JPS5846209B2 - Thermoplastic resin extrusion foam and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an extruded thermoplastic foam having a closed cell structure and a method for producing the same. Moreover, the sheet-like one relates to an extruded thermoplastic resin foam having an extruded closed cell structure and having extremely excellent moldability.

BACKGROUND ART As an extruded thermoplastic resin foam having a closed cell structure, one made of polystyrene is known.

Such extruded polystyrene foam had non-uniform cells and a rough surface.

Furthermore, when sheet-shaped polystyrene extruded foam is molded to obtain molded products such as containers, the sheet is uniaxially stretched to a large extent during extrusion, resulting in sheet breakage and deep drawing. There was a drawback that it was difficult to obtain molded products.

When obtaining extruded polystyrene foam, the surface has poor slipperiness when extruded from a mold attached to the tip of the extruder.
It was difficult to take it to the roll during sizing molding.

Furthermore, since extruded polystyrene foam is generally flammable, organic halogen compounds are added to impart flame retardancy.

However, extruded foam containing organic halogen compounds
During processing and during product storage after foam molding, there are disadvantages in that undesirable phenomena such as foul odors caused by gases generated by the decomposition of organic halogen compounds, corrosion of molding equipment, and a significant decrease in weather resistance occur.

The inventors of the present invention conducted intensive research to solve the above-mentioned drawbacks, and as a result, they used a vinyl chloride polymer or a vinyl chloride copolymer as a core resin, absorbed a vinyl aromatic monomer into the core resin, and used the monomer as a core resin. By extrusion foaming using a thermoplastic resin containing a vinyl chloride car polymer or a vinyl chloride copolymer obtained by polymerizing it in a material resin,
The resulting extruded foam has excellent surface smoothness and bubble uniformity, and is slow to combust. They found that it was sufficient to add antimony, and therefore the weather resistance did not deteriorate, and that sheet-like products could be deep-drawn, and the present invention was completed.

That is, the present invention comprises 10 to 50 parts by weight of a vinyl chloride copolymer as a core resin, and a vinyl aromatic polymer obtained by absorbing a vinyl aromatic monomer into the core resin and polymerizing the monomer in the core resin. An extruded thermoplastic resin foam with a closed-cell structure consisting of a thermoplastic resin with 90 to 50 parts by weight of a combined resin, and a vinyl aromatic monomer added to a vinyl chloride polymer or a vinyl chloride copolymer as a core material resin. 10 to 50 parts by weight of a vinyl chloride polymer or vinyl chloride copolymer obtained by absorbing the monomer and polymerizing the monomer in the resin in the presence of a catalyst, and 90 to 90 parts by weight of a vinyl aromatic polymer.
50 parts by weight of a thermoplastic resin is fed to an extruder,
The gist of the present invention is a method for producing an extruded thermoplastic resin foam having a closed cell structure, which is characterized in that the extruded foam is kneaded with a foaming agent in the extruder and then extruded and foamed.

The extruded thermoplastic resin foam having a closed cell structure according to the present invention is produced by using a vinyl chloride polymer or a vinyl chloride copolymer as a core resin, and absorbing a vinyl aromatic monomer into the core resin. It is necessary that the material be made of a thermoplastic resin that is polymerized in the presence of a catalyst in a core resin.

A mixture is simply mixed with a vinyl aromatic polymer and a vinyl chloride polymer or a vinyl chloride copolymer, and this mixture is fed to an extruder and kneaded with a blowing agent to form, for example, a foamed sheet. The body lacks uniform mixing of both types, resulting in phase separation, fluffing on the surface, poor appearance, and a failure to increase the foaming ratio.

Furthermore, there are drawbacks such as the inability to obtain a desired deep drawn product.

The material made from the thermoplastic resin of the present invention does not have any of the drawbacks seen in the above-mentioned mixtures.

The thermoplastic resin used as a material in the present invention is
Vinyl chloride polymer or vinyl chloride copolymer 10-5
Vinyl aromatic polymer 90-50 made by absorbing a vinyl aromatic monomer into the core resin and polymerizing the monomer in the core resin in the presence of a catalyst.
It consists of parts by weight.

If the amount of vinyl chloride polymer or vinyl chloride copolymer contained in the thermoplastic resin is less than 10 parts by weight, the surface slipperiness during foaming and extrusion will not improve, and the air bubbles of the obtained extruded foam will not improve. It is not preferable because it is not uniform and lacks surface smoothness, and if it exceeds 50 parts by weight, it is not preferable because the moldability is actually hindered when it is formed into a sheet.

