Absorbent article

Abstract

The present disclosure provides an article of manufacture. In one embodiment, the article includes (1) a nonwoven meltblown web. The fibers have an average fiber diameter of 1 [mu] m to 15 [mu] m. The fibers comprise (A) an ethylene / alpha-olefin copolymer having (i) a density of from 0.920 g / cc to 0.940 g / cc, and (ii) a melt index of from 50 g / 10 min to 250 g / 10 min. The fibers comprise (B) two or more surfactants, each surfactant having an HLB value of from 0.5 to 10.0. The article also includes (2) a plurality of superabsorbent polymer particles (SAPs) dispersed in the web.

Description

Background Technology

[0001] The absorbent core structure of hygiene products (such as cleaning products, hygiene products (diapers, feminine hygiene products), wipes, water-retaining agents, dehydrating agents, sludge coagulants, disposable towels, thickeners, anti-caking agents, wound care products, and release control agents for various chemicals and pharmaceuticals) requires high liquid absorbency. Fluff pulp and superabsorbent polymers (SAPs) are known absorbent materials. Absorbent core structures composed of fluff pulp and / or SAPs enable the product to absorb large amounts of fluids (e.g., water, urine, and / or blood) during use. However, fluff pulp can be fluffy and thick, limiting its use in products such as feminine liner, where thin and lightweight constructions are preferred. Horizontal liquid diffusion rate is another key factor, typically achieved using an acquisition and distribution layer (ADL) made of polyethylene terephthalate (PET). The recyclability of PET-containing hygiene products is limited due to the incompatibility of PET with polypropylene or polyethylene.

[0002] Therefore, there is a need for a liquid absorbent product with good absorption properties that is PET-free. There is also a need for a liquid absorbent product made of a recyclable ethylene-based polymer. Summary of the Invention

[0003] This disclosure provides an article of manufacture. In one embodiment, the article of manufacture comprises (1) a nonwoven meltblown fiber web. The fibers have an average fiber diameter of 1 micrometer to 15 micrometers. The fibers comprise (A) an ethylene / α-olefin copolymer having (i) a density of 0.920 g / cc to 0.940 g / cc and (ii) a melt index of 50 g / 10 min to 250 g / 10 min. The fibers comprise (B) two or more surfactants, each surfactant having an HLB value of 0.5 to 10.0. The article of manufacture also comprises (2) a plurality of superabsorbent polymer particles (SAP) dispersed in the web. Attached Figure Description

[0004] Figure 1 This is a schematic representation of a liquid absorption test.

[0005] Figure 2 This is a schematic representation of the production of nonwoven fiber webs.

[0006] definition

[0007] Any reference to the periodic table is as in the version published by CRC Press, Inc. in 1990–1991. A group of elements in the table is referred to using a new notation for numbering the groups.

[0008] For the purposes of U.S. patent practice, any reference to a patent, patent application, or publication is incorporated herein by reference in its entirety (or its equivalent U.S. version thereof), especially the disclosure relating to definitions in the art (where there is no inconsistency with any definitions specifically provided in this disclosure) and common sense.

[0009] The numerical ranges disclosed herein include all values ​​from the lower limit to the upper limit, and include both the lower limit and the upper limit. For a range containing exact values ​​(e.g., a range between 1 or 2 or 3 and 5 or 6 or 7), any subranges between any two exact values ​​are included (e.g., the range 1 to 7 above includes subranges 1 to 2; 2 to 6; 5 to 7; 3 to 7; 5 to 6; etc.).

[0010] Unless stated to the contrary, implied by the context, or as is customary in the art, all parts and percentages are based on weight, and all test methods are current methods as of the date of this disclosure.

[0011] The terms “comprising,” “including,” “having,” and their derivatives do not exclude the presence of any additional components or processes. The term “consistently composed of” excludes any other components or processes except those essential to operability. The term “composed of” excludes any components or processes not specifically listed.

[0012] "Ethylene-based polymers" are polymers containing more than 50 mol% of polymerizable ethylene monomers (based on the total amount of polymerizable monomers) and optionally may contain at least one comonomer. Ethylene-based polymers include ethylene homopolymers and ethylene copolymers (meaning units derived from ethylene and one or more comonomers). The terms "ethylene-based polymers" and "polyethylene" are used interchangeably. Non-limiting examples of ethylene-based polymers (polyethylene) include low-density polyethylene (LDPE) and linear polyethylene. Non-limiting examples of linear polyethylene include linear low-density polyethylene (LLDPE), ultra-low-density polyethylene (ULDPE), very low-density polyethylene (VLDPE), multi-component ethylene-based copolymers (EPE), ethylene / α-olefin multi-block copolymers (also known as olefin block copolymers (OBC)), substantially linear or linear plastisol / elastomers, and high-density polyethylene (HDPE). Generally, polyethylene can be produced using heterogeneous catalyst systems (such as Ziegler-Natta catalysts) and homogeneous catalyst systems containing Group 4 transition metals and ligand structures (such as metallocenes, non-metallocene metal centers, heteroaryl groups, isovalent aryloxy ethers, phosphine imides, etc.) in gas-phase fluidized bed reactors, liquid-phase slurry reactors, or liquid-phase solution reactors. Combinations of heterogeneous and / or homogeneous catalysts can also be used in single-reactor or dual-reactor configurations.

