Propylene Glycol (PG) – CAS No. 57-55-6

Product Overview

Propylene Glycol (PG), with the chemical formula C₃H₈O₂ and CAS Number 57-55-6, is a versatile, multi-functional diol widely employed as a humectant, solvent, and carrier in food, pharmaceuticals, cosmetics, and industrial applications. This clear, colorless, odorless viscous liquid demonstrates complete miscibility with water and most organic solvents, with a neutral pH of 6.0-8.0 in 10% solution, ensuring seamless integration without altering formulation stability or sensory attributes. With a purity ≥99.5%, PG retains moisture, dissolves active ingredients, and provides freeze-thaw protection, making it indispensable for preserving texture in bakery goods, enhancing drug solubility, and stabilizing emulsions in skincare. Its low toxicity and biodegradability support clean-label and sustainable product development, delivering consistent performance across temperature ranges from -60°C to 150°C.

Key benefits of Propylene Glycol include:

  • Superior Humectancy: Attracts and retains moisture, preventing dryness in foods and cosmetics.
  • Solvent Efficiency: Dissolves polar and non-polar substances for uniform blends and rapid absorption.
  • Thermal Stability: Low freezing point (-59°C) and high boiling point (188°C) for antifreeze and heat transfer uses.
  • Non-Toxic Profile: GRAS by FDA, safe for oral and topical applications with no cumulative effects.
  • Versatile Compatibility: Stable with surfactants, emulsifiers, and preservatives across pH 3-10.

Propylene Glycol is produced via catalytic hydration of propylene oxide, yielding a high-purity, low-residue product compliant with USP, FCC, and EP pharmacopeia standards.

Items Unit Specification Results
Identification — passed passed
Appearance — Colorless clear viscous liquid Colorless clear viscous liquid
Assay % 99.80 min 99.92
EG ppm 50max 0
DEG ppm 50max 0
Residue on lgnition mg 2.5max 0.8
Chloride Weight % 0.007max <0.007
Sulfate Weight% 0.006max <0.006
Heavy metals ppm 5max <5
Specific Gravity 25℃ 1.035-1.037 1.0354
Acidity(0.1N NaOH) ml 0.05max 0.03
Moisture Weight % 0.10max 0.050
Fe ppm 0.1max 0
Color Pt-Po 10max <10
IBP ℃ 184 185
DP ℃ 189 187

Applications

Food and Beverage Industry

  • Moisture Retention: Added at 5-20% in icings, marshmallows, and soft drinks to maintain tenderness and prevent crystallization.
  • Flavor Carrier: 1-5% in extracts and syrups to solubilize oils and enhance mouthfeel without bitterness.

Pharmaceuticals and Cosmetics

  • Drug Delivery: Solvent at 10-30% in oral liquids and topicals for improved bioavailability and skin penetration.
  • Emulsion Stabilizer: 2-10% in creams and lotions for phase stability and humectancy in moisturizers.

Industrial Uses

  • Antifreeze and Coolants: 30-50% in heat transfer fluids for HVAC systems, providing burst protection down to -50°C.
  • Unsaturated Polyester Resins: Reactive diluent at 5-15% for gel coats and laminates, reducing viscosity without compromising strength.

Why Choose Our Propylene Glycol?

Our Propylene Glycol is derived from bio-based propylene with advanced distillation, ensuring diol content >99.7% and heavy metals <1 ppm for exceptional purity and odor neutrality. Formulators experience 20% better emulsion longevity and reduced microbial growth. Available in USP/food/pharma/technical grades, packaged in 230kg drums or 1000kg IBCs, with Kosher, Halal, and Non-GMO certifications for seamless regulatory compliance.

Frequently Asked Questions (FAQs)

What is Propylene Glycol (PG)?

Propylene Glycol (PG) is a diol compound with formula C₃H₈O₂ and CAS 57-55-6, used as a humectant and solvent. It’s a colorless liquid that retains moisture and dissolves ingredients in food, pharma, and cosmetics.

How is Propylene Glycol used in food products?

Incorporate at 2-15% during mixing to prevent drying in baked goods or as a carrier in flavors; it’s FDA GRAS for direct addition up to 2.0% in most categories.

Is Propylene Glycol safe for skin care?

Yes, PG is CIR-approved up to 50% in leave-on products, with low irritation potential and rapid evaporation for non-greasy feel in serums and gels.

What is the shelf life of Propylene Glycol?

Stored in sealed, cool conditions (<30°C), PG maintains stability for 2-3 years, resistant to oxidation and microbial contamination.

Can Propylene Glycol be used in antifreeze?

PG is ideal for non-toxic antifreeze at 40-60% concentrations, offering protection to -50°C while being safe for RV and food-grade systems.

Does Propylene Glycol affect product viscosity?

PG’s moderate viscosity (40 cP) acts as a thickener in low doses but dilutes at higher levels—optimal for balancing flow in lotions and syrups.

What packaging options are available for Propylene Glycol?

We supply 230kg steel drums, 1000kg HDPE IBCs, and 20MT bulk tankers, all lined for purity preservation and UN-compliant shipping.

For formulation tips, safety data, or custom grades, our specialists provide expert guidance.

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