JP4942352B2 - Chlorine-containing thermoplastic resin composition - Google Patents

Description

  The present invention relates to a chlorine-containing thermoplastic resin composition that retains low-temperature impact strength and high-temperature mechanical properties and has good processing characteristics, a molded product surface appearance, and color developability.

Vinyl chloride resin is a highly versatile resin, but has the disadvantage of poor impact resistance. In particular, compatibility between impact strength and other mechanical properties and processability is a major problem of this resin. Therefore, many methods have been proposed to improve the impact resistance.
On the other hand, the molded product of chlorinated vinyl chloride resin has a feature that the heat distortion temperature is 20 to 40 ° C. higher than that of the molded product of vinyl chloride resin. Due to this feature, chlorinated vinyl chloride resins can be used for relatively high temperatures, such as hot water pipes and hot household appliances, which cannot be used because they are deformed by heating with conventional vinyl chloride resin moldings. Used for sheets and the like. On the other hand, there is a weak point that the impact resistance at low temperature is inferior.
In order to improve this, it is known to add an impact resistance improver such as ABS resin or MBS resin to chlorinated vinyl chloride resin. Although these impact resistance improvers improve impact resistance at low temperatures, their effects are not sufficient, and the melting characteristics during molding are poor, resulting in difficulties in workability. Various proposals have been made to solve this problem. Patent Documents 1 to 3 listed below propose a technique for adding an MBS resin and further a silicone-containing graft copolymer to a chlorinated vinyl chloride resin. ing.

With respect to the silicone / acrylic composite rubber-based graft copolymer as an impact resistance improver, a proposal has been made in which the particle diameter is controlled for the purpose of improving low temperature impact strength and the like (Patent Document 4).
As described above, various improvements have been investigated for chlorine-containing resins, but those that retain low-temperature impact strength and high-temperature mechanical properties and satisfy good processing characteristics, molded product surface appearance, and color developability have been obtained. Absent.
JP 7-145287 A JP 9-316269 A JP 2001-139746 A JP 2004-331726 A

  An object of the present invention is to provide a chlorine-containing thermoplastic resin composition that retains low-temperature impact strength and high-temperature mechanical properties and has good processing characteristics, a molded product surface appearance, and color development.

  The present invention relates to a vinyl chloride resin, 100 parts by mass of at least one chlorine-containing resin (A) selected from chlorinated vinyl chloride resin having a chlorination degree of 50 to 70% by mass and chlorinated polyethylene, and polyorganosiloxane. Particles in which one or more vinyl monomer units are grafted to a composite rubber including rubber and polyalkyl (meth) acrylate rubber, the number average particle diameter is 300 to 2000 nm, and the total particle diameter is 300 nm or less Is a chlorine-containing thermoplastic resin composition containing 0.1 to 30 parts by mass of silicone / acrylic composite rubber-based graft copolymer particles (B) having a ratio of 20% by volume or less.

  The chlorine-containing thermoplastic resin composition of the present invention retains low-temperature impact strength and high-temperature mechanical properties, has good processing characteristics, molded product surface appearance, and color developability, and is used in various molded products as various industrial materials. Is possible.

  The chlorine-containing resin (A) used in the present invention is at least one selected from vinyl chloride resins, chlorinated vinyl chloride resins having a chlorination degree of 50 to 70% by mass, and chlorinated polyethylene.

  The vinyl chloride resin preferably has an average degree of polymerization of 600 to 1500, more preferably 600 to 1300. When the average degree of polymerization is 600 or more, sufficient mechanical strength is obtained, and when the average degree of polymerization is 1500 or less, processing of the resin composition is easy. Vinyl chloride resins include vinyl chloride homopolymers and other copolymerizable monomers with vinyl chloride (for example, ethylene, propylene, vinyl acetate, allyl chloride, allyl glycidyl ether, acrylic ester, vinyl ether). Etc.) may be used.

