JP2001179818A - Vacuum forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum forming method which can mold a sheet 12 to be molded accurately by making the sheet sufficiently follow the surface shape of a molding mold 13 without breaking the sheet 12 even for the mold 13 having a complex three-dimensional shape on its surface. SOLUTION: After the sheet 12 extended above the mold 13 is heated/ softened, a space on its upper side is pressurized, a space on the lower side is evacuated, and the sheet 12 is pressed on the surface of the mold 13 by the pressure difference. After that, a flexible sheet 11 extended above the sheet 12 is pressed to the sheet 12 pressed on the surface of the mold 13 by using the pressure difference between the two surfaces so that the sheet 12 is further pressed on the surface of the mold 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum forming method for forming a thermoformable sheet into a two-dimensional or three-dimensional three-dimensional shape.

[0002]

2. Description of the Related Art A vacuum forming method as a method for forming a two-dimensional or three-dimensional complex three-dimensional shape from a thermoforming sheet such as a plastic film is conventionally known. In the manufacture of containers such as home appliances, housings for home appliances, electrical and mechanical parts such as refrigerator interior parts, stationery and toys, and various other three-dimensional sheet molded products,
Widely used.

[0003] In addition, at the same time as forming a molded sheet into a three-dimensional shape by a vacuum forming method, a decorative sheet as a molded sheet is laminated and adhered to the surface of a decorative substrate as a molding die, or as a molded sheet. A method of applying a surface treatment such as painting by transfer to the surface of a base material to be decorated by molding and adhering the transfer sheet to the surface of the base material to be decorated as a molding die is also well known in the art. Manufacture of interior materials for vehicles such as instrument panels and door interior materials, construction materials such as interior doors for kitchens, kitchen doors, storage doors, etc., furniture materials, and equipment housings, etc. Is widely used.

[0004] The above-mentioned vacuum forming method is to spread a thermoforming sheet on the surface of a molding die, and heat and soften the molding sheet in a space on the molding die side of the molding sheet. And pressurizing the space on the opposite side of the molding die of the molded sheet, and pressing the molded sheet against the surface of the molding die by utilizing the pressure difference between the two spaces, thereby forming the molded sheet. This is a method of forming a shape along the surface of a molding die.

[0005] At the time of the molding, the molded sheet itself may be used as a medium for applying a pressing force based on the pressure difference between the spaces on both sides of the molded sheet. However, in this case, if the thickness of the molded sheet or the strength of the material is insufficient. As a result, when the mold is pressed into contact with the mold, stress concentrates on a portion pressed into contact with a protrusion, a corner, or the like of the mold, and as a result, the sheet to be molded is broken at the portion and is formed as initially intended. May not be possible.

On the other hand, there is no fear of the above-mentioned molding defects, and the selection range of various molding conditions such as the thickness and material of the sheet to be molded, the three-dimensional shape of the surface of the molding die, molding pressure and molding speed, etc. As a wider vacuum forming method, a flexible sheet such as a silicone rubber sheet is disposed on the side opposite to the forming die of the sheet to be formed, and the flexible sheet is used as a pressure impressing medium to form the sheet to be formed into a forming die. The so-called membrane press forming method of pressing against the surface of a material is well known in the art, and is widely used for various purposes.

However, in the conventional membrane press forming method, the flexible sheet and the sheet to be formed are simultaneously pressed against the surface of the forming die in a state of being overlapped. It is virtually the same as pressing the sheet body having the surface of the three-dimensional shape of the molding die, so for a more complicated three-dimensional shape, particularly for a molding die having acute corners and deep recesses, etc. However, the sheet to be molded cannot be formed by sufficiently following the three-dimensional shape of the surface thereof, and it has been difficult to stably produce a molded article having high shape accuracy.

[0008] The above problem is caused by using a decorative sheet or a transfer sheet as a sheet to be molded, using a substrate to be decorated as a molding die, and pressing and laminating them on the surface of the substrate to be decorated. Or, in the case of transfer, it is particularly serious because it becomes a serious defect that cannot be overlooked in appearance or performance, such as swelling, poor adhesion, poor transfer, and the like.

