JP3053286B2 - Thermosetting coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thermosetting coating composition. More specifically, the present invention relates to a thermosetting coating composition which enables formation of a coating with less warpage.

[0002]

2. Description of the Related Art In general, methacrylic resins containing methyl methacrylate as a main component are used for lighting covers, automobile parts, and the like due to their excellent weather resistance, transparency and excellent appearance.
Signboards, decorative articles, used in various fields such as miscellaneous goods, and because it can be expected to have a good appearance such as its excellent surface properties, it is also possible to coat a methacrylic resin on the surface of various kinds of different resins. It is performed in various fields. Conventionally, various methods for performing these coating treatments have been proposed. For example, (a) a syrup comprising a methyl methacrylate monomer and a linear polymer thereof is impregnated, and then heated and compressed to obtain a coated molded article. Method of obtaining
JP-A-94804), (b) a method of laminating a sheet-form methacrylic resin on a decorative sheet under heat and pressure to obtain a coated molded product (JP-A-47-11396), and (c).
A method in which a film-formed methacrylic resin is brought into contact with the surface of a semipolymer containing a polymerizable monomer and a solvent, and the uncured material is cured by heating to obtain a coated product (Japanese Patent Laid-Open No. 57-135122).
Publication) and (d) a method of applying an acrylic paint to a substrate.

[0003]

However, although the method of impregnating syrup (a) is excellent in adhesiveness, it has a problem that it is difficult to increase the thickness of the coating layer and requires many steps. On the other hand, the method using (b) sheet-like or (c) film-like methacrylic resin requires pre-processing into various sheets or films depending on the thickness of the coating layer, matte appearance, etc. There was a problem that is. In the method (d), it is difficult to increase the thickness of the coating layer. To secure a predetermined coating film thickness, it is necessary to apply several coating layers. In addition, the adhesion of each layer is improved or the coating film is smoothed. In order to improve the properties, it is necessary to sand before applying the next layer, or the surface of the final finishing layer may be polished, resulting in a complicated process. Further, when the linear expansion coefficient of the coating layer is significantly different from that of the substrate, there is a problem that the coated product is likely to be warped, and this is particularly a problem when the coating layer is thick.

[0004] Accordingly, an object of the present invention is to provide a thermosetting coating composition which has the same permeability and fluidity as syrup and is easy to handle, in order to solve the above problems.
It is still another object of the present invention to provide a coating composition which not only facilitates the adjustment of the thickness of the coating layer and facilitates the formation of a thick coating layer, but also enables the formation of a coated product with less warpage.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies on various materials for the problems to be solved, and as a result, have disclosed JP-A-60-202128 and JP-A-62-1.
No. 705, JP-A-2-294311, etc., a partially crosslinked gel polymer which is a methacrylic resin molding material, and a composition obtained by imparting flexibility to a composition having improved fluidity for coating. The present invention was found to be extremely useful as a composition, and the present invention was completed.

That is, an object of the present invention is to provide (A) 3 to 60% by weight of a crosslinkable monomer mainly composed of di (meth) acrylate containing at least two urethane bonds, and (B) methyl methacrylate. By heating in the presence of a polymerization initiator a mixture consisting of 97 to 40% by weight of an unsaturated monomer which is mainly composed of
And the total amount of monomers present in the mixture reacts.
Stop the reaction when a part of it has reacted without performing
Consisting of a partially crosslinked gel-like polymer obtained by
In the thermosetting coating composition, the gel-like partially crosslinked
The polymer content (% by weight) in the coalesce should not exceed 80% by weight.
And the polymer content in the mixture (weight
Thermosetting coating composition characterized and 4-62% by weight than the amount%) higher this, the gel partially crosslinked polymer (hereinafter
Hereinafter, the "gel-like partially crosslinked polymer " is referred to as " partially crosslinked gelled polymer ") , and the coating composition obtained by crushing the particles to an average particle size of 5 mm or less, and the partially crosslinked gelled polymer or crushed thereof 100 parts by weight of a partially crosslinked gel polymer obtained and a composition comprising 1 to 100 parts by weight of a syrup dissolved and containing an unsaturated monomer mainly composed of methyl methacrylate or a polymer thereof. This can be achieved by a coating composition.

