DE2458390A1 - METHOD AND DEVICE FOR MANUFACTURING SHORT FIBRILS - Google Patents

Description

PATENT LAWYERS

DR. INCA-VANDERWERTH Dk. FRANZ LEATHER

(1934-1974) β MÖNCHEN 8O

LUCILE-GRAHN-STR. 22 TEL. (089) 47 39 47

Munich, November 25, 1974 p.73 / 7O-7V2O-7V34- comb.

SOLYAY & CIE.

33 Rue du Prince Albert, Brussels, Belgium

Method and device for the production of short fibrils

The invention "relates to a process for the production of Fibrils of short length and devices that are particularly suitable for its implementation.

It is already known by sudden expansion of a liquid two-phase mixture based on molten Polymer and solvent, which is at increased pressure and elevated temperature located, continuous, fibrillated Create structures or strands. However, such structures are very difficult as such, mainly because of because of their extremely high volume and the speed with which they are manufactured. this is the reason that you have to get to them in an economical manner

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TEtEORAMMEi L E D E R E R P AT E N T MUNICH

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To be able to continue using them, first of all a chopping treatment undertakes, which although its dimensions are reduced, but is detrimental to its physical properties. Such a chopping treatment also requires extensive Plants and considerable energy consumption »

Therefore, attempts have been made to develop procedures which directly lead to the formation of fibrils with short Length result in the sudden relaxation of the aforementioned mixtures.

So is in the Belgian patent 787 032 of the applicant a procedure for the direct production of short fibrils described in which the two-phase mixture is dispersed in an additive fluid just at the time it is subjected to the sudden relaxation. According to the Procedure of the applicant's Belgian patent 787 033 a similar result is achieved if the formed by the sudden relaxation of the two-phase mixture, fibrillated structure at the time of their. Formation is chopped up by a flow of a transverse fluid.

Although these prior art procedures are essential to the technique of making discontinuous fibrils improve, they still have some tile parts. A major disadvantage is the need to use very large ones Amounts of make-up fluid to achieve adequate chopping or grinding.

The object of the invention is therefore to create a method for the direct production of short fibrils, which is not more requires the supply of an additional fluid.

Furthermore, in the Belgian patent 811 780 of the applicant a procedure for producing short

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Fibrils ", which consists in the exit or Ejection cone, which forms at the outlet of the opening, by means of which the sudden relaxation is brought about, to be atomized mechanically. However, this mode of operation requires the use of mechanical devices such as B. rotatable blades rotating at a very high speed or cutting at a very short distance from the relief opening. From this it follows that this way of working, which enables good results to be achieved, is only very difficult to carry out, for which purpose special driver devices are required and where as a result of mechanical Defective downtimes are possible.

It follows from this that, despite the large ones achieved so far Advances still no safe process exists which does not have an additional fluid for the direct production of short fibrils by sudden relaxation of two-phase mixtures of molten polymers and solvents.

The object of the invention is to create a method which does not have the aforementioned disadvantages and which is much more economical in terms of Has facilities.

The invention therefore relates to a method for producing Short length fibrils from sudden relaxation of a two-phase mixture, the molten polymer and solvent contains and is at increased pressure and temperature, by ejection through an opening, so that the Solvent evaporates immediately and the polymer is solidified, with the flow of the two-phase mixture in the Moment is disturbed where it penetrates into the relaxation opening.

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In the description, the term "short-length fibrils" means brilliant, elongated structures, which are formed from very thin filaments with a thickness of the order of microns and one below the other are connected to form a three-dimensional network. Such fibrils with a flaky appearance are generally longer than wider in shape. Your length varies from about 0.5 nim to 5 cm, and their diameter from about 0.01 to 5 ™. The specific surface of such

ο products is very high; it is greater than 1 m / g, and in many

len cases greater than 10 m / g. Such fibrils cease Excellent starting material for the production of non-woven textiles (fleece products) and synthetic ones Papers using normal working methods.

The following is the definition for the term "two-phase mixture, the molten Contains polymer and solvent, "given: If you think of a mixture of polymer and suitable solvent of suitable concentration of polymer which is at a temperature higher than the melting temperature of the polymer if a very high pressure is applied, it is observed that the mixture is in the form of a uniform, homogeneous, liquid Phase is present. If you then keep all other conditions constant the pressure progressively If it is lowered, it is observed that the homogeneous, liquid phase changes from a certain pressure, which varies depending on the case cloudy as a result of the appearance of a system of two liquid phases, the system being characterized by a continuous, polymer-rich phase is formed in which droplets of a liquid, polymer-poor phase are dispersed. The value of the pressure at which this phenomenon occurs can easily be determined experimentally for different values of the

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Temperature and the concentration of polymers! to be determined. To by a sudden relaxation structures of high
To maintain quality, the use of mixtures that are in a two-phase state is recommended.

