JP2009504933A - Meltblown nonwoven layers and composite structures based on propylene - Google Patents

Abstract

  The present invention relates to propylene-based nonwoven layers produced by a meltblown process and laminates incorporating such layers. The meltblown layer of the present invention comprises a propylene copolymer characterized by having a crystallinity of less than 50 percent. The meltblown layer of the present invention exhibits improved combined properties of extensibility and tensile strength. The laminated structure of the present invention is characterized by the combined properties of a low bending modulus and high peel strength.

Description

  The present invention relates to propylene-based nonwoven layers produced by a meltblown process and laminates incorporating such layers. The meltblown layer of the present invention comprises a propylene copolymer characterized by having a crystallinity of less than 50 percent. The meltblown layer of the present invention exhibits improved combinatorial properties of extensibility and tensile strength, and a spunbond layer, particularly a spun made of a polyethylene-based material comprising at least a portion of its surface. When bonded to the bond layer, it exhibits significantly better adhesive strength.

  Nonwoven webs or nonwovens are very suitable for use in a variety of products such as bandage materials, apparel, disposable diapers, and other personal hygiene products including wet-type wipes. Nonwoven webs having a high level of strength, softness and abrasion resistance are very suitable for water absorbent clothing, such as diapers, urine leak-proof briefs, training pants, feminine hygiene clothing and the like. For example, in the case of disposable diapers, it is highly desirable to have a soft and strong non-woven component, such as a topsheet or backsheet (also known as an outer cover).

  As used herein, the term “nonwoven web” refers to a web that has an interlaid individual fiber or yarn structure, but not in a regular repeating manner. Nonwoven webs have heretofore been formed by a variety of processes, such as carding processes including air laying processes, melt blowing processes, spunbonding processes, and bonded carded web processes. Each of these various processes has its own strengths and weaknesses. For example, spunbonded webs tend to have higher tensile strength than meltblown webs, while meltblown processes tend to yield webs with enhanced liquid barrier properties compared to spunbond nonwovens.

  Propylene-based polymers, particularly homo-polypropylene (hPP), are well known in the art and have long been used in the manufacture of fibers. Fabrics made from hPP, especially non-woven fabrics, exhibit high elastic modulus, but lack elasticity and flexibility. Nevertheless, these fabrics are widely incorporated into multicomponent articles such as diapers, wound dressings, feminine hygiene products and the like.

  In comparison, polyethylene-based elastomers and fibers and fabrics made from these polymers tend to exhibit low elastic modulus and good elasticity, but these materials have low toughness and viscosity. However, there is also a tendency to present a feel that is generally considered unacceptable for many applications.

  The manufacture of multi-component articles typically includes a number of steps (eg, rolling / unrolling steps, cutting steps, bonding steps, etc.), and the web lacking tensile strength is one or more of these. The tensile strength of the nonwoven and the toughness of the fibers are important because it may not be possible to survive this step. Also, fibers with high tensile strength are relatively less susceptible to line interruptions, and therefore high productivity can be obtained from the production line, so fibers with high tensile strength (also known as toughness) Superior to fibers with low tensile strength. In addition, many product end uses typically require a certain level of tensile strength specific to the function of the component. The tensile strength must be balanced with the cost of the process used to achieve higher tensile strength or higher toughness. An optimized fabric has a minimum amount of material consumption (basis weight) to achieve the minimum tensile strength necessary for the manufacture and end use of its fibers, components (eg, nonwovens) and articles.

  Hand feel is another important aspect for many nonwoven structures, especially nonwoven structures intended for use in the hygiene and medical fields. Low elastic modulus is one aspect of touch. Fabrics made from fibers having a low modulus are equivalent in all other respects and give a “softer” feel than fabrics made from fibers having a high modulus. Also, fabrics composed of fibers with lower elastic modulus also exhibit lower bending stiffness, which is reflected in good drapability and good fit. In contrast, fabrics made from fibers with higher elastic modulus, such as hPP, give a rough feel and lack of draping properties is sufficient to produce poor fit results. is there. Fabrics made from polyethylene-based elastomers are also typically undesired to the skin, characterized by various descriptors such as stickiness, stickiness, stickiness, rubbery feel or moistness There is a tendency to lack proper touch.

  The extensibility / elasticity of the fibers allows articles made from fibers with such properties to fit more closely with the body in all situations, so that these properties provide good comfort and fit Is another important criterion for non-woven structures, especially non-woven structures used in hygiene and medical applications. Diapers with elastic components are generally less sagging when the body size and shape and movement change. As the fit improves, the user's general well being is improved by improved comfort, reduced leakage, and a closer similarity to the article's cotton underwear.

  Accordingly, a nonwoven meltblown layer that exhibits high tensile strength, good extensibility, and adequate feel is desirable, and such a nonwoven meltblown layer is an embodiment of the present invention. Such stretch / elastic meltblown fabrics are a specific class known as propylene-based plastomers and elastomers without the need to blend with substantial amounts of higher toughness materials such as hPP. It was discovered that it can be made from polypropylene. Such propylene-based plastomers and elastomers can be characterized by one or more of the following characteristics. Crystallinity less than 50 percent; flex modulus less than 50 kpsi; melting point less than about 140 ° C. (and even less than about 130 ° C.); and / or heat of fusion less than 80 J / g. The propylene-based polymer preferably comprises a copolymer of propylene and an α-olefin, and the α olefin is preferably ethylene. The ethylene in this preferred embodiment is preferably present in an amount from 3 weight percent to 20 weight percent of the propylene-based polymer. Of the present propylene-based polymers, propylene-based polymers having ethylene in an amount of 9 to 20 weight percent are more elastomeric. Such polymers can be referred to as propylene-based elastomers (PBE). This preferred propylene-based polymer has an MWD of 2 to 4. The propylene-based polymer can also typically have a melt flow rate in the range of 1 g / 10 min to 100 g / 10 min (before use of any rheology modifier). Accordingly, nonwoven meltblown layers made from propylene-based plastomers and elastomers without substantial amounts (e.g., greater than about 10 weight percent (10 weight percent)) of hPP can be used in the present invention. It is an aspect. All percentages specified are weight percentages unless otherwise specified.

As such, for example, these nonwovens can be advantageously used in filtration applications, or they can include other nonwoven materials and be combined with other materials. These structures, at a basis weight of 25 gsm, 100 mm H ₂ O, preferably have a hydrohead (hydrohead) performance from the 200 mm H ₂ O to 800 mm H ₂ O. Higher hydrohead performance could be achieved by using a larger basis weight.

  By using in combination with other materials, such as another nonwoven, film, apertured film, fiber, woven fabric or the like, synergistic properties will be achieved. It is recognized that performance requirements can vary depending on the application. As a result, the invention and the use of various embodiments of the invention can take many forms, without being limited to the description provided.

Due to the relative strengths and weaknesses associated with the various different processes and materials used to make nonwovens, often it consists of more than one layer to achieve better balanced properties A composite structure is used. Such structures are specified by letters designating various layers, such as SM for a two layer structure consisting of a spunbond layer and a meltblown layer, SMS for a three layer structure, or more generally an SM _x S structure. Often. In order to maintain the structural integrity of such composite structures, the layers must be bonded together. Common bonding methods include point bonding, adhesive lamination, and other methods known to those skilled in the art. As long as other desirable properties such as breathability and flexural modulus are kept to a certain degree, increasing the bond strength between those layers is a continuing effort in the art to provide a more durable structure. Goal.

  However, the poor bond strength between the layers is due to the fact that polyethylene materials (including bicomponent fibers where polyethylene forms at least part of the surface of the bicomponent fibers) are used to make one layer and propylene materials such as homopolymer polypropylene ("HPP") or random copolymer polypropylene ("RCP") and the like are particularly problematic when used in adjacent layers. Accordingly, it is particularly desirable to improve the bond strength between a polyethylene-based layer and a polypropylene-based layer in a nonwoven composite structure.

  Also, meltblown fabrics made from this particular class of polypropylene-based materials provide superior bond strength to spunbond layers made from fibers with surfaces made from polyethylene-based materials. Was also found. In addition to providing excellent bond strength between the meltblown and spunbond layers, the use of these polymers for use in meltblown nonwoven webs is a composite where the meltblown layer contains a substantial amount of hPP or RCP. Increased overall softness was observed compared to the material.

