JPS6353942B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in polyolefin and metal laminates. More specifically, the present invention relates to a metal laminate having excellent water resistance, which is formed by coating metal with a composition consisting of polyolefin and thermoplastic polyester. Attempts have been made to coat the inner and outer surfaces of metal tubes, the surfaces of metal plates, and the like with various polymeric substances for the purpose of preventing metal from rusting, improving the appearance, and improving food hygiene. Among them, polyolefin is suitable as such a material because it has various excellent physical and chemical properties, but since it is non-polar, it has no affinity with metals, so it cannot be heated and melted to adhere to metals. However, it easily peels off after cooling and solidifying, making it impractical as it is. For this reason, various techniques have been proposed to improve the adhesiveness between polyolefins and other vinyl monomers by modifying them or copolymerizing them with other vinyl monomers. As a representative example,
Examples of methods include using a polyolefin grafted with an unsaturated carboxylic acid such as maleic anhydride as an intermediate layer between the metal and the polyolefin, or using it instead of the polyolefin to ensure strong adhesion between the two (for example, Tokuko Akira
No. 39-6384, Special Publication No. 1973-23032, Special Publication No. 42-
10757 etc.). This method significantly improves the initial adhesive strength, but when it comes into contact with aqueous solutions containing electrolytic substances such as seawater or saline, or hot water, the adhesive strength decreases in a short period of time, resulting in peeling from the metal or impact. It has been discovered that when subjected to external force such as strength, it easily peels off. As a means of solving this problem, the present applicants have proposed a method in which an uncured epoxy resin adhesive is interposed between a polyolefin modified with an unsaturated carboxylic acid or its anhydride and a metal (Japanese Patent Publication No. 53-4880), or an unsaturated A method of interposing an organosilicon compound having a specific functional group between a polyolefin grafted with a carboxylic acid or its anhydride and a metal (Japanese Patent Publication No. 56-10184
No.) was proposed. However, although these methods improve adhesive strength and water resistance, in order to apply these methods, it is necessary to apply an epoxy resin adhesive or an organic silicon compound to the metal before bonding the modified polyolefin and the metal. For this reason, there were multiple processes, which caused problems in productivity and economy. Therefore, the present inventor was able to coat metal in one step,
Moreover, as a result of studying a laminate having excellent water resistance and adhesive strength, the present invention was achieved. That is, the present invention provides polyolefin (A) 98 to 2
The present invention provides a metal laminate coated with a polyolefin composition having excellent water resistance, characterized in that the metal body is coated with a composition comprising 2% to 98% by weight of thermoplastic polyester (B). . The metal bodies used in the present invention are metal bodies made of metals such as steel, stainless steel, iron, copper, lead, zinc, tin, aluminum, nickel, etc., or alloys of two or more thereof, such as plate-shaped bodies, pipes, etc. Including all shapes such as bodies, linear bodies, rod-shaped bodies, etc. The metal body is preferably one that has been subjected to treatments such as rust removal, degreasing, and pickling before being coated with the polyolefin composition described below, and may also be subjected to surface treatment such as chemical conversion treatment. The polyolefin (A) used in the present invention includes ethylene, propylene, 1-butene, 1-hexene, 1
- Homopolymers or mutual copolymers of α-olefins such as heptene, 4-methyl-1-pentene, 1-octene, 1-decene, etc., including crystalline and amorphous ones, generally low-density polyethylene ,
In addition to what is called medium density polyethylene, high density polyethylene, polypropylene, polybutene, ethylene/propylene random copolymer, ethylene/1-butene random copolymer, propylene/1-butene random copolymer, α-olefin and other Small amounts of copolymerizable monomers, such as vinyl acetate,
Ethylene/vinyl acetate copolymers, ethylene/acrylic acid copolymers, etc., which are copolymers with acrylic acid, etc., or unsaturated carboxylic acids such as maleic acid, acrylic acid, methacrylic acid, citraconic acid, itaconic acid, etc. It also includes those modified with its anhydride, its amide compound, its metal salt, etc. Among them, highly fluid polyethylene, ethylene/1-butene random copolymer, or modified products thereof are preferred in terms of impact resistance and processability. Also polyolefin
When mixing (A) with the thermoplastic polyester (B) described below to form a polyolefin composition, two or more of the above-mentioned polyolefins may be used. The thermoplastic polyester (B) used in the present invention is
ethylene glycol, propylene glycol,
