Physical and chemical properties of shellac: international number: 904 China number: 14.00 1 Chinese and English name of shellac, molecular formula of shellac of C60H90O5, molecular weight 964-100, temperature coefficient 20-40. 2 10 magnetic susceptibility -0.30× 10-6 adhesion (kg /cm2) is 448 for steel, 448 for optical glass surface 896, 448 for elastic material and 65-70℃ for copper 462. It can be processed to 80℃ melting point 75-80℃ acid value 65-75 saponification value 220-230 density g/cm31.143-1.207. The best solvents for soluble shellac paint chips are lower alcohols containing hydroxyl groups, such as methanol and ethanol, including lactate and ethylene glycol alkyl ether. Insoluble in ethylene glycol and glycerol, soluble in alkaline solution and ammonia water, soluble in lower carboxylic acids such as formic acid and acetic acid, insoluble in aqueous solutions of fats, aromatic hydrocarbons and their halogen derivatives, carbon tetrachloride, water and sulfur dioxide.

Viscosity of the solution The lac solution is dispersed in a dilute solution in molecular form, but in a concentrated solution, the resin is solvated, showing a large viscosity. The viscosity of shellac paint tablets dissolved in two solvents is almost half lower than that dissolved in ethanol alone. For example, the following shellac flakes dissolved in two solvents can obtain a low viscosity solution:

Methanol+Propanol 75: 25

Ethanol+ethyl ethanol 60: 40

Ethanol+acetone 60: 40

As long as the concentration is lower than 20%, shellac will not form colloidal solution. When the concentration exceeds above, the concentration of the solution will rise sharply, and the viscosity will increase with the increase of temperature.

During the storage and transportation of aged shellac paint chips, the aggregation of free groups leads to larger and larger molecules, poor fluidity, shorter thermal life, higher melting point, increased ethanol insolubles, and finally loss of alcohol solubility and use value. Therefore, in the process of storage and transportation, the higher the temperature, the higher the humidity and the faster the aging of the collection. In order to prevent the shellac from aging and deterioration, it should be stored in a low temperature, dry, ventilated and sun-proof place, and avoid excessive temperature and humidity, ventilation and sun-proof during transportation.

Safe shellac resin can be degraded in natural environment. Discharge into the water will increase the aerobic capacity of the water body, make the water body eutrophic, and make the water body appear red in the senses. At present, according to the discharge situation of shellac waste in China, it is suggested that it should be discharged into sludge drying field, filtered by sand and discharged into sewage treatment station after reaching the standard.

Characteristics of shellac resin: excellent moisture resistance, corrosion resistance, rust resistance, oil resistance, electrical insulation and thermoplasticity.

Application of shellac paint chip

Because the main component of shellac paint sheet is shellac resin, it has strong adhesion to smooth surfaces such as glass, metal and mica. Its alcohol solution or alkali solution can well adhere to the surfaces of various objects, forming a smooth, bright and durable paint film, which is non-toxic, so it can be widely used in food, medicine, military industry, electricity, ink, leather, metallurgy, machinery, wood, rubber and other industries.

Lac paint flake in wood industry is simple, easy to use, strong adhesion, fast drying, smooth, hard, transparent, elastic and even in luster, and has a good isolation or sealing effect on wood exudates, stupid amine colorants and asphalt. It has long been widely used in the wood industry. Especially in recent years, due to the toxicity of formaldehyde finishing agent to human body. Many high-grade wood products and decoration are converted to shellac paint.

The food industry is used to film fresh fruits, which can form a bright film, prolong the shelf life of fruits and improve their commodity value. Used for coating candy and cakes to improve brightness and prevent moisture regain, used for coating the inner wall of metal cans to prevent food from contacting with metal.

A bright protective finishing agent for leather industry is characterized by fast drying and strong filling ability, and can be firmly attached to leather to make it softer and more elastic. And presents a gorgeous luster.

The military industry is mainly used as a retarder for the mixture of coating agent, insulating material and gunpowder. It is also used to manufacture military equipment against ultraviolet rays and radiation.

The electrical industry produces insulating cardboard, laminated mica board, ground electrical insulator, insulating paint, light bulb, fluorescent lamp and vacuum tube solder paste.

Rubber industry is mainly used as the surface coating or filler of rubber products. It can improve the luster of rubber products and improve their wear resistance, oil resistance, acid resistance, water resistance and insulation. Slow down the aging process, prolong the service life and improve the physical, mechanical and properties of rubber, such as tensile strength, tensile strength and tear resistance.

In addition to manufacturing insulating paper and industrial wrapping paper, the paper industry is also used as decorative and protective finishing agent for coated paper, food wrapping paper and lampshade paper.

Other medical equipment, matches, toothpicks, buckets, hats, mirrors, sporting goods, sculptures, jewelry processing adhesives.