Polyvinylpyrrolidone PVP- POvidone K30-90

polyvinyl pyrrolidone (PVP), referred to as PVP, is a non-ionic polymer, povidone K30-90 and other models, is the most characteristic of N-vinyl amide polymers,

and has been the most studied and widely used fine chemical variety. Has developed into non-ionic, cationic, anion 3 categories, industrial grade, pharmaceutical

grade, food grade 3 specifications, relative molecular mass from thousands to more than one million homopolymer, copolymer and crosslinked polymer series

products, and with its excellent unique properties have been widely used.

Average molecular weight: 8000-700000

Stability: stable under normal temperature and pressure

Solubility: easily soluble in water and halogenated hydrocarbon solvents, alcohols, amines, nitroalkanes and low molecular fatty acids, insoluble in acetone, ether, turpentine, aliphatic hydrocarbons and alicyclic hydrocarbons and other solvents. It is compatible with most inorganic salts and various resins.

Properties: Hydrophilic and easy to flow white or nearly white powder, with a slight odor.

A crosslinked homopolymer of pure vinylpyrrolidone. Polyvinylpyrrolidone (PVP) has the ability to bind to a variety of substances, such as the various pigments that cause wine and other beverages to discolor. And because of its insolubility, it is easy to be removed after filtration.

PVP application

The application of PVP in binder

PVP has special adhesion to glass, metal and plastic, paper, fabric surface; Coupled with its characteristics of hydrophilicity, dispersion stability, non-thixotropy, thickening, etc., it is widely used in various binder formulations. There are two types of applications. The first class is to use PVP as the main component of the adhesive, and the other class is to use the adhesive properties of PVP in other products that need binder components, such as coatings, inks, glazing agents, various tablets, granules, sintered materials glaze and so on.

Application in adhesives

As the main component of adhesives, PVP is the most widely used in industry, such as solid glue sticks, pressure sensitive adhesives and rewet adhesives.

Solid glue stick is a new type of office (including school students) glue, because of its easy to use coating, strong initial adhesion, suitable for all kinds of paper, flat and wrinkly after bonding, to overcome the shortcomings of liquid glue, so nearly 30 years to become the world’s popular office supplies. As a solid glue stick binder should have strong bonding ability, especially good initial adhesion; Good coating, thin and uniform coating; Solid shape, no deformation when the coating is stressed, and can adapt to various climatic conditions; Long storage period, non-toxic. It has been proved that PVP is one of the few varieties that can meet all the above requirements among various water-soluble polymers. There are also solid glues on the market with PVA as the main bonding component, but they are generally difficult to overcome the gelling tendency of PVA, short shelf life, and eventually lose the bonding force.

The application test proves that the solid glue is suitable for all kinds of writing paper, waxing paper, copy paper, adhesive paper, letterpress printing paper, wrinkle paper, photographic paper, especially for small paper products can operate freely, that is, paste and write; It can also paste fabrics and polystyrene materials such as decorative foam paper. As a result, it has spread rapidly around the world. In the past ten years, China and South Korea have become the main production and export bases of global solid glue. The main raw material PVP K90 purchased by the two countries for the production of solid glue reached about 2,000 tons.

Another adhesive with NVP polymer as the main bonding component is a pressure sensitive adhesive. Adding PVP to the pressure-sensitive adhesive formula can improve the initial adhesion, strength and hardness of the tape. The copolymer of acrylate and NVP can be used as a protective film of fine materials, with repeated adhesion and stripping properties. Water-soluble polymers including PVP are widely used as adhesive components for medical skin pressure sensitive adhesives. Especially in the skin drug delivery film, this is a new controlled release drug delivery method. The drug film itself contains the drug that can be absorbed through the skin, and the NVP polymer acts as a binder, becoming a gel-like drug matrix that promotes the diffusion of the drug. The glyceryl nitrate used to treat heart attacks can be used to make such a film. For example, the copolymer of NVP and acrylic ester can be used as a carrier of bactericide iodine, which is fixed on the skin through its pressure sensitive adhesion, and becomes a local anti-infection skin drug administration film. Another type of medical pressure sensitive adhesive is to fix the electrode of the medical device on the skin, it is often a pressure sensitive adhesive can be used repeatedly, and can adsorb the electrolyte solution of the hydrogel, PVP can increase the strength of the hydrogel, improve its stability in the electrolyte.

