JPH0120969B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing a synthetic resin molded article with excellent non-glare properties and scratch resistance.

The synthetic resin produced by the method of the present invention is resistant to scratches and has non-glare properties, that is, by utilizing the characteristics that glare caused by reflected light is suppressed, the presence of reflected light is eliminated. Suitable for use in CRT front panels, meter covers, etc., which can cause a feeling of pleasure or a decrease in work efficiency.

(Prior Art) Today, due to the rapid spread of microcomputers, word processors, etc., the number of devices using CRTs is rapidly increasing. The rapid increase in the use of CRTs has brought to light the problem of discomfort and decreased work efficiency due to the presence of reflected light on the front surface of CRTs when they are used. To address these problems, there is a strong demand for transparent synthetic resins that can suppress glare caused by reflected light, that is, have non-glare properties. Furthermore, since the surface is also provided with scratch resistance, synthetic resins that are transparent, non-glare, and durable have extremely high commercial value.

As a method for manufacturing synthetic resin molded products with non-glare and scratch resistance, a method has been proposed in which a raw material that can form a non-glare and scratch-resistant film after curing is applied to a synthetic resin base material and then cured. has been done. That is, for example, JP-A No. 56-84729 discloses a method using a film-forming resin raw material whose main raw material is a silicon compound, and JP-A No. 57-156832 discloses a method using a film-forming resin raw material containing a silicon compound as the main raw material, and JP-A No. 57-156832 discloses a method using a film-forming resin raw material containing silicon compounds as the main raw material, and JP-A No. 57-156832, etc. A method using a film-forming resin raw material whose main raw material is a compound having the following is disclosed. However, these methods have problems in that the surface irregularities are locally disturbed during coating and curing of the film raw material, which impairs commercial value, and the reproducibility of the degree of surface irregularities is low.

(Problems to be Solved by the Invention) The purpose of the present invention is to overcome the problems of the prior art as described above, and to provide non-glare properties with good reproducibility of surface unevenness without causing local disturbance of surface unevenness. and to provide synthetic resin molded products with excellent scratch resistance.

(Means for Solving the Problems) The present inventor has discovered that, compared to the conventional technique, in which fine surface irregularities are formed from a free surface by polymerization curing to impart non-glare properties, the ability to form a scratch-resistant film is It is better to polymerize the raw material on a surface on which minute irregularities have been formed in advance, and then transfer that surface onto the molded product body. This is a non-glare method that allows for better reproducibility of surface irregularities without causing local irregularities in the surface irregularities. The present invention was completed based on this knowledge.

That is, the method for manufacturing a synthetic resin molded product having a surface with excellent non-glare and scratch resistance according to the present invention involves applying a scratch-resistant film-forming resin raw material to a molding surface on which fine irregularities have been formed in advance. , the film-forming resin raw material is sufficiently polymerized and cured to the extent that it will not swell or dissolve with the base resin raw material injected later, to form a film on the molding surface in advance, and then the base resin is poured into the mold. The method is characterized in that raw materials are injected and polymerized to transfer the previously formed film to the base resin side.

Hereinafter, the method for producing a synthetic resin molded article of the present invention will be explained in more detail.

In the present invention, specific examples of the material constituting the molding surface on which minute irregularities are to be formed include glass, stainless steel, and metals such as aluminum, and these may be surface-treated. Among these, glass and hard chrome-plated metal are cited as preferred examples.

Forming minute irregularities on the molding surface in advance has already been widely practiced, and it is sufficient to select an appropriate method from among these conventional techniques to form minute irregularities on the molding surface.

The form of the minute irregularities formed in advance on the molding surface is not particularly limited and may be appropriately selected depending on the purpose. However, in order to achieve the purpose of the present invention, the gloss of a synthetic resin molded product manufactured by copying the surface of the synthetic resin molded product will be the same as that of a synthetic resin molded product manufactured using the same recipe using a mold with a glass mirror surface instead. It is preferable that minute irregularities are formed on the molding surface to an extent that the gloss is at least 20% lower than the gloss level. The gloss level expressed in the present invention is 60% as measured by method 2 of JIS-Z-8741.
Specular gloss in degrees.

