EP0843753A1 - Non tisse a fil continu - Google Patents

Non tisse a fil continu

Info

Publication number
EP0843753A1
EP0843753A1 EP96926897A EP96926897A EP0843753A1 EP 0843753 A1 EP0843753 A1 EP 0843753A1 EP 96926897 A EP96926897 A EP 96926897A EP 96926897 A EP96926897 A EP 96926897A EP 0843753 A1 EP0843753 A1 EP 0843753A1
Authority
EP
European Patent Office
Prior art keywords
blend
filaments
weight
percent
flow rate
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.)
Withdrawn
Application number
EP96926897A
Other languages
German (de)
English (en)
Inventor
Scott L. Gessner
Lloyd E. Trimble
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.)
Fiberweb North America Inc
Original Assignee
Fiberweb North America Inc
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 Fiberweb North America Inc filed Critical Fiberweb North America Inc
Publication of EP0843753A1 publication Critical patent/EP0843753A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • D04H3/00—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length
    • D04H3/08—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of strengthening or consolidating
    • D04H3/14—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of strengthening or consolidating with bonds between thermoplastic yarns or filaments produced by welding

Definitions

  • This invention relates to continuous filament nonwoven fabrics and to a process for producing such fabrics. More particularly, the present invention produces continuous filament nonwoven fabrics formed of a polymer blend which exhibit desirable strength properties, and which can be manufactured by existing equipment.
  • Nonwoven fabrics of the type to which the present invention pertains comprise a plurality of continuous filaments formed from a blend of thermoplastic polyolefin polymers randomly disposed to form a web.
  • the continuous filaments of the web are thermally bonded to one another to form a cohesive network of filaments which gives the fabric good strength and flexibility properties. Accordingly, the fabrics are suitable for use in hygiene applications, such as disposable diapers, or in medical applications, such as in disposable medical garments and the like.
  • Continuous filament nonwoven fabrics of this type may be produced by the well-known "spunbond” process in which molten thermoplastic polymer is extruded from a spinneret to form an array of continuous filaments, the filaments are attenuated and drawn pneumatically, they are deposited on a collection surface to form a web, and the filaments are thermally bonded to form a strong, coherent fabric.
  • the continuous filaments are attenuated and drawn by passing through venturi tubes. Pressurized air supplied to the venturi tubes accelerates the filaments to a linear velocity on the order of 3500 meters per minute, causing attenuation and drawing of the filamentary polymer extrudate.
  • the rapidly moving filaments are discharged from the venturi tubes and deposited on a moving belt or wire to form a web.
  • the filaments of the web are then bonded at filament intersections to render the web coherent and impart strength to the nonwoven fabric.
  • the bonding may, for example, be carried out by passing the web of filaments through the nip of a pair of cooperating heated calender rolls. One of the calender rolls may be engraved with a pattern of raised areas or lands so that the bonding forms individual discrete bond areas throughout the fabric.
  • filaments are accelerated through a slot from an open-air quench chamber, by means of a vacuum from beneath the moving belt .
  • the continuous filaments are attenuated and quenched primarily above the slot, but continue to be pulled to the wire by means of reduced pressure below the wire. Filaments velocities range from several hundred meters per minute to greater than 1000 meters per minute.
  • the filaments of the web are then bonded at filament intersections similar to other spunbond processes.
  • the freshly extruded filaments of thermoplastic polymer are attenuated and drawn by an attenuator device in the form of an elongate slot rather than by individual venturi tube attenuators.
  • the slot extends in the cross-machine direction typically the full width of the nonwoven fabric. Air is caused to move downwardly through the elongate slot, entraining the filaments and causing them to be attenuated and drawn before being discharged from the slot and deposited on a moving belt or wire.
  • This type of "slot-draw" system accelerates the filaments to speeds typically in excess of 1500 meters per minute, with higher filament velocities (e.g., greater than 10,000 meters per minute) being possible.
  • the above-noted spunbond process for producing continuous filament nonwoven fabrics is distinctly different in a number of respects from other conventional manufacturing processes for producing nonwoven fabrics, such as staple fiber nonwovens for example. Very significant differences reside in the conditions under which the filaments are formed and deposited to form a nonwoven fabric.
  • the linear filament velocity and filament melt draw conditions are much more severe in a spunbond process than, for example, in the manufacture of melt-spun filaments for staple fiber nonwoven webs.
  • the filaments are typically drawn mechanically, e.g.
  • spunbond processes generally spin at velocities to achieve the desired denier in the web
  • staple processes spin higher deniers which are then drawn in separate downstream processes to the final desired denier. Therefore even when filament velocities are roughly equivalent between spunbond and staple processes, spunbond processes are producing finer deniers with greater air turbulence and force variation than in staple processes.
  • melt-spun filaments for staple fiber nonwovens are typically "cold drawn” to the desired denier, chopped into staple fibers, and the staple fibers are formed into nonwoven webs in a separate subsequent operation, typically by carding or air laying.
