JP2007063343A - Abrasion-resistant, flame-retardant resin composition and insulated wire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an abrasion-resistant, flame-retardant resin composition that is useful when used for electric wires for automobiles and the like. <P>SOLUTION: The abrasion-resistant, flame-retardant resin composition comprises 100 parts by mass of a base resin (mentioned below), 60-100 parts by mass of a silicone-treated metal hydroxide, 2-8 parts by mass of a flame retardant aid, 0.5-4.0 parts by mass of an antioxidant, and 0.25-2.0 parts by mass of a copper inhibitor, and it is crosslinked by electron beam irradiation. The base resin is obtained by mixing 60-95 parts by mass of a homopolypropylene (PP) having an elongation at break of ≥500% and a melt mass flow rate (MFR) of ≤0.5 g/10 min (230°C and 2.16 kg) and 5-40 parts by mass of a low density polyethylene having an elongation at break of ≥500% and an MFR of ≤0.25 g/10 min (190°C and 2.16 kg). By the above-mentioned, excellent characteristics, that is, excellent heat resistance, abrasion resistance, flame retardancy, moderate flexibility and the like are obtained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an abrasion-resistant flame retardant resin composition useful for, for example, an automobile electric wire and an insulated electric wire using the same.

In recent years, electric wires (including cables) for automobiles have been required to have characteristics such as heat resistance, wear resistance, and flame retardancy. Conventionally, in the case of an automobile electric wire mainly using a polyethylene (PE) resin composition, several types have been proposed because of its excellent properties such as cost and flame retardancy. However, electric wires using PE resin compositions are insufficient in terms of heat resistance and wear resistance, and in recent years, electric wires for automobiles using polypropylene (PP) resin compositions have begun to be used. Yes. For example, a coating material for an automobile electric wire using a composition (propylene-ethylene block copolymer) obtained by polymerizing a PP resin as a part of a resin component has been proposed (Cited document 1).
JP 2000-86858 A

  However, the required specifications for automobile wires in recent years are strict, and the above-mentioned required specifications cannot be sufficiently satisfied with the characteristics of the coating material for automobile wires using the above-described block copolymer. Furthermore, in addition to good heat resistance, wear resistance, flame retardancy, etc., the required specifications for automobile wires require moderate flexibility in handling during wiring. In particular, as will be described later, in the case of a resin composition containing a homo PP resin component, the rigidity is high and the flexibility tends to be easily lost.

Therefore, the present inventors have conducted various tests in search of a coating material for an automobile electric wire that has good heat resistance, wear resistance, flame retardancy, and the like and has appropriate flexibility.
As a result, base resin 100 mixed in the range of 60 to 95 parts by mass of homopolypropylene (homo PP) resin having specific characteristics and 5 to 40 parts by mass of low density polyethylene (LDPE) having specific characteristics. 60 to 100 parts by weight of a metal-treated metal hydroxide flame retardant, 2.0 to 8.0 parts by weight of a flame retardant aid, and 0.5 to 4.0 parts by weight of an antioxidant with respect to parts by weight. It was found that a wear-resistant flame retardant resin composition having desired characteristics can be obtained by crosslinking by electron beam irradiation. In particular , the addition of flame retardant aids reduces the amount of flame retardant added and suppresses the deterioration of mechanical properties. At the same time, it is used as a wire coating by the combined addition of antioxidants and copper damage inhibitors. In this case, it was found that discoloration and deterioration of the resin can be suppressed even at high temperatures, and as a result, improved heat resistance can be obtained. Of course, it has also been found that by coating this wear-resistant flame-retardant resin composition, an automobile electric wire satisfying the desired specifications can be obtained.

  The present invention was made from such a viewpoint. Basically, a predetermined amount of a flame retardant, a flame retardant aid, and an antioxidant are added to a base resin composed of a homo-PP resin and LDPE. By adding a copper damage inhibitor, an abrasion-resistant flame retardant resin composition having excellent characteristics is provided, and an insulated wire (including a cable) using the composition is also provided.

