JPH04212851A - Molding method of synthetic resin sheet and molded form thereof - Google Patents

Abstract

PURPOSE:To transfer an irregular pattern positively even when a complicate shape such as an undercut section is formed while effectively preventing the generation of creases, sag, etc. CONSTITUTION:A synthetic resin sheet 60 is formed integrally of a skin layer 62 mainly comprising a thermoplastic synthetic resin, a holding layer 64 mainly comprising the same thermoplastic synthetic resin as said skin layer 62 and a synthetic resin foamed layer 66 generating the heat of decomposition by a heating temperature at the time of the molding and containing a secondarily foamed foaming agent. The synthetic resin foamed layer 66 of the synthetic resin sheet 60 molding-regulated by a pattern mold 34 and a force 20 is secondarily foamed by a molding heating temperature, the skin layer 62 is contact-bonded with the whole irregular pattern 40 of the pattern mold 34 by the blowing pressure, and the irregular pattern 40 is transferred to the skin layer 62.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a synthetic resin sheet having a thermoplastic synthetic resin skin layer and a synthetic resin foam layer capable of secondary foaming, and to a molded product thereof.

0002

2. Description of the Related Art For example, interior bodies incorporating automobile instrument panels, console boxes, etc. are often provided with a delicate uneven pattern (grain pattern) similar to natural leather to give a sense of luxury and softness.

Various proposals have been made in the past to provide this type of uneven pattern. For example, the technical idea is disclosed in Japanese Patent Laid-Open No. 104848/1983, for which the present applicant has already filed a patent application. Disclosed.

[0004] This prior art involves polymerizing a synthetic resin sheet heated to a high temperature on a pattern molded by electroforming to have a cowhide-like uneven pattern and providing fine continuous pores. The synthetic resin sheet is vacuum-sucked into a pattern shape, thereby transferring the uneven pattern onto the surface of the synthetic resin sheet.

[0005]

[Problems to be Solved by the Invention] Incidentally, interior bodies such as instrument panels, etc. have become noticeably larger and more complex in shape than before, and the above-mentioned conventional technology has made it possible to reduce the size of deep-drawn parts, especially It is difficult to reliably transfer an uneven pattern to a portion having an undercut portion.

[0006] Furthermore, since synthetic resin sheets are molded and embossed in a heated and softened state, the shrinkage rate increases due to stretching and the like during molding, and this is particularly noticeable in large sheets. For this reason, it is difficult to maintain the precision of alignment between the skin layer and the cushion layer or core material that constitute the synthetic resin sheet, and there is a problem in that wrinkles, sagging, etc. occur on the surface.

The present invention solves this kind of problem, and is capable of reliably transferring an uneven pattern even when having a complex shape, for example, an undercut part.
It is an object of the present invention to provide a method for molding a synthetic resin sheet and a molded product thereof, which makes it possible to effectively prevent the occurrence of wrinkles, sagging, etc.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a skin layer made of a thermoplastic synthetic resin;
A process of obtaining a synthetic resin sheet having a synthetic resin foam layer containing a foaming agent for secondary foaming, a first mold having fine communication holes and an uneven pattern on the surface, and The method further comprises a step of transferring the uneven pattern to the skin layer by applying a foaming pressure to cause secondary foaming of the foaming agent at a molding heating temperature with respect to the synthetic resin sheet held between an opposing second mold. shall be.

Furthermore, the present invention provides a skin layer made of a thermoplastic synthetic resin, on which a concavo-convex pattern is transferred, and a skin layer made of a thermoplastic synthetic resin, which is laminated on the skin layer and prevents drawdown at molding temperatures. and a synthetic resin foam layer laminated on the retention layer and having a primary foam layer and a secondary foam layer that are foamed at different times depending on the heating temperature.

0010

[Function] In the method for molding a synthetic resin sheet and the molded product thereof according to the present invention, the foaming agent in the synthetic resin sheet sandwiched between the first mold and the second mold is heated to a temperature of 1. When the next foaming is performed, this synthetic resin sheet itself has a space regulated by the first mold and the second mold,
That is, it expands within the cavity. Therefore, the skin layer of the synthetic resin sheet can be reliably polymerized on the part of the first mold where the uneven pattern is provided, and the transfer work of this uneven pattern can be carried out efficiently and with high precision. become.

