WO1982000953A1

WO1982000953A1 - Film formed from a thermoplastic polymeric resinous blend

Info

Publication number: WO1982000953A1
Application number: PCT/US1981/001234
Authority: WO
Inventors: Chem Co Dow; M Tusim
Original assignee: Dow Chemical Co
Priority date: 1980-09-16
Filing date: 1981-09-15
Publication date: 1982-04-01
Also published as: ES505534A0; IE52000B1; IT1142863B; EP0059739A4; DK170258B1; ZA816431B; EP0059739A1; CA1186096A; JPS57501631A; IT8149301A0; IE812141L; EP0059739B1; ES514470A0; KR830007752A; ES8400327A1; JPS6025052B2; US4376799A; ES8305801A1; KR860001861B1; BE890380A

Abstract

A thermoplastic film and container made from a chlorinated polyethylene blend. The composite film may be formed of a multilayer structure, in which a skin layer is formed of the chlorinated polyethylene resin blend. The composite multilayered structure is such that quietness is imparted without detracting from the extrudability and other physical characteristics necessary or practical applications. A vapor barrier may be included as a core layer. A particular application for the present invention is an ostomy bag.

Description

FILM. FORMED FROM A THE-RMOPLASTIC POLYMERIC RESINOUS BLEND

The invention primarily relates to a thermo¬ plastic film formed from a chlorinated polyolefin blend; to multilayered composite films in which at least one layer comprises the chlorinated polyolefin blend and another layer is a moisture and odor imper¬ meable barrier resin layer, and to medical pouches such as ostomy bags, packaging containers, protective clothing, and the like.

A preferred application of the multi- layered composite film is as an ostomy bag where there has existed a great need for a "quiet" or "rustle-free" bag which could be worn by its user in greater comfort and with a substantially lesser degree of awareness of the bags presence next to the wearer's skin due to its noiseless characteristics. Surgical drainage pouches, sometimes known as ostomy bags, permit drainage from parts of the body and are temporarily worn by a patient such as that illustrated in U.S. Patent No. 3,302,647, for example. Thus, an ostomy bag should have minimal or no "rustle", i.e., noise, when worn because the resulting noise can often be embarrassing or disturb¬ ing to the wearer. Also, without such noise, it is easier for the wearer to remove from his mind the fact that he is wearing an ostomy bag. Additionally, prior containers including ostomy bags, have been unable to provide adequate odor and moisture barrier properties while at the same time achieving a desir- able structural thinness and a high degree of quietness.

Present films for containers of this nature generally are made from polyethylene films or from more expensive plasticized polyvinyl chloride film, plasticized polyvinylidene chloride copolymer films and multilayered structures such as ethylene vinyl acetate/polyvinylidene chloride/ethylene vinyl acetate combination films. To a greater or lesser extent, the more desirable thin gauge containers having a high degree of odor and vapor barrier characteristics also have a high noise level such that they ".rustle" when worn by the user. Accord¬ ingly, there is a need for a substantially noise-free product which is economical to make, has good odor and moisture barrier properties, and has sufficient strength for its intended purposes.

The purpose of the present invention is to obtain a practical thermoplastic film particularly one useable in medical applications, which has physi- cal properties which provide a high degree of quiet¬ ness. Such a product should also have sufficient softness and comfort, heat sealability, strength or tougliness e.g., puncture resistance and, where desirable or necessary, adequate vapor, i.e., moisture, gas, and odor barrier properties. It has been discovered that a thermoplastic film container having all of the above desirable properties can be obtained by use of a multilayered film having at least one layer of a chlorinated polyethylene (CPE) blend with a layer of a barrier thermoplastic resin such as polyvinylidene chloride. Where the film is used as an ostomy bag, it must possess a degree of quietness which is near rustle- -free and insignificant to the background noise to accomplish its desired purpose. The barrier layer and the layer of CPE blends are combined in a multi- layer arrangement to form a composite film which is particularly well adapted for ostomy bags and other purposes where the strength, quietness and vapor barrier characteristics are desired. The degree of quietness is measured by a testing method developed for this invention.

More specifically, the present invention resides in a thermoplastic film having improved dart impact strength formed from a composition of a blend of polymeric resins wherein a primary component of said blend comprises from 40 to 95 weight percent of a chlorinated polyolefin having from 25 to 50 weight percent chemically combined chlorine, and wherein a secondary component of the blend comprises from 2 to 57 weight percent of an olefinic polymer or copolymer, and from 1 to 3 weight percent of a stabilizing composition to prevent degradation of the chlorinated polyethylene at extrusion tempera¬ tures for forming the film. The invention also resides in a thermo¬ plastic multilayer composite film comprising at least one layer of a blend of polymeric resins wherein a primary component of said blend cora- prises from 40 to 95 weight percent of a chlorinated polyolefin having from 25 to 50 weight percent chemically combined chlorine, and wherein a secondary component of the blend comprises from 2 to 57 weight percent of an ole- finic polymer or copolymer, and from 1 to 3 weight percent of a stabilizing composition to prevent degradation of the chlorinated polyethy¬ lene at extrusion temperatures for forming the film, and at least one other layer of a polymeric resinous material adhered to at least one surface of said one layer.

