JP2006306902A - Heat-resistant styrenic resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a styrenic resin excellent in heat resistance, melt stability and recyclability. <P>SOLUTION: The heat-resistant styrenic resin composition consists of (I) a styrenic copolymer, which is a copolymer containing an isopropenyl aromatic unit represented by formula (1) and a vinyl aromatic unit represented by formula (2), in which the content (A) of the isopropenyl aromatic unit is 5-70 (wt.%) and in which the ratio (Mz/Mw) of the Z average mol.wt. (Mz) to the weight average mol.wt. (Mw) of the copolymer is 1.4-3.0, and (II) an impact-resistant styrenic resin comprising a styrenic monomer unit and containing gel-like rubber particles. The weight ratio (I/II) of the component (I) to the component (II) satisfies: I/II=99/1-1/99. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to a styrenic resin composition excellent in heat resistance, melt stability, recyclability, moldability, strength, and rigidity.

Styrenic resin not only excels in material performance such as transparency, rigidity, and dimensional stability, but also enables various molding processes such as injection molding, stretched sheet, film, foamed sheet, foamed board, and blow molding. In addition, many styrene resins are used in a wide variety of applications because they can be manufactured in large quantities at low cost by bulk polymerization by radical polymerization, solution polymerization by high monomer concentration, suspension polymerization, and emulsion polymerization. Yes.
Typical examples of the styrene resin include polystyrene (GPPS), styrene / acrylonitrile (AS), styrene / methyl methacrylate (MS), styrene methacrylic acid (SMAA), styrene / maleic anhydride (SMA), and the like. However, among these, styrene homopolymer (polystyrene, GPPS) is the most widely used resin.

Polystyrene has many excellent performances and has a high utility value because it is inexpensive, and is used in various applications. The main applications are specifically described as follows.
(Packaging applications)
Lunch box (foamed sheet: PSP), cup noodle container (foamed sheet: PSP), transparent cup, spoon, fork, vegetable packaging sheet (biaxially stretched sheet), envelope window (for home appliance OA use)
TV, air conditioner, OA equipment housing, electric refrigerator tray, cassette / MD / MO shell (daily goods)
Toys, stationery supplies (building materials)
Thermal insulation material (foam board), tatami mat (foam board)

  However, there are uses that cannot be satisfied even with the performance of this resin, for example, uses that lack heat resistance and cannot be used. Specifically, since GPPS has a heat resistance of about 100 ° C. (glass transition temperature), it is easy to be exposed to high-temperature atmospheres in summer, for use in contact with water vapor for boiling disinfection, for food packaging that requires microwave heating. In the case of molded products for mounting on vehicles, it was impossible to use them with peace of mind because there was a risk of deformation of the molded products.

  One technique for increasing the heat resistance of polystyrene is to copolymerize a monomer containing a polar functional group with styrene. For example, there are copolymers of styrene and methacrylic acid (SMAA), copolymers of styrene and maleic anhydride (SMA), copolymers of styrene and maleimide, etc., and monomers having polar functional groups The heat resistance can be arbitrarily changed by controlling the amount of copolymerization.

  For example, a typical SMAA as a heat-resistant styrene resin has a Vicat temperature of 105 to 125 ° C. However, when a copolymer containing a polar functional group is exposed to a high temperature, a cross-linking reaction of the polymer chain occurs due to a side reaction of the polar group, resulting in the formation of a gel-like substance and the molding processability by increasing the viscosity In view of quality and productivity, it was not well received by users from the viewpoint of quality and productivity.

  In addition, the fact that the crosslinking reaction is likely to occur under high-temperature melt residence means that the high molecular weight substance is easily denatured during the molding process, which means that it is difficult to recycle and reuse the resin. For example, when an injection molded product is obtained, sprue and runner portions are generated, and when a molded product is obtained from a biaxially stretched sheet or a foamed sheet, an end material (skeleton) other than the molded product is generated. Generally, these are generally pulverized or cut and then partially mixed with virgin pellets for reuse, or partially mixed with general-purpose resins such as polystyrene for reuse.

However, if the flow characteristics of the resin change due to cross-linking of the high molecular weight during the melt processing, it becomes difficult to reuse the resin, and there is a problem that there is a limit to use as a recycled material for virgin pellets. Further, when blended with virgin pellets, a gel-like substance is mixed, and the appearance and mechanical properties of the molded product are deteriorated and the quality is deteriorated.
In addition, polar functional group-containing copolymers generally have poor compatibility with polystyrene, and even when melt-mixed, gel-like substances are mixed in, resulting in deterioration in mechanical properties and transparency due to differences in refractive index. Since it is also lost, it could not be used as a recycled material by blending with general-purpose PS (polystyrene) or general-purpose HIPS (impact-resistant polystyrene). And since it cannot be used as a recycled material, it has to be treated as industrial waste, and there is a problem in that resources cannot be effectively used and a processing load increases.

In recent years, emphasis has been placed on the effective use of resins, and various recycling laws have been enacted and implemented.
The fact that resin can be recycled, reworked and reused will become an indispensable need in the future resin market. Resin materials that will be developed in the future need to be resins that can be effectively reused, with little molecular weight reduction or monomer generation due to polymer chain scission even after several melt processings. Accordingly, it has been desired to develop a resin material having a higher melt stability than conventional styrene copolymers.
Another problem with the conventional heat-resistant styrenic resins is that the processing condition range during molding is narrow.

  Improving the heat resistance of the copolymer is synonymous with improving the temperature at which the polymer chain starts to flow. Therefore, if it is intended to obtain the same flow characteristics as polystyrene during molding, it is necessary to increase the processing temperature by the amount of improved heat resistance. However, the styrenic copolymer containing a polar functional group does not improve the temperature at which the decomposition start temperature is suitable for the heat resistance. For this reason, there has been a problem that the molding temperature range is narrowed, resulting in a decrease in productivity and quality.

  There is also a method for improving the heat resistance of a styrene resin using a monomer that does not contain a polar functional group. For example, it is known that a copolymer of styrene and α-methylstyrene increases in glass transition temperature according to the content of α-methylstyrene (for example, see Non-Patent Document 1). However, α-methylstyrene has a low ceiling temperature of about 60 ° C., and when attempting to copolymerize styrene and α-methylstyrene using the radical solution polymerization method, which is a typical example of an industrial process, 1) high molecular weight 2) The content of α-methylstyrene in the copolymer is limited and the desired heat resistance cannot be obtained. 3) The thermal stability at the time of melting is poor, and depending on the molding process conditions, Thermal decomposition of the polymer occurs, easily causing monomer components and molecular weight reduction. 4) Since resin pellets are easily yellowed, there are still many problems such as requiring the addition of a colorant depending on the application. There were no examples of industrial use.

