Vinyl chloride resin composition, electric wire, and cable

Abstract

To provide a vinyl chloride resin composition that exhibits enhanced oil resistance and enhanced kneading characteristics during mixing, an electric wire produced using the vinyl chloride resin composition, and a cable produced using the vinyl chloride resin composition.SOLUTION: A vinyl chloride resin composition comprises a vinyl chloride resin, a trimellitate ester plasticizer, a polyester-based plasticizer, calcium carbonate particles surface-treated with a surface treatment agent, a zinc stannate compound, and an acrylic polymer, wherein the acrylic polymer includes a first acrylic polymer and a second acrylic polymer, the weight-average molecular weight of the first acrylic polymer being greater than the weight-average molecular weight of the second acrylic polymer, and the content of the acrylic polymer being more than 12.5 pts.mass and less than 20 pts.mass relative to 100 pts.mass of the vinyl chloride resin.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vinyl chloride resin composition, an electric wire, and a cable. [Background technology]

[0002] Depending on the degree of polymerization of vinyl chloride monomer (chloroethylene) and the type and amount of plasticizer added, vinyl chloride resin products can be used to manufacture products with a wide range of physical properties, from rigid vinyl chloride resin to flexible vinyl chloride resin. Furthermore, because vinyl chloride resin is inexpensive and can be produced in large quantities, it is used as an industrial resin material in a wide range of industries, including components and building materials for electric wires and cables. Because vinyl chloride resin has high flame retardancy and excellent electrical insulation, chemical resistance, water resistance, and colorability, it has traditionally been used as the base for resin compositions used to make insulators and sheaths (the outer layer of cables) in electric wires and cables.

[0003] However, vinyl chloride resin contains a large amount of chlorine in its structure, and therefore generates harmful hydrogen chloride gas when burned. In recent years, in consideration of the environment, specified values ​​have been established to minimize the amount of hydrogen chloride gas generated during combustion, depending on the application. One possible means of suppressing the amount of hydrogen chloride gas generated when vinyl chloride resin is burned is to add a large amount of fine inorganic filler to vinyl chloride resin.

[0004] For example, Patent Document 1 (JP 2015-225837 A) discloses an insulated wire having a conductor and an insulator covering the outer periphery of the conductor, the insulator containing a chlorinated polyvinyl chloride resin and a polyvinyl chloride thermoplastic elastomer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-225837 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when fine inorganic fillers are added to a resin composition, if the system does not have sufficient viscosity, the inorganic fillers may not be uniformly dispersed. As a result, the hydrogen chloride gas generated from the vinyl chloride resin may not be sufficiently captured. Furthermore, the addition of inorganic fillers may reduce the oil resistance of the insulation material for electric wires and cables. As a result, the insulation material may not meet the required specifications.

[0007] The present invention has been made in view of the above, and an object of the present invention is to provide a vinyl chloride resin composition having improved oil resistance and improved kneadability during kneading, an electric wire using the vinyl chloride resin composition, and a cable using the vinyl chloride resin composition. [Means for solving the problem]

[0008] A vinyl chloride resin composition according to one embodiment of the present invention comprises a vinyl chloride resin, a trimellitate ester plasticizer, a polyester plasticizer, calcium carbonate particles surface-treated with a surface treatment agent, a zinc stannate compound, and an acrylic polymer, wherein the acrylic polymer comprises a first acrylic polymer and a second acrylic polymer, the weight-average molecular weight of the first acrylic polymer being greater than the weight-average molecular weight of the second acrylic polymer, and the content of the acrylic polymer is greater than 12.5 parts by mass and less than 20 parts by mass per 100 parts by mass of the vinyl chloride resin.

[0009] An electric wire according to one embodiment of the present invention includes a conductor and an insulating layer covering the conductor, the insulating layer containing a vinyl chloride resin composition, the vinyl chloride resin composition containing a vinyl chloride resin, a trimellitate ester plasticizer, a polyester-based plasticizer, calcium carbonate particles surface-treated with a surface treatment agent, a zinc stannate compound, and an acrylic polymer, the content of the acrylic polymer being more than 12.5 parts by mass and less than 20 parts by mass per 100 parts by mass of the vinyl chloride resin.

[0010] A cable according to one embodiment of the present invention includes a conductor, an insulating layer covering the conductor, and a covering layer covering the insulating layer, wherein the covering layer contains a vinyl chloride resin composition, and the vinyl chloride resin composition contains vinyl chloride resin, a trimellitate ester plasticizer, a polyester-based plasticizer, calcium carbonate particles surface-treated with a surface treatment agent, a zinc stannate compound, and an acrylic polymer, and the content of the acrylic polymer is more than 12.5 parts by mass and less than 20 parts by mass per 100 parts by mass of the vinyl chloride resin. [Effects of the Invention]

[0011] One aspect of the present invention can provide a vinyl chloride resin composition having improved oil resistance and improved kneadability during kneading, an electric wire using the vinyl chloride resin composition, and a cable using the vinyl chloride resin composition. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram of the wire manufacturing (extrusion) process. [Figure 2] FIG. 2 is a cross-sectional schematic diagram of an electric wire and a cable. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments will be described in detail with reference to the drawings. In the following embodiments, as a general rule, descriptions of identical or similar parts will not be repeated unless particularly necessary.

