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
  • D04H1/492—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 by fluid jet
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M10/00—Physical treatment of fibres, threads, yarns, fabrics, or fibrous goods made from such materials, e.g. ultrasonic, corona discharge, irradiation, electric currents, or magnetic fields; Physical treatment combined with treatment with chemical compounds or elements
  • D06M10/02—Physical treatment of fibres, threads, yarns, fabrics, or fibrous goods made from such materials, e.g. ultrasonic, corona discharge, irradiation, electric currents, or magnetic fields; Physical treatment combined with treatment with chemical compounds or elements ultrasonic or sonic; Corona discharge
  • D06M10/025—Corona discharge or low temperature plasma
• • 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
  • D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
  • D21H13/10—Organic non-cellulose fibres
  • D21H13/12—Organic non-cellulose fibres from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H13/14—Polyalkenes, e.g. polystyrene polyethylene
• • 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
  • D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
  • D21H13/10—Organic non-cellulose fibres
  • D21H13/20—Organic non-cellulose fibres from macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H13/24—Polyesters
• • 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
  • D21H25/00—After-treatment of paper not provided for in groups D21H17/00 - D21H23/00
  • D21H25/04—Physical treatment, e.g. heating, irradiating

Definitions

• the present invention relates to a method for producing a hydro-entangled nonwoven material with increased wet strength.
• Hydro-entanglement or spunlacing is a method which was introduced in the 1970s, see for example Canadian patent no.841,938.
• the method involves forming either a dry-laid or wet-laid fibre web, whereafter the fibres are entangled by means of very fine water jets under high pressure. A plurality of rows of water jets are directed towards the fibre web which is carried on a displaceable wire. The entangled web is thereafter dried.
• Those fibres which are used in the material can be synthetic or regenerated staple fibres, e.g. polyester, polyamide, polypropylene, rayon and the like, pulp fibres or a mixture of pulp fibres and staple fibres.
• Spunlace materials can be produced to a high quality at reasonable cost and display high absorption capability. They are used inter alia as wiping materials for household or industrial applications, as disposable materials within health care, etc.
• Spunlace material based on mixtures of pulp fibres and relatively short ( ⁇ 25mm) synthetic or vegetable fibres often have good strength properties in a dry condition.
• the binding system in this type of material is, in a dry condition, a combination of friction between all the fibres in the material and of hydrogen bonds between the pulp fibres in the material. In water and other polar solvents, the hydrogen bonds between the pulp fibres more or less disappear and the strength of the material becomes very dependent on the friction between the fibres in a wet condition.
• This sensitivity to polar solvents can be reduced by the addition of various binders such as latex of conventional type based, for example, on ethylvinyl acetate, acrylates or styrene butadine.
• binders such as latex of conventional type based, for example, on ethylvinyl acetate, acrylates or styrene butadine.
• Wet strength resins of, for example, polyamide epichlorohydrine type also improve the strength properties of spunlace material.
• thermobonding Another method of raising the wet strength in spunlace material is by thermal bonding, which can be used where the material contains thermoplastic fibres.
• the thermoplastic fibres in the material are melted after the hydro-entanglement by means of raised temperature and pressure.
• the drawback with this method is that the material becomes stiffer and the fused thermoplastic fibres can locally form hard regions which can score delicate surfaces during, for example, polishing.
• a further drawback with thermal bonding is that fibre-recycling becomes more difficult with mixed material (e.g. cellulose/ polypropylene).
• Plasma is a general term for gases which comprise ions, electrons, free radicals, photons within the UV-range, molecules and atoms. Plasma is electrically neutral and is normally generated by electric discharge in which the energy source is in the form of radio or microwaves.
• Plasma treatment can be said to be a further development of corona treatment and the primary difference is that corona treatment takes place at atmospheric pressure whilst socalled glow discharge in cold plasma takes place at reduced pressure. Plasma treatment can be executed in the presence of different gases depending on which result is desired.
• Plasma treatment is used nowadays, for example, to provide plastic components with a coatable surface. It is also used to chemically modify the surface on fibres with an aim to increase the wettability of fibres, as well as to increase the adherence between fibres and a filler.
• Plasma treatment of reinforcement fibres which are to be embedded in a thermoplastic matrix is described in US-A-5,108,780. It is believed that the effect of the plasma treatment is that free radicals are formed on the fibre or material surface. These free radicals can then react with each other, with components in the plasma phase or with molecules in the atmosphere, for example oxygen gas, as soon as the treated material is removed from the plasma reactor.
• Corona treatment has long since been used to morphologically and chemically modify the surface of polymer films and in particular for the purpose of improving the adhesion of printing ink or to perforate the film.
• Apparatus for corona treatment is described in, for example, US-A-4,283,291. It is also known from, for example, US-A-4,535,020 and EP-A-0,483,859 to treat surface material for absorbent products such as diapers and sanitary napkins with corona at the same that the material is also treated with a surfactant to increase the liquid permeability. Thanks to the corona treatment, an improved permanent wettability is attained.
