Block copolymer

Abstract

The present invention relates to a block copolymer (A) including a (meth)acrylic polymer block (a) and an acrylic polymer block (b). The (meth)acrylic polymer block (a) is preferably copolymerized with a monomer having a functional group having high cohesive force, such as a carboxyl group, so that the 5%-weight-loss temperature is 300° C. or more or the tensile strength is 3 MPa or more, and the hardness measured by a type A durometer according to JIS K6253 is 50 or less, and a compression set measured after 22 hours at 70° C. is 45% or less. The block copolymer (A) exhibits excellent thermal decomposition resistance and low compression set at high temperatures. The block copolymer (A) can be used as a soft material for automobile, and has low hardness, high adhesion, high oil resistance, high weather resistance, high heat resistance, high recycling property, high tensile properties, and high wax remover resistance.

1 . A block copolymer (A) comprising a (meth)acrylic polymer block (a) and an acrylic polymer block (b), and having a 5%-weight-loss temperature of 300° C. or more measured by thermogravimetric analysis at a heating rate of 10.0° C./min under a nitrogen stream at a flow rate of 50.0 ml/min.  
     
     
         2 . A block copolymer (A) comprising a (meth)acrylic polymer block (a) and an acrylic polymer block (b), and having a tensile strength of 3 MPa or more measured according to JIS K6301, a hardness of 50 or less measured by a type A durometer according to JIS K6253, and a compression set of 45% or less after 22 hours at 70° C.  
     
     
         3 . The block copolymer (A) according to  claim 1 , wherein the block copolymer (A) is a tri-block or di-block copolymer.  
     
     
         4 . The block copolymer (A) according to  claim 3 , wherein the block copolymer (A) is a (a)-(b)-(a) tri-block copolymer.  
     
     
         5 . The block copolymer (A) according to  claim 1 , wherein the number-average molecular weight is 30,000 to 500,000.  
     
     
         6 . The block copolymer (A) according to  claim 1 , wherein the ratio (Mw/Mn) of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) measured by gel permeation chromatography is 1.8 or less.  
     
     
         7 . The block copolymer (A) according to  claim 1 , comprising 5 to 90% by weight of the (meth)acrylic polymer block (a) and 95 to 10% by weight of the acrylic polymer block (b).  
     
     
         8 . The block copolymer (A) according to  claim 1 , comprising 10 to 40% by weight of the (meth)acrylic polymer block (a) and 90 to 60% by weight of the acrylic polymer block (b).  
     
     
         9 . The block copolymer (A) according to  claim 1 , wherein the block copolymer (A) is produced by controlled radical polymerization.  
     
     
         10 . The block copolymer (A) according to  claim 1 , wherein the (meth)acrylic polymer block (a) has a carboxyl group as a functional group (c).  
     
     
         11 . The block copolymer (A) according to  claim 1 , wherein the content of a carboxyl-containing monomer constituting the (meth)acrylic polymer block (a) is 5% by weight or more.  
     
     
         12 . A soft material for automobile comprising a block copolymer (A) comprising a (meth)acrylic polymer block (a) and an acrylic polymer block (b).  
     
     
         13 . The soft material for automobile according to  claim 12 , comprising the block copolymer (A) comprising 10 to 40% by weight of the (meth)acrylic polymer block (a) and 90 to 60% by weight of the acrylic polymer block (b).  
     
     
         14 . The soft material for automobile according to  claim 12 , wherein the (meth)acrylic polymer block (a) comprises methyl methacrylate and/or methacylic acid, and the acrylic polymer block (b) comprises n-butyl acrylate or a mixture of n-butyl acrylate, ethyl acrylate, and 2-methoxyethyl acrylate.  
     
     
         15 . The soft material for automobile according to  claim 14 , wherein the (meth)acrylic polymer block (a) comprises methyl methacrylate, and the acrylic polymer block (b) comprises n-butyl acrylate or a mixture of n-butyl acrylate, ethyl acrylate, and 2-methoxyethyl acrylate.  
     
     
         16 . The soft material for automobile according to  claim 14 , wherein the (meth)acrylic polymer block (a) comprises 50 to 100% by weight of methyl methacrylate and/or methacrylic acid and 0 to 50% by weight of a vinyl monomer copolymerizable therewith, and the acrylic polymer block (b) comprises 50 to 100% by weight of n-butyl acrylate or a mixture of n-butyl acrylate, ethyl acrylate, and 2-methoxyethyl acrylate and 0 to 50% by weight of a vinyl monomer copolymerizable therewith.  
     
     
         17 . The soft material for automobile according to  claim 12 , wherein the block copolymer (A) is produced by atom transfer radical polymerization.  
     
     
         18 . The soft material for automobile according to  claim 12 , wherein the block copolymer (A) is a tri-block copolymer.  
     
     
         19 . The soft material for automobile according to  claim 12 , wherein the block copolymer (A) has at least one hydroxyl group.  
     
     
         20 . The soft material for automobile according to  claim 12 , wherein the block copolymer (A) has at least one carboxyl group.  
     
     
         21 . The soft material for automobile according to  claim 12 , comprising the block copolymer (A) and a thermoplastic resin.  
     
     
         22 . The soft material for automobile according to  claim 21 , wherein the block copolymer (A) containing the thermoplastic resin is dynamically treated.  
     
     
         23 . An automobile interior member comprising the soft material for automobile according to  claim 12 .  
     
     
         24 . An automobile exterior member comprising the soft material for automobile according to  claim 12 .  
     
     
         25 . An inner layer material comprising the soft material for automobile according to  claim 12 .  
     
     
         26 . A molding material for automobile comprising the soft material for automobile according to  claim 12 .  
     
     
         27 . An automobile hollow-molded product comprising the soft material for automobile according to  claim 12 .  
     
     
         28 . An automobile hollow-molded boot or hose comprising the soft material for automobile according to  claim 12 .  
     
     
         29 . The block copolymer (A) according to  claim 2 , wherein the block copolymer (A) is a tri-block or di-block copolymer.  
     
     
         30 . The block copolymer (A) according to  claim 2 , wherein the number-average molecular weight is 30,000 to 500,000.  
     
     
         31 . The block copolymer (A) according to  claim 2 , wherein the ratio (Mw/Mn) of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) measured by gel permeation chromatography is 1.8 or less.  
     
     
         32 . The block copolymer (A) according to  claim 2 , comprising 5 to 90% by weight of the (meth)acrylic polymer block (a) and 95 to 10% by weight of the acrylic polymer block (b).  
     
     
         33 . The block copolymer (A) according to  claim 2 , comprising 10 to 40% by weight of the (meth)acrylic polymer block (a) and 90 to 60% by weight of the acrylic polymer block (b).  
     
     
         34 . The block copolymer (A) according to  claim 2 , wherein the block copolymer (A) is produced by controlled radical polymerization.  
     
     
         35 . The block copolymer (A) according to  claim 2 , wherein the (meth)acrylic polymer block (a) has a carboxyl group as a functional group (c).  
     
     
         36 . The block copolymer (A) according to  claim 2 , wherein the content of a carboxyl-containing monomer constituting the (meth)acrylic polymer block (a) is 5% by weight or more.