JPH05117436A - Production of vinyl chloride resin foam - Google Patents

Abstract

PURPOSE:To produce a cross-linked vinyl chloride resin foam excellent in physical properties at a high expansion ratio under normal pressure without using any cross-linker. CONSTITUTION:An epoxidized vinyl chloride resin having an epoxy group content at the surface of the resin particles of 1X10<-2>wt.% or higher, a total epoxy group content of 10wt.% or lower, and a mean particle diameter of 0.05-5mum is mixed with an org. blowing agent having a decomposition temp. of 100 deg.C or higher and a plasticizer below the decomposition temp. of the blowing agent and foamed by heating to give the title foam.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for producing a vinyl chloride resin foam. More specifically, the present invention relates to a method for efficiently producing a polyvinyl chloride foam having a high expansion ratio under normal pressure.

[0002]

2. Description of the Related Art Plastic foams made of various materials have been put into practical use, but polyvinyl chloride resins have advantages such as excellent weather resistance, free coloring, and various shape-imparting properties. Despite having
Since it is difficult to obtain a high-magnification foam, the demand is not so large compared to polyurethane and polyolefin. Hitherto, a method for producing a high-magnification foam using a vinyl chloride resin has been carried out by introducing an inert gas under high pressure or decomposing a foaming agent. However, in such a method, there is a drawback in that a facility that can withstand high pressure is required, and since the method is a batch method, the productivity is poor and the cost is inevitably high. On the other hand, in the normal-pressure foaming method, the decomposition viscosity of the vinyl chloride resin is low at the decomposition temperature of the ordinary foaming agent or higher and the decomposed gas is easily released, and when a low-temperature foaming agent is used, the melting of the resin is insufficient. However, since the decomposed gas is likely to be dissipated, a high-magnification foam cannot be obtained. As a method for obtaining a high-magnification vinyl chloride resin foam at normal pressure, for example, a method for producing a high-magnification foam by decomposing the foaming agent by heating after crosslinking vinyl chloride-ethylene copolymer resin by irradiation with radiation. Has been proposed (Japanese Patent Publication No. 48-4863).
However, this method has the drawbacks that the radiation irradiation equipment is expensive, the cost of the foam is high, and the vinyl chloride resin is easily deteriorated and discolored by radiation. Further, a vinyl chloride resin plastisol comprising a copolymer resin of vinyl chloride and a monomer containing a hydroxyl group, a carboxyl group, an epoxy group or an alkoxy group, a plasticizer, a crosslinking agent and a foaming agent is used for crosslinking and foaming. Accordingly, a method for producing a vinyl chloride resin foam having good cushioning properties, weather resistance and flame retardancy and a high expansion ratio is disclosed (Japanese Patent Publication No. 52-44588). However, in this method, since a cross-linking agent is used, cross-linking gradually progresses at room temperature, and as a result, the viscosity of plastisol with time increases, so that there is a drawback that the storage stability of plastisol is poor, and as a cross-linking agent, Since the acid used tends to inhibit foaming, it is not possible to obtain foaming at a high magnification as expected, and the unreacted cross-linking agent bleeds onto the foam surface to make it easy to stain or when printing on the surface. It causes an unfavorable situation such as ink peeling.

[0003]

Under the above circumstances, the present invention provides a crosslinked foam of a vinyl chloride resin having a high expansion ratio and excellent physical properties under normal pressure without using a crosslinking agent. It was made for the purpose of obtaining.

[0004]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that a vinyl chloride resin having a specific epoxy group content and an organic resin having a specific foaming decomposition temperature. It was found that the object can be achieved by kneading a foaming agent and a plasticizer at a temperature at which the foaming agent does not decompose, and then heat-foaming and molding, and the present invention has been completed based on this finding.

That is, the present invention contains an epoxy group having an epoxy group concentration of 1 × 10 ^-2 % by weight or more and a total epoxy group concentration of 10% by weight or less and an average particle size of 0.05 to 5 μm. A vinyl chloride resin characterized by kneading a vinyl chloride resin with an organic foaming agent having a foaming decomposition temperature of 100 ° C. or higher and a plasticizer at a temperature at which the foaming agent does not decompose and then heat-foaming and molding. A method for producing a foam is provided.

