DE1770192A1 - Process for the production of completely or partially saponified polyvinyl acetates or vinyl acetate-ethylene copolymers - Google Patents

Description

DR. E. WfEGANP DIPL-INQ. W. NIEMANN 17 7 Q 1

April 11, 1988

PHONE. 555476. 8000 MUNICH 15, »wwv

TELEGRAMMSi KARPATEMT NUSSBAUMSTRASSE 10

V 13641/66 "

Kurashiki Rayon Sau, Ltd. larashiki Gity, Japan

Proceed "s" for production tor Töllig desolate saponified PolyTiiiyiaeeta-teioder

Invention fcflrifft ®ia Tesfaiirea but production το * yereeiiten HoflopoXyatrvK äes? Iayl & e © t tst »öaer Oopoly ^ * Heren Tem Ithylem w && TinyXaottat *

- Inebei ©] sd «re fet the invention meets € * 1κ new«? Experience iur production rom ireyeeifttm SolyTisylaostat © the «soap? I» ylaeetat-li> hyl «». <> - Oc »poXy» er @ K _t -I ^ tti.cfet aekr air 30 MoI-J * Itfeylea contains, whereby Yiiiylacetat or a Geaiech of vinyl acetate tmd Ithylea in an organic solution "ittöl duroh dac Terfakreiäer Ijaeimgspolymerisatioa poly"#riei"rt is formed, a @ re from the ergazd-

dea-niefet "iaBgeaet * t9E

and that Poly * sr® is saponified Polyrinyl alcohol or Teraene Yinylaoetat-Ethylen-Copoiy »ere are usually made by saponifying horn © * · polymepea or Oöpolyiaeren de "get vinyl acetate" if

109839/1705

unreacted vinyl acetate in the reaction mixture of the polymerization remains, the saponified polymer becomes undesirable White discolored »

In order to avoid such errors, it is advantageous to carry out the conversion of the vinyl acetate from the polymerization conversion to almost 100% and a. to use such a polymeric product as a starting material in the saponification reaction.However, such complete polymerization requires an extremely long period of time and is nevertheless ineffective, since the reaction rate drops at the conversion of vinyl acetate and becomes a very small value when the conversion is close to 100 $ .

Therefore, the replacement of the monomer in the reaction mixture was also considered suggested by a solvent before the completion of the polymerization, for example in the following Kind is carried out} A non-reacted monomers8 containing Polyvinyl acetate solution is continuously poured into the top introduced a rectifying Sfyp column, during the Vapor of an alcohol introduced into the column from the bottom becomes · Dadureh becomes an alcoholic at the top of the column Solution of vinyl acetate is obtained and an alcoholic solution of polyvinyl acetate is obtained from the bottom, that is to say Vinyl acetate is replaced by the alcohol, but if methanol or ethanol is used as the alcohol in the above process, the vinyl acetate replaced thereby contains very little Amounts of aldehydes and acetic acid esters that result from the

109839/1705

This alcohol stems from the substance «With repeated circulation This leads to a collection of vinyl acetate of the impurities it contains, causing in turn, the conversion of the material to polyvinyl acetate is reduced and also a discoloration of the polymers formed caused.

For the above reasons, "β is understandable" that at the production of polyvinyl acetate or vinyl acetate-xthylene- · Copolymers if the conversion remains incomplete and Vinyl acetate that was not converted was recovered from the heat exchange is, the Vimylacetataonoiiere carefully isolated and need to be cleaned before it is returned to the cycle will.

For the separation and purification of the Yisylaeetataonoaeren a simple distillation lansmreieheAOa since ₉ if a lower alcohol »like methanol Mgs? Xt & aaoX- ale org & aiss & es Xeussgemittel in the production of the ^ ol ^ vinjlaeetat® © lör ites Tiaylaoetatithylea-CopolyÄeren Tevwendet is the alcohol ©! an aseotropic Sesiiscii * it Viaylacet ^ t- forms ·. In * die sea lall vriLzd-die Ab «| treimwßg ds * Viaylaoitat «* via dea-'Alkotaul duxasls. ^ ia® Extmktlonsdestillation under Tevweadia »e V0Ä.W * s8ar ala Ab-breeaBättel er * - reicht · J * 4o« h maB dag aia £ at®m & Ifeiee used Tlnylaoetat will continue to be 'distilled' into 'the contained verua. «R« iai, f8üsg * n _s wi * Aieekyde «l # ti *, Tl« ®äm ! «Äiyiaeetftt weä. dergl · »ue» .tferewn · Siaa devwr ^^ e 3actrcktioaa | deetillAtloa siad a «asu« ^ eätsliflUe distillation, er ^ erdera jedoeta. eiaan bet ^ äshtliohen apparatus expenditure and ssait üiekoaten and are therefore for the

1O9S30 / 1 70S

BATH ORIGINAL

industrial! technology not justifiable

The above objects are effectively achieved by the present invention. The object of the invention is therefore an economically advantageous process for the production of a colorless saponified high homopolymer Yinylacetate or a copolymer of vinyl acetate and ethylene, thereby preventing loss of vinyl acetate and fully completing the vinyl acetate refining processes listed above can be omitted and the required amount of heat is further reduced

Other objects of the invention will become apparent from the description below.

