JP3090676B2 - Method for producing plastic-coated articles - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a plastic-coated article having excellent surface hardness and durability. More specifically, after performing surface treatment with ultraviolet light on the surface of various molded products,
The present invention relates to a method for producing a coated molded article for forming a silicon-based hard coat.

[Prior art] Plastic articles are widely used in various industrial products and household goods due to their excellent workability. However, they have low surface hardness and low abrasion resistance, which limits their use. It had something. For this reason, various efforts have been made to improve the properties of the surface by treating the surface with various surface treatment agents, and to further improve the performance and expand the range of application. A method of coating with a system-based composition has been proposed. For example, a partial condensate of the formula CH ₃ Si (OH) ₃ , colloidal silica and a water-alcohol solution are coated on the surface of a plastic article in the presence of a condensation catalyst such as an acid. A method of forming a coating is known. (Japanese Patent Publication 52-3969
No. 1, JP-B-56-18624, JP-B-57-2735) [Problems to be Solved by the Invention] However, these silicon-based compositions have poor adhesion to plastics, which are organic base materials. , A method of etching the plastic substrate surface with an aqueous alkali solution,
A method of sanding the surface or a method of applying a primer having excellent adhesion to both surfaces of the plastic base material and the silicon-based hard coat are performed. However, these methods are not only disadvantageous in terms of processing time but also in cost.

On the other hand, a method of irradiating various active energy rays on the surface of a plastic base material to increase the adhesion has been performed. These are performed by ordinary ultraviolet irradiation without specifying a wavelength, corona discharge, plasma treatment, etc., but the ultraviolet irradiation method causes yellowing of the substrate, and there is a problem in productivity in corona discharge or plasma treatment. .

[Means for Solving the Problems] The present inventors have conducted various studies to solve this problem, and by irradiating ultraviolet energy from a specific light source and further performing treatment with an organic solvent or an aqueous alkali solution. It was found that the adhesion, water resistance and weather resistance of the silicon-based hard coat were improved without yellowing of the substrate.

That is, the method for producing a plastic-coated article according to the present invention, when forming a silicon-based hard coat film on the surface of the plastic molded article, 400nm on the plastic surface
A hard coat film is formed by irradiating ultraviolet energy from a light source in which a light amount of 300 nm or less occupies 45% or more of the following ultraviolet light amounts, and further performing a treatment with an organic solvent or an alkaline aqueous solution. .

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

Examples of the plastic substrate used in the present invention include polymethyl methacrylate, polycarbonate, polystyrene, poly 4-methylpentene, polycyclohexyl methacrylate, methyl methacrylate-cyclohexyl methacrylate copolymer, styrene-acrylonitrile copolymer, and methyl methacrylate-styrene copolymer. Polymer, poly (tricyclo ( ^5.2.1.02,6 ) decane-8-yl methacrylate), methyl methacrylate tricyclo ( ^5.2.1.02,6 ) decane-8-yl methacrylate copolymer Transparent thermoplastics such as coalesce, methyl methacrylate-isobornyl methacrylate copolymer, methyl methacrylate-phenyl methacrylate copolymer, urethane (meth) acrylate, epoxy (meth) acrylate, Copolymers of a monoester or polyfunctional (meth) acrylate with a ester (meth) acrylate or the like, transparent thermosetting plastics such as poly (diethylene glycol bisallyl carbonate), and the like.

These plastic molded articles or those obtained by coating the surface thereof with an organic hard coat comprising a polyfunctional (meth) acrylate can also be used as the substrate of the present invention.

Next, the silicon-based hard coat film to be coated on the plastic substrate is a high-hardness film made of a compound having at least a Si-O-Si bond and three-dimensionally crosslinked. In particular, a coating obtained from an organosilicon compound represented by the following general formula (I) and / or a hydrolyzate thereof is preferable.

