JP2023109594A - Foamed vinyl chloride resin sheet and manufacturing method thereof - Google Patents

Abstract

An object of the present invention is to provide a foamed vinyl chloride resin sheet having excellent foaming characteristics and mechanical properties such as tensile strength and extensibility, and a method for producing the same.
The elastic resin contains a vinyl chloride resin, an elastic resin having an SP value of 7.5 to 11.0, and a plasticizer, and the elastic resin is 100 parts by mass in total of the vinyl chloride resin and the elastic resin. It is a foamed vinyl chloride resin sheet containing 0.8 to 16 parts by mass per 100 parts, and a method for producing the same.
[Selection figure] None

Description

TECHNICAL FIELD The present invention relates to a foamed vinyl chloride resin sheet and a method for producing the same.

Foamed vinyl chloride resin sheets are used in various applications such as wallpaper (wall material), building materials such as tile carpet (floor material), and stationery such as book covers. Various proposals have been made for wallpaper comprising such a foamed vinyl chloride resin sheet for the purpose of improving its functionality (see Patent Documents 1 to 3).

Japanese Patent Application Laid-Open No. 2006-187928 Japanese Patent Application Laid-Open No. 2003-301385 JP 2014-109087 A

Building materials such as wallpaper are required to have a mechanical strength that can prevent cracks caused by shrinkage, displacement, and distortion of the substrate. Stationery such as book covers are also required to have excellent mechanical strength.

An object of the present invention is to provide a foamed vinyl chloride resin sheet having excellent foaming characteristics and mechanical properties such as tensile strength and elongation, and a method for producing the same.

In order to improve the mechanical strength of the foamed vinyl chloride resin sheet, the present inventors tried to blend an elastic resin such as fluororubber (FKM) into the vinyl chloride resin, but sufficient foaming characteristics were obtained. We faced problems such as being unable to obtain the expected mechanical properties.
As a result of further intensive research by the present inventors, it was found that by blending an elastic resin having a specific SP value with a vinyl chloride resin at a predetermined ratio, it is possible to maintain sufficient foaming characteristics of the foamed vinyl chloride resin sheet. , tensile strength, elongation and other mechanical properties can be improved, and have completed the present invention. Furthermore, the present inventors have found that a foamed vinyl chloride resin sheet exhibits excellent stress relaxation properties by blending an elastic resin having a specific SP value at a predetermined ratio.

That is, the present invention is as follows.
[1] Contains a vinyl chloride resin, an elastic resin having an SP value of 7.5 to 11.0, and a plasticizer, and the elastic resin is contained in a total amount of 100 parts by mass of the vinyl chloride resin and the elastic resin. A foamed vinyl chloride resin sheet characterized by containing 0.8 to 16 parts by mass.

[2] The foamed vinyl chloride resin sheet according to [1] above, wherein the vinyl chloride resin has a viscosity average degree of polymerization of 450 to 1,800.
[3] The foamed vinyl chloride according to [1] or [2] above, wherein the elastic resin is at least one selected from butadiene rubber, thermoplastic polyurethane, chloroprene rubber, and chlorinated polyethylene. based resin sheet.

[4] A method for producing a foamed vinyl chloride resin sheet according to any one of the above [1] to [3], comprising a vinyl chloride resin and an SP value of 7.5 to 11.0 A method for producing a foamed vinyl chloride resin sheet, which comprises kneading an elastic resin and a plasticizer, molding the resulting kneaded product into a sheet, and then foaming the obtained sheet.
[5] The method for producing a foamed vinyl chloride resin sheet according to [4] above, wherein the sheet molding is calendar molding.

The foamed vinyl chloride resin sheet of the present invention is excellent in foaming characteristics and mechanical properties such as tensile strength and elongation.

[Foamed vinyl chloride resin sheet]
The foamed vinyl chloride resin sheet of the present invention contains a vinyl chloride resin, an elastic resin having an SP value of 7.5 to 11.0 (hereinafter simply referred to as an elastic resin), and a plasticizer. , 0.8 to 16 parts by mass per 100 parts by mass of the total amount of vinyl chloride resin and elastic resin.

The foamed vinyl chloride resin sheet of the present invention is a foamed sheet having continuous or discontinuous voids, and has a porosity of, for example, 50% or more, preferably 55% or more. Also, the thickness of the sheet is, for example, about 0.1 to 10.0 mm.

