Office Action 2: Final Rejection (2025-04-17)
Rejection types: 103 - Obviousness, 112 - Written Description/Enablement

CLAIMS:
Amendments to the Claims

This listing of claims will replace all prior versions, and listings, of claims in the application:

Listing of Claims:

Attorney Docket: 1128OUS

1\. (Currently amended) A method of processing a solution of vinylamine-containing polymers comprising;SVG {EMBED HERE} 0.1470.793SVG {EMBED HERE} 0.156.373SVG {EMBED HERE} 0.154.443SVG {EMBED HERE} 0.153.867SVG {EMBED HERE} 0.1431.033SVG {EMBED HERE} 0.156.357SVG {EMBED HERE} 0.154.863SVG {EMBED HERE} 0.1330.423SVG {EMBED HERE} 0.0970.683- providing the solution of vinylamine-containing polymer,\_wherei - circulating the solution through a nanofiltration membrane and/or an ultrafiltration membrane a...()- collecting the vinylamine-containing polymer retentate -aire-
2\. (Cancelled)SVG {EMBED HERE} 0.156.36
3\. (Cancelled)SVG {EMBED HERE} 0.1174.02
4\. (Currently amended) The method according to The method according to SVG {EMBED HERE} 0.1130.053j, wherein the salts and/or by- products are permeable molecules, unwanted reaction salts, small proteins, organic and/or inorganic solvents, residual monomers, monomeric impurities, monomer decomposition byproducts, monomer stabilizers, and byproducts from initiator decomposition, and/or

impurities coming from cationizing and/or alkylating agent containing amine or amide functionality.

5\. (Original) The method according to claim 4, wherein the salts and/or by-products are monomeric impurities.
6\. (Currently amended) The method according to claim H, wherein the salts and by- products are impurities from reactions involving N-vinylformamide polymerization and copolymerization with other functional monomers, hydrolysis of polyvinylformamide by acid or caustic treatment, and post polymerization modification of vinylamine-containing polymers with functional monomers.SVG {EMBED HERE} 0.080.04
7\. (Currently amended) The method of claim 1, wherein collecting the vinylamine- containing polymer retentate comprises thevinylamine-containing polymer retentate having a higher concentration of vinylamine-containing polymer than the solution prior to circulating through the nanofiltration membrane and/or an ultrafiltration membrane.SVG {EMBED HERE} 0.151.277
8\. (Currently amended) The method according to claim 1, wherein the nanofiltration membrane and/or an ultrafiltration membrane has a molecular weight cut-off of i:=wf-SVG {EMBED HERE} 0.1276.374-999-SVG {EMBED HERE} 0.1170.97 800 Da.SVG {EMBED HERE} 0.1130.64

9\. (Original) A method of improving drainage in a papermaking process comprising adding the retentate according to claim 1, to a papermaking furnish.
10\. (Currently amended) A method of preparing a solution of high molecular weight vinylamine-containing polymers comprising,- providing a solution of vinylamine-containing polymer SVG {EMBED HERE} 0.1131.143
SVG {EMBED HERE} 0.154.357 comprising a low molecular weight vinylamine polymer component and a high molecular weight vinylamine polymer component;- circulating the solution through a nanofiltration and/or ultrafiltration membrane havingamolecularweightcut-offofSVG {EMBED HERE} 0.1170.30about\_\_\_99SVG {EMBED HERE} 0.1372.027thereby separating a fraction of low molecular weight vinylamine-containing polymer from a SVG {EMBED HERE} 0.1130.503SVG {EMBED HERE} 0.0870.557 of high molecular weight vinylamine-containing polymer; andcollecting the ofthe higher molecular vinylamine-containing
11\. (Cancelled)SVG {EMBED HERE} 0.156.347
12\. (Original) The method according to claim 11, wherein the weight average molecular weight of the collected fraction of vinylamine-containing polymer retentate is from about 20,000 to about 750,000 Da.SVG {EMBED HERE} 0.155.633

13\. (Original) The method according to claim 12, wherein the weight average molecular weight of the collected fraction of vinylamine-containing polymer retentate is from about 50,000 to about 400,000 Da.

14\. (Original) The method according to claim 13, wherein the weight average molecular weight of the collected fraction of vinylamine-containing polymer retentate is from about 100,000 to about 250,000 Da.

