JPH06248248A - Laminate of polyethylene to metal - Google Patents

Abstract

PURPOSE:To provide the subject laminate improved in the corrosion resistance of the metal and in appearance and good in the adhesion between the polyethylene and the metal under a warm water condition and an alkaline condition by using a specific modified polyethylene composition as an adhesive layer. CONSTITUTION:The laminate is characterized by using a modified polyethylene composition as an adhesive layer, the modified polyethylene composition being produced by modifying (A) 100 pts.wt. polyethylene (preferably linear low density polyethylene) containing <=50wt.% of an olefinic rubber (e.g. ethylene-propylene eopolymer rubber) with (B) 0.5-20 pts.wt. of unsaturated glycidyl compound (preferably glycidyl methacrylate). The modified polyethylene composition is preferably produced e.g. by feeding the polyethylene, the olefinic rubber, the component B and a catalyst such as benzoyl peroxide into an extruder and subsequently melt-kneading the mixture at 170-300 deg.C for 0.1-20min. When the adhesive layer, the polyethylene and the metal are laminated to each other, the metal and the resin are preferably held at temperatures of 160-200 deg.C and 180-230 deg.C, respectively.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a laminate of polyethylene and metal. More specifically, the present invention relates to a laminate of metal and polyethylene, which has a modified polyethylene as an adhesive layer and has an improved adhesive force with a metal.

[0002]

2. Description of the Related Art Conventionally, in order to improve corrosion resistance, appearance, food hygiene and other problems of metals, various synthetic resins are coated and laminated on the inner and outer surfaces of metal tubes, metal plates, electric wires, wires and the like. Is being done. Polyolefin, which has excellent physical and chemical properties, has been attracting attention as a coating layer for metal, but it has a drawback that it has weak adhesion to metal because it is non-polar. Therefore, various proposals have been made to improve this drawback. For example, high-pressure method low-density polyethylene, low-pressure method high-density polyethylene or polypropylene with 1 to 1 rubber compound
A method of using 20 parts by weight of a modified polyolefin modified with an unsaturated carboxylic acid has been disclosed (JP-A-52-8035). However, this method improves the adhesiveness but does not cause environmental stress cracking. There is a problem in that the improvement of the properties and high-speed tensile elongation is not sufficient.

As a laminate that solves this problem, there is a laminate having a resin composition obtained by reacting a mixture of linear low-density polyethylene and synthetic rubber with an unsaturated carboxylic acid or a derivative thereof as an adhesive layer (Japanese Patent Publication No. 62-62). -14176 publication). According to this laminate, a normal construction state (-30 to 50 ° C, pH 3 to
8), a sufficient adhesive strength is maintained, but there is a drawback that the adhesive strength is likely to be lowered in high temperature water of 80 ° C. or higher or in an alkaline atmosphere. Therefore, an object of the present invention is to provide a polyethylene-based laminate which has a sufficient adhesive force to a metal and does not deteriorate in adhesion strength in high temperature water of 80 ° C. or higher or in an alkaline atmosphere.

In recent years, as a technique related to the present invention, an epoxy-containing acrylamide monomer has attracted attention as a modifier for polyolefins (International Publication WO91 / 1).
4717, Japanese Patent Laid-Open Nos. 3-285931 and 3-285932). International publication
WO91 / 14717 describes a modified polyolefin resin which has no odor at the time of modification and has excellent adhesiveness to a filler, a metal and a polymer resin substrate, and the modified resin and another thermoplastic resin (polyester, polyphenylene sulfide, Polycarbonate, polyamide, etc.) is disclosed, and N is used as an example of the modified polyolefin resin coating.
-[4- (2,3-Epoxypropoxy) -3,5-dimethylbenzyl] acrylamide-modified polypropylene resin and polyethylene resin degreased soft aluminum plate and steel plate sheet that are heat press-bonded have excellent peel strength. There is a statement to the effect. However, there is no prior art that describes a laminate of polyethylene and a metal having a modified polyethylene as an adhesive layer, which is an object of the present invention and has a low adhesive strength in high temperature water of 80 ° C. or higher and in an alkaline atmosphere. .

