Polyolefin-based microporous film by continuous cold stretching and hot stretching of an annealed polypropylene copolymer film

Abstract

A microporous polymeric film and method for making the same are disclosed, the microporous polymeric film comprising: (a) (i) 50 to 95 weight percent polypropylene copolymer, comprising 50 to 82 weight percent total polypropylene homopolymer chain segments, and (ii) 18 to 50 weight percent total ethylene-containing copolymer chain segments, at least a portion of which contain polymerized units of ethylene in an amount of at least 45 weight percent, and (b) 5 to 50 weight percent ethylene-propylene elastomer, at least 45 weight percent of the polymerized units in the ethylene-propylene elastomer are ethylene units.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to microporous films and the application of microporous films in various end uses such as housewraps, roof membranes, active and medical packaging, and sanitary and medical articles.

[0002] The present invention provides a microporous polymer film derived from a specific polypropylene (PP) copolymer comprising polypropylene homopolymer chain segments and ethylene-containing copolymer chain segments. The PP copolymer microporous films disclosed herein are produced without using conventional means to achieve porosity, i.e., without the use of void-forming inorganic fillers, perforations, or extensive pre-annealing to produce a good crystalline morphology as is carried out with homopolymer polyolefins. Instead, film porosity is achieved by a continuous cold / hot stretching process that results in pore formation induced by microphase separation in a specific type of PP copolymer used to produce a non-porous film, followed by pore formation in the polyolefin-based film disclosed herein. One advantageous feature of the methods disclosed herein is that the non-porous film does not require an annealing step prior to the cold / hot stretching process and does not require a heat curing or annealing step after the cold / hot stretching process.

[0003] This specification describes compositions of PP copolymers and process steps and methods for manufacturing and using their microporous films. In particular, these microporous films can be manufactured to provide water vapor permeability while maintaining an effective barrier against liquid water, and these permeabilities are adjustable. The property balance of the microporous films disclosed herein suggests that these films can find use in applications such as housewraps, roof membranes, and sanitary and medical articles, packaging (including active and medical packaging), and filtration.

Background Art

[0004] A microporous film, a method for manufacturing the same, and its use are described herein. The present invention provides a cost-effective and environmentally gentle manner of creating a microporous structure in a polyolefin-based film by an extrusion film casting / blown film and dry stretching process. The pore size and porosity of these microporous films can be adjusted to achieve optimized performance in various end-use applications (for example, for applications in housewraps, the film can be manufactured to have porosity and permeability characteristics equivalent to those of commercially available products such as Tyvek® housewrap from DuPont de Nemours, Inc., Wilmington, DE, USA). Alternatively, a smaller pore size can provide a barrier against air moving through the wall. According to the US Department of Energy, up to 40% of the energy consumed to heat or cool a building is lost due to air leakage.

[0005] Various end-use applications require or at least benefit from the use of breathable films. A breathable film can be described as a film that is relatively permeable to water vapor and relatively impermeable to liquids.

[0006] A housewrap functions as a weather barrier, preventing rain from entering the wall assembly while allowing water vapor to pass to the outside. Thus, for a housewrap to be effective, it must be water-repellent and have a high water vapor transmission rate (permeability). Currently, housewraps can be classified into two categories: woven and perforated, and non-woven and non-perforated. Generally less expensive perforated wraps are made from polyethylene or polypropylene that has been micro-perforated to be permeable, while non-perforated wraps consist of a polyolefin layer that allows water vapor to pass through its non-woven fiber mesh. Current technology generally involves multiple steps in the manufacturing process.

[0007] In addition, the present invention provides a polyolefin-based microporous film for roof membrane applications. There is a large market need for breathable roof membranes. Current non-permeable roof membranes made from polyvinyl chloride (PVC), thermoplastic polyolefin (TPO) or polymerized ethylene propylene diene monomer (EPDM) cannot meet this need, and polyolefin-based microporous films offer an opportunity to provide a low-cost alternative with high water vapor permeability compared to such current ones. The low / small water vapor permeability of current roof membranes leads to water accumulation under the roof membrane, which over time causes delamination of the roof membrane from the roof (e.g., lightweight concrete structures), and then damage to the roof structure. The higher water vapor permeability of thick polyolefin-based microporous films meets important requirements for roof membranes, such as high moisture vapor permeability (permeability), e.g., 10 perm or more; and good water repellency (weather barrier). The weather resistance of polyolefin-based microporous films can be further enhanced by applying anti-UV agents.

[0008] Polyethylene films are widely used in sanitary absorption products such as diaper backsheets. Diaper backsheets can be classified as breathable or non-breathable. Breathable backsheets typically use films filled with more than 50 wt% CaCO3 (or other inorganic fillers) and / or micro-voided. However, due to the active competition in the sanitary absorption product market, film manufacturers are required to pursue differentiated technologies that enable enhanced product performance such as improved mechanical property performance while also making it possible to reduce costs, for example, from further down gauging (thinner films). SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] Accordingly, in many end-use markets, there is a need for an improved breathable film that has a very thin gauge, has a high porosity that allows for high water vapor transmission while preventing leakage of water, which is a liquid, and ensures good processability and mechanical properties. The non-interconnected micropores of the microporous films disclosed herein provide better barrier performance against air, water, bacteria, and blood, and such barrier performance is essential for applications such as housewrap, roofing membranes, air filtration, medical packaging, and medical backtable covers. Due to the relatively high melting temperature of the PP copolymer, its application in steam sterilization related to medical packaging is possible. Also, the wide range of adjustable breathability suggests that these microporous films are also possible for applications related to active packaging (sachets).

[0010] Furthermore, the tensile modulus of the film is related to the flexibility of the film, and furthermore, such films with a lower tensile modulus have the potential for improved toughness, installation by hot air welding, and low temperature durability, so microporous films containing PP copolymers with a lower tensile modulus are considered particularly desirable for some applications.

[0011] Accordingly, there is a need for compositions containing the polypropylene copolymer compositions described herein, microporous films made therefrom, methods for preparing them, and methods for using them. The present invention disclosed herein is directed to these and other important objectives and provides solutions to these market needs.

Means for Solving the Problems

[0012] In certain embodiments, the invention described herein comprises, consists of, or consists essentially of one or more polypropylene copolymers comprising one or more polypropylene homopolymer chain segments and one or more ethylene-containing copolymer chain segments, and the microporous polymer film comprises (i) polypropylene homopolymer chain segments in an amount of 50 to 82 wt% based on the weight of the microporous polymer film, or 43 to 79 mol% based on the molar content of the propylene polymerized units in the polypropylene homopolymer chain segments as a percentage of the total molar content of the polymerized monomer units in the microporous polymer film, and (ii) ethylene-containing copolymer chain segments in an amount of 18 to 50 wt% based on the weight of the microporous polymer film, or 21 to 57 mol% based on the molar content of the polymerized monomer units in the ethylene-containing copolymer chain segments as a percentage of the total molar content of the polymerized monomer units in the microporous polymer film, with at least a portion of the ethylene-containing copolymer chain segments comprising ethylene polymerized units in an amount of at least 45 wt% based on the weight of the ethylene-containing copolymer chain segments, or at least 55 mol% based on the molar content of the ethylene polymerized units in the ethylene-containing copolymer chain segments as a percentage of the total molar content of the polymerized monomer units in the ethylene-containing copolymer chain segments.

[0013] In one embodiment, a method of forming a microporous polymer film, the method steps comprising: (a) providing one or more polypropylene copolymers, wherein the one or more polypropylene copolymers comprise: (i) one or more polypropylene homopolymer chain segments, based on the weight of the polypropylene copolymer, from 50 to 82 wt%, or as a percentage of the total molar content of the polymerized monomer units in the polypropylene copolymer, based on the molar content of the polymerized propylene units in the polypropylene homopolymer chain segments, a total amount of from 43 to 79 mol%; and (ii) one or more ethylene-containing copolymer chain segments, based on the weight of the polypropylene copolymer, from 18 to 50 wt%, or as a percentage of the total molar content of the polymerized monomer units in the polypropylene copolymer, based on the molar content of the polymerized monomer units in the ethylene-containing copolymer chain segments, a total amount of from 21 to 57 mol%, wherein at least a portion of the ethylene-containing copolymer chain segments comprises ethylene polymerized units in an amount of at least 45 wt% based on the weight of the ethylene-containing copolymer chain segments, or at least 55 mol% based on the molar content of the ethylene polymerized units in the ethylene-containing copolymer chain segments as a percentage of the total molar content of the polymerized monomer units in the ethylene-containing copolymer chain segments; (b) forming a non-porous film from the polypropylene copolymer; and (c) subjecting the non-porous film to a continuous cold stretching and hot stretching step comprising: (i) at least one cold stretching step at a temperature in the range of -20°C to 50°C; and (ii) at least one hot stretching step at a temperature in the range of 50°C to 150°C, thereby producing a microporous polymer film. A method is disclosed that comprises, consists of, or consists essentially of the foregoing.

[0014] In some embodiments, the method is a continuous process for manufacturing a microporous polymer film. In particular, in some embodiments, the method proceeds without any annealing step after the formation of the non-porous film and without any annealing or thermosetting step after the formation of the microporous polymer film, and is a continuous process for manufacturing a microporous polymer film.

[0015] In another embodiment, the present invention relates to a microporous polymer film, which is: (a) one or more polypropylene copolymers that are 50 to 95 weight percent based on the total weight of the film, the polypropylene copolymer comprising one or more polypropylene homopolymer chain segments and one or more ethylene-containing copolymer chain segments; the microporous polymer film (i) a polypropylene homopolymer chain segment that is 50 to 82 weight percent based on the weight of the polypropylene copolymer or 43 to 79 mole percent based on the molar content of the propylene polymerization units in the polypropylene homopolymer chain segment as a percentage of the total molar content of the polymerization monomer units in the polypropylene copolymer, and (ii) an ethylene-containing copolymer chain segment that is 18 to 50 weight percent based on the weight of the polypropylene copolymer or 21 to 57 mole percent based on the molar content of the polymerization monomer units in the ethylene-containing copolymer chain segment as a percentage of the total molar content of the polymerization monomer units in the polypropylene copolymer, and including one or more polypropylene copolymers, wherein at least a portion of the ethylene-containing copolymer chain segment contains ethylene polymerization units in an amount of at least 55 mole percent based on the molar content of the ethylene polymerization units in the ethylene-containing copolymer chain segment, which is at least 45 weight percent based on the weight of the ethylene-containing copolymer chain segment or as a percentage of the total molar content of the polymerization monomer units in the ethylene-containing copolymer chain segment. (b) 5 to 50 weight percent, based on the total weight of the film, of one or more ethylene-propylene elastomers; (b) at least 45 weight percent of the polymerized units in the ethylene-propylene elastomer are units of ethylene.

[0016] In yet another alternative embodiment, the present invention further relates to a method of forming a microporous polymer film, the method steps comprising: A) providing a mixture, the mixture being (a) 50 to 95 weight percent, based on the total weight of the mixture, of one or more polypropylene copolymers: (i) one or more polypropylene homopolymer chain segments, 50 to 82 weight percent based on the weight of the polypropylene copolymer or as a percentage of the total molar content of the polymerized monomer units in the polypropylene copolymer, one or more polypropylene homopolymer chain segments in a total amount of 43 to 79 mol% based on the molar content of the polymerized propylene units in the polypropylene homopolymer chain segments, (ii) one or more ethylene-containing copolymer chain segments, 18 to 50 weight percent based on the weight of the polypropylene copolymer or as a percentage of the total molar content of the polymerized monomer units in the polypropylene copolymer, one or more ethylene-containing copolymer chain segments in a total amount of 21 to 57 mol% based on the molar content of the polymerized monomer units in the ethylene-containing copolymer chain segments, wherein at least a portion of the ethylene-containing copolymer chain segments contains polymerized units of ethylene in an amount of at least 55 mol% based on the molar content of the polymerized ethylene units in the ethylene-containing copolymer chain segments, 45 weight percent or more based on the weight of the ethylene-containing copolymer chain segments or as a percentage of the total molar content of the polymerized monomer units in the ethylene-containing copolymer chain segments, one or more polypropylene copolymers, (b) 5 to 50 weight percent, based on the total weight of the mixture, of one or more ethylene-propylene elastomers, a mixture of Providing a mixture in which at least 45 weight percent of the polymerized units in an ethylene-propylene elastomer are ethylene units; B) Forming a non-porous film from the mixture; and C) Subjecting the non-porous film to (i) at least one cold stretching step at a temperature in the range of -20 °C to 50 °C, and (ii) at least one hot stretching step at a temperature in the range of 50 °C to 140 °C in a continuous cold stretching and hot stretching step, thereby producing a microporous polymer film.

[0017] Included to provide a further understanding of the present invention, incorporated herein, and constituting a part of this specification, the accompanying drawings illustrate embodiments of the present invention and serve to explain the principles of the present invention together with the description.

Brief Description of the Drawings

[0018]

Figure 1A

Figure 1B

Figure 2A

Figure 2B

Figure 2C

Figure 3A

Figure 3B

Figure 3C

Figure 3D

Figure 4A

Figure 4B

Figure 4C

Figure 4D

Figure 5A

Figure 5B

Figure 5C

Figure 5D

Figure 6A

Figure 6B

Figure 7A

Figure 7B

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention can be more readily understood by reference to the following detailed description, examples, drawings, and claims, as well as the foregoing and following descriptions thereof. However, it is to be understood that the invention is not limited to the specific compositions, articles, devices, systems, and / or methods disclosed, unless otherwise specified, and can, of course, vary. Aspects of the present invention may be described and claimed in specific statutory classifications, such as composition of matter classifications, but this is for convenience only, and those skilled in the art will understand that each aspect of the present invention can be described and claimed in any statutory classification.

[0020] The following detailed description of the invention is also provided as a teaching enabling the best mode currently known of the invention. To achieve this objective, while various modifications and adaptations may be made to the various aspects of the invention described herein, those skilled in the art will recognize and understand that the beneficial results of the invention can still be obtained. It will also be understood that by selecting some of the features of the invention, a part of the benefits of the invention can be obtained without using other features. Accordingly, those skilled in the art will recognize that many modifications and adaptations are possible to the invention and that in certain circumstances, many such modifications and adaptations may be more desirable, and thus, many such modifications and adaptations are also part of the invention.

[0021] The present invention can be embodied in various forms, but the following description of some embodiments is made with the understanding that the present disclosure is regarded as an exemplification of the invention and is not intended to limit the invention to the specific embodiments illustrated. The headings are provided for convenience only and should in no way be construed as limiting the invention. The embodiments illustrated in any heading or any part of the present disclosure may be combined with the embodiments illustrated in the same or any other heading or other part of the present disclosure.

[0022] Any combination of the elements described herein in all its possible variations is included by the present invention unless otherwise specifically indicated herein or clearly contradicted by the context.

[0023] Unless otherwise expressly stated, no method or aspect described in this specification is ever intended to be construed as requiring that its steps be performed in a particular order. Accordingly, where a method claim does not specifically recite in the claims or description that the steps are limited to a particular order, no order should be inferred in any sense. This applies to any possible non-expression-based grounds for interpretation, including logical matters regarding step arrangement or operation flow, simple meanings derived from grammatical construction or punctuation, or the number or type of embodiments described in this specification. It should be understood that both the foregoing summary and the following detailed description are merely illustrative and explanatory and not restrictive.

[0024] All publications mentioned in this specification are hereby incorporated by reference herein for the purpose of disclosing and describing the methods and / or materials related to those cited in the publications.

[0025] It should be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. Many of the terms defined herein will be referred to in this specification and in the claims that follow.

[0026] As used in this specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise.

[0027] As used herein, the term "and / or" means "and or alternatively".

[0028] As used herein, the terms "optional" or "optionally" mean that the events, conditions, components or situations described hereinafter may or may not occur and that the description includes instances where the events, conditions, components or situations occur and instances where they do not occur.

[0029] Any disclosure using the terms "comprising" or "comprises" as used herein also includes similar disclosures, and instead, "comprising" or "comprises" is replaced by "consisting of" or "consists of", or instead, is replaced by "consisting essentially of" or "consists essentially of".

[0030] As used herein, the phrase "sufficient" (e.g., "conditions sufficient to ~") means such a value or condition that can fulfill the function or characteristic for the sufficient value or condition to be manifested. As pointed out below, the exact value or specific conditions required can vary from embodiment to embodiment depending on well-recognized variables such as the materials used and / or processing conditions.

[0031] The term "by weight", when used in combination with a component, unless otherwise specified, is based on the total weight of the formulation or composition in which the component is included. For example, when it is said that a particular element or component in a composition or article is present in an amount of 8 weight% (also written as 8 wt.%), this percentage is understood to relate to the total composition percentage of 100%. The weight% of component A in a composition is the weight of component A expressed as a percentage of the total weight of the composition and has conventionally been described as "weight% of A based on the total weight of the composition". In some examples, the weight percentage of a component indicates the weight of the "dry basis" composition, which is the total weight of the composition with no water (e.g., less than about 1 weight%, less than about 0.5 weight%, less than about 0.1 weight%, less than about 0.05 weight% or about 0 weight% water based on the total weight of the composition).

[0032] In this specification, when disclosing numerical values, such as numerical values 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc., the following sentence typically applies to such numerical values. "The foregoing numbers can each be used with the terms 'about', 'at least about', or 'about to less than', and any of the foregoing numbers can be used alone or in combination with the description of a limiting range to describe a non-limiting range." This sentence means that each of the foregoing numbers can be used alone (e.g., 4), can be preceded by the word 'about' (e.g., about 8), can be preceded by the phrase 'at least about' (e.g., at least about 2), can be preceded by the phrase 'about to less than' (e.g., less than about 7), or can be used arbitrarily in combination with or without any of the preceding words or phrases for defining a range (e.g., 2 - 9, about 1 - 4, 8 - about 9, about 1 - about 10, etc.). Further, when a range is described as 'about X or less', this phrase is the same as a range that is a combination of 'about X' and 'less than about X'. For example, 'about 10 or less' is the same as 'about 10 or less than about 10'. Such replaceable range descriptions are intended in this specification. Although other range forms are disclosed in this specification, differences in form should not be construed as implying differences in substance.

[0033] As used herein, "continuous" refers to a process whose period is continuous or interrupted, aborted, or stopped only instantaneously as compared to the period of the process. A process is "continuous" when the starting material or reactant is fed to the apparatus without interruption or substantially without interruption or when the processing of the starting material or reactant is not carried out in a batch process.

[0034] As used herein, the term "substantially free of" means a composition having less than about 1% by weight, e.g., less than about 0.5% by weight, less than about 0.1% by weight, less than about 0.05% by weight, or less than about 0.01% by weight of the indicated substance, based on the total weight of the composition.

[0035] As used herein, the term "substantially" when used with respect to a composition means at least about 60 weight percent, such as at least about 65 weight percent, at least about 70 weight percent, at least about 75 weight percent, at least about 80 weight percent, at least about 85 weight percent, at least about 90 weight percent, at least about 91 weight percent, at least about 92 weight percent, at least about 93 weight percent, at least about 94 weight percent, at least about 95 weight percent, at least about 96 weight percent, at least about 97 weight percent, at least about 98 weight percent, at least about 99 weight percent or about 100 weight percent of a particular feature or component, based on the total weight of the composition.

[0036] All molecular weights and other values related to molecular weight disclosed herein (e.g., polydispersity index, etc.) are measured by gel permeation chromatography (GPC).

