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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.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 08 January 2026 has been entered.
Response to Amendment
Applicant’s amendment filed on 07 January 2026 is acknowledged. It is acknowledged that claims 1 and 5 have been amended by Applicant. Per the amendments, the 35 U.S.C. 112 rejections of claims 1-18 and 21-22 have been withdrawn.
Response to Arguments
Applicant’s arguments with respect to claims 1 and 5 have been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument.
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 1-8, 10-18, and 22 are rejected under 35 U.S.C. 103 as being unpatentable over Beals (US-3627746-A) in view of Erchak (US-3282911-A).
Regarding Claim 1, Beals discloses a process for reducing low molecular weight oligomers and wax build-up (a method for defouling; see Col. 1 Lines 29-30) in one or more recycle coolers in a high-pressure olefin polymerization process (a series of recycle coolers in a high-pressure polyethylene system; see Col. 1 Lines 29-31), the recycle coolers having (a) passage(s) for liquid cooling medium (“the cooling media circulating through the shell side”; see Col. 2 Lines 8-9 and “cooling water, for example, may be used as the cooling media”; see Col. 1 Lines 73-74) and (a) passage(s) for fluid to be cooled (recycle gases passing through the tubes; see Col. 2 Lines 7-8), the process comprising the steps of:
a) heating the liquid cooling medium of one or more recycle coolers to a temperature of more than 50oC to provide heated cooling medium (steam may be circulated or introduced; see e.g. Col. 2 Line 12; It is understood by a person of ordinary skill in the art that steam is the product of heating water to a temperature of above 50 oC);
b) heating the one or more recycle coolers by introducing the heated cooling medium into the passage(s) for the liquid cooling medium (“steam may be circulated or introduced to the shell side of the heat exchanger in place of the cooling media”; see Col. 2 Lines 11-13 and “heat the cooler by draining the cooler 13 of the heat exchange media and introducing steam”; see Col. 2 Lines 27-29);
c) heating a gas stream to a temperature in the range of 70 to 250oC (operated with maximum heating… to maintain the high-pressure separator 11 gas temperature at about 350 oF to 450 oF; see e.g. Col. 2 Lines 17-20);
d) introducing the heated gas stream into the one or more heated recycle coolers through the passage(s) for the fluid to be cooled (cooling of the recycled ethylene feed; see Col. 1 Lines 41-42; and “recycle gases passing through the tubes; see Col. 2 Lines 7-8; and Fig. 1 Parts 11, 12, and 13);
e) softening low molecular weight oligomers and wax build-up on the inner walls of the passage(s) for the fluid to be cooled of the one or more heated recycle coolers by means of the heated gas stream (The polymer which has collected in cooler 13 is removed and collected in knockout pot 22; see Col. 2 Lines 31-32);
f) removing the softened low molecular weight oligomers and wax build-up from the passage(s) for the fluid to be cooled of the one or more heated recycle coolers with the heated gas stream (The polymer which has collected in cooler 13 is removed and collected in knockout pot 22; see Col. 2 Lines 31-32), wherein the gas stream is separated from a gas stream discharged from a primary compressor of the high pressure polymerization process (the ethylene feed is circulated by the compressor through the reactor in the polyethylene system and into the reactor effluent stream 10 and into the high-pressure separator 11; see Col. 2 Lines 14-16; and “…into a high-pressure separator 11. The gases are removed by line 12 for recycling while the polyethylene is removed by line 8”; see Col. 1 Lines 58-61).
Regarding the limitation claiming “softening low molecular weight oligomers and wax build-up on the inner walls of the passage(s) for the fluid to be cooled of the one or more heated recycle coolers by means of the heated gas stream”, this step is merely a product of the previous steps. Therefore, because Beals discloses steps a-d, then step e will inherently occur. Additionally, Beals discloses the removal of polymer build up via a heated gas stream, which fully indicates that the wax was softened in the process.
Regarding the claimed temperature range of the gas stream, MPEP 2144.05.I states that in the case where the claimed ranges overlap or lie inside ranges disclosed by the prior art, a prima facie case of obviousness exists.
