ES2829173A1 - DEFIBRATING PROCEDURE AND DEVICE TO OBTAIN NANOCELLULOSE (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Defibration procedure to obtain nanocellulose and device to obtain nanocellulose, where the procedure consists of (i) a first stage in which a bleached cellulose solution diluted in water is subjected to pressure in a chamber, (ii) a second stage in the that the solution is passed through a nozzle that has a frusto-conical inlet in which there is a strong acceleration and defibration, a cylindrical passage in which the speed and friction of the solution increase, producing a second defibration, and a frusto-conical outlet arranged inversely to entry, where decompression occurs; (iii) and finally a third stage in which the solution is precipitated into a reception chamber in which collision occurs with the walls thereof and with a shock dead center, producing the third defibration. (Machine-translation by Google Translate, not legally binding)

Description

DESCRIPTION

DEFIBRATING PROCEDURE AND DEVICE

TO OBTAIN NANOCELLULOSE

Technique field

The object of the present invention belongs to the sector of obtaining nanocellulose. It is a process for obtaining nanocellulose by defibration by the combination of pressure, friction, turbulence, acceleration, speed, decompression, expansion and shock of the cellulose. This being a mechanical process route, it is still an efficient alternative to what is known to date, to obtain nanocellulose, proposing a procedure that, starting from a very homogeneous cellulose solution in proportions between 1% and 6% and the The rest of the water is subjected to high pressure to then pass through a characteristic nozzle, in which the solution is subjected to a great acceleration to reach a high speed (turbulent regime), which in turn causes strong friction and turbulence at the outlet of the nozzle, producing the corresponding expansion and decompression as well as the impact of the fluid at high speed in such a way that, with said procedure, the nanocellulose is obtained. Nanocellulose whose fibers in turn have a homogeneous structure and elongated fiber, nano size that, once separated from the water in which it was diluted, by means of a centrifugation process, the nanocellulose is obtained to be used according to interest.

Background of the invention

At present, two manufacturers of said nanocellulose are known, producing it also mechanically, such as:

A) The company MASUKO SANGYO Co. Ltd, which uses a mill pulverization technique, that is, friction grinding by a mechanical grinding process that produces high friction in cellulosic fibers to decrease its size causing the dulling of the material at its exit and difficulties in repeatability in the results obtained. This process forces the solution to be excessively diluted in advance to reduce its size. in addition to requiring a lot of time in the operation, which makes it inefficient, the fibers having to be passed many times until obtaining nanocellulose, with the high energy cost per kilogram of obtaining nanocellulose. This one, although expensive and slow, has several patents. As an example we point to the last mill, JP2019037948, however, they do not even specify in any of their patents that the purpose is to obtain nanocellulose, but rather to grind materials.

B) GEA NIRO SOAVI, use a system that is based on introducing cellulosic fibers in dilution through a small cavity where a piston causes the cavity to close, increasing the pressure in them, reducing the size of the fiber. It turns out that, the passage of the fibers through the cavity, causes an easy dulling of the machine with continuous stops and disassemblies to clean and resume the processing, not being able to work with high-density fiber suspensions, conditioning the use and making this machine Obtain results much lower than those obtained with both our invention and the solution indicated in point A). As an example we can refer to their patents: CN102575751 for "High pressure homogenizer with an epicyclic reduction gear unit", or US2010296363 on a "Homogenizing valve"

There are other chemical ways and procedures for obtaining nanocellulose, however, they are not concurrent with the present invention, giving rise to other types of circumstances and obtaining, which, although they have been studied continuously, have nothing to do with the processes used object of the present invention to obtain it.

The process of the present invention is an evolution of the existing mechanical ways, turning out to be much more efficient and therefore with significant energy savings to obtain it and a high degree of results with repeatability without generating any type of waste, taking advantage of 100% of the treated material.

Nanocellulose is produced after the reduction of cellulose fibers to the nanoscale. In order to reach a scale of between 50 and 100 nanometers, it is necessary to reduce the original fiber to a great extent, a reduction that is not carried out efficiently with the currently known procedures and machines, such as those previously described.

