Low basis weight and high performance polyethylene-based sanitary base film

Abstract

The present invention relates to sanitary articles, such as diapers and sanitary napkins, with improved base films. Particularly, the polypropylene homopolymer is added into the core layer containing the polyethylene composition and the CaCO3 master batch, so that the performance of the bottom film in the hygienic product is improved.

Description

Technical Field

[0001] The present invention relates to hygienic products with improved base films, such as disposable baby and adult diapers and feminine care products, etc. In particular, the present invention improves the performance of the base film in hygienic products by adding a polypropylene homopolymer to a core layer comprising a polyethylene composition and a CaCO3 masterbatch (CaCO3 MB). Background Art

[0002] Hygiene products such as disposable baby and adult diapers, incontinence pads, and feminine care products such as sanitary napkins have important functions for different groups of people. Generally speaking, such hygiene products are usually made of a top sheet, an absorbent core, and a bottom film. The top sheet is the layer facing the skin and is liquid permeable, facilitating the entry of liquid exuded by the wearer into the hygiene product; the absorbent core is made of highly absorbent material to absorb liquid received through the top sheet; and the bottom film can be vapor permeable or vapor impermeable. If the bottom film is vapor permeable, the hygiene product is called a "breathable" product.

[0003] Breathable base films are commonly used in diapers, feminine care products and other hygiene products. They have high water vapor transmission capacity, but still maintain resistance to liquids (mainly water), thereby improving the comfort of the product. Currently, most breathable base films are manufactured by cast or blown extrusion processes, followed by machine direction orientation (MDO). Despite the use of cast or blown extrusion processes, most breathable base films are co-extruded in a single layer or three-layer configuration.

[0004] The main requirements for breathable bottom film are 5% and 10% yield in machine direction (MD), tensile strength at break in transverse direction (TD), MD trouser tear strength and water vapor transmission rate (WVTR). Under current conversion technology and formulation design, through different material selection, cast film ≥16 g / m2 (gsm) and blown film ≥14 g / m2 can meet most of the requirements of ordinary bottom film products.

[0005] However, it is still challenging to achieve high TD tensile strength and MD trouser tear strength for high-end products.

[0006] Furthermore, in recent years, the typical trend in base films has been to reduce the thickness of the base film, usually by making it from thinner films, to save material costs. However, the stiffness of the base film is very important to maintain the processability of the film, and as the film becomes thinner, the stiffness decreases. A common way to compensate for the loss of stiffness is to use a higher density polymer. However, the consequence of this is that the strength of the film will also decrease, and / or the end user may feel that the film is too stiff or too noisy to use, especially when softness is an important feature of hygiene products.

[0007] In particular, for base films produced by blow molding, it is very challenging for reduced film with a basis weight of 10-12 g / m2 to achieve comparable or even improved tensile properties as films with a basis weight of ≥14 g / m2.

[0008] Therefore, there is a need for improved base films for sanitary products that can achieve comparable or even improved tensile properties, toughness, water vapor transmission rate (WVTR) and / or processing properties compared to unreduced films on a reduced thickness basis.

[0009] The present invention achieves one or more of the above requirements. Summary of the invention

[0010] The inventors of the present invention unexpectedly found that by adding a polypropylene homopolymer (hPP) to an existing polyethylene-based core layer, a thinner and more stretchable breathable bottom film with improved water vapor transmission rate (WVTR) was successfully obtained. The polypropylene homopolymer of the present invention has a melt index of about 1-10 g / 10 min, preferably about 1-5 g / 10 min, measured under ASTM D1238 at 230°C and 2.16 kg; and has an isotactic index of about 95-99.9%, preferably about 96-99.9%, measured according to GB / T2412-2008.

[0011] The breathable base film of the present invention has a basis weight of about 10-12 g / m2. Compared with existing polyethylene-based base films with a basis weight of ≥14 g / m2, the base film of the present invention has comparable or even improved stretchability, toughness, water vapor transmission rate (WVTR) and / or processing performance, thereby providing significant cost savings for manufacturers and brand owners.

[0012] The inventors of the present invention unexpectedly discovered that the base film of the present invention has significantly improved TD stretch properties compared to base films whose core layer does not contain the polypropylene homopolymer described in the present invention, for example, the TD stretch properties are improved by greater than about 10%, greater than about 15%, greater than about 17%, and even greater than about 18%.

[0013] The inventors of the present invention unexpectedly discovered that the base film of the present invention has a significantly improved water vapor transmission rate (WVTR), such as an increase of greater than about 10%, an increase of greater than about 15%, or even an increase of greater than about 20%, compared to a base film that does not contain the polypropylene homopolymer of the present invention in the core layer.

[0014] In particular, the present invention relates to the following aspects.

[0015] According to one aspect of the present invention, the present invention relates to a base film for sanitary products, which comprises at least two surface layers and one core layer, in particular, the base film consists of two surface layers and one core layer, wherein each of the surface layers comprises a first polyethylene composition, a second polyethylene composition, and a CaCO3 masterbatch, and the core layer comprises a first polyethylene composition, a second polyethylene composition, a CaCO3 masterbatch and a polypropylene homopolymer,

[0016] wherein the polypropylene homopolymer has a melt index of 1-10 g / 10 min, preferably 1-5 g / 10 min, measured at 230° C. and 2.16 kg according to ASTM D1238; and an isotactic index of 95-99.9%, preferably 96-99.9%, measured according to GB / T2412-2008,

[0017] wherein the core layer comprises the CaCO3 masterbatch in an amount of about 60 wt%-80 wt%, comprises the polypropylene homopolymer in an amount of about 5 wt%-30 wt%, and the balance is the first polyethylene composition and the second polyethylene composition, based on the total weight of the core layer.

[0018] According to one aspect of the present invention, the core layer comprises the polypropylene homopolymer in an amount of about 5 wt%-30 wt%, or about 10 wt%-25 wt%, or about 10 wt%-20 wt%, or about 15 wt%-20 wt%, based on the total weight of the core layer.

[0019] According to one aspect of the present invention, the first polyethylene composition in the skin layer and the core layer has a density of 0.910 g / cm3-0.920 g / cm3 and a melt index I of 0.4-1.0 g / 10 min. 2.16 .

[0020] According to one aspect of the present invention, the second polyethylene composition in the skin layer and the core layer has a density of 0.920 g / cm3-0.935 g / cm3 and a melt index I of 1.0-2.0 g / 10 min. 2.16 .

[0021] According to one aspect of the present invention, the first polyethylene composition in the skin layer and the core layer has a melt index ratio MIR of 20.0-35.0, and a composition distribution breadth index CDBI of 20 wt % to less than 50 wt %.

[0022] According to one aspect of the present invention, the second polyethylene composition in the skin layer and the core layer has a melt index ratio MIR of 10.0-30.0, and a composition distribution breadth index CDBI of greater than 50 wt% to 80 wt%.

[0023] According to one aspect of the present invention, the CaCO3 masterbatch of the surface layer and the core layer is characterized in that the particle size range of CaCO3 is about 1.0-4.0 μm, preferably 1.2-2.4 μm, and more preferably 1.5-2.0 μm.

