PVA PVOH

Polyvinyl Alcohol (PVA) film is a kind of functional material with excellent properties and wide applications. Because of its unique chemical structure and physical properties, it has been widely used in many fields. The following is a detailed introduction to the properties of polyvinyl alcohol films.   1. Good transparency: PVA film has good transparency, light transmission rate of more than 90%, so that it has a wide range of uses in optical applications, such as liquid crystal display polarizer, optical filter and so on.   2. Excellent mechanical properties: PVA film has good tensile properties and rupture resistance, with high tensile strength and elongation at break. This property makes PVA film has important applications in packaging materials, reinforced fibers and other fields.   3. Good chemical resistance: PVA film has good corrosion resistance to water and organic solvents, so that it can still maintain its physical properties in high humidity environment. This makes PVA film an ideal material for water-soluble fertilizer packaging, medicine preservation and other fields.   4. Solubility: polyvinyl alcohol film has good solubility in water and is a water-soluble polymer that can be completely dissolved. This characteristic makes PVA film can be used as water-soluble packaging film, water-soluble drug coating agent and so on.   5. Thermal stability: PVA film has a high melting point and glass conversion temperature, and can maintain good physical properties at higher temperatures. This enables the application of PVA films in high temperature environments.   6. Biocompatibility: polyvinyl alcohol film is non-toxic and harmless to the human body, has good biocompatibility and will not have any harmful effects on the human body. This makes PVA film widely used in medical devices, artificial organs and other fields.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com   ElephChem Holding Limited, professional market expert in Polyvinyl Alcohol(PVA) and Vinyl Acetate–ethylene Copolymer Emulsion(VAE) with strong recognition and excellent plant facilities of international standards.

VAE emulsion is a water dispersion chemical that avoids the environmental impact of solvents and unsafe hazards. Ethylene gives polymers a softness that is permanent and impervious to the environment and climate. VAE dispersions can not only be used as excellent adhesives for paper, wood, plastics, synthetic fabrics, etc., but also can be easily mixed with thickeners, surfactants, PH regulators, plasticizers, solvents, fillers and other ingredients to make adhesives for various specific use.   1. Add thickener The water-soluble polymer thickener can increase the viscosity of the continuous phase between dispersed polymer particles, thereby increasing the viscosity of VAE emulsions. Sodium polyacrylate is an effective thickening agent for VAE emulsions. When the addition amount of thickener is less than 1%, it has little effect on the stripping strength. When 7% is added, the bond strength is significantly reduced. Carboxylic butylbenzene emulsion can significantly increase the viscosity of VAE emulsion, and improve the bonding strength of PVC, PP and other substrates. However, attention should be paid to controlling the amount of addition to prevent the viscosity from being too high.   2. Add surfactants The addition of alkyl polyoxyethylene ether and other surfactants to VAE emulsions can improve the wettability of surfaces that are difficult to wet (such as PVC films, etc.). The effective concentration is 0.1-1.0% parts surfactant per 100 parts emulsion.Adhesives manufactured with VAE emulsions generally do not require the addition of defoamer. In case of foam, add 0.1 ~ 0.2% defoamer.   3. Add PH regulator VAE emulsions are generally stable in the PH range of 3.0 to 8.5. If the PH of the mixture containing VAE emulsions is adjusted below 3.0, it results in an excessively high viscosity and is hydrolyzed more rapidly in the wet state, resulting in a lower PH. When the VAE emulsion is mixed with a dispersion solvent with a completely different PH (for example, PH 9.0), the PH of the VAE emulsion should first be adjusted above 7 with an alkaline substance. To minimize the effects caused by the difference in PH. Ammonia and sodium hydroxide are commonly used PH regulators for VAE emulsions.   4. Add plasticizer and solvent The addition of plasticizers can reduce the cost of formulations. The addition of plasticizers and solvents can also improve the performance of substrates that are difficult to bond. Four plasticizers, dibutyl phthalate, butyl phenyl phthalate, dipropylene glycol phthalate and dioctyl phthalate, were added at 15% concentration to thicken CW40-705.   5. Add stuffing In VAE dispersion-based adhesives, low-cost fillers such as clay and calcium carbonate can be added as fillers or fillers. The viscosity of emulsion can be increased by adding dry filler. First dispersed with water, then a large number of fillers can be added without making the workable viscosity too high. CW40-707 can accept more fillers than other varieties.   6. Wet strength additives The water resistance of VAE emulsions generally meets the requirements. Where improvement is needed, dialdehyde, water-soluble urine aldehyde resin (UF), melamine resin (MF) or phenolic resin can be added. Excellent water resistance can be achieved by heating curing.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com ElephChem Holding Limited, professional market expert in Polyvinyl Alcohol(PVA) and Vinyl Acetate–ethylene Copolymer Emulsion(VAE) with strong recognition and excellent plant facilities of international standards.    

