JP2002160224A - Mold for producing lightweight thermoplastic resin article and method for producing lightweight thermoplastic resin article using the same - Google Patents

Abstract

[PROBLEMS] A thermoplastic resin lightweight molding which has a high expansion ratio, a foaming ratio or a high hollow ratio, and which can easily produce a lightweight thermoplastic resin molding having excellent surface transfer properties. Develop molds for body production. In a mold comprising a pair of male and female having at least one vacuum suction port opened to a molding surface of one or both of the male and female molds, at least one vacuum suction port is continuously surrounded. Protrusions or grooves are provided on the molding surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for producing a lightweight thermoplastic resin article and a method for producing a lightweight thermoplastic resin article using the same.

[0002]

2. Description of the Related Art Conventionally, a mold comprising a pair of male and female having a vacuum suction port on a molding surface of one or both male and female molds is well known. For example, Japanese Patent Application Laid-Open No. 7-9461 discloses a female mold. Using a mold comprising a pair of male and female having a vacuum suction port on the molding surface of at least one mold of the mold or the male mold,
The foaming thermoplastic resin is supplied and filled into the cavity of the mold in a molten state, and after forming a surface layer of the molded body along the mold surface, the mold is opened while vacuum suctioning the surface layer. Discloses a method for producing a foamed thermoplastic resin article by increasing the cavity volume.

However, in the mold disclosed in this method, the force of adsorbing the surface layer to the molding surface of the mold is weak, and the molding surface shrinks due to solidification of the molten resin at the time of molding and the like. Since the molding surface is easily separated from the molding surface and the cavity volume cannot be increased at a high speed, there is a problem that a high-magnification foam molded product cannot be obtained or good mold transferability is hardly obtained.

[0004]

SUMMARY OF THE INVENTION
The present inventor has solved the above problem, and as a result of studying to produce a thermoplastic resin light-weight molded article having excellent mold transferability, the present invention has been achieved.

[0005]

That is, the first aspect of the present invention is as follows.
In a mold consisting of a pair of male and female having at least one vacuum suction port that opens to the molding surface of one or both of the male and female molds, protrusions or so as to continuously surround the periphery of at least one vacuum suction port. It is intended to provide a mold for manufacturing a lightweight molded article of a thermoplastic resin, in which a groove is provided on a molding surface, and a second aspect of the present invention uses such a mold,
(A) a step of supplying a molten thermoplastic resin between both molds and filling the thermoplastic resin into a mold cavity; (b) a part or all of the mold while vacuum-sucking from the mold molding surface In the thickness direction of the molded article, and (c) cooling the molded article while maintaining the cavity clearance at the final thickness of the molded article.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below.
The following description is an example of the present invention, and the present invention is not limited thereto.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a mold for producing a thermoplastic resin lightweight molded body according to the present invention comprises a male and female pair of a male mold (7) and a female mold (6). The mold surface is provided with a vacuum suction port (11) that opens into the cavity. Normally, one of the two dies is connected to a press device to move, and the other is fixed and can be opened and closed in the vertical or horizontal direction. (In the figure, the male mold is fixed and the female mold is movable so that it can be opened and closed in the vertical direction.)

In such a mold, the vacuum suction port (1
1) is connected to a suction device such as a vacuum pump (not shown) via a suction path. The suction path may be provided with an opening / closing valve that can control suction and stop arbitrarily, and may be provided with a control mechanism for adjusting the suction force as needed.

The vacuum suction port (11) needs to be opened in the molding surface of the mold. However, the vacuum suction port (11) should be opened so that the molten thermoplastic resin supplied into the cavity does not enter the opening. The part may be formed by a plurality of fine holes, may use a gap between joints of members constituting the mold generally called a score line, or the mold may be partially or substantially It may be composed entirely of a porous metal having air permeability.

[0010] A projection (24) or a groove (24) is provided on the mold molding surface where the vacuum suction port (11) is open so as to continuously surround the periphery of at least one vacuum suction port. .

When the projections (24) are provided, their cross-sectional shapes are square, rectangular, and rectangular as shown in several examples in FIG.
It is arbitrary such as trapezoid, triangle, semicircle, semi-ellipse, etc., and in some cases, it is not particularly limited to the shape such as a shape obtained by combining these shapes. It is appropriately selected in terms of the type, metal workability, and the like.

The size of the projection (24) is not particularly limited.
The size and shape of the molded body are appropriately determined depending on the thickness of the product, but in any shape, the height is preferably equal to or larger than the base, and the size of the base is generally Is preferably about 0.5 to 10 mm.

