Stretch film

Abstract

The stretch film contains an olefin-based elastomer and an inorganic filler, has an air permeability of 5,000 s / 100 ml or less as measured by a king air permeability tester, and has a permanent set of 20% or less in at least one direction.

Description

Technical Field

[0001] This invention relates to a stretchable membrane. Background Technology

[0002] Stretch membranes are used in a wide range of fields, including hygiene products, sporting goods, and medical supplies, to improve operability and comfort (fit). Examples include underwear and other clothing, diaper waistbands, diaper side panels, leg gathers, incontinence products, sanitary napkins, bandages, surgical drapes, fastening straps, caps, swim trunks, sports protective gear, medical protective gear, and adhesive bandages.

[0003] As such a stretchable membrane, a stretchable membrane as described below is proposed, which, for example, comprises an olefin resin containing an olefin elastomer and a filler, wherein the filler content is 100 to 300 parts by weight relative to 100 parts by weight of the olefin resin, and the stretchable membrane has voids on its surface. Furthermore, it is described that, with the above-described configuration, a stretchable membrane with excellent stretchability and excellent air permeability can be provided (for example, see Patent Document 1).

[0004] Patent Document 1: Japanese Patent Publication No. 2016-204634 Summary of the Invention

[0005] -The technical problem the invention aims to solve-

[0006] However, in the stretchable membrane described in the aforementioned Patent Document 1, the olefin elastomer has stretchability but lacks breathability, which can cause stuffiness when wearing sanitary products, resulting in a reduced user experience.

[0007] Furthermore, this stretchable membrane is obtained by manufacturing an unstretched membrane using a material with added inorganic fillers such as calcium carbonate, followed by stretching the unstretched membrane. Generally, when inorganic substances are added to a resin and then stretched, separation occurs between the resin and the inorganic substances, creating pores and thus imparting air permeability. However, if the same treatment is performed on a stretchable material, the resin elongates, and no separation occurs between the resin and the inorganic substances, thus failing to exhibit air permeability. As a result, it is difficult to achieve both air permeability and stretchability.

[0008] Therefore, the present invention is made in view of the above-mentioned problems, and its object is to provide a stretchable membrane that can have both excellent stretchability and breathability.

[0009] -Technical solutions for solving technical problems-

[0010] To achieve the above objectives, the stretch membrane of the present invention contains an olefin elastomer and an inorganic filler, and the stretch membrane is characterized in that: the air permeability measured by the Wang Yan type air permeability tester is less than 5000s / 100ml, and the following permanent deformation in at least one direction is less than 20%.

[0011] (Permanent deformation of the stretch membrane)

[0012] Cut a strip of test material from the stretch membrane, 100 mm long along one direction and 25 mm long in a direction perpendicular to the stretch membrane. Fix the test material to the clamps of the testing machine with a clamping distance of 25 mm. Stretch the test material along its length at a speed of 254 mm / min until the elongation (elongation ratio) calculated by the following formula (1) reaches 100%. Then, rapidly shrink the test material at the same speed and calculate the permanent deformation [%] according to the following formula (2).

[0013] Elongation [%] = (L1 - L0) / L0 × 100 (1)

[0014] Permanent deformation [%] = (L2 - L0) / L0 × 100 (2)

[0015] Where L0 is the distance between the clamps before elongation (mm), L1 is the distance between the clamps after elongation (mm), and L2 is the distance between the clamps when the load (N / 25mm) of the test piece becomes 0 during shrinkage (mm).

[0016] -The Effects of the Invention-

[0017] According to the present invention, a stretchable membrane with both excellent elasticity and breathability, and a method thereof, can be provided. Attached Figure Description

[0018] Figure 1 This is a top view illustrating the stretchable membrane according to the first embodiment of the present invention;

[0019] Figure 2 This is a cross-sectional view used to illustrate the stretchable membrane according to the second embodiment of the present invention;

[0020] Figure 3 This is a top view illustrating the stretchable membrane according to the second embodiment of the present invention. Detailed Implementation

[0021] The stretchable membrane of the present invention will now be described in detail. It should be noted that the present invention is not limited to the following embodiments, and appropriate modifications can be made without changing the spirit of the invention.

[0022] (First Implementation)

[0023] The stretchable membrane of this embodiment is a film-shaped molded body containing olefin elastomer and inorganic filler.

[0024] <Olefin Elastomers>

[0025] Examples of olefin-based elastomers used in this invention include copolymers or homopolymers with olefins having 3 or more carbon atoms as the main component, and copolymers of ethylene and olefins having 3 or more carbon atoms as the main component.

