Bicomponent binder fiber

Abstract

Disclosed herein are bicomponent fibers comprising a first component and a second component. The first component comprises 70-97.5 wt. % polyethylene having a melt index, based on the weight of the first component, and 2.5-30 wt. % maleic anhydride-grafted polyethylene, based on the weight of the first component, the maleic anhydride-grafted polyethylene having a maleic anhydride level and melt index of 0.50-3.00 wt. % based on the weight of the maleic anhydride-grafted polyethylene. The ratio of the melt index of the polyethylene to the melt index of the maleic anhydride-grafted polyethylene is less than 1.25. The first and second components may be part of a sheath-core, eccentric sheath-core, islands-in-the-sea, side-by-side, or segmented pie structure. The disclosed bicomponent fibers can be used to produce nonwoven materials. These bicomponent fibers can produce nonwoven fabrics with improved bonding efficiency and better mechanical strength due to the high surface concentration of maleic anhydride, as evidenced by higher surface oxygen concentration.

Description

[Technical Field]

[0001] The present disclosure relates generally to binder fibers. More specifically, the present disclosure relates to polyolefin binder fibers used in nonwoven fabrics. [Background technology]

[0002] Nonwoven fibers tend to separate and destroy the fabric. This is especially true for nonwoven fabrics made with cellulose fibers. This problem has been overcome somewhat by adding additional fibers to the blend that bind the primary nonwoven fibers together. Polyolefins are commonly used as such binder fibers. Once the binder fibers are added, the mixture is heated to near the melting point of the binder fibers to heat-weld the binder fibers to the primary nonwoven fibers. However, due to the non-polar and / or non-reactive nature of the olefin fibers, bonding between the olefin and the cellulose fibers is poor. Furthermore, non-polar olefin fibers cannot wet polar cellulose fibers sufficiently to achieve good heat welding. Therefore, there is a need for spinnable binder fibers that are less susceptible to fiber breakage and have improved adhesion to cellulosic substrates. Summary of the Invention

[0003] Disclosed herein are bicomponent fibers comprising a first component and a second component. The first component comprises 70-97.5 wt. % polyethylene having a melt index, based on the weight of the first component, and 2.5-30 wt. % maleic anhydride-grafted polyethylene, based on the weight of the first component, the maleic anhydride-grafted polyethylene having a maleic anhydride level and melt index of 0.50-3.00 wt. % based on the weight of the maleic anhydride-grafted polyethylene. The ratio of the melt index of the polyethylene to the melt index of the maleic anhydride-grafted polyethylene is less than 1.25. The melt index is measured as described in the detailed description below.

[0004] Also disclosed herein is a nonwoven fabric comprising 30-70 wt. % bicomponent fibers according to embodiments disclosed herein and 30-70 wt. % cellulosic fibers, the weight percentages being based on the weight of the nonwoven fabric. DETAILED DESCRIPTION OF THE INVENTION

[0005] Aspects of the disclosed bicomponent fibers are described in more detail below. Biocomponent fibers can be used to form nonwovens, which can have a wide variety of uses, including, for example, wipes, face masks, tissues, bandages, and other medical and hygiene products. It should be noted, however, that this is merely an exemplary implementation of the embodiments disclosed herein. The embodiments are also applicable to other technologies prone to problems similar to those described above.

[0006] As used herein, the terms "comprising," "including," "having," and their derivatives are not intended to exclude the presence of any additional component, step, or procedure, whether specifically disclosed or not. For the avoidance of doubt, all compositions claimed through the use of the term "comprising" may include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless otherwise stated to the contrary. In contrast, the term "consisting essentially of" excludes from any subsequently recited scope any other component, step, or procedure, excepting those that are not essential to operability.

[0007] As used herein, the term "interpolymer" refers to a polymer prepared by the polymerization of at least two different types of monomers. Thus, the term interpolymer includes copolymers (used to refer to polymers prepared from two different types of monomers) and polymers prepared from three or more different types of monomers.

[0008] As used herein, the term "polymer" refers to a polymeric compound prepared by polymerizing monomers, whether of the same or different types. Thus, the generic term polymer encompasses the terms homopolymer (used to refer to a polymer prepared from only one type of monomer, with the understanding that trace amounts of impurities may be incorporated into the polymer structure) and interpolymer. Trace amounts of impurities (e.g., catalyst residues) may be incorporated into and / or present within the polymer. The polymer may be a single polymer or a polymer blend.

[0009] As used herein, the term "polyethylene" refers to a polymer containing greater than 50% by weight of units derived from ethylene monomers and, optionally, one or more comonomers. Polyethylene includes polyethylene homopolymers, copolymers, and interpolymers. Common forms of polyethylene compositions known in the art include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), ultra-low-density polyethylene (ULDPE), very low-density polyethylene (VLDPE), single-site catalyzed linear low-density polyethylene (m-LLDPE) containing both linear and substantially linear low-density resins, medium-density polyethylene (MDPE), and high-density polyethylene (HDPE). As used herein, a "propylene-based polymer" is a polymer that contains greater than 50 weight percent polymerized propylene monomer (based on the total amount of polymerizable monomers) and may optionally contain at least one comonomer. Propylene-based polymers include propylene homopolymers and propylene copolymers (meaning units derived from propylene and one or more comonomers). The terms "propylene-based polymer" and "polypropylene" may be used interchangeably.

[0010] As used herein, the terms "nonwoven," "nonwoven web," and "nonwoven fabric" are used interchangeably. "Nonwoven" refers to a web or fabric having a structure of individual fibers or threads interleaved randomly, rather than in a discernible manner as in knitted fabrics.

[0011] As used herein, the term "cellulose fiber" refers to a fiber made from ethers or esters of cellulose, which can be obtained from the bark, wood, or leaves of plants, or from other plant-based materials. In addition to cellulose, the fiber may also contain hemicellulose and lignin, and different proportions of these components affect the mechanical properties of the fiber. Natural cellulose fibers include, for example, cotton fiber, linen fiber, and wood pulp.

