Urea-formaldehyde plastic is commonly known as "electric jade". It is a plastic made of urea-formaldehyde resin as the basic component. It is a thermosetting plastic. There are mainly four types of urea-formaldehyde molding plastics, urea-formaldehyde foam plastics, cast urea-formaldehyde plastics and laminated urea-formaldehyde plastic sheets. Its surface is smooth, hard, bright in color, arc-resistant, flame-resistant, and has good electrical insulation properties. It is widely used in the manufacture of daily electrical appliances, mechanical parts, accessories for electrical and instrumentation industries, various handles and decorations, cultural and educational supplies, various buttons and bottle caps, etc. Urea-formaldehyde foam plastics are mainly used to manufacture sound insulation and heat insulation materials for vehicles, ships, buildings, etc.

Chemical properties

Urea-formaldehyde plastic is a thermosetting plastic developed in 1930. It is a hard translucent material with coloring properties and is widely used in bottle caps and cosmetic boxes. Urea-formaldehyde plastic products are more expensive than some thermoplastics. However, heat resistance and other excellent properties can compensate for the price factor. Due to its translucency, it produces a light and dark color similar to milky glass, so it can produce a variety of beautiful colors. Urea-formaldehyde plastic is short for urea-formaldehyde plastic, which reflects the two main raw materials used in the manufacture of this plastic. When the two substances react in the presence of an alkaline catalyst, NH2-CO-NH2+HCHO, a monomer, NH2-CO-NH-CH2OH, is formed. When it is combined with a potential catalyst and heated in a mold, an acid is produced to promote polymerization.

Characteristics

Urea-formaldehyde plastic is suitable for a variety of colors. It can be colored in various shades such as pink and lavender, but the color grades of yellow and orange are relatively rare. It is difficult to have a good color contrast, and these colors will fade after a period of time. In the past, the U.S. Department of Commerce has set standards for the color of urea-formaldehyde as the standard for molded urea-formaldehyde plastics, which are known as "Mapp colors". Urea-formaldehyde is a hard, brittle, odorless and tasteless material. It has a good gloss and a pleasant translucency. It does not generate static electricity and is not easy to attract dust.

Performance

Compared with phenolic plastics, urea-formaldehyde plastics are much more expensive, but the color range is much wider. If appearance is important, then urea-formaldehyde must be chosen. Because urea-formaldehyde is a thermosetting plastic, it can withstand high temperatures without softening, but it will carbonize at around 390буF. Under very humid conditions, it will absorb water, but this is not a very serious defect for it. Urea-formaldehyde does not react with any organic solvents, but it is not resistant to alkalis and strong acids, and has excellent resistance to any oils and greases. Although urea-formaldehyde can withstand high temperatures, it cannot be sterilized by steam. In addition to the shrinkage it will produce in the mold, it will also shrink by 0.1003 inches/inch.

Price

Because urea-formaldehyde is a thermosetting resin, its processing is limited to die casting, injection molding or extrusion molding. Cold spots in the mold will cause warping, and too much water in the resin will also cause warping. Other disadvantages are streaks at the weld, bubbles due to insufficient ripening, over-ripening or gas inclusions, and "orange peel" on the surface if the fluidity in the mold is poor. Among thermosetting plastics, urea formaldehyde is priced in the middle range, at 65 cents per pound and 3.5 cents per cubic inch per unit volume. The price is significantly higher than phenolic formaldehyde but not as expensive as melamine. Its price is equivalent to that of acrylic resins in thermoplastics.

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