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PVP has excellent surface activity and can be used as a component of some detergents to achieve good results. It is widely used in shampoo, hair care products, skin care products, decorations, etc. At the same time, as a pharmaceutical excipient, PVP's main functions are as a binder for tablets and granules, a cosolvent for injections, a stabilizer, a dispersant for liquid preparations, a coating film-forming agent and a pigment dispersant, a coprecipitant for poorly soluble drugs, a delay agent for eye drops, a lubricant, etc.
Definition of K value: PVP povidone can be divided into several grades according to the size of molecular weight, generally expressed by K value. K value is a parameter that does not change with the concentration of povidone. The larger the K value, the higher the molecular weight grade.
Relationship between K value and molecular weight: The relationship between K value, viscosity (ŋ) and average molecular weight (MV) can be seen in the following table:
| Item | Specification | |||||
| Apperance | White or yellowish-white, hygroscopic pyodine powder or China povidone K90 flakes | |||||
| Solubility | Freely soluble in water, in ethanol (96 percent) and in methanol, very slightly soluble in acetone | |||||
| Identification B | An orange-yellow precipitate is produced | |||||
| Identification C | A pink colour is formed | |||||
| Identification D | A red color is produced | |||||
| Appearance of solution | Solution A is cleared, and not more intesely coloured than reference solution BS6 or BYS6 | |||||
| PH | 4.0-7.0 | |||||
| K value | 85.0-95.0 | |||||
| Aldehydes | NMT 500PPM | |||||
| Peroxide | NMT 400PPM | |||||
| Formic Acid | NMT 0.5% | |||||
| Hydrazine | NMT 1.0PPM | |||||
| Impurity A (1-Vinyl-2-pyrrolidone) | NMT 10.0PPM | |||||
| Impurity B (2-pyrrolidone) | NMT 3.0% | |||||
| Water | NMT 5.0% | |||||
| Sulfated ash (Residue On Ignition) | NMT 0.1% | |||||
| Nitrogen | 11.5%-12.8% | |||||
| Heavy Meatal (Lead) | NMT 10PPM | |||||
| Particle Size | 100% pass 20 mesh and 50% pass 40 mesh | |||||
Application of different K values: Low molecular weight Povidone (povidone K17/PVP K25/PVP K30) is usually used as a solubilizer, crystallization inhibitor and suspension stabilizer in injections and ophthalmic preparations, and high molecular weight Povidone (K60/K85/povidone K90/K120) is usually used as a high-efficiency adhesive, stabilizer, thickener, and hydrophilic agent for oral or topical suspensions.
In the oil production industry: PVP can be used as a mud additive to increase viscosity and curing time and reduce water loss rate. Since it is less sensitive to salt concentration, it can be used as a polymer flooding tool in water-sensitive areas at high salt concentrations.
Papermaking technology: PVP povidone can improve the wet strength of paper, the solubility of dyes, and the dispersibility of pigments. It is an excellent auxiliary agent for deinking, pulping, and coloring, and an anti-caking agent and flow aid for coatings, making the final paper product smooth, oil-releasing, and printing performance good. For those occasions where paper still needs to be wetted after coating, PVP can prevent the paper from curling and wrinkling.
Quenching liquid: PVP can be used as a quenching liquid to avoid the re-cargo caused by using an oil bath, and the cooling rate can also be controlled accordingly. At the same time, since the specific heat capacity of PVP quenching liquid is almost twice that of oil, the temperature rise of PVP quenching agent only requires half of the same volume of oil, which increases the output of quenching liquid.
Pesticide industry: Since PVP is non-phytotoxic, it can be used in plant protection sprays, fertilizers and wettable pesticides. PVP film can protect leaves from wilt during transplantation and reduce damage from wind and frost. PVP can reduce soaking damage to seeds and protect their physiological functions.
