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Title:
ELECTRODE FOR SURFACE PROCESSING OF POLYMER MATERIALS
Document Type and Number:
WIPO Patent Application WO/2019/158135
Kind Code:
A1
Abstract:
The present application relates to an electrode for surface electrostatic processing of polymer material. The electrode consists of a spinning strip and a coating element that supplies and spreads a spun solution to produce fibrous or particulate nanosystems by means of an electromagnetic field generated by a voltage source with a potential difference range of 0-250kV. The application relates also to the spinning strip and a device functioning on a base of an electrode.

Inventors:
BUZGO, Matej (Moldavska cesta 233/74, Turna n/B, 044 02, SK)
DOUPNIK, Miroslav (Kratka 485, Strmilov, 378 53, CZ)
DOUPNIK, Martin (Okruzni 234, Tisice, 277 15, CZ)
Application Number:
CZ2019/000010
Publication Date:
August 22, 2019
Filing Date:
February 13, 2019
Export Citation:
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Assignee:
INOCURE S.R.O. (Klimentska 1652/36, Nove Mestro, Praha 1, 110 00, CZ)
International Classes:
D01D5/06; D04H1/728
Attorney, Agent or Firm:
ZUSKA, Jaroslav (Plzenska 261, Praha 5, 155 00, CZ)
Download PDF:
Claims:
Patent claims

1. Electrode for surface electrostatic processing of polymer materials consisting of spinning strip and coating element that supplies and spreads the spun solution to produce fibrous or particle nanosystems by means of electromagnetic field generated by voltage source with potential difference range of 0 - 250 kV.

2. Spinning strip meeting Condition 1 (1-50 separate elements) consists of metallic (mainly compounds of Fe, Mg, Cu, Cr, Al, Ni, Sn) and/or non-metallic materials (glass, PEEK, POM, PE, PP, ceramics) with different cross-section that can be rectangular, polygonal (n > 2, side length 0.1 mm to 10000mm), concave or convex element (diameter 0.1 mm to 10000mm) or any of their combinations.

3. Electrode meeting Condition 2 consists of a spinning strip with one or several elements of circular, ellipsoidal, unclosed circular, unclosed ellipsoidal (with diameter ranging between 20 cm to 1,000 cm) and of a coating element supplying the spinning solution.

4. Electrode meeting Condition 2 with a spinning strip consisting of a linear element (length 10 cm to 1,000 cm) and coating element supplying the spinning solution.

5. A coating element for the electrode meeting Condition 1 supplying the atomisation material by delivering it to the top side of the spinning strip pursuant to Conditions 2, 3 and 4. The coating takes place upon the movement of the strip and the coating element.

6. Device meeting Condition 5 functioning on the principle of static spinning strip and moving coating element for the delivery of the spinning solution (0 rpm to 20,000 rpm).

7. Device meeting Condition 5 functioning on the principle of moving spinning strip and static coating element for the delivery of the spinning solution (0 rpm to 20,000 rpm).

8. Device functioning on the basis of an electrode meeting Conditions 1 to 7 for producing fibres or particles with application in medicine, surface treatment, chemical analysis, cosmetics, and in the food industry.

AMENDED CLAIMS

received by the International Bureau on 25 July 2019 (25.07.2019)

Claims

1. Electrode for surface electrostatic processing of spin fluids consisting of electrode base holding the spinning strip, horizontally or vertically curved spinning strip and coating element powered by motor that slides on the top surface of the curved spinning strip and spreads along the spun solution delivered by pump to produce fibrous or particle nanosystems by means of electromagnetic field with potential difference range of 0 - 250 kV between the electrode and counter electrode in form of plate or strip or ring generated by one or multiple voltage sources, characterized that facilitates homogenous electrostatic field formation on horizontally or vertically curved spinning strip for improved homogeneity of formed fibers for particles, adapting of electrode shape to facilitate formation of desired spinning and spraying patterns, increased throughput by induction of multiple maxima of electrostatic field in sharp edges of spinning strip, improved mechanical stability due to embedment of spinning strip to electrode base eliminating mechanical breaking of electrode, homogenous delivery of spin fluid to the defined surface of curved spinning strip by coating element for reproducible formation of electrostatic jets on the surface of spinning strip, concentration of spin fluid to the centre of spinning strip and self-cleaning of spin solution by coating element improving reproducibility of spin fluid processing.

2. Electrode base element meeting Condition 1 is securing the spinning strip on exact position (contact of spinning strip and electrode base elements ranging from 10-100% of spinning strip surface) and eliminates vibrations during electrostatic processing of spin fluid.

