JP2003002937A - Molded product excellent in light transmission characteristics - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molded product comprising a polystyrene resin excellent in light transmission, having light dispersibility without visualizing a light source image and having high glossiness. SOLUTION: This molded product for light transmission comprises a rubber reinforced polystyrene resin in which a rubbery polymer is dispersed in a matrix comprising the polystyrene resin. The rubber reinforced polystyrene resin has a specific particle size distribution and a gel content of a specific range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light-transmitting molded product made of a styrene resin having excellent light-transmitting properties, particularly a light-transmitting molded product useful as a lighting fixture or a light-transmitting industrial part.

[0002]

2. Description of the Related Art Light-transmissive molding having a function of covering light sources such as lighting equipment (covers, fades, etc.) and light-transmissive industrial parts (keys, buttons, covers, keyboards of electronic musical instruments, housings, etc.). For products, there is a demand from the market that light transmission is required but the contour and position of the light source cannot be clearly seen. In other words, there is a demand for a light-transmitting molded product that has excellent light-transmitting properties, yet has a light-diffusing property in which a light source image does not appear, and has a high glossiness.

Conventional light-transmitting molded products made of styrene-based resin have satisfactory light-transmitting properties, but the outline of the light source
Since the position was clearly known, the product was inferior in terms of commerciality as a light-transmitting molded product and could not be used as it was. Conventionally, this problem has been dealt with by a method of blending a light diffusing agent with a styrene resin. As the light diffusing agent, an inorganic light diffusing agent such as barium sulfate or an organic light diffusing agent has been used. However, it is difficult to control the uniformity of the addition of such a light diffusing agent, and it is necessary to add a large amount, so that there is a problem in economic efficiency, and not only the heat resistance and weather resistance of the styrene resin are lowered, but also the so-called Since it has a bad influence on the problem of yellowing in the dark, an alternative method to the blending of the light diffusing agent has been longed for.

[0004]

DISCLOSURE OF THE INVENTION The present invention is for a light-transmitting material made of a rubber-reinforced styrene resin, which satisfies the requirements of excellent light-transmitting property and the contour / position of the light source not being clearly visible. It is an object to provide a molding material.

[0005]

Means for Solving the Problems As a result of earnest studies on means for achieving the above-mentioned object, the present inventor has found that as a material for a light-transmitting molded article, it contains dispersed particles having a specific particle size distribution and contains a specific gel. It was found that the use of a rubber-reinforced styrene-based resin, which is a ratio, is effective in solving the above problems, and has completed the present invention. That is, the present invention is a rubber-reinforced styrenic resin in which a rubber-like polymer is dispersed in particles in a matrix made of a vinyl aromatic polymer,
(1) The particle size of dispersed particles composed of a rubber-like polymer is 0.2 to 3.0 μm according to Coulter Multisizer analysis.
From the rubber-reinforced styrenic resin, the cumulative volume ratio of the dispersed particles of m is 90% or more of the total cumulative volume of all the dispersed particles, and (2) the gel content by toluene is 15 to 30%. It is a molded product for light transmission.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. The rubber-reinforced styrenic resin of the present invention is a high-impact polystyrene to which a rubber-like substance such as synthetic rubber is added, and more specifically, the rubber-like polymer is dispersed in particles in a matrix made of a vinyl aromatic polymer. In general, a rubber-like polymer is dissolved in a vinyl aromatic monomer (and a liquid containing an inert solvent), and is subjected to bulk polymerization, bulk suspension polymerization, or solution while stirring. It can be obtained by polymerizing, precipitating a rubber-like polymer and granulating it.

As the vinyl aromatic monomer forming the above vinyl aromatic polymer, styrene, o-methylstyrene, p-methylstyrene, m-methylstyrene, 2,4
-Alkyl-substituted styrenes such as dimethyl styrene, ethyl styrene, α-methyl styrene, etc. are mentioned, and a typical one is styrene. You may use together 2 or more types of these. Further, other copolymerizable monomers in addition to the vinyl aromatic monomer, methyl methacrylate, ethyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate,
One or more of acrylic acid (methacrylic acid) ester-based monomers such as 2-ethylhexyl acrylate and cyclohexyl acrylate, and vinyl cyanide monomers such as acrylonitrile and methacrylonitrile may be used in combination. .

