Лако-красочные материалы — производство

Since dry and compounded animal glues are used over a wide range of dilutions from 1% or lower to over 50%, no general ratio can be given. Dry glues are generally available in coarse (10 to 30 mesh) or fine (30 mesh and finer) granulation. Powdered glues (100 mesh and finer) are also available for special applications. Compounded glues are available as dry blends, in gelled cake form, or as liquid products.

Dry glues are readily prepared for use. The direct addition of dry glue to hot water in a jacketed, mechanically agitated mixer is recommended for fastest preparation. Thermostatic controls are recommended to hold the glue temperature at 140 to 145° F for use. Alternatively, the dry glue can be soaked in cold water until swollen, then trans­ferred to a jacketed melting tank with agitator, melting, and stirring the glue into solution.

For best results, the dry glue should always be weighed. Water may be measured or weighed. Stainless steel mixing tanks are preferred. Water-jacketed mixers with low — pressure steam injection are recommended for large batches. Electrically heated mixers are usually preferred for small batches. Good agitation is important. Compounded dry blends are prepared in the same manner as dry glues. Cake glues (usually in 5 to 10-lb slabs) are placed in a suitable mixer, diluted as required with water, melted, and held at 140 to 145° F for use. Liquid glues are ready to use as is at room temperature. Cake glues contain modifiers such as corn syrup, sugars, magnesium sulfate (epsom salt), glycerine, sorbitol and other glycols, dextrins, clays and pigments, water-soluble organic solvents, and sur­factants, depending on desired properties, as well as water, preservatives, and odorants.