JPS5989330A - Surface coating of molded plastic article - Google Patents

Abstract

PURPOSE:To apply a coating film having excellent surface hardness and high durability and adhesivity to the surface of a plastic molded article, in high productivity, by coating the surface with a specific composition, and curing the film by actinic energy radiation. CONSTITUTION:The surface of a plastic molded article is coated with a composition composed of (A) powdery silicon oxide, (B) one or more (meth)acrylate oligomer having (meth)acryloyl group in the molecule and/or (C) a mixture of a polyfunctional allyl or allylidene compound (e.g. diallyl phthalate) and a polyfunctional thiol (e.g. ethylene dithioglycol), (D) a polyfunctional (meth)acrylic monomer (e.g. ethylene glycol diacrylate) and if necessary, (E) a photosensitizer (e.g. benzophenone), and the coating film is cured by the irradiation of actinic energy radiation (e.g. ultraviolet ray, X-ray, etc.) to effect the surface-coating of the plastic molded article.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plastic molding method, which is characterized in that a specific composition is applied to the surface of a plastic molded product, and then active energy rays are irradiated to form a cured coating film on the surface. The present invention relates to a method of coating a plastic molded product, and provides a surface treatment method for improving the surface strength of a plastic molded product by making the surface of a plastic molded product excellent in surface hardness and durability.

Plastics generally have lower surface hardness than metals, glass, and ceramics, and have the disadvantage that their surfaces are easily scratched during storage, transportation, and use.

For this reason, the surface of the molded product is often coated with a hard coat to increase the surface hardness and make it less susceptible to scratches.

Two methods are conventionally used for hard coating plastic molded products.

One method is to apply a substance that forms a hard coating onto the surface of the molded product and cure it on the spot.

A typical example is silicone coating, in which a solution or emulsion of silanol or the like is applied to the surface of the molded product, the solvent is evaporated, and the coating is heated and condensed on the spot to form a silicone coating on the surface. It's a method. This method has the disadvantage that the surface hardness of the coating film obtained is still insufficient, and the adhesion between the plastic and the coating film is weak, and primer treatment is required to improve this. Another method is to form a film of an inorganic material such as aluminum oxide or silicon oxide on the surface of a plastic molded product by vapor deposition. However, this method has drawbacks such as poor productivity and high cost, and also requires a top coat because the adhesion between the deposited film and the plastic is still insufficient.

The present invention has been completed by thoroughly studying the above-mentioned conventional techniques and discovering a highly productive coating method that provides a coating film with high hardness, durability, and excellent adhesion. be.

That is, the present invention provides (1) on the surface of a plastic molded product.
Fine powder silicon oxide (2) Contains an acryloyl group or methacryloyl group in the molecule. at least one (meth)acrylate oligomer, and/or (3) a blend of a polyfunctional allyl or allylidene compound and a polyfunctional thiol, (4) a polyfunctional acrylic or methacrylic monomer, (
5) This relates to a coating method characterized by coating a composition formed by mixing the following and optionally a photosensitizer, and curing the composition by irradiating it with active energy rays.

The characteristics of the present invention are the above components (1) and (2).
) and/or (3), and (4) have good adhesion to plastic molded products, and not only are they excellent in durability, but also have high hardness when cured. Moreover, since the composition has good fluidity, it is suitable for coating plastic molded articles using various coating methods.

Furthermore, since the fine powder silicon oxide of component (1) is well dispersed in the mixture of components (2) and/or (3) and (4), which are resin components, the stability of the coating liquid is good.
Further, the curing time is sufficiently short, from 1 second to 10 minutes, and a protective coating film having excellent characteristics as described above can be obtained.

The reason why the polyfunctional acrylic or methacrylic monomer component (4) is blended with the oligomer component (2) and/or the monomer component (3) in the present invention is as follows. Generally, polymers obtained by curing oligomer component (2) and monomer component (3) have excellent adhesion to plastics, but lack hardness.

On the other hand, polyfunctional acrylic or methacrylic monomer = (4)
The polymer obtained by curing has excellent hardness, but is brittle and has insufficient adhesion. Polyfunctional monomer (4) in oligomer component (2) and/or monomer component (3)
By using them together, the characteristics of both will be brought out even more.

