JPH03109441A - Foam - Google Patents

Abstract

PURPOSE:To obtain a foam excellent in heat resistance, useful for packaging materials, thermal insulating materials, cushioning materials, etc., by expanding a resin composition containing e.g. a copolymer produced by copolymerization between an aromatic vinyl monomer and (meth)acrylic acid as the essential components. CONSTITUTION:The objective foam can be obtained by expanding a resin composition comprising (A) a copolymer produced by copolymerization between an aromatic vinyl monomer and (meth)acrylic acid as the essential components [pref. styrene-(meth)acrylic acid copolymer] and (B) a second copolymer produced by copolymerization between an aromatic vinyl monomer and a diene monomer as the essential components (pref. styrene-butadiene block copolymer or styrene-butadiene random copolymer).

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention maintains the heat resistance of a copolymer foam consisting of an aromatic vinyl monomer and (meth)acrylic acid as essential components, and is used as a packaging material for containers etc. The present invention relates to a foam that can be used as a heat insulating material, a cushioning material, etc. and has excellent secondary moldability.

<Prior Art> Polystyrene with or without rubber modification [hereinafter referred to as (rubber modified) polystyrene. ] has low specific gravity, tasteless, odorless, non-toxic, low hygroscopicity, excellent electrical insulation and high frequency insulation, good colorability and paintability, and good dimensional stability of molded products. In addition to these characteristics, it is used in large quantities in a wide variety of fields due to its excellent moldability and low cost. In particular, foams produced by various foaming methods are widely used in food packaging fields such as trays and containers; industrial fields such as insulation materials and cushioning materials; and distribution fields. However, it has drawbacks such as insufficient impact resistance, being immersed in oils and some solvents, insufficient heat resistance, easy flammability, insufficient weather resistance, and easy charging. There is. Among these drawbacks, the biggest one and the one that largely limits the range of use is its low heat resistance.

In recent years, with the rapid spread of microwave ovens, the method of cooking food in the microwave while it is still in a container is becoming more widespread.For these applications, foams based on (rubber-modified) polystyrene are heat-resistant. Currently, its use is limited due to its low value. In addition, in the field of insulation materials, (rubber-modified) polystyrene foams have high rigidity and are relatively easy to process in secondary molding. Although it is an optimal material for heat insulating materials for piping, its use in this field is largely limited due to its fatal flaw of low heat resistance.

As a method for improving the heat resistance of polystyrene foam, a foam made using a copolymer obtained by copolymerizing styrene with acrylic acid, methacrylic acid, or maleic anhydride (Japanese Unexamined Patent Publication No. 72830/1983) has been proposed. Although this method has been proposed, the technology for producing foam is limited, and there are many problems such as cracking, shrinkage, and deformation when the obtained foam is subjected to secondary molding into various containers etc. by vacuum forming etc. It was difficult to put it on an industrial mass production line.

On the other hand, as a means to utilize the heat resistance of styrene-methacrylic acid copolymer and to improve secondary molding processability, high-impact polystyrene (rubber-modified polystyrene) was added to styrene-methacrylic acid copolymer with 4 to 16 A laminated foam sheet (Japanese Unexamined Patent Publication No. 63-264335) has been proposed in which a foam sheet is manufactured using a resin composition which has been subjected to heavy gravity blending, and a styrene resin film is further laminated thereon.

<Problems to be Solved by the Invention> However, in this method, high-impact polystyrene is difficult to dissolve in the styrene-methacrylic acid copolymer, and its basic properties are limited to the heat resistance, strength, and
Not only does it have a negative effect on all secondary molding processability, but
It is extremely difficult to balance heat resistance, secondary molding processability, and surface condition of the foam, and there are also disadvantages in that reuse is severely restricted due to poor compatibility.

<Means for Solving the Problems> In view of the above facts, the present inventors conducted extensive research and found that a copolymer (A) obtained from an aromatic vinyl monomer and (meth)acrylic acid as essential components, and an aromatic It contains a copolymer (B) obtained as essential components of a group vinyl monomer and a diene monomer, more preferably (A) and (B).
) A resin composition also containing a resin (C) that is compatible with (
We discovered that the foam obtained by foaming 1) is easy to produce, has excellent heat resistance, appearance, and ease of secondary molding into containers, etc., and is also reusable. The invention was completed.

