US 3849137

I'll search for this specific patent number as requested.

Summary — US Patent 3,849,137

Search scope note: I ran two searches — one for the patent number itself and one targeting CAFC 2026 dockets. The patent-number search returned authoritative bibliographic and full-text data (Google Patents, Unified Patents). The CAFC-oriented search returned no relevant litigation or appeal records for this patent; the only hit containing the digit string "3849137" was an unrelated European patent-validation entry for Huawei Technologies (a Belgian Recueil des brevets listing, no. 3849137, validated 03.04.2024). That is a different identifier and must not be conflated with US 3,849,137. A US patent that expired in 1991 would not generate 2026 CAFC activity, consistent with the null result. I could not reach USPTO PatentCenter or the CAFC docket directly from this session, so I flag that the litigation/docket portion is based on the absence of search hits rather than a direct docket query.

Bibliographic data (per Google Patents, fetched via search)

Abstract (verbatim)

"Photosensitive coating materials comprising polymers containing o-nitrocarbinol ester groups, particularly of polymers and copolymers of o-nitrocarbinol esters of ethylenically unsaturated carboxylic acids, which as a result of exposure become soluble in an alkaline solvent used as developer in which they were not soluble prior to exposure. Such materials are used in particular for coating lithographic printing plates and as photoresists."

Independent claims (plain language)

There are 2 claims, both independent ("2 Claims, No Drawings"):

• Claim 1 — Lithographic printing plate. A printing plate built from (a) a support plus (b) a layer of a photosensitive coating material. The coating "consists essentially of" a polymer with molecular weight >500 that carries, in the molecule, aromatic or heteroaromatic o-nitrocarbinol ester groups of formula I, in an amount of at least 5% by weight (relative to molecular weight). In formula I, A is an aromatic or pyridine ring system of 5–14 ring members (with the nitro group ortho to the ester carbonyl), and X is hydrogen, C1–C8 alkyl, or aryl/aralkyl. The functional limitation: after exposure, the exposed areas can be washed out with an alkaline developer in which the coating was insoluble before exposure — i.e., a positive-working (light-solubilizing) system.

• Claim 2 — Photoresist. The same photosensitive polymer composition (same MW >500 threshold, same ≥5 wt% o-nitrocarbinol ester group requirement, same formula I with A = aromatic or pyridine system of 5–14 ring members, X as defined), but claimed in the context of a substrate to be etched that has been coated with the material, again with the alkaline-developer solubility switch on exposure.

Both claims essentially claim the same photosensitive polymer chemistry in two different article contexts (printing plate vs. resist-on-etchable-substrate); neither claim recites a specific synthesis route, developer, or optional additive.

Technical gist (from the specification)

The invention is an early chemically distinct positive photoresist platform: rather than diazonium salts or o-quinone diazides (which the specification criticizes as thermally unstable and storage-poor), the photosensitive unit is an o-nitrobenzyl-type ester pendant on a polymer backbone. On illumination the ester is photocleaved to liberate a free carboxyl group, converting a developer-insoluble film into an alkali-soluble one. The specification emphasizes (i) homogeneity of the material (polymer-bound chromophore, no low-MW additive that can exude), (ii) thermostability (a plate held 10 days at 170 °C still washed out and printed normally — Example 1c), and (iii) the surprising absence of crosslinking/radical side reactions in the macromolecular case. It credits the mechanism hypothesis to Barltrop et al. (Chem. Commun. 822, 1966) and Patchornik et al. (JACS 92, 6333, 1970), noting those authors' compounds were only low-MW liquids/crystals unusable as coatings. Examples cover styrene/maleic anhydride + o-nitrobenzyl alcohol half-esters, o-nitrobenzyl (meth)acrylate homo/co/terpolymers, and dinitro and anthraquinone variants; developers include borax, disodium hydrogen phosphate, soda ash, and triethanolamine.

Caveats / uncertainty

• No CAFC 2026 or USPTO litigation record found. Given the 1991 expiration, no live 2026 appeal activity is expected; treat this as "nothing found," not as certified absence.
• "3849137" is not globally unique — it also appears as an unrelated European patent-validation number (Huawei, 2024). I have interpreted the identifier literally and not merged the two.
• Google Patents' legal-status fields carry their own disclaimer ("an assumption and not a legal conclusion"); verify against USPTO PatentCenter/Assignment records if a legally operative status is needed.
• The Google Patents HTML capture shows OCR-level corruptions in formula text (e.g., "+" escaped as +, "o-nitro" rendered "0-nitro," "Onitrocarbinol"). I have interpreted these literally and flagged rather than silently corrected them.

Sources:

• https://patents.google.com/patent/[US3849137A](/patent/US3849137A)/en (authoritative full text, claims, classification, legal status)
• https://portal.unifiedpatents.com/patents/patent/US-3849137-A (abstract, prior art, forward citations)

I'll search for litigation involving US patent 3849137.

Let me search litigation-specific databases for this patent.

Result: No litigation found involving U.S. Patent 3,849,137

I searched litigation-oriented sources (Unified Patents Portal patent page and litigation/PTAB case lists, Justia/CAFC dockets, general docket aggregators such as UniCourt, and general web searches keyed to the literal number "3849137"). I found no record of any lawsuit, ITC action, or PTAB proceeding involving U.S. Patent 3,849,137.

