Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2002-07-18
2003-05-20
Pezzuto, Helen L. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S209000, C526S217000, C526S236000, C526S304000, C526S307000, C526S307700, C526S320000, C526S328500, C526S329200, C526S329600
Reexamination Certificate
active
06566466
ABSTRACT:
BACKGROUND OF THE PRESENT INVENTION
The present invention is directed to a novel method for the, production of a graft copolymer or acrylate polymer blend in the presence of at least one liquid diluent.
It is increasingly becoming desirable to avoid the use of a solvent in the production of polymers. Environmental concerns as well as the need to produce residual solvent-free products for use in medical applications may necessitate the use of solvent-free reaction mixtures in polymerization reactions. It is known to form an acrylate polymer by free radical polymerization in the presence of a diluent such as toluene, hexane, pentane, acetone, methyl ethyl ketone, methanol, t-butyl alcohol, and isopropanol. See, for example, U.S. Pat. No. 4,619,979. However, it would be desirable to employ a diluent which can subsequently be incorporated into the resulting material by formation of either a graft copolymer, an interpolymer or blend.
OBJECTS AND SUMMARY OF THE PRESENT INVENTION
It is accordingly an object of the present invention to provide a novel method for the production of an acrylate polymer optionally in the absence of a solvent.
It is also another object, of the present invention to provide a novel method for the production of an acrylate polymer optionally in the absence of a solvent and which exhibits pressure sensitive adhesive properties.
It is also an object of the present invention to provide a blend of an acrylate polymer and a crosslinked diluent.
It is also an object of the present invention to provide an interpolymer formed by the method of the present invention.
It is further an object of the present invention to provide a graft copolymer formed by the method of the present invention.
In accordance with the present invention, there is thus provided a method for the production of an acrylate polymer in the presence of at least one liquid diluent comprising the steps of:
(1) providing a reaction mixture comprising at least one A monomer consisting of a monomeric (meth)acrylic acid ester of a non-tertiary alcohol together with said liquid diluent, optionally at least one B monomer different from said A monomer, optionally at least one polymeric graft moiety C having a T
g
greater than 20° C., and optionally at least one polymeric graft moiety D containing repeat hydrophilic units;
(2) forming an acrylate polymer in the presence of said diluent by free radical polymerization under conditions whereby the at least one diluent is non-reactive; and
(3) subsequently curing said diluent, and wherein said at least one diluent is selected from the group consisting of:
(a) a ring-opening monomer diluent producing a polymer having a T
g
<20° C., and
(b) mixtures of said ring-opening monomer diluent and a multifunctional liquid polymer having a T
g
<20° C.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is directed to a method for the production an acrylate. polymer in the presence of at least one liquid diluent, with the diluent subsequently being incorporated into the acrylate polymer product by subjecting the diluent to reactive conditions. By way of definition, the acrylate polymer initially formed by the method of the present invention may comprise a homo- or copolymer, and which may optionally include polymeric graft moieties. Preferably, the resulting polymer product exhibits pressure sensitive adhesive properties.
The initial acrylate polymer comprises the reaction product of at least one acrylate A monomer, optionally a B monomer different from said A monomer, optionally a polymeric graft moiety C having a T
g
greater than 20° C., and optionally a polymeric graft moiety D containing repeat hydrophilic units different from polymeric graft moiety C.
The at least one A monomer comprises a monomeric (meth)acrylic acid ester of a non-tertiary alcohol where the alcohol portion has from 1 to 30 carbon atoms. Exemplary A monomers include but are not limited to esters of acrylic acid or methacrylic acid with non-tertiary alcohols such as 1-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 1-methyl-1-pentanol, 2-methyl-1-penitanol, 3-methyl-1-pentanol, 2-ethyl-1-butanol, 3,5,5-trimethyl-1-hexanol, 3-heptanol, 2-octanol, 1-decanol, 1-dodecanol, etc. Exemplary A monomers formed from an alcohol having at least 12 carbon atoms include but are not limited to lauryl acrylate (C
12
), tridecylacrylate (C
13
), myristyl acrylate (C
14
), palmityl acrylate (C
16
) and stearyl acrylate (C
18
). Such monomers are well-known to those skilled in the art. The least one A monomer component (if more than one A monomer is present) will preferably exhibit an average number of carbon atoms in the alcohol portion of the total acrylic or (meth)acrylic acid esters of from 4 to 16.
