PVA dispersion: properties, application and use. Aqueous polymer dispersions Plasticized PVA dispersion

| 25.11.2015

Homopolymer coarse PVADs

This type of dispersion with particle sizes up to 1-3 microns is produced by the domestic industry on a large scale. Coarsely dispersed PVADs have exceptionally high resistance to various factors: they can withstand repeated freezing and thawing, heating to almost 100°C, and the introduction of various fillers, including electrolytes. The disadvantage of these dispersions is the relatively low water resistance of the coatings they form, their low transparency, and lack of gloss. Homopolymer coarse PVADs are produced by emulsion polymerization of VA in the presence of a protective colloid - PVA and a redox initiating system H2O2 - FeSO4 at a pH of 2.8-3.2 using a periodic or continuous method. The choice of a specific formulation depends on the characteristics of the brand of the resulting dispersion (viscosity, solids content), as well as on the quality of the feedstock (MM PVA, sodium acetate content in it, monomer activity, etc.). Emulsion polymerization of VA is carried out by a periodic method in reactor 4 made of chromium-nickel steel with a capacity of 4-16 m3, equipped with an anchor or anchor-blade mixer, a jacket for heating and cooling, as well as a system of two series-connected refrigerators, one of which is cooled by circulating water, the other - water with a temperature not higher than 5°C or brine. From the apparatus for preparing the aqueous phase, a solution of PVA and formic acid is loaded into the polymerizer through a measuring cup. An aqueous solution of FeSO4 is introduced directly into the polymerizer. The heat of reaction is removed mainly due to the evaporation of the azeotropic mixture of VA and water, condensing in reflux condensers 5 and 6; 20% of the heat is removed through the jacket of the device. To facilitate the operating conditions of the heat removal system, VA and hydrogen peroxide are supplied in 3-5 doses. The polymerization temperature is initially determined by the boiling point of the azeotropic mixture VA - water (65-68 °C); as the reaction proceeds and the monomer content decreases, the temperature of the reaction mixture rises to 70-75 °C, and it should not exceed 92 °C. Upon completion of the polymerization of the last portion of VA, the reaction mass is cooled to a temperature of no more than 60 ° C and pressed under compressed nitrogen into standardizer 7 with a capacity of 6 - 40 m3. If the content of residual VA in the dispersion exceeds 0.5% (wt), the monomer is distilled from the polymerizer or standardizer at 75-85 °C and a residual pressure of 200-266 hPa. In the standardizer, the dispersion is neutralized with an aqueous solution of ammonia to pH 4.5-6 in order to prevent corrosion of equipment during its subsequent processing. To prevent dilution of a dispersion containing low values pH, it is advisable to neutralize PVAD with powdered calcium oxide or hydroxide. Due to the relatively high glass transition temperature of PVA (28 °C), brittle films are formed when HSAD dries, which does not allow the dispersion to be used for coatings, and in many cases, as an adhesive. To reduce the glass transition temperature of the polymer, the dispersion is plasticized with DBP. If PVAD is used for the manufacture of containers and other purposes in Food Industry, as a plasticizer. Torah use less toxic dibutyl sebacate. The operation of plasticizing the dispersion is carried out in a standardizer by uniformly introducing the plasticizer into the PVAD with stirring for 2.5-3.5 hours, the temperature of the dispersion should not exceed 50 °C. Mixing of the dispersion continues for another 5-12 hours until the polymer is finally combined with the plasticizer. The plasticization process is usually accompanied by an increase in the viscosity of PVAD, the greater the higher the plasticization temperature. The plasticized dispersion is not frost-resistant, therefore winter period PVAD and plasticizer are transported and stored separately, which increases transportation costs and requires the use of special equipment to plasticize the dispersion before use. The introduction of 0.2-0.5% (wt.) maleic anhydride into the dispersion, followed by heating the composition for 2 hours at 68-72 °C makes it possible to obtain frost-resistant plasticized PVAD. The dispersion's resistance to freezing is determined by the formation of an acidic ester of PVA and maleic acid, which improves the surface-active properties of the protective colloid. Heating the composition to a higher temperature is accompanied by an increase in the viscosity of PVAD, up to its transition to a paste-like state. Shipment finished products carried out in barrels, railway tanks or in other containers provided for by GOST 18992-80. The container is made of aluminum, stainless steel or lined with polyethylene. The containers are filled by pressing the PVAD with compressed nitrogen from standardizers or storage facilities through a mechanical screw classifier. The dispersion is pressed through the classifier mesh, and pieces and films of polymer are unloaded by a screw and sent for waste destruction. A method has been developed for optimizing the emulsion polymerization process of VA, based on the joint solution of model equations that determine the dependence of the quality indicators of PVAD on the formulation and polymerization mode. It allows you to choose optimal conditions to obtain any brand of PVAD, ‘providing high quality product: minimum content of insoluble part, residual VA, resistance to dilution, etc. Polymerization of VA by a continuous method is carried out in a unit consisting of stepped polymerization reactors with a capacity of 0.8-2.5 m3, interconnected by overflow pipes (crossflows ). The reaction mass flows along them from the upper part of the previous reactor into bottom part subsequent. The optimal number of polymerization reactors, determined by method mathematical modeling taking into account the features of emulsion polymerization of VA in the presence of PVA (complete segregation of particles) turned out to be equal to five. After polymerization is completed, the dispersion is cooled in coolers 10 and enters a standardizer, from which, under a vacuum created by a vacuum pump, unreacted monomer is removed. The remaining operations are practically no different from those described for the periodic method. Installation continuous action automated, its productivity is 700-4000 kg/h PVAD, depending on the capacity of the polymerizers.