The third binder with NVP polymer as the main component is the rewet adhesive, the so-called rewet adhesive refers to the dry state does not have bonding, and can play a bonding role in the state of water absorption. PVP, especially PVP/VA, is the main component of this class of binders due to its adjustable hygroscopic properties.

Selecting the appropriate molecular weight of PVP/VA and the ratio of VP to VA in the molecule can improve the flow temperature of the adhesive, the caking resistance at 75% relative humidity and the sensitivity to water.

In other products processing, production as a binder application

Because PVP has excellent adhesion to glass, it is used as a glazing agent for glass fibers to make the surface of glass fibers smoother, reduce wear during stretching, and increase the holding force of fiber bundles. Phenolic resin, saturated polyester resin cellulose derivatives, vinyl acetate/methyl methacrylate resin can be combined with PVP to form glass fiber glazing agent. Some formulations have been applied in some large glass fiber factories in China.

According to the same reason, PVP can also be used for the preparation and processing of many inorganic fibers such as carbon fiber, Al2O3 fiber, magnesium titanate fiber, and increase the bonding force of fiber and resin composite.

When glass, ceramics, quartz, asbestos, mica and other inorganic materials are used to prepare highly flexible and special paper, PVP can often disperse and bond the fibers and improve the strength of the paper.

PVP in fine ceramic processing, high dimensional precision sintered ceramics, controlled magnetic sintered ceramics, flexible ceramics, ceramic surface coating, ceramic, glass printing ink, porcelain glaze, nickel plated steel enamel glaze can be used as slurry, pigment dispersant, binder and has been widely paid attention to and applied. In ceramic processing, PVP can be completely burned during sintering. Therefore, there is no effect on the ceramic itself. PVPK90 also prevents the cracking of ceramic products before sintering. In glazes and inks, PVP’s affinity for pigments and dyes ensures uniform, stable and high adhesion of glazes and inks.

PVP is a forming binder for all types of industrial or domestic tablets and granules, such as cleaning tablets for dentures, painting paint tablets for children, sheet and block cleaning agents for household or industrial use.

PVPK30 and PVPK90 are good binders for the manufacture of gypsum bandages. PVP is dissolved in organic solvent such as methanol to generate methanol-pvp solution, the gypsum is dispersed in it, and then the suspension is applied to the bandage. After drying, the gypsum bandages with good plasticity and uniformity can be obtained, which reduces pulverized powder and increases elasticity and fastness.

PVPKl7 can be used as a binder for photographic paper.

All kinds of binder products have their special requirements and conditions of use, as long as the full understanding of the various properties of PVP and their relationships, you can play the bonding role of PVP in the development of many new products.

The global PVP used to produce binders is about 3,300 tons, accounting for more than 7% of the total consumption of PVP. As for the use in the production of various other products, the demand for PVP, which mainly plays a bonding role, is not included in the above data, and it is difficult to correctly count.

The application of PVP in medicine

Using PVP’s good solubility, solubilization, physiological compatibility, bonding ability and complexation ability, it can be used as binder, excipient, coating agent, release agent, co-solvent, germicidal disinfectant, solubilizer, sustained-release agent, capsule shell, dispersion stabilizer, film forming agent and so on in the field of medicine and health. In some developed countries, such as the United States, Germany, Japan, etc., the application of PVP in the field of medicine and health accounts for about 40% to 55% of the total consumption of PVP. Currently, PVP is in medical medicine

The application of PVP in medicine

Dosage form      Including PVP components      PVP content (% mass)      Main role

tabella               PVP-K30                                0.5 ~ 5                           Bonding, solubilizing, forming

particle              PVP-K30                                0.5 ~ 5                           Bonding, solubilizing, forming

Coating agent    PVP-K30                                0.5 ~ 2                            tablet (pill) coat, film forming agent

capsule             PVP-K30                                1 ~ 2                               Granulation aid, protectant, release agent

coprecipitant     PVP-K15, K17                          –                                     Increase dissolution rate

injection           PVP-K15, K17                         5 ~ 15                              Help dissolve, disperse

Oral liquid        PVP-K15, K60                         –                                       Disperse and thicken

Take a pill        PVP-K30, K90                         2 ~ 10                               Increase potency and reduce irritation

Germicidal       PVP-I                                     –                                        Sterilization, disinfection, reduce toxicity, irritation

lozenge           PVP-K30, K60                        0.5 ~ 5                               Give shape, slow release