[0014] <<Vinyl chloride resin composition>> A vinyl chloride resin composition according to one embodiment of the present invention will be described. The vinyl chloride resin composition according to one embodiment of the present invention contains a vinyl chloride resin, a trimellitate ester plasticizer, a polyester-based plasticizer, calcium carbonate particles, a zinc stannate compound, and an acrylic polymer. The vinyl chloride resin composition according to one embodiment of the present invention may be a PVC (polyvinyl chloride) composition.

[0015] The kneading property, tensile properties, and oil resistance of the vinyl chloride resin composition of this embodiment can be measured using the kneading property test, tensile test, and oil resistance test specified in JIS K 6723. The vinyl chloride resin composition of this embodiment may be used for covering electric wires or cables.

[0016] <Vinyl chloride resin> The physical properties of vinyl chloride resin products can be controlled over a wide range, from hard to soft, by adjusting the degree of polymerization of the monomer vinyl chloride (chloroethylene) and the type and amount of plasticizer added. The vinyl chloride resin composition of this embodiment preferably uses a vinyl chloride resin as its base. The degree of polymerization of the vinyl chloride resin is preferably 2000 or more and 3000 or less, and more preferably approximately 2500. This allows the vinyl chloride resin composition to have an appropriate material viscosity. Furthermore, the kneading processability and oil resistance of the vinyl chloride resin composition can be further improved. Known vinyl chloride resin compositions can be used.

[0017] <Acrylic polymer> The acrylic polymer of this embodiment includes a first acrylic polymer and a second acrylic polymer. The weight-average molecular weight of the first acrylic polymer is greater than the weight-average molecular weight of the second acrylic polymer. The content of the acrylic polymer is greater than 12.5 parts by mass and less than 20 parts by mass per 100 parts by mass of the vinyl chloride resin. This can further improve oil resistance and adhesion during kneading.

[0018] An acrylic polymer may be added as a processing aid. This allows the powdered vinyl chloride resin to be quickly kneaded (gelled; hereinafter, simply referred to as "gelling") in a kneader. Furthermore, by increasing the shear stress (kneading torque) applied to the PVC material during kneading, the dispersibility of the filler can be improved, resulting in improved oil resistance.

[0019] The content of the acrylic polymer is more preferably more than 12.5 parts by mass and less than 20 parts by mass relative to 100 parts by mass of the vinyl chloride resin. Known acrylic polymers can be used.

[0020] Adding the first acrylic polymer as a processing aid (thickener) to the resin composition increases the torque during kneading, thereby increasing the viscosity of the entire system, improving the dispersibility of the inorganic filler, and improving oil resistance.

[0021] To ensure satisfactory kneadability of the resin composition, it is preferable to add an appropriate amount of the first acrylic polymer. If the amount of the first acrylic polymer added is small, the viscosity of the entire system will be low, resulting in poor kneading during kneading, which can lead to problems such as non-uniform dispersion of the inorganic filler and the potential for improved oil resistance. On the other hand, if the amount of the first acrylic polymer added is excessive, the viscosity will increase, placing a heavy load on the kneading device, making kneading difficult and potentially resulting in insufficient kneadability. Furthermore, self-heating of the material may occur during kneading, potentially resulting in thermal degradation of the vinyl chloride resin or hydrogen chloride desorption. Therefore, the content of the first acrylic polymer is preferably more than 2.5 parts by mass and less than 10 parts by mass per 100 parts by mass of vinyl chloride resin.

[0022] Conventionally, powdered vinyl chloride resin is introduced into a kneader together with various additives, where it is subjected to shear stress to gel, after which the additives must be distributed into the vinyl chloride resin and further subjected to shear stress to homogeneously disperse the additives.

[0023] Adding the first acrylic polymer as a processing aid increases the shear stress (kneading torque) applied to the PVC material during kneading, thereby improving the dispersibility of the filler. If the amount of the first acrylic polymer added is insufficient, the adhesion may be insufficient. Furthermore, if the amount of the first acrylic polymer added is excessive, there is a concern that the adhesion of the vinyl chloride resin composition may increase, the adhesion may not be satisfactory, and the processability of the vinyl chloride resin composition may be adversely affected. Therefore, the weight-average molecular weight of the first acrylic polymer used as the processing aid in this embodiment is preferably 1,000,000 or more, more preferably 1,200,000 or more and 5,000,000 or less, and even more preferably 2,700,000 or more and 3,500,000 or less.

