DE2035362B2 - Process for the production of moldings from purified saponification products of ethylene-vinyl acetate copolymers - Google Patents

Description

Adding a precipitating agent, such as water, to the solution by steam distillation, as described in U.S. Patents 2,386,347, 2,399,653 and 2,403,464, or by cooling the Solution.

In the method of cooling the the saponification product containing solution, the loss of polymer in the separation operation is so high such as more than 5 percent by weight, and the isolated polymer is extremely fine in particle size thereby causing significant loss of polymer in isolation, washing and drying will. On the other hand, although in the method with the addition of a precipitant to the solution of the Saponification product, the loss of copolymer in the separation operation is low, the copolymer isolated in this way however, agglomerates easily due to its strong cohesive force and is difficult to operate more effectively Way to wash and dry, if it is not ground or pulverized beforehand, and the so obtained dry product is in the form of a powder with a lower apparent density of about 0.2 to 0.4 before. When this powder is subjected to molding or melt spinning, it is often a Venting is required to remove air present in the molten polymer, and it therefore, rods for use in melt spinning are precast and preformed before films or threads can be made.

The invention is based on the object of providing a method for producing molded bodies are heat-resistant, have good mechanical toughness and high elasticity, from purified saponification products to create ethylene-vinyl acetate copolymers from the solution.

According to the invention this object is achieved in that one

1. the above-mentioned saponification solution is water mixed in such an amount that the limit of gel formation and deposition of the saponified copolymer has not yet been reached from the solution at the temperature of this solution will,

2. the resulting aqueous-methanolic solution of the saponified copolymer in a mixture of water or a mixture of methanol and water existing coagulation bath extruded, the one has a lower methanol concentration than the extruded solution,

3. deforms the saponified copolymer,

4. the moldings obtained for removing sodium acetate or potassium acetate and the remainder alkaline catalyst washes out and dries.

In the process according to the invention, the shaped bodies are in the process of washing, drying and the like Processes easy to handle, and there is very little loss in the separation process Polymer.

The preferred concentration of the ethylene-vinyl acetate copolymer treated according to the invention is in the range of about 25 to 50 percent by weight. The molar ratio used to carry out the saponification an alkaline catalyst to the copolymer is in the range of about 0.005 to 0.5, based on the number of moles of acetic acid residues contained in the copolymer.

The amount of water added to the methanol solution of this saponified ethylene-vinyl acetate copolymer must be within the range in which this saponified copolymer is in solution at a temperature between 35 ° C and the boiling point of an aqueous methanol mixture the addition of water is not yet precipitated by gel formation. That means that after the Always adding water to the saponified copolymer

ίο still remain dissolved in the aqueous methanol solution got to.

If this saponified copolymer comes into contact with the solution of the coagulation bath, so it coagulates within minutes with minimal loss of polymer in the deposition process and results in microporous films or fibers that can be easily handled.

If the copolymer is dissolved at a high temperature and then cooled, it reaches a temperature at which the polymer is partially deposited, but this temperature does not necessarily correspond the solution temperature of the polymer. In this polymer solution, a so-called "delayed" occurs Separation «. Hence the term "means necessary to dissolve the saponification product Water «an amount of water that is necessary to keep the polymer in a non-separated state. The amount of water required to dissolve the saponification product basically depends on the ethylene content and the degree of saponification of the copolymer, the polymer concentration of the saponified copolymer and the temperature of the solution.

In the most effective embodiment of the invention Process is the ethylene-vinyl acetate copolymer by adding an alkaline Catalyst to a 25 to 50 weight percent methanol solution of the ethylene-vinyl acetate copolymer in a molar ratio of 0.005 to 0.5 based on this depending on the composition Polymers present in the copolymer acetic acid residues saponified, which if necessary after Focus can be done. Then such an amount of water as is required that the saponified Copolymers is dissolved at the temperature of this solution, or such an amount of water is added that is sufficient to prevent the separation of the saponified product, leaving an aqueous methanol solution is obtained which saponify 15 to 45 percent by weight, preferably 20 to 40 percent by weight of this Contains copolymers. The solution is then passed through a slot nozzle with a for the desired thickness a plate or sheet of suitable width is extruded into a coagulation bath solution or it becomes a film of the solution of the saponification product to a thickness of 1 to 10 mm on a flat plate and then the film is shaped in a coagulation solution or the solution of the saponification product is through a nozzle with an opening diameter suitable for the desired diameter of a thread is extruded into a coagulation solution, a strand of 1 to 10 mm in diameter being formed will. If the concentration of the copolymer in the aqueous methanol solution is too low, it is impossible to coagulate the copolymer in the form of a film or a strand when, on the other hand, the If the concentration is too high, the product shows a lack of porosity. Hence a concentration of this saponify Copolymers in the aqueous methanol solution

