CA1098771A - Backing for semipermeable membrane - Google Patents
Backing for semipermeable membraneInfo
- Publication number
- CA1098771A CA1098771A CA292,368A CA292368A CA1098771A CA 1098771 A CA1098771 A CA 1098771A CA 292368 A CA292368 A CA 292368A CA 1098771 A CA1098771 A CA 1098771A
- Authority
- CA
- Canada
- Prior art keywords
- woven material
- backing
- membrane
- woven
- semipermeable membrane
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000012528 membrane Substances 0.000 title claims abstract description 28
- 239000000463 material Substances 0.000 claims abstract description 37
- 238000003490 calendering Methods 0.000 claims abstract description 12
- 239000004745 nonwoven fabric Substances 0.000 claims description 16
- 239000000835 fiber Substances 0.000 claims description 8
- 238000009987 spinning Methods 0.000 claims description 6
- 239000004744 fabric Substances 0.000 claims description 5
- 230000006872 improvement Effects 0.000 claims description 2
- 238000001914 filtration Methods 0.000 claims 1
- 239000002245 particle Substances 0.000 abstract description 16
- 238000000576 coating method Methods 0.000 abstract description 12
- 239000011248 coating agent Substances 0.000 abstract description 11
- 229920001169 thermoplastic Polymers 0.000 abstract description 10
- 239000004416 thermosoftening plastic Substances 0.000 abstract description 10
- 230000009467 reduction Effects 0.000 abstract description 2
- 210000004379 membrane Anatomy 0.000 description 22
- 239000010410 layer Substances 0.000 description 12
- 238000000034 method Methods 0.000 description 11
- 239000002184 metal Substances 0.000 description 4
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 3
- 239000004743 Polypropylene Substances 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- -1 polypropylene Polymers 0.000 description 2
- 229920001155 polypropylene Polymers 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- 229920000742 Cotton Polymers 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000007767 bonding agent Substances 0.000 description 1
- 238000009960 carding Methods 0.000 description 1
- 229920002301 cellulose acetate Polymers 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000001223 reverse osmosis Methods 0.000 description 1
- 239000011343 solid material Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000000108 ultra-filtration Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/10—Supported membranes; Membrane supports
- B01D69/107—Organic support material
- B01D69/1071—Woven, non-woven or net mesh
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S428/00—Stock material or miscellaneous articles
- Y10S428/903—Microfiber, less than 100 micron diameter
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/26—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/27—Web or sheet containing structurally defined element or component, the element or component having a specified weight per unit area [e.g., gms/sq cm, lbs/sq ft, etc.]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
- Y10T428/2982—Particulate matter [e.g., sphere, flake, etc.]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
- Y10T442/60—Nonwoven fabric [i.e., nonwoven strand or fiber material]
- Y10T442/608—Including strand or fiber material which is of specific structural definition
- Y10T442/609—Cross-sectional configuration of strand or fiber material is specified
- Y10T442/611—Cross-sectional configuration of strand or fiber material is other than circular
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
- Y10T442/60—Nonwoven fabric [i.e., nonwoven strand or fiber material]
- Y10T442/659—Including an additional nonwoven fabric
- Y10T442/673—Including particulate material other than fiber
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Laminated Bodies (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
- Nonwoven Fabrics (AREA)
Abstract
Abstract of the Disclosure A non-woven material which is particularly suitable for backing or supporting a semipermeable membrane at least one surface of which has an open-structured, continuous, calendered coating of fine thermoplastic particles.
The coated non-woven material provides an optimum thin layer thickness independent of the variations in the surface of the material. In addition the coated non-woven material provides savings in cost, a reduction in rejection rate and in particular, semipermeable membranes with improved permeation rates.
The coated non-woven material provides an optimum thin layer thickness independent of the variations in the surface of the material. In addition the coated non-woven material provides savings in cost, a reduction in rejection rate and in particular, semipermeable membranes with improved permeation rates.