Polyvinyl alcohol (PVA) is an important polymer material. Due to its good physical properties and chemical stability, it is widely used in textile, papermaking, construction, glue and other fields. It is of great significance to study the degradation mechanism and products of PVA.   Degradation mechanism of PVA: 1. Photocatalytic degradation Photocatalysis refers to the process of using electrons generated on the surface of semiconductor materials to perform chemical reactions under the action of light. PVA can be decomposed into low molecular weight products under the action of photocatalysts. 2. Thermal degradation Thermal degradation refers to the decomposition of polymer materials into low molecular weight products due to chain breakage and oxidation reactions under high temperature conditions. PVA can undergo reaction steps such as cracking, dehydration and oxidation under high temperature conditions. 3.Biodegradation Biodegradation refers to the conversion of polymer materials into low molecular weight products through metabolic processes in organisms such as microorganisms or enzymes. PVA can be broken down into low molecular weight products through microbial metabolism.   Main degradation products of PVA: 1.Ethanol Ethanol is one of the main products of thermal degradation of PVA. It is generated due to the reaction between the hydroxyl group and the aldehyde group formed by the cleavage of the ester bond within the PVA molecule to generate alcohols. 2.Formaldehyde Formaldehyde is also one of the main products of thermal degradation of PVA. It is generated due to the reaction of the hydroxyl group formed by the cleavage of the ester bond within the PVA molecule and the aldehyde group to form ethyl formate, which is then decarboxylated to form formaldehyde. 3.Ethylene Ethylene is one of the products of photocatalytic and thermal degradation of PVA. In photocatalytic degradation, PVA will undergo chain scission after being exposed to ultraviolet light, forming hydrocarbon free radicals, and then an addition reaction will occur to generate ethylene. In thermal degradation, chain scission and dehydration reactions occur within PVA molecules under high temperature conditions, ultimately generating ethylene. 4.Carbon dioxide Carbon dioxide is one of the main products produced during biodegradation. During microbial metabolism, PVA is converted into low molecular weight products such as carbon dioxide and water. 5. Acetic acid Acetic acid is one of the main products produced during biodegradation. During microbial metabolism, PVA is converted into low molecular weight products such as acetic acid and water.   By studying the degradation mechanism and main degradation products of PVA, we can provide a theoretical basis for improving the environmental friendliness of PVA. At the same time, it can also provide reference for the research of polymer materials.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com ElephChem Holding Limited, professional market expert in Polyvinyl Alcohol(PVA) and Vinyl Acetate–ethylene Copolymer Emulsion(VAE) with strong recognition and excellent plant facilities of international standards.