[0024] Furthermore, the addition of the second acrylic polymer can shorten the time from when the powdered vinyl chloride resin and various additives are introduced into the kneader until gelation. This shortens the overall kneading time and allows the kneading time required to disperse the various additives within the set kneading time to be extended. The weight-average molecular weight of the second acrylic polymer used as the processing aid in this embodiment is preferably less than 1,000,000, more preferably from 200,000 to 900,000, and even more preferably from 200,000 to 300,000.

[0025] <Trimellitic acid ester plasticizer> In this embodiment, a trimellitic acid ester is used as a plasticizer. This makes it possible to avoid the use of phthalic acid esters, which are of concern for their environmental impact. As a result, the vinyl chloride resin composition can be easily used as a wire coating material. The trimellitic acid ester in this embodiment is not particularly limited and may be one or a mixture of two or more of trimellitic acid tris-2-ethylhexyl ester, trimellitic acid isononyl ester, and trimellitic acid mixed linear alkyl ester. From the viewpoints of high plasticization efficiency and excellent economic efficiency, it is preferable to use trimellitic acid tris-2-ethylhexyl ester as a plasticizer. The content of the trimellitic acid ester is preferably 30 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the vinyl chloride resin.

[0026] <Polyester-based plasticizer> There are a wide variety of polyester plasticizers with viscosities of 100 MPa·s or more and 10,000 MPa·s or less at 25°C. When used as a plasticizer, there are no particular limitations on the viscosity. In view of the requirements for wire coating materials that suppress the amount of hydrogen chloride gas generated during combustion, high oil resistance, and high electrical insulation, in this embodiment, the plasticizer used preferably has a viscosity of 1,000 MPa·s or more and 5,000 MPa·s or less at 25°C, and more preferably has a viscosity of about 3,000 MPa·s.

[0027] The polyester plasticizer in this embodiment is not particularly limited, and examples thereof include adipic acid polyesters, sebacic acid polyesters, and aromatic polyesters. From the viewpoint of versatility and economy, adipic acid polyesters are more preferred. The content of the polyester plasticizer is preferably 5 parts by mass or more and 80 parts by mass or less per 100 parts by mass of the vinyl chloride resin.

[0028] <Surface-treated calcium carbonate particles> Adding calcium carbonate to vinyl chloride resin can capture hydrogen chloride gas generated during combustion of vinyl chloride resin. Therefore, calcium carbonate may be added to vinyl chloride resin as a hydrogen chloride gas absorbent. In particular, calcium carbonate particles with a particle size of 1.0 μm or less can capture hydrogen chloride gas generated during combustion more efficiently. The calcium carbonate particles in this embodiment preferably have a particle size of 0.2 μm or more and 1.0 μm or less. However, as the particles become smaller, the specific surface area increases, making them more likely to aggregate. Aggregated calcium carbonate particles reduce the capture efficiency of hydrogen chloride gas generated during combustion and reduce the oil resistance of vinyl chloride resin compositions containing the aggregated calcium carbonate particles. Therefore, the calcium carbonate particles used in this embodiment are surface-treated with a surface treatment agent to prevent aggregation.

[0029] As the surface treatment agent for calcium carbonate particles of this embodiment, fatty acids, fatty acid esters obtained by reacting fatty acids with alcohols, and surface treatment agents other than fatty acids can be used as long as they can suppress aggregation of calcium carbonate particles. Fatty acids in this embodiment include medium-chain saturated fatty acids having 6 to 12 carbon atoms, medium-chain unsaturated fatty acids having 6 to 12 carbon atoms, long-chain saturated fatty acids having 13 or more carbon atoms, and long-chain unsaturated fatty acids having 13 or more carbon atoms. Fatty acids are not limited to these. Examples of fatty acids include stearic acid, lauric acid, palmitic acid, myristic acid, caprylic acid, capric acid, oleic acid, linoleic acid, linolenic acid, arabinan ... Examples of the surface treatment agent include chidonic acid, eicosapentaenoic acid, and docosahexaenoic acid. The fatty acid is not limited to these. Examples of the surface treatment agent other than fatty acids include silane coupling agents.

[0030] The content of calcium carbonate particles is preferably 30 parts by mass or more and 80 parts by mass or less relative to 100 parts by mass of vinyl chloride resin.

[0031] <Zinc stannate compound> When an appropriate amount of zinc stannate compound is added to vinyl chloride resin, a char is formed during combustion, covering at least a portion of the surface of the material. This suppresses combustion and prevents the emission of hydrogen chloride gas generated during combustion. However, adding a large amount of zinc stannate compound to vinyl chloride resin reduces the dispersibility of the zinc stannate compound, thereby reducing the oil resistance of the vinyl chloride resin composition. From the viewpoint of balancing flame retardancy and oil resistance, the content of the zinc stannate compound is preferably 5 to 15 parts by mass per 100 parts by mass of vinyl chloride resin.

[0032] Furthermore, from the viewpoint of use as a wire coating material, when a zinc stannate compound containing many hydroxyl groups, such as zinc hydroxystannate, is used, it is preferable to add it in combination with zinc borate to prevent a decrease in the electrical insulation properties of the vinyl chloride resin composition.