The present invention will be described in detail below. The epoxy group-containing vinyl chloride resin used in the method of the present invention comprises (1) a vinyl chloride unit, a monomer unit having an epoxy group, and a monomer unit optionally introduced and copolymerizable with these units. Copolymers, and (2) those obtained by adding an epoxy group to a polymer mainly composed of a vinyl chloride unit and a monomer unit copolymerizable with vinyl chloride, which is optionally introduced.

The copolymerizable monomer unit optionally introduced into the epoxy group-containing vinyl chloride resin is
For example, vinyl acetate, fatty acid vinyls such as vinyl propionate, ethylene, olefins such as propylene, vinylidene chloride, vinylidene halides such as vinylidene fluoride, isobutyl vinyl ether, methyl vinyl ether, vinyl ethers such as ethyl vinyl ether, allyl chloride, Examples thereof include monomer units such as allyl compounds such as methylallyl ether, and these may be introduced in one kind or in two or more kinds.
It is desirable that the monomer units of these desired components are introduced into the epoxy group-containing vinyl chloride resin at a ratio of 10% by weight or less.

Examples of the epoxy group-containing monomer used in (1) the epoxy group-containing vinyl chloride resin include glycidyl ethers of unsaturated alcohols such as allyl glycidyl ether and methallyl glycidyl ether, glycidyl methacrylate, Glycidyl esters of unsaturated acids such as glycidyl acrylate, glycidyl-p-vinyl benzoate, methyl glycidyl itaconate, glycidyl ethyl maleate, glycidyl vinyl sulfonate, glycidyl (meth) allyl sulfonate, butadiene monooxide, vinyl cyclohexene monoxide, 2 Examples include epoxide olefins such as -methyl-5,6-epoxyhexene.
These epoxy group-containing monomers may be used alone or in combination of two or more. On the other hand, as a method of adding an epoxy group in the epoxy group-containing vinyl chloride resin of the above (2), after dehydrochlorination of the vinyl chloride resin by heat treatment or contact with an alkali compound,
A method of epoxidizing with an organic peracid or the like can be used.

In the present invention, the epoxy group-containing vinyl chloride resin has an epoxy group concentration on the surface of the resin particles of 1 × 10 ⁻² wt% or more, preferably 5 × 10 5.
It is necessary that the concentration is ^{−2 to} 5 × 10 ⁻¹ % by weight, and the concentration of epoxy groups in the entire resin particles is 10% by weight or less, preferably 0.5 to 5% by weight. If the concentration of epoxy groups on the surface of the resin particles is less than 1 × 10 ^-2 % by weight, the crosslinkability is poor, and if the concentration of total epoxy groups exceeds 10% by weight, the viscosity of plastisol becomes high, which is not preferable. The surface epoxy group concentration and total epoxy group concentration are
It can be measured by the method described below. Further, it is particularly preferable that the epoxy group-containing vinyl chloride resin has a higher epoxy group concentration in the outer shell portion of the particle than the epoxy group concentration in the inner core portion of the particle. When the epoxy group concentration on the particle surface satisfies the requirements of the present invention, and the polymerization is carried out so that the epoxy group concentration in the entire particle becomes uniform, the epoxy group-containing monomer unit is in a large amount, so that the polymer particle of the plasticizer is Swelling becomes prominent, and the particle size of plastisol and the increase in viscosity over time tend to increase.

In the present invention, the epoxy group-containing vinyl chloride resin is required to have an average particle size of 0.05 to 5 μm, preferably 0.5 to 5 μm. If the average particle size of the resin particles is in the above range, the fluidity of the plastisol will be high, but if it is out of this range, the viscosity of the plastisol will be high and the handleability will be poor. The epoxy group-containing vinyl chloride resin used in the method of the present invention preferably has an average degree of polymerization in the range of 600 to 3000. If the average degree of polymerization is less than 600, the mechanical strength is not sufficient and exceeds 3000. In addition, a large amount of heat is required in the foaming process, and the melt viscosity tends to be too high, resulting in poor foaming.

