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
2001-09-27
2003-07-01
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S276000, C525S199000, C525S280000, C525S331200, C525S326200, C525S254000, C525S326500, C525S294000, C525S295000, C526S169000, C526S170000, C526S171000, C526S172000
Reexamination Certificate
active
06586530
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to novel low surface tension (meth)acrylate containing block (co)polymer compositions prepared by a controlled radical (co)polymerization process, as well as a controlled radical (co)polymerization process to produce the low surface tension (meth)acrylate containing block copolymers.
BACKGROUND OF THE INVENTION
Fluorocarbon containing copolymers have been used as binding agents, wetting agents, surfactants and coating additives in a variety of applications. The fluorocarbon has the potential of providing a surface tension lowering effect. Fluorocarbon containing copolymers made by conventional free radical polymerization methods have inevitable shortcomings as it is difficult to control their molecular weight distribution and composition in order to optimize their desired physical properties. For example, the common problem of poor control of molecular weight distribution can result in a high molecular weight “tail”, which can give poor flow properties due to the high viscosity that results. Conversely, poor binding properties can result when too much of a low molecular weight “tail” is present.
U.S. Pat. Nos. 5,397,669 and 5,283,148 disclose an electrostatic liquid toner imaging process that uses a liquid toner comprised of a perfluorinated solvent and a polymer containing highly fluorinated units. The polymer was prepared using traditional free radical polymerization techniques and was characterized as having a polydispersity of 4.
U.S. Pat. No. 3,407,247 discloses fluoro olefin block copolymers prepared by traditional free radical polymerization of a (meth)acrylic monomer to form a prepolymer which is subsequently reacted with a fluoro olefin. While block copolymers were formed to some extent, the resulting block copolymers inherently vary widely in block length and molecular weight leading to a wide compositional variation and distribution as well as a large polydispersity.
U.S. Pat. No. 5,026,621 discloses a toner for electrophotography which includes a block copolymer binder resin comprised of a fluoroalkyl acryl ester block and a fluorine-free vinyl or olefin monomer block. The block copolymers were made using a unique peroxypolyether initiator, which is then used to initiate a first free radical polymerization, forming a peroxypolymer, which initiates a second free radical polymerization. While block copolymers are formed, the resulting block copolymers inherently vary widely in block length and molecular weight, as well as having a wide compositional variation, wide polymer composition distribution and a large polydispersity.
U.S. Pat. No. 5,478,886 discloses alkyl &agr;-fluoroacrylate ester block copolymers prepared by group transfer polymerization techniques. The block copolymers have a polydispersity of less than 2 and do not contain any initiator residue. The disclosure is limited to fluoroacrylate monomers as the fluorocarbon monomer. These types of block copolymers are used, primarily in the electronics industry as photoresists. The block copolymers are particularly subject to photodegradation and provide minimal surface tension lowering properties.
U.S. Pat. Nos. 5,629,372; 5,705,276; and 5,914,384 disclose coating compositions comprising an alkyl (meth)acrylate/fluoroalkyl methacrylate random copolymer and a crosslinking agent. The materials disclosed were suggested for use as clear coating compositions for application over a pigmented base coat. However, minimal surface tension lowering effect is provided because the fluoroalkyl methacrylate is randomly distributed along the polymer.
The use of conventional, i.e., non-living or free-radical (co)polymerization methods to synthesize (co)polymers provides little control over molecular weight, molecular weight distribution and, in particular, (co)polymer chain structure.
U.S. Pat. Nos. 5,807,937, 5,789,487 and 5,763,548, and International Patent Publication Nos. WO 98/40415, WO 98/01480, WO 97/18247 and WO 96/30421 describe a radical polymerization process referred to as atom transfer radical polymerization (ATRP). The ATRP process is described as being a living radical polymerization that results in the formation of polymers having predictable molecular weight and molecular weight distribution. The ATRP process also is described as providing highly uniform products having controlled structure (i.e., controllable topology, composition, etc.). The '937 and '548 patents also describe (co)polymers prepared by ATRP, which are useful in a wide variety of applications including, for example, dispersants and surfactants.
A number of initiators and macroinitiator systems are known to support ATRP polymerization. These initiators are described, for example, in U.S. Pat. Nos. 5,807,937 and 5,986,015. U.S. Pat. No. 5,807,937 discloses a number of initiators, including halide groups attached to a primary carbon. Halides attached to primary carbons are known as efficient initiators in ATRP processes. U.S. Pat. No. 5,986,015 discloses polymer macroinitiators prepared from vinyl chloride and another monomer, and their use in preparing graft (co)polymers with low polydispersity.
It also is desirable to have multiple initiation sites on an initiator in order to create unique branched (co)polymer structures, such as star (co)polymers. Such (co)polymers have a variety of practical applications, including use as a resin component of a film-forming coating composition. These unique (co)polymers also will find use in the health care or cosmetics industries for instance, as materials for bioengineering. (Co)polymers of low polydispersity (Mn/Mw) are also desirable not only for their structural regularity and related usefulness in producing defined block and multiblock (co)polymer structures, but for their unique physical characteristics. For instance, a star (co)polymer having low polydispersity is a high molecular weight material having low viscosity in solution.
There remains a need for polymers that have reliable compositions and predictable surface tension lowering effects. Such polymers can overcome the deficiencies of the fluorocarbon copolymers of the prior art.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a block copolymer that includes a first block made up of residues of a first low surface tension (meth)acrylate monomer, a second block containing residues of a second radically polymerizable ethylenically unsaturated monomer that is free of hydroxyl groups and amine groups, and, optionally, a third block containing residues of a third radically polymerizable ethylenically unsaturated monomer that is free of hydroxyl groups and amine groups. The first, second and third blocks are made of different residues from each other. The block copolymer is prepared by controlled radical polymerization and has a has a polydispersity index of less than 2.5.
The present invention is also directed to a method of making a low surface tension (meth)acrylate containing block copolymer using atom transfer radical polymerization (ATRP). The method includes the steps of sequentially adding a first monomer composition, which includes a first radically polymerizable low surface tension (meth)acrylate monomer, and a second monomer composition, which includes one or more radically polymerizable ethylenically unsaturated monomers that are free of hydroxyl groups and amine groups, to a suitable ATRP initiator having at least one radically transferable group to form a living block copolymer; where said first monomer composition and second monomer composition are different from each other. The sequence of addition of the low surface tension (meth)acrylate monomer and the second monomer will vary depending on the exact polymer composition desired.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Other than in the operating examples, or where otherwise indicated, all numbers or expressions referring to quantities of ingredients, reaction conditions, etc, used in the specification and claims are to be understood as modified in all instances by the term “a
Barkac Karen A.
Coca Simion
Goetz Jonathan D.
Humbert Kurt A.
Schimmel Karl F.
Asinovsky Olga
PPG Industries Ohio Inc.
Seidleck James J.
Uhl William J.
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