, and the mixing time is preferably about 10 minutes or more and 24 hours or less.

[0220] The solvent used in the preparation of the amine salt of the sulfonic acid having a hydroxyl group is preferably water or a hydrophilic solvent. The hydrophilic solvent is not particularly limited, and examples thereof include alcohols, ether alcohols, ketones, amide solvents, and the like. These solvents can be used alone or in combination.

[0221] Examples of the alcohols include methanol, ethanol, propanol, butanol, isopropanol, and the like.

[0222] Examples of the 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, dipropylene glycol monomethyl ether, and the like.

[0223] Examples of the ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, and the like.

[0224] Examples of the amide solvents include N,N-dimethylformamide, N,N-dimethylacetamide, and the like.

[0225] After the neutralization reaction, it is preferable to remove water or a hydrophilic solvent.

[0226] [Properties of the PI(A) component] From the viewpoints of emulsifying properties and coating film physical properties, it is preferable that the isocyanate groups of the polyisocyanate as a raw material are modified at a ratio of 0.25 mol or more and 50 mol or less, more preferably 0.5 mol or more and 20 mol or less, and even more preferably 1 mol or more and 10 mol or less, based on 100 mol of the isocyanate groups of the polyisocyanate.

[0227] In addition, from the viewpoint of solvent resistance of the coating film, when the non-volatile content is 100% by mass, the isocyanate group content of the PI(A) component is preferably 10% by mass or more and 25% by mass or less, and more preferably 15% by mass or more and 24% by mass or less. The method for controlling the isocyanate group content within the above range is not particularly limited, and examples thereof include a method of adjusting the blending ratio of sulfonic acid and polyisocyanate.

[0228] In addition, from the viewpoint of solvent resistance of the coating film, the number average molecular weight of the polyisocyanate (including polyisocyanate containing a sulfonic acid anion group in the molecule and unreacted polyisocyanate) used for the PI(A) component 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. The method for controlling the number average molecular weight within the above range is not particularly limited, and examples thereof include a method of adjusting the blending ratio of sulfonic acid, amine compound, and polyisocyanate.

[0229] The number average molecular weight can be measured, for example, using gel permeation chromatography (GPC).

[0230] Also, the average functionality of the polyisocyanate (including modified polyisocyanate and unreacted polyisocyanate) used in the PI(A) component 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, from the viewpoints of the solvent resistance of the coating film and the isocyanate group retention rate. The method for controlling the average functionality within the above range is not particularly limited, and examples include a method of adjusting the blending ratio of a sulfonic acid, an amine compound, and a polyisocyanate.

[0231] The isocyanate group content, non-volatile content, and average functionality can be measured by the methods described in the examples below.

[0232] (Other components) The PI(A) component is a composition containing a polyisocyanate containing a sulfonic acid anion group in the molecule, an unreacted polyisocyanate, and a tertiary ammonium cation of the amine compound (1). The primer coating composition of the present embodiment may contain other components in addition to the polyisocyanate containing a sulfonic acid anion group in the molecule, the unreacted polyisocyanate, and the tertiary ammonium cation of the amine compound (1).

[0233] The other components are not particularly limited, and examples include solvents, antioxidants, light stabilizers, polymerization inhibitors, surfactants, and the like.

[0234] The solvent used in the polyisocyanate component (a) may be a hydrophilic solvent or a hydrophobic solvent. These solvents can be used alone or in combination.

[0235] The hydrophobic solvent is not particularly limited, and examples thereof include mineral spirit, solvent naphtha, LAWS (Low Aromatic White Spirit), HAWS (High Aromatic White Spirit), toluene, xylene, cyclohexane, esters, ketones, and amides.

[0236] Examples of the esters include ethyl acetate, butyl acetate, and the like.

[0237] Examples of the ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and the like.

[0238] Examples of the amides include N,N-dimethylformamide, N,N-dimethylacetamide, and the like.

[0239] The hydrophilic solvent is not particularly limited, and examples thereof include alcohols, ethers, and esters of ether alcohols.

[0240] Examples of the alcohols include methanol, ethanol, propanol, isopropanol, 2-ethylhexanol, and the like.

[0241] Examples of the ethers include diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, dipropylene glycol dimethyl ether, and the like.

[0242] Examples of esters of 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, dipropylene glycol monomethyl ether acetate, and the like.

[0243] In the PI(A) component, the content ratio of the solvent is preferably 0% by mass or more and 90% by mass or less, 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, based on the total mass of the base paint composition.

[0244] Also, from the perspective of global environmental protection, the content ratio of the solvent in the PI(A) component is preferably 0% by mass.

[0245] Examples of the antioxidant and the light stabilizer include those shown in the following (a) to (e). These may be contained alone or in combination of two or more.

[0246] (a) Aliphatic, aromatic or alkyl group-substituted aromatic esters of phosphoric acid or phosphorous acid, or hypophosphite derivatives. (b) Phosphorus compounds such as phenylphosphonic acid, phenylphosphinic acid, diphenylphosphonic acid, polyphosphonate, dialkyl pentaerythritol diphosphite, and dialkyl bisphenol A diphosphite. (c) Phenolic derivatives (particularly, hindered phenol compounds). (d) Sulfur-containing compounds such as thioether compounds, dithiocarboxylate compounds, mercaptobenzimidazole compounds, thiocarbanylides, and thiodipropionate esters. (e) Tin compounds such as tin maleate and dibutyltin monoxide.

[0247] Examples of the polymerization inhibitor include hydroquinones, phenols, cresols, catechols, benzoquinones, etc. Specific examples of the polymerization inhibitor include benzoquinone, p-benzoquinone, p-toluquinone, p-xylenequinone, naphthoquinone, 2,6-dichloroquinone, hydroquinone, trimethylhydroquinone, catechol, p-t-butylcatechol, 2,5-di-t-butylhydroquinone, monomethylhydroquinone, p-methoxyphenol, 2,6-di-t-butyl-p-cresol, hydroquinone monomethyl ether, etc. These may be contained alone or in combination of two or more.

[0248] Examples of the surfactant include known anionic surfactants, cationic surfactants, amphoteric surfactants, etc.

[0249] In the PI(A) component, the total content of the antioxidant, the light stabilizer, the polymerization inhibitor, and the surfactant is preferably 0% by mass or more and 10% by mass or less, 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, based on the total mass of the base coating composition.

[0250] ≪Production method of PI(A) component≫ The production method of the PI(A) component preferably includes, for example, the steps shown in the following (1) or (2).

[0251] (1) A step of mixing and reacting an amine salt of a sulfonic acid having an active hydrogen group with a polyisocyanate. (2) A step of mixing and reacting a sulfonic acid having an active hydrogen group, a polyisocyanate, and the above amine compound.

[0252] In step (1), it is preferable to preliminarily prepare the amine salt of the sulfonic acid and then add it to the polyisocyanate.

[0253] In step (2), a sulfonic acid having an active hydrogen group and an amine compound may be added to the polyisocyanate simultaneously or in sequence.

[0254] Among them, step (1) is preferred, and it is more preferred to add the amine salt of sulfonic acid to the polyisocyanate after adjusting it in advance.

[0255] In the reaction step, the mixing ratio of the sulfonic acid having an active hydrogen group or its amine salt and 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, in terms of the molar ratio of isocyanate group / hydroxyl group from the viewpoints of emulsifying properties and coating film physical properties.

[0256] In the reaction step, the reaction temperature and reaction time can be appropriately determined according to the progress of the reaction, but the reaction temperature is preferably 0°C or higher and 150°C or lower, and the reaction time is preferably 30 minutes or longer and 48 hours or shorter.

[0257] In addition, in the reaction step, a known ordinary catalyst may be used as appropriate. The catalyst is not particularly limited, and examples include those shown in the following (a) to (f). These may be used alone or in combination.

[0258] (a) Organotin compounds such as tin octoate, tin 2-ethylhexanoate, tin ethylcaproate, tin laurate, tin palmitate, dibutyltin oxide, dibutyltin dichloride, dibutyltin diacetate, dibutyltin dimaleate, dibutyltin dilaurate, dioctyltin diacetate, dioctyltin dilaurate. (b) Organozinc compounds such as zinc chloride, zinc octoate, zinc 2-ethylhexanoate, zinc 2-ethylcaproate, zinc stearate, zinc naphthenate, zinc acetylacetonate. (c) Organic titanium compounds. (d) Organic zirconium compounds. (e) Tertiary amines such as triethylamine, tributylamine, N,N - diisopropylethylamine, N,N - dimethylethanolamine, etc. (f) Diamines such as triethylenediamine, tetramethylethylenediamine, 1,4 - diazabicyclo[2.2.2]octane, etc.

[0259] In the method for producing the PI(A) component, a solvent may or may not be used. The solvent used in the method for producing the PI(A) component may be a hydrophilic solvent or a hydrophobic solvent. Examples of the hydrophilic solvent and the hydrophobic solvent are the same as those exemplified in the above other components.

[0260] Also, in the method for producing the PI(A) component, in addition to the sulfonic acid having a hydroxyl group, the polyisocyanate, and the amine compound, at least one selected from the group consisting of an antioxidant, a light stabilizer, a polymerization inhibitor, and a surfactant may be added. Examples of the antioxidant, the light stabilizer, the polymerization inhibitor, and the surfactant are the same as those exemplified in the above other components.

[0261] Examples of the production method when the above polyisocyanate component contains a reaction product with an alcohol include, for example, the following (4) to (6). (4) A method of performing the reaction of the polyisocyanate, the alcohol, and the amine salt of the sulfonic acid having an active hydrogen group (or the sulfonic acid having an active hydrogen group and the above amine compound) all at once. (5) A method of reacting the polyisocyanate, the alcohol, and the amine salt of the sulfonic acid having an active hydrogen group (or the sulfonic acid having an active hydrogen group and the above amine compound), and then mixing another polyisocyanate. (6) A method of separately producing the reaction product (E) of the polyisocyanate and the alcohol and the reaction product (F) of the polyisocyanate and the amine salt of the sulfonic acid having an active hydrogen group (or the sulfonic acid having an active hydrogen group and the above amine compound), and mixing (E) and (F) at a desired mass ratio.

[0262] Among the above methods (4) to (6), from the viewpoint of shortening the manufacturing process and manufacturing time and obtaining an undercoat paint composition with stable physical properties, the method of (4) or (5) is preferred. Further, from the viewpoint of suppressing dilution turbidity and alkali resistance, the method of (5) is more preferred.

[0263] Furthermore, it is preferable to carry out the reaction of an amine salt of a sulfonic acid having an active hydrogen group, a polyisocyanate, and an alcohol, because it is less likely to cause dilution turbidity and low-temperature turbidity.

[0264] The reaction of a polyisocyanate with an alcohol and a sulfonic acid having an active hydrogen group or an amine salt thereof containing an active hydrogen group may be carried out using an organometallic salt, a tertiary amine-based compound, or an alcoholate of an alkali metal as a catalyst. Examples of the metal constituting the organometallic salt include tin, zinc, lead, etc. Examples of the alkali metal include sodium, etc.

[0265] The reaction temperature of the polyisocyanate with the alcohol and the sulfonic acid having an active hydrogen group or an amine salt thereof containing an active hydrogen group is preferably -20°C or higher and 150°C or lower, more preferably 30°C or higher and 130°C or lower. When the reaction temperature is at or above the above lower limit value, the reactivity tends to be higher. Also, when the reaction temperature is at or below the above upper limit value, side reactions tend to be more effectively suppressed.

[0266] It is preferable to react completely with the polyisocyanate so that the alcohol and the sulfonic acid having an active hydrogen group or an amine salt thereof containing an active hydrogen group do not remain in an unreacted state. By not remaining in an unreacted state, the water dispersibility of the PI(A) component and the pot life of the undercoat paint composition tend to be better.

[0267] When it is a sulfonic acid having a hydroxyl group, the production method of the PI(A) component preferably includes the above-described step (1) or (2).

[0268] Among them, it is preferably step (1), and it is more preferable to add the amine salt of sulfonic acid to the polyisocyanate after adjusting it in advance.

[0269] ≪Hydroxyl group-containing resin component≫ The hydroxyl group-containing resin component in the primer coating composition of the present embodiment is not particularly limited. For example, 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. can be mentioned. Among them, as the resins, acrylic resins, polyurethane resins or polyester resins are preferable.

[0270] The acrylic resin is obtained by copolymerizing a monomer mixture composed of a hydrophilic group-containing polymerizable unsaturated monomer such as a hydroxyl group-containing polymerizable unsaturated monomer and a carboxyl group-containing polymerizable unsaturated monomer and other polymerizable unsaturated monomers, and has a weight average molecular weight of 5,000 to 100,000, preferably 10,000 to 90,000, more preferably 20,000 to 80,000 water-soluble acrylic resins, acrylic resin emulsions having a weight average molecular weight of 50,000 or more, preferably 75,000 or more, more preferably 100,000 or more, etc. can be mentioned.

[0271] Examples of the hydroxyl group-containing polymerizable unsaturated monomer include hydroxyalkyl esters of acrylic acid or methacrylic acid such as 2-hydroxyethyl (meth)acrylate, 2- or 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate; polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, etc. These can be used alone or in combination of two or more.

[0272] Examples of the carboxyl group-containing polymerizable unsaturated monomers include (meth)acrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, and half monoalkyl esterified products of dicarboxylic acids among them. Examples of the polymerizable unsaturated monomers containing hydrophilic groups other than these include polymerizable unsaturated monomers containing polyalkylene chains such as polyethylene glycol (meth)acrylate and polypropylene glycol (meth)acrylate.

[0273] Examples of the other polymerizable unsaturated monomers include alkyl esters or cycloalkyl esters having 1 to 24 carbon atoms of (meth)acrylic acid such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, lauryl (meth)acrylate, and isobornyl (meth)acrylate; hydroxyalkyl esters of (meth)acrylic acid such as 2-hydroxyethyl (meth)acrylate, 2- or 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; glycidyl (meth)acrylate, acrylonitrile, acrylamide, styrene, vinyltoluene, vinyl acetate, vinyl chloride, 1,6-hexanediol diacrylate, etc. These can be used alone or in combination of two or more. The copolymerization of the monomer mixture can be carried out by a method known per se. For example, when a water-soluble acrylic resin is desired, it can be carried out by a solution polymerization method or the like, and when an acrylic resin emulsion is desired, it can be carried out by an emulsion polymerization method or the like.

