JP2010235800A - Heat-resistant protector for automobile cable and cable for automobile - Google Patents

Abstract

[PROBLEMS] To provide a heat-resistant protector that can be obtained by simple raw materials and processes, has high heat resistance and rubber elasticity, and can withstand long-term use, and can be heat-welded because the obtained material is thermoplastic. I will provide a.
A heat-resistant protector for an automobile cable obtained by extruding into a tube a material obtained by adding 5 to 30 parts of polymethylpentene to 100 parts by weight of an olefin-based thermoplastic elastomer. The olefinic thermoplastic elastomer is preferably one in which a crosslinked ethylene-propylene copolymer rubber is dispersed in a polypropylene resin. In addition, an automobile cable in which an outer layer of a polypropylene-based outer resin is coated with the above heat-resistant protector and then thermally welded.
[Selection] Figure 1

Description

  The present invention relates to a control cable for performing remote operation in an automobile, and more particularly to a heat-resistant protector used for protecting a control cable.

  In order to remotely control an automobile accelerator, clutch, transmission, brake, and the like from a driver's cab, a control cable in which a metal wire is coated with a resin is known. Such a control cable is disposed at the bottom of the vehicle body (this is called routing), and a target device is connected to a lever or pedal that is directly operated by the driver in the driver's cab.

  Since the control cable is routed at the bottom of the vehicle body, it is necessary to protect it from stepping stones from the road surface when traveling, and high temperatures in the vicinity of high-temperature areas such as the engine room, silencer, and exhaust pipe. Need to be protected from. Therefore, a heat-resistant protector for protecting the cable is coated on the control cable for the purpose of protection from physical destruction and protection from destruction due to thermal degradation. Such heat-resistant protectors for protecting cables are generally required to have operability durability at 170 ° C. atmosphere. This is a required performance because the automobile cable material passing near the high temperature region may be exposed to the temperature.

  Conventionally, so-called ethylene propylene diene monomer rubber (hereinafter sometimes abbreviated as EPDM rubber) obtained by vulcanizing an ethylene-propylene copolymer has been used for such a heat-resistant protector that requires heat resistance.

  However, since this material requires vulcanization in the production process, complicated raw material blending and kneading processes and a long vulcanization process are necessary during the manufacture of the protector, which causes high costs. Further, such a rubber vulcanized product has a drawback that the vulcanized material remains in the product, and when it is exposed to a high temperature for a long time, the strength / elongation is lowered and becomes hard and brittle. Furthermore, since EPDM rubber is a thermosetting rubber, it cannot be thermally welded to the polypropylene-based outer coat material (thermoplastic) used in the cable material, and must be fixed using an adhesive. It was.

  On the other hand, in order to solve these problems, proposals have been made to use a thermoplastic elastomer as a protector. For example, 10 to 40 parts of a silane-modified polypropylene resin is added to 100 parts of a dynamically crosslinked olefin-based thermoplastic elastomer. Thus, a material having an A hardness of 95 or less that has been subjected to water vapor crosslinking has been proposed (see, for example, Patent Document 1).

  However, this material needs to be subjected to water vapor treatment for a considerably long time (about 8 hours) after molding in order to use the silane-modified resin to exhibit its water vapor crosslinkability. Furthermore, since heat sealability is essentially lost due to the thermosetting resin, there is a problem that a fixing method using an adhesive must be taken.

JP-A-9-143277

  The present invention has been made in view of the above circumstances, and is a heat-resistant protector that is obtained without using complicated raw materials and processes such as EPDM rubber, has high heat resistance and rubber elasticity, and can withstand long-term use. In addition, an object of the present invention is to provide a heat-resistant protector that can be thermally welded because the material obtained is thermoplastic.

  The heat-resistant protector for automobile cables according to the present invention is characterized in that 5 to 30 parts of polymethylpentene is added to 100 parts by weight of an olefin-based thermoplastic elastomer and extruded into a tube shape.

  In the present invention, it is preferable that the olefin-based thermoplastic elastomer is obtained by dispersing a cross-linked ethylene-propylene copolymer rubber in a polypropylene resin.

  Further, the automobile cable of the present invention is characterized in that the outer coat resin of the automobile cable is a polypropylene type, and its outer layer is coated with the heat resistant protector and then thermally welded.

  According to the present invention, since polymethylpentene is added to the olefinic thermoplastic elastomer, it is possible to provide a heat-resistant protector that has both heat resistance and flexibility and can withstand long-term use. In addition, the manufacturing process does not require vulcanization and is a dry blend of thermoplastic olefin (hereinafter sometimes abbreviated as TPO) and polymethylpentene, which can be molded by ordinary extrusion molding, so it is extremely workable. Is good. Furthermore, since it is a thermoplastic material, it can be heat-welded by being in close contact with the outer coat to be coated and heated, thereby providing a good working environment that does not use an adhesive and having good working efficiency. Play.

It is a partial perspective view of the cable for motor vehicles of the present invention, and a heat-resistant protector. It is a schematic diagram which shows the example of wiring of the cable for motor vehicles and heat-resistant protector of this invention in an Example. It is a schematic diagram which shows the ultrasonic welding for welding the heat-resistant protector of this invention to an outercoat.

