Method for producing semi-IPN composite and method for producing synthetic leather

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Solution Overview

Problem

Existing materials for synthetic leathers lack effective stain resistance without using expensive and potentially harmful fluorine compounds, and existing methods for producing semi-IPN composites do not achieve optimal stain resistance when using aromatic polyisocyanates.

Innovation Solution

A method for producing a semi-IPN composite by polymerizing hydrophilic monofunctional acrylate and polyfunctional acrylate in a solution of polyurethane prepared using aliphatic or alicyclic polyisocyanates, incorporating amido and oxyethylene group-containing acrylic monomers to achieve excellent stain resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If fluorine compounds are added to polyurethane solution to achieve stain resistance, then stain resistance is improved, but cost increases and harmful effects on human body occur

Engineering Contradiction:

Improvestain resistanceVSAvoidharmful effects on human body

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces expensive fluorine compounds with a cost-effective semi-IPN composite system consisting of polyurethane and hydrophilic polymer. The hydrophilic polymer network provides stain resistance through its water-loving properties rather than through fluorine-based hydrophobic effects, achieving the same protective function at lower cost and without harmful effects.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent creates a semi-IPN (interpenetrating polymer network) composite material combining polyurethane with hydrophilic polymer formed from monofunctional and polyfunctional acrylates. This composite structure integrates the mechanical properties of polyurethane with the stain-resistant properties of hydrophilic polymer, achieving superior performance without fluorine compounds.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If aromatic polyisocyanate is used in semi-IPN composite production, then manufacturing process is simplified, but stain resistance is insufficient

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidstain resistance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent changes the chemical parameter of the polyisocyanate from aromatic to aliphatic or alicyclic type. This parameter change fundamentally alters the properties of the resulting semi-IPN composite, enabling both excellent stain resistance and good flexibility to be achieved simultaneously, whereas aromatic polyisocyanates could not provide adequate stain resistance.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If hydrophobic monomers are used in polymerization, then oil resistance is improved, but flexibility and mechanical strength deteriorate

Engineering Contradiction:

Improveoil resistanceVSAvoidflexibility and mechanical strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent inverts the conventional approach by using hydrophilic monomers instead of hydrophobic monomers. Rather than making the polymer surface hydrophobic to repel oil, the patent creates a hydrophilic polymer network that selectively interacts with water-based substances, achieving oil resistance through hydrophilicity while maintaining flexibility and mechanical strength.

Inventive Principle:

Principle #13The other way round (Inversion)

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 resulting semi-IPN composite exhibits superior stain resistance, making it suitable for skin and topcoat layers of synthetic leathers, particularly for vehicles, while avoiding the use of fluorine compounds and ensuring uniform distribution of hydrophilic components for enhanced performance.

Implementation Method 1

polymerizing a hydrophilic monofunctional acrylate (b1) and a polyfunctional acrylate (b2) in a solution of a polyurethane (A)

Methodology Applied

Scientific EffectFree-radical polymerization: Photopolymerisation

Data Source

PatentEP3375794B1Method for producing semi-IPN composite and method for producing synthetic leather

Publication Date: 2022.10.26 DIC CORP

AI summary

The present invention relates to a method for producing a semi-IPN composite, the method including polymerizing a hydrophilic monofunctional acrylate (b1) and a polyfunctional acrylate (b2) in a solution of a polyurethane (A) prepared using an aliphatic polyisocyanate and/or an alicyclic polyisocyanate as a raw material. The present invention also relates to a method for producing a synthetic leather that includes a layer obtained by drying the semi-IPN composite obtained by the above production method. One object of the present invention is to provide a method for producing a semi-IPN composite excellent in stain resistance. The semi-INP composite obtained by the production method of the present invention is excellent in stain resistance. Therefore, the semi-IPN composite can be used particularly preferably for skin and topcoat layers of synthetic leathers for vehicles.