[0024] According to one aspect of the present invention, each of the surface layers comprises the first polyethylene composition and the second polyethylene composition in a total amount of about 20 wt%-40 wt%, and comprises the CaCO3 masterbatch in an amount of about 60 wt%-80 wt%, based on the total weight of the surface layer.

[0025] According to one aspect of the present invention, in each of the skin layers, the weight ratio of the first polyethylene composition to the second polyethylene composition is 3:1 to 1:3, preferably 2:1 to 1:1.

[0026] According to one aspect of the present invention, the first polyethylene composition and the second polyethylene composition of the skin layer and the core layer contain about 80.0 mol% to 99.9 mol% of units derived from ethylene and about 0.1 mol% to 20.0 mol% of units derived from C3-C10 alpha olefin comonomers, based on the total content of all monomers in the polyethylene composition.

[0027] According to one aspect of the present invention, each of the surface layers consists of the first polyethylene composition, the second polyethylene composition and the CaCO3 masterbatch.

[0028] According to one aspect of the present invention, the core layer is composed of the first polyethylene composition and the second polyethylene composition, the CaCO3 masterbatch and the polypropylene homopolymer.

[0029] According to one aspect of the present invention, the present invention relates to a base film for sanitary products, which consists of two surface layers and a core layer, wherein each of the surface layers consists of a first polyethylene composition, a second polyethylene composition and a CaCO3 masterbatch, and the core layer consists of a first polyethylene composition, a second polyethylene composition, a CaCO3 masterbatch and a polypropylene homopolymer.

[0030] wherein the polypropylene homopolymer has a melt index of 3.2 g / 10 min, measured at 230° C. and 2.16 kg according to ASTM D1238; and an isotactic index of 97.2%, measured according to GB / T2412-2008,

[0031] wherein the core layer comprises the CaCO3 masterbatch in an amount of about 60 wt% to 80 wt%, comprises the polypropylene homopolymer in an amount of about 5 wt% to 30 wt%, and the balance is the first polyethylene composition and the second polyethylene composition, based on the total weight of the core layer,

[0032] wherein the CaCO3 masterbatch has a CaCO3 particle size of about 2.0 μm,

[0033] The first polyethylene composition has a density of about 0.918 g / cm3, a melt index of about 0.50 g / 10 min measured according to ASTM D1238 (190°C / 2.16 kg), a melt index ratio (MIR) of about 29.5, and a melt index ratio (MIR) of about 1.5. 21.6 / I 2.16 ) and a composition distribution breadth index CDBI of about 36.1 wt %, and

[0034] The second polyethylene composition has a density of about 0.927 g / cm3, a melt index of about 1.3 g / 10 min measured according to ASTM D1238 (190°C / 2.16 kg), a melt index ratio MIR (I 21.6 / I 2.16 ) and a composition distribution breadth index CDBI of about 59.4 wt%.

[0035] According to one aspect of the present invention, the present invention relates to a base film for sanitary products, which consists of two surface layers and a core layer, wherein each of the surface layers consists of a first polyethylene composition, a second polyethylene composition and a CaCO3 masterbatch, and the core layer consists of a first polyethylene composition, a second polyethylene composition, a CaCO3 masterbatch and a polypropylene homopolymer.

[0036] wherein the polypropylene homopolymer has a melt index of 3.2 g / 10 min, measured at 230° C. and 2.16 kg according to ASTM D1238; and an isotactic index of 97.2%, measured according to GB / T2412-2008,

[0037] wherein the core layer comprises the CaCO3 masterbatch in an amount of about 60 wt% to 80 wt%, comprises the polypropylene homopolymer in an amount of about 5 wt% to 30 wt%, and the balance is the first polyethylene composition and the second polyethylene composition, based on the total weight of the core layer,

[0038] wherein each of the skin layers comprises the first polyethylene composition and the second polyethylene composition in a total amount of about 20 wt% to 40 wt%, and comprises the CaCO3 masterbatch in an amount of about 60 wt% to 80 wt%, based on the total weight of the skin layer,

[0039] wherein the CaCO3 masterbatch has a CaCO3 particle size of about 2.0 μm,

[0040] The first polyethylene composition has a density of about 0.918 g / cm3, a melt index of about 0.50 g / 10 min measured according to ASTM D1238 (190°C / 2.16 kg), a melt index ratio (MIR) of about 29.5, and a melt index ratio (MIR) of about 1.5. 21.6 / I 2.16 ) and a composition distribution breadth index CDBI of about 36.1 wt %, and

[0041] The second polyethylene composition has a density of about 0.927 g / cm3, a melt index of about 1.3 g / 10 min measured according to ASTM D1238 (190°C / 2.16 kg), a melt index ratio MIR (I 21.6 / I 2.16 ) and a composition distribution breadth index CDBI of about 59.4 wt%.

[0042] According to one aspect of the present invention, the first polyethylene composition is EXCEED TM XP 8358ML polyethylene composition.

[0043] According to one aspect of the present invention, the second polyethylene composition is EXCEED TM 1327MA polyethylene composition.

[0044] According to one aspect of the present invention, the CaCO3 masterbatch is from Imerys

[0045] According to one aspect of the present invention, the polypropylene homopolymer is T30S from Maoming Petrochemical, ie, "PP PPH-T03 (T30S) Sinopec / Drawing Grade" polypropylene homopolymer.

[0046] According to one aspect of the present invention, the present invention relates to a hygienic product comprising the base film of the present invention, wherein the hygienic product is selected from disposable baby and adult diapers, incontinence pads, feminine care products and combinations thereof.

[0047] According to one aspect of the present invention, the present invention relates to a method for preparing the base film for sanitary products of the present invention, which comprises blow molding coextrusion of the layers of the base film and performing machine direction orientation (MDO).

[0048] According to one aspect of the present invention, the present invention relates to the use of a polypropylene homopolymer in a base film for sanitary products comprising a first polyethylene composition, a second polyethylene composition and a CaCO3 masterbatch for improving the tensile properties of the base film, wherein the polypropylene homopolymer has a melt index of 1-10, preferably 1-5, measured under conditions of 230°C and 2.16kg according to ASTM D1238; and has an isotactic index of 95-99.9%, measured according to GB / T2412-2008.

[0049] According to one aspect of the present invention, the present invention relates to the use of a polypropylene homopolymer in a base film for sanitary products comprising a first polyethylene composition, a second polyethylene composition and a CaCO3 masterbatch for reducing the basis weight of the base film, wherein the polypropylene homopolymer has a melt index of 1-10, preferably 1-5, which is measured under the conditions of 230°C and 2.16kg according to ASTM D1238; and has an isotactic index of 95-99.9%, which is measured according to GB / T2412-2008.

[0050] Hygiene products for different groups of people include disposable baby and adult diapers, incontinence pads, feminine care products, etc. Generally speaking, such hygiene products are usually made of a top sheet, an absorbent core and a bottom film.

[0051] Top sheet

[0052] The topsheet is usually the layer of the sanitary product that faces the wearer's body and contacts it, and is therefore the first layer to receive body secretions. The topsheet is usually made of a single layer, but it can also contain more than 1 layer (for example, a central topsheet layer and two overlapping side strips). For example, a single nonwoven material can be used, but the topsheet can be composed of multiple layers and treated to be hydrophilic so that liquids can pass through.

