Foamed vinyl chloride resin sheet and method for producing same

Abstract

To provide a foamed polyvinyl chloride resin sheet that has excellent foaming properties and also has excellent mechanical properties such as tensile strength and elongation, and a method for producing the same.SOLUTION: A foamed polyvinyl chloride resin sheet contains a polyvinyl chloride resin, an elastic resin with an SP value of 7.5-11.0, and a plasticizer. The content of the elastic resin is 0.8-16 pts.mass relative to 100 pts.mass of the total of the polyvinyl chloride resin and elastic resin. There is also provided a method for producing the same.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a foamed vinyl chloride resin sheet and a method for producing the same. [Background technology]

[0002] Foamed vinyl chloride resin sheets are used in a variety of applications, such as building materials such as wallpaper (wall material) and tile carpet (floor material), and stationery such as book covers, etc. Regarding wallpapers provided with such foamed vinyl chloride resin sheets, various proposals have been made with the aim of improving their functionality (see Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-187928 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-301385 [Patent Document 3] Japanese Patent Application Laid-Open No. 2014-109087 Summary of the Invention [Problem to be solved by the invention]

[0004] Wallpaper and other building materials require mechanical strength to prevent cracks caused by shrinkage, shifting, and distortion of the substrate. Excellent mechanical strength is also required for stationery such as book covers.

[0005] An object of the present invention is to provide a foamed vinyl chloride resin sheet which has excellent foaming properties and mechanical properties such as tensile strength and elongation, and a method for producing the same. [Means for solving the problem]

[0006] The inventors attempted to compound an elastic resin such as fluororubber (FKM) with a polyvinyl chloride resin in order to improve the mechanical strength of a foamed polyvinyl chloride resin sheet, but encountered problems such as insufficient foaming characteristics and inability to obtain the expected mechanical properties. As a result of further intensive research, the present inventors discovered that by blending a vinyl chloride resin with an elastic resin having a specific SP value in a predetermined ratio, it is possible to improve mechanical properties such as tensile strength and elongation while maintaining sufficient foaming characteristics of a foamed vinyl chloride resin sheet, thereby completing the present invention. Furthermore, the present inventors discovered that by blending a vinyl chloride resin with an elastic resin having a specific SP value in a predetermined ratio, the foamed vinyl chloride resin sheet exhibits excellent stress relaxation properties.

[0007] That is, the present invention is as follows. [1] A foamed polyvinyl chloride resin sheet comprising a polyvinyl chloride resin, an elastic resin having an SP value of 7.5 to 11.0, and a plasticizer, wherein the elastic resin is contained in an amount of 0.8 to 16 parts by mass per 100 parts by mass of the total amount of the polyvinyl chloride resin and the elastic resin.

[0008] [2] The foamed vinyl chloride resin sheet according to the above [1], wherein the vinyl chloride resin has a viscosity-average degree of polymerization of 450 to 1,800. [3] The foamed polyvinyl chloride resin sheet according to [1] or [2] above, characterized in that the elastic resin is at least one selected from butadiene rubber, thermoplastic polyurethane, chloroprene rubber, and chlorinated polyethylene.

[0009] [4] A method for producing a foamed vinyl chloride resin sheet according to any one of [1] to [3] above, comprising kneading a vinyl chloride resin, an elastic resin having an SP value of 7.5 to 11.0, and a plasticizer, molding the resulting kneaded mixture into a sheet, and then foaming the resulting sheet. [5] The method for producing a foamed polyvinyl chloride resin sheet according to the above item [4], characterized in that the sheet molding is calendar molding. [Effects of the Invention]

[0010] The foamed vinyl chloride resin sheet of the present invention has excellent foaming properties and also excellent mechanical properties such as tensile strength and elongation. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Polyvinyl chloride foam 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 elastic resin), and a plasticizer, and the elastic resin 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.

[0012] The foamed vinyl chloride resin sheet of the present invention is a foamable sheet having continuous or discontinuous voids, a porosity of, for example, 50% or more, preferably 55% or more, and a sheet thickness of, for example, about 0.1 to 10.0 mm.

