JP5103061B2 - Flame-retardant silane-crosslinked polyolefin resin composition and insulated wire - Google Patents

Description

  The present invention relates to a flame-retardant silane-crosslinked polyolefin resin composition and an insulated wire using the same.

  Conventionally, a vinyl chloride resin composition to which a halogen-based flame retardant is added has been widely used as an insulator for insulated wires used for wiring of vehicle parts such as automobile parts and electrical / electronic equipment parts.

  However, since this type of vinyl chloride resin composition contains a halogen element, it releases harmful halogen-based gases to the atmosphere during combustion such as in the event of a vehicle fire or incineration and disposal of electrical and electronic equipment. There was a problem of causing environmental pollution.

  Therefore, from the standpoint of reducing the burden on the global environment, in recent years, a non-halogen resin that does not contain a halogen element, which is obtained by adding a non-halogen flame retardant such as a metal hydroxide to an olefin resin such as polyethylene. Alternatives to the composition are underway.

  Also, vinyl chloride resin cross-linked electric wires and polyolefin cross-linked electric wires have been used in places that generate high temperatures, such as automobile wire harnesses. The cross-linking method of these electric wires was mainly a method of cross-linking with an electron beam, but the electron beam cross-linking requires an expensive electron beam cross-linking device and the like, the equipment cost is expensive, and the product cost is increased. There was a problem that. Therefore, silane crosslinking that can be crosslinked with inexpensive equipment has attracted attention.

  In order to improve heat resistance, an antioxidant or the like is added to the non-halogenated crosslinked polyolefin resin composition.

  As such a non-halogen type crosslinked polyolefin resin composition, for example, as described in Patent Document 1, a compound obtained by blending a crosslinked polyolefin resin with a phenol-based antioxidant or a phosphorus-based antioxidant, or Patent Document As described in No. 2, a combination of hindered phenol type or thiobisphenol type antioxidants is known.

JP-A-11-181187 Japanese Patent Laid-Open No. 11-255977

  In insulated wires and the like that require heat resistance, it is necessary to add a large amount of an antioxidant to the crosslinked polyolefin resin in order to increase the heat resistance.

  However, when a large amount of antioxidant is added to the polyolefin-based resin, there is a problem that the antioxidant is precipitated (bloomed) on the resin surface and heat resistance is lowered.

  In fields such as automobiles, higher heat resistance may be required, and it has been difficult to improve heat resistance with the conventional non-halogen-based crosslinked polyolefin resin composition described above.

  Therefore, the problem to be solved by the present invention is to provide a flame-retardant silane-crosslinked polyolefin resin composition in which an antioxidant is difficult to bloom and high heat resistance is obtained. Another object is to provide an insulated wire using the flame-retardant silane-crosslinked polyolefin resin composition as an insulator.

  As a result of intensive studies by the present inventors, it is said that by combining a specific antioxidant and a specific bloom inhibitor, a flame-retardant silane-crosslinked polyolefin resin having high heat resistance can be obtained in which the antioxidant is difficult to bloom. Obtained knowledge.

That is, the flame-retardant silane-crosslinked polyolefin resin composition according to the present invention includes a polyolefin resin containing a silane graft polymer obtained by graft polymerization of an olefin resin with a silane coupling agent, a hindered phenol antioxidant, and a semi-hinder. Containing a dophenol antioxidant, a bloom inhibitor composed of zinc oxide and zinc sulfide, a flame retardant composed of a metal hydroxide, and a crosslinking catalyst , the semi-hindered phenol antioxidant is 3, 9-bis [2- {3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5 .5] The main point is that it is undecane .

  Here, the hindered phenol antioxidant is preferably tetrakis- [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane.

  The flame retardant is preferably selected from one or more of magnesium hydroxide, aluminum hydroxide, calcium hydroxide, zirconium hydroxide, and barium hydroxide.

  Furthermore, 0.5 to 10 parts by weight of the hindered phenol-based antioxidant and 0.5 to 10 parts by weight of the semi-hindered phenol-based antioxidant with respect to 100 parts by weight of the polyolefin-based resin containing the silane graft polymer. Part, 0.5-10 parts by weight of the zinc oxide, 0.5-10 parts by weight of the zinc sulfide, and 50-200 parts by weight of the metal hydroxide.

  On the other hand, the insulated wire according to the present invention is characterized by having, as an insulator, a cross-linked polyolefin resin obtained by kneading and heating cross-linking the flame-retardant silane cross-linked polyolefin resin composition.