That is, the present invention provides aromatic vinyl monomers and (meth)
Contains a copolymer (A) obtained by copolymerizing with acrylic acid as an essential component, and a copolymer (B) obtained by copolymerizing and sweetening an aromatic vinyl monomer sene type monomer as an essential component. The object of the present invention is to provide a foam characterized by foaming the resin composition (I).

The copolymer (A) obtained by copolymerizing an aromatic vinyl monomer and (meth)acrylic acid as essential components used in the present invention is a copolymer of an aromatic vinyl monomer and acrylic acid and/or methacrylic acid. Original and/or terpolymer, and an aromatic vinyl monomer, acrylic acid and/or methacrylic acid, and other monomers copolymerizable with the aromatic vinyl monomer and/or (meth)acrylic acid. Examples include multi-component copolymers consisting of:

Examples of the aromatic vinyl monomer constituting the copolymer (A) include styrene, α-methylstyrene, p-methylstyrene, vinylxylene, monochlorostyrene,
Aromatic vinyl compounds such as dichlorostyrene, monobrom styrene, dibrom styrene, pt-butylstyrene, ethylstyrene, and vinylnaphthalene are mentioned, with styrene, α-methylstyrene, and pt-butylstyrene being preferred. Among these, styrene and a mixture of styrene and α-methylstyrene are preferred, and styrene is particularly preferred in consideration of economic efficiency.

Examples of (meth)acrylic acid include acrylic acid, methacrylic acid, or a mixture of acrylic acid and methacrylic acid, but among these, using methacrylic acid alone is the method for producing copolymer (A). This is preferred because it is easy to prepare and a foam with an excellent appearance can be obtained.

Aromatic vinyl monomer (a,) and (meth)acrylic acid (
The ratio (a, )/(a-) of a2) is usually 60/40 to 9
9/1, with a score of 7 in terms of the balance of polymer melt viscosity, appearance of molded products, heat resistance, rigidity, productivity, etc.
0/30~99/3 is preferable, 75/25~9515
is particularly preferred.

Other monomers copolymerizable with the aromatic vinyl monomer and/or (meth)acrylic acid include, for example, alkyl esters of (meth)acrylic acid such as methyl methacrylate, ethyl acrylate, butyl acrylate; acrylonitrile; Vinyl cyanide compounds represented by methacrylonitrile; polymerizable unsaturated fatty acids represented by itaconic acid, maleic acid, fumaric acid, crotonic acid, and cinnamic acid; N-methylmaleimide, N-ethylmaleimide, N-butylmaleimide, N-octylmaleimide, N-isopropylmaleimide, N-phenylmaleimide, N-p-7'romophenylmaleimide, N-o-
Maleimides typified by chlorphenylmaleimide, N-cyclhexylmaleimide, etc.; unsaturated carboxylic acid anhydrides typified by maleic anhydride, itaconic anhydride, citraconic anhydride, etc.; typified by allyl glycidyl ether, glycidyl methacrylate unsaturated compounds containing epoxy groups; unsaturated compounds containing amino groups represented by allylamine, aminoethyl methacrylate, aminopropyl methacrylate, and aminostyrene; acrylamide-based compounds represented by acrylamide and N-methylacrylamide ;2-hydroxyethyl-acrylate,
Examples include, but are not limited to, hydroxyl group-containing unsaturated compounds such as 3-hydroxypropyl methacrylate and 4-hydroxy-2-butene. The use of these other copolymerizable monomers is an effective means for further improving the effects of the present invention, such as heat resistance and compatibility. These other hexamers can be used alone or in combination of two or more. Further, these other monomers are usually used in an amount of 50 parts by weight or less based on 50 parts by weight of the aromatic vinyl monomer and (meth)acrylic acid. If the amount is 50 parts by weight or more, the properties of the copolymerizable monomer become noticeable, and the heat resistance of the copolymer (A) containing an aromatic monomer and (meth)acrylic acid as essential components may be reduced or the copolymer ( There is a large possibility that the compatibility of B) will be reduced, which is not preferable.