  • the webs can be bonded together either with chemical binders or by thermal bonding, e.g., calendering.
  • the spunbond process is more complex than staple fiber nonwoven processes since the formation of the filaments, drawing of the filaments to fine deniers, quenching of the filaments, separation of the filaments, and formation of the filaments into a web occur in a continuous operation. Because of the integrated nature of the operation, the selection of the polymer is significant in achieving good processability. The selected polymer should have desirable processing attributes which may sometimes conflict. Because air is used to draw the filaments, a polymer with an optimal melt tension should be selected to enable drawing of the filaments to a desired fineness at reasonable air pressures and volumes. Excessive tension or elasticity will result in higher deniers and an increased number of filament breaks resulting in molten droplet contamination of the forming wire.
  • melt tension typically does not directly affect filament denier in staple fiber processes since the filaments are cold drawn utilizing mechanical godets and rolls.
  • filament denier is primarily determined by the capillary throughput relative to the take-up roll velocity.
  • a number of polymer, filament, and processing characteristics have been found to impact these steps including capillary throughput, quench and smoke removal, flow of entrained air, melt tension, filament surface properties, filament flexibility, denier, air/filament velocity ratio, static charge, forming system air flow, and wire design. Many of these factors are interdependent.
  • the spunbonding process offers advantages relative to staple fiber processes.
  • the integrated process of spinning, web formation, and bonding is less costly than a multiple step staple fiber operation.
  • the continuous filaments of the spunbond fabrics tend to produce stronger fabrics than staple fiber products made from comparable polymers.
  • An important factor in developing strength in a spunbonded or staple fabric is the bonding operation. This is especially true with respect to staple fabrics.
  • the discontinuous fiber of carded staple nonwovens are more dependent upon bonding for the development of tensile strength properties.
  • Bonding serves to join the filaments of the web into a cohesive network. The bonds assist in the transfer of a load or stress to a larger population of filaments. The greater number of filaments which contribute to load bearing, in combination with individual filament strength or toughness, the stronger the fabric.
  • Process conditions during filament spinning also greatly affect resulting nonwoven fabric strength properties. Especially significant are factors which impact polymer melt flow rate such as temperature.
  • a particularly troubling technical problem relates to the careful control required to minimize polymer breakdown, especially in the processing of polyolefins at high commercial speeds.
  • the rheology of such "minimally- process-altered" polymer is suitable for stable spinning usually over a limited range of melt temperatures.
  • Employing high temperatures i.e., over 260°C
  • MWD molecular weight and molecular weight distribution
  • the combination of "cracked” polymer with high temperature can adversely affect web formation.
  • poor spinning characterized by limp spinline, filament collisions, and ductile failure is also experienced.
  • the present invention is directed to the production of continuous filament nonwoven fabrics spun at high velocities under high temperature conditions.
  • the process of the invention provides filaments which exhibit high drawability and minimal association or bundling. Accordingly, good filament distribution is realized along with a uniform, coherent, strong fabric.
  • a blend of thermoplastic polymers can be melt spun under conditions which are responsible for controlled oxidation of the fiber outer surface so that the resulting fibers are capable of forming strong interfilamentary bonds.
  • these conditions include selecting a polymer blend which is higher in molecular weight (MW) than is typically used for a low temperature process or given product, maintaining the polymer blend in the extruder and at the spinneret at a temperature higher than usually employed for a lower MW polymer or product, and controlling the extrusion conditions (e.g. spinneret capillary diameter, polymer blend throughput) and quench conditions, depending upon polymer molecular and rheological characteristics, as well as the level of stabilizer in the polymer blend, in order to promote a controlled oxidative degradation, and consequent reduction in molecular weight, in a zone at the outer surface of the filaments.
  • MW molecular weight
  • the blend comprises at least two thermoplastic polymers with one of the polymers being a polyolefin.
  • one of the polymers comprise a majority of the blend by weight.
  • a propylene polymer i.e., a polymer composed of greater than 40% weight propylene moieties, such as a polypropylene homopolymer, copolymer, or terpolymer
  • An ethylene-propylene copolymer having a melt flow rate of 15 g/10 min. or lower is another preferred majority component.
  • blends including, for example, polymers which are soft and elongatable, including an ethylene polymer. Numerous other components can be employed as well, such as polybutene and propylene copolymers.
  • a preferred blend employing a soft, elongatable polymer comprises between about 1 to 50 percent by weight of ethylene polymer and about 99 to 50 percent by weight polypropylene, with high density polyethylene more preferably being utilized.
  • blends and compositions may be employed and are as follows : 1 to 50 percent by weight polybutene and 99 to 50 percent by weight polypropylene; 1 to 50 percent by weight of ethylene polymer and 99 to 50 percent by weight of an ethylene-propylene copolymer having a melt flow rate of 15 g/10 min. or less; and 1 to 50 percent by weight polybutene and 99 to 50 percent by weight of ethylene- propylene copolymer having a melt flow rate range as above.
