JPH0375008B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing a foamed resin molded article having a skin material such as cloth or leather. The present invention is used, for example, to manufacture interior parts such as headrests, armrests, and seats for automobiles. [Prior Art] Conventionally, in order to manufacture headrests used for automobile seats, for example, a foam molded product of a predetermined shape is molded from foamed urethane resin, and then a separately formed bag-shaped skin material is covered. It is common to manufacture However, in the above-mentioned manufacturing method, since the molded body and the skin material are separate bodies, there are cases where a gap is created between the two or wrinkles are generated in the skin material, which impairs the appearance. Further, even after the cover is covered, troublesome processing such as sewing is required, which requires a large number of man-hours. Furthermore, depending on the shape of the molded product, it may be impossible to cover it with a skin material, and therefore it is not possible to freely select a design shape. Furthermore, when the skin material is applied, the convex parts of the molded body may be compressed and the shape may change, so the molded body must be made harder than necessary, which may result in poor feeling during use. Ta. In order to prevent such problems, a manufacturing method in which a skin material is placed in a mold and the molded product is integrally foamed has been studied in recent years. However, if the skin material is cloth, the gas during molding will pass through the skin material, making it difficult for the foaming pressure to be transmitted to the skin material, making it difficult to obtain a product with the desired shape, and the foamed resin will penetrate to the surface of the skin material. and express it. Therefore, in Japanese Patent Application No. 61-179252 (unknown), the applicant sewed a sheet-like material in which a gas-shielding layer and a cloth-like material were integrally joined as a skin material, We have proposed a manufacturing method that applies pressure to the skin material to give it a predetermined shape, and also prevents the skin material from being impregnated with foamed resin. [Problems to be solved by the invention] However, in such a manufacturing method, when the pressure of foaming is transmitted to the skin material, a large tensile force acts on the skin material, and the needle hole widens in the sewing area. A gap is created between the thread and the sheet material.
Therefore, the foamed resin oozes out from the gap onto the surface of the skin material as shown in FIG. 7, resulting in a loss of quality and failure. In order to prevent this kind of problem, there is a method of sealing the seams by placing tape on the sewn part after sewing, but it is not easy to ensure that the tape follows the sewn part. In some cases, resin oozed from the seams due to poor sealing. The present invention has been made in view of the above circumstances, and is intended to prevent gaps from forming between the sheet-like material and the threads when a tensile force is applied to the skin material during molding. The present invention provides a method for manufacturing a foamed resin molded article having a skin material that can prevent oozing. [Means for Solving the Problems] The method of manufacturing a foamed resin molded article having a skin material according to the present invention comprises a sheet-like molded article comprising a skin material and a fluid shielding layer integrally joined to the back side of the skin material. A cutting process in which the material is cut into a predetermined unfolded shape, a sewing process in which a plurality of cut sheet materials are sewn together using inflatable thread to form a bag-shaped skin material, and a sewn part sewn in the sewing process. an expansion step in which the expandable thread is expanded at least in the radial direction, and a skin material is placed in a mold while the expandable thread is maintained in an expanded state, and foamed resin is injected from an opening in the skin material to expand the foamed resin. a molding process of pressing the skin material against the mold surface of the mold using foaming pressure to form a molded body that fills the inside of the skin material; a demolding process of opening the mold and taking out the molded body covered with the skin material; It is characterized by being more. As the skin material, materials similar to those used for conventional skin materials, such as woven fabric, non-woven fabric, leather, and resin, can be used. The fluid shielding layer shields gas or foamed resin, and may have the function of pressing the skin against the mold surface in response to the foaming pressure during molding. The gas permeability can be variously selected depending on the foaming pressure. This fluid shielding layer is made of a soft material, such as a resin film or a foam made of closed cells. Note that it is desirable to select a fluid shielding layer that has good bonding properties with the foamed resin. For example, when the foamed resin is a urethane resin, the fluid shielding layer is preferably formed from a polyurethane film. The sheet-like material is made by joining the skin body and the fluid shielding layer. The skin and the fluid shielding layer can be bonded using a laminating method such as adhesive treatment, welding treatment, or pressure bonding treatment. It is desirable that a thick soft foam layer be disposed between the skin and the fluid shielding layer or on the surface of the fluid shielding layer. In this way, it will be possible to maintain its softness and have excellent shape retention, and the skin material will have excellent shape retention performance in the mold, so defects caused by misalignment of the skin material during molding can be avoided. It can be prevented. Note that it is advantageous to use a foam made of closed cells for the fluid shielding layer because it provides excellent shape-retaining performance without the need for a soft foam layer. In the cutting process, the sheet material is cut into the developed shape of the desired product. The sewing process is a process in which a plurality of sheet materials cut in the cutting process are sewn to form a bag-shaped skin material. One feature of the present invention is that an expandable thread is used as the thread used in this sewing process. Expandable thread refers to a thread whose diameter at least expands after sewing. For example, threads that contain a water-absorbing resin and expand by absorbing water can be used. Such water-absorbing resins include acrylate thread polymers, vinyl alcohol-acrylate copolymers, etc., and these water-absorbing resins can be coated on conventional threads, or A thread that expands when it absorbs water can be formed by twisting the fibers or other methods. It is also possible to use threads that contain a thermally expandable material and expand due to heat. This thermally expandable material has