[0033] <Other additives> The vinyl chloride resin composition used as a wire covering material may contain antioxidants, insulating property improvers, flame retardants, etc. in order to satisfy required properties such as certain mechanical strength and insulating properties.

[0034] (antioxidant) The antioxidant in this embodiment is preferably a phenol-based antioxidant, such as pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (CAS No. 6683-19-8), 2,2'-thiodiethylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (CAS No. 41484-35-9), n-octadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate (CAS No. 2082-79-3), octyl-3,5-ditert-butyl-4-hydroxyphenyl)propionate (CAS No. 2082-79-3), or octyl-3,5-ditert-butyl-4-hydroxyphenylpropionate (CAS No. 2082-79-3). t-Butyl-4-hydroxy-hydrocinnamate (CAS No. 125643-61-0), 2,4-bis[(dodecylthio)methyl]-6-methylphenol (CAS No. 110675-26-8), benzenepropanoic acid, 3-(1,1-dimethylethyl)-4-hydroxy-5-methyl-, 1,2-ethanediylbis(oxy-2,1-ethanediyl) ester (CAS No. 36443-68-2), 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4 ,6(1H,3H,5H)-trione isocyanuric acid tris(3,5-di-tert-butyl-4-hydroxybenzyl) (CAS No. 27676-62-6), 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane (CAS No. 1843-03-4), 4,4'-butylidenebis(6-tert-butyl-m-cresol) (CAS No. 85-60-9), 2,2'-dimethyl-2,2'-(2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diyl )dipropane-1,1'-diyl bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propanoate] (CAS No. 90498-90-1), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene (CAS No. 1709-70-2), 4,4',4'',4'''-methanetetrayltetraphenoltetrakis(4-hydroxyphenyl)methane 4-[tris(4-hydroxyphenyl)methyl]phenol (CAS No.53184-78-4), N,N'-(1,3-propanediyl)bis[3,5-di-tert-butyl-4-hydroxybenzenepropanamide] (CAS No. 69851-61-2), N,N'-(hexane-1,6-diyl)bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide] (CAS No. 23128-74-7), 2-methyl-4,6-bis[(n-octylthio)methyl]phenol (CAS No. 110553-27-0), tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate (CAS No. 40601-76-1), 3-(1,1-dimethylethyl)benzenepropanoate Examples of suitable antioxidants include 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-N'-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoyl]propanehydrazide (CAS No. 32687-78-8), and bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoic acid][oxalylbis(azanediyl)]bis(ethane-2,1-diyl) (CAS No. 70331-94-1). The phenolic acid antioxidants may be used alone or in combination.

[0035] To achieve a more excellent antioxidant function, it is more preferable to use it in combination with a sulfur-containing compound such as pentaerythritol tetrakis[3-laurylthiopropionate] (CAS No. 29598-76-3) or ditridecyl 3,3'-thiobispropionate (CAS No. 10595-72-9).

[0036] Furthermore, the phenol-based antioxidant can be used in combination with an amine-based antioxidant. Examples of the amine-based antioxidant include poly(2,2,4-trimethyl-1,2-dihydroquinoline) (CAS No. 26780-96-1), 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline (CAS No. 91-53-2), reaction product of diphenylamine and acetone (CAS No. 68412-48-6), 1-N-(4-methylpentan-2-yl)-4-N-phenylbenzene-1,4-diamine (CAS No. 793-24-8), and N-isopropyl-N'-phenyl-p-phenylenediamine. Examples of suitable antioxidants include N,N'-di-2-naphthyl-1,4-phenylenediamine (CAS No. 93-46-9), p-(p-toluenesulfonylamido)diphenylamine (CAS No. 100-93-6), 4,4'-bis(α,α-dimethylbenzyl)diphenylamine (CAS No. 10081-67-1), 4,4'-dioctyldiphenylamine (CAS No. 101-67-7), and N-phenyl-1-naphthylamine (CAS No. 90-30-2).Pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (CAS No. 6683-19-8) is more preferably used as the phenolic antioxidant. The method for adding the phenolic acid antioxidant or a mixture thereof is not particularly limited, and examples thereof include a master batch in which the phenolic acid antioxidant is mixed with a resin.

[0037] (Insulation improver) The insulating property improver in this embodiment may be a clay-containing compound. Examples of the insulating property improver include the LHM series of Insulite (registered trademark) manufactured by Mizusawa Chemical Industries, Ltd.

[0038] (Flame retardant) In this embodiment, the flame retardant is preferably an antimony oxide compound that exhibits a synergistic effect with the halogen elements contained in the vinyl chloride resin. Specific examples include antimony trioxide and antimony pentoxide, with antimony trioxide being more preferred. In addition to the above, other additive components can be blended into the vinyl chloride resin composition as needed. Examples of such additive components include lubricants, surfactants, inorganic and organic fillers, reinforcing agents, bulking agents, crosslinking agents, silicon coupling agents, compatibilizers, copper degradation inhibitors, UV absorbers, light stabilizers, and colorants.