[0026] More specifically, examples include: (1) α-olefin homopolymers such as propylene homopolymers and 1-butene homopolymers with low stereoregularity; (2) α-olefin copolymers such as propylene-ethylene copolymers, propylene-ethylene-1-butene copolymers, 1-butene-ethylene copolymers, 1-butene-propylene copolymers, 4-methylpentene-1-propylene copolymers, 4-methylpentene-1-1-butene copolymers, 4-methylpentene-1-propylene-1-butene copolymers, propylene-1-butene copolymers, ethylene-propylene copolymers, ethylene-hexene copolymers, and ethylene-octene copolymers; and (3) ethylene-α-olefin-diene terpolymers such as ethylene-propylene-ethylidene norbornene copolymers, ethylene-propylene-butadiene copolymers, and ethylene-propylene-isoprene copolymers. Furthermore, elastomers in which the above-mentioned elastomers are dispersed in a crystalline polyolefin matrix can also be used. It should be noted that one olefin elastomer can be used alone, or two or more can be used in combination.

[0027] Olefin elastomers are generally composed of hard segments that govern basic physical properties such as mechanical properties and soft segments that govern elasticity, which is a characteristic of rubber. Elastomers whose hard segments are composed of polypropylene are called propylene elastomers, and those whose hard segments are composed of polyethylene are called ethylene elastomers. Examples of soft segments in olefin elastomers include: EPDM, EPM, EBM, IIR, hydrogenated styrene-butadiene rubber (HSBR), NBR, and acrylic rubber (ACM). In the case of propylene elastomers, the content of propylene units relative to all units is preferably 70% to 95% by mass, more preferably 80% to 90% by mass. If the content of propylene units as hard segments is 70% by mass or more, the strength is increased, thus excellent formability is obtained; if it is 95% by mass or less, excellent elasticity is obtained due to the elasticity of the soft segments.

[0028] Furthermore, from the viewpoint of obtaining excellent elasticity, the content of olefin elastomer relative to the total elastic membrane is preferably 15% to 50% by mass, more preferably 20% to 40% by mass, in 100% by mass of the elastic membrane. If the content of propylene elastomer is within the above range, excellent elasticity can be obtained due to the elasticity of the soft segments contained in the elastomer.

[0029] <Inorganic fillers>

[0030] The inorganic filler is a component used to form through-pores through porosimetry. By performing a stretching treatment in a state containing the inorganic filler, the stretchable membrane of this embodiment can exhibit excellent air permeability.

[0031] Examples of inorganic fillers include: calcium carbonate, zeolite, silicon dioxide, titanium dioxide, calcium oxide, magnesium oxide, zinc oxide, clay, mica, barium sulfate, and magnesium hydroxide. It should be noted that one inorganic filler can be used alone, or two or more can be used in combination.

[0032] Furthermore, the content of the inorganic filler relative to the total content of the stretch membrane is preferably 50% to 70% by mass, more preferably 60% to 65% by mass, out of 100% by mass of the stretch membrane. If the content of the inorganic filler is within the above range, porosity is promoted by performing a stretching treatment.

[0033] Furthermore, the average particle size of the inorganic filler is preferably 0.8 to 15 μm. If the average particle size of the inorganic filler is 0.8 μm or more, secondary agglomeration of the inorganic filler is suppressed, resulting in good dispersibility in the resin. If it is 15 μm or less, openings caused by sag during extrusion will disappear, resulting in excellent formability.

[0034] It should be noted that the "average particle size" mentioned here refers to the particle size of 50% of the particle size distribution measured by a particle size analyzer.

[0035] <Other Ingredients>

[0036] Within the limits of not compromising the elasticity of the stretch membrane, the stretch membrane may also contain other components besides the aforementioned olefin elastomers.

[0037] Other components include: olefin resins, amide anti-sticking agents (such as stearamide), plasticizers, UV absorbers, antioxidants, weather stabilizers, antistatic agents, colorants, antifogging agents, metallic soaps, waxes, mildew inhibitors, antibacterial agents, nucleating agents, flame retardants, and lubricants. It should be noted that these other components can also be added to the material used for stretch membranes after masterbatch preparation.

[0038] <Olefin Resins>

[0039] As an olefin resin, a substance that is compatible with the aforementioned olefin elastomer is preferred; for example, polyethylene resin and polypropylene resin are preferred. It should be noted that one olefin resin may be used alone, or two or more may be used in combination.

[0040] For example, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and ultra-low-density polyethylene (ULDPE) can be used as polyethylene resins.

[0041] Furthermore, from the viewpoint of improving air permeability by aiding in pore immobilization, the content of olefin resin relative to the overall stretch membrane is preferably less than 10% by mass in 100% by mass of the stretch membrane. The reason is as follows: when the content of olefin resin is 10% by mass or more, since general polyethylene itself does not have stretchability, there is a situation where the stretchability of the membrane is significantly deteriorated.

[0042] It should be noted that, from the viewpoint of improving air permeability, it is preferable to use low-density polyethylene as the polyethylene resin, and the content of low-density polyethylene relative to the total mass of the stretch film is less than 10%.

