JP2001207015A - Thermoplastic resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a styrene-based resin composition which enhances fabricability in vacuum forming and compressive air forming by the use of an extruded film of the styrene-based resin composition. SOLUTION: The thermoplastic resin composition is obtained by mixing a processing aid (B) for a styrene-based resin composed of a styrene-based polymer containing a styrene-based monomer unit of not less 60 mass %, the styrene-based polymer having a weight average molecular weight from more than 5,000,000 to less than 6,700,000 and Mw/Mn of not less than 2.5, with 100 pts.wt. of a styrene-based resin (A) containing a methyl ethyl ketone-soluble component having a weight average molecular weight of not more than 1,000,000.

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 an inner box molded product includes the steps of heating a sheet, blowing by air injection, forcibly stretching with a plug, transferring a mold by vacuum suction / pressure, cooling, and releasing the molded product. In this case, if the heating of the sheet (radiant heat) and deformation due to its own weight increase, in extreme cases, contact with the device may occur, or the distance between the deformed portion and the heater may decrease, and 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 Can not be molded,
The radius of curvature of the portion of the molded article is increased.

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, and after stretching processing, is cooled to 100 ° C. or lower to form a molded article. Since the heating and cooling time is short, the time for the entire process from heating the sheet to cooling the molded product can be shortened, and the productivity per unit time can be improved.

[0010] 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,
Heat is radiated 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. Mold transfer,
If it 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.

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 The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, it has been found that a specific molecular weight and a value of Mw (weight average molecular weight) / Mn (number average molecular weight) are given to the styrene resin. By blending an ultra-high molecular weight styrene-based polymer having a styrene-based polymer as a processing aid, it is possible to obtain a thermoplastic resin composition having improved thermoformability of a sheet produced by an extrusion molding method of a styrene-based resin. This led to the present invention.

That is, the present invention is a thermoplastic resin composition obtained by mixing 0.5 to 15 parts by mass of the component B with 100 parts by mass of the following component A. The component A is a styrene-based resin (A) having a weight-average molecular weight of 1,000,000 or less of a methyl ethyl ketone-soluble component, and the component B is a polymer mainly containing 60% by mass or more of a styrene-based monomer unit. And the weight average molecular weight of this polymer is
It is a processing aid (B) for a styrenic resin composed of a styrenic polymer having a Mw / Mn smaller than 10,000 and a Mw / Mn larger than 2.5.

The present invention further relates to a styrene-based resin (A) as the component A, wherein the styrene-based monomer, vinyl cyanide-based monomer and, if necessary, a vinyl-based monomer copolymerizable with these monomers. Continuous phase of a styrene copolymer (a) obtained by polymerizing a monomer mixture of a monomer, and a styrene monomer, a vinyl cyanide monomer, and A graft phase of a graft copolymer (b) obtained by graft-polymerizing a graft branch of a copolymer comprising a monomer mixture of a vinyl monomer copolymerizable with the above-mentioned monomer; Is a thermoplastic resin composition in which the weight average molecular weight of the styrene copolymer (a) is 50,000 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 mass ratio.
To 15% by mass, more preferably, a graft copolymer of a continuous phase styrene copolymer (a) and a dispersed phase satisfying the above requirements and constituting the styrene resin (A) ( The proportion of the styrene-based monomer, vinyl cyanide-based monomer and, if necessary, the monomer copolymerizable therewith in b) is from 60 to 80:15 to 45:
0-20 (however, the total of the monomers is 100% by mass
It is. ) Is a thermoplastic resin composition.

Hereinafter, the present invention will be described in detail. The styrene resin (A) of the component A of the present invention includes a styrene monomer, a vinyl cyanide monomer and, if necessary, a vinyl monomer copolymerizable with these monomers. A vinyl cyanide-based monomer, a styrene-based monomer, and optionally these monomers are added to a continuous phase and a rubbery polymer of a styrene-based copolymer (a) obtained by polymerizing a monomer mixture. Graft copolymer (b) obtained by graft-polymerizing a graft branch of a copolymer comprising a monomer mixture of copolymerizable vinyl monomers.
Is preferred.