Description
1~87~1 This invention relates to a backing for semipermeable membranes.
It is well known that semipermeable membranes, which are used, for example, in installations which operate on the principle of reverse osmosis and ultrafiltration, and take the form e.g. of tubular and flat membranes, are technologically weak and therefore require technological support by a supporting unit. This backing is provided, e.g. by perforated tubes, or by perforated or channeled plates. Since the perforation or channel interval of such backing materials often has to be kept comparatively large for reasons of strength, on account of the high pressures often called for in the processes, a porous mass that is incompressible in operation is used as a drainage layer between the semipermeable membrane and the supporting unit. Normally this drainage layer, hereinafter called the backing, is directly coated with the membrane. It serves both for drainage of the permeate and for the technological support of the sensitive membrane.
For backing purposes the use of non-woven materials manufactured by a dry or a wet method or by a spun non-woven method and which may or may not have been strengthened by hot-calendering, is known. In all non-woven materials of this kind the protrusion of separate ends of fibres or of loops cannot be completely avoided. Because of the still comparatively coarse fibre standard obtainable in the micro region by this method, the surface of the non-woven material is still comparatively rough, even after calendering. Because of the roughness of the backing surface, when coated with a membrane, variations in the thickness of the membrane result, leading to variable membrane properties in the micro region. The protruding fibres give rise to special difficulties in the course of membrane application, inasmuch as the fibres during the coating process are not folded back by the membrane solution and become embedded in it, but protrude more or less from the surface of the non-woven material and thus penetrate into the membrane and may even pierce the active membrane surface which, as is known, is very thin, between 500 and 5,000 angstr~m units. This results in non-uniform, i.e. inadequate permeability properties on the part of the membrane. Since in the applications in which ~9877~
semipermeable membranes of this kind are used, material flaws must generally be excluded, it has been common to increase the thickness of the extruded-on coating of e.g. cellulose acetate far beyond the optimum. This not only re-duced the permeation rate of the membrane, but also considerably increased the manufacturing costs.
The present invention seeks to overcome these problems by providing a backing material with a surface which is substantially free of protruding fibre ends or loops.
Thus the present invention provides a backing for semipermeable mem-branes which comprises a non-woven material having a calendered, open-structured coating of fine thermoplastic particles on at least one surface thereof.
Preferably the supporting non-woven material comprises at least one type of fibre selected from cut and uncut inorganic and organic fibres bonded together thermally or with a bonding agent. Further, the coating preferably consists of particles showered or spun directly onto the surface (or surfaces) of the supporting non-woven material. The particles forming the coating preferably have a diameter of less than 30 X 10 m, more preferably between 1 X 10 m and 20 X 10 m. The particles constituting the coating may include particles whose cross-section may depart from a round profile shape. Further, it is preferred that the weight per unit area of the coating employed lies between 1 and 20 g/m , more preferably between 10 and 40 g/m .
More particularly, the present invention provides a non-woven fabric having a smooth surface, especially for use as a support material for a semi-permeable membrane, comprising a support mat having at least one surface into which there has been calendered an open structured porous covering layer of fine flat fibres having a thickness of less than about 30 X 10 m, the covering layer having a specific welght of about 1 to 200 g/m and having been e -2-~98771 formed by electrostatically spinning the fibres directly onto the support mat, the support mat extending over the entire width of the fabric.
The present invention also includes a method for making a backing for semipermeable membranes which comprises forming a non-woven material by a hydrodynamic method, applying a coating of fine thermoplastic particles to the non-woven material to at least one surface of the material and subjecting the coated material to calendering.