For example, a thermoplastic resin mixed with a blowing agent can be used. Such materials can then be used alone or in combination with conventional yarns as described above to form thermally expandable yarns. Furthermore, a thread consisting of a base and a cilia portion formed on the surface of the base can also be used. If such a thread is used, during sewing, the ciliary part is inserted into the needle hole and sewn in a state parallel to the base, and the cilia part stands up after sewing, so that the diameter of the thread is expanded. Such yarns include spun yarns, curling yarns, and the like. The expansion step is a step of expanding the expandable threads of the sewn portion by means corresponding to the expansion means of each expandable thread. For example, when the expandable yarn contains a water-absorbing resin, the expandable yarn can be made to absorb water by keeping the skin material under humid conditions for a certain period of time or by directly contacting it with water. In addition, when the material contains a thermally expandable material, it is heated to a temperature higher than the temperature at which the material expands thermally. Spun yarn, curling yarn, etc. automatically expand after sewing. In addition, when using spun yarn, curling yarn, etc., it is also preferable to use one containing a thermoplastic resin that melts when heated in the cilia portion. When the thermoplastic resin is melted by heating after the sewing process, the thermoplastic resin flows and fills the gap between the skin material and the thread. Gaps are therefore further prevented from forming when tensile forces are applied. Furthermore, the expandable thread and the surrounding sheet-like material are often welded together at the seams, making it possible to further prevent oozing of the foamed resin. In the molding process, the skin material sewn with expandable thread is placed in a mold, and foamed resin is injected through the opening of the skin material. Here, as the foamed resin, conventionally used resins such as polyurethane, polystyrene, polyvinyl chloride, polyethylene, and polypropylene can be used as they are.
In addition, the foaming method can be the same as conventional methods, such as adding a foaming agent such as chlorofluorocarbon, methylene chloride, or butane, or using reaction product gas such as carbon dioxide produced by the reaction of water and isocyanate. Can be adopted. Then, the foamed resin is foamed by means such as heating to form a molded body filling the inside of the skin material. The most important feature of the present invention is that this molding step is carried out while the expandable yarn is maintained in an expanded state. When the expandable thread is expanded, the sheet material surrounding the expandable thread and the surface of the expandable thread are in pressure contact at the seam portion, and the expansion of the expandable thread is regulated by the peripheral wall of the needle hole. . Further, the needle hole is expanded by the expansion of the expandable thread, so that the inside of the needle hole is filled with the expandable thread. Therefore, when a tensile force is applied to the sheet-like material due to foaming of the foamed resin, the expandable thread expands further in the radial direction, or the needle hole is already expanded and is prevented from expanding. It is presumed that this prevents a gap from forming between the sheet-like material and the expandable thread, and prevents the foamed resin from seeping out from the seams. Then, the product is taken out in the demolding step, and one cycle of the manufacturing method of the present invention is completed. [Operations and Effects of the Invention] In the manufacturing method of the present invention, the skin material is sewn with expandable threads. Then, in the molding process, the foamed resin is foamed while the expandable thread is maintained in an expanded state. During the molding process, the skin material expands due to the pressure of foaming, and a tensile force acts on the seam area, causing the needle hole to expand. However, at this time, the expandable thread, whose expansion was regulated by the peripheral wall of the needle hole, expands further and blocks the expanded needle hole, or because the needle hole has already expanded, it does not expand any further and foams. It is presumed that the resin is prevented from seeping out from the seams. That is, according to the manufacturing method of the present invention, it is possible to reliably prevent the foamed resin from seeping out from the seam portion of the skin material during molding, resulting in defects, and it is possible to reduce the defect rate. [Example] The following is a concrete explanation using Examples. In this example, the manufacturing method of the present invention is applied to the manufacturing of a headrest placed above the seat of an automobile. (1) Example 1 (Cutting process) As shown in Fig. 1, a 3 mm thick urethane soft foam (slab foam) 11 was adhered to the back side of a 2 mm thick woven fabric 10, and the soft foam body 11
A sheet material 1 was prepared, on which a polyurethane film 12 having a thickness of 30 μm was laminated as a gas shielding layer by heat fusion. This sheet-like material 1 was then cut into the developed shape of the intended head list to obtain a plurality of partial sheet-like materials. (Sewing process) Water-absorbing resin (“NY1010” manufactured by Sumitomo Chemical Co., Ltd.)
