Resin composition, cable or electric wire, and method for producing cable or electric wire

Abstract

To provide a resin composition which does not adversely affect the human body and the environment, can be produced at a low cost without using a large-scale facility, and does not reduce mechanical strength even when a foaming rate is increased, to provide a cable or an electric wire using the resin composition, and to provide a method for producing the cable or the electric wire.SOLUTION: A resin composition includes a base resin, a cellulose fiber, and a plasticizer, wherein a content of the cellulose fiber in the resin composition is 5 to 60 parts by mass with respect to 100 parts by mass of the base resin, and a foaming rate is 3.0% or more and less than 31.0%.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a resin composition, a cable or an electric wire, and a method for producing a cable or an electric wire. [Background technology]

[0002] Foamed-coated electric wires and cables coated with foamed synthetic resins are being studied or put into practical use for the purposes of reducing the weight, improving flexibility, reducing costs, etc. Conventionally, typical methods for manufacturing these foamed-coated electric wires and cables include a method in which a chemical foaming agent such as azodicarbonamide, which decomposes or reacts when heated to generate gas, is mixed with a synthetic resin to cause foaming (chemical foaming method), and a method in which supercritical carbon dioxide gas, nitrogen gas, chlorofluorocarbons, or the like is injected into a resin and foamed by reducing the pressure (physical foaming method) (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-50250 Summary of the Invention [Problem to be solved by the invention]

[0004] Azodicarbonamide, which is commonly contained in chemical foaming agents used in chemical foaming methods, is classified as a Class 5 self-reactive substance, an azo compound, and has a hazard level of II, and may have adverse effects on the human body and the environment.In addition, there are concerns that residual chemical components in foamed synthetic resins produced by chemical foaming methods may reduce the electrical properties of the resin.

[0005] The physical foaming method can produce foamed synthetic resins with high strength and a high expansion rate by reducing the bubble diameter of the foamed synthetic resin produced. However, it has the disadvantage of requiring large-scale equipment, such as equipment to heat carbon dioxide gas or nitrogen gas to a critical state under high temperature and pressure, and equipment to inject the critical gas into the resin, resulting in high running costs.

[0006] Furthermore, foamed resins generally tend to have reduced mechanical strength, such as tensile strength, making it difficult to use foamed resins when high strength is required.

[0007] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a resin composition that does not adversely affect the human body or the environment, can be produced at low cost without using large-scale facilities, and does not reduce mechanical strength even when the foaming rate is increased, a cable or electric wire using the resin composition, and a method for producing the cable or electric wire. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the resin composition according to the present invention has the following characteristics. A resin composition comprising a base resin, cellulose fiber, and a plasticizer, In the resin composition, the content of the cellulose fiber is 5 to 60 parts by mass relative to 100 parts by mass of the base resin, A resin composition having an expansion rate of 3.0% or more and less than 31.0%.

[0009] In order to achieve the above-mentioned object, the cable or wire according to the present invention has the following features. A cable or wire having a conductor and a covering layer that covers the conductor, The cable or wire, wherein the coating layer comprises the resin composition.

[0010] In order to achieve the above-mentioned object, the method for manufacturing a cable or an electric wire according to the present invention is characterized as follows. A method for manufacturing a cable or an electric wire having a conductor and a covering layer that covers the conductor, the coating layer contains a resin composition having an expansion rate of 3.0% or more and less than 31.0%, The manufacturing method includes: Preparing a mixture containing 100 parts by weight of a base resin, 5 to 60 parts by weight of cellulose fiber, and 30 to 80 parts by weight of a plasticizer; extruding the mixture to form the resin composition. A method for manufacturing a cable or wire. [Effects of the Invention]

[0011] The resin composition according to the present invention exhibits a good expansion rate, tensile strength and elongation.

[0012] The present invention has been briefly described above. The details of the present invention will become clearer by reading the following detailed description of the invention (hereinafter referred to as "embodiments") with reference to the accompanying drawings. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic cross-sectional view of a cable according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] Specific embodiments of the present invention will be described below with reference to the drawings.