Homopolymer ton-disperse PVADs

Finely dispersed homopolymer PVADs with a particle diameter of up to 0.5 μm are obtained by emulsion polymerization of VA in the presence of an emulsifier and initiator ammonium persulfate at pH 8-10, providing maximum speed initiator decomposition. This type of dispersion, unlike coarse PVADs, forms shiny, waterproof coatings when dried and is used primarily in the production of high-quality water-based paints. To obtain finely dispersed PVAD, the following installation can be used: a solution of ammonium persulfate and VA is introduced into the polymerizer in five equal portions, with each subsequent portion being fed after the completion of polymerization of the previous one, as in the periodic process of obtaining coarse PVAD. After polymerization is completed, the dispersion is cooled to 20-40 °C and, using compressed nitrogen, is pressed into a standardizer, where plasticization is performed. The finished PVAD is poured into containers for shipment to the consumer. The finely dispersed PVAD obtained in this way is not frost-resistant, so it can be transported and stored only at a temperature not lower than 5 °C. To impart frost resistance to the dispersion, 3 parts (wt.) of MBM are added to VA at the polymerization stage. After completion of polymerization, the dispersion is neutralized to pH 6.5-7.5 with diluted ammonia water with a concentration of no more than 12% (wt).

Vinyl acetate copolymer dispersions

The method of plasticizing dispersions with external plasticizers has a number of disadvantages, including the possibility of migration of the plasticizer from the polymer, its volatilization, and the increased toxicity of most plasticizers. All of these disadvantages are devoid of another method of plasticizing PVA - copolymerization of VA with monomers that impart increased elasticity to the copolymer. The most widely used comonomers for the preparation of copolymer dispersions based on VA are esters of maleic and acrylic acids and ethylene. Dispersions of copolymers of vinyl acetate with dibutyl maleate are produced in the form of both medium-dispersed products with a particle size of 0.8-1.5 microns, the synthesis of which uses high-molecular-weight surfactants (incompletely hydrolyzed PVA), hydroxyethylcellulose or mixtures of these polymers with low-molecular-weight surfactants, and finely dispersed ones based on an emulsifier S-10. A dispersion of copolymer VA with DBM, obtained in the presence of a mixture of hydroxyethylcellulose and the nonionic emulsifier proxanol-168, has increased frost resistance. Dispersions of vinyl acetate copolymers with acrylic acid esters are prepared using 2-ethylhexyl acrylate (2-EHA), butyl acrylate, and acrylic acid as comonomers. When copolymerizing VA with 2-EHA in an emulsion, PVA in combination with proxanol-168 is used as a protective colloid, and the H2O2-FeSO4 redox system is used as an initiator. The copolymerization process proceeds in the same way as in the production of homopolymer PVAD, in acidic environment at a pH of the aqueous phase of 2.8-3.2, achieved by the introduction of formic acid. Due to the higher activity of 2-EHA compared to VA, to obtain a compositionally homogeneous copolymer, a compensatory copolymerization method is used, first introducing all of VA and only 2.5% (wt.) of the calculated amount of 2-EHA, and then gradually throughout the entire copolymerization process load the remaining amount of 2-ethylhexyl acrylate. Dispersions of ternary copolymers of VA with butyl acrylate and acrylic acid are obtained by emulsion copolymerization of these monomers using C-10 as an emulsifier mixed with sulfanol. Dispersions of VA copolymers with acrylic and maleic acids, neutralized with ammonia, form highly viscous aqueous solutions. Dispersions of copolymers of vinyl acetate with ethylene (SVED) have the