JPS5949913B2 - Vacuum forming process for composite products - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a vacuum forming process for composite products, and in particular, uses vacuum or reduced pressure to press a thermoplastic skin material onto a base member of a predetermined shape and to bond them together. When bonding and integrating with an agent, air is effectively removed from between the base member and the skin material,
To provide a method that solves the so-called blister problem caused by air being trapped between them, and thereby obtains a composite product excellent in appearance and performance. It is something.

In automotive interior materials, such as the upper pad of a dashboard, a soft thermoplastic or is a composite product covered with a semi-rigid plastic sheet (skin material), which is often used for its intended purpose.

In addition, the skin material serves as a cosmetic, and if a foamed sheet or the like is used as the material, it can have cushioning properties and have functions such as absorbing or dispersing energy in the event of an impact such as a vehicle collision. It becomes possible to have the equipment equipped. On the other hand, one method of obtaining a composite material by bonding and integrating a skin material onto such a base member is to press the skin material onto a predetermined base member using vacuum or reduced pressure, and to A vacuum forming method is being considered in which they are bonded together using an adhesive. In this vacuum forming process, for example, as shown in FIG. 1, a base member 2 that becomes the core material of the product is placed on a vacuum forming mold or stand 1 having an intake line 6 connected to a vacuum source or a reduced pressure source. After attaching the base member 2 in a removable manner, a skin material 4 usually made of a thermoplastic resin as a cosmetic material is heated and softened, and then the skin material 4 is covered with the base member 2 by suction of air through the intake line 6. By removing the air between the base member 2 and the skin material 4 through the air vent hole 5 provided through the base member 2, the skin material 4 is removed from the base member as shown by the dashed line in the figure. 2 are molded into the shape of 2 and are pressed (adhered) to each other, and the adhesive 3 applied to the base member 2 or the skin material 4 is used to bond them together. However, when manufacturing the above-mentioned composite products using such a vacuum forming process, there is no adhesion between the base material to be polymerized and the skin material, unlike normal vacuum forming methods that do not aim for adhesion. Because they are bonded together by intervening an agent, this has led to disadvantageous problems. In FIGS. 2a and 2b, such a malfunction situation is illustrated in an extreme situation. That is, as shown in these figures, a heated and softened skin material 4 is placed on a predetermined base member 2 via three layers of adhesive, and air is removed by suction through an air vent hole 5 to remove the base member. 2 and the skin material 4 and attempt to bond them together, the skin material 4 first tries to adhere to the base member 2 in the vicinity of the air vent hole 5 due to the suction action through the air vent hole 5. Adhesion between the base member 2 and the skin material 4 begins from there due to the adhesive 3 present in the vicinity of the air vent hole 5. Therefore, if the base member 2 and the skin material 4 are bonded together at the air vent hole 5 first, the adhesive 3 interposed in that area acts as a packing agent and the air vent hole 5 is bonded to the base member 2 and the skin material 4. In order to prevent the flow of air to the hole 5, the air a existing between the base member 2 and the skin material 4 at a distance from the air vent hole 5 does not lose its way to escape, and the air a exists between them. Therefore, due to the trapped air a, so-called pristars in the form of swollen blisters are generated in the skin material 4 as shown in the figure, and the base member 2 and the skin are Not only does it become difficult to uniformly and integrally bond the material 4, but it also significantly deteriorates the appearance of the resulting composite product, lowering its commercial value, and also adversely affecting the performance of the composite product, such as a decrease in adhesive strength. This also causes problems. In this way, in the conventional method of adhering together with the vacuum forming process, plisters, which are considered to be essential to the method, occur, and as a result, it is difficult to completely bond the base material and the skin material together. It was extremely difficult to do so. The present invention has been made against the background of the above, and its gist is to press a skin material onto a base member of a predetermined shape using the vacuum forming method and to When bonding them together with an adhesive to form a composite product, fine particles are scattered on the surface of the adhesive applied to the base member and/or the skin material. A space supported by the granular material is temporarily formed between the base member and the skin material, and air between the base member and the skin material is guided to the air vent hole in the presence of the space. (In addition, the granular material is embedded in the adhesive layer by the pressure bonding action of the skin material, and the space is eliminated.) This effectively solves the problem of pristine formation. Therefore, it became possible to provide a composite product with excellent appearance and performance and high commercial value.