More particularly, the backing of the present invention may be pre-pared by a method which comprises forming a non-woven material by a hydrodynamic method using thermoplastic staple fibres and subjecting the non-woven material to an initial strengthening by a drying process. To the B
~987~1 surface of the non-woven material thus obtained a coating is then applied consisting of fine thermoplastic particles. Preferably, the thermoplastic particles are applied to a surface of the non-woven material via an electro-static spray method as described in Bayer's German Patentschrift 20 32 072 published January 5, 1972 or via spinning directly from a thermoplastic melt onto the surface. As indicated previously it is possible to coat both surfaces of the non-woven material. The thermoplastic particles thus deposited are not necessarily distributed evenly over the material but they tend to fill up any cavities in the surface of the non-woven material so that the coated surface is extremely smooth and evenly coated over its working width. These excellent properties are improved when the coated non-woven material is calendered, preferably heat calendered. The resulting product is extremely smooth and yet still very porous. The thermoplastic particles provide a surface coating on the non-woven material in thicknesses in the range of from 10 to 40 g/m .
Another basic feature of the coated non-woven material lies in the fact that the applied plastic particles often possess a fibrous or strip-like structure, the fibre or strip fineness being at least below 30 x 10 6 m.
As a consequence of this coating of fine thermoplastic particles, an extremely smooth, either shiny or dull surface is provided on the resulting non-woven material in the course of the final calendering, while the non-woven material retains its porous structure. Even in the micro region, the extreme uni-formity and smoothness of the non-woven material surface structure is immediately recognizable.
The special advantage of the coated non-woven material of the invention lies in the fact that it greatly simplifies the application of a membrane solution which constitutes the semipermeable layer since it provides an optimum thin layer thickness independent of the constant variations in the surface of the material. In addition to a surprisingly high saving of costs and a reduction in the rejection rate, and the associated improvement in manufacturing quality, in particular, semipermeable membranes with improved permeation rates can be manufactured.
~9877~
The following examples are included to illustrate the present invention.
Example 1:
From a mixture of 35% by weight of undrawn polyester fibres with a titer of 6.8 dtex and a length of 12 mm as well as 65% by weight of drawn poly-ester fibres with a titer of 1.3 dtex and a length of 12 mm, a watery suspension with a content of solid material of 0.02% by weight was prepared and dehydrated on a screen device similar to a paper machine. After drying at 150 C, a non-woven fabric with a weight per unit area of 90 g/m was obtained which was reinforced by means of heat calendering.
For this purpose, a combined steel/cotton calender was used with each roller having a diameter of 350 mm. The speed is 5 m/min and the linear pressure lS 100 kg/cm and the temperature is 220 C.
Subsequently onto the surface of the thus obtained non-woven fabric a layer of finest fibres was applied by an electrostatical spraying procedure.
As spraying electrodes two counter current metal rings which were moved in a direction transverse to the transportation direction of the non-woven fabric were employed which were continuously wetted with a solution of 10% by weight of polycarbonate in methylene chloride. The distance of the electrode to the surface of the non-woven fabric which was led over a counter electrode is 400 mm. The voltage applied is 150 kV. The speed of the non-woven fabric was adjusted such that on its furface a fibre layer with an average weight per unit area of 40 g/m2 was deposited. In the micro range, this layer did not have an entirely uniform surface, but the uneveness of the surface was equalized and a highly uniform surface of the covering layer was formed.
After a final calendering treatment with the above described calender at a speed of 12 m/min and a linear pressure of 50 kg/cm and a temperature of 120 C, the surface had a brilliant, extremely uniform appearance. Consequently the surface was free of all irregularities. This was a special advantage as surprisingly the porosity substantially corresponded to that of an uncoated - ~98771 non-woven fabric.
Example 2:
On a carding machine using a dry method, a non-woven fabric was form-ed with a weight per unit area of 100 g/m2 consisting of a mixture of 70%
by weight of polypropylene fibres with a titer of 3.3 dtex and a length of 64 mm and 30% by weight of polypropylene fibres with a titer of 2.8 dtex and a length of 60 mm. The fabric was reinforced in the calender of Example 1 at a speed of 20 m/min and a linear pressure of 60 kg/cm at a temperature of 130 C.
