Phenolic Resin Purification Solution

Chapter 1: Background and Requirements

1.1 Introduction to Phenolic Resin

Phenolic Resin, scientifically known as phenol-formaldehyde resin, is one of the earliest industrialized synthetic resins in the world, formed by polycondensation of phenolic compounds and formaldehyde under catalyst action. Due to its excellent heat resistance, flame retardancy, mechanical strength and electrical insulation, it is widely used in:

• Electronic materials：Photoresist Resin、PCB Substrate、Semiconductor Encapsulation

• Composite Materials: Glass fiber reinforced materials, friction materials (brake pads)

• Coatings and Adhesives: High-temperature resistant coatings, wood adhesives

• Refractory Materials: Fire bricks, insulation materials

• Engineering Plastics: Electrical switches, automotive components

1.2 Market Demand for High-Purity Phenolic Resin

With the rapid development of the electronic information industry and new energy materials, higher purity requirements have been placed on phenolic resins:

Application Field	Purity Requirement	Key Impurity Limits	Market Price (10k CNY/ton)
Photoresist Resin	≥99.5%	Free Phenol<500ppm Ash Content<50ppm	6-12
Semiconductor Encapsulation	≥99.0%	Metal Ions<10ppm Chlorine Ions<20ppm	4-8
PCB Substrate	≥98.5%	Free Phenol<1000ppm Moisture<1%	2-5
General Industrial Grade	≥95%	Free Phenol<3000ppm	1-2

1.3 Domestic Production Opportunities

Currently, the import dependence of high-end phenolic resins (photoresist grade, semiconductor grade) reaches 60-80%, with huge domestic substitution space. Domestic production has the following advantages:

• Cost Advantage: Local production costs 30-50% lower than imports

• Delivery Advantage: No need for long-term international logistics, delivery within 1 week

• Service Advantage: Localized technical support, rapid response to customer needs

• Supply Chain Security: Avoid supply disruption risks from international trade friction

Chapter 2: Purity Requirements and Challenges for Phenolic Resin

2.1 Core Quality Indicators

High-purity phenolic resin needs to meet the following key indicators:

Item	Photoresist Grade	Semiconductor packaging level	PCB Grade
Molecular weight（Mw）	3,000-8,000	5,000-12,000	8,000-20,000
PolydispersityPDI	1.3-1.8	1.5-2.0	1.8-2.5
Softening point(℃)	90-130	100-140	110-150
Hydroxyl content(%)	15-25	12-20	10-18
Free Phenol(ppm)	<500	<1,000	❤️<3,000
Free formaldehyde(ppm)	<200	<500	<1,000
Ash Content(ppm)	<50	<100	<300
Metal Ions(ppb)	<10	<20	<50
Chlorine Ions(ppm)	<20	<50	<100
Color(Gardner)	❤️<3	<4	<5
Moisture(%)	<0.5	<1.0	<2.0

 

2.2 Main Challenges in Purification

• Free Phenol and Free Formaldehyde Removal - Unreacted monomer residues affect resin performance and safety
• Oligomer and Polymer Separation - Molecular weight distribution (PDI) requires strict control
• Metal Ion Contamination - Catalyst residues (such as oxalic acid, hydrochloric acid, etc.) and equipment corrosion introduction
• Heat Sensitivity - Easy to further polymerize or degrade at high temperatures, color deepening
• High Viscosity - Solid or high-viscosity liquid at room temperature, difficult for traditional distillation

Chapter 3: Traditional Purification Methods and Their Limitations

3.1 Method 1: Water Washing + Neutralization

【Process Flow】 Resin Solution → Hot Water Washing → Alkali Neutralization → Standing Layering → Dehydration

Advantages	limitation
✓Low cost, simple operation	✗Free phenol removal rate < 60%
✓Can remove some water-soluble impurities	✗Poor removal of metal ions
✓Suitable for industrial-grade products	✗Generates a large amount of wastewater (significant environmental pressure)

3.2 Method 2: Solvent Extraction

【Process Flow】 Resin Dissolved in Organic Solvent → Adding Poor Solvent Precipitation → Filtration → Vacuum Drying

Advantages	Limitations
✓ Can remove low molecular weight components	✗ High solvent consumption (5-10 times the resin mass)
✓ Allows for some degree of PDI adjustment	✗ High solvent recovery costs
✓ Suitable for small-batch, high-end products	✗ Low yield (70-85%)