The proposal of this invention to achieve this solution is to use a new mechanical procedure that will make the cellulose solution pass through a first compression stage, to then be passed through a small hole arranged in the piece that acts as an extrusion head and which we will call "nozzle" because it has the characteristics of the passage with angled inlet and outlet and a cylindrical central part, resulting in the cellulose solution in this stage of the process beginning its strong defibration.

Passing through said nozzle causes: a strong acceleration in the solution, which produces a high speed of the solution with significant friction and strong turbulence. All this together with the pressure with which it is introduced into the nozzle (Venturi effect) and the significant friction with the walls of the nozzle produces a combined shredding mechanism. The solution then passes to the next exit stage with a strong depression and consequent expansion, together with a great inertia due to the significant velocity acquired to produce a final impact of said solution, both against the walls of the exit chamber, as well as with a front dead center output. All this process produces the obtaining of nanocellulose (fibers between 50 and 100nm), whose fibers also have an elongated and spun fibrous structure, characteristics that result in a novel raw material, which opens a wide range of applications and opportunities very efficient in multiple sectors.

Presentation of the invention

The process object of the present invention is characterized by comprising several stages by which cellulose is converted into nanocellulose and is thus arranged:

1. - A preliminary and optional stage that can refine and perfect the main stages of the process object of the invention, being a recommended preliminary stage for the good result of the product, increasing its performance and efficiency. In this previous stage, the raw material (bleached cellulose) is subjected to a mixing process by beating in a conventional device, so that a very homogeneous starting solution is obtained, avoiding the cutting of the fibers and facilitating the process to be carried out. later in the other stages. This preliminary consists of diluting the bleached cellulose in water, without any other component, in the desired consistency, leaving the preparation of the diluted cellulose solution, in a proportion of between 1% and 6%, at rest about 12 and 24 hours to later subject it to a shake of between 7,000 to 12,000 revolutions per minute (rpm).

2. - An initial stage in which the cellulose diluted in water is subjected to a pressure of between 250 and 600 bars in a main working chamber. This is where the cellulose solution is homogenized in various concentrations between 1% and 6%, which entails the need to resort to parts specially designed to withstand these pressures, in order to ensure the efficiency of the process. and directing the compressed solution to the nozzle.

3. - A central stage, which turns out to be the most novel and original for using in the process an innovative defibration of the cellulose diluted in water (in a proportion of between 1% and 6% and subjected to a pressure of between 250 and 600 bars), at this stage the solution is passed through the nozzle which, having a frusto-conical inlet to facilitate the entry and guidance of the solution to its central cylindrical passage with a very strong acceleration (when acquiring a high velocity of the passage of the fluid that can oscillate between 50 meters / second, to 250 meters / second), the combination of strong friction on the nozzle passage walls with the consequent turbulence in the solution which, together with the great pressure that it carries, causing the most important mechanism for the pulping of the cellulose obtaining an important part of the nanocellulose total at this central stage of the procedure. This arrangement and this stage already makes it possible to obtain the different qualities of microfibers and nanofibers, all in combination of the pressure to which the solution is subjected and the use of the nozzle that is used in addition to the size of the central cylindrical passage zone. This can vary between a diameter of 0.2 millimeters to 2 millimeters and a length of between 3 and 100 millimeters, in combination of the sizes that can be made to the inlets and outlets of the nozzle and its frusto-conical shapes practiced to the effect, since its angles and depth can vary depending on the entry attack that best suits.

4.- A final stage of exit from the nozzle towards a chamber for collecting the solution with the cellulose in part already transformed into nanocellulose. However, it is in the final stage, at the nozzle outlet itself, where the shredding is complemented by subjecting the solution to a very strong expansion due to the free decompression of the solution, or even aided by another decompression also added from among them. 250 and 600 bars in the main chamber but negative in the collection chamber itself. This coupled with the speed with which the solution exits the nozzle, in turn produces a strong impact against the walls of the collection chamber and, very particularly, its front dead center of exit placed between 15 and 150 millimeters (mobile or immobile), since the solution carries a great speed and inertia.

