WO2001000408A1 - Quiet films and sheets and method of using them - Google Patents

Abstract

Monolayer and multilayer, quiet, polymeric films and sheets are based upon an ethylene-styrene interpolymer and have a noise emission level ≤ 50 dB(A) at frequencies between 4 kHz and 16 kHz. Such films and sheets, prepared as described herein, have use in a variety of applications such as ostomy bags (colostomy, ileostomy), trans-dermal delivery systems (TDDS), incontinence bags, medical collection bags, parenteral solution bags, and packaging of odorous food or products, as well as for protective clothing applications or soil fumigation, textile laminations for soft, quiet, and supple garments, hospital gowns, gloves, mattress and bedding covers, allergy-resistant or non-hypoallergenic pillow cases.

Description

QUIET FILMS AND SHEETS AND METHOD OF USING THEM

This Application claims the benefit of U. S. Provisional Application No. 60/141 ,745, filed June 30, 1999.

This invention relates to quiet films and sheets and to the use of such quiet films and sheets.

Monolayer or multilayer film and sheets structures having a vast variety of properties are well-known in the art. However, one disadvantage associated with most of such films and sheets, is that the monolayer films and sheets have a noise emission of more than (>) 50 decibels on scale A (dB(A)) at frequencies between 4 kilohertz (kHz) and 16 kHz, and multilayer films and sheets have a noise emission > 55 dB(A) at frequencies between 1 kHz and 16 kHz when being handled or crumpled. For example, in applications such as ostomy bags, protective clothing, or mattress covers, such a noise emission level is extremely undesirable. Therefore, there remains a need for monolayer polymeric films or sheets that have noise emission levels equal or below (<) 50 dB(A) in the 4-16 kHz frequency range, and multilayer polymeric films and sheets that have a noise emission < 55 dB(A) in the 1 -16 kHz frequency range when being handled or crumpled.

The quiet polymer films and sheets of the present invention meet those needs.

One embodiment of the present invention provides monolayer, quiet, polymeric films and sheets that have a noise emission level < than 50 dB(A) at frequencies between 4 kHz and 16 kHz.

Another embodiment provides multilayer film and sheet structures having a noise emission level < 55 dB(A) at frequencies between 1 kHz and 16 kHz and containing at least (>) one layer of a quiet polymeric resin composition.

A related embodiment is a multilayer film or sheet structure comprising at least one layer that has an ethylene-styrene interpolymer content of at least 35 weight percent, based on layer weight, and at least one barrier layer that comprises a rigid barrier polymer selected from amorphous polyesters, PET-G, an amorphous copolyester of isophthalic acid + terephthalic acid + ethylene glycol and 1.3-bis(2-hydroxyethoxy)benzene, either alone or blended with PET-G, PET, PBT, thermoplastic polyesters, an amorphous thermoplastic polyester or blend having a glass transition temperature (Tg) greater than (>) 50°C, cyclo-olefinic copolymers such as a copolymer of ethylene and cyclopentadiene, EVOH, PC, PVA, SAN, ABS, polypropylene, high density polyethylene, polymethyl- methacrylate (PMMA),polyamides or polyamide copolymer, PA-6, PA-6,6, PA-11 , and PA- 12, amorphous polyamides, MXD6 polyamide, PVDC, polyvinylidene chloride-vinyl chloride (PVDCA C) copolymer, polyvinylidene chloride-methyl acrylate(PVDC/MA) copolymer, PEN, syndiotactic polystyrene, PHAE and/or polystyrene. This multilayer film or structure provides a lower noise level than a multilayer film or structure that is identical save for lacking the ethylene-styrene interpolymer.

Still another embodiment provides a method of reducing the emission of noise in monolayer or multilayer film and sheets structures, the method comprising the steps of: a) blending a first polymeric resin with a second polymeric resin; and b) forming a monolayer polymeric film or sheet having a noise emission level < 50 dB(A) at frequencies between 4 kHz and 16 kHz; or c) forming a layer from the blended polymeric resins blend in a multilayer polymeric film or sheet having a noise emission level < 55 dB(A) at frequencies ranges between 1 kHz and 16 kHz.

The quiet polymeric films and sheets of the present invention are particularly useful for ostomy bags (colostomy, ileostomy), trans-dermal delivery systems (TDDS), incontinence bags, medical collection bags, cosmetic patches, parenteral solution bags, and packaging, as well as for protective clothing applications, textile laminations for soft, quiet, and supple garments, hospital gowns, gloves, mattress and bedding covers, allergy-resistant or non-hypoallergenic pillow cases.

As stated above, the present invention provides quiet, monolayer or multilayer, polymer films and sheets. Applicants have found that polymeric films or sheets consisting essentially of an ethylene-styrene interpolymer (ESI) provide quiet films and sheets, if used as a monolayer film or sheet, or provide quietness to any multilayer structure made from any other polymer or polymer compositions and having > one layer consisting essentially of an ESI.

The ESI is a substantially random interpolymer or SRIP comprising, in polymerized form, i) > one olefin monomers and ii) > one vinyl or vinylidene aromatic monomers and/or > one sterically hindered aliphatic or cycloaliphatic vinyl or vinylidene monomers, and optionally iii) other polymerizable ethylenically unsaturated monomer(s). "Interpolymer", as used herein, indicates a polymer wherein > two different monomers are polymerized to make the interpolymer.

"Substantially random", when used to refer to ESI, generally means that monomer distribution of said interpolymer can be described by the Bernoulli statistical model or by a first or second order Markovian statistical model, as described by J.C. Randall in POLYMER SEQUENCE DETERMINATION, Carbon-13 NMR Method, Academic Press New York, 1977, pp. 71-78.

Preferably, the SRIP contains no more than (<) 15 percent (%) of the total amount of vinyl or vinylidene aromatic monomer in blocks of vinyl or vinylidene aromatic monomer of more than 3 units. More preferably, the interpolymer is not characterized by a high degree of either isotacticity or syndiotacticity. This means that in the carbon-13 (C^) NMR spectrum of the SRIP, the peak areas corresponding to main chain methylene and methine carbons representing either meso diad sequences or racemic diad sequences should not exceed 75% of the total peak area of the main chain methylene and methine carbons.

Olefin monomers suitable for use in preparing SRIPs include, for example, olefin monomers containing from 2 to 20 (C2-20)' preferably from 2 to 12, more preferably from 2 to 8 carbon atoms. Particularly suitable olefin monomers include ethylene, propylene, butene-1 , 4-methyl-1-pentene, hexene-1 or octene-1 or ethylene in combination with one or more of propylene, butene-1 , 4-methyl-1-pentene, hexene-1 or octene-1. Most preferred are ethylene or a combination of ethylene with one or more C₃₈ alpha-olefins (α-olefins). The α- olefins do not contain an aromatic moiety.

Other optional polymerizable ethylenically unsaturated monomer(s) include strained ring olefins such as norbornene and C_{l 10} alkyl or C_6.10 aryl substituted norbomenes, with an exemplary interpolymer being ethylene/styrene/norbornene.

Vinyl or vinylidene aromatic monomers suitable for use in preparing SRIPs include, for example, those represented by Formula I:

Ar I

(CH 2)„

R¹ — C — C ( P2)₂

(Formula I) wherein R¹ is selected from radicals consisting of hydrogen and C1.4 alkyl radicals, preferably hydrogen or methyl; each R² is independently selected from radicals consisting of hydrogen and C1.4 alkyl radicals, preferably hydrogen or methyl; Ar is a phenyl group or a phenyl group substituted with from 1 to 5 substituents selected from halo, C^-alkyl, and C, ₄- haloalkyl; and n has a value from zero to 4, preferably from zero to 2, most preferably zero.

