Hydroxypropyl methyl cellulose, also known as hypromellose, cellulose hydroxypropyl methyl ether, is obtained by selecting highly pure cotton cellulose as raw material and specially etherified under alkaline conditions.
Chinese name
Hydroxypropylmethylcellulose
foreign name
Hydroxypropyl methyl cellulose
short name
HPMC cellulose
Exterior
white powder
English alias
HPMC
The main purpose
1. Construction industry: As a water-retaining agent and retarder for cement mortar, it makes the mortar pumpable. Used as a binder in plastering paste, gypsum, putty powder or other building materials to improve spreadability and prolong operation time. It is used as a paste for ceramic tile, marble, plastic decoration, as a paste enhancer, and it can also reduce the amount of cement. The water retention of HPMC can prevent the slurry from cracking due to drying too fast after application, and enhance the strength after hardening.
2. Ceramic manufacturing: widely used as a binder in the manufacture of ceramic products.
3. Coating industry: as a thickener, dispersant and stabilizer in the coating industry, it has good compatibility in water or organic solvents. as a paint remover.
4. Ink printing: as a thickener, dispersant and stabilizer in the ink industry, it has good compatibility in water or organic solvents.
5. Plastic: used as molding release agent, softener, lubricant, etc.
6. Polyvinyl chloride: It is used as a dispersant in the production of polyvinyl chloride, and it is the main auxiliary agent for the preparation of PVC by suspension polymerization.
7. Others: This product is also widely used in leather, paper products, fruit and vegetable preservation and textile industries.
8. Pharmaceutical industry: coating materials; film materials; rate-controlling polymer materials for sustained-release preparations; stabilizers; suspending agents; tablet binders; tackifiers
Hydroxypropyl methylcellulose molecular formula
Soluble in water and most polar c and appropriate proportions of ethanol/water, propanol/water, dichloroethane, etc., insoluble in ether, acetone, absolute ethanol, swelling into clear or slightly turbid colloids in cold water solution. The aqueous solution has surface activity, high transparency and stable performance. HPMC has the property of thermal gelation. The aqueous solution of the product is heated to form a gel and precipitate, and then dissolves after cooling. The gel temperature of products with different specifications is different. The solubility changes with the viscosity. The lower the viscosity, the greater the solubility. The properties of HPMC of different specifications are different. The dissolution of HPMC in water is not affected by the pH value. Particle size: 100 mesh pass rate is greater than 98.5%. Bulk density: 0.25-0.70g/ (usually about 0.4g/), specific gravity 1.26-1.31. Discoloration temperature: 180-200℃, carbonization temperature: 280-300℃. The methoxy value is 19.0% to 30.0%, and the hydroxypropyl value is 4% to 12%. Viscosity (22℃, 2%) 5～200000mPa.s. Gel temperature (0.2%) 50-90 ℃. HPMC has the characteristics of thickening ability, salt expulsion, pH stability, water retention, dimensional stability, excellent film-forming properties, and a wide range of enzyme resistance, dispersibility and cohesiveness.
chemical properties
1. Appearance: white or off-white powder.
2. Particle size; 100 mesh pass rate is greater than 98.5%; 80 mesh pass rate is 100%. The particle size of special specifications is 40-60 mesh.
3. Carbonization temperature: 280-300℃
Hydroxypropylmethylcellulose
4. Apparent density: 0.25-0.70g/cm (usually around 0.5g/cm), specific gravity 1.26-1.31.
5. Color changing temperature: 190-200℃
6. Surface tension: 2% aqueous solution is 42-56dyn/cm.
7. Solubility: soluble in water and some solvents, such as ethanol/water, propanol/water, etc. in an appropriate proportion. Aqueous solutions are surface active. High transparency and stable performance. Different specifications of products have different gel temperatures, and solubility changes with viscosity. The lower the viscosity, the greater the solubility. Different specifications of HPMC have different properties. The dissolution of HPMC in water is not affected by pH value.
8. With the decrease of methoxy group content, the gel point increases, the water solubility decreases, and the surface activity of HPMC decreases.
9. HPMC also has the characteristics of thickening ability, salt resistance, low ash powder, pH stability, water retention, dimensional stability, excellent film-forming properties, and a wide range of enzyme resistance, dispersibility and cohesiveness.
Dissolution method
1. All models can be added to the material by dry mixing;
2. When it needs to be directly added to the normal temperature aqueous solution, it is best to use the cold water dispersion type. After adding, it usually takes 10-90 minutes to thicken;
3. Ordinary models can be dissolved by stirring and dispersing with hot water first, then adding cold water, stirring and cooling;
4. If there is agglomeration and wrapping during dissolving, it is because the stirring is not sufficient or the ordinary model is directly added to the cold water. At this time, it should be stirred quickly.
