Polyvinyl chloride resin composition, electric wires and cables using the same

Abstract

To provide a polyvinyl chloride resin composition that effectively inhibits the generation of hydrogen chloride gas during combustion, while offering both oil resistance and electric characteristics.SOLUTION: A polyvinyl chloride resin composition comprises: a first stabilizer comprising at least one of zinc stannate and zinc borate; a second stabilizer with a specific surface area of 2.2 m2 / g or more, comprising calcium carbonate surface-treated with fatty acid; and a plasticizer comprising at least one of trimellitic acid ester and pyromellitic acid ester. Relative to 100 pts.mass of polyvinyl chloride resin, the first stabilizer is 10 pts.mass or more and 20 pts.mass or less, and the second stabilizer is 45 pts.mass or more and 65 pts.mass or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a polyvinyl chloride resin composition, and electric wires and cables using the same. [Background technology]

[0002] Polyvinyl chloride (PVC) resin is inexpensive, produced in large quantities, and its physical properties 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 plasticizer. For these reasons, it is widely used as an industrial resin material in applications such as piping and pipe components, construction materials, automotive components, adhesives, various films, surface materials for wallpaper and leather, tubes, and insulation for electric wires and cables.

[0003] In the application of polyvinyl chloride (PVC) resin as a base material for insulators and sheaths (outer layers) to electric wires and cables, its many advantages—including high electrical insulation, flame retardancy, chemical resistance, water resistance, and colorability—have made it widely used for a long time, in addition to its cost-effectiveness. One of the important physical properties of such a coating material is flexibility, and the desired softness is imparted to PVC resin by adding a relatively large amount of plasticizer.

[0004] As a vinyl chloride resin applied to such coating materials, for example, a vinyl chloride resin composition is known in which trimellitic acid ester and phthalic acid ester are mixed in a predetermined ratio as a plasticizer (see, for example, Patent Document 1).

[0005] On the other hand, in recent years, with increasing demand for environmental considerations, phthalate esters, including bis(2-ethylhexyl) phthalate, which are widely used as plasticizers for polyvinyl chloride resins, have raised concerns about adverse effects on humans, such as carcinogenicity and reproductive toxicity. As a result, the European REACH regulation is also tending to expand the types of compounds and uses that are subject to regulation. Furthermore, since polyvinyl chloride resins generate toxic hydrogen chloride gas when burned, the amount of hydrogen chloride gas generated in electric wires and cables is regulated according to their intended use.

[0006] In response to these trends, the application of plasticizers and various additives for polyvinyl chloride resins that can replace phthalate esters is being considered, and efforts to reduce environmental impact are continuing. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2013-129776 [Overview of the project] [Problems that the invention aims to solve]

[0008] To minimize environmental impact, particularly in efforts to suppress hydrogen chloride gas generation during combustion, methods such as adding large amounts of fine inorganic fillers have been reported. However, when applied to electric wires and cables, it is necessary to not only highly suppress hydrogen chloride gas generation but also to satisfy various required properties as a coating material. It has been found that when large amounts of inorganic fillers are incorporated, a decrease in oil resistance and electrical properties tends to become a problem.

[0009] The object of the present invention is to provide a vinyl chloride resin composition that combines oil resistance and electrical properties while highly suppressing the generation of hydrogen chloride gas during combustion. Other purposes and novel features will become apparent from the description and accompanying drawings herein. [Means for solving the problem]

[0010] A brief overview of some of the representative embodiments disclosed in this application is as follows:

[0011] The vinyl chloride resin composition of the present invention comprises a vinyl chloride resin having a degree of polymerization of 1300 or more, a first stabilizer containing at least one of zinc stannate and zinc borate, and a specific surface area of ​​2.2 m². 2The material contains a second stabilizer comprising calcium carbonate surface-treated with fatty acids at a concentration of 10 / g or more, and a plasticizer comprising at least one of trimellitic acid ester and pyromellitic acid ester, wherein the material contains 10 to 20 parts by mass of the first stabilizer and 45 to 65 parts by mass of the second stabilizer per 100 parts by mass of the vinyl chloride resin.

[0012] The electric wire of the present invention comprises a conductor and an insulating layer covering the conductor, wherein the insulating layer comprises a polyvinyl chloride resin having a degree of polymerization of 1300 or more, a first stabilizer containing at least one of zinc stannate and zinc borate, and a specific surface area of ​​2.2 m². 2 The vinyl chloride resin composition comprises a second stabilizer containing calcium carbonate surface-treated with fatty acids at a concentration of 10 / g or more, and a plasticizer containing at least one of trimellitic acid ester and pyromellitic acid ester, wherein the composition contains 10 to 20 parts by mass of the first stabilizer and 45 to 65 parts by mass of the second stabilizer per 100 parts by mass of the vinyl chloride resin.

