JP2019123109A - Forming method of resin formed article - Google Patents

Abstract

To provide a forming method of a resin formed article that can be formed so that air does not remain between a foamed resin layer and a resin sheet layer.SOLUTION: According to the forming method of a resin formed article 10, at a step of thermocompression-bonding, with a die, a base material 15 in which a resin sheet layer 12, 13 is disposed on both front and back sides of a foamed resin layer 11, a residual bubble present between the foamed resin layer 11 and the resin sheet layer 12, 13 is discharged from the base material 15 by providing a vacant space between the resin sheet layer 12, 13 and the die before starting the thermocompression-bonding, and delaying a timing at which a peripheral portion of the base material 15 contacts with the die, from a timing at which a central portion of the base material contacts with the die, when expansion occurs due to heating by the thermocompression-bonding. The die consists of an upper die and a lower die, and at least one inner surface of the die may be formed, in the vacant space, in a convex shape which bulges in an arc toward a center from a peripheral edge of the die as corresponding with the central portion from the periphery portion of the base material.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method of molding a resin molded product in which resin sheet layers are disposed on both the front and back sides of a foamed resin layer.

  BACKGROUND ART Conventionally, a substrate using a material containing a gas has been used for various purposes such as weight reduction, heat insulation, sound absorption, and the like. For example, in Patent Document 1, when forming a resin molded product from a substrate and a film-like resin, a vacuum laminating apparatus is used to remove residual air bubbles generated between the substrate and the film-like resin, and the resin is maintained in a vacuum state. It is disclosed to form a molded article.

  Patent Document 2 discloses that lamination of an epoxy resin composition is performed using an epoxy resin curing agent and an epoxy resin curing accelerator.

Japanese Patent Application Laid-Open No. 2002-271021 Japanese Patent Application Laid-Open No. 8-73621

  However, in patent document 1 which is the formation method of the conventional substrate, in order to remove a residual air bubble, a vacuum lamination device is needed and manufacturing cost becomes high. Moreover, before forming a vacuum state, the process of welding one side of two base materials is required, and the manufacturing process was complicated.

  In patent document 2, an epoxy resin curing agent and an epoxy resin curing accelerator are needed for lamination | stacking of an epoxy resin composition, a process is complicated and it becomes high cost.

  An object of the present invention is to provide a molding method of a resin molded product which can be formed so that air does not remain between the foamed resin layer and the resin sheet layer.

  In order to achieve the above object, the method for molding a resin molded product according to the present invention comprises, in a step of thermocompression-bonding a base having three or more layers in which resin sheet layers are disposed on both sides of a foamed resin layer. Before thermocompression bonding, an air gap is provided between the substrate and the mold, and when the thermal compression bonding is performed by expansion, the timing at which the peripheral portion of the substrate and the mold contact the center portion of the substrate and the gold By delaying the timing at which the mold contacts, residual bubbles present between the foamed resin layer and the resin sheet layer are discharged from the base to the periphery.

  In the above configuration, the mold comprises an upper mold and a lower mold, and a load is applied to at least one of the upper mold and the lower mold so that the center of the inner surface is most bent to contact the substrate, or the upper mold And at least one of the lower molds is preformed in a convex shape slightly bulging in a slight arc toward the center from the peripheral edge of the base material, and is gradually brought into contact with the central portion of the base material from the peripheral edge to the timing You may shift it. It may be in the range of 40% to 60% with respect to the difference between the maximum value of the gap and the thickness of the substrate.

According to the present invention, in the step of thermocompression-bonding the substrate on which the resin sheet layer is disposed on both the front and back sides of the foamed resin layer, the peripheral portion of the substrate and the mold during expansion due to heating at the thermocompression bonding By delaying the timing of contact between the foamed resin layer and the resin sheet layer by delaying the timing of contact between the center of the substrate and the contact of the mold, residual bubbles present between the foamed resin layer and the resin sheet layer are pushed out from the center of the substrate toward the periphery. Discharged from the substrate.
In a preferred embodiment of the present invention, by making the inner surface side of the mold into a convex shape slightly projecting in the shape of an arc from the peripheral edge of the substrate toward the center, the peripheral edge side is sequentially from the center of the substrate at the time of thermocompression bonding By applying pressure, residual air bubbles present between the foamed resin layer and the resin sheet layer can be discharged from the base material. Therefore, air stagnation does not easily occur between the resin sheet layer and the foamed resin layer, and it is possible to inexpensively provide a molded resin article having a good appearance without unevenness by using the vacuum lamination method.

