JPH0631802A - Composite sheet for drawing - Google Patents

Abstract

PURPOSE:To make uniform the wall thickness of a product made of a composite sheet for drawing. CONSTITUTION:A composite sheet is a three-layered laminate which is composed of a thermoplastic resin sheet 1, a foamed crosslinked thermoplastic resin sheet 2, and a thermosetting resin adhesive layer 3 sandwiched between the two resin sheets. On both sides of a three-layered molding part S1 in the middle of the composite sheet S is formed a two-layered clamp part S2 not including the adhesive layer 3. The thermoplastic resin sheet 1 consists of a soft upper layer 11 and a hard lower layer 12. When the molding part S1 of the composite sheet S is pressed in a mold while the clamp part S2 being clamped, the clamp part S2 is easily stretched so that the molding part S1 can fit the mold and its local stretching is prevented to make the wall thickness of the product uniform. Moreover, by contacting the soft upper layer 11 of the thermoplastic sheet 1 on an embossed pattern of the mold, the pattern is correctly transcribed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a draw-forming composite sheet used for draw-forming the surface layer of an automobile instrument panel, for example.

[0002]

2. Description of the Related Art As such a draw forming composite sheet, the one shown in FIG. 6 has been generally used. The molding composite sheet S has a structure in which a thermoplastic resin sheet 1 and a thermoplastic crosslinked foamed sheet 2 are laminated in three layers with a thermosetting resin adhesive 3 interposed therebetween. .

By the way, when performing draw forming using the molding composite sheet S, the peripheral edge of the molding composite sheet S is clamped and pushed down toward the lower mold to lower the upper mold, thereby lowering the lower mold and the upper mold. And the composite sheet S for molding is sandwiched between and. At this time, the central molding portion of the molding composite sheet S whose peripheral edge portion is clamped is clamped and stretched by the lower mold and the upper mold, but the conventional molding composite sheet S is a thermosetting resin adhesive. Due to the presence of 3, the tensile strength becomes excessively large, which makes it difficult for the mold to fit evenly, and depending on the shape of the mold, a large amount of local expansion occurs and the wall thickness becomes uneven, and cracks and the like occur from the thin wall portion. Damage could occur.

Therefore, a clamp made of one layer of the thermoplastic resin sheet 1 is provided around the periphery of the molding composite sheet S made of three layers of the thermoplastic resin sheet 1, the thermoplastic crosslinked foamed sheet 2 and the thermosetting resin adhesive 3. And a clamp portion having a low tensile strength is stretched at the time of molding to form a composite sheet S for molding.
It has been proposed to make the central part of the mold evenly fit in the mold (see Japanese Utility Model Publication No. 62-13789).

[0005]

However, since the thermoplastic resin sheet 1 of the molding composite sheet S described in the above publication has a small tensile strength particularly at the time of high temperature molding, it easily breaks at the clamp portion, and deep drawing is performed. There is a problem that it is difficult to use for goods. Further, the surface of the conventional molding composite sheet S is difficult to adapt to the fine irregularities of the molding die, and it is difficult to accurately transfer the irregular pattern such as the skin pattern of cowhide.

The present invention has been made in view of the above-mentioned circumstances. The molded product molded from the molding composite sheet has a uniform thickness to prevent a thin portion from being generated, and a fine uneven pattern of the molding die. The purpose is to be able to transfer accurately.

[0007]

To achieve the above object, the present invention provides a composite sheet obtained by laminating a thermoplastic resin sheet and a thermoplastic crosslinked foamed sheet with a thermosetting resin adhesive interposed therebetween. In, a clamp part composed of two layers of a thermoplastic resin sheet and a thermoplastic crosslinked foamed sheet is formed at the periphery of a molded part composed of three layers of a thermoplastic resin sheet, a thermoplastic crosslinked foamed sheet and a thermosetting resin adhesive. In addition, the first feature is that the thermoplastic resin sheet is composed of two layers, an upper layer and a lower layer, and the upper layer is formed softer than the lower layer.

In addition to the above-mentioned first feature, the present invention also provides:
A second feature is that the clamp portion is composed of a lower layer of the thermoplastic resin sheet and a thermoplastic crosslinked foamed sheet.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a draw forming die D of a forming composite sheet S is for forming a surface layer portion of an automobile instrument panel, and includes a fixed lower die D _L and this lower die D. An upper mold D _U that can move up and down with respect to _L is provided.

