JP2005264003A - Rubber-modified copolymer resin and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a rubber-modified copolymer resin good in hue, slight in residual monomer after polymerized, good in balance between transparency and impact resistance, and good in recyclability, and to provide a method for producing the copolymer resin. <P>SOLUTION: The rubber-modified copolymer resin is obtained by copolymerization between a styrene-based monomer and a (meth)acrylic ester monomer in the presence of a rubbery polymer. This copolymer resin is ≥85% in total light transmittance in a thickness of 2 mm determined in accordance with JIS K7105. This copolymer resin has also the following characteristics: the volume-average size (dv) of rubber particles dispersed in the resin is 0.4-1.6μm, the weight-average molecular weight (Mw) of the matrix is 90,000-180,000, toluene insolubles is greater than 15 mass% but not greater than 30 mass%, swelling index is ≥10, and the total amount of the styrene-based monomer and the (meth)acrylic ester monomer left in the resin is ≤700 ppm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a rubber-modified copolymer resin having a good hue, a small residual monomer remaining after polymerization, a good balance between transparency and impact resistance, and a good recyclability, and a production method.

Conventionally, for transparent rubber-modified copolymer resins obtained by copolymerizing styrene monomers and (meth) acrylate monomers in the presence of rubber-like polymers, transparency and impact resistance In order to achieve this balance, various studies have been made, and a technique for copolymerizing two or more (meth) acrylic acid esters (see, for example, Patent Document 1) or a specific rubbery polymer is used. A technique (for example, refer to Patent Document 2) for setting a toluene insoluble content, a swelling index, and the like within a specific range is disclosed.
JP-A-52-124095 (page 1-7) However, these have a good balance between transparency and impact resistance in one-way applications, but they are recycled in the recent trend of recycling applications. Occasionally, there was a problem that the odor was strong or the physical properties after recycling were greatly reduced. To solve this problem, there is a technique to improve by adding a large amount of stabilizers such as antioxidants at the time of recycling. However, since it leads to deterioration of hue and cost increase, a transparent rubber-modified copolymer resin with good recyclability is required. It is desired. In addition, if the residual volatile content in the resin is large, it may cause yellowing during molding and problems that cause burns. In recent years, it has good appearance from a design orientation and low residual volatility from a health orientation. Differentiation is required.

  The present invention provides a rubber-modified copolymer resin having a good hue, a small residual monomer remaining after polymerization, a good balance between transparency and impact resistance, and a good recyclability, and a production method. Objective.

As a result of intensive studies to solve such problems, the present inventors obtained a copolymer of a styrene monomer and a (meth) acrylate monomer in the presence of a rubbery polymer. , A transparent rubber-modified copolymer resin having a total light transmittance of 85% or more at a thickness of 2 mm measured based on JIS K7105, and the volume average particle diameter (dv) of rubber particles dispersed in the resin is 0.4 to 1.6 μm, weight average molecular weight (Mw) of the matrix is 90,000 to 180,000, toluene insoluble content exceeds 15% by mass and 30% by mass or less, swelling index is 10 or more, and remains in the resin A rubber-modified copolymer resin characterized by having a total of 700 ppm or less of a styrene monomer and a (meth) acrylic acid ester monomer has a good hue and a small amount of residual monomer after polymerization, Transparency and impact resistance Balance is good, found that excellent recyclability, has led to the present invention.
The transparent rubber-modified copolymer resin according to claim 1, wherein the ratio of the rubber particles other than the onion structure is 50% or more, and further, the balance between transparency and impact resistance is good and the recyclability is improved. As a result, the present invention was found.

  Furthermore, the production method characterized by devolatilization at a resin temperature of 230 to 260 ° C. and a pressure of 6 kPa or less in the presence of a hindered phenol-based antioxidant, has a good hue and good residual amount after polymerization. The present inventors have found that a rubber-modified copolymer resin having a small remaining amount of body, a good balance between transparency and impact resistance, and excellent recyclability can be obtained.

  The rubber-modified copolymer resin of the present invention has a good hue, a small amount of residual monomer after polymerization, a good balance between transparency and impact resistance, and good recyclability. It is useful for various applications including materials and sheets. Moreover, the rubber-modified copolymer resin can be efficiently produced by the production method of the present invention.

