WO2016159794A2

WO2016159794A2 - Multilayer, non-woven filter for emulsion separation

Info

Publication number: WO2016159794A2
Application number: PCT/PL2015/000057
Authority: WO
Inventors: Włodzimierz PIŁACIŃSKI
Original assignee: Secura B.C. Sp. Z O.O.
Priority date: 2015-03-27
Filing date: 2015-03-31
Publication date: 2016-10-06
Also published as: PL411789A1; WO2016159794A3

Abstract

The present invention relates to a multilayer, non-woven filter for the separation of an emulsion and a method for its manufacture. A new filter structure providing retention of emulsion particles with a particle size of 0.5 microns, 99.9% efficiency and flow resistance not greater than in typical, conventional filter cartridges used for the filtration of suspensions has been developed. Further, multilayer cartridges for the filtration of suspensions are provided, wherein said cartridges are suitable for installation in standard frames of conventional filters.

Description

Multilayer, non-woven filter for emulsion separation.

Description

FIELD OF INVENTION

The present invention relates to a multilayer, non-woven filter for the separation of emulsion particles and a method for the preparation of the said multilayer, non- woven filter.

BACKGROUND OF INVENTION

Since the early nineties of the last century, polypropylene filter cartridges have been produced. According to the prior art of the melt-blown process, the molten polymer is blown in a special nozzle using a stream of hot air to form thin fibers, which form the filter layer after cooling down. These filters provide a means to remove impurity particles from the fluid mechanical suspensions. Polypropylene filter cartridges have become the canon of industrial filtration techniques. Ranges of cartridges are manufactured in different dimensions and with different particle size filters.

KR20140073731 relates to a cavity containing a multi-layer, PTFE membrane for membrane distillation and a manufacturing method thereof. The multi-layered PTFE hollow membrane for membrane distillation, according to one embodiment of the present invention, shows a high removal efficiency of particulate contaminants through the control of fine pores while improving the backwash efficiency by utilizing pores in an outer active layer as a filter layer by minutely adjusting the pores. The multi-layer, PTFE, hollow membrane for membrane distillation includes: a cavity; a PTFE support layer which is formed along the outer periphery of the cavity; and a fluoride resin layer with a melting point lower than the melting point of the PTFE support layer.

KR101354423 discloses a multilayer, PTFE, capillary membrane with hydrophilic properties and a manufacturing method thereof. In particular, to a multilayer, PTFE, capillary membrane that removes contaminant particles with high efficiency by a fine control of pore size in the filter layer, which improves the backwash efficiency using an external active layer with finely controlled pores as a filter layer, improved porosity and water penetrability, and has excellent elimination rates and filtering efficiencies.

DE102012010307 shows the multilayer filter material that has a main portion provided with a pre-filter layer, a main filter layer and an absolute hydrophilic or hydrophobic filter layer. The pre-filter layer is made of wet or dry non-woven fabric material. The main filter layer is made of wet non-woven fabric material comprising cellulose fibers, synthetic fibers, inorganic fibers or a mixture of fibers. The absolute filter layer is made of melt-blown, non-woven fabric. The pre-filter layer is manufactured from a filter paper.

US2013199141 discloses a multilayer filter medium, which is used as a constituent member of a filter and has a multilayer structure. The filter material comprises a wet type, nonwoven, fabric layer A containing 0.5 to 20% by weight, based on layer weight, of short-cut nanofibers that are composed of a fiber-forming thermoplastic polymer, have a single fiber diameter (D) of 100 to 1 ,000 nm and are cut so that the ratio (L/D) of the length (L) to the single fiber diameter (D) is within the range of 100 to 2,500 and core-sheath conjugate type binder fibers having a single fiber diameter of 5 pm or more, and a nonwoven fabric layer B having a lower density than that of the wet type nonwoven fabric layer A. A filter uses the multilayer, filter material and has the nonwoven fabric layer B arranged on the fluid inlet side. CN 102470302 discloses an air filter material, that uses a multilayer electret nonwoven fabric obtained by arranging one or more layers of a nonwoven fabric (a nonwoven fabric B), formed from fibers having an average fiber diameter of 10- 100 pm, on at least one surface of a nonwoven fabric (a nonwoven fabric A), which is obtained by mixing two kinds of fibers that have an average fiber diameter of 0.1-15 pm and different melting points (hereinafter the fibers having the lower melting point are referred to as the fibers D and the fibers having the higher melting point are referred to as the fibers E), and subjecting the resulting multilayer nonwoven fabric to electret processing. In this respect, the average fiber diameter of the fibers constituting the nonwoven fabric B is larger than the average fiber diameter of the fibers constituting the nonwoven fabric A. The multilayer electret filter material has a low pressure loss and a high collection efficiency. The filter material is suitable for applications as masks for medical use, masks for industrial use, masks for general use, and the like.

