JP7680849B2 - 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, a heat stabilizer may be used together with the vinyl chloride resin to increase the thermal stability of the vinyl chloride resin. Known examples of the heat stabilizer include tin-based stabilizers, lead-based stabilizers, calcium-zinc-based stabilizers, barium-zinc-based stabilizers, and barium-cadmium-based stabilizers.

Patent Document 1 discloses a vinyl chloride resin composition containing a vinyl chloride copolymer and an organotin compound that is liquid at 23°C. The vinyl chloride copolymer contained in the vinyl chloride resin composition is a copolymer of a vinyl chloride monomer and a second monomer having a polyalkylene glycol group and an alkyl ether skeleton or an allyl ether skeleton at one end. In the vinyl chloride resin composition, the content of the organotin compound is 3 parts by weight or more per 100 parts by weight of the vinyl chloride copolymer.

JP 2017-165868 A

In Patent Document 1, the decomposition of vinyl chloride resin can be suppressed by using an organotin compound, and the thermal stability of the vinyl chloride resin composition can be increased to a certain extent.

However, the hydrogen chloride generated during hot molding cannot be sufficiently captured by organotin compounds alone, resulting in insufficient thermal stability of the vinyl chloride resin composition. In addition, the hydrogen chloride may corrode the metal surfaces of molds and the like. As a result, the long-term production of molded articles using the vinyl chloride resin composition is difficult. Furthermore, because organotin stabilizers are often liquid substances, the heat resistance of vinyl chloride resin molded articles 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, inhibit corrosion of metal surfaces, and improve the heat resistance of the resulting molded article. Another object of the present invention is to provide a vinyl chloride resin molded article using the vinyl chloride resin composition.

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, and a sodium salt of an aliphatic carboxylic acid, the vinyl chloride resin content being 80% by weight or more and 99% by weight or less, the organotin stabilizer content being 0.1% by weight or more and 2.5% by weight or less, and the sodium salt of the aliphatic carboxylic acid content being 0.1% by weight or more and 2.0% by weight or less, and the sodium content being 0.08% by weight or more and 0.5% by weight or less, in 100% by weight of the vinyl chloride resin composition.

In a particular aspect of the vinyl chloride resin composition according to the present invention, the sodium number in the sodium salt of the aliphatic carboxylic acid is 2, and the carbon number in the sodium salt of the aliphatic carboxylic acid is 4 or more and 16 or less.

In a particular aspect of the vinyl chloride resin composition according to the present invention, the sodium salt of the aliphatic carboxylic acid is disodium adipate.

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

In a specific aspect of the vinyl chloride resin composition according to the present invention, the vinyl chloride resin composition does not contain an inorganic filler, or contains an inorganic filler in an amount of 15% by weight or less based on 100% by weight of the vinyl chloride resin composition.

In a particular aspect of the vinyl chloride resin composition according to the present invention, the vinyl chloride resin composition is a vinyl chloride resin composition for injection molding.

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 contains a vinyl chloride resin, an organotin stabilizer, and a sodium salt of an aliphatic carboxylic acid. In the vinyl chloride resin composition according to the present invention, the content of the vinyl chloride resin is 80% by weight or more and 99% by weight or less, the content of the organotin stabilizer is 0.1% by weight or more and 2.5% by weight or less, and the content of the sodium salt of the aliphatic carboxylic acid is 0.1% by weight or more and 2.0% by weight or less, in 100% by weight of the vinyl chloride resin composition. In the vinyl chloride resin composition according to the present invention, the content of sodium is 0.08% by weight or more and 0.5% by weight or less, in 100% by weight of the vinyl chloride resin composition. 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, to suppress corrosion of the metal surface, and to improve the heat resistance of the obtained molded body.

The present invention is described in detail below.

