JPH05245947A - Method for press molding expandable lamination sheet - Google Patents

Abstract

PURPOSE:To conduct uniform foaming and press molding of an expandable thermoplastic lamination sheet which has a skin material sheet on one or either side and a sandwiched foaming resin inside. CONSTITUTION:An expandable lamination sheet 1 which has a skin material sheet on one or either side and a sandwiched resin inside is hold by pressing the periphery of its pressing surface with a pressing member 5 of a press- molding machine. In this state, the sheet is heated and simultaneously pressured by charging a hot compressed gas from a gas passage 7 to prevent foaming. When the skin material sheet 3 of the expandable thermoplastic lamination sheet 1 is heated to the temperature which is enough high to permit the molding of the sheet and the foaming of the expandable resin, the compressed gas is discharged at once, and press molding is performed simultaneously with a projected mold 4. The molded product is expanded uniformly and has strong mechanical strength.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for foam molding and press molding an unfoamed expandable laminated sheet.

[0002]

2. Description of the Related Art Conventionally, Japanese Patent Laid-Open No. 1-95032 discloses a technique for molding a foamable laminated sheet with a mold. In this publication, heating is performed in a state in which an unfoamed foamable polyolefin sheet and a synthetic resin sheet are bonded together to foam the foamable polyolefin sheet and soften the synthetic resin sheet, and immediately thereafter, vacuum forming is performed. And press molding at the same time, and the press molding is disclosed to deep-draw a laminated plate of a foamed polyolefin sheet and a synthetic resin sheet with a press molding machine having a female mold and a male mold. .. 4 and 5 are cross-sectional views of the molding process diagram of the conventional press molding machine disclosed in the above publication. In these drawings, a laminated sheet having a skin material sheet 23 and two kinds of foam layers 21 and 22 is provided in a space between a female mold 26 and a male mold 24 of a press molding machine, and the skin material sheet 23 is a female plate. The step of arranging so as to face the mold 26 side and performing vacuum molding at the same time as press molding with the male mold 24 is shown.

[0003]

When press-molding a foamable laminated sheet with a press die, in order to make foaming as uniform as possible, the foamable laminated sheet is set in a press molding machine, and the sheet is set. It is necessary to heat both sides of the sheet to a uniform temperature while restraining both sides, and it is important not to cause foaming during the heating.

However, in the press molding of the foamable thermoplastic resin sheet having the above-mentioned conventional skin material sheet, the sheet is first heated before being set in the press molding machine to be already foamed and immediately pressed. Molded by a molding machine. Therefore, since the sheet is already formed on the foam layer, the foam layer is crushed,
A uniform foam layer was not formed in the entire molded product.

Therefore, the present invention provides a method for uniformly foaming and press-molding a foamable laminated sheet having a skin material sheet on one side or both sides and sandwiching a foaming resin inside.

[0006]

In order to solve the above problems, the present invention provides a foamable laminated sheet having a skin material sheet on at least one surface, and has a male mold and a female mold.
Using a press molding machine having a pressing member slidably arranged around the male mold and capable of restraining both surfaces of the foamable laminated sheet by pressing the foamable laminated sheet against the edge of the female mold, The foamable laminated sheet is constrained by sandwiching the foamable laminated sheet between the female mold of the molding machine and the pressing member, and the male mold and the female mold of the press molding machine are heated and the constrained at the same time. In the space between the foamable laminated sheet and the female mold, a pressurized gas is supplied to apply pressure, and in the pressurized state, the foamable laminated sheet is uniformly heated to form the skin material sheet. Continue heating until it reaches a temperature that is possible, release pressurized gas to release the pressurized state, and cause foaming at once, and at the same time press-mold a foamable laminated sheet characterized by press molding with a male mold. It is an act.

Further, the present invention provides a molding method in which an airtight sheet is sandwiched between the foamable laminate and the female mold for press molding in order to maintain the airtightness of the pressurizing space during pressurization. Is. In addition, the pressurized gas is a heating gas,
The heating can be efficiently performed simultaneously with the pressurization. Also,
Pressurization can be performed more effectively by leaking the pressurized gas and then vacuuming.

The foamable laminated sheet referred to in the present invention means a sheet having a skin material sheet on one side or both sides of a foamable thermoplastic resin sheet having a property of causing foaming when heated in an unfoamed state. .. The foamable thermoplastic resin sheet may be any sheet that causes foaming by heating. For example, a thermoplastic resin sheet impregnated with methylene chloride or the like as a foaming agent is preferably used. The resin used in this thermoplastic resin sheet is not limited to the following, but for example, polyetherimide, polyethersulfone, polycarbonate, polymethylmethacrylate are preferably used.