European Patent Application EP2433695A1 relates to a multilayer filter structure comprising at least one pre-filter layer, at least one fine dust filter layer and at least one supporting layer, which is respectively, arranged one behind another in the direction from the inflow side to the outflow side. The pre-filter layer is made of a melt-blown, nonwoven fabric, which is present in the form of non-interconnected filaments, and this filament thickness is less than 15 pm. Independent claims are also included for: (1) a dust filter bag comprising the multilayer filter material in its wall; (2) a pocket filter bag comprising the multilayer filter material in its wall; and (3) a pleated filter comprising the multilayer filter material in its wall.

The multi-layered filter structure is used to remove dust from fluids. It shows a high capacity for retaining dust, a high mechanical stability and is composed of a large number of fibers of small diameter, therefore with better separation performance, and contains fibers with a single fiber diameter, thereby avoiding the clumping together of individual fibers. The frequency distribution of filament diameters within the melt-blown pre-filter layer substantially corresponds to a steady uniform distribution. The average fiber diameter of the melt-blown pre-filter is lower than 10 μιτι, preferably 5 μιτι. The supporting layer is formed from a staple fiber nonwoven fabric or an extrusion nonwoven fabric. The basis weight of the melt-blown pre-filter layer is in the range of 20-500 g/m². The basis weight of the fine dust filter layer is in the range of 5-100 g/m². The basis weight of the support layer is in the range of 10-200 g/m². The thickness of the melt-blown pre-filter layer is between 0.5-20 mm. The melt-blown pre-filter, the fine dust filter layer and the support layer are formed from thermoplastic polymers.

The melt-blown pre-filter and/or fine dust filter layer forming filaments are provided with an electrostatic charge and/or hydrophilicity. In other embodiment, additionally or optionally, the melt-blown pre-filter and/or fine dust filter layer forming filaments are provided with an antimicrobial additive or further additives. In another embodiment, the inflow side in front of the melt-blown pre-filter is arranged a further pre-filter layer, which is formed from an extruded, nonwoven fabric.

CA2748248 discloses a filtration material for filters, which comprises a sheet-like multilayer body wherein a ultra-fine fiber assembly layer, which is composed of an assembly of ultra-fine fibers produced by an electrospinning method and having an average fiber diameter of not less than 10 nm but not more than 1000 nm, and a base, which is composed of a nonwoven fabric or woven fabric formed from fibers having an average fiber diameter of not less than 1 μιη, are laminated. The filtration material for filters satisfies all of a plurality of specific conditions. Consequently, the filtration material for filters has an ability of collecting or separating fine particles of the micron order with high precision, while having a low pressure loss and long filtration life. Also disclosed is a filter cartridge using the filtration material for filters.

JP2011088349 provides a multilayer, fiber structure which is low in pressure loss, excellent in delamination or suppressed in ultrafine fiber. The essence of the invention is a multilayered fiber structure comprising at least three layers of a lower layer, an intermediate layer and an upper layer. The intermediate layer is the fiber structure comprising the ultrafine fiber having a diameter of 10-500 nm, and the upper and lower layers are nonwoven fabrics comprising fibers having diameters of 1-100 pm. The upper layer and the lower layer are partially thermocompression-bonded by embossing in a cross section of a recessed part formed by the thermocompression-bonding.

None of the mentioned documents meet the requirements of the user as a filter cartridge. From contacts with customers of filter cartridges results that, in some cases, impurities present in the water form emulsion particles such as particles of another immiscible liquid, rather than particles of solid. Removal of the liquid particles by using filter cartridges, although successful, results in liquid particles depositing within the filter structure and gradually moving along the surface of the fibers, in the liquid to be filtered, and, after saturation of the filter layer , they can leave the filter with liquid. The overall efficiency of liquid filtration then gradually deteriorates.

Work has begun on the construction of filter cartridges suitable for the effective removal of liquid particles from emulsions. In some cases, the dispersed phase is formed from organic liquids, such as different solvents or oils. Therefore, we developed a filtration cartridge that comprises filter layers in its structure that have different affinities for water. Surprisingly, it was found that a filter cartridge consisting of two layers of hydrophilic fibers (wettable by water), separated by a layer of hydrophobic fibers (repellent), allows the efficient removal of particles in an emulsion.