The flame-retardant silane-crosslinked polyolefin resin composition according to the present invention includes a polyolefin resin containing a silane graft polymer obtained by graft polymerization of an olefin resin with a silane coupling agent, a hindered phenol antioxidant, and a semi-hindered phenol. A semi-hindered phenol-based antioxidant containing 3, 9--, a series antioxidant , a bloom inhibitor composed of zinc oxide and zinc sulfide, a flame retardant composed of a metal hydroxide, and a crosslinking catalyst. Bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5.5 ] undecane der is, a flame-retardant silane-crosslinked polyolefin-based resin obtained by crosslinking it, bloom hardly, high heat resistance can be obtained.

  In addition, the insulated wire according to the present invention has a cross-linked polyolefin resin obtained by kneading and heat-crosslinking the flame retardant silane cross-linked polyolefin resin composition as an insulator, so that it has excellent heat resistance, high temperature load, etc. Can be suitably used for such sites.

  Hereinafter, embodiments of the present invention will be described in detail. The flame-retardant silane crosslinked polyolefin resin composition according to the present invention contains a polyolefin resin, a hindered phenol antioxidant, a semi-hindered phenol antioxidant, a bloom inhibitor, a flame retardant, and a crosslinking catalyst. . First, each component of the flame retardant silane crosslinked polyolefin resin composition according to the present invention will be described.

  The polyolefin resin of the present invention comprises a silane graft polymer obtained by graft polymerization of an olefin resin with a silane coupling agent. For example, a silane graft polymer is prepared by adding a silane coupling agent and a crosslinking agent such as dicumyl peroxide (DCP) to an olefin resin, and heating and kneading and extruding the silane coupling agent using an extruder. It is good to graft polymerize. An olefin resin that is not silane-grafted may be added to the polyolefin resin. In addition, a polypropylene elastomer may be added to the polyolefin resin.

  Examples of the olefin resin include polyolefins such as polyethylene and polypropylene, and ethylene such as ethylene-α olefin copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, and ethylene-methacrylic acid ester copolymer. Exemplifying propylene-based copolymers such as propylene-based copolymers, propylene-α-olefin copolymers, propylene-vinyl acetate copolymers, propylene-acrylic acid ester copolymers, propylene-methacrylic acid ester copolymers Can do. These may be used alone or in combination.

  As the olefin resin, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, and ethylene-methacrylic acid ester copolymer are preferable.

  Examples of polyethylene include high density polyethylene (HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ultra low density polyethylene, and metallocene ultra low density polyethylene. Can do. These may be used alone or in combination. Metallocene ultra-low density polyethylene is preferable.

The density of the olefin resin is preferably 0.901 g / cm ³ or less from the viewpoint of excellent flexibility. However, since the crystallinity of the resin decreases as the density decreases, 0.880 g / cm ³ or more is required from the viewpoint of suppressing swelling of the silane-grafted resin with respect to gasoline and improving gasoline resistance. It is preferable that

Therefore, as the olefin resin, metallocene ultra-low density polyethylene having a density in the range of 0.880 to 0.901 g / cm ³ is particularly preferable. Such metallocene ultra-low density polyethylene may be used alone, or two or more of such metallocene ultra-low density polyethylenes may be used in combination.

  Examples of the silane coupling agent include vinyl alkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, normal hexyltrimethoxysilane, vinylacetoxysilane, γ-methacryloxypropyltrimethoxysilane, γ- Examples thereof include methacryloxypropylmethyldimethoxysilane. These may be used alone or in combination of two or more.

  It is preferable that the compounding quantity of a silane coupling agent exists in the range of 0.5-5 weight part with respect to 100 weight part of olefin resin. More preferably, it is in the range of 3 to 5 parts by weight. When the blending amount of the silane coupling agent is less than 0.5 parts by weight, the graft amount of the silane coupling agent is small and it is difficult to obtain a sufficient degree of crosslinking. On the other hand, if the amount exceeds 5 parts by weight, the cross-linking reaction proceeds too much during kneading, and a gel-like substance is likely to be generated. If it does so, an unevenness | corrugation will be easy to generate | occur | produce on the product surface and mass productivity will deteriorate easily. In addition, the melt viscosity becomes too high, overloading the extruder, and workability tends to deteriorate.

  As the hindered phenol-based antioxidant, tris [(3,5-di-t-butyl-4-bidoxybenzyl) isosialate,], n-octadecyl-3- (3 ′, 5′-di-) Examples thereof include t-butyl-4-hydroxyphenyl) propionate and tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane. Among these, tetrakis- [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane represented by the following chemical formula 1 is preferably used.

