JP7219595B2 - laminated film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a porous film and a laminated film comprising the same.

BACKGROUND ART Laminated films obtained by attaching a non-woven fabric to a porous film are known as bag-constituting members for use in disposable body warmers and the like. Patent Document 1 proposes such a porous film.

US Pat. No. 5,300,000 discloses a porous film comprising a resin composition containing a linear low density polyethylene resin, a filler and an olefin terpolymer. The porous film of Patent Document 1 has good mechanical strength and little unevenness.

By the way, in recent years, there has been proposed a steam heating mask represented by "MegRhythm (registered trademark)" that applies warm steam to a target part such as the mouth (see Patent Document 2). This steam thermal mask contains a thermal steam generator (for example, a set of a disposable body warmer and a water-retaining sheet), and the steam generator is placed in the center of the mask so that exhaled air can pass through it. there is

JP-A-63-295649 JP 2017-225813 A

Since exhaled air passes through the steam generating portion of the steam heat mask, it is required to be designed so that it is easy to breathe. However, when the porous film of Patent Document 1 is used in a disposable body warmer for a steam generating part, the air permeability is insufficient, resulting in difficulty in breathing.

An object of the present invention is to provide a porous film and a laminated film having high air permeability.

The present invention [1] is a porous film comprising a resin composition containing a linear low-density polyethylene resin, a filler and an olefin terpolymer, wherein the filler is surface-treated with a fatty acid-based dispersant, It includes a porous film in which the filler has an average particle size of 5 μm or more.

The present invention [2] is the porous film according to [1], wherein the content of the filler is 200 parts by mass or more and 300 parts by mass or less with respect to 100 parts by mass of the linear low-density polyethylene resin. including.

The present invention [3] includes a laminated film comprising the porous film of [1] or [2] and a nonwoven fabric disposed on one side in the thickness direction of the porous film.

The present invention [4] includes the laminated film according to [3], which has an Oken air permeability of 500 sec/100 cc or less.

According to the porous film of the present invention and the laminated film comprising the same, the filler is surface-treated with a fatty acid-based dispersant, and the average particle size of the filler is 5 μm or more. temperament).

FIG. 1 shows a perspective view of one embodiment of the porous film of the present invention. FIG. 2 shows a cross-sectional side view of a laminated film comprising the porous film shown in FIG. FIG. 3 shows a side sectional view of a hand warmer with the laminated film shown in FIG.

In FIG. 2, the vertical direction of the paper is the vertical direction (thickness direction, first direction), the upper side of the paper is the upper side (one side in the thickness direction, the one side of the first direction), and the lower side of the paper is the lower side (thickness direction). the other side, the other side in the first direction). Moreover, the left-right direction and the depth direction on the paper surface are plane directions orthogonal to the up-down direction. Specifically, it conforms to the directional arrows in each figure.

1. Porous Film As shown in FIG. 1, a porous film 1, which is one embodiment of the present invention, has a film shape (including a sheet shape) having a predetermined thickness and extends in a plane direction perpendicular to the vertical direction. , has a flat top surface and a flat bottom surface.

The porous film 1 is formed into a film form from a resin composition containing a linear low density polyethylene resin, a filler and an olefin terpolymer.

Linear low density polyethylene resins are copolymers of ethylene and α-olefins.

Examples of α-olefins include 1-butene, 1-hexene, 1-octene, 4-methylpentene-1 and the like.

The density of the linear low-density polyethylene resin is, for example, 910 kg/m ³ or more and 925 kg/m ³ or less.

The melt flow rate (MFR) of the linear low-density polyethylene resin is, for example, 1.0 g/10 min or more, preferably 1.5 g/10 min or more, and for example, 10 g/10 min or less, preferably 5.5 g/10 min or more. 0 g/10 min or less. MFR is obtained under the condition of a load of 2.16 kg by a measuring method based on JIS K7210 (1999).

The content of the linear low-density polyethylene resin is, for example, 5% by mass or more, preferably 15% by mass or more, and, for example, 50% by mass or less, preferably 40% by mass, relative to the total amount of the resin composition. % or less.