The invention further resides in a medical pouch comprising a multilayered composite film in which at least one first layer comprises a blend of polymeric resins wherein a primary component of the blend comprises from 40 to 95 weight percent of a chlorinated polyolefin having from 25 to 50 weight percent chemically combined chlorine, and wherein a secondary component of the blend comprises from 2 to 57 weight percent of an olefinic polymer or copolymer, and from 1 to 3 weight percent of a stabilizing composition to prevent degradation of the chlorinated polyethylene at extrusion tempera¬ tures for forming the film, .nd at least one second layer of a polymeric vapor barrier material adhered to at least one surface of the first layer or layers.

Figure 1 is an approximate graphical repre¬ sentation of the intensity and frequency levels of background noise against which the noise levels of prior art and other products, and the products of this invention were measured;

Figures 2 and 3 are approximate graphical representations of the intensity and frequency levels of prior art and other products, respectively; and

Figure 4 is an approximate graphical repre¬ sentation of the intensity and frequency level of a typical product made in accordance with the principles of this invention.

The invention is an improvement over current ostomy bag film, such as typified in U.S. Patent No. 3,524,795. In this particular prior art structure, polyethylene skins are formed about a Saran (poly- vinylidene chloride copolymer) resin core with glue layers between the skin and core to adhere the skins to the core. Such a film exhibits a noise level which, if it could be reduced by 15 or 20 percent, would make the film practically rustle-free and thus very attrac- tive to users. It has now been discovered that by introducing a blend of resins, a first or primary com¬ ponent of which is chlorinated polyethylene, and the second or secondary component of which is a low-density polyethylene, that the desired degree of quietness in the film could be achieved- It was additionally dis¬ covered that not only was quietness assured, but that the glue layers between the skins and the core while permissible for some applications, would not usually

Registered Trademark be required because of the natural adhesive character of the chlorinated polyethylene resin. One preferred embodiment of the invention employs the use of a chlorinated polyethylene resin such as that disclosed in an article entitled, "Structure-Property Relation¬ ships of Chlorinated Polyethylene", by N. K. Kalfoglou and H. L. Willi-ams in Polymer Engineering and Science, May, 1972, Volume 12, No. 3, starting at page 224 and in U.S. Patent Nos. 3,396,901, 3,454,544 and 3,678,873.

More specifically, the chlorinated olefin ^" polymers found to be useful for the pu.rposes of the present invention are preferably prepared by the chlorination, in suspension in an inert diluent, of polyethylene or interpolymers containing at least about 90 mole percent of ethylene in the polymer molecule with aijy remainder being one or more ethylenically unsaturated comonomers wherein such polymers are preferably of an essentially linear structure. Chlorinated olefin polymers contain from 25 to 50, and preferably from 30 to 42 weight percent of chemically combined chlorine and are characterized by having a relative crystallinity of between 15 and 28 percent when containing about 25 weight percent chlorine and a relative crystallinity of less than about 10 percent when containing about 34 or more weight percent chlorine, wherein said relative crystallinity is a measure of the ratio of the crystalline peak areas to the sum of the -amorphous plus crystalline peak area as determined by conventional X-ray diffraction techniques. Exemplary of preferred polyolefin materials to be chlorinated are those distinct species and varieties of essentially linear and unbranched highly porous, finely divided polymers containing at least about 90 mole percent ethylene in the polymer mole¬ cule with the remainder being one or more ethylenic- ally unsaturated comonomers such as the nonaromatic hydrocarbon olefins having 3 or more carbon atoms, including propylene, butene-1 and butene-2 and 1,7- -octadiene and the like; cycloaliphatic olefins such as 1,5-cyclopentene and cyclooctadiene and the like, substituted olefins such as acrylic acid and its esters; conjugated diolefins such as buta¬ diene and the like; and the alkenyl aromatic com- pounds such as styrene and its derivatives.

