KR830000870B1 - Separation and Purification of Ethylene-Vinyl Acetate Copolymer Saponified - Google Patents

Abstract

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Description

Separation and purification of ethylene-vinyl acetate copolymer saponified

The present invention relates to a method for separating and purifying ethylene-vinyl acetate copolymer gums.

It has already been known to carry out saponification of ethylene vinyl acetate copolymer having a vinyl acetate content of 5 to 35% by weight with an alkali or an acid catalyst in the presence of a mixed solvent of an aromatic hydrocarbon solvent and a low boiling alcohol. In addition, various methods have been proposed for recovering the saponified product from the reaction solution after the completion of the saponification reaction.

One method is to add alcohol to the reaction solution as a precipitant and recover the saponified product in fine powder. Another method is to extract catalyst residues and water-soluble impurities, especially sodium acetate, by water, and then dry them to remove the solvent and water, or recover the saponified material by the type of steam in the presence of a suitable surfactant.

However, the method of precipitating and recovering the saponified product by adding the former low boiling alcohol as a precipitant has the disadvantage that the saponified product is largely lost and difficult to handle when the saponified product is separated, cleaned and dried. There was this. In addition, it was found that the amount of the saponification which does not precipitate even when low boiling alcohol is added is large, and the ratio is usually uneconomical because it may affect the number of saponification%.

In addition, since this method requires a large amount of low-boiling alcohol, it was found to be a very disadvantageous method on an industrial scale, considering the recovery and separation of the low-boiling alcohol.

On the other hand, after extracting with water of the latter, a method of recovering the saponification by steam distillation by adding a surfactant, a large number of five to 10 times the extraction operation by adding 5 times the amount of water to the saponification in one extraction operation. There was a drawback that the catalyst residue and water-soluble impurities in the saponified material, in particular, sodium acetate, could not be sufficiently removed if not carried out.

In the case where the solvent is distilled off by steam distillation, since the saponification becomes fused and the extraction from the reaction system becomes difficult, this operation is usually performed by adding a surfactant. By the way, it was found that the added surfactant could not be completely removed, and the remaining surfactant lowered the physical properties of the cargo.

In view of such circumstances, the present inventors earnestly examined, and added to the vinyl acetate copolymer 100 parts by weight of a mixed solvent of an aromatic hydrocarbon and a lower alcohol to obtain a homogeneous solution. After alkali detection by addition of an alkali catalyst, unsaturated carboxylic acid or cyclic anhydride is reacted with this ignition if necessary, and then the reaction solution is subjected to (I) solvent content in the system. Solvent is distilled off until it is 10-100 weight part with respect to 100 weight part of this saponifiers. (Ⅱ) Is 200 parts by weight or more of water added to 100 parts by weight of this saponified material? The temperature of the (III) system is kept above the softening point of this saponified material and emulsified. (IV) By treating the system temperature in the order of lowering the softening point of this saponified product while stirring, the saponified product is obtained in granules having an average particle diameter of about 0.5 to 100 mm, so that it is difficult to handle in a later separation and drying process. It has been found that it is easy and there is little loss when separating the saponification, and also the contents of catalyst residues and water-soluble impurities in the saponification, in particular, sodium acetate are extremely low.

Based on such knowledge, it came to complete this invention.

That is, according to the present invention, ethylene-vinyl acetate copolymer having a vinyl acetate content of about 5 to 35% by weight is added to (1) 150 parts by weight of a mixed solvent of aromatic hydrocarbons and a lower alcohol to 100 parts by weight of the copolymer and alkali saponification.

② If necessary, react this saponified unsaturated carboxylic acid or sulfate anhydride.

③ The solvent is distilled off until the solvent in the system reaches 10 to 100 parts by weight based on 100 parts by weight of this saponifier.

(4) Add 200 parts by weight or more of water to 100 parts by weight of this saponified substance.

⑤ Keep the temperature of the system above the softening point of this sample and emulsify it.

