|Posted by pvac.sales on April 27, 2012 at 9:50 PM|
polyvinyl acetate (pvac) has large applications in Adhesives. For the application in Adhesive industry, previously the market is widely occupied by Wacker, Synthomer, Sekisui and Colomblia Chemicals, but now with the joining of YY PVAc, the market share is going to change. As the polyvinyl acetate provided by YY PVAC is in equivelent quality and better price, It will take the places of the previous market occupiers.
Polyvinyl acetate (PVAc) (Vinyl Acetate Homopolymer) includes polymers of all molecular weights formed from the free radical polymerization of vinyl acetate monomer. These homopolymers are sold as latex, emulsion, or spray dried solids. The spray dried polyvinyl acetate emulsions can be reconstituted in water, mixed with other adhesive emulsions, or mixed with other dry ingredients, where they have the ability to be used as a binder in dry mix formulations.
The PVAc emulsions are, by far, the major form in which polyvinyl acetate is used in the adhesive market. PVAc emulsions exhibit excellent compatibility with many modifying resins, lending themselves to a broad range of applications through formulation. In addition to compatibility, molecular weight, or grade, and the amount and type of protective colloid used to produce the emulsion affect adhesive properties. Variations in type and quantity of protective colloid used in producing the PVAc emulsion have a major impact on the performance of the adhesive film. Vinyl acetate adhesives that vary from low moisture sensitivity by changing the content and type of protective colloid.
In addition to protective colloids, PVAc homopolymers typically contain functional additives such as wetting agents and plasticizers such as dioctylphthalate or dibutylphthalate. Such modifiers impact adhesion, open times, speed of tack, water resistance and emulsion stability.
There are three major types of stabilization mechanisms used in the manufacture of PVAc homopolymers; polyvinyl alcohol (PVOH), hydroxy-ethyl cellulose (HEC), and surfactants.
Although PVAc films possess good aging characteristics due to inherent inert properties to UV and oxidation, vinyl acetate is hard and water sensitive rendering the films brittle below room temperature. Thus, making PVAc homopolymers inappropriate for exterior uses.
PVAc hompolymers are the lowest cost emulsions while possessing good adhesion to many porous surfaces such as wood and paper.
Packaging and furniture applications involving paper and wood substrates constitute over 90% of the usage of PVAc emulsion adhesives. The balance of the usage involves a wide variety of applications including consumer white glue. The packaging applications include boxboard manufacture, paper bags, paper lamination, tube winding and remoistenable labels. In construction, PVAc is used in prefab construction, including flooring and panel installation. PVAc is not generally used as a primary fastener where great strength is needed.
Alternative systems, such as vinyl acetate/acrylic copolymers and/or vinyl acetate ethylene coplymers (VAE), limit the growth of PVAc in applications requiring properties such as moderate water resistance, flexibility, low temperature adhesion, or specific adhesion to non-porous surfaces, e.g., vinyl or aluminum.
There exists a hurdle rate beyond which PVAc will lose any cost advantage and thus share to VAEs. Historically, this threshold has been a price differential of $0.11 per wet pound vs. VAEs, with VAEs being the higher priced polymers. This resin classification market report on polyvinyl acetate (PVAc) (vinyl acetate homopolymer)estimates 2003 demand with a historical perspective back to 2000 as well as forecasts through 2005 and 2010 within the U.S. Adhesives Industry