One or more optional polymerizable B monomers different from the A monomer may be incorporated in the copolymer which B monomer(s) is copolymerizable with the A monomer. Such additional B monomer(s) may be either hydrophilic or hydrophobic.
Exemplary optional B monomers include vinyl monomers having at least one nitrogen atom. Such monomers (each of which exhibit a T
g
of >20° C.) include but are not limited to N-mono-substituted acrylamides such as acrylamide, methacrylamide, N-methylacrylamide, N-ethylacrylamide, N-methylolacrylamide, N-hydroxyethylacrylamide, and diacetone acrylamide; N,N-disubstituted acrylamides such as N,N-dimethylacrylamide, N,N-diethylacrylamide, N-ethyl-N-aminoethyl acrylamide, N-ethyl-N-hydroxyethylacrylamide, N,N-dimethylolacrylamide, and N,N-dihydroxyethylacrylamide, etc.
Other optional B monomers may include, for example, various vinyl monomers such as (meth)acrylic acid, itacoriic acid, crotonic acid, methoxyethyl (meth)acrylate, ethyoxyethyl (meth)acrylate, glycerol (meth)acrylate, hydroxyethyl methacrylate; hydroxypropyl methacrylate, beta-carboxyethyl acrylate, vinyl pyrrolidone, vinyl caprolactam and caprolactam acrylate. One or more B monomers may be employed. Hydroxy-containing B monomers if present provide reactive sites to assist in the crosslinking of or reaction between the acrylate polymer and the diluent during the curing step.
The optional graft polymeric moiety C has a T
g
greater than 20° C. Graft polymeric moiety C has the formula X—Z wherein X is a group copolymerizable with monomers A and B or capable of attachment to copolymerized A and B monomers and Z is a polymeric graft moiety having a T
g
greater than 20° C. The Z moiety is essentially unreactive under copolymerization conditions.
More specifically, the X moiety is an unsaturated polymerizable moiety the composition of which is not critical. The X moiety may, for example, when intended to be copolymerizable with monomers A and B, simply be a vinyl group of the formula CHR═CR
1
— where R is hydrogen or COOH and R
1
is hydrogen or alkyl such as methyl. Other exemplary X moieties include but are not limited to methacryloyl, maleoyl, itaconoyl, crotonoyl, unsaturated urethane moiety, methacrylamido and moieties of the formula CH
2
═CHCH
2
O—.
The X moiety may comprise an amine or alcohol moiety (such as a monohydroxyl or monoamine moiety) which permits attachment of the macromer to a suitable functionality on previously-polymerized monomers A and B. For instance, the hydroxyl moiety can serve as a terminal reactive group by reaction with suitable moieties on the polymer backbone resulting from the use of monomers such as isocyanate-substituted (meth)acrylic acid, (meth)acrylic acid anhydride, etc.
A variety of functional groups may be employed to attach the graft Z to the polymer backbone.
Exemplary functional groups include but are not limited to
and —OCH
2
CH
2
—O—CHR—CH
2
, where R is a hydrogen atom or a lower alkyl group.
With regard to the optional polymeric graft moiety C, U.S. Pat. Nos. 3,786,116; 3,842,057; 3,842,058; 3,842,059; 3,862,098; 3,862,101, 3,862,102 and 4,554,324 disclose polymerizable macromers which are suitable for use as graft moieties on a backbone polymer as defined.
Preferably, the polymeric moiety C is formed from a vinyl aromatic monomer such
Adhesives Research Inc.
Pezzuto Helen L.
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