  The present invention according to claim 1 is characterized by 60 to 95 parts by mass of homopolypropylene (PP) having an elongation at break of 500% or more and a melt mass flow rate (MFR) of 0.5 g / 10 min (230 ° C., 2.16 Kg) or less. 100 parts by mass of base resin mixed in the range of 5 to 40 parts by mass of low density polyethylene having a point elongation of 500% or more and MFR of 0.25 g / 10 min (190 ° C., 2.16 Kg), and silicon-treated metal hydroxide 60 Comprising 100 parts by mass, 2-8 parts by mass of a flame retardant aid, 0.5-4.0 parts by mass of antioxidant, and 0.25-2.0 parts by mass of copper damage inhibitor, and an electron beam It exists in the abrasion-resistant flame-retardant resin composition characterized by making it bridge | crosslink by irradiation.

  The present invention according to claim 2 passes the flame retardancy by a 45 ° inclined combustion test at an elongation at break of 200% or more (tensile speed of 200 mm / min) by the electron beam irradiation, and wear resistance test The abrasion resistant flame retardant resin composition according to claim 1, wherein the number of scrapes is 150 times or more.

  The present invention according to claim 3 resides in the wear resistant flame retardant resin composition according to claim 1 or 2, wherein the metal hydroxide is magnesium hydroxide.

  The present invention according to claim 4 resides in the wear resistant flame retardant resin composition according to claim 1, 2 or 3, wherein the flame retardant aid is carbon black.

  The wear-resistant flame-retardant resin composition according to claim 1, wherein the crosslinking resin is added in an amount of 5 parts by mass or less to 100 parts by mass of the base resin. It is in the thing.

  The present invention according to claim 6 resides in an insulated wire that is coated with the composition according to claim 1, 2, 3, 4 or 5.

  According to the present invention, an excellent wear-resistant flame-retardant resin composition having appropriate heat resistance, abrasion resistance, flame retardancy, and the like and an appropriate flexibility can be obtained by the above-described configuration. Therefore, if this is used as a wire coating material, an excellent insulated wire, particularly an automotive wire can be obtained.

  The homopolypropylene (homo PP) resin used in the present invention is a resin having higher rigidity than random PP and block PP, and the properties of those specifically used include elongation at break of 500% or more (tensile speed of 200 mm). / Min), MFR 0.5 g / 10 min (230 ° C., 2.16 Kg) or less is preferable. Examples of such commercial products of homo PP resin include E111G (trade name) manufactured by Mitsui Chemicals.

  The low density polyethylene (LDPE) used in the present invention is a soft resin as compared with the high density polyethylene (HDPE), and the properties of what is specifically used include elongation at break of 500% or more (pulling speed 200 mm / min), The thing below MFR0.25g / 10min (190 degreeC, 2.16Kg) is preferable. As a commercial item of such a homo PP resin, for example, Ube Industries, UBEC150 (trade name) and the like can be mentioned.

  The purpose of the addition of LDPE is to improve the compatibility of the base resin with a flame retardant, that is, a metal hydroxide, in addition to the expected flexibility of the base resin.

  In this invention, LDPE is mixed in the range of 5-40 mass parts with respect to 60-95 mass parts of said homo PP type-resins, and 100 mass parts of base resins are obtained. The reason for this is that when the amount of LDPE added is less than 5 parts by mass, the desired softening effect cannot be obtained, and conversely, when it exceeds 40 parts by mass, the amount of homo PP resin relatively decreases, This is because good heat resistance and wear resistance due to the desired rigidity cannot be obtained.

  Examples of the flame retardant used in the present invention include metal hydroxides, and it is particularly preferable to use a metal-treated metal hydroxide. In the case of the silicone-treated one, the amount of the metal hydroxide added can be reduced in obtaining the desired flame retardant effect as compared with the case of no silicone treatment. For this reason, it is possible to suppress adverse effects caused by the large amount of addition, for example, deterioration of mechanical properties.

