JP2002320910A - Coating method for curing composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for coating a composition capable of forming a cured film excellent in blocking resistance and freeze damage resistance in the case of using a curing composition containing a polymer having maleimide group. SOLUTION: The present invention is a coating method characterized by such a way that the curing composition containing the polymer having maleimide group is coated on a base material and an active energy lay is irradiated thereto, and the coating layer is cured by sunlight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating a curable composition, and a cured film obtained by the method of the present invention has excellent blocking resistance, frost damage resistance, weather resistance and the like. It can be awarded in the technical field of coating such as a coating agent.

[0002]

2. Description of the Related Art Sizing materials are mainly used for architectural purposes, but since they are used outdoors, their surfaces are required to have weather resistance. For the purpose of improving the weather resistance, there is an increasing number of so-called clear top specifications in which the surface of the sizing material is painted with a clear paint. However, the sizing material is usually stored in a stack after production, but the conventional clear paint film is
There is a demand for a coating film that easily causes blocking, that is, sizing materials stick to each other, and has excellent blocking resistance.

On the other hand, the present inventors have found that a composition containing a polymer having a maleimide group has excellent weather resistance as a film obtained and is effective as a coating material. Patent applications have been filed (Japanese Patent Application No. 11-344275, Japanese Patent Application No. 11-362080, etc.).

The present inventors have studied the application of the composition containing the polymer having a maleimide group to a top coat of a sizing material. However, after application of the composition, the composition is cured by irradiation with active energy rays such as ultraviolet rays. In this case, although the blocking resistance is excellent, the physical properties of the cured film, especially the freeze-thaw resistance such as freeze-thaw properties are insufficient. There was a case. The present inventors have been eager to find a method of coating a composition capable of forming a cured film having excellent blocking resistance and frost damage resistance when a curable composition containing a polymer having a maleimide group is used. The study was conducted.

[0005]

As a result of various studies, the present inventors have found that the cause of insufficient frost damage resistance is that although the cured film surface after active energy ray irradiation is sufficiently cured, The present inventors have found that unreacted maleimide groups may remain in the cured film, and found that the above problem can be solved by applying a specific coating method, thus completing the present invention. Hereinafter, the present invention will be described in detail. In this specification, an acryloyl group or a methacryloyl group is referred to as a (meth) acryloyl group, acrylic acid or methacrylic acid is referred to as (meth) acrylic acid, and acrylate or methacrylate is referred to as (meth) acrylate.

[0006]

DETAILED DESCRIPTION OF THE INVENTION 1. Polymer having maleimide group
In the coating method of the present invention, a composition containing a polymer having a maleimide group (hereinafter referred to as a maleimide polymer) is used. Hereinafter, the maleimide polymer will be described.

[0007] 1) Maleimide polymer [0007] The maleimide group in the maleimide polymer includes various groups, and a group represented by the following formula (1) is preferable.

[0008]

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However, in the formula (1), R ¹ and R ² are each independently a hydrogen atom or an alkyl group, one of them is a hydrogen atom and the other is an alkyl group, or each is bonded to form a carbon ring. Is the group that forms.

R¹And R^TwoAs independent accounts
Alkyl groups, or groups that combine to form a carbon ring
Is preferred. Alkyl groups having 4 or less carbon atoms
Is preferred. A group that combines to form a carbocyclic ring,
Is a group -CH_TwoCH_TwoCH _Two-Or group -CH_TwoCH_Two
CH_TwoCH_TwoIs preferred, particularly preferably the group -CH_TwoC
H_TwoCH_TwoCH_Two-.

[0011] The molecular weight of the maleimide polymer may be appropriately determined according to the purpose.
It is 100 to 1,000,000, and more preferably 10,000 to 500,000. If this value is less than 1000, the weather resistance and water resistance may be reduced, while if it exceeds 1,000,000, the film formability may be reduced. In the present invention, the number average molecular weight is a value obtained by converting the molecular weight measured by gel permeation chromatography (hereinafter abbreviated as GPC) using tetrahydrofuran as a solvent, based on the molecular weight of polyethylene.

As the maleimide polymer in the present invention, various polymers having a maleimide group can be used, and those obtained by various methods can be used. For example, the following production methods 1) -1 to 5 can be mentioned.

1) A method of polymerizing a compound having a maleimide group and an ethylenically unsaturated group (hereinafter referred to as a maleimide monomer). 1) A method in which a compound having a maleimide group and an isocyanate group (hereinafter referred to as an isocyanate-based maleimide compound) is added to a prepolymer containing a 2- hydroxyl group. 1) A method of adding a compound having a maleimide group and a carboxyl group (hereinafter referred to as a carboxyl maleimide compound) to an epoxy group-containing prepolymer. 1) A method of adding a compound having a maleimide group and a hydroxyl group (hereinafter referred to as a hydroxyl maleimide compound) to a prepolymer containing -4 isocyanate group. 1) A method in which a hydroxyl maleimide compound is added to a prepolymer containing -5 acid anhydride groups. Among these production methods, production method 1) -1 is preferred because the production of the polymer is easy. Hereinafter, each manufacturing method will be described.

(1) Manufacturing Method 1) -1 First, the manufacturing method 1) -1 will be described. Examples of the maleimide monomer used in the production method 1) -1 include a compound having an ethylenically unsaturated group and a maleimide group represented by the above formula (1) (hereinafter referred to as an imide unsaturated compound).

