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
1999-04-13
2002-08-13
Wilson, D. R. (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...
C525S286000, C525S292000, C525S301000, C525S303000, C525S309000, C525S310000, C525S326500, C525S327300, C525S327500, C525S327700, C525S328800, C525S328900, C525S329400, C525S329500, C525S330100, C525S330200, C525S330600, C525S330700, C525S333100, C525S333200, C525S333300, C525S333500
Reexamination Certificate
active
06433098
ABSTRACT:
The present invention relates to a process of preparing curable compositions and compositions therefrom.
Oligomers, polymers with low Dp (degree of polymerization), of acrylate or methacrylate unit-containing backbones are of commercial interest and have industrial uses for many different applications, such as adhesives, inks, coatings, films, and others. A suitable low Dp value will provide a material with a molecular weight high enough for reduced toxicity, yet low enough for low viscosity. However, production of such oligomers has proven to be difficult and is frequently carried out by cumbersome and/or not very selective processes. It becomes even more difficult if a crosslinkable or curable oligomer composition is desired for the applications. This is because crosslinking or curing property typically requires the presence of additional reactive pendant groups in the oligomers. Such reactive pendant groups may be partially or substantially eliminated or reacted away by unintended side reactions or premature crosslinking reactions during the oligomerization reaction.
Several approaches have been tried and used to effect production of such oligomers. For example, one approach uses chain transfer agents to control Dp. As a result of the chain transfer chemistry involved, one chain transfer agent is incorporated into each backbone structure of the oligomers. This makes the oligomer property much less uniform and harder to control. In addition, the most commonly used chain transfer agents are mercaptans. Due to their odors and chemical properties, it becomes increasingly more difficult socially and less acceptable environmentally to use such sulfur-based materials. Other common chain transfer agents such as hypophosphites, bisulfites and alcohols would also impart additional functionalities into the oligomers. Such additional functionalities may not be compatible with other ingredients in a formulated product or suitable for the intended applications. Removal of the additional functionality from the resultant oligomers may be difficult and/or expensive.
Another approach calls for the use of large amounts of initiators or catalysts. This approach adds raw material cost to oligomer production. It also may result in undesirable oligomer chain degradations, branching, and unintended or premature crosslinking of the product prior to use. In addition, any residual initiators or catalysts in the product may have to be removed before the product can be used for many applications to avoid compatibility or contamination problems.
U.S. Pat. No. 4,356,288, discloses the preparation of terminally-unsaturated oligomers with a Dp in the range of from about 6 to about 30 from esters of acrylic acid by an anionic polymerization reaction carried out in the presence of a catalytic amount of an alkoxide anion. Alkoxide anions are known to be sensitive to water. Accordingly, the method is often adversely affected by the presence of moisture, resulting in lower yield and/or lower uniformity of the oligomer product.
Another patent, U.S. Pat. No. 5,710,227, discloses a high temperature, continuous polymerization process for preparing terminally unsaturated oligomers which are formed from acrylic acid and its salts, and acrylic acid and its salts with other ethylenically unsaturated monomers. The high temperature, continuous polymerization process solves many of the problems associated with previously known methods for preparing terminally-unsaturated oligomers formed from acrylic acid. However, the neat form of many of the acrylic acid products are solid at room temperature and, thus, requiring either heating and/or the addition of a solvent to handle and use the products.
U.S. Pat. No. 5,484,850 discloses copolymer compositions which are crosslinkable by a free radical method and have a Mn from 1500 to 6000 and a polydispersity of 1 to 4. Copolymer A is composed of from 50 to 85 mol % of a monomer (a1) containing methacryloyl group; from 15 mol % to 50 mol % of another monomer (a2) capable of undergoing free-radical polymerization; and from 5 mol % to 50 mol % of the total amount of the monomers (a1) and (a2) being monomers (a3) which carry functional groups selected from the group consisting of hydroxy, carboxyamido, amino, carbonyl, isocyanate, carboxyl and epoxy, the functional groups being capable of undergoing a condensation or addition reaction. The polymerization is carried out at a temperature from 140 to 210° C. and with an average residence time of from 2 minutes to 90 minutes. Copolymer A reacts with an olefinically unsaturated monomer B which carries a functional group which is complementary to the functional groups of monomers (a3). The products are solids which tend to limit their uses and processing options.
The present invention seeks to overcome the problems associated with the previously disclosed methods for preparing oligomers, particularly curable or crosslinkable liquid oligomers, by providing an oligomerization process that produces curable oligomers with a low Dp, in the range of from 3 to 100, without the need of excessive amounts of initiators. The curable oligomer products are in liquid form and may be terminally unsaturated. The crosslinkable or curable functionality is incorporated into the oligomer by a reaction after the oligomerization—a post-oligomerization reaction—between the oligomer or altered oligomer with a modifier which contains a crosslinkable/curable functional group. The present invention also provides curable oligomer compositions prepared according to the disclosed process. Furthermore, the invention provides curable oligomer compositions which are substantially free of metals, salts and/or surfactant contaminants. The product from the present invention is useful for a number of applications, such as films, markings, coatings, paints, adhesives, binders, inks and others.
More specifically, the present invention relates to a process of preparing a curable composition comprising forming an oligomer having a Dp in the range of from 3 to 100 from oligomerization of a mixture which comprises a monomer A and a monomer B under a first condition, wherein the monomer A has at least one functional group which either is generated after the oligomerization or is present in the monomer A before the oligomerization and remains substantially unreacted during the oligomerization; the oligomer has a first number of monomer units incorporated into its backbone; and wherein the first condition comprises a temperature in the range of from 150° C. to 650° C. and a pressure in the range of from 3 MPa to 35 MPa which is sufficient to maintain the mixture in a fluid state, and a residence time at the temperature and the pressure in the range of from 0.1 second to 4 minutes; and reacting a modifier having at least one reactive moiety with the oligomer through a reaction under a second condition between the reactive moiety of the modifier and the functional group of the monomer A incorporated into the oligomer to produce the curable composition, wherein the modifier further comprises a curable group selected from the group consisting of a carbon-carbon double bond, an oxygen-containing heterocyclic group and mixtures thereof, and the curable group remains pendant in the curable composition and crosslinkable after the reaction.
The term “oligomer” used herein means a polymer composition which has a degree of polymerization (Dp) in the range of from 3 to 100. Unless otherwise specified in the present application, the term “polymerization” is used herein as a generic term and interchangeably with the term “oligomerization.” An oligomer has a number of monomer units incorporated into the backbone. Dp is determined as a monomer unit average number. Depending on the oligomerization reaction mechanism, the actual number of carbon atoms in a particular oligomer backbone may be of an even or an odd number, even though the carbon-carbon double bonds in the monomers have two carbons each. Since it is rare that all of the oligomer molecules have the same total number of monomer units incorpo
Beckley Ronald Scott
Bowe Michael Damian
Brown Ward Thomas
Lange Barry Clifford
Merritt Richard Foster
Rohm and Haas Company
Wilson D. R.
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