OFFICE ACTION:
DETAILED ACTION
Notice of Pre-AIA  or AIA  Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Response to Arguments
Applicant’s amendments and arguments, filed 3/28/2025, have overcome the rejections based on 35 U.S.C. 102.  Said rejections have been withdrawn.  All rejections of Claims 2-3 and 11 have also been withdrawn due to cancellation of the claims.  The remaining rejections over the prior art have been modified to address the amendments to the claims and in view of newly cited prior art.
Applicant’s arguments have been carefully considered, but they are not convincing.
Regarding the argument that the prior art uses the filtered polymers for a different purpose, Applicant recognizes that Decker et al discloses using ultrafiltration with a membrane having a cut-off value as low as 1,000 Daltons, and that the instant claims recite a cut-off value of about 500 Daltons to 1,000 Daltons. One of ordinary skill in the art would have found no significant difference in the process between using a cut-off of 1,000 Daltons or slightly above 1,000 Daltons and a cut off of slightly lower than 1,000 Daltons.  Applicants have not provided convincing evidence of the criticality of the claimed range of about 500 daltons to 1000 Daltons.  Absent convincing evidence of such criticality and/or unexpected results commensurate in scope with the claims, it would have been obvious to one of ordinary skill in the art to select an ultrafiltration membrane having a cut-off of 1,000 Daltons or slightly above 1,000 Daltons for the ultrafiltration with a reasonable expectation of obtaining a retentate comprising a suitable polymer solution that has a reduced amount of salts compared to the solution prior to circulating through the ultrafiltration membrane.
Regarding the argument that Decker et al does not disclose circulating the polymer through membranes having the claimed cut-off values, the issue is addressed in the modified rejections detailed herein.
Regarding the assertion that It was only found through the careful selection of the membrane that removal of impurities could be accomplished with no loss of functional polymer or degradation of the polymer, Applicants have not provided convincing evidence commensurate in scope with the claims of the criticality of the claimed range of about 500 daltons to 1000 Daltons.
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(d):
(d) REFERENCE IN DEPENDENT FORMS.—Subject to subsection (e), a claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed. A claim in dependent form shall be construed to incorporate by reference all the limitations of the claim to which it refers.
The following is a quotation of pre-AIA  35 U.S.C. 112, fourth paragraph:
Subject to the following paragraph [i.e., the fifth paragraph of pre-AIA  35 U.S.C. 112], a claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed. A claim in dependent form shall be construed to incorporate by reference all the limitations of the claim to which it refers.
Claims 12-14 are rejected under 35 U.S.C. 112(d) or pre-AIA  35 U.S.C. 112, 4th paragraph, as being of improper dependent form for failing to further limit the subject matter of the claim upon which it depends, or for failing to include all the limitations of the claim upon which it depends.  Claims 12-14 depend from a cancelled claim, and therefore, fail to reference a claim previously set forth and then specify a further limitation of the subject matter claimed.  Applicant may cancel the claim(s), amend the claim(s) to place the claim(s) in proper dependent form, rewrite the claim(s) in independent form, or present a sufficient showing that the dependent claim(s) complies with the statutory requirements.
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA  35 U.S.C. 102 and 103 (or as subject to pre-AIA  35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA  to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
. Claims 1, 4-10 and 12-14 are rejected under 35 U.S.C. 103 as being anticipated by Decker et al US 6,716,311 in view of Bennett et al (US 2006/0065599).
Bridging paragraph of col. 5-6 of the US 311 teaches that polymers containing vinylamine units are preferably used in salt-free form. Salt-free aqueous solutions of polymer containing vinylamine units can be prepared, for example, from the salt- containing polymer solutions with the aid of dialysis or ultrafiltration through suitable membranes with cut-offs of, for example, from 1,000 to 500,000 Daltons, which overlays or touches the upper end of the claimed range.  One of ordinary skill in the art would have found no significant difference in the ultrafiltration between using a cut-off of 1000 Daltons or slightly above 1000 Daltons and a cut off of slightly lower than 1000 Daltons.