Examples of fillers include inorganic fillers such as calcium carbonate, talc, clay, kaolin, silica, barium sulfate, kaolin sulfate, aluminum hydroxide, zinc oxide, calcium oxide, titanium oxide, alumina and mica. Calcium carbonate is preferred.

The average particle size of the filler is 5 μm or more, preferably 10 μm or more, more preferably 15 μm or more. Also, the average particle size of the filler is, for example, 30 μm or less, preferably 25 μm or less, more preferably 20 μm or less. If the average particle size of the filler is less than the above lower limit, the air permeability is insufficient. Further, if the average particle size of the filler exceeds the above upper limit, large pores may occur when the resin composition is extruded into a sheet and stretched, and the porous film may tear.

The average particle size of the filler is calculated from the median size by laser diffraction/scattering method.

The filler is surface-treated with a fatty acid-based dispersant. That is, a fatty acid-based dispersant is attached to the surface of the filler. Thereby, breathability can be improved.

Fatty acid-based dispersants include, for example, fatty acids, fatty acid esters, and fatty acid amides.

Fatty acids include linear or branched saturated or unsaturated fatty acids, specifically propionic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, acrylic acid, oleic acid. , linoleic acid, arachidonic acid and the like.

Examples of fatty acid esters include fatty acid methyl esters, glycerin fatty acid esters, sorbitan fatty acid esters, and sucrose fatty acid esters. Fatty acid esters include fatty acid esters and ethers obtained by adding ethylene oxide and the like thereto. Fatty acid methyl esters are preferred.

Examples of fatty acid amides include fatty acid amidopropyl betaine such as cocamidopropyl betaine and cocamidopropyl hydroxysultaine.

Fatty acid-based dispersants can be used alone or in combination of two or more. Fatty acid-based dispersants preferably include fatty acid esters.

The decomposition temperature of the fatty acid-based dispersant is, for example, 100° C. or higher, preferably 150° C. or higher, and is, for example, 300° C. or lower, preferably 250° C. or lower. Also, the melting point is, for example, 20° C. or higher, preferably 40° C. or higher, and for example, 80° C. or lower, preferably 60° C. or lower.

The filler is surface-treated by adding a fatty acid-based dispersant to the filler and mixing. In this case, the fatty acid-based dispersant may be solid such as powder, or may be liquid.

The adhesion ratio of the fatty acid-based dispersant is, for example, 0.1 parts by mass or more, preferably 1 part by mass or more, and for example, 10 parts by mass or less, preferably 5 parts by mass, with respect to 100 parts of the filler. It is below the department.

The content of the filler is, for example, 40% by mass or more, preferably 60% by mass or more, and is, for example, 80% by mass or less, preferably 70% by mass or less, relative to the total amount of the resin composition. . Further, the content ratio of the filler is, for example, 200 parts by mass or more, preferably 230 parts by mass or more, more preferably 260 parts by mass or more with respect to 100 parts by mass of the linear low-density polyethylene resin, and For example, it is 300 parts by mass or less, preferably 280 parts by mass or less. If the content of the filler is at least the above lower limit, the air permeability can be further improved. Further, when the content of the filler is equal to or less than the above upper limit, when the resin composition is extruded in the form of a sheet, the film formability can be improved, and a uniform film can be formed.

Olefin terpolymers are copolymers of three or more monomers, including an olefin monomer. Olefin terpolymers include, for example, copolymers of monomer components including ethylene, α-olefins (eg, propylene, 1-butene), and monomers having double bonds (eg, dienes). Preferred are copolymers of monomer components containing ethylene, propylene or 1-butene, and dienes (that is, EPDM-based polymers).

Examples of dienes constituting the EPDM polymer include 5-ethylidene-2-norbornene, dicyclopentadiene, 1,4-cyclohexadiene, 1,4-cycloheptadiene, 1,3-cyclooctadiene, 1, 5-cyclooctadiene, 1,6-cyclododecadiene, 1,7-cyclododecadiene, 1,5,9-cyclododecatriene, norbornadiene, methylene norbornene, methyl-tetrahydroindene, 1,4-hexadiene, 1, 5-hexadiene, 1,6-heptadiene, 2-methylpentadiene-1,4 and the like. Preferred is 5-ethylidene-2-norbornene.