The chlorinated vinyl chloride resin has a chlorination degree of 50 to 70% by mass, preferably 60 to 70% by mass, and more preferably 65 to 70% by mass. A composition having sufficient heat resistance can be obtained when the chlorination degree is 50% by mass or more, and the melt viscosity necessary for processing can be maintained when the chlorination degree is 70% by mass or less. As the vinyl chloride resin which is a raw material of the chlorinated vinyl chloride resin, the above-mentioned ones are preferably used.
Specific examples of chlorinated polyethylene include chlorinated polyethylene powder in an aqueous suspension or chlorinated polyethylene dissolved in an organic solvent. In particular, chlorinated polyethylene powder in an aqueous suspension is preferable.
The polyethylene used as the raw material for the chlorinated polyethylene is, for example, an ethylene homopolymer or ethylene and α- having 40% by mass or less (preferably 20% by mass or less) and 12 or less (preferably 3 to 8) carbon atoms. Examples include copolymers obtained by copolymerizing with olefins. Specific examples of the α-olefin include propylene, 1-butene, 1-hexene, 4-methyl-1-pentene and the like. Of the above polyethylene, an ethylene homopolymer is particularly preferred.
The chlorine content of the chlorinated polyolefin is preferably 30 to 40% by mass.

The silicone / acrylic composite rubber-based graft copolymer particles (B) in the present invention include a composite containing a polyorganosiloxane rubber (hereinafter referred to as “S rubber”) and a polyalkyl (meth) acrylate rubber (hereinafter referred to as “A rubber”). One or more vinyl monomer units are grafted to the rubber, the number average particle size is 300 to 2000 nm, and the proportion of particles having a particle size of 300 nm or less in all particles is 20% by volume or less.
The number average particle diameter is preferably 400 nm or more, more preferably 600 nm or more. Further, the number average particle diameter is preferably 1500 nm or less, and more preferably 1300 nm or less.
The number average particle diameter is 300 nm or more, which is preferable from the viewpoint of impact strength development at a low temperature. Moreover, the absolute particle number is ensured at 2000 nm or less, which is preferable for maintaining the impact strength.
In the following description, “silicone / acrylic composite rubber” is abbreviated as “composite rubber”, and “silicone / acrylic composite rubber-based graft copolymer particles (B)” is referred to as “graft copolymer particles (B)”. Abbreviated.

As the S rubber, those having an organosiloxane unit and a vinyl polymerizable functional group-containing organosiloxane unit are preferably used.
Examples of the raw material for the organosiloxane unit include dimethylsiloxanes such as dimethylsiloxane-based cyclics having 3 or more members, and those having 3 to 7 members are preferable. Specific examples include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, and the like. These may be used alone or in combination of two or more. From the viewpoint of easy control of particle size distribution, it is preferable to use octamethylcyclotetrasiloxane, which is a 4-membered ring, as the main component.

  In addition, as a raw material for the vinyl polymerizable functional group-containing organosiloxane unit, it is preferable to use various alkoxysilane compounds containing a vinyl polymerizable functional group in consideration of the reactivity with dimethylsiloxane. Specifically, β-methacryloyloxyethyldimethoxymethylsilane, γ-methacryloyloxypropyldimethoxymethylsilane, γ-methacryloyloxypropylmethoxydimethylsilane, γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropylethoxydiethylsilane, methacryloyloxysilane such as γ-methacryloyloxypropylethoxydiethoxymethylsilane and δ-methacryloyloxybutyldiethoxymethylsilane; vinylsiloxane such as tetramethyltetravinylcyclotetrasiloxane; vinylphenylsilane such as p-vinylphenyldimethoxymethylsilane ; Mercaptosy such as γ-mercaptopropyldimethoxymethylsilane and γ-mercaptopropyltrimethoxysilane; Hexane, and the like. In addition, these vinyl polymerizable functional group containing siloxane can be used individually or in mixture of 2 or more types.

In addition to the monomer unit, a crosslinker unit can be introduced as necessary as a constituent unit of the S rubber. Examples of this raw material include a siloxane-based crosslinking agent.
Examples of the siloxane-based crosslinking agent include trifunctional or tetrafunctional ones such as trimethoxymethylsilane, triethoxyphenylsilane, tetramethoxysilane, tetraethoxysilane, and tetrabutoxysilane.

  As a method for producing S rubber, a mixture of dimethylsiloxane and a vinyl polymerizable functional group-containing organosiloxane, and a latex obtained by emulsifying a mixture containing a siloxane-based cross-linking agent with an emulsifier and water as necessary, are subjected to shearing force by high-speed rotation. After homogenization using a homomixer that produces fine particles with a high pressure generator or a homogenizer that produces fine particles with a jet output from a high-pressure generator, polymerize at high temperature using an acid catalyst, and then neutralize the acid with an alkaline substance. Is mentioned. In making the fine particles, it is preferable to use a homogenizer in that the particle size distribution becomes narrow.

