Process for the preparation of polybutadiene grafted with styrene and acrylonitrile and having a very low end content of unreacted residual monomers

• US 4,822,858 A
• Filed: 05/22/1986
• Issued: 04/18/1989
• Est. Priority Date: 05/24/1985
• Status: Expired due to Fees

• Current Assignee: Enichem Tecnoresine SPA
• Original Assignee: Enichem Tecnoresine SPA
• Inventors: Ferri, Gualtiero, Campana, Franco, Pivotto, Bruno
• Primary Examiner(s): Briggs, Sr., Wilbert J.
• Application Number:
  US06/866,146
• Time in Patent Office: 1,062 Days
• Field of Search: 525/316, 525/247, 525/246, 525/265, 525/252, 525/261, 525/264, 526/86, 526/87
• US Class Current: 525/246
• CPC Class Codes: C08F 279/04 Vinyl aromatic monomers and nitriles as the only monomers

Abstract

During the reaction of grafting of styrene and acrylonitrile to polybutadiene, the conversion of the graft monomers is increased from the values of 92÷94% usually obtained, to values very close to 98%, by carrying out a redox-type reaction additional to that provided by the process, in the presence of an additional aliquot of acrylonitrile and of catalytic system.

Claims

1. An emulsion polymerization process for the preparation of polybutadiene grafted with styrene and acrylonitrile monomers, having a very low end content of unreacted residual monomers, said process comprising conducting the graft copolymerization reaction with a mixture of acrylonitrile and styrene in the presence of a catalyst selected from cumene hydroperoxide, sodium persulfate, potassium persulfate, ammonium persulfate, di-isopropylbenzene hydroperoxide, and tert.butyl-peroxide, and a catalytic activator selected from dextrose, organic bases, salts and complexes containing iron ions, said acrylonitrile, styrene, catalyst and activator being continuously added to the polybutadiene, and wherein in the latter stages of the reaction but prior to the time when all of the styrene and acrylonitrile monomers have been added, there is added to the reaction an additional aliquot of acrylonitrile in an amount of from 0.1 to 3% by weight, and after the addition of the catalyst and activator is complete, there are added an additional aliquot of polymerization catalyst in an amount of from 0.02 to 0.4% by weight and an additional aliquot of polymerization activator in an amount of from 0.02 to 0.6% by weight, based on the weight of the monomers fed to the reaction.

2. The process of claim 1 wherein the additional aliquots of the polymerization catalyst and the polymerization activator are added to the reaction after the addition of the additional aliquot of acrylonitrile.

3. The process of claim 2 wherein the additional aliquots of the polymerization catalyst and the polymerization activator are added at the conclusion of the introduction of the polymerization catalyst to the reaction.

4. The process of claim 2 wherein the additional aliquots of polymerization catalyst and polymerization activator are added together to the reaction.

5. The process of claim 1, wherein the complex containing iron ions is Iron-EDTA.

6. The process of claim 1, wherein the additional amounts of acrylonitrile, polymerization catalyst and polymerization activator are added to the reaction mixture in the following amounts:

acrylonitrile from 1.3 to 1.5% by weight;

catalyst from 0.03 to 0.05% by weight;

activator from 0.04 to 0.06% by weight.

7. The process of claim 1, wherein the mixture of styrene and acrylonitrile is present in an amount of 10 to 90% by weight, said mixture containing 50 to 90% by weight of styrene;

and polybutadiene is present in an amount of 90 to 10% by weight.

8. The process of claim 1, wherein the reaction is conducted at a temperature of from 60°

to 95°

C.

9. The process of claim 7, wherein the addition of the additional amounts of acrylonitrile, polymerization catalyst and polymerization activator is conducted at a temperature higher than the initial reaction temperature and within the range of from 80°

to 96°

C.