Hereinafter, the present invention will be described in more detail.

[0008] The technical idea of the present invention is that a crosslinkable monomer mainly composed of di (meth) acrylate containing at least two urethane bonds having an effect of improving adhesion to metals and wood materials, and methyl methacrylate are used. With an appropriate combination of an unsaturated monomer which may be a main component and may contain and dissolve the polymer, the coating composition of the present invention is cured, and the finally obtained coating layer has appropriate flexibility. By giving strength,
Even if the linear expansion coefficient of the coating layer and the base material covered by the coating layer are different, it is possible to reduce the occurrence of warpage during molding of the coated product and to easily form a thick coating layer which is easy to handle. It is an object of the present invention to provide a coating composition comprising a partially crosslinked gel polymer.

The crosslinkable monomer (A) mainly composed of di (meth) acrylate containing at least two urethane bonds used in the present invention is defined by the following formulas (1) to (1).
Compounds represented by (4) alone or Formulas (1) to (4)
And a mixture with another crosslinkable monomer copolymerizable therewith, and various crosslinkable monomers can be used in combination.

The di (meth) acrylate containing at least two urethane bonds according to the present invention is a compound represented by the following formulas (1) to (4).

(M) A—O—R ₁ —OCONH—R ₂ —NHCOO—R ₁ —O— (M) A (1)

[Wherein (M) A represents a methacryloyl group or an acryloyl group, R ₁ represents a substituted or unsubstituted alkylene group having 2 to 10 carbon atoms, and R ₂ represents a carbon atom excluding the carbon number of the isocyanate group. The number represents 2 to 15 diisocyanate residues. ]

(M) A—O—R ₃ —NHCOO—X—CONH—R ₃ —O— (M) A (2)

[Wherein (M) A represents a methacryloyl group or an acryloyl group, R ₃ represents an ethylene group, a propylene group, a methylethylene group, or a tetramethylene group;
X is represented by R ₄ —Y—R ₄ —O— (where R ₄ represents an ethylene group or a propylene group, and Y represents an optionally hydrogenated polybutadiene or polyisoprene having a molecular weight of 300 to 4000). group, a polyether polyol residues having a molecular weight of 300 to 3000 to -R ₃ -O- repeating units, poly (.epsilon.-caprolactone) diol residues with a molecular weight of _{300~3000, - (R 5 -OCOR 6} CO
O) _n -R ₅ -O- (wherein R ₅ represents a polyol residue having 2 to 10 carbon atoms, the molecular weight R ₆ is represented by representing the dicarboxylic acid residue having 2 to 15 carbon atoms) 300-3000
Represents a polyester polyol residue. ]

[0015]

Embedded image

[0016]

Embedded image

In the formulas (3) and (4), (M) A represents a methacryloyl group or an acryloyl group, R ₁ represents a substituted or unsubstituted alkylene group having 2 to 10 carbon atoms, and R ₂ represents the number of carbon atoms, excluding the carbon number of the isocyanate groups represents a diisocyanate residue of 2 to 15, X is R ₄ -
Y—R ₄ —O— (where R ₄ represents an ethylene group or a propylene group, and Y represents an optionally hydrogenated molecular weight of 300
A polybutadiene or polyisoprene having a molecular weight of from 300 to 300 having a repeating unit of —R ₃ —O—,
Poly (ε-caprolactone) having a molecular weight of 300 to 3000
Diol _{residues, - (R 5 -OCOR 6 COO} ) n -R 5 -O
Wherein R ₅ represents a polyol residue having 2 to 10 carbon atoms and R ₆ represents a dicarboxylic acid residue having 2 to 15 carbon atoms, wherein the polyester polyol residue has a molecular weight of 300 to 3000. ]

The R ₁ group of the present invention includes, for example, ethylene group, propylene group, methylethylene group, tetramethylene group, hexamethylene group, 2,2-dimethylpropylene group, phenoxymethylethylene group, —CH ₂ CH ₂ OC
_{H 2 CH 2 -, - (} CH 2 CH 2 O) 2 -CH 2 CH 2 -,

[0019]

Embedded image

And the like.