[0009]

SUMMARY OF THE INVENTION The present invention has been made for the purpose of solving the above-mentioned problems in the prior art, and is also applicable to a molding die having a complicated three-dimensional shape on the surface. It is another object of the present invention to provide a vacuum forming method capable of forming a sheet to be formed with high precision by sufficiently following the surface shape of a forming die without causing a breakage of the sheet to be formed.

[0010]

According to the present invention, there is provided a mold for forming a sheet to be formed, which is obtained by spreading a thermoformable sheet on the surface of the mold and heating and softening the sheet. By depressurizing the space on the side and pressurizing the space on the opposite side of the molding die of the sheet to be molded, and pressing the molded sheet against the surface of the molding die by utilizing the pressure difference between the two spaces, In the vacuum forming method of forming a molded sheet into a shape along the surface of the molding die, after pressing the sheet to be molded against the surface of the molding die according to the above procedure, the opposite side of the molding sheet of the molded sheet is placed on the opposite side to the molding die. The expanded flexible sheet is depressurized in the space on the molding die side of the flexible sheet and pressurized in the space on the side opposite to the molding die of the flexible sheet, utilizing the pressure difference between the two spaces. And the flexible sheet is pressed against the surface of the molding die pressed against the surface of the molding die. The mold by pressure contact with the surface opposite a vacuum forming method characterized by further pressed against the surface of the mold for molding to be molded sheet.

In particular, the present invention relates to a vacuum forming apparatus which can be divided into three chambers, an upper chamber, a lower chamber, and a lower chamber. The sheet to be molded on the surface, the molds are arranged on a molding die mounting table installed in the lower chamber, respectively, and in a state where the molded sheet is heated and softened, the pressure in the lower chamber is reduced, The inner chamber is pressurized, and the sheet to be formed is pressed against the surface of the mold using the internal pressure difference between the lower and upper chambers. Thereafter, the inner chamber is depressurized and the upper chamber is pressurized. By utilizing the internal pressure difference between the middle chambers, the flexible sheet is pressed against the surface of the molding sheet pressed against the surface of the molding die, on the surface opposite to the molding die, thereby forming the molding sheet. Is further pressed against the surface of a molding die.

In particular, in the present invention, in the step of heating and softening the sheet to be molded, the upper chamber and the inner chamber are depressurized and the lower chamber is maintained at a higher pressure than the upper and middle chambers, so that the sheet is flexible. The sheet to be formed is brought into contact with the heating means provided on the ceiling of the upper chamber through the flexible sheet, and the heat of the heating means is transmitted to the sheet to be formed through the flexible sheet, thereby forming the sheet to be formed. This is a vacuum forming method characterized by being performed by heating.

[0013] In particular, in the present invention, the step of heating and softening the sheet to be molded preferably comprises maintaining the lower and middle chambers at substantially the same pressure and maintaining the sheet to be molded substantially horizontally, and In the lower chamber, after the heating means capable of moving back and forth between the forward position above the forming die and the retracted position retracted therefrom is advanced to the forward position, and after the sheet to be molded is heated and softened, , Retract the heating means to the retracted position,
A vacuum forming method characterized by performing a subsequent step.

[0014] In particular, the present invention provides a method for forming a flexible sheet on the surface of a molding die by depressurizing the inner chamber and pressurizing the upper chamber to utilize the internal pressure difference between the upper and lower chambers. The step of pressure-contacting the surface of the sheet to be molded pressed against the surface opposite to the molding die is a vacuum forming method characterized in that the lower chamber is held in a reduced pressure state.

More particularly, the present invention provides the flexible sheet, wherein the flexible sheet has a thickness of 0.5 to 5 mm, an elongation of at least 530% in a temperature range of 20 ° C. to 30 ° C., and a tensile strength of 75,000.
１５０150,000 Pa (about 75 to 150 kgf / cm ² )
A vacuum forming method characterized in that the sheet is a heat-resistant elastomer sheet.

[0016] More particularly, the present invention provides a method wherein the molding die is a decorative substrate, the molded sheet is a thermoformable decorative sheet, and the decorative sheet is pressed against the surface of the decorative substrate. Thus, the decorative sheet is formed into a shape along the surface of the base material, and the decorative sheet is laminated and adhered on the surface of the base material.