[0013] The present invention relates to a cable comprising a conductor, an insulating layer covering the conductor, and a covering layer covering the insulating layer, wherein the covering layer comprises a polyvinyl chloride resin having a degree of polymerization of 1300 or more, a first stabilizer containing at least one of zinc stannate and zinc borate, and a specific surface area of ​​2.2 m². 2 The vinyl chloride resin composition comprises a second stabilizer containing calcium carbonate surface-treated with fatty acids at a concentration of 10 / g or more, and a plasticizer containing at least one of trimellitic acid ester and pyromellitic acid ester, wherein the composition contains 10 to 20 parts by mass of the first stabilizer and 45 to 65 parts by mass of the second stabilizer per 100 parts by mass of the vinyl chloride resin. [Effects of the Invention]

[0014] The vinyl chloride resin composition of the present invention provides a material that combines oil resistance and electrical properties while highly suppressing the generation of hydrogen chloride gas during combustion.

[0015] The electric wires and cables of the present invention can have both oil resistance and electrical properties while highly suppressing the generation of hydrogen chloride gas during combustion.

Brief Description of the Drawings

[0016] [Figure 1] It is a schematic cross-sectional view of an electric wire, which is an embodiment of the present invention. [Figure 2] It is a schematic cross-sectional view of a cable, which is an embodiment of the present invention. [Figure 3] It is a diagram showing a schematic configuration of an extruder that performs a cable manufacturing (extrusion) process used in an example.

Modes for Carrying Out the Invention

[0017] Hereinafter, embodiments will be described in detail with reference to the drawings. In all the drawings for explaining the embodiments, members having the same function are denoted by the same reference numerals, and repeated explanations thereof are omitted. In the following embodiments, explanations of the same or similar parts are not repeated in principle unless particularly necessary.

[0018] <Vinyl Chloride Resin Composition> The vinyl chloride resin composition of the present embodiment contains a vinyl chloride resin, a plasticizer, and a stabilizer as essential components. Hereinafter, each component will be described in detail.

[0019] (Vinyl Chloride Resin) The vinyl chloride resin used here is a known vinyl chloride resin used for this type of resin, and is a polymer obtained by polymerizing vinyl chloride (CH2=CHCl) as a monomer. In the present embodiment, those having a number average polymerization degree of 1300 or more are used. The number average polymerization degree is calculated by the method defined in JIS K 6720-2.

[0020] Generally, compounds for wire insulation are kneaded using kneaders, Banbury mixers, or extruders, and when forming wires or cables, they are extruded into the conductor or wire using an extruder to coat it. At this time, by setting the number average degree of polymerization of the polyvinyl chloride resin to 1300 or higher, the kneading and coating processes described above can be carried out without problems. If this number average degree of polymerization is lower than 1300, the viscosity of the material decreases, reducing the dispersibility of additives and increasing the amount of adhesive on the equipment, thus reducing processability and making it more likely that problems will occur that prevent the manufacturing of wires or cables.

[0021] By setting the number-average degree of polymerization of the polyvinyl chloride resin to between 1700 and 2500, an appropriate material viscosity can be imparted, resulting in a polyvinyl chloride resin composition with excellent kneading processability.

[0022] (Stabilizer) The stabilizer used here is primarily for suppressing the generation of hydrogen chloride gas during the combustion of the resin composition. In this embodiment, a first stabilizer containing at least one of zinc stannate or zinc borate, and a particle with a specific surface area of ​​2.2 m² 2 This method involves using a second stabilizer containing calcium carbonate that is present in a quantity of 1g or more and whose surface is treated with fatty acids.

[0023] By incorporating at least one of zinc stannate and zinc borate as the first stabilizer, a char covering the entire material can be formed during the combustion of the resin composition, preventing hydrogen chloride gas from being released outside the system. The preferred amount of these stabilizers is approximately 10 to 20 parts by mass per 100 parts by mass of vinyl chloride resin, balancing the suppression of hydrogen chloride gas generation with oil resistance.

[0024] By using an amount of 10 parts by mass or more, sufficient char can be generated, and by using an amount of 20 parts by mass or less, the oil resistance required for wire coatings can be satisfied. However, it is preferable to avoid using materials containing many hydroxyl groups, such as zinc hydroxystainate, for wire coatings, as these tend to reduce electrical insulation properties.