[0005]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, modified polyethylene obtained by modifying polyethylene with an unsaturated glycidyl compound, particularly preferably an appropriate amount of olefinic rubber is converted into polyethylene. It was found that a laminate of a metal and a polyethylene having a modified polyethylene modified with an unsaturated glycidyl compound as a resin composition blended with the adhesive layer has excellent adhesion to the metal under high temperature water conditions and alkaline conditions, The present invention has been reached.

That is, the present invention relates to a laminate with a metal having an adhesive layer of a modified polyethylene composition obtained by modifying 100 parts by weight of polyethylene containing up to 50% by weight of an olefinic rubber with 0.5 to 20 parts by weight of an unsaturated glycidyl compound. Is.

The present invention will be described in detail below. The modified polyethylene used in the present invention is polyethylene alone or polyethylene obtained by modifying a resin composition composed of polyethylene and an olefin rubber with an unsaturated glycidyl compound. Here, polyethylene has a density of 0.915 to 0.945.
g / cm ³ , melt index (MI, 190 ℃, 2.16kg
Load) 0.1 to 30 g / 10 minutes, other α-
It may be copolymerized with about 20% by weight or less of an olefin. Examples of such polyethylene include low-pressure high-density polyethylene (HDPE), high-pressure low-density polyethylene (LLDPE), and linear low-density polyethylene (LLDP).
E) and the like, among which environmental stress crack resistance (ESC)
R) and linear low density polyethylene (L
LDPE) can be preferably used.

The olefin rubber is ethylene-
They are α-olefin copolymer rubber, polyolefin rubber and polydiolefin rubber. As the ethylene-α-olefin copolymer rubber, ethylene, propylene,
It means a copolymer rubber with one or more α-olefins other than ethylene, such as 1-butene, 1-hexene, and 4-methylpentene-1. As the polymer rubber of ethylene and one or more kinds of α-olefins other than ethylene, typically, ethylene-propylene copolymer rubber (EPR) and ethylene-butene copolymer rubber (EBR) are used. , Ethylene-propylene-diene copolymer rubber (EPDM) and the like. As the diene in the ethylene-propylene-diene copolymer rubber (EPDM), a non-conjugated diene such as dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylenenorbornene or a conjugated diene such as butadiene or isoprene is used. be able to.

The ethylene content in the ethylene-α-olefin copolymer rubber is 5 to 95% by weight, preferably 10 to 90% by weight. When the ethylene content is less than 5% by weight or exceeds 95% by weight, it becomes difficult to exhibit properties as a rubber. Such an ethylene-α-olefin copolymer rubber has a crystallinity of usually 40% by weight or less and a Mooney viscosity (ML _{1 + 4} 100 ° C.) of 10
It preferably has a physical property of 150 to 150 and a density of 0.9 g / cm ³ or less, and particularly has a tensile rigidity of 1000 kg / cm ² or less.

Specific examples of the polyolefin rubber include polyisobutylene (PIB) and the like, and examples of the polydiolefin rubber include polybutadiene and polyisoprene. Those having a Mooney viscosity of 10 to 150 and a degree of crystallinity of 30% by weight or less are preferable.

The olefinic rubber used in the present invention may contain other repeating units derived from other α-olefins such as 4-methylpentene-1 within a range that does not impair the properties thereof. You may contain up to the ratio of 10 mol% or less.

In the present invention, the modified polyethylene used as the adhesive layer may be polyethylene modified with an unsaturated glycidyl compound, but a composition containing an olefinic rubber is preferably modified with an unsaturated glycidyl compound. That is, in the present invention, the compounding ratio of the olefin rubber is 100 to 50% by weight of polyethylene, preferably 80 to 70% by weight, and the olefin rubber is 0%.
-50% by weight, preferably 20-30% by weight. If the olefin rubber is not blended, the adhesive strength with the metal is low, and if it exceeds 50% by weight, the heat resistance is lowered, which is not preferable.

Further, in the present invention, other polyolefin may be contained in addition to the above-mentioned polyethylene and olefin rubber. Other polyolefins include homo-, random-, block-polymers of polypropylene, or propylene-non-conjugated diene copolymers (PP
DM), polybutene-1 (PB-1), and the like. These can be contained in an amount that does not significantly impair the embrittlement temperature of the polyethylene, that is, about 50% by weight.