[0053] The topsheet is generally liquid permeable, ie, permits liquids to pass through the topsheet without significantly impeding the passage of liquids.

[0054] Any conventional top sheet material can be used.For example, nonwoven material or porous polyolefin film can be used to make suitable top sheet.An exemplary top sheet is a relatively hydrophobic 20 grams per square meter spunbond nonwoven web, which comprises the bicomponent fibers (such as polypropylene / polyethylene polymer) of the sleeve / core type.If desired, the top sheet can be processed with a surfactant to enhance the penetration of liquid to the absorbent cores.The surfactant can be nonionic, and should be non-irritating to the skin.The top sheet can have a plurality of holes so that the liquid deposited thereon can pass through faster to reach the absorbent cores.

[0055] Absorbent core

[0056] Hygiene products also include an absorbent core disposed between the top sheet and the bottom film. As used herein, the term "absorbent core" refers to a material or combination of materials that is suitable for absorbing, retaining, distributing and / or storing liquids (e.g., urine, blood, menses and / or other exudates).

[0057] The size and shape of the absorbent core can make the surface of the absorbent core on the horizontal plane significantly smaller than the surface of the top sheet. So-called "significantly smaller than" means that the surface of the absorbent core is at least about 10% smaller than the top sheet surface, or at least about 25% smaller than the top sheet surface. The absorbent core can generally be located in the middle of the article. The absorbent core can be arranged away from the periphery of the article to provide improved flexibility along the edge of the article.

[0058] By providing an absorbent core having a surface that is significantly smaller than the topsheet, a variety of benefits can be achieved. The amount of absorbent core material used is reduced, reducing the overall manufacturing cost of the product. An absorbent core with a smaller surface can also increase the overall flexibility of the article, because areas of the article without the absorbent core are generally less rigid than areas with the absorbent core.

[0059] The absorbent core can be made into a variety of shapes, such as round, oval, rectangular and square. For example, for ease of manufacturing, the absorbent core is usually rectangular. However, if the shape of the absorbent core is an arc (such as an oval) without right angles, its flexibility and compatibility with various underwear styles will be better.

[0060] The absorbent core may be made of any suitable material. Non-limiting examples of suitable liquid-absorbing materials include comminuted wood pulp (commonly referred to as airfelt); wrinkled cellulose flocs; absorbent gelling materials, including superabsorbent polymers, such as hydrogel-forming polymeric gelling agents; chemically hardened, modified or cross-linked cellulose fibers; meltblown polymers, including co-form polymers; synthetic fibers, including crimped polyester fibers; tissues, including tissue wraps and tissue laminates; capillary channel fibers; absorbent foams; absorbent sponges; synthetic staple fibers; peat moss; foamed polyethylene or polypropylene compositions; nonwoven polyethylene or polypropylene materials; or any equivalent materials; or combinations thereof. For example, the absorbent core may include a superabsorbent polymer (SAP) typically distributed in a matrix of cellulose fibers to reduce the thickness of the absorbent core.

[0061] The absorbent core can be a single layer, or a laminate of two or more layers. For example, the absorbent core can include a fluid-impermeable barrier layer on its side facing the base film to prevent the fluid trapped by the absorbent core from passing through the sanitary product. General information about the absorbent core can be found in WO 2002 / 007662 and WO 1991 / 019471.

[0062] Base film

[0063] The general function of base film is to prevent the excrement absorbed by the absorbent core from escaping from the sanitary product. Base film can include any suitable material. In general, these materials are usually flexible, liquid-resistant and impermeable to liquid. Base film can be a single layer, or two or more layers. Base film can be a cast film or a blown film, optionally, can also be an embossed film and / or along any direction: longitudinal (MD) or transverse (TD), online or offline oriented film or a stretch film. Base film can also be coextruded. Base film can also contain filler, pigment, various additives and any combination thereof. Base film can also be a laminate with nonwoven fabric.

[0064] Typically, a thinner base film is desired to save material costs and for design considerations of the final product. For example, the average base film thickness of the base film may be 50 microns or less, 45 microns or less, 40 microns or less, 35 microns or less, 30 microns or less, 25 microns or less, 20 microns or less. As used herein, "average base film thickness" refers to the thickness of the film, usually expressed in microns, before any additional conversion or processing (such as embossing) is performed. Because it is difficult to measure the thickness of an embossed film, the thickness of an embossed film may be expressed in grams per square meter or gsm, which is equal to the weight of 1 square meter of film.

[0065] Under the current conversion technology and formulation design, through different material selection, cast film ≥16 g / m2 (gsm) and blown film ≥14 g / m2 can meet most of the requirements of ordinary bottom film products.

[0066] The inventors of the present invention have surprisingly found that by adding a polypropylene homopolymer (hPP) to an existing polyethylene-based core layer, a thinner and more stretchable breathable backsheet film with improved water vapor transmission rate (WVTR) is successfully obtained.

[0067] The breathable base film of the present invention has a basis weight of 10-12 g / m2. Compared with existing polyethylene-based base films with a basis weight of ≥14 g / m2, the base film of the present invention has comparable or even improved stretchability, toughness, water vapor transmission rate (WVTR) and / or processing performance, thereby providing significant cost savings for manufacturers and brand owners.

[0068] Hygiene products are divided into "breathable" hygiene products and ordinary hygiene products. Breathable hygiene products tend to receive a higher premium in the market. Therefore, vapor-permeable base films are called breathable base films and are used in breathable hygiene products. These breathable base films can make clothing cooler and allow the products to maintain a certain degree of dryness when worn. Generally speaking, these breathable base films allow vapor to pass through, usually expressed by water vapor transmission rate (WVTR), while preventing liquids from passing through.

[0069] A breathable base film can be obtained by forming microcavities in one or more layers of the base film. The microcavities can be formed by adding fillers, such as calcium carbonate (CaCO3) or other suitable materials, to one or more layers of the base film and then orienting or stretching them. Other suitable materials include organic fillers, such as polystyrene in polyethylene, or water-swellable fillers, such as silica or hydrogels.

[0070] The base film has a clothing-facing side and an opposite side facing the body. The clothing-facing side of the base film may include a non-adhesive region and an adhesive region. The adhesive region may be provided by any conventional method. Pressure-sensitive adhesives are generally considered to be well suited for achieving this purpose.

[0071] As mentioned above, the base film for sanitary products of the present invention comprises at least two surface layers and one core layer. In particular, the base film for sanitary products of the present invention consists of two surface layers and one core layer.

[0072] The thickness ratio between the layers is not particularly limited, and can be selected conventionally in the art as long as it does not impair the beneficial effects of the present invention. For example, the thickness ratio of the surface layer / core layer / surface layer can be 1:2:1.

[0073] According to the base film for sanitary products of the present invention, each of the surface layers comprises a first polyethylene composition, a second polyethylene composition and a CaCO3 masterbatch, and the core layer comprises a first polyethylene composition, a second polyethylene composition, a CaCO3 masterbatch and a polypropylene homopolymer.

