CA1107580A - Non-woven material for support of semipermeable membrane - Google Patents
Non-woven material for support of semipermeable membraneInfo
- Publication number
- CA1107580A CA1107580A CA292,431A CA292431A CA1107580A CA 1107580 A CA1107580 A CA 1107580A CA 292431 A CA292431 A CA 292431A CA 1107580 A CA1107580 A CA 1107580A
- Authority
- CA
- Canada
- Prior art keywords
- fibres
- bonding
- bonding fibres
- woven material
- dtex
- 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
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
-
- 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
-
- D—TEXTILES; PAPER
- D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
- D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
- D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
- D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
- D04H1/54—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by welding together the fibres, e.g. by partially melting or dissolving
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H5/00—Special paper or cardboard not otherwise provided for
- D21H5/12—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials
- D21H5/20—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials of organic non-cellulosic fibres too short for spinning, with or without cellulose fibres
Abstract
Abstract of the Disclosure A non-woven material and a method for making it, for use as a backing for a semipermeable membrane which comprises binding fibres, the distribution of which corresponds to that of a wet-laid non-woven material, the binding fibres being fused and flattened, without restriction of the porosity of the material in the surface region of the material.
Description
11~7S~
The invention relates to a non-woven material for the support of a semipermeable membrane.
Semipermeable membranes are known to be technologically weak and therefore require technological backing by a supporting element.
They are used, for example, in installations which operate on the principle of reverse osmosis and ultrafiltration. They are supported, for example, by perforated pipes or plates, i.e. porous and comparatively pressure-resistant supporting materials, for example in the form of PVC or fine steel pipes, or slabs of plastic. Since the perforation or channel interval of such support-ing materials, on account of the pressures often made necessary by the processesinvolved, e.g. 1-140 bar~ must be kept fairly high for reasons of technological strength, a mass that is non-compressible during operation is used as a drain-age backing layer between the semipermeable membrane and the supporting element.
The most common semipermeable membranes are made of cellulose acetate. The cellulose acetate is applied by extrusion in a fluid state to a porous non-woven backing fabric in a layer thickness of about 100 to 200 ~m. During this coating procedure, the underside surface of the cellulose acetate layer assumes all the irregularities of the surface of the non-woven fabric which produces variations in the thickness of the cellulose acetate layer. These variations are subsequently translated to the semi-permeable membrane which is formed on the surface of the cellulose acetate layer. The variations in the thickness of the semipermeable layer results in differences in the filtering properties of the final product. Thus there is a need to provide a non-woven backing material which has a very smooth surface in the micro range.
; The cellulose acetate layer has a thickness in the range of 0.1 to 0.2 mm. Therefore, cross drainage of fluids which have penetrated into its surface cannot be expected. In order to obtain a low passing resistance in spite of this fact, it is necessary that the non-woven fabric employed as the carrier or backing material have a high porosity. After subsequent coagulation of the cellulose acetate layer, the active membrane s~
~roper is formed on this backing in a thlckness of 500 to 5,000 angstrom units.
The use of backings made from flat textile materials, for example fabric, paper or non-woven material is already well known. So far, the results obtained in this way have not been satisfactory. Great difficult-ies arise owing to the unavoidable irregularities in the micro region in such materials. In the case of fabrics, their structure was frequently reflected on the surface of the highly sensitive membrane, and this could result in hairline cracks and eventual destruction of the membrane.
Cellulose-based papers have poor technological strength properties, and in the course of use are bacterially destroyed in a comparatively short time. Papers of 100% synthetic composition with the necessary high technological strength properties cannot be produced according to methods known in the present state of the art.
For this reason the use of non-woven material has been adopted. Non-woven materials of 100% synthetic, thermoplastic fibres, pre-ferably polyester or polypropylene fibres produced by a dry method, e.g. by teaseling or carding and strengthening in an essentially known manner by the application of heat and pressure, have thus far proved the most suitable.
Such non-woven materials have extremely high wet strength properties.
A basic disadvantage of these dry-manufactured non-wovens, however, is the lack of uniformity in their non-woven pattern, i.e. an inade-quate distribution of individual fibres, together with a roughness of surface.
In transversely laid non-wovens, moreover, there is an uneven weight and thickness distribution over the production width.