(Vinyl chloride resin composition)
The vinyl chloride resin composition according to the present invention contains a vinyl chloride resin, an organotin stabilizer, and a sodium salt of an aliphatic carboxylic acid. In the vinyl chloride resin composition according to the present invention, the content of the vinyl chloride resin is 80% by weight or more and 99% by weight or less, the content of the organotin stabilizer is 0.1% by weight or more and 2.5% by weight or less, and the content of the sodium salt of the aliphatic carboxylic acid is 0.1% by weight or more and 2.0% by weight or less, in 100% by weight of the vinyl chloride resin composition. In the vinyl chloride resin composition according to the present invention, the content of sodium is 0.08% by weight or more and 0.5% by weight or less, in 100% by weight of the vinyl chloride resin composition.

Conventional vinyl chloride resin compositions have the problem of insufficient thermal stability. In addition, hydrogen chloride can corrode the metal surfaces of molds and the like, making long-term production difficult. Furthermore, depending on the amount of organotin stabilizer added, the heat resistance of the vinyl chloride resin composition can decrease.

The vinyl chloride resin composition according to the present invention has the above-mentioned configuration, and therefore the thermal stability during hot molding can be improved. As a result, the mechanical strength of the obtained molded body can be increased and discoloration of the molded body can be prevented. In addition, the vinyl chloride resin composition according to the present invention can suppress corrosion of the metal surface. For example, corrosion of the surface of the mold used for molding the vinyl chloride resin composition can be suppressed. As a result, vinyl chloride resin molded bodies can be produced over a long period of time. Furthermore, when the vinyl chloride resin composition and the obtained vinyl chloride resin molded body come into contact with metal, corrosion of the metal can be suppressed. Furthermore, the vinyl chloride resin composition according to the present invention can increase the heat resistance of the obtained molded body.

The vinyl chloride resin composition is preferably used to obtain a vinyl chloride resin molded article. The vinyl chloride resin composition is preferably used to obtain an injection-molded vinyl chloride resin molded article. The vinyl chloride resin composition is preferably injection molded. The vinyl chloride resin composition is preferably a vinyl chloride resin composition for injection molding.

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

<Vinyl chloride resin>
The vinyl chloride resin has a chlorine atom. The vinyl chloride resin may be a chlorinated vinyl chloride resin or a non-chlorinated vinyl chloride resin. From the viewpoint of improving heat resistance, the vinyl chloride resin is preferably a chlorinated vinyl chloride resin. The chlorinated vinyl chloride resin is a resin obtained by chlorinating a 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, copolymers of vinyl chloride monomers and vinyl monomers copolymerizable with vinyl chloride monomers, etc.

Examples of vinyl monomers copolymerizable with the vinyl chloride monomer include vinyl esters such as vinyl acetate, vinyl propionate, and vinyl ether; 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 methacrylate and ethyl methacrylate; and imide compounds such as maleimide. The vinyl monomers may be used alone or in combination of two or more.

The polymerization method of the vinyl chloride monomer or the polymerization method of the vinyl chloride monomer and the vinyl monomer is 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 vinyl chloride monomer and the vinyl monomer to obtain a vinyl chloride resin, and then chlorinating the vinyl chloride resin.

The method for chlorinating the vinyl chloride resin is not particularly limited. Examples of the method for 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 chlorine. This chlorination reaction proceeds under heating conditions or light irradiation conditions.

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

From the viewpoint of increasing the efficiency of the chlorination reaction, the temperature during the heating is preferably 80°C or higher and preferably 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 improved, and the impact resistance and surface smoothness of the resulting molded article can be 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, even more preferably 61.5% by weight or more, and preferably 72% by weight or less, more preferably 67.5% by weight or less. 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 article 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 improved, and the impact resistance and surface smoothness of the obtained molded article can be 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. If the degree of polymerization is equal to or greater than the lower limit, the mechanical strength of the molded body can be 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 improved.

