JP2005225960A - Rubber-modified styrenic resin composition and molded article obtained by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an inexpensive rubber-modified styrenic resin composition which stably blows parisons and shows an excellent draw-down resistance in blow molding, yields a blow molded article with little nonuniform wall thickness and a good appearance and allows a good recycability of the blur of the molded article occurring in its molding. <P>SOLUTION: The rubber-modified styrenic resin composition contains a rubbery polymer in a matrix polystyrenic resin as dispersion particles. The polystyrenic resin has a weight-average molecular weight of 250,000-300,000 and a Z-average molecular weight of ≥500,000. The ratio of the weight-average molecular weight to the number-average molecular weight (Mw/Mn) is not less than 2.5 and less than 3. The ratio of the Z-average molecular weight to the weight-average molecular weight (Mz/Mw) is not less than 1.9. The average particle size of the dispersion particles is 0.5-5 μm. The amount of a gel in the resin composition is 10-24 wt.% and the amount of methanol solubles is not more than 1.5 wt.% in the resin composition. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a rubber-modified styrenic resin composition suitable for blow molding, and a blow-molded article using the resin composition.

  Conventionally, blow molding has been widely performed as a method for molding a thermoplastic resin. Among these, blow molded products of polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyethylene (PE), and polypropylene (PP) take advantage of their characteristics to provide food / beverages, detergents / hairwashes, chemicals, and industrial use. It is widely used as a container. On the other hand, blow molded products of styrene-based resins have been used in disposable containers and the like by taking advantage of their high rigidity and excellent dimensional stability.

  In recent years, not only in the above containers, but also in the manufacture of large molded products such as automobile parts such as spoilers, frames for arcade game machines, bathroom ceilings and walls, and bathroom equipment such as bathroom vanities. Blow molding is performed. Such a large molded article is usually required to have impact resistance performance as a structural component rather than the transparency required as the performance of the container. Therefore, rubber-modified styrene resins such as acrylonitrile-butadiene-styrene copolymer (ABS) and rubber-modified polystyrene (HIPS) having high impact resistance are usually used for large molded articles.

  In blow molding, compressed gas is blown into a hollow preform (parison) of a molten or softened resin to inflate the parison to the inner wall of the mold and simultaneously cool to obtain a hollow product. According to blow molding, a large molded product can be obtained with a small clamping force. Further, since blow molding can be performed at a low pressure, the required mold strength is lower than that of injection molding. Therefore, blow molding is an excellent molding method that can produce a mold at a lower cost than that of injection molding and can obtain a large molded product.

  However, when a large molded product is manufactured by blow molding, the parison cannot withstand its own weight and draw-down (resin drooping due to its own weight) may occur, resulting in uneven thickness of the molded product. If the wall thickness is not uniform, the impact resistance may decrease. Further, if the thickness is non-uniform, when the molded product is colored, unevenness may easily occur in the color of the molded product. As the molded product to be manufactured increases in size, the thickness of the molded product tends to become non-uniform.

  On the other hand, a method of increasing the amount of the rubber-like polymer to be blended with the styrene resin and improving the impact resistance can be considered. However, in this method, the drawdown of the parison is further increased, and it may be more difficult to make the thickness of the molded product uniform.

  Further, as a method for suppressing the drawdown and making the thickness of the molded product uniform, a method of increasing the molecular weight of the styrene resin to obtain a high melt viscosity can be considered. However, in this method, since the fluidity of the resin is lowered, it may be difficult to discharge the parison. When the parison is discharged, abnormal flow such as scab or melt fracture occurs, and the parison becomes unstable and is obtained. The surface of the blow molded product may become rough.

  On the contrary, as a method for improving the fluidity of the resin and stabilizing the discharge of the parison, there is a method of adding a plasticizer typified by mineral oil. However, in this method, since the melt viscosity is lowered, the drawdown of the parison becomes large, and the thickness of the molded product may become uneven.

  As a method for improving the fluidity of the resin and stabilizing the discharge of the parison, a method of increasing the processing temperature is generally used. However, this method also decreases the melt viscosity of the resin, increases the drawdown of the parison, and may result in uneven thickness of the molded product. Furthermore, this method tends to lengthen the molding cycle due to the longer cooling time.

  In addition, as a method for suppressing the drawdown of the resin to which the plasticizer is added, there is a method of lowering the processing temperature and increasing the melt viscosity of the resin. However, in this method, as a matter of course, since the fluidity of the resin is lowered, the discharge of the parison may be difficult or unstable.

  As described above, in large blow molding, conflicting resin melt viscosity characteristics are required for parison ejection stability, drawdown resistance, and uniform blow molded product thickness. A rubber-modified styrenic resin composition that can be satisfied is desired.

  On the other hand, in large blow molding, burrs may occur in the resulting molded product. In the case of a large molded product, about 50% of the resulting blow molded product may be burrs. Therefore, although burr reduction can be achieved by molding conditions and mold design, it is desired to reuse the burr from the economical viewpoint. However, as described above, in large blow molding, a large change occurs in moldability due to the melt viscosity of the resin. Therefore, it is difficult to reuse the burrs whose melt viscosity has decreased due to the heat history during molding. There is a demand for a resin composition that can easily reuse burrs even in large blow molding.

  In Patent Document 1, as a styrene copolymer having sufficient melt viscoelasticity and particularly useful as a blow molding material, 100 to 40% by weight of a styrene compound unit (A), acrylonitrile, (meth) acrylic acid 0 to 60 wt% of other copolymerizable compound units (B) such as esters, and a specific reactive carboxylic acid metal complex salt unit (C) per 100 parts by weight of (A) and (B) in total Discloses a styrene-based copolymer obtained by copolymerization in a proportion of 0.001 to 2 parts by weight. However, it cannot be said that this styrene copolymer has sufficient performance for molding a large blow molded article. Further, since this styrene copolymer uses a reactive carboxylic acid metal complex salt, it is more expensive than a normal styrene resin.

In addition, Patent Document 2 discloses a matrix-modified rubber-modified polystyrene resin for blow molding excellent in extrusion characteristics for parison formation, processability peculiar to blow molding such as drawdown resistance, and thickness uniformity. The weight average molecular weight Mw is 200 to 350,000, the ratio Mw / Mn between the weight average molecular weight and the number average molecular weight is 3.0 or more, and the median diameter D ( μm) is 2.0 to 8.0 and the gel content is GC (wt%), and the formula ln (GC) + 0.348 × D ≧ 4.37
A rubber-modified polystyrene resin satisfying the above relationship is disclosed. Patent Document 2 describes that the gel content of the rubber-modified polystyrene resin is preferably 10 wt% or more in terms of impact resistance. However, in this rubber-modified polystyrene resin, the discharge of the parison may become unstable, and it cannot be said that the appearance of the resulting blow molded product is good.

  Moreover, in the Example of patent document 2, the thickness uniformity is evaluated by a rectangular parallelepiped blow molded product of length × width × height = 1200 × 800 × 50 mm. In recent years, as a large-sized molded article using a styrene-based resin, a molded article having a long side of 150 cm (1500 mm) or more, such as a bathroom ceiling or wall, and a good appearance are often desired. . In the rubber-modified polystyrene resin disclosed in Patent Document 2, it is not always possible to obtain a large-sized molded product having a long side of 150 cm (1500 mm) or more and a good appearance.

