Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2002-10-10
2004-07-20
Teskin, Fred (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S288000, C525S291000, C525S293000, C525S301000, C525S312000, C525S375000, C525S379000, C526S173000, C526S178000, C526S180000, C526S181000
Reexamination Certificate
active
06765065
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a process for producing a modified polymer rubber having superior impact resilience. The modified polymer rubber obtained according to said process is most suitable for motorcar tires having superior fuel cost saving.
BACKGROUND OF THE INVENTION
A styrene-butadiene copolymer obtained by emulsion polymerization is known as rubber used for motorcar tires. However, said copolymer has a problem that motorcar tires comprising said copolymer are not satisfactory from a viewpoint of fuel cost saving, because the copolymer does not have sufficient impact resilience.
In order to obtain rubber having superior impact resilience, JP-A60-72907 discloses a process, which comprises copolymerizing butadiene and styrene in a hydrocarbon solvent using an organolithium compound as an initiator, and a Lewis base such as ether as a microstructure controlling agent.
Further, Japanese Patent No. 2540901 proposes a process, which comprises reacting an alkali metal, which is bound at the end of a diene polymer rubber, with a specific acrylamide to obtain a modified diene polymer rubber having improved impact resilience.
Furthermore, Japanese Patent Application No. 2000-328813 discloses a process, which comprises reacting an alkali metal, which is bound at the end of a diene polymer rubber, with a specific amine to obtain a modified diene polymer rubber having improved impact resilience and processability.
However, recently, a level of a demand for fuel cost saving of motorcar tires is higher from an environmental view, and therefore, any of the above-mentioned copolymer rubbers can hardly meet such a demand.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a process for producing a modified polymer rubber having superior impact resilience.
The present invention provides a process (the process being hereinafter referred to as “Process-1”) for producing a process for producing a modified polymer rubber having modified both ends, which comprises the steps of:
(1) reacting a compound represented by the following formula (1) with an organic alkali metal compound, to produce a chemical species,
wherein R
1
is an amino, alkoxy, silyloxy, acetal; carboxyl or mercapto group or a group derived from any of these groups,
(2) polymerizing a conjugated diene monomer or a combination of a conjugated diene monomer with an aromatic vinyl monomer in the presence of the chemical species to produce an active polymer having an alkali metal at an end thereof, and
(3) reacting the active polymer with a functional group-carrying modifying agent in a hydrocarbon solvent to produce the modified polymer rubber having modified both ends.
The present invention also provides a process (the process being hereinafter referred to as “Process-2”) for producing a modified polymer rubber having modified both ends, which comprises the steps of:
(1) reacting a compound represented by the above formula (1) with an organic alkali metal compound to produce a chemical species,
(2) polymerizing a conjugated diene monomer or a combination of a conjugated diene monomer with an aromatic vinyl monomer in the presence of the chemical species to produce an active polymer having an alkali metal at an end thereof,
(3) reacting the active polymer with a compound represented by the above formula (1) to produce an active polymer, each of whose both terminals is modified and has an alkali metal, and
(4) reacting the active polymer with a functional group-carrying modifying agent in a hydrocarbon solvent to produce the modified polymer rubber having modified both ends.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Examples of a conjugated diene compound used in the present invention are 1,3-butadiene, isoprene, 1,3-pentadiene (piperylene), 2,3-dimethyl-1,3-butadiene and 1,3-hexadiene. Of these, 1,3-butadiene and isoprene are preferable from a viewpoint of availability and physical properties of a modified polymer rubber obtained.
Examples of an aromatic vinyl compound used in the present invention are styrene, &agr;-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene and divinylnaphthalene. Of these, styrene is preferable from a viewpoint of availability and physical properties of a modified polymer rubber obtained.
In the above formula (1), a preferable R, is an N,N-dimethylamino group, an N,N-diethylamino group, an N,N-dipropylamino group, an N,N-dibutylamino group or a morpholino group.
Examples of the compound represented by the formula (1) are 1-(4-N,N-dimethylaminophenyl)-1-phenylethylene, 1-(4-N,N-diethylaminophenyl)-1-phenylethylene, 1-(4-N,N-dipropylaminophenyl)-1-phenylethylene, 1-(4-N,N-dibutylaminophenyl)-1-phenylethylene and 1-(4-morpholinophenyl)-1-phenylethylene. Particularly, 1-(4-N,N-dimethylaminophenyl)-1-phenylethylene and 1-(4-morpholinophenyl)-1-phenylethylene are preferable from a viewpoint of remarkable improvement of fuel cost saving.
Although a compound having two polar groups can be also used as the compound represented by the formula (1) to attain the objects of the present invention, a compound having one polar group is industrially preferable from a viewpoint of solubility of said compound into a hydrocarbon solvent.
Examples of the organic alkali metal compound used in the present invention are hydrocarbon compounds containing a metal such as lithium, sodium, potassium, rubidium and cesium. Among them, preferable are lithium compounds or sodium compounds having 2 to 20 carbon atoms.
Specific examples thereof are ethyllithium, n-propyllithium, iso-propyllithium, n-butyllithium, sec-butyllithium, t-octyllithium, n-decyllithium, phenyllithium, 2-naphthyllithium, 2-butyl-phenyllithium, 4-phenyl-butyllithium, cyclohexyllithium, 4-cyclopentyllithium and 1,4-dilithio-butene-2. Among them, n-butyllithium or sec-butyllithium is preferable to obtain an active polymer having a narrow molecular weight distribution at a rapid reaction rate.
When a combination of a conjugated diene monomer with an aromatic vinyl monomer is used in the step (2) in the present invention, a weight ratio of conjugated diene compound/aromatic vinyl monomer is preferably from 50/50 to 90/10, and more preferably from 55/45 to 85/15. When the ratio is less than 50/50, the active polymer obtained may be insoluble in the hydrocarbon solvent, and as a result, it may be impossible to carry out a homogeneous polymerization. When the ratio exceeds 90/10, strength of the active polymer obtained may decrease.
A polymerization method in the step (2) is not particularly limited, and maybe a conventional one. In said step, it is permitted to use conventional solvents and additives usually used in the art such as hydrocarbon solvents; randomizers; and additives used for controlling a content of a vinyl bond (which bond is derived from the conjugated diene monomer) in the active polymer obtained.
As the above-mentioned additives used for controlling a content of a vinyl bond, Lewis basic compounds are exemplified. As said compounds, an ether or a tertiary amine is preferable from a viewpoint of industrial availability.
Examples of the above-mentioned ethers are cyclic ethers such as tetrahydrofuran, tetrahydropyran and 1,4-dioxane; aliphatic mono ethers such as diethyl ether and dibutyl ether; aliphatic diethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol diethyl ether and diethylene glycol dibutyl ether; and aromatic ethers such as diphenyl ether and anisole,
Examples of the above-mentioned tertiary amines are triethylamine, tripropylamine, tributylanine, N,N,N′,N′-tetramethylethylenediamine, N,N-diethylaniline, pyridine and quinoline.
Examples of the functional group-carrying modifying agent (hereinafter simply referred to as “modifier”) used in the present invention are cyclic ether structure-carrying compounds such as ethylene oxide, propylene oxide, glycidyl methaorylate, tetraglycidyl-m-xylenediamine, tetraglycidyl-1,3-bisaminomethylcyclohexane, tetraglycidyldiaminodiphenyl
Inagaki Katsunari
Mabe Seiichi
Oshima Mayumi
Sughrue & Mion, PLLC
Sumitomo Chemical Company Limited
Teskin Fred
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