There are two topics in environmental protection of rubber industry: one is to use environmentally friendly rubber products materials, and the other is to minimize environmental pollution caused by rubber production.
First, environmental protection rubber products materials
The rubber products required to be produced do not contain dangerous substances exceeding the limit value, do not use prohibited dangerous substances, and do not endanger human health.
1. Heavy metals
The types and grades of raw materials of rubber products will affect the content of heavy metals. Therefore, we should pay attention to avoid or reduce the use of raw materials containing chromium and nickel (such as zinc-chromium yellow containing hexavalent chromium and antioxidant NBC containing nickel). The chromium plating layer of mold and skeleton will also bring chromium into the rubber compound, so it is necessary to develop a new chromium plating process with trivalent chromium instead of hexavalent chromium. Rubber overshoes industry should pay attention to the limited value of heavy metals in textiles and leather dyes, and restrict the use of metal complex dyes containing copper, chromium and nickel, so as to avoid the trouble of Italian "toxic" investigation because our shoes were found to contain high content of nickel and azo dyes at the end of 2005.
The content of heavy metals in rubber products is not only from one or two key raw materials, but the sum of all raw materials (including raw rubber). Although some raw materials contain little heavy metals (such as silica and kaolin), we should also pay attention to "many a mickle makes a mickle".
Since the implementation of EU ELV Directive and EEE RoHS Directive, the formulation design and production technology of rubber products have become an important issue.
① Lead-free vulcanization system is adopted.
The system consisting of vulcanizing agent TCY (2 2,4,6-trimethoxytriazine) and Ca/Mg acid-absorbing stabilizer, thiadiazole vulcanizing agent /BaCO3 acid-absorbing agent and vulcanizing agent XL-21(2,3)-methyl dithiocarbamate quinoline) /Ca(OH)2 acid-absorbing agent are all lead-free vulcanizing systems in epichlorohydrin rubber. In addition, the lead monoxide curing system of chlorosulfonated polyethylene rubber (CSM) has serious environmental problems, so it can be replaced by lead-free curing system (such as pentaerythritol) or chlorinated polyethylene rubber (CM) in production.
② Cancel the lead vulcanization process of rubber hose.
Plastic coating process is used to replace coated TPX resin (poly -4- methyl-1- pentene), nylon, polypropylene or nylon/polypropylene. As early as 1972, volume 1 of Proceedings of the International Centre for Research on Cancer (IARC) confirmed the carcinogenicity of lead and lead compounds, and two EU directives (67/548/EEC and 76/769/EEC) also listed lead and lead compounds as dangerous substances and set the limit values. At that time, European rubber hose manufacturers were about to give up the lead cladding device. At this time, China's rubber hose industry set off a wave of introducing continuous lead-clad units, and introduced several production lines from Europe, some of which are still in operation today. Moreover, at that time, the cable industry was also popularized and applied, and domestic lead-clad units also developed. This was a decision-making mistake caused by the lack of environmental awareness and information at that time, which should be taken as a warning.
③ Use environmentally friendly adhesive.
Some rubber/metal vulcanizates (such as Kemlock 220, 250, 252) contain lead compounds, which will lead to products exceeding the standard. At present, cilbond 24C, developed by Xibang, UK, is a high-performance adhesive that meets the requirements of International Raw Materials Information System (IMDS). It contains no lead and no toxic solvent. Used for thermal vulcanization bonding between various rubbers and hard substrates such as metals and plastics.