In the imide unsaturated compound, examples of the ethylenically unsaturated group include a vinyl group and a (meth) acryloyl group, and a (meth) acryloyl group is preferable.

In the imide unsaturated compound, the compound represented by the formula (1)
R ¹ and R ² in the above are each independently an alkyl group or each bonded to each other in that it is excellent in its own polymerizability or copolymerizability with another ethylenically unsaturated group-containing monomer. Groups forming a carbocycle are preferred. The alkyl group preferably has 4 or less carbon atoms. Furthermore, the group which forms a carbocyclic ring by bonding to each other is preferable because the production of the imide unsaturated compound is easy, the yield is excellent, and the obtained copolymer has excellent water resistance. preferably, group -CH ₂ CH ₂ CH ₂ -, or a group -CH ₂ CH ₂
CH ₂ CH ₂ — is preferred, particularly preferably the group —CH ₂ C
H ₂ CH ₂ CH ₂ —.

The imide unsaturated compound is represented by the following formula (2)
The imide (meth) acrylate represented by is preferred.

[0018]

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However, in the formula (2), R ¹ and R ² are the same groups as described above. R ³ is an alkylene group, R ⁴ is a hydrogen atom or a methyl group, and n is an integer of 1 to 6. formula
Among (2), those having n of 1 to 2 are preferable, and those having 1 are more preferable. R ³ has 1 carbon atom
To 6, and more preferably an ethylene group and a propylene group.

In the production method 1) -1, in addition to the maleimide monomer, if necessary, other ethylenically unsaturated monomers copolymerizable with these monomers (hereinafter referred to as other monomers) May be used. Other ethylenically unsaturated monomers include (meth) acrylates other than imide (meth) acrylate, (meth) acrylic acid, (meth) acrylonitrile, vinyl acetate, vinyl propionate, styrene, and α-methylstyrene, And vinyltrimethoxysilane, vinyltriethoxysilane, γ-
Examples include ethylenically unsaturated monomers having an alkoxysilyl group such as methacryloyloxy, propyltrimethoxysilane, and γ-methacryloyloxypropyltriethoxysilane.

As the (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate,
Propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate and stearyl (meth) Alicyclic (meth) acrylates such as alkyl (meth) acrylate such as acrylate, cyclohexyl (meth) acrylate and isobornyl (meth) acrylate; aryl (meth) acrylate such as benzyl (meth) acrylate; 2-methoxyethyl (meth) ) Acrylate and 2-
Alkoxyalkyl (meth) acrylates such as ethoxyethyl (meth) acrylate, and hydroxyethyl (meth) acrylate and hydroxypropyl (meth)
Examples include hydroxyalkyl (meth) acrylate such as acrylate, perfluoroalkyl (meth) acrylate, glycidyl (meth) acrylate, and N, N-diethylaminoethyl (meth) acrylate.

Among these, preferred monomers from the viewpoints of copolymerizability and film properties include alkyl (meth) acrylates having an alkyl group having 1 to 8 carbon atoms, (meth) acrylic acid, styrene, carbon Hydroxyalkyl (meth) acrylates having 2 to 3 alkylene groups, glycidyl (meth) acrylate, and the like are mentioned. As a preferable monomer from the viewpoint of weather resistance and the like, cyclohexyl (meth) acrylate is mentioned.

The proportion of the maleimide monomer and the other monomer constituting the polymer is 1 to 40 parts by mass, preferably 4 to 20 parts by mass, and the proportion of the other monomer is 60 to 99 parts by mass. Parts, preferably 80 to 96 parts by weight. When the amount of the maleimide monomer is less than 1 part by mass, the blocking resistance after irradiation with active energy rays is insufficient, and the crosslinking density after curing with sunlight is low, and the physical properties such as the water resistance of the cured film may be inferior. If the amount exceeds 40 parts by mass, the crosslinked density becomes too high and the cured film may become brittle.

The means for polymerizing the maleimide monomer in the production method 1) -1 can be produced by polymerization according to a conventional method such as a solution polymerization method, a high emulsion polymerization method and a warm continuous polymerization method.

In the case of production by a solution polymerization method, the monomer can be obtained by dissolving a monomer to be used in an organic solvent, adding a thermal polymerization initiator, and stirring with heating.

In the case of production by an emulsion polymerization method, the monomers to be used are dispersed in an aqueous medium using an emulsifier,
A method of heating and stirring in the presence of a polymerization initiator, and dispersing the monomer using an emulsifier to form an aqueous emulsion, and adding the aqueous emulsion to an aqueous medium while the presence of the polymerization initiator is present. A method of stirring under heating can be given below.

In each case, a chain transfer agent can be used to control the molecular weight of the polymer. Examples of the thermal polymerization initiator to be used include peroxides, azo compounds, and redox initiators that generate radical species by heat.

The kind and ratio of the polymerization initiator, the polymerization temperature to be applied and the method of supplying the monomer may be appropriately selected depending on the monomer to be used and the purpose. As the polymerization temperature, a polymerization temperature suitable for a commonly used polymerization initiator is employed.

