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 .
Italian Patent 580939 could not be obtained from the Italian Patent Office nor could be obtained from any other source.
Claim Rejections - 35 USC § 103
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 1-6 and 8 rejected under 35 U.S.C. 103 as being unpatentable over Brown 2937164 in view of RU2351610 and Tsukada 2010/0330319.
Brown exemplifies (#1) polymerizing butadiene/acrylonitrile/methacrylic acid terpolymer (ie applicant’s carboxyl group containing nitrile rubber) in latex form. The polymerization is carried out at a pH of 4 (col 4 line 72,73). Presumably, the pH would still be <5 at the conclusion of the polymerization. Brown then adds an aqueous solution of CaCl2 to isolate the liquid polymer (col 5 line 1-3). CaCl2 is applicant’s preferred salting out agent (see applicant’s table 1). Brown does not report to what degree the CaCl2 solution raises the pH of the mixture and therefore whether or not applicant’s “pH<5” is met.
RU2351610 (abstract) teaches coagulating rubber latex at a pH of 2.5-6.9. Example 6 shows coagulating nitrile rubber with CaCl2 while keeping the pH at 2.5 (see table) by pre-acidifying the rubber latex with sulfuric acid prior to adding the CaCl2. This differs from applicant’s claimed method in that the CaCl2 is not provided as solution of CCl2 with the acid (ie “controlling the pH of the salting out agent solution”). Tsukada (paragraph 139) similarly coagulates nitrile rubber at a pH of 1-4 with metal compounds such as CaCl2 (paragraph 137). Tsukada (paragraph 141) teaches the pH can be adjusted (eg by adding sulfuric acid) to the desired level by:
adjusting the pH of the nitrile rubber latex
Or
(2) adjusting the pH of the coagulating agent solution and adjusting the pH of the nitrile rubber latex
Or
(3) combining the rubber latex, the coagulating solution and the sulfuric acid solution
It would have been obvious to add sulfuric acid in Brown’s process by any of these three processes in order to keep the pH low during salting out. Each would wind up with the same final product.
The RU2351610 method corresponds to (1) above. Applicant’s claimed method corresponds to (2) above.
It would have been obvious to ensure Brown’s coagulation step occurs at a pH of 2-5 by adding sufficient acid to the CaCl2 solution.
In regards to applicant’s dependent claims:
Brown’s nitrile rubber is a 55/25/20 Bd/AN/MAA rubber – meeting applicant’s claims 2-4.
Brown does not state the quantity of CaCl2 added, but RU2351610 exemplifies (#6) 23kg CaCl2 per ton of nitrile rubber. Assuming a metric ton (ie 1000kg), the amount of CaCl2/rubber would be:
23kg CaCl2
--------------------- = 2.3parts CaCl2 per 100 parts rubber – meeting claim 6.
1000kg rubber
In regards to applicant’s claim 8, the concentration of the metal salt solution (whether provided as a 10% aqueous solution or as a 15% aqueous solution) would appear to have no effect on the process as long as the amount of metal salt provided is the same.
It would have been obvious to carry out Brown’s process with slightly more of a less concentrated solution of CaCl2 to achieve the same result.
Claims 1-5 and 8 rejected under 35 U.S.C. 103 as being unpatentable over Brown 2937164 in view of CA3047711.
Brown exemplifies (#1) polymerizing butadiene/acrylonitrile/methacrylic acid terpolymer (ie applicant’s carboxyl group containing nitrile rubber) in latex form. The polymerization is carried out at a pH of 4 (col 4 line 72,73). Presumably, the pH would still be <5 at the conclusion of the polymerization. Brown then adds an aqueous solution of CaCl2 to isolate the liquid polymer (col 5 line 1-3). CaCl2 is applicant’s preferred salting out agent (see applicant’s table 1). Brown does not report to what degree the CaCl2 solution raises the pH of the mixture and therefore whether or not applicant’s “pH<5” is met.
CA3047711 (paragraph 46,47) teaches that coagulation of butadiene/acrylonitrile/methacrylic acid terpolymers with salts should be conducted at a pH of 2-5. This is done by adding inorganic acid to the mixture or to the inorganic salt solution (paragraph 47). CA3047711 (paragraph 34) recognizes a high pH increases unfavorably increases the viscosity and results in high levels of residual metal (paragraph 50).
It would have been obvious ensure Brown’s coagulation step occurs at a pH of 2-5 by adding sufficient acid to the CaCl2 solution.
In regards to applicant’s dependent claims:
Brown’s nitrile rubber is a 55/25/20 Bd/AN/MAA rubber – meeting applicant’s claims 2-4.
In regards to applicant’s claim 8, the concentration of the metal salt solution (whether provided as a 10% aqueous solution or as a 15% aqueous solution) would appear to have no effect on the process as long as the amount of metal salt provided is the same. This especially true as the carboxylated nitrile rubber itself is in aqueous latex form. CA3047711 (page 35 line 3) shows similar salting out processes for carboxylated nitrile rubbers where the salting out is carried out with a 5% solution of the salt.
It would have been obvious to carry out Brown’s process with slightly more of a less concentrated solution of CaCl2 to achieve the same result.