In the first embodiment of the present invention, while showing the deformed state of the upper mold when pressing the mold in the thermocompression bonding step, the behavior of the bubbles existing between the foamed resin layer and the resin sheet layer by the pressing Is a cross-sectional view schematically showing. It is a flowchart which shows the manufacturing method of the resin molded product of this invention. It is a top view which shows the positional relationship of a lower mold | type and a stopper. In 2nd Embodiment, it is sectional drawing which shows typically the upper mold | type which protruded in the shape of convex shape which slightly protruded in the shape of an arc toward the center from the periphery of a base material in the inner surface side. It is a top view which shows the measurement location of the space | gap in a base material. It is an optical image which shows the external appearance of the resin molded product of an Example. It is a figure which shows the measurement result of the air pool in the resin molded product of an Example. It is an optical image which shows the external appearance of the resin molded product of a comparative example. It is a figure which shows the measurement result of the air pool in the resin molded product of a comparative example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In the present embodiment, an example of a resin molded product used for a roof panel of a vehicle body will be described as a resin molded product, but the application, shape, size and the like of the resin molded product are not limited in the present invention.
The present invention relates to a method for producing a resin molded product, in particular, when forming a resin molded product by laminating a foamed resin and a resin sheet, air bubbles are generated at the interface between the foamed resin and the resin sheet in the heating and pressing step. The present invention relates to a technique for obtaining a high-quality and good-looking resin molded product without remaining.
Referring to FIG. 1, when upper die 21 is lowered relative to base material 15 and uniformly pressed horizontally, air bubbles 18 present between the foamed resin layer 11 of base material 15 and resin sheet layer 12 are interfaces. It is molded while being confined in the If molding is performed with the air bubbles 18 remaining, the appearance of the resin molded product 10 is deteriorated and the quality is impaired. Therefore, in the present invention, when expanding due to heating at the time of thermocompression bonding, the timing at which the mold 20 contacts the peripheral portion of the substrate 15 is delayed from the timing at which the mold contacts the central portion of the substrate. The residual air bubbles 18 present between the layers 11 and the resin sheet layer 12 are discharged from the substrate 15.
When shifting the timing of contact of the mold with the central portion and the peripheral portion of the substrate, as shown in FIG. 1, for example, the upper mold 21 of the mold is gradually contacted from the central portion of the substrate 15 toward the peripheral portion As shown in FIG. 4, the inner surface of the upper mold 21 is gradually curved from the center to the periphery of the substrate 15, for example, as shown in FIG. 4. You may shape | mold by any of the method (2nd Embodiment) pressed using the metal mold | die previously formed in convex shape.
Hereinafter, the present invention will be further described based on specific embodiments.

First Embodiment
FIG. 1 is a cross-sectional view showing a state in which a base material 15 for obtaining a resin molded product 10 according to a first embodiment of the present invention is housed and pressurized in a mold 20 of a thermal pump molding machine.
As shown in FIG. 1, the base material 15 is accommodated in the mold 20 of the heat press molding machine. The resin molded product 10 molded by the base material 15 is a molded product in which the first resin sheet layer 12 and the second resin sheet layer 13 are stacked and arranged on both the front and back sides of the foamed resin layer 11.
The first resin sheet layer 12 and the second resin sheet layer 13 are configured to include a film, a film, a plate and the like attached to the foamed resin layer 11.

  As a material constituting the foamed resin layer 11 and as materials constituting the first and second resin sheet layers 12 and 13 disposed on the front and back sides of the foamed resin layer 11, the foamed resin layer 11 is used as a first resin sheet layer Any material can be used as long as the foamed resin layer 11 can be welded between the resin sheet layers 12 and 13 by heating and pressurizing from the outside of the 12 and the second resin sheet layer 13.