3. Spinning strip element meeting Condition 1 serving as surface for electrostatic processing of spin fluid (1-50 separate elements) consists of metallic (stainless steel listed in EN10088-1 , steel listed in EN10027-2, bronze alloys listed in EN1982, aluminium alloys listed in EN573-1 or their combination) and/or non-metallic materials (glass, PEEK, POM, PE, PP, ceramics or their combination) with different cross-section combining polygonal (n > 2, side length 0.1 mm to lOOOOmm) strips (dimensions 0,lmm-l000mm) with polygonal (n > 2, side length 0.1 mm to lOOOOmm), concave or convex elements (diameter O. lmm to lOOOOmm) on the spinning surface to enhance electrospinning and electrospraying process efficacy.

4. Spinning strip meeting Condition 3 consists of one or several elements with curvature along the horizontal plane (radius of curvature 5-2000 cm) forming element with circular or elliptical shape and creating homogenic electric field distribution in range 1 - 0.8 measured as ratio of electric field intensities of any two points of along the centre of spinning strip.

5. Spinning strip meeting Condition 3 with linear shape (length 10 - 1000 cm) and curved surface in vertical plane (radius of curvature 100-10000 cm) homogenizing the electric field distribution on spinning strip to 1 - 0.8 when measured as ratio of electric field intensity in the centre of spinning strip and 5 cm from edges of spinning strip.

6. A coating element meeting Condition 1 consisting of part connecting the coating element to motor, sliding part with body made of non-metallic material (glass, PEEK, POM, PE, PP, methacrylates, ceramics or their combination) and pressing system composed of springs and hinges to slide along the surface of curved spinning strip; and spin fluid distribution part consisting of or multiple channels in the body of coating element delivering the spin fluid to the centre of spinning strip in defined line with diameter 0.2 - 4 mm along the length of spinning strip.

7. Electrode meeting Condition 1 functioning on the principle of static linear vertically curved spinning strip meeting Condition 5 and moving coating element meeting Condition 6 for the delivery of the spin fluid (0-100 Hz) powered by motor transmitting movement to coating element sliding on the surface of spinning string described in Condition 5 and depositing the spin fluid to the top curved surface of the spinning strip.

8. Electrode meeting Condition 1 functioning on the principle of static circular or elliptical spinning strip meeting Condition 4 and moving coating element meeting Condition 6 for the delivery of the spin fluid (0 rpm to 20,000 rpm) powered by motor transmitting movement to coating element sliding on the surface of spinning strip meeting in Condition 4 and depositing the spin fluid to the top surface perpendicular to the central axis of circular or elliptical spinning strip.

Description:
Electrode for surface processing of polymer materials

Field of technology

Methods of electrostatic spinning and spraying represent a recognised technique for preparing nanosystems in the form of nano fibres or nano particles. The technical solution is based on the use of surface spinning by means of a new electrode for electrostatic spinning and spraying that increases the production capacity, utility value, and efficiency of the existing solutions. The technical solution includes a description of the potential technological application of the presented electrode.

Current state of technology

Electrostatic techniques are used to create functional nanosystems. Their practical applicability is substantially limited by the production capacity of the current methods. Currently there are no industrial techniques available for the production of nano particles using electrostatic methods and strong electromagnetic field. The presented solution changes this status quo and enables the industrial production of both nano fibres and nano particles by means of electrostatic methods. At the moment, the majority of electrostatic processes are based on needle spinning systems that produce fibre from liquid or melt delivered by a capillary (needle) and subject to strong electrical field. The drawbacks of the current solutions include especially the low production capacity eliminating commercial applicability of the products. An example is a solution described in EP 1709218, EP2045375, EP2447396, JP2008248422, US67535454, US7575707, US8088324, and US2014353882.

The solution is based on the creation on so-called surface electrodes leading to the production of nano fibres and nano particles by means of self-organization from the surface of a thin polymer layer. Surface electrodes demonstrate a variety of construction solutions in terms of their electrical field homogeneity design, the method of the liquid coating, elimination of the dead volume of polymer solutions, and removal of excess solutions. However, none of the existing solutions allows for adaptation for producing both nano fibres and nano particles in industrial applications. The simplest surface design is the application of rod electrodes that allow for spinning from a drop of polymer liquid brought to the rod element. An example is an electrode described in patent CZ304097. This solution is suitable mainly for the production of small volumes of polymer particles or fibres. The reason is the limit of the free surface allowing for the self- organization of just a limited number of polymer nozzles and therefore for their limited function. An example of this is the production of fibres from polymer solution in the form of foam. When bubbles are produced, fibre nozzles self-organize on their surfaces and so spinning process takes place as well. The design is described e.g. in EP2142687.

