JPS58183226A - Method and apparatus for obtaining molding body having different density from each other - Google Patents

Abstract

PURPOSE:To improve the efficiency of molding of foamed resin products, having an improved strength, by performing molding while organically combining a heating die and a cooling die of transfer die molding devices. CONSTITUTION:A feeder 6 is operated, and a die indentation 5 is supplied and filled with preparatorily foamed thermoplastic resin grains. Mantle sections 8, 9 are supplied with a heating medium from supply ports 10, 11 to heat the inside of the die indentation 5. Resin grains are plasticized while being further foamed, mutually welded by inner pressure and integrated, and changed into a semimanufactured good. When the supply of the heating medium is stopped and a male die 2 is backed, the semimanufactured good is separated from a female die 4, and held by the male die 2. The male die 2 is moved, connected to a female die 18, and cooled by cold water supplied to a mantle section 23 from a supply port 25. Supply and discharge ports 10, 12 for the male die 2 are supplied with compressed air while backing the male die 2 as sucking the die 2 by vacuum from supply and discharge ports 24, 27, a waiting male die 16 is connected to the cooling female die 18, a semimanufactured good A' is compressed by the male die 16, and a section A having large density is formed.

Description

[Detailed description of the invention] Further foam molding is performed in a hot mold to form a semi-finished product, and the semi-finished product is transferred to a cooling mold and compression molded to form a product, 1% rn.
i. This invention relates to a transfer molding method, and in particular to a transfer molding method and apparatus for producing a product in which the density of resin constituting a molded body is partially changed as necessary.

In this document, "density" refers to "apparent density" unless otherwise specified.

In general, foamed resin molded products have excellent heat retention properties. Buffering effect 1
It has a wide range of uses as a packaging material for various articles due to its characteristics such as toughness f1'', chemical stability, light weight and low cost.

Such a molded body is usually made of a thermoplastic resin that is uniformly foamed throughout and has an equal density distribution of 1W, but it is difficult to remove the parts that are subject to special impact or pressure, such as corners or tightened parts. Some methods have been used in the past in which parts that require a large degree of strength, such as parts where I# fixing fittings are attached, are formed to have increased density. For example, there is a method in which separate molded bodies are made using different types of foamed resin H materials that give different strong IWs, and they are integrated by means such as adhesion, or a method in which a part of the mold cavity for molding is completely closed is used. After filling the foamable resin material and performing the first foam molding, the closed part is opened and the created cavity is filled with a different type of foamable resin material. A 17-day device was developed to perform the
No. 38) etc. are being proposed by 1.

The conventionally proposed or practiced method is to perform separate molding using multiple molding molds. In some cases, it may be necessary to combine and bond the molded bodies, or it may be necessary to fill the foamed resin with a mold having complicated special grooves and perform two molding steps multiple times. Because of the complicated culm operations such as these, production efficiency is low and equipment investment is increased, which are disadvantageous.

Originally, in foam molding of thermoplastic resin, the entire process cycle of heating, remolding, and cooling JDL was used for the same molding.
Since the molding process is carried out within 47 mm, there is a problem in that the heat energy is consumed and the time required for the culm cycle is large, which is a factor that reduces the productivity of the above-mentioned special molding method. This is the result.

Such heat 1 plastic f1, during the time inherent in resin foam molding
To solve this problem, the invention disclosed in Japanese Patent Application Laid-Open No. 52-905'78 provides an excellent method.

This invention is a so-called transfer molding method, in which thermoplastic f1 resin particles J'-
Particles are completely filled and heated to plasticize and expand.
After the semi-finished product is taken out of the heating mold and foaming is completed, the molded product is molded into a molded product with a shape of 4JS and 4JS, which more accurately corresponds to the molded product to be manufactured.
By inserting the semi-finished product into a cooling mold having a cooling method, a final product with stable hardening is obtained. In this method, an IJn heating mold and a cooling mold are used, which have mold cavities of a shape and size very similar to those of the IJn mold, and the half mold is removed from the heating mold and heated on June 1st. The product also has only a slightly higher density in the epidermis, which is substantially similar to the mold cavity and is referred to as a layer.

