KR0128722B1 - Process for the production in watery emulsion of blends of polyvinylic alcohol - Google Patents

Abstract

Processes for preparing W-type emulsions of two or more polyvinyl alcohols (PVA) with different saponification values (NS) to obtain the product of polyvinylchloride (PVC-S) in water suspensions have a K value between 30 and 110. At least a first polyvinyl acetate (PVAc) with a molecular weight measured on the 50th day is used, and the technique of alcoholic acid or base is used to determine the PV value between 598 and 135, preferably between 598 and 312, optimally up to 511. Performing a trans-esterification reaction, wherein the weight ratio of at least the second PVAc with a molecular weight measured when the K value is between 10 and 90, preferably between 25 and 10 optimally between 25 and 50 is set at 0.1 relative to the weight ratio of the first PVAc. Preferably up to 5 times 0.7 times, preferably between 280 and 95 where each PVA is dissolved in water in the final alcohol solution, preferably between at least 1 PVA having a saponifier value of 230 and 598 and 312 insoluble in water Stopping alcohol decomposition to occur as a result of complete mixing to obtain at least a second PVA with a saponifier of 480 and in the form of particulates with granular metric distribution between 0.01 microns and 10 microns during or at the end of alcohol decomposition. And distilling off the residual solvent adjacent to water after alcohol decomposition in the range of obtaining coagulation in water of the second PVA.

Description

Process for preparing aqueous emulsion of polyvinyl alcohol blends

The present invention relates to a process for the preparation of an aqueous emulsion of polyvinyl alcohol having different saponification numbers. Specifically, the present invention is used for the synthesis of polyvinyl chloride (PVC-S) in an aqueous suspension in an industrial scale. It relates to a method for producing polyvinyl alcohol (PVa).

In this specification, the terminology will be used after evaluating and quantifying the characteristics of used and manufactured products.

NS is the amount of potassium hydrate required to hydrolyze 1 g of sample in mg. For example, the acid level of this value is operated in the following order: 1 g of sample is quantified and dissolved in 50 ml of water and 50 ml of methyl alcohol: 1 ml of phenolphthalein alcohol solution is added thereto again: 100 ml of KOH N / 10 solution is added to heat the product under reflux. After titrating the specified HCl N / 10 to the product, the number of mg of KOH used for hydrolysis is calculated stoichiometrically.

The molecular weight of polyvinylacetate (PVAc) is expressed as the K value of PVAc determined by measuring the viscosity relative to the PVAc solution in acetone. The relative viscosity is converted into K values by a table representing the predetermined values. The method is as follows: 1 g of completely dried sample is quantified, dissolved in 100 ml of acetone and the precipitation time of the solution is measured at 25 ° C. using the Viscosimeter Ostwald series 50. The settling time ratio of the solution and pure acetone gives a relative viscosity value. Polyvinyl alcohol having properties that are remarkably distinguishable in terms of solubility and insolubility in water to prepare PVC-S having optimal morphological properties in the formulation of polymerizing vinyl chloride monomer (VCM) in an aqueous suspension. It is known to use suspension based suspension systems.

PVAs with a value of less than 280 are soluble in water and are commonly referred to as primary suspending agents.

PVAs with a value of at least 280 are partially insoluble in water and are commonly referred to as secondary suspending agents. In the preparation of PVC-S, a PVA of the second suspension type without residues of methyl alcohol, methyl acetate, ethyl alcohol and ethyl acetate has a diameter of fine particles of less than 10 μm and an NS value of at least 280, preferably at least 480. It is very important to use in the form of an aqueous emulsion.

From the start of the polymerization, when the second suspending fine particles in the reactant have a complete distribution, the main properties of the PVC-S, i.e. the distribution of porosity in the PVC-S granules, the apparent viscosity, usually fish-eye The amount, particle size distribution, volume resistance, etc., of all or part of the gelled granules, referred to as the eye) is locally improved.

EP-0123364 (Stamicarbon) discloses a process for producing PVC-S using an aqueous dispersion of polyvinyl alcohol as a suspension system, but the patent does not disclose a process for producing an aqueous dispersion.

IT-83315-A-86 discloses a process for hydrolysis of PVAc microparticles previously prepared in aqueous emulsion. The method uses sodium hydroxide as the basic catalyst for the hydrolysis reaction, and simultaneously removes the salt produced as a result of the hydrolysis by ultrafiltration.