Particularly suitable vinyl or vinylidene aromatic monomers include styrene and lower alkyl- or halogen-substituted derivatives thereof. Preferred monomers include styrene, α-methyl styrene, the lower alkyl (C,-₄) or phenyl-ring substituted derivatives of styrene, such as for example, ortho-, meta-, and para-methylstyrene, t-butyl styrene, the ring halogenated styrenes, such as chlorostyrene, para-vinyl toluene or mixtures thereof. A more preferred aromatic monovinyl monomer is styrene.

"Sterically hindered aliphatic or cycloaliphatic vinyl or vinylidene monomers", generally means addition polymerizable vinyl or vinylidene monomers corresponding to the Formula:

A¹ I R¹ - C = C(R²)₂ wherein A¹ is a sterically bulky, aliphatic or cycloaliphatic substituent of up to 20 carbons, R¹ is selected from radicals consisting of hydrogen and C1.4 alkyl radicals, preferably hydrogen or methyl; each R² is independently selected from radicals consisting of hydrogen and C1 -4 alkyl radicals, preferably hydrogen or methyl; or alternatively R' and A¹ together form a ring system. "Sterically bulky" means that the monomer bearing this substituent is normally incapable of addition polymerization by standard Ziegler-Natta polymerization catalysts at a rate comparable with ethylene polymerizations. C2-20 olefin monomers that have a linear aliphatic structure such as propylene, butene-1 , hexene-1 and octene-1 are not considered as sterically hindered aliphatic monomers. Preferred sterically hindered aliphatic or cycloaliphatic vinyl or vinylidene compounds include monomers in which one of the carbon atoms bearing ethylenic unsaturation is tertiary or quaternary substituted. Examples of such substituents include cyclic aliphatic groups such as cyclohexyl, cyclohexenyl, cyclooctenyl, or ring alkyl or aryl substituted derivatives thereof, tert-butyl or norbomyl. Most preferred sterically hindered aliphatic or cycloaliphatic vinyl or vinylidene compounds are the various isomeric vinyl-ring substituted derivatives of cyclohexene and substituted cyclohexenes, and

5-ethylidene-2-norbornene. Especially suitable are 1-, 3-, and 4-vinylcyclohexene. If the SRIP contains a vinyl or vinylidene aromatic monomer and a sterically hindered aliphatic or cycloaliphatic monomer in polymerized form, the weight ratios between these two monomer types is generally not critical. Preferably, the SRIP contains either a) > one vinyl or vinylidene aromatic monomer or b) > one sterically hindered aliphatic or cycloaliphatic monomer.

The most preferred SRIPs are interpolymers of ethylene and styrene and interpolymers of ethylene, styrene and > one C3.8 α-olefin.

SRIPs usually contain from 0.5 to about 50, preferably from 1 to 50, more preferably from 2 to 48 mole percent (mol%) of > one vinyl or vinylidene aromatic monomer and/or sterically hindered aliphatic or cycloaliphatic vinyl or vinylidene monomer (collectively "non-olefin monomer") and from about 50 to 99.5, preferably from 50 to 99, more preferably from 52 to 98 mol% of > one C2-20 aliphatic olefin. The corresponding weight ranges for such mol% figures are from 1.8 to 78.8, preferably from 3.6 to 78.8, more preferably from 7.0 to 77.4 wt% non-olefin monomer and from 98.2 to 21.2, preferably from 96.4 to 21.2, more preferably from 93.0 to 22.6 wt% olefin monomer. F. Sernetz, R. Mulhaupt, and R.

Waymouth, in "Influence of polymerization conditions on the copolymerization of styrene with ethylene using Me2Si(Me4Cp)(N-fetτ-butyl) TiCI2/methylalumoxane Ziegler-Natta catalysts", Macromol. Chem. Phys., 197, 1071-1083 (1996) report a theoretical maximum of 66 mol% styrene in an ethylene/styrene copolymer. This equates to a styrene monomer content of 87.8 wt%, based on copolymer weight. See page 1072, Results and discussion, second paragraph.

For purposes of the present invention, the ESI has a styrene content that is desirably from 10 to about 70 wt%, based on interpolymer weight (2.9 to 38.6 mol%), preferably from 20 to 70 weight percent, based on interpolymer weight (6.3 to 38.6 mol%), and more preferably from 25 to 60 weight percent (8.2 to 28.8 mol%).

The melt index (I2) according to ASTM D 1238 Procedure A, condition E, of

SRIPs generally ranges from 0.01 to 50 grams per 10 minutes (g/10 min), preferably from 0.01 to 20 g/10 min, more preferably from 0.1 to 10 g/10 min, and most preferably from 0.5 to 5 g/10 min. The glass transition temperature (Tg) of SRIPs preferably ranges from -40 degrees centigrade (°C) to +35°C, more preferably from -20°C to +30°C, most preferably from -15°C to +15°C, measured according to differential mechanical scanning (DMS). The density (p) of a SRIP is generally > 0.930 grams per cubic centimeter (g/cm³⁾, preferably from 0.930 to 1 .045 g/cm³, more preferably from 0.930 to 1.040 g/cm³, most preferably from

0.930 to 1.030 g/cm³. The molecular weight distribution (MWD or M M_n) is generally from

1 .5 to 20, preferably from 1.8 to 10, more preferably from 2 to 5.

While preparing a SRIP, an amount of atactic vinyl or vinylidene aromatic homopolymer may be formed due to homopolymerization of the vinyl or vinylidene aromatic monomer at elevated temperatures. The presence of vinyl or vinylidene aromatic homopolymer is generally not detrimental for the purposes of the present invention and can be tolerated. The vinyl or vinylidene aromatic homopolymer may be separated from the SRIP, if desired, by extraction techniques such as selective precipitation from solution with a non-solvent for either the SRIP or the vinyl or vinylidene aromatic homopolymer. For purposes of the present invention, it is preferred that < 30 weight percent (wt%), preferably less than (<) 20 wt%, based on the total weight of the interpolymers of atactic vinyl or vinylidene aromatic homopolymer is present.

A skilled artisan may select typical grafting, hydrogenation, functionalizing, or other reactions well known to those skilled in the art to modify the SRIPs. The polymers may be readily sulfonated or chlorinated to provide functionalized derivatives according to established techniques. The SRIPs may also be modified by various chain extending or cross-linking processes including, but not limited to peroxide-, silane-, sulfur-, radiation-, or azide-based cure systems. A full description of the various cross-linking technologies is described in U.S. Patent (USP) 5,869,591 and USP 5,977,271 , the entire contents of both of which are herein incorporated by reference. Dual cure systems, which use a combination of heat, moisture cure, and radiation steps, may be effectively employed. Dual cure systems are disclosed in USP 5,91 1 ,940 and incorporated herein by reference. For instance, it may be desirable to employ peroxide crosslinking agents in conjunction with silane crosslinking agents, peroxide crosslinking agents in conjunction with radiation, sulfur-containing crosslinking agents in conjunction with silane crosslinking agents, etc. The SRIPs may also be modified by various cross-linking processes including, but not limited to, incorporation of a diene component as a termonomer in its preparation and subsequent cross linking by the aforementioned methods and further methods including vulcanization via the vinyl group using sulfur for example as the cross linking agent.