In the present invention, the core resin is not only a vinyl chloride homopolymer but also an ethylene-vinyl chloride copolymer, a vinyl chloride-styrene copolymer, a vinyl chloride-methyl meccrylate copolymer, and a vinyl chloride-methyl acrylate copolymer. , vinyl chloride-vinylidene chloride copolymer, vinyl chloride-diethyl maleate copolymer, vinyl chloride-vinyl acetate copolymer, and other vinyl chloride copolymers.

It is necessary that such a copolymer contains 50% or more of a vinyl chloride component.

Vinyl chloride polymer or vinyl chloride copolymer is spherical,
Particulate shapes such as pellets and flat shapes are suitable.

The size of such particles is preferably 0.5 to 5 g/t.

In the present invention, the vinyl aromatic monomers that can be absorbed into the core resin include styrene, α-methylstyrene, ethylstyrene, vinyltoluene, vinylxylene, isopropylxylene, etc. alone or in combination of two or more, and These vinyl aromatic monomers may be a mixture of monomers copolymerizable with vinyl aromatic monomers containing 50% by weight, such as acrylonitrile, methyl methacrylate, and the like.

In order to improve the impact resistance of the extruded thermoplastic resin foam having a closed cell structure according to the present invention, polyethylene, polypropylene, polybutene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, chlorinated polyethylene , chlorinated polypropylene, polybutadiene, acrylic ester resin, acrylonitrile-styrene copolymer, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene resin, methyl methacrylate resin, and the like.

In order to include such a resin in the extruded foam, it is necessary to include it in the core resin in advance, or to make the core resin absorb a vinyl aromatic monomer and then mix the above resin with a thermoplastic resin obtained by polymerization. After that, it can be incorporated by feeding it into an extruder and kneading it.

These resins may be used singly or in combination of two or more, but the amount used is 30% by weight or less.

If it exceeds 30% by weight, the moldability, rigidity, etc. of the resulting foam will deteriorate, which is not preferable.

An example of a method for obtaining the thermoplastic resin of the present invention is as follows.

A core resin made of vinyl chloride polymer or vinyl chloride copolymer is suspended in an aqueous medium containing a dispersant.

As a dispersant, in addition to organic compounds such as partially saponified polyvinyl alcohol, polyvinylpyrrolidone, and methylcellulose, one or more inorganic compounds consisting of fine powders that are poorly soluble in water such as calcium pyrophosphate and magnesium pyrophosphate are used in combination. 0.001-5 for water
Used in a wide range of weights.

A vinyl aromatic monomer is dropped into a suspension containing a core material resin.

The dropped vinyl aromatic monomer is absorbed by the core resin.

Since the rate of absorption is not fast, it is preferable to gradually drip the vinyl aromatic monomer used.

The absorbed vinyl aromatic monomer is polymerized in the presence of a catalyst in a core resin.

As such a catalyst, for example, organic peroxides such as benzoyl peroxide, tert-butyl peroxide, lauroyl peroxide, etc. are used.

This polymerization occurs at the decomposition temperature of the organic peroxide, i.e. 70-16
It is carried out at a temperature of 0°C.

When the polymerization is completed, a thermoplastic resin consisting of the vinyl chloride polymer or vinyl chloride copolymer and vinyl aromatic polymer of the present invention is obtained.

When, for example, an ethylene-vinyl chloride copolymer is used as the core resin, or when the core resin is previously impregnated with polyethylene, a partially graft-polymerized thermoplastic resin is obtained.

Further, when the thermoplastic resin contains a large amount of vinyl chloride polymer or vinyl chloride copolymer, a compatible vinyl aromatic polymer can be mixed with the thermoplastic resin in an extruder.

Thus, the method for producing an extruded thermoplastic resin foam having a closed cell structure according to the present invention will be specifically explained.

First, thermoplastic resin is supplied to the hopper of an extruder, and after being heated and melted and kneaded with a foaming agent in the extruder, it is released into the atmosphere from a die attached to the tip of the extruder in the form of a sheet, plate, rod, pipe, or Extruded as a profiled part.

The extruder is equipped with a rotating screw in a cylinder, and a single screw, a twin screw, etc. are used as appropriate.

Further, as the blowing agent kneaded into the thermoplastic resin, a volatile blowing agent or a thermally decomposable blowing agent is used.

