Process for preparing linear block copolymer

Abstract

The present invention relates to a linear block copolymer and a process for preparing the same, particularly to a linear block copolymer and a process for preparing the same which can improve transmissivity of a block copolymer and remarkably lower a Haze value by introducing a vinyl aromatic hydrocarbon to conduct primary polymerization, simultaneously introducing a vinyl aromatic hydrocarbon and a conjugated diene monomer therein to conduct secondary polymerization, and introducing a vinyl aromatic hydrocarbon therein to conduct tertiary polymerization, thereby locating a conjugated diene/vinyl aromatic hydrocarbon copolymer block in a block copolymer.

What is claimed is:  
     
         1 . A linear block copolymer represented by the following Chemical Formula 1:  
       A 1 -B 1 -(B/A)-A 2 -A 3   [Chemical Formula 1] (wherein    A 1 , A 2 , and A 3  are independently vinyl aromatic hydrocarbon blocks having average molecular weights of 100˜100,000,    B 1  is a conjugated diene block having an average molecular weight of 100˜100,000, and    (B/A) is conjugated diene/vinyl aromatic hydrocarbon copolymer block having an average molecular weight of 100˜100,000.).    
     
     
         2 . The linear block copolymer according to  claim 1 , wherein the ratio of A 1  block and (A 2 +A 3 ) block of the copolymer is 0.1˜10.  
     
     
         3 . The linear block copolymer according to  claim 1 , wherein the ratio of vinyl aromatic hydrocarbon/conjugated diene monomer in the block copolymer is 25:75˜50:50.  
     
     
         4 . The linear block copolymer according to  claim 1 , wherein the average molecular weight of the linear block copolymer is 400˜400,000.  
     
     
         5 . The linear block copolymer according to  claim 1 , wherein the vinyl aromatic hydrocarbon is selected from a group consisting of styrene, α-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 1-vinyinaphthalene, 4-cyclohexylstyrene, 4-(p-methylphenyl)styrene, 1-vinyl-5-hexylnaphthalene, and a mixture thereof.  
     
     
         6 . The linear block copolymer according to  claim 1 , wherein the conjugated diene monomer is selected from a group consisting of 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, piperylene, 3-butyl-1,3-octadiene, isoprene, 2-phenyl-1,3-butadiene, and a mixture thereof.  
     
     
         7 . The linear block copolymer according to  claim 1 , wherein the organolithium compound is selected from a group consisting of methyl lithium, ethyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, n-decyl lithium, tert-octyl lithium, phenyl lithium, 1-naphthyl lithium, n-eicosyl lithium, 4-butylphenyl lithium, 4-tollyl lithium, cyclohexyl lithium, 3,5-di-n-heptylcyclohexyl lithium, 4-cyclopentyl lithium, and a mixture thereof.  
     
     
         8 . A process for preparing a linear block copolymer comprising the steps of: 
 a) introducing a vinyl aromatic hydrocarbon in a reactor to polymerize until at least 99% of monomers are consumed;    b) simultaneously introducing a vinyl aromatic hydrocarbon and a conjugated diene in the reactor of the step a) to polymerize until at least 99% of monomers are consumed; and    c) introducing a vinyl aromatic hydrocarbon in the reactor of the step b) to polymerize until at least 99% of monomers are consumed.    
     
     
         9 . The process for preparing a linear block copolymer according to  claim 8 , wherein the polymerization of steps a), b), and c) are conducted at a temperature range of −50˜150° C.