| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | April 29, 2003 |
| PATENT TITLE |
Reduced byproduct polyamine-epihalohydrin resins |
| PATENT ABSTRACT |
Processes for rendering a polyamine-epihalohydrin resin storage stable, including processes that prepare a storage stable resin and/or processes that treat resins. A composition containing a polyamine-epihalohydrin resin which includes CPD-forming species can be treated with at least one agent under conditions to at least one of inhibit, reduce and remove the CPD-forming species to obtain a reduced CPD-forming resin so that a composition containing the reduced CPD-forming polyamine-epihalohydrin resin when stored for 2 weeks at 50.degree. C., and a pH of about 2.5 to 3.5 contains less than about 250 ppm dry basis of CPD. The invention is also directed to a gelation storage stable reduced CPD-forming resin so that a composition containing the reduced CPD-forming polyamine-epihalohydrin resin, when stored at pH 1 for 24 hours at 50.degree. C. and measured at 24 hours, produces less than about 1000 ppm dry basis of CPD. A paper product containing the storage stable polyaminopolyamide-epihalohydrin resin, when corrected for adding at about a 1 wt % addition level of the polyaminopolyamide-epihalohydrin resin, contains less than about 250 ppb of CPD. Moreover, a resin can be prepared starting from a prepolymer having a low acid number or low concentration of acid end groups. The invention is also directed to papers containing the resins. |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | June 12, 2000 |
| PATENT PARENT CASE TEXT | This data is not available for free |
| PATENT CLAIMS |
What is claimed is: 1. A process for rendering a polyamine-epihalohydrin resin storage stable, comprising: treating a composition containing a polyamine-epihalohydrin resin which includes CPD forming species with at least one acidic agent, wherein the pH during treatment is about 1.1 or less; the time is for at least about 2 hours to at least about 24 hours, and the temperature is at least about 30.degree. C. to at least about 90.degree. C., wherein the temperature range is combined with the time period range in an inverse relationship, to at least one of inhibit, reduce and remove the CPD-forming species to obtain a gelation storage stable reduced CPD-forming resin so that the composition containing the reduced CPD-forming polyamine-epihalohydrin resin, when stored at pH 1 for 24 hours at 50.degree. C. and measured at 24 hours, produces less than about 500 ppm dry basis of CPD. 2. The process according to claim 1, wherein the polyamine-epihalohydrin resin comprises polyaminopolyamide-epihalohydrin resin. 3. The process according to claim 1, wherein the at least one acidic agent comprises a non-halogen inorganic acid. 4. The process according to claim 3, wherein the non-halogen acid comprises sulfuric acid. 5. The process according to claim 1, wherein following the treating with the at least one acidic agent, at least one basic agent is added to raise the pH of the resin composition to at least about 7. 6. The process according to claim 5, wherein following the treating with the at least one acidic agent, at least one basic agent is added to raise the pH of the resin composition to a range of about 8 to 12. 7. The process according to claim 6, wherein, prior to the treating a polyamine-epihalohydrin resin to obtain a reduced CPD-forming resin, the resin is contacted with at least one microorganism, or at least one enzyme isolated from the at least one microorganism, in an amount, and at a pH and temperature effective to dehalogenate residual quantities of organically bound halogen. 8. The process according to claim 7, wherein the at least one microorganism comprises at least one of Arthrobacter histidinolovorans (HK1), Agrobacterium radiobacter (HK7) and Burkholderia cepacia. 9. The process according to claim 6, wherein, subsequent to the subjecting a polyamine-epihalohydrin resin to obtain a reduced CPD-forming resin, the reduced CPD-forming resin is contacted with at least one microoganism, or at least one enzyme isolated from the at least one microorganism, in an amount, and at a pH and temperature effective to dehalogenate residual quantities of organically bound halogen. 10. The process according to claim 9, wherein the at least one microorganism comprises at least one of Arthrobacter histidinolovorans (HK1), Agrobacterium radiobacter (HK7) and Burkholderia cepacia. 11. The process according to claim 6, wherein, subsequent to the subjecting a polyamine-epihalohydrin resin to obtain a reduced CPD-forming resin and prior to basic agent addition, the reduced CPD-forming resin is contacted with at least one microoganism, or at least one enzyme isolated from the at least one microorganism, in an amount, and at a pH and temperature effective to dehalogenate residual quantities of organically bound halogen. 