Nitrile Rubber Closed-Cell Foam Sealing Material

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Solution Overview

Problem

Existing waterproof sealing materials, such as rubber-based resin closed-cell foam sheets, face challenges with reduced sealing capability over time due to decreased repulsive force and poor adhesion properties, leading to inadequate waterproofing, especially when compression flexibility is low or when open-cell foams allow water passage.

Innovation Solution

A rubber-based resin closed-cell foam sheet with 30% or more acrylonitrile content, combined with a preferred acrylonitrile butadiene rubber and optional liquid acrylonitrile butadiene rubber, is used, featuring a high closed-cell ratio and optimized for compression flexibility and adhesion, with ionizing radiation cross-linking and specific additives to enhance durability and resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If closed-cell foam is used to improve waterproofing capability, then water resistance is improved, but compression flexibility deteriorates

Engineering Contradiction:
Improvewaterproofing capabilityVSAvoidcompression flexibility
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent changes the chemical composition parameters of the rubber-based resin by specifying acrylonitrile content of 30-50% by weight, which fundamentally alters the material's properties to simultaneously achieve both closed-cell structure benefits and improved compression flexibility

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses composite material construction by combining rubber-based resin with specific additives (silica, alumina, calcium carbonate) and controlling the foam structure, creating a material that integrates the advantages of both closed-cell waterproofing and flexible compression recovery

Inventive Principle:
Principle #40Composite materials

2Ease of manufacture

If rubber-based resin with low acrylonitrile content is used, then processing ease is improved, but adhesion property and sealing capability deteriorate

Engineering Contradiction:
Improveprocessing easeVSAvoidadhesion property
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent establishes specific parameter ranges for acrylonitrile content (30-50% by weight) that optimize the balance between processing characteristics and adhesion properties, ensuring both ease of manufacture and reliable sealing capability

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If open-cell foam is used to improve compression flexibility, then compression flexibility is improved, but waterproofing capability deteriorates

Engineering Contradiction:
Improvecompression flexibilityVSAvoidwaterproofing capability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent applies local quality by creating a closed-cell foam structure that provides waterproofing in the bulk material while maintaining localized flexibility through the rubber-based resin composition and controlled cell structure

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the fundamental structure parameter from open-cell to closed-cell foam while adjusting the rubber-based resin composition to maintain compression flexibility, thereby achieving both waterproofing and flexibility

Inventive Principle:
Principle #35Parameter changes

4Reliability

If fixed-form sealing material with cell skin is used, then initial waterproofing is improved, but long-term sealing capability deteriorates

Engineering Contradiction:
Improveinitial waterproofingVSAvoidlong-term sealing capability
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent ensures continuity of useful action by using a closed-cell foam structure that maintains its waterproofing capability over time without the degradation issues of fixed-form materials, allowing sustained sealing performance throughout the product lifecycle

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The patent changes the material composition parameters by using rubber-based resin with 30-50% acrylonitrile content, which provides long-term stability and maintains sealing capability over extended periods without the degradation problems of alternative materials

Inventive Principle:
Principle #35Parameter changes

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 foam sheet maintains excellent sealing capability and compression flexibility, preventing deformation and water passage, ensuring high and sustained waterproofing performance even after prolonged use.

Implementation Method 1

A rubber-based resin is required to have not a liquid state but a rubber elasticity at 20° Celsius and one atmospheric pressure (1.01×10−1 MPa)

Methodology Applied
Scientific EffectRubber elasticity: Elasticity

Implementation Method 2

the foam sheet includes a rubber-based resin containing 30% or more by weight of acrylonitrile ingredient... maintaining excellent sealing capability and compression flexibility, preventing deformation and water passage

Methodology Applied
Scientific EffectPhysical barrier: Physical Containment

Data Source

PatentUS8835520B2Rubber-based resin closed-cell foam sheet and process for producing the same
Publication Date: 2014.09.16 SEKISUI CHEMICAL CO LTD

AI summary

The present invention provides a rubber-based resin closed-cell foam sheet with its sealing capability being unlikely to be lowered even for a prolonged period of use, and with its excellent waterproofing capability. The inventive rubber-based resin closed-cell foam sheet is characterized in that the foam sheet includes a rubber-based resin containing a nitrile group, and exhibits an excellent adhesion. When used as a waterproof sealing material, the foam sheet can adhere, in a tightly close contact, to the interface of a portion to be sealed. Therefore, the inventive rubber-based resin closed-cell foam sheet can be advantageously used as a waterproof sealing material having high sealing capability and excellent waterproofing capability.