[0015] [Resin composition] The resin composition in this embodiment is a resin composition containing a base resin, cellulose fiber, and a plasticizer, In the resin composition, the content of the cellulose fiber is 5 to 60 parts by mass relative to 100 parts by mass of the base resin, The resin composition has an expansion rate of 3.0% or more and less than 31.0%.

[0016] (Foaming rate) The resin composition of this embodiment has an expansion ratio of 3.0% or more and less than 31.0%, preferably 5 to 25%, and more preferably 10 to 20%. Because the resin composition of this embodiment has an expansion ratio within the above range, it is lightweight and flexible, similar to conventional expanded resins.

[0017] In this specification, the expansion ratio is a value calculated by the following formula (1). Foaming rate (%) = {(density of resin composition before foaming (kg / m 3 ) - Density of the resin composition after foaming (kg / m 3 )) × 100} / density of resin composition before foaming (kg / m 3 ) ···(1) In the above formula (1), the density is a value measured based on JIS K 7112.

[0018] (cellulose fiber) By using cellulose fiber in the production, the resin composition according to this embodiment has a good foaming ratio. Furthermore, by including cellulose fibers in the resin composition of this embodiment, the strength of the resin composition is improved by the cellulose fibers. Generally, the mechanical strength of a foamed resin composition decreases, but in this embodiment, even if the foaming ratio is 3.0% or more and less than 31.0%, the decrease in the mechanical strength of the resin composition is suppressed.

[0019] In the resin composition, cellulose fiber is preferably contained as a filler. When cellulose fiber is contained as a filler, the purity of the cellulose fiber is preferably 99% or more. In addition to cellulose fiber, the filler may also contain impurities (1% or less).

[0020] The cellulose fiber may be of plant origin or synthetic origin, but is preferably of plant origin. The cellulose fiber may also be chemically modified.

[0021] The cellulose fibers preferably have an average fiber length of 4 to 100 μm, more preferably 30 to 50 μm. Here, the average fiber length is a value measured using an electron microscope. For example, the fiber lengths of fibers in a 100 μm × 100 μm image measured using an electron microscope can be averaged to obtain the average fiber length.

[0022] Examples of cellulose fibers include fluorene cellulose fiber manufactured by Osaka Gas Chemicals Co., Ltd. and cellulose microfiber (CMF) manufactured by Rettenmeyer.

[0023] (base resin) Examples of the base resin include vinyl chloride resins, ethylene-vinyl acetate copolymers, and ethylene-(meth)acrylate copolymers, with vinyl chloride resins being particularly preferred.

[0024] The vinyl chloride resin is not particularly limited, but examples thereof include a homopolymer of vinyl chloride, a copolymer of a vinyl chloride monomer and another monomer copolymerizable with the vinyl chloride monomer, and a graft copolymer in which a polymer other than a polyvinyl chloride resin is graft-copolymerized with a vinyl chloride monomer. The above polyvinyl chloride resins may be used alone or in combination of two or more.

[0025] Examples of other monomers copolymerizable with the vinyl chloride monomer include α-olefins such as ethylene, propylene, and butylene; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as butyl vinyl ether and cetyl vinyl ether; (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, and butyl acrylate; aromatic vinyls such as styrene and α-methylstyrene; and N-substituted maleimides such as N-phenylmaleimide and N-cyclohexylmaleimide. One of the other monomers may be used alone, or two or more may be used in combination.

[0026] The average degree of polymerization of the vinyl chloride resin is preferably 1000 to 2500, more preferably 1000 to 2000. Here, the average degree of polymerization of the vinyl chloride resin is a value measured in accordance with JIS K 6720-2.

[0027] Examples of the base resin include Kanevinyl (registered trademark) S1003 manufactured by Kaneka Corporation and TK-1300 manufactured by Shin-Etsu Chemical Co., Ltd.