The present invention is described in detail below.
Examples of the styrenic monomer used in the present invention include styrene, α-methylstyrene, p-methylstyrene, pt-butylstyrene, and the like, and styrene is preferable. These styrene monomers may be used alone or in combination of two or more.

  Examples of the (meth) acrylic acid ester monomer used in the present invention include methyl methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-methylhexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, and the like. It is preferable to use two or more (meth) acrylic acid ester monomers in combination. In addition, a (meth) acrylic acid ester monomer having a glass transition temperature (Tg) of 100 ° C. or higher when homopolymerized and a (meta) glass transition temperature (Tg) of 0 ° C. or lower when homopolymerized. It is more preferable to use an acrylic ester monomer in combination. More preferable examples include methyl methacrylate (homopolymer Tg = 105 ° C.) and n-butyl acrylate (homopolymer Tg = −49 ° C.).

  In the present invention, a copolymerizable monomer other than a styrene monomer or a (meth) acrylic acid ester monomer, such as acrylonitrile, maleic anhydride, (meth) acrylic acid, N-phenylmaleimide, etc. If it is less than 50 mass parts with respect to a total of 100 mass parts of a system monomer and a (meth) acrylic acid ester monomer, it can be contained.

  The ratio of the styrene monomer and the (meth) acrylate monomer is preferably 5 to 95 parts by mass of the styrene monomer and 95 to 5 parts by mass of the (meth) acrylate monomer, Preferably, they are 10-90 mass parts of styrene-type monomers, and 90-10 mass parts of (meth) acrylic acid ester-type monomers. However, the total of the styrene monomer and the (meth) acrylic acid ester monomer is 100 parts by mass. When the styrene monomer and the (meth) acrylic acid ester monomer are out of the range, the transparency may be inferior.

Examples of the rubbery polymer used in the present invention include polybutadiene, styrene-butadiene rubber, styrene-butadiene block rubber, partially hydrogenated polybutadiene, partially hydrogenated styrene-butadiene rubber, and partially hydrogenated styrene-butadiene block rubber. However, styrene-butadiene rubber and styrene-butadiene block rubber having a styrene content of 32 to 45% by mass are preferable. Moreover, the 5 mass% styrene solution viscosity in 25 degreeC of temperature becomes like this. Preferably it is 15-60 mPa * s, More preferably, it is 20-40 mPa * s. The proportion of 1,2-vinyl bonds in the unsaturated bonds based on butadiene is preferably 16 mol% or less, more preferably 10 to 14 mol%. When a rubbery polymer having a 1,2-vinyl bond ratio exceeding 16 mol% is used, it may be inferior in recyclability.
A polymer other than a rubber-like polymer such as styrene-butadiene-styrene resin can be contained as long as it is less than 50 parts by mass with respect to 100 parts by mass of the rubber-like polymer.
The ratio of the rubber-like polymer is preferably 0.1 to 30 parts by mass, more preferably 3 to 15 parts by mass with respect to 100 parts by mass in total of the styrene monomer and the (meth) acrylic acid ester monomer. It is. When the rubbery polymer is out of this range, the balance between transparency and impact resistance may be inferior.

  The rubber-modified copolymer resin is obtained by polymerizing a styrene monomer and a (meth) acrylic acid ester monomer in the presence of a rubbery polymer. The rubbery polymer is dissolved in a styrene monomer or a (meth) acrylic acid ester monomer and then used for polymerization.

The polymerization mode is preferably a continuous polymerization mode from the viewpoints of economy and the like, and from the viewpoint of quality such as not using a suspension stabilizer used in batch suspension polymerization that may cause coloring. Although there is no restriction | limiting in particular as a reaction apparatus, It is preferable to use combining a complete mixing type reactor, a column type plug flow type reactor, a devolatilization tank, etc.
In the polymerization, a solvent such as ethylbenzene or toluene is preferably 25 parts by mass or less, more preferably 5 to 20 parts by mass with respect to 100 parts by mass in total of the styrene monomer and the (meth) acrylic acid ester monomer. Part can be used. Use of a solvent may lower the viscosity during polymerization and improve the polymerization controllability.
The polymerization temperature is preferably 80 to 170 ° C, more preferably 100 to 160 ° C.

t-butylperoxybenzoate, t-butylperoxy-2-ethylhexanoate, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t- Butylperoxy) -cyclohexane, 2,2-bis (4,4-di-butylperoxycyclohexyl) propane, t-butylperoxyisopropyl monocarbonate, di-t-butyl peroxide, dicumyl peroxide, ethyl- Known polymerization initiators such as 3,3-di- (t-butylperoxy) butyrate can be used, and two or more kinds having different half-life temperatures are more preferably used from the viewpoint of impact resistance.
The addition amount of the polymerization initiator is preferably 0.005 to 5 parts by mass, more preferably 0.01 to 1 part by mass with respect to 100 parts by mass in total of the styrene monomer and the (meth) acrylic acid ester monomer. Part. If it is outside this range, the balance between transparency and impact resistance and recyclability may be inferior.

