JPH0225668B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a synthetic resin molded product that is hard to be scratched and has excellent non-glare properties.

(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 from the front surface of CRTs encountered when using them. To address these issues, glare caused by reflected light was suppressed. That is, there is a strong demand for transparent synthetic resins that have non-glare properties. Furthermore, synthetic resins that have transparency and non-glare properties as well as durability have become extremely valuable as commercial products because of their surface scratch resistance.

As a method for manufacturing synthetic resin molded products with non-glare and scratch resistance, after the synthetic resin base material has hardened, a raw material that forms a film with non-glare and scratch resistance is applied to the synthetic resin base material. ,
A method of curing to impart non-glare properties and scratch resistance has been proposed. That is, for example, JP-A No. 56-84729 discloses a method using a film-forming raw material whose main raw material is a silicon-based compound, and JP-A No. 57-156832 discloses a method using a film-forming raw material containing silicon compounds as the main raw material, and JP-A No. 57-156832, etc. A method is disclosed in which a film-forming raw material containing a compound having the following as a main raw material is applied. However, these methods require coating and coating of film-forming raw materials.
There are problems in that the surface irregularities are locally disturbed during curing, which impairs commercial value, and it is difficult to obtain reproducibility of the degree of surface irregularities.

(Problems to be Solved by the Invention) An object of the present invention is to overcome the problems of the prior art,
It is an object of the present invention to provide a synthetic resin molded product that has good reproducibility of surface irregularities without causing local irregularities in surface irregularities, and has excellent non-glare properties and scratch resistance.

(Means for Solving the Problems) The present invention provides a method in which raw materials for forming an abrasion-resistant film are prepared in advance, compared to the conventional method in which fine surface irregularities are formed from a free surface by polymerization curing to impart non-glare properties. It is possible to obtain a non-glare surface with good reproducibility of surface irregularities by polymerizing on a surface with appropriately minute irregularities and copying the surface without causing local disturbance of the surface irregularities. It was completed based on the knowledge of

In other words, the method for producing a synthetic resin molded product with excellent non-glare and scratch resistance according to the present invention uses a raw material for forming a scratch-resistant film between a molding surface on which fine irregularities are formed in advance and a synthetic resin base material. It is characterized in that the raw material is polymerized and cured in a state in which the synthetic resin substrate is interposed, and then the scratch-resistant coating is peeled off from the molding surface as one piece with the synthetic resin base material.

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 formed include glass, metals such as stainless steel or aluminum, and surface-treated materials thereof, and synthetic resins. Among these, preferred specific examples include scratch-resistant and durable glass and surface-treated metal. Specific examples of the shape include a plate-like shape, a drum shape, and a cylindrical shape. Forming minute irregularities on the molding surface of a mold in advance is already widely practiced, and it is only necessary to select an appropriate method from among these conventional techniques to form minute irregularities on the molding surface of the mold. .

The form of 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 the synthetic resin molding machine manufactured by copying the uneven surface must be at least 20% lower than the gloss of the synthetic resin base material before non-glare imparting treatment. Preferably, minute irregularities are formed on the molding surface. Note that the glossiness expressed in the present invention refers to the specular glossiness at 60 degrees measured by method 2 of JIS-Z-8741.

The synthetic resin base material used in the present invention is a transparent synthetic resin that is rigid at room temperature and has excellent transparency.
It is particularly suitable for use in CRT front panels and the like. Specific examples include polymethyl methacrylate, polymers whose main constituent unit is methyl methacrylate, polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, polycarbonate, cellulose acetate butyrate, etc. can be mentioned.

The synthetic resin base material is preferably a plate-shaped product, and its thickness is usually 0.2 to 20 mm.

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 not only form a film with excellent scratch resistance, but also rapidly polymerize and cure when irradiated with ultraviolet light in the presence of a photosensitizer. This is based on the fact that it is possible to increase productivity and have extremely high productivity. In particular, compounds having two or more acryloyloxy groups in the molecule are particularly preferred because they polymerize and cure extremely rapidly when irradiated with ultraviolet rays in the presence of a photosensitizer, forming 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, hereinafter the same) or derivatives thereof. Examples thereof include esterified products obtained from polyhydric alcohols, polyhydric carboxylic acids, and (meth)acrylic acids or derivatives thereof.