SUMMARY OF THE INVENTION

The subject of the invention is a layered fibrous filter for the separation of emulsions, in which on a core of gossamer hydrophilic fibers, preferably polyamide, there are hydrophobic polymer fibers, preferably polymer is polypropylene , in the form of a uniform fiber layer having a thickness of 2-6 mm, on said layer the next layer is present with 5-6 mm thickness composed of hydrophilic fibers, preferably polypropylene, with a diameter in the range from 1 μηι to 10 μιτι, preferably there is a further layer of hydrophilic fine fibers, preferably polypropylene, of a thickness of 5-20 mm.

In a preferred embodiment of layered fibrous filter, on a gossamer with a core of polypropylene fibers, polyamide fibers are placed that form a homogeneous layer with a thickness of 4 mm, on said layer, a further layer is present having a thickness of 3 mm of polypropylene fibers with diameters ranging from 10 m to 60 μιη, upon which a further layer of fine polypropylene fibers is placed to a thickness of 10 mm. A layered fibrous filter is provided, which contains a polypropylene fiber layer has a thickness of 13 mm.

The present invention relates to a method for the production of a multi-layer, non- woven filter for the separation of emulsions where a core of polypropylene gossamer uses the "melt-blown fiber" technique to apply a uniform layer of nylon (polyamide) fibers, then a layer of polypropylene fibers with a diameter in the range of 10 pm to 60 μητι, and upon this layer to apply a further layer of fine polypropylene fibers.

In a preferred method according to the invention, to a gossamer core of polypropylene, the "melt-blown fiber" technique is used to apply nylon (polyamide) fibers to form a uniform layer with a thickness of 4 mm, then a layer of 3 mm thick made of polypropylene fibers with a diameter ranging from 10 microns about 60 microns, and to this layer a further layer of fine polypropylene fibers with a thickness of 10 mm is applied. The gossamer is preferably a core made of polypropylene with the "melt-blown" technique applied to polypropylene fibers with a diameter ranging from 10 μιη to 60 μηη to form a uniform layer of fibers with a thickness of 4 mm, and then a layer of polypropylene fibers with a thickness of 13 mm. In a preferred embodiment, the method provides a combination of successive layers of polymer gossamer applied to the core to provide greater strength to the filter relying on the rapid imposition of another layer of fibers using the melt-blown technique on the surface of the layer that has not yet cooled, which generates filaments to stick together in their mutual contact.

Preferably, the layers forming the filter on the gossamer structure of the core are wound onto it from flat, respectively thinner, non-woven fabric formed by the melt- blown technique using suitable polymers. It is more preferred that the filter structure formed from a core gossamer wound on flat layers of nonwoven fabrics suitable type is fixed by the application of a suitable adhesive, e.g. polymeric resin that is incorporated in an appropriate manner to the structure of the nonwoven fabric to form a connection between adjoining fibers.

In a preferred embodiment, the nonwoven filter layer separates the emulsion and a method for its preparation, the porosity of the first and second layers from the side of the filtered flow of emulsion have uniform porosity within each layer, and the third layer has a porosity increasing in the direction of flow of the liquid to be filtered.

The variable porosity of the final filter layer is obtained by applying several blow heads to the manufacture by melt-blown technology and working in other regimes of parameter sets that ensures the formation of fibers with different properties and structure of the nonwoven layer with varying porosity. In a preferred embodiment, the blown (spray) head in the melt-blown technology forms a final layer of varying porosity of the filter is controlled automatically and during the formation of this layer, it continuously changes a parameter such as airflow rate or other parameters, such as, the volume of air flow and air temperature, which results in the formation of fibers of varying diameter and the formation of a non-woven layer of varying porosity. The formed filter is preferably packed within a metal mesh, preferably of stainless steel, which provides high mechanical strength for the composite structure of the filter cartridge.

In a preferred embodiment, looking from the flow of liquid to be filtered, another layer of highly absorbent filter is added to retain the mechanical impurities in particulate form so that they do not further block the dedicated structure for removing particles in the emulsion.

