JP2004514756A - Air and moisture vapor permeable biodegradable film and process for producing the same - Google Patents

Abstract

Biodegradable films that are permeable to moisture vapor and air, acting as a barrier to liquids, are produced by high speed methods. The film about 1000 to about 4500 g / ^{m 2} / day order high moisture vapor permeability according to ASTM E96E and (MVTRs), and about 30 to about 2000 cc / cm ² / min of air breathable 90psi air pressure Have.

Description

【００３９】
実施例１Ｂの生分解性フィルムは、着用中の皮膚ケアと快適さのために、空気フロー（通気（ｖｅｎｔｉｌａｔｉｏｎ））、高い湿気蒸気透過、および液体バリヤーの諸性質が必要とされている、おむつの裏当てシート、生理用ナプキン、およびヘルスケア衣料の用途に適している。
【００４０】
実施例２Ａ〜２Ｈ
これら実施例においては、実施例１Ａに使用されたとおりの芳香族−脂肪族タイプのコポリエステルが同様の仕方でフィルム状に押出される。実施例２Ａ〜２Ｈのこれらフィルムは室温でＣＤおよび／またはＭＤ延伸されて下記に示されているとおり空気および湿気蒸気通気性の生分解性フィルムになる。
【００４１】

【００４２】
その他の生分解性ポリマー、たとえば、ポリラクチド、ポリカプロラクトン、スターチ、ポリビニルアルコール、ポリエステル、およびコポリエステル、は上記の観点での空気および湿気通気性フィルムを提供するように無機充填剤粒子をもって加工されることができる。
【００４３】
上記記述に照らして、当業者に理解されるであろうように、本発明の原理を使用して材料および条件に依存してバリエーションが生じるであろうことは理解されるであろう。
【図面の簡単な説明】
【図１】
実施例１Ａのフィルム表面の１０００倍率の顕微鏡写真である。
【図２】
実施例１Ａのフィルムの断面の２０００倍率の顕微鏡写真である。
【図３】
実施例１Ｂのフィルム表面の、かみ合いによる非延伸領域の、１０００倍率の顕微鏡写真である。
【図４】
実施例１Ｂのフィルム表面の、かみ合い延伸による延伸領域の、１０００倍率の顕微鏡写真である。
【図５】
実施例１Ｂのフィルムの延伸表面領域を通る断面の２０００倍率の顕微鏡写真である。[0001]
(Related application)
This application was filed on January 10, 2000, which is a continuation-in-part of U.S. application Ser. No. 09 / 080,063, filed May 15, 1998 and now becoming U.S. Pat. No. 6,013,151. It is a continuation-in-part of US application Ser. No. 09 / 480,374 and US application Ser. No. 09 / 395,627, filed Sep. 14, 1999. All of the above applications are incorporated herein in their entirety.
[0002]
(Field of the Invention)
The present invention relates to an air and moisture vapor breathable biodegradable plastic film and a method for producing the same.
[0003]
(Background of the Invention)
The production of plastic films goes back many years. For example, U.S. Pat. No. 3,484,835 (1968), issued to Trounstine et al. More than 30 years ago, discloses an embossed plastic having desirable handling characteristics and processing into useful articles such as diapers. It relates to an embossed plastic film. Since this point, numerous patents have been issued in this area. U.S. Patent No. 4,376,147 (1983) discloses embossed films in cross direction (CD) and machine direction (MD). U.S. Pat. Nos. 5,202,173 (1993) and 5,296,184 (1994) are manufactured by incrementally stretching embossed films and forming perforations to achieve breathability. Taught ultra-soft thermoplastic films. The film may contain a filler. As disclosed in US Pat. Nos. 5,200,247 and 5,407,979, polymer films of polycaprolactone (PCL) and starch polymer or polyvinyl alcohol (PVOH) are also subjected to incremental stretching. Produce a breathable product. More recently, U.S. Patent No. 5,865,926 discloses a cloth-like microporous laminate of a nonwoven fibrous web and a thermoplastic film that has air and moisture vapor permeability as well as liquid barrier properties. Published about how to manufacture.