12. The process according to claim 8, wherein the at least one microorganism comprises a mixture comprising at least one of Arthrobacter histidinolovorans (HK1), Agrobacterium radiobacter (HK7) and Burkholderia cepacia. 13. The process according to claim 10, wherein the at least one microorganism comprises a mixture comprising at least one of Arthrobacter histidinolovorans (HK1), Agrobacterium radiobacter (HK7), and Burkholderia cepacia. 14. The process according to claim 6, wherein, subsequent to the treating a polyamine-epihalohydrin resin to obtain a reduced CPD-forming resin and prior to basic agent addition, the resin is treated to reduce at least one of epihalohydrins, epihalohydrin hydrolysis by-products and organic halogen bound to the polymer backbone. 15. The process according to claim 7, wherein the at least one microorganism comprises at least one of NCIMB deposit number 40274, NCIMB deposit number 40272 and NCIMB deposit number 40273. 16. The process according to claim 9, wherein the at least one microorganism comprises at least one of NCIMB deposit number 40274, NCIMB deposit number 40272 and NCIMB deposit number 40273. 17. The process according to claim 8, wherein the at least one microorganism comprises a mixture comprising at least one of NCIMB deposit number 40274, NCIMB deposit number 40272 and NCIMB deposit number 40273. 18. The process according to claim 10, wherein the at least one microorganism comprises a mixture comprising at least one NCIMB deposit number 40274, NCIMB deposit number 40272 and NCIMB deposit number 40273. 19. The process according to claim 1, wherein, prior to the treating a polyamine-epihalohydrin resin to obtain a reduced CPD-forming resin, the resin is contacted with at least one microorganism, or at least one enzyme isolated from the at least one microorganism, in an amount, and at a pH and temperature effective to dehalogenate residual quantities of organically bound halogen. 20. The process according to claim 1, wherein, subsequent to the subjecting a polyamine-epihalohydrin resin to obtain a reduced CPD-forming resin, the reduced CPD-forming resin is contacted with at least one microorganism, or at least one enzyme isolated from the at least one microorganism, in an amount, and at a pH and temperature effective to dehalogenate residual quantities of organically bound halogen. 21. The process according to claim 1, wherein the temperature is about 40.degree. C. to 90.degree. C. 22. The process according to claim 1, wherein, prior to the treating a polyamine-epihalohydrin resin to obtain a reduced CPD-forming resin, the resin is treated to reduce at least one of epihalohydrins, epihalohydrin hydrolysis by-products and organic halogen bound to the polymer backbone. 23. The process according to claim 1, wherein, subsequent to the treating a polyamine-epihalohydrin resin to obtain a reduced CPD-forming resin, the resin is treated to reduce at least one of epihalohydrins, epihalohydrin hydrolysis by-products and organic halogen bound to the polymer backbone. 24. The process according to claim 1, wherein the composition containing the reduced CPD-forming polyamine-epihalohydrin resin, when stored at pH 1 for 24 hours at 50.degree. C. and measured at 24 hours, produces less than about 50 ppm dry basis of CPD. 25. The process according to claim 1 wherein the reduced CPD-forming polyamine-epihalohydrin resin, when stored at pH 1 for 24 hours at 50.degree. C. and measured at 24 hours, produces less than about 250 ppm dry basis of CPD. 26. The process according to claim 25, wherein following the treating with the at least one acidic agent, at least one basic agent is added to raise the pH of the resin composition to a range of about 8 to 12. 27. The process according to claim 25 wherein the reduced CPD-forming polyamine-epihalohydrin resin, when stored at pH 1 for 24 hours at 50.degree. C. and measured at 24 hours, produces less than about 75 ppm dry basis of CPD. 28. The process according to claim 27, wherein following the treating with the at least one acidic agent, at least one basic agent is added to raise the pH of the resin composition to a range of about 8 to 12. 29. A process for preparing a paper product, comprising: treating a composition containing a polyamine-epihalohydrin resin which includes CPD-forming species with at least one acidic agent, wherein the pH during treatment is about 1.1 or less, the time is for at least about 2 hours to at least about 24 hours, and the temperature is at least about 30.degree. C. to at least about 90.degree. C., wherein the temperature range is combined with the time period range in an inverse relationship, to at least one of inhibit, reduce and remove the CPD-forming species to obtain a gelation storage stable reduced CPD-forming resin, and forming a paper product with the reduced CPD-forming polyamine-epihalohydrin resin, so that the paper product, when corrected for adding at about a 1 wt % addition level of the reduced CPD-forming resin, contains less than about 250 ppb of CPD. 30. The process according to claim 19, wherein the paper product contains less than about 50 ppb of CPD. 31. The process according to claim 19, wherein the polyamine-epihalohydrin resin comprises polyaminopolyamide-epichlorohydrin resin. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