  As an emulsifier, an anionic emulsifier is preferable, and an emulsifier selected from sodium alkylbenzene sulfonate, sodium lauryl sulfate, sodium alkyldiphenyl ether sulfonate, sodium polyoxyethylene alkyl ether sulfate, sodium alkyl sulfonate is used. The In particular, sodium alkylbenzene sulfonate and sodium lauryl sulfate are preferred.

  Examples of the acid catalyst include sulfonic acids such as aliphatic sulfonic acid, aliphatic substituted benzene sulfonic acid, and aliphatic substituted naphthalene sulfonic acid, and mineral acids such as sulfuric acid, hydrochloric acid, and nitric acid. These acid catalysts are used alone or in combination of two or more. Of these, the use of mineral acids such as sulfuric acid, hydrochloric acid, and nitric acid having no micelle forming ability can narrow the particle size distribution of the S rubber latex, and the resin composition resulting from the emulsifier component of the S rubber latex. This is preferable in that the appearance defect of the object can be reduced.

  In addition, the mixing method of the acid catalyst includes (1) a method of mixing the monomer mixture, the emulsifier and water together, and (2) the finely divided latex of the monomer mixture in a high-temperature acid aqueous solution at a constant rate. The method of dripping and (3) The method of dripping the aqueous solution of an acid catalyst all at once or in a short time can be cited as a mixture obtained by previously mixing and emulsifying a monomer mixture, an emulsifier and water. Considering the ease of particle size control, the method (3) is preferable.

The polymerization temperature is preferably 50 ° C. or higher, more preferably 70 ° C. or higher. The polymerization time is 2 hours or more, more preferably 5 hours or more when the acid catalyst is mixed with a monomer mixture, an emulsifier and water to form a fine particle for polymerization.
The polymerization can be stopped by cooling the reaction solution and further neutralizing the latex with an alkaline substance such as caustic soda, caustic potash or sodium carbonate.

  In order to obtain graft copolymer particles (B) having a specific particle diameter in the present invention, as S rubber, 0 to 15% by volume of particles of 10 to 250 nm and 85 to 100% by volume of particles of 250 to 2000 nm. It is preferable to use the contained S rubber. Further, it is more preferable to use a rubber having a particle size distribution (mass average particle size dw / number average particle size dn) of 1.0 to 1.2.

  In the present invention, the A rubber includes a copolymer of an alkyl (meth) acrylate unit and a polyfunctional alkyl (meth) acrylate unit.

  Examples of raw materials for the alkyl (meth) acrylate unit include alkyl acrylates such as methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, and n-lauryl methacrylate. These may be used alone or in combination of two or more. In view of the impact resistance and molding gloss of the chlorine-containing thermoplastic resin composition of the present invention, it is particularly preferable to use n-butyl acrylate.

  Examples of the raw material for the polyfunctional alkyl (meth) acrylate unit include allyl methacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, and triaryl. Examples include lucyanurate and triallyl isocyanurate, and these can be used alone or in combination of two or more.

  In the present invention, the production of A rubber is preferably carried out by adding a monomer mixture for A rubber into the latex of S rubber and impregnating it in S rubber, followed by polymerization.

In the present invention, the composite rubber preferably has a structure in which 1 to 99% by mass of S rubber and 99 to 1% by mass of A rubber are intertwined with each other so that they cannot be separated.
As a method for producing the composite rubber, for example, a method of adding a monomer mixture for A rubber to the latex of S rubber, impregnating the rubber into S rubber, and then polymerizing it is preferable.
Examples of the method of adding the monomer mixture for A rubber to the S rubber include a method of batch-mixing with the S rubber latex and a method of dropping at a constant rate into the S rubber latex. Moreover, as a radical polymerization initiator used for superposition | polymerization, the redox initiator which combined the peroxide type initiator, the azo type initiator, or the oxidizing agent and the reducing agent is used. Among these, a redox initiator is preferable, and a system in which ferrous sulfate, ethylenediaminetetraacetic acid disodium salt, longalite, and hydroperoxide are combined is particularly preferable.

