Plasticizers, also known as softeners, refers to a class of low molecular weight compounds that can reduce the force between the rubber molecular chains, improve the performance of the processing process, and improve the physical and mechanical properties of the rubber, reduce costs.
The role of plasticizer
1. Improve the processing performance of rubber: by reducing the intermolecular force, make the powdery cooperating agent better infiltrate with the raw rubber and disperse uniformly, improve the mixing process; by increasing the plasticity, fluidity, adhesion of rubber to improve the calendering, extrusion, molding process.
2. Improve some physical and mechanical properties of rubber: reduce the hardness of products, fixed tensile stress, improve the elasticity of vulcanized rubber, cold resistance, reduce the heat.
3. Reduce cost: low price, energy saving.
Classification of plasticizers
1. According to the mechanism of action:
Physical plasticizers: plasticizing molecules into the rubber molecule, increasing the molecular spacing, weakening the intermolecular forces, molecular chain easy to slide.
Chemical plasticizers: also known as plasticizer, through the force of chemical action, so that the rubber macromolecule chain breakage, increase plasticity.
Most of them are derivatives of aromatic thiophenols such as 2-naphthalene thiophenol, dimethylphenyl thiophenol, pentachlorothiophenol and so on.
2. According to the source:
① petroleum-based plasticizers
② coal tar plasticizer
③ pine oil plasticizer
④ Fatty oil plasticizers
⑤ synthetic plasticizers
IV. Requirements for plasticizers
Good plasticizing effect, low dosage, fast absorption;
Good compatibility with rubber, small volatility, no migration, good cold resistance, water, oil and solvent resistance;
Good electrical insulation, good flame resistance, colorless, non-toxic, odorless, inexpensive and easy to obtain.
The main cold-resistant plasticizer varieties are:
Dioctyl adipate (DOA): excellent cold resistance, but oil resistance is not good enough, volatile.
Dioctyl azelate (DOZ): excellent cold resistance, low volatility, heat resistance, light resistance, good electrical insulation.
Dioctyl sebacate (DOS): excellent cold resistance, low volatility and excellent electrical insulation, but poor oil resistance.
Dibutyl sebacate (DBS): good cold resistance, but volatility, easy to migrate, easy to extract.
Rubber cold plasticizer varieties
NBR commonly used DOP, DBP, TCP, etc., for cold products can be used DOA, DOZ, DBS, etc., oil can be selected polyester plasticizers.
CR usually use 5~10 parts of petroleum-based plasticizers, but for cold-resistant products, ester plasticizers should be used for oil-resistant products can be selected polyester plasticizers.
SBR: petroleum-based plasticizers are used to improve processing performance; fatty acids and fatty acid esters plasticizers can be used to improve cold resistance.
IIR: DOA and DOS plasticizers can be used to improve cold resistance; polyester plasticizers can be used to improve oil resistance.