[0012] Manufactured cellulose fibers are derived from plants, which are processed into pulp and then extruded in the same way that synthetic fibers such as polyester or nylon are made. Rayon or viscose are among the most common "man-made" cellulose fibers and can be made from wood pulp.

[0013] Bicomponent Fiber The fibers taught herein can be formed by any conventional spinning technique. Bicomponent fibers can be formed, for example, via melt spinning. Melt spinning is one of the most common methods for producing polymer filaments. While several methods are available for filament production, melt spinning is the most economical approach due to the absence of solvents and the simplicity of the process. In melt spinning, polymer pellets or granules are fed into an extruder consisting of a screw for thermal melting, and the polymer melt is then forced through a spinneret under pressure. The extruded polymer is then quenched with cold air, solidifying the molten mass into filaments. Spun filaments lack adequate strength for industrial applications. Therefore, after melt spinning, the extruded filaments are typically mechanically stretched to align the molecular orientation along the filament axis, resulting in improved physical and mechanical properties. Mechanical stretching of the filaments consists of stretching the filaments by a number of times (from two times), which can be done directly after spinning or separately using the unstretched extruded polymer as the input material.

[0014] Nonwoven fabrics containing bicomponent binder fibers can be formed by any known technique.

[0015] The production of nonwoven fabrics typically involves two major processes: web formation and web consolidation. Examples of web-forming methods include carding, air laying, and wet laying.

[0016] Carding is a mechanical process that begins with baling fibers. These fibers are "opened," blended, and then transported by air conveyance to a card. They are then carded into a web by a carding machine, which is a rotating drum or series of drums covered with card wires (thin strips with teeth). The exact configuration of the card depends on the type and basis weight of the fibers being produced. The web can be parallel laid (in which case the majority of the fibers are laid in the machine direction) or random. A typical parallel laid carded web has good tensile strength, low elongation, and low tear strength in the machine direction, and vice versa in the cross direction. Machine parameters and fiber mixtures can be varied to produce a wide range of fabrics with different properties.

[0017] In the airlaid process, relatively short fibers are always fed by an air stream to a forming head. The forming head ensures that all fibers are homogeneously mixed. Again, air is used to force controlled portions of the fiber mixture away from the forming head and onto a moving belt, where it forms a randomly oriented web. Compared to carded webs, airlaid webs are less dense, more flexible, and lack stratified structures. Airlaid webs offer great versatility in terms of the fibers and fiber blends that can be used.

[0018] In the wet-laid process, a dilute slurry of water and fibers is deposited onto a moving wire screen. After most of the water is drained off, the fibers form a web. The web is further dewatered by pressing between rollers and drying. Binder impregnation is often included at a later stage in the process.

[0019] Thermal bonding uses the thermoplastic properties of certain synthetic fibers to form bonds under controlled heating. In some cases, the web fibers themselves can be used, but more often, low-melting or bicomponent fibers are introduced at the web formation stage to perform the bonding function later in the process. Several thermal bonding systems are in use. Calendaring uses heat and high pressure applied through rollers to weld fibrous webs together at high speeds. This is done in a carefully controlled stream of hot air.

[0020] Nonwoven fabrics can be produced that include 30-70% by weight of the disclosed bicomponent fibers, based on the weight of the nonwoven fabric, and 30-70% by weight of the cellulosic fibers, based on the weight of the nonwoven fabric. All individual values ​​and subranges are included and disclosed. For example, the nonwoven fabric can include 40-60% by weight of the disclosed bicomponent fibers, based on the weight of the nonwoven fabric, and 40-60% by weight of the cellulosic fibers, based on the weight of the nonwoven fabric.

[0021] The disclosed bicomponent binder fibers can include a first component and a second component. The first component can be a sheath component in a core / sheath structure. The first component can be a sea component in an islands-in-sea structure. The first component can be a first side component in a side-by-side structure. The first component can be a first pie segment component in a segmented pie structure.

[0022] The second component can be the core component in a core / sheath structure. The second component can be the island component in an islands-in-the-sea structure. The second component can be the second side component in a side-by-side structure. The second component can be the second pie segment component in a segmented pie structure. Additives may be added to the first and second components. Possible additives include, but are not limited to, antistatic agents, color enhancers, dyes, lubricants, fillers such as TiO2 or CaCO3, opacifiers, nucleating agents, processing aids, pigments, primary and / or secondary antioxidants, processing aids, UV stabilizers, antiblocking agents, slip agents, tackifiers, flame retardants, antibacterial agents, odor reducers, antifungal agents, and combinations thereof. The first or second component can contain 0.01, 0.1, 1-25, 1-20, 1-15, or 1-10 wt. % of such additives, based on the weight of the respective component.

[0023] The bicomponent fiber can comprise 10-90 weight percent of the first component, based on the weight of the bicomponent fiber. All individual values ​​and subranges are included and disclosed. For example, the bicomponent fiber can comprise 20-80 weight percent, or 30-70 weight percent, or 40-60 weight percent, or 45-55 weight percent of the first component, based on the weight of the bicomponent fiber. The bicomponent fiber can comprise 50 weight percent of the first component, based on the weight of the bicomponent fiber.

[0024] The bicomponent fiber can comprise 10-90 weight percent of the second component, based on the weight of the bicomponent fiber. All individual values ​​and subranges are included and disclosed. For example, the bicomponent fiber can comprise 20-80 weight percent, or 30-70 weight percent, or 40-60 weight percent, or 45-55 weight percent of the second component, based on the weight of the bicomponent fiber. The bicomponent fiber can comprise 50 weight percent of the second component, based on the weight of the bicomponent fiber.

