JP6941266B2 - Foam blow molded article, foam blow molding device, and foam blow molding method - Google Patents

Description

The present invention relates to a foam blow molded article used for an automobile air-conditioning duct or the like, and more particularly to a novel foam blow molded article in which a solid layer is partially formed for the purpose of reinforcement or the like. Further, the present invention relates to a foam blow molding apparatus and a foam blow molding method.

For example, as a method for manufacturing an automobile duct for ventilating air from an air conditioner, foam blow molding, in which a foamed molten resin is molded by molding with a split mold, is widely adopted. In foam blow molding, various types of ducts can be easily molded, and lightweight and complicated ducts can be mass-produced.

Further, in the above-mentioned foam blow molding, a hollow molded product is also blow molded from a multilayer parison in which resins having different functions are stacked for the purpose of functionality and aesthetics (for example, Patent Document 1 and Patent). Refer to Reference 2 etc.).

Patent Document 1 discloses a multi-layer foam blow molding method including a skin and a foam layer, and the molded product including the skin and the foam layer is composed of an inner layer as a base material, an outer skin, and a foam layer in between. It is stated that it will be done.

Patent Document 2 discloses a method of manufacturing an armrest by a hollow molding method, and a part of the parison may be a multilayer composed of a parison base layer and an outer layer of a different color or a different color from the base layer. Have been described.

Japanese Unexamined Patent Publication No. 6-285964338322 Special Fair 3-59814 Gazette

However, as described in Patent Document 1, when a foamed resin is used on the inside and another resin layer (non-foamed solid layer) is provided as a skin layer by covering the entire outside, the skin which is an outer layer in the mold is provided. There is a problem that a blow pressure is applied to the foamed resin layer sandwiched between the layers, bubbles are ruptured, and the weight of the molded product is increased. In a molded product including an epidermis and an effervescent layer, defoaming of air bubbles in the effervescent layer is not preferable in terms of heat insulation, soundproofing, etc., in addition to weight reduction.

In the method described in Patent Document 2, since the base layer is a non-foaming layer and the outer layer is a foaming layer, such a problem does not occur, but the base layer which is the main body of the molded product is a non-foaming layer. Therefore, it is disadvantageous in terms of weight reduction and the like. Further, even if the substrate layer is a foamed layer and the outer layer is a non-foamed layer, a problem may occur in terms of moldability. For example, in the method described in Patent Document 2, the outer layer is partially formed in the circumferential direction of the parison, but is continuous in the longitudinal direction (extrusion direction) of the parison, and the substrate layer is placed in this direction. You will be restrained. This may cause inconvenience in moldability.

The present invention has been proposed in view of such conventional circumstances, and it is possible to impart a layer having a different function to a necessary portion without causing molding defects due to foaming or restraint of the foamed layer. It is an object of the present invention to provide a possible foam blow molded article, and further, it is an object of the present invention to provide a foam blow molding apparatus and a foam blow molding method.

In order to achieve the above-mentioned object, the foam blow molding apparatus of the present invention includes an accumulator for supplying a parison made of a molten resin and a pair of molds for sandwiching and shaping the parison, and the accumulator is melt-foamed. It is composed of a main accumulator that supplies a parison made of resin and a side accumulator that intermittently supplies molten resin to the parison made of molten foam resin and imparts a layer made of molten non-foamed resin in an island shape. It is characterized by being done.

Further, the foam blow molding method of the present invention is a foam blow molding method in which a parison made of a molten resin is supplied and the parison is sandwiched between a pair of molds to form a shape, and the parison made of a molten foam resin is supplied. At the same time, the molten resin is intermittently supplied to the parison made of the molten foam resin, and a layer made of the molten non-foamed resin is imparted in an island shape.

The island-shaped solid layer is not continuously extended in either the longitudinal direction or the circumferential direction of the molded body (parison), and restrains the cylindrical foamed parison (parison made of molten foam resin) at the time of molding. There is nothing to do. Therefore, foam breakage due to blow pressure in the foamed resin layer and molding defects do not occur. Further, by adding an island-shaped solid layer, the necessary portion can be reliably reinforced.

According to the present invention, it is possible to impart a layer having a different function (for example, a reinforcing layer) to a necessary portion without causing foaming failure or molding defects due to restraint of the foamed layer. As a result, it is possible to provide a high-quality foam blow molded article that is lightweight and has sufficient functions added to the necessary parts.

