JPS6038249B2 - Method for manufacturing thermoplastic resin molded products with anti-slip properties - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of attaching a non-slip device to a thermoplastic resin molded product, particularly a polyolefin molded product, and integrally thermally adhesively molding the molded product.

Conventionally, methods are known in which rubber-like substances are attached to required parts of polyolefin resin molded articles in order to prevent them from slipping, but these methods involve creating recesses in the rubber-like substance and filling them with molten resin. conversely, creating a recess in a resin molded product and attaching a rubber-like anti-slip tool to that location, adhering with an adhesive or other adhesive, or There are methods such as filling resin with sulfur rubber and heating and vulcanizing it, but with the method of creating recesses and fixing with iron fittings, it is not possible to firmly mount anti-slip devices of various shapes, and furthermore, Since the anti-slip tool is simply bonded to the resin, it has the disadvantage of slipping off due to external force.

Furthermore, in the method of bonding the anti-slip device to the molded product using an adhesive, sufficient adhesive strength cannot be obtained because thermoplastic resins, particularly polyolefin resins, are non-polar. Also Hakama Kaisho 48-1510
The method of heat vulcanization using unvulcanized rubber, as shown in Japanese Patent No. 62, has the disadvantage that the molding cycle time is extremely long and productivity is poor.

The purpose of the present invention is to overcome the drawbacks of these conventional methods and to
To provide a method for attaching a strong anti-slip device which has quick productivity in a molding cycle for making a normal molded product and does not come off due to external force, and also allows attachment of anti-slip devices having various shapes. be.

In other words, the gist of the present invention is that when manufacturing a molded article with a non-slip feature using a thermoplastic resin as a raw material, a non-slip tool made of thermoplastic rubber or a mixture of thermoplastic rubber and thermoplastic resin is attached to the inner surface of a mold in advance. After placing the molten thermoplastic resin at the required location, a molten thermoplastic resin is introduced into the mold to form the molten thermoplastic resin layer, and the molten thermoplastic resin layer is thermally molded integrally with the anti-slip shell. A method for manufacturing thermoplastic resin molded products.

The manufacturing method of the present invention can be applied to all fields in which molded products are produced using molds for molded products, and specifically, injection molding, blow molding, vacuum-pressure molding, and rotary molding. Can be applied.

There are various molded products that can be obtained by such a molding method, but the present invention is particularly applicable to molded products that require anti-slip properties, such as plastic pallets, plastic transport boxes, plastic containers, plastic chairs, plastic chairs for everyday use, and others. It is applied to molded products that may require anti-slip properties. Thermoplastic resins used as raw materials in the present invention include polyolefins such as high-density polyethylene, low-density polyethylene, medium-density polyethylene, isotactic polypropylene, ethylene-vinyl acetate copolymers, and copolymers and mixtures thereof. Furthermore, it is a general thermoplastic resin such as polystyrene, ABS resin, polyvinyl chloride, polyamide, polyester, etc., and additives such as pigments, stabilizers, and blowing agents, or reinforcing agents such as glass fiber, etc. are added to the thermoplastic resin. may also be used in the present invention.

The thermoplastic rubber that is the material of the anti-slip tool in the present invention is also called a thermoplastic elastomer, and in many respects it behaves like ordinary vulcanized rubber, but it plasticizes and melts or softens when heated, leaving it as it is. If the temperature is lowered in the state (without vulcanization), it exhibits rubber properties (elasticity), such as styrene-butadiene block copolymer (``Califlex'' by Shell Chemical Co.), styrene-isoprene flock. Copolymers (Shell Chemical Co., Ltd.'s "Califlex"), polyolefin-based thermoplastic elastomers (DuPont's "Somer"), polyurethane-based or polyester-based thermoplastic elastomers, and ethylene acrylate copolymers/ethylene These are generally known thermoplastic resins having elastomeric properties such as vinyl acetate copolymers.