[0025] First ingredient The first component can include polyethylene and maleic anhydride-grafted polyethylene. The first component can include 70 to 97.5 wt. % polyethylene, based on the total weight of the first component. All individual values ​​and subranges are included and disclosed. For example, the first component can include 85 to 95 wt. % polyethylene, based on the total weight of the first component. The first component can include 90 to 94 wt. % polyethylene, based on the total weight of the first component.

[0026] The polyethylene in the first component is 0.920 to 0.975 g / cm 3 The density is measured according to ASTM D792, Method B. All individual values ​​and subranges are included and disclosed. For example, the polyethylene in the first component can have a density of 0.920, 0.930, 0.940, 0.950, 0.960, 0.970 g / cm. 3 From the lower limit of 0.975, 0.970, 0.960, 0.950, 0.940, 0.930 g / cm 3 The density can be up to an upper limit of .

[0027] The polyethylene in the first component can have a melt index of 10 to 50 g / 10 min, the melt index being measured as described below. All individual values ​​and subranges are disclosed and included. For example, the polyethylene in the first component can have a melt index of 20 to 40 g / 10 min, the melt index being measured as described below. The melt index of the maleic anhydride-grafted polyethylene in the first component can be greater than 25 g / 10 min.

[0028] The polyethylene in the first component has a ratio of weight average molecular weight to number average molecular weight (M) as measured by GPC (gel permeation chromatography) of 2.0 to 6.0. w / M n), all individual values ​​and subranges are included. The polyethylene in the first component may have a ratio of weight average molecular weight to number average molecular weight (M), as measured by GPC, from a lower limit of 2.0, 2.5, 3.5, 4.0, 4.5, 5.0, or 5.5 to an upper limit of 6.0, 5.5, 5.0, 4.5, 4.0, 3.5, 3.0, or 2.5. w / M n )

[0029] The first component can comprise 2.5 to 30 weight percent maleic anhydride-grafted polyethylene, based on the total weight of the first component. All individual values ​​and subranges are included and disclosed. For example, the first component can comprise 5 to 15 weight percent maleic anhydride-grafted polyethylene, based on the weight of the first component. The first component can comprise 6 to 10 weight percent maleic anhydride-grafted polyethylene, based on the weight of the first component.

[0030] The maleic anhydride-grafted polyethylene in the first component can have a maleic anhydride level of 0.5 to 3.0 wt %, based on the weight of the maleic anhydride-grafted polyethylene. All individual values ​​and subranges are included and disclosed. For example, the maleic anhydride-grafted polyethylene in the first component can have a maleic anhydride level of 0.9 to 1.7 wt %, based on the weight of the maleic anhydride-grafted polyethylene. The maleic anhydride-grafted polyethylene in the first component can have a maleic anhydride level of 1 to 1.5 wt %, based on the weight of the maleic anhydride-grafted polyethylene.

[0031] The maleic anhydride-grafted polyethylene in the first component can have a melt index greater than 25 g / 10 minutes, where the melt index is measured as described below. The maleic anhydride-grafted polyethylene in the first component can have a melt index of 25 to 1000 g / 10 minutes, where the melt index is measured as described below. All individual values ​​and subranges are included. For example, the maleic anhydride-grafted polyethylene in the first component can have a melt index from a lower limit of 25, 100, 200, 300, 400, 500, 600, 700, 800, or 900 g / 10 minutes (where the melt index is measured as described below) to an upper limit of 900, 800, 700, 600, 500, 400, 300, 200, 100, or 35 g / 10 minutes (where the melt index is measured as described below).

[0032] The maleic anhydride grafted polyethylene in the first component has a weight average molecular weight to number average molecular weight ratio (M) as measured by GPC of 2.0 to 6.0. w / M n ), all individual values ​​and subranges are included. The maleic anhydride-grafted polyethylene in the first component may have a ratio of weight average molecular weight to number average molecular weight (M), as measured by GPC, from a lower limit of 2.0, 2.5, 3.5, 4.0, 4.5, 5.0, or 5.5 to an upper limit of 6.0, 5.5, 5.0, 4.5, 4.0, 3.5, 3.0, or 2.5. w / M n )

[0033] The ratio of the melt index of the polyethylene to the melt index of the maleic anhydride-grafted polyethylene may be less than 1.25. The ratio of the melt index of the polyethylene to the melt index of the maleic anhydride-grafted polyethylene may be from 0.025 to less than 1.25, with the melt index being measured as described below. All individual values ​​and subranges are included. For example, the ratio of the melt index of the polyethylene to the melt index of the maleic anhydride-grafted polyethylene may be from 0.05 to 1.00. The ratio of the melt index of the polyethylene to the melt index of the maleic anhydride-grafted polyethylene may be from 0.025 to 0.10. The ratio of the melt index of the polyethylene to the melt index of the maleic anhydride-grafted polyethylene may be from 0.90 to 1.10.

[0034] Maleic anhydride grafted polyethylene is 0.865 to 0.965 g / cm 3 All individual values ​​and subranges are included. For example, maleic anhydride grafted polyethylene can have a density of 0.865, 0.875, 0.885, 0.895, 0.905, 0.915, 0.925, 0.935, 0.945, or 0.955 g / cm. 3 from the lower limit of 0.965, 0.955, 0.945, 0.935, 0.925, 0.915, 0.905, 0.895, 0.885, or 0.875 g / cm 3 The density can be up to an upper limit of .

[0035] Second component The second component can include polypropylene, polyethylene, or polyester. The second component of the bicomponent binder fiber can include polypropylene. The second component of the bicomponent binder fiber can include polyethylene. The second component of the bicomponent binder fiber can include polyester.

[0036] When polypropylene or polyester is used for the second component, any conventional process for producing polypropylene or polyester can be used, including those described in U.S. Patent Nos. 5,093,415 and 5,548,042.