5 6

in the range of 15 to 45 weight percent desirably weight percent methanol and 70 weight percent

value. Water at 15 ° C. The coagulation of the

The coagu-extruded solution to be used according to the invention took place within 7 minutes

lation bath solution is a mixture of methanol and complete. It became a microporous sheet of the

Water or water alone is desirable. Particularly 5 dimensions 30 cm x 12 cm x 2 mm obtained,

A mixture of methanol and, since the plate had a microporous structure, was well suited

Water that contains 10 to 50 percent by weight of methanol they are easy to wash out and dry,

contains. It is necessary that the methanol concentration after washing with water to remove

tration in the coagulation bath solution equal to the sodium acetate and after drying had the

or lower than that of the extruded aqueous sheet obtained a tensile strength of 23 kg / cm ² ,

Methanol solution is. A higher concentration of methanol - an elongation of 310% and an apparent density

Tration is undesirable because it results in a loss of about 1.0.

saponified copolymer during the deposition By cutting this plate with the help of a Process in the coagulation bath solution is increased. Pelletizer, pellets are obtained which are used for The temperature at which the solution of the saponified 15 production of foils or threads are suitable. Copolymers with the coagulation bath solution in The loss of copolymer on separation in contact should be lower than the manuring process in this case was 0.2 weight temperature lie at which the copolymer in percent.

Coagulation bath solution is insoluble. A lower level is η i e 1 2

Temperature is desirable to avoid loss at 20

to keep the deposition process as low as possible. 100 g of an aqueous methanol solution of saponified

A temperature of 10 to 30 ° C is generally ethylene-vinyl acetate copolymer, which according to the im

preferred. The method described in Example 1 obtained in the manner described has been obtained

Sheets or sheets and strands are microporous and have been through a nozzle with a diameter of 5 mm

easy to wash out, and the loss in 1 kg of the coagulation properties specified in Example 1

separation process is a maximum of 0.8 weight bath solution extruded. The copolymer was in

percent or less than Ve of the loss deposited and coagulated in the form of a strand,

conventional procedure in which the solution is being required 4 minutes for coagulation

is merely cooled occurs. With a coagu ware. The product obtained in the form of a strand

lation bath solution that was microporous and easy to wash out at a temperature of 30

is kept above 50 ° C, it is impossible, after drying with the help of a pelletizing or

to carry out the method according to the invention. Tableting device in suitable for deforming

The pellets or tablets are cut up in the manner indicated in the form of a film. The apparent

Product obtained or plate can be in the original density of that in the form of tablets

borrowed shape or after cutting into bars 35 product was 0.99. During the deposition

or pellets are washed and dried. A loss of 0.5 percent by weight of the operation occurred

The product in the form of a strand may contain copolymers.

also in this form or after cutting B is η ie 1 3
washed in pellets and dried.

The invention is detailed below under 40 An aqueous methanol solution of the saponified ethylene reference on the following examples described- vinyl acetate copolymers, which are prepared by the method of ben. Example 1 was obtained, was on an Example 1 glass plate with 3 mm frame height and a size