Furthermore, the fine powder silicon oxide of component (1) is a resin component, oligomer component (2) and/or monomer component (3).
Since it is well dispersed in the mixture of monomer component (4) and monomer component (4), the coating liquid has excellent stability. Curing time is 1
It hardens sufficiently in a short time of seconds to 10 minutes. The hardening composition according to the present invention contains silicon oxide, so it has high hardness, and the resin liquid component contains a 7-mer component ((4)).
component) to give a cured product with a high degree of crosslinking, resulting in a cured coating film with excellent hardness and adhesion. Further, since a sufficiently cured protective film can be formed by irradiation with active energy rays for a short period of time as described above, productivity is extremely high. Incidentally, the conventionally used silicon coating method requires a baking operation at 100° C. for 116 hours.

The fine powder silicon oxide used in the present invention as component (1) is used in the form of fine particles having a particle size of several tens to several hundred angstroms. These silicon oxide fine particles may be surface-treated with a silane coupling agent or the like so that they can be easily dispersed in an organic liquid. A commercially available product (organosilica sol) dispersed in an organic liquid can be used.

The finely divided silicon oxide is used by being added and mixed into a mixture of the oligomer component (2) and/or the monomer component (3), and the monomer component (4) and dispersed therein.

The (meth)acrylate oligomer having an acryloyl group or methacryloyl group in the molecule used for component (2) is a compound having two or more epoxy end groups in the molecule (e.g., epichlorohydrin/bisphenol A feed compound, molecular weight 340- Epoxy (meth)acrylate obtained by reacting 2000) with acrylic acid or methacrylic acid, a polyester oligomer with a molecular weight of 20()-3000 having a carboxyl group or hydroxyl group at the end, acrylic acid, methacrylic acid, acrylic acid chloride, methacrylic acid chloride, Polyester (meth)acrylate esterified with hydroxyalkyl acrylate or hydroxyalkyl methacrylate, polyether obtained by esterifying a polyether oligomer with a molecular weight of 200 to 3000 with a hydroxyl group at the end with acrylic acid, methacrylic acid, acrylic acid chloride, or methacrylic acid chloride. (Meth)acrylate, urethane (meth) made by esterifying a urethane oligomer with a molecular weight of 200-3090 with a carboxyl group or hydroxyl group at the end with acrylic acid, methacrylic acid, acrylic acid chloride, methacrylic acid chloride, hydroxyalkyl acrylate or hydroxyalkyl methacrylate Examples include acrylate, diarylidenepentaerythritol (meth)acrylate obtained by reacting diarylidenepentaerythritol with hydroxyalkyl acrylate or hydroxyalkyl methacrylate, and the like. These may be used alone or in combination of two or more.

By changing the reaction conditions (for example, molar ratio and reaction rate), the above component (2) can be obtained with a (meth)acryloyl group at one end as the main component, or with a (meth)acryloyl group at both ends. In the present invention, those having an average of 1.5, preferably 2 or more (meth)acryloyl groups in one molecule are preferred.

Polyfunctional allyl or aIJ as the third component
As for the compounding ratio of the compound of the DEN compound and the polyfunctional thiol, an equivalent ratio of 05 to 20 is preferably used.

This mixture may be used by mixing both components in the above ratio and then mixing the seven-mer component (4) therewith.

Examples of polyfunctional allyl or allylidene compounds include diallyl phthalate, diallyl adipate, diallyl succinate, triallyl in cyanurate, and diallylidene pentaerythritol. Examples of polyfunctional thioyl compounds include ethylene dithioglycol and tri- Examples include thioglycerin, ethylene glycol dithioglycolate, trimethylolpropane trithioglycolate, pentaerythritol trithiopropionate, and pentaerythritol tetrathioglycolate.

Examples of the polyfunctional acrylic or methacrylic monomer that is component (4) include ethylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol diacrylate, propylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, and dipropylene. Glycol diacrylate, diethylene glycol diacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, polypropylene glycol diacrylate, polypropylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, Examples include pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, dipentaerythritol triacrylate, dipentaerythritol trimethacrylate, and the like.

As the photosensitizer which is the fifth component, benzophenone, benzyl, benzoin, dimethoxyacetophenone,
Examples include benzoin methyl ether, benzoin isopropyl ether, thioxanthone, methyl orthobenzyl benzoate, and azobisalkylonitrile.

