JP2001064464A - Thermoplastic resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition capable of improving processability in vacuum forming and pressure forming by compounding a styrene-based resin with a specific processing aid for the styrene-based resin in a specified amount. SOLUTION: This composition is obtained by compounding (A) 100 pts.wt. of a styrene-based resin (e.g. an ABS resin) with (B) 0.3-10 pts.wt. of a processing aid for the styrene-based resin comprising a styrene-based polymer in which >=60 wt.% is composed of a styrene-based monomer unit and the weight-average molecular weight is >=6,700,000. The component A preferably comprises (i) a continuous phase of a styrene-based copolymer prepared by polymerizing a mixture of (i) a styrene-based monomer (e.g. styrene) with a vinyl cyanide-based monomer (e.g. acrylonitrile), etc., and (ii) a dispersed phase of a graft copolymer in which the graft polymerization of a graft branch of the component (i) with a rubber-like polymer is carried out. The molecular weight of the component (i) is preferably 50,000 to 300,000 and the ratio of the components (i) to (ii) is preferably (50-85):(50-15) wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin composition using a processing aid for an ultrahigh molecular weight styrene resin.
More specifically, the present invention relates to a thermoplastic resin composition that can improve the thermal processability, particularly the processability in vacuum forming and pressure forming of a sheet produced by an extrusion molding method.

[0002]

2. Description of the Related Art Styrene resins, especially polystyrene resins, AS resins and ABS resins, are excellent in moldability and rigidity and are therefore used in large quantities as molding materials for household goods, electric appliances and the like.

[0003] In general, when a sheet produced by an extrusion molding method is used to form a desired shape by a molding method such as vacuum molding or air pressure molding, a molding material is suitable for the molding method over a wide temperature range. Characteristics that maintain high viscosity are required.

[0004] For example, in the case of performing thermoforming using an ABS resin, it is necessary to appropriately increase the material viscosity with an increase in the stretching ratio during the forming.
In this case, it is conceivable to increase the melt viscosity by increasing the average molecular weight of the ABS resin itself. However, the viscosity at the time of stretching increases and the processing temperature must be increased, and as a result, the time for molding and processing is prolonged. Is done. In addition, in order to improve the viscosity characteristics at the time of stretching, a method of including both components of an AS resin having a large average molecular weight and an AS resin having a small average molecular weight in an ABS resin, or adjusting the molecular weight distribution of the AS resin is also proposed. However, the molding temperature is high and the processing time is long, so that it cannot be said that thermoforming in a short time by vacuum forming, pressure forming or the like is sufficient.

[0005] Further, when the stretching ratio is large, it is desired that unfavorable uneven wall thickness does not occur in the molded product, and that the processing temperature is low and the processing time is short.

In these molding methods, a molding apparatus to be used,
It is desired to easily obtain a desired melt viscosity according to the molding conditions and the shape of the molded product. Therefore, there is great expectation for a processing aid capable of arbitrarily adjusting the melt viscosity of the styrene resin.

For example, when a molded article such as an inner box of an electric refrigerator or a door liner is manufactured by blowing, vacuum, or pressure forming using an extruded sheet of ABS resin, the stretching ratio becomes 4 to 6 times. High formability is required. There should be little deformation when heating the sheet. Normally, processing of the inner box molded product is heating the sheet → blowing by air injection → forced stretching with a plug → vacuum suction ・
It consists of the steps of mold transfer by compressed air → cooling → mold release of the molded product. In this case, if the heating (radiant heat) of the sheet and the deformation due to its own weight increase, in extreme cases, contact with the device occurs, or the distance between the deformed portion and the heater decreases,
The temperature distribution of the sheet due to the radiant heat from the heater becomes extremely large. If the temperature distribution becomes extreme in the heating step of the sheet, the high-temperature portion of the sheet is stretched in the next blowing step, and the portion becomes extremely thin or ruptures in some cases. Further, in the next plug stretching step, the irregularities on the plug surface are transferred to the molded product. This is because the heated portion of the blown sheet has a low material viscosity, so that the heated sheet does not slip on the surface of the contacted plug and remains in contact until the next step, so that the unevenness of the plug surface In some cases, the final step may be completed in a state of poor appearance with strong transfer. In addition, if there is a temperature distribution in the portion that is stretched in the plug stretching process, the portion where the temperature is high and the viscosity is low is greatly stretched, and a thick portion and a thin portion are generated. The phenomenon occurs. At the same time, when a portion having a low temperature and a high viscosity is forcibly stretched at a higher speed by the plug, the orientation in the stretching direction remains stronger than other portions. In this case, when heat is subsequently applied, the orientation is relaxed, a thermal expansion / contraction phenomenon occurs, and the shape itself changes.
In addition, the part with low viscosity and high viscosity cannot reproduce the unevenness of the mold even in the mold transfer process using vacuum and compressed air, and if the radius of curvature of the corners and ribs of the mold is small, follow Molding cannot be performed, and the radius of curvature of the portion of the molded product becomes large.

A wide molding temperature range. In particular, it is desired that good products can be obtained in a wide temperature range in which molding can be performed at a lower molding temperature. Since the glass transition temperature of the AS resin, which is a continuous phase of the ABS resin, is about 100 ° C.,
The sheet temperature during molding is set so as to keep the temperature higher than this. It is desired that the molding can be performed while maintaining the molding temperature at a high temperature. However, as described above, the molding stability is reduced due to the high temperature. Desirably, the moldability is good on the low temperature side. This is because heat energy can be reduced and molding stability can be easily obtained. Further, the sheet is heated to a glass transition point temperature of 100 ° C. or higher,
After the stretching process, the molded article is cooled to 100 ° C. or less. If the stretching process can be performed at a low temperature without any problem, the heating and cooling time is short, and the entire period from the heating of the sheet to the cooling of the molded article is reduced. The process time is short, and productivity per unit time is improved.

