JPH0459126B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a method for manufacturing a foamed product with a core material, and particularly relates to a method for manufacturing a foamed product with a core material that can advantageously improve and stabilize product quality. It is.

(Prior Art) Foam products with a core material, which have been conventionally used in vehicle interior parts, such as pads such as safety pads, cushions, and glove doors, are generally used as reinforcing materials or as attachment materials to structural members. It has a shaped core material and a foam layer of a predetermined thickness formed by foam molding on one side of the core material, and a predetermined foam material is foamed in the presence of the core material in a predetermined foam mold. It is foam-molded by pressing.

However, in such foamed products with a core material, the shape of the core material is generally relatively complex, and since it is equipped with mounting bolts, etc., it is not possible to completely adhere it to the inner surface of the foam mold. First, there was a problem in that the foam material got around to the back side of the core material (the side on which the foam layer was not formed), causing so-called urethane leakage and causing a lot of burrs. be.

Therefore, the applicant of the present application first proposed the
In Publication No. 120421, a film covering the core material is applied to the surface of the core material on which the foam layer is formed, and the core material is foamed while being placed in a foam mold. A method for producing a foamed product with a core material has been clarified in which the material is foamed to prevent the foam material from going around to the back side of the core material with the film.

(Problem) However, in this production method, when forming the foam layer, there is no particular problem in the discharge of air existing in the foaming space of the foaming mold or gas generated during the foaming operation to the outside of the foaming space. not considered,
As the coating applied to the core material is usually a sheet made of synthetic resin materials such as hard PVC, ABS resin, and polystyrene,
Product defects are likely to occur due to loose skin, voids, air traps, etc. due to residual air or foaming gas in the foaming air, and non-uniform foaming due to increased internal pressure in the foaming space, making it difficult to maintain product quality. However, there was still room for improvement.

In addition, as a technique for preventing voids etc. in foamed products, as disclosed in Japanese Patent Laid-Open No. 53-23359, there has been a technique that does not allow the undiluted solution of foamable resin to pass through the surface of the product, but gas A known method is to provide an air-permeable coating and perform a foaming operation within the coating.

However, when trying to apply such technology to foamed products with a core material as described above,
Since it is necessary to adhere the coating to the core material, the material of the coating is limited depending on the type of adhesive used, etc., and especially for large products or products with opening holes in the core material, it is difficult to adhere the coating to the core material. In addition, defects such as misalignment and wrinkles of the film are likely to occur during the process, and the bonding operation is troublesome and time-consuming, and defects due to incomplete bonding are unavoidable. It was extremely difficult to convert.

(Solution Means) Here, the present invention has been made against the background of the above-mentioned circumstances, and its feature is that a predetermined portion of the core material is fixed to a core material having a predetermined shape. A foam layer is integrally formed on one side of the core material by applying a film to cover it and foaming the foam material while the core material is placed in a foam mold. When manufacturing a foamed core product, a breathable sheet having continuous holes that allows gas to flow but does not substantially allow the foamed material to flow is used as the coating, and the breathable sheet is used in the molding process for forming the core material. Under the condition that it is placed in a predetermined position in the mold,
By filling the core material with a predetermined resin material and molding the core material, simultaneously with the molding of the core material, the breathable sheet is applied to the side of the core material on which the foam layer is formed or on the side where the foam layer is not formed. After the core material to which the breathable sheet was adhered was placed in the foam mold, the foam layer was foam-molded.

(Effects of the Invention) Therefore, in the method of the present invention, the gas is used as a coating that is attached to the core material and prevents the foam material from going around during the foaming operation and prevents urethane leakage. Since a breathable sheet is used that has continuous holes that allow the foaming material to flow through but not substantially prevent the foaming material from flowing, such a breathable sheet prevents urethane leakage during the foaming operation, and allows residual air and foaming gas in the foaming space to be absorbed. Through
It can be effectively discharged out of the foaming space, thereby effectively preventing the occurrence of product defects due to loose skins, voids, air traps, etc., and making it possible to achieve uniform foaming. Improvement and stabilization of product quality can be advantageously achieved.