  In this invention, this flame retardant is 60-100 mass parts with respect to 100 mass parts of base resins. In general, when a silicone-untreated metal hydroxide is used as a flame retardant, it is necessary to add an amount exceeding 100 parts by mass with respect to 100 parts by mass of the base resin in order to obtain desired flame retardancy. Compared to this, it can be said that the addition amount is considerably small. As the reason, in addition to the silicone treatment effect, there is a synergistic effect due to the effect of adding a flame retardant aid described later. However, if it is less than 60 parts by mass, the desired flame retardancy cannot be obtained, and the lower limit addition amount is set to 60 parts by mass. On the other hand, as the amount added increases, the mechanical properties and the like of the resin composition decrease, so the upper limit was set to 100 parts by mass.

  Examples of the metal hydroxide of the flame retardant include magnesium hydroxide, aluminum hydroxide, calcium hydroxide, and the like, but it is preferable to use magnesium hydroxide, particularly magnesium hydroxide treated with silicone. As this commercial item, Kisuma 5P (trade name, manufactured by Kyowa Chemical Co., Ltd.) can be exemplified.

  In the present invention, carbon black is used as the flame retardant aid. In addition to becoming a colorant (black) of the resin composition, this addition is presumed to have effects such as formation of char (shell), reduction of diffusion of combustible gas, heat insulation and oxygen barrier. As described above, the addition effect of the flame retardant aid can provide an effect of reducing the addition amount (about 20%) with respect to the flame retardant addition of only the silicon-treated metal hydroxide (usually 80 to 120 parts by mass is required). Thus, the properties of the obtained resin composition, particularly, the reduction in tensile elongation at break can be minimized. As this flame retardant aid, it is possible to deal with ordinary commercial products such as Toka Black (trade name, manufactured by Tokai Black Co., Ltd.). And the addition amount is 2 to 8 parts by mass with respect to 100 parts by mass of the base resin. If the addition amount is less than 2 parts by mass, the addition effect is hardly obtained. This is because the wear resistance is lowered and may be below the standard value.

  In the present invention, in addition to the flame retardant aid, an antioxidant and a copper damage inhibitor are used in combination. The reason for this is that, as described above, by using this combined addition, when used as an electric wire coating, discoloration and deterioration of the resin can be suppressed even at high temperatures, and as a result, improved heat resistance can be obtained. It is. The addition amount of the antioxidant is 0.25 to 2.0 parts by mass with respect to 100 parts by mass of the base resin, and the addition amount of the copper damage inhibitor is 0.5 to 100 parts by mass with respect to 100 parts by mass of the base resin. The reason why 4.0 parts by mass is less than the respective lower limit value is that a desired effect cannot be obtained, and that the upper limit value is determined as described above, such as a problem of bloom or an increase in cost. This is because of this.

  Examples of commercially available antioxidants include Irganox 1010 (trade name, manufactured by Ciba Specialty Chemicals), which is a phenolic antioxidant. Moreover, as a commercial item of a copper damage prevention agent, CDA-1 (trade name, manufactured by Asahi Denka Kogyo Co., Ltd.), which is a triazole copper damage prevention agent, is exemplified.

  In the case of the resin composition of the present invention having such a composition, for example, when it is coated as an insulator of an insulated wire, it is crosslinked by electron beam irradiation. Although the electron beam irradiation may be performed in an atmospheric pressure, it is more preferable to perform the irradiation in a nitrogen atmosphere by taking an appropriate sealing means. And the irradiation intensity | strength is preferable to be about 0.5 Mrad, for example, when the coating thickness of an insulator is 0.2 mm. By the crosslinking by the electron beam irradiation, the composition properties can be improved. Moreover, when electron beam irradiation is performed in a nitrogen atmosphere, it becomes possible to prevent deterioration of the resin due to oxygen radicals (atmospheric oxygen and dissolved oxygen) generated by electron beam irradiation.

