JPH0687129A - Manufacture of synthetic resin molded article with scratch-resistant film - Google Patents

Abstract

PURPOSE:To provide a manufacturing method, in which the adhesion of film is favorable and which has high productivity, in manufacturing of a synthetic resin molded article with scratch-resistant film. CONSTITUTION:After scratch-resistant film is formed in advance on the inner surface of a mold by applying ultraviolet-curing resin mainly made of urethane acrylate on the inner surface of the mold and cured the resin through the irradiation of ultraviolet light in air atmosphere, synthetic resin stock liquid consisting of ethylene-based unsaturated monofunctional monomer, ethylene-based unsaturated multifunctional monomer and radical polymerization initiator is poured in the mold for performing polymerization.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a synthetic resin molded article having a scratch resistant coating. [0002] Many synthetic resin moldings are currently on the market, and although they have many excellent properties, they generally do not have sufficient scratch resistance. Therefore, there are various methods for improving the scratch resistance of these synthetic resin molded products, but generally, a method of directly coating the surface of the synthetic resin with a resin film having good scratch resistance is known. In addition, Japanese Patent Publication No. 54-14617 and Japanese Patent Publication Sho
In 54-14618, a film-forming raw material composed of a cross-linking polymerizable compound containing a (meth) acryloyloxy group and an ether bond, a thioether bond, an ester bond, an amide bond, a urethane bond, etc. is applied to a template to bring the film into close contact. Or an inert gas atmosphere, that is, by blocking oxygen to perform the initial curing of the film, after that it is post-cured without blocking oxygen, and then has a wear-resistant surface that is polymerized by injecting the base resin material. A method for manufacturing a synthetic resin molded article is described. Further, in JP-A 1-238911, after heating and drying the polysiloxane-based film-forming raw material applied to the mold,
A scratch-resistant methacrylic resin molded article obtained by injecting and polymerizing a base resin raw material containing an alkyl methacrylate as a main component and a cross-linking agent is described. In the method of directly coating the surface of the synthetic resin molded article with the scratch resistant coating, the adhesion between the synthetic resin molded article and the scratch resistant coating is not sufficient. Further, in the methods disclosed in JP-B-54-14617 and JP-B-54-14618, the process is complicated because oxygen is blocked when the film is cured, and the productivity is low. Furthermore, JP-A-1-
In the method disclosed in Japanese Patent No. 238911, it takes a long time to heat and dry the film, and the productivity is low as well. Therefore, even if the synthetic resin molded article is a cross-linked polymer, it provides a method for producing a synthetic resin molded article having a scratch-resistant coating having good adhesion with a scratch-resistant coating and high productivity. To do. SUMMARY OF THE INVENTION The present invention has the following features:
An ultraviolet curable liquid containing urethane acrylate as a main component is applied, and an ultraviolet ray is irradiated in an air atmosphere for curing to form a scratch-resistant film on the inner surface of the mold in advance. A method for producing a synthetic resin molded article with a scratch resistant film, which comprises injecting a synthetic resin raw material liquid comprising a saturated monofunctional monomer, an ethylenically unsaturated polyfunctional monomer and a radical polymerizable initiator, and polymerizing. The mold used in the present invention has an inner shape which is the shape of a desired molded article. For example, if the molded product is plate-shaped, a cell composed of two opposed plates and a gasket can be mentioned. The mold material is, for example, inorganic glass,
Stainless steel, nickel chrome plated metal, aluminum, etc. The UV-curable liquid containing urethane acrylate as a main component used in the present invention is obtained by reacting a polyisocyanate compound and an acrylic monomer having active hydrogen or both with a polyhydric alcohol by a conventional method. It comprises a mixture of urethane acrylate and optionally a copolymerizable monomer, a diluting solvent and a known photopolymerization initiator. As the polyisocyanate compound, for example, an aromatic isocyanate, tolylene diisocyanate,