It is preferable to add a known molecular weight regulator such as 4-methyl-2,4-diphenylpentene-1, t-dodecyl mercaptan, n-dodecyl mercaptan during the polymerization.
The addition amount of the molecular weight modifier is preferably 0.005 to 5 parts by mass, more preferably 0.01 to 1 part by mass with respect to 100 parts by mass in total of the styrene monomer and the (meth) acrylic acid ester monomer. Part. If it is outside this range, the purpose may not be achieved.

During polymerization, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], It is preferable to add a hindered phenolic antioxidant such as ethylenebis (oxyethylene) bis [3- (5-t-butyl-4-hydroxy-m-tolyl) propionate).
The addition amount of the antioxidant is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 1 part by mass with respect to a total of 100 parts by mass of the styrene monomer and the (meth) acrylate monomer. Part. When hindered phenolic antioxidants are not added during polymerization, when antioxidants other than hindered phenolic antioxidants are used, and when more than 1 part by weight of hindered phenolic antioxidants are added May be unfavorable due to low recyclability.

  After the polymerization, devolatilization is carried out using a known equipment such as a devolatilization tank or an extruder for the purpose of removing unreacted monomers and solvents. At this time, the devolatilization is preferably performed at a resin temperature of 230 to 260 ° C. and a pressure of 6 kPa or less, and more preferably at a resin temperature of 240 to 250 ° C. and a pressure of 2 kPa or less. If it is outside this range, the balance between transparency and impact resistance and recyclability may be inferior.

Rubber particles are dispersed in the rubber-modified copolymer resin. The volume average particle diameter (dv) of the rubber particles is 0.4 to 1.6 μm, preferably 0.4 to 1.3 μm, and more preferably 0.5 to 1.2 μm. If it is outside this range, the balance between transparency and impact resistance and recyclability may be inferior.
The volume average particle diameter (dv) is obtained by measuring the particle diameter Di (equivalent circle diameter) of about 3000 rubber particles in the photograph from an ultra-thin section transmission electron micrograph of the resin, The average particle diameter is determined.

ゴム粒子はゴム変性共重合樹脂を重合する際、重合の進行に伴い形成する。体積平均粒子径（ｄｖ）の制御は重合時の撹拌数、重合開始剤や分子量調整剤の添加量、異なる粒子径を有するゴム変性共重合樹脂の混合等で実施できる。

The rubber particles are formed as the polymerization progresses when the rubber-modified copolymer resin is polymerized. The volume average particle diameter (dv) can be controlled by the number of stirring during polymerization, the addition amount of a polymerization initiator or a molecular weight modifier, mixing of rubber-modified copolymer resins having different particle diameters, and the like.

  The structure of the rubber particles dispersed in the rubber-modified copolymer resin is not preferably an onion structure as described in JP-A-6-16744, and is a rubber particle other than the onion structure, such as a salami structure or a capsule structure. It is preferable. The ratio of the rubber particles other than the onion structure is preferably 50% or more, more preferably 60% or more, and particularly preferably 80% or more. The ratio of the rubber particles other than the onion structure is determined by observing the structure of about 3000 rubber particles in the photograph from the ultrathin section transmission electron micrograph of the resin. Area%. When the proportion of the rubber particles other than the onion structure is less than 50%, the practical impact resistance during low temperature molding may be lowered. The ratio of rubber particles other than the onion structure can be adjusted by the type and amount of the rubber-like polymer, the initiator, and the like.

The weight average molecular weight (Mw) of the matrix of the rubber-modified copolymer resin is 90,000 to 180,000, more preferably 100,000 to 170,000, and particularly preferably 130 to 170,000. When the weight average molecular weight (Mw) is less than 90,000, the practical impact resistance is lowered, and when it exceeds 180,000, the hue and transparency during low temperature molding are lowered. The weight average molecular weight (Mw) can be adjusted by an initiator, a chain transfer agent, a polymerization temperature condition, etc. used at the time of polymerization.
The weight average molecular weight (Mw) of the present invention is a polystyrene equivalent weight average molecular weight (Mw) measured by GPC, and was measured under the measurement conditions described below.

