K-Resin SBC

The development of high styrene content styrene-butadiene copolymers (SBCs), such as K-Resin SBC, is best thought of as a branch off the history of anionic polymerization and rubber. A number of excellent reviews cover this aspect of the subject in great detail, and should be obtained for detailed examination of the history of rubber and anionically synthesized rubber polymers [1-3]. What follows is a brief overview to fit the high styrene content SBC into a historical context. 

K-Resin SBC was invented by Alonzo Kitchen, a research chemist at Phillips Petroleum Research and Development laboratories. With inventorship came the opportunity to name the new resin, which he called K-Resin . The first pilot plant resins were made in 1967, and commercial samples were prepared for test marketing in 1968. Commercial production started in October of 1972 at the SBC plant in Borger, Texas, on a 10 million pound per year capacity line. Initially, the solution product was steam stripped to remove the hydrocarbon solvent, but this left a significant haze in the resin. The finishing system was quickly converted to a devolatilizing extruder. Commercial production continued at this plant until 1979, ending with the opening of a new production facility at Adams Terminal (later renamed the Houston Chemical Complex) in Pasadena, Texas. The new plant had a nameplate capacity of 120 million pounds per year. Plant expansions increased the production capacity in 1988 and 1994 to a total nameplate capacity around 300 million pounds per year. 

K-Resin SBC synthesis is a batch anionic solution polymerization of styrene and 1,3-butadiene using an n-butyllithium (NBL) initiator in a process referred to as living polymerization . Although often referred to as a catalyst, each NBL gives rise to a distinct polymer chain. Polymer chains grow by adding monomer... 

Figure 22.5 Film properties of K-Resin SBC grades (DK11 and DK13) 1 mil film...

Table 22.10 Physical properties 50 50 K-Resin SBC-GPPS 20 mil blended sheet modified with Dow XL 8028 HIPS...

Medical Applications of K-Resin , SBC Technical Service Memorandum 292, Chevron Phillips Chemical Co., Bartlesville, OK. 

Table 22.7 Physical properties of blends of K- Resin H SBC and styrene-acrylonitrile copolymer"... 

Styrene-butadiene block copolymers (SBC) with a high (70-85 %) styrene content are commercially produced and marketed as transparent, stiff, and tough thermoplastic resins under the trade names of Styrolux (Styrolution), K-Resin (Chevron-Phillips), Finaclear (Total petrochemical), and Clearene (Denka-Kaguku). Unlike other more elastomeric types of styrene-butadiene block copolymers, the rigid SBC resins contain only <25 % polybutadiene rubber content. Structurally, these SBC polymers are composed of polystyrene (S) and polybutadiene (B) blocks, linked together in an unsymmetrical star-block [(S-B)x] structure. 

A Killion 50 mm (2 in) single screw extruder was used. The two materials were an Equistar Petrothene low density polyethylene (LDPE) and a Chevron Phillips K-Resin styrene-butadiene copolymer (SBC). Figure 3 shows material properties as provided by the supplier. 

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