[0037] Any conventional polymerization process can be used to produce the polymer for the second component or the first component. Such conventional polymerization processes for polyethylene include, but are not limited to, solution polymerization processes using one or more conventional reactors, such as loop reactors, isothermal reactors, stirred tank reactors, parallel or series batch reactors, and / or any combination thereof. Such conventional polymerization processes also include gas phase, solution, or slurry polymerization, or any combination thereof, using any type of reactor or reactor configuration known in the art.

[0038] Generally, solution-phase polymerization processes occur in one or more well-mixed reactors, such as one or more isothermal loop reactors or one or more adiabatic reactors, at temperatures ranging from 115 to 250°C, e.g., 115 to 200°C, and pressures ranging from 300 to 1000 psi, e.g., 400 to 750 psi. In one example, the temperature of the first reactor in a dual reactor system is 115 to 190°C, e.g., 115 to 150°C, and the temperature of the second reactor is 150 to 200°C, e.g., 170 to 195°C. In another example, the reactor temperature in a single reactor system is 115 to 190°C, e.g., 115 to 150°C. Residence times in solution-phase polymerization processes can typically be in the range of 2 to 30 minutes, e.g., 10 to 20 minutes. Ethylene, solvent, hydrogen, one or more catalyst systems, optionally one or more cocatalysts, and optionally one or more comonomers are continuously fed to one or more reactors. Exemplary solvents include, but are not limited to, isoparaffins. For example, such solvents are commercially available from ExxonMobil Chemical Co. (Houston, Texas) under the name ISOPAR E. The resulting polymer and solvent mixture is then removed from the reactor, and the polymer composition is isolated. The solvent is typically recovered through a solvent recovery unit, i.e., a heat exchanger and a gas-liquid separator drum, and then recycled to the polymerization system.

[0039] The polymer composition can be produced via solution polymerization in a dual reactor system, for example, a dual loop reactor system, where ethylene and optionally one or more α-olefins are polymerized in the presence of one or more catalyst systems. Additionally, one or more cocatalysts may be present.

[0040] The polymer composition can be produced through solution polymerization in a single reactor system, for example, a single loop reactor system, where ethylene and optionally one or more α-olefins are polymerized in the presence of one or more catalyst systems. Two different catalysts can be used in a dual reactor system. One or both of the two different catalysts can have the formula (I) shown below. This allows the production of the bimodal interpolymer composition described above.

[0041] An exemplary catalyst system suitable for producing a polymer can be a catalyst system comprising a precursor catalyst component comprising a metal-ligand complex of formula (I).

[0042] [ka]

[0043] In formula (I), M is a metal selected from titanium, zirconium, or hafnium, the metal being in a +2, +3, or +4 formal oxidation state; n is 0, 1, or 2; when n is 1, X is a monodentate or bidentate ligand; when n is 2, each X is a monodentate ligand and is the same or different; the metal-ligand complex is overall charge neutral; and each Z is independently —O—, —S—, —N(R N )-, or -P(R P )-, and L is selected from (C1 to C 40 ) hydrocarbylene or (C1-C 40 ) heterohydrocarbylene, and independently each R N and R P is (C1~C 30 ) hydrocarbyl or (C1-C 30 ) heterohydrocarbyl, (C1-C 40 The hydrocarbylene has a linker skeleton of 1 to 10 carbon atoms that connects the two Z groups in formula (I) to which L is attached, or 40 ) Heterohydrocarbylene has a moiety containing a linker skeleton of 1 atom to 10 atoms connecting the two Z groups in formula (I), and (C1-C40 Each of the 1 to 10 atoms of the 1 to 10 atom linker backbone of the heterohydrocarbylene is independently a carbon atom or a heteroatom, and each heteroatom is independently O, S, S(O), S(O), Si(R C )2, Ge(R C )2, P(R C ), or N(R C ) and independently, each R C is (C1~C 30 ) hydrocarbyl or (C1-C 30 ) heterohydrocarbyl, and R 1 and R 8 are independently -H, (C1~C 40 ) hydrocarbyl, (C1-C 40 ) heterohydrocarbyl, -Si(R C )3, -Ge(R C )3, -P(R P )2, -N(R N )2, -OR C , -SR C , -NO2, -CN, -CF3, R C S(O)-, R C S(O)2-, (R C )2C=N-, R C C(O)O-, R C OC(O)-, R C C(O)N(R N )-, (R N )2NC(O)-, halogen, and a radical having formula (II), formula (III), or formula (IV).

[0044] [ka]

[0045] In formulas (II), (III), and (IV), R 31~35 , R 41~48 , or R 51~59 Each of (C1 to C 40 ) hydrocarbyl, (C1-C 40 ) heterohydrocarbyl, -Si(R C )3, -Ge(RC )3, -P(R P )2, -N(R N )2, -N=CHR C , -OR C , -SR C , -NO2, -CN, -CF3, R C S(O)-, R C S(O)2-, (R C )2C=N-, R C C(O)O-, R C OC(O)-, R C C(O)N(R N )-, (R N )2NC(O)—, halogen, or —H, with the proviso that R 1 or R 8 is a radical having formula (II), formula (III), or formula (IV), wherein R C、 R N , and R P is as defined above.

[0046] In formula (I), R 2~4 , R 5~7 , or R 9~16 Each of (C1 to C 40 ) hydrocarbyl, (C1-C 40 ) heterohydrocarbyl, -Si(R C )3, -Ge(R C )3, -P(R P )2, -N(R N )2, -N=CHR C , -OR C , -SR C , -NO2, -CN, -CF3, R C S(O)-, R C S(O)2-, (R C )2C=N-, R C C(O)O-, R C OC(O)-, R C C(O)N(R N )-, (R C )2NC(O)—, halogen, and —H, wherein R C , R N , and R Pis as defined above.

