JP3182662B2 - Coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cross-linking composition which is excellent in abrasion resistance, surface smoothness, heat resistance, chemical resistance, durability, weather resistance and adhesion to a substrate by irradiation with active energy rays. The present invention relates to a low-pollution coating composition which forms a film and has substantially no organic solvent or a solid content of 70% or more.

[0002]

2. Description of the Related Art Synthetic resin molded articles manufactured from polymethyl methacrylate resin, polymethacrylimide resin, polycarbonate resin, polystyrene resin, AS resin, etc. are not only lightweight but excellent in impact resistance. In addition, it has good transparency, and in recent years, it has been widely used as a plastic material for automobiles, such as headlamps, glazing, and instrument covers. However, on the other hand, these synthetic resin molded products have insufficient abrasion resistance on the surface, so they are easily damaged by contact with other hard objects, friction, scratches, etc. Improving the wear resistance of the surface is strongly demanded because it significantly lowers the commercial value or makes it unusable in a short period of time. When used as the above-mentioned automotive material, its weather resistance is also an important performance.

[0003] Various methods for improving the disadvantages of such synthetic resin molded articles have been studied in the past.
For example, a method of applying a coating material composed of a silicone-based or melamine-based resin composition to the surface of a synthetic resin molded article, forming a crosslinked film by heat condensation, and improving abrasion resistance, or a method comprising a radical polymerizable monomer There has been proposed a method of forming a crosslinked film by irradiating an active energy ray after applying the resin composition (JP-A-56-122840).

[0004]

However, although the wear resistance of the surface of the synthetic resin molded article is improved to some extent by these methods, the former method has poor durability against heat shock, hot water and the like and chemical resistance. Although the latter method is insufficient, the latter method is excellent in durability and chemical resistance, but is not satisfactory in weather resistance. In particular, when the weather resistance of the base synthetic resin molded article is essentially poor, for example, a polycarbonate resin or the like, even if the weather resistance of the surface-hardened coating film itself is good, the external material that has passed through the coating can be used. The base material itself is deteriorated by active energy rays such as ultraviolet rays from the substrate, and the molded product is strongly yellowed, cracks are generated in the cured film on the surface, and the film is peeled off. Furthermore, in recent years, in order to protect the global environment, the use of high-solid paint has been called for, and there has been an increasing demand for a coating material that balances the workability of coating, the smoothness of the coating, and the performance of the coating. ing.

[0005] The present invention has been made in view of the above background, and aims at abrasion resistance, surface smoothness, and the like.
A crosslinked cured film having excellent heat resistance, chemical resistance, durability, weather resistance and adhesion to a substrate is formed, and contains substantially no organic solvent or has a solid content of 70% or more. It is a low-pollution coating material composition.

[0006]

As a result of intensive studies conducted by the present inventors to solve the above-mentioned problems, a specific polyfunctional (meth) acrylate and a specific bifunctional (meth) acrylate are obtained. By blending the coating compound in a specific ratio, further coating the synthetic resin molded product with a coating material composition in which a UV absorber and a photopolymerization initiator are mixed in a specific ratio, and curing by irradiation with active energy rays. The present inventors have found that a synthetic resin molded article excellent in wear resistance, weather resistance and the like can be obtained, and have reached the present invention.

That is, the present invention relates to (A) a polyfunctional monomer having at least three or more acryloyloxy groups and / or methacryloyloxy groups in one molecule, represented by the following general formula (I): At least one monomer selected from poly (meth) acrylate of polypentaerythritol: 30 to 70 parts by weight,

[0008]

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(Where X ₁₁ , X ₁₂ , X ₁₃ , X ₂₂ , X ₂₃ ...)
At least three of X _n2 , X _n3 , and X ₁₄ are CH ₂ =
A CR-COO- group, and the rest are -OH groups. Also, n
Is an integer of 1 to 5, and R represents hydrogen or a methyl group. (B) at least one of the bifunctional monomers having one acryloyloxy group and / or methacryloyloxy group in one molecule represented by the general formula (II): 20 to 70 parts by weight,

[0010]

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[0011] (wherein, the R ₂ is hydrogen or a methyl group, R ₃
Represents a divalent hydrocarbon group having 1 to 15 carbon atoms. (C) Poly [(meth) acryloyloxyalkyl] (iso) cyanurate represented by formula (III) or (IV): 5 to 50 parts by weight