5. If bubbles are generated during dissolution, it can be left for 2-12 hours (the specific time is determined by the consistency of the solution) or removed by vacuuming, pressurizing, etc., or adding an appropriate amount of defoaming agent.
resolve resolution
1. Treat the refined cotton cellulose with alkali solution at 35-40℃ for half an hour, press, pulverize the cellulose, and properly age at 35℃, so that the average degree of polymerization of the obtained alkali fiber is within the required range. Put the alkali fiber into the etherification kettle, add propylene oxide and methyl chloride in turn, and etherify at 50-80℃ for 5h, the maximum pressure is about 1.8MPa. Then add an appropriate amount of hydrochloric acid and oxalic acid to the hot water at 90 ° C to wash the material to expand the volume. Dehydrate with a centrifuge. Wash until neutral, when the water content in the material is less than 60%, dry it with a hot air flow at 130°C to less than 5%.
test methods
Method name: Hypromellose—Determination of hydroxypropoxyl groups—Determination of hydroxypropoxyl groups
Scope of application: This method adopts the hydroxypropoxy determination method to determine the content of hydroxypropoxy in hypromellose.
This method is applicable to hypromellose.
Method principle: Calculate the content of hydroxypropoxy group according to the hydroxypropoxy group determination method.
Reagent: 1. 30% (g/g) chromium trioxide solution
2. Sodium hydroxide titrant (0.02mol/L)
3. Phenolphthalein indicator solution
4. Sodium Bicarbonate
5. Dilute sulfuric acid
6. Potassium iodide
7. Sodium thiosulfate titration solution (0.02mol/L)
8. Starch indicator solution
equipment:
Sample preparation: 1. Sodium hydroxide titration solution (0.02mol/L)
Preparation: Take 5.6mL of clear saturated sodium hydroxide solution, add freshly boiled cold water to make 1000mL.
Calibration: Take about 6g of benchmark potassium hydrogen phthalate dried to constant weight at 105℃, accurately weigh, add 50mL of freshly boiled cold water, shake to dissolve as much as possible; add 2 drops of phenolphthalein indicator solution, use this Titrate. When approaching the end point, the potassium hydrogen phthalate should be completely dissolved, and the solution should be titrated to a pink color. Each 1mL of sodium hydroxide titration solution (1mol/L) is equivalent to 20.42mg of potassium hydrogen phthalate. Calculate the concentration of this solution according to the consumption of this solution and the amount of potassium hydrogen phthalate taken. Quantitatively diluted 5 times to make the concentration 0.02mol/L.
Storage: Put it in a polyethylene plastic bottle and keep it sealed; there are 2 holes in the stopper, and a glass tube is inserted into each hole.
2. Phenolphthalein indicator solution
Take 1g of phenolphthalein, add 100mL of ethanol to dissolve
3. Sodium thiosulfate titration solution (0.02mol/L)
Preparation: Take 26g of sodium thiosulfate and 0.20g of anhydrous sodium carbonate, add an appropriate amount of freshly boiled cold water to dissolve into 1000mL, shake well, and filter after standing for 1 month.
Calibration: Take about 0.15g of benchmark potassium dichromate dried at 120°C with constant weight, accurately weigh it, put it in an iodine bottle, add 50mL of water to dissolve, add 2.0g of potassium iodide, shake gently to dissolve, add 40mL of dilute sulfuric acid, Shake well and seal it tightly; after 10 minutes in the dark, add 250 mL of water to dilute it, when the titration is near the end point, add 3 mL of starch indicator solution, continue to titrate until the blue disappears and the green becomes bright, and the titration result is blank. Trial correction. Each 1mL of sodium thiosulfate (0.1mol/L) is equivalent to 4.903g of potassium dichromate. Calculate the concentration of this solution according to the consumption of this solution and the amount of potassium dichromate taken. Quantitatively diluted 5 times to make the concentration 0.02mol/L.
If the room temperature is above 25°C, the reaction solution and dilution water should be cooled to about 20°C.
4. Starch indicator solution
Take 0.5 g of soluble starch, add 5 mL of water and mix well, slowly pour it into 100 mL of boiling water, stir as it is added, continue to boil for 2 minutes, let it cool, and pour out the supernatant. This solution should be used in a new system.