As described above, it cannot always be said that a rubber-modified styrene-based resin composition that can sufficiently cope with a large blow molded article desired in recent years has been obtained, and furthermore, burrs generated during molding can be easily reused. It cannot be said that a rubber-modified styrenic resin composition that can be obtained is obtained.
Japanese Patent Laid-Open No. 10-17620 JP 2002-97340 A

  The object of the present invention is that the discharge state of the parison at the time of blow molding is stable, excellent in draw-down resistance, the uneven thickness of the resulting blow molded product is small, the appearance is good, and molding that occurs during molding Another object of the present invention is to provide a low-cost rubber-modified styrene resin composition for blow molding, which is excellent in recyclability of products, and a blow-molded article using the rubber-modified styrene resin composition.

The present invention is a rubber-modified styrene-based resin composition containing a rubber-like polymer as dispersed particles in a polystyrene-based resin as a matrix,
The polystyrene resin has a weight average molecular weight (Mw) of 250,000 to 300,000, a Z average molecular weight (Mz) of 500,000 or more, and a ratio (Mw / Mn) between the weight average molecular weight and the number average molecular weight. 2.5 or more and less than 3, the ratio (Mz / Mw) of the Z average molecular weight to the weight average molecular weight is 1.9 or more,
The average particle size of the dispersed particles is 0.5 μm to 5 μm,
The amount of gel in the resin composition is 10 wt% to 24 wt%,
The present invention relates to a rubber-modified styrenic resin composition, wherein the methanol-soluble component in the resin composition is 1.5% by weight or less.

The present invention also includes the rubber-modified styrene resin composition, a phosphorus processing stabilizer, and a phenol processing stabilizer.
The total content of the phosphorus processing stabilizer and the phenol processing stabilizer is 0.2 to 1 part by weight with respect to 100 parts by weight of the rubber-modified styrenic resin composition,
The present invention relates to a rubber-modified styrenic resin composition in which the content ratio (mass basis) of the phenol-based processing stabilizer to the phosphorus-based processing stabilizer is 0.5 to 2 (phenol-based processing stabilizer / phosphorous-based processing stabilizer).

  The present invention also relates to the above rubber-modified polystyrene resin composition for blow molding.

  Moreover, this invention relates to the molded article obtained by blow-molding said rubber-modified polystyrene-type resin composition.

  The present invention also relates to a molded product obtained by blow molding a rubber-modified polystyrene resin composition containing burrs generated in a molded product obtained by blow molding the rubber-modified polystyrene resin composition.

  The rubber-modified styrene resin composition of the present invention has a weight average molecular weight (Mw) of 250,000 to 300,000, a Z average molecular weight (Mz) of 500,000 or more, and a weight average of the polystyrene resin as a matrix. The ratio of the molecular weight to the number average molecular weight (Mw / Mn) is 2.5 or more and less than 3, and the ratio of the Z average molecular weight to the weight average molecular weight (Mz / Mw) is 1.9 or more. The average particle size of the polymer is 0.5 μm to 5 μm, the gel amount in the resin composition is 10% by weight to 24% by weight, and the methanol soluble content in the resin composition is 1.5% by weight. It is as follows. Such a rubber-modified styrenic resin composition of the present invention has a stable parison discharge state at the time of blow molding, particularly in large-scale blow molding, is excellent in drawdown resistance, and the resulting blow molded product has uneven thickness. There are few, and an external appearance state is favorable. Moreover, the rubber-modified styrenic resin composition of the present invention is low in cost.

  Further, 0.2 to 1 part by weight of the total amount of the phosphorus processing stabilizer and the phenol processing stabilizer is 100 to 100 parts by weight of the rubber-modified styrene resin composition, and the phenol processing for the phosphorus processing stabilizer. Stabilizer content ratio (mass basis) 0.5 to 2 (phenolic processing stabilizer / phosphorous processing stabilizer) The moldability can be maintained, and the impact resistance of the molded product obtained can be sufficiently suppressed from being lowered.

  Here, “large blow molding” refers to extrusion direct blow molding in which the obtained molded product has a long side of 100 cm or more.

  The rubber-modified styrene resin composition of the present invention contains a rubbery polymer as dispersed particles in a polystyrene resin as a matrix.

  The matrix polystyrene resin is a homopolymer of a styrene monomer, a copolymer of two or more styrene monomers, or a copolymer of one or more styrene monomers and one or more other monomers. It is. Examples of the styrene monomer include alkyl-substituted styrenes such as styrene, α-methylstyrene, and p-methylstyrene.

  Examples of the rubbery polymer include polybutadiene, polyisoprene, styrene-butadiene copolymer, styrene-isoprene copolymer, acrylonitrile-butadiene copolymer, ethylene-α-olefin copolymer, silicone rubber, acrylic rubber, Examples thereof include a butadiene- (meth) acrylic acid ester copolymer, a styrene-butadiene block copolymer, a hydrogenated styrene-butadiene block copolymer, and an ethylene ionomer. As the polybutadiene, either a high cis polybutadiene having a high cis content or a low cis polybutadiene having a low cis content can be used. The styrene-butadiene copolymer preferably has a styrene content of 5 to 60%.

  In the rubber-modified styrene resin composition of the present invention, the weight average molecular weight (Mw) of the matrix polystyrene resin is 250,000 to 300,000, and the Z average molecular weight (Mz) is 500,000 or more.

  When the weight average molecular weight (Mw) of the matrix polystyrene resin is less than 250,000, sufficient drawdown resistance cannot be obtained. On the other hand, if the weight average molecular weight (Mw) of the polystyrene-based resin of the matrix exceeds 300,000, an abnormal flow in which fine wrinkles are generated on the parison surface during the parison discharge is likely to occur. A good molded product cannot be obtained.

  When the Z-average molecular weight (Mz) of the polystyrene-based resin of the matrix is less than 500,000, sufficient draw-down resistance cannot be obtained, and the thickness of the resulting molded product is not uniform particularly in large blow molding. The Z-average molecular weight (Mz) of the matrix polystyrene resin is more preferably 540,000 or more. The upper limit of the Z average molecular weight (Mz) of the matrix polystyrene resin is not particularly limited, but is usually about 1 million.

  The larger the weight average molecular weight (Mw) and the Z average molecular weight (Mz) of the matrix polystyrene resin, the higher the melt viscosity, the better the drawdown resistance, and the more uniform the thickness of the resulting blow-molded product. is there. On the other hand, when the weight average molecular weight (Mw) of the matrix polystyrene resin increases, the melt viscosity increases, the parison ejection becomes unstable, and abnormal flow tends to occur. From the contradictory relationship between the weight average molecular weight (Mw) and the Z average molecular weight (Mz), it is important to set each of the above predetermined ranges.

  In general, in order to increase the melt viscosity in order to improve the drawdown resistance, the matrix is increased in molecular weight. However, in that case, the number average molecular weight (Mn), weight average molecular weight (Mw) and Z average molecular weight (Mz) of the polystyrene-based resin of the matrix are all increased, and sufficient parison ejection performance cannot be obtained. Therefore, in the present invention, the polystyrene-based resin of the matrix needs to have a desired molecular weight distribution.