The position at which the projection (24) is provided is appropriately determined by the size and shape of the molded body, the position at which a vacuum suction port is provided, or a portion that does not require vacuum suction.
It is necessary to provide the projection such that at least one vacuum suction port is located in the molding surface continuously surrounded by the projection. When it is desired to suction almost the entire surface of the product, it is preferable to provide the product at a position along the outer periphery or near the outer periphery of the target formed body as much as possible as shown in the left diagram of FIG. As shown in the right diagram of FIG. 3, only the relevant portion needs to be surrounded by continuous projections.

The number of projections surrounding the vacuum suction port is not limited to one.
A plurality of double or triple may be provided, and in such a case, a sufficient effect can be obtained even if each projection is small.
When a plurality of protrusions are provided, the cross-sectional shapes of the protrusions may be the same or different, and the heights and bases may be different from each other.

The region surrounded by the projection (24) is not limited to one, and a plurality of regions may be provided as shown in the right diagram of FIG. 3, or one region surrounded by the projection as shown in the left diagram of FIG. Another region surrounded by other protrusions may exist in one region, and the region surrounded by the protrusions may be divided into a plurality of regions as shown in the center view of FIG.

If there is a portion that is not desired to be vacuum-sucked, a region surrounded by other projections is formed in a region surrounded by the projections, for example, as shown in the right diagram of FIG. By not providing a vacuum suction port in a region where vacuum suction is not desired, it is possible to partially create a portion where vacuum suction is not performed.

As described above, by providing the projection that continuously surrounds the periphery of at least one vacuum suction port, when vacuum suction is performed, the projection prevents vacuum leakage, and the skin layer is more reliably formed in the mold. It is adsorbed on the molding surface and mold transferability is improved.

The above description has been made with respect to the protrusion as an example. The same applies to the groove shape. In this case, the cross-sectional shape of the protrusion is the cross-sectional shape of the groove, and the height and bottom of the protrusion are the depth and the groove width of the groove. Can be replaced with In addition, when the groove shape is provided, since the molten thermoplastic resin supplied into the cavity enters the groove portion and is integrated with the skin layer, when vacuum suction is performed from the mold molding surface, In addition, the groove-like material prevents vacuum leakage, and the same effect as in the case where the projection is provided can be obtained.

When the projections or grooves are provided on the mold molding surface, only the projections may be provided, only the grooves may be provided, or a combination of these may be provided. This is appropriately determined depending on the shape and design of the product.

In the mold of the present invention, one or both of the male and female molds may be provided with a communicating portion for communicating the inside of the cavity with the atmosphere. The communicating portion is provided with an opening (18) provided on the mold molding surface and communicating with the atmosphere.
(FIG. 1), or may be a pin-like object (20) having an opening hole (FIG. 5), and the outer peripheral portion of the mold cavity can be used as a communication portion. . (FIGS. 6 and 7)

When the opening hole (18) is provided on the mold forming surface, the opening hole can be opened to the atmosphere through an atmosphere path (19) provided in the mold. In this opening hole, open,
An on-off valve (17) capable of arbitrarily controlling the closing may be provided, and a control mechanism for adjusting the opening area thereof may be provided as needed. (Fig. 1 shows an example in which an opening with an on-off valve is provided.)

When a pin-shaped object (20) having an opening hole is used, the opening hole can be opened to the atmosphere through an air passage, and the pin-shaped object itself is driven by a driving device (21) such as an air cylinder. It can move forward and backward with respect to the mold forming surface.

In the embodiment using the outer peripheral portion of the mold cavity, after filling the molten thermoplastic resin into the cavity,
With the cavity clearance open to the final molded body thickness, the length of the sliding surfaces of both dies is reduced so that the engagement portion of the sliding surfaces (22) of the male and female dies is eliminated, and the cavity and the atmosphere are removed. Is desirably communicated with the portion where the engagement is lost. (FIG. 7) In this case, the gap between the sliding surfaces is preferably set to about 0.05 to 1 mm.

In the case of a butting type having no sliding surface,
After filling the cavity with the molten thermoplastic resin, a slight opening of the mold creates a gap between the two molds that have been in the abutting state, allowing the atmosphere to communicate with the atmosphere. (FIG. 6)

Such a communicating portion between the inside of the cavity and the atmosphere needs to be provided in a portion other than the region surrounded by the projection and being sucked.

The method of supplying the molten thermoplastic resin into the mold cavity is arbitrary, but a resin supply port (10) for supplying the molten thermoplastic resin is formed by molding either or both male and female molds. The resin supply port (10) is advantageously provided on the surface (in each figure, provided on the male molding surface). In such a case, the resin supply port (10) is provided through a resin supply path (9). 8). The number of resin supply ports is not limited to one, and two or more may be provided as necessary. The number and positions of the resin supply ports are appropriately selected depending on the shape of the molded body, the type of the thermoplastic resin to be used, and the like, and the resin supply path near each resin supply port has an arbitrarily controllable on-off valve. May be provided so that the supply and stop of the molten resin stored in a resin supply device such as an injection machine can be arbitrarily controlled.