Subsequently the non-woven fabric was led through an electrostatical fusion spinning device. This device consisted on one side of a conveyor band out of an open wire network for the non-woven fabric and on the other side of a part of a constantly rotating, endless metal band which was arranged at a right angle to the transportation direction of the non-woven fabric. The metal band was brought to an increased temperature by means of secondary heating devices.
Out of the range of the spinning zone, onto its surface particles of poly-propylene in powder shape were sprinkled, these particles fused and formed a closed film.
As a result of the movement of the metal band into the spinning zone, particles were extracted from this film under the influence of electrostatical forces according to example 1 and were deposited on the surface of the carrier non-woven fabric in the form of fine fibres with an average diameter of O.G15 mm. The transportation speed of the non-woven fabric was ad~usted so that on its furface a layer with an average weight per unit area of 35 g/m was formed.
The surface of the non-woven fabric thus coated was found to be smooth and highly uniform, the cavities and uneveness in the surface having been filled and smoothed out with the coating layer.
The thus obtained coated material was then treated with the calender of Example 1 at a speed of 12 m/min and a linear pressure of 40 kg/cm and a temperature of 130C. The coated material had a brilliant and completely smooth surface and was found to be particularly suited as a carrier layer or backing for a semipermeable membrane.
It is well known that semipermeable membranes, which are used, for example, in installations which operate on the principle of reverse osmosis and ultrafiltration, and take the form e.g. of tubular and flat membranes, are technologically weak and therefore require technological support by a supporting unit. This backing is provided, e.g. by perforated tubes, or by perforated or channeled plates. Since the perforation or channel interval of such backing materials often has to be kept comparatively large for reasons of strength, on account of the high pressures often called for in the processes, a porous mass that is incompressible in operation is used as a drainage layer between the semipermeable membrane and the supporting unit. Normally this drainage layer, hereinafter called the backing, is directly coated with the membrane. It serves both for drainage of the permeate and for the technological support of the sensitive membrane.
For backing purposes the use of non-woven materials manufactured by a dry or a wet method or by a spun non-woven method and which may or may not have been strengthened by hot-calendering, is known. In all non-woven materials of this kind the protrusion of separate ends of fibres or of loops cannot be completely avoided. Because of the still comparatively coarse fibre standard obtainable in the micro region by this method, the surface of the non-woven material is still comparatively rough, even after calendering. Because of the roughness of the backing surface, when coated with a membrane, variations in the thickness of the membrane result, leading to variable membrane properties in the micro region. The protruding fibres give rise to special difficulties in the course of membrane application, inasmuch as the fibres during the coating process are not folded back by the membrane solution and become embedded in it, but protrude more or less from the surface of the non-woven material and thus penetrate into the membrane and may even pierce the active membrane surface which, as is known, is very thin, between 500 and 5,000 angstr~m units. This results in non-uniform, i.e. inadequate permeability properties on the part of the membrane. Since in the applications in which ~9877~
semipermeable membranes of this kind are used, material flaws must generally be excluded, it has been common to increase the thickness of the extruded-on coating of e.g. cellulose acetate far beyond the optimum. This not only re-duced the permeation rate of the membrane, but also considerably increased the manufacturing costs.
The present invention seeks to overcome these problems by providing a backing material with a surface which is substantially free of protruding fibre ends or loops.
Thus the present invention provides a backing for semipermeable mem-branes which comprises a non-woven material having a calendered, open-structured coating of fine thermoplastic particles on at least one surface thereof.
Preferably the supporting non-woven material comprises at least one type of fibre selected from cut and uncut inorganic and organic fibres bonded together thermally or with a bonding agent. Further, the coating preferably consists of particles showered or spun directly onto the surface (or surfaces) of the supporting non-woven material. The particles forming the coating preferably have a diameter of less than 30 X 10 m, more preferably between 1 X 10 m and 20 X 10 m. The particles constituting the coating may include particles whose cross-section may depart from a round profile shape. Further, it is preferred that the weight per unit area of the coating employed lies between 1 and 20 g/m , more preferably between 10 and 40 g/m .
