JP2006022257A - Sheet formed out of rubber-modified copolymer resin, and molded product for packaging - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet having excellent transparency, strength and rigidity by forming a transparent rubber-modified copolymer resin containing rubber particles having specific diameters; and to provide a molded product for packaging. <P>SOLUTION: The sheet is formed out of a rubber-modified copolymer resin obtained by copolymerizing a styrenic monomer, a (meth)acrylic ester-based monomer and optionally other monomers copolymerizable with these monomers in the presence of a gummy polymer, wherein the volume averaged particle diameter (dv) of the rubber particles dispersed in the resin is 0.4-1.2 μm, the percentage of particles having ≤1.5 μm volume average particle diameter is <15% of the whole particles, and the content of the gummy polymer is 1-10 mass% based on the rubber-modified copolymer resin. The molded product of the sheet is also provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a sheet molded from a rubber-modified copolymer resin having good transparency and excellent practical strength, and a molded article for packaging.

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 view of the balance of the above, and the excellent processability of styrenic resins, it has been widely used in the fields of injection molding and extrusion (for example, Patent Document 1). Especially in the field of extrusion applications, it is widely used as a food packaging material and electronic packaging material due to its excellent transparency and processability, and a molded body can be obtained by thermoforming the resin in sheet form, and it has excellent transparency and strength. It is used as a container. These packaging moldings are characterized by excellent transparency / strength / rigidity balance. However, since these molded products are often obtained by thermoforming after sheet processing from the viewpoint of productivity, even if the surface is mirror-finished at the sheet processing stage, the rubber-like material present in the resin by subsequent thermoforming There was a problem that the surface was clouded by the influence of the polymer and the image clarity was lowered.

Japanese Patent Laid-Open No. 11-60653

It is an object of the present invention to provide a sheet that has little deterioration in surface image clarity even when thermoformed and has excellent transparency, rigidity, and practical strength, and a molded article for packaging obtained by molding the sheet. And

As a result of diligent investigations on the method for obtaining a well-balanced, transparent sheet and molded body excellent in practical strength and transparency (image clarity) as a sheet and a molded body, the present inventors have determined that the problem has been solved. It has been found that by using a transparent rubber-modified copolymer resin having a rubber particle diameter of the above, a sheet excellent in transparency, strength and rigidity and a molded article for packaging can be obtained, and the present invention has been completed.

That is, the present invention relates to 1) a styrene monomer, a (meth) acrylic acid ester monomer, and other monomers copolymerizable with these monomers as required in the presence of a rubber-like polymer. A rubber-modified copolymer resin obtained by copolymerizing a body, and a volume average particle diameter (dv) of rubber particles dispersed in the rubber-modified copolymer resin is 0.4 to 1.2 μm, volume particles The present invention relates to a sheet characterized in that the number of particles having a diameter of 1.5 μm or more is less than 15% of the total, and the rubber-like polymer is contained in 1 to 10% by mass in the rubber-modified copolymer resin.

2) The rubbery polymer is selected from polybutadiene, styrene-butadiene rubber, styrene-butadiene block rubber, partially hydrogenated polybutadiene, partially hydrogenated styrene-butadiene rubber, and partially hydrogenated styrene-butadiene block rubber. Sheet, 3) The rubber-like polymer is a styrene-butadiene rubber or styrene-butadiene block rubber having a styrene content of 32 to 45 parts by mass. 1) The sheet of 1 or 2), 4) In the rubber-like polymer, 2, The sheet according to any one of 1) to 3), wherein 4-bis [(octylthio) methyl] -O-cresol is added in an amount of 0.02 to 0.3% by mass with respect to 100% by mass of the rubber-like polymer. 5) 1 to 99 parts by mass of a styrene monomer, 99 to 1 part by mass of a (meth) acrylic acid ester monomer, and other monomers that can be copolymerized with these monomers as required 0 10 parts by mass (provided that the total amount of monomers is 100 parts by mass) in the presence of a rubber-like polymer, and any one of 1) to 4), 6) molecular weight regulator 0.005 to 5 parts by weight based on a total of 100 parts by mass of styrene monomer, (meth) acrylic acid ester monomer and other monomers copolymerizable with these monomers if necessary 1) to 5 parts of the sheet to be added by mass, 7) a molded body formed by thermoforming any of the sheets 1) to 6), and 8) a molded body formed by vacuum forming the sheet of 7). 9) A molded article for packaging according to 7) or 8) characterized by being used for food packaging, 10) Electric Packaging molded article 7) or 8) used in the packaging material about.

