JPH0485025A - Laminate of metal using epoxy-modified polyolefine - Google Patents

Abstract

PURPOSE:To obtain a laminate which is excellent in adhesive properties and flexibility between the respective layers by providing the layer of a mixture of both the phenolic resin initial condensate and specified nitrile rubber on the surface of metal and providing a polyolefine layer having epoxy group and a polyolefine layer thereon and bonding them. CONSTITUTION:A steel sheet is degreased by toluene. Then both resol type phenolic resin oligomer as phenolic resin initial condensate and nitrile rubber having carboxyl group or amino group in both terminals of a molecular chain are dissolved in methyl ethyl ketone being a common solvent thereof and mixed. The said steel sheet is coated with this primer soln. by brushing and one part of the solvent is volatilized. Then curing is promoted in a hot air dryer and immediately ethylene-glycidyl methacrylate binary copolymer as polyolefine having epoxy group is pressure-formed on the above-mentioned primer. Furthermore low density polyethylene is pressure-formed thereon. This pressure-formed material is inserted into the hot air dryer. Curing of the primer composition and melting of the interlayer and the overcoated layer are promoted. A laminate is obtained by taking out the pressure-formed material from the dryer.

Description

Detailed Description of the Invention (Industrial Application Field) This invention relates to a laminate in which metal/primer layer/intermediate layer/overcoat layer are firmly adhered to each other. Specifically, the present invention relates to a laminate that has not only the above-mentioned adhesive strength but also excellent water resistance, heat resistance, and flexibility, and also has the function of relaxing and dispersing stress acting on the adhesive interface between the metal and the primer layer.

(Prior art) A metal laminate using a thermoplastic resin as a primer layer or an intermediate layer is disclosed in Japanese Patent Publication No. 59-30547 and Japanese Patent Publication No. 59-30547.
No. 4-42393 and Japanese Patent Publication No. 10310/1983. However, in all of the materials described in these publications, the adhesive force between the primer layer or intermediate layer and the polyolefin is weak, and the primer layer or intermediate layer has poor water resistance. Further, a metal laminate using a thermosetting resin as a primer layer is described in Japanese Patent Publication No. 57-26622. However, the method described in this publication cannot relieve and disperse the stress acting on the adhesive interface between metal and resin. The adhesion between the primer layer or intermediate layer and polyolefin is weak.

(Problems to be Solved by the Invention) This invention provides strong adhesion between the gold It/primer layer/intermediate N/overcoat layer, and also has water resistance, heat resistance,
The object of the present invention is to provide a laminated wood that has excellent flexibility and also has the function of relaxing and dispersing stress acting on the adhesive interface between the metal and the primer layer.

(Means for solving the problem) This invention uses polyolefin for the overcoat layer, uses the same type of polyolefin as the overfoot layer having an intramolecular silicone epoxy group for the intermediate layer, and uses 1) phenol for the primer layer. Resin oligomer (b) uses nitrile rubber that is solid at room temperature and has a carboxyl group or an amino group in its molecule, and uses metal as the adherend.

The polyolefin used as the overcoat layer includes:
Polyethylene (hereinafter abbreviated as PE), polypropylene (
(hereinafter abbreviated as PP). The performance of the laminated wood is the key objective; it is necessary to select the resin and grade accordingly. P.E.

The properties of both PP vary slightly depending on crystallinity, molecular weight, chemical structure, etc., but both are general-purpose resins, are easy to mold, and have excellent chemical and water resistance. Therefore, it is ideal as an overcoat layer resin for lining pipes and tanks, or for coating laminates.

The overcoat layer may contain an inorganic filler if necessary. Inorganic fillers include metals, metal acids and arsenics,
Glass, carbon, ceramics, etc. can be used. As the metal, aluminum, zinc, nickel alloy, stainless steel, iron alloy, etc. can be used. As the metal oxide, alumina, iron oxide, titanium oxide, zirconium oxide, acid f-hyfurome, nickel oxide, talc, potassium titanate, etc. can be used. As ceramics, in addition to those included in metal oxides, silicon nitride, titanium nitride, boron carbide, and silicon carbide can be used.

The intermediate layer uses the same type of polyolefin as the overcoat layer, which has an epoxy group in its molecule.

