JP7689841B2 - Vinyl chloride resin composition and joint - Google Patents

Description

The present invention relates to a vinyl chloride resin composition containing a vinyl chloride resin and a joint 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 joints, pipes, plates, and containers, and are used in many fields.

When producing vinyl chloride resin compositions and vinyl chloride resin molded articles, additives such as stabilizers and lubricants are sometimes used to improve moldability. However, stabilizers and lubricants are relatively expensive, which increases the production costs. Therefore, inexpensive calcium carbonate is sometimes used as a filler to reduce the production costs of vinyl chloride resin compositions and vinyl chloride resin molded articles.

The following Patent Document 1 discloses a vinyl chloride resin composition containing a vinyl chloride resin and cubic calcium carbonate. The vinyl chloride resin composition preferably contains a plasticizer.

Patent Document 2 below discloses a rigid polyvinyl chloride molded product that contains 100 parts by mass of a polyvinyl chloride resin with an average degree of polymerization of 500 to 1500 and 10 to 40 parts by mass of calcium carbonate. The calcium carbonate has an average primary particle size of 0.01 μm to 0.3 μm and a coefficient of variation in the number of particles of 15% or less.

JP 2002-167486 A JP 2019-038996 A

In Patent Documents 1 and 2, the production costs can be reduced to some extent by adding calcium carbonate to a vinyl chloride resin composition.

However, due to poor compatibility between calcium carbonate and vinyl chloride resin, the calcium carbonate particles pulverized by mixing with vinyl chloride resin are difficult to disperse uniformly in the vinyl chloride resin composition, and tend to aggregate into secondary particles in the composition or during molding. If secondary particles of calcium carbonate are present in a vinyl chloride resin molded body, the appearance of the molded body may deteriorate, for example, causing unevenness on the surface or loss of gloss. This problem is more pronounced in injection molding, which has a lower kneading capacity than extrusion molding.

Furthermore, the vinyl chloride resin composition described in Patent Document 1 has the problem that the heat resistance and impact resistance of the vinyl chloride resin are reduced by the plasticizer. In addition, calcium carbonate reduces the flowability of the vinyl chloride resin composition during molding, and the resin composition may not be able to be sufficiently filled into the mold.

In addition, the primary particle size of the calcium carbonate used in Patent Document 2 is too small, so the calcium carbonate is more likely to aggregate and more likely to form secondary particles of calcium carbonate. As a result, there is a problem that the appearance of the obtained vinyl chloride resin molded article is further deteriorated.

The object of the present invention is to provide a vinyl chloride resin composition that can increase the flowability during molding and improve the appearance of the resulting molded article. Another object of the present invention is to provide a joint 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 acrylic resin having a weight-average molecular weight of 100,000 or more and 500,000 or less, and calcium carbonate, wherein the content of the acrylic resin is 0.5 parts by weight or more and 6 parts by weight or less and the content of the calcium carbonate is 0.5 parts by weight or more and 15 parts by weight or less, relative to 100 parts by weight of the vinyl chloride resin, the vinyl chloride resin composition contains secondary particles of the calcium carbonate, and the average particle size of the secondary particles of the calcium carbonate is 0.1 μm or more and 15 μm or less.

In a specific aspect of the vinyl chloride resin composition according to the present invention, the vinyl chloride resin composition does not contain a polyethylene lubricant, or contains a polyethylene lubricant in an amount of 2 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 vinyl chloride resin composition contains a polyethylene lubricant, and the acid value of the polyethylene lubricant is 10 or more and 30 or less.

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, a joint is provided that is obtained by molding the vinyl chloride resin composition described above.