The sheet of the present invention molded from a transparent rubber-modified copolymer resin is excellent in transparency, rigidity, and strength, and a molded product formed by thermoforming the sheet is excellent in balance of transparency, strength, and image clarity. It is useful for the use of the molded article for packaging.

The present invention is described in detail below.
The rubber-modified copolymer resin is a copolymer of a styrene monomer and a (meth) acrylate monomer, but if necessary, a styrene monomer and a (meth) acrylate monomer Other monomers copolymerizable with the body may be used.

Examples of the styrenic monomer include styrene, α-methyl styrene, p-methyl styrene, pt-butyl styrene, and the like, and styrene is preferable. These styrene monomers may be used alone or in combination of two or more.

Examples of (meth) acrylic acid ester monomers include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-methylhexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, methyl acrylate, ethyl acrylate, n-butyl acrylate, Examples include 2-methylhexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, and the like, preferably methyl methacrylate or n-butyl acrylate. These (meth) acrylic acid ester monomers may be used alone or in combination of two or more.

Examples of other monomers copolymerizable with the styrene monomer and the (meth) acrylic acid ester monomer include acrylonitrile, n-butyl acrylate, methacrylic acid, maleic anhydride and the like.

The proportion of the monomer is preferably styrene monomer: (meth) acrylic acid ester monomer: other monomer = 1 to 99 parts by mass: 99 to 1 part by mass: 0 to 10 parts by mass. More preferably, it is 5 to 95 parts by mass: 95 to 5 parts by mass: 0 to 5 parts by mass. However, the total of the styrene monomer, the (meth) acrylic acid ester monomer and other monomers is 100 parts by mass.

Examples of the rubber-like polymer include polybutadiene, styrene-butadiene rubber, styrene-butadiene block rubber, partially hydrogenated polybutadiene, partially hydrogenated styrene-butadiene rubber, and partially hydrogenated styrene-butadiene block rubber. Two or more kinds can be used. Preferably, styrene-butadiene rubber or styrene-butadiene block rubber having a styrene content of 32 to 45 parts by mass can be used.

The ratio of the rubber-like polymer is preferably 1 to 10 parts by mass with respect to a total of 100 parts by mass of the styrene monomer, the (meth) acrylic acid ester monomer, the other monomers, and the rubber-like polymer. More preferably, it is 2-7 mass parts, Most preferably, it is 3.5-7 mass parts. When the rubber-like polymer is less than the above range, the molded body has high rigidity but tends to be inferior in impact resistance. When the rubbery polymer exceeds the range, the rigidity of the molded body tends to decrease, which is not preferable as a molded body for packaging. There is.

In the present invention, various additives can be contained in the rubber-like polymer as necessary. As an example, for the purpose of improving thermal stability, it is desirable that 2,4-bis [(octylthio) methyl] -O-cresol is contained in the rubber-like polymer. The content thereof is 0.02 to 0.3% by mass, preferably 0.06 to 0.15% by mass, and more preferably 0.08 to 0.12% by mass with respect to 100% by mass of the rubber-like polymer. is there. If the amount is outside this range, the reaction may be inhibited during the polymerization, or the swelling index by toluene may be affected to lower the practical strength.

The rubber-like polymer can be used for polymerization after being dissolved in, for example, a styrene monomer, a (meth) acrylic acid ester monomer, and other monomers.

As the copolymerization method, for example, known methods such as solution polymerization, bulk polymerization, suspension polymerization and the like can be adopted, and any of a batch polymerization method and a continuous polymerization method may be used, but the polymerization is performed in a solution or a bulk shape. After that, the continuous polymerization method of bulk polymerization or solution polymerization which is exposed to a high temperature in a devolatilization preheater / devolatilization tank is preferable because a particularly high effect is obtained.