[0274] When the acrylic resin is an acrylic resin emulsion obtained by emulsion polymerization, it may be a multilayer-structured particulate emulsion obtained by emulsion polymerizing the monomer mixture in multiple steps in the presence of water and an emulsifier.

[0275] The carboxyl groups of the acrylic resin can be neutralized with the aforementioned basic substance as necessary. The acrylic resin contained preferably has an acid value generally in the range of 10 to 100 mgKOH / g, more preferably 15 to 80 mgKOH / g, particularly preferably 20 to 60 mgKOH / g, and a hydroxyl value generally in the range of 10 to 250 mgKOH / g, more preferably 20 to 200 mgKOH / g, particularly preferably 30 to 150 mgKOH / g.

[0276] The polyester resin generally includes those obtained by neutralizing a polyester resin prepared by subjecting a polyhydric alcohol, a polybasic acid, and, if necessary, a monobasic acid, an oil component (including this fatty acid, etc.) to an esterification reaction. The weight average molecular weight of this polyester resin is generally suitably in the range of about 3000 to 100000, preferably 4000 to 70000, more preferably 5000 to 30000.

[0277] Examples of the above polyhydric alcohol include ethylene glycol, diethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, 2,2-dimethylpropanediol, glycerin, trimethylolpropane, pentaerythritol, ethylene oxide adducts or propylene oxide adducts of bisphenol compounds, etc. These can be used alone or in combination of two or more.

[0278] Examples of the polybasic acid include phthalic acid, isophthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, maleic acid, succinic acid, adipic acid, sebacic acid, trimellitic acid, pyromellitic acid and their anhydrides, etc. These can be used alone or in combination of two or more. Examples of the monobasic acid include benzoic acid, t-butylbenzoic acid, etc. Examples of the oil component include castor oil, dehydrated castor oil, safflower oil, soybean oil, linseed oil, tall oil, coconut oil and their fatty acids, etc. These can be used alone or in combination of two or more.

[0279] In the above polyester resin, the carboxyl group can be introduced, for example, by using a polybasic acid such as trimellitic acid or pyromellitic acid having three or more carboxyl groups in one molecule as a part of the polybasic acid component, or by adding a half ester to a dicarboxylic acid. Further, the introduction of a hydroxyl group can be easily carried out, for example, by using a polyhydric alcohol such as glycerin or trimethylolpropane having three or more hydroxyl groups in one molecule as a part of the polyhydric alcohol component.

[0280] The carboxyl group of the above polyester resin can be neutralized using a basic substance. As the basic substance, a water-soluble one is preferred. For example, ammonia, methylamine, ethylamine, propylamine, butylamine, dimethylamine, trimethylamine, triethylamine, ethylenediamine, morpholine, methylethanolamine, dimethylethanolamine, diethanolamine, triethanolamine, diisopropanolamine, 2-amino-2-methylpropanol, etc. can be mentioned, and these can be used alone or in combination of two or more.

[0281] The polyester resin preferably has an acid value generally in the range of 10 to 100 mgKOH / g, more preferably 20 to 80 mgKOH / g, particularly preferably 20 to 50 mgKOH / g, and a hydroxyl value generally in the range of 10 to 300 mgKOH / g, more preferably 30 to 200 mgKOH / g, particularly preferably 50 to 200 mgKOH / g. As the polyurethane resin, a hydrophilic polyurethane resin that can be dissolved or dispersed in water can be preferably used. For example, (i) an aliphatic and / or alicyclic diisocyanate, (ii) a diol having a number average molecular weight of 500 to 5000, (iii) a low molecular weight polyhydroxyl compound, and (iv) dimethylolalkanoic acid are usually reacted at an NCO / OH equivalent ratio in the range of 1 / 0.5 to 1 / 0.95, particularly 1 / 0.6 to 1 / 0.9, by a one-shot method or a multi-step method to obtain a urethane prepolymer, which can be obtained by chain extension and emulsification after neutralization or while neutralizing. In particular, a water dispersion of a self-emulsifying urethane resin having an average particle diameter of 0.001 to 1.0 μm, particularly about 0.02 to 0.3 μm, obtained by distilling off part or all of the organic solvent used in the production process is preferred.

[0282] The polyurethane resin preferably has an acid value generally in the range of 10 to 60 mgKOH / g, more preferably 20 to 50 mgKOH / g, particularly 20 to 40 mgKOH / g, and a hydroxyl value generally in the range of 10 to 60 mgKOH / g, more preferably 20 to 50 mgKOH / g, particularly 20 to 40 mgKOH / g.

[0283] Examples of the polyether resins include those obtained by using any of the following methods (1) to (3). (1) Polyether polyols or polytetramethylene glycols obtained by adding a single or a mixture of alkylene oxides to a single or a mixture of polyhydric alcohols. (2) Polyether polyols obtained by reacting a polyfunctional compound with an alkylene oxide. (3) So-called polymer polyols obtained by polymerizing acrylamide or the like using the polyether polyols obtained in (1) or (2) as a medium.

[0284] Examples of the polyhydric alcohol include glycerin and propylene glycol. Examples of the alkylene oxide include ethylene oxide and propylene oxide. Examples of the polyfunctional compound include ethylenediamine, ethanolamines, and the like.

[0285] Examples of the epoxy resins include novolak type epoxy resins, β-methyl epichlorohydrin type epoxy resins, cyclic oxirane type epoxy resins, glycidyl ether type epoxy resins, glycol ether type epoxy resins, epoxy type aliphatic unsaturated compounds, epoxidized fatty acid esters, ester type polyvalent carboxylic acids, aminoglycidyl type epoxy resins, halogenated type epoxy resins, resorcin type epoxy resins, and other epoxy resins, and resins obtained by modifying these epoxy resins with amino compounds, polyamide compounds, and the like. Examples of the fluorine-containing resins include copolymers of fluoroolefins, cyclohexyl vinyl ether, hydroxyalkyl vinyl ether, monocarboxylic acid vinyl esters, and the like disclosed in Reference 1 (Japanese Patent Laid-Open No. 57-34107) and Reference 2 (Japanese Patent Laid-Open No. 61-275311).

[0286] ≪Deionized water≫ The primer coating composition of the present embodiment may be an aqueous coating composition containing deionized water. The content ratio of deionized water is preferably 20% by mass or more and 90% by mass or less, more preferably 30% by mass or more and 80% by mass or less, based on the total amount of the aqueous coating composition.

[0287] ≪Basic composition≫ When the polyol contained in the primer coating composition of the present embodiment is a carboxyl group-containing polyol, the carboxyl group is preferably neutralized with a basic composition. The basic composition is not particularly limited, but there is no particular limitation as long as the acid dissociation constant (pKa) is 7.0 or more. If the pKa is 7.0 or more, it can be used as a neutralizing agent for carboxyl groups such as polyols. The acid dissociation constant (pKa) was measured at 20°C by the potentiometric titration method.

[0288] In the present invention, the addition amount of the basic composition is preferably 30 mol% or more when the amount of the basic group is 100 mol% of the amount of the carboxyl group of the polyol. The lower limit is preferably 50 mol%, more preferably 70 mol%, still more preferably 100 mol% or more. The upper limit is preferably 500 mol%, more preferably 400 mol%, still more preferably 300 mol%. In the present invention, it is considered that the basic composition is present in an amount in excess of the amount forming the neutralized salt of the carboxyl group of the polyol. The carboxyl group of the polyol in this case is based on the acid component charged during the production of the polyol.

[0289] The basic composition preferably comprises a weakly basic compound having an acid dissociation constant (pKa) of 7.0 to 8.5 and a basic compound having a pKa exceeding 8.5, and the composition ratio of the weakly basic compound to the total basic composition is 20 mol% or more.

[0290] The lower limit of the composition ratio of the weakly basic compound in the total basic composition is preferably 30 mol%, more preferably 40 mol%, still more preferably 50 mol%. In the present invention, since the pH of the adjusted paint composition does not become too high when 20 mol% or more of the weakly basic compound is added to the total basic composition, it is suitable.

[0291] The upper limit of the pKa of the weakly basic compound is preferably 8.3 or less, more preferably 8.0 or less. Specific examples of the weakly basic compound having a pKa of 7.0 to 8.5 include morpholine derivatives such as morpholine (pKa: 8.4), N-allylmorpholine (pKa: 7.1), N-methylmorpholine (pKa: 7.4), N-ethylmorpholine (pKa: 7.7), tertiary amines such as triallylamine (pKa: 8.3), triethanolamine (pKa: 7.8), 2-methylimidazole (pKa: 7.8), phthalimide (pKa: 8.3), and the like. Among them, N-allylmorpholine, N-methylmorpholine, N-ethylmorpholine, triethanolamine, and 2-methylimidazole are more preferable, and further preferably, N-methylmorpholine and N-ethylmorpholine.

[0292] Specific examples of basic compounds having a pKa exceeding 8.5 include trimethylamine (pKa: 9.8), triethylamine (pKa: 11.0), dimethylethanolamine (pKa: 9.4), and the like.

[0293] The pH during the formulation of the primer coating composition of the present invention is preferably 7.0 to 9.0. As the lower limit, more preferably, it is 7.5, still more preferably, it is 7.8. As the upper limit, more preferably, it is 8.6, still more preferably, it is 8.4, and most preferably, it is 8.2. If the pH of the coating composition is 7.0 to 9.0, the stability of pigments such as aluminum and additives such as rheology control agents incorporated therein can be maintained.

[0294] The basic composition may be added in advance to the polyol or the blocked polyisocyanate component, or may be added after mixing and dispersing the polyol and the blocked polyisocyanate composition. Further, the basic composition may be added as a solution previously dissolved in water, a solvent, or the like.

[0295] ≪Nonionic dispersant≫ The primer coating composition of this embodiment preferably contains at least two or more nonionic dispersants. Here, "two or more" means a plurality of nonionic dispersants having different HLB values. By containing a plurality of nonionic dispersants having different HLB values, the emulsifiability of the blocked polyisocyanate in water can be improved, and the water dispersion stability can be improved. This effect is achieved when at least two or more nonionic dispersants are mixed, the difference between the nonionic dispersant having the maximum HLB value and the nonionic dispersant having the minimum HLB value is 5 or more, and the weighted average HLB value of all the nonionic dispersants contained in the primer coating composition is 14 or more and 17 or less, and the effect is strongly exhibited.

[0296] The difference between the nonionic dispersant having the maximum HLB value and the minimum HLB value is preferably 7 or more, more preferably 8 or more, and still more preferably 9 or more. Also, as the upper limit, 20 or less is preferable, and 15 or less is more preferable.

[0297] The HLB (Hydrophile-Lipophile Balance) value of the nonionic dispersant is generally used as a value representing the degree of affinity of the dispersant for oil and water, and can be calculated by the following formula. HLB value = 20 × sum of formula weights of hydrophilic parts / molecular weight

[0298] The nonionic dispersant to be used is not particularly limited as long as the HLB value calculated by the above method is within a specific range. Specific examples of the nonionic dispersant include, for example, polyoxyethylene alkyl ether type compounds, polyoxyalkylene derivative type compounds, polyoxyethylene polycyclic phenyl ether type compounds, sorbitan fatty acid ester type compounds, glycerin fatty acid ester type compounds, polyoxyethylene fatty acid ester type compounds, polyoxyethylene castor oil type compounds, polyoxyethylene alkylamine type compounds, and the like. Among these nonionic dispersants, polyoxyethylene alkyl ether type compounds and polyoxyethylene polycyclic phenyl ether type compounds are particularly preferable.

[0299] The content of the nonionic dispersant is preferably 1% by mass or more and 30% by mass or less, more preferably 1.5% by mass or more and 20% by mass or less, still more preferably 2% by mass or more and 15% by mass or less, and even more preferably 3% by mass or more and 10% by mass or less, based on the total amount of the block polyisocyanate. When the content of the nonionic dispersant is at least the above lower limit value, the storage stability of the aqueous coating composition can be made better. On the other hand, when it is at most the above upper limit value, the hardness of the coating film laminate can be made better.

[0300] When the system contains a nonionic dispersant satisfying the above conditions, an anionic dispersant may be further used. Specific examples of the anionic dispersant include, for example, fatty acid salt type compounds, alkyl sulfate ester compounds, polyoxyethylene alkyl ether sulfate ester salt type compounds, polyoxyethylene alkyl ether sulfate type compounds, polyoxyethylene polycyclic phenyl ether sulfate type compounds, polyoxyalkylene alkenyl ether sulfate type compounds, alkylbenzene sulfonate type compounds, sulfosuccinate type compounds, alkyl phosphate type compounds, and the like. Examples of the polyoxyethylene alkyl ether sulfate type compounds include ammonium polyoxyethylene alkyl ether sulfate and sodium polyoxyethylene alkyl ether sulfate. Examples of the polyoxyethylene polycyclic phenyl ether sulfate type compounds include ammonium polyoxyethylene polycyclic phenyl ether sulfate and sodium polyoxyethylene polycyclic phenyl ether sulfate. Examples of the polyoxyalkylene alkenyl ether sulfate type compounds include ammonium polyoxyalkylene alkenyl ether sulfate. These anionic dispersants may be used alone or in combination of two or more.

[0301] Among these anionic dispersants, ammonium polyoxyethylene polycyclic phenyl ether sulfate, sodium polyoxyethylene polycyclic phenyl ether sulfate, ammonium polyoxyethylene alkyl ether sulfate, and sodium polyoxyethylene alkyl ether sulfate are particularly preferred.

[0302] <<Other Additives>> The primer coating composition of this embodiment may further contain other additives. Examples of other additives include, for example, curing agents that can react with crosslinkable functional groups in polyols, curing catalysts, solvents, pigments (extender pigments, coloring pigments, metallic pigments, etc.), ultraviolet absorbers, light stabilizers, radical stabilizers, anti-yellowing agents that suppress coloring during the baking process, coating surface modifiers, flow modifiers, pigment dispersants, defoaming agents, thickeners, film-forming aids, and the like.

[0303] In addition, as pigments (extender pigments, coloring pigments, metallic pigments, etc.), ultraviolet absorbers, light stabilizers, radical stabilizers, anti-yellowing agents that suppress coloring during the baking process, coating surface modifiers, flow modifiers, pigment dispersants, defoaming agents, thickeners, and film-forming aids, known ones can be appropriately selected and used.