[0025] As the second stabilizer, by adding calcium carbonate with a specific surface area of 2.2 m 2 / g or more and surface-treated with a fatty acid, hydrogen chloride gas generated during combustion can be efficiently captured.

[0026] The specific surface area of these calcium carbonate particles is preferably 2.4 m 2 / g or more and 3.2 m 2 / g or less. Here, in this specification, the specific surface area can be determined by the air permeability method.

[0027] As this calcium carbonate, its particle size is preferably 0.5 to 1.5 μm, and it is effective to use fine particle calcium carbonate with a particle size of about 1.0 μm or less (particularly, about 0.75 μm or more and 0.95 μm or less), and hydrogen chloride gas generated during combustion can be efficiently captured. Here, the particle size refers to the average particle size calculated by the following formula from the specific surface area determined by the air permeability method (the density of calcium carbonate is 2.71 g / cm 3 ). Average particle size [μm] = 6 / (specific surface area [m 2 / g] × density [g / cm 3 )

[0028] However, if the particles are small (the specific surface area is large), they tend to aggregate between calcium carbonate particles, leading to a decrease in the hydrogen chloride gas capture ability and oil resistance. Therefore, surface treatment with a fatty acid suppresses these property degradations.

[0029] The fatty acids used here are saturated or unsaturated medium-chain (carbon number 6 to 12) and long-chain fatty acids (carbon number 13 or more), for example, stearic acid, lauric acid, palmitic acid, myristic acid, caprylic acid, capric acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, etc. Fatty acid esters obtained by reacting these with an alcohol may also be used. In addition, if an anti-aggregation effect can be obtained with a surface treatment agent other than a fatty acid (for example, a silane coupling agent), it is applicable.

[0030] The amount of calcium carbonate added is preferably 45 to 65 parts by mass, and more preferably 47 to 62 parts by mass, per 100 parts by mass of vinyl chloride resin. If it exceeds 65 parts by mass, the oil resistance may decrease, and if it is less than 45 parts by mass, the hydrogen chloride gas scavenging ability may not be sufficiently obtained.

[0031] (Plasticizer) The plasticizer used here is a component that imparts flexibility to the vinyl chloride resin composition, making it easier to process. In this embodiment, the plasticizer includes at least one of trimellitic acid ester and pyromellitic acid ester.

[0032] By including at least one of trimellitic acid esters and pyromellitic acid esters, the use of phthalate-based esters, which are of environmental concern, can be avoided, and electrical insulation and heat aging resistance can be improved, making it particularly useful for wire coatings.

[0033] Examples of trimellitic acid esters include tris-2-ethylhexyl trimellitic acid, isononyl trimellitic acid, and mixed linear alkyl trimellitic acid esters. Examples of pyromellitic acid esters include 2-ethylhexyl pyromellitic acid and mixed linear alkyl pyromellitic acid esters, and these may be mixed.

[0034] Furthermore, by using trimellitic acid tris-2-ethylhexyl ester (TOTM) as the trimellitic acid ester, phthalate esters can be replaced with general-purpose non-phthalate esters as plasticizers, which is particularly economically advantageous.

[0035] (Additives) The vinyl chloride resin composition of this embodiment may contain various additives, as long as they do not impair the effects of the present invention. Such additives may include antioxidants, insulation improvers, flame retardants, and other additives.

[0036] Suitable antioxidants include phenolic antioxidants and amine antioxidants. Suitable phenolic antioxidants include 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-(4'-hydroxy-3',5'-di-tert-butylphenyl)propionic acid (CAS No. 2082-79-3), octyl-3,5-di-tert-butyl-4-hydroxy-hydrocinnamic acid (CAS No. 125643-61-0), and 2,4-bis[(dodecylthio)methyl]-6-methylphenol (CAS No. 110675-26-8), 3,6-dioxaoctane-1,8-diyl=bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate] (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 (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), 3-(4'-hydroxy-3',5'-di-tert-butylphenyl)propionic acid-n-octadecyl (CAS No. 2082-79-3), 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'''-methanetetrayltetraphenol (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'-bis-3-(3'5'di-t-butyl-4'-hydroxyphenyl)propionylhexamethylenediamine (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), bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid][ethylenebis(oxyethylene)] (CAS Examples of compounds that can be cited include No. 36443-68-2), 2,6-di-tert-butyl-4-methylphenol (CAS No. 128-37-0), 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 N,N'-bis[2-[2-(3,5-di-tert-butyl-4-hydroxyphenyl)ethylcarbonyloxy]ethyl]oxamide (CAS No. 70331-94-1). Furthermore, sulfur-containing compounds include pentaerythritol tetrakis[3-(dodecylthio)propionic acid] (CAS No. 29598-76-3) and 3,3'-thiobispropionic acid ditridecyl (CAS By using compounds such as No. 10595-72-9 in combination, excellent antioxidant functions can also be achieved.

