JP5609780B2 - Electric wires and cables using silane-crosslinked polyolefin compositions - Google Patents

Description

The present invention has been crosslinked by the use of new silanol condensation catalyst in place of the organic tin compounds environmental hormone action is concerned, relates to wire and cable using the silane-crosslinked polyolefin composition.

  Graft copolymerization of an organic silane compound with a polyolefin such as polyethylene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer in the presence of a free radical generator, or the obtained graft copolymer or polyethylene and vinylsilane In order to obtain a molded product by molding a copolymer of a compound into a predetermined shape, a silane-crosslinked polyolefin composition in which moisture is allowed to act under a silanol condensation catalyst, thereby cross-linking between molecules is widely used. ing.

  This cross-linking method, called silane water cross-linking, causes a small amount of organic peroxide to act on the polyolefin as a graft initiator in a molding machine such as an extruder, thereby grafting a silane compound such as vinylalkoxysilane onto the polyolefin. After polymerization, the graft copolymer discharged from the molding machine is exposed to high temperature and high humidity or warm water to cause a crosslinking reaction.

  The crosslinking reaction is caused by hydrolysis and condensation reaction of alkoxysilane by the action of a silanol condensation catalyst (mainly an organic tin compound) mixed in advance in the graft copolymer or penetrating from the surface of the graft copolymer. The basis of the reaction is to link the molecules of the polymer by causing hydrolysis and condensation reaction to the alkoxysilane graft-copolymerized to the polymer, thereby promoting crosslinking. This cross-linking method is simple and low-cost both in terms of equipment and process, compared to the so-called chemical cross-linking method in which only organic peroxides are used for cross-linking. It is optimal as a method for crosslinking molded products such as

Japanese Patent Laid-Open No. 04-013737 JP 2004-189946 A

  However, according to the silane-crosslinked polyolefin composition based on the conventional silane crosslinking as in Patent Document 1, there is a concern about environmental hormones in the organotin compound used as a silanol condensation catalyst, so there are concerns about the future in terms of safety. Has been. That is, among the organotin compounds, triphenyltin and tributyltin have already been specified as substances having an environmental hormone action that disturbs the endocrine function of the human body. The dibutyltin compound being used is likely to receive the same designation.

  In recent years, there has been a tendency to require further simplification of the production process and equipment, and it has been required to exhibit sufficient crosslinking characteristics in a state of being left in a room temperature atmosphere without being exposed to high temperature and high humidity or hot water. Yes.

  Moreover, since the inorganic tin compound as in Patent Document 2 is inferior in catalytic ability to the organic tin compound, when used alone as a silanol condensation catalyst, sufficient crosslinking characteristics can be obtained when left at room temperature. Have difficulty.

Therefore, the object of the present invention is to use an electric wire / silica that uses a silanol condensation catalyst in place of an organotin compound, which is feared of harmfulness, and a silane-crosslinked polyolefin composition that can obtain a crosslinking rate equivalent to that of the organic tin compound as an insulator. To provide a cable .

Invented in order to solve the above problems, the present invention insulates a silane-crosslinked polyolefin composition, which is formed of a polyolefin composition having hydrolyzable silyl groups in the side chain and crosslinks the polyolefin by acting moisture. In the wire / cable used as a body, as a silanol condensation catalyst for promoting crosslinking of the polyolefin, one or more inorganic tin compounds in which tin atoms and carbon atoms are not directly bonded are 0.005 per 100 parts by mass of the polyolefin. The polyolefin is crosslinked by adding 0.005 parts by mass or more and 0.5 parts by mass or less of 100 parts by mass or more of an organic acid compound as a co-catalyst. It is an electric wire / cable characterized by

  The inorganic tin compound may be at least one compound selected from a dicarboxylic acid tin compound and a tin diketonate compound.

  The organic acid compound may be at least one compound selected from carboxylic acid, phosphite, sulfonic acid, and carboxylic anhydride.

According to the present invention, there is provided an electric wire / cable that uses a silanol condensation catalyst instead of an organotin compound, which is feared of harmfulness, and uses a silane-crosslinked polyolefin composition capable of obtaining a crosslinking rate equivalent to that of the organotin compound as an insulator. Can be provided.

It is a figure which shows the electric wire and cable which used the silane crosslinked polyolefin composition as an insulator.

  Hereinafter, a preferred embodiment of the present invention will be described in detail.