The foamed vinyl chloride-based resin sheet of the present invention contains an elastic resin that is highly compatible with vinyl chloride-based resins, so that it has excellent foaming properties and excellent mechanical properties such as tensile strength and extensibility. Therefore, it is useful for building materials such as wallpaper and flooring, and stationery such as book covers. Specifically, the foamed vinyl chloride resin of the present invention is excellent in expansion ratio and foam cell denseness, and is also excellent in surface smoothness. In addition, the tensile strength and elongation are improved, and the surface strength is also increased. Furthermore, the foamed vinyl chloride resin sheet of the present invention is excellent in stress relaxation. That is, since the embossing reversion after embossing is small and excellent shape retention (pattern retention) is exhibited, it is suitable for wallpaper and floor materials, for example.

(vinyl chloride resin)
Examples of vinyl chloride-based resins in the present invention include suspension-based vinyl chloride-based resins, vinyl chloride-based resins for paste processing, and the like, and suspension-based vinyl chloride-based resins are preferable. These may be used in combination.

(Suspension vinyl chloride resin)
The suspension vinyl chloride resin may be a homopolymer of vinyl chloride or a copolymer mainly composed of vinyl chloride. Mainly composed of vinyl chloride means, for example, that vinyl chloride accounts for 50% by mass or more of the whole, preferably 70% by mass or more, and more preferably 90% by mass or more.

Examples of monomers copolymerizable with vinyl chloride include olefin compounds such as ethylene and propylene; vinyl esters such as vinyl acetate and vinyl propionate; unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid; unsaturated monocarboxylic acid esters such as methyl, ethyl acrylate, n-butyl acrylate, 2-hydroxyethyl acrylate, methyl methacrylate, ethyl methacrylate, and -N,N-dimethylaminoethyl methacrylate; acrylamide, Unsaturated amides such as methacrylamide; Unsaturated nitriles such as acrylonitrile and methacrylonitrile; Unsaturated dicarboxylic acids such as maleic acid and fumaric acid; Esters thereof and anhydrides thereof; N-substituted maleimides; vinyl ethers such as vinyl ethyl ether; vinylidene compounds such as vinylidene chloride;

The suspension vinyl chloride resin has a larger particle size than the vinyl chloride resin for paste processing, and usually has an average particle size (D50) of 50 to 200 μm. The average particle size (D50) is preferably 70-180 μm, more preferably 100-150 μm. This average particle diameter (D50) is indicated as a 50% passing diameter using a JIS Z8801 sieve according to JIS Z8815 (dry sieving test method).

The viscosity-average degree of polymerization of the suspension vinyl chloride resin is preferably 450-1800, more preferably 700-1800, even more preferably 800-1500. By setting the degree of polymerization within this range, the effects of the present invention can be effectively exhibited.
The average degree of polymerization is the reduced viscosity (K value) measured in accordance with JIS K7367-2 according to the vinyl chloride resin test method (published by the PVC Industry and Environment Association, April 2003), and the approximate expression: K value. = 20.42 x Ln (degree of polymerization) - 74.93.

The suspension vinyl chloride resin is porous, and its porosity (pore volume) is, for example, 0.05 to 0.45 ml/g, preferably 0.10 to 0.40 ml/g, More preferably 0.15 to 0.35 ml/g.
Porosity can be determined by a mercury intrusion method (porosimeter).

The suspension vinyl chloride resin of the present invention is obtained by polymerizing vinyl chloride alone or a monomer mixture comprising vinyl chloride and an unsaturated monomer copolymerizable therewith by a conventionally known method. can be done. For example, it can be obtained by suspension polymerization. By appropriately setting various reaction conditions such as temperature, type and amount of dispersant, and stirring speed, a resin having a desired degree of polymerization and porosity can be obtained.

(Vinyl chloride resin for paste processing)
Vinyl chloride resins for paste processing include homopolymers of vinyl chloride and copolymers mainly composed of vinyl chloride, as in suspension vinyl chloride resins.

