Rustproof Threaded Coating for Stable Friction Under Repeated Tightening

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Solution Overview

Problem

Existing methods for producing rust-proofed threaded parts, such as bolts and nuts, face issues with increased friction coefficient during repeated tightening, require multiple coating treatments, and often use organic solvents necessitating explosion-proof facilities and high-temperature drying.

Innovation Solution

A single coating treatment using a rust proofing treatment liquid with a binder resin containing silica and modified epoxy or acrylic resins, obtained through graft polymerization with carboxylic acid-containing acrylic polymers, disperses rust inhibitors and lubricants in a water-soluble resin to stabilize the friction coefficient without organic solvents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a zinc plating layer is formed on the iron substrate to provide rustproof performance, then corrosion resistance is improved, but the friction coefficient gradually increases when tightening is repeated

Engineering Contradiction:

Improverustproof performanceVSAvoidfriction coefficient

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent combines the rust inhibitor layer and friction coefficient stabilizing layer into a single integrated coating layer. This coating layer contains both rust inhibitors (such as phosphates or chromates) and friction modifiers (such as wax or PTFE particles) dispersed in a binder, allowing simultaneous achievement of corrosion protection and stable friction characteristics through one coating process

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The coating layer is formulated as a composite material system comprising multiple functional components: rust inhibitors for corrosion protection, friction modifiers for stable friction coefficient, binders for adhesion, and solvents for application. This composite structure enables the coating to simultaneously deliver both rustproof performance and friction stability

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If a rust inhibitor layer and friction coefficient stabilizing layer are formed separately to solve the friction increase problem, then friction coefficient stability is improved, but manufacturing cost increases due to multiple coating treatments

Engineering Contradiction:

Improvefriction coefficientVSAvoidmanufacturing cost

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The patent merges the formation of rust inhibitor layer and friction coefficient stabilizing layer into a single coating operation. The coating composition contains both rust inhibitors and friction modifiers that are applied simultaneously in one step, eliminating the need for separate coating processes and reducing manufacturing complexity and cost

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If acrylic resin is used as film forming component for both rust inhibitor layer and friction coefficient stabilizing layer, then coating performance is achieved, but explosion-proof facilities are required due to use of solvent with low flash point

Engineering Contradiction:

Improvecoating performanceVSAvoidexplosion hazard

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the solvent parameter from organic solvent with low flash point to water as the base solvent. This parameter change raises the flash point significantly, eliminating explosion hazards while maintaining coating performance through careful formulation of the water-based coating composition including binders, rust inhibitors, and friction modifiers

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

This approach allows for a single coating treatment that stabilizes the friction coefficient during repeated tightening, eliminates the need for organic solvents, and enhances corrosion resistance, reducing costs and operational complexities.

Implementation Method 1

a binder resin containing silica and at least one of a modified epoxy resin obtained by graft polymerization using a carboxylic acid-containing acrylic polymer as a side chain and a modified acrylic resin obtained by graft polymerization using a carboxylic acid-containing acrylic polymer as a side chain

Methodology Applied

Scientific EffectGraft polymerization:

Data Source

PatentEP3461930B1Method for producing a rust-proofed threaded part, and rust-proofed threaded part

Publication Date: 2021.06.09 AOYAMA SEISAKUSHO CO LTD

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AI summary

Threaded parts such as bolts are rust-proofed by using a treatment liquid comprising a binder resin containing silica and at least one of a modified epoxy resin obtained by graft polymerization using a carboxylic acid-containing acrylic polymer as a side chain and a modified acrylic resin obtained by graft polymerization using a carboxylic acid-containing acrylic polymer as a side chain. By using this treatment liquid, coating treatment can be carried out at one time without need to use an organic solvent. There is an advantage that the friction coefficient does not increase even when tightening is repeated.