Into the late 1980s, High-count, lightweight wool products in the market has become a hot spot. The momentum is fast. The weight of men's fabric has been reduced by about 20% to 30%, the weight of women's fabric has been reduced by 10% to 15%, and the quality of wool has been increased from 64/66 to 66/70. For high-count lightweight products, in addition to the use of chemical fiber blending to increase the number of spinning, pure wool products use more than 70 ultrafine wool. According to the information of the International Wool Bureau, the average diameter of less than 19μm of wool production accounted for only 5.44% of the total output of Australian wool, while 20~30μm of wool production accounted for 66.6% of the total output, the price difference between the two is more than 50%. Therefore, the use of ultrafine wool spinning high-count lightweight products, not only the number of raw materials is small and expensive.   In order to solve this problem, we use a new type of polyvinyl alcohol (PVA) fiber, that is, water-soluble fiber, mixed with medium-fine wool, after finishing to remove the PVA fiber in the fabric, the same use of ultrafine wool spinning High-count, lightweight products, and the cost is low.   The removal of PVA fibers should be carried out before finishing the fabric. That is, the PVA fiber is removed in hot water first, and then other finishing. Since wool can not be treated at high temperature for a long time, the lower the dissolution temperature of the selected PVA fiber, the better, but according to the process of producing PVA fiber in the chemical fiber factory, the dissolution temperature is reduced, the fiber strength is reduced, and the spinning break is increased, and the fiber strength can meet the spinning requirements when the water solubility temperature is 70~80° C, the spinning break is low.   For the PVA fiber in the fabric, because the infiltration of water molecules is from the surface to the inside, the PVA fiber on the surface of the fabric is first dissolved, and then the PVA inside the fabric is dissolved. Removing the PVA fiber inside the fabric is more difficult than removing the loose fiber, and the water temperature must be higher than its dissolution temperature. The bath ratio is larger and longer.   PVA fiber and wool mixed spinning thin products process route: PVA fiber Strip & Wool strip - Mixed strip a pre-spinning - post-spinning → Weaving → post-finishing (removing PVA fiber)→ pure wool high-count lightweight products.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com ElephChem Holding Limited, professional market expert in Polyvinyl Alcohol(PVA) and Vinyl Acetate–ethylene Copolymer Emulsion(VAE) with strong recognition and excellent plant facilities of international standards.  

Vinylon is the trade name of polyvinyl acetal fiber, also known as Vinylon. Its performance is close to cotton, known as 'synthetic cotton', is the largest variety of existing synthetic fibers in hygroscopicity. It is not easy to ignite, near the flame melting contraction, there is a little flame at the top of the burning, when the fiber is melted into a gel, the flame becomes larger, there is thick black smoke, emitting bitter aroma, and the black small beaded particles are left after burning, which can be crushed by fingers.   Vinylon is the most hygroscopic variety in synthetic fibers, with a hygroscopic rate of 4.5% to 5%, close to cotton (8%). Vinylon is soft and warm, and its relative density is smaller than cotton, so the same weight of Vinylon with cotton can weave more clothing. Its thermal conductivity is low, so the warmth is good. The wear resistance and strength of Vinylon are also better than cotton, so Vinylon can be blended with cotton in many ways to save cotton. Vinylon is mainly used in the production of garments, cotton sweaters, pants, sweatshirts and other knitted fabrics, can also be used in canvas, fishing nets, surgical stitches, bicycle tire cord, filter materials. More and cotton blend: muslin, poplin, corduroy, underwear, canvas, tarps, packaging materials, work clothes, etc.   The main component of Vinylon is polyvinyl alcohol(PVA), but vinyl alcohol is unstable, generally with stable performance of vinyl alcohol acetate (that is, vinyl acetate) as a monomer polymerization, and then the generated polyvinyl acetate alcohol hydrolysis to polyvinyl alcohol, spinning and then treated with formaldehyde, in the polymer chain to introduce a six-membered ring structure to generate polyvinyl formaldehyde, enhance its strength. To get water resistant Vinylon.   The manufacture of industrial vinylon fiber is to dissolve polyvinyl alcohol in water to produce about 15% aqueous solution, through the spinneret with a diameter of about 0.07 mm, in the saturated sodium sulfate aqueous solution solidification bath to produce fiber, and then stretching and heat treatment to improve strength and heat resistance; Then in the presence of catalyst sulfuric acid, acetal reaction with formaldehyde, the temperature is about 70℃, the time is 20 to 30 minutes, after washing, oil to obtain Vinylon fiber. Vinylon fiber has short fiber, tow and filament and other varieties, of which cotton type short fiber and tow are the most common.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com ElephChem Holding Limited, professional market expert in Polyvinyl Alcohol(PVA) and Vinyl Acetate–ethylene Copolymer Emulsion(VAE) with strong recognition and excellent plant facilities of international standards.

