Method for manufacturing shoe body with foamed dual-layer midsole formed by supercritical foaming injection molding and shoe body with foamed dual-layer midsole formed by supercritical foaming injection molding

1 . A method for manufacturing a shoe body with a foamed dual-layer midsole formed by supercritical foaming injection molding, wherein the shoe body comprises the foamed dual-layer midsole and an upper bonded to each other; the method comprising the steps of:

step S 1 : providing a first midsole module, wherein the first midsole module comprises an upper mold and a first midsole mold; the upper mold comprises an upper mold cavity, wherein the upper, sleeved onto a shoe last, is pre-disposed in the upper mold cavity; the first midsole mold comprises a first midsole mold cavity and a plurality of first injection runners, wherein the first injection runners are connected to the first midsole mold cavity;

step S 2 : sealing the first midsole mold to the upper mold to form a first midsole mold chamber defined by the upper mold cavity and the first midsole mold cavity, wherein the first injection runners are in communication with the first midsole mold chamber;

step S 3 : injecting a first foaming material comprising a first supercritical fluid into the first midsole mold chamber through the first injection runners, so as to foam and mold the first foaming material to form a first foamed midsole layer, and to integrally bond the first foamed midsole layer to the upper;

step S 4 : opening the upper mold and the first midsole mold, with the first foamed midsole layer and the upper remaining on the upper mold; a first bottom surface of the first foamed midsole layer comprises a plurality of foamed columns, wherein the foamed columns correspond to a plurality of positions of the first injection runners and are exposed from the upper mold cavity;

step S 5 : trimming the first bottom surface of the first foamed midsole layer to remove the foamed columns on the first bottom surface;

step S 6 : providing a second midsole module comprising a second midsole mold, wherein the second midsole mold comprises a second midsole mold cavity and a plurality of second injection runners, and the second injection runners are connected to the second midsole mold cavity;

step S 7 : sealing the second midsole mold to the upper mold, with the first foamed midsole layer disposed on the upper mold, to form a second midsole mold chamber between the first foamed midsole layer and the second midsole mold cavity, wherein the second injection runners are in communication with the second midsole mold chamber; and

step S 8 : injecting a second foaming material comprising a second supercritical fluid into the second midsole mold chamber through the second injection runners, so as to foam and mold the second foaming material to form a second foamed midsole layer, and to integrally bond the second foamed midsole layer to the first bottom surface of the first foamed midsole layer; the first foamed midsole layer and the second foamed midsole layer together form the foamed dual-layer midsole, thereby obtaining the shoe body.

2 . The method as claimed in claim 1 , wherein the upper mold comprises two clamping blocks disposed on the upper mold; when the upper, sleeved onto the shoe last, is disposed on the upper mold, the two clamping blocks are relatively movable and contact two sides of a bottom surface of the upper; the upper mold cavity is located between the two clamping blocks.

3 . The method as claimed in claim 2 , wherein the first midsole module comprises a first mold cover comprising a plurality of first feeding holes; sealing the first midsole mold to the upper mold comprises: first disposing the first midsole mold on the two clamping blocks, then placing the first mold cover over a periphery of the first midsole mold and a periphery of the two clamping blocks, and finally sealing the first mold cover to the upper mold; the first feeding holes are in communication with the first injection runners of the first midsole mold.

4 . The method as claimed in claim 1 , wherein when the first foaming material foams and molds to form the first foamed midsole layer in the first midsole mold chamber, the first foamed midsole layer is bonded to the upper by thermal fusion, without an adhesive layer being provided between the first foamed midsole layer and the upper.

5 . The method as claimed in claim 2 , wherein the second midsole module comprises a second mold cover comprising a plurality of second feeding holes; sealing the second midsole mold to the upper mold comprises: first disposing the second midsole mold on the two clamping blocks, then placing the second mold cover over a periphery of the second midsole mold and a periphery of the two clamping blocks, and finally sealing the second mold cover to the upper mold; the second feeding holes are in communication with the second injection runners of the second midsole mold.

6 . The method as claimed in claim 1 , wherein when the second foaming material foams and molds to form the second foamed midsole layer in the second midsole mold chamber, the second foamed midsole layer is bonded to the first bottom surface of the first foamed midsole layer by thermal fusion, without an adhesive layer being provided between the first foamed midsole layer and the second foamed midsole layer.

7 . The method as claimed in claim 1 , wherein an outsole is pre-disposed in the second midsole mold cavity of the second midsole mold; when the second midsole mold is sealed to the upper mold, the outsole faces the first bottom surface of the first foamed midsole layer; the second midsole mold chamber is located between the outsole and the first foamed midsole layer.

8 . The method as claimed in claim 7 , wherein a plurality of protruding tubes are disposed within the second midsole mold cavity, and protrude at a plurality of positions corresponding to the second injection runners; a plurality of through holes are disposed on the outsole and are respectively sleeved onto the protruding tubes; when the second foamed midsole layer is formed in the second midsole mold chamber, the second foamed midsole layer is formed with a plurality of protrusions, which are respectively located within the through holes of the outsole.

9 . The method as claimed in claim 7 , wherein an insert is pre-disposed between the second midsole mold and the upper mold before sealing the second midsole mold to the upper mold; the insert is fixed in the second midsole mold chamber, and the second foaming material is injected into the second midsole mold chamber to cover the insert.

10 . The method as claimed in claim 9 , wherein the insert is a carbon plate or a thermoplastic support plate; the thermoplastic support plate is selected from a group consisting of thermoplastic polyurethane elastomer (TPU), polyether block amide copolymer (PEBA), and a combination thereof.

11 . The method as claimed in claim 1 , wherein the first foaming material is selected from a group consisting of ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), styrene-ethylene/butylene-styrene copolymer (SEBS), thermoplastic polyurethane elastomer (TPU), thermoplastic polyester elastomer (TPEE), polyether block amide copolymer (PEBA), and a combination thereof; an injection screw temperature of the first foaming material ranges from 100° C. to 300° C.

12 . The method as claimed in claim 1 , wherein setting a first gas pressure value within the first midsole mold chamber before injecting the first foaming material into the first midsole mold chamber, with the first gas pressure value ranges from 0 to 40 bar; the first supercritical fluid is nitrogen or carbon dioxide.

13 . The method as claimed in claim 1 , wherein the second foaming material is selected from a group consisting of ethylene-vinyl acetate copolymer (EVA), polyolefin elastomer (POE), styrene-ethylene/butylene-styrene copolymer (SEBS), thermoplastic polyurethane elastomer (TPU), thermoplastic polyester elastomer (TPEE), polyether block amide copolymer (PEBA), and a combination thereof; an injection screw temperature of the second foaming material ranges from 100° C. to 300° C.

14 . The method as claimed in claim 1 , wherein setting a second gas pressure value within the second midsole mold chamber before injecting the second foaming material into the second midsole mold chamber, with the second gas pressure value ranges from 0 to 40 bar;

the second supercritical fluid is nitrogen or carbon dioxide.