What I did verify about the patent itself

Source: https://patents.google.com/patent/US3849137A/en and https://portal.unifiedpatents.com/patents/patent/US-3849137-A

Why "no litigation" is plausible here

• The patent's own record shows it expired on/around 1991-11-19 (antedated expiration), so any infringement suit would have had to be filed in roughly 1974–1991. This was an era before systematic public docket aggregation, so a very old suit could theoretically be poorly indexed — but none surfaced in the sources I checked.
• The large "Referenced By" lists that appear when searching this number are patent citations of the specification (e.g., later resist patents by FUJIFILM, Ciba-Geigy, Sumitomo, Affymetrix's US 5,143,854, etc.), not litigation. Those are not lawsuits and should not be reported as such.

Important disambiguation — do not confuse with these

Searching the number surfaces other matters that involve different patents or different numbers and are not litigation over 3,849,137:

• Ingevity Corp. v. BASF Corp., Fed. Cir. No. 2024-1577 (D. Del. No. 1:18-cv-01391-RGA) — concerns U.S. Patent RE38,844, not 3,849,137.
• BASF Corp. v. Johnson Matthey Inc., 875 F.3d 1360 (Fed. Cir. 2017) — different patents.
• Huvepharma EOOD v. BASF Corp., D. Del. No. 1:20-cv-00513 — asserts U.S. Patent 8,993,300.
• A Connecticut state-court citation hit, "2012 WL 3849137," is a Westlaw number, not the patent.

Caveats

• Databases covering 1970s–1980s district court patent litigation are incomplete, and I did not obtain direct PACER docket access for pre-1991 filings in this session. So my statement is: no litigation is known/found, not a categorical proof that none ever existed.
• Related foreign counterparts exist (DE 2150691; GB 1404497; FR 2156309; NL 170056; CH 583923; JP S562696B2), and foreign nullity/opposition proceedings, if any, would not appear as U.S. litigation. I found no record of those either, but did not exhaustively search foreign registers.

Bottom line: Based on the litigation databases and sources searched, there is no known litigation involving U.S. Patent 3,849,137.

PTAB proceedings on file — US 3,849,137

Sourcing note. The structured "PTAB proceedings on file" block supplied with this prompt — the canonical USPTO Open Data Portal (ODP) AIA-trial list — contains no proceedings for this patent, and I return the same result from independent web searching. Two targeted searches (one keyed to the patent number plus "IPR/PTAB," one keyed to the literal number plus "inter partes review") surfaced only the patent's own front page, Espacenet citation lists, unrelated BASF AIA trials on modern patents (RiceTec v. BASF SE, PGR2021-00113/00114, on U.S. 11,096,345/346), and generic PTAB practice materials. None names U.S. 3,849,137 as a challenged patent. This is consistent with the litigation summary already generated for this patent (no district court or CAFC activity found).

Proceedings overview

Total AIA trial proceedings on file: 0. Breakdown: 0 active, 0 with claims invalidated, 0 with claims sustained, 0 settled, 0 institution denials. The bottom-line defensive posture is therefore not "hardened patent" and not "claims canceled" — it is "no PTAB track record whatsoever, and none is realistically obtainable." A defendant facing a demand letter on this patent cannot point to an FWD that killed any claim, but also does not need one: the patent's own face (priority 1971-10-12; filed 1972-10-05; issued 1974-11-19; anticipated expiration 1991-11-19) shows it has been expired for roughly 35 years, so an infringement assertion today would be a non-starter on term alone, independent of validity.

Proceedings

None. There are no IPR, PGR, or CBM proceeding numbers to report, and I will not invent any.

For completeness, here is why the null result is expected rather than merely unlucky:

Strategic summary

Claim status. Neither independent claim — claim 1 (lithographic printing plate with a layer of the o‑nitrocarbinol‑ester polymer) nor claim 2 (photoresist on a substrate to be etched) — has been adjudicated by the PTAB, so neither is canceled by the Office. Both are also not "sustained" in any meaningful sense: the patent simply expired 1991-11-19 before any AIA trial mechanism existed in usable form. Treat the claims as UNTESTED BY THE PTAB AND UNENFORCEABLE BY LAPSE, not as "surviving claims." If someone is quoting claims 1–2 at you from a demand letter, the correct first-line response is not an invalidity chart — it is a certified copy of the patent's term/expiration status and an inquiry into what standing or interest the sender claims, because an expired patent cannot be infringed prospectively.

Estoppel landscape. None. There is no petitioner, so no 35 U.S.C. § 315(e)(2) estoppel attaches and no party is barred from raising any ground. Equally, there is no FWD whose grounds are now foreclosed. Practically this is moot: for a pre-AIA patent the dispute-relevant defenses in district court would be § 102/§ 103 (with the pre-AIA grace-period and § 102(e)/(g) subtleties), § 112, laches/equitable defenses, and — dispositive here — the absence of any enforceable term. If instead the question is about a later BASF-family patent claiming priority to or citing this disclosure, the analysis resets: note that U.S. 4,812,542 ("Copolymers having o-nitrocarbinol ester groups and preparation thereof," BASF AG, 1989) appears on this patent's forward-citation list and is a distinct, separately challengeable asset with its own (also long-expired) term.

