Claims
- 1. A method of producing polylaurolactam powders comprising:
- (a) polymerizing laurolactam in the presence of about 2 to 10 percent by weight of water, based on said laurolactam, about 0.3 to 0.7 percent by weight of phosphoric acid, based on said laurolactam and at a temperature of about 265.degree. to 300.degree. C. in the absence of chain stabilizers under an internal pressure of about 14 to 25 bars to a polylaurolactam having a relative viscosity of about 1.25 to 1.45 measured in a 0.5 percent meta-cresol solution at 25.degree. C.;
- (b) granulating said polylaurolactam of (a);
- (c) extracting said granulated polylaurolactam with ethanol or methanol at a temperature of about 25.degree. to 70.degree. C.;
- (d) reducing to powdered form said extracted polylaurolactam of (c) at a temperature of about 0.degree. to 45.degree. C. to obtain approximately round powder grains; and
- (e) further polymerizing said round powder grains at a temperature between about 140.degree. C. and below the melting point of said polyalurolactam to said polylaurolactam powders having a relative viscosity of about 1.55 to 1.65 measured in a 0.5 percent meta-cresol solution at 25.degree. C.
- 2. A method of producing polylaurolactam powders comprising:
- (a) polymerizing laurolactam in the presence of about 2 to 10 percent by weight of water based on said laurolactam, about 0.3 to 0.7 percent by weight of phosphoric acid based on said laurolactam and at a temperature of about 265.degree. to 300.degree. C., in the absence of chain stabilizers under an internal pressure of about 14 to 25 bars to a polylaurolactam having a relative viscosity of about 1.25 to 1.45 measured in a 0.5 percent meta-cresol solution at 25.degree. C.;
- (b) granulating said polyalurolactam of (a);
- (c) extracting said granulated polylaurolactam with ethanol or methanol at a temperature of about 25.degree. to 70.degree. C.;
- (d) grinding the extracted polyalurolactam of (c) at a temperature of about 0.degree. to 45.degree. C. to obtain approximately round powder grains; and
- (e) further polymerizing said round powder grains at a temperature between about 140.degree. C. and below the melting point of said polylaurolactam to said polylaurolactam powders having a relative viscosity of about 1.55 to 1.65 measured in a 0.5 percent meta-cresol solution at 25.degree. C.
- 3. The method of claim 2, wherein said polylaurolactam powders are sized to a particle distribution of between greater than about 60 and less than about 350 microns.
- 4. The method of claim 2, wherein said relative viscosity of step (a) is 1.33 to 1.43, and said relative viscosity of step (e) is 1.50 to 1.65.
- 5. The method of claim 2, wherein said relative viscosity of step (a) is 1.35 to 1.40 and said relative viscosity of step (e) is 1.55 to 1.63.
- 6. The method of claim 2, wherein the grinding step (d) is carried out at a temperature of about 10 .degree. to 35.degree. C.
- 7. The method of claim 2, wherein the grinding step (d) is carried out at a temperature of about 15.degree. to 25.degree. C.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2545267 |
Oct 1975 |
DEX |
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CROSS REFERENCES TO RELATED APPLICATIONS
This application is a division of application Ser. No. 722,110, filed Sept. 10, 1976, now U.S. Pat. No. 4,143,025.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
3255148 |
Sievenpiper et al. |
Jun 1966 |
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3564599 |
Schaaf et al. |
Feb 1971 |
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3910861 |
Wolvers |
Oct 1975 |
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Non-Patent Literature Citations (1)
Entry |
"Eveil de Berney", French Newspaper, Jan. 22, 1970, p. 3. |
Divisions (1)
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Number |
Date |
Country |
Parent |
722110 |
Sep 1976 |
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