Examples of the rubber-like polymer of the present invention include polybutadiene, styrene / butadiene copolymer, polyisoprene, butadiene / isoprene copolymer, natural rubber, ethylene / propylene copolymer, and the like.
Polybutadiene and styrene-butadiene copolymer are preferred. The content of the rubbery polymer is 2 to 30% by weight, preferably 5 to 5% by weight, based on the rubber-reinforced styrene resin.
It is 15% by weight. If the content of the rubber-like polymer is less than 2% by weight, impact strength is insufficient, and if it exceeds 30% by weight, light transmittance is insufficient, which is not desirable.

In the present invention, the rubber-like polymer is dispersed in the form of particles. When the rubber-reinforced styrenic resin is dissolved in dimethylformamide, the particle size of the dispersed particles made of the rubber-like polymer dispersed in the dimethylformamide solution is 0.2 in the Coulter Multisizer analysis.
The cumulative volume ratio of dispersed particles having a particle size of ˜3.0 μm must be 90% or more of the total cumulative volume of all dispersed particles.
The particle size is preferably 0.4 to 2.5 μm, more preferably 0.8 to 2.0 μm. Particle size is 0.2 μm
If the dispersed particles of less than 90% are present in an amount of not less than 90% of the total cumulative volume, the rubber particles for blocking light rays are insufficient and the light diffusibility is lowered, which is not desirable. On the other hand, when 90% or more of the dispersed particles having a particle size of more than 3.0 μm are present, the light transmittance is lowered,
The glossiness is also lowered, which is not desirable.

The cumulative volume ratio of dispersed particles having a particle size of 0.2 to 3.0 μm is 90% of the total cumulative volume of all dispersed particles.
When it is less than%, the light diffusivity is lowered, or the light transmittance and the gloss are lowered, which is not desirable. The particle size can be controlled to be small by strengthening the shear added by a mixer having a stirring blade when polymerizing the rubber-reinforced styrene resin. The rubber-reinforced styrene resin of the present invention has a gel content of 15 to 3 with toluene.
It needs to be 0%. When the gel content by toluene is less than 15%, the rubber particles that block light rays are insufficient to reduce the light diffusibility, and when the gel content exceeds 30%, the light transmittance is reduced, which is desirable. Absent.

The reason why the rubber-reinforced styrenic resin containing dispersed particles having a specific particle size distribution and having a gel content in a specific range as described above exhibits excellent light transmission characteristics is considered as follows. There is. That is, in the case of a transparent resin having a thickness of about 2 mm, if dispersed particles having a specific sharp particle size distribution are uniformly dispersed in the matrix, the gaps between the dispersed particles are sewn to cause moderate diffuse reflection inside. At the same time, scattered light passes from the back of the molded product to the front. However, at this time, if the particle size of the dispersed particles is small or the amount is small, the light directly goes out from the back to the front and the light source is clearly visible. On the other hand, it is presumed that, when there are many dispersed particles or the particle size is large, light cannot pass at all, or unevenness is generated on the surface to reduce the glossiness. The rubber-reinforced styrenic resin of the present invention,
Various additives can be added according to the purpose. A benzotriazole-based ultraviolet absorber and a hindered amine-based light stabilizer may be added for improving weather resistance.

The benzotriazole-based compound which can be used in the present invention is an ultraviolet absorber, and a specific example thereof is 2- (2H-benzotriazol-2-yl) -P.
-Cresol, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-
Chlorobenzotriazole, 1,2,3-benzotriazole, 1- [N, N-bis (2-ethylhexyl) aminomethyl] benzotriazole and the like can be mentioned. The amount of the benzotriazole-based ultraviolet absorber blended in the present invention is 0.01 to 5 parts by weight, preferably 0.1 to 1 part by weight, based on 100 parts by weight of the rubber-reinforced styrene resin. If it is less than 0.01 parts by weight, the effect on the weather resistance is insufficient, and if it exceeds 5 parts by weight, the impact strength decreases, which is not preferable.

The hindered amine compound which can be used in the present invention is a light stabilizer, and specific examples thereof include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate and bis (1,2,2,2). 2,6,6-pentamethyl-
4-piperdil) sebacate, 1- [2- [3- (3,
5-di-t-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-t
-Butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine, 8-
Benzyl-7,7,9,9-tetramethyl-3-octyl-1,3,8-triazaspiro [4,5] undecane-2,4-dione, 4-benzoyloxy-2,2
6,6-tetramethylpiperidine and the like can be mentioned. The amount of the hindered amine compound compounded in the present invention is 0.01 with respect to 100 parts by weight of the rubber-reinforced styrene resin.
-5 parts by weight, preferably 0.1-1 part by weight. 0.
If it is less than 01 parts by weight, the effect on the weather resistance is insufficient, and if it exceeds 5 parts by weight, the impact strength decreases, which is not preferable.

