Modifying agent, method for producing modified conjugated diene polymer using modifying agent, and modified conjugated diene polymer

Abstract

Provided are a modifying agent obtained by subjecting a silicon-containing compound having a protected primary amino group and at least two hydrolyzable groups to complete condensation, a method of producing a modified conjugated diene-based polymer, a modified conjugated diene-based polymer obtained by the production method, a rubber composition using the polymer, and a pneumatic tire. The modified conjugated diene-based polymer has excellent low heat generating property and abrasion resistance, and the rubber composition is obtained by using the modified conjugated diene-based polymer and the pneumatic tire is obtained by using the rubber composition.

1 . A modifying agent obtained by subjecting a silicon-containing compound having a protected primary amino group and at least two hydrolyzable groups to complete condensation. 
     
     
         2 . The modifying agent according to  claim 1 , wherein the hydrolyzable functional groups each are a group selected from the group consisting of an alkoxy group having 1 to 12 carbon atoms, a phenoxy group and a benzyloxy group, or a halogen atom. 
     
     
         3 . The modifying agent according to  claim 1 , wherein the modifying agent comprises a compound represented by a general formula (1) 
       
         
           
           
               
               
           
         
       
       where R 1  and R 2  each represent a divalent aliphatic hydrocarbon group having 1 to 20 carbon atoms, a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms, or a single bond, and may be identical to or different from each other, R 3 , R 4 , and R 5  each represent a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and may be identical to or different from one another, A 1  represents a group for bonding the modifying agent and a conjugated diene-based polymer by adding to, or substituting for, an active site of the conjugated diene-based polymer, B′ represents a primary amino group protected with a hydrolyzable protective group, a+b+c=2, a represents 1 to 2, b represents 0 to 1, and n represents 2 to 20; or (2) 
       
         
           
           
               
               
           
         
       
       where R 6  and R 11  each represent a divalent aliphatic hydrocarbon group having 1 to 20 carbon atoms, a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms, or a single bond, and may be identical to or different from each other, R 8  represents a divalent aliphatic hydrocarbon group having 1 to 20 carbon atoms or a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms, R 7 , R 9 , R 10 , R 12 , and R 13  each represent a monovalent aliphatic hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 18 carbon atoms, and may be identical to or different from one another, A 2  represents a group for bonding the modifying agent and a conjugated diene-based polymer by adding to, or substituting for, an active site of the conjugated diene-based polymer, B 2  represents a primary amino group protected with a hydrolyzable protective group, B 3  represents a linear, branched, alicyclic, or aromatic, monovalent hydrocarbon group having 1 to 30 carbon atoms and having a functional group selected from the group consisting of an isocyanate group, a thioisocyanate group, an imine residue, an amide group, a cyclic secondary amino group, an onium salt residue of a cyclic secondary amine, a non-cyclic secondary amino group, an onium salt residue of a non-cyclic secondary amine, an isocyanuric acid triester residue, a cyclic tertiary amino group, a non-cyclic tertiary amino group, a nitrile group, a pyridine residue, an onium salt residue of a cyclic tertiary amine, and an onium salt residue of a non-cyclic tertiary amine, or a linear, branched, alicyclic, or aromatic, monovalent hydrocarbon group having 1 to 30 carbon atoms which may contain at least one kind of heteroatom selected from an oxygen atom, a sulfur atom, and a phosphorus atom, a1+b1+c1=2, a1 represents 1 to 2, b1 represents 0 to 1, a2+b2+c2=2, a2, b2, and c2 each represent 0 to 2, and p and q each independently represent 1 to 10. 
     
     
         4 . A method of producing a modified conjugated diene-based polymer, comprising:
 a modifying step of causing the modifying agent according to  claim 1  to react with an active site of a conjugated diene-based polymer having the active site to modify the polymer; and   a deprotecting step to be performed after completion of the modifying step.   
     
     
         5 . The method of producing a modified conjugated diene-based polymer according to  claim 4 , comprising a hydrolyzing step between the modifying step and the deprotecting step, or after the deprotecting step or simultaneously with the deprotecting step. 
     
     
         6 . The method of producing a modified conjugated diene-based polymer according to  claim 4 , wherein 10% or more of alkoxysilyl groups are converted into silanol groups by hydrolysis. 
     
     
         7 . The method of producing a modified conjugated diene-based polymer according to  claim 4 , wherein the conjugated diene-based polymer having the active site is obtained by subjecting a conjugated diene compound alone, or the conjugated diene compound and an aromatic vinyl compound, to anionic polymerization with an organic alkali metal compound as a polymerization initiator. 
     
     
         8 . A modified conjugated diene-based polymer obtained by the production method according to  claim 4 . 
     
     
         9 . A rubber composition, comprising the modified conjugated diene-based polymer according to  claim 8 . 
     
     
         10 . The rubber composition according to  claim 9 , further comprising a condensation-accelerating agent. 
     
     
         11 . The rubber composition according to  claim 10 , wherein the condensation-accelerating agent is added at a time of synthesis of the modified conjugated diene-based polymer and/or at a time of preparation of the rubber composition. 
     
     
         12 . The rubber composition according to  claim 10 , wherein a compounding amount of the condensation-accelerating agent is 0.1 to 10 parts by mass based on 100 parts by mass of the rubber component of the rubber composition. 
     
     
         13 . The rubber composition according to  claim 9 , comprising 10 to 200 parts by mass of a reinforcing filler based on 100 parts by mass of a rubber component formed of 10 to 100 mass % of the modified conjugated diene-based polymer according to  claim 8  and 90 to 0 mass % of a diene-based rubber. 
     
     
         14 . A pneumatic tire obtained by using the rubber composition according to  claim 9 .