DE1165850B - Polyvinyl fluoride dispersions for the production of films - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: C08f

Number:
File number:
Registration date:
Display day;

German KL: 39 b -22/06

P 23158IV c / 39 b
July 14, 1959
March 19, 1964

Molecularly orientable polyvinyl fluoride films can be prepared as described in U.S. Patents 2,419,008, 2,419,010, 2,510,783, and 2,599,300. The known processes for producing such films, however, have considerable deficiencies, in particular this is the case when high molecular weight polyvinyl fluoride is to be processed into films with good physical properties. Even above the crystalline melting temperature of the comminuted polymer, this starting material has such a high melt viscosity that it is not possible to produce a film by extrusion from the melt, which is otherwise customary. It was not possible to improve the flowability of these melts by increasing the temperature, since ^{thermal decomposition occurred at temperatures above about 220 °} C., which was noticeable by a brown discoloration of the film. Even with the use of very heavy extrusion presses it has not been possible to date to process the high molecular weight polyvinyl fluoride from the melt into films.

It was therefore obvious to eliminate these difficulties through the casting process, so one Cast the solution of the polymer on suitable surfaces to form a film and then the Evaporate solvent. However, the transfer of the film casting technique to polyvinyl fluoride stood still the fact that this is in the usual volatile solvents such as acetone, petroleum ether, Isooctane, xylene, carbon tetrachloride, chloroform, methanol, ethanol, was insoluble. That for film production particularly suitable high molecular weight polyvinyl fluoride with a high inherent viscosity only dissolves to a small extent in hot solvents such as hot dimethylformamide, tetramethylene sulfone, Nitroparaffins, cyclohexanone, dibutyl ketone, mesityl oxide, aniline, phenol, methyl benzoate, phenyl acetate and diethyl phosphate. Despite all the advances in the use of hot solvents For the film casting technique it cannot be overlooked that this method of operation has considerable difficulties in terms of apparatus offers and requires special security measures.

In addition, all molecularly orientable polyvinyl fluorides do not have the same low solubility. The orientable polyvinyl fluorides produced by the processes of US Pat. Nos. 2,510,783 and 2,599,300 cannot be dissolved even in the area of low molecular weights, even in hot solvents. As the molecular weight of the polymer increases, it becomes more and more difficult to bring it into solution, so that un-polyvinyl fluoride dispersions are ultimately used for production
of foils

Applicant:

E. I. du Pont de Nemours and Company,

Wilmington, Del. (V. St. A.)

Representative:

Dr.-Ing. A. v. Kreisler, Dr.-Ing. K. Schönwald
and Dr.-Ing. Th. Meyer, patent attorneys,
Kohl 1, Deichmannhaus

Named as inventor:

James Simpson Proctor, Amherst, Mass.

(V. St. A.)

Claimed priority:

V. St. v. America July 16, 1958

(No. 748 795)

dissolved polymer is present in gel form even at the boiling point of the solvent. The production uniform polyvinyl fluoride films by casting from solutions of the high molecular weight polymer however, it is impossible if a gel-like product is also processed. When forming a film by casting from solutions is generally worked with relatively low efficiencies, for example only 45 to 113 g of film can be obtained from about 454 g of the polymer solution. The casting technique also requires measures and equipment for rapid and as complete as possible recovery of the solvent and its return to the process. In addition, one is forced to take special precautionary measures to eliminate the toxicity and flammability of the solvents.

It has now been found that dispersions consisting mainly of polyvinyl fluoride can be made from finely divided polyvinyl fluoride and / or copolymers of vinyl fluoride and other ethylenically unsaturated Use monomers with dimethyl sulfoxide as a dispersant for the production of films can. Preference is given to using copolymers which are at least 75 percent by weight Contain vinyl fluoride. According to one embodiment of the invention, dispersions are used in which

409 539/579

based on their total weight, 5 to 85 percent by weight of polyvinyl fluoride are present. It turned out to be special proven to process dispersions in which the polyvinyl fluoride used has an inherent viscosity of at least 0.35.

This overcomes the difficulties identified. You get one that is self-supporting Films deformable, film-forming, mainly composed of polyvinyl fluoride mass, which can withstand good Processing throughput speeds by extrusion into perfect and uniform foils leaves. The dispersion enables the processing of polyvinyl fluoride with a relatively high inherent viscosity in the range of temperatures at which no thermal decomposition occurs.