Aliphatic glycols such as 1,4-butanediol, neopentyl glycol, polyoxyethylene glycol, and polyoxypropylene glycol, alicyclic glycols such as cyclohexanedimethanol, aromatic dihydroxy compounds such as bisphenol, or two or more of these Aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and 2,6-naphthalene dicarboxylic acid; and aliphatic dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, and undecadicarboxylic acid. A polyester formed from an acid, an alicyclic dicarboxylic acid such as hexahydroterephthalic acid, or a dicarboxylic acid unit selected from two or more of these, and as long as it exhibits thermoplasticity, a small amount of triol or tricarboxylic acid, etc. It may be modified with a trivalent or higher valent polyhydroxy compound, polycarboxylic acid, or the like. Further, the polyester may be crystalline or amorphous. Among these, polyethylene terephthalate, polybutylene terephthalate, and polyethylene isophthalate-terephthalate copolymer are more preferred in terms of heat resistance, processability, and manufacturing cost. The polyolefin composition used for coating a metal body of the present invention is a mixture of the polyolefin (A) and thermoplastic polyester (B) in a ratio of 98/2 to 2/98, preferably
It is a mixture in the range of 95/5 to 5/95 (all percentages by weight). If the polyolefin (A) is less than 2% by weight, the adhesive strength and water resistance of the coating material will not be improved, and if the thermoplastic polyester (B) is less than 2% by weight, practical initial adhesive strength cannot be obtained. The polyolefin composition includes the polyolefin (A)
and thermoplastic polyester (B) are calculated within the above range, and mixed directly with a ribbon blender, V-blender, tumbler blender, Henschel mixer, etc., or further mixed with a single screw extruder, double screw extruder, kneader, Banbury. It is obtained by kneading and mixing using a mixer or the like and then granulating. Additives such as pigments, dyes, fillers, reinforcing agents, heat stabilizers, ultraviolet absorbers, lubricants, flame retardants, antistatic agents, and other polymers may be added to the polyolefin composition without impairing the purpose of the present invention. It may be added within a certain range. The polyolefin composition-coated metal laminate of the present invention can be obtained by various known methods. For example, a method of preheating a metal body and extrusion coating with a polyolefin composition, a method of injection molding a polyolefin composition onto a preheated metal body, or a method of coating a powdered polyolefin composition on a metal body and bonding by heating. Alternatively, the metal body and a sheet or film of the polyolefin composition may be superimposed and bonded by heating. The thickness of the polyolefin composition coating layer is adjusted appropriately depending on the use of the metal laminate, but usually
A metal laminate with excellent coating performance can be obtained by coating with a thickness of 500 μm or more, preferably 1 mm or more. The polyolefin composition-coated metal laminate of the present invention has superior adhesive strength compared to conventional unmodified polyolefin-coated metal laminates, and has superior adhesive strength and water resistance compared to laminates having a coating layer of modified polyolefin or thermoplastic polyester. Therefore, products obtained by extrusion such as submarine buried steel pipes, natural gas pipelines, industrial coated steel pipes, and aquaculture wire mesh for fisheries, etc.
In addition, the laminate of the present invention is suitable for use in injection molding, such as step fittings for sewer manholes, and since the laminate of the present invention can obtain a coated metal laminate in one step, an epoxy adhesive or an organic silicon compound can be used as an adhesive. It has the advantage that the process is simpler than the laminate used as a laminate. Next, the present invention will be explained in more detail with reference to Examples. Examples 1 to 8, Comparative Examples 1 to 6 A steel pipe with a diameter of 25 mm whose surface was sandblasted was passed through an electric furnace to preheat the surface temperature to 200°C, and then a medium-density polyethylene was used as a coating layer: Product name: Neo-Zex 2540R (Mitsui) Petrochemical industry KK
), ethylene/α-olefin copolymer: trade name TAFMER A-4085 (Mitsui Petrochemical Industries KK)
), modified polyolefin: Product name Admer
NE050 (manufactured by Mitsui Petrochemical Industries KK) and polyethylene terephthalate: Product name TENITE
A polyolefin composition prepared by mixing Polyester 7352 (manufactured by Eastman Chemical Products Co., USA) in the proportions shown in Table 1 was heated and melted in an extruder, and then passed through a crosshead die (set temperature: 270°C) into the steel pipe with a 2 mm diameter. After coating to a certain thickness, cold water was poured to quench it to obtain a polyolefin composition coated steel pipe. Next, the coated steel pipe was immersed in hot water at 80° C. for 5 days to conduct a water resistance test for adhesive strength. Table 1 shows the initial adhesive strength and the adhesive strength after the water resistance test. 【table】

Claims (1)

[Claims] 1. A metal laminate coated with a polyolefin composition, comprising a metal body coated with a composition comprising 98 to 2% by weight of polyolefin (A) and 2 to 98% by weight of thermoplastic polyester (B).