More particularly, the present invention provides a non-woven fabric having a smooth surface, especially for use as a support material for a semi-permeable membrane, comprising a support mat having at least one surface into which there has been calendered an open structured porous covering layer of fine flat fibres having a thickness of less than about 30 X 10 m, the covering layer having a specific welght of about 1 to 200 g/m and having been e -2-~98771 formed by electrostatically spinning the fibres directly onto the support mat, the support mat extending over the entire width of the fabric.
The present invention also includes a method for making a backing for semipermeable membranes which comprises forming a non-woven material by a hydrodynamic method, applying a coating of fine thermoplastic particles to the non-woven material to at least one surface of the material and subjecting the coated material to calendering.
More particularly, the backing of the present invention may be pre-pared by a method which comprises forming a non-woven material by a hydrodynamic method using thermoplastic staple fibres and subjecting the non-woven material to an initial strengthening by a drying process. To the B
~987~1 surface of the non-woven material thus obtained a coating is then applied consisting of fine thermoplastic particles. Preferably, the thermoplastic particles are applied to a surface of the non-woven material via an electro-static spray method as described in Bayer's German Patentschrift 20 32 072 published January 5, 1972 or via spinning directly from a thermoplastic melt onto the surface. As indicated previously it is possible to coat both surfaces of the non-woven material. The thermoplastic particles thus deposited are not necessarily distributed evenly over the material but they tend to fill up any cavities in the surface of the non-woven material so that the coated surface is extremely smooth and evenly coated over its working width. These excellent properties are improved when the coated non-woven material is calendered, preferably heat calendered. The resulting product is extremely smooth and yet still very porous. The thermoplastic particles provide a surface coating on the non-woven material in thicknesses in the range of from 10 to 40 g/m .
Another basic feature of the coated non-woven material lies in the fact that the applied plastic particles often possess a fibrous or strip-like structure, the fibre or strip fineness being at least below 30 x 10 6 m.
As a consequence of this coating of fine thermoplastic particles, an extremely smooth, either shiny or dull surface is provided on the resulting non-woven material in the course of the final calendering, while the non-woven material retains its porous structure. Even in the micro region, the extreme uni-formity and smoothness of the non-woven material surface structure is immediately recognizable.
The special advantage of the coated non-woven material of the invention lies in the fact that it greatly simplifies the application of a membrane solution which constitutes the semipermeable layer since it provides an optimum thin layer thickness independent of the constant variations in the surface of the material. In addition to a surprisingly high saving of costs and a reduction in the rejection rate, and the associated improvement in manufacturing quality, in particular, semipermeable membranes with improved permeation rates can be manufactured.
~9877~
The following examples are included to illustrate the present invention.
Example 1:
From a mixture of 35% by weight of undrawn polyester fibres with a titer of 6.8 dtex and a length of 12 mm as well as 65% by weight of drawn poly-ester fibres with a titer of 1.3 dtex and a length of 12 mm, a watery suspension with a content of solid material of 0.02% by weight was prepared and dehydrated on a screen device similar to a paper machine. After drying at 150 C, a non-woven fabric with a weight per unit area of 90 g/m was obtained which was reinforced by means of heat calendering.
For this purpose, a combined steel/cotton calender was used with each roller having a diameter of 350 mm. The speed is 5 m/min and the linear pressure lS 100 kg/cm and the temperature is 220 C.
Subsequently onto the surface of the thus obtained non-woven fabric a layer of finest fibres was applied by an electrostatical spraying procedure.
As spraying electrodes two counter current metal rings which were moved in a direction transverse to the transportation direction of the non-woven fabric were employed which were continuously wetted with a solution of 10% by weight of polycarbonate in methylene chloride. The distance of the electrode to the surface of the non-woven fabric which was led over a counter electrode is 400 mm. The voltage applied is 150 kV. The speed of the non-woven fabric was adjusted such that on its furface a fibre layer with an average weight per unit area of 40 g/m2 was deposited. In the micro range, this layer did not have an entirely uniform surface, but the uneveness of the surface was equalized and a highly uniform surface of the covering layer was formed.