[0028] (plasticizer) Known plasticizers can be used. Examples of the plasticizer include high molecular weight plasticizers such as phthalate esters (e.g., dioctyl phthalate (DOP), diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), diundecyl phthalate (DUP) and the like), trimellitate esters (e.g., trioctyl trimellitate (TOTM), tri-normal-octyl trimellitate (TnOTM) and the like), adipate esters (e.g., diisobutyl adipate (DIBA), diisodecyl adipate (DIDA)), phosphates (e.g., triethyl phosphate, tricresyl phosphate), and epoxy polyesters (e.g., epoxidized soybean oil).

[0029] Examples of the plasticizer include DOP and DINP manufactured by ADEKA Corporation or J-Plus Corporation.

[0030] (others) In the resin composition of this embodiment, the content of the cellulose fiber is 5 to 60 parts by mass, preferably 10 to 50 parts by mass, and more preferably 20 to 40 parts by mass, relative to 100 parts by mass of the base resin. When the content of the cellulose fiber is within the above range, the expansion rate of the resin composition of this embodiment is 3.0% or more and less than 31.0%. Increasing the content of the cellulose fiber increases the expansion rate.

[0031] In the resin composition of the present embodiment, the content of the plasticizer is not particularly limited, but may be 30 to 80 parts by mass relative to 100 parts by mass of the base resin.

[0032] The resin composition of the present embodiment may contain various other substances such as fillers, colorants, stabilizers, etc. that are typically used in foam-covered electric wires and foam-covered cables.

[0033] As a preferred polyvinyl chloride resin, the Japanese Industrial Standard (JIS K 6723) specifies a flexible polyvinyl chloride material for use in electric wires and cables. The flexible polyvinyl chloride material is generally used as a composition containing 100 parts by mass of polyvinyl chloride resin, 30 to 100 parts by mass of plasticizer, 1 to 10 parts by mass of stabilizer, 0 to 100 parts by mass of filler, and, as needed, various additives such as lubricants and antioxidants. The use of this flexible polyvinyl chloride resin composition as the insulator and sheath of electric wires and cables is a vinyl-insulated vinyl-sheathed cable specified in JIS C 3342.

[0034] [Cable or wire] The cable or electric wire of this embodiment is a cable or electric wire having a conductor and a covering layer that covers the conductor, and the covering layer contains the resin composition of this embodiment described above.

[0035] The covering layer may directly cover the conductor. Alternatively, the covering layer may cover an insulator layer or layers covering the conductor, i.e., a sheath layer. As an example of this embodiment, there is a cable 1, as shown in FIG. 1, which has a conductor 2, an insulator 3 covering the conductor 2, and a sheath layer 4 covering the insulator 3.

[0036] In the cable of this embodiment, from the viewpoint of allowable current and heat resistance, the diameter of the conductor is preferably 9.2 to 28.5 mm, and more preferably 13.4 to 19.4 mm.

[0037] In the cable of this embodiment, from the viewpoint of mechanical properties, the thickness of the coating layer is preferably 1.4 to 1.6 mm, and more preferably 1.45 to 1.55 mm.

[0038] [Cable or wire manufacturing method] The method for manufacturing a cable or an electric wire according to the present embodiment includes the steps of: A method for manufacturing a cable or an electric wire having a conductor and a covering layer that covers the conductor, the coating layer contains a resin composition having an expansion rate of 3.0% or more and less than 31.0%, The manufacturing method includes: Preparing a mixture containing 100 parts by weight of a base resin, 5 to 60 parts by weight of cellulose fiber, and 30 to 80 parts by weight of a plasticizer; and extruding the mixture to form the resin composition.