[0009] The plug and the mold have slipperiness. If there is no slippage between the heated and blown sheet and the plug, only the portion not in contact with the plug is stretched in the plug stretching step. If the contact surface between the plug and the heated, blown sheet is large, the area not in contact with the plug will be small, and in this case, if there is no slip, only the small part not in contact with the plug will be stretched, The thickness of this part is also reduced. Uneven thickness will be seen as a final product. Furthermore, in the mold transfer step by vacuum / pressurized air, which is the next step of plug stretching, if there is no slippage between the heating sheet and the mold, only the portion not in contact with the mold will be stretched. In the concave and convex portions of the mold, when the film is further stretched to follow the shape, if there is no slipperiness, a thin portion is observed on the inner surface of the concave portion. The thin portion has low strength and is easily deformed and cracked by external force.

Good transfer to a mold. The heated sheet is not heated in the subsequent processing steps, but radiates heat in each step up to the cooling step, and the temperature of the sheet decreases. Further, the stretching ratio also increases with each step. Among these, the step of transferring to the mold is the final stretching step, and it is required that the stretching and deformation can be sufficiently performed by vacuum and pressure and the transfer to the mold is good. If the mold transfer is insufficient, the radius of curvature of the corners and ribs of the mold will not be reproduced, and it will not be possible to insert or fit components in a later process.

As described above, even when a molded product is obtained by blowing, vacuum, or air-pressure molding using an extruded sheet of ABS resin, characteristics related to molding, such as a molding device, a plug, a mold shape, a material, and a sheet material, are not obtained. Because of the wide variety, it is difficult to determine the molding conditions from the values such as the melt flow rate of the sheet material.
It could not be determined whether or not the moldability was excellent.

In recent years, conventional styrenic resins have been increasingly used due to the increase in the size of thermoformed products, the complexity of their shapes, and the reduction in sheet thickness and molding cycle time for cost reduction. It is difficult to satisfy the above moldability.

[0013]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and uses a sheet produced by a styrene-based resin extrusion molding method to perform thermoforming, especially vacuum forming, pressure forming, etc. In the molding method of the present invention, when molding into a desired shape, the molding cycle can be shortened, the appropriate molding temperature range is wide, and when molding into the desired shape, it is possible to provide a thermoplastic resin composition having good moldability. is there.

[0014]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have blended an ultrahigh molecular weight styrene polymer having a specific molecular weight into a styrene resin as a processing aid. As a result, the present inventors have found that a thermoplastic resin composition having improved thermoformability of a sheet produced by a styrene-based resin extrusion molding method has been obtained, and the present invention has been accomplished.

That is, the present invention provides a styrene resin (A)
Styrene-based resin processing aid (B) 0.3 composed of a styrene-based polymer having a styrene-based monomer content of 60% by weight or more and a weight-average molecular weight of 6.7 million or more based on 100 parts by weight. It is a thermoplastic resin composition containing 10 to 10 parts by weight.

Further, the present invention provides a styrene resin (A)
Is a styrene-based copolymer obtained by polymerizing a monomer mixture of a styrene-based monomer, a vinyl cyanide-based monomer, and optionally a vinyl-based monomer copolymerizable with these monomers. (A) a continuous phase, a monomer mixture of a styrene monomer, a vinyl cyanide monomer, and optionally a vinyl monomer copolymerizable with these monomers in a rubbery polymer And a continuous phase of the styrene-based copolymer (a) having a weight average molecular weight of 5
It is a thermoplastic resin composition of 10,000 to 300,000. Preferably, the ratio of the continuous phase styrene copolymer (a) and the dispersed phase graph copolymer (b) constituting the styrene resin (A) is 50 to 85:50 by weight. It is more preferably within a range of 15% by weight, and more preferably, a graft copolymer of a continuous phase styrene copolymer (a) and a dispersed phase (b) satisfying the above requirements and constituting the styrene resin (A). )), The proportion of the styrene-based monomer, vinyl cyanide-based monomer, and optionally the monomer copolymerizable therewith is 60 to 80:15 to 45: 0 to 20 by weight.
(However, the total of the monomers is 100% by weight).

Hereinafter, the present invention will be described in detail. As the styrene resin (A) of the present invention, a styrene monomer, a vinyl cyanide monomer, and a monomer mixture of a vinyl monomer copolymerizable with these monomers as the case may be. The continuous phase of the styrene-based copolymer (a) obtained by polymerization and the rubbery polymer are added to a vinyl cyanide-based monomer, a styrene-based monomer, and optionally a vinyl copolymerizable with these monomers. A polymer composed of a graft phase of a graft copolymer (b) obtained by graft-polymerizing a graft branch of a copolymer composed of a monomer mixture of system monomers is preferable.