The content of dienes (diene content) is, for example, 2.0% or more, preferably 7.0% or more, and for example, 15.0% or less, preferably 12.0% or less. When the diene content is at least the above lower limit, the mechanical strength of the porous film 1 is excellent. Diene content can be measured according to ASTM D 6047, for example.

The Mooney viscosity (ML(1+4) 100° C.) of the olefin terpolymer is, for example, 5 or more, preferably 10 or more, and for example, 90 or less, preferably 50 or less. Mooney viscosity can be measured according to ASTM D 1646, for example.

The content of the olefin terpolymer is, for example, 1% by mass or more, preferably 5% by mass or more, and for example, 20% by mass or less, preferably 15% by mass or less, relative to the total amount of the resin composition. be. Further, the content of the olefin terpolymer is, for example, 5 parts by mass or more, preferably 20 parts by mass or more, and for example, 200 parts by mass or less, preferably, relative to 100 parts by mass of the linear low-density polyethylene resin. is 90 parts by mass or less. If the content of the olefin terpolymer is within the above range, the mechanical strength of the porous film 1 will be excellent.

The resin composition may contain an antifoaming agent in an appropriate proportion in addition to the above components. As a result, it is possible to suppress the occurrence of cracks in the porous film 1 due to foaming due to moisture contained in the filler during the production of the porous film 1 .

Antifoaming agents include, for example, alkaline earth metal oxides such as calcium oxide, magnesium oxide, beryllium oxide, strontium oxide, barium oxide and zinc oxide. The antifoaming agent can be used alone or in combination of two or more.

In addition to the above components, the resin composition may contain known additives such as softeners, antioxidants, ultraviolet stabilizers, antistatic agents, pigments, lubricants, and fluorescent agents in appropriate proportions. can.

2. Method for producing porous film In the method for producing porous film 1, first, the above-described components are blended in the above-described content ratios, and, for example, a mixing roll, a pressure kneader, a Banbury mixer, a knitted shell mixer, and a twin-screw kneader. Melt and knead with a kneader such as a machine to prepare a kneaded product.

The melting temperature of the kneaded material (resin composition) may be lower than the decomposition temperature of the fatty acid-based dispersant, and is, for example, 100° C. or higher and 200° C. or lower.

Next, the resulting kneaded product is formed into a resin composition into a sheet by, for example, a calendar method, melt extrusion molding (inflation method, T-die method, etc.), press method, or the like.

Next, the sheet-shaped resin composition is stretched. The stretching may be uniaxial stretching or biaxial stretching. By stretching, gaps (voids) are generated in the sheet-like resin composition starting from locations where the filler is present, and as a result, the sheet-like resin composition is made porous.

The draw ratio in uniaxial stretching is, for example, 2.0 times or more, preferably 3.0 times or more, and is, for example, 10 times or less, preferably 5.0 times or less. The draw ratio in the biaxial stretching is, for example, 1.5 times or more, preferably 2.0 times or more, and, for example, 5.0 times with respect to the drawing direction (MD direction or TD direction). Below, preferably 4.0 times or less.

Heating is preferably carried out in order to easily stretch the resin composition. The heating temperature may be the melting temperature or lower, for example, 50° C. or higher, preferably 80° C. or higher, and for example, 150° C. or lower, preferably 120° C. or lower.

Thereby, the porous film 1 is obtained.

The thickness of the porous film 1 is, for example, 10 μm or more, preferably 50 μm or more, and for example, 500 μm or less, preferably 300 μm or less.

The air permeability (Oken formula) of the porous film 1 is, for example, 500 sec/100 cc or less, preferably 100 sec/100 cc or less, more preferably 50 sec/100 cc or less, and for example, 10 sec/100 cc or more. be. The air permeability can be measured using an Oken type air permeability meter.

Since this porous film 1 is formed from a resin composition containing a linear low-density polyethylene resin, a filler and an olefin terpolymer, it has excellent mechanical strength. In addition, since the filler is surface-treated with a fatty acid-based dispersant and the average particle size of the filler is 5 μm or more, air permeability is excellent.

This porous film 1 can be used, for example, as one member of a laminated film to be described later.