The issue of limited effective spinning surface of rod electrodes is mitigated by use of linear electrodes. Linear electrodes are limited in terms of their adaptation for particle generation and so it is necessary to integrate them in reactor systems if used for industrial production. In terms of air flow and spatial efficiency it is necessary to use circular or ellipsoidal systems. This makes linear electrodes suitable only for producing nano fibre layers. The simplest example of linear electrodes represents slotted electrodes consisting of two strips with polymer fluid flowing between them. The slots deliver the polymer fluid to the active spinning zone (so-called slotted electrodes).

Slotted electrode with segmented channels is described in patent CN2037754858. Slotted electrode with alternative effect of compressed air is described in patent CZ2012514, US20151522572 and EP2617879. A similar design, except the separation of pressure air slot diffusers and slot spinning electrodes into separate elements, is described in patent JP5383937 and JP2013124426. The design described in patent CZ302876 is based on the production of nano fibres from an electrode that contains one or several slots that deliver the material to the conductivised strip over which the fluid flows. Spinning occurs at the moment of overflow and fibres are produced. A similar solution with a circular overflow edge is described in patent CN103572388. A solution with overflow through a strip with triangular cross-section is also described in patent US8968626; it allows for processing of several fluids at the same time. Patent US9034240 develops the slotted electrode technology by adding further shapes, from linear, concave, to convex.

The design described in patent application EP2173930, WO2012139533, CN 103603065 and CZ20110212 presents a technique of nano fibre production by means of applying polymer solution on a string. The design describes a wire-form electrode with a stationary or mobile spinning zone onto which the polymer is applied.

The principle of our presented technical solution differs from the above stated designs and eliminates the shortcomings of designs presented in applications EP2173930, WO2012139533, CN103603065 and CZ20110212. The presented design issues from the use of a spinning strip as the most suitable application element. The main advantage of the strip for spinning is the possibility to create linear, ellipsoidal, or circular electrode shapes and to adjust its shape and dimensions to the needs of the fibre or particle deposition. For an industrial production of particles through electrostatic spraying it is necessary to adjust the shape of the electrode into a circular or ellipsoidal shape to achieve an optimal function in reactor systems. The reason for the elimination is the aberrant deposition caused by turbulent air flow and according to numeric simulations the most optimal shape of the reactor is circular or ellipsoidal. Designs in applications EP2173930, WO2012139533, CN103603065, and CZ20110212 do not allow for a similar arrangement and are therefore useless for a practical production of nano particles in industrial conditions.

The geometric shape of the string leads to the concentration of the field in the highest point of the string and to production of nano systems limited to this area only. Our presented solution based on the strip generates more maximums of the electrical field concentrations thanks to the shape of the spinning strip and leads to the production increase of electrostatic spinning and electrostatic spraying processes. Our presented solution also eliminates the risk of mechanical damage of the electrode during the process, where a string electrode may be interrupted and therefore lose function. Strip electrode, on the other hand, is mechanically rigid and set in the structure of the device to eliminate damage. The polymer solution is not applied on the electrode from all sides such as in document CZ20110212 and WO20122139533, but is applied to the top side of the spinning strip only. This eliminates dripping and allows for achieving a more homogeneous and higher quality layer than that coming out of design solutions in CZ20110212 and WO20122139533. Our presented solution also deals with the edge effects thanks to the non-linear shape of the electrode. String or chain electrodes do not allow for adjustment to an optimal shape at the ends of the spinning zones, producing non-homogeneous nano systems. The strip electrode allows for adjusting the shape of the spinning zone thanks to the compact and mechanically rigid shape of the electrode. Also, unlike the passive coating technique described in WO2012139533 and CZ20110212, where the spinning string receives only adherent material the volume of which is defined by the size of the dosage element dies, i.e. by the difference between the intersections of the transversal area of the string and transversal area of the hole in the applying device. This leads to a limited possibility of regulating the thickness of the layer and the volume of the polymer applied. Our design involves a defined volume applied to the surface of the spinning strip by dosage from active dosing element (pump). This enables for the increasing of the dosed volume also for viscous and poorly adhering fluids and a higher control over the volume of the applied fluid in time. Our solution therefore allows for processing a broader range of materials. The presented system allows for changing the amount of the applied material without the need for a hardware intervention in the apparatus. Furthermore, the presented technical solution allows for wiping off the excess polymer and its arranging in a defined shape on the surface of the spinning strip. This ensures a more efficient process of nano system production by means of electrostatic forces.