The thermoplastic resin lightweight molded articles obtained by using the above-mentioned molds can be roughly classified into three types: fiber reinforced thermoplastic resin expanded molded articles, thermoplastic resin foam molded articles, and thermoplastic resin hollow molded articles. The forms are exemplified, and these methods are basically the same in all methods, although the structure of the thermoplastic resin as a raw material differs depending on the desired molded article.

The fiber-reinforced thermoplastic resin expanded molded article of the first embodiment has a skin layer (1) which is an outermost layer having almost no voids, and an inflatable layer (2) having voids between both skin layers.
And a skin material (16) may be further laminated on the surface of the skin layer as necessary. In the expansion layer, the reinforcing fibers are intricately entangled with each other, and preferably have a beam structure fixed by a thermoplastic resin near the contact point. It is preferable that the average length of the reinforcing fibers therein is 1 mm or more.

The thermoplastic resin hollow molded article of the second embodiment is composed of an outermost resin layer (27) and a hollow part (28) existing between the resin layers. A skin material may be further laminated as necessary.

The thermoplastic resin foam molded article of the third embodiment has a skin layer (25) which is an outermost layer having almost no voids.
And a foamed thermoplastic resin layer (26) having a gap between both skin layers, and a skin material may be further laminated on the surface of the skin layer as necessary.

Hereinafter, a method for manufacturing such a lightweight thermoplastic resin molded article will be described. In the production of the fiber-reinforced thermoplastic resin expansion molded article of the first embodiment, a thermoplastic resin containing a reinforcing fiber is used as a raw material. The reinforcing fiber in the molded product has an average fiber length of 1 mm.
In order to maintain the above, the average fiber length was 3 as the raw material resin.
It is preferable to use a thermoplastic resin containing reinforcing fibers of not less than mm. Here, the weight average fiber length which is a general index is used as the average fiber length.

The average fiber length of the reinforcing fibers in the molded product is 1 mm
As a method of supplying the molten thermoplastic resin containing the reinforcing fiber into the mold cavity as held above, for example, a reinforcing fiber having an average fiber length of 3 mm or more and a granular or pellet-like thermoplastic resin, for example, A method of supplying a molten resin obtained by melt-kneading in an injection machine having an in-line screw into a cavity, or a thermoplastic resin material containing a reinforcing fiber having an average fiber length of 3 mm or more formed in advance, for example, a long fiber reinforced material A method in which a molten resin obtained by melting and kneading thermoplastic resin pellets is supplied into the cavity is exemplified.

In the latter case, as long fiber reinforced thermoplastic resin pellets, for example, a glass roving impregnated with a molten thermoplastic resin, cooled and solidified is cut into a suitable length, for example, about 3 to 25 mm. Pellets made of such are preferably used. Such long-fiber thermoplastic resin pellets may be used alone or may be used in combination with a thermoplastic resin comprising a matrix resin of the pellets for adjusting the reinforcing fiber content, and in some cases, It may be mixed with another thermoplastic resin.

Here, as the reinforcing fibers, various types of reinforcing fibers conventionally known as reinforcing fibers, such as glass fibers, carbon fibers, and alumina fibers, are used, and glass fibers are most commonly used. Is done.

As the thermoplastic resin, any thermoplastic resin used for extrusion molding, injection molding, press molding and the like can be used.
Polypropylene, polystyrene, acrylonitrile / styrene copolymer, acrylonitrile / styrene / butadiene copolymer, styrene / methyl methacrylate copolymer, polyvinyl chloride, polyamide, polycarbonate,
General thermoplastic resins such as polyethylene terephthalate, thermoplastic elastomers such as ethylene-propylene-diene copolymer, mixtures thereof or polymer alloys using them, and the like, and the thermoplastic resin referred to in the present invention are Are all included. Such a thermoplastic resin may contain a filler such as talc, if necessary, and of course, various commonly used additives such as a pigment, a lubricant, an antistatic agent, and a stabilizer are appropriately compounded. May be.

It should be noted that, as the reinforcing fibers have better adhesion to the thermoplastic resin as the matrix, the bonding between the fibers via the matrix resin becomes stronger, and the strength of the obtained molded article is also improved. For example, when the matrix resin is a polypropylene-based resin and the reinforcing fiber is a combination of glass fibers, it is not possible to perform a surface treatment on the glass fibers or mix a modifier with the thermoplastic resin to improve the adhesion. It is valid.

In the reinforcing fiber-containing thermoplastic resin as a raw material, the content of the reinforcing fibers in the reinforcing fiber-containing thermoplastic resin composition varies depending on the desired degree of expansion of the expanded molded article, desired properties, and the like. Generally, it is in the range of 10 to 80% by weight.

