Epoxy curing agent is a chemical reaction with epoxy resin to form a network of three-dimensional polymer, the composite material enveloped in the mesh body. Makes linear resin an additive for tough, bulk solids.
effect:
The physical and chemical properties of the curing agent have a great influence on the toxicity. For example, if the curing agent is a liquid or a solid, the toxic effects are not the same. The solid state is easy to attach to the skin, while the liquid state has a vapor pressure. In general, when the curing agent has a large chemical activity, its biomass activity is also strong and can easily cause poison. It seems to be a rule. Curing agent toxicity in the following aspects.
Acute toxicity.
LD50 is generally used. Amine curing agents are relatively toxic. The LD50 value of most organic polyamines on rat respiratory tract stimuli is approximately 1000-12,000 ug/g vapor concentration and exposure time is 4-6 h. Primary amines and secondary amines are more irritating than tertiary amines, and aromatic amines are more toxic than fatty amines. For example, m-phenylenediamine is 10 times more toxic than diethylenetriamine. Pyridine and piperazine can cause liver and kidney damage, and have a greater systemic toxicity. Anhydride curing agents are prone to cause dermatitis and oral toxicity is relatively small.
Stimulation of skin and mucous membranes.
The poisoning of curing agents, more importantly, is reflected in the irritation to the skin and mucous membranes. Because amines are organic bases that dissolve in water and fat, they also dissolve and soak in the skin's fat, causing dermatitis. Prolonged stimulation can easily lead to generalized cutaneous inflammation, punctate erythema, blistering, cracking, and even exfoliation, resulting in tissue necrosis. Hine et al. conducted detailed research work. The results are shown in Table 3-52. Due to the greater volatility of amines, their vapor stimulation of the eyes can cause conjunctivitis, tearing, and corneal edema. Long-term exposure at high concentrations or at higher concentrations can also have significant irritating effects on the respiratory tract and cause bronchitis and bronchitis. Acid anhydrides are less irritating to the skin, but their dust is quite irritating to the mucous membranes of the eyes and the respiratory tract such as the nose and throat, and can cause bronchitis.
Allergic effects of curing agents.
The so-called allergies, that is, a compound once formed on the human skin, the formation of allergies, in the next or subsequent repeated exposure, not because of the degree of contact, dermatitis will occur. After this happens, the exposure to the allergy compound should be interrupted. The occurrence of allergic reactions is more complicated and pudding tests are used to study animals. The American Plastics Industry Association (SPI) has introduced its own standards.
Other poisoning effects of curing agents.
In addition to visceral damage caused by aromatic amines and heterocyclic amine curing agents, biphenyl aromatic amines are carcinogenic and have been banned from production and use. M-phenylenediamine and diaminodiphenyl sulfone have been proven by many toxicologists to be non-carcinogenic, and they reject previous views.
operating:
Use a low-toxicity hardener to replace the most toxic ones.
Improve the operating environment, consciously delineate the operating area from the non-operating area, automate and seal as much as possible, install ventilation facilities, etc.
Strengthen labor protection, use protective gloves, clothing and other methods, try to avoid contact with skin and curing agent.
The operation place is cleaned in time and maintains hygiene.
Wash hands, face and other exposed skin in time. If eyes, throat, and other organs are infringed, you should ask your doctor for treatment.
other:
Epoxy resin (mainly discussed bisphenol A type) raw materials
Epichlorohydrin: Due to the presence of epoxy groups and chlorine substituents, the toxicity is quite high. In the environment of 240ug/g for 4 hours, mice can be killed. Gage proposed that the maximum allowable value of MAC is 5ug/g, and the other eye, nose, and throat irritation is also great; Bisphenol A: Borman proposed LD50 of 2.4g/kg, so that the industrial harmfulness is considered to be very small.
The toxicity of the bisphenol A type epoxy resins Epon 815, 820, 828, 1001, 1007, and resorcinol glycidyl ether compounds was confirmed to be very low, and the LD50 values ​​were generally in the range of 10 to 30 g/kg. Hine et al. believe that the toxicity of the diluent monoglycidyl ether compound is mainly manifested in the skin irritation, and the oral toxicity LD50 value is also very low.
Epoxy resin cured material toxicity
The cured ordinary epoxy resin (50% to 70% in dioctyl phthalate) was mixed in the food (about 10%), and the mice were given orally for 26 weeks and only caused weight loss. , did not cause internal symptoms. The uncured Epon 828 resin was mixed in the food (about 5%) and the mice died after 26 weeks of feeding. Therefore, it can be considered that the cured epoxy resin (bisphenol A type) is non-toxic. However, if the curing is not complete, it is another matter.
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