The above objects and advantages of the invention are achieved by a method wherein vinyl acetate alone or together with ethylene in an organic solvent in the presence of a to form polyvinyl acetate or vinyl acetate-ethylene copolymer with a content of not more than 80 MoI-Ji Ethylene suitable polymerization catalyst are polymerized, the organic solvent is evaporated by heating the reaction mixture e, to the polymer obtained a lower aliphatic saturated alcohol is added and the product saponified in the presence of an alkali catalyst is formed, a fully or partially saponified polyvinyl acetate or vinyl acetate-ethylene copolymer is formed and iat characterized in that the polymerization in tert »- Butanol is carried out as an organic solvent »until

109839 / 170S

The conversion of vinyl acetate into polymer 15 to 90% by weight reached and that neutral or basic "KupferwII" acetate dem su heating reaction mixture is added and that tert »- Butanol and the monomeric vinyl acetate evaporated and recovered

will"

The method according to the invention is then carried out in a its on the basis of the order of the β in its stages in comparison the usual procedures are further explained below »

1 «) Production of polyvinyl acetate or of vinyl acetate- ethylene copolymers ι

Polymerization of vinyl acetate alone or with ethylene in solution in an organic solvent such as methanol in the presence of a polymerization catalyst is known. Suitable catalysts are the following _ζ β Β · ale useful bekanntt nitrogen compounds, the free Radikal® upon thermal decomposition form, such as "B" o ^ ft'-azo-isobutyronitrile, ata ^ -AsobisCa ^ y-dimethyl valeronitrile), "a Azo ^ diisobutyric acid, dinitrile and similar and organic: peroxides, such as Bansoy peroxide or lauroyl peroxide

According to the invention, for the production of polyvinyl acetate or vinyl acetate-ethylene copolymers that are no more than 80 mol ~ # contain ethylene and the following course as vinyl « Ac «tat-ethylene copolymers are designated ^ by polymerization of vinyl acetate alone or together with ethylene in one organic solvent in the presence of one of the above "known catalysts tert" -Buta & ol ala organic solution-

109839/1705

Used means and the Polymerieationsreaktion is terminated when the conversion of vinyl acetate in the polymers' 15 to 90 wt _e - # has reached ·

The polymerization can according to the invention, for example by. A polymerization vessel can be charged with tert-butanol and one of the above catalysts, a certain amount of vinyl acetate added and the system heated to 40 to 60 ^° C., normally at atmospheric pressure. If desired, an increased pressure can also be used. For the copolymerization of vinyl acetate with ethylene, a certain amount of ethylene is added to the above polymerization system from vinyl acetate according to the desired copolymerization ratio, the ethylene pressure being set in a suitable manner. The copolymerization ratio is determined by factors such as polymerization temperature, ethylene pressure and the quantitative ratios between vinyl acetate and Ethylene is determined in the system. The specific conditions can easily be determined by experiments

The lower limit of the ratio of tert »-butanol, which is the solvent, to vinyl acetate is made by the minimum amount of solvent necessary for a smooth The course of the polymerization is determined, the formation of crosslinked polymers being prevented or reduced, furthermore by the increase in viscosity of the reaction mixture and difficulties in removing the heat of polymerization which can be caused by high viscosity Furthermore, the upper limit is determined by economic considerations

109839/1705

determined, ie ₀ that point * above which the volume efficiency of the polyaerization vessel is unsuitable for use in practice. The preferred ratio of tert-butanol to monomeric vinyl acetate in the practice of the invention is between 0.1 and 7% by weight.

In the usual processes, in the majority of cases, methanol is used as the organic solvent for the polymerization of Vinyl acetate used in the industrial mafia "because it is very cheap" ■

* f

and methanol solutions of polyvinyl acetate are low viscosities have what makes them convenient for transport. However, it has been found that methanol is a solvent Number of disadvantages and that the use of tert-butanol Gives surprisingly beneficial results.

2 «) Separation of the vinyl acetate monomer and the organic solvent from the polymer formed:

According to the invention, the reaction mixture obtained in the above polymerization is then heated, so that tert-butanol and unreacted vinyl acetate evaporate " and these are obtained by condensation, making them of the polyvinyl acetate or vinyl acetate-ethylene copolymers, the were formed during the previous polymerization, are separated «,

You can heat the polymerisation mixture in a higher temperature than the boiling point of the vinyl acetate below

109839/1705

the operating pressure, but lower than 150 ⁰ C can be carried out. Furthermore, the heating can be carried out under atmospheric pressure or under reduced pressure, heating can be carried out at any temperature where terto-butanol and vinyl acetate evaporate effectively and no significant conversion between vinyl acetate and tert-butanol took place