Hereinafter, the present invention will be described in detail.
FIG. 1 is a partial perspective view showing an example of an automobile control cable C targeted by the present invention. The control cable C has an inner wire 1 made of a metal stranded wire or the like for connecting an operating means such as a lever or a pedal (not shown) for remote operation and devices such as an accelerator, a clutch, a transmission, and a brake. The outer side of the wire 1 is covered with an inner coat 2, an outer lower winding 3, an outer coat 4, and a protector 5 in this order. Since the boundary surface between the inner coat 2 and the outer lower winding 3 is not bonded and is slidable, the inner coat 1 and the outer lower winding 3 are pulled by pulling (or pushing) the inner wire 1 by operating the operating means. Can slide and remotely control the device.

  In the present invention, the protector 5 is characterized by being extruded in a tube shape by adding 5 to 30 parts of polymethylpentene to 100 parts by weight of an olefin-based thermoplastic elastomer. The inner wire 1, the inner coat 2, the outer lower winding 3 and the outer coat 4 are not limited, and a known technique can be adopted.

  In the present invention, as the olefinic thermoplastic elastomer, in particular, an ethylene-propylene copolymer rubber is dynamically cross-linked in polypropylene, and the cross-linked ethylene-propylene copolymer rubber is dispersed in a polypropylene resin. Is preferred. This olefinic thermoplastic elastomer is so-called TPO, which is a radically decomposable polypropylene, a radically crosslinkable ethylene-propylene random copolymer rubber (EPDM), and other process oils as necessary. Further, the copolymer rubber is dispersed while being crosslinked while heating and kneading in the presence of an organic peroxide such as an antioxidant and a crosslinking aid.

  Here, the ethylene-propylene copolymer rubber is an amorphous elastic body, and ethylene and propylene are preferably in a molar ratio of 50/50 to 85/15. In order to further improve the crosslinkability, the nonconjugated diene has an iodine value. Is copolymerized at a ratio of 50 or less. Examples of non-conjugated dienes include 1,4-hexadiene, dicyclopentadiene, and ethylidene norbornene. Examples of the polypropylene used here include propylene homopolymers and polymers in which propylene and α-olefin are copolymerized at a ratio of 10 mol% or less. Examples of such α-olefins include ethylene, butylene, hexene, octene and the like. The ratio of polypropylene to ethylene-propylene copolymer rubber is preferably 10/90 to 70/30 by weight.

  In this TPO, polypropylene has a continuous phase and crosslinked EPDM rubber has a disperse phase. Therefore, the TPO has a certain strength up to the vicinity of the melting point of the polypropylene. Disappear.

  Examples of the type of TPO include Miralastomer manufactured by Mitsui Chemicals, Thermorun manufactured by Mitsubishi Chemical, Exellink manufactured by JSR, and Santoprene manufactured by AES.

  The polymethylpentene used in the present invention is a high melting point resin having a melting point of 220 to 240 ° C. and is a methyl-1-pentene polymer, such as 4-methyl-1-pentene, 3-methyl-1-pentene. Homopolymers of these or copolymers thereof, copolymers of 4-methyl-1-pentene and / or 3-methyl-1-pentene with other α-olefins are preferred. Examples of the α-olefin include α-olefins having 2 to 20 carbon atoms such as ethylene, propylene, 1-butene, 1-octene, and 1-decene.

  Polymethylpentene is sold as a commercial product under the trademark TPX manufactured by Mitsui Chemicals. The preferred number of parts by weight of polymethylpentene with respect to 100 parts by weight of TPO is 5 to 30 parts by weight. When the added part of polymethylpentene is less than 5 parts by weight, the heat resistance is lowered and the 170 ° C. operation durability test described later is not passed. As the number of added parts increases, the hardness increases from rubber to plastic, and when it exceeds 30 parts by weight, the cable becomes difficult to bend freely and the assembly to the car deteriorates, and further, the vibration makes contact with the car body. The sound of time is generated. The most preferable addition amount is 5 to 20 parts by weight. In the range of this addition amount, the A hardness is stable at a low value, and the cableability is very good.

  Mixing of TPO and polymethylpentene can be performed by so-called dry blending. Therefore, kneading can be carried out without any problem by simply putting the mixed pellets into the extruder and extruding it by a conventional method.

  About the heat welding of the polypropylene outer material of the automobile control cable and the heat-resistant protector of the present invention, it is possible to use a known welding means such as a heat welder, an ultrasonic welder or a high frequency welder. In the present invention, the outer coat material and the heat-resistant protector are of the same system and are thermoplastic, so the heat weldability is good.

  Of these means, an ultrasonic welder is shown in FIG. As shown in FIG. 3, the heat-resistant protector 5 of the present invention is coated on the outer coat 4 of the control cable C for automobiles, and the ultrasonic welding oscillation jig 8 is brought into contact with the welded portion 9 on the surface of the heat-resistant protector 5 to make the When sound waves are oscillated, frictional heat is generated at the boundary surface between the outer coat 4 and the heat-resistant protector 5, whereby both can be thermally welded.