In 100% by weight of the vinyl chloride resin composition, the content of the vinyl chloride resin is 80% by weight or more and 99% by weight or less. In 100% by weight of the vinyl chloride resin composition, the content of the vinyl chloride resin is preferably 85% by weight or more, more preferably 90% by weight or more, even more preferably 92% by weight or more, and preferably 98.5% by weight or less, more preferably 98% by weight or less, even more preferably 97% by weight or less. When the content of the vinyl chloride resin is equal to or more than the lower limit, the adhesive strength and mechanical strength of the molded product obtained can be increased. When the content of the vinyl chloride resin is equal to or less than the upper limit, it is not necessary to raise the temperature during molding, and moldability can be 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 improved. When the volume average particle diameter is equal to or less than the upper limit, the moldability can be 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 that inhibits decomposition of the vinyl chloride resin and captures hydrogen chloride generated during decomposition of the vinyl chloride resin.

The organotin stabilizer is preferably an organotin heat stabilizer.

The above-mentioned organic tin stabilizers include tin mercapto stabilizers, tin malate stabilizers, tin carboxylate stabilizers, etc. The above-mentioned tin mercapto stabilizers include monoalkyltin mercapto, dialkyltin mercapto, monoalkyltin mercapto polymer, dialkyltin mercapto polymer, monoalkyltin mercapto sulfide, dialkyltin mercapto sulfide, etc. The above-mentioned tin malate stabilizers include monoalkyltin malate, dialkyltin malate, monoalkyltin malate polymer, dialkyltin malate polymer, etc. The above-mentioned tin carboxylate stabilizers include monoalkyltin carboxylate, dialkyltin carboxylate, etc. The above-mentioned organic tin stabilizers may be used alone or in combination of two or more kinds.

From the viewpoint of further improving the thermal stability during hot molding and preventing initial coloring of the resulting molded body, the above-mentioned organotin stabilizer is preferably a tin mercapto stabilizer, preferably a dialkyltin mercapto, and more preferably dioctyltin mercapto.

The content of the organotin stabilizer in 100% by weight of the vinyl chloride resin composition is 0.1% by weight or more and 2.5% by weight or less. The content of the organotin stabilizer in 100% by weight of the vinyl chloride resin composition is preferably 0.5% by weight or more, more preferably 0.8% by weight or more, even more preferably 1.0% by weight or more, and preferably 2.4% by weight or less, more preferably 2.2% by weight or less, even more preferably 2.0% by weight or less. When the content of the organotin stabilizer is equal to or more than the lower limit and equal to or less than the upper limit, the thermal stability can be more effectively improved, and the heat resistance of the obtained molded body can be further improved.

The content of the organotin stabilizer relative to 100 parts by weight of the vinyl chloride resin in the vinyl chloride resin composition is preferably 0.5 parts by weight or more, more preferably 0.8 parts by weight or more, even more preferably 1.0 parts by weight or more, and preferably 2.4 parts by weight or less, more preferably 2.2 parts by weight or less, even more preferably 2.0 parts by weight or less. When the content of the organotin stabilizer is equal to or more than the lower limit and equal to or less than the upper limit, the thermal stability can be more effectively improved, and the heat resistance of the obtained molded body can be further improved.

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.

<Sodium Salt of Aliphatic Carboxylic Acid>
The vinyl chloride resin composition includes a sodium salt of an aliphatic carboxylic acid. The sodium salt of an aliphatic carboxylic acid includes sodium. Specifically, the sodium salt of an aliphatic carboxylic acid includes at least one sodium. The aliphatic 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 salts of the above aliphatic carboxylic acids neutralize the hydrogen chloride generated during the decomposition of vinyl chloride resin with sodium, thereby preventing hydrogen chloride from corroding the metal surfaces of molds and other devices. As a result, vinyl chloride resin molded articles can be produced over the long term.

Examples of the sodium salts of the above aliphatic carboxylic acids include disodium adipate, disodium sebacate, disodium azelaate, disodium suberate, and disodium pimelate. The above sodium salts of the aliphatic carboxylic acids may be used alone or in combination of two or more.