  In the present invention, the graft copolymer particles (B) are obtained by grafting one or more vinyl monomer units to a composite rubber.

  The content of S rubber in the graft copolymer particles (B) is preferably 5 to 70% by mass, and more preferably 10 to 40% by mass. Sufficient impact resistance can be obtained when the S rubber content is 5 mass% or more. Further, when the content of the S rubber is 70% by mass or less, other excellent characteristics in the chlorine-containing thermoplastic resin composition of the present invention can be maintained.

  The content of the composite rubber in the graft copolymer particles (B) is preferably 40 to 90% by mass, and more preferably 60 to 85% by mass. When the content of the composite rubber is 40% by mass or more, the impact resistance becomes good. Further, when the content of the composite rubber is 90% by mass or less, other excellent characteristics in the chlorine-containing thermoplastic resin composition of the present invention can be maintained.

  Examples of vinyl monomers include aromatic alkenyl compounds such as styrene, α-methylstyrene, vinyltoluene, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. And vinyl cyanide compounds such as (meth) acrylic acid esters, acrylonitrile, methacrylonitrile and the like. These can be used alone or in combination of two or more.

The graft bonding of one or more vinyl monomer units to the composite rubber is performed by graft polymerization of the vinyl monomer on the composite rubber.
Graft polymerization can be performed in one step or in multiple steps by adding a vinyl monomer to the latex of the composite rubber and using a radical polymerization method. Moreover, as a radical polymerization initiator used for superposition | polymerization, the redox initiator which combined the peroxide, the azo initiator, or the oxidizing agent and the reducing agent is used. Among these, a redox initiator is preferable, and a system in which ferrous sulfate, ethylenediaminetetraacetic acid disodium salt, longalite, and hydroperoxide are combined is particularly preferable.

Various chain transfer agents and graft crossing agents can be added to the vinyl monomer used in the graft polymerization in order to adjust the molecular weight and graft ratio of the graft polymer.
In the graft polymerization, an emulsifier can be added to stabilize the polymerization latex and to control the average particle size of the graft copolymer particles (B).
Examples of the emulsifier include a cationic emulsifier, an anionic emulsifier, and a nonionic emulsifier, and preferable examples include a sulfonate emulsifier, a sulfate emulsifier, and a carboxylate emulsifier.

  After completion of the graft polymerization, the latex is poured into hot water in which a metal salt such as calcium chloride, calcium acetate, aluminum sulfate is dissolved, salted out and solidified to separate and dry the graft copolymer particles (B). It can be recovered in powder form.

  The graft copolymer particles (B) are contained in the chlorine-containing thermoplastic resin composition of the present invention in an amount of 0.1 to 30 parts by mass with respect to 100 parts by mass of the chlorine-containing resin (A). When the graft copolymer particles (B) are 0.1 parts by mass or more, the effect of modifying the impact strength is sufficiently exhibited, and when they are 30 parts by mass or less, the original properties of the thermoplastic resin are not impaired, and the impact resistance And the appearance is also good.

  In the chlorine-containing thermoplastic resin composition of the present invention, reinforcing agents and fillers such as pigments and dyes, glass fibers, metal fibers, metal flakes, and carbon fibers, as long as the object of the present invention is not impaired, 2,6- Phenolic antioxidants such as di-butyl-4-methylphenol, 4,4'-butylidene-bis (3-methyl-6-t-butylphenol), tris (mixed, mono and dinylphenyl) phosphite, diphenyl Phosphite-based antioxidants such as isodecyl phosphite, sulfur-based antioxidants such as dilauryl thiodipropionate, dimyristyl thiodipropionate, diasterial thiodipropionate, 2-hydroxy-4-octoxybenzophenone Benzotriazole-based UV absorbers such as 2- (2-hydroxy-5-methylphenyl) benzotriazole Agents, light stabilizers such as bis (2,2,6,6) -tetramethyl-4-piperidinyl), antistatic agents such as hydroxylalkylamines and sulfonates, lubricants such as ethylenebisstearylamide, metal soaps, And tetrabromophenol A, decabromophenol oxide, tetrabromide bisphenol A epoxy oligomer, tetrabromide bisphenol A polycarbonate oligomer, antimony trioxide, triphenyl phosphate, phosphate ester, magnesium hydroxide, hydrotalcite, antimony oxide Various additives such as flame retardants such as compounds and molybdenum compounds can be appropriately blended.