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. These copolymerizable monomers used as needed include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, phenyl methacrylate, benzyl methacrylate, and the like. Methacrylate monomers such as isobornyl acrylate; acrylate monomers such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and cyclohexyl acrylate; maleic acid , Itaconic acid, citraconic acid and other unsaturated dicarboxylic acid monomers and anhydrides thereof, maleimide, N-methylmaleimide, N-butylmaleimide, N
And imide compound monomers of unsaturated dicarboxylic acids such as -phenylmaleimide and N-cyclohexylmaleimide. 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. A latex-like rubbery polymer is used, and 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 mass of the monomer mixture in the presence of 30 to 60% by mass 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 benzene sulfonates, alkyl ester sulfonates, alkyl diphenyl ether sulfonates, polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, glycerin fatty acid esters For example, a nonionic surfactant such as a nonionic surfactant and a cationic surfactant such as an alkylamine salt can be used. 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 mass 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 ratio of the styrenic copolymer (a) to the graft copolymer (b) is 50 to 85 by mass ratio.
It is preferably in the range of 50 to 15% by mass. 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-based monomer, vinyl cyanide-based monomer and, if necessary, the monomer copolymerizable therewith in the graft copolymer (b) is 60 to 80: 1 by mass.
5 to 45: 0 to 20 (where the total number of monomers is 1
00% by mass. ) 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 another monomer copolymerizable therewith, if necessary, are added in the presence of a polymerization initiator and, if necessary, a chain transfer agent. And a method of producing by 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 weight average molecular weight of these styrene resins (A) is such that the weight average molecular weight of the methyl ethyl ketone soluble component is 1,000,000 or less. The weight-average molecular weight of a methyl ethyl ketone-soluble component is a weight-average molecular weight measured by gel permeation chromatography (GPC) of an extract extracted at a temperature of 23 ° C., a concentration of 5% and an extraction time of 24 hours using methyl ethyl ketone as a solvent. Molecular weight.
If it exceeds 1,000,000, the moldability will be poor.

Next, the processing aid (B) for a styrene resin which is the component B in the present invention will be described. The styrenic resin processing aid (B) is a polymer mainly composed of 60% by mass or more of styrene-based monomer units, and has a weight average molecular weight of more than 5,000,000 and more than 6.7,000,000. It is made of a styrene polymer having a small Mw / Mn of more than 2.5. 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 styrenic 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 mass, preferably at least 65% by mass. If the content of the styrene-based monomer unit is less than 60% by mass, 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 which can be copolymerized with the styrene monomer in the range of 40% by mass or less can be used as an optional component constituting the above. The other vinyl monomers are not particularly limited, and include, for example, vinyl cyanide monomers, methacrylate monomers, acrylate monomers, unsaturated dicarboxylic acid monomers, and the like. Anhydride monomers, and imide compound monomers of unsaturated dicarboxylic acids, and the like.
Methacrylate monomers are preferred. In particular,
Acrylonitrile, methacrylonitrile, vinyl cyanide monomers such as fumalonitrile, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate,
Methacrylate monomers such as phenyl methacrylate, benzyl methacrylate, and isobornyl methacrylate; and acrylic acids such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and cyclohexyl acrylate Ester monomers, maleic acid, itaconic acid, unsaturated dicarboxylic acid monomers such as citraconic acid and anhydrides thereof, maleimide, N-methylmaleimide, N-butylmaleimide, N-phenylmaleimide, N-cyclohexylmaleimide Examples include unsaturated dicarboxylic acid imide compound monomers, and these vinyl monomers are used alone or
Alternatively, two or more kinds can be used in combination.

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

In order for the processing aid (B) for styrenic resin to have an excellent thermoforming property imparting effect, it is essential that the molecular weight of the processing aid (B) for styrenic resin be extremely high. It is a necessary condition that the weight average molecular weight measured by gel permeation chromatography (GPC) is larger than 5 million and smaller than 6.7 million. When the weight average molecular weight is 5,000,000 or less, the effect of imparting properties during thermoforming becomes small. Furthermore, Mw
/ Mn is preferably greater than 2.5. Since the processing aid (B) for styrene-based resin is of an ultra-high molecular weight, Mw / Mn greater than 2.5 has better compatibility. Particularly preferably, it is 3.0 to 15. In order to obtain a predetermined molecular weight,
In the polymerization method described below, polymerization can be carried out by adjusting the amount of the chain transfer agent or catalyst used, the polymerization temperature, and the like.

