(1) Determination of HPMC viscosity: The dried product is prepared into an aqueous solution with a weight concentration of 2 °C, and is measured by an NDJ-1 type rotational viscometer;
(2) The appearance of the product is powder, and the instant product is suffixed with “s” in the brand name.
How to use hydroxypropyl methylcellulose?
It is directly added during production. This method is the simplest and the shortest time-consuming method. The specific steps are:
1. Add a certain amount of boiling water to a stirring vessel with high shear stress (the hydroxyethyl cellulose product is soluble in cold water, so just add cold water);
2. Turn on the stirring at low speed, and slowly sieve the product into the stirring container;
3. Continue stirring until all particles are soaked through;
4. Add enough cold water and continue to stir until all the products are completely dissolved (the transparency of the solution is obviously increased);
5. Then add the other ingredients in the formula.
Prepare the mother liquor for use: This method is to prepare the product into a mother liquor with a higher concentration, and then add it to the product. The advantage is that it has greater flexibility and can be directly added to the finished product. The steps are the same as (1-3) in the direct addition method. After the product is fully wet, let it stand for natural cooling to dissolve, and then fully stir before use. It should be noted that the antifungal agent must be added to the mother liquor as soon as possible.
Dry mixing use: After fully dry mixing the powder product and powder materials (such as cement, gypsum powder, ceramic clay, etc.), add an appropriate amount of water, and fully knead and stir until the product is completely dissolved.
Dissolution of cold water soluble products: cold water soluble products can be directly added to cold water for dissolution. After adding cold water, the product will sink quickly. After being wet for a certain period of time, start stirring until it is completely dissolved.
Precautions when preparing solutions
(1) Products without surface treatment (except hydroxyethyl cellulose) shall not be directly dissolved in cold water;
(2) It must be slowly sieved into the mixing container, and do not directly add the product that has been formed into a block into the mixing container in large quantities;
(3) The pH value of water temperature and water has a significant relationship with the dissolution of the product, and special attention must be paid;
(4) Do not add some alkaline substances to the mixture before the product powder is soaked with water, and increase the pH value after soaking, which will help dissolve;
(5) As far as possible, add antifungal agent in advance;
(6) When using high-viscosity products, the weight concentration of the mother liquor should not be higher than 2.5-3%, otherwise the mother liquor is difficult to operate;
(7) Products that have undergone instant treatment shall not be used in food or pharmaceutical products.