[0037] As used herein, the terms "molar mass distribution", "MMD" and "molecular weight distribution" are used interchangeably and describe the relationship between the number of moles or number of polymer chains (N i ) of each polymer species and the molar mass (M i ) of that species or between polymer chains. The molar mass distribution of a polymer may be altered by polymer fractions. Depending on the statistical method applied, different average values may be defined and are described herein.

[0038] As used herein, the term "number average molecular weight" (M n , or

Number

Number

[0039] As used herein, the term "weight average molecular weight" (Mw, or [Number] ) is defined by the following formula: [Number] wherein M i is the molecular weight of the chain and N i is the number of chains of that molecular weight. Compared to M n , M w considers the molecular weight of a given chain to determine its contribution to the molecular weight average. Thus, the larger the molecular weight of a given chain, the greater its contribution to M w of the chain. M w can be determined for a polymer by methods well known to those skilled in the art using a molecular weight standard, such as a polystyrene standard, preferably a certified or traceable molecular weight standard.

[0040] As used herein, gel permeation chromatography (GPC) refers to a chromatographic separation method in which molecules in solution are separated by their size. The separation is achieved by differential exclusion of the sample molecules as they pass through a layer of porous particles known as a separation column. GPC can be used to determine the substantially exact molar mass distribution of polymer molecules. For example, a liquid fraction (eluent) that has passed through the column is collected in a fixed amount. Since the polymer elutes through the column, molecules that are too large to pass through the pores of the column are excluded from the packed pore volume and elute with an earlier retention time, while smaller molecules enter the pores of the column and elute at a later time. The concentration of the eluted polymer can be measured by spectroscopic techniques such as, for example, refractive index (RI) and ultraviolet light (UV). The flow of the eluent can also be continuously analyzed by RI, low angle laser light scattering (LALLS), multi-angle laser scattering (MALLS), UV, and / or viscosity measurement.

[0041] The use of numerical values in the various quantitative values specified in this application is described as an approximate value as if both the minimum and maximum values within the specified range were preceded by the word "about", unless specifically indicated otherwise. Thus, minor differences from the indicated values can be used to achieve substantially the same results as the indicated values. Also, the disclosure of a range is intended to cover a continuous range including all values between the recited minimum and maximum values and any range that can be formed by such values. Also, any and all ratios (and any range of such ratios) that can be formed by dividing the recited numerical values by any other recited numerical value are also disclosed herein. Accordingly, those skilled in the art will understand that many such ratios, ranges, and ranges of ratios can be clearly derived from the numerical values presented herein, and in all instances, such ratios, ranges, and ranges of ratios represent various embodiments of the invention.

[0042] As used herein, "average pore diameter" refers to the "average pore size" measured by mercury intrusion porosimetry (4V / A according to UOP method 578-11 described below), which is known to those skilled in the art or is known in the field of mercury intrusion porosimetry. The UOP method is available from ASTM International, West Conshohocken, PA, USA (or via www.astm.org). Since the average is the median average, this term may be described herein as the "median pore size".

[0043] As used herein, the term "polypropylene copolymer" means a copolymer containing a polymer main chain, side chain or chain segment of polypropylene, and in particular, such a main chain, side chain or chain segment contains 15 or more consecutive polymerization units of propylene. As disclosed herein, preferred PP copolymers contain polypropylene homopolymer chain segments (e.g., isotactic PP) and ethylene-containing copolymer chain segments. In some embodiments, the ethylene-containing copolymer chain segment is an ethylene-propylene (EP) copolymer chain segment, and such a polypropylene copolymer may be described herein as a PP-EP copolymer.

[0044] In some embodiments, the present invention relates to a microporous polymer film comprising one or more polypropylene copolymers (PP copolymers). The PP copolymer may contain one or more polypropylene homopolymer chain segments and one or more ethylene-containing copolymer chain segments.

[0045] In some embodiments, the PP copolymer comprises polypropylene homopolymer chain segments in an amount of at least about 50 wt% based on the total weight of the PP copolymer, and the maximum amount of the polypropylene homopolymer chain segments is not particularly limited. In the same or other embodiments, the PP copolymer comprises polypropylene homopolymer chain segments in an amount of up to about 95 wt% based on the total weight of the PP copolymer, and the minimum amount of the polypropylene homopolymer chain segments is not particularly limited. For example, the PP copolymer can comprise polypropylene homopolymer chain segments in an amount of 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 65, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 95% (by weight based on the weight of the PP copolymer). Each of the foregoing numbers can be preceded by the words "about," "at least about," or "less than about," and any of the foregoing numbers can be used alone or in combination to describe a non-limiting range or to describe a limiting range. For example, but not limited to, the amount of polypropylene homopolymer chain segments in the PP copolymer can be at least about 50 wt%, about 50 wt% to about 82 wt%, or about 60 wt% to about 82% by weight based on the total weight of the PP copolymer. From the perspective of mol%, the PP copolymer can comprise polypropylene homopolymer chain segments in an amount of 40, 42, 43, 44, 45, 46, 47, 48, 49, 50, 52, 54, 55, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 79, 80, 82, or 85% (in mol% based on the molar content of the propylene polymerization units in the polypropylene homopolymer chain segments as a percentage of the total molar content of the polymerization monomer units in the PP copolymer). Each of the foregoing numbers can be preceded by the words "about," "at least about," or "less than about," and any of the foregoing numbers can be used alone or in combination to describe a non-limiting range or to describe a limiting range.For example, but not limited to, the amount of polypropylene homopolymer chain segments in the PP copolymer can be at least about 43 mol%, about 43 mol% to about 79 mol% or about 50 mol% to about 79 mol% based on the molar content of the propylene polymerization units in the polypropylene homopolymer chain segments as a percentage of the total molar content of the polymerization monomer units in the PP copolymer.

[0046] In some embodiments, the PP copolymer comprises ethylene-containing copolymer chain segments in an amount of at least about 5 wt% based on the total weight of the PP copolymer, and the maximum amount of the ethylene-containing copolymer chain segments is not particularly limited. In the same or other embodiments, the PP copolymer comprises ethylene-containing copolymer chain segments in an amount up to about 50 wt% based on the total weight of the PP copolymer, and the minimum amount of the ethylene-containing copolymer chain segments is not particularly limited. For example, the PP copolymer may comprise ethylene-containing copolymer chain segments in an amount of 5, 10, 15, 17, 18, 19, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54 or 55% (by weight based on the weight of the PP copolymer). Each of the foregoing numbers may be preceded by the words "about", "at least about" or "less than about", and any of the foregoing numbers may be used alone or in combination to describe a non-limiting range or to describe a limiting range. For example, but not limited to, the amount of ethylene-containing copolymer chain segments in the PP copolymer may be at least about 10 wt%, about 18 wt% to about 50 wt% or about 25 wt% to about 40 wt% by weight based on the total weight of the PP copolymer. Preferably, the ethylene-containing copolymer chain segments in the PP copolymer are ethylene-propylene (EP) copolymer chain segments. From the perspective of mol%, the PP copolymer may comprise ethylene-containing copolymer chain segments in an amount of 10, 15, 17, 18, 19, 20, 21, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 55%, 57 or 60% (in mol% based on the molar content of the polymerized monomer units in the ethylene-containing copolymer chain segments as a percentage of the total molar content of the polymerized monomer units in the PP copolymer). Each of the foregoing numbers may be preceded by the words "about", "at least about" or "less than about", and any of the foregoing numbers may be used alone or in combination to describe a non-limiting range or to describe a limiting range.For example, but not limited to, the amount of ethylene-containing copolymer chain segments in the PP copolymer can be at least about 15 mol%, about 21 mol% to about 57 mol% or about 21 mol% to about 45 mol% based on the molar content of the polymerized monomer units in the ethylene-containing copolymer chain segments, as a percentage of the total molar content of the polymerized monomer units in the PP copolymer.

[0047] In some embodiments, the ethylene-containing copolymer chain segment in the PP copolymer comprises at least 45 wt% of ethylene polymerization units based on the total weight of the ethylene-containing copolymer chain segment, and the maximum amount of ethylene in the ethylene-containing copolymer chain segment is not particularly limited. For example, the ethylene unit content in the ethylene-containing copolymer chain segment in the PP copolymer can be an amount in wt% (based on the weight of the ethylene-containing copolymer chain segment) of 40, 42, 44, 45, 46, 47, 48, 49, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 75 or 80%. Each of the foregoing numbers can be preceded by the words "about", "at least about" or "less than about", and any of the foregoing numbers can be used alone or in combination to describe a non-limiting range or to describe a limiting range. For example, but not limited to, the amount of ethylene units in the ethylene-containing copolymer chain segment in the PP copolymer can be at least about 45 wt%, about 45 wt% to about 80 wt% or about 45 wt% to about 60 wt% based on the total weight of the ethylene-containing copolymer chain segment. From the perspective of mol%, the ethylene unit content in the ethylene-containing copolymer chain segment in the PP copolymer can be an amount in mol% (as a percentage of the total molar content of the polymerized monomer units in the ethylene-containing copolymer chain segment) of 50, 52, 54, 55, 56, 57, 58, 59, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 85 or 90%. Each of the foregoing numbers can be preceded by the words "about", "at least about" or "less than about", and any of the foregoing numbers can be used alone or in combination to describe a non-limiting range or to describe a limiting range. For example, but not limited to, the amount of ethylene units in the ethylene-containing copolymer chain segment in the PP copolymer can be at least about 55 mol%, about 55 mol% to about 80 mol% or about 55 mol% to about 69 mol% based on the molar content of the ethylene polymerization units in the ethylene-containing copolymer chain segment as a percentage of the total molar content of the polymerized monomer units in the ethylene-containing copolymer chain segment.Preferably, the ethylene-containing copolymer chain segments in the PP copolymer are ethylene-propylene (EP) copolymer chain segments, in which case the above percentages refer to the ethylene unit content % (either weight % or molar % as described above) in the EP copolymer chain segments.

[0048] The total ethylene content in the polymerization form in the PP copolymer is at least 10% by weight, such as 10 to 30% by weight or more preferably 15 to 25% by weight based on the weight of the PP copolymer, or as a percentage of the total molar content of the polymerization monomer units in the PP copolymer, at least 14 mol%, such as 14 to 39 mol% or 15 to 25 mol% based on the molar content of the polymerized units of ethylene in the PP copolymer.

[0049] The microporous polymer film can essentially consist of one or more polypropylene copolymers (PP copolymers) containing one or more polypropylene homopolymer chain segments and one or more ethylene-containing copolymer chain segments. Thus, in at least some embodiments, the same amounts and ranges as outlined above for the polypropylene homopolymer chain segments and ethylene-containing copolymer chain segments in the PP copolymer are also appropriate for the amounts and ranges of the polypropylene homopolymer chain segments and ethylene-containing copolymer chain segments in the microporous polymer film.

[0050] In some embodiments, the microporous polymer film comprises at least about 50 wt% of polypropylene homopolymer chain segments, based on the total weight of the microporous polymer film, and the maximum amount of polypropylene homopolymer chain segments is not particularly limited. In the same or other embodiments, the microporous polymer film comprises up to about 95 wt% of polypropylene homopolymer chain segments, based on the total weight of the microporous polymer film, and the minimum amount of polypropylene homopolymer chain segments is not particularly limited. For example, the microporous polymer film may comprise polypropylene homopolymer chain segments in an amount of 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88%, 90%, 95% (by weight based on the weight of the microporous polymer film). Each of the foregoing numbers may be preceded by the words "about," "at least about," or "less than about," and any of the foregoing numbers may be used alone or in combination to describe a non-limiting range or to describe a limiting range. For example, without limitation, the amount of polypropylene homopolymer chain segments in the microporous polymer film may be at least about 50 wt%, about 50 wt% to about 82 wt%, or about 60 wt% to about 82 wt%, based on the total weight of the microporous polymer film. From the perspective of mol%, the microporous polymer film may comprise polypropylene homopolymer chain segments in an amount of 40, 42, 43, 44, 45, 46, 47, 48, 49, 50, 52, 54, 55, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 79, 80, 82, or 85% (mol% based on the molar content of propylene polymerization units in the polypropylene homopolymer chain segments as a percentage of the total molar content of polymerization monomer units in the microporous polymer film). Each of the foregoing numbers may be preceded by the words "about," "at least about," or "less than about," and any of the foregoing numbers may be used alone or in combination to describe a non-limiting range or to describe a limiting range.For example, but not limited to, the amount of polypropylene homopolymer chain segments in the microporous polymer film can be at least about 43 mol%, about 43 mol% to about 79 mol%, or about 50 mol% to about 80 mol%, based on the molar content of the polymerized propylene units in the polypropylene homopolymer chain segments, as a percentage of the total molar content of the polymerized monomer units in the microporous polymer film.

[0051] The polypropylene homopolymer chain segments present in the microporous polymer film can be derived solely from the PP copolymer component or can be a combination of polypropylene homopolymer chain segments derived from the PP copolymer component and one or more other polymer components (PP homopolymer or another copolymer containing polypropylene homopolymer chain segments) containing polypropylene homopolymer chain segments. Preferably, the polypropylene homopolymer chain segments present in the microporous polymer film are derived solely from the PP copolymer component.

[0052] In some embodiments, the microporous polymer film comprises ethylene-containing copolymer chain segments in an amount of at least about 5 wt% based on the total weight of the microporous polymer film, and the maximum amount of the ethylene-containing copolymer chain segments is not particularly limited. In the same or other embodiments, the microporous polymer film comprises ethylene-containing copolymer chain segments in an amount of up to about 60 wt% based on the total weight of the microporous polymer film, and the minimum amount of the ethylene-containing copolymer chain segments is not particularly limited. For example, the microporous polymer film may comprise ethylene-containing copolymer chain segments in an amount of 5, 10, 15, 17, 18, 19, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 55, 56, 58 or 60% (by weight based on the weight of the microporous polymer film). Each of the foregoing numbers may be preceded by the words "about", "at least about" or "less than about", and any of the foregoing numbers may be used alone or in combination to describe a non-limiting range or to describe a limiting range. For example, but not limited to, the amount of ethylene-containing copolymer chain segments in the microporous polymer film may be at least about 10 wt%, about 18 wt% to about 50 wt% or about 25 wt% to about 40 wt% based on the total weight of the microporous polymer film. From the perspective of mol%, the microporous polymer film may comprise ethylene-containing copolymer chain segments in an amount of 10, 15, 17, 18, 19, 20, 21, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 55, 57 or 60% (in mol% based on the molar content of the polymerized monomer units in the ethylene-containing copolymer chain segments as a percentage of the total molar content of the polymerized monomer units in the microporous polymer film). Each of the foregoing numbers may be preceded by the words "about", "at least about" or "less than about", and any of the foregoing numbers may be used alone or in combination to describe a non-limiting range or to describe a limiting range.For example, but not limited to, the amount of ethylene-containing copolymer chain segments in the microporous polymer film can be at least about 15 mol%, about 21 mol% to about 57 mol% or about 20 mol% to about 45 mol% based on the molar content of the polymer monomer units in the microporous polymer film as a percentage of the total molar content of the polymer monomer units in the ethylene-containing copolymer chain segments.

[0053] The ethylene-containing copolymer chain segments present in the microporous polymer film can be derived from only the PP copolymer component or a combination of the PP copolymer component and ethylene-containing copolymer chain segments derived from one or more other polymer components (e.g., EP copolymer) containing ethylene-containing copolymer chain segments. Preferably, the ethylene-containing copolymer chain segments present in the microporous polymer film are derived from only the PP copolymer component. Preferably, the ethylene-containing copolymer chain segments are ethylene-propylene (EP) copolymer chain segments.

[0054] In some embodiments, the ethylene-containing copolymer chain segments in the microporous polymer film comprise at least 45 wt% of ethylene polymerization units, based on the total weight of the ethylene-containing copolymer chain segments, and the maximum amount of ethylene in the ethylene-containing copolymer chain segments is not particularly limited. For example, the ethylene unit content in the ethylene-containing copolymer chain segments in the microporous polymer film can be an amount in % by weight (based on the weight of the ethylene-containing copolymer chain segments) of 40, 42, 44, 45, 46, 47, 48, 49, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 75 or 80%. Each of the foregoing numbers can be preceded by the words "about", "at least about" or "less than about", and any of the foregoing numbers can be used alone or in combination to describe a non-limiting range or a limiting range. For example, without limitation, the amount of ethylene units in the ethylene-containing copolymer chain segments in the microporous polymer film can be at least about 45 wt%, about 45 wt% to about 80 wt% or about 45 wt% to about 60 wt%, based on the total weight of the ethylene-containing copolymer chain segments. From the perspective of mol%, the ethylene unit content in the ethylene-containing copolymer chain segments in the microporous polymer film can be an amount in mol% (as a percentage of the total molar content of the polymerized monomer units in the ethylene-containing copolymer chain segments) of 50, 52, 54, 55, 56, 57, 58, 59, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 85 or 90%. Each of the foregoing numbers can be preceded by the words "about", "at least about" or "less than about", and any of the foregoing numbers can be used alone or in combination to describe a non-limiting range or a limiting range.For example, but not limited to, the amount of ethylene units in the ethylene-containing copolymer chain segments in the microporous polymer film is at least about 55 mol%, about 55 mol% to about 80 mol%, or about 55 mol% to about 69 mol% based on the molar content of the polymerized monomer units in the ethylene-containing copolymer chain segments as a percentage of the total molar content of the polymerized monomer units in the ethylene-containing copolymer chain segments. Preferably, the ethylene-containing copolymer chain segments in the PP copolymer are ethylene-propylene (EP) copolymer chain segments, in which case the above percentage refers to the ethylene unit content% (either weight% or mol% as described above) in the EP copolymer chain segments.

[0055] The total ethylene content of the polymerization form in the microporous polymer film is at least 10 wt%, such as, for example, 10 to 30 wt% or more preferably 15 to 25 wt% based on the weight of the microporous polymer film, or at least 14 mol%, such as, for example, 14 to 39 mol%, or 15 to 25 mol%, or 21 to 33 mol% based on the molar content of the polymerized ethylene units in the microporous polymer film as a percentage of the total molar content of the polymerized monomer units in the microporous polymer film.

[0056] In certain embodiments, these PP copolymers can be produced in a reactor from one or more components of a PP homopolymer and one or more components of an ethylene-containing copolymer. Preferably, the ethylene-containing copolymer is an ethylene-propylene (EP) copolymer. Accordingly, the present invention provides a microporous polymer film comprising a polypropylene copolymer produced from the reaction product of a polypropylene homopolymer and an ethylene-propylene copolymer.

[0057] In certain embodiments where the ethylene-containing copolymer is an ethylene-propylene (EP) copolymer, the microporous film can consist essentially of a PP-EP copolymer comprising one or more polypropylene homopolymer chain segments and one or more ethylene-propylene copolymer chain segments. In certain such embodiments, the weight ratio of the PP component to the EP component can be 50:50, 55:45, 60:40, 65:35, 67:33, 70:30, 72:28, 74:26, 76:24, 78:22, 79:21, 80:20, 81:19, 82:18, 84:16, 86:14, 88:12, 90:10 or 95:5. Each of the foregoing numbers can be preceded by the words "about", "at least about" or "about - less than", and any of the foregoing numbers can be used alone or in combination to describe a non-limiting range or to describe a limiting range. For example, the weight ratio can be at least about 60:40, about 65:35 to about 85:15 or less than about 90:10.