[0037] Examples of amine-based antioxidants include poly(1,2-dihydro-2,2,4-trimethylquinoline) (CAS No. 26780-96-1), ethoxyquin (CAS No. 91-53-2), reaction product of diphenylamine and acetone (CAS No. 68412-48-6), N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine (CAS No. 793-24-8), N-isopropyl-N'-phenylbenzene-1,4-diamine (CAS No. 101-72-4), N,N'-di-2-naphthyl-1,4-phenylenediamine (CAS No. 93-46-9), 4'-anilinotoluene-4-sulfonanilide (CAS No. 100-93-6), and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine (CAS Examples of compounds that can be used include those listed in CAS No. 10081-67-1, di(4-octylphenyl)amine (CAS No. 101-67-7), and N-phenyl-1-naphthylamine (CAS No. 90-30-2), with pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], a phenolic antioxidant, being particularly useful. These compounds can be used individually, in combination of two or more, in mixtures, or in masterbatches mixed with resins; there are no restrictions on their addition method.

[0038] As an example of an insulating agent, we can mention the Insurite LHM series manufactured by Mizusawa Chemical Industries, which is a clay-containing compound.

[0039] As a flame retardant, antimony oxide is preferred because it can be expected to improve flame retardancy when used in combination with halogen elements contained in polyvinyl chloride resin. Specifically, antimony oxide, antimony trioxide, and antimony pentoxide can be mentioned, with antimony trioxide being particularly useful.

[0040] In order to achieve the function of a wire covering material, other additives such as lubricants, surfactants, inorganic and organic fillers, reinforcing materials, fillers, crosslinking agents, crosslinking aids, silane coupling agents, compatibilizers, copper degradation inhibitors, ultraviolet absorbers, light stabilizers, and colorants may also be used.

[0041] (Preparation of vinyl chloride resin composition) A vinyl chloride resin composition can be prepared by mixing and melt-kneading the components described above. Kneading can be carried out using known kneading equipment, such as batch kneaders like Banbury mixers or pressure kneaders, or continuous kneaders like twin-screw extruders.

[0042] The vinyl chloride resin composition obtained as described above suppresses the amount of hydrogen chloride gas generated during combustion and is a resin composition that combines high oil resistance and electrical properties. In particular, the amount of hydrogen chloride gas generated as defined in JCS 7397-4 is 100 mg / g or less, the tensile elongation remaining after immersion in IRM902 oil at 85°C for 4 hours is 60% or more, and the volume resistivity in a 60°C atmosphere is 2.0 × 10⁻⁶. 12 By providing a polyvinyl chloride resin composition with properties of Ω·cm or higher, it becomes possible to provide a wire coating material with excellent electrical properties while achieving high levels of suppression of hydrogen chloride gas generation and oil resistance.

[0043] <Electric wire> The electric wire in this embodiment has an insulating layer made of the polyvinyl chloride resin composition described above. As an example of this electric wire, as shown in Figure 1, an electric wire 1 can be provided in which the outer circumference of a conductor 2 is covered with an insulating layer 3, in which case the insulating layer 3 is made of the polyvinyl chloride resin composition described above.

[0044] Here, conductor 2 can be any commonly used metal wire, such as copper wire, copper alloy wire, aluminum wire, gold wire, or silver wire. Alternatively, conductor 2 may be a metal wire with a metal plating such as nickel applied to its circumference. Furthermore, a stranded conductor, made by twisting metal wires together, can also be used as conductor 2.

[0045] Figure 3 is a schematic diagram showing an example of an extruder for manufacturing electric wires in this embodiment. As shown in Figure 3, the extruder 11 comprises a cylinder 20, a screw 13 rotatably mounted within the cylinder 20, a hopper 12 for supplying material into the cylinder 20, and a crosshead 16. The extruder 11 also comprises a neck 15 between the crosshead 16 and the screw 13, and a breaker plate 14 between the neck 15 and the screw 13. The crosshead 16 has a die 17, and a conductor 18 (conductor 2) passing through the crosshead 16 is covered with an insulating layer within the crosshead 16, passes through the die 17, and is drawn out from the crosshead 16 as an electric wire 19 (electric wire 1).

[0046] <Cable> Furthermore, the electric wires 1 shown in Figure 1 can be bundled together individually or in groups to form a cable. An example of such a cable is the cable 10 shown in Figure 2, in which the outer circumference of a conductor 2 is covered with an insulating layer 3, and the outer circumference of the electric wire is further covered with a sheath layer 4.

