In 1988, the concept of green building materials was put forward at the first International Material Science Research Institute. In 1992, the international academic circles further defined the green building materials:" materials with the minimum load on the earth and beneficial to human health in the process of raw material adoption, product manufacturing, use or recycling and waste disposal". For this purpose,green building materials can be summarized as follows:
1. The raw materials used for production shall use as little natural resources as possible and industrial wastes shall be used as much as possible.
2. Adopt low-energy consumption manufacturing process and non-pollution environment technology.
3. During product preparation and production process, formaldehyde, halogenated solvent and aromatic hydrocarbon shall not be used. The product shall not contain mercury and its compounds. Additives and pigments containing lead, chromium, cadmium and their compounds shall not be used.
4. Product design aims at improving living environment and quality of life, which is beneficial to human health. The product is multi-functional, reasonable in function, applicable, artistic and decorative, sound insulation and noise reduction, waterproof, fireproof, heat preservation and energy saving, convenient for construction, safe, reliable, durable, etc.
5. Products can be recycled or reused without polluting the environment.
Environmental protection of PVC plastic window and door profile materials
1.PVC main material
PVC (CH2CHCl) is a kind of thermoplastic polymer compound polymerized by vinyl chloride monomer. Because of its wide range of raw materials, low cost, mature technology and wide use, it has become the second largest general plastic in the world after polyethylene. It is well known that the demand for caustic soda in China is quite large. For every ton of caustic soda produced,0.85 tons of chlorine is produced at the same time and the environmental hazard is considerable if the chlorine is released into the atmosphere.
In order to use harmful chlorine resources reasonably and effectively, most of them are balanced by the development of chlorine and most of them will also cause serious pollution to the environment during production and use, such as the destruction of atmospheric ozone layer by trichloroethane. PVC production is currently the only environmentally-friendly product that bsupports chlorine balance. The production of PVC is the best way to absorb chlorine gas, which is the toxic by-product in chlor-alkali.The production of 1 ton PVC consumes 750-850 kg of hydrogen chloride gas, which effectively meets the requirements of using industrial waste to produce green raw materials.
2. PVC additives
Stabilizer is a necessary additive in PVC processing. At present, the main stable systems used in China are lead salt (including composite lead), organotin, calcium zinc and rare earth. It is internationally recognized that organotin and calcium zinc stabilizers are environmentally friendly. According to the labelling and classification of dangerous substances as amended by EU Directive 67/548/EEC, the vast majority of lead compounds are toxic and lead-containing substances or dust enter the human body through skin absorption and breathing. Lead has a cumulative effect in the human body. The EU limits the maximum exposure concentration of lead compounds in the air to 0.15 mg/m3 and the EU limits the maximum lead content in blood to 70 ug/L for men and 40 ug/L for women. The single lead salt dust used in PVC processing is large and metered for many times, which has great impact on the health of batching workers (the use of flake or granular composite lead stabilizer can reduce the dust flying and reduce the toxicity of lead to human body). Pure white rutile titanium dioxide and calcium carbonate are nontoxic.
Environmental protection in recycling PVC plastic window waste
The nonconforming products, leftover bits&pieces, sawdust, etc. produced in the assembly of plastic windows can be recycled after crushing, screening and grinding. Old plastic windows can be recycled. Firstly, the hardware, steel lining, wool strip and glass are recycled by classification. Secondly, the plastic windows are broken as a whole and the glass metal and plastic are recycled by classification through different procedures.
Through the above analysis, the following conclusions can be drawn: from the whole process of energy utilization, raw materials, production to recycling, as long as non-toxic auxiliaries are selected, advanced equipment is used and the process is well controlled,no environmental pollution will occur. PVC plastic windows and doors are environment-friendly products with high evaluation.