The different mesh numbers of PVA should be selected according to the specific application needs, to ensure the best effect. The mesh number of PVA indicates its particle size, the larger the mesh number, the smaller the particle diameter. For example, ‌120 purpose polyvinyl alcohol particle size is smaller, ‌under the action of surfactants, can be better adsorbed and coated by liquid, the lubricity, and other properties are better than 80 purpose polyvinyl alcohol. ‌, therefore, ‌ when it is necessary to use polyvinyl alcohol, ‌ should be selected according to the specific application needs of different mesh of polyvinyl alcohol. In addition, the common mesh of ‌ polyvinyl alcohol includes 12 mesh, 20 mesh, 25 mesh, ‌80 mesh and 120 mesh, ‌ grinding into powder can improve the dissolution rate of polyvinyl alcohol, ‌ but not the finer the better, the powder will lump as long as it is soaked with water, especially when the dosage is large. On the contrary, it is not conducive to the dissolution of PVA.    When dissolving more than 80 mesh PVA powder, pay attention to the way of adding, need to stir quickly, add slowly, to prevent more powder together when encountering water. Dissolved larger particles of powder below 80 mesh PVA basically will not lump, but at room temperature dissolution is slower, you can stir or increase the dissolution temperature, thereby accelerating the dissolution of PVA.   Therefore, the appropriate mesh number should be selected according to the different requirements of the product and the situation of the reactor of the existing equipment.   ElephChem can provide a variety of PVA powder with different mesh sizes, welcome to consult: Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com ElephChem Holding Limited, professional market expert in Polyvinyl Alcohol(PVA) and Vinyl Acetate–ethylene Copolymer Emulsion(VAE) with strong recognition and excellent plant facilities of international standards.

Using the existing coating machine, dry composite machine and other equipment of domestic flexible packaging enterprises, after coating PVA coating solution of only 0.5g/m2 ~ 0.8g/m2 (dry base) on the film with qualified surface tension (such as PET, BOPP, CPP, PE and other films), The oxygen permeability of the film is less than 2cm3/ (m2·24h·0.1MPa), or even less than 0.5cm3/ (m2·24h·0.1MPa). Obviously, the oxygen resistance of the product has been significantly better than the five-layer co-extruded film with EVOH as a barrier layer and PVDC high barrier coating film, which is close to the oxygen resistance of aluminum foil. Advantages1, high cost performanceThe production cost of modified PVA coated high barrier film is much lower than the production cost of paper aluminum-plastic composite and aluminum-plastic composite structure packaging materials, and also lower than the cost of PVDC coated composite film. 2, excellent oxygen resistanceThe modified polyvinyl alcohol (PVOH) composite film has good barrier property to oxygen, nitrogen, hydrogen and carbon dioxide, and its oxygen inhibition property is much better than PVDC composite film. 3, excellent perfuming performanceIt can maintain the original flavor of the food in the bag for a long time, and at the same time, it can effectively prevent the odor outside the packaging material from entering the bag. 4, excellent environmental protection materialsPVA coating liquid is composed of carbon, oxygen, hydrogen and silicon, which can be degraded, recycled and reused, and does not produce toxic gases after combustion. It is an ideal packaging material.   ElephChem Holding Limited, professional market expert in Polyvinyl Alcohol(PVA) and Vinyl Acetate–ethylene Copolymer Emulsion(VAE) with strong recognition and excellent plant facilities of international standards.