A certain improvement in the weight and thickness distribution has been achieved by combining transversely and longitudinally laid non-woven materials and calendering the materials. Even so, however, a certain lack of uniformity remains over the production width, especially higher weights and smaller thicknesses in the edge zones compared with the centre zone of the non-woven material. This lack of uniformity of the non-woven material results in a lack of uniformity of the membrane thickness when the non-woven material is subsequently coated with the membrane 75~
~, solution so that irregular membrane properties are obtained. Since these irregular membrane properties are unacceptable, comparatively wide edge ~ones have hitherto had to be discarded before or after coating with the membrane.
This leads, of course, to a substantial increase in the total cost of membrane production.
Aerodynamically laid non-woven or spun non-woven materials have greater uniformity, to be sure, as far as their weight and thickness distribution over the production width is concerned. However, their comparatively irregular non-woven pattern owing to an irregular individual fibre scattering or individual fibre distribution, again leads to comparatively irregular membrane thicknesses when the non-woven material is subsequently \ coated with the membrane solution, and hence to comparatively irregular membrane properties.
Difficulties of the kind described have been difficult to avoid owing to the specific characteristics of known textiles. Control operations that were difficult to execute, as well as an extremely high rate -of rejection, therefore have to be accepted and.result in an extreme increase in the cost of these membranes.
The present invention seeks to develop a physiologically unobjectionable backing, which is chemically, physically and thermally resistant to a high degree and which avoids the aforementioned disadvantages and would ensure the production of a semiper~eable membrane with excellent uniformity by a comparatively simple manufacturing process.
Thus the present invention provides a non-woven material for use as a backing for a semipermeable membrane which comprises bonding fibres, the distribution of which corresponds to that of a wet-laid non-woven material, the bonding fibres being fused and flattened, without restriction of the porosity of the material in the surface region of the material.
The non-woven material of the present invention has fibres which are oriented in the same way as those of a wet laid non-woven material and are thermoplastically bonded and progressively compacted without restrict-ing the porosity in the surface region.
B
.
11~75~
Th~s the present invention provides a permeable, bonded, non-woven material for use as a carrier for a semi-permeable membrane, comprising a calandered, wet-laid mixture of thermoplastic bonding fibres of size 4 to 30 dtex and optionally non-bonding fibres of size 1 to 7 dtex, and the top surface of the material being comprised substantially of bonding fibres which provide a smooth, highly porous upper surface layer.
~3 75~3~
According to a special development, provision is made to strengthen the backing by the use of a thermoplastic bonding agent in the form of thermoplastic bonding fibres, which may or may not be blended with nn-bonding fibres. The bonding fibres have a cut length between 6 mm and 36 mm, preferably 12 mm, and the non-bonding fibres a cut length between 3 mm and 18 mm, preferably 6 mm. The thickness of the bonding fibres employed is preferably between 4 - 30 dtex, preferably 6.8 dtex, that of any non-bonding fibres used between 1 and 7 dtex, preferably between 1.3 and 3.3 dtex. The term dtex is an international unit which measures the weight in grams of a fibre which is 10,000 m. long. The term is a synonym for the thickness of the fibre. The backing consists preferably of 10 to 100% by weight bonding fibres and 90 to 0% by weight non-bonding fibres. As bonding fibres unstretched polyester fibres and/or polypropylene fibres are especially suitable.
The desired use properties can be modified in a quite special way by the specific properties of the non-bonding fibres added. Stretched polyester fibres and/or polyamidimide fibres and/or fibres of aromatic polyamides have proved particularly suitable.
The present invention also provides a method for making a non-woven material for use as a backing for a semipermeable membrane which comprises suspending in aqueous medium a mixture of non-bonding fibres and bonding fibres, dewatering the suspension on a screen to obtain a non-woven material in which the fibres are uniformly distrihuted with the bonding fibres lying on the top surface of the material and calendering the non-woven material at a temperature and a pressure whereby the bonding fibres are fused and flattened.
As indicated previously, the bonding fibres comprise from 10 to 100 parts by weight and the non~bonding fibres comprise from 0 to 90 parts by weight of the non-woven material, the non-bonding fibres being relatively thinner and shorter than the relatively coarse bonding fibres. This difference in the fibre size results in the distribution of the fibres on the screen during dewatering described previously.
r~ ~
=w ~' ~ 75~
Parallel to the surface of the non-woven fabric, all fibres have an almost uniform distribution. Directional effects as they are normally found in dry laid non-woven fabrics are not found in the fabrics of this invention.
