A complete guide to the application of PU sole release agent

# Preface

In the mass production process of PU / EVA / rubber / PVC soles, demoulding efficiency, surface quality, environmental compliance and cost control have always been the core issues that shoe material manufacturing companies are most concerned about. With the advantages of high safety, stable efficiency, and adaptability to automated production lines, water-based polyurethane release agents have become an important solution in the field of modern shoe material molding. This article focuses on highly diluted water-based PU release agents, systematically explaining product selection, construction technology, application skills and industry value, helping shoe material factories stabilize yield rates, improve production efficiency and reduce overall manufacturing costs.

# 1. The core role and industry value of PU sole release agent

PU soles are widely used in sports shoes, casual shoes and business shoes due to their lightweight, wear-resistant, excellent resilience and high-end texture.

However, polyurethane material itself has strong adhesion, and during high-temperature foaming or casting process, it is easy to cause:

• Sticky mold
• strain
• pinhole
• bubble
• Uneven gloss

These defects will directly increase the defective rate and production costs.

As an important isolation layer between the mold and the sole material, the release agent directly affects the molding stability and final surface effect.

The water-based polyurethane release agent recommended in this article is specially developed for a variety of shoe material molding processes and has:

• 5-30 times higher dilution ratio
• No VOCs
• Low odor, no irritation
• Quick drying
• Removal without residue

and other characteristics.

The product is compatible with PU, EVA, rubber and PVC soles, and is suitable for automatic spraying and manual construction methods. It is an industrial solution that takes into account quality, efficiency and environmental protection requirements.

# 2. Core product advantages of Water-based PU sole release agent

# The production value that shoe material factories focus on

# 1. High-gloss demoulding, more uniform surface texture

The high-gloss film-forming formula can form a uniform and dense isolation film on the mold surface, effectively preventing material adhesion and surface scratches.

accomplish:

• Sole texture is clearer
• Surface gloss is more uniform
• Greater consistency in appearance

Some products can even meet shipping standards without secondary polishing, thus improving product quality and market competitiveness.

# 2. Reduce the defect rate and stabilize the production yield rate

Special emulsification technology makes the release film layer thinner and more uniform, which can effectively reduce:

• pinhole
• bubble
• Flow marks
• pitting

and other frequently asked questions.

Even when faced with complex textures or deep-cavity molds, it can maintain smooth demoulding, significantly reducing rework rates and raw material waste.

# 3. No residue, does not affect subsequent processing procedures

After demoulding, no oil, white powder or migration will remain on the surface of the mold and sole.

Therefore, it will not affect the following:

• viscose
• print
• Spray

and other processing techniques.

The product has higher consistency and is especially suitable for continuous and mass production.

# 4. High dilution ratio, lower overall cost of use

The original solution can usually be diluted with water at a ratio of 5-35 times.

Each kilogram of product can cover about 20 square meters of mold area, effectively reducing material consumption and additive costs per unit sole.

For large-scale shoe material production lines, it has very obvious cost advantages.

# 5. Fast drying and improved production cycle time

Drying can be completed in as little as 3 minutes, making it suitable for high-speed automated production lines.

Advantages include:

• Shorten mold waiting time
• Increase productivity per hour
• Ease order delivery pressure

# 6. Environmentally friendly and safe, in line with the trend of green manufacturing

The product is VOC-free, has low odor and is easily biodegradable.

Can help companies:

• Improve workshop working environment
• Improve employee safety
• Meet EU REACH and shoe material environmental regulations requirements

At the same time, it helps to pass export audits and social responsibility factory inspections.

# 7. Protect the mold and extend the service life of the mold

The product has both anti-corrosion and anti-rust properties, which can reduce:

• Mold oxidation
• dirt accumulation
• mechanical wear

This reduces mold maintenance frequency and replacement costs, and improves overall equipment utilization.