(6) The method of separating and purifying the ethylene-vinyl acetate copolymer saponifier, characterized in that the temperature of the system is lowered than the softening point of this saponifier while stirring.

The ethylene-vinyl acetate copolymer used in the present invention is obtained by copolymerizing ethylene and vinyl acetate by a known method (e.g., U.S. Patent Nos. 2,200,429, 2,703,794, etc.), and the vinyl acetate content is about 5 to 35% by weight. It's%.

In the present invention, first, a mixed solution of an aromatic hydrocarbon and a lower alcohol is added to 100 parts by weight of the ethylene-vinyl acetate to 150 parts by weight or more, preferably 200 to 300 parts by weight to prepare a homogeneous solution of the ethylene-vinyl acetate copolymer. Alkali gum is added to an alkali catalyst.

Examples of aromatic hydrocarbons used in alkali saponification include benzene, toluene, 0-xylene, m-xylene, p-xylene, pseudo cumene, mesitylene, isodurene, pentamethylbenzene and hexamethylbenzene Having a hydrocarbon having one benzene such as ethyl, benzene, cumene or styrene and two or more benzene rings such as biphenyl, p-tertyl, diphenylmethane, triphenylmethane, bibenzyl and stilbene Hydrocarbons; and the like. Moreover, as lower alcohol, methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, sec-butyl alcohol, sert-butyl alcohol etc. are mentioned, for example. The lower alcohol is added mainly to control the saponification degree of the ethylene-vinyl acetate copolymer, but the amount is preferably about 1 / 10-1 / 100 in the weight ratio of the aromatic hydrocarbon and the lower alcohol. Alkali catalysts used in alkali saponification include, for example, alkali metals such as sodium hydroxide, lithium hydroxide, calcium hydroxide, hydroxides of alkaline earth metals such as sodium methoxide, sodium methoxide, potassium methoxide, potassium methoxide, potassium methoxide, magnesium Alcoholates, such as ethoxide and potassium-t- bromide, etc. are mentioned.

The amount of the alkali catalyst is usually about 0.1 to 10 parts by weight based on 100 parts by weight of the ethylene-vinyl acetate copolymer. Alkali saponification of the ethylene-vinyl acetate copolymer varies depending on the degree of saponification, the amount of the alkali catalyst and the like, but is usually performed at a temperature of about 30 to 100 ° C. for about 0.05 to 10 hours. The degree of saponification is usually preferably about 30 to 100%.

Thus, the alkali gum ethylene-vinyl acetate copolymer may react unsaturated carboxylic acid or cyclic anhydride as needed.

When reacting unsaturated carboxylic acid, it is performed by heating the alkali saponified reaction liquid to the temperature mentioned later, after adding a radical forming substance or adding a radical forming substance, and heating to the temperature mentioned later. Herein, unsaturated carboxylic acid means that R and R 'are represented by hydrogen, alkali, carboxyl group or carboxylic acid in the general formula CHR' = CRCOOH, and specifically, for example, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, and the like. Monocarboxylic acid is mentioned. The amount of unsaturated carboxylic acid is at most about 5% by weight, preferably about 0.2 to 3% by weight, relative to this saponified material. Radical-forming substances are those that can readily decompose to form radicals at the graft synthesis temperature, for example, organic peroxides such as benzoyl peroxide, lauroyl peroxide, and dicumyl peroxide, and α, α ' -Nitrogenous compounds such as azobisisobutyronitrile and the like. These radical forming materials are used in amounts of about 0.05 to 3% by weight, preferably about 0.1 to 1% by weight, based on the saponified material. The heating temperature cannot be uniformly determined by the type of unsaturated carboxylic acid or solvent used, but the heating temperature is about 50 to 150 ° C. and the heating time is about 0.1 to 5 hours.

