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
  • D04H1/542—Adhesive fibres
  • D04H1/544—Olefin series
• • 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
  • D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
  • D01F8/04—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers
  • D01F8/06—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers with at least one polyolefin as constituent
• • 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
  • D04H1/425—Cellulose series
• • 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
  • D04H1/425—Cellulose series
  • D04H1/4258—Regenerated cellulose series
• • 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
• • 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
  • D04H1/43825—Composite fibres
  • D04H1/43828—Composite fibres sheath-core
• • 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
  • D04H1/43835—Mixed fibres, e.g. at least two chemically different fibres or fibre blends
• • 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
  • 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
  • D04H1/541—Composite fibres, e.g. sheath-core, sea-island or side-by-side; Mixed fibres
  • D04H1/5412—Composite fibres, e.g. sheath-core, sea-island or side-by-side; Mixed fibres sheath-core
• • 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
  • D04H1/541—Composite fibres, e.g. sheath-core, sea-island or side-by-side; Mixed fibres
  • D04H1/5414—Composite fibres, e.g. sheath-core, sea-island or side-by-side; Mixed fibres side-by-side
• • 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
  • D04H1/70—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres
  • D04H1/72—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged
  • D04H1/732—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged by fluid current, e.g. air-lay

Definitions

• the present invention relates to drylaid nonwoven materials comprising polyolefin bicomponent fibres having excellent bonding affinity for natural fibres such as cellulose fibres.
• Hygienic absorbent products such as disposable diapers contain, in addition to a water-permeable coverstock, a water-impermeable backsheet and one or more layers for distribution of liquid, an absorbent core typically comprising natural fibres such as cellulose fluff pulp fibres, synthetic fibres based on e.g. polyolefin and/or polyester and a superabsorbent polymer (SAP) material.
• an absorbent core typically comprising natural fibres such as cellulose fluff pulp fibres, synthetic fibres based on e.g. polyolefin and/or polyester and a superabsorbent polymer (SAP) material.
• SAP superabsorbent polymer
• the synthetic fibres which often are bicomponent fibres of e.g. polypropylene/polyethylene or polyester/polyethylene, are thermobonded to each other to form a supporting network for the core.
• the synthetic fibres should be able to not only bond to each other, but also to the natural fibres and the SAP, so as to result in a core structure which is as strong and coherent as possible, and in which the natural fibres and the SAP are locked into place within the structure.
• the existing synthetic fibres that are used for the production of drylaid, e.g. airlaid, nonwovens suffer from the disadvantage of suboptimal bonding to e.g. cellulose fibres.
• the problem is made worse by the fact that the natural fibres are typically relatively short, e.g. fluff pulp fibres with a length of not more than about 3 mm, as compared to the synthetic fibres, which are normally (although not necessarily) considerably longer.
• dust problems are created in the manufacturing process, and the performance of the resulting nonwovens is also suboptimal, since a large proportion of the natural fibres is not bonded to any of the synthetic fibres or otherwise held in place by means of the structure formed by bonding of the synthetic fibres.
• EP 0465203-B1 discloses thermally bonded fibrous wet laid webs containing bicomponent fibres comprising a first component of polyester, polyamide or polypropylene and a second component of linear low density polyethylene (LLDPE) with a density of 0.88-0.945 g/cc and a grafted high density polyethylene (HDPE) with a density of 0.94-0.965 g/cc which has been grafted with maleic acid or maleic anhydride to provide succinic acid or succinic anhydride groups along the HDPE polymer.
• LLDPE linear low density polyethylene
• HDPE grafted high density polyethylene
• EP 0421734-B1 discloses thermobondable bicomponent fibres composed of two different polyolefins having melting points which differ by at least 20°C, the lower melting polyolefin containing 3-10% by weight of a monoglyceride of a fatty acid of 12 or more carbon atoms incorporated therein.
• the fibres are reported to be easily processable without the need for an oiling agent to be applied during spinning or drawing.
• US 4,950,541 discloses succinic acid and succinic anhydride grafts of linear ethylene polymers obtained by grafting maleic acid or maleic anhydride onto a LDPE (low density polyethylene), LLDPE or HDPE polymer.
• the grafted polymers are dyeable and can be used e.g. as the sheath component of a bicomponent fibre.
• EP 0465203-A discloses wetlaid bonded fibrous webs comprising bicomponent fibres including a first component of polyester or polyamide and a second component of linear low density polyethylene.
• the second component may also include a grafted high density polyethylene.