On the other hand, since α-methylstyrene can be subjected to living anionic polymerization using a butyllithium initiator, a copolymer of styrene and α-methylstyrene can also be produced by living anionic polymerization (for example, patents). Reference 1).
However, the copolymer obtained based on the known production method of living anionic polymerization has the following problems, and thus has not found sufficient utility value as a resin product. It was not used at all.

That is, the problem is as follows.
1) The produced polymer turns yellow. The yellowness is correlated with the Li content. Therefore, there was a region where the target molecular weight and yellowness could not be balanced. In particular, it has been difficult to use in applications where yellowing is not preferred, such as food packaging applications and optical product applications.
2) The thermal stability at the time of melting of the polymer is poor, and the polymer is decomposed at the time of melting and residence to produce styrene and α-methylstyrene. The amount of the product is more decomposed and produced under the same conditions as compared with polystyrene produced by a widely used radical polymerization method. This fact indicates that the copolymer of styrene and α-methylstyrene has more styrene, α than polystyrene obtained by the radical polymerization method when the molding processing temperature is increased by the amount of heat resistance higher than that of polystyrene. -Means that methylstyrene is generated during molding. Therefore, volatile components such as decomposed styrene and α-methylstyrene are likely to generate silver depending on the molding conditions, and the molecular weight of the copolymer is decreased, and mechanical properties are likely to decrease. Problems such as difficulty in using the product again as a recycled material are easily expected. The fact that the molding process can only be used in a very limited range is of course limited in the applications used, and therefore can be expected to have not been widely accepted industrially.

  Another weakness of polystyrene is that it is poorly weather resistant and is rarely used in applications exposed to sunlight. The cause of poor weather resistance is largely due to the structure of the high molecular weight polymer, so first of all, the development of a styrene copolymer that improved the weather resistance of the high molecular weight polymer itself without relying on weathering agents and UV absorber additives. Was desired.

Japanese Examined Patent Publication No. 6-10219 Journal of Applied Polymer Science, Vol.41, p383 (1990)

  The present invention improves the heat resistance and weather resistance, which were the weak points of SMAA and SMA, while maintaining the excellent properties, dimensional stability and molding processability of conventional styrene resins, and further melt stability and recyclability. Another object of the present invention is to provide a resin composition containing a styrenic copolymer excellent in moldability, strength, and rigidity.

As a result of intensive efforts to solve the above-mentioned problems, the present inventor has obtained a copolymer having a specific physical property value, an isopropenyl aromatic monomer and a vinyl aromatic monomer, and a styrenic polymer. The present inventors have found that a resin composition containing an organic acid can solve the problems of the present invention, and have reached the present invention based on this finding.
That is, the present invention is as follows.

(1) (I) A copolymer containing an isopropenyl aromatic unit represented by the following formula (1) and a vinyl aromatic unit represented by the following formula (2), the isopropenyl aromatic The unit content (A) is 5 to 70 (wt%), and the ratio (Mz / Mw) of the Z average molecular weight (Mz) to the weight average molecular weight (Mw) of the copolymer is 1.4 to 3. A styrene copolymer of 0 and (II) an impact-resistant styrene resin containing a styrene monomer unit containing gel-like rubber particles, and comprising component (I) and component (II) A heat-resistant styrenic resin composition having a weight ratio (I / II) satisfying I / II = 99/1 to 1/99.

(2) The heat-resistant styrene resin composition according to (1) above, wherein the styrene copolymer of the component (I) is obtained by a living polymerization method.
(3)
The content (A) of the isopropenyl aromatic unit in the styrene copolymer of the component (I) is 5 to 95% by weight, and the weight average molecular weight (Mw) and number average molecular weight of the styrene copolymer ( Mn) ratio (Mw / Mn) is in the range of 1.6 to 4.0, and the content (% by weight) of isopropenyl aromatic unit in the styrene copolymer (A) and the styrene copolymer The heat-resistant styrene-based resin composition according to the above (1) or (2), wherein the glass transition temperature (° C.) (Tg) in the coalescence satisfies the relationship of the following formula (a).
Formula (a);
[When 5 ≦ A ≦ 20]
0.12A + 102 ≦ Tg ≦ 0.62A + 102
[When 20 <A ≦ 60]
−5.25 × 10 ⁻⁵ A ³ + 1.09 × 10 ⁻² A ² + 1.72 × 10 ⁻¹ A + 97 ≦ Tg ≦ −5.25 × 10 ⁻⁵ A ³ + 1.09 × 10 ⁻² A ² +1 .72 × 10 ⁻¹ A + 107
[In the case of 60 <A ≦ 95]
1.04A + 73 ≦ Tg ≦ 0.79A + 98

(4) The raw material solution in which the styrenic polymer contains an isopropenyl aromatic monomer represented by the following formula (3) and a vinyl aromatic monomer represented by the following formula (4) is continuously added. A heat-resistant styrenic resin composition as described in any one of (1) to (3) above, which is a copolymer obtained by supplying the polymer into a polymerization reactor.

(5) A heat-resistant foamed sheet obtained from the heat-resistant styrene-based resin composition of (1) to (4) above.
(6) A heat-resistant stretched sheet obtained from the heat-resistant styrene-based resin composition of (1) to (4) above.
(7) A heat-resistant container obtained from the heat-resistant styrene-based resin composition of (1) to (4) above.

  The heat-resistant styrene-based resin composition of the present invention is excellent in heat resistance and weather resistance, which are weak points of polystyrene, while maintaining the dimensional stability and molding processability, which are excellent properties of conventional polystyrene, and particularly melt stable. It has excellent properties in terms of properties, recyclability, strength and rigidity.

Hereinafter, the styrene resin composition according to the present invention will be described in detail.
First, the styrene copolymer of component (I) constituting the heat-resistant styrene resin composition of the present invention will be described.
The styrene copolymer in the present invention comprises an isopropenyl aromatic unit represented by the formula (1) and a vinyl aromatic unit represented by the formula (2).
The copolymer containing an isopropenyl aromatic unit and a vinyl aromatic unit in the present invention is represented by the isopropenyl aromatic monomer represented by the above formula (3) and the above formula (4). A copolymer obtained by polymerizing a vinyl aromatic monomer as a raw material. The hydrocarbon compounds bonded as substituents to the aromatic ring, C n _H 2n _{+ 1 -} refers to a saturated hydrocarbon compound represented by.