[0039] By extruding a mixture containing cellulose fibers, part of the cellulose fibers is thermally decomposed by the heat generated during extrusion, generating carbon dioxide, and forming a coating layer containing a foamed resin composition. Unlike conventional chemical foaming methods, foamed resin compositions can be obtained using cellulose fiber without using chemical foaming agents, which prevents adverse effects on worker health and the environment. Furthermore, by using cellulose fiber for production, the production equipment can be less expensive than that used for conventional physical foaming methods, and running costs can also be reduced.

[0040] As the base resin, cellulose fiber and plasticizer, those previously described in this specification are preferably used.

[0041] The mixture contains 100 parts by mass of base resin, 5 to 60 parts by mass of cellulose fiber, and 30 to 80 parts by mass of plasticizer, preferably 100 parts by mass of base resin, 10 to 50 parts by mass of cellulose fiber, and 30 to 80 parts by mass of plasticizer, and more preferably 100 parts by mass of base resin, 20 to 40 parts by mass of cellulose fiber, and 40 to 60 parts by mass of plasticizer.

[0042] The foaming rate of the resulting resin composition can be adjusted by adjusting the content of cellulose fiber in the mixture.

[0043] The method for preparing the mixture is not particularly limited, and the cellulose fiber and plasticizer may be added to the base resin, the base resin and plasticizer may be added to the cellulose fiber, or the base resin and cellulose fiber may be added to the plasticizer. The order of addition is preferably the base resin, cellulose fiber, and plasticizer. If there are solids and liquids, the order of addition is preferably the solids, followed by the liquid. If there are multiple types of solids and liquids, the order of addition is preferably the solids and liquids with the largest amounts.

[0044] The temperature at which the mixture is extruded may be any temperature normally used in extrusion molding for producing a coating layer for a cable or electric wire, and is preferably 180°C or higher, more preferably 190°C or higher, from the viewpoint of making the foaming ratio of the resulting resin composition 3.0% or higher but less than 31.0%. [Example]

[0045] The present invention will be described in detail below with reference to examples. Example 1 A 19.4 mm diameter conductor was coated with cross-linked polyethylene (XLPE) as insulation. A mixture consisting of 100 parts by weight of polyvinyl chloride resin (Kaneka Corporation's "Kanevinyl (registered trademark) S1003"), 30 parts by weight of plasticizer (DINP) (J-Plus Corporation's "DINP"), 5 parts by weight of cellulose fiber (Rettenmeyer's "ARBOCEL"), and 4 parts by weight of stabilizer (ADEKA Corporation's "RUP-137Y") was melt-extruded in an extruder to produce a foamed cable with a coating layer thickness of 1.5 mm containing the foamed resin composition. The melt-extrusion temperature was 190°C. The resulting resin composition had an expansion rate of 3.0%, a tensile strength of 30 MPa, and an elongation of 240%. The expansion rate, tensile strength, and elongation were measured according to the following methods.

[0046] <Foaming rate> The expansion ratio was calculated based on the following formula (1). Foaming rate (%) = {(density of resin composition before foaming (kg / m 3 ) - Density of the resin composition after foaming (kg / m 3 )) × 100} / density of resin composition before foaming (kg / m 3 ) ···(1) In the above formula (1), the density was measured based on JIS K 7112. The density of the resin composition before foaming was the value measured for the density of the unfoamed resin composition after melt extrusion. The density was measured using an automatic hydrometer manufactured by Toyo Seiki Seisakusho, Ltd. A foaming rate of 3.0% or more and less than 31.0% was evaluated as being good. <Tensile strength> The tensile strength was measured in accordance with JIS K 6723. A universal testing machine manufactured by Intesco Co., Ltd. was used to measure the tensile strength. A tensile strength of 10 MPa or more was evaluated as a good result. <Stretch> Elongation was measured in accordance with JIS K 6723. As with the measurement of tensile strength, a universal testing machine manufactured by Intesco Corporation was used to measure elongation. Tensile strength and elongation were measured simultaneously in one measurement. An elongation of 150% or more was evaluated as a good result.

