JP2010116465A - Resin material for electric wire/cable or connector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin material for electric wire/cable or a connector that hardly causes deterioration of a conductor or a plastic material though obtained using a plant-derived substance and is soft, very extendible and highly water-resistant. <P>SOLUTION: The resin material used for insulating electric wire, cable or a connector formed at the end thereof comprises a plastic material as a base material and, incorporated therewith, lignin as well as a metal, a metal hydroxide or a metal oxide of at least a chemical equivalent amount necessary for neutralizing an acidic substance remaining in the lignin. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electric wire / cable or connector resin material using lignin.

  Petroleum-derived materials such as polyolefin-based materials and polyvinyl chloride are widely used as covering materials for electric wires and cables. This is because the material has characteristics required as a wire covering material, that is, it is soft and stretches well and has high water resistance and flame retardancy.

  On the other hand, along with recent environmental problems and the shift to a resource recycling society, there is an active movement to reduce the use of petroleum-derived materials and apply plant-derived materials (biomass-derived materials) to household appliances and automotive parts. It has become. The most typical polymer derived from plants is, for example, polylactic acid.

  As an example of applying such a plant-derived material to an electric wire, for example, an intermediate tape in which a resin component made of a plant-derived material is blended as a filler with respect to a base material made of a plastic material is prepared. Some are applied to electric wires (see, for example, Patent Document 1).

JP 2007-42521 A Japanese Patent Laid-Open No. 11-152410

  However, since the above plant-derived materials are generally hard and brittle and have low water resistance, there is a problem that it is difficult to satisfy the characteristics required as a wire coating material.

  In Patent Document 1, the reason why the plant-derived material is applied to the intervening tape is that the intervening tape is not required to have the characteristics of being soft and well stretched and having high water resistance as required for the covering material of the electric wire. It is.

  That is, conventionally, when a plant-derived material is applied to an electric wire, its use is limited to a narrow range, and it has been difficult to use it as a covering material for an electric wire. Therefore, a new technology that can widely use plant-derived materials as a covering material for electric wires is demanded.

  By the way, there is lignin as a plant-derived material. Lignin is also called a wood element and is present in a plant-derived material such as wood or rice straw in combination with cellulose.

  When blending this lignin into a plastic material, it is necessary to separate and remove the lignin from the cellulose in advance. For example, by separating the lignin bound to the cellulose with sulfuric acid, the cellulose is separated to produce lignosulfonic acid. Or a process of taking lignophenol out by preferentially decomposing cellulose with acid or alkali. In addition, lignin extracted by decomposing lignin in wood with alkali in the pulp and paper manufacturing process may be used.

  However, acidic substances remain in the lignin separated by the acid or alkali treatment. For this reason, when lignin is blended with a plastic material, the remaining acidic substance promotes hydrolysis of the main chain and side chain of the plastic material, leading to deterioration.

  Furthermore, if a resin material containing lignin containing an acidic substance is applied to an insulation coating material or connector for an electric wire or cable, the metal (conductor, etc.) around the resin material is oxidized, and the electric wire, cable, or connector There is also a problem in that the conductor used in the process is deteriorated.

  Accordingly, an object of the present invention is to provide a resin material for electric wires / cables or connectors that uses a plant-derived substance, does not deteriorate conductors and plastic materials, is soft and stretches well, and has high water resistance. .

  The present invention has been devised to achieve the above object, and the invention of claim 1 is a resin material used for an insulated wire, a cable, or a connector formed on a terminal thereof, and has a base. Electric wires / cables that contain lignin in the plastic material, and a metal, metal hydroxide, or metal oxide in excess of the chemical equivalent necessary to neutralize the acidic substances remaining in the lignin. Or it is the resin material for connectors.

  The invention according to claim 2 is the resin for electric wires, cables or connectors according to claim 1, wherein the aspect ratio of the lignin particles is 1.5 or more and the length of the long side of the lignin particles is 2 mm or less. Material.

  The invention according to claim 3 is the resin material for electric wires / cables or connectors according to claim 1 or 2, wherein the lignin is esterified with a hydroxyl group of phenol existing in the skeleton thereof.

  The invention according to claim 4 is the resin for electric wire / cable or connector according to claim 3, wherein the hydroxyl group of phenol existing in the lignin skeleton is esterified by treating the lignin with a supercritical alcohol. Material.

  ADVANTAGE OF THE INVENTION According to this invention, the resin material for electric wires, cables, or a connector which does not deteriorate a conductor and a plastic material, uses a plant-derived substance, is soft and can be extended, and has high water resistance can be obtained.