Polyvinyl alcohol defoamer is a kind of surfactants commonly used in the chemical field, and it is widely used in the chemical industry. Its main role is in the production process, can effectively reduce the foaming phenomenon, also known as foaming agent or foam inhibitor.   Properties of polyvinyl alcohol defoamer 1. With low surface tension, it can effectively destroy the tension on the surface of the liquid, so that the liquid molecules repel each other, and the molecular combination will no longer occur to produce foam.2.Polyvinyl alcohol defoamer has good dispersion performance, which can re-disperse dispersed bubbles in the liquid, thereby avoiding foam deposition and reducing energy waste.3. PVA defoamer can form a relatively stable dispersed liquid system, making its distribution in the liquid more uniform, thereby reducing the generation of foam.4. Its role is to change the interaction force between molecules, and the physical and chemical properties of the solution have no obvious relationship, will not affect the composition of the solution and chemical reaction.   The role of PVA defoamer in production 1. Reduce energy consumptionThe application of PVA defoamer can effectively reduce the resistance of air and bubbles to liquid, reduce the consumption of pumping energy and stirring energy, and thus save energy.2. Improve production efficiencyIn some special occasions, the generation of foam will have a negative impact on production efficiency, the use of PVA defoamer can effectively reduce the generation of foam and improve production efficiency.3. Improve product qualityThe use of polyvinyl alcohol defoamer can effectively control the foam generation, reduce the tension of the liquid surface, make the product surface more flat and smooth, so as to improve the product quality. To sum up, PVA defoamer is one of the excellent surfactants, which is widely used in various industrial fields. In practical application, we should choose the corresponding defoamer according to the specific production needs to achieve the best effect.   ElephChem Holding Limited, professional market expert in Polyvinyl Alcohol(PVA) and Vinyl Acetate–ethylene Copolymer Emulsion(VAE) with strong recognition and excellent plant facilities of international standards.

Polyvinyl alcohol 2688 is a polymer compound with the formula (C2H40)n, where the value of n is greater than or equal to 1000. It is a polymer in chemical structure, its molecular weight is very high, and it has very special physical and chemical properties. The most important thing about the properties of PVA 2688 is its viscosity. Viscosity is a basic property of liquid fluidity and describes the degree of viscosity of a liquid. The viscosity of PVA 2688 is often used to describe its viscosity in aqueous solutions, and its value is generally measured at 20 ° C.    PVA 2688 has a viscosity of up to 50(mPa.s), which makes it a very viscous polymer compound. Due to its high molecular weight, the interaction between molecular chains is very strong, so the molecular chain of PVA 2688 is difficult to flow, and its viscosity is high. At the same time, because the polyvinyl alcohol 2688 molecule contains a large number of hydroxyl (-OH) groups, these groups can form hydrogen bonds with water molecules, so that it has good solubility in water.   The viscosity of PVA 2688 directly affects its performance in practical applications, so it is usually necessary to select an appropriate viscosity range. According to the actual process and needs, different viscosities of polyvinyl alcohol 2688 can be selected for application. The high viscosity of PVA 2688 makes it widely used in industrial and agricultural fields. For example, it is used in the manufacture of textiles, paper, paint adhesives and other products. In addition, it can also be used for the preparation of certain pharmaceuticals, daily chemical supplies and so on. Due to its good solubility in water, it is also used as a precipitator, dispersant, lubricant, etc., and PVA 2688 has a wide range of application prospects.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com   ElephChem Holding Limited, professional market expert in Polyvinyl Alcohol(PVA) and Vinyl Acetate–ethylene Copolymer Emulsion(VAE) with strong recognition and excellent plant facilities of international standards.