The olefinic polymer resins used as the secondary component of the blend in the present invention include low, linear low, or medium density polyethylene or ethylene copolymers which comprise ethylene with at least one monoethylenically unsatu¬ rated comonomer, especially another lower olefin or a carboxylic acid or an alkyl ester of a monoethy¬ lenically unsaturated carboxylic acid. Examples of such copolymers include ethylene-propylene, ethylene acrylic acid, ethylene methyl methacrylate, ethylene vinyl acetate, and the like. Blends of one or more of the ethylenic polymer resins may also be used as the secondary component. Methods of making ethylenic polymer resins described herein-above are readily known in the art.

The term "low-density polyethylene" as used herein means branched polyethylene having a density from 0.910 to 0.930 g/cc and a melt index from 0.1 to 10 dg/min. The term "linear low-density poly¬ ethylene" as used herein means low density polyethylene made by the low pressure polyethylene process. "Medium- -density polyethylene" may have a density from 0.931 to 0.940.

A chlorinated polyethylene (CPE) resin having a chlorine content range of from 25 to 50 weight percent results in an improved overall processability of the blend and in improved properties of the resulting film. The film quietness exhibited by the chlorinated poly¬ ethylene blend may be related to its rubbery or elastic nature. A preferred CPE resin has a chlorine content of about 36 weight percent, a melt index of about 2 and a density of about 1.16 with a crystallinity of less than about 2 percent.

A preferred resάn blend for the film of this invention c-an be, for example, one having from 70 to 80 percent by weight of the chlorinated polyethylene, such as identified above, from 17 to 27 percent by weight of a copolymer of ethylene vinyl acetate (EVA) and a stabilizer of up to about 3 percent by weight. Prefer¬ ably, the aforementioned blend composition includes from 1 to 2 percent by weight of a calcium stearate and about 1 percent by weight of epoxidized soybean oil as stabi¬ lizers in which the soybean oil is commercially available under the trade designation PARAPLEX G-60 or G-62. Normally, a stabilizer is a-αed to thermoplastic materials in very small amounts, typically from 500 tp 3000 parts per million (ppm) (0.3 percent) to prevent thermal degradation of such materials

® Registered Trademark

- at the elevated temperatures at which the materials are extruded. It has now been discovered that a sub¬ stantially greater amount of a stabilizer is needed for the extrusion of chlorinated polyethylene blends not only to prevent degradation of the blend but also to essentially prevent the generation of toxic HC1 vapors during extrusion of the blend. An amount of from 1 to 3 percent by weight of one or more stabi¬ lizers has proven to be effective in the extrusion of various CPE blends.

The barrier resin layer can be a vinylidene chloride-vinyl chloride copolymer, ethylene vinyl alcohol (hydrolyzed copolymer of vinyl acetate and ethylene), other barrier resins such as those identi- fied in U.S. Patent No. 3,549,389, for example. Such barrier resins are designed to produce a film which has excellent gas and water vapor barrier properties.

The overall thickness of a multilayer film is from 1.0 to 10.0 mils and preferably from 2.5 to 6.0 mils. In a particular three layered composite film structure for use as ostomy pouches, the outer or skin layers are each about 1.3 mils in thickness and the barrier resin core layer is about 0.25 mil providing for a composite thickness of about 2.85 mils. Of course, thicknesses of the individual film layers can vary widely depending on the degree of toughness and barrier properties desired for a particular application. Multilayer film structures used in this invention can be made by coextrusion methods and apparatuses such as typified by U.S. Patent Nos. 3,354,506, 3,557,265 and 3,625,348. The chlorinated polyethylene (CPE) blend formulation described above has been developed to balance fi.lm properties and extrudability of the resin blend. The more CPE resin in the blend, the quieter the film but the more difficult it is to extrude. The higher the chlorine content in the blend, the more likely the resin blend will therm¬ ally degrade at extrusion temperatures. Other properties also depend on the percentage of CPE in the blend. Thus the degree of softness and comfort is increased with an increase in the percentage of CPE in the blend because the CPE resin has a rela¬ tively low modulus when compared to other resins. Further, as the chlorine level of CPE is increased, the modulus can be lowered to increase quietness and comfort. The CPE blend films of this invention are also tough (as defined by dart impact strength) even though tensile strength properties are not as ^• high as in other films. The percentage of CPE in the blend c-an also affect sealability of the film as the CPE has a somewhat lower heat seal strength than that of polyethylene generally. However, the higher percentage of CPE in the blend can advantage¬ ously affect the radio frequency sealing because of its dielectric nature. The percentage of CPE in the resin blend does not significantly affect oxygen and vapor barrier properties since that is basically con¬ trolled by the barrier layer.