  As a material of the foamed resin layer 11, for example, a thermoplastic resin such as urethane or sponge can be used.

  As a material of the 1st resin sheet layer 12 and the 2nd resin sheet layer 13, thermoplastic resins, such as polypropylene (PP), can be used, for example.

  By heating the base 15 placed in the heat press molding machine, the foamed resin layer 11 sandwiched between the resin sheet layers 12 and 13 thermally expands. The expansion force due to the heating of the foamed resin layer 11 is forcibly brought into a stationary state by pressing the upper mold 21, whereby the internal pressure of the foamed resin layer 11 causes the first resin sheet layer 12 and the second resin sheet layer 13. And the foamed resin layer 11 sandwiched therebetween are pressure-welded and heat-welded.

FIG. 2 is a flow chart showing the method for producing the resin molded product 10 of the present invention.
As shown in FIG. 2, the production of the resin molded article 10 of the present invention is performed by the following steps.
Step 1: The first resin sheet layer 12 and the second resin sheet layer 13 are stacked on both the front and back sides of the foamed resin layer 11 to form a laminate 15, which is used as the mold 20 of the heat press molding machine. Housed inside. The heat press molding machine comprises upper and lower molds 21 and 22 which can be divided up and down, and the upper mold 21 and the lower mold 22 are provided with the stopper 25 around them to form a predetermined gap G inside the mold. (See FIG. 4). The substrate 15 is placed on a predetermined position of the lower mold 22 of the heat press molding machine, and the mold is closed (mold closing).
Step 2: The base 15 is heated and pressurized to a predetermined temperature and a predetermined pressure in the upper and lower molds of the heat press molding machine. Hot pressing by a thermal press molding machine is also called thermocompression bonding.
Step 3: The hot pressed base material 15 is taken out of the mold 20, inserted into a predetermined position of a cold press, and cooled to room temperature, whereby the resin molded product 10 can be formed.

  FIG. 3 is a plan view showing the positional relationship between the lower mold 22 and the stopper 25. As shown in FIG. As shown in FIG. 3, the stoppers 25 are disposed at two positions on the long side of the upper surface of the lower mold 22, that is, two sides on the outer peripheral side of the lower mold 22, and the base 15 is inside the stopper 25. It is placed.

  In the first embodiment of the present invention, as shown in FIG. 1, the mold 20 is composed of an upper mold 21 and a lower mold 22. The mold 20 has a gap G of a predetermined size between the lower surface of the upper mold 21 and the upper surface of the base 15 by the stopper 25 disposed around the upper surface of the lower mold 22 as shown in FIG. ) Are provided. The gap G is, for example, a gap of 2 mm when the height of the stopper 25 is 12.0 mm and the height of the base 15 is 10.0 mm.

  In the present embodiment, the upper die 21 is gradually pressed from above to the periphery by pressing means so that the upper die 21 contacts the center part faster than the periphery of the base material 15. Be done. Therefore, a load is applied from above while bending the central portion of the upper mold 21 downward, that is, convexly toward the side of the base material 15 by the pressing means. Thus, the upper die 21 protrudes downward in a slightly arc shape from the center to the periphery, and first, as the foamed resin layer 11 of the base 15 expands, the central portion of the upper die 21 is a resin sheet layer Then, the periphery of the upper mold 21 contacts the periphery of the substrate 15 gradually, and finally, the peripheral portion of the upper mold 21 is brought into contact with the periphery of the upper mold 21 as shown in FIG. The peripheral portion is pressurized. At this time, the air bubbles 18 present between the foamed resin layer 11 of the substrate 15 and the resin sheet layer 12 due to expansion gradually move from the central portion of the substrate 15 toward the peripheral portion, and the peripheral edge of the interface It will be discharged from and completely adhered.