[0047] (Examples 2 to 12, Comparative Examples 1 to 6) Foamed-coated cables were prepared in the same manner as in Example 1, except that the blending amounts of polyvinyl chloride resin, plasticizer, and cellulose fiber were set to the amounts shown in Tables 1 and 2. The foamed-coated cables were also measured for foaming ratio, tensile strength, and elongation in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0048] [Table 1]

[0049] [Table 2]

[0050] Tables 1 and 2 show that the foamed resin obtained by extrusion molding a mixture containing 100 parts by mass of polyvinyl chloride resin, 5 to 60 parts by mass of cellulose fiber, and 30 to 80 parts by mass of plasticizer exhibits good foaming ratio, tensile strength, and elongation.

[0051] Here, the features of the embodiments of the resin composition, cable or electric wire, and method for producing a cable or electric wire according to the present invention will be briefly summarized and listed below in [1] to [5].

[0052] [1] A resin composition comprising a base resin, cellulose fiber, and a plasticizer, In the resin composition, the content of the cellulose fiber is 5 to 60 parts by mass relative to 100 parts by mass of the base resin, A resin composition having an expansion rate of 3.0% or more and less than 31.0%.

[0053] The resin composition having the above constitution [1] exhibits a good expansion rate, tensile strength and elongation.

[0054] [2] The resin composition according to [1] above, wherein the base resin is a vinyl chloride resin.

[0055] According to the resin composition having the above constitution [2], the above effects of the present invention can be fully exhibited.

[0056] [3] A cable (1) or electric wire having a conductor (2) and a covering layer that covers the conductor (2), A cable (1) or an electric wire, wherein the coating layer contains the resin composition according to the above [1] or [2].

[0057] According to the cable or electric wire having the above configuration [3], the resin composition contained in the covering layer exhibits a good expansion rate, tensile strength, and elongation.

[0058] [4] The cable (1) or electric wire according to the above [3], wherein the covering layer is a sheath layer (4).

[0059] According to the cable or wire having the configuration [4] above, the above-mentioned effects of the present invention can be fully exhibited.

[0060] [5] A method for manufacturing a cable (1) or an electric wire having a conductor (2) and a coating layer that coats the conductor (2), comprising: the coating layer contains a resin composition having an expansion rate of 3.0% or more and less than 31.0%, The manufacturing method includes: Preparing a mixture containing 100 parts by weight of a base resin, 5 to 60 parts by weight of cellulose fiber, and 30 to 80 parts by weight of a plasticizer; extruding the mixture to form the resin composition. A method for manufacturing a cable (1) or an electric wire.

[0061] According to the method for producing a cable or an electric wire having the above configuration [5], the resin composition contained in the covering layer of the produced cable or electric wire exhibits a good expansion rate, tensile strength, and elongation. [Explanation of symbols]

[0062] 1 cable 2 conductors 3. Insulators 4 Sheath layer

Claims

1. A resin composition comprising a base resin, cellulose fiber, and a plasticizer, In the resin composition, the content of the cellulose fiber is 5 to 60 parts by mass relative to 100 parts by mass of the base resin, A resin composition having an expansion rate of 3.0% or more and less than 31.0%.

2. The resin composition according to claim 1 , wherein the base resin is a vinyl chloride resin.

3. A cable or wire having a conductor and a covering layer that covers the conductor, A cable or an electric wire, wherein the coating layer comprises the resin composition according to claim 1 or 2.

4. 4. The cable or wire according to claim 3, wherein the covering layer is a sheath layer.

5. A method for manufacturing a cable or an electric wire having a conductor and a covering layer that covers the conductor, the coating layer contains a resin composition having an expansion rate of 3.0% or more and less than 31.0%, The manufacturing method includes: Preparing a mixture comprising 100 parts by weight of a base resin, 5 to 60 parts by weight of cellulose fiber, and 30 to 80 parts by weight of a plasticizer; and extruding the mixture to form the resin composition. A method for manufacturing a cable or wire.

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