[0013] The foamed vinyl chloride resin sheet of the present invention contains an elastic resin that is compatible with the vinyl chloride resin, and therefore has excellent foaming characteristics and mechanical properties such as tensile strength and elongation. Therefore, it is useful for building materials such as wallpaper and flooring, and for stationery such as book covers. Specifically, the foamed vinyl chloride resin of the present invention has excellent expansion ratio, foam cell density, and surface smoothness. It also has improved tensile strength and elongation, and high surface strength. Furthermore, the foamed vinyl chloride resin sheet of the present invention has excellent stress relaxation properties. That is, it exhibits little embossing return after embossing and excellent shape retention (pattern retention), making it suitable for wallpaper and flooring applications, for example.

[0014] (Vinyl chloride resin) Examples of vinyl chloride resins in the present invention include suspension vinyl chloride resins and vinyl chloride resins for paste processing, with suspension vinyl chloride resins being preferred. These may be used in combination.

[0015] (Suspension vinyl chloride resin) Suspension vinyl chloride resins include vinyl chloride homopolymers. is used.

[0017] Suspension vinyl chloride resins have larger particle sizes than paste vinyl chloride resins, and typically have an average particle size (D50) of 50 to 200 μm. The average particle size (D50) is preferably 70 to 180 μm, and more preferably 100 to 150 μm. This average particle size (D50) is expressed as the 50% passing diameter using a JIS Z8801 sieve according to JIS Z8815 (dry sieving test method).

[0018] The viscosity-average degree of polymerization of the suspension vinyl chloride resin is preferably 450 to 1800, more preferably 700 to 1800, and even more preferably 800 to 1500. When the degree of polymerization is within this range, the effects of the present invention can be effectively exhibited. The average degree of polymerization is calculated by converting the reduced viscosity (K value) measured in accordance with JIS K7367-2 in accordance with the measurement method of the Vinyl Chloride Resin Test Method (published by the PVC Industry and Environment Association in April 2003) using the approximate formula: K value = 20.42 × Ln (degree of polymerization) - 74.93.

[0019] 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, and more preferably 0.15 to 0.35 ml / g. The porosity can be determined by mercury intrusion porosimetry (porosimeter).

[0020] The suspension vinyl chloride resin of the present invention is a vinyl chloride resin. Lu The resin can be obtained by polymerization using a conventionally known method, such as suspension polymerization. By appropriately setting various reaction conditions such as temperature, type and amount of dispersant, and stirring speed, a resin with the desired degree of polymerization and porosity can be obtained.

[0021] (Vinyl chloride resin for paste processing) PVC resins for paste processing are vinyl chloride homopolymers, similar to suspension vinyl chloride resins. is used.

[0022] The vinyl chloride resin for paste processing usually has a smaller particle size than the suspension vinyl chloride resin, and is in the form of fine particles with an average primary particle size (D50) of 0.1 to 10 μm. The average particle size (D50) is preferably 0.1 to 5.0 μm, and more preferably 0.5 to 3.0 μm. The average particle size (D50) is the particle size at 50% on a cumulative volume distribution curve, where the total volume of the particle size distribution determined on a volume basis is 100%, i.e., the volume-based cumulative 50% diameter. The particle size distribution can be determined using a laser diffraction / scattering particle size distribution analyzer (e.g., LA-960 manufactured by Horiba, Ltd.).

[0023] The viscosity-average degree of polymerization of the vinyl chloride resin for paste processing is preferably 450 to 1800, more preferably 700 to 1800, and even more preferably 800 to 1500. When the degree of polymerization is 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 suspension vinyl chloride resins.

[0024] The vinyl chloride resin for paste processing of the present invention is Lu The copolymer can be obtained by polymerization using a conventionally known method, for example, emulsion polymerization (including seed emulsion polymerization).

[0025] (elastic resin) As described above, the elastic resin in the present invention is an elastic resin having an SP value of 7.5 to 11.0. If the SP value of the elastic resin is outside this range, the density of the foam cells and the surface smoothness will deteriorate, and rubber elasticity will be exhibited, resulting in poor embossability. That is, the elastic resin with the SP value in the present invention is well compatible with the vinyl chloride resin, and therefore can maintain the excellent foaming properties of the vinyl chloride resin while suppressing the rubber-like properties (embossing return property) that are characteristic of the elastic resin, thereby maintaining the excellent stress relaxation properties of the vinyl chloride resin. The SP value is preferably 8.0 to 10.5.