[0047] In this cable 10, the insulating layer 3 may be made of an insulating material commonly used as an insulating layer for electric wires, such as polyvinyl chloride, fluororesin, crosslinked polyethylene, natural rubber, or synthetic rubber. Alternatively, the insulating layer 3 may be made of the polyvinyl chloride resin composition described above.

[0048] The covering layer (sheath) 4 is made of the polyvinyl chloride resin composition described above. When bundling multiple electric wires, they can be bundled together with the intermediary, and a sealing tape can be applied to the outer circumference to form the covering layer (sheath) 4 as the outermost layer.

[0049] As a method for manufacturing this cable, the conductor 2 is replaced with the electric wire 1 in the electric wire manufacturing method described above, and the cable 10 can be manufactured by forming a covering layer (sheath) on the outer circumference of the electric wire 1 using an extruder in the same manner, thereby coating it with the polyvinyl chloride resin composition described above. [Examples]

[0050] Next, this embodiment will be described in detail with reference to examples and comparative examples.

[0051] (Examples 1-10, Comparative Examples 1-11) The mixing of polyvinyl chloride resin and various additives, the preparation of sheets for characterizing the polyvinyl chloride resin composition, and the fabrication of electric wires and cables using the polyvinyl chloride resin composition were carried out as follows. Note that the following conditions are examples only and are not limiting.

[0052] [Mixing of polyvinyl chloride resin and various additives] All the polyvinyl chloride resin and various additives were weighed into a stainless steel container according to the formulations shown in Tables 2 to 4, and left at room temperature until the plasticizer was sufficiently impregnated (until the entire mixture was dry). The materials in the stainless steel container were stirred and then placed into a 6-inch diameter twin-screw machine heated to a roll surface temperature of 175°C. The mixture was kneaded for 5 minutes with a roll gap of approximately 1 mm to produce a polyvinyl chloride resin composition.

[0053] [Creation of a characteristic evaluation sheet] Using a press molding machine, the kneaded polyvinyl chloride resin composition was heated and pressurized at 180°C for 5 minutes to form a sheet with a thickness of 1 mm, thereby obtaining a sheet for characterization.

[0054] [Wire manufacturing] Electric wires were manufactured using a 65mm single-screw extruder. The extruder settings are shown in Table 1. Multiple strands of tin-plated soft copper wire were twisted together to form a conductor with a cross-sectional area of ​​1.25 mm². 2 A vinyl chloride resin composition was extruded onto the conductor to a thickness of 0.78 mm as an insulator.

[0055] To achieve the above mixing, any commonly used mixing device other than a roll press, such as an extruder, kneader, mixer, or autoclave, is acceptable, and the mixing conditions are not limited to those described above. Similarly, the manufacture of electric wires is just one example; an electric wire (a conductor covered with an insulator) can be extruded to form a cable, and the extrusion conditions, conductor and insulator materials, and electric wire and cable structures are not limited to those described above.

[0056] [Table 1]

[0057] [Table 2]

[0058] [Table 3]

[0059] [Table 4]

[0060] The materials used in Tables 2 to 4 are as follows: *1: TH-1000 (for soft materials) (manufactured by Taiyo Vinyl Co., Ltd.), *2: TH-1300 (manufactured by Taiyo Vinyl Co., Ltd.), *3: TH-1700 (manufactured by Taiyo Vinyl Co., Ltd.), *4: TH-2500 (manufactured by Taiyo Vinyl Co., Ltd.), *5: Trimex T-08 (manufactured by Kao Corporation), *6: Irganox 1010 (manufactured by BASF), *7: Antimony trioxide (Twinkling *8: Star Co., Ltd., *9: Insulite LHM-103HP (Mizusawa Chemical Co., Ltd.), *10: Alkanex ZS (Mizusawa Chemical Co., Ltd.), *11: Alkanex ZHS (Mizusawa Chemical Co., Ltd.), *12: Lighton A (Bihoku Funka Kogyo Co., Ltd.; fatty acid treated), *13: Lighton BS-O (Bihoku Funka Kogyo Co., Ltd.; fatty acid treated), *14: Lighton BS-OX (Bihoku Funka Kogyo Co., Ltd.; fatty acid treated), *15: Lighton 32X (Bihoku Funka Kogyo Co., Ltd.; fatty acid treated)

[0061] [Characteristics] The amount of gas generated during combustion, tensile properties, oil resistance, and electrical properties of the polyvinyl chloride resin composition were evaluated using the above-mentioned property evaluation sheet as follows. The results obtained are shown in Tables 2 to 4.