The application of PVP in medicine and health

PVP has good bonding properties and strong dissolution ability. The tablets formed by PVP, after being taken in the digestive tract, dissolve quickly at first, so that the tablets locally expand and disintegrate, release drug fragments, and then accelerate the dissolution and absorption of the drugs, and play a rapid role in the efficacy of the drug. PVP is soluble in water and most organic solvents. For these reasons, PVP has been widely used in pharmaceutical tablets, especially in foreign countries. Examples of common drugs that use PVP for tablet bonding are as follows:

Compound sulfamethoxazole, aspirin, compound aspirin, paracetamol, vitamin C, dipyridamine, dimethyltetracycline, clonidine, benzene sulfonamide, compound analgesic, chewable tablets are illustrated as examples, and their formulations are as follows:

Aluminum hydroxide dry glue 0.4g

Magnesium hydroxide fine powder 0.08g

Powdered sugar 0.02g

Mannitol fine powder 0.2g

10%PVP ethanol (50%) solution 0.03g

Magnesium stearate 0.015g

Peppermint oil 0.0005g

As a drug tablet adhesive PVP is mainly PVP-K30, its dosage depends on the requirements of the mechanical strength of the drug tablet and the nature of the drug itself, generally 0.5% ~ 5%.

Another important use of PVP as drug excipients is co-precipitation agent, some drugs have good efficacy, but its fatal disadvantage is that the solubility in water is very small, resulting in its bioavailability is greatly reduced, the use of some water-soluble substances with these drugs co-precipitation, and then improve the solubility and dissolution rate of drugs, to reduce the dose, improve the efficacy of the effect. As a co-precipitant of insoluble drugs, PVP is being widely used.

The main reason why PVP is used as a drug coprecipitator is that carbonyl O in PVP molecules can be combined with active hydrogen bonds in insoluble drug molecules, which on the one hand makes relatively small drug molecules enter into PVP macromolecules in an amorphous state; on the other hand, hydrogen bonds do not change the water-soluble nature of PVP. As a result, insoluble drug molecules are dispersed in PVP macromolecules through hydrogen bonds, making them easily soluble. The solubility changes of some insoluble drugs after forming coprecipitates with PVP are as follows:

The solubility ratio of drug name to PVP coprecipitate was increased by multiple

Phenytoin 1:52.3

Morpholine 1:538

Reserpine (297-420um) 1:3 15

The increase of solubility of insoluble drugs in human body also correspondingly improves the bioavailability of drugs. For example, the bioavailability of drugs increased by 1.55 times after phenytoin co-precipitation with PVP, and the increase of solubility after co-precipitation of insoluble drugs was related to the molecular weight of PVP and the amount of PVP. In the case of the same amount (quality) of PVP, the increase of drug solubility decreases in the order of PVP-K15>PVPK30>PVPK90, because the solubification of PVP itself changes in the order of PVP-K15>PVPK30>PVPK90. In general, PVP-K15 is used more.

The solubility of insoluble drugs and PVP coprecipitates increases in a complex manner with the amount of PVP. For PVP with a certain molecular weight, each PVP molecule can bind to a certain number of drug molecules, and insoluble drugs often have a certain crystal state. When the amount of PVP is not enough to bind a certain amount of drug and make it in the amorphous dispersion state, the drug is still mainly in the crystalline state, and the solubility changes little. When PVP must reach a certain content, the drug appears as an amorphous dispersion system, and its solubility can be significantly increased to achieve the purpose of rapid dissolution and absorption. For different drugs, the content of amorphous dispersed PVP is different when it reaches the coprecipitate with PVP, such as 70% of cyclohexamine acetate. Drugs that can increase their solubility and bioavailability in humans by PVP co-precipitation include B-carotene, chloramphenicol, dexamethasone, hydroprednisone, streptomycin, tetracycline, and testosterone.

Similarly, the use of hydrogen bond association between PVP molecules and drug molecules can play the opposite effect of solution-increasing and quick-acting, slow release effect, control the degree of association between PVP molecules and drug molecules, and enable drug molecules to be slowly released in the human body after association, delay the dissolution rate, and prolong the effect of drug efficacy. PVP has prolongation effect on penicillin, chloramphenicol, insulin, sodium salicylate, procaine, cortione and other drugs.