The alternative solutions described in applications DE10136255 and US7967588 do not deal with an adaptation for industrial production of nano particles. They focus on the technology of nano fibre production only.

DE10136255 describes an equipment for producing fibres by means of electrode consisting of parallel wires set on two endless bands around two guiding rollers; in the lower part the polymer is applied to the wires and the spinning effect occurs once the wires enter the electric field. The drawback of the design solution described in document DE10136255 is the open stock container causing evaporation of solvents that affect and alter the polymer solutions. This changes the properties of the solution during the spinning process and causes nonhomogeneity of the produced layer. Similar drawbacks are characteristics also solutions described in documents CZ20032421, EP1673493, CZ2006545, US20140302245,

KR1020110078016, and W02007111477, which focus on surface spinning from a cylindrical electrode rotating in the polymer solution stock container. The drawback of this solution is the low focus of the electric field and the shortcomings of the polymer stock containers. As the spinning roller electrode must get in contact with the polymer solution prior to entering the active spinning zone, solvents evaporate from volatile solutions even before entering the active spinning zone. In terms of construction there is more dead volume than in the presented solution, which reduces the utility value of the design. A similar solution, involving an electrode that contains rotating rings or discs instead or rotating cylinders, is described in document CN102828259 and CN103484953. Document CZ305037 describes a cylindrical spinning electrode made of non-conductive materials. Document JP2015132028 describes spinning from two mutually moving rollers where one roller is dipped in the spinning fluid and its rotation delivers the fluid onto the second roller that brings it into the spinning zone. Document US8545207 describes a spherical or polygonal electrode that rotates in the polymer fluid.

Document US7967588 described spinning from a strip electrode that rotates in an endless band between the spinning fluid container and the electrostatic spinning active zone. A similar solution is presented in document US8366986. The drawback is the varying quality of the fibre in the beginning and at the end of the active zone caused by the wearing and evaporation of the solvents on the electrode. Also, due to the constant motion of the band, the maximum production of fibres occurs on the entrance to the active spinning zone and the production gradually reduces towards the end of the spinning zone due to the spinning fluid not being refilled. The solution described in this application overcomes the technology thanks to a more stable spinning process and homogeneous spinning properties along the entire length of the active spinning zone of the electrode.

Document CZ2010648 focuses on spatial optimisation of the placement of long electrodes. The equipment consists of long electrodes placed underneath each other so that each of them has a collecting electrode on both sides and in the same direction. Due to this, spinning occurs between the spinning electrode and at least two of its collecting electrodes. This makes the process more efficient, where both electrodes spin at the same time. The technical solution claimed by this application allows for a combination with one collector of cylindrical, plate, punched plate, or string shape.

The principle of the technical design solution

The principle of the presented design solution is a new design of electrode for electrostatic spinning and spraying that increases the production capacity and efficiency of the existing solutions. The electrode allows for industrial production of nano fibres and nano particles with the possibility to change the shape of the electrode upon the specific requirements of the individual types of nano systems.

The electrode consists of two main parts - the spinning strip onto which the polymer is applied and from which the spinning or spraying process occurs, and an application device for the delivery of the polymer to the spinning strip.

The electrode contains one or more conductivised spinning strips onto which the polymer is delivered by means of a moving supply mechanism. The spinning strip is made of conductive (mainly compounds of Fe, Ni, Zn, Sn, Cr, Al or Cu) or non-conductive materials (mainly glass, plastics - polyoxymethylene (POM), polyethylene (PE), polyetherketone (PEEK)). The spinning strip provides a benefit compared to the existing solutions - it increases the effective surface of the active spinning zones, improves the mechanical stability of the electrode, and minimizes wear in a long-term operation. The spinning strip may have the spinning zone arranged in a linear, ellipsoidal, or circular shape. Thanks to this it allows for choosing the optimal shape by the type of the nano system produced. For producing nano fibres, linear shape of the spinning strip is ideal, which makes a spinning zone allowing for large-area deposition of the fibre into non- woven textile. For producing nano particles it is best to use an ellipsoidal or circular shape of the spinning strip and therefore also of the spinning zone.

In case of full curvature of the spinning strip a circular or ellipsoidal element is produced, with the diameter or 20 - 1,000 mm. The element may be also shaped as an unclosed curved shape in the form of one or more panels. The purpose of the radially curved electrodes is the production of nano systems in circular chambers where the radial shape of the electrode allows for optimal production of nano systems and eliminates aberrant effects such as sticking to the walls of the chamber. In this arrangement, the inventory serves mainly for industrial production of nano particles.