[0058] The ethylene-containing copolymer can be a random copolymer, an alternating copolymer or a block copolymer, and the ethylene-propylene copolymer can be a random EP copolymer, an alternating EP copolymer or an EP block copolymer. For example, a PP copolymer containing an EP copolymer main chain or chain segment can contain a random EP copolymer main chain or chain segment, an alternating EP copolymer main chain or chain segment or a diblock copolymer main chain or chain segment. For example, a diblock copolymer can contain a polypropylene block and a polyethylene block, or a polypropylene block and an EP copolymer block, or a polyethylene block and an EP copolymer block. Other ethylene-containing copolymers can also be used.

[0059] The film can be produced from a PP copolymer or a polymer blend thereof by heating it to a temperature sufficient to obtain the PP copolymer (or blend thereof) in a molten form, most conveniently by any method known in the art, followed by extrusion or inflation molding. In some embodiments, the film can be a multilayer film. The multilayer film can be coextruded, whereby a first layer is coextruded with a second layer.

[0060] Prior to stretching, the non-porous polymer film can have a morphology characterized by a majority polypropylene phase (or matrix) in the polymer film, a minority polymer region of an ethylene-containing copolymer such as an ethylene-propylene copolymer region, and an inclusion phase of the major polypropylene phase in the minority polymer region. This enables effective transfer of the stretching force from the major phase to the minority regions, causing the minority regions to be divided and then micropores to initiate and develop by stretching. Thus, the non-porous films disclosed herein can undergo a stretching process (described herein) to produce microporous films.

[0061] In one embodiment, the microporous film described herein is oriented in the machine direction. The microporous film can be oriented by cold stretching in the machine direction and thermal stretching in the machine direction after cold stretching. Alternatively or in addition, one or more cold stretches and / or one or more thermal stretches can be performed in any other direction, such as the transverse direction (across the machine direction). The cold stretch percentage can be from 25% to 150% and is determined using Equation I:

Number

Number

[0062] In some embodiments, the method of manufacturing the microporous film comprises providing the microporous film described herein, and cold stretching the film in the machine direction to a cold stretching percentage of 25% to 200% at a temperature in the range of -20 °C to 50 °C, preferably 10 °C to 50 °C. The cold stretching percentage is determined using Equation I above. After cold stretching, the film is subjected to thermal stretching in the machine direction to a thermal stretching ratio of 50% to 500% at a temperature in the range of 50 °C to 150 °C, preferably 90 °C to 140 °C or 100 °C to 140 °C. The thermal stretching percentage is determined using Equation II above.

[0063] In one embodiment, the stretching process comprises one or more cold stretching steps, followed by one or more thermal stretching steps, optionally with one or more heat curing steps. The process may optionally include a post-annealing step. Film uniformity is important, and thus it is preferred to maintain the temperature below 150 °C.

[0064] In one embodiment, the stretching process can be carried out as the film moves along a production line that may include a series of rollers. The degree of stretching in the machine direction can be controlled by using rollers with different speeds or by different diameters (diameters) of the rollers. Optionally, the degree of stretching in the transverse direction can be carried out, which can be controlled by gripping the edges of the web and stretching the film in the transverse (cross) direction between a series of clips that cross downwardly a pair of adjustable diverging rails. The polymer film at the front end of the production line may appear colorless and transparent (before stretching), but it may appear to change such that its opacity increases as it moves along the production line, such as along the region where the stretching process is carried out, a white haze develops, and then the film changes to white due to the formation of pores (and the associated light scattering effect from the void space).

[0065] Processes for stretching non-porous films to produce microporous films have been reported previously (see, for example, U.S. Patent No. 3,801,404 to Druin et al. and U.S. Patent No. 3,426,754 to Bierenbaum et al.), but these reported processes using polyethylene or polypropylene films require an annealing step, sometimes with a separate heat curing step after the stretching process (or at an intermediate point between separate film stretching stages). However, an extended annealing time is a problem from the perspective of the desired objectives for running a continuous manufacturing line for producing microporous films. Ideally, a continuous extrusion and pore formation process in one continuous manufacturing line that does not require a holding period related to extending the annealing step is preferred. Advantageously, films made from the PP copolymers (and blends thereof) described herein do not require any annealing step or heat curing step to produce a microporous film from the stretching process (in this case, the pore formation mechanism is different from that of previously reported polyethylene and polypropylene films). Thus, the PP copolymers described herein can be heated and extruded to form non-porous films that can be stretched in a continuous manufacturing line for producing microporous films.

[0066] In certain embodiments, the invention described herein comprises one or more polypropylene copolymers comprising one or more polypropylene homopolymer chain segments and one or more ethylene-containing copolymer chain segments, wherein the microporous polymer film comprises: (i) polypropylene homopolymer chain segments in an amount of 50 to 82 wt% based on the weight of the microporous polymer film or 43 to 79 mol% based on the molar content of propylene polymerization units in the polypropylene homopolymer chain segments as a percentage of the total molar content of the polymerization monomer units in the microporous polymer film; and (ii) ethylene-containing copolymer chain segments in an amount of 18 to 50 wt% based on the weight of the microporous polymer film or 21 to 57 mol% based on the molar content of the polymerization monomer units in the ethylene-containing copolymer chain segments as a percentage of the total molar content of the polymerization monomer units in the microporous polymer film, and at least a portion of the ethylene-containing copolymer chain segments comprises ethylene polymerization units in an amount of at least 45 wt% based on the weight of the ethylene-containing copolymer chain segments or at least 55 mol% based on the molar content of ethylene polymerization units in the ethylene-containing copolymer chain segments as a percentage of the total molar content of the polymerization monomer units in the ethylene-containing copolymer chain segments.

[0067] In one embodiment, a method of forming a microporous polymer film, the method steps comprising: (a) providing one or more polypropylene copolymers comprising: (i) one or more polypropylene homopolymer chain segments, based on the weight of the polypropylene copolymer, from 50 to 82 wt% or as a percentage of the total molar content of the polymerized monomer units in the polypropylene copolymer, one or more polypropylene homopolymer chain segments in a total amount of from 43 to 79 mol% based on the molar content of the polymerized propylene units in the polypropylene homopolymer chain segments; and (ii) one or more ethylene-containing copolymer chain segments, based on the weight of the polypropylene copolymer, from 18 to 50 wt% or as a percentage of the total molar content of the polymerized monomer units in the polypropylene copolymer, one or more ethylene-containing copolymer chain segments in a total amount of from 21 to 57 mol% based on the molar content of the polymerized monomer units in the ethylene-containing copolymer chain segments, wherein at least a portion of the ethylene-containing copolymer chain segments contains polymerized ethylene units in an amount of at least 55 mol% based on the molar content of the polymerized ethylene units in the ethylene-containing copolymer chain segments, based on the weight of the ethylene-containing copolymer chain segments or as a percentage of the total molar content of the polymerized monomer units in the ethylene-containing copolymer chain segments; (b) forming a non-porous film from the polypropylene copolymer; and (c) subjecting the non-porous film to a continuous cold stretching and hot stretching step comprising: (i) at least one cold stretching step at a temperature in the range of -20°C to 50°C; and (ii) at least one hot stretching step at a temperature in the range of 50°C to 150°C, thereby producing a microporous polymer film.

[0068] In some embodiments, the method is a continuous process for manufacturing a microporous polymer film. In particular, in some embodiments, the method proceeds without any annealing step after the formation of the non-porous film, and proceeds without any annealing or heat curing step after the formation of the microporous polymer film, and is a continuous process for manufacturing a microporous polymer film.

[0069] The present invention relates to a microporous film manufactured by the method described herein, and further relates to an article manufactured from the microporous film described herein.

[0070] The total thickness of the microporous film is not particularly limited and can be less than 2.54 mm (100 mils) in some embodiments. Different film thicknesses may be required depending on different end uses, or conversely, different film thicknesses may be more appropriate for some end uses. For example, a microporous film suitable for use as a house wrap can have a thickness of 51 - 254 μm (2 - 10 mils), preferably 102 - 178 μm (4 - 7 mils). A microporous film suitable for use as a roof membrane in Europe can have a thickness of 102 - 508 μm (4 - 20 mils), preferably 127 - 254 μm (5 - 10 mils), or a microporous film suitable for use as a roof membrane in North America can have a thickness of 508 - 2032 μm (20 - 80 mils), preferably 1016 - 1524 μm (40 - 60 mils). Also, a microporous film suitable for medical applications such as a packaging wrap for surgical packs can have a thickness in the range of 51 - 508 μm (2 - 20 mils), for example 127 - 254 μm (5 - 10 mils).

[0071] The thickness of the film can depend on the end use of the microporous film discussed herein, and all thicknesses and ranges of thicknesses are considered suitable for the microporous film of the present invention. Accordingly, all individual values and subranges less than 2540 μm (100 mils) are included and disclosed herein. For example, in some embodiments, the total thickness of the microporous film (in μm) can be 2540, 2032, 1524, 1270, 1016, 762, 508, 381, 254, 203, 178, 152, 127, 102, 51, 38, 25, 13, or 2.5 μm. Each of the foregoing numbers can be preceded by the words "about," "at least about," or "about to less than," and any of the foregoing numbers can be used alone or in combination to describe a non-limiting range or to describe a limiting range. In further embodiments, the total thickness of the microporous film can be 2.5 to 152.4 μm (0.1 to 6 mils), 2.5 to 102 μm (0.1 to 4 mils), 2.5 to 50.8 μm (0.1 to 2 mils). In further embodiments, the total thickness of the film can be 2.5 to 38.1 μm (0.1 to 1.5 mils).

[0072] The films described herein are microporous with specific pore sizes and porosities that can be varied to control the desirable and useful barrier properties for a selected end use. For housewrap films and roof membranes, for example, the same type of barrier properties such as water vapor transmission rate (WVTR) and permeability are important. The water vapor transmission rate depends on the film thickness. Permeability is the normalized water vapor transmission rate, assuming a constant pressure differential across the film when comparing different film samples, and records the WVTR with adjusted film thickness, and all "perm" herein is US perm. 1 US perm = 5.72×10 -8 g / Pa·s·m 2 . For building wrap applications, suitable average pore sizes (nm) can be 30 to 300 nm, and suitable film porosities to achieve a water vapor permeability of 10 to 100 perm can be 25 to 55% (and the WVTR is 70 to 700 grams / 24 h·m 2can be in the range). Also, for the roof film, a suitable median average pore size (nm) can be 30 - 250 nm, and a suitable film porosity to achieve a transmission of 10 - 70 perm can be 25 - 45% (and the WVTR is 70 - 500 grams / 24 h·m 2 can be in the range). In the medical packaging field, the same barrier properties are important, but the focus regarding permeability is usually the air (or gas sterilant) permeability measured as Gurley air permeability and the maximum intrusion in the ASTM F2638 test (regarding porous packaging as a surrogate microbial barrier) (calculated %P max ) measured by, targeting the barrier against bacteria / microorganisms. For medical packaging, a suitable average pore size (nm) can be 300 - 1,000 nm, and a useful range of Gurley air permeability of 1 - 100 seconds / 100 cm 3 and a calculated %P of less than 10 max A suitable film porosity to achieve the value can be 55 - 75% (P max is better the smaller it is).

[0073] In some embodiments, the microporous polymer film has a porosity of at least about 20%, and the maximum porosity is not particularly limited. In the same or other embodiments, the microporous polymer film has a porosity of up to about 75%, and the minimum porosity is not particularly limited. For example, the microporous polymer film can have a porosity (%) of 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80%. Each of the foregoing numbers can be preceded by the words "about", "at least about" or "about - less than", and any of the foregoing numbers can be used alone to describe a non - limiting range or in combination to describe a limiting range. For example, without limitation, the microporous polymer film can have a porosity of at least about 20%, about 20% - about 75% or about 25% - about 70%.

[0074] In some embodiments, the microporous polymer film has a median average pore size (by volume) of at least about 20 nm, and the maximum median pore size is not particularly limited. In the same or other embodiments, the microporous polymer film has a median pore size up to about 2000 nm, and the minimum median pore size is not particularly limited. For example, the microporous polymer film can have a median pore size (nm) of 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 900, 1000, 1500, 2000 nm. Each of the foregoing numbers can be preceded by the words "about", "at least about" or "less than about", and any of the foregoing numbers can be used alone or in combination to describe a non-limiting range or to describe a limiting range. For example, but not limited to, the microporous polymer film can have a median pore size of at least about 20 nm, about 20 nm to about 1000 nm or about 25 nm to about 1000 nm.

[0075] In some embodiments, the microporous polymer film has a permeance of at least about 1 perm, and the maximum permeance is not particularly limited. In the same or other embodiments, the microporous polymer film has a permeance up to about 150 perm, and the minimum permeance is not particularly limited. For example, the microporous polymer film can have a permeance (perm) of 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140 or 150 perm. Each of the foregoing numbers can be preceded by the words "about", "at least about" or "less than about", and any of the foregoing numbers can be used alone or in combination to describe a non-limiting range or to describe a limiting range. For example, but not limited to, the microporous polymer film can have a permeance of at least about 10 perm, about 10 perm to about 100 perm or about 20 perm to about 100 perm.

[0076] In some embodiments, the microporous polymer film has a microporous flow rate of at least about 1 sec / 100 cm 3 and the maximum Gurley air permeability is not particularly limited. In the same or other embodiments, the microporous polymer film has a Gurley Hill Porosity (herein referred to as "Gurley Air Permeability") of about 35,000 sec / 100 cm 3 For example, the microporous polymer film may have a Gurley air permeability of 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140 or 150, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1500, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 15000, 20000, 25000, 30000, 35000 seconds / 100 cm. 3 Gurley air permeability (sec / 100cm 3 Each of the foregoing numbers may be preceded by the words "about," "at least about," or "less than about," and any of the foregoing numbers may be used alone to describe open ranges or in combination to describe limited ranges. For example, but not limited to, a microporous polymeric film may have a viscosity of at least about 1 sec / 100 cm 3 , about 1 second / 100cm 3 ~About 10000 seconds / 100cm 3 , or about 10 seconds / 100 cm 3 ~About 5000 seconds / 100cm 3 , or about 10 seconds / 100 cm 3 ~About 1000 seconds / 100cm 3 , or about 10 seconds / 100 cm 3 ~About 100 seconds / 100cm 3 The woven fabric may have a Gurley air permeability of 100%.

[0077] In some embodiments, the microporous polymer film has a % Maximum Penetration (%P) calculated by ASTM F2638-18 test of less than about 10. max ) and has a barrier against microorganisms, as measured bymax is not particularly limited. For example, the microporous polymer film has a calculated %P max less than 10, 5, 2, 1, 0.5, 0.2, 0.1, 0.05, 0.03, 0.02, 0.015, 0.010, 0.005. Each of the foregoing numbers can be preceded by the words "about", "at least about" or "less than about", and any of the foregoing numbers can be used alone or in combination to describe a non-limiting range or to describe a limiting range. For example, but not limited to, the microporous polymer film has a calculated %P max less than about 10, about 0 to about 10 or about 0 to about 1. max Ideally, the calculated %P max value is zero, but the limit for detection cannot be zero. The calculated %P

[0078] The films described herein do not use the addition of fillers such as calcium carbonate, CaCO3, etc. to produce high water vapor permeability water vapor permeable films. Accordingly, the films described herein contain less than 5% by weight of filler based on the total weight of the polymer present in the film. Exemplary fillers can include, but are not limited to, CaCO3, clay, silica, alumina, titania, zirconia, ceria, talc, magnesium carbonate, calcium sulfate, barium sulfate, porous glass beads, porous polymer beads, ceramic beads, aluminum trihydroxide, magnesium trihydroxide, wollastonite whiskers, wood flour, lignin, starch, clay, carbon black, graphite, graphene, carbon nanotubes, carbon fibers, carbon nanofibers or combinations thereof. In further embodiments, the films described herein contain less than 3% by weight, less than 2% by weight, less than 1% by weight or less than 0.5% by weight of filler based on the total weight of the polymer present in the film. In some embodiments, the films described herein do not contain filler (0% by weight). In many pharmaceutical applications, 0% by weight of filler is preferred to minimize the potential for particulate contamination of such films and particle breakage of the film.

[0079] The films described in this specification may incorporate UV stabilizers if the specifically intended use may include outdoor applications. Representative UV stabilizer additives include ultraviolet light absorbers such as Tinuvin® 329 (BASF, Ludwigshafen, Germany) and hindered amine light stabilizers such as Tinuvin® 770 or Chimassorb® 2020 (both BASF). For example, an effective UV stabilizer package for the microporous film of polypropylene copolymer PP C7054-07NA may include a combination of 0.75 wt% Chimassorb® 2020, 0.25 wt% Tinuvin® 770, 0.25 wt% Tinuvin® 329, and 0.15 wt% Irganox® B215 (antioxidant, BASF). The PP C7054-07NA microporous film without UV additives changed to powder after an 8-week UV aging test at 50°C. In contrast, the PP C7054-07NA microporous film with the above UV additive package showed no visual defects such as cracks, yellowing, or deformation after an 8-week UV aging test at 50°C.

[0080] The films described herein may incorporate other additives such as antioxidants (e.g., hindered phenolic resins such as IRGANOX® 1010 or IRGANOX® 1076 (supplied by Ciba Geigy)), phosphates (e.g., IRGAFOS® 168 (supplied by Ciba Geigy)), processing aids, UV light stabilizers, heat stabilizers, pigments, colorants, antistatic additives, flame retardants, slip agents, antiblocking additives, biocides, antibiotic agents, and clarifying / nucleating agents (e.g., HYPERFORM® HPN-20E, MILLAD® 3988, MILLAD® NX 8000 (available from Milliken Chemical)). Other additives may be included in the film at concentrations typically used in the art to achieve their desired purpose. In some examples, one or more additives are included in an amount ranging from 0 to 10 wt% based on the total polymer weight of the film or from 0 to 5 wt%, 0.001 to 5 wt%, 0.001 to 3 wt%, 0.05 to 3 wt%, or 0.05 to 2 wt% based on the total polymer weight of the film. In embodiments of the present specification where the filler has other uses such as a colorant or pigment, they are present in a total amount of less than 5 wt%.

[0081] The present specification also describes laminates. A laminate includes the microporous film described above in the present specification and a nonwoven substrate that is at least partially adhered to the film. As used herein, "nonwoven substrate" includes nonwoven webs, nonwoven fabrics, and any nonwoven structure in which fibers or yarns are incorporated other than in a regular or repeating pattern. The nonwoven substrates described herein can be formed by various processes such as, for example, airlaid processes, meltblown processes, spunbond processes, and carding processes including bonded carded web processes. Nonwoven webs can include single webs such as spunbond webs, carded webs, airlaid webs, spunlaced webs, or meltblown webs. However, due to the relative strengths and weaknesses associated with the various processes and materials used to manufacture nonwoven fabrics, a composite structure of two or more layers can be used to achieve a better balance of properties. Such structures are often identified by letters indicating the various layers, for example, SM for a two-layer structure consisting of a spunbond layer and a meltblown layer, SMS for a three-layer structure, or more generally SXnS where S is a spunbond layer and X can independently be a spunbond layer, a carded layer, an airlaid layer, a spunlaced layer, or a meltblown layer, and n can be any number but is practically generally less than 5. In order to maintain the structural integrity of such composite structures, the layers must be joined together. Common joining methods include thermal calendar point bonding, adhesive lamination, ultrasonic bonding, and other methods known to those skilled in the art. All of these structures can be used in the present invention, particularly when incorporated with the microporous film in the form of a laminate.

[0082] The microporous films described herein should find use in housing and construction, for example, as a barrier layer for building envelopes such as housewraps and roofing membranes.