Further, the rubber-reinforced styrene resin of the present invention may contain a sulfur chelate compound in order to improve so-called dark yellowing. The yellowing in the dark after exposure to ultraviolet rays in the present invention is a yellowing phenomenon that occurs when the resin is irradiated with ultraviolet rays and then stored in the dark for a long period of time. Further, as a characteristic thereof, it has been conventionally known that the yellowing phenomenon is remarkably promoted when the atmosphere in a dark place is high temperature and high humidity. Therefore, it is a phenomenon that occurs in a completely different process from yellowing due to heat or exposure. In the present invention, the yellowing phenomenon is called dark yellowing.

The sulfur-based chelate compound that can be used in the present invention is a sulfur-based chain transfer agent, and a thiol represented by the following general formula (1) is preferable. R ¹ -SH (1) (In the formula, R ¹ represents an alkyl group having 6 to 25 carbon atoms, a phenyl group, an allyl group, or an ester.) Specific examples of the sulfur-based chelate compound include β-mercaptopropionic acid. -2-ethylhexyl, normal dodecyl mercaptan, normal octyl mercaptan, 2-
Examples thereof include mercaptobenzimidazole, 2-mercapto-6methyl-benzimidazole and 2-mercaptobenzothiazole.

The amount of the sulfur-based chelate compound added is 0.01 to 5 with respect to 100 parts by weight of the rubber-reinforced styrene-based resin.
Parts by weight, preferably 0.1 to 1 part by weight. 0.01
If it is less than 5 parts by weight, the effect of improving yellowing in the dark is insufficient, and if it exceeds 5 parts by weight, impact strength is lowered, which is not preferable. A phenolic compound may be added for the purpose of preventing oxidation and improving heat resistance. The phenolic compound that can be used in the present invention is a phenolic antioxidant represented by the following general formulas (2) and (3), and the substituent R ² in the formula is a phenyl group having 8 to 40 carbon atoms or An allyl group is preferred. ^{R 2 -OH (2) HO-} R 2 -R 2 -OH (3)

Specific examples of the phenolic antioxidant include 2,6-di-t-butyl-p-cresol, stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, Tetrakis [methylene-3
(3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, n-octadecyl-3
-(3 ', 5'-di-t-butyl-4'-hydroxyphenyl) -propionate, 2,2'-methylene-bis- (4-methyl-6-t-butylphenol), 2-t
-Butyl-6- (3'-t-butyl-5'-methyl-
2'-hydroxybenzyl) -4-methylphenyl acrylate, 4,4'-butylidene-bis- (3-methyl-6-butylphenol) and the like can be mentioned. The amount of the phenolic antioxidant blended in the present invention is 0.01 to 5 parts by weight based on 100 parts by weight of the rubber-reinforced styrene resin.
It is preferably 0.1 to 1 part by weight. If it is less than 0.01 parts by weight, the effect on the thermal stability is insufficient, and if it exceeds 5 parts by weight, the impact strength decreases, which is not preferable.

In the present invention, a benzotriazole compound as an ultraviolet absorber, a hindered amine compound as a light stabilizer, a sulfur chelate compound, and a phenol compound are compounded in a rubber-reinforced styrene resin by a conventional method, for example, For example, a method of melting and mixing with other additives together with an extruder is used. By using a suitable additive formulation as described above, it is possible to obtain a light-transmitting molded product with a rubber-reinforced styrene resin having excellent light-transmitting properties, excellent weather resistance, and dark yellowing. it can. Further, the rubber-reinforced styrene resin of the present invention may be used in combination with additives such as heavy metal deactivators, antistatic agents, lubricants, titanium oxide, metal soaps, fillers, processing aids and pigments, if necessary. You can also

In the present invention, the dispersed particle size of the rubber-like polymer was measured as follows. (1) Sample preparation 2.1 g of dried ammonium thiocyanate was weighed,
This was dissolved in 190 g of dimethylformamide. The obtained solution was filtered through a membrane filter, and the dust was thoroughly examined to obtain an electrolytic solution. 0.3 g of the rubber-reinforced styrene resin was weighed and added to 30 g of the electrolytic solution, and the mixture was stirred and dissolved. The obtained solution was subjected to the next measurement as a solution for measuring particle diameter.