With all these stages to which the solution is subjected, cellulose micro and nanofibers are obtained that depending on the needs and destinations of the same, one device or another can be used but it will always have a passage through the nozzle , reproducing the procedure as many times as is considered appropriate, as well as with as many nozzle sizes as appropriate in combination with the different pressures to achieve that the nanocellulose can be obtained with a greater or lesser crystallization character or transparency. All this together with a better quality to reach a scale of between 50 and 100 nanometers, reducing the original fiber to a great extent with great homogeneity.

Each of the stages has been optimized within the different options provided. In the initial stage of feeding the cellulose and in the intermediate defibration stage, different techniques and materials have been tested, adjusted to the dynamic behavior of the microfibers. As a result of all this, it has been observed that it is necessary to adjust the different parameters of the arrangement used in each case: a) proportions of the dissolution of the solution with water of between 1% and 6% cellulose, beating the whole and letting it rest for between 12 and 24 hours to proceed to a new beating of between 7,000 and 12,000 revolutions per minute; in combination with b) subjecting the solution in a chamber to a pressure of between 250 and 600 bars; in combination with c) having a nozzle to pass the solution through it, having a central size with a diameter between 0.2 and 2 millimeters and a length between 3 and 100 millimeters; to finally pass to a reception chamber where the solution is subjected to an expansion with a decompression that can even be increased, which can range between 250 and 600 negative bars depending on the geometry of the nozzle (Venturi effect and fluid dynamics ) and the collision with the neutral point that can be located more or less close to the outlet of the nozzle, between 15 and 150 mm, this being able to be mobile.

In the procedure, due to the use of liquid solutions, the device is subject to the laws of fluid thermodynamics, being subject to significant friction and change of state of the solution with the corresponding energy transformations causing heat release ( due to the very high friction with the walls of the nozzle), which will lead to complementing both the chambers and the nozzle itself with the corresponding cooling arrangements, to withstand temperature changes with high pressures, friction, turbulence, speeds , etc. that occur particularly in the interior of the nozzle and in the passage of the solution through its interior with the important defibration in said step.

Brief description of the drawings

Next, by means of the drawings, the different stages of the procedure, parts and arrangements of the device for defibrating and obtaining the nanocellulose object of the invention are explained, complementing the specification, illustrating the preferred example, helping to better understand the invention , consisting precisely of an embodiment of said invention, but in no way limiting it.

The above and other characteristics and advantages will be more fully understood from the following detailed description of an embodiment with reference to the drawings of the attached figures, in which:

Figure 1 shows a view of the device with the nozzle in combination with the compression and inlet chambers, with the decompression and solution reception chambers, with its shock dead center and the solution compression and pushing device.

Figure 2 shows a view of the nozzle and its frusto-conical inlet and outlet parts and its cylindrical central passage.

Figure 3 shows a view of the nozzle at the time of passage of the solution, for all its parts.

Figure 4 shows a view of the solution and its passage through the nozzle, indicating the friction, speed, turbulence, and when exiting the nozzle, decompression and expansion occur in combination with the shock in the receiving chamber and its neutral point.

Figure 5 shows a view of the device in its similar assembly in full operation with the entry, passage and exit of the solution subjected to the steps of the process object of the present invention.

Figure 6 shows a view of the method in which the functions of P = pressure are represented; V = speed; R = Friction; T = Turbulence and E = Expansion with Shock.

Description of the different elements of the invention

1. - Cellulose solution diluted in water in a proportion of 1% to 6%.

2. - Compression chamber for solution 1, which faces the inlet of the nozzle (3) and has the compressor and thrust (12)

3. - Nozzle that has a passage (4) for the solution (1), which is in combination with the compression chamber (2) on one side and on the other with the reception chamber (7)

4. - Cylindrical tubular passage that has the nozzle through which the solution passes (1) causing strong turbulence (T), with friction (R) and at high speed (V), and which is limited at its ends by the corresponding inlet frustoconical (5) and outlet in the same way frustoconical (6).

