Method for producing rubber composition

Abstract

To provide a method in which the outcome of blending vinyl chloride resin into nitrile rubber is more effectively achieved.SOLUTION: Provided is a method for producing a rubber composition in which a plasticizer-carrying porous vinyl chloride-based resin powder, which is obtained by mixing a porous vinyl chloride-based resin powder by 100 pts.mass and a plasticizer by 5 to 20 pts.mass to have the plasticizer carried in the pores of the porous vinyl chloride-based resin powder, and a nitrile rubber by 100 to 900 pts.mass are added and kneaded.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing a rubber composition using a nitrile rubber and a vinyl chloride resin. [Background technology]

[0002] Nitrile rubber is known as a material having excellent oil resistance and chemical resistance, and is used, for example, as a material for vehicle parts such as fuel packings, timing belts, and hoses.

[0003] Various studies and proposals have been made on such nitrile rubber with the aim of improving its performance and increasing its usefulness. For example, it has been proposed to laminate a vinyl chloride resin layer on a nitrile rubber layer (see Patent Document 1) or to blend a vinyl chloride resin into nitrile rubber (see Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-269576 A [Patent Document 2] WO2012 / 105645 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, attempts have been made to improve the performance of nitrile rubber by using vinyl chloride resins, but the characteristics of vinyl chloride resins have not necessarily been fully utilized.

[0006] An object of the present invention is to provide a method for more effectively utilizing the effect of blending a vinyl chloride resin with a nitrile rubber. [Means for solving the problem]

[0007] The present inventors, while conducting intensive research into improving the performance of rubber compositions using nitrile rubber and vinyl chloride resin, have found that the above-mentioned problems can be solved by using porous vinyl chloride resin powder as the vinyl chloride resin, carrying a predetermined amount of plasticizer in the pores of the porous vinyl chloride resin powder, and kneading the same with nitrile rubber, and have thus completed the present invention.

[0008] That is, in the past, nitrile rubber, vinyl chloride resin, and plasticizer were added separately and kneaded together, but it was discovered that by supporting a predetermined amount of plasticizer in the pores of porous vinyl chloride resin powder and kneading the mixture, the blending effect of the vinyl chloride resin can be more effectively enjoyed.

[0009] That is, the present invention is as follows. [1] A method for producing a rubber composition, comprising kneading a plasticizer-supported porous polyvinyl chloride resin powder obtained by mixing 100 parts by mass of a porous polyvinyl chloride resin powder and 5 to 20 parts by mass of a plasticizer to support the plasticizer in the pores of the porous polyvinyl chloride resin powder with 100 to 900 parts by mass of nitrile rubber. [2] A method for producing a rubber composition according to the above [1], characterized in that an additional plasticizer is added and kneaded in addition to the supported plasticizer in the plasticizer-supported porous polyvinyl chloride resin powder. [3] The method for producing a rubber composition according to the above [2], wherein the total amount of the supported plasticizer and the additional plasticizer is 10 to 50 parts by mass.

[0010] [4] The pore volume of the porous polyvinyl chloride resin powder is 0.09 to 0.45 cm 3 / g. [5] The method for producing a rubber composition according to any one of the above [1] to [4], wherein the supported plasticizer is a polyester-based plasticizer. [6] The method for producing a rubber composition according to the above [5], wherein the polyester plasticizer has an average molecular weight of 400 to 3,000 and an SP value of 8.5 to 9.5. Effect of the Invention

[0011] According to the present invention, it is possible to produce a rubber composition which more effectively utilizes the effects of blending a vinyl chloride resin, such as improved ozone resistance and heat aging resistance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The method for producing a rubber composition of the present invention is characterized in that a plasticizer-supported porous polyvinyl chloride resin powder obtained by mixing 100 parts by mass of a porous polyvinyl chloride resin powder and 5 to 20 parts by mass of a plasticizer so as to support the plasticizer in the pores of the porous polyvinyl chloride resin powder is kneaded with 100 to 900 parts by mass of nitrile rubber.

[0013] In the present invention, the plasticizer-supported porous polyvinyl chloride resin powder, in which a predetermined amount of plasticizer is supported in the pores, is kneaded with the nitrile rubber, so that the nitrile rubber and the polyvinyl chloride resin are easily compatible (alloyed), and the blending effect of the polyvinyl chloride resin can be more effectively enjoyed. Therefore, the rubber composition produced is superior in ozone resistance, heat aging resistance, oil resistance, elongation, etc., compared to those produced by simply adding a plasticizer.