The polymer or polymers which is / are present in the mixture subjected to the sudden relaxation can be any, as long as they lead to the formation of two-phase mixtures in the presence of suitable solvents.
In general, all polymers which can be spun into threads can be used in the process according to the invention.

Examples are: polyolefins, polyamides, thermoplastics Polyesters, polyurethanes, polycarbonates, vinyl polymers (e.g. polymers based on vinyl chloride, vinyl acetate ' or vinylidene fluoride) and acrylic polymers (e.g. polymers made from Acrylonitrile or methyl acrylate).

However, preference is given to using crystalline polymers whose degree of crystallinity, measured by X-ray diffraction, is above 10% and preferably above 20%. In fact, the stretching process to which the very thin filaments which form the fibrils are subjected to the sudden evaporation of the solvent as a result of the sudden relaxation of the solvent vapors gives them an oriented structure when they are formed from a crystalline polymer, and thus also noticeably better mechanical properties. '

The best results will be with crystalline polyolefins
obtain. Of these, the most commonly used are polymers of substantially linear structure which contain at least 50 mole percent of an alpha-olefin having from 2 to 6 carbon atoms

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contain. Examples are high density polyethylene and isotactic polypropylene, which are very readily available commercially, as are isotactic polybutene- (1 ) and isotactic poly-4-methylpentene- (i), which are, however, produced on a much smaller scale.

With regard to the solvent or solvents used, it is preferred that they do not dissolve ^{the polymer under normal conditions of pressure and temperature (atmospheric pressure, 20 ° C.).} Under such conditions they must not dissolve more than 50 g / l and preferably not more than 10 g / l of polymer.

It is also preferred that their boiling point is lower than the temperature at which the polymer or polymers can be plastically deformed: they should have a boiling point at normal pressure of more than 20 ^° C. and preferably more than 40 ^° C. below the deformation temperature of the polymer or polymers . In addition, they must allow the formation of liquid two-phase mixtures, as previously defined, under the conditions of temperature and pressure which allow the instantaneous evaporation and solidification of the polymer.

For the sake of simplicity, we will use a common Solvent is always preferred when using several different polymers.

Among the numerous solvents that can be used are in particular the aliphatic hydrocarbons such as n-butane, n-pentane, n-hexane and n-octane and their isomers; cycloaliphatic Hydrocarbons such as cyclohexane and methylcyclohexane; aromatic Hydrocarbons such as benzene, toluene and xylene; Alkane halides such as chloromethane, chlorofluoromethane, chloroethane

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and chlorofluoroethanes; Alcohols, ketones, esters, amides, nitriles and called ether.

When employing one or more polymers selected from crystalline polyolefins, the use of one Solvent preferred, that of aliphatic and cycloaliphatic hydrocarbons with 4 to 8 carbon atoms selected, such as B. hexane and cyclohexane technical grade.

In the method according to the invention, it is sufficient to apply the pressure to select the mixture subjected to sudden relaxation so as to that it is in the form of a two-phase mixture. The same applies to the temperature and the concentration of polymers.

In general, it is preferred to work at a temperature between 100 and 300 ° C. and preferably between 125 and 250 ^° C.

The concentration of polymer is generally between 1 and 500 g per kg of the mixture. Mixtures are preferred containing 10 to 300 g of polymer per kg of solvent and particularly preferably 50 to 200 g / kg.

In addition to the polymer and solvent, which like The two-phase mixture can be present as individual substances described above or can itself be formed from mixtures contain common additives for polymers, z. B. Antioxidants, light stabilizers, antistatic agents, surfactants, reinforcing agents, fillers, pigments, dyes and nucleating agents, provided that this does not result in the formation of the mixture, the immediate evaporation of the solvent and the solidification of the polymer affect *

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In the case of sudden relaxation, the pressure of the or the Two-phase mixtures to a value close to atmospheric pressure and preferably to a pressure below 3 kg / cm absolutely in a very short time interval, preferably less than 1 second. This relaxation is going through Passing through a preferably cylindrical opening, the diameter of which is between 0.1 and 3 mm and preferably between 0.5 and 1.5 mm and their ratio length / Diameter between 0.1 and 10 and preferably between 0.5 and 2 is achieved.

If the opening does not have a circular cross-section, the hydraulic diameter must be taken into account as the diameter.