ability to form films even at low temperatures, and films based on them are water-, light- and weather-resistant, and are also relatively resistant to alkaline hydrolysis. In addition, the advantage of SVED is that it is more low cost not only in comparison with other copolymer, but also homopolymer dispersions due to the use of cheap ethylene as a comonomer. SVED is obtained by copolymerizing VA with ethylene in autoclave reactors at pressures up to 5 MPa by batch and continuous methods. To synthesize coarse grades of SVED, a protective colloid (PVA) and a redox initiating system H2O2-FeSO4 are used. Finely dispersed SVEDs are obtained in the presence of an emulsifier S-10 or OP-10 and an initiator - potassium or ammonium persulfate. The pressure at which the process is carried out is higher, the more ethylene units that must be introduced into the copolymer macromolecule. In addition to ethylene, vinyl chloride can be introduced into the copolymer, which helps to increase the strength, water and alkali resistance of films and coatings obtained from dispersions. The preparation of the aqueous phase is carried out in devices with a capacity of up to 60 m3, equipped with a jacket and a stirrer. When producing SVED, approximately the same ratio of components of the aqueous phase is used as in the production of PVAD. The copolymerization reaction takes place in a polymerizer-autoclave periodic action capacity 20 m3 with heat exchange mixing device tubular type and a multi-zone jacket that serves to remove the heat of polymerization (- 1880 kJ/kg of copolymer). The aqueous phase is pumped into the polymerizer by pump 2, after which the apparatus is filled with ethylene to a pressure of 2.6 MPa in the production of coarse SVED grades or 5 MPa in the case of synthesis of fine SVED grades. VA in apparatus 6 is saturated with ethylene, which compensates for the loss of ethylene included in the copolymer. In addition, due to the partial dissolution of ethylene in VA, the homogenization of comonomers improves and the ethylene content in the copolymer increases. The dosage of ethylene-saturated VA and the initiator into the polymerizer is carried out for approximately 10 hours at 60-70 °C. Isolation of polymers from dispersions As a rule, PVADs are used in various industries National economy in the form of water-dispersed products. But in cases where the cost of transporting water is too high or it is necessary to obtain dry compositions based on PVA, VA homo- and copolymers are isolated from dispersions in the form of powders. After mixing in water, these powders again form stable dispersions, which is why they are called redispersible. Redispersible PVA and VA copolymers are obtained by drying the corresponding dispersions with a concentration of 20-25% (wt.) in dryers from Anhydro or Niro Atomizer (Denmark). The dispersion is sprayed using a special nozzle or a rapidly rotating disk; hot nitrogen or air is supplied to the dryer from the side of the spray device. The gas temperature at the inlet to the dryer is 80-85 °C, at the outlet 35-40 °C. The dry powder is separated in a cyclone and the air is released into the atmosphere; when nitrogen is used, closed loop. The finished redispersible powder has a moisture content of no more than 2% (wt). The redispersing effect can only be obtained in the case of dehydration of coarse products obtained in the presence of protective colloids, usually PVA. To prevent the powder from sticking to the walls of the dryer and clumping, 0.5-10% of aerosil by weight of the polymer is added to the dispersion. Dispersions modified with thermosetting resins One of the main disadvantages of PVADs when used as coatings and adhesives is the low water resistance of the resulting materials, which is due to the presence of hydrophilic protective colloids or emulsifiers in the dispersions, as well as the