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 di(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, trimethylolethane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaglycerol penta(meth)acrylate, di Examples include pentaglycerol hexa(meth)acrylate.

In addition, cross-linked polymerizable compounds obtained from polyhydric alcohols, polycarboxylic acids, (meth)acrylic acids, or their derivatives are basically the 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. 3
When using a mixture of a dihydric alcohol and a dihydric alcohol, the molar ratio of the trihydric alcohol to the dihydric alcohol can be arbitrarily selected. Also, 2
The molar ratio of divalent carboxylic acid and (meth)acrylic acid is the carboxyl group of divalent carboxylic acid and (meth)acrylic acid.
The equivalent ratio of acrylic acid to carboxyl group is 2:1
It is preferable that it is in the range of ~0:1. 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.

Compounds that can be copolymerized with the above-mentioned compound having two or more acryloyloxy groups or methacryloyloxy groups in the molecule that can be blended into the scratch-resistant film forming raw material of the present invention include (meth)acrylic acid; Examples include polymerizable acidic phosphate esters such as (meth)acrylic acid alkyl esters and (meth)acryloxyethyl phosphates. 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, a photosensitizer is preferable as the polymerization initiator added to the film-forming raw material. 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 photosensitizer added is too small, the polymerization and curing of the film will be slow, resulting in low productivity. On the other hand, if the amount added is too large, it tends to cause a decrease in the weather resistance of the film.

The specific method for polymerizing and curing the film-forming raw material of the present invention is not particularly limited, but as mentioned above, since the equipment is relatively simple and the productivity is high, UV irradiation in the presence of a photosensitizer is used. Particularly preferred are photopolymerization methods.

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.
Furthermore, within the above range, it is more preferably 3 to 20 microns.

As a method for making the film forming raw material exist between the molding surface and the synthetic resin base material, after applying the film forming raw material to the molding surface or the synthetic resin base material,
Specific examples include a method in which the other material is pressed onto the film-forming raw material using a press roll or the like, and the film thickness is adjusted while removing air bubbles.

When photopolymerizing the film-forming raw material thus present, it is generally effective to irradiate ultraviolet rays through the synthetic resin base material. However, when using a synthetic resin base material that is opaque to ultraviolet rays, it is effective to use glass as a mold and irradiate ultraviolet rays through the glass.

There are cases in which the adhesion between the film and the synthetic resin base material is dramatically improved by bringing the synthetic resin base material and/or film-forming raw material into contact in a heated state. In particular, for polymethyl methacrylate and polymers having methyl methacrylate as the main constituent unit, this heating has a remarkable effect on improving adhesion.

(Effects of the Invention) According to the present invention, since the uneven surface formed in advance on the molding surface is copied, the resulting synthetic resin molded product does not have local disturbances in the surface unevenness and has high reproducibility of the surface unevenness. Very good. Furthermore, since the formed film has scratch resistance, it does not cause minute surface scratches when it is peeled off from the molding surface as one piece with the synthetic resin base material.

Thus, since the synthetic resin molded product obtained by the method of the present invention has both excellent non-glare properties and scratch resistance, non-glare properties are required because the presence of reflected light causes discomfort and reduces work efficiency. In addition, products that require scratch resistance, such as
Suitable for use as CRT front plates, meter covers, etc.

(Example) Hereinafter, the present invention will be described 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 x 100 The smaller the increase in haze value, the better the scratch resistance.

The surface roughness of the sample was expressed by the cross-sectional view of the sample embedded in the polyester resin compressed in the width direction (Figures 2, 3 and 4).