In the present invention, the unsaturated glycidyl compound used as the modifier is represented by the general formula (I)

[0015]

[Chemical 1] [In the formula, R is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, Ar is an aromatic hydrocarbon group having 6 to 20 carbon atoms having at least one glycidyloxy group, and n
Represents an integer of 1 to 4. ], General formula (II)

[0016]

[Chemical 2] [In the formula, R represents the same meaning as described above. ] Or general formula
(III)

[0017]

[Chemical 3] [In the formula, X represents a methylene group or a phenylene group,
R has the same meaning as described above. ] It is a polymeric compound shown by these. Of these, the general formula (I) and the general formula (I
The compounds represented by I) are preferred. Among the unsaturated glycidyl compounds represented by the general formula (I), the compounds represented by the following general formula are particularly preferable.

[0018]

[Chemical 4] [In the formula, R represents the same meaning as described above. Such a glycidyl compound can be produced, for example, by the method described in JP-A-60-130580.

The unsaturated glycidyl ester represented by the general formula (II) and the unsaturated glycidyl ether represented by the general formula (III) include glycidyl acrylate, glycidyl methacrylate (GMA), allyl glycidyl ether and 2-methylallyl. Examples thereof include glycidyl ether and styrene-p-glycidyl ether, and among them, glycidyl methacrylate (GMA) is preferable. These polymerizable compounds are usually used alone, but may be used in combination of two or more kinds.

The amount of the modifier compounded cannot be generally specified because it varies depending on the composition of the raw material resin, but generally it is about 0.5 to 20 parts by weight, preferably 1 to 10 parts by weight, relative to 100 parts by weight of the raw material resin. . If the blending amount is less than 0.5 parts by weight, the adhesion strength to the metal will be insufficient, and if the blending amount exceeds 20 parts by weight, the properties of polyethylene itself will change, which is not preferable.

Such modified polyethylene can be obtained by utilizing a known modification method such as a solution method or a melt kneading method. In addition, a desired product may be appropriately selected and used from commercially available products. A method by graft polymerization will be described as a specific example of the modification method.

In the melt-kneading method, polyethylene, olefinic rubber, the above-mentioned glycidyl compound and, if necessary, a catalyst are used, and these components are put into an extruder, a twin-screw kneader or the like, and heated to about 170 to 300 ° C. The modified polyethylene is obtained by kneading for about 0.1 to 20 minutes while heating to a temperature and melting. In the case of the solution method, the above-mentioned starting materials are dissolved in an organic solvent such as xylene, and modification is carried out while stirring at a temperature of about 90 to 200 ° C for 0.1 to 100 hours.

The order of denaturation is not particularly limited, and for example,
It can be carried out by a method such as modifying a blend of polyethylene and an olefin rubber, modifying the polyethylene, then blending the olefin rubber, or modifying the olefin rubber and then blending the polyethylene. It is also possible to employ a method in which a modified polyethylene (masterbatch) having a high modifier concentration is prepared and then diluted with an appropriate unmodified resin. The graft ratio of the modifier of the modified polyethylene thus obtained is about 0.5 to 20% by weight, and 0.01 to 5
It has MI of about 0 g / 10 minutes.

In any of the modification methods, as a catalyst, a usual radical polymerization catalyst such as benzoyl peroxide, lauroyl peroxide, di-t-butyl peroxide, acetyl peroxide, t-butyl perbenzoate, or peroxybenzoate is used. Peroxides such as dicumyl oxide, perbenzoic acid, peracetic acid, t-butyl perpivalate, and 2,5-dimethyl-2,5-di-t-butylperoxyhexyne, and azobisisobutyronitrile. Azo compounds and the like can be used. The amount of the catalyst added is 0.005 to 0.3 parts by weight, preferably 100 parts by weight of the raw material resin.
0.01 to 0.05 parts by weight. It is also possible to add a phenol-based or phosphorus-based antioxidant during the above graft reaction.

Further, for the purpose of strengthening or modifying the modified polyethylene, other substances, for example, fillers and reinforcing materials such as glass fibers, heat stabilizers, light stabilizers, flame retardants, plasticizers, antistatic agents, foams. Agents, nucleating agents and the like can be added and blended.