In solid drugs, PVP can be used as a binder, solubilizer, disintegrator and delay agent, as well as a drug film coating, drug capsule shell and controlled release film. The drug film coat and capsule shell made of PVP are not easy to break in a dry environment, and the appropriate amount of PVP and other insoluble polymers together make permeable films of different thickness and different pore sizes, which can adjust the rate of drug passing through the film, and then achieve the effect of controlled release.

The application of PVP in liquid drugs

In addition to the many applications of PVP in solid drugs, PVP also plays an important role in injection and ophthalmic medicine. For example, PVP is used in some injections, because of the association between it and drugs, so that one side plays a role in solubility, on the other hand, for some agents that will crystallize or precipitate after too long, PVP can play a role in dispersion and stability. PVP used in ophthalmology can reduce the irritation to the eyes and prolong the action time of ophthalmology.

The application of PVP in medical hygiene, food and beverage hygiene, aquaculture sterilization and disinfection.

1. Application of PVP-I in medical and health care:

The application of PVP in sterilization and disinfectant is one of the most successful examples. PVP unique excellent small molecule complexation ability can be generated between the complex povidone iodine (PVP-I), has been collected by the United States Pharmacopoeia, British Pharmacopoeia, Japanese pharmacopoeia, Chinese pharmacopoeia, Martin Pharmacopoeia, and approved in the medical health, human body direct use of disinfection and fungicide. Povidone-iodine suppository, solution, ointment and other dosage forms are collected in Chinese pharmacopoeia. Povidone iodine has become an internationally recognized high efficiency, broad spectrum, non-toxic fungicide, it has a strong bactericidal power and a wide range of bactericidal spectrum.

Mechanism of action: PVP is a hydrophilic polymer, itself has no antibacterial effect, but because of its affinity to the cell membrane, it can directly lead iodine to the bacterial cell surface, which is of great significance to improve the antibacterial activity of iodine. Iodine targets the bacterial cytoplasm and cytoplasmic membrane, killing bacteria instantly within seconds. When the molecules necessary for the survival of organisms such as hydrophobic compounds, peptides, proteins, lipids and cytosine come into contact with PVP-I, they are immediately iodized or iodized to lose their activity and achieve a longer bactericidal effect. PVP-I can kill bacteria, fungi, viruses and protozoa. In vitro experiments on clinically common bacteria, almost no bacteria can not be killed.

Antibacterial spectrum: POvidone iodine can kill a variety of gram-positive and negative bacteria, spores, fungi, Escherichia coli, dysentery bacillus, tetracococcus, Bacillus subtilis, Proteus, Pseudomonas aeruginosa, gonococcus, Pseudomonas maltophilus, citrobacter, Bacillus diphtheriae, Bacillus papiformis, Bacillus anthracis, Candida albicans, flagellates, chlamydia.

Application: It is mainly used for gynecological inflammation, skin inflammation of acne, oral inflammation, oral ulcer, burn, scald, various trauma, surgical operation, skin disinfection before injection and disinfection of medical instruments.

2. Application of PVP-I in food and catering hygiene
PVPI’s excellent sterilization ability and physiological compatibility show that it has no irritant and allergic reaction to the human body, so that it also has a wide range of uses in food preservation, disinfection of the catering industry, etc., in some aspects, it shows unique advantages, such as once a week with 0.1%PVP-I solution spray refrigerator, can ensure that there is no odor in the refrigerator for a long time.
3. Application of PVP-I in aquaculture industry

The application of PVP-I in aquaculture industry is developed in recent years, and the scope of use is being further expanded. With the further development of aquaculture industry in China, PVP-I as a disinfectant in aquaculture industry has broad prospects. PVP-I is a broad-spectrum disinfectant, which can kill most bacteria, fungi and viruses to varying degrees, and is used for the prevention and treatment of diseases of fish, shellfish, shrimp and crabs. In livestock breeding disinfection and disease treatment also have obvious effects.
The application of PVP in cosmetics and care products

Due to its excellent surface activity, film forming properties, no irritation to skin and no allergic reaction, PVP has broad prospects for application in the daily chemical industry, especially in cosmetics, skin care products, hair care products and washing products.