[0026] Specific examples of elastic resins include butadiene rubbers such as acrylonitrile-butadiene rubber (NBR) and styrene-butadiene rubber (SBR); thermoplastic polyurethane (TPU); polyester-based thermoplastic elastomers (TPC); chloroprene rubber (CR); acrylic rubber (ACM); chlorosulfonated polyethylene (CSM); and chlorinated polyethylene (CPE). Among these, butadiene rubber, thermoplastic polyurethane, chloroprene rubber, and chlorinated polyethylene are preferred, with acrylonitrile-butadiene rubber being particularly preferred. Two or more of these may be used in combination.

[0027] 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 combined amount of vinyl chloride resin and elastic resin. If the amount 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 the amount exceeds 16% by mass, foaming characteristics deteriorate, rubber-like properties become dominant, and stress relaxation deteriorates, resulting in embossing return during embossing and poor transferability of the embossed pattern. The elastic resin is contained preferably 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 combined amount of vinyl chloride resin and elastic resin.

[0028] (plasticizer) As the plasticizer in the present invention, any known plasticizer can be used.

[0029] In the present invention, for example, phthalic acid derivatives such as dibutyl phthalate, di-(2-ethylhexyl) phthalate, di-n-octyl phthalate, diisobutyl phthalate, diheptyl phthalate, diphenyl phthalate, diisodecyl phthalate, diundecyl phthalate, butyl benzyl phthalate, dinonyl phthalate, and dicyclohexyl phthalate; isophthalic acid derivatives such as di-(2-ethylhexyl) isophthalate, diisooctyl isophthalate, and diisononyl phthalate; di-(2-ethylhexyl) tetrahydrophthalate, di-n- Tetrahydrophthalic acid derivatives such as octyl tetrahydrophthalate and diisodecyl tetrahydrophthalate; adipic acid derivatives such as di-n-butyl adipate, di-(2-ethylhexyl) adipate, diisodecyl adipate and diisononyl adipate; azelaic acid derivatives such as di-(2-ethylhexyl) azelate, diisooctyl 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 di-(2-ethylhexyl) maleate; fumaric acid derivatives such as di-n-butyl fumarate, di-(2-ethylhexyl) fumarate; trimellitic acid derivatives such as tri-(2-ethylhexyl) trimellitate, tri-n-octyl trimellitate, triisodecyl trimellitate, triisooctyl trimellitate, tri-n-hexyl trimellitate, triisononyl trimellitate; pyromellitic acid derivatives such as tetra-(2-ethylhexyl) pyromellitate, tetra-n-octyl pyromellitate; triethyl citrate citric acid derivatives such as monomethyl itaconate, monobutyl itaconate, dimethyl itaconate, diethyl itaconate, dibutyl itaconate, di-(2-ethylhexyl) itaconate; oleic acid derivatives such as butyl oleate, glyceryl monooleate, diethylene glycol monooleate; ricinoleic acid derivatives such as glyceryl monoricinoleate, diethylene glycol monoricinoleate;Stearic acid derivatives such as glycerin monostearate and diethylene glycol distearate; other fatty acid derivatives such as diethylene glycol monolaurate, diethylene glycol dipelargonate, and pentaerythritol fatty acid esters; phosphoric acid derivatives such as triethyl phosphate, tributyl phosphate, tri-(2-ethylhexyl) phosphate, triphenyl phosphate, cresyl diphenyl phosphate, tricresyl phosphate, and tris(chloroethyl) phosphate; glycol derivatives such as diethylene glycol dibenzoate, dipropylene glycol dibenzoate, triethylene glycol dibenzoate, and dibutylmethylene bisthioglycolate; glycerin derivatives such as glycerol monoacetate, glycerol triacetate, and glycerol tributyrate; polyester plasticizers such as adipic acid polyesters, sebacic acid polyesters, and phthalic acid polyesters; or partially hydrogenated terphenyls, adhesive plasticizers; and even polymerizable plasticizers such as diallyl phthalate, acrylic monomers, and oligomers. Two or more of these plasticizers may be used in combination.

[0030] (Other ingredients) The foamed vinyl chloride resin sheet of the present invention may contain various other components in addition to the vinyl chloride resin, elastic resin, and plasticizer, such as a heat stabilizer, a filler, a foaming accelerator, a viscosity modifier, an adhesion promoter, a colorant, a diluent, an ultraviolet absorber, an antioxidant, and a reinforcing agent.

[0031] The foamed vinyl chloride resin sheet of the present invention is flexible and can be used as a foamed resin layer for, for example, wall materials, floor materials, book covers, leather, and the like.