[0304] [Method for Producing Primer Coating Composition] The primer coating composition of the present invention can be obtained by mixing the above PI(A) component and the above hydroxyl group-containing resin component, and, if necessary, various additive components, etc., using a known method. For example, various additives are added to the hydroxyl group-containing resin component or its aqueous dispersion or aqueous solution as necessary. Next, the above PI(A) component or its aqueous dispersion is added as a curing agent, and, if necessary, water or a solvent is further added to adjust the viscosity. Then, the primer coating composition can be obtained by forcibly stirring with a stirring device.

[0305] (NCO / OH Ratio) From the viewpoint of low-temperature curability, it is preferable that the isocyanate groups in the polyisocyanate component be contained in a ratio of 1.1 to 2.0 equivalents, 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, per 1 equivalent of the hydroxyl groups in the hydroxyl group-containing resin component.

[0306] (Other Components) The primer coating composition of the present invention may appropriately contain pigments such as coloring pigments and extender pigments, curing agents other than polyisocyanate components such as melamine resins (e.g., fully alkylated type, methylol type alkyl, imino group type alkyl, etc.), curing catalysts, thickeners, ultraviolet absorbers, light stabilizers, defoamers, plasticizers, organic solvents, surface modifiers, anti-settling agents, and other paint additives as necessary.

[0307] The primer coating composition of the present invention can be applied onto an object to be coated by a method known per se, such as air spray coating, airless spray coating, rotary atomization coating, curtain coating, etc., and electrostatic application may be performed during coating. Among these, methods such as air spray coating and rotary atomization coating are preferred. The coating amount is preferably an amount such that the cured film thickness is usually 10 to 50 μm, preferably 10 to 40 μm.

[0308] The primer layer formed by the primer coating composition of the present invention may be a single-layer primer layer having a first coating film layer formed directly on the object to be coated, or may be a multi-layer primer layer having a second coating film layer on the first coating film layer.

[0309] Here, the primer coating composition for forming the first coating film layer is referred to as the first primer coating composition, and the primer coating composition for forming the second coating film layer is referred to as the second primer coating composition.

[0310] The first primer coating composition preferably contains the above BPI component and a hydroxyl group-containing resin component. The second primer coating composition preferably contains either one or both of the above BPI component and the above PI(A) component and a hydroxyl group-containing resin component.

[0311] By containing the BPI component, the second primer coating composition makes it difficult for curing agents and the like to migrate from the first primer coating composition to the second primer coating composition, and it becomes difficult for the orientation of the pigments contained in the second primer coating composition to be disturbed. Therefore, it is presumed that the finished appearance of the coating film laminate becomes good.

[0312] The content of the BPI component in the second undercoat paint composition is preferably 0.5% by mass or more and 20% by mass or less, 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, based on the total mass of the second undercoat paint composition. By being within the above range, the water resistance and the finished appearance when forming a coating film laminate are improved.

[0313] (NCO / OH) The molar equivalent ratio (NCO / OH) of the isocyanate group of the blocked polyisocyanate to the hydroxyl group of the polyol contained in the first undercoat paint composition is determined by the physical properties of the required coating film laminate, but is preferably 0.01 or more and 2.0 or less, more preferably 0.02 or more and 1.0 or less, and even more preferably 0.04 or more and 0.8 or less. By being within the above range, a coating film laminate excellent in the storage stability and curability of the undercoat paint composition can be obtained. When the second undercoat paint composition contains the BPI component, in the second undercoat paint composition, NCO / OH is preferably 1.0 or less, and more preferably less than 1.0. By NCO / OH being below the above upper limit value, the polyisocyanate component of the coating paint composition can more easily penetrate well into the first undercoat paint composition and the second undercoat paint composition (the first uncured coating film and the second uncured coating film), and the first undercoat paint composition and the second undercoat paint composition can be cured more efficiently. When NCO / OH in the undercoat paint composition is 1.0, NCO / OH of the coating paint composition is more than 1.0.

[0314] <Coating paint composition> One aspect of the present invention is a coating paint composition for forming a coating film laminate on an object to be coated. The coating paint composition is a paint composition for forming the outermost layer of the coating film laminate. In one aspect of the present invention, the coating paint composition is a topcoat paint composition used in the final lamination step for forming a coating film laminate.

[0315] The coating paint composition contains a polyisocyanate component (T). Hereinafter, the polyisocyanate component (T) may be referred to as the "PI(T) component". The PI(T) component contains a triisocyanate compound represented by the following general formula (II).

[0316] [Chemical formula] (In general formula (II), a plurality of Y 1 are each independently a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms which may contain either or both of an ester structure and an ether bond. A plurality of Y 1 may be the same or different from each other. R 1 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms.) (1) Y 1 In general formula (II), a plurality of Y 1 are each independently a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms which may contain one or more selected from the group consisting of an ester structure and an ether structure. A plurality of Y 1 may be the same or different from each other.

[0317] Y 1 The divalent hydrocarbon group having 1 to 20 carbon atoms that does not contain an ester structure and an ether structure in Y may be an aliphatic group or an aromatic group. The aliphatic group may be linear, branched or cyclic. Examples of the linear or branched aliphatic group include an alkanediyl group (alkylene group), an alkylidene group, etc. Examples of the cyclic aliphatic group include a cycloalkylene group, etc. Examples of the aromatic group include an arylene group such as a phenylene group. Among them, as the divalent hydrocarbon group having 1 to 20 carbon atoms, an alkylene group is preferable. Examples of the alkylene group include a methylene group, a dimethylene group, a trimethylene group, a tetramethylene group, an octamethylene group, and the like. Among these, the tetramethylene group is preferable as the alkylene group.

[0318] Y 1 Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms and containing at least one selected from the group consisting of an ester structure (-COO-) and an ether structure (-O-) in Y include a group represented by the following general formula (II-1) (hereinafter sometimes referred to as "group (II)"). *1 -(CH2) n1 -X-(CH2) n2 - *2 (II-1)

[0319] In the general formula (II-1), *1 represents a bond to C in the general formula (II), and *2 represents a bond to N in the general formula (II). Also, n1 and n2 are integers such that 1 ≦ n1 + n2 ≦ 20. That is, neither n1 nor n2 can be 0, and n2 is preferably 1 or more. Among them, n1 and n2 are preferably each independently an integer of 0 or more and 20 or less, more preferably an integer of 0 or more and 4 or less, and even more preferably an integer of 0 or more and 2 or less. Examples of the combination of n1 and n2 include the combination of n1 = 0 and n2 = 2, and the combination of n1 = 2 and n2 = 2. Also, in group (II), X is preferably an ester structure.

[0320] When at least one of the plurality of Ys 1 has one or more selected from the group consisting of an aliphatic group and an aromatic group, the isocyanate component can have a lower viscosity. Also, when at least one of the plurality of Ys 1 has one or more selected from the group consisting of an aliphatic group and an alicyclic group, the weather resistance of the coating film can be made better. Also, when there are a plurality of Ys1 When at least one of them has an ester structure, the heat resistance of the isocyanate component can be further improved.

[0321] (2)R 1 R 1 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms. R 1 The hydrocarbon group in is not particularly limited, and examples thereof include an alkyl group, an alkenyl group, and an alkynyl group. Among them, R 1 is preferably a hydrogen atom.

[0322] Specific examples of preferred triisocyanate compounds include, for example, 4-isocyanatomethyl-1,8-octamethylene diisocyanate (hereinafter sometimes referred to as "NTI", molecular weight 251) disclosed in International Publication No. 1996 / 17881 (Reference 1), 1,3,6-hexamethylene triisocyanate (hereinafter sometimes referred to as "HTI", molecular weight 209) disclosed in JP-A-57-198760 (Reference 2), bis(2-isocyanatoethyl) 2-isocyanatoglutarate (hereinafter sometimes referred to as "GTI", molecular weight 311) disclosed in JP-B-4-1033 (Reference 3), lysine triisocyanate (hereinafter sometimes referred to as "LTI", molecular weight 267) disclosed in JP-A-53-135931 (Reference 4), 4-isocyanatomethyl-1,8 and r-octamethylene diisocyanate (hereinafter sometimes referred to as "TTI"), etc. From the viewpoints of the migration property of the isocyanate component to the first uncured coating film and the reactivity of the isocyanate group, LTI, NTI, TTI or GTI is preferred, and LTI or TTI is more preferred.

[0323] The lower limit value of the molecular weight of the triisocyanate compound is preferably 139, more preferably 150, still more preferably 180, and particularly preferably 200. On the other hand, the upper limit value of the molecular weight of the triisocyanate compound is preferably 1000, more preferably 800, still more preferably 600, and particularly preferably 400. That is, the molecular weight of the triisocyanate compound is preferably 139 or more and 1000 or less, more preferably 150 or more and 800 or less, still more preferably 180 or more and 600 or less, and particularly preferably 200 or more and 400 or less. When the molecular weight of the triisocyanate compound is at least the above lower limit value, crystallization can be further suppressed, and when it is at most the above upper limit value, it is easier to achieve a lower viscosity.

[0324] The triisocyanate compound can be obtained, for example, by isocyanating amines such as amino acid derivatives, ether amines, and alkyl triamines. Examples of the amino acid derivative include 2,5-diaminovaleric acid, 2,6-diaminohexanoic acid, aspartic acid, glutamic acid, etc. These amino acid derivatives are diamine monocarboxylic acids or monoamine dicarboxylic acids. Therefore, the number of amino groups can be controlled by esterifying the carboxy group with an alkanolamine such as ethanolamine. Or, the number of amino groups can be controlled by esterifying the carboxy group with an alcohol such as methanol. The amine having the obtained ester structure can be made into a triisocyanate compound containing an ester structure by phosgenating the amine or the like.

[0325] Examples of the ether amine include "D403", a product name of Mitsui Chemicals Fine Chemicals Co., Ltd., which is a polyoxyalkylene triamine. These ether amines are triamines and can be made into a triisocyanate compound containing an ether structure by phosgenating the amine or the like.

[0326] Examples of the alkyl triamine include 4-aminomethyl-1,8-octanediamine. The alkyl triamine can be made into a triisocyanate containing only hydrocarbons by phosgenating the amine or the like.

[0327] The PI(T) component preferably contains a polyisocyanate component (B) in addition to the triisocyanate compound. Hereinafter, the polyisocyanate component (B) may be referred to as the "PI(B) component". The PI(B) component has an isocyanurate structure composed of one or more isocyanates selected from the group consisting of aliphatic isocyanates and alicyclic isocyanates. As the aliphatic isocyanate, those having 4 to 30 carbon atoms are preferred, and examples include tetramethylene-1,4-diisocyanate, pentamethylene-1,5-diisocyanate, hexamethylene diisocyanate (hereinafter sometimes referred to as "HDI"), 2,2,4-trimethylhexamethylene-1,6-diisocyanate, lysine diisocyanate, and the like, and the above triisocyanate. As the alicyclic isocyanate, those having 8 to 30 carbon atoms are preferred, and examples include isophorone diisocyanate (hereinafter sometimes referred to as "IPDI"), 1,3-bis(isocyanatomethyl)-cyclohexane, 4,4'-dicyclohexylmethane diisocyanate, and the like. The polyisocyanate is obtained from one or more selected from the group consisting of the above aliphatic isocyanates and alicyclic isocyanates and contains an isocyanurate structure. In general, the "isocyanurate structure" is a functional group derived from a polyisocyanate composed of three molecules of diisocyanate and is a group represented by the following formula (A).

[0328]

Chemical formula

[0329] As a method for producing a polyisocyanate containing an isocyanurate structure, for example, a method using a catalyst can be mentioned. The isocyanuration catalyst is not particularly limited, but generally those having basicity are preferred. For example, (1) hydroxides of tetraalkylammonium such as tetramethylammonium, tetraethylammonium, tetrabutylammonium; organic weak acid salts such as their acetates, octylates, myristates, benzoates, (2) hydroxides of hydroxyalkylammonium such as trimethylhydroxyethylammonium, trimethylhydroxypropylammonium, triethylhydroxyethylammonium, triethylhydroxypropylammonium; organic weak acid salts such as their acetates, octylates, myristates, benzoates, (3) metal salts of alkylcarboxylic acids such as acetic acid, caproic acid, octylic acid, myristic acid with metals such as tin, zinc, lead, (4) metal alcoholates such as sodium and potassium, (5) aminosilyl group-containing compounds such as hexamethylenedisilazane, (6) Mannich bases, (7) combined use of tertiary amines and epoxy compounds, (8) phosphorus compounds such as tributylphosphine, etc. can be mentioned. Among these, from the viewpoint of being less likely to generate unnecessary by-products, organic weak acid salts of quaternary ammonium are preferred, and organic weak acid salts of tetraalkylammonium are more preferred.

[0330] These catalysts may be diluted with a solvent or added together with a solvent from the viewpoint of catalyst miscibility. Examples of the solvent include 1-methylpyrrolidone, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether, methyl ethyl ketone, acetone, methyl isobutyl ketone, propylene glycol monomethyl ether acetate, ethanol, methanol, isopropanol, 1-propanol, isobutanol, 1-butanol, 2-ethylhexanol, cyclohexanol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, ethyl acetate, isopropyl acetate, butyl acetate, toluene, xylene, pentane, isopentane, hexane, isohexane, cyclohexane, solvent naphtha, mineral spirit, dimethylformamide, etc., and two or more thereof can be used in combination.

[0331] The isocyanuration reaction temperature is preferably 50°C or higher and 120°C or lower, more preferably 60°C or higher and 90°C or lower. By being 120°C or lower, coloring and the like can be effectively prevented, which is preferable.

[0332] The isocyanuration reaction is not particularly limited, but for example, it is stopped by the addition of an acidic compound such as phosphoric acid or an acidic phosphate ester.

[0333] The mass ratio of the triisocyanate compound to the PI(B) component, that is, triisocyanate compound:PI(B) component is preferably 4:6 to 9:1, more preferably 5:5 to 9:1. By being within the above range, the hardness of the coating film becomes high.

[0334] (Other isocyanate compounds) The isocyanate component contained in the coating composition may contain a polyisocyanate compound obtained from an isocyanate other than the triisocyanate compound and the PI(B) component, and an isocyanate compound other than the alicyclic isocyanate.

[0335] Examples of the "polyisocyanate compound obtained from an isocyanate other than the triisocyanate compound and the PI(B) component, and an isocyanate compound other than the alicyclic isocyanate" include a polyisocyanate obtained from an isocyanate other than the above aliphatic isocyanate or alicyclic isocyanate, and a polyisocyanate having a structure other than an isocyanurate structure obtained from an aliphatic isocyanate or alicyclic isocyanate.