After the dewatering step is completed, the resulting non-woven fabric possesses an extremely smooth surface. This smoothness is further increased by submitting the non-woven fabric to a heat calendering process. As indicated above, this calendering process results in the binding fibres at the surface of the fabric fusing. This fusing results in a rein-forcement of the non-woven fabric. ~owever, the basic structure of the individual fibres is not destroyed, and on microscopical examination, the original distribution of the individual fibres is still visible. Only the surface of the abric has been flattened.
The selection o the calendering conditions is readily determined by a person skilled in the art. The desired result is readily ~-apparent from an examination of the surface of the non-woven fabric.
The method of the present invention produces a non-woven fabric which has in the micro range thickness variations of less than + 1%.
Preferably the non-woven bac~ing material is manufactured by the method of this invention in a layer thickness of, for example, 150 x 10 6 m. The uniformity of w2ight and thickness distribution over the production width of the non-woven fabric is substantially better than that of a non-woven fabric produced by the previously described methods. The non-woven patterns, i.e. individual fibre arrangement and individual fibre distribution, are substantially better with the method of this invention than with a dry laid method. The surface of the non-woven material obtained by this method is ~ ~-substantially smoother than the surface of a dry laid non-woven material. .
The resulting non-woven material has a very high isotropic strength which has been found to be of great importance for most applications in the manufacture of semipermeable membranes.
The following example is used to illustrate the present invention.
.
5^
75~!~
Example 1 A mixture of 75% by weight of undrawn fibres having a titre thickness of 6.8 dtex and a length of 12 mm with 25% by weight of drawn polyester fibres having a titre thickness of 1.8 dtex and a length of 6 mm was suspended in water.
The content of solid material was 0.8% by weight. The so formed suspension was led to a screen device similar to a paper machine and once again diluted in the head box with water so that the content of solid material was reduced to 0.2% by weight. The water was drawn off by applying a vacuum to the under-side of the screen and the speed was adJusted so that a non-woven fabric having a weight per unit area of 175 g/m with a moisture content of 85% by weight was deposited thereon. The excessive water was removed from the non-woven fabric by means of a vacuum rotary drier. Air was passed through at a temperature of 140 C until a moisture value of 40% was obtained. Immediately thereafter, the non-woven fabric was submitted to a calender treatment with a calender consisting of a steel and a cotton roller having a diameter of 350 mm each, the surface of the non-woven fabric containing the binding fibres abutting the surface of the steel roller. The calendering was carried out at a temperat-ure of 200 C with a linear pressure of 130 kg/cm and a speed of 3.5 m/min. The resulting non-woven fabric was found to have a surface which was extremely ~` 20 smooth and free of projecting fibre ends or slings.
,''
The invention relates to a non-woven material for the support of a semipermeable membrane.
Semipermeable membranes are known to be technologically weak and therefore require technological backing by a supporting element.
They are used, for example, in installations which operate on the principle of reverse osmosis and ultrafiltration. They are supported, for example, by perforated pipes or plates, i.e. porous and comparatively pressure-resistant supporting materials, for example in the form of PVC or fine steel pipes, or slabs of plastic. Since the perforation or channel interval of such support-ing materials, on account of the pressures often made necessary by the processesinvolved, e.g. 1-140 bar~ must be kept fairly high for reasons of technological strength, a mass that is non-compressible during operation is used as a drain-age backing layer between the semipermeable membrane and the supporting element.
The most common semipermeable membranes are made of cellulose acetate. The cellulose acetate is applied by extrusion in a fluid state to a porous non-woven backing fabric in a layer thickness of about 100 to 200 ~m. During this coating procedure, the underside surface of the cellulose acetate layer assumes all the irregularities of the surface of the non-woven fabric which produces variations in the thickness of the cellulose acetate layer. These variations are subsequently translated to the semi-permeable membrane which is formed on the surface of the cellulose acetate layer. The variations in the thickness of the semipermeable layer results in differences in the filtering properties of the final product. Thus there is a need to provide a non-woven backing material which has a very smooth surface in the micro range.
