JP7671192B2 - Vinyl chloride resin composition and vinyl chloride resin molded article - Google Patents

Description

The present invention relates to a vinyl chloride resin composition containing a vinyl chloride resin. The present invention also relates to a vinyl chloride resin molded article using the vinyl chloride resin composition.

Vinyl chloride resins have excellent mechanical strength, weather resistance, heat resistance, and chemical resistance. For this reason, the vinyl chloride resins are processed into various molded articles such as pipes, plates, and containers, and are used in many fields.

However, when using vinyl chloride resin to obtain a molded body, stable molding can be difficult because vinyl chloride resin has low thermal stability and is prone to thermal decomposition due to the elimination of hydrogen chloride during heat molding. As a result, the mechanical strength of the obtained molded body may decrease, or the molded body may become discolored.

In addition, in order to increase the thermal stability of vinyl chloride resins, heat stabilizers are sometimes used together with vinyl chloride resins. Known examples of such heat stabilizers include tin-based stabilizers, calcium-zinc-based stabilizers, barium-zinc-based stabilizers, and barium-cadmium-based stabilizers.

The following Patent Document 1 discloses a vinyl chloride resin composition containing a vinyl chloride copolymer and an organotin compound that is liquid at 23°C.

JP 2017-165868 A

In Patent Document 1, an organotin stabilizer that has the function of capturing hydrogen chloride is used, which suppresses the decomposition of the vinyl chloride resin and can increase the thermal stability of the vinyl chloride resin composition to a certain extent.

However, there is a demand for further improvement in the thermal stability of vinyl chloride resin compositions. In addition, when producing a thick molded body, it takes time to cool the molded body to its inside, which makes the vinyl chloride resin more likely to decompose and generate hydrogen chloride. Therefore, when producing a thick molded body, the organotin stabilizer alone may not be able to capture hydrogen chloride gas sufficiently. As a result, the uncaptured hydrogen chloride acts as a starting point for further decomposition of the vinyl chloride resin inside the molded body, and the hydrogen chloride increases, which creates the problem of air bubbles being more likely to form inside the molded body.

Furthermore, because organotin stabilizers are often liquid substances, the heat resistance of vinyl chloride resin molded bodies may decrease depending on the amount of organotin stabilizer added.

The object of the present invention is to provide a vinyl chloride resin composition that can improve thermal stability during hot molding, suppress the generation of bubbles inside the molded body, and improve the heat resistance of the resulting molded body. Another object of the present invention is to provide a vinyl chloride resin molded body using the vinyl chloride resin composition.

The inventors have found that by using a metal salt of an aliphatic carboxylic acid to supplement the hydrogen chloride trapping function, it is possible to effectively trap hydrogen chloride that cannot be completely trapped by an organotin stabilizer. Specifically, the hydrogen chloride trapping function of at least one metal salt of an aliphatic carboxylic acid selected from the group consisting of sodium salts of aliphatic carboxylic acids and calcium salts of aliphatic carboxylic acids can suppress the generation of bubbles caused by hydrogen chloride.

The inventors have also discovered that the use of at least one antioxidant component selected from the group consisting of phenol-based antioxidants, amine-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants can improve thermal stability in the early stages of molding. As a result, they have discovered that the generation of hydrogen chloride due to decomposition of vinyl chloride resin, which is the starting point for the generation of bubbles inside the molded body, can be reduced, and the above-mentioned problems can be solved, leading to the creation of the present invention.

According to a broad aspect of the present invention, there is provided a vinyl chloride resin composition comprising a vinyl chloride resin, an organotin stabilizer, at least one metal salt of an aliphatic carboxylic acid selected from the group consisting of sodium salts of aliphatic carboxylic acids and calcium salts of aliphatic carboxylic acids, and at least one antioxidant component selected from the group consisting of phenolic antioxidants, amine antioxidants, phosphorus antioxidants, and sulfur antioxidants.

In a particular aspect of the vinyl chloride resin composition according to the present invention, the content of the organotin stabilizer is 0.1 parts by weight or more and 3.0 parts by weight or less per 100 parts by weight of the vinyl chloride resin.

In a specific aspect of the vinyl chloride resin composition according to the present invention, the content of the metal salt of the aliphatic carboxylic acid is 0.1 parts by weight or more and 3.0 parts by weight or less per 100 parts by weight of the vinyl chloride resin.

