JPH0214274A - Coating composition of high refractive index and molded plastic product provided with coating film thereof - Google Patents

Abstract

PURPOSE:To obtain the subject coating composition, consisting of a specific compound and organosilicon compound, excellent in impact, chemical, scuff resistance, adhesive properties and flexibility and capable of providing films having a high refractive index by application thereof to various substrates. CONSTITUTION:The objective coating composition consisting of (A) at least one of compound having recurring units expressed by the formula (X and Y are halogen except fluorine, methyl, ethyl or methoxy; a and b are 0-4) (e.g., consisting of a polymer having 3000-110000 weight-average molecular weight) or further (B) at least one of an organosilicon compound expressed by the formula R<1>cR<2>aSiZ4-(c+d) (R<1> and R<2> are 1-16C organic group; Z is hydrolyzable functional organic group; c and d are 0-3 and 0<=c+d<=3) or a hydrolyzate of the afore-mentioned compound. A film consisting of the above-mentioned coating composition is formed on at least one surface of a plastic substrate to afford the objective molded plastic product.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention has excellent impact resistance, chemical resistance, adhesion, scratch resistance, and flexibility, and can be applied to various base materials. The present invention relates to a high refractive index coating composition that provides a coating film with a high refractive index, and to a plastic molded article provided with the coating film.

[Prior Art] Conventionally, Plus Deck molded products have been used in a wide variety of fields, taking advantage of their advantages such as light weight, impact resistance, and ease of workability. In particular, in addition to the above-mentioned properties, transparent plastics also have excellent dyeability, so their applications as optical components such as glass lenses are being expanded. However, plastic molded products are easily stained by household products such as ink, cosmetics, and soy sauce, and are also susceptible to chemicals such as hair spray, hair tonic, and cologne. moreover,
The actual situation is that the range of use is quite limited because it has drawbacks such as being easily scratched due to insufficient surface hardness.

Therefore, as a means of improving these shortcomings.

Many proposals have been made regarding improvements to the plastic itself, as well as methods using various coatings, but these have not always been fully satisfactory.

For example, a small combination of diethylene glycol bisallyl carbonate "CR-39" (trade name of PBG Co., Ltd.) is known as an improvement of plastic itself, and compared to conventional plastics, it has better chemical resistance, heat resistance, The surface hardness has been greatly improved and it has been applied to eyeglass lenses, windshields, etc., but the surface hardness is low and easily scratched, so further improvement is desired.

On the other hand, as a coating method, for example, Japanese Patent Publication No. 51-2343 discloses a composition consisting of an alkyltrialkoxysilane hydrolyzate and a specific metal salt such as sodium. There were drawbacks such as salt bleed out onto the surface. Furthermore, a composition obtained by combining an epoxy group-containing alkoxysilane or silane hydrolyzate with an epoxy resin is disclosed in JP-A-52-112698. Tokuko Sho 55-291
02.57-. Although these are disclosed in various publications such as No. 42665, they have poor resistance to chemicals such as ink, and furthermore, have poor water resistance. As an improvement on this, a composition using a trace amount of metal halide of Group IV of the periodic table, Alcolade, etc. has been proposed in JP-A-58-125764, but it has problems in liquid life and long-term water resistance.

In addition, compositions consisting of alkoxysilane and colloidal silica, compositions consisting of polyfunctional silane, reactive silane and colloidal silica, and coordination compounds of aluminum are also used to improve the disadvantages of such compositions. Many compositions have been proposed, including compositions containing. Then,
Many of the coating films made from these compositions have drawbacks such as insufficient hardness, poor heat stability, low adhesion, and discoloration, and they also require a long time to form and are difficult to handle. There are problems such as difficulty in

In particular, in recent years, there has been a demand for higher refractive index of plastics as substrates, and as this has been put into practical use, the refractive index of coating compositions made of organosilicon compounds as shown above has become lower than that of substrates. Due to the large difference and uneven application of the composition, a new problem has arisen in that interference fringes occur due to differences in film thickness, which impairs the appearance. In order to solve this problem, a coating composition consisting of Ii antimony oxide sol, a hydrolyzate of an organosilicon compound, and a cured epoxy resin was developed.
No. 54331 is disclosed in the Bow Publication, but it still does not completely eliminate interference fringes, and the hardness and dyeability of the coating film are not compatible. Furthermore, Japanese Patent Laid-Open No. 6211801 proposes to eliminate interference fringes by providing a liquid anti-reflection IV layer between the substrate and the coating layer of the coating composition, but this method requires a complicated process called brimer treatment. This method requires 300 nm, which reduces workability, and also has problems with adhesion.Furthermore, it does not cover the entire visible light range in terms of refractive index matching, so it has not completely eliminated interference fringes. .