Polyvinyl alcohol 1788 is a colorless, transparent, viscous polymer compound consisting of alternating arrangements of vinyl and hydroxyl units. It is often used in the preparation of glue, coatings, textiles, medicine and other fields.   Polyvinyl alcohol 1788 has good solubility, can be dissolved in water, can also be dissolved in alcohols, esters and other organic solvents. Its solubility decreases with the increase of molecular weight. In dry air, PVA 1788 is relatively stable, but it breaks down in sunlight.   Polyvinyl alcohol 1788 is an important polymer material, which is widely used in various fields. The main uses of PVA 1788 are as follows: 1. Glue preparationPVA 1788 can be used to prepare various glues, such as woodworking glue, paper glue and so on. Dissolve PVA 1788 in water, then add crosslinking agent and auxiliary agent, after stirring, filtration, defoaming and other process steps, you can get glue. 2. Coating preparationPVA 1788 can be used to prepare various coatings, such as wall coatings, wood coatings and so on. The polyvinyl alcohol 1788 is dissolved in water, and then added pigments, fillers, auxiliaries, etc., after mixing, grinding, filtration and other process steps, the paint can be obtained. 3. Textile processingPVA 1788 can be used in textile processing, such as the processing and printing of cellulose fibers. Dissolve PVA 1788 in water, then add dyes, additives, etc., after soaking, drying and other process steps, dyed cellulose fiber can be obtained. 4. The field of medicinePVA 1788 can be used to prepare medicine, such as oral medicine, injections, eye drops and so on. Dissolve PVA 1788 in water, then add drugs, auxiliaries, etc., after mixing, filtration, sterilization and other process steps, you can get the drug.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com   ElephChem Holding Limited, professional market expert in Polyvinyl Alcohol(PVA) and Vinyl Acetate–ethylene Copolymer Emulsion(VAE) with strong recognition and excellent plant facilities of international standards.

Dispersion polymerization is another kind of heterogeneous free radical polymerization of alene monomers except suspension polymerization and emulsion polymerization. Dispersion polymerization can be regarded as a polymerization between suspension polymerization and emulsion polymerization, and its characteristics are as follows: 1) Water or non-water solvent can be used as the medium. When water is used as a medium, the monomer must be insoluble in water or substantially insoluble in water.2) The dispersion of monomers in water is achieved by intense agitation, and the protective colloid added to the system plays a role in preventing the agglomeration of dispersed phases.3) Water-soluble initiators are required for dispersion polymerization with water as the medium.   In form, dispersion polymerization has many similarities with emulsion polymerization. But there are clear differences. Dispersion polymerization, for example, does not use typical emulsifiers but uses protective colloid to stabilize the polymerization system; The particles obtained by polymerization are larger than those obtained by emulsion polymerization. Let's wait.The polymerization of vinyl acetate in water with polyvinyl alcohol as a protective colloid is a typical dispersion polymerization. Vinyl acetate is a water-soluble monomer with a solubility of about 2.5% in water at room temperature and is easily hydrolyzed. The hydrolysis product acetic acid can seriously interfere with the normal process of polymerization. Therefore, the dispersion polymerization of vinyl acetate has more complicated factors than the common emulsion polymerization. It is believed that the dispersion polymerization of vinyl acetate does not occur in micelles, but the monomer dissolved in water is first polymerized, and when the molecular weight reaches a certain level, the polymer precipitates from the water to form latex particles on the protective colloid. In order to improve the stability of the polymerization system and products, an appropriate amount of emulsifier is added in the dispersion polymerization of vinyl acetate, but the role of emulsifier in polymerization is auxiliary.   Attentions： PVA usually has two specifications of 1788 and 1799 (17 indicates a degree of polymerization of 1700, 88 and 99 indicate an alcoholysis degree of 88% and 99%, respectively). When used as a dispersion polymerization protective colloid, it is best to use 1788, and the resulting product has good stability.2. In the polymerization process, the monomer droplet acceleration should be slow and not fast. Generally, a slight reflux in the condenser is appropriate.3. The boiling point of vinyl acetate is between 70-75℃. After adding drops, the heating rate should be slow, too fast and easy to caking.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com   ElephChem Holding Limited, professional market expert in Polyvinyl Alcohol(PVA) and Vinyl Acetate–ethylene Copolymer Emulsion(VAE) with strong recognition and excellent plant facilities of international standards.

