Plastics have odor and seven treatment methods

The reason why plastic has odor:

Miscellaneous materials

Multiple processing degradation of materials

Decomposition of small molecular materials in materials

Sometimes the water and some materials have a strong accelerated degradation

Since the additive or the recycled material is added to the plastic product, the product contains ethylene, sulfur dioxide, hydrogen sulfide, amine, ammonia odor or other odor. A part of the odor is released after the product has been stored for a period of time; sometimes it is lurking in the plastic product, and the secondary processing of these harmful gases is released to constitute the odor of the plastic. A typical method for solving odors is to add a gas adsorbent and an antibacterial agent to the plastic to prevent the generation of unpleasant odors due to the action of bacteria and fungi. Residual odor can also be reduced by solvent extraction and venting.

Plastic odor treatment method:

1, the correct use of additives

The tertiary amines used in the production of polyurethane foams often give rise to strong odors and fog on the interior windows of automobiles. The solution to this problem is to find alternatives to these amines. If a polyhydroxy compound is used, the polyhydroxy compound is not only a component of the polyurethane molecular chain, but also has catalytic activity.

The phenolic stabilizers used in PVC extrusion or calendering are often replaced by low odor zinc stabilizers. The heat stabilizer tin octylate is also commonly used in automotive PVC products due to its low odor and low atomization properties. Plant extract oils such as erucic acid and oleic acid are amine lubricants (for polyolefins). And the odor of styrenic food packaging materials) is much smaller.

2. Processing of recycled materials

The organic solvent extraction method helps to remove odor-causing compounds. The latest solvent extraction method also uses supercritical carbon dioxide as a solvent. This technology has been applied to HDPE and PET to remove odorous contaminants from oil containers, pesticide containers and other waste devices. The benefit of carbon dioxide extracts is that they do not cause troublesome post-treatment problems with organic solvents.

The odour removal unit is an integral part of the waste plastic pellet extruder and is also effective in removing some of the highly volatile compounds that produce odors.

3, using a more pure resin

In many plastics, especially in plastics such as polyvinyl chloride, styrene, polyethyl acetate and acrylates, residual traces of monomers can produce unpleasant odors. Those odors can be eliminated by using a resin with a small amount of monomer remaining.

4, adding adsorbent

If a small amount of zeolite (an aluminosilicate adsorbent) is filled in the polymer, the effect of removing the odor of the material can be achieved. Zeolites have a large number of crystalline voids that capture small molecules of odorous gases.

Molecular adsorbents have been successfully applied to polyolefin extruded tubing, injection and extrusion blow molded containers, insulation packaging materials, extruded outer packaging materials and sealing polymers. Molecularly adsorbed powders can also be added to plastics as moisture absorbers to remove moisture, which can also contribute to the odor of plastic products.

5, the use of antibacterial agents

Adding an antibacterial agent to the plastic not only reduces the odor it emits, but also delays the aging, discoloration and embrittlement of the surface of the product. The most commonly used antibacterial agents are 10,10'-oxobiphenone oxime (OBPA), triclosan, isothiazolinone (OIT), pyrythione. Organometallic compounds containing tin and silver are sometimes also used as antibacterial agents.

6, using the desorption method

Another method of deodorization is to place the plastic in an odor sorbent such as activated carbon and high surface area silicate. The vacuum treatment environment can accelerate the desorption process. Treatment of plastic particles with a special detergent solution can also help to remove odors. Generally these detergents are aqueous or alkaline solutions containing surfactants. These detergents can effectively remove vinyl chloride monomers, styrene, acrylates, acrylic monomers, and unsaturated hydrocarbons.

7, add fragrance

Adding a fragrance to a plastic does not eliminate the unpleasant odor, but it can cover these odors, which in many cases is sufficient. The method can be applied to polyethylene, polypropylene and polyolefin thermoplastic elastomers by injection molding, extrusion or blow molding. The retention time of the fragrance does not necessarily equate to the life of the molded part. The retention time depends on the degree of aggregation, the volume to surface area ratio, whether it is exposed to a heated or humid environment, and whether the molded part is tightly insulated from air packaging. Fragrances are generally used in household goods, cosmetic containers, household appliances, and the like.