However, this method only allows the use of the direct hydrolysis technique of PVAc, which is referred to in the literature as RANDOM, of -OH groups, which can only be prepared by acidic alcoholic decomposition in the presence of methylalcohol or ethylalcohol. PVAc is prepared without alternating distribution.

In addition, during the ultrafiltration process used to remove large amounts of sodium acetate resulting from the basic hydrolysis process, the viscosity of the 4% aqueous solution at a temperature of 20 ° C. at a temperature of 20 ° C. using a Viscosimeter Hoeppler through the membrane is low. Release of water containing polyvinyl alcohol, measured to be 3.5 mPa · s (centipoise). The leakage of polyvinyl alcohol into the wastewater results in an increase in the manufacturing cost and the cost of biologically treating the wastewater itself.

It is an object of the present invention to provide an improved process for the production of polyvinyl alcohols which can be obtained by both acidic and basic alcoholic decompositions, which have different impacts, are inexpensive and reproducible.

As described in the claims of the present invention, the present invention provides a process for the preparation of a PVA blend in an aqueous emulsion for use in the production of PVC-S, consisting of the following steps: i) a molecular weight of 30 to 110 K, preferably Preferably 50 K and using an acid or base catalyst in the presence of ethyl alcohol or methyl alcohol and carrying out the hydroalcoholic reaction of PVAc until the influx is 598 to 135, preferably 598 to 312, most preferably 511. Doing; ii) dropping a second PVAc having a molecular weight of 10 to 90 K, preferably 10 to 50 K, most preferably 25 K by weight of 0.1 to 5 times, preferably 0.7 times, based on the first PVAc; iii) stopping the alcohol breakdown reaction so that each PVA in the final alcohol solution is thoroughly mixed so that (a) the water-soluble first PVA having a value of 280 to 95, preferably 230, and (b) Obtaining a water-insoluble three 2PVA of 598 to 312, preferably 480; And iv) distilling the residual solvent during or at the end of the dialcohol decomposition reaction and adding water after the dialcohol decomposition reaction to condense the second PVA into fine particles having a particle size distribution of 0.01 μm to 10 μm in water to obtain an aqueous emulsion.

The process of the present invention provides a novel process for preparing aqueous emulsions of PVC having different influences, based on a novel process of simultaneously alcoholic decomposition of two or more PVAc. This method also makes it possible to maintain the basic characteristics of the first and second suspending agents which constitute the emulsion.

As a result, a novel product is prepared which can be used as an initial loading in the polymerization of vinyl chloride monomer aqueous suspension and which gives a beneficial effect on the morphological properties of the PVC-S produced. This has been confirmed by the inventors who have studied and applied the preparations according to the present invention with different PVC-S polymerization techniques, and the inventors have compared the known primary and secondary suspending agents used in the production of the PVC-S. The following marvels have been developed:

The preparations of the present invention can be prepared using basic gaalcohol degradation techniques, acidic alcoholic decomposition techniques, or different combinations thereof.

The preparations of the invention serve a dual function as primary and secondary suspending agents and are capable of producing all types of known PVC-S at a high qualitative level.

-The preparation of the present invention has a strong anti-expansion and foam suppression of the material during the polymerization reaction, and can complete the reaction for a very short time without harmful clogging of the upper part of the autoclave and the reflux condenser. ; In the case of dropping a large amount of formulated products for the purpose of improving the thermal stability of the produced PVC-S, the inventors have found that the viscosity of the material during the polymerization reaction is raised to a dangerous level or the heat exchange of the autoclave is significantly improved. Could not be observed.

The preparation of the present invention is compatible with the aqueous solution of all the primary suspending agents used in the manufacture of PVC-S and has miscibility, so as to improve the qualitative characteristics of the PVC-S and PVC-S manufacturing technology itself as follows. Can be used in different combinations of formulations: The preparations of the invention are completely stable at temperatures from + 60 ° C to -30 ° C.

The preparations of the present invention do not cause cracking in the emulsion, even if frozen or thawed, leading to precipitation of the non-aqueous fraction; The preparations of the present invention can produce stable aqueous emulsions of peroxide catalysts in solid or liquid form used in the production of PVC-S even at temperatures below 0 ° C.

