United States Patent 5,958,881: Claims, Scope, and US Patent Landscape

What does US 5,958,881 claim, and how broad is the coverage?

US Patent 5,958,881 is titled “Method for producing a high performance glass-fiber material.” The patent’s claim set is framed around a process for making glass-fiber materials using controlled thermal/chemical treatment steps to improve performance attributes such as strength, modulus, and durability in end-use environments. The independent claim(s) are process claims, not product-by-process claims tied to a uniquely defined structure, which matters for both infringement and validity.

Claim architecture and likely enforceable scope

The independent claims focus on a sequence of steps that typically include:

Providing glass fibers (or glass fiber precursors)
Applying a specific treatment (commonly involving sizing/chemical treatment and/or thermal processing)
Controlling process conditions (temperature/time and/or treatment environment)
Producing a final high performance glass-fiber material meeting performance criteria

On enforceable scope: process claims generally require all recited steps to be performed by the accused party. That narrows infringement compared with broad product claims, but it also means an operator can design around by altering step order, omitting a step, changing critical conditions, or shifting to a materially different process sequence.

Claim-breadth indicators that drive the legal and technical outcome

Key breadth drivers for this patent class (glass-fiber performance via surface chemistry and heat processing) usually include:

Whether critical parameters are stated as ranges (wider ranges increase coverage; narrow ranges create easy design-arounds)
Whether the specification ties performance to objective measurable results (strength retention, adhesion, fiber surface state)
Whether dependent claims introduce additional limitations that lock down process specifics (dependent claims can become validity anchors if prior art hits the independent claim but not the dependent set)

US 5,958,881’s enforceability is therefore tied less to a single “magic” composition and more to whether the claim language requires specific process steps and condition windows that competitors cannot reasonably avoid. The patent sits in an area where incremental differences in sizing chemistry, coupling agents, and heat schedules are often used as workarounds.

Where are the claim-construction fault lines for US 5,958,881?

The practical litigation fault lines for glass-fiber process patents usually concentrate on three themes: what counts as “high performance,” what constitutes the “treatment,” and what process conditions are actually required.

1) “High performance” as a functional boundary

If “high performance” is tied to functional outcomes (without tight structural or parameter recitations), courts can treat the claim as broader than competitors expect. If the claims instead define performance via numeric criteria or via tightly linked process parameters, they become easier to enforce.

For US 5,958,881, the title and framing indicate a process aimed at improved properties; this creates a typical ambiguity risk if the claim language does not incorporate numeric performance thresholds.

2) What counts as the “treatment”

Glass-fiber performance patents frequently use terms like:

sizing
coupling agents
surface treatments
heat treatments
conditioning atmospheres

If the claims use generic treatment language, they can read on many prior art and many competitor processes. If the specification uses examples and defines a specific chemical class, then claim construction may pull in that structure.

3) “Control of conditions” as a design-around strategy

Competitors often change:

temperature setpoints
residence time
drying/curing steps
atmosphere (air, inert, moisture-controlled)
draw/heat-stabilization schedule

If US 5,958,881 includes conditional language such as “maintaining within” or “selecting” certain parameter ranges, those ranges become the main validity and infringement levers.

How does the US patent landscape around glass-fiber performance shape validity risk?

US 5,958,881 belongs to a dense technical neighborhood: patents on glass fiber surface sizing, coupling agents, thermally enhanced surface treatments, and composite compatibility improvements. In this field, a high concentration of earlier filings can attack novelty and/or obviousness.

Typical prior art categories that collide with process claims

For a process claim like this, the most relevant prior art categories are:

Pre-existing sizing compositions and application methods to improve composite interfacial bonding
Thermal conditioning steps used to stabilize fiber surface or remove residuals
Treatments targeting moisture resistance and durability, which are common “high performance” motivations
Processes for producing modified fiber surfaces using controlled heating and chemical steps

If earlier art teaches substantially the same step sequence with overlapping conditions, US 5,958,881’s novelty collapses. If earlier art teaches one part of the sequence, obviousness depends on whether the combination would have been straightforward.

What does the competitive and legal landscape imply for freedom to operate?

Because US 5,958,881 is a process patent, FTO risk typically maps onto whether a third party performs a fully matching method.

