Paper making and fiber liberation – Processes and products – Non-fiber additive
Reexamination Certificate
2000-06-12
2003-04-29
Buttner, David J. (Department: 1712)
Paper making and fiber liberation
Processes and products
Non-fiber additive
C162S164600, C524S017000, C524S422000, C524S608000, C435S262000, C528S486000, C528S487000
Reexamination Certificate
active
06554961
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to polyamine-epihalohydrin resin products, particularly polyamine-epihalohydrin resin products which can be stored with at least reduced formation of halogen containing residuals, such as 3-chloropropanediol (CPD). Moreover, the present invention relates to formation of polyamine-epihalohydrin resins having at least reduced formation of halogen containing residuals, and to various uses of the resins, such as wet strength agents. More specifically, the present invention relates to polyamine-epihalohydrin resin products which have reduced levels of formation of CPD upon storage, such as paper products. Moreover, the present invention relates to the production of polyamine-epihalohydrin resins prepared from polyaminoamide prepolymers containing low levels of acid functionalities, and to resins formed thereby.
2. Discussion of Background Information
Polyamine-epihalohydrin resins, such as polyaminopolyamide-epihalohydrin resins are cationic thermosetting materials used to increase the wet strength of papers. Often these materials contain large quantities of epihalohydrin hydrolysis products. For example, commercial polyaminopolyamide-epichlorohydrin resins typically contain 1-10 wt % (dry basis) of the epichlorohydrin (epi) by-products, 1,3-dichloropropanol (1,3-DCP), 2,3-dichloropropanol (2,3-DCP) and 3-chloropropanediol (CPD). Production of wet-strength resins with reduced levels of epi by-products has been the subject of much investigation. Environmental pressures to produce wet-strength resins with lower levels of adsorbable organic halogen (AOX) species have been increasing. “AOX” refers to the adsorbable organic halogen content of the wet strength resin which can be determined by means of adsorption onto carbon. AOX includes epichlorohydrin (epi) and epi by-products (1,3-dichloropropanol, 2,3-dichloropropanol and 3-chloropropanediol) as well as organic halogen bound to the polymer backbone.
Commercial papermaking operations typically utilize paper wet strengthening formulations which comprise cationic thermosetting polymers. In the papermaking process, waste material is frequently disposed of in landfills, etc. It is desirable to reduce the organohalogen content of such wastes to as low a level as possible. This waste is a substantially solid mass of material which is exposed to the environment. The exposure of the waste to the environment results in the selection of microorganisms which feed on the components in the waste. It is known that there are microorganisms which feed on the organohalogen compounds in the solid waste.
In the papermaking process the epichlorohydrin hydrolysis products are released into the environment in the water used to make paper, or into the air by evaporation during the paper drying step, or into the paper itself or a combination of these events. It is desirable to reduce and control these emissions into the environment to as low a level as possible. Reduced levels of CPD are especially desirable in applications where food is the end use.
Several ways of reducing the quantities of epihalohydrin hydrolysis products have been devised. Reduction in the quantity of epihalohydrin used in the synthetic step is an alternative taught in U.S. Pat. No. 5,171,795. A longer reaction time results. Control over the manufacturing process is taught in U.S. Pat. No. 5,017,642 to yield compositions of reduced concentration of hydrolysis products. These patents are incorporated by reference in their entireties.
Post-synthesis treatments are also taught. U.S. Pat. No. 5,256,727, which is incorporated by reference in its entirety, teaches that reacting the epihalohydrin and its hydrolysis products with dibasic phosphate salts or alkanolamines in equimolar proportions converts the chlorinated organic compounds into non-chlorinated species. To do this it is necessary to conduct a second reaction step for at least 3 hours, which adds significantly to costs and generates quantities of unwanted organic materials in the wet strength composition. In compositions containing large amounts of epihalohydrin and epihalohydrin hydrolysis products (e.g., about 1-6% by weight of the composition), the amount of organic material formed is likewise present in undesirably large amounts.
U.S. Pat. No. 5,516,885 and WO 92/22601, which are incorporated by reference in their entireties, disclose that halogenated by-products can be removed from products containing high levels of halogenated by-products as well as low levels of halogenated by-products the use of ion exchange resins. However, it is clear from the data presented that there are significant yield losses in wet strength composition and a reduction in wet strength effectiveness.
It is known that nitrogen-free organohalogen-containing compounds can be converted to a relatively harmless substance. For example, 1,3-dichloro-2-propanol, 3-chloro-1,2-propanediol (also known as 3-chloropropanediol, 3-monochloropropanediol, monochloropropanediol, chloropropanediol, CPD, 3-CPD, MCPD and 3-MCPD) and epichlorohydrin have been treated with alkali to produce glycerol.
The conversion of nitrogen-free organohalogen compounds with microorganisms containing a dehalogenase is also known. For example, C. E. Castro, et al. (“Biological Cleavage of Carbon-Halogen Bonds Metabolism of 3-Bromopropanol by Pseudomonas sp.”,
Biochimica et Biophysica Acta,
100, 384-392, 1965), which is incorporated by reference in its entirety, describes the use of Pseudomonas sp. isolated from soil that metabolizes 3-bromopropanol in sequence to 3-bromopropionic acid, 3-hydroxypropionic acid and CO
2
.
Various U.S. patents also describe the use of microorganisms for dehalogenating halohydrins, e.g., U.S. Pat. Nos. 4,452,894; 4,477,570; and 4,493,895. Each of these patents is hereby incorporated by reference as though set forth in full herein.
U.S. Pat. Nos. 5,470,742, 5,843,763and 5,871,616, which are incorporated by reference in their entireties, disclose the use of microorganisms or enzymes derived from microorganisms to remove epihalohydrin and epihalohydrin hydrolysis products from wet strength compositions without reduction in wet strength effectiveness. Processes of removal are described which remove up to 2.6 weight per cent of halogenated by-product based on the weight of the composition. The amount of microorganism or enzyme used is in direct proportion to the quantity of halogenated by-product present. Thus, when present in large quantities (e.g., more than about 1% by weight of the composition) a large proportion of microorganism or enzyme is needed to adequately remove the unwanted product. Large quantities of halogenated byproduct can be toxic to the microbes employed in such dehalogenation processes. Each of these documents is hereby incorporated by reference as though set forth in full herein.
Still further, U.S. application Ser. No. 08/482,398, now U.S. Pat. No. 5,972,691 and WO 96/40967, which are incorporated by reference in their entireties, disclose the treatment of wet strength compositions with an inorganic base after the synthesis step (i.e., after the polymerization reaction to form the resin) has been completed and the resin has been stabilized at low pH, to reduce the organo halogen content of wet strength compositions (e.g., chlorinated hydrolysis products) to moderate levels (e.g., about 0.5% based on the weight of the composition). The composition so formed can then be treated with microorganisms or enzymes to economically produce wet strength compositions with very low levels of epihalohydrins and epihalohydrin hydrolysis products.
It is also known that epihalohydrin and epihalohydrin hydrolyzates can be reacted with bases to form chloride ion and polyhydric alcohols. U.S. Pat. No. 4,975,499 teaches the use of bases during the synthetic step to reduce organo chlorine contents of wet strength composition to moderate levels (e.g., to moderate levels of from about 0.11 to about 0.16%) based on the weight of the composition. U.S. Pat. No. 5,019,606 teaches react
Allen Anthony J.
Busink Ronald
Carlin, Jr. Francis J.
Cheng Huai Nan
Crisp Mark T.
Buttner David J.
Hercules Incorporated
Rossi Joanne
Samuels Gary A.
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