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
  • 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
  • D01D5/08—Melt spinning methods
• • 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
  • D01F6/04—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyolefins
  • D01F6/06—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyolefins from polypropylene
• • 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
  • D01F6/28—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from copolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D01F6/30—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from copolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds comprising olefins as the major constituent
• • 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
  • D01F6/44—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds as major constituent with other polymers or low-molecular-weight compounds
  • D01F6/46—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds as major constituent with other polymers or low-molecular-weight compounds of polyolefins
• • 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

Definitions

• the present invention relates to a spinning process for the preparation of thermoweldable polyolefin fibers, in particular polypropylene based fibers, suitable for the preparation of nonwoven fabrics.
• Said nonwoven fabrics are particularly suitable for uses requiring considerable softness and tear resistance, as is the case with coverstock for diapers and sanitary wear, which are made from low count fibers, generally ranging from 0.2 to 5 dtex, or with also membranes, made from fibers having a count between 3 and 10 dtex.
• coverstock for diapers and sanitary wear which are made from low count fibers, generally ranging from 0.2 to 5 dtex, or with also membranes, made from fibers having a count between 3 and 10 dtex.
• the fundamental requirement of polyolefin fibers for nonwoven fabrics is that they must bond to each other by means of the joint action of temperature and pressure on which the hot calendering processes are based. This characteristic, called “thermoweldability", is not always present in polyolefin fibers, or at least not in the same degree. In fact basically thermoweldability depends on the type of polyolefin being span, the additives it contains, the type of process and the spinning conditions used.
• thermoweldable fibers obtained from the above mentioned stabilized polyolefin compositions by conventional spinning processes in particular processes for the production of staple fibers.
• the good levels of thermoweldability shown in the examples are due to the selection of the stabilizers.
• fibers having a count ranging from 1.9 to 2.2 dtex are prepared by using a typical "long-spinning" apparatus (characterized, among other things, by high fiber-winding speed) equipped with a die having holes with 0.4 mm diameter.
• the present invention provides a process for the preparation of thermoweldable fibers having preferably a count ranging from 0.2 to 10 dtex, more preferably from 0.5 to 3 dtex, where the dies used have a real or equivalent output diameter of the holes greater than or equal to 0.5 mm, particularly ranging from 0.5 to 2 mm, with the proviso that for fibers having a count greater than or equal to 4 dtex, the ratio of the said output hole diameter to the count is greater than or equal to 0.06 mm/dtex, preferably greater than or equal to 0.08 mm/dtex, more preferably greater than or equal to 0.1 mm/dtex.
• output diameter of the holes is the diameter of the holes at the outside surface of the die, i.e., on the front face of the die from which the fibers exit. Inside the thickness of the die, the diameter of the holes can be different from the diameter of the holes at the output.
• the “equivalent output diameter of the holes” refers to instances where the hole is not round, in which case, for the purpose of the present invention, one considers the diameter of the ideal circle having an area equal to the area of the output hole, which corresponds to the above mentioned equivalent diameter.
• the process of the present invention can be carried out by using both long-spinning and short-spinning apparatuses for the production of staple fibers, and spun-bonding apparatuses.
• Long-spinning apparatuses normally comprise a first spinning segment where the fibers are extruded and air-cooled in a quenching column. Subsequently, these fibers go to the finishing steps during which they are drawn, crimped-bulked and cut. Generally, the above mentioned finishing steps are carried out intermittently with respect to the spinning, in a specific section where the fiber rovings are gathered into one single roving having a total count ranging from 100 and 200 kilotex. Said roving is then sent to drawing, crimping-bulking and cutting apparatuses which operate in sequence at a spinning speed ranging from 100 to 200 m/min. In other types of long-spinning apparatuses the above mentioned finishing steps are carried out in sequence with the spinning step.
• the fibers go directly from the gathering to the drawing rollers, where they are drawn at a somewhat contained ratio (not greater than 1.5). Subsequently, they are gathered in rovings with a count of about 5 kilotex, then subjected to crimping-bulking and cutting at a speed comparable with that of the spinning.