In a particular aspect of the vinyl chloride resin composition according to the present invention, the content of the antioxidant component is 0.1 parts by weight or more and 5.0 parts by weight or less per 100 parts by weight of the vinyl chloride resin.

In a particular aspect of the vinyl chloride resin composition according to the present invention, the organotin stabilizer includes a tin mercapto stabilizer.

In a particular aspect of the vinyl chloride resin composition according to the present invention, the metal salt of the aliphatic carboxylic acid includes a metal salt of adipic acid.

According to a broad aspect of the present invention, there is provided a vinyl chloride resin molded article which is a molded article of the vinyl chloride resin composition described above.

The vinyl chloride resin composition according to the present invention includes a vinyl chloride resin, an organotin stabilizer, a metal salt of an aliphatic carboxylic acid, and an antioxidant component. In the vinyl chloride resin composition according to the present invention, the metal salt of the aliphatic carboxylic acid is at least one selected from the group consisting of sodium salts of aliphatic carboxylic acids and calcium salts of aliphatic carboxylic acids. In the vinyl chloride resin composition according to the present invention, the antioxidant component is at least one selected from the group consisting of phenol-based antioxidants, amine-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants. Since the vinyl chloride resin composition according to the present invention has the above-mentioned configuration, it is possible to improve the thermal stability during hot molding, suppress the generation of bubbles inside the molded body, and improve the heat resistance of the obtained molded body.

The details of the present invention are explained below.

(Vinyl chloride resin composition)
The vinyl chloride resin composition according to the present invention contains a vinyl chloride resin, an organotin stabilizer, a metal salt of an aliphatic carboxylic acid, and an antioxidant component. In the vinyl chloride resin composition according to the present invention, the metal salt of an aliphatic carboxylic acid is at least one selected from the group consisting of a sodium salt of an aliphatic carboxylic acid and a calcium salt of an aliphatic carboxylic acid. In the vinyl chloride resin composition according to the present invention, the antioxidant component is at least one selected from the group consisting of a phenol-based antioxidant, an amine-based antioxidant, a phosphorus-based antioxidant, and a sulfur-based antioxidant.

The vinyl chloride resin composition according to the present invention has the above-mentioned configuration, and therefore can improve the thermal stability during hot molding. As a result, the mechanical strength of the molded body obtained can be increased and discoloration of the molded body can be prevented. In addition, the vinyl chloride resin composition according to the present invention has the above-mentioned configuration, and therefore can suppress the generation of bubbles inside the molded body and can improve the heat resistance of the molded body obtained. In particular, even when a thick molded body is produced, the generation of bubbles inside the molded body can be suppressed and the heat resistance of the molded body obtained can be improved.

The following describes each component contained in the vinyl chloride resin composition.

(Vinyl chloride resin)
The vinyl chloride resin according to the present invention is a resin having chlorine atoms. The vinyl chloride resin may be a chlorinated vinyl chloride resin or a non-chlorinated vinyl chloride resin. The chlorinated vinyl chloride resin is a resin obtained by chlorinating a vinyl chloride resin. From the viewpoint of further improving heat resistance, the vinyl chloride resin is preferably a chlorinated vinyl chloride resin. Only one type of the vinyl chloride resin may be used, or two or more types may be used in combination.

Examples of the vinyl chloride resin include homopolymers of vinyl chloride monomers, and copolymers of vinyl chloride monomers and vinyl monomers copolymerizable with vinyl chloride monomers.

Examples of vinyl monomers copolymerizable with the vinyl chloride monomer include vinyl esters such as vinyl acetate and vinyl propionate; vinyl ether compounds; cyano group-containing compounds such as acrylonitrile; halogen compounds such as vinylidene chloride and vinyl fluoride; olefins such as ethylene and propylene; carboxyl group-containing compounds such as itaconic acid, maleic acid, and fumaric acid; non-aromatic carboxylic acid anhydrides such as maleic anhydride; acrylic acid esters such as methyl (meth)acrylate and ethyl (meth)acrylate; and imide compounds such as maleimide. Only one type of the vinyl monomers may be used, or two or more types may be used in combination.