  In the rubber-modified styrene resin composition of the present invention, the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the matrix polystyrene resin is 2.5 or more and less than 3. The ratio (Mz / Mw) between the Z average molecular weight (Mz) and the weight average molecular weight (Mw) is 1.9 or more.

  The ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polystyrene-based resin of the matrix is an index indicating the discharge performance of the parison. The larger the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the matrix polystyrene resin, the higher the melt viscosity and the better the drawdown resistance. The thickness tends to be uniform, but on the other hand, the parison discharge becomes unstable and abnormal flow tends to occur.

  If the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the polystyrene-based resin of the matrix is less than 2.5, sufficient drawdown resistance cannot be obtained, and particularly large blow In molding, the thickness of the resulting molded product becomes non-uniform. On the other hand, when the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the matrix polystyrene resin is 3 or more, the discharge of the parison becomes unstable and abnormal flow tends to occur. In particular, in large blow molding, a molded product having a sufficiently good appearance cannot be obtained.

  When the ratio (Mw / Mn) to the number average molecular weight (Mn) is increased with the weight average molecular weight (Mw) in a specific range, the melt viscosity is increased and the drawdown resistance is improved. Discharge tends to be unstable, and there is a tendency that a blow-molded product with a good appearance cannot always be obtained.

  The ratio (Mz / Mw) between the Z-average molecular weight (Mz) and the weight-average molecular weight (Mw) of the matrix polystyrene resin is an index indicating the drawdown resistance and the thickness uniformity of the molded product obtained. The larger the ratio (Mz / Mw) between the Z-average molecular weight (Mz) and the weight-average molecular weight (Mw) of the matrix polystyrene resin, the better the drawdown resistance and the more uniform the thickness of the resulting blow-molded product. Tend.

  If the ratio (Mz / Mw) between the Z average molecular weight (Mz) and the weight average molecular weight (Mw) of the polystyrene-based resin of the matrix is less than 1.9, sufficient drawdown resistance cannot be obtained, and particularly large blow In molding, the thickness of the resulting molded product becomes non-uniform. The ratio (Mz / Mw) between the Z average molecular weight (Mz) and the weight average molecular weight (Mw) of the matrix polystyrene resin is more preferably 2.1 or more. The upper limit of the ratio (Mz / Mw) between the Z-average molecular weight (Mz) and the weight-average molecular weight (Mw) of the matrix polystyrene resin is not particularly limited, but is usually about 5.0.

  The number average molecular weight (Mn), weight average molecular weight (Mw), and Z average molecular weight (Mz) referred to in the present invention are values determined by gel permeation chromatography (GPC method). Specifically, using a RI detector (differential refraction detector), two Tosoh, Tsk-gel6000HXL and 4000HXL (both 30 cm in length) as a column, tetrahydrofuran as a solvent, a measurement temperature of 40 ° C., The measurement is performed under the conditions of a concentration of 0.2% by weight of the solution to be measured, an injection amount of 0.1 ml, and a flow rate of 1 ml / min. For the calculation of the molecular weight, a straight line was drawn between the rise time of the peak of the obtained chromatograph and the time corresponding to the molecular weight of 2000, and the standard enclosed with the chromatograph was created using standard polystyrene. This is done using a calibration curve.

  In the rubber-modified styrenic resin composition of the present invention, the average particle size of dispersed particles (rubber-like polymer) is 0.5 μm to 5 μm. Even if the average particle diameter of the dispersed particles is less than 0.5 μm or exceeds 5 μm, the impact resistance improving effect by the dispersed particles cannot be sufficiently obtained. The average particle size of the dispersed particles is more preferably 1.5 μm or more. The average particle diameter of the dispersed particles is more preferably 4 μm or less.

  The average particle diameter referred to in the present invention is a particle diameter value of an integrated volume of 50% obtained by a laser diffraction light scattering method. Specifically, a rubber-modified styrenic resin composition is dissolved in methyl ethyl ketone to prepare a sample solution containing dispersed particles having a concentration of 1% by weight. Using this sample solution, for example, SALD1100 manufactured by Shimadzu Corporation is used. To measure.

  The average particle diameter of the dispersed particles (rubber-like polymer) can be adjusted by, for example, a method of adjusting a shearing force applied to the rubber-like polymer in a stage where the rubber-like polymer particles are produced, that is, a so-called phase inversion stage. it can. The shearing force in the phase inversion stage can be adjusted by, for example, a method of dynamically adjusting the number of stirrings in the reaction tank or a method of adjusting the ratio of the viscosity of the rubber-like polymer to the viscosity of the polymerization solution.

  The rubber-modified styrenic resin composition of the present invention has a gel content, that is, a gel amount of 10 wt% to 24 wt%. When the gel amount in the resin composition is less than 10% by weight, the impact resistance of the resulting blow-molded product is lowered. The amount of gel in the resin composition is more preferably 12% by weight or more. On the other hand, if the amount of gel in the resin composition exceeds 24% by weight, sufficient draw-down resistance cannot be obtained, and the thickness of the resulting molded product is not uniform particularly in large blow molding. The amount of gel in the resin composition is more preferably 20% by weight or less.

  The gel amount referred to in the present invention is a weight ratio of soft component particles (gel content) in the rubber-modified polystyrene resin composition, and can be measured by the following method.

  0.5 g of a rubber-modified styrene resin composition is weighed and dissolved in 50 ml of a mixed solvent of methyl ethyl ketone / methanol [methyl ethyl ketone / methanol = 10/1 (volume ratio)] at room temperature (about 23 ° C.). Next, the insoluble matter at the time of dissolution is isolated by centrifugation, and the obtained insoluble matter is dried and its weight is measured. And content of a soft component particle | grain is calculated | required by the following formula.

Gel amount = (W ₁ /0.5)×100 (% by weight)
Here, W ₁ represents the weight (g) of the dried insoluble matter.

  The amount of gel in the rubber-modified styrenic resin composition can be adjusted by, for example, the amount of rubber-like polymer used in the production of the rubber-modified styrenic resin composition. It can also be adjusted by adjusting the degree of crosslinking and particle size of the rubbery polymer in the resin composition.

  The soft component particles have a structure in which polystyrene is occluded in a rubber-like polymer, and generally include a so-called salami structure and a single occlusion structure.

  The rubber-modified styrenic resin composition of the present invention has a methanol-soluble content of 1.5% by weight or less (including 0% by weight). If the methanol-soluble component in the resin composition exceeds 1.5% by weight, sufficient draw-down resistance cannot be obtained, and the thickness of the resulting molded product is not uniform particularly in large blow molding.

  The methanol-soluble matter referred to in the present invention is measured by the following method.

  1 g of the rubber-modified styrene resin composition is weighed and dissolved in 10 g of methyl ethyl ketone. Next, it is put into 500 g of methanol, and methanol insoluble matter is precipitated. Next, the methanol-insoluble matter (precipitate) is separated by filtration, and its weight is measured. And methanol soluble part is calculated | required by the following formula.

Methanol-soluble content = (1-W ₂ ) / 1 × 100 (% by weight)
Here, W ₂ represents the weight (g) of insoluble matter in methanol.