The vinyl chloride resin composition according to the present invention contains a vinyl chloride resin, an acrylic resin having a weight-average molecular weight of 100,000 or more and 500,000 or less, and calcium carbonate. In the vinyl chloride resin composition according to the present invention, the content of the acrylic resin is 0.5 parts by weight or more and 6 parts by weight or less, and the content of the calcium carbonate is 0.5 parts by weight or more and 15 parts by weight or less, relative to 100 parts by weight of the vinyl chloride resin. The vinyl chloride resin composition according to the present invention contains secondary particles of the calcium carbonate, and the average particle diameter of the secondary particles of the calcium carbonate is 0.1 μm or more and 15 μm or less. Since the vinyl chloride resin composition according to the present invention has the above-mentioned configuration, it is possible to increase the flowability during molding and improve the appearance 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 acrylic resin having a weight-average molecular weight of 100,000 or more and 500,000 or less, and calcium carbonate. In the vinyl chloride resin composition, the content of the acrylic resin is 0.5 parts by weight or more and 6 parts by weight or less, and the content of the calcium carbonate is 0.5 parts by weight or more and 15 parts by weight or less, relative to 100 parts by weight of the vinyl chloride resin. The vinyl chloride resin composition according to the present invention contains secondary particles of the calcium carbonate, and the average particle size of the secondary particles of the calcium carbonate is 0.1 μm or more and 15 μm or less.

The vinyl chloride resin composition according to the present invention has the above-mentioned configuration, and therefore can enhance the fluidity during molding. As a result, the vinyl chloride resin composition can be sufficiently filled into the mold during molding. Furthermore, the appearance of the obtained molded article can be improved. In addition, the vinyl chloride resin composition according to the present invention contains calcium carbonate at a specific content, and therefore the manufacturing cost can be reduced.

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.

In this specification, a single unagglomerated calcium carbonate in the material of the vinyl chloride resin composition is referred to as a primary particle of calcium carbonate. Crushed particles of the primary particles of calcium carbonate are referred to as crushed particles of calcium carbonate. Aggregates of two or more primary particles or crushed particles of calcium carbonate are referred to as secondary particles of calcium carbonate.

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

In this specification, "(meth)acrylic" means either or both of "acrylic" and "methacrylic", and "(meth)acrylate" means either or both of "acrylate" and "methacrylate".

<Vinyl chloride resin>
The vinyl chloride resin has a chlorine atom. The vinyl chloride resin may be a chlorinated vinyl chloride resin, a non-chlorinated vinyl chloride resin, or a mixture of a chlorinated vinyl chloride resin and a non-chlorinated vinyl chloride resin. From the viewpoint of improving the heat deformation 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; (meth)acrylic acid esters such as methyl (meth)acrylate and ethyl (meth)acrylate; 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 a vinyl monomer copolymerizable with the vinyl chloride 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 65°C or higher and preferably 130°C or lower.

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 1100 or less, and even more preferably 1000 or less. When the degree of polymerization is equal to or greater than the lower limit, the impact resistance and durability of the molded article can be improved. When the degree of polymerization is equal to or less than the upper limit, the melt viscosity of the vinyl chloride resin and the vinyl chloride resin composition can be reduced, thereby improving the flowability during molding.

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 87% by weight or more, even more preferably 90% by weight or more, and preferably 95% by weight or less, more preferably 92% by weight or less, even more preferably 91% 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 impact resistance of the obtained molded article 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 particle diameter of the vinyl chloride resin particles is preferably 0.1 μm or more and preferably 500 μm or less. If the particle diameter is equal to or more than the lower limit, the handling properties can be improved. If the particle diameter is equal to or less than the upper limit, the moldability can be improved.

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

<Acrylic resin>
The vinyl chloride resin composition contains an acrylic resin having a weight average molecular weight of 100,000 or more and 500,000 or less. Since the vinyl chloride resin composition has the above-mentioned configuration, the calcium carbonate can be uniformly dispersed in the vinyl chloride resin composition, and the melt viscosity can be reduced. As a result, the flowability during molding can be increased, and the appearance of the obtained molded product can be improved.

From the viewpoint of exerting the effects of the present invention more effectively, the weight average molecular weight of the acrylic resin is preferably 150,000 or more, more preferably 200,000 or more, and is preferably 450,000 or less, more preferably 400,000 or less.

