JPH0656226B2 - Heat resistant tube - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to heat resistance and flexibility for protection and bundling of components used in a high temperature atmosphere in the field of automobiles, especially automobile electric wiring used around engine and the like. It is about excellent tubes.

Conventional technology Conventionally, polyamide is called engineering plastic because it has excellent mechanical strength and heat resistance.
It is widely used as a resin for injection molding in mechanical parts and electrical parts.

This polyamide is also used as a tube material, and nylon 11 and 12 tubes have been known so far.

By the way, when the tube is used as an underhood component for automobiles around the engine, the environmental temperature was about 120 ° C in the past, and it was sufficient if it had heat resistance equal to or higher than that. In recent years, along with the trend of increasing fuel consumption, the engine and its environmental temperature tend to become higher, so that higher heat resistance has been required.

A specific example of the use of a tube is to house a bundle of wires in the tube to protect and bundle the electrical wires in the vehicle engine compartment. In such a method of use, the tube may come into contact with the engine body due to vibrations, so the tube must have extremely high heat resistance.

When the tube is used for protection and binding of such automobile wiring, not only high heat resistance is required, but also the strength and flexibility are excellent and the weight is low, and the moldability of the material used is good. Is desirable. Engineering plastics are suitable as the material of the tube having such characteristics, and polyamide is considered to be particularly preferable. However, the tube made of conventionally known nylon 11 or 12 does not necessarily satisfy the above-mentioned required characteristics. In addition, nylon 66 and a copolymer containing nylon 66 as a main component have a drawback that the flexibility required as a tube cannot be obtained due to its high rigidity.

An object of the present invention is to protect automobile wiring that can be used under a high temperature atmosphere having excellent heat resistance, flexibility and strength, using a material having good moldability mainly composed of polyamide, and To provide a tube for unity.

Means for Solving the Problems As a result of various studies, the inventors have used a resin composition, which is obtained by blending a polyamide having a specific melting point with a certain polymer at a predetermined ratio, as a material. The inventors have found that the object can be achieved, and have completed the present invention based on this finding.

That is, the present invention molds a resin composition of (A) 97 to 55% by weight of a polyamide having a melting point of 230 ° C. or higher and (B) 3 to 45% by weight of an ethylene copolymer having a carbonyl group as a side chain. The present invention provides a heat-resistant tube for protecting and bundling automobile electric wiring.

By the way, a composition comprising a polyamide and an ethylene-based ionomer resin has already been proposed (Japanese Patent Publication No.
-4743), this is for improving the impact resistance of polyamide, and nothing is suggested about a heat resistant tube using the same.

The polyamide used as the component (A) in the resin composition used in the present invention is required to have a melting point of 230 ° C. or higher. For such a substance, nylon 66 and a copolymer containing nylon 66 as a main component are used. There is polyamide. Melting point 23
If the temperature is lower than 0 ° C, the heat resistance is not sufficient and it cannot be used, for example, around the engine of an automobile.

The molecular weight of this polyamide is not particularly limited,
It is preferably 17,000 or more.

In the resin composition used in the present invention, the polymer used as the component (B) is an ethylene polymer having a carbonyl group in its side chain.

Examples of the ethylene-based copolymer having a carbonyl group in the side chain as the component (B) include ethylene-based ionomer resins and modified ethylene-based copolymers. The ethylene ionomer resin is a copolymer composed of ethylene units (a) unsaturated carboxylic acid ester units (b) unsaturated carboxylic acid units (c) and unsaturated carboxylic acid metal salt units (d) (a), (b). ), (C) and (d) are constituent mol%,
(A) and (c) are arbitrarily greater than 0, and (b),
(D) is optional, preferably (a) is 90 to 98 mol%, and (b), (c) and (d) are of the formula Preferably Have a relationship of.

This unsaturated carboxylic acid ester unit is an unsaturated carboxylic acid having 3 to 8 carbon atoms, such as acrylic acid, methacrylic acid,
Derived from alkyl esters such as ethacrylic acid, examples of such alkyl esters of unsaturated carboxylic acids include methyl acrylate, ethyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, methacrylic acid. Methyl acid, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, isobutyl ethacrylate and the like can be mentioned.