[0083] This specification also describes articles. The articles include the films or laminates described above in this specification. In some embodiments, the breathable backsheet includes the microporous film described herein. In other embodiments, the breathable backsheet includes a laminate. The articles can be used in a variety of hygiene and medical applications. In some embodiments, the articles can include diapers, training pants, and adult incontinence articles or other similar absorbent clothing articles. In other embodiments, the articles can include air masks, medical drapes, gowns, surgical gowns, and protective clothing or other fabric (woven or non-woven) articles.

[0084] This embodiment is applicable to other technologies that are susceptible to the influence of similar problems as described above. For example, the film can be used to manufacture cloth-like backsheets and medical backtable (or end table) covers in operating rooms, as well as medical packaging (e.g., medical sterilization pouches and sterilization pouches for containing sterilized surgical devices) and active packaging (e.g., sachets for containing desiccants in pharmaceutical tablet bottles). All of these are within the scope of this embodiment. The interstitial space between the pores of the microporous polymer film described in this specification contains thin solid segments of PP homopolymer or PP homopolymer and E / P copolymer, different from other candidates for breathable fiber products, which may or may not contain fibers that are (typically by thermal bonding at the contact points they encounter) bonded. The advantage of the microporous polymer film of the present invention is that the stretching process of the present invention enables better control of the pore size and pore size distribution. As a result, pores are formed by overlapping fibers, and the pore size and distribution are the number density (fibers / cm 3a pore size distribution that is narrower than that of other (fibrous) porous structures that depend on the number) and the distribution of fiber diameters. Furthermore, the microporous polymer film of the present invention has smaller pores with diameters in the nanometer range compared to fibrous-like materials having very much larger pore diameters in the range of several micrometers. A fibrous structure can be produced from a similar hydrophobic material, but the smaller pore diameter of the PP-copolymer microporous polymer film can provide a higher resistance to blood and body fluids, thereby making it possible to use them as a breathable cover for an operating room end table. Another advantage of the microporous polymer film described herein compared to fibrous-like breathable films is that the possibility of fragments resulting from the handling, cutting, conversion, and use of the microporous polymer film is much less than in the case of fibrous structures. Thereby, the microporous polymer film is suitable for use in ultra-clean spaces in electronic processing, filtration, and sterile environments in medicine and pharmaceuticals.

[0085] The microporous film can also find use in regular packaging (such as casings, fruit packaging, powder packaging, packaging for sensitive electronic components, etc.) and as a filtration medium (for the separation of gases or liquids). The film can be a single-layer film or a multilayer film. As used herein, "multilayer film" refers to a film having two or more layers that are at least partially adjacent and preferably, but optionally, have the same extent.

[0086] A PP copolymer film further comprising an ethylene-propylene elastomer Furthermore, a microporous film containing a PP copolymer and ethylene-containing copolymer chain segments in a total amount of 18 to 50% by weight and having a lower tensile modulus is considered particularly desirable for some applications. The tensile modulus of the film is related to the flexibility of the film; furthermore, a film with a low tensile modulus has the potential for improved toughness, installation by hot air welding, and low-temperature durability.

[0087] However, it has been found that even when the PP copolymer has ethylene-containing copolymer chain segments, the polypropylene breathable film can still be relatively rigid. Furthermore, it has been found that the addition of ethylene-propylene rubber can further modify the microporous film and reduce its tensile modulus.

[0088] Accordingly, in some embodiments, the present invention relates to a microporous polymer film, which is: (a) one or more polypropylene copolymers in an amount of 50 to 95 weight percent based on the total weight of the film, the polypropylene copolymer comprising one or more polypropylene homopolymer chain segments and one or more ethylene-containing copolymer chain segments; the microporous polymer film (i) polypropylene homopolymer chain segments, based on the weight of the polypropylene copolymer, in an amount of 50 to 82 weight percent or, as a percentage of the total molar content of the polymerized monomer units in the polypropylene copolymer, a total amount of polypropylene homopolymer chain segments in an amount of 43 to 79 mol% based on the molar content of the polymerized propylene units in the polypropylene homopolymer chain segments, and (ii) ethylene-containing copolymer chain segments, based on the weight of the polypropylene copolymer, in an amount of 18 to 50 weight percent or, as a percentage of the total molar content of the polymerized monomer units in the polypropylene copolymer, a total amount of ethylene-containing copolymer chain segments in an amount of 21 to 57 mol% based on the molar content of the polymerized monomer units in the ethylene-containing copolymer chain segments, comprising one or more polypropylene copolymers, wherein at least a portion of the ethylene-containing copolymer chain segments comprises polymerized ethylene units in an amount of at least 55 mol% based on the molar content of the polymerized ethylene units in the ethylene-containing copolymer chain segments, based on the weight of the ethylene-containing copolymer chain segments, in an amount of at least 45 weight percent or, as a percentage of the total molar content of the polymerized monomer units in the ethylene-containing copolymer chain segments, (b) 5 to 50 weight percent, based on the total weight of the film, of one or more ethylene-propylene elastomers; and (b) at least 45 weight percent of the polymerized units in the ethylene-propylene elastomer are units of ethylene.

[0089] All of the details, options, variations, manufacturing details and processes, and uses described hereinabove in this specification for the invention described for the combination of (i) and (ii) containing only (a) or including (a), i.e., excluding (b), are intended to be equally applicable or suitable to all inventions containing or consisting of (a) and (b), unless specifically stated otherwise herein.

[0090] In some preferred embodiments, (b) the ethylene-propylene elastomer has an ethylene content very similar or identical to the ethylene content in the ethylene-containing copolymer chain segments in the polypropylene copolymer. By doing so, the further incorporation of ethylene-propylene rubber into the PP breathable film does not affect the pore-forming ability of the PP copolymer. As a result, the ethylene-propylene rubber is considered to offer the possibility of a PP breathable film having further properties such as improved toughness. Other potentially improved properties include better flexibility at lower temperatures, such as may be experienced in the installation of such films in roofing applications during the winter in extremely cold weather. Along with the possibility of increased porosity and breathability of the PP breathable film, other property improvements such as improved heat welding and / or improved tear strength are also considered possible.

[0091] In some embodiments, one or more ethylene-propylene elastomers (b) are present in the film in an amount of 5 to 30 weight percent, based on the total of (a) one or more polypropylene copolymers and (b) one or more ethylene-propylene elastomers in the film. In some other embodiments, one or more ethylene-propylene elastomers (b) are present in the film in an amount of 5 to 20 weight percent, based on the total of (a) one or more polypropylene copolymers and (b) one or more ethylene-propylene elastomers in the film.

[0092] In one or more ethylene-propylene elastomers (b), at least 45 weight percent of the polymerized units are units of ethylene. In some embodiments, 45 to 80 weight percent of the polymerized units in the (b) ethylene-propylene elastomer are units of ethylene. In some other embodiments, 45 to 60 weight percent of the polymerized units in the (b) ethylene-propylene elastomer are units of ethylene.

[0093] Ethylene-propylene elastomer means any elastomer or rubber having an ethylene-propylene segment. An elastomer is a polymer having viscoelasticity (i.e., both viscosity and elasticity), and generally has weak intermolecular forces with a generally low Young's modulus and high fracture strain as demonstrated by polymers having extensibility and elasticity, compared to other materials.

[0094] Preferably, (b) one or more ethylene-propylene elastomers are a single type of ethylene-propylene elastomer. When (b) one or more ethylene-propylene elastomers are a mixture of ethylene-propylene elastomers, preferably all of these elastomers each have the above-described amount of polymerized ethylene units; that is, in the (b) ethylene-propylene elastomer, all elastomers have at least 45 weight percent of polymerized units that are units of ethylene; or in some embodiments, all have 45 to 80 weight percent of the polymerized units of the (b) ethylene-propylene elastomer that are units of ethylene; or in some other embodiments, 45 to 60 weight percent of the polymerized units in the (b) ethylene-propylene elastomer are units of ethylene.

[0095] In many embodiments, (b) one or more ethylene-propylene elastomers preferably include ethylene-propylene rubber; however, in some embodiments, ethylene propylene diene monomer (EPDM) rubber may be desirable. Mixtures of these rubbers are also possible. Preferably, (b) one or more ethylene-propylene elastomers are only ethylene propylene-rubber or only ethylene propylene diene monomer (EPDM) rubber. Other suitable ethylene propylene elastomers include Vistalon™ from ExxonMobil Chemical Company, Buna® from Lanxess, and Mitsui EPT™ from Mitsui Chemicals. Any ethylene-propylene elastomer having the above-described amount of polymerized ethylene units would be suitable in (b).

[0096] (b) One or more ethylene-propylene elastomers preferably have a Mooney viscosity of 10 to 40 Mu as measured by ASTM D1646-07. When using a mixture of elastomers, each elastomer has a Mooney viscosity of 10 to 40 Mu as measured under ASTM D1646-07.

[0097] The microporous polymer film includes (a) and (b) as described above. In some embodiments, the microporous polymer film consists of (a) and (b) as described above. In some embodiments, the microporous polymer film including or consisting of (a) and (b) has a tensile modulus smaller than that of the film made of (a) only. In some other embodiments, the microporous polymer film including or consisting of (a) and (b) has a water vapor permeability lower than that of the film made of (a) only.

[0098] In the microporous film, in (a) one or more polypropylene copolymers, at least a part of the ethylene-containing copolymer chain segment contains ethylene polymerization units in an amount of 45% to 80% by weight based on the weight of the ethylene-containing copolymer chain segment, or in an amount of 55 mol% to 86 mol% based on the molar content of the ethylene polymerization units in the ethylene-containing copolymer chain segment, as a percentage of the total molar content of the polymerization monomer units in the ethylene-containing copolymer chain segment.

[0099] In some embodiments of the microporous polymer film including or consisting of (a) and (b), the ethylene-containing copolymer chain segment in (a) one or more polypropylene copolymers is an ethylene-propylene copolymer chain segment.

[0100] In some embodiments of the microporous polymer film comprising or consisting of (a) and (b), (a) the ethylene-containing copolymer chain segments in one or more polypropylene copolymers comprise ethylene-propylene copolymer chain segments, and at least a portion of the ethylene-propylene copolymer chain segments in (a) contains polymerization units of ethylene in an amount of 45 wt% to 80 wt% based on the weight of the ethylene-propylene copolymer chain segment, or 55 mol% to 86 mol% based on the molar content of the polymerization units of ethylene in the ethylene-propylene copolymer chain segment, as a percentage of the total molar content of the polymerization monomer units in the ethylene-propylene copolymer chain segment.

[0101] In some further embodiments, (a) these ethylene-propylene copolymer chain segments in one or more polypropylene copolymers are ethylene-propylene diblock copolymer chain segments comprising a polypropylene block and a polyethylene block, or diblock copolymer chain segments comprising a polypropylene block and an ethylene-propylene copolymer block.

[0102] In some embodiments, the microporous polymer film comprising or consisting of (a) and (b) has a porosity of at least 25% and a median pore diameter of at least 25 nm (4V / A, by UOP method 578-11), both of which are measured by mercury intrusion porosimetry.

[0103] In some embodiments, the microporous polymer film comprising or consisting of (a) and (b) is a non-porous polymer film having domains of (a) and domains of (b), and the domains of (a) further have a morphology characterized by a plurality of polymer phases of polypropylene, a plurality of minority polymer domains of the ethylene-containing copolymer within the plurality of polymer phases, and inclusion phases of the major polypropylene phase within the minority polymer domains.

[0104] It has been found that the microporous polymer film comprising or consisting of (a) and (b) has multiple uses. In many applications, a non-porous microporous polymer film having a thickness of at least 100 μm to 2.5 mm is particularly suitable.

[0105] For example, the microporous polymer film comprising or consisting of (a) and (b) is suitable for use as a roof membrane or a component of a roof membrane. The low permeability of current roof membranes made of PVC, TPO or EPDM leads to water accumulation under the roof membrane (e.g., on a metal roof and / or a lightweight concrete structure), resulting in delamination of the roof membrane from the roof over time and then damage to the roof structure. The microporous polymer film comprising or consisting of (a) and (b) provides an opportunity to provide a liquid-tight product with high water vapor permeability.

[0106] The microporous film comprising or consisting of (a) and (b) is also suitable for use in medical packaging or active packaging articles, or medical covers such as back table covers. When used in medical packaging or active packaging articles, or medical back table covers, the microporous polymer film comprising or consisting of (a) and (b) preferably has a barrier against microorganisms corresponding to a calculated maximum penetration %Pmax of less than 10% as defined by ASTM F2638-18. Similarly, when used in medical packaging or active packaging articles, or medical back table covers, the microporous polymer film comprising or consisting of (a) and (b) preferably has a Gurley air permeability of 1 to 35,000 seconds / 100 cm 3 which controls the inflow or outflow of air or one or more gases into and out of the package. The microporous polymer film comprising or consisting of (a) and (b) is thermoformable and heat sealable and is particularly useful in medical packaging or active packaging articles, or medical back table covers, and many other different applications.

[0107] Method for forming a PP copolymer film further comprising an ethylene-propylene elastomer In yet another alternative embodiment, the present invention further relates to a method for forming a microporous polymer film, the method steps comprising: A) providing a mixture, the mixture comprising: (a) one or more polypropylene copolymers in an amount of 50 to 95 weight percent based on the total weight of the mixture, wherein: (i) one or more polypropylene homopolymer chain segments in an amount of 50 to 82 weight percent based on the weight of the polypropylene copolymer or in an amount of 43 to 79 mole percent based on the molar content of propylene polymerization units in the polypropylene homopolymer chain segments as a percentage of the total molar content of polymerization monomer units in the polypropylene copolymer, and (ii) one or more ethylene-containing copolymer chain segments in an amount of 18 to 50 weight percent based on the weight of the polypropylene copolymer or in an amount of 21 to 57 mole percent based on the molar content of polymerization monomer units in the ethylene-containing copolymer chain segments as a percentage of the total molar content of polymerization monomer units in the polypropylene copolymer, and at least a portion of the ethylene-containing copolymer chain segments contains ethylene polymerization units in an amount of at least 45 weight percent based on the weight of the ethylene-containing copolymer chain segments or in an amount of at least 55 mole percent based on the molar content of ethylene polymerization units in the ethylene-containing copolymer chain segments as a percentage of the total molar content of polymerization monomer units in the ethylene-containing copolymer chain segments, one or more polypropylene copolymers; and (b) one or more ethylene-propylene elastomers in an amount of 5 to 50 weight percent based on the total weight of the mixture, wherein at least 45 weight percent of the polymerization units in the ethylene-propylene elastomer are ethylene units, providing the mixture; (b) one or more ethylene-propylene elastomers in an amount of 5 to 50 weight percent based on the total weight of the mixture, and providing a mixture wherein at least 45 weight percent of the polymerization units in the ethylene-propylene elastomer are ethylene units; B) forming a non-porous film from the mixture; and C) subjecting the non-porous film to (i) at least one cold drawing step at a temperature in the range of -20°C to 50°C, and (ii) at least one hot drawing step at a temperature in the range of 50°C to 140°C subjected to a continuous cold drawing and hot drawing step including thereby producing a microporous polymer film.

[0108] All of the details, options, variations, manufacturing details and processes, and uses, including the equipment, described hereinabove for the invention described for the combination of (i) and (ii) containing only (a) or including (a), i.e., excluding (b), are intended to be equally applicable or suitable to all inventions containing or consisting of (a) and (b), unless specifically stated otherwise herein. Specifically, all of the details and equipment regarding the longitudinal and transverse drawing of the film described hereinabove are suitable for treating films containing or consisting of (a) and (b), unless other specific differences are shown. Providing a mixture containing or consisting of (a) and (b) can be achieved, without limitation, by compounding the components with a screw extruder, preferably a twin-screw extruder. The formation of a non-porous film can be achieved, without limitation, by casting the film directly from the extruder after mixing. Subjecting the cast film to cold and hot drawing steps can be achieved by the methods discussed and exemplified herein.

[0109] In some preferred embodiments of forming the microporous polymer film, (b) the ethylene-propylene elastomer has an ethylene content that is very similar or identical to the ethylene content in the ethylene-containing copolymer chain segments in the polypropylene copolymer. By doing so, the further incorporation of the ethylene-propylene rubber into the PP breathable film does not affect the pore-forming ability of the PP copolymer. As a result, the ethylene-propylene rubber is considered to provide the possibility of a PP breathable film having further properties such as improved toughness. Other potentially improved properties include better flexibility at lower temperatures, as may be experienced in the installation of such films in roofing applications during the winter in extremely cold weather. Along with the possibility of increased porosity and breathability of the PP breathable film, other property improvements such as improved heat welding and / or improved tear strength are also considered possible.

[0110] In some embodiments of the method of forming a microporous polymer film, (b) one or more ethylene-propylene elastomers are present in the mixture in an amount of 5 to 30 weight percent, based on the total weight of (a) one or more polypropylene copolymers and (b) one or more ethylene-propylene elastomers in the mixture. In some other embodiments, (b) one or more ethylene-propylene elastomers are present in the mixture in an amount of 5 to 20 weight percent, based on the total weight of (a) one or more polypropylene copolymers and (b) one or more ethylene-propylene elastomers in the mixture. In (b) one or more ethylene-propylene elastomers, at least 45 weight percent of the polymerized units are units of ethylene. In some embodiments, 45 to 80 weight percent of the polymerized units in (b) the ethylene-propylene elastomer are units of ethylene. In some other embodiments, 45 to 60 weight percent of the polymerized units in (b) the ethylene-propylene elastomer are units of ethylene. Preferably, (b) one or more ethylene-propylene elastomers are a single type of ethylene-propylene elastomer. When (b) one or more ethylene-propylene elastomers are a mixture of ethylene-propylene elastomers, preferably, all of these elastomers each have the above-described amount of polymerized ethylene units; that is, in (b) the ethylene-propylene elastomer, all elastomers have at least 45 weight percent of the polymerized units that are units of ethylene; or in some embodiments, all have 45 to 80 weight percent of the polymerized units of (b) the ethylene-propylene elastomer that are units of ethylene; or in some other embodiments, 45 to 60 weight percent of the polymerized units in (b) the ethylene-propylene elastomer are units of ethylene.

[0111] In some embodiments of forming a microporous polymer film, (b) the one or more ethylene-propylene elastomers preferably include ethylene-propylene rubber; however, in some embodiments, ethylene propylene diene monomer (EPDM) rubber may be desirable. Mixtures of these rubbers are also possible. Preferably, (b) the one or more ethylene-propylene elastomers are only ethylene propylene rubber or only ethylene propylene diene monomer (EPDM) rubber. Other suitable ethylene propylene elastomers include Vistalon (trademark) of ExxonMobil Chemical Company, Buna (registered trademark) of Lanxess, and Mitsui EPT (trademark) of Mitsui Chemicals. Any ethylene-propylene elastomer having the aforementioned amount of polymerized ethylene units would be suitable for (b).

[0112] In some embodiments of the method of forming a microporous polymer film, (b) the one or more ethylene-propylene elastomers preferably have a Mooney viscosity of 10 to 40 Mu as measured by ASTM D1646-07. When using a mixture of elastomers, each elastomer has a Mooney viscosity of 10 to 40 Mu as measured under ASTM D1646-07.