  It is preferable that the compounding quantity of a hindered phenolic antioxidant exists in the range of 0.5-10 weight part with respect to 100 weight part of polyolefin resin containing the said silane graft polymer. More preferably, it is in the range of 3 to 5 parts by weight.

  As the semi-hindered phenol-based antioxidant, 3,9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl]- Examples include 2,4,8,10-tetraoxaspiro [5.5] undecane. Among these, 3,9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] represented by the following chemical formula 2 is preferable. -2,4,8,10-tetraoxaspiro [5.5] undecane may be used.

  It is preferable that the compounding quantity of a semi hindered phenolic antioxidant exists in the range of 0.5-10 weight part with respect to 100 weight part of polyolefin resin containing the said silane graft polymer. More preferably, it is in the range of 3 to 5 parts by weight.

  As the bloom inhibitor, zinc oxide and zinc sulfide are used. The blending amounts of zinc oxide and zinc sulfide are preferably in the range of 0.5 to 10 parts by weight with respect to 100 parts by weight of the polyolefin resin containing the silane graft polymer. More preferably, it is in the range of 3 to 5 parts by weight.

  A metal hydroxide is used as the flame retardant. As the metal hydroxide, one or more kinds may be selected from magnesium hydroxide, aluminum hydroxide, calcium hydroxide, zirconium hydroxide, and barium hydroxide.

  It is preferable that the compounding quantity of a metal hydroxide exists in the range of 50-200 weight part with respect to 100 weight part of polyolefin resin containing the said silane graft polymer. More preferably, it is in the range of 70 to 120 parts by weight.

  The crosslinking catalyst is a silanol condensation catalyst that silane-crosslinks a polyolefin resin containing a silane graft polymer obtained by graft polymerization of a silane coupling agent. For example, metal carboxylates such as tin, zinc, iron, lead and cobalt, titanate esters, organic bases, inorganic acids, organic acids and the like can be exemplified.

  Specific examples of the crosslinking catalyst include dibutyltin dilaurate, dibutyltin dimaleate, dibutyltin mercaptide (dibutyltin bisoctylthioglycol ester salt, dibutyltin β-mercaptopropionate polymer, etc.), dibutyltin diacetate, dioctyltin dilaurate , Stannous acetate, stannous caprylate, lead naphthenate, cobalt naphthenate, barium stearate, calcium stearate, tetrabutyl ester titanate, tetranonyl titanate, dibutylamine, hexylamine, pyridine, sulfuric acid, hydrochloric acid , Toluenesulfonic acid, acetic acid, stearic acid, maleic acid and the like. Dibutyltin dilaurate, dibutyltin dimaleate, and dibutyltin mercaptide are preferable.

  The amount of the crosslinking catalyst is a component in the catalyst batch described later, and is preferably blended within the range of 0.5 to 5 parts by weight with respect to 100 parts by weight of the polyolefin resin. More preferably, it is in the range of 1 to 3 parts by weight.

  Next, the insulated wire and the manufacturing method thereof according to the present invention will be described.

  The insulated wire according to the present invention is produced by coating the outer periphery of a conductor with a crosslinked polyolefin resin obtained by kneading water and crosslinking the flame retardant silane crosslinked polyolefin resin composition as an insulator.

  Examples of the material of the conductor used for the insulated wire include annealed copper, tinned annealed copper, copper alloy, aluminum, and aluminum alloy. The conductor diameter is not particularly limited, and can be determined as appropriate according to the application. Moreover, there is no restriction | limiting in particular also about the thickness of an insulator, It can set suitably in consideration of a conductor diameter.

  The insulator coated on the conductor includes a silane graft batch made of a polyolefin resin containing a silane graft polymer obtained by graft polymerization of an olefin resin with a silane coupling agent, a hindered phenolic antioxidant, After kneading and molding a flame retardant batch comprising a hindered phenolic antioxidant, zinc oxide, zinc sulfide, and a metal hydroxide, and a catalyst batch comprising a olefin resin and a crosslinking catalyst, Manufactured by water crosslinking.

  The mixing ratio of the a component (silane graft batch) and the b component (flame retardant batch) is preferably a component: b component = 40: 60 to 10:90. The mixing ratio of the a component and the b component and the c component (catalyst batch) is preferably (a component + b component): c component = 100: 1 to 100: 10.

  The silane graft batch, the flame retardant batch, and the catalyst batch are each prepared separately before molding. At this time, the silane coupling agent and the crosslinking agent in the silane graft batch are preferably dry blended in advance and kneaded together in a kneader. The kneading time of the silane graft batch is preferably 0.01 to 10 minutes, more preferably 0.1 to 5 minutes.