  Another aspect of the present invention is a nonwoven laminate comprising a meltblown nonwoven layer and a spunbond nonwoven layer, wherein the meltblown layer is characterized by having one or more of the following characteristics: A meltblown fiber comprising a polymer of Crystallinity less than 50 percent; flexural modulus less than 50 kpsi; melting point less than about 140 ° C .; and / or heat of fusion less than 80 J / g. The propylene-based polymer preferably comprises a copolymer of propylene and an α-olefin, and the α olefin is preferably ethylene. The ethylene in this preferred embodiment is preferably present in an amount from 3 weight percent to 20 weight percent of the propylene-based polymer. This preferred propylene-based polymer has an MWD of 2 to 4. The preferred propylene-based polymer also has a melt flow rate (before use of any rheology modifier) in the range of 1 g / 10 min to 100 g / 10 min.

  In another aspect of the nonwoven laminate of the present invention, the spunbond layer comprises fibers in which the polyethylene-based material includes at least a portion of the surface of the fibers. The spunbond layer in the nonwoven laminate of the present invention may comprise a composite fiber, where the composite fiber is preferably a sheath-core structure. Alternatively, the spunbond layer may include monofilament fibers (ie, the fibers have a uniform cross section).

  Another aspect of the invention is a nonwoven laminate structure comprising at least two nonwoven layers, the nonwoven laminate structure having an overall bending modulus of less than 0.005 Nmm and a width of 2 N / width 5 cm. Characterized by having a large peel strength between nonwoven layers.

  As used herein, the term “nonwoven web” or “nonwoven fabric” or “nonwoven” is not a regular repeating manner, but refers to a web having an interleaved individual fiber or yarn structure. To express. Nonwoven webs have heretofore been formed by various processes such as carding processes including air laying processes, melt blowing processes, spunbonding processes, and bonded carded web processes.

  As used herein, the term “melt blown” refers to a molten thermoplastic material as a melted yarn or filament through a plurality of fine, usually circular die capillaries, as a high velocity gas (eg, air). Represents the process of extruding into a stream, wherein the high-speed gas stream described above attenuates the filaments of the molten thermoplastic material and reduces the diameter of those filaments, the diameter of which goes up to the diameter of the ultrafine fibers And get. These meltblown fibers are then carried by the high velocity gas stream and are deposited on the collection surface to form a web of randomly dispersed meltblown fibers.

  As used herein, the term “spunbonded” refers to extruding molten thermoplastic material as filaments from a plurality of fine, usually circular capillaries having the diameter of the filament being extruded, Thereafter, the process of rapidly reducing the diameter by drawing the fibers and collecting the fibers on the substrate is represented.

  As used herein, the term “superfine fibers” refers to small diameter fibers having an average diameter not exceeding about 100 microns. The fibers used in the present invention, in particular spunbond fibers and meltblown fibers, can be ultrafine fibers. More particularly, the spunbond fibers may advantageously be fibers having an average diameter of 15 to 30 microns and having a denier value of 1.5 to 3.0, whereas meltblown fibers May be a fiber having an average diameter of less than about 30 microns, more preferably a fiber having an average diameter of less than about 15 microns, and even more preferably a fiber having an average diameter of less than about 12 microns. . It is also envisioned that these meltblown fibers can have even smaller average diameters, for example, 10 microns, 8 microns, and even less than 5 microns.

  As used herein, the term “polymer” includes, but is not limited to, generally homopolymers, copolymers such as block copolymers, graft copolymers, random and alternating copolymers, terpolymers, etc. As well as blends and modifications thereof. Further, unless expressly limited otherwise, the term “polymer” is intended to include all possible geometric configurations of the material. These configurations include, but are not limited to, isotactic, syndiotactic and random symmetries.

  As used herein, the term “polypropylene-based plastomer (PBP) or elastomer (PBE)” (collectively these may be referred to as “PBPE”) is less than about 100 joules / gm. A reactor grade copolymer of propylene with a heat of fusion of and a MWD <3.5. PBP generally has a heat of fusion of less than about 100 joules / gram, while PBE generally has a heat of fusion of less than about 40 joules / gram. The PBP typically has a weight percent ethylene ranging from 3 weight percent ethylene to 10 weight percent ethylene, and in the case of elastomeric PBE, 10 weight percent ethylene to 15 weight percent ethylene. Has an ethylene content of up to.

  As used herein, the term “extensibility” is subject to stretching to a strain of at least about 50 percent without suffering a catastrophic failure when biasing force is applied, more preferably at least about 70 percent. Any nonwoven material that can be stretched to a strain of.

  The nonwoven material of the present invention preferably has a basis weight (weight per unit area) from 10 grams per square meter (gsm) to 100 gsm. The basis weight may be from 15 gsm to 60 gsm, and in one embodiment, the basis weight may be 20 gsm.

  As used herein, the term “tensile strength” refers to a given basis weight when a nonwoven is pulled to break in either the flow direction (MD) or the width direction (CD). Represents the peak force for. This peak force may or may not correspond to the force at break or the strain at break. “Elongation” refers to the strain corresponding to the tensile strength, unless specified otherwise.

The first aspect of the invention is measured in pounds per inch wide and normalized to a basis weight of 20 gsm when the elongation is between 20 percent and 675 percent [-0. It is a meltblown fabric having an MD peak tension (F _MD ) represented by greater than [00143 × Elongation (Percent) +0.823]. If elongation is greater than about 675 percent, F _MD is greater than about 0.1 lbs (lb). The meltblown fabric includes at least one copolymer with at least about 50 weight percent units derived from propylene and at least about 5 weight percent units derived from a comonomer other than propylene.

  The copolymer is a PBPE having a MWD <3.5 and having a heat of fusion of less than about 90 joules / gm, preferably less than about 70 joules / gm, more preferably less than about 50 joules / gm. is there. When ethylene is used as a comonomer, the PBPE is 3 to 15 weight percent ethylene, or 5 to 14 weight percent ethylene, or 9 weight percent of the propylene-based elastomer or plastomer. To 12 weight percent ethylene. Suitable propylene-based elastomers and / or plastomers are taught in WO 03/040442, the entire contents of which are hereby incorporated by reference.

  Of particular interest for use in the present invention are reactor grade PBPE having an MWD of less than 3.5. The term “reactor grade” is as defined in US Pat. No. 6,010,588 and generally refers to polyolefin resins whose molecular weight distribution (MWD) or polydispersity does not change substantially after polymerization. It is intended to represent.

The remaining units of the propylene copolymer are derived from at least one comonomer such as ethylene, C _4-20 α-olefin, C _4-20 diene and styrene compounds, but preferably the comonomer is ethylene and C 4 _4-12 at least one of α-olefins such as 1-hexene or 1-octene. Preferably, the remaining units of the copolymer are derived from ethylene only.

  The amount of comonomer other than ethylene in the propylene-based elastomer or plastomer is at least partially a function of the comonomer and the desired heat of fusion of the copolymer. When the comonomer is ethylene, typically the units derived from that comonomer comprise no more than about 15 weight percent of the copolymer. The minimum amount of units derived from ethylene is typically at least about 3 weight percent, preferably at least about 5 weight percent, more preferably at least about 9 weight percent, based on the weight of the copolymer. When the polymer includes at least one other comonomer other than ethylene, the preferred composition has a heat of fusion in a propylene-ethylene copolymer with about 3 to 20 weight percent ethylene. While not intending to be bound by theory, in order to achieve similar functionality of those polymers in nonwovens, it is necessary to obtain approximately similar crystallinity and crystal morphology.

  The propylene-based elastomers or plastomers of the present invention may be made by any process and are also Ziegler-Natta catalysis, CGC catalysis, metallocene catalysis, and nonmetallocene metal-centered heteroaryls Copolymers made by ligand catalysis can be included. These copolymers include random copolymers, block copolymers and graft copolymers, but preferably these copolymers are random structured copolymers. Illustrative propylene copolymers include Exxon-Mobil's VISTAMAXX polymer, and propylene / ethylene elastomers and plastomers from The Dow Chemical Company.

The density of the propylene-based elastomers or plastomers of the present invention is typically at least about 0.850 grams per cubic centimeter (g / cm < ³ >), as measured by ASTM D-792, and is at least about 0.000. 860 (g / cm ³ ) and at least about 0.865 (g / cm ³ ).

Propylene based elastomers or weight-average molecular weight plastomers of this invention (Mw) of may vary, but typically, the only restriction is set by considerations practical for (minimum or maximum M _w of (Under the understanding) between 10,000 and 1,000,000. For homopolymers and copolymers used in the production of meltblown fabrics, preferably the minimum Mw is about 20,000, more preferably about 25,000.