[0032] [Method of manufacturing foamed polyvinyl chloride resin sheets] The method for producing a foamed vinyl chloride resin sheet of the present invention involves kneading a vinyl chloride resin, an elastic resin having an SP value of 7.5 to 11.0, and a plasticizer, molding the resulting kneaded mixture into a sheet, and then foaming the resulting sheet. This production method allows the production of the foamed vinyl chloride resin sheet of the present invention.

[0033] In the manufacturing method of the present invention, as described above, a raw material 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, but other components may also be blended. For example, it is preferable to use a foaming agent in addition to the other components exemplified above.

[0034] Examples of the foaming agent include inorganic foaming agents such as sodium bicarbonate, ammonium bicarbonate, ammonium nitrite, amide compounds, and sodium borohydride; and organic foaming agents such as isocyanate compounds, azo compounds, hydrazine derivatives, semicarbazide compounds, azide compounds, nitroso compounds, and triazole compounds, and two or more of these may be used in combination.

[0035] In the manufacturing method of the present invention, it is not always necessary to use a foaming agent, and examples thereof include the use of microcapsules, a volatile liquid, and mechanical foaming.

[0036] Examples of sheet molding methods include calendar molding, extrusion molding, and inflation molding. Calendar molding is preferred because it allows efficient sheet molding and effectively demonstrates the effects of the present invention. In calendar molding, it is preferred to first charge a composition containing a vinyl chloride resin and a plasticizer into the device, and then add the elastic resin during sheet molding. The heating temperature during sheet molding is not particularly limited as long as it melts the raw vinyl chloride composition and does not cause the foaming agent to decompose and foam, and is, for example, 110 to 230°C, and preferably 140 to 170°C.

[0037] 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 is a temperature at which the foaming agent decomposes, and is, for example, 110 to 230°C, preferably 180 to 210°C. [Example]

[0038] EXAMPLES The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0039] [Example 1] A vinyl chloride composition (compound) was prepared by mixing 99 parts by mass of a suspension vinyl chloride resin with a viscosity-average degree of polymerization of 1020 (ZEST 1000Z, manufactured by Shin-Dai-Ichi Vinyl Corporation) as the vinyl chloride resin, 58 parts by mass of di-(2-ethylhexyl) phthalate (DOP, manufactured by J-Plus Corporation) as the plasticizer, 15 parts by mass of calcium carbonate, 2.5 parts by mass of Cellmike C-2, manufactured by Sankyo Kasei Co., Ltd., as the foaming agent, 3 parts by mass of SC-320, manufactured by ADEKA Corporation, as the stabilizer, and 1 part by mass of Metablen P-530A, manufactured by Mitsubishi Chemical Corporation, at 3,000 rpm in a Henschel mixer (UM2E / I, manufactured by Nippon Coke and Engineering Co., Ltd.) until the resin temperature rose to 120°C.

[0040] The prepared vinyl chloride composition was placed in a calendar molding machine, and 1 part by mass of acrylonitrile-butadiene rubber (NBR) was added as an elastic resin during sheet molding. The resulting sheet was heated to foam, producing a foamed vinyl chloride resin sheet according to Example 1.

[0041] [Example 2] A foamed vinyl chloride resin sheet according to Example 2 was produced in the same manner as in Example 1, except that the amount of vinyl chloride resin blended was changed from 99 parts by mass to 95 parts by mass, and the amount of elastic resin blended was changed from 1 part by mass to 5 parts by mass. [Example 3] A foamed vinyl chloride resin sheet according to Example 3 was produced in the same manner as in Example 1, except that the amount of vinyl chloride resin blended was changed from 99 parts by mass to 90 parts by mass, and the amount of elastic resin blended was changed from 1 part by mass to 10 parts by mass. [Example 4] A foamed vinyl chloride resin sheet according to Example 4 was produced in the same manner as in Example 1, except that the amount of vinyl chloride resin blended was changed from 99 parts by mass to 85 parts by mass, and the amount of elastic resin blended was changed from 1 part by mass to 15 parts by mass.

[0042] [Comparative Example 1] A foamed vinyl chloride resin sheet according to Comparative Example 1 was produced in the same manner as in Example 1, except that the amount of vinyl chloride resin blended was changed from 99 parts by mass to 100 parts by mass, and the amount of elastic resin blended was changed from 1 part by mass to 0 part by mass (no blending). Comparative Example 2 A foamed vinyl chloride resin sheet according to Comparative Example 2 was produced in the same manner as in Example 1, except that the amount of vinyl chloride resin blended was changed from 99 parts by mass to 80 parts by mass, and the amount of elastic resin blended was changed from 1 part by mass to 20 parts by mass.

