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Complete Analysis of Resin Processing Lubricants: Principles, Models, and Application Guide

TES Additives and Resins 2026-06-25 14:35:21

Introduction: The "Golden Duo" of Plastic Processing

In plastic processing, lubricants are indispensable key additives. Acting like a “lubricant” for plastic melts, they effectively reduce frictional resistance between molecules and between the material and equipment, improve melt flowability, and enhance processing efficiency and product quality. Statistics show that the proper use of lubricants can increase production efficiency by 15–30% and reduce energy consumption by 10–20%.

More than 90% of plastic processing requires lubricants.
Two major categories: internal lubrication / external lubrication
6+ Main Application Resins
5 Main Types of Lubricants

1. Working Principle of Lubricants

1.1 Basic Concepts

Resin processing lubricants are a type of additive that can improve the flow properties of plastic melts. Their molecular structure typically consists of a non-polar long chain and a polar group, functioning by forming a lubrication layer between polymer molecular chains or between the polymer and the metal surface of processing equipment.

The core function of lubricants.

✅ Reduce melt viscosity and improve flowability

✅ Promote melting, shorten plasticization time

Facilitates demolding and reduces equipment adhesion.

✅ Prevent static electricity, reduce dust adhesion

✅ Improve product surface glossiness

Reduce energy consumption and improve production efficiency

1.2 Mechanism of Action of Internal and External Lubrication

Internal Lubricant
Mechanism of action: Internal lubricants have good compatibility with polymers and can penetrate between polymer molecular chains, reducing internal friction between the chains and enabling the chain segments to slide relative to each other more easily.

Characteristics of internal lubricants:

Good compatibility

with good affinity to the resin molecular chains

Reduce internal friction

Reduce internal friction resistance of the melt.

Reduce melt viscosity

Improve melting rate

Promote plasticization

Improve plasticizing performance and increase processing efficiency.

External Lubricant
Mechanism of action: External lubricants have poor compatibility with polymers and migrate to the surface of the melt, forming a lubricating film between the polymer and the metal surfaces of processing equipment.

Characteristics of external lubricants:

Poor compatibility

Easy to migrate from the interior of the melt to the outside.

Interfacial lubrication

Form an isolation film between the melt and the mold.

For easy demolding

Prevent adhesion to the surface of the barrel or mold.

Adjust the plasticizing point

Delay or advance the material plasticizing time.

1.3 Balance Between Internal and External Lubrication

Most lubricants serve both internal and external lubrication functions, but some are more oriented toward internal lubrication, while others are more oriented toward external lubrication. The same lubricant may exhibit different lubricating effects in different resins or under different processing conditions.

Judgment basis	Internal lubricant	External lubricant
Compatibility
Polar groups	High polarity	Low polarity
Migration Direction	Into the molten body	Toward the melt surface
Main function	Reduce internal friction	Interface Isolation

2. Main Types of Lubricants

2.1 Hydrocarbon Lubricants

🟡 Polyethylene Wax (PE Wax)
Model examples: OPE wax (Oxidized Polyethylene Wax), ordinary polyethylene wax.
Melting point range: 100-120°C


Ordinary PE wax	Primarily external lubrication, with good migratory properties.	PVC external lubricant, color masterbatch dispersant
Oxidized PE wax	Dual internal and external lubrication, enhanced polarity.	PVC, PU, ABS, etc.
High molecular weight PE wax	Good lubricity in the middle and later stages, anti-sticking.	Profile and pipe processing

Yellow Polypropylene Wax (PP Wax)
Features: good compatibility with PP resin, suitable for polyolefin processing
Applications: PP, PE films, pipes, injection molded parts

🟡 Paraffin Waxes


Liquid paraffin	<40°C	Primarily for internal lubrication, with fast evaporation.	PVC soft products
Solid paraffin	50-70°C	External lubrication, good surface gloss	PVC rigid products, PE, PP
Microcrystalline wax	65-90°C	Good thermal stability, better lubricity than paraffin.	High-end plastic products

2.2 Fatty Acids and Their Derivatives

Stearic Acid
Chemical formula: CH₃(CH₂)₁₆COOH
Melting point: 69-71°C
Dual functionality: acts as an internal lubricant at low temperatures and as an external lubricant at high temperatures.