Dimethyl sulfoxide hardly dissolves polyvinyl fluoride at room temperature, at elevated temperatures However, this connection causes the finely divided polyvinyl fluoride to melt together, i.e. it represents a latent solvent for this polymer.

The amount of polyvinyl fluoride present in the dispersion must depend on the casting process to be used be turned off. If you want the mixture of finely divided polyvinyl fluoride and Press the dimethyl sulfoxide into a hot oil bath with the help of an extruder, so that 25 to 40 percent by weight, preferably 30 to 35 weight percent polyvinyl fluoride is present in the dispersion. Presses However, the mixture at room temperature on a pad or tape and heated on the Air to melt together, so it is best to work 10 to 60 percent by weight, preferably 30 up to 40 percent by weight of polyvinyl fluoride in the dispersion. You work with 20 to 85 percent by weight, preferably 40 to 60 weight percent polyvinyl fluoride in the dispersion when the mixture is used is pressed in the form of a hot melt into a cold quenching bath.

According to the proportions of the individual components present in the mixtures, flaky, moist, free flowing powders, heavy pastes and liquids in viscous or free flowing form. The mixtures are preferably used in the form of dispersions, the solid polymer being used mixed with the dimethyl sulfoxide using conventional mixing methods. The mixing time depends on the type of mixing device used, the size of the batch and the proportion of dimethyl sulfoxide used.

Monoethylenically unsaturated monomers which can be copolymerized with vinyl fluoride and processed according to the invention are: ethylene, propylene, Isobutylene, styrene, halogen-substituted ethylene, such as vinyl chloride, vinyl bromide, 1,1-dichloroethylene, 1,1-difluoroethylene, Difluorochloroethylene, trifluorochloroethylene, tetrafluoroethylene, trifluoropropylene and difluoroisobutylene; Vinyl esters, such as vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate, vinyl stearate, Vinyl salicylate and vinyl esters of inorganic acids; Vinyl ethers, such as vinyl ethyl ether, tetrafluoroethyl allyl ether and vinyl dioxolane; Vinyl ketones such as methyl vinyl ketone; N-vinylimides, such as N-vinyl succinimide and N-vinylphthalimide; Acrylic acid and methacrylic acid and their derivatives, such as esters, amides, anhydrides and acid halides including methyl methacrylate, jS-hydroxyethyl methacrylate, AlIyI methacrylate, n-butyl methacrylic acid amide; Derivatives of maleic and fumaric acids, such as diethyl maleate and dimethyl fumarate; Propenyl esters such as allyl acetate and Isopropenyl acetate.

In the examples below, polyvinyl fluorides with different inherent viscosities are used.

To measure the inherent viscosity, the polyvinyl fluoride is stirred and heated vigorously dissolved in hexamethylphosphoric acid amide. The solution is cooled to 30 ° C and its viscosity with the Viscosity of the solvent treated in the same way compared. So you determine the outflow time from a viscometer for the solvent containing no polymer and for the polymer solution.

The inherent viscosity is calculated as follows:

T Relative viscosity = - ^ -.

Hisrin means T ₀ the outflow time of the solvent in seconds and T ₁ the outflow time of the polymer solution in seconds.

The inherent viscosity then results from the following relationship:

^. . . . . natural logarithm of the relative viscosity Intrinsic viscosity = -

where C is the concentration given in grams of the polymer per 100 cm ^{s of solution.}

In all examples, the following value applies to the concentration C: C = C, 05 g / 100 cm ³ .

The following examples illustrate the invention. Unless otherwise stated, all are Quantities are to be regarded as weight information.

example 1

510 parts of dimethyl sulfoxide were placed in a Waringe mixer given and in the with 500 to 1000 revs: / min. rotating mixer 240 parts of finely divided polyvinyl fluoride (intrinsic viscosity: 2.6) given. Mixing was continued at this speed for 20 minutes, Care was taken to ensure that no temperature increase occurred.

After a final, brief, at about rev./min. The resulting dispersion, containing 32 percent by weight of polyvinyl fluoride, was poured into a flat vessel in order to create the largest possible surface area per unit volume.
The dispersion was then freed of entrapped air bubbles using a high vacuum overnight. The deaerated dispersion was fed to a storage vessel equipped with a slit-shaped, oil-cooled pouring funnel, the mouthpiece of which is approximately 0.16 to 0.31 mm deep in a heated liquid bath filled with colorless mineral oil.