The application of PVP in cosmetics:

The research on the application of PVP in cosmetics began in the 1960s, and now it has been widely used in hair care products, skin care products, ornaments and other aspects, among which the most prominent is the application in hair care products. As an excellent surfactant, adding PVP to shampoo can make the foam stable. Because of its physiological compatibility, it will not cause irritation and allergic reactions to the skin, long-term use will not damage the hair, and the hair after washing is smooth and shiny and easy to comb. Hair spray and mousse with PVP have long-lasting styling, good luster, and because PVP has certain water absorption, it makes hair smooth and smooth without appearing dry. PVP for hair care products can be used through the selection and proportion of copolymer monomer types. PVP, which regulates its water absorption and is suitable for dry, neutral and oily hair as a hair conditioner, has unique advantages. The main component of hair is protein, and the molecular structure of PVP is also similar to protein, so it can be used as a supplement for hair nutrients. Long-term use of shampoo and hair care products containing PVP can make hair black and shiny. Reduce split ends.
The role of PVP in other cosmetics is mainly to stabilize the dispersion system such as emulsion and suspension, moisturizing and film-forming role in skin care products, such as PVP in sunscreen, not only moistens, but more importantly, isolates the skin from the sun by forming a film, which plays a role in protecting the skin. In addition, PVP has special uses in other aspects, such as pigment stabilizer, deodorant, deodorant, toothpaste, shaving cream and many other cosmetics.

The application of PVP in washing products

 

The excellent surface activity of PVP makes it also have a good effect as an ingredient in some washing products. PVPP’s cross-linked polymer PVPP is used as an ingredient in toothpaste, which can not only remove dirt and antifouling, but also have anti-inflammatory and analgesic effects.
PVP acrylic copolymer used in bath not only has the role of dispersion stabilizer, detergent, and sterilization and disinfection function, especially as a medicated soap, soap ingredients used in the summer has a good effect, PVP both oil and water wet properties make it in the cleaning of clothing, especially in the cleaning of hotels, restaurants with tablecloth cleaning agent has a special effect. For example, Guangzhou Jinyuan Detergent products factory with BASF production of “table cloth net” for washing tablecloth, not only washing time is short, washed tablecloth white and soft, there is a light fragrance smell, and both sterilization and disinfection effect.

 

In summary, the function of PVP in daily chemical products is mainly manifested in the following aspects:

 

Dispersion stability function, common skin care products, creams and other cosmetics are mostly lotions and suspensions, to make it can be placed for a long time without precipitation deterioration, so that it is dispersed into a uniform system and has a certain stability time is very important, PVP in cosmetics an important function is dispersion stability function.

Decontamination washing function, PVP and its copolymer due to its specific molecular structure, on the one hand has a lipophilic, can remove clothing, hair and skin oil, sweat stains, etc., on the other hand has a good hydrophilicity, so it is easy to wash clothes and skin stains.

Film forming, moisturizing function, which is the most common function of PVP in cosmetics, widely used in hair care products, skin care products and so on.

Sterilization, disinfection function, mainly used in washing products.

The application of pvp in ink and ink

 

Writing pen ink and jet printing ink must have good stability and adhesion, so as to ensure that the writing is firm and does not fade, the ink does not precipitate and block the pen, and the printer does not block the nozzle when it runs jet printing for a long time. In addition, it is also required that when spraying or printing is stopped, there is no phenomenon of blocking the nozzle due to the drying and hardening of the ink remaining in the nozzle, which does not hinder repeated spraying, does not affect the direction of injection, and can maintain a smooth re-spraying state. In order to meet these requirements, polyols such as ethylene glycol, diethylene glycol, and glycerol have been used in the past as the wetting agent components of ink and ink, which can control the drying and curing in the nozzle when the injection is stopped to a certain extent. However, if it runs for a long time or stops for a long time (about a week), there is still residue deposition at the nozzle exit, which changes the spray direction or makes the writing line thickness uneven, or even completely blocks the nozzle, so that it can not get satisfactory results.

 

PVP has good adhesion properties, can be used as a binder, used in ink, ink can make writing and printing handwriting firmly attached to the paper and not easy to fall off and fade. Moreover, PVP has a good dispersion and stability effect on inorganic pigments and organic pigments dispersions, which can be used for ink and ink to obtain a uniform dispersion system, which is not easy to precipitate, does not block pens and various nozzles, and the depth of writing is uniform. And PVP is non-volatile, its role and function lasting. In particular, the printing or printing equipment will not block the nozzle if it stops running for a long time, and it has smooth and repeated spray writing performance. PVP for inks and inks are generally PVP-K12 to PVP-30 products with lower molecular weight.