from 15-15 cm and poured immediately into 400 g of a

40 parts of ethylene-vinyl acetate copolymer immersed in a coagulation bath solution held at 45 ° C., content of 32.5 mol percent ethylene units, 70 parts which consisted of 10 percent by weight of methanol and 90 percent by weight of methanol and 4 parts of caustic soda were weight percent water. The coagulation took place in a solution mixed with one another and for 15 minutes. This gave a sheet of soaps of this copolymer with the conventional dimensions 15 cm × 15 cm × 1.2 mm, the saponification method was microporous and easy to wash out for 3 hours at 60 ° C., and one was heated. During the progress of the reaction tensile strength of 15 kg / cm ² , an elongation of, a mixture of 12 parts of methyl acetate and 410% and an apparent density of 0.89 was had. Distill 5 parts of methanol from the reaction system. The loss of the copolymer in the separation. The degree of saponification of the saponified ethylene process was about 0.4 percent by weight.
Vinyl acetate copolymers in the obtained methanol 55.
solution reached 98.5 mole percent. Example 4

The solution thus obtained was then heated by heating 200 parts by weight of a copolymer of 28 mol

so concentrated that the content of this copoly- percent ethylene, 70 mol percent vinyl acetate and

meren was 40 percent by weight. 2 mole percent acrylic acid was in 400 weight

26 parts of water were dissolved at 6O ⁰ C into 100 parts of the 60 parts of methanol, the mixed 15 parts by weight kaukonzentrierten solution. The saponified soda were added and reacted at 6O ⁰ C during ethylene-vinyl acetate copolymers in the 2 hours obtained. The obtained saponification solution, solution was not deposited under the specified conditions which had a degree of saponification of 96 mol percent of copolymer concentration, degree of saponification and 28 mol percent ethylene and 2 mol percent acrylic temperature. acid units contained, was to a content of

100 g of the solution obtained were ^{concentrated from a slot 5 to} 35 percent by weight of this copolymer,

nozzle 3 mm thick and 30 cm wide in 1 kg of 100 parts by weight of this concentrated copoly-

Coagulation bath solution extruded, 25 parts by weight of water were added to the 30 gel solution,

so that an aqueous methanol solution of the copolymer at a temperature of 60 ⁰ C was formed. 100 g of this copolymer solution were extruded through a slot nozzle of dimensions 30 cm × 4 mm into a coagulation bath solution which consisted of 20 percent by weight of methanol and 80 percent by weight of water and was kept at 25 ^° C. It took 13 minutes to complete the coagulation. A 3 mm thick plate was obtained. This plate had a microporous structure and was easy to wash free of sodium acetate and easy to handle during washing and drying. The loss of copolymer in the deposition process was 0.3 percent by weight. Before drying, the plate was cut into pellets or tablets with the aid of a tablet machine and then dried. The plate was also cut into similar tablets after drying. The apparent density of the product was 0.95.

Example 5

100 g of an aqueous methanol solution of ethylene vinyl alcohol copolymer, which while complying with a Degree of saponification of 97.2% by treating ethylene-vinyl acetate copolymer with a content 38 mol percent of ethylene units had been obtained by the method of Example 1, was by a Slot nozzle measuring 30 cm by 3 mm in

ίο a coagulation bath solution of 15 percent by weight methanol and 85 percent by weight water, which was kept at 14 ° C, extruded. Complete coagulation within 6 minutes gave a plate which was microporous and extremely easy to wash free of sodium acetate and similar impurities. This plate had a tensile strength of 25 kg / cm ² and an elongation of 290%. 0.3 percent by weight of the polymer was lost in the deposition process.

409 515/425

Claims (5)

