JP7168333B2 - Moisture-permeable film and packaging - Google Patents

Description

The present invention relates to moisture permeable films and packages.

A film formed from a resin composition containing a thermoplastic resin and a filler is known as a moisture-permeable film.
Techniques related to such moisture-permeable films include, for example, those described in Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2017-31293).

In Patent Document 1, 25 to 75 parts by mass of polyethylene resin (A), 75 to 25 parts by mass of inorganic filler (B), and the total amount of 100 parts by mass of (A) and (B) and an ester plasticizer (C) in an amount of 0.5 to 5 parts by mass, wherein the resin composition is melted by heating to eliminate voids in the air-permeable film. 0.5 to 10 parts by mass of the partially blocking ventilation inhibitor (D) is contained with respect to 100 parts by mass of the total amount of (A) and (B), and the air permeability is 1,000 to 45,000. It describes a breathable film characterized by an air permeability increase rate of 1.5 to 5.0 when heat-treated at 90° C. for 30 minutes at 90° C. for 30 minutes per second/100 mL.
Patent Document 1 discloses that the breathable film having the above structure has the function of increasing the air permeability when heated, and is used as a sheet of sanitary material, protective clothing, work clothes, a desiccant, and a storage bag for a moisture absorbent. It is described that it can be suitably used as

JP 2017-31293 A

According to the studies of the present inventors, the moisture-permeable film formed from a resin composition containing a thermoplastic resin and a filler causes poor sticking to the chill roll and stains on the roll during continuous film formation. It has become clear that the continuous film-forming property and the appearance are inferior.
Furthermore, it is difficult to highly control the moisture permeability level of a moisture permeable film formed from a resin composition containing a thermoplastic resin and a filler while maintaining basic properties such as mechanical properties.

The present invention has been made in view of the above circumstances, and provides a moisture-permeable film that is excellent in continuous film-forming properties and appearance, and whose moisture permeability can be controlled to a high degree.

The present inventors have made intensive studies to solve the above problems. As a result, by providing a resin layer having a total thickness of 10 μm or less on the surface of the biaxially stretched film layer containing a thermoplastic resin and a filler, the total thickness of the resin layer can be maintained while maintaining good continuous film-forming properties and appearance. The inventors have found that the moisture permeability can be controlled to a high degree by the thickness, resulting in the present invention.

That is, according to the present invention, the following moisture-permeable film and package are provided.

[1]
a biaxially stretched film layer (A) containing a thermoplastic resin and at least one filler selected from organic fillers and inorganic fillers;
A surface resin layer (B) provided on at least one surface of the biaxially stretched film layer (A),
A moisture-permeable film, wherein the surface resin layer (B) has a total thickness of 10 µm or less.
[2]
In the moisture-permeable film according to [1] above,
A moisture-permeable film in which the content of the filler in the biaxially stretched film layer (A) is 40% by mass or more and 70% by mass or less when the entire biaxially stretched film layer (A) is taken as 100% by mass. .
[3]
In the moisture-permeable film according to [1] or [2] above,
A moisture-permeable film in which the thermoplastic resin contains a polyolefin resin.
[4]
In the moisture-permeable film according to [3] above,
A moisture-permeable film in which the polyolefin-based resin contains at least one selected from polyethylene-based resins and polypropylene-based resins.
[5]
In the moisture-permeable film according to any one of [1] to [4] above,
The biaxially stretched film layer (A) is a moisture-permeable film having air holes on its surface.
[6]
In the moisture-permeable film according to any one of [1] to [5] above,
The filler is calcium carbonate, calcium sulfate, barium carbonate, barium sulfate, titanium oxide, magnesium hydroxide, magnesium carbonate, aluminum hydroxide, zinc oxide, magnesium oxide, silica, potassium titanate, calcium sulfite, calcium silicate, wax. A moisture-permeable film containing one or more selected from lastonite, talc, mica, clay, kaolinite, montmorillonite, hydrotalcite, polystyrene resin particles and poly(meth)acrylic resin particles.
[7]
In the moisture-permeable film according to any one of [1] to [6] above,
A moisture-permeable film having a water vapor transmission rate of 20 g/(m ² ·24 h) or more at 40°C and 90% RH.
[8]
In the moisture-permeable film according to any one of [1] to [7] above,
A moisture-permeable film in which the surface resin layer (B) contains a polyolefin resin.
[9]
In the moisture-permeable film according to [8] above,
A moisture-permeable film in which the polyolefin-based resin in the surface resin layer (B) contains at least one selected from polyethylene-based resins and polypropylene-based resins.
[10]
In the moisture-permeable film according to any one of [1] to [9] above,
Sanitary products, medical products, health care products, filter products, geotextile products, agricultural products, horticultural products, clothing, footwear products, luggage products, household products, industrial products, packaging products, construction products and structures A moisture-permeable film used for any one selected from the group consisting of products for
[11]
A package using the moisture-permeable film according to any one of [1] to [9] above.