  • the blends of the invention may also employ more than two polymers; for example, three and four polymer components may be added to a two component blend to modify blend compatibility, viscosity, or polymer crystallinity.
  • a preferred three component blend comprises 1 to 50 percent by weight of polypropylene having a melt flow rate of 35 g/10 min. or less with the balance of the blend comprising a propylene copolymer and an ethylene polymer.
  • a continuous filament nonwoven fabric is produced by forming a melt blend of at least two thermoplastic polymers wherein at least one is a polyolefin, and preferably containing a propylene polymer of melt flow rate of 35 or lower as the majority component, extruding the melt blend through a spinneret to form continuous filaments at a temperature and throughput such that oxidative degradation of at least one polymer component of the outer sheath portion of the filaments occurs, preferably at a temperature above 250°C, and most preferably between 270°C and 320°C and at a throughput preferably greater than about 0.1 gram per minute per hole, and most preferably between about 0.5 to 5.0 grams per minute per hole, pneumatically accelerating the filaments, preferably at speeds in excess of
  • the invention provides a nonwoven fabric comprising drawn continuous filaments of a thermoplastic polymer blend, the filaments being randomly arranged to form a web.
  • a multiplicity of thermal bonds serve to bond the filaments together to form a coherent continuous filament nonwoven fabric.
  • Oxidative degradation of at least one polymer component in the outer sheath portion of the filaments is evidenced by a relative reduction in weight average molecular weight of the polymer component compared to the polymers present in the inner fiber portion.
  • the MFR of the web is preferably between 5 and 100, and most preferably between 5 and 35 g/10 min.
  • a uniform, coherent spunbonded fabric is obtained displaying excellent strength, toughness, elongation, and bonding properties. Accordingly, the nonwoven fabric is especially desirable in numerous applications including those involving medical, hygiene, and industrial.
  • the present invention is directed to the production of continuous filament nonwoven fabrics from blends of thermoplastic polymers including at least one polyolefin polymer derived by polymerization from relatively simple olefins. More particularly, the invention is primarily directed to the formation of spunbonded nonwoven fabrics from blends comprised of a propylene polymer of low melt flow rate.
  • polymer is used in a general sense, and is intended to include homopolymers, copolymers, grafted copolymers, and terpolymers. In general, the invention can be effectively practiced with starting polymers of a wide variety of different distributions.
  • blend is also used generally herein, and is intended to include immiscible and miscible polymer blends. For the purposes of the invention, the polymers are considered to be “immiscible” if they exist in separate, distinct phases in the molten state; all other blends are considered to be “miscible” .
  • the polymer blend which forms the fabric has sufficiently low melt flow rate (MFR) such that the resulting filament web has an MFR between 5 and 100 g/10 min. , and more preferably between 5 and 35 g/10 min.
  • MFR melt flow rate
  • the MFR is determined according to ASTM test procedure D-1238 and refers to the amount of polymer (in grams) which can be extruded through an orifice of a prescribed diameter under a mass of 2.16 kg at 230 °C in 10 minutes.
  • the MFR values as used herein have units of g/10 min. or dg/min.
  • the polymers can encompass a variety of molecular weight distributions.
  • molecular weight distribution is defined as the weight average molecular weight of the dominant polymer (i.e., the polymer which comprises the greatest percentage of the blend) divided by the number average molecular weight of the dominant polymer. Both molecular weight determinations used in calculating the MWD are made in accordance with standard procedures.
  • the MWD of the dominant thermoplastic polymer in the blend is less than 5.5.
  • the preferred MWD range is applicable to the polymers just prior to being drawn into filaments and to the polymers present in the filaments of the formed web.
  • the polymers which comprise a miscible or immiscible blend can be combined in manners utilized in conventional extrusion processes.
  • the polymers can be dry blended in any acceptable form and heated in the barrel of an extruder to form a melt blend.
  • a suitable level of mixing is necessary such that the polymers which form an immiscible blend become adequately dispersed.
  • sufficient mixing of the polymer components may be achieved in the extruder as the polymers are converted to the molten state, although it may be preferable to use an additional mixing zone or step.
  • At least two thermoplastic polymers will be present in the blend, in which at least one is a polyolefin polymer.
  • a preferred blend comprises two polymers, with one being the majority component by weight and the other being the minority component.
  • Various polymers can be utilized as the majority component, including but not limited to, polyolefins such as a propylene polymer (e.g., homopolymer, copolymer, or terpolymer) , a polymethyl pentene (TPX) , a polymethyl pentene copolymer, and an ethylene- propylene copolymer.
  • Polycondensate polymers may also be used such as polyethylene terephthalate, polybutylene terephthalate, or a polyamide (e.g., nylon) .
  • Various polymers can be utilized as minority components in the blend, and preferably, for example, those which are soft and elongatable.
  • soft, elongatable polymers include metallocene polyolefin polymers, elastomers, and plastomers.