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.sub.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 reacting wet strength compositions with an organic or inorganic base. These patents are incorporated by reference in their entireties. Moreover, U.S. application Ser. No. 09/001,787, filed Dec. 31, 1997, and Ser. No. 09/224,107, filed Dec. 22, 1998 to Riehle, and WO 99/33901, and which are incorporated by reference in their entireties, disclose amongst other features, a process for reducing the AOX content of a starting water-soluble wet-strength resin comprising azetidinium ions and tertiary aminohalohydrin, which includes treating the resin in aqueous solution with base to form treated resin, wherein at least about 20% of the tertiary aminohalohydrin present in the starting resin is converted into epoxide and the level of azetidinium ion is substantially unchanged, and the effectiveness of the treated resin in imparting wet strength is at least about as great as that of the starting wet-strength resin. The use of endcapping agents to prepare polyaminoamide prepolymers of controlled molecular weight is described in U.S. Pat. Nos. 5,786,429 and 5,902,862, which are incorporated by reference in their entireties. The endcapping agents described were either monofunctional carboxylic acids, monofunctional carboxylic esters or monofunctional amines. These polyaminoamides were subsequently reacted with a minimal amount of an intralinker to give highly branched polyamidoamines having either no or very low levels of reactive functionality. WO 99/09252 describes thermosetting wet strength resins prepared from end-capped polyaminoamide polymers. The endcappers used are monocarboxylic acids or monofunctional carboxylic esters, and are used to control the molecular weight of the polyaminamide in order to obtain wet strength resins with a high solids content. Each of the foregoing approaches has provided various results, and there has been a continuing need for improvement. SUMMARY OF THE INVENTION The present invention is directed 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). The present invention is also directed to various uses of polyamine-epihalohydrin resins having at least reduced formation of halogen containing residuals, such as wet strength agents. The present invention is also directed to polyamine-epihalohydrin resin products which have reduced levels of formation of CPD upon storage, particularly paper products. The present invention is also directed to the preparation of polyamine-epihalohydrin resins, especially polyaminopolyamide-epihalohydrin resins and/or the treatment of polyamine-epihalohydrin resins, especially polyaminopolyamide-epihalohydrin resins. The present invention is also directed to the preparation of storage stable polyamine-epihalohydrin resins, especially polyaminopolyamide-epihalohydrin resins and/or the treatment of polyamine-epihalohydrin resins, especially polyaminopolyamide-epihalohydrin resins to render such resins storage stable. In one aspect of the present invention wherein the polyamine-epihalohydrin resin is treated to obtain a storage stable product, the present invention is directed to a process for rendering a polyamine-epihalohydrin resin storage stable, comprising treating a composition containing polyamine-epihalohydrin resin which includes CPD-forming species with at least one agent under conditions to at least one of inhibit, reduce and remove the CPD-forming species to obtain a gelation storage stable reduced CPD-forming resin so that composition containing the reduced CPD-forming polyamine-epihalohydrin resin when stored for 2 weeks at 50.degree. C., and a pH of about 2.5 to 3.5 contains less than about 250 ppm dry basis of CPD, preferably less than about 150 ppm dry basis of CPD after two weeks, more preferably less than about 75 ppm dry basis of CPD after two weeks, even more preferably less than about 40 ppm dry basis of CPD after two weeks, and even more preferably less than about 10 ppm dry basis of CPD after two weeks. Moreover, the present invention is also directed to a process for rendering a polyamine-epihalohydrin resin storage stable, comprising treating a composition containing a polyamine-epihalohydrin resin which includes