US3907952A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Injection molding technique
Assignee: Dow Chemical Co
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Filing: 1973-03-05
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Granted: 1975-09-23
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Expires: 1993-03-05
Abstract
Abstract A method of injection molding wherein one mold element is rotated in the critical period after the mold cavity is filled, and to a degree whereby a plastic article of greatly enhanced physical properties is realized whereby the article permanently accepts molecular orientation substantially through its entire thickness. For example, both fibrous filled plastic articles and nonfilled articles are produced exhibiting improved properties oftentimes 50 to 1,000 fold greater than articles produced without rotation, or articles where rotation is caused to occur only accompanying the mold filling cycle.
Inventors
- 👤 Kenneth J Cleereman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 17:36
CPC Classifications
B; B29; B29C; B29C45/00; B29C45/17; B29C45/46; B29C45/56; B29C45/5605
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
158 words
A METHOD FOR INJECTION MOLDING A THERMOPLASTIC ARTICLE HAVING GENERAL ROTATIONARY SYMMETRY TO IMPART USEFUL MOLECULAR ORIENTATION TO THE THERMOPLASTIC OF SAID ARTICLE, SAID METHOD COMPRISING INJECTING A HEAT PLASTIFIED MELT OF MOLECULARLY ORIENTATABLE, THERMOPLASTIC MATERIAL INTO A CLOSED MOLD WITH A CAVITY WHICH DEFINES SAID ARTICLE WHILE SIMULTANEOUSLY ROTATING AT LEAST ONE ELEMENT OF SAID MOLD, SAID INJECTION STEP BEING UNDER CONDITIONS TO INDUCE PERMANENT GENERALLY PREFERRED HELICOIDAL MOLECULAR ORIENTATION, SUBSTANTIALLY THROUGH THE WALL OF THE ARTICLE, THEREAFTER, PROVIDING SUFFICIENT TORQUE TO CONTINUE ROTATABLE MOVEMENT OF AT LEAST ONE ELEMENT COMPRISING SAID MOLD IN THE PERIOD AFTER SAID CAVITY HAS FILLED, SAID ROTATIONAL STEP IMPARTING A STRAIN ON SAID ARTICLE AS IT SOLIDIF ES SUBSTANTIALLY THROUGH THE THICKNESS THEREOF, TO THE EXTENT SAID ARTICLE PERMANENTLY ACCEPTS MOLECULAR ORIENTATION SUSTANTIALLY THROUGH ITS ENTIRE THICKNESS, THE DIRECTION OF THE ORIENTATION VARYING THROUGH THE THICKNESS OF THE ARTICLE, AND BEING ESSENTIALLY OF PREFFERED HOOP DIRECTION IN AN INNER LAYER THEREOF.
Claim 2
Independent Claim
158 words
A METHOD FOR INJECTION MOLDING A THERMOPLASTIC ARTICLE HAVING GENERAL ROTATIONARY SYMMETRY TO IMPART USEFUL MOLECULAR ORIENTATION TO THE THERMOPLASTIC OF SAID ARTICLE, SAID METHOD COMPRISING INJECTING A HEAT PLASTIFIED MELT OF MOLECULARLY ORIENTATABLE, THERMOPLASTIC MATERIAL INTO A CLOSED MOLD WITH A CAVITY WHICH DEFINES SAID ARTICLE WHILE SIMULTANEOUSLY ROTATING AT LEAST ONE ELEMENT OF SAID MOLD, SAID INJECTION STEP BEING UNDER CONDITIONS TO INDUCE PERMANENT GENERALLY PREFERRED HELICOIDAL MOLECULAR ORIENTATION, SUBSTANTIALLY THROUGH THE WALL OF THE ARTICLE, THEREAFTER, PROVIDING SUFFICIENT TORQUE TO CONTINUE ROTATABLE MOVEMENT OF AT LEAST ONE ELEMENT COMPRISING SAID MOLD IN THE PERIOD AFTER SAID CAVITY HAS FILLED, SAID ROTATIONAL STEP IMPARTING A STRAIN ON SAID ARTICLE AS IT SOLIDIF ES SUBSTANTIALLY THROUGH THE THICKNESS THEREOF, TO THE EXTENT SAID ARTICLE PERMANENTLY ACCEPTS MOLECULAR ORIENTATION SUSTANTIALLY THROUGH ITS ENTIRE THICKNESS, THE DIRECTION OF THE ORIENTATION VARYING THROUGH THE THICKNESS OF THE ARTICLE, AND BEING ESSENTIALLY OF PREFFERED HOOP DIRECTION IN AN INNER LAYER THEREOF.