[0039] (Preparation of vinyl chloride resin composition) The vinyl chloride resin composition can be prepared by mixing and melt-kneading the above-described components using a known kneading device, such as a batch kneader such as a Banbury mixer or a pressure kneader, or a continuous kneader such as a twin-screw extruder.

[0040] The vinyl chloride resin composition obtained as described above can be a vinyl chloride resin composition that satisfies the oil resistance specified by JIS K 6723 and has been imparted with kneadability. By preparing such a resin composition, it is possible to provide a wire coating material that satisfies the oil resistance specified by JIS and has excellent kneadability.

[0041] <<Wire>> The electric wire in this embodiment has an insulating layer made of the vinyl chloride resin composition. An example of this electric wire is an electric wire 9 in which the outer periphery of a conductor 8 is covered with an insulating layer 11, as shown in Fig. 2. In this case, the insulating layer 11 is made of the vinyl chloride resin composition described above.

[0042] Here, the conductor 8 may be any commonly used metal wire. For example, copper wire, copper alloy wire, aluminum wire, gold wire, silver wire, etc. may be used as the conductor 8. Alternatively, the conductor 8 may be a metal wire plated with metal such as tin or nickel. Furthermore, a twisted conductor made by twisting metal wires may also be used as the conductor 8.

[0043] Fig. 1 is a diagram showing a schematic configuration of an example of an extruder for producing an electric wire according to the present embodiment. As shown in Fig. 1, the extruder 1 includes a cylinder 10, a screw 3 rotatably provided within the cylinder 10, a hopper 2 for supplying material into the cylinder 10, and a crosshead 6. The extruder 1 also includes a neck 5 between the crosshead 6 and the screw 3, and a breaker plate 4 between the neck 5 and the screw 3. The crosshead 6 has a die 7. A conductor 8 passing through the crosshead 6 is coated with an insulating layer within the crosshead 6, passes through the die 7, and is drawn out from the crosshead 6 as an electric wire 9.

[0044] <<Cable>> 2 may be bundled together to form a cable 13. As an example of this cable 13, as shown in FIG. 2, a cable 13 in which the outer periphery of a conductor 8 is covered with an insulating layer 11 and the outer periphery of the wire is further covered with a covering layer (sheath) 12 can be exemplified.

[0045] 2, the insulating layer 11 may be made of an insulating material typically used for insulating wires. Examples of insulating materials for the insulating layer 11 include polyvinyl chloride, fluororesin, cross-linked polyethylene, natural rubber, synthetic rubber, etc. Alternatively, the insulating layer 11 may be made of the vinyl chloride resin composition described above.

[0046] The covering layer (sheath) 12 is made of the vinyl chloride resin composition described above. In this case, when bundling multiple electric wires, the wires are bundled together with the inserts, and a pressure winding tape is applied to the outer periphery to form the covering layer (sheath) 12 as the outermost layer.

[0047] A method for manufacturing cable 13 may be mentioned in which, in the same manner as in the above-mentioned method for manufacturing an electric wire, conductor 8 is replaced with electric wire 9, and an extruder is used to form a coating layer (sheath) by covering the outer periphery of electric wire 9 with the vinyl chloride resin composition described above. [Example]

[0048] The following embodiments are examples of wire and cable production using the vinyl chloride resin composition of the present invention as an electric wire insulator or a cable sheath, for the purpose of understanding the present invention. There are no limitations on the type of conductor, structure, interposition, semiconductive layer, hold-down tape, shielding braid, or reinforcing layer of the electric wire or cable structure or application.

[0049] The following describes one embodiment of kneading vinyl chloride resin with various additives, preparing a sheet for evaluating the properties of the vinyl chloride resin composition, and preparing an electric wire using the vinyl chloride resin composition, but the present invention is not limited thereto. The electric wire to be prepared is also one example, and a cable shape may be obtained by applying extrusion coating to an electric wire (a conductor coated with an insulator). There are no limitations on the extrusion conditions, conductor and insulator materials, or electric wire / cable structure.

[0050] The internal mixer kneader used in the following examples will be given as an example. Other kneading devices are not particularly limited as long as they are commonly used, such as a roll mill, extruder, kneader, autoclave, etc. Furthermore, there are no limitations on the kneading conditions.

[0051] <Mixing vinyl chloride resin with various additives> The vinyl chloride resin and various additives were weighed out in the amounts shown in Table 2, and the total weight was adjusted to 249.8 g to 259.8 g. The mixture was added to a stainless steel container, heated at 90°C for 4 hours, and then left at room temperature overnight. The vinyl chloride resin and various additives were stirred in the stainless steel container and then placed in a 2000 mL internal mixer / kneader equipped with a closed-type two-blade rotor (hereinafter also referred to as a closed-type mixer / kneader) that had been preheated to 170°C. After all the materials were in the container, the pressure lid was removed, the rotor speed was set to 30 rpm, and mixing began. Five minutes after the start of mixing, the rotor rotation was stopped, the pressure lid was lifted, and the mixed materials were removed from the container.