[0043] <Through Hole>

[0044] Figure 1 This is a top view showing the stretchable membrane of this embodiment. Figure 1 As shown, a plurality of through holes 2 are formed on the stretchable film 1 of the present invention. As will be described later, the through holes 2 are formed by stretching the raw film before it is porous.

[0045] It should be noted that, in Figure 1 The diagram shows a stretchable membrane after stretching along its mechanical axis (length) direction (hereinafter referred to as "MD"). However, after stretching in a direction orthogonal to MD (hereinafter referred to as "TD"), a through-hole 2 with a longer transverse length along TD is formed.

[0046] Furthermore, in the stretch membrane 1 of this embodiment, it is configured such that: by stretching the original membrane while it contains the inorganic filler 3, porosity is achieved.

[0047] The diameter of the through hole 2 is preferably 1μm to 100μm. If the diameter is greater than 1μm, the hole will not be blocked in a stretchable material such as an elastomer, thus achieving excellent air permeability. If the diameter is less than 100μm, it can achieve waterproofing.

[0048] It should be noted that the diameter of through hole 2 is the average of the opening diameters of through holes 2 at 50 randomly selected locations.

[0049] <Manufacturing Method of Stretch Membrane>

[0050] Next, the manufacturing method of the stretch membrane according to this embodiment will be described in detail.

[0051] The stretch film of this embodiment is manufactured by forming a film from a raw material containing the above-mentioned olefin elastomer and inorganic filler using an extruder.

[0052] More specifically, firstly, olefin elastomers, inorganic fillers, and other components such as the aforementioned olefin resins added as needed are mixed in a prescribed ratio, and the mixture is extruded into a linear strand using a co-rotating twin-screw extruder including a strand die, and then cut to obtain granules.

[0053] Next, the particles are melt-extruded into a film using a single-screw extruder including a T-die, and the film is then wound with a winding roller to obtain the original film before it becomes porous.

[0054] Then, by subjecting the original membrane to uniaxial stretching, the original membrane is made porous, thereby manufacturing... Figure 1 The diagram shows a stretch film 1 with multiple through holes 2. It should be noted that the stretching method is not particularly limited; for example, roller stretching, spreader stretching, gear stretching, etc., can be listed.

[0055] Furthermore, the aforementioned uniaxial stretching process is along... Figure 1 The stretching process is performed in any of the MD and TD directions shown. It should be noted that biaxial stretching can also be performed, in which stretching is performed along both the MD and TD directions.

[0056] Furthermore, the stretching temperature during uniaxial stretching is above 20°C and below 70°C. The reasons are as follows: When the stretching temperature is below 20°C, the pores formed by the stretching properties of the olefin elastomer are blocked, resulting in insufficient moisture permeability. Additionally, when the stretching temperature is above 70°C, the stretching film may melt and break.

[0057] Furthermore, the stretching ratio during uniaxial stretching is between 1.8 and 6 times. The reasons are as follows: if the stretching ratio is above 1.8 times, it will promote porosity caused by the stretching process, further increasing the moisture permeability of the stretch membrane. However, if the stretching ratio is greater than 6 times, there is a possibility of breakage due to the elongated membrane. It should be noted that the "stretching ratio" mentioned here refers to the ratio of the length of the stretched membrane to the length of the membrane before stretching in the stretching direction.

[0058] Furthermore, the stretch membrane of this embodiment manufactured by the above method has an air permeability of less than 5000s / 100ml as measured by the Wang Yanshi air permeability tester, thus achieving excellent air permeability.

[0059] Furthermore, the permanent deformation of the stretch membrane in this embodiment is less than 20%, thus achieving excellent stretchability.

[0060] It should be noted that the "permanent deformation" mentioned here is a quantity calculated using the following method.

[0061] Cut a strip of test material from the stretch membrane, 100 mm long along one direction and 25 mm long along the other. Fix the test material onto the fixture of a precision universal testing machine (Autograph AG-5000A, manufactured by Shimadzu Corporation), with the distance between the fixtures being 25 mm. Then, stretch the test material along its length at a speed of 254 mm / min until the elongation (elongation ratio) calculated by the following formula (1) reaches 100%. Then, rapidly shrink the test material at the same speed. Then, calculate the permanent deformation [%] according to the following formula (2).

[0062] Elongation [%] = (L1 - L0) / L0 × 100 (1)

[0063] Permanent deformation [%] = (L2 - L0) / L0 × 100 (2)

[0064] Where L0 is the distance between the clamps before elongation (mm), L1 is the distance between the clamps after elongation (mm), and L2 is the distance between the clamps when the load (N / 25mm) of the test piece becomes 0 during shrinkage (mm).

[0065] Furthermore, the thickness of the original film before stretching is preferably 10–80 μm, more preferably 20–60 μm. If the thickness of the original film is 10 μm or more, operability such as wrinkles during winding and trimming during cutting can be ensured. In addition, if the thickness of the original film is less than 80 μm, the stretch film after stretching can obtain sufficient air permeability.

