JPS6140329A - Method of surface treatment of synthetic resin surface to be bonded - Google Patents

Abstract

PURPOSE:To clean the surface of resin to be bonded and to raise bonding strength simultaneously in a good operation environment in a short time inexpensively, by spraying abrading granules to the surface of resin to be bonded with pressurized air by sand blast processing to remove dust and organic substances, and making the surface uneven. CONSTITUTION:A great number of abrading granules are sprayed upon the surface of synthetic resin to be bonded with pressurized air by sand blast processing, admixtures and organic materials are removed by the abrading granules, and a large number of uneven parts are formed. Carborundum, Alundum, alumina, diamond, emery, garnet, boron carbide, red iron oxide, chromium oxide, glass powder, calcined dolomite, silicic anhydride, etc. are used as the abrading granules, and particles having 50-2,000 meshes are sprayed at 2-15kg/cm<2> air pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention is directed to the prevention of dust and debris that adhere to the synthetic resin bonding surface before bonding.
The present invention relates to a surface treatment method that removes dust, organic matter (oil, fat, mold release agent, hand stains), etc., and forms countless ``irregularities'' thereon to enhance adhesive strength.

B. Prior Art As methods for pre-treating adhesive surfaces, there are two known methods: a chemical method in which a bond is treated with a chemical solution that is degreased with a solvent, and a mechanical method in which the surface is degreased by rubbing the surface with a puff or the like. Both methods depend on the type of synthetic resin,
Either one can be selected by considering the shape, required adhesive strength, application, etc.

However, when high adhesive strength is required, chemical methods have been considered better than mechanical pretreatment methods. The chemicals used for chemical pretreatment vary depending on the type of synthetic resin, but they can dissolve part of the synthetic resin adhesive surface to form an uneven surface, or create an oxide film or polarity to improve adhesive strength. are doing.

In addition, as a method different from these methods, there is a flame treatment in which the synthetic resin adhesive surface is burned with a Bunsen burner, a high voltage electrode is placed opposite the adhesive surface, and a corona discharge is caused between the electrode and the adhesive surface to heat the adhesive surface. A method has been developed in which corona discharge treatment creates all the irregularities on the surface, and a method in which inert gases such as helium, argon, and krypton, as well as hydrogen and nitrogen gases are activated by electrodeless discharge and collided with the synthetic resin adhesive surface. .

For example, chemical solutions such as sulfuric acid-chromic acid, liquid ammonia solution of sodium metal, aqueous caustic soda solution, methanol, and acetone are used in chemical methods, but these chemicals require considerable effort to dispose of waste liquid after use. Furthermore, even if the surface to be bonded with the synthetic resin is made uneven, it takes a considerable amount of time, ranging from several minutes to several hours. Synthetic resins bonded using chemical pretreatment, which requires a short processing time, have the drawback of extremely low peel strength, apart from shear strength.

In addition, flame processing using a burner makes it extremely difficult to uniformly process the entire surface of the adhesive surface, which may result in over-baking and scorching or thermal deformation of the adhesive surface, or insufficient pre-treatment and partial adhesion. There was a drawback that there was a weak part.

Furthermore, the method using corona discharge not only cannot remove most of the organic matter that adheres to the surface, but also makes it difficult to create deep irregularities because the ions generated during the discharge hit the synthetic resin adhesive surface, and moreover, it is difficult to create deep irregularities on the entire adhesive surface. It has the disadvantage that it takes time to form countless unevenness without gaps, and the processing cost per unit time is high. Another drawback was that a large amount of ozone was generated due to corona discharge, making the working environment poor.

Furthermore, even the method using an inert gas has the disadvantage that the processing cost is extremely high.

C1 Objectives of the Present Invention The features required of the surface treatment method for synthetic resin adhesive surfaces can be summarized as follows.

■ Processing costs are low, deep unevenness can be created in a short time, and strong adhesive strength can be obtained.

■ At the same time as creating a concave or convex surface, foreign matter and organic materials adhering to the surface can be removed.

■ Apply uniformly to synthetic resin adhesive surfaces of a wide variety of shapes [t'
[In addition, the type of synthetic resin must not be specified.]

■ The treatment process does not generate harmful waste liquids, gases, or gases, and the working environment is good.

■ It has no directionality and has strong peel and shear strength in all directions.

The present invention was developed with the aim of simultaneously satisfying the above-mentioned features (1) to (2).