로 표시되는 것으로, R은 예컨대 2가(價)의 방향족 또는 지방족 잔기를 나타낸다. 구체적으로는 예컨대 무수마레인산, 무수호박산, 무수글루타르산, 무수프탈산, 무수이타콘산, 무수트리멜리트산, 무수하이미크산 등을 들 수 있다. 상기의 반응에서 환상산무수물은 감화물중에 함유되는 OH가에 의해서 개환(開環)하여

로 되어 있는 것으로 추정된다. 환상산무수물의 양은 이 감화물중에 함유되는 비닐알콜 단위중, 많아야 약 5몰%, 바람직하게는 약0.2~2몰%를 반응시키는(에스테르화하는)데 필요한 양이다.When the cyclic acid anhydride is allowed to react with the saponified compound, the cyclic acid anhydride is added to the alkali saponified reaction solution and heated by about 50 to 150 ° C. for about 0.1 to 5 hours. General formula of cyclic anhydride used here

R is represented by, for example, a divalent aromatic or aliphatic residue. Specifically, for example, maleic anhydride, succinic anhydride, glutaric anhydride, phthalic anhydride, itaconic anhydride, trimellitic anhydride, hymic anhydride, and the like can be given. In the above reaction, the cyclic anhydride is ring-opened by the OH number contained in the saponified material.

It is assumed to be. The amount of the cyclic anhydride is an amount required to react (esterify) at most about 5 mol%, preferably about 0.2 to 2 mol%, of the vinyl alcohol units contained in this saponified material.

By reacting unsaturated carboxylic acid or cyclic anhydride with the saponified product of ethylene-vinyl acetate copolymer, binding properties such as adhesion, water resistance and transparency of the saponified compound are further improved.

Next, in the present invention, the solvent is distilled off until the solvent content in the alkali saponified reaction solution becomes 10 to 100 parts by weight, preferably 20 to 80 parts by weight, based on 100 parts by weight of the saponified material. Although this operation differs depending on the type and ratio of aromatic hydrocarbons and lower alcohols used in alkali saponification, the operation is usually performed at about 80 to 150 ° C. under normal pressure, but may be performed under reduced pressure if necessary. The solvent content in the system can be investigated by, for example, a method of sampling the reaction solution, measuring the weight after leaving it in a dryer at about 170 ° C. for about 1 hour, and calculating the solid content.

One of the characteristics of the present invention is to distill the solvent until the solvent content in the alkali saponified reaction solution becomes 10 to 100 parts by weight based on 100 parts by weight of the saponification agent, but if the residual solvent exceeds 100 parts by weight. Even after the post-treatment according to the present invention, it is not possible to remove the catalyst residue or water-soluble impurity, in particular, sodium acetate, to the extent that it is already industrially available in the sample.

On the other hand, in the case of 10 parts by weight or less, even after the treatment according to the present invention, it is not possible to obtain granular saponification having an average particle diameter of about 0.5 to 10 mm.

Thus, the solvent is distilled off until the solvent content in the system is 10 to 100 parts by weight based on 100 parts by weight of the saponification, and 200 parts by weight or more of water to 100 parts by weight of the saponification, preferably 300 to 600 Add part by weight. As for the temperature which adds water, about 70-95 degreeC is preferable normally. The temperature of the water to be added may be any temperature as long as it is from room temperature to 95 ° C.

Another aspect of the present invention is to add water to 200 parts by weight or more based on 100 parts by weight of the saponification, but when the amount of water is less than 200 parts by weight, even if the post-treatment according to the present invention to obtain granular saponification It is difficult.

Next, in the present invention, the temperature of the system is maintained above the softening point of the saponified material and emulsified.

The softening point of this saponified product is about 50 to 100 ° C., depending on the content of vinyl acetate and the degree of saponification in the ethylene-vinyl acetate copolymer. In particular, the thing of about 70-95 degreeC is preferable. It is preferable to carry out under stirring as much as possible when emulsifying the system.

