POLYVINYLPYRROLIDONE K 90

Polyvinylpyrrolidone K 90, a high-molecular-weight, water-soluble synthetic polymer obtained by polymerization of the N-vinylpyrrolidone monomer. This grade, with a K-value of 90, is supplied as a white to slightly yellowish, hygroscopic powder; it dissolves in water, ethanol, isopropanol and many polar solvents. Its average molecular weight is reported as roughly 900,000 to 1,700,000, depending on the manufacturer and the measurement method; its solutions are viscous.

Povidone K 90, used as a strong binder in tablet granulation at a level of roughly 1–5 percent. In hair gels and mousses it provides consistency and strong hold, and in poorly soluble active ingredients it acts as a matrix that retards crystallization. Thanks to its long-chain structure it gives high viscosity and adhesion strength even at low concentrations.

PVP K 90, a binder, thickener, stabilizer and surface coating agent in many fields, from glue sticks to membrane production, from crop protection products to silver nanowire synthesis and electrospinning studies. In selection, the grade, K-value range, moisture, residual monomer and peroxide level and the manufacturer’s documents should be evaluated together. This product can be supplied from ATAMAN KİMYA; for technical information and requests, contacting ATAMAN KİMYA is recommended.

WHAT IS POLYVINYLPYRROLIDONE K 90?

Polyvinylpyrrolidone K 90 is a linear, non-ionic polymer produced by free-radical polymerization of the N-vinylpyrrolidone (NVP) monomer. It is among the long-chain, high-molecular-weight members of the family; it appears as povidone in pharmacopoeias and food legislation, and in trade it is known under grade names such as K 90 or K-90.

Each repeat unit of the chain carries a five-membered lactam ring, that is, a pyrrolidone group, attached to the main chain. The carbonyl oxygen in the ring is a strong hydrogen-bond acceptor, while the methylene groups give the chain a limited hydrophobic character. This dual character allows the substance to dissolve both in water and in many organic solvents.

The 90 in the name is the K-value, calculated from the viscosity of the polymer in dilute solution using the Fikentscher equation. For grades with a K-value above 15, the European and American pharmacopoeias accept 90–108 percent of the nominal value, which corresponds to a range of 81.0 to 97.2 for K 90.

The manufacturers’ own ranges are narrower. A range of 88.0–96.0 is given for Luviskol K 90, 85–95 for Plasdone K-90 and 90–100 for Agrimer 90; 84.0–95.0 appears for one laboratory product.

K 90 is among the longest-chain grades of the family, well beyond medium grades such as K 30. It gives a viscous solution even at low concentration, and its binding power and adhesion strength are high; on the other hand it takes longer to dissolve and its solution is harder to manage in operations such as spraying.

Manufacturer documents give the molecular weight with different figures. BASF reports a weight-average value of 900,000–1,200,000 for Kollidon 90 Evo; for Luviskol K 90 about 1,200,000 (±100,000), for Ashland Plasdone K-90 about 1,300,000 and for Agrimer 90 1,000,000–1,700,000 are given.

Some laboratory catalogues, however, show a much lower average such as 360,000. One catalogue states this figure as a number-average (Mn). BASF and Ashland, on the other hand, give the weight average by size-exclusion chromatography with a light-scattering detector; the two figures should not be compared directly.

The substance is a white to slightly yellowish powder, odorless or with a very faint odor. It readily takes up water from the environment; it dissolves in water, ethanol, methanol and isopropanol and does not dissolve in ether and hydrocarbons. K 90 powders consist of larger particles than K 30; some grades are also sold as a solution containing about 20 percent solids.

It should not be confused with cross-linked, water-insoluble polyvinylpolypyrrolidone (PVPP, crospovidone). This is a separate substance; it is used as a tablet disintegrant and as a beer and wine clarifier, is known by the code E 1202, and does not replace soluble povidone.

Its main functions are binding, providing tack, increasing consistency, film forming, retarding crystallization, stabilizing suspensions and colloid protection. In products and processes such as tablets, hair gels, glue sticks, crop protection suspensions, membranes and silver nanowire synthesis, one or several of these functions are used together.

Production is based on polymerizing N-vinylpyrrolidone with a free-radical initiator in an aqueous or 2-propanol medium. After the reaction the solution is dried, residual monomer and by-products are reduced to a low level, and the product is offered in different particle sizes.

The name K 90 alone is not enough for selection. The grade (pharmaceutical, food, cosmetic or technical), moisture, residual monomer, peroxide and impurity limits and the manufacturer’s documents should be evaluated together.

COMMON PRODUCT AND CHEMICAL NAMES OF POLYVINYLPYRROLIDONE K 90:

Polyvinylpyrrolidone K 90
Polyvinyl pyrrolidone K 90
Povidone K 90
Povidone K90
Povidone K-90
Povidone K 90 (pharmacopoeial name)
Povidone K90 (pharmacopoeial name)
Povidone K-90 (pharmacopoeial name)
Polividone K 90
Polyvidone K 90
PVP K 90
PVP K90
PVP K-90
PVP USP K 90
Povidone USP
Poly(N-vinylpyrrolidone)
Poly(1-vinylpyrrolidin-2-one)
Poly(1-ethenylpyrrolidin-2-one)
Poly[1-(2-oxo-1-pyrrolidinyl)ethylene]
N-vinylpyrrolidone homopolymer
1-ethenylpyrrolidin-2-one homopolymer
2-Pyrrolidinone, 1-ethenyl-, homopolymer
Vinylpyrrolidone polymer
E 1201
Kollidon 90 Evo
Kollidon 90 F
Plasdone K-90
Luviskol K 90
Luvitec K 90
Agrimer 90

Most of these names describe the same product in different spellings. Povidone is the general name used in pharmacopoeial and regulatory language; polyvidone is an older and less used spelling; PVP is the international abbreviation of polyvinylpyrrolidone.

The names K 90 and K-90 describe the same grade. Ashland offers the product under the name Plasdone K-90; BASF, on the other hand, refers to the pharmaceutical grade as Kollidon 90 Evo, the cosmetic grade as Luviskol K 90 and the technical grade as Luvitec K 90, names separated by application.

Kollidon 90 Evo is the product that replaces BASF’s earlier Kollidon 90 F grade. For Luvitec K 90, the 20 percent solution form is mentioned especially in technical applications such as glue sticks.

Of the trade names, Kollidon, Luviskol and Luvitec are brands of BASF, while Plasdone and Agrimer are those of Ashland. In pharmaceuticals mainly Kollidon and Plasdone are offered, in cosmetics Luviskol, in technical applications Luvitec and in crop protection Agrimer.

Similar names may cause confusion. Polyvinylpolypyrrolidone (PVPP, crospovidone, CAS No 25249-54-1) has a cross-linked, insoluble structure; products sold under names such as Polyclar and Divergan belong to this group. N-vinylpyrrolidone (CAS No 88-12-0) is the monomer of the polymer and is a separate substance.

Copovidone (a copolymer of vinylpyrrolidone and vinyl acetate, CAS No 25086-89-9) is also a different polymer; it is sold under names such as Kollidon VA 64 and Luviskol VA. Povidone-iodine (CAS No 25655-41-8) is a complex of the polymer with iodine and is used as an antiseptic.

When a request or order is written, the product name, the CAS number and the K-value should be stated together. Because products of very different molecular weights are sold under the same CAS number, the CAS number alone does not define the K 90 grade; confusion with neighboring grades such as K 30 is also avoided in this way.

CAS NO, EC / EINECS NO AND CHEMICAL IDENTIFICATION OF POLYVINYLPYRROLIDONE K 90

Product name: Polyvinylpyrrolidone K 90

Common abbreviation: PVP K 90; pharmacopoeial name povidone K 90

Chemical name: Poly(1-vinylpyrrolidin-2-one); 1-ethenylpyrrolidin-2-one homopolymer

INCI name: PVP

Food additive number: E 1201 (INS 1201)

CAS No: 9003-39-8

EC / EINECS No: Because it is a polymer there is no single identifying number; some documents give 201-800-4, the number of the monomer N-vinylpyrrolidone

Molecular formula: (C₆H₉NO)ₙ

Molecular weight: 111.14 g/mol for the repeat unit; in the K 90 grade the weight-average molecular weight is roughly 900,000–1,700,000, depending on the manufacturer and the measurement method; 360,000 on some catalogue labels

K-value: Nominal 90; 81.0–97.2 in the pharmacopoeias

Chemical class: Synthetic, non-ionic, water-soluble polymer; N-vinyllactam homopolymer

Main functions: Binder, tackifier, thickener, film former, crystallization retarder, suspension stabilizer, colloid protector, surface coating agent

Polymers are excluded from the registration obligation under the European REACH regulation; the monomer N-vinylpyrrolidone, on the other hand, is registered, and residual monomer limits are set separately in pharmacopoeias and food legislation. The current status should be confirmed with the supplier.