The polydispersity of the propylene-based elastomers or plastomers of the present invention is typically between 2 and 3.5. "Narrow polydispersity", "narrow molecular weight distribution", "narrow MWD" and similar terms, weight average molecular weight (M _w) and number average molecular weight (M _n) and the ratio of (M _w / M _n) of about Means less than 3.5, the ratio may be less than about 3.0, may be less than about 2.8, may be less than about 2.5, .3 may be sufficient. Polymers for use in fiber applications typically have a narrow polydispersity. A blend comprising two or more polymers of the present invention, or a blend comprising at least one copolymer of the present invention and at least one other polymer, in view of spinning, is more than It may be dispersible and the polydispersity of such blends is more preferably between 2 and 4.

PBPE for use in the present invention ideally has an MFR from 20 g / 10 min to 5000 g / 10 min, alternatively 2000 g / 10 min. The MFR for copolymers of propylene and ethylene and / or one or more C ₄ -C ₂₀ α-olefins is measured according to ASTM D-1238, Condition L (2.16 kg, 230 ° C.).
MFRs greater than about 250 have the following correlation equation:
MFR = 9 × 10 ¹⁸ Mw ^-3.3584
Estimated by

  Mw (grams per mole) was measured using gel permeation chromatography.

  These PBPEs can advantageously be subjected to the action of chemically induced chain scissors. Such materials are known to increase the MFR of their polymers and reduce their molecular weight distribution (MWD), thereby improving performance in the meltblown process. Generally, reactor grade PBPE preferably has an MFR between 1 g / 10 min and 100 g / 10 min, while after chain scission (if present), the PBPE is preferably 50 g / 10 min. It has an MFR from min to 5000 g / 10 min. Suitable chain scissors include peroxide type and non-peroxide type free radical initiators. For many applications, non-peroxide type chain scissors are preferred, such as cyclic and open chain hydroxylamine esters. One particularly preferred chain scissor is a group of compounds known as hydroxylamine esters (US2003 / 0216494 A1, incorporated herein by reference). This peroxide process has been reported to suffer from various problems such as discoloration, odor or fuming, and these problems can be reduced by using non-peroxide type chain scissors. Furthermore, the use of hydroxylamine esters has also been observed to increase long-term thermal and light stability. In some applications, it may be desirable to use chain scissors in combination with more than one type of chain scissors, such as peroxides or free radical agents.

In one preferred embodiment of the invention, the propylene-based elastomers or plastomers are further characterized by having at least one of the following properties: (I) a ¹³ C NMR peak corresponding to a regio-error at about 14.6 ppm and about 15.7 ppm, with a peak of approximately equivalent intensity, (ii) the amount of comonomer in the copolymer, DSC curves with T _me and T _max decreasing substantially as units derived from ethylene and / or unsaturated comonomers increase, and (iii) when the sample is slowly cooled And X-ray diffraction patterns reporting more gamma crystals than similar copolymers prepared using Ziegler-Natta (ZN) catalysts. Typically, the copolymer of this embodiment is characterized by at least two, preferably all three of these properties. In other embodiments of the invention, these copolymers are further characterized by having one or both of the following properties: (iv) by the method of Koenig (described below) When measured, its comonomer content, ie, a B value greater than about 1.03 when the unit derived from a comonomer other than propylene is at least about 3 weight percent, and (v) from about -1.20 A large skewness index S _ix . Each of these properties and their individual measurements are described in USSN 10 / 139,786 (WO 2/003040442), filed May 5, 2002, as supplemented below (by reference). (Incorporated herein).

B value "High B value" and similar terms are used to describe the polymer chain in a non-random manner, where the ethylene unit of a copolymer consisting of propylene and ethylene, or the ethylene unit of a copolymer consisting of propylene, ethylene and at least one unsaturated comonomer. It means that it is distributed across. The B value ranges from 0 to 2. The higher the B value, the higher the alternating comonomer distribution in the copolymer. The lower the B value, the more block or block comonomer distribution in the copolymer. High B values for polymers made using nonmetallocene based metal-centered heteroaryl ligand catalysts, such as those described in US Patent Application No. 2003/0204017 A1, are obtained by the method of Koenig's method (Spectroscopy of Polymers). American Chemical Society, Washington, DC, 1992), typically at least about 1.03, preferably at least about 1.04, more preferably at least about 1.05, and , In some examples, at least about 1.06. This is very different from the propylene-based copolymers typically produced using metallocene catalysts, such propylene-based copolymers generally exhibit a B value of less than 1.00 and are typically Exhibits a B value of less than 0.95. There are several ways to calculate the B value; the method described below is described by Koenig, J. et al. L. Where a B value of 1 indicates that the comonomer units are completely randomly distributed. The B value described by Koenig is calculated as follows.

B is for propylene / ethylene copolymer
B = [f (EP + PE)] / (2 · F _E · F _P )
Where f (EP + PE) = sum of the diad fractions of EP and PE; and Fe and Fp = the molar fractions of ethylene and propylene in the copolymer, respectively. This diad fraction can be derived from triad data by f (EP + PE) = [EPE] + [EPP + PPE] / 2 + [PEP] + [EEP + PEE] / 2; These B values can be calculated for other copolymers in a similar manner, depending on the diad assignment of each copolymer. For example, the calculation of the B value for a propylene / 1-octene copolymer is:
B = [f (OP + PO)] / (2 · F _O · F _P )
Is used.

  For propylene polymers made with metallocene catalysts, the B value is typically between 0.8 and 0.95. In contrast, propylene polymers produced using activated nonmetallocene based metal-centered heteroaryl ligand catalysts (as described below) have B values of about 1.03 or greater. Yes, typically between 1.04 and 1.08. In other words, for any propylene-ethylene copolymer made using such a nonmetallocene metal-centered heteroaryl catalyst, the propylene block length is relatively high for a given percentage of ethylene. Not only is it short, but as long as the ethylene content of the polymer is very high, there will be very little if any of the long sequences of three or more sequential ethylene insertions present in the copolymer. I mean.

¹³ C NMR
Propylene ethylene copolymers suitable for use in the present invention typically have a substantially isotactic propylene sequence. “Substantially isotactic propylene sequences” and similar terms have isotactic triads (mm) greater than about 0.85, as measured by ¹³ C NMR, preferably Meaning having an isotactic triad (mm) of about 0.90 or greater, more preferably about 0.92 or greater, and most preferably about 0.93 or greater. Isotactic triads are well known in the art and are described, for example, in USP 5,504,172 and WO 00/01745, which patents are isotopic in terms of triad units in the molecular chain of a copolymer as determined by ¹³ C NMR spectra. Mentions tactic sequences. The NMR spectrum is determined as follows.

¹³ C NMR spectroscopy is one of many techniques known in the art for measuring comonomer incorporation into polymers. An example of this technique is the measurement of comonomer content for ethylene / α-olefin copolymers in the Randall literature (Journal of Macromolecular Science, Reviews in Macromolecular Chemistry and Physics, C29 (2 & 3), 201-317 (1989)). Has been described. The basic procedure for measuring the comonomer content of an olefin intercopolymer is that a ¹³ C NMR spectrum under conditions where the intensity of peaks corresponding to different carbons in the sample is directly proportional to the total number of contributing nuclei in the sample. Including as a requirement. Methods for ascertaining this proportionality are known in the art and include allowing sufficient time for post-pulse relaxation, gated decoupling methods and the use of relaxation agents. The relative intensity of a peak or a group of peaks is actually obtained from a computer generated integral of the peaks. After obtaining the spectrum and integrating the peaks, the peak associated with that comonomer is assigned. This assignment can be made by reference to known spectra or literature, or by synthesis and analysis of model compounds, or by using isotope-labeled comonomers. The mole percent of comonomer can be determined by the ratio of the integral corresponding to the number of moles of comonomer and the integral corresponding to the number of moles of all monomers in the interpolymer, for example as described in the Randall literature. .

Data is collected using a Varian UNITY Plus 400 MHz NMR spectrometer, corresponding to a ¹³ C resonance frequency of 100.4 MHz. Acquisition parameters are selected to ensure quantitative ¹³ C data acquisition in the presence of the relaxation agent. Data, while heating the probe head to 130 ° C., ¹ H decoupling gated, 4000 transients per data file, a pulse repetition delay time of 7 seconds, spectral width and 32K data points 24,200Hz Is obtained using the file size. Samples are added to 0.4 g sample in a 10 mm NMR tube with about 3 mL of a 50/50 mixture of tetrachloroethane-d2 / orthodichlorobenzene that is 0.025 M in chromium acetylacetonate (relaxation agent). It is prepared by. The head space of the tube is purged with oxygen by replacing it with pure nitrogen. The sample is dissolved and homogenized by heating the tube and its contents to 150 ° C. with periodic reflux initiated by a heat gun.