In other words, when using PE for the overcoat layer,
Using PE having an epoxy group in the molecule as the intermediate layer,
When PP is used for the overcoat layer, PP having an epoxy group in the molecule is used as the intermediate layer. This is to improve the adhesive force between the overcoat layer and the intermediate layer, and because when the same type of resin is used, both resins have good compatibility and a large intermolecular force acts.

Furthermore, for this reason, it is preferable to use molecules with similar molecular weights and chemical structures. If a polyolefin having an epoxy group in the molecule that satisfies the above conditions is used as the intermediate layer, the overcoat layer and the intermediate layer will be firmly adhered to each other.

In order to firmly adhere the intermediate layer and the primer layer, the resin used as the intermediate layer must have an epoxy group in its molecule. Polyolefins having epoxy groups in their molecules are commercially available. For example, it is a binary copolymer of glycidyl methacrylate (glycidyl ester of methacrylic acid) and an olefin (hereinafter referred to as olefin-
These are glycidyl methacrylate copolymers) and terpolymers of glycidyl methacrylate, vinyl acetate, and olefins (hereinafter referred to as olefin-vinyl acetate-glycidyl methacrylate copolymers).

The above-mentioned binary and ternary copolymers have significantly different properties due to the difference in the content of glycidyl methacrylate and vinyl acetate. Generally, as the content of glycidyl methacrylate and vinyl acetate increases, it becomes softer and exhibits elastomer-like elongation and elasticity. Usually, a vinyl acetate content of 0-40% is used.

This is because vinyl acetate does not participate in adhesion with the primer layer, which is one of the purposes of the intermediate layer.
Although it may be present or absent, if its content exceeds 40%, the rigidity, heat resistance, and water resistance of the intermediate layer will not be sufficiently satisfied. On the other hand, the content of glycidyl methacrylate is preferably 5-30%. This uses the epoxy group in the glycidyl methacrylate to firmly adhere to the primer layer.
This is because if the content of glycidyl methacrylate is less than 5%, strong adhesion cannot be obtained. Also,
This is because if the content exceeds 30%, the rigidity, heat resistance, and water resistance of the intermediate layer will not be satisfied, as in the case of vinyl acetate.

Instead of using the copolymer of ethylene and glycidyl methacrylate as described above, it is also possible to graft a polyolefin by reacting the vinyl group in glycidyl methacrylate CH300. - As an example, a method of grafting PE by reacting the above-mentioned glycidyl methacrylate monomer will be described below.

First, glycidyl methacrylate is dissolved in benzene to make a 5% by weight solution, and PE is added to this solution. This is repeatedly frozen and thawed using liquid nitrogen, degassed and sealed at a pressure of 1.01 μm, and grafted by irradiation with Co60 gamma rays.

In this way, when grafting a polyolefin by reacting it with glycidyl methacrylate, it is said that a grafting rate of 10 to 80% is suitable. As in the case of the copolymer described above, in order to firmly adhere the intermediate layer and primer layer using the epoxy groups in the grafted material, a grafting ratio of 10% or less is insufficient for adhesion. On the other hand, if the grafting rate is 80% or more, the water resistance and heat resistance of the polyolefin itself will be lost.

The intermediate tube may contain an inorganic filler if necessary. Inorganic fillers that can be included in the intermediate layer include:
This is the same inorganic filler that can be included in the overcoat layer described above. That is, metals, metal oxides, glass, carbon, ceramics, etc. can be contained.

The primer layer contains a) ferro resin oligomer, b
) A composition made of nitrile rubber that has a carboxyl group or an amine 7 group in its molecule and is solid at room temperature is used.

Phenolic resins include resol type and novolac type. The resol type is cured alone, and the novolak type is cured by adding a curing catalyst such as hexamethylenetetramine and heating together, resulting in an insoluble and infusible product with a three-dimensional network structure. In this invention, either can be used.

Phenol resin is an extremely polar substance that bonds to the oxide film on the metal surface through chemical bonds or intermolecular forces, and firmly adheres to the metal.

Furthermore, since the phenol resin has a three-dimensional network structure, it has excellent water resistance and heat resistance. Therefore, even if the laminate of the present invention is used in an environment where it is immersed in hot water and the hot water penetrates and diffuses into the overcoat layer and intermediate layer, the metal surface is completely protected by the phenolic resin. This prevents the occurrence of molding on the metal and a decrease in the adhesion to the brimer.