[Problems to be Solved by the Invention] The present invention has been made in order to solve the above-mentioned problems that could not be solved in the prior art. Therefore, the objective is to provide a coating composition that can be suitably used for plastic substrates, especially substrates with a high refractive index, and has good scratch resistance, adhesion, dyeability, heat resistance, and transparency. , a high refractive index coating composition which has excellent other properties and does not produce interference fringes due to interference effects between the surface of a plastic substrate and the coating film, and a coating film made from the coating composition. An object of the present invention is to provide a new plastic molded product formed on the surface of a plastic base material.

[Means for Solving the Problems] That is, the present invention provides a high refractive index coating composition and its high refractive index characterized by comprising the following component (△) or the (A) component and the following (B) component: The object of the present invention is to provide a plastic molded article, characterized in that a coating film made of a polyurethane coating composition is provided on at least one surface of a plastic substrate.

(A) At least one compound having a repeating position 111 represented by the general formula.

(However, in the formula, X and Y are each halogen excluding fluorine,
It represents a methyl group, an ethyl group, or a methoxy group, and a and b each represent an integer of O to 4, which may be the same or different. ) (At least one organosilicon compound represented by the general formula %Bl or a hydrolyzate of the compound.

(However, in the formula, R' and R'' each represent an organic group having 1 to 16 carbon atoms, Z represents a hydrolyzable functional 41 group, and may be the same or different, and c and d each represent O~
In the coating composition of the present invention, component (A) is an indispensable component to obtain a coating film with a high refractive index, and at the same time, the component (A) It is also a useful component for improving the adhesion of.

As the compound in component (A), for example, +S)-
3-C11□C11zsquare)-CIl□011. ÷SHI1 A compound having a repeating unit such as
At least one selected from the following polymers (PC measurement) is used.