3.3 Method 3: Conventional Vacuum Distillation

【Process Flow】 Resin Melting → Reduced Pressure Distillation (0.1-1 kPa) → Collecting Fractions

Advantages	Limitations:
✓ Effectively removes free phenols and formaldehyde	✗ Requires high temperatures (180-250℃), leading to easy polymerization/degradation of the resin.
✓ No solvent residue	✗ Long residence time (2-6 hours), resulting in color darkening.
✓ Recyclable monomers	✗ High viscosity, leading to low mass transfer efficiency.

3.4 Comparison Summary of Traditional Methods

 

 

Methods:	Free phenol removal rate	PDI control	Yield	Color	Cost	Applicable Grades:
Water washing + neutralization	50-60%	✗	90-95%	Deterioration	Low	Industrial Grade
Solvent extraction	70-85%	✓	70-85%	Improvement	High	Electronic Grade
Conventional vacuum distillation	80-90%	✗	75-88%	Severe Deterioration	Medium	PCB Grade
Short-path molecular distillation	95-99%	✓ Precise	88-95%	Excellent	Medium	Photoresist Grade

Obviously, traditional methods have significant shortcomings in high purity, low color, and precise molecular weight control, unable to meet the requirements of photoresist-grade and semiconductor encapsulation-grade phenolic resins.

Chapter 4: Yuanhuai Solution

4.1 Core Technology: Short Path Molecular Distillation

Yuanhuai YHCHEM Molecular Distillation System is a special liquid-liquid separation technology that achieves separation under high vacuum and low temperature conditions by utilizing differences in the mean free path of different substance molecules, particularly suitable for purification of heat-sensitive, high-viscosity, and high-boiling-point materials.

4.2 Working Principle

 

 

Steps:	Process Description	Key Parameters
① Material feeding	The preheated resin solution enters the evaporator.	Fluidity: Good
② Film formation	A scraper spreads the material into a thin film.	Rotation Speed: 10-300 rpm
③ Heating	The heating surface is maintained at a relatively low temperature.	Pressure: Much lower than conventional distillation
④ Evaporation	Light components (low boiling point) evaporate and escape.	Mean Free Path: >2-5 cm
⑤ Short-distance transport	The evaporated molecules travel in a straight line to the condensing surface.	Distance: 2-5 cm, no collisions
⑥ Condensation	The light components condense on the condensing surface.	Temperature: -10~20℃
⑦ Separation	The heavy components flow down along the heating surface.	Unvaporized High Molecular Weight Substances
⑧ Collection	The light and heavy components are collected separately.	Continuous segmented operation

4.3 Unique Advantages for Phenolic Resin Purification

Technical Features:	Significance for phenolic resins:
Ultra-high vacuum	Boiling point reduced by 80-150℃, preventing thermal polymerization/degradation
Extremely short residence time	2-30 seconds, no color degradation, maintaining transparent light yellow color
Low-temperature operation	80-180℃, protecting heat-sensitive hydroxyl groups and ether bonds
Continuous segmented collection	Precise separation of oligomers, medium polymers, and high polymers, controlling PDI
Wiped-film design	Uniform film formation of high-viscosity resins, high mass transfer efficiency
All material contact surfaces made of 316L stainless steel	Eliminates metal ion contamination

Chapter 5: Core Process Equipment

(1) Core Distillation Unit

Components	Specifications/Materials	Features:
Evaporation area	0.1-10 m²	Customizable, with processing capacity of 5-500 kg/h
Scraper	PTFE/316L	Rotation speed of 10-300 rpm, forming a 0.1-1 mm thin film
Heating method	Thermal oil/Electric heating	Temperature control accuracy of ±2℃
Condenser	316L stainless steel	Built-in spiral tube, -10 to 20℃
Material	All 316L stainless steel + PTFE seal	Corrosion-resistant, low metal ion contamination