• wiping cloths of, for example, meltblown material can be treated with corona to provide the material with improved permanent absorption properties during repeated use.
• the object of the present invention is to provide a spunlace material which displays improved strength properties particularly in a wet condition by means of an after-treatment of the material without the addition of binders or thermal bonding.
• This is achieved according to the invention by subjecting the dried material to plasma or corona treatment after the hydro-entanglement.
• the plasma or corona treatment is believed to modify the surface of the fibres in such a manner that the fibre-to-fibre friction increases, something which would explain the improved strength properties of the treated material.
• Plasma treatment has been shown to be a very effective method of modifying the parameter which is desired to be changed in the described type of nonwoven material, i.e. the fibre-to-fibre friction in a wet condition.
• Surface modification by corona discharge at atmospheric pressure has also been shown to provide significant increases in the wet strength of the spunlace materials in question.
• the fibres making up the material can be synthetic or regenerated staple fibres, e.g. polyester, polyamide, polypropylene, rayon or the like, vegetable fibres, pulp fibres or mixtures thereof.
• the pulp fibres can be of chemical, mechanical, thermomechanical, chemical-mechanical or chemical-thermomechanical pulp (CTMP).
• CTMP chemical-thermomechanical pulp
• Addition of mechanical, thermomechanical, chemical-mechanical or chemical-thermomechanical pulp fibres provides a material with higher bulk and improved absorption and softness, which is described in our Swedish application no.9500585-6.
• the strength properties are, however, worsened which is why an after-treatment to increase the strength of the material can be necessary for certain applications. Plasma or corona treatment can thus be a suitable alternative.
• Examples of vegetable fibres which can be used are leaf fibres such as abaca, pinapple and phormium tenax, bast fibres such as flax, hemp and ramie and seed hair fibres such as cotton, kapok and milkweed.
• a dispersion agent for example a mixture of 75% bis(hydro-generated tallowalkyl)dimethyl ammonium chloride and 25% propylene glycol. This is described in greater detail in Swedish application nr. 9403618-3.
• a certain proportion of recycled fibres from textile waste, nonwoven waste and the like may also be included in the material. This is described in Swedish application nr. 9402804-0 EP-A-0777782. Since such material has lower strength compared to materials based on virgin fibre raw material, plasma or corona treatment can be a suitable method of improving the strength properties of these materials.
• dry fibres are airlaid on a wire, whereafter the fibre web is subjected to hydro-entanglement.
• the fibres are dispersed in liquid or in a foamed liquid containing a foam-forming surfactant and water.
• a foam-forming surfactant and water One example of a suitable such foam forming method is described in Swedish application nr. 9402470-0 EP-A-0776396.
• the fibre dispersion is drained on a wire and hydro-entangled with an energy input which may suitably lie in the range 200-800 kWh/ton.
• the hydro-entanglement takes place using conventional methods and equipment which is provided by machine manufacturers. Production of dry- and wet-formed spunlace material is described in, for example, CA 841,938.
• the hydro-entanglement of a wet- or foam-formed fibre web can either take place in-line, i.e. immediately after the fibre web has been drained on the wire, or on a wet-formed sheet which has been dried and wound up after the forming.
• a plurality of such sheets can be laminated together by hydro-entanglement.
• the material is pressed and dried then wound up.
• the thus produced material is thereafter converted in a known manner to a suitable format and packaged.
• the invention is of particularly great significance for wet- and foam-formed spunlace material where the choice of fibre length is more restricted since too long fibres are difficult to disperse in liquid or foam.
• the problem with sufficient wet strength is normally greater in a material which contains short fibres.
• the plasma or corona treatment of the material suitably takes place on the dry material before it is wound up.
• dry material is meant a material which has a moisture content of maximum 10% by weight calculated on the total weight of the material.
• gases which can be used during plasma treatment at reduced pressure are oxygen, nitrogen, argon, helium, ammonia, carbon tetrafluoride, carbon dioxide and organic unsaturated gases. Oxygen or nitrogen are hereby preferred.
• the material which is to be treated is fed through a plasma plant of commercially available type, e.g. from Centexbel.
• the treatment preferably takes place continuously, i.e. the material is fed continually through a vacuum chamber which contains electrodes, injection and evacuation means for the used gas, feeding means for the material and a high frequency generator.
• Corona treatment can take place using commercially available equipment, e.g. Ahlbrandt System ASOH12.
• the fibres of the materials were a mixture of chemical pulp fibres and synthetic fibres.
• the chemical pulp fibres were bleached chemical softwood pulp.
• the synthetic fibres which were used were polyester 1,35 denier (1,5 dtex) x 12,7 mm, respectively polypropylene 1,53 denier (1,7 dtex) x 12 mm and 1,53 denier (1,7 dtex) x 18 mm.
• the hydro-entanglement took place with an energy input of about 600 kWh/ton. After the hydro-entanglement and before the plasma or corona treatment, the materials were lightly pressed and dried by through-air drying at 130°C. The properties of the materials are listed in Tables 1 and 2 below.
• the material is eminently suitable as wiping material for household use or for commercial use in workshops, industry, hospitals and other public sectors. It may also be used as disposable material within health care, e.g. surgical gowns, bed sheets and the like. It may also be used as a component in absorbent products such as sanitary napkins, panty liners, diapers, incontinence products, bedding, wound dressings, compresses.