[0043] [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 degree of polymerization of 1020 was changed to a vinyl chloride resin having a viscosity average degree of polymerization 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 degree of polymerization of 1020 was changed to a vinyl chloride resin having a viscosity average degree of polymerization of 810.

[0044] [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 degree of polymerization of 1020 was changed to a vinyl chloride resin having a viscosity average degree of polymerization 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 degree of polymerization of 1020 was changed to a vinyl chloride resin having a viscosity average degree of polymerization of 1740.

[0045] Comparative Example 3 A foamed vinyl chloride resin sheet according to Comparative Example 3 was produced in the same manner as in Example 5, except that the amount of vinyl chloride resin blended was changed from 95 parts by mass to 100 parts by mass, and the amount of elastic resin blended was changed from 5 parts by mass to 0 parts by mass (no blending). Comparative Example 4 A foamed vinyl chloride resin sheet according to Comparative Example 4 was produced in the same manner as in Example 6, except that the amount of vinyl chloride resin blended was changed from 95 parts by mass to 100 parts by mass, and the amount of elastic resin blended was changed from 5 parts by mass to 0 parts by mass (no blending).

[0046] Comparative Example 5 A foamed vinyl chloride resin sheet according to Comparative Example 5 was produced in the same manner as in Example 7, except that the amount of vinyl chloride resin blended was changed from 95 parts by mass to 100 parts by mass, and the amount of elastic resin blended was changed from 5 parts by mass to 0 parts by mass (no blending). Comparative Example 6 A foamed vinyl chloride resin sheet according to Comparative Example 6 was produced in the same manner as in Example 8, except that the amount of vinyl chloride resin blended was changed from 95 parts by mass to 100 parts by mass, and the amount of elastic resin blended was changed from 5 parts by mass to 0 parts by mass (no blending).

[0047] [Example 9] A foamed polyvinyl chloride resin sheet according to Example 9 was produced in the same manner as in Example 2, except that the elastic resin, acrylonitrile butadiene rubber (NBR), was changed to thermoplastic polyurethane (SBR). [Example 10] A foamed polyvinyl chloride resin sheet according to Example 10 was produced in the same manner as in Example 2, except that the elastic resin, acrylonitrile butadiene rubber (NBR), was replaced with an elastic resin, thermoplastic polyurethane (TPU). [Example 11] A foamed polyvinyl chloride resin sheet according to Example 11 was produced in the same manner as in Example 2, except that the elastic resin, acrylonitrile butadiene rubber (NBR), was changed to an elastic resin, chloroprene rubber (CR).

[0048] [Example 12] A foamed polyvinyl chloride resin sheet according to Example 12 was produced in the same manner as in Example 2, except that the elastic resin, acrylonitrile butadiene rubber (NBR), was replaced with an elastic resin, chlorosulfonated polyethylene (CSM). [Example 13] A foamed polyvinyl chloride resin sheet according to Example 13 was produced in the same manner as in Example 2, except that the elastic resin, acrylonitrile butadiene rubber (NBR), was replaced with an elastic resin, acrylic rubber (ACM). [Example 14] A foamed polyvinyl chloride resin sheet according to Example 14 was produced in the same manner as in Example 2, except that the elastic resin, acrylonitrile butadiene rubber (NBR), was replaced with an elastic resin, chlorinated polyethylene (CPE).

[0049] Comparative Example 7 A foamed polyvinyl chloride resin sheet according to Comparative Example 7 was produced in the same manner as in Example 2, except that the elastic resin, acrylonitrile butadiene rubber (NBR), was replaced with fluororubber (FKM), an elastic resin whose SP value falls outside the range of the present invention.

[0050] 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, residual stress, foam cell density, surface smoothness, and expansion ratio by the following methods.

[0051] (Tensile test sample) Ten No. 1 dumbbell-shaped tensile test pieces were prepared from each foamed polyvinyl chloride resin sheet in the calender roll direction (MD) to serve as samples for the tensile test.