[0113] In some embodiments of the method for forming a microporous polymer film, the mixture used to produce the microporous polymer film comprises (a) and (b) as described above. In some embodiments of the method for forming a microporous polymer film, the mixture used to produce the microporous polymer film consists of (a) and (b) as described above. In some embodiments of the method for forming a microporous polymer film, the microporous polymer film made from a mixture comprising or consisting of (a) and (b) has a tensile modulus smaller than that of a film made of (a) alone. In some embodiments of the method for forming a microporous polymer film, the microporous polymer film made from a mixture comprising or consisting of (a) and (b) has a water vapor permeability smaller than that of a film made of (a) alone.

[0114] In some embodiments of the method for forming a microporous polymer film, in (a) one or more polypropylene copolymers, at least a portion of the ethylene-containing copolymer chain segments contain ethylene polymerization units in an amount of 45 wt% to 80 wt% based on the weight of the ethylene-containing copolymer chain segments, or in an amount of 55 mol% to 86 mol% based on the molar content of the ethylene polymerization units in the ethylene-containing copolymer chain segments, as a percentage of the total molar content of the polymerization monomer units in the ethylene-containing copolymer chain segments.

[0115] In some embodiments of the method for forming a microporous polymer film made from a mixture comprising or consisting of (a) and (b), the ethylene-containing copolymer chain segments in (a) one or more polypropylene copolymers are ethylene-propylene copolymer chain segments.

[0116] In some embodiments of a method of forming a microporous polymer film made from a mixture comprising or consisting of (a) and (b), the ethylene-containing copolymer chain segments in one or more polypropylene copolymers of (a) comprise ethylene-propylene copolymer chain segments, and at least a portion of the ethylene-propylene copolymer chain segments in (a) contain polymerization units of ethylene in an amount of 45 wt% to 80 wt% based on the weight of the ethylene-propylene copolymer chain segment as a percentage of the total molar content of the polymerization monomer units in the ethylene-propylene copolymer chain segment, or contain 55 mol% to 86 mol% based on the molar content of the polymerization units of ethylene in the ethylene-propylene copolymer chain segment.

[0117] In some further embodiments, these ethylene-propylene copolymer chain segments in one or more polypropylene copolymers of (a) are ethylene-propylene diblock copolymer chain segments comprising polypropylene blocks and polyethylene blocks, or diblock copolymer chain segments comprising polypropylene blocks and ethylene-propylene copolymer blocks.

[0118] In some embodiments of a method of forming a microporous polymer film made from a mixture comprising or consisting of (a) and (b), the resulting film has a porosity of at least 25% and a median pore diameter of at least 25 nm (4V / A, by UOP method 578-11), both characteristics being measured by mercury intrusion porosimetry.

[0119] In some embodiments of a method of forming a microporous polymer film made from a mixture comprising or consisting of (a) and (b), the film is a non-porous polymer film having domains of (a) and domains of (b), and the domains of (a) further have a morphology characterized by a plurality of polymer phases of polypropylene, a plurality of minority polymer domains of the ethylene-containing copolymer within the plurality of polymer phases, and inclusion phases of the major polypropylene phase within the minority polymer domains.

[0120] The present invention will be further clarified in the following examples, where all parts and percentages are by weight unless otherwise specified. While these examples illustrate preferred embodiments of the present invention, it should be understood that they are presented by way of example only and should in no way be construed as limiting. From the foregoing discussion and these examples, those skilled in the art will be able to identify the essential features of the present invention and make various changes and modifications to the present invention to adapt it to various applications and conditions without departing from its spirit and scope.

Examples

[0121] Materials The homopolymer polyethylene is referred to herein as PE. The homopolymer-PE used herein is the resin HDPE 6400, available from Dow Chemical Company, Midland, MI, USA.

[0122] The homopolymer polypropylene is referred to herein as PP. The homopolymer-PP used herein is the resin PP H314, available from Braskem, USA (Philadelphia, PA, USA).

[0123] The ethylene-propylene copolymer is referred to herein as EP. A number of EP and PP-EP copolymers and blends of homopolymer-PP with EP or PP-EP copolymers are described herein, for example, as detailed in Examples 2 and 6.

[0124] The polypropylene copolymer resin used in this study was PP C7054-07NA purchased from Braskem USA, i.e., a PP-EP copolymer containing PP chain segments and ethylene-propylene random copolymer chain segments. The PP C7054-07NA resin contains 32.9 wt% ethylene-propylene copolymer (and 100 - 32.9 = 67.1% PP), and the ethylene content in the ethylene-propylene copolymer chain segments is 49.7 wt%. It has a density of 0.9 g / cm 3 and a melt index of 7 g / 10 min at 230 °C and 2.16 kg. Other PP copolymer resins are listed in Table 2.

[0125] The term "Tyvek®" by itself means Tyvek® housewrap (about 32% porosity; average pore diameter of 37 nm), and the term "Tyvek® 1073B" means a special grade of Tyvek® nonwoven fabric used as a medical packaging layer (about 65% porosity; average pore diameter of 2500 nm).

[0126] Cast film The PP C7054-07NA resin cast film was produced on a film casting line consisting of a 1.25-inch Killion single-screw extruder and a 30-inch-wide cast die with a die gap of about 762 μm (30 mils). A typical temperature profile (for extruder zones 1 - 8) of a pilot-scale extrusion line using a 76.2 cm (30-inch) die used to produce the (co)polymer cast films described herein could be as follows (e.g., for a PP copolymer film): 180, 200, 210, 210, 210, 210, 210, 210 °C.

[0127] Uniaxial and biaxial stretching of the film on a Iwamoto biaxial stretcher Uniaxial stretching (machine direction orientation, MDO) procedure: The film was cut into predetermined dimensions. Adhesive tapes were attached to both ends of the film (in the transverse direction) and it was fitted to a specially designed sample holder. The sample holder plates were fixed together with five bolts. Then, the legs of the sample holder were attached onto the back of the grips of a two-axis stretcher (BIX-703, manufactured by Iwamoto Seisakusho) made by Iwamoto. Uniaxial cold stretching was performed on the film in the machine direction. Subsequently, the door of the sample chamber was closed, the sample chamber was heated up to 100 °C and then held at this temperature for 1 minute. Then, uniaxial hot stretching was performed on the film in the machine direction. The degree of cold stretching is defined by

Number

Number

[0128] After stretching, the film changed to white for the formation of a microporous structure.

[0129] Regarding biaxial stretching, a PP-based film was cut into predetermined dimensions (70 mm × 70 mm) and then loaded onto the grips of a two-axis stretcher made by Iwamoto. Biaxial simultaneous stretching was performed on the film in both directions at room temperature and then heated up to 100 °C. After holding at 100 °C for 1 minute, biaxial simultaneous stretching was performed on the film in both directions at high temperature. The degree of stretching for biaxial stretching is defined in the same way as that for uniaxial stretching.

[0130] Differential scanning calorimetry (DSC) The weight of a portion of the sample was measured and placed into an aluminum hermetic DSC pan (pan P / N 900793.901 and lid 900794.901) and sealed. The sample weight was approximately 1 - 4 mg for each sample. The samples were scanned in a TA Instruments Q2000 DSC (Differential Scanning Calorimeter) (P / N 970001.901) (s / N 2000.0877) equipped with an autosampler, a nitrogen purge of 50 ml / min, and a mechanical cooling accessory. The run parameters for the heat - cool - heat cycle were from - 20 °C to 200 °C at 10 °C / min with a sampling interval of 0.1 s / pt. The scans were analyzed using Universal Analysis V4.7A TA Instruments software. The melting points obtained from the DSC scans were presented as the output of the instrument software and corresponded to the peak temperature in the heat flow versus temperature plot for the second heating cycle.

[0131] Mercury intrusion porosimetry Mercury intrusion porosimetry analysis was performed on a Micromeritics Autopore IV 9520 in accordance with ASTM D4404 - 10. Prior to mercury analysis, the samples were mechanically degassed under vacuum at room temperature to remove any physically adsorbed species (i.e., moisture) from the sample surface.

[0132] The test conditions were Hg fill pressure 0.50 psia, Hg contact angle 130°, Hg surface tension 485 dyn / cm, Hg density 13.53 g / mL, evacuation time of 30 minutes, 5 cm 3Small-bore hardness tester with valve (solid type: 0.392 stem volume), 30-second equilibration time, 92-point pressure table (75 indentation plus 17 extrusion pressure points) and mechanical evacuation <50 μm Hg included. Collected low-high pressure intersections at about 46 psia (3.8 μm). The pressure table used was created to allow for an incremental distribution of pressure on a log scale from 0.5 to 60,000 psia and is used to detect pore diameter (aperture diameter) from 0.003 to 400 μm in diameter. As pressure is increased stepwise from vacuum to almost 60,000 psia maximum, mercury is pushed into smaller pores. By the UOP method 578-11, the average pore diameter (4V / A) is calculated based on the assumption that all pores are right circular cylinders having length (l) and diameter (d). When the total pore volume (V = πd 2 l / 4) is divided by the total pore area (= πdl), the average pore diameter (d) is 4V / A.

[0133] To confirm that the equipment was functioning properly, a silica-alumina reference material, Lot A-501-46 was analyzed. The reported (volume-based) median pore diameter of the reference sample was 0.0072 ± 0.0005 μm. Autopore reported a (volume-based) median pore diameter of 0.0072 μm.

[0134] Scanning electron microscopy (SEM) Samples were cryo-sectioned, attached to SEM stubs by carbon tape, and then coated with 30 nm of gold to mitigate charging. Using the FEI Nova NanoSEM model 600 in the secondary electron (TLD) imaging mode, the upper surface and the sectioned surface of each sample were imaged at specific locations and at various magnifications in the range of 5000x to 10,000x. To prevent beam damage to the samples, the acceleration voltage was set within 3 to 5 kV at a spot size of 3 to 4 (scale of the spot size knob) at an operating distance of about 5 mm (distance from the final pole piece of the lens to the sample when the image is in focus).

[0135] Transmission electron microscopy (TEM) The PP copolymer film was cut into small trapezoids so that the parts could be collected. On a Leica EM UC7 microtome, using a diamond knife, parts with a thickness of about 100 nanometers were collected at ambient temperature and placed on a 400-mesh virgin TEM grid for observation. The microtomed film was stained by the gas phase of a 0.5 M (mol / L) osmium tetroxide aqueous solution at ambient temperature for 3 - 5 minutes. TEM images were collected on a FEI Tecnai 12 operated at an acceleration voltage of 120 kV using a Gatan MultiScan CCD camera.

[0136] X-ray diffraction technique Small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) studies were performed at the Advanced Photon Source (Argonne National Laboratory) using the DND-CAT (5-ID-D beamline). As the X-ray source, a standard APS Undulator A was used with an X-ray energy setting of 17 keV (λ = 0.7923 Å). All samples were carried out in the normal beam transmission mode. Detector calibration was performed using silver behenate and lanthanum hexaboride standard reference materials. The two-dimensional scattering pattern was reduced to a one-dimensional dataset of scattering intensity versus scattering vector by radial integration of the two-dimensional image. Reduction and analysis of the one-dimensional pattern were performed using the commercially available software package JADE.

[0137] Water vapor transmission rate (WVTR) measurement (ASTM F1249) For evaluating the WVTR in this study, a Mocon 3 / 33 model MG module was used. The test conditions were 37.8 °C / 100% RH according to ASTM method F1249. 20.3 cm 2To concentrate the test area down to approximately 2 inches in diameter, film samples were prepared using a 76.2 μm (3 mil) aluminum foil / acrylic adhesive mask. The test cell was divided into two half sections by the film sample. To prevent outside air from leaking into the cell, the ends of the test cell were securely sealed. This was accomplished using silicone grease to assist in sealing the film to the cell (carrier gas side), and a rubber O-ring was used to seal the outer cell cover or water vapor side. The standard sample area was 50 cm 2 . During a typical test, water vapor (the test gas) continuously entered the outer half of the test cell. This gas could be generated by the instrument at 100% relative humidity (wet sponge) or at 30 - 90% relative humidity. The water vapor permeated through the film sample and then rode on the carrier gas (dry nitrogen) to the IR sensor, where a current proportional to the amount of water vapor passing through the film was generated. Data from the IR sensor was collected by a computer, and a final value explaining the water vapor transmission rate of the test material was calculated. WVTR data was reported in units of g / 24h·m 2 . The normalized WVTR, taking into account the film thickness, was reported as g·cm / 24h·m 2 .

[0138] Water Vapor Transmission Rate (ASTM E96 / E96M-16) The water vapor transmission rate was determined in accordance with ASTM E96 / E96M-16, Standard Test Methods for Water Vapor Transmission of Materials, Desiccant Method. The test specimens were cut into circular disks having a diameter of 90.3 mm. The pockets of the dishes were filled with calcium chloride up to within 6.4 mm (1 / 4 inch) of the test specimens. The test specimens were then fitted onto the dishes just above the pockets with 76.1 mm of the diameter of the test specimens, where the metal plates were exposed to the environment. The test specimens were prepared with the outer surface of the product facing the desiccant. The assembly was then placed in a control chamber operating at a temperature and relative humidity (RH) of 23 ± 2 °C and 50 ± 5% RH, respectively. The weight of the assembly was then measured periodically. The water vapor transmission rate data was reported in units of "perm" and it was possible to convert the permeation to water vapor transmission in units of g / 24h·m2. In this specification, any use of the unit "perm" means US perm. 1 US perm = 5.72×10 -8 g / (Pa·s·m 2 )。

[0139] Gurley Hill Porosity (Gurley Air Permeability) To measure the Gurley flow value of the microporous film, a Genuine Gurley Instruments Densometer and a Lorentzen & Wettre L&W Model 121D Densometer were used. The densometer records the time required for a given volume of gas (e.g., air, which has been conventionally used in this test, at 100 cm 3 3) to pass through an area of 1 inch in diameter of the film (and a specific pressure gradient, conventionally about 4.9 inches of water). The test procedure conformed to the TAPPI T-460 OM-11 method. Prior to the test, a verification test was performed by using a calibration plate having a known value of Gurley air permeability (19.2 seconds). The calibration plate allowed 100 cm 3 3 of air to pass through within 19.2 seconds. When the verification was complete, the microporous film specimens were tested. Even though the permeability depends on the area and pressure of the test specimen, these values are standardized with respect to the equipment, so the results are conventionally reported in s / 100 cm 3reported or sometimes simply reported as seconds, s (since samples of air at 100 cm 3 are also standardized). In this specification, Gurley porosity is described as Gurley air permeability and is reported as seconds / 100 cm 3 as is common in the art.

[0140] Grab Tensile Test The Grab Tensile Test was performed on an Instron Tester. The test procedure followed the ASTM D 5034 - 09 (2013) test method. The grab test specimens were gripped at the center of the specimen width to ensure unequal upper and lower parts being gripped. The crosshead speed was 12 inches per minute for all experiments. The Instron recorded the tensile strength (Newtons per unit width) and elongation (%) at the peak load.

[0141] Nuclear Magnetic Resonance (NMR) Spectroscopy Approximately 0.25 g of the sample was cut into small pieces and inserted into a 10 mm NMR tube. 2.6 ml of tetrachloroethane - d2 (TCEd2) containing 10 mM of a relaxant was added. The sample was then heated at 115°C. 13 13C NMR and diffusion measurements (translational diffusion) (to confirm that it is a homopolymer or blend) were performed on a Bruker 600 MHz spectrometer equipped with a 10 mm cryogenic probe using the following parameters: Repetition time: 15 seconds Number of scans: 1536 90° pulse: 12 ms Spectral width: 240 ppm Temperature: 115°C Spectral center: 90 ppm

[0142] Gel Permeation Chromatography (GPC) The sample was dissolved in the carrier liquid at a concentration of 1 mg / ml by shaking in 1,2,4-trichlorobenzene (TCB) containing 200 ppm of butylated hydroxytoluene (BHT) at 160 °C for 2 hours. GPC was performed on a PolymerChar high-temperature LC system operated in GPC mode. The injection volume was 300 μl. The flow rate was 1 ml / min. The eluent was TCB containing 200 ppm of BHT. Separation was carried out on two 7.5 × 300 mm PL-Gel Mixed-B columns (Agilent). An integrated IR5 detector was used for detection in PolymerChar HTLC (high-temperature liquid chromatography). A series of 16 polystyrene (PS) narrow molecular weight distribution standards (Agilent Corporation) was used for molecular weight calibration. The calibration range was 0.58 - 3750 kg / mol, and the calibration curve was a least-squares fit to a third-degree polynomial. Thus, the reported molecular weights are PS equivalent molecular weight values. Once the verification was complete, the microporous film samples were tested.

[0143] Microbial barrier test (ASTM F2638-18) The microbial barrier test (ASTM F2638-18) uses aerosol filtration to measure the performance of porous packaging materials as surrogate microbial barriers and is applicable to porous materials used to package devices for terminal sterilization medical use. The aerosol filtration performance of the porous packaging material is measured by generating a defined aerosol of 1.0 μm particles and evaluating the filtration efficiency of the material using a single or dual particle counter. The test result is calculated as %P max , i.e., the maximum percent concentration of particles (particles that remain aerosolized after passing through the test piece) in the filtrate aerosol when the test piece is tested over a range of pressure differences or air flow rates. P max The lower the value, the better the barrier to particulate matter or microorganisms.

[0144] Mooney viscosity The Mooney viscosity (ML 1+4 at 125°C) was measured using an Alpha MV 2000 Mooney viscometer in accordance with the ASTM D1646-07 standard method. Here, L indicates the use of a large (i.e., standard) rotor, 1 is the preheating time in minutes, 4 is the reading time in minutes, and 125°C is the test temperature. The Mooney viscosity is generally used to measure the viscosity of raw rubber / elastomers and to determine the quality characteristics of both natural and synthetic rubbers. A Mooney viscometer consists of rotating a serrated rotor embedded in a rubber test specimen housed in a sealed pressurized cavity. From its constant speed, the rotor experiences a given resistance to rotation, which is recorded as torque in N-m. ASTM D1646 describes an algorithm used to convert this torque to Mooney units (MU). The Mooney viscosity is affected by the method of preparation of the rubber / elastomer and the storage conditions prior to testing. The test specimen consists of two discs of elastomer with a diameter of 50 mm and a thickness of approximately 6 mm sufficient to completely fill the cavity of the viscometer. The sample should contain no air and no pockets that can trap air on the rotor and die surfaces. A hole is drilled through the center of one disc to insert the rotor stem. The test specimen should be allowed to stand at standard laboratory temperature for at least 30 minutes before testing and tested within 24 hours after homogenization. In a Mooney viscosity test, a large rotor should be used as long as the Mooney viscosity does not exceed the torque capacity of the instrument. Adjust the closed die with the rotor in place to the test temperature. The temperatures of the two dies should be within 0.5°C of each other. While the viscometer is operating without loading the rotor in place, adjust the torque indicator to a zero reading value. Then, stop the rotation of the disc. This adjustment should be made with the die open for mechanical ones with a rotor release spring. Remove the hot rotor for a properly adjusted cavity, quickly insert the stem through the center of one of the test specimens, and replace the rotor of the viscometer. Place the second test specimen at the center of the rotor, close the die immediately, and start the timer. Heat the sample precisely for 1 minute in the closed Mooney viscometer test cavity and then start the motor driving the rotor. The viscosity reading values should be recorded continuously. The operating time should never be less than 2 minutes.

[0145] Example 1 This example investigates the influence of annealing before stretching on a homopolymer PP film. Table 1 shows the stretching conditions of the homopolymer polypropylene, PP H314, after stretching and the corresponding porosity and pore size (median pore size) for both the case where annealing was carried out (before stretching) and the case where it was not. The notation CSXX-HSYY means that the film was subjected to XX% cold stretching followed by YY% hot stretching.

