JP2002348428A - Resin composition for calender processing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition for calender processing capable of forming a good surface appearance without generating dent on the surface of a sheet obtained by calendering and insuring good impact resistance and heat resistance. SOLUTION: The resin composition comprises 100 pts.wt. of an impact resistant polystyrene resin, 0.5-10 pts.wt. of a slipping agent, and 8-40 pts.wt. of MBS copolymer (methyl methacrylate-butadiene rubber-styrene copolymer) fine particles having an average particle diameter of 1200 angstrom or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polystyrene resin composition for calendering, which can form a good surface appearance without causing depressions on the surface of a sheet obtained by calendering.

[0002]

2. Description of the Related Art Impact-resistant polystyrene resins are excellent in mechanical properties, electrical properties, heat resistance, impact resistance, adhesiveness, and heat workability. , Are often used as food containers and the like.

Conventionally, when extruding this impact-resistant polystyrene resin into a sheet, an extrusion molding method or an injection molding method has been used, and it has hardly been produced by a calender molding method.

[0004]

This is because when calendering is performed, the sheet rolled by the metal roll must be peeled off from the metal roll with an appropriate release property. Because the resin has strong adhesion to the metal roll, the rolled sheet becomes difficult to peel off from the metal roll, and thus a sheet with a good surface appearance was not obtained by calender molding of the impact-resistant polystyrene resin. It is.

Of course, in order to improve this releasability,
Although the addition of a lubricant to the impact-resistant polystyrene resin is considered, the addition of this lubricant improves the releasability itself from the metal roll, but the impact-resistant polystyrene resin generally has a viscosity when melted. Low, only by adding a lubricant, bubbles mixed in the impact-resistant polystyrene resin at the time of melt-kneading are likely to remain when being rolled by a metal roll, so that a depression is formed on the surface of the sheet obtained by calendering. However, there is a problem that it is difficult to obtain a sheet having a good surface appearance.

The calender molding method has the advantage of being more economical in production efficiency than the extrusion molding method and the injection molding method. Although it has been strongly desired to produce by the method described above, the fact is that it has not yet been realized industrially due to the above-mentioned problems.

The present invention has been made in view of such a technical background, and it is possible to form a good surface appearance without generating depressions on the surface of a sheet obtained by calendering, and to provide an excellent surface appearance. It is an object of the present invention to provide a calendering resin composition capable of securing impact resistance and heat resistance.

[0008]

Means for Solving the Problems In order to achieve the above object, the present inventors have made intensive studies and as a result, added a specific amount of a lubricant to an impact-resistant polystyrene resin, and further added an average particle size. Prevents the formation of pits on the surface of the calendered sheet without lowering the excellent impact resistance and heat resistance of the impact-resistant polystyrene resin by including a specific amount of specific graft copolymer fine particles in a specific range. They have found what they can do and have completed this invention.

That is, the calendering resin composition according to the present invention comprises 0.5 to 10 parts by weight of a lubricant, 100 parts by weight of an impact-resistant polystyrene resin, and a styrene compound and an alkyl (meth) acrylate. A copolymer obtained by copolymerizing at least one compound selected from the group consisting of butadiene, or butadiene rubber is used as a core polymer, and the core polymer has an alkyl group having 1 to 4 carbon atoms. Alkyl acrylate, alkyl acrylate having 1 to 8 carbon atoms in the alkyl group,
A graft copolymer obtained by graft-polymerizing at least one monomer selected from the group consisting of acrylonitrile and a styrene-based compound in one or more stages, wherein the graft copolymer has an average particle size of 1200 angstroms or more. It is characterized by containing 8 to 40 parts by weight of fine particles.

Since an impact-resistant polystyrene resin is used as the main resin, a calender molded article excellent in both impact resistance and heat resistance can be obtained. Further, since the lubricant is contained in a specific amount, the releasability from the calender roll is excellent. Furthermore, since the specific graft copolymer fine particles are blended in a specific amount, the occurrence of depressions on the sheet surface during calendering can be effectively prevented without lowering the heat resistance. In addition, since the average particle diameter of the specific graft copolymer fine particles is specified to be 1200 Å or more, the above-described excellent effects (dents) can be obtained without deteriorating the excellent impact resistance of the impact-resistant polystyrene resin. (Generation prevention effect).

The average particle size of the graft copolymer fine particles is preferably from 1500 to 3000 angstroms. By defining the average particle size in such a range, it is possible to reliably prevent the occurrence of depressions on the sheet surface.