[0052] <Preparation of characteristic evaluation sheet> The roll surface temperature of a 6-inch roller was set to 170°C, and the gap between the rolls was set to 1 mm. The kneaded material was quickly formed into a sheet using the 6-inch roller under the above conditions to minimize shear stress, and then heated and pressed at 180°C for 5 minutes using a press molding machine to obtain a 1 mm thick sheet for property evaluation. Table 2 shows Examples 1-2 and Comparative Examples 1-3.

[0053] <Making electric wires> The obtained sheet for property evaluation was processed using the 6-inch roller to obtain 4 mm square pellets. The 4 mm square pellets were fed into a single-screw extruder, and a vinyl chloride resin composition was extruded onto the conductor under the conditions shown in Table 1 to produce an electric wire. In this example, a 1.25 SQ conductor made of multiple twisted tin-plated annealed copper wires was used, and a 0.78 mm thick vinyl chloride resin composition was extruded as an insulator to coat the conductor.

[0054] [Table 1]

[0055] <<Evaluation>> The vinyl chloride resin compositions and vinyl chloride resin sheets obtained in each example were evaluated for the following properties. The results are shown in Table 2.

[0056] <Test for adhesion during mixing> The maximum torque was considered to be the point at which the vinyl chloride resin was kneaded in the kneader, and was used as an index of kneadability. Using Comparative Example 1 as a base, the increase rate of maximum torque for each Comparative Example and Example in which an acrylic polymer was added was calculated using the following calculation formula 1. An increase rate of less than 25% was deemed to have sufficiently improved kneadability and was considered to have passed (Table 2), while an increase rate of 25% or more was deemed to have been difficult to knead and was considered to have failed. (Formula 1) Increase rate (%) relative to Comparative Example 1 = {(B A) / A} × 100 A: Maximum torque (N m) for Comparative Example 1 (first acrylic polymer not added) B: Maximum torque (N m) for the comparative example and the working example

[0057] <Tensile test (evaluation of tensile properties)> The sheet for property evaluation was cut into the shape of a No. 2 dumbbell test piece as specified in JIS K6723, and was stretched at a speed of 200 mm / min using a Tensilon type small tensile tester STA-1225 (manufactured by Orientec Co., Ltd.) to measure the elongation at break. The test was performed three times (n=3), and the average value of the three measurements was calculated.

[0058] The sheet for property evaluation with an elongation of 150% or more was judged as passing (marked with a circle in Table 2), and the sheet for property evaluation with an elongation of less than 150% was judged as failing (marked with an x ​​in Table 2).

[0059] <Oil resistance test> A characteristic evaluation sheet shaped like a Type 2 dumbbell test specimen as specified in JIS K6723 was immersed for 4 hours in test oil (IRM902 oil: manufactured by Nippon San Oil) heated to 85°C. The test oil adhering to the surface was then wiped off, and the specimen was left at room temperature for 24 hours. The specimen was then stretched under the same conditions as the tensile test (speed of 200 mm / min), and the tensile load at break and the elongation retention of the dumbbell test specimen were calculated using the above-mentioned formula 2. The test was performed three times (n=3), and the average of the three values ​​was calculated. The elongation retention was calculated using the following formula 2, using the elongation before and after immersion in the test oil. (Formula 2) Elongation retention rate (%) = (elongation after immersion in test oil (%) / elongation before immersion in test oil (%)) × 100%

[0060] The sheet for property evaluation with a residual elongation rate of 70% or more was judged as passing (marked with a circle in Table 2), and the sheet for property evaluation with a residual elongation rate of less than 70% was judged as failing (marked with an x ​​in Table 2).

[0061] [Table 2] *1TH-2500 (for soft materials), manufactured by Taiyo PVC *2 Trimex T-08A, manufactured by Kao Corporation *3 Adeka Cizer PN1030 (viscosity 3000 MPa·s (25°C)), manufactured by ADEKA Corporation *4 Manufacturer-developed products *5 Songnox1010, manufactured by SONGWON *6Metabrene P-570A, manufactured by Mitsubishi Chemical Corporation *7Metablen P-530A, manufactured by Mitsubishi Chemical Corporation *8 Insulite LHM-103HP, manufactured by Mizusawa Chemicals *9 Antimony trioxide, manufactured by TwinklingStar *10 Alkanex ZS, manufactured by Mizusawa Chemicals *11 Lighton 32X, manufactured by Bihoku Nuka Kogyo Co., Ltd.

[0062] The resin compositions in each example were prepared as shown in Table 2 as follows.