In view of the current state of the technology and the problems mentioned above, the inventors of the invention have improved and developed the invention of JP-A No. 52-90578, and the density of the resin constituting the entire molded article can be adjusted to iVli as necessary. Efficiently process partially changed products
1; Nitorii! This invention is aimed at J'! ! ”
't'+': 1 no 7 Again.

In other words, the method of climbing the tree θ, i that achieves the purpose mentioned above
i, a mold cavity for molding is formed with a male mold and a female mold of −λ1, respectively, using a heating mold and a cooling mold,
The thermoplastic resin particles that have been exfoliated are filled into the mold cavity of the above + JII heat mold and fused to the PP-foamed cementing phase r7 to form an integral semi-finished product, and then the semi-finished product is cooled. In the transfer molding method, the product is compressed and molded while being cooled.
The thickness of the part of the semi-finished product corresponding to t is the product design-1111
) The semi-finished product is molded so that it is appropriately larger than the thickness, and then compression molded using a cooling mold until the thicker part reaches the designed thickness.

The feature of the apparatus of the present invention for carrying out such a method is that it consists of two sets of molding molds capable of forming a mold cavity with a pair of mutually openable and female molds, respectively.
The first mold is equipped with an inlet for supplying expandable thermoplastic resin particles into the mold cavity and a means for heating the inside of the mold cavity, and the second mold is equipped with a means for releasing the molded object in the mold cavity. and 2. cooling means. In a transfer type molding apparatus configured so that the MF mold of one mold can be connected and disconnected from the female mold of the other mold, the high density of the molded body molded in the second mold is required. The reason is that the NI' method in the depth direction of the mold cavity of the first mold corresponding to the part to be made is appropriately larger than the dimension of the corresponding part of the second mold.

Hereinafter, embodiments of the present invention will be explained in detail with reference to the accompanying drawings. Figures 1, 7F and 2 are longitudinal cross-sectional views of a molding die applied to the method of the present invention, and Figure 1 shows a heating mold or , FIG. 2 shows a cooling type.

In FIG. 1, a male mold (2) attached to a mold frame (1) and a female mold (4) attached to a mold frame (3) close each other to form a mold cavity (5). The female mold (4) is usually fixed to a frame (not shown), and the opening and closing of the mold is controlled by the male mold (2).
), but the reverse is of course possible.

For example, in the example shown in Fig. 1, a feeder (6) for foamed thermoplastic resin particles (f-f+iif) with a molding raw material is placed in the female mold (4) with its feed port (7) connected to the mold cavity. (5)
It can be installed close to the inside. Male type (2) and female type (4)
On the back of each is a mantle (8) partitioned by a formwork (1) and a formwork (3).

(9) is formed, and a heating medium such as 7711 hot steam is supplied to the mantle (R1, (91) from the heating medium supply ports OO) and (), respectively, and heats the mold cavity (5) circle through the mold. Then, it is discharged from the discharge port (121, (1: Inflow.

Historically, the molded body was released from the mold by supplying compressed air from these heating medium supply ports (101, αD and exhaust ports (121, You can

Here, an example is shown in which the heating fluid is used as the heating medium as the heating means of the mold 7JIl, but it can be easily replaced with other commonly used means by a simple design change.

The molding die shown in FIG. 2 is combined with the mold shown in FIG. 1 to constitute the apparatus of the present invention. In Fig. 2, the male die 06) attached to the formwork (15) and the female die 08) attached to the formwork (17) are closed to each other in the same manner as described above.
form 9. Again, the female mold 0 is usually fixed to the frame (not shown) -F, and the opening and closing of the mold is controlled by the male mold (l l
i), but the reverse is also possible.

In addition, the male mold (2) is connected to the female mold (4) and (18) by an appropriate mechanism so that the female mold 08) can be connected to and detached from the male mold (2) in Fig. 1.
) is one husband so that he can go back and forth.