Nitrile rubber is a copolymer of acrylonitrile and butadiene, and its properties vary widely depending on the acrylonitrile content. As the content of acrylonitrile increases, cohesive strength and oil resistance increase, but on the other hand, cold resistance decreases. Usually the acrylonitrile content is 3
Use 0-45%.

The polarity of nitrile rubber is one of the properties that is related to the compatibility between nitrile rubber and phenolic resin and the adhesion to metals. When compared to other rubbers used for adhesives, the polarity decreases in the order of nitrile rubber, chloroprene rubber, styrene-butadiene rubber, natural rubber, and butyl rubber, with nitrile rubber having the highest polarity. This is due to the nitrile group of acrylonitrile contained within the molecule. As described above, since nitrile rubber has higher polarity than other rubbers, it is well compatible with polar substances such as phenolic resins, and also exhibits strong adhesion to metals.

It is known that nitrile rubber chemically reacts with phenolic resin* phenolic resin oligomers. Although the reaction mechanism is not yet clear, it is said that the double bond and nitrile group in the nitrile rubber react with the 72/-l resin or phenolic resin oligomer. In this way, the double bonds in the nitrile rubber are consumed by directly reacting with the phenol resin, etc., so there is no need to crosslink the nitrile rubber in advance with a vulcanizing agent or metal oxide.

In this way, by including nitrile rubber in the primer layer, the primer layer not only has excellent adhesion to metal but also has excellent flexibility and elasticity, which are the inherent properties of elastomers. Therefore, the stress acting on the adhesive interface between the metal and the primer layer is relaxed and dispersed, and peeling, blistering, and cracking caused by the stress are prevented.
This results in long-term durability.

In order to firmly bond the product of phenolic resin oligomer and nitrile rubber as a primer layer, and the same type of polyolefin as the overcoat layer having an epoxy group in the molecule as an intermediate layer, nitrile rubber has a ) It is necessary to have this carboxy/+4 or ami7 group. Polyolefins having epoxy groups directly react with compounds having carboxyl or amine groups to form chemical bonds. Therefore, this chemical bond causes the primer layer and the intermediate layer to be firmly adhered to each other.

As an example, the reaction pattern between a nitrile rubber having cynical carboxyl groups at both terminal ends of its molecular chain and PE grafted with a glycidyl methacrylate monomer is shown below.

This carboxyl group or amide 7 group may be located either at the end of the molecular chain of the nitrile rubber or in the middle of the molecular chain. The number of carboxyl groups or amino groups is preferably two or more on average per molecule of nitrile rubber. This is a necessary condition for the carboxyl group or amino group introduced into the nitrile rubber to react with the polyolefin having an epoxy group in the molecule, and for the primer layer and the intermediate layer to firmly adhere to each other. .

The amount of nitrile rubber added having a carboxyl group or amino group in the molecule is preferably 25 to 250 parts by weight per 100 parts by weight of the phenolic resin oligomer.The reason is that the amount of nitrile rubber added is 25 parts by weight. If the amount of nitrile rubber added is less than If the amount is more than 250 parts by weight, the properties of the phenol resin will be lost, and heat resistance, water resistance, rigidity, etc. will be reduced.

The primer layer may contain an inorganic filler if necessary. Oxides, etc.

In order to uniformly mix phenolic resin oligomer and nitrile rubber, which is solid at room temperature and has a carboxyl group or amino group in the molecule, and apply the mixture onto metal, a common solvent for the phenol resin oligomer and nitrile rubber is required. Common solvents include methyl ethyl ketone. The amount added varies depending on the method of applying the primer solution to the metal surface.For example, when applying by brushing, the amount added is 0.3- It is preferable to add 25 parts by weight of solvent, because if the amount of solvent added is less than 0.3 parts by weight, the viscosity of the primer solution will be too high and uniform application will be difficult. On the other hand, 25
This is because if the amount is more than 1 part by weight, the viscosity of the primer solution becomes too low, causing problems such as sagging.

