JP2007056204A - Flame-retardant resin composition and insulated electric wire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a halogen-free flame-retardant resin composition such as to be used for covering electric wires. <P>SOLUTION: The flame-retardant resin composition is obtained by incorporating 100 pts.mass of a base resin as a blend of 80-95 pts.mass of a polypropylene-based resin and 5-20 pts.mass of polyethylene with 70-110 pts.mass of a metal hydroxide such as magnesium hydroxide. Owing to incorporating polyethylene in the polypropylene-based resin, this flame-retardant resin can be afforded with more excellent properties, i.e. abrasion resistance, flame retardancy, heat resistance, moderate flexibility, etc. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a non-halogen flame retardant resin composition, which is used, for example, for coating electric wires or resin sheets, and particularly useful for coating wire harnesses for automobiles. It relates to an insulated wire.

In recent years, flame retardant resin compositions using polyolefin resins have been proposed as various resin compositions for electric wire coating. In particular, vinyl chloride resin that has both wear resistance and flexibility has been used as a covering material for wire harnesses for automobiles. However, this resin contains a halogen element, and dioxins are not generated when burned. It is known to occur.
Therefore, in recent years, materials mainly composed of polyolefin resins not containing halogen elements have been studied. However, since it is difficult to ensure abrasion resistance with flexible polyolefin-based resins, flame retardant resin compositions mainly composed of polypropylene having excellent abrasion resistance have been proposed (Cited documents 1-2). Such).
Japanese Patent Laid-Open No. 10-294021 JP 11-118529 A

However, since polypropylene (PP) resins are hard and have problems with low-temperature characteristics, various studies have been made to solve these problems by mixing with resins that are flexible and have excellent low-temperature characteristics. Alternatively, it has also been proposed to solve problems such as hardness as a copolymer obtained by random polymerization or block polymerization of ethylene to a PP resin (Cited document 3).
JP 2000-86858 A

  However, in recent years, the required specifications for electric wires for automobiles have become stricter, and it has been difficult to achieve both a reduction in wear resistance and flame retardancy even by the above-described methods.

That is, when making a PP resin flame retardant, if a metal hydroxide such as magnesium hydroxide is added as a flame retardant, a decrease in wear resistance is inevitable. However, if the amount of the flame retardant added is reduced, sufficient flame retardance cannot be secured this time.
In addition to the wear resistance and flame resistance, the required specifications for automobile wires require good heat resistance and appropriate flexibility in handling during wiring, and these conditions are also met. There is a need.

Therefore, the present inventor conducted various tests in search of a flame retardant resin composition having good heat resistance and moderate flexibility, in particular, a coating material for automobile electric wires, as well as abrasion resistance and flame resistance. went.
As a result, 70 to 110 parts by mass of metal hydroxide was added to 100 parts by mass of base resin mixed in the range of 80 to 95 parts by mass of polypropylene resin and 5 to 20 parts by mass of polyethylene. It has been found that a flame retardant resin composition that satisfies the requirements can be obtained.

  The present invention has been made from such a viewpoint, and basically has excellent characteristics by adding a predetermined amount of metal hydroxide to a base resin composed of PP resin and polyethylene. The flame retardant resin composition is provided, and insulated wires (including cables) and various resin molded products using the same are also provided.

  The present invention according to claim 1 adds 70 to 110 parts by mass of a metal hydroxide to 100 parts by mass of a base resin mixed in a range of 80 to 95 parts by mass of a polypropylene resin and 5 to 20 parts by mass of polyethylene. It exists in the flame-retardant resin composition characterized by becoming.

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

  In the third aspect of the present invention, the metal hydroxide is treated with any one of stearic acid, a silane coupling agent, and a titanate coupling agent, and the content of the treating agent is 0.5% by mass. It exists in the flame-retardant resin composition of Claim 1 or 2 characterized by the following.

  The present invention according to claim 4 is characterized in that, of 80 to 95 parts by mass of the polypropylene resin, 5 to 20 parts by mass is a propylene-α-olefin copolymer having a surface hardness (ASTM-D2240) of 60 or less. It exists in the flame-retardant resin composition of Claim 1, 2 or 3.

  The present invention according to claim 5 is the hydrogenated styrene / ethylene / butylene / styrene copolymer or ethylene / ethylene copolymer in 5 to 10 parts by mass of 5 to 20 parts by mass of the propylene-α-olefin copolymer of claim 4. The flame retardant resin composition is characterized in that it is an α-olefin copolymer.

  The present invention described in claim 6 resides in the flame retardant resin composition according to claims 1, 2, 3, 4 or 5, wherein the polypropylene resin has a melting point of 160 ° C or higher.

