JP2797402B2 - Coating composition and molded article coated with the same - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a coating composition, for example, a coating composition for protecting plastic moldings.

[Conventional technology]

Plastic molded products are used in large quantities, taking advantage of their advantages such as light weight, easy processability, and impact resistance, but on the other hand, they have insufficient hardness and are easily damaged, are easily eroded by solvents, and are charged with dust. It has drawbacks such as adsorption of heat and insufficient heat resistance, and has been practically unsatisfactory in comparison with inorganic glass molded articles when used as eyeglass lenses or window materials.

Therefore, it has been proposed to apply a protective coat to a plastic molded product. Numerous types of coating compositions for use in coatings have been proposed. Among them, there is a “coating composition containing an organosilicon compound or a hydrolyzate thereof as a main component (resin component or coating film forming component)” which is expected to give a hard coating film close to an inorganic type (for example, This is practically used for eyeglass lenses.

However, this coating composition is still unsatisfactory in abrasion resistance (scratch resistance). Therefore, a composition in which silica sol dispersed in a colloidal form is added thereto has been proposed (see, for example, JP-A-53-111336). This is also put to practical use for eyeglass lenses.

Conventionally, almost 100% of plastic glasses lenses have been manufactured by casting polymerization of a monomer called diethylene glycol bisallyl carbonate (commonly called CR-39). This lens has a refractive index of about 1.50, which is lower than the refractive index of a glass lens of about 1.52. Had become.

Therefore, the development of monomers higher than CR-39 has been promoted, for example, JP-A-55-13747, JP-A-56-166214,
JP-A-57-23611 and JP-A-57-54901 have been proposed. At present, several companies have commercialized plastic lenses having a medium to high refractive index of n _d = 1.54 to 1.60.

These lenses are also coated with the coating composition containing the silica sol.

[Problems to be solved by the invention]

However, the coating composition to which the silica sol is added has a first problem that an interference image is seen in the coating film and the appearance of the lens is poor.

In addition, in many lenses, an antireflection film (consisting of a multilayer structure film of an inorganic oxide thin film based on the theory of optical interference) is formed on a coating film. In this case, the antireflection film exhibits, for example, an extremely light green reflection color, but this reflection color changes according to the position of the lens surface, and there is a second problem that there is unevenness.

Accordingly, a first object of the present invention is to provide a coating film in which no interference fringe is visible and the reflection color is not uneven for a medium to high refractive index plastic product where n _d = 1.54 to 1.60. It is to provide a coating composition.

The second object of the present invention is to provide abrasion resistance, surface hardness,
An object of the present invention is to provide a coating composition excellent in abrasion resistance, flexibility, transparency, antistatic property, dyeability, heat resistance and the like.

[Means for solving the problem]

Therefore, the present invention provides: (a) a general formula: R ¹ _a R ² _b Si (OR ³ ) _{4- (a + b)} (formula I) (wherein, R ¹ has an epoxy group an organic group or an organic group having 4 to 14 carbon atoms and having an unsaturated double bond, R ² is a hydrocarbon group or a halogenated hydrocarbon group having 1 to 6 carbon atoms, R ³ is C 1 -C A to b are each 0 or 1, and a + b
Is 1 or 2. Or (b) an alkali metal salt of an oxygen acid of a metal selected from the group consisting of titanium, zirconium, hafnium, niobium, tantalum, molybdenum and tungsten, or also alkaline earths. A sol formed by dispersing a metal salt or a lead salt in the form of a colloid in a dispersion medium; and a molded article having a transparent coating layer formed by applying the coating composition.

[Action]

Description of the component (a): Among the compounds of the general formula (I), when R ¹ has an epoxy group as a functional group, for example, the following compounds are used.

(1) General formula (II): (Where R ⁴ is an alkyl group or alkoxyalkyl group or an acyl group having 1 to 4 carbon atoms, R ⁵ is a hydrocarbon group or a halogenated hydrocarbon group having 1 to 6 carbon atoms, and R ⁶ is a hydrogen atom. Or a methyl group, m is 2 or 3, p is 1 to 6, and q is 0 to 2.)

