Preparation formula of screen printing paste

　　Sodium alginate has simple operation and strong paste-forming ability. According to the viscosity, sodium alginate is divided into three specifications: high, medium and low. When making paste, the temperature is not easy to be too high, which avoids the degradation of molecular chains and obviously reduces the viscosity. For example, when heated at 95℃ for 1 hour, the viscosity will decrease by 17% ~ 35%; When heated at 80℃ for 1 hour, the viscosity only decreases by about 5%, so the temperature should not exceed 80℃. Generally, it is prepared with warm water of 40 ~ 50℃.

Ordinary sodium alginate paste contains 4% ~ 8% sodium alginate, high viscosity paste contains about 3%, and low viscosity paste contains 12% ~ 15%. High viscosity is suitable for introducing cellulose fiber textiles, while low viscosity is suitable for printing synthetic fibers and silk textiles. In order to prevent the influence of calcium ions, 0.25% ~ 0.5% sodium hexametaphosphate can be added to the original paste, and the pH value can be adjusted to 7 ~ 8 with soda ash. Adding a small amount of triethanolamine can improve the stability of caustic soda. Sodium alginate paste has a good protective effect on colloid.

　　Formulation of sodium alginate original paste:

　　Warm water (40 ~ 50℃) 80 kg

　　0.5～1kg of sodium hexametaphosphate

　　0.2-0.5 kg of soda ash

　　6-8 kg sodium alginate

　　Formaldehyde (40%) 40%)0～100ml

　　Water xkg

　　The alginate paste produced in China is the product of esterification of alginic acid with epichlorohydrin, which improves its stability to acid, metal ions and reducing agent, and improves its screen permeability, so it is suitable for screen printing.