Toxicity problems and safe operation of epoxy curing agents

foreign scientists believe that energy problems and curing agent toxicity are two unavoidable problems in epoxy resin applicationsTherefore, the study of the toxicity of curing agent is very important, the research focus on the testing of toxicology data of curing agent, which takes the semi-lethal LD50 index as the main targetThe so-called semi-lethal amount, is the animal group (such as a group of mice) 50% of the lethal drug volume, with mg/kg units to expressThis is the acute toxicity data that indicates the curing agentIn addition, data are available for subacute trials (results required from 90 days) and chronic toxicity trials (results requiring 2a), the toxic effect of curing agent curing agent's physical and chemical properties, the impact on toxicity is very largeFor example, the curing agent is liquid or solid, its toxic effect is not the same, solid state is easy to attach to the skin, and liquid has the presence of vapor pressureIn general, the chemical activity of curing agent is large, then its biomass activity is also strong, easy to cause poison, it seems to become the lawThe toxicity of curing agents manifests itself in the following aspects1, acute toxicityLD50 is generally usedThe toxicity of amine curing agent is relatively strongMost of the LD50 values of organodoamine on the lethal cause of respiratory stimulation in mice were about 1000 to 12000 ug/g vapor concentrations, with exposure time of 4 to 6hThe irritating properties of buramine and midamine are stronger than that of thamines, and aromatic amine is more toxic than that of amylamineFor example, the toxicity of benzodiazepines is 10 times stronger than that of diethylene triamineRadon and radon can cause liver and kidney damage and have a large systemic toxicityAcid anhydride curing agent is easy to cause dermatitis, and the oral toxicity is relatively small 2, the stimulation of the skin, mucous membranes The toxicity of curing agents is more importantly reflected in the irritation of the skin and mucous membranes Because amines are organic alkalis that dissolve in water and fat, they can also dissolve and permeable in the fat of the skin, causing dermatitis Long-term stimulation, easy to lead to widespread strong skin inflammation, the appearance of spot-shaped erythema, the formation of blisters, cracking and even the formation of flaky peeling, so that tissue necrosis Hine et al have carried out detailed research work, the results of which are shown in Tables 3-52 Because amines are highly volatile, their vapor stimulation of the eyes can cause conjunctivitis, tears and corneal edema Long-term exposure in the high concentration range or at higher concentrations will also have a significant stimulating effect on the respiratory tract, which can cause bronchitis and bronchitis Acid acid is less irritating to the skin, but its dust on the eyes and nose, throat and other respiratory mucosa stimulation is quite strong, can cause bronchitis 3, the allergic effect of curing agent The so-called allergy, that is, once a compound on the human skin, the formation of allergic body, in the next or after repeated contact, not because of the degree of exposure, dermatitis will also occur After this occurs, contact with the allergy compound should be interrupted The occurrence of allergic effects is more complex, and research is continuing to be done by companies such as Ciba using pudding tests to study animals The American Society of Plastics Industry (SPI) has introduced its own standards 4, other toxic effects of curing agents In addition to the damage to the internal organs of aramids and heterocyclic curing agents, biphenyl aromaticamines are carcinogenic and have been banned from production and use Interphaine and diaphnitomynide have been confirmed by many toxicologists to be carcinogenic and have rejected previous views second, the safe operation of the use of curing agent
1, with low toxiccuring agent instead of toxicity 2, improve the operating environment, the operating area and non-operational areas consciously cut apart, as far as possible automation, closure, installation of ventilation facilities and so on 3, strengthen labor protection, the use of protective gloves, clothing and other methods, try to avoid curing agent and skin contact 4, the operation place in a timely manner cleaning, to maintain hygiene 5, timely cleaning of hands, face and other exposed skin, if the eyes, throat and other organs are violated, should be treated by a doctor 3, toxicity of other related compounds
1, epoxy resin (mainly discussed bisphenol A type A) raw material epoxy chloropropane: due to the presence of epoxy- chlorine-substitution base, the toxicity is quite large, in the environment of 240ug/g 4h can kill mice Gage proposes a maximum allowable MAC of 5ug/g, which is also highly irritating to the eye, nose and pharynx; 4g/kg, so considered industrial harmful is very small 2, Bisphenol A epoxy epoxy eponsin Epon815, 820, 828, 1001, 1007, and interphenol-shrinking glycerin ether compounds, the toxicity was found to be very low, usually LD50 value in the range of 10 to 30 g/kg Hine et al believe that the toxicity of the thinner single shrinkgy ether compounds, mainly manifested in the stimulation of the skin, the oral toxicity LD50 value is also very low 3, the toxicity of epoxy curing sin will be cured ordinary epoxy resin (in phthalates, the content of 50% to 70%) mixed in food (about 10%), after mouth to the mice to eat for 26 weeks, only caused weight loss, did not cause internal symptoms The uncured Epon828 resin was mixed with food (about 5%) and the number of mouse deaths increased after 26 weeks of feeding Therefore, it can be considered that the cured complete epoxy resin (Bisphenol A) is non-toxic However, if curing is not complete, it is another matter