  The present invention according to claim 7 is the flame retardant resin composition according to claim 1, 2, 3, 4, or 6, wherein the polyethylene is low density polyethylene or linear low density polyethylene. It is in.

  The present invention according to claim 8 is the flame retardant resin composition according to claim 1, 2, 3, 4, 5, 6 or 7, wherein the composition is crosslinked by electron beam irradiation. .

  The present invention according to claim 9 is an insulated wire characterized in that the flame retardant resin composition according to any one of claims 1 to 8 is coated on a conductor.

  According to the present invention, an excellent flame retardant resin composition having good heat resistance and appropriate flexibility as well as abrasion resistance and flame retardancy can be obtained by the above-described configuration. Therefore, the use is not particularly limited, but if this is used as a wire coating material, an excellent insulated wire, particularly an automotive wire can be obtained.

  The polypropylene (PP) resin used in the present invention includes random PP and block PP in addition to homo PP. Random PP and block PP are copolymers obtained by random polymerization or block polymerization of polyethylene on polypropylene. These may be used alone or in combination as a mixture. In addition, the melting point of these PP resins is preferably 160 ° C. or higher. It is because favorable heat resistance is obtained because melting | fusing point is 160 degreeC or more. That is, it is because the resin composition of the level which passes the heat resistant grade of 85 degreeC and 100 degreeC by ISO6722 standard is obtained.

  The PP resin is mixed in the range of 5 to 20 parts by mass of polyethylene with respect to 80 to 95 parts by mass to obtain 100 parts by mass of the base resin. This is because, by mixing this polyethylene, even if an appropriate amount of a metal hydroxide as a flame retardant is added (an amount capable of maintaining a desired flame retardancy), a decrease in wear resistance can be suppressed. In other words, since the metal hydroxide is selectively dispersed in the polyethylene due to the presence of the polyethylene, it is presumed that the original characteristics of the PP-based resin component part are maintained, and a decrease in wear resistance can be suppressed. The Since polyethylene is softer than PP resin, moderate flexibility can be secured.

  In securing this flexibility, more specific characteristics of the PP-based resin include the use of those having an elongation at break of 500% or more (tensile speed 200 mm / min) and MFR 1.0 g / 10 min (230 ° C., 2.16 Kg) or less. Is preferred. Examples of such commercially available PP resin include E111G (trade name, homo PP, melting point 165 ° C., MFR = 0.5 g / 10 min), B221W (trade name, random PP, melting point 148, manufactured by Prime Polymer Co., Ltd. ° C, MFR = 0.5 g / 10 min), EG8 (trade name, block PP, melting point 161 ° C., MFR = 0.5 g / 10 min), B701WB (trade name, block PP, melting point 163 ° C., MFR = 0.5 g / min) 10 min)).

  Moreover, although it does not specifically limit as said polyethylene (A polyethylene-type resin is also possible), Low density polyethylene (LDPE) and linear low density polyethylene (LLDPE) rather than high density polyethylene (HDPE) and medium density polyethylene (MDPE). Use is preferred. These may be used alone or in combination as a mixture. By adding this polyethylene, as described above, a decrease in the wear resistance of the resin composition can be suppressed. In addition, moderate flexibility can be secured. For this reason, with respect to 80-95 mass parts of PP-type resin, the addition amount of polyethylene needs to mix in the range of 5 mass parts or more and 20 mass parts or less to make 100 mass parts of base resin. That is, when the amount of polyethylene added is less than 5 parts by mass, a decrease in wear resistance of a desired resin composition cannot be suppressed, and appropriate flexibility cannot be ensured. However, when the added amount of polyethylene exceeds 20 parts by mass, the polymer becomes too soft and problems such as loss of the characteristics of the main component PP resin occur.

  In securing such properties, more specific properties of polyethylene include the use of an elongation at break of 500% or more (tensile speed 200 mm / min) and MFR 1.0 g / 10 min (190 ° C., 2.16 Kg) or less. preferable. Examples of such a commercially available polyethylene include UBEC150 (trade name, LDPE) manufactured by Ube Industries, Ltd., and the like.

  Examples of the metal hydroxide to be added in an amount of 70 to 110 parts by mass to 100 parts by mass of the base resin thus formed include magnesium hydroxide, aluminum hydroxide, calcium hydroxide and the like. Preferably, magnesium hydroxide is used. Is desirable. Furthermore, in order to obtain a desired flame retardancy, it is more desirable to use a surface-treated metal hydroxide so that a smaller addition amount is sufficient. Examples of the surface treatment agent include stearic acid, a silane coupling agent, a titanate coupling agent, and the like. However, when the amount of the surface treatment agent is increased, there is a problem of a decrease in wear resistance. Therefore, the content of the treatment agent is preferably 0.5% by mass or less. As this commercial item, for example, Kisuma 5LA (trade name, manufactured by Kyowa Chemical Co., Ltd., stearic acid surface treatment, treatment amount 0.5% by mass or less), Kisuma 5 (trade name, manufactured by Kyowa Chemical Co., Ltd., without surface treatment) ) And the like.