The CAS number is necessary to match the product with the correct substance; however, it does not indicate the K 90 grade on its own. Pharmaceutical, food, cosmetic and technical grades are sold under the same number and cannot automatically be used in place of one another. For example, the manufacturer’s document for Luviskol K 90 powder states explicitly that it is not intended for use in pharmaceutical preparations.

The existence of an INCI name does not mean that the product can automatically be used in cosmetics, nor does the existence of an E 1201 number mean that every food use complies with the legislation. For each application the grade, the level of documentation and the legal limits should be evaluated separately.

CHEMICAL STRUCTURE AND MOLECULAR PROPERTIES OF POLYVINYLPYRROLIDONE K 90

The main chain is a saturated carbon–carbon backbone formed by the polymerization of the vinyl group. An N-pyrrolidone ring is attached to every second carbon atom; the nitrogen in the ring, together with the carbonyl carbon, forms a tertiary amide, that is, a lactam structure.

For K 90 the chain consists of roughly 8,000 to 11,000 units, with a repeat unit of 111.14 g/mol. This figure is an approximation calculated from the weight-average molecular weight range of 900,000–1,200,000 reported by BASF; the actual distribution is broad and consists of a mixture of short and long chains.

Because there is no hydrogen bonded to the nitrogen atom, the molecule is not a hydrogen-bond donor; it acts only as a hydrogen-bond acceptor through the carbonyl oxygen. In this way it forms strong bonds with hydroxyl-containing substances such as phenols, carboxylic acids and alcohols.

The high dipole moment of the amide group gives the chain a marked polarity. The backbone and the ring methylenes, on the other hand, form apolar regions. This balanced structure explains why the polymer dissolves in water, alcohols, chlorinated solvents and some amines and acids, and does not dissolve in ether and saturated hydrocarbons.

The polymer is non-ionic; it carries no charge in solution. For this reason it can be used together with surfactants, salts, most dyes and acids. The pH of solutions depends less on the polymer itself than on production residues and on the measurement concentration.

As chain length increases, the chains become entangled in solution. For this reason K 90 gives consistency even at very low concentrations. In one nanosuspension study, to reach a viscosity of 5.4 mPa·s only 1.76 percent K 90 was needed instead of 9.5 percent K 30.

The chains are arranged irregularly and the substance is amorphous; it does not show a distinct crystalline melting point. Instead it has a glass transition temperature; for K 90 about 176 °C is reported for Kollidon 90 Evo and 174 °C for Agrimer 90. In one study 156 °C was found.

The glass transition temperature rises with chain length. In the same study 138 °C was measured for K 17, 149 °C for K 30 and 156 °C for K 90. Moisture lowers this temperature markedly.

The binding of water by the carbonyl groups is the reason the substance is hygroscopic. At ambient humidity the polymer absorbs water, is plasticized, and its glass transition temperature falls. An Agrimer document states that the equilibrium moisture is about one third of the relative humidity.

The polymerization product may contain small amounts of by-products such as 2-pyrrolidone, formic acid and aldehyde, as well as residual N-vinylpyrrolidone. Limits for these components are defined in the pharmacopoeias.

The tertiary carbon–hydrogen bonds next to the nitrogen are sensitive to oxygen. During storage, hydroperoxides may form at these sites; for this reason a peroxide limit has been set and oxygen-barrier packaging has been developed. For Kollidon 90 Evo, BASF uses PeroXeal packaging that is filled with inert gas and has an oxygen barrier.

Under the action of a strong acid or base at high temperature, the amide bond may be hydrolyzed and the ring opened. Strong oxidizers shorten the chain or form by-products; therefore compatibility with oxidizing substances is important in use.

The calculated solubility parameter is in the range of about 22–23 MPa½. Good miscibility is expected with active ingredients and solvents whose parameters are close to this value; this property is exploited in amorphous solid dispersions.

PHYSICAL AND CHEMICAL PROPERTIES OF POLYVINYLPYRROLIDONE K 90

General technical specifications:

The values below were compiled from the data sheets, SDSs and pharmacopoeial monographs of different manufacturers. They vary with the measurement method, the manufacturer and the grade; the list provides general information and does not replace manufacturer-specific TDS and SDS documents.

Physical appearance: White to slightly yellowish, odorless or very faintly odorous, hygroscopic powder; the particles are larger than those of K 30 and the flow properties are weaker

Chemical character: Non-ionic, amorphous, linear vinylpyrrolidone polymer; soluble in water and polar solvents

Molecular formula: (C₆H₉NO)ₙ

Molecular weight: 111.14 g/mol for the repeat unit; weight-average molecular weight 900,000–1,200,000 for Kollidon 90 Evo, about 1,200,000 for Luviskol K 90, about 1,300,000 for Plasdone K-90, 1,000,000–1,700,000 for Agrimer 90; 360,000 on some catalogue labels

CAS No: 9003-39-8

EC / EINECS No: There is no single number for the polymer; some documents show 201-800-4, the number of the monomer

K-value: Nominal 90. Pharmacopoeial range 81.0–97.2; 88.0–96.0 is given for Luviskol K 90 (1 percent aqueous solution), 85–95 for Plasdone K-90 and 90–100 for Agrimer 90

Purity (assay): Defined by the nitrogen content on the dry basis; the pharmacopoeial limit is 11.5–12.8 percent, and 12.0–12.8 is given for one laboratory product. For Luviskol K 90 powder the solids content is 95.0–100.0 percent

Density: One SDS reports a specific gravity of 1.23–1.29; this value is the density of the polymer itself, not the bulk state of the powder

Bulk density: 390–500 g/L for Kollidon 90 Evo, 450–600 g/L in the tapped state; 0.4–0.6 g/cm³ is given in one SDS. These values are characteristic and are not specifications

Viscosity: High. In an Agrimer document the Brookfield viscosity of a solution with 5 percent solids at 25 °C appears at about 150 cP; for a 20 percent solution of Luviskol K 90 powder, 10,000–30,000 mPa·s is given at 23 °C. Viscosity rises rapidly with concentration

Solubility in water: Very good; BASF reports a solubility above 10 g/L in water, and 100 mg/mL is stated in one catalogue entry. It also dissolves in ethanol, methanol, isopropanol, glycerol, propylene glycol, PEG 300/400, chloroform and methylene chloride; it does not dissolve in cyclohexane, pentane, ether, ethyl acetate, toluene, xylene and liquid paraffin

pH (aqueous solution): Depends on the concentration and the standard. For a 5 percent solution the European Pharmacopoeia and some suppliers give 4.0–7.0; 3.0–7.0 appears at one supplier. For Luviskol K 90, 5.0–9.0 is reported in a 10 percent solution, and in one SDS 5.0–9.0 in a 5 percent solution

Glass transition temperature: About 176 °C for Kollidon 90 Evo (DSC, second heating), 174 °C for Agrimer 90; 156 °C was found in one study. This value falls markedly as moisture increases

Decomposition: Softens gradually on heating; decomposition above about 200 °C is reported for the polyvinylpyrrolidone family, and the grade-specific limit should be taken from the manufacturer’s document. Decomposition products are carbon oxides and nitrogen oxides

Moisture: At most 5 percent in the pharmacopoeias; because the product is hygroscopic, moisture increases in open packaging. An Agrimer document states that the equilibrium moisture is about one third of the relative humidity

Heavy metals (Pb, Cu, etc.): Heavy metals at most 10 ppm in the pharmacopoeias and lead at most 10 ppm in the USP; EU food additive specifications give at most 2 mg/kg for lead

Residual monomer and impurities: In the Ph.Eur., N-vinylpyrrolidone at most 10 ppm, hydrazine at most 1 ppm, peroxide at most 400 ppm as hydrogen peroxide, aldehyde at most 500 ppm, 2-pyrrolidone at most 3 percent, formic acid at most 0.5 percent and sulfated ash at most 0.1 percent. For Luviskol K 90 powder, at most 100 ppm is given for residual vinylpyrrolidone

Particle size: For Kollidon 90 Evo, d(0.5) of 140–240 µm, d(0.1) of 50–120 µm and d(0.9) of 270–420 µm by laser diffraction; by sieving, at most 10 percent below 50 µm and 5–27 percent above 250 µm. These values are characteristic, not specifications

Reactivity: Stable under normal conditions. Incompatible with strong oxidizers; prone to peroxide formation and moisture uptake during storage; as a fine powder it may form combustible dust

Brief Explanation of Physical Properties

The K 90 grade is distinguished by the consistency of its solution, owing to its very long chains. At the same concentration a K 30 solution is as fluid as water, while a K 90 solution is markedly thicker; for this reason much lower concentrations are generally used in practice, and for wet granulation solutions BASF mentions a range of 1–12 percent.

