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
  • D04H1/54—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
  • D04H1/56—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 in association with fibre formation, e.g. immediately following extrusion of staple fibres
• • 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
  • D04H1/4382—Stretched reticular film fibres; Composite fibres; Mixed fibres; Ultrafine fibres; Fibres for artificial leather
  • D04H1/43838—Ultrafine fibres, e.g. microfibres
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
  • D01D5/00—Formation of filaments, threads, or the like
  • D01D5/11—Flash-spinning
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
  • D01F6/02—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D01F6/16—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polymers of unsaturated carboxylic acids or unsaturated organic esters, e.g. polyacrylic esters, polyvinyl acetate
• • 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
  • D04H1/4282—Addition polymers
  • D04H1/4291—Olefin series

Definitions

• the invention relates to a process for manufacturing of superabsorbent plexifibrils and of fibrous sheets made out of them.
• the superabsorbent polymer will be mixed with water in a weight ratio of 1:0.5 to 1:10 to form a gel.
• This gel will be heated under pressure to a temperature of 120 to 230 °C (spinning temperature) and the mass will be extruded by means of a gear pump under a pressure, which should correspond at least to the equilibrium water pressure at the spinning temperature, through a spinneret into an expansion space which will be kept under a substantially lower pressure, than the spinning gel.
• a gear pump under a pressure, which should correspond at least to the equilibrium water pressure at the spinning temperature, through a spinneret into an expansion space which will be kept under a substantially lower pressure, than the spinning gel.
• this invention relates to a process where the weight ratio of superabsorbent polymer and water will be kept between 1:0.5 and 1:2. Further, the spinning temperature of the polymer gel may be kept between 130 to 200 °C. In an other embodiment of this invention, the pressure in the expansion space following he spinneret will be atmospheric pressure.
• the present invention also includes a process of producing a nonwoven fabric by forming a fibrous sheet at a foraminous conveyer belt evacuated from the bottom.
• this invention relates to superabsorbent plexifibrils manufactured according to the described process.
• SAP Superabsorbent polymers
• SAP polyacrylic acid
• PAA polyacrylic acid
• polyacrylic acid will be used for polymers containing more than 50 % acrylic acid monomer and which are non soluble in water, but capable to substantially swell in water.
• SAP of the class of polyacrylic acid include crosslinked polyacrylic acid or copolymers, starch grafted polyacrylnitril hydrolysates, starch and acrylic acid grafted crosslinked polymers as well as hydrolysates of copolymers based on vinylacetate and acrylic esters. In such polymers and copolymers, about 60 to 90 % of all carboxyl groups are neutralised by alcalic metals.
• SAP will be manufactured as powder or fine granulate.
• Product properties will be defined by absorption capacity, absorption speed, water permeability, gel stability over the time.
• Objective of this invention is to transfer superabsorbent polymers in a ultrafine fibrillar form allowing to reach a favourable combination of both high absorption capacity of low crosslinked acrylic acid polymers and sufficiently high absorption speed, the latter due to a ultrafine resolution of the SAP in form of plexifibrils.
• aqueous SAP gels containing 50 to 1000 weight-% water based on SAP will be heated at temperatures of 120 to 230 °C (spinning temperature) and extruded through a heated spinneret (a metal plate with small orifices) by means of a metering gear pump at a pressure at least corresponding to the equilibrium water steam pressure at the spinning temperature into an expansion space where the pressure will be substantially below the water steam pressure at the spinning temperature.
• the aqueous gel where the solvent (water) is present under supercritical conditions and instantly evaporates (flashes) just after it left the spinneret holes and so has been released from the high pressure conditions, will be disintegrated in form of ultrafine network of plexifibrils.
• the water vapour evaporated during the flash spinning process can not pollute the environment and can be released. Subsequently it is possible to perform the flash spinning process in an open space which can be kept under atmospheric pressure.