  The methanol-soluble component depends on the low molecular weight component present in the rubber-modified styrenic resin composition. The methanol-soluble component in the rubber-modified styrene resin composition can be adjusted by, for example, a method of adjusting the content of styrene dimer or styrene trimer by a known method in the production stage. Moreover, it can adjust also by the method of adjusting the addition amount of additives, such as a plasticizer.

  In the present invention, it is preferable to add a phosphorus processing stabilizer and a phenol processing stabilizer to the rubber-modified styrene resin composition as described above. By adding a phosphorus processing stabilizer and a phenol processing stabilizer, it is possible to maintain a sufficiently stable formability even in the case of reusing burr of a molded product that occurs during molding in large blow molding, Moreover, the fall of the impact resistance performance of the obtained molded article can fully be suppressed.

  Phosphorus processing stabilizers include 6- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4,8,10-tetra-tert-butyldibenzo [d, f ] [1.3.2] Dioxaphosphepine, tris (2,4-di-tert-butylphenyl) phosphite and the like. A phosphorus processing stabilizer may use 1 type, or may use 2 or more types together.

  Phenol processing stabilizers include n-octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, triethylene glycol-bis [3- (3-tert-butyl-4-hydroxy -5-methylphenyl) propionate], 2-tert-butyl-6- (3-tert-butyl-5-methyl-2-hydroxybenzyl) -4-methylphenyl acrylate, 2,4-di-tert-amyl- Examples include 6- (3,5-di-tert-amyl-2-hydroxy-α-methylbenzyl) phenyl acrylate. Phenol-based processing stabilizers include, among others, 2-tert-butyl-6- (3-tert-butyl-5-methyl-2-hydroxybenzyl) -4-methylphenyl acrylate, 2,4-di-tert-amyl -6- (3,5-di-tert-amyl-2-hydroxy-α-methylbenzyl) phenyl acrylate is preferred. A phenol type processing stabilizer may use 1 type, or may use 2 or more types together.

  In the present invention, the total content of the phosphorus processing stabilizer and the phenol processing stabilizer is 0.2 to 1 part by weight with respect to 100 parts by weight of the rubber-modified styrene resin composition. Molded product produced during blow molding when the total content of the phosphorus processing stabilizer and the phenol processing stabilizer is 0.2 parts by weight or more with respect to 100 parts by weight of the rubber-modified styrenic resin composition. When the burr is reused, the occurrence of drawdown of the parison can be more sufficiently suppressed, molding can be performed more stably, and a molded product having higher impact resistance can be obtained. The total content of the phosphorus processing stabilizer and the phenol processing stabilizer is preferably 0.5 parts by weight or more with respect to 100 parts by weight of the rubber-modified styrenic resin composition. On the other hand, even if a phosphorus-based processing stabilizer and a phenol-based processing stabilizer are added in an excessive amount to the rubber-modified styrenic resin composition as described above, the improvement effect tends not to be improved at the added amount ratio. Therefore, from the viewpoint of cost, the total content of the phosphorus-based processing stabilizer and the phenol-based processing stabilizer is preferably 1 part by weight or less with respect to 100 parts by weight of the rubber-modified styrenic resin composition. . The total content of the phosphorus processing stabilizer and the phenol processing stabilizer is more preferably 0.8 parts by weight or less with respect to 100 parts by weight of the rubber-modified styrenic resin composition.

  In the present invention, the content ratio (mass basis) of the phenol processing stabilizer to the phosphorus processing stabilizer is 0.5 to 2 (phenol processing stabilizer / phosphorus processing stabilizer). By setting the content ratio of the phenol-based processing stabilizer to the phosphorus-based processing stabilizer within the above range, it is possible to achieve both a high level of stability during molding and a reduction in impact strength of the resulting molded product. it can. The content ratio (mass basis) of the phenol-based processing stabilizer to the phosphorus-based processing stabilizer is preferably 0.7 or more. Moreover, it is preferable that the content ratio (mass reference | standard) of the phenol type processing stabilizer with respect to a phosphorus type processing stabilizer is 1.5 or less.

  The rubber-modified styrenic resin composition of the present invention may contain other additives such as a lubricant, an antistatic agent, an antioxidant, a heat stabilizer, an ultraviolet absorber, a pigment, and a dye as necessary. Good. Furthermore, a plasticizer such as mineral oil may be added to the rubber-modified styrene resin composition of the present invention within the scope of the present invention.

  The rubber-modified styrenic resin composition of the present invention can be produced, for example, by a continuous bulk polymerization method, a continuous solution polymerization method, a bulk-suspension polymerization method, or the like.

  The reaction vessel used for the polymerization is not particularly limited, and examples thereof include a complete mixing type reaction vessel, a flow type reaction vessel, and a circulation type reaction vessel. There may be two or more reaction vessels.

In order to obtain a rubber-modified styrenic resin composition having a desired molecular weight by these polymerization methods,
(i) providing a polymerization temperature distribution in the polymerization tank during production;
(ii) using a polyfunctional radical initiator during production;
(iii) copolymerizing a styrenic compound and a polyfunctional monomer during production;
(iv) It is possible by using a molecular weight modifier during production.

  Examples of the polyfunctional radical initiator include 1,1-bis (tert-butylperoxy) cyclohexane, 1,1-bis (tert-hexylperoxy) cyclohexane, 1,1-bis (tert-butylperoxy) 3,3. , 5-trimethylcyclohexane, 2,2-bis (4,4-di-tert-butylperoxycyclohexyl) propane, and the like.

  Examples of the polyfunctional monomer include divinylbenzene, dimethacrylates, diacrylates, triesters, and the like. Examples of dimethacrylates include ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, and polyethylene glycol dimethacrylate. Examples of diacrylates include polyethylene glycol diacrylate and 1,6-hexanediol diacrylate. Examples of triesters include trimethylolpropane trimethacrylate.

  Examples of the molecular weight modifier include α-methylstyrene dimer, n-dodecyl mercaptan, tert-dodecyl mercaptan, and the like.

  Also, a rubber-modified styrenic resin composition having a desired molecular weight can be produced by, for example, producing rubber-modified styrenic resin compositions having different molecular weights in two or more reaction vessels and finally mixing them. Can do.

  The rubber-modified styrenic resin composition of the present invention may be a blend of one or more styrenic resin compositions. The blending method is not particularly limited, and examples thereof include a method in which re-granulation is performed once by an extruder, a method in which two or more kinds of pellets are mixed well in advance, and the mixture is directly charged into a processing machine.

  The large blow molding referred to in the present invention is extrusion direct blow molding. The parison discharge method includes a continuous extrusion method and an intermittent extrusion method. In particular, in order to obtain a large molded product, one employing an intermittent extrusion type accumulator system is preferable. Molding conditions such as extrusion temperature can be appropriately determined according to the properties of the rubber-modified styrene resin composition used.

  According to the present invention, it is possible to obtain a blow molded product having a good quality with a long side of 100 cm or more, and further to obtaining a blow molded product with a good quality having a long side of 150 cm or more.

  In addition, as described above, the rubber-modified styrenic resin composition of the present invention to which a predetermined amount of a phosphorus-based processing stabilizer and a phenol-based processing stabilizer are added can reuse the burr of a molded product that is generated during molding.