ADVANTAGE OF THE INVENTION According to this invention, while being excellent in continuous film-forming property and an external appearance, the moisture-permeable film which can control moisture permeability highly can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which showed typically an example of the structure of the moisture-permeable film of embodiment which concerns on this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which showed typically an example of the structure of the moisture-permeable film of embodiment which concerns on this invention.

An embodiment of the present invention will be described below with reference to the drawings. It should be noted that the drawings are schematic diagrams and do not correspond to actual dimensional ratios. In addition, unless otherwise specified, "~" between numbers in the text represents the following from the above.

<Moisture-permeable film>
1 and 2 are cross-sectional views schematically showing an example of the structure of a moisture-permeable film 10 according to an embodiment of the invention.
The moisture-permeable film 10 according to the present embodiment includes a biaxially stretched film layer (A) containing a thermoplastic resin and at least one filler selected from organic fillers and inorganic fillers, and the biaxially stretched film layer ( and a surface resin layer (B) provided on at least one surface of A), and the total thickness of the surface resin layer (B) is 10 μm or less.

As described above, a film formed from a resin composition containing a thermoplastic resin and a filler is known as a moisture-permeable film. According to the studies of the present inventors, the moisture-permeable film formed from a resin composition containing a thermoplastic resin and a filler causes poor sticking to the chill roll and stains on the roll during continuous film formation. It has become clear that the continuous film-forming property and the appearance are inferior. Furthermore, it is difficult to highly control the moisture permeability level of a moisture permeable film formed from a resin composition containing a thermoplastic resin and a filler while maintaining basic properties such as mechanical properties.
The present inventors have made intensive studies to solve the above problems. As a result, by providing a surface resin layer (B) with a total thickness of 10 μm or less on the surface of the biaxially stretched film layer (A) containing a thermoplastic resin and a filler, continuous film formability and appearance are improved. It has been found that the moisture permeability can be highly controlled by the total thickness of the surface resin layer (B) while maintaining the moisture permeability at . In particular, in the moisture-permeable film 10 according to the present embodiment, the water vapor transmission rate and the like can be controlled stepwise by stepwise controlling the total thickness of the surface resin layer (B). Therefore, by controlling the total thickness of the surface resin layer (B), it is possible to easily obtain the moisture-permeable film 10 having a desired water vapor transmission rate.
That is, according to the present embodiment, it is possible to provide the moisture-permeable film 10 that is excellent in continuous film-forming properties and appearance, and whose moisture permeability can be highly controlled.

In the moisture-permeable film 10 according to the present embodiment, from the viewpoint of stably obtaining the moisture-permeable film 10 or the package having excellent moisture permeability, the water vapor transmission rate at 40° C. and 90% RH is measured by the following method. is preferably 20 g/(m ² ·24 h) or more, more preferably 30 g/(m ² ·24 h) or more, further preferably 50 g/(m ² ·24 h) or more, and 100 g/ (m ² ·24h) or more is particularly preferable.
(Measuring method)
The moisture-permeable film 10 according to this embodiment is folded back and heat-sealed on two sides to form a bag. After that, calcium chloride is added as the content. The other side is then heat-sealed to form a bag with a surface area of 0.01 m ² . The resulting bag is then stored for 1 hour under the conditions of 40° C. and 90% RH. The weight of calcium chloride before and after storage is measured, and the water vapor permeability (g/(m ² ·24h)) is calculated from the difference.
Such water vapor permeability is, for example, the content ratio of the filler contained in the biaxially stretched film layer (A), the thickness and draw ratio of the biaxially stretched film layer (A), the total thickness of the surface resin layer (B), and the like. can be achieved by adjusting In particular, the moisture-permeable film 10 according to the present embodiment is a biaxially stretched film layer ( Water vapor permeability can be controlled at a high level without changing the configuration of A). That is, according to the moisture-permeable film 10 according to the present embodiment, it is possible to highly control the moisture-permeable level while maintaining basic properties such as mechanical properties.