The spinning strip may come in an unclosed linear shape with the length of 10 - 1,000 mm without curvature for linear layers deposition. The structure of the electrode created homogenous or non-homogeneous electrical field on the spinning strip, which is achieved by the side curvature at the ends of the spinning strip leading to the adjustment of distribution for achieving maximum production in the active spinning zone. The spinning strip thus allows for increasing the homogeneity of production and production capacity.

The cross-section shape of the spinning strip may consist of a combination of shapes:

- Rectangle or square defined by its width and ranging between 0.1 mm and 1,000 mm. The height of the shape may range between 1 mm and 10,000 mm;

- Polygon with n points where n equals to 2 - 50 and the links between the points form surfaces with the diameter of 0.1-1,000 mm;

- Concave or convex radial surface with 0.1 mm - 10,000 mm in diameter;

- Combination of the partial shapes such as polygons, concave shapes, and other shapes.

The polymer is applied onto the spinning strip from the top, by means of a mechanical element connected with the polymer fluid stock container. Unlike the existing solutions it allows for an accurate application of the spun fluid on the upper part of the active spinning element only. The application of the polymer onto the surface of the spinning strip is ensured by the movement of the strip and the application element. The application element is made of polymer materials (e.g. POM, PE, PEEK), glass, ceramics, or metals (mainly compounds of Fe, Ni, Zn, Sn, Cr, Al, or Cu). The application element is connected to the source of the polymer and allows, especially in configuration with the dosage pump, for an accurate regulation of the polymer volume delivered onto the electrode. The system is characterised by allowing to apply a defined polymer coating onto the spinning strip by means of direct dosing and thus to affect the thickness of the applied polymer layer. The dosage system may work on the principle of gravity flow of the fluid or mechanical forces (e.g. injection, peristaltic, piezoelectric, centrifugal, or pressure forces). Thanks to the periodical motion along the electrode it also cleans it from excess polymer and extends spinning times compared to the method of coating sans moving parts (e.g. needle electrode technique).

The electrode is integrated into the device for electrostatic spinning or spraying. The conductivisation of the electrode is achieved by connecting to a source of direct or alternating current capable of generating 0 - 250 kV. A charged electrode, onto which the polymer solution is applied, allows for atomisation of the solution or melt in the form of particles or fibres. The movement of the mechanical parts is provided by a shielded moving apparatus that typically consists of a motor. The moving apparatus drives the rotating mechanical parts with the speed of 0 - 20,000 rpm and the linear parts with 0 - 100 Hz frequency. The moving mechanical part is the moving spinning strip and/or the application element.

The electrode allows for processing polymer (mainly lipids, polyesters, polyurethanes, polyalcohols, polyvinyl derivates, fluoridised polymers, polyamides, polyacrylates, biopolymers) of organic (mainly solutions of drugs, vitamins, cosmetic additives) or inorganic (mainly salts, oxides, sulphides, carbides, phosphates, carbonates, or silicates) solutions or melts. The electrode is designated for processing mixtures of these solutions or melts. The electrode can process colloid solutions in the form of emulsion (e.g. water/oil, oil/water, oil/water/oil types of emulsions) and dispersions (e.g. nano and micro particle dispersions). The technique allows for transforming the components from the form of solutions into solid or semi-fluid state of matter. The electrode is designated for encapsulation of live systems such as cells, bacteria, yeast, thrombocytes, or their parts (organelles, lyzates, secreted parts).

Example of inventory design

An enclosed circular or ellipsoidal spinning strip. A design in which the electrode is represented by an enclosed or ellipsoidal spinning strip. The spinning strip is fixed in the device of allow for the flow of air through the equipment. The spinning strip is connected to high voltage sources and induces high voltage. A collecting electrode with the opposite charge is typically placed opposite the electrode. The solution is applied to the electrode by means of a moving application element. The application element delivers the solution from the reservoir represented e.g. by a pressure pump. During the application of the solution the material flows from the strip electrode to the collecting electrode due to the effect of electrostatic forces. The system of the electrodes is placed in a chamber with the Faraday cage. In a similar design the equipment contains a series of parallel or radially arranged electrodes to increase the system’s productivity.

Industrial application

The produced fibres and particles may be applied in a wide range of various fields. The most important ones are medical applications, such as micro or nano carriers for controlled delivery of drugs, proteins, and nucleic acids. Other areas include the food and pharmaceutical industry.