  The addition amount of the metal hydroxide is set to 70 to 110 parts by mass. If the amount is less than 70 parts by mass, the desired flame retardancy cannot be obtained. This is because a decrease in wear is inevitable. Here, the desired flame retardancy is a level that passes the flame retardancy by the 45 ° inclined combustion test.

  In the resin composition formed in this way, in order to ensure better flexibility depending on the use, 5 to 20 masses of the PP resin component (80 to 95 parts by mass) of the base resin as necessary. Part can be replaced as a propylene-α-olefin copolymer having a surface hardness (ASTM-D2240) of 60 or less. The propylene-α-olefin copolymer having a surface hardness of 60 or less is softer than the PP resin component, so that flexibility can be secured. On the other hand, with the addition amount in this range, the wear resistance is slightly lowered, but flame retardancy is achieved. There is no effect on sex. Examples of commercially available products include Tuffmer XM-7070 (trade name) manufactured by Mitsui Chemicals.

  Furthermore, in this resin composition, in order to obtain higher cold resistance, among the propylene-α-olefin copolymers having a surface hardness of 5 to 20 parts by mass (ASTM-D2240) of 60 or less, if necessary, 5 to 10 parts by mass can be replaced as hydrogenated styrene / ethylene / butylene / styrene copolymer (HSBR) or ethylene-α-olefin copolymer. These resin materials have better flexibility and low-temperature characteristics than propylene-α-olefin copolymer components having a surface hardness of 60 or less, so that the cold resistance can be improved. There is almost no influence. As this commercial product of HSBR, for example, manufactured by Japan Synthetic Rubber (JSR), Dye Nylon 1321P (trade name), and as a commercial product of ethylene-α olefin copolymer, for example, manufactured by Mitsui Chemicals, And Tuffmer A-055OS (trade name).

  The resin composition of the present invention having such a composition contains a crosslinking agent, a crosslinking aid, an antioxidant, an ultraviolet degradation inhibitor, a processing aid, a color pigment, carbon black, etc., if necessary depending on the intended use. It can be added as appropriate.

  In order to coat this resin composition of the present invention as, for example, an insulator of an insulated wire, it may be simply extrusion-coated, but can also be 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 and comparative examples>
The flame-retardant resin composition of the present invention (Examples 1 to 22) having the composition shown in Tables 1 to 4 and the resin composition lacking the conditions of the present invention (Comparative Examples 1 to 16) An insulated wire was manufactured. In addition, the insulated wire of a sample uses the conductor (19 / 0.12), the coating layer of thickness 0.25mm was formed by extrusion with the flame retardant resin composition of each of the above examples, and the outer diameter was 1. 04 mm. After extrusion, electron beam irradiation was performed in a nitrogen atmosphere. 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 PP resin used is Prime Polymer, E111G (trade name, homo PP, melting point 165 ° C.), polyethylene is UBE 150 (trade name, LDPE) manufactured by Ube Industries, and metal hydroxide magnesium hydroxide is Kisuma 5A (trade name, manufactured by Kyowa Chemical Co., Ltd., stearic acid surface treatment, treatment amount 1% by mass or more), Kisuma 5LA (trade name, produced by Kyowa Chemical Co., Ltd., stearic acid surface treatment, treatment amount 0.5% by mass or less), Kisuma 5 (trade name, manufactured by Kyowa Chemical Co., Ltd., without surface treatment), propylene-α-olefin copolymer has a surface hardness of 60 or less, manufactured by Mitsui Chemicals, Tuffmer XM-7070 (trade name), ethylene -Α-olefin copolymer is manufactured by Mitsui Chemicals, Tuffmer A-055OS (trade name), HSBR (hydrogenated styrene / ethylene / butylene / styrene copolymer) Is a die nylon 1321P (trade name) manufactured by JSR Corporation.

  For the insulated wires of each sample thus obtained, the following physical property evaluation, that is, "tensile breaking strength", "tensile breaking elongation", "flame retardant", "wear resistance", The “cold resistance” test was performed, and the results are shown in Tables 1 to 4 together.