Further, as the graft copolymer fine particles,
It is preferable to use fine particles of methyl methacrylate-butadiene rubber-styrene copolymer (MBS copolymer), whereby the occurrence of depressions on the sheet surface can be reliably prevented.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The calendering resin composition of the present invention comprises a specific amount of a lubricant and a specific graft copolymer having an average particle size in a specific range with respect to 100 parts by weight of an impact-resistant polystyrene resin. The particles contain a specific amount of fine particles.

The impact-resistant polystyrene resin (HIPS)
The term “resin” refers to a resin obtained by adding a rubber component to polystyrene. Examples of the content form of the rubber component include addition and copolymerization, and the production method thereof includes a polymer blend method (a simple mixing method, a latex method). Mixing method),
A typical example is a graft copolymerization method (emulsion polymerization method, bulk polymerization method, bulk suspension polymerization method, etc.). Examples of the rubber component include butadiene rubber and styrene-butadiene rubber. Specifically, for example, a resin obtained by graft polymerization of styrene to butadiene rubber can be exemplified.

The specific graft copolymer is a copolymer obtained by copolymerizing at least one compound selected from the group consisting of styrene compounds and alkyl (meth) acrylates with butadiene. Alternatively, butadiene rubber is used as a core polymer, and the core polymer is formed from an alkyl methacrylate having 1 to 4 carbon atoms in an alkyl group, an alkyl acrylate having 1 to 8 carbon atoms in an alkyl group, acrylonitrile and a styrene compound. A graft copolymer obtained by graft-polymerizing at least one monomer selected from the group consisting of one or more steps.
The “one or more stages” means that the at least one monomer is graft-polymerized in one or more steps (processes). In addition, examples of the styrene-based compound include styrene, α-methylstyrene, and vinyl toluene.

Above all, it is preferable to use a methyl methacrylate-butadiene rubber-styrene copolymer (MBS copolymer) as the specific graft copolymer. This MBS copolymer is a graft copolymer obtained by graft-polymerizing methyl methacrylate and styrene in one or more stages with butadiene rubber as a core polymer (methyl methacrylate and styrene form a shell). , This M
If a BS copolymer is used, the occurrence of depressions on the sheet surface during calendering can be reliably prevented.

In the resin composition of the present invention, the content of the specific graft copolymer fine particles must be 8 to 40 parts by weight based on 100 parts by weight of the impact-resistant polystyrene resin. If the amount is less than 8 parts by weight, air bubbles mixed in the resin composition during the melt-kneading are likely to remain when being rolled by a calender roll, whereby dents are generated on the surface of the sheet obtained by calendering, and Bad appearance. On the other hand, if it exceeds 40 parts by weight, the occurrence of dents on the sheet surface is prevented, but the heat resistance of the obtained sheet is significantly reduced. Above all, the content of the specific graft copolymer fine particles is determined by the impact-resistant polystyrene resin 10
The amount is preferably from 15 to 40 parts by weight, more preferably from 15 to 25 parts by weight, based on 0 parts by weight.

As the specific graft copolymer fine particles, those having an average particle diameter of 1200 Å or more must be used. If the thickness is less than 1200 angstroms, dents on the sheet surface after calendering caused by remaining bubbles are prevented, but the impact resistance of the obtained sheet is significantly reduced. Among them, the average particle size of the specific graft copolymer fine particles is preferably set in the range of 1500 to 3000 Å, since it is possible to reliably prevent the occurrence of pits, and a more preferable range is 1500 to 2500 Å. is there.

In the resin composition of the present invention, the content of the lubricant must be 0.5 to 10 parts by weight based on 100 parts by weight of the impact-resistant polystyrene resin. If the amount is less than 0.5 part by weight, sufficient releasability from the roll is not imparted to the formed sheet during calendering, and the formed sheet cannot be peeled from the calender roll. On the other hand, if it exceeds 10 parts by weight, the releasability of the roll of the formed sheet becomes excessively good during calendering, and a gap (gap) is easily generated between the roll and the formed sheet. The surface of the sheet is depressed. Among them,
The content of the lubricant is preferably 1 to 5 parts by weight based on 100 parts by weight of the impact-resistant polystyrene resin.

The lubricant is not particularly limited, but one or more lubricants selected from the group consisting of metal soaps, fatty acid esters, fatty acid amides, and methacrylic acid ester / acrylic acid ester copolymers. Is preferred in that the above effect (the effect of preventing the occurrence of dents) can be further enhanced.