  In that case, the burr can be used directly after pulverization, but it can also be used after the burr is once melted with an extruder or the like to produce pellets. In this case, the molding conditions such as the extrusion temperature can be appropriately determined according to the properties of the rubber-modified styrenic resin composition used.

  Note that a molded product can be obtained by blow molding only burrs, or a molded product can be obtained by blending burrs with an unused rubber-modified styrene resin composition and then blow molding them.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited at all by these Examples.

  The obtained rubber-modified styrenic resin composition and molded product were measured and evaluated for physical properties and the like as follows.

[Number average molecular weight, weight average molecular weight and Z average molecular weight of polystyrene resin]
The rubber-modified styrenic resin composition was dissolved in tetrahydrofuran so as to have a concentration of 0.2% by weight, and the insoluble matter at the time of dissolution was centrifuged using a centrifuge, and the supernatant was prepared as a sample solution. And using Tosoh's GPC8220 equipped with RI detector (differential refraction detector), using Tosoh's Tsk-gel G6000HXL and G4000HXL (both 30cm in length), measuring temperature 40 ° C, sample solution The molecular weight was measured under the conditions of an injection volume of 0.1 ml and a flow rate of 1 ml / min. A straight line is drawn between the rise time of the peak of the obtained chromatograph and the time corresponding to a molecular weight of 2000, and the number average molecular weight (Mn), the weight average molecular weight (Mw) of the portion surrounded by the chromatograph and Z average molecular weight (Mz) was calculated. The molecular weight was calculated using a standard calibration curve created using standard polystyrene.

[Amount of gel in rubber-modified styrenic resin composition]
0.5 g of a rubber-modified styrene resin composition was weighed and dissolved in 50 ml of a mixed solvent of methyl ethyl ketone / methanol [methyl ethyl ketone / methanol = 10/1 (volume ratio)] at room temperature (about 23 ° C.). Next, the insoluble matter at the time of dissolution was isolated by centrifugation, and the obtained insoluble matter was dried and its weight was measured. And the gel amount was calculated | required by the following formula.

Gel amount (% by weight) = (W ₁ /0.5)×100
Here, W ₁ represents the weight (g) of the dried insoluble matter.

[Average particle diameter of dispersed particles]
A rubber-modified styrenic resin composition was dissolved in methyl ethyl ketone to prepare a sample solution containing dispersed particles having a concentration of 1% by weight. Then, using this sample solution, the average particle diameter of the dispersed particles was measured using SALD1100 manufactured by Shimadzu Corporation.

[Methanol-soluble matter in rubber-modified styrenic resin composition]
1 g of the rubber-modified styrene resin composition was weighed and dissolved in 10 g of methyl ethyl ketone, and then placed in 500 g of methanol to precipitate methanol-insoluble matter. Next, methanol-insoluble matter (precipitate) was separated by filtration, and its weight was measured. And the methanol soluble part was calculated | required by the following formula.

Methanol-soluble component (% by weight) = (1-W ₂ ) / 1 × 100
Here, W ₂ represents the weight (g) of insoluble matter in methanol.

[Drawdown resistance]
Using a sheet extruder having an extruder with a screw diameter of 40φ, a molten resin (rubber-modified styrene resin composition from a die having a die width of 400 mm and a lip opening of 1.3 mm at a cylinder temperature of 220 ° C. and an extrusion rate of 310 g / min. Product) was extruded. Then, the time from the start of extrusion until the molten resin hangs down 80 cm below the die was measured. It shows that it is excellent in the drawdown resistance, so that this value is large.

[Uneven thickness of molded product]
Using a NB3B type direct blow molding machine (screw diameter = 50 mm, die diameter / core diameter = 26 mm / 25 mm) and round bottle mold (diameter 72 mm × height 164 mm) manufactured by Nippon Steel Works, Ltd., the cylinder temperature 210 The rubber-modified polystyrene resin composition was directly blow-molded under the conditions of ° C., extrusion rate 10 kg / hr, air blowing 10 sec, and exhaust 3 sec.

  The thickness distribution around the bottle at 80 mm from the bottom of the obtained molded product was measured at 10 mm intervals. And the average thickness was calculated | required and the uneven thickness property was calculated | required by the following formula from the average thickness, the maximum thickness, and the minimum thickness.

Unevenness (%) = (maximum thickness−minimum thickness) / average thickness × 100
The uneven thickness of the molded product was evaluated according to the following criteria.

○: Uneven thickness less than 20%,
X: Uneven thickness 20% or more.

[Surface appearance]
The surface of the blow molded product produced in the same manner as the molded product used for the evaluation of uneven thickness was visually observed and the surface appearance was evaluated according to the following criteria.

○: No bad appearance in rough state such as streaks or wrinkles,
X: Appearance defect in rough state such as streaks and wrinkles.

[Impact resistance (Izod impact strength)]
A test piece was molded with an injection molding machine FE80 manufactured by Nissei Plastic Industry Co., Ltd. And using this test piece, Izod impact strength was measured based on JIS K7110.

[Recyclability]
Using a single screw extruder with a screw diameter of 40φ, granulation was repeated three times at a cylinder temperature of 250 ° C. to produce pellets. Then, using this pellet, the drawdown resistance, the uneven thickness of the molded product, the surface appearance and the impact resistance were measured and evaluated in the same manner as described above, and the recyclability was evaluated according to the following criteria.

○: Drawdown resistance is 60 seconds or more, thickness deviation is ○, surface appearance is ○, Izod impact strength is 5.5 kgf · cm / cm2 or more,
X: At least one of drawdown resistance, uneven thickness of the molded article, surface appearance and impact resistance does not satisfy the above.

[Example 1]
BX930 (weight average molecular weight Mw: 330,000), which is made by Nippon Polystyrene Co., Ltd., GPPS (General Purpose Polystyrene; general-purpose polystyrene), and HIPS (High Impact Polystyrene; high-impact polystyrene), made by Nippon Polystyrene Co., Ltd. H758K (weight average molecular weight Mw: 250,000, gel amount: 21 wt%) blended at a ratio of 45/55 (weight ratio) is granulated at 220 ° C by a twin screw extruder with a screw diameter of 35 mm And uniform pellets were produced. Then, using the pellets, the above measurement / evaluation was performed. The results are shown in Table 1.

[Example 2]
H758K (weight average molecular weight Mw: 250,000, gel amount: 21% by weight) manufactured by Nippon Polystyrene Co., Ltd. and GPPS (weight average molecular weight Mw: 2 million) manufactured by GE Specialty Chemicals are 98.5. The blended product was granulated at 220 ° C. with a twin screw extruder having a screw diameter of 35 mm at a ratio of /1.5 (weight ratio) to produce uniform pellets. Then, using the pellets, the above measurement / evaluation was performed. The results are shown in Table 1.

Example 3
A rubber-modified styrenic resin composition was produced in a continuous polymerization apparatus as follows. The apparatus was composed of a complete mixing tank having an internal volume of 17 L, a 30-liter two-stage tower reactor, a devolatilization tank, an extruder and a granulator in series.