  Hereinafter, preferred embodiments of the present invention will be described.

  The resin material for electric wires / cables or connectors according to the present embodiment is used for insulated wires, cables, connectors formed on their terminals, etc., and lignin (or lignin) is used as a plastic material as a base material. And a metal, metal hydroxide, or metal oxide in excess of the chemical equivalent necessary to neutralize the acidic substance remaining in the lignin. .

  Plastic materials used for the base material include polyethylene, ethylene propylene rubber, ethylene butene binary or terpolymer, polypropylene, vinyl acetate, acrylic acid, methacrylic acid ester, propylene, etc. It is preferable to use one or two or more types obtained by grafting a functional group containing maleic anhydride or epoxy to a polymer or polyolefin. In this embodiment, EVA (ethylene vinyl acetate copolymer) is used.

  Lignin is present in a plant-derived material such as wood or rice straw in combination with cellulose.For example, by decomposing lignin bound to cellulose with sulfuric acid, cellulose can be separated and taken out as lignosulfonic acid, Cellulose may be preferentially decomposed with acid or alkali and taken out as lignophenol. Or you may use what decomposed | disassembled and extracted the lignin in wood with an alkali in the manufacturing process of paper pulp.

  After the lignin is taken out, the taken out lignin may be subjected to a hydrophobic treatment to esterify the hydroxyl group of phenol present in the skeleton.

  Since the phenol in the lignin skeleton has a hydroxyl group which is a hydrophilic group, if it is directly blended into a plastic material, there may be a problem in water resistance. Therefore, the hydroxyl group of the hydrophilic group is chemically modified using an esterification reaction or the like to make it hydrophobic.

  When performing the hydrophobic treatment, it is preferable to carry out the hydrophobic treatment without using a catalyst such as a metal compound or a halogen substance. This is because the resin material for electric wires / cables or connectors is used as an environmentally compatible product. Therefore, in the present embodiment, in order to carry out the esterification reaction without using a catalyst, the hydrophobic treatment was performed using a highly reactive alcohol in a supercritical state.

  The aspect ratio of the lignin particles is preferably 1.5 or more, and the length of the long side of the lignin particles is preferably 2 mm or less.

  In general, magnesium hydroxide and hydrotalcite used as fillers usually have to be used after being pulverized to about 10 microns because the mechanical properties of the plastic material as the base material are reduced when the particle size is large. is there. However, in order to make lignin into particles as small as 10 microns or less as in the case of a normal compounding agent (filler), it takes time to grind.

  Therefore, as a result of studying the size of lignin particles to be blended, the present inventors have found that when lignin is blended into a plastic material, the aspect ratio is 1.5 or more and the long diameter (long side length) It has been found that no problem arises in mechanical properties even when large particles of about 2 mm are blended.

  This is probably because the adhesion between lignin and a plastic material and between lignin and a metal (metal, metal hydroxide, or metal oxide) is very strong. Since lignin has functional groups such as hydroxyl and carbonyl groups, it acts as a compatibilizer for metals (metals, metal hydroxides, or metal oxides) and metal salts and plastic materials. In addition, it is considered that there is an effect of adhering well to metal.

  In the resin material for electric wires / cables or connectors according to this embodiment, a metal, metal hydroxide, or metal oxide having a chemical equivalent or more necessary for neutralizing the acidic substance remaining in lignin is blended.

  The chemical equivalent required to neutralize acidic substances remaining in lignin is the molar amount necessary to neutralize acidic substances remaining in lignin (such as lignosulfonic acid) extracted using sulfuric acid. That is.

  The chemical equivalent required to neutralize the acidic substance remaining in the lignin is obtained, for example, by dispersing the extracted lignin (such as lignosulfonic acid) in water and neutralizing the water. If neutralization is determined in this way, the molar amount (normality) of the acidic substance remaining in the lignin can be determined, so that the metals and metals necessary to neutralize this depending on the molar amount The amount of hydroxide or metal oxide can be determined.

  Examples of the metal include group II elements such as magnesium and calcium, group VIII elements such as cobalt and iron, zinc, Ti, and mixtures thereof.

  Examples of the metal hydroxide include magnesium hydroxide, aluminum hydroxide, calcium hydroxide, and these metal hydroxides in which nickel is dissolved, and these are used alone or in combination of two or more. Further, an appropriate amount of another metal hydroxide may be added. These metal hydroxides may be surface-treated with a silane coupling agent, a titanate coupling agent, a stearate, a fatty acid such as calcium stearate, or a fatty acid metal salt. In the present embodiment, magnesium hydroxide is used as the metal hydroxide.