[0047] A catalyst system comprising a metal-ligand complex of formula (I) can be made catalytically active by any technique known in the art for activating metal-based catalysts for polymerization reactions. For example, a metal-ligand complex of formula (I) can be made catalytically active by contacting the complex with or combining the complex with an activating cocatalyst. Activating cocatalysts suitable for use herein include alkylaluminums, polymeric or oligomeric alumoxanes (also known as aluminoxanes), neutral Lewis acids, and non-polymeric, non-coordinating, ion-forming compounds (including the use of such compounds under oxidizing conditions). A suitable activation technique is bulk electrolysis. Combinations of one or more of the foregoing activating cocatalysts and techniques are also contemplated. The term "alkylaluminum" refers to monoalkylaluminum dihydrides or dihalides, dialkylaluminum hydrides or halides, or trialkylaluminums. Examples of polymeric or oligomeric alumoxanes include methylalumoxane, triisobutylaluminum-modified methylalumoxane, and isobutylalumoxane.

[0048] The Lewis acid activator (co-catalyst) may be, as described herein, a compound having 1 to 3 (C1 to C 20 Examples of Group 13 metal compounds include tri((C-C) hydrocarbyl substituents. 20 )hydrocarbyl)-substituted aluminum compounds, or tri((C1-C 20 )hydrocarbyl)-boron compounds. Additional examples of Group 13 metal compounds include tri(hydrocarbyl)-substituted aluminum, tri((C1-C 20 )hydrocarbyl)-boron compounds, tri((C1-C 10 ) alkyl) aluminum, tri((C6-C 18)aryl)boron compounds and their halogenated (including perhalogenated) derivatives. Other examples of Group 13 metal compounds are tris(fluoro-substituted phenyl)borane, tris(pentafluorophenyl)borane. Activating cocatalysts include tris((C1-C 20 )hydrocarbyl)borates (e.g., trityl tetrafluoroborate) or tri((C 1~ C 20 )hydrocarbyl)ammonium tetra((C1-C 20 As used herein, the term "ammonium" refers to a ((C1-C2) ammonium tetrakis(pentafluorophenyl)borane, such as bis(octadecyl)methylammonium tetrakis(pentafluorophenyl)borane. 20 ) Hydrocarbyl) 4N + , ((C1~C 20 )hydrocarbyl)3N(H) + , ((C1~C 20 )hydrocarbyl)2N(H)2 + , (C1~C 20 ) Hydrocarbyl N(H)3 + , or N(H)4 + Each of the nitrogen cations (C1 to C 20 When two or more hydrocarbyls are present, they may be the same or different.

[0049] As a combination of neutral Lewis acid activators (cocatalysts), tri((C1-C4) alkyl)aluminum and tri((C6-C 18(aryl)boron compounds, especially tris(pentafluorophenyl)borane. Other examples include mixtures containing such neutral Lewis acid mixtures in combination with polymeric or oligomeric alumoxanes, and combinations of a single neutral Lewis acid, especially tris(pentafluorophenyl)borane, with polymeric or oligomeric alumoxanes. The molar ratio of (metal-ligand complex):(tris(pentafluorophenyl)borane):(alumoxane) [e.g., Group 4 metal-ligand complex):(tris(pentafluorophenyl)borane):(alumoxane)] can be 1:1:1 to 1:10:30, or 1:1:1.5 to 1:5:10.

[0050] Catalyst systems comprising the metal-ligand complexes of formula (I) can be activated to form active catalyst compositions by combining them with one or more cocatalysts, such as cation-forming cocatalysts, strong Lewis acids, or combinations thereof. Suitable activating cocatalysts include polymeric or oligomeric aluminoxanes, particularly methylaluminoxane, as well as inert, compatible, non-coordinating, ion-forming compounds. Examples of suitable cocatalysts include modified methylaluminoxane (MMAO), bis(hydrogenated tallow alkyl)methyl, tetrakis(pentafluorophenyl)borate (1 - ) amines, and combinations thereof.

[0051] One or more of the foregoing activating cocatalysts may be used in combination with one another. Preferred combinations are mixtures of tri((C1-C4)hydrocarbyl)aluminum, tri((C1-C4)hydrocarbyl)borane, or ammonium borate with an oligomeric or polymeric alumoxane compound. The ratio of the total number of moles of the one or more metal-ligand complexes of formula (I) to the total number of moles of the one or more activating cocatalysts is from 1:10,000 to 100:1. The ratio can be at least 1:5000, or at least 1:1000, and can be 10:1 or less, or 1:1 or less. When alumoxane is used alone as the activating cocatalyst, the number of moles of alumoxane used can be at least 100 times the number of moles of the metal-ligand complex of formula (I). When tris(pentafluorophenyl)borane is used alone as the activating cocatalyst, the number of moles of tris(pentafluorophenyl)borane to the total number of moles of the one or more metal-ligand complexes of Formula (I) that can be used ranges from 0.5:1 to 10:1, 1:1 to 6:1, or 1:1 to 5:1. The remaining activating cocatalysts are generally used in a molar amount approximately equal to the total molar amount of the one or more metal-ligand complexes of Formula (I).

[0052] Preparation of MAH-grafted polyethylene The MAH-grafted polyethylene can be produced post-reactor using an extruder, which can be a multi-screw extruder equipped with positive and negative conveying screw elements and lobed kneading / mixing plates, paddles, or blocks.

[0053] Generally, positive-conveying screw elements convey the ethylene-based polymer and / or functionalizing agent away from the first zone of the extruder (where the ethylene-based polymer, functionalizing agent, and initiator are initially received and mixed) toward the later zones of the extruder (where the ethylene-based polymer is liquefied and discharged from the extruder). Negative-conveying screw elements attempt to direct flow away from the last zone toward the first zone. Essentially, any multi-screw extruder containing screw elements with means similar to those described can be used. It is contemplated that such screws may counter-rotate with respect to one another. See, for example, M. Xanthos, Reactive Extrusion: Principles and Practice, Hanser Publishers, January 1, 1992, Technology & Engineering. Co-rotating twin-screw extruders can be used. The extruder can have an L / D ratio of 36 to 60. All individual values ​​and subranges are included and disclosed. For example, the extruder can have an L / D ratio of 44 to 60, 44 to 50, or 50 to 60. Twin screw extruders can be used in series to achieve an effective L / D ratio of 80 to 90. The extruders can have a diameter (D) of 30 to 200 mm.