In the emulsion polymerization, emulsifiers such as sodium dialkylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium polyoxyethylene alkylphenyl ether sulfate and sodium alkyldiphenyl ether disulfonate may be used depending on the required properties and the like. Examples include anionic surfactants and nonionic surfactants such as polyoxyethylene higher alcohol ethers and polyoxyethylene alkylphenyl ethers.

As the emulsifier, it is preferable to use a radical polymerizable surfactant from the viewpoint that the obtained copolymer has excellent water resistance. When a radically polymerizable surfactant is used as an emulsifier, it is easily incorporated into the copolymer as a third component of the copolymer when the monomer is subjected to emulsion polymerization. For the radical polymerizable surfactant,
JP-B-46-12472, JP-B-56-2965
7, JP-A-56-28208, JP-A-56-28208
Japanese Patent Application Laid-Open Nos. 1227697, 62-100502, and 2-162287, etc., and are commercially available as latemul (trade name, manufactured by Kao Corporation), eleminol [trade name, Sanyo Chemical ( Co., Ltd.), Aqualon (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Adecaria Soap (trade name, manufactured by Asahi Denka Kogyo Co., Ltd.) and the like.

The amount of the radical polymerizable surfactant used depends on the type of the surfactant or the type of the monomer used, but generally, the total amount of the used monomer is 100%.
It is preferably 0.1 to 5 parts by mass with respect to parts by mass. If the amount is less than 0.1 part by mass, the stability of the emulsion obtained during the emulsion polymerization or the obtained emulsion may be reduced. If the amount exceeds 5 parts by mass, the effect of water resistance in proportion to the amount added may be improved. Not only that it is not recognized, but rather the water resistance may be reduced and it is desirable to avoid it.

In production method 1) -1, high-temperature continuous polymerization can be employed. According to the high-temperature continuous polymerization method, a prepolymer having a low viscosity and a low molecular weight can be obtained, and further, the polymerization method does not require the use of a thermal polymerization initiator, or a small amount even when a thermal polymerization initiator is used. Since a prepolymer having a target molecular weight can be obtained by using the copolymer, the copolymer is preferable because it has high purity and hardly contains impurities which generate radical species by heat or light, and stable physical properties can be obtained. As a high temperature continuous polymerization method, Japanese Patent Application Laid-Open No. 57-5
02171, 59-6207, 60-21500
A known method disclosed in No. 7 or the like may be used. For example,
Fill the pressurizable reactor with a solvent, set at a predetermined temperature under pressure, then supply a monomer mixture consisting of monomers and, if necessary, a polymerization solvent to the reactor at a constant supply rate, A method of extracting a reaction solution in an amount corresponding to the supply amount of the monomer mixture may be used.

(2) Production method 1) -2 to 5 As a method for producing a prepolymer in the above production method 1) -2 to 5 method, a compound having a hydroxyl group and an ethylenically unsaturated group (hereinafter referred to as a hydroxyl compound) Unsaturated compounds), compounds having an epoxy group and an ethylenically unsaturated group (hereinafter, referred to as an epoxy-based unsaturated compound), compounds having an isocyanate group and an ethylenically unsaturated group (hereinafter, referred to as an isocyanate-based unsaturated compound), and ethylenic compounds. It can be obtained by polymerizing a compound having an unsaturated group and an acid anhydride group (hereinafter referred to as an acid anhydride-based unsaturated compound).

Examples of the hydroxyl-based unsaturated compound include hydroxyalkyl (meth) acrylates such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate.
Examples include acrylates and hydroxyalkyl vinyl ethers such as hydroxybutyl vinyl ether.

Examples of the epoxy-based unsaturated compound include glycidyl (meth) acrylate and epoxy group-containing (meth) acrylate such as cyclohexene oxide group-containing (meth) acrylate represented by the following formula (3).

[0036]

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As the isocyanate-based unsaturated compound,
Examples thereof include (meth) acryloyloxyethyl isocyanate and dimethyl-m-isopropenylbenzyl isocyanate represented by the following formula (4).

[0038]

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Examples of the acid anhydride unsaturated compound include maleic anhydride and itaconic acid.

The prepolymer can be copolymerized with a monomer copolymerizable with the unsaturated compound, if necessary. can do.

As a method for producing the prepolymer, the prepolymer can be produced by polymerizing the monomers according to a conventional method such as a solution polymerization method, an emulsion polymerization method, and a high-temperature continuous polymerization method. Method can be adopted.

In the above methods 1) -2 to 5, the isocyanate maleimide compound [method 1) -2] and the carboxyl maleimide compound [1) -3 are added to the prepolymer having various functional groups, respectively. Method], and a hydroxyl maleimide compound [Methods 1) -4 and 5 above] are subjected to an addition reaction.

Examples of the isocyanate-based maleimide compound include a compound represented by the following formula (5).

[0044]

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[However, in the formula (5), R ¹ and R ² have the same meaning as described above. R ⁵ represents a linear or branched alkylene group having 1 to 6 carbon atoms. ]

Examples of the carboxyl maleimide compound include compounds represented by the following formula (6).

[0047]

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[However, in the formula (6), R ¹ and R ² have the same meanings as described above. R ⁶ represents a linear or branched alkylene group having 1 to ⁶ carbon atoms. ]

The hydroxyl maleimide compound is represented by the following formula:
And the like.