[0012]

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[0013]

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[0014] (wherein, X _1, X _2, and X ₃ is an acryloyl group, a methacryloyl group, a hydrogen atom or an alkyl group, at least two of these are (meth) acryloyl group, R _1, R ₂ and R ₃ represents an oxyalkylene group having 1 to 4 carbon atoms) (D) ultraviolet absorber:. 2 to 30 parts by weight, (E) a photopolymerization initiator: 0.1 to 10 parts by weight, Ri Tona (However, the total amount of A, B, C, D and E is 1
00 parts by weight), no organic solvent or solid
A coating material composition having a content of 70% or more .

The coating composition is applied to the surface of a synthetic resin molded article, and irradiated with active energy rays, whereby
A synthetic resin molded article having a crosslinked cured film having a thickness of 1 to 30 μm and excellent in wear resistance, heat resistance, chemical resistance, durability and weather resistance can be obtained. The present invention will be described in detail. First, each component of the coating composition of the present invention will be described.

Regarding the component (A), at least one polyfunctional monomer selected from the poly (meth) acrylates of mono- or polypentaerythritol as the component (A) has an active energy of at least one. Upon irradiation with a ray, a polymer having good polymerization activity and having a high crosslinking density and excellent abrasion resistance is formed. Therefore, a cured film having excellent wear resistance can be formed on the surface of the base material.

Specific examples of the component (A) include pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, Dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tripentaerythritol tetra (meth) acrylate Tripentaerythritol penta (meth) acrylate, tripentaerythritol hexa (meth) acrylate, tripentaerythritol hepta (meth) acrylate, tripentaerythritol octa (meth) acrylate Acrylate and the like.

The proportion of the component (A) used is (A) to ( E ).
The amount is 30 to 70 parts by weight, more preferably 40 to 60 parts by weight, per 100 parts by weight of the total amount of the components. If the amount of the component (A) is less than 30 parts by weight, a cured film having sufficient abrasion resistance cannot be obtained, and if it exceeds 70 parts by weight, cracks are easily generated in the cured film, and a durability test and a weather resistance test are performed. Cracks occur in the later cured film. In addition, the heat resistance of the cured film also decreases.

Regarding the component (B), the component (B)
A compound represented by the general formula (II) having two acryloyloxy groups and / or methacryloyloxy groups in one molecule;
The functional monomer is a component that dilutes the high-viscosity component (A) and improves coating workability. Also, with only the component (A),
Since the crosslink density of the cured film becomes too high, it is also a component for appropriately adjusting the crosslink density.

Specific examples of component (B) include ethylene glycol di (meth) acrylate, 1,3-propylene glycol di (meth) acrylate, and 1,4-butylene glycol di (meth) acrylate. Acrylate, 1,5-pentamethylene glycol di (meth) acrylate, 1,6 hexamethylene glycol di (meth) acrylate, 1,3
-Butylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 2-butyne-1,4-di (meth) acrylate, cyclohexane-
1,4-dimethanoldi (meth) acrylate, 1,9
Nonamethylene glycol di (meth) acrylate;
1,14-tetradecandiodiol (meth) acryle
Among them, 1,4-butylene glycol diacrylate and 1,6-hexamethylene glycol diacrylate are particularly preferable.

The proportion of the component (B) used is (A) to ( E ).
The amount is 20 to 70 parts by weight, more preferably 25 to 65 parts by weight, per 100 parts by weight of the total amount of the components. In (B) the amount of the component is less than 20 parts by weight, no sufficient dilution effect is obtained, Painting
Work is lowered. Further, a cured film having sufficient durability and weather resistance cannot be obtained. If it exceeds 70 parts by weight, the abrasion resistance decreases.

Regarding the component (C), the component (C)
Poly ((meta) represented by general formula (III) or (IV)
[Acryloyloxyalkyl] (iso) cyanurate is a component capable of exhibiting good polymerization activity upon irradiation with active energy rays and improving the toughness and heat resistance of a cured film without impairing high abrasion resistance. It is.