Furthermore, according to the method of the present invention, since the breathable sheet is fused and attached to the core material at the same time as the core material is formed, the breathable sheet can be fused and adhered to the core material. It is possible to stably obtain sufficient adhesive force to the core material of the breathable sheet, and the material of the breathable sheet is not restricted by the type of adhesive used.

Moreover, according to the method of the present invention, simply by placing the breathable sheet at a predetermined position within the mold for the core material, the breathable sheet can be reliably positioned with respect to the core material. The occurrence of misalignment and wrinkles in the breathable sheet with respect to the core material can be almost completely prevented.

(Examples) Hereinafter, in order to clarify the present invention more specifically, examples of the present invention will be described in detail with reference to the drawings.

First, FIGS. 1 and 2 show an automobile safety pad 10, which is a foam product with a core material, manufactured by the manufacturing method according to the present invention in this embodiment. Further, FIGS. 3 to 6 each show a manufacturing process diagram of the safety pad 10 according to the method of the present invention.

That is, when manufacturing such a safety pad 10, first, as shown in FIG. 3, a skin 12 constituting the surface of the product and a core material 14 serving as a reinforcing material and a mounting material are separately formed. That will happen.

The skin 12 is formed using a synthetic resin material such as vinyl chloride by a method such as vacuum forming to have a shape corresponding to the surface shape of the front side of the safety pad 10 as a product.

In addition, the core material 14 is generally formed by a suitable molding method such as injection molding using a predetermined resin material, and is an opening forming part used as a mounting bolt 16, a grab box, an air duct, etc. 18, etc., and is formed in a predetermined shape. In addition, in the figure, 20 is a molding hole formed by injection molding of the core material 14.

As shown in FIG. 3, these skin 12 and core material 14 are inserted into a foam mold 26 consisting of an upper mold 22 and a lower mold 24, respectively.
When the mold is opened, the skin 12 is set on the inner surface of the lower mold 24, and the core material 14 is set on the inner surface of the upper mold 22. In addition, in the figure, 28
is a removable holding pin that fixes the core material 14 to the upper die 22.

Incidentally, here, a breathable sheet 30 is attached to the core material 14 on the surface thereof that is positioned inside the foam mold 26. This breathable sheet 30 allows gas to flow under pressure similar to that during a foaming operation, but does not substantially allow the foamed material to flow, and at least allows the foamed material to pass through it without oozing out to the extent that it does not pose a problem for the product. A film or sheet having continuous pores or open cells that can be suppressed to a low temperature, such as a nonwoven fabric, a urethane foam, or a synthetic resin film having pores, more specifically, for example, a normal nonwoven fabric, or a foam density of 0.02~ A commercially available slab form of ether-based polyurethane having a density of 0.04 g/cm ³ , an open cell ratio of 85 to 95%, and a thickness of about 1 to 3 mm is preferably used.

In addition, the breathable sheet 30 covers the entire surface of the core material 14 so as to cover the opening forming part 18, the hole 20, etc. extending outward in length (width);
It is formed to have a size that extends to the mating surface of the upper mold 22 and lower mold 24 of the foaming mold 26.

Such a breathable sheet 30 is attached to the core material 14 at the same time as the core material 14 is formed.

That is, such a breathable sheet 30 is used as the core material 1
The core material 14 is formed by injecting and filling a predetermined resin material into the molding cavity of the injection mold forming the core material 14, which is placed along the inner surface of the movable plate. By doing so, the core material 1 is heated by the heat of the injection resin material.
The air permeable sheet 30 is fused and attached at the same time as the forming of the air permeable sheet 4, and thereby the step of adhering the air permeable sheet 30 to the core material 14 can be omitted, and the process can be simplified. This can be achieved effectively.

