Method of macromonomer synthesis

Details Method of macromonomer synthesis Method of macromonomer synthesis

1999-10-19

2002-04-23

Wu, David W. (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S208000, C526S212000, C526S213000, C526S220000, C526S319000, C526S291000, C526S306000, C526S303100, C526S332000, C526S227000

Reexamination Certificate

active

06376626

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to a free-radical polymerization process for the production of branched &ohgr;-unsaturated polymers (macromonomers) of general structure 1 based on monosubstituted vinyl monomers.
The synthesis of macromonomers based on monosubstituted monomers has previously been achieved by the use of addition-fragmentation chain transfer agents. For example, by polymerization of an acrylate monomer in the presence of an allyl sulfide chain transfer agent (Rizzardo et al,
Macomol. Symp.,
15 1996, 111, 1). The synthesis of macromonomers has also been achieved by copolymerization of a monosubstituted monomer with an alpha-methylvinyl monomer, e.g., a methacrylate monomer, in the presence of a cobalt catalytic chain transfer agent. See, for example, WO 9731030. The process of the current invention does not require added reagents other than the polymerization initiator.
Polymerizations of various monomers (in particular, acrylic monomers) have previously been performed where reaction conditions have been chosen to maximize conversion and control molecular weight. For example, U.S. Pat. No. 4,546,160 describes a process for synthesizing polymers based on acrylic and methacrylic monomers where reactions are carried out at high reaction temperatures to limit molecular weight. However, no attention was paid to the design of reaction conditions to optimize the macromonomer purity or the branch structure.
U.S. Pat. No. 5,710,227 describes a synthesis of macromonomers based on monomers of acrylic acid and its salts. The process is performed at high reaction temperatures (typically >225° C.) and does not describe the conditions necessary to control the purity of the macromonomer or the extent of branch formation. Furthermore, patentees report that macromonomer purity decreases as the polymerization temperature drops below 200° C. The process is further restricted to polymers containing monomers of acrylic acid and its salts.
In conventional practice, when polymerizations are carried out at high reaction temperatures, these are typically carried out under conditions where there is a high flux of initiator-derived radicals. These conditions are unsuited for high purity macromonomer synthesis. The process disclosed herein sets out guidelines whereby the molecular weight of the macromonomer and the degree of branching in the macromonomer can be controlled. In the process described herein high purity (>90%) macromonomers are prepared at any polymerization temperature including temperatures below 100° C. The process described herein can be applied to the preparation of &ohgr;-unsaturated homopolymers of acrylates, styrene and vinyl esters. Furthermore, the process discloses guidelines for the preparation of high purity &ohgr;-unsaturated random copolymers based on one or more monosubstituted vinyl monomers or based on one or more alpha-substituted vinyl monomers.
SUMMARY OF THE INVENTION
This invention is directed to a process for the synthesis of polymers of the general formula (1):
comprising
(A) contacting:
(a) CH
2
═CHY;
(b) optionally, CH
2
═CXB;
(c) free radicals, produced from a free radical source;
wherein:
X is independently selected from the group consisting of halogen, or optionally substituted C
1
-C
4
alkyl wherein the substituents are independently selected from the group consisting of hydroxy, alkoxy or aryloxy (OR), carboxy, acyloxy or aroyloxy (O
2
CR), alkoxy- or aryloxy-carbonyl (CO
2
R);
Y is independently selected from the group consisting of R, CO
2
H, CO
2
R, COR, CN, CONH
2
, CONHR, CONR
2
, O
2
CR, OR or halogen;
B is selected from the group consisting of R, CO
2
H, CO
2
R, COR, CN, CONH
2
, CONHR, CONR
2
, O
2
CR, OR, halogen or a polymer chain;
R is selected from the group consisting of optionally substituted C
1
-C
18
alkyl, C
2
-C
18