[0074] Polyethylene composition

[0075] First polyethylene composition

[0076] As described herein, the first polyethylene composition for the base film of the present invention can include about 80.0 mol % to about 99.9 mol % of units derived from ethylene. The lower limit of the ethylene content range can be 80.0 mol %, 85.0 mol %, 90.0 mol %, 92.0 mol %, 94.0 mol %, 95.0 mol %, 96.0 mol %, 97.0 mol %, 98.0 mol % or 99.0 mol %, based on polymer units derived from ethylene. The upper limit of the ethylene content range of the polyethylene composition can be 80.0 mol %, 85.0 mol %, 90.0 mol %, 92.0 mol %, 94.0 mol %, 95.0 mol %, 96.0 mol %, 97.0 mol %, 98.0 mol %, 99.0 mol %, 99.5 mol % or 99.9 mol %, based on polymer units derived from ethylene.

[0077] In addition, the first polyethylene composition can be prepared by polymerization of ethylene with an alpha-olefin comonomer having 3 to 10 carbon atoms. The alpha-olefin comonomer is selected from monomers having 3 to 10 carbon atoms, such as C3-C10 alpha-olefins or C4-C8 alpha-olefins. The alpha-olefin comonomer can be linear or branched, and can also include two unsaturated carbon-carbon bonds, i.e., dienes. Suitable comonomers include linear C3-C10 alpha-olefins and alpha-olefins having one or more C1-C3 alkyl branches or aromatic groups. Examples of monomers include propylene, 1-butene, 3-methyl-1-butene, 3,3-dimethyl-1-butene, 1-pentene, 1-pentene having one or more methyl, ethyl or propyl substituents, 1-hexene having one or more methyl, ethyl or propyl substituents, 1-heptene, 1-octene, 1-octene having one or more methyl, ethyl or propyl substituents, 1-octene having one or more methyl, ethyl or propyl substituents, 1-nonene having one or more methyl, ethyl or propyl substituents, 1-nonene having one or more methyl, ethyl or propyl substituents, ethyl, methyl or dimethyl substituted 1-decene, 1-dodecene and styrene.

[0078] Example combinations of ethylene and comonomers include ethylene / 1-butene, ethylene / 1-pentene, ethylene / 4-methyl-1-pentene, ethylene / 1-hexene, ethylene / 1-octene, ethylene / decene, ethylene / dodecene, ethylene / 1-butene / 1-hexene, ethylene / 1-butene / 1-pentene, ethylene / 1-butene / 4-methyl-1-pentene, ethylene / 1-butene / 1-octene, ethylene / 1-hexene / 1-pentene, ethylene / 1-hex ... The comonomers of the present invention are ethylene / 1-octene / 1-pentene, ethylene / 1-octene / 4-methyl-1-pentene, ethylene / 1-hexene / 1-octene, ethylene / 1-hexene / decene, ethylene / 1-hexene / dodecene, ethylene / 1-propylene / 1-octene, ethylene / 1-octene / 1-butene, ethylene / 1-octene / 1-pentene, ethylene / 1-octene / 4-methyl-1-pentene, ethylene / 1-octene / 1-hexene, ethylene / 1-octene-decene, ethylene / 1-octene / dodecene and combinations thereof. It should be understood that the above-listed comonomers and comonomer combinations are exemplary only and are not restrictive. Typically, the comonomer is 1-butene, 1-hexene or 1-octene.

[0079] In the copolymerization process, the monomer feed is adjusted to provide a ratio of ethylene to a comonomer (such as an alpha-olefin) to obtain a polyethylene having a comonomer content of about 0.1 mol % to about 20 mol %. In other aspects, the comonomer content is about 0.1 mol % to about 4.0 mol %, or about 0.1 mol % to about 3.0 mol %, or about 0.1 mol % to about 2.0 mol %, or about 0.5 mol % to about 5.0 mol %, or about 1.0 mol % to about 5.0 mol %, and the comonomer content is based on the total content of all monomers in the first polyethylene composition.

[0080] The density of the first polyethylene composition can have a range of about 0.910 g / cm3 to about 0.945 g / cm3, preferably about 0.912 g / cm3 to about 0.925 g / cm3, preferably about 0.910 g / cm3 to about 0.920 g / cm3, preferably about 0.915 g / cm3 to about 0.921 g / cm3, preferably about 0.910 g / cm3 to about 0.918 g / cm3, preferably about 0.912 g / cm3 to about 0.918 g / cm3, measured according to ASTM D792. These ranges include, but are not limited to, the range formed by the combination of any of the above numerical values.

[0081] Preferably, the density of the first polyethylene composition may have a range of about 0.910 g / cm3 to about 0.920 g / cm3, preferably about 0.912 g / cm3 to about 0.918 g / cm3.

[0082] According to ASTM D1238 (190°C / 2.16kg), the first polyethylene composition has the following melt index MI (I 2.16 ) (in grams per 10 minutes (g / 10min)) range: about 0.1-about 300g / 10min, or about 0.1-about 100g / 10min, or about 0.1-about 50g / 10min, or about 0.1-about 5.0g / 10min, or about 0.1-about 3.0g / 10min, or about 0.1-about 2.0g / 10min, or about 0.1-about 1.2g / 10min, or about 0.2-about 1.5g / 10min, or about 0.2-about 1.1g / 10min, or about 0.3-about 1.0g / 10min, or about 0.4-about 1.0g / 10min, or about 0.4-about 0.8g / 10min. These ranges include, but are not limited to, the range formed by the combination of any of the above numerical values.

[0083] Preferably, the first polyethylene composition has a melt index MI (MI) of about 0.4 to about 1.0 g / 10 min, or about 0.4 to about 0.8 g / 10 min. 2.16 ).

[0084] The first polyethylene composition can have a melt index ratio ("MIR"), which is a dimensionless number that is the ratio of the high loading MI to the low loading MI, or I 21.6 / I 2.16, measured according to ASTM D1238. The MIR of the first polyethylene composition herein is from about 10.0 to about 50.0, or from about 15.0 to about 45.0, or from about 20.0 to about 40.0, or from about 20.0 to about 35.0, or from about 22 to about 38, or from about 20 to about 32, or from about 25 to about 32, or from about 28 to about 30.

[0085] Preferably, the first polyethylene composition has an MIR of about 20.0 to about 35.0, or about 22 to about 38, or about 20 to about 32, or about 25 to about 32, or about 28 to about 30.

[0086] EXCEED is used in the embodiment of the present invention TM XP 8358ML is used as the first polyethylene composition, which has an MIR (I 21.6 / I 2.16 ).

[0087] The first polyethylene composition can have a high load melt index ("HLMI"), also referred to herein as I 21.6 , measured according to ASTM D1238, Condition F (190°C / 21.6 kg). Any given polymer composition has an MI and MIR. Therefore, the HLMI is fixed and can be calculated if the MI and MIR are known.

[0088] The term "Composition Distribution Breadth Index (CDBI)" represents the weight percent of copolymer molecules having a comonomer content within 50% of the median molar content of all comonomers. The first polyethylene composition of the present invention generally has a broad composition distribution as measured by the Composition Distribution Breadth Index (CDBI).