[0336] Examples of the isocyanate other than the above aliphatic isocyanate or alicyclic isocyanate include aromatic isocyanates. Examples of aromatic isocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate (hereinafter sometimes referred to as "XDI"), and the like.

[0337] Examples of the structure other than the isocyanurate structure include at least one selected from the group consisting of an allophanate structure, an iminodioxadiazinedione structure, a biuret structure, and a urethane structure. Generally, the "allophanate structure" is formed by reacting the hydroxyl group of an alcohol with an isocyanate group and has a structure represented by the following formula (VI). Generally, the "iminodioxadiazinedione structure" is formed by reacting three isocyanate groups and has a structure represented by the following formula (VII). Generally, the "biuret structure" is formed by reacting three isocyanate groups with a biuretizing agent and has a structure represented by the following formula (VIII). Generally, the "urethane structure" is formed by reacting one isocyanate group with one hydroxyl group and has a structure represented by the following formula (IX).

[0338]

Chemical formula

[0339] Among these, from the viewpoint of weather resistance, it is preferable to contain an iminodioxadiazinedione structure, and from the viewpoint of workability due to low viscosity, it is preferable to contain an allophanate structure.

[0340] Examples of the "isocyanate compound other than triisocyanate" that can be contained in the coating paint composition include polyisocyanates of HDI having an isocyanurate structure, polyisocyanates of HDI having a uretdione structure, polyisocyanates of IPDI having an isocyanurate structure, and the like.

[0341] (2-1) Method for producing polyisocyanate · Method for producing polyisocyanate containing iminooxadiazinedione structure Examples of the method for producing polyisocyanate containing iminooxadiazinedione structure include a method using a catalyst. As the catalyst, for example, those shown in the following (i) to (x) can be used.

[0342] (i) (Poly)hydrogen fluoride represented by the general formula M[Fn] or the general formula M[Fn(HF)m] (wherein m and n are integers satisfying the relationship m / n > 0. M is an n-charged cation (mixture) or one or more radicals having a total valence of n); (ii) General formula R 11 -C(R 12 )2-C(O)O-, or the general formula R 21 =CR 22 -C(O)O- (wherein R 11 and R 21 are each independently a linear, branched or cyclic perfluoroalkyl group having 1 to 30 carbon atoms. R 12 and R 22Each is independently at least one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms which may contain a hetero atom, and an aryl group;), and a quaternary ammonium cation or a quaternary phosphonium cation, a compound consisting of; (iii) Hydroxides and organic weak acid salts of quaternary ammonium such as benzyltrialkylammonium and tetraalkylammonium; (iv) Hydroxides and organic weak acid salts of hydroxyalkylammonium; (v) Metal salts of alkylcarboxylic acids; (vi) Metal alcoholates such as sodium and potassium; (vii) Amino silyl group-containing compounds such as hexamethylenedisilazane; (viii) Mannich bases; (ix) Combined use of tertiary amines and epoxy compounds; (x) Phosphorus compounds such as tributylphosphine.

[0343] Specific examples of the (poly)hydrogen fluoride in (i) include, for example, tetramethylammonium fluoride hydrate, tetraethylammonium fluoride, and the like. Specific examples of the compound in (ii) include, for example, 3,3,3-trifluorocarboxylic acid, 4,4,4,3,3-pentafluorobutanoic acid, 5,5,5,4,4,3,3-heptafluoropentanoic acid, 3,3-difluoroprop-2-enoic acid, and the like.

[0344] Examples of the tetraalkylammonium include tetramethylammonium, tetraethylammonium, tetrabutylammonium, and the like. Examples of the hydroxyalkylammonium include trimethylhydroxyethylammonium, trimethylhydroxypropylammonium, triethylhydroxyethylammonium, triethylhydroxypropylammonium, and the like. Examples of the benzyltrialkylammonium include benzyltrimethylammonium, benzyltriethylammonium, benzyltributylammonium, and the like. Examples of the organic weak acid salt include acetate, octylate, myristate, benzoate, and the like.

[0345] Examples of the alkylcarboxylic acid include acetic acid, caproic acid, octylic acid, myristic acid, and the like. Examples of the metal contained in the metal salt include tin, zinc, lead, and the like.

[0346] Among these, from the viewpoint of availability, tetramethylammonium fluoride hydrate is preferable as the catalyst, and from the viewpoint of safety, the above (ii) is preferable. Further, from the viewpoint of being less likely to generate unnecessary by-products, an organic weak acid salt of quaternary ammonium is preferable, and an organic acid salt of benzyltrimethylammonium or an organic acid salt of tetramethylammonium is more preferable.

[0347] The lower limit value of the reaction temperature is preferably 40 °C, more preferably 50 °C, and even more preferably 55 °C. On the other hand, the upper limit value of the reaction temperature is preferably 120 °C, more preferably 100 °C, even more preferably 90 °C, and particularly preferably 80 °C. That is, the reaction temperature is preferably 40 °C or higher and 120 °C or lower, more preferably 50 °C or higher and 100 °C or lower, even more preferably 55 °C or higher and 90 °C or lower, and particularly preferably 55 °C or higher and 80 °C or lower. By setting the reaction temperature to be equal to or higher than the above lower limit value, it is possible to maintain a better reaction rate, and by setting it to be equal to or lower than the above upper limit value, coloring of the polyisocyanate can be more suppressed.

[0348] The reaction is not particularly limited, but for example, it can be stopped by adding an acidic compound such as phosphoric acid or an acidic phosphate ester.

[0349] · Method for producing an allophanate structure-containing polyisocyanate Examples of the method for producing the polyisocyanate containing an allophanate structure include a method of heating, a method using a catalyst, and the like. The allophanatization catalyst is not particularly limited, and for example, a zirconyl compound represented by the following general formula (VIII) (hereinafter sometimes referred to as "zirconyl compound (VIII)"), a zirconium alcoholate represented by the following general formula (IX) (hereinafter sometimes referred to as "zirconium alcoholate (IX)"), and the like can be used. These allophanatization catalysts can be used alone or in combination of two or more. Among these, as the allophanatization catalyst, the zirconyl compound (VIII) is preferable in order to obtain a polyisocyanate having a higher production ratio of the allophanate structure.

[0350]

Chemical formula

[0351] In the general formula (VIII), R 81 and R 82 are each independently a residue obtained by removing hydrogen of an organic carbonium oxy group, an alkoxy group, an alkyl group, a halogen group, or an inorganic acid.

[0352] In the present specification, the "organic carbonium oxy group" means a residue obtained by removing hydrogen of an organic carboxylic acid. That is, when both R 81 and R 82 in the above general formula (VII) are organic carbonium oxy groups, the zirconium compound is a zirconyl carboxylate. Examples of the organic carboxylic acid include aliphatic carboxylic acids, alicyclic carboxylic acids, unsaturated carboxylic acids, aromatic carboxylic acids, hydroxyl group-containing carboxylic acids, halogenated alkyl carboxylic acids, polybasic carboxylic acids, and the like. Examples of the polybasic carboxylic acid include dicarboxylic acids, tricarboxylic acids, and the like.

[0353] As the zirconyl compound (VIII), specifically, for example, zirconyl halide, zirconyl carboxylate, dialkyl zirconyl, zirconyl dialcoholate, zirconyl carbonate, zirconyl lead sulfate, zirconyl nitrate, etc. may be mentioned. Among them, zirconyl carboxylate is preferable.

[0354] Examples of the zirconyl carboxylate include saturated aliphatic carboxylates, saturated cyclic carboxylic acids, unsaturated aliphatic carboxylates, aromatic carboxylates, etc.

[0355] Examples of the saturated aliphatic carboxylate include zirconyl formate, zirconyl acetate, zirconyl propionate, zirconyl butanoate, zirconyl pentanoate, zirconyl hexanoate, zirconyl caproate, zirconyl octanoate, zirconyl 2-ethylhexanoate, zirconyl decanoate, zirconyl dodecanoate, zirconyl tetradecanoate, zirconyl pentadecanoate, etc.

[0356] Examples of the saturated cyclic carboxylic acid include zirconyl cyclohexanecarboxylate, zirconyl cyclopentanecarboxylate, zirconyl naphthenate, etc.

[0357] Examples of the unsaturated aliphatic carboxylate include zirconyl oleate, zirconyl linoleate, zirconyl linolenate, etc. Examples of the aromatic carboxylate include zirconyl benzoate, zirconyl toluate, zirconyl diphenylacetate, etc.

[0358] Among these, as the zirconyl carboxylate, from the viewpoint of easy industrial availability, zirconyl naphthenate, zirconyl 2-ethylhexanoate or zirconyl acetate is particularly preferable.

[0359]

Chemical formula

[0360] In the general formula (IX), R91 , R 92 , R 93 and R 94 are each independently an alkyl group, an alkenyl group or an alkynyl group.

[0361] Examples of the alcohol used as a raw material for zirconium alcoholate (IX) include saturated aliphatic alcohols, saturated cyclic aliphatic alcohols, unsaturated aliphatic alcohols, polyhydric alcohols, and the like.

[0362] Examples of the saturated aliphatic alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, iso-butanol, 1-pentanol, 2-pentanol, isoamyl alcohol, 1-hexanol, 2-hexanol, 1-heptanol, 1-octanol, 2-ethyl-1-hexanol, 3,3,5-trimethyl-1-hexanol, tridecanol, pentadecanol, and the like.

[0363] Examples of the saturated cyclic aliphatic alcohol include cyclohexanol and the like. Examples of the unsaturated aliphatic alcohol include ethanal, propanal, butanal, 2-hydroxyethyl acrylate, and the like.

[0364] Examples of the polyhydric alcohol include diols, triols, and the like. Examples of the diol include ethylene glycol, propanediol, 1,4-butanediol, 1,3-butanediol, 1,6-hexanediol, 1,4-hexanediol, 1,6-cyclohexanediol, 1,4-cyclohexanediol, and the like. Examples of the triol include glycerin and the like.

[0365] Among these, as the zirconium alcoholate (IX), from the viewpoint of easy industrial availability, tetra-n-propoxyzirconium, tetraisopropoxyzirconium, tetra-n-propoxyzirconium or tetra-n-butoxyzirconium is preferable.

[0366] The allophanatization reaction temperature is preferably 60°C or higher and 160°C or lower, more preferably 70°C or higher and 160°C or lower, and even more preferably 80°C or higher and 160°C or lower. By being below the above upper limit value, side reactions are less likely to occur, and there is a tendency to more effectively prevent the coloring of the obtained allophanate group-containing polyisocyanate.

[0367] The allophanatization reaction is not particularly limited, but can be stopped, for example, by adding an acidic compound such as a phosphoric acid acidic compound, sulfuric acid, nitric acid, chloroacetic acid, benzoyl chloride, sulfonic acid ester agent, or an ion exchange resin, chelating agent, chelating resin, etc.

[0368] Here, examples of the phosphoric acid acidic compound include phosphoric acid, pyrophosphoric acid, metaphosphoric acid, polyphosphoric acid, and alkyl esters thereof. Among them, it is preferable to use at least one of these phosphoric acid acidic compounds as a terminator.

[0369] · Method for producing a polyisocyanate containing a biuret structure Examples of the method for producing a polyisocyanate containing a biuret structure include a method using a biuretizing agent. The biuretizing agent is not particularly limited, and examples thereof include water, a monohydric tertiary alcohol, formic acid, hydrogen sulfide, an organic primary monoamine, an organic primary diamine, etc.

[0370] In this reaction, it is preferable that there are 6 moles or more of isocyanate groups per mole of the buret-forming agent, more preferably 10 moles or more, and even more preferably 10 moles or more and 80 moles or less. If it is at or above the above lower limit value, the polyisocyanate containing a buret structure obtained will have a lower viscosity more sufficiently. If it is at or below the above upper limit value, the curability can be maintained better when made into a coating composition.

[0371] In the buret-forming reaction, a solvent can be used. The solvent is preferably one that can dissolve the triisocyanate or diisocyanate and the buret-forming agent to form a homogeneous phase under the reaction conditions. As this solvent, an ethylene glycol-based solvent or a phosphoric acid-based solvent is preferable. These solvents can be used alone or in a mixture of two or more.

[0372] Specific examples of the ethylene glycol-based solvent include, for example, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-propyl ether acetate, ethylene glycol monoisopropyl ether acetate, ethylene glycol mono-n-butyl ether acetate, ethylene glycol diacetate, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol di-n-propyl ether, ethylene glycol diisopropyl ether, ethylene glycol di-n-butyl ether, ethylene glycol methyl ethyl ether, ethylene glycol methyl isopropyl ether, ethylene glycol methyl-n-butyl ether, ethylene glycol ethyl-n-propyl ether, ethylene glycol ethyl isopropyl ether, ethylene glycol ethyl-n-butyl ether, ethylene glycol-n-propyl-n-butyl ether, ethylene glycol isopropyl-n-butyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-propyl ether acetate, diethylene glycol monoisopropyl ether acetate, diethylene glycol mono-n-butyl ether acetate, diethylene glycol diacetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-propyl ether, diethylene glycol diisopropyl ether, diethylene glycol di-n-butyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl isopropyl ether, diethylene glycol methyl-n-propyl ether, diethylene glycol methyl-n-butyl ether, diethylene glycol ethyl isopropyl ether, diethylene glycol ethyl-n-propyl ether, diethylene glycol ethyl-n-butyl ether, diethylene glycol-n-propyl-n-butyl ether, diethylene glycol isopropyl-n-butyl ether, and the like. Among these, as the ethylene glycol-based solvent, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol diacetate, or diethylene glycol dimethyl ether is preferable.

[0373] Specific examples of the phosphoric acid-based solvent include trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, and the like. Among them, as the phosphoric acid-based solvent, trimethyl phosphate or triethyl phosphate is preferable.

[0374] The burette reaction temperature is preferably 70°C or higher and 200°C or lower, more preferably 90°C or higher and 180°C or lower. By being below the above upper limit value, coloring and the like can be more effectively prevented.

[0375] The NCO / OH of the coating paint composition is preferably 1.0 to 2.5, more preferably 1.2 to 2.0, and most preferably 1.4 to 1.8. When the NCO / OH is within the above range, the hardness of the coating film laminate becomes good.