[0050]

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[However, in the formula (7), R ¹ and R ² have the same meanings as described above. R ⁷ represents a linear or branched alkylene group having 1 to 6 carbon atoms. ]

In any case, it can be produced by adding each compound to the prepolymer in an organic solvent, an aqueous medium or without solvent. As the conditions of each addition reaction, a reaction temperature, a reaction time, and a catalyst may be selected according to each reaction.

2) Maleimide group and ethylenically unsaturated group
As the maleimide polymer in the present invention , a polymer having a maleimide group and an ethylenically unsaturated group (hereinafter referred to as a maleimide unsaturated polymer) is more preferable because of its excellent curability.

There are various ethylenically unsaturated groups in the maleimide unsaturated polymer, and examples thereof include a vinyl group, an allyl group and a (meth) acryloyl group, and a (meth) acryloyl group is preferred.

As the maleimide unsaturated polymer, polymers obtained by various methods can be used. As the production method, there are various methods, the following 2) shown in -1 to 5, to prepare a prepolymer having a functional group and a maleimide group, which has a functional group capable of reacting with the functional group A method of reacting a compound, and a prepolymer having a functional group shown in 2) -6 and 7 below are prepared, and a compound having a maleimide group and a functional group capable of reacting with the functional group are reacted with the prepolymer. The method is preferred.

2) -1 A method of adding an isocyanate-based unsaturated compound to a maleimide group- and hydroxyl group-containing prepolymer. 2) -2 A method of adding an epoxy unsaturated compound to a prepolymer containing a maleimide group and a carboxyl group. 2) -3 maleimide group and epoxy group-containing prepolymer,
A method of adding a compound having an ethylenically unsaturated group and a carboxyl group (hereinafter, referred to as a carboxyl unsaturated compound). 2) A method of adding a hydroxyl-based unsaturated compound to a prepolymer containing a -4 maleimide group and an isocyanate group. 2) -5 maleimide group and acid anhydride group-containing prepolymer,
A method of adding a hydroxyl-based unsaturated compound. 2) A method in which a hydroxyl maleimide compound and a hydroxyl unsaturated compound are added to a -6 acid anhydride group-containing prepolymer. 2) A method of adding a carboxyl maleimide compound and a carboxyl unsaturated compound to a -7 epoxy group-containing prepolymer.

(1) Method for Producing Prepolymer As a method for producing a prepolymer having a maleimide group in the above-mentioned methods 2) to 1 to 5, a maleimide monomer and a hydroxyl-based unsaturated compound [2] ) -1), carboxyl unsaturated compound (2) -2), epoxy unsaturated compound (2) -3), isocyanate unsaturated compound (2) -4 And a compound having an ethylenically unsaturated group and an acid anhydride group (hereinafter referred to as an acid anhydride-based compound) [method 2) -5] to obtain a prepolymer.

Maleimide monomer, hydroxyl-based unsaturated compound,
As the epoxy-based unsaturated compound, the isocyanate-based unsaturated compound and the acid anhydride-based unsaturated compound, the same compounds as described above can be used.

As the carboxyl unsaturated compound,
Oligomers of dimer or more which are the products of Michael addition of unsaturated carboxylic acids such as (meth) acrylic acid, crotonic acid, cinnamic acid, (meth) acrylic acid, ω-carboxypolycaprolactone mono (meth) acrylate, phthalate And carboxyl group-containing (meth) acrylates such as monohydroxyethyl (meth) acrylate and monohydroxyethyl (meth) acrylate succinate.

In the above method 2) -6, a prepolymer can be obtained by polymerizing an acid anhydride unsaturated compound and in the above method 2) -7, an epoxy unsaturated compound. it can.

Other monomers can be copolymerized with the prepolymer, if necessary. As the other monomers, those similar to the above can be exemplified.

The prepolymer can be produced by polymerizing the above-mentioned monomer according to a conventional method such as a solution polymerization method, an emulsion polymerization method or a high-temperature continuous polymerization method. These polymerization methods are the same as described above. Method can be adopted.

(2) Method for Producing Maleimide Unsaturated Polymer In the above methods 2) -1 to 5, the maleimide group-containing prepolymer having various functional groups is added to the isocyanate-based unsaturated compound [2] -1 Method), epoxy unsaturated compound [the method of 2) -2], carboxyl unsaturated compound [the method of 2) -3] and hydroxyl unsaturated compound [the
2) Methods of -4 and 5] can be obtained to obtain a polymer. Further, in the above method 2) -6, a hydroxyl maleimide compound and a hydroxyl unsaturated compound are added to the acid anhydride group-containing prepolymer, and in the method 2) -7, the epoxy group-containing prepolymer is added. A polymer can be obtained by adding a carboxyl maleimide compound and a carboxyl unsaturated compound to the polymer. Examples of the unsaturated compound and the maleimide compound include the same compounds as described above.

In any case, it can be produced by adding each compound to the prepolymer in an organic solvent, an aqueous medium or without solvent. As the conditions of each addition reaction, a reaction temperature, a reaction time, and a catalyst may be selected according to each reaction.

