GB2172020A - Improvements in and relating to filters - Google Patents

Improvements in and relating to filters Download PDF

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Publication number
GB2172020A
GB2172020A GB08605411A GB8605411A GB2172020A GB 2172020 A GB2172020 A GB 2172020A GB 08605411 A GB08605411 A GB 08605411A GB 8605411 A GB8605411 A GB 8605411A GB 2172020 A GB2172020 A GB 2172020A
Authority
GB
United Kingdom
Prior art keywords
filter means
fibre
fibres
shrinkage
fibre mass
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.)
Granted
Application number
GB08605411A
Other versions
GB8605411D0 (en
GB2172020B (en
Inventor
Prof Dr Klaus Fischer
Dr Leonidas Weibmann
Bernd Steiger
Prof Dr Eberhard Heidenreich
Dr Reiner Tittel
Peter Bohme
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Filmfabrik Wolfen VEB
Original Assignee
Filmfabrik Wolfen VEB
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Filmfabrik Wolfen VEB filed Critical Filmfabrik Wolfen VEB
Publication of GB8605411D0 publication Critical patent/GB8605411D0/en
Publication of GB2172020A publication Critical patent/GB2172020A/en
Application granted granted Critical
Publication of GB2172020B publication Critical patent/GB2172020B/en
Expired legal-status Critical Current

Links

Classifications

    • 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
    • D04H1/44—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 the fleeces or layers being consolidated by mechanical means, e.g. by rolling
    • D04H1/46—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 the fleeces or layers being consolidated by mechanical means, e.g. by rolling by needling or like operations to cause entanglement of fibres
    • D04H1/48—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 the fleeces or layers being consolidated by mechanical means, e.g. by rolling by needling or like operations to cause entanglement of fibres in combination with at least one other method of consolidation
    • D04H1/482—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 the fleeces or layers being consolidated by mechanical means, e.g. by rolling by needling or like operations to cause entanglement of fibres in combination with at least one other method of consolidation in combination with shrinkage
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/14—Other self-supporting filtering material ; Other filtering material
    • B01D39/16—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres
    • B01D39/1607—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being fibrous
    • B01D39/1623—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being fibrous of synthetic origin
    • 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
    • D04H1/42—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 characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
    • D04H1/4326—Condensation or reaction polymers
    • 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
    • D04H1/42—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 characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
    • D04H1/4326—Condensation or reaction polymers
    • D04H1/4334—Polyamides

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Textile Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Filtering Materials (AREA)
  • Nonwoven Fabrics (AREA)

Abstract

A filter means comprises a non-woven fibre mass in which at least a proportion of the fibres have been shrunk. In a process for the manufacture of the filter means, the structure of a fibre mass which has been physically consolidated by e.g. needling and which contains from 30 to 100% of shrinkable fibres is fixed by subsequent fibre shrinkage. Polyvinyl chloride, polyvinylidene chloride, polyamide and polyester fibres are specified. The filter means may be used for filtering liquids, especially viscous media. The filter means has good particle retention and throughput, while only little work is required for filter cleaning.