The silane-crosslinked polyolefin composition used in the present invention is formed of a polyolefin composition having a hydrolyzable silyl group in the side chain, and the crosslinking of the polyolefin is accelerated in the silane-crosslinked polyolefin composition in which the polyolefin is crosslinked by the action of moisture. As a silanol condensation catalyst for the catalyst, one or more inorganic tin compounds in which tin atoms and carbon atoms are not directly bonded are 0.005 parts by mass or more and 0.5 parts by mass or less per 100 parts by mass of polyolefin, and one kind as a co-catalyst. The above-mentioned organic acid compound is a silane-crosslinked polyolefin composition obtained by adding 0.005 parts by mass or more and 0.5 parts by mass or less per 100 parts by mass of polyolefin to crosslink the polyolefin.

  In the present invention, the reason for limiting the amount of the inorganic tin compound used as the silanol condensation catalyst to 0.005 parts by mass or more and 0.5 parts by mass or less with respect to 100 parts by mass of the polyolefin is that the polyolefin is less than 0.005 parts by mass. On the other hand, when the amount exceeds 0.5 parts by mass, an early crosslinking reaction occurs in a molding machine such as an extruder, and a molded product with a good appearance is obtained. By not getting.

Examples of inorganic tin compounds include tin (II) stearate, tin (II) oleate, tin (II) acetate,
Examples thereof include dicarboxylic acid tin compounds such as tin bisneodecanoate and bis (2-ethylhexanoic acid) tin, and tin diketonate compounds such as tin (II) 2,4 pentadionate and acetylacetonate tin (II). Of these, tin bisneodecanoate, bis (2-ethylhexanoate) tin, and tin (II) 2,4-pentanedionate are preferred because they exhibit excellent crosslinking properties and are easily available.

  In the present invention, the reason why the amount of the organic acid compound used as a co-catalyst for the silanol condensation catalyst is limited to 0.005 parts by mass or more and 0.5 parts by mass or less with respect to 100 parts by mass of the polyolefin is 0.005 parts by mass. If less than 0.5 parts by weight, it is insufficient in quantity to crosslink between the polyolefin molecules. On the other hand, if exceeding 0.5 parts by mass, an early crosslinking reaction occurs in a molding machine such as an extruder, and the appearance This is because a good molded product cannot be obtained.

  Examples of the organic acid compound include a carboxylic acid compound, a phosphite compound, a sulfonic acid compound, and a carboxylic acid anhydride.

  The carboxylic acid compound is not particularly limited, but formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, lauric acid, tetradecanoic acid, stearic acid And aliphatic carboxylic acids such as oleic acid, and aromatic carboxylic acids such as salicylic acid, benzoic acid and phthalic acid.

  The phosphite compound is not particularly limited, but trimethyl phosphite, triethyl phosphite, tributyl phosphite, tri (2-ethylhexyl) phosphite, tributoxyethyl phosphite, trioleyl phosphite, tristearyl phosphite, Triisodecyl phosphite, triphenyl phosphite, tricresyl phosphite, trixylenyl phosphite, tris (isopropylphenyl) phosphite, trisnonylphenyl phosphite, tris (o-phenylphenyl) phosphite, tris (p -Phenylphenyl) phosphite, trinaphthyl phosphite, cresyl diphenyl phosphite, xylenyl diphenyl phosphite, diphenyl (2-ethylhexyl) phosphite, di (iso Ropirufeniru) phenyl phosphite, o- phenylphenyl dicresyl phosphite, dibutyl phosphite, monobutyl phosphite, di-2-ethylhexyl phosphite, monoisodecyl phosphites and condensates thereof and the like.

  The sulfonic acid compound is not particularly limited, and examples thereof include alkylsulfonic acids such as methanesulfonic acid, ethanesulfonic acid, and propanesulfonic acid, and aromatic sulfonic acids such as benzenesulfonic acid, toluenesulfonic acid, and dodecylbenzenesulfonic acid. .

  The carboxylic acid anhydride is not particularly limited, and examples thereof include acetic anhydride, propionic anhydride, succinic anhydride, maleic anhydride, phthalic anhydride, trimellitic anhydride, and pyromellitic dianhydride.

  As the polyolefin, a polymer material mainly composed of polyethylene polymerized by an ion polymerization method, polyethylene polymerized by a radical polymerization method, or a mixture of an ion polymerization polyethylene and a radical polymerization polyethylene can be used. In addition to these polyethylenes, ethylene copolymers such as ethylene-ethyl acrylate copolymers, ethylene-vinyl acetate copolymers, ethylene-methacrylate copolymers, copolymers of propylene and ethylene, and maleic anhydride to polyolefins And those containing one or more of grafted functional groups containing epoxy and the like can be used.