  In addition, the chlorine-containing thermoplastic resin composition of the present invention contains a predetermined amount of each of the above-described essential components and optional components as desired, and is a normal one such as a roll, a Banbury mixer, a single screw extruder, a twin screw extruder, or the like. It is produced by kneading batchwise or continuously with a kneader. Usually, it is preferable to use pellets. Moreover, you may use a small amount of solvent as needed.

  Hereinafter, the present invention will be described more specifically with reference to examples. “Part” and “%” represent “part by mass” and “% by mass”, respectively, unless otherwise specified.

In the production examples, the particle sizes of S rubber, composite rubber, and graft copolymer in the latex were measured by the following method.
The latex was diluted with distilled water, 0.1 ml of diluted latex having a concentration of about 3% was used as a sample, a CHDF2000 type particle size distribution meter manufactured by MATEC, USA, flow rate of 1.4 ml / min, pressure of about 2.76 MPa (about 4000 psi) , And measured at a temperature of 35 ° C. For the measurement, a capillary cartridge for particle separation and a carrier liquid were used, and the liquidity was made almost neutral. Before the measurement, a standard curve was prepared by measuring a total of 12 particle diameters of 0.02 to 0.8 μm using monodisperse polystyrene with a known particle diameter manufactured by DUKE Co., USA as a standard particle size substance. .

Moreover, about the average particle diameter, the analysis value in each of mass distribution and number distribution of the said particle diameter measurement result was made into the average particle diameter.
Further, the volume% of the particle diameter of 300 nm or less of the graft copolymer particles (B) is a value of (integrated value of 300 nm or less) / (integrated value of all particle diameters) × 100 of the particle diameter measurement result in mass distribution. It showed in. The volume% of particles of S rubber of 10 nm or more and less than 250 nm and the volume% of particles of 250 nm or more and less than 2000 nm were also determined in the same manner.

(Production Example 1) Production of S rubber latex (L-1) 2 parts of tetraethoxysilane, 0.5 part of γ-methacryloyloxypropyldimethoxymethylsilane and 97.5 parts of octamethylcyclotetrasiloxane were mixed to prepare a siloxane system. 100 parts of a mixture were obtained. To this, 150 parts of an aqueous solution in which 1.00 part of sodium alkylbenzene sulfonate was dissolved was added, stirred for 5 minutes at 10,000 rpm with a homomixer, and then passed twice through a homogenizer at a pressure of 20 MPa to give a stable premixed organosiloxane latex. Obtained.

The latex was put into a separable flask equipped with a cooling condenser, and a mixture of 0.20 parts of sulfuric acid and 49.8 parts of distilled water was added over 3 minutes. The aqueous solution was heated at 80 ° C. for 7 hours and then cooled. Next, after holding at room temperature for 6 hours, the mixture was neutralized with an aqueous caustic soda solution.
The latex was dried at 180 ° C. for 30 minutes and the solid content was determined to be 29.8% by mass. The number average particle diameter (dn) of the S rubber in this latex is 384 nm, the mass average particle diameter (dw) is 403 nm, the ratio of particles of 10 nm or more and less than 250 nm is 0% by volume, and the ratio of particles of 250 nm or more and less than 2000 nm Was 100% by volume.

(Production Example 2) Production of S rubber latex (L-2) 200 parts of an aqueous solution in which 0.7 part of sodium alkylbenzene sulfonate and 0.7 part of alkylbenzene sulfonic acid were dissolved in 100 parts of the same siloxane-based mixture as in Production Example 1 In the same manner as in Production Example 1, a stable premixed organosiloxane latex was obtained. Next, a neutralized latex was obtained in the same manner as in Production Example 1. The latex had a solid content of 29.3%. The number average particle size of the S rubber was 104 nm, the mass average particle size was 214 nm, the proportion of particles of 10 nm or more and less than 250 nm was 40% by volume, and the proportion of particles of 250 nm or more and less than 2000 nm was 60% by volume.