Fatty acid metal soaps


Calcium stearate	150-160°C	Provides both internal and external lubrication and stabilizing effects.	PVC heat stabilizers, lubricants
Zinc stearate	120-125°C	Internal lubrication, non-toxic	Food-grade PVC, pharmaceutical packaging
Lead stearate	105-110°C	External lubrication, excellent extreme pressure performance.	Wires and cables, rigid PVC
Barium stearate	130-140°C	Good lubricity and thermal stability.	PVC pipes and profiles

2.3 Fatty Acid Amides


Oleamide	72-76°C	Internal lubrication, anti-static, and lubricity	0.1-0.5%	PE、PP、PA、PVC
Erucamide	80-85°C	Long-lasting smoothness, stable at high temperatures	0.1-0.5%	High-end films, multilayer co-extrusion
Stearamide	98-105°C	External lubrication, good transparency	0.1-2.0%	PVC, PS, UF resin
EBS (Ethylene Bis Stearamide)	140-145°C	Internal/external lubrication, anti-sticking, dispersion	0.2-2.0%	PE、PP、PS、ABS

2.4 Ester Lubricants

🟢 Glyceryl Monostearate (GMS)
Structure: glycerol + 1 molecule of stearic acid
Characteristics: Combines internal and external lubrication effects, good transparency.
Applications: PVC, ABS, food packaging materials
Dosage: 0.3–2.0%

Butyl stearate
Characteristics: Significant internal lubrication effect, good transparency.
Application: PVC transparent sheet, injection molding, calendering
Dosage: 0.5-1.5%

Glyceryl trihydroxystearate
Applications: PVC, ABS, MBS lubricants, synthetic rubber release agents
Usage: 0.25–1.5%

2.5 Special Function Lubricants

	Representative products
Processing additives	ACR (Acrylic Copolymer)	Promotes plasticization and the “molecular bearing” effect.	PVC extrusion, injection molding
Composite lubricant	Calcium-zinc stabilizer + lubricant system	Stabilizing + Lubricating Composite Function	Eco-friendly PVC products
Polymer lubricant	Polyvinylpyrrolidone class	Long-lasting lubrication, good compatibility	Engineering plastics

3. Key Performance Indicators

		Detection Method	Reference range
	Temperature at which the lubricant begins to flow	ASTM D127	60-150°C
	Free fatty acid content	ASTM D664	0-30 mgKOH/g
	Unsaturation degree	ASTM D1959	0-90 gI₂/100g
	Melting state fluidity	ASTM D445	10-500 mm²/s
Thermogravimetric analysis	High-temperature stability	Thermogravimetric analysis (TGA)	<1% (200°C, 1h)

IV. Detailed Explanation of Application Areas

4.1 PVC Resin Processing

PVC is the resin type that uses the largest amount of lubricants, accounting for more than 60% of the total lubricant consumption in plastics.

Key Points for the Design of PVC Processing Lubrication Systems

Balance between internal and external factors

Adjust the internal/external lubrication ratio according to the processing equipment and product requirements.

Thermal stability matching

Synergistically with the heat stabilizer to avoid mutual interference

Plasticization control

Adjust the plasticization rate and degree of plasticization by using lubricants.

Transparency considerations

For transparent products, choose lubricants with good transparency.