[0004]
Methods for producing microporous film products have also been known for some time. For example, Liu U.S. Pat. No. 3,832,267 discloses a melt embossing of a polyolefin film containing an amorphous polymer dispersed phase prior to stretching or orientation to improve gas and moisture vapor transmission of the film. Teach you to do. According to Liu Patent '267, a film of crystalline polypropylene having a dispersed amorphous polypropylene phase is biaxially stretched (stretched) to produce an oriented non-perforated film having greater permeability. ) Before being stamped first. The dispersed amorphous phase acts to impart microvoids and enhances the permeability of otherwise non-perforated films to improve moisture vapor transmission (MVT). .
[0005]
In 1976, Schwarz published a paper describing polymer blends and compositions for making microporous substrates (Eckhard CA Schwartz (Biax-Fiberfilm), "New Fibrilated Film Structures, Manufactures, Utah). ”,Pap. Synth. Conf. (TAPPI), 1976, pages 33-39). According to this article, a film of two or more immiscible polymers, one polymer forming a continuous phase and the second polymer forming a discontinuous phase, separates when stretched, whereby the polymer This leads to voids in the matrix and increases the porosity of the film. The continuous film matrix of the crystallizable polymer may be filled with an inorganic filler such as clay, titanium dioxide, calcium carbonate, etc. to provide microporosity in the stretched polymer substrate. .
[0006]
Numerous other patents and publications disclose the phenomena of making microporous thermoplastic film products. For example, EP 141592 discloses the use of a polyolefin containing a dispersed polystyrene phase, especially ethylene vinyl acetate (EVA), to produce a voided film that when stretched improves the moisture vapor permeability of the film. . This EP '592 also discloses that the EVA film can be embossed with thick and thin areas, and then stretched to provide a voided film first, which can be further stretched to produce a net-like product. , A sequential process is disclosed. U.S. Pat. Nos. 4,452,845 and 4,596,738 also disclose stretched thermoplastic films, wherein the dispersed phase is filled with calcium carbonate to impart microvoids upon stretching. Or polyethylene. U.S. Pat. Nos. 3,137,746, 4,777,073, 4,814,124, and 4,921,653 disclose that a polyolefin film containing a filler is first embossed and then the film. Discloses the same method as described by the above publication with the step of stretching to provide a microporous product. Other patent publications have also been issued, including WO 98/23673, which includes an improved moisture vapor transmission rate produced by mixing a copolyester resin with an inorganic filler. The present invention relates to a thermoplastic copolyester film having:
[0007]
Biodegradable and / or compostable products help preserve environmental resources and prevent the generation of additional waste. Both producers and consumers are aware that landfills and other landfills have a finite amount of space, and are more biodegradable and / or compostable than non-biodegradable and / or non-compostable products. It will approve and pursue the products that can be transformed. The requirement for biodegradability and / or compostability is particularly important in frequently used disposable products such as baby diapers, feminine hygiene products, hospital sterile drapes and the like. is there.
[0008]
Thermoplastic films that are biodegradable and / or compostable are known in the art. U.S. Patent No. 5,407,979 discloses a biodegradable thermoplastic film composed of three components, an alkanoyl polymer, a destructurized starch, and an ethylene copolymer. The components can be extruded and the film can be stretched to form a breathable film. U.S. Pat. No. 5,200,247 discloses a biodegradable thermoplastic film containing an alkanoyl polymer / polyvinyl alcohol (PVA) blend. U.S. Pat. No. 5,196,247 discloses a compostable polymer composite sheet and a method of making or complexing the same.