The polymer made of the compound shown above can be obtained, for example, by reacting divinylbenzene and p-benzenethiol under ultraviolet irradiation or in the presence of a radical polymerization initiator. (Refer to JP-A No. 62-270627) Component (r3) is selected depending on the scratch resistance, flexibility, drug discovery property, etc. of the coating film made of the coating composition. Since the refractive index is relatively low, it is necessary to consider the balance between the desired refractive index and function. (B)
Specific representative examples of the components include tetraalkoxysilanes such as methyl silicate, ethyl silicate, n-propyl silicate, i-propyl silicate, n-butyl silicate, 5ec-butyl silicate and monobutyl silicate, and hydration thereof. Decomposition products include methyltrimethoxysilane, methyltriethoxysilane, methyltrimethoxyethoxysilane, methyltriacetoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane , vinyltriacetoxysilane, vinyltrimethoxyethoxysilane, phenyltrimethoxysilane 5 phenyltriethoxysilane, phenyltriacetoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropyltriethoxysilane, γ-chloropropyltriacetoxy Silane, 3.3.3-Trifluoropropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ- Mercaptopropyltriethoxysilane, N-β-(aminoethyl)γ-aminopropyltrimethoxysilane, βcyanoethyltriethoxysilane, methyltriphenoxysilane, chloromethyltriethoxysilane, chloromethyltriethoxysilane, glycidoxymethyl Trimethoxysilane, glycidoxymethyltriethoxysilane, a-glycidoxyethyltrimethoxysilane, α-glycidoxyethyltriethoxysilane, β-glycidoxyethyltrimethoxysilane, β-glycidoxyethyltriethoxy Silane, a-
Glycidoxypropyltrimethoxysilane, a-glycidoxypropyltriethoxysilane, β-glycidoxypropyltrimethoxysilane, β-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane Silane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltributoxysilane, γ-glycidoxypropyltributoxysilane, γ
- glycidoxyprobyltrimethoxyethoxysilane,
γ-Glycidoxypropyltrifenoxysilane, a-
Glycidoxybutyltrimethoxysilane, a-glycidoxybutyltriethoxysilane, β-glycidoxybutyltrimethoxysilane, β-glycidoxybutyltriethoxysilane, γ-glycidoxybutyltrimethoxysilane, γ- Glycidoxybutyltriethoxysilane, δ
-glycidoxybutyltrimethoxysilane, δ-glycidoxybutyltriethoxysilane, (3,4-epoxycyclohexyl)methyltrimethoxysilane, (3,4
-Epoxycyclohexyl)methyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, β-(3,4epoxycyclohexyl)ethyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltriethoxysilane Propoxysilane, β-(
3,4-epoxycyclohexyl)ethyltributoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxyethoxysilane, β-(3,4-epoxycyclohexyl)ethyltriphenoxysilane, γ-
(3,4-epoxycyclohexyl)propyltrimethoxysilane, γ-(3,4-epoxycyclohexyl)
Propyltriethoxysilane, δ-(3,4-epoxycyclohexyl)butyltrimethoxysilane, δ-(3
, 4-epoxycyclohexyl) butyltriethoxysilane, trialkoxysilane, triazyloxysilane or trialkoxysilane rI or its hydrolyzate, and dimethyldimethoxysilane, phenylmethyldimethoxysilane, dimethyljethoxysilane, phenylmethyljethoxy Silane, γ-chloropropylmethyldimethoxysilane, γ-chloropropylmethyljethoxysilane, dimethyldiacetoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyljethoxysilane, γ-mercabutobrobilmedyl Dimethoxysilane, γ-mercaptopropylmethyljethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyljethoxysilane, methylvinyldimethoxysilane, methylvinyljethoxysilane, glycidoxymethylmethyldimethoxysilane, glycide xymethylmethyljethoxysilane, a-glycidoxyethylmethyldimethoxysilane, a-glycidoxyethylmethyljethoxysilane, β-glycidoxyethylmethyldimethoxysilane,
β-glycidoxyethylmethyljethoxysilane, a-
Glycidoxypropylmethyldimethoxysilane, a-glycidoxyethylmethyljethoxysilane, β-glycidoxypropylmethyldimethoxysilane, β-glycidoxypropylmethyljethoxysilane, γ-glycidoxypropyl Methyldimethoxysilane, γ-glycidoxypropylmethyljethoxysilane, γ-glycidoxybrobylmethyldibropoxysilane, γ-glycidoxybrobylmethyldibutoxysilane, γ-glycidoxypropylmethyl Dimethoxyethoxysilane, γ-glycidoxypropylmethyldiphenoxysilane, γ-glycidoxypropylethyldimethoxysilane, γ-glycidoxypropylethyljethoxysilane, γ-glycidoxypropylethyldibroboxysilane , γ-glycidoxypropylphenyldimethoxysilane, γ-glycidoxypropylphenyldimethoxysilane, γ-glycidoxypropylphenyldimethoxysilane, γ-glycidoxypropylphenyldiethoxysilane, etc. Examples include alkoxysilanes and diacyloxysilanes, and at least one selected from these compounds is used.

Component (△) gives a coating composition with a high refractive index when used alone, but when used in combination with component (r3),
By changing the ratio of component (A) and component (r3), it is possible to obtain a coating composition with a wide range of refractive index values.

The coating composition of the present invention may contain component (A) alone or (
It is only necessary to mix component A) and component (B) to 111, or to mix them together with additives as described below, which are added as necessary. May be mixed. For partial hydrolysis, use hydrochloric acid,
This is achieved by adding an acidic aqueous solution such as acetic acid or sulfuric acid or pure water.