The epoxy group-containing vinyl chloride resin used in the method of the present invention can be produced by, for example, an emulsion polymerization method or a micro suspension polymerization method suitable for producing a vinyl chloride resin for paste processing. By these production methods, a latex in which resin particles having an average particle size of 0.05 to 5 μm are uniformly dispersed can be obtained. As a preferred production condition, in order to obtain the epoxy group-containing vinyl chloride resin of the present invention having a high content of the epoxy group in the outer shell portion including the particle surface, the monomer having an epoxy group is added in the latter half of the polymerization reaction. The content of epoxy groups in the polymer forming the outer shell of the polymer is increased by either charging the charge or gradually increasing the charge rate during the polymerization reaction. As is well known, a polymer of vinyl chloride does not dissolve in a monomer (vinyl chloride), and a polymer generated by a polymerization reaction precipitates in a monomer solution. Therefore, when the monomer having an epoxy group is charged in the latter half of the polymerization reaction, the particles of the polymer having the polymer having a large amount of the epoxy group as the outer shell and the aggregate thereof are subjected to the suspension polymerization or the bulk polymerization. You can get it. This structure is particularly remarkable in the microsuspension polymerization in which the monomer droplets are within 1 μm. Further, in emulsion polymerization, the place of the polymerization reaction during the polymerization is the surface of the polymer that is always in contact with water, so that the epoxy group-containing concentration of the outer shell part can be adjusted by charging the monomer having an epoxy group in the latter half of the polymerization reaction. The epoxy group-containing vinyl chloride resin of the present invention having a higher epoxy group-containing concentration in the inner core can be obtained.

In the method of the present invention, the plasticizer blended in the epoxy group-containing vinyl chloride resin is not particularly limited, and those conventionally used as plasticizers for vinyl chloride resin can be used. Examples of such compounds include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, di- (2-ethylhexyl)
Phthalate, di-n-octyl phthalate, diisobutyl phthalate, diheptyl phthalate, diphenyl phthalate, diisodecyl phthalate, ditridecyl phthalate, diundecyl phthalate, di (heptyl, nonyl, undecyl) phthalate, benzyl phthalate, butyl benzyl phthalate, dinonyl phthalate. , Phthalic acid derivatives such as dicyclohexyl phthalate, dimethyl isophthalate, di- (2-ethylhexyl) isophthalate, isophthalic acid derivatives such as diisooctyl isophthalate, di- (2-ethylhexyl) tetrahydrophthalate, di-n-octyl tetrahydro Phthalates, tetrahydrophthalic acid derivatives such as diisodecyl tetrahydrophthalate, di-n-butyl adipate, di- (2-ethylhexyl) Adipic acid derivatives such as dipate, diisodecyl adipate and diisononyl adipate, azelaic acid derivatives such as di- (2-ethylhexyl) azelate, diisooctyl azelate, di-n-hexyl azelate, di-n-butyl sebacate, di- ( 2-ethylhexyl) sebacate and other sebacic acid derivatives, di-n-butyl maleate, dimethyl maleate,
Maleic acid derivatives such as diethyl maleate and di- (2-ethylhexyl) malate, fumaric acid derivatives such as di-n-butyl fumarate and di- (2-ethylhexyl) fumarate, tri- (2-ethylhexyl) trimellitate, trimerate Trimellitic acid derivatives such as -n-octyl trimellitate, triisodecyl trimellitate, triisooctyl trimellitate, tri-n-hexyl trimellitate, triisononyl trimellitate, tetra- (2-ethylhexyl) ) Pyromellitate, tetra-n
-Pyromellitic acid derivatives such as octylpyromellitate, triethyl citrate, tri-n-butyl citrate, acetyl triethyl citrate, acetyl tri-
(2-Ethylhexyl) citrate and other citric acid derivatives, monomethyl itaconate, monobutyl itaconate, dimethyl itaconate, diethyl itaconate, dibutyl itaconate, di- (2-ethylhexyl) itaconate and other itaconic acid derivatives, butyl oleate, Oleic acid derivatives such as glyceryl monooleate and diethylene glycol monooleate, methylacetyl ricinoleate, butyl acetyl ricinoleate, glyceryl monoricinoleate, ricinoleic acid derivatives such as diethylene glycol monoricinoleate, n-butyl stearate, glycerin monostearate, diethylene glycol Stearic acid derivatives such as distearate, diethylene glycol monolaurate, diethylene glycol dipelargonate, pentaerythrate Other fatty acid derivatives such as lysyl fatty acid ester, triethyl phosphate, tributyl phosphate, tri- (2-ethylhexyl) phosphate, tributoxyethyl phosphate, triphenyl phosphate, cresyl diphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, tris. Phosphoric acid derivatives such as (chloroethyl) phosphate, diethylene glycol dibenzoate, dipropylene glycol dibenzoate, triethylene glycol dibenzoate, triethylene glycol di-
(2-ethyl butyrate), triethylene glycol di- (2-ethylhexoate), glycol derivative such as dibutylmethylene bisthioglycolate, glycerol monoacetate, glycerol triacetate, glycerol derivative such as glycerol tributyrate, epoxy Soybean oil, Epoxy butyl stearate, Epoxy hexahydrophthalate di-2-ethylhexyl, Epoxy hexahydrophthalate diisodecyl, Epoxy triglyceride, Epoxidized octyl oleate, Epoxidized decyl oleate and other epoxy derivatives, Adipic acid polyester , Polyester plasticizers such as sebacic acid polyesters and phthalic acid polyesters, partially hydrogenated terphenyls, adhesive plasticizers, and the like. These plasticizers may be used alone or in combination of two or more.