[0089] The CDBI of a copolymer can be measured using techniques known in the art. The CDBI of a copolymer is readily determined using well-known techniques for isolating individual fractions of a copolymer sample. One such technique is temperature rising elution fractionation (TREF), as described in Wild et al., J. Poly. Sci., Poly. Phys. Ed., Vol. 20, pp. 441-455 (1982), which is incorporated herein by reference.

[0090] Details on determining the CDBI of a copolymer are known to those skilled in the art, see, for example, PCT Patent Application WO 1993 / 003093 published on February 18, 1993, regarding CDBI.

[0091] The first polyethylene composition can have a composition distribution breadth index (CDBI) of less than about 50 wt%, or less than about 40 wt%, or less than about 30 wt%.

[0092] Preferably, the first polyethylene composition has a composition distribution breadth index (CDBI) of from about 20 wt% to about less than 50 wt%.

[0093] EXCEED is used in the embodiment of the present invention TM XP 8358ML was used as the first polyethylene composition, which had a CDBI of about 36.1 wt%.

[0094] Second polyethylene composition

[0095] As described herein, the second polyethylene composition for base film of the present invention can include about 80.0 mole % to about 99.9 mole % of units derived from ethylene. The lower limit of the ethylene content range can be 80.0 mole %, 85.0 mole %, 90.0 mole %, 92.0 mole %, 94.0 mole %, 95.0 mole %, 96.0 mole %, 97.0 mole %, 98.0 mole % or 99.0 mole %, based on polymer units derived from ethylene. The ethylene content range upper limit of the polyethylene composition can be 80.0 mole %, 85.0 mole %, 90.0 mole %, 92.0 mole %, 94.0 mole %, 95.0 mole %, 96.0 mole %, 97.0 mole %, 98.0 mole %, 99.0 mole %, 99.5 mole % or 99.9 mole %, based on polymer units derived from ethylene.

[0096] In addition, the second polyethylene composition can be prepared by polymerization of ethylene with an alpha-olefin comonomer having 3 to 10 carbon atoms. The alpha-olefin comonomer is selected from monomers having 3 to 10 carbon atoms, such as C3-C10 alpha-olefins or C4-C8 alpha-olefins. The alpha-olefin comonomer can be linear or branched, and can also include two unsaturated carbon-carbon bonds, i.e., dienes. Suitable comonomers include linear C3-C10 alpha-olefins and alpha-olefins having one or more C1-C3 alkyl branches or aromatic groups. Examples of monomers include propylene, 1-butene, 3-methyl-1-butene, 3,3-dimethyl-1-butene, 1-pentene, 1-pentene having one or more methyl, ethyl or propyl substituents, 1-hexene having one or more methyl, ethyl or propyl substituents, 1-heptene, 1-octene, 1-octene having one or more methyl, ethyl or propyl substituents, 1-octene having one or more methyl, ethyl or propyl substituents, 1-nonene having one or more methyl, ethyl or propyl substituents, 1-nonene having one or more methyl, ethyl or propyl substituents, ethyl, methyl or dimethyl substituted 1-decene, 1-dodecene and styrene.

[0097] Example combinations of ethylene and comonomers include ethylene / 1-butene, ethylene / 1-pentene, ethylene / 4-methyl-1-pentene, ethylene / 1-hexene, ethylene / 1-octene, ethylene / decene, ethylene / dodecene, ethylene / 1-butene / 1-hexene, ethylene / 1-butene / 1-pentene, ethylene / 1-butene / 4-methyl-1-pentene, ethylene / 1-butene / 1-octene, ethylene / 1-hexene / 1-pentene, ethylene / 1-hex ... The comonomers of the present invention are ethylene / 1-octene / 1-pentene, ethylene / 1-octene / 4-methyl-1-pentene, ethylene / 1-hexene / 1-octene, ethylene / 1-hexene / decene, ethylene / 1-hexene / dodecene, ethylene / 1-propylene / 1-octene, ethylene / 1-octene / 1-butene, ethylene / 1-octene / 1-pentene, ethylene / 1-octene / 4-methyl-1-pentene, ethylene / 1-octene / 1-hexene, ethylene / 1-octene-decene, ethylene / 1-octene / dodecene and combinations thereof. It should be understood that the above-listed comonomers and comonomer combinations are exemplary only and are not restrictive. Typically, the comonomer is 1-butene, 1-hexene or 1-octene.

[0098] In the copolymerization process, the monomer feed is adjusted to provide a ratio of ethylene to a comonomer (such as an alpha-olefin) to obtain a polyethylene having a comonomer content of about 0.1 mol % to about 20 mol %. In other aspects, the comonomer content is about 0.1 mol % to about 4.0 mol %, or about 0.1 mol % to about 3.0 mol %, or about 0.1 mol % to about 2.0 mol %, or about 0.5 mol % to about 5.0 mol %, or about 1.0 mol % to about 5.0 mol %, and the comonomer content is based on the total content of all monomers in the second polyethylene composition.

[0099] The density of the second polyethylene composition can have a range of about 0.910 g / cm3 to about 0.945 g / cm3, preferably about 0.920 g / cm3 to about 0.935 g / cm3, preferably about 0.925 g / cm3 to about 0.930 g / cm3, measured according to ASTM D792. These ranges include, but are not limited to, the range formed by the combination of any of the above numerical values.

[0100] Preferably, the density of the second polyethylene composition may have a range of about 0.920 g / cm3 to about 0.935 g / cm3, preferably about 0.925 g / cm3 to about 0.930 g / cm3.

[0101] According to ASTM D1238 (190°C / 2.16kg), the second polyethylene composition has the following melt index MI (I 2.16) (in grams per 10 minutes (g / 10min)) range: about 0.1-about 300g / 10min, or about 0.1-about 100g / 10min, or about 0.1-about 50g / 10min, or about 0.1-about 5.0g / 10min, or about 0.1-about 3.0g / 10min, or about 0.1-about 2.0g / 10min, or about 0.5-about 2.0g / 10min, or about 1.0-about 2.0g / 10min, or about 1.0-about 1.5g / 10min. These ranges include, but are not limited to, the range formed by the combination of any of the above numerical values.

[0102] Preferably, the second polyethylene composition has a melt index MI (MI) of about 0.5 to about 2.0 g / 10 min, or about 1.0 to about 2.0 g / 10 min, or about 1.0 to about 1.5 g / 10 min. 2.16 ).

[0103] The second polyethylene composition can have a melt index ratio ("MIR"), which is a dimensionless number that is the ratio of the high loading MI to the low loading MI, or I 21.6 / I 2.16 , measured according to ASTM D 1238. The MIR of the second polyethylene composition herein is from about 10.0 to about 30.0, preferably from about 15.0 to about 20.0.

[0104] EXCEED is used in the embodiment of the present invention TM 1327MA as the second polyethylene composition, which has an MIR (I 21.6 / I 2.16 ).

[0105] The second polyethylene composition can have a high load melt index ("HLMI"), also referred to herein as I 21.6 , measured according to ASTM D1238, Condition F (190°C / 21.6 kg). Any given polymer composition has an MI and MIR. Therefore, the HLMI is fixed and can be calculated if the MI and MIR are known.