The R ₂ group represents a residue obtained by removing an isocyanate group from diisocyanate. Examples of such a diisocyanate include 1,6-hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene. Diisocyanate, 1,4-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-
Examples include tolylene diisocyanate, p-phenylene diisocyanate, xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, and isophorone diisocyanate.

The R ₅ group represents a residue obtained by removing two hydroxyl groups from a polyol.
For example, ethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol and the like can be exemplified.

The R ₆ group represents a residue obtained by removing two carboxyl groups from a dicarboxylic acid. Examples of such a dicarboxylic acid include adipic acid, phthalic acid, succinic acid, and the like.
Azelaic acid, sebacic acid and the like can be exemplified.

Various compounds represented by the above formulas (1) to (4) can be used.
The compounds of (3) and (4) are preferable, and specific examples thereof include compounds represented by the following formulas (5) to (7) and compounds obtained by hydrogenating the polybutadiene moiety of the formula (7). .

[0025]

Embedded image

[0026]

Embedded image

[0027]

Embedded image

In the formulas (5) to (7), (M) A represents a methacryloyl group or an acryloyl group, R ₇ represents a hydrogen atom, a methyl group or a phenoxymethyl group, and R ₈ represents a hydrogen atom or a methyl group. A represents an integer of 4 to 8,
b represents an integer of 2 to 3, and d represents an integer of 10 to 60. ]

The other crosslinkable monomers copolymerizable with the compounds represented by the formulas (1) to (4) are not particularly limited, but have at least two (meth) acryloyl groups,
Preferably, the monomer is a crosslinkable monomer having 10 or less carbon atoms between the (meth) acryloyl groups, for example, ethylene glycol di (meth) acrylate, 1,4-butylene glycol di (meth) acrylate, 3-butylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, dimethylolethanedi (meth) acrylate, 1,1-dimethylolpropane di (meth) acrylate, 2,2-dimethylol Propane di (meth) acrylate, tetramethylolmethane di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol dimethacrylate, 1,4-bis [(meth) acryloyloxymethyl] Cyclohexane, diethylene glycol di (meth) ac Rate, tetraethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, trimethylolethane tri (meth)
Examples thereof include acrylate, trimethylolpropane tri (meth) acrylate, tetramethylol methane tri (meth) acrylate, and a (meth) acryloyloxy compound having an isocyanuric acid skeleton.

The amount of the crosslinkable monomer (A) used is 3
-60% by weight, preferably 5-55% by weight. If the amount is less than 3% by weight, the gelation time is too slow and the tackiness tends to be too high to make handling difficult. On the other hand, if it exceeds 60% by weight, the flowability of the coating composition deteriorates. There is a tendency and it is not preferable.

In the present invention, the unsaturated monomer (B) which is mainly composed of methyl methacrylate and may contain the polymer is defined as methyl methacrylate alone or methyl methacrylate as a main component and copolymerizable therewith. Α of
The syrup is a mixture with a β-ethylenically unsaturated monomer, or a syrup containing these polymers dissolved in the monomer or monomer mixture.

Examples of the unsaturated monomer which can be copolymerized include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, lauryl acrylate and dicycloacrylate. Alkyl acrylates such as pentenyl acrylate, alkoxyalkyl acrylates such as methoxyethyl acrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, sec-butyl methacrylate,
Alkoxyalkyl such as tert-butyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate, dicyclopentenyl methacrylate, alkyl methacrylate such as 2-ethylhexyl methacrylate, methoxydiethylene glycol methacrylate, methoxytriethylene glycol methacrylate, methoxynonaethylene glycol methacrylate, and n-butoxyethyl methacrylate. Phosphate-containing (meth) acrylates such as methacrylate, mono [2- (meth) acryloyloxyethyl] acid phosphate, hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate and 3-hydroxybutyl acrylate, 2-hydroxy Ethyl methacrylate, Hydroxyalkyl methacrylates such as -hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 2-hydroxy-3-chloropropyl methacrylate, acrylic acid, methacrylic acid, neodymium acrylate, acrylates such as lead acrylate, neodymium methacrylate, methacrylic acid Examples include methacrylates such as lead acid, vinyl chloride, vinyl acetate, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, styrene, α-methylstyrene, vinyltoluene, and maleic anhydride. The phosphate-containing mono (meth) acrylate or di (meth) acrylate as described above has a function of improving the adhesion to metal and is useful.