• the long-spinning apparatuses allow for a better control of the process parameters compared to the control one has with the short-spinning apparatus.
• the process conditions which are generally adopted when using the long-spinning apparatuses are the following:
• the draw ratio be from 1.1 to 4.0.
• thermoweldability of staple fibers improves as the fibers gathering speed decreases.
• the process of the present invention is particularly advantageous when the short-spinning apparatuses are used, said apparatuses being characterized, among other things, by low fiber-gathering speeds (less than 500 m/min).
• short-spinning apparatuses allow for a continuous operation, since the spinning speed is compatible with the drawing, crimping and cutting speeds, and due to their simplicity and reduced overall volume, these apparatuses are more economical than the long-spinning ones and suited for small scale productions.
• short-spinning apparatuses did not allow one to obtain staple fibers having good thermoweldability values (higher than 2.5 N, for example, according to the measuring method described in the examples).
• the process of the present invention therefore, assumes particular importance when short-spinning apparatuses are used, because it solves the problem of producing thermoweldable staple fibers even when operating with said apparatuses.
• the hole flow rate ranges from 0.005 to 0.18 g.min, preferably from 0.008 to 0.070 g/min, more preferably from 0.010 to 0.030 g/min.
• the fiber gathering speed ranges from 30 to 500 m/min, preferably from 40 to 250 m/min, more preferably from 50 to 100 m/min.
• the draw ratios range from 1.10 to 3.50, preferably from 1.20 to 2.50.
• the fiber cooling and solidification space at the output of the die (cooling space) is preferably greater than 2 mm, more preferably greater than 10 mm, in particular from 10 to 350 mm.
• cooling space is the distance between the die and the above mentioned air jet or flow.
• the draw temperature be lower than 100°C, in particular it should range from 15°C to 50°C.
• the spinning temperature for the above long-spinning and short-spinning apparatuses generally ranges from 240°C to 310°C, preferably from 270°C to 300°C.
• the equipment used in the process of spun-bonding normally includes an extruder with a die on its spinning head, a cooling tower, and an air suction gathering device that uses Venturi tubes.
• this device that uses air speed to control the fiber gathering speed, the filaments are usually gathered over a conveyor belt, where they are distributed forming a web for heat welding in a calender.
• the hole flow rate ranges from 0.1 to 2.0 g/min; preferably from 0.2 to 1.0 g/min.
• the space where fibers cool and solidify after leaving the die is preferably greater than 2 mm, more preferably greater than 10 mm and in particular in the range between 10 and 350 mm.
• the fibers are generally cooled by means of an air jet or flow.
• the cooling space is the distance between the die and this air jet or flow.
• the spinning temperature is generally between 230°C adn 300°C, preferably between 240°C and 280°C.
• the amount of diene in (B) is from 1% to 10% by weight.
• the heterophasic copolymers (3) are prepared according to known methods by mixing the components in the molten state, or by sequential copolymerization, and generally contain the copolymer fraction (B) in quantities ranging from 5% to 80% by weight.
• thermoweldable fibers particularly suitable for the preparation of thermoweldable fibers are the following propylene random copolymers:
• copolymers can also be used mixed with each other and/or with isotactic or mainly isotactic propylene homopolymers.
• thermoweldable fibers particularly suitable for the preparation of thermoweldable fibers are heterophasic copolymers comprising from 5% to 95% by weight of an isotactic or mainly isotactic propylene homopolymer, and/or a random propylene copolymer of the above mentioned types from a) to d), and from 95% to 5% by weight of a composition selected from:
• the above mentioned olefin polymers when used in the production of staple fibers the above mentioned olefin polymers have a Melt Flow Rate (MFR), determined according to ASTM D 1238-L, ranging from 0.5 to 100 g/10 min., preferably from 1.5 to 35 g/10 min..