According to the invention, the flow of the two-phase mixture flowing to the entrance of the expansion port becomes immediate before entering it disturbed. Because the continuous, liquid phase of the two-phase mixture is rich in polymer Phase, the two-phase mixture has a very high viscosity. Therefore it is believed that it is under laminar Conditions flowing, with the flow filaments having parallel flow lines exhibit. The perturbation causes the modification of these flow conditions just before the two-phase mixture penetrates into the relaxation opening. Of course, such a disturbance must be carried out under such conditions be that it has not yet been damped by the time the two-phase mixture enters the expansion opening.

According to a preferred embodiment, the flow of the Two-phase mixture disturbed by upstream of the Relaxation port diverted part of the flow of the two-phase mixture subjected to the sudden relaxation and is directed so that this part enters the relief opening in a direction which is at an angle with the axis

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the relaxation opening forms.

Preferably, the angle between the direction of the Part of the river that is most diverted and the Axis of the relaxation opening is formed between 50 and 135 °. The best results are obtained when this angle is between 75 and 120 °. In the simplest form of implementation the angle amounts to 90 °.

This deflection can advantageously be carried out by the two-phase mixture subjected to the sudden relaxation is passed through a disturbance chamber, which opens onto the expansion opening.

According to another embodiment, the flow of the two-phase mixture entering the disturbance chamber is through a feed opening divided into a variety of currents.

This division of the flow of the two-phase mixture can be carried out by the feed openings of the disturbance chamber by interposing a piece for flow division or a grid, preferably a metal mesh, in which of the trajectory followed by the flow.

If a metal mesh is used, this can e.g. B. be arranged above the feed opening of the disturbance chamber, d. H. against the area upstream of the partition into which this feed opening is drilled. However, it is preferred according to the invention that the metal mesh is arranged in the disturbance chamber is, preferably against the partition carrying the feed opening. The metal mesh should preferably be arranged so, that it is perpendicular to the direction of flow of the two-phase mixture.

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The metal mesh must have a mesh size of at least 0.1 mm, so that any risk of contamination or possibly clogging is avoided.

The dimension of the mesh of the metal mesh can be the dimension reach the feed opening and even exceed this value, provided that at least one of the threads forming it is straight to the Feed opening is located, d. H. on the trajectory followed by the flow of the two-phase mixture.

You can also divide the flow of the two-phase mixture bring about by the interference chamber is supplied through a plurality of feed openings, these openings are drilled into the partition, which closes the disturbance chamber upstream. The axes of such openings can be parallel to each other or be inclined with respect to other axes.

Of course, these two embodiments can be combined, and one can advantageously use the interference chamber Feed through several openings and also provide this chamber with a metal mesh.

It can be important that the exit of the relief opening diverges in order to channel and guide the short fibrils emerging from this opening. It was found, however, that it is sufficient if this diverging angle is at least 150.

It has also been found that the two-phase mixture is preferred enters the interference chamber through an opening or openings whose angle formed by the entry walls at most is equal to 30 or at least equal to 150.

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The previously tesch rubbed methods allow the direct and economic production of Fihrillen of short length, which is often associated with the undesirable formation of a ^v relatively large number of platelets, which are small, dense particles with the structure of a film or skin, the largest Dimension can now reach and exceed 0.5.

The. Presence of these platelets in the short fibrils are found in the later use of such fibrils for the production of synthetic papers as annoying. Indeed, it has been observed that these platelets are difficult to remove and, in general, that they settle can be found in the papers produced in the form of transparent dots or impurities that reduce the transparency affect the end products.

However, it is possible that the formation of platelets is essential reduce and even completely suppress by the wall of the relaxation opening with the help of a film one with lubricant that is incompatible with the two-phase mixture.

In a realization of this embodiment according to the invention you can the walls of the expansion opening with a thin skin of a suitable lubricant such as B. cover a silicone.

However, the improvement found in this case in terms of the reduction in the number of platelets is noticeable not permanent. It was found that the number of formed Platelets, which are noticeably diminished when starting up gradually increases again over the course of the operating time.

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Therefore, according to a preferred embodiment, this Lubrication of the walls of the relief opening by continuously flowing a film of a liquid, with the two-phase mixture formed at the inlet of the expansion opening non-compatible lubricant ensured.

Working in this way, it has been found that reducing the number of platelets formed or suppressing them is maintained permanently.

The liquid lubricant used in this embodiment of the method can be any lubricant, if it is not compatible with the two-phase mixture, i.e. a continuous phase separate from this mixture forms, and in particular does not dissolve in the polymer present in the mixture. Such a lubricant is preferred brought to a temperature close to the temperature of the two-phase mixture before it hits the wall of the expansion opening is directed.