• US 4/684,576 discloses the production of blends of grafted HDPE with ungrafted LLDPE or LDPE, the HDPE having been grafted with maleic acid or maleic anhydride to provide succinic acid or succinic anhydride groups along the HDPE polymer.
• the blends are disclosed for use in producing laminate structures.
• polyolefin bicomponent fibres whose low melting component comprises a non-grafted polyolefin component and a grafted polyolefin component which has been grafted with an unsaturated dicarboxylic acid or an anhydride thereof have advantageous properties when used in the production of drylaid nonwoven materials, including improved bonding to cellulose pulp fibres and improved strength properties in the resulting nonwovens.
• the present invention relates to a drylaid nonwoven material comprising bicomponent fibres and at least one additional fibrous material, the bicomponent fibres comprising a low melting polyolefin component and a high melting polyolefin component, wherein the low melting polyolefin component has a melting point at least 4°C lower than the melting point of the high melting polyolefin component, the low melting polyolefin component constituting at least a part of the surface of the fibre and comprising a non-grafted polyolefin component and a grafted polyolefin component, wherein the grafted polyolefin component has been grafted with an unsaturated dicarboxylic acid or an anhydride thereof.
• Another aspect of the invention relates to a method for producing a drylaid nonwoven material, comprising forming a fibrous web using dry lay nonwoven equipment, the web comprising bicomponent fibres and at least one additional fibrous material, the bicomponent fibres comprising a low melting polyolefin component and a high melting polyolefin component, wherein the low melting polyolefin component has a melting point at least 4°C lower than the melting point of the high melting polyolefin component, the low melting polyolefin component constituting at least a part of the surface of the fibre and comprising a non-grafted polyolefin component and a grafted polyolefin component, wherein the grafted polyolefin component has been grafted with an unsaturated dicarboxylic acid or an anhydride thereof, and bonding the fibrous web to result in the drylaid nonwoven material.
• a further aspect of the invention relates to a bicomponent fibre as described above for the production of drylaid nonwoven materials.
• polyolefin component for the purpose of this invention means a polyolefin-containing polymeric material of which the largest part (by weight) consists of homo- or copolymers of monoolefins such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, etc.
• examples of such polymers are isotactic or syndiotactic polypropylene, polyethylenes of different densities, such as high density polyethylene, low density polyethylene and linear low density polyethylene and blends of the same.
• the polymeric material may be mixed with other non-polyolefin polymers such as polyamide or polyester, provided that polyolefins still constitute the largest part of the composition.
• the melts used to produce the polyolefin-containing fibres may also contain various conventional fibre additives, such as calcium stearate, antioxidants, process stabilizers, compatibilizers and pigments, including whiteners and colourants such as TiO 2 , etc.
• various conventional fibre additives such as calcium stearate, antioxidants, process stabilizers, compatibilizers and pigments, including whiteners and colourants such as TiO 2 , etc.
• dirylaid nonwoven refers to a nonwoven material produced by a dry process, including airlaid nonwovens, carded nonwovens, etc.
• the bicomponent fibres may be of the sheath-core type with the core being located either eccentrically (off-center) or concentrically (substantially in the center), or of the side-by-side type, in which each of the two components typically has a semi-circle cross section.
• Bicomponent fibres having irregular fibre profiles are also contemplated, e.g. an oval, ellipse, delta, star, multilobal, or other irregular cross section, as well as splittable fibres.
• the bicomponent fibres will typically have a high melting and low melting polyolefin component which comprise, respectively, polypropylene/polyethylene (the polyethylene comprising HDPE, LDPE and/or LLDPE), high density polyethylene/linear low density polyethylene, polypropylene random copolymer/polyethylene, or polypropylene/polypropylene random copolymer.
• a high melting and low melting polyolefin component which comprise, respectively, polypropylene/polyethylene (the polyethylene comprising HDPE, LDPE and/or LLDPE), high density polyethylene/linear low density polyethylene, polypropylene random copolymer/polyethylene, or polypropylene/polypropylene random copolymer.
• the difference in melting points the difference in melting points between the two polyolefin components may be quite small, e.g. about 7-8°C and in some cases even as low as about 4-5°C.
• the two components have melting points which differ by at least about 20°C, preferably at least about 25°C, more preferably at least about 28°C, e.g. at least about 30°C.
• a presently preferred aspect of the invention relates to a drylaid nonwoven material containing polyolefin bicomponent fibres in which the low melting polyolefin component comprises a non-grafted component and a grafted component, the grafted component having been grafted with an unsaturated dicarboxylic acid or an anhydride thereof.