[0014] The excellent physical properties of the rubber composition as described above are believed to be exhibited by the expression of the mobility of polyvinyl chloride at the molecular level due to the gelation and melting of the vinyl chloride resin caused by the heat during kneading, and the phenomenon of compatibility with the nitrile rubber at the molecular level caused by kneading with an appropriate shear stress. Specifically, when kneaded with nitrile rubber, the porous polyvinyl chloride resin powder disintegrates into primary particles of grain particles, then the primary particles melt and disintegrate, and further disintegrates to the stage of domains, which is the final stage of molecular mobility expression, but since a predetermined amount of plasticizer is supported in the pores, the disintegration into primary particles proceeds smoothly, and the disintegration proceeds easily to the subsequent domains, as a result, compatibilization becomes easy, and the properties of the polyvinyl chloride resin can be fully enjoyed. In addition, since compatibilization at low temperatures is possible, the deterioration (decrease in physical properties) of the polyvinyl chloride resin due to heat can be suppressed, and this also allows the properties of the polyvinyl chloride resin to be fully enjoyed.

[0015] In addition, when vinyl chloride resin powder having no internal pores, such as vinyl chloride resin powder for so-called paste processing, is kneaded with nitrile rubber and a plasticizer, it is difficult to obtain the effect of the plasticizer in improving particle disintegration, so that disintegration down to the domains of the vinyl chloride resin powder hardly occurs, and furthermore, the melt viscosity is difficult to increase to the required shear stress, so that compatibilization does not proceed sufficiently.

[0016] The rubber composition produced by the production method of the present invention can be used for the same applications as ordinary nitrile rubber, for example, as a material for vehicle parts such as fuel packing, timing belts, and hoses, and industrial parts.

[0017] (Porous polyvinyl chloride resin powder) The porous vinyl chloride resin in the present invention is a vinyl chloride resin consisting of porous irregular particles obtained mainly by suspension polymerization, and is also called a general-purpose vinyl chloride resin. Porous vinyl chloride resins include homopolymers of vinyl chloride as well as copolymers mainly made of vinyl chloride. Mainly made of vinyl chloride means that, for example, vinyl chloride accounts for 50% by mass or more of the total, preferably 70% by mass or more, and more preferably 90% by mass or more.

[0018] Examples of monomers that can be copolymerized 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 acrylate, ethyl acrylate, n-butyl acrylate, 2-hydroxyethyl acrylate, methyl methacrylate, ethyl methacrylate, and N,N-dimethylaminoethyl methacrylate; unsaturated amides such as acrylamide and methacrylamide; unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated dicarboxylic acids such as maleic acid and fumaric acid; esters and anhydrides thereof; N-substituted maleimides; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; and vinylidene compounds such as vinylidene chloride.

[0019] The porous vinyl chloride resin of the present invention can be obtained by polymerizing vinyl chloride alone or a monomer mixture consisting of vinyl chloride and an unsaturated monomer copolymerizable therewith by a conventionally known method. For example, it can be obtained by suspension polymerization. By appropriately setting various reaction conditions such as temperature, type and amount of dispersant, stirring speed, etc., a resin with the desired particle size, pore volume (porosity), and polymerization degree can be obtained.

[0020] The porous polyvinyl chloride resin is generally in the form of particles having an average particle diameter (D50) of about 50 to 200 μm. The average particle diameter (D50) is preferably 70 to 180 μm, and more preferably 100 to 150 μm. This average particle size (D50) is shown as the 50% passing diameter using a JIS Z8801 sieve according to JIS Z8815 (dry sieving test method).

[0021] The pore volume of porous polyvinyl chloride resin is 0.09 to 0.45 cm 3 / g, and 0.15 to 0.45 cm 3 / g, and more preferably 0.20 to 0.40 cm 3 / g is more preferable. By having a pore volume in this range, a desired amount of plasticizer can be easily and appropriately supported. Therefore, when kneading with the nitrile rubber, particle collapse to the domain of the vinyl chloride resin is easily and reliably performed, and compatibilization proceeds more effectively. The porosity can be determined by mercury intrusion method (porosimeter).