Device name: SYSTEM-21 Shodex (manufactured by Showa Denko)
Column: 3 series PL gel MIXED-B Temperature: 40 ° C
Detection: Differential refractive index Solvent: Tetrahydrofuran Concentration: 2% by mass
Calibration curve: produced using standard polystyrene (PS) (manufactured by PL), and the weight average molecular weight was expressed in terms of PS.

  The toluene-insoluble content of the rubber-modified copolymer resin exceeds 15% by mass and is 30% by mass or less, preferably 15.5 to 28% by mass, and more preferably 16 to 25% by mass. When the toluene insoluble content is 15% by mass or less, the impact resistance is inferior, and when the toluene insoluble content exceeds 30% by mass, the transparency and the hue are inferior. The toluene insoluble matter can be adjusted by the amount of the rubbery polymer.

The toluene insoluble matter in the present invention is measured as follows.
1 g of a sample was precisely weighed (a) and dissolved in 100 ml of toluene at a temperature of 25 ° C. for 24 hours, and then the lysate was transferred to a centrifuge tube having a capacity of 250 ml in which the mass (b) was measured in advance. Using an 8 cm angle rotor, centrifuge at a temperature of 10 ° C. or less and 8500 rpm for 60 minutes, remove non-precipitates by decantation, and dry in a vacuum dryer at a temperature of 70 ° C. for 24 hours. (D) is measured, and the toluene insoluble content is calculated by the following equation (2).

ゴム変性共重合樹脂の膨潤指数は膨潤指数が１０以上、好ましくは１０．５〜１７、さらに好ましくは１１〜１６である。膨潤指数が１０未満であると耐衝撃性が劣る。膨潤指数は、酸化防止剤の添加や、脱揮槽内の加熱条件等で調整できる。

The swelling index of the rubber-modified copolymer resin is 10 or more, preferably 10.5 to 17, and more preferably 11 to 16. If the swelling index is less than 10, the impact resistance is poor. The swelling index can be adjusted by adding an antioxidant, heating conditions in the devolatilization tank, or the like.

The swelling index is measured as follows.
1 g of a sample was precisely weighed (a) and dissolved in 100 ml of toluene at a temperature of 25 ° C. for 24 hours, and then the lysate was transferred to a centrifuge tube having a capacity of 250 ml in which the mass (b) was measured in advance. Centrifugation is performed at a temperature of 10 ° C. or less and 8500 rpm for 60 minutes using an 8 cm angle rotor, and after removing non-precipitates by decantation, the mass (c) of the centrifuge tube before drying is measured. It is dried in a vacuum dryer at a temperature of 70 ° C. for 24 hours, the mass (d) of the centrifuge tube after drying is measured, and the swelling index is calculated by the following equation (3).

本発明におけるゴム変性共重合樹脂の中に残存するスチレン系単量体と（メタ）アクリル酸エステル系単量体の合計は７００ｐｐｍ以下、好ましくは５００ｐｐｍ以下、さらに好ましくは３００ｐｐｍ以下である。樹脂中に残存する単量体の合計が７００ｐｐｍを越えると成形時の臭気や色相悪化の原因となる。樹脂中に残存する単量体は、脱揮槽内の圧力や温度条件、酸化防止剤等で調整できる。

The total of the styrene monomer and the (meth) acrylic acid ester monomer remaining in the rubber-modified copolymer resin in the present invention is 700 ppm or less, preferably 500 ppm or less, more preferably 300 ppm or less. If the total amount of monomers remaining in the resin exceeds 700 ppm, it may cause odor during molding or deterioration of hue. The monomer remaining in the resin can be adjusted by the pressure and temperature conditions in the devolatilization tank, the antioxidant, and the like.