[0052] (tensile elongation, tensile strength, residual stress rate) The tensile elongation, tensile strength, and residual stress rate of the tensile test sample were measured using an autograph (AGS-H manufactured by Shimadzu Corporation). In the tensile test, the sample was pulled at a grip distance of 40 mm and a test speed of 3 mm / min, and the elongation at which the foamed polyvinyl chloride resin sheet began to break was divided by the grip distance to obtain the elongation rate. The maximum stress before the foamed polyvinyl chloride resin sheet began to break was taken as the tensile strength, and the average value of n=5 was calculated. The residual stress rate was measured by pulling the sample at a test speed of 40 mm / min until the grip distance was changed from 40 mm to 60 mm, and the stress immediately after that was taken as the initial stress σ0, and the stress after 600 seconds was taken as σ. t and residual stress rate = (σ t / σ0) × 100, and the average value of n = 5 was calculated.

[0053] (Evaluation of foam cell density) The cross section of the foamed polyvinyl chloride resin sheet was observed at 50x magnification with a CCD camera, and the density of the foam cells was evaluated according to the following criteria.

[0054] ◯: Extremely dense and uniform foam cells. Δ: Somewhat coarse or uneven foam cells are present. ×: Coarse foam cells are present.

[0055] (Surface smoothness) The surface was visually observed and the surface layer of the cross section was observed under magnification, and the results were evaluated according to the following criteria. 〇: The entire surface is smooth △: Mostly smooth, but some unevenness ×: There is uneven swelling or unevenness throughout the surface

[0056] (Expansion ratio) The thickness was measured at any five points on the calender-molded sheet produced above, and the average value was designated as the thickness before foaming, L0. The thickness of the foamed vinyl chloride resin sheet obtained by heat foaming was also measured at the same five points as the thickness of the calender-molded sheet, and the average value was designated as the thickness after foaming, L, and the foaming ratio was calculated as L / L0.

[0057] The results are shown in Tables 1 to 3.

[0058] [Table 1]

[0059] [Table 2]

[0060] [Table 3]

[0061] As shown in Tables 1 to 3, the foamed vinyl chloride resin sheets of Examples 1 to 14 were excellent in tensile elongation, tensile strength, and residual stress (stress relaxation), and also had high expansion ratios, foam cell density, and surface smoothness. In other words, foamed vinyl chloride resin sheets with excellent mechanical properties and foaming characteristics were obtained. As shown in Table 2, the use of a vinyl chloride resin with a high degree of polymerization generally tends to improve tensile elongation and tensile strength, but these properties are further improved by incorporating an elastic resin. Furthermore, as shown in Table 3, compared with Example 12 (CSM) and Example 13 (ACM), Examples 1 (NBR), 9 (SBR), 10 (TPU), 11 (CR), and 14 (CPE), which used other elastic resins, had better elongation. This is presumably because, in the case of Example 12 (CSM) and Example 13 (ACM), the resin became slightly hard and exhibited some brittleness.

[0062] On the other hand, as shown in Table 1, even if the elastic resin is appropriate, if the blending amount is too large, as in Comparative Example 2, the residual stress rate increases, the embossing properties decrease, and the foaming properties also deteriorate. Also, as shown in Table 3, with an elastic resin whose SP value is outside the range of the present invention, as in Comparative Example 7, the residual stress rate improves and the foaming properties also deteriorate, although no improvement in tensile elongation or tensile strength is observed. [Industrial Applicability]

[0063] The foamed vinyl chloride resin sheet of the present invention can be used as a foamed resin layer for wallpaper and the like, and is therefore industrially useful.

Claims

1. The adhesive contains a homopolymer of vinyl chloride, an elastic resin that is a butadiene-based rubber, and a plasticizer, The foamed vinyl chloride resin sheet is characterized in that the elastic resin is contained in an amount of 1 to 10 parts by mass per 100 parts by mass of the total amount of the vinyl chloride homopolymer and the elastic resin.

2. 2. The foamed vinyl chloride resin sheet according to claim 1, wherein the viscosity-average degree of polymerization of the vinyl chloride homopolymer is 450 to 1,800.

3. A method for producing the foamed vinyl chloride resin sheet according to claim 1 or 2, comprising: A method for producing a foamed vinyl chloride resin sheet, comprising kneading a vinyl chloride homopolymer, an elastic resin which is a butadiene-based rubber, and a plasticizer, molding the resulting kneaded mixture into a sheet, and then foaming the resulting sheet.

4. 4. The method for producing a foamed polyvinyl chloride resin sheet according to claim 3, wherein the sheet molding is calender molding.

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