Prosecution Insights
Last updated: April 19, 2026
Application No. 18/721,156

PREPARATION METHOD FOR HIGH IMPACT POLYSTYRENE AND HIGH IMPACT POLYSTYRENE

Final Rejection §103§112
Filed
Jun 17, 2024
Examiner
KAUCHER, MARK S
Art Unit
1764
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Changzhou Ruihua Chemical Engineering & Technology Co. Ltd.
OA Round
2 (Final)
72%
Grant Probability
Favorable
3-4
OA Rounds
2y 10m
To Grant
86%
With Interview

Examiner Intelligence

Grants 72% — above average
72%
Career Allow Rate
702 granted / 976 resolved
+6.9% vs TC avg
Moderate +14% lift
Without
With
+14.2%
Interview Lift
resolved cases with interview
Typical timeline
2y 10m
Avg Prosecution
38 currently pending
Career history
1014
Total Applications
across all art units

Statute-Specific Performance

§101
0.5%
-39.5% vs TC avg
§103
41.0%
+1.0% vs TC avg
§102
25.5%
-14.5% vs TC avg
§112
19.8%
-20.2% vs TC avg
Black line = Tech Center average estimate • Based on career data from 976 resolved cases

Office Action

§103 §112
DETAILED ACTION The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior office action. All outstanding objections and rejections made in the previous Office Action, and not repeated below, are hereby withdrawn. The new grounds of rejection set forth below are necessitated by applicant’s amendment filed on 11/13/25. In particular, claims 1 and 10 have been amended to further limit the molecular weight of the low molecular weight vinyl aromatic polymer, and the amounts of the chain transfer agent and the low molecular weight vinyl aromatic polymer. The newly introduced limitations and/or the new claims were not present at the time of the preceding action. For this reason, the present action is properly made final. 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 . Claim Rejections - 35 USC § 112 Claims 1, 3-4, 8-10, 12-13, and 17-19 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention. Claims 1 and 10, which all dependent claims depend upon, have been amended to limit that amounts of chain transfer agent and low molecular weight vinyl aromatic polymer. However, the claim still recites that “a chain transfer agent and/or a low-molecular-weight vinyl aromatic polymer” is add/present. The limitation “and/or” suggests that only one of the components has to be present, however the later ranges suggest that both are present. A broad range or limitation together with a narrow range or limitation that falls within the broad range or limitation (in the same claim) may be considered indefinite if the resulting claim does not clearly set forth the metes and bounds of the patent protection desired. See MPEP § 2173.05(c). In the instant case, it is unclear what is controlling. Do the claims require both a chain transfer agent and a low-molecular-weight vinyl aromatic polymer as implied by the second limitation that limits the amounts of the two components? Do the claims only require a chain transfer agent or a low-molecular-weight vinyl aromatic polymer as implied by the first limitation? In the second interpretation, only one of the ranges need to be met? For these reasons, the two contradictory limitations raise doubts onto what is actually being claimed. For the purpose of the instant action, the claims will be treated as both the ranges are required. Claim Rejections - 35 USC § 103 Claim(s) 1, 4, 8, 10, 13 and 17 is/are rejected under 35 U.S.C. 103 as being unpatentable over RU 2003103721 (herein Potemkim) in view of Florentino Soriano-Corral, et al. "Synthesis and Characterization of High Impact Polystyrene from a Heterogeneous Styrene-Rubber-Polystyrene Solution: Influence of PS Concentration on the Phase Inversion, Morphology and Impact Strength" Macromolecular Symposia, Volume 325-326, Issue 1, 15 April 2013 (2013-04-15), No. 177-183 (herein Corral). In setting forth the instant rejection, a machine translation has been relied upon. As to claims 1, 4, 8, 10, 13 and 17, Potemkim discloses a preparation method for high impact polystyrene(HIPS) and HIPS prepared by the method. See abstract and examples. The method comprises adding chain transfer agent (referred to as regulator MM, which is a translation error of MW (molecular weight) regulator). See page 2 and examples. The chain transfer agent is taught as a dimer of alpha methylstyrene (DAMS). See page 2 and examples. Note that this is the chain transfer agent of claims 4 and 13. The chain transfer agent is added to a mixture of vinyl aromatic monomer (styrene), a solvent, a rubber (polybutadiene rubber/elastomer), a paraffin oil (adjuvant) and an initiator (lauryl peroxide). See examples, such as example 1. The mixture is stirred at 30 to 40 rpm (r/min) in the prepolymerization mode and then polymerized. See examples. Afterwards, the pulp is centrifuged and dried in a dryer (devolatilized) to form HIPS beads. See examples. Example 1 utilizes 0.04 wt%, which correlates to 400 ppm. See example 1 table 1 under “Регулятор ММ-димер альфа-метилстирола, % масс.”. Potemkim is silent on the low molecular weight aromatic polymer. Corral teaches similar methods for producing high impact polystyrene. See abstract and examples. Corral teaches that the addition of about 5 or 7.5 wt% (examples) low molecular weight polystyrene (Mn of about 66,000 g/mol, see examples) improves the impact strength (see conclusion). Note that the purpose of high impact polystyrene is to improve the impact of polystyrene by definition. Further, note that Potemkim generally embraces improving the impact strength (resistance). See examples. Therefore, it would have been obvious at the time of the invention to have modified the method and HIPS of Potemkim with about 5 to 7.5 wt% low molecular weight polystyrene as suggested by Corral because one would want to improve the impact strength. As to the molecular weight note that the Mn (number average molecular weight) is 66,000 g/mol. The weight average molecular weight (Mw, second order) would by definition be the same or slightly larger. Given that Corral requires low molecular weight polystyrene (PS, page 178), it is reasonable to take the position that the Mw would also be within the range of 66,000 g/mol or slightly more and therefore within the claimed range. Claim(s) 1, 3-4, 8-10, 12-13 and 17-19 is/are rejected under 35 U.S.C. 103 as being unpatentable over US 2007/0149686 (herein Casalini) in view of Florentino Soriano-Corral, et al. "Synthesis and Characterization of High Impact Polystyrene from a Heterogeneous Styrene-Rubber-Polystyrene Solution: Influence of PS Concentration on the Phase Inversion, Morphology and Impact Strength" Macromolecular Symposia, Volume 325-326, Issue 1, 15 April 2013 (2013-04-15), No. 177-183 (herein Corral). As to claims 1, 3, 4, 10 and 12-13, Casalini discloses a preparation method for high impact polystyrene(HIPS) and HIPS prepared by the method. See abstract, paragraph 20 and examples. The method involves adding chain transfer agent (TDM, which is t-docecyl mercaptan, see paragraph 40) to a mixture solution. See examples. The mixture solution comprises styrene monomer (vinyl aromatic monomer), antioxidant (adjuvant), rubber (Buna BL 6533 TC, which is a styrene butadiene rubber, also see paragraphs 28-29). The rubber/mixture is dissolved in a solvent (liquid) such as “toluene, ethylbenzene, xylenes or mixtures thereof” (see paragraph 37 and 47). Further, note that the oil also reads on a solvent. See examples. Prepolymerization is performed at 10 to 100 rpm (r/min). See paragraph 48. Afterwards, polymerization is performed. See examples. A drying step (devolatilization) is performed afterwards on the HIPS. See examples. Also see paragraph 41 that outlies the use of vacuum to remove volatiles (e.g. monomers and gas products). Thus, the stirring rate of 10 to 100 rpm (r/min) significantly overlaps the claimed range of 20 to 90 rpm (r/min) as to read on the claimed range. Casalini discloses that the mercaptan is present in 0.005 to 0.5 wt% to monomer (note that in the examples, the monomer is about 5/6 of the mixture), which correlates to about 50 to 5000 ppm, which overlaps the claimed range. It is noted that the examples are just outside at about 800 ppm. Therefore, it would have been obvious to one of ordinary skill in the art at the time the invention was filed to select any amount within the disclosed ranges, including amounts within the scope of the instant claims. Casalini is silent on the low molecular weight aromatic polymer. Corral teaches similar methods for producing high impact polystyrene. See abstract and examples. Corral teaches that the addition of about 5 or 7.5 wt% (examples) low molecular weight polystyrene (Mn of about 66,000 g/mol, see examples) improves the impact strength (see conclusion). Note that the purpose of high impact polystyrene is to improve the impact of polystyrene by definition. Further, note that Casalini generally embraces improving the impact strength (resistance). See paragraph 21 and examples. Therefore, it would have been obvious at the time of the invention to have modified the method and HIPS of Casalini with about 5 to 7.5 wt% low molecular weight polystyrene as suggested by Corral because one would want to improve the impact strength. As to the molecular weight note that the Mn (number average molecular weight) is 66,000 g/mol. The weight average molecular weight (Mw, second order) would by definition be the same or slightly larger. Given that Corral requires low molecular weight polystyrene (PS, page 178), it is reasonable to take the position that the Mw would also be within the range of 66,000 g/mol or slightly more and therefore within the claimed range. As to claims 8 and 17, the polymerization is performed in the presence of an initiator (peroxide). See examples and paragraph 48-50. As to claims 9 and 18, the Prepolymerization is performed at 120 oC and the polymerization is performed at 150 oC. See examples. Also see paragraph 48 stating that the Prepolymerization is between 70 and 150 oC and paragraph 50 stating that the polymerization is between 100 and 170 oC. As to the molecular weight, note that the Mn (number average molecular weight) is 66,000 g/mol. The weight average molecular weight (Mw, second order) would by definition be the same or slightly larger. Given that Corral requires low molecular weight polystyrene (PS, page 178), it is reasonable to take the position that the Mw would also be within the range of 66,000 g/mol or slightly more and therefore within the claimed range. As to claim 19, see figure 19, wherein the HIPS has a honeycomb structure. Specifically see below. PNG media_image1.png 200 219 media_image1.png Greyscale Response to Arguments Applicant's arguments have been fully considered but they are not persuasive. Applicant argues that “it is surprisingly found that the morphological structure of the prepared HIPS is maintained and the impact strength is improved within a certain shearing rate range.” In response, this is not found persuasive. No examples has both the low molecular weight vinyl aromatic polymer and the chain transfer agent. The examples only have one component, which both Potemkim and Casalini read on. Applicant argues that Potemkim (or Casalini) adds chain transfer agent for a different reason. In response, this is not persuasive. The reason for adding is moot if the product/process is the same. 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. Any inquiry concerning this communication or earlier communications from the examiner should be directed to MARK S KAUCHER whose telephone number is (571)270-7340. The examiner can normally be reached M-F 8-6 PM EST. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Arrie Lanee Reuther can be reached at (571) 270-7026. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /MARK S KAUCHER/Primary Examiner, Art Unit 1764
Read full office action