The copolymer (A) exemplified above can be produced by known and commonly used manufacturing methods, for example, JP-A-60-106818, JP-A-60
-168710, JP 61-43612, JP 61-163949, JP 62-74
It can be easily manufactured by the method exemplified in Japanese Patent No. 909 and the like. Specifically, emulsion polymerization, suspension polymerization, bulk polymerization, solution polymerization, or emulsion polymerization is carried out in the presence or absence of a known radical catalyst or ionic catalyst.
It can be produced by a known method such as suspension polymerization, emulsion-solution polymerization, suspension-solution polymerization method, or by a batch method, a continuous method, or a batch-continuous method.

For example, styrene monomer and methacrylic acid, and if necessary, other monomers that can be copolymerized with these, are added at a temperature of 60 to 180 C using a radical generator and a chain transfer agent.
1 Preferably, suspension polymerization or bulk polymerization is carried out at 75 to 120°C, and then additives such as antioxidants, plasticizers, flame retardants, and antistatic agents are added as necessary, and the process is carried out using an extruder, etc. It may be granulated by.

Although the polymer chain structure of the polymer produced by these production methods is not particularly limited, it is preferable that the aromatic vinyl monomer and (meth)acrylic acid are arranged randomly rather than arranged in a block structure. Preferred are random copolymers. The weight average molecular weight of the copolymer (A) is usually 30.000 to 500,000, and the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw)
/ (Mn) is usually preferably in the range of 2.0 to 10.0.

It goes without saying that the copolymer (A) thus obtained is itself an essential factor constituting the present invention. In addition, polymers in which some of the carboxyl groups present in the molecule have been pretreated to form acid anhydrides and/or modified polymers with glutaric anhydride groups, and alkali metals and alkaline earths that take advantage of the physical properties of carboxyl groups. Copolymers (A) also include polymers that are ionically crosslinked with similar metals, or modified polymers that are obtained by forming amide bonds and ester bonds with amino group-containing compounds, hydroxyl group-containing compounds, etc. .

On the other hand, the copolymer (B) obtained by copolymerizing an aromatic vinyl monomer and a diene monomer as essential components used in the present invention preferably uses butadiene as the diene monomer. Further, as the aromatic vinyl monomer used here, the same seven monomers as mentioned above can be used, and among them, styrene, α-methylstyrene, p-methylstyrene, etc. are preferable, and styrene is particularly preferable.

A particularly preferred copolymer (B) is styrene-
They are a butadiene block copolymer and a styrene-butadiene random copolymer. These can also be used in combination.

The copolymer (B) acts as an important factor in the ease of foam production and the appearance of the foam, which are the characteristics of the present invention, and is also a decisive factor in the secondary molding processability of the foam. In the case of a copolymer consisting only of butadiene and styrene, the content of butadiene is usually 20 to 90% by weight, and it is particularly easy to melt-knead and has good compatibility with copolymer (A) and processability for secondary molding. A range of 25 to 70% by weight is preferred in terms of superiority.

In the present invention, the usage ratio of copolymer (A) and copolymer (B) is usually 99.5/0.5-70/, taking into consideration heat resistance, secondary molding processability, and other points mentioned above. 30, preferably from 99.510.5 to 80/20, most preferably from 99/1 to 90/10.

The particle size (size of molecular aggregate) of the copolymer (B) in the resin composition (1) used in the present invention is determined by the ease of foam production, the appearance of the foam, and the secondary molding of the foam. From the viewpoint of excellent workability, the thickness is preferably 0.005 to 5.0 μm, and particularly preferably 0.01 to 3 μm.

When a polymer alloy, which is a blend of different polymers, is used as a base material as in the present invention, the compatibility between these polymers has an important influence on the properties of the foam. Generally, the physical properties of polymer alloys depend on the compatibility between the polymers, and in the case of incompatibility,
It also depends on the phase-separated structure and the affinity between the phase-separated phases.

For example, the higher the affinity of the interfacial phase, the better the mechanical strength. It is also known that in order to improve impact strength by blending rubber components, it is necessary that the rubber particle diameter be larger than a certain degree.

However, in the case of polymers, it is not easy to estimate the compatibility of polymer alloys and their physical properties. Conventionally, compatibility parameters have been used to estimate the compatibility of polymer alloys, and Flory Huggins' interaction parameters are also used.In addition, as a means of experimentally investigating compatibility, measurements of glass transition temperature using DSC etc., measurement of optical properties, observation with electron micrographs, light scattering or neutron scattering are used. Measurements of infrared absorption spectra using FTIR and the like have been conventionally performed.