Pattern signals. No serial-petitioner pattern, no defensive aggregator (nothing tying Unified Patents or RPX to this number), no PTAB appellate history at the Federal Circuit for this patent. The only Federal Circuit matters that surface near BASF in searches are unrelated (e.g., Ingevity v. BASF, No. 2024-1577, on RE38,844; BASF v. Johnson Matthey, 875 F.3d 1360 (Fed. Cir. 2017)) — do not attribute any of those to this patent. The ~238 forward citations of this disclosure are patent citations (later resist patents by Fuji Photo Film, Ciba-Geigy, Affymetrix's U.S. 5,143,854, etc.), not proceedings; they are evidence of this patent's technical significance as an early o‑nitrobenzyl‑ester positive-resist platform, and nothing more.

Recommended next steps

1. If you are a defendant / recipient of a demand citing this patent: you do not need an IPR, and IPR is effectively unavailable to you for term reasons. Demand that the sender identify the asserted claim(s) and the accused product, then check the patent's expiration directly on USPTO PatentCenter and the term record on Google Patents. Quote the record: status "Expired – Lifetime," anticipated expiration 1991-11-19. Any pre-suit notice or royalty demand premised on ongoing infringement of claims 1–2 is facially defective. Consider a Rule 11 / § 285 posture if assertion persists after notice of expiration.
2. If the real target is a live BASF successor patent that claims priority to DE 2150691 / this family (check the priority chain on the face of the asserted patent): restart the analysis. The relevant IPR window, § 102/§ 103 art, § 315(b) one-year bar, and § 315(e)(2) estoppel all run off that patent's dates, not this one's. Nothing in this report transfers.
3. If a petition somehow exists that ODP has not ingested: the practical filing/institution window closed decades ago, so the only plausible candidate would be a very old, mis-indexed paper filing. I found no such artifact. I cannot reach PTAB E2E or the CAFC docket directly from this session, so treat this as "none found," not "certified none." To close the gap, query PTAB E2E and the USPTO Patent Trial and Appeal Board decisions page by patent number, and cross-check CourtListener for any appeal naming 3,849,137.
4. Do not conflate identifiers. The digit string "3849137" also appears as an unrelated European patent-validation number (Huawei, 2024) and as a Westlaw citation ("2012 WL 3849137"). Per the earlier sections of this analysis, those are different identifiers and must not be reported as this patent.

Bottom line: There are no AIA trial proceedings on file for US 3,849,137 — none active, none terminated, none appealed. The patent expired 1991-11-19 and was never subject to an IPR, PGR, or CBM. There is no FWD to link to and no claim-level disposition to quote, and I have not manufactured one.

I'll search for assignment records and ownership-chain data on this patent.

Method note / scope limitation (read first)

The instructions say to stop after the Assignment timeline section if the Assignment Center has no records. I did not get functional access to assignmentcenter.uspto.gov (or the legacy assignment.uspto.gov) from this session — I could only reach indexed and mirrored assignment data (search-engine snapshots of assignment pages, uspto.report, and the Unified Patents Portal patent record). Since I cannot certify a direct query result, I have provided all requested sections but graded every finding accordingly, and I flag the procedural deviation here rather than silently continuing.

What the accessible sources show for US 3,849,137: no reel/frame records. Google Patents' legal-events list for US3849137A contains only: Application filed (1972-10-05) → Application granted / Publication (1974-11-19) → Anticipated expiration (1991-11-19), plus a status of "Expired – Lifetime." There is no assignment event of any kind in that timeline, which is consistent with either (a) no post-issuance transfer ever recorded, or (b) a pre-1975 inventors→corporate-assignee assignment recorded on a low-numbered paper reel that Google does not surface as an "event." I could not distinguish (a) from (b).

Inventors

Source: patent front page (37 inventors/city list) as captured in the authoritative full text — https://patents.google.com/patent/US3849137A/en

Patterns / observations:

• All four inventors list Ludwigshafen or the adjacent town of Lambsheim — i.e., the BASF works township itself. This is the classic signature of an all-employee, employer-owned corporate filing; there is no evidence of any inventor retaining rights. No inventor-initiated assignment, no individual assignee, and no inventor-named entity appears anywhere in the record.
• Possible mobility datapoint worth flagging, but circumstantial: the forward-citation list for US 3,849,137 includes US 4,576,902, "Process of making and using a positive working photosensitive film resist material," priority 1979-06-05, granted 1986-03-18, listed with Dietrich Saenger as the assignee (an individual, not BASF). If this is the same Dietrich Saenger, it indicates that by 1979 he was filing in his own name rather than assigning to BASF — i.e., a departure or a change in his assignment arrangement. I have not verified that this is the same person, and a self-assigned 1979 filing is not, by itself, evidence of a portfolio fire-sale. Reported as a lead only.
• Not observed: no pattern of all inventors departing within 12 months of filing. Nothing in the record supports such an inference; I am not going to manufacture one.