However, for the sake of simplicity and economy, it is preferred that the lubricant used be optional is water containing a wetting agent. Such a type of lubricant actually enables it to be achieved excellent results. In addition, the short fibrils thus formed become very easily suspended in the water transferred even if the polymer making them up is hydrophobic. Eventually the water evaporates as the fibrils are made to form a skin that traps the fibril flow and prevents them from sticking to the warm parts of the expansion nozzle.

The liquid lubricant is introduced at a rate of between 30 and 250 l / h and preferably between 40 and

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150 l / h, if the special devices described below are used, the expansion opening of which has a diameter in the range of Λ mm.

In order to carry out the method according to the invention, were various devices of particular type have been developed which also form part of the invention.

These devices or spinnerets differ mainly of the already known devices in that they comprise an interference chamber which has at least one feed opening and a relief opening opposite it, on v / iron *

In the simplest embodiment, the feed opening, which is also cylindrical, and the expansion opening coaxial with one another, and the disturbance chamber has a rotational symmetry around their common axis.

According to a first embodiment, the interference chamber can with be equipped with a metal mesh or be supplied by a large number of feed-in ovens.

According to a second embodiment, the interference chamber from a second circumferential chamber connected to a source of liquid lubricant and opens into the interference chamber through a circular slot that the Entrance of the relaxation opening surrounds. That way stands the peripheral chamber communicates with the disturbance chamber so that a film of the liquid lubricant is continuous is directed onto the wall of the relaxation opening.

The devices according to the invention are described in more detail below described in detail with reference to the drawing. In the

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Figures of the drawing are schematically different in section Embodiments shown. In detail are:

1 shows a view of a complete device which is used for carrying out the method according to the invention suitable is;

FIGS. 2 to 7 embodiments of the end part of the device according to FIG. 1;

8 shows an embodiment which consists of several, arranged in series Disturbance chambers served;

Fig. 9 is a view of a device in which a metal fabric is used;

10 shows a view of a two feed openings Contraption;

11 shows a sectional view along the axis AA ¹ of FIG. 10;

Fig. 12 is a view of another embodiment of the device according to FIG. 10;

13 is a view of another embodiment of one according to the invention Spinning device, which d i ·: formation of a continuous lubricant film; in the amount of Wall of the Enb tension opening allows.

As can be seen from FIGS. 1 to 7, the invention includes; -; - according to Spinning device has a relaxation opening 2 and a pre-relaxation device. This pre-relaxation device, which, according to the embodiment shown, is formed by a partition 3 having a central opening 4, however, it is by no means essential. Its purpose is to

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a loss of pressure in the mixture of molten polymer em and to bring about solvent, which is in the form of a single-phase, the spinning device traversing liquid is located to cause the formation of a two-phase mixture.

This procedure has certain advantages: On the one hand it is easier to make a single-phase mixture and, on the other hand, the quality of the two-phase mixture is more constant

However, this device can be omitted in the case where the spinning device is directly connected to a two-phase mixture is fed from polymer and solvent.

The spinning device also includes a disturbance chamber 5 »which in particular by the wall carrying the expansion opening 2 and by a flat, upper wall 6, which is the feed opening 7 in its central point is limited. The feed Relaxation ports are opposite and coaxial. The disturbance chamber is cylindrical with a circular cross-section. The openings cover the centers of the bases. The distance between the openings (height) is generally less than 10 cm and preferably less than 75 cm. more details with regard to such a chamber are specified below.

As can be seen from FIGS. 2 to 7, the inlet and the exit of the relief opening 2 different profiles own.

When the chamber 8 of the spinning device by a two-phase mixture is fed from molten polymer and solvent, this mixture flows because of the in-line alignment the opening 7 of the wall 6 and the relaxation opening

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through the disturbance chamber with a preferred, central flow thread 9 and with lateral threads 10, which are directed in the vicinity of the relaxation opening 2 in relation to the central thread in the transverse direction through the walls of the disturbance chamber. The angle of incidence of these lateral threads can be varied by modifying the profile of the wall carrying the relaxation opening 2, as can be seen from FIGS. It can be seen that the angle formed between the axis of the expansion opening and the wall of the chamber in which this opening is drilled determines the angle of incidence of the most eccentric lateral flow threads which are most strongly deflected. This angle is preferably between 30 and 135 °, with the best results being obtained when it is between 75 and 120 °. In the simplest embodiments, Fig. 1, 3, 4-, 7 and 8, it is 90 °. In addition, it may also be advantageous to provide 5 ^m i 't a profile the interfering bunting, z. B. by suppressing dead angles as .This particular from FIG. 7 is visible, so that the paths of the side, most deflected flow threads which run near the wall always form a tangent with this wall.In such a case the speed of the part of the flow which is deflected the most is maximum.