In the present invention, these photosensitizers are preferably used especially when ultraviolet rays are used in order to promote photopolymerization, but when other active energy rays are used, they can be used without using them. It does not need to be used as it can advance the polymerization.

The blending ratio of these components in the present invention is such that the finely powdered silicon oxide (component (1)) may be used in an amount of 1 to 60 parts by weight based on 100 parts by weight of the total composition, and the amount of component (1) is less than this. Sometimes the hardness of the obtained coating film is insufficient, and when the hardness is higher than this, the adhesion becomes poor.

The photosensitizer, which is the fifth component, is used during ultraviolet curing.
parts by weight are added.

Next-2 As the resin component used in the present invention, the polyfunctional acrylic or methacrylic monomer, which is the (4) component important for improving the hardness of the resulting coating film, and other resin components (2)
, (3) or 1 part by weight of a mixture thereof
0 to 400 parts by weight are used. If the amount of component (4) is less than this, the resulting coating film will have insufficient hardness, and if more than this amount is used, the resulting coating film will become brittle and have insufficient adhesion.

There is no limit to the blending ratio of the (2) component and the (3) component,
Each may be used 100% or in an appropriate blending ratio.

As other components to be added to the composition used in the present invention, a solvent can be used to lower the viscosity of the coating liquid so that it can be applied thinly. As a solvent, methanol, ethanol,
Improper tool, acetone, ethyl acetate, etc. are used. In addition, commonly used additives such as dyes, pigments, ultraviolet absorbers, leveling agents, and antistatic agents can be used.

The composition according to the present invention obtained as described above can be applied to plastic molded products using any of the conventional coach-rreg methods such as roller coating, flow coach ink, dipping, brushing, spray coating, etc. Can be coated on the surface. Generally, after coating, the coating is cured by irradiation with active energy rays, but when the curing composition contains a solvent, the solvent is evaporated by ventilation etc. and then the coating is cured by irradiation with active energy rays.

The thickness of the coating is generally 1 to 50 microns.

Further, depending on the case, a coating may be applied on top of a brimer.

The active energy rays used in the present invention include ultraviolet rays, X-rays, gamma rays, electron beams, etc., and the appropriate irradiation time is 1 second to 10 minutes. After irradiation, after-curing may be performed by heating to 150° C. or lower to remove strain or to complete polymerization.

The coating film obtained by the method of the present invention has good adhesion to the surface of a plastic molded product, as is clear from the following examples.
It has medium hardness and forms a highly durable protective film.

For example, the hardness is 2H or more in pencil hardness, the adhesion is 100/100° in the goblin test, and the durability is unchanged in the weather-o-meter test for more than 5 C'O hours, showing excellent results.

Plastic molding resins used in the method of the present invention include polystyrene, ABS resin, polyester, polysulfone, phenoxy, polyamide, nitrocellulose, acetylcellulose, acetylbutylcellulose, epoxy resin, Subilak resin, urethane resin, diethylene glycol bisallyl carbonate, etc. I can list them.

In addition, the molded products used include extrusion or calendar molded products such as films, sheets, ronds, and pipes, cast products such as lenses, and so-called molded products or laminate products formed by injection molding, blow molding, vacuum forming, etc. It can be used for any molded product to improve its surface properties. The coating film of the present invention is transparent, and does not impair its transparency when the substrate is transparent, and does not impair the color or gloss of the substrate even when the substrate is opaque. .

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 A polystyrene film was uniformly coated with the following composition to a thickness of 7 microns by roller coating.

Particle size: 70 fine powder silicon oxide (component (1)) 3
0 parts by weight Epoxy acrylate (Showa polymer source: Lipoxy 5P1509, Acryloy (component (2)
) 50 parts by weight Contains 2 tetra groups in 1 molecule) Pentaerythritol triacrylate (Component (4)
) 190 parts by weight benzoin methyl ether (component (5)) o6 is fluorine leveling agent
After coating with 0.05 parts by weight, it was completely cured by irradiating ultraviolet rays for 4 seconds with a 6KW high pressure mercury lamp.

This film has improved surface hardness as shown below, and is a polystyrene film that has been subjected to the conventional hard coating method (after being coated with methylphenylsilanol,
The hardness, adhesion, and durability were superior to those obtained by baking for 16 hours.