The styrenic monomers constituting the styrenic copolymer (a) and the graft copolymer (b) contained in the styrenic resin (A) according to the present invention include styrene and α-methylstyrene. Dimethylstyrene, vinyltoluene, etc., of which styrene is preferred. Examples of the vinyl cyanide monomer include acrylonitrile, methacrylonitrile, fumaronitrile, and the like. Among these, acrylonitrile is preferable. Optionally, these copolymerizable monomers include:
Methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, methacrylic acid-2-
Styrene methacrylate monomers such as ethylhexyl, phenyl methacrylate, benzyl methacrylate, isobornyl methacrylate, etc., methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate Such as acrylic acid ester monomers, maleic acid, itaconic acid, unsaturated dicarboxylic anhydride monomers such as citraconic anhydride, maleimide, N-methylmaleimide, N-butylmaleimide, N-phenylmaleimide,
Examples thereof include imide compound monomers of unsaturated dicarboxylic acids such as N-cyclohexylmaleimide, and these vinyl monomers can be used alone or in combination of two or more.

The rubbery polymer constituting the graft copolymer (b) used in the present invention includes butadiene-based polymers such as polybutadiene, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer, polyisoprene, and polychloroprene. Examples thereof include acrylate polymers such as coalescable polymers, propyl acrylate polymers, and butyl acrylate polymers, and ethylene-propylene-conjugated diene rubbers. These rubbery polymers may be used alone or
A mixture of more than one species can be used.

The method for producing the graft copolymer (b) includes known polymerization methods such as an emulsion polymerization method, a suspension polymerization method, a bulk polymerization method, and an emulsion-suspension polymerization method in a batch system and / or a continuous system. Used in combination. Among these, the method for producing the graft copolymer (b) is preferably an emulsion polymerization method. In the case where a latex-like rubbery polymer is used, a styrene monomer and a vinyl cyanide monomer are used. It is preferable to polymerize a monomer mixture of a monomer copolymerizable therewith by an emulsion polymerization method. However, in these production methods, it is difficult to obtain only the graft copolymer (b) obtained by graft-grafting the above-mentioned rubber-like polymer with the graft branch alone, and the styrene-based copolymer (a) not grafted to the rubber-like polymer is used. It is generally a mixture with Therefore, in the present invention, the polymer obtained by the above production method is referred to as a graft polymer (C), and when the graft copolymer (b) is obtained alone, the graft copolymer (b) and the graft polymer are used. (C) is the same, and the others are mixtures with the styrenic copolymer (a).

The composition ratio of the rubbery polymer and the monomer mixture in the above production method is selected in the range of 40 to 70% by weight of the monomer mixture in the presence of 30 to 60% by weight of the rubbery polymer. Is preferred. At this time, it is preferable that the particle diameter of the graft copolymer is usually selected in the range of 0.2 to 0.8 μm. In the case of the emulsion polymerization method, the reaction is carried out in a temperature range of 50 to 90 ° C using an emulsifier, a polymerization initiator and a chain transfer agent. A known emulsifier can be used, and is not particularly limited. For example, anionic surfactants such as fatty acid salts, alkyl sulfate salts, alkyl benzene sulfonate salts, alkyl acid ester salts, alkyl diphenyl ether sulfonate salts, and polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters And nonionic surfactants such as glycerin fatty acid esters, and cationic surfactants such as alkylamine salts. These emulsifiers can be used alone or in combination.

The polymerization initiator may be a water-soluble or oil-soluble single type or a redox type.
An ordinary inorganic initiator such as a persulfate can be used alone, or can be used as a redox initiator in combination with a sulfite, a hydrogen sulfite, a thiosulfate, or the like. Further, t-butyl hydroperoxide, cumene hydroperoxide, benzoyl peroxide, organic peroxides such as lauroyl peroxide, azo compounds or the like may be used alone or in combination with sodium formaldehyde sulfoxylate and the like, or a redox initiator. Can also be used. The amount of these polymerization initiators is usually selected in the range of 0.1 to 5% by weight based on the monomer mixture.

Examples of the chain transfer agent include mercaptans such as n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, terpinolene, and α-methylstyrene dimer.

The styrene copolymer (a) contained in the styrene resin (A) of the present invention has a weight average molecular weight of 50,000 to 50,000.
Preferably, it is 300,000.

The content ratio of each component constituting the styrenic resin (A) of the present invention is such that the weight ratio of the styrenic copolymer (a) to the graft copolymer (b) is 50 to 85:
Preferably it is in the range of 50 to 15% by weight. When the ratio of the styrenic copolymer (a) component to the graft copolymer (b) component is out of the above range, the impact resistance of the thermoplastic resin composition containing the styrenic resin processing aid (B) is reduced. The physical properties such as properties and tensile strength are inferior and the moldability is inferior. If the proportion of the styrene-based copolymer (a) in the thermoplastic resin composition is too large, the melt viscosity during thermoforming tends to be small, and the sheet tends to be deformed due to its own weight during heating. On the other hand, if the amount is too small, the melt viscosity becomes large, and it is necessary to raise the processing temperature or extend the molding cycle, and the mold transfer tends to be insufficient.

The styrenic copolymer (a) of the present invention
The ratio of the styrene monomer, the vinyl cyanide monomer, and the monomer copolymerizable therewith in the graft copolymer (b) is 60 to 80: 1 by weight.
5 to 45: 0 to 20 (where the total number of monomers is 1
00% by weight. ) Is preferable.

The styrenic copolymer (a) of the present invention may be by-produced when producing the graft copolymer (b) or may be produced separately. When it is manufactured separately, it is obtained according to a known manufacturing method. Specifically, a styrene-based monomer, a vinyl cyanide-based monomer, and optionally another monomer copolymerizable therewith, are added in the presence of a polymerization initiator and, if necessary, a chain transfer agent. , An emulsion polymerization method, a suspension polymerization method or a bulk polymerization method. As the polymerization initiator and the chain transfer agent used at this time, the same types as those used when producing the above graft copolymer (b) can be mentioned.