• MFR Melt Flow Rate
• the above mentioned olefin polymers When used in the spun-bonding apparatuses with the process of the present invention, the above mentioned olefin polymers have preferably a MFR value between 5 and 25 g/10 min., in particular from 8 to 15 g/10 min.. These values of MFR constitute an additional distinctive feature of the process of the invention, because in conventional spun-bonding processes polyolefins have a MFR greater than 25 g/10 min.
• the olefin polymers which are subjected to spinning with either process of the present invention are stabilized with the types and quantities of stabilizers described in published European patent application 391438.
• the polyolefins to be used for spinning contain one or more of the following stabilizers:
• the above stabilizers can be added to the polyolefins by means of pelletization or surface coating, or they can be mechanically mixed with the polyolefins.
• phosphites are: tris(2,4-di-tert-butylphenyl)phosphite marketed by CIBA GEIGY under the trademark Irgafos 168; distearyl pentaerythritol diphosphite marketed by BORG-WARNER CHEMICAL under the trademark Weston 618; 4,4'-butylidenebis(3-methyl-6-tert-butylphenyl-di-tridecyl)phosphite marketed by ADEKA ARGUS CHEMICAL under the trademark Mark P; tris(monononyl phenyl)phosphite; bis(2,4-di-tert-butyl)-pentaerythritol diphosphite, marketed by BORG-WARNER CHEMICAL under the trademark Ultranox 626.
• a preferred example of phosphonites is the tetrakis(2,4-di-tert-butylphenyl)4,4'-diphenylilenediphosphonite, on which Sandostab P-EPQ, marketed by Sandoz, is based.
• the HALS are monomeric or oligomeric compounds containing in the molecule one or more substituted amine, preferably piperidine, groups.
• HALS containing substituted piperidine groups are the compounds sold by CIBA-GEIGY under the following trademarks: Chimassorb 944 Chimassorb 905 Tinuvin 770 Tinuvin 292 Tinuvin 622 Tinuvin 144 Spinuvex A36 and the product sold by American CYANAMID under the mark Cyasorb UV 3346.
• phenolic antioxidants are: tris-(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-s-triazine-2-4-6-(1H,3H,5H)-trione, marketed by American CYANAMID under the trademark Cyanox 1790; calcium bi[monoethyl(3,5-di-tert-butyl-4-hydroxy-benzyl)phosphonate];1,3,5-tris(3,5-di-tert-butyl-4- hydroxybenzyl)-s-triazine-2,4,6(1H,3H,5H)trione; 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene; pentaerythrityl-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; octadecyl 3-(3,5
• thermoweldability of fibers a nonwoven fabric is prepared from the fiber being tested by calendering under certain given conditions. Subsequently, the tension needed to tear said nonwoven fabric both in the direction parallel and transversal to the calendering is measured.
• the tension value determined in this fashion is considered a measure of the fiber thermowelding capability.
• the result is influenced substantially by the finishing characteristics of the fibers (crimping, surface finishing, thermosetting, etc.), and by the homogeneity of distribution of the fibers entering the calender. To avoid these inconveniences and obtain a more direct evaluation of the fiber thermoweldability characteristics a method has been perfected that will be described below.
• Specimens are prepared from a 400 tex roving (method ASTM D 1577-7) 0.4 meter long, made up of continuous fibers.
• thermowelding is carried out on said specimen using a Bruggel HSC-ETK thermowelding machine, operating at a plate temperature of 150°C, using a clamping pressure of 800 N and 1 second welding times.
• a dynamometer is used to measure the average strength required to separate the two halves of the roving which constitute each specimen at the thermowelding point.
• the result expressed in Newton, is obtained by averaging out at least eight measurements, and represents the thermowelding strength of the fibers.
• the polymers used in the examples to produce the fibers are the following:
• Said mechanical mixture has been obtained by introducing the components into a CACCIA speed mixer model LABO 30, and mixing for 4 minutes at 1400 rpm.
• the Chimassorb 944 is a HALS having the formula wherein n generally ranges from 2 to 20.