The dart impact strength of various mono- -layer and composite film laminates were tested, including 3 layered films including CPE blend skin layers of the invention. The dart impact strength tests were conducted according to ASTM D-1709 which determines the energy that causes a film to fail under specified conditions of impact of a free- -falling dart. The energy is expressed in terms of the weight (mass) of the dart falling from a specified height which would result in 50 percent failure of the specimens tested. Two methods are described: Method A employs a dart with a 38 mm diameter hemispherical head dropped from a height of 0.66 m. This method is used for films whose impact resistance requires masses of about 50 g. or less to about 2 kg to fracture them. Method B employs a dart with a 51 mm diameter hemispherical head dropped from a height of 1.52 m. Its range of applicability is from about 0.3 kg to 2 kg. The Standard Staircase testing method was used in which a uniform missile weight increment is employed during the test and the missile weight is decreased or increased by the uniform increment after test of each specimen, depending on the result (fail or no fail) observed for the specimen. The following results were observed as indicated in the following Table:

TABLE I

Drop Film Dart Height 'Thickness Weight ( ) (mil) (gram)

1. LDPE Film 0.66 2 80-120 0.66 3 120-190

2. LDPE/EVA - 2 layer film 0.66 2 150-170 0.66 3 190-270 0.66 4 280-290

LDPE/EVA/SARAN®/EVA/LDPE 5 layer film 0.66 1.5 ^• 120-130 0.66 3 130-165

CPE-EVA/SARAN®/CPE-EVA - 3 layer film 1.52 3 >700 CPE/EVA blend of 70 wt. 1.52 4 >800 percent CPE/30 wt. per¬ 1.52 5 >1000 cent EVA

Drop Film Dart Height CPE-LDPE Thickness; Weight Blend (mil) (gram)

CPE blends/

SARANVCPE 1.52 80 - 20 3 370 blends - 3 1.52 70 - 30 3 320 layer film 1.52 60 - 40 3 250 1.52 40 - 60 2.6 165 1.52 20 - 80 2.6 140 1.52 0 - 100 2.5 140

From the above Table, it should be noted that the impact strength of a monolayer film of LDPE in Exper¬ iment 1, having a thickness of 3 mil is relatively low at 120-190 grams. The impact strength of a composite film of LDPE/EVA in Experiment 2 of the same thickness of 3 mil is slightly improved at 190 to 270 grams due to the presence of the EVA layer. The 5-layered film

® m Experiment 3 illustrates that a layer of S.ARAN reduces the impact strength of a 3 mil thick film to 130-165 grams. Substitution of the CPE-EVA blend film in Experiment 4 for the LDPE film in Experiment 3 illustrates that the impact strength of a 3 mil thick¬ ness film in Experiment 4 according to the invention is substantially improved with a dart weight of greater than 700 grams. Experiment 5 illustrates that the dart weight increases with an increase in the -amount of CPE present in the blend from 140 grams (0 percent CPE) to 370 grams (80 percent CPE/20 percent LDPE).

In Experiment 2, the EVA layer had a thickness of .about 0.4 mil. In Experiment 3, each of the EVA layers had a thickness of about 0.2 mil; the SARA layer had a thickness of .about 0.25 mil, and the remain¬ ing thickness of the composite film being divided equally between the LDPE layers. In Experiment 4, the SARA layer had a thickness of -about 0.25 mil with the remaining thickness of the composite films being divided equally between the CPE blend layers.

In Experiments 4 and 5, the CPE component of the blend included -about 2-1/2 percent by weight of a stabilizer of which about 1-1/2 percent by weight was calcium stearate and about 1 percent by weight was epoxidized soybean oil-grade G-60.

Registered Trademark It generally is desirable to maintain as simple a structure as possible. A three-layer CPE blend skin/polyvinylidene chloride resin core/CPE blend skin combination is contemplated as a preferred embodiment of this invention. There is ordinarily enough natural adhesion between the skin and core layer such that an intermediate glue layer is not required. However, there may be particular instances for a film having more than three layers where inter- mediate glue layers become desirable. For example, a five-layer composite film comprising CPE blend skin/- glue layer/polyvinylidene chloride resin core/glue layer/CPE blend skin can be formed in which the two intermediate glue layers may be composed of a CPE blend which is extruded at a lower temperature than the outer skin layers of CPE blend to improve the output rate as well as the haze condition of the film. The CPE blend glue layer may also be of a different composition than the CPE blend skin layer. A hotter polymer on the skin layer provides a smoother surface to achieve improved haze condition and processability. A cooler intermedi¬ ate layer protects a heat sensitive core layer. The intermediate CPE blend layer between the skin and core layers can also be replaced by a glue layer. As is well known in the art, various glue compositions may be used as the glue layer depending on the characteristics desired for a composite film and the film materials used. Accordingly, synthetic resinous adhesive compositions may include low, linear low, or medium density poly- ethylene or ethylene copolymers which comprise ethylene with at least one monoethylenically unsaturated comonomer, especially another lower olefin or a car¬ boxylic acid or an alkyl ester of a monoethylenically unsaturated carboxylic acid. Examples of such copoly¬ mers include ethylene-propylene, ethylene acrylic acid, ethylene methyl methacrylate, ethylene vinyl acetate, and the like. Blends of one or more of the ethylenic polymer resins may also be used as the adhesive layer composition. The selection of the glue layer material is dependent on the composition of the skin and core layers.