[0066] Furthermore, when heat stretching treatment is performed, the thickness of the stretched film after stretching treatment is 40-60% of the original film; when stretching treatment is performed at room temperature, the thickness of the stretched film after stretching treatment is 80-100% of the original film. Additionally, in the case of gear stretching, the thickness of the unstretched portion is equal to the original film thickness, and the thickness of the stretched portion is 80-100% of the original film thickness.

[0067] Through the above methods, a stretch membrane with both excellent elasticity and breathability can be obtained in this embodiment.

[0068] It should be noted that stretch membranes can be single-layered or multi-layered. When a stretch membrane is multi-layered, the composition and thickness of each layer can be the same or different. The thickness of a multi-layered stretch membrane refers to the overall thickness of that multi-layered membrane.

[0069] (Second Implementation)

[0070] Next, the second embodiment of the present invention will be described. It should be noted that the same reference numerals are used for the same components as in the first embodiment described above, and their descriptions are omitted.

[0071] Figure 2 This is a cross-sectional view showing the stretchable membrane according to the second embodiment of the present invention. Figure 2 As shown, the stretch membrane 10 of this embodiment includes: an elastomer layer 5, which is composed of a stretch membrane containing an olefin elastomer and an inorganic filler as described in the first embodiment above; and surface layers 6 and 7, which are stacked on the surface of the elastomer layer 5.

[0072] It should be noted that, within the range that does not impair the elasticity of the stretch membrane 10, the elastomer layer 5 may also contain other components described in the first embodiment above.

[0073] (Surface layer)

[0074] Surface layers 6 and 7 are layers used to suppress adhesion in the stretch membrane 10.

[0075] like Figure 2 As shown, surface layers 6 and 7 are disposed on either or both of the first and second surfaces of the elastomer layer 5. From the viewpoint of sufficiently suppressing adhesion of the stretch membrane 10, it is preferable that they are disposed on both the first and second surfaces of the elastomer layer 5. It should be noted that surface layers 6 and 7 can be the same type of surface layer or different types of surface layers.

[0076] Surface layers 6 and 7 contain olefin resins (other than olefin elastomers), and preferably further contain inorganic fillers. Furthermore, without impairing the effects of the invention, surface layers 6 and 7 may also contain other components as needed.

[0077] <Olefin Resins>

[0078] As an olefin resin, a substance compatible with the olefin elastomer in the elastomer layer 5 is preferred; for example, polyethylene resin or polypropylene resin is preferred. From the viewpoint of improving the elasticity of the surface layers 6 and 7, polyethylene is preferred, and from the viewpoint of improving the breathability of the surface layers 6 and 7, polypropylene resin is preferred.

[0079] For example, examples of polyethylene resins include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE).

[0080] Furthermore, examples of polypropylene resins include: homopolymer polypropylene (H-PP), which is synthesized by polymerizing propylene alone; random polypropylene (R-PP), which is copolymerized by copolymerizing ethylene and propylene; and block polypropylene (B-PP), which is synthesized by polymerizing homopolymer polypropylene and then copolymerizing ethylene and propylene in the presence of homopolymer polypropylene. It should be noted that olefin resins can be used alone or in combination with two or more.

[0081] Furthermore, from the viewpoint of obtaining excellent elasticity, the content of olefin resin relative to the total surface layer is preferably 30% to 60% by mass in 100% by mass of the surface layer, more preferably 40% to 50% by mass.

[0082] <Inorganic fillers>

[0083] The inorganic filler is a component used to impart sliding properties to the surfaces of the surface layers 6 and 7 to further suppress adhesion in the stretch membrane 10. Furthermore, it is a component used to form through-holes 2 through porousing. By performing stretching treatment in a state containing this inorganic filler, the stretch membrane of this embodiment exhibits excellent air permeability.

[0084] Examples of inorganic fillers include: calcium carbonate, zeolite, silicon dioxide, titanium dioxide, calcium oxide, magnesium oxide, zinc oxide, clay, mica, barium sulfate, and magnesium hydroxide. It should be noted that one inorganic filler can be used alone, or two or more can be used in combination.

[0085] Furthermore, the content of the inorganic filler relative to the total surface layer is preferably 40% to 70% by mass, more preferably 50% to 60% by mass, out of 100% by mass of the surface layer. If the content of the inorganic filler is within the above range, porosity is promoted by performing a stretching treatment.

[0086] The average particle size of the inorganic filler is preferably 0.8 to 10 μm. If the average particle size of the inorganic filler is above 0.8 μm, secondary agglomeration of the inorganic filler is suppressed, resulting in good dispersibility in the resin. If it is below 10 μm, the feel is good.