However, in order to use the thermoplastic rubber alone as a non-slip tool, it is preferable to have a high rigidity from the viewpoint of wear resistance.If a thermoplastic rubber with low rigidity is used, as will be described later, a thermoplastic rubber is used for the thermoplastic rubber. It is preferable to mix them together because it can increase rigidity, wear resistance, and tensile strength.

Further, fillers, reinforcing agents, stabilizers, coloring agents, etc. may be blended with these thermoplastic rubbers as necessary.

Also, mixtures of thermoplastic rubbers with thermoplastic resins such as high-, medium-, and low-density polyethylene, polypropylene, ethylene-vinyl acetate copolymers, and polystyrene are also used as anti-slip odor materials. It is preferable to use a thermoplastic resin that is similar to or has good compatibility with the resin used in the molded product, as the anti-slip effect will decrease as the content of the thermoplastic resin increases. Generally 0-7
The thermoplastic resin content is preferably in the range of 0 to 50% by weight. In other words, if the thermoplastic rubber used is relatively flexible, even if the rubber sheet is held in the mold, it may be deformed or not fixed due to stress such as large shearing when filling the resin. Therefore, even if it is fixed and embedded in a molded product, it may not be useful as a non-slip device, so it is preferable to use such a flexible thermoplastic rubber mixed with a thermoplastic resin. Furthermore, the thermoplastic resin used here must not have a very high softening point or melting point considering its purpose. Any known method may be used to blend the thermoplastic resin into such thermoplastic rubber, but in order to obtain a homogeneous blend, for example, the two may be dry-blended and then kneaded using an extruder or Banbury mixer. There is a way to do it. As mentioned above, these thermoplastic rubbers have the property of being easily plasticized by heating, so a non-slip tool made of thermoplastic rubber or a mixture of thermoplastic rubber and thermoplastic resin is held on the inside of the mold. At the same time, when the molten resin is poured, the surface layer of the anti-slip tool is heated and becomes a molten or semi-molten state, and is thermally fused with the poured thermoplastic resin and fixed to the surface of the molded product after cooling.

In this way, a thermoplastic molded product with an anti-slip odor attached to a desired location can be easily and quickly obtained, and the anti-slip tool does not come off. As the material for the anti-slip tool, rubber-like substances other than thermoplastic rubber or a blend of thermoplastic rubber and thermoplastic resin are not preferred. The method for holding the anti-slip tool on the inner surface of the mold should be selected taking into account the shape of the anti-slip tool, but in either method, the method will not hold the molten thermoplastic resin until it is completely filled into the mold. Must be retained on the inner surface of the mold.

For example, if the anti-slip device is flat and has a small thickness, the anti-slip device may be fixed to the inner surface of the mold using adhesive or pressure-sensitive adhesive or double-sided adhesive tape as shown in FIG. However, in such a method, depending on the type of adhesive or adhesive, the anti-slip device may move from the desired location or peel off from the mold surface when molten resin is filled into the mold. Care must be taken in selecting the agent or adhesive. Furthermore, the anti-slip tool must be easily peeled off from the mold surface when the mold is filled with molten resin and cooled, and then the mold is opened to take out the molded product. It is necessary to pay attention to this point when selecting an adhesive or pressure-sensitive adhesive. Such adhesives or pressure-sensitive adhesives have adhesive strength at room temperature or low temperature, but deteriorate in adhesive strength at high temperatures, that is, molding temperatures.For example, cyanoacrylate-based, epoxy-based, or rubber-based adhesives are preferred. Cyanoacrylate-based adhesives are preferred because they bond quickly with contact pressure. Furthermore, if the shape of the anti-slip tool is a flat plate and has a large thickness, or if it has a complicated shape, a holding pin should be provided on the inside of the mold and the anti-slip tool should be provided with a holding pin as shown in Figure 2. By forming a shape with a recess into which the pin is carried, movement of the anti-slip tool due to mechanical fitting is prevented.

In addition, as described above, methods for filling the molten resin into the mold include injection molding, blow molding, and vacuum pressure chamber molding, but the present invention is particularly effective in injection molding. This phenomenon is thought to be due to the fact that in injection molding, molten resin is filled into the mold under high pressure.