• acids and anhydrides are maleic acid, maleic anhydride and derivatives thereof such as citraconic acid, citraconic anhydride and pyrocinchonic anhydride; fumaric acid and derivatives thereof; unsaturated derivatives of malonic acid such as 3-butene-1,1-dicarboxylic acid, benzylidene malonic acid and isopropylidene malonic acid; and unsaturated derivatives of succinic acid such as itaconic acid and itaconic anhydride.
• maleic acid, maleic anhydride and derivatives thereof such as citraconic acid, citraconic anhydride and pyrocinchonic anhydride
• fumaric acid and derivatives thereof unsaturated derivatives of malonic acid such as 3-butene-1,1-dicarboxylic acid, benzylidene malonic acid and isopropylidene malonic acid
• unsaturated derivatives of succinic acid such as itaconic acid and itaconic anhydride.
• Maleic acid and maleic anhydride are particularly preferred as the dicarboxylic acid or anhydride thereof.
• the resulting chain is provided with succinic acid or succinic anhydride groups, respectively, grafted onto it.
• the grafting of the dicarboxylic acid or anhydride thereof onto the polyolefin may be performed in a manner that is known per se, see e.g. the above-mentioned EP 0465203, US 4,950,541 and US 4,684,576.
• the weight ratio of grafted polyolefin to non-grafted polyolefin in the low melting polyolefin component of the bicomponent fibres will be within the range of about 1:99 to 50:50, typically about 1.5:98.5 to 30:70, more typically about 2:98 to 20:80, e.g. about 3:97 to 15:85, such as about 5:95 to 10:90.
• the content of carboxylic acid or anhydride thereof is typically in the range of about 1-30 (by weight), typically about 2-20%, more typically about 3-15%, such as about 5-10%.
• the weight ratio between the high melting and low melting polyolefin components will be in the range of from 10:90 to 90:10, typically about 20:80 to 80:20, more typically about 30:70 to 70:30, e.g. 35:65 to 65:35.
• drylaid nonwovens according to the invention comprising polyolefin bicomponent fibres and natural fibres may be characterised by an improved bonding of the bicomponent fibres to the natural fibres as determined by a standardised dust test whose result reflects the quality of the bonding between the two types of fibres.
• drylaid nonwoven samples having a base weight of about 85 g/m 2 and a thickness of about 1.1 mm are prepared using a line speed of 20 or 40 m/min from a mixture of 25% by weight of the synthetic fibres being tested and 75% by weight of a cellulose pulp fibre (e.g. NB 416 from Weyerhauser).
• Nonwovens to be tested are generally prepared using a series of different bonding temperatures (e.g. using hot air or calender bonding, typically a hot air oven) in order to optimise the properties of a given nonwoven.
• Test Method A Before the measurement is carried out, the nonwoven samples to be tested are conditioned for at least 12 hours to ensure that all of the samples have been subjected to the same temperature and humidity conditions. Since, as described below, the results are often expressed as a relative value compared to a control, the exact temperature and relative humidity for the conditioning of the samples is not critical, as long as all samples to be compared have been subjected to the same conditions. Ambient temperature and humidity conditions may therefore be used. Prior to conditioning, the nonwovens are cut into individual samples with a size of 12 x 30 cm.
• a cardboard strip with a width of 5 mm is attached to the short sides of the sample, after which the sample with the attached cardboard strips is weighed on a laboratory scale with an accuracy of ⁇ 0.1 mg.
• the nonwoven sample to be tested is then fixed with two clamps having a length of 12 cm, each of which is mounted on an arm.
• the exposed area of the fixed nonwoven is about 310 cm 2 , which is about the size of a piece of A4 paper.
• One of the arms is stationary, while the other arm is rotatable and is attached to a spring.
• the test is performed by rotating the rotatable arm 45°, so that the nonwoven sample goes from a "stretched out” condition to a "relaxed” condition, after which the rotatable arm is released, whereby the action of the spring returns the rotatable arm to its original position.
• the movement of the arm is stopped by the nonwoven sample, which thus is subjected to a small vibration and stretching effect designed to be similar to the conditions a nonwoven roll is subjected to when it is unrolled at the converter, the vibration and stretching resulting in a loss of loose fibres at the fibre surface. This action is repeated 50 times.
• the stretching force the sample is subjected to must of course lie within the non-woven's elasticity limit, so that the nonwoven is not substantially deformed or damaged during the test.
• the force provided by the spring must obviously be compatible with the nonwoven to be tested, so that the nonwoven is on the one hand returned to its original stretched out position and subjected to a slight vibration and stretching, but is on the other hand not excessively stretched so as to become deformed or damaged.
