DETAILED ACTION
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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.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 01/19/2026 has been entered.
Response to Amendment
In response to the amendment received on 01/19/2026:
claims 1, 3-4 and 7-21 are currently pending
claims 10-16 and 19-20 are withdrawn from consideration
claim 1 is amended
previously presented claim objection is withdrawn in light of the amendment to the claim
new prior art grounds of rejection applying Muller, Letteman, Groza and Stocco are presented herein
Claims 1, 3-4, 7-9 and 17-18 are rejected under 35 U.S.C. 103 as being unpatentable over Muller et al. (US 9255032 B2), hereinafter referred to as MULLER, in view of Lettkeman et al. (WO 2006138277 A2), hereinafter referred to as LETTKEMAN, and Groza et al. (US 20120090508 A1), hereinafter referred to as GROZA.
Regarding claim 1, MULLER teaches a gypsum set accelerator (Col. 1, lines 65-66: a setting accelerator suitable for binders based on calcium sulfate), wherein the gypsum set accelerator is a dry-milled mixture comprising calcium sulfate dihydrate co-ground with one or more of the following: a polycarboxylic ether (PCE) (Col. 3, lines 5-6: gypsum together with at least one polycarboxylate is subjected to a dry grinding; and Col. 8, line 46: polycarboxylate, for example, a polycarboxylate ether) and/or sulfonated melamine polycondensate (SMP),
wherein the gypsum set accelerator comprises from 0.1 to 5 parts by weight of the PCE and/or SMP per 100 parts by weight of calcium sulfate dihydrate (Col. 4, lines 31-33: the polycarboxylate can be present in an amount of a fraction of 0.2-1 wt.% with respect to the gypsum).
But MULLER fails to explicitly teach wherein the polycarboxylate ether is a co-polymer composed of oxyalkylene-alkyl ether, maleic acid and acrylic acid repeating units, and having a molecular weight in the range from 20000 to 80000 Daltons.
However, LETTKEMAN teaches the gypsum slurry made using water, calcined gypsum a polycarboxylate dispersant and a modifier (see LETTKEMAN at paragraph 1, p. 7); and that a number of polycarboxylate dispersants, particularly polycarboxylic ethers, are preferred types of dispersants (see LETTKEMAN at last paragraph, p. 7). LETTKEMAN teaches polycarboxylate polymer comprising an olefinic unsaturated mono-carboxylic acid repeating unit (see LETTKEMAN at second paragraph, p. 8), the polyether group of Formula II containing multiple alkyl groups, including at least two different alkyl groups, connected by oxygen atoms (see LETTKEMAN at Formula II, p. 8 and second paragraph, p. 9). LETTKEMAN also discloses the polymer wherein both acrylic and maleic acid repeating units are present (see LETTKEMAN at first paragraph, p. 11). LETTKEMAN teaches the molecular weight from about 2000 to about 60000 Daltons (see LETTKEMAN at second paragraph, p. 10). Additionally, LETTKEMAN discloses that the ratio of the acid-containing repeating units to the polyether-containing repeating units is directly related to the charge density; preferably the charge density of the co-polymer is in the range of about 300 to about 3000 µequiv. charges/g co-polymer (see LETTKEMAN at second paragraph, p. 13). LETTKEMAN also teaches that charge density of the co-polymer effects set times (see LETTKEMAN at last paragraph, p. 13). Finally, LETTKEMAN teaches that the disclosed dispersants/co-polymers are particularly well-suited for use with gypsum (see LETTKEMAN at last paragraph, p. 12).
Both MULLER’s and LETTKEMAN’s disclosures are from the same field of endeavor, and drawn to the compositions containing gypsum and polycarboxylate co-polymers, wherein the polycarboxylate is used to effect set times (see MULLER at Abstract, and LETTKEMAN at last paragraph, p. 13). According to MPEP § 2144.06(I), "It is prima facie obvious to combine two compositions each of which is taught by the prior art to be useful for the same purpose, in order to form a third composition to be used for the very same purpose.... [T]he idea of combining them flows logically from their having been individually taught in the prior art." In re Kerkhoven, 626 F.2d 846, 850, 205 USPQ 1069, 1072 (CCPA 1980).
