JPH0276716A - Method for forming finishing coat of weatherstrip - Google Patents

Abstract

PURPOSE:To eliminate the differences in color, in gloss and in level at joints between extruded part and formed part and remarkably reduce man-hours by a method wherein finishing coat is produced by film-extruding polyolefin- based thermoplastic elastomer under thermally molten state so as to fix onto a decorative surface by pressure. CONSTITUTION:Olefin-based thermoplastic elastomeric material, which is charged in a hopper 11, is melted and pressurized in stages by being pressure-fed with a screw cylinder 12 equipped with a heating means. The pressurized molten material is fed through a hose 13 to an extruding gun 14 so as to be film- extruded from the throttle nozzle 15 of the gun. In this case, a screw is driven by an electric motor 18 with reduction gears 17. Liquid pressure data, which are obtained by detecting pressures at the head 12a of the cylinder 12 with a pressure sensor provided at the head 12, are inputted in a comparison operator so as to be compared with the set value in order to control the rotational frequency of the motor 18 on the basis of the result of comparison to keep the liquid pressure at the set value at all times. Just after extrusion, the extruded coat is fixed to the main body side by pressure with a press roller.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides a method for forming a finish coating film on the designed surface of a weatherstrip body made of ethylene propylene rubber, in which an extruded part is connected to a molded part. Regarding.

Here, weather stripping refers to fixed window glass parts such as front and rear windows and quarter windows, hoods, etc.
They are attached to doors, doorstops such as sunroofs, and sliding parts such as doors and door glass, to insulate the interior of the vehicle from wind, rain, dust, noise, cold, heat, etc. from the outside world (``New Automotive Engineering Handbook'') Technical Society, Published January 10, 1980, No. 6 &i1-39 P). That is, the so-called
This includes window frame rubber, door weather strips, glass runs, etc.

<Prior art> The main body of weather strips used in automobiles, etc. is usually made of ethylene propylene rubber from the viewpoint of weather resistance, ozone resistance, heat resistance, etc., and the extruded part is connected to the molded part. . In addition, due to the increasing demand for improved design in automobiles these days, even in weather strips, problems such as differences in level, color, and gloss at the joining area between the extruded part and the molded part have not been considered problems in the past. Even small differences like these are becoming problematic.

<Problems to be solved by the invention> These problems are caused by the fact that the extrusion part and the molding part have different material compositions, and the material flow and curing behavior is different due to the fundamental difference in the molding method between extrusion and molding. Due to the difference, it is considered impossible with current manufacturing technology to match the color difference and gloss difference at the joining part, and the difference in level is 0.1 mm.
It is considered impossible to mold with the following control.

For this reason, it is conceivable to form a finishing coat by applying urethane to the designed surface of the weatherstrip body.

However, the film thickness of the finishing film of urethane coating is usually 30
The limit is ~50 μm, and although it is possible to eliminate differences in color and gloss at the joining site, it is not possible to eliminate differences in level.

In addition, urethane painting requires a lot of man-hours because after degreasing and cleaning the design surface (surface to be coated) of the main body, it is necessary to go through the steps of applying brimer, main painting (spraying), and drying.

In view of the above, the present invention provides a finishing coating for weather strips that can eliminate color differences and gloss differences at the joint portion between the extruded part and the molded part, as well as level differences, and can also significantly reduce the number of man-hours. The purpose of the present invention is to provide a method for forming a film.

Means for Solving the Problems> The present invention solves the above problems with the following configuration.

A method of forming a finish coating film on the designed surface of a weatherstrip body made of ethylene propylene rubber and having an extruded part connected to a molded part, the method comprising: applying a heat-molten polyolefin thermoplastic elastomer to the designed surface; It is characterized by forming a finish coating film by extruding a thin layer while pressing on top.

Detailed explanation of the means of the present invention> The means of the present invention will be explained in detail below. In addition,
In the following description, "parts" indicating a blending unit means "parts by weight." .

The method for forming a finish coating film according to the present invention is applied to a weather strip (window frame) made of ethylene propylene rubber and having an extruded part 1 connected to a molded part 3.4, as shown in FIG. 2A. Rubber) Applicable to the design surface of the main body 6 (see sectional view of the first surface).

Here, ethylene propylene rubber includes both those based on ethylene propylene copolymer (EPM) or ethylene propylene diene polymer (EPDM), but the latter, which can be vulcanized with sulfur, is usually used.

Tables 1 and 2 show an example of the formulation of each rubber material for the extrusion part and molding part.

A thin layer of thermoplastic olefin elastomer (hereinafter abbreviated as rTPOJ) in a heated and molten state is extruded onto the designed surface of the weatherstrip main body 6 (while being pressed) to form a finish coating film.