Preferred specific examples of the scratch-resistant film-forming raw material used in the present invention include compounds having two or more acryloyloxy groups or methacryloyloxy groups in the molecule, or polymerizable compositions containing 50% by weight or more of such compounds. can be mentioned. These compounds and polymerizable compositions are preferred because they form a film with excellent scratch resistance and can be rapidly polymerized and cured by irradiation with ultraviolet rays in the presence of a photosensitizer. Productivity is extremely high. In particular, 2 in the molecule
Compounds having 1 or more acryloyloxy groups are particularly preferred because they can be polymerized and cured extremely rapidly by irradiation with ultraviolet rays in the presence of a photosensitizer to form a film with excellent scratch resistance.

Specific examples of compounds having two or more acryloyloxy groups or methacryloyloxy groups in the molecule include polyhydric alcohols and (meth)acrylic acid (meaning "acrylic acid or methacrylic acid",
The same applies hereinafter) or esterified products obtained from these derivatives, or esterified products obtained from polyhydric alcohol, polyhydric carboxylic acid, (meth)acrylic acid, or their derivatives.

Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol with an average molecular weight of about 300 to about 1000,
Propylene glycol, dipropylene glycol, 1,3-propanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,
6-hexanediol, neopentyl glycol (2,2-dimethyl-1,3-propanediol), 2-ethyl-1,3-hexanediol,
Dihydric alcohols such as 2,2'-thiodiethanol and 1,4-cyclohexanedimethanol, other trimethylolpropane (1,1,1-trimethylolpropane), pentaglycerol (1,1,
1-trimethylolethane), glycerol, pentaerythritol (2,2-bishydroxymethyl-1,3-propanediol), diglycerol, dipentaglycerol, and the like.

Obtained from these and (meth)acrylic acid,
Particularly preferred compounds include diethylene glycol (meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,4-butanediol diacrylate, 1,6 -Hexanediol diacrylate, trimethylolpropane tri(meth)acrylate, trimethylol,
Examples include ethane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaglycerol penta(meth)acrylate, dipentaglycerol hexa(meth)acrylate, and the like.

In addition, cross-linked polymerizable compounds obtained from polyhydric alcohols, polycarboxylic acids, (meth)acrylic acids, or their derivatives are basically hydroxyl groups of polyhydric alcohols, polyhydric carboxylic acids, and (meth)acrylic acids. It is obtained by reacting a mixture such that the carboxyl groups of both acids are ultimately equivalent.

Preferred compounds include esterified products obtained by using dihydric alcohol, trihydric alcohol, or a mixture of dihydric alcohol and trihydric alcohol as the polyhydric alcohol, and using a dihydric carboxylic acid as the polyhydric carboxylic acid. can be given. When using a mixture of trihydric alcohol and dihydric alcohol, the molar ratio of trihydric alcohol to dihydric alcohol can be arbitrarily selected. In addition, the molar ratio of dicarboxylic acid and (meth)acrylic acid is
The equivalent ratio of the carboxyl group of divalent carboxylic acid and the carboxyl group of (meth)acrylic acid is 2:1 to
A range of 0:1 is preferred. If the divalent carboxylic acid is in excess of the above range, the viscosity of the resulting ester becomes too high, making it difficult to form a coating film. Examples of divalent carboxylic acids include aliphatic dicarboxylic acids such as succinic acid, adipic acid, and sebacic acid; alicyclic dicarboxylic acids such as tetrahydrophthalic acid and 3,6-endomethylenetetrahydrophthalic acid; phthalic acid; isophthalic acid; Aromatic dicarboxylic acids such as terephthalic acid, thiodiglycolic acid, thiodivaleric acid, diglycolic acid, maleic acid, fumaric acid, itaconic acid, etc., or their chlorides, anhydrides, and esters can be used.

Examples of compounds that can be copolymerized with the above-described compound having two or more acryloyloxy groups or methacryloyloxy groups in the scratch-resistant film forming raw material of the present invention include (meth)acrylic acid, Examples include (meth)acrylic acid alkyl ester, (meth)acryloxyethyl phosphate and other polymerizable acidic phosphoric esters.