Types of PVC Products	Main lubricant	Dosage range	Functional characteristics
	OPE wax + stearic acid + calcium stearate	1.0-2.5%	Primarily external lubrication, while also taking internal lubrication into account.
	PE wax + paraffin wax + butyl stearate	1.5-3.0%	Balanced lubrication system
Transparent sheet material	Butyl stearate + GMS + OPE wax	0.8-1.5%	Primarily internal lubrication, high transparency
cable material	Lead stearate + PE wax + paraffin wax	2.0-4.0%	Mainly externally lubricated, with good extreme pressure properties
Soft products	Liquid paraffin + stearic acid	0.5-1.5%	Primarily internally lubricated

4.2 Polyolefin (PE/PP) Processing

🟦 Polyethylene (PE)

PE type	Main Lubricant
LDPE	Oleamide, Erucamide	0.1-0.5%	Film antiblock agent, slip agent
LLDPE	Oleamide, EBS	0.2-0.8%	Thin film, tubing
HDPE	EBS, PE wax	0.3-1.0%	Hollow containers, injection-molded parts
PE wood-plastic composite	OPE wax, zinc stearate	1.0-3.0%	Wood-plastic profiles

Polypropylene (PP)
Common lubricants: Oleamide, EBS, PP wax
Special application: BOPP film requires the selection of high-purity erucamide (opening agent + slip agent).

4.3 Engineering Plastics

Engineering plastics	Recommend lubricant		Precautions
ABS	EBS, zinc stearate, GMS	0.5-2.0%	Pay attention to compatibility.
PS	EBS, paraffin	0.3-1.5%	Use with caution on transparent products.
PA	Oleamide, EBS	0.5-2.0%	High-temperature processing use
PC	Silicone lubricant, PTFE wax	0.5-1.5%	High-temperature stable type
POM	Polyethylene wax, EBS	0.3-1.0%	Low friction level
PET/PBT	Zinc stearate, EBS	0.5-1.5%	Hydrolytic stability

4.4 Other Application Areas

Color masterbatch processing
Main lubricants: PE wax, EBS
Function: Pigment dispersant, anti-sticking mold agent
Dosage: 2–5%

🔹 Wood-Plastic Composites (WPC)
Main lubricants: OPE wax, calcium/zinc stearate composite system
Dosage: 1.0-3.0%
Feature: Requires simultaneous lubrication of wood powder and plastic components.

Rubber Processing
Main lubricants: stearic acid, paraffin wax, PE wax
Function: Release agent, processing aid

V. Comparative Analysis of Advantages and Disadvantages

5.1 Comprehensive Comparison of Various Lubricants Translate the above content into English and output only the translation result, with no explanation.

		Lubrication effect	Thermal stability	Compatibility	Transparency	Environmental friendliness

PE wax
Stearic acid
Metal soap						View Type
Oleamide
Erucamide
EBS
GMS

5.2 Advantages and Disadvantages of Internal/External Lubricants

			Applicable Scenarios
Internal lubricant	Reduce melt viscosity Promote plasticization Improve product toughness Improve transparency	Excessive amounts may precipitate. Possible reduction of heat distortion temperature High compatibility requirements	High-viscosity resin Transparent products Need to promote plasticization.
External lubricant	Easy demolding Protect the mold. Improve surface gloss Adjust plasticizing point	Excessive amounts affect plasticization. May reduce mechanical properties. May affect welding strength	Difficult-to-demold products High-gloss products Delayed plasticization is required.

VI. Selection Guide and Precautions

6.1 Selection Procedure

6-Step Method for Selecting Lubricants

Clearly identify the resin type:
PVC/PE/PP/ABS/Engineering Plastics

Determine the processing technology:
Extrusion / Injection Molding / Calendering / Blow Molding

Analyze product requirements:
Transparency / Mechanical Properties / Surface Quality

Select lubrication type:
Internal lubrication / external lubrication / composite system

Matching performance indicators:
Melting Point / Acid Value / Thermal Stability

Pilot-scale validation and optimization:
Determine the optimal formulation and dosage.