Any vessel commonly used for the treatment of high / viscous substances can be used as a container in this heating will. For example, a thin-film evaporator or a device with spinning or scraping devices used to concentrate highly / viscous materials

As discussed above, the reaction mixture still contains considerable amounts of monomeric vinyl acetate. According to the invention, neutral copper (II) acetate / Cu (CH ₅ COO) ₂ / or basic copper (II) acetate / Cu (CH ₅ COO) ₂ CuQ / is added to the reaction mixture before heating in an amount of 1 10 to 5 χ 10? G preferably 1 χ *** 10 to 5 x 10 96, the weight thereof added "In this way is during the subsequent heating of the mixture to evaporate and to obtain dee mono mers of vinyl acetate and tert" -Butanole polymerization effectively prevented by vinyl acetate and, furthermore, there is no reaction between vinyl acetate and tert-butanol in the presence of the copper salt listed above. Therefore, the adverse formation of aldehydes and EeeigeÄureeatern as by-products is effectively prevented. During the subsequent saponification

109839/1705

the polyvinyl acetate or vinyl acetate-ethylene copolymers separated in this way result in pure white products that do not have any undesirable coloring. Liquid mixture obtained from monomeric vinyl acetate and tert " Butane oil is practically free of any by-products and can be used in the polymerisation system can be returned to the circuit without cleaning in between

3 «) saponification of polyvinyl acetate or vinyl acetate

Ethylene Copolyae r s

According to the invention, the polyvinyl acetate or vinyl acetate-ethylene gopolymer separated off in the above% stage is converted into a homogeneous solution or suspension in which the polymer is uniformly dispersed by adding thereto

at least an equimolar amount, preferably at least 2 hol per mole

/ existing in the polymer, acetic acid residues of an aliphatic saturated alcohol having from 1 to 4 carbon atoms and if necessary still other organic solvents in accordance with conventional practice, eye give wirdβ To the solution the required amount of alkali is then added to saponify completely or partly around the ä polymers or copolymers and the saponified product is recovered in the usual manner. The specific nature of the alcohol to be added to the reaction mixture is essentially not critical as far as it is capable of carrying out the saponification reaction of the polymer. Normally, aliphatic saturated alcohols with 1 to 4 carbon «

109839/17 05

atoms are used because of their easy accessibility and handling and low cost. The amount of alcohol is by no means critical insofar as it allows easy recovery of the saponified product

As an organic solvent that is advantageously added, e.g. aromatic organic solvents such as benzene, Toluene and the like can be used. Simultaneous use such an organic solvent together with the alcohol is used to improve the solubility of vinyl acetate-ethylene copolymers valuable. For example, copolymers containing no more than 61 moles of copolymerized ethylene are soluble in methanol, while copolymers with a higher ethylene content are only partially soluble or insoluble in methanol are. In the latter case, it is preferred to use an aromatic organic solvent such as benzene or toluene, the methanol add to improve the solubility of the copolymer »

Suitable alkali for the saponification reaction Bind Z ₀ B, alkali hydroxides such as caustic soda or caustic potassium, lower alcoholates of alkali metals such as sodium methylate or ethylate and the like Copolymer ization ratio of vinyl acetate to ethylene and selected derglo. Generally speaking, larger amounts of alkali are required for saponifying vinyl acetate-ethylene copolymers than for saponifying polyvinyl acetate. The preferred temperature for saponification is in the range from room temperature to

109839/1705

That by, the above saponification in whole or in part saponified polyvinyl acetate or vinyl acetate-ethylene copolymers can fall out of the reaction liquid or remain dissolved or partially fail and partially dissolved in the liquid remain of such factors as the degree of saponification of the Products », copolymerization ratio of vinyl acetate to ethylene and the like, depends«

If the total amount of the saponified product fails, this can be separated off by known filtration processes. If all or part of the product in the year Reaction liquid remains dissolved, another becomes suitable Non-solvent added to the system to cause the saponified product to precipitate. The precipitation can be obtained by filtration. The product obtained in the process can furthermore be freed from liquid components if necessary, it is dried and as an end product according to of the invention used. The saponified product can be recovered by any known means will,

As already stated above, the characteristic Features of the invention in the use of tert-butanol as an organic solvent in the polymerization of vinyl acetate or the copolymerization of vinyl acetate with Ethylene, in which the polymerization reaction ceases at a point in time when 15 to 90% by weight of that is present in the system Vinyl acetate are converted into polymer or copolymer and

109833/17 05

in the recovery process for tert-butanol and unreacted Vinyl acetate from the reaction mixture obtained, a neutral or basic copper (II) acetate being added to the reaction mixture is added and the system is heated so that tert-butanol and non-reacted vinyl acetate evaporate and to be won <>

Heretofore, those skilled in the art have attempted evaporation for the purpose of recovering the unreacted vinyl acetate and the organic Solvent with heating in the polymerization of vinyl acetate or the copolymerization of vinyl acetate with Ethylene in an organic solvent in the presence of a catalyst reaction mixture obtained a polymerization retarding adding an acting agent or a polymerization inhibitor to the reaction mixture before heating to effect polymerization of vinyl acetate during heating.