  Specific examples of the compound include isopropenyl aromatic monomer such as isopropenylbenzene (α-methylstyrene), isopropenyltoluene, isopropenylethylbenzene, isopropenylpropylbenzene, isopropenylbutylbenzene, There are alkyl-substituted isopropenylbenzenes such as isopropenylpentylbenzene, isopropenylhexylbenzene, and isopropenyloctylbenzene. A preferred monomer is isopropenylbenzene.

  Examples of the vinyl aromatic monomer include styrene, p-methylstyrene, m-methylstyrene, o-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3 Alkyl substituted styrenes such as 1,5-dimethylstyrene, p-ethylstyrene, m-ethylstyrene, o-ethylstyrene, 1,1-diphenylethylene, and the like. A preferred monomer is styrene. These isopropenyl aromatic monomers and vinyl aromatic monomers may be used singly or in combination of two or more. The most preferred combination is a combination of isopropenylbenzene and styrene.

  The content of isopropenyl aromatic units contained in the styrenic copolymer is 5 to 70 wt%. Preferably, it is 7-68 wt%, More preferably, it is 10-65 wt%. When the amount of the isopropenyl aromatic unit is less than 5 wt%, the effect of improving the heat resistance is hardly seen in actual use. On the other hand, if it is more than 70 wt%, thermal decomposition is likely to occur during melt molding, and a large amount of gas is generated during molding or yellowing is likely to occur. In addition, the amount of monomer components accompanying the decomposition increases in the resin, which tends to cause bleeding out on the surface of the molded product.

  In addition to the above monomers, other polymerizable monomers can be used together as long as the object of the present invention is not impaired. Copolymerizable monomers include conjugated diene monomers such as butadiene and isoprene, methacrylic acid alkyl esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate, methyl acrylate, ethyl acrylate, and propyl acrylate. And acrylic acid esters such as butyl acrylate. These monomers are useful for improving or adjusting the impact strength, elongation, chemical resistance, etc. of the resin.

  The styrenic copolymer in the present invention can be preferably produced by a living polymerization method. The living polymerization method includes living anion polymerization, living radical polymerization, and living cationic polymerization, and is not particularly limited, and can be produced by any method. Of these, the living anionic polymerization method is particularly preferable.

  A known method can be used as the living anion polymerization method. For example, an organic lithium compound is used as an initiator, and specifically, n-butyl lithium, sec-butyl lithium, t-butyl lithium, ethyl lithium, benzyl lithium, 1,6-dilithiohexane, styryl lithium, butane Dienylyllithium or the like is used. Of these, n-butyllithium and sec-butyllithium are preferable.

  The polymerization solvent is preferably a hydrocarbon compound that does not contain a heteroatom. Specific examples include aliphatic hydrocarbon compounds such as n-hexane, cyclohexane and heptane, and aromatic hydrocarbon compounds such as benzene, toluene, ethylbenzene and xylene. These hydrocarbon compounds may be used alone or in combination of two or more. A particularly preferred compound is cyclohexane.

  The polymerization temperature is preferably in the range of 40 ° C to 110 ° C. More preferably, it is the range of 50 to 100 degreeC, More preferably, it is the range of 55 to 95 degreeC. When the polymerization temperature is lower than 40 ° C., the reaction rate decreases and there is no practical utility for industrial production. On the other hand, when the polymerization temperature is higher than 110 ° C., the yellowing of the copolymer becomes severe, the weather resistance is lowered, and the thermal stability of the copolymer at the time of melting is also lowered.

  The styrenic copolymer in the present invention can be produced, for example, by a continuous living polymerization method using a completely mixed polymerization reactor. Alternatively, a combination of a completely mixed polymerization reactor and a non-completely mixed polymerization reactor may be used. In particular, in order to obtain a random copolymer, a complete mixing type polymerization reactor is preferable. Complete mixing type polymerization is continuous complete mixing in which the concentration of isopropenyl aromatic monomer, vinyl aromatic monomer, and living copolymer in the living polymerization reaction system is always constant. This refers to a method of polymerization using a type reactor.

  If you want to increase productivity by increasing the monomer concentration in the raw material solution, attach a condenser to the polymerization reactor to efficiently remove the heat of the polymerization reaction, and remove the heat of polymerization by the latent heat of evaporation of the solvent. It is desirable to do. In particular, when cyclohexane (n-hexane may be mixed) is mainly used as a polymerization solvent, since the boiling point is 82 ° C., the polymerization temperature can be easily controlled in the vicinity of 80 ° C. to 90 ° C.

  When using a non-completely mixed tube polymerization reactor, for example, when the ratio L / D of the reactor length (L) to the inner diameter (D) is 1 or more, or when the stirring efficiency is poor, etc. When it is difficult to take a completely mixed state in the reactor, the styrene copolymer of the present invention can be produced by adding a solution of the vinyl aromatic monomer from the middle of the reactor.

  Alternatively, the copolymer of the present invention may be prepared by connecting two or more incompletely mixed polymerizers in series and adding a solution of a vinyl aromatic monomer to the second polymerization reactor after the first polymerization. You can also get

  Furthermore, only the vinyl aromatic monomer is polymerized in the first polymerization reactor, and then the copolymerization of the isopropenyl aromatic monomer and the vinyl aromatic monomer is performed in the second polymerization reactor. It is possible to obtain a block copolymer of a homopolymer and a copolymer of vinyl aromatic units.

  The ratio (Mz / Mw) of the Z-average molecular weight (Mz) to the weight-average molecular weight (Mw) of the styrene copolymer needs to be in the range of 1.4 to 3.0. The range is preferably 1.42 to 2.9, more preferably 1.45 to 2.8. If the Mz / Mw value is less than 1.4, the balance between resin fluidity and mechanical strength is poor, and problems such as difficulty in increasing the draw ratio during biaxial stretching occur. On the other hand, if it exceeds 3.0, the balance between fluidity and thermal decomposability is deteriorated, and it becomes difficult to mold large molded products, thin molded products, and the like.

The Mz / Mw value can be controlled by, for example, polymerizing in a reactor having a polymerization time distribution to broaden the molecular weight distribution, or by melting or solution blending two or more copolymers having different molecular weights. There is a method of decentralization.
The Z average molecular weight (Mz) and the weight average molecular weight (Mw) can be determined by gel conversion using gel permeation chromatography (GPC).

The styrene copolymer of the present invention satisfies the relationship of the following formula (a ′) depending on the range of the content of isopropenyl aromatic units (hereinafter referred to as “% by weight relative to the weight of the styrene copolymer”). It is necessary.
Here, it is necessary that C = 0.12, D = 0.62, E = 0.97, F = 107, G = 1.04, H = 73, I = 0.79, and J = 98. In this case, the formula (a ′) coincides with the above formula (a).