  After data collection, their chemical shift is internally referenced to mmmm pentad at 21.90 ppm. Isotacticity at the triad level (mm) includes mm triad (22.5 ppm to 21.28 ppm), mr triad (21.28 to 20.40 ppm) and rr triad (20.67 to 19.4 ppm). Is determined from the integral of the methyl represented. The percentage of mm stereoregularity is determined by dividing the strength of the mm triad by the sum of the mm, mr and rr triads. In the case of propylene-ethylene copolymers made using a catalyst system, such as a nonmetallocene based metal-centered heteroaryl ligand catalyst (as described above), the mr region is from PPQ and PPE. Corrections for ethylene and regio errors were made by subtracting the contribution. In the case of propylene-ethylene copolymers, the rr zone was corrected for ethylene and regio errors by subtracting contributions from PQE and EPE. In the case of copolymers with other monomers that give peaks in the mm, mr and rr areas, the integration for these areas subtracts the interference peaks using standard NMR techniques after those peaks have been identified. As a result, the same correction was made. This can be accomplished, for example, by analyzing a series of copolymers consisting of varying levels of monomer incorporation, by literature assignments, by isotopic labeling, or by other means known in the art.

Regioerrors at about 14.6 ppm and about 15.7 ppm for non-metallocene based metal-centered heteroaryl ligand catalysts, such as those prepared using the catalysts described in US 2003/0204017 The ¹³ C NMR peak corresponding to is believed to be the result of a stereoselective 2,1-insertion error of the propylene unit into the growing polymer chain. In general, for a given comonomer content, the higher the level of regioerror, the lower the melting point and modulus of the polymer, while the lower the level, the melting point and elasticity of the polymer. The rate increases accordingly.

Konig, J.H. L. Matrix method for calculating the B value according to For propylene / ethylene copolymers, the following procedure can be used to determine the composition and sequence distribution of the comonomer. Integration areas are determined from the ¹³ C NMR spectrum and input into the matrix calculation to determine the molar fraction of each triad sequence. The matrix assignment is then used with these integrals to calculate the mole fraction of each triad. This matrix calculation is based on Randall's method modified to include additional peaks and sequences for 2,1 regio errors (Journal of Macromolecular Chemistry and Physics, Reviews in Macromolecular Chemistry and Physics, C29 (2 & 3), 201- 317 (1989))). Table A shows the integration area and triad designation used in the assignment matrix. The number associated with each carbon indicates the region of the spectrum that resonates.

Mathematically, the matrix method is a vector equation s = fM, where M is an assignment matrix, s is a spectral row vector, and f is a mole fraction composition vector. Successful execution of the matrix method requires the resulting equation to be determined or over-determined (the number of independent equations equal to or greater than the number of variables) and a solution to that equation is needed to compute the desired structural information It is necessary to define M, f and s so as to include various molecular information. The first step in this matrix method is to determine the elements in the composition vector f. These elements of this vector should be the molecular parameters selected to provide structural information about the system under investigation. For copolymers, a reasonable set of parameters is any odd n-ad distribution. Usually, the triad distribution is most often used in this composition vector f because the peaks obtained from the individual triads are reasonably well resolved and easy to assign. Triads for E / P copolymers are EEE, EEP, PEE, PEP, PPP, PPE, EPP and EPE. In the case of reasonably high molecular weight (> = 10,000 g / mol) polymer chains, this ¹³ C NMR experimental apparatus cannot distinguish between EEP and PEE or PPE and EPP. Since all Markovian E / P copolymers have PEE and EPP mole fractions equal to each other, an equality restriction was also chosen in this run. The same treatment was performed for PPE and EPP. The two equivalence limits described above reduce 8 triads to 6 independent variables. For clarity, this composition vector f is still represented by all eight triads. These equivalence restrictions are implemented as internal restrictions when solving the matrix. The second step in the matrix method is to determine the spectral vector s. Usually the elements of this vector are a well-defined integration area in the spectrum. In order to guarantee the determined system, the number of integrals needs to be as large as the number of independent variables. The third step is to determine the allocation matrix M. This matrix is constructed by finding the carbon contribution of the central monomer unit in each triad (column) for each integration zone (row). When determining which carbon belongs to the central unit, it is necessary to be consistent with respect to the direction of propagation of the polymer. A useful property of this assignment matrix is that the sum of each row is equal to the number of carbons in the central unit of the triad that is the contributing factor of that row. This equivalence can be easily checked, and therefore some common data entry errors can be prevented.

  After building the allocation matrix, a redundancy check needs to be performed. In other words, the number of linear independent columns needs to be equal to or greater than the number of independent variables in the product vector. If the matrix fails the redundancy test, it is necessary to return to the second step to re-partition the integration region and redefine the assignment matrix until it passes the redundancy test.

  In general, when the number of columns plus the number of additional limiting or constraint elements is greater than the number of rows in the matrix M, the system is overdetermined. The greater this difference, the more the system is overdetermined. The higher the system is overdetermined, the more the matrix method corrects for mismatched data that can result from low signal-to-noise (S / N) ratio data or partial saturation of some resonances. Can be identified.

  The last step is to solve the matrix. This can be easily done with Microsoft Excel by using the solver function. This solver first estimates the solution vector (molar ratio between various different triads) and then iterates to minimize the sum of the differences between the calculated product vector and the input product vector s It works by estimating automatically. The solver can also specify one input restriction element or constraint element.

Table A. The contribution of each carbon in the central unit of each triad to various different integration regions. P = propylene, E = ethylene, Q = 2,1 inserted propylene.

  The composition of 1,2-inserted propylene is calculated by summing the mole fractions of all stereoregular propylene centered triad sequences. The 2,1-inserted propylene composition (Q) is calculated by summing the mole fractions of all Q-centered triad sequences. The mole percent is calculated by multiplying the mole fraction by 100. The composition of C2 is determined by subtracting the mole percentage values of P and Q from 100.

DSC Method Differential Scanning Calorimetry (DSC) is a common technique that can be used to examine the melting and crystallization of semi-crystalline polymers. The general principles of DSC measurements and the application of DSC to the study of semicrystalline polymers are described in standard texts (eg, “Thermal Characterization of Polymeric Materials” edited by EA Turri, Academic Press, 1981). Has been. The particular copolymer used in the practice of this invention is characterized by a DSC curve with a T _{me that} remains essentially the same and a decreasing T _max as the amount of unsaturated comonomer in the copolymer increases. T _me means the temperature at which melting ends. T _max means the peak melting temperature.

  Differential scanning calorimetry (DSC) analysis is performed by TA Instruments, Inc. Determined using the model Q1000 DSC available from DSC calibration is performed as follows. First, a baseline is obtained by performing a DSC from −90 ° C. to 290 ° C. without any sample in the aluminum DSC pan. Then 7 milligrams of fresh indium sample was heated to 180 ° C. and after cooling the sample to 140 ° C. at a cooling rate of 10 ° C./min, the sample was held isothermally at 140 ° C. for 1 minute. And subsequently analyzed by heating the sample from 140 ° C. to 180 ° C. at a heating rate of 10 ° C./min. The heat of fusion and the onset of melting of this indium sample is determined and is in the range of 156.6 ° C. to 0.5 ° C. for the onset of melting and 28.71 J / g to 0.5 J / g for the heat of fusion. It is checked that it is within range. The deionized water is then analyzed by cooling a sample of fresh droplets in the DSC pan from 25 ° C to -30 ° C at a cooling rate of 10 ° C / min. The sample is held isothermally at −30 ° C. for 2 minutes and heated to 30 ° C. at a heating rate of 10 ° C./min. The onset of melting is determined and checked to be in the range of 0 ° C. to 0.5 degrees.

  The propylene sample is pressed into a thin film at a temperature of 190 ° C. Approximately 5 to 8 mg of sample is weighed and placed in a DSC pan. Press the lid onto the pan to ensure a sealed atmosphere. The sample pan is placed in a DSC cell and heated at a high rate of about 100 ° C./min to a temperature above the melting temperature of about 60 ° C. The sample is held at this temperature for about 3 minutes. The sample is then cooled to −40 ° C. at a rate of 10 ° C./min and held isothermally at that temperature for 3 minutes. The sample is then heated at a rate of 10 ° C./min until completely melted. The resulting enthalpy curve is analyzed for peak melting temperature, crystallization onset and peak crystallization temperature, heat of fusion and heat of crystallization, and any other interesting DSC analysis items.

  Mechanical testing was performed using an Instron (model 5564) with a 100N load cell, provided by Instron Corporation (Norwood, Mass.). This device was used in the tensile test and the 50 percent hysteresis test described below.

