Aqueous Rubber Adhesive with Solvent-Induced Swelling

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Solution Overview

Problem

Existing solvent-based adhesives for rubber products pose environmental and health hazards due to high volatile organic compound (VOC) emissions, and aqueous adhesives lack sufficient adhesive strength, leading to adhesion failures.

Innovation Solution

An aqueous adhesive comprising rubber latex as the main component and an organic solvent that causes swelling of the rubber component, with specific solvent and solid content concentrations, improves affinity and adhesive strength through vulcanization reaction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a solvent-based adhesive is used to achieve sufficient adhesive strength, then adhesive strength is improved, but VOC emissions and environmental harm increase

Engineering Contradiction:
Improveadhesive strengthVSAvoidVOC emissions
Core Design Contradiction:
StrengthVSObject-generated harmful factors

Solution Approach 1:

The invention changes the solvent system from organic to aqueous, fundamentally altering the chemical composition parameters. The adhesive uses water as the primary solvent instead of organic solvents like naphtha, thereby eliminating VOC emissions while maintaining adhesive functionality through the aqueous-based rubber latex formulation

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite adhesive system combining rubber latex, aqueous solution, and specific additives (vulcanization accelerator, filler, plasticizer) to achieve the necessary adhesive properties. This composite formulation replaces the simple organic solvent-based system while maintaining or improving adhesive performance without the harmful emissions

Inventive Principle:
Principle #40Composite materials

2Object-generated harmful factors

If an aqueous adhesive is used to reduce VOC emissions, then environmental harm is reduced, but adhesive strength becomes insufficient

Engineering Contradiction:
ImproveVOC emissionsVSAvoidadhesive strength
Core Design Contradiction:
Object-generated harmful factorsVSStrength

Solution Approach 1:

The invention adjusts critical parameters of the aqueous adhesive including solid content concentration (30-70%), pH value (7-12), and additive ratios to optimize adhesive performance. These parameter optimizations ensure that the aqueous adhesive achieves sufficient bonding strength for rubber-to-rubber applications

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention introduces specific intermediary substances including vulcanization accelerators (e.g., CBS, MBT) and fillers that facilitate the bonding process between rubber surfaces. These intermediaries enable the aqueous adhesive to achieve adequate adhesion strength by promoting cross-linking and bonding reactions at the interface

Inventive Principle:
Principle #24Intermediary (Mediator)

3Strength

If the solid content concentration in the base agent is increased to improve adhesive strength, then adhesive strength is improved, but viscosity increases making application difficult

Engineering Contradiction:
Improveadhesive strengthVSAvoidapplication ease
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The invention optimizes the solid content concentration within the specific range of 30-70%, balancing adhesive strength and application properties. This parameter optimization ensures the adhesive has sufficient solids for strong bonding while maintaining manageable viscosity for practical application

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses plasticizers as intermediary substances to modify the rheological properties of the adhesive. These plasticizers reduce viscosity and improve flow characteristics, making the adhesive easier to apply while the high solid content provides the necessary bonding strength

Inventive Principle:
Principle #24Intermediary (Mediator)

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 adhesive achieves stable and strong bonding between rubber materials with reduced VOC emissions, minimizing environmental and health risks while maintaining effective adhesion.

Implementation Method 1

an organic solvent that causes swelling of a rubber component in the rubber latex

Methodology Applied
Scientific EffectSwelling:

Implementation Method 2

improves affinity and adhesive strength through vulcanization reaction

Methodology Applied
Scientific EffectVulcanization:

Data Source

PatentEP4119629B1Aqueous adhesive for rubber
Publication Date: 2025.10.22 SUMITOMO RUBBER INDUSTRIES LTD
  • EP4119629B1 patent drawingFigure 1
  • EP4119629B1 patent drawingFigure 2A~2B

AI summary

An aqueous adhesive for rubber of the present disclosure includes: a base agent containing rubber latex as a main component thereof; and an organic solvent that causes swelling of a rubber component in the rubber latex. An amount of the organic solvent in the aqueous adhesive for rubber is not less than 25% by mass and not greater than 60% by mass of a total amount of the base agent and the organic solvent. A boiling point of the organic solvent is preferably not higher than 140°C. A tennis ball of the present disclosure includes a hollow core made of a rubber material. The hollow core includes two hemispherical half cores. The two half cores are adhered to each other by using the aqueous adhesive for rubber.