(2) Particle size measurement A Coulter Multisizer (SOFTWARE LEVEL 1.8, manufactured by Nikkaki Co., Ltd.) was used to pass the measurement solution through an aperture tube of 30 μm, and then the particle size was measured. The measurement conditions are as follows. Sample concentration: 1%, PIDS concentration: 29%, Optical model: dmf.omd, LS130: Liquid module, Software: 1.53 Range of dispersed particle size measured by this measurement (minimum particle size to maximum particle size), specified particle The proportion of dispersed particles in the diameter range is determined.

In the present invention, the gel content of toluene in the rubber-reinforced styrenic resin was measured as follows. (1) About 1 g (W1) of rubber-reinforced styrene resin and 20 ml of toluene are added to a precipitation tube (50 ml) and shaken with a shaker for 60 minutes. It was confirmed that the resin was completely dissolved. (2) Centrifugation was performed using a centrifuge. The settling tube was taken out and decanted. (3) Removal of solvent (using a vacuum dryer, 160 ° C., 45
Min treatment, then 160 ° C, vacuum degree 10mmHg or less, 1
After treatment for 5 minutes), the weight (W2) was measured. (4) The gel content was calculated as follows. Gel content (%) = (W2 / W1) × 100

In the present invention, the evaluation of the light transmission characteristics was performed as follows. (1) Light transmittance: made of rubber-reinforced styrene resin 2
A red light emitting diode was installed at a position 1 cm below the mm-thick plate, and it was judged whether or not red light could be sensed when visually observed from above the plate. ○: Red light is visible ×: Red light is not visible (2) Gloss: 20 cm due to rubber-reinforced styrene resin
Form a square plate with a thickness of 2 mm, place a blackboard under it, and place it horizontally on a desk. A fluorescent lamp was placed at a position at an angle of 45 degrees from the vertical and at a distance of 50 cm from the center of the flat plate, and when the flat plate was viewed from the diametrically opposite angle of 45 degrees, the image was judged. ○: The outline of the fluorescent lamp is clearly visible ×: The outline of the fluorescent lamp is blurred

(3) Light diffusivity: A red light emitting diode is installed 1 cm below a flat plate made of rubber-reinforced styrene resin and having a thickness of 2 mm.
Judged by the image of ED ◎: The outline of the LED cannot be confirmed at all ○: The outline of the LED cannot be confirmed and appears blurred ×: The outline of the LED can be confirmed (4) Yellowing resistance in a dark place: 2 mm thick flat plate made of rubber-reinforced styrene resin , Sunshine Weatherometer (B
After irradiation for 48 hours at a P temperature of 63 ° C. without rain), the test sample was allowed to stand in an oven at 80 ° C. for 300 hours (in a dark place), and the color change of the test sample was evaluated. ◯: Color change is slight X: Color change is noticeable

[0024]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

Example 1 Mixture I shown below is continuously added as a first stream to a 2.4 liter first polymerizer at a feed rate of 2 liters / hour. Mixture I Polybutadiene rubber 9.6% by weight [Structure of 18% vinyl, 33% cis and 49% trans as analyzed by an infrared spectrophotometer by the Morello method] Styrene 75.4% by weight Ethylbenzene 15.0% by weight Total 100 Parts by weight 2- (2H-benzotriazol-2-yl) -p-cresol 0.2 parts by weight bis (2,2,6,6, -tetramethyl-4-piperidyl) sebacate 0.3 parts by weight 1,1 -Bis (t-butylperoxy) cyclohexane 0.075 parts by weight Stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate 0.15 parts by weight α-methylstyrene linear dimer 0.075 The weight of the first polymerization machine was 97 ° C.

As a second stream, the following mixture II is continuously added to a 6.2 liter second polymerizer at a feed rate of 1 liter / hour. Mixture II Styrene 89.7% by weight Ethylbenzene 10.3% by weight Total 100 parts by weight Mineral oil 3.1 parts by weight The temperature of the second polymerization machine was 130 to 140 ° C.

