JPH01159215A - Molding material made of synthetic resin involving air gap and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a chopping board made of synthetic resin which provides favorable touch of a blade, and is suitably elastic to reject its break, by involv ing an air gap in a core part. CONSTITUTION:Thermosetting synthetic resin such as vinyl chloride or polyethy lene or polypropylene is used and a molding mold is filled with the same. Then the same is pressurized with a pressurizing board 4 by pushing down a ram 3 and superheat molding is performed. After compression molding under super heat conditions, cold water is seat into a mold 2 and a molded product S is cooled with the water. About 5mm toward the center respectively from the surface A and backside B of a molding material are melted completely, the surface of a material pellet P is melted extending over about 5mm width of a core part 1 and an air gap K is formed by welding them to one another. As the air gap is involved in the core, the title molding material is light in weight, possesses appropriate elasticity, a warp is eliminated from the surface and backside, touch of a blade becomes favorable and favorable feeling of use can be kept for a long period of time.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is suitable as a molding material such as a mackerel, has excellent hygiene, and has a good feeling of use.
Moreover, the present invention relates to a synthetic resin molded material containing voids that is lightweight and easy to mass-produce, and a method for manufacturing the same.

[Prior art]

The fact is that manata materials, which are one of the synthetic resin molding materials, are now being replaced by synthetic resins from wood for resource saving and hygienic reasons.

Hitherto, various proposals have been made for synthetic resin mats that are homogeneous and have a good usability.
51757, Japanese Patent Publication No. 49-38871, Japanese Patent Publication No. 80-48170, Japanese Publication No. 413-1655
This is shown in Publication No. 1, etc.

By the way, conventional synthetic resin panniers are heavy, solid, durable, etc.
Compression molding, which has relatively low equipment costs, is not always sufficient, and products tend to have sink marks, warpage, etc., have a high rate of defective products that are fatal to the product, and pose problems in mass production. Ta.

For this reason, the reality is that injection molding, which requires expensive equipment, is used, and large injection molding machines are installed to satisfy mass production, and the materials are cut into appropriate sizes (for commercial use and home use).

[Problem that the invention seeks to solve]

However, whether it is compression molding or injection molding, in order to minimize the incidence of defective products, many considerations must be made regarding various conditions during molding, such as raw materials, molding temperature, molding time, molding pressure, degassing, and cooling. The molding process required a high level of skill, which also caused problems in terms of economy and mass production.

The present invention focuses on specific conditions that are considered problematic and should be avoided during conventional molding, and by utilizing them, the rate of defective products can be extremely simply reduced to almost zero without requiring any special molding technology. It has improved mass production and made it easier to manufacture.It is also lighter than conventional products, and has appropriate elasticity (repulsion) that makes it easy to grip the blade and prevents the blade from spilling when used as a knife. - The purpose is to provide a molding material suitable for use as a synthetic resin holder at a low cost.

[Means for solving problems]

The present invention provides a synthetic resin molded material in which a void is included in the core, and the synthetic resin is compression molded into a flat plate under heating, and after cooling, the void is included in the core of the flat plate. The present invention provides a method for manufacturing a synthetic resin molded material characterized by the following.

[Effect]

The synthetic resin molded material suitable as a container according to the present invention has voids (bubbles) included in the core, so it is lighter than conventional products, has appropriate elasticity, and has a surface and back surface. There is no warping, the blade has good contact, and it maintains a good feeling of use over a long period of time.

To manufacture such synthetic resin molding materials, thermosetting synthetic resins such as vinyl chloride, polyethylene, and polypropylene are used as materials, and particles of these materials are weighed and loaded into a mold. The mold is placed on the mold stand 1 of a downward compression molding machine as shown in FIG. 1 is shown in three stages, and is capable of compression molding six pieces at a time, but other known compression molding machines with improved mass productivity may also be used.

Next, the ram 3 is pushed down and the press plate 4 presses all the materials in the mold 2 at the same time, as shown in FIG. 2, and heat-forms them. The optimum temperature for compression molding varies depending on the material, but is generally about 130 to 180°C, and is controlled at this temperature, but in the present invention, molding is carried out under superheating above this optimum temperature. The superheating temperature is determined depending on each material, but by setting it to 200° C. or higher, for example around 230° C., the superheating temperature becomes common to various materials.