(2) Vacuum System

• Roots Pump + Rotary Vane Pump Combination: Ultimate vacuum 0.1 Pa

• Vacuum Gauge: Capacitance diaphragm vacuum gauge, accuracy 0.1 Pa

• Cold Trap: -80°C, protecting vacuum pump, recovering monomers

(3) Automation Control System

• PLC + Touch Screen: Siemens/Mitsubishi

• Real-time monitoring: temperature, vacuum level, feed rate, rotation speed

• Data Recording: Historical curves, batch traceability

• Alarm Protection: Over-temperature, vacuum abnormality, liquid level abnormality automatic shutdown

 

 

 

 

 

 

Chapter 6: Process Flow and Parameters

6.1 Complete Process Flow

6.2 Key Process Parameters

First Stage Distillation (Remove Light Components)

 

 

Parameters:	Set values:	Objective:
Feed temperature	60-80℃	To reduce viscosity for easier transportation
Evaporation temperature	120-150℃	To vaporize free phenol (boiling point 181℃)
Vacuum level	1-5 Pa	To lower the boiling point to 80-120℃
Wiper speed	150-250 rpm	To form a uniform thin film
Feed rate	10-30 kg/h·m²	Residence time: 5-15 seconds
Collected components	Light components (free phenol, formaldehyde, water)	5-15%

Effect: Free phenol reduced from 3000-8000 ppm to <500 ppm

Second Stage Distillation (Adjust Molecular Weight Distribution)

Parameters:	Settings:	Objective:
Evaporation temperature	150-170℃	Vaporization of oligomers (Mw < 2000)
Vacuum level	0.5-2 Pa	Lower boiling point
Wiper speed	100-200 rpm	Balanced mass transfer and residence time
Feed rate	8-20 kg/h·m²	Residence time: 10-30 seconds
Collected components	Light components (oligomers)	10-20%

Effect: PDI narrowed from 2.5-3.5 to 1.5-2.0

Third Stage Distillation (Refining)

Parameters:	Settings:	Purpose:
Evaporation temperature	170-180℃	Removal of catalysts and pigments
Vacuum level	0.1-1 Pa	Extreme vacuum
Wiper speed	80-150 rpm	Fine separation
Feed rate	5-15 kg/h·m²	Thorough contact
Collected components	Intermediate distillate (target product)	70-85%

Effect: Purity >99.0%, metal ions (combined with ion exchange) <10 ppb

6.3 Material Balance Example

Example based on 100 kg crude resin:

Process Stages	Material Type	Mass (kg)	Proportion of raw materials used	Material Disposition
Feeding	Crude Phenolic Resin	100	100%	Raw materials
Pre-treatment	Solvent Loss, Filtration Residue	2-3	2-3%	Solvents are recyclable
First Distillation	Light Components (Free Phenol, Formaldehyde, etc.)	8-12	8-12%	Can be resourcefully utilized
Second Distillation	Light Components (Oligomers)	10-15	10-15%	Partially reusable
Third Distillation	Heavy Components (Polymers, Impurities)	3-5	3-5%	Discarded or downgraded for other uses
Output	High-Purity Phenolic Resin	70-80	70-80%	Electronic grade/photolithography grade products

 

【Total Yield】70-80% 【Purity Enhancement】95% → 99%+

Chapter 7: Key Technical Advantages

7.1 Comparison with Traditional Methods

Indicators:	Traditional Vacuum Distillation	Solvent extraction	YHChem Molecular Distillation
Operating temperature	180-250℃	Room temperature - 60℃	80-180℃
Residence time	2-6 hours	Several hours	10-60 seconds
Vacuum level	0.1-1 kPa	Atmospheric pressure	0.1-10 Pa
Free phenol removal rate	80-90%	70-85%	95-99%
PDI control	✗	✓	Precise
Color change	Degradation: 3-5 levels	Improved by 1-2 levels	No degradation
Yield	75-88%	70-85%	88-95%
Solvent consumption	None	5-10 times	None
Energy consumption (kWh/ton)	800-1200	300-500 (including recovery)	400-600
Equipment fouling	Severe	None	Slight
Metal ion control	Moderate	Poor	Excellent (All 316L)
Continuous production	Difficult	Difficult	Supported

7.2 Core Advantages Summary

✓ Ultra-high Purity - Free phenol <500 ppm, free formaldehyde <200 ppm, meeting photoresist-grade requirements

✓ Precise Molecular Weight Control - PDI adjustable to 1.3-1.8, adaptable to different applications