Vinyl chloride resins for paste processing are usually fine particles having a particle size smaller than that of suspension vinyl chloride resins and having an average primary particle size (D50) of 0.1 to 10 μm. The average particle diameter (D50) is preferably 0.1-5.0 μm, more preferably 0.5-3.0 μm.
The average particle size (D50) means the particle size at the 50% point in the cumulative volume distribution curve with the total volume of the particle size distribution determined on a volume basis as 100%, that is, the volume-based cumulative 50% diameter. The particle size distribution can be determined by a laser diffraction/scattering particle size distribution analyzer (eg LA-960 manufactured by Horiba, Ltd.).

The viscosity average degree of polymerization of the vinyl chloride resin for paste processing is preferably 450-1800, more preferably 700-1800, even more preferably 800-1500. By setting the degree of polymerization within this range, the effects of the present invention can be effectively exhibited.
This viscosity-average degree of polymerization is calculated in the same manner as in the case of the suspension vinyl chloride resin.

The vinyl chloride resin for paste processing of the present invention is obtained by polymerizing vinyl chloride alone or a monomer mixture comprising vinyl chloride and an unsaturated monomer copolymerizable therewith by a conventionally known method. be able to. For example, it can be obtained by emulsion polymerization (including seeded emulsion polymerization).

(elastic resin)
The elastic resin in the present invention is an elastic resin having an SP value of 7.5 to 11.0 as described above. In the case of an elastic resin having an SP value outside this range, the density of foamed cells and surface smoothness are deteriorated, rubber elasticity is exhibited, and embossability is deteriorated. That is, since the elastic resin having the SP value in the present invention is well compatible with the vinyl chloride resin, it is possible to maintain the excellent foaming properties of the vinyl chloride resin, and to properties) can be suppressed to maintain the excellent stress relaxation properties of vinyl chloride resins. The SP value is preferably 8.0-10.5.

Specific examples of elastic resins include butadiene-based rubbers such as acrylonitrile-butadiene-based rubbers (NBR) and styrene-butadiene-based rubbers (SBR); thermoplastic polyurethanes (TPU); polyester-based thermoplastic elastomers (TPC). chloroprene rubber (CR); acrylic rubber (ACM); chlorosulfonated polyethylene (CSM); chlorinated polyethylene (CPE). Among these, butadiene-based rubber, thermoplastic polyurethane, chloroprene rubber, and chlorinated polyethylene are preferred, and acrylonitrile-butadiene-based rubber is particularly preferred. These may be used in combination of two or more.

The elastic resin in the foamed vinyl chloride resin sheet of the present invention is contained in an amount of 0.8 to 16 parts by mass per 100 parts by mass of the total amount of the vinyl chloride resin and the elastic resin. If it is less than 0.8% by mass, sufficient improvement in mechanical properties such as tensile strength and elongation is not observed. On the other hand, if it exceeds 16% by mass, the foaming property is deteriorated, the rubber-like property becomes dominant, and the stress relaxation property is deteriorated. The elastic resin is preferably contained in an amount of 1 to 15 parts by mass, more preferably 1 to 10 parts by mass, per 100 parts by mass of the total amount of the vinyl chloride resin and the elastic resin.

(Plasticizer)
Conventionally known plasticizers can be used as the plasticizer in the present invention.