[0009]
A fully biodegradable and / or compostable soft cloth-like composite is disclosed in US Pat. No. 5,851,937. The composite is made by incrementally stretching one or more plies of a fully biodegradable and / or compostable nonwoven web and plastic film to provide a soft, cloth-like feel.
[0010]
There are still disadvantages in the production of breathable films and laminates that are liquid barriers. It is difficult to obtain a liquid barrier film of sufficient strength while maintaining the properties of biodegradability, air permeability and moisture vapor transmission.
[0011]
(Summary of the Invention)
The present invention relates to a biodegradable film that is permeable to both air and moisture vapor and is a barrier to liquids. These films are about 1000 g / m 2 at 100 ° F. and 95% relative humidity (RH) according to ASTM E96E.²Per day / moisture vapor transmission rates (MVTRs) and about 30 cc / cm at 90 psi air pressure.²/ Per minute.
[0012]
The above-referenced U.S. patent applications Ser. Nos. 09 / 080,063 and 09 / 480,374 disclose incrementally stretched films having high MVTRs. These applications are preferably from about 1200 to about 4500 g / m²Per day for incrementally stretched embossed and non-embossed films having MVTRs on the order of / day. Breathable laminates of these films with nonwoven substrates have also been disclosed.
[0013]
The present invention relates to further improvements in biodegradable films and laminates that are permeable to both air and moisture vapor. In a broad form of the invention, the biodegradable film comprises a blend of a biodegradable thermoplastic polymer with a mechanical pore forming agent, such as an inorganic filler of calcium carbonate, silica and zeolite. The pore-forming agent in the film or laminate is acted upon in a stretch, preferably an incremental stretch, to form a microporous, film, or fibrous web and film laminate. Biodegradable polymers such as starch polymers or polycaprolactone (PCL) blended with polyvinyl alcohol (PVA), which can be film-formed, are suitable. Other biodegradable polymers include polylactide (PLA), polyester and copolyester.
[0014]
The biodegradable films and laminates can be used for diaper backing sheets, sanitary napkins and pats, and other medical, packaging and clothing applications. Biodegradable films are particularly suitable for these and other similar applications because of their air permeability, moisture vapor permeability and water impermeability. The advantages and properties of the biodegradable films of the present invention and their method of manufacture will be better understood with reference to the following detailed description.
[0015]
(Detailed description of the invention)
The main object of the present invention is to provide at least about 30 cc / cm at 90 spi air pressure.²Per minute and about 1000 g / m at 100 ° F. and 95% relative humidity (RH) according to ASTM E96E.²It is to provide an air and moisture vapor permeable biodegradable film having a MVTR greater than / day. It is a further object of the present invention to produce these regularly breathable, stretch-stretched, biodegradable thermoplastic films of regular gauge, uniform porosity, and without breakage.
[0016]
A. Biodegradable film and laminate materials
Biodegradable film compositions can be achieved by blending the biodegradable thermoplastic polymer with appropriate additives and pore-forming fillers to provide an extrudate or film. The film may be laminated with a nonwoven web. Calcium carbonate, barium sulfate, silica, and zeolite particles are the most common fillers. As described above, providing a biodegradable film with different polymer phases in the film such that when the film is stretched at ambient or room temperature, microvoids are created that impart breathability and moisture vapor transmission It is known to do. These methods are described in U.S. Patent Nos. 5,200,247 and 5,407,979. In contrast, the present invention involves the use of inorganic fillers to impart high air permeability and high MVTRs with liquid barrier properties to the biodegradable film.
[0017]
These and other objects, as set forth above, provide that in a preferred form of the invention, (a) from about 40 to about 75% by weight of a biodegradable polymer of the type identified above; A composition with about 60% by weight of inorganic filler particles, such as calcium carbonate, zeolite, silica, talc, barium sulfate, mica, etc., is first melt blended, and then the melt blended composition is mixed with other additives. Extruding into the nip of a roller to form a film at a speed on the order of at least about 550 fpm to about 1200 fpm without draw resonance, and at that speed substantially and uniformly applying the film to the film Applying an increasing stretching force along the transverse line and through its depth to provide a biodegradable microporous film; Thus it is achieved.