DETAILED DESCRIPTION OF THE INVENTION

The provided filter cartridge, according to the invention, has in its structure filter layers with different affinities for water. Surprisingly, the filter cartridge consists of two layers of hydrophilic fibers (wettable by water), separated by a layer of hydrophobic fibers (repellent), enabling the effective removal of particles from the emulsion. The operation of such a filter cartridge is that the emulsion particles bypass the first layer fibers and do not adhere to them and deposit on the inner layer of hydrophobic fibers. During the filtering, the amount of oil phase in the inner layer increases, and it is gradually forced, under the pressure of the filtered water, toward the outer hydrophilic layer. Breaking from the inner layer filter, large droplets of oil are not stopped by a further hydrophilic layer and flow out of the filter. For this reason, that they are now large, they easily rise to the surface of the liquid where they are readily removed. Through the properly selected design of this contribution, it is also possible to provide the oil phase flowing out the top of the cartridge along the hydrophobic layer and accumulation in the upper part of the filter housing.

During the industrial research cycle, various materials suitable for the production of layers of hydrophilic and hydrophobic filter cartridge were studied, also in relation to the overlapping of these different layers. Also, there were examined the necessary parameters such as filter layers, and the porosity of molded fiber diameters to provide the desired filtration efficiency. The invention provides a new filter structure for retention of emulsion particles having a size of 0.5 microns with 99.9% effectiveness and having a flow resistance not greater than in typical, conventional filter cartridges used in the filtration of suspended solids. The invention further provides multilayer cartridges for the filtration of suspensions, wherein said cartridges are suitable for installation in standard enclosures used for conventional filters.

The invention will be further illustrated in the examples whose purpose is merely a detailed presentation of preferred embodiments of the invention.

Example 1

The gossamer core was made from polypropylene fine fibers, with diameters in the range of 0.2 μηι to 5 μηι, applied using the "melt-blown" technique to form a highly effective filter layer with a thickness of 17 mm. The filter was cut to obtain a length of 254 mm (10") to provide a single filter cartridge. The entire filter layer was uniform. This cartridge was installed in a conventional industrial filter housing and aqueous slurry of paraffin oil, having a concentration of 0.04 wt%, was passed through said filter at a rate of 600 I/ hr. The initial resistance to flow and resistance in the conditions of the filter set were examined. Also, the effectiveness of the filtration of the oil emulsion was analyzed using water samples taken before the filter and after the filter. After two hours of the test, the filter was removed from the filter housing, dried for 12 days at room temperature and weighed to determine the weight gain. The constructional features of the input are summarized in Table 1. The results of the measurements are summarized in Table 2.

Example 2

On the gossamer core made from polypropylene, nylon (polyamide) fibers were applied with the "melt-blown" technique forming a homogeneous layer of fine fibers, wherein said layer has a diameter of 17 mm. The filter was tested as in Example 1.

Example 3 On the gossamer core made from polypropylene, nylon (polyamide) fibers with a diameter in the range of 10 pm to 60 pm were applied with the "melt-blown" technique forming a uniform fiber layer with a thickness of 4 mm. Then, a layer of fine fibers of polypropylene with a thickness of 13 mm was applied. The filter was tested as in Example 1.

Example 4

On the gossamer core made from polypropylene, nylon (polyamide) fibers were applied with the "melt-blown" technique forming a uniform layer with a thickness of 4 mm, said layer was composed of fine fibers. Then, a layer with a thickness of 3 mm made of polypropylene fibers, having a diameter ranging from 10 pm to 60 pm, was applied. On this layer, a further layer of fine polypropylene fibers was applied, wherein the thickness of the layer was 10 mm. The filter was tested as in Example 1 but using a flow rate of 600 l/hr and 200 l/hr.

Example 5

On the gossamer core made from polypropylene, nylon (polyamide) fibers were applied with the "melt-blown" technique forming a uniform layer with a thickness of 4 mm. Then, a layer with a thickness of 3 mm, made of polypropylene fibers with a diameter ranging from 10 pm to 60 pm, was formed. On this layer, a further layer of fine polypropylene fibers was formed, wherein said layer had a thickness of 10 mm The filter was tested as in Example 1 but using a flow rate of 200 l/hr.

Example 6

On the gossamer core made from polypropylene, polypropylene fibers were applied with the "melt-blown" technique forming fibers with a diameter ranging from 10 pm to 60 pm as a uniform layer with a thickness of 4 mm. Then, a layer of polypropylene fibers with a thickness of 13 mm was formed. The filter was tested as in Example 1.

Example 7 On the gossamer core made from polypropylene, nylon (polyamide) fibers with a diameter in the range of 10 pm to 60 pm were applied with the "melt-blown" technique forming a uniform layer of fibers, said layer having a thickness of 4 mm. Then, a layer with a thickness of 13 mm made of fine fibers of the same material was formed. The filter was tested as in Example 1.

