I. Product Overview

Hydroxypropyl Methylcellulose (HPMC), also known as Hypromellose, is a non-ionic cellulose mixed ether. It is a semi-synthetic high-molecular polymer produced by alkalizing natural materials (such as cotton linter or wood pulp) followed by etherification with propylene oxide and methyl chloride. HPMC appears as a white or off-white powder, is odorless, tasteless, and non-toxic. It possesses excellent thickening, binding, emulsifying, dispersing, water-retaining, and film-forming properties, leading to its use in a wide range of applications.

II. Physicochemical Properties

HPMC possesses a unique thermal gelation property — when an aqueous solution is heated to a specific temperature (depending on the degree of substitution), it forms a gel, which returns to a solution upon cooling. Various viscosity grades are available, ranging from low viscosity (e.g., 3 mPa·s) to high viscosity (e.g., 100,000 mPa·s), meeting diverse application requirements.

III. Key Characteristics

1. Thickening: Imparts the necessary viscosity to aqueous solutions and suspensions, preventing the sedimentation of solid particles.

2. Water Retention: Excellent water retention capacity ensures complete hydration of cement, gypsum, and other binding materials, enhancing final strength.

3. Film-Forming: Dries to form a transparent, tough film that provides a certain barrier against oils and organic solvents.

4. Binding/Adhesion: Exhibits good adhesion to various substrates (e.g., tiles, walls, pharmaceutical powder particles).

5. Emulsification & Dispersion: Helps stabilize oil-in-water emulsions and promotes the uniform dispersion of solid particles.

6. Thermal Gelation: Forms a gel upon heating to a specific temperature and returns to a fluid state upon cooling.

7. Enzyme Resistance: Not easily decomposed by microorganisms, offering good storage stability.

IV. Applications

1. Building Materials

HPMC is most widely used in the building materials sector, primarily as a water-retention agent and thickener in cement and gypsum plasters, putties, tile adhesives, exterior insulation finishing systems (EIFS), self-leveling floor compounds, and more. Its functions include:

• Improving workability and anti-sag properties of mortars

• Extending open time for easier application

• Enhancing bond strength and crack resistance

• Improving surface smoothness and fineness

2. Food Industry

As a food additive (E464), HPMC is used as:

• An emulsifier and stabilizer

• A thickener and suspending agent

• A quality improver for plant-based meat products and baked goods

• A raw material for vegetarian capsules

3. Daily Chemicals & Cosmetics

• Thickener and stabilizer in toothpaste, shampoos, and shower gels

• Emulsifying stabilizer for lotions and creams

• Film-former and thickener in face masks and skincare products

4. Other Industrial Applications

• Synthetic Resins & Paints/Coatings: Used as a protective colloid, thickener, and leveling agent.

• Petrochemicals: Additive for drilling fluids.

• Ceramic Industry: Binder for green bodies and suspending agent for glazes.

• Textile & Printing: Thickener for printing pastes and sizing agent.

V. Dissolution Methods

HPMC is categorized into two types based on its dissolution characteristics: Instant (Cold Water Dispersible) and Hot Soluble (Regular) .

1. Instant Type (Cold Water Dispersible) :

   • Added directly to cold water, it disperses and hydrates rapidly, gradually increasing viscosity after about 2 minutes to form a clear colloidal solution.

   • Suitable for liquid systems such as liquid adhesives, paints, and household chemical products.

2. Hot Soluble Type (Regular) :

   • Requires dry mixing with other powder ingredients before adding water.

   • Alternatively, use the hot-cold water method: first disperse in 1/3 of the required hot water (80-90°C), then add the remaining 2/3 cold water while stirring.

   • Suitable for dry-mix mortars, putties, and other powder products.

VI. Packaging and Storage

• Packaging: Multi-layer paper bags with a polyethylene liner or fiber drums, net weight 25 kg.

• Storage Conditions: Store in a dry, well-ventilated, cool place, protected from moisture, rain, and direct sunlight.

• Shelf Life: Typically 2 years; usable after re-inspection if stored properly.

VII. Precautions

1. HPMC is a non-ionic ether with good compatibility with most anionic and cationic surfactants, but salting out may occur with high concentrations of electrolytes.

2. Avoid lumping during dissolution; follow the correct addition order and mixing procedure.

3. Different grades of HPMC (varying in viscosity and substitution degree) have significantly different properties; select the appropriate type based on the specific application.

4. In mortar systems, it can be used in combination with starch ethers to achieve better anti-sag performance.