Graft Polymerization for Elastic Body Surface Modification

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Solution Overview

Problem

Existing surface modification methods for rubber and thermoplastic elastomers, such as those used in syringe gaskets and tires, face challenges in balancing sliding properties and biocompatibility while being cost-effective, as they often rely on expensive materials like PTFE films that are not durable and cannot be sterilized by radiation.

Innovation Solution

A surface modification method involving the formation of polymerization initiation points on the surface, followed by radical polymerization of non-functional and fluorine-containing functional monomers to grow non-functional and fluorine-containing polymer chains, respectively, creating a polymer layer with desired functions like sliding properties and biocompatibility at a lower cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a sliding property improving agent (e.g., silicone oil) is applied to the sliding surface, then sliding properties are improved, but biocompatibility is compromised due to potential adverse effects on bio-preparations

Engineering Contradiction:
Improvesliding propertiesVSAvoidbiocompatibility
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent replaces expensive PTFE films with a cost-effective surface modification approach using graft polymerization. The modified surface provides sliding properties through a polymer layer containing hydrophobic and hydrophilic groups, eliminating the need for expensive PTFE while maintaining functionality and enabling radiation sterilization.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent creates a composite surface structure by grafting copolymer chains containing both hydrophobic groups (providing sliding properties) and hydrophilic groups (providing biocompatibility). This composite polymer structure simultaneously delivers both required properties without using silicone oil or PTFE.

Inventive Principle:
Principle #40Composite materials

2Ease of operation

If PTFE films are used to provide sliding properties, then sliding performance is improved, but production cost increases due to expensive materials

Engineering Contradiction:
Improvesliding propertiesVSAvoidproduction cost
Core Design Contradiction:
Ease of operationVSEase of manufacture

Solution Approach 1:

The patent replaces expensive PTFE films with a cost-effective surface modification approach using graft polymerization. The modified surface provides sliding properties through a polymer layer containing hydrophobic and hydrophilic groups, eliminating the need for expensive PTFE while maintaining functionality and enabling radiation sterilization.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Ease of operation

If PTFE films are used for surface modification, then sliding properties are improved, but durability is reduced due to poor performance under repeated sliding motion

Engineering Contradiction:
Improvesliding propertiesVSAvoiddurability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent performs preliminary surface modification by forming polymerization initiation points on the elastic body surface before final use. This preliminary graft polymerization creates a durable, crosslinked polymer layer that is integrated into the substrate, providing long-lasting sliding properties that withstand repeated motion better than applied PTFE films.

Inventive Principle:
Principle #10Preliminary action

4Ease of operation

If PTFE is used for surface coating, then sliding properties are improved, but sterilization capability is lost due to vulnerability to radiation

Engineering Contradiction:
Improvesliding propertiesVSAvoidsterilization capability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent replaces expensive PTFE films with a cost-effective surface modification approach using graft polymerization. The modified surface provides sliding properties through a polymer layer containing hydrophobic and hydrophilic groups, eliminating the need for expensive PTFE while maintaining functionality and enabling radiation sterilization.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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

This method effectively imparts sliding properties and biocompatibility to the surface of elastic bodies like gaskets and tires, reducing friction and water resistance while maintaining sealing properties, and is economically advantageous by minimizing the use of expensive functional monomers.

Implementation Method 1

step 1 of forming polymerization initiation points on a surface of the object; wherein the object is a rubber vulcanizate or a thermoplastic elastomer

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Implementation Method 2

step 2 of radically polymerizing a non-functional monomer, starting from the polymerization initiation points, to grow non-functional polymer chains, and further radically polymerizing a fluorine-containing functional monomer to grow fluorine-containing functional polymer chains

Methodology Applied
Scientific EffectRadical polymerization:

Data Source

PatentEP2894191B1Surface modification method and surface-modified elastic body
Publication Date: 2020.03.18 SUMITOMO RUBBER INDUSTRIES LTD
  • EP2894191B1 patent drawingFigure 1~2
  • EP2894191B1 patent drawingFigure 3~4
  • EP2894191B1 patent drawingFigure 5

AI summary

The present invention aims to provide methods for surface-modifying a rubber vulcanizate or a thermoplastic elastomer, which can cost-effectively impart a variety of functions, such as sliding properties or biocompatibility, according to the application. The present invention relates to a method for surface-modifying an object of a rubber vulcanizate or a thermoplastic elastomer, the method including: step 1 of forming polymerization initiation points A on the surface of the object; and step 2 of radically polymerizing a non-functional monomer, starting from the polymerization initiation points A, to grow non-functional polymer chains, and further radically polymerizing a fluorine-containing functional monomer to grow fluorine-containing functional polymer chains.