It is a schematic perspective view which shows an example of the foam blow molded article. It is a cross-sectional view of the foam blow molded article shown in FIG. 1, (A) is a cross-sectional view taken along the line XX of FIG. 1, and (B) is a cross-sectional view taken along the line YY of FIG. It is a schematic perspective view which shows an example applied to an air conditioning duct. It is an enlarged view showing the vicinity of the reinforcing rib forming part of an air-conditioning duct, (A) is a schematic perspective view of a main part, (B) is a cross-sectional view of A1-A1 line, and (C) is a cross-sectional view of A2-A2 line. Is. It is an enlarged view showing the vicinity of the flange part of an air conditioning duct, (A) is a schematic perspective view of a main part, (B) is a cross-sectional view on the B1-B1 line, and (C) is a cross-sectional view on the B2-B line. .. It is a schematic perspective view of the main part which shows an example applied to an oil filler pipe. FIG. 6 is a schematic cross-sectional view of the oil filler pipe shown in FIG. It is a figure which shows an example of the foam blow molding apparatus schematically. It is a figure which shows the structural example of the accumulator. It is a figure which shows typically the state of giving a solid layer to a parison.

Hereinafter, embodiments of a foam blow molded article, a foam blow molding apparatus, and a foam blow molding method to which the present invention is applied will be described in detail with reference to the drawings.

1 and 2 show an example of a foam blow molded article to which the present invention is applied. The foam blow molded product 1 of the present embodiment is mainly composed of a tubular foam molded product main body 11, and an island-shaped solid layer 12 is formed on the surface thereof.

Here, the foam-molded body 11 is molded by, for example, blow-molding a thermoplastic resin mixed with a foaming agent. The thermoplastic resin to be used is optional, and examples thereof include polypropylene-based resins, in which 1 to 20% by mass of polyolefin-based polymer and 5 to 40% by mass of hydrogenated styrene-based thermoplastic elastomer are mixed. It is also possible to use a blended resin or the like. In particular, in order to improve the foamability, it is desirable to add a polyolefin having a long-chain branched structure as a resin material. Specific examples of the long-chain branched polyolefin include, for example, component A, component B, and component C, the component A being long-chain branched homopolypropylene, and the component B being block polypropylene (long). It may have a chain-branched structure, but it is not limited to this), and the component C is a polyethylene-based elastomer, a foam molding resin, or the like. Preferably, when the total of the components A to C is 100 parts by mass, the content of the component A is 20 to 70 parts by mass, the content of the component B is 20 to 70 parts by mass, and the component is The content of C is 1 to 20 parts by mass. Further, a resin obtained by mixing high-density polyethylene and low-density polyethylene having a long-chain branched structure may be used.

Examples of the foaming agent include a physical foaming agent, a chemical foaming agent and a mixture thereof. Examples of the physical foaming agent include inorganic physical foaming agents such as air, carbon dioxide, nitrogen gas, and water, organic physical foaming agents such as butane, pentane, hexane, dichloromethane, and dichloroethane, and their supercritical fluids. Can be applied. As the supercritical fluid, it is preferable to use carbon dioxide, nitrogen, etc., for nitrogen, the critical temperature is -149.1 ° C, the critical pressure is 3.4 MPa or more, and for carbon dioxide, the critical temperature is 31 ° C, the critical pressure. It can be made by setting it to 7.4 MPa or more.

The foaming ratio of the foamed molded body 11 formed by blow molding is arbitrary, and is composed of a closed cell structure having a plurality of cell cells (with a closed cell ratio of, for example, 70% or more). The average cell diameter of the cell in the thickness direction is, for example, less than 300 μm, preferably less than 100 μm.

The advantage of the foamed resin used for the foamed molded body 11 is that it has low specific gravity and heat conduction. Taking advantage of these advantages, it is used in various molded products aiming at weight reduction and high heat insulation effect. On the other hand, foamed resin has low mechanical strength and cannot be used in places where a load is applied.

Therefore, in the foam blow molded product 1 of the present embodiment, the solid layer 12 is provided in the portion of the foam molded product main body 11 where strength is required. The solid layer 12 is a resin layer made of a non-foaming resin, and has sufficient mechanical strength as compared with the foamed resin.

The resin material used for the solid layer 12 is arbitrary, but unlike the foam molded body 11, it is not necessary to add the polyolefin having a long-chain branched structure, and the polyolefin does not have a cheaper long-chain branched structure due to the manufacturing cost. It is desirable to use.