[0063] (Example 1-2) 100 parts by mass of polyvinyl chloride resin (*1 Taiyo PVC, TH-2500 (for soft use)), 50 parts by mass of trioctyl trimellitate (*2 Kao, Trimex T-08A), 10 parts by mass of polyester plasticizer (*3 ADEKA, viscosity 3000 MPa·s at 25°C, Adeka Cizer PN1030), 4 parts by mass of Ca-Zn composite stabilizer (*4 fatty acid calcium and fatty acid zinc mixture), 0.5 parts by mass of phenolic compound (*5 SONGWON, Songnox 1010), acrylic polymer (*6 Mitsubishi Chemical, Metablen P-570 A resin composition was obtained by kneading 10 parts by mass of A), 5 and 7.5 parts by mass of an acrylic polymer (*7 Mitsubishi Chemical Corporation, Metablen P-530A), 0.5 parts by mass of a clay-containing compound serving as an insulation improver (*8 Mizusawa Chemical Industries, Ltd., Insulite (registered trademark) LHM-103HP), 9.8 parts by mass of antimony trioxide (*9 TwinklingStar Corporation), 15 parts by mass of zinc stannate (*10 Mizusawa Chemical Industries, Ltd., Alkanex (registered trademark) ZS), and 50 parts by mass of calcium carbonate (*11 Bihoku Powder Industry Co., Ltd., Ryton 32X, average particle size 0.7 μm, surface treatment agent: fatty acid).

[0064] (Comparative Examples 1-3) 100 parts by mass of polyvinyl chloride resin (*1 Taiyo PVC, TH-2500 (soft use)), 50 parts by mass of trioctyl trimellitate (*2 Kao, Trimex T-08A), 10 parts by mass of polyester plasticizer (*3 ADEKA, viscosity 3000 MPa·s at 25°C, Adeka Cizer PN1030), 4 parts by mass of Ca-Zn composite stabilizer (*4 fatty acid calcium and fatty acid zinc mixture), 0.5 parts by mass of phenolic compound (*5 SONGWON, Songnox 1010), acrylic polymer (*6 Mitsubishi Chemical, Metablen P-570A) A resin composition was obtained by kneading 10 parts by mass of the above, 0, 2.5, and 10 parts by mass of an acrylic polymer (*7 Mitsubishi Chemical Corporation, Metablen P-530A), 0.5 parts by mass of a clay-containing compound serving as an insulation improver (*8 Mizusawa Chemical Industries, Ltd., Insulite (registered trademark) LHM-103HP), 9.8 parts by mass of antimony trioxide (*9 TwinklingStar Corporation), 15 parts by mass of zinc stannate (*10 Mizusawa Chemical Industries, Ltd., Alkanex (registered trademark) ZS), and 50 parts by mass of calcium carbonate (*11 Bihoku Powder Industry Co., Ltd., Ryton 32X, average particle size 0.7 μm, surface treatment agent: fatty acid).

[0065] According to the method described in the "Evaluation" section above, the evaluation items are a test of kneadability when kneaded using an internal mixer kneader, a tensile test (evaluation of tensile properties), and an oil resistance test. If the test passes all the items comprehensively, it is judged as passing, and if it fails even one item, it is judged as failing.

[0066] The vinyl chloride resin composition prepared according to the formulation shown in Example 1-2 was evaluated for its adhesiveness during kneading in an internal mixer kneader, and various properties were evaluated using an evaluation sheet prepared from the vinyl chloride resin composition. All of the targets were met.

[0067] As shown in Table 2, Comparative Example 1, in which the first acrylic polymer was not added as a processing aid, failed in oil resistance (elongation retention). This result suggests that the various additives were not sufficiently dispersed in the vinyl chloride resin due to insufficient viscosity of the first acrylic polymer, which reduced the oil resistance of the vinyl chloride resin composition.

[0068] It was found that Comparative Example 2, in which 2.5 parts by mass of the first acrylic polymer was added as a processing aid to 100 parts by mass of the vinyl chloride resin composition, had almost the same oil resistance as Comparative Example 1, but did not meet the target oil resistance (elongation retention). This is thought to be because the addition of the first acrylic polymer tends to improve oil resistance (elongation retention).

[0069] On the other hand, in Comparative Example 3, in which 10 parts by mass of the first acrylic polymer was added, the viscosity of the material was too high, which caused difficulty in kneading due to the high load on the device, and it is thought that this did not satisfy the torque peak increase rate.

[0070] The present invention is not limited in any way to the vinyl chloride resins and additives used in the above examples. Furthermore, the wire configuration, consisting of a conductor and a covering material (insulator) as prepared in this example, is not limited. It is also possible to use a cable in which the vinyl chloride resin composition of the present invention is coated as a sheath (outer layer) around the outer periphery of the insulator. In this case, the material for the inner layer of the insulator may be the vinyl chloride resin composition of the present invention or another resin composition or rubber composition.

[0071] The present invention has been described using the above-mentioned embodiments and examples, but the present invention is not limited to the above-mentioned embodiments and examples and can be modified in various ways without departing from the spirit of the invention.