high polarity of the molecules of the PVAD itself. There are many ways to modify PVLD in order to increase the water resistance of the films, coatings and adhesive joints. One of the most technologically advanced methods for modifying coarse homo- and copolymer dispersions is the preparation of PVAD compositions with thermosetting oligomers. The production of such compositions is possible at dispersion manufacturing plants. Epoxy resins of the ED-20 and UP-160 grades or resol phenol-formaldehyde resin in the form of an alcohol solution—bakelite varnish LBS-1—are used as thermosetting oligomers for modifying PVAD. Combination of PVAD with epoxy resin produced in devices equipped with a stirrer, at room temperature. The dispersion is loaded into the apparatus and, with constant stirring, equal amounts of epoxy resin (up to 30% by weight of PVA) and demineralized water are gradually added to it over 2-4 hours. Mixing after loading of resin and water is completed until the dispersion is completely combined with the resin, determined visually. Modification of PVAD with bakelite varnish is carried out under similar conditions. Bakelite varnish, previously diluted with ethyl acetate in an amount of 10% of the varnish weight, is added to PVAD gradually over 5-6 hours, after which the composition is mixed for another 2-3 hours. The ratio of PVAD and bakelite varnish is from 100:40 to 100:50 mass. The introduction of ethyl acetate into the composition prevents the precipitation of phenolic resin from the solution when mixing the varnish with aqueous dispersion. As a result of mixing PVAD with resins, water-dispersion compositions are obtained, which are multicomponent systems in which the combination of ingredients occurs during the process of film formation as water is removed. For complete curing of films (formation of polymers with a three-dimensional structure), the introduction of hardeners is required, which is usually polyethylene polyamine for epoxy resin, and acids, such as phosphoric or oxalic, for phenol-formaldehyde resins. When curing films obtained from a composition of PVAD with epoxy resin (PVAD), heat treatment at 110 °C for 3-4 hours is always necessary. Curing of films made from a composition of PVAD with phenol-formaldehyde resin (PVADF) can occur both in the cold (with the introduction of acid catalysts into the composition) and at 100-120°C without hardeners. PVAED and PVADF make it possible to obtain products with increased water resistance and mechanical strength in comparison with materials based on the original PVAD. However, a comparison of the properties of these two compositions shows that PVAED films are highly resistant to organic solvents, unlike films made from PVADF, but the latter have higher water resistance. This is explained by the fact that if, during curing of PVAED, structuring occurs throughout the entire volume polymer composition, then when PVADF is cured, the increase in water resistance is a consequence of the chemical interaction of the hydroxyl groups of the protective colloid (PVA) with the methylol groups of the phenol-formaldehyde resin. The water resistance of coatings and adhesive compounds made from coarse PVAD can also be increased by modifying the dispersions with urea resins, tetraethoxysilane and its hydrolysis products, isocyanates and other compounds that interact with the hydroxyl groups of PVA. The structuring of finely dispersed PVADs is carried out using “cross-linking” agents that react directly with the functional groups of VA srpolymers. For example, compositions from dispersions of copolymers containing units of acrylic or maleic acid and diglycidyl ethers of mono-, di- or triethylene glycol form coatings and films that acquire a three-dimensional structure when heated to 110-115 ° C. These structuring agents simultaneously act as dispersion plasticizers.