[0054] The extruder can be operated at a production rate sufficient to produce 2,000 pounds or more per hour of grafted ethylene-based polymer, or 2,100 pounds or more per hour of grafted ethylene-based polymer, or 2,200 pounds or more per hour of grafted ethylene-based polymer. One skilled in the art can convert this high speed to suit different size extruders. Without being bound by any particular theory, it is believed that the rates (Q1, Q2) for extruders of different diameters (D1, D2) are (Q1 / Q2)=(D1 / D2) n The exponent n is a scale-up factor, typically 2-3.

[0055] The screw speed can be between 200 rpm and 900 rpm. The screw speed is adjusted based on the torque generated and the melt temperature. The barrel temperature in the reaction zone of the extruder can be between 160°C and 250°C. At the entrance to the extruder, the temperature is kept low (e.g., below 150°C) to avoid premature melting. Towards the end of the extruder, the temperature may be reduced to cool the melt.

[0056] The step of reacting the ethylene-based polymer composition with at least one functionalizing agent and at least one free-radical initiator can be carried out at a melt temperature of 200° C. or greater, or 210° C. or greater, or 220° C. or greater, or 230° C. or greater, or 240° C. or greater, or 250° C. or greater. The melt temperature is the temperature of the molten extrudate measured after the extruder screw and before the die. This temperature is typically measured with a thermocouple.

[0057] The step of reacting the ethylene-based polymer composition with at least one functionalizing agent and at least one free-radical initiator can be carried out at a melt temperature of 350°C or less, or 340°C or less, or 330°C or less, or 320°C or less, or 310°C or less, or 300°C or less.

[0058] The step of reacting the ethylene-based polymer composition with at least one functionalizing agent and at least one free-radical initiator can be conducted at a melt temperature of 200°C or greater, or 210°C or greater, or 220°C or greater, or 230°C or greater, or 240°C or greater, or 250°C or greater, to 350°C or less, or 340°C or less, or 330°C or less, or 320°C or less, or 310°C or less, or 300°C or less.

[0059] Test Method Melt Viscosity The melt viscosity of Inventive Example 2 is measured according to ASTM D 3236 (177°C, 350°F) using a Brookfield digital viscometer (Model DV-III, Version 3) and a disposable aluminum sample chamber. The spindle used is typically an SC-31 hot melt spindle, suitable for measuring viscosities in the range of 10 to 100,000 centipoise. The sample is poured into the chamber, which is then inserted into a Brookfield Thermosel and secured in place. The sample chamber has a notch in the bottom that fits the bottom of the Brookfield Thermosel to ensure the chamber does not rotate when the spindle is inserted and spinning. The sample (approximately 8 to 10 grams of polymer or resin) is heated to the required temperature until the molten sample is approximately 1 inch below the top of the sample chamber. The viscometer device is lowered, submerging the spindle into the sample chamber. The lowering continues until the viscometer bracket is aligned with the Thermosel. Turn on the viscometer and set it to operate at a shear rate that results in a torque reading within 40-60 percent of the total torque capacity, based on the rpm output of the viscometer. Take readings every minute for approximately 15 minutes, or until the value stabilizes, at which point record the final reading.

[0060] Melt Index Melt index for samples other than Affinity™ GA 1000R polyolefin elastomer is measured according to ASTM D-1238, condition 190°C / 2.16 kg. For polymers having a melt index of 200 g / 10 min or greater, melt index is calculated as described in U.S. Patent Nos. 6,335,410, 6,054,544, and 6,723,810 using the following formula:

[0061]

number

[0062] density Samples for density measurements are prepared according to ASTM D1928. The polymer sample is pressed for 3 minutes at 190°C and 30,000 psi (207 MPa), then for 1 minute at 21°C and 30,000 psi (207 MPa). Measurements are made within 1 hour of pressing the sample using ASTM D792, Method B.

[0063] Fourier Transform Infrared Spectroscopy (FTIR) Analysis - Maleic Anhydride Content The concentration of maleic anhydride is 1791 cm -1 It is calculated by the ratio of the maleic anhydride peak height to the polymer reference peak at wavenumber 2019 cm for polyethylene. -1 The maleic anhydride content is calculated by multiplying this ratio by the appropriate calibration constant. The equation used for maleic acid grafted olefin-based polymers (with a polyethylene base peak) has the following form, as shown in Equation 2:

[0064]

number

[0065] The calibration constant A can be determined using a C NMR standard or by using titration. The actual calibration constant may vary slightly depending on the instrument and polymer. Wavenumber 1712 cm -1The second component in is primarily responsible for the presence of maleic acid, which is negligible for freshly grafted material. However, over time, maleic anhydride is readily converted to maleic acid in the presence of moisture. Depending on the surface area, significant hydrolysis can occur in just a few days under ambient conditions. The acid is expressed at a wavenumber of 1712 cm. -1 The constant B in Equation 1 is a correction for the difference in extinction coefficients between the anhydride and acid groups.