[0106] The term "composition distribution breadth index (CDBI)" represents the weight percentage of copolymer molecules having a comonomer content within 50% of the median molar content of all comonomers. The second polyethylene composition of the present invention generally has a broad composition distribution as measured by the composition distribution breadth index (CDBI). The CDBI of a copolymer can be measured using techniques known in the art.

[0107] The CDBI of a copolymer is readily determined using well-known techniques for isolating individual fractions of a copolymer sample. One such technique is temperature rising elution fractionation (TREF), as described in Wild et al., J. Poly. Sci., Poly. Phys. Ed., Vol. 20, pp. 441-455 (1982), which is incorporated herein by reference.

[0108] Details on determining the CDBI of a copolymer are known to those skilled in the art, see, for example, PCT Patent Application WO 1993 / 003093 published on February 18, 1993, regarding CDBI.

[0109] The second polyethylene composition may have a composition distribution breadth index (CDBI) greater than 40 wt%, or greater than 50 wt%, or greater than 60 wt%, or greater than 70 wt%.

[0110] Preferably, the second polyethylene composition may have a composition distribution breadth index (CDBI) greater than 50 wt%, preferably greater than 50 wt% to 80 wt%.

[0111] EXCEED is used in the embodiment of the present invention TM 1327MA was used as the second polyethylene composition, which had a composition distribution breadth index (CDBI) of about 59.4 wt%.

[0112] Certain polyethylene compositions are currently used as EXCEED TM XP metallocene polyethylene ("mPE") is commercially available from ExxonMobil Chemical Company in Houston, Texas, USA. TM XP metallocene polyethylene provides excellent properties such as dart impact strength, flex cracking resistance and machine direction ("MD") tear, while maintaining stiffness at lower density. EXCEED TM XP metallocene polyethylene can provide optimized solutions with a good balance between melt strength, toughness, stiffness and sealing properties, which makes this series of polymers very suitable for blown film / sheet solutions.

[0113] More specifically, EXCEED TM XP 8358ML polyethylene composition is an ethylene / 1-hexene copolymer from ExxonMobil Chemical Company, Houston, Texas, U.S.A. This polyethylene composition has excellent toughness, high flex crack resistance and increased discharge rate, as well as excellent bubble stability, suitable for a variety of film applications. TMXP8358 has a density of 0.918 g / cm3, a melt index of 0.50 g / 10 min, and a MIR (I 21.6 / I 2.16 ) is about 29.5 and CDBI is about 36.1 wt %.

[0114] More specifically, EXCEED TM The 1327MA polyethylene composition is an ethylene / 1-hexene copolymer from ExxonMobil Chemical Company, Houston, Texas, USA. TM The density of 1327MA is 0.927 g / cm3, the melt index is 1.3 g / 10 min, according to ASTM D1238 (190°C / 2.16 kg), and MIR (I 21.6 / I 2.16 ) is about 15.9 and CDBI is about 59.4 wt%.

[0115] Currently, some polyethylene compositions are The metallocene polyethylene compositions sold under the trade name Metallocene polyethylene compositions offer a balance between processability and mechanical properties, including tensile strength and elongation at break, while also offering high tensile strength and elongation at break, as well as longer pipe rupture (failure) time and toughness. Applications for ENABLE products include food packaging, form-fill-and-seal packaging, heavy-duty bags, laminated films, stand-up pouches, multilayer packaging films and shrink films.

[0116] For example, ENABLE TM 20-05 polyethylene composition is an ethylene / 1-hexene copolymer designed for blown film, including formulated and unformulated types. ENABLE TM The 20-05 polymer has a density of 0.920 g / cm3 and a melt index of 0.5 g / 10 min.

[0117] Used to create EXCEED TM and ENABLE TMMaterials and processes for polyethylene compositions have been described in Example 1 of U.S. Patent No. 6,956,088. Other publications describing materials and processes include U.S. Patent Application Publication No. 2009 / 0297810, Example 1; U.S. Patent Application Publication No. 2015 / 0291748, particularly PE1-PE5 in the Examples; and WO 2014 / 099356, particularly PE3 mentioned on page 12 and in the Examples, including the use of, for example, the silica-supported hafnium transition metallocene / methylaluminoxane catalyst system described in U.S. Patent Nos. 6,242,545 and 6,248,845, particularly Example 1.

[0118] CaCO3 Masterbatch

[0119] The CaCO3 masterbatch used in the surface layer and the core layer of the base film of the present invention is characterized in that the particle size range of CaCO3 is about 1.0-4.0 μm, preferably 1.2-2.4 μm, and more preferably 1.5-2.0 μm.

[0120] The CaCO3 masterbatch used in the surface layer and the core layer of the base film of the present invention is suitable for the blow molding process and is suitable for the breathable base film of sanitary products.

[0121] Typically, commercially available CaCO3 masterbatches suitable for blow molding processes and for breathable base films for sanitary products contain a majority of CaCO3 particles, a small portion of polyethylene (for example, including linear low-density polyethylene and low-density polyethylene) and a small amount of filler (in some cases, the filler content can be ignored).

[0122] For example, the CaCO3 masterbatch may contain about 40 wt%-90 wt% CaCO3 and about 10 wt%-60 wt% polyethylene and a small amount of filler.

[0123] Preferably, the CaCO3 masterbatch may contain about 50 wt%-80 wt% CaCO3 and about 20 wt%-50 wt% polyethylene and a small amount of filler.

[0124] For example, the CaCO3 masterbatch may contain about 70 wt% CaCO3 and about 30 wt% polyethylene and a small amount of filler.

[0125] The CaCO3 masterbatch used in the present invention is commercially available, including AT-N70-NC001 from Kingfa Sci.&Tech.Co., Ltd., and

[0126] AT-N70-NC001 contains about 70 wt% CaCO3 and about 30 wt% polyethylene.

[0127] With a CaCO3 particle size of 1.2 μm, The CaCO3 particle size is 2.0 μm.

[0128] Polypropylene homopolymer

[0129] The polypropylene homopolymer used in the core layer of the base film of the present invention is characterized in that the polypropylene homopolymer has a melt index of 1-10 g / 10 min, preferably 1-5 g / 10 min, which is measured under the conditions of 230° C. and 2.16 kg according to ASTM D1238; and has an isotactic index of 95-99.9%, preferably 96-99.9%, which is measured according to GB / T2412-2008.

[0130] The polypropylene homopolymer used in the core layer of the base film of the present invention is suitable for a blow molding process and is suitable for a breathable base film for sanitary products.

[0131] The polypropylene homopolymer used in the present invention can be commercially obtained, including T30S from Maoming Petrochemical, that is, "PP PPH-T03 (T30S) Sinopec / Drawing Grade" polypropylene homopolymer.

[0132] The polypropylene homopolymer of "PP PPH-T03 (T30S) Sinopec / Drawing Grade" has the following performance parameters:

[0133] Melt index: 3.2 g / 10 min, measured at 230 ° C and 2.16 kg;

[0134] Isotactic index: 97.2%;

[0135] Ash content: 0.02%;

[0136] Tensile break nominal strain: 498%;

[0137] Tensile yield strength: 31.5MPa.