 

As a printed matter, such as stamps, printer ribbon used in printing ink, due to the need for long-term use, so the need for light and water resistance excellent pigment as the ink coloring components, required as the main component of the pigment particles can be evenly dispersed, to avoid the dispersion of bad caused by agglutination, printing ink in the dispersion stability and viscosity and other aspects of performance if not good, It will make the painting and handwriting unsatisfactory. In addition, because the long-term use of printing equipment will lead to local temperature rise, the ink is also required to have a certain temperature stability.

 

Pv-k30 is added to the ink and ink to protect the colloid, thicken and increase viscosity, so that the writing is fluent, does not overflow, does not fade, can also reduce the wear of the ball and extend its service life.

Id cards and other kinds of documents such special objects are identified by the bar code above, in order to make the documents do not make mistakes, resulting in misunderstandings or serious errors, the production of bar codes must be sophisticated, accurate, and the use of time sometimes more than decades. In order to meet these requirements, the production of the document is achieved through a special magnetic ink, the main components of this ink are magnetic powder, adhesive and organic solvent, as a binder component added to the PVP can increase the adhesion stability of the bar code, and as a bar code substrate synthetic paper, artificial film to form a uniform bar code film. Make the bar code edge neat and firm, not easy to damage. The combination of PVP and polyethylene glycol has better effect.
The modulation method is to mix each component and process it in the ball mill for 24h, so that it is dispersed evenly, and the magnetic ink with an average particle size below 10μm is obtained after centrifugal separation to remove the coarse particles. A magnetic ink film with a thickness of 15μm was obtained by applying 25g/m2 coating on the surface of fine paper, synthetic paper (polystyrene), synthetic film (polyvinyl chloride), etc. The adhesive stability on the three substrates was very good. The adhesion stability is determined by the following methods: In the marketed viscosity of various magnetic ink samples, the adhesive is removed with a stripping speed of 1cm /s and a stripping Angle of 180°, so that the more adhesive is transferred to the adhesive, indicating that the adhesion stability of the magnetic ink skin film is poor; On the contrary, it indicates that the magnetic ink skin film has good adhesion stability to the corresponding substrate surface.

 

As the two main components of magnetic ink, magnetic powder and polyethylene are responsible for magnetic recording properties and adhesive functions respectively. In the above formulation, the ratio between γ-Fe2O3 and polyethylene (polyethylene glycol, polyethylene isoamyl alcohol ether, polyethylene pyrrolidone) can be adjusted to obtain magnetic inks suitable for different uses. For example, to increase the adhesion stability of magnetic inks on the substrate, it is necessary to increase the proportion of PVP-K30 or polyethylene glycol, by increasing the proportion of polyethylene glycol in magnetic inks used in general, and by increasing the proportion of PVP in more advanced magnetic inks. Adhesion stability can also be achieved by pressurizing the magnetic ink skin film on the substrate during the production process. The proportion of PVP in magnetic ink is generally between 1% and 5% according to the requirements of use.

The application of PVP in pigments and coatings

one. Application of PVP in the preparation of organic pigments

 

The surface treatment of pigments is a method of pigmentation, and the organic pigment particles obtained by chemical synthesis have a large surface energy, with a surface ratio of 8 ~ 100m2 /g. If the finished pigment is mechanically crushed, its particle size can only reach 70 ~ 100 μ. It can not be used directly. Therefore, people are interested in particle surface treatment technology with good dispersion performance. Because the surface treatment can change some properties of the pigment. Such as: thermal stability, resistance to strong dissolution, dispersion, color retention, chemical inertness and optical solid properties.

 

Because PVP has good film forming properties, soluble in water, insoluble in some organic media, and transparent film forming, does not affect the color, and can improve the luster and dispersion of the pigment, it is often used as a surface coating agent of organic azo pigments. The molecular weight Mw of the PVP polymer used for cladding must be greater than 300,000, its thickness is generally 0.001 ~ 1.6μ, the pigment particle size is about 0.1 ~ 10μ, 5 ~ 100 polymers per 100 pigments are required, and the polymer accounts for 20 ~ 50% of the pigment core weight in general. NVP can also be used to copolymerize with a small amount of ethylene unsaturated compounds, especially acrylates, such as acrylic stearate, acrylic hydroxyl substituting alkyl ester and other copolymers as coating agents.