Another feature of the present invention is to maintain and emulsify the temperature of the system above the softening point of the saponification, but when the temperature of the system is below the softening point of the saponification, the saponification does not emulsify at all. Water-soluble impurities such as catalyst residue and sodium acetate can hardly be removed.

Next, in this invention, the temperature is made lower than the softening point of this saponification while stirring the emulsified system. This operation is preferably performed under fresh agitation, and particularly preferably agitation at a speed of 100 m / sec or more.

Another feature of the present invention is that the temperature of the system is lower than the softening point of the saponification while stirring after maintaining the temperature of one step above the softening point of the saponification and then emulsifying. The saponified product of the granular ethylene-vinyl acetate copolymer of 0.5-10 mm is obtained.

The saponified product of the granular ethylene-vinyl acetate copolymer thus obtained can be separated by a known means such as filtration or centrifugation.

According to the present invention, although the average particle diameter of the obtained saponification is about 0.5 to 10 mm, the water-soluble impurities such as catalyst residues and sodium acetate in the saponification are at a level that enables industrial use of the saponification. To be removed. Moreover, since the average particle diameter of the saponification obtained by this invention is large, it rarely loses saponification during operation | movement of a later separation or drying.

Next, an Example and a comparative example are given and this invention is demonstrated concretely.

In addition, the part and% in an Example and a comparative example represent a weight part or weight%, respectively, unless there is particular notice.

Example 1

A 5-liter four-necked glass flask equipped with a stirrer, a condenser, a thermometer and a nitrogen introduction tube was completely replaced with nitrogen gas. Into this flask, 1978 parts of industrial xylene and 1,150 parts of ethylene-vinyl acetate copolymer (28% by weight of vinyl acetate, density 0.95, and melt index) were heated to 60 to 70 ° C to obtain a homogeneous solution. . Internal temperature was lowered to 60 degreeC, 479 parts of industrial methanol were added, and internal temperature was maintained at 45-50 degreeC again. 67.4 parts of 24% sodium methoxide ethanol solution were added and reacted for 60 minutes at 45-50 degreeC under stirring, Then, 16.2 parts of water was added and the reaction was stopped.

By raising the inner temperature rolling to remove the condenser, and blowing N ₂ gas to 130 ℃ was distilled off to 2339 parts of solvent.

The solvent content in the system was 30 parts with respect to 100 parts by weight of the saponified material, and gas chromatography confirmed that all were xylene. The viscous material was transferred to a 20 L Henschel mixer equipped with a condenser, an N ₂ inlet tube, and a thermometer under pressure of N ₂ gas, and 5,040 parts of water was added thereto, followed by heating under stirring at a rotational speed of 510 rpm. The internal temperature rate was 90 degreeC. The system was then emulsified by stirring for 30 minutes.

Water was added to the jacket of the Henschel mixer, and the system was cooled under stirring at 510 rmp to obtain a granular material having an average particle diameter of 2 mm. The filtrate was separated by gold mesh to obtain 80% by weight of the moistened saponified product as a dry base. This was dried under vacuum at 50 ° C. for 3 hours, whereby an ethylene-vinyl acetate copolymer gum compound having the following physical properties was obtained.

Kendo 91.0% Volatile 0.3%

Melt Index (g / 10min) 175 Average Particle Size 2.5

Oxygen acetate 0.15%

[Examples 2 to 6 and Remarks Example 1 and 2]

2,709 parts of industrial xylenes and 1,260 parts of ethylene-vinyl acetate copolymerization (28% by weight of vinyl acetate acetate, density 0,0.95, melt index 150g / 10min) were placed in 5 L of Prasco equipped with the same equipment as in Example 1. It heated to 70 degreeC and made it the homogeneous solution. Internal temperature was lowered to 16 degreeC, 131 parts of industrial methanol were added, and internal temperature was maintained at 45-50 degreeC. 37 parts of 24% sodium methoxide ethanol solution was added and reacted for 60 minutes at 45-50 degreeC under stirring, 8.8 parts of water were added, stirring was continued for 30 minutes, and reaction was stopped. The internal temperature was then raised under N ₂ gas stream and raised to 120 ° C. while maintaining a low boiling point solvent. After maintaining internal temperature at 120 degreeC, 13.9 parts of acrylic acid and 1.3 parts of benzoyl peroxide were added, and it stirred for 30 minutes. Then the inner temperature was raised to 130 ℃ under N ₂ gas flow, and finally was distilled off the solvent to an amount shown in Table 1.