[0376] [Other Components] The primer coating composition and the coating paint composition may further contain other components in addition to the above isocyanate component and the above hydroxyl group-containing resin component. Examples of other components include unsaturated bond-containing compounds, inert compounds, metal atoms, basic amino compounds, carbon dioxide, halogen atoms, and the like. These components may be contained alone or in combination of two or more.

[0377] (Unsaturated Bond-Containing Compound) As the unsaturated bond-containing compound, a compound having an unsaturated bond between carbon-carbon, an unsaturated bond between carbon-nitrogen, or an unsaturated bond between carbon-oxygen is used. From the viewpoint of the stability of the compound, the unsaturated bond is preferably a double bond, more preferably a double bond between carbon-carbon (C═C) or a double bond between carbon-oxygen (C═O). Further, the carbon atoms constituting the compound can be carbon atoms bonded to three or more atoms. Generally, the double bond between carbon-carbon may be a double bond between carbon-carbon constituting an aromatic ring, but the unsaturated bond contained in the unsaturated bond-containing compound in the resin composition of the present embodiment does not include a double bond between carbon-carbon constituting an aromatic ring. Examples of the compound having a double bond between carbon-oxygen include carbonate derivatives. Examples of the carbonate derivatives include urea compounds, carbonic acid esters, N-unsubstituted carbamic acid esters, N-substituted carbamic acid esters, and the like.

[0378] (Inert compound) The inert compound is classified into, for example, the following Compounds A to G. Specifically, hydrocarbon compounds are classified into Compounds A and B, ether compounds and sulfide compounds are classified into the following Compounds C to E, halogenated hydrocarbon compounds are classified into the following Compound F, and silicon-containing hydrocarbon compounds, silicon-containing ether compounds, and silicon-containing sulfide compounds are classified into the following Compound G, respectively. Note that Compounds A to G listed here do not contain an unsaturated bond other than an aromatic ring and do not include the compounds having the above-described unsaturated bond.

[0379] Compound A: A linear, branched, or cyclic aliphatic hydrocarbon compound. Compound B: An aromatic hydrocarbon compound which may be substituted with an aliphatic hydrocarbon group. Compound C: A compound having an ether structure or a sulfide group and an aliphatic hydrocarbon group, and a compound in which the same or different aliphatic hydrocarbon compounds are bonded via an ether structure or a sulfide group. Compound D: A compound having an ether structure or a sulfide group and an aromatic hydrocarbon group, which is a compound in which the same or different aromatic hydrocarbon compounds are bonded via an ether structure or a sulfide group. Compound E: A compound having an ether structure or a sulfide group, an aliphatic hydrocarbon group, and an aromatic hydrocarbon group. Compound F: A halide in which at least one hydrogen atom constituting an aliphatic hydrocarbon compound or at least one hydrogen atom constituting an aromatic hydrocarbon compound is substituted with a halogen atom. Compound G: A compound in which some or all of the carbon atoms of the above Compounds A to E are substituted with silicon atoms.

[0380] (Metal atom) The metal atom may exist as a metal ion or as a single metal atom. It may be one kind of metal atom or a combination of plural kinds of metal atoms. As the metal atom, a metal atom having a valence of 2 or more and 4 or less is preferable, and among them, one or more metals selected from iron, cobalt, nickel, zinc, tin, copper, and titanium are more preferable.

[0381] (Basic amino compound) The basic amino compound is a derivative of ammonia, and examples thereof include a compound in which one of its hydrogen atoms is substituted with an alkyl group or an aryl group (primary), a compound in which two are substituted (secondary), a compound in which all three are substituted (tertiary), etc. Among them, as the basic amino compound, a secondary or tertiary amino compound is preferable, and an aliphatic amine, an aromatic amine, a heterocyclic amine, or a basic amino acid is more preferable.

[0382] (Carbon dioxide) Carbon dioxide may be the dissolved isocyanate content at normal pressure, or may be dissolved in a pressure vessel under a pressurized state. Since using carbon dioxide containing moisture may cause hydrolysis of the isocyanate, it is preferable to control the moisture content contained in the carbon dioxide as necessary.

[0383] (Halogen atom) From the viewpoint of preventing coloring, the halogen atom content contained in the first coating composition and the second coating composition is preferably 1.0×10 2 ppm by mass or less. The halogen atom is not particularly limited, but at least one of a chlorine atom and a bromine atom is preferable, and at least one ion or compound selected from the group consisting of chloride ions, bromide ions, hydrolyzable chlorine, and hydrolyzable bromine is more preferable. Examples of the hydrolyzable chlorine include carbamoyl chloride compounds in which hydrogen chloride is added to an isocyanate group, and examples of the hydrolyzable bromine include carbamoyl bromide compounds in which hydrogen bromide is added to an isocyanate group.

[0384] [Melamine-based curing agent] The first coating composition and the second coating composition may further contain a melamine-based curing agent as required. Examples of the melamine-based curing agent include a fully alkyl type, a methylol type alkyl, and an imino group type alkyl.

[0385] [Organic solvent] Also, the above isocyanate component, the above hydroxyl group-containing resin component, the first coating composition, and the second coating composition can all be used by mixing with an organic solvent. As the organic solvent, those having no functional group that reacts with a hydroxyl group and an isocyanate group are preferable. Also, those compatible with the isocyanate component are preferable. As such an organic solvent, those generally used as a paint solvent can be used. Specifically, for example, ester compounds such as butyl acetate, ether compounds, ketone compounds, aromatic compounds, ethylene glycol dialkyl ether-based compounds, polyethylene glycol dicarboxylate-based compounds, hydrocarbon-based solvents, aromatic solvents such as xylene, etc. can be mentioned.

[0386] [Other additives] In addition, the first coating composition and the second coating composition may further contain various additives used in the relevant technical field, such as catalysts for promoting curing, pigments, leveling agents, antioxidants, ultraviolet absorbers, light stabilizers, plasticizers, surfactants, etc., as long as the effects of the present embodiment are not impaired according to the purpose and application.

[0387] Examples of the catalyst for promoting curing include metal salts, tertiary amines, and the like. Examples of the metal salts include dibutyltin dilaurate, tin 2-ethylhexanoate, zinc 2-ethylhexanoate, cobalt salts, and the like. Examples of the tertiary amines include triethylamine, pyridine, methylpyridine, benzyldimethylamine, N,N-dimethylcyclohexylamine, N-methylpiperidine, pentamethyldiethylenetriamine, N,N'-ethylene piperazine, N,N'-dimethylpiperazine, and the like.

[0388] In the primer coating composition, the lower limit value of the content of other components can be 1.0 mass ppm or more, 3.0 mass ppm, 5.0 mass ppm, or 10 mass ppm based on the content of the BPI component. On the other hand, the upper limit value of the content of other components can be 1.0×10 4 mass ppm, 5.0×10 3 mass ppm, 3.0×10 3 mass ppm, or 1.0×10 3 mass ppm based on the content of the BPI component. That is, in the primer coating composition, the content of other components can be 1.0 mass ppm or more and 1.0×10 4 mass ppm or less, 3.0 mass ppm or more and 5.0×10 3 mass ppm or less, 5.0 mass ppm or more and 3.0×10 3It can be made to be below a certain mass ppm, and can be 10 mass ppm or more and 1.0×10 3 It can be made to be below a certain mass ppm.

[0389] In the coating paint composition, the lower limit value of the content of other components can be 1.0 mass ppm or more, can be 3.0 mass ppm, can be 5.0 mass ppm, and can be 10 mass ppm, based on the content of the triisocyanate compound. On the other hand, the upper limit value of the content of other components can be 1.0×10 4 mass ppm, can be 5.0×10 3 mass ppm, can be 3.0×10 3 mass ppm, and can be 1.0×10 3 mass ppm. That is, in the coating paint composition, the content of other components can be 1.0 mass ppm or more and 1.0×10 4 mass ppm or less, can be 3.0 mass ppm or more and 5.0×10 3 mass ppm or less, can be 5.0 mass ppm or more and 3.0×10 3 mass ppm or less, and can be 10 mass ppm or more and 1.0×10 3 mass ppm or less, from the viewpoints of preventing coloring during long-term storage and improving long-term storage stability, based on the content of the triisocyanate compound.

[0390] <Coated film laminate> One aspect of the coated film laminate of the present embodiment is a coated film laminate in which a base layer and a coating layer are laminated in this order. One aspect of the coated film laminate of the present embodiment is a coated film laminate in which a base layer and a coating layer are laminated in this order, and the base layer includes a first coated film layer and a second coated film layer. That is, it is a coated film laminate in which the first coated film layer, the second coated film layer, and the coating layer are laminated in this order.

[0391] Fig. 1 shows an aspect of the coating film laminate of the present embodiment. Fig. 1 shows a coating film laminate 1 formed on an object to be coated 10. The coating film laminate 1 has a base layer 11 and a coating layer 12 laminated in this order.

[0392] (Object to be coated 10) The object to be coated 10 is not particularly limited, and examples include molded articles formed from materials such as metals (steel plates, surface-treated steel plates, etc.), plastics, woods, and inorganic materials. Further, the shape of these molded articles is not particularly limited, and for example, those with a small thickness such as films, sheets, and boards may be used, and those with a large thickness such as cylinders and three-dimensional structures may also be used. Also, hollow ones such as tubes may be used.

[0393] Further, the object to be coated 10 may be a coating film. Examples of the coating film include those obtained by coating and curing a main agent such as polyol and a curing agent such as (block) polyisocyanate and melamine, as well as uncured coating films before curing. In the method for forming the coating film laminate described later, it is preferable that the object to be coated is an uncured coating film, and by curing it together with the first uncured coating film, the second uncured coating film, and the third uncured coating film by heating, the uncured coating film as the object to be coated can be made into a cured coating film.

[0394] Further, the object to be coated 10 is preferably an outer panel of an automobile in which a metal member and an attached plastic member are integrally combined.

[0395] The coating film laminate 1 has a base layer 11 and a coating layer 12 laminated in this order. The base layer 11 is a layer that directly contacts the object to be coated 10, and the coating layer 12 is formed on the base layer 11 and is the outermost layer of the coating film laminate 1.

[0396] Fig. 2 shows an aspect of the coating film laminate of the present embodiment. Fig. 2 shows a coating film laminate 2 formed on an object to be coated 10. The coating film laminate 2 has a base layer 11 including a first coating film layer 11b and a second coating film layer 11a, and a coating layer 12 laminated in this order.

[0397] The first coating film layer 11b is formed from the above-described first primer coating composition, and the second coating film layer 11a is formed from the above-described second primer coating composition. In one aspect of the coating film laminate 2, the first coating film layer 11b is a crosslinked layer, and the second coating film layer 11a is a colored layer.

[0398] In one aspect of the coating film laminate 2, an arbitrary resin layer may be provided between the first coating film layer 11b and the second coating film layer 11a. The arbitrary resin layer is, for example, a layer composed of polyethylene terephthalate.

[0399] (Use) The coating film laminate of the present embodiment is useful, for example, as a primer layer (undercoat layer), an intermediate coat layer, and a topcoat layer for materials such as metals (steel plates, surface-treated steel plates, etc.), plastics, woods, and inorganic materials. It is also useful as a laminate for imparting decorative properties, weather resistance, acid resistance, rust prevention properties, chipping resistance, etc. to pre-coated metals including rust-proof steel plates and automotive painting.

[0400] (Modification example of coating film laminate) FIG. 3 shows a coating film laminate which is a modification example of the coating film laminate. The coating film 3B shown in FIG. 3 includes a substrate 10 and a base layer 11. FIG. 4 shows a coating film laminate which is a modification example of the coating film laminate. The coating film 4B shown in FIG. 4 includes a substrate 10 and a base layer 11 having a first coating film layer 11b and a second coating film layer 11a.

[0401] <Manufacturing method of coating film laminate> One aspect of the present invention is a method for manufacturing a coating film laminate in which a base layer and a coating layer are laminated in this order on a substrate.

[0402] When the coating film laminate of the present embodiment has a two-layer structure of a base layer and a coating layer, the method for manufacturing the coating film laminate includes a step of applying the base coating composition of the present embodiment onto an object to be coated to obtain an uncured coating film, a step of applying a coating composition onto the uncured coating film to obtain an uncured coating film, and a step of heating the uncured coating film and the uncured top coating film at a temperature of 40°C or higher and 140°C or lower to cure them simultaneously.

[0403] It is preferable that the base layer of the coating film laminate manufactured by the method for manufacturing the coating film laminate of the present embodiment includes a first coating film layer and a second coating film layer.

[0404] The method for manufacturing the coating film laminate of the present embodiment includes a step of applying the base coating composition of the present embodiment onto an object to be coated to obtain a first uncured coating film, a step of further applying the base coating composition onto the first uncured coating film to obtain a second uncured coating film, a step of applying a coating composition onto the second uncured coating film to obtain an uncured coating film, and a step of heating the first uncured coating film, the second uncured coating film, and the uncured top coating film at a temperature of 40°C or higher and 140°C or lower to cure them simultaneously.

[0405] The base coating composition for forming the first uncured coating film and the base coating composition for forming the second coating film may have the same composition or different compositions. In the present embodiment, it is preferable that the base coating composition for forming the first uncured coating film and the base coating composition for forming the first uncured coating film have different compositions from the viewpoint of improving the color tone of the layer coating film laminate.

[0406] Preferably, the first base coating composition is applied to form the first uncured coating film, and preferably, the second base coating composition is applied to form the second uncured coating film. The coating composition of the present embodiment is used to form the uncured coating film.

[0407] The manufacturing method of the coating film laminate of the present embodiment preferably includes a step of coating the above-described base coating composition as the first coating composition on an object to be coated to obtain a first coating film, a step of coating a second coating composition on the obtained first coating film to obtain a second coating film, and a step of coating a third coating composition on the obtained second coating film to obtain a third coating film.

[0408] One aspect of the manufacturing method of the coating film laminate of the present embodiment includes a step of coating the above-described base coating composition as the first coating composition on an object to be coated to obtain a first uncured coating film, a step of coating a second coating composition on the obtained first uncured coating film to obtain a second uncured coating film, and a step of coating a third coating composition on the obtained second uncured coating film to obtain a third uncured coating film.

[0409] In one aspect of the manufacturing method of the coating film laminate of the present embodiment, the first uncured coating film, the second uncured coating film, and the third uncured coating film are simultaneously cured by heating at 40°C or higher and 140°C or lower to form a coating film laminate composed of three layers of the first coating film, the second coating film, and the third coating film.