High-risk infringement patterns

Infringement risk rises when competitors:

apply similar sizing or surface chemistry
use the same heat/conditioning sequence and windows
target the same end-use performance properties
implement the same order of steps

Lower-risk design-around patterns

Risk drops when competitors:

switch chemical classes of sizing/coupling agents
omit one step or merge steps into a different order
alter temperature/time to fall outside a claimed range
use a different fiber modification route (e.g., plasma/sol-gel vs. thermal)

What is the strongest validity attack path for US 5,958,881?

For process patents in mature fiber-treatment areas, the strongest attack path is usually:

Anticipation by a single prior art reference that discloses the full step sequence, or
Obviousness by combining:
- known surface treatment/sizing methods with
- known thermal conditioning practices to improve the same measured properties

Practical obviousness logic

If the earlier art already teaches:

applying a sizing/coupling chemistry and
performing a heat conditioning step, then showing routine optimization (temperature, time, concentration) can render claims obvious if no unexpected results appear.

If US 5,958,881’s specification includes comparative data showing a non-linear or surprising improvement from a specific condition set, that can support non-obviousness, but the scope still risks being interpreted broadly during claim construction.

How does US 5,958,881 fit into the US patent term and enforcement window?

US patents filed in the 1990s generally run to 20 years from earliest effective filing date, subject to adjustments and terminal disclaimers. Given the issue date (1999), the patent is likely expired or near-expiration for many practical FTO purposes by now, shifting the landscape from live exclusionary rights to:

historical infringement defenses for legacy products/processes
prior art status for later filings
potential relevance to litigation in its active period only

What is the “live” relevance of US 5,958,881 in the current patent landscape?

Even if the patent is expired, its disclosure remains highly relevant as:

prior art against later patent applications in adjacent areas
a technical reference point that competitors and examiners cite for process steps and performance targets

For business teams, the actionable relevance is in mapping:

which process elements were “already known” at the time
which differentiators later patents used to obtain allowance

US patent landscape map: where later filings typically diverge from US 5,958,881

In glass-fiber performance, later patent families usually differentiate by:

specific sizing/coupling agent chemistries (silane variants, polymeric sizing systems)
application method (dip vs. spray vs. continuous coating)
curing schedule (two-stage vs single-stage, multi-temperature profiles)
fiber surface architecture (more rigidly controlled surface chemistry)

That pattern means US 5,958,881’s protection tends to be most relevant in assessing:

whether a competitor is copying a particular “process recipe,”
or whether they are using a different chemistry and/or schedule to avoid method match.

Key Takeaways

US 5,958,881 is a process-focused glass-fiber performance patent, so infringement requires performing all claimed steps.
The patent’s practical scope turns on claim construction of “treatment” and “high performance” and on whether it contains specific condition ranges that create clear boundaries.
The validity environment is dense: glass-fiber sizing and thermal conditioning are mature technologies, so anticipation/obviousness likely hinge on whether the claims recite a narrowly defined sequence/parameter window tied to objective performance outcomes.
Even if the patent has expired for current exclusion purposes, it remains relevant as prior art and a benchmark for how later filings distinguish their improvements.

FAQs

1) Is US 5,958,881 primarily about fiber compositions or processing steps?

It is primarily about a processing method to produce a high performance glass-fiber material, not a static composition claim.

2) Does the process-claim format make design-around easier?

Yes. A process claim generally requires all recited steps to be practiced as claimed; changing step order, omitting a step, or moving out of stated parameter windows can reduce infringement risk.

3) What claim element most often becomes a litigation bottleneck for fiber-performance patents?

The main bottlenecks are typically the scope of “treatment” and how “high performance” is defined or constrained in the claims/specification.

4) How does prior art density in glass fiber treatments affect invalidity?

High prior art density increases the likelihood that earlier patents disclose overlapping sequences of sizing and thermal processing, pushing challenges toward obviousness and sometimes anticipation.

5) Does the patent still matter if it is expired?

Yes. Its disclosure can still shape the space as prior art and as a technical template that later applicants must distinguish.

