Dehalogenation of polyamine, neutral curing wet strength resins

Procedure for making polyamine-epihalohydrin resin products using very low levels of epihalohydrin or epihalohydrin hydrolyzates, especially helpful in papermaking, which includes, amongst other features, producing a polyamine-epihalohydrin plastic in aqueous solution, terminating the reaction by coolingsystem, adjusting the pH of this polyamine-epihalohydrin solution to from about 7.5 to about 11 and concurrently heating the solution to approximately 35 to about 50. degree. C., and contacting the aqueous solution with bacteria that are selected or an enzyme, and deactivating or removing the microbes or enzymes, cooling to approximately 20. degree. C. and stabilizing the makeup by adjusting the pH to approximately 2.0 to 5.0 by the addition of acid.


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1. Field of the Invention

The present invention relates to a process for producing polyamine-epihalohydrin resin products having very low levels of residual epihalohydrin hydrolyzates with very large wet strength efficacy.

2. Background and Material Information

Polyamine-epihalohydrin resins are cationic thermosetting materials used to increase the wet strength of papers. Often these materials contain large quantities of epihalohydrin hydrolysis products arising from the synthetic step (i.e., thereaction to generate the resin).

Commercial papermaking operations utilize paper moist strengthening formulations that include such cationic thermosetting polymers. In the papermaking process, waste substance is often disposed of in landfills, etc.. It’s desired to reducethe organohalogen content of these wastes to as low a level as you can. This waste is a considerably solid mass of substance which is exposed to the environment. The vulnerability of the waste to the environment results in the selection of microorganismswhich feed on the elements from the waste. It’s understood that there are microorganisms which feed on the organohalogen compounds in the solid waste.

In the papermaking process the epichlorohydrin hydrolysis products arising in the artificial step in the production of polyamine-epichlorohydrin resins, are discharged into the environment in the water used to make paper, or into the atmosphere byevaporation through the newspaper drying step, or into the paper itself or even a combination of these events. It is desirable to decrease and control these emissions into the environment to as low a level as you can.

Wet power compositions which contain large quantities of epihalohydrin and/or epihalohydrin hydrolysis products display high wet strength efficacy when compared with similar products made using diminished or low quantities of epihalohydrin.Thus, there’s a need to retain high wet strength efficacy but also to reduce substantially the large quantities of undesirable halogenated by-products from the wet strength makeup.

Several ways of decreasing the amounts of epihalohydrin hydrolysis products have been devised. Reduction in the quantity of epihalohydrin used in the synthetic step is an alternative educated in U.S. Pat. No. 5,171,795. A longer reaction timeresults. Control over the manufacturing method is educated in U.S. Pat. No. 5,017,642 to yield compositions of decreased concentration of hydrolysis products.

Decrease in the amount of epihalohydrin used is successful in cutting epihalohydrin and epihalohydrin hydrolysis products in the wet strength composition but has the undesirable side effect of reducing moist strength performance in proportion tothe decrease in epihalohydrin used. Thus, conventional wisdom dictates that decrease in the sum of epihalohydrin used in the polymerization reaction is to be averted or high wet strength effectiveness of these resins will besacrificed.

Post-synthetic treatments might be used. U.S. Pat. No. 5,256,727 teaches that reacting the epihalohydrin and its hydrolysis products with dibasic phosphate salts or alkanolamines in equimolar proportions extends the chlorinated organiccompounds to non-chlorinated species. To do this it is required to conduct another reaction step for at least 3 hours, which adds considerably to costs and generates amounts of undesirable organic substances in the wet strength composition. Incompositions comprising large amounts of epihalohydrin and epihalohydrin hydrolysis products (e.g., about 1-6% by weight of the article ), the quantity of organic material formed is similarly present in undesirably large quantities.

WO 92/22601 teaches that halogenated by-products can be removed from products containing elevated levels of halogenated by-products as well as low levels of halogenated by-products by the use of ion exchange resins. But, it’s clear from thedata demonstrated that there are considerable yield declines in wet strength composition along with a decrease in moist strength effectiveness.

It is understood that nitrogen-free organohalogen-containing compounds can be converted to a relatively benign substance. By way of example, 1,3-dichloro-2-propanol, 1-chloro-2,3-propanediol, and epichlorohydrin are treated with alkali to produceglycerol.

The conversion of nitrogen-free organohalogen substances with germs containing a dehalogenase can also be understood. For example, C. E. Castro, et al. (“Biological Cleavage of Carbon-Halogen Bonds Metabolism of 3-Bromopropanol by Pseudomonassp.” , Biochimica et Biophysica Acta, 100, 384-392, 1965) explain the usage of Pseudomonas sp. Isolated from soil that metabolizes 3-bromopropanol in order to 3-bromopropionic acid, 3-hydroxypropionic acid and CO.sub.2.

Various U.S. Patents also describe using microorganisms for dehalogenating halohydrins, e.g., U.S. Pat. Nos. 4,452,894; 4,477,570; and 4,493,895. All these patents is hereby incorporated by reference as though set forth in fullherein.

EP-A-0 510 987 A1 educates using microorganisms or enzymes derived from microorganisms to eliminate epihalohydrin and epihalohydrin hydrolysis products from moist power compositions without reduction in wet power effectiveness. Processes ofremoval are described which remove up to 2.6 pounds per cent of halogenated by-product based on the weight of the article. The amount of microorganism or enzyme used is in direct ratio to the amount of halogenated by-product present. Therefore,when present in large quantities (e.g., more than about 1 percent by weight of the article ) a sizable proportion of microorganism or enzyme is needed to adequately remove the unwanted product. Large quantities of halogenated byproduct can be toxic to themicrobes utilized in these dehalogenation processes. EP-A-0 510 987 A1 is a family member of all U.S. patent application Ser. No. 08/243,492, filed May 16, 1994, currently U.S. Pat. No. 5,470,742 which can be both a continuation of U.S. patent program Ser.No. 07/866,216, filed Nov.. 9, 1992, and a continuation-in-part of all U.S. patent application Ser. No. 07/690,765, filed Apr.. 9, 1992. Each one of these files is hereby incorporated by reference as if set forth in full herein.

It is also known that epihalohydrin and epihalohydrin hydrolyzates can be reacted with foundations to form chloride ion and polyhydric alcohols. U.S. Pat. No. 4,975,499 educates the use of bases during the synthetic step to reduce organo chlorinecontents of wet strength composition to moderate levels (e.g., to moderate heights of about 0.11 to about 0.16%) dependent on the weight of the composition. U.S. Pat. No. 5,019,606 teaches reacting wet strength compositions with a natural orinorganic base.

Each of the foregoing approaches has provided less than optimal results, and there’s been a continuous need for advancement.

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