Representative examples of the styrene resin (A) include ABS resin, MBS resin and AES resin.

Further, the styrenic resin (A) in the present invention is generally used for molding, and includes polystyrene (GPPS), high impact polystyrene (HIPS) containing a rubbery polymer, and These include, for example, polystyrene resins containing other monomers such as acrylonitrile, maleic anhydride, methyl methacrylate, butyl acrylate, N-phenylmaleimide as copolymer monomer units, and copolymers of styrene and acrylonitrile (AS ). Among them, thermoplastic resins such as ABS resin, polystyrene, and high-impact polystyrene are preferable. The styrene resin (A) has a weight average molecular weight of less than 6.7 million as measured by gel permeation chromatography (GPC), and can be generally produced by a conventional method. Less than ten thousand. For the ABS resin and the like containing a rubbery polymer, the value obtained by measuring the methyl ethyl ketone (MEK) soluble matter by GPC.

Next, the processing aid (B) for a styrenic resin in the present invention will be described. The styrenic resin processing aid (B) is composed of a styrenic polymer having a styrene-based monomer unit of 60% by weight or more and a weight-average molecular weight of 6.7 million or more. Examples of the styrene-based monomer to be used include styrene, α-methylstyrene, vinyltoluene, vinylxylene, vinylnaphthalene and the like, and among them, styrene is preferred.

In the present invention, these styrene monomers can be used alone or in combination of two or more.

The content of the styrenic monomer unit in the styrenic resin processing aid (B) in the present invention is at least 60% by weight, preferably at least 65% by weight. If the content of the styrene-based monomer unit is less than 60% by weight, the dispersion of the processing aid (B) for the styrene-based resin in the styrene-based resin (A) is reduced, and the appearance of a molded article is deteriorated.

Further, a processing aid for styrenic resin (B)
Other vinyl monomers that can be copolymerized with the styrene monomer in the range of 40% by weight or less can be used as optional components constituting the above. Other vinyl monomers are not particularly limited, and include, for example, vinyl cyanide monomers, methacrylate monomers, acrylate monomers, and unsaturated dicarboxylic anhydride monomers. And an imide compound monomer of an unsaturated dicarboxylic acid. Among them, a vinyl cyanide monomer and a methacrylate monomer are preferable. Specifically, vinyl cyanide monomers such as acrylonitrile, methacrylonitrile, and fumaronitrile, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, phenyl methacrylate, Benzyl acrylate, methacrylate monomers such as isobornyl methacrylate, acrylate monomers such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, Maleic acid, itaconic acid, unsaturated dicarboxylic anhydride monomers such as citraconic anhydride, maleimide, N-methylmaleimide, N-butylmaleimide, N-phenylmaleimide, N-cyclohexylmaleimide Include imide compound monomer of saturated dicarboxylic acids, these vinyl monomers may be used alone or in combination of two or more.

In the styrene resin processing aid (B), if the content of these vinyl monomer units as an optional component exceeds 40% by weight, the styrene resin processing aid (B) of the styrene resin Dispersion in the resin (A) decreases, and the appearance of the molded product deteriorates.

In order for the processing aid for styrenic resin (B) to have an excellent thermoforming property imparting effect, it is essential that the molecular weight of the processing aid for styrenic resin (B) be extremely high. It is a necessary condition that the weight average molecular weight measured by gel permeation chromatography (GPC) is 6.7 million or more, and preferably 7 million or more. When the weight average molecular weight is less than 6.7 million, the effect of imparting properties during thermoforming is reduced. Furthermore, the ratio (Mw) between the weight average molecular weight (Mw) and the number average molecular weight (Mn)
/ Mn) is preferably 2.7 or more. Since the molecular weight is extremely high, the compatibility is better when Mw / Mn is 2.7 or more. Particularly preferably, it is 3.0 to 15. Also,
In order to obtain a predetermined molecular weight, polymerization can be carried out by adjusting the amount of a chain transfer agent or catalyst used, the polymerization temperature, and the like during the polymerization method described below.

The above-mentioned processing aid for styrenic resin (B)
A known method can be used as a method for obtaining the polymer. For example, examples of the polymerization method include emulsion polymerization, suspension polymerization, and solution polymerization. Among these, the application of the emulsion polymerization method is preferable. In the production method to which this emulsion polymerization method is applied, known emulsifiers can be used and are not particularly limited. For example, anionic surfactants such as fatty acid salts, alkyl sulfate salts, alkyl benzene sulfonate salts, alkyl acid ester salts, alkyl diphenyl ether sulfonate salts, and polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters And nonionic surfactants such as glycerin fatty acid esters, and cationic surfactants such as alkylamine salts. These emulsifiers can be used alone or in combination. Further, as the polymerization initiator,
Water-soluble, oil-soluble single type, or redox type may be used.For example, an inorganic initiator such as a normal persulfate is used alone or in combination with a sulfite, a hydrogen sulfite, a thiosulfate, or the like. Can be used as a redox initiator. Further, t-butyl hydroperoxide, cumene hydroperoxide, benzoyl peroxide, organic peroxides such as lauroyl peroxide, azo compounds or the like may be used alone or in combination with sodium formaldehyde sulfoxylate and the like, or a redox initiator. Can also be used.