However, most of the usual polymerization inhibitors show a tendency to discolour the saponified products from polyvinyl acetate and vinyl acetate! ethylene copolyaeren while their saponification.

As a result of numerous attempts at polymerization inhibitors was found in the context of the invention that when using neutral or basic »copper (II) acetate a far less discoloration turns out and a far greater polymerization-inhibiting effect occurs than bti others common polymerisation skin materials »

However, both neutral »copper (II) acetate also show basic copper (II) acetate the fault that it does the implementation voa

109 839/1706

Aonomeric vinyl acetate with a lower alcohol, such as methanol, ethanol, n-propanol, iso-propanol, n-butanol and sec-butanol strongly favor and as a result the formation of acetic acid esters or aldehydes is increased. Therefore, the use of neutral or basic copper IX acetate as a polymerisation inhibitor cannot be applied to the polymerization systems where polyvinyl acetate or a vinyl acetate-ethylene copolymer are prepared using these lower alcohols as solvents, although neutral or basic M cupric acetate provide such advantages in terms of discoloration ©

It has been found in the present invention that Terto-butanol has the special property that it can not react with vinyl acetate at temperatures below 15O ⁰ C, even if neutral or basic cupric acetate are present.

It was therefore found within the scope of the invention that if tert-butanol specifically as an organic solvent the polymerization is used and neutral or basic Copper (II) acetate are used as a polymerization inhibitor, the following advantages arise:

1 ·) The polymerization of vinyl acetate is practically inhibited during the heating stage j
2.) the reaction between terto-butanol and vinyl acetate can

very effectively prevented j
3 ·) the aurüekigew'onnöxiö '? Lü30igköitsg9a ± sch from and vinyl acetate "can be repeated zn the

109839/1705

BATH ORIGINAL

step without a “wiped-off cleaning step” will;

4o) the possibility of omitting the intermediate cleaning stage are significant advantages for reducing the heat demand, and

5 ·) colorless or practically colorless saponified products can be obtained by the above-described saponification will.

₉ 1 shows that the reaction of vinyl acetate with alcohols having 1 to 4 carbon atoms other than terto-butanol, for example methanol, proceeds well in the presence of copper (II) acetate, while the reaction takes place only slightly if the catalyst is absent . In Fig. 2, the abscissa is the reaction time and the ordinate is the methyl acetate concentration formed in the reaction liquid. Curves A and B show the relationship between the amounts of methyl acetate formed and the reaction time, when 0.1 ° or i «0.001 Gewo- # Cu (CH ₅ COO) ₂ OH ₂ O are added to the system. In both cases A and B the molar ratio of methanol to vinyl acetate 1 and the reaction tempera door 55 ⁰ Co was

In contrast to the results shown in fig. 1, there is no reaction between tert-butanol and vinyl acetate below 150 <£ sbafefc, even if neutral or basic copper (II) acetate is present *

The-according to the invention is based on the above feafcstellimgen hinairjhtlicn te;. · ■ !; > -But & nol and vinyl acetate and lets sieve, therefore ni ^ hfc aiii 'η laarider3 alcohols from 1 to 4

U.38J3 / r'ü ->

Use carbon atoms except tert> -butanol »

An embodiment of the method according to the invention is explained below in connection with the designation of FIG. 2. Vinyl acetate and tert-butanol are fed to the polymerization vessel 1 through line 12, line 5 serves to supply ethylene, which takes place in the case of the copolymerization of vinyl acetate with ethylene. The polymerization will carried out under the conditions already described and the liquid reaction mixture the Äthylendesortiergerät 2 by the lines 13 and 7 supplied, with 7 copper acetate in the line for this purpose, for example, as a solution of the copper (II) acetate in tert-butanol is added. In the case of copolymerization of vinyl acetate and ethylene is practically all of the ethylene in the vessel 2 by measures such as reducing the pressure, desorbed and the remaining liquid is fed to the separating device 3 through the line 8. The separating device consists, for example, of a thin-film evaporator or a device suitable for concentrating highly viscous substances «*, for example a reaction vessel with Seb / db facilities on the wall · The separated in the device 3 " Polymers or copolymers are withdrawn through line 10. The unreacted vinyl acetate and tert-butanol that too were separated in the device 3, the condenser 4 fed through the Hohr 9 and the condensed solution returned through the pipe 11 without an intermittent cleaning stage. Furthermore, the withdrawn polymer or copolymer is fed to the saponification vessel 14 and poured into methanol.