Description

SPECIFICATION Improvements in and relating to filters The invention relates to a filter means suitable for filtering liquids, especially viscous media such as cellulose solutions, and to the manufacture of such filter means.
The most commonly used filter means for viscose and other cellulose solutions were for many years filter cloths of natural and synthetic fibres which were partially roughened in order to improve the filtering action.
These filter means, which are still used today, can be adapted to the required degree of particle retention by the choice of a suitable fabric density. However, the high filtrate purity which can be obtained is associated with a low filtration efficiency which falls rapidly as the duration of filtration increases, so that after a short time intensive cleaning of the filter is required. It is not possible to carry out this cleaning operation on the filter press by means of back-washing with the filtration medium or with a solvent, and the filter cloths must therefore be removed from the filter press and washed in washing machines. This operation involves heavy physical labour and, generally, also exposure to noxious substances.
Recently, nonwoven media of synthetic fibres have been used in place of filter cloths. This results in a considerable increase in efficiency in terms of throughput per unit area of the filter, while particle retention remains relatively good.
For filtering viscose, polyamide nonwoven media are preferably used, but polyvinyl chloride (DD-PS 51 624), polypropylene and polyester nonwoven media may also be employed, or two or more fibre types may be mixed.
As a result of the depth effect of nonwoven media, these nonwoven media, with a suitably fine fibre titre, have good particle retention and better filtration efficiency than comparable filter cloths; however, they cannot be adequately cleaned by backwashing.
Except in the case of floating filtration using plastics powder as the filter medium, automatic filter cleaning in viscose filtration was achieved only with the use of very fine woven metallic cloths. These woven metallic cloths are backwashed continuously with the filtration medium and thus achieve, over a prolonged period, a filtration efficiency which remains constant within certain limits, particle retention still being at an acceptable level (US-PS 3 393 262).
Replacing the woven wire cloths with sintered metallic nonwoven media led to an improvement in particle retention due to the depth effect of the filters, while the nonwoven media could be cleaned very successfully by backwashing with the filtration medium (Viscomatic or Brunswick filters, DE-OS 2 715 289). These filters operate fully automatically and require a change of filter medium only at relatively long intervals when this becomes worn. The costs of manufacturing the filter medium are, however, very high.
The invention is concerned with a filter means which advantageously comprises synthetic fibre material and can be backwashed, whose manufacture is relatively simple and which is easy to clean because it may be cleaned on the filtering apparatus.
The present invention provides a process for the manufacture of a filter means which comprises causing shrinkage of fibres in a physically consolidated fibre mass containing from 30 to 100% of shrinkable fibres, and filter means manufactured by the process. Consolidation ofthe fibre mass may be effected by any suitable method, for example, any method known for consolidating fibre masses.
The invention also provides a process for the manufacture of a filter means of non-metallic fibre material for filtering liquids, especially viscous media, wherein a fibre mass which has been physically consolidated by known methods and contains from 30 to 100% of shrinkable fibres is fixed in its inner structure by subsequent fibre shrinkage, and filter means manufactured by the process.
The invention also provides a filter means comprising a non-woven fibre mass in which at least a proportion of the fibres have been shrunk, and further provides a filter means comprising a physically consolidated non-woven fibre mass in which at least a proportion of the fibres have been shrunk.
The invention also provides a filtration process wherein a filter means according to the invention, including a filter means made by the process of the invention, is used, and further provides such a filtration process wherein the filter means is backwashed while in the filtering apparatus.The invention also provides filtering apparatus comprising a filter means according to the invention, including a filter means made by the process of the invention.
The invention thus provides a filter means for filtering liquids, especially viscous media, for example, cellulose solutions, and a process for making such a filter means. The filter means has very good particle retention and a good average throughput, it being possible to clean the filter means by backwashing.
Fibre shrinkage can be carried out, for example, by means of sintering, in which case the sintering temperature must be matched to the softening point of the shrinkable fibres used: sintering is carried out at or near the softening point. Moreover, fibre shrinkage can be carried out with the application of a compressive load.
The fibre mass can be manufactured, for example, by needle-punched felt technology. It has proved especially advantageous if this fibre mass is composed of several layers that differ in thickness, density and fibre fineness.
The use of shrinkable fibres in the fibre mass (for example polyvinyl chloride or polyvinylidene chloride/polyvinylchloride fibres) is of particular importance for the subsequent fibre shrinkage according to the invention. For instance, arranging the fibres together rigidly, which may be effected, for example, by means of a sintering operation, largely prevents the filter means being compressed by the filtering pressure and thus prevents a change in the pore structure during the filtering operation. Relatively high throughputs are thus obtained, and for the same reason very good discharge of the filtered particles from the filter means is possible on backwashing.
It is therefore one of the particular advantages of the invention that higherthroughputs are obtained with the filter means manufactured by the process according to the invention than with previously proposed non-metallic filter means, so that finer fibres-can be used forthe manufacture in order to achieve better particle retention.
The mostimportantfeature of this filter means is that it can be cleaned by backwashing iwth thefiltration medium or with a suitable solvent, for example sodium hydroxide solution, as a result of which its use proves advantageous even in continuous production processes, such as viscose filtration.
Example A fibre mass of 70% PVC staple fibre (titre 0.36 tex, length of staple 60 mm) with the- addition of 30% polyamide staple fibre (titre 0.36 tex, length of staple 85mm) is consolidated by needle-punched felt technology with a polyamide supporting insert and needle-punching with 220 punches/cm2. The weight per unit area of the nonwoven medium is 950 g/m2 and the layer thickness is approximately 5 mm.
Fixing of its inner structure (that is, the structure of the fibre means) is carried out by sintering for 45 minutes at 140or under a compressive-load application of 25 p/cm2 (25 pond/cm2). A filter means is obtained which has the following properties: Particle retention in the range of 8 - 10,ubm 70 - 80% 12 - 20pm 80-90% > 20 Fm ~90% The average throughput of the nonwoven medium is 1-2Vm2/h (1 -2 tonne/m2/hour) and after each backwashing operation approximately 70-90% of the initial capacity is achieved again.