CPD-forming species with at least one agent under conditions to at least one of inhibit, reduce and remove the CPD-forming species to obtain a gelation storage stable reduced CPD-forming resin so that a composition containing the reduced CPD-forming polyamine-epihalohydrin resin, when stored at pH 1 for 24 hours at 50.degree. C. and measured at 24 hours, produces less than about 1000 ppm dry basis of CPD, more preferably produces less than about 750 ppm dry basis of CPD, even more preferably produces less than about 500 ppm dry basis of CPD, even more preferably produces less than about 250 ppm dry basis of CPD, even more preferably produces less than about 150 ppm dry basis of CPD, even more preferably produces less than about 100 ppm dry basis of CPD, even more preferably produces less than about 75 ppm dry basis of CPD, even more preferably produces less than about 50 ppm dry basis of CPD, even more preferably-produces less than about 25 ppm dry basis of CPD, even more preferably produces less than about 15 ppm dry basis of CPD, even more preferably produces less than about 5 ppm dry basis of CPD, and even more preferably produces less than about 3 ppm dry basis of CPD, and even more preferably produces less than about 1 ppm dry basis of CPD. The present invention is also directed to a storage stable polyaminopolyamide-epihalohydrin resin, the polyaminopolyamide-epihalohydrin resin when stored as an aqueous composition containing the resin, when stored at pH 1 for 24 hours at 50.degree. C. and measured at 24 hours, produces less than about 1000 ppm dry basis of CPD, more preferably produces less than about 750 ppm dry basis of CPD, even more preferably produces less than about 500 ppm dry basis of CPD, even more preferably produces less than about 250 ppm dry basis of CPD, even more preferably produces less than about 150 ppm dry basis of CPD, even more preferably produces less than about 100 ppm dry basis of CPD, even more preferably produces less than about 75 ppm dry basis of CPD, even more preferably produces less than about 50 ppm dry basis of CPD, even more preferably produces less than about 25 ppm dry basis of CPD, even more preferably produces less than about 15 ppm dry basis of CPD, even more preferably produces less than about 5 ppm dry basis of CPD, and even more preferably produces less than about 3 ppm dry basis of CPD, and even more preferably produces less than about 1 ppm dry basis of CPD. In another aspect, the present invention is also directed to a storage stable polyaminopolyamide-epihalohydrin resin, the polyaminopolyamide-epihalohydrin resin being capable of forming a paper product, so that a paper product containing said polyaminopolyamide-epihalohydrin resin, when corrected for adding at about a 1 wt % addition level of the polyaminopolyamide-epihalohydrin resin, contains less than about 250 ppb of CPD, more preferably less than about 100 ppb of CPD, more preferably less than about 50 ppb of CPD, more preferably less than about 10 ppb of CPD and even more preferably less than about 1 ppb of CPD. A paper product containing the reduced CPD-forming resin, when corrected for adding at about a 1 wt % addition level of the reduced CPD-forming resin, preferably contains less than about 250 ppb of CPD, more preferably less than about 100 ppb of CPD, more preferably less than about 50 ppb of CPD, more preferably less than about 10 ppb of CPD and even more preferably less than about 1 ppb of CPD. In another aspect of the present invention involving preparation of the polyamine-epihalohydrin so as to have a reduced acid number, the present invention is directed to the production of polyaminopolyamide-epihalohydrin resins having reduced acid number, compositions and solutions containing such resins, as well as products, such as paper products, containing such resins. In another aspect of the present invention, a storage stable polyaminopolyamide-epihalohydrin resin is provided, wherein the polyaminopolyamide-epihalohydrin resin when stored as an aqueous composition containing the resin for 2 weeks at 50.degree. C., and a pH of about 2.5 to 3.5 contains less than about 250 ppm dry basis of CPD, preferably less than about 150 ppm dry basis of CPD after two weeks, more preferably less than about 75 ppm dry basis of CPD after two weeks, even more preferably less than about 40 ppm dry basis of CPD after two weeks, and even more preferably less than about 10 ppm dry basis of CPD after two weeks. In still another aspect, the present invention is directed to a polyaminopolyamide-epihalohydrin resin formed by reacting polyaminoamide prepolymer with epihalohydrin, the polyaminoamide prepolymer having an acid functionality less than about 0.5 milliequivalents/dry gram of prepolymer, and said polyaminopolyamide-epihalohydrin resin being subjected to a treatment