Here, olefin-based TPE refers to polyolefin-based plastics (PE% PP, etc.) with hard segments,
EP(D)M is a soft segment. Specifically, 1Sumitomo TPE” (product name: Sumitomo Chemical @
800 and 900 series of "Thermo Run" (product name: Mitsubishi Yuka ■manufacture and sales),
#3000 series, etc., which are appropriately selected and used depending on the body material and the required physical properties of the coating film. These materials are usually blended with carbon black from the viewpoint of coloring and physical properties, or are blended with white carbon and the necessary coloring pigments, and are also blended with other auxiliary materials as appropriate. do. The amount of carbon black added to 100 parts of TPO polymer is 0.
5 to 20 parts.

The thin layer extrusion is carried out using, for example, an apparatus (hot melt applicator) as shown in FIG.

The TPO material (pellet or powder) loaded into the hopper 11 is gradually melted and pressurized while being fed under pressure by a screw cylinder 12 equipped with a heating means. The pressurized molten material is fed via a hose 13 to an extrusion gun 14 and is extruded into a thin layer through a slot nozzle 15 of the gun. Here, the screw is driven by an electric motor 18 with a reduction gear 17. In addition, the pressure sensor installed in the head 12a of the cylinder 12 detects the hydraulic pressure at that location, and the hydraulic pressure data is manually input to a comparison calculation element to compare and calculate the set value. Based on the calculation result, the motor 18 The hydraulic pressure is always maintained at the set value by controlling the rotation speed of the pump. screw cylinder 12,
The heating temperatures of the hose 13 and the gun 15 are set so that the temperature increases stepwise from the hopper 18 attachment site (material input site) of the cylinder 12 toward the slot nozzle 15 side. For example, the temperature at the material input site is 130 to 150.
℃, and the temperature of the slot nozzle part is 230 to 250℃.

In this thin layer extrusion (coating film formation), it is desirable to press the coating film onto the main body side with a pressure roller immediately after extrusion. Also,
From the standpoint of improving adhesion, it is desirable to preheat the weatherstrip body immediately before forming the coating film.

The film thickness of the coating 1Ii8 at this time can be set to 100 to 500 μm, and as shown in FIG. The design quality is improved.

<Effects of the Invention> As described above, the method for forming a weatherstrip finish coating film of the present invention applies a finish coating film to the designed surface of the weatherstrip body, which is made of ethylene propylene rubber and whose extruded part is connected to the molded part. A method for forming a finish coat of 50 μm or more that can eliminate differences in level by extruding a thin layer of polyolefin thermoplastic elastomer in a heat-molten state onto a designed surface to form a finish coat. can be formed directly on the designed surface of the main body in one step, eliminating differences in color and gloss at the joint between the extruded part and the molded part, as well as eliminating steps, and also greatly reducing man-hours. .

<Example> Using a rubber material having the formulation shown in Table 1, it was extruded into the cross section shown in Fig. 1, vulcanized (conditions: 170°C x 10 minutes), and then cut to form each extruded member 1.1. I got .1.

Each extruded member was set in a mold, and molded using a rubber material with the formulation shown in Table 2 (vulcanization conditions: 170°C x 1
0 minutes) to form a molded part 3.4, and an annular weatherstrip (window frame rubber) main body 6 shown in FIG. 2 was prepared.

Using a hot melt applicator (see Figure 3), apply molten TPO resin material to the design surface of the weatherstrip body 6 that has been heated (80°C) in advance to a coating width of 10°C.
Finish coating film 8 was formed by thin layer extrusion with settings of mm x coating thickness of 200 μm. Immediately after forming the final coating film, the final coating film was pressed with a pressure roller (5 kg/cm'). The TPO material used above is “Sumitomo TPE901”100
5 parts of carbon black was used.

The heating conditions at this time were set to a temperature of 140° C. at the material input portion and a temperature of 240° C. at the slit nozzle portion.

The designed surface of the weatherstrip thus obtained had a black color with high design quality, and the level difference completely disappeared. In addition, in order to determine the adhesion of the coating film to the main body, a 180° peel test (pulling speed: 10 cm/min) was performed.
As a result, the peel strength was 5 kg/cm (rubber base material fracture).

Table 1 *Japan Synthetic Rubber - Manufactured Table 2 *Mitsui Petrochemical ■Manufacturing

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the weather strip obtained in the present invention (Fig. 2, line 1-1), Fig. 2 is a process diagram showing the method of the present invention, and Fig. 3 is a weather strip used in the method of the present invention. FIG. 2 is a schematic diagram of a hot melt applicator. DESCRIPTION OF SYMBOLS 1... Extrusion part, 3.4... Mold forming part, 6... Weatherstrip main body, 8... Finishing coating film, 12... Screw cylinder, 14... Extrusion gun, 15... - Slot nozzle, l...Joining part between the extrusion part and the molding part. Patent applicant Figure 3

Claims (1)

[Claims] A method of forming a finish coating film on the designed surface of a weatherstrip body made of ethylene propylene rubber and having an extruded part connected to a molded part, wherein a polyolefin thermoplastic elastomer in a heated and molten state is applied to the designed surface A method for forming a weatherstrip finish coating, comprising forming the finish coating by extruding a thin layer onto a surface.