One method of preparing SRIPs includes polymerizing a mixture of polymerizable monomers in the presence of one or more metaliocene or constrained geometry catalysts in combination with various co-catalysts, as described in EP-A-0,416,815 and USP 5,703,187, both of which are incorporated herein by reference in their entirety. Preferred operating conditions for such polymerization reactions are pressures from atmospheric up to 3000 atmospheres (304 megapascals (mPa) and temperatures from - 30°C to 200°C. Polymerizations and unreacted monomer removal at temperatures above the autopolymerization temperature of the respective monomers may result in formation of some amounts of homopolymer polymerization products resulting from free radical polymerization.

Examples of suitable catalysts and methods for preparing SRIPs are disclosed in allowed U.S. Application Serial No. 09/302,067 filed April 29, 1999, which is a continuation of Application Serial No. 967,365, filed 28 October 1992, now abandoned, which is a continuation-in-part of U.S. Application Serial No. 702,475, filed May 20, 1991 , now abandoned; and USPs: 5,055,438; 5,057,475; 5,096,867; 5,064,802; 5,132,380; 5,189,192; 5,321 ,106; 5,347,024; 5,350,723; 5,374,696; 5,399,635; 5,470,993; 5,703,187; and 5,721 ,185 all of which are incorporated herein by reference.

The substantially random olefin/vinyl(idene) aromatic interpolymers can also be prepared by the methods described in JP 07/278230 employing compounds shown by the general formula:

Cp l _{R l}

Cp² R²

where Cp¹ and Cp² are cyclopentadienyl groups, indenyl groups, fluorenyl groups, or substituents of these, independently of each other; R and R² are hydrogen atoms, halogen atoms, C-_| .12 hydrocarbon groups , alkoxyl groups, or aryloxyl groups, independently of each other; M is a group IV metal, preferably Zr or Hf, most preferably Zr; and R³ is an alkylene group or silanediyl group used to cross-link Cp¹ and Cp²).

The substantially random olefin/vinyl(idene) aromatic interpolymers can also be prepared by the methods described in USP 5,658,625; WO 94/00500; and Plastics

Technology, page 25 (September 1992), the teachings of which are incorporated herein to the extent allowed by law.

Also suitable are the SRIPs that comprise > one olefin/vinyl aromatic/vinyl aromatic/olefin tetrad disclosed in WO-98/09999 (together with its US parent application serial number 08/708,869, filed 4 September 1996), the teachings of which are incorporated herein to the extent allowed by law. These interpolymers can be prepared by conducting the polymerization at temperatures of from -30°C to 250°C in the presence of catalysts as those disclosed in WO-98/09999-A. Particularly preferred catalysts include, for example, racemic- (dimethyl-silanediyl)-bis-(2-methyl-4-phenylindenyl)zirconium dichloride, racemic-

(dimethylsilanediyl)-bis-(2-methyl-4-phenylindenyl)zirconium 1 ,4-diphenyl-1 ,3-butadiene, racemic-(dimethylsilanediyl)-bis-(2-methyl-4-phenyl-indenyl)zirconium di-C1-4 alkyl, racemic- (dimethylsilane-diyl)-bis-(2-methyl-4-phenylindenyl)zirconium di-C1-4 alkoxide, or any combination thereof. It is also possible to use the following titanium-based constrained geometry catalysts, [N-(1 ,1 -dimethylethyl)-1 ,1 -dimethyl-1 -[(1 ,2,3,4,5-h)-1 ,5,6,7-tetrahydro-s- indacen-1 -yl]-silanaminato(2-)-N]titanium dimethyl; (1 -indenyl)(tert-butylamido)dimethylsilane titanium dimethyl; ((3-tert-butyl)(1 ,2,3,4,5-h)-1-indenyl)(tert-butylamido) dimethylsilane titanium dimethyl; and ((3-iso-propyl)-(1 ,2,3,4,5-h)-1-indenyl)(tert-butyl amido)dimethylsilane titanium dimethyl, or any combination thereof.

Further SRIP preparation methods are described in the literature. Longo and

Grassi (Makromol. Chem., Volume 191 , pages 2387 to 2396 [1990]) and D'Anniello et al. (Journal of Applied Polymer Science, Volume 58, pages 1701 to 1706 [1995]) report the use of a catalytic system based on methylalumoxane (MAO) and cyclopentadienyltitanium trichloride (CpTiCl3) to prepare an ethylene-styrene copolymer. Xu and Lin (Polymer Preprints, Am.Chem.Soc, Div.Polym.Chem., volume 35, pages 686, 687 [1994]) report copolymerization using a MgCl2/TiCl4/NdCl3/AI(iBu)3 catalyst to give random copolymers of styrene and propylene. Lu et al. (Journal of Applied Polymer Science, volume 53, pages 1453 to 1460 [1994]) describe the copolymerization of ethylene and styrene using a TiCl4/NdCl3/ MgCl2 /AI(Et)3 catalyst. Sernetz and Mulhaupt, (Macromol. Chem. Phys., volume 197, pages 1071 to 1083 [1997]) describe the influence of polymerization conditions on the copolymerization of styrene with ethylene using Me2Si(Me4Cp)(N-tert- butyl)TiCl2/methylaluminoxane Ziegler-Natta catalysts. Arai, Toshiaki and Suzuki (Polymer

Preprints, Am. Chem. Soc, Div. Polym. have described copolymers of ethylene and styrene produced by bridged metallocene catalysts. Chem. Volume 38, pages 349, 350 [1997]) and in USP 5,652,315. The manufacture of olefin/vinyl aromatic monomer interpolymers such as propylene/styrene and butene/styrene is described in USP 5,244,996, USP 5,652,315, or DE 197 11 339 A1. All the above methods disclosed for SRIP preparation are incorporated herein by reference to the extent allowed by law. The monolayer, or the multilayer, quiet film or sheet structures that contain at least one layer comprising an ESI of the present invention preferably contain from 25 to 100 wt%, more preferably from 35 to 100 wt%, most preferably from 45 to 100 wt%, of SRIP, based on the total weight of the structure.

The monolayer, or multilayer, quiet film or sheet structures that contain > one layer comprising an ESI of the present invention may contain one or more other polymers in addition to > one or more of the above-described SRIPs. If present, their amount generally is up to 75 wt%, more preferably from 0 to 65 wt%, most preferably from 0 to 55 wt%, based upon the total weight of such structure.

In the monolayer, quiet films or sheets such additional, optional polymer(s) is/are blended with the described SRIP(s). In the multilayered film structure containing > one layer of an ESI, such additional, optional polymer(s) may be included in the same layer as the SRIP, in a layer other than the SRIP layer or both.

Preferred additional, optional polymers are monovinylidene aromatic polymers or styrenic block copolymers. The most preferred additional, optional polymers are homopolymers or interpolymers of C2-20 aliphatic olefins or C2-20 olefins and containing polar groups.

Suitable monovinylidene aromatic polymers include homopolymers or interpolymers of > one monovinylidene aromatic monomer, or interpolymers of > one monovinylidene aromatic monomers and > one monomers interpolymerizable therewith other than an aliphatic -olefin. Suitable monovinylidene aromatic monomers are represented by the following formula:

Ar I Rⁱ _ c = CH₂ wherein R and Ar have the meanings stated in Formula I above. Exemplary monovinylidene aromatic monomers are those listed under Formula I above, particularly styrene.