Applicants have not provided convincing evidence of the criticality of the claimed range of about 500 daltons to 1000 Daltons.  Absent convincing evidence of such criticality and/or unexpected results commensurate in scope with the claims, it would have been obvious to one of ordinary skill in the art to select an ultrafiltration membrane having a cut-off of 1,000 Daltons for the ultrafiltration with a reasonable expectation of obtaining a retentate comprising a suitable polymer solution that is salt-free or, at least, has a reduced amount of salts compared to the solution prior to circulating through the ultrafiltration membrane.
Other polymers containing amino and/or ammonium groups can also be obtained in salt-free form with the aid of dialysis or ultrafiltration. In the ultrafiltration through a membrane having the abovementioned cut-off, fractionation of the polymer resulting in polymer having a relatively narrow molar mass distribution Mw /Mn is achieved in addition to removal of salts which are formed. The fractions of polymers having a narrow distribution are obtained as retentate in the ultrafiltration.
Decker et al discloses molar masses of polymers containing vinylamine units from 1,000 to 10 million Daltons (col 5, lines 55-57), which significantly overlays the claimed ranges or, at least, obtaining vinylamine-containing polymers having a claimed molecular weight would have been obvious absent convincing evidence of unexpected results commensurate in scope with the claims.
Decker et al does not disclose circulating the through circulating the solution through a nanofiltration membrane and/or an ultrafiltration membrane having a molecular cut-off from about 500 Dalton to 1,000 Dalton.
In the same field of endeavor, Bennett et al discloses a process for reducing the content of water-soluble salts of aqueous solutions of polymers containing vinylamine groups by ultrafiltration to achieve a desired reduced salt content.  Bennett et al discloses the theory of ultrafiltration, which is generally known to those of ordinary skill in the art, as follows ([0015]-[0019]);
“The theory of ultrafiltration states that during diafiltration, micro solutes (ions and low molecular weight polymers) freely permeate through the membranes and maintain the same concentration on both sides of the membrane. The concentration of membrane permeable species (sodium formate) remaining in the feed solution can be calculated by the following:
PNG
media_image1.png
35
148
media_image1.png
Greyscale
where:
PNG
media_image2.png
136
393
media_image2.png
Greyscale
Vd/Vo is the number of wash volumes (cycles or recirculation  that have been completed. One wash cycle (or wash volume) means the addition of an equivalent amount of fresh water to the starting solution volume and removal of the same amount of permeate solution. According to the equation, 95% of the initial sodium formate is removed after 3 wash volumes and 98% of the initial formate is removed after 4 wash volumes have been completed.”
Bennett et al shows that circulating the solution through the ultrafiltration membrane more than once may be necessary to achieve the desired reduction in salts and by-products.  To achieve the desired degree of purity for this process 4-5 wash cycles are normally required.  Therefore, the number of cycles, or the number of times the solution is circulated through the ultrafiltration membrane, is a result effective variable.
It would have been obvious to one of ordinary skill in the art to circulate the solution through the ultrafiltration membrane multiple times to obtain a desired reduction in salts and by-products.  Collecting the obtained vinylamine-containing polymer retentate would have been obvious as a purpose for performing the ultrafiltration.
Regarding claim 4, as noted above the salts are removed through filtration.
Regarding claim 5, the impurities include monomeric salts from which the polymers are made (col. 5, lines 5-61).
Regarding claim 6, the polymers are made from hydrolysis from polyvinyl formamide (col. 5, lines 5-61).
Regarding claim 7, it would be inherent that the retentate would have a high concentration of polymers once it is screened through the membrane that filters out such polymer.
Regarding claim 8, Bennett et al discloses that the cut-off value of the ultrafiltration or nanofiltration membrane can be as low as 400 Daltons and up to 10,000 Daltons, depending on the k-value (which is related to the molecular weight) of the polymer being filtered to achieve the [0039].  Therefore, the cut-off value for the membrane is also a result effective variable and it would have been obvious to one of ordinary skill in the art to determine the claimed cut-off value depending on the molecular weight of the polymer being filtered and the desired molecular weight to be obtained.
Regarding claim 9, the abstract of Decker et al teaches that the polymers can be used as fixing agents in papermaking stock, therefore adding the retentate to a papermaking furnish would have been obvious.
Regarding claim 10, as noted previously in Decker et al, the membrane collects the higher molecular weight polymer fraction in the retentate from the ultrafiltration, while polymers of low molecular weights are separated in the permeate from the ultrafiltration.
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.