The weight average molecular weight of the acrylic resin can be measured by gel permeation chromatography (GPC) or size exclusion chromatography.

In gel permeation chromatography (GPC) measurements, the weight average molecular weight is measured in terms of a standard sample. Examples of the standard sample include polystyrene, polymethyl methacrylate, and polyethylene glycol. For example, to measure the weight average molecular weight in terms of polystyrene, GPC measurements are performed on a polystyrene standard sample with a known molecular weight.

When using a polystyrene standard sample as the standard sample, nine samples with the following weight average molecular weights are used as the polystyrene standard sample (Shodex Standard SM-105 manufactured by Showa Denko K.K.). Standard sample No. (weight average molecular weight) for each sample: S-1.3 (1270), S-3.2 (3180), S-6.9 (6,940), S-22 (21,800), S-53 (52,500), S-333 (333,000), S-609 (609,000), S-1345 (1,350,000), S-2704 (2,700,000).

The molecular weight is plotted against the elution time indicated by the peak top of each standard sample peak, and the obtained approximate straight line is used as a calibration curve. The acrylic resin may be dissolved in tetrahydrofuran (THF) to prepare a 0.2 wt% solution, and the solution may be analyzed by a GPC device using tetrahydrofuran (THF) as the eluent to measure the weight average molecular weight. If the acrylic resin has an amide group, it may be dissolved in dimethylformamide or N-methylpyrrolidone instead of tetrahydrofuran (THF) to prepare a 0.2 wt% solution. In this case, dimethylformamide containing lithium bromide or N-methylpyrrolidone containing lithium bromide may be used as the eluent. Examples of GPC devices include Waters' "RI: 2414 (autosampler alliance: e2695, guard column: KF-G, column: two Shodex KF806L in series)".

Examples of the acrylic resin include a homopolymer of an acrylic monomer, a copolymer of an acrylic monomer and a monomer copolymerizable with the acrylic monomer, and the like. Only one type of the acrylic resin may be used, or two or more types may be used in combination.

Examples of the acrylic monomer include (meth)acrylic acid and (meth)acrylic acid esters. Examples of the (meth)acrylic acid esters include ethyl (meth)acrylate, methyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-amyl (meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and n-octyl (meth)acrylate.

Examples of monomers that can be copolymerized with the acrylic monomers include vinyl monomers, diene monomers, styrene monomers, and unsaturated dicarboxylic acid diesters. In this specification, a copolymer of a vinyl chloride monomer and an acrylic monomer is considered to be a vinyl chloride resin, and is not considered to be an acrylic resin.

The content of the acrylic resin is 0.5 parts by weight or more and 6 parts by weight or less per 100 parts by weight of the vinyl chloride resin. From the viewpoint of more effectively exerting the effects of the present invention, the content of the acrylic resin is preferably 0.7 parts by weight or more, more preferably 1 part by weight or more, and preferably 5 parts by weight or less, more preferably 3 parts by weight or less per 100 parts by weight of the vinyl chloride resin.

In order to more effectively exert the effects of the present invention, the content of the acrylic resin in 100% by weight of the vinyl chloride resin composition is preferably 0.6% by weight or more, more preferably 0.9% by weight or more, and is preferably 4% by weight or less, more preferably 3% by weight or less.

<Calcium carbonate>
In the vinyl chloride resin composition, the calcium carbonate acts as a filler. The vinyl chloride resin composition contains secondary particles of the calcium carbonate.

In the material of the vinyl chloride resin composition, the calcium carbonate is preferably present as primary particles. The primary particles of calcium carbonate may be pulverized into two or more particles by mixing with the vinyl chloride resin or the like during preparation of the vinyl chloride resin composition to become pulverized particles. The pulverized particles of calcium carbonate are formed by pulverizing the primary particles of calcium carbonate. The primary particles and pulverized particles of calcium carbonate may aggregate in the vinyl chloride resin composition and during molding to become secondary particles. The secondary particles of calcium carbonate are formed by two or more primary particles or pulverized particles of calcium carbonate. The secondary particles of calcium carbonate may be formed only by the primary particles of calcium carbonate, may be formed only by the pulverized particles of calcium carbonate, or may be formed by a combination of the primary particles and pulverized particles of calcium carbonate.