To impregnate this thermoplastic resin sheet with methylene chloride, for example, methylene chloride, which is a foaming agent, is put in the bottom of the container and the thermoplastic resin sheet is placed in the upper part.
It is obtained by impregnating the thermoplastic resin sheet with methylene chloride by evaporating methylene chloride. Another method for producing the expandable thermoplastic resin sheet is as follows. A thermoplastic resin dissolved in methylene chloride is sandwiched between two thermoplastic resin sheets, or one thermoplastic resin sheet is used. There is a method of manufacturing by applying to a sheet.

The foaming agent used in the production of the expandable thermoplastic resin sheet is not limited to methylene chloride.
A chemical foaming agent which is liquid or solid at room temperature and has a property of thermally decomposing upon heating to generate a gas can be used. Examples of such foaming materials include azodicarbonamide, barium azodicarboxylate, N, N'-dinitrosopentamethylenetetramine, 4,4-oxybis (benzenesulfonylhydrazide), diphenylsulfone-3,3-disulfonyl. Examples thereof include hydrazide, p-toluenesulfonyl semicarbazide, trihydrazinotriazine, biurea and zinc carbonate. In order to manufacture a foamable thermoplastic resin sheet using such a foaming agent, it can be manufactured by mixing a chemical foaming agent into a thermoplastic resin and extruding.

The foamable laminated sheet referred to in the present invention is obtained by providing a skin material sheet on at least one surface of these foamable thermoplastic resin sheets. A fiber reinforced thermoplastic resin sheet is preferably used in consideration of durability and the like in the skin material sheet, and the fiber reinforced thermoplastic resin sheet includes, for example, a woven fabric or a non-woven fabric such as glass fiber, carbon fiber, or aramid fiber. A sheet in which the thermoplastic resin is impregnated is preferably used. As the thermoplastic resin to be impregnated, it is advantageous in terms of adhesiveness to use the same resin as the thermoplastic resin used when manufacturing the foamable thermoplastic resin sheet.

A method of joining the skin material sheet to the foamable thermoplastic resin sheet is performed by hot pressing with a hot press. Usually to prevent foaming
After the hot pressing, the sheet is taken out after cooling under pressure. A press molding machine having a male mold and a female mold used in the present invention is formed around the male mold so as to be slidable with respect to the male mold, and has a pressing member for pressing both sides of the expandable thermoplastic resin sheet. The female mold has a gas passage for introducing a pressurized gas and releasing the pressurized condition.

[0013]

In the present invention, the reason why press molding is performed in a heated / pressurized state is as follows. When the foamable laminated sheet is press-molded without being pressed, foaming is caused by heating in the state of being set in the press molding machine, so in the space between the female mold and the foamable laminated sheet, This is because there is a problem that the foam on the female side of the expandable thermoplastic resin sheet is likely to expand before pressing, and the expandable thermoplastic resin sheet is not uniformly expanded.
That is, such non-uniform foaming, that is, if there is local foaming, large pores are generated in the foamed layer in some places, and mechanical properties such as strength and elastic modulus deteriorate in that portion, Also, there is a disadvantage that large pores are generated between the skin material sheet and the foam, and the strength of the interface between them is weakened, or the surface of the foamed molded article becomes uneven.

In the present invention, when the foamable laminated sheet is heated, the female side of the foamable laminated sheet is pressed by hydrostatic pressure to suppress foaming, and the foamable laminated sheet is entirely heated. After that, the pressurization state is released all at once, so that the foam molding is uniformly performed in the mold and the press molding is performed at the same time.

[0015]

Example 1 FIG. 1 is a cross-sectional view showing a state before forming an expandable laminated sheet with a press molding machine used in Example 1 of the present invention, and FIG. 2 is an example of the present invention. FIG. 2 is a cross-sectional view showing a state in which the expandable laminated sheet is molded into a thermoplastic resin foam by the press molding machine used in No. 1.