Volatile blowing agents include n-pentane, i-pentane, n-pentane,
- Aliphatic hydrocarbons such as hexane, cycloaliphatic hydrocarbons such as cyclopenkune, cyclohexane, halogenated hydrocarbons such as methyl chloride, ethyl chloride, dichlorofluoromethane, chlorodifluoromethane, trichlorofluoromethane, methylene chloride, etc. are preferred. used for.

As decomposable blowing agents, azodicarbonamide, N, y
-dinitropentamethylene tetrane, 4°4'-oxybisbenzenesulfonyl hydrazide, etc. can be used.

The amount of these blowing agents used depends on the type of resin, the type of blowing agent,
Although it varies depending on the expansion ratio of the desired foam, it is generally used in an amount that is 2 or more by weight based on the total amount of resin in the composition to be foam-molded.

In addition, as stabilizers for improving the thermal stability of vinyl chloride polymers or vinyl chloride copolymers, tribasic lead sulfate, zinc stearate, zinc ricinol, calcium stearate, calcium laurate, tin stearate,
tin maleate, tin laurate, dibutyltin laurylate, zinc stearate, dibasic lead stearate,
One type or two or more types of lead naphthenate etc. can be added in combination.

It is preferable to use such a stabilizer in an amount of 0.05 to 6 weight more than the above polymer.

If the weight of the substrate is below 0.05 weight, the stability effect will be poor, and if the weight exceeds 6 weight φ, the physical properties will deteriorate.

Furthermore, nucleating agents such as talc, calcium carbonate, silica, perlite, ammonium carbonate, sodium bicarbonate, pigments, dyes, etc. may be mixed with the thermoplastic resin as appropriate before the resin is fed into the extruder.

In order to attach such additives to the surface of the resin, a spreading agent such as polybutene, liquid paraffin, polyethylene glycol, etc. is used.

In addition, since vinyl chloride polymer or vinyl chloride copolymer is used in this invention, small amounts of lubricants, antioxidants, plasticizers, fillers, etc. may be added as necessary in addition to the above-mentioned components. good.

The present invention is constructed as described above, and since the thermoplastic resin contains a vinyl chloride polymer or a vinyl chloride copolymer during extrusion foaming, it is caused by the good slipperiness between the goo and the foam. As a result, a good extruded foam with excellent surface smoothness can be obtained without causing problems such as roughness of the surface of the foam or difficulty in taking it to a roll.

In addition, the extruded foam of the present invention is slow-flaming (does not easily ignite when exposed to flame) and can be made flame retardant by simply adding antimony trioxide, which reduces its weather resistance. A sheet-like product without any molding has excellent secondary formability and can be deep-drawn.

Further, the extruded foam of the present invention has less dimensional change immediately after production and has a shorter aging period than polystyrene resin extruded foam.

Since the thermoplastic resin and extruded foam of the present invention have the above-mentioned advantages, they can be used in various applications requiring these properties.

In particular, it can be suitably used as a flame-retardant material whose demand has been increasing in recent years, such as interior materials, ceiling materials, and flooring materials for buildings; insulation materials for cold storage warehouses, heat insulation materials for greenhouses; foods, bottles, etc. 1 Used as containers for transporting machinery, machinery parts, etc.

Next, the present invention will be explained with reference to Examples.

In addition, in the following examples, all parts mean parts by weight.

Example 1 (a) Preparation of core material resin 86 parts of polyvinyl chloride resin (degree of polymerization 1030), 14 parts of antimony trioxide, and as stabilizers, 2 parts of tribasic lead sulfate and 1 part of lead stearate were mixed in a high-speed rotating mixer. The mixture was mixed using a 2-screw extruder and pelletized using a strand cut method.

The size of this pet is 2.3 mm in diameter and 2.0 mm in length.
It was mtn.

This pellet was used as a core resin.

(b) Manufacture of thermoplastic resin Magnesium pyrophosphate, a dispersant, is placed in the polymerization container.
．． 9 parts and 0 parts of sodium dodecylbenzenesulfonate
．． 200 parts of water in which 4 parts of 0.04 parts were dissolved was added, and 70 parts of the core resin prepared in section (a) was added thereto and dispersed.

The temperature of this was raised to 85°C, and a mixture of styrene monomer and polymerization catalyst was added thereto for 6 hours for polymerization.

The amounts added were 130 parts of styrene monomer, 0.35 parts of benzoyl peroxide and 0.15 parts of tert-butyl perbenzoate as polymerization catalysts.

Next, the temperature was raised to 110° C. and polymerization was continued for 2 hours to complete the polymerization, thereby obtaining a thermoplastic resin.