A syrup containing methyl methacrylate or a polymer of a monomer mixture containing methyl methacrylate as a main component generally refers to a syrup at 25 ° C. of 1 to 30,
It is a monomer solution having a viscosity of 000 centipoise and containing 3 to 40% by weight, preferably 5 to 30% by weight of a polymer.

The elongation at break of a coating layer forming resin obtained by curing the coating composition having the above composition (JIS K63)
01) is not uniform depending on the type and thickness of the substrate to be coated, but is preferably at least 5%, particularly preferably at least 8%, further preferably at least 10%.

The thermosetting coating composition according to the present invention is mainly composed of the above-mentioned crosslinkable monomer (A) and methyl methacrylate, and may contain an unsaturated monomer (B) which may contain the polymer dissolved therein. And a mixture obtained by heating the mixture in the presence of a polymerization initiator to polymerize the mixture, and stopping the reaction at a stage where a part of the monomer present in the mixture has reacted without reacting. It is made of a partially crosslinked polymer in the form of

In this case, the content of the polymer present in the partially crosslinked gel polymer is determined from the polymer content in the mixture of the crosslinkable monomer (A) and the unsaturated monomer (B). Also 4
-62% by weight, preferably 10-62% by weight, most preferably 15-62% by weight, and the total polymer content is in the range not exceeding 80% by weight, preferably not exceeding 62% by weight. When the value of the polymer content is less than 4% by weight, the product does not show a gel state, and handling is inconvenient. On the other hand, when the value is increased by 62% by weight or more or exceeds the upper limit of 80% by weight, There is a tendency that good flow is not shown during molding, which is not preferable.

When the partially crosslinked gel polymer is prepared in the present invention, an ordinary polymerization initiator is used, and one or a mixture of two or more selected from ordinary low-temperature and high-temperature active polymerization initiators is used. Can be used. In general, a low-temperature active polymerization initiator is suitable for the preparation of the partially crosslinked gel polymer, and the decomposition temperature for obtaining a 10-hour half-life is 5 ° C.
0 ° C or less, preferably 26 to 45 ° C, particularly 26 to 41 ° C
And radical polymerization initiators of azo compounds are preferably used. The amount used is 0.001 to 1% by weight, preferably 0.0015 to 0.1% by weight based on the total amount of the crosslinkable monomer (A) and the unsaturated monomer (B).
1% by weight.

In the present invention, the high temperature active polymerization initiator is particularly suitable for polymerization under coating treatment conditions, and has a decomposition temperature of 60 to
A polymerization initiator of 220 ° C. is preferable, and a polymerization initiator having a decomposition temperature of 60 to 170 ° C. is more preferable for improving a processing cycle and storage stability. The amount used is 0.01 to 5% by weight, preferably 0.02 to 4% by weight, based on the total amount of the crosslinkable monomer (A) and the unsaturated monomer (B).
It is.

In the present invention, the partially crosslinked gel polymer is
A mixture of the crosslinkable monomer (A) and the unsaturated monomer (B) is heated and polymerized in the presence of a polymerization initiator. This polymerization reaction is carried out at a temperature of 10 to 95C, preferably 35 to 80C for 10 to 360 minutes. Here, when both the low-temperature active and high-temperature active polymerization initiators are used in combination, almost all of the low-temperature active polymerization initiator is consumed, but the high-temperature active polymerization initiator is not largely decomposed at the reaction temperature and is kept as it is. It remains and acts as a polymerization initiator under subsequent coating processing conditions.

These high-temperature active polymerization initiators may be added together with the low-temperature active polymerization initiator at the time of preparing the partially crosslinked gel polymer, or crushed and kneaded with a kneader or an extruder after the preparation of the partially crosslinked gel polymer. The partially-crosslinked gel polymer may be added and mixed, and the high temperature active polymerization initiator is added to the unsaturated monomer or syrup to be added for the purpose of modifying the fluidity, tackiness, permeability, etc. of the partially crosslinked gel polymer. The rear partially crosslinked gel polymer may be crushed and mixed and kneaded substantially uniformly.