300 parts by weight and 100 parts by weight of EPDM ("Espren 512" manufactured by Sumitomo Chemical Co., Ltd.) were kneaded with a roll,
A resin liquid having a solid content of 25% by weight was prepared by dissolving it in toluene. This resin liquid was applied to a 600 denier polyester thread in an amount of 0.08 g/m to form a 1350 denier expandable thread 2. Next, as shown in Figure 2, align the partial sheet-like material with the center side, leaving the bottom part of the head rest, and sew it with a sewing machine needle (#18) using the expandable thread 2 at a pitch of 4 mm. The skin material 1' was then sewn into a bag shape in the desired headrest shape. (Expansion step) The skin material 1' was left in an atmosphere of 80° C. and 90% humidity for 1 hour to allow the expandable threads 2 to absorb water. In addition, under this condition, the weight of the expandable yarn 2 becomes 1.5 times,
It is known that the linear expansion in the radial direction is approximately 1.2 times. (Molding process) While maintaining the expanded state of the expandable thread 2, the third
As shown in the figure, the inserts 2 fixed to the ends of the two stays 3 were inserted into the skin material 1' from the open bottom surface. And as shown in Figure 4,
The mold was placed in the mold 6 and the mold was clamped so that the injection port 7 of the mold 6 and the opening of the skin material communicated with each other. Then, from the injection port 7, a polyether polyol ("Sumifuen 3063", Sumitomo Bayer Urethane Co., Ltd.)
) 80 parts by weight, polymer polyol (POP31
-28'', manufactured by Mitsui Toatsu Chemical Co., Ltd.) 20 parts by weight, 4.0 parts by weight of distilled water as a blowing agent, 1.5 parts by weight of triethylenediamine (``DABCO33LV'', manufactured by Nippon Nyukazai Co., Ltd.), and silicone-based Surfactant (SPX-
274C, manufactured by Toray Silicone Co., Ltd.) and toluene diisocyanate (TDI -80'', manufactured by Sumitomo Bayer Urethane Co., Ltd.) 3
curing agent components mixed at a weight ratio of 65
A foamed polyurethane resin material mixture mixed in a ratio of 35% was injected. In addition, since the skin material 1' had a slab foam layer, it was placed reliably along the shape of the mold surface within the mold, and had excellent shape retention performance. The mold was then heated to about 40°C and held for 6 minutes. As a result, the foamed polyurethane resin material mixture expanded to approximately 20 times its volume and was cured. At this time, since the urethane film 12 does not allow gas to pass through, the pressure of the foaming of the foamed polyurethane resin causes the skin material 1'
was pressed against the mold surface, and in that state, the foamed resin filled the inside of the skin material 1' and hardened, so that the foamed resin did not ooze out from the seams. (Mold Removal Step) After the polyurethane foam resin had hardened, the mold was opened and a head rest consisting of a molded body covered with a skin material was taken out. In the obtained headrest, as shown in a cross section of the principal part in FIG. 5, the molded body 8 was integrally joined to the urethane film 12, and the inside of the skin material 1' was densely filled. There were no wrinkles or exudation of the foamed polyurethane resin on the surface of the skin material 1', and the head rest was in a good shape along the mold surface. In addition, in the molding method using foamed resin, the heavier the weight of the molded article in the same volume, the higher the foaming pressure, and therefore the resin leakage from the sewn portion is more likely to occur. Therefore, the weight level of the molded body was set at 230
A headrest was produced in the same manner as above using 5 stages of weighing between 310g and 310g. As a result, as shown in the table, no resin leakage occurred from the seams in any case. (2) Example 2 In this example, "Celmic CAP500" (Sankyo Kasei) was added as a foaming agent to the 600 denier polyester thread used in Example 1 as the thread used in the sewing process.