As xylylene diisocyanate, diphenylmethane diisocyanate, and aliphatic and alicyclic isocyanates, there are diisocyanate compounds such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, methylenebis (4-cyclohexyl isocyanate), and further triphenylmethane triisocyanate. Triisocyanate compounds such as isocyanate and dimethylenetriphenyltriisocyanate; isocyanurates and biurets of the diisocyanate compounds; and polyisocyanate compounds obtained by multimerizing the diisocyanate compounds. Among them, a polyisocyanate compound having three or more isocyanate groups in one molecule, and further an isocyanurate body or a biuret body of the diisocyanate compound are particularly preferable. These may be used alone or in combination of two or more. As the acrylic monomer having active hydrogen, (meth) acrylamides such as N-methylol (meth) acrylamide and N-hydroxy (meth) acrylamide; 2-hydroxyethyl (meth) acrylate,
2-hydroxypropyl (meth) acrylate, 2-hydroxy-3-methoxypropyl (meth) acrylate, trimethylolpropane di (meth) acrylate,
Ditrimethylolpropane tri (meth) acrylate,
Glycerin di (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate and other (meth) acrylates having a hydroxyl group. Is mentioned. Among them, polyfunctional (meth) acrylates having at least one hydroxyl group and at least two (meth) acryloyloxy groups in one molecule are preferable. These may be used alone or in combination of two or more. As the polyhydric alcohol, ethylene glycol, diethylene glycol, propylene glycol,
Dipropylene glycol, 1,4-butanediol,
Polypentaerythritol such as 1,6-hexanediol, glycerin, trimethylolpropane, ditrimethylolpropane, neopentyl glycol, spiroglycol, 2-methyl-2-butyl-1,3-propanediol, pentaerythritol and dipentaerythritol. And so on. Of these, glycerin, trimethylolpropane, ditrimethylolpropane, pentaerythritol, and polypentaerythritol are preferable. These may be used alone or in combination of two or more. The ratio of the acrylic monomer having active hydrogen to the polyhydric alcohol is preferably 0.05 to 0.5 mol, more preferably 0.1 to 0.2, with respect to 1 mol of the former. When the latter is too far away from 0.05 to 0.5 mol, curability and physical properties of the cured product deteriorate. The reaction between the polyisocyanate compound and the acrylic monomer having active hydrogen and / or the polyhydric alcohol may be carried out either before or at the same time as the acrylic monomer having active hydrogen and the polyhydric alcohol which react with the polyisocyanate compound. Good. The ratio of these is such that the total of active hydrogen and hydroxyl groups is 0.9 to 1.8 equivalents, preferably 1 to 1.3 equivalents per equivalent of isocyanate groups of the polyisocyanate compound. Among the urethane acrylates, a polybranched urethane acrylate derived from a polyisocyanate compound having three or more isocyanate groups in one molecule is preferable because it has good curability. Furthermore, a polyisocyanate compound having three or more isocyanate groups in one molecule, a hyperbranched urethane acrylate obtained by reacting an acrylic monomer having active hydrogen, and a polyhydric alcohol are particularly preferable because they have extremely good adhesion. As the copolymerizable monomers, the above-mentioned acrylic monomers having active hydrogen and various (meth) acrylates are suitable. As the photopolymerization initiator, a cleavage type polymerization initiator such as benzoin, benzoin ethers, 1-hydroxycyclohexyl phenyl ketone, benzyl dimethyl ketal, acylphosphine oxide, etc .; It is a polymerization initiator or the like. If necessary, a photosensitizer may be used in combination. The photopolymerization initiator is used in an amount of 0.1 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of urethane acrylate. Examples of the method of applying the ultraviolet curable liquid to the mold include spin coating, bar coating, roll coating, spray coating, and brush coating. The thickness of the coating film of the ultraviolet curable liquid depends on the wall thickness of the synthetic resin molded product, but is preferably about 3 to 50 μm from the viewpoint of the balance between scratch resistance and mechanical strength. The ultraviolet ray irradiation of the present invention may be a general ultraviolet ray irradiation machine such as a high pressure mercury lamp, a metal halide lamp, a low wavelength UV lamp, a xenon lamp, a crypto arc lamp, a xenon flash lamp or a flash UV lamp, and is particularly limited. Not done. Irradiation with ultraviolet rays may be carried out to such an extent that the surface of the ultraviolet curable liquid coating film becomes tack-free, and it is not necessary to completely cure it. The amount of UV irradiation is generally 100-