Examples of suitable interpolymerizable comonomers other than a monovinylidene aromatic monomer include, for example, C₄-C₆ conjugated dienes, especially butadiene or isoprene, N-phenyl maleimide, acrylamide, ethylenically-unsaturated nitrile monomers such as acrylonitrile and methacrylonitrile, ethylenically-unsaturated mono- and difunctional carboxylic acids and derivatives thereof such as esters and, in the case of difunctional acids, anhydrides, such as acrylic acid, C^-alkylacrylates or methacrylates, such as n-butyl acrylate and methyl methacrylate, maleic anhydride, etc. In some cases it is also desirable to copolymerize a cross-linking monomer such as a divinyl benzene into the monovinylidene aromatic polymer.

The interpolymers of monovinylidene aromatic monomers with other interpolymerizable comonomers preferably have polymerized therein > 50 wt%, preferably > 90 wt% of > one monovinylidene aromatic monomers.

Styrenic block polymers are also useful as an additional, optional polymer in the monolayer, quiet film or sheet, or the multilayer film or sheet structure containing > one layer comprising an ESI, of the present invention. "Block copolymer" means elastomers having > one block segment of a hard polymer unit and > one block segment of a rubber monomer unit. However, the term is not intended to include thermoelastic ethylene interpolymers that are, in general, random polymers. Preferred block copolymers contain hard segments of styrenic type polymers in combination with saturated or unsaturated rubber monomer segments. The structure of the block copolymers useful in the present invention is not critical and can be of the linear or radial type, either diblock or triblock, or any combination of thereof.

Suitable unsaturated block copolymers include those represented by the following formulas:

A-B-R(-B-A)_n or A_x-(BA-)_y-BA

wherein each A is a polymer block comprising a monovinylidene aromatic monomer, preferably styrene, and each B is a polymer block comprising a conjugated diene, preferably isoprene or butadiene, and optionally a monovinylidene aromatic monomer, preferably styrene; R is the remnant of a multifunctional coupling agent; n is an integer from 1 to 5; x is zero or 1 ; and y is a number from zero to 4.

Methods for preparing such block copolymers are known in the art. Suitable catalysts for the preparation of useful block copolymers with unsaturated rubber monomer units include lithium based catalysts and especially lithium-alkyls. USP 3,595,942 describes suitable methods for hydrogenating block copolymers with unsaturated rubber monomer units to from block copolymers with saturated rubber monomer units. The structure of the polymers is determined by their methods of polymerization. For example, linear polymers result from sequential introduction of the desired rubber monomer into the reaction vessel when using such initiators as lithium-alkyls or dilithiostilbene and the like, or by coupling a two segment block copolymer with a difunctional coupling agent. Branched structures, on the other hand, result from use of suitable coupling agents having a functionality with respect to the block copolymers with unsaturated rubber monomer units of three or more. Coupling may be effected with multifunctional coupling agents such as dihaloalkanes or alkenes and divinyl benzene as well as with certain polar compounds such as silicon halides, siloxanes or esters of monohydric alcohols with carboxylic acids. The presence of any coupling residues in the polymer may be ignored for an adequate description of the block copolymers forming a part of the composition of this invention.

Suitable block copolymers having unsaturated rubber monomer units include, but are not limited to, styrene-butadiene (SB), styrene-isoprene(SI), styrene-butadiene- styrene (SBS), styrene-isoprene-styrene (SIS), α-methylstyrene-butadiene-α-methylstyrene and α-methylstyrene-isoprene-α-methylstyrene.

The styrenic portion of the block copolymer is preferably a polymer or interpolymer of styrene and its analogs and homologs including α-methylstyrene and ring- substituted styrenes, particularly ring-methylated styrenes. The preferred styrenics are styrene and α-methylstyrene, and styrene is particularly preferred.

Block copolymers with unsaturated rubber monomer units may comprise homopolymers of butadiene or isoprene or they may comprise copolymers of one or both of these two dienes with a minor amount of styrenic monomer.

Preferred block copolymers with saturated rubber monomer units comprise > one segment of a styrenic unit and at least one segment of an ethylene-butene (EB) or ethylene-propylene (EP) copolymer. Preferred examples of such block copolymers with saturated rubber monomer units include styrene/ethylene-butene (SEB) copolymers, styrene/ethylene-propylene (SEP) copolymers, styrene/ethylene-butene/styrene (SEBS) copolymers, and styrene/ethylene-propylene/styrene (SEPS) copolymers.

Hydrogenation of block copolymers with unsaturated rubber monomer units preferably uses a catalyst comprising a reaction product of an aluminum alkyl compound with a nickel or cobalt carboxylate or alkoxide under conditions sufficient to substantially completely hydrogenate > 80% of the aliphatic double bonds while hydrogenating < 25% of the styrenic aromatic double bonds. Preferred block copolymers are those where > 99% of the aliphatic double bonds are hydrogenated while < 5% of the aromatic double bonds are hydrogenated.

The proportion of the styrenic blocks is generally between 8 and 65 wt% of the total weight of the block copolymer. Preferably, the block copolymers contain from 10 to 35 wt% of styrenic block segments and from 90 to 65 wt% of rubber monomer block segments, based on the total weight of the block copolymer.

The average molecular weights of the individual blocks may vary within certain limits. In most instances, the styrenic block segments will have number average molecular weights (M_n) within a range of 5,000 to 125,000, preferably from 7,000 to 60,000 while the rubber monomer block segments will have a M_n in the range of 10,000 to 300,000, preferably from 30,000 to 150,000. The total average molecular weight of the block copolymer typically ranges from 25,000 to 250,000, preferably from 35,000 to 200,000.

Further, the above block copolymers may be modified by graft incorporation of minor amounts of functional groups, such as, for example, maleic anhydride (MAH) by any method well known in the art.

Block copolymers useful in the present invention are commercially available and include, for example, those supplied by Shell Chemical Company under the designation of KRATON™, those supplied by FINA Chemicals under the designation of FINAPRENE™ and FINACLEAR™ and those supplied by Dexco Polymers under the designation of VECTOR™.

Preferred additional, optional polymers are homopolymers or interpolymers of C₂₂₀ (preferably C₂_₁₈ and more preferably C_2.12) aliphatic olefins or C₂₂₀ (preferably C_{2 18} and more preferably C_{2 12}) olefins that contain polar groups.

Suitable aliphatic α-olefin monomers that introduce polar groups into the polymer include, for example, ethylenically unsaturated nitriles such as acrylonitrile, methacrylonitrile, and ethacrylonitrile; ethylenically unsaturated anhydrides such as MAH; ethylenically unsaturated amides such as acrylamide, and methacryiamide; ethylenically unsaturated carboxylic acids (both mono- and difunctional) such as acrylic acid and methacrylic acid; esters (especially lower, e.g. C-\ .Q, alkyl esters) of ethylenically unsaturated carboxylic acids such as methyl methacrylate, ethyl acrylate, hydroxyethyl acrylate, n-butyl acrylate or methacrylate, and 2-ethyl-hexylacrylate; and ethylenically unsaturated dicarboxylic acid imides such as N-alkyl or N-aryl maleimides such as N-phenyl maleimide. Preferably the polar group-containing monomers include acrylic acid, vinyl acetate, alkyl acrylates such as methyl, ethyl or butyl acrylate, maleic anhydride and acrylonitrile. Halogen groups, which can be included in the polymers from aliphatic olefin monomers, include fluorine, chlorine and bromine. Such polymers preferably include chlorinated polyethylenes (CPEs) or polyvinyl chloride (PVC). Preferred olefinic polymers for use in the present invention are homopolymers or interpolymers of an aliphatic, including cycloaliphatic, C2-I 8 olefin. Suitable examples are homopolymers of ethylene or propylene, and interpolymers of > two olefin monomers. Other preferred olefinic polymers are interpolymers of ethylene and > one other C₃₈ olefin. Preferred comonomers include 1 -butene, 4-methyl-1 -pentene, 1- hexene, and 1 -octene. The olefinic polymer may also contain, in addition to the olefin, one or more non-aromatic monomers interpolymerizable therewith. Such additional interpolymerizable monomers include, for example, C₄-C₂₀ dienes, preferably, butadiene or 5- ethylidene-2-norbomene (ENB). Their degree of long or short chain branching and the distribution can further characterize the olefinic polymers thereof.