; The cellulose acetate layer has a thickness in the range of 0.1 to 0.2 mm. Therefore, cross drainage of fluids which have penetrated into its surface cannot be expected. In order to obtain a low passing resistance in spite of this fact, it is necessary that the non-woven fabric employed as the carrier or backing material have a high porosity. After subsequent coagulation of the cellulose acetate layer, the active membrane s~
~roper is formed on this backing in a thlckness of 500 to 5,000 angstrom units.
The use of backings made from flat textile materials, for example fabric, paper or non-woven material is already well known. So far, the results obtained in this way have not been satisfactory. Great difficult-ies arise owing to the unavoidable irregularities in the micro region in such materials. In the case of fabrics, their structure was frequently reflected on the surface of the highly sensitive membrane, and this could result in hairline cracks and eventual destruction of the membrane.
Cellulose-based papers have poor technological strength properties, and in the course of use are bacterially destroyed in a comparatively short time. Papers of 100% synthetic composition with the necessary high technological strength properties cannot be produced according to methods known in the present state of the art.
For this reason the use of non-woven material has been adopted. Non-woven materials of 100% synthetic, thermoplastic fibres, pre-ferably polyester or polypropylene fibres produced by a dry method, e.g. by teaseling or carding and strengthening in an essentially known manner by the application of heat and pressure, have thus far proved the most suitable.
Such non-woven materials have extremely high wet strength properties.
A basic disadvantage of these dry-manufactured non-wovens, however, is the lack of uniformity in their non-woven pattern, i.e. an inade-quate distribution of individual fibres, together with a roughness of surface.
In transversely laid non-wovens, moreover, there is an uneven weight and thickness distribution over the production width.
A certain improvement in the weight and thickness distribution has been achieved by combining transversely and longitudinally laid non-woven materials and calendering the materials. Even so, however, a certain lack of uniformity remains over the production width, especially higher weights and smaller thicknesses in the edge zones compared with the centre zone of the non-woven material. This lack of uniformity of the non-woven material results in a lack of uniformity of the membrane thickness when the non-woven material is subsequently coated with the membrane 75~
~, solution so that irregular membrane properties are obtained. Since these irregular membrane properties are unacceptable, comparatively wide edge ~ones have hitherto had to be discarded before or after coating with the membrane.
This leads, of course, to a substantial increase in the total cost of membrane production.
Aerodynamically laid non-woven or spun non-woven materials have greater uniformity, to be sure, as far as their weight and thickness distribution over the production width is concerned. However, their comparatively irregular non-woven pattern owing to an irregular individual fibre scattering or individual fibre distribution, again leads to comparatively irregular membrane thicknesses when the non-woven material is subsequently \ coated with the membrane solution, and hence to comparatively irregular membrane properties.
Difficulties of the kind described have been difficult to avoid owing to the specific characteristics of known textiles. Control operations that were difficult to execute, as well as an extremely high rate -of rejection, therefore have to be accepted and.result in an extreme increase in the cost of these membranes.
The present invention seeks to develop a physiologically unobjectionable backing, which is chemically, physically and thermally resistant to a high degree and which avoids the aforementioned disadvantages and would ensure the production of a semiper~eable membrane with excellent uniformity by a comparatively simple manufacturing process.
Thus the present invention provides a non-woven material for use as a backing for a semipermeable membrane which comprises bonding fibres, the distribution of which corresponds to that of a wet-laid non-woven material, the bonding fibres being fused and flattened, without restriction of the porosity of the material in the surface region of the material.
The non-woven material of the present invention has fibres which are oriented in the same way as those of a wet laid non-woven material and are thermoplastically bonded and progressively compacted without restrict-ing the porosity in the surface region.
B
.
11~75~
Th~s the present invention provides a permeable, bonded, non-woven material for use as a carrier for a semi-permeable membrane, comprising a calandered, wet-laid mixture of thermoplastic bonding fibres of size 4 to 30 dtex and optionally non-bonding fibres of size 1 to 7 dtex, and the top surface of the material being comprised substantially of bonding fibres which provide a smooth, highly porous upper surface layer.