APPLICANT REBUTTAL: REMARKS/ARGUMENTSClaims 1, 4-10, and 12-14, were pending in the application, claims 1, 4-10, and 12-14, have been rejected. Claims 1, 4, 5, 10, and 14, have been amended; and claims 12 and 13, cancelled.Therefore, claims 1, 4-10, and 14, are pending and under consideration. No new matter has been added.Amendments to the Claims Claim 1 has been amended to clarify that the present method relates to "removing salts, by-products, and low molecular weight polymers from a solution of vinylamine-containing polymer." The solution comprises salts and by-products, which in addition to removing at least a portion of the salts and by-products, separates a low molecular retentate from a high molecular weight retentate.Claims 4 and 5, have been amended so the wording coincides with the wording of amended claim 1, i.e., "wherein the salts and by-products..." (Abstract. Pg. 1, para. [0001]).Claim 10, has been amended to clarify that the retentate that is recovered has a weight average molecular weight of from about 10,000 to about 1,000,000. Applicant had inadvertently an unnecessarily limited the scope of the claim 10. Support can be found at page 6, para. [0030] and original claim 11.Claims 12 and 13 have been cancelled.CLAIM REJECTION UNDER 35 USC § 112 Claims 12-14, have been reject as being indefinite under 35 U.S.C. 112(d) or 35 U.S.C. 112 (pre-AIA), fourth paragraph. Specifically. claims 12-14 depend upon a cancelled claim.Applicants have cancelled claims 12 and 13; and have amended claim 14 to depend on claim 10.Therefore, this should now be considered moot.CLAIM REJECTION UNDER 35 USC § 103 Claims 1, 4-10, and 12-14, are rejected under 35 U.S.C. 103 as being unpatentable over US Patent 6,716,311 (hereinafter referred to as "Decker") in view of Bennett et al (US 2006/0065599). Applicants traverse this rejection.Applicants have been able to demonstrates improved drainage performance, indicating that the removal of low molecular weight polymer fractions, salts, and other impurities enhances product performance (see Table 3). Significantly, neither reference cited by the examiner discloses the performance benefits of being able to remove salts, by-products, and low molecular weight polymer species. The current studies and supporting data have shown significant performance improvements by not only removing salts and by-products but also provides a process for separating the higher molecular weight retentate from the lower molecular weight retentate.Decker relates to modified cationic polymers which are obtainable by reacting water- soluble polymeric compounds containing NH groups with crosslinking agents and processes for their preparation and their use in papermaking (col. 1, lines 5-9) . Although, Decker discloses passing a PVAM through a membrane filtration, the objective is to improve the reactivity between components a and b in the reaction.Applicants found using the current method, dry strength, wet strength, retention, and drainage in a papermaking process and product could be enhanced using the method as currently claimed. Based on the disclosure of Decker, there is no suggestion to include a circulation step in the process. Therefore, one of ordinary skill in the art would not be motivated to include the step with expectations of improved performance.As the Examiner submits, Decker fails to teach this certain critical aspects of the present technology, i.e., circulating the vinylamine-containing polymer through membranes having cut- offs below 1,000 Da. It is very relevant that Decker does not teach circulating the polymer through membranes having cut-offs offrom about 500 Da to 1,000 Da. In fact, Applicants teach in claim 8, that the cut-off is 800 Da.However, the Examiner alleges that Bennett, in the same field of endeavor, discloses a filtration process for reducing the content of water-soluble salts to achieve a reduced salt content.Applicants respectfully disagree that Decker and Bennett are in the same field of endeavor.Decker relates to modified cationic polymers which can be obtained by reacting (a) water- soluble, polymeric compounds containing NH groups with (b) compounds which are at least bifunctional with regard to NH groups and a method for producing the polymers by reacting the compounds of groups (a) and (b), and to the use of the modified cationic polymers during the production of paper as fixing agents for papermaking stock containing interfering substances (Abstract). Bennett relates to a process for reducing the content of water-soluble salts of aqueous solutions of polymers containing vinylamine groups by ultrafiltration and use of the polymers in the manufacture of multicomponent superabsorbent gels (pg. 1, para. [0001]). It is also the object of Bennett to "reducing the content of water soluble salts...with practically no loss of polyamine" (pg. 1, para. [0006], emphasis added).In addition, Bennett describes salt removal from a polymer solution with a polymer concentration of at least 7% by weight. This implies that the PVAm content in the diluted solution is at least 7%, excluding the salt. Paragraph [0046] further specifies that the results are based on a starting solution containing 13% sodium formate and 8% PVAm. However, the patent does not explicitly disclose a dilution factor.In contrast, Applicants clearly show (see Table 1) that the diluted polymer solution has a total solids content (polymer + salt) of 10.09%. The VSEP composite permeate collected has a solids content of 5.57%, indicating that the starting diluted polymer solution contains less than 7% polymer.Applicants have observed that the viscosity of the starting (diluted) polymer solution significantly affects membrane efficiency. This viscosity is influenced by polymer concentration, pH, salt content, and other factors.Looking at example 2 in Bennett (pg. 4, para. [0043]), it is taught that there is amine loss during ultrafiltration, indicating that there is polymer degradation during membrane processing.The results of the examples in the present application, i.e., the drainage performance data and comparison with the regular product (Table 3), provide indirect evidence that the polymer remains intact.It was only found through the careful selection of the membrane that removal of impurities could be accomplished with no loss of functional polymer or degradation of the polymer (pg. 5, para. [0021]).Finally, the current technology provides for a solution of vinylamine-containing polymer, wherein the polymer comprises salts and by-products formed during vinylamine-containing polymer synthesis and/or modification of a vinylamine-containing polymer solution. The objective of Decker is to provide novel polymers which are effective as fixing agents in papermaking (col. 1, lines 54-56). Different objectives are clearly met using different methods.To go even further, the Applicant herein cites the decision of the PTAB in Lenovo Holding Company, Inc., v. Photonic Imaging Solutions, Inc., (IPR2019-01075) for the Office's consideration. As the PTAB makes clear "[a] determination of obviousness cannot be reached where the record 'lacks explanation as to how or why the references would be combined to produce the claimed invention. The 'factual inquiry' into the reasons for 'combining references must be thorough and searching, and the need for specificity pervades.' Petitioner's statement that a POSITA could have...does not adequately explain how or why the referenced would have been combined to arrive at the claimed invention" (emphasis added). Moreover, the PTAB focuses on Belden Inc. v. Berk-Tek in citing that obviousness concerns whether a skilled artisan not only could have made but would have been motivated to make the combinations or modifications of prior art to arrive at the claimed invention.Decker relates to modified cationic polymers which are obtainable by reacting water- soluble polymeric compounds containing NH groups with crosslinking agents, processes for their preparation and their use in papermaking (Abstract, col. 1, lines 5-9). Bennett relates to a process for reducing the content of water-soluble salts of aqueous solutions of polymers containing vinylamine groups by ultrafiltration and use of the polymers in the manufacture of multicomponent superabsorbent gels (pg. 1, para. [0001]).CONCLUSIONIn view of Applicants' amendments and remarks, it is respectfully submitted that Examiner's rejections of claims 1-14, have been overcome. Accordingly, Applicants respectfully submit that the application, as amended, is now in condition for allowance, and such allowance is therefore earnestly requested. Should the Examiner have any questions or wish to further discuss this application and amended claims, Applicants request that the Examiner contact the Applicants' attorneys at 480-361-0466.No fees are believed to be due with this response. However, if there are any other fees required to have this amendment entered or to keep the application pending, the Commissioner is hereby authorized to charge Deposit Account No. 502091 for any fee which may be due.Respectfully submitted,