In the production of such an expanded molded article of a thermoplastic resin-containing thermoplastic resin, a molten resin containing a reinforcing fiber as a base material is supplied and filled between the male and female dies. (Step a). The temperature of the molten resin to be supplied varies depending on the type of the thermoplastic resin to be used, the molding conditions, the type of the skin material when the skin material is bonded, and the like, and the optimal temperature is appropriately set. When using a glass fiber reinforced thermoplastic resin having a resin matrix,
The temperature is 70 to 300 ° C, preferably 200 to 280 ° C.

The filling of the molten resin (12) containing the reinforcing fibers into the mold cavity may be carried out by an injection filling method or by a method of clamping both molds. It is appropriately selected depending on the form.

As a method by injection filling, supply of a molten thermoplastic resin containing reinforcing fibers is started in a state where both molds are positioned so as to have a cavity clearance smaller than the thickness of the molded body before expansion (FIG. 8) The mold is opened while the molten resin is being supplied, and at the same time when the supply of the molten resin is completed, the cavity is filled into the cavity so that the cavity clearance matches the thickness of the molded body before expansion (FIG. 9). An example is a method in which the molten resin is supplied in a state where both molds are positioned so as to have the same cavity clearance as the thickness of the previous molded body, and the molten resin is supplied and filled into the cavity. (FIG. 9
Same as)

When the supply of the molten resin is started in a state where both molds are positioned so that the former cavity clearance is smaller than the thickness of the molded body before expansion, the cavity clearance at the start of the supply is determined by the cavity at that time. The volume is usually 5 to the volume of the required amount of molten resin before expansion.
Not less than 100% by volume, preferably 30% by volume
As described above, the range is 70% by volume or less.

When the supply of the molten resin is started in such a state, as the supply of the molten resin proceeds, the movable mold retreats, the cavity clearance is enlarged, and the supply of the required amount of the molten resin is completed. The volume of the supplied molten resin is substantially equal to the volume of the cavity, and the cavity is filled with the molten resin.

At this time, the expansion of the cavity clearance may be controlled by mechanically retracting the die by a press device or the like attached to the die, or may be expanded by utilizing the supply pressure of the molten resin to be supplied. However, at this time, it is desirable to control the pressure applied to the resin to be about 1 to 50 MPa. In addition, in the process of expanding the cavity clearance, it is necessary to take care that the cavity volume does not become larger than the volume of the supplied molten resin.
If the time is short, there is no particular problem even if the volume of the mold cavity becomes larger than the volume of the supplied molten resin.

In the latter method, the molten resin is supplied in a state where both molds are positioned so as to have the same cavity clearance as the thickness of the molded body before expansion, and the molten resin is filled in the mold cavity. As in the molding method, the cavity clearance of the mold may be maintained from the start of the supply of the molten resin to the completion of the supply so as to be the same as the thickness of the molded body before expansion.

When the cavity is filled with the molten resin by the mold clamping operation of both dies, both dies are required to be opened in the mold cavity so that the cavity clearance is equal to or greater than the thickness of the molded body before expansion. An amount of the molten resin (12) is supplied (FIG. 13), and after completion of the supply or simultaneously with the completion of the supply, the mold is clamped and filled so that the cavity clearance becomes the same as the thickness of the molded body before expansion (FIG. 14). However, in this method, the mold clamping is started during the supply of the molten resin, and while the supply of the molten resin and the mold clamping are performed in parallel, the cavity clearance is not expanded at the same time as or after the completion of the supply of the molten resin. May be the same as the thickness of the molded body. (Note that FIGS. 13 and 14 show examples in which the skin material is bonded, but the die operation is the same when the skin material is not bonded.)

Of these methods, when injection molding is used, a molded article having a better surface appearance can be obtained as the cavity clearance during the supply of the molten resin is reduced. Since the breakage of the reinforcing fibers tends to increase, the cavity clearance is appropriately determined depending on the thickness, size, shape, and the like of the molded body. On the other hand, in the method of filling by clamping both molds, since the pressure applied to the supplied molten resin is reduced,
Breakage of the reinforcing fibers in the molten resin can be minimized, and a decrease in expandability and a decrease in strength can be prevented.
For this reason, the injection molding method is generally advantageous when emphasizing the appearance of the expanded molded article, and the mold filling method is advantageous when emphasizing the expandability and strength.

