TH33543B - Methods for manufacturing molded foam products. - Google Patents

Abstract

DC60 (12/11/51) An improved method for the production of cast foam products will be prepared. This method includes a procedure of packing resin containing a foaming agent into the mold cavity by internal injection, from the time point before the completion of mold clamping to the time point after the completion of mold clamping. Allowing the packed resin to form a surface layer over the resin surface, the movable mold is then retracted to define a cavity gap between the movable and stationary molds as predetermined. This allows the foaming agent present in the uncured resin to induce foaming, and the cooling of the packed resin in the mold cavity forms a cast foam product with a dense surface layer and a foamed interior. The mold is precisely fitted at a point in time after the clamping is complete. This allows the resin, which has been packed into the mold cavity, to form a surface layer over the resin. Subsequently, the movable mold is retracted to define the cavity space between the movable and stationary molds as predetermined. This allows the foaming agent present in the uncured resin to form foam, and the dissipation of this foamed resin in the mold cavity creates a molded foam product with a dense surface layer and a foamed interior.

Claims (6)

1. The method of producing cast foam products involves several steps. The resin, containing a foaming agent, is injected into the mold cavity within a time frame from a point before the mold clamping is complete to a point after the clamping is complete. This allows the injected resin to form a superficial layer over the resin surface. A movable mold is then retracted to establish a predetermined cavity gap between the movable and stationary molds. This allows the foaming agent present in the uncured portion of the resin to induce foam formation. Cooling of the injected resin in the mold cavity then molds the foam product, resulting in a dense superficial layer on the surface and a foamy interior. 2. The method under claim 1 in which the amount of resin to be packed into the form cavity at a point in time prior to the completion of form clamping is 50 percent to 80 percent of the total amount of resin to be packed. 3. The method under either claim 1 or 2 in which the packing of this resin at a point in time prior to the completion of this form clamping begins within a period from a time point five seconds prior to the completion of this form clamping to the time point at which this form clamping is completed. 4. Any of the methods under claims 1 through 3 shall inject this resin into the mold cavity at an injection rate of 5 to 20 centimeters per second. 5. Any one of the methods under claims 1 through 4 in which the time from the start of resin filling into the mold cavity until the foaming agent present within the resin-filled cavity begins to foam is 3 to 10 seconds. 6. Any one of the methods under claims 1 through 5 shall adjust the form clamping pressure during the resin filling phase to be within the range of 20 kg/cm² and 100 kg/cm², while adjusting the form clamping pressure during the surface formation phase to be within the range of 20 kg/cm² and 80 kg/cm², resulting in a form clamping pressure during the resin filling phase that is equal to or significantly higher than the form clamping pressure during the surface formation phase.