  “Tensile rupture strength”, a conductor is pulled out from a sample insulated wire having a length of about 150 mm, and marked lines are arranged at intervals of 20 mm in the central part of the cylindrical insulator, and are attached to the chuck of the test apparatus specified in JISB7721. The tensile breaking strength was determined from the breaking tensile load of the sample at a mounting and pulling speed of 200 mm / min. And the case where tensile fracture strength was 10 Mpa or more was made "pass", and the case where it was less than this was made "fail".

  “Tensile rupture elongation”, a conductor is removed from a sample insulated wire having a length of about 150 mm, and marked lines are arranged at intervals of 20 mm in the center of the cylindrical insulator, and are attached to the chuck of the test apparatus specified in JIS B7721. The tensile elongation at break was determined from the length between the marked broken lines of the insulated wire of the sample at a mounting and pulling speed of 200 mm / min. A case where the tensile elongation at break was 150% or more was determined as “pass”, and a case where the tensile break elongation was less than this was determined as “fail”.

  “Flame retardance”, which was performed in accordance with ISO 6722 45 ° inclined combustion test. The test was performed on insulated wires (length: 500 mm) of all the samples, self-digested within 70 seconds, and the one with the upper 50 mm remaining in 500 mm was regarded as “pass”, and the one with only the upper 50 mm remaining was “not acceptable”. Passed ".

  “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 7N. The test was repeated, and the number of scrapes until the coating was peeled off and conduction with the conductor was displayed. Here, the number of scrapes of 100 or more is a “pass” level, and less than that is a “fail” level.

  "Cold resistance", which was performed by the embrittlement test of ASTM-D1790. A case where the embrittlement temperature is −20 ° C. or lower is “A”, a case where the embrittlement temperature is more than −20 to less than −10 ° C. is “B”, and a case where the embrittlement temperature is −10 or more is “C”. "

  From Tables 1 and 2 above, in the insulated wires (Examples 1 to 12) using the flame-retardant resin composition according to the present invention, all the characteristics, that is, “tensile rupture strength”, “tensile rupture” It can be seen that good results have been obtained for “elongation”, “flame retardant”, “abrasion resistance”, and “cold resistance”.

  On the other hand, it can be seen from Tables 3 to 4 that the insulated wires lacking the requirements of the present invention (Comparative Examples 1 to 13) have problems in any of the characteristics. In Comparative Examples 1 to 4, when the blending amount of the PP resin and polyethylene is outside the requirement range of the present invention, Comparative Examples 5 to 8 are compared when the blending amount of the metal hydroxide is outside the requirement range of the present invention. In Examples 9 to 10, when the content of the metal hydroxide treatment agent is outside the requirement range of the present invention, in Comparative Example 11, the blending amount of the PP resin and the propylene-α-olefin copolymer is outside the requirement range of the present invention. In Comparative Example 12, when the blending amounts of the PP resin, propylene-α olefin copolymer and ethylene-α olefin copolymer are outside the requirements of the present invention, Comparative Example 13 is a PP resin, propylene-α. This is a case where the blending amounts of the olefin copolymer and HSBR are outside the requirement range of the present invention.

In the above description, the flame retardant resin composition according to the present invention is used for covering an electric wire, and an insulated wire using the same is described. However, the flame retardant resin composition of the present invention is applied to this. It is not limited, It can use also for various things, such as other resin molded products, for example, a resin sheet.

Claims (9)

Flame retardancy characterized by adding 70 to 110 parts by mass of metal hydroxide to 100 parts by mass of base resin mixed in the range of 80 to 95 parts by mass of polypropylene resin and 5 to 20 parts by mass of polyethylene. Resin composition. The flame retardant resin composition according to claim 1, wherein the metal hydroxide is magnesium hydroxide. The metal hydroxide is treated with any of stearic acid, a silane coupling agent, and a titanate coupling agent, and the content of the treatment agent is 0.5% by mass or less. Item 3. A flame retardant resin composition according to item 1 or 2. 4. The propylene-α olefin copolymer having a surface hardness (ASTM-D2240) of 60 or less is used as 80 to 95 parts by mass of the polypropylene-based resin. Flame retardant resin composition. Of the 5 to 20 parts by mass of the propylene-α-olefin copolymer according to claim 4, 5 to 10 parts by mass are hydrogenated styrene / ethylene / butylene / styrene copolymer or ethylene / α-olefin copolymer. A flame-retardant resin composition. The flame retardant resin composition according to claim 1, 2, 3, 4, or 5, wherein the polypropylene resin has a melting point of 160 ° C or higher. The flame-retardant resin composition according to claim 1, 2, 3, 4, or 6, wherein the polyethylene is low-density polyethylene or linear low-density polyethylene. The flame retardant resin composition according to claim 1, wherein the composition is crosslinked by electron beam irradiation. An insulated wire comprising a conductor coated with the flame retardant resin composition according to claim 1.