alkenyl, aryl, heterocyclyl, aralkyl, alkaryl wherein the substituents are independently selected from the group that consists of epoxy, hydroxy, alkoxy, acyl, acyloxy, carboxy (and salts), sulfonic acid (and salts), alkoxy- or aryloxy-carbonyl, isocyanato, cyano, silyl, halo, and dialkylamino;
Z is selected from the group consisting of H and a free radical initiator-derived fragment of optionally substituted alkyl, cycloalkyl, aryl, aralkyl, alkaryl, organosilyl, alkoxyalkyl, alkoxyaryl, hydroxy, hydroperoxy, alkylperoxy, alkoxy, aroyloxy groups wherein substituent(s) are selected from R, OR, O
2
CR, halogen, CO
2
H (and salts), CO
2
R, CN, CONH
2
, CONHR, CONR
2
, sulfate,
m≧1;
n≧0;
p≧0;
and when one or both of m and n are greater than 1, the repeat units are the same or different;
the [CH
2
—CUY]
p
moiety contains branch point, U, and is derived from structure (1) whereby U is of random structure (2):
(B) controlling polymer quality by adjusting the following variables:
(i) increasing the proportion of vinyl terminated polymer by increasing the molar ratio of (a)/(b);
(ii) increasing the proportion of vinyl terminated polymer by decreasing the molar ratio of (c)[(a)+(b)];
(iii) controlling the degree of branching (value of p) as follows:
(d) decreasing p by increasing temperature;
(e) decreasing p by decreasing monomer concentration;
(f) increasing p by increasing conversion;
(iv) controlling the molecular weight of the polymer as follows:
(g) decreasing molecular weight by decreasing monomer concentration; and
(h) decreasing molecular weight by increasing temperature.
The preferred proportion of vinyl terminated polymer is ≧50 percent, more preferably, greater than 70 percent. The preferred degree of branching is, on average, ≦10 branches per chain. The preferred degree of polymerization (m+n+p) is from 1 to about 500.
DETAILS OF THE INVENTION
We have found that macromonomers (1) can be synthesized by conducting a polymerization of monosubstituted monomer(s) with appropriate choice of reaction conditions. Monomers CH
2
═CHY and CH
2
═CXB are polymerizable or copolymerizable monomers. As one skilled in the art would recognize, the choice of monomers is determined by their steric and electronic properties. The factors which determine polymerizability and copolymerizability of various monomers are well documented in the art. For example, see: Greenley, in Polymer Handbook 3rd Edition (Brandup and Immergut, Eds.) Wiley, N.Y., 1989 p II/53.
Preferred monosubstituted monomers (CH
2
═CHY) are one or more of the following: methyl acrylate, ethyl acrylate, propyl acrylate (all isomers), butyl acrylate (all isomers), 2-ethylhexyl acrylate, isobornyl acrylate, acrylic acid, benzyl acrylate, phenyl acrylate, acrylonitrile, styrene, functional acrylates selected from glycidyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate (all isomers), hydroxybutyl acrylate (all isomers), diethylaminoethyl acry late, triethyleneglycol acrylate, N-tert-butyl acrylamide, N-n-butyl acrylamide, N-methylol acrylamide, N-ethylol acrylamide, vinyl benzoic acid (all isomers), diethylamino styrene (all isomers), p-vinyl benzene sulfonic acid, trimethoxysilylpropyl acrylate, triethoxysilylpropyl acrylate, tributoxysilylpropyl acrylate, dimethoxymethylsilylpropyl acrylate, diethoxymethylsilylpropyl acrylate, dibutoxymethylsilylpropyl acrylate, diisopropoxymethylsilylpropyl acrylate, dimethoxysilylpropyl acrylate, diethoxysilylpropyl acrylate, dibutoxysilylpropyl acrylate, diisopropoxysilylpropyl acrylate, vinyl acetate, and vinyl butyrate, vinyl chloride, vinyl fluoride, vinyl bromide and propene.
Preferred disubstituted monomers CH
2
═CXB are one or more of the following: methyl methacrylate, ethyl methacrylate, propyl methacrylate (all isomers), butyl methacrylate (all isomers), 2-ethylhexyl methacrylate, isobornyl methacrylate, methacrylic acid, benzyl methacrylate, phenyl methacrylate, methacrylonitrile, glycidyl methacrylate,
2
-hydroxyethyl methacrylate, hydroxypropyl methacrylate (all isomers), hydroxybutyl methacrylate (all isomers), diethylaminoethyl methacrylate, triethyleneglycol methacrylate, trimethoxysilylpropyl met

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