[0017] More particularly, the present invention relates to a transfer sheet, wherein the molding die is a base material to be decorated, and the molded sheet has a transfer layer provided releasably on one surface of a thermoformable support sheet. By pressing the surface of the transfer sheet on the transfer layer side against the surface of the base material to be coated, the transfer sheet is formed into a shape along the surface of the base material to be coated, and the transfer layer of the transfer sheet is coated with the base material. This is a vacuum forming method characterized by transferring onto a surface of a substrate.

[0018]

According to the vacuum forming method of the present invention, the first step is to press the sheet to be formed on the surface of the molding die itself as a pressure impressing medium, and thus to preform the sheet on the surface of the molding die. A second step of further adhering a flexible sheet to the formed sheet under vacuum, and further pressing the formed sheet against the surface of the molding die using the flexible sheet as a pressure impressing medium;
Since it is performed in two stages, in the first stage, molding is performed under mild conditions to avoid breakage of the molded sheet, and even if the followability to the surface shape of the molding die is insufficient, the second stage In the above, the portion where the sheet to be molded does not sufficiently adhere to the surface of the molding die can be brought into close contact with the pressing force of the flexible sheet.

In addition, since the sheet to be molded and the flexible sheet are individually pressed against the surface of the molding die at each stage, they are compared with the conventional method in which both are pressed against the surface of the molding die at the same time. As a result, the degree of freedom in deformation at the time of molding is increased, and the sheet to be molded can be molded by sufficiently following the surface of the molding die having a more complicated three-dimensional shape.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the vacuum forming method of the present invention will be described below in detail with reference to the drawings. FIG.
FIG. 3 is an explanatory view showing an embodiment of a vacuum forming method of the present invention in the order of steps.

In the embodiment shown in FIG. 1, the upper chamber 1, the middle chamber 2 and the lower chamber 3 can be divided into three chambers. A vacuum forming apparatus provided with a depressurizing means such as a pressurizing means and a vacuum pump, a depressurizing means such as a vacuum pump in the lower chamber, and a heating means 16 such as a hot plate on the ceiling of the upper chamber 1. You are using

First, the molding die mounting table 15 in the lower chamber 3
A molding die 13 whose surface is processed into a desired three-dimensional shape to be molded with the molded sheet 12 is arranged. On the bottom surface of the molding die mounting table 15, a large number of suction holes connected to a pressure reducing means such as a vacuum pump for discharging air inside the lower chamber 3 and reducing the pressure are formed at predetermined intervals. It is common.

The material of the molding die 13 is not particularly limited, but is, for example, wooden, metal, synthetic resin, or the like. In the case where the molding die 13 is a decorative base material for laminating a decorative sheet or applying a transfer picture by a transfer sheet, for example, a wooden base material such as a medium density fiberboard or a particle board, a steel material or an aluminum molding material Metallic base materials such as bodies, inorganic base materials such as calcium silicate plate and lightweight cellular concrete, synthetic resin base materials such as ABS resin and FRP, or composites and laminates thereof, have been used for cosmetic materials. Any material used as a substrate can be used. An adhesive may be previously applied to the surface of the base material to be coated as necessary.

The adhesive may be a solvent type, a thermosetting type,
Any adhesive such as a moisture curing type, an ionizing radiation curing type, a pressure sensitive type, and a heat sensitive type can be used. It is desirable to use a curable adhesive in terms of the durability of the cosmetic material to be manufactured, but from the viewpoint of molding workability, it exhibits adhesiveness by heat during molding, and quickly solidifies by cooling after molding. The heat-sensitive adhesive (hot melt adhesive) is easier to use. Therefore, when a reactive hot melt adhesive having both properties is used, it is excellent in molding workability, and after molding, it can be irreversibly cured by a chemical reaction to obtain a cosmetic material having excellent durability. There are advantages.

The molding die 13 may be simply placed directly on the molding die mounting table 15. However, the molding sheet 12 is formed into a shape extending to a part of the side surface or the back surface of the molding die 13. In this case, the molding die 13 is generally mounted on the molding die mounting table 15 via a molding jig 15 having a slightly smaller area than the back surface of the molding die 13. . In addition, in order to assist in forming the sheet 12 along the three-dimensional shape of the surface of the molding die 13, an appropriate shape of the appropriate shape is placed at an appropriate position on the molding die mounting table 15 around the molding die 13. Molding jig 15
May be arranged in an appropriate number.

