JPS5812299B2 - Polyolefin insulators - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyolefin composition with excellent adhesion to metals.

To improve the adhesion of polyethylene coatings to metals,
A method has been proposed that uses polyethylene modified with unsaturated carboxylic acids such as acrylic acid, maleic acid, maleic anhydride, and methyl acrylate, their anhydrides, or their esters. Adhesion to was improved.

However, even the modified polyethylene obtained by this method cannot be used in applications that require strong adhesive strength, such as inner coating of water pipes that require durability, laminated sheaths, and gables for telephone wires. Also, it could not be said that the adhesive strength was sufficient.

The present invention is a modified polyethylene composition intended to further improve the adhesion of a polyethylene film to metal.

That is, the present invention consists of 70 to 95% by weight of polyethylene partially or wholly modified with unsaturated carboxylic acid or its anhydride and 5 to 30% by weight of polypropylene, and the unsaturated carboxylic acid or its anhydride contained by the modification. This is a polyolefin composition having excellent metal adhesion properties, characterized in that the amount of the carbonyl group per composition 19 is in the range of Ix10-4 to 1x10-1 mmol equivalent.

The unmodified polyethylene used in the composition of the present invention includes low density polyethylene, medium density polyethylene, and high density polyethylene.

These polyethylenes may be ethylene homopolymers, or polyethylene copolymers made by copolymerizing ethylene with polymer components such as propylene, 1-butene, vinyl acetate, and acrylic esters. .

Furthermore, two or more types of polyethylenes may be used in combination.

Furthermore, as the polypropylene used in the composition of the present invention, in addition to propylene homopolymers, polypropylene copolymers containing propylene as a main component and copolymerizing components such as ethylene and 1-butene may be used. Ru.

In the composition of the present invention, the unsaturated carboxylic acid or its anhydride used to modify part or all of the polyethylene includes acrylic acid, methacrylic acid,
Examples include maleic acid, maleic anhydride, fumaric acid, citraconic acid, citraconic anhydride, itaconic acid, and itaconic anhydride. Among these, maleic acid and maleic anhydride are particularly preferred.

The amount of units of these unsaturated carboxylic acids or their anhydrides contained by modification in the composition of the present invention is IX 1 0-4 as carbonyl group per 1 g of the composition.
It is necessary that the amount is 1 to 1 mmol equivalent of IXIO.

If the amount of unsaturated carboxylic acid or its anhydride unit contained by modification is less than I
Even if the amount is more than -1 IJ molar equivalent, the effect of improving adhesion will be small.

In order to produce polyethylene modified with an unsaturated carboxylic acid or its anhydride, these modified monomers can be copolymerized at the stage of polymerizing ethylene in advance,
Although it is also possible to graft-copolymerize polyethylene once polymerized with these modifying monomers, the latter method of modifying by graft copolymerization is preferred.

Various conventionally known methods can be used to modify polyethylene by craft copolymerization with the unsaturated carboxylic acid or its anhydride.

For example, it can be produced by heating a mixture of polyethylene, an unsaturated carboxylic acid or its anhydride, and a solvent to a high temperature in the presence or absence of a radical initiator such as an organic peroxide; It can also be produced by simply melt-mixing a mixture of polyethylene and an unsaturated carboxylic acid or anhydride thereof without using polyethylene.

The present invention shows that when unmodified polypropylene is blended with polyethylene that has been partially or completely modified with an unsaturated carboxylic acid or its anhydride, the adhesion to metals is significantly improved compared to modified polyethylene that does not contain polypropylene. This is what I discovered.

The composition ratio of polypropylene in the composition of the present invention needs to be 5 to 30% by weight, particularly 7 to 15% by weight.
Preferably, it is % by weight.

If the composition ratio of polypropylene is less than 5% by weight, a sufficient effect of improving metal adhesion will not appear, and if it is more than 30% by weight, the effect of improving adhesion will be reduced.

As a practical aspect of producing the composition of the present invention, it is possible to modify all of the polyethylene used with an unsaturated carboxylic acid or its anhydride, and then blend unmodified polypropylene, or to use it. It is also possible to partially modify the polyethylene with an unsaturated carboxylic acid or its anhydride and then blend it with unmodified polyethylene and polypropylene, or the latter method is preferred for industrialization.