  91 parts by weight of styrene as a raw material solution, 3 parts by weight of ethylbenzene, 6 parts by weight of a rubbery polymer (manufactured by Asahi Kasei Co., Ltd., Diene 55), 2,2-bis (4,4-di-tert-butylperoxycyclohexyl) as an initiator ) 0.01 parts by weight of propane and 0.005 parts by weight of divinylbenzene as a branching agent were supplied to the complete mixing tank at 14 l / hr to conduct a polymerization reaction. The rotation speed of the stirring blade of the complete mixing tank was 50 rpm, and the reaction temperature was 125 ° C. Next, the obtained solution was supplied to a two-stage column reactor, and tert-dodecyl mercaptan was added as a chain transfer agent so as to correspond to 0.02 part by weight with respect to the raw material solution. Polymerization was performed at outlet temperatures of 130 ° C. and 155 ° C., respectively. The polymerization solution discharged from the second tower reactor was supplied to a devolatilization tank where the polymer was separated from unreacted styrene and ethylbenzene. And the pellet was obtained through the extruder and the granulator.

  Then, using the pellets, the above measurement / evaluation was performed. The results are shown in Table 1.

Example 4
A rubber-modified styrenic resin composition was produced in a continuous polymerization apparatus as follows. The apparatus was the same as that used in Example 3, and a complete mixing tank having an internal volume of 17 L, a two-stage tower-type reaction tank, a devolatilization tank, an extruder, and a granulator were configured in series.

  93 parts by weight of styrene as a raw material solution, 3 parts by weight of ethylbenzene, 4 parts by weight of a rubber-like polymer (D-55, manufactured by Asahi Kasei Corporation), 2,2-bis (4,4-di-tert-butylperoxy as an initiator Cyclohexyl) propane (0.02 part by weight) was supplied to the complete mixing tank at 14 l / hr to carry out the polymerization reaction. The rotation speed of the stirring blade of the complete mixing tank was 100 rpm, and the reaction temperature was 115 ° C. Next, the obtained solution was supplied to a two-stage column reactor, and tert-dodecyl mercaptan was added as a chain transfer agent so as to correspond to 0.01 part by weight with respect to the raw material solution. Polymerization was performed at outlet temperatures of 120 ° C. and 165 ° C., respectively. The polymerization solution discharged from the second tower reactor was supplied to a devolatilization tank where the polymer was separated from unreacted styrene and ethylbenzene. And the pellet was obtained through the extruder and the granulator.

  Then, using the pellets, the above measurement / evaluation was performed. The results are shown in Table 1.

[Comparative Example 1]
G899 (weight average molecular weight Mw: 350,000) manufactured by Nippon Polystyrene Co., Ltd. and H758K (weight average molecular weight Mw: 250,000, gel amount: 21% by weight) manufactured by Nippon Polystyrene Co., Ltd. and HIPS Were blended at a ratio of 50/50 (weight ratio) at 220 ° C. with a twin screw extruder having a screw diameter of φ35 mm to produce uniform pellets. Then, using the pellets, the above measurement / evaluation was performed. The results are shown in Table 2.

[Comparative Example 2]
BX930 (weight average molecular weight Mw: 330,000) manufactured by Nippon Polystyrene Co., Ltd. and H758K (weight average molecular weight Mw: 250,000, gel amount: 21% by weight) manufactured by Nippon Polystyrene Co., Ltd. and HIPS Was blended at a ratio of 70/30 (weight ratio) at 220 ° C. with a twin screw extruder having a screw diameter of 35 mm to produce uniform pellets. Then, using the pellets, the above measurement / evaluation was performed. The results are shown in Table 2.

[Comparative Example 3]
H758K (weight average molecular weight Mw: 250,000, gel amount: 21% by weight) manufactured by Nippon Polystyrene Co., Ltd. and GPPS (weight average molecular weight Mw: 2 million) manufactured by GE Specialty Chemicals are 99/1. The blended material at a ratio of (weight ratio) was granulated at 220 ° C. by a twin screw extruder having a screw diameter of 35 mm to produce uniform pellets. Then, using the pellets, the above measurement / evaluation was performed. The results are shown in Table 2.

[Comparative Example 4]
BX930 (weight average molecular weight Mw: 330,000) manufactured by Nippon Polystyrene Co., Ltd. and H758K (weight average molecular weight Mw: 250,000, gel amount: 21% by weight) manufactured by Nippon Polystyrene Co., Ltd. and HIPS , Liquid paraffin (Esso Standard, Christol J-352) blended at a ratio of 45/55/2 (weight ratio) and granulated at 220 ° C. using a twin screw extruder with a screw diameter of 35 mm And uniform pellets were produced. Then, using the pellets, the above measurement / evaluation was performed. The results are shown in Table 2.

[Comparative Example 5]
The raw material solution supplied to the complete mixing tank was 89 parts by weight of styrene, 3 parts by weight of ethylbenzene, 6 parts by weight of a rubbery polymer (Asahi Kasei Corporation, D-55), liquid paraffin (Esso Standard, Christol J-352). ) Pellets were produced in the same manner as in Example 3 except that the amount was 2 parts by weight. Then, using the pellets, the above measurement / evaluation was performed. The results are shown in Table 3.

[Comparative Example 6]
A rubber-modified styrenic resin composition was produced in a continuous polymerization apparatus as follows. The apparatus was the same as that used in Example 3, and a complete mixing tank having an internal volume of 17 L, a two-stage tower-type reaction tank, a devolatilization tank, an extruder, and a granulator were configured in series.

  93 parts by weight of styrene as a raw material solution, 3 parts by weight of ethylbenzene, 4 parts by weight of a rubber-like polymer (D-55, manufactured by Asahi Kasei Corporation), 2,2-bis (4,4-di-tert-butylperoxy as an initiator Cyclohexyl) propane (0.015 parts by weight) and divinylbenzene (0.005 parts by weight) as a branching agent were supplied to the complete mixing tank at 14 l / hr to conduct a polymerization reaction. The rotation speed of the stirring blade of the complete mixing tank was 70 rpm, and the reaction temperature was 118 ° C. Next, the obtained solution was supplied to a two-stage column reactor, and tert-dodecyl mercaptan was added as a chain transfer agent so as to correspond to 0.01 part by weight with respect to the raw material solution. Polymerization was performed at outlet temperatures of 120 ° C. and 165 ° C., respectively. The polymerization solution discharged from the second tower reactor was supplied to a devolatilization tank where the polymer was separated from unreacted styrene and ethylbenzene. And the pellet was obtained through the extruder and the granulator.

  Then, using the pellets, the above measurement / evaluation was performed. The results are shown in Table 3.

[Comparative Example 7]
The above measurement / evaluation was performed using H640N (weight average molecular weight: Mw 240,000, gel amount: 18% by weight), which is made by Nippon Polystyrene Co., Ltd. and HIPS. The results are shown in Table 3.

  As is clear from Tables 1, 2 and 3, the rubber-modified styrenic resin compositions of Examples 1 to 4 of the present invention are excellent in draw-down resistance, and the uneven thickness and surface appearance of the obtained molded products. It was also excellent.

  On the other hand, the rubber-modified styrene resin of Comparative Example 1 in which the weight-average molecular weight (Mw) of the polystyrene-based resin is 300,000 or more and the ratio of the Z-average molecular weight to the weight-average molecular weight (Mz / Mw) is less than 1.9. The composition was inferior to the uneven thickness property and surface appearance of the molded product obtained as compared with the rubber-modified styrene resin compositions of the present invention of Examples 1 to 4.