The total of the styrene monomer and (meth) acrylate monomer remaining in the rubber-modified copolymer resin is measured by the GC method. In this invention, it implemented on the following conditions.
Device name: GC12A FID detector column manufactured by Shimadzu Corporation: Glass column φ3mm × 3m
Filler: Polyethylene glycol carrier: Nitrogen temperature: Column 115 ° C, inlet 220 ° C
Injection sample: 0.5 g of sample was dissolved in 10 ml of N, N-dimethylformamide containing cyclopentane as an internal standard.
Injection volume: 1 μl

The rubber-modified copolymer resin has a total light transmittance of 2% measured in accordance with JIS K7105 of 85% or more, preferably 88% or more, and more preferably 90% or more. When the total light transmittance is less than 85%, the transparency is low and the use is limited.
The total light transmittance can be adjusted by the refractive index of the rubber-like polymer, the composition of the styrene monomer to be copolymerized and the (meth) acrylate monomer, or the like.

The total light transmittance was measured as follows.
A 2 mm thick plate was molded at a mold temperature of 40 ° C. and a cylinder temperature of 230 ° C. using an injection molding machine (IS-50EPN) manufactured by Toshiba Machine. Using this molded product, the total light transmittance was measured using a HAZE meter (NDH-1001DP type) manufactured by Nippon Denshoku Industries Co., Ltd. (unit:%).

  In the rubber-modified copolymer resin, the b value (b *) of 2 mm thickness of a molded product at a mold temperature of 40 ° C. and a molding temperature of 230 ° C. is measured. This b value represents the hue, blueness and yellowness of the molded product, and the b value based on the Hunter diagram is adopted in accordance with JIS K7105. The range of the b value (* b) is not particularly defined, but is preferably less than 1.6. More preferably, it is less than 1.5, Most preferably, it is 1.4 or less. When the b value (b *) is 1.6 or more, the molded product tends to have a strong yellow tint and a poor hue.

  Rubber-modified copolymer resins may be added with weathering agents, lubricants, plasticizers, colorants, antistatic agents, mineral oil, flame retardants, MS resins, MBS resins, emulsion graft copolymers, etc. And can be added at any stage during manufacture. The method of adding is not particularly limited, and examples thereof include a method of adding at the time of polymerization and a method of melt kneading with an extruder.

  The rubber-modified copolymer resin is processed into various molded products by a known method such as injection molding, extrusion molding, compression molding, vacuum molding, etc., and is put to practical use.

  EXAMPLES Next, although an Example demonstrates this invention further, this invention is not limited by these examples.

  A first fully mixed reactor having a volume of about 5 liters equipped with a stirrer, a second fully mixed reactor having a volume of about 15 liters equipped with a stirrer, a column type plug flow reactor having a volume of about 40 liters, preheating A devolatilizing tank equipped with a vessel was connected in series. Asaprene 670A manufactured by Asahi Kasei Co., Ltd. as a rubbery polymer (styrene-butadiene rubber, styrene content 40% by mass, 5% by mass styrene solution viscosity at 25 ° C. 33 mPa · s, 1,2-vinyl bond ratio 13.9 mol% ) 7 parts by mass is dissolved in a mixed solution composed of 44 parts by mass of styrene, 31 parts by mass of methyl methacrylate (hereinafter referred to as MMA), 6 parts by mass of n-butyl acrylate (hereinafter referred to as n-BA), and 12 parts by mass of ethylbenzene. Furthermore, 0.02 parts by mass of 1,1-bis (t-butylperoxy) -cyclohexane (manufactured by NOF Corporation, Perhexa C, 1 hour half-life temperature 111.1 ° C.), octadecyl-3- (3,5-di- 0.2 quality of t-butyl-4-hydroxyphenyl) propionate (IRGANOX1076 manufactured by Ciba Specialty Chemicals) Parts were mixed with the raw material solution. This raw material solution was introduced into a first complete mixing reactor controlled at a temperature of 110 ° C. at 7 kg / hour. The reaction solution was continuously withdrawn from the first complete mixing reactor, and 3.0 g of n-dodecyl mercaptan (Kio Co., thiocalcol 20) was added to the reaction solution every hour, and then the temperature was controlled at 130 ° C. It was introduced into the type reactor. The number of stirrings in the second complete mixing type reactor was 100 rpm. Next, the reaction solution was continuously withdrawn from the second complete mixing reactor, and 3.0 g / h of n-dodecyl mercaptan and di-t-butyl peroxide (Perbutyl D, manufactured by NOF Corporation, 1 hour half-life). Was added to a tower-type plug flow reactor adjusted so that a gradient from 130 ° C. to 150 ° C. was formed in the direction of flow. While this reaction solution was heated with a preheater, it was introduced into a devolatilization tank controlled at a temperature of 240 ° C. and a pressure of 1.0 kPa to remove volatile components such as unreacted monomers. The resin liquid was extracted with a gear pump and extruded and cut into a strand shape to obtain a pellet-shaped resin. Table 1 shows the physical property evaluation results.

