Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-11-27
2004-04-06
Rotman, Alan L. (Department: 1625)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S591000, C528S272000, C528S300000, C528S307000
Reexamination Certificate
active
06716913
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to monomers for use in the synthesis of polyurethanes, and more particularly to carboxyl-containing monomers made from a low molecular weight polyol compound and an acid anhydride, and in the presence of 5-500 ppm phosphoric acid.
2. Description of the Related Art
It is well known that polyurethanes are generally manufactured by reacting a polyisocyanate and a polyol. The produced polyurethane may have unique chemical and/or mechanical properties depending on the reacting conditions, as well as other additives such as catalysts, solvents, surfactants, blowing agents, fillers, and the like. The polyols used in manufacturing polyurethanes are typically low molecular weight poly-hydroxyl-containing polymers, such as those containing polyethers, polyesters, polyacrylics, polycarbonates, and the like. These polyols are generally provided with at least two hydroxyl groups so that they can be easily incorporated into a lengthening polymer in an ordered fashion.
Due to environmental and toxicity concerns, water-based polyurethanes and aqueous dispersions of polyurethanes are becoming the materials of choice for many applications, including aqueous applications. However, in many instances, the components of the polyurethane product are not easily soluble in water. To overcome this problem, it is known to introduce ionizable groups into the monomers prior to their condensation into the final polyurethane polymer. These ionizable groups are thought to aid in the solubilization of the polymer and thus produce a uniform aqueous dispersion of the final polyurethane mixture.
The reaction of succinic anhydride with triols or tetrols has been described generally in U.S. Pat. No. 5,863,980 to Kuen-Bae Choi. According to the disclosure, acid groups are introduced in the main chain in the absence of catalysts, including acid catalysts. In order to perform reaction between succinic anhydride and polyol, high reaction temperature was used and resulted in highly viscous polyols. When such highly viscous polyol was reacted with diisocyanate, a viscous prepolymer was obtained.
U.S. Pat. No. 4,207,2267 to Wulf von Bovin discloses a process for preparation of stable suspensions of inorganic fillers in poly-hydroxyl compounds by grafting olefinically unsaturated carboxylic acid onto polyol. As an example, acrylic acid and peroxide type initiators are used for this process.
U.S. Pat. No. 4,250,077 to Wulf von Bovin et al. discloses a suspension which is stable and contains inorganic filler and graft polymer which was produced by free radical polymerization of olefinically unsaturated carboxylic acid.
U.S. Pat. No. 4,460,738 to Frentzel et al. discloses a process for grafting carboxyl groups to mono and polyether polyols by reacting maleic acid, fumaric acid, itaconic acid or their mixtures with polyether polyols in presence of peroxy-type free radical initiator.
U.S. Pat. No. 4,521,615 to Frentzel et al. discloses a process for grafting carboxyl groups to mono and polyether polyol by reacting maleic acid, fumaric acid or their mixtures with short chain polyether polyols in presence of peroxy-type free radical initiator.
U.S. Pat. No. 5,990,250 to Housel et al. discloses a process for incorporating carboxyl groups into main polyester chain by reacting polyether or polyester polyol with aliphatic dianhydride.
U.S. Pat. Nos. 5,242,954 and 5,250,582 to Hire et al. disclose a process for making cellular and microcellular polyurethane foams using a carboxylic acid-grafted polyol.
A common result of introduction of a carboxyl group into the polyol component is undesirable side reactions between the carboxyl group and nearby hydroxyl groups. The side reactions markedly increases viscosity of the monomer mixture, and provides fewer usable monomers for incorporation into the final aqueous urethane dispersion. In addition, the reacted carboxyl group results in reduced hydrophilicity of the final urethane dispersion.
Accordingly, there is a need in the art for water-soluble monomers to be incorporated into a urethane dispersion that possesses low viscosity, and does not undergo undesirable side reactions. The present invention is believed to be an answer to that need.
SUMMARY OF THE INVENTION
In one aspect, the present invention is directed to carboxyl-containing monomers for use in preparing a polyurethane polymer, the carboxyl-containing monomer being the reaction product of a low molecular weight polyol compound and an acid anhydride in the presence of 5-500 ppm phosphoric acid, the carboxyl-containing monomer having a viscosity in the range of about 3,000-100,000 centipoise, and having free oligomer content in the range of about 2-30 mg KOH/g.
In another aspect, the present invention is directed to a method of preparing a carboxyl-containing monomer for use in preparation of a polyurethane polymer, comprising the step of combining a low molecular weight polyol compound and an acid anhydride in the presence of 5-500 ppm phosphoric acid to produce the carboxyl-containing monomer, the carboxyl-containing monomer having a viscosity in the range of about 3,000 to about 100,000 cps and having a free oligomer content in the range of about 2 to about 30 mg KOH/g.
In another aspect, the present invention is directed to a prepolymer for use in preparing a polurethane polymer, the prepolymer being the reaction product of (1) the carboxyl-containing monomer described above, and (2) a polyisocyanate compound, the prepolymer having a viscosity in the range of about 3,000 to about 100,000 cps.
In another aspect, the present invention is directed to a method of preparing a prepolymer for use in preparation of a polyurethane polymer, comprising the step of combining the prepolymer described above with a polyisocyanate compound to produce the prepolymer, the prepolymer having a viscosity in the range of about 3,000 to about 100,000 cps.
In another aspect, the present invention is directed to a water-borne polyurethane polymer, the water-borne polyurethane polymer being the reaction product of (1) the prepolymer of described above, and (2) an amine compound.
These and other aspects will become apparent upon reading the following detailed description of the invention.
DETAILED DESCRIPTION OF THE INVENTION
It has been surprisingly found, in accordance with the present invention, that a carboxyl-containing monomer being the reaction product of a low molecular weight polyol compound and an acid anhydride, and made in the presence of phosphoric acid, results in a chemical monomer that is very beneficial for making waterborne polyurethane dispersions. The present inventors have unexpectedly discovered that phosphoric acid is very efficient in catalyzing polyol-anhydride addition reactions with anhydride ring opening mechanism, while exhibiting little or no acceleration of acid and polyol condensation side reactions.
In contrast to the prior art where the hydroxyl groups of polyol are reacted with polyisocyanate to produce polyurethane prepolymer, the monomer made according to the present invention possesses an polar center (by virtue of the grafted carboxyl function) that is thought to stabilize and solvate waterborne polyurethane emulsions when polyurethane prepolymer is dispersed in a water or alkaline-water solution. In addition, the presence of phosphoric acid in the reaction medium is thought to maintain the grafted carboxyl group in a protonated state and thus prevent it from participating in undesirable side reactions which lead to a high viscosity product that has limited usefulness.
The present invention provides a process for “grafting” carboxyl groups to polyol monomers, and the low-viscosity carboxyl-containing polyol monomers made by the process. The term “grafting” refers to addition of one molecule onto another molecule by means of a chemical reaction. The process of the present invention generally consists of reacting a polyol monomer, preferably containing three hydroxyl groups per molecule, with an organic acid anhydride under condition
Gruzins Indulis
Hire Robert C.
McElheney Donald Farrell
Necessary Jerry Douglas
Arch Chemicals Inc.
Carlson Dale Lynn
Garabedian Todd E.
Oh Taylor V
Rotman Alan L.
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