Formula (a ′);
[When 5 ≦ A ≦ 20]
C × A + 102 ≦ Tg ≦ D × A + 102
[When 20 <A ≦ 60]
−5.25 × 10 ⁻⁵ A ³ + 1.09 × 10 ⁻² A ² + 1.72 × 10 ⁻¹ A + E ≦ Tg ≦ −5.25 × 10 ⁻⁵ A ³ + 1.09 × 10 ⁻² A ² +1 .72 × 10 ⁻¹ A + F
[In the case of 60 <A ≦ 95]
G × A + H ≦ Tg ≦ I × A + J
A: Content (% by weight) of isopropenyl aromatic units in the styrene copolymer
B: Glass transition temperature of styrene copolymer (° C)

  In the formula (a ′), preferably C = 0.15, D = 0.58, E = 98, F = 106, G = 1.03, H = 74, I = 0.80, J = 97, More preferably, C = 0.20, D = 0.52, E = 99, F = 105, G = 1.02, H = 75, I = 0.81, and J = 96. When the content of the isopropenyl unit is larger than the upper limit of the range satisfying the formula (a ′), the thermal stability at the time of melting deteriorates, yellowing tends to occur, and the balance between heat resistance and weather resistance deteriorates. Problems arise. On the other hand, if the value is smaller than the lower limit, the heat resistance is not sufficient.

The glass transition temperature in this invention can be calculated | required by DSC, and let the temperature calculated | required by the method shown by JIS-K7121 be a glass transition temperature.
In the application using the styrene copolymer in the present invention, particularly when it is necessary to suppress yellowing, or when it is desired to suppress the amount of the monomer that decomposes when the resin is melt-molded, It is necessary that the styrene copolymer satisfies D = 0.52 in the following formula (b).
Formula (b)
A ≦ 0.0002X ² −0.0017X + D
X: Content of isopropenyl aromatic unit (wt%)
A: Absorbance of styrene copolymer molded product at 305 nm

  Preferably, D = 0.51, more preferably D = 0.50. When it becomes larger than D = 0.52, it becomes a level at which the yellowing of the pellet or the molded product can be clearly confirmed visually. In addition, the generation rate of the monomer decomposed from the high molecular weight body at the time of melting becomes extremely fast, and the amount of monomer remaining in the molded body increases. In particular, during the production of biaxially stretched sheets (OPS) and foamed sheets (PSP) used in the food packaging field, the yellowing of the resin is noticeable and may cause quality problems because the sheet is wound up and collected. is there. Therefore, the user of such an application is particularly sensitive to yellowing of the resin and is regarded as one of important performance requirements.

When the resin composition of the present invention is used as a resin molded product, the values of F, G, H, and J in the following formula (c) are F = -1.92, G = 2.95, and H = 98. It is preferable to use a styrene copolymer having a weight average molecular weight (Mw) satisfying .2 and J = 6.37.
Formula (c)
F × 10 ⁻² A ² + G × 10 ⁻¹ A + H ≦ Mw × 10 ⁻³ ≦ exp (J-2.77 × 10 ⁻² A)
A: Content of isopropenyl aromatic unit in styrene copolymer (wt%)
Mw: weight average molecular weight of the copolymer

  Preferably F = 2.29, G = 2.77, H = 112 and / or J = 6.23, more preferably F = -2.75, G = 2.20, H = 131 and / or. Or, J = 6.13. When the weight average molecular weight is smaller than the values satisfying F = −1.92, G = 2.95, and H = 98.2 in the above formula (c ′), the mechanical strength becomes low and the resin molded body has sufficient performance. As a result, for example, when a molded body is obtained by molding, a problem of cracking tends to occur when the mold is separated from the mold. On the other hand, if it is larger than the weight average molecular weight satisfying J = 6.37 of the above formula (c ′), the fluidity becomes very bad and a large molded product cannot be injection molded.

The bonding mode of the isopropenyl aromatic unit and the vinyl aromatic unit of the styrene copolymer in the present invention is not particularly limited, but the most preferable bonding mode is a copolymer composed of random bonds. Generally, when there are many chains of isopropenyl aromatic units, thermal decomposition tends to occur. Therefore, depending on the application, it is preferable to control the chain of isopropenyl aromatic units to 2 to 4 chains or less.
Even if the vinyl aromatic unit is a chain, there is no fear of particularly impairing the thermal stability. Therefore, the vinyl aromatic unit may have a long chain structure.

  The present inventor has proposed that an AB-type or ABA-type block copolymer in which a long chain of vinyl aromatic units is present at the end of the copolymer molecular chain (A is mainly composed of a vinyl aromatic unit component). Homopolymer component B is a random copolymer component containing isopropenyl aromatic units and vinyl aromatic units), but other properties including heat resistance, thermal stability, mechanical properties and fluidity are random The inventors have found that the homopolymer is very good in compatibility with the homopolymer having the same structure as the vinyl aromatic unit, which is one component of the block, which is equivalent to the coalescence. Taking advantage of this characteristic, when it is desired to reuse the styrene copolymer of the present invention as a recycled material, for example, when it is desired to reuse it by melting and kneading with polystyrene, a copolymer having a polystyrene chain blocked at the polymer chain end of the copolymer is used. Polymers can be used.

  The block chain length of the vinyl aromatic unit is not particularly limited, and preferably, the number average molecular weight of the block chain portion may be in the range of 1000 to 300,000. Moreover, it is preferable that Mw / Mn of the block component which consists of a vinyl aromatic unit exists in the range of 1.0-3.5.

  The ratio (Mz / Mw) of the Z average molecular weight (Mz) to the weight average molecular weight (Mw) of the copolymer having vinyl aromatic units as a block component must be in the range of 1.4 to 3.0. is there. The range is preferably 1.42 to 2.9, more preferably 1.45 to 2.8. When the Mz / Mw value is less than 1.4, the balance between the resin fluidity and the mechanical properties is deteriorated, and it becomes difficult to obtain sufficient performance as a resin molded body. On the other hand, when it exceeds 3.0, the fluidity is deteriorated and it becomes difficult to mold a large molded product, a thin molded product or the like.

  Examples of the method for producing a copolymer having a vinyl aromatic unit as a block component include a batch reactor, a continuous tube reactor, a continuous static mixer reactor, a tank reactor with continuous stirring blades, A homopolymer consisting of vinyl aromatic units is produced in a continuous coil reactor, etc., and then isopropenyl aromatic monomer and vinyl aromatic monomer and living vinyl aroma are placed in a continuous fully mixed reactor. An AB type block copolymer can be obtained by feeding and copolymerizing a homopolymer comprising a group unit. When an ABA type block copolymer is obtained, it can be produced by producing an AB type block copolymer and then living polymerizing vinyl aromatic units in a separate reactor. Or after manufacturing an AB type | mold living copolymer, an ABA type | mold block copolymer can be obtained by adding the bifunctional compound which reacts with a living growth seed | species in another reactor.