A sheet 12 to be formed is formed on the dividing surface of the lower chamber 3 and the middle chamber 2 above the molding die 13 so as to be formed into a shape along the surface shape of the molding die 13. The sheet to be formed 12 is not particularly limited in material and thickness as long as it is a sheet having the same thermoformability as that conventionally used as a formed body for vacuum forming. , Polyolefin resin, acrylic resin,
It is possible to use a film or sheet made of a thermoplastic resin such as a polyester resin or an ABS resin, a multi-layer laminated sheet made of the same or different materials selected from these, a sheet made of a mixture or composite of different materials, and the like. it can.

If necessary, the sheet 12 to be formed may have a pattern such as a grain of wood by printing or the like, a concavo-convex pattern such as a conduit pattern by embossing, a coloring by wiping a concave portion of the concavo-convex pattern, or a surface. Arbitrary decoration treatment or surface treatment such as a surface protection layer for improving physical properties may be applied. In particular, when the molded sheet 12 is a decorative sheet for laminating and adhering to the surface of a decorative substrate as the molding die 13, an adhesive is previously applied to the surface on the molding die 13 side. May be.

When the sheet to be molded 12 is a transfer sheet for transferring a pattern or the like to the surface of a substrate to be decorated as the molding die 13, the molding die 1 for the sheet to be molded 12 may be used.
A transfer layer that can be peeled off from the sheet to be molded 12 is provided on the surface on the third side. There is no particular limitation on the detailed configuration of the transfer layer,
Generally, it is one layer or two or more layers selected from a release layer, a surface protection layer, a picture printing layer, a metal deposition layer, and the like, and an adhesive layer may be provided on the outermost surface.

The surface of the sheet 12 to be formed on the transfer layer side is subjected to a mold release treatment with a silicone compound or the like for ensuring the releasability of the transfer layer, and the gloss of the surface of the produced decorative material is adjusted. The surface of the manufactured decorative material may be subjected to a surface roughness adjustment process for forming the surface of the cosmetic material to be processed, or the like.

A flexible sheet 11 is stretched on the division surface between the middle chamber 2 and the upper chamber 1 above the sheet to be molded, and the upper, middle, and lower chambers are closed to prepare for vacuum molding. Is completed (FIG. 1A).

The flexible sheet 11 is depressurized on the side of the middle chamber 2 and pressurized on the side of the upper chamber 1 while the periphery thereof is clamped and fixed by a casing of a vacuum forming machine constituting the upper chamber 1 and the middle chamber 2. When pressed, it covers the inner wall surfaces of the middle chamber 2 and the lower chamber 1 and the upper surface of the molding die mounting table 14 including the molding die 13 and the molding jig 15, and a part thereof covers the surface of the molding die 13. Flexibility and rupture resistance enough to adhere along the three-dimensional shape, and heat resistance enough to withstand the temperature sufficient to soften the thermoformable molded sheet 12 into a three-dimensional shape. What is necessary is just the sheet body provided. However, due to heat during molding, the sheet to be molded 1
It is necessary to select a material or perform a surface treatment such as a mold release treatment for preventing fusion with the sheet 12 so as not to fuse with the sheet 2.

More preferably, an elastomer sheet having the property of restoring its original shape when the pressure is released is suitable for the purpose of the present invention so that it can be used repeatedly easily. In consideration of this, it is most desirable to use a silicone rubber sheet which is excellent in heat resistance, flexibility, elasticity, resilience and the like and has poor adhesion to general materials.

The flexible sheet 11 has a thickness of 0.5 to 0.5 to follow the complicated three-dimensional shape of the surface of the molding die 13.
5 mm, preferably 1-3 mm, elongation in a temperature range of 20-30 ° C. is 530% or more, and tensile strength is 7
5000 to 150,000 Pa (about 75 to 150 kgf /
cm ² ).