  Each prepared batch is extruded into a pellet. Before molding, the silane graft batch, the flame retardant batch, and the catalyst batch are divided into three components, and the three components are kneaded for the first time in the molding process. That is, the polyolefin resin containing the silane graft polymer of the silane graft batch is kneaded with the moisture of the metal hydroxide of the flame retardant batch only after the final molding step.

  In order to knead the three components, a conventional kneader such as a Banbury mixer, a pressure kneader, a kneading extruder, a twin screw extruder, or a roll can be used. Prior to kneading, dry blending can also be performed with a normal tumbler or the like. The heating temperature at the time of kneading should just be the temperature which resin flows, and should just be in the range of the heating temperature implemented normally, for example, 100-250 degreeC. The kneading time is performed within a range of 0.1 to 2 minutes.

  The composition obtained by kneading the three components is extrusion coated on the outer periphery of the conductor using an extruder or the like immediately after kneading. And it is good to bridge | crosslink by exposing the coat | covered resin to water vapor | steam or water. At this time, it is preferable to carry out within a range of 48 hours within a temperature range of room temperature to 90 ° C. More preferably, the temperature is in the range of 60 to 80 ° C. and in the range of 12 to 24 hours.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

(Test material)
The manufacturer and the trade name of the test material used in this example are shown.

(A) Resin polyolefin resin [manufactured by Dow Chemical Japan Co., Ltd., trade name “engage 8100”]
Polypropylene elastomer [made by Nippon Polypro Co., Ltd., trade name “Newcom NAR6”]

(B) Flame retardant magnesium hydroxide [Kyowa Chemical Industry Co., Ltd., trade name “Kisuma 5”]

(C) hindered phenol antioxidant tetrakis- [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane [trade name, manufactured by Ciba Specialty Chemicals Co., Ltd. “Irganox 1010”]

(D) Semi-hindered phenol antioxidant 3,9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl]- 2,4,8,10-tetraoxaspiro [5.5] undecane [manufactured by Adeka Co., Ltd., trade name “Adeka Stub AO-80”]

(E) Bloom inhibitor zinc oxide (zinc flower) [product name "Zinc oxide" manufactured by Hakusuitec Co., Ltd.]
Zinc sulfide [made by Wako Pure Chemical Industries, Ltd., trade name "Zinc sulfide"]

(F) Cross-linking catalyst dibutyltin dilaurate [manufactured by Adeka Corporation, trade name “Mark BT-11”]

(G) Silane coupling agent vinyltrimethoxysilane [manufactured by Toray Dow Corning, trade name “SZ6300”]

(H) Crosslinker dicumyl peroxide (DCP) [Nippon Yushi Co., Ltd., trade name "Park Mill D"]

(Production of composition and insulated wire)
First, a component (silane graft batch), b component (flame retardant batch), and c component (catalyst batch) shown in Tables 1 and 2 to be described later are mixed.

  The a-component polyolefin resin, silane coupling agent and cross-linking agent were previously stirred and mixed at 50 rpm for 2 minutes, then each cylinder temperature was set to 180 to 200 ° C. using a twin screw extruder, and the silane was rotated at a screw rotation of 100 rpm. A graft batch was produced. In order to confirm whether or not this silane graft batch is sufficiently grafted, the obtained silane graft batch is subjected to water heating crosslinking in a high-humidity high-temperature bath at 90% humidity and 85 ° C., and the gel fraction is measured. did. All of the produced silane graft batches had a gel fraction of 60% or more, and it was confirmed that they were sufficiently grafted.

  Next, a component, b component, and c component are introduced into a kneading machine at a specified ratio and kneaded, and then formed into pellets with a pelletizer, and the composition according to this example and the composition according to the comparative example are prepared. Obtained. Then, each composition obtained was extrusion-coated at a thickness of 0.7 mm on the outer periphery of a conductor having an outer diameter of 2.4 mm, and subjected to water heating crosslinking in a high-humidity high-temperature tank having a humidity of 90% and a temperature of 85 ° C for 24 hours. Insulated wires according to this example and comparative example having an outer diameter of 3.8 mm were manufactured.

(Test method)
About the non-halogen-based insulated wire according to this example and the non-halogen-based insulated wire according to the comparative example produced as described above, the presence / absence of bloom, heat resistance, appearance of molded products, presence / absence of foaming, flexibility, and gasoline resistance were evaluated. did. Below, each evaluation method is demonstrated.

(With or without bloom)
The insulated wires according to the present example and the comparative example were left in a high-humidity high-temperature bath having a humidity of 95% and a temperature of 80 ° C. for 24 hours, and then the presence or absence of white powder on the surface of the insulated wires was visually confirmed. The one with white powder on the surface was regarded as having bloom.