(2) General formula (III): (However, R ⁷ is an alkyl group or an alkoxyalkyl group or an acyl group having 1 to 4 carbon atoms, R ⁵ is a hydrocarbon group or a halogenated hydrocarbon group having 1 to 4 carbon atoms, 1 is 2 or 3, r Is 1-4.) A compound represented by the formula:

Since all of the compounds represented by the above general formula have an epoxy group, they are also called epoxysilane.

Specific examples of epoxy silane include, for example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltris (methoxyethoxy) silane, γ-glycidoxypropyltrimethoxysilane. Examples include acetoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β- (3,4-epoxycyclohexyl) ethyltriethoxysilane.

Further, among the compounds of the general formula (I), those other than those in which R ¹ has an epoxy group as a functional group (including those in which a = 0)
For example, the following is used.

Methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyltris (methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, aminomethyltrimethoxysilane, 3-amino Propyltrimethoxysilane, 3-aminopropyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, 3,3,3-trifluoropropyl Various trialkoxysilanes such as trimethoxysilane, trisiloxysilane or tris (alkoxyalkoxy) silane compounds.

All of the exemplified compounds of the general formula (I) described above are
This is an example of a trifunctional compound having three OR ³ groups (a + b = 1) bonded to a Si atom, but a bifunctional compound having two OR ³ groups (a + b = 2) can of course also be used. .
Examples of bifunctional equivalent compounds include dimethyldimethoxysilane, diphenyldimethoxysilane, methylphenyldimethoxysilane, methylvinyldimethoxysilane, dimethyldiethoxysilane, and the like.

The compound of the general formula (I) may be used alone,
Two or more kinds may be mixed and used according to the purpose.

In particular, when a bifunctional compound is used, it is preferable to use it in combination with a trifunctional compound. When used together,
On average, 2> a + b> 1.

Furthermore, it is also possible to use a tetrafunctional equivalent compound in which a = b = 0. Examples of tetrafunctional corresponding compounds include methyl silicate, ethyl silicate, isopropyl silicate, n-propyl silicate, n-butyl silicate, t-butyl silicate, sec-butyl silicate and the like.

The compound of the general formula (I) may be used as it is, but is preferably used as a hydrolyzate for the purpose of increasing the reaction rate and lowering the curing temperature. When two or more compounds having the same functional number are used in combination of two to four functional compounds, or two or more compounds having different functional numbers are used in combination,
They may be used together after hydrolysis or may be used together before hydrolysis to carry out co-hydrolysis. Upon hydrolysis, the alcohol HOR ³ is released, and the compound of general formula (I) corresponds to become. Silanol rapidly undergoes dehydration condensation to become an oligomer. Therefore, for this reaction to proceed sufficiently,
After the water separation, the mixture may be left (cured) for 1 to 24 hours.

(B) Description of the component: The colloidally dispersed substance is a kind of salt,
Particularly, it is a salt of an oxygen acid of a predetermined metal.

The predetermined metal is, as described, a metal selected from the group consisting of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten.

As an alkali for forming a salt with an oxyacid of these metals, alkali metals such as lithium, sodium, potassium, rubidium and cesium, and alkaline earth metals such as magnesium, potassium, strontium, barium and lead are used.

 Some examples of such salts are given below.

Li ₂ Ti O ₃ , LiNbO ₃ , CaZrO ₃ , CaNb ₂ O _6, SrTiO ₃ , SrTa ₂ O _6, BaTi
O ₃ , BaMoO ₄ , K ₂ WO _4, PbWO ₄ Sr (Ti, Zr) O ₃ , Ba (Ti, Zr) O ₃ ,
(Ba, Sr) TiO ₃ etc.

