JPH0319058B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a resin-metal laminate, and more particularly to a resin-metal laminate that has high adhesive strength, excellent environmental stress cracking resistance, and resistance to hot salt water, and is particularly suitable for coating steel pipes. be. Conventionally, materials in which polyolefin is laminated with metals such as iron and aluminum have been widely used for the purpose of protecting metals. However, since polyolefins are generally nonpolar, their adhesion to metals is extremely poor. In order to improve this adhesion, a method using maleic anhydride-modified polyolefin as an adhesive layer between the metal and polyolefin (Japanese Patent Publication No.
10757, etc.), but the adhesive strength is still insufficient and the environmental stress cracking resistance (ESCR) is poor. It has also been proposed to improve adhesion by blending a hydrocarbon-based synthetic elastomer with acid-modified polyolefin (Japanese Patent Application Laid-open No. 80334/1983).
However, there is a problem that heat resistance and solvent resistance decrease. In particular, when coating the surface of steel pipes that are placed underground or in water such as seawater, it is important to have excellent primary properties such as adhesive strength, as well as secondary properties such as ESCR and resistance to hot salt water. required. Therefore, as a result of intensive study on resin-metal laminates with excellent adhesive strength, ESCR, etc., the present inventor found that
The invention has been completed. That is, the present invention provides (A) high-density polyethylene or low-density polyethylene modified with an unsaturated carboxylic acid or a derivative thereof, or the modified polyethylene and unmodified polyethylene, ethylene-vinyl acetate copolymer, ethylene-propylene rubber. and a thermoplastic polyolefin elastomer, 55 to 99% by weight of a modified polyethylene resin containing 0.001 to 1.0% by weight of the unsaturated carboxylic acid or its derivative, and a density of 0.900 to 0.90%.
0.930g/ ^cm3 , melt index 0.1~25g/10
This is a resin-metal laminate formed by laminating a resin layer consisting of 45 to 1% by weight of butene-1 polymer and (B) a metal layer consisting of iron or aluminum. (A) The resin layer (hereinafter referred to as layer A) is made of high-density polyethylene (modified high-density polyethylene) or low-density polyethylene (modified low-density polyethylene) modified with unsaturated carboxylic acid or its derivative, or It consists of a mixture of modified polyethylene and unmodified polyethylene, ethylene-vinyl acetate copolymer, ethylene-propylene rubber, and thermoplastic polyolefin elastomer, and contains the unsaturated carboxylic acid or its derivative.
It consists of a modified polyethylene resin containing 0.001 to 1.0% by weight and 45 to 1% by weight of butene-1 polymer having a density of 0.900 to 0.930 g/cm ³ and a melt index of 0.1 to 25 g/10 min. That is, the modified polyethylene resin in the present invention is
It means modified high-density polyethylene, modified low-density polyethylene, or a mixture of the modified polyethylene and any one of unmodified polyethylene, ethylene-vinyl acetate copolymer, ethylene-propylene rubber, and thermoplastic polyolefin elastomer. As the polyethylene to be modified, high-density polyethylene or low-density polyethylene is used as described above. Examples of unsaturated carboxylic acids used for modifying polyethylene include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, citraconic acid, sorbic acid, mesaconic acid, and angelic acid. In addition, its derivatives include acid anhydrides, esters, amides, imides, metal salts, etc., such as maleic anhydride, itaconic anhydride,
Citraconic anhydride, methyl acrylate, methyl methacrylate, ethyl acrylate, butyl acrylate, maleic acid monoethyl ester, acrylamide, maleic acid monoamide, maleimide, N
-butylmaleimide, sodium acrylate, sodium methacrylate and the like. The method for modifying polyethylene with these unsaturated carboxylic acids or derivatives thereof is not particularly limited, and various known methods can be used. For example, the process proceeds by adding a radical initiator to polyethylene and maleic anhydride in the presence or absence of a solvent and heating the mixture. During the reaction, other vinyl monomers such as styrene or rubbers such as liquid rubber and thermoplastic rubber may also be present. The amount of acid addition in the modified polyethylene thus obtained is 0.001 to 5% by weight, preferably 0.5 to 3% by weight.