D. Means and Effect for Solving the Conventional Problems Numerous abrasive grains are sprayed with air on the synthetic resin adhesive surface by sandblasting. The abrasive grains, which have a large amount of kinetic energy at high speed, collide with the adhesive surface of the synthetic resin, scraping off a part of the synthetic resin surface to form a recess, and knocking away foreign matter and organic matter adhering to the surface. It is blown away by air currents and removed. The adhesive surface that the abrasive grains collide with at high speed creates a depression in the direction of movement of the abrasive grains. When the abrasive grains collide not parallel to the bonding surface but substantially perpendicular to the bonding surface, a substantially circular depression is generated in the bonding surface. The countless abrasive particles create countless irregularities on the synthetic resin adhesive surface one after another in a short period of time. Large abrasive grains have large kinetic energy and form thick and deep dents when they collide. Therefore, by adjusting the particle size of the abrasive grains and the air pressure, the depth of the uneven surface and the roughness of the surface can be freely adjusted. The abrasive grains that collide with the synthetic resin bonding surface, foreign matter peeled off from the bonding surface by the abrasive particles, and synthetic resin powder scraped off by the abrasive particles are blown away by the high-speed air flow and removed from the bonding surface.

E. Preferred embodiment Embodiments of the present invention will be described below based on the drawings.

Example 1 A core material 1 of a fan made of polypropylene, shaped like a hand as shown in FIG. 1, is placed horizontally on a rubber-like elastic plate 2 as shown in FIG. (D core material IK, abrasive grains are sprayed with pressurized air by sandblasting.

As the abrasive grains, 120 mesh silica sand was used, the pressurized air pressure was 6:9/d, and the processing time was 10 seconds.

A nitrile-phenolic adhesive was applied to the core material 1 whose surface was treated in this manner, and paper was adhered thereto. The paper fan manufactured using this method has a peel strength that is as strong as that of paper that is superior to those made by burning the surface of the core material 1 with a burner and bonding paper with a similar adhesive. Obtained.

In addition, with the burner pretreatment method, approximately two defective products were produced, but with the sandblasting method of the present invention,
We were able to significantly reduce the number of defective products to less than 0.3%.

As mentioned before, the pre-treatment method for baking with fire is difficult because it is difficult to flame-treat the entire surface of the core material 1 uniformly. It was not possible to reduce the number of defective products that partially deformed due to heat to less than 2%.

Furthermore, during the sandblasting process, the burrs protruding from the core material 1 during molding were also removed, making it possible to save labor in the burr removal process, thereby reducing the reduction in adhesive strength and product value caused by burrs.

Example 2 A polyethylene sheet was placed on a base, and 20
0 mesh carborundum was sprayed at an air pressure of 8 to 9/cII for 5 seconds, and the sandblasted surfaces of the film were adhered to each other with an epoxy-giri sulfide adhesive. The polyethylene film bonded by this method has a peel strength of 1 crn equivalent to that of the P and E films that were immersed in a sulfuric acid-chromic acid mixture for 60 minutes and bonded after drying.
A force of 5 kg was required to peel off the width of the film.

Example 3 1) 0 mesh of silica sand was sprayed onto the surface of a polyethylene film at an air pressure of 5 kg/d for 5 seconds, and phenol was applied to the surface with a brush.

Paints applied in this way are potassium dichromate 15 & 9
．． A mixture of 8 water and concentrated sulfuric acid with an OIc of 9.96% or more.
The adhesive strength was equivalent to that of a polyethylene film heated to 0.degree. C. and immersed in this for 10 minutes.

By the way, in this specification, the surface treatment method for a synthetic resin adhesive surface is interpreted in a particularly broad sense, and the adhesive surface where a paint is applied to a synthetic resin surface and the paint is adhered is also considered to be a synthetic resin adhesive surface. Therefore, the term also includes surface treatment methods prior to coating the paint.

Implementation N4゜The synthetic rubber-based pressure-sensitive adhesive can adhere synthetic resins, wood, etc. to the surface of untreated polyolefin-based synthetic resins. However, this type of adhesive cannot achieve sufficient adhesive strength. Particularly when peeling force is continuously applied for a long time, it peels off easily.

60 mesh to 2 on the surface of polyolefin fin type synthetic resin
When sandblasting is performed by blasting 00 mesh silica sand with air at 9/I at a pressure of 2 to 15 seconds to several tens of seconds, polarity is imparted to the synthetic resin adhesive surface. This synthetic resin adhesive surface could be strongly bonded with an epoxy or synthetic rubber-phenol adhesive with high adhesive strength.