[0087] <Other Ingredients>

[0088] Other components include: amide-based anti-sticking agents (such as stearamide), plasticizers, UV absorbers, antioxidants, weather stabilizers, antistatic agents, colorants, antifogging agents, metallic soaps, waxes, mildew inhibitors, antibacterial agents, nucleating agents, flame retardants, and lubricants. It should be noted that these other components can also be added to the material used for stretch films after masterbatch preparation.

[0089] <Through Hole>

[0090] Figure 3 This is a top view showing the stretchable membrane of this embodiment. Figure 3 As shown, a plurality of through holes 2 are formed in the stretchable membrane 10 of the present invention. As will be described later, these through holes 2 are formed by stretching the original membrane before it is porous. Furthermore, in the stretchable membrane 10 of this embodiment, the porousing is achieved by stretching the original membrane while it contains the inorganic filler 3 described above.

[0091] It should be noted that, in Figure 3 The diagram shows a stretchable membrane that has been stretched on the MD. However, when the membrane has been stretched on the TD, a through-hole 2 with a longer transverse length along the TD is formed.

[0092] Furthermore, as described above, by including inorganic fillers in the surface layers 6 and 7, porosity can be promoted during the stretching process. Also, similar to the first embodiment described above, the diameter of the through-hole 2 is preferably 1 μm to 100 μm.

[0093] <Manufacturing Method of Stretch Membrane>

[0094] Next, the manufacturing method of the stretch membrane according to this embodiment will be described in detail.

[0095] Similar to the first embodiment described above, for the stretchable film of this embodiment, firstly, an olefin elastomer, an inorganic filler, and other components such as the aforementioned olefin resin, added as needed, are mixed in a predetermined ratio. This mixture is then extruded in a linear form using a co-rotating twin-screw extruder including a drawing die, and subsequently cut to obtain particles for forming the elastomer layer. Similarly, an olefin elastomer, and other components such as the inorganic filler added as needed, are mixed in a predetermined ratio. This mixture is then extruded in a linear form using a co-rotating twin-screw extruder including a drawing die, and subsequently cut to obtain particles for forming the surface layer.

[0096] Next, using an extruder including a T-die, the particles for forming the elastomer layer and the particles for forming the surface layer are extruded at a specified temperature. By means of a cast film process, a pre-porous film is obtained. The pre-porous film has an elastomer layer, a first surface layer disposed on a first surface of the elastomer layer, and a second surface layer disposed on a second surface of the elastomer layer.

[0097] Then, by subjecting the original film to uniaxial stretching at the same stretching temperature and stretching ratio as in the first embodiment described above, the original film is made porous, thereby manufacturing... Figure 3 The stretching membrane 10 shown has multiple through holes 2. It should be noted that there are no particular limitations on the stretching method; for example, roller stretching, spreader stretching, gear stretching, etc. can be listed.

[0098] Furthermore, the aforementioned uniaxial stretching process is along... Figure 3 The stretching process is performed in either of the MD and TD directions shown. It should be noted that biaxial stretching can also be performed, in which stretching is performed along both the MD and TD directions.

[0099] Furthermore, similar to the first embodiment described above, in the stretch membrane of this embodiment manufactured by the above method, the air permeability measured by the Wang Yan type air permeability tester is less than 5000s / 100ml, and the permanent deformation is less than 20%. Therefore, it is possible to obtain a stretch membrane that has both excellent stretchability and air permeability.

[0100] It should be noted that the thickness of the original film before stretching is preferably 10–80 μm, more preferably 20–60 μm. If the thickness of the original film is 10 μm or more, operability such as wrinkles during winding and trimming during cutting can be ensured. In addition, if the thickness of the original film is less than 80 μm, sufficient air permeability can be obtained.

[0101] Furthermore, the thickness of the elastomer layer 5 in the original membrane is preferably 10 to 70 μm, more preferably 20 to 50 μm. If the thickness of the elastomer layer 5 is 10 μm or more, sufficient stretchability can be obtained in the stretchable membrane 10 after stretching treatment. Furthermore, if the thickness of the elastomer layer 5 is 70 μm or less, sufficient air permeability can be obtained in the stretchable membrane 10 after stretching treatment.

[0102] Furthermore, the thickness of surface layers 6 and 7 in the original membrane is preferably 1 to 6 μm, more preferably 2 to 4 μm. If the thickness of surface layers 6 and 7 is 1 μm or more, adhesion in the stretch membrane 10 after stretching treatment can be sufficiently suppressed, and the air permeability of the stretch membrane 10 can be improved. Furthermore, if the thickness of surface layers 6 and 7 is 6 μm or less, sufficient stretchability of the stretch membrane 10 can be achieved. It should be noted that the thicknesses of surface layers 6 and 7 can be equal or unequal.

[0103] Furthermore, when heat stretching treatment is performed, the thickness of the stretched film 10 after stretching treatment is 40 to 60% of the original film; when stretching treatment is performed at room temperature, the thickness of the stretched film 10 after stretching treatment is 80 to 100% of the original film. Additionally, in the case of gear stretching, the thickness of the unstretched portion is equal to the thickness of the original film, and the thickness of the stretched portion is 80 to 100% of the thickness of the original film.

