What to do if plastic products have peculiar smell
Plastic products emit unpleasant odors during processing. To overcome this problem, efforts have long been made to reduce these odors. In addition, many friends will add a certain proportion of recycled materials to the new materials, and the taste will be heavier during granulation production, which is a common problem in production. Now, some solutions are provided.
The reason why plastic smells
1. The material is very complicated
2. The material is processed and degraded many times
3. Decomposition of small molecular materials in materials
4. Moisture accelerates the degradation of materials
Odors or other odors of ethylene, hydrogen sulfide, sulfur dioxide, amines and ammonia are carried in plastics when additives or recycled materials are added to them. Some odors are released after the product is stored for a period of time; sometimes lurking in the product, these harmful gases are released during the secondary processing and constitute the odor of the plastic.
A typical solution to odors is to add gas adsorbents and antibacterial agents to plastics to prevent unpleasant odors caused by bacteria and fungi. Residual odors can also be reduced by solvent extraction and venting.
Odor treatment of plastics
1. Correct use of additives
The catalyst tertiary amines used in the production of polyurethane foam tend to bring strong odors and fog the interior windows of automobiles. The solution to this problem is to find alternatives to these amines. If a polyol is used, it is not only a component of the polyurethane molecular chain, but also has catalytic activity.
Phenolic stabilizers used in PVC extrusion or calendering are often replaced by low-odor zinc stabilizers. The heat stabilizer tin octoate is also commonly used in automotive PVC products due to its low odor and low fogging properties. Vegetable oils such as erucic and oleic acids are much less odorous than amine-based lubricants made from animal oils.
2. Handling of recycled materials
Organic solvent extraction helps remove odor-causing compounds. Supercritical carbon dioxide can also be used as a solvent. Has been applied to HDPE and polyester to remove malodorous contaminants from oil containers, pesticide containers and other waste installations. The advantage of carbon dioxide extractants is that they do not introduce the troublesome post-processing problems of organic solvents.
3. Use purer resins
In many plastics, especially in plastics such as polyvinyl chloride, styrene, polyvinyl acetate, and acrylate, residual trace monomers will produce unpleasant odors. These odors can be eliminated by using resins with very little residual monomer.
4. Add adsorbent
If a small amount of zeolite is filled in the polymer, the odor of the material can be removed. Zeolite has a large number of crystal voids that trap small odorous gas molecules.
Molecular sieve adsorbents have been successfully used in polyolefin extruded pipes, injection and extrusion blow molded containers, barrier packaging materials, extrusion molding overwrap materials and sealing polymers. Molecular sieve adsorption powder can also be added to the plastic as a hygroscopic agent to remove water vapor and also help plastic products to produce odor.