5. - Truncated cone inlet of the nozzle (3).

6. - Truncated cone outlet of the nozzle (3).

7. - Chamber for receiving the solution (1)

8. - Neutral point of the reception chamber (7) where the solution (1) collides. 9. - Wall of the frusto-conical inlet (5) where the solution rubs (1)

10. - Perimeter wall of the passage (4) of the nozzle (3) where the solution (1) rubs.

11. - Wall of the frusto-conical outlet (6) where the solution (1) rubs.

12. - Compressor device of the compression chamber (1) and that also directs the solution towards the nozzle (4).

13. - Decompressor device of the reception chamber (7), to increase the expansion of the solution (1).

14. - Cooling device.

E.- Expansion of the solution (1) in the reception chamber (7) by decompression.

P.- Pressure on the solution (1) in the compression chamber (2) with the compressor (12)

R.- Friction of the solution (1) that occurs on the frustoconical inlet and outlet walls (9) and (11), as well as on the wall of the passage (4) of the nozzle (3).

T.- Turbulence of the solution (1) as it passes through the nozzle (3) through its passage (4) and the frusto-conical inlets and outlets (5) and (6).

V.- Speed reached by the solution (1) of between 50 m / s and 250 m / s.

Detailed description of the realization example

The attached figures show the preferred embodiment of the stripping procedure and arrangement to obtain nanocellulose object of the present invention, consisting of the following:

1 ° .- As a previous and optional stage or embodiment is to obtain a solution (1) which, using a bleached cellulose raw material, it is subjected to a mixing process by shaking in a conventional device so that it is Obtain a solution that is as homogeneous as possible from the start. For this, the cellulose is diluted with water in an average proportion of 2.5%, which, left at rest between 12 and 24 hours, proceeds to a shake of between 7,000 to 12,000 rpm.

2 ° .- Once the solution (1) has been obtained, the true procedure object of the invention begins, consisting in that in a compression chamber (2) the solution (1) is subjected to an average pressure (P) of / - 425 bars . Said chamber will be in contact and limited by one of its walls by the nozzle (3), and in turn, the chamber will have the compression device (12) which in turn directs the solution (1) to said nozzle (3) and its step (4).

3 ° .- It is in the central and main stage of the present invention, where the solution (1), subjected to a pressure (P) of / - 425 bars, is directed to the nozzle (3) through its frustoconical inlet (5 ), at which time there is a strong acceleration to the solution (1) since, in a space of / - 5 millimeters that the frustoconical inlet (5) has depth, the solution passes a speed of / -0, 02m / s at / -120m / s velocity (V) (limit flow velocity conditioned by friction with the walls) with which it will pass through the passage (4) of the nozzle (3), that in this case we have given it a diameter of / -0.6mm and a length of / -8mm to start the exit towards the conical exit part (6), which will have a depth of / -5mm where a slight expansion and decompression. All this causing, in said passage through the nozzle, a strong friction (R) of the compressed solution (1) and at high speed (V) on the wall (9) of the frusto-conical inlet (5), as well as the wall perimeter (10) of the passage (4), and finally of the wall (11) of the frusto-conical outlet (6), friction (R) which in turn will cause the strong turbulence (T) in the solution (1), occurring in This central stage and in combination with the nozzle (3) and its arrangement most of the pulp fiber removal, and consequently, a significant obtaining of nanocellulose, since with the acceleration of / -0.02m / s / -120m / s in a space of / - 5 millimeters, molecularly the solution (1) would undergo an acceleration in such an important way that, in step (4) with the friction (R) in the perimeter wall (10), there is the shredding in principle longitudinal in the direction of entry to exit of the solution (1) and in particular in the bleached cellulose that is diluted in the solution ( 1).