Specific examples of the component (C) include di [2-
(Meth) acryloyloxyethyl] isocyanurate, tris [2- (meth) acryloyloxyethyl] isocyanurate, di [2- (meth) acryloyloxypropyl]
Isocyanurate, tris [2- (meth) acryloyloxypropyl] isocyanurate, di [2- (meth) acryloyloxyethyl] cyanurate, tris [2- (meth) acryloyloxyethyl] cyanurate, Di [2
-(Meth) acryloyloxypropyl] cyanurate, tris [2- (meth) acryloyloxypropyl] cyanurate and the like.

The proportion of the component (C) used is (A) to ( E ).
The amount is 5 to 50 parts by weight, more preferably 10 to 40 parts by weight, per 100 parts by weight of the total amount of the components. (C) The amount of the component is 5
If the amount is less than 10 parts by weight, a cured film having sufficient toughness and heat resistance cannot be obtained. If the amount exceeds 50 parts by weight, the abrasion resistance decreases.

With respect to the component (D), the ultraviolet absorbent as the component (D) is not particularly limited, and may be used as long as it is uniformly dissolved in the composition and has good weather resistance. Benzophenone-based, benzotriazo-
Phenyl salicylate, phenyl benzoate derived compounds whose maximum absorption wavelength is 240-
A UV absorber having a wavelength in the range of 380 nm is preferable. In particular, a benzophenone-based UV absorber is preferably used because it can be contained in a large amount in the composition.
Benzotriazole-based ultraviolet absorbers are preferred from the viewpoint that yellowing of a substrate such as a carbonate can be prevented.
Most preferably, these two types are used in combination.

Specific examples of component (D) include 2-hydroxybenzophenone, 5-chloro-2-hydroxybenzophenone, 2,4-dihydroxybenzophenone,
-Hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 2-hydroxy-4-octadecyloxybenzophenone, 2,2'-
Dihydroxy-4-methoxybenzophenone, 2,2 ′
-Dihydroxy-4,4'dimethoxybenzophenone,
Phenyl salicylate, p-tert-butylphenyl salicylate, p- (1,1,3,3-tetramethylbutyl) phenyl salicylate, 3-hydroxyphenylbenzoate, phenylene-1,3- Dibenzoe
2- (2-hydroxy-5'-methylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-tert-butylphenyl) benzotriazole,
-(2-hydroxy-5-tert-butylphenyl)
Benzotriazole, 2- (2-hydroxy-4-octyloxyphenyl) benzotriazole, and the like, among which benzophenone-based 2-hydroxy-
4-octoxybenzophenone, 2,4-dihydroxybenzophenone, benzotriazole-based 2- (2
-Hydroxy-5-tert-butylphenyl) benzotriazole is particularly preferred, and these are more preferably used in combination of two or more.

The proportion of the component (D) used is (A) to ( E ).
It is 2 to 30 parts by weight, more preferably 5 to 15 parts by weight based on 100 parts by weight of the total amount of the components. If the amount of the component (D) is less than 2 parts by weight, the weather resistance of the cured film and the protection of the substrate from ultraviolet rays are not sufficient, and if it exceeds 30 parts by weight, the curing of the film itself becomes insufficient, and The toughness, heat resistance and wear resistance are reduced.

Regarding the component (E), the photopolymerization initiator which is the component (E) includes benzoin, benzoin monomethyl ether, benzoin isopropyl ether, acetoin, benzyl, benzophenone, p-methoxybenzophenone, and diethoxyacetophenone. Benzyldimethylketal, 2,2-diethoxyacetophenone, 1-
Hydroxycyclohexyl phenyl ketone, methyl phenyl glyoxylate, ethyl phenyl glyoxylate
And carbonyl compounds such as 2-hydroxy-2-methyl-1-phenylpropan-1-one; sulfur compounds such as tetramethylthiuram monosulfide and tetramethylthiuram disulfide; and 2,4,6-trimethylbenzoyldiphenylphosphine oxide. And the like. These are used in one kind or in a mixture of two or more kinds. Among them, benzophenone, benzoin isopropyl ether, methylphenylglyoxylate and benzyldimethylketal are more preferred.

The proportion of the component (E) used is (A) to ( E ).
0.1 to 10 parts by weight, more preferably 1 to 5 parts by weight, per 100 parts by weight of the total amount of the components. If the amount of the component (E) is less than 0.1 part by weight, the curability will be insufficient, and if it exceeds 10 parts by weight, coloring of the cured film will occur, and the weather resistance will also decrease.