6.2 Common Problem Solutions

	Root Cause Analysis	Solution
Poor plasticization	Excessive external lubricant	Reduce external lubricants and increase internal lubricants.
Product sticking to mold	Insufficient external lubricant	Increase the amount of paraffin wax or PE wax.
Surface fogging	Lubricant exudation	Choose a lubricant with better compatibility.
Melt rupture	Insufficient or excessive lubrication	Adjust the balance between internal and external lubrication.
Mechanical performance degradation	Excess lubricant	Reduce total usage and optimize the ratio.
Poor transparency	Poor lubricant compatibility	Select an internal lubricant with good transparency.

6.3 Formula Balancing Principles

⚖️ Key Points for Balancing Internal and External Lubrication

Plasticization degree control:
Adjust the material plasticization rate by varying the ratio of internal and external lubricants.

Torque balance:
Maintain a stable machining torque

Extraction Control:
Ensure the lubricant dosage is within the allowable range of compatibility.

Synergistic effect:
The effect of using multiple lubricants in combination is better.

Stabilizer formulation:
Synergistic with heat stabilizers, without producing any negative effects

6.4 Dosage Reference

Lubricant Types	General dosage range	Excessive performance
	0.3-1.0%	Precipitation, fogging, poor plasticization
PE wax	0.5-2.0%	Decreased mechanical performance, precipitation
Stearic acid	0.3-1.0%	Frosting, decreased thermal stability
metal soap	0.5-2.0%	Precipitation, decreased transparency
Oleamide	0.1-0.5%	High cost, slight precipitation
EBS	0.2-2.0%	Poor dispersion, affecting color matching

VII. Future Development Trends

7.1 Trend Toward Environmental Protection

With increasingly strict environmental regulations, plastic lubricants are developing towards non-toxic, low volatile, and biodegradable directions.

Traditional products	Environmental alternative products
Lead salt stabilizer system	Calcium-zinc stabilizer + composite lubricant	Non-toxic, environmentally friendly
Paraffin (petroleum-based)	Plant wax, carnauba wax	Renewable, bio-based
Halogenated lubricants	Halogen-free flame-retardant lubricant	Low smoke, halogen-free

7.2 Functionalization Trends

🚀 New Type of Functional Lubricant

Multifunctional composite lubricant:
Lubrication + Stability + Antioxidant Composite Function

Nano Lubricant:
Nanomaterial-enhanced lubrication performance

Self-healing lubricant:
Maintain lubrication effect continuously during processing.

Smart-responsive lubricants:
Automatically adjust lubrication performance according to processing conditions

7.3 Trends in High Performance

High-temperature lubricants:
Suitable for high-temperature processing of engineering plastics (>300°C)
Low-friction lubricant:
For self-lubricating products
Long-life lubricant:
For maintenance-free products
Compatibility-adjustable lubricant:
Adjust compatibility according to formulation requirements.

7.4 Market Development Forecast

According to data from market research institutions, the global plastic lubricants market is expected to continue growing at an annual rate of 5–6%, in which:

Asia-Pacific Region:
The fastest-growing markets, with China and India as the main drivers.
Engineering plastics sector:
The fastest-growing application area
Environmentally friendly products:
Faster growth than traditional products

📝 Conclusion

As an important additive in plastics processing, resin processing lubricants directly affect product quality and production efficiency through their selection and application. Mastering the working principles, types, characteristics, and application techniques of lubricants is an essential skill for every plastics processing engineer.

💡 Key Points Recap

Internal lubrication:
Reduce internal friction in the melt and promote plasticization.
External lubrication:
Interface isolation for easy demolding.
Balance is key:
Adjust the ratio of internal and external lubricants according to product requirements.
Compatibility is fundamental.
Choose a lubricant with moderate compatibility with resin.
Environmental protection is the trend.
Develop toward being non-toxic and biodegradable.

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Complete Analysis of Resin Processing Lubricants: Principles, Models, and Application Guide

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