Skewness index The skewness index is calculated from data obtained by temperature rising elution fractionation (TREF). This data is expressed as a normalized plot of weight fraction as a function of elution temperature. The separation mechanism is similar to that of copolymers of ethylene, where the molar content of the crystallizable component (ethylene) is the main factor determining the elution temperature. In the case of copolymers of propylene, mainly the molar content of isotactic propylene units determines the elution temperature.

値Ｔ_maxは、このＴＲＥＦ曲線における５０℃から９０℃までの間で最大の重量分率を溶出する温度として定義される。Ｔ_iおよびｗ_iは、ＴＲＥＦ分布における任意なｉ番目の画分の、それぞれ、溶出温度および重量分率である。これらの分布は、３０℃より高い温度で溶出するこの曲線の全領域に関して正規化されている（ｗ_iの総和が１００パーセントになる）。従って、この指数は、結晶化されたポリマーの形のみを反映する。結晶化されていないあらゆるポリマー（３０℃またはそれ以下の温度で溶液のままであるポリマー）は、式１に示されている計算から除外されている。 The shape of the metallocene curve results from random incorporation of the inherent comonomer. A prominent feature of this curve shape is tailing at lower temperatures compared to the sharpness or steepness of the curve at higher elution temperatures. A statistic that reflects this type of asymmetry is skewness. The following equation represents the skewness index S _ix as a measure of this asymmetry.

The value T _max is defined as the temperature that elutes the maximum weight fraction between 50 ° C. and 90 ° C. in this TREF curve. T _i and w _i are the elution temperature and the weight fraction, respectively, of any i-th fraction in the TREF distribution. These distributions are normalized for the entire area of this curve eluting at temperatures above 30 ° C. (the sum of w _i is 100 percent). Therefore, this index reflects only the shape of the crystallized polymer. Any polymer that has not crystallized (a polymer that remains in solution at a temperature of 30 ° C. or below) is excluded from the calculation shown in Equation 1.

Gel Permeation Chromatography The molecular weight distribution of these polymers was determined by gel permeation chromatography (GPC) on a Polymer Laboratories PL-GPC-220 high temperature chromatograph equipped with four linear mixed bed columns (Polymer Laboratories (particle size 20 microns)). ). The oven temperature is 160 ° C. with an autosampler hot zone of 160 ° C. and a warm zone of 145 ° C. The solvent is 1,2,4-trichlorobenzene containing 200 ppm 2,6-di-t-butyl-4-methylphenol. The flow rate is 1.0 ml / min and the injection volume is 100 microliters. About 0.2 weight percent of the sample solution for injection was prepared by placing the sample in nitrogen purged 1,2,4-trichlorobenzene containing 200 ppm 2,6-di-tert-butyl-4-methylphenol. Prepare by dissolving for 2.5 hours at 160 ° C. with gentle mixing.

Molecular weights are determined by using 10 narrow molecular weight distribution polystyrene standards (EasiCal PS1 in the range of 580-7,500,000 g / mol available from Polymer Laboratories) along with their elution volumes. Presumed. These equivalent polypropylene molecular weights are given by the Mark-Houwink equation:
{N} = KM ^a
[Wherein K _pp = 1.90E-04, a _pp = 0.725 and K _ps = 1.26E-04, a _ps = 0.702], polypropylene (Th. G. Scholte, NL As described in J. Appl. Polym. Sci., 29, 3763-3782 (1984) by J. Meijerink, HM Schoffeleers and AMG Brands and polystyrene (E.P. Determined by using the appropriate Mark-Houwink coefficient for Macromolecules, 4, 507 (1971) by Otokka, RJ Roe, NY Hellman, PM Muglia. .

  The meltblown fabrics of the present invention can be made of 100 percent PBPE or can be blended with other polymers to form the fibers used to make the fabric. Suitable polymers for blending with these PBPEs are commercially available from a variety of suppliers, including but not limited to other polyolefins such as ethylene polymers (eg, low density polyethylene ( LDPE), ULDPE, medium density polyethylene (MDPE), LLDPE, HDPE, uniformly branched linear ethylene polymer, substantially linear ethylene polymer, graft modified ethylene polymer, ethylene-styrene interpolymer (ESI), ethylene vinyl Acetate interpolymer, ethylene acrylic acid interpolymer, ethylene ethyl acetate interpolymer, ethylene methacrylic acid interpolymer, ethylene methacrylate ionomer, etc.), polycarbonate, polystyrene, conventional polyp Pyrene (eg, homopolymer polypropylene, polypropylene copolymer, random block polypropylene interpolymer, etc.), thermoplastic polyurethane, polyamide, polylactic acid interpolymer, thermoplastic block polymer (eg, styrene butadiene copolymer, styrene butadiene styrene triblock copolymer, styrene ethylene Butylene styrene triblock copolymer, etc.), polyether block copolymer (eg, PEBAX), copolyester polymer, polyester / polyether block copolymer (eg, HYTEL), ethylene carbon monoxide interpolymer (eg, ethylene / carbon monoxide (ECO)) ), Copolymer, ethylene / acrylic acid / carbon monoxide (EAACO) terpolymer, ethylene / Tacrylic acid / carbon monoxide (EMAACO) terpolymer, ethylene / vinyl acetate / carbon monoxide (EVACO) terpolymer and styrene / carbon monoxide (SCO)), polyethylene terephthalate (PET), chlorinated polyethylene, and the like, and Including mixtures thereof. When the PBPE (or blend of PBPE) used to make the meltblown fabric of the present invention is blended with one or more other polymers, the PBPE is preferably the sum of the blends Of the weight, it comprises at least about 90 weight percent, more preferably at least about 92 weight percent, more preferably at least about 94 weight percent, more preferably at least about 96 weight percent.

  It is also readily recognized that other additives may be added as is generally known in the art. Examples of such additives are antioxidants, UV stabilizers, heat stabilizers, slip agents, pigments or colorants, processing aids (such as fluoropolymers), crosslinking catalysts, flame retardants, fillers, foaming agents. Etc.

  It has been observed that meltblown fabrics containing more than about 9 percent by weight of ethylene tend to stick to collection drums or belts and are difficult to remove, so the present PBPE used to produce meltblown fabrics Slip agents or antistatic agents can be particularly beneficial when they contain more than about 9 weight percent ethylene. Typical slip agents include oleamide, erucamide or stearamide, and a typical antistatic agent is glycerol monostearate (GMS).

  The meltblown fabric can be manufactured in any manner known in the art. Typical processes include, but are not limited to, Exxon single row lines, multiple row Biax-Fiberfilm and Hills type lines. Non-woven process descriptions are described in individual companies' respective fields and in publications such as The Nonwovens Handbook, Association of Nonwovens Fabrics Industry, Cary NC and Principles of Nonwovens, INDA, Cary NC, etc. . U.S. Pat. No. 3,849,241 also describes a suitable meltblown process. These references are hereby incorporated by reference.

The meltblown fabric of the present invention has a stretch rate (expressed in percent (elong (percent))) between 20 percent and 675 percent per inch width (normalized to 20 gsm) Has a tensile strength (F _MD ) greater than about [−0.00143 × elongation (percent) +0.823] and greater than about 0.1 lb when the elongation is 675 percent or more. Have

Tensile strength is the peak force on a basis normalized to 20 gsm. This is the following formula:
F _MD = F peak, _MD × (20 / BasisWt (gsm))
Where F peak and _MD are gripped by the line contact grip with a spacing of 3 inches, 1 inch wide and 6 inches long cut parallel to the flow direction. The peak force measured on the strip. The sample is pulled until it breaks at a rate of 10 inches per minute. The resulting _FMD is measured in pounds per inch wide. BasisWt is the basis weight of the nonwoven fabric measured in grams per square meter. Basis weight is measured for each sample by weighing a 1 inch wide and 6 inch long sample strip with an analytical balance and converting it to grams per square meter. Care must be taken not to sample from the edges and defects present in the web. Defects include holes, uneven portions, and fiber agglomeration.

More preferably, the meltblown fabric of the present invention has a strain elongation of 20 percent to 675 percent and is greater than [−0.00143 × elongation (percent) +1] per inch width (normalized to 20 gsm). Tensile strength, even more preferably greater than [−0.00143 × elongation (percent) +1.2]. The elongation rate is given by the following formula:
Elongation rate (%) = [(L peak force−L ₀ ) / L ₀ ] × 100%
(Where L ₀ is the initial length of 3 inches, and the L peak force is the length corresponding to the strain at the F peak and _MD ). Strain is defined as the change in percent of the sample length.
Strain (%) = [(L−L ₀ ) / L ₀ ] × 100%
Where L is the length of the sample.