Finally, a method for manufacturing a laminate according to the present invention will be explained. First, the metal used in the laminate is degreased in advance using an alkaline solution or an organic solvent, etc. Then, a) phenolic resin oligomer b) Nitrile rubber that is liquid at room temperature and has a carboxyl group or an amino group in the molecule. Take an appropriate amount of , dissolve and mix in a common solvent such as methyl ethyl ketone. When the phenolic resin oligomer is a novolac type, hexamethylenetetramine or the like is further added as a curing agent.Then, this solution is applied onto the metal.

The primer solution can be applied using any method depending on the viscosity of the solution, the material and surface roughness of the adherend metal, etc.For example, a spatula, brush, brush, hand roller, roller with tank, roll coater, etc. Select and use the appropriate one from among flow guns, float brushes, spray guns, etc.

Most of the solvent in the primer solution applied to the metal is evaporated by air drying or by using a blower or vacuum dryer.

As a result, the solvent does not need to be completely volatilized.

This is because the solvent is allowed to volatilize during curing of the primer composition. This is then heated above the curing temperature of the phenolic resin to cure the primer composition on the metal. It is preferable to line or coat the intermediate layer with a polyolefin containing epoxy groups in the molecule before the curing reaction is completely completed. As a result, there is a state where the adhesive strength is maximum, and then as the curing reaction progresses, the adhesive strength decreases. Therefore, lining or coating is attempted in a state where the adhesive strength is maximum. Finally, an overcoat layer of polyolefin is lined or coated on the intermediate layer to complete the laminate according to the present invention. Note that the intermediate layer and the overcoat layer may be co-pressed.

The laminate thus manufactured has four layers, a metal layer, a primer layer, an intermediate layer, and an overcoat layer, laminated in this order.

The laminate according to the present invention can be applied to a very wide range of applications, such as for lining and coating pipes and tanks that require water resistance, chemical resistance, and heat resistance.

(Effects of the Invention) The laminate of the present invention includes a polyolefin in the overcoat layer, a polyolefin of the same type as the overcoat layer having an epoxy group in the molecule in the intermediate layer, and a) phenolic resin oligomer b) in the molecule in the primer layer. Because the composition is made from nitrile rubber that is solid at room temperature and has epoxy or amino groups, and metal is used for the adherend, it has excellent adhesion between each layer, water resistance, heat resistance, and flexibility. It has the ability to relax and disperse stress acting on the adhesive interface between the primer layer and the primer layer. In this respect, the invention provides significant benefits.

(Example) Next, Examples and Comparative Examples of this invention will be given to clarify the effects of this invention more specifically.

At that time, the adhesive force between the overcoat layer or intermediate layer and the primer layer is expressed by the results of a 90' peel test at 25°C and a peel rate of 50 Wm/min, and the adhesive force between the primer layer and the metal One guideline for the adhesive strength between the two was the result of the braimer cross-cut test. In addition, in order to evaluate the performance of the laminate as a whole, such as heat resistance, water resistance, stress relaxation acting on the interface between the primer layer and the metal, and the degree of dispersion, the overcoat layer side was heated with 60°C hot water. immerse the metal side in 40℃ warm water,
A temperature gradient test was performed.

Example 1 First, a 100m×100m×3aun steel plate was degreased with toluene for 10 minutes using an ultrasonic cleaner.Then, a resol type phenolic resin oligomer (
Manufactured by Sumitomo Bakelite Co., Ltd., Sumilite resin, Pl? -5
0232) 100 parts by weight of nitrile rubber that is solid at room temperature and has carboxyl groups at both ends of the molecular chain (manufactured by Japan Synthetic Rubber Co., Ltd., PNC-25, carboxylic acid equivalent 900) 1
00 parts by weight was dissolved and mixed in 1500 parts by weight of methyl ethyl ketone, which is a common solvent for both.Next, this brimer solution was applied with a brush onto the steel plate and left at room temperature for about 10 minutes to remove the solvent in the solution. A portion of the brimer composition was volatilized and then placed in a hot air dryer at 180°C to accelerate curing of the brimer composition, and after 5 minutes it was taken out from the hot air dryer. Immediately add ethylene-glycidyl methacrylate binary copolymer (Sumitomo Chemical Co., Ltd., Bondfast E),
Press molding was carried out on the above brimer at 150"C for 5 minutes. Furthermore, on top of this, low density polyethylene (manufactured by Asahi Kasei Co., Ltd., LM7625, melting point 128 °C, MI = 20) was applied at 150"C.
Press molding for 10 minutes at 140°C and finally at 140°C.
was placed in a hot air dryer to promote curing of the brimer composition and melting of the intermediate layer and overcoat layer, and removed after 20 minutes.