PRODUCTION OF POLYVINYL ACETATE BY SUSPENSION METHOD

To polymerize VA in suspension, you can use the same polymerizers as for producing PVAD by the batch method. The size of PVA granules depends mainly on the rotation speed of the mixer, which should be at least 90 rpm depending on the capacity of the reactor. The aqueous phase (a solution of incompletely saponified PVA) is loaded into the polymerizer, it is heated to 60^62°C, and VA with BP dissolved in it is fed. As the VA conversion increases, the temperature of the reaction mass is gradually raised to 65-67 C, and at the end of the process. During polymerization, the suspension is kept for 2 hours at 90-95 °C. The total duration of polymerization reaches 7-9 hours. The duration of this operation can be significantly reduced if, before conversion, 30-70% of VA is polymerized in bulk, and then the reaction mixture is dispersed in an aqueous solution of a stabilizer and the polymerization of VA is completed in suspension. The cooled suspension is centrifuged, the PVA granules are washed with water, and the polymer is dried in a rotating horizontal cylindrical dryer with air circulation. In the same way, suspension copolymers of VA with Dibutyl maleate and ethylene are obtained. In the latter case, copolymerization is carried out in a polymerizer-autoclave under pressure up to 2 MPa.

STRUCTURE AND PROPERTIES OF POLYVINYL ACETATE

Polyvinyl acetate is an amorphous, colorless, tasteless and odorless thermoplastic polymer. PVA obtained from industrial installations, has saponifiable and unsaponifiable branches formed as a result of chain transfer reactions to the polymer and monomer. The terminal groups of the PVA macrochain can be fragments of initiator molecules, as well as solvents and impurities present in the reaction mixture. The content of head-to-head structures in industrial samples is 1-2.5% (mol.).

PHYSICAL-MECHANICAL AND ELECTRICAL PROPERTIES OF POLYVINYL ACETATE

The physical and mechanical properties of PVA largely depend on the molecular weight and degree of branching of the polymer. The elastic modulus and elongation at break of linear PVA are significantly higher than that of branched PVA. At the same time, branched PVA has higher heat resistance compared to a linear polymer of the same molecular weight due to a higher concentration of structural network nodes, overlaps and interweaving of macromolecules. Tangent of the angle dielectric losses And the dielectric constant PVAs change with temperature, frequency, and moisture content of the polymer. Thus, at 20 °C tg b has a maximum value at 107-108 Hz, but with decreasing temperature* the maximum tg b shifts to the region of lower frequencies. With a decrease in current frequency to 60 Hz, the dielectric constant increases to 6.1, and after exposure to PVA at 100% relative humidity- up to 10. Being a polar polymer, PVA is highly soluble in chlorinated hydrocarbons, esters, ketones, acetic acid, dioxane, aromatic hydrocarbons, methanol, 95% ethanol; swells strongly in higher alcohols. Addition to propyl and isopropyl alcohol small amounts of water makes them PVA solvents. PVA is insoluble in water, aliphatic hydrocarbons, gasoline, kerosene, mineral oils, turpentine, carbon disulfide, glycol, glycerin. Molecular mass PVA, depending on the conditions for obtaining the polymer, varies from 10,000 to 2,000,000. The limiting viscosity number depends on the degree of PVA branching. At the same MM, branched PVA is lower than linear one. Below are the values ​​of K a a for industrial samples of PVA obtained various methods and differing in the degree of branching were measured in an acetone solution at 20 °C; The MW of PVA was determined by sedimentation in an ultracentrifuge. In a methanol solution until complete conversion. In a methanol solution until conversion is 50-60%. The plasticizing effect of various comonomers can be assessed by the reduction in Tc of VA copolymers. Ethylene is the most effective “internal” plasticizer, and also the cheapest comonomer. At a content of 40 wt% ethylene, the relative elongation reaches 2000%, while the tensile breaking stress of the films decreases to 2 MPa. Copolymers of this composition resemble rubber in properties. The introduction of vinyl chloride units into the copolymer, on the contrary, increases its rigidity. By varying the content of VA, ethylene and vinyl chloride units in the ternary copolymer, a sufficiently elastic and durable material can be obtained.

DF 51/15V, S, N- homopolymer, coarse, polyvinyl acetate dispersion, plasticized with dibutyl phthalate, stabilized with polyvinyl alcohol.