Then, the core material 14 with the continuous sheet 30 attached thereto is set on the upper mold 22 by the holding pins 28 and the like as described above, but as shown in FIG. With such a set,
The core material 14 includes a breathable sheet 3 on the inner surface of the upper mold 22.
0, and as a result, the holes for the mounting bolts 16 provided in the core material 14, the opening forming part 18, the molded hole 20, etc., and the periphery of the end of the core material 14 are covered. , and will be covered with the breathable sheet 30.

Next, as described above, the foam molding mold 26 in which the skin 12 and the core material 14 have been set is placed in the molding cavity of the lower mold 24 according to the usual method, as shown in FIG. A predetermined foam material 32 such as urethane is injected from an injection device 34,
After closing the upper mold 22 and the lower mold 24, the vulcanization (foaming) operation is performed by placing the upper mold 22 and the lower mold 24 in an oven and heating and maintaining the temperature at, for example, 40 to 60°C, as shown in FIG. will be carried out.

Here, by closing the foaming mold 26, the peripheral edges of the ends of the breathable sheet 30, together with the peripheral edges of the skin 12, are formed between the upper mold 22 and the lower mold 24.
The continuous sheet 3 is sandwiched between
It will be covered by 0. That is, during such a foaming operation, the foam material 32 is transferred to the foam mold 26.
Foaming occurs in the space between the breathable sheet 30 and the outer skin 12 inside the breathable sheet 30.
A predetermined foam layer 36 is formed on one side of the core material 14 via the foam layer 36 .

As described above, the air permeable sheet 30 has various holes (bolt holes, molded holes, opening forming holes) formed in the core material 14 because the foamed material 32 can substantially flow through the elements. ) and core material 1
The foamed material 32 can be effectively prevented from going around to the back side through the gap between the four end edges and the upper mold 22, thereby effectively preventing the occurrence of defects such as burrs in the foamed product. It will be done.

Moreover, in particular, in the case of such a breathable sheet 30, the foamed material 32 has air holes made of continuous pores or bubbles as described above.
During the foaming operation, the foamed material 32 enters the ventilation holes, and the two are fused and integrated, thereby increasing the adhesion strength of the foamed material to the breathable sheet 30 and, by extension, to the core material 14. , can be very advantageously improved.

Furthermore, the ventilation holes of the breathable sheet 30 are as follows:
Since it allows gas to flow, air remaining in the foaming space formed between the breathable sheet 30 and the skin 12 in the closed foaming mold 26 during the foaming operation. The gas generated during the foaming operation can be effectively discharged to the outside of the foaming air through the various holes in the core material 14 and the air-permeable sheet 30 that covers the gap between the edge of the core material 14 and the upper mold 22. As a result, air traps and peeling between the skin 12 and the foam layer 36 (loose skin) occur in the foamed product.
Alternatively, the occurrence of defects such as spaces and voids, or the non-uniformity of foaming due to an increase in the internal pressure of the foaming space, can be extremely effectively prevented.

The foam product obtained by foam molding while exhibiting these characteristics is taken out from the foam mold 26 in the same manner as in the conventional method, as shown in FIG. Since it simply has an extension 38 extending outward from the product outline, the extension 38 is removed by being cut (trimmed) at its base A, and at the same time exists in the part 40 that will become the product opening. Since the skin 12 and the breathable sheet 30 are also removed, there is no need for deburring (finishing) work as in the past, and the structure shown in FIGS.
It can be used as the final product shown in the figure.

Therefore, if such a method is followed, by the flow element function of the foamed material by the breathable sheet 30,
In addition to completely preventing urethane leakage and eliminating the need for wasted man-hours required to remove burrs caused by this, this breathable sheet 30
Due to the gas flow permitting function, residual air and generated gas can be effectively discharged from the foaming space, and the residual air and internal pressure increase in the foaming space can be avoided. The occurrence of defects due to loose skins, voids, etc. can be advantageously prevented, and the quality of the resulting product can be improved and stabilized very effectively.