[0062] [Amount of hydrogen chloride gas generated] A hydrogen chloride gas generation test was conducted as specified in JCS 7397-4. The hydrogen chloride gas generated when 0.5 g of a sheet piece cut to approximately 1 mm square was burned in a heating tube at 800°C for 30 minutes was quantitatively titrated as follows: Five gas suction tubes (without filters) filled with 50 mL of water were connected together according to section J of 4.4.3, and the generated hydrogen chloride gas was collected. 250 mL of the collected water, along with 50 mL of water used to wash each absorption tube (a total of 300 mL), titration reagents (iron and silver ion reagents), and isoamyl alcohol were placed in an Erlenmeyer flask, and titration was performed with ammonium thiocyanate. After adding ammonium thiocyanate and stirring, the endpoint was reached when color development (red coloration due to the formation of iron thiocyanate) continued for 3 seconds. The test was performed with n=1, and the amount of hydrogen chloride gas generated per unit amount of the vinyl chloride resin composition was determined using the following formula.

[0063] Hydrogen chloride gas generation rate (mg / g) = 3.65 (BA) × (300 / 50) / C In the formula, symbols A, B, and C represent the following: A: Volume of ammonium thiocyanate titration (mL) when a vinyl chloride resin composition is burned. B: Titration volume of ammonium thiocyanate when empty-bed (without sample) (mL) C: Amount of vinyl chloride resin composition added (g)

[0064] Here, products with a hydrogen chloride gas generation amount of 100 mg / g or less were deemed acceptable (○), while those exceeding 100 mg / g were deemed unacceptable (×). Furthermore, products with a hydrogen chloride gas generation amount of 95 mg / g or less were deemed to have particularly high levels of hydrogen chloride gas suppression (◎).

[0065] [Tensile properties] Using a Tensilon-type small tensile testing machine STA-1225 (manufactured by Orientec Co., Ltd.), a sheet shaped like a Type 2 dumbbell test specimen (with gauge marks at 25 mm intervals) as described in JIS K6723 was pulled at a speed of 200 mm / min, and the elongation was calculated from the length between the gauge marks at the time of fracture using the following formula. The test was performed with n=3, and the average value was taken as the characteristic value. Elongation (%) = ((Gauge length at break (mm) - 25) / 25) × 100

[0066] [Oil resistance properties] A sheet shaped like a No. 2 dumbbell test specimen as described in JIS K 6723 was immersed for 4 hours in test oil (IRM902 oil: manufactured by Nippon Sun Oil Co., Ltd.) heated to 85°C. After wiping off the test oil adhering to the surface, the sheet was stored at room temperature (23°C) for 24 hours. After marking with a gauge line as in the tensile test described above, it was pulled at a speed of 200 mm / min, and the elongation was determined from the length between the gauge lines at the time of fracture. The test was performed with n=3, and the average value was used as the characteristic value. The oil resistance characteristic (remaining elongation) was calculated using the following formula.

[0067] Elongation percentage (%) = (Elongation after immersion in test oil (%) / Elongation determined by tensile properties (%)) × 100 Products with an elongation retention rate of 60% or more as an indicator of oil resistance were deemed to pass (〇), while those with an elongation retention rate of less than 60% were deemed to fail (×).

[0068] [Electrical characteristics] The volume resistivity was calculated by measuring the current value after 1 minute of applying a DC voltage of 500V to the sheet in a constant temperature chamber set to 60℃ using an ultra-high insulation resistance meter R8340A (manufactured by ADVANTEST).

[0069] Considering its applicability to wire insulation materials, the volume resistivity is 2.0 × 10⁻⁶. 12 Items with a diameter of Ω·cm or greater are considered acceptable (〇), 2.0 × 10 12 Values ​​less than Ω·cm were considered unacceptable (×).

[0070] [Workability] Furthermore, the processability during roll mixing was sensory-evaluated at each stage of the process. Mixing operations were classified as follows: none of the problems were observed (◎), some concerns were present but the work was still possible (〇), and the processability was poor and the work was difficult (×). ◎ or 〇 were considered passing grades, and × were considered failing grades. During the wire manufacturing process, we visually inspected for any operational defects during the insulation extrusion and checked the appearance of the surface of the manufactured wires.

[0071] [Evaluation of characteristics] Vinyl chloride resin compositions were prepared using the material formulations shown in Tables 2 and 3, and their properties were evaluated as follows based on the properties obtained as described above.