Claims (23)

1. A process for the manufacture of a filter means which comprises causing shrinkage of fibres in a physically consolidated fibre mass containing from 30 to 100% of shrinkable fibres.
2. A process as claimed in claim 1, wherein fibre shrinkage is effected by heating.
3. A process as claimed in claim 1, wherein fibre shrinkage is effected by means of a sintering operation.
4. A process as claimed in any one of claims 1 to 3, wherein a compressive load is applied during fibre shrinkage.
5. A process as claimed in any one of claims 1 to 4, wherein the fibres are non-metallic fibres.
6. A process as claimed in any one of claims 1 to 5, wherein the fibre mass comprises polyvinyl chloride fibres.
7. A process as claimed in any one of claims 1 to 6, wherein the fibre mass comprises polyvinylidene chloride fibres.
8. A process as claimed in any one of claims 1 to 7, wherein the fibre mass comprises polyamide fibres.
9. A process as claimed in any one of claims 1 to 8, wherein the fibre mass is consolidated by needle-punched felttechnology.
10. A process as claimed in any one of claims 1 to 9, wherein the fibre mass comprises a plurality of layers.
11. A process as claimed in claim 10, wherein at leasttwo of the layers differ from each other in thickness, density andlor fibre thickness.
12. A process for the manufacture of a filter means of non-metallic fibre material for filtering liquids, especially viscous media, wherein the structure of a fibre mass that has been physically consolidated and which contains from 30 to 100% of shrinkable fibres is fixed by subsequentfibre shrinkage.
13. A process for the manufacture of a filter means carried out substantially as described in the Example herein.
14. Filter means whenever manufactured by a process as claimed in any one of claims 1 to 13.
15. A filter means comprising a non-woven fibre mass in which at least a proportion of the fibres have been shrunk.
16. A filter means comprising a physically consolidated non-woven fibre mass in which at least a proportion ofthefibres have been shrunk.
17. Afilter means as claimed in claim 15 or in claim 16, wherein shrinkage has been effected in a manner specified in any one of claims 2 to 4.
18. A filter means as claimed in any one of claims 15 to 17, wherein the fibre mass is-as specified in any one of claims 5 to 11.
19. A filter means as claimed in claim 15 or claim 16, constructed substantially as described herein.
20. A filtration process wherein a filter means as claimed in any one of claims 14 to 19 is used.
21. A filtration process as claimed in claim 20, wherein the filter means is backwashed while in the filtering apparatus.
22. Filtering apparatus comprising a filter means as claimed in any one of claims 14 to 19.
23. Any novel feature or any novel combination of features described herein.
GB08605411A 1985-03-07 1986-03-05 Improvements in and relating to filters Expired GB2172020B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DD27388985A DD235188A1 (en) 1985-03-07 1985-03-07 METHOD FOR PRODUCING A FILTER FROM NON-METAL FIBER MATERIAL

Publications (3)

Publication Number Publication Date
GB8605411D0 GB8605411D0 (en) 1986-04-09
GB2172020A true GB2172020A (en) 1986-09-10
GB2172020B GB2172020B (en) 1989-01-11