From the viewpoint of more effectively suppressing corrosion of the metal surface, the number of sodium atoms in the sodium salt of the aliphatic carboxylic acid is preferably more than one, and more preferably 2. The number of sodium atoms in the sodium salt of the aliphatic carboxylic acid may be 5 or less, 4 or less, or 3 or less.

From the viewpoint of improving the thermal stability during heat molding, the number of carbon atoms in the sodium salt of the above-mentioned 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 dispersion of the sodium salt of the aliphatic carboxylic acid and more effectively exerting the effects of the present invention, it is preferable that the number of COONa groups in the sodium salt of the aliphatic carboxylic acid is 2 and that the number of carbon atoms in the sodium salt of the aliphatic carboxylic acid is 6 or more and 16 or less. From the viewpoint of improving the thermal stability during hot molding, it is preferable that the sodium salt of the aliphatic carboxylic acid has a chain hydrocarbon skeleton with a carbon number of 2 or more and 14 or less.

Examples of the sodium salt of an aliphatic carboxylic acid having the above-mentioned preferred embodiment include disodium adipate, disodium sebacate, disodium azelaate, disodium suberate, and disodium pimelate. From the viewpoint of more effectively suppressing corrosion of the metal surface and improving the thermal stability during hot molding, it is particularly preferable that the sodium salt of the aliphatic carboxylic acid is disodium adipate.

In 100% by weight of the vinyl chloride resin composition, the content of the sodium salt of the aliphatic carboxylic acid is 0.1% by weight or more and 2.0% by weight or less. From the viewpoint of more effectively suppressing corrosion of the metal surface, in 100% by weight of the vinyl chloride resin composition, the content of the sodium salt of the aliphatic carboxylic acid is preferably 0.3% by weight or more, more preferably 0.7% by weight or more, even more preferably 1.0% by weight or more, and preferably 1.8% by weight or less, more preferably 1.6% by weight or less, even more preferably 1.5% by weight or less.

From the viewpoint of more effectively suppressing corrosion of the metal surface, the content of the sodium salt of the aliphatic carboxylic acid is preferably 0.3 parts by weight or more, more preferably 0.7 parts by weight or more, and even more preferably 1.0 parts by weight or more, and is preferably 1.8 parts by weight or less, more preferably 1.6 parts by weight or less, and even more preferably 1.5 parts by weight or less, per 100 parts by weight of the vinyl chloride resin in the vinyl chloride resin composition.

The sodium content in 100% by weight of the vinyl chloride resin composition is 0.08% by weight or more and 0.5% by weight or less. From the viewpoint of more effectively suppressing corrosion of the metal surface, the sodium content in 100% by weight of the vinyl chloride resin composition is preferably 0.10% by weight or more, more preferably 0.15% by weight or more, even more preferably 0.20% by weight or more, and preferably 0.45% by weight or less, more preferably 0.40% by weight or less, even more preferably 0.35% by weight or less. The sodium content in the resin composition can be measured using ICP emission spectrometry, ICP mass spectrometry, X-ray fluorescence spectrometry, etc.

The vinyl chloride resin composition may contain a compound containing sodium other than the sodium salt of the aliphatic carboxylic acid (hereinafter, may be referred to as compound (A)). In the vinyl chloride resin composition, a compound other than the sodium salt of the aliphatic carboxylic acid may contain sodium.

Case (1) refers to the case where the sodium contained in the vinyl chloride resin composition is only sodium derived from the sodium salt of the aliphatic carboxylic acid. In case (1), the sodium content in 100% by weight of the vinyl chloride resin composition indicates the sodium content derived from the sodium salt of the aliphatic carboxylic acid. Case (2) refers to the case where the sodium contained in the vinyl chloride resin composition is both sodium derived from the sodium salt of the aliphatic carboxylic acid and sodium derived from the compound (A). In case (2), the sodium content in 100% by weight of the vinyl chloride resin composition indicates the sum of the sodium content derived from the sodium salt of the aliphatic carboxylic acid and the sodium content derived from the compound (A).