  In crosslinking by this electron beam irradiation, a crosslinking assistant is preferably added. Although it does not specifically limit as this crosslinking adjuvant, For example, use of a trimethylol propane trimethacrylate (TMPT) is desirable. At this time, a small amount of hydroquinone (HQ) may be used in combination. HQ has a function of suppressing the self-polymerization of TMPT by heat. Examples of commercially available TMPT include NK ester TMPT (trade name) manufactured by Shin-Nakamura Chemical Co., Ltd.

  And as addition amount of a crosslinking adjuvant, it is 5 mass parts or less with respect to 100 mass parts of base resins, Preferably it is 2-5 mass parts. If the amount is too small, the effect of promoting crosslinking cannot be obtained. Conversely, if the amount exceeds 5 parts by mass, bloom (seepage from the resin) becomes a problem. Moreover, the combined addition amount of HQ is not particularly limited, but is preferably about 25000 ppm with respect to TMPT.

  Moreover, in this invention, another additive can be suitably added with respect to the said composition as needed. For example, hydrogenated rubber materials and pigments for whitening prevention.

<Examples and comparative examples>
By the abrasion-resistant flame-retardant resin composition of the present invention (Examples 1 to 10) and the resin composition lacking the conditions of the present invention (Comparative Examples 1 to 11) consisting of the formulations shown in Tables 1 and 2. A sample insulated wire was manufactured. The sample insulated wire was formed by subjecting the above composition to extrusion coating (coating outer diameter φ1.3 mm) as an insulator having a thickness of 0.2 mm on a conductor having an outer diameter φ0.9 mm, and an electron beam in a nitrogen atmosphere. Irradiation was performed. The intensity of electron beam irradiation was 0.5 Mrad. Moreover, the numerical value of the compounding material in a table | surface shows a mass part. The homo PP resin used is E111G (trade name) manufactured by Mitsui Chemicals, LDPE is UBEC 150 (trade name) manufactured by Ube Industries, and the flame retardant is magnesium hydroxide of a metal-treated metal hydroxide. Kisuma 5P (trade name, manufactured by Kyowa Chemical Co., Ltd.), flame retardant aid is Toka Black (trade name, manufactured by Tokai Black), and antioxidant is Irganox 1010 (trade name, manufactured by Ciba Specialty Chemicals) The copper damage inhibitor is CDA-1 (trade name, manufactured by Asahi Denka Kogyo Co., Ltd.), and the crosslinking assistant is TMPT combined with 25000 ppm of HQ, NK ester TMPT (trade name, manufactured by Shin-Nakamura Chemical Co., Ltd.). is there.

  With respect to the insulated wires of each sample thus obtained, the following physical property evaluations were made, that is, “abrasion resistance”, “elongation at break”, “flame resistance”, “stain of crosslinking aid” Existence of presence / absence ”,“ presence / absence of discoloration / degradation of resin due to copper tape ”, and“ presence / absence of bloom of antioxidant ”were also shown in Tables 1 and 2.

  “Abrasion resistance”, which was performed according to the blade reciprocation method of the abrasion resistance test of ISO6722. Here, the needle diameter is φ0.45 mm and the load is 720 g. Then, a repeated test was conducted, and the number of scrapes until the coating was peeled off and conduction with the conductor was 150 or more passed, and less than 150 was rejected.

  “Elongation at break”, which was determined by the tensile test (based on the tensile test of JIS-C3005) as the tensile rate of 200 mm / min and the elongation at break of the insulator and the sheath. Then, the case where the elongation at break was 200% or more was accepted and indicated by “◯”, the case where the elongation at break was less than 200% was rejected and indicated by “x”.

  “Flame retardance”, which was performed in accordance with ISO 6722 45 ° inclined combustion test. The test was performed 5 times for all the samples, and the number at the time of autolysis within 70 seconds was expressed in molecules. And it was set as pass (5/5) when it self-digested within 70 seconds by all five, and it was set as unacceptable (1/5-4/5) at other times.