  As a result of further earnest studies, the inventor has obtained an isopropenyl aromatic unit represented by the above formula (1) and a vinyl aromatic unit represented by the above formula (2) obtained by a continuous living polymerization method. The composition ratio of the isopropenyl aromatic monomer represented by the formula (3) and the vinyl aromatic monomer represented by the formula (4) in the raw material is continuously determined. Alternatively, a styrene-based copolymer composed of at least two different types of copolymers in the copolymer obtained by intermittently changing the copolymer and supplying it to the polymerization reactor has heat resistance and thermal stability. In addition, the inventors have found that the other properties including mechanical properties and fluidity are equivalent to those of the random copolymer, and that the compatibility with the polymer having a vinyl aromatic unit as a main component is extremely good.

  This suggests that when the molded article of the copolymer is recycled, it can be reused by blending it with a polymer containing vinyl aromatic units as a main component, such as polystyrene, as a recycled material. Yes. The term “different copolymer” as used herein refers to a copolymer having a glass transition temperature different by at least 3 ° C. or more.

  The composition ratio of the isopropenyl aromatic monomer and the vinyl aromatic monomer in the monomer is continuously or intermittently changed and supplied into the polymerization reactor, that is, introduced into the polymerization reaction system. As a result, the composition ratio of each aromatic unit of the resulting copolymer continuously changes, and at least two or more different types are obtained. A copolymer having a constituent composition ratio is obtained in sequence.

  Copolymers having two or more different compositional ratios may be mixed in a solution state in a batch-type tank and then flushed into a tank heated under vacuum to remove the solvent, or The solvent can be removed using an extruder or a kneader and recovered in a pellet state. Alternatively, it is possible to collect the pellets as they are without collecting them in a batch type tank, and to mix and homogenize the pellets in a batch type or continuous type mixing container. Alternatively, the pellets can be made uniform in a mixing container and then melt mixed using an extruder.

  As a specific production example, a reactor in which the component composition ratio of the isopropenyl aromatic monomer (M1) and the vinyl aromatic monomer (M2) is M1 / M2 = 50/50 (wt%) is used as a reactor. After being fed and polymerized, it is switched to a raw material having a different composition ratio, for example, M1 / M2 = 40/60 (wt%), and then introduced into the reactor for polymerization. In this case, the raw material composition was changed intermittently. When polymerized in this way, continuous from the composition of the copolymer obtained by polymerization at M1 / M2 = 50/50 (wt%) to the composition of the copolymer obtained at M1 / M2 = 40/60 (wt%). Copolymers having different composition are obtained in sequence. The obtained copolymer is stirred and mixed in a batch type tank in a solution mixture or in a pellet state, and then melt-kneaded to obtain a copolymer having a certain composition.

  The copolymer obtained by such a method can be considered to be a copolymer composition in which the composition ratio of the isopropenyl aromatic unit component and the vinyl aromatic unit component is different. The copolymer thus obtained is extremely compatible with a homopolymer of vinyl aromatic monomer, and is highly useful as a recycled material because it can maintain transparency without deteriorating mechanical properties. It was found to be a copolymer.

  In the living anion polymerization method, which is a representative example of the method for producing the copolymer of the present invention, the completion of the polymerization reaction is preferably performed when the reaction rate of the vinyl aromatic monomer reaches 99% or more. Group monomers may remain in the reaction system. Termination of the polymerization reaction includes addition of a compound having an oxygen-hydrogen bond such as water, alcohol, phenol or carboxylic acid as a terminator, an epoxy compound, an ester compound, a ketone compound, a carboxylic acid anhydride, or a compound having a carbon-halogen bond. The same effect can be expected. The amount of these additives used is preferably about 10 times the equivalent of the growth species. If the amount is too large, it is not only disadvantageous in terms of cost, but also often mixed with remaining additives.

A living growth species can be used to perform a coupling reaction with a polyfunctional compound to increase the molecular weight of the polymer, and further to make the polymer chain into a branched structure. The polyfunctional compound used for such a coupling reaction can be selected from known ones. Examples of the polyfunctional compound include polyhalogen compounds, polyepoxy compounds, mono- or polycarboxylic acid esters, polyketone compounds, mono- or polycarboxylic acid anhydrides, and the like. Specific examples include silicon tetrachloride, di (trichlorosilyl) ethane, 1,3,5-tribromobenzene, epoxidized soybean oil, tetraglycidyl 1,3-bisaminomethylcyclohexane, dimethyl oxalate, trimellitic acid tri- Examples include 2-ethylhexyl, pyromellitic dianhydride, diethyl carbonate and the like.

  An alkali component derived from an organic lithium compound as a polymerization initiator, for example, lithium oxide or lithium hydroxide can be neutralized and stabilized by adding an acidic compound. Examples of such acidic compounds include a mixture of carbon dioxide gas and water, boric acid, various carboxylic acid compounds, and the like, which can be dissolved in the same solvent as the polymerization solvent and added to the polymer solution after termination of polymerization. In particular, the coloration resistance may be improved by the addition of these.

  After the polymerization is complete, unreacted monomers and solvent are recovered and volatilized and removed from the polymer for reuse. A known method can be used for the volatilization removal. As the devolatilization apparatus, for example, a method of flushing in a vacuum tank and / or a method of heating and evaporating under vacuum using an extruder or a kneader can be preferably used. Although depending on the volatility of the solvent, in general, volatile components such as the solvent and residual monomer are volatilized and removed at a temperature of 180 to 300 ° C. and a degree of vacuum of 100 Pa to 50 KPa.

  It is also effective to connect the devolatilizers in series and arrange them in two or more stages. A method of increasing the volatilization ability of the second-stage monomer by adding water between the first and second stages can also be used. In order to remove the remaining volatile components after removing the volatile components in the flushing tank, an extruder with a vent can be used. The styrenic copolymer from which the solvent has been removed can be finished into pellets by a known method.

