Toxicity and safe operation of epoxy curing agent

Foreign scientists believe that energy and curing agent toxicity are two unavoidable problems in the application of epoxy resin Therefore, the study on the toxicity of curing agent is very important The focus of the study is on the test of the toxicological data of curing agent, with LD50 as the main target The so-called half lethal dose is the 50% lethal dose of the drug to the animal group (such as a group of mice), expressed in mg / kg units This is the acute toxicity data of the curing agent In addition, there are data of subacute test (90 days to get results) and chronic toxicity test (2 years to get results) 1 The toxic effect of curing agent the physical and chemical properties of curing agent have a great influence on the toxicity For example, if the curing agent is liquid or solid, its toxic effect is not the same The solid is easy to attach to the skin, while the liquid has the existence of vapor pressure Generally speaking, if the chemical activity of the curing agent is large, its biomass activity is also strong, and it is easy to cause toxicity, which seems to be a rule The toxicity of curing agent is shown in the following aspects 1 Acute toxicity Generally, LD50 is used The toxicity of amine curing agent is relatively strong The LD50 value of most organic polyamines was about 1000-12000ug / g of vapor concentration and 4-6h of exposure time Primary amines and secondary amines are more irritating than tertiary amines, and aromatic amines are more toxic than aliphatic amines For example, the toxicity of m-phenylenediamine is 10 times higher than that of diethylenetriamine Pyridine and piperazine can cause liver and kidney damage, and have a greater systemic toxicity Anhydrides tend to cause dermatitis, but oral toxicity is relatively small 2 It can stimulate the skin and mucous membrane The toxicity of curing agent is more important in the stimulation of skin and mucous membrane Because amine is an organic base, soluble in water and fat, it can also be dissolved and soaked in skin fat, causing dermatitis Long term stimulation may lead to generalized strong skin inflammation, spot like erythema, blister formation, cracking and even flake peeling, resulting in tissue necrosis Hine et al Have carried out detailed research work, and the results are shown in table 3-52 Because amines are volatile, their vapors can cause conjunctivitis, tears and corneal edema In the high concentration range or long-term contact under high concentration, it will also have an obvious stimulating effect on the respiratory tract, causing tracheitis and bronchitis Anhydrides are less irritating to the skin, but their dust can stimulate the mucous membrane of eyes, nose, throat and other respiratory tract, which can cause bronchitis 3 Anaphylaxis of curing agent The so-called allergy, that is, once a compound acts on the skin of the human body, an allergic body is formed In the next or subsequent repeated contact, dermatitis will also occur not because of the degree of contact In this case, the work of contacting the allergic compound should be interrupted The occurrence of anaphylaxis is complex, and we are continuing to develop pills such as Ciba company to use pudding test to study animals The American Plastics Industry Association (SPI) has introduced its own standards 4 Other toxic effects of curing agent In addition to the damage of aromatic amines and heterocyclic amines to the internal organs, benzenearomatic amines are carcinogenic and have been banned from production and use M-phenylenediamine and diaminodiphenylsulfone have been proved to be carcinogenic by many toxicologists, and their previous views have been denied 2 Safe operation of using curing agent 1 Replacing toxic curing agent with less toxic one 2 Improve the operation environment, consciously separate the operation area from the non operation area, automate and seal as much as possible, install ventilation facilities, etc 3 Strengthen labor protection, adopt protective gloves, clothing and other methods, and try to avoid the contact between curing agent and skin 4 Clean the operation site in time and keep it clean 5 Wash the exposed skin such as hands and face in time If the organs such as eyes and throat are damaged, ask a doctor for treatment 3 Toxicity of other related compounds 1 Epichlorohydrin, the raw material of epoxy resin (mainly discusses bisphenol a type): due to the existence of epoxy group and chlorine substituent, it is quite toxic, and can kill mice in 240 UG / G environment for 4 hours According to gage, the maximum allowable MAC is 5ug / g, which is also very irritating to eyes, nose and pharynx According to bisphenol A: Borman, LD50 is 2.4g/kg, so the industrial harm is very small 2 The toxicity of epon815, 820, 828, 1001, 1007 and resorcinol glycidyl ethers of bisphenol A epoxy resin has been proved to be very low, usually LD50 value is in the range of 10-30g / kg Hine et al Believe that the toxicity of the diluent mono glycidyl ether is mainly manifested in the stimulation of skin, and the oral LD50 value of toxicity is also very low 3 Toxicity of the cured epoxy resin: the cured common epoxy resin (50% - 70% in dioctyl phthalate) was mixed in the food (about 10%) The rats were given orally for 26 weeks, only resulting in weight loss and no internal disease However, after 26 weeks of feeding, the death rate of mice increased Therefore, it can be considered that the cured epoxy resin (bisphenol a type) is nontoxic However, if the curing is not complete, it is another matter