A conventional method for improving the compatibility of polymer alloys and improving their physical properties is to blend homopolymers or graft, block or random copolymers into incompatible polymer alloys as so-called compatibilizers. is being carried out.

The function of the compatibilizer is to compatibilize the incompatible polymer alloy at the molecular level through the compatibilizer, and to improve the interfacial adhesion by improving the affinity during the 2 hours of phase separation. In the latter case, the effect of the surfactant is recognized, resulting in improved dispersibility of the rubber component, etc.

In the present invention, compatibility does not mean that two or more polymers are compatible at the molecular level, but also means that physical properties are improved by dispersing one polymer with good affinity in another polymer, such as copolymerization. A case where the copolymer (B) is dispersed with good affinity in the polymer (A) is also defined as being compatible in a broad sense.

From this point of view, the present inventors have solved the above (A) and (B).
It has also been found that it is useful to further contain a resin (C) which is compatible with these components in addition to these components.

Examples of the resin (C) that is compatible with components (A) and (B) selected from the above-mentioned viewpoint of compatibility include polyethylene,
Polypropylene, polyvinyl chloride, (rubber modified) polystyrene, As resin, ABS resin, polyvinyl alcohol, (meth)acrylic resin, vinylidene chloride resin,
AASAs resin BS resin, cellulose derivative resin, polyvinyl butyral, polymethylpentene-1, polybutene, polyisoprene, fluororesin, polyamide, polyacetal, polyester, polycarbonate, polyphenylene sulfide, polysulfone, polyether ether ketone, styrene/anhydrous Thermoplastic resins such as maleic acid copolymer resin, styrene/methyl methacrylate resin, (meth)acrylic acid modified polyethylene, polypropylene, polycaprolactone; or epoxy resin, phenoxy resin, phenol resin, urea resin, melamine resin, diaryl phthalate resin , silicone resin, unsaturated polyester resin, alkyd resin, urakyd resin, and other thermosetting resins. These resins can be used alone or in combination of two or more. Among these, preferable examples include polypropylene, polyvinyl chloride, (rubber-modified) polystyrene,
As resin, ABS resin, (meth)acrylic resin, polyisoprene, fluororesin, polyamide, polyacecool,
Polyester, polycarbonate, polyphenylene sulfide, polysulfone, polyether ether ketone, styrene/maleic anhydride copolymer resin, styrene/methyl methacrylate resin, (meth)acrylic acid modified polyethylene, polypropylene, polycaprolactone,
These include epoxy resin and phenoxy resin. Since these resins (C) are compatible with the components (A) and (B), they are useful even when used in combination with one of them.

The blending method can be one in which (A), (B), and (C) are carried out all at once, or one in which (A) or (B) is blended in advance and then combined with the others.

The amount of resin (C) used is (A) + (B) + (C)1
Usually 0 to 40% by weight, preferably 1% by weight based on 00 parts by weight
~25% by weight.

In the present invention, rubber components other than the copolymer (B) can be further contained within a range that does not significantly reduce heat resistance. Copolymer (A) and copolymer (B) have good compatibility, heat resistance, and other physical and chemical properties, but
In fields where impact resistance is required, further effects can be exhibited by further containing a rubber component.

The method of incorporating the rubber component is not particularly limited as long as the rubber component is contained in the composition in some form, but for example, the method of incorporating the rubber component into the copolymer (A) and the copolymer (B), rubber CD) and/or a method of mixing a rubber-containing thermoplastic resin (E) to form a polymer alloy. At this time,
Furthermore, resin (C) may be mixed.

The content of the rubber component is usually 0 to 40% by weight, preferably 0 to 10% by weight.

In the present invention, rubber (D) is a highly elastic polymeric material, in addition to the so-called rubber (D-1) defined by JIS, ASTM, etc., which does not require further vulcanization. It also includes thermoplastic elastomer (D-2), which is a polymeric material that exhibits plasticity in a high temperature range and rubber elasticity near room temperature.

Examples of the so-called rubber (D-1) in rubber CD) include natural rubber (NR), butadiene rubber (BR), imprene rubber (IR), chloroprene rubber (CR), butyl rubber, and ethylene-propylene rubber (EPDM, EPM). )
, acrylic rubber (ACM, ANM), chlorinated polyethylene rubber (C3R), fluororubber (FKM), silicone rubber (Q), urethane rubber (AU, EU), epichlorohydrin rubber, chlorosulfonated polyethylene, norbornene rubber, and/or Or their vulcanized polymeric materials are representative. Among these, butadiene rubber (BR), isoprene rubber (IR), chloroprene rubber, ethylene-propylene rubber (EPDM, EPM)
, acrylic rubber (ACM) is preferred.