These viscosities were transferred to a 20 L Henschel mixer as in Example 1 under the pressure of N _2, the internal temperature was lowered to 100 ° C., 7,000 parts of hot water heated to 80 ° C. were added, and the mixture was heated under stirring at a rotational speed of 510 rpm, and the internal temperature was increased to 90 ° C. The system was emulsified by raising the mixture for 30 minutes.

Cooling the emulsion under stirring at 510 m while adding water to the jacket of the Henschel mixer, granules having the average particle diameters shown in Table 1 were obtained, and again dried to give granular ethylene-vinyl acetate in the air with the physical properties shown in Table 1. Coalescing saponification is obtained.

TABLE 1

* 1) It is expressed in parts by weight based on 100 parts of saponified material.

* 2) Confirmed by xylene by dry base and gas chromatography analysis

* 3) Theoretical by-product sodium acetate

* 4) It measured by the RO-Tap method by the JIS standard body.

Example 7

2,150 parts of industrial xylene and 1,000 parts of ethylene vinyl acetate copolymer (28% by weight of vinyl acetate, density 0.95, melt intex 130g / 10min) were put into 5 L of Prasco equipped with the same equipment as in Example 1 It heated and it was set as the uniform solution. The internal temperature was lowered to 60 DEG C, 372 parts of industrial methanol was added, and then 58.8 parts of 25% sodium methoxide-methanol solution was added and reacted at 45-50 DEG C under stirring for 600 minutes, and then 23.5 parts of water was added to stop the reaction. After raising internal temperature to 120 degreeC and distilling a low boiling point solvent, 6.6 parts of maleic anhydride were added, and it was made to react at 120 Pa for 30 minutes. Subsequently, the solvent was distilled off while blowing in N ₂ gas at an internal temperature of 120 ° C., and the solvent content in the system was 40 parts with respect to 100 parts by weight of the saponified material.

After reducing the point plaiting to move in a Henschel mixer internal temperature of 100 ℃ of 20ℓ as in Example 1 under pressure of N _2, it was added a hot 6,000 heated to 80 ℃ portion by heating with stirring in the number of revolutions of 510rpm, with an internal temperature of 90 ℃ The system was emulsified by stirring for 30 minutes.

This emulsion was obtained in the same manner as in Example 1 to obtain an ethylene-vinyl acetate copolymer gum having the following physical properties.

Safflower degree 90.5% sodium acetate 0.3%

Melt index (g / 10min) 65 volatilized 0.2%

Maleic acid esterification (mol% / OH group) 1.8% Average particle size (mm) 1.1

Claims (1)

As described above in the main text, an ethylene-vinyl acetate copolymer having a vinyl acetate content of about 5 to 35% by weight is added to 100 parts by weight of an alkali gum by adding 150 parts by weight or more of a mixed solvent of aromatic hydrocarbon and a lower alcohol, If necessary, unsaturated carboxylic acid or cyclic anhydride is reacted with the saponified compound, and the solvent is distilled off until the solvent content in the system is 10 to 100 parts by weight based on 100 parts by weight of the saponified substance, and 100 parts by weight of the saponified substance. 200 parts by weight or more of water is added, and the temperature of the system is maintained above the softening point of the saponified product, and emulsified. When the mixture is stirred, the temperature of the system is treated in the order of lowering the softening point of the saponified product. Separation and Purification Method of Vinyl Copolymer Gum