As described above, the present invention achieves excellent effects simply by dispersing fine particles on the surface of the adhesive coating layer, and does not require any other special or complicated The main feature of this method is that it does not employ any method or mechanism, but specifically, for example, while the skin material is heated to soften it, an adhesive is applied in advance to a base member of a predetermined shape, After a certain degree of drying if necessary, fine particles are scattered on the surface of the adhesive coating layer and adhered thereto, and then the adhesive is coated on the base material on which the fine particles are distributed. This will be carried out by covering with the softened skin material and vacuum forming. In addition to this method, an adhesive may be applied to the skin material before or after the skin material is heated and softened, and predetermined fine granules are sprinkled on the surface of the skin material so as to cover the base member. It is also possible to adopt methods such as the following. Due to the granules scattered on the surface of the adhesive, a granule layer is interposed between the overlapping skin material and the base member in addition to the adhesive layer. Therefore, the gaps between each of the particles in the particle layer form countless air passages, and through these air passages, the air between the skin material and the base member is effectively sucked into the air vent hole and removed. As a result, the skin material and the base member do not come into close contact with each other in the vicinity of the air vent hole first, unlike in the past, and therefore air is trapped between them and causes blisters. Without any problems, uniform and integral adhesion between the base member and the skin material could be achieved. That is, according to the present invention, as shown in FIG. 3a, for example, the adhesive 3 applied on the base member 2
After the fine granules 7 are sprinkled on the surface, when the heat-softened skin material 4 is placed on the surface, three layers of adhesive and seven layers of granules are first applied between the base member 2 and the skin material 4. By intervening, a space supported by the granules 7 is temporarily formed between them, and the air existing between them is released through countless gaps 8 (air passages) in the 7 layers of the granules. is removed by suction through an air vent hole 5 provided through the base member 2, and then the skin material 4 is removed by suction.
It is believed that the particulate matter 7 is embedded in the three layers of adhesive due to the adhesion (pressure bonding) action of the adhesive, as shown in Figure 3b, and for this reason, the particulate matter 7 that has been scattered may cause damage to the epidermis. Material 4
No unevenness is formed on the base member 2, and a uniform adhesive surface is obtained.
The adhesion between the material and the skin material 4 is not affected in any way.

In particular, such effects can be achieved by using the granules 7 according to the invention.
This can be achieved only by dispersing the adhesive, and cannot be expected at all by, for example, mixing granules into the adhesive in advance and applying it. Also,
As the adhesive applied to the base member or skin material according to the method of the present invention, any known adhesive that meets the purpose of the present invention may be used, but the adhesive as described above (
(See Figure 3b) If you want to effectively embed the dispersed particles, use a hot-melt adhesive that melts when heated and its viscosity decreases. It is recommended that you use it.

However, if you use such heat-melting adhesive, the third
In the process shown in Figure a, the three adhesive layers absorb heat from the skin material 4 that has been softened by heating and melt, so that the pressure on the skin material 4 due to air suction through the air vent holes 5 and Working together, the particulate matter 7 sprinkled on its surface is effectively pushed into the third layer of adhesive, thereby forming the third layer.
This is because the particles 7 are ultimately completely embedded in the three layers of adhesive as shown in Figure b. In addition, the adhesive is applied to both the base member and the skin material, and granules are sprinkled on at least one of them,
Spraying a microcapsule adhesive or the like together with or in place of the granules, covering this with a skin material, and then destroying the microcapsules by appropriate means to develop adhesive strength. etc. are also possible. Furthermore, in consideration of the adhesive strength required between the base material and the skin material, a type of adhesive that increases the adhesive strength by naturally curing over time after they are crimped and bonded together. In some cases, it may be desirable to choose an adhesive. Furthermore, the fine particles to be sprinkled on the surface of the adhesive coating layer according to the present invention include inorganic fine particles such as silica and calcium carbonate, PVC particles obtained by emulsion polymerization, and granulated polypropylene (PP) particles. ) There are organic fine particles such as organic polymer particles, and while these fine particles are selected and used as appropriate depending on the purpose, their shapes can also be arbitrarily adopted, from spherical beads to irregularly shaped crushed ones. It can be done.