The mold cavity filled with the molten resin by such a method has little or no gap in some cases.
In this state, the skin layer (1) is formed on the surface of the molten resin in contact with the molding surface of the mold. However, since the mold temperature is generally set lower than that of the molten resin, an appropriate cooling time must be provided. As a result, the molten resin starts to solidify from the surface portion in contact with the mold forming surface, and a skin layer having almost no voids is eventually formed. (FIG. 10)

The cooling time at this time greatly affects the formation of the skin layer, and the longer the cooling time, the easier the skin layer is formed and the thicker the skin layer. If the skin layer is too thick, the expansion ratio associated with the subsequent opening of the mold is reduced, and if it is too thin, the strength tends to be low. Is appropriately determined depending on the expansion ratio and strength of the molded product. Generally, the total thickness of both sides (front and back) of the skin layer is 5 to 30% of the thickness of the molded product.
The cooling time from filling the molten resin into the cavity to opening the mold in the next step depends on the mold temperature, the temperature of the supplied molten resin, the type of resin, etc. Although it depends on various conditions, it is usually 0.1 to 2
It is about 0 seconds.

In the process of forming the skin layer or after the formation of the skin layer, vacuum suction is performed through a vacuum suction port (11) provided in the mold, and the skin layer is adsorbed on the mold forming surface. At this time, the protrusions or grooves provided in the mold can prevent suction leakage between the skin layer and the mold molding surface, and the skin layer can be firmly adhered to the mold molding surface. When the mold cavity is opened in the thickness direction of the molded body while maintaining the state in which the skin layer is adsorbed on the mold molding surface (step b), the unsolidified portion of the supplied reinforcing fiber-containing molten resin is obtained. Expands due to the restoring force of the reinforcing fibers, and an expanded layer (2) is formed. (FIG. 11 Here, by opening the skin layer in the thickness direction of the molded body while adsorbing the skin layer on the mold molding surface, the expansion can be performed with a force larger than the restoring force of the reinforcing fiber, and the expansion molding with a higher expansion coefficient You can get the body.

In the process of forming the skin layer or in the process of opening the mold cavity in the thickness direction of the molded body after the formation of the skin layer, the inside of the cavity is brought into a state of communication with the atmosphere, and the unsolidified state in the molten resin is formed. By opening the mold while introducing the air into the portion at the above, it is possible to obtain a higher magnification expansion molded body, which is advantageous.

Here, as a method of opening the mold while introducing the air into the unsolidified portion of the molten resin, an opening hole (1) provided on the mold molding surface and communicating with the atmosphere is provided.
In the case of a method in which the inside of the cavity is communicated with the atmosphere through 8), the opening (18) is kept closed until the cavity is filled with the molten resin, and the opening is formed after the skin layer is formed. Or the opening of the mold may be started in the thickness direction of the molded body, and at the same time, the opening hole opening / closing valve may be operated to open the opening hole.

When the inside of the cavity is communicated with the atmosphere at the outer periphery of the cavity of the mold without using the opening hole, the mold is slightly opened to allow the gap between the two molds to be abutted. A gap (skin layer non-forming portion) (23) is formed in the mold (FIG. 6), or a skin layer non-forming portion (23) is formed in a portion where the sliding surfaces (22) of both dies no longer mesh with each other, The cavity is in communication with the atmosphere. (FIG. 7)

In these methods, it is difficult to introduce the air into the molded body while the skin layer is formed on the surface of the molded body, so that the skin layer near the communication portion with the atmosphere is destroyed or It is necessary to form the skin layer non-formed portion (23) so that the skin layer is not formed in the vicinity.

Therefore, for example, when the interior is in an unsolidified state, the skin layer at the point where air is desired to be introduced, that is, at the portion corresponding to the opening hole, is brought into non-contact with the mold molding surface, and the unsolidified state is obtained. The skin layer is softened by the heat of the molten resin, and the atmosphere can be introduced from the softened portion. Also, as another method, the molding surface of the portion where the skin layer is not desired to be formed is made of a material having a low thermal conductivity, or the molding surface temperature is kept partially higher than the surrounding mold molding surface, Depending on the method, a method of keeping the temperature near or above the melting point of the thermoplastic resin to be used can be adopted.

When a pin-shaped object (20) having an opening hole is used, the pin-shaped object is retracted in the mold until the cavity is filled with the molten resin. After the layer is formed thinly, the pin-shaped object can be advanced and pierced into the molded body to introduce air into the molded body. (Fig. 5)

By releasing the mold while taking in the atmosphere into the molded body, it is possible to prevent a negative pressure inside the molded body from hindering the restoring force of the reinforcing fiber and to obtain a molded body expanded at a high magnification. be able to.

In this method, when one surface of the molded article is the design surface, a vacuum suction port is provided at least on the mold molding surface on the design surface side, and the skin layer serving as the design surface is formed on the mold molding surface. It is preferable to open the mold in a state where it is adsorbed. Also, when both sides of the expansion molded body are designed surfaces,
It is preferable to provide a vacuum suction port on both mold forming surfaces and open the mold while keeping both skin layers in close contact with the mold forming surfaces.

