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US 7,172,721 B2Granted
Thermoplastic molding process
AssigneeJ.T. Labs, Ltd.
InventorTit Shing Wong
Life of this patent
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Abstract
The invention provides a novel thermoplastic molding process useful in the manufacture of hollow, deformable thermoplastic articles such as hollow doll heads. In the process of the instant invention, a parison is formed at a first injection station and is transferred to a blow mold station. At the blow mold station, the parison is transformed into a hollow, deformable thermoplastic article through application of a vacuum and gas injection. Articles made by the process of the instant invention have a highly realistic appearance and texture.
Claims40
A process for making a deformable, hollow thermoplastic doll head, comprising:
- (a) providing an injection moldable flexible thermoplastic elastomer;
- (b) providing a first mold, the mold comprising exterior mold front and rear sections and an interior core which extends vertically through the first mold, the first mold comprising a parison injection station, wherein the exterior sections of the first mold are spaced apart from the interior core to define a first mold cavity in the shape of a a complete doll head below a latitudinal plane intersecting the head at a position above the eyes and below the crown of the head;
- (c) assembling the exterior mold sections of the first mold thereby forming a planar junction between the exterior mold parts;
- (d) during an injection molding process, injecting the elastomer into the first mold cavity to form a parison;
- (e) opening the exterior mold parts of the first mold and transferring the rear section of the first mold and the parison to a blow station;
- (f) providing a second mold at the blow station, the second mold comprising an exterior mold front section, the rear section of the first mold, and an interior core, wherein the exterior mold front section of the second mold and the rear section of the first mold exterior sections are oriented latitudinally relative to one another and wherein the exterior sections of the second mold are spaced apart from the interior core of the second mold to define a cavity in the shape of the entirety of the hollow doll head;
- (g) during a blow molding process drawing a vacuum on, and injecting compressed gas into, the second mold, thereby dispersing the parison relatively evenly, and with a substantially uniform thickness, against the second mold cavity interior surface to form the hollow doll head, the hollow doll head having an opening for removing the interior core;
- (h) cooling the dispersed parison, thereby causing it to set and form the hollow doll head having facial features determined by injection molding and a crown determined by blow molding;
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- (i) separating the second mold interior core from the hollow doll head, wherein (I) the second mold cavity vacuum pressure ranges from about −7 psig to about −14.5 psig, the pressure of the compressed gas injected into the second mold ranges from about 80 psig to about 1,000 psig, the parison injection station temperature is from about 150° C. to less than about 300° C., the temperature of the compressed gas injected into the second mold ranges from about 30° C. to about 40° C., a vacuum is drawn upon the first mold cavity for about three to about ten seconds prior to the end of the elastomer injection period, the elastomer is injected into the first mold cavity over a period of from about 0.2 to about 6 seconds and the cooled and dispersed parison sets within the second mold in about 5 seconds to about 90 seconds;
- and
- (ii) the doll head has a hair line which forms a substantially continuous circle extending around the top of the doll head, and the first mold cavity is in the shape of a portion of the hollow doll head below the hair line, the rear section of the first mold defining facial features of the hollow doll head, the facial features of the doll head formed during the injection molding process remaining unchanged by the blow molding process.
9 more elements
A process for making a deformable, hollow thermoplastic doll head, comprising:
- (a) providing an injection moldable flexible thermoplastic elastomer;
- (b) providing a primary mold including an exterior first mold section and an exterior second mold section and further including an interior core extending vertically through the primary mold, the exterior sections of the primary mold being spaced from the interior core at an injection station to define a first mold cavity in the shape of a a complete doll head below a latitudinal plane intersecting the head at a position above the eyes and below the crown of the head, the first mold section of the primary mold being formed with details of a face of the doll head;
- (c) assembling the exterior mold sections of the primary mold so as to form a planar junction between the exterior mold sections;
- (d) during an injection molding process, injecting the elastomer into the first mold cavity of the primary mold at the injection station to form a parison having facial features formed by the first mold section of the primary mold;
- (e) opening the exterior mold sections of the primary mold and transferring the first mold section together with the parison to a blow station;
- (f) providing a secondary mold at the blow station, the secondary mold comprising an exterior third mold section, the first mold section, and the interior core, wherein the third mold section and the first mold section are spaced apart from the interior core to define a second mold cavity in the shape of the entirety of the doll head;
- (g) drawing a vacuum on, and injecting compressed gas into, the secondary mold, at the blow station, thereby dispersing the parison relatively evenly during a blow molding process, and with a substantially uniform thickness, against an interior surface of the second mold cavity to form a molded hollow doll head, the hollow doll head having an opening for removing the interior core;
- (h) cooling the dispersed parison, thereby causing it to set in the form of the hollow doll head having facial features determined by injection molding and a crown determined by blow molding;
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- (i) separating the interior core from the hollow doll head;
- and
- (j) removing the hollow doll head from the first mold section, the facial features of the doll head having been formed against the first mold section during the injecting the elastomer into the first mold cavity, the facial features of the doll head remaining unchanged by the blow molding process.
9 more elements
Dependencies are inferred from the claim text.