It is about 5000 mJ / cm ² . Specifically, this is determined by the intensity of the light source used, the thickness of the coating film, the type and concentration of the photopolymerization initiator, etc., so that suitable conditions can be set by several trials. The raw material liquid of the present invention comprises an ethylenically unsaturated monofunctional monomer, an ethylenically unsaturated polyfunctional monomer and a radical polymerization initiator. Further, a polymer soluble in the monomers is dissolved. So-called syrup may be used. Examples of the ethylenically unsaturated monofunctional monomer of the present invention include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isopropyl (meth) acrylate, and (meth) acrylic. (Meth) acrylic acid esters of aliphatic alcohols and alicyclic alcohols having 1 to 25 carbon atoms such as bornyl acid ester, cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate; aromatic vinyl such as styrene Compounds; vinyl esters such as vinyl acetate; and the like. Among them, monomers mainly composed of methyl methacrylate and styrene are common in view of easy availability, polymerization curability, transparency of the polymer, and strength. As the ethylenically unsaturated polyfunctional monomer,
Ethylene glycols such as ethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, or oligomers thereof having both terminal hydroxyl groups esterified with (meth) acrylic acid; neopentyl glycol di (meth) acrylate, Hydroxyl groups of other dihydric alcohols such as hexanediol di (meth) acrylate esterified with (meth) acrylic acid; bisphenol A or alkylene oxide adducts of bisphenol A , Those esterified with (meth) acrylic acid; those obtained by esterifying polyhydric alcohols such as trimethylolpropane and pentaerythritol with (meth) acrylic acid; and glycidyl of the above dihydric alcohols or polyhydric alcohols (meth ) Acry Those were the glycidyl group of esters by ring-opening addition; allyl (meth) acrylate, diallyl phthalate, diallyl maleate, divinyl benzene and the like. The polyfunctional monomer has a mechanical strength of a molded article,
Improves heat resistance. For these, 0.1 to 30% by weight in the raw material liquid is necessary. Examples of the radical polymerization initiator include diacyl peroxides such as benzoyl peroxide, lauroyl peroxide and disuccinic acid peroxide; di-t-butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide and the like. Dialkyl peroxides; peroxyesters such as t-butylperoxyacetate, t-butylperoxypivalate, t-butylperoxybenzoate, t-butylmaleic acid hemiperester; t-butylhydroperoxide, methylethylketone peroxide And organic peroxides such as ketone peroxides and 2,2-
Azobisisobutyronitrile, 2,2-azobis (2,
An azo compound such as 4-dimethylvaleronitrile) can be used. Such a polymerization initiator is added in an amount of 0.01 in the raw material liquid.
~ 5 wt% is used. When particularly rapid polymerization is desired, a combination of the above-mentioned peroxide type radical polymerization initiator and a polymerization accelerator,
A so-called redox-based initiator containing a reducing substance as a main component may be used as the polymerization accelerator. The reducing substance may be a known substance that forms a redox, and further, a sulfur compound having a valence of 4 or less such as mercaptans such as glycol dimercaptoacetate and 2-mercaptoethanol acetate; triphenylphosphite, 9 , 10-dihydro-9-oxa-
There are phosphorus compounds such as 10-phosphaphenanthrene-10-oxide. Such a reducing substance is contained in the raw material liquid in an amount of 0.05
~ 5 wt% is used. Further, as the auxiliary component, a hydrogen halide salt of a heavy metal compound and an amine, or a quaternary ammonium halide is optionally used. As the heavy metal compound, a compound of at least one metal selected from iron, copper and cobalt, which is soluble in the monomers, can be mentioned. For example, naphthenic acid salts of these metals, acetylacetone complex salts and the like can be mentioned. Such a heavy metal compound is converted to a metal and is contained in the raw material liquid at 0.05 to
Use 10 ppm. Examples of the hydrogen halide salts or quaternary ammonium halides of amines include amine hydrochlorides such as N, N-dimethyloctylamine and phenethyldibutylamine; tetramethylammonium chloride, trioctylmethylammonium chloride and the like. To be These compounds are contained in the raw material liquid in an amount of 0.01 to 1% by weight.