  If necessary, the styrene copolymer of the present invention may be added with known compounds used in styrene resins for the purpose of improving thermal, mechanical stability, fluidity and colorability. Examples thereof include primary antioxidants such as 2,6-di-tert-butyl-4-methylphenol, triethylene glycol-bis- [3- (3-tert-butyl-5-methyl-4-hydroxy). Phenyl) propionate], pentaerythritol tetrakis [-(3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) Propionate, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, n-octadecyl 3- (3,5-di-t-butyl) -4-Hydroxyphenyl) propionate, 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenylacryl 2 [1- (2-hydroxy3,5-di-t-pentylphenyl)]-4,6-di-t-pentylphenyl acrylate, tetrakis [methylene 3- (3,5-di-t- Butyl-4-hydroxyphenyl) propionate] methane, 3,9bis [2- {3- (t-butyl-4-hydroxy-5-methylphenyl) propynyloxy} -1,1-dimethylethyl] -2,4 , 8,10-Tetraoxa [5,5] undecane, 1,3,5-tris (3 ′, 5′-di-t-butyl-4′-hydroxybenzyl) -s-triazine-2,4,6 ( 1H, 2H, 3H) -trione, 1,1,4-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 4,4′-butylidenebis (3-methyl-6-tert-butylphenol) Etc.) Include 4,6-3-substituted phenols.

It is also possible to add a phosphorus-based antioxidant, a sulfur-based antioxidant as a secondary antioxidant, a hindered amine stabilizer, and a UV absorber as a weathering agent. In addition, it is also possible to add plasticizers such as mineral oil, lubricants such as long chain aliphatic carboxylic acids and / or metal salts thereof, and organic dyes and organic pigments for improving colorability.

An anthraquinone organic dye for improving the colorability is particularly preferred because it hardly reduces the thermal stability of the copolymer.
Silicone-based, fluorine-based release agents, antistatic agents, etc. can be applied as they are with known techniques used in styrene-based resins. These stabilizers can be used in polymer solutions after polymerization is complete. It can be added and mixed, or it can be melt mixed using an extruder after polymer recovery.

Next, the impact-resistant styrene resin as the component (II) constituting the heat-resistant styrene resin composition of the present invention will be described.
The impact-resistant styrenic resin in the present invention refers to a styrenic resin containing gel rubber particles, and the kind thereof is not particularly limited. The gel rubber particles may be rubber elastic particles such as polybutadiene, polyisoprene, EPDM, etc., having a double bond in the main chain and partially forming a gel-like pair by a crosslinking reaction.
The styrenic resin referred to in the present invention means a homopolymer and / or copolymer containing a styrenic monomer.
Examples of the styrene monomer include styrene, p-methylstyrene, m-methylstyrene, o-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3, Examples include alkyl-substituted styrenes such as 5-dimethylstyrene, p-ethylstyrene, m-ethylstyrene, o-ethylstyrene, and 1,1-diphenylethylene. A preferred monomer is styrene.

A homopolymer containing a styrene monomer refers to a polymer obtained by polymerizing one or more styrene monomers.
Moreover, the copolymer containing a styrene monomer is the styrene monomer described above and a nitrile monomer such as acrylonitrile and methacrylonitrile, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, etc. Of alkyl methacrylate monomers, such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, monomers such as methacrylic acid, acrylic acid, maleic anhydride, N-alkyl substituted maleimide It refers to a copolymer consisting of a combination. Examples thereof include polystyrene, styrene-acrylonitrile copolymer, styrene-methyl methacrylate copolymer, styrene-acrylate copolymer, styrene-methacrylic acid copolymer, styrene-maleic anhydride copolymer, and the like.

  Further, as a method for producing a styrene resin containing gel rubber particles in the present invention, for example, a solution containing a polybutadiene obtained by anionic polymerization or coordination anion polymerization of a butadiene monomer and a styrene monomer In-situ radical polymerization method, or butadiene monomer is pre-manufactured as gel rubber particles by emulsion polymerization method, and then styrene monomer is added and radical emulsion polymerization method And the like.

  The weight ratio of each component of the styrene copolymer (I) and the impact resistant styrene resin (II) is I / II = 99/1 to 1/99. Preferably I / II = 98/2 to 2/98, more preferably I / II = 96/4 to 4/96. When the styrene copolymer (I) is less than 1 wt%, the effect of improving heat resistance cannot be expected. Moreover, when there are more styrene-type copolymers (I) than 99 wt%, the characteristic of styrene-type resin (II) will not express.

The mixing method of the resin composition of the present invention is not particularly limited. Various processing devices such as kneaders, Banbury mixers, mechanical mixing using an extruder, or solution mixing in a solvent can be used.
The heat-resistant styrene resin composition of the present invention is suitable for an injection molded article. In particular, it can be used for structural materials and containers that require heat resistance and high rigidity, molded articles that require weather resistance, and electric lighting covers.

Examples of the present invention will be specifically described below with reference to Examples and Comparative Examples. However, these are examples and do not limit the technical scope of the present invention.
The analysis methods, evaluation methods, and conditions used in the examples and comparative examples are as follows.

[Analysis method]

(1) Molecular weight (Mz, Mw, Mz / Mw)
Two columns (TSKgel SuperHZM-H, 40 ° C.) were connected to HLC-8220 manufactured by Tosoh Corporation, and measurement was performed with a GPC apparatus equipped with an RI detector. The mobile phase was THF. The molecular weight was calculated in terms of polystyrene by creating a calibration curve using polystyrene standard (manufactured by Tosoh Corporation).

(2) Glass transition temperature (Tg)
It calculated | required based on JIS-K-7121 using DSC-7 made from Perkin Elmer. Specifically, the temperature was raised from room temperature to 250 ° C. at 10 ° C./min under nitrogen, then returned to room temperature at 10 ° C./min, and again raised to 250 ° C. at 10 ° C./min. The glass transition temperature measured in the second temperature raising process was defined as Tg.

(3) Composition amount of α-methylstyrene in the copolymer It was determined using NMR (DPX-400) manufactured by BRUKER. ¹ H-NMR of the copolymer was measured, and the peak area ratio of methyl, methylene, and methine was determined from the calculation. A detailed calculation method is shown in FIG.

[Injection molding method]
Molding was performed under the following conditions using an injection molding machine (AUTO SHOT 15A) manufactured by FUNAC. The cylinder temperature was set to 215 ° C., 225 ° C., 230 ° C., and 230 ° C. from the hopper side. The mold temperature was set to 60 ° C., the injection time was 10 seconds, and the cooling time was 20 seconds. The molten resin was filled by applying a pressure 5 MPa higher than the injection pressure at which the resin just fills the mold.
ASTM No. 4 3 mmt dumbbell pieces and strip pieces were respectively molded and used as samples for tensile test, bending test, absorbance measurement, yellowness measurement, Vicat temperature measurement, and weather resistance test.