Note that a nozzle (3) can have one or more passages (4) with their corresponding frustoconical inlets and outlets (5) and (6) respectively.

4 ° .- To reach a final and complementary stage of the process for obtaining nanocellulose, in solution (1), when said solution (1) leaves the nozzle (3) through the frustoconical outlet (6) at a reception chamber (7) in which in this case of a preferred embodiment, we are going to determine a zero pressure, but in which, the solution that comes out of the nozzle (3) at an average pressure (P) of / - 425 bars, together with an average speed of / -120m / s, faces a total decompression, causing a strong expansion (E) of the solution (1), which will hit all the walls of the receiving chamber (7) and very particularly and to a greater extent it will collide with the dead center (8) that is arranged in the reception chamber (7) and this due to the high speed and the inertia itself with which the solution (1) comes out of the nozzle ( 3) through the frusto-conical outlet (6).

5 ° .- Stages two, three and four can be repeated as many times as deemed appropriate and necessary for the most optimal obtaining of nanocellulose, resulting in the third central stage in which the greatest defibration is obtained and the obtaining of nanocellulose to move on to this last stage. The latter so that, through conventional procedures (centrifugation), the solution (1) is separated: on the one hand the water and on the other the nanocellulose. In this way, the procedure for obtaining nanocellulose will be concluded, having nanocellulose with the characteristics that are considered appropriate and necessary.

The device that would be used to put this procedure into practice, and this is deduced from the description made, is the combination of:

- A compression chamber (2) which on the one hand would have the compressor (12) which in turn would push the solution (1) and on the other hand would face a nozzle (3), which would have a passage ( 4) towards which the solution (1) would be directed once compressed.

- A nozzle (3) which, in combination with the compression chamber (2), would receive the solution (1) with pressure (P) through its frusto-conical inlet (5) that, as a funnel, would direct the solution ( 1) in an accelerated way towards step (4) through which the solution (1) would pass at a speed (V) of / -120 m / s, with a strong friction (R) on its perimeter wall (10), which in turn, it would cause turbulence (T) so that the solution would pass through the frusto-conical outlet (6) to the reception chamber (7) with which the nozzle (3) is also in combination on the other hand.

- A reception chamber (7) that, in combination with the nozzle (3) and the solution (1), receives it with a velocity (V) of / -120m / s with a compression of / -425 bar, to pass to a zero pressure, which will cause decompression and corresponding expansion (E) of the solution (1) that by its own inertia will collide with the dead center (8) that the reception chamber (7) has.

This device can be complemented with a cooling system (14) of the entire set, that is, compression chamber (2), nozzle (3) and reception chamber (7), because taking into account the pressure (P) and friction (R) in combination with turbulence (T), speed (V), together with expansion (E) and decompression, heating occurs that can sometimes be too high, so that all the air can be cooled. device to ensure its proper functioning.

This will be the device with the basic elements that will put the procedure into practice in the central and main stages of the present invention, which are stages two, three and four, as has been described.

It is a whole procedure and device object of the invention to obtain nanocellulose, by means of defibration through the combination of pressure, acceleration, speed, friction, turbulence, expansion, decompression and shock, in a mechanical and non-chemical way. .

Claims (10)