These first and second streams are 0.
It has a capacity of 5 liters, the gap between the tip of the stirring blade and the wall of the mixer is 2.5 mm, and 6 stages of stirring rods are installed in the axial direction. It is introduced into a stirrer and mixed at a rotation of 100 rpm. Further, it was fed to a third polymerization machine of 6.2 liters and the temperature was 112 to 120.
Polymerized at ° C and stirred to reduce the average particle size of the rubbery material in the pellets. The solid substance concentration at the outlet was 53% by weight. Further, this mixture was fed into a 6.2-liter fourth polymerization machine and polymerized at a temperature of 140 to 155 ° C. The obtained polymer was fed to an extruder with 2 vents, and 2
Volatile components were removed under reduced pressure of −735 mmHg at 30 ° C., the molten strand was drawn out from the die, cooled with water, and finely cut with a cutter to continuously produce cylindrical pellets.

Example 2 Sulfur-based chelate compound; (b): 0.2 parts by weight of 2-ethylhexyl β-mercaptopropionate was added to the pellets produced in Example 1 and melt-kneaded uniformly with a single-screw extruder. After that, it was processed into pellets again.

[0027]

Example 3 Mixture I shown below is continuously added to a 2.4 liter first polymerizer as a first stream at a feed rate of 2 liters / hour. Mixture I Polybutadiene rubber 9.6% by weight [Structure of 18% vinyl, 33% cis and 49% trans as analyzed by an infrared spectrophotometer by the Morello method] Styrene 75.4% by weight Ethylbenzene 15.0% by weight Total 100 Parts by weight 1,1-bis (t-butylperoxy) cyclohexane 0.075 parts by weight 2- (2H-benzotriazol-2-yl) -p-cresol 0.2 parts by weight bis (2,2,6,6 -Tetramethyl-4-piperidyl) sebacate 0.3 parts by weight Stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate 0.15 parts by weight α-methylstyrene linear dimer 0.075 parts by weight The temperature of the first polymerization machine was 97 ° C.

As a second stream, the following mixture II is continuously added to a 6.2 liter second polymerizer at a feed rate of 1 liter / hour. Mixture II Styrene 89.7% by weight Ethylbenzene 10.3% by weight Total 100 parts by weight Mineral oil 3.1 parts by weight The temperature of the second polymerization machine was 130 to 140 ° C.

These first and second streams are 0.
It has a capacity of 5 liters, the gap between the stirring blade tip and the mixer wall is 5.0 mm, and 15 stages of stirring rods are installed in the axial direction. It is introduced into the stirrer and mixed at a rotation of 200 rpm. Further 6.2
It is sent to the third polymerization machine of liter and the temperature is 112-12.
Polymerized at 0 ° C and stirred to reduce the average particle size of the rubbery material in the pellets. This mixture was then fed to a 6.2 liter fourth polymerizer at a temperature of 140-155.
Polymerized at ° C. The obtained polymer is supplied to an extruder with 2 vents, volatile components are removed under reduced pressure of 230 ° C. and −735 mmHg, a molten strand is drawn from a die, water-cooled, and then finely cut by a cutter, cylindrical pellets. Was continuously produced.

[0030]

Example 4 Mixture I shown below is continuously added as a first stream to a 2.4 liter first polymerizer at a feed rate of 2 liters / hour. Mixture I Polybutadiene rubber 11.5% by weight [Structure of 18% vinyl, 33% cis, 49% trans by infrared spectrophotometer by Morello method] Styrene 70.5% Ethylbenzene 18.0% Total 100 Parts by weight 1,1-bis (t-butylperoxy) cyclohexane 0.075 parts by weight 2- (2H-benzotriazol-2-yl) -p-cresol 0.2 parts by weight bis (2,2,6,6 -Tetramethyl-4-piperidyl) sebacate 0.3 parts by weight Stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate 0.15 parts by weight α-methylstyrene linear dimer 0.075 parts by weight The temperature of the first polymerization machine was 97 ° C. The manufacturing process from the second polymerization machine to the pellet processing is the same as in Example 3.

[0031]

Example 5 Mixture I shown below is continuously added to a 2.4 liter first polymerizer at a feed rate of 2 liter / hour as a first stream. Mixture I Polybutadiene rubber 7.5% by weight [Structure of 18% vinyl, 33% cis, 49% trans] analyzed by an infrared spectrophotometer by the Morello method] Styrene 77.5% by weight Ethylbenzene 15.0% by weight Total 100 Parts by weight 1,1-bis (t-butylperoxy) cyclohexane 0.075 parts by weight 2- (2H-benzotriazol-2-yl) -p-cresol 0.2 parts by weight bis (2,2,6,6 -Tetramethyl-4-piperidyl) sebacate 0.3 parts by weight Stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate 0.15 parts by weight α-methylstyrene linear dimer 0.075 parts by weight The temperature of the first polymerization machine was 97 ° C. The manufacturing process from the second polymerization machine to the pellet processing is the same as in Example 3.