109838 / 17QS

solves, which is supplied from the line 15. The r-soaped polymer or formed in the presence of an alkali catalyst Copolymers is sucked off through line 16

In this way, according to the invention, polyvinyl acetate is obtained or a vinyl acetate-ethylene copolymer that is no more than Contains 80 moles of ethylene, rereduced to any desired level, and the product is free from discoloration and is obtained with economic advantages. Products that have been completely or partially saponified have a wide range of applications, as starting materials for fibers, foils and others shaped products, as paint bases and the like

Since the saponified products of the copolymer, in particular, have no higher content than 80% of ethylene, only a small amount Have oxygen permeability, they are used as a starting material for oxygen shielding of packaged products, for example valuable as packaging films for foodstuffs and the like.

Examples 1, 2 and Comparative Experiments 1 to 9

In these examples, the rewarded polymer! Sation-inhibiting effect of neutral or basic copper (II) acetate is used in comparison with other known inhibitors described and shows that the inhibitor used according to the invention the extent the discoloration of saponified polyvinyl acetate or ethylene-vinyl acetate copolymers even naoh thermal treatments goose considerably reduced

A mixture of vinyl acetate and tert-butanol, the weight ratio of tert-butanol to vinyl acetate being O _t 65

109839/1705

was fed to a polymerization vessel and continuously

ty

copolymerized with ethylene at an ethylene pressure of 36 kg / cm above normal pressure at 6O ⁰ C in the presence of azobisisobutyronitrile as a catalyst. Parts of the ethylene-vinyl acetate copolymer, 54 parts by weight of tert-butanol and 40 parts by weight of unreacted vinyl acetate «For this reaction mixture, each of the polymerization substances listed in Table 1 was added in an amount of 5 x 10% by weight ^ of the vinyl acetate was added and each mixture obtained was fed to the polymer separation device. At 110 ^° C. and 600 mm Hg, unreacted vinyl acetate and tert-butanol were removed and the copolymer was continuously withdrawn. The ethylene content of the copolymer was 35 mol in all cases. The copolymer was dissolved in methanol in such an amount that the concentration was 22% by weight u of the polymer solution in an amount such that the molar ratio of caustic soda to the information contained in the copolymer acetyl groups was 0.3 J, the hydrolysis was carried out at a temperature of 60 ⁰ C for 2 _f 5 hours. The saponified product obtained showed a high degree of saponification of 98.5 mol.

The saponified polymers obtained in this way were formed into pellets by conventional melt extrusion and their discoloration the Stimuluevert Z determines which one is determined by the surface color was measured by means of a reflection method and accordingly

109839/1705

JIS Z8701 is specified. The evaluation of the extent of discoloration is given in Table II.

The polymer pellets were formed into sheets 60 cm wide by a melt extruder with a T-shaped die, and the number of "fish eyes" in each sheet was counted. The values are shown as evaluation numbers in Table III. The number of ^N fish eyes ^N has the following meaning.

Since in the stage of the separation of the unreacted monomeric Vinylacetatβ and dee terto-butanol, the ethylene already are desorbed and removed ... if the polymerization inhibitor of the added inhibitor is low »homopolymers and homooligomers of vinyl acetate are formed and mixed with the ethylene-vinyl acetate copolymer. When the saponified polymer mixture formed is then formed into a film, both saponified ethylene-vinyl acetate copolymer ale also saponified Vinyl acetate homopolymer present in the film. There the two Polymers have only a low compatibility, the film develops "fish eyes". As a result, the number denotes "Fish eyes" in a slide indicate the degree of effectiveness of one used polymerization inhibitor

109839/1705

Table I.

Extent of the inhibiting effects against discoloration and polymerisation of polymerisation inhibitors

attempt

Polymerization inhibitor Degree of discoloration of pellets

Evaluation of the fish eyes in the slide

Example 1 neutral copper (II) acetate Example 2 basic copper (II) acetate, comparison 1 copper naphthenate "2 copper (II) chloride ⁿ 3 copper resinate" 4 copper (II) sulfate (anhydrous) "5 copper (II) iitrate

6 copper I acetate

7 hydroquinone

8 thiodiphenylamine

9 thiourea

I. I. I. I. IV III IV I. IV III IV III IV I. I. V V IV V IV III IV

Table II

Index number of the degree of discoloration Stimulus value Z

II

III

IV

45 5 Z χ · 100 35 « Z χ 45 25 » Z < 35 15 - Z < 25th O » Z < 15th

109839/1705

^x The stimulus value Z was through. Determination of the surface color of sample pellets with a thickness of 8 to 10 mm according to a reflection method according to JIS Z8701 *

Table III

Evaluation of the fish eyes in the slide

Number of fish eyes within 100 cm 'of the foil

II

III

IV

less than 15 15 - 80 80 - 150

150-300

more than 300

Aue from the values in Table I shows that the invention neutral and basic copper (II) acetates used as polymerization inhibitors have a far greater inhibiting effect than show other inhibitors and that at the same time the saponified copolymers obtainable according to the invention are practically free from discoloration are. Although it also shows the monovalent copper (I) acetate, which is not a polymerization inhibitor according to the invention, but has good results in terms of discoloration an extremely poor effect of inhibiting polymerization, so that it is unsatisfactory for practical use is"

