Preparation of bromine-containing hydroxy-functional copolymers

Details Preparation of bromine-containing hydroxy-functional copolymers Preparation of bromine-containing hydroxy-functional copolymers

2001-03-27

2003-07-29

Truong, Duc (Department: 1711)

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

Synthetic resins

From carboxylic acid or derivative thereof

C528S355000, C528S358000, C525S415000, C525S413000, C525S416000

Reexamination Certificate

active

06600007

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to processes for the preparation of bromine-containing hydroxy-functional copolymers, and more specifically, to novel bromine-containing hydroxy-functional esters and polyesters. The invention further relates to the use of the bromine-containing hydroxy-functional copolymers, for example, for use as a reactive flame retardant and/or cross-linker, in urethane and non-urethane systems, including such materials as foams, coatings, adhesives, elastomers, paints, composites, and the like.
2. Description of the Related Art
Bromine-containing compounds are commonly used for the fire retardation in various polymeric materials. Fire retardants can be applied in two forms: as non-reactive additives or as co-polymerizable reactive reactants.
Generally, fire retardant additives that are non-reactive do not react with a crosslinkable polymeric matrix. Instead, the non-reactive additives are dissolved or dispersed in the crosslinked polymer matrix without chemical reaction with the polymer matrix. Because the fire retardant is not chemically bonded to the crosslinked polymer matrix, the fire retardant may migrate out from the crosslinked polymer network. Migration of the fire retardant out of the polymer diminishes or eliminates the influence that the fire retardant has on the crosslinked polymer matrix. In addition, the presence of the dissolved or dispersed fire retardant may detract from the physical properties of the polymer matrix.
A reactive fire retardant is one that reacts chemically with the other reactants, so that the fire retardant becomes permanently incorporated into the crosslinked polymer network and contributes to the overall properties of the final product.
Commonly used and commercially available reactive hydroxyl, bromine-containing fire retardants include the diester/ether diol of tetrabromophthalic anhydride, tetrabromobisphenol A-bis(2-hydroxyethyl ether), tetrabromobisphenol A (TBBPA), dibromoneopentyl glycol (DBNPG), tetrabromodipentaerythritol, 2,4-dibromophenol, 2,4,6-tribromophenol, dibromopropanol, tribromoneopentyl alcohol (TBNPA). (Encyclopedia of Chemical Technology, Vol. 10, pp. 930.)
TBBPA is the largest volume reactive flame retardant and its primary use is in epoxy resins. DBNPG has found particular application in unsaturated polyester resins and polyurethane foams, elastomers and coatings. The chemical structure of DBNPG confers to it a relatively high thermal stability and greatly contributes to its outstanding properties as a fire retardant.
One of the main disadvantages of DBNPG for polyurethanes is its limited solubility and slow dissolution rate in many of the raw materials commonly used for the preparation of polyurethane products. DBNPG is a crystalline solid (melting point (mp): 109.5° C.) and when solubilized, can react with the isocyanate component of the polyurethane formulations. For DBNPG to be used effectively in polyurethane formulations, DBNPG must be introduced and dissolved in the polyol component. However, most of the commercially available polyols, including polyester polyols and polyether polyols, show relatively low solubility for DBNPG. If DBNPG is not fully dissolved in the polyol components, several problems may result, such as poor physical and retardation properties as well as blockage of the lines and nozzles of polyurethane manufacturing equipment.
For highly fire resistant rated materials, it is often desirable to add twenty percent or more of the fire retardant DBNPG to the final product. The limited solubility of DBNPG in various polyether and polyester polyols gives DBNPG a significant disadvantage when used in many polyurethanes (e.g., foams, coatings, adhesives, elastomers) and non-polyurethane thermosets (e.g., coatings, paints, composites).
A number of proposals have been offered for overcoming this drawback of DBNPG. The Dow Chemical Company developed a liquid flame retardant based on DBNPG. This material, known under the trademark XNS-50044, is prepared by esterifying DBNPG (two moles) with adipic acid (one mole). The final liquid fire retardant is a hydroxyl terminated polyester polyol (D. P. Miller, Journal of Cellular Plastics, July/August 1979, pp. 211-219). However the disadvantage of this final product is cost. A further disadvantage of the adipate is its tendency to form a very viscous mass due to polyester formation.
A similar process is reportedly described in DD-A 2,166,942, where bromine-containing alcohol components are reacted with carboxylic acids to produce polyesters. However, the high viscosity of these products prevents them from being used in all polyurethane systems.
Another possibility is the process described in DD-A 207, 916 and U.S. Pat. No 4,394,306, in which bromine-containing polyols including DBNPG and dibromobutenediol react with formalin solution (35-38% of formaldehyde) to form polyoxymethylene hemi-formals through hydroxymethylation reaction. Hydroxymethylation between an alcohol and formaldehyde results in the substitution of the hydrogen atom of the alcoholic hydroxyl groups by —CH
2
—OH groups leading to a terminal hydroxyl group.
Further reaction with additional formaldehyde can occur to form high molecular weight polyoxymethylene hemi-formals. As described, this process can provide hydroxyl-terminal groups, which can be used as reactive groups for further use in polyurethanes (e.g., foams, coatings, adhesives, elastomers) and non-polyurethane thermosets (e.g., coatings, paints, composites). However, the reaction between alcohol and formaldehyde is difficult to control and usually causes an undesirable increase in the viscosity of the final reactive bromine-containing alcohol. In addition, segregation and incompatibilities can result when the resulting products are used in polyurethane systems.
U.S. Pat. No. 3,933,690 discloses the bromination of 2-butyne-1,4-diol to produce 2,3-dibromo-2-butene-1,4-diol, then the dibromobutenediol is blended with a variety of polyols including polyether and polyester polyols, and even propylene oxide for an alkoxylation reaction. However, this process leads to a darkly colored dibromobutenediol, and evolution of bromine. In addition, the final product is a mixture of bromine-containing and non-bromine-containing polyols.
GB-A 1,412,384 and EP-B 0,221,586 discloses the preparation of bromine-containing polyols by the reaction of butenediol or butynediol with epichlorohydrin and/or other alkylene oxides and bromination of the unsaturated polyols produced. However, this process produces polyols having a low content of bromine and low functionality. These polyols find use only in hard polyurethane foams at the expense of quality.
U.S. Pat. No. 3,474,148 discloses the preparation of bromine-containing monoalkyl ethers of trimethylolpropane or pentaerythritol by brominating the corresponding allyl ethers. However, the preparation of allyl ethers is a slow reaction and is difficult to control. In addition, the subsequent bromination produces a number of side reactions producing a large number of reaction products.
U.S. Pat. No. 3,948,860 discloses a process to liquefy dibromoneopentyl glycol, in which dibromoneopentyl glycol reacts with phosphoric anhydride to produce dibromoneopentyl glycol phosphoric acid ester, which is subjected to alkoxylation with epichlorohydrin and/or propylene oxide. The final product is phosphorus-halogen-containing flame retardant. However, the dark color of the final product limited its practical use in certain applications, for instance, where a clear or transparent coating is required.
U.S. Pat. No. 4,621,104 proposes a process for preparation of bromine-containing polyether polyols in which unsaturated diols such as butyne-1,4-diol polymerize with alkylene oxides such as ethylene oxide and propylene oxide to produce unsaturated polyether polyols. The unsaturated polyether polyols are then brominated. Disadvantageously, the final product is dark in color and the bromination yield is very low (no content of bromine available).
The use of dimethyl m

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