Claim 6 rejected under 35 U.S.C. 103 as being unpatentable over Brown 2937164 in view of CA3047711 in further view of Ohishi 3790646.
Brown/CA3047711 apply as explained above.
Brown does not state the quantity of CaCl2 added.
Ohishi is also directed to carboxylic functional nitrile rubbers (abstract; table 2). Ohishi (col 2 line 72; table 8) teaches 1-5% salts such as CaCl2 based on the rubber content for coagulation purposes.
It would have been obvious to operate Brown’s process such that 1-5% CaCl2 is provided to his carboxylated nitrile rubber in order to successfully isolate the rubber.
Claim 6 rejected under 35 U.S.C. 103 as being unpatentable over Brown 2937164 in view of CA3047711 in further view of JP2003160611 or JP2004143323.
Brown/CA3047711 apply as explained above.
Brown does not state the quantity of CaCl2 added.
The two Japanese references coagulate nitrile rubber with CaCl2.
JP2003160611 (paragraph 57) provides a 5% CaCl2 soln at a rate of 50kg/hr and 400kg/hr of a 20wt% nitrile rubber latex. The amount of CaCl2 would be:
0.05 x 50kg CaCl2/hr
------------------------------- = 3 parts CaCl2 100 parts nitrile rubber
0.2 x 400kg rubber/hr
JP2004143323 (paragraph 22) combines sufficient CaCl2 coagulant solution with nitrile rubber latex to result in a 10wt% rubber concentration. The starting rubber latex would be approximately 70 parts rubber per 200 parts water. The coagulant soln is 4 parts CaCl2 in 1000 parts water. To arrive at the 10% rubber concentration, the added coagulant must have been 2 parts CaCl2 in 500 parts water. Therefore, the ratio of CaCl2/rubber is 2 parts CaCl2 per 70 parts rubber or 2.8 parts per 100.
Applicant’s claimed 1-10 parts CaCl2 encompasses conventional amounts of CaCl2 for 100 parts nitrile rubber.
Applicant's arguments filed 4/17/25 have been fully considered but they are not persuasive.
Applicant argues that CA 3047711’s only teaches controlling pH by adding sulfuric acid to the rubber – not to the solution of the salting out agent as is done by applicant.
This is not true. The last line of paragraph 47 clearly states “inorganic acid such as sulfuric acid is added to the aqueous solution”. The previous sentence states “the pH of the aqueous solution may be lowered and then the solution may be added”.
Applicant argues that CA 3047711’s teachings regarding pH are only applicable to sodium chloride – not the divalent metal salts now required.
This is not convincing, CA 3047711’s paragraph 46 is not limited to sodium salts as “sodium” is never mentioned in this paragraph. This paragraph simply refers to “a coagulant”. The following paragraph states “the coagulant is not particularly limited”. The fact that this secondary reference prefers sodium salts does not infer the reference’s teachings are inapplicable to other common metal salt coagulants. Paragraph 51 states that the teachings regarding the method of controlling the pH when sodium salt is used – “is not particularly limited to such a method”.
It is reasonable to infer any residual metal in the final product would be unfavorable – whether sodium or calcium. Applicant provides no chemical explanation why the pH control would not have a similar effect when using CaCl2. The Tsukada reference supports the examiner’s position given Tsukada (paragraph 137) lists numerous coagulating metal salts including NaCl and CaCl2 and is also concerned with pH during coagulation of the nitrile rubber (paragraph 141).
Applicant’s argument that liquid rubbers have no need to reduce the amount of metal salts in the final product and therefore are not washed with water is unsupported by anything of record. In fact, applicant’s example (paragraph 63 of spec) conducts washings with water.
Arguments that teachings directed to solid carboxyl containing nitrile rubbers are not applicable to liquid carboxyl nitrile rubbers are not convincing.
Applicant provides no technical reasoning why isolating a liquid carboxyl nitrile rubber from its latex is substantially different from isolating a solid carboxyl nitrile rubber from its latex. The difference between the solid and liquid form is merely molecular weight.
Applicant’s argument that CA3047711’s pH during crosslinking is different from the pH during salting out is meritless.
CA3047711’s pH requirement is during its coagulation step. Controlling the pH at this step keeps the viscosity low enough for later crosslinking. Coincidentally, the primary reference (Brown) also intends for later crosslinking.
Applicant argues that RU2351610 teaches that adding the acid to the rubber latex is superior to adding the acid to the salting out solution.
While this is true, RU2351610 does recognize adding the acid to the salting out solution was known – although inferior. Tsukada (paragraph 141) teaches both methods are effective to control pH during coagulation. Collectively, RU2351619 and Tsukada can be said to teach the importance of the precise pH range during coagulation and that the pH controlling acid can be added to the rubber directly, the coagulating salt solution or as a separate addition. It appears applicant has merely chosen the least favorable (though still) obvious route.
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.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to DAVID J BUTTNER whose telephone number is (571)272-1084. The examiner can normally be reached M-F 9-3pm.
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/DAVID J BUTTNER/Primary Examiner, Art Unit 1765 3/3/26