The proportion of the maleimide group in the imide unsaturated polymer is preferably from 10 to 40% by weight of the maleimide group-containing monomer based on all the monomers used. If this ratio is less than 10% by weight, the weather resistance may be insufficient, or curing or crosslinking (hereinafter simply referred to as “curing”) may be insufficient, resulting in insufficient hardness. When a thick film is cured, the cured film proceeds only on the surface, and the adhesion may be poor. The proportion of the ethylenically unsaturated group in the maleimide unsaturated polymer is preferably from 10 to 40% by weight of the monomer having an ethylenically unsaturated group based on all the monomers used. If this proportion is less than 10% by weight, the weather resistance is insufficient or the curing is insufficient, resulting in insufficient hardness.
Adhesion may be poor.

3) Maleimide unsaturated polymerization having an acidic group
When the composition of the present invention is used as an aqueous composition, a polymer having an acidic group (referred to as acidic maleimide unsaturated polymer) or a salt thereof (hereinafter referred to as "acidic maleimide unsaturated polymer") is used as the maleimide unsaturated polymer. (Referred to as “salt”) is preferred because of its better water resistance. Examples of the acidic group include a carboxyl group, a sulfonyl group, and a phosphoric acid group, and a carboxyl group is preferable.

As the acidic maleimide unsaturated polymer in the present invention, acidic polymers obtained by various methods can be used, and those obtained by the following methods 3) to 1-6 are preferable. 3) -1 In the prepolymer having a maleimide group and an acidic group,
A method of adding an epoxy-based unsaturated compound. 3) -2 A method in which an acidic unsaturated compound is added to a prepolymer having a maleimide group and an epoxy group, and an acid anhydride is added to a hydroxyl group generated by this reaction. 3) A method of adding an isocyanate-based unsaturated compound to a prepolymer having a -3 maleimide group, a hydroxyl group and an acidic group. 3) A method of adding a hydroxyl-based unsaturated compound to a prepolymer having a -4 maleimide group, an isocyanate group and an acidic group. 3) A method of adding a hydroxyl-based unsaturated compound to a prepolymer having a -5 maleimide group and an acid anhydride group. 3) A method of adding a compound having a maleimide group and a hydroxyl group and a hydroxyl-based unsaturated compound to a prepolymer having a -6 acid anhydride group.

(1) Method for Producing Prepolymer As a method for producing a prepolymer having a maleimide group in the above-mentioned methods 3) -1 to 5-5, a maleimide-based unsaturated compound and an acidic unsaturated compound [ 3) -1 method), epoxy unsaturated compound (3) -2 method),
Hydroxy unsaturated compounds and acidic unsaturated compounds (3) -3
Method), an isocyanate-based unsaturated compound and an acidic unsaturated compound (the method of the above 3) -4), and an acid anhydride-based unsaturated compound [the method of the above 3) -5). Can be obtained. Examples of these unsaturated compounds include the same as described above.

Other monomers can be copolymerized with the prepolymer as needed. As the other monomers, those similar to the above can be mentioned.

The prepolymer can be produced by polymerizing the starting monomers according to a conventional method such as a solution polymerization method, an emulsion polymerization method or a high-temperature continuous polymerization method. In the production of the prepolymer, the isocyanate-based unsaturated compound and the acid anhydride-based unsaturated compound which are not decomposed by water are not used, and in the above 3) -1 and 2 production methods,
Any of solution polymerization, emulsion polymerization and high-temperature continuous polymerization can be employed, and in the above 3) -3 to 6 using the isocyanate unsaturated compound, the solution polymerization and the high-temperature continuous polymerization are used. It is preferable to employ Examples of the solution polymerization method, the high-temperature continuous polymerization method, and the emulsion polymerization method include the same methods as described above.

In the present invention, in order to further improve the polymerization stability, other emulsifiers can be used in combination with the composition as long as physical properties such as water resistance and chemical resistance are not impaired. As other emulsifiers, the same as those described above can be used.

(2) Method for producing acidic maleimide unsaturated polymer
Method 3) In the method of -1 to 5, the maleimide group-containing prepolymer having various functional groups, respectively, an epoxy unsaturated compound [the method of 3) -1], an acidic unsaturated compound and an acid anhydride [Method of the above 3) -2], an isocyanate-based unsaturated compound [Method of the above 3) -3], an acidic polymer by adding a hydroxyl-based unsaturated compound [Method of the above 3) -4, 5] Can be obtained. In the above method 3) -6, an acidic polymer can be obtained by adding a hydroxyl maleimide compound to the acid anhydride group-containing prepolymer.
Examples of the unsaturated compound and the maleimide compound include the same compounds as described above.

In the production of the prepolymer or the addition reaction of the unsaturated compound, the isocyanate-based unsaturated compound and the acid anhydride-based unsaturated compound which are decomposed by water are not used. In the production method of (2), an acidic polymer can be produced by adding each unsaturated compound to the prepolymer in an organic solvent, an aqueous medium or without a solvent. Also, the above 3) -3 to 6 using an isocyanate-based unsaturated compound and an acid anhydride-based unsaturated compound.
In the production method, it is preferable to add each unsaturated compound to the prepolymer in an organic solvent or without a solvent.
The conditions of each addition reaction include a reaction temperature,
The reaction time and catalyst may be selected.

The weight average molecular weight of the unsaturated acidic maleimide polymer is preferably from 1,000 to 500,000, more preferably from 2,000 to 100,000. If this value is less than 1000, the strength and water resistance of the cured film may be insufficient, while the value may be less than 50.
If it exceeds 000, the viscosity may be too high, and the workability may decrease or the coating property may decrease.