[0022] The average degree of polymerization of the porous vinyl chloride resin is preferably 600 to 1700, more preferably 700 to 1500, and further preferably 800 to 1300. By having the average degree of polymerization within this range, it is possible to obtain a rubber composition having excellent compatibility with nitrile rubber without impairing the physical properties of the rubber composition. This average degree of polymerization is calculated by converting the reduced viscosity (K value) measured in accordance with the vinyl chloride resin testing method (published by the PVC Industry and Environment Association in April 2003) in accordance with JIS K7367-2 using the approximate formula: K value = 20.42 * Ln (degree of polymerization) - 74.93.

[0023] (Nitrile rubber) The nitrile rubber of the present invention is a rubber having a structural unit having a nitrile group, specifically, a copolymer of a nitrile such as acrylonitrile or methacrylonitrile, and a conjugated diene such as 1,3-butadiene or isoprene.

[0024] More specifically, examples of the nitrile rubber of the present invention include acrylonitrile butadiene rubber (NBR), acrylonitrile butadiene isoprene rubber (NBIR), and acrylonitrile isoprene rubber (NBI).

[0025] Furthermore, the nitrile rubber may contain, in addition to the nitrile and conjugated diene, units of other monomers copolymerizable with these monomers. The nitrile and conjugated diene preferably account for 70% by mass or more of the total, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0026] The amount of the nitrile rubber is 100 to 900 parts by mass (per 100 parts by mass of the porous polyvinyl chloride resin) as described above, but is preferably 150 to 600 parts by mass, and more preferably 200 to 500 parts by mass. By using the amount in this range, it is possible to obtain a more well-balanced rubber composition that utilizes the characteristics of the nitrile rubber while imparting the characteristics of the polyvinyl chloride resin.

[0027] (Plasticizer) As the plasticizer supported in the pores of the porous polyvinyl chloride resin powder (supported plasticizer), any of the conventionally known plasticizers used in blends of nitrile rubber and polyvinyl chloride resin can be used.

[0028] 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-n-butyl fumarate and di-(2-ethylhexyl) fumarate; fumaric acid derivatives such as di-(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 and 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 dibutyl methylene 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 and adhesive plasticizers; and further, polymerizable plasticizers such as diallyl phthalate and acrylic monomers and oligomers can be used. These plasticizers may be used alone or in combination of two or more.

[0029] Among these, polyester plasticizers are preferred from the viewpoints of compatibility with vinyl chloride resins, swelling properties, etc. The average molecular weight (number average molecular weight) of the polyester plasticizer is preferably about 400 to 3000, more preferably about 700 to 3000, and even more preferably about 1500 to 2500. The SP value (solubility parameter) of the polyester plasticizer is preferably 8.5 to 9.5, and more preferably 9.2 to 9.5.

[0030] The amount of the plasticizer (supported plasticizer) supported on the porous polyvinyl chloride resin powder is 5 to 20 parts by mass, preferably 10 to 20 parts by mass, per 100 parts by mass of the porous polyvinyl chloride resin powder. If the amount of the plasticizer is less than 5 parts by mass, the effect of the plasticizer in expressing the particle disintegration property of the porous polyvinyl chloride resin is not exhibited. On the other hand, if the amount exceeds 20 parts by mass, the viscosity during shearing becomes too low, so that the particle disintegration property of the porous polyvinyl chloride resin is deteriorated, and the melt viscosity becomes too low, so that the shear stress becomes too low, so that the compatibility (polymer alloying) of both resins is delayed and does not proceed sufficiently, and the inherent excellent alloy properties are not exhibited.

[0031] In the present invention, the compatibility of both resins is sufficiently advanced without adding any other plasticizer than the supported plasticizer, and the properties of the vinyl chloride resin can be effectively imparted to the nitrile rubber. In addition, by supporting the plasticizer in the pores, the total amount of plasticizer used can be reduced.