The fact that molecular weight figures differ from source to source is not a contradiction but a difference in measurement method. Weight-average, number-average and viscosity-average values come out very different from one another for the same polymer. For this reason catalogue labels such as 360,000 and the BASF or Ashland figures should not be read as the same measure.

The angle of repose of Kollidon 90 Evo is 37–40°, the flow rate is 1–2 g/s for a 100 g sample and the compressibility is 7–8 percent. These values show markedly weaker flow than K 30; for this reason powder flow should be tested separately in the hopper, feeding and mixing steps.

The high glass transition temperature provides stability in amorphous solid dispersions. The same high value makes hot-melt extrusion difficult; in one study K 17 could be extruded, while K 30 and K 90 could not be processed because of torque and pressure.

The differences between data sheets mostly come from the grade, the measurement condition and the production method. Pharmacopoeial limits are binding lower and upper values; the manufacturer’s typical values, on the other hand, are informational and should be evaluated together with the batch certificate of analysis.

HOW DOES POLYVINYLPYRROLIDONE K 90 WORK AT THE MOLECULAR LEVEL?

The action of Polyvinylpyrrolidone K 90 rests largely on the ability of the carbonyl oxygen in the pyrrolidone ring to form hydrogen bonds, and on the great length of the chain. The carbonyl groups bond with water, alcohols, phenols and carboxylic acids; the apolar backbone of the chain helps it adhere to surfaces.

In solution, above a certain concentration the chains become entangled and form a temporary network. The longer the chain, the earlier the entanglement begins; this is why K 90 gives high viscosity at low concentration. This property is used for consistency, tack and suspension stability.

As a tablet binder, the polymer dissolved in the granulation liquid wets the surface of the powder particles. During drying the solvent leaves; the long chains form a strong film bridge between the particles and adhere by hydrogen bonds to fillers such as lactose or cellulose. BASF states that the binding power of K 25 and K 30 is weaker than that of Kollidon 90 Evo.

In poorly soluble active ingredients the polymer acts as a matrix that retards crystallization. The high molecular weight slows nucleation and crystal growth through increased viscosity and reduced molecular mobility. In a griseofulvin study K 90 kept the active ingredient amorphous even at a 40 percent load.

This effect does not always go in the same direction for every active ingredient. In a celecoxib study the low-molecular-weight polymer gave faster dissolution, and the benefit of inhibiting crystallization was found to be highest around K 30. For this reason the highest K-value does not always mean the best result.

In suspensions the long chains attach to the surface of solid particles. The loops extending from the surface into the solution prevent the particles from approaching one another; the viscosity of the solution, in turn, slows sedimentation. An Agrimer document states that in crop protection suspensions K 90 or K 120 provides stability through these two effects.

In nanosuspensions the polymer adsorbs weakly to the surface and the result varies with the active ingredient. In one study the average size was 289 nm with K 90 and 189 nm with K 30 for nifedipine; for fenofibrate 373 nm and 272 nm, respectively, were found, and for indomethacin 163 nm and 176 nm were measured.

In the synthesis of metal nanoparticles and nanowires, the oxygen and nitrogen of the pyrrolidone ring coordinate with the metal surface. The polymer binds more strongly to some crystal faces and directs growth in one direction. In a silver nanowire study, wires 132 nm in diameter and 69.9 µm in length were obtained with a polymer of 360,000 weight.

In membrane production, the high-molecular-weight K 90 behaves like a permanent hydrophilic component inside the polyethersulfone structure. The low-molecular-weight K 17, on the other hand, forms pores during precipitation and is largely washed out. In one study K 90 increased the hydrophilicity of the surface.

In film formation, as the solvent evaporates the chains become entangled and form a transparent, hard network. The film that takes up water softens and becomes tacky again; this is the reason for adhesion in the glue stick and for loss of hold in humidity in hair products.

The sensitivity of the carbons next to the nitrogen in the chain to oxidation is the molecular-level reason for hydroperoxide formation during storage. The peroxides formed can damage sensitive active ingredients in pharmaceuticals and food; for this reason it is decisive in the choice of grade.

IN WHICH SECTORS IS POLYVINYLPYRROLIDONE K 90 USED?

Owing to its high molecular weight, its non-ionic character and its solubility in water, it is used in fields that need consistency, adhesion and binding. The main sectors and functions are given below.

Pharmaceuticals

It is used as a tablet and granule binder, a crystallization retarder in poorly soluble active ingredients, a film former, a pore former, a solubilizer and a viscosity modifier. It is an adhesive excipient in oral, topical and ophthalmic products and in transdermal systems and gels.

Cosmetics and personal care

It is a styling polymer that gives strong hold and high viscosity in hair gels, wet-look gels, mousses, pump sprays and liquid styling preparations. It is also used in some oil-based and oil-free creams.

Adhesives

It is a binder that provides strong initial tack and good adhesion to paper in glue sticks and remoistenable systems. Ashland offers the K-90 grade as designed for adhesive applications.

Agriculture

In crop protection suspensions it provides viscosity and steric hindrance for stability, and it serves as a binder in water-dispersible granules. It is also mentioned as a carrier for pheromones and attractants.

Membranes and filtration

It is a high-molecular-weight hydrophilizing additive added to the casting solution of membranes such as polyethersulfone; it improves the wettability of the surface.

Nanomaterial synthesis

It is a surface coating agent that directs the lengthwise growth of silver nanowires and stabilizes them; a high molecular weight gives longer and thinner wires.

Electrospinning and fiber production

It provides the chain entanglement needed to obtain nanofibers by electrospinning from solvents such as ethanol; it is the carrier polymer in fast-dissolving drug-loaded fibers.

Laboratory and biotechnology

It is a component of Denhardt’s solution and is used as a surface coating agent in hydroxyapatite nanoparticles. In media used for ICSI in assisted reproduction laboratories it is present at 7 and 10 percent; it slows sperm motility and prevents sticking to the pipette.

Food and beverages

Use is very limited. E 1201 is an additive permitted only in certain food supplement tablets and sweetener tablets; for clarifying beer and wine, cross-linked PVPP is used, not soluble PVP.

For each of these fields the grade, documentation and regulatory compliance should be evaluated separately.

IS POLYVINYLPYRROLIDONE K 90 USED IN COSMETIC, FOOD AND PHARMACEUTICAL APPLICATIONS?

Cosmetic applications

Yes. It is known as PVP in cosmetics; the main use of products such as Luviskol K 90 is hair styling. In hair gels, creams, mousses, pump sprays and liquid styling preparations it gives strong hold and high viscosity as a styling polymer and thickener.

Its 20 percent solutions are used in wet-look gels. The manufacturer’s document states that the product is also found in some oil-based and oil-free creams.

The Cosmetic Ingredient Review (CIR) has found vinylpyrrolidone polymers safe for cosmetic use. Even so, product-based safety assessment, the residual monomer limit and the legislation on the final product are the manufacturer’s responsibility.

Because it is hygroscopic, hold on the hair may decrease in humid air; for this reason it is also used together with vinyl acetate copolymers or carbomer for moisture resistance. Because of the high viscosity, low concentrations are sufficient.

Food applications

To a limited extent. Polyvinylpyrrolidone is registered in the EU as a food additive under the code E 1201; however, the permitted use is limited to food supplement tablets and sweetener tablets. It cannot be added directly to every food.

The EFSA concluded in its 2020 assessment that an acceptable daily intake value is not needed; JECFA, on the other hand, set a value of 0–50 mg/kg body weight in 1986. Quality, residual monomer and impurity limits are defined in the additive specifications.

The substance used for clarification in beer and wine is the insoluble PVPP, known by the code E 1202. It is used as a processing aid and prevents haze by binding phenolic compounds; it is not the same substance as soluble povidone such as K 90.

Pharmaceutical applications

Yes. High-molecular-weight povidone is among the grades that have a pharmacopoeial monograph, and BASF offers this grade as a pharmaceutical excipient under the name Kollidon 90 Evo. It is a binder in tablets and granules, a film former in coating, and a solubilizer and viscosity modifier in various products.

BASF gives the typical binder level in wet granulation as 1–5 percent; examples include 1.5 percent in microcrystalline cellulose, 2.5 percent in dicalcium phosphate and 2.5 percent for metformin in a fluid bed. In one study, among the Kollidon grades compared for eye drops, a 5 percent Kollidon 90 solution stood out as the option giving thickening and retention at the lowest concentration.