[0018]
In particular, in a preferred embodiment, the melt-blended composition comprises essentially about 60 to about 75% polyester, such as the aliphatic-aromatic copolymers described in WO 98/23673, which is incorporated herein. Polyester. In particular, these thermoplastic copolyesters may be comprised of at least one aliphatic dicarboxylic acid, at least one aromatic dicarboxylic acid, and at least one aliphatic diol having from 4 to about 12 carbon atoms. Alternatively, the thermoplastic copolyester may be composed of at least one aromatic dicarboxylic acid, at least one aliphatic dicarboxylic acid and a polyalkylene ether. The aliphatic dicarboxylic acid is selected from the group consisting of adipic acid, glutamic acid, cyclohexanoic acid, and mixtures thereof; at least one of the aromatic dicarboxylic acids comprises terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and mixtures thereof. And at least one of the aliphatic diols is 1,4-butanediol, cyclohexane dimethanol, a polyalkylene ether compound, which is poly (ethylene glycol), poly (tetramethylene glycol) and poly (propylene glycol). )), And mixtures thereof. Thermoplastic copolyesters may be composed of various combinations of aromatic dicarboxylic acids, aliphatic diols, cycloaliphatic dicarboxylic acids, polyalkylene ethers, and the like, as examples of copolyesters within the scope of the present invention. Are all described in WO 98/23673.
[0019]
Other polymers are ester-ether polyesters (Hytrel and Armtel); nylon-ether polyesters (Pebax); polyethylene terephthalate (PET); polyvinyl alcohol (PVA); polycaprolactone (PCL); starch; , PCL or blends with PLA; polyesters such as polyhydroxy (butyrate) (PHB), polyhydroxy (valerate) (PHV); and mixtures thereof. Preferably, about 25-40% of calcium carbonate, silica, barium sulfate, or zeolite is used, which has an average particle size of about 1 to about 10μ.
[0020]
The film may be laminated with a biodegradable nonwoven, which preferably comprises a melt-stable lactide polymer of the type disclosed in US Pat. No. 5,539,081, ie, a polylactide nonwoven (PLA). Include. All nonwoven filaments are made exclusively of polymers or polymer mixtures derived from lactic acid, ie, L-lactic acid, D-lactic acid, or a mixture of L-lactic acid and D-lactic acid. Other nonwovens that are biodegradable and / or compostable include cotton nonwovens, cellulosic nonwovens, aliphatic-aromatic copolyesters, and blends thereof.
[0021]
In the above method, the melt-blended composition is extruded as a web from a slot die, through a cooling zone provided by an air knife, and then through a nip of a roller into a film at high speed. Embossed or flat (non-embossed) films can be produced. The use of an air knife, as explained above, helps to eliminate the draw resonance phenomenon, which is known, for example, by reference to US Pat. No. 4,626,574. Also, as described in co-pending U.S. application Ser. No. 09 / 395,627, filed Sep. 14, 1999, which is incorporated herein in its entirety, a flow of cooling gas is provided in a cooling zone. An apparatus is used for directing the flow to flow substantially parallel to the web surface. For example, devices such as those shown in U.S. Patent Nos. 4,718,178 and 4,779,355 may be used, and the entire disclosures of these patents are incorporated herein. After cooling, an incremental stretching force is applied to the film along a line that traverses the film substantially uniformly and through its depth to provide an incrementally stretched embossed film or flat with high MVTR and air permeability. Provide a film.
[0022]
Flat films are made in accordance with the present invention by extruding the web into the nip of a roller that provides a polished chrome surface to form a flat film. Flat film is about 1000 g / m²/ Day resulting in a microporous film product having a high MVTR. It has been found that flat films can be stretched more uniformly than embossed films. The stretching process may be performed at ambient, room, or elevated temperatures, as is understood in the art. Again, as understood in the art, "ambient" means the ambient temperature or atmosphere that is possible whatever the process conditions present around the film. As mentioned above, a laminate of the microporous film may be obtained with a nonwoven fibrous web.