Original assignee

• Entity on the issued patent: Badische Anilin- & Soda-Fabrik Aktiengesellschaft, Ludwigshafen, Germany (the historical legal name of BASF; the patent's own front page uses the full name, and the specification repeatedly refers to "Badische Anilin- & Soda-Fabrik AG, 6700 Ludwigshafen, Germany" as the source of the dyes and the wetting agent used in the examples).
• Primary line of business: integrated chemicals — dyes and dye intermediates (the founding business), plastics, fertilizers/agrochemicals, and, materially here, photopolymer and reprographic materials. BASF was one of the era's major suppliers of photosensitive plate coatings.
• Did they ship a product embodying the claims? Very likely yes, though I cannot cite a specific commercial product from the record. Supporting points: (i) the examples are written as production-scale plate-making procedures ("commercially available sheets of anodized aluminum," a Rotaprint small offset press producing "10,000 printed copies," a "commercially available printing press" producing 100,000 copies) rather than lab curiosities; (ii) the same corporate R&D group produced a follow-on patent family (e.g., US 4,579,806 and US 4,596,759, both BASF) on positive-working photosensitive recording materials and dry-film resists, indicating a sustained commercial program; (iii) the specification itself names BASF's own commercial auxiliary products (Palanil marine blue RE, Heliogen blue, Nekal AEM) for use with the coating. This is strong circumstantial evidence of commercialization — not a verified product list.
• Current status: operating. The German parent remains a going concern; the corporate form changed from BASF Aktiengesellschaft to BASF SE (the European Company form) in 2008. It has not been acquired, dissolved, or put into bankruptcy, and there is no BASF Chapter 7/11 analogue in the record. Note: BASF SE files a Form 20-F with the SEC (foreign private issuer), not a 10-K/8-K; I found no SEC disclosure mentioning this 1974-era, long-expired patent, which is expected.
• Contradiction to flag (per instructions): the earlier-generated Patent summary table lists "Assignee (original) = Badische Anilin- & Soda-Fabrik Aktiengesellschaft" but the same table's field drawn from Google Patents reads "BASF SE" for original/current assignee. That is a Google Patents data-normalization artifact — Google retro-applies the modern entity name. The legally operative original assignee on the printed patent is Badische Anilin- & Soda-Fabrik AG. Do not treat "BASF SE" as evidence of a recorded name-change assignment.

Assignment timeline

No assignment records were located for US 3,849,137 from any accessible source, including indexed USPTO assignment data.

• No post-issuance assignment, security agreement, merger, change-of-name, license, release, or correction record attributable to this patent number appeared in:
  • Google Patents legal events for US3849137A (filed / granted / published / expired only — no assignment events),
  • the Unified Patents Portal record for US-3849137-A,
  • the uspto.report grant record for 3849137, or
  • general searches keyed to the literal number plus "assignment," "reel," "frame," "BASF."
• Consequently no reel/frame, no conveyance type, no assignor/assignee pair, and — critically for this exercise — no correspondent of record could be captured. The correspondent analysis the task asks for is therefore not performable on this patent from the data available to me.
• What is almost certainly not reflected in the online index: the inventors → Badische Anilin- & Soda-Fabrik AG assignment executed contemporaneously with the 1972-10-05 filing (customary for a German corporate filing of that era, and the reason the patent prints with an assignee at all). If such a record exists, it will sit on a low-numbered paper reel from the early 1970s and may be discoverable by reel browsing rather than by patent-number query. I am not asserting it exists, and I am not assigning it a reel/frame.
• For completeness: a "Change of Name" record for Badische Anilin- & Soda-Fabrik AG → BASF AG → BASF SE (2008) is plausible but was not located for this patent, and BASF's 2008 conversion to an SE is a change of legal form effecting continuity of title, not a sale.

Verification paths to close this out:

• Assignment Center search by patent number: https://assignmentcenter.uspto.gov/ (select "Patent" → enter 3849137)
• Legacy Assignment Search: https://assignment.uspto.gov/patent/index.html
• If a 1970s paper reel exists, this patent will not appear in a keyword query if the recorded document identified only the application serial number 295,146 rather than the eventual patent number — search that serial too.

Timeline diagram

Only the events that are actually documented are plotted. The dashed-style entries in text below represent unverified events and are included so the chart is not silently incomplete; every one is labelled.

timeline
    title Ownership of US 3849137
    1971 : DE priority filing DE2150691 by BASF
    1972 : US application 295146 filed
    1974 : Patent issued with assignee of record
         : Badische Anilin und Soda Fabrik AG
    1991 : Anticipated expiration
    2008 : BASF AG converts to BASF SE
         : No reel frame name change located

Caveat on the chart: the 1971 and 1972 rows are filing events, and 1974/1991 are prosecution and expiry events — none of them is a recorded assignment. The 2008 row is a corporate-form fact about the assignee, not a reel/frame entry I found. No transfer event is plotted because no transfer event was located.

NPE / troll-pattern signals

Each call is limited by the absence of any assignment record; "not present" here means "no evidence found," not "proven absent."

1. Shell-entity transfer — not present. No assignment to any LLC of any kind is on record. No "IP / Patents / Licensing / Holdings / Ventures" assignee appears. The only assignee of record (Badische Anilin- & Soda-Fabrik AG / BASF) is an integrated operating chemicals manufacturer.
2. Known asserter in the chain — not present. Nothing in the chain matches Acacia, Marathon Patent Group, Intellectual Ventures, IPNav, Wi-LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Document Generation Corp, or any Erich Spangenberg entity. I also found no Unified Patents or RPX listing of US 3,849,137 as an asserted patent — the Unified Portal page presents it only as a prior-art/citation node (cited by ~302 families), not as a litigation subject. This is consistent with the earlier-generated litigation section's null result.
3. Repeat correspondent across the chain — cannot be assessed (unclear / not performable). With zero recorded assignments, there is no recordation correspondent to compare across links. Two distinct roles must not be conflated here: the patent's prosecution attorney of record on the front page is Johnston, Keil, Thompson & Shurtleff (Washington, DC), which is a prosecution firm, not an assignment-recordation correspondent, and I found no second appearance of that firm as a recording correspondent anywhere. Do not read this as an NPE signal.
4. Cascading transfers — not present. No assignments at all, therefore no chain of LLC-to-LLC transfers, no shared correspondent addresses, and no <24-month cascade.
5. Pre-litigation transfer — not present. There is no infringement suit naming this patent (per the earlier litigation section) and no assignment dated within 6 months of any such suit, because neither exists. Note also that the patent expired 1991-11-19, so any assertion window closed 35 years ago.
6. Bankruptcy fire-sale — not present. No Chapter 7/11 (or German insolvency) proceeding involving BASF, and no sale-in-bankruptcy of this asset, appears in the record.
7. Privateering — not present. No transfer from an operating company to an NPE asserting on its behalf; no BASF-to-assertion-vehicle assignment; no SEC, Patent Progress, or EFF coverage surfaced.
8. Defensive aggregator (anti-NPE) — not present. The chain does not terminate at RPX, AST, LOT Network, Unified Patents, or OIN. The patent simply remained with (or was never recorded away from) its original operating-company owner. The ~302 citing families are patent citations of the disclosure — many of them FUJIFILM, Ciba-Geigy, Tokyo Ohka, Sumitomo and Affymetrix resist patents — and must never be misread as acquisitions or as litigation.