[0104] Furthermore, from the viewpoint of improving the elasticity of the stretchable membrane 10 with a relatively small ratio of the thickness of the surface layers 6 and 7 to the overall thickness of the stretchable membrane, it is preferable that the thickness ratio of the surface layer 6 (or surface layer 7) of the original membrane and the stretchable membrane 10 to the thickness of the elastomer layer 5 is surface layer: elastomer layer = 1:10 to 1:35.

[0105] It should be noted that stretch membranes can be single-layered or multi-layered. When a stretch membrane is multi-layered, the composition and thickness of each layer can be the same or different. The thickness of a multi-layered stretch membrane refers to the overall thickness of that multi-layered membrane.

[0106] Example

[0107] The present invention will now be described with reference to embodiments. It should be noted that the present invention is not limited to these embodiments, and modifications and alterations can be made to these embodiments according to the spirit of the present invention, and these modifications should not be excluded from the scope of the present invention.

[0108] The materials used in manufacturing stretch membranes are shown below.

[0109] (1) Inorganic filler: Calcium carbonate (manufactured by Shiraishi Calcium Kaisha, Ltd., trade name: PO-150B-10);

[0110] (2) LLDPE: Linear low-density polyethylene, density: 0.92 g / cm³ 3 MFR: 2.3g / 10 minutes (manufactured by Dow Chemical Company, trade name: Dowlex 2047G);

[0111] (3) HDPE: High-density polyethylene, density: 0.951 g / cm³ 3 MFR: 9.1g / 10 minutes (manufactured by Asahi Kasei Corp., trade name: Hizex2110JH);

[0112] (4) R-PP: Random polypropylene, density: 0.90 g / cm³ 3 MFR: 6.7g / 10 minutes (manufactured by Prime Polymer Co., Ltd., trade name: F227);

[0113] (5) Propylene elastomer (Vistamaxx (registered trademark) 6102FL (manufactured by Exxon Mobil Corporation, propylene-ethylene copolymer, ethylene unit content: 16% by mass);

[0114] (6) LDPE: Low-density polyethylene, density: 0.922 g / cm³ 3 MFR: 0.3g / 10 minutes (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumikathene, F101-1).

[0115] (Example 1)

[0116] <Manufacturing of Stretch Membrane>

[0117] First, the materials shown in Table 1 were mixed to prepare the material of Example 1 having the composition (parts by mass) shown in Table 1. Next, the material was extruded in strands and cut into granules at 200°C using a co-rotating twin-screw extruder (manufactured by The Japan SteelWorks, Ltd., trade name: TEX28V-42CW-4V) including a drawing die.

[0118] Next, the granules were formed into a film by melt extrusion (extrusion temperature: 200°C) using a single screw extruder (manufactured by NAGATA SEISAKUSYO Co., Ltd.) including a T-die. The film was then wound with a winding roller to obtain the original film before it became porous.

[0119] Then, under the stretching temperature and stretching ratio conditions shown in Table 1, the original film is subjected to uniaxial stretching along MD, thereby making the original film porous and producing a stretchable film with multiple through holes.

[0120] <Measurement of air permeability>

[0121] Next, the air permeability of the manufactured stretch film was measured using an Asahi Seiko air permeability meter (sec / 100cc) (manufactured by Asahi Seiko Co., Ltd., trade name: EG01-6-1MR). It should be noted that examples that did not exhibit air permeability in this measurement are marked as 99999 (sec / 100cc). The results are shown in Table 1.

[0122] <Measurement of Permanent Deformation>

[0123] A strip of test material, 100 mm long along one direction and 25 mm long in a direction perpendicular to the original stretch membrane, was cut from the manufactured stretch membrane. This strip was then fixed onto the fixtures of a precision universal testing machine (Autograph AG-5000A, manufactured by Shimadzu Corporation), with a 25 mm gap between the fixtures. The strip was then stretched along its length at a speed of 254 mm / min until the elongation (elongation ratio) calculated using equation (1) reached 100%. The strip was then rapidly contracted at the same speed. The permanent deformation [%] on MD and TD was then calculated according to equation (2). It should be noted that the test was conducted at room temperature (23℃ ± 2℃). The results are shown in Table 1.

[0124] (Examples 2-4)

[0125] Except for changing the composition (parts by mass) of the stretch film and the conditions of the uniaxial stretching process to those shown in Table 1, the original film having the thickness shown in Table 1 was stretched in the same manner as in Example 1 above to produce a stretch film.

[0126] Then, air permeability and permanent deformation were measured in the same manner as in Example 1 described above. The results are shown in Table 1.