[0023]
In a preferred embodiment, the microporous laminate uses a film having a gauge or thickness of 0.25 to 10 mils, and depending on the application, the film thickness will vary, and most preferably In disposable applications, the thickness is on the order of about 0.25 to 2 mils. The nonwoven fibrous web of the sheet to be laminated usually has a thickness of about 5 g / yd.²~ 75 g / yd²Weight, preferably from about 20 to about 40 g / yd²And The composite or laminate can be incrementally stretched in the cross direction (CD) to form a CD stretched composite. Further, after the CD stretching, stretching in the machine direction (MD) may be performed to form a composite stretched in both the CD and MD directions. As noted above, this microporous film or laminate requires baby diapers, baby training pants, menstrual pads and underwear, and moisture barrier and air permeable properties as well as fluid barrier properties. It may be used for many different applications, such as the like done.
[0024]
B. Stretching machine for microporous films and laminates
A number of different stretching machines can be used to stretch the film or laminate of the nonwoven fibrous web and the microporous forming film. These laminates of staple fiber nonwoven carded fibrous web or nonwoven spunbonded fibrous web may be drawn using the following drawing machines and techniques:
[0025]
1.Diagonal meshing stretching machine
A diagonal intermeshing stretcher consists of a pair of left and right spiral helical gear-like elements on a parallel shaft. The shaft is located between the two side plates of the machine, the lower shaft is located in a fixed bearing, and the upper shaft is located in a bearing in a vertically slidable member. The slidable member is vertically adjustable by a wedge-shaped element operable by adjusting a screw. Unscrewing or fitting the wedge moves the vertically slidable members down or up, respectively, further engaging or disengaging the gear-like teeth of the upper meshing roll with the lower meshing roll. A micrometer mounted on the side frame can be used to indicate the depth of engagement of the teeth of the engagement roll.
[0026]
Air cylinders are used to hold the slidable members firmly in their lower mating position against the adjustment wedge, against the upward force exerted by the material being stretched. These cylinders are retracted to disengage the upper and lower engagement rolls from each other, either for the purpose of passing material through the engagement device or in combination with a safety circuit that, when activated, opens all nip points of the machine. You can also.
[0027]
Driving means is typically used to drive the fixed intermeshing roll. If the upper meshing roll can be disengaged for the purpose of passing material through the machine or for safety, ensure that one meshing roll falls between the teeth of the other meshing roll when re-engaging, and An anti-backlash gearing arrangement between the upper and lower meshing rolls to ensure that the potentially damaging physical contact between the mating teeth addendum is avoided. It is preferred to use. If the interlock roll is to be maintained in an interlocked state, the upper interlock roll typically does not need to be driven. Driving may be accomplished by driven rolls through the material being stretched.
[0028]
The meshing roll is very similar to a fine pitch helical gear. In a preferred embodiment, the rolls have a diameter of 5.935 inches, a helical angle of 45 °, a normal pitch of 0.100 inches, a diameter pitch of 30 and a 14 1/2 diameter pitch. It has a pressure angle of ° and is basically a long tip gear. This results in a narrow, deep tooth profile that allows about 0.005 inch clearance on the tooth side for meshing and material thickness up to about 0.090 inch. The teeth are not designed to transmit rotational torque, and there is no metal-to-metal contact in normal mesh extension operations.