[0013] High-density polyethylene (or HDPE) is a homopolymer of ethylene or a polymer with at least one C3-C4 bond. 10 ethylene / α-olefin copolymers of α-olefin comonomers or C4-C8 α-olefin comonomers, with a density of 0.940 g / cc, or 0.945 g / cc, or 0.950 g / cc, or 0.953 g / cc to 0.955 g / cc, or 0.960 g / cc, or 0.965 g / cc, or 0.970 g / cc, or 0.975 g / cc, or 0.980 g / cc. HDPE can be a unimodal copolymer or a multimodal copolymer. A “unimodal ethylene copolymer” is an ethylene / C3-C8 copolymer exhibiting a single prominent peak in gel permeation chromatography (GPC) showing the molecular weight distribution. 10 α-olefin copolymers. "Multimodal ethylene copolymers" are ethylene / C4-C4 copolymers exhibiting at least two distinct peaks in the GPC showing the molecular weight distribution. 10 α-olefin copolymers. Multimodal copolymers include copolymers with two peaks (bimodal) and copolymers with more than two peaks. Non-limiting examples of HDPE include DOWN. ™ High-density polyethylene (HDPE) resin (available from The Dow Chemical Company), CONTINUUM ™ Bimodal polyethylene resin (available from Dow Chemical Company), LUPOLEN ™ HDPE products (available from LyondellBasell) and from Borealis, Ineos and ExxonMobil.

[0014] Low-density polyethylene (or "LDPE") may also be referred to as "high-pressure ethylene polymer" or "highly branched polyethylene," and is composed of ethylene homopolymer or contains at least one C3-C group with a density of 0.915 g / cc to less than 0.940 g / cc. 10 LDPE is composed of ethylene / α-olefin copolymers of α-olefins and contains long-chain branches with a wide MWD. ​​LDPE is typically produced by high-pressure free radical polymerization (in a tubular reactor or autoclave with a free radical initiator). The density of LDPE resin is typically in the range of 0.915 g / cc to 0.935 g / cc. Non-limiting examples of LDPE include MarFlex. ™ (Chevron Phillips), LUPOLEN ™ LyondellBasell and LDPE products from Dow, Borealis, INEOS, ExxonMobil, and others.

[0015] Linear low-density polyethylene (or "LLDPE") is a linear ethylene / α-olefin copolymer containing heterogeneous short-chain branched distributions, comprising units derived from ethylene and units derived from at least one C3-C group. 10 The unit cell of an α-olefin comonomer. LLDPE is characterized by very little long-chain branching (if present) compared to conventional LDPE. LLDPE has a density from 0.910 g / cc to less than 0.940 g / cc. Non-limiting examples of LLDPE include TUFLIN. ™ Linear low-density polyethylene resin (available from Dow Chemical Company), DOWLEX ™ Polyethylene resin (available from Dow Chemical Company), FINGERPRINT ™ Polyethylene resin (available from Dow Chemical Company) and MARLEX ™ Polyethylene (available from Chevron Phillips).

[0016] As used herein, a "fiber" is a thin strand of polymeric material in which the length-to-diameter ratio is greater than 10. Fibers typically have a circular or substantially circular cross-section. Other cross-sectional shapes of fibers include trefoil or flat (i.e., "ribbon") shapes. Fibers exclude membranes with relatively parallel or substantially parallel sides.

[0017] The term "meltblown fiber" refers to fibers formed by extruding molten thermoplastic material through multiple thin, typically circular, capillary dies to form molten wires or filaments, which are then introduced into a converging high-speed, typically hot gas (e.g., air) stream. This gas stream thins the molten thermoplastic filaments to reduce their diameter (which can be the diameter of microfibers). The meltblown fibers are then carried by the high-speed gas stream and deposited on a collecting surface to form a randomly dispersed meltblown fiber web. Meltblown fibers can be continuous or discontinuous, typically having an average fiber diameter of 15 micrometers or less, or 0.5 to 10 micrometers. Meltblown fiber webs can be bonded by a variety of means, including but not limited to self-bonding (i.e., self-bonding without further processing), thermocalendering, adhesive bonding, hot air bonding, needle punching, hydroentangling, and combinations thereof.

[0018] The terms “nonwoven fabric” and “nonwoven web” are used interchangeably in this document. “Nonwoven fabric” refers to a web with a structure of individual fibers or threads that are randomly inserted rather than in a identifiable manner as in knitted fabric.

[0019] "Olefin-based polymers" are polymers containing a majority mol% of polymerizable olefin monomers (based on the total amount of polymerizable monomers) and optionally containing at least one comonomer. Non-limiting examples of olefin-based polymers include ethylene-based polymers and propylene-based polymers.