• the sample After having been subjected to the vibration/stretching action 50 times, the sample is again weighed, and the difference between the two values is calculated and expressed as mg of dust.
• the result in mg will often be no more than about 15 mg, typically no more than about 10 mg, preferably no more than about 5 mg, more preferably no more than about 4 mg, still more preferably no more than about 3 mg, most preferably no more than about 2 mg.
• the result can be as low as about 1 mg of dust.
• An alternative and often preferred way of defining the dust-reducing properties of a given fibre in the standardised dust test is in terms of reduction of the amount of dust (in mg) in a standard nonwoven prepared from fibres of the invention compared to a similar nonwoven prepared from similar fibres without the grafted polyolefin component.
• the nonwoven prepared from the fibres of the invention should show a dust reduction of at least about 40% by weight compared to the control nonwoven prepared with the control fibres, typically at least about 50% by weight.
• the dust reduction is at least about 60%, more preferably at least about 70%, and still more preferably at least about 80%.
• the dust reduction can be as much as about 90% or more.
• the dust properties of a given nonwoven can vary greatly depending on factors such as the nature of the bicomponent fibres and the nature of the cellulose or other fibres as well as e.g. the particular webforming and bonding process, it will often be preferred to compare the performance of a given fibre in terms of its dust reduction percentage compared to a similar control fibre rather than in terms of an absolute value in mg.
• the fibres of the invention will also show an improved bonding and fixation of not only cellulosic fibres but also different superabsorbent polymers (SAP) that are commonly used in hygiene absorbent products in the form of particles or fibres.
• SAPs e.g. a crosslinked polyacrylic acid salt
• SAPs are typically used in the form of superabsorbent particles in the absorbent core of e.g. disposable diapers, since they are able to absorb many times their weight in liquid and form a gel that holds onto the liquid upon wetting.
• the improved bonding of the fibres of the invention to the cellulosic fibres will result in an improved structure that in itself serves to ensure that the SAP particles are maintained in the desired location in the absorbent product, whereby the function of the SAP will be improved.
• the spinning of the fibres is preferably accomplished using conventional melt spinning (also known as “long spinning"), with spinning and stretching being performed in two separate steps.
• melt spinning also known as “long spinning”
• other means of manufacturing staple fibres in particular "compact spinning", which is a one step operation, may be used to carry out the invention.
• Methods for the spinning of bicomponent fibres and filaments are well-known in the art. Such methods generally involve extrusion of the melts to produce filaments, cooling and drawing of the filaments, treatment of the filaments with an appropriate spin finish to result in desired surface properties, e.g.
• a spin finish to provide hydrophilic properties when the fibres are to be used in an absorbent core and/or to provide antistatic properties, stretching the filaments, typically, treating with a second spin finish, texturizing the filaments, drying the filaments and cutting the filaments to result in staple fibres.
• the drylaid nonwovens of the present invention typically comprise, in addition to the polyolefin bicomponent fibres, at least one additional fibrous material, in particular natural fibres or regenerated fibres, e.g. selected from cellulose fibres, viscose rayon fibres and Lyocell fibres.
• the cellulose fibres may e.g. be pulp fibres or cotton fibres and are in particular pulp fibres such as CTMP (chemi-thermo-mechanical pulp), sulfite pulp or kraft pulp.
• the fibrous web comprising the bicomponent fibres and the additional fibrous material will typically comprise 5-50% by weight of the bicomponent fibres and 50-95% by weight of the additional fibrous material, more typically 10-40% by weight of the bicomponent fibres and 60-90% by weight of the additional fibrous material, e.g. 15-25% by weight of the bicomponent fibres and 75-85% by weight of the additional fibrous material.
• the cellulose fibres were NB 416 from Weyerhauser.
• the weight ratio of between the bicomponent fibres and the cellulose fibres was 25:75.
• the tested bicomponent fibres had the following composition, fibre No. 1 being according to the present invention:
• Bicomponent fibres 1, 2 and 3 all had a fineness of 1.7 dtex, a length of 6 mm and a weight ratio between core and sheath of 35:65.
• the fibres were run at a very low speed of 8.33 m/min on an airlaid apparatus (Dan-Web, Denmark), since the primary purpose of these trials was to determine the fibres' ability to bond to cellulose.
• an airlaid nonwoven product having a basis weight of 80 g/m 2 was aimed at, and the trials were started at the lowest possible bonding temperature, after which the temperature in the oven was increased in increments of 5 or 10°C.