[0146] [Table 1]

[0147] Table 1 shows that annealing at a temperature near the melting point of PP for a long time is required to achieve the desired pore size and porosity. The PP H314 sample without annealing did not change to white after stretching, and correspondingly, as shown in Table 1, the film showed very low porosity (2 - 4%). In contrast, when annealing at 150 °C for 24 hours was carried out, after the same stretching conditions, the film immediately changed to white and a porosity of 20 - 24% was obtained. Similar results were obtained for films of homopolymer PE (HDPE 6400).

[0148] Furthermore, in order to confirm whether polymer incompatibility aids pore formation when no prior annealing is performed on the film, blends of the homopolymer PE (HDPE 6400) and the homopolymer PP (PP H314) were investigated. Blends of the homopolymer polypropylene and the homopolymer polyethylene were prepared in a twin-screw extruder and then extrusion molded into films. Without performing an annealing step, extruded films with blend ratios of 100:0, 90:10, 80:20, 70:30, 50:50, 30:70, 20:80, 10:90, and 0:100 (homopolymer polyethylene vs. homopolymer polypropylene) were prepared as described above and then subjected to continuous cold (CS) and hot (HS) uniaxial stretching (25% cold stretching at room temperature, 100 mm / sec, followed by 100% hot stretching at 100°C, 5 mm / sec). Again, when annealing was not performed, pore formation was not observed for the films of these PP / PE homopolymer blends.

[0149] Long annealing times involve problems from the perspective of the desired objectives for running a continuous manufacturing line to produce microporous films. Ideally, a continuous extrusion and pore formation process in one continuous manufacturing line that does not require a holding period for extending the annealing step is preferred.

[0150] Example 2 One object of the present invention is to produce a film capable of pore formation during film stretching without requiring any thermal annealing step before or after film stretching. By eliminating the annealing step of the prior art process, a continuous manufacturing process becomes possible. In this example, pore formation in homopolymer polypropylene induced by microphase separation was investigated in order to reduce the required annealing time or, preferably, to completely eliminate the annealing step from a similar manufacturing process of polyethylene or polypropylene homopolymers. For this reason, a PP copolymer composed of homopolymer polypropylene (PP) chain segments and ethylene-propylene (EP) copolymer chain segments was prepared and extrusion molded into a film.

[0151] To define the effective parameters and ranges of the present invention, four different reactor grades of PP copolymers were evaluated. The characteristics of the various PP copolymers are shown in Table 2 (melt flow rate, EP copolymer content (the isotactic PP content is 100 - EP content), and ethylene and propylene contents in the EP copolymer chain segments)).

[0152] [Table 2]

[0153] The films of these PP copolymers were prepared as described above and then subjected to continuous cold (CS) and hot (HS) uniaxial stretching (25% CS at 100 mm / sec, followed by 100% HS at 100 °C and 5 mm / sec). The film characteristics (average pore size, porosity, and WVTR) are shown in Table 3.

[0154] [Table 3]

[0155] The films of comparative examples PP TI4020N and PP INSPIRE® 114 had very low average pore diameters (8 - 12 nm) and very low film porosities (7 - 10%), and it was found that these film characteristics corresponded to very low water vapor transmission rates and very low water vapor permeabilities. Both samples were inappropriate for the intended purpose as breathable films. On the other hand, the films of PP C700 - 35N and PP C7054 - 07NA of the examples of the present invention had average pore diameters and film porosities in a target range similar to that of commercially available Tyvek®, and film characteristics such as water vapor transmission rate and water vapor permeability suggesting that both of these samples were suitable as breathable films.

[0156] Example 3 PP copolymers containing PP C7054-07NA resin, homopolymer polypropylene chain segments and ethylene-propylene copolymer chain segments were selected for further study to optimize the stretching conditions in order to investigate the range of characteristics of the microporous films available by this approach. The initial thickness of the PP C7054-07NA resin film before stretching was 203 μm.

[0157] As described above, films were prepared from PP C7054-07NA and subjected to continuous cold and hot uniaxial stretching under various process conditions listed in Table 4. Then, the film characteristics (pore size and porosity) were evaluated to confirm the actual process parameters.

[0158]

Table 4

[0159]

Table 5

[0160] Table 4 shows that the stretching conditions can be optimized to adjust the desired porosity and average pore size. (By controlling two of the three variables to be constant while changing the third variable), a number of comparisons can be made regarding specific stretching variables (cold stretch ratio (%), hot stretch ratio (%) and hot stretch temperature (°C)). For example, one such series is illustrated by Samples 1-4, which show the effect of the hot stretch temperature (°C) when the ranges of room temperature cold stretch and hot stretch are held constant (25% and 50% respectively). As the hot stretch temperature increases in the temperature range of 60-120 °C, the porosity and pore size (median pore size) increase. Another such series is illustrated by Samples 11-16, which show the effect of the hot stretch ratio at 100 °C after 25% room temperature cold stretch. Again, as the hot stretch ratio increases in the range of 25-100%, the porosity and pore size (median pore size) increase, but the trend reverses at higher hot stretch ratios (200 or 300%).

[0161] Example 4 This example investigates the performance of a uniaxially stretched microporous film of a PP copolymer. Example 3 demonstrated the influence of film stretching conditions on pore formation (with respect to porosity (%) and average pore diameter (nm)). In Table 4 above, since the degree of thermal stretching clearly has a significant influence on porosity and average pore diameter, this series (Samples 11 - 14) was selected for further study including physical properties and performance data.

[0162] The microporous film of PP C7054 - 07NA resin was subjected to the same cold stretching degree (25%) at 25°C, but the range of the degree of thermal stretching at 100°C was 25% - 100%. The initial thickness of the PP C7054 - 07NA resin film before stretching was 203 μm, and the final film thickness after stretching under various stretching conditions is listed in Table 5.

[0163] Mercury porosimetry was used to measure the average pore diameter and porosity of this series of stretched PP C7054 - 07NA films, and the results are summarized in Tables 4 and 5. The pore distribution of the PP C7054 - 07NA microporous film for this series is illustrated in Figure 1B and compared with that of Tyvek® in Figure 1A. Note that the y - axis scale is different in Figure 1A compared to that shown in Figure 1B.

[0164]

Table 6

[0165] Table 5 and Figures 1A and 1B show that under appropriate stretching conditions, the PP C7054 - 07NA microporous film can exhibit a larger pore diameter and porosity than Tyvek® housewrap.

[0166]

Table 7

[0167] As shown above (Table 4, Example 3), in the heat drawing range of 25 to 100%, when the heat drawing range increases, both the porosity and the pore diameter (average pore diameter) increase. Also, it is expected that an increase in the water vapor permeability ("perm") is induced by the increase in both the porosity and the average pore diameter (Table 6). As shown in Table 6, by adjusting the pore diameter of the PP C7054-07NA microporous film, the water vapor permeability can vary from 14 perm to 82 perm (ASTM E96). It should be noted that the water vapor permeability of Tyvek® house wrap having a similar thickness is about 60 perm. Table 6 also shows the Gurley air permeability of the PP C7054-07NA microporous film, indicating that the C7054-07NA microporous film can have a better barrier against air flow. Therefore, they can be a good option for improving the energy efficiency of a house, for example, compared to Tyvek®.

[0168] Example 5 This example considers the morphology of the PP copolymer film. A film (PP / PE) with microphase separation that results in incompatible regions of polyethylene within the polypropylene matrix is produced by a prior art blend of homopolymer polypropylene and a minor component of homopolymer polyethylene. The polypropylene copolymers disclosed herein were cast as films and investigated for the purpose of producing microphase separation within the incompatible EP regions within the polymer film. Such microphase separation results in inclusion phases within the incompatible regions. The morphology of these films before and after drawing was investigated by SEM and TEM.

[0169] Figure 2 shows the SEM images of the film cross-sections. Figure 2A shows the cross-section of the as-received PP C7054-07NA film (indicated by the 20-μm scale bar), and Figures 2B and 2C show the drawn PP C7054-07NA films by 25% cold drawing and 50% hot drawing (100 °C). Compared with the 5-μm scale bar in Figure 2C, Figure 2B is indicated by the 20-μm scale bar. In the as-received film of PP C7054-07NA in Figure 2A, microphase separation and related domain formation can be confirmed in the region diameters ranging from several hundred nanometers to about 3 μm. In Figures 2B and 2C, the PP C7054-07NA films were directly subjected to cold drawing (25%) at a drawing speed of 100 mm / s, followed by hot drawing at a drawing speed of 5 mm / s and a temperature of 100 °C without annealing. As can be seen from the SEM images of the film cross-sections in Figures 2B and 2C, many pores are formed by 25% cold drawing and 50% hot drawing.

[0170] Figure 3 shows the SEM images of the film surfaces. Figures 3A and 3B show the as-received PP C7054-07NA film, and Figure 3A is indicated by the 20-μm scale bar compared with the 10-μm scale bar in Figure 3B. Figures 3C and 3D show the drawn PP C7054-07NA films by 25% cold drawing at a drawing speed of 100 mm / s, followed by 50% hot drawing (100 °C) at a drawing speed of 5 mm / s, and Figure 3C is indicated by the 20-μm scale bar compared with the 10-μm scale bar in Figure 3D. Before drawing, the film surface is very smooth (Figures 3A and 3B). In contrast, pores can be clearly observed on the surface of the drawn PP C7054-07NA films (Figures 3C and 3D).

[0171] Figure 4 shows TEM images of the film before and after stretching. Figures 4A and 4B show the PP C7054-07NA film before and after stretching, respectively (as described above, 25% CS; 50% HS), and Figures 4A and 4B are both shown by a 1 micron scale bar. Figures 4C and 4D show the PP INSPIRE® 114 film before and after stretching, respectively (as described above, 25% CS; 50% HS), and Figures 4C and 4D are shown by a 0.2 micron scale bar.

[0172] In the unstretched film of PP C7054-07NA in Figure 4A, microphase separation and related domain formation can be easily confirmed in the region diameter range of several hundred nanometers to about 3 microns. The TEM images in Figures 4A and 4B suggest that the cavitation process is nucleated in the ethylene-propylene (EP) region with respect to the PP C7054-07NA film. Without wishing to be bound by theory, the inclusion morphology of the PP microphase in the EP region within the PP matrix enables the stretching force to be effectively transferred to the microphase region, whereby the microphase region is considered to be divided into small fragments and initiate pore formation and growth. In contrast, after stretching of the PP INSPIRE® 114 film, the EP region of the PP INSPIRE® 114 film only showed elongation along the stretching direction (Figures 4E and 4F). There was no pore formation.

[0173] Further evidence of the different responses to stretching between the films of PP C7054-07NA or PP C700-35N compared to PP TI4020N or PP INSPIRE® 114 was observed in wide-angle X-ray scattering (WAXS) studies. The WAXS pattern is related to the Bragg diffraction of X-rays by the polypropylene crystalline lattice and provides information on the composition of the crystal, the orientation of the crystal, and the relative amount of crystallinity.

[0174] Figure 5 shows the WAXS patterns of films of two different PP copolymers, PP C7054-07NA and PP TI4020N. Samples for each copolymer included an unstretched film and samples stretched by 25% cold drawing at room temperature and 100% hot drawing at 100 °C. No significant change in the crystal structure was observed for the PP C7054-07NA resin film between before and after stretching (Figures 5A and 5B, respectively). The same observation was made for the PP C700-35N resin film (not shown). As shown in Figures 5C and 5D, for the PP TI4020N resin film, significant orientation was observed due to the release of strong diffraction intensity in the (110), (040), (130), and (131) planes, resulting in rotation of the crystal structure and reorganization into a fibril structure. A similar observation was made for the PP INSPIRE® 114 resin film (not shown). From the above WAXS results, the stretching force was applied to the crystalline polypropylene structure of the PP TI4020N resin film and the PP INSPIRE® 114 resin film, but it was speculated that during the stretching process of the PP C7054-07NA resin and the PP C700-35N resin films, the stretching force moved to the EP phase to initiate and grow pores. Such a discrepancy results in high porosity for both the PP C7054-07NA resin and the PP C700-35N resin microporous films, but low porosity for both the PP TI4020N resin film and the PP INSPIRE® 114 resin microporous films.

[0175] Example 6 Pore formation via stretching of non-annealed films has been previously demonstrated using a PP copolymer (see the above PP C7054-07NA microporous film) (Examples 2 to 4 above). Blending this PP copolymer as the main component with homopolymer-PP, PP H314 (as the minor component) was also investigated (Table 7). The films were prepared as described above and stretched at stretching conditions: 25% cold stretching (room temperature) at a stretching rate of 100 mm / sec, followed by 100% hot stretching (100 °C) at a stretching rate of 5 mm / sec.

[0176]

Table 8

[0177] By increasing the amount of homopolymer-PP and blending it with the PP C7054-07NA copolymer, followed by cold and hot stretching processes, progressively lower porosity and smaller average pore diameters of the stretched microporous films were obtained until pore formation was no longer achieved with an additional 40% of homopolymer-PP.

[0178] Similarly, pore formation via stretching of non-annealed films has been previously demonstrated using another PP copolymer (see the PP C700-35N microporous film, Table 3) (Example 2). Blending this PP copolymer as the main component with homopolymer-PP, PP H314 (as the minor component) was also investigated (Table 8).

[0179]

Table 9

[0180] Inclusion morphology also decreased by using a twin-screw extruder to compound 20 wt% of homopolymer PP H314 with PP C7054-07NA, followed by film production. As a result, during stretching, most of the microphase regions extended only along the stretching direction (see, for example, the TEMs in Figures 6A and 6B).

[0181] The results for films from blends of PPC700-35N with homopolymer-PP were similar to those for films from blends of PPC7054-07NA with homopolymer-PP.

[0182] As noted above, pore formation via stretching of non-annealed films was demonstrated for the PP copolymer (see the PPC7054-07NA microporous film above). It was also demonstrated that this copolymer as the main component was further blended with a PP copolymer, PP TI4020N (as the minor component) to form pores via stretching of non-annealed films (Table 9).

[0183] [Table 10]

[0184] Blending PPC700-35N with PP TI4020N can also form a film that can be stretched (without performing pre-annealing) to produce a microporous film.

[0185] Other polymer blends were evaluated as follows: VERSIFY (registered trademark) 2000 resin (melt flow rate at 230 °C and 2.16 kg = 2 g / 10 min) is an ethylene-propylene random copolymer having a composition of 94% P / 6% E (propylene-rich). VERSIFY (registered trademark) 2400 resin (melt flow rate at 230 °C and 2.16 kg = 2 g / 10 min) is also an ethylene-propylene random copolymer having a composition of 86 wt% P / 14 wt% E (propylene-rich). In each case, two blend ratios (85:15 and 70:30) with the homopolymer PP (PP H314) were prepared. PP H314 was the main component in the total blend. The non-annealed films of these blends were subjected to the CS25-HS100 stretching conditions (described above). None of these PP / EP blends formed pores after the stretching process. This may be due to the high content of propylene segments in the VERSIFY (registered trademark) 2000 and VERSIFY (registered trademark) 2400 resins. The propylene segments have good compatibility with the PP matrix and thus cannot induce sufficient phase separation in the PP H314 resin.

[0186] The 13C04R21 experimental resin (melt flow rate at 230 °C and 2.16 kg = 18 g / 10 min) is an isotactic PP diblock copolymer having a 50:50 ratio of PP:EP components in the copolymer, and the EP copolymer block contains 14 wt% E and 86 wt% P (the total ethylene content of the resin is 7 wt%). Blends of the homopolymer PP (PP H314) and this diblock copolymer were prepared at ratios of 85:15, 80:20, 70:30, and 60:40 (major PP), and the non-annealed films were subjected to the CS25-HS100 stretching conditions (above). None of these PP / EP blends formed pores after the stretching process. The EP block in this experimental grade resin contains only 14 wt% ethylene, producing a PP-rich EP block. As a result, the EP block and the iPP block have good compatibility with the homopolymer PP resin, and thus it is considered that the EP block cannot initiate sufficient phase separation in the film.

[0187] INTUNE® D5545.00 (melt flow rate at 230 °C and 2.16 kg = 9.5 g / 10 min) is another isotactic PP diblock copolymer having a 50:50 ratio of PP:EP copolymer, but the EP copolymer block is ethylene-rich, containing 92 wt% E and 8 wt% P (the total ethylene content of the resin is 46 wt%). By stretching non-annealed films (CS25-HS100 stretching conditions of Example 6 above), only minimal pore formation was achieved: 13.6% porosity and an average pore diameter of 14.1 nm. The films of the diblock copolymer are not suitable for the desired purpose as a housewrap material. Blends of the homopolymer PP (PP H314) and this diblock copolymer were prepared at ratios of 85:15, 80:20, 70:30, and 60:40 (major PP), and the non-annealed films were subjected to the CS25-HS100 stretching conditions (above) of Example 6. None of these PP / EP copolymer blends formed pores after the stretching process.

[0188] NORDEL® 3722P is an EPDM (ethylene-propylene-diene monomer) copolymer having a composition of 28.5 wt% propylene, 71 wt% ethylene and 0.5 wt% ENB (ethylidene norbornene). Blend ratios of 90:10, 80:20 and 70:30 (polypropylene-rich), blends of the main homopolymer PP of NORDEL® 3722P with NORDEL® 3722P were investigated. The non-annealed films were subjected to the CS25-HS100 stretching conditions (above). None of these PP / EP copolymer blends formed pores after the stretching process.

[0189] In addition, ethylene acrylic acid (PRIMACOR® 1410 resin: 90.3 wt% E, 9.7 wt% acrylic acid) was evaluated (melt flow rate at 230 °C, 2.16 kg = 1.5 g / 10 min). The blend was 85 wt% PP H314 resin and 15 wt% PRIMACOR® 1410 resin. Under the same stretching conditions, this blend was unable to show pore formation. The PRIMACOR® 1410 resin was incompatible with the PP H314 resin and thus formed a completely separated interface between the two phases.

[0190] Example 7 This example examines the aging performance of non-thermally cured microporous films. In many prior art microporous films, degradation of properties has been observed after thermal aging (see, for example, Table 1 of U.S. Patent No. 3,801,404 showing progressive loss of nitrogen flux of a polypropylene microporous film at 65°C for 1 to 281 hours; and Table 2 of U.S. Patent No. 3,843,761 showing air flow rate loss rate of a polypropylene microporous film after 1 hour at 90°C). Thermal curing (annealing at a high temperature after stretching of a polyolefin film) has often been used in the prior art (such as U.S. Patent No. 3,679,538) to prevent loss of water vapor transmission performance during aging (for example, at 65°C). Non-thermally cured PP C7054-07NA MDO microporous films (uniaxially stretched, mechanically oriented) were aged at 65°C for various times in the range of 1 hour to 168 hours (Table 10).

[0191]

Table 11

[0192] As shown in Table 10, the water vapor permeability data did not change much over time. In the present invention, as indicated by the slight changes in wide-angle X-ray (WAXS) data of uniaxially stretched (MDO) PP C7054-07NA microporous films before and after stretching (Figs. 5A and 5B), the stretching force was transferred to the microphase rubber-like (ethylene-propylene copolymer) region and consumed to produce the microporous structure. In contrast, for comparative films, such as the PP TI4020N resin film, the crystal structure rotated and reorganized into a fibril structure, and significant orientation was observed in the WAXS data after stretching due to the emission of strong diffraction intensities in the (110), (040), (130), and (131) planes (Fig. 5D after stretching compared to Fig. 5C before stretching). This aging performance of the breathable films disclosed herein is distinguishable from other homopolymer polyolefin microporous films reported in the prior art where thermal curing is always required.

