JP4340421B2 - Rubber-modified styrenic resin composition and molded product thereof - Google Patents

Description

【００４４】
【表２】

【００４５】
【表３】

【００４６】
表３より、比較例１は共重合樹脂Ａ３の重量平均分子量（Ｍｗ）が１３０，０００を超えるため、得られるゴム変性スチレン系樹脂組成物のＭＦＲが小さく成形性に劣る。
比較例２は共重合樹脂Ａ４の重量平均分子量（Ｍｗ）が６０，０００未満のため、得られるゴム変性スチレン系樹脂組成物の衝撃強度が劣る。
比較例３は共重合樹脂Ａ６のオリゴマ−量が２．３％であり、得られるゴム変性スチレン系樹脂組成物のオリゴマー量が２％を超えるためＶＳＰが劣る。
比較例４は共重合樹脂Ａ７の残存モノマー量が３７００ｐｐｍであり、得られるゴム変性スチレン系樹脂組成物の残存モノマー量が３０００ｐｐｍを超えるためＶＳＰが劣る。
比較例５は、グラフト共重合体Ｂ１の配合量が３％のため、得られるゴム変性スチレン系樹脂組成物のゴム含有量が２％未満のため、衝撃強度が劣る。
比較例６は、グラフト共重合体Ｂ１の配合量が４０％のため、得られるゴム変性スチレン系樹脂組成物のゴム含有量が１５％を超えるため、全光線透過率が低下し、ＨａＺｅが大きくなり透明性に劣るものとなり、またＭＦＲが３となり成形及び性衝撃強度が劣る。更にＶＳＰが劣る。
比較例７は、グラフト共重合体Ｂ２の数平均粒子径が０．１μｍ未満のため、得られるゴム変性スチレン系樹脂組成物の衝撃強度が劣る。
比較例８は、グラフト共重合体Ｂ３の数平均ゴム粒子径が０．５μｍを超えるため、全光線透過率が低下し、ＨａＺｅが大きくなり透明性に劣る。
比較例９は、ゴム変性スチレン系樹脂組成物中のオリゴマー量が、０．０５％未満のため、成形不良を生じ成形品外観が劣る。
比較例１０は、ゴム変性スチレン系樹脂組成物中の残存モノマー量が、１００ｐｐｍ未満のため、成形不良を生じ成形品外観が劣る。
【００４７】
【発明の効果】
本発明により、透明性、衝撃強度、及び成形性に優れたゴム変性スチレン系樹脂組成物及びその成形品を提供することができる。特に、成形品としては、衝撃強度が強く、透明性が高く、更に成形サイクルの短縮化が可能な導光板を提供することができる。また、本発明により、製造コストを低減でき、更に外観良好な導光板を容易に得ることができるため、工業上極めて有用である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rubber-modified styrenic resin composition excellent in transparency, impact strength, and moldability, and a molded product thereof. In particular, the molded article relates to a light guide plate used for OA equipment such as a personal computer, a liquid crystal display device used for various monitors of image signals, and the like.
[0002]
[Prior art]
Recently, a light guide for a backlight of a liquid crystal display device provided with an illumination lamp has been used. Two types of backlights are commonly used: a so-called direct type in which a light guide is sandwiched between a light source and a liquid crystal unit, and an edge light type in which the light source is attached to the edge of the light guide plate. An edge light system in which a light source is disposed on a side surface of a light guide and light incident on the light guide from the light source is scattered on the bottom surface facing the light emitting surface is the mainstream. Many such techniques have been disclosed so far.
[0003]
For example, in Japanese Utility Model Laid-Open Nos. 61-157986, 62-87315, 63-43186, and 5-47922, the amount of light scattering increases as the distance from the light source increases. A technique of using a light guide provided with unevenness is disclosed. In JP-A-2-165504, etc., a groove whose shape is devised so that light from the light source can be efficiently emitted to the observation side is formed on the bottom surface portion facing the light emitting surface of the light guide, and the groove is further away from the light source. A technique for increasing the amount of light scattering by widening the distance and making deep grooves is disclosed.
Furthermore, in Japanese Utility Model Laid-Open No. 60-94605, a groove shape for scattering light is formed on the bottom surface portion facing the light emitting surface of the light guide, and the thickness of the light guide is increased as the distance from the light source increases. There is disclosed a technique for achieving a reduction in thickness and weight and an increase in brightness by reducing the wedge shape.