Application area:

glue for gluing wood (joining and pressing technologies);

glue for production furniture panels and other KDI (adhesive wooden products);

glue for the production of windows, doors, wood furniture;

glue for gluing paper, cardboard and corrugated cardboard packaging;

polymer dispersion for printing production (bookbinding and bookbinding works.

Mode of application:

Before use, the PVA dispersion must be thoroughly mixed. The surfaces to be bonded must be clean and dry. The dispersion can be applied using a brush, spatula, roller, suitable for application with a roller system. The dispersion should be applied evenly in a thin layer to one of the sides to be glued. The layer of dispersion applied to the surface for gluing must be evenly distributed, with an average thickness of 0.5-0.7 mm. Open exposure time - 90 seconds. and largely depends on temperature, humidity, hygroscopicity wood materials, the quality of the surfaces to be glued, the amount of glue applied. The surfaces to be glued should be tightly connected, aligned along the edges and fed into the press. The pressing time depends on the humidity and type of wood, and ambient temperature.

The dispersion is suitable for hot and cold pressing. The glued materials should be stored for some time until further use. machining to obtain sufficient strength.

Application conditions:

Bonding should be carried out at ambient temperatures from +18 to +22°C. Tool cleaning: working tools are cleaned with water or steam. Consumption: 120-200 g/m. when applied manually.

Properties:

Transport marking - according to GOST 9980.4. The dispersion is transported at a temperature not lower than -40°C. The duration of transportation of the dispersion at temperatures below 0°C should not exceed one month.

Security measures:

Premises where work is carried out with PVA dispersion DF 51/15V, S, N, must be equipped with local and general exchange supply and exhaust ventilation, ensuring the air condition of the working area in accordance with GOST 12.1.005. When working with PVA dispersion DF 51/15V, S, N it is necessary to apply means personal protection: overalls, rubber gloves, respirator, personal eye protection.

Guarantee period:

The dispersion is stored in tightly closed containers in warehouses at a temperature not lower than +5 °C. The dispersion has a shelf life of 6 months.

Package:

• plastic barrel 40 kg,
• cardboard-winding drum with polyethylene liner 50 kg,
• cubic containers 1100 kg.

When you need to glue something together, the first thing a person thinks of is the most popular PVA glue. It is found in every home and office; it is used not only for gluing paper and cardboard, but also in construction work, as well as in industry. All this is thanks to its primitive composition, which allows you to change the properties of the glue using special additives.

The history of the PVA begins back in 1912. Then the German Klat managed to obtain vinyl acetate from acetylene gas. After polymerization, this substance acquired adhesive properties. But only before the start of World War II, the American Farber was able to create industrial production polyvinyl acetate.

PVA glue: decoding and composition

PVA is a product of the chemical industry and is so named due to the main active substance in the composition stands for polyvinyl acetate. It makes up 95% of the entire composition. Polyvinyl acetate is produced by polymerizing vinyl acetate monomer using a variety of industrial methods. This substance does not dissolve in water and oil solutions and only tends to swell. Resistant to low and high temperatures, but not to temperature changes. home distinguishing feature polyvinyl acetate is that it increases adhesion between surfaces.

The rest of the PVA is made up of various additives and plasticizers. Depending on the purpose of the glue being made, EDOS, acetone and other complex substances are added to it.

Advantages over other types

Thanks to the huge number of positive properties, PVA has become so widely known. Some of them:

Specifications

PVA glue has become widespread both in everyday life, among schoolchildren, and in construction. Polyvinyl acetate has the following varieties:

• Stationery (PVA-K). Used in working with paper. It is widespread in schools and kindergartens. Non-toxic, non-resistant low temperatures and humidity. The structure is thick, odorless, and forms a surface film.
• Wallpaper (or household). Used for gluing textile, vinyl, non-woven and paper wallpaper. It is resistant to frosts of 40 degrees, and is also reliably bonded to concrete, plasterboard walls and plastered with cement mortar.
• PVA-MB (universal). PVA construction universal adhesive, technical characteristics:

1. Capable of gluing different kinds materials.
2. Used in construction work, as part of mortars water based.
3. Withstands frosts up to 20 degrees.