When component (A) and component (B) are used in combination, it is possible to perform hydrolysis at the same time when mixing them, and in such a case, water etc. may be added at least once, but it is preferable to perform hydrolysis. In order to control the rate, it is desirable to carry out the process while adjusting the liquid temperature and addition rate. Alcohol, alkoxy alcohol, etc. are produced during hydrolysis, but by removing appropriate amounts of these and water under heating and reduced pressure,
The solid content concentration can be adjusted relatively arbitrarily. Further, by adding an appropriate solvent after complete removal, substantially any solvent can be selected. As a solvent, alcohol,
Esters, ethers, ketones, halogenated hydrocarbons, and aromatic solvents can be used depending on the purpose, and if necessary,
Mixed solvent systems are also possible.

Furthermore, there is no problem in adding various additives to this composition depending on the purpose. Various surfactants can be used to improve the smoothness of the coating film obtained with this coating composition. Further, various additives such as various metal oxide sols, epoxy resins, butyral resins, etc. can also be added. In addition, ultraviolet absorbers such as benzophenone type, triazole type, and salicylic acid type can be added to prevent yellowing. These various additives are selected in consideration of their compatibility with the coating composition.

The coating composition of the present invention can be applied to or dipped into a plastic substrate and then heat-treated to form a coating film on the plastic deck. The method for applying or dipping the composition onto plastics is not particularly limited, and conventional methods such as spin coating, spray coating, flow coating, and roller coating may be employed. In addition, the heat treatment was performed at 7
10 to 120 minutes at a temperature of 0 to 200°C is sufficient, and a cured coating film that can withstand practical use is formed. A curing accelerator useful for accelerating curing during heat treatment may be added, such as organic acids and their acid anhydrides, nitrogen-containing organic compounds, various metal complex compounds, or metal alkoxides. Further examples include various salts of alkali metals and alkaline earth metals such as organic carboxylates, carbonates, and perchlorates.

The coating film made of the coating composition of the present invention has high scratch resistance even if it is relatively thin, and if it is thin like the coating film made of conventional coating compositions, hardness cannot be obtained, and if it is thick, the coating film may crack. There is no problem with doing so. Furthermore, increasing the film thickness numerically is disadvantageous in terms of cost. Then,
In the present invention, a sufficient effect can be obtained with a film thickness of 0.05 to 2μ, more preferably 0.08 to 1.2μ.

Examples of the plastic base material in the present invention include acrylic resin, polycarbonate resin, polystyrene, and dielene glycol bisallyl carbonate (hereinafter referred to as CR
-39), Cr? -39 and styrene copolymer, CR-39 and diallyl phthalate polymer copolymer, (halogenated) diallyl carbonate polymer of bisphenol△ and its copolymer, (halogenated)
Preferred examples include di(meth)acrylate polymers of bisphenol A and copolymers thereof, urethane-modified (meth)acrylate polymers of (halogenated) bisphenol, and copolymers thereof. Then,
A transparent plastic base material is particularly preferable, but even if it is opaque, it has the effect of improving the surface reflectance and improving the surface gloss, and it does not matter whether it is transparent or opaque.

Furthermore, the shape of the plastic molded product provided with the coating film is not particularly limited.

[Examples] The present invention will be specifically explained below using Examples, but it goes without saying that the present invention is not limited to these Examples.

Examples 1 to 3 Comparative Example 1 ■ Preparation of coating composition (A) component liquid The following formula Δ-
Repetition represented by 1! 5.0 g of a compound having the i1 position (weight ratio: 40,000) was added to N-methyl-2-
It was dissolved in 100 g of pyrrolidone at 75°C, maintained at 75°C for 5 hours, and then left at room temperature.

(Hereinafter, this solution will be abbreviated as I-1Δ~l.) ■ Preparation of component liquid (B) for coating composition 5 g of γ-glycidoxypropyl trimethoxysilane was
- It was dissolved in 65.8 g of pyrrolidone, and 2.5 g of a 1% aqueous hydrochloric acid solution was gradually added dropwise thereto at 5° C. or lower. The temperature was maintained at 5°C for 2 hours after the completion of the dropwise addition, and then the temperature was returned to room temperature. Furthermore, 0.1 g of magnesium perchlorate was added, and the mixture was aged at room temperature for one week. (Hereinafter, this solution will be abbreviated as 1-(B-1).) ■ Preparation of coating composition and formation of coating film on base material +1Δ-1 and 11B-1 prepared as above are shown in Table I. A liquid coating composition was prepared by mixing in the indicated proportions.
Substrate made of R-39 plate was immersed and pulled at a speed of 9 cm.
The mixture was heated at 170° C. for 30 minutes at a temperature of 100° C. to form a cured coating film. The thickness of this coating film was 0.2μ.