Furthermore, secondary foaming of the foaming agent makes it possible to effectively reduce the shrinkage rate of the synthetic resin sheet.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for molding a synthetic resin sheet and a molded article thereof according to the present invention will be described in detail below with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 indicates a molding device, and this molding device 10 includes a lower movable section 12 and an upper movable section 14.

The lower movable part 12 has a frame 16, and a press mold (second mold) 20 is provided in the upper opening 18 of the frame 16.
is placed. A core material (described later) is placed on the top surface of the pressing mold 20.
A recess 22 for fitting is formed, and a plurality of vacuum suction holes 24 are formed so as to be uniformly distributed through the pressing die 20. This vacuum suction hole 24 communicates with a vacuum pump 28 from inside the frame 16 via a tube 26 .

The upper movable part 14 has a frame 30, and a pattern mold (first mold) 34 made of an electroforming mold having a desired molded object shape is disposed in a lower opening 32 of the frame 30. be done. This pattern 34 is attached to the lower end of the frame 30 and a plurality of angle members 36 fixed to the frame 30 by bolts 38.
It is attached via.

The pattern 34 is made of nickel electroformed body,
A cowhide-like uneven pattern 40 is formed on the surface facing the pressing die 20 side. A large number of fine communication holes 42 are formed in the pattern 34 so as to be uniformly distributed over the entire thickness thereof, and the fine communication holes 42 are used as vacuum suction holes and air supply holes.

Inside the frame 30, there is a first backup layer 44 having continuous pores located between the back side of the pattern 34 and the angle material 36, and a second backup layer 44 having continuous pores located above the angle material 36. A backup layer 46 is arranged. The first backup layer 44 is formed by partially bonding a large number of steel balls with excellent corrosion resistance, such as stainless steel, with a thermosetting synthetic resin such as an epoxy resin, and the second backup layer 46 is composed of a large number of glass balls, which are made of a thermosetting synthetic resin such as an epoxy resin. The beads are partially joined together using the same thermosetting synthetic resin as described above.

The first backup layer 44 has a pattern 34
A cooling pipe 48 is buried in a meandering manner to uniformly cool the entire body.

The fine communication holes 42 of the pattern 34 are connected to the first backup layer 44, the second backup layer 46 and the tube body 5.
0 to a switching valve 52, and a vacuum pump 54 and a blower 56 are connected to this switching valve 52.

Therefore, in this embodiment, a synthetic resin sheet 60 is first obtained. As shown in FIG. 2, this synthetic resin sheet 60 includes a skin layer 62 mainly made of a thermoplastic synthetic resin such as vinyl chloride resin, and a skin layer 62 mainly made of a thermoplastic synthetic resin similar to the skin layer 62 during molding. Retaining layer 64 for appropriately retaining drawdown (sagging, etc.) depending on the heating temperature
and a synthetic resin foam layer 66 containing a foaming agent that generates decomposition heat and secondary foams due to the heating temperature during molding.

The holding layer 64 is made of a thermoplastic material such as acrylic resin, or a thermoplastic woven or nonwoven fabric.

The synthetic resin foam layer 66 is mainly made of thermoplastic synthetic resin such as vinyl chloride resin, and the foaming agent used is azodicarbonan amide, azobisisobutyronitrile, or other polyolefin resin. Also, as the foaming aid, there is used one that causes primary foaming at about 150°C and secondary foaming at the molding temperature (about 190°C). This synthetic resin foam layer 66 has been heated to undergo primary foaming.

On the other hand, the core material 70 has a plurality of small-diameter vacuum suction holes 72 in a plate made of ABS resin or the like, and is molded to correspond to the recesses 22 of the pressing die 20 (see FIG. 1). .

