JPH0558376B2 - - Google Patents

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to a method for molding a rubber molded product having a thin resin layer, and more specifically, the present invention relates to a method for molding a rubber molded product having a thin resin layer, and more specifically, it relates to a method for molding a rubber molded product having a thin resin layer, and more specifically, it relates to a method of molding a rubber molded product having a thin resin layer. The present invention relates to a method for molding a rubber molded product comprising a thin layer of a resin based on a rubber molded product and an insert on the back side of the rubber molded product using a mold into which a rubber material can be loaded in a sealed state.

Examples of rubber products to which the molding method of the present invention can be applied include automobile rubber parts such as strut bar retainers, bumper rubbers, bumper springs, slide stopper rubbers, stabilizer bushings, and strut bar bushings. .

<Prior art> Automotive rubber products such as those mentioned above are made with a hard material on the surface side of the rubber molded product, that is, on the interference side, to the extent that it does not impede the rubber elasticity, in order to prevent abnormal noises from occurring when there is interference with other parts. It has been considered to provide a thin resin layer (for example, ultra-high molecular weight polyethylene) (see Japanese Utility Model Application Publication No. 155213/1983).

The method for molding these rubber products is to apply resin powder to a predetermined thickness on the molded product surface side forming cavity surface of a mold into which the rubber material can be loaded in a mold-sealed state, and then to form a resin powder layer. One possible method is to set the insert in a mold, seal the mold, and then charge the material and mold the mold. Note that here, it is possible to use a resin film instead of the resin powder, but this is usually undesirable because the cavity surface has a three-dimensional curved surface.

<Problem to be solved by the invention> However, in the case of the above method, when loading the rubber material in a sealed mold state, due to the flow pressure of the charging material,
The powder resin layer partially flows, and as a result, the thickness uniformity of the thin resin layer formed on the molded product cannot be ensured.
Surface (appearance) defects were likely to occur.

An object of the present invention is to provide a method for molding a rubber molded product having a thin resin layer that can solve the above problems.

<Means for Solving the Problems> In order to solve the above problems, the method for molding a rubber molded product having a thin resin layer according to the present invention has the following configuration.

A rubber molded product comprising a thin layer of olefin resin on the front side of the rubber molded product body made of a non-polar rubber material and an insert on the back side of the rubber molded product can be loaded with the rubber material in a mold-sealed state. A molding method using a mold, the method comprising: forming a resin powder layer by applying olefin resin powder to a predetermined thickness on the molded product surface side forming cavity surface of the mold, and then forming a resin powder layer. On top of the mold, the primary material is loaded with the mold open, and when the mold is closed, the insert is placed in the mold so that it is placed in a position to compress the primary material. The feature is that secondary material is loaded and molded.

<Example> Here, an example will be explained in which a rubber molded product (strut bar retainer) having a shape as shown in FIG. 2 is molded, but the present invention is not limited to this.

(1) The above-mentioned rubber molded product is provided with an olefin resin thin layer 3 on the front side of a rubber molded product body 1 made of a non-polar rubber material, and an insert 5 on the back side of the rubber molded product. be.

Here, the reason why the rubber material is made non-polar is from the viewpoint of melt adhesion with the olefin resin. Here, examples of non-polar rubber include ethylene propylene rubber, styrene butadiene rubber,
Examples include synthetic rubbers such as isoprene rubber, butadiene rubber, butyl rubber, and natural rubber.

Examples of the olefin resin layer include hard types such as high-density polyethylene (PE) and crystalline polypropylene, but soft types such as low-density polyethylene may also be used. Particularly desirable is ultra-high molecular weight PE, which has an average molecular weight (viscosity method) of 1 million to 5 million, which is much larger than general high-density PE, and has excellent wear resistance and self-lubricating properties. Moreover, the thickness of the resin layer is 50 to 500 μm.

The insert is usually made of metal such as steel, but is not limited to any material as long as it has the required rigidity and heat resistance, and may be made of heat-resistant plastic,
It may also be made of ceramic or the like. If the insert is made of polar material, pre-glue it with adhesive.

(2) As the mold for the above rubber molded product, use an injection molding or transfer molding mold that can be filled with the material in a sealed state. In the illustrated example, it is for injection molding.

(3) Next, a molding method using the above materials and molds will be explained.

