The environmental problems of adhesives are mainly environmental pollution and human health hazards, which are due to harmful substances in adhesives, such as volatile organic compounds, toxic curing agents, plasticizers, thinners, and other additives, harmful fillers And so on.
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There are many volatile organic compounds (VOC) in adhesives, such as organic solvents in solvent-based adhesives ; free formaldehyde in trialdehyde glues (phenolic, urea-formaldehyde, melamine formaldehyde) ; these volatile substances are discharged into the atmosphere, The harm is great, and some of them undergo photochemical action to produce ozone . The ozone in the lower space pollutes the atmosphere and affects the growth of organisms and human health. Some halogenated hydrocarbon solvents are substances that destroy the ozone layer of the atmosphere. Some aromatic hydrocarbon solvents are very toxic and even carcinogenic. Methyl methacrylate , sulfur dioxide , ethylamine and other strong irritating odors can be described as the poison of pollution and worsen the atmospheric environment.
Hardener plasticizer
Aromatic amine curing agents are very toxic, and some can also cause bladder cancer, such as m-phenylenediamine . The plasticizer tricresol phosphate is extremely toxic. It is especially harmful to the liver and kidneys, and may even cause cancer. In addition to the adhesives used in food contact, the general use of DBP and DOP in adhesives is not a big problem, but it should also be noted.
Toxic filler
There are many types of fillers used in adhesives, and some of them can also cause toxicity. For example, asbestos powder fiber is very slender, which pollutes the environment seriously and is a powerful carcinogen. Dust flies with the wind, enters the human body through the respiratory tract and pores, and can accumulate in the lungs, leading to lung cancer, bronchial cancer , mesothelioma, etc. The incubation period of diseases caused by asbestos is quite long, even up to 40 years. Japan calls asbestos a "quiet time bomb". Long-term inhalation of quartz powder can cause silicosis. Fillers or pigments containing toxic heavy metals (lead, chromium, cadmium) are also very harmful to the human body.
Toxic and harmful additives
When the base resin (or rubber) used in the adhesive is determined, the formulation and application performance of the adhesive depends to a large extent on the adjustment and modification effects of the additives used, and attention must be paid to the toxicity of some additives. Antioxidant D has been confirmed It is carcinogenic, and BHT is suspected of causing cancer. MOCA, azobisisobutyronitrile (AIBN), and dibutyltin dilaurate all have greater toxicity.
Pollutants and hazards
Many adhesives have varying degrees of potential environmental pollution. Only by clearly understanding the types and hazards of the pollutants can we try to eliminate and prevent them. The harmful substances in the adhesive are mainly benzene, toluene, formaldehyde, methanol, styrene, chloroform , carbon tetrachloride , 1,2- dichloroethane , toluene diisocyanate , m-phenylenediamine, tricresol phosphate, Ethylenediamine, dimethylaniline , antioxidant D, coal tar, asbestos powder, quartz powder, etc. A brief analysis of the harmful substances in the specific types of adhesives is as follows.
Epoxy resin adhesive
Epoxy resin adhesive is an important type of engineering adhesive. It has good bonding properties to various metals and most non-metal materials .
Harmful substances in epoxy resin adhesives are curing agents such as aromatic amine, ethylenediamine, dimethylpropylamine, maleic anhydride, dodecenyl succinic anhydride; plasticizers such as tricresyl phosphate, DBP, DOP, etc.; 501 690, butadiene diepoxy, epoxidized styrene, vinyl cyclohexene diepoxy (YJ-132), coal tar and other diluents; quartz powder, asbestos powder, chromium trioxide , zinc chromate, Fillers such as beryllium oxide. 690 thinner has a strong allergic and poisoning effect on the skin. Butadiene diepoxy is the most toxic. Vinyl cyclohexene diepoxy is irritating to the skin and can also cause sarcoma in white mice. Coal tar is harmful to the environment and human body. In 1998, it was discovered that some quartz powder factories in Guangzhou, workers who had worked for two years had silicosis, and some of them felt that their physical strength was greatly reduced after only half a year. According to reports, the incubation period of silicosis is 15 years.
Phenolic resin adhesive
Free phenol and formaldehyde in phenolic resin adhesives can pollute the environment and endanger health. Phenol vapor is irritating and can cause poisoning when in contact with the skin. It can damage the kidneys after inhalation. The maximum allowable concentration in the air is 5ppm. The suffocating odor has a strong stimulating effect on the eyes and nose. Causes tears and allergies. Inhalation of formaldehyde vapor can cause nausea, rhinitis, bronchitis and conjunctivitis, and skin contact can cause allergies or dermatitis. The US Environmental Protection Agency announced in 1987 that formaldehyde may have carcinogenic effects on the human body [6, 7]. The maximum allowable concentration in the air is 5mg?m-3.
Polyurethane adhesive
Harmful substances in polyurethane adhesives are isocyanate , MOCA, dibutyltin dilaurate. The solvent chlorobenzene in polyisocyanate adhesives is very toxic. Free toluene diisocyanate (TDI) has a strong irritation to the skin, eyes, and mucous membranes. The maximum allowable concentration in the air is 0.14 mg?m-3. The carcinogenicity of MOCA is still controversial.
α- cyanoacrylate adhesive
Polymerization inhibitor of α-cyanoacrylate adhesive: sulfur dioxide (S02). It has a pungent odor and can cause air pollution. It has a strong stimulating effect on the eyes and respiratory tract. Large amounts of inhalation can cause pulmonary edema, laryngeal edema, vocal cord spasm and suffocation.
Anaerobic adhesive
The curing accelerators N,N-dimethyl aniline and dimethyl p-methyl aniline used in anaerobic adhesives have certain carcinogenicity.