Examples of the polymerization initiator include known azo compounds such as azobisisobutyronitrile and azobiscyclohexanecarbonitrile, benzoyl peroxide, t-butylperoxybenzoate, 1,1-bis (t-butylperoxy)- 3,3,5-trimethylcyclohexane, t-butylperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexanoate, di-t-butyl peroxide, dicumyl peroxide, ethyl-3,3- Known organic peroxides such as di- (t-butylperoxy) butyrate can be used, but organic peroxides having a one-hour half-life temperature of 90 to 130 ° C. are preferred. The added amount of the organic peroxide is 0.05 to 0.5 parts by mass, more preferably 100 parts by mass in total of the styrene monomer, the (meth) acrylic acid ester monomer and other monomers. Is preferably 0.08 to 0.1 parts by mass. When the amount is 0.05 parts by mass or less, the effect of the present invention is low, and when the amount is 0.5 parts by mass or more, the polymerization rate may become too fast and control may be difficult. These organic peroxides may be used alone or in combination of two or more.

At the time of polymerization, it is preferable to add at least one known molecular weight regulator such as 4-methyl-2,4-diphenylpentene-1, t-dodecyl mercaptan, n-dodecyl mercaptan.
The addition amount of the molecular weight modifier is preferably 0.005 to 5 parts by mass, more preferably 0 with respect to 100 parts by mass in total of the styrene monomer, the (meth) acrylate monomer and other monomers. 0.01 to 1 part by mass. If it is outside this range, the purpose may not be achieved.

As an antioxidant, for example, octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) Propionate, 2,4-dimethyl-6- (1-methylpentadecyl) phenol, 3,3 ′, 3 ″, 5,5 ′, 5 ″ -hexa-tert-butyl-a, a ′, a ′ '-(Mesitylene-2,4,6-triyl) tri-p-cresol, 4,6-bis (octylthiomethyl) -o-cresol, ethylenebis (oxyethylene) bis [3- (5-tert-butyl -4-hydroxy-m-tolyl) propionate, 1,3,5-tris (3,5-dirt-butyl-4-hydroxybenzyl) -1,3,5-tria 2,4,6 (1H, 3H, 5H) -trione, 2,6-dirt-butyl-4- (4,6-bis (octylthio) -1,3,5-triazin-2-ylamino) phenol, etc. Although known antioxidants can be used, octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate is preferred.

The addition amount of the antioxidant is preferably 0.05 to 5 parts by mass, more preferably 0 with respect to 100 parts by mass in total of the styrene monomer, the (meth) acrylate monomer and other monomers. .1 to 1 part by mass. 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 Is not preferable because the yellowishness of the resin tends to increase.

After the polymerization, it is desirable to carry out devolatilization using known equipment such as two or more devolatilization tanks and / or an extruder for the purpose of removing unreacted monomers and solvents. At this time, in the first devolatilization tank, the resin temperature is preferably 150 to 200 ° C. and the pressure is 100 kPa or less, more preferably, the resin temperature is 160 to 190 ° C. and the pressure is 90 kPa or less. desirable. In the second and subsequent devolatilization tanks, devolatilization is preferably performed at a resin temperature of 220 to 260 ° C. and a pressure of 7 kPa or less, 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 residual volatile content in the resin is large, and the balance between transparency and impact resistance may be poor.

Rubber particles are dispersed in the rubber-modified copolymer resin. The volume average particle diameter (dv) of the rubber particles is 0.4 to 1.2 μm, preferably 0.4 to 1.1 μm, more preferably 0.5 to 1.0 μm, and the volume particle diameter is 1. The number of particles of 5 μm or more is less than 15% of the whole. If it is outside this range, the balance between transparency and impact resistance may be inferior in a molded product that places importance on transparency. In particular, large particles of 1.5 μm or more may deteriorate the appearance of the surface (decrease image clarity) in a molded product obtained by sheet molding, and the number of particles having a volume particle diameter of 1.5 μm or more is 15% of the total. It is desirable that it is less than 0.1%, preferably 0.1 to 14%, particularly preferably 3 to 13%. If it is 15% or more, the strength of the molded product can be obtained, but the image clarity of the molded product may be remarkably inferior.

