JPH032892B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for surface treatment of a propylene resin molded article, and more specifically, a method for improving the paintability, printability, adhesion, etc. of the molded article by treating the surface of the propylene resin molded article with low-temperature plasma. Regarding. Propylene resin has mechanical and thermal properties,
Because it is a relatively inexpensive resin with excellent moldability, it is widely used in various fields, but its poor adhesion to paints, adhesives, etc. limits its use in applications that require painting, printing, and adhesion. Improvements in their adhesive properties are being considered. An effective method for this purpose is to improve the adhesion of the molded product surface by low-temperature plasma surface treatment using oxidizing gas. When trying to use plasma treatment in a method,
In order to satisfy the adhesive strength required in actual applications, there are economical disadvantages such as increased plasma oscillation output and increased processing time, so high adhesive strength can be obtained with low output and short processing time. Development of a plasma processing method is desired. In view of the current situation, the present invention provides a propylene-based resin molded product using low-temperature plasma, which provides high adhesive performance with low output and short-time processing, and is fully practical in terms of economy and processing performance. A surface treatment method is provided. The method for surface treatment of a propylene resin molded product of the present invention has a xylene solubility of 3 to 50% by weight at room temperature, and an ethylene content of 25 to 50% by weight in the xylene soluble matter.
It is characterized by treating a molded product made of 80% by weight propylene resin with low-temperature plasma. The propylene resin used here is a mixture of ethylene propylene block or random copolymer and ethylene propylene rubber or ethylene propylene diene rubber, with ethylene propylene block copolymer being particularly preferred. Such ethylene propylene block copolymers are disclosed, for example, in Japanese Patent Publications Nos. 40-11623 and 43-11230.
No. 44-16668, JP-A No. 49-61278, No. 49-
It can be obtained by using the manufacturing method described in Publications No. 53990 and No. 51-133393. these are,
Usually, it is a substantially crystalline resin composed of a block part made of a propylene homopolymer and a block part made of an ethylene propylene random copolymer containing a relatively high content of ethylene. Furthermore, ethylene propylene random copolymers are disclosed in, for example, JP-A-54-106593 and JP-A-56-33512.
No. 56-34714 and the like. These are generally substantially crystalline resins containing relatively low contents of ethylene. The propylene resin has a solubility in xylene of 3 to 50% by weight, preferably 4 to 40% by weight at room temperature,
It is particularly preferably 6 to 30% by weight, and the ethylene content in the xylene solubles is 25 to 80% by weight, preferably 30 to 70% by weight. If the xylene solubility at room temperature is less than 3% by weight or the ethylene content in the xylene solubles is less than 25% by weight, the adhesion improvement effect will be small, and the xylene solubility at room temperature will be 50% by weight.
If the ethylene content in the xylene-soluble matter exceeds 80% by weight, the surface layer of the molded product will tend to peel off into layers, making it impossible to obtain practical adhesive strength. Note that the xylene solubility at room temperature and the ethylene content in the xylene solubles are determined by the following measurement method. Xylene solubility at room temperature Approximately 0.7 g of sample was poured into approximately 300 c.c. of xylene, and 15
After dissolution by refluxing for a minute, the solution was allowed to stand at room temperature, cooled and filtered, and the liquid was evaporated to dryness, which was determined from the weight of the solid content. Ethylene content in xylene soluble content The xylene soluble content obtained in the above measurement was used as a sample and measured by ¹³ C-NMR method. The measuring device is a JEOL FX-200NMR device, and the pulse interval
Measured under conditions of 30 sec, pulse width 45°, and complete decoupling. The propylene resin may include plastics such as polyethylene, ethylene vinyl acetate copolymer, and homopolypropylene, elastomers such as styrene-butadiene block copolymer rubber, and inorganic materials such as talc, calcium carbonate, and glass fiber, as long as they do not impair the characteristics of the present invention. fillers, colorants, antioxidants,
An ultraviolet inhibitor or the like may be added as desired. The molded product may be molded by any method such as injection molding, extrusion molding, or blow molding, and is not limited to a specific product. Plasma treatment involves exciting a low-pressure oxidizing gas such as oxygen or a gas mixed with nitrogen, air, argon, carbon dioxide, chlorine gas, etc. using high-frequency discharge, microwave discharge, etc. to generate an active gas.
This is done by bringing it into contact with the surface of the molded article. Processing conditions are not particularly limited, but usually the pressure is 0.1 to 10 torr and the processing time is 5 seconds to 15 minutes. The effects of the present invention will be clarified by Examples and Comparative Examples below. <Example 1 and Comparative Example 1> Ethylene propylene copolymer obtained by polymerization (manufactured by Mitsubishi Yuka Co., Ltd., powder form) (Example 1-
~, Comparative Example,,) and a mixture thereof with ethylene propylene rubber (manufactured by Japan EP Rubber Co., Ltd., EP07P) (Example 1-, Comparative Example), the xylene solubility and xylene soluble content at room temperature shown in Table 1. Propylene-based resins with ethylene content in them are all added as antioxidants.
0.10% by weight of BHT (trade name, manufactured by Yoshitomi Pharmaceutical Co., Ltd.) was added, and a 50φ single screw extruder (manufactured by Thermoplastics Co., Ltd.) was used.
It was made into pellets. Adhesion test pieces were made using an injection molding machine (N made by Japan Steel Works, Ltd.).
−100) obtained by 100mm×100mm×3mmt
This is the board. Plasma surface treatment was performed using a microwave plasma treatment device (TMZ-9602B manufactured by Tokyo Shibaura Electric Co., Ltd.) using oxygen gas at a flow rate of 400 c.c./min, pressure of 0.5 torr, and output.
Processed at 400W for 10 seconds. The adhesion test was conducted using the following method. (1) 180° peel test A two-component curing urethane paint (manufactured by Nippon B Chemical Co., Ltd., R-263) was spray applied to a film thickness of approximately 80μ on the specimen after plasma treatment, and baked at 90℃ for 40 minutes. Ta. Next, a 10 mm wide cut was made in the coating film, and a strip of coating film was peeled off from one end, folded back in the opposite direction, and subjected to a 180° peel test (using Shimadzu Autograph P-100, pulling speed 10 mm/min). . (2) Paint film moisture resistance test The same paint as in (a) was applied to the test piece after plasma treatment to the same thickness.
It was spray coated to a thickness of 20μ, dried at 80°C for 30 minutes, and then left at room temperature for 2 days and nights. Then, it was suspended for 240 hours in a constant temperature and humidity chamber maintained at 50℃ and 95%RH, and then taken out.
After hours, I took a grid test. For the grid test, use a cutter to place 10 x 10 squares of 2 mm squares on the paint film, for a total of 100 squares, stick 24 mm wide cellophane tape on top of it, and forcefully peel it off diagonally to determine the number of squares that will not peel off. I counted. The results of the adhesion test are shown in Table 1. It can be seen that the examples in which the xylene solubility at room temperature and the ethylene content in the xylene solubles are within the range of the present invention have significantly higher coating film adhesive strength than the comparative examples outside the present invention.