The refractive index of the coating film made of the coating composition of the present invention thus obtained was measured and evaluated by the following test method, and the results are shown in Table 1.

l Abrasion Resistance Test The resistance to scratching by rubbing with #0000 steel wool (trade name: "Bonstar Product") was examined, and the I"11 was determined as follows.

Δ: No scratches even with strong friction B: Slight scratches with strong friction C: Many scratches with strong friction 2 Adhesion test Cross-cut tape test was conducted on the coating surface with a knife I
Cross-cut 100 squares by inserting 11 parallel lines vertically and horizontally at mm intervals, adhere cellophane adhesive tape on top of the cross-cuts, then strongly peel off the tape in a 90° direction.1.
Among the 00 square openings, the number of square openings that did not release 1a++ was investigated.

3 Degree of interference fringes Observe with the naked eye the formation of a rainbow pattern due to light interference when fluorescent light is reflected on the lens surface with a black background.
Judgment was made as follows.

A: Rainbow pattern is not recognized.

B: A slight rainbow pattern is observed.

C: A rainbow pattern is clearly observed.

Table 1 Examples 4 to 6 The compound of 11Δ-1 in Example 2 was expressed as 1111 notation Δ
A coating composition was prepared in the same manner as in Example 2, except that a compound having the 111th repeating position (average weight 11 molecule @ 53,000) represented by the formula Δ-2 below was used in combination with the proportions shown in Table 2. It was adjusted and applied to a substrate to form a coating film. The thickness of this coating film was 0.2μ.

Table 2 shows the evaluation test results for the coating film.

Table 2 Examples 7 to 20 Comparative Examples 2 to 5 ■ Preparation of high refractive index base material 2. 2-bis(4-(2-allyloxycarbonyloxy)ethoxy-3-5 to dibropropylene 1 propane 7
To a mixed composition of m parts of car D, 30 parts by weight of diallyl isophthalate, and 5 parts by weight of benzyl allyl carbonate, 1.5 parts by weight of cisobrobil baroxydicarbonate h as a radical polymerization initiator was added and mixed.

Next, this mixed solution was cast-polymerized using a gasket. Polymerization was started by increasing the temperature from 40°C to 90°C, and then maintained at 90°C for 2 hours.

After the polymerization was completed, the substrate was taken out and annealed at 110° C. for 2 hours.

In this way, a transparent base material with a refractive index of 1.585 was obtained.

■ Preparation Example 1 of component liquid (A) for coating composition
Same as 3.

(2) Preparation of component liquid (B) for coating composition The compound shown in Table 3 was dissolved in N-methyl-2-pyrrolidone, and pure water was gradually added dropwise thereto to prepare the solution.

(hereinafter F, Add this solution to 11 B-2 to IIB-19 It is abbreviated as

Bl = MeSi (OM(ri 3゜ B2 = ELSi (OMe),.

B3=PhSi (OMc) 3゜ 84 = ll5Si (OMel,.

135=,clI□CIICII□0C3116SI
(OEt) 2゜B6” C11a ClIC1lJC
alleSI (OMe) 3.

\1 CI+.

B7 = S i (OMe) 4 ■ Preparation of coating introducer and formation of coating film on base material HA-1 and HB-2 to HB-1-I prepared as above
B-19 in the proportions shown in Table 4 to prepare a liquid coating composition. This solution was applied to the base material of IOcmX lOcmX 2mm prepared in the above ①.
A coating film was formed in the same manner as in 3. The thickness of this coating is 0
．． It was 2μ.

Table 4 shows the evaluation test results for the coating film.

Table Examples 21 to 25 ■ Preparation of coating composition (A) component liquid Same as Examples 1 to 3 except that a compound having a repeating unit represented by the following formula A-3 (weight average molecular weight 71.000) was used. It was prepared in the same way. (Hereinafter, this solution will be abbreviated as 11Δ-co3.) ■Preparation Examples 1 to 3 of Coating Composition (B) Component Liquid
Same as.