As the metal soap, for example, barium,
Calcium, zinc, magnesium, lead or cadmium stearate, or a laurate thereof.

Examples of the fatty acid esters include lower alcohol esters of fatty acids, polyhydric alcohol esters of fatty acids, and fatty acid polyglycol esters. More specifically, lower alcohol esters of fatty acids include, for example, ethyl palmitate, butyl stearate and the like, and polyhydric alcohol esters of fatty acids include, for example, hydrogenated castor oil and the like. Examples of the ester include ethylene glycol monostearate and propylene glycol monostearate.

Examples of the fatty acid amide include stearic acid amide, ethylenebisstearamide, and alkylenebisfatty acid amide.

The methacrylate / acrylate copolymer is not particularly limited, but preferably has a weight average molecular weight of 300,000 to 500,000. Examples of the methacrylate monomer in the above copolymer include, for example, methyl methacrylate, ethyl methacrylate, butyl methacrylate, methacrylic acid-
Examples thereof include 2-ethylhexyl, lauryl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, and phenyl methacrylate. Examples of the acrylate monomer in the copolymer include ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, benzyl acrylate, and phenyl acrylate. Can be The methacrylic acid ester / acrylic acid ester copolymer may be obtained by further copolymerizing other monomer components. Examples of such a monomer include styrene, α-methylstyrene, and vinyl. Aromatic vinyl compounds such as toluene and chlorostyrene, acrylonitrile,
Examples thereof include vinyl cyanide compounds such as methacrylonitrile, vinyl esters such as vinyl acetate, dicarboxylic anhydrides such as maleic anhydride, and the like, but are not limited to these specific examples.

The resin composition of the present invention may contain, if necessary, an organic colorant, an inorganic colorant, a plate-out inhibitor, an antistatic agent, a heat resistance improver, a weather resistance stabilizer, and an adhesion improver. And various additives such as a plasticizer.

The calender molding of the resin composition of the present invention may be carried out according to a conventional method.
The resin composition that has undergone the kneading step is roll-formed into a sheet by a calendering machine to obtain a formed sheet. The temperature of the calender roll is preferably set in the range of 170 to 190 ° C.

[0027]

Next, specific embodiments of the present invention will be described.

<Materials used> Impact-resistant polystyrene resin
"H758K" (manufactured by Nippon Polystyrene Co., Ltd.) MBS copolymer ... "M-511" (manufactured by Kanegafuchi Chemical Co., Ltd.
MBS copolymer: "B-56" (manufactured by Kaneguchi Chemical Industry Co., Ltd., average particle size: 2,000 angstrom) MBS copolymer: "B-22" (manufactured by Kaneguchi Chemical Industry Co., Ltd., average particle size) MBA copolymer: "B-11A" (manufactured by Kaneka Chemical Co., Ltd.)
MBS copolymer: "B-51" (manufactured by Kaneka Chemical Co., Ltd., average particle size: 800 angstrom) Lubricant (metal soap): calcium stearate (manufactured by NOF CORPORATION, trade name "calcium stearate") S)) Lubricant: methyl methacrylate-alkyl acrylate-styrene copolymer (manufactured by Mitsubishi Rayon Co., Ltd., trade name "METABLEN P-700") <Example 1> Impact-resistant polystyrene resin (manufactured by Nippon Polystyrene Co., Ltd., product number " H758K ") 100 parts by weight, MBS
10 parts by weight of a copolymer (manufactured by Kanegafuchi Chemical Co., Ltd., product number "M-511", average particle size 2500 angstrom), and a methyl methacrylate-alkyl acrylate-styrene copolymer (manufactured by Mitsubishi Rayon Co., Ltd., "METABLEN" as a lubricant) P-7
00)) After kneading the resin composition obtained by mixing 1 part by weight with a Henschel mixer, a 0.4 mm-thick molded sheet (600 mm × 120 mm) was formed using an inverted L-type calender molding machine.
0 mm).

<Examples 2 to 6> A molded sheet was obtained in the same manner as in Example 1 except that the resin composition having the composition shown in Table 1 was used.

Comparative Example 1 M-511 (average particle size 250
A molded sheet was obtained in the same manner as in Example 2 except that B-11A (average particle diameter: 800 Å) was used instead of (0 Å).

Comparative Example 2 M-511 (average particle size 250
0 Å) and B-51 (average particle size 8).
A molded sheet was obtained in the same manner as in Example 2 except that the thickness was 100 Å.

Comparative Example 3 A molded sheet was obtained in the same manner as in Example 2 except that the amount of M-511 was changed to 5 parts by weight.