When the thickness of the flexible sheet 11 is less than 0.5 mm, the flexible sheet 11 may not be able to withstand stress due to heat during molding or a pressure difference between both sides, and may be broken. In addition to this, in addition to being inferior in followability to a complicated three-dimensional shape, the heat capacity is increased, the heat energy loss in each molding cycle is increased, and the molding cycle time is long, which is not practical.

If the elongation percentage of the flexible sheet 11 in the temperature range of 20 to 30 ° C. is less than 530%, the flexibility of the flexible sheet 11 is insufficient, and There is a possibility that it may be difficult to make the 11 follow the three-dimensional shape of the surface of the molding die 13 and sufficiently adhere the same. Moreover, the tensile strength of the flexible sheet 11 is 75000 Pa (about 75 kg).
f / cm ² ), it may not be able to withstand the deformation at the time of molding and may be broken.
If it exceeds (about 150 kgf / cm ² ), the flexibility of the flexible sheet 11 is inferior and the followability of the surface of the molding die 13 to the three-dimensional shape is undesirably reduced.

When the installation of each element material is completed as described above, the process proceeds to the step of heating and softening the sheet 12 to be formed. In this embodiment, the heating and softening of the sheet to be molded 12 is performed by reducing the pressure inside the upper chamber 1 and the middle chamber 2, and applying heat to the hot platen 16 as a heating means installed on the ceiling of the upper chamber 1. This is performed by bringing the molded sheet 12 into contact with the flexible sheet 11 and transmitting the heat of the hot platen 16 to the molded sheet 12 via the flexible sheet 11 (FIG. 1B).
The sheet to be molded 12 is heated to a temperature close to or higher than its glass transition temperature or softening temperature, so that the sheet 12 is softened to an extent that it can be molded along the three-dimensional shape of the surface of the molding die 13.

The step of heating and softening the sheet 12 is performed in the same manner as described above, except that the inside of the middle chamber 2 and the lower chamber 3 is maintained at substantially the same pressure, and the sheet 12 is held substantially horizontally. In the middle chamber 2 and / or the lower chamber 3, a molding die 13 is provided.
Heating means, such as a hot platen, installed so as to be able to move forward and backward between a forward position above and a retracted position retracted therefrom, can be advanced to the forward position to generate heat. As described above, a technique of heating the sheet 12 using a heating means that can move forward and backward is disclosed in, for example,
It is publicly known from Japanese Patent No. 368837 and the like. When the sheet 12 is sufficiently heated and softened, it is necessary to retreat the heating means to the retreat position before moving to a subsequent step.

After the sheet 12 to be molded is sufficiently heated and softened, the inside of the lower chamber 3 is depressurized and the inside of the middle chamber 2 is pressurized.
Is pressed against the surface of the molding die 13 (FIG. 1 (c)). At this time, the sheet to be molded 12 does not necessarily have to be faithfully formed along the three-dimensional shape of the surface of the molding die 13, and a part having a complicated shape has a part floating from the surface of the molding die 13. In short, the sheet to be molded 12
Molding conditions such as molding temperature and molding pressure may be set within a range that does not cause extreme distortion or breakage to such an extent that it cannot be used as a sheet molded product.

In particular, the sheet to be molded 12 is
A decorative sheet for laminating and bonding to a base material to be coated,
In the case of a transfer sheet for transferring a transfer layer such as a pattern to a base material to be decorated, the adhesion between the base material to be coated and the decorative sheet or the transfer layer is insufficient due to insufficient pressing force in part. It may be in a sufficient state. Further, the decorative sheet or the transfer sheet may be broken at a portion other than on the surface of the base material to be decorated, or may be broken to an inconspicuous degree even on the surface of the base material. Absent.

Thereafter, the inside of the middle chamber 2 is depressurized and the inside of the upper chamber 1 is pressurized, and the flexible sheet 11 is placed on the surface of the molding die 13 by utilizing the pressure difference between the two chambers. The molded sheet 12 is brought into close contact with the coated molded sheet 12, and the molded sheet 12 is further pressed against the surface of the molding die 13 (FIG. 1).
(D)).

By the above-described operation, even if a part of the sheet 12 to be formed is floating from the surface of the molding die 13 in the previous step, the sheet is pressed by the pressing force of the flexible sheet 11 in this step. Since the sheet 12 is pressed again to the molding die 13, the sheet to be molded 12 can be faithfully molded into a shape along the three-dimensional shape of the surface of the molding die 13.