In the opening operation of the mold, it is desirable to control the mold opening speed, the opening amount and the like by a press device attached to the mold or a mold opening device such as a hydraulic cylinder provided on the mold itself. .

The vacuum suction is generally started after the skin layer is formed on the surface of the molten thermoplastic resin containing the reinforcing fibers supplied into the cavity. Suction may be started at the stage of filling the molten thermoplastic resin, or may be started during a cooling time for forming a skin layer.

When the cavity clearance of the mold reaches the final expansion molding thickness, the mold opening operation is stopped, and the molding is cooled while maintaining this state (step c). (FIG. 11) The suction operation is preferably performed continuously until the cooling of the compact is completed.

In the above expansion operation, after filling the cavity with the molten thermoplastic resin, the cavity clearance of the mold is opened and expanded so as to be larger than the thickness of the final molded body, and then supplied. Without completely solidifying the molten resin, mold clamping to the final molded body thickness while the central part is still in a molten state at least in the thickness direction,
The compact may be cooled and the compact may be cooled while maintaining this state. In this case, the adhesiveness between the supplied molten resin and the mold forming surface can be improved, and the mold shape can be reproduced more faithfully.

When the cooling is completed, the mold is completely opened, and the fiber-reinforced thermoplastic resin expansion molded product as the final molded product is taken out. (FIG. 12)

In such a method, a fiber-reinforced thermoplastic resin expanded molded article having a partially expanded portion is manufactured by forming a die structure in which a part of the die forming surface can be partially moved. be able to.

For example, as shown in FIG. 15, a mold in which a part of the mold is a movable molding surface structural member, for example,
Slide core (14) provided with protrusions and grooves near its outer periphery
In this method, the slide core is moved in advance by a moving device such as a hydraulic cylinder (15) so that the mold forming surface can be partially moved in the opening and closing direction of the mold. The mold cavity is formed by aligning the surface with the mold molding surface, and a molten thermoplastic resin containing reinforcing fibers is supplied and filled into the mold cavity by the method described above. By moving the slide core in a direction of increasing the thickness while adsorbing on the molding surface, the expansion is formed in the portion, and by cooling, the fiber reinforced thermoplastic resin having a partially expanded portion in the portion where the slide core is provided An expanded molded article can be manufactured. (FIG. 16) In this case, the communicating portion between the inside of the cavity and the atmosphere is provided with an opening hole (1) in the slide core or a mold molding surface facing the slide core.
8) It is preferable to provide a pin-shaped object (20) having an opening hole.

In the production of such a fiber-reinforced thermoplastic resin expansion molded product, if a skin material-integrated expansion molded product having a skin material (16) bonded to part or all of its surface is desired, In the method described above, a skin material is previously supplied between the molds so as to cover part or all of the mold molding surface,
The molten thermoplastic resin 1 containing reinforcing fibers is supplied between the skin material and the molding surface of the mold according to the above method, and after filling the mold cavity, the mold is opened, cooled, and melted in the same manner as the above method. What is necessary is just to supply, fill, and cool a thermoplastic resin in a shape. At this time, depending on the skin material used, the molten thermoplastic resin 2 containing reinforcing fibers is supplied between the unclosed molds,
A method of filling the cavity by mold clamping may be preferable. (FIGS. 13 and 14)

Examples of the skin material used in this method include general thermoplastic resin or thermoplastic elastomer sheets and films, thermoplastic resin or thermoplastic elastomer foam sheets, nonwoven fabrics, fabrics, and the like, or general materials such as these. A combination is used. When the skin material is bonded, a skin layer may not be easily formed on the surface of the molten resin on the surface where the skin material is bonded. The skin material in close contact with the resin may be regarded as a skin layer and adsorbed on the molding surface.

In the above-described method, depending on the type of the thermoplastic resin used, the type of the reinforcing fiber, the filling rate of the reinforcing fiber, and the like, the formed skin layer is hardly broken and the air is hardly introduced. is there. In such a case, if the foaming agent is slightly mixed in advance into the thermoplastic resin containing the reinforcing fibers as the raw material, the skin layer is formed by the pressure at which the gas generated by the decomposition of the foaming agent is blown out of the molded body. Is effective because it is easily destroyed. When using a foaming agent for such a purpose, the amount used is based on the resin content in the thermoplastic resin containing the reinforcing fibers of the raw material,
It is about 0.01 to 5% by weight. For the same purpose,
Through the fluid injection port and resin supply port provided on the mold molding surface,
It is also possible to inject a fluid into the molded body to help break the skin layer. In this case, the fluid inlet may use an opening for introducing air. Here, examples of the fluid include a volatile liquid and a gas such as air, nitrogen, and carbon dioxide, and a gas, particularly a compressed gas such as compressed air, is preferable.