Family

ID=5565859

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08605411A Expired GB2172020B (en) 1985-03-07 1986-03-05 Improvements in and relating to filters

Country Status (5)

Country Link
DD (1) DD235188A1 (en)
DE (1) DE3543412A1 (en)
FR (1) FR2578443B1 (en)
GB (1) GB2172020B (en)
SE (1) SE8601048L (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2269603A (en) * 1992-08-14 1994-02-16 Du Pont Process for the production of fluff pulp
CN111135789A (en) * 2019-12-13 2020-05-12 上海勇意环境工程有限公司 360-degree flexible air purification material and preparation method thereof

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102008054584A1 (en) 2008-12-12 2010-06-17 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Filter medium for solid-free extraction of process water from digester outputs that are emerged through biological dismantling of renewable raw materials and biogenic raw materials, comprises a structure that is formed from coarse material

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1127364A (en) * 1965-10-01 1968-09-18 Edward W Andrew Ltd Improvements in or relating to filtering media
GB1141363A (en) * 1965-02-20 1969-01-29 Ici Fibres Ltd Non-woven fabrics and methods of making them
GB1206010A (en) * 1966-05-27 1970-09-23 Michisuke Kinoshita Felt for paper-making and the like
GB1226150A (en) * 1967-11-09 1971-03-24
GB1230577A (en) * 1967-06-28 1971-05-05
GB1232949A (en) * 1967-04-25 1971-05-26
GB1297405A (en) * 1970-05-08 1972-11-22
GB1602878A (en) * 1978-04-28 1981-11-18 Webron Products Ltd Stitchbonded nonwoven filter fabric
GB2084625A (en) * 1980-09-24 1982-04-15 Webron Products Ltd Finishing a tubular felted sleeve

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE756132A (en) * 1969-09-17 1971-03-15 Kalle Ag METHOD FOR THE CONTINUOUS PREPARATION OF A DENSIFIED FIBERGLASS TAPE BY HOT SHRINKING AND DEVICE FOR IMPLEMENTING THE PROCESS
JPS5063276A (en) * 1973-10-06 1975-05-29
DE7432111U (en) * 1974-09-25 1976-04-15 Gebr. Roeders Ag, 3040 Soltau FILTER ELEMENT

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1141363A (en) * 1965-02-20 1969-01-29 Ici Fibres Ltd Non-woven fabrics and methods of making them
GB1127364A (en) * 1965-10-01 1968-09-18 Edward W Andrew Ltd Improvements in or relating to filtering media
GB1206010A (en) * 1966-05-27 1970-09-23 Michisuke Kinoshita Felt for paper-making and the like
GB1232949A (en) * 1967-04-25 1971-05-26
GB1230577A (en) * 1967-06-28 1971-05-05
GB1226150A (en) * 1967-11-09 1971-03-24
GB1297405A (en) * 1970-05-08 1972-11-22
GB1602878A (en) * 1978-04-28 1981-11-18 Webron Products Ltd Stitchbonded nonwoven filter fabric
GB2084625A (en) * 1980-09-24 1982-04-15 Webron Products Ltd Finishing a tubular felted sleeve

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2269603A (en) * 1992-08-14 1994-02-16 Du Pont Process for the production of fluff pulp
CN111135789A (en) * 2019-12-13 2020-05-12 上海勇意环境工程有限公司 360-degree flexible air purification material and preparation method thereof
CN111135789B (en) * 2019-12-13 2022-05-27 上海勇意环境工程有限公司 360-degree flexible air purification material and preparation method thereof

Also Published As

Publication number Publication date
GB8605411D0 (en) 1986-04-09
SE8601048D0 (en) 1986-03-06
DD235188A1 (en) 1986-04-30
FR2578443B1 (en) 1989-08-04
FR2578443A1 (en) 1986-09-12
SE8601048L (en) 1986-09-08
GB2172020B (en) 1989-01-11
DE3543412A1 (en) 1986-09-11

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PCNP Patent ceased through non-payment of renewal fee