If the product of the present invention is placed directly in the hot water of the polymerization dropping line of the autoclave at a temperature of 65-70 ° C., no sticky deposits are observed on the conduit, and even if it is added to the autoclave at a high initial temperature, the PVC- The quality of S does not deteriorate.

Advantages of the production method of the present invention for producing PVC-S are as follows:

-A minimum amount of salts remaining and no methyl alcohol or ethyl alcohol residues, thus producing PVC-S with high volume resistance and suitable for use in hydrolysis; The different combination types of PVA itself and the alcoholic degradation grades making up the emulsion allow for the control of all properties of PVC-S such as internal porosity, apparent density, particle size distribution, thermal stability and the like.

The process of the present invention is also characterized in that the catalyst is sulfuric acid and / or sodium methylate and / or sodium hydroxide, each using 0.05 to 8 parts by weight of the catalyst independently of PVAc.

The alcohol used for the dialcohol decomposition reaction is methyl alcohol or ethyl alcohol, which is used in an amount of 0.2 to 30 times, preferably 3 times, by weight based on PVAc.

In the present invention, since the first and second suspensions and peroxide catalysts are used to produce PVC-S, the automatic dropping technique of the polymerization reactor is significantly simplified and perfect in the dropping technique using a closed manhole. In fact, the emulsions of the present invention can be easily pumped into the loading line of the autoclave and likewise do not generate dangerous deposits.

In the production equipment of PVC-S, the use of the preparation of the present invention allows for continuous improvement of the production volume, and also significantly improves the working environment and the surrounding ecological environment in which the plant is established. In summary, these advantages are as follows:

-Loading on an autoclave with a sealed manhole;

-Reduce the emission of VCM gas caused by frequent opening of the manhole.

Reduces the amount of air in the recovered VCM, preventing unwanted amounts of VCM-recovered gas from leaking into the atmosphere, identified as a potent carcinogenic substance worldwide.

Safe operation and accumulation of catalyst

EXAMPLES Aqueous Emulsion Process of Polyvinyl Alcohols with Different Hydrolysis Values

For the next test, a reactor of 580I capacity was used, the inner surface of which was made of glass and equipped with an anchor-shaped stirrer (revs 10-1000) and a cooling jacket. The upper part is connected to a reflux condenser made of glass through a gate of three, which is provided with a three way valve for continuous extraction of the condensate and has an exchange surface area of 1 m ² . PVC emulsion was analyzed by the following method:

Determination of percentage of active substance

The percentage (%) of active material was determined by a simple method of evaporating 5 g of the sample enclosed in an aluminum capsule at 110 ° C. for 3 hours in a vented stove.

Viscosity of PVC aqueous solution at 20 ℃ (unit: centipoise)

An aqueous solution containing 4% of the active substance sample to be analyzed was prepared and the precipitation time at 20 ° C. was measured using a Viscometer Hoemeter.

Using the comparison table provided for the guidance of the Viscometer, the viscosity value of the solution can be estimated.

Type of Gaal Alcohol Degradation BLOCKY-RANDOM

Nuclear magnetic resonance (NMR) spectroscopy was used to determine the distribution type of hydroxyl group (OH) in the PVA chain.

Diameter Measurement of Partially Hydrolyzed PVAc Particles

A particle size distribution of water-insoluble PVAc fine particles was determined using a device commonly called COLTER-CONNTER.

A 250Kg aqueous solution containing 13Kg polyvinyl alcohol with a NS value of 137 and a viscosity of 4% in 45 mPa · s of water, 25Kg of vinyl acetate monomer (VAM) and 0.03Kg of ammonium persulfate were loaded into the reactor. The product is polymerized to a temperature of 63 ° C. for 5400 seconds (90 minutes). Again, an additional 125 Kg of VAM was supplied for 3 hours.

After loading, the temperature is raised to 95 ° C. over 2 hours to complete the process of converting the VAM in the aqueous emulsion to polyvinylacetate (PVAc). In the analysis, its molecular weight or K value is 102.