  The meltblown fabrics of the present invention also preferably have an immediate set of about 35 percent or less, more preferably about 12 percent or less, as measured by a 50 percent hysteresis test. Have The 50 percent hysteresis test is performed as follows. A strip that is 1 inch wide and 6 inches long, cut parallel to the flow direction, is gripped with a contact grip on the line spaced 3 inches apart. The sample is pulled to a strain of 50 percent strain at a speed of 10 inches per minute. Then immediately return the crosshead to 0 percent strain at the same speed. The crosshead is then stretched again at the same speed immediately until a positive tension is measured. This point is defined as permanent strain. The strain corresponding to the expression of the positive force is set as the immediately set strain.

  Further, the meltblown fabrics of the present invention preferably have a retained load of about 0 percent or more, even more preferably about 20 percent or more, as measured by a 50 percent hysteresis test. Have a load. Residual load is measured by dividing the force at 30 percent strain during contraction by the force at 30 percent strain during initial extension. Residual load is the ratio multiplied by 100 percent.

Hydrohead Hydrohead is a measure according to the EDANA test method: WSP 80.6 (05). This test method applies to nonwoven fabrics intended to be used as a barrier against fluid penetration. This hydrostatic pressure test measures the resistance of a nonwoven fabric to penetration of water under various hydraulic head pressures.

  A non-woven fabric is placed on the test head container to form a cover. A standardized water pressure is applied to the sample at a constant rate until a leak appears on the outer surface of the nonwoven. The test result in this hydrostatic pressure test is measured at the point where the first droplet appears in three separate areas on the sample. Results are reported in either centimeters / minute or millibars / minute.

Preferred meltblown nonwoven, basis weight of 25 gsm, up to 10 cm H ₂ O / min 80 cm H ₂ O / min, preferably has a hydrohead performance of up to 20 cm H ₂ O / min 80 cm H ₂ O / min. The higher the basis weight, the higher the hydrohead performance can be achieved.

Laminate Structure In many applications, meltblown fabrics, such as the meltblown fabrics of the present invention, can be improved by combining the meltblown fabric with one or more additional fabric layers that are bonded together. Such structures can be represented by letters representing various layers, such as SM in a two-layer structure consisting of a spunbond layer and a meltblown layer, SMS in a three-layer structure, or more generally an SM _x S structure (x is a meltblown layer). It is often identified by the number of layers). Laminate structures, particularly laminate structures comprising the meltblown layer described above, are another aspect of the present invention.

  The nonwoven laminate of the present invention comprises at least two nonwoven layers. Preferably, at least one of these nonwoven layers is manufactured using a meltblown process and at least one of these nonwoven layers is manufactured using a spunbond process. The nonwoven laminates of the present invention are characterized by the combined properties of overall structural softness and bond strength between their layers.

The bending modulus is determined according to ASTM D 5732-95. Preferred nonwoven laminates of the present invention have a normalized basis weight of 20 gsm and an overall normalized bending modulus (E _{bend, MD} , _{20 gsm} ) of less than 0.06 mN · cm, more preferably 0. 0.04 mN · cm, most preferably less than 0.03 mN · cm E- _{bend, MD} , _{20 gsm} . This EE _{bend, MD} , _20gsm is the following formula:
E _{bend, MD, 20 gsm} = E _{bend, MD × (20 / BasisWt (} gsm))
Where E _{bending and MD} are the bending coefficients when measuring the bending coefficient, and BasisWt is the basis weight of the fabric measured in grams per square meter.

  Preferred nonwoven laminates also exhibit a peel strength greater than about 2 N / 5 cm between these nonwoven layers, more preferably greater than about 2.5 N / 5 cm, and most preferably greater than about 3 N / 5 cm. Exhibits peel strength. Peel strength is determined by the maximum force at N required to pull two or more substrates apart from each other using a sample having a width of 5 cm.

  These two nonwoven layers can be any polymer that can form a nonwoven laminate structure having an overall flexural modulus of about 0.005 N · mm or less and a peel strength between the nonwoven layers of at least about 2 N / 5 cm. Or it may be made of a polymer blend. In general, it is preferred that at least one nonwoven layer is a meltblown layer, and it is particularly preferred that the nonwoven layer be a meltblown nonwoven as described above. Other meltblown fabrics that may be suitable for these novel laminates include, but are not limited to, meltblown fabrics described in US2005 / 0106978 and WO2005 / 052052.

  In general, it is preferred that at least one of these layers is a spunbond layer, which is made of fibers comprising a polyethylene material. The fiber may be a monofilament or a composite fiber. Bicomponent fibers include all known configurations, including sheath-core configurations, side-by-side configurations and island-like configurations at sea. Seascore fiber is a preferred composite fiber configuration.

The spunbond fibers may be made from any suitable material. Particular embodiments include propylene based polymers, blends containing propylene based polymers, ethylene based polymers, blends containing ethylene based polymers, and blends of the foregoing. Sometimes improved softness is required. Embodiments meeting this need are described in recently filed US applications 11/083891 and 11/0668098, both of which are hereby incorporated by reference in their entirety. A spunbond fabric, and a spunbond fiber comprising a polyethylene material, particularly a spunbond fiber wherein the polyethylene material comprises at least a portion of the surface of the fiber. The term “polyethylene material” is intended to include any polymer containing more than 50 mole percent ethylene. Often, the polymer comprises a alpha-olefin copolymers, typically copolymers thereof are C ₃ -C ₂₀ alpha-olefin. Hexene and octene are preferred copolymers. The polyethylene material may be produced by any type of reactor or reactor configuration known in the art by gas phase polymerization, liquid phase polymerization or slurry polymerization, or any combination of the foregoing polymerization methods.

  “Polyethylene material” refers to many types of materials known in the art, such as materials known as low density polyethylene (LDPE), high density polyethylene (HDPE) and linear low density polyethylene (LLDPE), as well as such materials. Including blends and the like. A particularly useful polyethylene material for use in the spunbond material of the present invention is an LLDPE material. This is substantially defined in US Pat. No. 5,272,236, US Pat. No. 5,278,272, US Pat. No. 5,582,923, and US Pat. No. 5,733,155. Linear ethylene polymer; homogeneously branched linear ethylene polymer composition, such as the ethylene polymer composition of US Pat. No. 3,645,992; heterogeneously branched ethylene polymer, such as US Pat. No. 4,076 And ethylene polymers prepared by the process disclosed in US Pat. No. 6,698, and / or blends of those polymers (eg, blends disclosed in US Pat. No. 3,914,342 or US Pat. No. 5,854,045). Each of these references is incorporated herein by reference.

The presently preferred laminated structure, at a basis weight of 25 gsm, from 100 mm H ₂ O to 800 mm H ₂ O, preferably have a hydrohead performance from 200 mm H ₂ O to 800 mm H ₂ O. The higher the basis weight, the higher the hydrohead performance can be achieved.

Additional Measurement Methods Unless otherwise indicated, the following analytical techniques are used to characterize the materials considered in this application.

Density Method Coupon samples (1 inch × 1 inch × 0.125 inch) were compression molded at 190 ° C. according to ASTM D4703-00 and cooled using Procedure B. After the sample cooled to 40-50 ° C, the sample was removed. After the sample reached 23 ° C., the dry weight of the sample and the weight in isopropanol were weighed using an Ohus AP210 balance (Ohaus Corporation, Pine Brook, NJ). Density was calculated as indicated in ASTM D792 Procedure B.

Tensile test A 1 inch wide and 6 inch long strip cut parallel to the flow direction is gripped by a line contact grip with a 3 inch spacing. This flat grip facing is covered with rubber. The pressure is adjusted (usually 50-100 psi) to prevent slipping. Raise the crosshead at a rate of 10 inches per minute until the sample breaks. The strain is calculated by dividing the displacement of the crosshead by 3 inches and multiplying by 100. The load is equal to pounds force per inch of width.

The tensile strength is the following formula:
F _MD = F peak, _MD × (20 / BasisWt (gsm))
Where F peak, _MD is the peak force measured according to the method described above, and BasisWt is the basis weight of the nonwoven fabric measured in grams per square meter. The elongation rate is given by the following formula:
Elongation rate (%) = [(L peak force−L ₀ ) / L ₀ ] × 100%
(Where L ₀ is the initial length of 3 inches, and the L peak force is the length corresponding to the strain at the F peak and _MD ).

Scanning Electron Microscopy A sample for scanning electron microscopy was placed on an aluminum sample stage using a carbon black filled tape and a copper filled tape. The mounted samples were then used using an SPI-Module Sputter Coater (model number 11430) available from Structure Probe Incorporated (West Chest, Massachusetts) fitted with an argon gas supply and a vacuum pump. 100-200 kg of gold was coated.