In particular, the sheet to be molded 12 is
A decorative sheet for laminating and bonding to a base material to be coated,
In the case of a transfer sheet for transferring a transfer layer such as a pattern to a base material to be decorated, the adhesion between the base material to be coated and the decorative sheet or the transfer layer in a previous step is partially insufficient. However, in this step, the decorative sheet or the transfer sheet is again pressed against the base material by the pressing force of the flexible sheet 11, so that the adhesion between the base material and the decorative sheet or the transfer layer is sufficiently improved. can do.

When the decorative sheet or the transfer sheet is partially broken in the previous step, the pressure in the inner chamber 2 leaks from the broken portion in the previous step, and the decorative sheet or the transfer sheet is broken. Molding defects and adhesion defects are likely to occur at least around the broken portion of the transfer sheet, but even in such a case, the decorative sheet or the transfer sheet is again covered by the pressing force of the flexible sheet 11 in this step. Since the decorative sheet is pressed against the decorative base material, the decorative sheet or the transfer layer is faithfully formed along the three-dimensional shape of the surface of the decorative base material, and a decorative material sufficiently adhered to the surface of the decorative base material is obtained. be able to.

When the pressing force is applied by the flexible sheet 11 in the above process, the pressing force of the flexible sheet 11 is applied to the sheet 12 and the molding die 13 more effectively. In addition, it is desirable that the inside of the lower chamber 3 is maintained in a reduced pressure state. In particular, when the decorative sheet or the transfer sheet as the molded sheet 12 has been broken in the previous step, the air in the lower chamber 3 may be broken unless the pressure inside the lower chamber 3 is reduced. By leaking into the middle chamber 2 through the portion, the pressure difference on both sides of the flexible sheet 11 is reduced, and a sufficient pressure contact force cannot be obtained. Therefore, it is necessary to maintain the inside of the lower chamber 3 in a reduced pressure state. .

After the sheet to be molded 12 is molded along the surface of the molding die 13 in the above manner, the interiors of the upper, middle, and lower chambers are returned to atmospheric pressure, and the product of the vacuum molding machine is opened by opening the casing of the vacuum molding machine. Just take it out. In the case of a sheet molded product, the molded sheet 12 is released from the molding die 13, and in the case of a decorative material using a decorative sheet as the molded sheet 12, the decorative sheet is laminated on the decorative substrate serving as the molding die 13. The surplus portion of the molded sheet 12 is cut and removed while being kept.

In the case of a transfer decorative material using a transfer sheet as the molded sheet 12, the molded sheet 12 may be peeled off while leaving only the transfer layer adhered to the surface of the decorative substrate. An excess portion may be cut and removed without peeling and removing the molded sheet 12 from the surface of the decorative substrate, and the molded sheet 12 other than the transfer layer portion may be used as a temporary surface protection film. Note that, on the transfer layer after peeling, a suitable transparent or translucent paint is applied, or a separately prepared transparent or translucent thermoplastic resin film is again laminated and adhered by a vacuum forming method. Alternatively, a surface protective layer can be formed on the transfer layer.

[0047]

EXAMPLES Various types of thermoformable decorative sheets enumerated below were used in the vacuum forming method of the present invention and in three kinds of vacuum forming methods of a conventional method, a membrane press method and a membraneless method, as comparative examples. Were laminated and adhered to the surface of the base material having the above-mentioned shape, and the adhesive strength, the state of the molding surface, and the followability to the base material shape were evaluated. In addition, as shown in FIG. 1, the base material to be used had a shape in which a semicircular groove having a depth of 5 mm was cut in a plane portion of a rectangular plate of 4R × 4R.

Sample of decorative sheet specification list Decorative sheet composition Thickness 1 Transparent acrylic / colored acrylic 0.20 mm 2 Transparent PVC / colored PVC 0.30 mm 3 Transparent acrylic / colored olefin 0.12 mm 4 Transparent olefin / colored olefin 0.18 mm 5 Transparent olefin / colored ABS 0.19mm 6 Transparent olefin / colored acrylic 0.19mm 7 Transparent amorphous polyester / colored amorphous polyester 0.24mm 8 Olefin single layer 0.07mm 9 PVC single layer 0.08mm 10 Acrylic single layer 0.10mm

The results are shown in the following table.