3. Laminated Film As shown in FIG. 2, a laminated film 2 according to one embodiment of the present invention is formed by bonding a porous film 1 and a nonwoven fabric 3 together. , an adhesive layer 4, and a nonwoven fabric 3 are provided in this order in the thickness direction. That is, the laminated film 2 includes a porous film 1 , an adhesive layer 4 arranged on the porous film 1 , and a nonwoven fabric 3 arranged on the adhesive layer 4 .

An adhesive layer 4 is partially arranged on the upper surface of the porous film 1 . That is, the pattern (planar view shape) of the adhesive layer 4 includes, for example, a dot shape, a stripe shape, a lattice shape, a sea-island shape, and the like.

The basis weight (application amount) of the adhesive layer 4 is, for example, 0.1 g/m ² or more, preferably 1 g/m ² or more, and for example, 10 g/m ² or less, preferably 5 g/m ² . It is below.

Examples of the adhesive layer 4 include hot-melt adhesives, pressure-sensitive adhesives, and thermosetting adhesives. Hot melt adhesives are preferred.

Examples of hot-melt adhesives include ethylene-vinyl acetate-based hot-melt, olefin-based hot-melt, rubber-based hot-melt, and polyamide-based hot-melt.

Examples of pressure sensitive adhesives (adhesives) include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, polyamide adhesives, vinyl alkyl ether adhesives, Fluorine-based pressure sensitive adhesives and the like are included.

Examples of thermosetting adhesives include epoxy thermosetting adhesives, urethane thermosetting adhesives, silicone thermosetting adhesives, and acrylic thermosetting adhesives.

The adhesives can be used singly or in combination of two or more.

The nonwoven fabric 3 is arranged on the upper surface of the adhesive layer 4 . The planar view shape of the nonwoven fabric 3 is substantially the same shape as the porous film 1 .

The nonwoven fabric 3 is made of, for example, natural fibers such as cotton, wool, hemp, pulp, silk, and mineral fibers, such as polyester fibers (eg, polyethylene terephthalate fibers), rayon, nylon fibers, vinylon fibers, acrylic fibers, aramid fibers, and polypropylene. It is formed from chemical fibers such as fibers, for example fibers such as glass fibers. Among these, from the viewpoint of heat resistance, chemical resistance, handleability, etc., chemical fibers are preferred, and polyester fibers are more preferred.

Methods of manufacturing the nonwoven fabric 3 include, for example, a dry method, a wet method, a spunbond method, a thermal bond method, a chemical bond method, a stitch bond method, a needle punch method, a melt blow method, a spunlace method, and a steam jet method. A spunbond method is preferred.

The basis weight of the nonwoven fabric 3 is, for example, 10 g/m ² or more, preferably 20 g/m ² or more, and is, for example, 100 g/m ² or less, preferably 50 g/m ² or less.

The thickness of the nonwoven fabric 3 is, for example, 5 μm or more, preferably 10 μm or more, and is, for example, 500 μm or less, preferably 300 μm or less.

Laminated film 2 is prepared, for example, by preparing porous film 1 and partially arranging adhesive layer 4 on the upper surface thereof by a known coating method (for example, spray method, die coater method, roll coater method). , subsequently by placing a nonwoven fabric 3 on its upper surface.

When using a hot-melt adhesive or a thermosetting adhesive, the adhesive layer 4 is heated as necessary.

The air permeability (Oken type) of the laminated film 2 is, for example, 500 sec/100 cc or less, preferably 100 sec/100 cc or less, more preferably 50 sec/100 cc or less, and for example, 10 sec/100 cc or more. . If the air permeability of the laminated film 2 is equal to or less than the above upper limit, the breathability is good, and even if the laminated film 2 is brought into contact with the mouth, it is easy to breathe.

The thickness of the laminated film 2 is, for example, 20 μm or more, preferably 100 μm or more, and is, for example, 800 μm or less, preferably 500 μm or less.

4. Application The laminated film 2 can be used, for example, as a bag for a disposable body warmer. From the viewpoint of excellent breathability, it is suitable for use in a disposable body warmer bag that is housed in a steam heating device (for example, a steam heating mask).

When the laminated film 2 is used as a bag body for a disposable body warmer (preferably a warmer for a steam mask), as shown in FIG. It comprises a film 6 and a heating element 7 arranged therebetween.