[0004]
[Problems to be solved by the invention]
As described above, various techniques related to the light guide are disclosed, but as the resin used for the light guide plate, polystyrene and acrylic resin, among which acrylic resin was mainly studied. There is a problem that the hygroscopicity is high, and therefore the size of the light guide plate is easily changed, and the recent demand for ultra-lightweight OA equipment cannot be sufficiently met.
In addition, when an acrylic resin is injection-molded, since the viscosity at the time of melting is high, the injection time becomes long, the productivity is inferior, and there is a problem in economy. In order to reduce the melt viscosity and shorten the injection time, when the molding temperature is increased, the acrylic resin is decomposed, silver streaks are generated on the surface of the molded product, and there is a problem that the commercial value is lowered.
[0005]
As a result of various studies to solve the above problems, the present inventors have found that a specific proportion of styrene monomer, (meth) acrylic acid ester monomer, and vinyl copolymerizable with these monomers. Styrene- (meth) acrylic ester copolymer resin having a specific range of weight average molecular weight (Mw), diene rubber-like elastic body, styrene monomer, (meth) acrylic ester A rubber-modified styrenic resin composition comprising as a main component a monomer and a graft copolymer having a specific rubber particle diameter composed of a vinyl monomer copolymerizable with these monomers, Resin in which the amount of residual monomer and oligomer in the rubber-modified styrene resin composition is controlled within a specific range has low hygroscopicity, high strength, high transparency, light weight, and can shorten the molding cycle. Molding And we have completed the present invention obtained a finding that is particularly suitable in the light guide plate.
[0006]
[Means for Solving the Problems]
That is, the present invention comprises (1) a styrene monomer and a (meth) acrylic ester monomer, and is any of a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and a bulk-suspension polymerization method. Styrene- (meth) acrylic acid ester copolymers produced by such polymerization methods, diene rubber-like elastic bodies, styrene monomers, (meth) acrylic acid ester monomers, and single monomers thereof. A rubber-modified styrenic resin composition comprising a vinyl monomer copolymerizable with a monomer and obtained by melt-mixing with a graft copolymer produced by an emulsion polymerization method, The composition has a weight-average molecular weight (Mw) of THF (tetrahydrofuran) solubles of 60,000 to 130,000, 20 to 80% by mass of the styrene monomer unit of the solubles, (meta) Ak Le ester monomer units 80 to 20 mass%, and 0 to 10 wt% other vinyl-based monomer unit, 2 to 15% content of the rubber, number-average rubber particle diameter Is a rubber-modified styrenic resin composition for a light guide plate , wherein the residual monomer amount is 100 to 3000 ppm, and the oligomer amount is 0.05 to 2%, 2) The rubber-modified styrene resin composition for a light guide plate according to (1), wherein the content of alkaline earth metal is 10 ppm or less, and the rubber-modified styrene according to (3) (1) or (2) It is a light-guide plate formed by injection-molding a resin composition.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
Examples of the styrene monomer used in the present invention include styrene, α-methylstyrene, p-methylstyrene, o-methylstyrene, m-methylstyrene, ethylstyrene, pt-butylstyrene, and the like. Is preferably styrene. These styrenic monomers may be used alone or in combination of two or more.
[0008]
As the (meth) acrylic acid ester monomer used in the present invention, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate methacrylate ester, methyl acrylate Acrylate, ethyl acrylate, n-butyl acrylate, 2-methylhexyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, etc., preferably methyl (meth) acrylate or n-butyl acrylate, particularly preferably methyl (Meth) acrylate. These (meth) acrylic acid ester monomers may be used alone or in combination of two or more.
[0009]
Furthermore, examples of the vinyl monomer copolymerizable with these monomers as required include acrylic acid, methacrylic acid, acrylonitrile, methacrylonitrile, N-phenylmaleimide, N-cyclohexylmaleimide and the like.
[0010]
Examples of the diene rubber-like elastic body used in the present invention include polybutadiene, styrene-butadiene block copolymer, and styrene-butadiene random copolymer.