The partially crosslinked gel polymer having a desired polymerization rate can be obtained by stopping the polymerization reaction by quenching or the like, and further comprises the crosslinkable monomer (A) and the unsaturated monomer (B). Can be easily obtained by adding the following regulator to heat-polymerize the mixture with the above in the presence of the polymerization initiator. Such regulators are 1,
4 (8) -P-menthadiene, 2,6-dimethyl-2,
4,6-octatriene, 1,4-P-menthadiene,
1,4-cyclohexadiene and α-methylstyrene dimer.

Such a regulator is used in an amount of 0.0 to the total amount of the crosslinking monomer (A) and the unsaturated monomer (B).
001 to 0.5% by weight, preferably 0.001 to 0.2
%, Most preferably in the range of 0.005 to 0.1%.

The raw material mixture before polymerization of the partially crosslinked gel polymer of the present invention may contain, if necessary, a chain transfer agent, a coloring agent, an organic / inorganic filler, a release agent, an ultraviolet absorber, and a light stabilizer. An additive such as an agent can be blended.

The feature of the present invention resides in that the partially cross-linked gel polymer obtained as described above is used as a thermosetting coating composition.
Since the partially cross-linked gel polymer has shape retention,
It can be handled in any shape such as sheets, rods, blocks, pellets, etc., and flows by applying shear stress at room temperature or at an elevated temperature. Further, it can be crushed for the purpose of improving fluidity. By crushing to an average particle size of 5 mm or less, preferably 2 mm or less, extremely stable fluidity can be obtained, and when the total polymer content is relatively low, for example, not exceeding 50% by weight. Can be easily crushed by using a kneader such as a screw or a calendar roll, or when the total polymer content is relatively high, using a pulverizer such as a ball mill or a cutter mill.

Further, the thermosetting coating composition of the present invention comprises:
100 parts by weight of the partially crosslinked gel polymer or its crushed partially crosslinked gel polymer, and syrups 1 to 100 containing an unsaturated monomer mainly composed of methyl methacrylate or a polymer thereof dissolved therein Parts by weight, preferably 10
６０60 parts by weight can be added and kneaded substantially uniformly, whereby the following favorable effects can be provided. (I) Fluidity is further improved and processing can be performed at a low pressure. (Ii) Adhesion can be adjusted. (Iii) When the total polymer content is relatively high, the permeability to the base material can be improved, and the adhesiveness of the coating layer can be improved. (Iv) In the case of coloring the coating layer, the dye and pigment can be mixed with the unsaturated monomer or syrup to be uniformly colored, and a flowing pattern and a nonuniform spot pattern do not occur. Here, if the amount of the syrup exceeds 100 parts by weight, the shape retention of the composition is not maintained, which is not preferable.

The syrup which may contain the above-mentioned unsaturated monomer mainly composed of methyl methacrylate or its polymer in a dissolved state is the above-mentioned methyl methacrylate or an unsaturated monomer mixture mainly composed of methyl methacrylate, or A syrup containing these polymers in the monomer or monomer mixture, preferably having a viscosity of 4 to 50 poise at 25 ° C., more preferably 6 to 20 poise. Things. These unsaturated monomers or syrups may contain 50% by weight or less of a crosslinkable monomer, if necessary. In this case, the unsaturated monomer or syrup is the same crosslinkable monomer as the partially crosslinked gel polymer. Of course,
Other crosslinkable monomers may be used.

As a method of adding the unsaturated monomer or syrup and kneading substantially uniformly, if the partially crosslinked gel polymer is not crushed, the kneading machine or the crusher is used. On the other hand, when crushed, it can be carried out using a mixing stirrer such as a super mixer or a Hensyl mixer. Here, "substantially uniformly kneaded" means that the syrup kneaded in the coating composition is kneaded to such an extent that the syrup kneaded in the coating composition does not separate and flow out after being left at room temperature for a short time. This state can be achieved by stirring and mixing with a stirrer for several minutes to about 15 minutes.

In the process of crushing the partially crosslinked gel polymer and / or in the process of adding the unsaturated monomer or syrup to the partially crosslinked gel polymer or the crushed polymer and kneading them, It is also possible to add additives such as a mold agent, a colorant, an organic / inorganic filler, an ultraviolet absorber, a light stabilizer, and the like.