[0020] The term "polymer" refers to a macromolecular compound prepared by polymerizing monomers of the same or different types. "Polymers" include homopolymers, copolymers, terpolymers, interpolymers, etc. The term "interpolymer" refers to a polymer prepared by polymerizing at least two different types of monomers or comonomers. This includes, but is not limited to, copolymers (which typically refer to polymers prepared from two different types of monomers or comonomers), terpolymers (which typically refer to polymers prepared from three different types of monomers or comonomers), tetropolymers (which typically refer to polymers prepared from four different types of monomers or comonomers), etc.

[0021] "Propylene-based polymers" are polymers that contain a major molar percentage of polymeric propylene by weight and optionally may include at least one comonomer. Propylene-based polymers typically contain at least 50 mol% of propylene-derived units based on the total amount of polymerizable monomers.

[0022] The term "spunbond" refers to the manufacture of a nonwoven fabric comprising the following steps: (a) extruding molten thermoplastic yarns from multiple fine capillaries called spinnerets; (b) quenching the yarns with a normally cooled airflow to accelerate the solidification of the molten yarns; (c) thinning the yarns by advancing them through a quenching zone with tensile tension, which can be applied by pneumatically clamping the yarns in an airflow or by winding the yarns around a mechanical stretching roller, the type commonly used in the textile fiber industry; (d) collecting the stretched yarns in a mesh (e.g., a moving screen or porous belt) on a perforated surface; and (e) bonding the mesh of loose yarns into a nonwoven fabric. Bonding can be achieved in a variety of ways, including but not limited to thermocalendering, adhesive bonding, hot air bonding, needle punching, hydroentangling, and combinations thereof. Fibers produced by spunbond manufacturing processes typically have an average fiber diameter greater than 15 micrometers.

[0023] "Superabsorbent polymer material" or "superabsorbent polymer" (or "SAP") refers to a substantially water-insoluble material that is capable of absorbing at least 10 times its weight in water in an aqueous solution containing 0.9% by weight of sodium chloride. SAP can be in the form of particles, fibers, sheets, cubes, spheres, and combinations thereof. Non-limiting examples of superabsorbent materials include synthetic hydrogel polymers and natural materials such as polysaccharides and peptides. Other suitable superabsorbent materials include hydrolyzed acrylonitrile-grafted starch, acrylic acid-grafted starch and isobutylene maleic anhydride copolymers, and mixtures thereof. Superabsorbent polymer materials can be surface-crosslinked, such that the outer surface of the superabsorbent polymer material has a higher crosslinking density than the interior of the superabsorbent polymer material.

[0024] Test methods

[0025] Average fiber diameter The average fiber diameter was measured using scanning electron microscopy (SEM). Samples were analyzed directly and placed on a needle-type sample stage using a double-sided adhesive carbon disk for SEM. The sample surface was studied using a Phenom X-Pro benchtop SEM operated at an accelerating voltage of 15 kV, and the samples were imaged using a backscattered electron detector (BSE). At least 30 different fibers were measured. The average fiber diameter was determined based on… Report, among which It is the diameter of the nth fiber.

[0026] density Density is measured using the displacement (Archimedes) method, specifically ASTM Method D792 Method B. The sample is weighed in air (dry weight) and also submerged in a fluid (wet weight). Given the density of the submerged fluid, the weight loss of the sample during immersion allows for the calculation of the sample density. A sheet of material is molded according to Annex A.1 Procedure C (cooled at 15°C) according to ASTM D4703. Upon removal from the press, cut three (triple) specimens (approximately 1.5" × approximately 0.5" × approximately 0.125") from the sheet and measure their density. For Method B, weigh the sample in air and then immerse it in a fluid (IPA, isopropanol) contained in a double-walled container, with the temperature controlled at 23°C + / - 0.1°C. Allow the sample to soak in the fluid for 8 minutes to ensure it has equilibrated to the bath temperature. Then weigh the sample while it is still immersed in the fluid. Then weigh the glass submerged in the fluid with a known dry weight and volume. Calculate the density of the immersion fluid based on the known and measured values ​​of the glass submerged (this corrects for any small deviations in the fluid density within the permissible temperature range). The density of the sample can then be calculated based on the known fluid density and the measured wet and dry sample weights.

[0027] hydrophilic-lipophilic balance valueThe HLB value (or "HLB number") is used as a measure of the ratio of a hydrophilic to a lipophilic matrix in a given surfactant or surfactant blend. It is a value from 0 to 60 and functionally defines the surfactant's affinity for water or oil. Nonionic surfactants typically have an HLB of 0 to 20. Surfactants with an HLB greater than 10 have an affinity for water, and surfactants with an HLB less than 10 have an affinity for oil.

[0028] Melt index Melt index (MI) or I2 (for ethylene-based polymers) is measured according to ASTM D 1238-10, conditions 190°C / 2.16 kg, method B, and reported in grams eluted per 10 minutes.