Needless to say, if the male type is a fixed type, the female type will be a mobile type. Furthermore, one of the molds in Fig. 2, for example, the female mold 08, is fitted with a Sanno-dam ejector (2 (
11 is the attachment via gasket i.

Further, a cooling mantle (221c23) is formed on the back of each of the male molds (Hil and female mold 08). The refrigerant supply to the refrigerant such as air or cold water enters the mantle a) from the refrigerant supply r-11241) and is discharged from the refrigerant outlet (21i1-).Of course, in addition to forced cooling with refrigerant, just place it in the air. In some cases, natural cooling is preferable.

Note that a direct air device (not shown) for suctioning and holding the product is connected to the refrigerant supply [ ] or the refrigerant discharge port.

The two sets of molding molds shown in FIGS. 1 and 2, each consisting of a pair of male and female molds, are combined to constitute the transfer molding apparatus of the present invention. The most distinctive features are the shape of each mold cavity and the design of the q1 method. In other words, the shape of the mold cavity in the cooling mold shown in Figure 2.
The dimensions generally correspond strictly to the shape and dimensions of the designed product, but the shape and dimensions of the mold cavity in the heating mold shown in Fig. 1 are as follows.
In the part (A) corresponding to the part (A) of the final product that requires particularly high density, the thickness is suitably larger than the specified thickness of the product.

Here, thickness refers to the dimension in the depth direction of the mold cavity, that is, the dimension along the axis in the opening/closing direction of the mold.

Next, the mode of carrying out the method of the present invention using such an apparatus will be described in detail along with its operation.

[- In the above-mentioned apparatus, first, the supply device (6) is operated with the heating mold closed, and the thermoplastic resin particles, such as polystyrene beads, are pre-foamed into the mold cavity (5) from the supply port (7). Supply and fill with polyethylene beads, etc. However, polystyrene beads are particularly preferably used in the present invention.

Although the preliminary expansion ratio of these raw resins can be up to about 100 times, it is usually preferable to use a ratio of about 30 to 60 times.

After filling the raw materials, a heating medium, most preferably made of heated steam, is supplied to the mantle (8) from the heating medium supply port (101, 01).
.

(9) and internal f! of mold cavity (5). r: 110-1
If heated to about 20°C, the resin particles will plasticize and further foam in less than 10 seconds, and will fuse together due to internal pressure [7]
They are integrated into a semi-finished product.

Stop the supply of heating medium when the time is right for integration.F
When the male mold (2) is moved back and the mold is opened, the semi-finished product is separated from the female mold (4) and is supported on the male mold (2). In order to ensure release from the female mold, a release agent such as silicone is applied to the inner surface of the mold in advance, or back pressure is applied using compressed air from the outer part (9) of the female mold.
Or, conversely, it is preferable to generate zero pressure by placing the mold behind the male die.

The male mold (2) carrying the semi-finished product then moves to a position where it confronts the female mold θR of the defensive type shown in Figure 2, and then moves forward and unites with the female mold 0. , the semi-finished product is moved into a free atmosphere during this transfer. A flow path is formed in the rear mantle color of the female type 0, through which cold water is supplied from the refrigerant supply port 1 to the most preferable tL<, and is discharged from the refrigerant discharge port. The semi-finished product inserted into the female mold (18) by the advance is cooled starting from the portion that contacts the cooled inner wall surface of the female mold (18).

Note that the purpose of cooling is often achieved only with air blown for mold release, and in this case, it is not necessary to discharge from the discharge port.

Next, compressed air is supplied from the heating medium supply port OI and the discharge port α2 of the male mold (2) to apply back pressure, and while vacuum suction is applied from the refrigerant supply port (2'' or the refrigerant discharge port), the male mold (
If 2) is moved back, the semi-finished product will remain inside the female mold 0&,
At the same time as the male die (2) comes off the central axis of the female die 0&,
The cooling male mold 06), which was waiting at a distance, moves forward and the cooling female mold 0
8).