The method of recovering the high molecular weight styrenic resin processing aid (B) used in the present invention after polymerization is, for example, when obtained by emulsion polymerization, the obtained resin processing aid (B) The polymer is cooled to room temperature and acid-coagulated or salted out with an acid such as sulfuric acid, hydrochloric acid, phosphoric acid, or an salt such as aluminum chloride, calcium chloride, magnesium sulfate, aluminum sulfate, calcium acetate, or the like. After precipitating the polymer by filtration, it can be further obtained by filtration, washing and drying. Further, a known recovery method such as recovery of the obtained polymer latex by a technique such as spray drying or freeze drying can be used.

Next, the thermoplastic resin composition of the present invention will be described. The thermoplastic resin composition of the present invention has a styrene-based weight of 60% by weight or more based on 100 parts by weight of the styrene-based resin (A) and a weight average molecular weight of 6.7 million or more. It is a thermoplastic resin composition in which 0.3 to 10 parts by weight of a processing aid (B) for a styrene-based resin composed of a united product is blended. If the amount is less than 0.3 parts by weight, the viscosity of the thermoplastic resin composition cannot be improved, the molding temperature is low, and the processing time is short, but rupture or knitting occurs during blowing,
It is not preferable as a molded article. On the other hand, if it exceeds 10 parts by weight, the viscosity of the thermoplastic resin composition increases, the molding temperature rises, and the processing time becomes longer. Preferably, the processing aid (B) for styrene resin is 0.5 to 5 parts by weight based on 100 parts by weight of styrene resin (A).

To prepare this thermoplastic resin composition,
(1) A method of weighing a predetermined amount of separately produced powdery, flake, bead-like, or pellet-like polymers and melt-mixing them. (2) Preparing separately produced latex-like polymers. Quantitative weighing, mixing and coagulation to make powder,
(3) a method in which the graft polymer (C) and the processing aid for styrene resin (B) are mixed and coagulated in a latex state to form a powder, and the styrene copolymer (a) is melt-mixed with the powder; (4) A method of producing a graft polymer (C) by causing a latex of a processing aid (B) for a styrene-based resin prepared in advance during graft polymerization, and (5) There may be mentioned, for example, a method in which the processing aid (B) for styrenic resin is polymerized and adjusted, followed by graft polymerization to simultaneously produce the processing aid (B) for styrenic resin and the graft polymer (C). However, the present invention is not limited to these.

The method of melt-mixing the components constituting the thermoplastic resin composition of the present invention is not particularly limited, and may be an extruder such as a single screw extruder or a twin screw extruder, or a Banbury mixer, a kneader / ruder. , Pressure kneader,
The resin composition can be melt-mixed using a general known processing device such as a kneader such as a heating roll.

The thermoplastic resin composition of the present invention contains a kind and amount of a lubricant which does not impair the properties of the resin composition of the present invention.
Various resin additives such as mold release agents, coloring agents, antioxidants, ultraviolet absorbers, light resistance stabilizers, heat resistance improvers, fillers, antistatic agents, flame retardants, antibacterial agents, and antifungal agents as required Can be added.

The obtained thermoplastic resin composition can be prepared by a usual known molding method, for example, injection molding, extrusion molding, hollow molding,
Various molded products can be obtained by various molding methods such as press molding. In particular, sheeting by extrusion molding method,
This sheet is suitable for the inner box of an electric refrigerator that is manufactured by a plug-assisted pneumatic / vacuum forming method.

[0043]

The present invention will be described in detail with reference to the following examples and comparative examples, but the present invention is not limited to the following examples. All parts and percentages in Examples and Comparative Examples are based on weight unless otherwise specified. In addition, each physical property in each example and comparative example was measured by the following method.

Each measuring method and evaluation method used in the present invention will be described. (1) Weight average molecular weight The weight average molecular weight of the styrene-based polymer and the styrene-based copolymer was measured using a gel permeation chromatography (GPC) apparatus under the following conditions.
The molecular weight is a value in terms of polystyrene. Apparatus; “SYSTEM-21” column, manufactured by Tosoh Corporation; PLgel MIXED-B temperature; 40 ° C. solvent; tetrahydrofuran detection; RI concentration; 0.2% injection volume; 100 μl calibration curve; standard polystyrene (manufactured by Polymer Laboratories)
Compliant with.

(2) Method for Measuring Volume Average Particle Diameter of Rubber in Rubbery Polymer Latex The particle size distribution of the rubbery polymer of the present invention was determined by a laser diffraction scattering method. The measurement conditions are as follows. Apparatus: COULTERLS 230 (manufactured by COULTER) Concentration: 2.0% Diluent solvent: distilled water Analysis software: Version 2.05

(3) Method of measuring graft ratio The graft ratio of the graft copolymer of the present invention was determined by the following method. About 20 g of a graft polymer (C) latex containing the graft-polymerized styrene copolymer (a) is precipitated and solidified with 100 ml of methanol, and the coagulated product is subjected to suction filtration using a filter paper. The filtrate is dried in a vacuum dryer for 24 hours.
Dry at room temperature. About 1.2 g of the obtained sample was
in a conical flask, and add methyl ethyl ketone (ME
K) After adding 30 g, the mixture was stirred at a temperature of 23 ° C. for 24 hours,
Thereafter, the insoluble matter in MEK was separated by a centrifugal separator, and the mixture was allowed to stand for 30 minutes after the centrifugation operation. The operating conditions of this centrifuge were set as follows. Temperature: -9 ° C Rotation speed: 20,000 rpm Time: 60 minutes The supernatant of the solution subjected to centrifugation and the precipitate were separated, and the precipitate was dried with a vacuum dryer to obtain an insoluble matter X. Further, the weight Y of the acrylonitrile monomer determined by the Kjeldahl nitrogen method using the sample of the insoluble matter and the weight Z of the styrene monomer determined by the pyrolysis gas chromatography.
And the graft ratio (%) = 100 × (Y + Z) / ΔX
− (Y + Z)}.