  In FIG. 1, the deformed state of the upper mold 21 when the mold 20 is pressurized in the thermocompression bonding process is shown in a cross-sectional view. As shown in FIG. 1, when the upper die 21 is pressurized, the air gap G around the upper die 21 becomes larger, and the gap in the center of the upper die 21 is bent in an arc shape so as to narrow. That is, when the upper mold 21 is pressurized, the upper mold 21 is deformed so as to be bent convexly toward the base material 15. In the present embodiment, the pressing means uses the upper die 21 which is convexly curved in a spherical shape all around downward, and the central portion that protrudes most below the upper die 21 faces the central portion of the substrate 15. It is made to be arranged.

FIG. 1 also schematically shows the behavior of the foamed resin layer 11 due to pressure in the thermocompression bonding step of step 2.
As shown in FIG. 1, the foamed resin layer 11 sandwiched between the resin sheet layers 12 and 13 of the base material 15 is expanded by heating and pressing. As the foamed resin layer 11 expands, the foamed resin layer 11 and the first resin sheet layer 12 disposed on the upper side come in contact with the surface of the upper mold 21. Then, air bubbles (interlayer air) 18 remain in the interlayer between the foamed resin layer 11 and the first resin sheet layer 12.

  Here, when the residual air bubbles 18 present between the layers can not be discharged from the base material 15, air is entrained between the first resin sheet layer 12 and / or the second resin sheet layer 13 and the foamed resin layer 11. A so-called air reservoir is formed. The air reservoir 18 is formed at the interface of the first resin sheet layer 12 and the foamed resin layer 11 to be in close contact. When the air reservoir 18 is formed on the base material 15, a decrease in interface strength and a convex portion on the design surface occur. The design surface is a surface on which the first resin sheet layer 12 or the second resin sheet layer 13 is viewed. In FIG. 1, the first resin sheet layer 12 is a design surface. The air reservoir 18 remains in various sizes of 10 mm or less, 10 to 20 mm, 20 to 30 mm, and 30 to 40 mm, which is not preferable because the appearance of the design surface is deteriorated.

However, in the present embodiment, since the residual air bubbles 18 present at the interface are discharged by pressure from the center of the surface of the upper mold 21 forming the spherical gradient toward the outer peripheral part, the residual air bubbles present at the interface are While all are discharged, the base material 15 is closely adhered by thermocompression bonding, and the resin molded product 10 without air accumulation can be formed. Thereby, in the thermocompression bonding step of step 2, residual bubbles present between the foamed resin layer 11 and the resin sheet layers 12 and 13 at the time of thermocompression bonding can be discharged from the base material 15.
Therefore, in the present embodiment, even if the base material 15 is a large-area base material that is applied to, for example, the roof of a vehicle, or is formed in a multilayer structure with a thickness of three or more layers, The residual air bubbles can be reliably discharged. On the other hand, in the conventional method of discharging the air between the layers locally by means of a roll and discharging it, the material is limited to a thin material, but in this embodiment, regardless of the area of the base, the base Applicable regardless of the thickness of the

  The gap G is preferably smaller than the difference between the thickness of the stopper 25 and the thickness of the substrate 15. For example, if the thickness of the stopper 25 is 12 mm and the thickness of the base 15 is 10 mm, the difference is 2 mm. Here, the maximum value of the gap G is the thickness of the stopper 25, that is, the maximum value of the gap G determined by the upper and lower molds.

  By adjusting the space G between the upper mold 21 and the substrate 15 by pressing the mold, the degree of discharge of the residual air bubbles 18 is different. The space G where the residual air bubbles 18 are completely discharged is, for example, about 0.8 mm to 1.2 mm. The value of the air gap G is about 40% to 60% with respect to 2 mm which is the difference between the thickness of the stopper 25 which is the maximum value of the air gap G and the thickness of the substrate 15. That is, the gap G where the residual air bubbles are completely discharged is about 40% to 60% with respect to the difference between the maximum value of the gap G (the thickness of the stopper 25) and the thickness of the substrate 15. If this value is 0.7 mm, that is, 35% or less with respect to 2 mm, the air gap G becomes small, and an air pool described later is generated, which is not preferable. On the contrary, when the value of the gap G is 1.3 mm, that is, 65% or more with respect to 2 mm, the layer between the foamed resin layer 11 and the resin sheet layers 12 and 13 is not adhered, which is not preferable.