[0029]
2.Lateral meshing stretching machine
The CD mesh stretcher is the same as the diagonal mesh stretcher, with differences in the design of the mesh roll and other minor areas described below. It is important that the CD engagement element incorporates means to keep the shafts of the two engagement rolls parallel as the top shaft is raised and lowered, since the CD engagement element is capable of large engagement depths. This is necessary to ensure that one engaging roll always fits between the teeth of the other engaging roll and that the engaging teeth avoid physical contact that could damage them. This parallel movement is ensured by the arrangement of the racks and gears, and the fixed gear rack is mounted on each side frame juxtaposed to the vertically slidable member. The shaft spans the side frame and operates in bearings in each of the vertically slidable members. A gear is present at each end of the shaft and operates in mesh with the rack to produce the desired parallel movement.
[0030]
Except when engaging and stretching a material having a relatively high coefficient of friction, the drive of the CD mesh stretcher must operate both the upper and lower engaging rolls. However, the drive need not be antibacklash, since a small amount of longitudinal misalignment or drive slip will not cause problems. The reason for this will be clear from the description of the CD meshing element.
[0031]
The CD engaging element is machined from a solid material, but can best be described as an alternating stack of two different diameter disks. In a preferred embodiment, the interlocking discs are 6 inches in diameter, 0.031 inches in thickness, and have their edges perfectly rounded. The spacer disk sandwiched between the interlocking disks would be 51/2 inches in diameter and 0.069 inches thick. Two rolls of this configuration could be mated to 0.231 inches, leaving 0.019 inches of clearance for material on all sides. As with the diagonal meshing stretcher, this CD meshing element configuration will have a pitch of 0.100 inches.
[0032]
3.Longitudinal mesh stretching machine
The MD mesh stretching apparatus is the same as diagonal mesh stretching except for the design of the mesh roll. MD meshing rolls are very similar to fine pitch spur gears. In a preferred embodiment, the roll has a diameter of 5.935 inches, a pitch of 0.100 inches, a diameter pitch of 30, a pressure angle of 141/2 °, and is essentially a long tip gear. . A second pass was made on these rolls with a gear hob offset of 0.010 inches to provide narrowed teeth with greater clearance. With an engagement of about 0.090 inches, this configuration would have about 0.010 inches of clearance at the sides for material thickness.
[0033]
4.Incremental stretching technology
The diagonal, CD or MD interlocking stretcher described above is used to produce an incrementally stretched film or laminate of a nonwoven fibrous web and a microporous forming film to form the microporous film product of the present invention. May be done. For example, a drawing operation may be used for extrusion lamination of a nonwoven fibrous web of staple fibers or spunbonded filaments with a microporous forming thermoplastic film. In one unique aspect of the present invention, a nonwoven fibrous web laminate of spunbonded filaments may be incrementally drawn to provide a very soft fibrous end product in a fabric-like laminate. Good. Laminating the nonwoven fibrous web with the microporous forming film may be performed using a CD and / or MD interlocking stretcher at a speed of about 550 fpm to 1200 fpm or faster at about 0.060 inch to 0.120 inch. The film is gradually stretched once by passing through a stretching machine at a roller engagement depth of. The result of such incremental or intermeshing stretching produces a laminate that has excellent breathability and liquid barrier properties while providing excellent bond strength and a soft, cloth-like texture.
[0034]
The following examples illustrate the method of making the microporous films and laminates of the present invention. It will be apparent to those skilled in the art that, in light of these embodiments and further details, variations thereof are possible without departing from the scope of the invention.
[0035]
Examples 1A and 1B
In these examples, biodegradable copolyesters of the aromatic-aliphatic type are used as fully described in the examples of WO 98/23673. More specifically, films having representative biodegradable copolyesters described in the examples of this publication, containing from about 25% to about 40% zeolite or calcium carbonate, are commonly known in the art. Extruded by using a slot die casting film extrusion technique. In particular, a film having a thickness of about 2 mils (50 g / m²) Is extruded at a melting temperature on the order of about 425F to 475F. A micrograph of such a film surface is shown in FIG. 1 and a cross section is shown in FIG. This film was tested and found not to be air permeable, but 939 g / m2 according to ASTM E96E test method.²/ Day MVTR (moisture vapor permeability).