• PVA-M. Cheap replica of universal PVA. Capable of bonding only wood and paper. Not recommended for use on glass.

Polyvinyl acetate dispersion- glue emulsion, improved for better bonding of surfaces. It has only two types: plasticized and without plasticizers. Can be found in building mortars, household chemicals, water-dispersed paints.

Dispersion adhesive is widely used in the shoe, textile industries, etc. It is also used in the manufacture of filters for cigarettes. Moisture- and frost-resistant, has a creamy yellowish tint, viscous in composition.

Waterproof glue D class. It is used in the manufacture of wooden furniture, in the construction and repair of wood products. Moisture resistant from D1 to D4.

PVA class D3(dispersion emulsion of polyvinyl acetate of the third degree of moisture resistance). The best option for gluing wood, chipboard and on cork surfaces. It can be used in rooms with high humidity. The consistency is transparent, thick and viscous.

GOST PVA glue

According to the rules, it must have the following characteristics:

• It looks like a milky-white homogeneous mixture that does not have a pronounced odor.
• After drying, it forms a transparent viscous film.
• With the use of PVA glue, the seam of the products is strong and elastic.
• Waterproof formulations contain a polyvinyl acetate emulsion, which increases the bonding properties of polyvinyl acetate.

According to GOST, it should not contain toxins and have a strong odor. While using it White color turns into transparent and after drying it is impossible to return it to its original form.

Due to the fact that PVA glue is safe, it can be used in kindergartens, creative clubs and schools. It is distinguished and appreciated by its fire safety, as well as its ease of use, since you do not need special clothing to work with this glue.

For fast drying of glue

Many people are often puzzled by what can be done with PVA glue to dry it quickly. To do quality work, you need to know how to dry glue quickly. For small paper work and applying a thin layer of glue, it will dry completely in a maximum of 15 minutes.

On average, PVA dries in 24 hours. In order for the surfaces to be glued to fit tightly against each other, it is necessary to press them well, for example, create a press from books or clamp them in a vice for several hours.

• To ensure good adhesion of surfaces, you must first thoroughly clean them of debris and dust.
• To ensure uniform application, it is necessary to degrease the surfaces with acetone or alcohol.
• To work with PVA, it is best to use a brush or roller, since thin layer It will dry faster.
• To provide quick drying, you must use a product from a trusted manufacturer.
• PVA dries faster under moderate exposure high temperatures, so you can dry the product with a hairdryer, place it near a heat source, or put it in the microwave for a few seconds.

Reasons and rules for dilution

Polyvinyl acetate is often diluted with water. But adding water to universal, second or Moment glue is strictly prohibited, as this will disrupt the adhesive properties. You can dilute household and office glue with water. This technique allows you to reduce material consumption or restore its original consistency if the glue has thickened during storage.

Wallpaper glue presented usually in powder form. The instructions say that before working with this material, you need to dilute it in warm water (100 grams of dry powder per 1 liter of water). As a result, the solution turns out like thick sour cream, in which the roller or brush should get stuck a little. To create a primer, you need to add more water.

If, on the contrary, you need to thicken the glue, you can leave it open for a day so that the water evaporates a little.

Attention, TODAY only!

People working in the construction industry are probably aware of the use of PVA. Those for whom the name is not familiar should understand what glue dispersion is? The full abbreviation stands for: polyvinyl acetate dispersion. It has a homogeneous, viscous white consistency. The main component is industrial glue. The use of emulsion liquid in various fields presupposes the reliability and durability of the work being carried out.

What brands and their features of PVA are there?

Types of dispersions are produced in two grades: plasticized and non-plasticized. Their differences are that plasticized dispersions react negatively to sub-zero temperatures. If the substance is used under such conditions, then after defrosting the PVA cannot be used for work, since all the chemical components will not correspond to the previous consistency.

Conversely, a non-plasticized mixture has the ability to withstand more than five times of freezing and thawing processes. Wherein physical indicators will remain at the same level.