~3 75~3~
According to a special development, provision is made to strengthen the backing by the use of a thermoplastic bonding agent in the form of thermoplastic bonding fibres, which may or may not be blended with nn-bonding fibres. The bonding fibres have a cut length between 6 mm and 36 mm, preferably 12 mm, and the non-bonding fibres a cut length between 3 mm and 18 mm, preferably 6 mm. The thickness of the bonding fibres employed is preferably between 4 - 30 dtex, preferably 6.8 dtex, that of any non-bonding fibres used between 1 and 7 dtex, preferably between 1.3 and 3.3 dtex. The term dtex is an international unit which measures the weight in grams of a fibre which is 10,000 m. long. The term is a synonym for the thickness of the fibre. The backing consists preferably of 10 to 100% by weight bonding fibres and 90 to 0% by weight non-bonding fibres. As bonding fibres unstretched polyester fibres and/or polypropylene fibres are especially suitable.
The desired use properties can be modified in a quite special way by the specific properties of the non-bonding fibres added. Stretched polyester fibres and/or polyamidimide fibres and/or fibres of aromatic polyamides have proved particularly suitable.
The present invention also provides a method for making a non-woven material for use as a backing for a semipermeable membrane which comprises suspending in aqueous medium a mixture of non-bonding fibres and bonding fibres, dewatering the suspension on a screen to obtain a non-woven material in which the fibres are uniformly distrihuted with the bonding fibres lying on the top surface of the material and calendering the non-woven material at a temperature and a pressure whereby the bonding fibres are fused and flattened.
As indicated previously, the bonding fibres comprise from 10 to 100 parts by weight and the non~bonding fibres comprise from 0 to 90 parts by weight of the non-woven material, the non-bonding fibres being relatively thinner and shorter than the relatively coarse bonding fibres. This difference in the fibre size results in the distribution of the fibres on the screen during dewatering described previously.
r~ ~
=w ~' ~ 75~
Parallel to the surface of the non-woven fabric, all fibres have an almost uniform distribution. Directional effects as they are normally found in dry laid non-woven fabrics are not found in the fabrics of this invention.
After the dewatering step is completed, the resulting non-woven fabric possesses an extremely smooth surface. This smoothness is further increased by submitting the non-woven fabric to a heat calendering process. As indicated above, this calendering process results in the binding fibres at the surface of the fabric fusing. This fusing results in a rein-forcement of the non-woven fabric. ~owever, the basic structure of the individual fibres is not destroyed, and on microscopical examination, the original distribution of the individual fibres is still visible. Only the surface of the abric has been flattened.
The selection o the calendering conditions is readily determined by a person skilled in the art. The desired result is readily ~-apparent from an examination of the surface of the non-woven fabric.
The method of the present invention produces a non-woven fabric which has in the micro range thickness variations of less than + 1%.
Preferably the non-woven bac~ing material is manufactured by the method of this invention in a layer thickness of, for example, 150 x 10 6 m. The uniformity of w2ight and thickness distribution over the production width of the non-woven fabric is substantially better than that of a non-woven fabric produced by the previously described methods. The non-woven patterns, i.e. individual fibre arrangement and individual fibre distribution, are substantially better with the method of this invention than with a dry laid method. The surface of the non-woven material obtained by this method is ~ ~-substantially smoother than the surface of a dry laid non-woven material. .
The resulting non-woven material has a very high isotropic strength which has been found to be of great importance for most applications in the manufacture of semipermeable membranes.
The following example is used to illustrate the present invention.
.
5^
75~!~
Example 1 A mixture of 75% by weight of undrawn fibres having a titre thickness of 6.8 dtex and a length of 12 mm with 25% by weight of drawn polyester fibres having a titre thickness of 1.8 dtex and a length of 6 mm was suspended in water.
The content of solid material was 0.8% by weight. The so formed suspension was led to a screen device similar to a paper machine and once again diluted in the head box with water so that the content of solid material was reduced to 0.2% by weight. The water was drawn off by applying a vacuum to the under-side of the screen and the speed was adJusted so that a non-woven fabric having a weight per unit area of 175 g/m with a moisture content of 85% by weight was deposited thereon. The excessive water was removed from the non-woven fabric by means of a vacuum rotary drier. Air was passed through at a temperature of 140 C until a moisture value of 40% was obtained. Immediately thereafter, the non-woven fabric was submitted to a calender treatment with a calender consisting of a steel and a cotton roller having a diameter of 350 mm each, the surface of the non-woven fabric containing the binding fibres abutting the surface of the steel roller. The calendering was carried out at a temperat-ure of 200 C with a linear pressure of 130 kg/cm and a speed of 3.5 m/min. The resulting non-woven fabric was found to have a surface which was extremely ~` 20 smooth and free of projecting fibre ends or slings.