Furthermore, it can be advantageous to use a spinning device as shown in FIG. 8, in which various interfering chambers 5 arranged in series are provided.

In addition, it is desirable that the interference chamber satisfies the various criteria for the performance to bring an optimum.

So it is obviously sufficient if the interference chamber is sufficient Has transverse dimension to the formation of the lateral

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To obtain flow threads that the central flow thread at the level of the entrance of the relaxation opening 2 to can disturb.

For a similar reason, it is also advantageous if the distance between the openings of the interference chamber (height of the Chamber) is also larger than the diameter of the feed opening. It is obvious that if the height is too low of the perturbation chamber, the deflected lateral flow filaments are not effectively transverse to the central one Flow filament can be directed. If, on the other hand, the height of the interference chamber is too great, the deflected, transversal ones have Flow thread the tendency to reunite with the central flow thread and parallel to it before they reach the relaxation opening. It has been found that the height that the disturbance chamber can have depends on the diameter of this chamber. LTm a maximum To achieve effectiveness, it is necessary that the ratio between the height of this chamber (distance between the openings) and their lateral dimension below 5 and preferably is below 5.

Furthermore, it has been found that the diameter of the feed opening is preferably at least equal to half the diameter the relaxation opening is.

As can be seen from FIG. 9, the spinning device 1 can be provided with a metal fabric 12 for sudden relaxation which is arranged in the disturbance chamber 5. This interference chamber 5 is' in particular through the expansion opening 2 load-bearing wall and an upper, flat wall 6, which carries a feed opening 7 in its center. the The expansion opening 2 and the feed opening 7 are in the particular case opposite one another and coaxial with one another. the

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Side wall of the interference chamber 5> which is cylindrical, is through a circular ring 13 is limited. It should be pointed out, however, that the interference chamber 5 can have a different shape, in particular a parallelepiped shape. The function of the circular ring 13 is twofold: On the one hand, this ring limits the Height of the interference chamber 5 and on the other hand it holds the tissue 12 with fine mesh, which is arranged in the disturbance chamber against the wall 6 having the feed opening, in its Location.

The spinning devices shown in Figs. 10, 11 and 12 are of the same type as those shown in Fig. 9, only that they have no metal mesh arranged in the disturbance chamber. In addition, the connection between the feed chamber 8 and the disturbance chamber 5 ensured by two feed openings 7, the axes of which are inclined to one another and which is located in a single opening on the side of the feed chamber unite. In these spinning devices or spinnerets, the circular ring 13i serves as the cylindrical side wall limited to the interference chamber, only to regulate the height of this chamber.

As already described, the spinning devices shown in FIGS. 10, 11 and also with a Metal mesh, which is attached in its disturbance chamber, and / or with two or more openings, their axes are parallel to each other.

As can be seen in particular from FIGS. 1, 2, 3? Gives 4, 8 and 12, you can provide a diverging course at the exit of the relaxation opening, the angle of this diverging piece is preferably above 150.

Finally, as can be seen from FIG. 13, the spinning device 1, a pre-expansion chamber 8, a feed opening 7 for the disturbance chamber · 5 and an expansion opening 2, still with one located on the circumference

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Chamber 15 be provided which surrounds the disturbance chamber 5, wherein the partition 14 separating these chambers is interrupted at the level of the entry of the expansion opening 2, that an annular slot 17 coaxial with the expansion opening is formed. The chamber located on the circumference 15 is also equipped with a connection 16, in order to be able to put them in contact with a source of a liquid lubricant.

The method according to the invention is explained in more detail below on the basis of the practical exemplary embodiments.

example 1

A two-phase mixture was prepared in which a mixture containing 15% by weight of high-density polyethylene with a melt index of 5 (trade name Eltex A 1050, the applicant's product) and 85% by weight of technical grade hexane was heated to 195 ° ^C. and a pressure of 63 kg / cm ^ was brought. These conditions correspond to the beginning of the appearance of two liquid phases.

This mixture is made by passing it through a spinning device with interference chamber, as in the Pig. 4 of the drawing is described, relaxed, this interference chamber following has geometric properties:

- Ratio between the diameter of the disturbance chamber and the diameter of the feed opening 7 = 16;

- Relationship between the height of the disturbance chamber and the diameter the feed opening 7 = 5>

- Relationship between the height of the disturbance chamber and the diameter this chamber = 0.313 »

- Diameter and height of the feed opening 7 and the expansion opening = 1 mm.