The polymerization method of the vinyl chloride monomer and the polymerization method of the vinyl chloride monomer and the vinyl monomer are not particularly limited. Examples of the polymerization method include suspension polymerization, emulsion polymerization, solution polymerization, bulk polymerization, and precipitation polymerization. From the viewpoint of efficiently obtaining a vinyl chloride resin, the polymerization method is preferably suspension polymerization, emulsion polymerization, solution polymerization, or precipitation polymerization.

The chlorinated vinyl chloride resin is preferably obtained by polymerizing the vinyl chloride monomer or the chlorinated vinyl monomer and the vinyl monomer to obtain a vinyl chloride resin, and then chlorinating the obtained vinyl chloride resin.

The method of chlorinating the vinyl chloride resin is not particularly limited. Examples of the method of chlorinating the vinyl chloride resin include a method in which the vinyl chloride resin is placed in an aqueous solvent to obtain a suspension, and then chlorine is added to react the vinyl chloride resin with the chlorine. This chlorination reaction proceeds under heating conditions or light irradiation conditions.

From the viewpoint of further increasing the thermal stability of the chlorinated vinyl chloride resin, it is preferable that the chlorination reaction is carried out under heating conditions.

To further increase the efficiency of the chlorination reaction, the heating temperature is preferably 80°C or higher and 140°C or lower.

The chlorine content of the vinyl chloride resin is preferably 56.8% by weight or more, and preferably 72% by weight or less. The chlorine content of the vinyl chloride resin is the content of chlorine atoms in 100% by weight of the vinyl chloride resin. If the chlorine content of the vinyl chloride resin is equal to or more than the lower limit, the heat resistance of the resulting molded article can be further improved. If the chlorine content of the vinyl chloride resin is equal to or less than the upper limit, the moldability can be further improved, and the impact resistance and surface smoothness of the resulting molded article can be further improved.

When the vinyl chloride resin is a chlorinated vinyl chloride resin, the chlorine content of the chlorinated vinyl chloride resin is preferably 56.8% by weight or more, more preferably 60% by weight or more, and even more preferably 61.5% by weight or more, and preferably 72% by weight or less, and more preferably 67.5% by weight or less, based on 100% by weight of the chlorinated vinyl chloride resin. When the chlorine content of the chlorinated vinyl chloride resin is equal to or more than the lower limit, the heat resistance of the obtained molded product can be further improved. When the chlorine content of the chlorinated vinyl chloride resin is equal to or less than the upper limit, the moldability can be further improved, and the impact resistance and surface smoothness of the obtained molded product can be further improved.

The chlorine content of the vinyl chloride resin (if the vinyl chloride resin is a chlorinated vinyl chloride resin, the chlorine content of the chlorinated vinyl chloride resin) can be determined by potentiometric titration in accordance with JIS K7229.

The degree of polymerization of the vinyl chloride resin is preferably 500 or more, more preferably 600 or more, and preferably 2000 or less, more preferably 1200 or less, and even more preferably 900 or less. If the degree of polymerization is equal to or greater than the lower limit, the mechanical strength of the molded body can be further increased. If the degree of polymerization is equal to or less than the upper limit, there is no need to raise the temperature during molding, and moldability can be further improved.

The vinyl chloride resin contained in the vinyl chloride resin composition is preferably in the form of particles. The volume average particle diameter of the vinyl chloride resin particles is preferably 0.1 μm or more and preferably 500 μm or less. When the volume average particle diameter is equal to or more than the lower limit, the handling properties can be further improved. When the volume average particle diameter is equal to or less than the upper limit, the moldability can be further improved.

The volume average particle diameter of the vinyl chloride resin is the average diameter measured on a volume basis, and is the median diameter at 50% (D50). The volume average particle diameter can be measured by a laser diffraction/scattering method, etc.

(Organotin stabilizer)
The vinyl chloride resin composition contains an organotin stabilizer. In the vinyl chloride resin composition according to the present invention, the organotin stabilizer is a compound that inhibits decomposition of the vinyl chloride resin and captures hydrogen chloride generated during decomposition of the vinyl chloride resin.

The above-mentioned organotin stabilizers include tin mercapto stabilizers, tin malate stabilizers, tin carboxylate stabilizers, and tin sulfide stabilizers. The above-mentioned organotin stabilizers may be used alone or in combination of two or more kinds.

