Dipropylene Glycol (DPG)
High-purity polyol solvent, humectant, and resin modifier
Overview
Dipropylene glycol (CAS No: 25265-71-8), also known as DPG, is a colorless, slightly viscous liquid. It has a mild sweetish odor and is a propylene glycol dimer. This organic compound is a versatile solvent and humectant widely used in cosmetics, personal care products, resins, and oil-based paints.
Dipropylene glycol is miscible with water and many organic solvents. Due to its low volatility, high solvency power, and low toxicity, it is preferred in many applications. It is also an excellent plasticizer and resin modifier.
Applications
Dipropylene glycol has diverse industrial, cosmetic, and consumer applications:
Cosmetics and Personal Care
Use as a humectant, solvent, and carrier in lotions, creams, perfumes, and deodorants.
Paints and Coatings
Use as a solvent, resin modifier, and brush softener in oil-based paints.
Resins and Polyurethanes
Use as a reactive diluent and plasticizer in polyester and polyurethane resins.
Cleaning Products
Use as a solvent and degreaser in surface cleaners.
Construction Chemicals
Use in cement admixtures and epoxy systems.
Agricultural Chemicals
Use as a solvent and carrier in pesticide and herbicide formulations.
Technical Specifications
| Property | Value | Unit | Test Method |
|---|---|---|---|
| Chemical Formula | C₆H₁₄O₃ | - | - |
| CAS Number | 25265-71-8 | - | - |
| Molecular Weight | 134.17 | g/mol | - |
| Appearance | Colorless liquid | - | Visual |
| Odor | Slightly sweet | - | Olfactometry |
| Density (20°C) | 1.020-1.025 | g/cm³ | ASTM D4052 |
| Boiling Point | 230-232 | °C | ASTM D1078 |
| Melting Point | -40 | °C | ASTM D1015 |
| Flash Point | 124 | °C | ASTM D93 |
| Auto-ignition Temperature | 271 | °C | ASTM E659 |
| Vapor Pressure (20°C) | <0.1 | kPa | ASTM D2879 |
| Viscosity (20°C) | 110 | cP | ASTM D445 |
| pH Value | 6-8 | - | ASTM E70 |
| Purity (GC) | ≥99.0 | % | ASTM D3545 |
| Water Content | ≤0.2 | % | ASTM E203 |
| Hydroxyl Value | 830-870 | mg KOH/g | ASTM E222 |
Safety Information
Hazard Symbols and Statements
Flammable Skin and eye irritation Health hazard
Personal Protective Equipment (PPE)
- Chemical-resistant gloves (nitrile or neoprene)
- Protective eyewear or face shield
- Adequate ventilation should be provided
- Chemical-resistant apron or work clothes
Storage Conditions
- Store in a cool, dry, well-ventilated area
- Keep in original closed containers, protected from sunlight
- Store separately from oxidizing agents
- Storage temperature: 15-30°C
- Store in stainless steel, polyethylene, or glass containers
Fire Fighting
- Suitable extinguishing agents: Foam, CO₂, dry chemical, or water mist
- Do not use water jet - may cause splattering
- Fight fire with trained personnel using appropriate respiratory protection
- Use alcohol-resistant foam for large fires
Handling and Storage
Handling
- Ensure containers are tightly closed during transport
- Provide adequate ventilation in transport vehicles
- Avoid eating, drinking, or smoking while handling
- Perform leak checks
- Use containers labeled "Flammable Liquid"
Storage
- Store in stainless steel, polyethylene, or glass containers
- Provide appropriate signage in storage area
- Use appropriate breathing vents on storage tanks
- Ground to prevent static electricity buildup
- Prohibit smoking in storage areas
Spill Response Measures
- Use appropriate respiratory protection
- Absorb spills with sand, chemical absorbent, or other absorbent materials
- Dispose of absorbed material appropriately
- Wash spill area with plenty of water and detergent
- Prevent spills from entering sewers or water sources
Regulatory Information
GHS Classification
- Flammable Liquid Category 4
- Skin Irritation Category 2
- Specific Target Organ Toxicity (Single Exposure) Category 3
Important Regulations
- REACH: Registered
- CLP: Compliant
- FDA: Food contact approved (21 CFR 175.300)
- NFPA 704: Health 1, Flammability 1, Reactivity 0
International Legislation
- European Union: Cosmetics Regulation (EC) No 1223/2009
- USA: Listed on TSCA inventory
- China: Listed on IECSC inventory
- Japan: Listed on ISHL inventory
Environmental Information
Environmental Impact
Dipropylene glycol is biodegradable in nature and moderately toxic to aquatic organisms. When mixed with water sources, it may have adverse effects on aquatic life. However, its high water solubility and low vapor pressure limit its atmospheric distribution.
Biological Degradation
- Air: 10-20 day half-life through photochemical reactions
- Water: Degrades within 7-14 days through microbial activity
- Soil: Moderate degradation rate through microbial activity
- Biological Oxygen Demand (BOD): 50% (28 days)
- Chemical Oxygen Demand (COD): 1.9 g O₂/g
Waste Management
- Not classified as hazardous waste
- Small quantities can be diluted with plenty of water and sent to sewer
- Large quantities should be incinerated in licensed hazardous waste disposal facilities
- Dispose according to local regulations
- Readily biodegradable in wastewater treatment plants
Frequently Asked Questions
How is dipropylene glycol produced?
Dipropylene glycol is produced by further reaction of propylene glycol formed from the reaction of propylene oxide with water. This process is carried out under controlled conditions in the presence of catalysts and yields a mixture of different isomers.
What is the difference between dipropylene glycol and propylene glycol?
Dipropylene glycol (C₆H₁₄O₃) is a dimer formed by the combination of two propylene glycol molecules (C₃H₈O₂). It has a higher boiling point, lower volatility, and higher viscosity compared to propylene glycol. Solvent properties also differ.
Why is dipropylene glycol used in cosmetics?
Dipropylene glycol is used in cosmetics as a humectant, solvent, and carrier. Its mild nature, low toxicity, and compatibility with other cosmetic ingredients make it preferable. It also helps extend product shelf life.
What is the shelf life of dipropylene glycol?
When stored properly in closed containers, dipropylene glycol has a shelf life of typically 2-3 years. It should be protected from moisture and temperature fluctuations.
What should I do if dipropylene glycol contacts my skin?
Wash with plenty of soap and water. Prolonged contact may cause skin dryness, using moisturizer may be beneficial. Seek medical attention if irritation persists. For eye contact, flush with plenty of water for at least 15 minutes and consult an eye doctor.