The vinyl chloride resin composition may contain primary particles of the calcium carbonate, may contain crushed particles of the calcium carbonate, or may contain primary particles and crushed particles of the calcium carbonate. The vinyl chloride resin composition preferably contains crushed particles of the calcium carbonate. The calcium carbonate in the vinyl chloride resin composition is preferably crushed particles of the calcium carbonate. In the vinyl chloride resin composition, the calcium carbonate is preferably present as crushed particles. It is preferable that the calcium carbonate is not aggregated in the vinyl chloride resin composition.

From the viewpoint of exerting the effects of the present invention more effectively, the particle diameter (primary particle diameter) of the primary particles of the calcium carbonate is preferably 0.5 μm or more, more preferably 0.8 μm or more, even more preferably 1.5 μm or more, and is preferably 20 μm or less, more preferably 18 μm or less, even more preferably 15 μm or less.

The particle diameter (crushed particle diameter) of the crushed particles of the calcium carbonate is preferably 0.05 μm or more, more preferably 0.1 μm or more, even more preferably 0.2 μm or more, particularly preferably 0.5 μm or more, and preferably 5.0 μm or less, more preferably 3.0 μm or less, even more preferably 2.0 μm or less, particularly preferably 1.0 μm or less. When the particle diameter of the crushed particles of the calcium carbonate is equal to or greater than the lower limit, the specific surface area of the crushed particles of the calcium carbonate can be reduced, so that the aggregation of the crushed particles of the calcium carbonate can be suppressed, and the particle diameter of the secondary particles of the calcium carbonate can be reduced. As a result, the impact resistance of the resulting molded body can be improved. When the particle diameter of the crushed particles of the calcium carbonate is equal to or less than the upper limit, the particle diameter of the secondary particles of the calcium carbonate can be reduced. As a result, the impact resistance of the resulting molded body can be improved.

The particle diameter (secondary particle diameter) of the secondary particles of the calcium carbonate in the vinyl chloride resin composition is 0.1 μm or more and 15 μm or less. From the viewpoint of exerting the effects of the present invention more effectively, the particle diameter (secondary particle diameter) of the secondary particles of the calcium carbonate in the vinyl chloride resin composition is preferably 0.5 μm or more, more preferably 1.5 μm or more, and preferably 14 μm or less, more preferably 10 μm or less.

The primary particle size, crushed particle size, and secondary particle size of the calcium carbonate are preferably average particle sizes, and are preferably number average particle sizes. The particle size of the calcium carbonate is determined, for example, by observing 50 arbitrary calcium carbonate particles with an electron microscope or optical microscope and calculating the average particle size of each calcium carbonate, or by using a particle size distribution measuring device. In the observation with an electron microscope or optical microscope, the particle size of each calcium carbonate particle is determined as the particle size of a circle equivalent diameter. In the observation with an electron microscope or optical microscope, the average particle size of 50 arbitrary calcium carbonate particles with a circle equivalent diameter is almost equal to the average particle size of the sphere equivalent diameter. In the particle size distribution measuring device, the particle size of each calcium carbonate particle is determined as the particle size of a sphere equivalent diameter. The average particle size of the calcium carbonate is preferably calculated using a particle size distribution measuring device.

The primary particles, crushed particles, and secondary particles of the calcium carbonate may be spherical or may have a shape other than spherical, such as a square prism, a cylinder, or a flat shape. From the viewpoint of further increasing the fluidity during molding, the primary particles, crushed particles, and secondary particles of the calcium carbonate are preferably spherical. The aspect ratios of the primary particles, crushed particles, and secondary particles of the calcium carbonate are preferably 2.0 or less, more preferably 1.5 or less, and even more preferably 1.2 or less.