It carried out similarly to Example 1 except having controlled the pressure of the devolatilization tank to 2.0 kPa. Table 1 shows the physical property evaluation results.

9 parts by mass of a rubber-like polymer is dissolved in a mixed solution composed of 43 parts by mass of styrene, 30 parts by mass of MMA, 6 parts by mass of n-BA, and 12 parts by mass of ethylbenzene, and the number of stirring of the second complete mixing type reactor is 150 rpm. The same procedure as in Example 1 was performed except that. Table 1 shows the physical property evaluation results.

It carried out similarly to Example 1 except having controlled the resin temperature in a devolatilization tank to 255 degreeC. Table 1 shows the physical property evaluation results.

The same procedure as in Example 1 was conducted except that 7 parts by mass of a rubber-like polymer was dissolved in a mixed solution composed of 46 parts by mass of styrene, 29 parts by mass of MMA, 6 parts by mass of n-BA, and 12 parts by mass of ethylbenzene. Table 1 shows the physical property evaluation results.

  The same procedure as in Example 1 was conducted except that octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate was not added to the raw material solution. Table 1 shows the physical property evaluation results.

The same procedure as in Example 1 was carried out except that di-t-butyl peroxide was not added to the reaction solution. Table 1 shows the physical property evaluation results.

  Bayer Buna BL6533 (styrene-butadiene rubber, styrene content 40% by mass, styrene solution viscosity 36 mPa · s at a temperature of 25 ° C., 1,2-vinyl bond ratio 8.5 mol% as a rubbery polymer. ) Was carried out in the same manner as in Example 1. Table 1 shows the physical property evaluation results.

It carried out similarly to Example 1 except having controlled the resin temperature in a devolatilization tank to 228 degreeC. Table 1 shows the physical property evaluation results.

11 parts by mass of a rubber-like polymer was dissolved in a mixed solution composed of 42 parts by mass of styrene, 29 parts by mass of MMA, 6 parts by mass of n-BA, and 12 parts by mass of ethylbenzene, and the number of stirring in the second complete mixing type reactor was 200 rpm. The same procedure as in Example 1 was performed except that. Table 1 shows the physical property evaluation results.
Comparative Example 1

It carried out similarly to Example 1 except having controlled the pressure of the devolatilization tank to 7.0 kPa. Table 2 shows the physical property evaluation results.
Comparative Example 2

It carried out like Example 1 except having controlled the resin temperature in a devolatilization tank to 220 degreeC. Table 2 shows the physical property evaluation results.
Comparative Example 3

5 parts by mass of a rubber-like polymer is dissolved in a mixed solution composed of 45 parts by mass of styrene, 32 parts by mass of MMA, 6 parts by mass of n-BA, and 12 parts by mass of ethylbenzene, and the stirring number of the second complete mixing type reactor is 70 rpm. The same procedure as in Example 1 was performed except that. Table 2 shows the physical property evaluation results.
Comparative Example 4

The same procedure as in Example 1 was conducted except that 7 parts by mass of a rubber-like polymer was dissolved in a mixed solution composed of 50 parts by mass of styrene, 25 parts by mass of MMA, 6 parts by mass of n-BA, and 12 parts by mass of ethylbenzene. Table 2 shows the physical property evaluation results.
Comparative Example 5

The same procedure as in Example 4 was conducted except that octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate was not added to the raw material solution. Table 2 shows the physical property evaluation results.
Comparative Example 6

It carried out similarly to Example 1 except having controlled the resin temperature in a devolatilization tank to 265 degreeC. Table 2 shows the physical property evaluation results.
Comparative Example 7

The same procedure as in Example 1 was conducted except that 1,1-bis (t-butylperoxy) -cyclohexane was not added to the raw material solution and di-t-butyl peroxide was not added to the reaction solution. Table 2 shows the physical property evaluation results.

  Examples relating to rubber-modified copolymer resins all have a good balance between transparency and impact resistance, good recyclability, and a balance between transparency and impact resistance in comparative examples that do not meet the conditions of the present invention. Was good, and any of the physical properties of the recyclability was inferior.