[0036]
The film of Example 1A became air permeable and increased moisture vapor permeability when stretched at about 72 ° F. in the above apparatus with a CD engagement of 0.070 inches and a subsequent MD engagement of 0.050 inches at about 72 ° F. It had. MVTR is 939 g / m²/ Day (Example 1A) to 2350 g / m²/ Day (Example 1B). The air permeability of the film, which originally had zero breathability (Example 1A), is 570 cc air / cm at 90 psi air pressure.²/ Min (Example 1B).
[0037]
Photomicrographs of the film surface and cross section of Examples 1A and 1B show that the inorganic particles are embedded (see FIGS. 1-5). The high MVTR and air permeable biodegradable films of the present invention had pore formation around the inorganic particles with increasing stretching (see FIGS. 4 and 5). Also, the non-stretched area did not show pore formation (see FIG. 3). The cross section of the Example 1B film (see FIG. 5) clearly showed that the pores were connected and allowed air to flow. The Example 1A film (see cross-section in FIG. 2) had no pore communication to allow air to flow therethrough.
[0038]
The mechanical properties of the Example 1A film are as follows:

[0039]
The biodegradable film of Example 1B requires a diaper where air flow (ventilation), high moisture vapor transmission, and liquid barrier properties are required for skin care and comfort during wear Suitable for backing sheets, sanitary napkins, and healthcare clothing applications.
[0040]
Examples 2A to 2H
In these examples, an aromatic-aliphatic type copolyester as used in Example 1A is extruded in a similar manner into a film. These films of Examples 2A-2H are CD and / or MD stretched at room temperature into air and moisture vapor permeable biodegradable films as shown below.
[0041]

[0042]
Other biodegradable polymers, such as polylactide, polycaprolactone, starch, polyvinyl alcohol, polyester, and copolyester, are processed with inorganic filler particles to provide an air and moisture permeable film in view of the above. be able to.
[0043]
In light of the above description, it will be understood that variations will occur depending on the materials and conditions using the principles of the present invention, as will be appreciated by those skilled in the art.
[Brief description of the drawings]
FIG.
It is a microscope photograph of 1000 times of the film surface of Example 1A.
FIG. 2
It is the microscope photograph at 2000 magnification of the cross section of the film of Example 1A.
FIG. 3
4 is a photomicrograph at 1000 × magnification of a non-stretched region due to meshing on the film surface of Example 1B.
FIG. 4
4 is a micrograph at 1000 × magnification of a stretched region of the film surface of Example 1B by meshing stretching.
FIG. 5
FIG. 4 is a micrograph at 2000 magnification of a cross section passing through a stretched surface region of the film of Example 1B.