The content of the calcium carbonate is 0.5 parts by weight or more and 15 parts by weight or less per 100 parts by weight of the vinyl chloride resin. Since the present invention has the above configuration, it is possible to increase the fluidity during molding and improve the appearance of the obtained molded body. In addition, it is possible to reduce the production cost of the vinyl chloride resin composition. From the viewpoint of further reducing the production cost and more effectively exerting the effects of the present invention, the content of the calcium carbonate is preferably 0.8 parts by weight or more, more preferably 1 part by weight or more, and preferably 10 parts by weight or less, more preferably 5 parts by weight or less per 100 parts by weight of the vinyl chloride resin.

From the viewpoint of further reducing the manufacturing cost and more effectively exerting the effects of the present invention, the content of the calcium carbonate is preferably 0.7% by weight or more, more preferably 0.9% by weight or more, and is preferably 9% by weight or less, more preferably 5% by weight or less, based on 100% by weight of the vinyl chloride resin composition.

<Other Ingredients>
The vinyl chloride resin composition may contain various additives as necessary. Examples of the additives include stabilizers, thermal stabilization assistants, lubricants, impact modifiers, heat resistance improvers, antioxidants, ultraviolet absorbers, antistatic agents, light stabilizers, pigments, flame retardants, and plasticizers. The additives may be used alone or in combination of two or more.

The vinyl chloride resin composition preferably contains a stabilizer. Examples of the stabilizer include an organotin stabilizer, a lead stabilizer, a calcium-zinc stabilizer, and a barium-zinc stabilizer. The stabilizers may be used alone or in combination of two or more.

The stabilizer is preferably a heat stabilizer.

From the viewpoint of suppressing the decomposition of the vinyl chloride resin and capturing the hydrochloric acid generated during the decomposition of the vinyl chloride resin, the vinyl chloride resin composition preferably contains an organotin stabilizer, and more preferably contains an organotin heat stabilizer. Furthermore, the use of an organotin stabilizer further improves the appearance of the resulting molded article.

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 improving the appearance of the resulting molded article, the above-mentioned organotin stabilizer is preferably a tin mercapto stabilizer, preferably a dialkyltin mercapto, and more preferably dioctyltin mercapto or dimethyltin mercapto.

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.

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 0.2 parts by weight or more, more preferably 0.3 parts by weight or more, even more preferably 0.4 parts by weight or more, and is preferably 3.0 parts by weight or less, more preferably 2.0 parts by weight or less, even more preferably 1.5 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 improved, and the heat resistance of the obtained molded body can be improved.

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 vinyl chloride resin composition may or may not contain a lubricant. It is preferable that the vinyl chloride resin composition contains a lubricant.

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 polyethylene-based lubricants, ester-based lubricants, paraffin wax, polyolefin wax, and montanic acid wax. Only one type of the lubricants may be used, or two or more types may be used in combination.

From the viewpoint of improving the sliding property between the molten resin and the metal surface during molding, the vinyl chloride resin composition preferably contains a polyethylene lubricant, and more preferably contains a polyethylene lubricant and an ester lubricant. In the present invention, the vinyl chloride resin, the specific acrylic resin, and the specific calcium carbonate are used in specific contents, so that the appearance can be improved. Therefore, the content of the polyethylene lubricant in the vinyl chloride resin composition may be small, and the vinyl chloride resin composition may not contain a polyethylene lubricant.

The acid value of the polyethylene lubricant is preferably 5 or more, more preferably 10 or more, and even more preferably 15 or more, and is preferably 50 or less, more preferably 40 or less, and even more preferably 30 or less. When the acid value of the polyethylene lubricant is equal to or more than the lower limit, the calcium carbonate can be uniformly dispersed in the vinyl chloride resin composition. As a result, the flowability during molding can be increased and the appearance of the obtained molded article can be improved. When the acid value of the polyethylene lubricant is equal to or less than the upper limit, the sliding between the vinyl chloride resin composition and the metal surface (mold) during molding can be improved, and the appearance of the obtained molded article can be further improved.