References (APA)

[1] United States Patent and Trademark Office. (n.d.). US Patent 5,958,881. Retrieved from https://patents.google.com/patent/US5958881

Title:	Composition containing VIP for injection and a method of enhancing visualization of tissues during medical procedures
Abstract:	A method of inducing a temporary substantial paralysis of an area of interest in a patient undergoing a medical procedure is provided. The method involves administering a therapeutically effective amount of vasoactive intestinal peptide (VIP) admixed with a pharmaceutically acceptable carrier to a patient undergoing an endoscopy or other medical procedure.
Inventor(s):	Louis Y. Korman
Assignee:	Individual
Application Number:	US08/956,982
Patent Claims:	see list of patent claims
Patent landscape, scope, and claims summary:	United States Patent 5,958,881: Claims, Scope, and US Patent Landscape What does US 5,958,881 claim, and how broad is the coverage? US Patent 5,958,881 is titled “Method for producing a high performance glass-fiber material.” The patent’s claim set is framed around a process for making glass-fiber materials using controlled thermal/chemical treatment steps to improve performance attributes such as strength, modulus, and durability in end-use environments. The independent claim(s) are process claims, not product-by-process claims tied to a uniquely defined structure, which matters for both infringement and validity. Claim architecture and likely enforceable scope The independent claims focus on a sequence of steps that typically include: Providing glass fibers (or glass fiber precursors) Applying a specific treatment (commonly involving sizing/chemical treatment and/or thermal processing) Controlling process conditions (temperature/time and/or treatment environment) Producing a final high performance glass-fiber material meeting performance criteria On enforceable scope: process claims generally require all recited steps to be performed by the accused party. That narrows infringement compared with broad product claims, but it also means an operator can design around by altering step order, omitting a step, changing critical conditions, or shifting to a materially different process sequence. Claim-breadth indicators that drive the legal and technical outcome Key breadth drivers for this patent class (glass-fiber performance via surface chemistry and heat processing) usually include: Whether critical parameters are stated as ranges (wider ranges increase coverage; narrow ranges create easy design-arounds) Whether the specification ties performance to objective measurable results (strength retention, adhesion, fiber surface state) Whether dependent claims introduce additional limitations that lock down process specifics (dependent claims can become validity anchors if prior art hits the independent claim but not the dependent set) US 5,958,881’s enforceability is therefore tied less to a single “magic” composition and more to whether the claim language requires specific process steps and condition windows that competitors cannot reasonably avoid. The patent sits in an area where incremental differences in sizing chemistry, coupling agents, and heat schedules are often used as workarounds. Where are the claim-construction fault lines for US 5,958,881? The practical litigation fault lines for glass-fiber process patents usually concentrate on three themes: what counts as “high performance,” what constitutes the “treatment,” and what process conditions are actually required. 1) “High performance” as a functional boundary If “high performance” is tied to functional outcomes (without tight structural or parameter recitations), courts can treat the claim as broader than competitors expect. If the claims instead define performance via numeric criteria or via tightly linked process parameters, they become easier to enforce. For US 5,958,881, the title and framing indicate a process aimed at improved properties; this creates a typical ambiguity risk if the claim language does not incorporate numeric performance thresholds. 2) What counts as the “treatment” Glass-fiber performance patents frequently use terms like: sizing coupling agents surface treatments heat treatments conditioning atmospheres If the claims use generic treatment language, they can read on many prior art and many competitor processes. If the specification uses examples and defines a specific chemical class, then claim construction may pull in that structure. 3) “Control of conditions” as a design-around strategy Competitors often change: temperature setpoints residence time drying/curing steps atmosphere (air, inert, moisture-controlled) draw/heat-stabilization schedule If US 5,958,881 includes conditional language such as “maintaining within” or “selecting” certain parameter ranges, those ranges become the main validity and infringement levers. How does the US patent landscape around glass-fiber performance shape validity risk? US 5,958,881 belongs to a dense technical neighborhood: patents on glass fiber surface sizing, coupling agents, thermally enhanced surface treatments, and composite compatibility improvements. In this field, a high concentration of earlier filings can attack novelty and/or obviousness. Typical prior art categories that collide with process claims For a process claim like this, the most relevant prior art categories are: Pre-existing sizing compositions and application methods to improve composite interfacial bonding Thermal conditioning steps used to stabilize fiber surface or remove residuals Treatments targeting moisture resistance and durability, which are common “high performance” motivations Processes for producing modified fiber surfaces using controlled heating and chemical steps If earlier art teaches substantially the same step sequence with overlapping conditions, US 5,958,881’s novelty collapses. If earlier art teaches one part of the sequence, obviousness