Laminated Latex Films Segmentation for Skin Compatibility

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Solution Overview

Problem

There is a need for improved methods to produce rubber latex articles that balance strength, chemical resistance, and suitability for applications like gloves and condoms, while avoiding the allergic reactions associated with natural rubber and the limitations of synthetic materials without cross-linking systems.

Innovation Solution

A method involving the formation of laminated articles using a dip-molding process with layers of latex compositions, one containing a vulcanizer component and the other without, where the layer without the vulcanizer is in contact with the skin and the vulcanizer-containing layer is on the outside, and the articles are cured between 90°C to 140°C to achieve superior physical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If natural rubber latex is used for glove and condom manufacture, then excellent physical properties and flexibility are achieved, but Type I hypersensitivity and allergic reactions occur due to proteins in natural rubber

Engineering Contradiction:
Improvephysical propertiesVSAvoidallergic reactions
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent extracts and removes the harmful protein components from natural rubber latex through a purification process, creating a purified latex composition that maintains the desirable physical properties while eliminating the allergenic proteins that cause Type I hypersensitivity reactions

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent creates a composite material by combining purified natural rubber latex with synthetic polyisoprene latex in a laminated structure. This composite approach maintains the flexibility and physical properties of natural rubber while eliminating allergic reactions through the use of synthetic components in the inner layer

Inventive Principle:
Principle #40Composite materials

2Duration of action of stationary object

If synthetic isoprene polymer is converted into a more durable material by vulcanization with sulfur and activator/accelerator system, then durability and strength are improved, but the article requires cross-linking and curing systems that may cause skin sensitivity

Engineering Contradiction:
ImprovedurabilityVSAvoidskin sensitivity
Core Design Contradiction:
Duration of action of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent segments the vulcanization system into separate layers: the outer layer contains sulfur, activator, and accelerator components for vulcanization and durability, while the inner layer is free from these components to prevent skin sensitivity. This segmentation allows the article to achieve both durability and skin compatibility

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies different compositional qualities to different parts of the article: the outer layer is formulated with vulcanizing agents for durability and chemical resistance, while the inner layer in contact with skin is formulated without these agents to provide hypoallergenic properties, thus each part has the quality suited to its function

Inventive Principle:
Principle #3Local quality

3Object-affected harmful factors

If synthetic materials free of vulcanizers and accelerators are used, then skin sensitivity is minimized, but resistance to certain classes of chemicals is reduced

Engineering Contradiction:
Improveskin sensitivityVSAvoidchemical resistance
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent segments the functional properties into separate layers: the inner layer provides skin compatibility by being free of vulcanizers and accelerators, while the outer layer provides chemical resistance through the inclusion of these components, thus both requirements are satisfied in different parts of the same article

Inventive Principle:
Principle #1Segmentation

4Reliability

If a laminated film structure with inner layer free of vulcanizer and outer layer containing vulcanizer is created, then both skin compatibility and chemical resistance are achieved, but the manufacturing process complexity increases

Engineering Contradiction:
Improveskin compatibility and chemical resistanceVSAvoidmanufacturing process
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by preparing and coating the inner layer with purified latex free of vulcanizers first, then subsequently applying the outer layer containing the vulcanization system. This sequential preliminary preparation simplifies the overall manufacturing process by establishing the skin-compatible base layer before adding the protective outer layer

Inventive Principle:
Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The method results in articles with enhanced strength and chemical resistance, minimizing skin sensitivity and ensuring the vulcanizer layer is not in contact with sensitive skin, thus addressing the limitations of existing synthetic materials.

Implementation Method 1

dipping the mold into a first latex composition containing a vulcanizer component selected from sulfur, organic peroxide, vulcanizing activator, vulcanizing accelerator, and mixtures thereof, forming a first layer

Methodology Applied
Scientific EffectDeposition: Deposition (physical)

Implementation Method 2

dipping the mold having the first layer formed thereon into a second latex composition free of the vulcanizer component, forming a laminated film with a second layer formed on the first layer

Methodology Applied
Scientific EffectDeposition: Deposition (physical)

Implementation Method 3

curing the laminated film by heating to a temperature between 90° C. to 140° C.

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 4

the synthetic isoprene polymer is converted into a more durable material by vulcanization, with the addition of a curing system, e.g., sulphur, an activator/accelerator system

Methodology Applied
Scientific EffectVulcanization: Chemical Bonding

Data Source

PatentUS11931931B2Laminated films and methods of making and using same
Publication Date: 2024.03.19 CARIFLEX PTE LTD

AI summary

An article comprises a laminate with a layer comprising a first latex composition containing a cross-linker component selected from sulfur, organic peroxide, vulcanizing activators, and vulcanizing accelerator; and a second layer comprising a second latex composition free of the cross-linker component. The laminate is formed by dipping a mold into the first latex composition then into the second latex composition forming a laminated film, then curing the laminated film by heating to a temperature between 90° C. to 140° C. Lastly, the laminated film is removed from the mold via inversion such that the second layer is inwards and the first layer is outwards.