Table 1. Summar of the structural parameters of filter cartridges

^*) Numbering of the layers from the inner core of the filter cartridge *^*) PP polypropylene *^**) N - nylon (polyamide) Table 2. Summary of the results of the comparative tests of filter cartridges of different desi ns.

Claims

1. A multilayer, non-woven filter for the separation of emulsion characterized in that, on the gossamer core made of polypropylene fibers, there are polyamide fibers to form a homogeneous layer with a thickness of 2-6 mm, thereon the next layer is present with a thickness of 5-6 mm made of polypropylene fibers having a diameter in the range of from 10 pm to 60 pm.

2. The multilayer, non-woven filter according to claim 1 , characterized in that the next layer of fine polypropylene fibers with a thickness of 5-20 mm is present on the layer having a thickness of 5-6 mm composed of polypropylene fibers having a diameter in the range of from 10 pm to 60 pm.

3. The multilayer, non-woven filter according to claim 2, characterized in that the next layer of polypropylene fibers has a thickness of 10-13 mm.

4. The multilayer, non-woven filter according to claims 1 or 2, characterized in that on the gossamer core of polypropylene fibers, there are polyamide fibers present in the form of a homogeneous layer with a thickness of 4 mm, on said layer a further layer is present with a thickness of 3 mm, wherein said layer is made of polypropylene fibers with a diameter ranging from 10 pm to 60 pm, on which a further layer is present, wherein said third layer is made of fine polypropylene fibers and has a thickness of 10 mm.

5. The multilayer, non-woven filter according to any of claims 1-4, characterized in that the porosity of the first and second layers, looking from the side of the filtered flow of emulsion, are of the uniform porosity within each layer and the porosity of third layer increases in the direction of flow of liquid to be filtered.

6. A method for making a multilayer, non-woven filter for the separation of emulsions, characterized in that said method comprises steps of using the "melt- blown" technique to apply the nylon (polyamide) fibers to an gossamer core of polypropylene to form a uniform layer of fibers, then applying a layer of polypropylene fibers having a diameter in the range of 10 pm to 60 pm, followed by application of the next layer of fine polypropylene fibers.

7. The method according to claim 6, characterized in that said method comprises applying with the "melt-blown" technique the nylon (polyamide) fibers on a gossamer core made of polypropylene, to form a uniform layer having a thickness of 4 mm, then introducing a layer of 3 mm thickness of polypropylene fibers having a diameter in the range of 10 pm to 60 pm, and applying thereon the next layer of fine polypropylene fibers, wherein said layer has a thickness of 10 mm.

8. The method according to claim 7, characterized in that using the "melt-blown" technique applying the polyamide fibers with a diameter ranging from 10 pm to 60 pm on an gossamer core made of polypropylene, to form a uniform layer of fibers with a thickness of 4 mm, and then introducing a layer of polypropylene fibers, wherein said layer has a thickness of 13 mm.

9. The method according to any of claims 6-8, characterized in that the next fiber layers are applied using melt-blown technique before the surface of the previously formed layer cools down, to provide adhesion between the filaments on contact sites of the fibers.

10. The method according to any of claims 6-8, characterized in that the next layers forming the filter on the gossamer core structure are wound from a flat, thinner with respect to the gossamer core, nonwoven fabric prepared with melt- blown technique.

11. The method according to claim 10, characterized in that the filtering structure of the flat layers of nonwoven fibers wound on the gossamer core are fixed with adhesive polymeric resin that is incorporated into the nonwoven structure to create a connection between adjoining fibers.

12. The method according to any of claims 6-11 , characterized in that for forming the final filtering layer, several blow heads in melt-blown technology are used in the operating regimes with different parameter sets to form fibers with different properties and nonwoven structure of varying porosity.

13. The method according to claim 12, characterized in that the method comprises the steps of varying continuously air flow rate and/or volume of air flow and/or air temperature of the blow head in the melt-blown technology to form a final layer of variable porosity.

14. The method according to any of claims 6-13, characterized in that the porosity of the first and second layers looking from the inflow of the filtered emulsion has uniform porosity within each layer and the third layer has an increased porosity in the direction of the flow of filtered liquid. _¾

15. The method according to any of claims 6-14, characterized in that the formed filter is packed within a metal mesh, preferably of stainless steel.

16. The method according to any of claims 6-15, characterized in that from the side of inflow of liquid to be filtered, an additional filter layer is added with a high absorbency.