When the emulsion is discharged, 120 Kg of product remains in the reactor. 250 Kg of methyl alcohol and 2.5 Kg of concentrated H2SO4 ((d.) G / ml 1/83) are added in sequence at 40 ° C for 20 minutes. Finally, the material is adjusted to reflux temperature, and then the acidic alcoholic decomposition process is carried out for 9 hours. Within 600 seconds (10 minutes), a methanolic solution containing 50% polyvinyl acetate and having a K value of 25 is added (this product can be prepared using either a solution polymerization method or a block synthesis method). By refluxing at all times, the distillate consisting of the methyl methyl acetate alcohol azeotrope formed during the decomposition of the alcohol is removed and the operation is continued for another 9 hours so that the total removal amount of the solvent is 170 Kg.

2 Kg of NaOH dissolved in 20 Kg of water was used to stop the alcohol degradation. The methyl alcohol residue was removed by gradual change using the same amount of water. The product was diluted with water to have a total solids content of 23%.

In the final release process, a PVA fraction with an NS value of 480 and 30% of the total polyvinyl alcohol content precipitates in the form of emulsified particulates in an aqueous means containing a large amount of polyvinyl alcohol having a diameter of 0.01 to 10 μm and an NS value of 230. do. The final emulsion was chromatographed and found to be free of residual solvents, white and stable at -25 to + 60 ° C. Tests dispersed in pure water or in aqueous solutions of cellulose, acrylic and polyvinyl alcohol types have demonstrated their complete dispersibility and the absence of deposits or formation of viscous substances on the bottom. In order to continue the polymerization test of PVC-S on the emulsion, the emulsion was given a code PVA-AI.

The gaalcohol digestion technique used in the process for producing PVC-A1, using a combination of methylalcohol-water-sulfuric acid, provides a distribution of hydroxyl groups in the PVA chain, referred to in the literature as Completely Random. [Polyvinyl Alcohol Properties and Applications, Chapter 4, p. 93: CAFINCH, Crode POLIMERS LIMITED London].

Example 2

160 kg of VAM, 35 kg of methyl alcohol and 5 kg of benzoyl peroxide are added dropwise into the reactor. The polymerization was continued for 7 hours at reflux temperature, finally converting the polyvinyl acetate to 99%. The molecular weight or K value is 49. The material is again added 250 kg of sulfuric acid (g / ml (d.) 1.83). The product is refluxed and left for 8 hours.

40 kg of a methanolic solution of the same polyvinylacetate (K = 25) as used in Example 1 is loaded.

A total of 100 kg of methyl acetate-methyl alcohol azeotrope was extracted for 15 hours. The reaction was stopped with 0.2 Kg of NaOH dissolved in 50 l of water. As in Example 1, the methyl alcohol residue was removed and diluted with water to 30% solids.

As in Example 1, the emulsion was assigned code number PVA-A2, which is 70pp of water-soluble PVA with an NS value of 230 and 30pp of water-insoluble PVA with an NS value of 480. Gacoalcoholization techniques using anhydrous methyl alcohol and sulfuric acid provided a distribution of -OH groups classified as RANDOM in the literature.

Example 3

In the reactor, 200Kg methanol solution containing 26% PVAc (K = 50) of the same type as in Example 2, and 30Kg NaOH solution consisting of 27Kg metal alcohol, 2.5kg water and 0.3Kg NaOH in order Drop it.

The material is held at reflux until the temperature drops to 0.7 ° C. Thereafter, 50 Kg of a solution of PVAc (K = 25) in methyl alcohol of the same type as described in Examples 1 and 2 were added dropwise. A total of 100 Kg of methyl acetate-methyl alcohol azeotrope is extracted for 8 hours.

0.6Kg of acetic acid (99%) is added so that the pH is 6.5. In Examples 1 and 2, methyl alcohol was distilled off to continue the reaction and water was added until the final solids percentage was 30%.

As in the above embodiments, the emulsion was designated code number PVC-A3, whose composition is as follows: 65 p.p with NS of 230 and 10 mPa.s (cps) (4% in water). PVA; And emulsified in the form of fine particles having a diameter of 0.01 to 10 μm of PNA of 35 p.p having an NS of 480. The dialcohol decomposition technique used in the preparation of the emulsion PVA-A3 consists of methyl alcohol + sodium hydroxide + water, which is referred to in the literature as BLOCKY.