[0029] melt flow rate Melt flow rate (MFR) (for propylene-based polymers) is measured according to ASTM D 1238-10, conditions 230°C / 2.16 kg, method B, and reported in grams eluted per 10 minutes.

[0030] Molecular weight distribution The molecular weight of the polymer was determined using gel permeation chromatography (GPC). The GPC system consisted of a PolymerChar GPC-IR (Valencia, Spain) high-temperature GPC chromatograph equipped with an internal IR5 infrared detector (IR5). The autosampler chamber was set to 160°C and the column chamber to 150°C. Four Agilent "Mix A" 30 cm 20 μm linear mixed-bed columns were used. The chromatographic solvent used was 1,2,4-trichlorobenzene containing 200 ppm butylated hydroxytoluene (BHT). The solvent source was bubbled with nitrogen. The injection volume used was 200 μL, and the flow rate was 1.0 mL / min.

[0031] The calibration of the GPC column was performed using at least 20 polystyrene standards with narrow molecular weight distributions ranging from 580 g / mol to 8,400,000 g / mol, arranged in a six-component "cocktail" mixture, with individual molecular weights spaced at least ten times apart. These standards were purchased from Agilent Technologies. For molecular weights equal to or greater than 1,000,000 g / mol, 0.025 g of polystyrene standard was prepared in 50 mL of solvent, while for molecular weights less than 1,000,000 g / mol, 0.05 g of polystyrene standard was prepared in 50 mL of solvent. The polystyrene standards were dissolved at 80 °C by gentle stirring for 30 minutes. The peak molecular weights of the polystyrene standards were converted to ethylene / α-olefin interpolymer molecular weights using the following equation (as described by Williams and Ward in J. Polym. Sci., Polym. Let., 6, 621 (1968)):

[0032]

[0033] Where M is the molecular weight, A has a value of 0.4315, and B equals 1.0.

[0034] A fifth-order polynomial was used to fit the corresponding ethylene / α-olefin interpolymer-equivalent calibration point. A small adjustment was made to A (from approximately 0.39 to 0.44) to correct for column resolution and band broadening effects, resulting in NIST standard NBS 1475 with a molecular weight of 52,000 g / mol.

[0035] Total plate counts were performed on the GPC column assembly using eicosane (prepared as 0.04 g in 50 mL of TCB and dissolved over 20 minutes with gentle stirring). Plate counts and symmetry were measured by injection at 200 μL according to the following equations (Equation 2) and (Equation 3):

[0036]

[0037] Where RV is the retention volume in milliliters, peak width is in milliliters, peak maximum is the maximum height of the peak, and half height is half the height of the peak maximum.

[0038]

[0039] Where RV is the retention volume in milliliters, and peak width is in milliliters, peak maximum is the position of the peak maximum, one-tenth height is one-tenth of the peak maximum height, and a subsequent peak refers to the tail of a peak at a retention volume later than the peak maximum, while a preceding peak refers to the front of a peak at a retention volume earlier than the peak maximum. The plate count of the chromatographic system should be greater than 22,000, and the symmetry should be between 0.98 and 1.22.

[0040] Samples were prepared semi-automatically using PolymerChar Instrument Control software, with a target sample weight of 2 mg / ml. Solvent (containing 200 ppm BHT) was added to a pre-bubbled, diaphragm-capped vial via a PolymerChar high-temperature autosampler. The sample was dissolved at 160°C for 3 hours with "low-speed" oscillation.

[0041] M n(GPC) M w(GPC) and M z(GPC) The calculations are based on GPC results obtained using the internal IR5 detector (measurement channel) of the PolymerChar GPC-IR chromatograph according to equations 5a-c, using PolymerChar GPCOne. ™ The software calculates the IR chromatograms (IR) at each equidistant data collection point i after subtracting the baseline. i ) and the equivalent molecular weight (in g / mol) of the ethylene / α-olefin interpolymer obtained from the narrow standard calibration curve at point i according to Equation 1. 聚乙烯,i Subsequently, a GPC molecular weight distribution (GPC-MWD) plot (wt) can be obtained. GPC (lgMW) to the lgMW plot, where wt GPC (lgMW) is the weight fraction of interpolymer molecules with a molecular weight of lgMW. Molecular weight is expressed in g / mol and wt. GPC (lgMW) follows Equation 4.

[0042]

[0043] Number average molecular weight M n(GPC) Weight-average molecular weight M w(GPC) and z-average molecular weight M z(GPC) It can be calculated using the following equation.

[0044]

[0045] Molecular weight distribution can be represented as M w(GPC) / M n(GPC) .