1 2 vinyl acetate copolymers of the general formula Claims: (C2H4) X (CH2CHOCOCH3) y (CH2CRR ') t, 1. A process for the production of moldings in which R is a hydrogen atom or a methyl group from purified saponification products of ethylene 5 and R 'is a methyl or vinyl group or - COOR, vinyl acetate copolymers from the solution, the - C ₈ H ₅ , - C or - CN denote the ratio by known saponification of ethylene-vinyl (Y + Z) : X within the range from 1.5: 1 to acetate copolymers of the general formula 3: 1 and the Z: Y ratio within of the area (ru \ rru runrnrii \ ίητι γώώ '\ ^{from 0: 1 to 0} ^ ^{: 1 lie} &> ^until reaching a (C ₂ HJX (LH ₂ LHULULH ₃ J ₇ (LH ₂ LKK) _{z, lo se} if _U ngsgrades of more than 90 mole percent in the opposite in which R is a hydrogen atom or a methyl wart of methanol with the help of an alkaline catalyst group and R 'is a methyl or vinyl group or lysators. - COOR, - C ₆ H ₅ , - C or - CN mean, the aim of the invention is to produce purified ethylene the ratio (Y + Z): X within the range of vinyl alcohol copolymers with good film formation from 1.5: 1 to 3: 1 and the ratio Z: Y within 15 or fiber-forming properties. goal of half of the range from 0: 1 to 0.1: 1, up to the invention it is also made from pellets or chips Achieving a degree of saponification of more than ethylene-vinyl alcohol copolymers accessible to 90 mole percent in the presence of methanol with make the slightly higher apparent specific With the help of an alkaline catalyst, the density is about 0.7 to 1.2 and a microporous structure has been, characterized, have 20 and for the production of foils, plates that one or threads according to various processes, in particular 1. the saponification ^{solution obtained is admixed with} water in the pouring process or the melt in an amount such that the boundary spinning process from the saponified copolymer of gel formation and deposition of the are suitable. saponified copolymer from the solution at ²⁵ ^ s is known, saponified Athyjen vinyl acetate or temperature of this solution is not yet achieved polymers by saponifying ethylene vinyl acetate copolymers with an alkaline catalyst, such as 2. the resulting'wäßrig-methanolic solution of sodium hydroxide or potassium hydroxide in counter-saponified copolymer in a from Wasser ™ ^T \ ^of lower aliphatic alcohols, such as or a mixture of methanol and water 3 ° methanol or ethanol to produce. After the coagulation bath consisting extruded, the hydrolysis to the desired degree by a lower methanol concentration has ff ^{f Uh} rt ^was' ™ ^{rd he} _u ^aimed ethylene-vinyl alcohol and the extruded solution copolymer was isolated, which, for example, through water 3. deform the saponified copolymer, steam distillation to remove the lower aliphatic 4. the moldings obtained can be used to remove alcohols, wash the remaining poly-sodium acetate or potassium acetate ^and dry it,
^{It is} also well known to wash and dry sheets and plates. ^{or threads from the} saponified copolymers obtained by casting processes or by melt spinning, 2. The method according to claim 1, characterized in that 40 wet or dry spinning processes are obtained, characterized in that the aqueous-methanolic These methods are for example in the USA. Solution of the saponified copolymer by patents 2,386,347,2399,653,2 403 464 and the addition of water to the saponification solution are described in one of British Patent 1120 189. Temperature between 35 ^° C. and the boiling point. In this saponification, the aqueous methanol solution is generally produced with caustic. 45 Soda or sodium hydroxide as an alkaline catalyst 3. The method according to claim 1 or 2, characterized used sator. The predominant proportion of the caustic soda used for the saponification reaction in the coagulation bath, which is used at a temperature in the range from 10 to 30 ^° C., is converted into sodium during this reaction, converted into acetate and after the isolation reaction 4. The method according to any one of claims 1 to 3, 50 saponified copolymers from the solution are so characterized in that the Methanolkonzen- obtained sodium acetate and remaining caustic tration in the methanolic coagulation bath soda in an amount of a few percent in the Solution is 10 to 50 percent by weight. contain saponified copolymers. The sodium acetate 5. Use of the according to one of claims 1 and the caustic soda cause deterioration 4 obtained moldings of the apparent change in the quality of the saponified copolymer, such as Density of about 0.7 to 1.2 in the form of pellets Discoloration, degradation of the polymer and change or chips of microporous structure to make this polymer soluble in the solution of Foils or threads. middle. The discoloration of these copolymers often occurred when the polymers were melt spinning or casting and subjected to heat treatment. In order to prevent this discoloration, it is very desirable to have the separated copolymer immediately wash with water after separation. The invention relates to a method for producing 65 The separation or isolation of the saponified of molded bodies made from purified saponification products, ethylene-vinyl acetate copolymers from saponification Ethylene-vinyl acetate copolymers from the solution is generally after a conventional solution, carried out by known saponification of ethylene ionic processes, for example by