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There are reasons for the smell of plastic and seven solutions
Oct 23, 2017

Plastic products in the processing process will be have unpleasant smell, in order to overcome this problem, we have long been committed to reducing these scents. In addition, many of my friends will be in the new material mixed with a certain percentage of the recovery of materials, granulation production heavier taste, which is a production of ubiquitous problems, and now offers seven solutions.


Reason for plastics having unpleasant smell:

  • Material is more complex

  • Repeated processing degradation of materials

  • Decomposition of Small Molecule Materials in Materials

  • Sometimes the water and some of the material from the strong accelerated degradation

 

As the plastic products by adding additives or recycled materials, so that the plastic products with ethylene, hydrogen sulfide, sulfur dioxide, ammonia, ammonia odor or other odor. Part of the smell in the products stored for some time after the release; sometimes lurking in plastic products, the secondary processing of these harmful gases are released, constitute the smell of plastic. A typical method for solving the odor is to add a gas adsorbent and an antibacterial agent to the plastic to prevent the occurrence of those unpleasant odors due to the effects of bacteria and fungi. It is also possible to reduce the residual odor by solvent extraction and exhaust.


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Odor treatment for plastics


1. the correct use of additives

        

Polyurethane foam production process used in the catalyst of tertiary amines often bring a strong smell, but also in the car window fog. The solution to this problem is to find alternatives to these amines. If polyhydroxy compounds are used, the polyhydroxy compound is not only a component of the polyurethane molecular chain but also has a catalytic activity.

        

Phenol stabilizers used in PVC extrusion or calendering are also often replaced by low odor zinc stabilizers. Heat stabilizer tin octylate is also used in automotive PVC products due to its low odor and low atomization properties. Plant extracts such as erucic acid and oleic acid are much smaller than the odor of amine-based lubricants (for polyolefin and styrenic food packaging) made from animal extracts.

 

2. the processing of renewable materials

        

The organic solvent extraction process helps to remove the odor-producing compounds. The latest solvent extraction method also uses supercritical carbon dioxide as a solvent, which has been used in HDPE and PET to remove contaminants from oil containers, insecticidal containers and other waste devices. The advantage of the carbon dioxide extractant is that it does not cause the problem of post-handling of organic solvents.

        

Odor removal devices are an integral part of a waste plastic particle extruder that also effectively removes some of the strong volatile compounds that produce odor.

 

3. the use of more pure resin

        

In many plastics, especially in plastics such as polyvinyl chloride, styrene, polyacetate and acrylic esters, residual micro-monomers produce unpleasant odors. The use of resin with little residual monomer can eliminate those odors.

 

4. add the adsorbent

        

If the polymer is filled with a small amount of zeolite (an aluminosilicate adsorbent), it can remove the odor of the material. The zeolite has a large number of crystalline voids, which can capture small molecules with odor.

        

Molecular adsorbents have been successfully used in polyolefin extrusion pipes, injection and extrusion blown containers, isolated packaging materials, extruded outer packaging materials and sealing polymers. Molecularly adsorbed powders can also be added as a moisture absorption agent to the plastic to remove water vapor, which also contributes to the odor of plastic products.

 

5. the use of antibacterial agents

        

Adding antibacterial agents to plastics can not only reduce the odor of their emissions, but also delay the aging of the product surface, discoloration and brittle. The most commonly used antimicrobial agents are 10, 10'-oxobisbenoxybenzene (OBPA), triclosan, isothiazolinone (OIT), pyrithione (Pyrithione). Organometallic compounds containing tin and silver are also sometimes used as antibacterial agents.

 

6. the use of desorption method

        

There is also a deodorant method of placing the plastic in an odor adsorbent such as activated carbon and high surface area silicates, which can accelerate the desorption process. Treatment of plastic particles with a special detergent solution can also help to remove the odor. In general, these detergents are aqueous or alkaline solutions containing surfactants. These detergents can effectively remove vinyl chloride monomer, styrene, acrylic, acrylic and unsaturated hydrocarbons.

 

7. adding fragrance

        

Adding fragrance to the plastic does not eliminate the unpleasant smell, but it can cover the smell, and in many cases it is enough to achieve it. The method can be applied to polyethylene, polypropylene and polyolefin thermoplastic elastomers, the processing methods are injection molding, extrusion or blow molding.

        

The retention time of the fragrance is not necessarily equivalent to the life of the molded part. The retention time depends on the degree of aggregation, the volume area ratio, the exposure to the heated or humid environment, and whether or not the molded part has been tightly insulated. Fragrance is generally used in toys, household goods, cosmetic containers, household appliances and gardening equipment.


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