  • Preferred soft, elongatable polymers include standard ethylene polymers made by Ziegler-Natta or high pressure techniques as well as commercially suitable soft, elongatable polymers such as the Catalloy polyolefins available from Himont Incorporated, the Exact Series of polymers available from the Exxon Chemical Company, and the Affinity polymers available from the Dow Chemical Company.
  • the minority component can also include well known polymers which are miscible or soluble with the majority component including, for example, a polybutene or another propylene polymer, copolymer, or terpolymer differing in either chemistry or molecular characteristics (e.g., molecular weight or molecular weight distribution) from the low MFR propylene polymer employed as the majority component. Ethylene-propylene copolymers may also be used.
  • a propylene polymer e.g., polypropylene homopolymer, copolymer, or terpolymer having a melt flow rate of less than 35 is a preferred majority component in the blend. More preferably, the propylene polymer has a melt flow rate of less than 15.
  • a preferred immiscible blend comprises about 1 to 50 percent by weight of an ethylene polymer and 99 to 50 percent by weight propylene polymer. More preferably, the blend comprises about 2 to 20 percent by weight of polyethylene and about 98 to 80 percent by weight polypropylene.
  • High density polyethylene is preferably employed in the above compositions.
  • one blend comprises polybutene from about 1 to 50 percent by weight and 99 to 50 percent by weight propylene polymer having the MFR values listed above, and, more preferably, between about 2 to 10 percent by weight polybutene and 98 to 90 percent by weight polypropylene.
  • Other preferred blends comprise an ethylene-propylene copolymer as the majority component.
  • one blend comprises an ethylene polymer from about 1 to 50 percent by weight and an ethylene-propylene copolymer from about 99 to 50 percent by weight and having a melt flow rate of less than 15 g/10 min.
  • the blend comprises between 2 to 10 percent by weight of ethylene polymer and 98 to 90 percent by weight ethylene-propylene copolymer.
  • Another preferred blend comprises polybutene from about 1 to 50 percent by weight and 99 to 50 percent by weight ethylene-propylene copolymer, and most preferably, between 2 and 10 percent by weight polybutene and 98 to 90 percent by weight ethylene- propylene copolymer.
  • Specific blend compositions utilizing polycondensate polymers may be also employed in accordance with the invention.
  • PET polyethylene terephthalate
  • PET may be blended in any ratio with a polyolefin.
  • PET may comprise 50 to 99 percent by weight of the blend while the other polymer comprises the balance of the blend (1 to 50 percent by weight) and may be selected from any one of the following: an ethylene polymer, a propylene polymer, an ethylene-propylene copolymer, a methyl pentene polymer and polybutene.
  • polyamide (PA) may be blended in any ratio with a polyolefin.
  • PA may comprise between 50 and 99 percent by weight of the blend while tho other polymer comprises the balance of the blend (1 to 50 percent by weight) and may be selected from those polymers listed above. Blends with more than two polymers may also be utilized, including those with three and four polymer components.
  • Both immiscible and miscible polymers may be added to a two component blend to impart additional properties or benefits with respect to blend compatibility, viscosity, polymer crystallinity or phase domain size.
  • a preferred category of blends are those comprised of a dominant low MFR propylene polymer component, a separate ethylene component, and at least one additional polymer component selected from the following: polybutenes (e.g., Shell Duraflex polymers and copolymers), Catalloys (i.e., co- and ter- polymers of propylene) , polyvinyl acetates, acrylates (e.g., polymethacrylate, polymethylmethacrylate) , acrylic acid copolymers, grafted copolymers of ethylene or propylene (e.g., maleic anhydride grafted onto polyethylene) , polylactic acids, and thermoplastic starch based polymers.
  • polybutenes e.g., Shell Duraflex polymers and cop
  • a preferred blend includes 5 to 50 percent by weight of a propylene co- or ter- polymer with the balance comprising polypropylene having a melt flow rate of less than 35 g/10 min. and polyethylene. Most preferably, the blend comprises between 2 and 20 percent by weight of propylene co- or ter- polymer with the balance comprising polypropylene and polyethylene. Since the polymer blends employed in the invention will almost universally undergo some level of degradation in the extrusion process, stabilizers and antioxidants are conventionally added to the polymer blend. The level and kind of stabilizer/antioxidant can affect the degree to which the blend undergoes degradation.
  • the stabilizer/ antioxidant concentrations in the polymer blend typically may range from 0-1% by weight. When present, the antioxidant/stabilizer is preferably within a range of about .005%-0.5%.
  • Antioxidant/ stabilizer compositions which can be used include at least one composition selected from the group consisting of organic phosphites, organic phosphonites, hindered phenols, and hindered amines.
  • examples of such compositions include phenylphosphites such as Sandostab PEP-Q from Sandoz Chemical Co., distearyl pentaerythritol diphosphite (DSTDP) ; phenol substituted nitrogen heterocyclic compounds, e.g. Goodrite 3114; N,N'bis-piperidinyl diamine-containing compositions; hindered amine stabilizers such as 1, 2, 2, 6, 6-pentamethyl piperidines. More specific examples of antioxidant/stabilizer compositions which may be used in the polymer blends for this invention are disclosed in published European Patent Application, EP 391,438, which is incorporated herein by reference.