Example 5 Only e-positive adhesives can be used with fluororesin unless the adhesive surface is surface-treated.

Fifty meshes of glass powder was sprayed onto the surface of the fluororesin at an air pressure of 8 IC9/d for 30 seconds, and a piece of stainless steel was adhered to this using an epoxy adhesive.

The fluororesin and stainless steel piece bonded using this method are
24kg/CI at room temperature 15℃! The shear strength was obtained.

By the way, 1. Conventional surface treatment, i.e. fluororesin, 1
The surface of the present invention was immersed for 5 seconds in a liquid ammonia solution containing % metallic sodium, then washed with alcohol, washed with water, and then adhered to stainless steel using the same adhesive. Adhesive strength was slightly weaker than treated.

The abrasive grains that can be used in the sandblasting of the present invention are all those that can scrape off a part of the synthetic resin adhesive surface by colliding with it, such as alundum, diamond, emery, garnet, boron carbide, red iron, chromium oxide, Glass powder, calcined dolomite, silicic acid, etc. can be used.

The particle size of the silica sand is, for example, 50 to 2000 mesh, preferably 60 to 30 mesh, taking into account the type of synthetic resin, the required adhesive strength, the type of adhesive used, the condition of the bonded part, etc.
It is determined to be approximately 0 meshes.

Furthermore, the air pressure to inject the abrasive grains is usually 2 to 15 to 9/
It is determined to be about d.

F0 Effects of the Invention The surface treatment method of the synthetic resin bonding surface of the present invention is a simple method of spraying abrasive grains with pressurized air for a short period of time, and deep unevenness can be formed on the synthetic resin bonding surface, and at the same time Adhesive foreign matter and organic matter are removed, resulting in strong adhesive strength that is comparable to conventional surface treatments. In addition, even if the synthetic resin adhesive surface of the sandblasted abrasive grains is flat,
Even complex three-dimensional curved surfaces can be uniformly processed and can be made into a variety of shapes. In addition, most types of synthetic resin adhesive surfaces can be surface-treated, and the treatment process does not generate any harmful waste liquid or gas. It has the excellent effect of forming streak-like unevenness on the surface of the surface, which prevents directionality, and can form the ideal unevenness for bonding.

Conventionally, when laminating synthetic resin films after pretreatment by corona discharge machining, or when bonding and sealing corona discharge machined synthetic resin films, there is a drawback that the adhesive surface may peel off or the sealing performance may deteriorate. However, compared to corona discharge, the synthetic resin film surface-treated by the sandblasting method of the present invention has countless unevenness formed on the entire surface, both macroscopically and microscopically, uniformly without any gaps, and the laminate part and seal are The adhesive strength of the parts is increased.

In addition, when printing on a surface, similar to applying paint to a synthetic resin surface, the conventional method using corona discharge did not allow printing ink to adhere strongly, but with the method of the present invention, the surface can be treated. Synthetic resin films have strong adhesion to printing ink, and subsequent peeling can be minimized.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the core material of a fan to which the present invention is applied;
FIG. 2 is a view showing the state in which the surface of the core material is sandblasted. 1. Core material, 2. Rubber-like elastic plate,

Claims (6)

[Claims] (1) Numerous abrasive grains are sprayed with pressurized air onto the synthetic resin adhesive surface by sandblasting, and these abrasive grains remove foreign matter and organic matter from the synthetic resin adhesive surface and form countless irregularities. , a surface treatment method for a synthetic resin adhesive surface that allows the adhesive surface to adhere strongly even with this unevenness. (2) Carborundum, alundum, alumina, diamond, emery, garnet, boron carbide, red iron oxide, chromium oxide, glass powder, calcined dolomite, and silicic anhydride are used as the abrasive grains sprayed onto the synthetic resin adhesive surface. A method for surface treatment of a synthetic resin adhesive surface according to claim (1). (3) The method for surface treatment of a synthetic resin adhesive surface according to claim (1), wherein abrasive grains having a mesh size of 50 to 2000 are used. (4) The air pressure to inject the abrasive grains onto the synthetic resin adhesive surface is 2k.
g/cm^2 to 15 kg/cm^3. The method for surface treatment of a synthetic resin adhesive surface according to claim (1). (5) A method for surface treatment of a synthetic resin adhesive surface according to claim (1), in which a three-dimensional synthetic resin adhesive surface is subjected to sandblasting. (6) A method for surface treatment of a synthetic resin adhesive surface according to claim (1), which comprises forming countless irregularities on the synthetic resin adhesive surface by sandblasting and removing burrs during molding.