One class of olefinic polymers is generally produced by a high pressure polymerization process using a free radical initiator resulting in the traditional long chain branched low density polyethylene (LDPE). The LDPE employed in the present composition usually has a density of < 0.94 grams per cubic centimeter (g/cm³) (ASTM D 792) and a melt index (l₂)of from 0.01 to 100, preferably from 0.1 to 50 grams per 10 minutes (g/10 min) (as determined by ASTM Test Method D 1238, condition I).

Another class is the linear olefin polymers which have an absence of long chain branching (LCB), such as the traditional linear low density polyethylene polymers (heterogeneous LLDPE) or linear high density polyethylene polymers (HDPE) made using Ziegler polymerization processes (for example, USP 4,076,698), sometimes called heterogeneous polymers.

HDPE consists mainly of long linear polyethylene chains. The HDPE employed in the present composition usually has a density > 0.94 g/cm³ as determined by ASTM Test Method D 1505, and an l₂ (ASTM-1238, condition I) of from 0.01 to 100, and preferably from 0.1 to 50 g/10 min. The heterogeneous LLDPE employed in the present composition generally has a density of from 0.85 to 0.94 g/cm³ (ASTM D 792), and an l₂ (ASTM-1238, condition I) of from 0.01 to 100, and preferably from 0.1 to 50 g/10 min. Preferably the LLDPE is an interpolymer of ethylene and > one other C3.18 α-olefin, more preferably a C3.8 α-olefin. Preferred comonomers include 1 -butene, 4-methyl-1 -pentene, 1 -hexene, and 1 -octene.

A further class is that of the uniformly branched or homogeneous polymers (homogeneous LLDPE). The homogeneous polymers contain no LCB and have only branches derived from the monomers (if having > two carbon atoms). Homogeneous polymers include those made as described in USP 3,645,992, and those made using single site catalysts in a reactor having relatively high olefin concentrations (as described in USPs. 5,026,798 and 5,055,438, the teachings of which are incorporated herein by reference). The uniformly branched/homogeneous polymers include polymers in which the comonomer is randomly distributed within a given interpolymer molecule and wherein the interpolymer molecules have a similar ethylene/comonomer ratio within that interpolymer.

The homogeneous LLDPE employed in the present composition generally has a density of from 0.85 to 0.94 g/cm³ (ASTM D 792), and an l₂ (ASTM-1238, condition I) of from 0.01 to 100, and preferably from 0.1 to 50 g/10 min. Preferably the LLDPE is an interpolymer of ethylene and > one other C3-18 -olefin, more preferably a C3.8 -olefin. Preferred comonomers include 1 -butene, 4-methyl-1 -pentene, 1 -hexene, and 1-octene.

Further, there is a class of substantially linear olefin polymers (SLOPs) that may be used in making a film or structure of the present invention. These polymers have a processability similar to LDPE, but the strength and toughness of LLDPE. Similar to the traditional homogeneous polymers, the substantially linear ethylene/-olefin (EAO) interpolymers have only a single melting peak, as opposed to traditional Ziegler polymerized heterogeneous linear EAO interpolymers that have > two melting peaks (determined using differential scanning calorimetry (DSC)). SLOPs are disclosed in USPs 5,380,810; 5,272,236 and 5,278,272, the relevant teachings of which are incorporated herein by reference.

The SLOP density, measured in accordance with ASTM D-792, generally ranges from 0.85 g/cm³ to 0.97 g/cm³, preferably from 0.85 g/cm³ to 0.955 g/cm³, and especially from 0.85 g/cm³ to 0.92 g/cm³. The SLOP l₂, according to ASTM D-1238, Condition 190°C/2.16 kg, generally ranges from 0.01 g/10 min to 1000 g/10 min, preferably from 0.01 g/10 min to 100 g/10 min, and especially from 0.01 g/10 min to 10 g/10 min.

Also, included are ultra low molecular weight ethylene polymers and EAO interpolymers that have an I2 > 1 ,000, or a M_n < 1 1 ,000.

The more preferred homopolymers or interpolymers of C2-20 aliphatic olefins that optionally contain polar groups are homopolymers of ethylene; homopolymers of propylene, copolymers of ethylene and > one other C4.8 α-olefin; copolymers of propylene and > one other C4.8 α-olefin; copolymers of ethylene and > one of acrylic acid, vinyl acetate, methyl acrylate, ethyl acrylate, butyl acrylate, maleic anhydride or acrylonitrile; copolymers of propylene and > one of acrylic acid, vinyl acetate, maleic anhydride or acrylonitrile; and terpolymers of ethylene, propylene and a diene. Especially preferred are LDPE, HDPE, heterogeneous and homogeneous LLDPE, SLOP, polypropylene (PP), especially isotactic PP and rubber toughened PP, low crystallinity propylene homo- and copolymers, syndiotactic PP, or ethylene-propylene interpolymers (EP), or ethylene-vinyl acetate (EVA) copolymers, or ethylene-methyl acrylate copolymers, or ethylene-ethyl acrylate copolymers, or ethylene-butyl acrylate copolymers, or ethylene-acrylic acid (EAA) copolymers, or any combination thereof. Other optional polymers are polynorbornnene and ethylene-vinyl acetate-carbon monoxide (EVACO) copolymers.

The quiet films and sheets of the present invention may contain one or more of the following additives: processing aids, such as fluoropolymers, silicones or siloxanes; inorganic fillers such as barium sulfate, calcium carbonate, mica, silica, silica gel, nanofillers and talc; slip additives such as fatty acid amides; antiblock additives; odor absorbers; humidity absorbers; molecular sieves; pigments; antistatic additives; antifog agents; antioxidants; UV stabilizers; dielectric heating sensitizing; pigments; colors; activated carbon; fragrance; nucleating agents; clarifiers; biocides; and anti-microbial additives. The additives may optionally be encapsulated in microgranules. At least one outside layer of the film may be subjected to a surface treatment such as corona treatment, flame treatment or plasma treatment to increase its surface tension and improve its printability.

The quiet films used in accordance with the present invention may be used as single or monolayer films or as a component film of a multilayer film structure. Examples of the multilayer film structures comprise, but are not limited to, 2 to 7 layers and could, for example, take the form of A/B/D/C/D/E/F or A/B/C/B/A or A/B/C/D/E or B/C/A/C/D or A/B/C/D, or B/A/C/D, or A/C/B/, or A B, with the "A" layer being the quiet film layer of the present invention. The quiet layer "A" may be an outside or a buried layer of the multilayer film. Structures having more than one "A" layer, i.e., quiet layer, are also contemplated.