  • additives conventionally used in the production of continuous polymer filaments can also be incorporated in the polymer blend such as antiblocking agents, impact modifiers, plasticizers, UV stabilizers, pigments, delusterants, lubricants, wetting agents, antistatic agents, nucleating agents, water and alcohol repellents, etc, in the conventional amounts, which are typically no more than about 10% by weight.
  • Polymeric additives may also be used in conjunction with the blends which impart specific benefits to either processing and/or end use.
  • plastomers, compatibilizers, viscosity modifiers or diluents which affect phase domain size or crystallinity may be included.
  • the polymer blend continues to undergo thermo-oxidative and/or photo-oxidative degradation after exiting the extrusion die.
  • an oxidation reaction occurs on the surface of the molten filaments, which forms an oxidized sheath on the cooled filaments . Oxidation of the filament surface activates the surface so that it assists in bonding, lamination and retention of topical additives, such as surfactants, water or alcohol repellents, printing inks, and the like.
  • the process parameters which control the polymer blend surface oxidation include the following:
  • the oxidation reaction is complex, since the key process variables are constantly changing in any moderate to high speed spunbonding operation. For example, filament temperature (and therefore time at temperature) , density and diameter (and therefore surface to volume ratio) are changing constantly and non-linearly between the capillary exit and the freeze point of the spinline.
  • the concentration of active stabilizer changes as it reacts with diffused oxidizer.
  • the polymers in the blend are constantly changing as they react, are drawn, and cool. However, these process parameters can be manipulated in order to achieve a desired controlled degree of surface oxidation for various polymer blends with various stabilizer levels.
  • capillary diameters At constant capillary throughput, larger capillary diameters, or capillary cross-sectional areas in the case of non-cylindrical capillaries, will decrease the polymer blend linear velocity in and just beneath the die. This increase in polymer blend residence time in and near the die, where the polymer blend temperature is at its peak, has a significant affect on the extent of oxidation. While smaller diameter capillaries may create higher die swell, which in turn decreases the linear velocity, this effect tends to reduce the surface to volume ratio. Therefore capillary diameters must be balanced with other materials and process conditions. Larger diameters will, however, tend to increase the extent of oxidation.
  • the spinneret capillaries are from 0.4 to 1.2 mm, and most preferably between about 0.6 to 1.0 mm, or have a cross-sectional area from about 0.2 to 1.2 mm 2 .
  • Capillary throughput affects the polymer blend linear velocity just beneath the die, and can therefore affect the extent of oxidation for reasons similar to those given above. Throughput also affects the extent of oxidation indirectly, by having an affect on the total mass of the material to be oxidized and the die swell. Higher polymer blend throughput, in general, will tend to reduce the extent of oxidation.
  • the polymer blend throughput is within the range of 0.1 to 5 grams/minute/hole for spinning speeds of about 100 to 10,000 meters/minute, and most preferably from 0.5 to 2.0 grams/minute/hole for spinning speeds of about 1500 to 5000 meters/minute.
  • the concentration of oxygen or other oxidizing gases just below the die and in the draw zone will affect the rate and extent of oxidation. If the cooling rate of the extruded molten filament is retarded, the time it spends at elevated temperature is increased, giving it more time to oxidize.
  • Draw zone conditions e.g. quench temperature, quench and smoke removal flow rate
  • Draw rate can affect oxidation in several ways. Higher draw rates increase the surface to volume ratio of the molten polymer blend strand, by rapidly decreasing filament diameter. However, the increased surface to volume ratio also increases the rate at which the filament is quenched.
  • more highly stabilized polymer blends will require one or more of the following process adjustments: higher extrusion temperature; higher shear extrusion; longer extrusion resident time,- higher melt temperature at the die; larger capillary diameter; delayed quenching.
  • higher extrusion temperature higher shear extrusion
  • longer extrusion resident time longer melt temperature at the die
  • larger capillary diameter delayed quenching.
  • die temperature and capillary diameters would be similar to those of less stabilized polymers.
  • nonwoven fabrics described herein can be used in various applications where spunbonded nonwoven fabrics are found useful. Especially preferred are fabrics formed of fine denier continuous filaments (i.e., 5 or below), which are desirable in many areas including medical applications, hygiene, agricultural, industrial fabrics, and the like. As an example, such fabrics serve as an effective liner or top sheet component in disposable absorbent articles such as diapers, incontinence briefs, and feminine hygiene products .
  • the fabrics may also be formed and/or laminated to at least one other component to form a composite nonwoven fabric which can be effectively employed in a disposable absorbent article.
  • the spunbond fabric may be formed and/or laminated to at least one other component selected from the group consisting of a carded nonwoven fabric, a spunbonded nonwoven fabric, a meltblown nonwoven fabric, a net, and a film.
  • a carded nonwoven fabric a spunbonded nonwoven fabric
  • a meltblown nonwoven fabric a meltblown nonwoven fabric
  • a net a net
  • a film a film
  • Comparative Examples 1-4 For the purposes of comparing Examples 5-16, Examples 1-4 were prepared as outlined below. Examples 1 and 2 represent standard hygiene fabrics prepared from traditional spunbond polymers. Examples 3 and 4 represent fabrics comprising a blend spun at conventional low temperatures. Spinning performance and fabric properties are reported in Table I .