[0138] Method for manufacturing base film

[0139] The base film for hygienic products of the present invention can be manufactured by blown coextrusion conventionally used in the art, followed by machine direction orientation (MDO) treatment. DETAILED DESCRIPTION

[0140] The test methods used in the present invention are summarized in the following table.

[0141]

[0142] Material

[0143] Polypropylene homopolymer: T30S from Maoming Petrochemical, i.e., "PP PPH-T03 (T30S) Sinopec / Drawing Grade" polypropylene homopolymer:

[0144] Melt index: 3.2 g / 10 min, measured at 230 ° C and 2.16 kg;

[0145] Isotactic index: 97.2%.

[0146] Polyethylene composition:

[0147] The first polyethylene composition is EXCEED TM XP 8358ML polyethylene composition, an ethylene / 1-hexene copolymer, from ExxonMobil Chemical Company, Houston, Texas, USA. EXCEED TM XP 8358ML has a density of 0.918 g / cm3, a melt index of 0.50 g / 10 min, and a MIR (I 21.6 / I 2.16 ) is about 29.5 and CDBI is about 36.1 wt %.

[0148] The second polyethylene composition is EXCEED TM 1327MA polyethylene composition, which is an ethylene / 1-hexene copolymer, is from ExxonMobil Chemical Company, Houston, Texas, USA. EXCEED TM The density of 1327MA is 0.927 g / cm3, the melt index is 1.3 g / 10 min, according to ASTM D1238 (190°C / 2.16 kg), and MIR (I 21.6 / I 2.16 ) is about 15.9 and CDBI is about 59.4 wt%.

[0149] CaCO3 masterbatch: Using Imerys The CaCO3 particle size is 2.0 μm.

[0150] Offline MDO for breathable backsheet films:

[0151] Formulations #1-5 (Table 1) were processed on a typical 3-layer blown MDO machine to produce blown films with the following characteristics.

[0152] Processing conditions for blown film:

[0153] Die diameter: 250mm; Die gap: 1.5mm

[0154] Screw diameter: 60 / 90 / 60mm; Screw length / diameter: 30

[0155] Extrusion temperatures for all three extrudates: 180°C, 185°C, 185°C and 185°C (185)°C for zones 1-4(5) and 185°C for screen pack

[0156] Die temperature: 185℃

[0157] Blow up ratio (BUR): 3.2 or 3.5;

[0158] Discharging rate: 120kg / h

[0159] Blown film thickness: 28-40μm

[0160] The wound blown film was then unwound and directed through an off-line MDO unit, the blown film so produced was stretched to 10-14 gsm and subsequently wound up.

[0161] MDO gap between fast traction roller and slow traction roller: 112mm;

[0162] MDO temperature: 70°C (preheating roller 1) / 80°C (preheating roller 2) / 85°C (preheating roller 3) / 90°C (slow pulling roller) / 90°C (fast pulling roller) / 105°C (annealing roller 1) / 105°C (annealing roller 2) / 100°C (annealing roller 3) / 70°C (cooling roller 1) / 60°C (cooling roller 2) / 50°C (cooling roller 3) / 40°C (cooling roller 4) / 30°C (cooling roller 5) / 30°C (cooling roller 6) / 30°C (cooling roller 7).

[0163] Winding speed: 100m / min

[0164] According to the method of the present invention, a base film is manufactured according to the formulation composition shown below: The basis weight in Table 1 represents the basis weight of the base film based on the total weight of the base film.

[0165] Formulations #1 to #5 all have a sandwich structure of skin layer / core layer / skin layer. The blown film thickness in Table 1 represents the overall thickness of the base film; for formulations #1 to #5, the thickness ratio of skin layer / core layer / skin layer is 1:2:1.

[0166] Formulation #1 (14 gsm coextrusion):

[0167] Surface layer: 70% CaCO3 MB + 15% Exceed TM 1327MA+15% Exceed TM XP 8358ML, and

[0168] Core layer: 70% CaCO3 MB + 15% Exceed TM 1327MA+15% Exceed TM XP 8358ML.

[0169] Formulation #2 (12 gsm coextrusion):

[0170] Surface layer: 70% CaCO3 MB + 15% Exceed TM 1327MA+15% Exceed TM XP 8358ML, and

[0171] Core layer: 70% CaCO3 MB + 15% Exceed TM 1327MA+15% Exceed TM XP 8358ML.

[0172] Formulation #3 (12 gsm coextrusion):

[0173] Surface layer: 70% CaCO3 MB + 15% Exceed TM XP 8358ML+15% Exceed TM 1327MA, and

[0174] Core layer: 70% CaCO3 MB + 10% Exceed TM XP 8358ML+10% Exceed TM 1327MA+10%PP.

[0175] Formulation #4 (12 gsm coextrusion):

[0176] Surface layer: 70% CaCO3 MB+20% Exceed TM XP 8358ML+10% Exceed TM 1327MA, and

[0177] Core layer: 70% CaCO3 MB + 5% Exceed TM XP 8358ML+10% Exceed TM 1327MA+15%PP.

[0178] Formulation #5 (10 gsm coextrusion):

[0179] Surface layer: 70% CaCO3 MB + 30% Exceed TM XP 8358ML, and

[0180] Core layer: 70% CaCO3 MB + 5% Exceed TM XP 8358ML+10% Exceed TM 1327MA+15%PP.

[0181] Table 1. Formulations #1-5 for 3L Off-line MDO Breathable Backsheet

[0182]

[0183] The measured film properties for Formulations #1-5 are summarized in Table 2.

[0184] Table 2. Breathable Backsheet Properties for Formulations #1-5

[0185]

[0186]

[0187] It is clear from Table 2 that compared with formulation #1, the only difference of formulation #3 is the addition of 10% PP in the core layer.

[0188] Comparing the performance of the base films made from formulation #1 and formulation #3, respectively, on the basis of comparable TD tensile strength, the base film made from formulation #3 successfully reduced the basis weight from 14 gsm to 12 gsm, a 14.3% reduction in basis weight, which brings significant cost advantages to manufacturers.

[0189] Moreover, compared with Formula #1, the base film made from Formula #3 successfully increased the WVTR from 4681 g / day / m2 to 5385 g / day / m2, an increase of 15.0%, which makes the base film have better breathability and brings a more comfortable feeling to the user.

[0190] It is clear from Table 2 that compared with formulation #2, the only difference of formulation #3 is the addition of 10% PP in the core layer.

[0191] Comparing the performance of the base films made from Formulation #2 and Formulation #3, respectively, on the basis of a basis weight of 12 gsm, the base film made from Formulation #3 performs equally well or even better in MD tensile properties. Moreover, the base film made from Formulation #3 has significantly improved TD tensile properties, with the TD tensile properties significantly improved by more than 17%.

[0192] Moreover, compared with Formula #2, the base film made from Formula #3 successfully increased the WVTR from 4365 g / day / m2 to 5385 g / day / m2, increasing the WVTR by 23.4%, which makes the base film have better breathability and brings a more comfortable feeling to the user.

[0193] Table 3. Comparison of the properties of the base films made from Formulation #2 and Formulation #3

[0194]

[0195] It is clear from Table 2 that compared to Formulation #4, Formulation #5 differs only in that the basis weight is reduced from 12 gsm to 10 gsm. One skilled in the art would generally expect that as the basis weight is reduced, the mechanical properties of the film will also be reduced.