Landscapes

• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Physics & Mathematics (AREA)
• Plasma & Fusion (AREA)
• Mechanical Engineering (AREA)
• Nonwoven Fabrics (AREA)
• Chemical Or Physical Treatment Of Fibers (AREA)
• Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)
• Paper (AREA)
• Treatment Of Fiber Materials (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=20397366

Family Applications (1)

Country Status (13)

Cited By (1)

Families Citing this family (18)

Family Cites Families (2)

• 1995
  • 1995-02-27 SE SE9500702A patent/SE514726C2/sv not_active IP Right Cessation
• 1996
  • 1996-02-15 CA CA002213809A patent/CA2213809A1/en not_active Abandoned
  • 1996-02-15 AU AU48935/96A patent/AU696440B2/en not_active Ceased
  • 1996-02-15 DE DE69615365T patent/DE69615365T2/de not_active Expired - Fee Related
  • 1996-02-15 ES ES96905094T patent/ES2164871T3/es not_active Expired - Lifetime
  • 1996-02-15 JP JP8526189A patent/JPH11501085A/ja active Pending
  • 1996-02-15 EP EP96905094A patent/EP0833977B1/en not_active Expired - Lifetime
  • 1996-02-15 WO PCT/SE1996/000199 patent/WO1996027044A1/en active IP Right Grant
  • 1996-02-15 AT AT96905094T patent/ATE205895T1/de not_active IP Right Cessation
  • 1996-02-21 ZA ZA961387A patent/ZA961387B/xx unknown
  • 1996-02-24 TW TW085102099A patent/TW293046B/zh active
  • 1996-02-26 CN CN96105513A patent/CN1137584A/zh active Pending
• 1997
  • 1997-08-22 NO NO19973872A patent/NO310886B1/no unknown

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