Claim 3
Dependent Claim
13 words
The method of claim 1 wherein said thermoplastic material comprises a styrene polymer.
Claim 4
Dependent Claim
32 words
The method of claim 1 wherein said rotational step is correlated with the orientation which is induced during the molded filling step in order to provide an article having generally balanced orientation.
Claim 5
Independent Claim
148 words
A method for injection molding a thermoplastic article having general rotational symmetry to impart useful molecular orientation to the thermoplastic of said article, said method comprising injecting a heat plastified melt of molecularly orientatable, thermoplastic material into a closed mold with a cavity which defines said article, said injection step being under conditions to induce permanent molecular orientation as the thermoplastic flows through the cavity, providing sufficient torque to rotatably move at least one element comprising said mold at least after said cavity has filled to impart strain on the thermal core of said article as it reaches its orientatable temperature range, to the extent said article permanently accepts molecular orientation substantially through its entire thickness, to thereby produce an essentially fully orientated article, the direction of the orientation varying through the thickness of the article, and being essentially of preferred hoop direction in an inner layer thereof.
Claim 6
Independent Claim
148 words
A method for injection molding a thermoplastic article having general rotational symmetry to impart useful molecular orientation to the thermoplastic of said article, said method comprising injecting a heat plastified melt of molecularly orientatable, thermoplastic material into a closed mold with a cavity which defines said article, said injection step being under conditions to induce permanent molecular orientation as the thermoplastic flows through the cavity, providing sufficient torque to rotatably move at least one element comprising said mold at least after said cavity has filled to impart strain on the thermal core of said article as it reaches its orientatable temperature range, to the extent said article permanently accepts molecular orientation substantially through its entire thickness, to thereby produce an essentially fully orientated article, the direction of the orientation varying through the thickness of the article, and being essentially of preferred hoop direction in an inner layer thereof.
Claim 7
Dependent Claim
13 words
The method of claim 4 wherein said thermoplastic material comprises a styrene polymer.
Claim 8
Dependent Claim
32 words
The method of claim 4 wherein said rotational step is correlated with the orientation which is induced during the mold filling step in order to provide an article having generally balanced orientation.
Claim 9
Dependent Claim
53 words
IN A METHOD FOR INJECTION MOLDING A THERMOPLASTIC ARTICLE HAVING GENERAL ROTATIONAL SYMMETRY WHEREIN A HEAT PLASTIFIED MELT OF A MOLECULARLY ORIENTATABLE, THERMOPLASTIC MATERIAL IS INJECTED UNDER PRESSURE INTO A CLOSED MOLD WITH A CAVITY WHICH DEFINES THE ARTICLE, THE INJECTION STEP BEING UNDER CONDITIONS TO INDUCE MOLECULAR ORIENTATION AS THE THERMOPLASTIC FLOWS
Claim 10
Dependent Claim
53 words
IN A METHOD FOR INJECTION MOLDING A THERMOPLASTIC ARTICLE HAVING GENERAL ROTATIONAL SYMMETRY WHEREIN A HEAT PLASTIFIED MELT OF A MOLECULARLY ORIENTATABLE, THERMOPLASTIC MATERIAL IS INJECTED UNDER PRESSURE INTO A CLOSED MOLD WITH A CAVITY WHICH DEFINES THE ARTICLE, THE INJECTION STEP BEING UNDER CONDITIONS TO INDUCE MOLECULAR ORIENTATION AS THE THERMOPLASTIC FLOWS
Claim 11
Dependent Claim
21 words
The method of claim 7 wherein said mold element is rotatably moved both before and after the mold cavity has filled.
References Cited (Backward Citations)
US2372177A
Cited
US3222439A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-22 | 1979-03-24 | 1979-09-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-22 | 1983-03-24 | 1983-09-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-22 | 1987-03-24 | 1987-09-23 | $7700.00 | Window Closed / Lapsed |