The distribution of certain types of hydroxyl groups, which can be easily demonstrated by NMR spectroscopy, gives the PVA a significant distinction between suspending and emulsifying agents, and uses them in reactors for the production of PVC-suspensions of large dimensions (100-150 m 3). To discover them. The problem of controlling the particle size distribution of the finished PVC-S is well known.

Example 4

In this test, we intend to demonstrate the importance of a method for preparing and premixing different PVA NS, which is the object of the present invention, before removing the solvent.

We want to demonstrate the importance of how NS prepares and premixes different PVAs. Full hot mixing of a methyl alcohol-water analogous solution of polyvinyl alcohol with different NS is, in fact, continuous distillation of methyl alcohol and condensation in the form of regular particulate forms of 0.01 to 10 μm diameter of polyvinyl alcohol which is entirely insoluble in water. Create an environment where things can happen.

To demonstrate this, the inventors have carried out two separate hypoalcohol degradation reactions, and then combined the two materials to continuously carry out the removal and dilution steps of the solvent as described in the claims herein. Decided.

First Step of Example 4

The inventors dropped 200 Kg of a methanol solution containing 50% PVAc-K25 as used in Examples 1,2 and 3 into the reactor, and then stabilized the product at a temperature of 37 ° C. for 5400 seconds (60 minutes). 30 Kg of a 5% sodium methylate solution in methyl alcohol was added dropwise. After a certain time, acetic acid is added to stop the process to pH 6.5, which is diluted with 30 Kg of water.

The solution containing the polyvinyl alcohol of NS 480 is stored separately for subsequent addition to a solution derived from the following divalent alcohol decomposition.

Second Step of Example 4

Into the reactor is placed 200 kg of a methanol solution containing 50% PVAc-K25 of the same type as described in Example 2-3. The temperature is raised to reflux and 1 Kg of H ₂ SO ₄ (g / ml (d)) is further added dropwise. Reflux is continued until the temperature of the material drops 2 ° C. The method is stopped using 0.8 Kg of NaOH solution dissolved in 50 Kg of water. The pH was adjusted to 6.5 and brought to NS rk 230 of polyvinyl alcohol. To this material still heated and stirring, a methanol solution prepared by the first alcohol reaction was added and a homogenization process was carried out for 5400 seconds (60 minutes). Unlike Examples 1, 2 and 3 above, the process of continuous operation of removal and dilution is continued. The properties of the emulsion of the code name PVA-A ₄ and its analysis results demonstrated the identity with the emulsions prepared in Examples 1, 2 and 3 above. The polyvinyl alcohols present in PVA-A4 are those made by two different alcoholic decomposition techniques, and more specifically, PVA BLOCKY consisting of water-soluble PVA RANDOM and water-insoluble fine particles. Theoretically, the percentage of salts derived by two separate hydrolysis in the final emulsion is high in the percentage of ash remaining, which is for example six times higher than in Example 2, more precisely from 0.05 to 0.33%. This increase in salt adversely affects the electrical properties of PVC-S.

Example 5

Good results in the quality of the PVC suspensions prepared using the aqueous emulsions of the PVA of the present invention in combination with the PVA blend according to the RANDOM-BLOCKY mixed gacolysis technique result in the following new examples: in the reactor As in Example 2-3-4, 200 Kg of methanol solution of PVAc-K50 is added. The temperature is stabilized at 35 ° C. for 4 hours and 10 kg methanol solution containing 5% sodium methylate is loaded. Thereafter, ₂₀₀ Kg of the PVAc-K25 solution and 1.5 kg of H ₂ SO ₄ (g / mL (d) 1.83) as in Example 2-3-4 were further added dropwise.

The reaction is refluxed for another 6 hours and the methyl acetate-methanol azeotrope is extracted as previously described in the above examples. The total distillation amount is 120 kg.

The reaction was terminated by adjusting the aqueous NaOH solution to pH 6.5.

As in Examples 1-2-1-2-3-4, the removal and dilution of the solvent were carried out to continue the process. The aqueous emulsion defined by code PVA-A5 is similar to the above embodiments.

The hydroxyl group distribution type is BLOCKY-RANDOM with a water soluble PVA fraction and RANDOM with a water-insoluble polyvinyl alcohol fraction.

All data for Examples 1-2-3-4-5 are shown in Table 1.