In the thus obtained laminate, the primer layer had a thickness of 42 days and the intermediate layer had a thickness of 1! i! The thickness was 420 ttm, and the thickness of the overcoat layer was 530 μm. The peel test results were obtained by pulling PE and ethylene-glycidyl methacrylate copolymer.

The 90° peel strength was 13.1 kg/cm, and the results of the temperature gradient test showed that blistering occurred in 20 days.

Example 2 The ethylene-glycidyl methacrylate copolymer of the intermediate layer was replaced with an ethylene-vinyl acetate-glycidyl methacrylate terpolymer (manufactured by Sumitomo Chemical Co., Ltd., Bondfast
It is the same as Example 1 except that A) was changed. The thickness of the brimer is 40μm, and the thickness of the intermediate layer is 410μm.
The thickness of the overcoat layer was 520 μm.

In addition, the peel test results were obtained by pulling the overcoat layer and the intermediate layer.

The 90° peel strength was 14.3 kg/am, and the results of the temperature gradient test showed that blistering occurred in 15 days.

Example 3 The ethylene-glycidyl methacrylate binary copolymer of the intermediate layer was replaced with a propylene-glycidyl methacrylate binary copolymer (manufactured by Sumitomo Chemical Co., Ltd., Bondfast [;)
The pressing temperature when laminating the intermediate layer was changed from 180°C to 200°C, and the overcoat layer was changed from PE to PP (manufactured by Sumitomo Chemical Co., Ltd., Sumitomo Norfren Y101, melting point 160"
C, M+ = 12), the press temperature when laminating the overcoat layer was changed from 150"cxs minutes to 200°C x 10 minutes, and the temperature of the final hot air dryer was changed from 140°C to 230°C.
The process is the same as Example 1 except that it is changed to “C”.The thickness of the primer is 39μm, and the thickness of the intermediate layer is 410μm.
The thickness of the overcoat layer was 505 μm. In addition, in the peel test, the test results were obtained by pulling the overcord layer and the intermediate layer.

The 90° peel strength was 12.8 kg/c11, and the temperature gradient test showed that blistering occurred in 18 days.

Comparative Example 1 The same as Example 1 except that the ethylene-glycidyl methacrylate copolymer of the intermediate layer was not laminated.

The thickness of the primer was 38 μm, and the thickness of the overcoat layer was 510 μm. In addition, in the peel test, the overcoat layer was pulled and the test results were obtained.

The 90° peel strength was Okg/a++, and the results of the temperature gradient test showed that blistering occurred in 2 days.

Comparative Example 2 Same as Example 1 except that nitrile rubber in the primer component was not added. The thickness of the primer was 41 μm, the thickness of the intermediate layer was 450 μm, and the thickness of the overcoat layer was 490 μm. In addition, the peel test results were obtained by pulling the overcoat layer and the intermediate layer.

The 90° peel strength was 1.2 kg/am, and the results of the temperature gradient test showed that blistering occurred in 3 days.

Comparative Example 3 The same as Example 1 except that the phenolic resin oligomer in the primer component was not added and 2 parts by weight of sulfur powder was added as a vulcanizing agent for nitrile rubber. The thickness of the primer is 32 μm, the thickness of the intermediate layer is 450 μm,
The thickness of the overcoat layer was 570 μm. Also,
The peel test was performed by pulling the overcoat layer and the intermediate layer.

The 90° peel strength was 3.1 kg/cm, and the results of the temperature gradient test showed that blistering occurred in 2 days.

Claims (1)

[Claims] A layer of a mixture of a phenolic resin initial condensate and a nitrile rubber having a carboxyl group or an amino group in the molecule is provided on the metal surface, a polyolefin layer having an epoxy group is provided on top of that, and a layer of a polyolefin having an epoxy group is provided on top of the mixture. A polyolefin layer is provided and the polyolefin is adhered to the metal.
A metal laminate using epoxy-modified polyolefin.