<Inorganic filler>
The vinyl chloride resin composition does not contain an inorganic filler or contains an inorganic filler. The vinyl chloride resin composition may not contain an inorganic filler or may contain an inorganic filler.

Examples of the inorganic filler include calcium carbonate, silica, talc, titanium oxide, zinc oxide, magnesium oxide, aluminum hydroxide, magnesium hydroxide, clay, mica, wollastonite, zeolite, carbon black, graphite, glass beads, glass fibers, hydrocarbons, and metal fibers. From the viewpoint of improving the appearance of the vinyl chloride resin composition and the resulting molded article and increasing the mechanical strength of the resulting molded article, it is preferable that the inorganic filler is calcium carbonate. Only one type of the inorganic filler may be used, or two or more types may be used in combination.

The inorganic filler is preferably an inorganic particle. The aspect ratio of the inorganic filler is preferably 2.0 or less, more preferably 1.5 or less, and even more preferably 1.2 or less.

When the vinyl chloride resin composition contains the inorganic filler, the content of the inorganic filler in 100% by weight of the vinyl chloride resin composition is preferably 2% by weight or more, more preferably 4% by weight or more, and preferably 30% by weight or less, more preferably 20% by weight or less, and even more preferably 15% by weight or less. When the content of the inorganic filler is equal to or greater than the lower limit, the mechanical strength of the obtained molded body can be increased. When the content of the inorganic filler is equal to or less than the upper limit, the appearance of the vinyl chloride resin composition and the obtained molded body can be improved. The content of the inorganic filler may be 0% by weight (unused). It is particularly preferable that the vinyl chloride resin composition does not contain an inorganic filler or contains 15% by weight or less of an inorganic filler in 100% by weight of the vinyl chloride resin composition.

The content of the inorganic filler is preferably 2 parts by weight or more, more preferably 4 parts by weight or more, and preferably 30 parts by weight or less, more preferably 20 parts by weight or less, and even more preferably 15 parts by weight or less, relative to 100 parts by weight of the vinyl chloride resin. When the content of the inorganic filler is equal to or more than the lower limit, the mechanical strength of the obtained molded article can be increased. When the content of the inorganic filler is equal to or less than the upper limit, the appearance of the vinyl chloride resin composition and the obtained molded article can be improved. The content of the inorganic filler may be 0% by weight (unused).

The particle diameter of the inorganic filler is preferably 10 nm or more, and preferably 3 μm or less. The particle diameter of the inorganic filler is preferably an average particle diameter, and preferably a number average particle diameter. The particle diameter of the inorganic filler is, for example, obtained by observing 50 arbitrary inorganic fillers with an electron microscope or an optical microscope and calculating the average particle diameter of each inorganic filler, or by using a particle size distribution measuring device. In the observation with an electron microscope or an optical microscope, the particle diameter of each inorganic filler is obtained as a particle diameter of a circle equivalent diameter. In the observation with an electron microscope or an optical microscope, the average particle diameter of 50 arbitrary inorganic fillers with a circle equivalent diameter is almost equal to the average particle diameter of the sphere equivalent diameter. In the particle size distribution measuring device, the particle diameter of each inorganic filler is obtained as a particle diameter of a sphere equivalent diameter. The average particle diameter of the inorganic filler is preferably calculated using a particle size distribution measuring device.

<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, antioxidants, UV absorbers, antistatic agents, light stabilizers, fillers, pigments, flame retardants, 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, and specific examples thereof 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 antioxidant is not particularly limited, and examples thereof include phenol-based antioxidants. The antioxidants may be used alone or in combination of two or more.

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.

(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 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 vinyl chloride resin molded body is not particularly limited, and examples thereof 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. The plate-like vinyl chloride resin molded body includes a sheet-like and a film-like shape.

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. From the viewpoint of more effectively suppressing corrosion of the metal surface, the molding method of the vinyl chloride resin composition is preferably an injection molding method with a long residence time.

