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Basic introduction
Hydroxypropyl methyl cellulose, also known as hydroxypropyl methyl cellulose and cellulose hydroxypropyl methyl ether, is prepared from highly pure cotton cellulose by special etherification under alkaline conditions.
?? Main uses
1. Construction industry: As a water retaining agent and retarder of cement mortar, it makes the mortar pumpable. Use plaster, gypsum, putty powder or other building materials as adhesives to improve the applicability and prolong the operation time. It can be used to paste ceramic tile, marble, plastic decoration, paste reinforcing agent, and reduce the amount of cement. Hydroxypropyl methylcellulose HPMC water-retaining properties make the paste not crack because of drying too fast after smearing, and enhance the strength after hardening.
2. Ceramic manufacturing industry: widely used as adhesives in the manufacture of ceramic products.
3. Coatings industry: As a thickener, dispersant and stabilizer in the coating industry, it has good solubility in water or organic solvents. As paint remover.
4. Ink printing: As a thickener, dispersant and stabilizer in the ink industry, it has good solubility in water or organic solvents.
5. Plastics: as forming release agent, softener, lubricant, etc.
6. Polymerization: As dispersant in the production of polycondensation, it is the main assistant in 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 industry.
8. Pharmaceutical Industry: Coating Material; Membrane Material; Speed-Controlled Polymer Material for Sustained Release Agents; Stabilizer; Suspension Aid; Tablet Adhesive; Viscosifier
Chemical property
1. Appearance: White or similar white powder.
2. Particle size; 100 mesh pass rate is more than 98.5%; 80 mesh pass rate is 100%. Particle sizes of special specifications ranged from 40 to 60 meshes.
3. Carbonization temperature: 280-300 C
4. Visual density: 0.25-0.70g/cm (usually about 0.5g/cm), specific gravity 1.26-1.31.
5. Discoloration temperature: 190-200 C
6. Surface tension: 2% aqueous solution is 42-56 dyn/cm.
7. Solubility: Soluble in water and some solvents, such as appropriate proportion of ethanol/water, /water, etc. Aqueous solution has surface activity. With high transparency and stable performance, the gel temperature of different specifications is different, the solubility changes with viscosity, the viscosity is lower and the solubility is greater. The performance of HPMC with different specifications has certain difference. The dissolution of HPMC in water is not affected by pH value.
8, HPMC decreases with the decrease of methoxy content, the increase of gel point, the decrease of water solubility, and the decrease of surface activity.
9. HPMC also has the characteristics of thickening ability, salt-resistant low ash powder, pH stability, water-holding capacity, dimensional stability, excellent film-forming ability, and extensive enzyme resistance, dispersibility and cohesion.
Dissolution method
1. All models can be added to the material by dry mixing method.
2. When it needs to be added directly to the normal temperature water solution, it is better to use the cold water dispersion type, which can only be thickened in 10-90 minutes.
3. Ordinary models are first dispersed by hot water stirring, then cooled by cold water stirring to dissolve.
4. If the phenomenon of agglomeration and encapsulation occurs during dissolution, it is due to insufficient stirring or the direct addition of ordinary models to cold water. At this time, rapid stirring should be adopted.
5. If bubbles occur during dissolution, they can be removed by standing for 2-12 hours (the specific time depends on the consistency of the solution) or by vacuum or pressurization, or by adding appropriate defoamers.
synthetic method
1. The refined cotton cellulose was treated with alkali liquor at 35-40 ~C for half an hour, pressed, crushed and aged at 35 ~C appropriately, so that the average degree of polymerization of the obtained alkali fibers was within the required range. The alkali fibers were put into the etherification kettle, then added and etherified at 50-80 C for 5 hours, with the maximum pressure of about 1.8 MPa. Then add appropriate amount of hydrochloric acid and oxalic acid washing material in hot water at 90 ~C to make the volume expand. Dehydration by centrifuge. Wash to neutral, when the moisture content in the material is less than 60%, dry to below 5% by hot air flow at 130 C.
Determination method
Method Name: Hydroxypropyl methylcellulose - Determination of hydroxypropoxy group - Determination of hydroxypropoxy group
Scope of application: This method uses hydroxypropoxyl determination method to determine the content of hydroxypropoxyl in hydroxypropyl methylcellulose.
This method is suitable for HPMC.
Method Principle: The content of hydroxypropoxy group was calculated according to the method of hydroxypropoxy determination.