It is preferable that the vinyl chloride resin composition does not contain a polyethylene-based lubricant or contains a polyethylene-based lubricant in a content of 10 parts by weight or less per 100 parts by weight of the vinyl chloride resin. When the vinyl chloride resin composition contains the polyethylene-based lubricant, it is preferable to satisfy the following content. The content of the polyethylene-based lubricant is preferably more than 0 parts by weight, more preferably 0.1 parts by weight or more, even more preferably 0.5 parts by weight or more, and preferably 2.0 parts by weight or less, more preferably 1.5 parts by weight or less, and even more preferably 1.0 parts by weight or less per 100 parts by weight of the vinyl chloride resin. When the content of the polyethylene-based lubricant satisfies the above lower limit and the above upper limit, the calcium carbonate can be uniformly dispersed in the vinyl chloride resin composition. As a result, the fluidity during molding can be increased and the appearance of the obtained molded body can be made even better. In addition, the sliding between the vinyl chloride resin composition and the metal surface (mold) during molding can be improved, and the appearance of the obtained molded body can be made even better.

In the present invention, the vinyl chloride resin, the specific acrylic resin, and the specific calcium carbonate are used in specific contents, so that the appearance can be improved. Therefore, the content of the ester-based lubricant in the vinyl chloride resin composition may be small, and the vinyl chloride resin composition may not contain an ester-based lubricant. It is preferable that the vinyl chloride resin composition does not contain both a polyethylene-based lubricant and an ester-based lubricant, or contains at least one of the polyethylene-based lubricant and the ester-based lubricant in a total content of 2 parts by weight or less per 100 parts by weight of the vinyl chloride resin. When the vinyl chloride resin composition contains at least one of the polyethylene-based lubricant and the ester-based lubricant, it is preferable to satisfy the following content. The total content of the polyethylene-based lubricant and at least one of the ester-based lubricants per 100 parts by weight of the vinyl chloride resin is preferably more than 0 parts by weight, more preferably 0.2 parts by weight or more, and even more preferably 0.4 parts by weight or more. The total content of at least one of the polyethylene-based lubricant and the ester-based lubricant is preferably 1.5 parts by weight or less, more preferably 1.0 parts by weight or less, and even more preferably 0.6 parts by weight or less, relative to 100 parts by weight of the vinyl chloride resin. When the total content of at least one of the polyethylene-based lubricant and the ester-based lubricant satisfies the lower limit and the upper limit, the calcium carbonate can be uniformly dispersed in the vinyl chloride resin composition. As a result, the flowability during molding can be increased and the appearance of the molded product obtained can be improved. In addition, the sliding between the vinyl chloride resin composition and the metal surface (mold) during molding can be improved, and the appearance of the molded product obtained can be improved.

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 resins 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 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 body according to the present invention is a vinyl chloride resin molded body obtained by molding a vinyl chloride resin composition containing a vinyl chloride resin, an acrylic resin having a weight-average molecular weight of 100,000 or more and 500,000 or less, and calcium carbonate. In the vinyl chloride resin molded body according to the present invention, the vinyl chloride resin composition contains 0.5 parts by weight or more and 6 parts by weight or less of the acrylic resin and contains 0.5 parts by weight or more and 15 parts by weight or less of the calcium carbonate, relative to 100 parts by weight of the vinyl chloride resin. The vinyl chloride resin molded body contains secondary particles of the calcium carbonate. In the vinyl chloride resin molded body, the average particle size of the secondary particles of the calcium carbonate is 0.1 μm or more and 15 μm or less.

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

In the vinyl chloride resin molded body, the primary particles and crushed particles of the calcium carbonate can be uniformly dispersed. As a result, the appearance of the vinyl chloride resin molded body can be improved.