Therefore, it would have been obvious to one of ordinary skill in the art prior to the effective filing date of the claimed invention to have modified the composition of MULLER by utilizing the polycarboxylate ether co-polymer composed of oxyalkylene-alkyl ether, maleic acid and acrylic acid repeating units, having a molecular weight in the range from 20000 to 60000 Daltons, and having the charge density in the range of about 300 to about 3000 µequiv. charges/g co-polymer, as disclosed by LETTKEMAN, because LETTKEMAN explicitly teaches that the disclosed dispersants/co-polymers are particularly well-suited for use with gypsum (see LETTKEMAN at last paragraph, p. 12). The rationale for such modification would have been combining prior art elements according to known methods to yield predictable results (see MPEP §2143 (I), rationale example (A)).
MULLER as modified by LETTKEMAN teaches the gypsum set accelerator of claim 1, but is silent with respect to the gypsum set accelerator being an aged gypsum set accelerator. However, aging set accelerators is known in the art. MULLER describes the previously disclosed accelerator with an improved storage stability (see MULLER at Col. 1, lines 50-52). Furthermore, LETTKEMAN discloses that the dispersant attaches itself to the calcium sulfate (see LETTKEMAN at paragraph 3, p. 7), and that it is believed that the acid repeating units bind to the hemihydrate crystals while the long chains perform the dispersing function (see LETTKEMAN at paragraph 2, p. 12). The protective nature of additives binding to calcium sulfate is known in the art, as evidenced from disclosure of GROZA disclosing gypsum accelerator and describing that it is believed that, upon grinding, the desired additives become affixed to the freshly generated outer surface of the calcium sulfate dihydrate, providing at least a partial coating on the calcium sulfate dihydrate; it also is believed that the additives strongly and rapidly adsorb on active sites of the calcium sulfate dihydrate surface of the accelerator, where unwanted recrystallization can otherwise occur; and as a result, it also is believed that by adsorbing on such active sites, the additives protect the size and shape of the active sites to prevent gypsum recrystallization of the ground gypsum upon exposure to heat and/or moisture (see GROZA at paragraph [0024]).
Therefore, it would have been obvious to one of ordinary skill in the art that by attaching itself to the calcium sulfate, the dispersant of LETTEMAN would protect the size and shape of the active sites to prevent gypsum recrystallization of the ground gypsum upon exposure to heat and/or moisture, based on the disclosure of GROZA (see GROZA at paragraph [0024]), and thus, resulting in an accelerator with increased stability. Moreover, one of ordinary skill in the art would have recognized the potential benefit of aging a set accelerator of MULLER for the benefit of storing a set accelerator. See MPEP §2143 (I)(G): “Known work in one field of endeavor may prompt variations of it for use in either the same field or a different one based on design incentives or other market forces if the variations are predictable to one of ordinary skill in the art”.
While MULLER as modified by LETTKEMAN is silent with respect to the gypsum set accelerator retaining set-accelerating efficiency when stored under humid conditions with humidity of 70% or higher, MULLER as modified by LETTKEMAN discloses all compositional limitations of a gypsum set accelerator as set forth. Accordingly, the set accelerator of MULLER as modified by LETTKEMAN would necessarily comprise the claimed property such retaining set-accelerating efficiency when stored under humid conditions with humidity of 70% or higher. See MPEP §2112.01(I): “where the claimed and prior art products are identical or substantially identical in structure or composition, or are produced by identical or substantially identical processes, a prima facie case of either anticipation or obviousness has been established. In re Best”.
Regarding claim 3, MULLER as modified by LETTKEMAN teaches the gypsum set accelerator of claim 1, wherein the gypsum set accelerator comprises from 1 to 2 parts by weight of the PCE and/or SMP per 100 parts by weight of calcium sulfate dihydrate (see MULLER at Col. 4, lines 31-33: the polycarboxylate can be present in an amount of a fraction of 0.2-1 wt.% with respect to the gypsum). MULLER teaches range which overlaps and renders obvious the claimed range. In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim. See MPEP §2144.05(I).
Regarding claim 4, MULLER as modified by LETTKEMAN teaches the gypsum set accelerator of claim 1, wherein calcium sulfate dihydrate is sourced as mined gypsum or synthetic gypsum (see MULLER at Col. 10, line 14: REA gypsum from Knauf/synthetic gypsum).
