Cellulose Nanocrystal–Sulfonated Polyester Films for Warm-Water Removal

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Solution Overview

Problem

Conventional film-forming personal care products are difficult to remove without causing skin discomfort or requiring additional chemical substances, leading to waste and expense.

Innovation Solution

Aqueous mixtures comprising cellulose nanocrystals and sulfonated polyester, where the glass transition temperature of the sulfonated polyester is greater than 25°C, providing a film that is hydrophobic and resilient against water at room temperature, allowing easy removal with warm water without abrasion or oils.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional film-forming personal care products are used, then film formation and water resistance are achieved, but removal requires excessive mechanical abrasion or additional chemical substances

Engineering Contradiction:

Improvewater resistanceVSAvoidremoval ease

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent changes the chemical composition parameters of the film-forming mixture by incorporating cellulose nanocrystals and sulfonated polyester with specific glass transition temperatures. This creates a film that maintains water resistance through its cross-linked structure but allows controlled removal through thermal response at body temperature, eliminating the need for harsh abrasion or additional chemicals.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If oil-based removal products are used, then removal effectiveness is improved, but expense and environmental impact increase

Engineering Contradiction:

Improveremoval effectivenessVSAvoidwaste generation

Core Design Contradiction:

Ease of operationVSLoss of substance

Solution Approach 1:

The patent enables the film to be self-removable through a designed thermal response mechanism. The specific composition of cellulose nanocrystals and sulfonated polyester with Tg > 25°C allows the film to naturally detach when exposed to warm water or body heat, eliminating the need for oil-based removal products and reducing chemical waste.

Inventive Principle:

Principle #25Self-service

3Ease of operation

If mechanical abrasion is used for removal, then film removal is achieved, but skin discomfort and damage occur

Engineering Contradiction:

Improveremoval capabilityVSAvoidskin damage

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical removal system (abrasion) with a chemical-thermal system. The film's specific composition responds to thermal energy from warm water or body heat, causing controlled dissolution or detachment of the film matrix, thereby removing the film without mechanical contact that could damage the skin.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Ease of operation

If additional chemical substances are applied for removal, then removal completeness is improved, but skin exposure to chemicals increases

Engineering Contradiction:

Improveremoval completenessVSAvoidchemical exposure

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent designs the film composition to be self-removable through its inherent thermal response properties. The cellulose nanocrystal-sulfonated polyester matrix naturally detaches in warm water without requiring additional chemical agents, thereby ensuring complete removal while minimizing chemical exposure to the skin.

Inventive Principle:

Principle #25Self-service

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 mixture offers a comfortable and efficient removal process for cosmetic applications, reducing environmental impact and eliminating the need for abrasive or oil-based removal methods.

Implementation Method 1

the glass transition temperature (Tg) of the sulfonated polyester is greater than 25° C.

Methodology Applied

Scientific EffectGlass transition:

Implementation Method 2

providing a film that is hydrophobic and resilient against water at room temperature

Methodology Applied

Scientific EffectHydrophobicity: Hydrophobe

Implementation Method 3

allowing easy removal with warm water without abrasion or oils

Methodology Applied

Scientific EffectThermal softening:

Data Source

PatentUS12433832B2Aqueous mixtures comprising cellulose nanocrystals and sulfonated polyester

Publication Date: 2025.10.07 NORTH CAROLINA STATE UNIV

AI summary

Aqueous mixtures can include cellulose nanocrystals and sulfonated polyester, where a glass transition temperature (Tg) of the sulfonated polyester is greater than 25° C. In some instances, exemplary aqueous mixtures also include one or more additives, such as pigment. Exemplary aqueous mixtures can be applied as a film that is typically hydrophobic and resilient against water at room temperature. Upon application of warm water, such as at temperatures of from about 30° C. to about 60° C., the film can be removed with no or limited abrasion and/or with no or little removal oils.