• the cross direction (CD) dry strength, machine direction (MD) dry strength and MD wet strength were determined on samples produced at different temperatures as indicated below (EDANA test method No. 20.2-89, tested at a speed of 100 mm/min). Furthermore, the thickness and the basis weight (g/m 2 ) of each sample was determined, and this information (not listed below) was used to adjust the strength values to result in normalised values that are comparable in spite of minor differences in thickness and base weight of the individual samples tested. The results are shown below. Sample No. Bonding Temp.
• fibre 1 according to the invention gave a significantly improved result in the dust test, the greatly reduced dust generation reflecting a significantly improved bonding of the bicomponent fibres of the invention to the cellulose fluff pulp fibres. Observation of the samples by microscope also revealed bonding of the bicomponent fibres of the invention to the cellulose fibres. It was also found that fibre 1 gave a bulkier nonwoven compared to fibres 2 and 3 (fibre 4 was not compared in this regard). Furthermore, as shown by the strength values given in the table above, the fibres of the invention resulted in nonwovens with improved strength and elongation characteristics.
• a test of the ability of two different fibres to bind cellulose was performed in a test on a commercial airlaid line. Airlaid nonwovens with a basis weight of about 80 g/m 2 and a thickness of about 1 mm were produced. The nonwovens contained 25% by weight of bicomponent fibres and 75% by weight of cellulose pulp fibres. The bicomponent fibres tested had a fineness of 1.7 dtex and a length of 6 mm. In addition to (control) fibre No. 3 described above, a bicomponent fibre (referred to as No. 5) with the same cellulose-binding additive as in fibre No. 1 but a higher melting polyethylene sheath component (HDPE) was tested. This fibre thus had the following composition:
• the individual nonwoven samples were bonded at different temperatures with intervals of 3°C in order to ascertain the optimum bonding temperature for the individual fibres.
• nonwovens containing bicomponent fibres of the invention resulted in an improved binding of the cellulose fibres as evidenced by a reduced generation of dust during processing compared to the control fibre(quantitative measurements were not performed in this case). Furthermore, the fibres of the invention resulted in nonwovens with improved strength characteristics as evidenced by the following test results: MD tensile strength, dry (N/5 cm) Bonding Temp. °C Fibre Control 5 137 13.96 15.08 140 15.77 19.01 143 12.56 19.40 146 - 15.41
• Tests were performed to illustrate the influence of varying the amount of additive (maleic acid grafted LLDPE with an active content of 5%) in the sheath component.
• the bicomponent fibres tested all had a fineness of 1.7 dtex and a length of 6 mm.
• the core/sheath weight ratio for fibres 6-9 was 35:65, and 50:50 for fibre No. 10.
• the core was in all cases of polypropylene.
• Nonwovens were produced on a commercial airlaid line using technology from Dan-Web, Denmark, the nonwovens having a basis weight of about 80 g/m 2 , a thickness of about 1 mm, and weight ratio of bicomponent fibres to cellulose fibres of 25:75. Samples with each of the bicomponent fibres were tested at 3 different bonding temperatures, 137, 140 and 143°C.
• the sheath composition of the individual fibres was as follows:
• the nonwovens containing the fibres of the invention showed a substantially improved dry and wet tensile strength compared to the control nonwovens.
• some of the fibres of the invention notably Nos. 6, 7 and 8, showed elongation values above those of the control fibres, while fibre 10 and to a certain extent fibre 9 showed elongation values lower than for the control fibres.
• the suboptimal results for fibres 9 and 10 in terms of elongation are believed to be related to the fact that some difficulties were experienced in spinning these fibres with a relatively large amount of the grafted component in the sheath.

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Nonwoven Fabrics (AREA)
• Multicomponent Fibers (AREA)
• Paper (AREA)
• Artificial Filaments (AREA)
• Woven Fabrics (AREA)

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• 1997
  • 1997-04-12 TW TW086104731A patent/TW436535B/zh not_active IP Right Cessation
• 1998
  • 1998-03-31 ID IDW991331A patent/ID24606A/id unknown
  • 1998-03-31 AU AU69182/98A patent/AU6918298A/en not_active Abandoned
  • 1998-03-31 EP EP98914837A patent/EP0973966B1/en not_active Expired - Lifetime
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  • 1998-03-31 WO PCT/DK1998/000131 patent/WO1998045519A1/en active IP Right Grant
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  • 1998-03-31 JP JP54226698A patent/JP3672324B2/ja not_active Expired - Lifetime
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