The above-mentioned tin mercapto stabilizers include monoalkyltin mercapto, dialkyltin mercapto, monoalkyltin mercapto polymer, dialkyltin mercapto polymer, monoalkyltin mercapto sulfide, and dialkyltin mercapto sulfide.

The above-mentioned tin maleate stabilizers include monoalkyl tin maleates, dialkyl tin maleates, monoalkyl tin maleate polymers, and dialkyl tin maleate polymers.

Examples of the tin carboxylate stabilizers include monoalkyltin carboxylates and dialkyltin carboxylates.

Examples of the tin sulfide stabilizers include monoalkyltin sulfides and dialkyltin sulfides.

The organotin stabilizer is preferably an organotin heat stabilizer. Examples of the organotin heat stabilizer include dioctyltin diuralate, dioctyltin malate, and dioctyltin mercaptide.

From the viewpoint of more effectively preventing initial coloring during heat molding and improving thermal stability during heat molding, the above-mentioned organotin stabilizer preferably contains a tin mercapto stabilizer, more preferably contains a dialkyltin mercapto, and even more preferably contains a dioctyltin mercapto.

In order to more effectively exert the effects of the present invention, it is preferable that the vinyl chloride resin composition contains a tin sulfide stabilizer.

The content of the organotin stabilizer is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, even more preferably 0.5 parts by weight or more, particularly preferably 0.8 parts by weight or more, and most preferably 1.0 parts by weight or more, relative to 100 parts by weight of the vinyl chloride resin. The content of the organotin stabilizer is preferably 5.0 parts by weight or less, more preferably 3.0 parts by weight or less, even more preferably 2.5 parts by weight or less, particularly preferably 2.2 parts by weight or less, and most preferably 2.0 parts by weight or less, relative to 100 parts by weight of the vinyl chloride resin. If the content of the organotin stabilizer is equal to or more than the lower limit, the thermal stability during hot molding can be more effectively improved, and the generation of bubbles in the molded body can be more effectively suppressed. If the content of the organotin stabilizer is equal to or less than the upper limit, the heat resistance of the obtained molded body can be more effectively improved.

(Metal salts of aliphatic carboxylic acids)
The vinyl chloride resin composition contains at least one metal salt of an aliphatic carboxylic acid selected from the group consisting of sodium salts of aliphatic carboxylic acids and calcium salts of aliphatic carboxylic acids. The metal salts of the aliphatic carboxylic acids may be used alone or in combination of two or more. The carboxylic acid in the aliphatic carboxylic acid may be a monocarboxylic acid or a polycarboxylic acid. The polycarboxylic acid may be a dicarboxylic acid. The sodium salt of the aliphatic carboxylic acid may be disodium aliphatic carboxylic acid.

The metal salt of the aliphatic carboxylic acid described above captures the hydrogen chloride generated during the decomposition of the vinyl chloride resin, thereby suppressing the generation of bubbles caused by hydrogen chloride and improving the thermal stability during hot molding.

Examples of the metal salts of the above aliphatic carboxylic acids include metal salts of adipic acid, metal salts of sebacic acid, metal salts of azelaic acid, metal salts of suberic acid, and metal salts of pimelic acid. Examples of the aliphatic carboxylic acids constituting the above metal salts of aliphatic carboxylic acids include adipic acid, sebacic acid, azelaic acid, suberic acid, and pimelic acid.

From the viewpoint of improving the thermal stability during heat molding, the number of carbon atoms in the metal salt of the aliphatic carboxylic acid is preferably 4 or more, more preferably 5 or more, and even more preferably 6 or more, and is preferably 16 or less, more preferably 12 or less, and even more preferably 8 or less. From the viewpoint of improving the thermal stability during heat molding, it is preferable that the metal salt of the aliphatic carboxylic acid has a chain hydrocarbon skeleton having a carbon number of 2 to 14.

From the viewpoint of improving the dispersion of the metal salt of the aliphatic carboxylic acid and more effectively exerting the effects of the present invention, it is preferable that the number of COOX groups in the metal salt of the aliphatic carboxylic acid is 2 (X is a metal, and X may be shared between the two COOX groups) and the number of carbon atoms in the metal salt of the aliphatic carboxylic acid is 6 to 16. The number of carbon atoms in the metal salt of the aliphatic carboxylic acid includes the number of carbon atoms in the COOX groups.