As the polyethylene used for the laminate of the present invention, the same polyethylene as the modified raw material can be used. That is, high-pressure low-density polyethylene (HDPE), high-pressure low-density polyethylene (LLDPE), linear low-density polyethylene (LL) according to the application.
DPE) and the like can be used alone or in combination of two or more. Further, those modified with an unsaturated carboxylic acid or its anhydride can be blended and used.

Examples of the metal used in the laminate of the present invention include iron, aluminum, copper, zinc, nickel, tin, stainless steel, brass, tin plate and galvanized iron.
The polyethylene laminate of the present invention is basically a three-layer structure in which a modified polyethylene as an adhesive layer and a polyethylene as a surface layer are laminated on a metal substrate, but other thermoplastic resins such as polyester and nylon may be used as required. It can also be combined with. The method for producing the laminate is not particularly limited, and for example, modified polyethylene and a method of thermocompression bonding polyethylene in the form of a film or sheet, a method of laminating outside the die, a method of laminating (coextrusion) inside the die. A known method such as an extrusion coating method or a powder coating method can be adopted.

When laminating, the metal surface is usually preliminarily subjected to solvent degreasing, pickling, shot blasting, zinc phosphate treatment,
It is possible to obtain a laminate having a stronger adhesive force by subjecting it to pretreatment with calcium phosphate or the like, and further through a primer such as an epoxy resin as a primer treatment if necessary. As the epoxy resin-based primer, a one-component or two-component modified epoxy resin primer is preferable from the viewpoint of heat resistance or stability. The metal temperature during lamination is 120 to 250 ° C., preferably 160 to 20.
It is preferable to maintain the temperature at 0 ° C. and the resin temperature at 180 to 230 ° C. If the temperature of the metal is 120 ° C or lower, sufficient adhesive strength cannot be obtained, and if the temperature is 250 ° C or higher, sagging occurs,
It is not preferable because it may cause resin deterioration.

The coating resin layer of the laminate has a thickness of usually 1 to 5 mm, but the modified polyethylene adhesive layer needs to account for 10% or more of the resin layer thickness in order to obtain stable adhesion. Even if all of the coating resin layers are modified polyethylene, there is no problem in performance, but the cost increases. Therefore, it is usually preferable to have a multilayer structure in which unmodified polyethylene is laminated.

[0030]

In the laminate of the present invention, the polyethylene layer modified with polyethylene containing olefinic rubber in the adhesive layer has good affinity with the metal of the substrate and the polyethylene layer on the surface, and therefore has excellent adhesion, and the conventional MAH modified It is considered that it is excellent in hot water resistance and alkali resistance because it is modified with a modifying agent having an epoxy group that is less susceptible to invasion of water and alkali than the layer.

[0031]

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Production of Modified Polyethylene (Modified PE) (1) Production of Modified PE ~ Polyethylene (LLDPE [MI = 4 g / 10 min, density 0.93
4 g / cm ³ , stiffness 4600 kg / cm ² ]), olefin rubber (EBR [MI = 3.5 g / 10 min, density 0.88 g / cm ³ ,
Tensile modulus 200 kg / cm ² ]), as a modifier

[0033]

[Chemical 5] An unsaturated glycidyl compound (AXE [manufactured by Kanegafuchi Chemical Industry Co., Ltd.]) and a radical initiator (POX: Perhexin 25B [manufactured by NOF CORPORATION]] are dry blended in the proportions shown in Table 1. And twin-screw extruder (54mm
φ, L / D ratio 42) and screw rotation speed 150rp
The mixture was melt-kneaded at a temperature of 210 ° C. and pelletized. The MI of the obtained AXE-modified polyethylene is also shown in Table 1.

(2) Manufacture of modified PE The above was carried out except that glycidyl methacrylate (GMA [manufactured by Tokyo Chemical Industry Co., Ltd.]) was used instead of AXE as a modifier.
The same operation as in (1) was performed to obtain modified polyethylene.
The MI of the obtained GMA-modified polyethylene is shown in Table 1.

(3) Production of Modified PE Polyisobutylene (PIB [viscosity average molecular weight 990,000, density 0.9 g / c
m ³ ]) was used, and the same operation as in the above (1) was performed to obtain a modified polyethylene. The MI of the obtained AXE-modified polyethylene is shown in Table 1.