Thermoplastic elastomer (D-2) is a polymeric material that does not require vulcanization and exhibits plasticity at high temperatures and rubber elasticity at room temperature, which is intermediate between rubber and thermoplastic resin or has characteristics of both. It is. These thermoplastic elastomers (D-2) have two mutually incompatible components: a soft segment that has elasticity in the polymer chain and a hard segment that is a crystalline or glassy component that prevents plastic deformation near room temperature. It has particular characteristics. Typical soft segments are amorphous polymers with low glass transition temperatures such as polybutadiene, polyether, and polyester, while hard segments are non-crosslinked hard segments such as polystyrene and polyurethane due to their constraint type and morphology. and crosslinked hard segments (ionomers) typified by alkali and alkaline earth metals. More specifically, it has a styrene-methyl methacrylate block or graft copolymer, butadiene and/or isoprene-styrene, methyl methacrylate, acrylonitrile block or graft copolymer and a hard segment and a soft segment as shown in the table below. Polymer materials are typical.

The rubber-containing thermoplastic resin (E) includes a blend resin obtained by mixing a thermoplastic resin with the above-mentioned rubber (D-1) and/or thermoplastic elastomer (D-2), a polymerizable monomer, and a polymerizable monomer copolymerizable with them. Examples include copolymer resins obtained by copolymerizing the above rubber (D-1) and/or thermoplastic elastomer (D-2). Examples of polymerizable monomers used here include aromatic vinyl monomers such as styrene, α-methylstyrene, and -butylstyrene; unsaturated fatty acids such as acrylic acid, methacrylic acid, and maleic anhydride; methyl unsaturated fatty acids; Alkyl esters such as , ethyl, butyl; acrylonitrile, methacrylonitrile, phenyl or cyclohexyl maleimide, and the like.

These monomers may be used alone or in combination.

Among these, diene rubbers such as polybutadiene and polyisoprene, styrene, (meth)acrylic acid, methyl (
A copolymer resin prepared by copolymerizing one or more monomers selected from meth)acrylate, maleic anhydride, and acrylonitrile is preferred.

Furthermore, a copolymer resin obtained by graft or block copolymerization is preferable, such as a copolymer resin obtained by graft copolymerizing styrene and/or methyl methacrylate onto polybutadiene (MBS resin), in the presence of polybutadiene. Rubber-modified polystyrene (so-called high-impact polystyrene) made by polymerizing styrene with polystyrene, copolymer resin (ABS resin) made by copolymerizing styrene and acrylonitrile with polybutadiene, and styrene and/or EPDM.
Alternatively, a copolymer resin obtained by copolymerizing acrylonitrile may be used.

The rubber component contained in the rubber-containing thermoplastic resin (E) is usually in the range of 5 to 90% by weight, preferably 40 to 70% by weight. These rubber components may be used alone or in combination.

(A) and (B) above, and (C) to (E) as necessary.
The resin composition (I) containing component (I) can be produced by a known and commonly used method. That is, a method of mixing using a heating roll, a Banbury Mixer-1 single screw extruder, a twin screw extruder, a single screw-biaxial wire bonded extruder, or (A)
It can be produced by simply triblending the components (E) to (E).

The resin composition (1) thus obtained further contains commonly used compounding agents such as a nucleating agent, a foaming aid, an antioxidant, an ultraviolet absorber, a lubricant, a flame retardant, and an antistatic agent. can do.

Among these compounding agents, preferable compounding agents include saturated fatty acids and/or their esters described in JP-A-58-96641; hydroxyl group compound 1 described in JP-A-59-230043; and hydroxyl compound 1 described in JP-A-60-181157. Organic polysiloxanes described in JP-A-61-19648; mineral oils as described in JP-A-61-19647; polyester plasticizers, hindered amine antioxidants, triphenyl phosphate, tri(nonylphenyl) as described in JP-A-61-21147; Phosphates and their oligomers, polymer-type phosphorus flame retardants; and other flame retardants listed in "Flame Retardant of Polymers" published by Taiseisha (February 1988); Tetrabromobisphenol A/epichlorohydrin co-condensation Flame retardants such as polymeric polymers are preferred.