Examples of the metal salt of an aliphatic carboxylic acid having the above-mentioned preferred embodiment include a metal salt of adipic acid, a metal salt of sebacic acid, a metal salt of azelaic acid, a metal salt of suberic acid, and a metal salt of pimelic acid. The metal salt of the aliphatic carboxylic acid preferably contains at least one metal salt of an aliphatic carboxylic acid selected from the group consisting of a metal salt of adipic acid, a metal salt of sebacic acid, a metal salt of azelaic acid, a metal salt of suberic acid, and a metal salt of pimelic acid. By using these preferred metal salts of aliphatic carboxylic acids, it is possible to more effectively suppress the generation of bubbles inside the molded body due to the capture of hydrogen chloride and to further improve the thermal stability during heat molding. From the viewpoint of more effectively suppressing the generation of bubbles inside the molded body due to the capture of hydrogen chloride and further improving the thermal stability during heat molding, it is particularly preferable that the metal salt of the aliphatic carboxylic acid contains a metal salt of adipic acid.

The content of the metal salt of the aliphatic carboxylic acid is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, even more preferably 0.3 parts by weight or more, particularly preferably 0.7 parts by weight or more, and most preferably 1.0 parts by weight or more, relative to 100 parts by weight of the vinyl chloride resin. The content of the metal salt of the aliphatic carboxylic acid is preferably 5.0 parts by weight or less, more preferably 3.0 parts by weight or less, even more preferably 2.5 parts by weight or less, particularly preferably 2.0 parts by weight or less, and most preferably 1.5 parts by weight or less, relative to 100 parts by weight of the vinyl chloride resin. When the content of the metal salt of the aliphatic carboxylic acid is equal to or more than the lower limit, the thermal stability during hot molding can be improved more effectively, and the generation of bubbles in the molded body can be more effectively suppressed. When the content of the metal salt of the aliphatic carboxylic acid is equal to or less than the upper limit, the thermal stability during hot molding can be improved more effectively.

(Antioxidant component)
The vinyl chloride resin composition contains at least one antioxidant component selected from the group consisting of phenolic antioxidants, amine antioxidants, phosphorus antioxidants, and sulfur antioxidants. The antioxidant components may be used alone or in combination of two or more.

The antioxidant component improves the thermal stability of the vinyl chloride resin composition at the initial stage of molding, reducing the amount of hydrogen chloride generated by decomposition of the vinyl chloride resin and suppressing the generation of bubbles in the molded product.

The phenol-based antioxidant is an antioxidant having a phenol skeleton. The amine-based antioxidant is an antioxidant having an amino group. The phosphorus-based antioxidant is an antioxidant containing a phosphorus atom. The sulfur-based antioxidant is an antioxidant containing a sulfur atom.

The above phenolic antioxidants include 2,6-di-t-butyl-p-cresol (BHT), butyl hydroxyanisole (BHA), 2,6-di-t-butyl-4-ethylphenol, stearyl-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2,2'-methylene bis-(4-methyl-6-butylphenol), 2,2'-methylene bis-(4-ethyl-6-t-butylphenol), 4,4'-butylidene-bis-(3-methyl-6-t-butylphenol), 1,1,3-trimethyl-2,2'-triphenylphosphine oxide, ... 1,3,3-tris-(2-methyl-hydroxy-5-t-butylphenyl)butane, tetrakis[methylene-3-(3',5'-di-t-butyl-4-hydroxyphenyl)propionate]methane, 1,3,3-tris-(2-methyl-4-hydroxy-5-t-butylphenol)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, and bis(3-t-butyl-4-hydroxy-5-methylbenzenepropanoic acid)ethylenebis(oxyethylene).

Examples of the amine-based antioxidants include octylated diphenylamine, phenyl-β-naphthylamine, N,N'-diphenyl-p-phenylenediamine, and phenothiazine.

The above phosphorus-based antioxidants include tridecyl phosphite, tris(tridecyl)phosphite, triphenyl phosphite, trinonylphenyl phosphite, bis(tridecyl)pentaerythritol diphosphite, bis(decyl)pentaerythritol diphosphite, tris(2,4-di-t-butylphenyl)phosphite, bis(2,4-di-t-butyl-6-methylphenyl)ethyl ester phosphorous acid, tris(2,4-di-t-butylphenyl)phosphite, and 2,2'-methylenebis(4,6-di-t-butyl-1-phenyloxy)(2-ethylhexyloxy)phosphorus.