[0046] To monitor deviations over time, a flow rate marker (decane) was introduced into each sample via a micropump controlled by a PolymerChar GPC-IR system. This flow rate marker (FM) was used to linearly correct the pump flow rate (nominal flow rate) for each sample by comparing the RV (RV(FM sample)) of the corresponding decane peak within the sample with the RV (RV(FM calibrated)) of the decane peak within the narrow standard calibration. It was then assumed that any variation in the decane marker peak time was linearly related to the flow rate (effective flow rate) over the entire run. To facilitate the highest accuracy in RV measurement of the flow marker peak, a least-squares fitting procedure was used to fit the peak values ​​of the flow marker concentration chromatogram to a quadratic equation. The first derivative of the quadratic equation was then used to solve for the true peak position. After calibrating the system based on the flow marker peak, the effective flow rate (relative to narrow standard calibration) was calculated according to Equation 6. Processing of the flow marker peak was performed via PolymerChar GPCOne. ™ The software is complete. An acceptable flow rate correction should ensure that the effective flow rate is within 0.5% of the nominal flow rate.

[0047] Detailed Implementation

[0048] This disclosure provides an article of manufacture. In one embodiment, the article of manufacture comprises (1) a nonwoven meltblown fiber web and (2) a plurality of superabsorbent polymer particles. The fibers have an average fiber diameter of 1 micrometer to 15 micrometers. Each fiber comprises (A) an ethylene / α-olefin copolymer having (i) a density of 0.920 g / cc to 0.940 g / cc and (ii) a melt index of 50 g / 10 min to 250 g / 10 min. Each fiber also comprises (B) two or more surfactants. Each surfactant has an HLB value of 0.5 to 10.0. The article of manufacture also comprises (2) a plurality of superabsorbent polymer particles. These superabsorbent polymer particles are dispersed within the fiber web.

[0049] 1. Network

[0050] The product includes (1) a nonwoven meltblown fiber web. Each fiber is composed of an ethylene / α-olefin copolymer. The ethylene / α-olefin-based copolymer can be ethylene / C3-C 10α-olefin copolymers or ethylene / C4-C8 α-olefin copolymers. These ethylene / α-olefin-based copolymers have a density of 0.920 g / cc to 0.940 g / cc and a melt index (MI) of 20 g / 10 min to 250 g / 10 min. Non-limiting examples of suitable ethylene-based polymers include ethylene plastisols / elastomers, high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), ethylene / α-olefin multiblock copolymers, and combinations thereof.

[0051] In one embodiment, the ethylene / α-olefin copolymer is an ethylene / C4-C8 α-olefin copolymer or an ethylene / hexene copolymer having one, some, or all of the following properties:

[0052] (i) densities ranging from 0.920 g / cc to 0.940 g / cc, or from 0.925 g / cc to 0.937 g / cc; and / or

[0053] (ii) I2 at concentrations of 20 g / 10 min to 250 g / 10 min, or 20 g / 10 min to 180 g / 10 min, or 75 g / 10 min to 200 g / 10 min, or 90 g / 10 min to 175 g / 10 min, or 155 g / 10 min to 185 g / 10 min, or 175 g / 10 min to 185 g / 10 min; and / or

[0054] (iii) Mw / Mn of 2.0 to 6.0, or 2.0 to 5.0, or 3.5 to 4.5, or 4.2.

[0055] In one embodiment, the fiber comprises a blend of two ethylene / C6-C8 α-olefin copolymers.

[0056] In addition to the ethylene / α-olefin copolymer, each fiber contains at least two surfactants. Each fiber may contain two, three, four, five, or more surfactants. Each surfactant has an HLB value of 0.5 to 10.0, or 2.0 to 7.0, or 1.0 to 5.0.

[0057] In one embodiment, each fiber includes a first surfactant and a second surfactant. The first surfactant is a nonionic surfactant, which is a first ethoxylated aliphatic alcohol having an HLB value of 2.0 to 6.0, or 2.0 to less than 5.0, or 2.0 to 4.0. The second surfactant is a nonionic surfactant, which is a second ethoxylated aliphatic alcohol having an HLB value of 3.0 to 7.0, or 4.0 to 6.0, or 4.5 to 6.0, or 4.5 to 5.0.

[0058] In one embodiment, the first surfactant is a first ethoxylated aliphatic alcohol with an HLB value of 2.0 to 6.0 and having the formula (1).

[0059]

[0060] in

[0061] n is an integer between 24 and 34, or between 28 and 32, and

[0062] x is between 1 and 5.

[0063] The second surfactant is a second ethoxylated aliphatic alcohol with an HLB value of 3.0 to 7.0 and having formula (2).

[0064]

[0065] in

[0066] Where m is an integer from 8 to less than 24, or from 10 to 20, and

[0067] y ranges from 1 to 6.

[0068] In one embodiment, a first surfactant and a second surfactant are introduced into the ethylene / α-olefin copolymer via a masterbatch or otherwise melt-blended. The first and second surfactants are uniformly mixed into a carrier resin to form a masterbatch. The carrier resin of the masterbatch is a second ethylene-based polymer. The second ethylene-based polymer differs from the ethylene / α-olefin copolymer in at least one property of density and / or melt index.

[0069] In one embodiment, the second ethylene-based polymer is an ethylene / C4-C8 α-olefin copolymer having the following properties:

[0070] (i) a density of 0.94 g / cc to 0.97 g / cc, or 0.95 g / cc to 0.96 g / cc; and / or

[0071] (ii) Melt index (MI) of 10 g / 10 min to 40 g / 10 min, or 20 g / 10 min to 40 g / 10 min, or 25 g / 10 min to 30 g / 10 min.