  As a method for introducing a hydrolyzable silyl group, for example, an alkoxysilyl group, into a side chain of polyolefins, there is a method of grafting vinyl alkoxysilane such as vinyltrimethoxysilane or vinyltriethoxysilane. Initiators for graft copolymerization include dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne, 2,5-dimethyl-2,5- (t-butyl). Peroxy) hexane, α, α'-bis (t-butylperoxy-m-isopropyl) benzene, m- (t-butylperoxyisopropyl) -isopropylbenzene, p- (t-butylperoxyisopropyl) -isopropyl Organic peroxides such as benzene are mainly used.

  Two or more types of radical generators can be used in combination, and the amount added to the polyolefin is preferably set to 0.03 parts by mass or more and 0.15 parts by mass or less. When the addition amount is less than 0.03 parts by mass, it is difficult to obtain a sufficient degree of crosslinking. Conversely, when the addition amount exceeds 0.15 parts by mass, voids resulting from decomposition products of radical generators are generated. Absent.

  In addition to the above method, a polyolefin having an alkoxysilyl group in the side chain can also be obtained by copolymerizing a polyolefin and a vinylalkoxysilane compound.

  Moreover, you may add compounding agents, such as antioxidant for improving the heat-resistant aging characteristic according to the objective.

  Antioxidants added to improve heat aging characteristics include 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 (C12 or C14) ) Thiopropionyloxy} -5-tert-butylphenyl] sulfide, 4,4′-thiobis (3-methyl-6-tert-butylphenol) It is preferable. The addition amount is in the range of 0.05 parts by mass or more and 0.5 parts by mass or less per 100 parts by mass of the polyolefin.

  In addition to the above antioxidants, dilauryl thiodipropionate, dimyristyl thiodipropionate, distearyl thiodipropionate, ditridecyl thiodipropionate, tetrakis (methylene dodecyl thiodipropionate) methane An embodiment in which one or more selected antioxidants are used in combination is also preferable, and a preferable addition amount of these mixed antioxidants is also 0.05 parts by mass or more and 0.5 parts by mass with respect to 100 parts by mass of the polyolefin. Set to:

  When the two groups of antioxidants listed above are used in combination, the anti-aging effect is synergistically improved compared to the case where the antioxidants of the above-mentioned groups are used alone, and further, contact with metal It is also possible to effectively suppress metal damage, which is degradation of polyolefin due to.

  These antioxidants may be added in the form of a dry blend with respect to the polyolefin, or a master batch in which these antioxidants are mixed in the polyolefin at a high concentration may be added.

  Further, it can be dissolved in a silane compound and mixed with polyolefin in a molding machine such as an extruder together with the addition of the silane compound.

  The reason why it is preferable to set the addition amount of the antioxidant to 0.05 parts by mass or more and 0.5 parts by mass or less as described above is that when it is less than 0.05 parts by mass, The reason is that sufficient results cannot be obtained for the metal damage prevention effect in the case of combined use, and if the amount exceeds 0.5 parts by mass, an antioxidant is deposited on the surface of the molded product, so-called bloom phenomenon occurs. deep.

  The silane-crosslinked polyolefin composition of the present invention described above has great utility as an alternative to a silane-crosslinked polyolefin composition using an organotin silanol condensation catalyst that is a concern for environmental hormones.

  The following two methods are conceivable as production means when the silane-crosslinked polyolefin composition of the present invention is applied to the use of electric wires or cables. That is, one of them is a two-shot or Sioplus that is prepared by preparing a masterbatch containing a high concentration of a silanol condensation catalyst and a co-catalyst, and feeding it to an extruder together with a polyolefin previously grafted with a silane compound. The other is a method in which an additive containing a silane compound, a silanol condensation catalyst, a co-catalyst, and a radical initiator is supplied to the polyolefin in the extruder, whereby the graft reaction of the silane compound to the polyolefin This is a one-shot or monosilic method in which cable extrusion is simultaneously performed by one extruder.

  Examples and comparative examples will be described.

   FIG. 1 shows an example of the configuration of an electric wire / cable to which the silane-crosslinked polyolefin composition of the present invention is applied. In this example, a silane-crosslinked polyethylene insulator 2 is formed on a conductor 1.

  Table 1 summarizes the contents of Examples 1 to 10 and Comparative Examples 1 to 7 of the present invention and the evaluation of these implementation results.