The planar view shape of the opposing film 6 is substantially the same shape as the laminated film 2 . The opposing film 6 is arranged on one side in the thickness direction of the laminated film 2 so that one side in the thickness direction faces the porous film 1 .

Examples of the facing film 6 include the nonwoven fabric 3 described above, the laminated film 2 described above, and plastic films such as polyolefin films and polyester films.

The peripheral edge portion of the facing film 6 and the peripheral edge portion of the laminated film 2 are joined to each other with an adhesive or the like. Thus, the opposed film 6 and the laminated film 2 are integrated to form a bag.

The heating element 7 is a heat generating material containing iron powder or the like, and is accommodated between the facing film 6 and the laminated film 2 .

EXAMPLES Examples and comparative examples are shown below to describe the present invention more specifically. In addition, the present invention is not limited to Examples and Comparative Examples. In addition, specific numerical values such as the mixing ratio (content ratio), physical property values, and parameters used in the following description are the corresponding mixing ratios ( content ratio), physical properties, parameters, etc. be able to.

(Example 1)
Calcium carbonate was surface-treated by mixing 100 parts by mass of calcium carbonate (average particle size: 12.3 μm) with 3 parts by mass of fatty acid-based dispersant (fatty acid methyl ester, decomposition temperature: 200° C., melting point: 50° C.).

250 parts by mass of surface-treated calcium carbonate, 100 parts by mass of linear low-density polyethylene (“Ultzex 2022L”, manufactured by Prime Polymer Co., Ltd., 919 kg/m ³ , MFR 2.0 g/10 min), and olefin terpolymer (manufactured by Mitsui Chemicals , "EPT K-9720", ethylene / 1-butene / 5-ethylidene-2-norbornene terpolymer, Mooney viscosity 20 (ML (1 + 4) 100 ° C.), diene content 10.4%) 40 parts by mass, A resin composition was obtained by melt-kneading at 160°C.

The resulting resin composition was melt extruded by a T-die method, and stretched in the longitudinal direction (conveyance direction) at a stretching temperature of 100° C. by a uniaxial roll stretching method so that the stretch ratio would be 4.0 times. Thereby, a porous film having a thickness of 120 μm was obtained.

Spunbond polyester nonwoven fabric is partially coated with a hot-melt thermoplastic copolyamide-based adhesive by a spray method, and a porous film is placed on the upper surface of the adhesive to form a porous film on the nonwoven fabric. pasted together. Thus, a laminated film of Example was obtained.

(Example 2)
A laminated film was obtained in the same manner as in Example 1, except that the content of calcium carbonate was changed to 280 parts by mass with respect to 100 parts by mass of linear low-density polyethylene.

(Example 3)
A laminate film was obtained in the same manner as in Example 1, except that the average particle size of calcium carbonate was changed to 20.6 μm.

(Comparative example 1)
A laminate film was obtained in the same manner as in Example 1, except that the average particle size of calcium carbonate was changed to 3.4 μm.

(Comparative example 2)
A laminate film was obtained in the same manner as in Example 1, except that the calcium carbonate was not surface-treated.

(Comparative Example 3)
A laminate film was obtained in the same manner as in Example 1, except that the average particle size of calcium carbonate was changed to 3.4 μm and the calcium carbonate was not surface-treated.

<Method for measuring air permeability>
The air permeability of the laminated film of each example and each comparative example was measured using an Oken type air permeability meter (“EG01-7-7MR” manufactured by Asahi Seiko Co., Ltd.). 05 MPa and a measurement area of 75 mmφ The results are shown in Table 1.

1 Porous film 2 Laminated film 3 Nonwoven fabric

Claims (2)

a porous film comprising a resin composition containing a linear low density polyethylene resin, a filler and an olefin terpolymer;
A nonwoven fabric arranged on one side in the thickness direction of the porous film
with
The filler is surface-treated with a fatty acid-based dispersant,
The average particle size of the filler is 5 μm or more,
The porous film is a uniaxially stretched porous film ,
A laminated film having an Oken air permeability of 500 sec/100 cc or less . 2. The laminated film according to claim 1, wherein the content of said filler is 200 parts by mass or more and 300 parts by mass or less with respect to 100 parts by mass of said linear low-density polyethylene resin.

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