NEXT OFFICE ACTION: DETAILED ACTION
Notice of Pre-AIA  or AIA  Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection.  Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.  Applicant's submission filed on 7/17/2025 has been entered.
Response to Arguments
Applicant’s amendments and arguments, filed 7/17/2025, have been fully considered and are persuasive. All rejections have been withdrawn.
Examiner’s Amendment
An examiner’s amendment to the record appears below. Should the changes and/or additions be unacceptable to applicant, an amendment may be filed as provided by 37 CFR 1.312. To ensure consideration of such an amendment, it MUST be submitted no later than the payment of the issue fee.
Authorization for this examiner’s amendment was given in an interview with MICHAEL J. HERMAN on 7/22/2025.
The application has been amended as follows:
In Claim 1, 4th line from the end, the word “the” following the word “collecting” has been deleted and the word  --a--  inserted therefor.
Allowable Subject Matter
The following is an examiner’s statement of reasons for allowance: Decker et al and Bennett et al are the nearest prior art.  Decker et al discloses ultrafiltration of solutions of polymer containing vinylamine units through a membrane having a cut-off value from 1,000 to 500,000 Da, which touches the upper limit of the claimed range of about 500 Da to 1,000 Da. Decker et al prefers a cut-off from 10,000 to 300,000 Da.  Bennett et al discloses a cut-off preferably at least 2,000 or at least 4,000, such as from 9,000 to 100,000, with the cut-off dependent on the K value of the polymer. One of ordinary skill in the art would have been led to use a membrane cut-off significantly above the claimed range.
Any comments considered necessary by applicant must be submitted no later than the payment of the issue fee and, to avoid processing delays, should preferably accompany the issue fee.  Such submissions should be clearly labeled “Comments on Statement of Reasons for Allowance.”
Conclusion