The volume average particle size (dv) of the present invention is such that Beckman Coulter Co., Ltd. was prepared by dissolving a resin or polymerization solution in dimethylformamide and dispersing it in an ultrasonic dissolution tank for about 30 minutes and filling it with dimethylformamide. The particle diameter (volume sphere equivalent diameter = (6v / π) 1/3) measured by polarization scattering intensity difference measurement (PIDS theory) was dropped into a laser diffraction / scattering particle size distribution measuring device (LS-230). It calculated | required and calculated | required as an average particle diameter obtained by following Formula number 1. The number of particles of 1.5 μm or more was calculated by converting the particle size distribution obtained by measurement into cumulative frequency.

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される。体積平均粒子径（ｄｖ）の制御は例えば、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 proceeds when the rubber-modified copolymer resin is polymerized. The volume average particle diameter (dv) can be controlled by, for example, the number of stirring during polymerization, the addition amount of a polymerization initiator or a molecular weight modifier, and the mixing of rubber-modified copolymer resins having different particle diameters.

The weight average molecular weight of the rubber-modified copolymer resin is preferably 40000 to 500000, more preferably 60000 to 200000. When the weight average molecular weight (Mw) is outside this range, the balance between moldability, transparency and impact strength may be poor. 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 rubber-modified copolymer resin is a polystyrene equivalent weight average molecular weight (Mw) measured by GPC, and was measured under the measurement conditions described below.
Device name: GPC-8020 (manufactured by Tosoh Corporation)
Column: 4 KF404-HQ (manufactured by Shodex) Temperature: 40 ° C
Detection: Differential refractive index Solvent: Tetrahydrofuran Concentration: 0.3% by mass
Calibration curve: produced using standard polystyrene (PS) (manufactured by PL), and the weight average molecular weight was expressed in terms of PS.

“Molded body obtained by thermoforming” means sheets made by various methods such as T-die method, casting method, calendar method, etc., such as hot plate forming, vacuum forming, vacuum / pressure forming, plug assist vacuum forming, etc. It refers to a molded body obtained by various thermoforming methods for reheating and molding. Such a method for producing a molded body is not limited to a transparent resin and an opaque resin, and is a method widely used as a method for producing a thin packaging container.

The transparency of the molded body refers to how the contents are visible (crispness) when the molded body is used as a container, and can be judged as image clarity. The evaluation of the image clarity is obtained as the image clarity value (C%) by the following formula using the transmitted light obtained by cutting out the molded body obtained by sheet molding and transmitting the light, and visually clear feeling And correspondence is obtained.
C = (M−m) / (M + m) × 100
M: Maximum value of transmitted light in optical comb light portion m: Minimum value of transmitted light in dark portion of optical comb

Additives such as weathering agents, lubricants, plasticizers, colorants, antistatic agents, mineral oils, flame retardants and the like can be added to the copolymer resin of the present invention as needed, and are blended at any stage during production. can do.

EXAMPLES Next, although an Example demonstrates this invention further, this invention is not limited by these examples.
(Rubber polymer A)
For the rubbery polymer A, the conditions of the method for producing a styrene-butadiene random copolymer rubber by living anionic polymerization such as US 3,094,512 are mostly used. Specifically, a stainless steel polymerization tank with a jacket, coil, and stirrer with an internal volume of 1000 L was washed with cyclohexane dehydrated to a moisture content of 10 ppm or less, purged with nitrogen, and dehydrated to a moisture content of 10 ppm or less in a nitrogen gas atmosphere. Then, 540 kg of cyclohexane containing 152 ppm of tetrahydrofuran was charged into the polymerization tank, and after raising the internal temperature to 80 ° C., 0.8 kg of a cyclohexane solution of 10 wt% n-butyllithium was added. Next, styrene dehydrated to a water content of 10 ppm or less under a constant internal temperature of 80 ° C. at a rate of 6.25 kg / hr, and butadiene dehydrated by passing through a molecular sieve at the same time for 4 hours at a rate of 35 kg / hr. Added and polymerized. Thereafter, 65 kg of styrene dehydrated to a water content of 10 ppm or less was added at 80 ° C., and polymerization was performed for 10 minutes within a range where the maximum temperature did not exceed 120 ° C., and all of the charged styrene was polymerized. Thereafter, the polymerization solution was transferred to the next reaction vessel, 0.08 parts by mass of water was added to 100 parts by mass of the polymer to stop the polymerization, and carbon dioxide gas was added during the transition to the next reaction vessel. It was summed up.
Next, 2,4-bis [(octylthio) methyl] -O-cresol (IRGNOX1520L manufactured by Ciba Specialty Chemicals Co., Ltd.) and octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) For a total of 100 parts by weight of monomers charged with propionate (IRGNOX 1076 manufactured by Ciba Specialty Chemicals Co., Ltd.), 0.08 parts by weight and 0.24 parts by weight were added respectively, and then the solvent was removed by steam stripping. A styrene-butadiene rubber-like polymer A was obtained by drying with a hot roll at 100 ° C.