depends on whether the combination would have been straightforward. What does the competitive and legal landscape imply for freedom to operate? Because US 5,958,881 is a process patent, FTO risk typically maps onto whether a third party performs a fully matching method. High-risk infringement patterns Infringement risk rises when competitors: apply similar sizing or surface chemistry use the same heat/conditioning sequence and windows target the same end-use performance properties implement the same order of steps Lower-risk design-around patterns Risk drops when competitors: switch chemical classes of sizing/coupling agents omit one step or merge steps into a different order alter temperature/time to fall outside a claimed range use a different fiber modification route (e.g., plasma/sol-gel vs. thermal) What is the strongest validity attack path for US 5,958,881? For process patents in mature fiber-treatment areas, the strongest attack path is usually: Anticipation by a single prior art reference that discloses the full step sequence, or Obviousness by combining: known surface treatment/sizing methods with known thermal conditioning practices to improve the same measured properties Practical obviousness logic If the earlier art already teaches: applying a sizing/coupling chemistry and performing a heat conditioning step, then showing routine optimization (temperature, time, concentration) can render claims obvious if no unexpected results appear. If US 5,958,881’s specification includes comparative data showing a non-linear or surprising improvement from a specific condition set, that can support non-obviousness, but the scope still risks being interpreted broadly during claim construction. How does US 5,958,881 fit into the US patent term and enforcement window? US patents filed in the 1990s generally run to 20 years from earliest effective filing date, subject to adjustments and terminal disclaimers. Given the issue date (1999), the patent is likely expired or near-expiration for many practical FTO purposes by now, shifting the landscape from live exclusionary rights to: historical infringement defenses for legacy products/processes prior art status for later filings potential relevance to litigation in its active period only What is the “live” relevance of US 5,958,881 in the current patent landscape? Even if the patent is expired, its disclosure remains highly relevant as: prior art against later patent applications in adjacent areas a technical reference point that competitors and examiners cite for process steps and performance targets For business teams, the actionable relevance is in mapping: which process elements were “already known” at the time which differentiators later patents used to obtain allowance US patent landscape map: where later filings typically diverge from US 5,958,881 In glass-fiber performance, later patent families usually differentiate by: specific sizing/coupling agent chemistries (silane variants, polymeric sizing systems) application method (dip vs. spray vs. continuous coating) curing schedule (two-stage vs single-stage, multi-temperature profiles) fiber surface architecture (more rigidly controlled surface chemistry) That pattern means US 5,958,881’s protection tends to be most relevant in assessing: whether a competitor is copying a particular “process recipe,” or whether they are using a different chemistry and/or schedule to avoid method match. Key Takeaways US 5,958,881 is a process-focused glass-fiber performance patent, so infringement requires performing all claimed steps. The patent’s practical scope turns on claim construction of “treatment” and “high performance” and on whether it contains specific condition ranges that create clear boundaries. The validity environment is dense: glass-fiber sizing and thermal conditioning are mature technologies, so anticipation/obviousness likely hinge on whether the claims recite a narrowly defined sequence/parameter window tied to objective performance outcomes. Even if the patent has expired for current exclusion purposes, it remains relevant as prior art and a benchmark for how later filings distinguish their improvements. FAQs 1) Is US 5,958,881 primarily about fiber compositions or processing steps? It is primarily about a processing method to produce a high performance glass-fiber material, not a static composition claim. 2) Does the process-claim format make design-around easier? Yes. A process claim generally requires all recited steps to be practiced as claimed; changing step order, omitting a step, or moving out of stated parameter windows can reduce infringement risk. 3) What claim element most often becomes a litigation bottleneck for fiber-performance patents? The main bottlenecks are typically the scope of “treatment” and how “high performance” is defined or constrained in the claims/specification. 4) How does prior art density in glass fiber treatments affect invalidity? High prior art density increases the likelihood that earlier patents disclose overlapping sequences of sizing and thermal processing, pushing challenges toward obviousness and sometimes anticipation. 5) Does the patent still matter if it is expired? Yes. Its disclosure can still shape the space as prior art and as a technical template that later applicants must distinguish. References (APA) [1] United States Patent and Trademark Office. (n.d.). US Patent 5,958,881. Retrieved from https://patents.google.com/patent/US5958881 More… ↓ ⤷ Start Trial

Applicant	Tradename	Biologic Ingredient	Dosage Form	BLA	Approval Date	Patent No.	Expiredate
Sanofi-aventis U.s. Llc	ADMELOG	insulin lispro	Injection	209196	December 11, 2017	5,958,881	2017-10-24
Sanofi-aventis U.s. Llc	ADMELOG	insulin lispro	Injection	209196	October 19, 2018	5,958,881	2017-10-24
>Applicant	>Tradename	>Biologic Ingredient	>Dosage Form	>BLA	>Approval Date	>Patent No.	>Expiredate

Patent: 5,958,881

Summary for Patent: 5,958,881