Example 1 A film-forming raw material consisting of 70 parts of trimethylolpropane triacrylate, 30 parts of 1,6-hexanediol diacrylate, and 3 parts of benzoin ethyl ether was prepared in an area of approximately 610 mm x 460 mm.
It was cast onto a tempered glass surface with a thickness of 6 mm and minute irregularities formed on the surface, and a colorless and transparent polycarbonate resin plate (Dialight 1001 manufactured by Mitsubishi Rayon Co., Ltd.) with a thickness of 1 mm was placed on top of it. The resin plate was placed on the plate and spread with a roller from above so that no air bubbles remained between the resin plate and the glass, so that the thickness of the film-forming raw material was approximately 8 microns. Things in such a state,
First, 10 fluorescent chemical lamps (Toshiba FL-20BL) arranged at 75 mm intervals were used to irradiate the glass side for 1 minute from a height of 6 cm. After that, the glass plate was peeled from the polycarbonate resin plate on which the film was formed, and then it was removed from a height of 20 cm using two high-pressure mercury lamps (Toshiba H2000L) arranged at 400 mm intervals.
The surface on which the film was formed was irradiated for 30 seconds to post-cure the film.

No local irregularities in the surface irregularities were observed on the resin plate obtained in this way, and on the side where the film was formed, the haze value increased by 12% by the falling sand method, and the gloss level increased by 81%.
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.

In addition, the increase in haze value of the polycarbonate resin plate before forming the film by the sand drop method was 67%, and the gloss level was 167%.

Comparative Example 1 The film raw material was a methyl methacrylate partial polymer (polymer content
22%) 100 parts benzoin ethyl ether By repeating the procedure of Example 1 except for replacing 3 parts with 3 parts and changing the irradiation time with a fluorescent chemical lamp to 10 minutes, a synthetic resin molded product with a non-glare surface was produced. 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 disturbed.

Example 2 100 parts of 1,4-butanediol diacrylate,
A film-forming raw material mixed with 1.5 parts of benzoin ethyl ether was cast onto a tempered glass surface with an area of approximately 610 mm x 460 mm and a thickness of 6 mm with minute irregularities formed on the surface, and then heated to 45°C. heated thickness 3mm
A colorless and transparent methacrylic resin plate (Acrylite L#001 manufactured by Mitsubishi Rayon Co., Ltd.) is placed on top, and the film is spread using a roller so that no air bubbles remain between the resin plate and the glass. The thickness was set to approximately 10 microns. The material in such a state was first irradiated from the methacrylic resin plate side for 1 minute from a height of 6 cm using 10 fluorescent chemical lamps (FL-20BL manufactured by Toshiba) arranged at 75 mm intervals. After that, the glass plate was peeled off from the methacrylic resin plate on which the film was formed, and then a 20 cm
The film was post-cured by irradiating the surface on which the film was formed from a height of 30 seconds for 30 seconds. The side of the thus obtained resin plate on which the film was formed had an increase in haze value of 11% by sand drop method, a gloss level of 79%, and was excellent in non-glare properties and scratch resistance. When we measured the surface roughness of this resin plate on the side where the film was formed, it was found that
The results shown in the figure were obtained.

Furthermore, before the film was formed, the haze value of the methacrylic resin plate measured by the sand drop method increased by 55%, and the gloss level increased by 148%.

Example 3 Methyl methacrylate-methyl acrylate copolymer premixed according to a conventional method using the apparatus shown in Figure 1.
100 parts (Methyl methacrylate/methyl acrylate composition ratio = 94.2/5.8 (weight ratio) Intrinsic viscosity number (25°C, chloroform solvent) = 0.072/g) Tinuvin P (manufactured by Ciba Geigy) 0.01 part The synthetic resin plate 3 was melt-kneaded in a plasticizing extruder 1, extruded from a die 2, and continuously supplied to a glass hollow roll 6 whose surface had minute irregularities via gloss rolls 4 and 5.

On the other hand, a film-forming raw material 7 consisting of 100 parts of trimethylolpropane triacrylate and 2 parts of benzoin ethyl ether is continuously supplied to the roll 6 by a roll coater 8 so as to have a thickness of about 15 microns. Board 3
and roll 6. Thereafter, the film-forming raw material was cured by irradiating ultraviolet rays from a high-pressure mercury lamp (H2000L manufactured by Toshiba Corporation) 9.