,''
Claims (20)
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A permeable, bonded, non-woven material for use as a carrier for a smipermeable membrane, comprising a calandered, wet-laid mixture of thermo-plastic bonding fibres of size 4 to 30 dtex and optionally non-bonding fibres of size 1 to 7 dtex, and the top surface of the material being comprised sub-stantially of bonding fibres which provide a smooth highly porous upper surface layer.
2. A non-woven material as claimed in claim 1 wherein from 10 to 100% by weight of bonding fibres and from 90 to 0% by weight of non-bonding fibres are present in the material.
3. A non-woven material as claimed in claim 1 wherein the bonding fibres are selected from unstretched polyester fibres, unstretched polypropylene fibres and mixtures of both.
4. A non-woven material as claimed in claim 1 wherein the non-bonding fibres are selected from the stretched polyester fibres, polyamidimide, aromatic poly-amide fibres and mixtures thereof.
5. A non-woven material as claimed in claim 1 or 2 wherein the bonding fibres have a cut length between 6 and 36 mm.
6. A non-woven material as claimed in claim 1 or 2 wherein the bonding fibres have a cut length of 12 mm.
7. A non-woven material as claimed in claim 1 or 2 wherein the non-bonding fibres have a cut length between 3 and 18 mm.
8. A non-woven material as claimed in claim 1 or 2 wherein the non-bonding fibres have a cut length of 6 mm.
9. A non-woven material as claimed in claim 1 or 2 wherein the bonding fibres have a thickness of 6.8 dtex.
10. A non-woven material as claimed in claim 1 or 2 wherein the non-bonding fibres have a thickness of 1.3 to 3.3 dtex.
11. A method for making a non-woven material for use as a backing for a semipermeable membrane which comprises suspending in aqueous medium bonding fibres of size 4 to 30 dtex and optionally non-bonding fibres of size 1 to 7 dtex, de-watering the suspension on a screen to obtain a non-woven material in which the fibres are uniformly distributed, with the bonding fibres lying on the top sur-face of the material, and calandering the non-woven material at a temperature and a pressure whereby the bonding fibres are fused and flattened, without restriction of the porosity of the material, in the surface region of the material.
12. A method as claimed in claim 11 wherein a mixture of from 10 to 100%
by weight of bonding fibres and from 90 to 0% by weight of non-bonding fibres are suspended in the aqueous medium.
by weight of bonding fibres and from 90 to 0% by weight of non-bonding fibres are suspended in the aqueous medium.
13. A method as claimed in claim 11 wherein the bonding fibres are selected from unstretched polyester fibres, unstretched polypropylene fibres and mixtures of both.
14. A method as claimed in claim 11 wherein the non-bonding fibres are selected from stretched fibres, polyamidimide, aromatic polyamide fibres and mixtures thereof.