Example 3 and comparison tests 10 to 13

To equimolar mixtures of different lower aliphatic Alcohols with vinyl acetate were 0.1 wt .- ^, based on

109839/1705

COPY

the mixture., of neutral or basic copper (II) acetate was added and each system was ^{reacted at 55 °} C. for 60 minutes and for 120 minutes Table IV summarized »'

Table IV Acetic acid ester in the reaction liquid

attempt 3 10 Copper (II) salt neutral
acetate Copper-II- basic
acetate Copper-II 11 reaction time
solvent 60 min » 120 min * 60 mino 120 min, example 12th tertiary butanol track track track track comparison 13th Methanol 11.2 13.0 10.6 12.4 « Ethanol 8.7 10.2 8.1 9.5 n-propanol 7.5 9.2 7.2 8.5 dd sec-butanol 6.1 8.3 5.8 7.6

From the values in the table above it is clear that in the presence of neutral or basic copper (II) acetate an ester interchange between lower aliphatic alcohols, except tert-butanol, and vinyl acetate to a considerable extent Extent takes place, but no such thing with tert-butanol Implementation is taking place «For this reason it is possible that the very

109839/1705

i COPY

achieve favorable results according to the invention, i.e. by using tert-butanol as the solvent Polymerization together with neutral or basic copper (II) acetate or a mixture thereof as a polymerization inhibitor.

Example 4

Vinyl acetate was fed to a polymerization vessel, while the mixture of vinyl acetate and tert-butanol that consists of the reaction mixture had been separated and sucked out of the kettle, was returned to the same vat and wherein overall the weight ratio of tert »-butanol to vinyl · · acetate was adjusted to 0.45. The polymerization was carried out continuously at 40% and atmospheric pressure in the presence of azobis-isobutyronitrile as a catalyst. The received The reaction liquid consisted of 46 parts by weight of vinyl acetate, 45 parts by weight of tert-butanol and 54 parts by weight of polyvinyl acetate To the reaction liquid, 0.01 wt% of the same was added neutral copper (II) acetate added and the mixture in a Polymer! Eat separating barrel transferred. At 110% and 600 mmHg were unreacted vinyl acetate and tert-butanol removed and there · Polyvinyl acetate withdrawn continuously. That at this stage obtained mixture of vinyl acetate and tert-butanol was · in the polymerization tank is operated without cleaning. 2> a · poly · «· Vinyl acetate was dissolved in methanol in a solution with a polymer concentration of 10% by weight. laughs addition of itsnatron

109839/1705

to the polymer solution in such an amount that the Mo ratio of caustic soda to the acetyl groups of the polymer was 0.01, the saponification of the polymer was carried out at a reaction ^{temperature of 50 °} C. for 30 minutes. The degree of saponification of the product was 99 #. The Durchschnittspolymerieationsgrad of the product was 5200. Although the Gewiehtsverhältnls of formed polymers au tert-butanol reached 10 *, no formation or accumulation took a reaction ProductsI of vinyl acetate and tert-butanol in the recycled mixtures of vinyl acetate and tert-butanol instead of _e · The The saponified product was pelletized% using water as an auxiliary, and the discoloration of the pellets was determined by the surface color reaction method according to JIS Z8701. A stimulus value Z of 49 was observed for the pellets. No discoloration of the saponified product was found «,

Example 5

Example 4 was repeated, but basic copper (II) acetate was added as a polymerization inhibitor in an amount of 0.01 1 » f and the mixture of unreacted vinyl acetate and tert-butanol was separated from the polyvinyl acetate at 120 ^° C. and 750 mmHg. Even when the weight ratio of polymer product su tert-butanol reached a value of 5 × 10 *, there was still no accumulation of reaction product from vinyl acetate and tert-butanol. The stimulus value Z of the pellets obtained from the saponified product determined in accordance with JIS 318701 was 46, and discoloration was scarcely observed.

109839/1705

Example 6

17701

Vinyl acetate was introduced into a polymerization vessel together with the recovered liquid odor from vinyl acetate and terto-butanol in a weight ratio of tert.-butanol to vinyl acetate of 0.4. The polymerization was carried out continuously at an ethylene pressure of 30.atu and at 5TC in the presence of aso-bis-isobutyronitrile all catalysts were carried out. The reaction liquid continuously withdrawn from the polymerization vessel was first freed of absorbed ethylene by stripping and then transferred to a polymer separator. The ethylene from the stripping device was returned to the polymerization vessel. The ReaktionsflUssigkeit consisted of 52 weight parts by _e-ethylene Vinylaoetat Oopolymeren, 40 parts by weight Terto-butanol and 55 parts Öew. nloht umgeeetsten-vinyl acetate. 0.005 parts by weight of neutral copper (II) acetate were added to the liquid and the system was transferred to a polymer separator. At 115 ^ and 650 BaHg non-saturated vinyl acetate and tert-butanol were removed from the system and the remaining copolymer was continuously sucked off. The ethylene content of the copolymer was 31.5 mol-jt. The liquid mixture of non-umgesetstem vinyl acetate and tert-butanol in the Polymerisationsgefäfi without any purification just-Bo ₉ as ethylene, surüekgeführt · The copolymer was dissolved "-jl in methanol su a solution having a copolymer content of 25 percent and the Solute the solution of soda ash suggests that the ratio of soda to the acetate groups of the copolymer was 0.3. The saponification was then carried out at 60 ° C