Second Embodiment
As shown in FIG. 4, in the second embodiment of the present invention, unlike the first embodiment shown in FIG. 1, the inner surface of the mold 20 is formed in a convex shape. This convex shape may be provided on the inner surface of both the upper and lower molds, or may be formed on at least one of the inner surfaces of the upper and lower molds. In any case, since the upper and / or lower molds of the mold are formed in a slightly arc shape toward the substrate 15, the pressure necessary for thermocompression bonding and the discharge of residual air bubbles are necessary. The residual air bubbles can be discharged from the substrate 15 by such pressure.

  According to the present invention, the adhesion and lamination of the base material 15 can be formed only by the heat press molding machine and the cold press machine. As a result, the material for the vacuum device and the extra adhesive becomes unnecessary, so that the resin molded product 10 can be molded at low cost.

  According to the present invention, there is no need to weld one side of the first resin sheet layer 12 or the second resin sheet layer 13, and lamination becomes possible, and it is possible to form the resin molded article 10 by a simple process. Become.

The resin molded article 10 of the present invention is not only a roof panel of a vehicle body, but also a door panel, an instrument panel, a pillar part, a trim part, an engine room part, an exterior part, a ceiling panel, a bumper, a side molding, as interior products. It can be used for air spoiler etc.
Hereinafter, the present invention will be described in more detail by way of examples.

A first resin sheet layer 12 and a second resin sheet layer 13 made of polypropylene and having a thickness of 1 mm are laminated on both the front and back sides of the foamed resin layer 11 made of urethane and having a thickness of 8 mm. The substrate 15 is 10 mm in diameter. The dimensions of the mold 20 and the base 15 of the hot press and cold press are shown below.
Dimension of mold 20: 2500 mm × 1500 mm
Dimensions of substrate 15: 2000 mm × 1300 mm

The conditions of the hot press and cold press are shown below. Hot press: A pressure of 13.2 MPa was applied at 165 ° C.
The pressing time may be appropriately set according to the thickness and the area of the substrate 15.
Cold press: at 20 ° C., a pressure of 13.2 MPa was applied.
The pressing time may be appropriately set according to the thickness and the area of the substrate 15.

The gap G in the hot press when a pressure of 13.2 MPa was applied was measured using an elastic body.
FIG. 5 is a plan view showing the measurement site of the air gap G in the base material 15.
As shown in FIG. 5, (1) to (5) in the vertical direction (Y direction) of the center of the substrate 15 placed on the lower mold 22 and in the horizontal direction (X direction) from the center of the substrate 15 6) At each point of (9), the space G at the time of pressure was measured using an elastic body consisting of a sphere or a cylinder. The measurement result of the space | gap G in the pressurization of an Example is shown to a table | surface.

The gap G of (2), (3), (4), (7), (8), which is a measurement point within a width of 0.4 m, is 1 m across the central portion side of the base material 15, 10.5 is It was -10.6 mm.
On the other hand, the gap G of (1), (5), (6), (9) which is the measurement point of the end of the base material 15 is 11.1 to 11.7 mm, and the gap G is smaller than the central portion side. It turned out that it was big. The maximum value of the air gap G was 11.7 mm, and the minimum value was 10.5 mm. The difference between the maximum value and the minimum value was 1.2 mm.

FIG. 6 is an optical image showing the appearance of the resin molded product 10 of the example.
As shown in FIG. 6, in the resin molded product 10 of the example, no blister was generated on the surface of the first resin sheet layer 12. Although an air reservoir 10 mm or more can be measured by visual inspection, an air reservoir smaller than 10 mm can not be visually recognized by the visual inspection of the surface of the first resin sheet layer 12. Therefore, the number of air reservoirs 18 smaller than 10 mm was measured by visual inspection after peeling off the first resin sheet layer 12.

FIG. 7 is a view showing the measurement results of the air pool 18 in the resin molded product 10 of the example. The horizontal axis indicates the embodiment and a comparative example to be described later, and the vertical axis indicates the number of small air reservoirs 18 of 2 to 7 mm.
As shown in FIG. 7, in the resin molded product 10 of the example, the number of air reservoirs 18 of 2 to 7 mm is seven, which is a number that does not affect the appearance in practical use.

