JPS6228814B2 - - Google Patents

Description

Detailed Description of the Invention This invention improves the paintability, printability, adhesion, etc. of a molded product by treating the surface of a molded product made of a composite resin in which a propylene polymer is filled with ethylene propylene rubber or the like with low-temperature discharge plasma. Concerning how to improve. Resin surface treatment technology is useful in commercializing resin products and in increasing the versatility of products.
It is essential. However, in the case of polypropylene resin, etc., its properties are crystalline and non-polar, so it is not possible to paint the surface of the molded product (paintability), print (printability), or adhere objects. (adhesion) was considered difficult. Subsequently, surface treatment technology for polypropylene resin was also researched and developed, leading to gradual improvements in paintability, printability, and adhesion. Surface treatment technologies that have been established so far include:
The main methods known are chromic acid treatment, corona treatment, and flame treatment, but each has its own problems.
The application of the processing technology is limited. For example, in chromic acid treatment, there is a problem in waste liquid treatment, in corona treatment, the surface treatment target is limited to thin objects such as films and sheets, and in frame treatment, there is a problem in surface treatment. There is a problem that the object is limited to a simple shape. The low-temperature plasma treatment according to the present invention is a surface treatment technology that has been developed to solve these problems and be applicable to a wide range of applications. However, even in low-temperature plasma treatment, there is a problem in that the effect is not so pronounced depending on the resin to be treated. For example, even if the surface of a homo-polypropylene resin molded product was treated with low-temperature plasma, the paintability, printability, and adhesion properties were not significantly improved, and the result was poor in practical use. The purpose of this invention is to provide a solution to the above-mentioned problems, and the purpose of this invention is to provide a method for solving the above-mentioned problems.When a certain composition resin is subjected to low-temperature plasma treatment, the paintability, printability, and adhesion are improved compared to conventional examples. The object of the present invention is to provide a surface treatment method that significantly increases the effect and exhibits excellent practical effects. The details of this invention will be explained below. In this invention, the pressure is 100 mmHg or less, preferably 0.1
~10 mmHg of a gas such as oxygen, nitrogen, argon, helium, etc., preferably oxygen, is excited by a desired discharge such as glow discharge or high frequency discharge to generate low-temperature plasma, and in this atmosphere, propylene polymer is mixed with ethylene propylene rubber. Alternatively, a molded product obtained by molding a composite resin filled with 2 to 40% by weight of ethylene propylene diene rubber is placed and subjected to the low-temperature plasma treatment, or the low-temperature plasma is sprayed onto the surface of the molded product. It's a method. Here, the propylene polymer may be homopolypropylene, ethylene propylene copolymer, copolymer of propylene with a small amount of other monomer, polyethylene polypropylene mixture, etc. A copolymer of a small amount of monomer and propylene, a mixture of polyethylene and polypropylene, etc. mixed with rubber or other fillers, or a mixture with antioxidants, pigments, etc. may also be used. Particularly preferred materials include ethylene content of 15
~25% by weight, propylene-ethylene copolymer with MI of 2.0-3.0, 60-80% by weight, 10-20% by weight of ethylene-propylene rubber with an ethylene-propylene molar ratio of 80-20:20-80, and high-density polyethylene 10~20
A resin consisting of % by weight is used. Further, the molded surface made of such a resin may be an injection molded product, a blow molded product, an extrusion molded product, etc., and is not limited to a specific product. Next, the plasma processing conditions, such as the type of gas, pressure processing amount, processing time, temperature, output, etc., are not particularly limited and the processing can be performed using normal conditions. was found to have a large effect on the surface texture. That is, plasma treatment requires a certain amount of treatment or more in order to improve surface activity, but when the treatment amount is increased, the contact angle and gloss level decrease in accordance with the treatment amount. However, it has been found that paintability, printability, and adhesion are improved at a certain range of processing amount, but are conversely reduced when the processing amount exceeds that range. Focusing on this phenomenon,
As a result of various studies, the processing amount can be expressed by the following equation using the discharge section output wattage [w], the processing time t [sec], and the processing chamber volume V []. Processing amount = w x t/V [w sec/] The surface activity improvement effect is achieved when the processing amount is ``100~
60000w sec/" preferably 200~30000w
It was found that it was large in the range of 1.sec/'. Next, examples of the present invention will be shown, and when the resin molded article according to the present invention is subjected to low temperature plasma treatment under desired conditions, the resin surface not only becomes polarized but also exhibits a surface roughening phenomenon. It is revealed that the paintability, printability, and adhesion of resin molded products are significantly improved. Example 1 (Including Comparative Example 1) This example describes a test piece of a molded product according to the present invention obtained by injection molding a composite resin in which polypropylene contains 10% by weight of ethylene propylene rubber. On the other hand, in Comparative Example 1, a molded test piece obtained by injection molding was subjected to plasma treatment in the same manner as in Example 1 for a polypropylene-only resin containing no ethylene propylene rubber. . Both Examples and Comparative Examples were subjected to plasma treatment under the same conditions, and by the test method described below,
An experiment was conducted to examine how the differences in the materials of both materials affect the processing effect. (1) Plasma treatment conditions (a) Plasma treatment machine IPC-2005 high frequency plasma treatment equipment (b) Plasma treatment method Gas body: Oxygen Gas flow rate: 300c.c./min Gas pressure: 1mmHg Temperature: 50 to 80℃ Output Power: 100w Processing time: 0 to 15 minutes (c) Molding test piece injection molding machine: Meiki Seisakusho SJ45C Test piece: 100mm x 100mm x 3mmt (plate shape) (2) Measurement items (a) Test piece comrades after processing were adhered with Aron Alpha (manufactured by Toagosei Chemical Industry Co., Ltd.), and after curing, the peel strength was measured. (b) In order to investigate the surface activity due to plasma treatment, the contact angle of the treated specimen with water was measured. (c) In order to examine the unevenness of the surface, the glossiness of the treated specimen was measured. (3) Measurement method (a) Cyanoacrylate adhesive strength test method ○…

Claims (1)

[Claims] 1. A gaseous body such as oxygen, nitrogen, argon, helium, etc. under a pressure of 100 mmHg or less is applied to the surface of a molded product made of a composite resin in which propylene polymer is filled with 2 to 40% by weight of ethylene propylene rubber or ethylene propylene diene rubber, using glow discharge or other means. A surface treatment method characterized by irradiating low temperature plasma excited and generated by electric discharge and improving the surface performance of the molded article at a plasma treatment amount of 100 to 60,000 Wsec/.