CITED REFERENCE SUMMARIES: Ref US20060065599A1: [content unavailable]
Ref US20060065599: Claims:
1. A process for reducing a content of water-soluble salts of an aqueous solution of a polymer containing vinylamine groups by ultrafiltration to achieve a residual salt content of 1 to 10% by weight based on total solution solids in the polymer solution, which comprises a step of feeding an aqueous salt-containing solution of a vinylamine group containing polymer at a polymer concentration of at least 7% by weight to an ultrafiltration unit and removing the water-soluble salts with a permeate from the feed solution by adding thereto less than 4 parts by weight of water per one part by weight of the feed solution, wherein the efficiency of the ultrafiltration unit, which is defined as the passage of salt across the membrane, is greater than 100%.
2. A process for reducing a content of water-soluble salts of an aqueous solution of a polymer containing vinylamine groups by ultrafiltration to achieve a residual salt content of 1 to 10% by weight based on total solution solids in the polymer solution, which comprises feeding an aqueous salt-containing solution of a vinylamine group containing polymer at a polymer concentration of at least 7% by weight to an ultrafiltration unit and removing the water-soluble salts with a permeate from the feed solution by adding thereto less than 4 parts by weight of water per one part by weight of the feed solution, wherein the ultrafiltration unit comprises spiral wound polymer membranes or vibratory shear membranes.
3. The process of claim 1 wherein no more than three parts by weight of water are added to one part by weight of the feed.
4. The process of claim 1 wherein the ultrafiltration unit comprises vibratory shear membranes.
5. The process of claim 4 wherein the ultrafiltration unit comprises vibratory shear membranes having a molecular weight cut off of at least 300.
6. The process of claim 1 wherein the membranes of the ultrafiltration unit have a molecular weight cut off of at least 2,000.
7. The process of claim 1 wherein the membranes of the ultrafiltration unit have a molecular cut off of at least 4,000.
8. The process of claim 1 wherein the membranes of the ultrafiltration unit have a molecular weight cut off of from 9,000 to 100,000.
9. The process of claim 1 wherein the water-soluble salts are selected from the group consisting of alkali metal salts, ammonium salts, and alkali earth metal salts.
10. The process of claim 9 wherein the water-soluble salts are selected from the group consisting of sodium formate and sodium chloride.
11. The process of claim 1 wherein the polymer containing vinylamine groups arc is obtained by hydrolysis of a homo or a copolymer of N-vinylformamide.
12. (canceled)
13. The process of claim 2 wherein no more than three parts by weight of water are added to one part by weight of the feed.
14. The process of claim 2 wherein the ultrafiltration unit comprises vibratory shear membranes.
15. The process of claim 2 wherein the ultrafiltration unit comprises vibratory shear membranes having a molecular weight cut off of at least 300.
16. The process of claim 2 wherein the membranes of the ultrafiltration unit have a molecular weight cut off of at least 2,000.
17. The process of claim 2 wherein the membranes of the ultrafiltration unit have a molecular cut off of at least 4,000.
18. The process of claim 2 wherein the membranes of the ultrafiltration unit have a molecular weight cut off of from 9,000 to 100,000.
19. The process of claim 2 wherein the water-soluble salts are selected from the group consisting of alkali metal salts, ammonium salts, and alkali earth metal salts.
20. The process of claim 19 wherein the water-soluble salts are selected from the group consisting of sodium formate and sodium chloride.
21. The process of claim 2 wherein the polymer containing vinylamine groups is obtained by hydrolysis of a homo or a copolymer of N-vinylformamide.
22. A multicomponent superabsorbent polymer comprising a basic water-absorbing resin prepared according to the method of claim 1.
23. A multicomponent superabsorbent polymer comprising a basic water-absorbing resin prepared according to the method of claim 2.
24. A polymer containing vinylamine groups prepared by the method of claim 1.
25. A polymer containing vinylamine groups prepared by the method of claim 2.
Ref US6716311I: [content unavailable]