  “Presence or absence of bleeding of crosslinking aid”, which was observed visually for each sample. And when all 5 out of 5 ooze out and there was no abnormality, it was set as the pass (5/5), and when it was other than that, it was set as the rejection (1/5-4/5).

  “Presence / absence of discoloration / deterioration of resin conductor by copper tape”, in which each sample was brought into contact with the copper tape, put in a constant temperature bath (140 ° C.) in this state, and left for 625 hours. And the contact part of the flame retardant resin composition coating and the conductor was visually observed. Then, all five out of the five samples were judged as acceptable when no discoloration or deterioration occurred, indicated by “◯”, and when any one of them was discolored or deteriorated, rejected, and indicated by “x”.

  “Presence / absence of bloom of antioxidant”, which was obtained by visually observing each sample. And when all 5 out of 5 ooze out and there was no abnormality, it was set as the pass (5/5), and when it was other than that, it was set as the rejection (1 / 5-4 / 5).

  From Table 1 above, in the insulated wires (Examples 1 to 10) using the wear-resistant flame retardant resin composition according to the present invention, all characteristics, that is, wear resistance, elongation at break, It can be seen that good results have been obtained with respect to flame retardancy, presence or absence of the crosslinking aid, presence or absence of discoloration or deterioration of the resin due to the copper tape, and presence or absence of the antioxidant bloom.

On the other hand, it can be seen from Table 2 that there is a problem in any of the characteristics of the insulated wires lacking the requirements of the present invention (Comparative Examples 1 to 11). In addition, when Comparative Example 1 has no LDPE addition, Comparative Example 2 has a large amount of LDPE added (50 parts by mass), Comparative Example 3 has a small amount of metal hydroxide added (40 parts by mass), Comparative Example 4 has a large amount of added metal hydroxide (120 parts by mass), Comparative Example 5 has a small amount of flame retardant aid (1 part by mass), and Comparative Example 6 has a large amount of flame retardant aid ( 10 parts by mass), Comparative Example 7 has a large amount of TMPT as a crosslinking aid (7 parts by mass), Comparative Example 8 has a small amount of antioxidant (0.3 parts by mass), and Comparative Example 8 has a large amount of antioxidant. In the case (6 parts by mass), Comparative Example 10 is when the copper damage inhibitor is low (0.1 parts by mass), and Comparative Example 11 is when the copper damage inhibitor is high (3 parts by mass).

Claims (6)

Elongation at break 500% or more, melt mass flow rate (MFR) 0.5 g / 10 min (230 ° C., 2.16 Kg) or less homopolypropylene (PP) 60-95 parts by mass, elongation at break 500% or more, MFR 0.25 g / 10 min (190 ° C., 2.16 Kg) or less of low density polyethylene 5 to 40 parts by mass of base resin, silicon treated metal hydroxide 60 to 100 parts by mass, flame retardant aid It consists of 2 to 8 parts by weight of an agent, 0.5 to 4.0 parts by weight of an antioxidant, and 0.25 to 2.0 parts by weight of a copper damage inhibitor, and is crosslinked by electron beam irradiation. Abrasion resistant flame retardant resin composition. By the electron beam irradiation, the elongation at break is 200% or more (tensile speed is 200 mm / min), the flame retardancy by the 45 ° inclined combustion test is passed, and the number of scrapes of the abrasion resistance test is 150 times or more. The wear-resistant flame-retardant resin composition according to claim 1. The wear-resistant flame retardant resin composition according to claim 1 or 2, wherein the metal hydroxide is magnesium hydroxide. The wear resistant flame retardant resin composition according to claim 1, 2 or 3, wherein the flame retardant aid is carbon black. The wear-resistant flame-retardant resin composition according to claim 1, 2, 3, or 4, wherein 5 parts by mass or less of a crosslinking aid is added to 100 parts by mass of the base resin. An insulated wire, wherein the composition according to claim 1, 2, 3, 4 or 5 is coated.