  Examples of the metal oxide include magnesium oxide, calcium oxide, iron (II) oxide, and zinc oxide.

Moreover, in the resin material for electric wires / cables or connectors according to this embodiment, a commonly used sulfur-based or sulfuric acid-based antioxidant may be added. For example, 2,2-thio-diethylenebis [ 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl 3 -(3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1 , 3,5-triazine, bis [2-methyl-4-{3-n-alkyl (C ₁₂ or C ₁₄₎ thio propionyloxy} -5-t-butylphenyl] sulfide, 4, One to two or more kinds selected from 4′-thiobis (3-methyl-6-tert-butylphenol) may be added in an amount of 0.05 to 15 parts by mass. Thus, the heat aging characteristics can be improved.

Furthermore, 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], pentaerythrityl-tetrakis [3- (3,5-di-t-butyl) -4-hydroxyphenyl) propionate], octadecyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2,4-bis- (n-octylthio) -6- (4-hydroxy-3 , 5-di -t- butylanilino) -1,3,5-triazine, bis [2-methyl-4-{3-n-alkyl (C ₁₂ or C ₁₄₎ thio propionyloxy} -5-t-butylphenyl 0.05 to 15 parts by mass of one or more selected from sulfide and 4,4′-thiobis (3-methyl-6-tert-butylphenol), and dilaurylthiodi 0.05 to 15 parts by mass of one or two selected from lopionate, dimyristylthiodipropionate, distearylthiodipropionate, ditridecylthiodipropionate, and tetrakis (methylenedodecylthiopropionate) methane May be added. Thereby, a remarkable synergistic effect can be expected and the heat aging characteristics can be further improved. Furthermore, deterioration of the plastic material due to contact with metal, so-called metal damage can be prevented.

  Carbon black for imparting weather resistance may be added, and additives such as a lubricant, a colorant, and an inorganic filler may be added.

  After blending lignin and metal, metal hydroxide, or metal oxide in a plastic material to obtain a resin material for electric wires, cables, or connectors, for example, this is put into an extruder and heated by an extruder. When extrusion molding is performed on the outer periphery of the conductor while kneading, an electric wire (or cable) is obtained. Alternatively, a connector can be obtained by heating and kneading the obtained electric wire / cable or connector resin material and molding it by a predetermined method. In this heating and kneading step, it is considered that lignin and metal (metal, metal hydroxide, or metal oxide), and interaction (adhesion action) between lignin and a plastic material are developed.

  The operation of this embodiment will be described.

  In the resin material for electric wires / cables or connectors according to this embodiment, lignin is added to the plastic material, and a metal or metal hydroxide having a chemical equivalent or more necessary for neutralizing the acidic substance remaining in the lignin. Products or metal oxides.

  As a result, the acidic substance remaining in the lignin is neutralized, so that there is no problem of deteriorating the plastic material or oxidizing the surrounding metal (conductor etc.).

  Furthermore, since lignin adheres well to plastic materials and metals (metals, metal hydroxides, or metal oxides) by heating and kneading, it is possible to obtain good tensile strength and elongation.

  That is, according to the present invention, it is possible to realize a resin material for an electric wire / cable or connector that does not deteriorate a conductor or a plastic material and that is soft and stretched while using lignin, which is a plant-derived substance.

  In the present embodiment, as the lignin, one having an aspect ratio of the particle of 1.5 or more and a long side length of the particle of 2 mm or less is used.

  As a result, an excessive pulverization step of lignin is not necessary, and costs can be suppressed.

  Furthermore, in the present embodiment, as the lignin, one obtained by esterifying the hydroxyl group of phenol existing in the skeleton is used.

  Thereby, since the hydroxyl group which is a hydrophilic group is esterified and becomes hydrophobic, water resistance can be improved.

  In the present embodiment, the hydrophobic treatment is performed by treating lignin with supercritical alcohols.

  As a result, the hydrophobic treatment can be performed without using a catalyst, so that the resin material for electric wires / cables or connectors can be used as an environmentally compatible product.

  Examples of the present invention will be described below.

  Using EVA (ethylene vinyl acetate copolymer) as a plastic material, blending lignin and metal hydroxide (magnesium hydroxide) in a predetermined ratio to EVA, for the wires / cables or connectors of Examples 1-7 A resin material was prepared. Further, as comparative examples, resin materials of Comparative Example 1 in which lignin was not blended and Comparative Examples 2 and 3 in which magnesium hydroxide was not blended were prepared. Table 1 summarizes the formulations of Examples 1 to 7 and Comparative Examples 1 to 3.