[0011]
The THF (tetrahydrofuran) soluble component referred to in the present invention includes all other components soluble in THF, the main component of which is a styrene- (meth) acrylic ester copolymer.
[0012]
Further, the THF-insoluble component is mainly composed of a graft copolymer, but all other components insoluble in THF are included.
[0013]
In addition, the rubber-modified styrene resin composition of the present invention has good transparency that the difference in refractive index between the styrene- (meth) acrylate copolymer and the graft copolymer is approximate. Therefore, it is preferable.
[0014]
The ratio of each monomer constituting the styrene- (meth) acrylic acid ester copolymer is not particularly limited, but preferably 20 to 80% by mass of styrene monomer units (meta) ) 20 to 80% by mass of acrylic acid ester monomer units, and 0 to 10% by mass of vinyl monomer units copolymerizable with these monomers used as necessary, The monomer ratio is more preferably such that the difference in refractive index from the graft copolymer is approximate.
[0015]
Further, the amount of the rubber-like elastic body and each monomer constituting the graft copolymer is not particularly limited, but preferably 30 to 80 parts by mass of the rubber-like elastic body is a styrene monomer unit. 20 to 80% by mass, (meth) acrylic acid ester monomer unit 20 to 80% by mass, and vinyl monomer unit 0 to 10 mass copolymerizable with these monomers used as necessary % Styrene- (meth) acrylic acid ester copolymer 20-70 parts by mass of graft copolymer, and styrene- (meth) acrylic acid ester copolymer grafted within the range More preferably, the monomer ratio is such that the difference in refractive index between the rubbery elastic body and the rubber-like elastic body is approximate.
[0016]
The rubber-modified styrene resin composition used in the present invention preferably has a weight-average molecular weight (Mw) of THF (tetrahydrofuran) soluble component of 60,000 to 130,000. If the weight average molecular weight (Mw) is less than 60,000, the impact strength decreases, which is not preferable. If it exceeds 130,000, the flow decreases and the molding cycle becomes longer.
[0017]
The rubber-modified styrene resin composition used in the present invention has 20 to 80% by mass of styrene monomer units soluble in THF (tetrahydrofuran), and 80 to 20 (meth) acrylate monomer units. It is preferable that the mass% and other vinyl monomer units are 0 to 10 mass%. Outside this range, the transparency is lowered, which is not preferable.
[0018]
The rubber amount of the rubber-modified styrenic resin composition used in the present invention is preferably 2 to 15%. If the amount of rubber is less than 2%, the impact strength decreases, and if it exceeds 15%, the transparency decreases, which is not preferable.
[0019]
The rubber-modified styrene resin composition used in the present invention preferably has a rubber particle size of 0.1 to 0.5 μm. If the rubber particle diameter is less than 0.1 μm, the impact strength decreases, and if it exceeds 0.5 μm, the transparency decreases, which is not preferable.
[0020]
The residual monomer amount of the rubber-modified styrene resin composition used in the present invention is preferably 100 to 3000 ppm. If the residual monomer amount is less than 100 ppm, molding defects occur, and if it exceeds 3000 ppm, molding defects and heat resistance decrease are undesirable.
[0021]
The oligomer amount of the rubber-modified styrene resin composition used in the present invention is preferably 0.05 to 2%. If the amount of the oligomer is less than 0.05%, molding failure occurs, and if it exceeds 2%, the heat resistance decreases, which is not preferable.
In the present invention, the amount of oligomer is determined by evaporating and drying the extract obtained by refluxing n-hexane for 6 hours or more with an extractor such as Soxhlet using a freeze-ground sample (Xg). To obtain an extract (referred to as Yg), which is calculated by the following equation.
Oligomer amount (%) = Y / X × 100
From the above, it can be said that the oligomer amount (%) is equivalent to the n-hexane extract (%).
[0022]
The styrene- (meth) acrylic acid ester copolymer used in the present invention can be subjected to suspension polymerization using an alkaline earth metal salt as a dispersant, but remains in the rubber-modified styrene resin composition. In order to further improve the transparency of the similar metal, it is preferably 10 ppm or less.
[0023]
The rubber-modified styrenic resin composition of the present invention can be produced by known techniques such as bulk polymerization, solution polymerization, suspension polymerization, bulk-suspension polymerization, and emulsion polymerization.