These salts are used in the form of colloidal dispersion (generally called sol) in a dispersion medium such as water, alcohol or another organic solvent, or a mixed solution of water and an organic solvent in the form of solid fine particles. It is preferable to add, for example, an organic amine or other stabilizer to the sol.

The particle diameter of the fine particles is preferably from 1 to 200 mμ, particularly preferably from 5 to 100 mμ. If it is smaller than this, it is difficult to manufacture, the stability of the sol itself is poor, and the effect is small.If it is larger than this, the stability of the coating composition, the transparency of the coating film,
Smoothness etc. decrease.

Such a sol itself is partially known and partially available as a commercial product.

Description of Component (c): The curing catalyst (c) is used as necessary to shorten the time required for polymerizing the component (a) to form a three-dimensional network coating film ( However, those that impair the stability of the coating composition are not preferred),
For example, the following is used.

(1) Amines: monoethanolamine, diethanolamine, isopropanolamine, ethylenediamine, isopropylamine, diisopropylamine, morpholine, triethanolamine, diaminopropane, aminoethylethanolamine, dicyandiamide, triethylenediamine,
2-ethyl-4-methylimidazole.

(2) Various metal complex compounds: General formula: AlX _n Y _3-n (where X is OL (L is a lower alkyl group), Y is general formula M ¹ COCH ₂ COM ² (M ¹ , M ² Is a lower alkyl group) and M ¹ COC
At least one selected from ligands derived from H ₂ COOM ² and n is 0, 1 or 2).

Particularly useful chelate compounds include aluminum acetylacetonate, aluminum bisethylacetoacetate monoacetylacetonate, aluminum-di-n-butoxide-monoethylacetoacetate, and aluminum-acetylacetonate from the viewpoint of solubility, stability, and catalytic effect. Di-iso-propoxide monomethyl acetoacetate.

In addition, chromium acetylacetonate, titanyl acetylacetonate, cobalt acetylacetonate, iron (III) acetylacetonate, manganese acetylacetonate, nickel acetylacetonate.

(3) Metal alkoxide: aluminum triethoxide, aluminum tri n-
Propoxide, aluminum tri-n-butoxide, tetraethoxy titanium, tetra n-butoxy titanium, tetra i
-Titanium propoxy.

(4) Organic metal salts: sodium acetate, zinc naphthenate, cobalt naphthenate, zinc octylate, tin octylate.

(5) Perchlorates: magnesium perchlorate and ammonium perchlorate.

(6) Organic acids or anhydrides: malonic acid, succinic acid, tartaric acid, adipic acid, azelaic acid, maleic acid, O-phthalic acid, terephthalic acid, fumaric acid, itaconic acid, oxaloacetic acid, succinic anhydride, maleic anhydride Acid, itaconic anhydride, 1,2-dimethylmaleic anhydride, phthalic anhydride, hexahydrophthalic anhydride, naphthalic anhydride.

(7) Lewis acid: ferric chloride, aluminum chloride.

(8) Metal halides: stannous chloride, stannic chloride, tin bromide, zinc chloride,
Zinc bromide, titanium tetrachloride, titanium bromide, thallium bromide,
Germanium chloride, hafnium chloride, lead chloride, lead bromide.

The above catalysts may be used alone or in combination of two or more. In particular, when the component (a) has an epoxy group, one that also functions as a ring-opening polymerization catalyst for the epoxy group may be used.

In particular, an aluminum chelate compound is one of the preferred catalysts.

Description of Component (d): The solvent (d) is used as necessary to make the coating composition liquid or to lower the viscosity.
For example, water, lower alcohol, acetone, ether, ketone, ester and the like are used.

In the coating composition of the present invention, the component (b) is used in an amount of 1 to 500 parts by weight (solid content), preferably 10 to 2 parts per 100 parts by weight (solid content) of the component (a).
0.0000 to 50 parts by weight, preferably 0.0005 to 20 parts by weight of the component (c) per 100 parts by weight (solids) of the components (a) and (b). Is appropriate.