(1) Sample of adhesive strength (unit: N / mm, unit in parentheses is unit: kgf / inch) Sample of the present invention Membrane press method Membraneless method 1 8.9 (2.3) 9.6 (2.5) 7.7 (2.0) 2 12.7 (3.3) 11.6 (3.0) 10.8 (2.8) 3 16.2 (4.2) 12.3 (3.2) 13.1 (3.4) 4 11.2 (2.9) 8.5 (2.2) 8.1 (2.1) 5 12.7 (3.3) 8.1 (2.1) 9.6 (2.5) 6 10.4 (2.7) 9.6 (2.5) 7.7 (2.0) 7 11.2 (2.9) 8.9 (2.3) 9.3 (2.4) 8 7.3 (1.9) 5.8 (1.5) 4.6 (1.2) 9 9.6 (2.5) 6.9 (1.8) 7.3 (1.9) 10 7.3 (1.9) 5.0 (1.3) 5.4 (1 .4)

(2) State of Formed Surface Sample Membrane Press Method Membrane Press Method Membraneless Method 1 Good Bad Bad 2 Good Bad Bad 3 Good Good Good 4 Good Good Good 5 Good Good Good 6 Good Good Good 7 Good Bad Bad 8 Good Bad Bad 9 Good Bad Bad 10 Good Bad Bad

(3) Sample that Follows Base Material Membrane Press Method Membraneless Method 1 Good Good Good 2 Good Good Good 3 Good Somewhat poor Somewhat poor 4 Good Adhesion failure Good 5 Good Somewhat poor Good Good Good Good 7 Good Good Good 8 Good Somewhat poor Somewhat poor 9 Good Good Good 10 Good Good Good

[0053]

According to the vacuum forming method of the present invention, (1) a molded article having improved conformability to a three-dimensional surface of a complex forming die and excellent shape accuracy can be obtained as compared with the conventional method. Obtained stably. (2) Vacuum forming can be performed under conditions such as the material and thickness of the sheet to be formed, the shape of the forming die, and the temperature and pressure, which were difficult to form by vacuum in the conventional method. (3) By expanding the range of molding conditions that can be molded,
Efforts to determine the molding conditions can be reduced, and molding defects can be greatly reduced. And other excellent practical effects.

In particular, in the case of a decorative sheet laminating method or a transfer method using a transfer sheet, in addition to the above effects, (4) unevenness of the surface of the base material to be coated and uneven coating of the adhesive. It is difficult to pick up the like, and a cosmetic material having a smooth surface can be easily obtained. (5) The adhesive strength between the decorative sheet or the transfer layer and the substrate to be decorative is improved. (6) Even if the decorative sheet or the transfer sheet is partially broken in the first stage of molding and defective molding or poor adhesion occurs, the second stage of molding is performed by pressing the flexible sheet again by pressing force. Can be prosthetic. And other excellent practical effects.

[Brief description of the drawings]

1 (a) to 1 (d) are explanatory diagrams showing an embodiment of a vacuum forming method of the present invention in the order of steps.

[Explanation of symbols]

 1 Upper room 2 Middle room 3・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Flexible sheet 12 ・ ・ ・ ・ ・ ・ ・ ・ ・····· Sheet to be molded 13 ······································ ···························· Hot plate

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Yumiko Tsuruta 1-5-1, Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd. F-term (reference) 4F100 AK01B AK15 AK25 AL09B AR00A AT00C BA02 BA03 BA07 BA10A BA10C EC04C EJ212 EJ242 EJ392 EJ422 HB00A JA02B JB16A JJ03B JK02B JK06 JK15 JK17B JL01 JL04 YY00B 4F208 AC03 AD10 AJ05 AJ11 MA01 MC02 MH06 MK01 MK15 MK20 4F211 AC03 AD10 AJ05 AJ11 SA02 SC01 SD01

Claims (8)