To use. Further, various additives such as acrylic rubber, stabilizers, plasticizers, polymerization regulators, flame retardants, fillers, dyes and pigments may be added to the raw material liquid mixture as required. The method of injecting the raw material liquid into the mold may be any method as long as the raw material liquid can be filled in the mold. For example, there is a method of injecting into a horizontally opened mold and then closing the mold, or a method of press-fitting from a part of a mating portion of a vertically or slightly inclined and closed mold. The polymerization of the raw material liquid in the mold is carried out by heating the mold to raise the temperature suitable for the polymerization initiator using the raw material liquid,
Polymerize and cure. As a heating method, an air oven,
There are a method using a hot bath, a method of sandwiching in a hot plate such as a hot press, a method of using far infrared rays and a microwave. The time for polymerization and curing is preferably as little unreacted monomer as possible, and is about 5 minutes to 10 hours, although it varies depending on the type of polymerization initiator used and the shape of the molded article. Further, during polymerization and curing, a pressure of about 0.01 to 5 kg / cm ² may be applied for the purpose of preventing warpage or deformation of the molded article due to heat and compensating for volume shrinkage due to polymerization. After the completion of the polymerization and curing, the mold is cooled and the mold is opened, and the molded article having the scratch resistant coating is taken out. According to the method of the present invention, by curing the ultraviolet curable liquid in the air, a cover body for blocking oxygen and a seal with an inert gas are not required, and the productivity is improved. To be done. Further, by polymerizing a raw material liquid containing a polyfunctional unsaturated monomer in a mold on which a scratch resistant film is formed, a synthetic resin molded article becomes a crosslinked polymer, and heat resistance and mechanical strength are also improved. Moreover, the adhesion of the scratch-resistant coating is also improved. EXAMPLES The following examples are given to further illustrate the method of the present invention, but the present invention is not limited thereto. The evaluation of the obtained synthetic resin molded product having a scratch-resistant coating is carried out by the following method.・ Adhesion: Put 100 crosshatch at 1mm intervals,
Performed by a so-called cross-cut test for removing cellophane tape,
The percentage of the number of cross hatches that did not peel was shown in%. -Scratch resistance: # 000 on the surface of the test piece under a load of 1 kg / cm ^2.
The steel wool was pressed while pulling to check for scratches. Example 1 Isophorone diisocyanate isocyanurate (Desmodur Z-4370 manufactured by Sumitomo Bayer Urethane Co.) 210
g, 200 g of pentaerythritol tri, tetraacrylate (tri67: tetra33) and 7 g of trimethylolpropane in the presence of a dibutyltin dilaurate catalyst,
A multi-branched urethane acrylate obtained by reacting at 60 ° C. for 10 hours and 40 g of 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator were mixed and diluted 3 times with toluene to prepare a hard coat liquid on one side of a glass plate with a bar coater. Apply to a thickness of about 5 μm and apply a 120 W / cm metal halide lamp from a distance of 200 mm in air for about 10 seconds 1
Irradiation was performed at 000 mJ / cm ² to obtain a scratch-resistant film. The surface of this film was not sticky. Two glass sheets were made to face each other so that the surface coating was on the inside, and a soft vinyl chloride resin gasket was sandwiched so that the gap was 1 mm to assemble a cell. T-in the cell
Butyl peroxy-2-ethyl hexanoate 0.6% by weight, dimethyloctyl ammonium chloride 0.
06% by weight, glycol dimercaptoacetate 0.6
Wt%, a mixture of 90 parts by weight of a methyl methacrylate partial polymer containing 6 ppm of copper naphthenate (copper content 10% by weight) and 10 parts by weight of tetraethylene glycol dimethacrylate, and 0.1 kg / Polymerization was carried out by heating for 10 minutes under a pressure of cm ² . After cooling, the cell was opened to obtain a resin plate having a scratch resistant film. Adhesion was 100%, and there were no scratches on scratch resistance. Comparative Example 1 A resin plate was obtained in the same manner as in Example 1 except that the scratch resistant coating was not formed on the surface of the glass plate in advance. On the surface of the resin plate, the same multi-branched urethane acrylate-based hard coat liquid used in Example 1 was applied by a bar coater to about 5
The coating was applied in a thickness of μm, and a 120 w / cm metal halide lamp was irradiated in the air from a distance of 200 mm for about 30 seconds to form a scratch-resistant coating. The obtained resin plate having a scratch-resistant film had no scratches on the scratch resistance, but the adhesion was 5
It was 0%.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location // B29L 9:00 4F (72) Inventor Takuhiko Jinno 2-12 Tashiro Nishi, Joto-ku, Osaka City No.13 Koei Chemical Industry Co., Ltd. (72) Inventor Toshito Sakai 2-12-13 Nishi, Saito-ku, Osaka City Koei Chemical Industry Co., Ltd.

Claims (1)

Claim: What is claimed is: 1. An inner surface of a mold is coated with an ultraviolet curable liquid containing urethane acrylate as a main component, and the inner surface of the mold is preliminarily cured by irradiating it with ultraviolet rays to cure it. After forming a scratch film, a synthetic resin raw material liquid consisting of an ethylenically unsaturated monofunctional monomer, an ethylenically unsaturated polyfunctional monomer and a radical polymerization initiator is injected into the template to polymerize and scratch resistance For producing synthetic resin molded products with a protective coating. 2. A method for producing a synthetic resin molded article with a scratch resistant film according to claim 1, wherein the urethane acrylate is a multi-branched urethane acrylate.