Next, a method for producing a thermoplastic resin foam molded article which is the second embodiment of the thermoplastic resin lightweight molded article will be described. In this production method, a thermoplastic resin containing a foaming agent is used as the thermoplastic resin. Otherwise, the method is basically exactly the same as the method described above. However, in this case, it is necessary to use a mold having no communication portion with the atmosphere.

The thermoplastic resin used in this method is the same as the thermoplastic resin exemplified above, and may contain various fillers and reinforcing fibers according to the purpose. The average fiber length of the reinforcing fibers to be compounded is preferably less than 1 mm, particularly preferably 0.5 mm or less.

The thermoplastic resin used here is mixed with various known organic or inorganic foaming agents. The thermoplastic resin is melt-kneaded by a known method such as an in-line type injection machine. As a result, the foaming agent is decomposed, and the decomposed gas is dispersed and confined in the molten resin. The molten thermoplastic resin in such a state is supplied into the cavity. The amount of the foaming agent used at this time varies depending on the desired expansion ratio of the foamed molded article, the type of the resin used, the type and the amount of the filler to be compounded, and the like. On the other hand, it is in the range of 0.01 to 5% by weight. In addition, the thermoplastic resin (1
The temperature 2) varies depending on the type of thermoplastic resin used, molding conditions, type of foaming agent, and the like, and the optimum temperature is appropriately set. For example, a material obtained by mixing an inorganic foaming agent with a polypropylene resin is used. If used, usually 17
The temperature is about 0 to 250 ° C, preferably about 200 to 230 ° C.

The molten thermoplastic resin containing such a foaming agent is supplied and filled into the mold cavity in the same manner as described above. In this state, a skin layer (25) is formed in the same manner as described above. During the process of forming the skin layer or after the skin layer is formed, suction is performed from the vacuum suction port in the same manner as described above, and the skin layer is adsorbed on the mold forming surface.

When the mold is opened in the thickness direction of the molded body while the state in which the skin layer is adsorbed on the molding surface of the mold, the gas trapped in the unsolidified molten resin foams, and the foamed layer is formed. (26) is formed. (FIG. 17) By opening the mold in the thickness direction of the molded body while adsorbing the skin layer to the mold molding surface by vacuum suction, the molded body can be foamed with a force larger than the foaming force due to the internal pressure of the bubbles. it can.

When the mold cavity clearance reaches the final molded product thickness, the opening operation of the mold is stopped, and the molded product is cooled while maintaining the cavity clearance at the final molded product thickness. After cooling is completed, the mold is completely opened, and the thermoplastic resin foam molded article as the final molded article is taken out of the mold. Also at this time, it is preferable to continue the suction operation until the cooling of the molded body is completed.

In the production of such a thermoplastic resin foam molded article, a partially foamed thermoplastic resin foamed article is produced in the same manner as in the case of the above-mentioned fiber reinforced thermoplastic resin expanded molded article having a partially expanded portion. A molded article can be manufactured.

As shown in FIGS. 18 to 19, a thermoplastic resin hollow molded article which is a third embodiment of the thermoplastic resin lightweight molded article is made of a thermoplastic resin containing no reinforcing fibers of long fibers or a foaming agent. Can be produced in exactly the same manner as described above except that it is used. Of course, also in this case, the manufacturing method itself is basically the same as described above.

In the case of producing such a thermoplastic resin hollow molded body, the supplied thermoplastic resin is entirely or mostly formed as an outer resin layer (27) for forming a hollow portion (28). In the latter case, a part of the thermoplastic resin may form a rib-like material in the hollow part depending on conditions. When manufacturing a thermoplastic resin hollow molded body,
When the atmosphere is introduced into the hollow portion, it is preferable that the communication portion with the atmosphere is provided on the mold molding surface.

In the case where a molded product obtained by further laminating a skin material on the surface of the above-mentioned lightweight thermoplastic resin molded product is desired,
Before supplying the molten resin, the skin material may be supplied in advance between the molds, and then the method may be performed in the same manner as described above.

[0078]

By using the mold of the present invention to manufacture a thermoplastic resin lightweight molded article such as a thermoplastic resin expanded molded article, a thermoplastic resin foam molded article, or a thermoplastic resin hollow molded article, a high expansion ratio can be obtained. It is possible to easily manufacture a lightweight thermoplastic resin molded article having excellent foaming ratio or high hollow ratio, light weight, and excellent surface transferability. The thus obtained thermoplastic lightweight molded article is a lightweight, high-strength molded article. It can be widely used for various applications such as various interior members and structural members.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a typical example of a mold of the present invention.