In order to determine the quietness of the film of the present invention with that of prior art, other films such as films used in ostomy pouches and similar containers, for example, an apparatus was con¬ structed to flex plastic films in a controlled, repeat- able manner. This apparatus utilizes an 8.5 by 8.5 centimeter sample that is fastened to a holder in such a manner that the film sample forms a cylinder. The holder is fashioned such that one end of the cylindrical film sample is held in.a fixed position while the other end is rotated about the axis of the cylindrical film. Noise is generated when a wheel drive is put into contact with the rotating end of the sample holder and causes it to rotate 15.3° in one direction and 15.3° in the other direction. The frequency of this movement in opposite directions is taken at 1 cycle per second. A microphone is used to pick up the noise and the thus generated noise is analyzed to determine its frequency in a Harmonic Spectrum analyzer. The sound created by a sample in the above manner was measured by placing the microphone in the fixed end of the sample holder thereby generating an electrical signal that is pro¬ cessed or recorded as desired, as typified in Figures 2 to 4 of the drawing. To determine decibel readings the

- E microphone of the spectrum analyzer was replaced with a microphone of an audiometer to pick up the decibel readings. By this technique a direct reading of the sound level over the entire he-aring range is available as a single figure e.xpressed in dBA. The dBA unit was selected to report results as it is an accepted decibel noise unit used by most authorities.

Tests were run of film s.amples having various quantities of chlorinated polyethylene ("CPE") resin blended with either low density polyethylene ("LDPE") or linear low density polyethylene ("LLDPE"). The noise levels (or degree of quietness) were compared against background room noise and the noise generated by films currently commercially available, including films hav- ing a relatively high degree of quietness in motion. It - was initially thought that a comparison of decibel (dBA) readings would define the apparent and perceived improve¬ ment in quietness achieved by films of the present inven¬ tion over films of the prior art. Surprisingly, this did not occur in every instance. Because of this, the frequency value of the various film samples was also checked. This did consistantly confirm the apparent and perceived quietness improvement achieved by films of the present invention. Table II summarizes the general results of the findings of the tests.

TABLE II

Total Film Frequency**

Sample Material* Thickness** dBA Reading in Identification Composition in Mils Reading Hertz Units

Background — — 56 600 Noise

Prior Art EVA/PVDC/EVA 3.0 77 5,800 Sample I

Prior Art Monolayer PVC 8.6 59 750 Sample II

Prior Art PE/EVA/PVDC/EVA/PE 2.8 86 11,800 Sample III

Sample A-l 0% CPE, 100% LDPE 2.6 87 10,000

Sample A-2 0% CPE, 100% LLDPE 2.8 83 6,500

Sample B-l 17.5% CPE, 80% LDPE 2.7 83 5,000

Sample B-2 17.5% CPE, 80% LLDPE 3.0 79 6,700

Sample C-l 37.5% CPE, 60% LDPE 2.8 78 5,800

Sample C-2 37.5% CPE, 60% LLDPE 3.0 75 7,000

Sample D-l 57.5% CPE, 40% LDPE 2.9 77 3,800

Sample D-2 57.5% CPE, 40% LLDPE 3.1 75 3,000

-^1 td\

TABLE I I (Con' d)

Total Film Frequency**

Sample E-l 67.5% CPE, 30% LDPE 3.0 72 2,000

Sample E-2 67.5% CPE, 30% LLDPE 2.8 74 2,600

Sample F-l 77.5% CPE, 20% LDPE 3.3 75 3,500

Sample F-2 77.5% CPE, 20% LLDPE 3.3 74 3,000

Sample G-l 70.0% CPE, 27-1/2% EVA 3.0 72.5 —

Sample G-2 70.0% CPE, 27-1/2% LDPE 2.7 57 910

Sample H 97.5% CPE, 0% LDPE or 2.7 57 800 LLDPE

* PVC = Polyvinyl chloride; CPE = chlorinated polyethylene; LDPE = Low density polyethylene; LLDPE = Linear low density polyethylene

EVA = Ethylene vinyl acetate copolymer resin such as Elvax brand resin produced by duPont Chemical Company; PVDC = polyvinylidene copolymer such as Saran resin produced by The Dow Chemical Company. Approximate compositions where known. Samples B-l through Sample H include about 2.5% stabilizers in addition to the CPE blend. Each of the films of Samples B-l through G-2 are multilayered films having a PVDC core layer, the materials of the skin layers being designated in the Table.