[0032]

Comparative Example 1 Mixture I shown below is continuously added as a first stream to a 2.4 liter first polymerizer at a feed rate of 2 liters / hour. Mixture I Polybutadiene rubber 10.5% by weight [Structure of 18% vinyl, 33% cis and 49% trans as analyzed by an infrared spectrophotometer by the Morello method] Styrene 74.5% Ethylbenzene 15.0% Total 100 Parts by weight 1,1-bis (t-butylperoxy) cyclohexane 0.075 parts by weight 2- (2H-benzotriazol-2-yl) -p-cresol 0.2 parts by weight bis (2,2,6,6 -Tetramethyl-4-piperidyl) sebacate 0.3 parts by weight Stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate 0.15 parts by weight α-methylstyrene linear dimer 0.075 parts by weight The temperature of the first polymerization machine was 97 ° C.

As a second stream, the following mixture II is continuously added to a 6.2 liter second polymerizer at a feed rate of 1 liter / hour. Mixture II Styrene 89.7% by weight Ethylbenzene 10.3% by weight Total 100 parts by weight Mineral oil 3.1 parts by weight The temperature of the second polymerization machine was 130 to 140 ° C. These first stream and second stream, after being joined by a pipe, are sent as they are to a 6.2 liter third polymerization machine and polymerized at a temperature of 112 to 120 ° C. Stirred to reduce the average particle size of the material. Further, this mixture was fed into a 6.2-liter fourth polymerization machine and polymerized at a temperature of 140 to 155 ° C. The obtained polymerized product was supplied to an extruder with 2 vents, and the temperature was 230 ° C. and -735 mmHg.
After removing the volatile components under reduced pressure, pull out the molten strands from the die, cool with water, and cut finely with a cutter.
Cylindrical pellets were produced continuously.

[0034]

Comparative Example 2 Mixture I shown below is continuously added as a first stream to a 2.4 liter first polymerizer at a feed rate of 2 liters / hour. Mixture I Polybutadiene rubber 9.6% by weight [Structure of More than 18% vinyl, cis 33% and trans 49% as analyzed by an infrared spectrophotometer by the Morello method] Styrene 75.4% by weight Ethylbenzene 15.0% by weight Total 100 Parts by weight 1,1-bis (t-butylperoxy) cyclohexane 0.075 parts by weight 2- (2H-benzotriazol-2-yl) -p-cresol 0.2 parts by weight bis (2,2,6,6 -Tetramethyl-4-piperidyl) sebacate 0.3 parts by weight Stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate 0.15 parts by weight α-methylstyrene linear dimer 0.075 parts by weight The temperature of the first polymerization machine was 97 ° C.

As a second stream, the following mixture II is continuously added to a 6.2 liter second polymerizer at a feed rate of 1 liter / hour. Mixture II Styrene 89.7% by weight Ethylbenzene 10.3% by weight Total 100 parts by weight Mineral oil 3.1 parts by weight The temperature of the second polymerization machine was 130 to 140 ° C.

These first and second streams are 0.
It has a capacity of 5 liters, the gap between the tip of the stirring blade and the mixer wall is 25.0 mm, and 15 stages of stirring rods are attached in the axial direction.
A heat transfer tube is introduced into a mixing stirrer between the stirring rods on the machine wall, and is mixed at 100 rpm. Further 6.
It was sent to a 2 liter third polymerization machine and the temperature was 112-1.
Polymerized at 20 ° C and stirred to reduce the average particle size of the rubbery material in the pellets. Furthermore, this mixture is 6.2
It is sent to the fourth polymerization machine of liter and the temperature is 140 ~ 15.
Polymerized at 5 ° C. The obtained polymer is supplied to an extruder with 2 vents, volatile components are removed under reduced pressure of 230 ° C. and −735 mmHg, a molten strand is drawn from a die, water-cooled, and then finely cut by a cutter, cylindrical pellets. Was continuously produced. To the pellets, 0.2 part by weight of a light diffusing agent (a): Takara Mica M-1 (Agrochemitec) was added, and the mixture was uniformly melt-kneaded by a single-screw extruder, and then pelletized again. (Comparative Example 3) In the final pelletizing step of Comparative Example 2, in addition to the light diffusing agent, a sulfur-based chelate compound; (b): 0.2 parts by weight of 2-ethylhexyl β-mercaptopropionate is also added. And pelletized.