Comparative Example 4 A molded sheet was obtained in the same manner as in Example 2 except that the amount of M-511 was changed to 50 parts by weight.

Comparative Example 5 A molded sheet was obtained in the same manner as in Example 2 except that the blending amount of Metablen P-700 was changed to 0.2 part by weight.

Comparative Example 6 A molded sheet was obtained in the same manner as in Example 2 except that the blending amount of Metablen P-700 was changed to 12 parts by weight.

The performance of each molded sheet obtained as described above was evaluated by the following evaluation method. The results are shown in Tables 1 and 2.

<Sheet appearance evaluation method> The surface appearance of the obtained molded sheet was visually inspected, and a sheet having good surface appearance without any surface defects such as dents on the sheet surface was evaluated as "O".
The sheet having a dent on the sheet surface was marked "x".

<Izod Impact Strength Test Method> A plurality of formed sheets were laminated and integrated by a heating and press machine to make a thickness of 3 mm, and the Izod impact strength was measured in accordance with JIS 7110.

<Heat Deformation Temperature Test Method> A plurality of molded sheets were laminated and integrated by a heating and pressing press to a thickness of 3 mm.
The heat distortion temperature was measured according to ASTM D648.

[0040]

[Table 1]

[0041]

[Table 2]

As is clear from Table 1, the molded sheets obtained by calendering the resin composition for calendering of the present invention have good surface appearance with no occurrence of depressions or the like on the sheet surface. , Impact resistance and heat resistance.

On the other hand, the molded sheets of Comparative Examples 1 and 2, in which the average particle size of the graft copolymer fine particles deviated below the specified range of the present invention, were inferior in impact resistance. Also,
In the molded sheet of Comparative Example 3 in which the content of the graft copolymer fine particles deviated below the specified range of the present invention, depressions occurred on the sheet surface. Further, the molded sheet of Comparative Example 4 in which the content of the graft copolymer fine particles deviated beyond the specified range of the present invention was inferior in heat resistance. Further, in the molded sheet of Comparative Example 5 in which the content of the lubricant deviated below the specified range of the present invention, the molded sheet did not peel off from the calender roll, and the sheet could not be formed. In addition, the molded sheet of Comparative Example 6 in which the content of the lubricant deviated beyond the specified range of the present invention had a depression on the sheet surface.

[0044]

Since the resin composition for calendering of the present invention uses an impact-resistant polystyrene resin as the main resin, a calender molded article excellent in both impact resistance and heat resistance can be obtained. Further, since the lubricant is contained in a specific amount, the releasability from the calender roll is excellent. Furthermore, since the specific graft copolymer fine particles are blended in a specific amount, it is possible to effectively prevent the occurrence of depressions on the sheet surface during calendering without lowering the heat resistance. In addition, since the average particle size of the specific graft copolymer fine particles is specified to be 1200 angstroms or more, the above-described excellent effects (without deteriorating the excellent impact resistance of the impact-resistant polystyrene resin) can be obtained. (A depression prevention effect).

The average particle size of the graft copolymer fine particles is 15
When the thickness is in the range of 00 to 3000 angstroms, the occurrence of depressions on the sheet surface can be reliably prevented, and the surface quality can be further improved.

When the graft copolymer fine particles are methyl methacrylate-butadiene rubber-styrene copolymer fine particles, the occurrence of depressions on the sheet surface can be reliably prevented, and the surface quality can be further improved. .

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Claims (3)

[Claims] 1 to 100 parts by weight of an impact-resistant polystyrene resin, 0.5 to 10 parts by weight of a lubricant, and at least one compound selected from the group consisting of styrene compounds and alkyl (meth) acrylates. , A copolymer obtained by copolymerizing butadiene, or butadiene rubber as a core polymer, wherein the core polymer has a methacrylic acid alkyl ester having an alkyl group having 1 to 4 carbon atoms and an alkyl group having 1 carbon atom. A graft copolymer obtained by graft-polymerizing at least one monomer selected from the group consisting of alkyl acrylates, acrylonitrile and styrene-based compounds in one or more stages, having an average particle size of 1200 Å Characterized in that it contains 8 to 40 parts by weight of the fine particles of the graft copolymer described above. Over processing resin composition. 2. The graft copolymer fine particles have an average particle diameter of 1500 to 3000 Å.
The resin composition for calendering described in 1. 3. The calendering resin composition according to claim 1, wherein the graft copolymer fine particles are methyl methacrylate-butadiene rubber-styrene copolymer fine particles.