By doing this, a scratch-resistant film 10 having a thickness of 3 is formed on the surface with fine irregularities.
A methacrylic resin plate 11 with a width of 550 mm and a width of 550 mm was obtained.

In the thus obtained resin plate, no local disturbance of surface irregularities was observed, and on the side where the film was formed, the haze value increased by 13% by the falling sand method, and the gloss level increased by 55%.
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. 4 were obtained.

Comparative Example 2 Scratch resistance was continuously improved by repeating the same operations as in Example 3, except that a mirror-glossy glass hollow roll was used in place of the roll 6 with minute irregularities formed on the surface in Example 3. A methacrylic resin plate was obtained.

The gloss level of this resin plate on the side where the film is formed is
It was 147%.

Comparative Example 3 In Example 3, the film-forming raw material 7 was not supplied to the roll 6 on which minute irregularities were formed, and the synthetic resin plate 3 supplied from the plasticizing extruder 1 was directly pressed onto the roll 6. Except for this, methacrylic resin plates were continuously obtained by repeating the same operations as in Example 3.

The surface of this resin plate in contact with the roll 6 had non-glare properties similar to the resin plate obtained in Example 3, but the surface of the resin plate in contact with the roll 6 had a non-glare property, which was thought to have occurred when the resin plate was released from the roll 6. Parallel many lengths 1
Small scratches of ~2 mm were generated, which caused noticeable irregularities in the surface irregularities.

[Brief explanation of drawings]

FIG. 1 shows an apparatus used to carry out the method of the present invention for continuously producing a synthetic resin plate having excellent non-glare properties and scratch resistance using a glass hollow roll having minute irregularities formed on its surface. FIGS. 2, 3, and 4 show the surface roughness of the coated side of the synthetic resin plates obtained in Example 1, Example 2, and Example 3, respectively. Reference numbers in FIG. 1 are as follows. 1: Plasticizing extruder, 2: Dice, 3: Thermoplastic synthetic resin plate, 4, 5: Glazing roll, 6: Glass hollow roll with minute irregularities formed on the surface.
7: film-forming raw material, 8: roll coater, 9: mercury lamp, 10: scratch-resistant cured film, 11: non-glare, scratch-resistant synthetic resin plate.

Claims (1)

[Scope of Claims] 1. A raw material for forming a scratch-resistant film is interposed between a synthetic resin base material and a molding surface on which fine irregularities have been formed in advance, and the raw material is polymerized and cured, and then the scratch-resistant film-forming raw material is polymerized and cured. A method for manufacturing a synthetic resin molded product having a surface with excellent non-glare and scratch resistance, characterized by peeling an abrasion-resistant film from a molding surface integrally with a synthetic resin base material. 2 The synthetic resin base material is composed of polymethyl methacrylate, a polymer whose main constituent unit is methyl methacrylate, polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, polycarbonate, cellulose acetate butyrate A method for producing a synthetic resin molded article according to claim 1, wherein the synthetic resin molded article is selected from the group consisting of: 3. Claim 1, wherein the scratch-resistant film-forming raw material is a compound having two or more acryloyloxy groups or methacryloyloxy groups in the molecule, or a polymerizable composition containing 50% by weight or more of the compound, or 2. The method for producing a synthetic resin molded product according to item 2. 4. The method for producing a synthetic resin molded article according to claim 3, wherein the raw material for forming the scratch-resistant film is polymerized and cured by photopolymerization using ultraviolet irradiation. 5. The method for producing a synthetic resin molded article according to any one of claims 1 to 4, wherein the scratch-resistant coating has a thickness of 1 micron to 100 microns. 6. Forming minute irregularities on the molding surface in advance to the extent that the gloss of the surface of the synthetic resin molded product imparted with non-glare properties is at least 20% lower than the gloss of the synthetic resin base material before non-glare imparting treatment. A method for producing a synthetic resin molded article according to claim 1.