In Examples 1 to 10 and Comparative Examples 1 to 7 in Table 1, first, polyethylene is put into a 130 mm extruder at 200 ° C., and vinyltrimethoxysilane in which other components are dissolved immediately before extrusion is used as a hopper of the extruder. By injecting from the lower part of the cable, extrusion molding of the cable and graft copolymerization of the silane compound onto polyethylene were simultaneously performed. This cable has the configuration shown in FIG. 1, and the size of the conductor 1 of the annealed copper stranded wire and the thickness of the silane-crosslinked polyethylene insulator 2 are 38 mm ² and 1.2 mm, respectively.

  Among the displayed components, components that are hardly soluble in vinyltrimethoxysilane were previously mixed into polyethylene by dry blending.

  For evaluation of environmental compatibility, those containing no substances that are likely to cause environmental hormonal effects in the blend composition were judged as good, and those containing were judged bad, and x was listed in Table 1.

  The evaluation of extrusion moldability is the result of visual observation and evaluation of the surface of the extruded insulating coating layer, where ◯ means good and x means bad, which is rough like a crust.

  Next, after leaving the cable in an atmosphere of 80 ° C. and 95% RH for 24 hours or in an atmosphere of 25 ° C. and 65% RH for 7 days, the gel fraction of the silane crosslinked polyethylene insulator 2 is measured in accordance with JISC3005. did. A gel fraction of 70% or more is judged as good, and a gel fraction less than 70% is judged as bad.

  According to Table 1, 0.005 parts by mass or more and 0.5 parts by mass or less of tin bisneodecanoate tin, which is a dicarboxylic acid compound, or tin (II) 2,4-pentanedionate, which is a tin diketonate compound, is used as a silanol condensation catalyst. As a catalyst, 0.005 parts by mass or more of maleic anhydride, which is a carboxylic acid anhydride, trioleyl phosphite, which is a phosphite compound, dodecylbenzenesulfonic acid, which is a sulfonic acid compound, and oleic acid, which is a carboxylic acid. Any of Examples 1 to 10 blended in the range of 5 parts by mass or less shows a good extrusion appearance, a good gel fraction after standing for 7 days at 25 ° C. and 65% RH, and has been frequently used so far. It can be seen that it exhibits excellent properties that can be substituted for organotin compound catalysts.

  This means a cross-linked molded product that is free from environmental hormone concerns, and has a great effect on the silane cross-linking field.

  In addition, according to the comparative example carried out for comparison, in Comparative Example 1 using dibutyltin dilaurate as a conventional silanol condensation catalyst, gel fraction and extrusion moldability are good, but dibutyltin dilaurate is Environmental concern is poor due to concern about environmental harm.

  In the case of Comparative Examples 2, 3, 5, and 6 in which the silanol condensation catalyst and the cocatalyst having the specified blending amount are not mixed in the present invention, the addition amount of the silanol condensation catalyst or the cocatalyst is less than the specified amount. Insufficient cross-linking of the gel showed a low gel fraction after standing for 7 days in an atmosphere of 25 ° C. and 65% RH. Further, even in the case of using the above silanol condensation catalyst, in the case of Comparative Examples 4 and 7 in which a larger amount than that of the present invention was mixed, the crosslinking reaction occurred early in the molding machine. In addition, the results are unsatisfactory for the appearance of the insulator after molding. When comparing the properties with these comparative examples, the good properties of the examples are obvious, and the effect of the silane-crosslinked polyolefin composition of the present invention is obvious.

1 Conductor 2 Silane-crosslinked polyethylene insulator

Claims (3)

In an electric wire / cable using a silane-crosslinked polyolefin composition, which is formed of a polyolefin composition having a hydrolyzable silyl group in the side chain and crosslinks the polyolefin by acting moisture, as an insulator ,
As a silanol condensation catalyst for promoting crosslinking of the polyolefin, one or more inorganic tin compounds in which tin atoms and carbon atoms are not directly bonded are 0.005 parts by mass or more and 0.5 parts by mass or less per 100 parts by mass of the polyolefin. the wire or cable, wherein the polyolefin is added one or more organic acid compounds 0.5 parts by mass 0.005 parts by weight per the polyolefin 100 parts by weight cocatalyst is cross-linked. The electric wire / cable according to claim 1, wherein the inorganic tin compound is at least one compound selected from a dicarboxylic acid tin compound and a tin diketonate compound. The electric wire / cable according to claim 1 or 2, wherein the organic acid compound is at least one compound selected from carboxylic acid, phosphite, sulfonic acid, and carboxylic anhydride.