Regarding the limitation claiming that the heated cooling medium is a heated liquid cooling medium, this would have been an obvious modification to a person of ordinary skill in the art before the effective filing date of the claimed invention. KSR Rationale B (see MPEP 2141) states that it is obvious to perform “simple substitution of one known element for another to obtain predictable results”. Therefore, because there are no new or unexpected results from using a heated liquid cooling medium, such as heated cooling water, instead of using steam, it would have been obvious to a person of ordinary skill in the art prior to the effective filing date of the claimed invention to make such a substitution. Further, this is a matter of optimization through routine experimentation. Specifically, whether steam is used as the heated cooling medium or heated cooling water is used as the heated cooling medium depends only on the temperature that the cooling medium is heated to. The cooling medium undergoes the same process, but in one scenario it is heated to a higher temperature than in the other scenario. Generally, differences in concentration or temperature will not support the patentability of subject matter encompassed by the prior art unless there is evidence indicating such concentration or temperature is critical. “[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation.” In reAller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955). In this case, there is not evidence indicating that heating the cooling medium to a temperature below the boiling point, resulting in a heated liquid cooling medium, is critical or advantageous over heating the cooling medium to the boiling point, resulting in a heated cooling medium in the vapor phase. Therefore, this modification would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention.
Beals does not explicitly teach that the stream is not manipulated after being separated and before introduction to the recycle coolers. However, Erchak discloses wherein the pressure of the gas stream is not manipulated before introducing into the one or more recycle coolers (The ethylene recycle stream… comes directly from the high-pressure separator at elevated temperatures and contacts the surfaces in condensing zones 20 and 22; see Col. 2 Lines 57-61).
Beals and Erchak are both considered to be analogous to the claimed invention because they are in the same field of treatment of polymerization processes. Therefore, it would have been obvious to a person of ordinary skill in the art prior to the effective filing date of the claimed invention to have modified Beals by incorporating the teachings of Erchak and avoid pressure manipulation of the gas stream in between the separator and the recycle coolers. Doing so enables the gas to melt the deposited constituents and carry them in the stream from the cooler/condenser (see Erchak Col. 2 Lines 62-63).
Regarding Claim 2, Beals discloses the process according to claim 1, wherein the gas stream is heated to a temperature in the range of 70 to 250°C (operated with maximum heating… to maintain the high-pressure separator 11 gas temperature at about 350 oF to 450 oF; see e.g. Col. 2 Lines 17-20). MPEP 2144.05.I states that in the case where the claimed ranges overlap or lie inside ranges disclosed by the prior art, a prima facie case of obviousness exists.
Regarding the limitation claiming, “depending on the amount of reducing low molecular weight oligomers and wax build-up in one or more recycle coolers” merely describes a relationship or correlation between the temperature and amount of build-up. The claim does not recite any step of measuring the build up or selecting a temperature as a function of the amount of build-up. Accordingly, the phrase is non-limiting and does not distinguish the claimed temperature range from the prior art teaching an overlapping range.
Regarding Claim 3, Beals discloses the process according to claim 1, wherein the gas stream comprises low molecular weight oligomers and wax in an amount of less than 1000 ppm, based on the total weight of the gas stream. This would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention because Beals discloses an ethylene stream used to defoul the coolers of the system, without polymerization occurring through the series of recycle coolers (see e.g. Col. 1 Lines 29-34). It is very well understood that the ethylene used in this process contains less than 1000 ppm of low molecular weight oligomers and wax, as any higher concentration risks increasing fouling, instead of decreasing it. Additionally, MPEP 2144.05.II states that “[W]here the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation”. Because such a concentration provides such effects, routinely experimenting with and coming up with a low molecular weight oligomers and wax concentration of less than 1000 ppm so as to achieve the effects of effectively defouling would have been obvious to a person of ordinary skill in the art prior to the effective filing date of the claimed invention.
Regarding Claim 4, Beals discloses the process according claim 1, wherein the gas stream is free from detectable amounts of low molecular weight oligomers and wax. As mentioned above, it would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention, and industry standard, to keep the concentration of low molecular weight oligomers and wax as low as possible in order to optimize the defouling process. It is very well understood that defouling is the most successful when the concentration of the substance causing fouling is as low as possible in the defouling stream.
Regarding Claim 5, the limitations of this claim do not exceed those of claim 3, which depends on claim 1. Please refer to the rejections of claims 1 and 3 for the associated rationale.
Regarding Claim 6, the limitations of this claim do not exceed those of claim 4. Please refer to the rejection of claim 4 for the associated rationale.