Next, in order to mold the synthetic resin sheet 60 into a desired shape, the lower movable part 12 is lowered and the upper movable part 14 is raised to form the press mold 20 and the pattern mold 3.
4 are separated from each other. The core material 7 is placed in the recess 22 of this pressing die 20.
0 is arranged, and the vacuum suction holes 72 and 24 communicate with each other. Further, the synthetic resin sheet 60 is heated to a temperature of 180°C to 200°C.
When the skin layer 62 is placed between the press die 20 and the pattern die 34 with the skin layer 62 facing toward the pattern die 34, the press die 20 is raised and the pattern die 3 is heated.
4 are lowered, and the synthetic resin sheet 60 is held between them (see FIG. 3). At this time, the fine communication holes 42 of the pattern 34 are communicated with the vacuum pump 54 via the switching valve 52, and under the action of the vacuum pump 54, the synthetic resin sheet 6
0 is vacuum-suctioned into this pattern 34.

In this case, in this embodiment, the synthetic resin foam layer 66 of the synthetic resin sheet 60 is heated at a molding heating temperature (approximately 190° C.
) contains a foaming agent that generates decomposition heat and causes secondary foaming, and this synthetic resin sheet 60 is heated to 180°C to 200°C.
is heated to. For this reason, the pattern mold 34 and the pressing mold 20
The synthetic resin foam layer 66 of the synthetic resin sheet 60, whose molding is regulated by the 40 is transferred. Particularly, even when the pattern 34 is large and has an undercut, the uneven pattern 40 of the undercut can be reliably and clearly transferred to the skin layer 62 through the foaming pressure. can get. At this time, since the synthetic resin sheet 60 is vacuum-suctioned to the pattern mold 34 under the action of the vacuum pump 54, the transfer operation of the uneven pattern 40 to the skin layer 62 can be performed more accurately.

Furthermore, the temperature of the synthetic resin sheet 60 can be prevented from decreasing due to the effect of the decomposition heat generated when the synthetic resin foam layer 66 undergoes secondary foaming and the heat insulating properties of the foam itself. transfer conditions can be effectively maintained.

Further, since the synthetic resin foam layer 66 undergoes secondary foaming, the stretching of the synthetic resin sheet 60 during molding becomes small, and as a result, the molding shrinkage rate can be reduced. As a result, the synthetic resin sheet 6 after molding
It is possible to prevent wrinkles, bends, etc. from occurring on the surface of the 0, making it possible to obtain a highly accurate molded product.

After the molding operation is completed, the vacuum pump 28 on the lower movable part 12 side is driven, and the synthetic resin sheet 60 is pumped through the vacuum suction hole 24 of the pressing mold 20 and the vacuum suction hole 72 of the core material 70. Vacuum suction is applied to the pressing die 20 and the core material 70, and the blower 56 communicates with the tube body 50 via the switching valve 52, and blower pressure is applied to the synthetic resin sheet 60 from the fine communication holes 42 of the pattern die 34. . As a result, the synthetic resin sheet 60 after molding is released from the pattern die 34 and is integrally joined to the core material 70 in close contact with it to obtain a molded body. This molded body is taken out from the press die 20 after the lower movable part 12 and the upper movable part 14 are separated from each other.

Next, another example of the method for molding a synthetic resin sheet and its molded product according to the present invention will be described below with reference to FIG. Note that the same reference numerals as in the molding apparatus 10 shown in FIG. 1 indicate the same components, and detailed explanation thereof will be omitted.

In this case, the lower movable part 102 constituting the molding device 100 has a backup layer 108 provided between the frame 104 and the pressing die 106, and the backup layer 108
is constructed by partially bonding a large number of glass beads to each other with a thermosetting synthetic resin, and has continuous pores 110. This continuous pore 110 is connected to a blower 114 through a pipe body 112.
communicate with.