[0032] In the present invention, in order to further improve the compatibility with nitrile rubber, it is preferable to blend an additional plasticizer in addition to the supported plasticizer. In this case, the supported plasticizer mainly contributes to the collapse of the grain domain of the porous polyvinyl chloride resin powder, and the additional plasticizer mainly contributes to the adjustment of the shear force and the compatibilization in the compatibilization process with the nitrile rubber. The additional plasticizer is preferably blended so that the total amount of the supported plasticizer and the additional plasticizer is 10 to 50 parts by mass (per 100 parts by mass of the porous polyvinyl chloride resin), more preferably 10 to 40 parts by mass, and even more preferably 20 to 40 parts by mass. If the total amount of the supported plasticizer and the additional plasticizer exceeds 50 parts by mass, an appropriate shear force is not generated, and appropriate compatibilization may be difficult. The type of the additional plasticizer can be the same as that of the supported plasticizer. The supported plasticizer and the additional plasticizer may be the same or different.

[0033] (Method of Supporting Plasticizer on Porous Polyvinyl Chloride Resin Powder) The plasticizer-supported porous polyvinyl chloride resin powder can be obtained by mixing 100 parts by mass of the porous polyvinyl chloride resin powder and 5 to 20 parts by mass of the plasticizer in a mixer under heating. Examples of the mixer include a Henschel mixer, a planetary mixer, and a ribbon mixer. The temperature of the mixer is increased while adding the plasticizer and stirring, and the mixing temperature is preferably 50 to 130°C, more preferably 80 to 100°C. When the plasticizer is supported, the plasticizer may be dissolved in an organic solvent and mixed with the porous polyvinyl chloride resin powder. The organic solvent may be removed by evaporation during and / or after the support.

[0034] Furthermore, in addition to the above-mentioned plasticizer, the plasticizer-supported porous polyvinyl chloride resin powder may also support additives other than the plasticizer, such as heat stabilizers, antioxidants, UV absorbers, viscosity modifiers, diluents, colorants, etc., to the extent that the effects of the present invention are not adversely affected. The amount of these additives supported is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of the porous polyvinyl chloride resin powder.

[0035] (Method of kneading plasticizer-supported porous polyvinyl chloride resin powder with nitrile rubber) In the present invention, 105 to 120 parts by mass of plasticizer-supported vinyl chloride resin powder (including 5 to 20 parts by mass of plasticizer), 100 to 900 parts by mass of nitrile rubber, and additional plasticizer as necessary are added and kneaded using a kneading device. In addition to these components, the above-mentioned compounding agents such as heat stabilizers and antioxidants may be added within a range that does not affect the effects of the present invention.

[0036] The kneading device is not particularly limited as long as it can sufficiently knead both resins, and a conventionally known device can be used, for example, a Brambender mixer, a Banbury mixer, a Henschel mixer, a single screw extruder, a twin screw extruder, a mixing roll, a pressure kneader, etc. In the present invention, compatibility can be achieved at a relatively low temperature, and the kneading temperature is, for example, preferably about 100 to 200°C, more preferably about 120 to 180°C. EXAMPLES

[0037] 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.

[0038] [Example 1] <Supporting plasticizer in the internal pores of porous polyvinyl chloride resin powder> A 2L Henschel mixer (Mitsui Miike Works Ltd.) was charged with porous polyvinyl chloride resin powder (ZEST 1700ZI (Shin Daiichi Vinyl Co., Ltd.) with an internal pore volume of 0.37 cm 3 While stirring at 1000 rpm, 50 g of polyester plasticizer D645 (J-Plus Corporation, average molecular weight 2200) was added, and the jacket was heated to 90°C and then cooled to room temperature to prepare a plasticizer-supported porous polyvinyl chloride resin powder.

[0039] <Production of Rubber Composition (Roll Sheet)> 100 g of the plasticizer-loaded porous polyvinyl chloride resin powder prepared above, 300 g of NBR (acrylonitrile butadiene rubber, JSR N230SL) that had been crushed in advance to a diameter of 4 mm or less using a grinder, and 20 g of polyester-based plasticizer D645 were lightly mixed in a stainless steel bowl, and then the mixture was gathered together and kneaded for 7 minutes on an 8-inch roll heated to 150°C to obtain a roll sheet.

[0040] <Preparation of samples for evaluating physical properties> The obtained roll sheet was sandwiched between stainless steel plates containing a 2 mm thick stainless steel spacer, set in a press heated to 150°C, and pressed at a pressure of 100 kPa for 6 minutes to obtain a rubber molded product having a thickness of 2.0 mm.