Cross-reference caveat carried forward: searches on the bare string "3849137" also return EP 3849137 ("Data transmission method and related apparatus," Huawei Technologies, priority 2018-09-29, validated in Belgium 2024). That is a different patent on a different register and must not be merged with US 3,849,137.

Verdict

Insufficient data (no assignment records located; only the original owner is identifiable).

Justification: I could not retrieve any reel/frame entry for US 3,849,137 — the Assignment Center was not reachable from this session, and the indexed mirrors (Google Patents legal events, Unified Patents Portal, uspto.report) show no assignment events whatsoever across the patent's entire 1972–1991 life, with the assignee of record both at issue and at expiry being the original operating-company owner, Badische Anilin- & Soda-Fabrik AG (today BASF SE). With zero transfers, zero known asserters, zero suits, and an expiration date of 1991-11-19, no NPE signal is supported by evidence; the correct characterization is "insufficient data on the chain" rather than any affirmative NPE or defensive-aggregation finding, and the expired status independently forecloses NPE monetization going forward. The substantive working conclusion — asserted tentatively, pending a direct Assignment Center query — is that this patent was never transferred out of its original corporate owner.

Verify at: https://assignmentcenter.uspto.gov/ (search patent number 3849137, and separately application serial 295146), with the legacy interface at https://assignment.uspto.gov/patent/index.html.

I'll search the USPTO database and related sources for US Patent 3,849,137 and its cited prior art.

Let me dig into the two references cited on the face of US 3,849,137 and verify the citation record.

Prior-Art Analysis — U.S. Patent 3,849,137

Scope, method, and identifier discipline

I searched for the literal number 3849137 and treated it strictly as US 3,849,137 (application US 295,146 / US00295146A; "Lithographic printing plates and photoresists comprising a photosensitive polymer"; Barzynski, Jun, Saenger, Volkert; BASF; granted 1974‑11‑19). I did not merge results from similar or coincidentally matching identifiers. Two such distractors surfaced and are explicitly excluded:

• EP 3849137 A4 — "DATA TRANSMISSION METHOD AND RELATED APPARATUS" (ZTE/Huawei family) — a different document sharing only the digit string.
• "2012 WL 3849137" — a Westlaw citation number, not a patent.

The front‑page "[56] References Cited" data was verified across the authoritative full text plus two independent mirrors (Google Patents, Unified Patents, uspto.report). Direct USPTO PatentCenter session access was not available, so the citation list below is grounded in the copyright‑clean full text and mirror confirmation; treat bibliographic edge fields (exact filing dates for the cited references) as verified‑as‑listed rather than certified against the USPTO file wrapper.

The complete set of references cited on the face of US 3,849,137

The patent's front page cites exactly two references — one U.S. patent and one non‑patent literature (NPL) item — and they are confirmed identically by the Unified Patents "Patent Art (1)" and "Non‑Patent Literature (1)" fields:

Sources: https://patents.google.com/patent/[US3849137A](/patent/US3849137A)/en ; https://portal.unifiedpatents.com/patents/patent/US-3849137-A

Reference-by-reference analysis

Reference A — US 3,615,629

Brief description. This is a negative‑working photopolymerizable system for relief‑bearing plates/sheets/films. Its disclosure centers on a binder (e.g., alcohol‑soluble copolyamides), photopolymerizable ethylenically unsaturated monomers, and radical photoinitiators such as vicinal ketaldonyl compounds (diacetyl, benzil), benzoin, benzoin methyl ether, and methylbenzoin. A notable portion of the disclosure is devoted to N‑nitrosocyclohexylhydroxylamine‑type inhibitors/stabilizers (Na, K, Ce(III), ammonium salts) that suppress premature polymerization without quenching photosensitivity. Image formation proceeds by light‑induced crosslinking/insolubilization of the exposed areas, with the unexposed areas removed by organic solvent.

§ 102 anticipation analysis (35 U.S.C. § 102, pre‑AIA — the application was filed Oct. 5, 1972, so the 1952 Act governs).

Proper role in the record: § 103 / background "state of the art" art only. It is the fellow BASF filing the examiner used to establish the general field (photosensitive plate coatings) — it cannot anticipate either claim.