[0072] Each fiber may also contain additional optional components, such as one or more additives. Such additives include, but are not limited to, antistatic agents, color enhancers, dyes, lubricants, fillers, pigments, primary antioxidants, secondary antioxidants, processing aids, UV stabilizers, antiblocking agents, slip agents, tackifiers, flame retardants, antimicrobial agents, deodorants, antifungal agents, and combinations thereof. Additives may be present in the fiber in an amount of 0% by weight, or from 0.1% by weight to 10% by weight, or from 0.1% by weight to 5% by weight, or from 0.1% by weight to 1.0% by weight, based on the total weight of the fiber.

[0073] 2. Superabsorbent polymer (SAP)

[0074] The article of the present invention also includes (2) a plurality of superabsorbent polymer particles. The SAP particles have an average particle size of 100 micrometers to 800 micrometers. A non-limiting example of a suitable material for superabsorbent polymer is Artic Gel 1010 superabsorbent polymer from BASF.

[0075] This product can be prepared by melt-blowing multiple fibers composed of an ethylene / α-olefin copolymer and two or more surfactants, and by metering multiple superabsorbent polymer particles between the fibers, followed by deposition of the fiber web structure onto a conveyor belt. As used herein, the term "metered superabsorbent polymer material" refers to depositing a specific amount of superabsorbent polymer particles onto or within a nonwoven matrix such that the superabsorbent polymer material does not agglomerate on or within the nonwoven material. This method produces a hybrid structure (or, in other words, a composite structure) in which the superabsorbent polymer particles are uniformly dispersed (or, in other words, uniformly mixed) within the multiple fibers.

[0076] In one embodiment, the article includes

[0077] (1) 90% to 50% by weight, or 85% to 55% by weight, of nonwoven fiber web (based on the total weight of the nonwoven web and SAP particles), these fibers having an average fiber diameter of 1 micrometer to 15 micrometers, or 5 micrometers to 10 micrometers.

[0078] (A) Each fiber is composed of some or all of the following properties: ethylene / C4-C8 α-olefin copolymer or ethylene / hexene copolymer.

[0079] (i) densities ranging from 0.920 g / cc to 0.940 g / cc, or from 0.925 g / cc to 0.937 g / cc; and / or

[0080] (ii) I2 at concentrations of 20 g / 10 min to 250 g / 10 min, or 20 g / 10 min to 180 g / 10 min, or 75 g / 10 min to 200 g / 10 min, or 90 g / 10 min to 175 g / 10 min, or 155 g / 10 min to 185 g / 10 min, or 175 g / 10 min to 185 g / 10 min; and / or

[0081] (iii) Mw / Mn of 2.0 to 6.0, or 2.0 to 5.0, or 3.5 to 4.5, or 4.2;

[0082] (B1) A first surfactant of 500 ppm to 10,000 ppm, or 1,000 ppm to 5,000 ppm, wherein the first surfactant is a nonionic surfactant having an HLB value of 2.0 to 6.0, or 2.0 to 4.5, or 2.0 to 4.0 (wherein ppm is based on the total weight of the fiber).

[0083] (B2) A second surfactant of 500 ppm to 10,000 ppm, or 1,000 ppm to 5,000 ppm, wherein the second surfactant is a nonionic surfactant having an HLB value of 3.0 to 7.0, or 4.0 to 6.5, or 4.5 to 6.5 (wherein ppm is based on the total weight of the fiber), and

[0084] (C) 0.1% to 15% by weight, or 0.1% to 5% by weight, or 0.1% to 3% by weight of a carrier resin, wherein the weight percentages of (A), (B1), (B2) and (C) are based on the total weight of the fibers, and the carrier resin is a second ethylene / C4-C8 α-olefin copolymer having the following characteristics:

[0085] (i) a density of 0.94 g / cc to 0.97 g / cc, or 0.95 g / cc to 0.96 g / cc; and / or

[0086] (ii) Melt index (MI) of 10 g / 10 min to 40 g / 10 min, or 20 g / 10 min to 40 g / 10 min, or 25 g / 10 min to 30 g / 10 min.

[0087] (2) 10% to 50% by weight, or 15% to 45% by weight of multiple SAP particles (wherein the weight percentages of (1) and (2) are based on the total weight of the nonwoven web and the SAP particles), which are composed of a sodium acrylate-based polymer and have an average particle size of 100 micrometers to 800 micrometers.

[0088] In one implementation, the product is a diaper, feminine hygiene products (feminine pads, tampons), adult incontinence products, face masks, wipes, wound care products (bandages, gauze), and tissues.