In addition, the particle size of such granules is generally determined appropriately depending on the thickness and type of the adhesive coating layer, the thickness and quality of the skin material, etc., and is difficult to define unambiguously. However, it is generally desirable that the thickness be in the range of approximately 40μ to 200μ. In addition, the use of granules with a particle size that is too large will cause unevenness in the skin material and deteriorate the appearance of the product, and the use of granules with a particle size that is too small may not fully achieve the object of the present invention. Because it will disappear. Furthermore, it is desirable that such fine particles be heat resistant; however, the heat resistance is limited by the fact that when the heat-softened skin material is applied and the air is removed by suction, the particles become resistant to heat. It is sufficient that the particles are not destroyed, and after the air is removed by suction, the granular material is removed. It is also possible to destroy the variable contract by adopting appropriate means such as: In particular, when microcapsules such as adhesives are used as described above, the microcapsules may be destroyed by appropriate means after the air between the base member and the skin material is removed by suction. It will be necessary. Furthermore, the space temporarily formed between the base member and the skin material due to the interposition of such granules depends on the shape of the base member, the degree of softening of the skin material, and even the thickness of the adhesive layer. In any case, after the air between the base member and the skin material is removed by suction, the dispersed layer of such particles will be buried in the adhesive layer. Since the particulate material can be inserted into the adhesive layer, the particulate material will be dispersed at a thickness that allows it to be embedded in the adhesive layer. In addition to what has been described above, various modifications and improvements can be made to the present invention without departing from the spirit of the present invention.

For example, all the materials conventionally used in composite products such as the present invention can be used as the base member and the skin material, and a foamed sheet consisting of a skin part and a foamed part can also be used as the skin material. be. Furthermore, the air vent holes provided in the base member will also be arranged at the same pitch as in the prior art. Further, the excellent effects of the present invention as described above have been confirmed in representative examples of the present invention described below.

That is, the insert core (core material) as the base member has holes (1) as air vent holes at approximately 40 to 50 pitch.
-Φ) was opened, and then set in a vacuum mold as shown in FIG.

Next, after coating this insert core with a heat-melt type commercially available adhesive, polypropylene (PP) powder (150 mesh passes, approximately 105μ or less) is applied on top of it.
was spread over the entire surface. Then, after covering the insert core on which the PP powder has been sprinkled with a skin material made of a PVC/ABs blend that has been separately heated and softened, the insert core is Vacuum forming was performed by suctioning and removing air from the air vent hole, and the insert core was then cooled to solidify the adhesive to achieve physical adhesion between the insert core and the skin. P on the thus obtained insert core
In the composite product in which the VC/ABS blend skin material is bonded, there is no occurrence of pristine at all, and the core and skin material are evenly bonded, so
It was observed that the adhesive force between them was approximately comparable to that without sprinkling PP powder.

As described above, the present invention provides a method for obtaining a composite product by integrally forming a base member and a skin material through an adhesive using a vacuum forming process, by simply applying the adhesive to the surface of the applied adhesive. By simply dispersing fine granules, we have completely eliminated the problem of blistering, which was previously thought to be difficult to solve.
Moreover, it enables uniform and integral adhesion of the base member and the skin material, thereby improving the product appearance and physical properties of the product, and significantly increasing its commercial value.This is a major feature of the present invention. It has the following.

[Brief explanation of the drawing]

Figure 1 is a diagram for explaining an example of a vacuum forming process, Figure 2a is a diagram showing a part of the cross section of a composite product produced by a conventional pristar, and Figure 2b is a diagram showing the A in Figure 2a. Enlarged view of part,
FIGS. 3a and 3b are partial cross-sectional views for explaining the vacuum forming process according to the present invention, respectively. 1: Vacuum forming mold, 2: Base member, 3: Adhesive, 4: Skin material, 5: Air vent hole, 6: Intake line, 7: Granular material,
8: Air passage.

Claims (1)

[Claims] 1. A base member of a predetermined shape is covered with a heat-softened skin material via an adhesive, and air present between the base member and the skin material is sucked through an air vent hole provided in the base member. In a vacuum forming process for a composite product, the skin material is pressed onto the base member along its shape by removing the skin material, and the skin material is bonded to the base member and/or the skin material. Fine particles are scattered on the surface of the applied adhesive so that a space supported by the particles is temporarily formed between the base member and the skin material. The air between the base member and the skin material is guided to the air vent hole in the presence of a space, and the particulate matter is embedded in the adhesive layer by the pressure bonding action of the skin material. A method for vacuum forming a composite product, characterized in that the space is made to disappear.