(4) Pretreatment method for measuring the molecular weight of the styrenic copolymer (a) in the graft polymer (C) When measuring the graft ratio, the supernatant obtained by centrifugation was treated with methanol. The precipitate is placed in a 300 ml beaker containing 150 ml and precipitated, and the precipitate is suction-filtered using a filter paper. The filtrate is dried in a vacuum dryer at room temperature for 24 hours. Using the obtained sample, (1) the weight average molecular weight of the styrene copolymer (a) obtained by graft polymerization was determined by the operation of the weight average molecular weight.

(5) Vacuum Formability Using a thermoplastic resin composition, an extruder with a T-die (VE-40 manufactured by Tanabe Plastics Industry Co., Ltd.) was used to obtain a thickness of 1 mm.
mm sheet, and 400 × 400 mm
mm sheet plate, and cut out using a vacuum forming machine (FK0431).
-10, plug assist type), 270m per side
m, a box-shaped molded product with a depth of 150 mm, a sheet temperature of 150,
Molding was performed at 160 and 170 ° C. The sheet temperature was determined by measuring the temperature distribution of the sheet surface from JEOL Thermoviewer J.
Observation was performed with TG-6300, and the temperature was controlled by a heater so that the surface temperature immediately before blow molding was uniform. The shape of the plug used during molding is 225 m on a side
m, height 140 mm, and R at each corner is 10 mm. In the molding step, the initial blowing time was 2 seconds, the heating was completed, and after 1 second, the blowing was started. The next plug drop started 5.5 seconds after the end of heating. Vacuum forming starts 7 seconds after the end of heating, and
Vacuum was maintained at 30 mmHg for 20 seconds. (A) Uneven thickness ratio: The obtained molded product is cut in the vertical direction from the center of one side of the opening to the center of the bottom, the minimum thickness A at the cut surface is measured, and the thickness B of the sheet molded product is measured. Ratio (B / A)
And its value is shown as the uneven thickness ratio. A smaller thickness deviation ratio means that there is no thickness deviation, which is preferable. (B) Radius of curvature: 1 from the opening at the corner of the molded product to the bottom
The measured value of the radius of curvature R in the direction parallel to the opening with the point having a depth of 25 mm as the center is shown. Radius R of the part of the mold
Since the value is 1.0, the radius of curvature R of the portion is 1.0
It shows that the mold transferability is better as the value is closer to.

(6) High Cycle Moldability A molded article that does not cause uneven thickness when vacuum forming is performed and has good mold transfer properties can be obtained from a low sheet temperature. The lower the temperature, the shorter the molding cycle.

Next, the raw resin used will be described. (1) Production Example of Styrene-Based Copolymer (a) Styrene 30 was placed in a stainless steel autoclave equipped with a stirrer, a heating / cooling device, a thermometer, and a raw material / auxiliary agent adding device.
Parts, 30 parts of acrylonitrile, 0.07 part of calcium tertiary phosphate, 0.6 part of n-dodecylmercaptan, and 100 parts of deionized water, and the inside of the polymerization system was replaced with nitrogen gas. Under stirring, the internal temperature was raised to 96 ° C, and potassium persulfate was added to 0.1 ml.
01 parts were added to initiate the polymerization reaction. Immediately after the start of the polymerization, 40 parts of styrene were continuously added at a constant rate over 7 hours, and the internal temperature was maintained at 96 ° C for 4 hours.
Thereafter, the temperature was raised to 105 ° C. over 30 minutes and maintained for 1.5 hours. The temperature was raised to 115 ° C. over a further 30 minutes and maintained for 3 hours to complete the polymerization. Thereafter, the mixture was cooled, filtered, washed with water, and dried to obtain a beaded styrene-based copolymer. The weight average molecular weight of this polymer was 160,000. This polymer is hereinafter referred to as a-1.

(2) Production Example of Graft Polymer (C) C-1: Production of Rubbery Polymer A stainless steel autoclave equipped with a stirrer, a heating / cooling device, a thermometer, a pressure gauge, and a raw material / auxiliary additive device was prepared. , After nitrogen replacement, butadiene 100 parts, potassium rosinate 2.5
, 0.4 parts of t-dodecylmercaptan, 1.5 parts of potassium carbonate, and 100 parts of deionized water, and the internal temperature was raised to 50 ° C under stirring. When the internal temperature reached 50 ° C., 0.5 part of potassium persulfate was added. An exotherm occurred a few minutes later, confirming the start of polymerization. Internal pressure 1kg / cm ² G
The polymerization was terminated at the time of, and the system was cooled. The obtained rubbery polymer latex had a solid content of 50% and an average particle size of rubber of 0.31 μm.