Furthermore, when carrying out the present invention, it is preferable to add a polymerization initiator to the film-forming raw material.
On the other hand, polymerization and curing of the film-forming raw material is preferably carried out by photopolymerization using ultraviolet irradiation because the equipment is relatively simple and productivity is high. Therefore, as the polymerization initiator added to the film-forming raw material, a photosensitizer is preferable. Specific examples of such photosensitizers include carbonyl compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, acetoin, benzyl, benzophenone, p-methoxybenzophenone, and tetramethylthiuram monosulfur. Examples include sulfur compounds such as fluoride, tetramethylthiuram disulfide, and the like.

The amount of these photosensitizers added is preferably 0.1 to 10 parts by weight per 100 parts by weight of the unsaturated polymerizable compound in the film-forming raw material. If the amount of the photosensitizer added is too small, the polymerization and curing of the film will be slow, resulting in low productivity, which is undesirable.On the other hand, if the amount added is too large, the weather resistance of the film will tend to deteriorate, which is undesirable.

The specific method for polymerizing and curing the film-forming resin raw material is not particularly limited. However, as mentioned above, photopolymerization by ultraviolet irradiation in the presence of a photosensitizer is particularly preferred because the apparatus is relatively simple and productivity is high.

When polymerizing and curing the film raw material, for example,
As described in Japanese Patent Publication No. 49-36830 and Japanese Patent Publication No. 54-14617, a preferred embodiment is a method in which the coating raw material is closely covered with a cover having no affinity thereto and then polymerized and cured. Furthermore, the first stage of curing of the film is performed by closely covering the cover body which has no affinity with the film, and then the cover body is peeled off from the surface of the film, and then the second stage of the film is further cured in air. Harden the eyes 2
A step-curing method is mentioned as a more specific embodiment.

The thickness of the coating that provides non-glare and scratch resistance of the present invention is preferably in the range of 1 to 100 microns. When the film thickness is less than 1 micron, it is not preferable because sufficient scratch resistance may not be provided in some cases. On the other hand, the film thickness is 100
When it exceeds microns, the synthetic resin molded product having the film on its surface tends to become brittle, which is undesirable.
More preferably, it is between 3 and 20 microns.

In a preferred embodiment of the present invention, the base resin raw material is methyl methacrylate or a partial polymer of a polymerizable unsaturated monomer containing 80% by weight or more of methyl methacrylate.

Examples of polymerizable unsaturated monomers that can be copolymerized with methyl methacrylate include acrylic esters such as methyl acrylate, ethyl acrylate, and 2-ethylhexyl acrylate, methacrylic esters such as ethyl methacrylate, and styrene. and derivatives thereof.

Various commonly used additives may be added to this base resin raw material. Examples of additives include dyes, ultraviolet absorbers, and release agents that facilitate the release of synthetic resin from molds. It is necessary to add a radical polymerization initiator except in exceptional cases.

Specific examples of radical polymerization initiators include 2,
2′-azobis(isobutyronitrile), 2,2′-
Azobis(2,4-dimethylvaleronitrile),
An azo initiator such as 2,2'-azobis(2,4-dimethyl, 4-methoxyvaleronitrile), an organic peroxide such as benzoyl peroxide or lauroyl peroxide, or a combination of an oxidizing agent and a reducing agent. Examples include so-called redox initiators.

When a redox-based initiator is used, heating may not be necessary during polymerization, but usually the polymerization is carried out by heating to 40 to 150°C after pouring into a mold. In particular, it is preferable to complete the polymerization by heating to 50 to 95°C in the first stage and then to 100 to 140°C in the second stage.

(Actions and Effects of the Invention) According to the method of the present invention, a synthetic resin molded product with excellent non-glare properties and scratch resistance can be obtained.
The main features of the method of the present invention are the following two points.

(b) The surface is reproducible because it copies the surface with minute irregularities formed in advance.

(b) Since the formed film has scratch resistance, when it is peeled off from the molding surface as one piece with the synthetic resin base material, it can prevent minute surface scratches that would otherwise occur if the film did not have scratch resistance. Defects caused by scratches do not occur.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples. Parts in the examples represent parts by weight.

The scratch resistance is evaluated by the increase in haze value determined by the falling sand method shown below. That is, the test piece is tilted at an angle of 45° with the horizontal direction and rotated around the vertical axis at a speed of 11 R.PM.
300g of 60 mesh carborundum from 70cm above
is dropped at a speed of 150 g/min, and the increase in haze value is calculated by subtracting the haze value before sand fall from the haze value after sand fall.

