Adhesive raw material process

Borax
Borax is also available in powder and granular forms, with fine-grained borax being the best. Borax comes in two grades based on strength. There are 10 water molecules in 10 moles of borax, which is called grade 10 water borax. There are 5 water molecules in 5 moles of borax, which is called grade 5 water borax. 5 moles of borax is a higher concentration. 0.35 kg of 5 moles of borax is equivalent to 0.454 kg of 10 moles of borax. If the same amount of two types of borax is used incorrectly, the consequences will be serious. If borax is added to an emulsion of raw starch and water and the mixture is heated, the starch will expand rapidly after absorbing water and become more viscous than without borax.
There is a certain limit to the amount of borax added, otherwise it will affect the expansion of starch, and the gelatinized paste will become brittle and appear in a powdery state when dry.
Caustic soda only needs to contain 76% sodium oxide and is commercial grade without additives. It can be used in the form of crumbs, granules or flakes. The composition is equivalent to 98% sodium hydroxide. Caustic soda absorbs moisture from the air which reduces its strength. Therefore, if the packaging barrel is damaged, it should not be used. After opening the lid to collect materials, the lid should be closed tightly immediately.
caustic soda
Caustic soda is a strong alkali that can cause severe burns to the skin in its dry state or when dissolved in water. Wear a face mask and rubber gloves when handling caustic soda, and keep a bottle of vinegar handy for immediate treatment of caustic soda-contaminated skin. Caustic soda will smoke when dissolved in water. Do not inhale the smoke as it is poisonous.
Caustic soda is added to the emulsion of raw starch and water, and the mixture is heated to reduce the temperature at which starch swells and gelatinizes. According to this characteristic, the amount of caustic soda added can be used to precisely control the temperature of starch expansion and gelatinization. However, adding too much will cause the gelatinized particles to split, reduce the viscosity, and cause the raw starch in the paste to gelatinize in advance.
formaldehyde
Formaldehyde is in the state of 37% aqueous solution and is measured according to the volume or wet weight specified in the formula. Formaldehyde is commonly used in adhesives for corrosion protection. It is used as a chemical cross-linking agent in some waterproof adhesive formulations. You must wear protective equipment when handling formaldehyde, because formaldehyde is a strong irritant to the eyes and skin, so inhalation should be avoided.
water resistant adhesive
The difference between water-resistant adhesives and ordinary adhesives is that they usually contain more raw starch, less caustic soda, and no or very little borax. Of course, water-resistant adhesives add a certain amount of waterproofing agent. There are many waterproofing agents that can be used, all of which are water-soluble resins. After this type of resin is chemically cross-linked with formaldehyde, it will become an adhesive that is insoluble in water and has certain water resistance when heated on the paste line.
Most water-resistant adhesives have a limited lifespan. Some gradually thicken over time, even under stirring conditions. Some machines have good operating performance, but their water resistance is greatly reduced. Therefore, the adhesive must be used as soon as possible after it is prepared.