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
2002-07-22
2003-07-15
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...
C525S242000, C525S271000, C526S082000, C526S084000, C526S336000, C526S340000
Reexamination Certificate
active
06593429
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a polymer having a combined linear and nonlinear structure and method of preparation. More particularly, the present invention relates to a linear and nonlinear polymer (i.e., having a combined linear, branched, radial and star-like structure) that is prepared from a vinyl aromatic monomer or a conjugated diene monomer and a multifunctional compound by anionic polymerization, and its preparing method.
2. Related Prior Art
The nonlinear structure of a polymer generally affects crystallinity, melting point, mechanical properties, viscoelastic property, solution property or melting property of the polymer. Namely, nonlinear polymers are much superior in processability and workability to linear polymers having the same molecular weight owing to low melt and solution viscosity and also in mechanical properties to linear polymers having the same melt viscosity and solution viscosity.
A nonlinear polymer such as a branched polymer is prepared by different polymerization methods, including anionic polymerization and free radical polymerization. Among these polymerization methods, free radical polymerization hardly produces a polymer having a desired nonlinear structure due to difficulty in controlling the molecular weight and nonlinearity(e.g., branch density) of the polymer. Thus nonlinear polymers are usually prepared by anionic polymerization that is easy to control.
An example of using anionic polymerization in the preparation of a nonlinear polymer is disclosed in U.S. Pat. No. 5,700,887, which describes a method of preparing a nonlinear polystyrene polymer that includes contacting styrene with sodium naphthalene used as a difunctional anionic initiator for anionic initiation, and adding a mixture of difunctional 1,4-bis(chloromethyl)benzene and trifunctional 1,3,5-tris(chloromethyl)benzene as a multifunctional compound.
In this preparation method, a polar solvent is used because the difunctional anionic initiator has a low solubility in non-polar solvents. But the use of a polar solvent causes difficulty in controlling the fine structure of the polymer prepared from the conjugated diene monomer and is actually limited in the range of applications. This method also requires using two different multifunctional compounds in combination so as to produce a polymer having a combined nonlinear structure, including star-like and radial structures. The use of multifunctional halide compounds in this preparation method results in production of lithium chloride as a byproduct, which has an adverse effect on the thermal stability or color stability of the polymer product.
Besides, the chain reaction such as anionic polymerization, a step reaction can also be applied to the preparation of nonlinear polymers, in which case monomers having at least two functional groups are used.
Unlike anionic polymerization, the step reaction requires an accurate control of equivalents of reactants so as to produce polymers of a desired structure and is disadvantageously susceptible to runaway reaction and gelation.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a polymer prepared by anionic polymerization that (a) overcomes the shortcoming of free radical polymerization that has difficulty in controlling reactivity and hence the linearity (e.g., branch density, etc.) or molecular weight of the product, (b) avoids a step reaction susceptible to runaway reaction and gelation, and (c) involves the use of a non-polar solvent as a polymerization solvent for wide applications, without producing any salts (e.g., lithium chloride) that may adversely affect the properties of the final product such as thermal stability and resistance to discoloration.
It is another object of the present invention to provide a method for preparing a multi-component polymer having a combined linear and nonlinear structure using an anionic initiator, a vinyl aromatic monomer or a conjugated diene monomer and a multifunctional compound.
More specifically, the object of the present invention is providing a combined linear and nonlinear polymer (i.e., having a combined linear, branched, radial and star-like structure) from a vinyl aromatic monomer or a conjugated diene monomer and a multifunctional compound by anionic polymerization, and a method for preparing the combined linear and nonlinear polymer (i.e., having a combined linear, branched, radial and star-like structure) using anionic polymerization that adequately controls the reactivity of the multifunctional compound, otherwise hard to control the reactivity in the conventional anionic polymerization method, and thereby overcomes such a problem with free radical polymerization, step polymerization, or the conventional anionic polymerization as difficulty in control of reactivity and instability of properties.
To achieve the objects of the present invention, there is provided a vinyl aromatic or conjugated diene polymer having a combined linear and nonlinear structure, the polymer being represented by the following formula 1:
(P+PnD)
−+
Li Formula 1
wherein P is a polymer of a monovinyl aromatic monomer or a conjugated diene monomer; PD is a nonlinear polymer having a combined linear, branched, radial and star-like structure due to a multifunctional compound D bonded to the polymer P; n is an integer ranging from 2 to 10 and represents the average number of bonds between the monovinyl aromatic or conjugated diene polymer P and the multifunctional compound D; (P+PnD)
−
represents a vinyl aromatic or conjugated diene polymer having a combined linear and nonlinear structure; and
+
Li represents a counter metal ion of the active anion (P +PnD)
−
.
The combined linear and nonlinear polymer represented by the formula 1 is prepared by a method using an anionic initiator, a vinyl aromatic monomer or a conjugated diene monomer and a multifunctional compound, the method including: (1) adding the monovinyl aromatic monomer or the conjugated diene monomer and the anionic initiator, (2) adding the multifunctional compound and the conjugated diene monomer or the vinyl aromatic monomer; and (3) adding an active hydrogen compound.
Now, the present invention will be described in further detail as follows.
The combined linear and nonlinear polymer (i.e., having a combined linear, branched, radial and star-like structure) according to the present invention is represented by (P+PnD)
−+
Li, where P is a polymer of a monovinyl aromatic monomer or a conjugated diene monomer; PD is a nonlinear polymer having a combined linear, branched, radial and star-like structure due to a multifunctional compound D bonded to the polymer P; n is an integer ranging from 2 to 10 and represents the average number of bonds between the monovinyl aromatic or conjugated diene polymer P and the multifunctional compound D; and
+
Li represents a metal ion as a partner of the active anion (P+PnD)
−
.
In the preparation of the polymer of the present invention, the vinyl aromatic monomer contains 8 to 12 carbons and specifically includes styrene, &agr;-methylstyrene, o-vinylstyrene, &rgr;-vinylstyrene, &rgr;-t-butylstyrene, 4-ethylstyrene, 3-ethylstyrene, 4-t-butylstyrene, 2,4-dimethylstyrene, or mixtures of them. Among these monomers, styrene is most preferred.
The conjugated diene monomer contains 4 to 6 carbons and specifically includes 1,3-butadiene, 2-methyl-1,3-butadiene (what is called “isoprene”), 2-ethyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, or mixtures of them. Among these monomers, 1,3-butadiene and 2-methyl-1,3-butadiene are preferable.
The anionic initiator useful for anionic polymerization of the vinyl aromatic monomer or the conjugated diene monomer includes an organic lithium initiator represented by RM, where R is C
4
to C
8
alkyl or cycloalkyl and M is an alkali metal. Namely, the organic lithium initiator may be any one that is normally used for anionic polymerization, and n-butyl lithium and se
Kim Jong-Geun
Kim Sam-Min
Park Jong-Hyun
Davidson Davidson & Kappel LLC
Korea Kumho Petrochemical Co. Ltd.
Teskin Fred
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