After a final calendering treatment with the above described calender at a speed of 12 m/min and a linear pressure of 50 kg/cm and a temperature of 120 C, the surface had a brilliant, extremely uniform appearance. Consequently the surface was free of all irregularities. This was a special advantage as surprisingly the porosity substantially corresponded to that of an uncoated - ~98771 non-woven fabric.
Example 2:
On a carding machine using a dry method, a non-woven fabric was form-ed with a weight per unit area of 100 g/m2 consisting of a mixture of 70%
by weight of polypropylene fibres with a titer of 3.3 dtex and a length of 64 mm and 30% by weight of polypropylene fibres with a titer of 2.8 dtex and a length of 60 mm. The fabric was reinforced in the calender of Example 1 at a speed of 20 m/min and a linear pressure of 60 kg/cm at a temperature of 130 C.
Subsequently the non-woven fabric was led through an electrostatical fusion spinning device. This device consisted on one side of a conveyor band out of an open wire network for the non-woven fabric and on the other side of a part of a constantly rotating, endless metal band which was arranged at a right angle to the transportation direction of the non-woven fabric. The metal band was brought to an increased temperature by means of secondary heating devices.
Out of the range of the spinning zone, onto its surface particles of poly-propylene in powder shape were sprinkled, these particles fused and formed a closed film.
As a result of the movement of the metal band into the spinning zone, particles were extracted from this film under the influence of electrostatical forces according to example 1 and were deposited on the surface of the carrier non-woven fabric in the form of fine fibres with an average diameter of O.G15 mm. The transportation speed of the non-woven fabric was ad~usted so that on its furface a layer with an average weight per unit area of 35 g/m was formed.
The surface of the non-woven fabric thus coated was found to be smooth and highly uniform, the cavities and uneveness in the surface having been filled and smoothed out with the coating layer.
The thus obtained coated material was then treated with the calender of Example 1 at a speed of 12 m/min and a linear pressure of 40 kg/cm and a temperature of 130C. The coated material had a brilliant and completely smooth surface and was found to be particularly suited as a carrier layer or backing for a semipermeable membrane.
Claims (4)
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A nonwoven fabric having a smooth surface, especially for use as a support material for a semipermeable membrane, comprising a support mat having at least one surface into which there has been calendered an open structured porous covering layer of fine flat fibers having a thickness of less than about 30 X
10-6 m, the covering layer having a specific weight of about 1 to 200 g/m2 and having been formed by electrostatically spinning the fibers directly onto the support mat, the support mat extending over the entire width of the fabric.
10-6 m, the covering layer having a specific weight of about 1 to 200 g/m2 and having been formed by electrostatically spinning the fibers directly onto the support mat, the support mat extending over the entire width of the fabric.