Hardness Adhesion Durability Sample before processing H-- Example sample 4 H100/100 1000 hour example Example 2 Combination of 1 equivalent of diarylidene pentaerythritol, 1 equivalent of trimethylolpropane trithioglycolate, and 2 equivalents of pentaerythritol triacrylate After immersing Gespirak eyeglass lenses manufactured by UV-curing the material in a resin bath with the following composition and pulling them out, warm air is flowed to evaporate the solvent and form a coating film with a thickness of 5 microns on the lenses. This was irradiated with a 4KW high-pressure mercury lamp for 5 seconds to form a cured coating film.

100 parts by weight of an impropatul dispersion (30%) of finely powdered silicon oxide smoke component (1) with a particle size of 50X 20 parts by weight of diarylidenepentaerythritol (component (3)) h-ik-rh5 (component (3)) 21 parts by weight thioglycolate trimethylolpropane triacrylate (component (4)
) 80 parts by weight benzoin propyl ether
(Component (5)) 0.7 parts by weight This lens has improved surface hardness compared to before treatment, and is a lens that has been coated with methylphenylsilanol and then baked at 100°C for 16 hours. )
It had superior hardness, adhesion, and durability.

Hardness Adhesion Durability (Pencil hardness The composition of 1
The coating was roller coated at a rate of 0.00 m/min to a thickness of 4 microns and then coated with ES11 in a nitrogen stream.
8 inch electrocarte vine.

Finely powdered silicon oxide (component (1)) with a particle size of 100> in the curable composition
50 parts by weight polyester acrylate (component (2))
45 parts by weight 1-dimethylolpropane triacrylate (
Component (4)) 1 ao parts by weight of propylene glycol, adipic acid 4. Glycerin: 1.1: 0
．． It is made by acrylating the terminals of a polyester oligomer with a molecular weight of 980 produced by reacting at an equivalent ratio of 0.05 to 0.05, and contains an average of 2.5 acryloyl groups in one molecule.

This film has improved surface hardness, compared to polyethylene terephthalate film (coated with methylphenylsilanol and baked at 100°C for 16 hours) that has been subjected to the conventional hard coating method.
Both hardness and adhesion were excellent.

Hardness Adhesion Durability Sample before processing HB - Example (5) Sample 3 H100/100 1000
Time Passing Example 4 A plastic lens manufactured by polymerizing diethylene glycol bisallyl carbonate was immersed in a resin bath with the following composition, pulled up, the solvent was evaporated, and the coating was applied to a thickness of 5 microns. Electro curtain (E S I 18 Inch E
electrocurtain) C, irradiated with accelerated electrons through energy. The coating film was completely cured after about 1 second of irradiation.

Formulation of curable composition Pentaerythritol triacrylate (component (4))
50 parts by weight Lenses subjected to this hardening treatment had improved surface hardness as described below, and had superior adhesion compared to lenses subjected to the conventional hard coating method (silicon oxide vapor deposition coating method).

Hardness Adhesion Durability (hard brush hardness 5 A polystyrene film was uniformly coated with the following composition to a thickness of 4 microns using a roller coating method.

Dispersion Diarylidene Bentaeryth 1 Tan-L (Component (3)
) 50 parts by weight Trimethylolpropane triacrylate (Component (4)) 120 parts by weight Benzoin isopropyl ether (Component (5)) 0.5fi
After arriving at the Okibe coach, we used a 4KW high-pressure mercury lamp to absorb 2 ultraviolet rays.
It was completely cured after irradiation for 0 seconds.

This film has improved surface hardness as shown below, and is made of polystyrene film (
10 after coating with methylphenylsilanol
The hardness, adhesion, and durability were superior to those obtained by baking at 0° C. for 16 hours.

Hardness Adhesion Durability j'>7i (>tsu'za) (2) Brush hardness test Denko Co., Ltd. Showa Kobunshi Co., Ltd. Representative Patent Attorney Sei Kikuchi

Claims (1)

[Claims] On the surface of the plastic molded article, (1) finely powdered silicon oxide; (2) at least one type of (meth)acrylate oligomer containing an acryloyl group or a methacryloyl group in the molecule; and/or (3) a blend of a polyfunctional allyl or adenoid compound and a polyfunctional thiol, (4) a polyfunctional acrylic or methacrylic monomer, (5
) A coating method characterized by applying a composition formed by mixing a photosensitizer, as the case may be, and curing the composition by irradiating it with active energy rays.