• Ultrafine SAP plexifibrils manufactured according to this flash spinning process have a particular network structure with extremely large specific surface. This improves the water absorption properties. Due to their particular network structure, SAP plexifibrils with a typical (macro-) lengths of 400 to 1000 mm and a typical (micro-) thickness of less than 4 ⁇ m, can be easily anchored and fixed in the basic wood pulp structure of typical absorption sheets. They show no trend to migration outside of the absorption core, regardless how much of SAP plexifibrils will be added.
• the present invention also includes a process of for producing a nonwoven fabric out of SAP plexifibrils, in which case the flash spun SAP plexifibrils will be collected at a foraminous conveyer belt.
• Such nonwoven SAP fabric provides excellent properties as an ultimate water absorbent. It can be used as one constituent of multiplies high performance absorption sheets.
• a very important advantage of the flash spinning process out of aqueous polymer gels according to this invention is the fact, that no organic solvents, what so ever, will be used, but water, providing with SAP gels, which can be under suitable conditions flash spun into SAP plexifibrils.
• water provides with SAP gels, which can be under suitable conditions flash spun into SAP plexifibrils.
• To use water as solvent represents a substantial economical advantage, because the evaporated solvent - water - need not to be carefully regenerated. On top this process is free of any pollution danger and can not spoil the environment.
• a screw plasticiser heated at 60 °C have been mixed 1 part of a commercial superabsorbent polymer powder based on polyacrylic acid Favor® manufactured by the Stockhausen Company with 1.5 parts water to form a gel.
• the gel was transferred into an extruder with a screw diameter of 30 mm., heated at 220 °C and by means of a heated metering gear pump extruded through a spinneret equipped with 12 holes.
• the spinneret package has been heated at 220 °C and has been equipped with a screen filter located between the spinneret entrance and the spinneret plate.
• the overheated gel was allowed to form bubbles due to depressurising of the spinning mass below the equilibrium water pressure at 220 °C.
• the throughput has been kept at 12 g of the gel per minute.
• a gel of superabsorbent polymer based on polyacrylic acid containing 2.3 weight parts of water on 1 weight part of SAP has been used.
• This has been an intermediate product resulting directly from the polymerisation of acrylic acid in aqueous solution.
• This gel was filled in an 30 mm extruder, heated at 200 °C and forwarded by means of a metering gear pump to a primary air spinneret.
• a "melt blown" spinneret has been used. It consists of a V-shaped spinneret body with orifices flanked by two air slots (one at each side) connected with a air heater.
• the spinneret was heated at 200 °C and the pressurised air has been heated at the same temperature.
• the entrance of the spinneret body formed a "bottle-neck" so, that in the larger space following, the spinning mass has been depressurised and allowed to form bubbles.
• the spinneret has been equipped with 50 holes.
• the throughput of the spinning mass has been kept at 0.5 g per hole and minute.
• plexifibrils have been formed in same way, which has been described in Example 1.
• plexifibrils By means of two hot air streams flanking the V-shaped spinneret body, plexifibrils have been additionally dried and forwarded to a foraminous conveyer belt located in a distance of 500 mm below the spinneret.
• a uniform sheet of SAP plexifibrils has been formed as a "SAP nonwoven fabric".
• a SAP gel has been made containing 5 weight parts of water at 1 weight part of SAP.
• the mass has been heated at 230 °C and forwarded by means of metering gear pump to a melt blown spinneret described in Example 2.
• the spinneret as well as the air have been heated at 230 °C.
• the throughput of the spinning mass has been kept at 1 g per hole and minute.
• SAP plexifibrils have been formed in same way, as described in Example 1 and Example 2. Due to higher water content it was necessary to increase the air stream and volume just to receive dry SAP plexifibrils.

Landscapes

• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Nonwoven Fabrics (AREA)
• Artificial Filaments (AREA)
• Absorbent Articles And Supports Therefor (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=7926406

Family Applications (1)

Country Status (2)

Cited By (1)

Citations (3)

• 1999
  • 1999-10-21 DE DE19950728A patent/DE19950728A1/de not_active Withdrawn
• 2000
  • 2000-10-19 WO PCT/EP2000/010517 patent/WO2001028596A2/en active Application Filing

Patent Citations (3)

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