In addition, a part of the primary particles and pulverized particles of the calcium carbonate in the vinyl chloride resin composition may aggregate in the composition or during molding. In the vinyl chloride resin molded body, a part of the primary particles and pulverized particles of the calcium carbonate aggregate. The vinyl chloride resin molded body contains secondary particles of the calcium carbonate. In the vinyl chloride resin molded body, primary particles, pulverized particles, and secondary particles of the calcium carbonate may be present. The vinyl chloride resin molded body may contain only secondary particles of the calcium carbonate, may contain primary particles and secondary particles, may contain pulverized particles and secondary particles, or may contain primary particles, pulverized particles, and secondary particles.

The particle diameter (secondary particle diameter) of the secondary particles of the calcium carbonate in the vinyl chloride resin molded body is 0.1 μm or more and 15 μm or less. The particle diameter of the secondary particles of the calcium carbonate in the vinyl chloride resin molded body is preferably 0.5 μm or more, more preferably 1.5 μm or more, and preferably 14 μm or less, more preferably 10 μm or less, even more preferably 8.0 μm or less, and particularly preferably 5.0 μm or less. When the particle diameter of the secondary particles of the calcium carbonate is equal to or more than the above lower limit and equal to or less than the above upper limit, the appearance of the molded body can be further improved and the impact resistance can be increased.

The particle size of the secondary particles of calcium carbonate in the vinyl chloride resin molded body is preferably an average particle size, and is preferably a number average particle size. The particle size of the secondary particles of calcium carbonate can be measured, for example, by the following method. The vinyl chloride resin molded body is cut using a diamond cutter, and the cut surface is polished. The cross section is observed using a scanning electron microscope, and the average particle size of the secondary particles of calcium carbonate present in a unit area is determined using image analysis software. An example of the diamond cutter is the "Circular Saw Model 2711" manufactured by Makita Corporation.

For example, if one secondary particle is composed of three primary particles of calcium carbonate, the number of primary particles of calcium carbonate that are secondary particles in this secondary particle is counted as 3. For example, if one secondary particle is composed of three pulverized particles of calcium carbonate, the number of pulverized particles of calcium carbonate that are secondary particles in this secondary particle is counted as 3.

The vinyl chloride resin molded article is not particularly limited, and examples include fittings, pipes, plates, and containers.

The vinyl chloride resin molded article is preferably a joint, since it can reduce manufacturing costs, further increase fluidity during molding, improve appearance, and increase durability. The joint is obtained by molding the vinyl chloride resin composition. The joint according to the present invention can reduce manufacturing costs, further increase fluidity during molding, improve appearance, and increase durability.

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 further increasing the fluidity during molding, the molding method of the vinyl chloride resin composition is preferably injection molding.

The vinyl chloride resin molded article is preferably an injection molded article. The vinyl chloride resin molded article is preferably an injection molded article of the vinyl chloride resin composition.

The molding machine used for molding is not particularly limited, and examples include a screw-type injection molding machine, 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-640M", polymerization degree: 640)

(Acrylic resin)
Acrylic resin 1 ("Metablen P-570A" manufactured by Mitsubishi Chemical Corporation, weight average molecular weight: 250,000)
Acrylic resin 2 (Kaneka Corporation "PA-30", weight average molecular weight: 3 million)

(Calcium Carbonate)
Calcium carbonate 1 ("Nanocoat S-25" manufactured by Maruo Calcium Co., Ltd., average particle size of primary particles: 0.8 μm)
Calcium carbonate 2 (Shiraishi Kogyo Co., Ltd. "Whiten 306", average particle size of primary particles 12 μm)
Calcium carbonate 3 (Shiraishi Kogyo Co., Ltd. "ST Powder H50", average particle size of primary particles: 22 μm)

(Lubricant)
Polyethylene-based lubricant 1 ("HW2203A" manufactured by Mitsui Chemicals, Inc., acid value: 30)
Polyethylene-based lubricant 2 ("HW220MP" manufactured by Mitsui Chemicals, Inc., acid value: 1)
Ester lubricant (Emery Oleo's "G15")

(Stabilizer)
Organotin stabilizer ("TVS#1500" manufactured by Nitto Kasei Kogyo Co., Ltd.)