The vinyl chloride resin molded body is preferably an injection molded body.

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 for forming, the resin temperature, etc.

The present invention will be described in more detail below with reference to examples. The present invention is not limited to the following examples.

The following materials were prepared:

(Vinyl chloride resin)
Vinyl chloride resin (Tokuyama Sekisui Kogyo Co., Ltd. "TS-1000R", chlorine content 56.8% by weight, polymerization degree 1000)

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

(Sodium salts of aliphatic carboxylic acids)
A (disodium adipate, manufactured by TCI, sodium number: 2, carbon number: 6)
B (sodium myristate, manufactured by TCI, sodium number: 1, carbon number: 14)

(Inorganic filler)
Calcium carbonate ("Whiten SB" manufactured by Shiraishi Calcium Co., Ltd.)

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

(Examples 1 , 2, 4, 5, Reference Examples 3, 6, 7, and Comparative Examples 1 to 7)
The types and amounts of the ingredients were 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 190°C. The test sample A was visually checked for the presence or absence of blackening, and the time until the onset of blackening was measured at 10-minute intervals. The thermal stability was evaluated according to the following criteria.

[Criteria for thermal stability]
○○: More than 100 minutes until blackening begins ○: More than 80 minutes and 100 minutes or less until blackening begins ×: Less than 80 minutes until blackening begins

(2) Metal Corrosion Inhibition Effect The obtained sheet was pressed under the following conditions.

[conditions]
Press: Toho Machinery 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 size: thickness 3.0 mm x length 200 mm x width 200 mm

After pressing, the press surface of the hot press molding machine was visually inspected. The presence or absence of corrosion due to hydrochloric acid on the press surface (mold) was judged according to the following criteria.

[Metal corrosion inhibition]
○: The pressed surface is not discolored (not corroded).
×: The pressed surface has turned white (corroded).

(3) Heat Resistance of Molded Product The obtained sheet was pressed under the following conditions.

[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 size: thickness 3.0 mm x length 200 mm x width 200 mm

After pressing, the test sample B (molded body) was obtained by cutting into a size of 30 mm in length and 30 mm in width. The Vicat softening temperature of the test sample B was measured in accordance with JIS K7206. The heat resistance of the test sample B (molded body) was evaluated according to the following criteria.

[Heat resistance of molded product]
○○: Vicat softening temperature is 82°C or higher. ○: Vicat softening temperature is 79°C or higher but less than 82°C. ×: Vicat softening temperature is less than 79°C.

The compounding compositions and results are shown in Tables 1 and 2 below. In Tables 1 and 2, the content expressed in "weight %" indicates the content in 100 weight % of the vinyl chloride resin composition.

Claims (5)

A vinyl chloride resin composition comprising a vinyl chloride resin, an organotin stabilizer, and a sodium salt of an aliphatic carboxylic acid,
the sodium salt of an aliphatic carboxylic acid is disodium adipate;
the content of the vinyl chloride resin is 80% by weight or more and 99% by weight or less, the content of the organotin stabilizer is 0.1% by weight or more and 2.5% by weight or less, and the content of the sodium salt of the aliphatic carboxylic acid is 0.1% by weight or more and 1.0% by weight or less, based on 100 % by weight of the vinyl chloride resin composition;
The vinyl chloride resin composition, wherein the sodium content is 0.08% by weight or more and 0.24 % by weight or less based on 100% by weight of the vinyl chloride resin composition. 2. The vinyl chloride resin composition according to claim 1 , wherein the organotin stabilizer is a tin mercapto stabilizer. 3. The vinyl chloride resin composition according to claim 1, which does not contain an inorganic filler or contains an inorganic filler in an amount of 15% by weight or less based on 100% by weight of the vinyl chloride resin composition. The vinyl chloride resin composition according to any one of claims 1 to 3 , which is a vinyl chloride resin composition for injection molding. 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 4 .