FIG. 2 is a cross-sectional view illustrating an example of a projection provided on a molding surface of a mold according to the present invention.

FIG. 3 shows a positional relationship between a protrusion and a vacuum suction port in the mold of the present invention. The upper part is a plan view on the molding surface side, and the lower part is a sectional view of the mold. It is.

FIG. 4 shows the positional relationship between the protrusions and the vacuum suction port in the mold of the present invention. The upper part is a plan view on the molding surface side, and the lower part is a sectional view of the mold. It is.

FIG. 5 is a schematic cross-sectional view of a mold showing manufacturing steps in the method of the present invention.

FIG. 6 is a schematic sectional view of a mold showing manufacturing steps in the method of the present invention.

FIG. 7 is a schematic cross-sectional view of a mold showing manufacturing steps in the method of the present invention.

FIG. 8 is a schematic cross-sectional view of a mold showing manufacturing steps in the method of the present invention.

FIG. 9 is a schematic cross-sectional view of a mold showing manufacturing steps in the method of the present invention.

FIG. 10 is a schematic cross-sectional view of a mold showing manufacturing steps in the method of the present invention.

FIG. 11 is a schematic cross-sectional view of a mold showing manufacturing steps in the method of the present invention.

FIG. 12 is a schematic cross-sectional view of a mold showing manufacturing steps in the method of the present invention.

FIG. 13 is a schematic cross-sectional view of a mold showing manufacturing steps in the method of the present invention.

FIG. 14 is a schematic cross-sectional view of a mold showing manufacturing steps in the method of the present invention.

FIG. 15 is a schematic cross-sectional view of a mold showing manufacturing steps in the method of the present invention.

FIG. 16 is a schematic cross-sectional view of a mold showing manufacturing steps in the method of the present invention.

FIG. 17 is a schematic cross-sectional view of a mold showing manufacturing steps in the method of the present invention.

FIG. 18 is a schematic cross-sectional view of a mold showing manufacturing steps in the method of the present invention.

FIG. 19 is a schematic sectional view of a mold showing manufacturing steps in the method of the present invention.

[Explanation of symbols]

 1: Skin layer 2: Expansion layer 6: Female type 7: Male type 8: Resin supply device 9: Resin supply path 10: Resin supply port 11: Vacuum suction port 12: Thermoplastic resin 14: Slide core 15: Hydraulic cylinder 16 : Skin material 17: opening hole opening / closing valve 18: opening hole 19: atmosphere path 20: pin-like object 22: sliding surface 23: skin layer non-formed portion 24: projection or groove 25: skin layer 26: foam layer 27: resin Layer 28: hollow

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // B29K 101: 12 B29K 101: 12 105: 04 105: 04 B29L 31:00 B29L 31:00 F term ( Reference) 4F202 AB02 AB25 AG20 CA09 CA11 CB01 CB13 CK19 CP06 CQ01 CQ05 4F204 AB02 AB25 AG20 FA01 FB01 FB13 FN11 FN12 FQ15 4F206 AB02 AB25 AG20 AG28 JA04 JB13 JF04 JM05 JN26 JN33 JN35 JQ81

Claims (7)

[Claims] 1. A mold comprising a pair of male and female having at least one vacuum suction port opened on a molding surface of one or both of the male and female molds so as to continuously surround the periphery of at least one vacuum suction port. A mold for manufacturing a lightweight molded article of a thermoplastic resin, characterized in that a projection or a groove is provided on a molding surface. 2. The mold for producing a lightweight molded article of thermoplastic resin according to claim 1, wherein the projections or grooves are provided along the outer periphery of the molded article or along the vicinity thereof. 3. The mold for producing a lightweight molded article of a thermoplastic resin according to claim 1, wherein a communicating portion for communicating the inside of the mold cavity with the atmosphere is provided between the molds. 4. A step of using the mold according to claim 1, 2 or 3, wherein (a) supplying a molten thermoplastic resin between the molds and filling the thermoplastic resin into the mold cavity. , (B)
A step of opening a part or all of the mold in the thickness direction of the molded body while sucking the vacuum from the mold molding surface; A method for producing a lightweight molded article of a thermoplastic resin, comprising: 5. The thermoplastic resin according to claim 4, wherein the starting thermoplastic resin contains a foaming agent, and the foaming agent is contained in an amount of 0.01 to 5% by weight based on the thermoplastic resin. Manufacturing method of lightweight molded body. 6. The process for producing a lightweight thermoplastic resin article according to claim 4, wherein the raw material thermoplastic resin contains reinforcing fibers having an average fiber length of 3 mm or more. 7. A skin material is supplied in advance between both molds, and a thermoplastic resin is supplied between the skin material and one of the mold molding surfaces. A method for producing a lightweight molded article of a thermoplastic resin as described above.