In the present invention, for example, dibutyl phthalate, di-(2-ethylhexyl) phthalate, di-n-octyl phthalate, diisobutyl phthalate, diheptyl phthalate, diphenyl phthalate, diisodecyl phthalate, diundecyl phthalate, butylbenzyl phthalate, dinonyl phthalate , dicyclohexyl phthalate and other phthalic acid derivatives; di-(2-ethylhexyl) isophthalate, diisooctyl isophthalate, diisononyl phthalate and other isophthalic acid derivatives; di-(2-ethylhexyl) tetrahydrophthalate, di-n-octyl tetrahydrophthalate , diisodecyltetrahydrophthalate and other tetrahydrophthalic acid derivatives; di-n-butyl adipate, di-(2-ethylhexyl)adipate, diisodecyladipate, diisononyl adipate and other adipic acid derivatives; di-(2-ethylhexyl)azelate, diisooctyl azelaic acid derivatives such as azelate and di-n-hexyl azelate; sebacic acid derivatives such as di-n-butyl sebacate and di-(2-ethylhexyl) sebacate; di-n-butyl maleate, dimethyl maleate and diethyl maleate maleic acid derivatives such as ate, di-(2-ethylhexyl) maleate; fumaric acid derivatives such as di-n-butyl fumarate, di-(2-ethylhexyl) fumarate; tri-(2-ethylhexyl) trimellitate, tri-n - trimellitic acid derivatives such as octyl trimellitate, triisodecyl trimellitate, triisooctyl trimellitate, tri-n-hexyl trimellitate, triisononyl trimellitate; tetra-(2-ethylhexyl) pyromellitate , pyromellitic acid derivatives such as tetra-n-octyl pyromellitate; citric acid derivatives such as triethyl citrate, tri-n-butyl citrate, acetyl triethyl citrate, acetyl tri-(2-ethylhexyl) citrate; monomethyl itaco itaconic acid derivatives such as diethyl itaconate, monobutyl itaconate, dimethyl itaconate, diethyl itaconate, dibutyl itaconate, di-(2-ethylhexyl) itaconate; oleic acid such as butyl oleate, glyceryl monooleate, diethylene glycol monooleate derivatives; ricinoleic acid derivatives such as glyceryl monoricinoleate and diethylene glycol monoricinolate; stearic acid derivatives such as glycerin monostearate and diethylene glycol distearate; Fatty acid derivatives; phosphoric acid derivatives such as triethyl phosphate, tributyl phosphate, tri-(2-ethylhexyl) phosphate, triphenyl phosphate, cresyl diphenyl phosphate, tricresyl phosphate, tris(chloroethyl) phosphate; diethylene glycol dibenzoate, dipropylene glycol Glycol derivatives such as dibenzoate, triethylene glycol dibenzoate, and dibutylmethylene bisthioglycolate; glycerin derivatives such as glycerol monoacetate, glycerol triacetate, and glycerol tributyrate; adipic acid-based polyesters, sebacic acid-based polyesters, phthalic acid-based polyesters or partially hydrogenated terphenyl, adhesive plasticizers; further polymerizable plasticizers such as diallyl phthalate, acrylic monomers and oligomers, and the like. Two or more of these plasticizers may be used in combination.

(other ingredients)
In addition to the vinyl chloride resin, the elastic resin and the plasticizer, the foamed vinyl chloride resin sheet of the present invention may contain other various components. Other components include, for example, heat stabilizers, fillers, foaming accelerators, viscosity modifiers, adhesion imparting agents, colorants, diluents, ultraviolet absorbers, antioxidants, and reinforcing agents.

The foamed vinyl chloride resin sheet of the present invention is soft and can be used, for example, as a foamed resin layer for wall materials, floor materials, book covers, leather and the like.

[Method for producing foamed vinyl chloride resin sheet]
In the method for producing a foamed vinyl chloride resin sheet of the present invention, a vinyl chloride resin, an elastic resin having an SP value of 7.5 to 11.0, and a plasticizer are kneaded, and the resulting kneaded product is molded into a sheet. After that, the obtained sheet is foamed. According to this production method, the foamed vinyl chloride resin sheet of the present invention can be produced.

In the production method of the present invention, as described above, a raw vinyl chloride composition (compound or plastisol) obtained by kneading at least a vinyl chloride resin, an elastic resin and a plasticizer is used as a raw material. May be blended. For example, it is preferable to use a foaming agent in addition to the other components exemplified above.

Examples of foaming agents include inorganic foaming agents such as sodium bicarbonate, ammonium bicarbonate, ammonium nitrite, amide compounds, and sodium borohydride; isocyanate compounds, azo compounds, hydrazine derivatives, semicarbazide compounds, azide compounds, nitroso compounds, and triazoles. Examples include organic foaming agents such as compounds, and the like, and two or more thereof may be used in combination.

In addition, in the production method of the present invention, it is not always necessary to use a foaming agent, and examples thereof include the use of microcapsules, volatile liquids, and mechanical foaming.

Examples of the sheet molding method include calendar molding, extrusion molding, inflation molding, and the like, and the sheet molding can be performed efficiently and the effects of the present invention can be effectively exhibited. , calender molding is preferred. In calender molding, it is preferable to first put a composition containing a vinyl chloride resin and a plasticizer into an apparatus, and then add the elastic resin later during sheet molding. The heating temperature during sheet molding is not particularly limited as long as the starting vinyl chloride composition is melted and the foaming agent is not decomposed and foamed. is preferred.

