Environmental Problems of Adhesives and Countermeasures (Part 2)

Solventless

Solvent-free means that the adhesive contains no solvent and no solvent will volatilize to the atmosphere, causing no pollution and harm.

Most epoxy adhesives, anaerobic adhesives, cyanoacrylate adhesives, aerobic modified acrylate structural adhesives, solvent-free polyurethane adhesives, and light-curable adhesives are all solvent-free types.

Solidification

Solidification of adhesives is used in the form of solids, such as hot melt adhesives, hot melt pressure sensitive adhesives, water soluble powdered adhesives, reactive adhesives, office glue sticks, etc., with no volatiles during coating and bonding processes. Released, there is no environmental pollution.

Foreign praise for the use of powdered plastic, with stable performance, no environmental pollution and other advantages. U.S. CP Adhesive Co., Ltd. produced a urea-formaldehyde resin powder, which itself contains a curing agent and filler, is odorless, non-polluting, and non-toxic, and is used as an excellent general-purpose wood adhesive. A high-strength and high-quality powdery adhesive has emerged in the country—Bangjia Super Strength Powder (4). It is mixed with water and becomes a polymer dispersion. It has outstanding adhesion, water resistance, and aging resistance. The United States produced a wide range of epoxy glue sticks, emergency repair, plugging is very convenient.

Low toxicity

Solvent adhesives have fast drying speed and good water resistance. Although they are highly polluting and toxic, they are not completely replaced by water-based adhesives. They can use low-toxicity or non-toxic solvents such as cyclohexane, ethyl acetate and butanone. 1,1-Dichloroethane, dimethyl carbonate, etc., made of non-toxic or low-toxic solvent-based adhesives, the domestic market has emerged no "triphenyl" polyurethane adhesive for shoes, shoes without "triphenyl" Branch neoprene adhesive, no "triphenyl" SBS-type special effects adhesive. It is worth mentioning that dimethyl carbonate (DMC) is a new and excellent low toxicity solvent. Japan has used DMC as the main solvent for the preparation of solvent-based adhesives. At present, large-scale production has been established in China.

Adopt advanced clean production new technology

Clean production of new technology can achieve the unity of economic benefits and environmental benefits, and production of environmentally friendly adhesives.

Discard use of large methyl methacrylate and switch to higher boiling monomers. Production of modified acrylic fast-setting structural adhesives.

No toxic materials such as formaldehyde, chlorinated solvents, aromatic hydrocarbon solvents, and toxic heavy metal fillers are used during the formulation and production of adhesives.

The production is carried out under non-toxic and harmless conditions, such as the production of a modified amine curing agent using paraformaldehyde instead of a formaldehyde solution.

By increasing the amount of hydrochloric acid and lowering the pH, the polyvinyl formal reaction can be more complete, the free formaldehyde content can be reduced to below 0.2%, and the formaldehyde odor can hardly be detected.

The addition of formaldehyde trapping agents, such as starch, polyvinyl alcohol, melamine, etc., can significantly reduce the free formaldehyde content of the urea-formaldehyde resin adhesive. Among them, oxidized starch is more effective than ordinary starch, and it can make free formaldehyde content <0.1%.

Improve environmental protection standards and regulations

Solve the environmental problems of adhesives must also have legal protection, develop environmental quality standards for adhesives, strengthen supervision, strict management, non-compliance is not allowed production, not allowed to sell, limit the production and use of "triphenyl" glue, limit "trialdehyde The free formaldehyde content of glue limits the emission of harmful gases and limits the use of chlorinated solvents.

Conclusion

Adhesives belong to the new field of fine chemical products. At the same time, rapid development has brought about environmental pollution and harm to health problems. It has aroused widespread concern, must pay attention to the protection of the environment, and must not exchange for the economy at the expense of the environment and waste of resources. The momentary increase.

Adhesives used in aromatic solvents, chlorinated solvents, aromatic amine curing agents, styrene, vinyl chloride, formaldehyde, methanol, asbestos powder, etc. will cause environmental pollution and human hazards. In order to prevent pollution, protect the environment, reduce hazards, and promote development, adhesive production and use must all increase environmental awareness and develop environmentally friendly green adhesives that are water-based, solvent-free, solid, and low-toxic. This is the direction.

Source: Packaging News