The lengthening the opening for the sudden relaxation, diverging section had an opening with an angle of 150 °.

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The two-phase mixture was in an amount of 21.4 kg Polymerem enforced per hour.

Short fibrils with a medium length were obtained directly of 1.7 mm · The specific surface area of these fibrils amounted to to 35 m / g.

Example 2

The procedure of Example 1 was repeated, except that the mixture was previously subjected to a preliminary relaxation of 12 kg / cm would have. Short fibrils were also obtained with a mean length of 1.9 mm.

The specific surface area of the product was 23 m ² / g.

Example 3

The procedure of Example 2 was repeated, except that the spinning device had the following modified geometrical properties:

- Ratio between the height of the disturbance chamber and the diameter of the feed opening 7 = 200;

- Ratio between the height of the disturbance chamber and the diameter of this chamber = 12.5

A continuous, brilliant lock was obtained.

This negative result is likely due to the fact that the interference chamber has too great a height in relation to its diameter.

Example 4

The procedure of Example 2 was repeated, but using a spinning device with a disturbance chamber as shown in FIG is used, their geometric properties

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245839Q '

identical to that of Example 1.

There were short fibrils with an average length of 1.8 mm obtain.

The specific surface was 21 m / g.

Example 5

The procedure of Example 4- was repeated, except that the spinning equipment was modified as follows, geometrical
Features:

- Ratio between the height of the interference chamber and the diameter of the feed opening 7 = 4-0;

- Ratio between the height of the disturbance chamber and the diameter of this chamber = 2.5

Short fibrils with an average length of 2.3 mm and a specific surface area of 26 m / g were again obtained
belief.

Example 6

The procedure of Example 2 was repeated, but using a spinning device as shown in FIG.
was used, the geometric properties of which are as follows
was: ,

- Ratio between the diameter of the disturbance chamber and the diameter of the feed opening 7 = 6 »

- Relationship between the height of the disturbance chamber and the diameter of the feed opening 7 = 3 »

- Ratio between the height of the interference chamber and the diameter of this chamber = 0.5 »

- Diameter and height of the feed opening 7 and the expansion opening = 1 mm.

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The result was short fibrils with a specific surface area by JO

belief.

2
obtained from JO m / g, the mean length of which is 2.1 mm

Example 7

The procedure of Example 2 was repeated, but using the expansion spinneret with a diverging section was equipped with an opening of 150.

Furthermore .wurden the geometric properties of the spinning device modified as follows:

- Ratio between the diameter of the interference chamber and the diameter of the feed opening 7 = 13> 3>

- Ratio between the height of the disturbance chamber and the diameter of the feed opening 7 = 4.16;

- ratio between the height of the interference chamber and the diameter of this chamber = 0.313;

- Diameter of the feed opening 7 and the relaxation opening = 1.2 mm;

- Height of the feed opening 7 and the expansion opening = 1 mm.

The mass flow rate of polymer was found to be 30 kg / h achieved. Furthermore, short fibrils with an average length of 2.2 mm were obtained.

The specific surface was 30 m / g.

Example 8

The procedure of the previous example was repeated, but with the geometric properties of the spinning device were changed as follows:

- Ratio between the diameter of the interference chamber and the diameter of the feed opening 7 = 10.7 »

- Ratio between the height of the disturbance chamber and the diameter of the feed opening 7 * 3 * 34-;

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- Diameter of the feed opening 7 and the expansion opening = 1.5 mi;

- Height of the feed opening 7 and the expansion opening = 1 mm.

It has been found that the mass flow rate of polymer 49 kg / h is reached and that one short fibrils with a medium one Length of 2.6 mm.

The specific surface area was 23 m / g.

Example 9

The procedure of the previous example was repeated, but using a spinning device of that shown in FIG Type was used, which therefore comprised three disturbance chambers arranged in series.

The diameter of the successive openings in the The direction of flow of the two-phase mixture were 2 mm, 1.5 mm, 1-2 mm and 1 mm, respectively. The diverging section possessed an opening of 150 °.

Short fibrils with an average length of 1.9 mm were obtained, the specific surface area of which was 10 m / g.

Example 10

It was a mixture containing 10 wt .-% of a polypropylene with a melt index of 2.9 (trade name Profax 6501 from Hercules Powder Co.) and 90 wt .-% technical pentane, at a temperature of 195 ⁰ O and at one pressure

of 83 kg / cm.