Therefore, the molding conditions in injection molding will be explained. The melting point or softening point of the anti-slip odor thermoplastic rubber used in the present invention or a mixture of thermoplastic rubber and thermoplastic resin varies depending on the thermoplastic rubber used, but is approximately the melting point of the thermoplastic resin. Alternatively, it is not much different from the softening point, and is within the range of about 100 to 25,000. Therefore, the injection conditions for the thermoplastic resin may be those normally employed. For example, when using high-density polyethylene, the injection temperature is preferably in the range of 1600 to 28000, preferably 180 to 250oo, and the mold temperature is 40q.
Normal conditions in the range of o to 90°C may be used. If the temperature of the injection resin is below 16,000, injection molding itself is difficult, and it is also difficult to fuse the resin with the anti-slip tool. On the other hand, the temperature is 280
If the temperature exceeds .degree. C., the thermoplastic rubber will deteriorate, which is not preferable. The present invention will be described in detail below with reference to the drawings and examples and comparative examples, but the invention is not limited to the drawings and examples.

Figures 1 and 2 show specific examples in which a non-slip device 2 is held on the inner surface of a mold 1 using thermoplastic rubber or a mixture of thermoplastic rubber and thermoplastic resin. The shape of the tool is a flat plate and the thickness is small, whereas the anti-slip tool shown in FIG. 2 is relatively large in shape and thick. In FIG. 1, the anti-slip device is held on the inner surface of the mold 1 with adhesive or other methods, and in FIG. It is held on the inner surface of the mold by bringing the recess into the provided pin 3. After that, the mold 1' is sealed and the resin 5 is released under high pressure from the resin runner 4.
fills the space inside the mold. At this time, the anti-slip tool 2 and the resin 5
are hot-bonded, and when the molds 1, 1' are opened after cooling, the anti-slip device 2 is completely attached to the molded product. The molded product in FIG. 1 is shown in FIG. 3. Examples 1 to 7 When injection molding a drainboard with a shape of 500 x 500 x 75 and a rib weight of 3k9, molds with a shape of 30 x 6 were placed at four locations on the inner surface of the mold.
The anti-slip device of the 0x2 fence sheet was held in place using a cyanoacrylate adhesive (method as shown in Figure 1).

Prior to this, the surface of the anti-slip tool was washed with inpropyl alcohol. Further, as the material of the anti-slip tool, various thermoplastic rubbers or a mixture of thermoplastic rubber and thermoplastic resin, which will be described later, were used. After holding the anti-slip device in the mold, the mold is closed, and plasticized high-density polyethylene (trade name (Stafrene E650)) is injected into the mold using an extruder, and after cooling, the mold is closed. The molded product was opened and the molded product was taken out to make a molded product with non-slip grates.The molding conditions at this time (heating cylinder temperature, mold temperature, injection pressure, molding cycle) and the state of adhesion of the non-slip tool to the molded product As shown in Table 1, it was possible to fix the anti-slip device to the molded product under the usual injection molding conditions, but when the mold temperature and heating cylinder temperature were extremely low, the result was that the anti-slip device could not be stuck. Material A of the anti-slip tool: Styrene-butadiene-styrene block copolymer (product name: CALIFLEX TR
3202, manufactured by Shell Chemical Company) B: 50/50 mixture C of styrene-isoprene-styrene type block copolymer (trade name: Caliclex TRII07, manufactured by Shell Chemical Company) and high-density polyethylene (trade name: Stafrene E650) :Polyolefin thermoplastic elastomer (product name: Somer 301G,
Comparative Examples 1 to 2 (manufactured by DuPont) Comparative Examples 1 to 2 The same procedure as Example 2 was performed except that a vulcanized rubber sheet, which will be described later, was used instead of the thermoplastic rubber sheet used as the anti-slip device in Examples 1 to 7. Shown in the table.