The lower die D _L comprises a bottom plate 11, a lower die body 12 provided on the bottom plate 11, and a box body 13 for covering the outer periphery of the lower die body 12. A large number of vent holes 12 ₁ are formed on the surface of the lower mold body 12, and the internal space 12 ₂ thereof is connected to the vacuum pump 14. The core material C, which is placed on the upper surface of the lower mold body 12 and is made of ABS resin or the like, has a large number of ventilation holes C ₁ communicating with the ventilation holes 12 ₁ of the lower mold body 12.

The upper mold D _U includes a top plate 15, an upper mold body 16 provided under the bottom plate 15, a pattern shell 17 provided on the lower surface of the upper mold body 16, and an upper mold body 16. And a box 18 that covers the outer circumference. An uneven pattern is formed on the surface of the pattern shell 17 to form a cowhide skin pattern on the surface of the molding composite sheet S. The upper mold body 16 and the pattern shell 17 have a porous structure having fine continuous pores through which air can pass. The internal space 16 ₁ of the upper mold body 16 is selectively connected to the vacuum pump 20 or the blower 21 via the switching valve 19.

Between the lower mold D _L and the upper mold D _U of the molding die D, a plurality of clamp claws 22 for holding a clamp portion, which will be described later, formed on the peripheral edge of the molding composite sheet S are provided so as to be vertically movable. To be

As shown in FIG. 3, the molding composite sheet S of this embodiment is a comparatively thin thermoplastic resin sheet 1 made of polyvinyl chloride, polyolefin resin or the like, which serves as a skin layer.
(Thickness: 0.9 mm), a relatively thick thermoplastic crosslinked foamed sheet 2 (thickness: 3.0 mm) such as polypropylene, polyethylene, or polyolefin that serves as a cushion layer, the thermoplastic resin sheet 1, and the thermoplastic resin sheet. It has a three-layer structure in which a thermosetting resin adhesive 3 such as a two-pack type polyester resin interposed between the crosslinked foamed sheets 2 is laminated. The thermoplastic resin sheet 1 comprises a lower layer 1 ₂ of two layers of an upper layer 1 ₁ and the thickness 0.45mm thickness 0.45mm, top layer 1 ₁ hardness is a shore A50, the lower 1 ₂ Hardness Shore A5
It is formed to be softer than 8. Thermoplastic resin sheet 1
The decrease in the hardness of polyvinyl chloride, which is a material of the above, is achieved by decreasing the degree of polymerization thereof or by increasing the amount of the plasticizer added.

The thermoplastic resin sheet 1 and the thermoplastic crosslinked foamed sheet 2 have the same dimensions of 1000 mm in width and 2200 mm in length, and the thermosetting resin adhesive 3 sandwiched therebetween has a width of 800 mm and a length of 2 mm. Is 2200 mm.
Therefore, the center portion of the molded composite sheet S is formed molded portion S ₁ of the three-layer structure, a molded portion S ₁ of the longitudinal side edge clamp portion S ₁ of thermosetting resin adhesive 3 is not interposed
Is formed into a strip having a width of 100 mm.

Next, the operation of the embodiment of the present invention having the above construction will be described.

As shown in FIG. 1, the lower mold D of the mold D_Las well as
Upper mold D_UWith the mold open, lower mold D_LOn top of the core material C
On the surface of the core material C, and apply hot melt adhesive to it.
Cloth is softened by heating. Then heat to about 180 ° C to soften
The formed composite sheet S is clamped at its clamp portion S.₂Ku
Lower mold D gripped by the lamp claw 22_LAnd upper mold D_UWith
Placed between the upper mold D_UAnd the clamp claw 22 to the lower mold D_LTo
Lower toward you. As a result, the molding die D is shown in FIG.
And the molding composite sheet S is lower mold D. _LAnd above
Type D_UIt is pinched and stretched between the two and comes into contact with the surface of the core material C.
Be worn. At this time, the switching valve 19 is moved to the vacuum pump 20 side.
Switching, fine pattern formed on the pattern shell 17 and the upper mold body 16
Internal space 16 formed in continuous pores and upper mold body 16₁
Composite sheet for molding by sucking air through
The upper surface of S is the upper mold D_UStrongly adheres to the pattern shell 17 of
Is transcribed. At this time, heat that contacts the pattern shell 17
Surface layer 1 of plastic resin sheet 1₁Is the lower layer 1₂Softer than
Because it is made, the upper layer 1₁Easily on the pattern shell 17
The uneven pattern is transferred accurately.