This thermoplastic resin consisted of 30 parts of polyvinyl chloride polymer, 65 parts of polystyrene polymer, and 5 parts of antimony trioxide.

(C) Extrusion foaming step (b) 0.1 part of polybutene as a spreading agent was added to 100 parts of the IJ thermoplastic resin and mixed in a tumbler, and further 0.5 part of talc was added and mixed.

This thermoplastic resin was supplied to an extruder having a diameter of 40 am.

Meanwhile, dichlorodifluoromethane (CCI□F2) was press-injected as a blowing agent from the middle of the extruder at a ratio of 7 parts to 100 parts of the thermoplastic resin.

The mold attached to the tip of the extruder was a 0.8 mm circular mold and was extruded into the atmosphere at a rate of 10 kg/Hr to foam, and a two-layer fused foam sheet with a width of 120 gm was obtained using the inflation method. .

This fused foam sheet has a thickness of 5mm and an apparent foaming ratio of 11.
．． The appearance was very smooth with an average cell diameter of 0.14 parts m.

When a combustion test was conducted in accordance with ASTM-1) 1692, it was found to be nonflammable.

Example 2 (a) Preparation of core material resin 96 parts of polyvinyl chloride resin (degree of polymerization 800), 4 parts of antimony dioxide, and 2 parts of tribasic lead sulfate and 2 parts of lead stearate as stabilizers were mixed in a high-speed rotating mixer. The mixture was mixed using a twin-screw extruder and pelletized using a strand cut method.

The size of this pellet is 2.211 mm in diameter. Length 2, O
It was mvi.

This pellet was used as a core resin.

(b) Manufacture of thermoplastic resin Magnesium pyrophosphate, a dispersant, is placed in the polymerization container.
．． 9 parts and 0 parts of sodium dodecylbenzenesulfonate
．． 200 parts of water in which 0.04 parts was dissolved was added, and 120 parts of the core resin prepared in section (a) was added thereto and dispersed.

This was heated to 85° C., and a mixture of styrene monomer and polymerization catalyst was added thereto for 5 hours for polymerization.

The amounts added were 80 parts of styrene monomer, 0.3 part of benzoyl peroxide as a polymerization catalyst, and 0.1 part of tert-butylhachenzoe f-1.

Next, the temperature was raised to 110° C. and polymerization was continued for 2 hours to complete the polymerization, thereby obtaining a thermoplastic resin.

This thermoplastic resin contains 57.6 parts of polyvinyl chloride polymer,
It consists of 40.0 parts of polystyrene polymer and 2.4 parts of antimony trioxide.

(C) Extrusion foaming step (b) 70 parts of the thermoplastic resin obtained in IIM and 30 parts of polystyrene resin (average degree of polymerization 1300) (40.3 parts of polyvinyl chloride resin component, 58.0 parts of polystyrene resin component, and It consists of 1.7 parts of antimony oxide)
was placed in a tumbler, 0.1 part of polybutene was added and mixed, and 0.5 part of talc was further added and mixed.

The thermoplastic resin obtained by mixing was supplied to the same extruder as in Example 1, dichlorodifluoromethane was press-fitted at a ratio of 7.5 parts to 10 parts of the resin, and the mixture was extruded into the atmosphere to foam. A two-layer wire-adhered foam sheet with a width of 120 mm was obtained using an inflation method.

This fused foam sheet has a thickness of 4.9cm and an apparent foaming ratio of 1.
0.5 times, average bubble diameter 0.16J! The appearance was very smooth.

The result of the combustion test was that it was non-flammable.

When this sheet was put through a vacuum forming machine, it loosened in the heating tank by the same amount in both the width (horizontal) direction and the flow (vertical) direction.

Therefore, when a deep molded product was molded using the plug assist method, the molded product was able to stretch well without cutting the sheet.

When a foamed polystyrene sheet is heated, it loosens well in the width direction, but it hardly loosens in the flow direction.

For this reason, when molded products such as deep or round products are heated and formed, the sheet may be cut or cracked in the flow direction.

With the sheet according to this example, the heated sheet loosens in the machine direction as well as in the width direction, making the above molding possible.

Comparative Example l 30 parts of polyvinyl chloride resin (degree of polymerization 1030), 65 parts of polystyrene resin powder (average degree of polymerization 1300), 5 parts of antimony trioxide, and 2 parts of tribasic lead sulfate as a stabilizer.
1 part lead stearate, 0.5 parts talc as a nucleating agent
parts were mixed using a high-speed rotating mixer.