In either case, it is necessary that the composition ratio of polypropylene in the composition and the amount of unsaturated carboxylic acid or its anhydride units contained by modification are within the above-mentioned ranges.

The composition of the present invention has improved adhesion to metals such as iron, aluminum, copper, and lead, compared to conventionally used compositions in which polyethylene is modified with unsaturated carboxylic acids or their anhydrides. It is suitable for applications that require strong adhesive strength and durability, such as inner coating of water pipes, laminated sheathed telephone wires, and cables.

Next, the present invention will be specifically explained using actual cases.

Note that modified polyethylene was prepared according to Reference Examples 1 to 3.

These modified polyethylenes were used to prepare the composition of the present invention according to the actual example, and an adhesion test to an aluminum plate or a steel plate was conducted.

The aluminum plate has a thickness of 200μ and a size of 14
0mm x 140wm soft aluminum plate (JIS
-H4000) as an iron plate with a thickness of 1 mm and a size of 1
40mm x 140mm hot rolled steel plate (J
Is-88 41 ) were each used after being defatted.

As for the adhesion method, the internal size is 140mm x 140m.
The above aluminum test piece or iron plate test piece was placed inside an iron frame that was 1 mm thicker than the above test piece, and enough molten resin was placed on top of it to form a 1 mm thick film, and then pressed. After heating at 200° C. for 5 minutes on a molding machine, it was further pressurized to 50 kg/cm 2 at that temperature for 3 minutes, and then cooled.

This coated test piece was cut into 2 cfrL width, and a portion of each end was forcibly peeled off using a knife, and then a peel test was performed using an Instron at a speed of 100 mm/min to determine the average value of peel strength.

Reference Example 1 Preparation method of maleic anhydride graft copolymer of high-density polyethylene High-density polyethylene (manufactured by Mitsui Petrochemicals, trade name HIZEX 1300J, density 0.965, Tart index 14), xylene as a solvent, radical initiation A modified high-density polyethylene was prepared by graft-copolymerizing maleic anhydride by heating to 125° C. with maleic anhydride in the presence of digyl peroxide as an agent.

The carbonyl group content of this modified high-density polyethylene is 0.
It was 1 mmol equivalent/1 g.

Reference Example 2 Preparation of Maleic Acid Graft Copolymer of Medium Density Polyethylene Medium density polyethylene (manufactured by Mitsui Petrochemicals, trade name Fuosex 45300, density 0.944, melt index 35) was treated with a radical initiator. Modified medium density polyethylene was prepared by melt-mixing with maleic acid in the presence of dicumyl peroxide and graft copolymerizing maleic acid.

The carbonyl group content in this modified medium density polyethylene is 0
．． The amount was 71 g with a 3 mmol equivalent.

Reference Example 3 Preparation method of maleic anhydride graft copolymer of low density polyethylene Low density polyethylene (manufactured by Mitsui Polychemical Co., Ltd., trade name Mirason M-11, density 0.917, Tart index 6.5) as a solvent Modified polyethylene was prepared by graft copolymerizing maleic anhydride by heating with maleic anhydride in the presence of xylene and dicumyl peroxide as a radical initiator.

The carbonyl group content in this modified polyethylene is 0.02
It was millimole equivalent/1 g.

Actual Sister Examples 1 to 6, Comparative Examples 1 to 9 A composition was prepared by blending the modified polyethylene prepared in the reference example with the polyethylene and polypropylene shown in Table 1,
A test piece was prepared by coating this on an aluminum plate according to the method described above, and the adhesive strength was measured.

The results are summarized in Table 1. Actual winding examples 7 to 9, comparative example 1
0 to 15 A composition is prepared by blending the modified polyethylene prepared in the reference example with the polyethylene and polypropylene shown in Table 2,
A test piece was prepared by coating this on an iron plate according to the method described above, and the adhesive strength was measured.

The results are summarized in Table 2.

Claims (1)

[Claims] 1 Consists of 70 to 95 parts by weight of polyethylene partially or wholly modified with an unsaturated carboxylic acid or its anhydride and 5 to 30 parts by weight of polypropylene, and the amount of the unsaturated carboxylic acid or its anhydride contained by modification is 1 x 10 carbonyl groups per composition 19
A polyolefin composition having excellent metal adhesion properties, characterized in that the amount thereof is in the range of -4 to 1 x 10-1 millimolar equivalents.