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, fatty acid salts, alkyl benzene sulfonates, alkyl ester sulfonates,
Anionic surfactants such as alkyl diphenyl ether sulfonates, nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, and glycerin fatty acid esters, and cations such as alkylamine salts Anionic surfactants can be used. Also,
These emulsifiers can be used alone or in combination. Further, the polymerization initiator may be a water-soluble, oil-soluble single type, or a redox type, for example, a single inorganic initiator such as a normal persulfate, or a sulfite, hydrogen sulfite It can also be used as a redox initiator in combination with a salt, thiosulfate, or the like. Further, t-butyl hydroperoxide,
Organic peroxides such as cumene hydroperoxide, benzoyl peroxide and lauroyl peroxide, azo compounds and the like can be used alone or in combination with sodium formaldehyde sulfoxylate or the like and used as a redox initiator.

The method of recovering the high molecular weight styrenic resin processing aid (B) used in the present invention after polymerization may be, 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 comprises the following A component 1
A thermoplastic resin composition obtained by mixing 0.5 to 15 parts by mass of the component B with respect to 00 parts by mass, and the component A is a styrene-based resin having an acetone-soluble component having a weight average molecular weight of 1,000,000 or less ( The components A) and B are styrene-based monomer units in an amount of 60% by mass or more, and have a weight average molecular weight of more than 5,000,000 and less than 6.7 million, and Mw (weight average molecular weight) / Mn
It is a processing aid (B) for a styrenic resin comprising a styrenic polymer having a (number average molecular weight) larger than 2.5. If the B component is less than 0.5 part by mass, 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, resulting in a molded article. Is not preferred. On the other hand, if the amount exceeds 15 parts by mass, the viscosity of the thermoplastic resin composition increases, the molding temperature increases, and the processing time is undesirably increased. Preferably, the processing aid (B) is 2.0 to 10 parts by mass based on 100 parts by mass of the 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.

[0044]

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 the examples and comparative examples are based on mass 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)
It was produced using.

(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 for 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. Furthermore, the mass Y of the acrylonitrile monomer determined by the Kjeldahl nitrogen method using the sample of the insoluble matter and the mass 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 the centrifugation operation was replaced 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 and a thickness of 1 using an extruder with a T-die (VE-40 manufactured by Tanabe Plastics Industry Co., Ltd.)
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 process, after the predetermined temperature was reached, blowing was performed for 2 seconds, and blowing was further maintained for 1 second. The next plug drop started 5.5 seconds after the end of heating. Vacuum forming starts 7 seconds after the end of heating, and is -730.
The vacuum was maintained at 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 Formability A molded article which does not cause uneven thickness when vacuum forming is performed and has good mold transferability can be obtained from a low sheet temperature. The lower the temperature, the shorter the molding cycle.

Next, the raw material 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 In a stainless steel autoclave equipped with a stirrer, a heating / cooling device, a thermometer, a pressure gauge, and a raw material / auxiliary agent adding device. , 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 / cooling device, a thermometer, and a device for adding raw materials and auxiliaries, 100 parts (as 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 The rubbery polymer latex obtained in a stainless steel autoclave equipped with a stirrer, a heating / cooling device, a thermometer, and a raw material / auxiliary agent adding device was mixed at a solid content mass 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 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 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%. To the obtained mixed latex, 1.5 parts of an antioxidant was added, and then the latex was heated to a temperature of 95%.
The mixture was added to an aqueous solution of magnesium sulfate heated to ℃ and solidified, filtered, washed and dried to obtain a white powdery resin composition. This graft polymer is designated as C-2. 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) Production Example of Processing Aid (B) for Styrenic Resin B-1: 75 parts of styrene were placed in a stainless steel autoclave equipped with a stirrer, a heating / cooling device, a thermometer, and a raw material / auxiliary agent adding device. Acrylonitrile 25 parts, higher fatty acid soap 2
0 parts and 2,000 parts of deionized water were charged, the inside of the polymerization system was replaced with nitrogen gas, and the temperature was raised to an internal temperature of 40 ° C. with stirring. When the internal temperature reached 40 ° C., 0.005 part of ferrous sulfate heptahydrate, 0.01 part of ethylenediaminetetraacetic acid tetrasodium dihydrate, 0.01 part of formaldehyde / sodium bisulfite dihydrate in 26 parts of deionized water Add a solution consisting of 0.3 parts, and keep the internal temperature 40
C. and maintained in t-butyl hydroperoxide 0.00
The polymerization was carried out by heating and stirring for 4 hours and 30 minutes while continuously dropping 6 parts, 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 is 5.3 million, and Mw / Mn is 10.
It was 2.