Regarding Claim 7, Beals discloses the process according to claim 5, wherein the gas stream discharged from a primary compressor (the ethylene feed is circulated by the compressor through the reactor; see Col. 2 Lines 14-16) and is heated to a temperature in the range of 70 to 250°C (operated with maximum heating… to maintain the high-pressure separator 11 gas temperature at about 350 oF to 450 oF; see e.g. Col. 2 Lines 17-20) and the heated gas stream is introduced into the one or more heated recycle coolers (see Fig. 1 Parts 10-13).
Regarding Claim 8, Beals discloses the process according to claim 7, wherein the gas stream is heated to a temperature in the range of from 70 to 250°C (operated with maximum heating… to maintain the high-pressure separator 11 gas temperature at about 350 oF to 450 oF; see e.g. Col. 2 Lines 17-20), reducing low molecular weight oligomers and wax build-up in one or more recycle coolers (This is a natural consequence that occurs after the steps laid out in the previous claims, of which are disclosed by Beals, and therefore this limitation naturally occurs in Beals’s process).
Regarding Claim 10, Beals discloses the process according to claim 1, wherein the gas stream is separated from the gas stream discharged from a primary compressor of the high-pressure polymerization process (the ethylene feed is circulated by the compressor through the reactor in the polyethylene system and into the reactor effluent stream 10 and into the high-pressure separator 11; see Col. 2 Lines 14-16; and “…into a high-pressure separator 11. The gases are removed by line 12 for recycling while the polyethylene is removed by line 8”; see Col. 1 Lines 58-61) and optionally introduced to a heating system to produce the heated gas stream (operated with maximum heating on all jacket sections to maintain the high-pressure separator 11 gas temperature; see Col. 2 Lines 17-20).
Regarding Claim 11, Beals discloses the process according to claim 10, wherein the gas stream that is separated from the gas stream discharged from the primary compressor has a pressure in the range of 100 to 300 barg (pressure in the polyethylene system is less than 10,000 psi; see Col. 2 Lines 22-24) and a temperature in the range of 50 to 150 0C (see e.g. Col. 2 Lines 32-35 and 17-20) before optionally being introduced to a heating system to produce the heated gas stream. Specifically, Beals discloses the pressure in the system staying below 10,000 psi (689.48 bar), and discloses the temperature at the inlet of the compressor being 250oF or less, and the temperature of the gas exiting the reactor, which is analogous to the optional heating system, as being between 350oF and 450oF. Beals does not specifically disclose a temperature or temperature range of the gas between the compressor and heating system, but based on the temperatures that are disclosed, it can be reasonably deduced that the temperature lays in the range of 250oF - 450oF (121.11oC – 232.22oC), the lower limit of the range likely being less, as the temperature at the inlet of the compressor is disclosed as “not exceeding about 250oF”. This temperature range, as well as the upper pressure limit of the system, overlaps with the temperature and pressure ranges as claimed in the instant application. MPEP 2144.05.I states that in the case where the claimed ranges overlap or lie inside ranges disclosed by the prior art, a prima facie case of obviousness exists.
Regarding Claim 12, Beals discloses the process according to claim 1, wherein the heated gas stream comprising the softened low molecular weight oligomers and wax build-up exiting the one or more heated recycle coolers is introduced into a separating vessel (The polymer which has collected in cooler 13 is removed and collected in knockout pot 22; see Col. 2 Lines 31-32) to separate the softened low molecular weight oligomers and wax build-up from the heated gas stream (The polymer which has collected in cooler 13 is removed and collected in knockout pot 22; see Col. 2 Lines 31-32 and Fig. 1 Part 22).
Regarding Claim 13, Beals discloses the process according to claim 1, wherein the one or more recycle coolers are situated in the high pressure recycle gas system for recycling the gas stream separated from the polyolefin stream in a high-pressure separator (the reactor effluent is introduced by line 10 into a high-pressure separator 11. The gases are removed by line 12 for recycling… In the recycle line 12 are a series of recycle coolers; see e.g. Col. 1 Lines 58-64).
Regarding Claim 14, Beals discloses the process according to claim 13, wherein the high pressure recycle gas system comprises two or more cooling steps (The cooling is done in stages through a series of recycle coolers illustrated by coolers 13, 14, and 15; see e.g. Col. 1 Lines 65-66) and the one or more recycle coolers are situated in the second or more cooling steps (The cooling is done in stages through a series of recycle coolers illustrated by coolers 13, 14, and 15; see Col. 1 Lines 65-67, and Fig. 2 Parts 14 and 15).