The production process of polyvinyl alcohol can be divided into ethylene method and acetylene method according to raw materials. Acetylene synthesis can be divided into calcium carbide acetylene synthesis and natural gas cracking acetylene synthesis according to the different sources of raw materials. Calcium carbide acetylene synthesis, the first to achieve industrial production. Due to the high energy consumption, low quality and high cost of the products of this process route, the impurities generated by the production process pollute the environment is also more serious, and the lack of market competitiveness is gradually eliminated. In areas rich in natural gas, coal and electric power, natural gas acetylene synthesis is still vital.The process of synthesis of polyvinyl alcohol by ethylene method includes five steps: obtaining ethylene and synthesis of vinyl acetate, rectification, polymerization, alcoholysis of polyvinyl acetate (PVAc), recovery of acetic acid and methanol.   Vinyl acetate polymerization:   After preheating, ethylene acetate was mixed with solvent methanol and initiator azodiisobutyronitrile and sent to two tandem polymerization reactors for polymerization at 66 ~ 68℃ and atmospheric pressure. After polymerization for 4 ~ 6H, about 2/3 of vinyl acetate was polymerized into polyvinyl acetate. The heat generated by the polymerization reaction can be carried away by the evaporation of methanol, and the methanol vapor is condensed and returned to the polymerization kettle. The polymerization liquid is sent to the monomer to blow out the tower, and the unpolymerized vinyl acetate is blown out with methanol vapor. The ethylene acetate and methanol blown by the monomer blowout tower are separated and distilled, recovered and recycled. The polymerization solution was sent to the alcoholysis section for alcoholysis with methanol adjusted to 33% polyvinyl acetate.   Polyvinyl acetate alcoholysis: Polyvinyl acetate and sodium hydroxide methanol solution were mixed into a high-speed mixer at the ratio of polyvinyl acetate: methanol: sodium hydroxide: water at 1∶2∶0.01∶0.002 at the same time, and then entered the belt alcoholysis machine for alcoholysis at 50℃. The belt was moved at a speed of 1.1 ~ 1.2m/min, and the alcoholysis was completed in about 4 minutes. To obtain cured polyvinyl alcohol. After the solvent was removed by grinding, pressing and drying, the finished polyvinyl alcohol was obtained.   Recovery of methyl acetate: The extruded liquid contains a lot of methyl acetate and methanol. First, the azeotrope of methyl acetate and methanol is steamed in the azeotrope distillation column, and the bottom of the column is methanol aqueous solution. Methyl acetate and methanol azeotrope into the water extraction separation column and mixed with water, the top of the column separated methyl acetate, the bottom of the column is methanol aqueous solution. Methyl acetate was catalyzed by ion exchange resin in a hydrolyzer to obtain a mixture of acetic acid and methanol. The mixture is sent to a hydrolysate distillation column, where methanol and unhydrolyzed methyl acetate are steamed out and fed into a water extraction separation column. The bottom of the hydrolysate distillation column is dilute acetic acid, which is obtained after being sent to the dilute acetic acid concentration column to remove the water. The methanol aqueous solution obtained from the bottom of the azeotropic distillation tower and the water extraction separation tower can be reused by steaming the methanol in the methanol distillation tower.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com ElephChem Holding Limited, professional market expert in Polyvinyl Alcohol(PVA) and Vinyl Acetate–ethylene Copolymer Emulsion(VAE) with strong recognition and excellent plant facilities of international standards.