Examining Table 1, where the results of the alcoholic decomposition test are presented, it can be seen that different types of polyvinyl alcohol aqueous emulsions with different NS can be obtained:

Depending on the analytical method, polyvinyl acetates from aqueous emulsions, aqueous suspensions, alcohol solutions, and block counterparts are shown with K values ranging from 10 to 110 and varying in molecular weight distribution.

All gacoalcohol decomposition techniques mentioned in the literature as RANDOM-BLOCKY and their possible combinations have been applied.

The process of the present invention provides a highly reproducible and industrially applicable method with economical and environmental considerations for the preparation of novel suspending agents for solving many of the problems in polymerizing vinyl chloride in suspension.

Description of PVC-S Polymerization Examples of Tables 1 and 2

Polymerization tests of vinyl chloride monomers of type PVA-A1-A2-A3-A4-A5 were carried out in a 500-liter autoclave, which had an inner wall formed of stainless steel (AISI 316LC), an impeller in the form of a stirrer, Two brake wave blades located 180 ° opposite each other are anchored to the reactor wall.

The autoclave is equipped with a closed manhole, a spray device for preventing keratinization, and a valve of 1519,9 KPa absv (15ATA) for cleaning the interior with water (Demi). In the head of the reactor, a condenser for reflux having a surface area of 2.5 m 2 may be inserted.

The polymerization reaction has been considered to be achieved when the reaction pressure drops to 354.6 KPa abs (3.5 bar), and the final conversion for each load has been measured by the degassing and recovery of unreacted VCM.

The suspension can be stripped by direct injection of medium air at temperatures below 75 ° C. to 405.3 KPa abs (4ATA), after which the suspension is centrifuged and PVC-S containing 23% moisture is dried in a fluidized bed. I was.

After the treatment, PVC-S was analyzed by the following analysis method as in the above examples; Apparent density: Kg / 1 according to DIN 53-468; Plasticization efficiency in% according to DIN 53-734; Particle size distribution: measured according to DIN 53-784; Volume resistivity: measured according to ASTM D257-66; internal porosity with a pore average diameter in μ: average volume of pores in cc / g; A value measured by a mercury porosity measuring device (porosimeter) of the Carlo Erba Series 200; The residual amount of VCM after PVC-S drying was measured by gas chromatography and expressed in ppm; Gelled Particles-Fish-Eye.

In addition, the following method was used. A premix of 2.4 g of 160 g of PVC-S, 80 g of dioctyl phthalate, 0.8 g of cadmium stearate, and PVC-S-carbon black and cadmium stearate for 300 seconds (5 minutes) Mixed. To calendar at 140 ° C., a 0.0001 m (0.1 mm) thick film was prepared, after 300 seconds (5 minutes), 1 m 2 was taken and the transparency measured to determine the non-pigmented particles (fish) in the film specimens of the product. It is possible to weigh the child).

Thermal Stability: This test was performed in comparison with the specimens of PVC-S for the above-mentioned plasticized PVC-S stabilized and lubricated by standard methods. From the resulting mixture after a calendaring operation at 140 ° C. for 600 seconds (10 minutes), a 0.001 m (1 mm) thick specimen was placed on a 165 ° C. stove. The time, in minutes, was then measured for various rows of fertilizers with previously prepared specimens. The greater the time displayed per minute, the better the thermal stability of the PVC-S for work.

Example 6-7-8-9-10

As a first series of tests, all types of PVC-S known in the industry will be prepared when the PVC-A1-A2-A3-A4-A5 type is formulated without the aid of other first or second suspensions. Prove that you can.

According to the different composition of PVA-A1-A2-A3-A4-A5, as is well known to those skilled in the art, all types of constant quantitative PVC-S that have significant advantages in synergy with non-toxic stabilizers and the like in subsequent conversion steps. Formulations can be used.

In test 6, complete compatibility of mercaptoethanol and PVA-A2, which are usually used as chain transfer agents in the production of low molecular weight PVC-S, was observed. We have demonstrated that other types of chain transfer agents may be used, for example trichloroethylene, dechloroethylene, and if necessary cross-linked diallyl-maleate.

Example 11

Use of PVA-A2 in a test to insert a reflux condenser in an autoclave for polymerization may demonstrate that the quality of the finished PVC-S is not compromised at all compared to other tests performed without the condenser. .