[Extrusion method] (Blend method of styrene copolymer and styrene-diene block copolymer)
A resin composition was prepared using a 15-mm diameter twin-screw extruder (manufactured by Technobel). The cylinder temperature was 220 ° C. (110 ° C. under the hopper), the screw rotation speed was 200 rpm, and the discharge amount was 1.9 kg / Hr.

[Production of stretched sheet]
A flat plate of 10 cm × 10 cm × 2 mmt was obtained by compression molding. The molding temperature was 240 ° C. Then, it was stretched by a tenter in a biaxial direction in a temperature atmosphere 30 ° C. higher than the glass transition temperature.

[Production of foam sheet]
0.1 part by weight of talc was added to 100 parts by weight of a styrenic resin, introduced into a first stage extruder, thermoplasticized at about 220 ° C., and then injected with about 4% by weight of butane for impregnation. Next, the styrene-based resin foamed sheet was prepared by feeding into a second-stage extruder and extruding a temperature-adjusted viscosity suitable for foaming from a die at about 130 ° C. After fully curing the sheet, its thickness was measured and its performance was evaluated. The average thickness of the styrene resin foam sheet was 2.5 mm.

[Evaluation methods]
(1) Evaluation of thermal stability during melting.
Made by Shimadzu Corporation, using TGA-60 device, sample amount of about 10 mg, nitrogen atmosphere, temperature increased from 50 ° C. at 10 ° C./min, weight is 0.1 wt%, 0.2 wt% relative to initial weight, The temperature at which 0.5 wt% decrease was determined.
(2) Heat resistance (Vicat temperature)
It was determined in accordance with ISO method 306.
(3) Tensile / Bending Test Using an AUTO GRAPH (AG-5000D) manufactured by Shimadzu Corporation, measurement was performed under the following conditions.
Tensile test: Chuck distance 64 mm, Tensile speed 5 mm / min Bending test: Span distance 50 mm, Bending speed 1.3 mm / min

[Production Example 1] Production of Styrene Copolymer (I ₁ ) <Raw Material>
Styrene (St: manufactured by Sumitomo Chemical Co., Ltd.), α-methylstyrene (αMeSt: manufactured by Mitsui Chemicals Co., Ltd.) and cyclohexane (CH: manufactured by Idemitsu Petrochemical Co., Ltd.) of St / αMeSt / CH = 27/18/55 (wt%) After the solution mixed at a ratio is stored in a storage tank and nitrogen bubbling is performed, the solution is passed through a 5 L volume purification tower filled with activated alumina (KHD-24 manufactured by Sumitomo Chemical Co., Ltd.), and t-butylcatechol which is a polymerization inhibitor. Was removed.
<Initiator>
n-Butyllithium (15 wt% n-hexane solution, manufactured by Wako Pure Chemical Industries, Ltd.) was diluted 1/51 times with cyclohexane.
<Stopper>
Methanol (special grade, manufactured by Wako Pure Chemical Industries, Ltd.) was diluted with cyclohexane to a concentration of 3 wt%.

<Production Method> Production of Styrene Copolymer (I ₁ ) The polymerization reactor is equipped with a stirring blade (Max Blend blade manufactured by Sumitomo Heavy Industries) and a condenser, and further, a raw material introduction nozzle, an initiator introduction nozzle and a polymerization solution discharge nozzle. A jacketed 3.4 L reactor (R1) with was used. The outlet of the condenser was sealed with nitrogen gas to prevent air from entering from the outside. The volume of the polymerization solution in the polymerization reactor was controlled to always be 2.1 L. A part of the solution was constantly boiling from the polymerization solution, and the internal temperature was controlled between 82 ° C and 84 ° C. The rotation speed of the stirring blade was 175 rpm. Gear pumps were attached to the raw material inlet and outlet of the polymerization reactor, respectively, and the raw material and the polymerization solution were controlled so that a constant flow rate of 2.1 L / Hr could flow. The initiator solution was introduced into the polymerization reactor at 0.25 L / Hr. The polymerization conditions are shown in Table 1.

The living polymer solution discharged from the polymerization reactor was further led to a polymerization terminator solution inlet through a 10 mm diameter pipe by a gear pump. The length of the pipe from the reactor to the stopper mixing point was about 2 m, and the pipe was kept at 65 to 70 ° C. The stopper solution was introduced into the polymerization reaction solution at a flow rate of 0.1 kg / Hr, and then the polymerization reaction was completely stopped via a 1.2 L capacity static mixer (Sulzer, SMX type). It was. Further, the polymer solution was heated to 260 ° C. with a preheater, and then flushed into a container of about 50 L heated to a setting of 260 ° C. under a reduced pressure of 2 MPa to separate and recover the solvent and unreacted monomers from the polymer. The polymer temperature in the flushing vessel was about 240-250 ° C., and the residence time in the polymer tank was about 20-30 minutes. The polymer from which volatile components were sufficiently removed was then discharged in a rope shape, cooled in water and pelletized with a cutter to recover the polymer.
The living polymer solution was extracted from a pipe in the middle of the place where the polymerization solution was discharged from the polymerization reactor and the place where the stopper was added, and the monomer reaction rate was determined using the living polymer solution. The reaction rate of styrene was 99.9% or more, and the reaction rate of α-methylstyrene was 63%. From this result, the unreacted styrene concentration when the polymerization was stopped was 0.07 wt% or less based on the polymer. Table 2 shows the composition ratio and molecular weight of the obtained pellet copolymer.

[Production Example 2] styrene copolymer (I ₂₎ of the composition of the raw material for manufacturing styrene and α- methylstyrene and cyclohexane (CH), the flow rate to the polymerization reactor of the raw material solution, the polymerization reactor of the initiator solution A styrene copolymer (I ₂ ) was obtained by polymerization under the same conditions and method as in Example 1 except that the flow rate into the interior was set to the conditions shown in Table 1.
Table 2 shows the composition, molecular weight, and the like of the obtained styrene copolymer (I ₂ ).

[Production Example 3] Production of styrene copolymer (I ₃ ) 50 parts of styrene copolymer (I ₁ ) produced in Production Examples 1 and 2 and 50 parts of styrene copolymer (I ₂ ) were extruded. And styrene copolymer (I ₃ ) was produced.
Table 2 shows the composition, molecular weight, and the like of the obtained styrene copolymer (I ₃ ).
[Production Example 4]
As impact-resistant styrene resin (II), PS Japan H8117 was used.

[Comparative Production Example 1]
Polystyrene (GPPS, # 685, manufactured by PS Japan) obtained by radical polymerization was used. Tg was 101 ° C.

[Comparative Production Example 2]
Polystyrene (GPPS, G8102, manufactured by PS Japan) obtained by radical polymerization was used. Tg was 103 ° C.