[0072] The evaluation criteria included the amount of hydrogen chloride gas generated during combustion, oil resistance (residual elongation after immersion in test oil), electrical properties, and processability during mixing. A comprehensive evaluation was conducted, with a product passing all criteria, and failing even one criterion resulting in a failure.

[0073] In the production of electric wires using the formulations shown in the examples, no problems were observed in terms of workability, similar to the usual process of extruding and coating with a polyvinyl chloride resin composition. Furthermore, the appearance of the electric wire holding surface coated with the polyvinyl chloride resin composition of this embodiment was smooth, and no abnormalities such as blemishes were observed.

[0074] From the examples, the degree of polymerization of the polyvinyl chloride resin was set to 1300 or higher, the amount of the first stabilizer added was 10 parts by mass or more and 20 parts by mass or less, and the specific surface area of ​​the calcium carbonate surface-treated with fatty acid was set to 2.2 m². 2 It was found that setting the concentration to / g suppresses the amount of hydrogen chloride gas generated during combustion and allows for control of oil resistance and electrical insulation properties to the desired characteristics. The vinyl chloride resin and compounding additives used in this embodiment are not limited in any way.

[0075] <Basis for optimal conditions> Comparative Examples 1 and 2 showed that when the first stabilizer was not added or was added in small amounts of 5 parts by mass or less, a large amount of hydrogen chloride gas was generated during combustion, and the required properties could not be satisfied. This is thought to be because there was no or insufficient char formation from the first stabilizer during combustion, and a large amount of hydrogen chloride gas detached from the vinyl chloride resin was discharged into the system. Furthermore, when the amount of the first stabilizer was increased to 25 parts by mass from Comparative Example 3, the oil resistance deteriorated and the product failed the test. This is presumed to be due to an excessively high filler filling rate.

[0076] From Comparative Example 4, the specific surface area of ​​the calcium carbonate particles is 1.2 m². 2 It was found that when the value was small ( / g), a large amount of hydrogen chloride gas was generated, and the required characteristics could not be satisfied. This is thought to be because the capture of the generated hydrogen chloride gas was insufficient, and a large amount of hydrogen chloride gas was discharged outside the system.

[0077] Comparative Example 5 showed that using zinc hydroxystainate as a substitute for zinc stainate was highly effective in suppressing hydrogen chloride gas generation, similar to zinc stainate. However, it was shown that the electrical insulation properties decreased, failing to meet the requirements. It is presumed that the hydroxyl groups of zinc hydroxystainate are hydrophilic, making them more likely to adsorb moisture from the atmosphere, thus reducing electrical insulation properties.

[0078] Comparative Example 6 showed that when a polyvinyl chloride resin with a degree of polymerization of 1000 was used as the base material, the viscosity of the polyvinyl chloride resin composition was low, making it difficult to sufficiently knead (disperse) the additives, and thus it was not possible to produce characteristic evaluation sheets or electric wires.

[0079] Examples 9-10 and Comparative Examples 7-11 showed that when the content of the second stabilizer was low (40 parts by mass or less), a large amount of hydrogen chloride gas was generated, and the required properties could not be satisfied. This is thought to be because the generated hydrogen chloride gas was not adequately captured, and a large amount of hydrogen chloride gas was discharged outside the system. On the other hand, when the content of the second stabilizer was high (70 parts by mass or more), the elongation rate deteriorated, the oil resistance decreased, and the product failed the test. This is presumed to be due to an excessively high filler filling rate.

[0080] From the above results, it was found that a material that combines the high oil resistance and electrical properties required for wire and cable coatings while highly suppressing hydrogen chloride gas generation during combustion can be obtained by adjusting and optimizing the degree of polymerization of the base polyvinyl chloride resin, the type of plasticizer, the addition of zinc stannate or zinc borate, and the addition of surface-treated calcium carbonate having a predetermined specific surface area.

[0081] This embodiment demonstrates that a polyvinyl chloride resin composition can be obtained that satisfies the high-level properties required for wire and cable coatings while also considering environmental impact. This polyvinyl chloride resin composition significantly reduces the amount of hydrogen chloride gas generated during combustion and exhibits extremely high oil resistance. Therefore, it is particularly suitable for applications where safety against combustion and smoke emission is strongly required, and for applications where there is a high possibility of contact with machine oil, etc. Although this material is intended for use as a wire coating, it can be broadly applied to other product applications with similar requirements.

