Polypropylene glycol PPG-400 (CAS No.: 25322-69-4) is a non-ionic surfactant and polyol with a molecular weight of approximately 380~420. Its molecular chain contains ether bonds and primary hydroxyl groups, endowing it with excellent solubility, lubricity, and chemical reactivity. In practical use, PPG-400 can be incorporated into formulations or processes in various ways: as a direct additive to perform physical functions such as wetting, lubrication, and moisturizing; as a reactive intermediate, where its terminal hydroxyl groups can undergo polycondensation or esterification reactions with isocyanates, organic acids, etc., to produce polyurethanes or ester derivatives; it can also serve as a solubilizer or co-solvent to help uniformly disperse other components in the system.
At room temperature, this product is a viscous liquid (kinematic viscosity at 40°C approx. 70 mm²/s). Its viscosity increases significantly at low temperatures, but it remains fluid (melting point below -30°C). For ease of operation and measurement, it is recommended to use it at 15~35°C. To reduce viscosity for convenient pouring or pumping, the packaging drum can be moderately preheated before use (e.g., water bath at 40~60°C or storage in a warm room). Direct open flame heating is strictly prohibited. After preheating, stir or circulate thoroughly to ensure uniform temperature distribution and avoid local overheating.
PPG-400 is readily soluble in water and various organic solvents such as alcohols, esters, and ketones. It is chemically stable and resistant to acids, alkalis, and hard water. When adding to a formulation, the principle of "slowly add while stirring" is generally followed to ensure uniform dispersion. If used in polyurethane synthesis, vacuum dehydration is typically required before feeding (e.g., at 100~120°C, vacuum degree above -0.09MPa, for 1~2 hours) to remove potentially adsorbed trace moisture, preventing moisture from reacting with isocyanates to generate carbon dioxide bubbles, which would affect product performance.
| Parameter Item | Specification / Typical Data | Description |
|---|---|---|
| Appearance | Colorless to slightly yellowish transparent viscous liquid | Visual inspection for product purity and stability |
| Average Molecular Weight | 380~420 | Determines reactivity and physical properties |
| Hydroxyl Value (mg KOH/g) | 260~300 | Measures terminal hydroxyl content, directly determines reaction equivalent |
| Water Content | ≤0.1% | Must be strictly controlled for polyurethane applications |
| Acid Value (mg KOH/g) | ≤0.1 | Affects reaction rate and product performance |
| Kinematic Viscosity (40°C) | Approx. 70 mm²/s | Affects handling and processing fluidity |
| Density (25°C) | 1.004~1.010 | Used for material measurement and formulation conversion |
| Flash Point (Closed Cup) | ≥200°C | Safety indicator |
| HLB Value | Approx. 2.0 | Strong lipophilicity, suitable for water-in-oil or low-foam systems |
| Cloud Point (1% Aqueous Solution) | Approx. 50°C | Reverse solubility characteristic |
| pH Value (1% Aqueous Solution) | 6.0~8.0 | Nearly neutral, good formulation adaptability |
| Iodine Value | ≤0.1 | Extremely low unsaturation, good chemical stability |
1. Polyurethane Industry (Flexible/Rigid Foam, Elastomers, Coatings, Adhesives)
As a soft segment polyol component, the recommended dosage of PPG-400 is typically 5%~80% of the total polyol content (adjusted based on desired flexibility and hardness). Strict dehydration is required before use (suggested vacuum dehydration at 100~120°C). Then, mix and react with isocyanates (e.g., TDI, MDI), catalysts, blowing agents, foam stabilizers, etc., according to the established formulation. In polyurethane elastomers or coatings, PPG-400 can enhance film flexibility and hydrolysis resistance.
2. Synthetic Lubricants and Functional Fluids
It can be directly used as base oil or co-solvent component for industrial gear oils, high-temperature chain oils, and compressor oils, with a typical addition amount of 10%~50%. Its excellent viscosity-temperature characteristics and low carbon deposit tendency make it suitable for high-temperature conditions. It can also be modified by esterification before use to achieve a wider operating temperature range and improved compatibility. In metalworking fluids, as a lubricating component, a recommended addition amount of 5%~20% is suggested.
3. Surfactants and Textile Auxiliaries
As a non-ionic surfactant intermediate, PPG-400 can undergo esterification or etherification to produce efficient emulsifiers, dispersants, or defoamers. In industrial cleaning formulations, as a low-foam wetting and penetrating component, a recommended addition amount of 1%~10% is suggested. In textile oils, it can improve fiber smoothness and antistatic properties, with dosage determined based on oil pick-up requirements.
4. Personal Care and Cosmetics
In creams, lotions, and facial cleansers, it acts as a humectant and lubricating emollient. It is typically added during the heating phase of the water or oil phase, stirring until completely dissolved and uniform. The recommended addition amount is 1%~5%. Its low tackiness and good spreadability effectively improve product skin feel. Its skin non-irritancy and non-sensitization (verified by animal tests) make it suitable for developing products for infants, children, and sensitive skin.
5. Pharmaceutical Applications
It can be used as a consistency regulator for suppository bases and ointment bases, or as a solubilizer for drugs. In suppository preparation, it is often compounded with other polyethylene glycols (e.g., PEG) to adjust the melting temperature and hardness of the suppository by varying the PPG-400 ratio. During use, comply with Good Manufacturing Practice (GMP) requirements to ensure material hygiene and safety, and operate in a clean environment.
6. Other Industrial Applications
As a defoamer raw material, PPG-400, due to its low HLB value (approx. 2.0) and low-foam characteristics, is often compounded with hydrophobic silica to prepare high-efficiency defoamers. The recommended dosage is 30%~70% of the defoamer formulation. As a mold release agent component, it can be sprayed directly or after dilution onto the mold surface to form an extremely thin release film. As a heat transfer fluid, it should be used in a closed-loop system, with a recommended operating temperature range not exceeding 200°C.