# 8. Compatible with multiple materials, reducing factory stocking pressure

Applies to:

• PU sole
• EVA sole
• Rubber sole
• PVC sole

One release agent can cover a variety of shoe material molding scenarios, helping factories reduce product variety and inventory pressure.

# 9. Stable storage, suitable for automatic spraying systems

The product is not easy to stratify or precipitate during long-term storage, and has excellent stability.

It can be directly connected to automatic spraying equipment, which can provide a more stable and consistent coating effect compared to manual construction, and is more suitable for standardized production management.

# 3. Standard construction process of PU sole release agent

# Shoe Material Factory Practical Guide

# 1. Mold pretreatment

Thoroughly clean the oil, residual glue, dust and other impurities on the mold surface.

Make sure the mold is completely dry before construction. For old molds, it is recommended to perform deep cleaning first to ensure that the release agent forms a uniform film.

# 2. Dilution ratio

It is recommended to use clean water to dilute 5-35 times, with deionized water preferred.

The dilution ratio should be based on:

• Mold temperature
• Product structure complexity
• Production line speed

Make adjustments.

General advice:

• Shallow mold/high temperature mold: use higher dilution ratio
• Deep cavity/complex texture molds: use lower dilution ratio

# 3. Coating method

# automatic spraying

Suitable for automated assembly lines to achieve:

• Even atomization
• Thinner film
• Construction efficiency is higher

# Hand brushing or wiping

Applies to:

• small batch production
• Sample proofing
• partial repair

Core requirements for construction: thin and even, no leakage or accumulation.

# 4. Drying and film formation

After it is fully dried at normal temperature or the residual temperature of the mold, the mold can be closed and poured.

Failure to dry completely may result in:

• bubble
• watermark
• adhesions

etc. questions.

# 5. Continuous production maintenance

During the continuous production process, the release agent should be reapplied regularly according to the production rhythm.

At the same time, it is recommended to clean the mold regularly to avoid long-term fouling that affects the surface effect and demolding stability.

# 4. Frequently Asked Questions (FAQ)

# Q1: Why is water-based release agent preferred over solvent-based products?

Water-based release agents use water as the dispersion medium and have:

• No VOCs
• Not flammable
• low odor
• Safer and more environmentally friendly

and other advantages.

At the same time, its residue-free properties will not affect subsequent processing techniques, and is more in line with the current environmentally friendly upgrade trend in the shoe material industry.

# Q2: How to determine the optimal dilution ratio?

It is recommended to conduct trial production first with a ratio of 1:10-1:20.

observe:

• Is demoulding smooth?
• Is the surface gloss uniform?
• Are there pinholes or defects?

On the premise of ensuring the demoulding effect, gradually increase the dilution ratio to achieve the lowest cost of use.

# Q3: Will it affect the adhesive strength of the soles?

Won’t.

The product will not produce any migration residue after normal use, nor will it damage the bonding interface.

At present, it has passed the verification of the back-end viscose process of most shoe factories.

# Q4: Is it suitable for high temperature or low temperature molds?

Applicable.

The product has good heat resistance and stability and can be adapted to the common shoe material molding temperature range.

It can still maintain stable performance of fast drying, non-decomposition and non-stickiness under high temperature conditions.

# 5. Summary

Water-based polyurethane release agent is not only a release aid in shoe material molding, but also an important production solution to improve efficiency, stabilize quality and meet environmental protection requirements.

From reducing defect rates and improving surface gloss, to reducing costs through high dilution ratios, to meeting VOC environmental regulations, protecting molds and being compatible with a variety of shoe materials, it can comprehensively solve key issues in shoe factory production.

By following:

Mold cleaning -> Precise dilution -> Uniform coating -> Full drying

This standard process can maximize the performance of the release agent and achieve:

• Stable mass production
• Reduce operating costs
• Improve product quality

If you need to test product suitability, you can provide sole material and process parameters, We can provide you with exclusive dilution solutions and sample testing suggestions, to help each pair of soles achieve efficient, bright, and environmentally friendly demoulding.