• the characteristics of the fibers obtained in this manner are: - single fiber count (according to ASTM D 1577-79) 1.7 dtex - weldability 4.1 N
• Example 2 The same polymer, apparatus and conditions of Example 1 are used, except that the die has 61 round holes and the output diameter is 0.4 mm.
• the characteristics of the fibers obtained in this manner are: - single fiber count 1.7 dtex - weldability 2.0 N
• the spinning conditions are as follows: - temperature 300°C - hole flow rate 0.018 g/min. - distance between the die and cooling airflow 5 mm - gathering speed 70 m/min. - draw temperature 80°C - draw ratio 1.4
• the characteristics of the fibers obtained in this manner are: - single fiber count 2.3 dtex - weldability 6.85 N
• Example 2 The same apparatus and conditions of Example 2 are used to produce staple fibers, except that one uses the polypropylene III.
• the characteristics of the fibers obtained in this manner are: - single fiber count 2.3 dtex - weldability 6.5 N
• Staple fibers are produced using the same polymer, apparatus and conditions of Example 2, except that the distance between the die and the cooling airflow is 15 mm.
• the characteristics of the fibers obtained in this manner are: - single fiber count 2.3 dtex - weldability 7.6 N
• Staple fibers are produced using the same polymer, apparatus and conditions of Example 2, except that the drawing occurs at ambient temperature.
• the characteristics of the fibers obtained in this manner are: - single fiber count 2.3 dtex - weldability 10 N
• Staple fibers are produced using the same polymer of Example 2, an industrial apparatus made up of 8 spinning units identical to the one described in Example 2, but whose dies have 5.18x104 round holes having a output diameter of 0.4 mm.
• the spinning conditions are: - temperature 285°C - hole flow rate 0.018 g/min. - distance between the die and cooling airflow 5 mm - gathering speed 64 m/min. - draw temperature 80°C - draw ratio 1.5
• the characteristics of the fibers obtained in this manner are: - single fiber count 2.3 dtex - weldability 2.35 N
• Comparative example 2 The same apparatus and conditions of Comparative example 2 are used to produce staple fibers, except that polypropylene III is used.
• the spinning conditions are: - temperature 295°C - hole draw ratio 0.024 g/min. - distance between the die and cooling airflow 5 mm - gathering speed 70 m/min. - draw temperature 80°C - draw ratio 1.35
• the characteristics of the fibers obtained in this manner are: - single fiber count 2.3 dtex - weldability 2.2 N
• fibers are prepared using a BARMAG 25 mod. 2E1/24D apparatus for spun-bonding, manufactured and sold by BARMER MASHINENFABRIK A.G. Manufacture.
• the lay out of the apparatus is as follows:
• the same polymer is used, with the same apparatus and working under the same conditions as in Example 6, except that the die has 37 circular section holes with a output hole diameter of 0.4 mm.
• the characteristics of the obtained fibers are: - single fiber count 2.2 dtex - weldability 2.04 N
• Fibers are produced with the same apparatus and working under the same conditions as in Example 6, but using polypropylene III.
• the obtained fibers have the following characteristics: - single fiber count 2.2 dtex - weldability 5.8 N
• Fibers are produced with the same polymer used in Example 8, and the same apparatus used in Example 6, but the die contains 37 holes of circular section and the output hole diameter is equal to 0.4 mm.
• the obtained fibers have the following characteristics: - single fiber count 2.2 dtex - weldability 2.1 N

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Artificial Filaments (AREA)
• Nonwoven Fabrics (AREA)
• Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)
• Multicomponent Fibers (AREA)
• Cell Separators (AREA)

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• 1994
  • 1994-06-16 FI FI942889A patent/FI942889A/fi unknown
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  • 1994-06-17 CN CN94107510A patent/CN1069352C/zh not_active Expired - Fee Related
  • 1994-06-17 TW TW083105487A patent/TW270153B/zh active
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  • 1994-06-17 DE DE69408213T patent/DE69408213T2/de not_active Expired - Fee Related
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• 1998
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