The above-mentioned sulfur-based antioxidants include dioctadecyl 3,3'-thiodipropionate, bis[2-methyl-4-(3-n-laurylthiopropionyloxy)-5-t-butylphenyl]sulfide, dilauryl thiodipropionate, diisostearyl thiodipropionate, and mercaptobenzthiazole.

The content of the antioxidant component is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, even more preferably 0.3 parts by weight or more, particularly preferably 0.7 parts by weight or more, and most preferably 1.0 parts by weight or more, relative to 100 parts by weight of the vinyl chloride resin. The content of the antioxidant component is preferably 5.0 parts by weight or less, more preferably 3.0 parts by weight or less, even more preferably 2.5 parts by weight or less, particularly preferably 2.0 parts by weight or less, and most preferably 1.5 parts by weight or less, relative to 100 parts by weight of the vinyl chloride resin. When the content of the antioxidant component is equal to or more than the lower limit and equal to or less than the upper limit, the generation of bubbles in the molded body can be more effectively suppressed. In particular, when the content of the antioxidant component is equal to or more than the lower limit, the generation of bubbles in the molded body can be significantly effectively suppressed.

(Other ingredients)
The vinyl chloride resin composition may contain various additives as necessary. Examples of the additives include heat stabilizing aids, lubricants, processing aids, impact modifiers, heat resistance improvers, UV absorbers, antistatic agents, light stabilizers, fillers, pigments, and plasticizers. The additives may be used alone or in combination of two or more.

The heat stabilization aid is not particularly limited, and examples thereof include epoxidized soybean oil, phosphate esters, polyols, hydrotalcite, and zeolites. Only one type of the heat stabilization aid may be used, or two or more types may be used in combination.

The lubricants include internal lubricants and external lubricants. The internal lubricants are used to reduce the flow viscosity of the molten resin during molding and to prevent frictional heat generation. The internal lubricants are not particularly limited, and examples thereof include butyl stearate, lauryl alcohol, stearyl alcohol, epoxy soybean oil, glycerin monostearate, stearic acid, and bisamide. The external lubricants are used to increase the sliding effect between the molten resin and the metal surface during molding. The external lubricants are not particularly limited, and examples thereof include paraffin wax, polyolefin wax, ester wax, and montanic acid wax. Only one type of the lubricants may be used, or two or more types may be used in combination.

The processing aid is not particularly limited, and examples thereof include acrylic processing aids. Examples of the acrylic processing aids include alkyl acrylate-alkyl methacrylate copolymers having a weight average molecular weight of 100,000 to 2,000,000. Specific examples include n-butyl acrylate-methyl methacrylate copolymers and 2-ethylhexyl acrylate-methyl methacrylate-butyl methacrylate copolymers. Only one type of the processing aids may be used, or two or more types may be used in combination.

The impact modifier is not particularly limited, and examples thereof include methyl methacrylate-butadiene-styrene copolymer (MBS), chlorinated polyethylene, and acrylic rubber. The impact modifier may be used alone or in combination of two or more kinds.

The heat resistance improver is not particularly limited, and examples thereof include α-methylstyrene-based and N-phenylmaleimide-based resins. Only one type of the heat resistance improver may be used, or two or more types may be used in combination.

The above-mentioned UV absorbers are not particularly limited, and examples thereof include salicylic acid ester-based UV absorbers, benzophenone-based UV absorbers, benzotriazole-based UV absorbers, and cyanoacrylate-based UV absorbers. The above-mentioned UV absorbers may be used alone or in combination of two or more kinds.

The light stabilizer is not particularly limited, and examples thereof include hindered amine light stabilizers. Only one type of the light stabilizer may be used, or two or more types may be used in combination.

The above fillers are not particularly limited, and examples thereof include calcium carbonate and talc. The above fillers may be used alone or in combination of two or more.

The pigment is not particularly limited, and examples thereof include organic pigments and inorganic pigments. Examples of the organic pigments include azo-based organic pigments, phthalocyanine-based organic pigments, threne-based organic pigments, and dye lake-based organic pigments. Examples of the inorganic pigments include oxide-based inorganic pigments, molybdenum chromate-based inorganic pigments, sulfide/selenide-based inorganic pigments, and ferrocyanide-based inorganic pigments. From the viewpoint of further increasing transparency, it is preferable that the vinyl chloride resin composition does not contain the above pigments.