Regarding claim 7, MULLER as modified by LETTKEMAN teaches the gypsum set accelerator of claim 1, wherein the co-polymer has a charge density in the range from about 300 to about 3000 µequiv. charges/g co-polymer (see LETTKEMAN at second paragraph, p. 13). LETTKEMAN teaches range identical to the claimed range.
Regarding claim 8, MULLER as modified by LETTKEMAN teaches the gypsum set accelerator of claim 1, wherein the co-polymer has a charge density in the range from about 600 to about 2000 µequiv. charges/g co-polymer (see LETTKEMAN at second paragraph, p. 13: more preferably, the charge density of the co-polymer is the range from about 600 to about 2000 µequiv. charges/g co-polymer). LETTKEMAN teaches range identical to the claimed range.
Regarding claim 9, MULLER as modified by LETTKEMAN teaches the gypsum set accelerator of claim 1, wherein the gypsum set accelerator does not contain sugar or starch (see MULLER at Col. 1, lines 65-67: making a setting accelerator suitable for binders based on calcium sulfate, the method comprising subjecting gypsum together with polycarboxylate to a dry grinding). MULLER does not disclose sugar or starch as a constituent of the setting accelerator.
Regarding claim 17, MULLER as modified by LETTKEMAN teaches a gypsum slurry comprising at least calcined gypsum, water and gypsum set accelerator of claim 1 (see MULLER at Col. 8, lines 59-61: a binder composition containing a binder based on calcium sulfate, for example stucco, as well as a setting accelerator; and line 65: the binder composition contains water).
Regarding claim 18, MULLER as modified by LETTKEMAN teaches a gypsum slurry of claim 17, wherein the gypsum slurry is further characterized by one or more of the following features:
the gypsum set accelerator is in an amount in the range from about 0.1 wt% to about 5 wt% calculated based on the weight of calcined gypsum (see MULLER at Col. 8, lines 62-64: the setting accelerator is present in a fraction of 0.00005-5 wt.%). MULLER teaches range which overlaps with the claimed range;
a water/stucco ratio is in the range from about 0.4 to about 1.5 (see MULLER at Col. 8, lines 66-67: a weight ratio of water to binder lies in the range of 0.4-0.8). MULLER teaches range which is within the claimed range.
Claim 21 is rejected under 35 U.S.C. 103 as being unpatentable over MULLER in view of LETTKEMAN as applied to claim 1 above, and further in view of over Stocco et al. (US 20080160340 A1), hereinafter referred to as STOCCO.
Regarding claim 21, MULLER as modified by LETTKEMAN teaches the gypsum set accelerator of claim 1, but fails to explicitly teach wherein the gypsum set accelerator comprises SMP.
However, STOCCO discloses a gypsum slurry that includes calcium sulfate hemihydrate and polycarboxylate dispersant (see STOCCO at paragraph [0015]). STOCCO also discloses that reduction in the amount of water used to make the slurry is achieved by the addition of a dispersant, such as a polycarboxylate; the dispersant attaches itself to the calcium sulfate, then charged groups on the backbone and the side chains on the branches of the polymer repel each other, causing the gypsum particles to spread out and flow easily (see STOCCO at paragraph [0033]). STOCCO teaches that known dispersants include polycarboxylates, sulfonated melamine or naphthalene sulfonate (see STOCCO at paragraph [0056]). Thus, based on the disclosure of STOCCO, one of ordinary skill in the art would have recognized polycarboxylates and sulfonated melamine as art-recognized equivalents known for the same purpose (see MPEP §2144.06).
According to MPEP §2143.(I)(example rationale (G)): “Some teaching, suggestion, or motivation in the prior art that would have led one of ordinary skill to modify the prior art reference or to combine prior art reference teachings to arrive at the claimed invention”. Therefore, one of ordinary skill in the art would have anticipated success when modifying the set accelerator of MULLER as modified by LETTKEMAN by including sulfonated melamine based on teachings of STOCCO disclosing the dispersants including the art-recognized equivalents such as polycarboxylate and sulfonated melamine.
Response to Arguments
Applicant's arguments filed on 01/29/2026 have been fully considered but they are not persuasive.
Applicant argues that neither MULLER nor LETTKEMAN discloses or suggests the aged gypsum set accelerator having features set forth in claim 1 such as set accelerator being aged set accelerator, which retains set-accelerating efficiency when stored under humid conditions with humidity of 70% or higher (see Remarks spanning paragraphs on page 8).