The component (d) is used in an appropriate amount depending on the viscosity of the composition.

In addition to the above components (a) to (d), if necessary, for example, improvement in adhesion to a substrate (molded product) on the side to be coated,
Various additives may be used in combination for the purpose of improving the weather resistance or for improving the stability of the coating composition.

Examples of additives include pH adjusters, viscosity improvers, leveling agents, matting agents, dyes, pigments, stabilizers, UV absorbers, antioxidants, and the like.

In addition, an epoxy resin or another organic polymer may be used in combination for the purpose of improving the dyeability of the coating film. Epoxy resins include alicyclic epoxy resins such as polyolefin epoxy, cyclopentadiene oxide, cyclohexene oxide or polyglycidyl ester, polyglycidyl ether, epoxidized vegetable oil, and novolak type, which are widely used for coatings and casting. Epoxy novolaks composed of phenolic resin and epichlorohydrin, as well as glycidyl methacrylate and methyl methacrylate copolymers are available.

Other organic polymers include, for example, polyols, cellulose resins, melamine resins, and the like.

Various surfactants can be used in combination with the coating composition for the purpose of improving the flow at the time of application, improving the smoothness of the coating film and reducing the friction coefficient of the coating film surface, and in particular, dimethyl siloxane A block or graft copolymer of styrene and an alkylene oxide, and a fluorine-based surfactant are effective.

In some cases, inorganic fillers such as silica sol, antimony acid sol, and diamond fine particles may be used in combination as long as the object of the present invention is not impaired.

The compositions according to the invention are applied in particular to plastic moldings. Speaking of the molded product from the material, for example, polymethyl methacrylate and its copolymer, acrylonitrile styrene copolymer, polycarbonate, cellulose acetate, polyvinyl chloride, polyethylene terephthalate,
The composition of the present invention is applied to an epoxy resin, an unsaturated polyester resin, a polyurethane resin, a polymer of CR-39, and the like.

In terms of the form of the product, the composition of the present invention is applied to a soul, a wire, a film, and the like.

In terms of the function of the molded product, the composition of the present invention is applied to optical products, particularly camera lenses, eyeglass lenses, reflectors, prisms and the like.

The composition of the present invention is particularly useful as an anti-scratch film for “glass lenses” formed of a resin having a medium to high refractive index of n _d = 1.53 or more.

In addition, the composition of the present invention is not limited to plastic molded articles, and can be applied to inorganic glass, wood, metal articles, and the like.

As a coating means, a normal coating method such as brush coating, dipping, roll coating, spray coating, and flow coating can be used.

Furthermore, after applying the composition of the present invention to a mold, the raw material to be a substrate molded product is cast and polymerized to form a plastic molded product, or after the composition of the present invention is applied to the molded product, it is still cured. An uncoated film surface can be brought into close contact with a mold, and the coating film can be cured thereon.

After being applied, the coating composition of the present invention is often cured by heat treatment to obtain a hard coating film. Heating temperature up to about 50-200 ° C, preferably 80-140 ° C
Can provide a sufficient effect.

The thickness of the coating is generally 0.3-30 μm after drying, preferably
0.5 to 10μ is sufficient.

The coating film is transparent and excellent in hardness, especially scratch resistance, and does not cause deterioration in appearance due to scratches, which is a problem of plastic molded products, and can provide molded products with extremely high commercial value.

Hereinafter, the present invention will be described more specifically with reference to the present invention, but the present invention is not limited thereto.

[Examples 1 to 6] (1) Preparation of Preliminary Composition A: 212.4 parts by weight of γ-glycidoxypropylmethyltrimethoxysilane was charged into a reaction vessel equipped with a rotor.
48.6 parts by weight of a 0.01 N hydrochloric acid aqueous solution was gradually added while vigorously stirring with a magnetic stirrer while cooling to ° C.

Immediately after the completion of the dropping, the cooling was stopped to obtain a uniform, colorless and transparent solution-like hydrolyzate corresponding to the component (a).