The plasticizer may be added to improve processability during molding. The addition of a plasticizer may reduce the heat resistance of the molded product, so it is preferable to add a small amount of plasticizer. The plasticizer is not particularly limited, and examples include dibutyl phthalate, di-2-ethylhexyl phthalate, and di-2-ethylhexyl adipate. Only one type of the plasticizer may be used, or two or more types may be used in combination.

The vinyl chloride resin composition may contain a stabilizer other than the organotin stabilizer. Examples of the stabilizers other than the organotin stabilizer include lead-based stabilizers, calcium-zinc-based stabilizers, barium-zinc-based stabilizers, and barium-cadmium-based stabilizers. Examples of the lead-based stabilizers include tribasic lead sulfate, tetrabasic lead sulfate, basic lead sulfite, dibasic lead phosphite, dibasic lead phthalate, tribasic lead maleate, dibasic lead stearate, and basic sulfite and phosphite.

(Vinyl chloride resin molded body)
The vinyl chloride resin molded article is formed using the vinyl chloride resin composition. The vinyl chloride resin composition can be used alone to obtain the vinyl chloride resin molded article. The vinyl chloride resin molded article is obtained by molding the vinyl chloride resin composition. The vinyl chloride resin molded article is a molded article of the vinyl chloride resin composition.

The shape of the vinyl chloride resin molded body is not particularly limited, and examples include pipes, plates, and containers. The vinyl chloride resin molded body is preferably in the form of a plate, and more preferably in the form of a flat plate. Plates include sheet and film shapes.

The molding method of the vinyl chloride resin composition is not particularly limited, and examples thereof include extrusion molding, injection molding, calendar molding, and press molding.

The molding machine used for molding is not particularly limited, and examples include a single screw extruder, a twin screw counter-rotating parallel extruder, a twin screw counter-rotating conical extruder, and a twin screw co-rotating extruder. When molding using the above molding machines, there are no particular limitations on the mold and resin temperature, etc.

The vinyl chloride resin composition according to the present invention can enhance thermal stability during hot molding and suppress the generation of bubbles inside the molded body, so it is preferable that the vinyl chloride resin molded body is a vinyl chloride injection molded body.

The present invention will be specifically described below by giving examples and comparative examples. The present invention is not limited to the following examples.

The following materials were prepared:

(Vinyl chloride resin)
Polyvinyl chloride resin (Tokuyama Sekisui Kogyo Co., Ltd. "TS-800E", chlorine content 56.8% by weight, polymerization degree 800)

(Organotin stabilizer)
Dioctyltin mercapto stabilizer (Dioctyltin mercapto, "TVS#8940" manufactured by Nitto Kasei Kogyo Co., Ltd.)

(Metal salts of aliphatic carboxylic acids)
Sodium salt of aliphatic carboxylic acid (disodium adipate, manufactured by TCI)
Calcium salt of an aliphatic carboxylic acid (calcium adipate, Alfa Chemistry)

(Antioxidant component)
Phenol-based antioxidant (BASF "IRGANOX1010")
Amine-based antioxidant (BASF "IRGANOX 5057")
Phosphorus-based antioxidant (BASF "IRGAFOS168")
Sulfur-based antioxidant (BASF "IRGANOX PS 802 FL")

(Lubricant)
Polyethylene wax ("Hiwax 220RKT" manufactured by Mitsui Petrochemical Industries, Ltd.)

(Examples 1 to 20 and Comparative Examples 1 to 10)
The types and amounts of the ingredients were as shown in Tables 1 to 5 below, and each ingredient was added to a Henschel mixer (Kawada Kogyo Co., Ltd.) and mixed for 5 minutes to obtain a vinyl chloride resin composition. The obtained vinyl chloride resin composition was kneaded under the following conditions to obtain a sheet having a thickness of 1.0 mm.

[conditions]
Roll: Yasuda Seiki Seisakusho Co., Ltd. mixing roll Roll temperature: 190°C
Roll time: 3 minutes (after winding)

(evaluation)
(1) Thermal Stability The obtained sheet was cut into a length of 30 mm x width of 30 mm to obtain a test sample A. The test sample A was placed in a gear oven (manufactured by Espec Corporation) and heated so that the temperature inside the oven reached 200°C. After the start of heating, the test sample A was visually observed at 10-minute intervals, and the time at which it was possible to confirm that blackening had begun was recorded, and the thermal stability was evaluated according to the following criteria.