The above-mentioned thermosetting coating composition according to the present invention is prepared by placing the composition on a substrate by compression molding, extrusion molding or the like at a temperature of 90 to 180 ° C, preferably 90 to 150 ° C, and 1 to 40 ° C. Heat treatment for 2 minutes, preferably 2 to 20 minutes, to obtain a coated article having a desired coating layer thickness.

The coating composition of the present invention can form a coating layer on various substrates, and examples thereof include synthetic resins, metals, wood agents, and paper. Since it contains, it is suitable for metals, wood materials and the like.
Further, since the coating layer resin formed by curing the composition of the present invention has appropriate flexibility and strength, even if a metal having a coefficient of linear expansion that is significantly different from that of the resin, a base material such as a wood material is used. In addition, it is possible to obtain a coated product having no crack in the coating layer during molding and having less warpage.

If the coefficient of linear expansion of the coating resin is different from the coefficient of linear expansion of the substrate, a difference occurs in the amount of shrinkage between the coating layer and the substrate during the cooling process after the coating composition is disposed on the substrate and heated. For example, the coated product is easily warped. At this time, if the strength of the coating layer is insufficient, the coating layer may be cracked. On the other hand, if the strength of the coating layer is higher than that of the base material, the base material may be cracked.
These tendencies become more remarkable when the thickness of the coating layer is large. When the fluidity of the coating composition is poor, the residual stress of the coating layer tends to increase, in which case the above phenomenon tends to be more remarkable. However, the coating composition of the present invention has good flowability, and the coating layer made of the composition has appropriate flexibility and strength. A coating having a layer can be obtained.

Such a coated article has a coating layer of a crosslinked methacrylic resin and a thick coating layer having a coating thickness of 0.1 to 5 mm, preferably 0.3 to 3 mm. It has good appearance and surface properties, and can be easily molded with little warpage.

[0053]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. The evaluation in Examples and the like was performed by the following method.

(A) Polymer content measurement of partially crosslinked gel polymer; 150 ml of dichloromethane in which 1000 ppm of hydroquinone monomethyl ether was added and dissolved was placed in a Soxhlet extractor, and 15 g of the gel polymer was placed in a cylindrical mouthpiece for extraction. After reflux extraction in a constant temperature water bath kept at 50 ° C. for 20 hours, the extract was put into 1200 ml of methanol to separate the polymer component, and the extract was combined with the polymer component in the slip paper at 55 ° C. Dry under reduced pressure until constant weight with
The weight W (g) of the polymer was determined and calculated by the following equation. Polymer content (%) = (W / weight of gel polymer) × 1
00

(B) Measurement of warpage of coated article;
The coating composition of the present invention is placed on the surface of a SUS plate having a width of 150 mm and a thickness of 0.3 mm, and a coating layer is formed by applying heat and pressure by a method to be described later. The amount of warpage was measured.

(C) Measurement of fracture elongation: The partially crosslinked gel polymer was crushed by an extruder having a screw diameter of 50 mm and L / D = 8 to a maximum particle diameter of 2 mm or less. When the crushed composition does not contain the high temperature active polymerization initiator, 1 part by weight of methyl methacrylate monomer and 2,2-bis (t) are used as the high temperature active polymerization initiator based on 100 parts by weight of the composition.
-Butylperoxy) butane 0.1 part by weight, di-t-butyl peroxide 0.3 part by weight, di-t-butylperoxyhexahydroterephthalate 0.05 part by weight and kneaded with a Hensyl mixer. did. If the crushed composition already contains a high temperature active polymerization initiator, the above operation is unnecessary. 100 kg of the composition obtained in this way is hot-pressed at a mold temperature of 125 ° C. for 20 minutes.
/ Cm ² to form a flat plate with a thickness of about 1 mm
The breaking elongation was measured according to the method of JIS K6301.
The fracture elongation measured as described above is referred to as "fracture elongation of the partially crosslinked gel polymer cured product".