  These gold-coated samples were then examined on a Hitachi S4100 scanning electron microscope equipped with a field effect gun, supplied by Hitachi America, Ltd. (Shaumberg, Illinois). Samples were examined in secondary electron imaging mode, measured using an acceleration voltage of 3-5 kV, and data collected using a digital image acquisition system.

  The fiber diameter was measured by acquiring images of the fabric at at least three different locations. At least 15 fiber diameters were measured from these images using ImagePro Express image analysis software (Media Cybernetics, Sever Spring MD). Do not measure the same fiber more than once, and measure the value of “married” or “roped” filaments (fibers that are widely bonded along the fiber axis). Care was taken not to include it. Thereafter, an average value and a standard deviation of these fiber diameters were calculated.

Specific embodiments The effect of spinning conditions was investigated with these polymers using 25-38 MFR. The elongation stress achieved by adjusting the throughput and take-off speed determined the amount of stress-induced crystallinity in the fiber and thus the resulting mechanical properties. The greater the elongation stress achieved at a drawdown greater than 1000, the higher the crystallinity, and thus the higher the stiffness. At lower crystallinity or drawdown less than 1000, more elasticity was preserved. In the case of more elastic fibers, a very low crystallinity or a drawdown of less than 500 was preferred. In order to confirm that the elasticity was maintained, the tensile hysteresis behavior was measured.

これらの樹脂の特性が表２に記載されている。

密度はＡＳＴＭ Ｄ−７９２により測定された。エチレン含有量は、先に説明されているＮＭＲ法を用いて測定された。分子量分布（ＭＷＤ）は、上で説明されているＧＰＣ法を用いて測定された。メルトフローレート（ＭＦＲ）は、ＡＳＴＭ Ｄ−１２３８の条件Ｌ（２．１６ｋｇ、２３０℃）により測定された。 Various different resins used are presented in Tables 1 and 2. The process conditions used to synthesize propylene-ethylene resins A, B, C and D are shown in Table 1.

The properties of these resins are listed in Table 2.

Density was measured according to ASTM D-792. The ethylene content was measured using the NMR method described above. The molecular weight distribution (MWD) was measured using the GPC method described above. Melt flow rate (MFR) was measured according to ASTM D-1238, Condition L (2.16 kg, 230 ° C.).

  Propylene-ethylene copolymers containing 4.5 to 12.0 weight percent ethylene were used. For comparison, ethylene-octene copolymers and polypropylene homopolymers were also used. The melt flow rate (MFR) of the propylene-ethylene polymer was 25 to 1145 g / 10 min. The melt indexes (MI) of resins K and L based on ethylene were 150 g / 10 min and 500 g / 10 min, respectively.

  Examples of the present invention and comparative examples were produced using a Biax Fiber-Film meltblown line (Greenville, Wisconsin) at various conditions. The spinneret had 128 holes (two rows of 64 hole spinnerets) each having a diameter of 0.014 inches. The length to diameter ratio (L / D) for this 1 inch extruder was 20. Besides the choice of extruder and the choice of mold, the main variables are melt temperature, air pressure, air temperature and throughput (grams / hole / min, i.e. ghm), the throughput being the pump speed, collector drum speed and It was adjusted by the distance (DCD) between the mold and the collector. In addition, selected Examples and Comparative Examples of the present invention were also manufactured on a Hills type meltblown line.

この表記法における文字「ｃ」は比較例を表す。
Ｘは、Ｃｉｂａ Ｓｐｅｃｉａｌｔｙ Ｃｈｅｍｉｃａｌｓから入手可能なＩＲＧＡＴＥＣ ＣＲ７６ポリマー改質剤であり、マスターバッチにおけるヒドロキシルアミンエステルである。
サンプル７−１、８−１および９−１はＨｉｌｌｓ型ラインで製造された。この表における他のすべてのサンプルは、Ｂｉａｘ−Ｆｉｂｅｒｆｉｌｍ Ｃｏｒｐｏｒａｔｉｏｎ（Ｇｒｅｅｎｖｉｌｌｅ、Ｗｉｓｃｏｎｓｉｎ、ＵＳＡ）により製造されたＢｉａｘ ５’’幅メルトブローンラインで作られた。 The conditions used to make the examples and comparative examples of the present invention are shown in Tables 3, 4 and 5. By adjusting the variables described above, the fiber diameter, basis weight and degree of self-bonding were controlled. Samples represented only by numbers and hyphen symbols (ie, 1-1 through 6-4, and 7-1 through 9-1) are examples of the present invention and are notated with the letter “c”. Method samples (ie, 1-1c to 3-3c) are comparative examples.

The letter “c” in this notation represents a comparative example.
X is an IRGATEC CR76 polymer modifier available from Ciba Specialty Chemicals and a hydroxylamine ester in a masterbatch.
Samples 7-1, 8-1 and 9-1 were produced on a Hills type line. All other samples in this table were made with a Biax 5 ″ wide meltblown line manufactured by the Biax-Fibrefilm Corporation (Greenville, Wisconsin, USA).

Fabric samples made to investigate the effects of hydroxylamine masterbatch levels were produced. These fabric samples are listed in Table 4.

Further examples of fabrics produced on the Hills type line are shown in Table 5. It should be noted that the hydrohead performance of these new fabrics is comparable to conventional fabrics based on hPP while providing additional desired bonding performance.

  By plotting the bending modulus against the stretch rate of the fabric described in the previous table (FIG. 1), the difference between the fibers of the present invention and the comparative example is evident. The fibers of the present invention depict regions of higher elongation (greater than about 75 percent) and lower normalized bending modulus (less than 0.6 mN · cm at 20 gsm) as compared to the comparative example. Functionally, this behavior is reflected in fibers that can exhibit better drape characteristics (lower bending modulus) and fibers that can have greater extensibility (higher elongation before failure).

FIG. 2 shows the normalized peak force plotted against elongation to failure. In contrast to the comparative example, the sample of the present invention has the following formula:
a. F _MD ≧ [−0.00143 × elongation (percent) +0.823] (when elongation is from 20 percent strain to 675 percent strain)
b. F _MD ≧ 0.1 lb (when the elongation is 675% strain or more)
Occupies a region of higher peak force and elongation represented by
This result in combination with the result obtained from FIG. 1 shows that the embodiment of the present invention exhibits a new and desired combination characteristic of the following characteristics. Better drape characteristics (lower bending modulus), higher extensibility (higher elongation at peak force) and higher strength (higher normalized peak force).

  There are various modes of elastomer behavior. FIG. 3 shows the set strain plotted against the elongation in the example of the present invention. The PBP-based fabric of the present invention exhibits a set strain of less than about 50 percent strain. If higher elastic performance is required, the selected PBE-based fabric exhibits a more preferred set strain of less than about 15 percent. Thus, selected embodiments of the present invention have been shown to have a lower set strain, which is one aspect of elastomer behavior. Since the comparative hPP examples had an elongation to failure of less than 50 percent strain, these examples failed to survive this test.

  Another aspect of elastomer behavior is the retractive force. Residual load is a measure of contractile force. For a given extension force, the higher the residual load, the higher the contraction force. FIG. 4 shows MD residual load plotted against elongation. PBP-based fabrics have been shown to have a residual load of 0 percent or more. PBE-based fabrics have been shown to have a residual load greater than about 15 percent. PBE-based fabrics have been shown to have a relatively large shrinkage force in their own application, or with other ingredients. Such behavior is reflected in the higher “holding ability” required for improved fit or comfort. In many elastic applications, a higher holding capacity is desirable because of the higher mechanical ability to secure one object to another.

Table 6 summarizes the tensile and elastic properties studied so far.

Based on these findings as described, the following table for the preferred range of fibers of the present invention is set forth in Table 7.

Selected meltblown fabric from Table 5 is selected for production of SMxS laminate structure ("S" represents spunbond layer, "M" represents meltblown layer, "x" represents number of meltblown layers) It is. These meltblown fabrics are combined with various 20 gsm spunbond fabrics (Table 8) manufactured using Reicofil3 technology from Reifenhauser to create SMS and SS laminates (Tables 9 and 10). (21 percent bonding area) was used to point bond at the recommended temperatures for various materials (hPP, PE and composites (bico)).

In all cases, the laminates of the present invention made using the meltblown fabrics of Examples 11-19 had a minimum or equal bending modulus. This indicates that the low flexural modulus of the preferred composition range meltblown fabric resulted in a new laminate. The low bending modulus is reflected in softness and good drape characteristics in the end use.

  Measuring the peel strength of these laminates by cutting a 5 cm wide strip parallel to the flow direction (MD) and peeling at a rate of 100 mm / min in Instron with a 180 ° T-peel shape, It shows that laminates made with meltblown fabric 11-19 consistently exhibit the highest peel strength (FIG. 6). Peel strength is reported in Newtons per 5 cm width.