Using a positive air pressure of about 0.35 kg / cm ² , the dispersion was pressed through the funnel mouthpiece, which was set to a slot about 300 microns wide, into the oil bath kept at 157 ° C. When it emerged from the casting device, the dispersion melted together immediately to form a self-supporting film, which after

5 6

Run an approximately 2.5 to 5.1 cm long oil bath flexible tubing one on the surface of a

stretch into a cool, highly polished endless steel band containing a colorless mineral oil

bath of 30 ° C was performed. Supplied by washing with. The steel belt ran at a speed

Acetone was adhering mineral oil and dimethyl speed of about 0.61 m / min. It fed the dispersion

sulfoxide extracted from the film and this for the purpose of 5 next under a vertical direction adjustable,

Air drying clamped in a frame. sloping scraper and then

_. . . ₉ relatively low linear velocity in

Example / _a nitrogen-filled section where they

A 40 percent by weight produced analogously to Example 1 was heated rapidly to 140.degree. In this procedure

cent of finely divided polyvinyl fluoride containing di- io could produce a tough, flexible film continuously from the

Spersion with dimethyl sulfoxide was removed from the circumferential steel band for 2 hours,

vented in a high vacuum. The poly used. .

merisat had an inherent viscosity of 2.6: The Di Example 4

Spersion was made from the reservoir of a strand using a polyvinyl fluoride with a

press under an air pressure of 0.7 kg / cm ² in 15 inherent viscosity of 4.9 was a 10 weight percent

an oil bath kept at 182 ° C pressed. Analogous to the dispersion in dimethyl sulfoxide containing solid

Game 1, a self-supporting structure analogous to Example 1 was formed immediately. After venting

Film that was poured from the molten bath into a 30 ° C this smooth, easy-flowing dispersion on a

holding cooling bath was passed. flat, polished steel plate injected into one

After leaving the cooling bath, the oil ao 13O ⁰ C was brought held a drying cabinet. To

wiped off and the film after clamping in a 90 second drying time melted the polyvinyl

Frame for 25 minutes to allow the fluoride parts to volatilize to form a translucent

Dimethylsulfoxyds exposed to a stream of hot air. Gelfilmes together, whereupon the bulk of the

. originally present Dimethylsulfoxyds still

B e 1 s ρ 1 e 1 3 ₃₅ containing film by immersing the steel plate in

350 g of finely divided polyvinyl fluoride was quenched with its own cold water. The one from the plate

viscosity of 2.2 were removed with 650 g of dimethyl sulfoxide film was placed in a frame.

roughly forming a 35 weight percent tight to prevent shrinkage, and then

mixed substance containing mass. The mixture for the purpose of volatilization of the dimethyl sulfoxide with

was treated with a water jacket-lined cylinder in a stream of hot air. The solvent

Drischen container made of stainless steel fed, the free film was then again in cold

next to the bottom one quenched with a sieve of 74 to water and taken out of the frame.

49 micron mesh opening. The film that is now about 51 microns thick

At the center of this container was a shaft that was quite tough and pliable.

Arranged 12.3 mm in diameter, the three ring-35.

wore shaped, 6.35 mm thick running disks. The wave B e 1 s ρ 1 e 1 5

was driven by a Vä-PS electric motor. Analogous to example 3 was a 60 weight percent

Then about 1000 g of a carefully washed solids-containing dispersion of polyvinyl

and dried "Ottawa" sand of the grain size fluoride with an inherent viscosity of 2.2 and dimethyl

between 0.59 and 0.84 mm filled into the container, 4 ° sulfoxide produced, which after venting to a

so that about a third of the free space was sprayed onto this flat polished steel plate. the

The cylinder was filled with sand. Plate was in one on for about 1 ^x / _{2 minutes}

The Ottawa sand is a drying cabinet kept at 165 ° C. Under Sand found near Ottawa, Illinois, USA, these conditions melted the polyvinyl fluoride according to ASTM Directory C-190 as the standard 45 particles to a translucent gel film is used for testing concrete. together, which is still the bulk of the originally This sand has a high silicate content of the present dimethyl sulfoxides. The film 99 percent by weight and more, which was now essentially achieved by immersing the steel plate in any individual particles of silicate crystals or parts quenched by cold water, taken from the plate Represent silicate crystals. 50 and clamped in a frame in order to