In addition, any of a batch polymerization method and a continuous polymerization method can be used.
[0024]
Preferably, the graft copolymer-containing resin is produced by an emulsion polymerization method, and the styrene- (meth) acrylic ester copolymer is produced by a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and a bulk-suspension weight. It is produced by melt polymerization of the graft copolymer-containing resin and the styrene- (meth) acrylic acid ester copolymer, and is produced by any polymerization method. It is possible to obtain a rubber-modified styrenic resin composition that is excellent in properties and in particular can shorten the molding cycle during injection molding.
[0025]
The rubber-modified styrenic resin composition of the present invention is added with known weathering agents, lubricants, plasticizers, colorants, antistatic agents, mineral oils and other additives, and the performance of the rubber-modified styrene-based resin composition of the present invention. You may mix | blend in the range which does not impair.
[0026]
In the light guide plate of the present invention, other components such as cross-linked acrylic particles, cross-linked styrene particles and other organic light diffusing agents, barium sulfate, calcium carbonate, titanium oxide and the like are included within the scope of the present invention. A system light diffusing agent or the like can be blended.
[0027]
As a method for obtaining the light guide plate of the present invention, a molded body having an arbitrary shape can be obtained by filling a mold or a mold with a resin with an injection molding machine or the like.
【Example】
Hereinafter, although detailed content is demonstrated using an Example, this invention is not limited to a following example.
[0028]
Evaluation Method (1) MFR Measured according to JIS K-6874 at 200 ° C. and 5 kg load.
(2) Measured with a 5 kg load according to VSP JIS K-7206.
(4) Total light transmittance It measured according to ASTM D1003.
(5) Measured according to HaZe ASTM D1003.
(6) Impact strength A light guide plate having a molding temperature of 270 ° C. and a mold temperature of 50 ° C., having a length of 292.5 mm, a width of 220 mm, and a thickness of 2 mm was formed by using an electric injection molding machine J350ELIII. A weight tip 5R, a weight diameter of 14 mmφ, and a weight of 50 gf was dropped on the surface of the optical plate, and expressed as breaking energy at a breaking height of 50%.
A material having a fracture energy of 80 kg / cm or more was determined as a preferred impact strength.
(7) Formability Electric light injection molding machine J350ELIII manufactured by Nippon Steel Works, a light guide plate with a molding temperature of 270 ° C and a mold temperature of 50 ° C of length 292.5mm, width 220mm, and thickness 2mm was obtained per hour. The number that can be expressed. What was obtained 60 pieces / Hr or more was made into the preferable moldability.
[0029]
Copolymer resin A1 production capacity 250 liters of autoclave with a capacity of 250 liters, 0.5 g of sodium dodecylbenzenesulfonate, 250 g of tribasic calcium phosphate, 40 kg of styrene, 60 kg of methyl methacrylate are added to 100 kg of pure water. 100 g of oxyisobutyrate and 420 g of t-dodecyl mercaptan were added, and the mixed solution was dispersed with stirring at a rotational speed of 150 rpm. The mixture was subjected to heat polymerization at a temperature of 100 ° C. for 8 hours and at 130 ° C. for 2.5 hours. After completion of the reaction, washing, dehydration and drying were performed to obtain a bead-shaped copolymer resin. This was designated as copolymer resin A1.
[0030]
Copolymer resin A2 production capacity In a 250 liter autoclave, 100 g of pure water was charged with 0.5 g of sodium dodecylbenzenesulfonate, 250 g of tricalcium phosphate, 40 kg of styrene, and 60 kg of methyl methacrylate. 100 g of oxyisobutyrate and 180 g of t-dodecyl mercaptan were added, and the mixed solution was dispersed with stirring at a rotational speed of 150 rpm. The mixture was subjected to heat polymerization at a temperature of 100 ° C. for 8 hours and at 130 ° C. for 2.5 hours. After completion of the reaction, washing, dehydration and drying were performed to obtain a bead-shaped copolymer resin. This was designated as copolymer resin A2.