2. A fabric according to claim 1, wherein the fiber thickness is from about 1 X 10-6 to 20 X 10-6 m.
3. A fabric according to claim 1, wherein the covering layer has a specific weight of about 10 to 40 g/m2.
4. In a system for filtration using a semipermeable membrane, the improvement which comprises using said membrane supported on a nonwoven fabric according to claim 1.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2655024A DE2655024C3 (en) | 1976-12-04 | 1976-12-04 | Carrier layer for a semipermeable membrane |
| DEP2655024.3 | 1976-12-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1098771A true CA1098771A (en) | 1981-04-07 |
Family
ID=5994679
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA292,368A Expired CA1098771A (en) | 1976-12-04 | 1977-12-05 | Backing for semipermeable membrane |
Country Status (14)
| Country | Link |
|---|---|
| US (1) | US4180611A (en) |
| JP (1) | JPS5370987A (en) |
| AT (1) | AT367313B (en) |
| AU (1) | AU512500B2 (en) |
| CA (1) | CA1098771A (en) |
| DE (1) | DE2655024C3 (en) |
| DK (1) | DK148436C (en) |
| ES (1) | ES463359A1 (en) |
| FR (1) | FR2372644A1 (en) |
| GB (1) | GB1582790A (en) |
| IL (1) | IL53456A0 (en) |
| NL (1) | NL184798C (en) |
| SE (1) | SE433507B (en) |
| ZA (1) | ZA776020B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2810702A4 (en) * | 2012-01-30 | 2015-09-02 | Hokuetsu Kishu Paper Co Ltd | Non-woven fabric for semipermeable membrane support |
| EP2821125A4 (en) * | 2012-03-01 | 2015-09-16 | Hokuetsu Kishu Paper Co Ltd | Nonwoven fabric for semipermeable membrane supporting body and method for manufacturing same |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0048110B1 (en) * | 1980-09-11 | 1986-06-11 | United Kingdom Atomic Energy Authority | Selective retention with composite materials |
| GB2134808B (en) * | 1983-01-24 | 1987-08-05 | English Clays Lovering Pochin | Pressure filters |
| GB2169224B (en) * | 1984-12-21 | 1989-01-11 | Pall Corp | Supported microporous membrane and method of making |
| US4774001A (en) * | 1984-12-21 | 1988-09-27 | Pall Corporation | Supported microporous membrane |
| JPS61222506A (en) * | 1985-03-29 | 1986-10-03 | Japan Vilene Co Ltd | Semipermeable membrane support and its preparation |
| US4714647A (en) * | 1986-05-02 | 1987-12-22 | Kimberly-Clark Corporation | Melt-blown material with depth fiber size gradient |
| US4904523A (en) * | 1987-01-06 | 1990-02-27 | Pellon Company | Polyester heat bonded product |
| US5391425A (en) * | 1992-07-30 | 1995-02-21 | Hexcel Corporation | Composite material with shrinkage barrier |
| JP5291274B2 (en) * | 2000-09-22 | 2013-09-18 | 阿波製紙株式会社 | Semipermeable membrane support and method for producing a semipermeable membrane using the same |
| DE102007042554B4 (en) * | 2007-09-07 | 2017-05-11 | Carl Freudenberg Kg | Nonwoven with particle filling |
| JP5447395B2 (en) * | 2008-02-20 | 2014-03-19 | カール・フロイデンベルク・カー・ゲー | Fleece cloth containing cross-linked material |
Family Cites Families (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB776179A (en) * | 1954-09-24 | 1957-06-05 | Celanese Corp | Plastic laminates |
| US3102836A (en) * | 1959-10-20 | 1963-09-03 | United Shoe Machinery Corp | Sheet material comprising fibers and plastic particles |
| US2992149A (en) * | 1960-03-23 | 1961-07-11 | Chicopee Mfg Corp | Heat-sealable sheet materials |
| NL6403128A (en) * | 1963-10-31 | 1965-05-03 | ||
| US3503784A (en) * | 1965-10-15 | 1970-03-31 | Kuraray Co | Smooth surfaced sheet materials and method of manufacturing the same |