In this configuration, the synthetic resin sheet 60 is heated to 180° C. to 200° C., as in the molding device 10, and then held between the pressing mold 106 and the pattern mold 34, and the vacuum pump 54 is Under the action, a synthetic resin sheet 60 is vacuum-suctioned onto this pattern 34. At this time, in this embodiment, compressed air is led out from the pipe body 112 to the synthetic resin sheet 60 through the continuous pores 110 under the driving action of the blower 114, and the pressing force of this compressed air causes the skin layer 62 to
However, the effect is that the entire uneven pattern 40 of the pattern mold 34 is pressed more reliably with a uniform force. Next, a blower 56 is communicated with the pipe body 50 via the switching valve 52, and blower pressure is applied to the synthetic resin sheet 60 to obtain a molded article.

Note that in this embodiment, the synthetic resin sheet 60
is constructed by laminating a skin layer 62, a retaining layer 64, and a synthetic resin foam layer 66, but for example, the retaining layer 64 and the synthetic resin foam layer 66 may be replaced, or the retaining layer 6
4 and the synthetic resin foam layer 66 may be configured as a single layer.

[0033]

[Effects of the Invention] According to the method for molding a synthetic resin sheet and the molded product thereof according to the present invention, the following effects can be obtained.

[0034] The synthetic resin sheet is first
By applying vacuum to the mold side and secondary foaming of the foaming agent at the molding heating temperature, it is possible to reliably polymerize the skin layer of the synthetic resin sheet in the portion of the first mold where the uneven pattern is provided. can. Therefore, even if the molded product is relatively large and has an undercut, the uneven pattern of the undercut can be clearly transferred, and the transfer work can be carried out efficiently and with high precision. be able to.

Furthermore, secondary foaming of the foaming agent effectively reduces the shrinkage rate of the synthetic resin sheet, making it possible to obtain a molded article with high precision.

[Brief explanation of the drawing]

FIG. 1 is a front vertical cross-sectional view of a molding apparatus for carrying out the synthetic resin sheet molding method according to the present invention.

FIG. 2 is an enlarged explanatory view of a synthetic resin sheet.

FIG. 3 is an explanatory diagram of the operation of the molding device.

FIG. 4 is a front vertical cross-sectional view of a molding apparatus for carrying out a synthetic resin sheet molding method according to another embodiment of the present invention.

[Explanation of symbols]

10, 100...molding device 12, 102...lower movable part 14...Upper movable part 20, 106...press type 34...Pattern type 40...Uneven pattern 42...Minute communication hole 60...Synthetic resin sheet 62... Epidermal layer 64...Retention layer 66...Synthetic resin foam layer 70...core material

Claims (4)

[Claims] Claim 1: A process for obtaining a synthetic resin sheet comprising a skin layer made of a thermoplastic synthetic resin, a synthetic resin foam layer containing a foaming agent for secondary foaming, and a process for obtaining a synthetic resin sheet having fine communication holes and irregularities on the surface. The said synthetic resin sheet, which is held between a first molding mold provided with a pattern and a second molding mold facing the first molding mold, is formed with the unevenness due to the foaming pressure that causes the foaming agent to undergo secondary foaming due to the molding heating temperature. A method for molding a synthetic resin sheet, comprising the step of transferring a pattern to the skin layer. 2. The method of forming a synthetic resin sheet according to claim 1, wherein vacuum suction is applied to the synthetic resin sheet through fine communication holes, and the uneven pattern is formed in the skin layer by the vacuum suction force and foaming pressure. A method for molding a synthetic resin sheet, which is characterized by transferring the image onto a sheet. 3. The method for molding a synthetic resin sheet according to claim 1, wherein compressed air is supplied to the synthetic resin sheet from a second mold, and the unevenness is formed by the pressing force and foaming pressure of the compressed air. A method for molding a synthetic resin sheet, the method comprising transferring a pattern to the skin layer. 4. A skin layer made of a thermoplastic synthetic resin and having a concavo-convex pattern transferred thereon; and a draw layer made of a thermoplastic synthetic resin and laminated on the skin layer to prevent drawdown at molding heating temperatures. a retention layer as a down prevention layer;
A molded article of a synthetic resin sheet, comprising a synthetic resin foam layer laminated on the holding layer and having a primary foam layer and a secondary foam layer that are foamed at different times depending on the heating temperature.