Foam Abrasive Coating for Stronger Grain Retention at Edges

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Solution Overview

Problem

Existing foam abrasives face issues with abrasive grains detachment at edges during grinding, leading to premature wear and unwanted scratches, despite the base material still being usable, due to inadequate bonding with the base binder.

Innovation Solution

The use of a thermoplastic polyurethane base binder combined with a topcoat, such as a reactive or polyurethane-based two-component adhesive, enhances the bonding of abrasive grains to the foam base, providing mechanical and chemical stability under high stress conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a base binder is used to fix abrasive grains to the foam base, then the abrasive grains are bonded to the base material, but the abrasive grains detach at edges during grinding due to inadequate bonding strength

Engineering Contradiction:
Improvebonding strengthVSAvoidgrain retention
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent combines a base binder layer with a topcoat layer to create a composite bonding structure. The base binder (thermoplastic polyurethane or polyvinyl acetate) provides initial adhesion to the foam base, while the topcoat (reactive adhesive or polyurethane-based two-component adhesive) provides enhanced bonding strength and edge stability. This composite approach resolves the contradiction by integrating materials with complementary properties to achieve both initial bonding and sustained grain retention under grinding stress.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent changes the bonding parameters by introducing a two-layer binder system with different chemical and mechanical properties. The topcoat layer uses reactive adhesives or two-component polyurethane adhesives that cure to form crosslinked networks, significantly increasing bonding strength compared to the base binder alone. This parameter change in bonding chemistry and structure enables the abrasive grains to withstand edge stresses during grinding without detachment.

Inventive Principle:
Principle #35Parameter changes

2Duration of action of stationary object

If a topcoat is applied to cover abrasive grains, then grain detachment is prevented and service life is increased, but manufacturing complexity and process steps are increased

Engineering Contradiction:
Improveservice lifeVSAvoidmanufacturing process
Core Design Contradiction:
Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The patent applies the topcoat layer after the base binder has already fixed the abrasive grains to the foam base. This preliminary action of the base binder creates a stable foundation that holds grains in position, allowing the topcoat to be applied subsequently to enhance bonding without causing grain displacement. This sequential application resolves the manufacturing complexity by breaking the process into manageable stages rather than requiring a single complex coating step.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The bonding system is segmented into two functional layers: a base binder layer for initial grain fixation and a topcoat layer for enhanced bonding and protection. This segmentation allows each layer to be optimized for its specific function and applied using appropriate processes, reducing overall manufacturing complexity compared to using a single thick binder layer that would require more complex formulation and application control.

Inventive Principle:
Principle #1Segmentation

3Reliability

If abrasive grains are firmly bonded to prevent detachment, then service life increases, but the foam base material flexibility and elastic deformation are reduced

Engineering Contradiction:
Improvegrain retentionVSAvoidfoam flexibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent implements local quality by concentrating the strong bonding function in the topcoat layer that directly contacts the abrasive grains, while the base binder layer maintains flexibility by bonding to the foam base. This localized functional distribution allows the foam to elastically deform during grinding while the topcoat layer provides firm grain retention. The base binder uses softer materials (thermoplastic polyurethane or polyvinyl acetate) that accommodate foam flexibility, resolving the contradiction between firm bonding and foam adaptability.

Inventive Principle:
Principle #3Local quality

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 solution significantly increases the service life and material removal rate of foam abrasives while improving surface quality by preventing grain detachment and reducing scratches.

Implementation Method 1

abrasive grains fixed to at least one surface of the foam abrasive by means of a base binder made of thermoplastic polyurethane (TPU)

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 2

the abrasive grains be covered with a topcoat

Methodology Applied
Scientific EffectDeposition: Deposition (physical)

Data Source

PatentEP4065314B1Foam abrasive and method for producing same
Publication Date: 2026.01.07 ROBERT BOSCH GMBH
  • EP4065314B1 patent drawingFigure 1
  • EP4065314B1 patent drawingFigure 2

AI summary

The invention relates to a foam abrasive (10) for grinding a workpiece, comprising a main part (14) made of foam, in particular polyurethane foam, and abrasive grains (12) which are fixed to at least one surface (16) of the foam abrasive (10) by means of a base binder (18) made of thermoplastic polyurethane (TPU). According to the invention, the abrasive grains (12) are covered with a cover binder (20). The invention additionally relates to a method for producing the foam abrasive (10).