These plasticizers are usually added in an amount of 20 to 100 relative to 100 parts by weight of the epoxy group-containing vinyl chloride resin.
It is used in an amount of 40 parts by weight, preferably 40 to 80 parts by weight. If the amount of this plasticizer is too large, the physical properties deteriorate, and if it is too small, it becomes hard, which is not preferable. On the other hand, the foaming agent has a foaming decomposition temperature of 100 ° C or higher, preferably 18 ° C.
An organic decomposition type foaming agent in the range of 0 to 230 ° C. is essential. Further, an inorganic decomposition type foaming agent having a foaming decomposition temperature of 100 ° C. or higher may be used in combination. If desired, a freon, a vaporizing agent such as carbon dioxide gas, a high temperature expansion type microcapsule, a mechanical foaming method, etc. can be used together with this decomposition type foaming agent.

The reason why the organic decomposable foaming agent is preferable among decomposable foaming agents is not necessarily clear, but it is considered that the decomposed product of the foaming agent promotes crosslinking of epoxy groups. Examples of the organic decomposing type foaming agent include azo foaming agents such as azodicarbonamide and azobisformamide, dinitrosopentamethylenetetramine, benzenesulfonylhydrazide, toluenesulfonylhydrazide, p, p′-hydroxybenzenesulfonylhydrazide. And the like are preferable. These organic decomposable foaming agents can be used in combination with a foaming accelerator, and preferable foaming accelerators include, for example, zinc oxide, lead stearate, cadmium stearate, zinc stearate, barium stearate and sodium-based foaming accelerators. Examples thereof include potassium compounds and urea.

In order to obtain a fine foam having a uniform cell diameter and a rigid cell film thickness, it is preferable that the foaming agent particles have a small particle diameter. In particular, in order to effectively obtain an optimum bubble diameter of 0.1 to 0.6 mm, preferably around 0.3 mm, against the back pressure in the matrix polymer, 30 μm or less, preferably 20 μm.
Those having a uniform particle size of m or less are advantageous. A foaming agent other than an organic or inorganic decomposable foaming agent, or 1
When a foaming agent having a decomposition temperature of less than 00 ° C. is used, there are problems that the expansion ratio does not increase and it is difficult to obtain a homogeneous foam. The amount of the foaming agent to be added is usually 0.5 to 30 parts by weight, preferably 1 to 25 parts by weight, based on 100 parts by weight of the epoxy group-containing vinyl chloride resin. If this amount is less than 0.5 parts by weight, the foaming is insufficient, and if it exceeds 30 parts by weight, the degree of foaming does not change much relative to the amount, which is rather economically disadvantageous. When an inorganic decomposition-type foaming agent having a foaming decomposition temperature of 100 ° C. or higher is used in combination, the compounding amount of the inorganic decomposition-type foaming agent is
It is used in an amount equal to or less than that of an organic decomposition type foaming agent having a foaming decomposition temperature of 100 ° C. or higher.