[0196] However, the inventors of the present invention unexpectedly discovered that, compared to Formulation #4, despite reducing the basis weight from 12 gsm to 10 gsm, the base film made from Formulation #5 had significantly improved MD tensile strength (even by 21.6%) and MD / TD trouser tear (even by 12.4%), and further, the base film made from Formulation #5 also had significantly improved WVTR, which provides manufacturers with a wider range of formulation choices.

[0197] Table 4. Comparison of the properties of the base films made from Formulation #4 and Formulation #5

[0198]

[0199]

[0200] All documents described herein, including any priority documents and / or test procedures are introduced for reference under all jurisdictions that do not conflict with the present invention. It is obvious from the above overview and specific embodiments that, although the form of the present disclosure has been illustrated and described, various modifications can be made without departing from the spirit and scope of the present disclosure. Therefore, it is not desired that the present disclosure be limited in this way. Similarly, the term "comprising" is considered to be synonymous with the term "including". Similarly, whenever a composition, element or element group is in front of the transitional term "comprising", it should be understood that it is also considered to have the transitional term "essentially consisting of", "consisting of", "selected from" or "being" in front of the listed composition, element or each element The same composition or element group, and vice versa.

[0201] For simplicity, only some numerical ranges are clearly disclosed herein. However, a certain lower limit can be used in combination with any other upper limit to limit the scope that is not clearly recorded. Similarly, a certain lower limit can be used in combination with any other lower limit to limit the scope that is not clearly recorded. Similarly, a certain upper limit can also be used in combination with any upper limit to limit the scope that is not clearly recorded. In addition, even if there is no clear description, each point or individual value between the two end points is also included in the scope. Therefore, each point or individual value itself can be used as a lower limit or upper limit in combination with other points or individual values ​​or other lower or upper limits to limit the scope that is not clearly recorded.

Claims

1. A base film for sanitary products, comprising at least two surface layers and one core layer, wherein each of the surface layers comprises a first polyethylene composition, a second polyethylene composition and a CaCO3 masterbatch, and the core layer comprises a first polyethylene composition, a second polyethylene composition, a CaCO3 masterbatch and a polypropylene homopolymer, The polypropylene homopolymer has a melt index of 1-10 g / 10 min, preferably 1-5 g / 10 min, measured according to ASTM D1238 at 230° C. and 2.16 kg; and an isotactic index of 95-99.9%, preferably 96-99.9%, measured according to GB / T 2412-2008, wherein the core layer comprises the CaCO3 masterbatch in an amount of about 60 wt%-80 wt%, comprises the polypropylene homopolymer in an amount of about 5 wt%-30 wt%, and the balance is the first polyethylene composition and the second polyethylene composition, based on the total weight of the core layer.

2. The base film of claim 1, wherein the first polyethylene composition has a density of 0.910 g / cm3 to 0.920 g / cm3 and a melt index I of 0.4 to 1.0 g / 10 min. 2.16 ;and The second polyethylene composition has a density of 0.920 g / cm3 to 0.935 g / cm3 and a melt index I of 1.0 to 2.0 g / 10 min. 2.16 .

3. The base film according to claim 1 or 2, wherein the first polyethylene composition has a melt index ratio MIR of 20.0-35.0, and a composition distribution breadth index CDBI of 20 wt% to less than 50 wt%; and The second polyethylene composition has a melt index ratio MIR of 10.0-30.0, and a composition distribution breadth index CDBI of greater than 50 wt% to 80 wt%.

4. The base film according to any one of claims 1-3, wherein the CaCO3 masterbatch of the surface layer and the core layer is characterized in that the particle size range of CaCO3 is about 1.0-4.0 μm, preferably 1.2-2.4 μm, and more preferably 1.5-2.0 μm.

5. The base film according to any one of claims 1 to 4, wherein each of the surface layers comprises the first polyethylene composition and the first polyethylene composition in a total amount of 20 wt% to 40 wt%, and comprises the CaCO3 masterbatch in an amount of 60 wt% to 80 wt%, based on the total weight of the surface layer.

6. The base film according to any one of claims 1-5, wherein each of the surface layers consists of the first polyethylene composition, the second polyethylene composition and the CaCO3 masterbatch, and / or wherein the core layer consists of the first polyethylene composition, the second polyethylene composition, the CaCO3 masterbatch and the polypropylene homopolymer.

7. A base film for sanitary products, which consists of two surface layers and one core layer, wherein each of the surface layers consists of a first polyethylene composition, a second polyethylene composition and a CaCO3 masterbatch, and the core layer consists of a first polyethylene composition, a second polyethylene composition, a CaCO3 masterbatch and a polypropylene homopolymer, wherein the polypropylene homopolymer has a melt index of 3.2 g / 10 min, measured at 230° C. and 2.16 kg according to ASTM D1238; and an isotactic index of 97.2%, measured according to GB / T2412-2008, wherein the core layer comprises the CaCO3 masterbatch in an amount of about 60 wt% to 80 wt%, comprises the polypropylene homopolymer in an amount of about 5 wt% to 30 wt%, and the balance is the first polyethylene composition and the second polyethylene composition, based on the total weight of the core layer, wherein the CaCO3 masterbatch has a CaCO3 particle size of about 2.0 μm, The first polyethylene composition has a density of about 0.918 g / cm3, a melt index of about 0.50 g / 10 min measured according to ASTM D1238 (190°C / 2.16 kg), a melt index ratio (MIR) of about 29.5, and a melt index ratio (MIR) of about 1.

5. 21.6 / I 2.16 ) and a composition distribution breadth index CDBI of about 36.1 wt %, and The second polyethylene composition has a density of about 0.927 g / cm3, a melt index of about 1.3 g / 10 min measured according to ASTM D1238 (190°C / 2.16 kg), a melt index ratio MIR (I 21.6 / I 2.16 ) and a composition distribution breadth index CDBI of about 59.4 wt%.

8. A sanitary product comprising the base film of any one of claims 1 to 7, wherein the sanitary product is selected from the group consisting of disposable baby and adult diapers, incontinence pads, feminine care products, and combinations thereof.

9. A method for preparing the base film for sanitary products according to any one of claims 1 to 7, comprising blow-coextruding each layer of the base film and performing machine direction orientation (MDO).

10. Use of a polypropylene homopolymer in a base film for sanitary products comprising a first polyethylene composition, a second polyethylene composition and a CaCO3 masterbatch for improving the tensile properties of the base film, wherein the polypropylene homopolymer has a melt index of 1-10, preferably 1-5, measured under conditions of 230°C and 2.16 kg according to ASTM D1238; and an isotactic index of 95-99.9%, measured according to GB / T2412-2008.

11. Use of a polypropylene homopolymer in a base film for sanitary products comprising a first polyethylene composition, a second polyethylene composition and a CaCO3 masterbatch for reducing the basis weight of the base film, wherein the polypropylene homopolymer has a melt index of 1-10, preferably 1-5, measured under the conditions of 230°C and 2.16 kg according to ASTM D1238; and an isotactic index of 95-99.9%, measured according to GB / T2412-2008.

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