JPH029935B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to extrusion coated thermoplastic polyester multilayer coated metal laminates. More specifically, the present invention relates to a thermoplastic polyester multilayer-coated metal laminate formed by extrusion coating and having excellent adhesion to a metal body, which is formed by coating two or more types of thermoplastic polyesters having different flow initiation temperatures.

Conventionally, thermoplastic resins such as polyethylene and vinyl chloride have been extruded and coated on metal bodies to prevent corrosion, but these resins have weak coatings and are susceptible to shock during transportation and storage. Another problem is that the coating is easily damaged during bending, caulking, connection, and other operations. As one of the means to solve these problems, a metal body coated by extrusion with a polyethylene terephthalate polymer having a crystallinity of 20% or less (Japanese Patent Application Laid-open No. 17988/1982),
A method of extrusion coating a polymethylene terephthalate polymer on a metal body heated to 200 to 350℃ (Japanese Patent Application Laid-open No.
51-148755), a technique of extrusion coating a polyethylene terephthalate polymer or a polymethylene terephthalate polymer has been proposed. However, according to these proposals, in order to obtain strong adhesion, the metal body must be heated to at least 200°C.
As mentioned above, it is necessary to heat the metal body preferably to 240°C, and in practice, heating the metal body to a high temperature of 200°C or higher requires a large amount of equipment. Therefore, the present inventors investigated a method for obtaining a thermoplastic polyester-coated metal laminate by extrusion coating with strong adhesive strength without preheating the metal body to a high temperature. If a thermoplastic polyester with a low flow start temperature is used as the adhesive layer with the metal body, it is possible to create a metal laminate that does not require preheating the metal body to a high temperature and has superior adhesive strength than a single-layer thermoplastic polyester coating. It has been found that the present invention can be obtained.

That is, the present invention provides a thermoplastic polyester-coated metal laminate in which thermoplastic polyester (),
Furthermore, the upper layer is made of thermoplastic polyester ()
The object of the present invention is to provide a thermoplastic polyester multilayer coated metal laminate, characterized in that it is made by laminating thermoplastic polyester () having a flow initiation temperature higher than 30°C by extrusion coating.

The metal bodies used in the present invention include metal bodies such as steel, stainless steel, copper, lead, zinc, aluminum, and nickel, and include all shapes such as plates, tubes, wires, and rods. include. The metal body is preferably subjected to treatments such as rust removal, degreasing, and pickling before being coated with the thermoplastic polyester described below, and may also be subjected to surface treatment such as chemical conversion treatment.

The thermoplastic polyester used in the present invention includes ethylene glycol, propylene glycol, 1,
4-butanediol, neopentyl glycol,
Aliphatic glycols such as polyoxyethylene glycol and polyoxypropylene glycol, alicyclic glycols such as cyclohexanedimethanol, aromatic dihydroxy compounds such as bisphenol, or dihydroxy compound units selected from two or more of these, and terephthalic acid. , isophthalic acid,
Aromatic dicarboxylic acids such as 2,6-naphthalene dicarboxylic acid, aliphatic dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, undecadicarboxylic acid, alicyclic dicarboxylic acids such as hexahydroterephthalic acid, or these A polyester formed from dicarboxylic acid units selected from two or more of You can leave it there. Further, the polyester may be crystalline or amorphous.

In the present invention, the flow start temperature refers to the temperature at which a sample starts to flow when the sample is heated, and approximately 10 mg of the sample is The sample was heated at a temperature increase rate of 1° C./min, and the temperature at which the sample started flowing was read, and this temperature was taken as the flow starting temperature.