[Comparative Production Example 3]
Styrene and methacrylic acid copolymer (SMAA, G9001, manufactured by PS Japan) obtained by radical polymerization was used. Tg was 117 ° C.

[Examples 1 to 5]
The styrene polymer (I ₁ ) of Production Example ₁ and the impact-resistant styrenic resin (II) described in Production Example 4 are blended in pellets at the weight ratios shown in Table 3, and the resin is obtained using a twin screw extruder. A composition was obtained.

[Examples 6 to 8]
The styrene polymer (I ₂ ) of Production Example ₂ and the impact-resistant styrenic resin (II) described in Production Example 4 are blended in pellets at the weight ratios shown in Table 3, and the resin is obtained using a twin screw extruder. A composition was obtained.

[Examples 9 to 11]
The styrene polymer (I ₃ ) of Production Example ₃ and the impact-resistant styrene resin (II) described in Production Example 4 are blended in the pellet state at the weight ratio shown in Table 3, and the resin is obtained using a twin-screw extruder. A composition was obtained.
Regarding the thermal stability of the pellets evaluated using the pellets obtained in Examples 1 to 9, temperatures at 0.2 wt%, 0.5 wt%, and 1.0 wt% thermal weight reduction rates were determined using TGA.
Moreover, the heat resistance (Vicat temperature), the tensile physical property, and the bending physical property were evaluated about the test piece obtained by injection-molding a pellet. The results are shown in Table 3.

[Comparative Example 1]
The styrene resin (I) of Comparative Production Example 1 and the impact-resistant styrene resin (II) described in Production Example 4 are blended in pellets at the weight ratios shown in Table 3, and the resin composition is obtained using a twin screw extruder. I got a thing.
Regarding the thermal stability of the pellets, temperatures at 0.2 wt%, 0.5 wt%, and 1.0 wt% thermal weight reduction rates were determined using TGA.
Moreover, the heat resistance (Vicat temperature), the tensile physical property, and the bending physical property were evaluated about the test piece obtained by injection-molding a pellet. The results are shown in Table 3.

[Comparative Examples 2 to 4]
The styrene resin (I) of Comparative Production Example 2 and the impact-resistant styrene resin (II) of Production Example 4 are blended in the pellet state at the weight ratios shown in Table 3, and the resin composition is obtained using a twin screw extruder. I got a thing.
Regarding the thermal stability of the pellets, temperatures at 0.2 wt%, 0.5 wt%, and 1.0 wt% thermal weight reduction rates were determined using TGA.
Moreover, the heat resistance (Vicat temperature), the tensile physical property, and the bending physical property were evaluated about the test piece obtained by injection-molding a pellet. The results are shown in Table 3.

[Comparative Example 5]
The styrene resin (I) of Comparative Production Example 2 and the impact-resistant styrene resin (II) of Production Example 4 are blended in the pellet state at the weight ratios shown in Table 3, and the resin composition is obtained using a twin screw extruder. I got a thing.
Regarding the thermal stability of the pellets, temperatures at 0.2 wt%, 0.5 wt%, and 1.0 wt% thermal weight reduction rates were determined using TGA.
Moreover, the heat resistance (Vicat temperature), the tensile physical property, and the bending physical property were evaluated about the test piece obtained by injection-molding a pellet. The results are shown in Table 3.

  As mentioned above, it turns out that the styrene resin composition of this invention is excellent in both heat resistance and melt stability compared with the conventional polystyrene. From this, it can be said that the resin composition of the present invention is a material that can be easily recycled.

  The heat-resistant styrene-based resin composition of the present invention is superior in heat resistance, melt stability during molding, and recyclability while maintaining the excellent properties of conventional polystyrene, so that the injection molded article, stretched It is suitable for a sheet and a foamed sheet, and in particular, it can be suitably used for a structural material, a container, and electric lighting covers that require heat resistance, high rigidity, and recyclability.

It is a diagram illustrating a way it calculates ^{1 H-NMR} spectrum of a polymer for obtaining a styrene copolymer composition of α- methyl styrene containing in the present invention.

Claims (7)

(I) A copolymer containing an isopropenyl aromatic unit represented by the following formula (1) and a vinyl aromatic unit represented by the following formula (2), the content of the isopropenyl aromatic unit Styrene in which (A) is 5 to 70 (wt%) and the ratio (Mz / Mw) of the copolymer's Z average molecular weight (Mz) to weight average molecular weight (Mw) is 1.4 to 3.0 And (II) an impact-resistant styrene resin containing a styrene monomer unit containing gel rubber particles, and the weight ratio (I) of component (I) to component (II) / II) is a heat-resistant styrenic resin composition satisfying I / II = 99/1 to 1/99.

  2. The heat-resistant styrene resin composition according to claim 1, wherein the styrene copolymer of component (I) is obtained by a living polymerization method. The content (A) of the isopropenyl aromatic unit in the styrene copolymer of the component (I) is 5 to 95% by weight, and the weight average molecular weight (Mw) and number average molecular weight of the styrene copolymer ( Mn) ratio (Mw / Mn) is in the range of 1.6 to 4.0, and the content (% by weight) of isopropenyl aromatic unit in the styrene copolymer (A) and the styrene copolymer The heat-resistant styrenic resin composition according to claim 1 or 2, wherein the glass transition temperature (° C) (Tg) in the coalescence satisfies the relationship of the following formula (a).
Formula (a);
[When 5 ≦ A ≦ 20]
0.12A + 102 ≦ Tg ≦ 0.62A + 102
[When 20 <A ≦ 60]
−5.25 × 10 ⁻⁵ A ³ + 1.09 × 10 ⁻² A ² + 1.72 × 10 ⁻¹ A + 97 ≦ Tg ≦ −5.25 × 10 ⁻⁵ A ³ + 1.09 × 10 ⁻² A ² +1 .72 × 10 ⁻¹ A + 107
[In the case of 60 <A ≦ 95]
1.04A + 73 ≦ Tg ≦ 0.79A + 98 The styrenic polymer continuously polymerizes a raw material solution containing an isopropenyl aromatic monomer represented by the following formula (3) and a vinyl aromatic monomer represented by the following formula (4). The heat-resistant styrenic resin composition according to any one of claims 1 to 3, wherein the heat-resistant styrenic resin composition is a copolymer obtained by being supplied into a vessel.

  A heat-resistant foam sheet obtained from the heat-resistant styrene-based resin composition according to claim 1.   A heat-resistant stretched sheet obtained from the heat-resistant styrene-based resin composition according to any one of claims 1 to 4.   A heat-resistant container obtained from the heat-resistant styrene-based resin composition according to claim 1.

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