JPH04351674A - Coating composition and its cured product - Google Patents

Abstract

PURPOSE:To obtain the title composition which is excellent in abrasion resistance, has a low curing shrinkage and can give a cured product freed from curls and warpages when applied to a sheet or the like by mixing a specified compound with an organic solvent and a photopolymerization initiator as an optional component. CONSTITUTION:A compound of the formula (wherein R is H or CH3) is mixed with an organic solvent (e.g. n-propyl alcohol or xylenol) and a photopolymerization initiator as an optional component (e.g. Irgacure 184, a product of Ciba- Geigy).

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a coating material whose cured product has excellent abrasion resistance, low curing shrinkage, and excellent adhesion to substrates with little curling or warping even when applied to various plastic films and cured. The present invention relates to a composition and a cured product thereof.

0002

[Prior art] Polymethyl methacrylate resin, polycarbonate resin, polyallyl diglycol carbonate resin, polystyrene resin, styrene-acrylonitrile copolymer resin (AS resin), polyvinyl chloride resin, acetate resin, acrylonitrile-butadiene-styrene copolymer resin Synthetic resin molded products made from ABS resin (ABS resin), polyester resin, etc. are not only lighter and have better impact resistance than glass products, but also have various advantages such as being inexpensive and easy to mold. It has organic plate glass,
It is used in mirrors, signboards, displays, screens, and many other areas. The surface of these synthetic resin molded products lacks abrasion resistance, so the surface may be damaged by contact with other objects, collisions, scratches, etc. during transportation, installation, or use of the molded product. This may reduce the yield of the product or impair its aesthetic appearance. Various methods have been studied to improve these drawbacks of synthetic resin molded products, such as applying a coating material made of a polyfunctional acrylate monomer and an organic solvent to the surface of the synthetic resin molded product,
Many methods have been proposed in which a cured film is formed by drying a solvent and then irradiating it with ultraviolet rays. (For example, JP-A-53-10
4638, JP-A-53-102936, JP-A-54-9
7633, JP-A-56-861, etc.)

0003

[Problems to be Solved by the Invention] Coating materials containing polyfunctional acrylate monomers as a main component have excellent abrasion resistance and have not caused any problems in adhesion, etc., but they have large curing shrinkage and are used for various plastics. When used in film products, curling and warping are a major problem.

0004

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present inventors have developed a coating composition containing a specific compound as a result of intensive research and have arrived at the present invention. That is, the present invention

1. Compound (A) represented by formula (1)
,

[0006]

[Case 2]

(In the formula, R is H or CH3.) A coating composition characterized in that it contains an organic solvent (B) and a photopolymerization initiator (C) as an optional component. The present invention relates to a cured product of the coating composition according to item 1.

Next, each component of the coating composition of the present invention will be explained. Specific examples of the compound (A) represented by formula (1) used in the present invention include, for example:

[0009]

[Chemical formula 3]

(manufactured by Nippon Steel Chemical Co., Ltd., cardo epoxy acrylate resin, ASF-400).

Specific examples of the organic solvent (B) used in the present invention include alcohols such as ethanol, isopropanol, normal propanol, isobutyl alcohol, and normal butyl alcohol, and aromatic carbonized solvents such as benzene, toluene, xylene, and ethylbenzene. Examples include hydrogens, ketones such as acetone and methyl ethyl ketone, ethers such as dioxane, and acid esters such as ethyl acetate, n-propyl acetate, n-butyl acetate, and ethyl propionate. These organic solvents may be used alone or in combination of two or more. Depending on the type of synthetic resin used as the base material, these organic solvents may cloud the material used for transparent purposes, elute dyes and pigments from the colored base material, and cause discoloration.
Otherwise, it may cause cracks to occur in the substrate itself, so it is desirable to select the type of organic solvent to be used depending on the type of substrate on which a cured film is to be formed or the purpose. . The amount of the organic solvent (B) used is preferably 10 to 1000 parts by weight, particularly preferably 50 to 500 parts by weight, based on 100 parts by weight of the compound (A) represented by formula (1).