(Rubber-modified copolymer resin T-1)
Two devolatilization tanks with a first reactor, a fully mixed stirring tank with a capacity of about 5 L, a second reactor with a capacity of about 20 L, a tower-type plug flow reactor with a capacity of about 40 L, and a preheater are connected in series. Connected and configured. 7 parts by mass of the rubber-like polymer A obtained in Reference Example 1 was 44 parts by mass of styrene, 31 parts by mass of methyl methacrylate (hereinafter MMA), 6 parts by mass of n-butyl acrylate (hereinafter n-BA), and 12 parts by mass of ethylbenzene. Dissolved in the mixed solution constituted, and further 0.01 part by mass of 1,1-bis (t-butylperoxy) -cyclohexane (Perhexa C, 1-hour half-life temperature 111.1 ° C. manufactured by NOF Corporation), octadecyl- 0.2 parts by mass of 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate (IRGANOX1076 manufactured by Ciba Specialty Chemicals) was mixed to obtain a raw material solution. This raw material solution was introduced into the first reactor controlled at a temperature of 110 ° C. at a rate of 7 kg / hr. The reaction solution was continuously withdrawn from the first reactor, and n-dodecyl mercaptan (Tiocalcol 20 manufactured by Kao Corporation) was added to the reaction solution at a rate of 3.0 g / hr, and then the temperature was controlled at 130 ° C. Introduced into the vessel. The second reactor was stirred at 100 rpm. Next, the reaction solution was continuously withdrawn from the second reactor, and n-dodecyl mercaptan was added to the reaction solution at a rate of 3.0 g / hr, and then a gradient from 130 ° C. to 150 ° C. in the flow direction was observed. It was introduced into a tower-type plug flow reactor adjusted so as to be attached. While heating this reaction liquid with a preheater, it was introduced into the first devolatilization tank controlled at a temperature of 175 ° C. and a pressure of 70 kPa, and further introduced into a devolatilization tank controlled at a temperature of 240 ° C. and a pressure of 0.7 kPa. Then, volatile components such as unreacted monomers were removed. This resin liquid was extracted with a gear pump, extruded into a strand shape, cut with water, and then cut to obtain a pellet-shaped resin T-1. Table 1 shows the physical property evaluation results.

(Rubber-modified copolymer resin T-2 to T-5)
Except having changed the stirring number of the 2nd reactor, it carried out like T-1 and obtained rubber-modified copolymer resin T-2 to T-5 from which a rubber particle diameter differs. That is, when a rubber particle size larger than T-1 is obtained, rotation is performed at a lower speed than the number of stirring during the production of T-1 (T-3, T-5). The rotation was performed at a higher speed than the number of stirring (T-4). Table 1 shows the physical property evaluation results.

(Rubber-modified copolymer resin T-6)
Except that the blending amount was changed to 11 parts by mass of rubber-like polymer A, 41.8 parts by mass of styrene, 29.5 parts by mass of MMA, 5.7 parts by mass of n-BA, and the same as T-1, the rubber particle diameter was T The rubber-modified copolymer resin T-6 was obtained by changing the stirring number of the second reactor so as to be equal to -1. Table 1 shows the physical property evaluation results.

Examples 1-5 Comparative Examples 1-6
Hand blended materials at the compounding ratio shown in Table 2 to create a 0.3mm thick sheet. Thereafter, vacuum forming (without plug) was performed using the sheet sample to obtain a formed body having the shape shown in FIG. The obtained molded product was evaluated for the characteristics shown in Table 1. As for the material to be blended, a 2 mmt molded product was separately prepared by injection molding and the transparency was confirmed. The following resins used for blending the transparent resin are the following MMA-St copolymer resins having the same refractive index (Nd: 1.55) as the rubber-modified copolymers (T-1 to T-6). (MS resin) was used together.
TX-800 (Denka TX polymer: manufactured by Denki Kagaku Kogyo Co., Ltd.): MS resin

In all of the examples relating to the sheet and the molded product molded from the rubber-modified copolymer resin of the present invention, a molded product for packaging excellent in the balance of transparency, strength and image clarity was confirmed. In the comparative example which does not match, it was inferior in any physical property (characteristic).