Note that the haze value is expressed by the following formula.

Haze value (%) = Total light transmittance - Parallel light transmittance / Total light transmittance ×
100 The smaller the increase in haze value, the better the scratch resistance.

The surface roughness of the sample was expressed by compressing the cross-sectional view of the sample embedded in polyester resin in the width direction.

Example 1 1,6-hexanediol diacrylate
A coating material containing 100 parts and 1.5 parts of benzoin ethyl ether was mixed into a film with a size of approximately 610 mm x 460 mm.
It was cast onto one side of a tempered glass plate having a thickness of 6 mm and having minute irregularities formed on its surface. This was covered with a polypropylene film cover with a tension of 20 microns on all four sides, and a roller was pressed from above.
The film was spread so that no air bubbles remained between the film and the glass plate, and the thickness of the coating material was approximately 20 microns. First, take the item in such a state with a 75mm
Irradiation was performed for 15 seconds from a height of 6 cm using 10 fluorescent chemical lamps (Toshiba FL-20BL) arranged at intervals. After that, the cover film was peeled off from the pre-cured film, and then 30cm
The coating was post-cured by irradiating for seconds. The thus treated glass plate was placed facing the mirror-surfaced untreated glass with the cured film facing inside, and the surrounding area was sealed with a soft vinyl chloride gasket.
A mold was constructed. In the mold, 100 parts of methyl methacrylate partial polymer, 0.01 parts of Tinuvin P (ultraviolet absorber), 0.05 parts of 2,2' azobisisobutyronitrile, 0.05 parts of Nippon Kagaku Kogyo's trade name "EAP" (monoethyl phosphate), A base resin raw material consisting of (mixture with diethyl phosphate) was injected. Note that the spacing between the mold glasses was adjusted so that the resulting resin plate had a thickness of 3 mm. The base resin raw material is heated at 60℃ for 6 hours.
Then, the mixture was heated and polymerized at 120°C for 2 hours. After cooling,
The resin plate was peeled off from the glass plate. No local disturbance of surface irregularities was observed in the obtained resin plate, and the scratch resistance of the surface on the side on which the film was not formed showed an increase in haze value of 55% using the sand drop method. However, on the side where the film was formed, the haze value increased by 12% by the sand drop method, the gloss level was 81%, and it had excellent non-glare properties and scratch resistance. When the surface roughness of this resin plate on the side on which the film was formed was measured, the results shown in FIG. 1 were obtained.

Comparative Example 1 The operation of Example 1 was repeated, except that instead of the tempered glass plate surface having minute irregularities formed on the surface, a scratch-resistant formation treatment was performed on the surface of a mirror-finished tempered glass plate. A 3 mm synthetic resin plate was obtained.

The surface of the resin plate on which the film was formed had an increase in haze value of 12% by sand drop method and had excellent scratch resistance, but the gloss level was 148%.

Comparative Example 2 By repeating the operation of Example 1, except that the scratch-resistant film formation treatment was not performed on the surface of the tempered glass plate with minute irregularities formed on the surface, a thickness of 3
A synthetic resin molded article with a non-glare surface of mm was obtained.

This synthetic resin molded product had a considerable number of small scratches of 2 to 3 mm in length, which were thought to have occurred when it was peeled off from the tempered glass plate, and as a result, the surface irregularities were noticeably disordered.

Example 2 A coating material consisting of 50 parts of trimethylolpropane triacrylate ₄₅ parts of 1,4-butanediol diacrylate Size 1420mm x 1170mm Thickness 10
It was cast onto a tempered glass surface with a diameter of 1.5 mm and minute irregularities formed on the surface. A 12-micron polyester film under tension is applied to the top, and a roller is pressed from above to spread the film so that no air bubbles remain between the film and the glass plate, until the thickness of the coating material is approx.
I set it to 10 microns. First, the object in such a state was passed under 23 fluorescent chemical lamps (Toshiba FL-40BL) arranged at 75 mm intervals at 2 m/min.
passed at a speed of After that, the cover film was peeled off from the pre-cured film, and six high-pressure mercury lamps (Toshiba H4000L/
3) at a speed of 2 m/min to post-cure the film. The thus treated glass plate was placed opposite untreated glass having a mirror surface with the cured film facing inside, and the periphery was sealed with a soft vinyl chloride gasket to form a mold.