However, the examiner respectfully disagrees for the following reasons. As was discussed in the rejection of claim 1 above, MULLER discloses a setting accelerator suitable for binders based on calcium sulfate (see MULLER at Col. 1, lines 65-66), wherein gypsum together with at least one polycarboxylate is subjected to a dry grinding (see MULLER at Col. 3, lines 5-6). MULLER also discloses that significantly less caking or sticking to the grinding bodies occurs when using polycarboxylates as additive during dry grinding of gypsum, as compared to a blank sample without additive; thus, the production capacity of the mill or the amount of gypsum ground per unit of time can be significantly increased for the same mill performance; as a result, the expense for the cleaning of the mill can be reduced, which in turn decreases the wear and tear on the mill or the grinding bodies; furthermore, the possibility exists of achieving a greater fineness of the ground product when using polycarboxylates (see MULLER at Col. 2, lines 39-49). MULLER further discloses that the setting accelerator can be used in pure form or together with at least one other additive; the additive used can be, e.g., a flow agent, for exanple a polycarboxylate such as a polycarboxylate ether; the polycarboxylate can be as defined above and it can improve the flow properties of binders based on calcium sulfate; the polycarboxylate used as the additive can be different from or the same as the polycarboxylate used in the dry grinding process (see MULLER at Col. 8, lines 38-51). Therefore, based on the disclosure of MULLER, one of ordinary skill in the art would have recognized that the polycarboxylate ether used in the set accelerator of MULLER can also be utilized as a flow agent. Since LETTKEMAN discloses the polycarboxylate dispersant useful for improving fluidity (see LETTKEMAN at paragraph 4, p. 7), and that the disclosed dispersants are well-suited for use with gypsum because it is believed that the acid repeating units bind to the hemihydrate crystals while the long chains perform the dispersing function (see LETTKEMAN at paragraph 2, p. 12), one of ordinary skill in the art would have anticipated success when utilizing the polycarboxylate dispersants in the set accelerator of MULLER.
MULLER as modified by LETTKEMAN discloses the gypsum set accelerator comprising components as set forth in claim 1. MPEP §2112(I) states: “"[T]he discovery of a previously unappreciated property of a prior art composition, or of a scientific explanation for the prior art’s functioning, does not render the old composition patentably new to the discoverer." Atlas Powder Co. v. IRECO Inc., 190 F.3d 1342, 1347, 51 USPQ2d 1943, 1947 (Fed. Cir. 1999). Thus the claiming of a new use, new function or unknown property which is inherently present in the prior art does not necessarily make the claim patentable. In re Best, 562 F.2d 1252, 1254, 195 USPQ 430, 433 (CCPA 1977)”. Furthermore, the protective nature of additives binding to calcium sulfate is known in the art, as evidenced from disclosure of GROZA disclosing gypsum accelerator and describing that it is believed that, upon grinding, the desired additives become affixed to the freshly generated outer surface of the calcium sulfate dihydrate; and that the additives protect the size and shape of the active sites to prevent gypsum recrystallization of the ground gypsum upon exposure to heat and/or moisture (see GROZA at paragraph [0024]). Therefore, it would have been obvious to one of ordinary skill in the art that by attaching itself to the calcium sulfate, the dispersant of LETTEMAN would protect the size and shape of the active sites to prevent gypsum recrystallization of the ground gypsum upon exposure to heat and/or moisture, based on the disclosure of GROZA (see GROZA at paragraph [0024]), and thus, resulting in an accelerator with increased stability. Moreover, one of ordinary skill in the art would have recognized the potential benefit of aging a set accelerator of MULLER for the benefit of storing a set accelerator.
In response to Applicant argument that LETTKEMAN teaches that polycarboxylates may retard a setting reaction, and thus, discouraging one of ordinary skill in the art from utilizing a co-polymer of LETTKEMAN, it is noted that MPEP §2123(II) states: “Disclosed examples and preferred embodiments do not constitute a teaching away from a broader disclosure or nonpreferred embodiments. In re Susi, 440 F.2d 442, 169 USPQ 423 (CCPA 1971). "A known or obvious composition does not become patentable simply because it has been described as somewhat inferior to some other product for the same use." In re Gurley, 27 F.3d 551, 554, 31 USPQ2d 1130, 1132 (Fed. Cir. 1994)”. Thus, based on LETTKEMAN’s disclosure that the disclosed dispersants are well-suited for use with gypsum (see LETTKEMAN at paragraph 2, p. 12), one of ordinary skill in the art would have anticipated success when utilizing the polycarboxylate dispersants in the set accelerator of MULLER.