  • Example 1 A 35 MFR (CR Grade) polypropylene (Exxon)
  • the spinneret employed had 1134 holes, each with a 0.4 mm capillary diameter.
  • the melt temperature near the die was measured to be about 250°C.
  • a 50 cc/revolution pump was used at a speed of 27 RPM, producing a throughput of about 0.9 grams per minute per hole.
  • the filaments were extruded into a 1 meter single quench zone equipped with temperature and flow control .
  • the filaments were thereafter directed through Lurgi attenuators operating with compressed air at a pressure of 20 bar.
  • the filaments were deposited onto a moving collection surface such that a fabric resulted using an oil heated calender system, equipped with parallel embossed and smooth rolls which formed a nip.
  • the embossed roll surface temperature was 147°C and a smooth roll surface temperature of 146°C.
  • a 35 MFR (CR) PP polypropylene (Aristech 380B) was melt spun into continuous filaments utilizing the system and under the conditions described in Example 1.
  • a blend of 10% by weight 400 MFR polypropylene (PP, Himont HH 441) and 90% by weight polypropylene (Aristech 380B) was formed using a Conair hopper additive system. The blend was melt spun into continuous filaments utilizing the system and under the conditions described in Example 1.
  • Example 4 A blend of 5% by weight high density polyethylene (Dow HDPE 08065E, 8 MI, 0.965 g/cc, 130°C melt, temp.) and 95% by weight polypropylene (Exxon 3445, 35 MFR, 0.9 g/cc, 165°C melt, temp.) was formed using a Conair hopper system and spun into continuous filaments utilizing a similar system to Example 1 with the following exceptions: (1) the extruder zones were maintained at a temperature profile of
  • melt block, pump, and die were maintained at a temperature of 245°C.
  • Example 5 A blend of 10% by weight 400 MFR polypropylene (Himont HH 441) and 90% by weight polypropylene (Appryl 3130) was formed using a Conair hopper additive system. The blend was melt spun into fine denier filaments utilizing the system described in Example 1 with the following exceptions: (1) the extruder zones were maintained at a temperature profile of 270/270/280/290/285°C, (2) the spinneret used had 756 holes, each with a 0.9mm capillary diameter, (3) the speed of the pump was 18 RPM, and (4) the compressed air utilized in the Lurgi attenuators was 15 bar.
  • a blend of 5% by weight high density polyethylene (Dow HDPE 08065E) and 95% by weight polypropylene (Appryl 3130) was formed using a Conair hopper additive system and spun into continuous filaments on a 60 mm diameter, 5 heating/cooling zone, 30:1 1/d extruder, equipped with a barrier flighted, high work screw designed for polypropylene extrusion, with a pin mixing head.
  • the extruder zones were maintained at a temperature profile as follows: 275/265/290/295/290.
  • the melt block, pump and die were maintained at a temperature of 290°C.
  • the spinneret employed had 756 holes, each with a 0.65mm capillary diameter.
  • the melt temperature of the polymer near the die was measured to be about 275°C.
  • a 50 cc/revolution pump was used at a speed of 18 RPM, producing a throughput of approximately 0.9 g/m/h.
  • the filaments were extruded into a 1 meter single quench zone equipped with temperature and flow control.
  • the filaments were thereafter directed through Lurgi attenuators operating with compressed air at a pressure of 13 bar.
  • the filaments were deposited onto a moving collection surface to form a web.
  • the web was bonded such that a fabric resulted using an oil heated calender system, equipped with parallel embossed and smooth rolls which formed a nip.
  • the embossed roll surface temperature was 148°C and a smooth roll surface temperature of 147°C.
  • Examples 7-8 represent fabrics formed of polyethylene and polypropylene.
  • Example 7 a blend of 4% by weight high density polyethylene (Dow HDPE 08065E, 8 MI, 0.965 g/cc, 130°C melt temp.) and 96% by weight polypropylene (Appryl 3130) was formed using a Conair hopper additive system and spun into continuous filaments on a 60 mm diameter, 5 heating/cooling zone, 30:1 1/d extruder, equipped with a low work, single flighted, 'Nylon' screw. The extruder zones were maintained at a temperature profile of
  • the melt block, pump, and die were maintained at a temperature profile of 300/300/300/295°C.
  • the spinneret employed had 756 holes, each with a 0.65mm capillary diameter.
  • a 70 cc/revolution pump was used at a speed of 11.4 RPM, producing a constant throughput of approximately 0.8 g/m/h.
  • the filaments were extruded into a 1 meter single quench zone equipped with temperature and flow control .
  • the filaments were thereafter directed through Lurgi attenuators operating with compressed air at a pressure of 20 bar.
  • the filaments were deposited onto a moving collection surface to form a web.
  • the web was bonded such that a fabric resulted using an oil heated calender system.
  • Example 8 8% by weight high density polyethylene was blended with 92% by weight Appryl 3130 under conditions employed in Example 7.
  • Examples 9-11 represent fabrics comprising blends of polybutene and polypropylene.
  • Example 9 a blend of 10% by weight polybutene homopolymer (Shell Duraflex DP0300, 4 MI, 0.915 g/cc, 125°C melt temp.) and 90% by weight polypropylene (Appryl 3130) was formed and melt spun into filaments utilizing the system described in Example 7 with the following exceptions: (1) the extruder zones were maintained at a temperature profile of 250/270/290/290/290°C and (2) the melt block, pump, and die were maintained at a constant temperature of 290°C.
  • Example 10 10% by weight polybutene/ethylene copolymer (Shell Duraflex DP8340, 4.0 MI, 0.908 g/cc, 116°C melt temp.) was blended with 90% by weight Appryl 3130 under conditions similar to those in Example 9.