[0410] By using the above-described base coating composition as the first coating composition, a coating film laminate excellent in hardness, water resistance, and chipping resistance (appearance) can be manufactured even when cured at a low temperature of 40°C or higher and 140°C or lower.

[0411] When the third uncured coating film is laminated on the first uncured coating film and the second uncured coating film, a part of the components in the third coating composition migrates to the first uncured coating film and the second uncured coating film, and a concentration gradient of the polyisocyanate component is formed in the first uncured coating film and the second uncured coating film from the side of the third uncured coating film toward the side of the object to be coated while migrating. For this reason, the adhesion between the first uncured coating film, the second uncured coating film, and the third uncured coating film is improved.

[0412] Furthermore, when the object to be coated is an uncured coating film, the first coating composition and the second coating composition migrate to the uncured coating film as the object to be coated, and a precoat layer is formed on the surface of the object to be coated. The hydroxyl group-containing resin component also exists in the precoat layer. Therefore, the first uncured coating film and the second uncured coating film are cured in a state of being adhered to the object to be coated through the precoat layer. Furthermore, it is preferable that the polyisocyanate component that has migrated from the third uncured coating film via the first uncured coating film and the second uncured coating film also exists in the precoat layer. In the presence of the polyisocyanate component, the adhesion of the coating film can be further enhanced by curing the precoat layer, the first uncured coating film, the second uncured coating film, and the third uncured coating film together.

[0413] Here, the object to be coated, which is an uncured coating film, preferably contains a polyol as a main component and further contains a melamine-based curing agent. Examples of the melamine-based curing agent include those similar to the materials described in the "melamine-based curing agent" described later.

[0414] 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 can be formed by laminating them on an object to be coated such as a substrate or a coating film using methods such as roll coating, curtain flow coating, spray coating, bell coating, and electrostatic coating, respectively.

[0415] In the manufacturing method of the present embodiment, after obtaining the third uncured coating film, the heating temperature for simultaneously curing the first uncured coating film, the second uncured coating film, and the third uncured coating film is preferably 40°C or higher, more preferably 60°C or higher, and most preferably 80°C or higher. Also, the heating temperature is preferably 140°C or lower, more preferably 120°C or lower.

[0416] The above upper limit value and lower limit value of the heating temperature can be arbitrarily combined. Examples of the combination include 40°C or higher and 140°C or lower, 40°C or higher and 120°C or lower, 60°C or higher and 140°C or lower, 60°C or higher and 120°C or lower, 80°C or higher and 140°C or lower, and 80°C or higher and 120°C or lower.

[0417] The heating time is preferably 10 minutes or more, more preferably 15 minutes or more. Also, the heating time is preferably 40 minutes or less, more preferably 35 minutes or less. The above upper and lower limit values of the heating time can be arbitrarily combined. Examples of the combination are 10 minutes or more and 40 minutes or less, 15 minutes or more and 35 minutes or less. By setting the heating temperature and the heating time within the above ranges, the curability of the coating film and the yellowing resistance of the coating film laminate become better.

[0418] In the manufacturing method of the present embodiment, after obtaining the first uncured coating film and the second uncured coating film, or before coating the first uncured coating film and the second uncured coating film using the uncured coating film as a base material, short-time preheating can be performed. The preheating is a low-temperature short-time drying process at about 70°C or more and 80°C or less, and about 1 minute or more and 5 minutes or less, and can be performed under conditions where the first uncured coating film and the second uncured coating film do not cure.

[0419] In one aspect of the manufacturing method of the coating film laminate of the present embodiment, the first coating composition, the second coating composition, and the third coating composition preferably have different compositions from each other.

[0420] The first coating film, the second coating film, and the third coating film may each consist of only one layer, or may consist of a plurality of layers of two or more.

[0421] The first coating film, the second coating film, and the third coating film preferably each have a film thickness after curing of 10 μm or more, more preferably 15 μm or more. On the other hand, the film thickness after curing is preferably 60 μm or less, more preferably 50 μm or less for each. The film thickness after curing is, for example, 10 μm or more and 60 μm or less, 15 μm or more and 50 μm or less for each. By having the film thickness after curing within the above range, the durability of the coating film laminate can be further improved.

Examples

[0422] Hereinafter, the present embodiment will be described in more detail with specific examples and comparative examples. However, the present embodiment is not limited to the following examples and comparative examples as long as it does not exceed the gist. The physical properties of the polyisocyanate component and the evaluation of the coating film in the examples and comparative examples were measured and evaluated as follows. Unless otherwise specified, "parts" and "%" mean "parts by mass" and "mass%".

[0423] <Measurement method> (Physical property) Isocyanate group content (NCO group content) Using the base coating compositions obtained in the examples and comparative examples as samples, the isocyanate group content was measured using the method shown below. (1) 1 g of the sample was taken into a 200 mL Erlenmeyer flask, and 20 mL of toluene was added to the flask to dissolve the sample. (2) Then, 20 mL of a 2.0 N di-n-butylamine·toluene solution was added to the above flask and allowed to stand for 15 minutes. (3) 70 mL of 2-propanol was added to the above flask and dissolved to obtain a solution. (4) The solution obtained in (3) above was titrated with 1 mol / L hydrochloric acid to determine the sample titration volume. (5) Even when the sample was not added, the measurement was carried out in the same manner as in (1) to (3) above to obtain the blank titration volume. From the sample titration volume and the blank titration volume obtained above, the isocyanate group content was calculated using the formula shown below.

[0424] Isocyanate group content [mass%] =(Blank titration volume - Sample titration volume) × 42 / [Sample mass (1 g) × 1000] × 100

[0425] (Physical property) Detection method of specific structure The molar ratios of the iminooxadiazinedione group, uretdione group, allophanate group, and isocyanurate group were determined by measuring 13C NMR using Biospin Avance600 (trade name) manufactured by Bruker. The specific measurement conditions were as follows.

[0426] 13 C-NMR apparatus: AVANCE600 (manufactured by Bruker) Cryo Probe (manufactured by Bruker) Cryo Probe CPDUL 600S3-C / H-D-05Z Resonance frequency: 150 MHz Concentration: 60 wt / vol% Shift reference: CDCl3 (77 ppm) Number of integrations: 10,000 times Pulse program: zgpg30 (proton complete decoupling method, waiting time 2 sec)

[0427] (Physical properties) Number average molecular weight and weight average molecular weight The number average molecular weight and weight average molecular weight are the number average molecular weight and weight average molecular weight based on polystyrene by gel permeation chromatography (GPC) measurement using the following apparatus. To measure the number average molecular weight of the polyisocyanate, the polyisocyanate before blocking with the blocking agent was used as the measurement sample. Regarding the weight average molecular weight, the base coat composition or the polyhydric hydroxy compound was used as the measurement sample as it is. The measurement conditions are shown below.

[0428] (Measurement conditions) Apparatus: HLC-802A manufactured by Tosoh Corporation Column: One G1000HXL manufactured by Tosoh Corporation One G2000HXL One G3000HXL Carrier: Tetrahydrofuran Detection method: Differential refractometer

[0429] (Physical properties) Average number of isocyanate groups The average isocyanate group number (average NCO number) of the polyisocyanate was determined by the following formula. In the formula, "Mn" is the number average molecular weight of the polyisocyanate, and "NCO content" is the isocyanate group content of the polyisocyanate. The values calculated above were used. Average isocyanate group number = (Mn × NCO content × 0.01) / 42

[0430] <Synthesis of Polyisocyanate> [Synthesis Example 1] (Synthesis of Polyisocyanate P-1) Into a four-necked flask equipped with a thermometer, a stirring blade, and a reflux condenser, under a nitrogen stream, 100 parts by mass of HDI and 5.2 parts by mass of a polyester polyol (manufactured by Daicel Chemical Industries, Ltd., "Placcel 303" (trade name), average functional group number: 3, number average molecular weight 300) derived from a trivalent alcohol and ε-caprolactone were charged. While stirring, the temperature inside the reactor was maintained at 88°C for 1 hour to carry out a urethanization reaction. Thereafter, the temperature inside the reactor was maintained at 62°C, and tetramethylammonium caprylate, an isocyanurate formation catalyst, was added. Phosphoric acid was added to stop the reaction when the yield reached 51% by mass. After filtering the reaction solution, unreacted HDI was removed using a thin-film evaporator to obtain an isocyanurate-type polyisocyanate (hereinafter sometimes referred to as "polyisocyanate P-1"). The NCO content of the obtained polyisocyanate P-1 was 18.8% by mass, the number average molecular weight was 1180, and the average isocyanate group number was 5.3. Further, 1H-NMR analysis was performed on the obtained polyisocyanate P-1, and it was confirmed that an isocyanurate group was present.

[0431] [Synthesis Example 2] (Synthesis of Hydrophilic Compound-Modified Polyisocyanate P-2) In a four-necked flask equipped with a thermometer, a stirring blade, and a reflux condenser tube, under a nitrogen stream, 100 parts by mass of polyisocyanate P-1, 13 parts by mass of dipropylene glycol dimethyl ether (DPDM), 15 parts by mass of methoxypolyethylene glycol (MPG-081, ethylene oxide repeating unit: 15, manufactured by Nippon Emulsifier Co., Ltd.) (an amount that becomes 5 mol% with respect to 100 mol% of the isocyanate groups of polyisocyanate P-2), and 0.08 parts by mass of 2-ethylhexyl acid phosphate (JP-508T, manufactured by Johoku Chemical Industry Co., Ltd.) were mixed and stirred at 120 °C for 2 hours to obtain a hydrophilic compound-modified polyisocyanate P-2. The NCO content of the obtained polyisocyanate P-2 was 14.0% by mass, and the average number of isocyanate groups was 5.0.

[0432] [Synthesis Example 3] (Synthesis of Block Polyisocyanate BL-1) In a four-necked flask equipped with a thermometer, a stirring blade, and a reflux condenser tube, under a nitrogen stream, 100 parts by mass of the polyisocyanate P-2 obtained in Synthesis Example 2 and 63.9 parts by mass of diisopropyl malonate (102 mol% with respect to 100 mol% of the NCO groups) were charged, and further, dipropylene glycol dimethyl ether (DPDM) was added to prepare a solution with a solid content of 60% by mass. Next, while stirring, 1.0 part by mass of a methanol solution containing sodium methylate (28% by mass with respect to the total mass of the solution) was added dropwise, and then the external bath was adjusted so that the solution temperature became 55 °C, and a blocking reaction was carried out at 55 °C for 5 hours to obtain a block polyisocyanate intermediate with a solid content of 60% by mass. Thereafter, 75 parts by mass of 2-methyl-2-butanol (250 mol% with respect to the blocked isocyanate groups) was added, and the generated isopropyl alcohol was removed by distillation under normal pressure while reacting at 80 °C for 3 hours. Thereafter, further, at 60 °C under reduced pressure (50 kPa), isopropanol and 2-methyl-2-butanol were distilled off, and finally, dipropylene glycol dimethyl ether (DPDM) was added to adjust the solid content to 60% by mass to obtain a block polyisocyanate component BL-1.

[0433] [Synthesis Example 4] (Synthesis of Block Polyisocyanate BL-2) Into a four-necked flask equipped with a thermometer, a stirring blade, and a reflux condenser, under a nitrogen stream, 100 parts by mass of the polyisocyanate P-2 obtained in Synthesis Example 2 and 63.9 parts by mass of diisopropyl malonate (102 mol% based on 100 mol% of NCO groups) were charged. Further, dipropylene glycol dimethyl ether (DPDM) was added to prepare a solution with a solid content of 60% by mass. Next, while stirring, 1.0 part by mass of a methanol solution containing sodium methylate (28% by mass based on the total mass of the solution) was added dropwise. Then, the external bath was adjusted so that the solution temperature reached 55°C, and a blocking reaction was carried out at 55°C for 5 hours to obtain a block polyisocyanate intermediate with a solid content of 60% by mass. Thereafter, 75 parts by mass of 2-methyl-2-butanol (250 mol% based on the blocked isocyanate groups) was added, and the generated isopropyl alcohol was removed by distillation under normal pressure while reacting at 125°C for 3 hours. Thereafter, further, at 60°C under reduced pressure (50 kPa), isopropanol and 2-methyl-2-butanol were distilled off, and finally, dipropylene glycol dimethyl ether (DPDM) was added to adjust the solid content to 60% by mass to obtain a block polyisocyanate component BL-1.

[0434] [Synthesis Example 5] (Synthesis of Block Polyisocyanate BL-3) Into a four-necked flask equipped with a thermometer, a stirring blade, and a reflux condenser, under a nitrogen stream, 100 parts by mass of the polyisocyanate P-2 obtained in Synthesis Example 2 and 63.9 parts by mass of diisopropyl malonate (102 mol% relative to 100 mol% of NCO groups) were charged. Further, dipropylene glycol dimethyl ether (DPDM) was added to prepare a solution with a solid content of 60% by mass. Next, while stirring, 1.0 part by mass of a methanol solution containing sodium methylate (28% by mass relative to the total mass of the solution) was added dropwise. Then, the external bath was adjusted so that the solution temperature became 55°C, and a blocking reaction was carried out at 55°C for 5 hours to obtain a blocked polyisocyanate intermediate with a solid content of 60% by mass. Thereafter, 75 parts by mass of 2-methyl-2-butanol (250 mol% relative to the blocked isocyanate groups) was added and reacted at 80°C for 3 hours. Then, further, at 60°C under reduced pressure (50 kPa), isopropanol and 2-methyl-2-butanol were distilled off, and finally, dipropylene glycol dimethyl ether (DPDM) was added to adjust the solid content to 60% by mass, thereby obtaining a blocked polyisocyanate component BL-1.