Production of Graft Polymer In a stainless steel autoclave equipped with a stirrer, a heating and cooling device, a thermometer, and a device for adding raw materials and auxiliaries, 100 parts (as a solid content) of the rubbery polymer latex obtained in the above was deionized. 366 parts of water (including the water content in the latex) were charged, and the inside of the polymerization system was replaced with nitrogen gas.
The temperature rose. When the internal temperature reaches 58 ° C. on the way, 0.005 part of ferrous sulfate heptahydrate, 0.01 part of ethylenediaminetetraacetic acid tetrasodium dihydrate, 0.01 part of formaldehyde / sodium bisulfite 2 in 13 parts of deionized water A solution consisting of 0.3 parts of water salt was added. When the internal temperature reaches 60 ° C., a monomer mixture comprising 70 parts of styrene, 30 parts of acrylonitrile, 0.1 part of 2,4-diphenyl-4-methyl-1-pentene and 27 parts of deionized water, Fatty acid soap 1.5
And a solution consisting of 0.4 part of diisopropylbenzene hydroperoxide were continuously added, and the process was completed in 6 hours. Thereafter, the reaction was continued at a temperature of 70 ° C. for 2 hours, and then the internal temperature was cooled. The solid content of the obtained graft polymer latex was 33.0%. An antioxidant (1.5 parts) was added to the obtained mixed latex, and the latex was added to an aqueous magnesium sulfate solution heated to a temperature of 95 ° C. to coagulate, filtered, washed and dried to obtain a white powdery resin composition. I got This graft polymer is designated as C-1. The graft ratio of the graft polymer C-1 was 85.1%,
The weight average molecular weight of the ungrafted copolymer was 175,000.

C-2: Production of Rubbery Polymer After replacing with nitrogen in a stainless steel autoclave equipped with a stirrer, a heating / cooling device, a thermometer, a pressure gauge, and a raw material / auxiliary additive device, 95 parts of butadiene and 5 parts of styrene were used. Then, 3.0 parts of potassium rosinate, 0.3 part of t-dodecyl mercaptan, 1.5 parts of dibasic sodium phosphate and 70 parts of deionized water were charged, and the internal temperature was raised to 55 ° C. with stirring. When the internal temperature reached 55 ° C., 0.5 part of ammonium persulfate was added. An exotherm occurred a few minutes later, confirming the start of polymerization.
When the internal pressure reaches 1 kg / cm ² G, the polymerization is terminated,
Cool. The obtained rubber-like polymer latex had a solid content concentration of 50% and an average particle size of the rubber of 0.65 μm.

Production of Graft Polymer In a stainless steel autoclave equipped with a stirrer, a heating / cooling device, a thermometer, and a device for adding raw materials and auxiliaries, the rubbery polymer latex obtained was mixed at a solid content weight ratio of 2: 1. 100 parts (as solid content) mixed in a ratio of
7.5 parts, 7.5 parts of acrylonitrile, and 366 parts of deionized water (including the water content in latex) were charged, the inside of the polymerization system was replaced with nitrogen gas, and the internal temperature was raised to 60 ° C under stirring. 6
Stirred at 0 ° C. for 30 minutes. When the internal temperature reached 58 ° C. on the way, 13 parts of deionized water contained 0.005 ferrous sulfate heptahydrate.
Parts, ethylenediaminetetraacetic acid tetrasodium dihydrate 0.0
A solution consisting of 1 part and 0.3 part of formaldehyde / sodium bisulfite dihydrate was added. When the internal temperature reaches 60 ° C., 27 parts of deionized water and 1.5 parts of a higher fatty acid soap
And a solution consisting of 0.4 part of diisopropylbenzene hydroperoxide was continuously added and completed in 6 hours. After stirring at a temperature of 60 ° C. for 30 minutes, styrene 52.
A continuous addition of a solution consisting of a monomer mixture consisting of 5 parts, 22.5 parts of acrylonitrile and 0.1 part of 2,4-diphenyl-4-methyl-1-pentene was started and ended in 6 hours. Then, after continuing the reaction at a temperature of 70 ° C. for 2 hours,
The internal temperature was cooled. The solid content of the obtained graft polymer latex was 33.0%. An antioxidant (1.5 parts) was added to the obtained mixed latex, and the latex was added to an aqueous magnesium sulfate solution heated to a temperature of 95 ° C. to coagulate, filtered, washed and dried to obtain a white powdery resin composition. I got This graft polymer is designated as C-2. In addition,
The graft ratio of the graft polymer C-2 was 35.8%, and the weight-average molecular weight of the ungrafted copolymer was 86,000.

(3) Example of Processing Aid (B) for Styrenic Resin B-1 65 parts of styrene were placed in a stainless steel autoclave equipped with a stirrer, a heating / cooling device, a thermometer, and a raw material / aid adding device. 30 parts of acrylonitrile, 0.01 part of 2,4-diphenyl-4-methyl-1-pentene, 2 parts of semi-cured fatty acid potassium soap, and 150 parts of deionized water were charged, the inside of the polymerization system was replaced with nitrogen gas, and the mixture was stirred. , And the mixture was heated and stirred for 4 hours and 30 minutes. In addition, styrene 5
And 0.1 part of diisopropylbenzene hydroperoxide were continuously added over 30 minutes. After the addition was completed, the temperature was raised to 70 ° C., the reaction was continued for another 2 hours, and the reaction was terminated by cooling. An aqueous magnesium sulfate solution was added to the obtained latex for coagulation, followed by filtration, washing and drying to obtain a styrene polymer B-1. The weight average molecular weight of this polymer was 7.03 million, and Mw / Mn was 4.6.