After molding the sheet, if the sheet contains a foaming agent, the sheet is foamed by heating to a temperature at which the foaming agent foams. The heating temperature is not particularly limited as long as it decomposes the foaming agent, and is, for example, 110 to 230.degree.

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[Example 1]
99 parts by mass of a suspension vinyl chloride resin (ZEST 1000Z manufactured by Shin-Daiichi Vinyl Co., Ltd.) with a viscosity average polymerization degree of 1020 as a vinyl chloride resin, and di-(2-ethylhexyl) phthalate (Ltd. ) DOP manufactured by J Plus) 58 parts by mass, calcium carbonate 15 parts by mass, (Cellmic C-2 manufactured by Sankyo Kasei Co., Ltd.) 2.5 parts by mass as a foaming agent, and (Co., Ltd.) as a stabilizer ) SC-320 manufactured by ADEKA) 3 parts by mass and 1 part by mass of (Metabrene P-530A manufactured by Mitsubishi Chemical Corporation) as a processing aid, Henschel mixer (UM2E / I manufactured by Nippon Coke Industry Co., Ltd.) The mixture was mixed at 3000 rpm until the resin temperature was raised to 120° C. to prepare a vinyl chloride composition (compound).

The prepared vinyl chloride composition was put into a calendar molding machine, 1 part by mass of acrylonitrile-butadiene rubber (NBR) as an elastic resin was added during sheet molding, and the prepared sheet was heated to foam. A foamed vinyl chloride resin sheet according to 1 was produced.

[Example 2]
The foamed vinyl chloride resin according to Example 2 was prepared in the same manner as in Example 1, except that the compounded amount of the vinyl chloride resin was changed from 99 parts by mass to 95 parts by mass, and the compounded amount of the elastic resin was changed from 1 mass to 5 parts by mass. manufactured the sheet.
[Example 3]
The foamed vinyl chloride resin according to Example 3 was prepared in the same manner as in Example 1, except that the compounded amount of the vinyl chloride resin was changed from 99 parts by mass to 90 parts by mass, and the compounded amount of the elastic resin was changed from 1 mass to 10 parts by mass. manufactured the sheet.
[Example 4]
The foamed vinyl chloride resin according to Example 4 was prepared in the same manner as in Example 1, except that the compounded amount of the vinyl chloride resin was changed from 99 parts by mass to 85 parts by mass, and the compounded amount of the elastic resin was changed from 1 mass to 15 parts by mass. manufactured the sheet.

[Comparative Example 1]
Foaming according to Comparative Example 1 was performed in the same manner as in Example 1, except that the compounded amount of the vinyl chloride resin was changed from 99 parts by mass to 100 parts by mass, and the compounded amount of the elastic resin was changed from 1 mass to 0 parts by mass (no compounding). A vinyl chloride resin sheet was produced.
[Comparative Example 2]
Foamed vinyl chloride resin according to Comparative Example 2 was prepared in the same manner as in Example 1, except that the compounded amount of the vinyl chloride resin was changed from 99 parts by mass to 80 parts by mass, and the compounded amount of the elastic resin was changed from 1 mass to 20 parts by mass. manufactured the sheet.

[Example 5]
A foamed vinyl chloride resin sheet according to Example 5 was produced in the same manner as in Example 2, except that the vinyl chloride resin having a viscosity average polymerization degree of 1020 was changed to a vinyl chloride resin having a viscosity average polymerization degree of 460. .
[Example 6]
A foamed vinyl chloride resin sheet according to Example 6 was produced in the same manner as in Example 2, except that the vinyl chloride resin having a viscosity average polymerization degree of 1020 was changed to a vinyl chloride resin having a viscosity average polymerization degree of 810. .

[Example 7]
A foamed vinyl chloride resin sheet according to Example 7 was produced in the same manner as in Example 2 except that the vinyl chloride resin having a viscosity average polymerization degree of 1020 was changed to a vinyl chloride resin having a viscosity average polymerization degree of 1320. .
[Example 8]
A foamed vinyl chloride resin sheet according to Example 8 was produced in the same manner as in Example 2 except that the vinyl chloride resin having a viscosity average polymerization degree of 1020 was changed to a vinyl chloride resin having a viscosity average polymerization degree of 1740. .