  The rubber-modified styrenic resin composition of Comparative Example 2 in which the weight-average molecular weight (Mw) of the polystyrene-based resin is 300,000 or more and the gel amount in the resin composition is less than 10% by weight is that of Examples 1-4. Compared with the rubber-modified styrene resin composition of the present invention, the surface appearance of the obtained molded product was inferior.

  The rubber-modified styrene-based resin composition of Comparative Example 3 in which the Z-average molecular weight (Mz) of the polystyrene-based resin is less than 500,000 is compared with the rubber-modified styrene-based resin composition of the present invention of Examples 1 to 4, It was inferior to the drawdown resistance, and the uneven thickness of the obtained molded product was also inferior.

  The rubber-modified styrenic resin composition of Comparative Example 4 in which the methanol-soluble content in the resin composition exceeds 1.5% by weight is compared with the rubber-modified styrene-based resin composition of the present invention of Examples 1 to 4. In addition, it was inferior in draw-down resistance and inferior in thickness unevenness of the obtained molded product.

  The rubber-modified styrenic resin composition of Comparative Example 5 in which the methanol-soluble content in the resin composition exceeds 1.5% by weight is compared with the rubber-modified styrene-based resin composition of the present invention of Examples 1 to 4. In addition, it was inferior in draw-down resistance and inferior in thickness unevenness of the obtained molded product.

The rubber-modified styrene-based resin composition of Comparative Example 6 in which the weight-average molecular weight (Mw) of the polystyrene-based resin exceeds 300,000 and the ratio of the weight-average molecular weight to the number-average molecular weight (Mw / Mn) is 3 or more was carried out. Compared with the rubber-modified styrenic resin compositions of Examples 1 to 4 of the present invention, the surface appearance of the obtained molded products was inferior.
The polystyrene-based resin has a weight average molecular weight (Mw) of less than 250,000, a Z average molecular weight (Mz) of less than 500,000, and a ratio of the weight average molecular weight to the number average molecular weight (Mw / Mn) of less than 2.5. The rubber-modified styrene of Comparative Example 7 in which the ratio of the Z-average molecular weight to the weight-average molecular weight (Mz / Mw) is less than 1.9, and the methanol-soluble content in the resin composition exceeds 1.5% by weight Compared with the rubber-modified styrene resin composition of the present invention of Examples 1 to 4, the resin-based resin composition was inferior in draw-down resistance and inferior in thickness unevenness of the obtained molded product.

Example 5
For a total of 100 parts by weight of BX930 and H758K, manufactured by Sumitomo Chemical Co., Ltd., a phosphorus processing stabilizer, 0.3 parts by weight of Sumizer GP, manufactured by Sumitomo Chemical Co., Ltd., a phenolic stabilizer A pellet was prepared in the same manner as in Example 1 except that 0.3 parts by weight of the Sumilizer GM was added. That is, BX930 (weight average molecular weight Mw: 330,000) manufactured by Nippon Polystyrene Co., Ltd. and H758K (weight average molecular weight Mw: 250,000 manufactured by Nippon Polystyrene Co., Ltd., gel amount: 21% by weight) ) Is blended at a ratio of 45/55 (weight ratio), and a total of 100 parts by weight of BX930 and H758K is a phosphoric processing stabilizer, Sumitomo Chemical Co., Ltd. Add 0.3 parts by weight of GP, Sumitomo Chemical Co., Ltd., which is a phenolic stabilizer, 0.3 parts by weight of Sumilizer GM, and granulate at 220 ° C. using a twin screw extruder with a screw diameter of 35 mm. A uniform pellet was produced. And the recyclability was evaluated using this pellet. The results are shown in Table 4.

Example 6
The stabilizer to be added is Sumitomo Chemical Co., Ltd., which is a phosphorus processing stabilizer, and 0.3 parts by weight of Sumilizer GP with respect to a total of 100 parts by weight of BX930 and H758K, Sumitomo Chemical, which is a phenolic stabilizer. A pellet was produced in the same manner as in Example 4 except that the Sumitizer GS manufactured by Kogyo Co., Ltd. was 0.3 parts by weight with respect to 100 parts by weight in total of BX930 and H758K. And the recyclability was evaluated using this pellet. The results are shown in Table 4.

  Abbreviations in the table are as follows.

Phosphorus processing stabilizer: Sumitomo Chemical Co., Ltd.
(6- [3- (3-tert-Butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4,8,10-tetra-tert-butyldibenzo [d, f] [1.3.2 ] Dioxaphosphepine)
Phenol-based processing stabilizer (b-1): Sumitomo Chemical Co., Ltd., Smither GM
(2-tert-butyl-6- (3-tert-butyl-5-methyl-2-hydroxybenzyl) -4-methylphenyl acrylate),
Phenol-based processing stabilizer (b-2): Sumitomo Chemical Co., Ltd., Smither GS
(2,4-Di-tert-amyl-6- (3,5-di-tert-amyl-2-hydroxy-α-methylbenzyl) phenyl acrylate).

  In Table 4, the drawdown resistance, the uneven thickness of the molded product, the surface appearance, and the impact resistance were measured and evaluated in the evaluation of recyclability.

Example 7
The stabilizer to be added is Sumitomo Chemical Co., Ltd., which is a phosphorus processing stabilizer, and 0.05 parts by weight of Sumilizer GP with respect to a total of 100 parts by weight of BX930 and H758K, Sumitomo Chemical, which is a phenolic stabilizer. A pellet was produced in the same manner as in Example 4 except that the Sumitizer GM manufactured by Kogyo Co., Ltd. was 0.05 parts by weight with respect to 100 parts by weight of the total of BX930 and H758K. And the recyclability was evaluated using this pellet. The results are shown in Table 5.

Example 8
The stabilizer to be added is Sumitomo Chemical Co., Ltd., which is a phosphorus processing stabilizer, and 0.3 parts by weight of Sumilizer GP with respect to a total of 100 parts by weight of BX930 and H758K, Sumitomo Chemical, which is a phenolic stabilizer. A pellet was prepared in the same manner as in Example 4 except that the Sumitizer GM manufactured by Kogyo Co., Ltd. was 0.1 parts by weight with respect to 100 parts by weight in total of BX930 and H758K. And the recyclability was evaluated using this pellet. The results are shown in Table 5.

Example 9
The stabilizer to be added is Sumitomo Chemical Co., Ltd., which is a phosphorus processing stabilizer, and 0.1 part by weight of Sumilizer GP with respect to a total of 100 parts by weight of BX930 and H758K. Sumitomo Chemical is a phenolic stabilizer. A pellet was produced in the same manner as in Example 4 except that the Sumitizer GM manufactured by Kogyo Co., Ltd. was 0.3 parts by weight with respect to 100 parts by weight in total of BX930 and H758K. And the recyclability was evaluated using this pellet. The results are shown in Table 5.

  The abbreviations in Table 5 are the same as the abbreviations in Table 4.

  Further, the drawdown resistance, thickness deviation of the molded product, surface appearance and impact resistance in Table 5 were measured and evaluated in the evaluation of recyclability.