This mixture was supplied to the same extruder as in Example 1, and dichlorodifluoromethane was press-injected as a blowing agent into the extruder at a rate of 8 parts per 100 parts of the mixture.

The mold attached to the tip of the extruder is a 0.8 mm circular mold for extrusion and foaming at a speed of 10 kg/Hr, and the inflation method is used to expand the foam to a width of 115 mm.
A layered foam sheet was obtained.

This fused foam sheet has a thickness of 4.3 plates and an apparent foaming ratio of 5.
The average cell diameter was 0.20 mm, the appearance was fluffy, and when the section sample was folded by hand, it broke easily, making it completely unusable.

Now, as modifiers for polyvinyl chloride resin, 10 parts of ABS resin, MBS resin, AS resin, and chlorinated polyethylene resin were added to 100 parts of polyvinyl chloride resin, and the same foaming and extrusion operation as above was performed. Similarly to the above, the foamed sheet was thin, had a low expansion ratio, was highly brittle, and had a poor appearance.

Reference Example 100 parts of polystyrene resin (average degree of polymerization 1300) was placed in a tumbler, 0.1 part of polybutene was added thereto and mixed thoroughly, and 1.0 part of Polyndef was added and mixed.

This mixture was supplied to the same extrusion apparatus as in Example 1, and dichlorodifluoromethane was press-injected as a blowing agent from the middle of the extruder at a ratio of 7 parts to 100 parts of the mixture.

The mold attached to the tip of the extruder has slits of 0 and 8 am.
The mixture was extruded and foamed using a circular mold at a rate of 10 kg/hr, and a two-layer line-adhesive foam sheet with a width of 120 mm was obtained using an inflation method.

This fused foam sheet has a thickness of 5xi and an apparent foaming ratio of 10.
．． 8 times, the average bubble diameter was 0.25 mm, and the appearance was rough with fine irregularities.

Example 3 (a) Creation of core resin 100 parts polyvinyl chloride resin (degree of polymerization 800) 3 parts tribasic lead sulfate 1 part each of stearic acid and calcium stearate Put the above resin and stabilizer in a high-speed rotating mixer. The mixture was mixed and fed into a twin-screw extruder to pelletize.

(b) Production of thermoplastic resin The core resin produced in section (a) was prepared using the method 1 shown in Example 1.
Polymerization was carried out to obtain thermoplastic resins having the proportions shown in the table.

(c) Extrusion foaming process Add 0.1 part of Porindef as a spreading agent to 100 parts of the thermoplastic resin in item (b), mix thoroughly in a tumbler, and further add 0.5 part of talc and mix. Ta.

This mixture was supplied to the same extrusion device as in Example 1, and butane was press-injected as a foaming agent at a ratio of 3.5 parts to 100 parts of thermoplastic resin, and the mixture was extruded into the atmosphere and foamed to a width of 115 mm using an inflation method. A two-layer lined foam sheet of ~120 mm was obtained.

This fused foam sheet was as shown in Table 1.

Comparative Example 2 The polyvinyl chloride resin pellets prepared in Example 3-a and polystyrene resin (average degree of polymerization 1300) were fed into a tumbler in the ratio shown in Table 2, and polybutene was added to 100 parts of the resin mixture. 0.1 part of talc was added and thoroughly mixed, and further 0.5 part of talc was added and thoroughly mixed.

This mixture was supplied to a foam extrusion apparatus in Example 3-(C'i section), and was extruded and foamed under the same operating conditions.

The results are shown in Table 2.

When the results shown in Example 3 and Comparative Example 2 are graphed in terms of apparent expansion ratio, the result is as shown in Figure 1, and as can be seen from this figure, the foamability of the thermoplastic resin according to the present invention is extremely excellent. .

Furthermore, it has features such as easy foam sheet thickness per unit amount of foaming agent and no fluffing appearance.

(In FIG. 1, curve a corresponds to Example 3, and curve S corresponds to Comparative Example 2.

) Example 4 The material resin of Example 3-(a) was used to impregnate and polymerize styrene monomer.

The composition of this thermoplastic resin is 70% polystyrene resin component.
1 part and 30 parts of a polyvinyl chloride resin component.

Adding polybutene and talc to this thermoplastic resin,
Mix thoroughly in a tumbler.

This thermoplastic resin was extruded using the same extrusion method as in Example 3 to obtain a two-layer line-adhesive foam sheet.