The cured product of the coating composition of the present invention can be obtained by irradiating it with ultraviolet rays or electron beams and curing it in a conventional manner. For example, the coating composition of the present invention is applied to the surface of a synthetic resin molded article, and active energy rays such as ultraviolet rays, electron beams, or radiation are irradiated to form a cured film. Among these, the method using ultraviolet irradiation is the most preferred curing method from a practical standpoint.

When ultraviolet rays are used as energy rays for curing the coated film, it is preferable to add a photopolymerization initiator (C) capable of initiating a polymerization reaction upon irradiation with ultraviolet rays to the coating composition. Such a photoinitiator (C)
Specific examples include benzyl dimethyl ketal,
Examples include 1-hydroxycyclohexylphenylketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzophenone, and 2,2-diethoxyacetophenone. These photopolymerization initiators (C) may be used alone or in combination of two or more. The amount of these photopolymerization initiators (C) added to the coating composition is preferably 0 to 20 parts by weight, particularly preferably 0.01 to 10 parts by weight, per 100 parts by weight of component (A).

[0014] The coating composition of the present invention contains each component at room temperature to 80°C.
It can be obtained by mixing and dissolving at ℃.

The coating composition of the present invention may further contain tetrahydro(meth)acrylate, acryloylmorpholine, isobornyl(meth)acrylate, neopentyl hydroxypivalate glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, if necessary. Reactive monomers such as acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta and hexa(meth)acrylate, light stabilizers (e.g. hindered amine type), ultraviolet absorbers, Antioxidants, leveling agents, antistatic agents, surfactants, polymerization inhibitors, etc. can be used.

Next, manufacturing a wear-resistant synthetic resin molded article using the above-mentioned coating composition involves applying the coating composition of the present invention to the surface of the synthetic resin molding and then irradiating it with active energy rays. Manufactured by. The synthetic resin molded products used when manufacturing wear-resistant synthetic resin molded products using the coating composition of the present invention include various synthetic resin molded products, regardless of thermoplastic resin or thermosetting resin, such as polyester resin molded products. Sheet molding made from methyl methacrylate resin, polycarbonate resin, polyallyl diglycol carbonate resin, polystyrene resin, acrylonitrile-styrene copolymer resin (AS resin), polyvinyl chloride resin, acetate resin, ABS resin, polyester resin, etc. Specific examples include molded products, film-shaped molded products, rod-shaped molded products, and various injection molded products. The various molded products described above can be used as they are, but if necessary, they may be cleaned, etched, corona discharged, irradiated with active energy rays, etc.
Materials that have undergone pretreatment such as dyeing or printing can also be used. Further, as a method for applying the coating composition of the present invention to a synthetic resin molded article, methods such as brush coating, flow coating, spray coating, spin coating, and dip coating are employed. Each method has its advantages and disadvantages, and it is preferable to select the coating method depending on the required performance of the synthetic resin molded article or its intended use. The amount of the coating composition to be applied to the surface of the synthetic resin molded article varies depending on the amount of volatile matter contained in the coating composition and the purpose, but it depends on the thickness of the cured film formed on the surface of the synthetic resin molded article. It is preferable to apply the coating so that the thickness is in the range of 1 to 30 μm. In addition, depending on the use of synthetic resin molded products with a hardened film formed on the surface, after the hardened film has been formed, bending under appropriate heating, cutting, drilling, etc. may be performed, or parts may be attached. It is required to withstand severe conditions such as being subjected to large deformation strains at times or during use. In such a case, it is necessary that the cured film itself has excellent properties such as flexibility and adhesion to the base resin, and the second factor is the thickness of the cured film. In other words, the thinner the film thickness, the more preferable it is, but as it becomes thinner, the abrasion resistance decreases, so in such a case, it is preferable to keep the thickness of the cured film in the range of 1 to 9 μm, taking into consideration the balance. .