The thermoplastic polyester-coated metal laminate of the present invention consists of two or more thermoplastic polyesters having different flow start temperatures measured by the method described above, such that the thermoplastic polyester () with a lower flow start temperature is brought into contact with the metal body. This is a metal laminate made by laminating a high thermoplastic polyester (2) on top of a thermoplastic polyester (2) by extrusion coating. Thermoplastic polyester used for adhesive layer with metal objects ()
and thermoplastic polyester used for its upper layer ()
The purpose of the present invention is achieved if the flow start temperature of the thermoplastic polyester () is 30°C or more lower than that of (), but preferably 100°C.
It is preferable to select a thermoplastic polyester having the above temperature difference because the preheating temperature of the metal body when coating the thermoplastic polyester can be lowered. Further, it is preferable to use a crystalline polyester with a hard surface hardness as the thermoplastic polyester () used for the upper layer because the coating is less likely to be damaged. From this viewpoint, examples of preferred combinations of polyester () and polyester () include polyethylene isophthalate as polyester (), and polyethylene terephthalate as polyester ().

The thermoplastic polyester multilayer-coated metal laminate of the present invention can be obtained by successively extrusion coating the above polyesters () and () while heating a metal body to a surface temperature of less than 200°C. It can be obtained by extrusion coating method. For example, a method in which a metal body is preheated, a thermoplastic polyester (2) with a low flow start temperature is extruded and coated on the metal body, and then a thermoplastic polyester (2) with a high flow start temperature is extruded and coated on the upper layer of (2), and the preheated metal Examples include a method of simultaneously extruding and coating the thermoplastic polyester (2) and the thermoplastic polyester (2) on the body so that the thermoplastic polyester (2) is in contact with the metal body.

The thickness of the thermoplastic polyester coating layer is adjusted appropriately depending on the use of the metal laminate, but usually the thickness of the adhesive layer and the upper layer is 100μ or more, preferably 1
When coated with a thickness of mm or more, a metal laminate with excellent coating performance can be obtained.

The thermoplastic polyester used in the present invention contains additives such as pigments, dyes, fillers, reinforcing materials, heat stabilizers, ultraviolet absorbers, lubricants, flame retardants, antistatic agents, and other polymers. may be added as long as it does not impair it.

The thermoplastic polyester multilayer coated metal laminate by extrusion coating of the present invention can be obtained at a lower temperature than conventional polyethylene terephthalate-based extrusion coated metal bodies, and moreover, it is possible to heat-press the single-layer extrusion coated body and the laminated film. Since the adhesive strength is stronger than that of laminates, it can be widely used for corrosion protection of steel pipes and steel wires, industrial parts, electrical appliance parts, etc.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 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 180°C, and then polybutylene terephthalate with a flow start temperature of 229°C was heated and melted using one extruder. Polyethylene terephthalate with a flow start temperature of 268°C is heated and melted in one extruder, and polybutylene terephthalate is co-extruded from a two-layer crosshead die (set temperature: 280°C) so that it is in contact with the steel pipe to form each coating. After coating a steel pipe with the film to a thickness of 0.5 mm, cold water was poured to quench it to obtain a thermoplastic polyester double-coated steel pipe. The peel strength of the obtained film was 15Kg/cm
It was hot.

Example 2 The same procedure as in Example 1 was carried out, except that the preheating temperature of the steel pipe was 150°C, and polyethylene isophthalate with a flow start temperature of 110°C was used as the thermoplastic polyester in the layer in contact with the metal. The peel strength of the coating on the obtained coated steel pipe was 21 kg/cm.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the polyethylene terephthalate used in Example 1 was used for both the adhesive layer and the upper layer. The coating on the obtained coated steel pipe did not adhere at all and was easily peeled off.

Comparative Example 2 The same procedure as in Example 1 was carried out except that the polybutylene terephthalate used in Example 1 was used for both the adhesive layer and the upper layer. The peel strength of the coating on the obtained coated steel pipe was 7 kg/cm, which was a weak adhesive force.

Claims (1)

[Claims] 1 Thermoplastic polyester () on a metal body preheated to a surface temperature of less than 200°C, and a thermoplastic polyester (2) having a flow start temperature 30°C or more higher than the thermoplastic polyester (2) as an upper layer.
A thermoplastic polyester multilayer coated metal laminate, characterized in that it is made by laminating by extrusion coating.