If desired, a surfactant may be used in combination in order to obtain a good cell structure. The surfactant is preferably an ionic one, particularly an anionic one, and examples thereof include alkyl sulfate salts such as sodium lauryl sulfate and sodium myristyl sulfate, sodium dodecylbenzenesulfonate, potassium dodecylbenzenesulfonate and the like. Alkylaryl sulfonates, dioctyl sodium sulfosuccinate, sodium dihexyl sulfosuccinate, and other sulfosuccinate salts, ammonium laurate, fatty acid salts such as potassium stearate, polyoxyethylene alkyl sulfates, polyoxyethylene alkyl aryl sulfates , Rosin acid salts and the like can be used. The amount of these surfactants to be blended is usually 0.05 to 5 parts by weight, preferably 0.2 to 100 parts by weight of the epoxy group-containing vinyl chloride resin.
It is selected in the range of 3.0 parts by weight.

The epoxy group-containing vinyl chloride resin used in the present invention may be added with a plasticizer, a foaming agent, and if desired, a heat stabilizer, an ultraviolet absorber, an antioxidant and the like. There is no particular limitation on the heat stabilizer,
Any of those generally used for vinyl chloride resins can be selected and used. Further, an epoxy resin, a (meth) acrylic resin, or a resin having a functional group such as a carboxyl group or an amino group capable of bonding with an epoxy group can be added. Examples of such materials include Ba-Zn-based, Ca-Zn-based, Ca-Ba-
Preferable examples include Zn-based, Cd-Ba-Zn-based, Pb-based metal soaps, alkylated tin compounds of fatty acids such as butyltin laurate, butyltin malate, and octyltin malate. In addition, stabilizers such as kiletter and epoxidized soybean oil may be used together with these. Furthermore, non-metal stabilizers such as nitrilotripropionic acid tributylamide, 2,3-dichloroaniline and epoxy stabilizers can be used in combination.

The UV absorber is preferably a benzotriazole type, for example, 2 (2'-hydroxy-5'-methylphenyl) benzotriazole, 2 (2'-hydroxy-3'-tert-butyl-5'-methylphenyl). )
-5-chlorobenzotriazole, 2 (2'-hydroxy-3 ', 5'-ditertiary-butylphenyl) -5-chloro-benzotriazole, 2 (2'-hydroxy-4'
-Octoxyphenyl) benzotriazole and the like, and hindered amine light stabilizers and the like can also be preferably used.

The antioxidant is preferably a phenolic antioxidant, for example, 2,6-ditertiary-butyl-
p-cresol, 2,2'-methylenebis (4-methyl-
6-tert-butylphenol), 4,4'-butylidenebis (3-methyl-6-tert-butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol) and the like can be used.
Further, if necessary, a thickener, a diluent, a colorant, a filler such as calcium carbonate, clay, talc, etc., a silane-based or titanate-based coupling agent, etc. can be optionally added.

In the present invention, the epoxy group-containing vinyl chloride resin, the plasticizer, the foaming agent, and various additives used as desired are kneaded at a temperature at which the foaming agent does not decompose, and if necessary, For example, after degassing to prepare a plastisol, the plastisol is coated on a substrate or poured into a mold, and preferably heated at a temperature in the range of 130 to 220 ° C. for about 30 seconds to 10 minutes, By foaming, a vinyl chloride resin foam having a desired high expansion ratio can be obtained. At this time, as a kneading device, for example, a Hobart mixer, a kneader, a Henschel mixer or the like can be used, and as a heating device, for example, hot air circulation heating, (far) infrared heating, dielectric heating, induction heating or the like can be used. A heating device used for paste processing can be used.

[0021]

EXAMPLES Next, the present invention will be described in more detail by way of examples.
However, the present invention is in no way limited by these examples.
Not a thing. In addition, each characteristic was calculated | required as follows. (1) Surface epoxy of epoxy group-containing vinyl chloride resin
Base concentration 5 g of resin, 1 ml of 1N hydrochloric acid aqueous solution and 100 ml of methanol
300ml in a wide-mouth glass container with a stopper, magnetically
After mixing with a stirrer for 1 hour, sonicate at 40 ° C
And titrate it with 1 / 10N KOH alcohol solution.
(Titration aml). On the other hand, the same operation without resin
Measure the blank titer (b ml) by
The surface epoxy group concentration was determined. Surface epoxy group concentration (wt%) = 43 x (ba) f₂× 0.1 / w × 10^-1  f₂: Factor of 1/10 N KOH solution w: Weight of sample (g)