Operation steps: Take 0.1 g of this product, accurately weigh it, put it in distillation flask D, and add 10 mL of 30% (g/g) cadmium trichloride solution. Put water into the steam generating pipe B to the joint, and connect the distillation device. Immerse both B and D in the oil bath (it can be glycerin), make the oil bath liquid level consistent with the liquid level of the cadmium trichloride solution in the D bottle, turn on the cooling water, and if necessary, introduce nitrogen flow and control its flow rate to be every 1 bubble per second. The oil bath was heated to 155°C within 30 minutes, and the temperature was maintained until 50 mL of distillate was collected. The condenser was removed from the fractionation column, rinsed with water, washed and merged into the collected solution, and 3 drops of phenolphthalein indicator solution were added. Titrate to the pH value of 6.9-7.1 (measured with an acidity meter), record the consumed volume V1 (mL), then add 0.5 g of sodium bicarbonate and 10 mL of dilute sulfuric acid, let it stand until no carbon dioxide is produced, add 1.0 g of potassium iodide, Close the plug, shake well, place in a dark place for 5 minutes, add 1 mL of starch indicator solution, titrate to the end point with sodium thiosulfate titration solution (0.02mol/L), and record the consumed volume V2 (mL). Another blank test was performed, and the volumes Va and Vb (mL) of the consumed sodium hydroxide titration solution (0.02mol/L) and sodium thiosulfate titration solution (0.02mol/L) were recorded respectively. Calculate the hydroxypropoxy content.
Note: “Precision weighing” means that the weighing should be accurate to one thousandth of the weight.
Safety performance
health hazard
This product is safe and non-toxic, can be used as a food additive, has no heat, and is non-irritating to skin and mucous membranes. Generally considered to be safe (FDA1985), the allowable daily intake is 25mg/kg (FAO/WHO 1985), and protective equipment should be worn during operation.
environmental impact
Avoid random scattering to cause dust to fly and cause air pollution.
Physical and chemical hazards: Avoid contact with fire sources, and avoid the formation of a large amount of dust in a closed environment to prevent explosion hazards.
Transportation and storage matters
Pay attention to sunscreen, rainproof, moistureproof, avoid direct sunlight, and store in a dry place.
Application field
construction industry
1. Cement mortar: improve the dispersibility of cement-sand, greatly improve the plasticity and water retention of mortar, and effectively prevent cracks and enhance the strength of cement.
2. Tile cement: Improve the plasticity and water retention of the pressed tile mortar, improve the bonding force of the tiles, and prevent pulverization.
3. Coating of refractory materials such as asbestos: as a suspending agent, a fluidity improver, and also to improve the bonding force to the substrate.
4. Gypsum coagulation slurry: improve water retention and processability, and improve adhesion to the substrate.
5. Joint cement: added to the joint cement for gypsum board to improve fluidity and water retention.
6. Latex putty: Improve the fluidity and water retention of putty based on resin latex.
7. Stucco: As a paste instead of natural materials, it can improve water retention and improve the bonding force with the substrate.
8. Coating: As a plasticizer for latex coatings, it has a role in improving the operational performance and fluidity of coatings and putty powder.
9. Spray coating: It has a good effect on preventing cement-based or latex-based spraying only material filler from sinking and improving fluidity and spray pattern.
10. Secondary products of cement and gypsum: It is used as extrusion molding binder for hydraulic materials such as cement-asbestos to improve fluidity and obtain uniform molded products.
11. Fiber wall: It is effective as a binder for sand walls due to its anti-enzyme and anti-bacterial effects.
12. Others: It can be used as a bubble retainer for thin mortar and plasterer operators (PC version).
chemical industry
1. Polymerization of vinyl chloride and vinylidene: As a suspension stabilizer and dispersant during polymerization, it can be used together with vinyl alcohol (PVA) hydroxypropyl cellulose (HPC) to control particle shape and particle distribution.
2. Adhesive: As the adhesive of wallpaper, it can usually be used together with vinyl acetate latex paint instead of starch.
3. Pesticides: when added to pesticides and herbicides, it can improve the adhesion effect during spraying.
4. Latex: improve the emulsion stabilizer of asphalt latex, and the thickener of styrene-butadiene rubber (SBR) latex.
5. Binder: used as a molding adhesive for pencils and crayons.
Cosmetics
1. Shampoo: Improve the viscosity of shampoo, detergent and detergent and the stability of air bubbles.
2. Toothpaste: Improve the fluidity of toothpaste.
food industry
1. Canned citrus: to prevent whitening and deterioration due to the decomposition of citrus glycosides during storage to achieve the effect of preservation.
2. Cold food fruit products: add to sherbet, ice, etc. to make the taste better.
3. Sauce: as an emulsifying stabilizer or thickening agent for sauces and ketchup.
4. Coating and glazing in cold water: It is used for frozen fish storage, which can prevent discoloration and deterioration of quality. After coating and glazing with methyl cellulose or hydroxypropyl methyl cellulose aqueous solution, it is then frozen on ice.
Post time: Feb-20-2025