The coating composition of the present invention may contain an organic solvent, an antioxidant, an anti-yellowing agent, a blueing agent, a pigment, a leveling agent, an antifoaming agent, a thickener, and an anti-settling agent, if necessary. Various additives such as an agent, an antistatic agent and an antifogging agent may be contained. Organic solvent is preferably not used, but the shape of the substrate to be coated, or when a thinner film is required,
Solids, ie, components (A) to (E) that form a cured film
May be added so as not to be less than 70% ( % by weight) . The type of the organic solvent is preferably selected and used depending on the substrate to be coated. That is, when polycarbonate is used as the base material, an alcohol solvent such as isobutanol, n-butyl acetate, diethylene glycol acetate, etc.
It is preferable to use a combination of three kinds of solvents, such as ester solvents such as toluene and cellosolve solvents such as ethyl cellosolve. The amount of the solvent used is 1 to 4 with respect to 100 parts by weight of the coating material composition.
It is preferable to use 0 parts by weight .

As a method for applying the coating composition of the present invention, methods such as brush coating, spray coating, dip coating, spin coating, and curtain coating are used.
The spray coating method is particularly preferred from the viewpoint of improving the coating workability of the coating composition, the smoothness and uniformity of the coating, and the adhesion of the cured coating to the substrate. When the composition is cured by active energy rays, the coating composition is coated on a substrate with a thickness of 1 to 12 μm, preferably 3 to 8 μm, by the above-mentioned coating method.
m and a high pressure mercury lamp, metal halide lamp, etc.
Irradiation is performed at 000 to 5000 mJ / cm ² .
The irradiation atmosphere may be air or an inert gas such as nitrogen or argon.

As the synthetic resin molded article to which the coating composition of the present invention is applied, molded articles of various thermoplastic resins and thermosetting resins which have conventionally been demanded to improve abrasion resistance, weather resistance, etc. is there. Specific examples include polymethyl methacrylic resin, polycarbonate resin, polystyrene resin, ABS
Resin, AS resin, polyamide resin, polyarylate resin, polymethacrylimide resin, polyallyldiglycol
Molded articles such as Luca-bonate resin are exemplified. Here, the molded articles include sheet-shaped molded articles, film-shaped molded articles, various injection molded articles, and the like made of the above resins. Among the above, polymethyl methacrylic resin, polycarbonate resin, polystyrene resin, polymethacrylimide resin,
It is particularly effective for use as a substrate of the coating composition of the present invention because of its excellent transparency and strong demand for improvement of abrasion resistance.

[0033]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples. In the examples, “parts” means “parts by weight”. The measurement and evaluation in the examples were performed by the following methods. (1) The appearance of the cured film, the application of the composition, and the appearance after curing were visually evaluated. …: The surface is smooth and transparent. Δ: The surface has irregularities and is not smooth. ×: Not smooth, whitening or clouding observed.

[0034] (2) S switch abrasion resistance ♯000 - roux - mounting the Le a cylindrical tip of a diameter of 25 mm, with a sample surface placed horizontally, 1Kg
After 50 reciprocal abrasions with a load of, the diffuse transmittance (haze value) was measured to determine the abrasion resistance. Criteria for determining abrasion resistance…: Increased haze value: 0 to 0.5: scarcely scratched. Δ: increased haze value = 0.5 to 3.0: slightly damaged. C: Increased haze value = 3.0 or more: Severely damaged.

(3) Adhesion Cross cuts reaching the substrate at 1 mm intervals are made in the cured film, 100 grids of 1 mm ² are made, a cello tape is stuck on the grid, and the grids are peeled off rapidly and peeled off. Was counted. …: No peeling. Δ: Number of peels 1 to 50 ×: Number of peels 51 to 100

(4) Heat resistance The coated plate sample was placed in a hot air dryer at 120 ° C. for 24 hours.
The appearance of the cured film was observed. ○: No change. Δ: Small cracks occurred. X: Cracks occurred on the entire surface of the coated plate.

(5) Weather Resistance Using a Sunshine Carbon Weatherometer (WEL-SUN-HC-B type manufactured by Suga Test Instruments) weather tester, black panel temperature 63 ± 3 ° C., rainfall 12 minutes, irradiation 48 Tested on a cycle of minutes. 1000 hours, 20
Changes in the cured film after exposure for 00 hours were observed, and the adhesion was tested. (A) Discoloration of appearance ○: No discoloration. Δ: slight yellowing. ×: Large yellowing. (B) Generation of cracks, peeling of film ○: None. ×… Yes.