[0041] [Example 2] The same procedure as in Example 1 was carried out, except that the polyester plasticizer added during roll kneading was not used.

[0042] [Example 3] The same procedure as in Example 1 was carried out, except that 20 parts by mass of polyester-based plasticizer was supported on the porous polyvinyl chloride resin powder and no polyester-based plasticizer was mixed during roll kneading.

[0043] [Example 4] The same procedure as in Example 1 was repeated, except that the amount of polyester-based plasticizer supported on the porous polyvinyl chloride resin powder was changed to 20 parts by mass, and the amount of polyester-based plasticizer mixed during roll kneading was changed to 10 parts by mass.

[0044] [Example 5] Example 1 was repeated, except that the amount of polyester plasticizer supported on the porous polyvinyl chloride resin powder was changed to 20 parts by mass.

[0045] [Example 6] In Example 1, the porous polyvinyl chloride resin powder to support the plasticizer was ZEST 1000Z (Shin-Daiichi Vinyl Corporation, pore volume 0.27 cm 3 The procedure of Example 1 was repeated except that the concentration of 100 mg / g was changed to 100 mg / g.

[0046] [Example 7] In Example 1, the porous polyvinyl chloride resin powder to support the plasticizer was ZEST 700L (Shin-Daiichi Vinyl Corporation, pore volume 0.09 cm 3 The procedure of Example 1 was repeated except that the concentration of 100 mg / g was changed to 100 mg / g.

[0047] [Example 8] Example 1 was repeated, except that the amount of nitrile rubber was changed to 600 parts by mass per 100 parts by mass of the porous polyvinyl chloride resin powder.

[0048] [Example 9] Example 1 was repeated, except that the amount of nitrile rubber was changed to 150 parts by mass per 100 parts by mass of the porous polyvinyl chloride resin powder.

[0049] [Example 10] The same procedure as in Example 1 was repeated, except that the plasticizer used for supporting the porous polyvinyl chloride resin powder and for mixing during roll kneading was changed to D620 (manufactured by J-Plus Corporation, polyester type, average molecular weight 800).

[0050] [Example 11] The same procedure as in Example 1 was repeated, except that the roll kneading and press temperature was changed to 130°C.

[0051] [Example 12] The same procedure as in Example 1 was repeated, except that the plasticizer used for supporting the porous polyvinyl chloride resin powder and for mixing during roll kneading was changed to diisononyl phthalate (DINP, manufactured by J-Plus Corporation).

[0052] [Comparative Example 1] The same procedure as in Example 1 was repeated except that the porous polyvinyl chloride resin powder was used without supporting a polyester-based plasticizer, and furthermore, no polyester-based plasticizer was added during roll kneading.

[0053] [Comparative Example 2] The same procedure as in Example 1 was repeated, except that the porous polyvinyl chloride resin powder was used without supporting a polyester-based plasticizer, and the amount of polyester-based plasticizer added during roll kneading was changed to 30 parts by mass.

[0054] [Comparative Example 3] The same procedure as in Example 1 was repeated, except that the amount of polyester-based plasticizer supported on the porous polyvinyl chloride resin powder was changed to 25 parts by mass, and the amount of polyester-based plasticizer mixed during roll kneading was changed to 15 parts by mass.

[0055] [Comparative Example 4] The same procedure as in Example 1 was repeated, except that the amount of polyester-based plasticizer supported on the porous polyvinyl chloride resin powder was changed to 30 parts by mass, and the amount of polyester-based plasticizer mixed during roll kneading was changed to 10 parts by mass.

[0056] [Comparative Example 5] Example 1 was repeated, except that the amount of nitrile rubber was changed to 50 parts by mass per 100 parts by mass of the porous polyvinyl chloride resin powder.

[0057] [Comparative Example 6] The same procedure as in Comparative Example 1 was carried out, except that the roll kneading and press temperature was changed to 130°C.

[0058] The rubber compositions (molded rubber articles) according to Examples 1 to 12 and Comparative Examples 1 to 6 were evaluated as follows.