In addition to these, fillings such as glass fiber, carbon fiber, metal fiber, glass peas, glass powder, glass flakes, asbestos, unilastonite, mica, talc, clay, calcium carbonate, titanium, calcium titanate, barium sulfate, etc. These agents can be used alone or in combination. These fillers are used in a resin composition (1) consisting of (A) and (B) and, if necessary, (C) to (E).
The content is preferably 1 to 150 parts by weight.

The foam of the present invention is made from the resin composition (I) obtained above.
) can be obtained by a known and commonly used method. For example, after putting the resin composition (I) into an extruder and heating and melt-kneading it, a low boiling point halogenated hydrocarbon such as dichlorodifluoromethane; a low boiling point hydrocarbon such as propane or butane;
Carbon dioxide gas: After pressurizing a so-called foaming agent such as a compound that decomposes at high temperature and generates gas such as soda carbonate, it is cooled to the appropriate temperature for foaming, and then extruded through a circular die or T-die, etc., and easily foamed. can get.

If the foam is sheet-like or plate-like, the thickness is 0.5
A+m~200II11 is suitable. The thickness is 0.5
If it is less than 1, the strength, heat insulation, and heat resistance of the molded product will not be sufficient, and deep drawing molding such as a "donburi" mold will be particularly difficult. In addition, the density of the foam is 0.02 to 0.5 g/
c113 is suitable. When the density exceeds 0.5 g/cra3, the foam becomes hard and problems such as cracking are likely to occur when the foam is formed into a sheet and rolled up. On the other hand, if the density is less than 0.02 g/cm', heat resistance and strength decrease, which is not preferable.

The foam in the present invention can be used alone for various food packaging materials,
It is useful for industrial parts, materials, and distribution materials, but can also be used to laminate other films on one or both sides. The film is selected based on criteria such as the purpose of use and whether or not it can be reused, but copolymer (A) and/or copolymer (B)
A film having a thickness of 10 to 300 ays selected from resins compatible with the above is preferred. From this point of view, as base materials for films, styrene-methacrylic acid copolymer, polymethyl methacrylate, styrene-methyl methacrylate copolymer, styrene-maleic anhydride copolymer, polycarbonate, polyphenylene ether, etc.
One type of resin (C) or a mixture of two or more types of resin (C) that is compatible with the components (A) and (B), and the resin (C) is combined with a rubber component (D) and/or a rubber-containing thermoplastic resin ( A combination of E) is preferred. These films are produced by non-stretching, -axial stretching, biaxial stretching, or other methods, and then, if necessary, after printing, they are attached to one or both sides of the foam of the present invention through an adhesive or by direct heat bonding. By doing so, it is possible to improve the aesthetic strength and heat resistance of the pipe.

When the foam of the present invention is relatively thick, it is suitable for insulation and cushioning materials such as boards, and when it is relatively thin, it is suitable for various food packaging materials and food containers such as cups, trays, bowls, and shrink labels. It is useful as Especially the thickness is 1m
Foams or laminated foams with a size of about 5 mm to 5 mm are useful as foams that can be fully used in vacuum and/or pressure molding processes, and have excellent heat resistance, so they can be heated and cooked in a microwave oven.

<Example> Next, the present invention will be explained in more detail with reference examples, examples, and comparative examples, but the present invention is not limited thereto.

Note that parts and percentages are based on weight unless otherwise specified. In addition, various physical properties were determined by the following methods.

Physical property measurement method 1-1 (heat distortion temperature) ^High load (18.6 kg/cm) according to STMD-648
It was calculated under the following conditions.

1-2 (Average Molecular Weight) M W / M n was measured by dissolving a sample in tetrahydrofuran using gel permeation chromatography manufactured by Shimadzu Corporation.

1-3 [Particle diameter of copolymer (B) (size of molecular aggregate)] The resin composition (1) obtained by melting and kneading each component was dyed with osminium tetroxide, and ultrathin pieces were obtained. Create one and take an electron micrograph. Measure the diameter of the disperser magnified in the photograph. As the first particle diameter Di, number average particle diameter = Σn1Di/
It is expressed as Σni. However, if the average value cannot be measured,
Written in range.