to reduce at least one of epihalohydrins, epihalohydrin hydrolysis by-products and CPD forming species. Still further, the polyaminopolyamide-epihalohydrin resin can be a polyaminopolyamide-epihalohydrin resin produced from polyaminoamide prepolymer having an acid functionality less than about 0.5 milliequivalents/dry gram of prepolymer, more preferably less than about 0.25 milliequivalents/dry gram of prepolymer, more preferably less than about 0.1 milliequivalents/dry gram of prepolymer, more preferably less than about 0.075 milliequivalents/dry gram of prepolymer, even more preferably less than about 0.05 milliequivalents/dry gram of prepolymer. Still further, the polyaminopolyamide-epihalohydrin resin can be a polyaminopolyamide-epihalohydrin resin produced from polyaminoamide prepolymer having an acid end group concentration of less than about 5%, as measured by .sup.13 C NMR analysis, more preferably, an acid end group concentration of less than about 2.5%, as measured by .sup.13 C NMR analysis, more preferably an acid end group concentration of less than about 1%, as measured by .sup.13 C NMR analysis, more preferably an acid end group concentration less than about 0.7%, as measured by .sup.13 C NMR analysis, and even more preferably an acid end group concentration of less than about 0.5%, as measured by .sup.13 C NMR analysis. In another aspect of the present invention, the prepolymer can have a RSV of about 0.075 to 0.2 dL/g, more preferably about 0.1 to 0.15 dL/g, and is preferably at least about 0.05 dL/g, more preferably at least about 0.075 dL/g, and even more preferably at least about 0.1 dL/g. As noted above, the composition preferably contains less than about 150 ppm dry basis, more preferably less than about 75 ppm dry basis, more preferably less than about 40 ppm dry basis, more preferably less than about 10 ppm dry basis of CPD after two weeks. Moreover, the present invention is also directed to a process for preparing a paper product, comprising treating a compositon containing polyamine-epihalohydrin resin which includes CPD-forming species with at least one agent under conditions to at least one of inhibit, reduce and remove the CPD-forming species to obtain a gelation storage stable reduced CPD-forming resin, and forming a paper product with the reduced CPD-forming polyamine-epihalohydrin resin, so that a paper product, when corrected for adding at about a 1 wt % addition level of the reduced CPD-forming resin, contains less than about 250 ppb of CPD, preferably less than about 100 ppb of CPD, even more preferably less than about 50 ppb of CPD, even more preferably less than about 10 ppb of CPD, and even more preferably less than about 1 ppb of CPD. In still another aspect, the present invention is directed to a process of producing a polyaminoamide prepolymer by reacting polyalkyleneamine with dicarboxylic acid and/or dibasic ester in a prepolymer forming reaction, and post-adding at least one amine at a later stage of the prepolymer forming reaction. The amine can be added in an amount so that a total molar quantity of polyalkylenepolyamine plus post-added amine is greater than a total molar amount of dicarboxylic acid. Preferably, the prepolymer forming reaction is at least about 70% complete at time of addition of the post-added amine, more preferably at least about 80% complete, and even more preferably at least about 90% complete. The post-added amine can be a monofunctional amine and/or a polyamine, such as a polyalkyleneamine. In the various reactions, the dicarboxylic acid can comprise at least one of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid and azelaic acid; the dibasic ester can comprise at least one of dimethyl adipate, diethyl adipate, dimethyl glutarate, diethyl glutarate, dimethyl succinate and diethyl succinate, and the polyalkyleneamine can comprise at least one of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dipropylenetriamine, methylbisaminopropylamine, bis-hexamethylenetriamine and methylbisaminopropylamine. The polyamine-epihalohydrin resin can comprise polyaminopolyamide-epihalohydrin resin, preferably polyaminopolyamide-epichlorohydrin resin, and polyaminoureylene-epihalohydrin resin, preferably polyaminoureylene-epichlorohydrin resin. The prepolymer can comprise endcapped prepolymer, amine excess prepolymer and post-added amine prepolymer. The at least one agent can comprise at least one acidic agent. The at least one acidic agent is preferably added to provide an initial pH of less than about 2, preferably less than about 1, or about 1, the temperature is at least about 30.degree. C., preferably about 30.degree. C. to 140.degree. C., more preferably about 40.degree. C. to 90.degree. C., with preferred temperatures being at least about 50.degree. C., and the time is at least about 2 hours. The at