| GB1159997A (en) * | 1966-08-23 | 1969-07-30 | August Ferdinand Junio Schramm | Processes of Making Flexbiel Air-Permeable Sheet Products |
| GB1241973A (en) * | 1968-07-30 | 1971-08-11 | American Standard Inc | Improvements in or relating to supporting osmotic membranes |
| NL7102636A (en) * | 1971-02-26 | 1972-08-29 | Reverse osmosis appts - with open celled synthetic resin layer between cellulose acetate membrane and plastic support tube | |
| US3762566A (en) * | 1971-08-03 | 1973-10-02 | Abcor Inc | Supported semipermeable membranes and process for preparing same |
| DE2305693A1 (en) * | 1972-02-07 | 1973-08-16 | Ici Ltd | NON-WOVEN STRUCTURE |
| US3837995A (en) * | 1972-04-24 | 1974-09-24 | Kimberly Clark Co | Autogenously bonded composite web |
| FR2194461B1 (en) * | 1972-06-23 | 1975-03-07 | Rhone Poulenc Ind | |
| US3878014A (en) * | 1973-04-30 | 1975-04-15 | Beloit Corp | Process for matting melt blow microfibers |
| US3914358A (en) * | 1973-12-10 | 1975-10-21 | Westinghouse Electric Corp | Method of improving the finish of the bores of a reverse osmosis sand module |
| US3949130A (en) * | 1974-01-04 | 1976-04-06 | Tuff Spun Products, Inc. | Spun bonded fabric, and articles made therefrom |
-
1976
- 1976-12-04 DE DE2655024A patent/DE2655024C3/en not_active Expired
-
1977
- 1977-10-07 ZA ZA00776020A patent/ZA776020B/en unknown
- 1977-10-19 ES ES463359A patent/ES463359A1/en not_active Expired
- 1977-10-20 AU AU29899/77A patent/AU512500B2/en not_active Expired
- 1977-11-03 NL NLAANVRAGE7712122,A patent/NL184798C/en not_active IP Right Cessation
- 1977-11-11 JP JP13484477A patent/JPS5370987A/en active Granted
- 1977-11-23 IL IL53456A patent/IL53456A0/en not_active IP Right Cessation
- 1977-12-01 US US05/856,564 patent/US4180611A/en not_active Expired - Lifetime
- 1977-12-01 SE SE7713647A patent/SE433507B/en not_active IP Right Cessation
- 1977-12-02 GB GB50216/77A patent/GB1582790A/en not_active Expired
- 1977-12-02 FR FR7736384A patent/FR2372644A1/en active Granted
- 1977-12-02 DK DK539777A patent/DK148436C/en not_active IP Right Cessation
- 1977-12-02 AT AT0865877A patent/AT367313B/en not_active IP Right Cessation
- 1977-12-05 CA CA292,368A patent/CA1098771A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2810702A4 (en) * | 2012-01-30 | 2015-09-02 | Hokuetsu Kishu Paper Co Ltd | Non-woven fabric for semipermeable membrane support |
| EP2821125A4 (en) * | 2012-03-01 | 2015-09-16 | Hokuetsu Kishu Paper Co Ltd | Nonwoven fabric for semipermeable membrane supporting body and method for manufacturing same |
Also Published As
| Publication number | Publication date |
|---|---|
| SE433507B (en) | 1984-05-28 |
| FR2372644B1 (en) | 1984-09-14 |
| ES463359A1 (en) | 1978-07-16 |
| DE2655024B2 (en) | 1981-06-04 |
| DE2655024A1 (en) | 1978-06-08 |
| NL7712122A (en) | 1978-06-06 |
| DK148436B (en) | 1985-07-08 |
| DK148436C (en) | 1986-03-03 |
| AU2989977A (en) | 1979-04-26 |
| IL53456A0 (en) | 1978-01-31 |
| FR2372644A1 (en) | 1978-06-30 |
| SE7713647L (en) | 1978-06-05 |
| JPS5370987A (en) | 1978-06-23 |
| DK539777A (en) | 1978-06-05 |
| ZA776020B (en) | 1978-05-30 |
| US4180611A (en) | 1979-12-25 |
| DE2655024C3 (en) | 1982-04-22 |
| GB1582790A (en) | 1981-01-14 |
| NL184798C (en) | 1989-11-01 |
| ATA865877A (en) | 1981-11-15 |
| AT367313B (en) | 1982-06-25 |
| AU512500B2 (en) | 1980-10-16 |
| JPS6158203B2 (en) | 1986-12-10 |
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Legal Events
| Date | Code | Title | Description |
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| MKEX | Expiry |