Evaluation was based on the following method.
(1) Toluene insolubles were measured by the method described above.
(2) The swelling index was measured by the method described above.
(3) The total of the styrene monomer and (meth) acrylic acid ester monomer remaining in the resin was measured by the method described above.
(4) Volume average particle diameter (dv) of rubber particles and ratio of salami structure particles Ultrathin section transmission electron micrographs of rubber-modified copolymer resin dyed with osmic acid were taken. About 3,000 particles in the photograph (= (major axis + minor axis) / 2) were measured using an image processing measuring device KS400 manufactured by Carl Zeiss Vision, volume average particle size (dv) and salami structure particles. The ratio was calculated.
(5) The weight average molecular weight (Mw) was measured by the method described above.

(6) Transparency Using a Toshiba Machine Co., Ltd. injection molding machine (IS-50EPN), a plate having a thickness of 2 mm was molded at a mold temperature of 40 ° C and a cylinder temperature of 230 ° C. Using this molded product, the total light transmittance and haze value were measured according to JIS K7105 as a measure of transparency (unit:%). In addition, the Nippon Denshoku Industries Co., Ltd. HAZE meter (NDH-1001DP type) was used for the measuring machine. A total light transmittance of 85% or more and a haze value of 4% or less were accepted.
(7) Impact resistance As a measure of impact resistance, a Charpy impact strength was measured using a type 1 test piece having a notch type A based on JIS K7111, and using an edgewise impact direction (unit: kJ). / M ² ). The measuring instrument used was a digital impact tester manufactured by Toyo Seiki Seisakusho. Charpy impact strength of 8 kJ / m ² or more was regarded as acceptable.
(8) Hue Using a Toshiba Machine Co., Ltd. injection molding machine (IS-50EPN), a plate having a thickness of 2 mm was molded at a mold temperature of 40 ° C and a cylinder temperature of 230 ° C. Using this molded product, b * was measured using a color difference meter (Σ80) manufactured by Nippon Denshoku Industries Co., Ltd. (unit: −) according to JIS K7105 as a measure of color difference.

(9) Recyclability As a judgment on recyclability, changes in physical properties during repeated extrusion were investigated. That is, using a 40 mm single screw extruder manufactured by IKG with a dalmage type screw, extrusion was performed at a cylinder temperature of 230 ° C. and a screw rotation speed of 100 rpm, and then pelletized by a pelletizer was repeated five times. The sample subjected to repeated extrusion was subjected to the measurement of impact resistance and hue as described above. Regarding the hue, the difference (Δb * = b * 2−b * 1) between b * (b * 2) after repeated extrusion and b * (b * 1) before execution is 0.4 or less. Things were accepted.
(10) Odor during recycling The odor during repetitive extrusion is sniffed directly by five measurers, 1 point (no odor), 2 points (slightly smelling), 3 points (smelling), 4 points (smelling), 5 Evaluation was made on a 5-point scale (unbearable). A case where the total score of 5 people was less than 10 was judged as ◎, a case where it was 10 or more and less than 15 points, and a case where 15 or more points were ×.

The rubber-modified copolymer resin of the present invention has a good hue, a small amount of residual monomer after polymerization, a good balance between transparency and impact resistance, and good recyclability. It can be applied to various uses including materials and sheets.

Claims (4)

Obtained by copolymerizing a styrene monomer and a (meth) acrylic acid ester monomer in the presence of a rubbery polymer, the total light transmittance at a thickness of 2 mm measured based on JIS K7105 is 85. % Of a rubber-modified copolymer resin having a volume average particle size (dv) of 0.4 to 1.6 μm and a weight average molecular weight (Mw) of a matrix of 90,000 to 18 The toluene insoluble content exceeds 15 mass% and is 30 mass% or less, the swelling index is 10 or more, and the total of the styrene monomer and (meth) acrylate monomer remaining in the resin is 700 ppm or less. A rubber-modified copolymer resin characterized by The rubber-modified copolymer resin according to claim 1, wherein the ratio of rubber particles other than the onion structure is 50% or more. A sheet using the rubber-modified copolymer resin according to claim 1 or 2. The method for producing a rubber-modified copolymer resin according to claim 1 or 2, wherein devolatilization is performed at a resin temperature of 230 to 260 ° C and a pressure of 6 kPa or less in the presence of a hindered phenol-based antioxidant.