When the quiet polymeric films or sheets are used as monolayer or multilayer structure, the thickness of the structure depends upon the intended end-use of the film or sheet as well as the individual properties of the layers. However, the total thickness of the quiet films or sheet as monolayer or multilayer structure typically ranges from 10 micrometers (μm) to 800 μm, with from 20 μm to 700 μm being more typical, and from 25 μm to 600 μm being most typical. As used herein, "sheet" means a film thicker than 10 mils (254 μm) as defined in "Film Extrusion Manual"(Chapter 2, "Film Application", page 9, Tappi Press, Atlanta, Ga., 1992). The definition of films and sheets can also be found in the Society of the Plastics Industry, Inc., where a "film" is a sheeting having a nominal thickness < 254 μm (0.010 inch); and a "sheet" (thermoplastic) is a flat section of a thermoplastic resin with the length considerably greater than the width and > 254 μm (10 mils) in thickness

The monolayer and multilayer film and sheets of the present invention may be prepared by techniques well-known in the art such as blowing, casting or calendering, co- extrusion, extrusion coating, extrusion lamination, or adhesive lamination. The films or sheets may also be oriented in one or two directions.

Selection of other polymers, which together with ESI make up a multilayer film structure, depends on planned end-uses of the structure. Such polymers typically include LDPE, LLDPE, ultra low density polyethylene (ULDPE), homogeneous EAO copolymers, HDPE, PP homo- or copolymers, rubber modified PP, low modulus PP homo- or copolymers, low crystallinity PP homo- or copolymers, syndiotactic PP homo- or copolymers, ethylene-propylene-diene monomer elastomer (EPDM), EP rubbers (EPR), substantially linear EAO copolymers, styrene-butadiene copolymers (SB or SBS), SEBS, SI, SIS, ethylene-alkyl acrylate copolymers, such as, for example, ethylene-methyl acrylate (EMA), ethylene-butyl acrylate (EBA), ethylene-ethyl acrylate (EEA), EVA, EAA, ionomer resins, elastomeric co-polyesters, ethylene-methyl acrylic acid copolymers (EMAA), polynorbornene, thermoplastic polyurethane, polyether-amide block copolymers, EVACO, MAH-modified polyethylene, MAH-modified EVA, MAH-modified EMA, MAH-modified EBA, MAH-modified PP, glycidyl methacrylate (GMA) modified EMA, GMA-modified EBA, GMA- modified EVA, polyether-block amide copolymers, polyamides, elastomeric co-polyesters, PVC, CPE, barrier polymers defined below, and blends thereof.

The use of copolymers of olefins and polar comonomers also improves high frequency (HF) sealing properties of the film or sheet.

The polymeric layers immediately adjacent to the ESI-containing film layer(s) typically function as adhesive or tie layers, while the other layers typically function as a barrier layer, a seal layer, a structural layer, an intermediate layer or a skin layer. The overall thickness of such a multilayer film structure depends, of course, upon the thickness of the individual polymeric films making up the multilayer film structure. However, the individual component polymeric film thicknesses depend upon a variety of factors, including the ease and cost of manufacturing a film of a given thickness, the physical and chemical properties of the individual film, the environment to which the multilayer film structure will be exposed, as well as the required properties of the film and the melt viscosities of the resins at their processing temperatures.

In some applications, such as ostomy or incontinence bag applications, such bags desirably emit no noise. However, when crumpled, most polymeric films, especially multilayer polymer films that comprise individual polymeric film layers having different rigidities (i.e., modulus), emit noise.

When a reduction in noise is desired, the ESI of the present invention may be blended, typically in amounts of > 35 wt%, with other polymeric resins to form polymeric films of the present invention. Typically, these polymeric multilayer barrier films have a noise level < 55 dB(A) at frequencies between 1 kHz and 16 kHz. In addition, these polymeric resins having quietness properties may be included as a component in a multilayer film structure of the present invention. Typically, the ESI will be present at > 35 wt% in the total film composition. Alternatively, a quiet polymeric film or sheet may be formed entirely from ESI and included as a component film in a multilayer film structure of the present invention.

In addition, the use of ESI as a noise dampening polymer in a multilayer structure is of higher importance when the structure contains a layer essentially made of a polymer having a storage modulus (G') > 2.0 x 10⁴ Newtons per square centimeter (N/cm²). Polymers of such high modulus usually impart a high noise level to the multilayer structure. Polymers that have a G' > 2.0 x 10⁴ N/cm² include barrier polymers like amorphous polyesters and copolyesters alone or in blend, such as glycol-modified polyethylene terephthalate (PET-G), an amorphous copolyester of isophthalic acid + terephthalic acid + ethylene glycol and 1.3-bis(2-hydroxyethoxy)benzene (commercially available from Mitsui Petrochemical under the trade designation B-100), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and other thermoplastic polyesters and copolyesters, an amorphous thermoplastic polyester or blend having a glass transition temperature (Tg) greater than (>) 50°C, cyclo-olefinic copolymers such as a copolymer of ethylene and cyclopentadiene, ethylene-vinyl alcohol (EVOH), polycarbonates (PC), polyvinyl alcohol (PVA), styrene-acrylonitrile copolymer (SAN), acrylonitrile-butadiene- styrene terpolymer (ABS), polymethyl-methacrylate (PMMA), polyamides homopolymers and copolymers, such as PA-6, PA-6,6, PA-11 , and PA-12, amorphous polyamides, MXD6 polyamide, polyvinylidene chloride (PVDC), polyvinylidene chloride/vinyl chloride copolymers (PVDCA C), polyvinylidene chloride/methyl acrylate copolymers (PVDC/MA), polyethylene naphthalate (PEN), syndiotactic polystyrene, PP homo and copolymers, HDPE, polylactic acid, polyhydroxy amino ether (PHAE), polystyrene and blends thereof.

Typically, when ESI or an ESI-containing polymer composition is used as part of a multilayer polymeric film structure, it may be present as part of any layer of the structure, although it is preferred to have quiet layer(s)containing ESI as a skin layer or close the outside of the structure as this is more beneficial for the quietness of the structure.

At least one surface of the film or sheet can be embossed or texturized to improve resistance to blocking, machinability or handleability, or impart some performance benefit like softness, suppleness or appearance.

Experimental Section

Determine the noise of the films of Tables III, V, VIII and XI is as follows:

Cut a 10 x 10 cm size sample of the film or sheet, with the machine (MD) and transverse direction (TD) parallel to the sides of the sample. Fix the specimen with double side adhesive tapes on two circular (32 mm diameter) holders spaced 90 mm distant of from each other. For thick and rigid specimens, use clamps to fix the samples. The film or sheet has the shape of a vertical cylinder (32 mm diameter) with one slit along its axis. The film or sheet MD is parallel to the axis of the cylinder. Eliminate folds from the cylindrical film sample. The bottom circular holder is stationary while the upper holder is connected to an alternating drive mechanism.

Place a microphone 17 mm from the edge at half height of the film cylinder, at 90° from the slit. Connect the microphone to a CEL 393 noise analyzer having an octave frequency filter. Set the noise analyzer in "P" (peak) mode, range 2. Enclose the whole setup, with the exception of the motor of the drive unit and the noise meter, in a sound insulated box (15 mm plywood/3 mm lead/8 cm rockwool from outside to inside). Internal dimensions of the box are 33 cm x 33 cm x 40 cm (length x width x height). After starting the motor, the film makes an alternative flexing motion with an angle of 65° at a flexing frequency of 0.6 Hz. Record noise made by the flexing motion of the film in the octave frequency bands from 16 Hz to 16 kHz in dB(A). Typically, make 2 to 4 measurements and calculate an average for each frequency band. Conduct the test at ambient temperature (approximately 20°C).