The male type (lli) is cooled by a refrigerant such as cold water flowing from the refrigerant supply port to the refrigerant discharge port (2).

The thickness of the part <i> of the shape of the product, that is, the dimension θ in the depth direction, is larger than the thickness of the corresponding part of the mold cavity of the cooling mold. As it moves forward, it is compressed more than other parts, and by shrinking to the product design thickness, a denser part FA) is formed.

The density of the high-density portion (A) depends on the relationship between the phantom thickness and the thickness of (N) and the pre-expansion rate of the thermoplastic resin, but if the pre-expansion rate is 40 to 60 times ( thickness)/(
A thickness of about Density can be obtained. In addition, in order to provide a substantial difference in strength from other parts, it is desirable that the thickness ratio be 9 or more, more preferably 1 or more.

Depending on the part of the product where such a high-density part is to be formed, its purpose, and the state of use of the product, the heating mold cavity corresponding to that part is arbitrarily selected. The thickness may be appropriately designed to be large.

3 and 5 both show the longitudinal cross-sectional shape of a heating mold cavity, and FIGS. 4 and 6 respectively show the corresponding cooling mold cavity, that is, the vertical cross-sectional shape of the product.

Part cA) in Figure 3 is thicker, so that part is especially compression molded, and the high-density part tA) shown in Figure 4 is
is formed. Fig. 5 shows a molded article in which the high-density part (A)' shown in Fig. 6 is formed from the part (A) corresponding to the corner, and the corner has a high impact strength. This is an example of acquiring.

In this way, the molded product made of cotton in the cooling mold is approximately 10 to 2
It hardens and stabilizes by cooling the row for 0 seconds, then M1 type (16
) to open the mold, open the refrigerant supply port or refrigerant discharge [
The molded body is released from the mold by completely stopping the vacuum device sucking from 1 and simultaneously ejecting the ejector C (υ).

As is already clear from the above explanation, the present invention skillfully utilizes and improves the transfer molding method, so it can be heated and foamed in the same mold as conventional foam molding. - cooling process cycle f! :It is possible to perform molding operations one after another in a short cycle by organically combining the constantly heated IJII hot mold and the constantly cooled cooling mold without spending a long time. Losses can also be reduced and, if necessary,
The density of the molded product can be increased appropriately in any part of the molded product, and therefore, the foamed resin product with increased strength can be produced easily and conveniently by simply changing the shape of the mold cavity of the heating mold.
This invention is extremely useful in the field of foam molding technology because it uses II resin and can be obtained at low cost and with high efficiency without requiring any particularly complicated equipment.

Examples of the method of the present invention will be described below.

(Example) Using the transfer molding apparatus shown in FIGS. 1 and 2, polystyrene beads having a particle size of 2 to 5 mm and an average pre-foaming ratio of about 50 times were foam-molded. The mold cavity shape of cooling j%lJ is top outer diameter 300m, inner diameter 180m, center thickness 50mm, edge thickness 60cm, lower edge outer diameter 310rM.
I, the shape of the mold cavity of the heating type is the same as that of the cooling type, except that it has a conical shape with an inner diameter of 190 mm, and a protruding part 6') with a diameter of 6 degrees and a thickness of 25 mm in the central part. Dimensions. ff
1J, the thickness of the central part is 75 mm, and the thickness of the surrounding area is 1.5 mm.
It was double that.

The heating mold was closed, the raw material feeder was activated, and the pre-expanded polystyrene beads were loaded into the mold cavity. Foam molding was carried out for 8 seconds at a humidity of 120°C.After stopping the supply of water vapor, the steam supply rl (I
l+ and the exhaust port (13 (inject more compressed air and push the molded body together with the male steam supply port QO) and the exhaust port (
From 12), the male mold (2) was moved back while suctioning ξ' 1. The resin molded body sucked and supported by the male mold (2) costs $
I7f is highly fused and integrated into a semi-finished product.