1. - Defibration procedure to obtain nanocellulose of which, being mechanical, it is characterized in that starting from a bleached cellulose diluted in water, it is subjected in a combined and continuous way to steps of pressure (P), acceleration, speed (V), friction (R), turbulence (T), expansion (E), decompression and shock, to obtain a defibration and nanocellulose. 2. - Procedure according to claim 1, characterized in that they perform the following steps in combination: - A first stage in which the solution (1) consisting of a mixture in a proportion of between 1% and 6% of bleached cellulose diluted in water is subjected to a pressure (P) of between 250 and 600 bars in a pressure chamber (2) compressing the solution (1). - A second stage in which the compressed solution (1) is passed through the nozzle (3) in which: a) In its frusto-conical entrance (5) of a length of / -5mm with a perimeter of the outer ring concurrent with the compression chamber (2), always greater than the inner one that will concur with the perimeter of the passage (4), the solution (1) it goes from a speed (V) of / -0.02m / s to 120 m / s, causing a very strong acceleration of the solution (1) and the first shredding. b) In its step (4) and carrying the solution (1) the pressure (P) of between 250 and 600 bars, at a speed (V) of between 100m / s and 200m / s, it produces a strong friction (R) in the perimeter wall (10) of the passage (4), which in turn causes a strong turbulence (T) in the solution (1), causing the second shredding. c) To go to the frustoconical outlet (6) of the nozzle (3) arranged in an inverse way to that of the inlet (5), and causing the beginning of the expansion (E) decompression of the solution (1). - A third stage in which the solution (1) with an important part of the nanocellulose already obtained, precipitates in a reception chamber (7) which is at a pressure of zero to between minus 250 and minus 600 bars, which causes a strong expansion (E) with the decompression in the solution (1), which together with the speed (V) with which the solution leaves the nozzle (3) produces the collision of the solution (1) against all the walls of the reception chamber (7) and very particularly against the dead center (8) that is arranged in front of the frustoconical outlet of the nozzle at a distance of between 15mm and 150mm, which again produces a third solution shredding (1) Thus obtaining the defibration and nanocellulose. 3. - Procedure according to claim 1 and 2, characterized in that said steps described can be added in a complementary, optional way, in combination, a previous step in which: - It is subjected to a previous mixing process by shaking to obtain a very homogeneous solution (1), diluting the bleached cellulose in water in a proportion of between 1% and 6%. - This solution is left to rest between 12 and 24 hours. - To later subject it to a shake of between 7,000 to 12,000 rpm. 4. - Process according to claims 1 and 2, characterized in that the steps described in claim 2 can be repeated as many times as deemed appropriate to obtain the most optimal nanocellulose on a scale of between 50 and 100 nanometers. 5. - Process according to claims 1, 2 and 3, characterized in that the solution (1) once it has passed the stages of claims 1 and 2 proceeds to the separation in a conventional way (centrifugation or decantation) of the water and of the nanocellulose obtained in the proportions in which it had been diluted between 1% and 6%. 6. - Defibration device to obtain nanocellulose which, being mechanical, is characterized in that it has in combination: a) A compression chamber (2) having the compressor (12), to compress the solution (1) between 250 and 600 bars, directing the solution (1) towards the nozzle (3). b) A nozzle (3) through which the solution (1) passes through its frusto-conical inlet (5) whose largest perimeter is always close to the compression chamber (2) and its smallest perimeter is always concurrent with the perimeter of the passage (4), its length is / - 5mm; its step (4) which has a cylindrical shape whose diameter is between 0.2mm and 2mm and its length can range between 3mm and 100mm; and its frusto-conical outlet (6) which is the same as the frusto-conical inlet (5) but arranged in the opposite way, with its smaller perimeter always joined and of the same size as that of the passage (4) c) A reception chamber (7) in which it is attached to the other side of the nozzle (3) and which receives the frusto-conical outlet (6), having a dead point (8) that is at a distance between 15mm and 150mm from the frustoconical outlet (6) of the nozzle (3), in whose chamber the solution (1) is decompressed and expands, hitting all its walls and preferably against the dead center (8). 7. - Device according to claim 6, characterized by having a dead center (8) which can be fixed or mobile and can conveniently move to provide more or less shock in combination with more or less decompression in the reception chamber ( 7). 8. - Device according to claim 6, characterized by having a decompression device (13) which independently of the dead center (8) produces a decompression less than zero, that is, a negative compression, so that the expansion of the solution (1) is greater in the receiving chamber (7). 9. - Device according to claim 5, characterized by having a cooling (14) of the compression chamber (2), the nozzle (3) and the receiving chamber (7). 10. Device according to claim 5, characterized in that the nozzle (3) has one or more passages (4) with their corresponding frusto-conical inlets and outlets (5) and (6) respectively.