■Preparation of coating composition and formation of coating film on substrate" HΔ-3 and l-I B-1 prepared as described in 1 were mixed in the proportions shown in Table 5 to form a liquid coating composition. It was adjusted. The same C as used in Examples 1 to 3 was added to this solution.
A coating film was formed on a substrate made of R-39 board in the same manner as in Examples 1 to 3. The thickness of this coating film was 0.2μ.

Table 5 shows the evaluation test results for the coating film.

Table Examples 26 to 29 ■ Coating composition A compound having a repeating unit represented by the following formula Δ-4 (A) Preparation of component liquid (Δ-4) (・n: average molecular weight iit 88,000) Other than that, Example 1~
It was prepared in the same manner as in 3. (Hereafter, this solution will be referred to as IIΔ-
It is abbreviated as 4. ) ■ Preparation Examples 1 to 3 of coating composition (B) component liquid
Same as.

■Adjustment of coating composition and formation of coating film on base material Feathers A-4 and 11B-1 prepared as above are shown in Table 6.
Mix the liquid coachine in the proportions shown.

Adjusted the silk paraboloid. A coating film was formed on this liquid in the same manner as in Examples 1 to 3 on a substrate made of a CR-39 board similar to that used in Examples 1 to 3. The thickness of this first coat was 0.2 μm.

Table 6 shows the evaluation test results for the coating film.

Table 6 Examples 30-43 Comparative Examples 6-9 ■ Preparation Examples 1-3 of coating composition (A) component liquid
Same as.

(2) Preparation of component liquid for coating composition (r3) The compound shown in Table 7 was dissolved in diacetodialcohol, and pure water was gradually added dropwise thereto to prepare. (Hereinafter, add this solution to 111
Abbreviated as 3-20 to 3-36. ) Table B6= l1ii Same as Table 3, CIl, ClICl
1. OC, 11, si (OMe) 3゜old = Table 3 above
Same as, MeSi (0!1le)s, B2=IIil
Same as Table 3, ELSi fOMel 3°B8=S
i02 sol, B9=SbO, sol, B10=epoxy resin El'-828''1 manufactured by Yuka Shell Co., Ltd.).

■ Preparation of coating composition and formation of coating film on substrate 1- II A-1 and HB-20 prepared as described above
II B-36 in the proportions shown in Table 8 to prepare a liquid coating composition. Example 7~
IOcmxloc with refractive index of 1.585 prepared at 20
A coating film was formed on a base material of m×2 mm in the same manner as in Examples 7 to 20. The thickness of this coating film was 0.2μ.

Table 8 shows the evaluation test results for the coating film.

Table [Effects of the Invention] The high refractive index coating composition of the present invention can be applied to various PlusDeck substrates to form a film,
A film with excellent adhesion, heat resistance, and scratch resistance can be obtained, and these properties are effective even if the film is relatively thin, and even though it provides a film with a high refractive index, it has favorable effects such as interference fringes. It has the excellent feature that there are no phenomena that do not exist.

In particular, it has the effect of being able to obtain coatings with desired refractive index values over a wide range depending on the purpose, making it possible to realize highly functional plastic substrates.

Moreover, the plastic substrate on which the film made of the high refractive index coating composition of the present invention is formed has the effect of enabling a wide range of applications.

Claims (2)

[Claims] (1) The following (A) component or the (A) component and the following (B)
A high refractive index coating composition comprising: (A) At least one compound having a repeating unit represented by the general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
seed. (However, in the formula, X and Y are each halogen excluding fluorine,
It represents a methyl group, an ethyl group, or a methoxy group, and may be the same or different. a and b each represent an integer of 0 to 4. ) (B) General formula R^1_cR^2_dSiZ_4_-_(_c_+_d
At least one type of organosilicon compound represented by __) or a hydrolyzate of the compound. (However, in the formula, R^1 and R^2 each have 1 to 16 carbon atoms.
Z represents a hydrolyzable functional organic group and may be the same or different; c and d are each 0 to 3;
is an integer that satisfies 0≦c+d≦3. ) (2) A plastic molded article, characterized in that a coating film made of the high refractive index coating composition according to claim 1 is provided on at least one surface of a plastic substrate.