Advantages

Due to the production process by mixing vinyl acetate, emulsifiers and water in the right proportions, PVA dispersion has excellent quality moisture-repellent properties. The composition is applied quite easily. Without the use of special construction accessories. You can get by with a regular roller.

• The material does not emit toxic substances; therefore, it is classified as an environmentally friendly type.
• PVA dispersion ensures fast bonding.
• Not fire hazard.

You should pay attention to the process of applying the mixture. The speed and strength of gluing directly depends on the thickness of the layer and the material on which the glue will be applied. Can be used additional ways reliability, which look like a press on the gluing components. This will add efficiency to the process.

The choice of PVA dispersion depends on the purpose of its use. Affordable price and quality attracts Special attention to this adhesive material.

Polyvinyl acetate dispersion (GOST 18992-80) is a viscous white homogeneous liquid with a specific gravity of 1.1 g/cm3, which is a product of polymerization of vinyl acetate in aquatic environment in the presence of an emulsifier and a polymerization reaction initiator, mixed with or without a plasticizer.

PVAD is produced in different viscosity grades, in which the monomer content is standardized within 0.8%, dry residue content at least 50%, pH within 4.5-6.0, dispersion viscosity depending on the brand from 10 to 120c according to BMC, amount of plasticizer from 5 to 15%.
Plasticized PVAD is not frost-resistant, freezes at 0C and does not return to its original state after thawing. The unplasticized dispersion can withstand at least four freeze-thaw cycles and is mixed with a plasticizer immediately before use.

Polyvinyl acetate (PVA) dispersions are products with wide range of applications in a wide variety of fields. Due to their universal adhesive and binding properties, resistance to aging, high adhesive ability and environmental friendliness, polyvinyl acetate dispersions are widely used in industry, construction and everyday life. It is not for nothing that this unique product is called the material of “a thousand possibilities.”

• PVAD finds great application in the manufacture of water-based paints, adhesives, putties, mastics, primers, as a binder in polymerization compositions, fiberglass, leather, non-woven materials.
• PVA dispersions are also widely used in the printing and woodworking industries, in the production of corrugated cardboard and cardboard packaging, plasterboard and furniture, heat-insulating and fire-resistant mineral wool boards, nonwovens such as synthetic winterizer and in many other technological processes.
• Polyvinyl acetate adhesives non-waterproof, soluble in butyl acetate, perchlorethylene and other solvents, i.e. they are not completely irreversible. This serves as the basis for their use in restoration work.

The plasticized dispersion is ready for use, has practically unlimited viability, is non-toxic, is characterized by elasticity and stability of the adhesive joint, light and fungal resistance.

The glue is non-contact, it does not set immediately, so during the gluing process it is necessary to apply significant pressure, the amount of which depends on the shape of the part, the wood species, the condition of the surface to be glued, the room temperature and other factors.

The gluing process (polymerization) can be affected by acid dyes and mordants used for dyeing veneer, so PVAD should not be used for cladding and mosaic work.

The film formed when the dispersion dries has a number of valuable properties: exceptional light resistance, strength, transparency, good adhesion to hydrophilic substances, and air tightness.

Polyvinyl acetate dispersion DD50/10С
TU 2241-001-25031183-06

• Polymer emulsion for the production of water-dispersed materials: PVA adhesives, putties, mastics, VD-VA primers, water-dispersed paints.
• Adhesive for production plasterboard sheets and slabs.
• Binder for the production of mineral wool insulation.

Polyvinyl acetate dispersion DD50/15V (High viscosity)
TU 2241-001-25031183-06
Homopolymer, coarse, polyvinyl acetate dispersion, plasticized - EDOS plasticizer, stabilized with polyvinyl alcohol.

• Glue for gluing wood (joining and pressing technologies).
• Adhesive for gluing paper, cardboard and corrugated cardboard packaging.
• Polymer dispersion for printing production (binding and stitching works).

Shipment is carried out both in the buyer's container and in the seller's container. The minimum sales volume is 50 kg (hermetically sealed polyethylene flask), the product is also supplied in plastic and metal barrels and plastic containers 1100 kg. Delivery to the buyer's warehouse by seller's transport is possible.