The foam molded body 11 and the solid layer 12 are preferably formed of the same type of material. For example, when the foam molded body 11 is made of long-chain branched polypropylene, it is desirable that the solid layer 12 is made of polypropylene. Alternatively, when the foam molded body 11 is made of long-chain branched polyethylene, it is desirable that the solid layer 12 is made of polyethylene. By using the same type of material for the foamed molded body 11 and the solid layer 12, the adhesiveness between the foamed molded body 11 and the solid layer 12 is improved, and the melting points of the resins are the same, so that during molding. In addition to facilitating the adjustment of the resin heating temperature in the above, the timing at which the molten resin is cooled by the mold and solidified can be adjusted, so that deformation of the molded product is suppressed.

However, if the solid layer 12 is continuously provided on the surface of the foamed molded body 11, the solid layer 12 restrains the foamed molded body 11, hinders foaming, causes foam breakage, and adversely affects moldability. May give. Therefore, in the foam blow molded article 1 of the present embodiment, the solid layer 12 is formed into an island shape (here, a rectangular shape) so that such a problem does not occur. Here, the island shape means a state in which the foamed molded body 11 is not continuously extended in either the longitudinal direction or the circumferential direction. As shown in FIGS. 2A and 2B, the solid layer 12 is formed with predetermined dimensions in both the circumferential direction and the longitudinal direction of the foam molded body 11, and is continuously extended. No.

Since most of the foam blow molded product 1 having such a configuration (foam molded product main body 2) is composed of a single foamed resin layer, the lightweight effect is maintained. Further, although the solid layer 12 is added to the required portion to form a partially multilayer structure, the mechanical strength can be significantly improved at the portion where the solid layer 12 is formed as compared with the surroundings.

FIG. 3 shows an example of a duct 2 to which the present invention is applied. As shown in FIG. 3, the duct 2 is mainly composed of a tubular molded body 21 that serves as an air flow path, and has an opening for connecting to another duct or the like, an opening that serves as an outlet, or the like. Has an opening 22 of. The molded body 21 which is the main body of the duct 2 is made of foamed resin for weight reduction, soundproofing, and the like, but its strength is insufficient in a portion affected by an external force. Therefore, a solid layer is formed in an island shape in the portion to increase the strength of this portion.

Specifically, in the duct 2, the rib 23 for improving the strength is formed, and the flange portion 24 for external mounting is formed. The portion where the rib 23 and the flange portion 24 are formed is a portion of the duct 2 that requires special strength. Therefore, in the present embodiment, the solid layer 25 is formed in the vicinity of the ribs 23 and the flange portions 24.

FIG. 4 shows the vicinity of the rib 23 formed in the duct 2. The rib 23 is formed by recessing the upper surface of the tubular molded body 21, and the tip surface thereof abuts on the inner wall surface on the opposite side to improve the mechanical strength. As shown in FIGS. 4A to 4C, the solid layer 25 is formed so as to be laminated on the surface of the rib 23 and its periphery.

Further, FIG. 5 shows a flange portion 24 formed in the duct 2. As shown in FIG. 5A, the flange portion 24 is formed so as to protrude from the molded body 21 by compressing the foamed resin when molding the molded body 21, and the duct is formed by attaching and fixing the flange portion 24. 2 is fixed. Therefore, the flange portion 24 is also required to have mechanical strength. Therefore, as shown in FIGS. 5A to 5C, the solid layer 25 is formed so as to cover the surface of the flange portion 24.

In the duct 2, a solid layer 25 is provided as a reinforcement of a portion affected by an external force. For example, by providing a solid layer on the screw cap portion of the oil filler pipe to form a partial multi-layer structure, the rotational torque of the cap is improved. It is also possible to improve the shape transferability of the screw portion.

6 and 7 show the vicinity of the screw cap portion of the oil filler pipe 26. The oil filler pipe 26 is composed of a pipe body 27 and a screw cap portion 28 formed at the tip thereof. A screw thread is formed in the screw cap portion 28, and as described above, improvement of the rotational torque of the cap, improvement of the shape transferability of the screw portion, and the like are required. Therefore, in the oil filler pipe 26 of the present embodiment, a solid layer 29 is provided on the surface of the screw cap portion 28 to form a partial multilayer. In this embodiment, the solid layer 29 is continuous in the circumferential direction of the screw cap portion 28, but when viewed from the entire molded body (the entire oil filler pipe 26), it is formed in an island shape.

In addition, it is useful to form the solid layer in an island shape even in a product such as a foot duct to which a load is locally applied.

Next, a molding apparatus and a molding method for a foam blow molded article having the above-described configuration will be described.

In foam molding of extruded resin such as blow molding, bubbles grow at the moment when the pressure around the resin drops sharply, so it is necessary to maintain the pressure in the resin flow path until just before the injection of the molten resin. Therefore, it is said that it is difficult to make multiple layers in foam extrusion molding.