Reagent: 1.30% (g/g) solution
2. Hydrogen titration solution (0.02mol/L)
3. indicator solution
4.
5. rare
6. potassium iodide
7. Titration solution (0.02mol/L)
8. Starch Indicator
Instruments and equipment:
Sample preparation: 1. Hydrogen titration solution (0.02mol/L)
Preparation: Take 5.6 mL of clarified hydrogen saturated solution and add fresh boiled cold water to make 1000 mL.
Calibration: Take the standard potassium ammonium phthalate about 6g, which is dried to constant weight at 105 C, and weigh it precisely, add fresh boiled cold water 50mL, shake it to dissolve as far as possible; add two drops of indicator liquid and titrate it with this liquid. When approaching the end point, potassium hydrogen phthalate should be completely dissolved and titrated pink. Each mL of hydrogen titration solution (1 mol/L) is equivalent to 20.42 mg of potassium hydrogen phthalate. According to the consumption of the solution and the amount of potassium hydrogen phthalate, the concentration of the solution was calculated. Quantitative dilution was 5 times as high as 0.02mol/L.
Storage: In polyethylene plastic bottle, sealed storage; plug has 2 holes, each of which is inserted into a glass tube, one tube is connected with a sodium lime tube, and one tube is used for sucking out the liquid.
2. indicator solution
Take 1g and add 100mL ethanol to dissolve it.
3. Titration solution (0.02mol/L)
Preparation: Take 26G and anhydrous sodium carbonate 0.20g, add some fresh boiled cold water to dissolve into 1000 mL, shake well, place for 1 month and then filter.
Calibration: Take a reference weight of about 0.15g for drying constant weight at 120 C, weigh it accurately, put it in an iodine bottle, add water 50mL to dissolve, add potassium iodide 2.0g, shake it gently to dissolve, dilute it 40mL, shake it evenly and close; after 10 minutes in the dark, add water 250mL to dilute it, add starch indicator solution 3mL to titrate near the end point, and continue titration. The titration results were corrected by blank test. Each mL (0.1 mol/L) is equivalent to 4.903 g of weight. According to the consumption and weight of the solution, the concentration of the solution can be calculated. Quantitative dilution was 5 times as high as 0.02mol/L.
When the room temperature is above 25 C, the reaction liquid and dilution water should be cooled to about 20 C.
4. Starch Indicator
Take soluble starch 0.5g, add 5 ml water to mix, slowly pour into 100 mL boiling water, with stirring, continue to boil for 2 minutes, cool, pour supernatant, that is. The solution should be prepared in a new way.
Operation steps: Take 0.1g of this product, weigh it precisely, place it in distillation bottle D, add 30% (g/g) cadmium trichloride solution 10mL. Install water into the steam generator B to the joint and connect the distillation unit. B and D are immersed in oil bath (glycerol), so that the level of oil bath is consistent with that of cadmium trichloride solution in D bottle. Cooling water is opened and nitrogen flow is introduced when necessary, and the flow rate is controlled to 1 bubble per second. In 30 minutes, the oil bath was heated to 155oC, and the temperature was maintained until the distillate was collected at 50mL. The condensation tube was removed from the fractionation column, washed with water, washed and incorporated into the collection solution with 3 drops of indicator solution. The volume of V1 (mL) was titrated to pH 6.9-7.1 (determined by acidity meter), and then added 0.5g and dilute 10mL to stop production. To generate carbon dioxide, add potassium iodide 1.0g, dense, shake well, place in the dark for 5 minutes, add starch indicator solution 1mL, titrate with titration solution (0.02mol/L) to the end point, and record the volume of V2 (mL) consumed. The volumes of Va and Vb (mL) of consumed hydrogen titration solution (0.02mol/L) and titration solution (0.02mol/L) were recorded separately in blank test. The hydroxypropoxy content was calculated.
Renqiu Huabo Chemical Co., Ltd. is a company specializing in the production and processing of hydroxypropyl methyl cellulose, redispersible latex powder, carboxymethyl cellulose, carboxymethyl starch, polyacrylamide, paper dispersant, coal washing agent, petroleum drilling and mining, mineral processing agent, sewage treatment agent and other products. It has complete and scientific quality tube. Rationale system. Renqiu Huabo Chemical Co., Ltd. is recognized by the industry for its integrity, strength and product quality. Welcome friends from all walks of life to visit, guide and negotiate business.
Mr. Zhang Jianyang (General Manager of Sales Department)
Tel: 86 0317 2919299
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