[0089] Unbound by any particular theory, the applicant discovered that the (i) absorption rate and (ii) absorption capacity of SAP particles are increased due to the ethylene / α-olefin copolymer having an average fiber diameter of 1 to 15 micrometers and containing at least two surfactants with HLB values ​​of 0.5 to 10. The first and second surfactants co-crystallize with the ethylene / α-olefin copolymer, thus providing better compatibility with the fibers of the nonwoven web. The SAP particles exhibit high ionic strength and are capable of absorbing water upon swelling. In addition to the mobility of water on the ethylene / α-olefin copolymer fibers, interfiber slippage occurs when the ionic SAP particles swell on the surface of wettable polyethylene fibers with nonionic surfaces. The smaller fiber size (1 to 15 micrometers) provides fiber flexibility and allows the ionic SAP to swell freely, resulting in a higher absorption rate of aqueous liquids. Each fiber has a nonionic hydrophilic surface due to the action of the two surfactants. This enables rapid wetting and allows aqueous liquids to flow freely between the fibers and be absorbed by the SAP.

[0090] Embodiments of this disclosure will now be described in detail by way of example and not by way of limitation.

[0091] Example

[0092] 1. Materials

[0093] The materials of the embodiments of the invention (“IE”) and the comparative samples (“CS”) are listed in Tables 1A and 1B below.

[0094] Table 1A

[0095]

[0096] PE-1 is produced using a catalyst system in a gas-phase polymerization process, which includes the main catalyst UCAT. ™ J (commercially available from Univation Technologies, LLC, Houston, TX) and the co-catalyst triethylaluminum (TEAL). UCAT ™The J catalyst was partially activated by contacting a suitable amount of a 40% mineral oil solution of tri-n-hexyl aluminum (TNHA) at room temperature. The combined catalyst slurry mixture was fed via a stirred tank to provide a residence time of at least 1 hour before being fed into the reactor. The polymerization reaction was continued after equilibrium was reached under the conditions shown in Table 1B below. Polymerization was initiated by continuously feeding the catalyst slurry and co-catalyst (trialkyl aluminum, particularly triethyl aluminum or TEAL) along with ethylene, hydrogen, and 1-hexene into a fluidized bed of polyethylene particles. Inert gases, nitrogen, and isopentane constituted the residual pressure in the reactor. The granular product was continuously removed from the reactor and purged to remove residual hydrocarbons. The granular product was then combined with additives (1000 ppm zinc stearate, 200 ppm Irganox 1076) in an extruder to form the final resin granules.

[0097] Table 1B — Polymerization conditions for PE-1

[0098]

[0099] PE-2 was prepared according to Example 3 of International Publication No. WO2020 / 106797, the contents of which are incorporated herein by reference.

[0100] 2. Preparation of fiber and nonwoven webs

[0101] Use such as Figure 2The meltblown production line shown is used to prepare samples, equipped with two meltblown beams. The two beams are arranged such that one beam (upper beam 21) is positioned relatively higher than the other beam (lower beam 22). The two beams are aligned so that hot air streams from both beams are directed to the same location on the vacuum drum. SAP is metered into the meltblown fibers using a SAP injector 23 located between the two beams. Each meltblown beam is equipped with a single-screw extruder, a melt pump, and a multi-row meltblown die designed by Biax-Fiberfilm. The meltblown die distributes the molten polymer into an array of cylindrical capillaries (0.5 mm orifice diameter), each surrounded by a ring-shaped, decaying hot air stream. Immediately after leaving the capillaries, the molten polymer is stretched by the decaying hot air to form continuous fine fibers 210 and 220. The fibers are then cooled and solidified by quenched air. When the SAP injector is turned on, SAP granules 230 are fed into and mixed with the solid fibers before the SAP / fiber web is applied to the vacuum drum 24, and are evenly dispersed among the fibers. The vacuum drum is rotated and the SAP / fiber web is conveyed to the winder 25. The SAP / fiber composite web is then wound on the winder to form a roll. The throughput of both the upper and lower meltblown beams is set to 0.2 g / hole / min. The die-to-collector distance (DCD) is set to 31 cm. The vacuum drum blower is set to 100%. Tables 2A and 2B show the process conditions used to produce the sample web. Two surfactant masterbatches, Techsurf PPM 15560 and Techsurf PM 19668, are used. The surfactant masterbatches are dry-mixed with PE-1, PE-2, or PP in a certain proportion before being fed into the hopper of the single-screw extruder.

[0102] Table 2A. Conditions for Upper Beam Meltblown Line

[0103]

[0104] Table 2B. Conditions of the lower beam meltblown line

[0105]

[0106] Table 3 shows the materials used in the upper and lower beam extruders.

[0107] Table 3

[0108]

[0109] Samples were cut from SAP / fiber composite products into 2-inch × 2-inch pieces for fiber diameter measurement and liquid absorption testing. The average fiber diameter of all samples ranged from 5 to 10 micrometers. The fibers were continuous and longer than 10 cm.

[0110] Tables 4A, 4B, and 4C show the results of liquid absorption.

