Coating technology: overview of detection methods of toxic and harmful elements in coating

Core tip: the material civilization of human beings is constantly improving, but the negative impact is growing Many modern industrial production processes and products pose a serious threat to people's health and living environment, so green environmental protection, safety and health have become eternal themes At present, in the production and use of coatings, environmental protection and safety issues are more concerned As a functional material for anti-corrosion protection, coating is widely used in various fields of national economy, such as ship, automobile, machinery manufacturing, construction, etc., almost involving every aspect of people's daily life China in 2009 Paint knowledge | precautions for wall paint color selection Recommended introduction: when painting the wall, the owner sometimes has difficulty in choosing what color of the wall paint to paint In fact, there is no ugly color in the wall paint, only the disharmonious color matching The use of wall color contains the knowledge of health Too strong color will stimulate people's perception, make people have a sense of fidgety, affect people's mental health Grasp the basic principles of wall color and paint a colorful space 1、 Wall paint color selection notice 1 Light color is generally used for the top surface Light colors make people feel light, dark colors make people feel heavy Usually, the treatment of rooms is from top to bottom, from shallow to deep For example, the ceiling and walls of rooms are white and Home of coatings news: the material civilization of human beings is constantly improving, but the negative impact is growing Many modern industrial production processes and products pose a serious threat to people's health and living environment, so green environmental protection, safety and health have become permanent themes At present, in the production and use of coatings, environmental protection and safety issues are more concerned As a functional material for anti-corrosion protection, coating is widely used in various fields of national economy, such as ship, automobile, machinery manufacturing, construction, etc., almost involving every aspect of people's daily life In 2009, China's paint production has leaped to the first place in the world, becoming a real paint production and consumption country With the development of coating application and the improvement of people's awareness of health and environmental protection, more and more attention has been paid to the safety of coatings, among which the impact of toxic and harmful elements on human health has been paid much attention 1 Sources of harmful elements in coatings and harmful elements to human body the harmful elements in coatings mainly come from various raw materials used in the production process, such as various resins, pigments, fillers, additives, solvents, etc., which will bring various elements The toxicity of elements is related to their forms, concentrations and valence states The harmful elements in the coating come into contact with the human body through the use of the coating, or enter the human body through the biological chain after enrichment in the organism, and accumulate in the human body, making people appear different degrees of poisoning For example, lead has a direct toxic effect on specific nerve structures in multiple central and peripheral nervous systems, leading to mental decline, especially in children with learning disabilities and sensory dysfunction The main effect of lead on the blood system is to inhibit the synthesis of hemoglobin, shorten the life span of circulating red blood cells, and eventually lead to anemia; mercury poisoning is characterized by excitability, stuttering and anxiety , lack of concentration, memory loss, mental depression, etc.; hexavalent chromium is an ingestive / inhaled extremely toxic substance Skin contact may lead to sensitivity, more likely to cause genetic genetic defects, inhalation may cause cancer, and has a long-term risk to the environment 2 at present, the kinds of poisonous and harmful elements in the paint are controlled in the relevant laws, regulations and standards, which generally put forward the requirements for soluble elements and total elements respectively For example, the EU WEEE (waste electrical and electric NIC equipment (WEEE) Directive (2002 / 96 / EC) puts forward the limit requirements for four elements of lead, cadmium, mercury and hexavalent chromium; the American Toy Safety Standard Consumer Safety Specification (ASTM F 963-2011) not only requires soluble lead, cadmium, chromium, mercury, antimony, arsenic, barium and selenium in toy coatings The content of total lead was further limited The standard GB 18581, which has been issued and implemented in China, is the first standard to put forward the limit of toxic and harmful elements in the coatings It was revised in 2009 to control the limit of four elements, namely, soluble lead, cadmium, chromium and mercury This year, it has successively released and implemented the limit of specific harmful elements in coatings for consumer products in contact with human body (GB / T 23994-2009), the limit of harmful substances in automobile coatings (GB 24409-2009), and the limit of harmful substances in toy coatings (gb24613-2009) In order to protect human health and environmental safety, the limits of toxic and harmful elements in coating products were further strengthened The detection methods of toxic and harmful elements in coatings at home and abroad at present, the detection methods of toxic and harmful elements in coatings mainly include spectrophotometry, atomic absorption spectrometry (AAS), inductively coupled plasma atomic emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), atomic fluorescence spectrometry (AFS) and X-ray fluorescence spectrometry (XRF) Because there are a lot of organic matters in the coating, and the content of toxic and harmful elements in the coating is generally low, appropriate pretreatment must be carried out before analysis At present, the commonly used pretreatment methods are high temperature ashing method, mixed acid wet acid digestion method, alkaline digestion method, high pressure digestion method, alkali dissolution method and microwave digestion method [1] The detection of toxic and harmful elements can be divided into soluble element detection and total element detection Different pretreatment methods and analysis methods are selected according to different detection purposes 3.1 sample pretreatment coating sample pretreatment is an important link in the detection process, which has a direct impact on the accuracy of the analysis results and is the key point to determine the accuracy of the test data In the analysis of toxic and harmful elements in coatings, the appropriate pretreatment method must be selected according to the physical and chemical properties of the samples to be tested and the target elements The pretreatment of soluble element analysis in coatings is mainly to dissolve the corresponding elements in the coating by simulating the action principle of human digestive system gastric juice Generally, the coating samples need to be crushed and ground into powder first, and then soaked in 0.07 mol / L hydrochloric acid solution at 37 ℃ for a certain time at constant temperature, so that the soluble elements can be transferred to the hydrochloric acid solution, and then analyzed by instrument after constant volume There are many pre-treatment methods for the detection of the total amount of elements in the paint During the pre-treatment, all the target elements in the sample to be tested need to be transferred out The common methods are listed in Table 1 Examples of common methods: coatings home is focused on coatings, diatom mud, paint coating, coating technology, fire retardant coating news and coating, diatom mud, paint coating, coating technology, fire retardant coating decoration knowledge and decoration effect map,