least one acidic agent can be added to provide an initial pH of about 1, the temperature can be about 50.degree. C., and the time can be about 24 hours. The at least one acidic agent can added to provide an initial pH of about 1, the temperature can be about 60.degree. C., and the time can be about 12 hours. The at least one acidic agent can be added to provide an initial pH of about 1, the temperature can be about 70.degree. C., and the time can be about 6 hours. The at least one acidic agent can be added to provide an initial pH of about 1, the temperature can be about 80.degree. C., and the time can be about 3 hours. The at least one acidic agent can comprise a non-halogen inorganic acid, preferably sulfuric acid. Following the treating with the at least one acidic agent, at least one basic agent can be added to raise the pH of the resin solution to at least about 7, preferably to at least about 8, with a preferred range of about 8 to 12. The resin solution during base treatment preferably has a temperature of about 40.degree. C. to 70.degree. C. Following the addition of the at least one basic agent, an acidic agent can be added in an amount effective to gel stabilize the resin solution. The at least one agent can comprise at least one basic agent. The resin can comprise a resin formed in a polyamide-epihalohydrin reaction having a molar ratio of epihalohydrin to secondary amine group of less than 1, more preferably the molar ratio of epihalohydrin to secondary amine group is less than about 0.975, with a preferred range of the molar ratio of epihalohydrin to secondary amine group being about 0.5 to 0.975, more preferably the molar ratio of epihalohydrin to secondary amine group being about 0.8 to 0.975. The at least one basic agent can raise the pH of the composition containing the polyamine-epihalohydrin resin to a pH of at least about 8, more preferably at least about 9, more preferably a pH of at least about 10, and the pH is preferably less than about 12.5, with a preferred pH range pH about 10 to 12. The composition preferably has a temperature of at least about 20.degree. C., more preferably a temperature of at least about 40.degree. C., with one temperature range being about 20.degree. C. to 80.degree. C. The composition can have a temperature of about 50.degree. C., a pH of about 11.5, and a treatment time is about 5 minutes. The composition can have a temperature of about 55.degree. C., a pH of about 10.5 to 11.5, and a treatment time is about 5 minutes. The reduced CPD-forming resin can be acid stabilized, such as to a pH from about 2.5 to 4. The at least one agent can comprise at least one enzymatic agent, such as at least one of esterases, lipases and proteases, preferably ALCALASE. The at least one agent can comprise at least one pH modifying agent to obtain a pH of about 5.5 to 7. The composition can have a temperature of about 30.degree. C., a pH of about 6 and a treatment time of about 6 days. The composition can have a temperature of about 50.degree. C., a pH of about 6 and a treatment time of about 6 hours. Prior and/or subsequent to treating a polyamine-epihalohydrin resin to obtain a reduced CPD-forming resin and/or after production of a low acid number resin, the resin can be contacted with at least one microorganism, or at least one enzyme isolated from the at least one microorganism, in an amount, and at a pH and temperature effective to dehalogenate residual quantities of organically bound halogen. The at least one microorganism can comprise at least one of Arthrobacter histidinolovorans HK1, Burkholderia cepacia and Aerobacterium radiocacter HK7. The at least one microorganism can comprise a mixture comprising at least one of Agrobacterium radiobacter HK7 and Burkholderia cepacia, and Arthrobacter histidinolovorans HK1. Moreover, prior and/or subsequent to the treating a polyamine-epihalohydrin resin to obtain a reduced CPD-forming resin and/or after production of a low acid number resin, the resin can be treated to reduce at least one of epihalohydrins, epihalohydrin hydrolysis by-products and organic halogen bound to the polymer backbone. The present invention is also directed to paper products treated with resins produced according to the present invention, to reduced CPD-forming resin produced according to the present invention, and aqueous compositions comprising the reduced CPD-forming resin according to the present invention, and such aqueous compositions including at least one polyalkylene polyamine-epihalohydrin resin. The paper product can comprise a paper product which comes into contact with food products, such as a tea bag or coffee filter, or packaging board, or tissue and towel. |
| PATENT EXAMPLES | available on request |
| PATENT PHOTOCOPY | available on request |
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