Further, if such a method is followed, an increase in the internal pressure of the foaming space can be avoided, so the strength of the foaming mold 26 can be lowered, which has the advantage of reducing costs. That's what I'm doing.

Furthermore, in the present embodiment, the adhesive strength of the foam layer 36 to the breathable sheet 30 and, by extension, to the core material 4 is improved by entering the foam material 32 into the air holes of the breathable sheet 30. As can be seen from the drawing, the materials of the foam layer 36 and the breathable sheet 30 are not particularly limited in terms of their adhesive properties.

Further, in the above embodiment, the breathable sheet 3
Since the adhesion to the core material 14 of No. 0 can be performed at the same time as the molding of the core material 14, the number of steps can be effectively reduced, and the occurrence of misalignment of the adhesion position and incomplete adhesion can be avoided. , can be effectively prevented.

Although one embodiment of the present invention has been described in detail above, this is a literal illustration, and the present invention is not to be construed as being limited to such specific example.

For example, in the embodiment described above, the breathable sheet 30 was applied over the entire surface of the core material 14, but it was applied to necessary predetermined areas such as the holes for the mounting bolts 16, the opening forming portions 18, and the forming holes 20. In addition, it may be applied to cover the holes.

In addition, in the above embodiment, the breathable sheet 3
However, for the purpose of the present invention, such a breathable sheet 30 is applied to the side where the foam layer 36 of the core material 14 is not formed. Of course, it is also possible to cover the side surfaces.

When the breathable sheet 30 is applied to the side of the core material 14 on which the foam layer 36 is not formed, the foam layer 36 is formed by a foaming operation.
is directly bonded to the core material 14, so the breathable sheet 3 is bonded directly to the core material 14.
Furthermore, the breathable sheet 30 is made of an elastic porous synthetic resin such as polyurethane foam, and By increasing the thickness, the breathable sheet 30
as a cushion layer between the attachment surfaces for other members attached to the back side of such foam products,
Alternatively, it is also possible to use it as a sealing layer by applying pressure between these two members.

Furthermore, in the embodiment described above, the skin 12 was constituted by a separate member, but instead of this, a so-called skin layer is formed on the surface of the foam layer 36 at the same time in the known foam molding process. A skinless method can also be adopted.

Although not listed in detail, the present invention can be implemented in various modifications, modifications, improvements, etc. based on the knowledge of those skilled in the art, and such embodiments do not exceed the spirit of the present invention. It goes without saying that all of these are included within the scope of the present invention as long as they do not deviate from them.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a safety pad which is an example of a foamed product with a core material manufactured by the method of the present invention, and FIG. 2 is a cross-sectional view taken from FIG. 1. Further, FIGS. 3 to 6 are cross-sectional explanatory views showing the manufacturing process of such a safety pad according to the present invention, respectively. 10: Safety pad, 12: Outer skin, 14: Core material, 22: Upper mold, 24: Lower mold, 26: Foaming mold, 30: Breathable sheet, 32: Foaming material, 3
6: Foam.

Claims (1)

[Claims] 1. A film is applied to a core material having a predetermined shape so as to cover a predetermined portion of the core material, and the core material is foamed while being placed in a foam mold. When manufacturing a foamed product with a core material in which a foam layer is integrally formed on one side of the core material by foaming the material, as the coating, gas is allowed to flow, but the foam material is substantially Using an air-permeable sheet having continuous holes that do not allow air to flow through the core material, the air-permeable sheet is placed at a predetermined position in a mold for forming the core material, and filled with a predetermined resin material to form the core material. At the same time as the core material is molded, the air permeable sheet is applied by fusion to the side of the core material on which the foam layer is formed or on the side where the foam layer is not formed. A method for manufacturing a foamed product with a core material, characterized in that the core material to which the breathable sheet is adhered is placed in the foam mold, and the foam layer is foam-molded.