R ¹ _a R ² _b SiX _4-ab (I) (wherein R ¹ and R ² are each alkyl, alkenyl, aryl,
A hydrocarbon group having at least one substituent selected from halogen, epoxy, glycidoxy, amino, mercapto, methacryloxy and cyano groups, X is a hydrolyzable group, and a and b are 0 or 1. Representative examples of the compound represented by the general formula (I) include methyl silicate, ethyl silicate, methyl triethoxy silane, ethyl triethoxy silane, vinyl triethoxy silane, phenyl triethoxy silane, and γ-methacryloxypropyl trimethoxy silane. Γ-aminopropyltriethoxysilane, glycidoxymethyltrimethoxysilane, glycidoxytriethoxysilane, α-glycidoxyethyltriethoxysilane, β-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltri Examples are dialkoxysilanes or diacyloxysilanes such as ethoxysilane, γ-glycidoxypropyltrimethoxysilane, and hydrolysates thereof. One or more of these organosilicon compounds can be added.

These organosilicon compounds are preferably used after being hydrolyzed in order to lower the curing temperature and accelerate the curing.

The hydrolysis is produced by adding pure water or an acidic aqueous solution such as hydrochloric acid, acetic acid or sulfuric acid, followed by stirring.
Further, the degree of hydrolysis can be easily controlled by adjusting the amount of pure water or acidic aqueous solution. In the hydrolysis, X of the general formula (I)
The addition of pure water or an acidic aqueous solution in an amount equal to or greater than the molar amount of the group and not more than 3 times the molar amount is particularly preferred in terms of accelerating curing.

As a curing agent, various epoxy resin curing agents, or various organic silicon resin curing agents, various organic acids and their acid anhydrides, nitrogen-containing organic compounds, various metal compounds or metal alkoxides, and alkali metal organic carboxylate, carbonate Various salts such as salts are included. These curing agents can be used as a mixture of two or more kinds.

The silicon-based hard coat film is obtained by curing the above-mentioned coating composition, and the curing is usually performed by heat treatment. Alternatively, ultraviolet rays, electron beams, or the like may be used. In addition, a sufficiently good result is obtained at a temperature of 50 to 250 ° C. in the case of the heat treatment.

On the other hand, as a means of applying the silicon-based hard coat film, brush coating, dip coating, roll coating, spray coating,
Conventional coating methods such as spin coating and flow coating can be easily used.

Further, various compounds can be added to the hard coat film of the present invention for the purpose of improving weather resistance and hardness. Specific examples of such additives that can be added include various epoxy resins,
There are various ultraviolet absorbers such as acrylic resin, polyvinyl alcohol, and cellulose polymer. Further, inorganic oxide fine particles other than antimony oxide such as zircon oxide and titanium oxide, among which sols dispersed in various dispersion media from the viewpoint of compatibility and transparency are preferably used.
In practicing the present invention, ultraviolet energy having a wavelength of 180 nm to 300 nm is applied to the surface of the aforementioned transparent plastic substrate.
Irradiation of 300 mJ / cm ² or more, and further immersion in an organic solvent or an alkaline aqueous solution (for example, a sodium hydroxide aqueous solution having a concentration of 0.1 to 20% by weight) at room temperature to 50 ° C. for 5 to 120 minutes, followed by washing,
Dry and apply a silicon hard coat.

When irradiating the above-mentioned ultraviolet energy, 400 nm
It is preferable to use a light source in which a light amount of 300 nm or less accounts for 45% or more of the following ultraviolet light amounts. If a light source having a large amount of light of 300 nm or more, such as a high-pressure mercury lamp or a metal halide lamp, is used, although the adhesion of the silicon-based hard coat can be obtained, the plastic substrate is undesirably yellowed.

In the present invention, the adhesion of the silicon-based hard coat can be obtained only by surface treatment by irradiation with ultraviolet energy, but in order to obtain long-term durability and water resistance, the organic solvent or water after irradiation with ultraviolet energy as described above is used. It is effective to combine an alkali treatment such as an aqueous sodium oxide solution.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples.
The following light sources were used for ultraviolet energy irradiation. The wavelength distribution of the energy intensity of these light sources is shown in FIGS. (Octsuka Electronics Co., Ltd., Instant Multiphotometer MCPD-10
(A) Measured by 00) (A) Of the ultraviolet light quantity of 400 nm or less, 45
% Mercury lamp (Fig. 1) (B) High pressure mercury lamp (Fig. 2) (C) Metal halide lamp (Fig. 3) Comparative Example 8 (1) Surface treatment Acrylic plate (PMMA; manufactured by Mitsubishi Rayon Co., Ltd.) ,Product name
Acrylite L, 10cm x 10cm x 3mm) 15c from both sides of the board
Ultraviolet energy of 2000 mJ / cm ² (measured at a center wavelength of 250 nm) was irradiated by a light source (A) placed at a distance of m.