[Table] <Example 2 and Comparative Example 2> Example 2 and Comparative Example 2 are respectively Example 1-
And to the propylene resin of Comparative Example 1-, 0.10 parts by weight of stabilizer IRGANOXRA1010 (trade name, manufactured by Ciba Geigy), 0.08 parts by weight of ultraviolet absorber Tinuvin 326 (trade name, manufactured by Ciba Geigy), and 0.5 parts by weight of carbon black. Automobile bumper made of material with added
cm x 20 cm) was plasma treated and then subjected to a painting test. The plasma processing equipment is shown in Figure 1, and the processing chamber has a diameter of 680 mm and a depth of 2000 mm.
A cylindrical chamber with a front door (made of steel, the inner surface is chrome plated) with an internal volume of approximately 700 mm, and an internal electrode consisting of a 2 mm thick aluminum punching plate with numerous 5 mm diameter pores, approximately 540 mm in diameter.
This aluminum electrode is a cylindrical electrode with a length of 1800 mm and a depth of 1800 mm, and is supported by an insulator and installed concentrically within the processing chamber. A high frequency voltage of 13.56MHZ was applied between the internal aluminum electrode and the external treated chamber wall (the oscillator was a model manufactured by Shimada Rika Kogyo Co., Ltd.).
The cable is connected so that SGD-102F-1A) can be applied. A gas flow meter and processing gas inflow holes are provided at the top of the processing chamber. A processing gas exhaust hole is provided at the bottom of the processing chamber and is connected to a vacuum pump. Place the bumper in the inner cylinder, and maintain the pressure at 0.25 torr while oxygen flows in at 100 c.c./min.
Plasma treatment was performed at 500W for 60 seconds. Next, the same paint as in Example 1 was spray-coated to a thickness of about 35 μm, and baked at 90° C. for about 1 hour to dry. The paint film adhesion test was conducted in the following manner. 10 x 10 squares of 2mm square on the paint film surface at 4 locations each on the top and both sides of the bumper
A total of 100 incisions were made with a cutter, 24 mm wide Sellotape was pasted on top of the incisions, and the tape was strongly peeled off to count the number of squares in the coating that did not peel off. In Example 2, the coating film adhesion residual rate was 100/1 at each position.
It was 100. On the other hand, in Comparative Example 2, there were five locations where the adhesion residual ratio was 90/100 to 98/100.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a plasma surface treatment apparatus used in Example 2.

Claims (1)

[Claims] 1 The xylene solubility at room temperature is 3 to 50% by weight, and the ethylene content in the xylene solubles is 25 to 80%.
% by weight of a propylene resin molded article, the surface of the molded article being treated with low temperature plasma.