✓ Color Retention - Light yellow transparent, no thermal degradation

✓ High Yield - 88-95%, 10-20% higher than solvent extraction

✓ Environmentally Friendly Zero Emission - No wastewater, no waste solvent, compliant with environmental policies

✓ Continuous Production - High degree of automation, low labor costs

✓ Long Equipment Life - 316L stainless steel, corrosion resistant, easy to clean

Chapter 8: Application Cases and Performance Indicators

Photoresist-Grade Phenolic Resin Purification

Customer: An electronic chemicals company (Pearl River Delta region)

Raw Material: Industrial-grade phenolic resin (95% purity, 5000 ppm free phenol)

Target: Photoresist grade (purity ≥99.5%, free phenol <500 ppm, PDI 1.5-1.8)

Process Parameters:

• Equipment: YMD-150

• Three-stage distillation, temperatures 120/150/170℃

• Vacuum level: 5/2/0.5 Pa

• Total processing time: Approximately 40 seconds

【Purification Effect Comparison】

Specifications	raw material	After one distillation	After two stages of distillation	Finished product	Target
Purity (%)	95.0	97.5	98.8	99.6	≥99.5
Free Phenol (ppm)	5000	800	350	<200	<500
Free Formaldehyde (ppm)	800	200	80	<100	<200
PDI	2.8	2.6	1.9	1.6	1.5-1.8
Softening Point (°C)	105	108	112	115	110-120
Color (Gardner)	5	4	3	<3	<3
Ash Content (ppm)	300	150	80	<50	<50
Metal Ions (ppb)	80	50	20	<10	<10

Economic Benefits: Yield: 92%

Cost and Revenue per Ton:

• Raw Material Cost: 20,000 CNY/ton

• Purified Selling Price: 80,000 CNY/ton

• Gross Profit per Ton: 60,000 CNY

Annual Production of 200 Tons Benefits:

• Annual Profit Increase: 12 million CNY

Appendix A  Testing standards for photoresist-grade phenolic resins

Test Items:	Standard methods:	Instruments and Equipment:
Molecular weight	GPC	Waters GPC, standard polystyrene
Hydroxyl content	Chemical titration	Potentiometric titrator
Softening point	GB/T 4507	Ring and ball softening point apparatus
Free phenol	GC-FID	Gas chromatograph
Free formaldehyde	HPLC	High-performance liquid chromatograph
Metal ions	ICP-MS	Inductively coupled plasma mass spectrometer
Ash content	GB/T 9345	Muffle furnace, 550℃ incineration
Color	Gardner method	Colorimeter
Moisture content	Karl Fischer	Karl Fischer moisture titrator

Appendix B: Frequently Asked Questions (FAQ)

Q1: Can molecular distillation be used to process solid phenolic resins?

A: Yes. It needs to be dissolved in a solvent (such as toluene, ethanol) or heated to a molten state (usually 80-120°C) before feeding.

Q2: Does the equipment require special explosion-proof requirements?

A: If flammable solvents (such as toluene, ethanol) are used, explosion-proof areas (such as Zone 2) need to be classified, equipped with explosion-proof motors and instruments.

Q3: Can thermosetting phenolic resins be processed?

A: We recommend processing thermoplastic (Novolac) type resins. Thermosetting (Resol) type resins are not suitable for molecular distillation due to their poor fluidity caused by partial cross-linking. If processing is necessary, it must be done in the liquid phase before curing.

Q4: How to store the purified resin?

A: It is recommended to store the product in a sealed container in a cool, dry place to prevent moisture absorption and oxidation. For photoresist-grade resins, storage under nitrogen protection is recommended, and the shelf life can reach 12 months.

Q5: How long does a single equipment cleaning take?

A: Approximately 2-4 hours. The process involves circulating solvents such as toluene or acetone, and the effect is enhanced by heating to 80-100℃. It is recommended to perform a thorough cleaning after every 10-20 batches.

Q6: Equipment footprint and height requirements?

A: YHMD-150 occupies approximately 15 m², equipment height approximately 3.5 meters, requires factory floor height ≥ 4.5 meters. If floor height is insufficient, horizontal structure can be customized.

Q7: Can multiple different grades of resin be processed simultaneously?

A: Yes, but cleaning is required between different batches to avoid cross-contamination. It is recommended to establish a product switching SOP to ensure batch-to-batch consistency.