109839/1705

«25-177UI3Z

carried out for 3 hours. The degree of saponification of the product was 98 %. They "polymers, measured in aqueous phenol with a content of 15 wt» inherent viscosity of the saponified Oo "£ of water at 30 ⁰ C,% was 0.125 l / g. The following measurement conditions for the value \ were identical «

Even when the weight "" Yerhältnis of Cοpoly formed "mers to tert _o-butanol value of 4 ι reached 10, no accumulation place of reaction products of vinyl acetate and tert _o ~% butanol in the 71üssigkeitsgemisoh, which was recovered from the Polymerabtrenneinrichtung, instead of. A film of a strength of 25 microns made from the saponified product

ο showed a number of fish eyes of 3 in 100 cm · sas The saponified product contained no built-in polyvinyl alcohol. The stimulus value Z of the pellet made from the dim saponified product, determined by the method of reflection of the surface color according to JIS 701, was 47 *, and no discoloration of the pellets was found. λ

Example 7

Example 6 was repeated, but the following changes were made) Ser Äthylendruok was increased to 59 atu, which at « The ratio of tert-butanol to vinyl acetate was 0.55 and the amount of neutral copper used was "! I" Aoetatβ was 0.01 lb of the reaction liquid · that of ethylene freed · Heaktionsflüeeigkeit consisted of 79 parts by weight of the Ethyl * n «Vinylao · tat copolymers, 55 wt.» Part · η tert ♦ -butanol

109839/1705

17701

and 54 parts by weight of unreacted vinyl acetate. The ethylene content of the copolymer was 57.2 ο1- # and the extent the saponification of the product 97 # · The saponified product had a value / of 0.083 l / g.

The stimulus value Z _{7 of} the pellets made from the saponified product, determined in the same manner as in Example 6, was 48.

Even if the twist ratio of the copolymer is too the tert-butanol reached a value of 2 χ 10, found no accumulation of reaction product from vinyl acetate and tert-butanol in the liquid mixture from the polymer separator was recovered instead. The saponified product also did not contain any polyvinyl alcohol in the mixture and was free from discoloration.

Example 8

Together with the recovered liquid mixture of vinyl acetate and tert-butanol, vinyl acetate was fed to a polymerization vessel in such an amount that the weight ratio of tert-butanol to vinyl acetate was 0.85. The continuous polymerization was carried out at an ethylene pressure of 85 kg / cm at a polymerization temperature of 60 ⁰ C in the presence of ctjOc'-Aeobisisobutyronitril as a catalyst. The amount of catalyst used was 0.3% by weight, based on vinyl acetate restriction. The continuously withdrawn from the polymerization vessel

109839/1706

Drawn reaction liquid was freed from absorbed ethylene and then transferred to a polymer separator. The stripped ethylene was returned to the polymerization vessel. The reaction liquid consisted of 83.5 parts by weight of the ethylene-vinyl acetate copolymer, 80 parts by weight of tert. -Butanol and 51 »6 parts by weight of unreacted vinyl acetate. The ethylene content of the copolymer was 74» 2 mol%. 0.03% by weight of neutral copper (II) acetate was added to the liquid and the system . transferred to a polymer separation device at 117 ⁰ C and 610 mmHg non-umgesetSBtes vinyl acetate and tert-butanol from the mass were removed and the remaining copolymers continuously: deducted · the liquid mixture thereby obtained from nioht unreacted vinyl acetate and tert.-butanol were in the polymerization vessel is returned without cleaning, as is the stripped ethylene.

Even if the weight ratio of formed oil

polymer to tert-butanol reached 10, no accumulation of reaction products from vinyl acetate and butanol was observed.

The copolymers prepared in this way were made by various saponification conditions as given in Table A. are saponified · and those listed in Table A were used obtained saponified products with the specified degree of saponification from the copolymer. The saponified products with saponification values higher than 90 mole # were each formed into 25 micron films. The number of fish eyes appearing in each slide was less than 10 in 100 cm2. 109839/17 05

Ethylene content of the copolymer (MoI ^ t)

Solvent in the de-soaping system

74.2

Table A 74.2 74.2

74.2

74.2

74.2

Methanol methanol ethanol methanol ithanol tert-Bu-

30 wt% 40 wt% 56 32 wt% 50 wt% # 40 wt% tanol

tert-but-toluene tert-but-toluene benzene 100% by weight?