The acid value of the acidic polymer is preferably from 20 to 400, and more preferably from 40 to 200. When the acid value is less than 20, the dispersion stability may decrease, and when the acid value exceeds 400, the water resistance and alkali resistance of the cured film may decrease. When a highly hydrophobic monomer is used as a monomer constituting the copolymer, the acid value is preferably 100 to 400.

In the composition of the present invention, some or all of the acidic groups in the acidic polymer are neutralized with an alkaline compound, and dissolved or dispersed in an aqueous medium as a salt of the acidic polymer. It is preferable to use as. The resulting aqueous composition is excellent in stability. As a method of forming a salt of the acidic polymer, the prepolymer may be used, or the acid polymer may be used.However, in the prepolymer stage, the salt of the acidic polymer is prepared using ammonia or an organic amine described below. Is particularly preferred because it also serves as an addition catalyst in the addition reaction of the epoxy unsaturated compound. A method for converting a prepolymer obtained by solution polymerization or an acidic polymer obtained by adding an unsaturated compound in an organic solvent into a salt may be a conventional method. For example, a method of adding a prepolymer or an acidic polymer to an aqueous medium with stirring, neutralizing the prepolymer or the acidic polymer with an alkaline compound to form a salt of the prepolymer or the acidic polymer, and then adding this to the aqueous medium And a method of adding the mixture under stirring.

A prepolymer obtained by an emulsion polymerization method,
Alternatively, as a method for converting an acidic polymer obtained by adding an unsaturated compound into an aqueous dispersion of a prepolymer into a salt, an alkaline compound is directly added after the polymerization reaction or the addition reaction is completed, and the prepolymer or the acidic polymer is added. It can be a combined salt.

As the alkaline compound, ammonia,
Examples include organic amines and inorganic bases such as sodium hydroxide and potassium hydroxide. Among them, ammonia or a low molecular weight organic amine such as trimethylamine, triethylamine and dimethylethanolamine is preferred because the cured film is evaporated and scattered from the cured film during drying and the finally obtained cured film has excellent water resistance.

The neutralization ratio of the acidic polymer is preferably from 10 to 100 mol%, more preferably from 30 to 100 mol%, based on the total amount of the acidic groups in the polymer.
Mol%. If this ratio is less than 10 mol%, the copolymer may be difficult to dissolve or disperse in the aqueous medium. Similarly, the addition ratio of the alkaline compound is preferably from 10 to 100 mol%, more preferably from 30 to 100 mol%, based on the total amount of the acidic groups in the polymer. If this proportion is less than 10 mol%, the polymer may be difficult to dissolve or disperse in the aqueous medium as described above, while if it exceeds 100 mol%, ammonia or amine may be used as an alkaline compound. When is used, an odor may remain in the obtained aqueous composition.

2) Other Components In addition to the maleimide polymer, other components can be added to the composition as required.

For the purpose of improving the strength, water resistance and chemical resistance of the cured film, it is preferable to add a compound having two or more ethylenically unsaturated groups. As the compound,
Compounds having two or more (meth) acryloyl groups are preferred, and examples include monomers and oligomers.

Examples of the monomer include alkylene glycol di (meth) acrylates such as ethylene glycol di (meth) acrylate and propylene glycol di (meth) acrylate; diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, Low molecular weight polyalkylene glycol di (meth) such as dipropylene glycol di (meth) acrylate and tripropylene glycol di (meth) acrylate
Acrylate or its alkylene oxide modified product; trimethylolpropane tri (meth) acrylate, pentaerythritol di or tri (meth) acrylate or pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate and dipentaerythritol penta or hexa Examples thereof include polyol poly (meth) acrylates such as (meth) acrylates and alkylene oxide modified products thereof; and di- and tri (meth) acrylates of isocyanuric acid alkylene oxide modified products.

Examples of the oligomer include urethane (meth) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate and polyether (meth) acrylate.

The compounding ratio of the compound having two or more ethylenically unsaturated groups is preferably from 0 to 120% by mass based on the maleimide polymer in the composition. If it exceeds 120% by mass, the stability of the composition may decrease.

In order to adjust the adhesiveness and flexibility of the cured film, hydroxyalkyl (meth) acrylate, (meth) acrylate of alkylene oxide adduct of phenol, or the Compounds having one ethylenically unsaturated group, such as halogen nucleus substitutes, glycol mono (meth) acrylates and N-vinyl compounds, can also be blended.

The composition of the present invention is crosslinked by irradiation with active energy rays. Since the polymer used has a maleimide group, it can be easily crosslinked by active energy rays and further crosslinked by ultraviolet rays. No photopolymerization initiator or a small amount of photopolymerization initiator, which has excellent cross-linking, but for the purpose of further improving curability, the photopolymerization initiator in a range that does not impair the weather resistance Can be blended.