[Comparative Example 3]
Foaming according to Comparative Example 3 was performed in the same manner as in Example 5, except that the compounded amount of the vinyl chloride resin was changed from 95 parts by mass to 100 parts by mass, and the compounded amount of the elastic resin was changed from 5 parts by mass to 0 parts by mass (no compounding). A vinyl chloride resin sheet was produced.
[Comparative Example 4]
Foaming according to Comparative Example 4 was performed in the same manner as in Example 6, except that the blending amount of the vinyl chloride resin was changed from 95 parts by mass to 100 parts by mass, and the blending amount of the elastic resin was changed from 5 parts by mass to 0 parts by mass (no blending). A vinyl chloride resin sheet was produced.

[Comparative Example 5]
Foaming according to Comparative Example 5 was performed in the same manner as in Example 7, except that the blending amount of the vinyl chloride resin was changed from 95 parts by mass to 100 parts by mass, and the blending amount of the elastic resin was changed from 5 parts by mass to 0 parts by mass (no blending). A vinyl chloride resin sheet was produced.
[Comparative Example 6]
Foaming according to Comparative Example 6 was performed in the same manner as in Example 8, except that the blending amount of the vinyl chloride resin was changed from 95 parts by mass to 100 parts by mass, and the blending amount of the elastic resin was changed from 5 parts by mass to 0 parts by mass (no blending). A vinyl chloride resin sheet was produced.

[Example 9]
A foamed vinyl chloride resin sheet according to Example 9 was produced in the same manner as in Example 2, except that acrylonitrile-butadiene rubber (NBR) as the elastic resin was changed to thermoplastic polyurethane (SBR).
[Example 10]
A foamed vinyl chloride resin sheet according to Example 10 was prepared in the same manner as in Example 2, except that acrylonitrile-butadiene rubber (NBR) as the elastic resin was changed to thermoplastic polyurethane (TPU) as the elastic resin. manufactured.
[Example 11]
A foamed vinyl chloride resin sheet according to Example 11 was prepared in the same manner as in Example 2, except that the elastic resin acrylonitrile-butadiene rubber (NBR) was changed to the elastic resin chloroprene rubber (CR). manufactured.

[Example 12]
A foamed vinyl chloride resin according to Example 12 was prepared in the same manner as in Example 2, except that the elastic resin acrylonitrile-butadiene rubber (NBR) was changed to the elastic resin chlorosulfonated polyethylene (CSM). manufactured the sheet.
[Example 13]
A foamed vinyl chloride resin sheet according to Example 13 was produced in the same manner as in Example 2, except that acrylonitrile-butadiene rubber (NBR) as the elastic resin was changed to acrylic rubber (ACM) as the elastic resin. manufactured.
[Example 14]
A foamed vinyl chloride resin sheet according to Example 14 was prepared in the same manner as in Example 2, except that the elastic resin acrylonitrile-butadiene rubber (NBR) was changed to the elastic resin chlorinated polyethylene (CPE). manufactured.

[Comparative Example 7]
Comparative Example 7 was carried out in the same manner as in Example 2, except that the elastic resin acrylonitrile-butadiene rubber (NBR) was changed to fluororubber (FKM), which is an elastic resin whose SP value is outside the scope of the present invention. A foamed vinyl chloride resin sheet according to was manufactured.

The foamed vinyl chloride resin sheets according to Examples 1 to 14 and Comparative Examples 1 to 7 were evaluated for tensile elongation, tensile strength, stress residual rate, foam cell compactness, surface smoothness, and expansion ratio by the following methods. bottom.

(Sample for tensile test)
Ten No. 1 dumbbell-type tensile test pieces were prepared from each of the foamed vinyl chloride resin sheets in the calendar roll direction (MD), and used as samples for the tensile test.