Weight%. The modified polyethylene resin described above may be used as it is, but it is preferably mixed and diluted with unmodified polyethylene, ethylene-vinyl acetate copolymer, ethylene-propylene rubber, or thermoplastic polyolefin elastomer, and finally acidified. The content is usually in the range of 0.001 to 1.0% by weight, preferably 0.01 to 0.6% by weight, particularly preferably 0.05 to 0.4% by weight. acid content
If it is less than 0.001% by weight, the adhesion will decrease and 1.0
If it exceeds % by weight, the strength, ESCR, etc. of the resin layer will decrease, making it impossible to put it into practical use. Here, as the unmodified polyethylene, high-density polyethylene, medium/low-density polyethylene, linear low-density polyethylene, etc. can be used. There are no restrictions on the ethylene-vinyl acetate copolymer, but the vinyl acetate content
10 to 40% by weight is preferably used. Examples of the ethylene-propylene rubber include ethylene-propylene copolymer and ethylene-propylene-dien terpolymer. The modified polyethylene resin serves as the base for layer (A) and is used in a proportion of 55 to 99% by weight, preferably 85 to 95% by weight. Next, butene-1 polymer is added to improve adhesive strength and ESCR;
A homopolymer of 1 or a copolymer with other α-olefins such as ethylene, propylene, etc. can be used. This copolymer is obtained by regular polymerization using butene-1 monomer and other α-olefin monomers as raw materials. In addition, other α−
When using olefin monomer, its content is
It should be less than 20% by weight, preferably less than 10% by weight. Butene-1 polymer has a density of 0.900 to 0.930 g/cm ² ,
Preferably 0.905 to 0.920 g/cm ² , melt index (MI) 0.1 to 25 g/10 min, preferably 0.3 to
3.0g/10 minutes is preferably used. MI is 0.1
If it is less than 25 g/10 minutes, the dispersibility will be poor and the reforming effect will be insufficient, and if it exceeds 25 g/10 minutes,
ESCR worsens, which is not desirable. The amount of butene-1 polymer blended is 45-1% by weight, preferably 15-5% by weight. When it exceeds 45% by weight, the adhesiveness decreases, and when it is less than 1% by weight, the adhesiveness decreases and the improvement in ESCR becomes insufficient. The resin of layer (A) is obtained by kneading the above two components. The kneading may be carried out by a conventional method, for example, using an extruder, a Banbury mixer, or the like. Next, iron or aluminum is used as the B metal layer (hereinafter referred to as (B) layer). The laminate of the present invention is obtained by laminating the above layer A and layer B. In this case, the thickness of layer A is
200 to 500μ is appropriate. As for the lamination method, it is sufficient to apply a commonly used method. Generally, the surface of the B layer is heated to 100 to 150°C, and then the A layer sheet with a surface temperature of 180 to 230°C is laminated. Laminate. Alternatively, stack A layer and B layer at 130-200℃.
A laminate can be obtained by heating, melting and pressing at a temperature of 1 to 10 kg/cm ² for 0.1 to 10 minutes. In the present invention, since the butene-1 polymer is added to the A layer, the adhesive strength with the B layer is high, and strong adhesion can be achieved at low temperature in a short time. In addition to the above laminate, the present invention naturally includes a laminate with an adhesive layer interposed between the polyethylene resin layer and the metal layer. Here, a known adhesive is used as the adhesive layer, such as a thermoplastic epoxy resin adhesive or a thermosetting epoxy resin adhesive. Regarding thermosetting epoxy resin adhesives,
Adhesive is applied to the metal surface in advance, and after semi-curing or curing is completed, it is fused and laminated with polyethylene resin. The thickness of these adhesive layers is 5~
A thickness of about 100μ is sufficient, and by employing this method, not only the interlayer adhesive strength can be further improved, but also the hot water resistance can be improved. In the present invention, it goes without saying that other materials such as thermoplastic resins such as polyolefin and polyamide, and metals may be further laminated on the resin layer having excellent adhesive properties, if necessary. As detailed above, the resin-metal laminate of the present invention has extremely high adhesive strength between the two, and is also excellent in solvent resistance, heat resistance, environmental stress cracking resistance, etc. Therefore, not only coated steel pipes but also
It can be effectively used as building materials, packaging containers, food containers, etc. Next, the present invention will be explained in detail with reference to examples.
The evaluation of the test was conducted as follows. 90° peel strength: indicates the peel strength between layers A and B. Warm salt water peeling: Resin-metal laminate in 3% saline solution at 80°C
After being immersed at ℃ for one week, the area of peeling between layer A and layer B is expressed as a percentage. ESCR: _f50 value according to ASTM-D-1693. Examples 1 to 11 and Comparative Examples 1 to 4 A modified polyethylene resin and a butene-1 polymer were dry blended in the proportions shown in Table 1, and then heated and kneaded to obtain an A-layer resin. Next, the above A-layer resin sheet (thickness 500μ) is layered on the B-layer metal plate, and the density
0.95g/cm ² , MI 0.15g/10min high-density polyethylene sheets (thickness 2mm) are stacked at 130℃, 10Kg/cm ²
The resin-metal laminate was produced by heating and melting and pressing for 10 minutes. Table 1 shows the test results of the obtained laminate.

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Claims (1)

[Claims] 1 High-density polyethylene or low-density polyethylene modified with an unsaturated carboxylic acid or its derivative, or the modified polyethylene and unmodified polyethylene, ethylene-vinyl acetate copolymer,
consisting of a mixture of ethylene-propylene rubber and a thermoplastic polyolefin elastomer, containing the unsaturated carboxylic acid or its derivative.
Modified polyethylene resin containing 0.001-1.0% by weight
A resin layer consisting of 45-1% by weight of a butene-1 polymer with a density of 0.900-0.930 g/cm ³ and a melt index of 0.1-25 g/10 min, and (B) a metal layer consisting of iron or aluminum. A resin-metal laminate made by laminating two layers.