Example 1 (1) Preparation of coating composition: 50 parts by weight of methyl methacrylate monomer, 50 parts by weight of a compound represented by the following formula (8) (TE2000 manufactured by Nippon Soda Co., Ltd.): 1,4 (8 )
0.005 parts by weight of -P-menthadiene and 0.015 parts by weight of 2,2 e-azobis (4-methoxy-2,4-dimethylvaleronitrile) were mixed and dissolved to give a polymer content of 0%.
A mixture by weight was obtained. The mixture was injected into a cell assembled using two glass plates and a gasket so as to have a gasket interval of 10 mm, and polymerized at 60 ° C. for about 2 hours to obtain a partially crosslinked gel polymer. The polymer content of this partially crosslinked gel polymer was 50.7%. When this polymer was extruded with an extruder having a screw diameter of 50 mm and L / D = 8, a composition crushed to a maximum particle size of 2 mm or less was obtained. Subsequently, 100 parts by weight of the crushed composition, 1 part by weight of methyl methacrylate monomer, 0.1 part by weight of 2,2-bis (t-butylperoxy) butane as a high-temperature active polymerization initiator, and di-t-butylperoxide 0.3 parts by weight of oxide and 0.05 parts by weight of di-t-butylperoxyhexahydroterephthalate were kneaded with a Hensyl mixer to obtain a thermosetting coating composition. The “elongation at break of the cured product of the partially crosslinked gel polymer” was 41%.

[0058]

Embedded image

(2) Molding of a coated product: 50 g of the composition obtained in the above (1) was applied to a SUS plate having a length of 250 mm, a width of 150 mm and a thickness of 0.3 mm used as a base material so as to be substantially uniform over the entire surface. The sheet was placed and sandwiched between two polyethylene terephthalate sheets for release having a length of 350 mm, a width of 250 mm, and a thickness of 0.5 mm. These were inserted between hot plates of a press machine previously heated to 125 ° C., heated under pressure of 10 kg / cm ^{2 for} 20 minutes, taken out of the press machine and cooled at room temperature. When the molded product was taken out from between the polyethylene terephthalate sheets, the coating thickness of the obtained coating product was about 0.9 mm, and the adhesion of the coating layer and the appearance were good. The occurrence of warpage was 5 mm.

Example 2 (1) Preparation of a coating composition; each of an unsaturated monomer and a crosslinkable monomer was 50 parts by weight of a methyl methacrylate monomer, and methoxydiethylene glycol methacrylate 40 was used.
2, 2 parts by weight of a compound represented by the following formula (9) (AH-600 manufactured by Kyoeisha Yushi Kagaku Kogyo KK)
Example 1 was repeated except that the amount of e-azobis (4-methoxy-2,4-dimethylvaleronitrile) was 0.018 parts by weight and polymerization was carried out at 60 ° C. for 4 hours and at 90 ° C. for 1 hour. Similarly, a partially cross-linked gel polymer in which the polymer content was increased from 0% by weight to 51.3% by weight was obtained. This polymer was crushed in the same manner as in Example 1, and then compounded and kneaded in the same manner as in Example 1 to obtain a thermosetting coating composition. "Elongation at break of cured product of partially crosslinked gel polymer" is 10
%Met.

[0061]

Embedded image

(2) Molding of coated article: The composition of the above (1) was molded in the same manner as in Example 1. The thickness of the coating layer of the obtained coated product was about 0.6 mm, and the adhesiveness and appearance of the coating layer were good. The occurrence of warpage was 5 mm.

Example 3 (1) Preparation of coating composition; unsaturated monomer and crosslinkable monomer, respectively 50 parts by weight of methyl methacrylate monomer, 40 parts by weight of methoxytriethylene glycol methacrylate, formula (9) The same procedure as in Example 1 was carried out at 60 ° C. except that the compound represented by the formula was 10 parts by weight and the amount of 2,2 e-azobis (4-methoxy-2,4-dimethylvaleronitrile) was 0.020 part by weight. For 2 hours to obtain a partially cross-linked gel polymer in which the polymer content was increased from 0% by weight to 48% by weight . This polymer was crushed in the same manner as in Example 1, and then blended and kneaded in the same manner as in Example 1 except that 2 parts by weight of 2-methacryloyloxyethyl acid phosphate was added to obtain a thermosetting coating composition. Was. “Crush elongation of cured partially crosslinked gel polymer” is 18
%Met.

(2) Molding of coated article: The composition of the above (1) was molded in the same manner as in Example 1. The thickness of the coating layer of the obtained coated product was about 0.6 mm, and the adhesiveness and appearance of the coating layer were good. The occurrence of warpage was 2 mm.