At this time, the amount of blowing agent (butane gas) is adjusted to
3.0, 3.5 and 4.5 parts, and the apparent foaming ratio of the sheet was determined.

The results are shown in FIG.

This foaming curve showed comparable behavior to polystyrene foam.

Comparative Example 3 Polybutene and talc were added to 30 parts of the pellets from Example 3-(a) and 70 parts of the polystyrene resin, and thoroughly mixed in a tumbler.

The amount of foaming agent was varied for this mixture as in Example 4, and the apparent foaming ratio was determined.

The results are shown in Figure 2.

As shown in FIG. 2, it can be seen that in Examples, a high foaming ratio can be obtained with a small amount of foaming agent.

(Curve C in FIG. 2 corresponds to Example 4, and curve d corresponds to Comparative Example 3.

) Example 5 (a) Preparation of core material resin Ethylene-vinyl chloride copolymer powder containing a large amount of ethylene (
86 parts of average polymerization degree (700), 14 parts of antimony trioxide, and 2 parts of tribasic lead sulfate and 1 part of lead stearate as stabilizers were mixed using a high-speed rotating mixer, and the mixture was fed to a twin-screw extruder to form strands. A core material resin was obtained by pelletizing using a cutting method.

The size of this core material resin is 2.1 ram in diameter and 2.1 ram in length.
It was 0 am.

(b) Production of thermoplastic resin As in Example 1, 130 parts of styrene monomer was absorbed into 70 parts of the core resin prepared in section (a) and polymerized in the particles.

The obtained thermoplastic resin contained 30 parts of ethylene-vinyl chloride polymer,
It consists of 65 parts of polystyrene polymer and 5 parts of antimony trioxide.

(c) Extrusion foaming step 100 parts of the thermoplastic resin of item (b) is added with 0.1 part of polybutene.
1 part and 0.5 part of talc were added and mixed.

This resin has a diameter of 4Qj! m, and dichlorodifluoromethane was press-injected as a blowing agent from the middle of the extruder at a ratio of 7 parts to 100 parts of resin.

The mold attached to the tip of the extruder has a slit of 0.65 mm.
The foam was extruded into the atmosphere at a rate of I Lkg/Hr using a circular mold, and a 110-part mold was attached to the tip of the mold.
It was blown up on a φ mandrel, taken up as a sheet with a width of 340 mm, and wound up into a roll.

The thickness of this sheet was 2.21L and 11L, the apparent foaming ratio was 11.5 times, and the cells were fine and uniform.

Furthermore, this sheet was flame retardant and could be heat-molded using a conventional secondary molding machine for foamed polystyrene sheets.

After heating at this time, the thickness was 5 mm in 4 parts. No cracks occurred in the molded product.

[Brief explanation of the drawing]

FIG. 1 shows an extruded thermoplastic resin foam according to the present invention (curve a in FIG. 1, see Example 3), and an extruded foam obtained by simply mechanically mixing a polyvinyl chloride resin and a polystyrene resin. (See curve b1 Comparative Example 2 in FIG. 1) is a graph showing the relationship between polyvinyl chloride resin content and apparent expansion ratio. Figure 2 shows the extruded thermoplastic resin foam according to the present invention (see curve C1 in Example 4 in Figure 2), as well as the extruded foam obtained by simply mechanically mixing polyvinyl chloride resin and polystyrene resin. 2 is a graph showing the relationship between the amount of foaming agent and the apparent foaming ratio for the foam (see curve d in FIG. 2, Comparative Example 3).

Claims (1)

[Scope of Claims] 1. 10 to 50 parts by weight of a vinyl chloride polymer or a vinyl chloride copolymer as a core material resin, and a vinyl aromatic monomer absorbed into the core material resin, and the seven polymers are added to the core material resin. An extruded thermoplastic resin foam having a closed-cell structure and made of a thermoplastic resin with 90 to 50 parts by weight of a vinyl aromatic polymer polymerized therein. 2 Vinyl chloride polymer or vinyl chloride copolymer obtained by absorbing a vinyl aromatic monomer into a vinyl chloride polymer or vinyl chloride copolymer that is a core material resin, and polymerizing the monomer in the resin in the presence of a catalyst. Polymer 10~
A thermoplastic resin consisting of 50 parts by weight and 90 to 50 parts by weight of a vinyl aromatic polymer is supplied to an extruder, kneaded with a foaming agent in the extruder, and then extruded and foamed. A method for producing an extruded thermoplastic resin foam having a closed cell structure.