  • Example 11 10% by weight polybutene homopolymer (Shell Duraflex DP0800, 200MI, 0.915 g/cc, 125°C melt temp.) is blended with 90% by weight Appryl 3130 under conditions similar to Example 10 with the exception that the extruder zones were maintained at a temperature profile of 280/270/280/290/290°C. Spinning performance and fabric properties are reported in Table II. As shown, the samples yielded superior tensile strength values relative to Examples 1-4, along with favorable elongation values. Good spinnability of the filaments in both examples was also observed along with good web formation.
  • Examples 12-16 represent fabrics comprising blends of heterophasic propylene copolymers (e.g., Catalloys produced by Himont) and polypropylene.
  • heterophasic propylene copolymers e.g., Catalloys produced by Himont
  • polypropylene e.g., polypropylene
  • Example 12 a blend of 10% by weight of (i.e., Catalloy produced by Himont) Himont KS054P. (3.5 MI) and 90% by weight polypropylene (Appryl 3130) was formed and melt spun into filaments utilizing the system described in Example 7 with the following exceptions: (1) the extruder zones were maintained at a temperature profile of 270/280/290/300/300°C and (2) the filter/piping/static mixer/pack zones were maintained at a temperature profile of 300/300/300/290°C. In Example 13, 10% by weight of Himont KS059
  • Example 14 15% by weight of Himont KS059 was blended with 85% Appryl 3130 under conditions similar to Example 12 with the following exceptions:
  • Example 15 (1) the extruder zones were maintained at a temperature profile of 260/280/290/300/300°C and (2) the melt block, pump, and die were maintained at a temperature profile of 300/300/300/290°C.
  • Example 15 20% by weight of Himont KS059 was blended with 80% Appryl 3130 under conditions similar to Example 1 .
  • Example 16 10% by weight of Himont KS057P was blended with 90% by weight of Appryl 3130 under conditions similar to Example 12 with the following exceptions: (1) the extruder zones were maintained at a temperature profile- 250/270/290/290/290°C and (2) the melt block, pump, and die was maintained at a temperature of 290°C.
  • a blend of 4% by weight of high density polyethylene (Dow HDPE 08065E) and 96% by weight polypropylene (Appryl 3130) was formed using a Conair hopper additive system and melt spun into continuous filaments on a 90 mm., 32:1 1/d extruder, equipped with a barrier flighted, low work screw with a pin mixing head.
  • the extruder zones were maintained at a temperature profile as follows: 270/290/300/300/300°C.
  • the melt block, pump, and die were maintained at a temperature of 290°C.
  • the spinneret employed has 1421 holes, each with a 0.65 mm. capillary diameter.
  • a 46 cc/revolution pump was used producing an output of 0.8 grams/minute/hour.
  • the filaments were extruded into a 1 meter single quench zone equipped with temperature and flow control .
  • the filaments were thereafter directed through a slot attenuator operating with compressed air.
  • the filaments were deposited onto a moving collection surface such that a fabric resulted using an oil heated calender system, equipped with parallel embossed and smooth rolls which formed a nip.
  • Examples 18-20 represent fabrics comprising three component blends of a heterophasic propylene copolymer, high density polyethylene, and polypropylene.
  • a blend of 10% by weight of Himont KS059P, 4% by weight of HDPE (Dow 08065E) , and 86% by weight of Appryl was formed and melt spun into filaments under conditions similar to Example 17.
  • Example 19 the same percentage of Dow 08065E HDPE and Himont KS059P was blended with 86% by weight of polypropylene (Himont HOXP 621, 13 MFR) and melt spun into filaments under conditions similar to Example 19 with the following exceptions: (1) the extruder zones were maintained at a temperature profile of 270/280/290/290/290°C and (2) the melt block pump, and die were maintained at a temperature profile of 290/280°C.
  • Example 20 8% by weight of Dow 08065E HDPE, 10% by weight of Himont HOXP 621, and 82% by weight of Himont KS059P were blended and melt spun into filaments under conditions similar to Example 19.
  • Examples 21 and 22 represent fabrics comprising blends of a heterophasic propylene copolymer (Himont KS059P) and polypropylene (Appryl 3130) .
  • Himont KS059P heterophasic propylene copolymer
  • Appryl 3130 polypropylene
  • Example 21 a blend of 10% by weight of Himont KS059P was formed with 90% by weight of Appryl 3130 and melt spun into continuous filaments utilizing a system similar to Example 19.
  • Example 22 a blend of 20% by weight of the Himont KS059P was formed with 80% by weight of Appryl 3130 and melt spun into continuous filaments using a system similar to Example 21.
  • Examples 23 and 24 represent fabrics comprising blends of polybutenes (i.e., a homopolymer and a copolymer) and Himont HOXP 621 polypropylene.
  • a blend of 10% by weight of polybutene copolymer with ethylene (Shell DP 8340, 4 MI) and 90% by weight of Himont HOXP 621 was formed and melt spun into continuous filaments utilizing a system similar to that used in Example 22.
  • Example 24 a blend of 10% by weight of polybutene homopolymer (Shell DP 0400, 20 MI) and 90% by weight of Himont HOXP 621 was formed and melt spun into continuous filaments utilizing a system similar to that used in Example 20.
  • Example 23 displayed good results in both categories, while Example 24 showed excellent spinning, but only acceptable web formation.
  • Example 25 A four component blend was formed comprising: 4% by weight polyethylene, 10% by weight Himont KS059P, 20% Appryl 3130, and 66% by weight of ethylene propylene copolymer (Exxon 18131-122-001, 10 MFR) .
  • the formed blend was melt spun into continuous filaments using similar conditions as employed in Example 24 with the following conditions: (1) the extruder block was TABLE I:
  • the spi ⁇ nability was assigned a rating according to the following spin rating system: (6) SPIN RATING SYSTEM (1-8)'
  • the spinnability was assigned a rating according to the following spin rating system' (6) SPIN RATING SYSTEM (1-8)-