B-2: 70 parts of styrene and 30 parts of methyl methacrylate were added to the reaction vessel used in the production example of B-1.
, 15 parts of a higher fatty acid soap and 8000 parts of deionized water, and the inside of the polymerization system was replaced with nitrogen gas.
The temperature rose. When the internal temperature reaches 50 ° C., 0.005 part of ferrous sulfate heptahydrate, 0.01 part of ethylenediaminetetraacetic acid tetrasodium dihydrate and 0.01 part of formaldehyde / sodium bisulfite dihydrate are added to 26 parts of deionized water. A solution consisting of 0.3 part was added, and while maintaining the internal temperature at 50 ° C., 0.02 part of t-butyl peroxyacetate was continuously added dropwise with stirring for 4 hours and 30 minutes to carry out polymerization, and the reaction was terminated by cooling. did. 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-2.
I got The weight average molecular weight of this polymer is 6.60 million and M
w / Mn was 7.2.

B-3: 2.0 parts of a higher fatty acid soap and 80 parts of deionized water were charged into the reaction vessel used in the production example of the above B-1, and the inside of the polymerization system was replaced with nitrogen gas. Warm 70
The temperature was raised to ° C. When the internal temperature reached 70 ° C, 0.005 part of ferrous sulfate heptahydrate, 0.01 part of ethylenediaminetetraacetic acid tetrasodium dihydrate, 0.01 part of formaldehyde / sodium bisulfite dihydrate in 26 parts of deionized water A 0.3 part solution was added, and styrene 70 was added while maintaining the internal temperature at 70 ° C.
Parts, 30 parts of acrylonitrile and 0.1 part of potassium persulfate were continuously added while stirring for 4 hours and 30 minutes to carry out polymerization.
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-3. The weight average molecular weight of this polymer was 1.7 million, and Mw / Mn was 8.5.

B-4: 20.0 parts of a higher fatty acid soap and 80 parts of deionized water were charged into the reaction vessel used in the above Production Example B-1, and the inside of the polymerization system was replaced with nitrogen gas. On 4
The temperature was raised to 0 ° C. While maintaining the internal temperature at 40 ° C., polymerization was carried out while continuously dropping 75 parts of styrene, 25 parts of acrylonitrile, and 0.023 parts of t-butyl hydroperoiside for 2 hours, followed by stirring at 40 ° C. for 3 hours, and then cooling. The reaction was terminated. 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-4. The weight average molecular weight of this polymer was 650,000, and Mw / Mn was 2.6.

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 in the above were added in the amounts shown in Table 1. Parts were kneaded and pelletized in a twin-screw extruder.

Using the pellets, a sheet was formed using 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.

[0062]

[Table 1]

The following becomes clear from Table 1. By adding the processing aid for styrene-based resin according to the present invention, a molded product having a wide range of molding suitability, a small thickness deviation, and good mold transferability can be obtained in vacuum molding (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.

[0064]

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.

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Claims (6)

[Claims] 1. A method according to claim 1, wherein 100 parts by weight of component A
A thermoplastic resin composition comprising 0.5 to 15 parts by mass of a component. A component: a styrene-based resin (A) having a weight-average molecular weight of 1,000,000 or less of a methyl ethyl ketone-soluble component, and B component: a polymer mainly composed of 60% by mass or more of a styrene-based monomer unit. A processing aid for styrenic resin (B) comprising a styrenic polymer having a weight average molecular weight of more than 5,000,000 and less than 6.7 million and a Mw (weight average molecular weight) / Mn (number average molecular weight) of more than 2.5 ). 2. A monomer comprising a styrene-based resin (A) comprising a styrene-based monomer, a vinyl cyanide-based monomer, and optionally a vinyl-based monomer copolymerizable with these monomers. Phase of a styrene copolymer (a) obtained by polymerizing a polymer mixture, and a styrene monomer, a vinyl cyanide monomer, and if necessary, A graft branch of a copolymer comprising a monomer mixture of copolymerizable vinyl monomers comprises a dispersed phase of a graft copolymer (b) obtained by graft polymerization, and a styrene copolymer of this continuous phase is formed. The thermoplastic resin composition according to claim 1, wherein the weight average molecular weight of the united product (a) is 50,000 to 300,000. 3. The mass ratio of the continuous phase styrene copolymer (a) and the dispersed phase graph copolymer (b) constituting the styrene resin (A) is 50-85: 50-15. 3. The thermoplastic resin composition according to claim 1, wherein the content is in the range of mass%. 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 mass ratio.
The thermoplastic resin composition according to claim 2 or 3, wherein the ratio is in the range of 5: 0 to 20 (the total of the monomers is 100% by mass). 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.