(Examples 1 to 4, Examples 6 to 12, Reference Example 5 , and Comparative Examples 1 to 8)
The types and amounts of the ingredients were added to a rotary mixer (Kawata Corporation's "20L Super Mixer") as shown in Tables 1 to 3 below, and steam was added to perform rotary mixing at a rotation speed of 1500 rpm and the temperature was raised to 105° C. Next, the steam was stopped, cooling water was turned on to perform rotary mixing, and the mixture was cooled to obtain a vinyl chloride resin composition.

The obtained vinyl chloride resin composition was used in a screw-type injection molding machine (a 100 ton injection molding machine manufactured by JSW) and a bar flow mold to obtain a spiral vinyl chloride resin molded body having a thickness of 1 mm and a width of 10 mm.

(evaluation)
(1) Average particle diameter of secondary particles of calcium carbonate The obtained vinyl chloride resin molded body (joint) was cut into a length of 3 mm using a diamond cutter (Makita Corporation, "Circular Saw Model 2711"), and the cross section was observed using a scanning electron microscope (JEOL Corporation, "JSM-6510A"). Using image analysis software (ImageJ), the average circle equivalent diameter of secondary particles of calcium carbonate present in any 1 ^cm2 was calculated, and this was taken as the average particle diameter of the secondary particles (secondary particle diameter).

(2) Fluidity during molding The length of the spiral shape (bar flow length) of the obtained vinyl chloride resin molded article was measured. The fluidity of the vinyl chloride resin composition during molding was evaluated according to the following criteria.

[Criteria for determining fluidity during molding]
○○: Bar flow length is 85 mm or more. ○: Bar flow length is 75 mm or more and less than 85 mm. △: Bar flow length is 56 mm or more and less than 75 mm. ×: Bar flow length is less than 56 mm.

(3) Appearance of Molded Article The vinyl chloride resin molded article obtained was visually observed and the appearance of the molded article was judged according to the following criteria.

[Criteria for judging the appearance of molded products]
○○: Overall, the surface is very glossy and has a good appearance. ○: Overall, the surface is glossy and has a somewhat good appearance. △: The surface is glossy in some areas and has a somewhat poor appearance. ×: The surface is not glossy and has a poor appearance.

The compounding compositions and results are shown in Tables 1 to 3 below.

Claims (6)

The composition comprises a vinyl chloride resin (excluding vinyl chloride resins obtained by graft-copolymerizing an acrylic copolymer with vinyl chloride), an acrylic resin having a weight-average molecular weight of 100,000 or more and 500,000 or less, and calcium carbonate,
the content of the acrylic resin is 0.5 parts by weight or more and 6 parts by weight or less, and the content of the calcium carbonate is 0.5 parts by weight or more and 5 parts by weight or less, relative to 100 parts by weight of the vinyl chloride resin;
a vinyl chloride resin composition comprising the secondary particles of calcium carbonate,
The average particle size of the primary particles of the calcium carbonate is 0.5 μm or more,
The average particle size of the secondary particles of the calcium carbonate is 15 μm or less. 2. The vinyl chloride resin composition according to claim 1, wherein the content of the calcium carbonate is 0.5 parts by weight or more and 3 parts by weight or less based on 100 parts by weight of the vinyl chloride resin. 3. The vinyl chloride resin composition according to claim 1, which does not contain a polyethylene-based lubricant or contains a polyethylene-based lubricant in an amount of 2 parts by weight or less per 100 parts by weight of the vinyl chloride resin. Contains polyethylene lubricant,
The vinyl chloride resin composition according to any one of claims 1 to 3 , wherein the polyethylene lubricant has an acid value of 10 or more and 30 or less. The vinyl chloride resin composition according to any one of claims 1 to 4 , which is a vinyl chloride resin composition for injection molding. A joint obtained by molding the vinyl chloride resin composition according to any one of claims 1 to 5 .