Modified Acrylic Fast-curing Structural Adhesive
Modified acrylate fast-curing structural adhesive is also called SGA adhesive. Methyl methacrylate (MMA) is commonly used as the active monomer. Although it is minimally toxic, it has a great odor, unbearable, pollutes the environment, and is in the redox system. Reducing agents such as N,N-dimethylaniline, N,N-diethylaniline, N,N-dimethyl-p-toluidine, N,N-diisopropyl p-toluidine and other aromatic amines , Can cause bladder cancer.
Unsaturated polyester adhesive
Styrene, a commonly used cross-linking monomer for unsaturated polyester adhesives, has a pungent odor, and has been considered to be less toxic than benzene in the past. In 1996, the International Cancer Research Group of the World Health Organization (WHO) conducted an in-depth study of styrene and concluded that styrene does have carcinogenic effects [2]. Breathing styrene gas can cause people to produce lymphoma, hematopoietic system tumors and non-tumor diseases, especially diseases of the central nervous system , the latter being latent. With the duration of breathing styrene gas and the accumulation of doses, the danger is even greater. The volatilization of styrene has caused environmental pollution and health hazards. As an accelerator of unsaturated polyester adhesives , N,N-dimethylaniline and N,N- diethylaniline are carcinogenic, and decompose aniline gas when heated. People who are exposed to aniline suffer from bladder cancer. 30 times that of the average person.
Neoprene adhesive
Neoprene adhesives are mainly solvent-based adhesives, including ordinary neoprene adhesives and grafted neoprene adhesives, including benzene, toluene, mixed benzene , dichloroethane, chloroform, trichloroethylene , carbon tetrachloride, n-hexane, Solvent gasoline , graft monomer MMA, antioxidant D, etc. all pollute the environment and are toxic to the human body. Benzene vapor has an aromatic smell, but it is highly toxic to humans. It can be poisoned by inhalation and absorption through the skin, causing dizziness, headache, fatigue, and death due to respiratory spasm in severe cases. Benzene is classified as a carcinogen, and long-term exposure may cause bladder cancer. The maximum allowable concentration in the air is 40mg?m-3. Toluene is more toxic, irritating to the skin and mucous membranes, and has a stronger effect on the nervous system than benzene. Long-term exposure may cause bladder cancer, but toluene can be oxidized to benzoic acid, and glycine to generate hippuric acid, which can be extracted from urine. It is discharged, so it is not toxic to the blood. The maximum allowable concentration in the air is 100mg?m-3.
1,2-Dichloroethane is highly toxic, irritating to the skin and mucous membranes, and can cause coma. The US Environmental Protection Agency classifies it as a carcinogen, and the maximum allowable concentration in the air is 25mg?m-3. Trichloromethane is narcotic and is considered a carcinogen . It reacts to form highly toxic phosgene in sunlight, oxygen and moisture, especially when it comes in contact with iron. The maximum allowable concentration in the air is 240mg? m-3. The solution of carbon tetrachloride dissolved in neoprene is very viscous , easy to volatilize, and does not burn, but it is extremely toxic, has strong irritation and anesthesia, and the maximum allowable concentration in the air is 25rng?m-3. In addition to the health hazards, chlorinated solvents are also substances that destroy the ozone layer of the atmosphere. In the past, n-hexane was mistakenly regarded as a non-toxic solvent. In fact, it has certain toxicity. Inhalation of vapor can stimulate the mucous membrane of the upper respiratory tract. Inhalation of high concentration can numb the nerves and cause poisoning. In severe cases, it can cause paralysis or even paralysis, about 0.5. -1 year. In 1997, severe poisoning and paralysis occurred in Guangdong. Solvent gasoline has an anesthetic effect on the central nervous system of the human body. In mild cases, anesthesia symptoms such as dizziness, headache, fatigue, limb tremor, nervousness, etc. may appear; in severe cases, coma, convulsions, convulsions, weak pulse, lower blood pressure, changes in body temperature, etc. may appear quickly Symptoms and even death due to respiratory anesthesia. The maximum allowable concentration in the air is 0.02% (V01).
4115 construction glue
4115 construction glue is made of polyvinyl acetate, talc powder, light calcium carbonate , asbestos powder, etc. which are polymerized by vinyl acetate in methanol . Methanol has a significant accumulation effect in the human body, and slowly oxidizes to formaldehyde and formic acid, destroying the intracellular oxidation, and severely poisoned patients can also develop cerebral edema. Alcohol has a serious poisoning effect on the central nervous system, damages the optic nerve and retina, first has blurred vision, and then causes blindness. A normal person drinking 4-10g of pure methanol at a time can cause serious poisoning, drinking 7-8g can cause blindness, drinking 30-100g will cause death.
107 glue
107 glue is a water-soluble adhesive prepared by condensation reaction of polyvinyl alcohol aqueous solution and formaldehyde solution under the catalysis of hydrochloric acid and then neutralized.
harmful.
Solvent-based pressure sensitive adhesive
Rubber-based or acrylic solvent pressure-sensitive adhesives use a large amount of toluene and other volatile organic solvents . The solvent volatilizes and the smell is overflowing, which not only pollutes the surrounding environment, but also harms human health.
Solvent-based paper-plastic composite adhesive
Most of the laminating adhesives used are organic solvent type, with toluene, ethyl acetate , solvent gasoline, etc. as mixed solvents , accounting for more than 60% of the total glue volume. These organic solvents volatilize into the atmosphere, seriously polluting the environment and harming the environment. healthy.
PVC plastisol
PVC plastisols is a PVC paste resin through a phthalate -based plasticizer prepared. Vinyl chloride monomer carcinogens remain in the paste resin, and phthalate plasticizers have low toxicity to humans and teratogenicity to mice.
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