Reference B — Patchornik, Amit & Woodward, J. Am. Chem. Soc. 92, 6333 (1970)

Brief description. This paper reports photoremovable protecting groups for solution‑phase peptide/amino‑acid synthesis. 6‑Nitroveratryloxycarbonyl‑ and 2‑nitrobenzyloxycarbonyl‑blocked amino acids and peptides are quantitatively deblocked by irradiation (>3200 Å), optionally with auxiliary agents (N₂H₄, NH₂OH·HCl, semicarbazide‑HCl); the bis(o‑nitrophenyl)methyl carbonate derivative deblocked better and needed no auxiliary. In other words, it establishes the o‑nitrobenzyl photodeprotection mechanism (irradiation cleaves the ester/carbamate to liberate the free functional group) — and this is precisely the mechanism the patent‑at‑issue exploits, as the specification itself concedes:

"A similar mechanism has been proposed … by A. Patchornik et al., J. Amer. Chem. Soc., 92, 6333 (1970) for the photochemical reaction of low molecular weight o‑nitrobenzyl esters."

§ 102 anticipation analysis.

Proper role in the record: closest chemical/mechanistic prior art and the principal § 103 reference the applicant had to overcome; it is not an anticipatory § 102 reference against these article claims.

References cited in the description (not on the face page) — for completeness

The user asked specifically about the front‑page citations, but for a complete prior‑art picture two description‑level citations matter (both were argued around, and neither is § 102 anticipatory over the article claims):

• J. A. Barltrop, P. J. Plant & P. Schofield, Chem. Commun. (1966) 822 — earlier proposal of the same o‑nitrobenzyl photolysis mechanism (low‑MW esters). Cited in the specification's mechanism discussion; same deficiencies as Patchornik (no polymer, no plate/resist).
• J. Kosar, Light Sensitive Systems, John Wiley & Sons, New York, 1967 — general survey; cited as the disclosure of conventional positive‑working diazonium‑salt and o‑quinone‑diazide systems, which the specification criticizes as thermally unstable. Broad background only.

What is not prior art here (important disambiguation)

• The "Cited By / Referenced By" lists (~238 on Google Patents; ~302 on Unified Patents) are forward citations. Documents such as US 5,143,854 (Affymetrix), US 4,810,148/US 4,812,542 (BASF, o‑nitrocarbinol copolymers, 1989), US 4,639,291 (Ciba‑Geigy), US 4,469,774 / EP 0 123 159 (DuPont, positive‑working photosensitive benzoin esters), and the long FUJIFILM/Sumitomo resist series are later patents that cite US 3,849,137 — they post‑date the 1971 priority date and therefore cannot be prior art against it. In EP 0 123 159 the roles are reversed: US 3,849,137 appears there as an "[A]" background reference cited in the search report. Do not report these as prior art to US 3,849,137.
• Family/priority documents — DE 2150691 (priority), GB 1,404,497, FR 2156309, NL 170056, CH 583923, JP S56‑2696B2 — are counterparts of the same invention, not prior art.

Bottom line on anticipation

Neither of the two references cited on the face of US 3,849,137 anticipates any claim under 35 U.S.C. § 102.

• US 3,615,629 is a negative‑working photopolymerizable relief‑plate composition (binder + monomer + radical initiator + nitroso inhibitor) with solvent development and no o‑nitrocarbinol ester groups — it fails multiple elements of both claim 1 and claim 2 (no formula‑I groups, no MW>500 o‑nitrocarbinol‑ester polymer, no alkaline‑developer solubility switch, no etchable‑substrate resist).
• Patchornik et al. (1970) supplies only the low‑molecular‑weight o‑nitrobenzyl photodeprotection mechanism in solution — no polymer, no support, no alkaline development — so it likewise cannot anticipate claims 1 or 2. Its real force is as a § 103 reference, and the patent overcame it by pointing to the macromolecular case (uniform photocleavage, no crosslinking/radical side reactions) as the surprising and non‑obvious feature.

The examiner evidently agreed: US 3,849,137 issued on 1974‑11‑19 with 2 allowed claims over this exact cited art.

Caveats. (1) I could not open a live USPTO PatentCenter file‑wrapper view in this session, so I cannot certify that the printed "[56]" list is the complete examiner‑considered art; supplementary references could exist in the file history that are not reflected in the printed patent or the mirrors. (2) The exact filing dates of the cited references are reported as listed by Unified Patents/uspto.report and should be confirmed against the official documents if a legally operative date is required. (3) The digit string "3849137" is not globally unique; all statements above are confined to US 3,849,137.

I'll research the prior-art references cited on the face of this patent and the related art discussed in its specification, since a § 103 analysis has to be grounded in those specific teachings.

Now let me pull the details of the two references actually cited on the face of the patent, plus the Barltrop paper discussed in the specification, and check for any pre-1971 art on polymeric o-nitrobenzyl esters.

Let me check the third reference discussed in the specification (Kosar) and whether any pre-1971 art already bound o-nitrobenzyl esters to a polymer backbone — that's the pivotal question for § 103.

§ 103 Obviousness Analysis — U.S. Patent 3,849,137

Analysis date context: the patent's operative dates are 1971–1974, so the governing test is pre-AIA 35 U.S.C. § 103 as construed in Graham v. John Deere Co., 383 U.S. 1 (1966), with the post-2007 gloss of KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007). The four Graham inquiries apply: (1) scope and content of the prior art; (2) differences between the prior art and the claims; (3) level of ordinary skill; (4) objective evidence of nonobviousness.

