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Triglyceride Additives and Pelletizer Water Composition for Styrenic Block Copolymer Process

IP.com Disclosure Number: IPCOM000201662D
Publication Date: 2010-Nov-17
Document File: 5 page(s) / 331K

Publishing Venue

The IP.com Prior Art Database

Abstract

In the manufacture of styrenic block copolymers, the strongly basic residues of the metal alkyl initiator must be neutralized to prevent the degradation of antioxidant additives that stabilize the polymer. The resulting inorganic salts can lead to product contamination, and fouling and scale formation in processing equipment. The addition of triglycerides, or derivatives thereof, to the polymer has been found to aid neutralization and stabilization, reducing the amount of inorganic salts formed and the resulting issues.It has also been found that the use of a combination of a metal soap of a fatty acid, in combination with a low-foaming surfactant, as an anti-agglomerant in the pellet contact water during the pelletization of the styrenic block copolymers can minimize any foam or froth formation that can be a side effect of the addition of triglycerides.

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Publication for IP.com:

Triglyceride Additives and Pelletizer Water Composition for Styrenic Block Copolymer Process

Abstract

In the manufacture of styrenic block copolymers, the strongly basic residues of the metal alkyl initiator must be neutralized to prevent the degradation of antioxidant additives that stabilize the polymer.  The resulting inorganic salts can lead to product contamination, and fouling and scale formation in processing equipment.  The addition of triglycerides, or derivatives thereof, to the polymer has been found to aid neutralization and stabilization, reducing the amount of inorganic salts formed and the resulting issues.  It has also been found that the use of a combination of a metal soap of a fatty acid, in combination with a low-foaming surfactant, as an anti-agglomerant in the pellet contact water during the pelletization of the styrenic block copolymers can minimize any foam or froth formation that can be a side effect of the addition of triglycerides.

Detailed Description

The anionic polymerization of various monomers, including vinyl aromatic compounds, conjugated dienes, oxiranes, and derivatives of acrylates and methacrylates, to form random, tapered or block copolymers, is well known in the art.  A summary of suitable processes, monomers, modifiers, initators and solvents is given in Anionic Polymerization: Principals and Practical Applications by Henry L. Hsieh and Roderic P. Quirk (ISBN 0-8247-9253-7, Marcel Decker, Inc., New York, 1996), pages 71-127, pp 237-258 and pp 307-368.

Commercially produced examples of polymers produced by anionic polymerization include Styrenic block copolymers, such as styrene-butadiene-styrene or styrene-isoprene-styrene block copolymers.  Other examples include solution polybutadiene rubbers and solution styrene-butadiene rubbers (SBR).  These products are generally produced in a hydrocarbon solvent using an alkyllithium initiator, with n-butyllithium and sec-butyllithium being preferred examples.  A summary of such products is given in the reference cited above, pp 395-531.

Antioxidants and other stabilizers are added to the resulting polymers to ensure stability at storage and use conditions, maintaining the color and quality of the products.  However, the strongly basic residues of the metal alkyl initiator must first be neutralized to prevent the degradation of the additives.  Mineral acids may be used to neutralize these residues.  Examples of mineral acids which can be used for neutralization include, but are not limited to: boric acid, hydrochloric acid, nitric acid, phosphorous acid, sulfuric acid and phosphoric acid, with sulfuric or phosphoric acid being preferred examples.  A preferred process for production of styrenic block copolymers via anionic polymerization and the subsequent neutralization of the initiator residues is taught in

U. S.

5,225,493.

The inorganic salts, such as lithium phosphates or sulfates, resulting from the neutralization step can...