In addition, a multi-layer foam molded product made of a sheet has already been adopted in many fields, but in the manufacturing method, it is necessary to hold the sheet outside the cavity of the mold, so that the molded product always has an outer layer that crosses the sheet. Will be provided, and the effect of weight reduction cannot be sufficiently obtained. The variation in the location of the outer layer also increases. Furthermore, sheet molding cannot be recycled in-process due to its manufacturing method.

Alternatively, for example, a method of attaching urethane to a blow molded product is also adopted, but it needs to be removed and separated at the time of recycling, which leads to loss of members and manufacturing tact.

In the molding apparatus and molding method for the foam blow molded article of the present invention, molding to partially form a solid layer was realized by using the ring accumulator and the second extruder in combination.

FIG. 8 shows a schematic configuration of a foam blow molding apparatus, which is basically composed of an extruder (accumulator) 31 and a pair of dies 32 and 33 for shaping the extruder (accumulator) 31. At the time of molding, a parison P made of molten resin extruded from an extruder 31 is sandwiched between a pair of dies 32 and 33 to form a shape, and this is taken out from the dies 32 and 33 to obtain a foam blow molded article.

Here, as shown in FIG. 9, the extruder 31 includes a main accumulator 40 that supplies the molten foam resin, and a side accumulator 50 that adds the molten resin for forming a solid layer from the side surface to the parison P. ..

The main accumulator 40 is configured to have an annular die 41 and a core 42 arranged in the center thereof, and the molten resin passes through an annular slit 43 between the die 41 and the core 42 to form a circle. The annular parison P is extruded. Here, the wall thickness of the parison can be adjusted by adjusting the distance between the annular slit 43 between the die 41 and the core 42.

The side accumulator 50 includes an extruder 51 for supplying molten resin for forming a solid layer, and the resin charged from the inlet 52 is melt-kneaded in a cylinder 53 provided with a screw, and the side accumulator 50 is melt-kneaded. Is supplied to. In the side accumulator 50, the molten resin for forming the solid layer is intermittently applied to the surface of the parison P.

FIG. 10 schematically shows a state in which the resin S for forming a solid layer is applied to the parison P. By intermittently supplying the solid layer forming resin S from the side accumulator 50, the solid layer is formed on the surface of the parison P in a state where it is not continuous in either the circumferential direction or the extrusion direction (longitudinal direction) of the parison P. The resin S can be applied in an island shape. By molding the parison P to which the island-shaped solid layer forming resin S is applied on the surface in the molds 32 and 33 in this way, it is possible to form a foam blow molded product in which the island-shaped solid layer is formed. can.

In the above-mentioned molding apparatus and molding method for the foam blow molded product, only the portion to which the function is to be imparted can be pinpointed in multiple layers, and foam rupture, foam failure, etc. in the foamed resin as the base material can be suppressed. In addition, the weight can be reduced as compared with the molded body having a multi-layered structure as a whole. Further, by making only the portion to which the function is to be imparted into multiple layers, the manufacturing cost can be suppressed as compared with the molded body having multiple layers in the whole or in the circumferential direction or the longitudinal direction.

Furthermore, the molding apparatus and molding method for the foam blow molded article of the present invention have an advantage that they can be recycled in the manufacturing process and do not require sorting.

Although the embodiments to which the present invention is applied have been described above, it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. It is possible.

1 Foam blow molded body 11 Foam molded body body 12 Solid layer 2 Duct 21 Molded body 22 Opening 23 Rib 24 Flange part 25 Solid layer 26 Oil filler pipe 27 Pipe body 28 Screw cap part 29 Solid layer 31 Extruder 40 Main accumulator 41 Die 42 Core 43 Circular slit 50 Side accumulator 51 Extruder 52 Input port 53 Cylinder P Parison S Solid layer forming resin

Claims (2)

It is equipped with an accumulator that supplies a parison made of molten resin and a pair of molds that sandwich and shape the parison.
The accumulator intermittently supplies the molten resin to the main accumulator that supplies the parison made of the molten foam resin and the parison made of the molten foam resin, and imparts a layer made of the molten non-foamed resin in an island shape. A foam blow molding apparatus characterized by being composed of a side accumulator. A foam blow molding method in which a parison made of molten resin is supplied and the parison is sandwiched between a pair of molds to form a shape.
It is characterized in that a parison made of a molten foam resin is supplied, and a molten resin is intermittently supplied to the parison made of the molten foam resin to impart a layer made of a molten non-foamed resin in an island shape. Foam blow molding method.

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