The nitrite level is important for sensitive active ingredients; no nitrite was detected in Kollidon 90 Evo (limit of determination 0.7 ppm). Administration of high-molecular-weight grades by injection is not considered appropriate. Povidone allergy is rare.

The use of a chemical in one sector does not mean that it can be used in other sectors. For pharmaceutical, food and cosmetic applications the grade, documents and legal conditions should be verified separately with the supplier.

INDUSTRIAL APPLICATIONS OF POLYVINYLPYRROLIDONE K 90

Its industrial value lies in its high viscosity and strong binding even at low concentrations, its solubility in water and its compatibility with many substances. The headings below describe the function, the reasons for preference and the limits for each application.

Tablet and granule production

As a binder in wet granulation the typical level is 1–5 percent. BASF examples include 1.5 percent in microcrystalline cellulose, 2.5 percent in dicalcium phosphate and 2.5 percent for metformin in a fluid bed. Binder solutions are prepared at a concentration of 1–12 percent; in a fluid bed it is mostly kept below 7 percent solids.

Because of the high viscosity, pumping and spraying the solution is harder than with K 30; for this reason a low concentration is chosen. Alternatives are K 30, hydroxypropyl cellulose, copovidone and hypromellose.

Amorphous solid dispersion and crystallization retardation

In a griseofulvin study K 17 (about 9,000), K 30 (50,000) and K 90 (1,250,000) were compared. Their glass transition temperatures are 138, 149 and 156 °C, respectively. When K 90 was processed by KinetiSol, a high-shear fusion method, it kept the active ingredient amorphous at a 40 percent load.

In the same study hot-melt extrusion was possible only with K 17 and hypromellose E5; K 30 and K 90 could not be extruded because of torque and pressure. A long chain length slows crystallization, but it limits processability.

Fast-dissolving electrospun fibers

In one study PVP K 90 was dissolved in ethanol at a concentration of 10 percent (w/v) and electrospun together with paracetamol and caffeine. The conditions were 15 kV, 1.2 mL/h, a distance of 12 cm, a 20 G needle, 22 °C and 35 percent relative humidity. Fiber diameters were found to lie between 443 and 1553 nm depending on the active ingredient load.

The fibers released 38–66 percent of the paracetamol and 52–72 percent of the caffeine in 30 seconds; in a physical mixture of the same composition these figures stayed at 4.5 and 37 percent. Some fibers disintegrated in simulated saliva in about 320 milliseconds.

Nanosuspension stabilizer

Nanosuspensions of nifedipine, fenofibrate and indomethacin were prepared by wet milling, and for the same viscosity (5.4 mPa·s) 9.5 percent K 30 or 1.76 percent K 90 was used. The target criterion is that the average size stays below 500 nm and the polydispersity index below 0.3.

K 90 did not meet the criterion for fenofibrate (373 nm, index 0.31) and showed aggregation for indomethacin at pH 1.2. The authors found the most robust result with the combination of 4 percent hydroxypropyl cellulose and 0.2 percent dioctyl sulfosuccinate.

Eye drops and thickening

The soluble Kollidon grades (17, 25, 30, 90 and VA 64) were compared as eye drop thickeners in terms of density, pH, viscosity and transparency. A 5 percent Kollidon 90 solution stood out as the option giving the necessary thickening and retention at the lowest concentration.

The summary of the study gives no numerical viscosity values. Alternatives are hypromellose, carboxymethyl cellulose and polyvinyl alcohol; sterile grade, preservative and regulatory conditions are evaluated separately for each product.

Hair styling

Luviskol K 90 gives strong hold and high viscosity in hair gels, mousses, pump sprays and liquid styling preparations. Its 20 percent solutions are used in wet-look gels.

Because of the high viscosity, lower concentrations than with K 30 are sufficient. For loss of hold in humidity, use together with a vinyl acetate copolymer or carbomer is evaluated; because of the tendency to bind with basic dyes, compatibility must be tested in colored products.

Adhesives

The 20 percent solution of Luvitec K 90 provides strong initial tack and good adhesion to paper in glue sticks. Ashland offers the K-90 grade as designed for adhesive applications; the polymer is hygroscopic and amorphous and can be plasticized with water.

Because the film may soften and stay tacky in a humid environment, storage conditions are important. Alternatives are K 30, polyvinyl alcohol, dextrin and acrylic dispersions.

Agriculture and crop protection

According to the Agrimer document, high-molecular-weight grades build viscosity faster and are successful in binding and film formation. It is used as a carrier for pheromones and attractants.

For suspension stability, K 90 or K 120 provides steric hindrance and a viscosity effect. In water-dispersible granules containing herbicides, K 30 and K 90 are binders; an auxiliary disintegrant contributes to the dispersion of the granule in water.

Membranes and filtration

The high-molecular-weight K 90 added to the casting solution of polyethersulfone membranes increases the hydrophilicity of the surface. The low-molecular-weight K 17, on the other hand, is used as a pore former and increased pure water permeability up to 5 percent.

K 90 reduced permeability above 3 percent; for this reason the level is kept limited. The washing-out of the polymer from the membrane should be monitored, and polyethylene glycol and other hydrophilic polymers should be evaluated as alternatives.

Silver nanowire synthesis

In the polyol method it is a surface coating agent and stabilizer. In one study a polymer of 10,000 weight gave only particles, a polymer of 58,000 weight gave wires 235 nm in diameter and 6.7 µm in length, and a polymer of 360,000 weight gave wires 132 nm in diameter and 69.9 µm in length.

A mixture of PVP 40,000 and PVP 360,000 (1:1) gave the best result with an aspect ratio of about 1000. Another study comparing four weights, including 1,300,000, reports that a high weight gave longer and thinner wires. The coating polymer may require washing after synthesis.

Battery electrodes and carbon nanotube dispersion

In one industry source, K 25 and K 30 grades gave lower resistance and more homogeneous dispersion in multi-walled nanotubes than K 17 and K 90. In this field K 90 is mostly not the first choice.

Because the viscosity increase can make slurry processing harder, the K-value should be tested on an application basis when choosing a dispersant. Alternatives are K 25, K 30, PVDF and carboxymethyl cellulose.

Laboratory and biotechnology

It is a component of Denhardt’s solution; a catalogue gives a level of 1 percent (w/v) in the 50X stock. It is also used as a coating agent on the surface of hydroxyapatite nanoparticles; a type whose average weight is stated as 360,000 appears in the catalogue.

In ICSI media in assisted reproduction laboratories, 7 and 10 percent solutions are used; the medium slows sperm motility and prevents sticking to the pipette. These media are ready-made laboratory products produced specially. In one study hyaluronate also performed a similar function.

CONSIDERATIONS IN THE USE OF POLYVINYLPYRROLIDONE K 90

Polyvinylpyrrolidone K 90 is a polymer that is widely regarded as non-hazardous but that requires attention in terms of quality, viscosity and handling. The main points to be taken into account in use:

•    The K-value must be written correctly: an order should not be placed with the polymer name alone; the required grade and range, such as K 90, should be stated clearly; the K 90 ranges of different manufacturers differ from one another, and confusion with neighboring grades such as K 30 and K 120 must also be avoided

•    The grade should be determined according to the application: pharmaceutical, food, cosmetic and technical grades differ in residual monomer, peroxide and impurity limits; 100 ppm is given for residual vinylpyrrolidone for Luviskol K 90 and 10 ppm in the pharmacopoeia

•    The product must be protected from moisture: because it is hygroscopic it takes up water in an opened package, cakes and its glass transition temperature falls; the package must be closed immediately after use

•    When preparing a solution, the powder should be added slowly under stirring: in a long-chain grade, if the powder is added quickly, lumps that gel on the surface form and dissolution takes longer than with K 30; warm water may speed up dissolution

•    Viscosity must be taken into account: because a 20 percent solution can give 10,000–30,000 mPa·s, pump, dosing and spraying equipment must be chosen accordingly, and limits such as the concentrations below 7 percent solids that BASF gives for a fluid bed must be observed

•    Peroxide formation must be taken into account: peroxides may increase during storage; BASF states that for Kollidon 90 Evo the protection ends when the package is first opened, and recommends reclosing, fast consumption and peroxide monitoring

•    The choice of additives can change the results: in one study ascorbic acid was found to increase the peroxide effect, while propyl gallate and EDTA reduced oxidative degradation; compatibility should be tested separately in each formula

•    It must not be used together with strong oxidizers and strong bases: oxidizers degrade the chain and may form by-products; for this reason the product must be kept away from such substances

•    Aqueous solutions are open to microbial growth: for solutions to be kept, a preservative must be used or the solution must be prepared fresh; mold is reported to form in acidic and dilute solutions

•    Compatibility with anionic polymers must be tested: when used together with anionic polymers such as carbomer, the pH and the order of addition may affect clarity and consistency

•    Dust accumulation must be prevented: fine dust can form a combustible dust mixture in air; sparks and sources of static electricity must be avoided, equipment must be grounded, and cleaning with compressed air must not be done

•    Dust must not be inhaled and contact with the eyes must be avoided. Dust may be irritating; safety goggles, gloves and suitable respiratory protection where dust is generated must be used

•    Environmental impact must be taken into account. The polymer is not readily biodegradable, but it is not considered harmful to aquatic organisms in SDSs; solutions and waste must be disposed of according to local legislation

•    The regulatory status must be verified. For pharmaceutical, food, cosmetic and contact-material uses, the declaration of conformity and the level of documentation must be checked separately

This information is for general information purposes; it does not replace product-specific SDS and TDS documents.