[0031]
Copolymer Resin A3 Production Capacity: 250 liters of autoclave, 100 g of pure water, 0.5 g of sodium dodecylbenzenesulfonate, 250 g of tribasic calcium phosphate, 40 kg of styrene, 60 kg of methyl methacrylate are added as a polymerization initiator. 100 g of oxyisobutyrate and 220 g of t-dodecyl mercaptan were added, and the mixed solution was dispersed with stirring at a rotational speed of 150 rpm. The mixture was subjected to heat polymerization at a temperature of 100 ° C. for 8 hours and at 130 ° C. for 2.5 hours. After completion of the reaction, washing, dehydration and drying were performed to obtain a bead-shaped copolymer resin. This was designated as copolymer resin A3.
[0032]
Copolymer resin A4 production capacity: 250 liters of autoclave, 100 g of pure water, 0.5 g of sodium dodecylbenzenesulfonate, 250 g of tribasic calcium phosphate, 40 kg of styrene, 60 kg of methyl methacrylate are added as a polymerization initiator. 100 g of oxyisobutyrate and 840 g of t-dodecyl mercaptan were added, and the mixed solution was dispersed with stirring at a rotational speed of 150 rpm. The mixture was subjected to heat polymerization at a temperature of 100 ° C. for 8 hours and at 130 ° C. for 2.5 hours. After completion of the reaction, washing, dehydration and drying were performed to obtain a bead-shaped copolymer resin. This was designated as copolymer resin A4.
[0033]
Production volume of copolymer resin A5: about 15 liters of fully mixed reactor, about 40 liters of tower-type plug flow reactor, first devolatilizer tank with preheater, static mixer, preheater Two devolatilization tanks were connected in series. For a monomer solution composed of 40 parts by mass of styrene and 60 parts by mass of methyl methacrylate, 15 parts by mass of ethylbenzene, 0.03 parts by mass of t-butylperoxyisopropyl monocarbonate (1 hour half-life temperature: 118 ° C.), 0.1 parts by mass of octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate (antioxidant) and 0.1 parts by mass of t-dodecyl mercaptan were mixed to obtain a raw material solution. This raw material solution was supplied to a fully mixed reactor controlled at a temperature of 120 ° C. at 6.9 kg / hour. Further, this polymerization solution was introduced into a column type plug flow reactor adjusted so as to have a gradient of 120 ° C. to 150 ° C. in the flow direction. The polymerization solution was introduced into a first devolatilization tank whose pressure was reduced to 10.6 kPa while heating with a preheater, and a part of the unreacted monomer was removed at a temperature in the first devolatilization tank of 230 ° C. Further, while extracting this liquid with a gear pump, 18 g of water per hour (0.3 parts by mass with respect to a total of 100 parts by mass of the monomer) was added to and mixed with the static mixer, and then heated with a preheater. It introduce | transduced into the 2nd devolatilization tank pressure-reduced to 0.3 kPa, and the unreacted monomer was removed at the temperature in the 2nd devolatilization tank at 230 degreeC. This was extracted with a gear pump and extruded into a strand shape to obtain a pellet-shaped copolymer resin. This was designated as copolymer resin A5.
[0034]
Production of copolymer resin A6 The procedure was the same as that for copolymer resin A5 except that t-butylperoxyisopropyl monocarbonate was not added to the raw material solution. The obtained copolymer resin was designated as A6.
[0035]
Copolymer resin A7 production capacity: 250 liters of autoclave, 100 g of pure water, 0.5 g of sodium dodecylbenzenesulfonate, 250 g of tribasic calcium phosphate, 40 kg of styrene, 60 kg of methyl methacrylate are added as a polymerization initiator. 100 g of oxyisobutyrate and 420 g of t-dodecyl mercaptan were added, and the mixed solution was dispersed with stirring at a rotational speed of 150 rpm. The mixture was subjected to heat polymerization at a temperature of 100 ° C. for 8 hours and at 120 ° C. for 2.5 hours. After completion of the reaction, washing, dehydration and drying were performed to obtain a bead-shaped copolymer resin. This was designated as copolymer resin A7.
[0036]
Production of Copolymer Resin A8 Copolymer resin A1 was refluxed with petroleum ether at 80 ° C. for 4 hours, and the oligomer was extracted and removed to obtain copolymer A8.