(2) Application and curing of hard coat Next, a silicon hard coat liquid (Toshiba Silicon Co., Ltd.)
The product was coated by the dipping method under the trade name of Tosguard 510). The lifting speed was 10 cm / min.
This was cured by heating at 85 ° C. for 4 hours. The thickness of the cured film thus obtained is about 2.5 microns, the hardness,
Both gloss and appearance were excellent.

(3) Test and evaluation results The hard coat film obtained in Comparative Example 8 was evaluated by the following method. Table 1 shows the obtained results.

(A) Initial adhesion of hard coat: A cross-cut cellophane tape peeling test was performed in accordance with JISD-0202. (Cross cut makes 100 1mm squares,
It was indicated by the number of squares remaining after three times of the cellophane peel test. (B) Yellowing of the substrate; Yellowing of the substrate after irradiation with ultraviolet energy was visually evaluated.

；: No change Δ: Slightly yellowing ×: Extremely yellowing (c) Water resistance: Changes in appearance and adhesion after immersion in hot water at 60 ° C for 3 days were evaluated.

；: No change Δ: partial change ×: overall change (d) Weather resistance: Adhesion after exposure for 500 hours in a sunshine weather meter was evaluated.

○: no change △: partial release ×: full release Example 1 In Comparative Example 8, an organic hard coat treated plate (trade name: Acrylite MR; manufactured by Mitsubishi Rayon Co., Ltd .; 10 cm × 10 cm) was used instead of the acrylic plate as the base material. Irradiate the surface with ultraviolet energy of 2000 mJ / cm ² from the light source (A) using a light source (A), immerse it in a 10% by weight aqueous sodium hydroxide solution at room temperature for 2 hours, wash with water, dry, and then 0.05% by weight aqueous sulfuric acid It was immersed in the solution at room temperature for 1 minute, washed with water and dried. The application and curing of the hard coat were performed in the same manner as in Comparative Example 8. Table 1 shows the results
It was also described in.

Example 2, Comparative Examples 1 to 7 A hard coat film was formed and evaluated according to the method of Comparative Example 8 and Example 1. The abbreviations in Table 1 are shown below.

PC; polycarbonate plate (Mitsubishi Gas Chemical Co., Ltd., trade name; Iupilon ML-300 10 cm × 10 cm × 3 mm) CR-39; poly (diethylene glycol bisallyl carbonate) (flat plate; 10 cm × 10 cm × 3 mm, diethylene glycol bisallyl carbonate) 3 parts of diisopropyl peroxypercarbonate was mixed with 100 parts, and cast polymerization was performed using a glass mold.) [Effects of the Invention] As described above, the method for producing a plastic-coated article of the present invention provides a method for forming a silicon-based hard coat film on the surface of a plastic molded article by applying 40% to the surface of the plastic.
In this method, ultraviolet energy is irradiated from a light source in which the light amount of 300 nm or less occupies 45% or more of the light amount of 0 nm or less, and the treatment is performed with an organic solvent or an alkaline aqueous solution. This ultraviolet irradiation activates the surface and strongly bonds the film and the substrate without causing yellowing of the substrate, so that it exhibits excellent adhesion, and the treatment with an organic solvent or an alkaline aqueous solution has excellent water resistance. And weather resistance.

[Brief description of the drawings]

FIG. 1 is a diagram showing a wavelength distribution of a light source used in the embodiment,
2 and 3 are diagrams showing the wavelength distribution of the light source used in the comparative example.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-1-267609 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J ^7/ 00-7/18

Claims (1)

(57) [Claims] (1) When forming a silicon-based hard coat film on the surface of a plastic substrate, 40
Plastic coating characterized by irradiating ultraviolet energy from a light source in which the light amount of 300 nm or less occupies 45% or more of the ultraviolet light amount of 0 nm or less, further treating with an organic solvent or an alkaline aqueous solution, and then forming a hard coat film Article manufacturing method.