INITIAL FORMULATION APPROACHES FOR POLYVINYLPYRROLIDONE K 90

The approaches in this section are short starting examples showing how the product can be evaluated in the fields of fast-dissolving fibers, nanosuspensions and membranes. Since Polyvinylpyrrolidone K 90 is a low-risk polymer, the levels are given as approximate percentages.

The examples are not verified commercial recipes, production instructions or final formulas that comply with legislation. The levels are starting points for preliminary laboratory trials, and the total of each formula is 100 percent. The electrospinning conditions and the equal-viscosity ratio were taken from literature studies; the other levels are general practice values.

The result varies with the active ingredient and other components used, with the molecular weight of the polymer, with pH, temperature and humidity conditions. In every application, technical evaluation, quality and regulatory checks must be carried out, and the levels must be reviewed by specialists.

EXAMPLE 1: ASSESSMENT OF THE EFFECT OF THE ACTIVE INGREDIENT LOAD ON FIBER DIAMETER AND RELEASE RATE IN FAST-DISSOLVING ELECTROSPUN FIBERS

Purpose: To monitor how fiber diameter and release in the first 30 seconds change as the active ingredient load increases in fibers carried by Polyvinylpyrrolidone K 90.

Starting approach (on a fiber solids basis):
Polyvinylpyrrolidone K 90: about 75.2 percent
Paracetamol (model active ingredient): about 21.9 percent
Caffeine (model active ingredient): about 2.9 percent

Application approach:
•    The polymer is dissolved in anhydrous ethanol at a concentration of about 10 percent (w/v); the active ingredients are dissolved separately in a small amount of ethanol and added to the polymer solution.
•    The solution is spun from a syringe with a 20 G needle at 1.2 mL/h, at a voltage of 15 kV and a distance of 12 cm onto a collector; 22 °C and about 35 percent relative humidity were used in the literature.
•    It is observed that the fiber diameter grows as the active ingredient load is increased; the diameter is measured by scanning electron microscopy.
•    Release is measured over short periods such as 30 seconds and compared with a physical mixture of the same composition.
•    In the study in the literature, a PVP K 90 whose average weight is stated as 360,000 was used; with a polymer of a different weight the concentration and conditions must be re-tested.
•    Ethanol is flammable and high voltage is used; an apparatus that is away from ignition sources, grounded and ventilated is required.

EXAMPLE 2: ASSESSMENT OF THE EFFECT OF THE POLYMER STABILIZER GRADE ON PARTICLE SIZE AND REDISPERSION IN A NANOSUSPENSION

Purpose: To compare the effect of Polyvinylpyrrolidone K 90 on average particle size, size distribution and redispersion with that of K 30 in a nanosuspension prepared by wet milling.

Starting approach:
Model active ingredient (poorly soluble in water): about 5.0 percent
Polyvinylpyrrolidone K 90: about 1.8 percent
Wetting agent (sodium dioctyl sulfosuccinate): about 0.2 percent
Purified water: about 93.0 percent

Application approach:
•    The polymer and the wetting agent are dissolved in water; the active ingredient is added, pre-dispersion is carried out and wet milling is applied in a bead mill.
•    For comparison the viscosity is equalized; in the literature about 9.5 percent K 30 or 1.76 percent K 90 (w/v) was used for 5.4 mPa·s.
•    The average size and polydispersity index are measured; the acceptance criterion is below 500 nm and below 0.3.
•    Redispersion and aggregation are monitored at pH 1.2 and pH 6.8.
•    Because K 90 gives larger particles than K 30 with some active ingredients, it is also compared with polymers such as hydroxypropyl cellulose and with wetting agent combinations.
•    A dust mask, goggles and gloves are used for the powder active ingredient and the milling medium.

EXAMPLE 3: ASSESSMENT OF THE EFFECT OF THE POLYMER LEVEL ON PERMEABILITY AND WETTABILITY IN A HYDROPHILIC POLYETHERSULFONE MEMBRANE CASTING SOLUTION

Purpose: To monitor the effect of the level of Polyvinylpyrrolidone K 90 in a polyethersulfone casting solution on solution viscosity, pure water permeability and surface wettability.

Starting approach:
Polyethersulfone: about 16.0 percent
Polyvinylpyrrolidone K 90: about 2.0 percent
Polar aprotic solvent (for example N-methyl-2-pyrrolidone or dimethylacetamide): about 82.0 percent

Application approach:
•    The polyethersulfone is dissolved in the solvent by heating and stirring; the polymer is added and the solution is left to stand until air bubbles are removed.
•    The solution is cast on a glass plate at a constant thickness, precipitated in a water bath and the membrane is washed.
•    The K 90 level is kept below about 3 percent; in one study permeability fell above this level. K 17, on the other hand, increased permeability up to 5 percent; a mixture of the two grades can also be tried.
•    The viscosity of the casting solution, pure water permeability, contact angle and the retention of the polymer in the membrane are compared.
•    The use of the solvents is subject to strict regulatory conditions in the EU; compliance should be checked, and gloves, goggles and ventilation should be used.

SIMILAR PRODUCTS AND ALTERNATIVES TO POLYVINYLPYRROLIDONE K 90

When determining an alternative, function, solubility, moisture behavior, film properties, regulation and cost should be evaluated together; the aim is not merely to choose another polymer.

POLYVINYLPYRROLIDONE K 90 AND POLYVINYLPYRROLIDONE K 30

K 30 has much shorter chains; its solution is fluid, it dissolves quickly and is easy to process. Its binding power and adhesion strength are lower than those of K 90; BASF describes the binding performance of K 25 and K 30 as weaker than that of Kollidon 90 Evo.

In one study, 9.5 percent K 30 or 1.76 percent K 90 was required to give the same viscosity. In operations such as granulation liquid and spraying K 30 is chosen more often, and in the role of tack and consistency enhancer K 90.

POLYVINYLPYRROLIDONE K 90 AND LOW K-VALUE GRADES (K 12, K 17)

Low K-value grades have very short chains; their solutions are as fluid as water and their films are brittle. They are preferred in applications such as povidone-iodine and pore formation; in polyethersulfone membranes K 17 increases permeability while K 90 increases wettability.

The two grades can take on different roles in the same formula. K 17 helps to open pores, while K 90 helps to form a permanent hydrophilic surface and to give consistency.

POLYVINYLPYRROLIDONE K 90 AND POLYVINYLPYRROLIDONE K 120

K 120 has even longer chains and gives a more viscous solution. The Agrimer document states that the 60, 90 and 120 grades markedly affect flow properties, and that K 90 and K 120 are mentioned together for suspension stability.

Dissolving and processing the longer chain is harder. The choice of grade should be made by trials according to the target viscosity and the processing equipment.

POLYVINYLPYRROLIDONE K 90 AND COPOVIDONE

Copovidone is a copolymer made up of vinylpyrrolidone and vinyl acetate units and is sold under names such as Kollidon VA 64 and Luviskol VA. Manufacturers state that, compared with povidone, it is less hygroscopic, more plastic and has a lower glass transition temperature.

These properties are an advantage for hot-melt extrusion, tablet compression and hair hold in humid environments. K 90 caused torque and pressure problems in hot-melt extrusion; in systems that need high consistency and binding, on the other hand, K 90 stands out.

POLYVINYLPYRROLIDONE K 90 AND POLYVINYL ALCOHOL

Polyvinyl alcohol is also a water-soluble, film-forming and adhesive polymer. It generally gives higher mechanical strength and barrier properties; its dissolution may require heating.

In adhesives and coatings the two polymers are used together: polyvinyl alcohol provides adhesion, while K 90 provides wetting and initial tack. Pure polyvinyl alcohol does not take the place of the complex-forming and crystallization-retarding function of K 90.

POLYVINYLPYRROLIDONE K 90 AND CELLULOSE DERIVATIVES

Hypromellose (HPMC) and hydroxypropyl cellulose (HPC) are cellulose ethers used as tablet binders, film coatings and gel formers. They can swell in water to form gel structures and slow-release matrices.