After compression molding under superheated conditions, cold water is sent into the mold 2 and circulated to water-cool the molded product S.
Although the molded product S shrinks internally and becomes easier to release from the mold, in compression molding, problems such as shrinkage and warpage after water cooling are less likely to occur as in injection molding.

In conventional compression molding of synthetic resins, overheating can cause so-called bubbles to form inside the product, resulting in defective products.
Care was taken to control the temperature to avoid overheating, and even at an appropriate molding temperature, the degassing operation was repeated as appropriate to prevent air bubbles from staying inside.
In the present invention, such precise temperature control is unnecessary, and a special intentional degassing operation may also be unnecessary or insufficient.

That is, in the case of the present invention, the shrinkage of the molded product due to water cooling after molding is significantly large, and when heating is completed at the above-mentioned superheating temperature and the pressure l1A4 is increased by the ram 3, the upper mold is Since it is lifted by the internal pressure of the resin, degassing is facilitated as a result.

In addition, there is almost no need to consider maintaining the optimum temperature range for conventional molding and degassing operations, which require particularly precise control during conventional compression molding, and compression molding can be performed under conditions that were conventionally considered as a tab. This is an extremely easy molding technique.

As shown in FIG. 3, it is a partially enlarged cross-sectional explanatory view of a molded product S according to the present invention, and the view is shown from the front surface A and the back surface B of the molded material (in the case of makinata, thickness 15 mm) toward the center. Approximately 5 mm of each is completely melted, and over approximately 5111I width of the core portion C, the surfaces of the pellets 2 of the material (high-pressure polyethylene) are melted and welded together to form a void K.

As described above, the present invention can manufacture a synthetic resin straddle whose core portion contains air bubbles.

〔Example〕

Next, examples of the present invention will be shown.

(1) Material High-pressure polyethylene (Note) The required amount of raw material is determined by the size of the pellets and the volume of the mold, but in the case of the following two-cavity mold mentioned in this example, 1.050 g was loaded into each mold. .

(2) Compression molding machine ■ 4-post hydraulic press 28 ton (■ Vertical multi-stage % type % 230 mm x 410 + + + m x 2 molds consisting of an upper mold and a lower mold for producing a 15 mm thick molding Place it on the mold stand under 3 tiers.

(4) Molding conditions ■ Heating temperature 230°C ■ Heating time 6 minutes, ■) Cooling time 5 minutes 40 seconds Note that the molded material manufactured under the condition that the cooling water is one cooling tower or higher is used as a product, for example. In this case, the desired size, for example, 230
When it was cut into a piece measuring 410 mm x 410 mm x 15 mm thick, there was a gap in the center of the warp with a thickness of about 5 mm parallel to the top and bottom surfaces, and the usability was extremely good.

〔Effect of the invention〕

As described above, according to the present invention, it is a synthetic resin molding material that is suitable as a receptacle, which was completely unthinkable in the past. It is difficult to clean, is clean and hygienic, does not deteriorate over a long period of time, has fewer defective products, is easy to mass produce, is lighter than conventional products, has a good grip on the blade, and does not cause the blade to spill. It has extremely beneficial effects such as being elastic and being inexpensive.

[Brief explanation of the drawing]

Fig. 1 is a front view showing an example of a compression molding machine for producing the synthetic resin molded material of the fourth invention, Fig. 2 is a perspective view during pressure molding, and Fig. 3 is a molded product (manufacturing material). ) is a partially enlarged cross-sectional view. l...Mold stand, 2...Mold, 3...Ram, 4...
・Pressure plate, S...molded product, K...void, P...pellet.

Claims (4)

[Claims] (1) A void-enclosed synthetic resin molded material characterized by having a void included in the core. (2) The void-containing synthetic resin molded material according to claim 1, wherein the molded material is a molded material. (3) A method for producing a void-inclusive synthetic resin molded material, which comprises compression molding a synthetic resin into a flat plate under superheating, and after cooling, the core of the flat plate includes a void. (4) The method for manufacturing a void-inclusive synthetic resin molded material according to claim 3, wherein the superheating temperature is around 230°C.