[0193] From a perspective other than air permeability, the same phenomenon of performance degradation after the heat curing step was investigated in U.S. Patent No. 3,843,761. In U.S. Patent No. 3,843,761, the film obtained from the heat curing step was compared with a control film that did not undergo the heat curing step. This reference concludes that the flow rate loss due to the heat curing step ranges from 44% to 88% for the prior art cold stretching / single heat stretching process, and the flow rate loss due to the heat curing step ranges from 24% to 37% for their novel cold stretching / multiple continuous heat stretching process.

[0194] To compare with the heat curing results disclosed in U.S. Patent No. 3,843,761, a PP C7054-07NA microporous film having the same degree of stretching as that disclosed in U.S. Patent No. 3,843,761 (see Table 11) was produced. In particular, the first sample, PP C7054-07NA-CS20-HS95, was stretched by 20% cold stretching at 100 mm / sec, followed by 95% heat stretching at 5 mm / sec and 100 °C. The second sample, PP C7054-07NA-CS40-HS75, was stretched by 40% cold stretching at 100 mm / sec, followed by 75% heat stretching at 5 mm / sec and 100 °C.

[0195]

Table 12

[0196] Then, these microporous films were subjected to the same heat curing step (90 °C for 1 hour) as the reference patent. The relative air permeability is calculated by the following formula.

Equation

[0197] Table 12 shows the relative air permeability of the microporous film (as defined above) comparing Gurley air permeability before and after heat curing at 90°C for 1 hour (for each type of film, four samples at four positions for each sample, and each entry in the table for relative air permeability is the average of four ratios determined from four measurements at four positions before and after heat curing).

[0198]

Table 13

[0199] From Table 12, it can be seen that the average relative air permeability is about 1.5 for both stretched films, and for the film of the present invention, different from the 24 - 88% flow rate loss disclosed in U.S. Patent No. 3,843,761, it shows that the (normal) air permeability increases by about 50% after heat curing. The porous structure of the polyolefin - based microporous film disclosed in the present invention can withstand the heat curing process.

[0200] The breathable film of the present invention can be prepared without an annealing step before stretching for manufacturing the microporous film, and furthermore, does not require any heat curing step even after pore formation. Further, if the heat curing step is desired for any reason, the film of the present invention does not suffer any loss of permeability compared to a film without the heat curing step.

[0201] Example 8 This example shows the performance of a biaxially stretched microporous film of a PP copolymer.

[0202] The PP C7054-07NA copolymer film was subjected to simultaneous biaxial stretching, specifically 25% cold stretching at a speed of 100 mm / second at room temperature and 50% hot stretching at 5 mm / second at 100 °C. As shown in Table 13, the biaxially stretched microporous film of PP C7054-07NA has a porosity of 34.7% and an average pore diameter of 44 nm. Correspondingly, the water vapor permeability for this microporous film is about 42 perm (Table 14), and after aging at 65 °C for 168 hours, the water vapor permeability increases to 60 perm (Table 14).

[0203]

Table 14

[0204]

Table 15

[0205] This example shows that biaxial stretching can also be used to produce microporous films.

[0206] Example 9 To conduct a proof-of-concept study of the roof film, a PP C7054-07NA film with a thickness of 762 μm (30 mils) was subjected to 25% cold stretching (CS) at 100 mm / second at room temperature and then 100% (150% for the second film) hot stretching (HS) at 5 mm / second at 100 °C. Pore size distribution data in the range of several tens of nanometers to several microns are shown in Figure 7. From Table 15, it can be seen that the PP C7054-07NA-CS25-HS100 with a thickness of about 660 μm (25.5 mils) has a porosity of 42.5% and results in a water vapor permeability of 58 perm, and the PP C7054-07NA-CS25-HS150 with a thickness of about 533 μm (20.6 mils) has a higher porosity of 55% and results in a water vapor permeability of 62 perm.

[0207]

Table 16

[0208] Useful porosity (e.g., greater than 25%) and permeability values (e.g., greater than 10 perm) can also be obtained from thicker 762 μm (30 mil) films, suggesting that the films of the present invention find utility in breathable roof membranes.

[0209] Example 10 For each end use, the stretch microporous PP copolymer films were evaluated for various combinations or degrees of air or water vapor permeability or barrier to microorganisms required for medical packaging films and active packaging. Table 16 shows the film thickness, basis weight, porosity, and pore size (average pore diameter) of the microporous films obtained from various stretching conditions.

[0210] [Table 17]

[0211] The same series of films were further investigated for their permeability characteristics (Table 17), physical properties (Table 18), and gas filling / evacuation rates (Table 19) when used as medical packages.

[0212] Table 17 shows the important barrier properties ( Gurley air permeability, water vapor transmission rate, and F2638 barrier to microorganisms) obtained for the same microporous films shown in Table 16.

[0213] [Table 18]

[0214] Table 17 shows data regarding the uniaxially stretched PP copolymer film, demonstrating that the permeability characteristics can be changed and controlled by changing the stretching conditions. The target ranges for various properties can be estimated by comparison with existing commercially available products for these applications (e.g., Tyvek® 1073B or medical grade paper), but since there are various end uses for films with various property balances, these are not exact targets (also, one or more of the properties of the commercially available products can significantly exceed the minimum target range required for that property). By using optimized stretching conditions or by using biaxially stretched films, the barrier against microorganisms (as shown by the F2638 P max value) is already within a commercially viable target range, and the target for Gurley air permeability (possibly about 10 - 100 seconds for some applications) must also be available. Some applications may require a specific hydrohead value (resistance to water pressure). As shown in Table 16, the porosity and average pore diameter were measured for Films 4 - 9, and the porosity did not vary much (43% - 53%), and the pore diameter was in the range of 70 nm - 108 nm. Although not shown in the table, Films 1 - 9 had a hydrohead value higher than 500 cmwc (cm of water column), easily exceeding the hydrohead value of Tyvek® 1073B (the hydrohead value of Tyvek® 1073B is about 150 cmwc).

[0215] In addition to the permeability characteristics, breathable films for medical films and active packaging also require appropriate physical properties regarding film strength such as tensile strength, tear strength, and elongation %. Table 18 summarizes such properties for the same series of breathable PP copolymer microporous films.

[0216]

Table 19

[0217] The stretching process conditions can be varied in order to control the film thickness / basis weight as well as other physical properties (such as tensile strength, tear strength and elongation). The physical properties are important in order to maintain the integrity of the package during transportation, sterilization and storage and to ensure that the packaging structure does not tear when the package is peeled open.

[0218] Compared to current technology, at least the tensile strength of these films appears to be sufficient for most medical and active packaging applications.

[0219] Medical packages are currently finding use as container packages that can be filled with a sterilizing agent gas (such as steam or ethylene oxide) in order to sterilize the package contents (such as medical devices or equipment). The package is filled with the sterilizing agent and then the contents remain with the sterilizing agent gas for the residence time of the sterilization process and then the gas is evacuated and the package is sealed with the sterilized device inside. The package material provides a barrier against bacteria, microorganisms and particulate matter so as to maintain the sterility of the medical device inside the package after sterilization until such a device is ready for use.

[0220] Table 19 investigates how the stretching process conditions can affect the fill / void time of the PP copolymer film.

[0221]

Table 20

[0222] In Table 19 above, the improvement in Gurley air permeability between the comparative film (immediately after cold drawing) and the film of the present invention ranges from 45,200 to 860 seconds, which represents a 20% improvement in the time for filling (or emptying) a medical package with gas. Even when a relatively modest improvement in Gurley air permeability does not match that of Tyvek® 1073B, it corresponds to a significant % improvement in the time for filling (or emptying) a medical package with gas, and when such medical packages are used for the sterilization of medical devices and equipment, Table 19 includes breathable film (1) and breathable film (2), which are hypothetical films having Gurley air permeabilities of 300 seconds and 100 seconds, respectively, to show that it can be converted into significant cost savings.

[0223] The PP copolymer microporous film described herein is well-suited as medical packaging. Compared to current polyethylene technology, the sterilization process can be carried out at a higher temperature due to the higher melting temperature of the PP copolymer film compared to the polyethylene film (for example, the typical melting temperature of high-density polyethylene is about 125 - 130 °C according to DSC, while the typical melting temperature of the PP-EP copolymer of the present invention disclosed herein is about 168 °C according to DSC). Furthermore, the PP copolymer film can be easily thermoformed (enabling packaging that can be easily customized for various medical devices and equipment) and is heat-sealable (for easily heat-sealing sterilized packs).

[0224] When ranges are used herein with respect to physical properties such as temperature ranges and pressure ranges or chemical properties such as monomer or copolymer content, all combinations and sub-combinations of the ranges as well as specific embodiments therein are intended to be included.

[0225] The disclosure of each patent, patent application, and publication cited or described herein is hereby incorporated by reference in its entirety.

[0226] Those skilled in the art will understand that many variations and modifications can be made to the preferred embodiments of the present invention and that such variations and modifications can be made without departing from the spirit of the present invention. Accordingly, the appended claims are intended to cover all such equivalent variations that fall within the true spirit and scope of the present invention.

[0227] Reference Example A number of PP copolymer films having various thicknesses were extrusion cast onto a chill roll set at a temperature of 80°C using a 2.5-inch single-screw extruder and a 24-inch wide cast die manufactured by Davis-Standard, LLC, and films having a smooth surface were produced. The base resin is PP C7054-07NA, a polypropylene copolymer available from Braskem American, Inc. (product code C7054-07NA). The extruder was maintained at a constant temperature profile of 460°F (238°C), and the chill roll temperature was heated by heating oil. The thicknesses of the obtained films are summarized in Table 20.

[0228] [Table 21]

[0229] Example 11 Next, using a multi-stage cold drawing process as shown in FIG. 8, samples of the individual films in Table 20 were drawn in the machine direction (MDO - machine direction orientation). Each sample of the PP copolymer film from Table 20 was attached to the unwind section 20 and guided by eleven drawing rollers (1 - 11) including a pre-drawing section 23, a drawing section 24, and an annealing section 25, and then wound back onto the wind-up section 21. Next, pressure was applied to the film to prevent slippage during drawing by closing the nip rollers. The roller speeds of rollers 3 - 7 were slowly increased, and the film was drawn 50% or 100% at 25°C. During the drawing process, the film changed from a semi-transparent color to white, which indicates initial pore formation. Then, in the annealing section 25, the cold-drawn film was heated at 140°C by rollers 9 - 11 to fix the pore structure induced by the cold-drawing step. Then, the film was cooled and wound back onto the wind-up machine. The measured properties of the final film are summarized in Table 21. The cold draw ratio is defined as (total roller speed ratio - 1) × 100%, and the total roll speed ratio is the result of multiplying together all the roller speed ratios from (roller 2 / roller 1 to roller 8 / roller 7).

[0230]

Table 22

[0231] Next, using the same multi-step process shown in FIG. 8, the MDO cold-drawn film was further thermally drawn in the machine direction (MDO). However, with respect to the thermal drawing, the process included a pre-thermal drawing section 23, a thermal drawing section 24, and an annealing section 25. Each of the MDO cold-drawn films was attached to the unwind section, guided by 11 drawing rollers, and wound back onto the other winder section 21. In this process, the first 8 rollers were set to a thermal drawing temperature of 135°C. To prevent slippage during drawing by applying pressure to the film, the nip rollers were closed, and then the roller speeds of rollers 5-8 were slowly increased to draw the film by 50% or 100% at 135°C. After completion of the thermal drawing step, annealing was performed on the film at 140°C on rollers 9-11 to reduce film shrinkage. The film was then cooled by the winding device section 22 and wound back into a roll state. The degree of thermal drawing is defined as (total roller speed ratio - 1)×100%, and the total roller speed ratio is the result of multiplying together all the roller speed ratios (from roller 5 / roller 4 to roller 8 / roller 7). At the completion of MDO thermal drawing, it can be seen from Table 22 that the porosity and average pore diameter of the PP film increased. Thereby, a higher water vapor permeability and a lower Gurley air permeability are produced.

[0232]

Table 23

[0233] Example 12 To explain that thermal drawing may have an adverse effect on pore formation and air and water vapor permeability, the above cold and thermal drawing processes were applied to a sample of Film 1 that was cold drawn by 122% in the machine direction at 25°C and subsequently thermally drawn by 103% - 405% in the machine direction. As shown in Table 23, the porosity and permeability of the film deteriorated with drawing at higher temperatures. As a result, biaxial drawing was proposed to further increase the porosity and pore size, thereby obtaining a higher water vapor permeability and a lower Gurley air permeability.

[0234]

Table 24

[0235] Example 13 Next, the selection of the MDO cold and hot drawn film of Example 11 was further hot drawn in the transverse direction using a process as shown in FIG. 9, which included an unwind section 41, a multi-zone oven 50 with a preheating section 43, a TDO (transverse direction orientation) drawing section 44, an annealing section 45, and a cooling zone 46. The TDO line had a feed width in the range of 127 mm to 1,016 mm between clips and an exit width range of 203 mm to 2,184 mm between clips for stretching the film in the transverse direction. The TDO clips were able to hold a wide range of materials having a film thickness range of 25 μm to 2.54 mm. Following the heated regions (43, 44, and 45), there was a 1.5 m long cooling zone 46 with circulating outside air. After the TDO oven was preheated to the target temperature (135°C), the MDO drawn film was attached to the unwind and guided through the feed section of the TDO line. The film was gradually gripped by the clips and pulled through the preheating region at the same width. Then, the film was drawn in the transverse direction until the TDO target draw ratio was reached. At the completion of the draw, the film was passed through the annealing section 45 at 140°C and subsequently quenched by the circulating outside air in the cooling zone 46. Thereafter, the drawn film was guided through a roll stack and wound back onto the winder section 42. To simplify the test, the line speed was fixed at 2 m / min. The TDO draw ratio varied from 50% to 400%. Table 24 shows the drawing conditions and properties of the biaxially drawn PP breathable films prepared by MDO cold drawing, MDO hot drawing, and TDO hot drawing. All samples had a hydrohead higher than 300. These experiments showed that biaxial drawing was very effective in additional opening of the pores in the film. It can be seen from Table 24 that many of the biaxially drawn films had a porosity close to 70% and an average pore diameter larger than 200 nm. Correspondingly, most samples had a Gurley porosity of less than 100 seconds / 100 cc, some samples were in the range of 20 - 30 seconds / 100 cc, but many samples had a water vapor permeability higher than 100 perm. At the same time, although not shown in the table, all of the films had a hydrohead higher than 300 cm and showed good water resistance.Furthermore, the microbial barrier (%Pmax) measured by F2638 shows very good results (well within the target range).

[0236]

Table 25

[0237] Example 14 Table 25 shows the stretching conditions and properties of biaxially stretched PP breathable films prepared by MDO cold stretching followed by TDO hot stretching. Even without MDO hot stretching, very high porosity can be achieved. Also, the porosity and average pore diameter continued to increase as the TDO stretch ratio increased. Correspondingly, these PP breathable films exhibit comparable water vapor transmission rates, Gurley air permeabilities, and microbial barriers.

[0238]

Table 26

[0239] Example 15 An important property for a waterproof and breathable roof film is that it must pass a hydrohead test where it resists water at least 30 meters for 30 minutes. Stretch films were selected and tested for use as roof films. As can be seen from Table 26, all samples were manufactured by cold and hot stretching and passed the hydrohead test. These MDO samples have film thicknesses in the range of 0.19 mm to 0.53 mm and show water vapor transmission rates (WVTR) in the range of 29.1 perm to 76.7 perm. Biaxially stretched samples manufactured by cold MDO stretching followed by hot TDO stretching did not pass the hydrohead test due to more interconnected pores created by the biaxial stretching process.

[0240]

Table 27

[0241] Example 16 Polypropylene (PP) film samples were produced by cold and hot MDO stretching and tested for use as underlays. All samples shown in Table 27 passed the water resistance (W1), durability after aging (EN 1297 & EN 1296), flexibility at low temperatures (≦ -20 °C) and the cross-drop test (TU Berlin). However, from Table 27, it can be seen that samples 16a and 16b had low nail tear strength properties due to the low film thickness after stretching. Samples 16c and 16d show that acceptable nail tear strength can be achieved by increasing the film thickness. Samples 16e, 16f and 16g show other possible solutions of laminating thinner films with a grid or non-woven film. 16e is laminated to a D&L grid, 16f is a laminate with Thermanet® and 16g is laminated to a spunbond PP non-woven fabric, and the characteristic data of these laminates are shown in Table 27. These laminated films demonstrated a significant improvement in nail tear strength.

[0242]

Table 28

[0243] Example 17 In addition to the additional particulate barrier test with the TSI-8130 automated filter tester, microbiological barrier tests were collected in the selection of films from Examples 13 and 14 according to ASTM F2638. The data obtained are shown in Table 28. Biaxial stretching enables an increase in porosity and average pore diameter, and thus leads to a lower Gurley air permeability of less than 100 s / 100 cm 3 down to. All biaxially stretched samples showed a very good microbiological barrier (< 0.25% Pmax) within the target range. Furthermore, the burst pressure measured by the hydrohead test was higher than 5 meters for all biaxially stretched PP breathable films.

[0244]

Table 29

[0245] Example 18 This is an example of the preparation of a PP copolymer film further containing an ethylene-propylene elastomer.

[0246] The (a) polypropylene copolymer used was a reactor-grade PP copolymer purchased from Braskem, known as C7054-07 NA polypropylene (PP C7054-07 NA). It contained 32.9 wt% ethylene-propylene copolymer, and the ethylene content in the ethylene-propylene copolymer was 49.7 wt%. It had a density of 0.9 g / cm 3 and a melt index of 7 g / 10 min at 230 °C and a load of 2.16 kg. The number average molecular weight (Mn) of PP C7054-07NA was 58,000, and the weight average molecular weight (Mw) was 295,000.

[0247] The (b) ethylene-propylene elastomer used was Vistalon™ 785, an ethylene-propylene copolymer rubber (EPR) obtained from ExxonMobil Chemical. This is an amorphous copolymer of ethylene and propylene having a low Mooney viscosity, a low ethylene content, and a narrow molecular weight distribution. It contained an ethylene content of 49 wt% (by ASTM D3900A) and had a Mooney viscosity of 30 MU (by ASTM D1646). The PP copolymer was compounded with the EP elastomer to produce a modified compound mixture for subsequent processing by continuous cold and hot stretching.

[0248] The PP copolymer and EPR were compounded together using a 43 mm co-rotating twin-screw extruder. The PP copolymer was fed into the first barrel of the extruder operating at 250 rpm and pre-melted by the co-rotating screw before contacting the EPR. To assist in processing and enable metering of the EPR, the EPR was ground using a 4-inch (101.6 mm) Bonnot extruder, preheated, and then metered into the twin-screw extruder via a gear pump and joined to the PP melt in barrel 3. The EPR was measured at 112 °C immediately prior to the gear pump. The PP / EPR mixture was then conveyed through a series of mixing elements with the barrel temperature maintained at 200 °C. The actual melt temperature was monitored during operation and raised from 170 °C in barrel 5 to a peak temperature just below 245 °C in barrel 10. Prior to pumping through the die in barrel 12, a water-ring vacuum of -27 inHg was applied in barrel 11 to remove volatiles. The resulting product was collected from an underwater pelletization system operating at 450 - 550 psig with a die heated to 220 °C. The composition, compounding conditions, EPR rubber concentration, and DSC results are summarized in Table 29.