(Production Example 3) Production of Graft Copolymer Particles (B-1) 33.56 parts of S rubber latex (L-1) of Production Example 1 (10.0 parts as a solid content) were placed in a separable flask and distilled. After adding 200 parts of water and mixing, a mixture of 58.8 parts of butyl acrylate, 1.2 parts of allyl methacrylate, and 0.3 parts of cumene hydroperoxide was added.
This separable flask was purged with nitrogen in the atmosphere through a nitrogen stream and heated to 50 ° C. When the liquid temperature reached 50 ° C., an aqueous solution in which 0.001 part of ferrous sulfate, 0.003 part of ethylenediaminetetraacetic acid disodium salt and 0.24 part of Rongalite were dissolved in 10 parts of distilled water was added, and radicals were added. Polymerization was performed. In order to complete the polymerization, this state was maintained for an additional hour to obtain a latex of a composite rubber of S rubber and A rubber.

  After the liquid temperature of the latex dropped to 65 ° C., a mixed solution of 28 parts of methyl methacrylate, 2 parts of butyl acrylate and 0.20 part of cumene hydroperoxide was added dropwise over 1 hour for polymerization. After completion of the dropping, the temperature was kept at 60 ° C. or higher for 1 hour, followed by cooling to obtain a graft copolymer latex in which a methyl methacrylate / butyl acrylate copolymer was grafted to the composite rubber.

  Next, 500 parts of an aqueous solution in which calcium acetate was dissolved at a ratio of 7.5% by mass was heated to 60 ° C. and stirred, and 340 parts of a graft copolymer latex was gradually added dropwise thereto to solidify. After separation, washing with water and drying, graft copolymer particles (B-1) were obtained. Table 1 shows the particle size distribution measurement results of the obtained particles.

(Production Examples 4 and 5) Production of Graft Copolymer Particles (B-2) and (B-3) Polymerization was conducted in the same manner as in Production Example 3 except that the composition was changed to the composition shown in Table 1, and the graft copolymer was produced. Particles (B-2) and (B-3) were obtained. Table 1 shows the particle size distribution measurement results of the obtained particles.

(Examples 1-4 and Comparative Examples 1 and 2)
Using the graft copolymer particles (B-1) to (B-3) obtained in Production Examples 3 to 5, the mixture shown in Table 2 and Table 3 was mixed for 4 minutes with a Henschel mixer, and then the mixture 1-4 were produced. These were roll temperature: 200 ° C., kneading time: 3 minutes after winding, press temperature: 200 ° C., molding time: preheating 5 minutes, pressurization 5 minutes, molding pressure: 7.5 MPa, length 18 mm × width 18 mm X A plate-shaped test piece having a thickness of 3 mm was obtained.

The above specimen is cut according to the following evaluation method and evaluated, and the results obtained are shown in Table 4 and Table 5.
In the evaluation, the measurement criteria and judgment of each item were performed as follows.

(1) Workability (gelation time)
Using a Brabender plast mill, heat the mixer type W-50E attachment to 170 ° C., hold the mixture for 56 minutes, and knead at a rotor speed of 30 rpm until the point showing maximum torque The time required for this was defined as the gel time.

(2) Workability (time to wrap)
The time when the blend was completely charged into the roll bank part was taken as the start time, kneading was carried out with a front-rear roll spacing of 0.3 mm, and the time until the blend melted and wound around the roll was judged.

(3) Izod impact strength Conforms to the method of ASTM D258. (Test piece: Measured at a length of 63.5 mm × width of 12.7 mm × thickness of 3 mm at −10 ° C.)

(4) Coloring property A molded product obtained by a roll and a press is cut into a 10 cm square plate, and the jet blackness is measured using a measuring machine CMS-1500 manufactured by Murakami Color Research Laboratory Co., Ltd. It was measured and evaluated as a value.

Claims (1)

100 parts by mass of vinyl chloride resin, at least one chlorine-containing resin (A) selected from chlorinated vinyl chloride resin having a chlorination degree of 50 to 70% by mass and chlorinated polyethylene, and polyorganosiloxane rubber and polyalkyl A composite rubber containing (meth) acrylate rubber is grafted with one or more vinyl monomer units, the number average particle diameter is 400 to 2000 nm, and the ratio of particles having a particle diameter of 300 nm or less in all particles is A chlorine-containing thermoplastic resin composition containing 0.1 to 30 parts by mass of silicone / acrylic composite rubber-based graft copolymer particles (B) that is 20% by volume or less.