Glue, formaldehyde-modified product

Plasticized sulfur is a hot-melt adhesive and fulfills more of these requirements than any presently available, commercial glue. However, modified sulfur cannot be applied with present production equipment, and sulfur lacks many important, frequently required qualifications, among them fire resistance and resistance to heat. Thus, substantially more work would be necessary to make elemental sulfur a viable commercial bulk glue. However, we found that elemental sulfur can be polymerized in situ with formaldehyde resins (5,33), and this yields bonds which have good mechanical properties, moisture resistance, and promising high-temperature behavior. Such glues can be handled with presently available equipment and presently common process conditions (35,36). These materials are described separately (33). 

The most common types of adhesives used today in coated products are hide glues, varnishes, urea-formaldehyde, radiation-curable, and resole phenolic resins. Depending on the severity of the applications, the make and size bond formulations are modified to suit the job at hand. Combinations of the above systems are used to achieve special properties which may give certain products economic and performance advantages. 

---