  Car cables are not arranged in a straight line in the car, but are routed to sew various parts. Therefore, the cable must be easy to bend along the route of the wiring, and therefore, the protector which is the outermost periphery of the cable needs to have heat resistance and durability and at the same time be soft to some extent. Therefore, the heat-resistant protector of the present invention preferably has a JIS A hardness of 85 or less, and a hardness exceeding this is not preferable because it is difficult to bend as a cable for an automobile and the cableability is poor.

Hereinafter, the present invention will be described in more detail by way of specific examples.
In addition, the raw material used in the Example is as follows.
TPO: olefin thermoplastic elastomer with a melt flow rate of 25 g / 10 min (Mitsui Chemicals, trade name: ML7030)
Polymethylpentene: Polymethylpentene having a melt flow rate of 21 g / 10 min (Mitsui Chemicals, trade name: TPX MX002)
EPDM rubber: Tubular EPDM rubber with A hardness 65, outer diameter φ13.5, inner diameter φ10.5 Silane-modified polypropylene: alkoxysilane-modified polypropylene with a melt flow rate of 16 g / 10 min (trade name: Link, manufactured by Mitsubishi Chemical Corporation) Ron XPM800HM)

  Using the above raw materials at each compounding ratio specified in Table 1 below, a single screw extruder (manufactured by Soken Co., Ltd.) with a screw diameter of 30 mm and a length / diameter ratio (L / D) = 22 pellets of a predetermined compounding ratio Was extruded at an extrusion temperature of 230 ° C. into tubes having an outer diameter of φ13.5 and an inner diameter of φ10.5, and heat resistant protectors of Examples 1 to 4 and Comparative Examples 1 to 4 were produced.

  The measurement method of the physical performance of the obtained product is as follows. The performance measured by these methods is summarized in Table 1.

A hardness According to JIS K6253 (hardness test method), A hardness hardness was determined using a durometer.

As wiring of protector, to confirm the insertion of the outer coat of the cable.

Using a heat-resistant temperature dynamic viscoelasticity measuring device RSAIII type (manufactured by T.A Instruments Co., Ltd.), the storage elastic modulus was measured in a tensile mode at a measurement frequency of 0.1 Hz and a heating rate of 2 ° C./min. The temperature when the value reached 10 ⁶ Pa was defined as the heat resistant temperature. It can be said that the higher the temperature, the higher the heat resistance.

Operation durability As shown in the schematic diagram of Fig. 2, the cable is routed on a bench equivalent to actual vehicle routing, the parking brake lever 6 and the parking brake 7 are connected, and the parking brake is operated 5 times at a connection ambient temperature of 170 ° C. The presence or absence of cracks and deformations harmful to the appearance of the protector was confirmed.

Heat sealability (pullout strength)
A protector was welded to the outer coat of the cable with the ultrasonic welder shown in FIG. 3, and the protector at that portion was pulled with a tensile tester (Tensilon) to determine the peel strength. 50N or more was accepted.

  In all the examples using the protector of the present invention, the A hardness was 85 or less and the flexibility was good because it had flexibility, but in Comparative Example 2, polymethylpentene exceeded the scope of the present invention. It was too hard and the routing was bad.

  Moreover, although all of the examples have a heat resistance temperature of 170 ° C. or higher and passed the 170 ° C. operation durability test, Comparative Example 1 has a low heat resistance temperature because polymethylpentene is below the range of the present invention. Cracks occurred.

  Further, in all the examples, the tensile strength was 120 N or more and the heat sealability was good, but Comparative Example 3 consisting only of thermosetting EPDM and Comparative Example including silane-modified polypropylene and exhibiting thermosetting properties No. 4 had extremely poor heat sealability. In Comparative Example 1, although the tensile strength exceeded 50N, it was less than 100N and was not good.

  As described above, it has been found that the heat-resistant protector of the present invention is flexible for a high heat-resistant temperature and has good heat sealability with the polypropylene outer coat material of the cable.

  A protector for an automobile control cable that has heat resistance and flexibility and can be easily welded to an outer coat resin can be easily provided.

C ... Control cable 1 ... Inner wire 2 ... Inner coat 3 ... Outer lower winding 4 ... Outer coat 5 ... Protector 6 ... Parking brake lever 7 ... Parking brake 8 ... Ultrasonic welding oscillation jig 9 ... Welding part

Claims (3)

  A heat-resistant protector for automobile cables, which is obtained by extruding into a tube a product obtained by adding 5 to 30 parts of polymethylpentene to 100 parts by weight of an olefin-based thermoplastic elastomer.   The heat-resistant protector for an automobile cable according to claim 1, wherein the olefin-based thermoplastic elastomer is obtained by dispersing a cross-linked ethylene-propylene copolymer rubber in a polypropylene resin.   An automotive cable, wherein the outer resin of the automotive cable is polypropylene, and the outer layer is coated with the heat-resistant protector according to claim 1 and then thermally welded.

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