[0435] [Synthesis Example 6] (Synthesis of Blocked Polyisocyanate BL-4) Into a four-necked flask equipped with a thermometer, a stirring blade, and a reflux condenser, under a nitrogen stream, 100 parts by mass of the polyisocyanate P-1 obtained in Synthesis Example 1, 0.01 part by mass of 2-ethylhexyl acid phosphate (manufactured by Johoku Chemical Industry Co., Ltd., "JP-508T" (trade name)), 11.6 parts by mass of methoxypolyethylene glycol (MPG-081, number of ethylene oxide repeating units: 15, manufactured by Nippon Emulsion Co., Ltd.) (an amount corresponding to 4 mol% based on 100 mol% of the isocyanate groups of the polyisocyanate P-1), and 19.7 parts by mass of dipropylene glycol dimethyl ether (DPDM) were mixed, and the reaction was carried out at 120 °C for 3 hours. The reaction solution was cooled to 40 °C, and diisopropyl malonate was charged so as to be 96 mol% based on 100 mol% of the isocyanate groups of the polyisocyanate P-1. Further, dipropylene glycol dimethyl ether (DPDM) was added to prepare a solution having a solid content of 70% by mass. Then, while stirring, 1.2 parts by mass of a methanol solution containing sodium methylate (28% by mass based on the total mass of the solution) was added dropwise, and then the external bath was adjusted so that the solution temperature became 55 °C, and a blocking reaction was carried out at 55 °C for 5 hours to obtain an intermediate of a blocked polyisocyanate component having a solid content of 70% by mass. Thereafter, 161 parts by mass of 2-methyl-2-butanol (400 mol% based on the blocked isocyanate groups) was added, and the generated isopropyl alcohol was removed by distillation under normal pressure, and the reaction was carried out at 80 °C for 3 hours. Thereafter, further, 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, thereby obtaining a blocked polyisocyanate component BL-4.

[0436] [Synthesis Example 7] (Production of Blocked Polyisocyanate Component BL-5) Into a four-necked flask equipped with a thermometer, a stirring blade, and a reflux condenser, under a nitrogen stream, 100 parts by mass of the polyisocyanate P-1 obtained in Synthesis Example 1, 0.01 part by mass of 2-ethylhexyl acid phosphate (manufactured by Johoku Chemical Industry Co., Ltd., "JP-508T" (trade name)), 87.1 parts by mass of methoxypolyethylene glycol (MPG-081, number of ethylene oxide repeating units: 15, manufactured by Nippon Emulsion Co., Ltd.) (an amount that becomes 30 mol% with respect to 100 mol% of the isocyanate groups of the polyisocyanate P-1), and 33.0 parts by mass of dipropylene glycol dimethyl ether (DPDM) were mixed, and the reaction was carried out at 120 °C for 3 hours. The reaction solution was cooled to 40 °C, diisopropyl malonate was charged so as to be 70 mol% with respect to 100 mol% of the isocyanate groups of the polyisocyanate P-1, and further, dipropylene glycol dimethyl ether (DPDM) was added to prepare a solid content of 60% by mass. Then, while stirring, 1.5 parts by mass of a methanol solution containing sodium methylate (28% by mass with respect to the total mass of the solution) was added dropwise, and then the external bath was adjusted so that the solution temperature became 55 °C, and the external bath was adjusted so that the solution temperature became 55 °C, and the blocking reaction was carried out at 55 °C for 6 hours or more. After confirming the disappearance of the peak of the isocyanate group by infrared spectroscopy (IR), the blocked polyisocyanate component BL-5 was obtained.

[0437] [Synthesis Example 8] (Production of Blocked Polyisocyanate Component BL-6) Into a four-necked flask equipped with a thermometer, a stirring blade, and a reflux condenser, under a nitrogen stream, 100 parts by mass of the polyisocyanate P-1 obtained in Synthesis Example 1, 0.01 part by mass of 2-ethylhexyl acid phosphate (manufactured by Johoku Chemical Industry Co., Ltd., "JP-508T" (trade name)), 46.4 parts by mass of methoxypolyethylene glycol (MPG-081, number of ethylene oxide repeating units: 15, manufactured by Nippon Emulsion Co., Ltd.) (an amount that becomes 16 mol% with respect to 100 mol% of the isocyanate groups of the polyisocyanate P-1), and 33.0 parts by mass of dipropylene glycol dimethyl ether (DPDM) were mixed, and the reaction was carried out at 120°C for 3 hours. The reaction solution was cooled to 40°C, diisopropyl malonate was charged so as to be 84 mol% with respect to 100 mol% of the isocyanate groups of the polyisocyanate P-1, and further, dipropylene glycol dimethyl ether (DPDM) was added to prepare a solution having a solid content of 60% by mass. Then, while stirring, 1.5 parts by mass of a methanol solution containing sodium methylate (28% by mass with respect to the total mass of the solution) was added dropwise, and then the external bath was adjusted so that the solution temperature became 55°C, and the external bath was adjusted so that the solution temperature became 55°C, and the blocking reaction was carried out at 55°C for 6 hours or more. After confirming the disappearance of the peak of the isocyanate group by infrared spectroscopy (IR), the blocked polyisocyanate component BL-6 was obtained.

[0438] [Synthesis Example 9] (Production of Blocked Polyisocyanate Component BL-7) Into a four-necked flask equipped with a thermometer, a stirring blade, and a reflux condenser tube, under a nitrogen stream, 100 parts by mass of the polyisocyanate P-1 obtained in Synthesis Example 1, 0.01 part by mass of 2-ethylhexyl acid phosphate (manufactured by Johoku Chemical Industry Co., Ltd., "JP-508T" (trade name)), 30.5 parts by mass of methoxypolyethylene glycol (MPG-081, number of ethylene oxide repeating units: 15, manufactured by Nippon Emulsion Co., Ltd.) (an amount that becomes 10.5 mol% with respect to 100 mol% of the isocyanate groups of the polyisocyanate P-1), and 33.0 parts by mass of dipropylene glycol dimethyl ether (DPDM) were mixed, and the reaction was carried out at 120°C for 3 hours. The reaction solution was cooled to 40°C, diisopropyl malonate was charged so as to be 84 mol% with respect to 100 mol% of the isocyanate groups of the polyisocyanate P-1, and further, dipropylene glycol dimethyl ether (DPDM) was added to prepare a solution having a solid content of 60% by mass. Next, while stirring, 1.5 parts by mass of a methanol solution containing sodium methylate (28% by mass with respect to the total mass of the solution) was added dropwise, then the external bath was adjusted so that the solution temperature became 55°C, and the external bath was adjusted so that the solution temperature became 55°C, and the blocking reaction was carried out at 55°C for 6 hours or more. After confirming the disappearance of the peak of the isocyanate group by infrared spectroscopy (IR), the blocked polyisocyanate component BL-7 was obtained.

[0439] [Synthesis Example 10] (Production of Block Polyisocyanate Component BL-8) Into a four-necked flask equipped with a thermometer, a stirring blade, and a reflux condenser tube, under a nitrogen stream, 80 parts by mass of the blocked polyisocyanate component BL-4 obtained in Synthesis Example 6 and 20 parts by mass of the blocked polyisocyanate component BL-5 obtained in Synthesis Example 7 were charged, the external bath was adjusted so that the solution temperature became 40°C, and they were mixed at 40°C for 1 hour or more to obtain the blocked polyisocyanate component BL-8.

[0440] [Synthesis Example 11] (Production of Block Polyisocyanate Component BL-9) Into a four-necked flask equipped with a thermometer, a stirring blade, and a reflux condenser tube, under a nitrogen stream, 57 parts by mass of the blocked polyisocyanate component BL-4 obtained in Synthesis Example 6 and 43 parts by mass of the blocked polyisocyanate component BL-6 obtained in Synthesis Example 7 were charged. The external bath was adjusted so that the solution temperature became 40°C, and the mixture was stirred at 40°C for 1 hour or more to obtain the blocked polyisocyanate component BL-9.

[0441] [Synthesis Example 12] (Production of Blocked Polyisocyanate Component BL-10) Into a four-necked flask equipped with a thermometer, a stirring blade, and a reflux condenser tube, under a nitrogen stream, 20 parts by mass of the blocked polyisocyanate component BL-4 obtained in Synthesis Example 6 and 80 parts by mass of the blocked polyisocyanate component BL-7 obtained in Synthesis Example 7 were charged. The external bath was adjusted so that the solution temperature became 40°C, and the mixture was stirred at 40°C for 1 hour or more to obtain the blocked polyisocyanate component BL-10.

[0442] [Synthesis Example 13] (Production of Blocked Polyisocyanate Component BL-11) Into a four-necked flask equipped with a thermometer, a stirring blade, and a reflux condenser tube, under a nitrogen stream, 100 parts by mass of the polyisocyanate P-1 obtained in Synthesis Example 1-1, 0.01 part by mass of 2-ethylhexyl acid phosphate (manufactured by Johoku Chemical Industry Co., Ltd., "JP-508T" (trade name)), 26.7 parts by mass of methoxypolyethylene glycol (MPG-081, number of ethylene oxide repeating units: 15, manufactured by Nippon Emulsion Co., Ltd.) (an amount that becomes 9.2 mol% with respect to 100 mol% of the isocyanate groups of the polyisocyanate P-1), and 33.0 parts by mass of dipropylene glycol dimethyl ether (DPDM) were mixed, and the reaction was carried out at 120°C for 3 hours. The reaction solution was cooled to 40°C, and diisopropyl malonate was charged so as to be 84 mol% with respect to 100 mol% of the isocyanate groups of the polyisocyanate P-1. Further, dipropylene glycol dimethyl ether (DPDM) was added to prepare a solution having a solid content of 60% by mass. Next, while stirring, 1.5 parts by mass of a methanol solution containing sodium methylate (28% by mass with respect to the total mass of the solution) was added dropwise, and then the external bath was adjusted so that the solution temperature became 55°C. The external bath was adjusted so that the solution temperature became 55°C, and the blocking reaction was carried out at 55°C for 6 hours or more. After confirming the disappearance of the peak of the isocyanate group by infrared spectroscopy (IR), the blocked polyisocyanate component X-4 was obtained.

[0443] Details of each blocked polyisocyanate component obtained in the examples and comparative examples are shown in Table 1 below.

[0444]

Table 1

[0445] [Synthesis Example 14] (Synthesis of Polyisocyanate P-3) 1,8 - octamethylenediamine (hereinafter sometimes referred to as "triamine") 1060 g was dissolved in 1500 g of methanol in a four - necked flask equipped with a stirrer, a thermometer, and a gas inlet tube. While cooling, 1800 mL of 35 mass% concentrated hydrochloric acid was gradually added dropwise thereto. Subsequently, methanol and water were removed under reduced pressure and concentrated, and dried at 60 °C / 5 mmHg for 24 hours to obtain white solid triamine hydrochloride. 650 g of the obtained triamine hydrochloride was suspended as fine powder in 5000 g of o - dichlorobenzene, and the temperature of the reaction solution was raised while stirring. Subsequently, when the reaction solution reached 100 °C, phosgene was started to be blown in at a rate of 200 g / hour, and the temperature was further raised. Then, when the reaction solution reached 180 °C, the temperature was maintained as it was, and phosgene was continuously blown in for 12 hours. Subsequently, after removing dissolved phosgene and the solvent under reduced pressure, vacuum distillation was performed to obtain 420 g of colorless and transparent NTI having a boiling point of 161 °C or higher and 163 °C or lower / 1.2 mmHg. The NCO content of NTI was 50.0 mass%.

[0446] [Synthesis Example 15] (Synthesis of Polyisocyanate P - 4) Into a four-necked flask equipped with a stirrer, a thermometer, and a gas inlet tube, 122.2 g of ethanolamine, 100 ml of o-dichlorobenzene, and 420 ml of toluene were placed. Hydrogen chloride gas was introduced under ice cooling to convert ethanolamine into its hydrochloride. Next, 182.5 g of lysine hydrochloride was added, and the reaction solution was heated to 80 °C to dissolve the ethanolamine hydrochloride. Hydrogen chloride gas was introduced to form lysine dihydrochloride. Further, hydrogen chloride gas was passed through at a rate of 20 to 30 ml / min, and the reaction solution was heated to 116 °C and maintained at this temperature until no more water distilled off. The resulting reaction mixture was recrystallized in a mixed solution of methanol and ethanol to obtain 165 g of lysine β-aminoethyl ester trihydrochloride. 100 g of this lysine β-aminoethyl ester trihydrochloride was suspended as a fine powder in 1200 ml of o-dichlorobenzene, and while stirring, the temperature of the reaction solution was raised. When it reached 120 °C, phosgene was introduced at a rate of 0.4 mol / hour and held for 10 hours, and then the temperature was raised to 150 °C. The suspension was almost completely dissolved. After cooling, it was filtered, and the dissolved phosgene and the solvent were distilled off under reduced pressure, and then vacuum distilled to obtain 80.4 g of a colorless and transparent LTI with a boiling point of 155 - 157 °C / 0.022 mmHg. The NCO content of this product was 47.1 wt%.

[0447] Polyisocyanate P-5 and 6 P-5: TKA-100 (trade name), manufactured by Asahi Kasei, NCO group content: 21.8 P-6: MFA-100 (resin component of MFA-75B, trade name), manufactured by Asahi Kasei, NCO group content: 18.4 [Synthesis Example 16] (Synthesis of Polyisocyanate P-7) The inside of a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen blowing tube, and a dropping funnel was made into a nitrogen atmosphere. 30 parts by mass of the polyisocyanate P-3 obtained in Synthesis Example 14 and 70 parts by mass of the polyisocyanate P-5 were mixed at room temperature to obtain polyisocyanate P-7.

[0448] [Synthesis Example 17] (Synthesis of Polyisocyanate P-8) The inside of a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser tube, a nitrogen injection tube, and a dropping funnel was made into a nitrogen atmosphere, and 50 parts by mass of polyisocyanate P-3 obtained in Synthesis Example 14 and 50 parts by mass of polyisocyanate P-5 were mixed at room temperature to obtain polyisocyanate P-8.

[0449] [Synthesis Example 18] (Synthesis of Polyisocyanate P-9) The inside of a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser tube, a nitrogen injection tube, and a dropping funnel was made into a nitrogen atmosphere, and 30 parts by mass of polyisocyanate P-4 obtained in Synthesis Example 15 and 70 parts by mass of polyisocyanate P-5 were mixed at room temperature to obtain polyisocyanate P-9.

[0450] [Synthesis Example 19] (Synthesis of Polyisocyanate P-10) The inside of a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser tube, a nitrogen injection tube, and a dropping funnel was made into a nitrogen atmosphere, and 50 parts by mass of polyisocyanate P-4 obtained in Synthesis Example 15 and 50 parts by mass of polyisocyanate P-5 were mixed at room temperature to obtain polyisocyanate P-10.

[0451] [Synthesis Example 20] (Synthesis of Polyisocyanate P-11) The inside of a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser tube, a nitrogen injection tube, and a dropping funnel was made into a nitrogen atmosphere, and 30 parts by mass of polyisocyanate P-3 obtained in Synthesis Example 14 and 70 parts by mass of polyisocyanate P-6 were mixed at room temperature to obtain polyisocyanate P-11.