Claims (21)

An air and moisture permeable biodegradable film comprising a biodegradable thermoplastic polymer containing a dispersed phase of inorganic filler particles,
Stretching region imparting microporous structure in the film having about 1000 g / ^{m 2} / day greater than the moisture vapor permeability MVTR and 90psi air pressure of about 30 cc / cm ² / min greater than the air permeability according to ASTM E96E The film having a liquid impervious thickness having: The film of claim 1, wherein the biodegradable thermoplastic polymer is selected from the group consisting of polycaprolactone, starch, polyvinyl alcohol, polylactide, polyester, and copolyester, and mixtures thereof. The film of claim 1, wherein the filler is selected from the group consisting of calcium carbonate, silica, talc, barium sulfate, zeolite, and mica, and mixtures thereof. The film of claim 1 laminated to a biodegradable fibrous web. The fibers of the fibrous web are cellulosic polymers, polyesters, copolyesters, completely L-lactic acid polymers, completely D-lactic acid polymers, L-lactic acid and D-lactic acid copolymers, and blends of L-lactic acid and D-lactic acid polymers. 5. The film of claim 4, wherein the film is selected from the group consisting of: The biodegradable fibrous polymer is polyvinyl alcohol (PVA), polycaprolactone (PCL), polylactide (PLA), starch, a blend of starch with PVA, PCL or PLA, polyhydroxy (butyrate) (PHB), polyhydroxy (valerate) 2.) The film of claim 1, wherein the film is selected from the group consisting of: (PHV), and aliphatic-aromatic copolymers, and mixtures thereof. The film of claim 1, wherein the microporous film has a thickness on the order of about 0.25 to about 10 mils. The film of claim 1, wherein the microporous film has a thickness on the order of about 0.25 to about 2 mils. Moisture vapor permeability (MVTR) is about 2000 to about 4500 g / ^{m 2} / day in accordance with ASTM E96E, and air permeability of about 200 to about 1600 cc / min / cm ² at 90psi air pressure, claim 1 Film. The film of claim 1, wherein said inorganic filler is selected from the group consisting of calcium carbonate, barium sulfate, mica, talc, silica and zeolite. A high speed method for producing air and moisture permeable biodegradable thermoplastic films having liquid barrier properties, comprising:
Melt blending about 40 to about 75% by weight of the biodegradable thermoplastic polymer and about 25 to about 60% by weight of the inorganic filler particles to form a biodegradable thermoplastic polymer composition;
Extruding a web of the molten thermoplastic composition from a slot die through a cooling zone into a nip of a roller to produce a film having a thickness of about 0.25 to about 10 mils at least about 550 fpm without resonance phenomena. Forming at a speed on the order of about 1200 fpm;
An MVTR and 90 psi air pressure greater than about 1000 g / m ² / day according to ASTM E96E applying an increasing stretching force to the film at a speed along a line substantially and uniformly across the film and through its depth. Providing a biodegradable microporous film having an air permeability greater than about 30 cc / cm ² / min.
The method comprising: MVTR is in the order of about 2000 to about 4500 g / ^{m 2} / day in accordance with ASTM E96E, and air permeability of about 200 to about 1600 cc / min / cm ² at 90psi air pressure, The method of claim 11. Directing a biodegradable nonwoven fibrous web into the roller nip and controlling the compression force to bond the web to the film and stretch to form a laminated biodegradable film. Item 11. The method according to Item 11. The method of claim 11, wherein the biodegradable thermoplastic polymer is selected from the group consisting of polycaprolactone, starch, polyvinyl alcohol, polylactide, polyester, copolyester, and mixtures thereof. The method of claim 11, wherein the filler is selected from the group consisting of calcium carbonate, silica, talc, barium sulfate, zeolites, and mica, and mixtures thereof. The fibers of the fibrous web are cellulosic polymers, polyesters, copolyesters, completely L-lactic acid polymers, completely D-lactic acid polymers, L-lactic acid and D-lactic acid copolymers, and blends of L-lactic acid and D-lactic acid polymers. The method of claim 11, wherein the method is selected from the group consisting of: The biodegradable thermoplastic polymer is polyvinyl alcohol (PVA), polycaprolactone (PCL), polylactide (PLA), starch, a blend of starch with PVA, PCL or PLA, polyhydroxy (butyrate) (PHB), polyhydroxy (valerate) 12. The method of claim 11, wherein the method is selected from the group consisting of: (PHV), and aliphatic-aromatic copolymers, and mixtures thereof. The method of claim 11, wherein the microporous film has a thickness on the order of about 0.25 to about 10 mils. The method of claim 11, wherein the microporous film has a thickness on the order of about 0.25 to about 2 mils. Moisture vapor permeability (MVTR) is on the order of about 2000 to about 4500 g / ^{m 2} / day according to ASTM E96E, The method of claim 11. 12. The method of claim 11, wherein said inorganic filler has an average particle size of about 1 to about 10 microns and is selected from the group consisting of calcium carbonate, barium sulfate, silica and zeolite.