[0066] The sample preparation procedure begins by pressing the sample between two protective films in a heated press at 150–180°C for 1 hour to a thickness typically between 0.05–0.15 mm. MYLAR and TEFLON are suitable protective films to protect the sample from the platen. Aluminum foil should never be used (maleic anhydride reacts with aluminum). The platen must be under pressure (10 tons) for approximately 5 minutes. The sample is allowed to cool to room temperature, placed in an appropriate sample holder, and then scanned by FTIR. A background scan should be performed before each sample scan or as needed. Test precision is good, with an inherent variation of less than ±5%. Samples should be stored with a desiccant to prevent excessive hydrolysis. Moisture content in the product has been measured to as high as 0.1 weight percent. However, the conversion from anhydride to acid is reversible with temperature, and complete conversion can take up to a week. The conversion is best done in a vacuum oven at 150°C and requires a good vacuum (greater than 27 inches Hg). If the vacuum is insufficient, the sample will tend to oxidize and will react at approximately 1740 cm -1 The infrared peaks at about 1791 and 1712 cm give values ​​that are too low for the grafting level. -1 is represented by a peak at

[0067] Surface oxygen concentration Surface oxygen concentration is measured by X-ray photoelectron spectroscopy (XPS). XPS is a surface-sensitive quantitative spectroscopic technique that provides elemental and oxidation state information from the first 5-10 nm of the surface. XPS spectra are obtained by irradiating a material with X-rays while simultaneously measuring the kinetic energy and current of photoelectrons escaping from the top 2-10 nm. Every element has a unique kinetic energy, and the elemental peak area is used to determine the surface composition. XPS is sensitive to all elements except hydrogen and helium. The resulting surface composition is taken to be 100%.

[0068] Data are acquired on a Thermo K-alpha XPS spectrometer using Al K-alpha X-rays operating at 72 W (12 kV, 6 mA) with a 400 μm analysis area. XPS spectra are collected using 80 eV pass energy, 0.1 eV / step, 50 ms dwell time, and a minimum of five sweeps. Data are collected from five locations on each sample. Surface element concentrations are determined using Thermo Advantage V5.9922 Build 06667 software. Oxygen concentrations are corrected for any formulation or processing additives.

[0069] Gel Permeation Chromatography (Conventional GPC) The chromatography system consisted of a PolymerChar GPC-IR (Valencia, Spain) high-temperature GPC chromatograph equipped with a built-in IR5 infrared detector (IR5). The autosampler oven compartment was set to 160 °C, and the column compartment was set to 150 °C. The columns used were four Agilent "Mixed A" 30 cm, 20 micron linear mixed-bed columns. The chromatographic solvent used was 1,2,4 trichlorobenzene containing 200 ppm butylated hydroxytoluene (BHT). The solvent source was nitrogen sparged. The injection volume used was 200 microliters, and the flow rate was 1.0 milliliters / minute.

[0070] Calibration of the GPC column set is performed using at least 20 narrow molecular weight distribution polystyrene standards with molecular weights ranging from 580 to 8,400,000 g / mol, arranged in six "cocktail" mixtures with at least 10 intervals between individual molecular weights. Standards are purchased from Agilent Technologies. Polystyrene standards are prepared at 0.025 grams in 50 milliliters of solvent for molecular weights equal to or greater than 1,000,000 g / mol, and 0.05 grams in 50 milliliters of solvent for molecular weights less than 1,000,000 g / mol. The polystyrene standards are dissolved with gentle stirring at 80°C for 30 minutes. The polystyrene standard peak molecular weights are converted to ethylene / alpha-olefin interpolymer molecular weights using the following equation (as described in Williams and Ward, J. Polym. Sci., Polym. Let., 6, 621 (1968)): M ポリエチレン =A×(M ポリスチレン ) B (Formula 3) where M is the molecular weight, A has a value of 0.4315, and B is equal to 1.0.

[0071] A fifth-order polynomial is used to fit each ethylene / alpha-olefin interpolymer equivalent calibration point, such as that obtained for the NIST standard NBS1475 at a molecular weight of 52,000 g / mol. A small adjustment to A (approximately 0.39-0.44) is made to correct for column resolution and band-broadening effects.

[0072] A total plate count for the GPC column set is performed using eicosane (prepared at 0.04 g in 50 milliliters of TCB and dissolved for 20 minutes with gentle agitation). Plate count (Equation 4) and symmetry (Equation 5) are measured with a 200 microliter injection according to the following equations:

[0073]

number

[0074]

number

[0075] Samples were prepared semi-automatically using PolymerChar "Instrument Control" software, with a target sample weight of 2 mg / mL, and the solvent (containing 200 ppm BHT) was added via a PolymerChar high-temperature autosampler to a pre-nitrogen-flushed septa-capped vial. The sample was dissolved at 160°C under "slow" shaking for 3 hours.

[0076] M n , M w , and M z The calculation of is performed using PolymerChar GPCOne™ software, at each equally spaced data collection point i(IR i ) baseline-subtracted IR chromatogram and the ethylene / alpha-olefin interpolymer equivalent molecular weight (M in g / mol) obtained from a narrow standard calibration curve for point i from Equation 3 ポリエチレン、i) based on the GPC results using the built-in IR5 detector (measurement channel) of the PolymerChar GPC-IR chromatograph according to Equations 7a-c. Subsequently, a GPC molecular weight distribution plot (wt(lgMW) vs. lgMW plot, where wt(lgMW) is the weight fraction of molecules with a molecular weight of lgMW) can be obtained. The molecular weight (MW) is in g / mol, and wt(lgMW) follows Equation 6.

[0077]

number

[0078]

number

[0079] To monitor deviations over time, a flow rate marker (decane) is introduced into each sample via a micropump controlled by the PolymerChar GPC-IR system. This flow rate marker (FM) is used to linearly correct the pump flow rate (Flow Rate (Nominal)) for each sample by aligning the RV of each decane peak in the sample (RV (FM Sample)) with the RV of the decane peak in the narrow standard calibration (RV (FM Calibration)). Any change in time of the decane marker peak is then assumed to be related to a linear shift in flow rate (Flow Rate (Effective)) throughout the experiment. To facilitate the highest accuracy in measuring the RV of the flow rate marker peaks, a least-squares fitting routine is used to fit the peaks in the flow rate marker concentration chromatogram to a quadratic equation. The first derivative of the quadratic equation is then used to solve for the true peak position. After calibrating the system based on the flow rate marker peaks, the effective flow rate (with respect to the narrow standard calibration) is calculated as follows: Equation 8. Processing of the flow rate marker peaks is performed via PolymerChar GPCOne™ software. Correct the allowable flow rate so that the effective flow rate is within 0.5% of the nominal flow rate. flow rate 実効 = flow rate 公称 ×(RV(FM 較正 ) / RV(FM 試料 )) (Equation 8) [Example]

[0080] The polyethylene and maleic anhydride grafted polyethylene materials used are listed in Table 1. All commercial resins are available from The Dow Chemical Company.