The agitator shaft ran at 1800 rpm for 8 minutes to avoid shrinkage. Eventually the movie was min. During this time an intimate mixture of sand and powder was created by the rotating discs in a circulating air drying cabinet, in order to volatilize the dimethyl sulfoxide, which flowed downwards in the direction of the outlet opening which was next to the floor and which was removed from the drying cabinet where 55 film quenched in cold water was after removal, the sand was removed through the built-in fine sieve of the tenter frame about 302 microns thick,
was held while a uniform, smooth,. .
agglomerate-free dispersion of polyvinyl fluoride in example 6
Dimethyl sulfoxide emerged, which was collected in a collector 3.63 kg of finely divided polyvinyl fluoride with a container at a temperature of about 25 ° C. and an inherent viscosity of 2.5 was trapped with 0.91 kg of dimethyl. Cooling water Ge Hobart mixer was passed through the cylindrical sulfoxide tank for 14 minutes in a "Model-A-200-encased water jacket" in a planetary orbit, at a speed of 86 rpm during the mixing process. and to switch off a sudden rise in temperature. The speed of 198 rev / min. mixed. The dispersion was deaerated for a few hours under a high vacuum containing 65 weight percent solids. Dispersion showed a moist, powder-like consistency. After the venting, the present smooth she was fed to a heated extrusion press and dispersion at about room temperature by a slot held ^{from this by an ajf 185 0 C}

shaped steel pouring funnel continuously pressed in the form of a hot, molten gel into a water bath kept at about 10 ° C. It The result was a tough, flat film about 126 microns thick.

5 Example 7

Analogously to Example 6, a dispersion containing 48 percent by weight of solids was prepared from polyvinyl fluoride with an inherent viscosity of 3.2 and dimethyl sulfoxide. This dispersion was significantly more flowable than that of Example 6. As described, it was pressed into a film at 160.degree. C. and quenched in a water bath kept at 10.degree. The resulting tough, flexible film was treated with a stream of hot air for 10 minutes, after which a ¹ ½ virtually solvent-free, approximately 302 micron thick film was obtained.

Example 8

Analogously to Example 6, a ^{dispersion containing 25 percent by weight of ao} solids was prepared from polyvinyl fluoride with an inherent viscosity of 4.9 and dimethyl sulfoxide. This was extruded at a temperature of the sprue of about 160 ° C as described in Example 6 into a film and chilled in an maintained at about 8 ⁰ C water bath. After treating the clamped film with a stream of hot air for 10 minutes, a substantially solvent-free film about 151 microns thick was obtained.

The great advantage of the invention lies in the versatile use of dimethyl sulfoxide, which can be mixed with polyvinyl fluoride in practically all proportions. At room temperature Dimethylsulfoxide is liquid, so that it can be mixed perfectly without additional costly Heating is possible. You can proceed according to the invention with good throughput speeds, without requiring special equipment and without fear of ... degradation of the polymer have to. The invention is made particularly valuable by the possibility of using high molecular weight polyvinyl fluoride to process.

According to the invention, not only films can be produced, but also other shaped bodies, such as, for example Fibers, threads, rods and tubes.

Dimethyl sulfoxide is completely thermally stable below the boiling point. It works on most materials practically non-corrosive. There are also no special precautions to be taken to protect one To counteract toxicity or flammability of this compound.

Claims (4)

Patent claims: 1. Use of finely divided dispersions consisting mainly of polyvinyl fluoride Polyvinyl fluoride and / or copolymers of vinyl fluoride and other ethylenically unsaturated Monomers with dimethyl sulfoxide as a dispersant for the production of films. 2. Use of dispersions according to claim 1, characterized in that the copolymer at least 75 weight percent vinyl fluoride is present. 3. Use of dispersions according to claim 1 and 2, characterized in that, based based on the total weight of the dispersion, 5 to 85 percent by weight of polyvinyl fluoride are present. 4. Use of dispersions according to claim 1 to 3, characterized in that the The polyvinyl fluoride used has an inherent viscosity of at least 0.35. Considered publications:
French Patent Nos. 1058152, 1121288; British Patent No. 653 256;
U.S. Patent No. 2,419,008;
Schildknecht: »Vinyl and Related Polymers, 1952, pp. 444 and 445. 409 539/579 3.64 © Bundesdruckerei Berlin