[0082] Although the present inventors have described the invention in detail based on embodiments above, it goes without saying that the present invention is not limited to the above embodiments and can be modified in various ways without departing from its essence. [Explanation of Symbols]

[0083] 1 electric wire 2 conductors 3. Insulating layer 4. Coating layer (sheath) 10 Cables 11 Extruder 12 Hoppers 13 Screw 14 Breaker Plate 15 neck 16 Crosshead 17 dice 18 Conductors 19 Electric wire 20 cylinders

Claims

1. A polyvinyl chloride resin having a degree of polymerization of 1300 or more, A first stabilizer containing zinc stannate, Specific surface area is 2.2 m² ２ A second stabilizer containing calcium carbonate surface-treated with fatty acids, at a concentration of 1g or more, A plasticizer comprising at least one trimellitic acid ester and pyromellitic acid ester, A vinyl chloride resin composition comprising 10 to 20 parts by mass of the first stabilizer and 45 to 65 parts by mass of the second stabilizer, per 100 parts by mass of the vinyl chloride resin.

2. In the vinyl chloride resin composition according to claim 1, A vinyl chloride resin composition in which the trimellitic acid ester is tris-2-ethylhexyl trimellitic acid.

3. In the vinyl chloride resin composition according to claim 1, A vinyl chloride resin composition in which the content of the first stabilizer is 12.5 parts by mass or more and 20 parts by mass or less.

4. In the vinyl chloride resin composition according to claim 1, The specific surface area of ​​the second stabilizer is 2.4 m². ２ / g or more 3.2m ２ A vinyl chloride resin composition having a concentration of less than or equal to / g.

5. In the vinyl chloride resin composition according to claim 1, The vinyl chloride resin composition has a hydrogen chloride gas generation amount of 100 mg / g or less as defined in JCS 7397-4, a tensile elongation retention of 60% or more after immersion in IRM No. 902 oil at 85°C for 4 hours, and a volume resistivity of 2.0 × 10 in a 60°C atmosphere. １２ A vinyl chloride resin composition having properties of Ω·cm or greater.

6. In the vinyl chloride resin composition according to claim 1, A vinyl chloride resin composition wherein the degree of polymerization of the vinyl chloride resin is 1700 or more and 2500 or less.

7. In the vinyl chloride resin composition according to claim 1, Furthermore, a vinyl chloride resin composition comprising a phenolic compound as an antioxidant, a clay-containing compound as an insulating agent, and an antimony oxide compound as a flame retardant.

8. In the vinyl chloride resin composition according to claim 1, A polyvinyl chloride resin composition for use as a covering for electric wires or cables.

9. An electric wire comprising a conductor and an insulating layer covering the conductor, wherein the insulating layer comprises a polyvinyl chloride resin having a degree of polymerization of 1300 or more, a first stabilizer containing zinc stannate, and a specific surface area of ​​2.2 m². ２ An electric wire comprising a vinyl chloride resin composition containing a second stabilizer containing calcium carbonate surface-treated with fatty acids at a concentration of 10 parts by mass or more / g, and a plasticizer containing at least one of trimellitic acid ester and pyromellitic acid ester, wherein the composition contains 10 parts by mass or more and 20 parts by mass or less of the first stabilizer and 45 parts by mass or more and 65 parts by mass or less of the second stabilizer per 100 parts by mass of the vinyl chloride resin.

10. In the electric wire described in claim 9, The vinyl chloride resin composition has a hydrogen chloride gas generation amount of 100 mg / g or less as defined in JCS 7397-4, a tensile elongation retention of 60% or more after immersion in IRM No. 902 oil at 85°C for 4 hours, and a volume resistivity of 2.0 × 10 in a 60°C atmosphere. １２ Electric wires with characteristics of Ω·cm or higher.

11. A cable comprising a conductor, an insulating layer covering the conductor, and a covering layer covering the insulating layer, The coating layer comprises a polyvinyl chloride resin having a degree of polymerization of 1300 or more, a first stabilizer containing zinc stannate, and a specific surface area of ​​2.2 m². ２ A cable comprising a vinyl chloride resin composition containing a second stabilizer containing calcium carbonate surface-treated with fatty acids at a concentration of 10 parts by mass or more / g, and a plasticizer containing at least one of trimellitic acid ester and pyromellitic acid ester, wherein the composition contains 10 parts by mass or more and 20 parts by mass or less of the first stabilizer and 45 parts by mass or more and 65 parts by mass or less of the second stabilizer per 100 parts by mass of the vinyl chloride resin.

12. In the cable according to claim 11, The vinyl chloride resin composition has a hydrogen chloride gas generation amount of 100 mg / g or less as defined in JCS 7397-4, a tensile elongation retention of 60% or more after immersion in IRM No. 902 oil at 85°C for 4 hours, and a volume resistivity of 2.0 × 10 in a 60°C atmosphere. １２ A cable with characteristics of Ω·cm or higher.

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