** Approximate rounded off readings.

-^*!

As can be determined from Table II, there are varying degrees of difference in the recorded decibel noise level of the films. The group of films of Prior Art Samples I and III and Samples A-l through G-2, are all in the 72 to 87 dBA range, which provides some indication of relative -quietness. Yet a percept¬ ible difference in quietness is realized by those handl¬ ing films of a similar dBA reading, such as Samples D-l through G-2 as compared with Prior Art Sample I and Samples C-l and C-2 of this group. This perceived difference registers in the frequency readings where Samples D-l through G-2 all show frequency readings of less than 4000 Hertz while the remainder show frequency readings considerably in excess of 4000 Hertz. These frequency readings are all relative to the background noise level of about 600 Hertz.

To more clearly understand the meaning and significance of the improvements of this invention, reference can be made to the Drawing. Figure 1 illus- trates graphically by the jagged line in the chart the intensity and frequency of the background noise found in the room where the testing occurred. The frequency level of the background noise in this instance was about 600 Hertz. When typical prior art film and other film samples were tested, Samples I and C-l, graphically illustrated in Figures 2 and 3, respectively, demon¬ strated a frequency reading of about 5800 Hertz, con¬ siderably above the room background noise level of 600 Hertz, and clearly audible to an observer in the room. In comparison, the film sample of this invention had a frequency reading of less than 4000 Hertz, and as low as about 2000 Hertz for Sample E-l, which is graphically illustrated in Figure 4. This graphic representation of Figure 4 is much closer to that of the background noise of Figure 1 than to that of Figures 2 and 3. Samples E-l and E-2 are preferred because of their low noise levels, but S.amples D-l, D-2, F-l, and F-2 are suitable quiet films made in accordance with the discovery of this invention. The films of the present invention are extremely quiet, can be readily extruded and either heat or dielectrically sealed, and have excellent water vapor and odor barrier properties.

The films of Prior Art S-ample II and Sample H exhibit quietness levels below that of the films of this invention, both in the dBA and frequency readings. How¬ ever, prior .Art Sample II is a polyvinyl chloride mono¬ layer film and is about three times as thick as the film of this invention. This film, while very soft and quiet, has extremely poor water vapor barrier properties, per mil thickness, when compared with other films such as polyethylene or polyvinylidene chloride films. It, therefore, is necessary to make -an extremely thick film to have anything approaching adequate vapor barrier properties using polyvinyl chloride resin.

Sample H, while quiet, comprises a heavy con¬ centration of the relatively expensive chlorinated poly¬ ethylene resin. This results in higher costs when compared with the other film samples using blends of polyethylene in combination with^'chlorinated polyethylene. Also, the heavier the concentration of chlorinated poly¬ ethylene, the more difficult it is to manufacture the film, as discussed hereinbefore. Various properties, including the ultimate tensile strength and heat seal properties of a 3- -layer composite film of the invention was compared against a prior art sample as illustrated in Table III. The ultimate tensile properties of the thermoplastic film were tested in accordance with ASTM D-882 Method A which is a static weighing-constant-Rate-of-Grip Separation Test. This method employs a constant rate of separation of the grips holding the ends of the test specimen. Samples 1, 2 and 3 employed a 3-layered structure in which the skin layers were each composed of a blend of 70 percent by weight CPE; 27 percent by weight EVA and 3 percent by weight of a stabilizer mixture as defined in Experiment 4 of Table I. Sample 4 was a prior art sample of a 5-layer structure of PE/EVA/PVDC/EVA/PE.

TABLE III

Noise

Level Ultimate Dart Heal Seal

Film Gauge (dBA) Tensile Drop 360°F;30psi; Sample (mils) [Hertz] (psi) (gram) 1 sec.dwell

1. 3.0 71.0 MD >700 MD [1800 (3535) 3.7 bg-910] TD TD (978) 2.4

2. 4.0 73.5 MD >800 MD (3276) 3.7

TD TD (1122) 2.8

3. 5.0 75.2 MD >1000 MD (2856) 3.9

TD TD (1046) 3.3

4. 2.8 86 MD 125 MD (2697) 6.3

TD TD (2163) 4.9

MD - Machine Direction TD - Transverse Direction bg - Background Noise

The noise level of the composite films in

Samples 1, 2 and 3 showed an improvement in all thick¬ nesses over the noise level of Sample 4 having a com¬ posite film thickness of 2.8 mils. The frequency reading for film Sample 1 was found to be well within the desired range at less than 1800 Hertz with a back¬ ground noise of 910 Hertz. The ultimate tensile strength in the machine direction compared favorably

H. with the prior art sample while the dart drop test showed a substantial improvement over the prior art sample. Similarly, the heat seal test compared favorably with that of Sample 4.