tanol 60 wt .- ^ tanol 50 wt .- # 60 wt .- ^

68 wt .- #

70 wt .- ^ 20.5

Concentration of the copolymer at the start of the reaction (wt .- #)

Soap time (hours) 3.1

NaOH (molar ratio) " ¹ ") 0.7

Terse tempera door ("C) 65

Extent of saponification of the saponified 85.8 product (mol - *)

Discoloration of the saponified product 47 (pellets) -H-)

? ^N number of ⁿ in a ischaugen - foil of 25 microns prepared by Scheeleforaien of the saponified product ·· (per 100 cm2)

21.0

3.0
0.6

60

90.8

46

20.7

5.0 1.0

65

96.3

49

22.0

3.0 0.8

63

97.4

49

22.0

5.0 0.8 65
88.2

2.0 0.4

70

42.2

74.2

n-propanol wt .- # toluene 50 wt .-?

22.0 21.5

6.5 0.8-

70

95.1

47

to

0 »

CO

Vt

+) Molar ratio of itznatron used to that contained in the copolymer Acetate groups

++) S retention according to the stimulus value Z, which is determined by measuring the surface color was determined according to the reflection method and according to JTS Z8701 is specified

CX) K)

As can be seen from the stimulus values Z shown in Table A above, hardly any discoloration became apparent observed the pellets made from the saponified products of the copolymers.

Example 9

The copolymer prepared by repeating the procedure of Example 7 was dissolved in a mixed solvent of 75 parts by weight of methanol and 25 parts by weight of m sec-butanol in such an amount that the concentration of the polymer was 23% by weight. To the copolymer solution prepared in this way, sodium methylate was added in such an amount that the molar ratio of sodium methylate to the acetate groups contained in the copolymer was 0.03. The saponification was ^{carried out at 60 °} C. for 2 hours. The saponified product obtained had a degree of saponification of 95 »6 mol- # and an inherent viscosity of 0.120 · l / g ι measured in phenol with 15 wt .- ^ water content. The stimulus value Z, the pellets produced from the saponified product was 46, and it was observed no discoloration.

Even if the weight ratio of the formed co-

polymer to butanol used reached the value of 2 χ 10 ) no accumulation of reaction products from vinyl acetate and tert-butanol in the recovered liquid

keitagemieoh observed from vinyl acetate and tert-butanol. The number of "piiohaugen" appearing on 25 micron film from the saponified product

108838/1705

2 had been made was only 5 per 100 cm , and it

no incorporation of polyvinyl alcohol into the saponified product was observed.

Example 10

Example 4 was repeated, but the solvent was changed during the saponification of the polyvinyl acetate to ethanol, n- propanol, n-butanol, isobutanol and sec-butanol. A saponified polyvinyl acetate with a degree of saponification of 97.99 # corresponding to Example 4 was obtained in each pail. All products were completely free from discoloration.

109839/1705

Claims (1)

Claims 1.) Method of making a complete or partially saponified polyvinyl acetate or such a vinyl acetate-ethylene copolymer by polymer * Sation of vinyl acetate alone or together with ethylene in an organic solvent in the presence of "known Polymerization catalysts with the formation of polyvinyl acetate or vinyl acetate-ethylene copolymers, the ™ contain no more than 80 mol% ethylene, heating the Reaction mixture with evaporation of the organic solvent, addition of at least one in the polymer Acetate residues contained equimolar amount of a low aliphatic saturated alcohol and saponification of the product in the presence of an alkali catalyst, characterized in that the polymerization in tert-butanol is carried out as an organic solvent until the conversion of the vinyl acetate into polymer 15 to | 90 wt .- # achieved that neutral or basic copper (II) acetate is added to the resulting mixture containing the polymer, the mixture is then heated and the it contains tert-butanol and monomeric vinyl acetate be evaporated and recovered 2.) The method according to claim 1, characterized in that the monomeric vinyl acetate and the tert-butanol, such as ele have been won, returned and used for the next Circuit can be used. 109839/1705 or 2 3.) Process according to claim 1, characterized in that the polymerization is terminated when the conversion of the vinyl acetate into polymer reaches 20 to 80 » . 4.) Process according to claim 1 to 3, characterized in that the ethylene up to a content of vinyl acetate-ethylene copolymers is implemented from below 61 Mol- #. 5.) Process according to claim 1 to 4, characterized in that the lower aliphatic saturated alcohol an aliphatic saturated alcohol to the saponification step with less than 4 carbon atoms is added. 6.) The method according to claim 5, characterized in that that methanol is added as the lower aliphatic saturated alcohol. 7.) The method according to claim 1 to 6, characterized in that the heating to evaporate vinyl acetate and tert-butanol at a higher temperature than the boiling point of the vinyl acetate under the pressure applied during heating, but lower than 150 ⁰ C, is carried out . 8.) Process according to claim 1 to 7, characterized in that a weight ratio of tert-butanol to vinyl acetate in the range from 0.1 to 7 is used in the solution polymerization of the vinyl acetate. 109839/1705