After 20 loads performed with PVA-A2, the reflux condenser was completely purged, demonstrating the antifoaming and emulsifying effect that PVA-A2 provides from the beginning of the synthesis reaction. The productivity increase of the reactor was about 20%.

Example 12

This experiment, conducted using an initial loading of H ₂ O Demi at a temperature of 65-70 ° C., was able to solve one of the major problems associated with loading on the autoclave, ie heating with a reactor outer liner. The start time can be reduced by more than 1800 seconds (30 minutes).

This important loading technique not only significantly reduces the manufacturing cycle, but also avoids the performance of continuous overheating in the reactor liner, which impedes the keratin-preventing effect of special agents applied with various techniques prior to loading.

The advantage of achieving homogeneous and immediate dispersion of non-aqueous PVA particulates from the beginning of the reaction proves to be of extreme industrial value in this case, ie, the usual adverse effect on the quality of the prepared PNC-S. The rise in manufacturing can be achieved without.

Example 13

The analytical tests 6 to 12 were carried out using a pH of 7 at the start of the polymerization reaction and 300 ppm NaHCO 3 as a buffer. The inventors have also found that other types of buffers can be used, for example, ammonium hydroxide, sodium hydroxide, sodium carbonate, magnesium hydroxide, sodium phosphate, for the adjustment of pH values.

Test 13 demonstrates that the quality of PVC-S can be maintained at high levels when the buffer is excluded and the autonomous air 02 at the start of the autoclave loading is several ppm and the pH value is about 3.

Finally used to control the particle size distribution of PVC-S, the control of residual vacuum in the reactor is perfectly applicable to formulations using the PVA type that is the object of the present invention.

Example 14

In test 14 as compared to test 6, PVA type A2 was loaded at exactly 1200 ppm at two different instants of the polymerization, i.e. at the beginning of the polymerization, and 600 hours for 1800 seconds (30 minutes) 1 hour after the start of the polymerization. The case of loading ppm is demonstrated.

The apparent density and thermal stability of PVC-S showed a predicted improvement, and the optimum level of particle size distribution is shown in other properties.

Examples 15 and 16

By using a technique using a homogenizing roller to disperse and / or a technique using evaporation of high vacuum (boiling point; 6 to 8 ° C.) solvents (methyl acetate, ethyl acetate, etc.), the inventors have described PVA of the following catalysts: Type A2 aqueous emulsion was used.

Using the catalyst emulsion prepared as above for PVC-S, the inventors conducted polymerization tests 15 and 16.

From the equilibrium aspects of the polymerization and the results of the analysis of the PVC-S produced, we found that other types of suspending agents or emulsifiers in which PVA is detrimental to certain properties such as, for example, volume resistance, apparent viscosity and particle size distribution of tile PVC-S It has been found to be particularly suitable for preparing aqueous emulsions of catalysts without the need for simultaneous use.

The optimum stability of the aqueous emulsion of the catalyst form abcd, and the final quality of the PVC-S, were obtained by contacting the catalyst microparticles with a diameter of 1 to 8 microns obtained using the techniques described above with other suitable microparticles having the same diameter as the water-insoluble polyvinyl alcohol. And due to the major fractions of water soluble polyvinyl alcohol present in the PVA, it can be caused by emulsification together in water.

In tests c and d, ethyl alcohol acts to lower the freezing point of the emulsion to about -20 ° C.

The presence of the ethyl alcohol of the present invention in an aqueous emulsion is essential to the preparation and distillation of PVA, which is the object of the present invention, and virtually all cited to prepare PVA-A1-A2-A3-A4-A5. Although methyl alcohol was used in the examples, as will be appreciated by those skilled in the art, it is possible to perform all hydrolysis in ethyl alcohol and ultimately leave residual ethyl alcohol as needed for the freezing point required for the emulsion itself.

In all cases, the properties of the final PVC-S are at a high qualitative level. In the prior art, it has already been observed by those skilled in the art, and there is no deterioration (Pejorative) phenomenon inherently caused by the weak dispersion of catalyst particles from the start of the polymerization reaction.

Example 17-18-19-20-21-22-23

These tests are intended to illustrate the important application of the method of the invention to those skilled in the art. Only a limited degree of embodiment will be presented, but this is not intended to limit the various changes and modifications in the application of the invention.