Various properties, including the ultimate tensile strength, heat seal properties and dart impact strength were tested on a 3-layer film comprising outer skin layers of a blend of chlorinated polyethylene and linear low density polyethylene and a core layer of SARAN . The polymeric blend varied in proportion from 0 percent CPE to a maximum of 80 percent CPE. The CPE component included 1.5 parts of calcium stearate and 1.0 part of P.ARAPLEX® G-60 as stabilizers per 100 parts of CPE. An antiblocking agent (SiO,) was added in an amount of 3.5 parts per 100 parts of CPE. The following results were observed as indicated in Table IV.

TABLE IV

Thickness in mils Ultimate Heat Seal

Film (dBA)¹ Tensile 350°F-30 PSI Dart Weight³ Description [Hertz]² SI 3 SEC.DWEL (lb/in) (Grams)

80% CPE 3.0 MD 1920 MD 4.6 7400 20% LLDPE (74.0) TD 850 TD 5.5 [3860]

70% CPE 3.0 MD 2260 MD 5.5 7400 30% LLDPE (73.5) TD 1220 TD 5.2 [2860]

60% CPE 2.8 MD 2300 MD 5.1 379 40% LLDPE (75.0) TD 1450 TD 5.4 [3260]

40% CPE 2.8 MD 2350 MD 2.0 307 60% LLDPE (75.0) TD 1800 TD 2.2 [5430]

20% CPE 2.6 MD 2486 MD 2.3 223 80% LLDPE (78.8) TD 2190 TD 1.9 [7660]

0% CPE 2.5 MD 2810 MD 2.0 170 100% LLDPE (83.0) TD 2520 TD 2.2 [6710]

¹Background noise (56.0) - dBA background noise [ 570] - Hertz ³Height of Drop 26 inches MD ^■ Machine Direction TD - Transverse Direction

TABLE V

Thickness in Mils Ultimate Heat Seal

Film (dBA)¹ Tensile 350°F-30 PSI Dart Weight³ Description [Hertz] PSI 3 Sec. well(lb/in) (Grams)

80% CPE 3.0 MD 2177 MD 4.45 373 20% LDPE (75.0) TD 1076 TD 4.25 [3660]

70% CPE 3.0 MD 2271 MD 4.5 322 30% LDPE (72.0) TD 1170 TD 4.5 [2290]

60% CPE 3.0 MD 2494 MD 3.7 253 40% LDPE (77.0) TD 1188 TD 3.1 [3740]

40% CPE 2.6 MD 2566 MD 1.9 165 60% LDPE (77.8) TD 1304 TD 1.5 [5860]

20% CPE 2.6 MD 2808 MD 1.5 144 80% LDPE (82.5) TD 1835 TD 1.05 [5170]

0% CPE 2.4 MD 3587 MD 2.2 136 (87.0) TD 1941 TD 1.1 [12400]

All are 3 layer structures CPE + LDPE/SARANΘ/CPE LDPE *Background noise (56.0) - dBA ²Background noise [570] - Hertz ---Height of drop 26 inches MD - Machine Direction TD - Transverse Direction ©Registered Trademark

Although the ultimate tensile strength of the film decreased with an increase in CPE in the blend, the tensile strength for a blend of 80 percent CPE-20 percent LLDPE was found to be fully deficient. Heat seal strength and dart impact strength both showed substantial increases in strength with an increase in CPE in the blend. An improvement was also observed in the quietness of the film materials as the level of CPE in the blend was increased.

.The film of the present invention is a superior product capable of providing adequate service when com¬ pared to existing products yet maintaining a high degree of quietness so that applications of the product in the form of containers, such as ostomy bags where rustle- -free characteristics are of major significance, can be achieved. While certain representative embodiments and details have been provided for purposes of illustrating the invention, it will be apparent to those skilled in the art that various changes and applications can be made therein without departing from the spirit and scope of the invention. For example, a film made from a chlor¬ inated polyethylene blend could be combined with a layer of an adhesive resin, such as copolymers of ethylene/- acrylic acid or ethylene/vinyl acetate, for laminating to substrates such as metal or foam. An adhesive resin such as ethylene/vinyl acetate could also be blended with the chlorinated polyethylene resin. The film thick¬ ness, coloration or degree of transparency and toughness, can likewise be varied according to the needs of a parti¬ cular application. The products to be made from the film may not only reside in film pouches for surgical or other medical use, but may find application in many other products where quietness is an important factor, such as in clothing, diapers or in wrappings and other packaging uses.

