Repair Patch Bimodal Natural Rubber Adhesion

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Solution Overview

Problem

Existing repair methods for vehicle tires face challenges in achieving a secure and permanent bond between the tire and repair patch, particularly due to the use of solvents in adhesives, which pose environmental and health risks, and require time-consuming solvent flashing off processes, and struggle to adjust adhesive and load strength according to varying tire casings and damage areas.

Innovation Solution

A repair patch with a connecting layer containing a mixture of two natural rubber components with bimodal molecular weight distribution, allowing for adjustable adhesion and load strength, and incorporating a filler system with precipitated silica and sulfur, which can be crosslinked during vulcanization, and an optional intermediate layer with fibrous inserts for structural reinforcement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If solvent-based adhesives are used to bond the repair patch to the tire, then initial adhesion is achieved, but environmental and health risks increase and time-consuming solvent evaporation is required

Engineering Contradiction:
Improveadhesive strengthVSAvoidenvironmental and health risks
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent removes the harmful solvent component from the adhesive system entirely, replacing it with a solvent-free rubber compound formulation that achieves bonding through direct vulcanization chemistry rather than solvent-based adhesion followed by evaporation

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The bonding layer uses a dual-cure vulcanization system that can proceed through both chemical crosslinking mechanisms simultaneously, allowing the adhesive to cure and achieve full strength without requiring solvent evaporation, fundamentally changing the curing parameter from evaporative to purely chemical

Inventive Principle:
Principle #35Parameter changes

2Strength

If solvent-based adhesives are used, then initial adhesion is achieved, but the bonding process becomes time-consuming due to solvent evaporation requirements

Engineering Contradiction:
Improveadhesive strengthVSAvoidsolvent evaporation time
Core Design Contradiction:
StrengthVSLoss of time

Solution Approach 1:

The patent eliminates the solvent evaporation step entirely by using a solvent-free adhesive formulation that cures through vulcanization chemistry, reducing the bonding process to a single concurrent chemical reaction step

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The adhesive formulation combines multiple functional components (rubber base, crosslinking agents, accelerators) into a single integrated system that performs both adhesion and structural bonding through one vulcanization process, eliminating the need for separate evaporation and curing steps

Inventive Principle:
Principle #5Merging (Combining)

3Strength

If conventional bonding layers are used, then standard adhesion is achieved, but the bond strength cannot be adjusted for different tire casings and damage areas

Engineering Contradiction:
Improvebond strengthVSAvoidadaptability to different tire casings
Core Design Contradiction:
StrengthVSAdaptability or versatility

Solution Approach 1:

The bonding layer formulation is designed with adjustable compositional parameters (rubber type ratios, crosslinking density, filler content) that can be dynamically modified to match the specific mechanical and chemical properties of different tire casings and damage severities

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent enables tailoring of the bonding layer's chemical and physical properties to match the local requirements of different tire regions (tread, sidewall, bead) and damage types, creating a customized bond strength profile for each application scenario

Inventive Principle:
Principle #3Local quality

4Object-generated harmful factors

If the adhesive is allowed to dry for too long, then solvent evaporation is complete, but adhesion is compromised due to overdrying

Engineering Contradiction:
Improvesolvent evaporation completenessVSAvoidadhesion
Core Design Contradiction:
Object-generated harmful factorsVSStrength

Solution Approach 1:

The patent removes the solvent component entirely from the adhesive system, eliminating the overdrying problem that occurs when solvent-based adhesives are left to evaporate too long, as there is no solvent to evaporate or over-evaporate

Inventive Principle:
Principle #2Taking out (Extraction)

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 bimodal molecular weight distribution of the natural rubber components enhances adhesion and structural resistance, enabling a secure bond that adapts to different tire casings and damage areas, while eliminating the need for solvent-based adhesives, thus improving safety and efficiency in tire repair.

Implementation Method 1

the first natural rubber component has a lower molecular weight (MW) than the second natural rubber component, such that a mixture of the first and second natural rubber components exhibits a bimodal molecular weight distribution

Methodology Applied
Scientific EffectBimodal molecular weight distribution:

Implementation Method 2

incorporating a filler system with precipitated silica and sulfur, which can be crosslinked during vulcanization

Methodology Applied
Scientific EffectCrosslinking:

Implementation Method 3

the adhesive is applied to the repair site. The solvent in the adhesive must then be allowed to evaporate. The repair patch is then applied to the repair site and pressed into place

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP4161765B1Repair patch for an elastomer component with an improved connection layer
Publication Date: 2024.04.10 REMA TIP TOP AG
  • EP4161765B1 patent drawingFigure 1
  • EP4161765B1 patent drawingFigure 2
  • EP4161765B1 patent drawingFigure 3

AI summary

The invention relates to an repair patch for an elastomer component, in particular for a vehicle tyre, the use thereof and a method for connecting a repair patch to an elastomer component. The repair patch (1) comprises a cover layer (10), a connection layer (30) for placing on a wall (80) of the elastomer component (40), and at least one intermediate layer (20) arranged between the connection layer (30) and the cover layer (10), wherein the connection layer (30) contains a first and a second natural rubber component before the vulcanisation with the elastomer component (40), wherein the first natural rubber component has a lower molecular weight Mw than the second natural rubber component, in such a way that a mixture of the first and the second natural rubber components has a bimodal molecular weight distribution.