K 90 provides fast binding and strong adhesion, while cellulose derivatives are less hygroscopic and suitable for controlled release. In the nanosuspension study the combination of HPC and dioctyl sulfosuccinate was found to be more robust than K 90; the choice varies with the active ingredient.

POLYVINYLPYRROLIDONE K 90 AND OTHER THICKENING POLYMERS

Carbomer and xanthan gum are thickeners that give high viscosity at low concentration. The former is anionic and depends on pH and neutralization; the latter is of natural origin and shows shear thinning.

K 90 is a non-ionic polymer that gives a clear solution; it also provides binding and film formation. Carbomer and K 90 can be used together in the same gel, but putting one in place of the other changes performance.

POLYVINYLPYRROLIDONE K 90 AND CROSPOVIDONE

Crospovidone is the cross-linked, water-insoluble PVPP. It is a disintegrant that swells in water and disperses tablets rapidly; it also holds polyphenols in beer and wine and prevents haze.

It does not show the binding, consistency-giving and film-forming functions of soluble K 90. For this reason the two substances can be present in the same formula but do not replace one another.

POLYVINYLPYRROLIDONE K 90 AND VINYLPYRROLIDONE COPOLYMERS

Copolymers of vinylpyrrolidone with monomers such as vinylimidazole, vinyl acetate or dimethylaminoethyl methacrylate acquire special functions according to the intended use. They are used in hair care and cationic care products.

No alternative is a one-to-one substitute in every system. In every case performance testing and regulatory checks must be carried out, and the K-value and grade must be evaluated together.

QUALITY CONTROL AND PURCHASING CRITERIA FOR POLYVINYLPYRROLIDONE K 90

Polyvinylpyrrolidone products sold under the same CAS number differ from one another in K-value, grade, moisture, residual monomer and peroxide level. For this reason, for K 90 it should first be clarified whether the product is of pharmaceutical, food, cosmetic or technical grade.

The main parameters that can be evaluated in quality control and the purchasing process:

•    K-value: The measured value is compared with the nominal value of 90 on the label. The Ph.Eur. and USP define the acceptance range as 90–108 percent of the nominal value, which comes to 81.0–97.2. Supplier ranges vary: 88.0–96.0 for Luviskol K 90, 85–95 for Plasdone K-90, 90–100 for Agrimer 90 and 84.0–95.0 for one laboratory product

•    Molecular weight: Manufacturers give ranges of roughly 900,000–1,200,000 (BASF), roughly 1,200,000 (Luviskol), roughly 1,300,000 (Plasdone) or 1,000,000–1,700,000 (Agrimer) for K 90. Some catalogue labels show 360,000; the measurement method and the type of average should be asked about, and the K-value should be taken as the binding value for the target application

•    Nitrogen content: On the dry basis the pharmacopoeial limit is 11.5–12.8 percent; 12.0–12.8 is given for one laboratory product. The method and the range should be clarified with the supplier

•    Moisture: At most 5 percent in the pharmacopoeias; the solids content of Luviskol K 90 powder is 95.0–100.0 percent. Because the product is hygroscopic, the moisture of the batch at delivery and after opening should be asked about separately

•    Residual monomer: The Ph.Eur. and USP limit for N-vinylpyrrolidone is at most 10 ppm. At most 100 ppm is given for Luviskol K 90; the limit should be requested in writing before ordering

•    Peroxide: A limit of at most 400 ppm as hydrogen peroxide is defined. Low-peroxide grades and oxygen-barrier packaging are available for active ingredients sensitive to oxidation; the batch result should be verified from the certificate of analysis

•    Aldehyde, hydrazine and other impurities: Aldehyde is defined as about 500 ppm (0.05 percent in the USP), hydrazine at most 1 ppm, 2-pyrrolidone at most 3 percent and formic acid at most 0.5 percent

•    Sulfated ash and heavy metals: Sulfated ash at most 0.1 percent and heavy metals at most 10 ppm. EU food additive specifications give at most 2 mg/kg for lead

•    pH: In a 5 percent solution the Ph.Eur. and some suppliers give 4.0–7.0. For Luviskol K 90 wider ranges such as 5.0–9.0 appear for a 10 percent solution; values should not be compared without knowing the measurement concentration

•    Nitrite: Important when used with sensitive active ingredients. No nitrite was detected in Kollidon 90 Evo (limit of determination 0.7 ppm); a value should be requested for other grades

•    Microbiological quality: In one supplier specification the total aerobic viable count is at most 200 CFU/g and yeast and mold at most 20 CFU/g. In pharmaceutical and cosmetic use these limits should be looked for in the document

•    Appearance: It should be a white to slightly yellowish powder. Caking, darkening or moisture stains point to a quality problem

•    Particle size and bulk density: BASF gives the bulk density of Kollidon 90 Evo as 390–500 g/L and d(0.5) by laser diffraction as 140–240 µm; these are characteristic values, not specifications. Coarse particles can affect dissolution

•    Viscosity: A 20 percent solution of Luviskol K 90 powder gives 10,000–30,000 mPa·s at 23 °C by Brookfield. Because viscosity is very sensitive to concentration, temperature and measurement condition, the spindle and speed information should also be requested

•    Grade types: The same manufacturer may offer pharmaceutical (Kollidon 90 Evo), cosmetic (Luviskol K 90) and technical (Luvitec K 90) grades; which type is required should be written clearly in the order

•    Documents: Batch-based certificate of analysis, current SDS, TDS, pharmacopoeial compliance (Ph.Eur., USP, JP), declaration of conformity with food additive specifications, REACH information and, where necessary, pharmaceutical excipient quality documents

•    Packaging and batch: For Kollidon 90 Evo, BASF gives a 50 kg square fiber drum and a 0.5 kg plastic pail sample pack; small packs are available in laboratory quantities. The batch number and production date should be checked

•    Shelf life: 36 months from the production date is given for Kollidon 90 Evo and 36 months in the original closed package for Luviskol K 90 powder. The moisture and peroxide level of a product that has been held for a long time can be retested before use

Binding specifications and typical values should be kept apart. Typical values are for information; the specification in the contract and the batch results on the certificate of analysis should be taken as the basis.

STORAGE AND TRANSPORT OF POLYVINYLPYRROLIDONE K 90

It is stable in dry, closed packaging; the most important storage factors are moisture, oxygen and heat. Storage conditions should be determined according to these properties.

•    Temperature and place: It is stored in a cool, dry, well-ventilated place away from heat sources and direct sunlight. +10 to +25 °C is recommended for Luviskol K 90, and for one laboratory product a cool, dark environment below 15 °C with inert gas; in some documents room temperature is considered sufficient. The TDS of the grade concerned should be taken as the basis

•    Moisture: The product is hygroscopic; an Agrimer document states that the equilibrium moisture is about one third of the relative humidity. The package should be kept tightly closed, and an opened package should be closed immediately

•    Packaging: It should be stored in its original packaging with the labels intact. For Kollidon 90 Evo, BASF uses PeroXeal packaging with an inert-gas-filled, oxygen-barrier inner liner; the protection ends at first opening

•    Oxygen and peroxide: The peroxide level may rise during long-term storage. BASF recommends reclosing, fast consumption of the product and peroxide monitoring; handling under nitrogen is evaluated for sensitive applications

•    Incompatible substances: It should be stored apart from strong oxidizers and strong bases. It should be kept away from heat sources, flammable materials and ignition sources

•    Dust and fire safety: Fine dust can form a combustible dust mixture in air. Dust accumulation should be prevented, equipment should be grounded and cleaning with compressed air should not be done

•    Stacking: Drums and bags should be stacked in a balanced way, crushing and tearing should be prevented, and damaged packages should be set aside

•    Solutions: Aqueous solutions should be kept in closed containers; if they are to be held, a preservative should be added or the solution should be prepared fresh. In high-viscosity solutions bubbles may form, so holding after preparation may be needed

•    Shelf life: It is 36 months for Kollidon 90 Evo and Luviskol K 90 powder; retest conditions are found in supplier documents

•    Transport: The safety data sheets examined state that the solid product is not regulated as a dangerous good in road, air and sea transport; no UN number or hazard class is assigned

•    Transport classification: Classification may depend on the product form and the date of the document. Solutions, complexes such as povidone-iodine and ready-made mixtures may be assessed differently. Before shipment the supplier’s current SDS and the applicable legislation should be taken as the basis

•    During transport: Package integrity should be preserved, the product should be kept away from moisture and rain, and it should not be loaded together with oxidizing substances

SAFETY INFORMATION ON POLYVINYLPYRROLIDONE K 90

In manufacturers’ safety data sheets, Polyvinylpyrrolidone K 90 is mostly not classified as a hazardous substance. A combustible dust warning appears in two SDSs; statements may differ from supplier to supplier.