The evaluation was based on the following method.
(1) The volume average particle diameter (dv) of the rubber particles was measured by the method described above.
(2) The weight average molecular weight (Mw) was measured by the method described above.
(3) 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 60 ° 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.
(4) MFR
Evaluation was performed based on JIS K6874 (200 ° C./5 kg load).
(5) Tensile modulus A tensile test was performed according to JIS K7113 (test piece shape; JIS-2 dumbbell, distance between chucks: 50 mm, pulling speed: 5 mm / min).
(6) Sheet extrusion Using a Tanabe Plastic Machine Co., Ltd. extruder (V-40 / 800 type: full flight screw), a sheet having a roll temperature of 70 ° C. and a cylinder temperature of 230 ° C. and a thickness of 0.3 mm was prepared. .
(7) Sheet impact Evaluation was performed using a 0.3 mm thick sheet sample obtained by sheet extrusion.
A tip-shaped (R10) impact indenter was used. (Unit: N / mm).
(8) Formation of molded body The container shown in Fig. 1 was formed by vacuum forming (without plug).
Preheating temperature: 120 ° C
(9) Evaluation of image clarity The top surface of the molded product prepared in (8) above was cut out, and the image clarity at the center of the top surface was evaluated with a image clarity measuring instrument (manufactured by Suga Test Instruments). 2mm is used for the optical comb.
Further, the molded product was placed on a newspaper, and the appearance of the characters below were compared, and those having difficulty in seeing the characters were visually judged as image clarity x.
(10) Bending test The molded product prepared in the above (8) was bent by 180 degrees by hand from the center, and the occurrence of cracks was observed (n = 3).

It is the shape of the molded article for evaluation.

Claims (10)

Obtained by copolymerizing styrene monomers, (meth) acrylate monomers, and other monomers copolymerizable with these monomers as necessary in the presence of rubbery polymers. The rubber-modified copolymer resin is a sheet formed by molding, and the rubber particles dispersed in the rubber-modified copolymer resin have a volume average particle diameter (dv) of 0.4 to 1.2 μm and a volume particle diameter of 1.5 μm or more. A sheet characterized in that the number of particles is less than 15% of the total, and the rubber-like polymer is contained in the rubber-modified copolymer resin in an amount of 1 to 10% by mass. The rubbery polymer is selected from polybutadiene, styrene-butadiene rubber, styrene-butadiene block rubber, partially hydrogenated polybutadiene, partially hydrogenated styrene-butadiene rubber, and partially hydrogenated styrene-butadiene block rubber. The sheet according to 1. The sheet according to claim 1 or 2, wherein the rubbery polymer is a styrene-butadiene rubber or a styrene-butadiene block rubber having a styrene content of 32 to 45 parts by mass. The rubbery polymer is characterized by adding 0.02 to 0.3% by mass of 2,4-bis [(octylthio) methyl] -O-cresol with respect to 100% by mass of the rubbery polymer. The sheet according to any one of claims 1 to 3. 1 to 99 parts by mass of a styrene monomer, 99 to 1 part by mass of a (meth) acrylic acid ester monomer, and other monomers 0 to 10 copolymerizable with these monomers used as necessary The sheet according to any one of claims 1 to 4, wherein the sheet is obtained by polymerizing part by mass (provided that the total amount of monomers is 100 parts by mass) in the presence of a rubbery polymer. . The molecular weight modifier is added to the total amount of 100 parts by mass of the styrene monomer, the (meth) acrylic acid ester monomer, and other monomers copolymerizable with these monomers as required. 005-5 mass parts is added, The sheet | seat of any one of Claims 1-5 characterized by the above-mentioned. The molded object formed by thermoforming the sheet | seat of any one of Claims 1-6. A molded body obtained by vacuum forming the sheet according to claim 7. The packaging molded body according to claim 7 or 8, which is used for food packaging. The molded article for packaging according to claim 7 or 8, which is used for an electronic packaging material.

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