Comparative Example 1 (1) Preparation of coating composition; methyl methacrylate monomer 95 parts by weight, ethylene glycol dimethacrylate 5 parts by weight, 1,4 (8) -P-menthadiene 0.01 parts by weight, 2,2 et - azobis (4-methoxy-2,4-dimethylvaleronitrile) in 0.1 part by weight were mixed and dissolved Similarly 60 ° C. as in example 1 to about 2 hours polymerized to a polymer content
A partially crosslinked gel-like polymer was obtained in which the weight was increased from 0% by weight to 34% by weight . 100 parts by weight of a composition obtained by crushing this polymer in the same manner as in Example 1, 1 part by weight of methyl methacrylate monomer, 2 parts by weight of 2-methacryloyloxyethyl acid phosphate, and a high-temperature active polymerization initiator 0.1 parts by weight of 2,2-bis (t-butylperoxy) butane, 0.3 parts by weight of di-t-butyl peroxide, and 0.05 parts by weight of di-t-butylperoxyhexahydroterephthalate The composition was obtained by kneading with a sill mixer. "The fracture elongation of the partially crosslinked gel polymer cured product" was 3.8%.

(2) Molding of coated article: The composition of (1) was molded in the same manner as in Example 1. The thickness of the coating layer of the obtained molded article was about 1 mm, and the occurrence of warpage was 33 mm.

[0067]

As described above, the present invention relates to (A) 3 to 60% by weight of a crosslinkable monomer mainly composed of di (meth) acrylate containing at least two urethane bonds and (B) methyl The polymer content of a mixture consisting of 97 to 40% by weight of an unsaturated monomer which is mainly composed of methacrylate and which may contain and dissolve the polymer is adjusted so that the total polymer content does not exceed 80% by weight. Thermosetting coating composition comprising a partially crosslinked gel-like polymer having a polymer content of 4 to 62% by weight higher than the content of the polymer, and the partially crosslinked gel-like polymer or its crushed partially crosslinked gel-like weight United 100
1 part by weight and a syrup containing an unsaturated monomer mainly composed of methyl methacrylate or a polymer thereof dissolved therein.
Because it is a thermosetting coating composition consisting of 100 parts by weight,
The use of this composition is effective in forming a coating layer having excellent adhesiveness because it has the same permeability and fluidity as syrup. Since the handling is easy, the thickness of the coating layer can be freely adjusted, which is particularly suitable for processing a thick coating layer.

The coating resin finally obtained from the coating composition of the present invention has appropriate flexibility and strength.
Even when the coefficient of linear expansion between the resin of the coating layer and the base material coated with the resin is different, it is possible to form a coated product with less warpage.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-136327 (JP, A) JP-A-6-1222837 (JP, A) JP-A-3-247610 (JP, A) JP-A-2- 219811 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09D 4/00 C08F 220/14 C08F 220/36 C08F 299/00 CA (STN) CAOLD (STN) REGISTRY (STN) WPIDS (STN)

Claims (3)

(57) [Claims] 1. A polymer comprising (A) 3 to 60% by weight of a crosslinkable monomer mainly composed of di (meth) acrylate containing at least two urethane bonds and (B) a polymer mainly composed of methyl methacrylate. exist mixture consisting of 97 to 40 wt% may also be unsaturated monomer optionally containing a polymerization initiator
Polymerization by heating in the presence, present in the mixture
Part of the monomer reacts without reacting
Gel-like form obtained by stopping the reaction
Odor of thermosetting coating composition composed of partially crosslinked polymer
The polymer content in the gel-like partially crosslinked polymer (weight
%) Does not exceed 80% by weight, and
4 to 62% by weight than the polymer content (% by weight) in the compound
Thermosetting coating composition characterized as high this. 2. The gel-like partially crosslinked polymer has an average particle size of 5 m.
2. The coating composition according to claim 1, wherein the composition is crushed to less than m. 3. A gel-like partial cross-link according to claim 1 or 2.
Coating composition which is a composition consisting of 100 parts by weight of the polymer and syrup to 100 parts by weight containing dissolved unsaturated monomer or a polymer thereof as a main component methyl methacrylate.