In the step of irradiating active energy rays, the coating film applied to the surface of the synthetic resin molded product is cured by irradiating the coating film with activation energy rays. Preferably, a specific coating film is applied before curing with active energy rays. It is better to volatilize 50% by weight or more of the organic solvent (B) contained in the film of the coating composition applied to the surface of the synthetic resin molded article under conditions, and then irradiate it with active energy rays. In order to cure the coated film, specifically, ultraviolet rays emitted from a light source such as a xenon lamp, low pressure mercury lamp, medium pressure mercury lamp, high pressure mercury lamp, or super pressure mercury lamp, or an electron beam taken out from an electron beam accelerator of usually 20 to 2000 KV are used. , irradiation with active energy rays such as alpha, beta, and gamma rays.

[0018]

[Examples] The present invention will now be explained in more detail with reference to Examples. Examples 1 to 4, Comparative Example 1 A coating composition of the present invention was prepared by mixing each compounding component according to the formulation shown in Table 1 (values are expressed in parts by weight), and a coating composition of the present invention with a thickness of 0.1 mm was prepared. After the methacrylic resin sheet was immersed, the coating composition was slowly pulled up to form a coating film on the surface of the sheet. Then add 5 organic solvents
Volatize for 5 minutes at 0°C and apply ultraviolet light (2KW high pressure mercury lamp)
was irradiated to form a cured film with a thickness of about 5 μm on the surface of the sheet. Various performance evaluations (pencil hardness, steel wool abrasion test, presence or absence of adhesion curl) were conducted and the same Table 1 was conducted.
It was shown to.

Pencil hardness Steel wool scratch test in accordance with JIS K5651-1966 Steel wool #0000 was used to rub the surface of the cured film and the degree of scratches was evaluated. ○...No scratches even when rubbed hard △...Slight scratches occur when rubbed hard, no scratches even when rubbed weakly×...Scratch occurs even when rubbed weakly

[0020] Cuts were made in the adhesive cured film to cut into 100 square pieces of 1 mm on each side, and cellophane tape was attached to the surface and immediately removed. It was expressed by the number of small pieces of the cured film remaining at that time. The larger the number, the better the adhesion.

0021: Occurrence of curl ○... Hardly any occurrence of curl or warp △... Slight occurrence of curl or warpage ×... Large amount of curl or warpage

[0022]
Table 1

Implementation example Comparative example
1 2
3 4*4 1(A) Component AS
F-400*1 35 33
28 35(B) Component n-propyl alcohol 55 55 55
55 55 Xylene 10 10
10 10 10 (C) Component
Irgacure 184 *2 1.7 1.
7 1.7 1.
7 KAYARAD DPHA*3

5 33
Tetrahydrofurfuryl acrylate
2 2
2 Pencil hard
degree 8H 8H 8
H 7H 8H Steel wool abrasion test ○ ○
○ ○ ○
Adhesion 100/
100 100/100 100/100 100/1
00 100/100 Curl formation ○ ○
○ ○ ×

[0023]
Note *1 ASE-400: Manufactured by Nippon Steel Chemical Co., Ltd.
Compound of formula (2), cardo epoxy acrylate resin *2 Irgacure-184: manufactured by Ciba Geigy,
Photoinitiator *3 KAYARAD DPHA: Nippon Kayaku Co., Ltd.
Co., Ltd., dipentaerythritol penta and hexaacrylate mixture *4 Example 4 was cured using an electron beam accelerator (175 KeV
) and was cured by irradiation with an electron beam.

[0024]

[Effects of the Invention] The cured product of the coating composition of the present invention has excellent abrasion resistance and small curing shrinkage, and when applied to various plastic sheets or film products and cured, curling and warping do not occur. I can't do it.

Claims (2)

[Claims] Claim 1: A compound (A) represented by formula (1), [Chemical formula 1]
] (In the formula, R is H or CH3.) Organic solvent (B)
and a coating composition comprising a photopolymerization initiator (C) as an optional component. 2. A cured product of the coating composition according to claim 1.