Characteristics and uses of CA plastics
Because of its characteristics and quality of different varieties are different, generally use as general plastics, in addition to avoid the use of related in food packaging, medical devices and health fields, the other is used. For example, car interior and exterior shell, household appliances and other daily necessities, mainly low price.
A chemically modified natural polymer obtained by esterification of hydroxyl groups in cellulose molecules with acetic acid. Its performance depends on the degree of acetylation.
Cellulose acetate (Cellulose Acetate, hereinafter referred to as CA, or cellulose acetate, cellulose acetate) was first prepared in 1865 and is the acetate of cellulose. CA used for photographic film base, is a component of some adhesive for synthetic fiber.
Commercially available products can be divided into general cellulose acetate (acetyl - 37% - 40%). Plasticizers are often added as injection molded parts, such as toothbrushes, brushes, etc.. Cellulose acetate with a high acetyl content (40% to 42% acetyl), white, granular, powdery or cotton solid. The light stability, not easy to burn, in dilute acid, gasoline, mineral oil and vegetable oil in stability, swelling in chloroform, insoluble in acetone, methyl acetate, can dilute alkali erosion, has advantages of toughness, transparency, good gloss, good melt fluidity, easy molding. Dichloromethane homogeneous method using refined cotton linter and acetic acid with acetyl sulfate as catalyst, esterification, hydrolysis in the presence of dichloromethane solvent, can be combined with cellulose acetate acetic acid content in 60% + 0.5% range. The traditional method is to use dry cotton, acetic acid in the presence of catalyst activation, sulfuric acid, acetic acid and acetic anhydride with mixture of acetylation, then adding dilute acetic acid hydrolysis to belong to the degree of substitution, and catalyst, precipitation, acid washing, rice drying. After partial hydrolysis, cellulose acetate is called two, and the degree of esterification is 220~270. Without hydrolysis, that is, the degree of esterification, the gamma value of 300, said three cellulose acetate. Two cellulose acetate plastic handle, can do all kinds of tools of computer and typewriter alphanumeric keys, phone chassis, car steering wheel, textile equipment parts, radio switch and insulation, pen, spectacle frame and lens, toys, daily necessities, but also do desalination membranes. Three cellulose acetate, high melting point, can only match into solution processing, used as a movie film, X film, light film, electromagnetic diaphragm insulating tape, transparent container, the silver zinc battery.