[Claims] 1. A thermoformed moldable sheet is spread on the surface of a molding die, and the molded sheet is heated and softened.
The space on the molding die side of the sheet to be molded is depressurized, and the space on the side opposite to the molding die of the molding sheet is pressurized, and the pressure difference between the two spaces is used to form the sheet on the surface of the molding die. In a vacuum forming method of forming a sheet to be formed into a shape along the surface of the forming die by pressing against the surface of the forming die, the sheet is pressed into contact with the surface of the forming die in accordance with the above procedure, and then the sheet is formed. The flexible sheet expanded on the side opposite to the mold, while reducing the space on the mold side of the flexible sheet, pressurizing the space on the opposite side of the mold for the flexible sheet, The flexible sheet is made using the pressure difference between the two spaces,
A vacuum forming method characterized by further pressing the molded sheet to the surface of the molding die by pressing the molded sheet pressed against the surface of the molding die on the surface opposite to the molding die. . 2. A vacuum forming apparatus which can be divided into three upper, middle, and lower chambers, wherein the flexible sheet is formed on a dividing surface between an upper chamber and a middle chamber, and the flexible sheet is formed on a dividing surface between a middle chamber and a lower chamber. The sheet, the molding dies are arranged on a molding die mounting table installed in the lower chamber, respectively, and while the sheet to be molded is heated and softened, the lower chamber is depressurized and the inner chamber is pressurized. Then, the sheet to be molded is pressed against the surface of the molding die by utilizing the internal pressure difference between the middle and lower chambers. Thereafter, the inner chamber is depressurized, and the upper chamber is pressurized to increase the internal pressure between the upper and lower chambers. Utilizing the pressure difference, the flexible sheet is pressed against the surface of the molding sheet pressed against the surface of the molding die, on the surface opposite to the molding die, thereby forming the molding sheet into the molding die. 2. The vacuum forming method according to claim 1, wherein the surface is further pressed against the surface. 3. The step of heating and softening the sheet to be molded includes depressurizing the upper chamber and the inner chamber and maintaining the lower chamber at a higher pressure than the upper and middle chambers through the flexible sheet. The sheet to be formed is brought into contact with a heating means provided on the ceiling of the upper chamber, and the heat of the heating means is transmitted to the sheet to be formed through the flexible sheet to heat the sheet to be formed. 3. The vacuum forming method according to claim 2, wherein: 4. The step of heating and softening the sheet to be molded includes forming the sheet in the middle and / or lower chamber while maintaining the sheet in a substantially horizontal state while maintaining the inside and lower chambers at substantially the same pressure. After the heating means is moved forward and backward between the forward position above the mold and the retracted position retracted from the former, the heating means is advanced to the forward position, and after the sheet to be molded is heated and softened, the heating means is retracted. 3. The vacuum forming method according to claim 2, wherein the substrate is retracted to a position and a subsequent process is performed. 5. The flexible sheet is pressed against the surface of the molding die by depressurizing the inner chamber and pressurizing the upper chamber, utilizing the internal pressure difference between the upper and lower chambers. Of molded sheet,
The vacuum forming method according to any one of claims 2 to 4, wherein the step of pressing against the surface on the side opposite to the molding die is performed while maintaining the lower chamber in a reduced pressure state. 6. The flexible sheet has a thickness of 0.5 to 5 m.
m, the elongation percentage in the temperature range of 20 ° C. to 30 ° C. is 530.
%, And a heat-resistant elastomer sheet having a tensile strength of 75,000 to 150,000 Pa (about 75 to 150 kgf / cm < ² >). 7. The molding die is a base material to be decorated, and the sheet to be molded is a decorative sheet of thermoformability. Along with shaping the decorative sheet into a shape along the surface of the material,
The vacuum forming method according to any one of claims 1 to 6, wherein the decorative sheet is laminated and adhered on the surface of the substrate to be decorative. 8. The molding die is a base material to be decorated, and the molding sheet is a transfer sheet having a transfer layer releasably provided on one surface of a thermoformable support sheet. The transfer sheet side of the transfer sheet is pressed into contact with the surface of the base material to be molded to form a transfer sheet in a shape along the surface of the base material to be coated, and the transfer layer of the transfer sheet is placed on the surface of the base material to be coated. The vacuum forming method according to claim 1, wherein the image is transferred onto a sheet.