[0037]

Comparative Example 4 Mixture I shown below is continuously added as a first stream to a 2.4 liter first polymerizer at a feed rate of 2 liters / hour. Mixture I Polybutadiene rubber 6.0% by weight [Structure of More than 18% vinyl, 33% cis, 49% trans by infrared spectrophotometer by Morello method] Styrene 79.0% by weight Ethylbenzene 15.0% by weight Total 100 Parts by weight 1,1-bis (t-butylperoxy) cyclohexane 0.075 parts by weight 2- (2H-benzotriazol-2-yl) -p-cresol 0.2 parts by weight bis (2,2,6,6 -Tetramethyl-4-piperidyl) sebacate 0.3 parts by weight Stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate 0.15 parts by weight α-methylstyrene linear dimer 0.075 parts by weight The temperature of the first polymerization machine was 97 ° C. The manufacturing process from the second polymerization machine to the pellet processing is the same as in Example 3.

[0038]

Comparative Example 5 Mixture I shown below is continuously added as a first stream to a 2.4 liter first polymerizer at a feed rate of 2 liters / hour. Mixture I Polybutadiene rubber 14.0 wt% [Structure of analysis by infrared spectrophotometer by the Morello method is 18% vinyl, 33% cis, 49% trans] Styrene 68.0 wt% Ethylbenzene 18.0 wt% Total 100 Parts by weight 1,1-bis (t-butylperoxy) cyclohexane 0.075 parts by weight 2- (2H-benzotriazol-2-yl) -p-cresol 0.2 parts by weight bis (2,2,6,6 -Tetramethyl-4-piperidyl) sebacate 0.3 parts by weight Stearyl-β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate 0.15 parts by weight α-methylstyrene linear dimer 0.075 parts by weight The temperature of the first polymerization machine was 97 ° C. The manufacturing process from the second polymerization machine to the pellet processing is the same as in Example 3.
The obtained styrene-based resin is injected into an injection molding machine (IS55EP
N, manufactured by Toshiba Machine Co., Ltd. (cylinder temperature 200
(° C, mold temperature 60 ° C) An evaluation molded product was prepared. The light transmittance, glossiness, and light diffusivity were measured. The results are shown in Table 1.

[0039]

[Table 1] Among Example 2 and Comparative Example 3 containing the sulfur-based chelate compound, Example 2 was good in dark yellowing resistance, but Comparative Example 3 was poor. This is considered to be because in the case of Comparative Example 3, the mica used as the light diffusing agent adsorbs the sulfur-based chelate compound and therefore does not function effectively.

[0040]

EFFECT OF THE INVENTION The molded product for light transmission of the present invention is excellent in light transmission and yet has a light diffusing property in which a light source image is not visible.
In addition, it has a high glossiness and has the function of covering light sources such as lighting equipment (covers, fades, etc.) and light-transmitting industrial parts (keys, buttons, covers, electronic musical instrument keyboards, housings, etc.). It is useful as a light-transmitting molded product.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H042 AA01 AA07 AA21                 4F071 AA22 AA77 AC12 AC19 AF30                       AH12 BB05 BC00                 4J002 BN021 BN061 BN141 BN151                       BN161 EN056 EU077 EU087                       EU176 FD01 FD047 FD056                       FD06 FD07                 4J026 AA06 AA11 AA12 AA13 AA17                       AA67 AA68 AA69 AC01 AC10                       AC11 AC36 BA05 BA06 BA27                       BA31 DB03 DB05 GA08

Claims (2)

[Claims] 1. A rubber-reinforced styrenic resin comprising a rubbery polymer dispersed in a matrix in a matrix of a vinyl aromatic polymer, the particle size of (1) dispersed particles of the rubbery polymer. However, the cumulative volume ratio of dispersed particles having a particle size of 0.2 to 3.0 μm by Coulter Multisizer analysis is 90% or more of the total cumulative volume of all dispersed particles, and (2)
A light-transmitting molded article made of a rubber-reinforced styrene resin, which has a gel content of 15 to 30% by toluene. 2. A light-transmitting rubber-reinforced styrene-based resin according to claim 1, wherein at least one of a benzotriazole-based compound, a hindered amine-based compound and a sulfur-based chelate compound is blended. Molded product.