[0111] Table 4A — Average sample weight ("ASW") for each soaking time (grams)

[0112]

[0113] Table 4B — Average liquid absorption ("ALU") for each soaking time (grams)

[0114]

[0115] Table 4C — Average liquid update per unit weight of SAP for each soaking time ("ALU / SAP") (grams)

[0116]

[0117] The applicant found that nonwoven webs of the ethylene / α-olefin copolymer fibers of the present invention, having two surfactants and SAP particles with an average fiber diameter of 1 to 15 micrometers, exhibited higher liquid renewal (ALU) than nonwoven webs of propylene-based fibers and the same SAP particles.

[0118] Unbound by any particular theory, fibers with a diameter of 1 to 15 micrometers, composed of the ethylene / α-olefin copolymer of the present invention and containing two surfactants, provide improved lubricity (i.e., reduced friction) for SAP particles while maintaining a suitable support structure to hold the SAP particles in the proper position within the nonwoven web. This combination of lubricity and support provided by the fibers promotes greater and faster liquid absorption capacity of the SAP particles. The improved liquid absorption capacity provides the articles of the present invention with the same or greater absorption capacity as conventional articles, but using fewer (10% to 50% by weight) SAP particles.

[0119] Techsurf PPM 15560 masterbatch is not a suitable surfactant masterbatch because the carrier resin is polypropylene. When Techsurf PPM 15560 masterbatch is blended with PE-1 and / or PE-2, fiber breakage occurs during the meltblown process due to the incompatibility between the polypropylene carrier resin and the ethylene / α-olefin copolymer in the fiber. The applicant found that Techsurf PM19668 masterbatch contains a polyethylene carrier resin with a density (0.94 g / cc to 0.97 g / cc) and MI (10 g / 10 min to 40 g / 10 min) suitable for uniformly dispersing the first and second surfactants into the fiber and allowing these surfactants to diffuse to the fiber surface.

[0120] It is particularly desirable that this disclosure is not limited to the embodiments and descriptions contained herein, but includes modifications of those embodiments, including portions of embodiments appearing within the scope of the following claims and combinations of elements of different embodiments.

Claims

1. An article comprising: (1) A nonwoven meltblown fiber web, wherein the fibers have an average fiber diameter of 1 micrometer to 15 micrometers, the fibers comprising (A) An ethylene / α-olefin copolymer, the copolymer having (i) densities ranging from 0.920 g / cc to 0.940 g / cc, (ii) Melt index from 50 g / 10 min to 250 g / 10 min; and (B) Two or more surfactants, each having an HLB value of 0.5 to 10.0; and (2) Multiple superabsorbent polymer particles (SAP) dispersed in the network.

2. The article of claim 1, wherein the article comprises (C) A carrier resin for carrying the two or more surfactants, the carrier resin comprising a second ethylene / α-olefin copolymer having (i) densities ranging from 0.930 g / cc to 0.970 g / cc; and (ii) Melt index of 20 g / 10 min to 50 g / 10 min.

3. The article according to any one of claims 1 to 2, wherein each fiber comprises The first surfactant, ranging from 500 ppm to 10000 ppm; and A second surfactant of 500 ppm to 10,000 ppm, wherein the ppm is based on the total weight of the fibers.

4. The article according to any one of claims 1 to 3, wherein the first surfactant is a first ethoxylated aliphatic alcohol having formula (1). C n H 2n+1 (OCH2CH2) x OH in n is an integer between 24 and 34, and x is between 1 and 5.

5. The article of claim 4, wherein the ethoxylated aliphatic alcohol has an HLB value of 2.0 to 6.

0.

6. The article according to any one of claims 1 to 5, wherein the second surfactant is a second ethoxylated aliphatic alcohol having formula (2). C m H 2m+1 (OCH2CH2) y OH in m is an integer from 8 to less than 24, and y ranges from 1 to 6.

7. The article of claim 6, wherein the second ethoxylated aliphatic alcohol has an HLB value of 3.0 to 7.

0.

8. The article of manufacture according to any one of claims 1 to 7, wherein the article of manufacture comprises: (1) A nonwoven fiber web, wherein the fibers have an average fiber diameter of 1 micrometer to 15 micrometers, the fibers comprising (A) An ethylene / C4-C8 α-olefin copolymer, wherein the copolymer has (i) densities ranging from 0.920 g / cc to 0.940 g / cc, (ii) Melt index from 50 g / 10 min to 150 g / 10 min (B1) A first surfactant of 500 ppm to 10000 ppm, wherein the first surfactant is a nonionic surfactant having an HLB value of 2.0 to 6.0; (B2) A second surfactant of 500 ppm to 10000 ppm, wherein the second surfactant is a nonionic surfactant having an HLB value of 3.0 to 7.0; (C) 0.1% to 15% by weight of carrier resin, and the weight percentages of (A), (B1), (B2) and (C) are based on the total weight of the fibers; and (2) 10% to 50% by weight of a plurality of SAP particles uniformly dispersed in the net, wherein the weight percentage is based on the total weight of (1) and (2).

9. The article of claim 1 to 8, wherein the article is selected from the group consisting of diapers, feminine hygiene products, adult incontinence products, face masks, wipes, wound care products, and tissues.

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