(Comparative example)
A resin molded product 10 was molded in the same manner as in the example except that the pressure of the hot press was 2.8 MPa.

As a result of measuring the space | gap G at the time of the pressurization of a hot press, it is a measurement point within 0.4 m in width 1m by the side of center part of the base material 15, (2), (3), (4), ( The gaps G of 7) and (8) were 11.2 to 11.4 mm.
On the other hand, the gap G of (1), (5), (6), (9) which is the measurement point of the end of the base material 15 is 11.6 to 11.9 mm, and it is slightly smaller than the center side. It turned out that the space | gap G is large. The maximum value of the air gap G was 11.9 mm, the minimum value was 11.2 mm, and the difference between the maximum value and the minimum value was 0.7 mm (see FIG. 6). From this, it was found that the air gap in the upper mold 21 of the hot press when the pressure of 2.8 MPa of the comparative example was applied was small on the central side and slightly increased on the peripheral side.

FIG. 8 is an optical image showing the appearance of the resin molded product 10 of the comparative example.
As shown in FIG. 8, in the resin molded product 10 of the comparative example, appearance blistering occurs on the surface side of the first resin sheet layer 12, a large number of air reservoirs 18 of 2 to 7 mm remain, and 10 mm or more The air reservoir 18 also remained.

FIG. 9 is a view showing the measurement results of the air pool 18 in the resin molded product 10 of the comparative example. The horizontal axis is the dimension (mm) of the air reservoir 18 and the vertical axis is the number of air reservoirs 18.
As shown in FIG. 9, 781 air reservoirs 2 of 2 to 7 mm with no blisters remained, and 18 air reservoirs 18 with blisters of 10 mm or more in size remained. There were 6 10-20 mm appearance blisters, 9 20-30 mm appearance blisters, and 3 30-40 mm appearance blisters.

  As described above, according to the embodiment, the difference between the maximum value and the minimum value of the gap G of the mold 20 generated at the time of pressing by the hot press is about 1.2 mm, compared to the air according to the comparative example. It was found that the resin molded product 10 having almost no stagnation 18 can be molded.

The above embodiment can be appropriately modified within the scope of the present invention.
For example, although the said embodiment demonstrated the example whose resin molded article 10 is a rectangular shape, the shape of the resin molded article 10 may be another shape.

  In the above embodiment, three of the first resin sheet layer 12 constituting the surface, the second resin sheet layer 13 constituting the back surface, and the foamed resin layer 11 disposed between the two resin sheet layers 12 and 13 Although the resin molded product 10 having a layered structure has been described, it is not particularly limited. For example, another layer may be laminated | stacked between the both resin sheet layers 12 and 13, or the outer side, and the resin molded article of four or more layers may be sufficient.

  Although the said embodiment demonstrated the example which used the plate-shaped body as the base material 15 before shaping | molding, it is also possible to use as a base material 15 shape | molded in various shapes.

10: resin molded product 11: foamed resin layer 12: first resin sheet layer 13: second resin sheet layer 15: substrate 18: air reservoir 20: mold 21: upper mold 22: lower mold 25: stopper G: gap

Claims (3)

In a step of thermocompression-bonding a base material having a resin sheet layer disposed on both sides of a foamed resin layer with a mold,
Prior to thermocompression bonding, an air gap is provided between the substrate and the mold;
In the case of expansion due to heating at the time of thermocompression bonding, the timing at which the peripheral portion of the substrate and the mold come in contact with each other is delayed from the timing at which the central portion of the substrate and the mold come in contact. A method for molding a resin molded product, comprising discharging residual air bubbles present between the resin sheet layer and the base material from the substrate.   The invention is characterized in that the mold comprises an upper mold and a lower mold, and the inner surface of at least one of the upper mold and the lower mold is formed in a convex shape which bulges in an arc toward the center from the periphery of the substrate. The molding method of the resin molded article of 1 statement.   The method according to claim 1, wherein the void is in the range of 40% to 60% with respect to the difference between the maximum value of the void and the thickness of the substrate.