The unsaturated carboxylic acid unit is a unit derived from the unsaturated carboxylic acid used in the unsaturated carboxylic acid ester unit, and the unsaturated carboxylic acid metal salt unit is a unit derived from the metal salt of the unsaturated carboxylic acid. Is. The metal species of the unsaturated carboxylic acid metal salt include I of the periodic table.
Group A, IB, IIA, IIB, IIIA and VIII Group 4 metals such as Na, K, Cu, Mg, Ca, Ba, Zn,
Cd, Al, Fe, Co, Ni and the like, and particularly preferable are
Na, K, Mg, Ca, Ba and Zn.

On the other hand, the modified ethylene copolymer is an ethylene copolymer grafted with an unsaturated dicarboxylic acid or a derivative thereof, and as the unsaturated dicarboxylic acid or its derivative to be grafted, maleic acid, fumaric acid, itacone is used. acid,
Tetrahydrophthalic acid, endo-cis-bicyclo [2,2,
1] Unsaturated dicarboxylic acids such as hept-5-ene-2,3-digalbonic acid, acid anhydrides of these unsaturated dicarboxylic acids, esters, derivatives such as acid halides can be mentioned. Among these, particularly preferred are maleic anhydride, itaconic anhydride and endo-cis-bicyclo.
It is [2,2,1] hept-5-ene-2,3-digalbonic acid anhydride.

As a method of grafting these unsaturated dicarboxylic acids or their derivatives onto the ethylene-based copolymer, a known method using a radical polymerization initiator, ultraviolet rays or the like can be adopted. Usually, a method of uniformly blending an ethylene copolymer, an unsaturated dicarboxylic acid or a derivative thereof and a radical polymerization initiator, and melt kneading, or dissolving the ethylene copolymer in a solvent, unsaturated carboxylic acid and A method of adding a radical polymerization initiator is used. The radical polymerization initiators used in these graft reactions include organic peroxides, organic peresters and azo compounds, but preferably organic peroxides such as di-tertiary butyl peroxide and dicumyl peroxide are used. It

The ethylene copolymer used for the modified ethylene copolymer is composed of a copolymer of ethylene and an α-olefin having 3 or more carbon atoms, and α-olefin component units include propylene, butene-1, and hexene- 1, 4-methylbutene-1, 4-methylpentene-1, decene-1, hexadecene-1, eicosene-1 and the like,
These are one kind or a mixture of two or more kinds. Particularly preferred are propylene and butene-1. In addition to ethylene and α-olefin, this ethylene-based copolymer includes methylene norbornene, ethylidene norbornene, 1,4-
It may be a terpolymer containing a non-conjugated diene such as hexadiene or dicyclopentadiene. The proportion of each component of the ethylene copolymer is not particularly limited, but the ethylene content is preferably in the range of 60 mol% to 95 mol%.

The resin composition used in the tube of the present invention comprises 97 to 55% by weight of polyamide as the component (A) and polymer 3 to 45 as the component (B).
%, Preferably 95-70% by weight of component (A), and (B)
It is a mixture of 5 to 30% by weight of the components. When the content of the polyamide as the component (A) exceeds 97% by weight, the resulting tube loses flexibility and is easily broken when bent in a low moisture state, and when it is less than 55% by weight, it becomes too soft and slightly. It can be deformed by various forces, and burrs easily appear during molding, so only products with low product value can be obtained.

The method for preparing the resin composition is not particularly limited, and any method can be used, but a method of melt-kneading the components (A) and (B) using an extruder having good kneading properties. Is preferred.

Further, in the melt-kneading, in addition to the components (A) and (B), if necessary, a dye, a pigment, a flame retardant, a heat-resistant agent, a weather-resistant agent, a lubricant, a plasticizer, a filler, etc. may be added in an appropriate amount. Other polymers may be added within a range not departing from the object of the present invention.

In the present invention, the melt intex [MI] of the resin composition is obtained by using an apparatus specified in ASTM D 1238,
The value measured at a temperature of 300 ° C and a total load of 3.8 kg is preferably 0.05.
It is desirable to be in the range of up to 500 g / 10 minutes, more preferably 0.1 to 200 g / 10 minutes. When the MI is less than 0.05 g / 10 minutes, the load of the extruder is increased, the productivity is lowered, and the temperature of the composition itself needs to be extremely high at the time of molding to form the composition ( A) component polyamide and (B)
Ingredients accelerate the decomposition of the polymer, while MI is 500g / 10
If the amount exceeds the limit, drawdown during extrusion molding will be significant, and it will be difficult to obtain a tube-shaped molded product.