Reference numeral 4 denotes a male mold of a press molding machine, and the male mold 4
A cylindrical pressing member 5 is slidably in contact with the male mold 4 around the periphery of the male mold 4 concentrically with the male mold 4. Reference numeral 6 denotes a female die arranged so as to face the male die 4, and the foamable laminated sheet 1 is formed by the die-matching surface of the female die 6 formed so as to face the holding member 5 and the holding surface of the holding member 5. It can be clamped. Further, the female die 6 has a gas passage 7 for supplying and leaking pressurized gas.

Reference numeral 1 denotes a foamable laminated sheet used in the present invention, and the foamable laminated sheet 1 comprises a foamable thermoplastic resin sheet 2 and a skin material sheet 3 provided on both sides thereof. Next, a method for molding the expandable laminated sheet 1 using the above press molding machine will be described. Unfoamed foamable laminated sheet 1
Is clamped and fixed by the female die 6 and the pressing member 5 of the press molding machine. The foamable laminated sheet 1 is heated by heating the female mold 6, the male mold 4 and the pressing member 5. At this time, since the foamable laminated sheet 1 starts foaming, a hydrostatic pressure is applied to the foamable laminated sheet 1 by supplying the heated and further pressurized gas from the gas passage 7 of the female mold 6. The pressure prevents the foamable laminated sheet 1 from partially foaming. The foamable laminated sheet 1 reaches the foaming temperature uniformly and is heated uniformly, and the heating is continued until the skin material sheet 3 reaches a softened state so as to be moldable. In this state,
As shown in, the pressurized gas is leaked from the gas passage 7,
At the same time when foaming is caused at once, press molding is performed by the male mold 4.

[0018]

Example 2 This Example 2 is another example of the method for press-molding the expandable laminated sheet 1, and FIG. 3 shows the press-molded state. In the second embodiment, in the press molding by the press molding machine of the first embodiment, in order to further maintain the airtightness of the space inside the female mold 6 and enhance the pressurizing effect, the foamable laminated sheet 1 and the female mold 6 are combined. An airtight sheet 8 was sandwiched between them, and press molding was performed in this state in the same manner as in Example 1.

[0019]

As described above in detail, according to the present invention, in press molding using a foamable laminated sheet having a skin material sheet on one side or both sides and sandwiching a foaming resin inside, It is possible to obtain a press-formed product in which uniform foaming has been performed. Further, since the molded product has uniform foaming, a mechanical product having a uniform mechanical strength and no voids between the skin material and the foam layer can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state before a foamable laminated sheet is molded by a press molding machine used in Example 1.

2 is a cross-sectional view showing a state where a foamable laminated sheet is molded into a thermoplastic resin foam by the press molding machine used in Example 1. FIG.

FIG. 3 is a cross-sectional view showing press molding of Example 2.

FIG. 4 shows a cross section of a molding process diagram of a conventional press molding machine.

FIG. 5 shows a cross section of a molding process diagram of a conventional press molding machine.

[Explanation of symbols]

 1 Foamable laminated sheet 2 Foamable thermoplastic resin sheet 3 Skin material sheet 4 Male type 5 Holding member 6 Female type 7 Gas passage 8 Airtight sheet

Claims (4)

[Claims] 1. A foamable laminated sheet having a skin material sheet on at least one surface is prepared, and (2) a male mold and a female mold are provided, which are slidably disposed around the male mold. Using a press molding machine having a pressing member capable of restraining both sides of the foamable laminated sheet by pressing the foamable laminated sheet on the edge of the female mold, (3) the female mold of the press molding machine and the pressing member And restraining the foamable laminated sheet by sandwiching the foamable laminated sheet with (4) heating the male mold and the female mold of the press molding machine, and simultaneously restraining the foamable laminated sheet and the female mold. A pressurized gas is supplied to the space to pressurize, and (5) the foamable laminated sheet is uniformly heated in the pressurized state, and the skin material sheet on the surface of the foamable laminated sheet Continue heating until it reaches a moldable temperature , (6) a pressurized gas once to cause a foam by releasing the pressurized state by leaks, is press-molded by the male mold at the same time, foaming press-forming method of the laminated sheet characterized by. 2. The foaming property according to claim 1, wherein an airtight sheet is sandwiched between the foaming laminate and the female mold in order to maintain the airtightness of the pressurizing space during the pressurization. Press forming method for laminated sheet. 3. The method of press molding a foamable laminated sheet according to claim 1, wherein the pressurized gas is a heating gas. 4. A press-molding method for a foamable laminated sheet, which is characterized in that following the steps (1) to (6) of claim 1, the pressurized gas is leaked and then vacuumed.