[0127] (Example 5)

[0128] <Manufacturing of Stretch Membrane>

[0129] First, the materials shown in Table 1 were mixed to prepare materials for forming an elastomer layer and a surface layer, as shown in Table 1 (parts by mass), for Example 5. Next, the materials were extruded in strands and cut at 200°C using a co-rotating twin-screw extruder (manufactured by The Japan Steel Works, Ltd., trade name: TEX28V-42CW-4V) including a drawing die, to obtain granules for forming an elastomer layer and granules for forming a surface layer.

[0130] Next, using an extruder (manufactured by Sumitomo Heavy Industries Modern, Ltd.) including a T-die, granules for forming an elastomer layer and granules for forming a surface layer are extruded at 200°C. By casting a film, a film having an elastomer layer, a first surface layer disposed on a first surface of the elastomer layer, and a second surface layer disposed on a second surface of the elastomer layer is formed. By winding the film with a winding roller, the original film before porosification is obtained.

[0131] Then, under the stretching temperature and stretching ratio conditions shown in Table 1, the original film is subjected to uniaxial stretching along MD, thereby making the original film porous and producing a stretchable film with multiple through holes.

[0132] Then, the air permeability and permanent deformation were measured in the same manner as in Example 1 described above. The results are shown in Table 1.

[0133] (Examples 6-16)

[0134] Except for changing the composition (parts by mass) of the surface layer, the composition (parts by mass) of the elastomer layer, the thickness ratio of the surface layer to the elastomer layer, and the conditions of the uniaxial stretching process to those shown in Tables 1 and 2, the original film having the thicknesses shown in Tables 1 and 2 was stretched in the same manner as in Example 5 above to produce a stretchable film.

[0135] Then, air permeability and permanent deformation were measured in the same manner as in Example 1 described above. The results are shown in Tables 1 and 2.

[0136] (Comparative Examples 1 to 9)

[0137] Except for changing the composition (parts by mass) of the surface layer, the composition (parts by mass) of the elastomer layer, the thickness ratio of the surface layer to the elastomer layer, and the conditions of the uniaxial stretching process to those shown in Table 3, the original film having the thickness shown in Table 3 was stretched in the same manner as in Example 5 above to produce a stretchable film.

[0138] Then, air permeability and permanent deformation were measured in the same manner as in Example 1 described above. The results are shown in Table 3.

[0139] It should be noted that in Comparative Example 8, the thickness ratio of the surface layer to the elastomer layer of the original film is 1:38. Therefore, during the manufacturing of the original film, a portion of the surface layer does not extend to the elastomer layer, thus making it impossible to obtain a stretchable film.

[0140] Furthermore, in Comparative Example 9, due to the large amount of inorganic filler incorporated into the elastomer layer, it was impossible to manufacture particles for forming the elastomer layer.

[0141] Therefore, in Comparative Examples 8 and 9, air permeability and permanent deformation could not be measured.

[0142] [Table 1]

[0143]

[0144] [Table 2]

[0145]

[0146] [Table 3]

[0147]

[0148] As shown in Tables 1 to 2, it can be seen that in the stretch membranes of Examples 1 to 16, the air permeability measured by the Wang Yan type air permeability tester is less than 5000s / 100ml, and the permanent deformation in at least one direction of MD and TD is less than 20%, thus it can have both excellent stretchability and air permeability.

[0149] On the other hand, as shown in Table 3, it can be seen that in the stretch film of Comparative Example 1, the ratio of the thickness of the surface layer to the elastomer layer of the original film is 1:8. Therefore, the proportion of the surface layer increases and the proportion of the low-elasticity resin component increases, resulting in a lack of stretchability (permanent deformation greater than 20%).

[0150] Furthermore, in the stretching film of Comparative Example 2, the stretching temperature during film forming in the uniaxial stretching process was above 70°C, therefore, the stretching film melted and broke.

[0151] Furthermore, it is known that in the stretch film of Comparative Example 3, the thickness ratio of the surface layer to the elastomer layer of the original film was 1:8. Therefore, the proportion of the surface layer increased, and the proportion of the low-elasticity resin component increased, resulting in a lack of stretchability (permanent deformation greater than 20%). Additionally, it is known that due to the low stretch ratio, there were insufficient openings, resulting in a lack of air permeability (air permeability greater than 5000 s / 100 ml).

[0152] Furthermore, it is known that in the stretch membrane of Comparative Example 4, the stretching ratio during membrane formation in the uniaxial stretching process was less than 1.8 times. Therefore, it did not promote the porosity achieved by the uniaxial stretching process and lacked air permeability (air permeability greater than 5000s / 100ml).

[0153] Furthermore, it is known that in the stretch membrane of Comparative Example 5, the thickness ratio of the surface layer to the elastomer layer of the original membrane is 1:8, and no LDPE is incorporated into the elastomer layer. Therefore, it is difficult for separation to occur between the resin and the inorganic filler, resulting in poor air permeability (air permeability greater than 5000s / 100ml).