(Tensile elongation, tensile strength, stress residual rate)
Tensile elongation, tensile strength and stress residual rate of the tensile test sample were measured by Autograph (AGS-H manufactured by Shimadzu Corporation). In the tensile test, the tensile test sample was pulled at a grip distance of 40 mm and a test speed of 3 mm/min, and the elongation when the foamed vinyl chloride resin sheet started to break was divided by the grip distance to obtain the elongation rate. Also, the maximum stress before the foamed vinyl chloride resin sheet started to break was taken as the tensile strength, and the average value of n=5 was obtained. The stress retention rate is determined by pulling at a test speed of 40 mm / min until the distance between grips is 40 mm to 60 mm, the stress immediately after that is the initial stress σ ₀ , and the stress after 600 seconds is σ _t , stress retention = (σ _t /σ ₀ )×100, and the average value of n=5 was obtained.

(Evaluation of foam cell compactness)
The cross section of the foamed vinyl chloride resin sheet was observed with a CCD camera at a magnification of 50 times, and the denseness of the foamed cells was evaluated according to the following criteria.

◯: It has extremely dense and uniform foam cells.
Δ: Slightly rough or having non-uniform foam cells.
x: It has coarse foam cells.

(Surface smoothness)
Visual observation of the surface and magnified observation of the surface layer of the cross section were performed, and evaluation was made according to the following criteria.
○: Overall smooth △: Mostly smooth, but partially uneven ×: Overall uneven swelling and unevenness

(Expansion ratio)
The thickness was measured at arbitrary 5 points on the calender molded sheet prepared above, and the average value was taken as the thickness _L0 before foaming. In addition, for the foamed vinyl chloride resin sheet obtained by heating and foaming, the thickness was measured at the same five points where the thickness of the calendar molded sheet was measured, and the average value was taken as the thickness L after foaming, and the expansion ratio = L. /L ₀ .

The results are shown in Tables 1-3.

As shown in Tables 1 to 3, the foamed vinyl chloride resin sheets according to Examples 1 to 14 are excellent in tensile elongation rate, tensile strength and stress residual rate (stress relaxation property), and have a high expansion ratio. The denseness and surface smoothness of the cells were excellent. That is, a foamed vinyl chloride resin sheet having excellent mechanical properties and foaming properties was obtained. As shown in Table 2, the tensile elongation and tensile strength generally tend to improve when a vinyl chloride resin with a high degree of polymerization is used, but these properties are further improved by blending an elastic resin. Further, as shown in Table 3, in comparison with Example 12 (CSM) and Example 13 (ACM), Example 1 (NBR), Example 9 (SBR), and Example 1 using other elastic resins 10 (TPU), Example 11 (CR) and Example 14 (CPE) had better elongation properties. This is presumed to be due to the fact that, in the case of Examples 12 (CSM) and 13 (ACM), the resin was slightly hardened and a brittle surface was developed a little.

On the other hand, as shown in Table 1, even if the elastic resin is suitable as in Comparative Example 2, if the amount of the resin is too large, the stress residual rate will increase, the embossing characteristics will deteriorate, and the foaming characteristics will increase. also worsens. In addition, as shown in Table 3, the elastic resin having an SP value outside the range of the present invention as in Comparative Example 7 showed no improvement in tensile elongation and tensile strength, but the stress residual rate improved. and also the foaming properties are deteriorated.

The foamed vinyl chloride resin sheet of the present invention is industrially useful because it can be used for a foamed resin layer such as wallpaper.

Claims (5)

A vinyl chloride resin, an elastic resin with an SP value of 7.5 to 11.0, and a plasticizer,
A foamed vinyl chloride resin sheet, wherein the elastic resin is contained in an amount of 0.8 to 16 parts by mass based on 100 parts by mass of the total amount of the vinyl chloride resin and the elastic resin. 2. The foamed vinyl chloride resin sheet according to claim 1, wherein the vinyl chloride resin has a viscosity average degree of polymerization of 450 to 1,800. 3. The foamed vinyl chloride resin sheet according to claim 1, wherein the elastic resin is at least one selected from butadiene rubber, thermoplastic polyurethane, chloroprene rubber, and chlorinated polyethylene. A method for producing the foamed vinyl chloride resin sheet according to any one of claims 1 to 3,
A vinyl chloride resin, an elastic resin having an SP value of 7.5 to 11.0, and a plasticizer are kneaded, the resulting kneaded product is formed into a sheet, and the obtained sheet is foamed. A method for producing a foamed vinyl chloride resin sheet. 5. The method for producing a foamed vinyl chloride resin sheet according to claim 4, wherein the sheet molding is calendar molding.