To the obtained hydrolyzate (a), 77.1 parts by weight of ethanol and 37.7 parts by weight of ethylene glycol are added as components (d), and then 7.65 parts by weight of aluminum acetylacetonate is added as component (c), and the mixture is sufficiently mixed and dissolved. Let me
Preparatory composition A was prepared.

(2) Preparation of Preliminary Composition B: 248 parts by weight of γ-glycidoxypropyldiethoxysilane was charged into a reaction vessel equipped with a rotor, and while stirring vigorously using a magnetic stirrer, a 0.05 N hydrochloric acid aqueous solution 36 was added. Parts by weight were added at once. Immediately after the addition, the solution was a heterogeneous solution, but became a uniform, colorless and transparent solution while generating heat within a few minutes. Stirring was further continued for 1 hour to obtain a hydrolyzate corresponding to the component (a).

To the obtained hydrolyzate (a), 56.6 parts by weight of ethanol and 53.4 parts by weight of ethylene glycol were added as components (d), and then 4.7 parts by weight of aluminum acetylacetonate was added as component (c), followed by thorough mixing and dissolution. Let me
Preparatory composition B was prepared.

(3) Preparation of coating composition: The preparatory compositions A and B prepared in the above (1) and (2) were weighed and poured into a glass container in a weight part (not a solid content) shown in Table 1 below. BaTiO ₃ barium titanate sol (water dispersion sol, average particle size: 8mμ, solid content 15-20
%) And 0.45 parts by weight of a silicone-based surfactant were added, and the mixture was sufficiently stirred and mixed to prepare a uniform, colorless and transparent solution-like coating composition.

(4) Coating: A commercially available polycarbonate-based glasses lens (diameter 70 mm) having a refractive index n _d = 1.59 is prepared and immersed in the lens (pulling speed).
The coating composition was applied at a rate of 10 cm / min) and heated at 100 ° C. for 2 hours to cure the coating.

(5) Evaluation: The lens with the cured coating film obtained in (4) above was subjected to the following test to evaluate the performance of the coating film.

(A) Friction resistance test The surface of the coating film was rubbed with steel wool # 0000, and the scratch resistance was examined. In addition, evaluation was performed as follows.

 ◎: No scratches even with strong friction.

 …: Slightly scratched when rubbed quite strongly.

 ×: Scratches even with weak friction.

 Incidentally, the evaluation of the lens without the coating film was x.

(B) Appearance A general-purpose anti-reflection film was formed on the coating film cured in the above item (4) by a vacuum deposition method, and the unevenness of the reflection color was visually observed, and evaluated as follows.

◎… No irregularities in reflected color ○ …… あ り Slightly present × …… 著 し い Marked (c) Adhesion After immersing the lens with the cured coating film in hot water at 90 ° C for 2 hours, apply a 1mm knife to the coating film surface. 100 goban eyes were made by inserting cut lines in the vertical and horizontal directions every time, and then a cellophane adhesive tape (trade name "Cellotape" manufactured by Nichiban Co., Ltd.) was strongly attached. With one end of the tape in hand, the tape was rapidly peeled off in the direction of 90 degrees, and the number of peeled goban eyes on the coating film was examined. The number X of the eyes of the peeled goban is expressed as X / 100 with the numerator as the numerator. The smaller the X, the better the adhesion.

(D) Dyeability The lens having the cured coating film was immersed in a dispersion paint (mixed three colors of red, yellow, and blue) bath at 90 ° C. for 30 minutes, and the degree of dyeing was measured by light transmittance.

 The results of the above evaluations are shown in Table 1 below.

(Comparative example)

In the examples, barium titanate sol was replaced with a commercially available silica sol (methanol dispersion sol, average particle diameter: 13
A coating composition of this example was prepared and evaluated in substantially the same manner as in the example, except that ± 1 μm, solid content 20%) was used.

 The results of the above evaluations are shown in Table 1 below.

