JPS5938268A - Bonding process of polyolefin resin - Google Patents

Abstract

PURPOSE:To effect firm bonding, by surface-treating the adherend surface of polyolefin resin molding to attain the wetting tension of the surface in a specific range by irradiating with a low-temp. plasma, and causing to adhere to coated metals using a one-component urethane sealant. CONSTITUTION:Gases such as oxygen, nitrogen, or argon at a pressure of about 10mm.Hg or lower are excited by discharge such as glow discharge or high-frequency discharge to produce a low-temp. plasma. The adherend surface of molding of polyolefin resin such as ehtylene/propylene copolymer is irradiated with said low-temp. plasma and surface-treated to attain the wetting tension of the adherend surface of 88-65dyne/cm<2>. Then said surface is firmly bonded with the surface of coated metals by the use of a one-component urethane sealant as an adhesive. Commercially available one-component urethane sealants include ''Betaseal 551'' (Sunstar Chemical KK).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for firmly adhering a polyolefin resin to a painted metal surface. Until now, polyolefin resin has a non-polar chemical structure and extremely low surface tension, making surface adhesion with dissimilar materials almost impossible, so it has been used in fields that require secondary processing such as adhesion and painting. It is extremely rare for this to occur. On the other hand,
Among polyolefin resins, demand for polypropylene resins in automobile parts and light electrical parts is increasing due to their mechanical properties, heat resistance, economic efficiency, etc., and some are also making inroads into fields that require adhesive properties. For example, the side protector, which is an exterior part of your IIJ car, is one such example.

Until now, side protectors have been made of thermoplastic polyester elastomer or soft vinyl chloride resin due to their adhesive properties, such as silicone sealant or urethane sealant, but polypropylene has been used due to cost, decrease in adhesive strength over time, and weight reduction. Conversion to resin is being considered. In this case, the problem is the adhesion between the polypropylene resin and the adhesive. Use of brimer as a means to improve the adhesion between polypropylene resin and adhesive.
Our researchers conducted various studies on the use of modified polyolefin as an adhesive layer and the surface treatment of polypropylene resin, and to our surprise, we found that by low-temperature plasma treatment of the surface of polypropylene resin molded products, it could be strongly bonded to the urethane sealant. The present invention was achieved by discovering that it can be bonded. In the present invention, low-temperature plasma treatment refers to a pressure of preferably 10 ywHf or less, preferably 0.1 to 1.0 mt.
A molded product obtained by exciting a gaseous body such as IIf oxygen, nitrogen, argon, helium, etc., preferably oxygen, by discharge such as glow discharge or high-frequency discharge to generate low-temperature plasma, and molding a polyolefin resin in this atmosphere. This is a method in which the plasma treatment is carried out by placing
is necessary, and if it is less than that, the effect of the treatment on adhesion will not be significant. Furthermore, if the treatment is too strong, the surface of the polypropylene resin tends to decompose, leading to a decrease in adhesive strength. For this reason, it is desirable that the surface wetting tension of the surface to be treated be between 38 dynes/d and 65 dynes/C-, and more preferably between 42 and 65 dynes/C-. .

The polyolefin resin composition in the present invention is ethylene-
It is a single or mixed composition mainly composed of a propylene copolymer or an ethylene propylene copolymer, and may be mixed with an inorganic filler such as calcium carbonate or talc or an organic filler such as process oil. It is also possible.

The adhesive used in the present invention is a one-component urethane sealant that hardens at II, 0 in air, and a commercially available product is Betaseal 551 (Sunstar Chemical). Examples are shown below.

Example 1 Sumitomo Noblen AD 571 (MIo, 6, brobylene-ethylene block cobocumer) was extruded to 5y.
A test piece of tmpp was prepared and adhered to a metal plate coated with Lure 551 (Sunstar Chemical) on the surface of the test piece using a high-frequency low-temperature plasma generator.
The strength was measured by shear peeling after aging.

Comparative Example 1 The same test as in Example 1 was conducted, except that the surface wetting tension immediately after the low-temperature plasma treatment was adjusted to 82 to 85 dynes/C-.

Comparative Example 2 Surface wetting tension immediately after low temperature plasma treatment is 70 dynes/c
The same test as in Example 1 was conducted except that the material was treated to become wet (wet with water).

Comparative Example 3 A test piece having a thickness of 5WILV was prepared by extrusion molding Sumitomo Noblen AD571. 1.1.1 as surface treatment
-) Steamed for 80 seconds with dichloroethane. Adhesion and shear peel strength of this test piece were measured in the same manner as in Example 1.

Comparative Example 4 A test piece prepared using the same resin and surface treatment method as in Example was adhered with an epoxy adhesive and the shear peel strength was measured.

Table 1 shows Example 1, Comparative Example 1.2. B. Shows the results of 4.

Table-1 Shear peel strength measurement results

Claims (1)

[Claims] The adhesive layer of a polyolefin resin molded product is irradiated with low-temperature plasma to reduce the surface twisting tension of the adhesive surface to 88 dynes/c.
After surface treatment to less than 265 dynes/cd,
A method of firmly adhering the adhesive surface and a painted metal surface using a component type urethane sealant.