Table I identifies resins used for the films of the Examples (Ex) and Comparative Examples (Comp Ex).

Table I

Table I (continued)

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1 - As determined by ASTM D-1238 at 190°C/2 16 kg

2 - As determined by ASTM D-1238 at 230°C/2 16kg

3 - As determined by ASTM D-1238 at 230°C/3 8kg

4 - As determined by ASTM D-1238 at 300°C/1 2kg Ex 1 to 4 - Monolayer ESI Films

Prepare three different thermoplastic monolayer films, of varying surface texture and thickness by a cast film extrusion process from two ESI compositions (base resins), identified as INDEX^* DE 200.00 (ESI-1 ) and INDEX^* DS 201.00 (ESI-2). These base resins are substantially random ESI copolymers containing approximately 30 wt% styrene and 70 wt% ethylene for ESI-1 and approximately 69 wt% styrene and 31 wt% ethylene for ESI-2. The molecular weight is such that both base resins possess an I2 of approximately 1 g/10 minutes, measured at 190°C with a 2.16 kg weight. ^*INDEX is a trademark of The Dow Chemical Company.

Incorporate low molecular weight additives of erucamide and stearamide, at levels of 2000 parts by weight per million parts by weight of resin composition (ppm) and 1000 ppm respectively, in the melt of this base resin composition, to impart adequate surface slip and antiblock characteristics to the solid films prepared therefrom. Evaluate films of this composition that differ in thickness and surface texture. Description of the films is as follows:

Film of Ex 1 , base resin is ESI-1 , 72 ^»m thick, smooth surface texture.

Film of Ex 2, base resin is ESI-1 , 90 ^«m thick, finely embossed surface texture.

Film of Ex 3, base resin is ESI-2, 125 «m thick, smooth surface structure.

Prepare a fourth and independent 75 ^»m thick monolayer ESI film (Film of Ex

4) by blown film extrusion process, and subsequently evaluate the film for noise characteristics. Prepare this film from 100 percent INDEX^* DM 200.99, another ESI that contains approximately 60 wt% styrene and 40 wt% ethylene and has an I2 of 0.5 g/10 min

(190°C/2.16 kg).

Comp Ex A to H - Monolayer Films

Prepare several comparative monolayer cast films from a variety of soft and elastic thermoplastic formulations. These film compositions include: EMA copolymer, EVA copolymer, low crystallinity homogeneous EAO copolymer, LDPE, and low crystallinity PP resins. Specific compositions of Comp Ex A to H are given in Table II below. Table

Evaluate all films for their noise-producing characteristics, under a given deformation condition, according to the noise measurement test method described herein. Table III reports the results as noise in dB(A) versus the octave frequency band. Table III also includes the ground noise, which is the noise measured when the noise test equipment is running empty without film.

Table III

The data in Table III show that ESI-based films (Ex 1 to 4) all exhibit considerably lower noise generation than the films of Comp Ex A to H over most of the frequency range. Note that the films of Ex 1 to 4 are very quiet at the frequency bands of 1 kHz and above which are the most annoying for the human ear. The monolayer films comprising ESI have noise emission levels < 50 dB(A) in all frequencies from 4 kHz to 16 kHz.

Ex 5 to 6 and Comp Ex I to M - Monolayer Sheets

Produce seven monolayer cast extruded sheets of ESI and comparative resins of target thicknesses approximately 250 and 500 -m. Ex 5 and 6 comprise INDEX^* DE 200.00 (ESI-1 ) base resin, while Comp Ex I to M comprise LDPE, EVA copolymer or low crystallinity homogeneous EAO copolymer. These sheets have a smooth surface. Table IV describes film compositions for the Ex and Comp Ex.

TABLE IV

Evaluate all films for their noise-producing characteristics, under a given deformation condition, according to the noise measurement test method described herein. Table V reports the results as noise in dB(A) versus the octave frequency band.

Table V Noise in dB(A) for different octave frequency bands

Comparing in Table V the noise generated by the sheets of the two different target thicknesses (250 ^»m for Ex 5 and Comp Ex I, J, K and 500 «m for Ex 6 and Comp Ex L and M) demonstrates again that the ESI-based films are among the quietest sheets for both target thicknesses. Again, note that the sheets of Ex 5 and 6 are very quiet at frequencies of from 1 kHz to 16 KHz, those most annoying to the human ear.

The monolayer sheets comprising ESI have noise emission levels < 50 dB(A) at all frequencies between 4 kHz and 16 kHz.

Comp Ex N to T - Multilayer Films

Coextrude five layer symmetrical cast films of layer configuration A B/C/B/A with EVA or LDPE skins and a rigid core layer of PET-G, ABS, amorphous polyamide or PC. These films have two tie layers, each representing 7.5 % of the total film thickness. Also prepare monolayer cast films of the same composition as the skin layers and of comparable thickness. The composition of these films is listed in Table VI. All resins are described in Table I, above.

Table VI

In this film, the barrier layer is split into 5 alternating layers "barrier/tie". The sum of these barrier layers is reported

There is a high difference in modulus (rigidity) between the skin and the core resins of these films as shown in Table VII.

Determine the G' of each resin used in the films of Table VI as follows:

Make dynamic mechanical measurements (i.e., G' and Tangent Delta values) using one of two Rheometrics RDS-II instruments (S/N 024-12 and 024-40) running under Rheos 4.4.4 software for machine control and data collection. Test all samples, using a dynamic temperature ramp profile, from -100°C to approximately 150°C at 2°C/min with a torsional frequency of 10 radians per second (rad/s) and strain of 0.02 %. Compression mold individual specimens prior to submitting them for testing. Specimen dimensions are approximately 12.7 X 3.2 X 57.2 mm (0.5 X 0.125 X 2.25 inches).

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Measure the noise of the films of TABLE VI and report the results in Table VIII.

Table VIII Noise in dB(A) for different octave frequency bands

The films of Comp Ex O, P, Q, R and T are significantly noisier than the films of Comp Ex N and S that do not include the thin core layer of rigid resin. The higher noise of the films containing the rigid core layer is due to a lower "sound reduction index" of the film resulting from the incorporation of a layer of higher stiffness in the structure. Reducing the stiffness of a structure is a known method to increase its sound reduction index. (See, for example, Woods Practical Guide to Noise Control", Fifth edition, March 1972, page 117. Published by Woods Acoustics, a division of Woods of Colchester Limited, UK). This demonstrates that the incorporation of a thin layer of rigid polymer in a coextruded structure significantly increases the noise emitted by this structure. It may therefore be advantageous to find a method to reduce the noise of these coextruded structures containing a rigid layer. Rigid layer means that the G' modulus of this layer is > 2 x 10⁴ N/cm².

Ex 7 to 8 and Comp Ex U to Y - Multilayer Films Containing at Least One ESI Layer

Prepare five and four layers multilayer films containing a core layer of PVDC or PET-G (amorphous polyester) and skin layers of LDPE or CPE/EVA blends and EVA or ESI by cast co-extrusion. Table IX shows the resin composition and the thicknesses of the multilayered structures.