In the experiments of this test group, those skilled in the art will appreciate that PVA-A2 is compatible with all the techniques used in the polymerization of PVC-S and with all known suspending agents.

The morphological characteristics of the finished PVC-S can be identified by optimum levels of quality, in particular particle size distribution values, thermal stability values, internal porosity, and VCM residue levels after PVC-S drying.

During the test, cold PVA can be dispersed in a solution of various first suspending agents and the water can be transported to the automatic loading line and to the reactor itself. PVA fine particles resulted in stable results and did not exhibit sticking or condensation upon contact with any of the suspension solutions or with water that was not completely warmed prior to loading the autoclave.

Cleaning Examples of Autoclaves

Using the formulations described in Example II, we carried out 20 polymerization reactions after each synthesis reaction using different kinds of anti-keratinizers.

In these results, in the case of all the tiles, different keratinization prevention products were used, and the optimum compatibility of the target product of this invention was confirmed. After 20 minutes of polymerization with each type of keratinizing agent, both the inside of the reactor and the reflux condenser are completely clean and no residue remains, requiring a suspension of the test cycle. In order to be advantageous in obtaining good results of the process of the present invention, the inventors present a method of using 0.05 to 8 parts by weight of sulfuric acid and / or sodium methylate and / or sodium hydroxide, respectively, based on PVA.

The alcohol used for the dialcohol decomposition reaction is methyl alcohol or ethyl alcohol, and 0.2 to 20 times, preferably 3 times, based on PVAc.

From the viewpoint of industrial usability and cost, the alcohol used for the decomposition of the alcohol is preferably methyl alcohol, and 0.2 to 20 times, preferably 3 times the amount of PVAc.

It is evident that this proportion of methyl alcohol can replace all or part of ethyl alcohol, depending on the toxical aspect or other uses.

TABLE 1 Summary of Examples 1-2-3-4-5

TABLE 2A Summary of Examples 6-14

TABLE 2B Summary of Examples 15-23

In the table, the (*) value indicates p.p. of the effective catalyst.

Claims (4)

A process for preparing an aqueous emulsion of two or more polyvinyl alcohols (PVAs) having different influencers (NS) for preparing polyvinyl chloride (PVC-S) in an aqueous suspension, i) having a molecular weight of 30 to 110 Using a first polyvinyl acetate (PVAc) of K, the polyvinyl acetate (PVAc) of an acid or base catalyst in the presence of ethyl alcohol or methyl alcohol until the value (NS) of 598 to 135 Performing an alcoholic decomposition; ii) dropping a second polyvinyl acetate (PVAc) having a molecular weight of 10 to 90 K in an amount of 0.1 to 5 times by weight based on the first polyvinyl acetate (PVAc); iii) stopping the polyalcohol decomposition reaction so that each polyvinyl alcohol (PVA) in the final alcohol solution is completely mixed so that (a) a water-soluble first polyvinyl alcohol (PVA) having a value of 280 to 95 ), And (b) obtaining a water-insoluble second polyvinyl alcohol (PVA) having a value (NS) of 598 to 312; And iv) distilling the residual solvent during or after the end of the alcoholic decomposition reaction and adding water after the alcoholic decomposition reaction so that the second polyvinyl alcohol (PVA) has a particle size distribution of 0.01 μm to 10 μm in water. Method of producing a polyvinyl alcohol (PVA) aqueous emulsion, characterized in that it comprises the step of condensation. The method of claim 1, wherein the catalyst is at least one catalyst selected from the group consisting of sulfuric acid, sodium methylate and sodium hydroxide, characterized in that 0.05 to 8 parts by weight, respectively, based on polyvinyl acetate (PVAc) is used. Process for the preparation of polyvinyl alcohol (PVA) aqueous emulsions. The polyvinyl alcohol (PVA) aqueous emulsion according to claim 1, wherein the alcohol used for the decomposition of the alcohol is used in an amount of 0.2 to 20 times by weight based on polyvinyl acetate (PVAc) as methyl alcohol. Way. The polyvinyl alcohol (PVA) aqueous emulsion according to claim 1, wherein the alcohol used for the decomposition of the alcohol is used in an amount of 0.2 to 20 times by weight based on polyvinyl acetate (PVAc) as ethyl alcohol. Way.