B-2: The reaction vessel used in Example 1 was charged with 20 parts of styrene, 10 parts of acrylonitrile, 1.5 parts of semi-cured fatty acid potassium soap, and 127 parts of deionized water, and the inside of the polymerization system was replaced with nitrogen gas. Then, the temperature was raised to 65 ° C. under stirring. After adding 0.05 parts of potassium persulfate, a monomer mixture composed of 40 parts of styrene and 20 parts of acrylonitrile was continuously added at a constant rate over 6 hours. 30 minutes after the start of continuous addition, 0.005 part of ferrous sulfate heptahydrate, 0.01 part of ethylenediaminetetraacetic acid tetrasodium dihydrate, 0.01 part of formaldehyde / sodium bisulfite dihydrate in 13 parts of deionized water 3 parts solution and deionized water 4
To 0 parts, 1.0 part of the semi-cured fatty acid potassium soap and a solution comprising potassium persulfate were continuously added at a constant rate over 6 hours. Further, 10 parts of styrene and 0.1 part of diisopropylbenzene hydroperoxide were continuously added over 30 minutes. After the addition was completed, the temperature was raised to 70 ° C., the reaction was continued for another 2 hours, and the reaction was terminated by cooling. An aqueous magnesium sulfate solution was added to the obtained latex to coagulate,
After filtration, washing and drying, a styrene polymer B-2 was obtained.
The weight average molecular weight of this polymer was 8.07 million and Mw / Mn
Was 5.1.

B'-3: In B-1, 0.01 part of 2,4-diphenyl-4-methyl-1-pentene charged in the autoclave was changed to 0.08 part of n-dodecylmercaptan, and 65 parts of styrene and Acrylonitrile 30
The procedure was performed in the same manner as for B-1 except that the part was changed to continuous addition for 4 hours and 30 minutes. The weight average molecular weight of this polymer is 76
It was 10,000.

Examples 1 to 3 and Comparative Examples 1 to 3 The styrene-based copolymer (a), the graft polymer (C) and the processing aid (B) for styrene-based resin described above were weighed as shown in Table 1. Parts were kneaded and pelletized in a twin-screw extruder.

Using the pellets, a sheet was formed by an extruder according to the results of the measurement under the physical property measurement conditions described above and the evaluation method described above, and the vacuum formability of the sheet was evaluated. Table 1 shows the results.

[0060]

[Table 1]

The following becomes clear from Table 1. By adding the processing aid for styrenic resin according to the present invention, a molded product having a wide range of molding suitability, less uneven thickness, and good mold transferability when vacuum forming is obtained (Examples 1 to 5).
3). On the other hand, the thermoplastic resin composition of the comparative example, which does not satisfy the essential requirements of the present invention, has a large knit (Comparative Examples 1 and 2), poor mold transferability (Comparative Example 3), The range is narrow and good vacuum molded products cannot be obtained.

[0062]

As described above, the thermoplastic resin composition obtained by blending the styrenic resin processing aid of the present invention with a styrenic resin can be subjected to thermoforming, especially vacuum forming, using a sheet of the thermoplastic resin composition as described above. When molding into the desired shape by molding methods such as molding and pressure forming, the molding cycle can be shortened, the appropriate temperature range for molding is wide, and when molding into the desired shape, the uneven thickness is small and the effect of excellent mold transferability is achieved. And its industrial value is extremely large.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 51/04 C08L 51/04 55/02 55/02 // B29K 25:00 B29L 7:00 F term ( Reference) 4F071 AA22 AA77 AA81 AH12 BA01 BB03 BB05 BB06 BC01 4F207 AA13E AG01 AH33 AH51 KA01 KA17 KF01 KL84 KW41 4F208 AA13E AG01 AH33 AH51 MA03 MG22 MJ09 4J002 BC06X ABC3B07B13 A0713 BC07X13 BC07X07 BC07 BC08 BA05 BA27 BA31 DB04 GA03 GA04

Claims (6)

[Claims] 1. A styrene resin comprising a styrene polymer having a styrene monomer unit content of 60% by weight or more and a weight average molecular weight of 6.7 million or more based on 100 parts by weight of the styrene resin (A). Processing aid (B) 0.3 to 10
A thermoplastic resin composition characterized by blending parts by weight. 2. A styrene-based resin (A) comprising a styrene-based monomer, a vinyl cyanide-based monomer, and optionally a monomer comprising a vinyl-based monomer copolymerizable with these monomers. A continuous phase of a styrene-based copolymer (a) obtained by polymerizing the mixture, and a styrene-based monomer, a vinyl cyanide-based monomer, and in some cases, copolymerization with these monomers in a rubber-like polymer The graft branches of a copolymer comprising a monomer mixture of possible vinyl monomers consist of a dispersed phase of a graft copolymer (b) obtained by graft polymerization, and this continuous phase of a styrene copolymer ( The thermoplastic resin composition according to claim 1, wherein the weight average molecular weight of a) is from 50,000 to 300,000. 3. The weight ratio of the continuous phase styrene copolymer (a) and the dispersed phase graph copolymer (b) constituting the styrene resin (A) is 50 to 85:50 to 15 by weight. 3. The thermoplastic resin composition according to claim 1, wherein the content is in the range of% by weight. 4. A styrene monomer and a vinyl cyanide monomer in the continuous phase styrene copolymer (a) and the dispersed phase graft copolymer (b) constituting the styrene resin (A). And the proportion of the vinyl monomer copolymerizable therewith, if necessary, is 60 to 80:15 to 4 by weight.
The thermoplastic resin composition according to claim 2 or 3, wherein the ratio is in the range of 5: 0 to 20 (where the total of the monomers is 100% by weight). 5. A sheet obtained by extrusion molding using the thermoplastic resin composition according to claim 1. 6. A molded product obtained by vacuum forming the extruded sheet according to claim 5.