In forming the tube of the present invention, the molding method is not particularly limited, but extrusion molding or blow molding is generally used. For example, a tube can be obtained by charging the resin composition into a hopper of an extruder, sending the composition to the tip of the screw while melting the composition by rotating the screw, extruding a cylindrical parison from the die, and cooling. At this time, a corrugated shape can be formed by using a mold as desired.

The shape of the tube of the present invention is not particularly limited,
Usually made cylindrical. Particularly preferable is a corrugated tube, but a tube having an outer slit can be used.

EFFECTS OF THE INVENTION The heat resistant tube of the present invention has excellent characteristics such as high moldability, high strength and excellent heat resistance, and excellent flexibility and light weight. It is suitable as a tube for protecting and bundling electric wiring in an automobile engine room used.

EXAMPLES Next, the present invention will be described in more detail with reference to Examples.

As the ethylene-based ionomer resin, Himilan 1706 manufactured by Mitsui DuPont Co., Ltd. was used, and the modified ethylene-based copolymer was obtained as follows.

Preparation of Modified Ethylene Copolymer EP02P [Nippon Synthetic Rubber Co., Ltd. ethylene / propylene copolymer] 100 parts by weight, maleic anhydride 1 part by weight, Hexa-25B [NOF Corporation radical polymerization initiator] After blending 0.3 parts by weight, extrude with the same direction twin-screw extruder,
Pelletized. Vacuum dryer (160 ℃, 1mmHg)
After being dried for 20 hours, a modified ethylene-based copolymer grafted with 0.5 g of maleic anhydride per 100 g of the ethylene-based copolymer was obtained.

Examples 1 to 4 A resin composition having a composition as shown in Table 1 was kneaded by a twin-screw extruder to be pelletized, and then the pellet was supplied to a blow molding machine to have a diameter of 10 mm and a thickness of 0.2 mm. Manufactured a tube of.

This tube was left in a temperature atmosphere as shown in Table 1 for a predetermined time and then bent 180 °, and the state was observed to determine heat resistance. The results are shown in Table 1.

Comparative Example A tube was manufactured and tested in the same manner as in Examples 1 to 4 using nylon 66 pellets. The results are shown in Table 1.

(Note) Good in the heat resistance column indicates that it can be easily bent and no significant change in shape is observed.

Examples 5 to 8 As shown in Table 2, the relative viscosity of nylon 66 was changed to change the MI of a resin composition comprising 80% by weight of nylon 66 and 20% by weight of an ethylene-based ionomer resin, and this resin composition was used. Then, it was molded in the same manner as in Examples 1 to 4 and its blow-molded raw material was evaluated. The results are shown in Table 2.

Example 9 The same polyamide resin composition pellets as in Example 7 were used to obtain a wall thickness of 0.
When supplying and extruding to a 50 mmφ single-screw extruder equipped with a spinneret that can be molded into a tube with a diameter of 5 mm and an outer diameter of 10 mmφ, air is introduced into the hollow part to form a cylindrical tube, and then a corrugated metal The gulgate tubes shown in FIG. 1 were continuously obtained while being collected by a tube collecting machine with a mold. There was no problem in extrusion moldability.

[Brief description of drawings]

FIG. 1 shows a corrugated tube obtained from the composition of the present invention.

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Claims (6)

[Claims] 1. (A) Polyamide 97-55 having a melting point of 230 ° C. or higher
A heat-resistant tube for protecting and binding automobile electric wiring, which is formed by molding a resin composition of 3% by weight to 45% by weight of (B) an ethylene-based copolymer having a carbonyl group as a side chain. 2. A heat resistant tube for protecting and binding automobile electric wiring according to claim 1, wherein the component (A) is nylon 66 or a copolymer containing nylon 66 as a main component and having a melting point of 230 ° C. or higher. . 3. A heat-resistant tube for protecting and binding automobile electric wiring according to claim 1 or 2, wherein the component (B) is an ethylene ionomer resin. 4. A heat-resistant tube for protecting and binding automobile electric wiring according to claim 1 or 2, wherein the component (B) is a maleic anhydride-modified polyolefin. 5. The melt index of the resin composition is 0.05.
The heat-resistant tube for protecting and binding automobile electric wiring according to any one of claims 1 to 4, which has a temperature of 300 to 500 g / 10 minutes (temperature 300 ° C, total load 3.8 kg). 6. A heat-resistant tube for protecting and binding automobile electric wiring according to any one of claims 1 to 5, which is a corrugated tube.