The information below is for general information purposes and does not replace the manufacturer-specific safety data sheet. Each supplier’s own SDS should be taken into account.

Main safety topics:

•    Hazard classes: One SDS states that it is not classified as a hazardous substance. A combustible dust warning appears in two documents; one document mentions it as International Agency for Research on Cancer (IARC) Group 3, that is, not classifiable as to carcinogenicity to humans. Classification should be checked according to the grade and the supplier

•    Acute toxicity: The oral LD50 in rats is reported as 100,000 mg/kg in one SDS and above 10,000 mg/kg in another; above 40,000 mg/kg is given in mice. Its widespread use in food and pharmaceuticals is consistent with this low toxicity

•    Skin and eye contact: It generally does not irritate the skin. In case of eye contact, rinse with plenty of water for at least 15 minutes, and seek medical help if irritation continues

•    Inhalation: Dust may irritate the respiratory tract; it is stated that with repeated and prolonged high dust exposure lung tissue may be affected. The person should be taken to fresh air, and medical help should be sought if symptoms continue

•    Ingestion: The mouth should be rinsed, plenty of water should be given, and if discomfort continues a health facility or a poison information center (114 in Türkiye) should be contacted

•    Fire and explosion: It is hard to ignite in bulk; however, a cloud of fine dust can ignite from a spark. In a fire, water spray, alcohol-resistant foam, dry chemical or carbon dioxide is used; combustion products are carbon monoxide, carbon dioxide and nitrogen oxides

•    Reactivity: Stable under the recommended conditions. It is incompatible with strong oxidizers and may react violently; it is hygroscopic

•    Personal protective equipment: Safety goggles, gloves and protective clothing should be used. In places where dust is generated, respiratory protection with a particle filter and local exhaust are recommended

•    Spills: Sweep up without raising dust and collect in a separate container; compressed air should not be used. A wetted polymer makes the surface slippery; after a spill the area should be washed with plenty of water

•    Monomer: The N-vinylpyrrolidone used in production is classified as a category 2 carcinogen. Residual limits are kept low in product grades; workplace limits apply separately in plants that work with the monomer

•    Environment: The polymer is not readily biodegradable; it is not considered harmful to aquatic organisms in SDSs. It should not be released into streams and sewers in high loads

•    Waste: Residual product and contaminated packaging should be disposed of according to local legislation; where appropriate, recycling or controlled incineration is considered

•    Exposure and help: If symptoms continue, or if there is doubt about ingestion, inhalation or eye contact, a health facility should be contacted with the product label and the SDS

WHAT SHOULD BE CONSIDERED WHEN BUYING POLYVINYLPYRROLIDONE K 90?

To choose the right product, the identity must first be clearly established. Polyvinylpyrrolidone can be confused with cross-linked PVPP, copovidone, povidone-iodine and the monomer N-vinylpyrrolidone, and K 90 can be confused with neighboring grades such as K 30, K 60 and K 120.

In a request, the product name Polyvinylpyrrolidone K 90, the CAS number 9003-39-8 and, if needed, a K-value range such as 85–95 or 88.0–96.0 should be stated together.

The main points to pay attention to when buying:

•    Intended use and regulation: It should be clarified whether the product will be used in a pharmaceutical, food, cosmetic or technical application; the regulatory conditions of the country concerned should be verified with the supplier

•    K-value range: The K 90 ranges of manufacturers differ from one another; the accepted lower and upper limits should be determined according to the sensitivity of the application

•    Molecular weight and measurement method: The 360,000 on catalogue labels and the BASF or Ashland figures are different averages; it should be asked by which method and for which average they are given

•    Grade: Between pharmaceutical, food, cosmetic and technical grades there may be differences in residual monomer, peroxide and level of documentation. The cosmetic-grade document may state that it is not suitable for pharmaceutical use

•    Technical specifications: K-value, nitrogen, moisture, residual monomer, peroxide, aldehyde, heavy metals, pH, viscosity and particle size should be requested explicitly

•    Form: The need for powder or an aqueous solution (for example 20 percent) should be stated; dissolution time, dust formation and viscosity depend on this choice

•    Packaging and logistics: Net quantity, moisture-barrier packaging, pallet arrangement and storage conditions should be determined

•    Batch consistency: Certificates of analysis, K-values and physical appearance of consecutive batches should be compared

•    Shelf life: The production date and the remaining shelf life of the delivered product should be asked about

•    Documents: SDS, TDS, COA, pharmacopoeial compliance, REACH information and, where necessary, food and cosmetic declarations of conformity should be requested

•    Supplier’s technical support: Information support on grade selection suited to the application, solution preparation and storage should be evaluated

•    Origin and manufacturer: Transparency of the manufacturer information and traceability may be requested

•    Total cost of supply: Besides the unit price, the K-value, grade, dose, packaging, storage and waste management costs should be calculated together; a low usage level in a high K-value grade can affect the total cost

A price comparison should not be made on the price per kilogram alone; the K-value range, grade, level of documentation and security of supply should also be taken into account.

SUPPLY OF POLYVINYLPYRROLIDONE K 90 FROM ATAMAN KİMYA

Polyvinylpyrrolidone K 90 is a product evaluated as a tablet binder, a crystallization retarder, a styling agent in hair care, a binder in glue sticks, a stabilizer in crop protection suspensions and a hydrophilizing agent in membrane production.

On the ATAMAN KİMYA website, Polyvinylpyrrolidone K 90 appears on product pages under the names Polyvinylpyrrolidone K 90, Polyvinylpyrrolidone K90 (PVP K 90), PVP K 90, PVP K-90, Povidone K90, Povidone K-90, Povidone K 90, Povidone (PVP) K 90 and Polyvinylpyrrolidone (PVP) K 90; in addition, there is a product page in solution form under the name PVP K 90 Solution.

Companies planning to buy are advised to clarify the grade suited to the intended use, the K-value range, the technical specifications, the regulatory conditions and the necessary documents before ordering.

Companies that want information on supply from ATAMAN KİMYA can request information on product suitability, current supply status, packaging options and a price quotation by sharing their fields of use and technical needs.

The current stock status, origin, grade, K-value range, packaging, transport classification and the regulatory conditions for the intended use of the product should be confirmed with ATAMAN KİMYA before ordering.

Sharing the following information in a quotation request makes it easier to evaluate the right product quickly:

•    Field of use and final application

•    Requested product name or grade: Polyvinylpyrrolidone K 90, PVP K90, Povidone K-90 or equivalent

•    Required K-value range

•    Requested form: powder or solution

•    Limits for moisture, residual monomer, peroxide and impurities

•    Grade: pharmaceutical, food, cosmetic or technical

•    Regulatory status for the intended use

•    Process or application method used

•    Estimated order quantity

•    Required packaging type

•    Requested technical documents

•    TDS or COA information of the existing product, if available

FREQUENTLY ASKED QUESTIONS ABOUT POLYVINYLPYRROLIDONE K 90

What is Polyvinylpyrrolidone K 90?
It is the high-molecular-weight grade, with a K-value of about 90, of a water-soluble, non-ionic synthetic polymer made from the N-vinylpyrrolidone monomer. It is used as a strong binder, thickener, tackifier and stabilizer in pharmaceuticals, cosmetics, adhesives and membranes.

What does Polyvinylpyrrolidone K 90 mean?
The name denotes the polymer formed by chaining vinyl units that carry a pyrrolidone ring, and the fact that its K-value is about 90. In pharmacopoeial and regulatory language the same substance appears under the name povidone K 90.

What is the CAS number of Polyvinylpyrrolidone K 90?
The CAS number is 9003-39-8. This number covers all K-values; grades such as K 30 and K 90 are sold under the same number, so the K-value must be stated separately in the order.

What is the EC / EINECS number of Polyvinylpyrrolidone K 90?
There is no single EC number for the polymer. Some documents give 201-800-4, the number of the monomer N-vinylpyrrolidone; the CAS number and the K-value are taken as the basis for identifying the product.

What is the chemical formula of Polyvinylpyrrolidone K 90?
The polymer, whose repeat unit is C₆H₉NO, is written as (C₆H₉NO)ₙ. The molecular weight of the repeat unit is 111.14 g/mol; for K 90 manufacturers give the weight-average molecular weight in the range of about 900,000–1,700,000.

What does the K-value mean in Polyvinylpyrrolidone K 90?
The K-value is a number calculated from the viscosity of the polymer in dilute solution and related to the average molecular weight. For K 90 the acceptance range in the pharmacopoeias is 90–108 percent of the nominal value; that is, about 81.0–97.2.