Applicant argues that the gypsum set accelerator according to claim 1 and its dependent claims retain its set-setting efficacy when stored under humid conditions, and that MULLER does not disclose aged set accelerators (see Remarks received on 01/19/2026 at last paragraph on page 9).
However, the examiner respectfully disagrees for the following reasons. It is noted, that MULLER’s disclosure regarding storage stability of setting accelerators presented in Office Action mailed on 10/23/2025 (see MULLER at Col. 1, lines 50-52) was presented as an evidence that aged accelerators are known in the art. As was discussed in the rejection of claim 1 above, MULLER as modified by LETTEMAN disclosed a gypsum setting accelerator obtained by subjecting gypsum with at least one polycarboxylate to a dry grinding (see MULLER at Col. 3, lines 5-6). Moreover, the features of polycarboxylate of LETTEMAN read on limitations of claimed PCE. Thus, one of ordinary skill in the art would have anticipated the setting accelerator of MULLER as modified by LETTEMAN to have properties and functions identical to the ones claimed by the Applicant (see MPEP §2112.01(I): “Where the claimed and prior art products are identical or substantially identical in structure or composition, or are produced by identical or substantially identical processes, a prima facie case of either anticipation or obviousness has been established. In re Best, 562 F.2d 1252, 1255, 195 USPQ 430, 433 (CCPA 1977)”). Moreover, according to MPEP §2112(I): “the claiming of a new use, new function or unknown property which is inherently present in the prior art does not necessarily make the claim patentable. In re Best, 562 F.2d 1252, 1254, 195 USPQ 430, 433 (CCPA 1977)”. Therefore, while cited prior art is silent with respect to the stability of disclosed composition, it is presumed that the setting accelerator of MULLER as modified by LETTEMAN is capable of being an aged accelerator retaining set-accelerating efficiency.
Applicant argues that there is no reason for a person of skill to believe that PCE and/or SMP of STOCCO may be suitable in a dry-milled mixture with calcium sulfate dihydrate wherein no dispersion in water takes place (see Remarks received on 01/19/2026 spanning paragraphs on page 10).
However, the examiner respectfully disagrees for the following reasons. As was discussed in the rejection of claim 21 above, STOCCO discloses that reduction in the amount of water used to make the slurry is achieved by the addition of a dispersant, such as a polycarboxylate; the dispersant attaches itself to the calcium sulfate, then charged groups on the backbone and the side chains on the branches of the polymer repel each other, causing the gypsum particles to spread out and flow easily (see STOCCO at paragraph [0033]), and that known dispersants include polycarboxylates, sulfonated melamine or naphthalene sulfonate (see STOCCO at paragraph [0056]). Aforementioned disclosure of GROZA describes gypsum accelerator and that, upon grinding, the desired additives become affixed to the freshly generated outer surface of the calcium sulfate dihydrate; it also is believed that the additives strongly and rapidly adsorb on active sites of the calcium sulfate dihydrate surface of the accelerator, where unwanted recrystallization can otherwise occur; and as a result, it also is believed that by adsorbing on such active sites, the additives protect the size and shape of the active sites to prevent gypsum recrystallization of the ground gypsum upon exposure to heat and/or moisture (see GROZA at paragraph [0024]). Thus, based on teaching of STOCCO describing that dispersant attaches itself to the calcium sulfate and disclosure of GROZA describing the additives protecting the size and shape of the active sites to prevent gypsum recrystallization of the ground gypsum upon exposure to heat and/or moisture, one of ordinary skill in the art would have anticipated success when substituting the polycarboxylates with any of the dispersants disclosed by STOCCO, including sulfonated melamine, as an additive in a setting accelerant of MULLER.
Therefore, the rejection of claims as being unpatentable over MULLER in view of LETTEMAN and STOCCO is maintained.
Conclusion
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/A.A.K./Examiner, Art Unit 1731
/ANTHONY J GREEN/Primary Examiner, Art Unit 1731