(Heat-resistant)
The object having a diameter equal to the outer diameter of each electric wire was wound with the insulated electric wires according to this example and the comparative example 6 times, heated in a constant temperature bath at 180 ° C. for 120 to 360 hours, and then cooled to room temperature. As a result, those in which no cracks occurred in the insulator were accepted, and those in which cracks occurred were rejected.

(Appearance of molded product)
The surface of the insulated wire according to this example and the comparative example was confirmed visually and by hand, and the surface with a clean surface was marked with ◯, and the surface with roughness or irregularities was marked with ×.

(With or without foaming)
The determination of the presence or absence of foaming was performed by thinly slicing the surfaces of the insulated wires according to this example and the comparative example.

(Flexibility)
Judgment was made based on the hand feeling when the insulated wires according to the examples and comparative examples were bent by hand. That is, those with good tactile sensations were accepted and those with poor tactile sensations were rejected.

(Gasoline resistance)
The insulated wires according to this example and the comparative example were immersed in a liquid specified by ISO1817 at a temperature of 23 ± 5 ° C. for 20 hours. Thereafter, the insulated wire was taken out, wiped on the surface and dried at room temperature for 30 minutes, and then the outer diameter of the wire was measured within 5 minutes and wound around a prescribed mandrel. A value having an outer diameter change rate represented by the following formula within 15% was regarded as acceptable. Moreover, the presence or absence of the crack of an insulator was confirmed.
Rate of change in outer diameter = {(outer diameter before immersion−outer diameter after immersion) / outer diameter before immersion} × 100 (%)

  Tables 1 and 2 below show the composition of the composition and the evaluation results.

  Covering an insulator composed of a flame-retardant silane-crosslinked polyolefin resin composition formulated in combination with a hindered phenolic antioxidant, semi-hindered phenolic antioxidant, zinc oxide, and zinc sulfide, according to this example As shown in Table 1, the insulated wire thus obtained was confirmed to be resistant to blooming by the antioxidant and to have high heat resistance.

  On the other hand, as shown in Tables 1 and 2, the insulated wires according to Comparative Example 1 and Comparative Example 2 that did not contain a bloom inhibitor produced an antioxidant bloom and failed in heat resistance. It was.

  Moreover, although the insulated wire of Comparative Example 3 to Comparative Example 7 containing a bloom inhibitor does not produce bloom if either of the bloom inhibitors of zinc oxide or zinc sulfide is contained, either one of them In the case of the anti-blooming agent, or when both the anti-blooming agents contained only one of the anti-blooming agents, sufficient heat resistance could not be obtained.

  As described above, the flame-retardant silane-crosslinked polyolefin resin composition and the insulated wire according to the present embodiment and examples have been described, but the present invention is not limited to the above-described embodiments and examples, and the gist of the present invention. Various modifications are possible without departing from the scope.

Claims (5)

A polyolefin resin containing a silane graft polymer obtained by graft polymerization of an olefin resin with a silane coupling agent;
A hindered phenolic antioxidant and a semi-hindered phenolic antioxidant,
A bloom inhibitor comprising zinc oxide and zinc sulfide;
A flame retardant comprising a metal hydroxide;
Containing a crosslinking catalyst ,
The semi-hindered phenol antioxidant is 3,9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl]-. A flame-retardant silane-crosslinked polyolefin resin composition, which is 2,4,8,10-tetraoxaspiro [5.5] undecane .   The said hindered phenolic antioxidant is tetrakis- [methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane. The flame-retardant silane-crosslinked polyolefin resin composition described. The flame retardant silane according to claim 1 or 2 , wherein the flame retardant is selected from one or more of magnesium hydroxide, aluminum hydroxide, calcium hydroxide, zirconium hydroxide, and barium hydroxide. Cross-linked polyolefin resin composition. 0.5 to 10 parts by weight of the hindered phenol-based antioxidant, 0.5 to 10 parts by weight of the semi-hindered phenol-based antioxidant with respect to 100 parts by weight of the polyolefin-based resin containing the silane graft polymer, the zinc oxide from 0.5 to 10 parts by weight, the 0.5 to 10 parts by weight of zinc sulfide, one of claims 1 to 3, characterized in that it contains 50 to 200 parts by weight of the metal hydroxide 2. The flame-retardant silane-crosslinked polyolefin resin composition according to 1. An insulated wire comprising a cross-linked polyolefin resin obtained by kneading and heat-crosslinking the flame-retardant silane cross-linked polyolefin resin composition according to any one of claims 1 to 4 as an insulator.