Table IX

Again, these coextruded films are combination of layers of relatively low to low storage modulus (e.g. LDPE, CPE, EVA, ESI) and layers of high modulus (e.g. PVDC, PET-G), as shown in Table X. Table X Storage modulus G' at 20°C

# : modulus of LDPE-1 , LDPE-3 and LLDPE-1 were not determined, but must be close or lower to the one of LDPE 501.

Table XI shows the noise levels for a 78 TΓI thick film of ESI/tie/PVDC/tie/ESI (Ex 7) and a 74 ^«m thick ESI/tie/PET-G/tie/ESI (Ex 8), as compared to commercial multilayer barrier films used for ostomy applications (Comp Ex U to X) and to multilayer LDPE/tie/PET- G/tie/LDPE film (Comp Ex Y).

The noise measurements show that the films of Ex 6 and 7 with ESI skin layers are the quietest of all the films in many of the frequency bands.

The coextruded film of Ex 6 (PVDC core layer and ESI skin layers) is significantly quieter in many frequency bands than the films of Comp Ex U, V, W and X that have LDPE or CPE and EVA based skin layers. Similarly, the coextruded film of Ex 7 (PET- G core layer and ESI skin layers) is significantly quieter in all frequency bands than that of Comp Ex Y (LDPE skin layers). This shows that the use of ESI in the composition of a multilayer film containing a "rigid" layer allows the production of quiet films with a noise level < 55 dB(A) in the octave frequency bands from 1 kHz to 16 kHz.

Determine the heat seal strength of the films in Table XII as follows:

Heat seal two pieces of film together on a laboratory heat sealer in the following conditions:

20 N/cm² sealing pressure, 1.5 second (sec) sealing time. Heat the upper sealing jaw at 180°C (film/film) while the lower jaw is at 50°C. Interpose a 13 «m thick polyester film between the film and the sealing bars to prevent sticking. The seal is parallel to the film TD. Cut 25.4 mm wide heat-sealed specimens and put them in the clamps of a tensile tester having 50 mm distance between the two clamps. Pull the two sides of the seal apart at the speed of 508 mm/min in the film MD. The maximum force required to break the specimen is recorded as the seal strength.

Determine the static coefficient of friction of the films in Table XII according the test method ASTM D 1894. Determine the tensile properties of the films in Table XI according the test method ASTM D 882, using the testing speed of 508 mm/min, a specimen of 25.4 mm width and a 50.8 mm initial grip distance.

Table XII summarizes the key performance properties of the two of commercial ostomy films (Comp Ex W and X) in comparison to one ESI-skinned multilayer barrier films of the present invention (Ex 7).

TABLE XII Properties of Multilayer Films.

Table XII shows that film of Ex 7 has physical and seal properties similar to the Comp Ex X and W. It could, therefore, be used for the production of ostomy bags.

Claims

1. A monolayer, quiet, polymeric film or sheet having a noise emission level equal or less than 50 dB(A) at frequencies between 4 kHz and 16 kHz.

2. The film or sheet of Claim 1 comprising at least 35 weight percent of an ethylene-styrene interpolymer, based on film or sheet weight.

3. The film or sheet of Claim 2, wherein the ethylene-styrene interpolymer has a styrene content of 10 to about 70 weight percent, based on interpolymer weight (2.9 to 38.6 mol percent).

4. The film or sheet of Claim 2, wherein the ethylene-styrene interpolymer has a styrene content of 20 to 70 weight percent, based on interpolymer weight (6.3 to 38.6 mol percent).

5. The film or sheet of Claim 2, wherein the ethylene-styrene interpolymer has a styrene content of 25 to 60 weight percent (8.2 to 28.8 mol percent).

6. The film or sheet of Claim 2, wherein the ethylene-styrene interpolymer content is at least 45 weight percent of the film or sheet composition.

7. An article of manufacture comprising the film or sheet of Claim 1 , the article being selected from trans-dermal delivery systems (TDDS), cosmetic patches, incontinence bags, medical collection bags, ostomy bags(colostomy, ileostomy), parenteral solution bags, protective clothing applications, textile laminations, hospital gowns, gloves, mattress and bedding covers, allergy-resistant or non-hypoallergenic pillow cases application.

8. A multilayer film or sheet having a noise emission level less than or equal to 55 dB(A) at frequencies between 1 kHz and 16 kHz.

9. The multilayer film or sheet of Claim 8 comprising an ethylene-styrene interpolymer in at least one layer, the film or sheet having a total ethylene-styrene interpolymer content in the film is 35 weight percent or more

10. The multilayer film or sheet of Claim 9, wherein the total ethylene- styrene interpolymer content is at least 45 weight percent of the film composition.

11. The multilayer film or sheet of Claim 9, wherein the ethylene-styrene interpolymer has a styrene content of 10 to 70 weight percent, based on interpolymer weight.

12. The multilayer film or sheet of Claim 9, wherein the film or sheet contains at least one layer of a rigid barrier polymer.

13. The multilayer film or sheet of Claim 12, wherein the rigid barrier polymer is selected from amorphous polyesters, PET-G, an amorphous copolyester of isophthalic acid + terephthalic acid + ethylene glycol and 1.3-bis(2-hydroxyethoxy)benzene, either alone or blended with PET-G, PET, PBT, thermoplastic polyesters, an amorphous thermoplastic polyester or blend having a glass transition temperature (Tg) greater than (>) 50°C, cyclo-olefinic copolymers such as a copolymer of ethylene and cyclopentadiene, EVOH, PC, PVA, SAN, ABS, polypropylene, high density polyethylene, polymethyl- methacrylate (PMMA),polyamides or polyamide copolymer, PA-6, PA-6,6, PA-11 , and PA- 12, amorphous polyamides, MXD6 polyamide, PVDC, polyvinylidene chloride-vinyl chloride (PVDCΛ/C) copolymer, polyvinylidene chloride-methyl acrylate(PVDC/MA) copolymer, PEN, syndiotactic polystyrene, PHAE and/or polystyrene.

14. An article of manufacture comprising the multilayer film of Claim 8, the article of manufacture being selected from ostomy bags (colostomy, ileostomy), trans dermal delivery systems, incontinence bags , medical collection bags .cosmetic patches, or protective clothing applications.

15. A method of reducing the emission of noise in monolayer or multilayer film and sheet structures, comprising the steps of: a) blending a first polymeric resin with a second polymeric resin; and b) forming a monolayer polymeric film or sheet having a noise emission level equal or below 50 dB(A) at frequencies between 4 kHz and 16 kHz; or c) forming a layer from the blended polymeric resins blend in a multilayer polymeric film or sheet having a noise emission level equal or below 55 dB(A) at frequencies between 1 kHz and 16 kHz.

16. A multilayer film or sheet structure comprising at least one layer that has an ethylene-styrene interpolymer content of at least 35 weight percent, based on layer weight, and at least one barrier layer that comprises a rigid barrier polymer selected from amorphous polyesters, PET-G, an amorphous copolyester of isophthalic acid + terephthalic acid + ethylene glycol and 1.3-bis(2-hydroxyethoxy)benzene, either alone or blended with PET-G, PET, PBT, thermoplastic polyesters, an amorphous thermoplastic polyester or blend having a glass transition temperature (Tg) greater than (>) 50°C, cyclo-olefinic copolymers such as a copolymer of ethylene and cyclopentadiene, EVOH, PC, PVA, SAN, ABS, polypropylene, high density polyethylene, polymethyl-methacrylate (PMMA),polyamides or polyamide copolymer, PA-6, PA-6,6, PA-11 , and PA-12, amorphous polyamides, MXD6 polyamide, PVDC, polyvinylidene chloride-vinyl chloride (PVDC/VC) copolymer, polyvinylidene chloride-methyl acrylate(PVDC/MA) copolymer, PEN, syndiotactic polystyrene, PHAE and/or polystyrene.