Example 7 Methylmethoxysilane 13 was placed in a reaction vessel equipped with a rotor.
6 parts by weight were charged, and 54 parts by weight of a 0.01 N hydrochloric acid aqueous solution was added at a time, and stirring was continued until the contents heated and cooled to room temperature to obtain a hydrolyzate.

To 85 parts by weight of this hydrolyzate, 52 parts by weight of a hydrolyzate of γ-glycidoxypropylmethyltrimethoxysilane hydrolyzed in the same manner as in Example 1, 43 parts by weight of n-propyl alcohol, and 1 drop of a silicone surfactant (About 0.05 parts by weight) and 6 parts by weight of aluminum acetylacetonate,
By sufficiently mixing and dissolving, Preparatory Composition C was prepared.

To this preliminary product C, 360 LiNbO ₃ lithium niobate sol (water-dispersed sol, average particle diameter: 60 mμ, solid content: 16%) was added in 360 parts.
The coating composition in the form of a uniform, colorless and transparent solution was prepared by adding parts by weight (not the solid content) and sufficiently stirring and mixing.

When this composition was evaluated in the same manner as in Example 1, similarly good results were obtained.

〔The invention's effect〕

As described above, according to the present invention, a coating composition having the following characteristics can be obtained.

(1) When a hard coating film is formed by applying to a medium to high refractive index plastic glasses lens and an antireflection film is formed thereon, there is no uneven reflection.

(2) scratch resistance, surface hardness, abrasion resistance, flexibility,
Excellent transparency and heat resistance.

(3) The elongation of the coating film is large, and the risk of crack generation on the coating film surface is extremely small even when the substrate is bent.

(4) There is no trouble such as curling when the film is applied to a thin film with a small shrinkage upon curing.

(5) The coating film has an excellent antistatic property and is relatively hard to stain.

(6) The coating film can be dyed with a disperse dye.

(7) The surface reflectance of the coating film is large.

(8) Adhesion of an antireflection film, a metal deposition film and the like to the coating film is good.

(9) Good sliding properties on the coating film surface (low friction coefficient).

(10) Excellent flame retardancy.

Claims (2)

(57) [Claims] 1. A general formula: R ¹ _a R ² _b Si (OR ³ ) _{4- (a + b)} (formula I) (wherein, R ¹ is an organic group having an epoxy group or an organic group of 4-14 carbon atoms and having an unsaturated double bond, R ²
Is a hydrocarbon group having 1 to 6 carbon atoms or a halogenated hydrocarbon group, R ³ is an alkyl group having 1 to 4 carbon atoms, an alkoxyalkyl group or an acyl group, and a and b are each 0 or 1, and a + b is 1 or 2. Or (b) an alkali metal salt of an oxygen acid of a metal selected from the group consisting of titanium, zirconium, hafnium, niobium, tantalum, molybdenum and tungsten, or also alkaline earths. A coating composition comprising a sol obtained by dispersing a metal salt or a lead salt in a colloidal state in a dispersion medium. 2. A molded article having a transparent coating layer, wherein the transparent coating layer is a cured layer formed by applying the following coating composition. (A) General formula: R ¹ _a R ² _b Si (OR ³ ) _{4- (a + b)} (formula I) (wherein, R ¹ is an organic group having an epoxy group or an unsaturated group) an organic group of 4-14 carbon atoms having a double bond, R ²
Is a hydrocarbon group having 1 to 6 carbon atoms or a halogenated hydrocarbon group, R ³ is an alkyl group having 1 to 4 carbon atoms, an alkoxyalkyl group or an acyl group, and a and b are each 0 or 1, and a + b is 1 or 2. Or (b) an alkali metal salt of an oxygen acid of a metal selected from the group consisting of titanium, zirconium, hafnium, niobium, tantalum, molybdenum and tungsten, or also alkaline earths. A sol formed by dispersing a metal salt or a lead salt in a colloidal form in a dispersion medium;