When the draw forming is completed in this way, the vacuum pump 14 is operated to adsorb and hold the core material C and the lower surface of the molding composite sheet S protruding from the core material C on the lower mold body 12 and switching the same. The core 19 and the molding composite sheet S are opened by switching the valve 19 to the blower 21 side and opening the molding die D while ejecting air from the pattern shell 17 of the upper mold D _U onto the upper surface of the molding composite sheet S. The molded product in which and are integrated is separated from the upper mold D _U and remains in the lower mold D _L. The molded product separated from the molding die D is completed by cutting off the molding composite sheet S protruding from the core material C. Clamping part S ₂ cut from the molding part S ₁ of the molding composite sheet S
Is composed mainly of the thermoplastic resin sheet 1 and the thermoplastic crosslinked foamed sheet 2, and contains almost no thermosetting resin adhesive 3, so that the thermoplastic resin sheet 1 and the thermoplastic crosslinked foamed sheet 2 can be easily formed. It can be peeled off and separated. As a result, the clamp portion S ₂ cut out from the molding composite sheet S can be sorted by material and easily reused as a synthetic resin material.

Now, in the above-mentioned draw forming process,
The molding composite sheet S gripped by the pump claw 22 is the lower mold D._L
And upper mold D_UThermosetting when sandwiched and stretched
Molding part S of molding composite sheet S having resin adhesive 3₁
Is difficult to stretch due to its high tensile strength, but the clamp claw 22
Therefore, the clamp portion S of the molding composite sheet S to be gripped ₂
Is a thermoplastic resin sheet 1 and a thermoplastic crosslinked foamed sheet 2
Composed of only no thermosetting resin adhesive 3
Therefore, this clamp S₂By stretching the
Forming part S of composite sheet S₁Fully adapts to mold D
be able to. As a result, the forming part of the forming composite sheet S
S₁Unevenness in the wall thickness due to local elongation
To avoid molding, and obtain a molded product with uniform and sufficient wall thickness.
be able to. Moreover, the clamp part S₂Is relatively thick
Since the thermoplastic crosslinked foamed sheet 2 is included, this clamp portion
S₂Does not have the disadvantage of being excessively stretched and broken.

[0020]

[Table 1] Table 1 shows that the thermoplastic resin of the molding composite sheet S from the pattern shell 17 when drawn by using the conventional molding composite sheet S of FIG. 6 and the molding composite sheet S of this embodiment of FIG. 3 respectively. This is for comparing the depths of the uneven pattern (grain pattern) transferred on the sheet 1. Here, the grain depth formed on the pattern shell 17 side of the upper mold D _U is 129 μm,
The depth of the grain transferred from the pattern shell 17 to the thermoplastic resin sheet 1 side was measured with a universal surface roughness meter.

As is clear from this table, the conventional one having a surface hardness of Shore A68 of the thermoplastic resin sheet 1 has a grain depth of 113 μ and a transfer rate of 88%, whereas the surface hardness is more than that. The shore A50 having a low shore A50 also has a grain depth of 124 μ and a transfer rate of 96%, and it is understood that the transfer performance of the grain pattern is significantly improved.

FIG. 4 shows a second embodiment of the present invention.
The molding composite sheet S has the same dimensions as the upper layer 1 ₁ is a thermosetting resin adhesive 3 of the thermoplastic resin sheet 1. Therefore, the clamp portion S ₁ is composed of two layers of the lower layer 1 ₂ of the thermoplastic resin sheet 1 and the thermoplastic crosslinked foam sheet 2. Also in this embodiment, the clamp portion S is formed at the time of drawing.
_It is possible to appropriately reduce the tensile strength of No. ₂ to prevent the stretched portion S ₂ from being locally stretched, and to make the thickness uniform.