[0081] [Table 1] * Calculated from melt viscosity as described in the Test Methods section above.

[0082] The functionalization reactions to produce experimental MAH-grafted polyethylenes 1 and 2 are carried out in a 92 mm co-rotating twin-screw extruder. The extruder is configured with 11 barrels (44 L / D). The extruder is equipped with a "weight loss feeder," and peroxide and MAH are metered into the extruder at barrel 3. A standard extruder temperature profile is used for all experiments, with barrel temperatures 2-8 ranging from 170-225°C. Barrels 9-11 use low temperatures to cool the resin for pelletization. Barrel 1 is cooled to prevent premature melting. All grafted polymer compositions are pelletized in water. An inert atmosphere is injected into the extruder to minimize oxidation. A vacuum (20" Hg) is applied to remove residues prior to pelletization. The melt temperature is above 200°C. A speed of 2000 lbs / hr and a screw speed of 575-625 rpm are used.

[0083] A free radical initiator (POX) is used: 2,5-dimethyl-2,5-di(t-butylperoxy)hexane (DBPH, CAS No. 78-63-7) available from Arkema or Akzo Nobel Corp., diluted with 350 SUS white mineral oil. The formulation consists of a base polymer (e.g., high-density polyethylene), MAH (maleic anhydride), and peroxide diluted (1:1) with mineral oil for ease of handling and delivery. The peroxide level is 500-700 ppm, and the MAH level is 1.3-1.9 wt%. For experimental MAH-grafted polyethylenes 1 and 2, DMDA-8965 NT 7 high-density polyethylene resin is used as the base polymer.

[0084] Bicomponent fibers with a core-sheath structure are spun on a Hills Bicomponent Continuous Filament Fiber Spinning Line at a throughput rate of 0.6 (grams / hole / minute). A Hills Bicomponent die operating at a core / sheath ratio of 50% by weight / 50% by weight is used. Comparative examples ("CE") 2-5 and inventive examples ("IE") 1-2 are spun from 100% by weight polypropylene (0.900 g / cm3 measured according to ASTM D792 Method B). 3 A polyethylene (ExxonMobil PP3155E5 manufactured by ExxonMobil, having a density of 1000 kJ / 1000 kcal / ...

[0085] The die configuration consisted of 144 holes with a hole diameter of 0.6 mm. The hole L / D ratio was 4 / 1. The quench air temperature was set at 18°C, and the quench air flow rate was set at 50% of its maximum flow rate. The extruder profile was adjusted to achieve a melt temperature of 230°C for both the core and sheath materials. The 144-filament yarn was drawn using an air aspirator. The fiber was drawn using a slot pressure of 40 psi, and the resulting fiber diameter was approximately 20 microns. The fibers were collected and wrapped in aluminum foil to avoid contamination. The results of the surface oxygen concentration test described in the Test Methods section above for both the inventive and comparative examples are listed in Table 2 below. As in Table 1, all commercially available resins were obtained from The Dow Chemical Company unless otherwise indicated.

[0086] [Table 2]

[0087] As can be seen from Table 2, the inventive examples have higher surface oxygen concentrations than the comparative examples, despite the lower MAH content. The higher surface oxygen concentrations indicate the presence of more maleic anhydride on the fiber surface of the inventive samples. A higher concentration of maleic anhydride on the fiber surface can promote the reactivity of hydroxyl groups on cellulose fibers, resulting in nonwoven fabrics with improved bonding efficiency and better mechanical strength.

Claims

1. A bicomponent fiber, a. a first component, i. 70 to 97.5 wt. %, based on the weight of the first component, of a polyethylene having a melt index; and ii. 2.5 to 30 wt % maleic anhydride grafted polyethylene, based on the weight of the first component, wherein the maleic anhydride grafted polyethylene has a maleic anhydride level of 0.50 to 3.00 wt %, based on the weight of the maleic anhydride grafted polyethylene, and a melt index. , including a first component, wherein the ratio of the melt index of the polyethylene to the melt index of the maleic anhydride-grafted polyethylene is less than 1.25; b. a second component; A bicomponent fiber comprising:

2. 10. The bicomponent fiber of claim 1, wherein the first component is a sheath component and the second component is a core component.

3. 3. The biocomponent fiber of claim 1, comprising 10 to 90 weight percent of the first component and 90 to 10 weight percent of the second component, based on the weight of the bicomponent fiber.

4. The bicomponent fiber of any of claims 1 to 3, wherein the second component comprises polypropylene, polyethylene, or polyester.

5. 5. The bicomponent fiber of claim 1, wherein the ratio of the melt index of the polyethylene to the melt index of the maleic anhydride grafted polyethylene is from 0.025 to less than 1.

25.

6. The polyethylene in the first component has a density of 0.920 to 0.975 g / cm ３ and the melt index of the polyethylene in the first component is 10 to 50 g / 10 min.

7. The maleic anhydride grafted polyethylene in the first component has a melt index of greater than 25 g / 10 min, and the maleic anhydride grafted polyethylene has a melt index of 0.856 to 0.965 g / cm ３ The bicomponent fiber of any one of claims 1 to 6, having a density of

8. A nonwoven fabric, a. 30 to 70 weight percent of the biocomponent fiber of any one of claims 1 to 7, based on the weight of the nonwoven fabric; b. 30 to 70 weight percent cellulose fibers, based on the total weight of the nonwoven fabric; Nonwoven fabrics, including:

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