1-4 (Difficulty in producing foam) Components (A) and (B), and if necessary, (C), (
Components D) and (E) were blended in the proportions shown in Table 1, and a resin composition (I) obtained by blending 0.3 parts by weight of talc as a nucleating agent was put into a 50 mmφ extruder. After melt-kneading, add 3 to 4 parts of dichlorodifluoromethane or butane as a blowing agent to 100 parts by weight of the resin composition (1).
It was press-fitted in a proportion equal to parts by weight. After that 65III
Transfer to a φ extruder, cool, and extrude through a circular die to foam to produce a foam sheet with a thickness of 2.01aIa to 5.0 mm and a density of 0.08 to 0.11 g/cm3,
The manufacturability of the foam was evaluated using the following criteria.

Judgment criteria ◎: No cracking of the winding receipt, no rise in molding temperature and pressure.

O: No cracking of the sheet during winding.

Δ: The winding receipt cracks. Can be rolled up.

×: The sheet was cracked during winding, and winding was not possible.

1-5 (Secondary molding processability) After the foamed sheet obtained in the above physical property measurement method 1-4 was left at room temperature for 7 days, it was molded with an inner diameter of 170+mφ and a depth of 60+nm using a single-shot vacuum forming machine for forming styrene foam sheets. A flaky container was formed, and the shape and appearance of the container were evaluated according to the following criteria.

Judgment criteria ◎: A shape matching that of two metals was obtained and the appearance was excellent.

◯: A molded product conforming to the shape of two metals is obtained. There are no defective parts on the surface of the molded product.

Δ: The bottom unevenness and corners of the two-metal metal do not match the mold shape. There are small cracks on the surface of the molded product.

The shape is far from the ×8 mold shape, and dimensions such as depth are not shown. There are many cracks on the surface of the molded product.

1-6 (Secondary forming process life) The secondary processability was evaluated in the same manner as in 1-5 above, except that the period of time the foamed sheet was allowed to stand was changed to 60 days.

1-7 (Appearance of foam) After visually determining the gloss of the foam sheet obtained in physical property measurement method 1-4, cut it with a sharp knife, etc., and examine the cut surface with a magnifying glass (50x magnification). The degree of unevenness on the sheet surface was determined using the following criteria.

Judgment Criteria ◎: The unevenness of the sheet surface is less than 0.05 mm, and the gloss is good.

O: The unevenness on the sheet surface is less than 0.05 mm, but the gloss is slightly inferior.

Δ: There is unevenness of 0.05 to 0.1 mm on the sheet surface,
The gloss is also inferior.

×: There are irregularities larger than 0.1 mm on the sheet surface, and the gloss is poor.

1-8 (Heat resistance) Pour 200 g of water into the flaky container obtained in Physical property measurement method 1-5, heat it in a microwave oven for 150 seconds, and then check for deterioration such as changes in the shape of the container according to the following criteria. I judged it.

Judgment criteria ◎: No dimensional change, external appearance change, or deterioration observed.

○: There is some dimensional change.

Δ: There is some dimensional change and some swelling due to secondary foaming.

×: Significant change in appearance due to secondary foaming.

■-8 (Reusability) After shredding the flaky containers and scraps such as paris obtained in Physical Property Measurement Method 1-5 using a crusher, using a vented extruder,
Melting, defoaming, and pelletization were performed at an extrusion temperature of 250°C. These pellets were added to the resin compositions (I) used in Examples 1 to 15 and Comparative Examples 1 to 6 at 30% by weight, respectively.
A foamed sheet was produced under the same conditions except for mixing, and was evaluated using the following criteria.

Judgment Criteria ◎: There was no significant change in the appearance or manufacturing conditions of the foam sheet.

O: There were slight changes in the appearance and manufacturing conditions of the foam sheet.

Δ: There was a change in the appearance and manufacturing conditions of the foam sheet. ×: There was a significant change in the appearance and manufacturing conditions of the foam sheet.