(2) of epoxy group-containing vinyl chloride resin
Total epoxy group concentration 1 g of epoxy group-containing resin is 100 ml of methyl ethyl ketone
300 ml of 1N hydrochloric acid solution 2 ml dissolved in
Put in a wide-mouthed glass container with a magnetic stirrer 1
After mixing for 1 hour, dissolve 1 / 10N KOH in alcohol
Titrate with liquid (titer aml). On the other hand, without resin
Perform the same operation to titrate the blank titer (b ml),
Calculate the epoxy content (% by weight) in the resin by the following formula
It was Total epoxy group concentration (wt%) = 43 x (ba) f₂× 0.1 / w × 10^-1  f₂: Factor of 1/10 N KOH solution w: Weight of sample (g)

(3) Change with time of viscosity of plastisol Plastisol was stored at 23 ° C. for 7 days, and the ratio of the viscosity to the initial viscosity after 7 days was determined. (4) Expansion ratio of foam The expansion ratio was determined by the following formula. Foaming ratio = foaming layer thickness / application thickness (semi-cure layer thickness)

(5) Heat shrinkage value of the foamed body It was heated at 230 ° C. for 60 seconds, and the heat shrinkage value was determined by the following formula. Heat shrinkage value = thickness after heating / thickness before heating (6) THF solubility of foam A 1 cm square foam sheet was immersed in tetrahydrofuran (THF), and the state of the sheet after standing at 23 ° C. for one day was visually observed.

Production Example 1 Production of PVC-1 A 1000-liter stainless steel autoclave was charged with 160 parts of deionized water, 0.4 part of dioctylsulfosuccinate sodium, 1 part of lauryl alcohol and 0.4 part of lauroyl peroxide and depressurized. After degassing, 97 parts of vinyl chloride was charged and an emulsion was obtained with stirring. The mixture was homogenized with a homogenizer, transferred to another deaerated 1000 liter autoclave, and heated to 45 ° C to initiate polymerization. At 5 hours after the temperature was raised, the polymerization rate was 40.
%, 3 parts of glycidyl methacrylate was continuously injected into the autoclave during the polymerization for 3 hours from this time, and the polymerization was terminated after 12 hours.
After unreacted monomer was collected under reduced pressure, the reaction solution was dried by a spray dryer and pulverized to obtain PVC-1.

Production Example 2 Production of PVC-2 A 1000-liter stainless steel autoclave was charged with 160 parts of deionized water, 0.4 part of sodium dioctyl sulfosuccinate, 1 part of lauryl alcohol and 0.4 part of lauroyl peroxide. After degassing, 97 parts of vinyl chloride was charged and an emulsion was obtained with stirring. The mixture was homogenized with a homogenizer, transferred to another deaerated 1000 liter autoclave, and heated to 60 ° C. to initiate polymerization. The polymerization rate was 40 at 4 hours after the temperature was raised.
%, 3 parts of glycidyl methacrylate was continuously injected into the autoclave during the polymerization for 3 hours from this time, and the polymerization was terminated 10 hours later. After recovering unreacted monomers under reduced pressure, the reaction solution was dried by a spray dryer and pulverized to obtain PVC-2.

Production Example 3 Production of PVC-4 A 1000-liter stainless steel autoclave was charged with 160 parts of deionized water, 0.4 part of sodium dioctylsulfosuccinate, 1 part of lauryl alcohol and 0.4 part of lauroyl peroxide and depressurized. After degassing, 90 parts of vinyl chloride was charged and an emulsion was obtained with stirring. The mixture was homogenized with a homogenizer, transferred into another deaerated 1000 liter autoclave, and heated to 45 ° C. to initiate polymerization. Immediately after the temperature was raised, 10 parts of glycidyl methacrylate was continuously injected into the autoclave during the polymerization for 10 hours, and the polymerization was terminated after 12 hours. After recovering unreacted monomer under reduced pressure, the reaction solution was dried by a spray dryer and pulverized to obtain PVC-4.

Production Example 4 Production of PVC-5 In Production Example 1, the amount of vinyl chloride charged was 98 parts, and the amount of glycidyl methacrylate added continuously was 2 parts. PVC-5 was obtained in the same manner as in Production Example 1 except that continuous injection was performed for 8 hours.