Example 10
The stabilizer to be added is Sumitomo Chemical Co., Ltd., which is a phosphorus processing stabilizer, and Sumizer GP is 1.0 part by weight with respect to 100 parts by weight of BX930 and H758K in total, and a phenolic stabilizer is added. Pellets were produced in the same manner as in Example 4 except that there was no. And the recyclability was evaluated using this pellet. The results are shown in Table 6.

Example 11
The stabilizer to be added is Sumitomo Chemical Co., Ltd., which is a phenol-based stabilizer, and the Sumilizer GM is 1.0 part by weight with respect to a total of 100 parts by weight of BX930 and H758K, and a phosphorus-based processing stabilizer is added. Pellets were produced in the same manner as in Example 4 except that there was no. And the recyclability was evaluated using this pellet. The results are shown in Table 6.

Example 12
The stabilizer to be added is Sumitomo Chemical Co., Ltd., which is a phenol-based stabilizer, and 1.0 part by weight with respect to a total of 100 parts by weight of BX930 and H758K, and a phosphorus-based processing stabilizer is added. Pellets were produced in the same manner as in Example 4 except that there was no. And the recyclability was evaluated using this pellet. The results are shown in Table 6.

  The abbreviations in Table 6 are the same as the abbreviations in Table 4.

  Further, the drawdown resistance, uneven thickness of the molded product, surface appearance and impact resistance in Table 6 are measured and evaluated in the evaluation of recyclability.

  As is apparent from Tables 4, 5 and 6, the rubber-modified styrene resin compositions of Examples 4 and 5 of the present invention are excellent in recyclability, and are suitable for recycling burrs of molded products produced during molding. It was.

  On the other hand, the rubber-modified styrenic resin composition of Example 7 in which the total content of the phosphorus-based processing stabilizer and the phenol-based processing stabilizer is less than 0.2 parts by weight with respect to 100 parts by weight of the total of BX930 and H758K. Compared to the rubber-modified styrenic resin compositions of the present invention in Examples 5 and 6, the draw-down resistance during recycling is inferior, and the unevenness and impact resistance of the molded product obtained during recycling are also inferior. As a result, the burr recyclability of the molded product generated during molding was inferior.

  The rubber-modified styrene resin composition of Example 8 in which the content ratio (mass basis) of the phenol-based processing stabilizer to the phosphorus-based processing stabilizer is less than 0.5 is the rubber-modified styrene of the present invention of Examples 5 and 6. Compared with the resin-based resin composition, the drawdown resistance at the time of recycling was inferior, the impact resistance of the molded product obtained at the time of recycling was also inferior, and the burr recyclability of the molded product generated at the time of molding was inferior.

  The rubber-modified styrenic resin composition of Example 9 in which the content ratio (mass basis) of the phenol-based processing stabilizer to the phosphorus-based processing stabilizer exceeds 2 is the rubber-modified styrenic resin composition of the present invention of Examples 5 and 6. Compared to products, the drawdown resistance at the time of recycling is inferior, the unevenness and impact resistance of the molded product obtained at the time of recycling are also inferior, and the burr recycling property of the molded product generated at the time of molding is inferior. .

  The rubber-modified styrenic resin composition of Example 10 in which no phenol-based stabilizer was added was compared with the rubber-modified styrenic resin compositions of Examples 5 and 6 of the present invention in the molded product obtained during recycling. It was inferior in impact resistance, and the recyclability of the burr of the molded product produced at the time of molding was inferior.

  The rubber-modified styrenic resin composition of Example 11 in which no phosphorus processing stabilizer was added was compared with the rubber-modified styrenic resin compositions of Examples 5 and 6 of the present invention and resistance to drawdown during recycling. The molded product obtained at the time of recycling was inferior in thickness and impact resistance, and the burr of the molded product produced during molding was inferior in recyclability.

  The rubber-modified styrenic resin composition of Example 12 to which no phosphorus processing stabilizer was added was compared with the rubber-modified styrene resin compositions of Examples 5 and 6 of the present invention, and the drawdown resistance during recycling was reduced. The molded product obtained at the time of recycling was inferior in thickness and impact resistance, and the burr of the molded product produced during molding was inferior in recyclability.

  The rubber-modified styrenic resin composition of the present invention can discharge parison stably, particularly in large blow molding, and has good drawdown resistance. A molded product obtained from the rubber-modified polystyrene resin composition has little uneven thickness and an excellent appearance. Therefore, the rubber-modified styrenic resin composition of the present invention is suitable for materials in a wide range of fields such as bathroom ceilings and walls, and household equipment such as bathroom vanities.

  In addition, the rubber-modified styrene resin composition of the present invention is excellent in recyclability of the burr of a molded product produced during molding, and is an economically excellent material.

  Accordingly, the rubber-modified styrenic resin composition of the present invention plays a significant role in the industry.

Claims (7)

A rubber-modified styrenic resin composition containing a rubbery polymer as dispersed particles in a polystyrene-based resin as a matrix,
The polystyrene resin has a weight average molecular weight (Mw) of 250,000 to 300,000, a Z average molecular weight (Mz) of 500,000 or more, and a ratio (Mw / Mn) between the weight average molecular weight and the number average molecular weight. 2.5 or more and less than 3, the ratio (Mz / Mw) of the Z average molecular weight to the weight average molecular weight is 1.9 or more,
The average particle size of the dispersed particles is 0.5 μm to 5 μm,
The amount of gel in the resin composition is 10 wt% to 24 wt%,
A rubber-modified styrenic resin composition, wherein a methanol-soluble component in the resin composition is 1.5% by weight or less. The rubber-modified styrenic resin composition according to claim 1, a phosphorus processing stabilizer, and a phenol processing stabilizer,
The total content of the phosphorus-based processing stabilizer and the phenol-based processing stabilizer is 0.2 to 1 part by weight with respect to 100 parts by weight of the rubber-modified styrenic resin composition according to claim 1,
A rubber-modified styrenic resin composition in which the content ratio (mass basis) of the phenol-based processing stabilizer to the phosphorus-based processing stabilizer is 0.5 to 2 (phenol-based processing stabilizer / phosphorus-based processing stabilizer).   The phenolic processing stabilizer is 2-tert-butyl-6- (3-tert-butyl-5-methyl-2-hydroxybenzyl) -4-methylphenyl acrylate or 2,4-di-tert-amyl-6. The rubber-modified styrenic resin composition according to claim 2, which is at least one of-(3,5-di-tert-amyl-2-hydroxy-α-methylbenzyl) phenyl acrylate.   The phosphorus-based processing stabilizer is 6- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4,8,10-tetra-tert-butyldibenzo [d, f [1.3.2] The rubber-modified styrenic resin composition according to claim 2, which is at least one of dioxaphosphine and tris (2,4-di-tert-butylphenyl) phosphite. .   The rubber-modified polystyrene resin composition according to any one of claims 1 to 4, which is used for blow molding.   A molded product obtained by blow molding the rubber-modified polystyrene resin composition according to claim 5.   A molded article obtained by blow molding a rubber-modified polystyrene resin composition containing burrs generated in a molded article obtained by blow molding the rubber-modified polystyrene resin composition according to claim 2.