Reference example 1 5I equipped with turbine-type stirring blades! A stainless steel reactor was charged with 2.00 On + β of distilled water, and after dissolving 10 g of partially ketonized polyvinyl alcohol and 0.05 g of sodium dodecylbenzenesulfonate as a suspension stabilizer, 940 g of styrene, 60 g of methacrylic acid, 10 g of liquid paraffin, and peroxy 4 g of di-tert-butyl hexahydroterephthalate and 1 g of tert-butyl perbenzoate were charged sequentially. After purging the inside of the vessel with nitrogen gas, the temperature was raised under stirring at 500 rpm, suspension polymerization was carried out at 90°C for 10 hours, and further 1
The reaction was carried out at 20°C for 3 hours. The resulting particulate styrene-methacrylic acid copolymer was washed, dehydrated, and dried.

Next, 0.5% stearyl alcohol was added to the copolymer, and the mixture was pelletized in a nitrogen stream using an extruder with a cylinder temperature of 260°C. Hereinafter, this will be abbreviated as copolymer (A-1).

Reference Example 2 Reference Example 1 except that each monomer was used in the composition shown in Table 1.
Copolymers (A-2) to (A-5) were obtained in the same manner as above.

However, in (A-4) and (A-5), 1% mineral oil was added.

Examples 1 to 15 and Comparative Examples 1 to 6 After mixing each resin component shown in Table 1 in a tumbler,
Using a 40 mmφ twin-screw extruder, the mixture was melted, kneaded, and pelletized at 200 to 250°C. 100 parts of the obtained pellets and 70.3 parts of talc were placed in a 50Ill tube connected with a single tube.
IIIφ and 65mmφ tandem extruder, put it into the first stage 50mmφ extruder and raise the temperature to 200 to 250°.
While melt-kneading with C, add dichlorodifluoromethane or
- Butane is press-injected, then transferred to the second stage 65 mmφ extruder, and after cooling to 130-150°C, the 65 mm
It is foamed while being extruded into a cylindrical shape from a circular die attached to an mφ extruder, with a thickness of 2 to 5 mm and a density of 0.
A foam with a weight of 0.08 to 0.106 g/cm' was obtained and its physical properties were measured. The results are shown in Table-2.

/ *1) (B-1): Styrene-butadiene block copolymer, Asaflex 810 manufactured by Asahi Kasei Corporation, butadiene content 32%.

*2) (B-2): Styrene-butadiene random copolymer, HSR-0051 manufactured by Nihon Gosei Rubber Co., Ltd., butadiene content 42%.

*3) (B-3): Styrene-butadiene block copolymer, one resin manufactured by Phillips Chemical Co., butadiene content 29%.

*4) (B-4): Styrene-butadiene methyl methacrylate copolymer, Kaneate B-56 manufactured by Kanebuchi Chemical Co., Ltd., butadiene content 70%*5)
(C-1): Styrene-methyl methacrylate copolymer, manufactured by Nippon Steel Chemical ■.

*6) (C-2): Polystyrene (homopolymer).

*7) (C-3): polymethyl methacrylate,
Barapet EH manufactured by Kyowa Gas Chemical Industry ■.

*8) (C-4): Polyphenylene ether resin, manufactured by Aldrich, USA.

*9) (C-5): Polycarbonate resin, Tubarex manufactured by Mitsubishi Chemical Corporation.

*10) (D-1)”: ethylene-propylene-
Diene copolymer, EP-912-P manufactured by Nihon Gosei Rubber.

*11) (D-2): Polyurethane elastomer, Pandex T-2190° manufactured by Dainippon Ink & Chemicals *12) (E-1): High impact polystyrene, butadiene content 8%.

(Effects of the Invention) The foam of the present invention has advantages in that it is easy to manufacture, has excellent heat resistance, appearance, and processability for secondary molding, and can be reused.

Claims (1)

[Claims] 1. A copolymer (A) obtained by copolymerizing an aromatic vinyl monomer and (meth)acrylic acid as essential components, and an aromatic vinyl monomer and a diene monomer as essential components. A foamed product obtained by foaming a resin composition (I) containing a copolymer (B) obtained by copolymerization. 2. The foam according to claim 1, wherein the copolymer (B) is a styrene-butadiene block copolymer and/or a styrene-butadiene random copolymer. 3. The foam according to claim 2, wherein the copolymer (A) is a styrene-(meth)acrylic acid copolymer. 4. The foam according to claim 1 or 3, further comprising a resin (C) that is compatible with the copolymer (A) and the copolymer (B). 5. The foam according to claim 2 or 3, wherein the copolymer (B) has a butadiene content of 25 to 70% by weight.