This mixture was made by passing it through a spinner with interference chamber, which was equipped with a metal grid as shown in Fig. 9 and the following geometric Features, relaxed: -

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- Ratio between the diameter of the disturbance chamber 5 the diameter of the feed opening 7 = 6 5

- Relationship between the height of the disturbance chamber and the diameter the feed opening 7 = 2;

- ratio between the height of the disturbance chamber and the diameter of this chamber = 0.333;

- Diameter and heights of the feed opening 7 = 1 stroke

- Diameter and height of the relief opening 2 = 1.1 mm and 1 mm, respectively.

In addition, the metal mesh had 12 square meshes with a dimension of 0.4 mm.

At the moment of penetration into the feed chamber 8, the mixture of polymers! and solvent with a pre-relaxation of 3 k
to convert.

tion of 3 kg / cm to make it a two-phase mixture

The two-phase mixture was passed through the expansion opening 2 i-n in an amount of 10.3 kg of polymer per hour.

Short fibrils of medium length became straight away of 1.7 now received. The specific surface area of this short

Fibrils amounted to 3 πι / g.

Example 11

The mixture prepared according to Example 10 was passed through a spinning device with a disturbance chamber, such as shown in Figs. 10 and 11 of the drawing, relaxed, which had the following properties:

The interference chamber 5 had a height of 2 mm and a diameter of 4 mm.

The relaxation spinning nozzle 2 had a height and a diameter of 1 mm.

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The connection between the feed chamber 8 and the disturbance chamber 5 was secured by two openings with a diameter of 0.8 mm and a length of 1.4-3 mm, whereby the axes of the "two openings each make an angle of 4-5 formed with the longitudinal axis of the spinneret.

At the moment of penetration into the feed chamber 8, the mixture of molten polymer and solvent had a preliminary relaxation of 3 kg / <
Convert two-phase mixture.

subjected to a pre-relaxation of 3 kg / cm to turn it into a

The two-phase mixture was released through the expansion opening 2 sent through with an amount of 13.9 kg of polymer per hour.

Short fibrils with an average length of 1.9 mm were obtained directly. The specific surface area of these short fibrils was 3 m ² / g. '

Example 12

The mixture prepared according to Example 10 was relaxed by being passed through a spinning device with a disturbance chamber _y as shown in FIG. 12 of the drawing.

This spinning device had identical properties to that Spinning device shown in FIGS. 10 and 11 and used in the example, however, the expansion spinning nozzle 2 being limited by a cutting edge (height zero), and was provided with a deflector 11, one of which is diverging Possessed angle of 150 °.

At the moment of penetration into the feed chamber 8 was the mixture of molten polymer and solvent

a pre-relaxation of 3 kg / cm - subjected to it in a

5 0 9 8 3 0/0 8 3 6

Convert two-phase mixture.

The two-phase mixture was released through the expansion port 12 sent through in an amount of 14, 3 kg of polymer per hour.

Short fibrils of medium length became straight away of 1.2 mm. The specific surface of this short

Fibrils amounted to 3 m / g.

Example 13

There was prepared a mixture comprising 85 wt -.% Technical-grade hexane and 15 wt. - (. Warenbezei '· liming Eltex A 1050)% of the polyethylene described in Example 1, and T, 5 wt .-% calcium stearate containing included, and this mixture was heated to a temperature of 194 · ⁰ C and brought a pressure of 66 kg / cm.

This mixture was made by passing it through a spinneret with disturbance chamber, as shown in Fig. 13, relaxed, this having the following properties:

- Ratio between the diameter of the Störkanimer 5 and the diameter the feed opening 7 = 16;

- Ratio between the height of the interference chamber 5 and the Diameter of the feed opening 7 = 3 »

- Ratio between the height of the Störkanimer 5 and the Diameter of this chamber = 0.187 »

- Diameter and heights of the feed opening and the iMitspari · - opening - 1 mm.

At the moment of penetration into the feed chamber B was the mixture of polymer and solvent of a Vorencspan-

tion of 3 kg / cm to put it in a two-phase chamber to convert.

S09830 / U836
ORIGINAL INSPECTED

During the relaxation, water at 195 ° ^{C. was} injected via connection 16 under a pressure of 44 kg / cm with a throughput of 95 l / h.

The two-phase mixture was in an amount of 14.4 kg of polymer em per h prevailed.

Short fibrils of medium length became straight away
of 2.3 mm. These fibrils were free from platelets.

When the injection of water was stopped, rose
the throughput of the mixture to 16.4 kg of polymer! per hour. The fibrils produced were then of medium length
of 1.9 nim, and their manufacture was accompanied by the formation of platelets. That from the last described
Synthetic paper made fibrils had a
Inspection indicating damage, as the presence
one
became.