[Criteria for thermal stability]
○○: The time when it was possible to confirm that the blackening had begun was 70 minutes or more after the start of heating. ○: The time when it was possible to confirm that the blackening had begun was 50 or 60 minutes after the start of heating. ×: The time when it was possible to confirm that the blackening had begun was 40 minutes or less after the start of heating.

(2) Air Bubble Suppression Performance The obtained sheets were overlapped and pressed under the following conditions to obtain a pressed sample.

[conditions]
Press: Kodaira Manufacturing Co., Ltd. heat press molding machine (press surface material: SUS304)
Press temperature: 200°C
Press time: Preheating 3 minutes + pressing 10 minutes Press pressure: 150 kgf/ ^cm2
Press sample size: thickness 10.0 mm x length 200 mm x width 200 mm

The obtained press sample was cut into a length of 30 mm x width of 30 mm to obtain test sample B (molded body). Test sample B (molded body) was placed in a gear oven (manufactured by Espec Corporation) and heated so that the temperature inside the oven reached 200°C. After 60 minutes, test sample B (molded body) was cut vertically, and the bubbles inside test sample B (molded body) were confirmed, and the bubble suppression performance was evaluated according to the following criteria.

[Criteria for evaluating bubble suppression performance]
○○: No bubbles (no visible bubbles)
○: Less than 10 tiny bubbles (less than 1 mm) are present, and no bubbles of 1 mm or larger are present. △: 10 to less than 15 tiny bubbles (less than 1 mm) are present, and no bubbles of 1 mm or larger are present. ×: 15 or more tiny bubbles (less than 1 mm) are present, or bubbles of 1 mm or larger are present.

(3) Heat Resistance of Molded Article The obtained sheets were overlapped and pressed under the following conditions to obtain a pressed sample.

[conditions]
Press: Toho Machinery Co., Ltd. heat press molding machine Press temperature: 200°C
Press time: Preheating 3 minutes + pressing 2 minutes Press pressure: 150 kgf/ ^cm2
Press sample size: thickness 3.0 mm x length 200 mm x width 200 mm

The obtained press sample was cut into a length of 30 mm x width of 30 mm to obtain test sample C (molded body). The Vicat softening temperature of test sample C (molded body) was measured in accordance with JIS K7206. The heat resistance of test sample C (molded body) was evaluated according to the following criteria.

[Criteria for determining heat resistance of molded products]
○○: Vicat softening temperature is 76°C or higher. ○: Vicat softening temperature is 74°C or higher but less than 76°C. ×: Vicat softening temperature is less than 74°C.

The results are shown in Tables 1 to 5.

Claims (6)

A polyvinyl chloride resin,
An organotin stabilizer;
At least one metal salt of an aliphatic carboxylic acid selected from the group consisting of sodium salts of an aliphatic carboxylic acid and calcium salts of an aliphatic carboxylic acid;
and at least one antioxidant component selected from the group consisting of a phenol-based antioxidant, an amine-based antioxidant, a phosphorus-based antioxidant, and a sulfur-based antioxidant ;
The vinyl chloride resin composition, wherein the metal salt of an aliphatic carboxylic acid includes a metal salt of adipic acid . The vinyl chloride resin composition according to claim 1, wherein the content of the organotin stabilizer is 0.1 parts by weight or more and 3.0 parts by weight or less per 100 parts by weight of the vinyl chloride resin. The vinyl chloride resin composition according to claim 1 or 2, wherein the content of the metal salt of the aliphatic carboxylic acid is 0.1 parts by weight or more and 3.0 parts by weight or less per 100 parts by weight of the vinyl chloride resin. The vinyl chloride resin composition according to any one of claims 1 to 3, wherein the content of the antioxidant component is 0.1 parts by weight or more and 5.0 parts by weight or less per 100 parts by weight of the vinyl chloride resin. The vinyl chloride resin composition according to any one of claims 1 to 4, wherein the organotin stabilizer includes a tin mercapto stabilizer. A vinyl chloride resin molded article, which is a molded article of the vinyl chloride resin composition according to any one of claims 1 to 5 .