[0059] <Ozone resistance> According to the static ozone deterioration test method A of the ozone resistance test (JIS K6259-1), a 10 mm wide rectangular test piece was taken from the obtained rubber molded product, and after applying 20% ​​tension and treating it with an ozone weather meter at 40°C and an ozone concentration of 500 ppb for 72 hours, the sample was taken out and observed for cracks and ranked according to the following prescribed method. Those with no visible cracks were rated as ◯.

[0060] (Ranking by number of cracks) A: Few cracks B: Many cracks C: Countless cracks

[0061] (Ranking based on crack size and depth) 1: Something that cannot be seen with the naked eye but can be seen with a 10x magnifying glass. 2: Visible to the naked eye. 3: The crack is deep and relatively large (less than 1 mm). 4: The crack is deep and large (1mm or more but less than 3mm). 5: Likely to cause cracks or cuts of 3 mm or more.

[0062] <Oil resistance> According to the oil resistance test (JIS K6258), a 30 mm square test piece was taken from the obtained rubber molded product, and the volume change rate was determined before and after immersion in test oil IRM903 at 100° C. for 72 hours.

[0063] The volume expansion rate (%) was evaluated as follows: 0 to +10% was rated as ◎, +10 to +15% was rated as 〇, +15 to +20% was △, and +20% or more was rated as ×.

[0064] <Tensile test (elongation)> According to the tensile test (JIS K6251), dumbbell-shaped No. 2 test pieces were taken from the obtained rubber molded products, and the elongation at break was evaluated using an autograph at a test speed of 200 mm / min.

[0065] The breaking elongation (%) was evaluated as follows: >300% was rated as ◎, 250-300% was rated as ◯, 200-250% was △, and <200% was rated as ×.

[0066] <Heat aging resistance> The dumbbell-shaped No. 2 test pieces were subjected to an accelerated heat aging test (JIS K6257) at 100°C for 72 hours, and then the elongation at break was evaluated using an autograph at a test speed of 200 mm / min.

[0067] The reduction rate (%) of breaking elongation after the heat aging test was evaluated as follows: <10% = ◎, 10-15% = ◯, 15-20% = △, and >20% = ×.

[0068] The results are shown in Tables 1 to 3.

[0069] [Table 1]

[0070] [Table 2]

[0071] [Table 3]

[0072] As shown in Tables 1 and 2, the rubber compositions using the plasticizer-supported porous polyvinyl chloride resin powders of Examples 1 to 12, in which a plasticizer was supported in the pores, had excellent ozone resistance, oil resistance, elongation, and heat aging resistance.

[0073] On the other hand, as shown in Table 3, in Comparative Examples 1 to 6 which do not satisfy the requirements of the present invention, such as those which do not support a plasticizer or those which have an inappropriate amount of plasticizer, satisfactory performance was not obtained in terms of ozone resistance, oil resistance, elongation, and heat aging resistance. [Industrial Applicability]

[0074] INDUSTRIAL APPLICABILITY The vinyl chloride plastisol composition of the present invention is industrially useful since it can be used for forming a backing layer of a tile carpet, etc.

Claims

1. a plasticizer-supported porous polyvinyl chloride resin powder obtained by mixing 100 parts by mass of a porous polyvinyl chloride resin powder and 5 to 20 parts by mass of a plasticizer to support the plasticizer in the pores of the porous polyvinyl chloride resin powder; 100 to 900 parts by mass of nitrile rubber; A method for producing a rubber composition, comprising kneading the above.

2. 2. The method for producing a rubber composition according to claim 1, further comprising the step of adding and kneading an additional plasticizer in addition to the supported plasticizer in the plasticizer-supported porous polyvinyl chloride resin powder.

3. 3. The method for producing a rubber composition according to claim 2, wherein the total amount of the supported plasticizer and the additional plasticizer in the plasticizer-supported porous polyvinyl chloride resin powder is 10 to 50 parts by mass.

4. The pore volume of the porous polyvinyl chloride resin powder is 0.09 to 0.45 cm ３ The method for producing a rubber composition according to any one of claims 1 to 3, characterized in that:

5. 5. The method for producing a rubber composition according to claim 1, wherein the supported plasticizer in the plasticizer-supported porous vinyl chloride resin powder is a polyester plasticizer.

6. The method for producing a rubber composition according to claim 5, wherein the polyester plasticizer has an average molecular weight of 400 to 3000 and an SP value of 8.5 to 9.5.

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