A closer look, this result is particularly surprising. First, SMS structures made with meltblown fabrics 11-19 exceeded the peel strength of spunbond fabrics against themselves ("Control" in Tables 9 and 10 is indicated as no meltblown layer) In the case of two spunbond layers). Second, SMS structures made with meltblown fabrics 11-19 are hPP spunbond fabrics (12-18 and 12-19) for hPP meltblown layers (11-18c, 11-04c, or 11-07c). Exceeded the peel strength. Typically, the binding of dissimilar materials is relatively weak. As a result, the laminates produced using the meltblown examples 11-19 unexpectedly exhibit high bond strength. Finally, when at least one spunbond includes a polyethylene-based polymer (12-21, 12-22, and 125-23), the peel strength not only exceeds the control meltblown, but also includes an hPP-based meltblown. It also exceeds the laminate (11-18c, 11-04c, or 11-07c). This indicates that the properties of preferred meltblown compositions have been improved, as well as the properties of new laminates containing them.

Figure 5 is a plot of bending modulus versus elongation for the indicated examples and comparative examples. Figure 6 is a plot of peak force versus elongation for the indicated examples and comparative examples. FIG. 4 is a plot of set strain versus elongation for the indicated examples and comparative examples. FIG. 6 is a plot of load retention versus elongation for the indicated examples and comparative examples. It is a bar graph which shows the bending coefficient with respect to the laminated structure as instruct | indicated. It is a bar graph which shows the peeling strength with respect to the laminated structure as instruct | indicated.

Claims (47)

The following formula,
a. F _MD ≧ [−0.00143 × elongation (percent) +0.823] (when the elongation rate is 20% to 675%)
b. F _MD ≧ 0.1 lb (when the elongation is 675 percent or more)
A meltblown fabric having an MD peak tension (F _MD ) normalized to a basis weight of 20 gsm per inch of width, wherein the fabric is derived from at least about 50 weight percent propylene And at least one copolymer with at least about 5 weight percent units derived from a comonomer other than propylene. The said at least one copolymer is characterized by having ¹³ C NMR peaks corresponding to regioerrors at about 14.6 ppm and about 15.7 ppm, and the peaks are of approximately equal intensity. Meltblown fabric as described in   The meltblown fabric of claim 1, wherein the comonomer comprises from 3 weight percent to 20 weight percent ethylene.   The meltblown fabric according to claim 1, wherein the comonomer comprises from 9 weight percent to 20 weight percent ethylene.   The meltblown fabric of claim 1, wherein the copolymer has an MFR of 25 to 5000.   The meltblown fabric according to claim 1, wherein the copolymer is subjected to chemically induced chain scission and has an MFR from 50 to 5000.   The meltblown fabric according to claim 6, wherein the chain scission is caused by combining the composition with a free radical initiator prior to extrusion.   The meltblown fabric according to claim 7, wherein the free radical initiator is of the peroxide type.   The meltblown fabric according to claim 7, wherein the rheology modifier is non-peroxide type.   The meltblown fabric of claim 9, wherein the non-peroxide rheology modifier is a hydroxylamine ester.   The meltblown fabric according to claim 6, wherein the chain scission is caused by combining the composition with at least one peroxide-type and one non-peroxide-type free radical initiator.   The meltblown fabric according to claim 1, wherein the average fiber diameter is less than 10 microns.   The meltblown fabric according to claim 1, having an immediate strain of about 50 percent or less as measured in a 50 percent one cycle test.   The meltblown fabric according to claim 1 having a residual load of about 0 percent or more as measured in a 75 percent one cycle test.   The meltblown fabric according to claim 1, having a residual load of about 15 percent or more as measured in a 75 percent one cycle test.   The meltblown fabric of claim 1, wherein the fabric comprises less than about 10 weight percent hPP and / or RCP.   The meltblown fabric of claim 1, wherein the fabric comprises less than about 8 weight percent hPP and / or RCP.   The meltblown fabric of claim 1, wherein the fabric comprises less than about 6 weight percent hPP and / or RCP.   The meltblown fabric of claim 1, wherein the fabric comprises less than about 4 weight percent hPP and / or RCP.   A nonwoven laminate comprising a meltblown nonwoven layer according to any one of claims 1 to 19 and at least one spunbond nonwoven layer.   21. A nonwoven laminate according to claim 20, wherein the spunbond layer comprises fibers characterized in that a polyethylene-based material comprises at least part of the surface of the fibers.   The nonwoven laminate according to claim 20, wherein the spunbond layer comprises a composite fiber.   23. The nonwoven laminate according to claim 22, wherein the composite fiber has a sheath-core shape.   24. The nonwoven laminate according to claim 23, wherein the spunbond layer comprises monofilament fibers.   The nonwoven laminate according to claim 24, wherein the spunbond layer comprises a polyolefin other than polyethylene.   A nonwoven laminate structure comprising at least two nonwoven layers, wherein the nonwoven laminate structure has an overall bending modulus of 0.005 Nmm or less according to ASTM D 5732-95, and the nonwoven laminate greater than 2 N / 5 cm. Nonwoven, characterized in having a peel strength between the woven layers, wherein at least one of said nonwoven layers contains fibers comprising at least one polymer having units derived from at least about 50 weight percent propylene Laminated structure. Additionally, normalized to a basis weight of 25 gsm, and having a large hydrohead behavior than about 200 mm H ₂ O, nonwoven laminate structure of claim 26.   27. The nonwoven laminate structure of claim 26, wherein the at least two nonwoven layers comprise at least one meltblown layer and at least one spunbond layer.   29. The nonwoven laminate structure of claim 28, further comprising at least one additional meltblown layer or spunbond layer. At least one nonwoven layer has the following characteristics:
a. Crystallinity less than 50 percent b. Flexural modulus less than 50 kpsi c. A meltblown nonwoven layer comprising meltblown fibers comprising a propylene-based polymer characterized by having one or more characteristics of a melting point of less than about 140 ° C and / or a heat of fusion of less than 80 J / g The nonwoven laminated structure according to claim 26.   32. The nonwoven laminate structure of claim 30, wherein the meltblown fiber is further characterized by comprising a copolymer of propylene and an alpha-olefin, wherein the alpha olefin is preferably ethylene.   32. The meltblown nonwoven layer according to claim 31, wherein the alpha olefin is ethylene. 31. The propylene-based polymer is further characterized by having ¹³ C NMR peaks corresponding to regio errors at about 14.6 ppm and about 15.7 ppm, and wherein the peaks are of approximately equal intensity. The non-woven laminated structure described in 1.   32. The nonwoven laminate structure of claim 30, wherein the propylene-based polymer comprises from 3 weight percent to 20 weight percent ethylene.   32. The nonwoven laminate structure of claim 30, wherein the propylene based polymer comprises from 9 weight percent to 20 weight percent ethylene.   32. The nonwoven laminate structure of claim 30, wherein the propylene-based polymer has an MFR from 25 to 5000.   31. The nonwoven laminate structure of claim 30, wherein the propylene-based polymer undergoes chemically induced chain scission and has an MFR of 50 to 5000.   38. The nonwoven laminate structure of claim 37, wherein the chain scission is caused by combining the composition with a free radical initiator prior to extrusion.   39. The nonwoven laminate structure of claim 38, wherein the free radical initiator is of the peroxide type.   39. The nonwoven laminate structure of claim 38, wherein the free radical initiator is non-peroxide type.   38. The nonwoven laminate structure of claim 37, wherein the chain scission is caused by combining the composition with at least one peroxide-type and one non-peroxide-type free radical initiator.   32. The nonwoven laminate structure of claim 30, wherein the meltblown fiber has an average fiber diameter of less than about 12 microns.   29. The nonwoven laminate structure of claim 28, wherein the spunbond layer comprises fibers comprising a polyethylene-based material that includes at least a portion of the surface of the fibers.   27. The spunbond layer of claim 26, comprising composite structured fibers.   45. The spunbond layer of claim 44, wherein the composite fiber has a sheath-core shape. A nonwoven laminate comprising at least one meltblown nonwoven layer and at least one spunbond layer,
The at least one meltblown layer comprises fibers comprising a polymer having units derived from at least about 50 weight percent propylene, and the at least one spunbond nonwoven layer comprises a polyethylene-based material as the fibers. Comprising fibers characterized in that they constitute at least part of the surface of
Non-woven laminate.   48. The fiber of claim 46, wherein the at least one meltblown layer comprises fibers comprising a polymer having units derived from at least about 50 weight percent propylene and at least about 5 weight percent units derived from monomers other than propylene. Non-woven laminate product.

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