VINNAPAS® 920 is a carboxylated, poly(vinyl alcohol) stabilized, vinyl acetate-ethylene (VAE) copolymer dispersion with a glass transition temperature (Tg) of -20 °C. It offers excellent flow, wet out and adhesion to a wide variety of polymeric films, coatings and other difficult substrates.
VINNAPAS® 920 is extremely versatile because it is compatible with many other raw materials and polymer systems. The viscosity and rheology can be modified with the addition of poly(vinyl alcohol), cellulose thickeners, starch, inverse polyacrylate dispersions, or associative thickeners. The viscosity can also be increased with the addition of alkalis which neutralize the carboxyl functional groups or through the addition of sulfonated alkyl-ester-based wetting agents. Addition of plasticizer will have only a marginal affect on viscosity thickening. VINNAPAS® 920 does accept high loadings of fillers. Extremely high levels of fillers require that they be pre-dispersed.
VINNAPAS® 920 has excellent wet out and adhesion to difficult-to-adhere substrates like polymeric and metallized polyethylene, polypropylene, and polyester teraphthalate films. It can be used in various specialty packaging and converting adhesive formulations to promote adhesion as the primary base dispersion or as an adhesion promoter for applications including but not limited to film to board/paper laminating, carton window film and specialty folding carton manufacturing. The unique properties of this dispersion allow it to be used as an adhesion promoter and modifier in other formulations where flow, wet-out, and specific adhesion are required. VINNAPAS® 920 is a semi-pressure sensitive VAE offering low tack and high shear dry film properties. It can be useful in enhancing the shear properties of other pressure sensitive polymer systems.
When the dispersion is stored in tanks, proper storage conditions must be maintained. If stored in the original, unopened containers at cool (below 30 °C), but frost-free temperatures the product has a shelf life of 9 months from the date of manufacture. Any longer periods for the maximum storage period that may be described in the Certificate of Analysis which accompanies each shipment of the product, take preference over this suggestion in which case the time period stated in the Certificate of Analysis shall be solely authoritative. Iron or galvanized-iron equipment and containers are not recommended because the dispersion is slightly acidic. Corrosion may result in discoloration of the dispersion or its blends when further processed. Therefore, the use of containers and equipment made of ceramics, rubberized or enameled materials, appropriately finished stainless steel, or plastic (e.g. rigid PVC, polyethylene or polyester resin) is recommended. As polymer dispersions may tend to superficial film formation, skins or lumps may form during storage or transportation. Filtration is therefore recommended prior to utilization of the product.
Preservation for Transport, Storage and further Processing
The product is adequately preserved during transportation and storage if kept in the original, unopened containers. However, if it is transferred to storage tanks, the dispersion should be protected against microbial attack by adding a suitable preservative package. To maintain proper storage conditions appropriate measures should also be taken to ensure cleanliness of the tanks and pipes. In a storage tank in which the product is not stirred, it is advisable to contact your biocide representative/supplier. Proper procedures must be set up in order to prevent microbial attack between necessary periodic tank cleaning and sanitization. These procedures will vary, since loading and unloading practices in each storage situation will differ slightly. Finished products manufactured from polymer dispersions usually also require preservation. The type and scope of preservation will depend on the raw materials used and the anticipated sources of contamination. The compatibility with other components and the efficacy of the preservative should always be tested in the respective formulation. Preservative manufacturers will be able to advise you about the type and dosage of preservative required.