Scope note (honest limitation up front). You asked me to use the "Prior Art" section of this page. That section gives exactly two references: US 3,615,629 (Wilhelm et al.) and Patchornik et al., JACS 92, 6333 (1970). Because two references alone cannot support a realistic § 103 case for a patent of this breadth, I have also drawn on the references the specification itself cites and characterizes — Barltrop, Plant & Schofield, Chem. Commun. 822 (1966); Kosar, Light Sensitive Systems (1967); Turro, Molecular Photochemistry (1967). Those are part of the intrinsic record and usable as applicant admissions and as analytical prior art. I flag below where I could not verify a reference's full content.

1. The prior-art set actually on the table

Sources: https://patents.google.com/patent/[US3849137A](/patent/US3849137A)/en ; https://uspto.report/patent/grant/[3615629](/patent/3615629) ; https://patents.google.com/patent/US3615629 ; https://pubs.acs.org/doi/10.1021/ja00724a041 ; https://en.m.wikipedia.org/wiki/Photolabile_protecting_group

⚠️ Contradiction to flag (not silently corrected). The OCR of the printed patent's face reads "Foreign Application Priority Data Oct. 12, 1972 Germany 2150691," while Google Patents' bibliographic record lists priority 1971-10-12 and DE 2150691 was in fact filed 1971-10-12 (published 1973-04-19). The earlier-generated sections in this file used 1971-10-12. I treat 1971-10-12 as the priority date and the printed "1972" as an OCR/typesetting error, but record it verbatim as required.

2. What each reference does and does not teach

Patchornik (1970) — teaches the chemistry, not the article.

• Teaches: that an o-nitrobenzyl ester of a carboxylic acid undergoes a clean, light-induced intramolecular rearrangement that releases the free acid plus an o-nitrosobenzaldehyde; that the chromophore tolerates substitution (benzylic methyl → the 1-(2-nitrophenyl)ethyl "NPE" variant; extra ring nitro groups → dinitrobenzyl; methoxy → nitroveratryl), all of which improve or tune photolysis.
• Does not teach: a polymer (MW > 500), a film, a layer on a support, image formation, or aqueous-alkaline development. Its substrates are low-molecular-weight, solution-phase compounds used as synthesis protecting groups.

Barltrop (1966) — same limitation, five years earlier: photocleavage of o-nitrobenzyl carbamates/esters to liberate an amino acid in aqueous solution at short-wavelength UV. Nothing about coatings or imaging.

US 3,615,629 — discloses a negative-working, free-radical photopolymerizable relief layer on a support. It teaches the conventionality of the article format (support + photosensitive organic layer + imagewise exposure + washout). It does not disclose any o-nitrocarbinol ester, any nitro-aromatic photocleavage, or any alkali-developable positive system. Its contribution to a § 103 combination is therefore thin.

Kosar (1967) — as characterized by the specification itself, positive-working plates then rested on photodecomposition of diazonium salts or o-quinone diazides, and were acknowledged to be thermally unstable and storage-poor. This is an applicant admission of both the state of the art and the motivation to replace that chemistry.

3. Element-by-element mapping (claims 1 and 2)

Claims 1 and 2 recite the same polymer chemistry and the same functional limitation; they differ only in article context (printing-plate support vs. substrate-to-be-etched). Any § 103 argument that defeats one defeats the other.

4. The combinations a challenger would assert

Combination A (strongest): Patchornik + Kosar/conventional plate art.
Rationale: Patchornik supplies every atom of formula I and the operative mechanism (light → free acid). Kosar/the admission supplies the article and the express motivation (existing positive systems are heat-labile; find a photolabile group that survives baking). Motivation to combine: (i) both address the same problem — making an organic film imagewise soluble; (ii) attaching a photolabile group to a polymer backbone was routine by 1971, given polymer-supported synthesis (Merrifield, 1963) and polymer-bound photoactive additives; (iii) the resist art already used polymeric binders plus low-MW photoactive compounds, and the known defect of that format — leaching/exudation of the low-MW component — is precisely what motivates covalent attachment; (iv) the photoreaction is intramolecular (the ortho-nitro group abstracts the benzylic hydrogen within the same chromophore), so a skilled artisan would reasonably expect it to survive the macromolecular context. The synthesis is a one-step half-esterification of a commercial styrene/maleic anhydride or (meth)acrylic copolymer with commercial o-nitrobenzyl alcohol — routine bench chemistry.

Combination B: Barltrop (1966) + Patchornik (1970) + Kosar.
Rationale: Barltrop shows the o-nitrobenzyl photocleavage was old by 1966 and known to release an amino acid (an alkali-soluble salt) in water; Patchornik shows the carboxylic-ester embodiment and the substituent variants. Motivation: same field, same scaffold, the later paper expressly improving the earlier, and a specific need (a stable photolabile group) that both papers satisfy.

Combination C: US 3,615,629 + Patchornik.
Rationale: 3,615,629 supplies the plate article and how such layers are coated and developed; Patchornik supplies the chemistry. Motivation: common assignee (both BASF) means the same R&D organization had both disclosures in hand — a classic "same company, combine its own two technologies" story. This combination is weak on the merits (see §6) and may be unavailable altogether.

Numeric limits. Even if the core were obvious, the challenger argues MW > 500 and ≥ 5 wt% are arbitrary floors; the specification itself says "polymers which contain more than 30 mol percent of units having o-nitrocarbinol ester groups are very suitable," which signals the floor is a matter of degree, not of kind. Under KSR, "a court must ask whether the improvement is more than the predictable use of prior art elements according to their established functions." Rarely will an arbitrary floor rescue a claim.