 

The coated organic pigment has the following advantages:

a) Because the coating is insoluble in organic media, there will be no color diffusion during use.

b) After coating the surface of the pigment with a layer of molecular polymer, the contact between the azo group of the organic pigment and the external medium is cut off, thus preventing the photochemical reduction reaction between the azo group and the external medium triggered by ultraviolet light, which greatly improves the light fastness.

c) Increase the gloss of the paint film to avoid rough cracks.

d) Easy to crush, improve the coloring ability.
Organic pigments covered by PVP can be used in: (1) protective and decorative coatings, such as: lacquer, varnish, paint, etc. (2) aqueous dispersion system. (3) emulsions. (4) printing ink, fabric coloring and plastic coloring.

 

When the color material is added to the base material of the paint and pigment, because the base material will consume a part of the dispersant and surfactant, this effect is until the equilibrium is established. When there are enough dispersants and surfactants in the paint and pigment, the color is stable and uniform coating can be obtained. When the amount of dispersant and surfactant is not enough, the pigment system composed of color material and TiO2 filler will either flocculate or coalescence, which will reduce the coloring force, cause the viscosity to rise, and the pigment will caking. The usual solution is to add nonionic surfactants, but this creates a more serious foam problem. Therefore, how to improve the dispersion stability of coatings and pigments without reducing their coloring power is one of the important criteria for evaluating dispersants, and it is also a problem that the domestic coatings and pigments industry has been trying to solve.

2. The application of PVP in waterborne coatings

 

In water-based coatings such as emulsion coatings and water-soluble resin coatings containing pigments, the coloring effect is reduced due to the poor dispersion of pigments and the condensation and precipitation during storage, and the undesirable phenomena such as floating color and poor luster appear. For this purpose, a suitable dispersant is needed, however, the general low molecular weight surfactants have poor film formation, unstable rheological properties, and great limitations on the binder used. The polymer dispersant has the advantages of high stability, good rheology, good adsorption on pigment surface, improving coloring power and improving luster, etc., which is the development direction of pigment dispersant.

 

The Japanese patent believes that the use of (1) synthetic or natural saturated fatty acid modified acrylate, (2)NVP, (3)α, β-vinyl unsaturated acid, etc., according to a certain proportion of the synthetic dispersant, can make the pigment good dispersion, but also has good film formation, can improve the performance of water-based coatings, suitable for many organic, inorganic pigments and water-based resins.

 

In the emulsion coatings with styrene and methacrylate as the main body, due to the low viscosity of emulsion, water-soluble polymer addition method, solvent addition method, alkaline thickening method, evaporation and concentration method were used to thicken. The main disadvantage is that the viscosity of the latex is difficult to control, changes with time, and the water resistance of the coating is reduced. If polyvinyl alcohol is used as a thickener, it has a strong tendency to coagulate or gelate, and can not obtain stable high-viscosity latex. In the presence of PVP, the low viscosity synthetic resin emulsion with a viscosity below 1000cp can be changed into a stable high viscosity synthetic resin emulsion with a viscosity above 10000cp by evaporation and concentration. The coating prepared by the emulsion with this method has the advantages of no hanging, good water resistance, hard skin film, no discoloration, no shedding and dirt resistance.

 

When the content of the substrate pigment is high, the thixotropy is obvious, the fluidity is poor, and the film is easy to protruding. However, if PVP and other leveling agents are added to the styrene acrylic emulsion, a coating with high pigment content (non-volatile content of more than 70%), high viscosity, good leveling and smooth film can be obtained, and a smooth coating can be obtained by pressing, and the paint amount is less, the luster is good, and the pollution resistance.

 

In recent years, the use of microencapsulation technology can further improve the dispersion stability of pigments, improve the covering ability and anti-fouling properties of coatings. United Carbon’s patent proposed the polymerization of vinylpyrrolidone in a suspension system composed of pigment and water, the solid phase particles were dispersed at the same time, and then the introduction of vinyl acetate monomer and butyl acrylate continued to polymerize on the surface of the solid particles to form a film, and finally got a stable coating dispersion, with the coating obtained by the coating can prevent the contamination of food.

 

3. The application of PVP in special coatings

 

The surface of the printing paper is generally coated with an overlay. A transparent coating containing PVP allows the printing ink to dry quickly on it. The transparent layer has good ink absorbency, insoluble in water, and has good coagulability and diffusivity. And high-speed imaging due to transparency. Especially suitable for multi-color ink printing.