15. A method as claimed in claim 11 or 12 wherein the bonding fibres have a cut length between 6 mm and 36 mm.
16. A method as claimed in claim 11 or 12 wherein the bonding fibres have a cut length of 12 mm.
17. A method as claimed in claim 11 or 12 wherein the non-bonding fibres have a cut length between 3 and 18 mm.
18. A method as claimed in claim 11 or 12 wherein the non-bonding fibres have a cut length of 6 mm.
19. A method as claimed in claim 11 or 12 wherein the bonding fibres have a titer of 6.8 dtex.
20. A method as claimed in claim 11 or 12 wherein the non-bonding fibres have a titer of 1.3 to 3.3 dtex.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2655014A DE2655014C3 (en) | 1976-12-04 | 1976-12-04 | Carrier layer for semi-permeable membranes |
| DEP2655014.1 | 1976-12-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1107580A true CA1107580A (en) | 1981-08-25 |
Family
ID=5994671
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA292,431A Expired CA1107580A (en) | 1976-12-04 | 1977-12-05 | Non-woven material for support of semipermeable membrane |
Country Status (12)
| Country | Link |
|---|---|
| JP (1) | JPS5370986A (en) |
| AT (1) | AT367312B (en) |
| AU (1) | AU516289B2 (en) |
| CA (1) | CA1107580A (en) |
| DE (1) | DE2655014C3 (en) |
| DK (1) | DK148786C (en) |
| FR (1) | FR2372922A1 (en) |
| GB (1) | GB1595299A (en) |
| IL (1) | IL53455A0 (en) |
| NL (1) | NL185163C (en) |
| SE (1) | SE433505B (en) |
| ZA (1) | ZA776021B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5417383A (en) * | 1977-07-11 | 1979-02-08 | Toray Ind Inc | Separating unit for liquid |
| JPS61222506A (en) * | 1985-03-29 | 1986-10-03 | Japan Vilene Co Ltd | Semipermeable membrane support and its preparation |
| EP0253047A1 (en) * | 1986-07-14 | 1988-01-20 | VOGELBUSCH GESELLSCHAFT m.b.H. | Membrane-separation element |
| DE3729567A1 (en) * | 1986-09-11 | 1988-03-17 | Kendall & Co | BATTERY CUTTER MATERIAL |
| WO1998004233A1 (en) * | 1996-07-31 | 1998-02-05 | The Procter & Gamble Company | Conditioning shampoo compositions comprising polyalkoxylated polyalkyleneamine |
| WO2012090874A1 (en) * | 2010-12-27 | 2012-07-05 | 北越紀州製紙株式会社 | Wet-laid nonwoven fabric for semipermeable membrane supporting body, method for producing said wet-laid nonwoven fabric, and method for identifying low-density defect of wet-laid nonwoven fabric |
| JP5216924B1 (en) * | 2012-01-30 | 2013-06-19 | 北越紀州製紙株式会社 | Nonwoven fabric for semipermeable membrane support |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1137457A (en) * | 1954-08-07 | 1957-05-29 | Process for the manufacture of papers and films starting from polyolefins | |
| GB1099534A (en) * | 1965-05-26 | 1968-01-17 | Ici Ltd | Fibrous, non-woven sheet materials |
-
1976
- 1976-12-04 DE DE2655014A patent/DE2655014C3/en not_active Expired
-
1977
- 1977-10-07 ZA ZA00776021A patent/ZA776021B/en unknown
- 1977-11-03 NL NLAANVRAGE7712123,A patent/NL185163C/en not_active IP Right Cessation
- 1977-11-11 JP JP13484377A patent/JPS5370986A/en active Pending
- 1977-11-23 IL IL53455A patent/IL53455A0/en not_active IP Right Cessation
- 1977-12-01 SE SE7713646A patent/SE433505B/en not_active IP Right Cessation
- 1977-12-02 AU AU31173/77A patent/AU516289B2/en not_active Expired
- 1977-12-02 FR FR7736383A patent/FR2372922A1/en active Granted
- 1977-12-02 DK DK539877A patent/DK148786C/en active
- 1977-12-02 GB GB50215/77A patent/GB1595299A/en not_active Expired
- 1977-12-02 AT AT0865777A patent/AT367312B/en not_active IP Right Cessation
- 1977-12-05 CA CA292,431A patent/CA1107580A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FR2372922A1 (en) | 1978-06-30 |
| DE2655014C3 (en) | 1979-09-06 |
| FR2372922B1 (en) | 1982-04-09 |
| AT367312B (en) | 1982-06-25 |
| NL7712123A (en) | 1978-06-06 |
| DE2655014A1 (en) | 1978-06-08 |
| SE433505B (en) | 1984-05-28 |
| IL53455A0 (en) | 1978-01-31 |
| SE7713646L (en) | 1978-06-05 |
| NL185163B (en) | 1989-09-01 |
| AU516289B2 (en) | 1981-05-28 |
| DE2655014B2 (en) | 1979-01-04 |
| JPS5370986A (en) | 1978-06-23 |
| ATA865777A (en) | 1981-11-15 |
| DK148786C (en) | 1986-03-03 |
| DK539877A (en) | 1978-06-05 |
| DK148786B (en) | 1985-09-30 |
| NL185163C (en) | 1990-02-01 |
| AU3117377A (en) | 1979-06-07 |
| ZA776021B (en) | 1978-05-30 |
| GB1595299A (en) | 1981-08-12 |
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