[0072] (Explanation of the description format, basic terms and usage in this application) In this application, the description of the embodiments will be divided into multiple sections, etc., for convenience, as necessary. However, unless otherwise expressly stated, these are not mutually independent and separate, and regardless of the order of description, they are each part of a single example, one being a partial detail of the other, or a partial or complete modification, etc. Furthermore, as a general rule, repeated explanations of similar parts will be omitted. Furthermore, each component in the embodiments is not essential unless otherwise expressly stated, there is a theoretical limit to the number, or it is clearly not essential from the context. When a specific number or quantity is mentioned, unless otherwise specified, unless it is theoretically limited to that number, or unless the context clearly indicates otherwise, the number may be greater than or less than that specific number. Furthermore, in each drawing of the embodiment, the same or similar parts are indicated by the same or similar symbols or reference numbers, and descriptions thereof will not be repeated in principle. In the accompanying drawings, hatching may be omitted even in cross sections if it would be too complicated or if the distinction from voids is clear. In relation to this, background contour lines may be omitted even in the case of holes that are closed in plan view if it is clear from the description, etc. Furthermore, hatching or dot patterns may be added even in cases where the drawing is not a cross section to clearly indicate that the hole is not a void or to clearly indicate the boundary of the area. [Industrial Applicability]

[0073] INDUSTRIAL APPLICABILITY The present invention can provide a vinyl chloride resin composition having improved oil resistance and improved kneadability during kneading, an electric wire using the vinyl chloride resin composition, and a cable using the vinyl chloride resin composition, and therefore has high industrial applicability. [Explanation of symbols]

[0074] 1. Extruder 2 Hopper 3 screws 4 Breaker Plate 5 Neck 6 Crosshead 7 Dice 8 Conductors 9 Electric wire 10 cylinders 11 Insulating layer 12 Covering layer 13 Cable

Claims

1. The composition comprises a vinyl chloride resin, a trimellitic ester plasticizer, a polyester-based plasticizer, calcium carbonate particles that have been surface-treated with a surface treatment agent, a zinc stannate compound, and an acrylic polymer; the acrylic polymer includes a first acrylic polymer and a second acrylic polymer; the weight average molecular weight of the first acrylic polymer is greater than the weight average molecular weight of the second acrylic polymer; The vinyl chloride resin composition, wherein the content of the acrylic polymer is more than 12.5 parts by mass and less than 20 parts by mass per 100 parts by mass of the vinyl chloride resin.

2. The vinyl chloride resin composition according to claim 1, A vinyl chloride resin composition, wherein the first acrylic polymer has a weight average molecular weight of 1,000,000 or more, and the second acrylic polymer has a weight average molecular weight of less than 1,000,000.

3. The vinyl chloride resin composition according to claim 2, a weight average molecular weight of the first acrylic polymer of 1,200,000 or more and 5,000,000 or less, and a weight average molecular weight of the second acrylic polymer of 200,000 or more and 900,000 or less;

4. The vinyl chloride resin composition according to claim 1, a content of the first acrylic polymer in the vinyl chloride resin composition is more than 2.5 parts by mass and less than 10 parts by mass per 100 parts by mass of the vinyl chloride resin;

5. The vinyl chloride resin composition according to claim 1, The vinyl chloride resin composition, wherein the trimellitic acid ester plasticizer is trimellitic acid tris-2-ethylhexyl ester.

6. The vinyl chloride resin composition according to claim 1, The vinyl chloride resin composition, wherein the polyester plasticizer is an adipic acid polyester.

7. The vinyl chloride resin composition according to claim 1, The vinyl chloride resin composition, wherein the degree of polymerization of the vinyl chloride resin is 2000 or more and 3000 or less.

8. The vinyl chloride resin composition according to claim 1, Further, the composition contains an antioxidant, an insulation improver, and a flame retardant, A vinyl chloride resin composition, wherein the antioxidant is a phenolic compound, the insulation improver is a clay-containing compound, and the flame retardant is an antimony oxide compound.

9. The vinyl chloride resin composition according to claim 1, A vinyl chloride resin composition for use in covering electric wires or cables.

10. A conductor and an insulating layer coated around the conductor, the insulating layer contains a vinyl chloride resin composition, The vinyl chloride resin composition includes a vinyl chloride resin, a trimellitate ester plasticizer, a polyester-based plasticizer, calcium carbonate particles surface-treated with a surface treatment agent, a zinc stannate compound, and an acrylic polymer; The electric wire, wherein the content of the acrylic polymer is more than 12.5 parts by mass and less than 20 parts by mass relative to 100 parts by mass of the vinyl chloride resin.

11. The insulating layer is coated around a conductor, and the insulating layer is coated around the conductor. the coating layer contains a vinyl chloride resin composition, The vinyl chloride resin composition includes a vinyl chloride resin, a trimellitate ester plasticizer, a polyester-based plasticizer, calcium carbonate particles surface-treated with a surface treatment agent, a zinc stannate compound, and an acrylic polymer; The cable has a content of the acrylic polymer of more than 12.5 parts by mass and less than 20 parts by mass per 100 parts by mass of the vinyl chloride resin.

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