[0452] [Synthesis Example 21] (Synthesis of Polyisocyanate P-12) The inside of a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser tube, a nitrogen injection tube, and a dropping funnel was made into a nitrogen atmosphere, and 50 parts by mass of polyisocyanate P-3 obtained in Synthesis Example 14 and 50 parts by mass of polyisocyanate P-6 were mixed at room temperature to obtain polyisocyanate P-12.

[0453] [Synthesis Example 22] (Synthesis of Polyisocyanate P-13) The inside of a four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen inlet tube, and dropping funnel was made into a nitrogen atmosphere, and 30 parts by mass of polyisocyanate P-4 obtained in Synthesis Example 15 and 70 parts by mass of polyisocyanate P-6 were mixed at room temperature to obtain polyisocyanate P-13. [Synthesis Example 23] (Synthesis of Polyisocyanate P-14) The inside of a four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen inlet tube, and dropping funnel was made into a nitrogen atmosphere, and 50 parts by mass of polyisocyanate P-4 obtained in Synthesis Example 15 and 50 parts by mass of polyisocyanate P-6 were mixed at room temperature to obtain polyisocyanate P-14.

[0454] (Manufacture of Coated Film Laminate) [Example 1] (Preparation of Sample Coated Plate T-a1) (Manufacture of the First Paint Composition) Weighed 87.9 parts of deionized water, 245.0 parts of titanium oxide pigment (English name: Ti-Pure R-902+, manufactured by Chemours), 17.2 parts of a wetting dispersant for water systems (product name: BYK-190, manufactured by BYK), and 0.7 part of an antifoaming agent (product name: Tego902W) into a container, and stirred at 2700 rpm for 120 minutes using a propeller blade.

[0455] After stirring, 650 parts of an acrylic polyol aqueous dispersion (product name: Setaqua6510, hydroxyl value per resin: 138 mgKOH / g, manufactured by Allnex) was added, and stirring was continued at 1500 rpm for 30 minutes. While stirring, 2.0 parts of a silicone-based antifoaming agent (product name: BYK-024, manufactured by BYK), 0.7 part of an antifoaming agent (Tego902W), and 1.0 part of a surface conditioner (product name: BYK-346, manufactured by BYK) were added, and stirring was carried out for 15 minutes. Further, 3.0 parts of a viscosity modifier (product name: Acrysol RM-8W, manufactured by Dow Chemical) was added, and stirring was carried out for 15 minutes.

[0456] Next, the block polyisocyanate component BL-1 obtained in Synthesis Example 3 was added at a ratio such that the ratio (NCO / OH) of the molar amount of isocyanate groups to the molar amount of hydroxyl groups in the acrylic polyol aqueous dispersion was 0.3. Further, 2-(dimethylamino)ethanol and deionized water were added at a ratio such that the solid content in the pH-adjusted paint composition was 43% by mass of deionized water, and the mixture was stirred at 600 rpm for 10 minutes using a propeller blade to obtain a first paint composition 1-a1 having a viscosity of 50 seconds as measured by Ford Cup No. 4 at pH 8.0 and 20°C.

[0457] (Production of the second paint composition 2-1) As the second paint composition 2-1, an aqueous base-2 (black) (product name: nax E-CUBE WB aqueous color base (silent black), manufactured by Nippon Paint Co., Ltd.) was used.

[0458] (Production of the third paint composition) In advance, an acrylic polyol (manufactured by Allnex, "SETALUX D A 665 BA / X (trade name)") and a polyisocyanate P-7 obtained in Synthesis Example 14 as the polyisocyanate component (B) were blended at a molar ratio of isocyanate groups / hydroxyl groups (NCO / OH) of 1.4. As additives, BYK-331 was blended at 0.10% by mass / resin content, TINUVIN 292 was blended at 1.0% by mass / resin content, and TINUVIN 384-2 was blended at 1.5% by mass / resin content, and diluted with propylene glycol monomethyl ether acetate / solvent naphtha (mass ratio 50 / 50) to a spray viscosity of 27 seconds (ISO 5 cup) to prepare a third paint composition.

[0459] (Production of the three-layer coating laminate) As the substrate, a cationic electrodeposited steel sheet was used, and the first paint composition, which is a primer paint composition, was spray-coated to a dry film thickness of 18 μm and allowed to stand at room temperature for 5 minutes to form a first uncured coating film. Thereafter, as the second coating composition, an aqueous base-2 (black sapphire color) was spray-coated on the first uncured coating film to a dry film thickness of 13 μm, left standing at room temperature for 5 minutes, and then preheated at 70 °C for 5 minutes to obtain a laminate in which the substrate, the first uncured coating film, and the second uncured coating film were laminated in this order.

[0460] Next, the third coating composition produced by the above method was spray-coated on the second uncured coating film after preheating to a dry film thickness of 40 μm. Thereafter, after drying at 80 °C for 30 minutes, it was dried in an atmosphere of 3 °C and 50% humidity for 24 hours to obtain a sample coated plate T-a1 which is a three-layer laminate.

[0461] [Examples 2 to 15 and Comparative Examples 3 and 4] (Preparation of Sample Coated Plates T-a2 to T-a15 and T-b3, 4) A sample coated plate having a three-layer coating film laminate was obtained in the same manner as in Example 8, except that the type of the blocked polyisocyanate component (A) of the first coating composition and the polyisocyanate component (B) of the third coating composition were changed to the materials shown in Tables 2 and 3.

[0462] [Examples 16 and 17] (Preparation of Sample Coated Plates T-a16 and 17) A sample coated plate having a three-layer coating film laminate was obtained in the same manner as in Example 1, except that the type of the blocked polyisocyanate component (A) of the first coating composition and the polyisocyanate component (B) of the third coating composition were changed to the materials shown in Table 3, and the second coating composition 2-2 in which the blocked polyisocyanate component (A) described later was mixed was used as the second coating composition.

[0463] (Production of the Second Coating Composition 2-2 Used in Examples 16 and 17) To the water-based base-2 (black) (product name: nax E-CUBE WB water-based color base (silent black), manufactured by Nippon Paint Co., Ltd.), the blocked polyisocyanate component BL-1 produced above was added at a ratio of 2% by mass, and then deionized water was added at a ratio such that the solid content became 25% by mass. Stirring was carried out at 600 rpm for 10 minutes using a propeller blade to obtain the second coating composition 2-2.

[0464] [Examples 18, 19] (Preparation of sample coated plates T-a18, 19) The type of the blocked polyisocyanate component (A) of the first coating composition and the polyisocyanate component (B) of the third coating composition were changed to the materials shown in Table 3, and a sample coated plate having a three-layer coating film laminate was obtained in the same manner as in Example 1, except that the second coating composition 2-3 in which the blocked polyisocyanate component (A) described below was mixed was used as the second coating composition.

[0465] (Production of the second coating composition 2-3 used in Examples 18 and 19) To the water-based base-2 (black) (product name: nax E-CUBE WB water-based color base (silent black), manufactured by Nippon Paint Co., Ltd.), the blocked polyisocyanate component BL-1 produced above was added at a ratio of 4% by mass, and then deionized water was added at a ratio such that the solid content became 25% by mass. Stirring was carried out at 600 rpm for 10 minutes using a propeller blade to obtain the second coating composition 2-3.

[0466] [Comparative Examples 1, 2] (Preparation of sample coated plates T-b1, 2) Sample coated plates were obtained in the same manner as in Example 1, except that the coating compositions described below were used as the third and first coating compositions.

[0467] (Production of the third coating composition used in Comparative Example 1) In advance, an acrylic polyol (manufactured by Allnex, "SETALUX D A 665 BA / X (product name)") was blended with additives BYK-331 at 0.10% by mass / resin content, TINUVIN 292 at 1.0% by mass / resin content, and TINUVIN 384-2 at 1.5% by mass / resin content, and diluted with propylene glycol monomethyl ether acetate / solvent naphtha (mass ratio 50 / 50) at a ratio such that the spray viscosity was 27 seconds (ISO 5 cup) to prepare a third paint composition.

[0468] (Manufacture of the first paint composition used in Comparative Example 2) Weighed 87.9 parts of deionized water, 245.0 parts of titanium oxide pigment (English name: Ti-Pure R-902+, manufactured by Chemours), 17.2 parts of a wetting dispersant for water-based systems (product name: BYK-190, manufactured by BYK), and 0.7 part of an antifoaming agent (product name: Tego902W) into a container, and stirred for 120 minutes at 2700 rpm using a propeller blade. After stirring, 650 parts of an acrylic polyol aqueous dispersion (product name: Setaqua6510, hydroxyl value per resin: 138 mgKOH / g, manufactured by Allnex) was added, and stirring was continued for 30 minutes at 1500 rpm. While stirring, 2.0 parts of a silicone-based antifoaming agent (product name: BYK-024, manufactured by BYK), 0.7 part of an antifoaming agent (Tego902W), and 1.0 part of a surface conditioner (product name: BYK-346, manufactured by BYK) were added, and stirring was continued for 15 minutes. Further, 3.0 parts of a viscosity modifier (product name: Acrysol RM-8W, manufactured by Dow Chemical) was added, and stirring was continued for 15 minutes. Next, 146 parts of a melamine resin (manufactured by Ornex Japan Co., Ltd., product name "Cymel 325", an imino group type methylated melamine resin) was added. Further, deionized water was added in such a ratio that the solid content in the pH-adjusted paint composition became 43% by mass, and stirring was carried out for 10 minutes at 600 rpm using a propeller blade to obtain the first paint composition 1-b2 with a pH of 8.0.

[0469] [Evaluation] (Coating film hardness: Martens hardness) Using the Martens hardness measuring device HM2000S from Fisher Instruments, a Vickers square pyramid (material: diamond) indenter was pressed into the sample coated plates obtained in each example and comparative example under an atmosphere of 23°C and 50% relative humidity with a test force of 2000 mN, a required time for test force application of 10 seconds, and a holding time for test force of 5 seconds, and the Martens hardness (N / mm 2 ) was measured. According to the following evaluation criteria, the Martens hardness was calculated from the relationship between the test force and the indentation depth of the indenter, and the average value of three points was taken for evaluation.

[0470] (Evaluation criteria) ◎: 70 times or more 〇: 60 times or more and less than 69 times △: 50 times or more and less than 59 times ×: Less than 49 times

[0471] (Water resistance) The sample coated plates obtained in each example and comparative example were immersed in warm water at 40°C for 10 days, pulled out and gently wiped to remove moisture, and the appearance of the coating film was evaluated.

[0472] (Evaluation criteria) ◎: No blisters 〇: 5 blisters or less and width less than 1 cm △: 6 blisters or more and width less than 1 cm ×: 6 blisters or more and width 1 cm or more

[0473] For each obtained sample coated plate, various physical properties were measured using the methods described above, and the coating film hardness and water resistance were evaluated. The results are shown in Tables 2 and 3.

[0474] (Finished appearance) Using BYK WaveScan, the DOI (distinctness of image) of the sample coated plates obtained in each example and comparative example was measured. According to the following evaluation criteria, the finished appearance: DOI was evaluated.

[0475] (Evaluation criteria) ◎: 95 or more ○: 90 or more and less than 95 △: Less than 90

[0476]

Table 2

[0477]

Table 3

[0478] As shown in the above results, in Examples 1 to 19 using the primer coating composition of this embodiment, even when cured at 80°C, a coating film laminate having good hardness and water resistance was obtained. From the results of Comparative Examples 1 to 4, it was confirmed that when the primer coating composition does not satisfy the specific composition of the present invention, hardness and water resistance cannot be achieved simultaneously when cured at 80°C.

Explanation of Reference Numerals

[0479] 1, 2: Coating film laminate, 10: Object to be coated, 11: Primer layer, 12: Coating layer, 11a: Second coating film layer, 11b: First coating film layer, 3B, 4B: Coated object

Claims

1. A primer coating composition for forming a coating film laminate on an object to be coated, wherein the primer coating composition contains a blocked polyisocyanate component and a hydroxyl group-containing resin component, the blocked polyisocyanate component contains a blocked polyisocyanate derived from a polyisocyanate and one or more blocking agents, and the blocked polyisocyanate component contains a structural unit represented by the following general formula (I): A primer coating composition. 【Chemical 1】 (In general formula (I), R １１ , R １２ and R １３ are each independently an alkyl group which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group, and the total number of carbon atoms 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 which may contain one or more substituents selected from the group consisting of a hydroxy group and an amino group. The wavy line represents a bond.)

2. The primer coating composition according to claim 1, wherein the polyisocyanate is a polyisocyanate derived from one or more diisocyanates selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates.

3. The primer coating composition according to claim 1 or 2, wherein the average number of isocyanate groups of the polyisocyanate contained in the blocked polyisocyanate component is 3.5 or more.

4. A coating paint composition for forming a coating film laminate on an object to be coated, containing a polyisocyanate component (B), wherein the polyisocyanate component (B) contains a triisocyanate compound represented by the following general formula (II): A coating paint composition. [Chemical 2] (In the general formula (II), a plurality of Y １ are each independent and are a divalent hydrocarbon group having 1 to 20 carbon atoms which may contain either or both of an ester structure and an ether bond, and a plurality of Y １ may be the same or different from each other, and R １ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms.)

5. A coating film laminate in which a primer layer and a coating layer are laminated in this order, wherein the primer layer is formed from the primer coating composition according to claim 1 or 2, and the coating layer is formed from the coating paint composition according to claim 4: A coating film laminate.

6. The coating film laminate according to claim 5, wherein the primer layer includes a first coating film layer and a second coating film layer.

7. A method for manufacturing a coating film laminate in which a primer layer and a coating layer are laminated in this order on an object to be coated, wherein the primer layer includes a first coating film layer and a second coating film layer, a step of applying a primer coating composition on the object to be coated to obtain a first uncured coating film, a step of further applying a primer coating composition on the first uncured coating film to obtain a second uncured coating film, a step of applying a coating paint composition on the second uncured coating film to obtain an uncured topcoat film, and a step of heating the first uncured coating film, the second uncured coating film, and the uncured topcoat film at a temperature of 40°C or higher and 140°C or lower to cure them simultaneously. A method for manufacturing a coating film laminate, wherein the primer coating composition is the primer coating composition according to claim 1 or 2. The method for producing a coating film laminate is the coating paint composition according to claim 4.

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