Liquid Rubber (LNBR)
The liquid series (LNBR) is a type of rubber that has a main chain structure composed of butadiene and acrylonitrile, which can contain other functional groups or not, and is in a viscous liquid state at room temperature, with a number-average molecular weight typically below 10,000. LNBR is a new type of low molecular weight liquid toughener, plasticizer, and rubber softener. The liquid is a viscous liquid rubber developed based on rubber. It is pale yellow, transparent, and odorless. Liquid functions: reactive plasticizer & softener.
As a special variety of rubber, the production scale and output of liquid rubber are very small, with manufacturers like PetroChina Lanzhou Petrochemical Company producing less than 100 tons annually.
2. Product Performance Introduction:
From the perspective of "plasticizer", the liquid functions as a high molecular weight rubber with plasticizer properties.
During the rubber vulcanization process, the liquid is "vulcanizable" (can co-vulcanize with sulfur or peroxides).
From the perspective of "processing aids", the liquid serves as a physical and chemical modifier with softener properties.
It can improve the following properties of rubber:
1) Improve processing operability (flowability of the rubber compound; rigidity of low hardness rubber; flexibility of high hardness rubber; self-adhesion during rubber processing, etc.);
2) Enhance the physical and processing properties of low hardness rubber products;
3) Improve mechanical properties when used with white carbon black or clay;
4) Improve adhesion to metal materials and glass materials when using LXNBR;
5) Can co-vulcanize with NBR, CR, ACM, FKM, CSM, ECO, SBR, etc.
6) No migration in products and no extraction in solvents, which improves aging resistance and chemical resistance of products.
From the perspective of production scale and application range, liquid rubber occupies an important position among all liquid rubbers, with a relatively large variety and grades. Liquid rubber usually contains functional groups. From the molecular chain structure, liquid rubber can be divided into three categories: the first category does not contain functional groups; the second category has functional groups distributed randomly in the molecular chain; the third category has functional groups only at the ends of the molecular chain. Specific grades are further divided based on the content of acrylonitrile and molecular weight.
The synthesis of liquid rubber (LNBR) mainly employs a free radical polymerization process, specifically emulsion polymerization and solution polymerization based on the free radical mechanism.
The emulsion polymerization process flow is shown in the figure below:
The solution polymerization for preparing the liquid uses very little solvent, which is similar to bulk polymerization. The process flow is shown in the figure below:
Liquid can be widely used in PVC resin, SBS/ABS thermoplastic elastomers and rubber, acrylic rubber, fluororubber, hydrogenated rubber, chloroprene rubber, and other specialty rubbers.
(1) Plasticizer for Polyvinyl Chloride Resin (PVC)
Using liquid (LNBR) can replace DOP, DBP, DOA, DOS, and solid plasticizer powder rubber, while improving the cold resistance, heat/light/aging resistance, oil resistance of PVC products, increasing the rebound, impact resistance, and surface molding effects of the products, and can improve the migration of plasticizers in products. It can be used to produce: wire/cable materials, automotive dashboards, automotive bumpers, plastic films, irrigation water hoses, core materials for mining conveyors, shoe industry, brake pad industry, etc.
(2) Plasticizer
Due to the good compatibility of liquid (LNBR) with other rubbers and its difficulty in being extracted by solvents, it can serve as a non-extractable special plasticizer. When producing printing rollers, using liquid rubber instead of black and white paste or dioctyl phthalate as a softener can improve the processing performance of the rubber roller as well as the strength, elongation, and rebound of the products, and can also enhance the performance and printing quality of the rubber roller.
(3) Adhesives
Liquid (LNBR) has excellent oil resistance and adhesion, along with good flowability, and can be combined with phenolic resins, epoxy resins, etc., to create strong adhesion with good rebound and oil resistance.
(4) Coatings
Liquid (LNBR) can be used to manufacture low-temperature coatings, anti-corrosion coatings, electrical insulation coatings, water-soluble and electrophoretic coatings, with advantages like toughness and impact resistance.
(5) Application in Solid Rocket Propellants
In solid rocket propellants, liquid (LNBR) is used as an adhesive.
