Claims
- 1. A continuous process for polymerizing acrylonitrile and butadiene monomers to produce substantially consistent composition and component distribution NBR rubbers having a bound acrylonitrile content of about fifty percent by weight comprising the steps of:
- continuously charging quantities of acrylonitrile monomer and butadiene monomer in a ratio of about 80 parts acrylonitrile to 20 parts.+-.10% butadiene and quantities of at least one polymerization initiator, water and at least one emulsifying agent to a first reaction vessel in amounts effective to produce a latex;
- continuously copolymerizing the acrylonitrile and butadiene monomers in the first reaction vessel to achieve and maintain a ratio of unconverted monomers in the range of about 70 to 90 parts acrylonitrile to about 30 to 10 parts butadiene;
- continuously transferring the copolymerized acrylonitrile and butadiene, acrylonitrile monomer, butadiene monomer, polymerization initiator, water and emulsifying agent from the first reaction vessel to a second reaction vessel;
- continuously charging additional monomer consisting essentially of butadiene to the second reaction vessel effective to maintain a ration of unconverted monomers in the range of about 70 to 90 parts acrylonitrile to about 30 to 10 parts butadiene; and
- continuing the steps of copolymerizing, transferring and adding butadiene until the total quantity of butadiene added is equal to the amount necessary to obtain monomer conversion of about 75% to 90% and final copolymer composition of about 50% acrylonitrile in a last reaction vessel.
- 2. The continuous process of claim 1, wherein the quantity of butadiene monomer charged to the first reaction vessel is about one-fourth the quantity of acrylonitrile monomer charged.
- 3. The continuous process of claim 1, wherein the polymerization initiator is a redox initiator.
- 4. The continuous process of claim 1, wherein the polymerization initiator is a thermal initiator.
- 5. The continuous process of claim 1, wherein the emulsifying agent is an anionic emulsifier.
- 6. The continuous process of claim 1, further comprising the step of adding a shortstopping agent to terminate polymerization in the last reaction vessel.
- 7. The continuous process of claim 1, wherein the shortstopping agent is added at a conversion of not greater than 90 parts of total monomer.
- 8. The continuous process of claim 1, wherein the shortstopping agent is sodium dimethyldithiocarbamate or diethyl hydroxyl amine or a mixture of the two.
- 9. The continuous process of claim 1 including the steps of recovering the nitrile butadiene rubber produced by coagulating the polymer latex with aqueous solutions of acid or salt to give processable polymer crumb.
- 10. The continuous process of claim 9 in which the coagulation serum has a pH of 3 and contains 3 parts per hundred rubber of aluminum sulfate.
- 11. The continuous process of claim 9 in which calcium chloride is the coagulation salt.
- 12. The continuous process of claim 9 including the further steps of dewatering, pelletizing and partitioning the polymer.
Parent Case Info
This is a continuation of application Ser. No. 08/242,807 filed May 16, 1994, now abandoned, which is a continuation of application Ser. No. 08/072,249, filed Jun. 4, 1993, now abandoned, which is a continuation of application Ser. No. 07/918,921, filed Jul. 22, 1992, now abandoned, which is a continuation of application Ser. No. 07/730,028, filed Jul. 12, 1991, now abandoned, which is a continuation of application Ser. No. 07/441,284, filed Nov. 27, 1989, now abandoned.
US Referenced Citations (5)
Foreign Referenced Citations (2)
Number |
Date |
Country |
56-16502 |
Dec 1983 |
JPX |
601587 |
May 1948 |
GBX |
Non-Patent Literature Citations (2)
Entry |
Hawley's Condensed Chemical Dictionary, Eleventh Edition, Van Nostrand Reinhold, New York, p. 1146, 1987. |
The Condensed Chemical Dictionary, Tenth Edition, Revised by Gessner G. Hawley, Van Nostrand Reinhold, New York, 1981, p. 918. |
Continuations (5)
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Number |
Date |
Country |
Parent |
242807 |
May 1994 |
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Parent |
72249 |
Jun 1993 |
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Parent |
918921 |
Jul 1992 |
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Parent |
730028 |
Jul 1991 |
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Parent |
441284 |
Nov 1989 |
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