Although the rubber sheet was buried in the surface of the molded product, it was not heat-adhered to the high-density polyethylene and could be easily peeled off. Material of anti-slip tool a: Neoprene rubber b: Natural rubber Table 1 (Koto 1) ◎; Strongly fused and not removable at all, ○
; It is not impossible to remove it by force, but the peeling surface becomes white. △; It is adhered to some extent, but it tends to peel off in parts. 2) Under the injection molding conditions of Examples 6 and 7, even when the anti-slip village was not attached, a short shot occurred and a good molded product could not be obtained.

(Gonno 3) In practical molding, it is not possible to lower the mold temperature to less than 300m because it causes various problems (short shot, poor surface condition, etc.), and it is an impossible condition. It is.

Examples 8 to 12 When injection molding a Yu-yo seat, 150 x 10 x 1
The method shown in Fig. 2 is to hold a non-slip tool with three recesses with a diameter of 5 and a depth of 5 on the inner surface of the mold.

The material of the anti-slip tool is thermoplastic rubber and is the same as in Examples 1-7. After holding the mold, the mold is closed, and plasticized polypropylene (JHH manufactured by Mitsui Tosho Co., Ltd.) is injected and filled into the mold using an extruder. After cooling, the mold is opened and the molded product is taken out. I made a molded product for the seat. Table 2 shows the molding conditions and the state of adhesion of the anti-slip tool to the molded product. Comparative Examples 3-4 Examples 8-1
Examples 8 to 12 except that the anti-slip tool made of vulcanized rubber used in Comparative Examples 1-2 was used instead of the anti-slip tool made of thermoplastic rubber used as the anti-slip tool in Comparative Examples 1-2.
The results are shown in Table 2.

Table 2 As shown in Table 2, if the material of the molded product is polypropylene, if it is molded under the injection conditions normally used, the anti-slip device made of the molded product and thermoplastic rubber will be perfectly stable. However, in the case of vulcanized rubber, it was not thermally fused to polypropylene and could not be fixed at all.

[Brief explanation of the drawing]

FIGS. 1 and 2 are schematic views of the anti-slip device held on the inner surface of the mold, and FIG. 3 is a molded product with the anti-slip device obtained by the present invention. 1, 1': Mold, 2: Anti-slip tool, 3: Pin, 4: Resin runner, 5: Resin. ↑Figure 2Figure 3

Claims (1)

[Scope of Claims] 1. When manufacturing a molded article with anti-slip using thermoplastic resin as a raw material, a non-slip tool made of thermoplastic rubber or a mixture of thermoplastic rubber and thermoplastic resin is attached to the inner surface of the mold in advance. After placing the molten thermoplastic resin at the required location, the molten thermoplastic resin is introduced into the mold to form the molten thermoplastic resin layer, and the molten thermoplastic resin layer is heat fused and molded integrally with the anti-slip device. Method for manufacturing plastic resin molded products. 2. The method according to claim 1, characterized in that high-density polyethylene is used as a thermoplastic resin as a raw material for the molded product, and thermoplastic rubber of styrene-butadiene block copolymer is used as a material for the anti-slip device. A method for manufacturing a thermoplastic resin molded product with anti-slip properties. 3. A patent claim characterized in that high-density polyethylene is used as the thermoplastic resin as a raw material for the molded product, and a mixture of thermoplastic rubber of styrene-butadiene block copolymer and high-density polyethylene is used as the material for the anti-slip tool. A method for producing a thermoplastic resin molded article with anti-slip according to item 1. 4. Claims 1 and 2, characterized in that the anti-slip device is bonded to a required location on the inner surface of a mold using a cyanoacrylate adhesive that deteriorates at high temperatures and loses adhesive strength. Or the method for manufacturing a thermoplastic resin molded article with anti-slip according to item 3. 5. A patent claim characterized in that the anti-slip device is attached to a mold by making a recess in advance in the anti-slip device and providing pins that can fit into the recess at required locations on the inner surface of the mold. Range 1, 2 or 3
A method for producing a thermoplastic resin molded article with anti-slip properties as described in .