A base resin raw material consisting of 100 parts of methyl methacrylate partial polymer, 0.01 part of Tinuvin P (ultraviolet absorber), and 0.01 part of 2,2'-azobis(2,4-dimethylvaleronitrile) was poured into the mold. Note that the interval between the mold glasses was adjusted so that the resulting resin plate had a thickness of 1.5 mm. The mold was immersed in a 65°C water bath for 4 hours and then heated in a 120°C hot air circulating oven for 2 hours to polymerize the base resin raw material. After cooling, the resin plate obtained by peeling from the glass plate showed no local disturbance of surface irregularities, and the surface on which the film was formed showed an increase in haze value of 11% by sand drop method. %, the gloss level was 79%, and it had excellent non-glare properties and scratch resistance. When the surface roughness of this resin plate on the side on which the film was formed was measured, the results shown in FIG. 2 were obtained.

Example 3 A film raw material consisting of 50 parts of dipentaglycerol hexaacrylate, 50 parts of trimethylolpropane triacrylate, and 5 parts of benzoin methyl ether was prepared into a hard film having dimensions of 610 mm x 460 mm and thickness of 2 mm with minute irregularities formed on the surface. It was cast onto the surface of a chrome-plated steel plate. The coating material was rolled out using a roll so that the thickness was about 20 microns. Then, this film raw material was irradiated for 2 minutes with an ultra-high pressure mercury lamp (Jet Line CHM-3000 manufactured by Oak Seisakusho Co., Ltd.) to cure the film. The thus treated chrome plated steel plate was placed facing an untreated chrome plated steel plate with a mirror surface with the hardened film facing inside, and the periphery was sealed with a soft vinyl chloride gasket to form a mold. The mold contained 100 parts of ethyl methacrylate partial polymer, 0.3 parts of 2-hydroxy-4-octoxybenzophenone, 0.0046 parts of carbon black pigment (trade name "ANC919" manufactured by Toyo Ink Mfg. Co., Ltd.), and 0.2 parts of lauroyl peroxide. The base resin raw material was injected. The mold was immersed in a 65°C water bath for 5 hours, and then heated in a hot air circulation oven at 120°C for 2 hours to polymerize the base resin raw material.
After cooling, the resin plate obtained by peeling from the chrome-plated steel plate showed no local irregularities in the surface irregularities, and the surface on which the film was formed showed no increase in haze value by the falling sand method. The gloss was 51% and had excellent non-glare properties and scratch resistance. When the surface roughness of this resin plate on the side on which the film was formed was measured, the results shown in FIG. 3 were obtained.

[Brief explanation of drawings]

Figures 1, 2, and 3 are Example 1, respectively.
This figure shows the surface roughness of the synthetic resin plates obtained in Examples 2 and 3 on the side where the film was formed.

Claims (1)

[Scope of Claims] 1. A scratch-resistant film-forming resin raw material is applied to the molding surface on which fine irregularities have been formed in advance, and the resin material is coated to the extent that it will not swell or dissolve by the base resin raw material that is injected later. The film-forming resin raw material is sufficiently polymerized and cured to form a film on the molding surface of the mold, and then the base resin raw material is injected into the mold and polymerized, and the preformed film is applied to the base resin side. 1. A method for producing a synthetic resin molded article having a surface with excellent non-glare and scratch resistance, characterized by the ability to transfer to 2 The scratch-resistant film-forming resin raw material contains 2 in the molecule.
A compound having 1 or more acryloyloxy groups or methacryloyloxy groups, or
The method for producing a synthetic resin molded article according to claim 1, which is a polymerizable composition containing 50% by weight or more. 3. The method for producing a synthetic resin molded article according to claim 2, wherein the scratch-resistant film-forming resin raw material is polymerized and cured by photopolymerization using ultraviolet irradiation. 4. The method for producing a synthetic resin molded article according to claim 1, wherein the scratch-resistant coating has a thickness of 1 micron to 100 microns.