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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)

Abstract

La présente invention a pour objet un procédé de fabrication d'un non tissé à fil continu réalisé dans des conditions de fabrication qui modifient les caractéristiques en surface du fil et du tissu. Un mélange de polymères thermoplastiques, dont au moins un est un polymère polyoléfinique contenant un constituant polymère principal à faible vitesse de fluage, est extrudé à travers une filière chauffée de manière à provoquer une oxydation contrôlée de la surface du fil d'au moins un des constituants, ce qui permet d'obtenir un collage efficace. Au cours du processus de filature, les fils continus se révèlent être d'une bonne étirabilité et sont bien répartis sur la surface de collecte. De préférence, les fils sont étirés pour obtenir un denier fin (c'est-à-dire 5, voire moins). Le tissu non tissé à fil continu ainsi obtenu possède les propriétés de résistance souhaitées grâce à une résistance de liaison entre les fils élevée.
EP96926897A 1995-08-11 1996-08-07 Non tisse a fil continu Withdrawn EP0843753A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US51400995A 1995-08-11 1995-08-11
US514009 1995-08-11
PCT/US1996/012732 WO1997007274A1 (fr) 1995-08-11 1996-08-07 Non tisse a fil continu

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EP0843753A1 true EP0843753A1 (fr) 1998-05-27

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EP96926897A Withdrawn EP0843753A1 (fr) 1995-08-11 1996-08-07 Non tisse a fil continu

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EP (1) EP0843753A1 (fr)
AU (1) AU6690596A (fr)
BR (1) BR9610213A (fr)
MX (1) MX9801185A (fr)
WO (1) WO1997007274A1 (fr)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0891433B1 (fr) 1996-03-29 2003-05-07 FiberVisions, L.P. Fibres en polypropylene et articles fabriques a partir de telles fibres
US5985193A (en) * 1996-03-29 1999-11-16 Fiberco., Inc. Process of making polypropylene fibers
US6248833B1 (en) † 2000-02-29 2001-06-19 Exxon Mobil Chemical Patents Inc. Fibers and fabrics prepared with propylene impact copolymers
EP2025712A1 (fr) * 2007-08-09 2009-02-18 Borealis Technology Oy nouvelles compositions de polyoléfine et bandes, fibres et filaments étirés fabriqués à partir de celles-ci
EP3488039A4 (fr) * 2016-07-22 2019-07-03 ExxonMobil Chemical Patents Inc. Fibres non tissées de polypropylène, tissus et procédés de fabrication associés

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Publication number Priority date Publication date Assignee Title
IT1229141B (it) * 1989-04-06 1991-07-22 Himont Inc Poliolefine atte alla filatura e fibre termosaldabili da esse ottenute.
FI112252B (fi) * 1990-02-05 2003-11-14 Fibervisions L P Korkealämpötilasietoisia kuitusidoksia
SG50447A1 (en) * 1993-06-24 1998-07-20 Hercules Inc Skin-core high thermal bond strength fiber on melt spin system
US5554435A (en) * 1994-01-31 1996-09-10 Hercules Incorporated Textile structures, and their preparation
KR100408353B1 (ko) * 1994-12-19 2004-03-09 헤르큘레스 인코포레이티드 고강도부직물용섬유의제조방법,및이로부터제조된섬유및부직물

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Title
See references of WO9707274A1 *

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WO1997007274A1 (fr) 1997-02-27
AU6690596A (en) 1997-03-12
MX9801185A (es) 1998-07-31

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