ο
a mean value of 9 large platelets per dm was found

Also included fibrils made using a device, the one with four curved ones
and profiled feed openings provided disturbance chamber, so that the two-phase mixture introduced into the disturbance chamber at an angle of approximately 45 ° with the axis
the direction forming the expansion opening (Lechler KS 11 atomizer) also had a substantial number of platelets.

50 9 830/0836

Claims (1)

Claims Process for the production of short-length fibrils by sudden relaxation of a two-phase mixture, which contains a molten polymer and solvent and is at elevated pressure and temperature, by ejection through an opening with immediate evaporation of the solvent and solidification of the polymer, characterized in that the Flow of the two-phase mixture is disturbed at the moment when it is in
the relaxation opening occurs. 2. The method according to claim 1, characterized in that the flow of the two-phase mixture is disturbed by diverting a portion of the flow, this being so directed
becomes that it enters the relief port in a direction which forms an angle with the axis of the relief port. 5. The method according to claim 2, characterized in that the between the direction of the portion of the flow that is diverted is, and the axis of the relaxation opening formed angle between 30 ° and 135 °. 4. The method according to claim 2, characterized in that the part of the flow which is most strongly deflected,
is directed according to a trajectory that you
able to give maximum speed. 5. The method according to claim 1, characterized in that the The flow of the two-phase mixture is disturbed by introducing it into a disturbance chamber which opens into the expansion opening will. 509830/0836 6. The method according to claim 5 »characterized in that the Disturbance chamber has a feed opening opposite the expansion opening lies. 7. The method according to claim 6, characterized in that the distance between the feed opening and the expansion opening is below five times the transverse dimension of the
Disturbance chamber lies. 8. The method according to claim 5 »characterized in that the Disturbance chamber is profiled in such a way that the path in the vicinity of the wall forms a tangent to this at every point. 9. The method according to claim 5 *, characterized in that
several disturbance chambers -are arranged in series and over
Openings are in communication. 10. The method according to claim 5 »characterized in that the axis of the relaxation opening and the wall of the disturbance chamber in which this opening is drilled, one with the other
Form angles between 30 and 135 °. 11. The method according to claim 6, characterized in that the distance between the feed opening and the expansion opening is greater than the diameter of the feed opening
is. 12. The method according to claim 6, characterized in that the diameter of the feed opening is at least equal to the
Half of the diameter of the relaxation opening is. 13. The method according to claim 6, characterized in that the The feed opening and the expansion opening are coaxial with one another. 509830/0836 . 24Γ) 83ϋϋ 14-. Method according to claim 13, characterized in that the disturbance chamber has a rotational symmetry about the axis of the feed opening and the expansion opening. 15. The method according to claim 5j, characterized in that der.Fluß of the two-phase mixture penetrating into the disturbance chamber divided into a variety of currents. 16. The method according to claim 15, characterized in that the division of the flow or the flow of the two-phase mixture by passing it through an in the interference chamber arranged grid is achieved. 17. The method according to claim 15, characterized in that the division of the flow or the flow of the two-phase mixture is achieved by the disturbance chamber through a large number of feed openings is supplied. 18. The method according to claim 5, characterized in that the two-phase mixture enters the interfering bunting by at least one feed port, wherein the inlet formed by the walls angle above is below 30 ° or I50 ^0th 19. The method according to claim 5 »characterized in that the outer end of the expansion opening is ^{extended by a diverging section, the angle of which is at least equal to I50 0.} 20. The method according to claim 1, characterized in that the walls of the relaxation opening with the help of a A film of a lubricant that is incompatible with the two-phase mixture, lubricates. 509830/0 8 36 ■ - 31 .. 21. The method according to claim 20, characterized in that one the wall of the relaxation opening by continuous Formation of a film of a liquid, with the two-phase mixture incompatible lubricant lubricates at the entrance of this opening. 22. The method according to claim 21, characterized in that the liquid lubricant is water. ? 3 · Method according to claim 21, characterized in that the liquid lubricant is water containing a wetting agent. 24. The method according to claim 21, characterized in that the liquid lubricant is introduced with a flow rate between 30 l / h and 250 l / h. 25 device for carrying out the method according to claim 6, characterized in that it comprises a disturbance chamber which has at least one feed opening and an expansion opening opposite thereto. 26. The device according to claim 25, characterized in that the interference chamber is equipped with a grid. 2? · Device according to claim 25 »characterized in that the interference chamber is equipped with a large number of feed openings. 28. The device according to claim 25, characterized in that the disturbance chamber is surrounded by a second, circumferential chamber which is provided with a source of liquid Lubricant is connected, where it opens into the disturbance chamber through an annular slot, which is the entrance surrounding the relaxation opening. 509830/0836