Manufacturing method of integrated foam-molded product
To obtain an integrated foam-molded product whose manufacturing cost is reduced and which makes an effective use of a property of an integration target. Foaming heat generated at the time of the foaming of a polyurethane foam raw material, whose influence has been conventionally prevented by contriving a special measure, is positively used. The integration target is influenced by foaming heat generated at the time of the foaming of the polyurethane foam raw material in a mold, to thermally deform into a desired shape along a mold shape. Consequently, it is possible to mold the integration target into an arbitrary shape in a step of integrating the integration target with a polyurethane foam layer in the mold by integrated foaming, and therefore, there is no need to work the integration target to a state closer to a final shape in a step before it is disposed in the mold, which can simplify manufacturing steps and reduce manufacturing cost.
1. A manufacturing method of an integrated foam-molded product which injects a polyurethane foam raw material into a mold to foam the polyurethane foam raw material and integrates an integration target disposed in the mold with a polyurethane foam layer, the method comprising:
thermally deforming the integration target by foaming heat generated at the time of the foaming of the polyurethane foam raw material to mold the integration target into a predetermined shape, and obtaining an integrated foam-molded product in which the integration target is integrated with the polyurethane foam layer,
wherein the integration target is made of a three-dimensional structure having air permeability and comprising a three-dimensional knitted fabric having a pair of ground knitted fabrics and connecting yarns knitted back and forth between the ground knitted fabrics, wherein the integration target is molded into the predetermined shape by the thermal deformation along the inner surface of the mold while a pressure of gas generated at the time of the foaming of the polyurethane foam raw material is used for shape retention of the three-dimensional structure,
integrating the three-dimensional structure with the polyurethane foam layer in the mold while suppressing an entrance of the polyurethane foam raw material into gaps between the connecting yarns through the ground knitted fabric by the pressure of the gas, and
joining a skin layer to at least part of the three-dimensional knitted fabric to provide the integration target as a skin layer joined three-dimensional structure,
wherein as the three-dimensional knitted fabric, a gray fabric not having undergone a heat setting process is used, and
wherein, when the skin layer is joined to the gray fabric of the three-dimensional knitted fabric, the skin layer is joined so as to have a slack relatively to the gray fabric between joined portions.
2. The manufacturing method of the integrated foam-molded product according to claim 1 , wherein the three-dimensional structure forming the skin layer-joined three-dimensional structure at least partly has a sparse portion that is formed as a sparser structure than a peripheral portion or formed as a void, and the polyurethane foam layer is fixed to the skin layer via the sparse portion.
3. The manufacturing method of the integrated foam-molded product according to claim 2 , wherein the skin layer and the three-dimensional structure forming the skin layer-joined three-dimensional structure are joined to each other by sewing or melt adhesion, or via a hook-and-loop fastener.
4. The manufacturing method of the integrated foam-molded product according to claim 1 , wherein part of the ground knitted fabric included in the three-dimensional knitted fabric is disposed in the polyurethane foam layer.
5. The manufacturing method of the integrated foam-molded product according to claim 1 , the method being applied to manufacturing of an integrated foam-molded product forming a seat cushion, a seat back, a headrest, or an armrest of a vehicle seat.