The male mold (2) was then moved to a position facing the female mold 0 mark of the cooling mold, and the molded body was inserted into the female mold 081. In that state, the mantle (8) behind the male mold (2)
) was supplied with compressed air, and with the back pressure, the molded object was pushed all the way forward together with the refrigerant supply port (25).

The molded body left in the female mold 08) is then engaged in forward engagement (1
The mold was closed using a J1 male mold (16). The molded product is hardened by cooling for about 10 to 20 seconds,
The morphology was stable. The mold was opened and the parishioner device connected to the refrigerant supply port (251) was stopped, and the ejector (2(1)) was protruded to release the molded product from the mold.

The density IW of the central part of the obtained molded body is 0.02B~0°0
It had an excellent breaking strength of 30 V, which was about twice that of the other parts, which had a 0.02 V.

[Brief explanation of drawings]

Figures 1 and 2 show heating 1% lJ of the device of the present invention, respectively.
FIG. 3 is a vertical sectional view showing an embodiment of the cooling type. 3111 and 5 are longitudinal sections ['
Figures 1, 4, and 6 are longitudinal cross-sectional views of a mold cavity of a cooling mold corresponding to Z1 of the IJn thermal mold of Figs. 3 and 5, respectively, or a vertical cross-sectional view of a product. (21 (lfil ME type, (4) Want... female type. f!'51 (191... type fossa, (7)...
Resin particle supply [1゜(IO+ (11+...Heat medium supply port, (20+...Ejector. ・(24105+...Refrigerant supply rl, A, A'
... Parts that require high density. Patent source Kanekabuchi Chemical Industry Co., Ltd. I+, □□ Light □1F-Q・74- - 〆【゛＼Pole 3 1 Rod 3 eye A'A' Hana 4 Shi I Imo ni eye

Claims (1)

[Claims] l A heating mold and a cooling mold each having a pair of male and female molds each capable of forming mold cavities are used, and the pre-foamed thermoplastic resin particles are placed in the mold cavities of the heating molds. In the transfer molding method, the semi-finished product is filled with heat, foamed, and fused together to form an integral semi-finished product.The semi-finished product is then transferred to a cooling mold and compressed while cooling to form a product. The semi-finished product is molded so that the thickness of the part of the semi-finished product corresponding to the area that requires high density is appropriately larger than the design thickness of the product 7, and then the thicker part is molded using a cooling mold. A method for molding a molded article having different densities, which is characterized by compression molding until it reaches a designed thickness. The major part of the thickness is approximately 11O~4 of the product's designed thickness.
A method for molding a molded article having different densities according to claim 1, wherein the semi-finished product is molded to have a thickness of 0.00%. 3 The major part of the thickness is approximately 120 to 2 of the designed thickness of the product.
A method for molding a molded body having different densities according to claim 2, wherein the semi-finished product is molded so as to have a thickness of 0.00%. It consists of two sets of molding molds each having a pair of male and female molds that can be freely opened and closed to form mold cavities, and the first mold is used to inject expandable thermoplastic resin particles into the mold cavities. supply []
and a means for heating the inside of the mold cavity, the second mold is equipped with a means for releasing the molded object in the mold cavity and a means for cooling it, and further, the male mold of one mold is heated in the mold cavity of the other mold. In a transfer type molding device configured to be able to engage and disengage from the female mold of the mold, the first mold corresponding to the "T" part that requires high density of the molded product to be molded in the second mold is used. An apparatus for molding a molded article having different densities, characterized in that the dimension υ in the depth direction of the mold cavity of the mold is set to be appropriately larger than the dimension of the corresponding part of the second mold. The molding having different densities according to claim 4, wherein the dimension in the depth direction of the mold cavity of the first mold is about 110 to 400% of the dimension of the 7.1 corresponding part of the second mold. Body molding device. The heterogeneous body molding device according to claim 5, wherein the dimension in the depth direction of the mold cavity of the first mold is about 120 to 200% of the dimension of the corresponding part of the second mold. A molding device for molded bodies with density.