What is the INCI name of Polyvinylpyrrolidone K 90?
The INCI name is PVP; the K-value is not stated in the INCI name. The existence of an INCI name does not mean that the product can automatically be used in cosmetics; the grade and legal conditions must be evaluated separately.

Is Polyvinylpyrrolidone K 90 used in cosmetics?
Yes. Its main uses are hair gels, mousses, pump sprays and liquid styling preparations; it gives strong hold and high viscosity. Vinylpyrrolidone polymers have been found safe by the CIR for cosmetic use.

Is Polyvinylpyrrolidone K 90 used in food or pharmaceuticals, and does it have an E code?
Yes, to a limited extent. It is registered in the EU as a food additive under the code E 1201, and the permitted use is limited to food supplement and sweetener tablets. In pharmaceuticals, grades such as Kollidon 90 Evo are offered as binders and excipients.

What is the difference between Polyvinylpyrrolidone K 90 and Polyvinylpyrrolidone K 30?
The difference lies in chain length. The molecular weight of K 90 is more than ten times higher than that of K 30; its solution is much more viscous, and its binding power and adhesion are stronger. K 30 gives a more fluid solution, dissolves faster and is easier to process in operations such as granulation liquid.

What is Polyvinylpyrrolidone K 90 used for?
It is used for strong binding, giving consistency, tack, film forming, retarding crystallization and stabilizing suspensions. Tablets, hair products, glue sticks, crop protection suspensions, membranes and nanomaterial synthesis are the main examples.

In which sectors is Polyvinylpyrrolidone K 90 used?
It is used in pharmaceuticals, cosmetics and personal care, adhesives, agriculture and crop protection, membranes and filtration, nanomaterial synthesis, electrospinning, laboratories and assisted reproduction.

How does Polyvinylpyrrolidone K 90 perform its binding function?
It dissolves in the granulation liquid, wets the powder particles and, during drying, forms film bridges made of long chains between the particles. The hydrogen bonds of the carbonyl groups provide adhesion to fillers such as lactose and cellulose.

What does Polyvinylpyrrolidone K 90 do?
It gives hardness to tablets, hold and consistency to hair products, initial tack to adhesives, stability to suspensions and wettability to membranes; it helps retard crystallization in poorly soluble active ingredients.

How does Polyvinylpyrrolidone K 90 work in hair styling products?
As the solvent evaporates it forms a film on the hair strands and the chains thicken the solution; the strands stick to one another and take shape. Because it is hygroscopic, hold may decrease in humid air; in that case use together with vinyl acetate copolymers or carbomer is evaluated.

Is Polyvinylpyrrolidone K 90 soluble in water?
Yes, very well; BASF reports a solubility above 10 g/L in water. It also dissolves in ethanol, isopropanol, methanol, glycerol and chloroform; it does not dissolve in ether, toluene and hydrocarbons. The powder should be added slowly under stirring and time should be allowed for dissolution.

How much Polyvinylpyrrolidone K 90 is used as a tablet binder?
BASF gives the typical binder level as 1–5 percent; examples include 1.5 percent in microcrystalline cellulose, 2.5 percent in dicalcium phosphate and 2.5 percent in a fluid bed. The actual amount is determined by trials according to the active ingredient, the method and the target hardness.

Is Polyvinylpyrrolidone K 90 a hazardous substance?
In most SDSs it is not classified as a hazardous substance. Its acute oral toxicity is very low. Fine dust can form combustible dust and can irritate the eyes; work should be carried out with suitable protective equipment and without raising dust.

Why does Polyvinylpyrrolidone K 90 take up moisture and can it form peroxides?
Because the carbonyl groups bind water by hydrogen bonds, it is hygroscopic. The carbons next to the nitrogen, on the other hand, tend to react with oxygen; hydroperoxides may form during storage. For this reason moisture- and oxygen-barrier packaging is important.

Is Polyvinylpyrrolidone K 90 registered under REACH?
Polymers are excluded from the registration obligation under REACH; the monomer N-vinylpyrrolidone, on the other hand, is registered. The current regulatory status of the product and supplier notifications should be confirmed with the supplier.

What is the physical appearance of Polyvinylpyrrolidone K 90?
It is a white to slightly yellowish, odorless or very faintly odorous, hygroscopic powder. Its particles are coarser than those of K 30 and its flow is weaker; some grades are sold as an aqueous solution of about 20 percent.

What is the UN number of Polyvinylpyrrolidone K 90?
The safety data sheets examined state that the solid product is not regulated as a dangerous good; for this reason there is no UN number or hazard class. For solutions or complex products the situation should be checked from the supplier’s SDS.

Why are residual monomer and peroxide important in Polyvinylpyrrolidone K 90?
Residual N-vinylpyrrolidone is a monomer with a carcinogen classification; its limit in pharmaceutical grade is 10 ppm. Peroxides, on the other hand, can degrade active ingredients sensitive to oxidation; for this reason the limits should be verified from the certificate of analysis.

What does the price of Polyvinylpyrrolidone K 90 depend on?
The price varies with the grade (pharmaceutical, food, cosmetic or technical), K-value range, form, packaging, order quantity, origin, certification, monomer and peroxide limits, raw material costs and logistics conditions.

Is there an alternative to Polyvinylpyrrolidone K 90?
Yes. K 30, K 120, copovidone, polyvinyl alcohol, hydroxypropyl cellulose, hypromellose, carbomer and vinylpyrrolidone copolymers can be alternatives depending on the application. None is a direct substitute in every system.

How should Polyvinylpyrrolidone K 90 be stored?
It should be stored in a cool, dry, well-ventilated place, in its closed original packaging, away from moisture, heat and oxidizing substances. An opened package should be closed immediately and dust accumulation should be prevented.

Which documents should be requested when buying Polyvinylpyrrolidone K 90?
SDS, TDS and batch-based COA are the basic documents. In addition, pharmacopoeial compliance, REACH information and a supplier declaration for pharmaceutical, food or cosmetic use may be requested.

Which technical specifications are important when buying Polyvinylpyrrolidone K 90?
The K-value range, molecular weight and measurement method, nitrogen content, moisture, residual monomer, peroxide, pH, solution viscosity, particle size, grade type, shelf life and packaging are important.

POLYVINYLPYRROLIDONE K 90 – TECHNICAL SUMMARY

Chemical name: Poly(1-vinylpyrrolidin-2-one); 1-ethenylpyrrolidin-2-one homopolymer, K-value about 90

Common name: Polyvinylpyrrolidone K 90, Polyvinyl pyrrolidone K 90, Povidone K 90, PVP K 90, Kollidon 90 Evo, Plasdone K-90, Luviskol K 90

CAS No: 9003-39-8

EC / EINECS No: There is no single number for the polymer; some documents show 201-800-4, the number of the monomer

Molecular formula: (C₆H₉NO)ₙ

Molecular weight: 111.14 g/mol for the repeat unit; for K 90 the weight-average molecular weight in manufacturer documents is about 900,000–1,700,000; 360,000 on some catalogue labels

Chemical class: Synthetic, non-ionic, water-soluble N-vinyllactam polymer

Physical appearance: White to slightly yellowish, odorless or very faintly odorous, hygroscopic powder; some grades are an aqueous solution of about 20 percent

Key properties: Soluble in water, ethanol, methanol, glycerol and chloroform; insoluble in ether, toluene and hydrocarbons. Bulk density about 0.4–0.6 g/mL, specific gravity about 1.23–1.29, glass transition temperature about 156–176 °C depending on the manufacturer, viscosity of a 20 percent solution 10,000–30,000 mPa·s. Nitrogen content 11.5–12.8 percent; moisture at most 5 percent

Main functions: Strong binder, tackifier, thickener, film former, crystallization retarder, suspension stabilizer, colloid protector

Important fields of application: Tablet and solid dispersion formulations, hair styling, glue sticks, crop protection suspensions, membrane hydrophilization, electrospinning, silver nanowire synthesis, laboratory

Parameters critical for quality control: K-value range, molecular weight and measurement method, nitrogen, moisture, residual N-vinylpyrrolidone, peroxide, aldehyde, heavy metals, pH, solution viscosity, particle size and documents suited to the grade

Storage: In a cool, dry, ventilated area, in closed moisture- and oxygen-barrier original packaging; kept apart from moisture, heat and oxidizing substances; shelf life 36 months for Kollidon 90 Evo and Luviskol K 90

Regulation: Not classified as a hazardous substance in most SDSs; fine dust may form combustible dust. Permitted in the EU for limited food use as E 1201, its INCI name is PVP, and it has a pharmacopoeial monograph in pharmaceuticals; cross-linked PVPP (E 1202) is a separate substance. Conditions of use and transport should be confirmed with the supplier and current legislation.