[0036]

[Table 1]

(4) Production of modified PE ~ Polyethylene (LLDPE [MI = 4 g / 10 min, density 0.93
4 g / cm ³ , stiffness 4600 kg / cm ² ]), polyolefin rubber (PIB), modifier (MAH: maleic anhydride) and radical initiator (POX) were dry blended in the proportions shown in Table 2 to give a uniaxial Type extruder (90mmφ, L /
Using a D ratio of 32), the mixture was melt-kneaded and pelletized at a screw rotation speed of 100 rpm and a temperature of 230 ° C. MAH obtained
The MI of modified polyethylene is also shown in Table 2.

[0038]

[Table 2]

Examples 1 to 6 and Comparative Examples 1 to 3 Using aluminum (Al) and a steel plate as metals, test pieces (laminates) were prepared. The manufacturing method is shown below. (1) Aluminum 0.1 mm thick aluminum and 0.1 mm thick modified polyethylene (modified PE ~) and 0.1 mm thick polyethylene (low pressure method high density polyethylene (HDPE): density 0.935)
g / cm ³ , MI (190 ° C, 2.16 kg load) 0.2 g / 10 min), aluminum / modified PE / HDPE / modified PE /
A 5-layer laminate of HDPE was prepared and cut into a width of 25 mm, which was used as a test piece.

(2) Steel plate Zinc phosphate treated steel plate (150 × 50 × 5.2 mm) and thickness of 0.1.
3mm modified polyethylene (modified PE ~) and thickness 0.7m
m polyethylene (low pressure method high density polyethylene (HDP
E): Using a density of 0.935 g / cm ³ and MI (190 ° C., 2.16 kg load) 0.2 g / 10 min), a three-layer laminate of steel plate / modified PE / HDPE was prepared, and the resin portion was cut into a width of 10 mm. After that, 20 mm from the end face was peeled off with a sharp blade to prepare a gripping margin, which was used as a test piece.

The adhesion strength of the above test piece was measured under the following conditions, and the results are also shown in Table 3. (a) Using an Intesco tensile tester, the 180 ° peel strength was measured at a measurement temperature of 23 ° C. and a pulling speed of 50 mm / min. (b) Hot water resistance test A laminate (aluminum) was immersed in hot water at 80 ° C and 100 ° C for 1 month, and the adhesion strength after that was measured according to the method of (a), and expressed as the strength retention rate (%). It was (c) Alkali resistance test 10% caustic soda aqueous solution (30 ° C) for the laminate (steel plate)
It was soaked in a sheet for 1 month, and the adhesion strength after that was measured according to the method of (a), and expressed as a retention rate (%) of the strength.

[0042]

[Table 3]

As is clear from Table 3, the laminates using MAH-modified polyethylene (Comparative Examples 1 to 3) had a strength retention rate of 80 to 100 ° C. under high temperature water conditions as compared with the initial adhesion strength. 60 to 70%, 5 under alkaline conditions
The strength was significantly reduced at 0%. On the other hand, in the laminates of the present invention (Examples 1 to 6), the strength of 90 to 99% was maintained as compared with the initial adhesion strength, and among them, polyethylene mixed with olefin rubber was modified with AXE. It can be seen that (Examples 1 to 3 and 6) show particularly excellent adhesion strength.

[0044]

As described in detail above, the polyethylene laminate of the present invention has a modified polyethylene adhesive layer obtained by modifying a resin composition prepared by mixing a metal substrate with an appropriate amount of olefin rubber into a metal substrate and modifying the resin composition with an unsaturated glycidyl compound. It is a laminate of polyethylene and is capable of improving the corrosion resistance and appearance of the metal, and particularly has good adhesion to the metal under hot water conditions and alkaline conditions. Such a polyethylene laminate of the present invention can be applied as a coating material for metal pipes, metal plates, electric wires, wires, etc., and is particularly required to have physical properties such as warm water resistance and alkali resistance in civil engineering and construction. It can be preferably used in the field.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Fujita 1-3-1 Nishitsurugaoka, Oi-cho, Iruma-gun, Saitama Tonen Research Institute

Claims (1)

[Claims] 1. A laminate of metal and polyethylene having an adhesive layer of a modified polyethylene composition obtained by modifying 100 parts by weight of polyethylene containing up to 50% by weight of an olefin rubber with 0.5 to 20 parts by weight of an unsaturated glycidyl compound.