Evatate D2021, an EVA (ethylene vinyl acetate) containing 1.0% by weight of EVA (manufactured by Sumitomo Chemical Co., Ltd.)
A yarn coated with 0.085 g/m of Co., Ltd.) was used. The procedure was the same as in Example 1 except that in the expansion step, the skin material was heated to 140° C. to foam the EVA, and the thread was expanded, followed by a molding step. As shown in the table, no exudation of the foamed resin from the seams was observed in the headrest obtained in this example. (3) Example 3 This example is the same as Example 1 except that the forming process was performed using spun yarn (100% polyester yarn (#8) manufactured by Gunze Co., Ltd.) as the thread used in the sewing process. The same is true. As shown in FIG. 6, this spun yarn 9 consists of a base portion 90 and a cilia portion 91. Cilia part 9
1 is pressed against the peripheral wall of the needle hole during sewing, and the base 90
It deforms elastically along the needle hole, and after sewing, it apparently expands to press against the wall surrounding the needle hole. As shown in the table, no exudation of the foamed resin from the seams was observed in the headrest obtained in this example. (4) Comparative Example This is the same as Example 1 except that the forming process was performed using a conventionally used sewing thread (polyester thread #8) as the thread used in the sewing process. As shown in the table, in the headrest obtained in this comparative example, resin leaked from several places in the sewn parts when the weight was 250g, and as the weight increased, the number of resin leakage areas increased, and when the weight was 270g or more, resin leaked from several places. In some cases, resin oozed out all around the sewing area.

[Table] ○…No leakage △…Leakage occurs partially ×…Leakage occurs around the entire circumference

[Brief explanation of drawings]

1 to 4 relate to an embodiment of the manufacturing method of the present invention, in which FIG. 1 is a sectional view of a sheet material, FIG. Fig. 4 is a perspective view showing the arrangement of the skin material and insert before molding, with a partial cross section; Fig. 4 is a perspective view showing the arrangement of the skin material in the mold; Fig. 5 is a main part of the obtained headrest. FIG. FIG. 6 is a front view of the spun yarn used in the example. FIG. 7 is a sectional view of a main part of a molded article showing resin leakage when molded using a sewn product obtained by a conventional sewing method. 1... Sheet material, 1'... Skin material, 2...
Expandable thread, 3... Stay, 4... Insert, 6
...Mold, 7...Injection port, 8...Molded body, 9...
...Spun thread, 10...Woven fabric, 11...Soft foam, 12...Urethane film, 90...Base,
91...Cilia part.

Claims (1)

[Claims] 1. A cutting step of cutting a sheet-like material consisting of a skin body and a fluid shielding layer integrally joined to the back side of the skin body into a predetermined developed shape, and a plurality of the cut sheets. a sewing process in which a bag-shaped skin material is formed by sewing a shaped material using an inflatable thread; an expansion process in which the inflatable thread in the sewn portion sewn in the sewing process is inflated at least in the radial direction; While maintaining the expanded state of the expandable thread, the skin material is placed in a mold, foamed resin is injected through the opening of the skin material, and the foaming pressure of the foamed resin causes the skin material to be molded into the mold. A molding step of molding a molded body filling the interior of the skin material while pressing against a surface, and a demolding step of opening the mold and removing the molded body covered with the skin material. A method for manufacturing a foamed resin molded article having a skin material that 2 The expandable thread contains a water-absorbing resin, and the expansion step is carried out by making the expandable thread absorb water.
A method for producing a foamed resin molded article having a skin material as described in 2. 3. The expandable yarn contains a thermally expandable material, and the expansion step is performed by heating the expandable yarn.
A method for producing a foamed resin molded article having a skin material as described in 2. 4. Manufacture of a foamed resin molded article having a skin material according to claim 1, wherein the expandable thread is a thread consisting of a base and a cilia, and the expansion step is carried out by raising the cilia after the sewing step. Method.