[0249]

Table 30

[0250] Next, a PP copolymer film was produced on a film casting line consisting of a 1-inch single-screw extruder from Davis-Standard and a 6-inch wide cast die. The cast film was produced from the above materials (see Table 1) in a range of thicknesses by controlling the speed of the single-screw and thus the throughput, and adjusting the roller speed for an overall line speed in the range of 1 - 10 ft / min. A melt filter pack with a stack of 150 / 200 / 150 mesh screens was used in-line to remove gels from the melt stream before cooling to 200 °C at the die. The film from the die was cast onto a temperature-controlled cooling roll at 50 °C to ensure good film quality before winding onto a 3-inch core at the winding station. A 10-mil film was cast from R10 and a 20-mil film was cast from R30.

[0251] The film morphology was investigated using TEM. Figure 10 is a TEM image of as-cast film prior to any stretching, made from a polypropylene copolymer containing (a) polypropylene homopolymer chain segments and ethylene-containing copolymer chain segments, and (b) having no ethylene-propylene elastomer. This figure shows an encapsulated morphology where the matrix PP material is contained inside the EP microphase domains. This particular morphology enables the transfer of stretching force to break the microphase domains and thus initiate and grow pore formation during stretching. Figure 11 is a TEM image of as-cast film R10 prior to any stretching, made from 90 weight percent of a polypropylene copolymer containing (a) polypropylene homopolymer chain segments and ethylene-containing copolymer chain segments and (b) 10 weight percent of ethylene-propylene elastomer. The encapsulated morphology remained intact and the domain size increased slightly. Figure 12 is a TEM image of as-cast film R30 prior to any stretching, made from 70 weight percent of a polypropylene copolymer containing (a) polypropylene homopolymer chain segments and ethylene-containing copolymer chain segments and (b) 30 weight percent of ethylene-propylene elastomer. When the EPR content was further increased for this film, the domain size increased significantly, but the encapsulated morphology still persisted.

[0252] Next, the cast film samples were stretched in the machine direction (MDO - machine direction orientation) using a multi - stage cold stretching process. Each sample of the PP / EPR film was attached to an unwinder, guided through 11 stretching rollers (1 - 11) equipped with a pre - stretching section, a stretching section, and an annealing section, and then wound back onto a winding section. Next, pressure was applied to the film to prevent slippage during stretching by closing the nip rollers. The roller speeds of rollers 3 - 7 were slowly increased, and the film was stretched by 50% at 25°C. During the stretching process, the film changed from a semi - transparent color to white, indicating initial pore formation. Then, in the annealing section 25, the cold - stretched film was heated at 135°C by rollers 9 - 11 to fix the pore structure induced by the cold - stretching step. The film was then cooled and wound back onto a winder. The cold - stretch ratio is defined as (total roller speed ratio - 1)×100%, and the total roll speed ratio is the result of multiplying together all the roller speed ratios (from roller 2 / roller 1 to roller 8 / roller 7).

[0253] Next, using the same multi - stage process, the MDO cold - stretched film was further heat - stretched in the machine direction (MDO). However, for the heat - stretching, the process included a pre - heat - stretching section, a heat - stretching section, and an annealing section. Each of the MDO cold - stretched films was attached to an unwinder section, guided by 11 stretching rollers, and wound back onto another winding section. In this process, the first 8 rollers were set at a heat - stretching temperature of 130°C. Pressure was applied to the film to prevent slippage during stretching by closing the nip rollers, and then the roller speeds of rollers 5 - 8 were slowly increased, and the film was stretched by 50% at 130°C. After completion of the heat - stretching step, annealing was performed on the film at 135°C by rollers 9 - 11 to reduce film shrinkage. The film was then cooled at the winding equipment section and wound back into a roll state. The heat - stretch ratio is defined as (total roller speed ratio - 1)×100%, and the total roll speed ratio is the result of multiplying together all the roller speed ratios (from roller 5 / roller 4 to roller 8 / roller 7).

[0254] Table 30 shows the stretching conditions, water vapor permeability, air permeability, porosity, and average pore diameter of the PP / EPR films compared with the PP films. All of these films have the same degree of cold stretching (50%) and the same degree of heat stretching (50%). The water vapor permeability of the PP-22 mil film is 52 ppm, and the water vapor permeabilities of the R10-10 mil and R30-20 mil films are 48.2 ppm and 27.5 ppm, respectively. It was confirmed that good water vapor permeability can be maintained even after adding EPR rubber to the PP film. The Gurley air permeability of the R10-10 mil is lower than that of the PP-22 mil, which may be due to the fact that the R10-10 mil has a thinner thickness. The high concentration of EPR in the R30-20 mil film gives a very high Gurley air permeability.

[0255]

Table 31

[0256] Table 31 summarizes the hydrohead, tensile strength, elongation at break, elastic modulus, and trapezoidal tear data of the PP / EPR films compared with the PP films. Both the R10-10 mil and R30-20 mil films produced by adding EPR to PP had lower elastic moduli than the PP-20 mil film. The addition of EPR to the PP film also improved the tear strength of the film. The trapezoidal tear (maximum load) of the R30-20 mil film was more than twice that of the PP-22 mil film.

[0257] The addition of EPR also did not significantly affect other film properties such as tensile strength. The elongation at break of the R30-20 mil was twice that of the PP-20 mil film, and the elongation at break of the R10-10 mil was slightly lower than that of the PP-20 mil film, which may be related to the smaller film thickness of the R10-10 mil (greater data variation). All of these films also showed excellent water retention (hydrohead over 300 cm).

[0258] In other words, by incorporating EPR into the PP film, the toughness and tear strength of the PP breathable film can be significantly improved while maintaining water vapor permeability and water retention.

[0259]

Table 32

[0260] Example 19 The heat weldability of the microporous film of Example 18 without the applied adhesive was examined. The edges of two samples of the R30 - 20 mil microporous film were overlapped and welded by the application of hot air (welding temperature 250 °C). Similarly, the edges of two samples of the PP - 22 mil microporous film were overlapped and welded in the same manner by the application of hot air. The overall appearance of the two welded samples showed that the R30 - 20 mil film sample shown in Figure 13 exhibited better visual sealing performance than the PP - 22 mil film sample in Figure 14. The PP film without EPR rubber was fragile and cracked after welding, while incorporating EPR rubber into the PP breathable film (R30 - 20 mil film) made welding easier and the welded area more tough compared to the PP microporous film without EPR rubber.

[0261] Example 20 Next, the cold - drawn and then heat - drawn film in the machine direction (MDO) of Example 18 was further heat - drawn using the processing and equipment described in Example 13 and shown in Figure 9, including the unwind section 41; the pre - heat section 43, the TDO (transverse direction orientation) draw section 44, the annealing section 45, and the cooling region 46 of the multi - zone oven 50; and the winding section 42; however, the TDO oven was pre - heated to 130 °C and the annealing section 45 was set at 135 °C.

[0262] The general properties of the biaxially drawn film (including the increase in other porosity), and the degree of difference in properties between the film in the machine direction only (MDO) and the film produced by biaxial drawing are the same as in Examples 13 - 15 and Example 17.The following are aspects of the present invention. [Aspect 1] A microporous polymer film, (a) one or more polypropylene copolymers that are 50 to 95 weight percent based on the total weight of the film, the polypropylene copolymer containing one or more polypropylene homopolymer chain segments and one or more ethylene-containing copolymer chain segments is included; the microporous polymer film has (i) a polypropylene homopolymer chain segment that is 50 to 82 weight percent based on the weight of the polypropylene copolymer, or 43 to 79 mole percent based on the molar content of the propylene polymerization units in the polypropylene homopolymer chain segment as a percentage of the total molar content of the polymerization monomer units in the polypropylene copolymer, a total amount of polypropylene homopolymer chain segments, and (ii) an ethylene-containing copolymer chain segment that is 18 to 50 weight percent based on the weight of the polypropylene copolymer, or 21 to 57 mole percent based on the molar content of the polymerization monomer units in the ethylene-containing copolymer chain segment as a percentage of the total molar content of the polymerization monomer units in the polypropylene copolymer, a total amount of ethylene-containing copolymer chain segments is included, and at least a portion of the ethylene-containing copolymer chain segment contains ethylene polymerization units in an amount of at least 45 weight percent based on the weight of the ethylene-containing copolymer chain segment, or at least 55 mole percent based on the molar content of the ethylene polymerization units in the ethylene-containing copolymer chain segment as a percentage of the total molar content of the polymerization monomer units in the ethylene-containing copolymer chain segment, one or more polypropylene copolymers, and (b) one or more ethylene-propylene elastomers that are 5 to 50 weight percent based on the total weight of the film, is included; A microporous polymer film in which at least 45 weight percent of the polymerization units in the ethylene-propylene elastomer are ethylene units. [Aspect 2] In (b), the one or more ethylene-propylene elastomers are 5 to 30 weight percent based on the total of (a) and (b) in the film, the microporous film according to aspect 1. [Aspect 3] In (b), the one or more ethylene-propylene elastomers are 5 to 20 weight percent based on the total of (a) and (b) in the film, the microporous film according to aspect 2. [Aspect 4] In (b), 45 to 80 weight percent of the polymerization units in the ethylene-propylene elastomer are ethylene units, the microporous film according to any one of aspects 1 to 3. [Aspect 5] In (b), 45 to 60 weight percent of the polymerization units in the ethylene-propylene elastomer are ethylene units, the microporous film according to aspect 4. [Aspect 6] In (b), the ethylene-propylene elastomer is ethylene-propylene rubber (EPR), ethylene propylene diene monomer (EPDM) rubber, or some mixture thereof, the microporous film according to any one of aspects 1 to 5. [Aspect 7] In (b), the ethylene-propylene elastomer has a Mooney viscosity of 10 to 40 Mu, the microporous film according to any one of aspects 1 to 6. [Aspect 8] The microporous film according to any one of aspects 1 to 7, comprising (a) and (b). [Aspect 9] The tensile modulus of the microporous polymer film comprising (a) and (b) is less than the tensile modulus of the film made of (a) only, the microporous film according to any one of aspects 1 to 8. [Aspect 10] The water vapor transmission rate of the microporous polymer film comprising (a) and (b) is less than the water vapor transmission rate of the film made of (a) only, the microporous film according to any one of aspects 1 to 9. [Aspect 11] In (a), the ethylene-containing copolymer chain segment is an ethylene-propylene copolymer chain segment, the microporous polymer film according to any one of aspects 1 to 10. [Aspect 12] In (a), the ethylene-propylene copolymer chain segment is an ethylene-propylene diblock copolymer chain segment containing a polypropylene block and a polyethylene block, or a diblock copolymer chain segment containing a polypropylene block and an ethylene-propylene copolymer block, the microporous polymer film according to aspect 11. [Aspect 13] The microporous polymer film according to any one of aspects 1 to 12, having 4 V / A, at least 25% porosity and a median pore diameter of at least 25 nm according to the UOP method 578-11, both characteristics being measured by mercury intrusion porosimetry. [Aspect 14] The microporous polymer film according to any one of aspects 1 to 13, wherein the non-porous polymer film has domains of (a) and (b), and the domain of (a) further has a morphology characterized by a plurality of polymer phases of polypropylene, a plurality of minority polymer domains of an ethylene-containing copolymer within the plurality of polymer phases, and inclusion phases of a major polypropylene phase within the plurality of minority polymer domains. [Aspect 15] The microporous polymer film according to any one of aspects 1 to 14, which is a roof film or a component thereof. [Aspect 16] The microporous polymer film according to any one of aspects 1 to 15, having a thickness of at least 100 μm to 2.5 mm. [Aspect 17] A medical packaging or active packaging article or a medical backtable cover comprising the microporous polymer film according to any one of aspects 1 to 16. [Aspect 18] The medical packaging or active packaging article or medical backtable cover according to aspect 17, wherein the microporous polymer film has a barrier against microorganisms that is less than 10% equivalent to the maximum intrusion, calculated %Pmax, as defined by ASTM F2638-18. [Aspect 19] The medical packaging or active packaging article or medical backtable cover according to aspect 17, wherein the microporous polymer film has a Gurley gauge air permeability of 1 to 35,000 seconds / 100 cm3 and controls the inflow or outflow of air or one or more gases into or out of the package. [Aspect 20] The medical packaging or active packaging article or medical backtable cover according to aspect 17, wherein the microporous polymer film is thermoformable and heat-sealable. [Aspect 21] A method of forming a microporous polymer film, the method steps being: A) Providing a mixture, wherein the mixture is (a) One or more polypropylene copolymers in an amount of 50 to 95 weight percent based on the total weight of the mixture, wherein: (i) One or more polypropylene homopolymer chain segments in an amount of 50 to 82 weight percent based on the weight of the polypropylene copolymer, or 43 to 79 mol percent based on the molar content of the propylene polymerization units in the polypropylene homopolymer chain segments as a percentage of the total molar content of the polymerization monomer units in the polypropylene copolymer, of one or more polypropylene homopolymer chain segments, and (ii) One or more ethylene-containing copolymer chain segments in an amount of 18 to 50 weight percent based on the weight of the polypropylene copolymer, or 21 to 57 mol percent based on the molar content of the polymerization monomer units in the ethylene-containing copolymer chain segments as a percentage of the total molar content of the polymerization monomer units in the polypropylene copolymer, of one or more ethylene-containing copolymer chain segments wherein at least a portion of the ethylene-containing copolymer chain segments contains polymerization units of ethylene in an amount of at least 45 weight percent based on the weight of the ethylene-containing copolymer chain segments, or at least 55 mol percent based on the molar content of the ethylene polymerization units in the ethylene-containing copolymer chain segments as a percentage of the total molar content of the polymerization monomer units in the ethylene-containing copolymer chain segments, one or more polypropylene copolymers, and (b) One or more ethylene-propylene elastomers in an amount of 5 to 50 weight percent based on the total weight of the mixture, a mixture; providing a mixture wherein at least 45 weight percent of the polymerization units in the ethylene-propylene elastomer are ethylene units; B) Forming a non-porous film from the mixture; and C) Subjecting the non-porous film to (i) At least one cold drawing step at a temperature in the range of -20°C to 50°C, and (ii) At least one hot drawing step at a temperature in the range of 50°C to 140°C subjected to successive cold drawing and hot drawing steps including a method including producing a microporous polymer film thereby. [Aspect 22] The method according to aspect 21, wherein in (b), 45 to 80 weight percent of the polymerized units in the ethylene-propylene elastomer are ethylene units. [Aspect 23] The method according to aspect 22, wherein in (b), 45 to 60 weight percent of the polymerized units in the ethylene-propylene elastomer are ethylene units. [Aspect 24] The method according to any one of aspects 21 to 23, wherein in (b), the ethylene-propylene elastomer is ethylene-propylene rubber (EPR), ethylene propylene diene monomer (EPDM) rubber, or a mixture of some of them. [Aspect 25] The method according to any one of aspects 21 to 24, wherein in (b), the ethylene-propylene elastomer has a Mooney viscosity of 10 to 40 Mu. [Aspect 26] The method according to any one of aspects 21 to 25, wherein the mixture consists of (a) and (b). [Aspect 27] The method according to any one of aspects 21 to 26, wherein in (a), the ethylene-containing copolymer chain segment is an ethylene-propylene copolymer chain segment. [Aspect 28] The method according to any one of aspects 21 to 27, wherein before forming the mixture with the one or more ethylene-propylene elastomers (b), the polypropylene copolymer of (a) is blended with the ethylene-containing copolymer of (a) to form a polymer blend. [Aspect 29] The method according to any one of aspects 21 to 28, wherein the at least one cold drawing step draws the film by at least 10% in at least one direction, and the at least one hot drawing step draws the film by at least 20% in at least one direction. [Aspect 30] The method according to any one of aspects 21 to 29, wherein the microporous polymer film has a porosity of at least 25% and a median pore diameter of at least 25 nm according to 4V / A, UOP method 578-11, and both characteristics are measured by mercury intrusion porosimetry. [Aspect 31] The method according to any one of aspects 21 to 30, wherein the microporous polymer film has a permeability in the range of 10 to 150 perm according to ASTM E96 / E96M-16.

Claims

1. A microporous polymer film comprising: (a) one or more polypropylene copolymers in an amount of 50 to 95 weight percent based on the total weight of the film, the polypropylene copolymer comprising one or more polypropylene homopolymer chain segments and one or more ethylene-containing copolymer chain segments ; wherein the polypropylene copolymer has: (i) a polypropylene homopolymer chain segment in an amount of 50 to 82 weight percent based on the weight of the polypropylene copolymer, or 43 to 79 mole percent as a percentage of the total molar content of the polymerized monomer units in the polypropylene copolymer, and (ii) an ethylene-containing copolymer chain segment in an amount of 18 to 50 weight percent based on the weight of the polypropylene copolymer, or 21 to 57 mole percent as a percentage of the total molar content of the polymerized monomer units in the polypropylene copolymer, with at least a portion of the ethylene-containing copolymer chain segment containing ethylene polymerized units in an amount of at least 45 weight percent based on the weight of the ethylene-containing copolymer chain segment, or at least 55 mole percent as a percentage of the total molar content of the polymerized monomer units of the ethylene-containing copolymer chain segment based on the molar content of the ethylene polymerized units in the ethylene-containing copolymer chain segment, and one or more polypropylene copolymers, (b) one or more ethylene-propylene elastomers in an amount of 5 to 50 weight percent based on the total weight of the film, ; A microporous polymer film wherein at least 45 weight percent of the polymerized units in the ethylene-propylene elastomer are ethylene units.

2. The microporous polymer film according to Claim 1, which is a roof film or a component thereof.

3. A medical packaging or active packaging article or a medical back table cover comprising the microporous polymer film according to Claim 1 or 2.

4. A method of forming a microporous polymer film, the method steps comprising: A) providing a mixture, the mixture comprising: (a) one or more polypropylene copolymers in an amount of 50 to 95 weight percent based on the total weight of the mixture: (i) one or more polypropylene homopolymer chain segments, which are 50 to 82% by weight based on the weight of the polypropylene copolymer, or 43 to 79 mol% as a percentage of the total molar content of the polymerized monomer units in the polypropylene copolymer; one or more polypropylene homopolymer chain segments; (ii) one or more ethylene-containing copolymer chain segments, which are 18 to 50% by weight based on the weight of the polypropylene copolymer, or 21 to 57 mol% as a percentage of the total molar content of the polymerized monomer units in the polypropylene copolymer; one or more ethylene-containing copolymer chain segments and at least a part of the ethylene-containing copolymer chain segments contains ethylene polymerized units in an amount of at least 45% by weight based on the weight of the ethylene-containing copolymer chain segments, or at least 55 mol% as a percentage of the total molar content of the polymerized monomer units of the ethylene-containing copolymer chain segments, based on the molar content of the ethylene polymerized units in the ethylene-containing copolymer chain segments; one or more polypropylene copolymers; (b) a mixture with 5 to 50 weight percent of one or more ethylene-propylene elastomers based on the total weight of the mixture; providing a mixture in which at least 45 weight percent of the polymerized units in the ethylene-propylene elastomer are ethylene units; B) forming a non-porous film from the mixture; and C) subjecting the non-porous film to (i) at least one cold drawing step at a temperature in the range of -20°C to 50°C, and (ii) at least one hot drawing step at a temperature in the range of 50°C to 140°C to a continuous cold drawing and hot drawing step including, thereby producing a microporous polymer film. A method.

Images