Examples of the photopolymerization initiator include benzoin such as benzoin, benzoin methyl ether, benzoin ethyl ether and benzoin isopropyl ether and their alkyl ethers, acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy- 2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxyacetophenone, 1-hydroxycyclohexylphenylketone and 2-methyl-
Acetophenones such as 1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone and 2-amylanthraquinone Anthraquinone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone and 2,2
There are thioxanthone such as 4-diisopropylthioxanthone, ketal such as acetophenone dimethyl ketal and benzyl dimethyl ketal, benzophenone such as benzophenone, and xanthone. These photopolymerization initiators can be used alone or in combination with a benzoic acid-based or amine-based photopolymerization initiator. The preferred mixing ratio of these photopolymerization initiators is 5 parts by mass or less, more preferably 2 parts by mass or less, per 100 parts by mass of the composition.

When the composition to be used is an aqueous composition, the coated surface is heated before irradiation with the active energy ray, and water as a dispersion medium and ammonia or an organic amine as an alkaline compound are used. Preferably, these are evaporated and scattered. As a result, it is possible to prevent a decrease in film strength and transparency when moisture remains in the film, and a decrease in odor and weather resistance when ammonia or organic amine remains in the film.

In addition to the above, as additives, for example, pigments and dyes; fillers such as clay, talc and titanium white; film-forming assistants such as butyl cellosolve, butyl carbitol and dipropylene glycol monobutyl ether; Plasticizers such as phthalate and dioctyl phthalate; tackifiers such as rosin, tempenphenol and petroleum resin; various surfactants used for purposes such as wetting, dispersion and defoaming; thickeners; thixoagents; Etc. can be blended. The composition contains at least 2 per molecule
A compound having two or more hydrazine groups or semicarbazide groups can be used in combination. In this case, a polymer having a carbonyl group is employed as the polymer.

3) Method for Producing the Composition As a method for producing the composition, an organic solvent solution or an emulsion containing the maleimide polymer obtained by the method for producing the maleimide polymer may be used, or may contain the maleimide polymer. A method of stirring and mixing an organic solvent solution or an emulsion with other components is exemplified. The proportion of the polymer in the composition of the present invention is 5% in the case of an organic solvent solution.
To 95% by weight, and in the case of an aqueous dispersion,
It is preferably 70% by weight, more preferably 20 to 60% by weight.

[0091] 2. Coating method The coating method of the present invention is a method in which a curable composition is applied to a substrate, irradiated with active energy rays, and then cured by sunlight. The coating method of the present invention can be preferably applied to coating of an aqueous composition. As the substrate, for example, glass,
Examples include metals, wood, plastics, and inorganic materials such as slate and concrete. The coating method of the present invention can be preferably applied to factory line coating, and the base material is preferably an inorganic molded material. Examples of the inorganic molding material include a sizing board, a roof tile, an ALC board, a PC board, and a slate board. As the inorganic molding material, a material using cement as a binder is preferable. The coating method may be a conventional method, for example, a roll coater,
Examples include flow coater, spray, dipping and brush coating. When the composition is an organic solvent solution or an emulsion of a polymer, it is dried after coating. The coating amount may be appropriately set according to the purpose of use, and the preferable coating amount is 10 to 300 g / cm ² , more preferably 20 to 100 g / cm ² . Examples of the active energy ray include an ultraviolet ray and an electron beam, and an ultraviolet ray is preferable because an inexpensive apparatus can be used. Various light sources can be used as a light source for curing with ultraviolet rays, and examples thereof include a high-pressure mercury lamp, a metal halide lamp, a xenon lamp, an electrodeless discharge lamp, and a carbon arc lamp. The coating film cured by the active energy rays is cured by sunlight. As a specific method, usually, it is only necessary to install it as a sizing material at a construction site and leave it outdoors. INDUSTRIAL APPLICABILITY The present invention is suitably used for surface coating on an inorganic molding material, particularly in the production of a sizing material.

[0092]

The present invention will now be described more specifically with reference to examples and comparative examples. In each example, "parts" means parts by mass, and "%" means mass%.

Production Example 1 A flask equipped with a stirrer, a thermometer and a cooler was charged with 140 parts of ion-exchanged water, set in a water bath, and the internal temperature was adjusted to 80 ° C. while blowing nitrogen. Next, 1 part of ammonium persulfate as a polymerization initiator was dissolved in 3 parts of ion-exchanged water and added. Five minutes after the addition, a maleimide monomer having the composition shown in Table 1 and represented by the following formula (8) (hereinafter referred to as THPI)
Acrylate), ethyl acrylate (hereinafter, referred to as EA), methyl methacrylate (hereinafter, referred to as MMA), cyclohexyl methacrylate (hereinafter, referred to as CHMA) and methacrylic acid (hereinafter, referred to as MAA), and octyl thioglycolate (hereinafter, referred to as MAA) as a chain transfer agent. OTGA
) Was dropped at 80 ° C over 2 hours, and maintained at 80 ° C for 1 hour after the completion of the dropping. Thereafter, 0.1 part of t-butyl hydroperoxide was diluted with 2 parts of ion-exchanged water and added. Five minutes later, 0.3 parts of sodium hydrosulfite was added to 5 parts of ion-exchanged water.
Then, the mixture was charged into the mixture, and the internal temperature was maintained at 80 ° C. for 1 hour.
As a result, a polymer emulsion having an NV of about 40 was obtained. This is called A-1.