FIG. 5 is a graph showing the relationship between "elongation" and "tensile strength" of the composite sheet S for molding. As is clear from the figure, a three-layer structure of the thermoplastic resin sheet 1, the thermoplastic crosslinked foamed sheet 2 and the thermosetting resin adhesive 3 shown in FIG. S
(Corresponding to ₂ ) has the highest tensile strength, and has a two-layer structure of the thermoplastic resin sheet 1 (upper layer 1 ₁ and lower layer 1 ₂ ) and the thermoplastic crosslinked foamed sheet 2 shown in (B) (for molding in the first embodiment). corresponding to the clamp portion S ₂ of the composite sheet S) is to tensile strength decreases, (thermoplastic resin sheet 1 shown by C) (lower 1 ₂ only) and a two-layer structure of the thermoplastic crosslinked foamed sheet 2 (the Clamping part S of the molding composite sheet S of the second embodiment
(Corresponding to ₂ ) has further reduced tensile strength. It is understood that (D) has a one-layer structure of the thermoplastic resin sheet 1 (described in the above-mentioned publication), and because its tensile strength is extremely low, it easily breaks in the drawing forming example.

Thus, by appropriately reducing the tensile strength of the clamp portion S ₂ of the forming composite sheet S as compared with that of the forming portion S ₁ , the clamp portion S ₂ is positively stretched and formed during drawing. It is possible to prevent local stretching of the portion S ₁ , thereby making the thickness of the molded portion S ₁ uniform, and moreover, the upper layer 1 ₁ of the thermoplastic resin sheet ₁ and the lower layer 1 ₂
By making it softer than that, the transfer performance of the uneven pattern can be improved.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various design changes can be made.

For example, the present invention can be applied not only to the instrument panel but also to molding of any member such as a door trim.

[0027]

As described above, according to the first feature of the present invention, the thermoplastic resin sheet, the thermoplastic crosslinked foamed sheet, and the thermosetting resin adhesive are formed on the periphery of the molding portion of the thermoplastic resin sheet. Since the clamp part consisting of two layers of the resin sheet and the thermoplastic crosslinked foamed sheet is formed, the clamp part can be made to fit into the mold without being locally stretched by locally stretching the clamp part during molding. it can. As a result, the thickness of the composite sheet for molding after molding is made uniform, and its strength and durability are improved. Moreover, since the upper layer of the thermoplastic resin sheet is formed softer than the lower layer, the uneven pattern can be accurately transferred to the upper layer. Furthermore, since the clamp part cut off from the composite sheet for molding after the completion of molding contains almost no thermosetting resin adhesive, the thermoplastic resin sheet and the thermoplastic crosslinked foamed sheet can be easily separated and reused as a synthetic resin material. Can be used.

According to the second aspect of the present invention, by excluding the upper layer of the thermoplastic resin sheet from the clamp portion, the tensile strength of the clamp portion is further weakened so that the molding portion can be more easily adapted to the molding die. be able to.

[Brief description of drawings]

FIG. 1 is a sectional view showing a state where a molding die is opened.

FIG. 2 is a cross-sectional view showing a state where the molding die is clamped.

FIG. 3 is a sectional view of a molding composite sheet according to the first embodiment.

FIG. 4 is a sectional view of a molding composite sheet according to a second embodiment.

FIG. 5 is a graph showing the relationship between elongation and tensile strength of a molding composite sheet.

FIG. 6 is a sectional view of a conventional molding composite sheet.

[Explanation of symbols]

1 Thermoplastic Resin Sheet 1 ₁ Upper Layer 1 ₂ Lower Layer ₂ Thermoplastic Crosslinked Foam Sheet 3 Thermosetting Resin Adhesive D Mold D S ₁ Molding Part S ₂ Clamping Part

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location B32B 5/18 101 // B29K 105: 04 B29L 31:58 4F

Claims (2)

[Claims] 1. A draw-forming composite sheet obtained by laminating a thermoplastic resin sheet (1) and a thermoplastic crosslinked foamed sheet (2) with a thermosetting resin adhesive (3) sandwiched therebetween. The thermoplastic resin sheet (1) and the thermoplastic crosslink are provided on the periphery of the molding part (S ₁ ) composed of three layers of the resin sheet (1), the thermoplastic crosslink foam sheet (2) and the thermosetting resin adhesive (3). A clamp part (S ₂ ) consisting of two layers of a foamed sheet (2) is formed, and the thermoplastic resin sheet (1) is composed of two layers of an upper layer (1 ₁ ) and a lower layer (1 ₂ ). A draw-forming composite sheet, wherein 1 ₁ ) is formed softer than the lower layer (1 ₂ ). 2. The clamp part (S ₂ ) is composed of a lower layer (1 ₂ ) of the thermoplastic resin sheet (1) and a thermoplastic crosslinked foamed sheet (2). Composite sheet for drawing.