Examples 1 to 4 and Comparative Examples 1 to 5 Components of the types and amounts shown in Table 1 were put in a vacuum high-speed defoaming machine, mixed and defoamed to obtain plastisol. This plastisol was applied on two sheets of flame-retardant paper to a thickness of 50 μm and 500 μm, respectively, and then 45 ° C. at 150 ° C.
It was heated for 2 seconds to obtain a semi-cure sheet. Next, this semi-cure sheet was heated at 210 ° C. for 60 seconds to form a foam. The respective characteristics are shown in Table 1. The average particle size of the azodicarbonamide used in the examples is 1 to 1
The particles were 0 μm.

The symbols of the components in Table 1 have the following meanings. PVC1: Epoxy group-containing polyvinyl chloride average particle size 0.9 μm, average degree of polymerization 820, surface epoxy group concentration 0.09% by weight, total epoxy group concentration 0.92% by weight PVC2: epoxy group-containing polyvinyl chloride average particle size 1.0 μm, average degree of polymerization 1250, surface epoxy group concentration 0.10% by weight, total epoxy group concentration 1.03% by weight PVC3: polyvinyl chloride, ZEON resin 65 (manufactured by ZEON CORPORATION, trade name) PVC4: containing epoxy groups Polyvinyl chloride, average particle size 1.0 μm, average degree of polymerization 1200, surface epoxy group concentration: 0.1% by weight, total epoxy group concentration 2.7% by weight PVC5: epoxy group-containing polyvinyl chloride, average particle size 0. 8 μm, average degree of polymerization 1600, surface epoxy group concentration:
0.006% by weight, total epoxy group concentration 0.7% by weight DOP: dioctyl phthalate DBSNa: sodium dodecylbenzene sulfonate

[0031]

[Table 1]

[0032]

[Table 2]

Note 1) Using a rotational viscometer, shear rate 1se
measured at c ^-1

[0034]

According to the method of the present invention, a crosslinked foamed product of a vinyl chloride resin having a high expansion ratio and excellent physical properties can be easily produced under normal pressure without using a crosslinking agent.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] May 14, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

In the present invention, the epoxy group-containing vinyl chloride resin has an epoxy group concentration on the surface of the resin particles of 1 × 10 ⁻² wt% or more, preferably 5 × 1.
0 ^{−2 to} 5 × 10 ⁻¹ wt%, and the epoxy group concentration of the entire resin particles is 10 wt% or less, preferably 0.5.
.About.5% by weight is required. When the epoxy group concentration on the surface of the resin particles is less than 1 × 10 ⁻² wt%, the crosslinkability is poor, and when the total epoxy group concentration exceeds 10 wt%, the plastisol has a high viscosity, which is not desirable. The surface epoxy group concentration and the total epoxy group concentration can be measured by the method described below. Further, it is particularly preferable that the epoxy group-containing vinyl chloride resin has a higher epoxy group concentration in the outer shell portion of the particle than the epoxy group concentration in the inner core portion of the particle. When the epoxy group concentration on the particle surface satisfies the requirements of the present invention, and the polymerization is carried out so that the epoxy group concentration in the entire particle becomes uniform, the epoxy group-containing monomer unit is in a large amount, so that the polymer particle of the plasticizer is Swelling becomes remarkable, and the increase in the viscosity of plastisol and the increase in viscosity over time tend to increase.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0032

[Correction method] Change

[Correction content]

[0032]

[Table 2]

Claims (2)

[Claims] 1. An epoxy group-containing vinyl chloride resin having an average particle size of 0.05 to 5 μm, in which the epoxy group concentration on the particle surface is 1 × 10 ⁻² % by weight or more and the total epoxy group concentration is 10% by weight or less. In addition, an organic foaming agent having a foaming decomposition temperature of 100 ° C. or higher and a plasticizer are kneaded at a temperature at which the foaming agent does not decompose, and then heat-foam-molded to produce a vinyl chloride resin foam. Method. 2. Epoxy group-containing vinyl chloride resin particles,
The method for producing a vinyl chloride resin foam according to claim 1, wherein the epoxy group concentration of the outer shell portion of the particle is higher than the epoxy group concentration of the inner core portion of the particle.