Prosecution Timeline

Jun 17, 2024
Application Filed
Aug 12, 2025
Non-Final Rejection — §103, §112
Nov 13, 2025
Response Filed
Dec 01, 2025
Final Rejection — §103, §112 (current)

Precedent Cases

Applications granted by this same examiner with similar technology

Patent 12600851
THERMOPLASTIC COMPOUNDS CONTAINING RECYCLING MATERIAL WITH SUPERIOR QUALITY
2y 5m to grant Granted Apr 14, 2026
Patent 12600844
Linear Low Density Polyethylene for Film Applications
2y 5m to grant Granted Apr 14, 2026
Patent 12600846
POLYMERIC SUBSTRATE INCLUDING A BARRIER LAYER
2y 5m to grant Granted Apr 14, 2026
Patent 12595321
CATALYST SYSTEM BASED ON A RARE-EARTH METALLOCENE AND A CO-CATALYST HAVING A PLURALITY OF CARBON-MAGNESIUM BONDS
2y 5m to grant Granted Apr 07, 2026
Patent 12595331
SYNTHESIS OF BLOCK POLYMERS BASED ON 1,3-DIENE AND ETHYLENE
2y 5m to grant Granted Apr 07, 2026
Study what changed to get past this examiner. Based on 5 most recent grants.

AI Strategy Recommendation

Get an AI-powered prosecution strategy using examiner precedents, rejection analysis, and claim mapping.
Powered by AI — typically takes 5-10 seconds

Prosecution Projections

3-4
Expected OA Rounds
72%
Grant Probability
86%
With Interview (+14.2%)
2y 10m
Median Time to Grant
Moderate
PTA Risk
Based on 976 resolved cases by this examiner. Grant probability derived from career allow rate.

Sign in with your work email

Enter your email to receive a magic link. No password needed.

Personal email addresses (Gmail, Yahoo, etc.) are not accepted.

Free tier: 3 strategy analyses per month