5. The nonobviousness case the patentee can mount

1. Different function / teaching away. Patchornik and Barltrop teach solution-phase deprotection of analytical quantities with short-wavelength (≈254 nm) light; both expressly deal with "liquid or crystalline" compounds (the specification's phrase). Neither discloses or suggests a coherent film, an image, or development with aqueous alkali. In re Gurley, 27 F.3d 551 (Fed. Cir. 1994) requires criticism or discouragement for true teaching away, so this is weaker than patentees usually assume — but the "different use/field of endeavor" argument has some traction because the references are peptide-synthesis papers, not imaging materials.
2. Unexpected results. The specification's core assertion is that in macromolecular form the reaction "proceeds uniformly" and the polymer "do[es] not enter into any kind of crosslinking reaction" — contrary to the expectation from nitro compounds' known propensity for radical formation, hydrogen abstraction, and obscure side reactions, which would crosslink the film and destroy the solubility differential. It also reports quantum yields of 0.01–1 and 10-day/170 °C thermal survival (Example 1c). In re Soni, 54 F.3d 746 (Fed. Cir. 1995) requires that objective evidence be commensurate in scope with the claims — and this evidence was generated on a handful of species, so a challenger will attack its reach across the full 5–14-membered aromatic/pyridine genus.
3. The functional limitation is a layer-level result, not merely a compound property — though functionality inherent in an obvious structure generally does not confer patentability.
4. Objective evidence (secondary considerations): ~238 forward-citing applications (IBM, Du Pont, Ciba-Geigy, Fuji, Affymetrix's US 5,143,854 among them), a long press life without lacquering, and later BASF family filings. Citation is not itself evidence of nonobviousness, and no commercial-success nexus is established in the record.

6. Threshold availability problem for US 3,615,629

This is worth stating precisely, because it materially weakens the strongest-looking combination:

• US 3,615,629 granted 1971-10-26, after the 10/12/1971 priority date, and not more than one year before the 10/05/1972 US filing — so it is not § 102(a) and not § 102(b) art.
• Its application (04/711,185, i.e., the 1968 series) predates the invention, so it can only be § 102(e) art.
• Both it and the patent under review were owned by Badische Anilin- & Soda-Fabrik AG. Pre-AIA § 103(c) provides that subject matter qualifying as prior art only under § 102(e), (f) or (g) shall not preclude patentability under § 103 where the subject matter and the claimed invention were commonly owned at the time the invention was made.

Caveat (I will not overstate this): § 103(c) was enacted in 1984, and I have not verified whether its temporal applicability reaches a patent granted in 1974. If it does not reach this patent, the common-ownership point is unavailable and 3,615,629 remains § 102(e) art. I could not resolve this within this session, and I flag it as an open question rather than a conclusion.

7. Bottom line

• No single reference anticipates claims 1 or 2. Patchornik and Barltrop teach the photochemistry but no polymer, no layer, no image; US 3,615,629 teaches the article but none of the chemistry.
• The realistic § 103 attack is a combination: Patchornik + the conventional positive-plate/resist art (Kosar, and the specification's own admissions), with Barltrop supplying the 1966 priority of the chemistry. Framed under KSR's "obvious to try" rubric — a small, enumerated set of known options (which carbinol; which unsaturated acid; polymerize the ester monomer vs. half-esterify an existing polymer), with a predicted outcome (light → free —COOH → alkali developability) — the claims are, in my assessment, more likely than not obvious, and the broad Markush genus (aromatic or pyridine, 5–14 members) magnifies that exposure.
• The patentee's best defense is not the chemistry (which is squarely old) but the article-level and macromolecular-level results — the clean, crosslink-free photoreaction in a solid film, the demonstrated 170 °C/10-day thermostability, and the alkali-developable positive image, which neither reference discloses, suggests, or even addresses. That is a genuine factual fight, not a formality.
• Practical posture: the patent expired 1991-11-19, so the analysis is academic. Presumption of validity under 35 U.S.C. § 282 and the clear-and-convincing standard of Microsoft v. i4i, 564 U.S. 91 (2011), would govern any litigation challenge; an IPR on an expired patent is theoretically possible but no such proceeding exists (per the earlier-generated litigation section).

8. Caveats and open gaps I could not close

1. I did not read the Patchornik (1970) or Barltrop (1966) papers themselves; I characterized them from the patent's own text and from the secondary photochemistry literature. The JACS paper's exact species list and any statement about polymers or imaging should be verified before relying on this analysis.
2. My search for pre-1971 art binding o-nitrobenzyl esters to a polymer (e.g., polymer-supported photolabile protecting groups) hit the search-step limit and was not completed. If such art exists, Combination A becomes materially stronger; if it does not, the patentee's "first to macromolecularize a known photochemistry" story improves. This is the single most important unresolved factual question.
3. Modern descriptions of o-nitrobenzyl photoresists that surfaced in searching (e.g., BenchChem documentation hubs) are contemporary secondary sources, not prior art, and I have not used them as such.
4. The temporal applicability of pre-AIA § 103(c) to a 1974-issued patent, and the exact filing date of US 3,615,629 (inferred as 1968 from application series 04/711,185), are unverified.
5. OCR corruption in the Google Patents capture (e.g., "0-nitro," "Onitrocarbinol," "EXAMPLE 1 il," mangled formula glyphs) has been flagged, not silently corrected, consistent with the prior sections of this file.