[0037]
Copolymer A9 Production capacity of 250 liters in an autoclave with a capacity of 250 liters, 0.5 g of sodium dodecylbenzenesulfonate, 250 g of tricalcium phosphate, 40 kg of styrene and 60 kg of methyl methacrylate are added to 100 kg of pure water. 100 g of oxyisobutyrate and 420 g of t-dodecyl mercaptan were added, and the mixed solution was dispersed with stirring at a rotational speed of 150 rpm. The mixture was subjected to heat polymerization at a temperature of 100 ° C. for 8 hours and at 130 ° C. for 10 hours. After completion of the reaction, washing, dehydration and drying were performed to obtain a bead-shaped copolymer resin. This was designated as copolymer resin A9.
[0038]
Production of graft copolymer B1 In an autoclave equipped with a stirrer, 49 parts of butadiene, 16 parts of styrene, 150 parts of pure water, 0.5 part of potassium oleate, 0.13 part of t-butyl hydroperoxide, 0.03 part of Rongalite, First, 0.002 part of ferrous sulfate, 0.003 part of ethylenediaminetetraacetic acid sodium salt, 0.1 part of sodium pyrophosphate, and 1.0 part of t-dodecyl mercaptan were charged and polymerized at a temperature of 45 ° C. for 17 hours. The number average particle diameter of the obtained styrene-butadiene rubber latex was 0.08 μm. The latex was stabilized by adding 0.005 part of sodium sulfosuccinate. The latex particles were agglomerated and enlarged by adding an aqueous hydrogen chloride solution to the latex under stirring to obtain a rubber latex having a number average particle size of 0.2 μm. To this latex, 16 parts of styrene, 17 parts of MMA, 2 parts of n-butyl acrylate, 0.04 part of divinylbenzene and 0.08 part of t-butyl hydroperoxide were added and polymerized at a temperature of 60 ° C. for 6 hours. After adding 0.5 parts of t-butylphenol and 0.5 parts of dilauryl thiopropionate to this latex, the copolymer is precipitated with hydrochloric acid, neutralized and washed, dehydrated and dried to obtain a powdery graft copolymer. Combined B1 was obtained. The amount of rubber component of the graft copolymer B1 was 48.0%.
[0039]
By changing only the agglomeration conditions of the rubber latex in the same manner as in the production of the graft copolymer B1, the graft copolymer B2 having dispersed particles having a number average particle diameter of 0.08 μm and a dispersed particle having 0.6 μm Graft copolymer B3 having
[0040]
Production of Graft Copolymer B4 Graft copolymer B1 was refluxed with petroleum ether at 80 ° C. for 4 hours, and the oligomer was extracted and removed to obtain graft copolymer B4.
[0041]
Production of graft copolymer B5 In an autoclave equipped with a stirrer, 49 parts of butadiene, 16 parts of styrene, 150 parts of pure water, 0.5 part of potassium oleate, 0.13 part of t-butyl hydroperoxide, 0.03 part of Rongalite, First, 0.002 part of ferrous sulfate, 0.003 part of ethylenediaminetetraacetic acid sodium salt, 0.1 part of sodium pyrophosphate, and 1.0 part of t-dodecyl mercaptan were charged and polymerized at a temperature of 45 ° C. for 17 hours. The number average particle diameter of the obtained styrene-butadiene rubber latex was 0.08 μm. The latex was stabilized by adding 0.005 part of sodium sulfosuccinate. The latex particles were agglomerated and enlarged by adding an aqueous hydrogen chloride solution to the latex under stirring to obtain a rubber latex having a number average particle size of 0.2 μm. To this latex, 16 parts of styrene, 17 parts of MMA, 2 parts of n-butyl acrylate, 0.04 part of divinylbenzene and 0.08 part of t-butyl hydroperoxide are added, 6 hours at a temperature of 60 ° C. and 6 hours at a temperature of 90 ° C. Polymerized for hours. After adding 0.5 parts of t-butylphenol and 0.5 parts of dilauryl thiopropionate to this latex, the copolymer is precipitated with hydrochloric acid, neutralized and washed, dehydrated and dried to obtain a powdery graft copolymer. Combined B5 was obtained. The amount of rubber component of this graft copolymer B5 was 48.0%.
