Medical Use PVA
Polyvinyl alcohol in Medical Field
Medical Uses PVA (Polyvinyl Alcohol)
Polyvinyl Alcohol: A wide range of possibilities
Polyvinyl Alcohol (PVA) is a synthetic, biocompatible and toxicologically safe polymer that is exceptionally well suited for a variety of pharmaceutical applications: In tablet coatings, for example, it protects the tablet from environmental humidity, in eye drops it moistens the eye, and in cell fermentation processes Polyvinyl Alcohol prevents bubble rupture to protect cells from shearing. Merck makes it easy to fully exploit the possibilities of Polyvinyl Alcohol:
PVA: Designed to suit your needs
Polyvinyl alcohol (PVA) is exceptionally well suited for large-scale commercial use as an excipient in various pharmaceutical products such as tablet coatings, eye drops, biofermentation and topicals. PVA is biocompatible, toxicologically safe, water-soluble and suitable for simulation of natural tissues. It has good oxygen permeability, shows no immunogenic effects, and features excellent film forming, emulsifying and remoistable properties.
Benefit now: PVA in pharmaceutical quality
As drug approval procedures grow ever more stringent, regulatory requirements are becoming more and more demanding – not only for active pharmaceutical ingredients, but for excipients as well. Therefore, manufacturers need pharmaceutical-quality raw materials in order to ensure consistent product quality and safety. EMD offers PVA fully regulated as an excipient for pharmaceutical applications in the quantities required for large-scale commercial use. PVA EMPROVE® Ph Eur, USP is available in a variety of viscosities and grades of hydrolysis to suit various applications and uses.
Industrial Uses PVA
1.Papermaking & processing
In papermaking, water-soluble polymers are mainly applied to surface sizing agent, pigment binding agent, and paper addictive. In the past starch-based pigment was used as a surface sizing agent and casein as a binding agent. Today since the adhesion of PVA to fibers is stronger than casein, with better film-forming property and higher intensity of the film, the demand of PVA for paper processing is on the rise. Along with the large-equipment involving, high efficiency and high-grade papermaking and reasonable ways of packing, such demand will be even greater. Main applications: (1) binding agent for paper; (2) re-moistening agent; (3) paper surface sizing; (4) paper pigment coating; (5) papermaking (paper internal sizing). Applicable varieties: 24-99, 20-99, and 17-88 etc.
2. Plywood, artificial board and timber processing
PVA can be a de-characterizing agent of thermosetting resin mainly used as a binding agent such as carbamide, formaldehyde resin and melamine, for plywood, artificial board and timber processing. When mixed with melamine-formaldehyde resin, the PVA size paste helps increase the viscosity and shortens both curing and cooling time with stronger initial cohesion. Commonly used varieties: 17-99, 20-99, and 24-99 etc.
3. Emulsifying and stabilizing agents
With its very low surface tension and its ability to disperse VAC in water into very fine granules, PVA is applied to produce PVAc emulsion. It is also a very good protective colloid that enables the polymerized, colloidal and granular PVAc to form a stable aqueous emulsion and keep it from coagulation or degradation. Selection from a variety of PVA products depends on their properties. As for latex with a strong cohesion at the beginning of production, the complete alcoholysis type PVA can be selected, such as those labeled 24-99, 18-99, 20-99 and 17-99; on the contrary, for production of latex with low viscosity despite high content of solid, a PVA with a low degree of polymerization may be mixed with a PVA with high alcoholysis, and 03-88 can be used together with 17-99.
4. Construction Industry
PVA polyvinyl alcohol is used as an addictive to cement and mortar for efficient increase of their cohesion and fluidity, and reduce the drying time for the concrete surface, thus increasing coating adaptability and preventing concrete cloth from chapping. Besides, due to its simple application method with desired effects, PVA is suitable for wall and ceiling decoration and tile facing.
polyvinyl alcohol can be also used as an adhesive agent for profiles, e.g. prefabricated plasterboard and sound absorption board that are made of organic fibers (cane, residue and wood-shavings) or non-organic materials on which highly cohesive and waterproof PVA series can be applied to make profiles through compression and cohesion.
The PVA solution, a poly vinyl formal (PVFM) high molecular compound, finds its wide application in internal wall coating, plasterwork and joint sealing due to its favorable properties of weather resistance, waterproof, non-swell with water, non-embrittlement, non-poison, tastelessness, and inexpensive prices.
In the coating sector the traditional varieties can only be used in making profiles. PVA with a higher degree of polymerization, such as the models 20-99 and 24-99, are often selected as a substitute.
5. PVA Film
PVA film has many unique advantages unmatchable for general polypropylene and polyvinyl chloride (PVC) due to its properties of bearing static electricity, good optical transmission, good gloss, low oxygen permeability, and coriaceous coating.
In this sector traditional varieties are seldom used. Due to low viscosity of PVA 17-99 series, generally for membrane not easily soluble, PVA 20-99 and 24-99 may be used, whereas the PVA 17-95 and 17-88 may be often used for production of water-soluble membranes.
For the PVA film which contains dichromatidgelatin or cinnamon acid, after ultraviolet radiation, part of the PVA combines with dichromatidgelatin to produce insoluble complex salt, or with cinnamon acid to have a water-insoluble meshwork due to the bridging effect. After heat treatment for increase of physical strength, the meshwork can be used for screen printing.
Functional PVA is now the most efficient synthetic sizing agent for warp paste with the following advantages:
(1). PVA membrane has a good sizing effect and can improve the weavability of high-density and high-grade textiles due to its excellent properties of obdurability, smoothness, wear resistance and adhesiveness on fibers.
(2). PVA has a powerful cohesive force on fibers as well as good protective effects to reduce times of textile yarn breaking and improve weaving efficiency.
(3). PVA size paste doesn’t not get corrosive easily and degraded without any change in viscosity after long-time heating, which ensures stable sizing and minimizes hard size spots.
(4). At textile factories the moisture of starch paste must be at 80-85%, while the moisture requirement for PVA size mixture is just 70-75%, which makes it possible to improve operating environment and production efficiency.
(5). To minimize desizing in the process of sizing and weaving and keep the factory area clean, PVA series with medium degrees of polymerization and 90-97 (mol/mol)% alcoholysis, such as 20-95 and 17-95, are applicable.
Though its clothing property may be far less popular than other synthetic fibers, Vinylon is still known for its properties of moisture absorption and wear resistance and can substitute some cotton-made bedding, knitwear, decorative cloth, canvas, uniform, work clothes, fishing net and curtain. Other properties of vinylon meet industrial requirements, such as high strength, low elongation, high modulus, acid/alkali/weather resistance, good adhesiveness to rubbers. So high-strength and high-membrane vinylon can be used as an alternative to asbestos.