[0154] Furthermore, it is known that in the stretch membrane of Comparative Example 6, no LDPE was incorporated into the elastomer layer, therefore, separation between the resin and the inorganic filler was difficult to occur, and no air permeability was observed (the air permeability was marked as 99999s / 100ml).

[0155] Furthermore, it is known that in the stretch membrane of Comparative Example 7, LDPE was not incorporated into the elastomer layer, therefore, separation between the resin and the inorganic filler was difficult to occur, resulting in a lack of air permeability (air permeability greater than 5000s / 100ml).

[0156] -Industry Applicability-

[0157] In summary, the present invention is suitable for use in, for example, clothing such as underwear, waistbands for diapers, side panels of diapers, leg pleats, incontinence products, sanitary napkins, bandages, surgical coverings, fastening straps, hats, swim trunks, sports protective gear, medical protective gear, adhesive bandages, etc., and methods for manufacturing the same.

[0158] -Symbol Explanation-

[0159] 1. Stretch membrane

[0160] 2 Through holes

[0161] 3 Inorganic fillers

[0162] 5. Elastomer layer

[0163] 6, 7 Surface layer

[0164] 10. Stretch membrane.

Claims

1. A stretchable membrane comprising an olefinic elastomer and an inorganic filler, characterized in that: The content of the olefin elastomer relative to the total content of the stretch membrane is more than 15% by mass and less than 50% by mass in 100% of the stretch membrane. The inorganic filler, relative to the total content of the stretch membrane, accounts for more than 50% and less than 65% by mass in 100% by mass of the stretch membrane. The stretch film contains low-density polyethylene, and the content of low-density polyethylene relative to the total content of the stretch film is less than 10% by mass in 100% by mass of the stretch film. The air permeability measured by Wang Yanshi's air permeability tester is below 5000s / 100ml. The following permanent deformations in at least one direction are less than 20%: (Permanent deformation of the stretch membrane) Cut a strip of test material from the stretch membrane, 100 mm long along one direction and 25 mm long in a direction perpendicular to the stretch membrane. Fix the test material to the clamps of the testing machine with a clamping distance of 25 mm. Stretch the test material along its length at a speed of 254 mm / min until the elongation (elongation ratio) calculated by the following formula (1) reaches 100%. Then, rapidly shrink the test material at the same speed and calculate the permanent deformation [%] according to the following formula (2). Elongation [%] = (L1 - L0) / L0 × 100 (1) Permanent deformation [%] = (L2 - L0) / L0 × 100 (2) Where L0 is the distance between the clamps before elongation (mm), L1 is the distance between the clamps after elongation (mm), and L2 is the distance between the clamps when the load (N / 25mm) of the test piece becomes 0 during shrinkage (mm).

2. A stretchable membrane comprising an elastomer layer containing an olefinic elastomer and an inorganic filler, and a surface layer laminated on at least one side of the elastomer layer, characterized in that: The olefinic elastomer comprises, relative to the total elastomer layer, 15% to 50% by mass out of 100% by mass of the elastomer layer. The inorganic filler, relative to the total content of the elastomer layer, accounts for more than 50% and less than 65% by mass in 100% by mass of the elastomer layer. The elastomer layer contains low-density polyethylene, and the content of low-density polyethylene relative to the total elastomer layer is less than 10% by mass in 100% of the elastomer layer. The air permeability measured by the Wang Yan-type air permeability tester is below 5000s / 100ml. The following permanent deformations in at least one direction are less than 20%: (Permanent deformation of the stretch membrane) Cut a strip of test material from the stretch membrane, 100 mm long along one direction and 25 mm long in the direction perpendicular to the stretch membrane. Fix the test material to the clamps of the testing machine with a clamping distance of 25 mm. Stretch the test material along its length at a speed of 254 mm / min so that the elongation (elongation ratio) calculated by the following formula (3) reaches 100%. Then, rapidly shrink the test material at the same speed and calculate the permanent deformation [%] according to the following formula (4). Elongation [%] = (L1 - L0) / L0 × 100 (3) Permanent deformation [%] = (L2 - L0) / L0 × 100 (4) Where L0 is the distance between the clamps before elongation (mm), L1 is the distance between the clamps after elongation (mm), and L2 is the distance between the clamps when the load (N / 25mm) of the test piece becomes 0 during shrinkage (mm).

3. The stretchable membrane according to claim 2, characterized in that: The thickness ratio of the surface layer to the elastomer layer is 1:10 to 1:

35.

4. The stretchable membrane according to claim 1 or 2, characterized in that: The stretch membrane is stretched in at least one direction.

5. The stretchable membrane according to claim 1 or 2, characterized in that: The olefin elastomer is a propylene elastomer.

6. The stretchable membrane according to claim 1 or 2, characterized in that: Multiple through holes are formed on the stretch membrane.

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