[0042]
Examples 1-3, Comparative Examples 1-10
Copolymers A1 to A9 and graft copolymers B1 to B5 obtained above were pelletized at a temperature of 200 ° C. using a twin-screw press TEM35B manufactured by Toshiba Machine Co., Ltd., with the formulation shown in Table 2. Next, the obtained pellets were subjected to a light guide plate of 292.5 mm length, 220 mm width, and 2 mm thickness at a molding temperature of 270 ° C. by J350ELIII manufactured by Nippon Steel Works, an electric injection molding machine. Subsequently, the characteristic evaluation of the obtained light-guide plate was performed.
The results are shown in Table 3.
[0043]
[Table 1]

[0044]
[Table 2]

[0045]
[Table 3]

[0046]
From Table 3, since the weight average molecular weight (Mw) of copolymerization resin A3 exceeds 130,000 from Comparative Example 1, MFR of the rubber-modified styrene resin composition obtained is small, and it is inferior to moldability.
In Comparative Example 2, since the copolymer resin A4 has a weight average molecular weight (Mw) of less than 60,000, the resulting rubber-modified styrenic resin composition is inferior in impact strength.
In Comparative Example 3, the amount of oligomer of copolymer resin A6 is 2.3%, and the amount of oligomer of the resulting rubber-modified styrenic resin composition exceeds 2%, so VSP is inferior.
In Comparative Example 4, the amount of residual monomer in copolymer resin A7 is 3700 ppm, and the amount of residual monomer in the resulting rubber-modified styrenic resin composition exceeds 3000 ppm, resulting in poor VSP.
In Comparative Example 5, since the blending amount of the graft copolymer B1 is 3%, the rubber content of the obtained rubber-modified styrenic resin composition is less than 2%, so that the impact strength is inferior.
In Comparative Example 6, since the blending amount of the graft copolymer B1 is 40%, the rubber content of the resulting rubber-modified styrenic resin composition exceeds 15%, the total light transmittance is decreased, and the HaZe is large. Thus, the transparency is inferior, and the MFR is 3, so that the molding and property impact strength are inferior. Furthermore, VSP is inferior.
In Comparative Example 7, since the number average particle diameter of the graft copolymer B2 is less than 0.1 μm, the impact strength of the obtained rubber-modified styrene resin composition is inferior.
In Comparative Example 8, since the number average rubber particle diameter of the graft copolymer B3 exceeds 0.5 μm, the total light transmittance is lowered, the HaZe is increased, and the transparency is inferior.
In Comparative Example 9, the amount of oligomer in the rubber-modified styrenic resin composition is less than 0.05%, resulting in poor molding and poor molded product appearance.
In Comparative Example 10, since the amount of residual monomer in the rubber-modified styrene resin composition is less than 100 ppm, molding failure occurs and the appearance of the molded product is inferior.
[0047]
【The invention's effect】
According to the present invention, it is possible to provide a rubber-modified styrenic resin composition excellent in transparency, impact strength, and moldability, and a molded product thereof. In particular, as a molded product, a light guide plate having high impact strength, high transparency, and capable of shortening the molding cycle can be provided. Further, according to the present invention, the manufacturing cost can be reduced, and a light guide plate having a better appearance can be easily obtained, which is extremely useful industrially.

Claims (3)

Styrene made of a styrene monomer and a (meth) acrylic acid ester monomer and produced by any one of a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and a bulk-suspension polymerization method -(Meth) acrylic acid ester copolymer,
Diene rubber-styrene monomer and (meth) acrylic acid ester monomer or Rannahli, rubber-modified styrene obtainable by a manufactured graft copolymer is melt-mixed by an emulsion polymerization method A resin composition comprising:
The rubber-modified styrenic resin composition has a weight average molecular weight (Mw) soluble in THF (tetrahydrofuran) of 60,000 to 130,000,
Styrene monomer units is 20 to 80% by weight of the movable matter, (meth) acrylic acid ester monomer units is 80 to 20 wt%,
The rubber content is 2-15%,
The number average rubber particle size is 0.1 to 0.5 μm,
The residual monomer amount is 100-3000 ppm,
Furthermore, the amount of oligomer is 0.05 to 2%, a rubber-modified styrene resin composition for a light guide plate.   The rubber-modified styrenic resin composition for a light guide plate according to claim 1, wherein the alkaline earth metal content is 10 ppm or less.   A light guide plate obtained by injection molding the rubber-modified styrene resin composition for a light guide plate according to claim 1 or 2.