  In the examples, the chemical equivalent required to neutralize the acidic substance remaining in lignin is determined by the following method.

100 g of lignin is immersed in 500 ml of water, heated to 60 ° C. and held for 4 hours. The amount of NaOH for neutralizing the amount of acidic components contained in 100 g of lignin is determined by neutralizing and titrating the acidic component extracted into water with NaOH. The chemical equivalent of Mg (OH) ₂ for neutralizing 100 g of lignin is determined by the molecular weight of Mg (OH) ₂ × the molar amount of NaOH required for neutralization / 2.

  In Table 1, lignin 1 is lignosulfonic acid, a lignin-derived substance obtained by decomposing the cellulose component of sawdust with concentrated sulfuric acid. Lignin 2 is lignosulfonic acid obtained by decomposing cellulose with dilute sulfuric acid.

  As the lignin, an elongated shape having a maximum length of 2 mm and an aspect ratio of 1.5 to 500 was used. This is a shape that is easy to take when cellulose is separated from the wood by a chemical.

  In Table 1, in the tensile test, oxygen index, and water resistance evaluation, each resin material was kneaded with a 120 ° C. roll for 3 minutes, then formed into a sheet with a roll, and press molded at 180 ° C. In the heat-kneading process, it is considered that the interaction between lignin and metal hydroxide and between lignin and plastic material is expressed.

  The tensile test was evaluated based on JIS C3005. If the tensile strength was 8 MPa or more, it was rated as ◯, and if it was less than 8 MPa, it was marked as x. The elongation was rated as ○ if it was 200% or more, and x if it was less than 200%.

  Moreover, the oxygen index was evaluated based on JIS K7201 as an index of flame retardancy. The target oxygen index was set to 24.0, more than this passed, and less than 24.0 failed.

  As an indicator of water resistance, the appearance was evaluated by immersing in warm water at 90 ° C. for 24 hours. The case where the sheet does not change is indicated by ◯, the case where the surface is roughened by water absorption of lignin is indicated by Δ, and the case where the sheet surface shape is changed is indicated by ×. At that time, “◯” and “Δ” were judged to be acceptable levels for practical use, and were accepted.

In the evaluation of the discoloration of the conductor, each resin material was extruded onto a 2 mm ² annealed copper stranded wire to a thickness of 0.8 mm. This was placed in water at 90 ° C., and the change in the color of the conductor was observed.

  In addition, in the evaluation of environmental compatibility, a plant-derived substance (lignin) containing 10 parts by mass or more with respect to 100 parts by mass of a base polymer (plastic material) was marked with ◯, and less than that with x.

  The lignin was treated with ethanol in a supercritical state of 340 ° C. and 10 MPa for 30 minutes.

  As shown in Table 1, in Examples 1 to 7, in the tensile test, the tensile strength is 8 MPa or more, the elongation is 200% or more, and the flame resistance is also 24.0 or more and the extrusion processability is also good. Met. The water resistance was not a big problem in Examples 1 and 2, although the surface was rough.

  Furthermore, in Examples 3 and 4 using ethanol-treated lignin, the water resistance was further improved, and the surface could be kept smooth after the test.

  On the other hand, in Comparative Example 1 in which lignin was not blended, environmental compatibility was unacceptable. In Comparative Examples 2 and 3 in which magnesium hydroxide was not blended, the conductor was affected by the influence of acidic substances contained in lignin. Oxidized and the color of the conductor changed.

  From the above experimental results, by adding lignin to the plastic material and adding magnesium hydroxide more than the chemical equivalent necessary to neutralize the acidic substance remaining in the lignin, elongation, tensile strength, flame resistance As a result, it was confirmed that an electric wire / cable or connector resin material suitable for the environment could be obtained without any discoloration of the conductor.

Claims (4)

A resin material used for an insulated wire, a cable, or a connector formed on a terminal thereof,
In addition to blending lignin into the plastic material, which is the base material, blending metal, metal hydroxide, or metal oxide in excess of the chemical equivalent necessary to neutralize the acidic substances remaining in the lignin. Characteristic resin material for electric wires / cables or connectors.   2. The resin material for an electric wire / cable or connector according to claim 1, wherein an aspect ratio of the lignin particles is 1.5 or more and a length of a long side of the lignin particles is 2 mm or less.   3. The resin material for electric wires / cables or connectors according to claim 1, wherein the lignin is obtained by esterifying a hydroxyl group of phenol existing in a skeleton thereof.   The resin material for electric wires / cables or connectors according to claim 3, wherein the hydroxyl group of phenol existing in the lignin skeleton is esterified by treating the lignin with an alcohol in a supercritical state.