 

PVP can also be used in the preparation of conductive coatings. A conductive plastic film made to prevent electrostatic hazards is made by thinly coating the plastic film with a conductive transparent coating containing carbon black and a binder, and then coating it with a transparent protective layer. PVP is used here as a carbon black binder. In the past, water-soluble polyvinyl acetate alkalinates were used as binders, but satisfactory diluents could not be obtained, and there were problems such as drying difficulty and poor leveling. If PVP is used instead, a conductive coating with good conductivity and transparency, uniform coating and easy drying can be obtained. Generally, the molecular weight of PVP is 10000, because low molecular weight PVP is also beneficial to carbon black dispersion. In addition, if the coating content needs to be increased, it can be adjusted by adding polymer PVP.

Application of PVP in polymer industry

 

Polyvinylpyrrolidone is a kind of polymer surfactant because of its molecular structure with hydrophilic groups and oleophilic groups, as well as good adsorption ability to solid particles surface, so it can change the interface or solution state. In different dispersion systems, PVP with different molecular weight can be used as dispersant, stabilizer, emulsifier, thickener, leveling agent, particle size regulator, anti-reprecipitating agent, coagulant, co-solvent, and washing aid. In coatings, pigments, inks, polymer synthesis and processing, detergents, binders, photosensitive materials, drugs, cosmetics, food and other industrial processes or industrial products, PVP has been widely used for its excellent solubility, film formation, physiological inertia, complexing ability and other comprehensive characteristics.

 

The application of PVP in dispersion polymerization

 

PVP can be used as thickener, stabilizer and particle size regulator in polymer emulsion polymerization and suspension polymerization. Generally speaking, PVP with larger molecular weight (K>60) acts as a protective agent to prevent suspension precipitation, prevent the aggregation of larger particle size particles in the emulsion and dispersion solution, and make it stable. Low molecular PVP is more suitable for dispersing agents, especially for dispersing low density substances. Of course, the molecular weight and its distribution must be compatible with the particle size and distribution of the dispersion.

 

PVP and NVP copolymers can be used in styrene homopolymerization and copolymerization, suspension polymerization of vinyl chloride, methacrylate and polyurethane, emulsion polymerization of acrylic ester and vinyl carboxylate, which can play an excellent role in dispersion stability, particle size control, viscosity adjustment and resin performance improvement.

 

In the suspension polymerization of granular polyurethane urea, some of the previous technologies use organic solvents, and some can only get water dispersion or get large chunks after solidification, which brings inconvenience to the use and transportation, increases the processing cost, and affects the product quality. Therefore, it is urgent to develop a one-step synthesis technology of polyurethane urea with small particle size. In this one-step polymerization technique, the obtained solid phase polymer is not easily emulsified and can be separated by conventional separation methods. The particle size of polymer can be controlled by controlling the stirring speed and selecting dispersant. PVP is particularly suitable as a suspension stabilizer for this one-step polymerization. Its addition amount is about 2.5 ~ 5.0% of the water phase, and its molecular weight takes K value of 60. When the reaction is over, the toluene – water – is steamed

 

Azeotrope can be cooled, filtered, washed and dried to obtain powder urethane. When the amount of PVP K60 was 2.5%, the polymer particle size was 800 μ-1000 μ. The isocyanate content of the polymer is less than 0.5%, basically non-porous, and can be used in coatings, binkers, flocculants, laminate composites, to make films, with a thickness of 100 μ. As a coating, with a thickness of 10 μ.

 

It is well known that the type and concentration of suspension stabilizer has a decisive influence on the shape, size and morphology of the polymer. In some suspension polymerization, only the stability of PVP K90 and PVA can produce uniform particle size beads with porous shells. This proves that PVP has a good stabilizing effect.

 

When methyl methacrylate, vinyl acetate, polyethylene, chloroprene and other monomers are polymerized, the resulting products often have high elasticity only at the temperature of 120 ~ 150 ° C, and contain impurities such as unreacted initiators. However, when PVP K30 or PVP K15 was introduced as emulsifier, the high elastic temperature range of methyl methacrylate polymer was 120 ~ 280 ℃. When emulsion polymerization is performed at 50 ℃, the polymerization monomer can be completely transformed in 20 minutes to 100 minutes, and the resulting polymer flow temperature is 270 ~ 280 ℃.