Regarding Claim 15, Beals discloses the process according to claim 14.
Beals does not explicitly teach placing coolers in parallel. However, Erchak discloses each of the second or more cooling steps comprising at least two recycle coolers arranged in parallel flow mode (Condensing zones A and B form the preferred parallel arrangement; see Col. 3 Lines 5-8).
Beals and Erchak are both considered to be analogous to the claimed invention because they are in the same field of treatment of polymerization processes. Therefore, it would have been obvious to a person of ordinary skill in the art prior to the effective filing date of the claimed invention to have modified Beals by incorporating the teachings of Erchak and disposing the coolers in parallel. Doing so further ensures that the ethylene stream is substantially completely free of condensable constituents (see e.g. Erchak Col. 3 Lines 29-32).
Regarding Claim 16, Beals and Erchak together disclose the process according to claim 15. Erchak further discloses from one of the at least two recycle coolers the low molecular weight oligomers and wax build-up is removed (passed through a hot cycle in condensing zone A and has removed waxes from said zone; see Col. 3 Lines 13-15) whereas the other of the at least two recycle coolers is in operation mode to cool the recycle gas stream (it is now taken to a cooling cycle with reference to condensing zone B; see e.g. Col. 3 Lines 15-16). This modification would have been obvious to a person of ordinary skill before the effective filing date of the claimed invention because doing so enables condensation of entrained condensable material that was not removed in the hot cycle (see e.g. Col. 3 Lines 13-19).
Regarding Claim 17, Beals and Erchak together disclose the process according to claim 16. Erchak further discloses, after removing low molecular weight oligomers and wax build-up from the one of the at least two recycle coolers, the flow directions are switched (the hot ethylene recycle stream is reversed in flow; see e.g. Col. 3 Lines 44-45) so that said one of the at least two recycle coolers from which the low molecular weight oligomers and wax build-up is removed is switched to operation mode to cool the recycle gas stream, whereas the other from of the at least two recycle coolers is switched from operation mode to the process for reducing low molecular weight oligomers and wax build-up (Condensing zone B after this first phase of treatment of ethylene will accumulate considerable deposits on the surface by virtue of its cooling of the recycle stream. In order to remove these deposits from this unit it must be treated in a hot cycle as described for condensing zone A; see e.g. Col. 3 Lines 39-44). This operation would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention because doing so would aid in removing condensable constituents from ethylene (see e.g. Erchak Col. 3 Lines 19-20).
Regarding Claim 18, Beals discloses the process according to claim 1, being conducted in a continuous high pressure olefin polymerization process (see e.g. Col. 1 Lines 29-31). The remaining limitations of this claim, “wherein in a parallel arrangement of two sets of recycle coolers and wax separators a recycle process is switched from one set to the other set and a dormant set is cleaned”, are claiming the same limitations as claim 17, just using different phrasing. Accordingly, please refer to the rejection of claim 17 for the associated rationale.
Regarding Claim 22, the limitations of this claim do not exceed those of claim 10. Please refer to the rejection of claim 10 for the associated rationale.
Claims 9 and 21 are rejected under 35 U.S.C. 103 as being unpatentable over Beals (US-3627746-A) in view of Erchak (US-3282911-A) and Gas Innovations (Certificate of Conformance, Ethylene Polymer Grade”.
Regarding Claim 9, Beals discloses the process according to claim 1, wherein the gas stream comprises olefin monomers (Ethylene feed; see Col. 1, Line 31). Specifically, Beals teaches the use of ethylene as the gas stream. It would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to use a gas stream to be at least 90 wt% pure olefin monomers because Beals and the instant invention are in the same field of olefin polymerization processes, where the industry standard for polymer grade olefins, including polymer grade ethylene, is above 99.91% (see Gas Innovations).
Regarding Claim 21, Beals discloses the process according to claim 4. The remaining limitations of this claim do not exceed those of claim 9. Please refer to the claim 9 rejection for the associated rationale.
Conclusion
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/A.L.K./Examiner, Art Unit 1774
/CLAIRE X WANG/Supervisory Patent Examiner, Art Unit 1774