Olefin resin powder is applied to a predetermined thickness on the cavity surface 12 of the mold, that is, the lower mold 11, on the surface side of the molded product to form a resin powder layer 13 (FIG. 1A). Here, the particle size of the resin powder is
Depending on the thickness of the resin layer, a layer of 50 to 500 μm is used, and the coating method is to apply resin powder as is.
Alternatively, it can be applied as a liquid (suspension emulsion) by spraying or the like.

The primary material M1 is loaded onto the resin powder layer 13 in an open mold state (FIG. 1B).
As this primary material, a normal rubber material for compression molding may be used.

The insert 5 is set in the mold so that it is positioned to compress the primary material M1 when the mold is closed (FIG. 1C). The insert 5 may be placed directly on the primary material M1, that is, set in the lower mold 11, or may be set on the protrusion 17 of the upper mold 16 using an electromagnet or the like. .

The mold is closed, and in the mold sealed state, the secondary material M2
is loaded and molding is performed (Fig. 1D).

In this mold-sealed state, the resin powder layer 13 is pressed against the cavity surface 12 formed on the surface side of the molded product by the primary material M1 that receives compressive force through the insert 5. Therefore, even when the secondary material M2 is injected into the cavity, the resin powder layer 13 is not directly affected by the flow of the material, and is melted by the heating action of the mold for vulcanization. A thin resin layer with a uniform thickness is formed. In addition, among the above material loading methods, injection has a higher material heat content during loading than injection (transfer), and is preferable from the viewpoint of simultaneous adhesion of the insert and moldability (shortening of vulcanization time). .

In the above embodiments, although it is outside the scope of the present invention, if the surface of the rubber molded product on which the thin resin layer is formed is flat, a resin film may be used instead of the resin powder. Additionally, products without inserts can be molded by compression molding alone.

<Operations and Effects of the Invention> As described above, the method of molding a rubber molded product having a thin resin layer of the present invention includes applying olefin resin powder to a predetermined thickness on the molded product surface side forming cavity surface of the mold. After forming a resin powder layer, a primary material is loaded onto the resin powder layer in an open mold state, and an insert is placed in a position to compress the primary material when the mold is closed. The structure is characterized in that the mold is set in a mold, the mold is closed, and the secondary material is loaded and molded in the mold-sealed state, so that the following effects are achieved.

In the mold-sealed state, the resin powder layer 13 is pressed against the cavity surface 12 formed on the surface side of the molded product by the primary material M1 receiving compressive force through the insert 5. Therefore, even when the secondary material M2 is injected into the cavity, the resin powder layer 13 is not directly affected by the flow of the material, and is melted by the heating action of the mold for vulcanization. A thin resin layer with a uniform thickness is formed. Therefore, there is no risk of surface defects occurring on the surface of the molded product due to non-uniformity of the thin resin layer, unlike in the prior art.

In addition, the above molding method uses injection or injection, which has a higher vulcanization efficiency than compression molding and has a large material heat content during loading, in combination with compression molding, so it is difficult to mold by compression molding alone. The productivity is better than the case where the insert is used, and the adhesion between the insert and the rubber base material is also good.

[Brief explanation of the drawing]

1A to 1D are schematic cross-sectional views showing each step in an example of the molding method of the present invention, FIG. 2 is a cross-sectional view of the molded product molded in FIG. 1 (-line part in FIG. 3),
FIG. 3 is a half plan view of FIG. 2. 1... Rubber molded product body, 3... Olefin resin thin layer, 5... Insert, 11... Lower mold (mold), 12... Molded product surface side forming cavity surface,
13... Resin powder layer, 16... Upper mold (mold), M
1...Primary material, M2...Second material.

Claims (1)

[Scope of Claims] 1. A rubber molded product comprising a thin layer of olefin resin on the front side of a rubber molded product main body made of a non-polar rubber material and an insert on the back side of the rubber molded product. A method of molding using a mold that can be loaded in a sealed state, the method comprising applying olefin resin powder to a predetermined thickness on the molded product surface side forming cavity surface of the mold to form a resin powder layer. After that, a primary material is loaded onto the resin powder layer with the mold open, and an insert is set in the mold so that it is placed in a position to compress the primary material when the mold is closed, and the mold is closed. A method for molding a rubber molded product having a thin resin layer, characterized in that the mold is filled with a secondary material and molded in a sealed state.