[0094]

Embedded image

Production Example 2 A monomer was polymerized in the same manner as in Production Example 1, except that 100 parts of a mixed solution comprising a monomer having the composition shown in Table 1 and a chain transfer agent was used. The obtained reaction solution is added to ion-exchanged water 20
, 5 parts of tetraethylamine (hereinafter referred to as TEA) and 0.05 parts of hydroquinone monomethyl ether were added to the reaction solution and stirred for 1 hour to neutralize the polymer. still,
TEA also acts as a catalyst for the subsequent addition reaction. After confirming that no aggregate was formed in the reactor and that the internal temperature was stabilized at 80 ° C., 16.5 parts of glycidyl methacrylate (hereinafter referred to as GMA) was further charged. A time addition reaction was performed. As a result, a liquid in which a polymer having an NV of about 40 was dissolved or dispersed in water (hereinafter, referred to as an aqueous liquid) was obtained. This is called A-2.

[0096]

[Table 1]

Production Example 3 The monomers shown in Table 2 were mixed, mixed with 100 parts of deionized water and 1 part of a reactive emulsifier (Aqualon HS10), and the monomer emulsion was mixed using a rotary homomixer. Manufactured. A flask containing 52 parts of deionized water, 1 part of APS, and 1 part of an emulsifier (active ingredient) was purged with nitrogen and heated to 80 ° C., and the monomer emulsion was added dropwise over 2 hours, and then aged for 2 hours. . To the obtained reaction solution, 2 parts of an aqueous ammonia solution (10%) was added to adjust the pH. As a result, a polymer emulsion having an NV of about 40 was obtained. This is A-
Three.

Comparative Production Example 1 A polymer emulsion was produced in the same manner as in Production Example 3 except that the components shown in Table 2 were used. As a result, NV about 4
0 polymer emulsion was obtained. This is called B-1.

[0099]

[Table 2]

Production of curable aqueous coating composition According to a conventional method, the components shown in Table 3 were stirred and mixed to produce a curable aqueous coating composition.

[0101]

[Table 3]

Comparative Examples 1 to 16 The composition obtained was applied to a substrate with a 100 μm bar coater, dried at 80 ° C. for 3 minutes, and 1000 mJ / cm ² (condition 1) using a mercury lamp or 200 mJ / cm ²
The ultraviolet light of (condition 2) was irradiated. The amount of ultraviolet light is 3
It was measured using an integrating light meter (Oak Seisakusho) having sensitivity to light having a wavelength of 65 nm. For hardness and blocking resistance, an aluminum plate was used. For freeze-thaw property, 100 g of a solvent-based acrylic urethane white paint was used.
/ M ² A slate plate coated was used. The obtained cured film was evaluated according to the following. Table 4 shows the results.

○ Evaluation Hardness The pencil hardness was measured according to JIS5400.

Blocking Resistance The coated surfaces of the two test pieces were put together, a load of 10 kg was maintained at 30 ° C. for 24 hours, then the two test pieces were peeled off, and the results were visually observed according to the following criteria. evaluated. ；: Peeled off without any problem, △: State where adhesion trace remains, ×;
Destruction of coating or substrate

Freezing / thawing Freezing (−20 ° C. × 2 hours) / thawing (immersing in water at 20 ° C.)
The state of the coating film after 20 cycles of (1 hour) was observed. ；: No problem, Δ: slight cracking, ×: cracking in the whole

[0106]

[Table 4]

Examples 1 to 14, Comparative Examples 17 and 18 The cured films obtained in Comparative Examples 1 to 16 were exposed to the roof southern surface for 7 days (45 ° surface). The same evaluation as in the above comparative example was performed on the cured film after being cured by sunlight. Table 5 shows the results.

[0108]

[Table 5]

[0109]

According to the coating method of the present invention, the cured film obtained has excellent blocking resistance and freeze-thaw property, and is particularly applicable to the production of sizing materials.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B05D 5/06 104 B05D 5/06 104G 7/00 7/00 DE L 7/24 301 7/24 301T 302 302X 303 303E C09D 4/00 C09D 4/00 5/00 5/00 Z 201/02 201/02 F term (reference) 4D075 AA01 AB01 AC21 BB42Y BB46Y BB47Y CA08 DA06 DB01 DB11 DC02 EB39 EC37 4J038 CC091 CC092 CE051 CE052 CG02 CG022 CG031 CG032 CG071 CG072 CG081 CG082 CG141 CG142 CH001 CH002 CH051 CH052 CH061 CH062 CH121 CH122 CH131 CH132 CH171 CH172 CH201 CH202 CH221 CH222 CJ031 CJ032 CJ041 CJ042 CJ101 CJ102 CJ131 C1021 GA06 GA07 GA08 GA11 GA13 GA14 HA156 JB01 JB03 JB09 KA09 KA16 LA02 MA08 NA03 NA10 NA14 PA 17 PB05 PC02 PC03 PC04 PC06 PC08

Claims (5)

[Claims] 1. A coating method comprising applying a curable composition containing a polymer having a maleimide group to a substrate, irradiating the substrate with an active energy ray, and curing the composition with sunlight. 2. The coating method according to claim 1, wherein said composition further contains a compound having two or more ethylenically unsaturated groups. 3. The polymer according to claim 1, wherein the polymer has a maleimide group and an ethylenically unsaturated group.
The painting method described. 4. The composition according to claim 1, wherein said composition is an aqueous composition.
The coating method according to claim 3. 5. The method according to claim 1, wherein said base material is an inorganic molding material.
The coating method according to claim 4.