(Examples 1 to 4, Comparative Examples 1 to 3) A coating material composition was prepared with the components and mixing ratios shown in Table 1. Each of them was spray-coated on a 3 mm-thick polycarbonate resin plate (manufactured by GE, trade name: Lexan LS-II) so that the coating film after curing became 4 μm. afterwards,
Using a high-pressure mercury lamp in air, wavelength 340 nm to 38
Irradiation was performed with an ultraviolet ray of 0 nm so that the integrated light quantity had an energy of 3000 mJ / cm ² to obtain a cured coating film. Table 1 shows the evaluation results of the obtained coating films.

[0039]

[Table 1]

The symbols of the compounds in Table 1 are as follows. DPHA: dipentaerythritol pentaacrylate BDA: 1,4-butylene glycol diol acrylate HDA: 1,6-hexamethylene glycol diol acrylate TAIC: tri (acryloxyethyl) isocyanurate
MPG: methylphenylglyoxylate HBPB: 2- (2-hydroxy-5-tert-butylphenyl) benzotriazole

[0041]

As described above, the coating composition of the present invention has abrasion resistance, heat resistance, weather resistance and chemical resistance by a simple means of irradiating active energy rays such as ultraviolet rays. An excellent synthetic resin cured coated article can be obtained. Therefore, polymethyl methacrylic resin, polycarbonate
It is extremely useful as a coating material for molded articles requiring excellent transparency and improved abrasion resistance, such as a carbonate resin, a polystyrene resin, and a polymethacrylimide resin. Moreover, the coating composition of the present invention does not contain an organic solvent, and thus is effective for environmental protection.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Takashi Kawaguchi 4-160 Sunadabashi, Higashi-ku, Nagoya-shi, Aichi Prefecture Mitsubishi Rayon Co., Ltd. Product Development Research Center (72) Inventor Osamu Takemoto 4-1-1 Sunadabashi, Higashi-ku, Nagoya-shi, Aichi Prefecture No. 60 Mitsubishi Rayon Co., Ltd. Product Development Laboratory (56) References JP-A-2-261831 (JP, A) JP-A-59-98115 (JP, A) JP-A-63-86763 (JP, A) ( 58) Field surveyed (Int. Cl. ⁷ , DB name) C09D 4/02

Claims (1)

(57) [Claims] 1. A polyfunctional monomer having at least three or more acryloyloxy groups and / or methacryloyloxy groups in one molecule, which is a mono- or polypentaerythritol represented by the following general formula (I): At least one monomer selected from the group consisting of poly (meth) acrylates:
0 parts by weight (Where X ₁₁ , X ₁₂ , X ₁₃ , X ₂₂ , X ₂₃ ... X _n2 , X _n3 ,
And X ₁₄ , at least three of which are CH ₂ ＣＲCR ₁ —CO
O-groups and the rest are -OH groups. N is an integer of 1 to 5, and R ₁ represents hydrogen or a methyl group. (B) at least one of the bifunctional monomers having two acryloyloxy groups and / or methacryloyloxy groups in one molecule represented by the general formula (II): 20 to 70 parts by weight, ] (Wherein R ₂ represents hydrogen or a methyl group, and R ₃ has 1 to 1 carbon atoms.
And 15 divalent hydrocarbon groups. (C) Poly [(meth) acryloyloxyalkyl] (iso) cyanurate represented by formula (III) or (IV): 5 to 50 parts by weight Embedded image (Wherein X ₁ , X ₂ and X ₃ represent an acryloyl group, a methacryloyl group, a hydrogen atom or an alkyl group, at least two of which are (meth) acryloyl groups, and R ₁ , R ₂ and R 3 ₃ shows an oxyalkylene group having 1 to 4 carbon atoms) (D) ultraviolet absorber:. 2 to 30 parts by weight, (E) a photopolymerization initiator: 0.1 to 10 parts by weight, Ri Tona (however, The total amount of A, B, C, D and E is 1
00 parts by weight) , no organic solvent or solid
A coating material composition having a content of 70% or more .