Claims

WHAT IS CLAIMED IS:

1. A the.rmoplastic film having improved dart impact strength formed from a composition of a blend of polymeric resins wherein a primary com¬ ponent of said blend comprises from 40 to 95 weight percent of a chlorinated poly olefin having from

25 to 50 weight percent chemically combined chlorine, and wherein a secondary component of the blend com¬ prises from 2 to 57 weight percent of an olefinic polymer or copolymer, and from 1 to 3 weight percent of a stabilizing composition to prevent degradation of the chlorinated polyethylene at extrusion temper¬ atures for forming the film.

2. The film according to Claim 1 wherein the primary component of the blend preferably com¬ prises from 55 to 80 weight percent chlorinated polyethylene having from 30 to 42 weight percent chemically combined chlorine and the minor compo¬ nent comprises from 17 to 42 weight percent of the olefinic polymer or copolymer. -2B-

3. The film of Claim 1 or 2, wherein the secondary component is selected from a low, linear low, or medium density PE, .and the secondary copolymer component comprises ethylene and at least one ethylenically unsaturated comonomer.

4. The film of Claim 1, 2 or 3 having a noise level of less than 4000 Hertz when measured against a background noise of about 600 Hertz.

5. The film of any one of the preced¬ ing claims wherein the film has a thickness of from 1.0 to 10.0 mils.

6. The film of Claim 5 wherein the fi.lm thickness preferably is from 2.5 to 6.0 mils.

7. The film of any one of the preceding claims, wherein the stabilizing composition comprises about 1 to 2 percent by weight calcium stearate and about 1 percent by weight of epoxidized soybean oil.

8. A thermoplastic multilayer composite film comprising at least one layer of the film of any one of the preceding claims and at least one other layer of a polymeric resinous material adhered to at least one surface of said one layer.

9. The composite film of Claim 8, wherein said other layer is a vapor barrier layer and the total thickness of the composite film is from 1.0 to 10.0 mils.

10. The composite film of Claim 9 wherein the vapor barrier layer is selected from a vinyli- dene chloride-vinyl chloride copolymer.

11. The composite film of Claim 9 or or 10 wherein said one layer is adhered to oppo¬ site sides of said vapor barrier layer.

12. The composite film of Claim 9, 10 or 11, including at least one synthetic resinous glue layer positioned between said one layer and said vapor barrier layer.

13. The composite film of Claim 12, including at least one synthetic resinous glue layer positioned on at least one surface of said one layer or on said vapor barrier layer.

14. The composite.film of any one of Claims 8 to 13, wherein the film is laminated or coextruded onto a substrate.

15. The composite film of any one of Claims 8 to 13 used as a medical pouch or a wrap¬ ping film.

16. A medical pouch comprising a multi¬ layered composite film in which at least one first layer comprises a blend of polymeric resins wherein a primary component of the blend comprises from 40 to 95 weight percent of a chlorinated polyolefin having from 25 to 50 weight percent chemically com¬ bined chlorine, and wherein a secondary component of the blend comprises from 2 to 57 weight percent _t of an olefinic polymer or copolymer, and from 1 to 3 weight percent of a stabilizing composition to prevent degradation of the chlorinated polyethylene at extrusion temperatures for forming the film -and at least one second layer of a polymeric vapor barrier material adhered to at least one surface of the first layer or layers.

17. The medical pouch of Claim 16, wherein said vapor barrier material is a vinyli- dene chloride/vinyl chloride copolymer, and wherein said first layer is adhered to opposite sides of said second layer.

18. The medical pouch of Claim 16 or 17, including at least one synthetic resinous glue layer positioned between said first and second layers.

19. The medical pouch of Claim 16 or 17, including at least one synthetic resinous glue layer adhered on at least one surface of the first layer or on said second layer.

20. The medical pouch of any one of Claims 16 to 19, wherein the multilayered film has a thickness of from 1.0 to 10.0 mils and a noise level of less than 4000 Hertz when measured against a background noise of about 600 Hertz.

21. The medical pouch of any one of Claims 16 to 20, wherein the secondary component of the blend is .an ethylenic polymer resin selected from low density, linear low density, or medium density polyethylene; ethylene copolymers comprising ethylene and at least one monoethyleni¬ cally unsaturated comonomer, or blends of one or more of the ethylenic polymer resins.

22. The medical pouch of any one of Claims 16 to 21, wherein the primary component of the blend preferably comprises from 55 to 80 weight percent chlorinated polyethylene having from 30 to 42 weight percent chemically combined chlorine and the minor component comprises from 17 to 42 weight percent of the olefinic polymer or copoly¬ mer.