Although the thickness of the moisture-permeable film 10 according to the present embodiment is not particularly limited, it can be arbitrarily set according to desired purposes such as water vapor permeability, cost, mechanical properties, and lightness, and is not particularly limited. For example, it is 10 μm or more and 500 μm or less, preferably 15 μm or more and 400 μm or less, and more preferably 20 μm or more and 300 μm or less.
When the thickness of the moisture-permeable film is within the above range, the moisture permeability, air permeability, bag-making properties, mechanical properties, handling properties, appearance, moldability, lightness, cost, etc. are well balanced.

Each layer constituting the moisture-permeable film will be described below.

[Biaxially stretched film layer (A)]
The biaxially stretched film layer (A) according to the present embodiment is, for example, a resin composition (A) containing a thermoplastic resin and at least one filler selected from organic fillers and inorganic fillers. It is formed by biaxially stretching a stretched film layer.

The biaxially stretched film layer (A) according to the present embodiment may be a single layer, or may be a structure in which a plurality of layers composed of the resin composition (A) are laminated, but it is biaxially stretched. It is necessary.

In addition, in the moisture-permeable film 10 according to the present embodiment, the ratio of the thickness of the biaxially stretched film layer (A) to the overall thickness of the moisture-permeable film 10 is preferably 0.50 or more and 0.998 or less. It is preferably 0.60 or more and 0.99 or less, more preferably 0.70 or more and 0.98 or less, and particularly preferably 0.75 or more and 0.98 or less.

In the moisture-permeable film 10 according to this embodiment, the biaxially stretched film layer (A) preferably has air holes on its surface. Thereby, the moisture permeability and air permeability of the moisture-permeable film can be further improved. Here, the air holes are observed by electron microscopy of the surface of the moisture-permeable film after peeling the surface resin layer (B) from the surface of the biaxially stretched film layer (A) (that is, the surface of the biaxially stretched film layer (A)). can be confirmed by observing The maximum hole diameter of the ventilation holes is, for example, 5 μm or more and 50 μm or less. Here, the maximum pore diameter means the maximum pore diameter of one ventilation hole.
Such air holes can be formed, for example, by adjusting the content of the filler contained in the biaxially stretched film layer (A), the thickness of the biaxially stretched film layer (A), the stretching ratio, and the like.

(Resin composition (A))
The resin composition (A) according to this embodiment contains a thermoplastic resin and a filler.
From the viewpoint of improving the moisture permeability and air permeability of the moisture-permeable film 10, the lower limit of the content of the filler contained in the resin composition (A) according to the present embodiment, that is, the biaxially stretched film layer (A) is When the stretched film layer (A) as a whole is 100% by mass, it is preferably 40% by mass or more, more preferably 50% by mass or more, still more preferably 55% by mass or more, and particularly preferably 60% by mass. % or more.
In addition, the upper limit of the content of the filler contained in the resin composition (A) according to the present embodiment, that is, the biaxially stretched film layer (A) is determined from the viewpoint of improving the moldability and mechanical properties of the moisture-permeable film 10. Therefore, when the entire biaxially stretched film layer (A) is taken as 100% by mass, it is preferably 70% by mass or less.

The total content of the thermoplastic resin and filler contained in the resin composition (A) according to the present embodiment, that is, the biaxially stretched film layer (A), is 100% by mass of the entire resin composition (A). , preferably 50% to 100% by mass, more preferably 70% to 100% by mass, still more preferably 90% to 100% by mass, particularly preferably 95% to 100% by mass. As a result, the moisture permeability, air permeability, mechanical properties, handleability, appearance, moldability, etc. can be well balanced.

(Thermoplastic resin)
The thermoplastic resin used for the biaxially stretched film layer (A) is not particularly limited, but examples include polyolefin resins, polymethacrylic resins such as polymethyl methacrylate resins, and polyacrylic resins such as polymethyl acrylate resins. , polystyrene resin, polyvinyl acetal resin, polyvinyl butyral resin, polyvinyl formal resin, polymethylpentene resin, polycarbonate resin, polyether ether ketone resin, polyether ketone resin, polyester resin, polyamide resin, polyamide Imide resin, polyimide resin, polyetherimide resin, styrene elastomer, polyolefin elastomer, polyurethane elastomer, polyester elastomer, polyamide elastomer, norbornene resin, polytetrafluoroethylene resin, ethylenetetrafluoroethylene copolymer, polyvinylidene fluoride resin , polyvinyl fluoride resin, thermoplastic polyimide resin, polyvinylidene chloride resin, polyvinyl chloride resin, polyvinyl acetate resin, polysulfone resin, polyphenylene resin such as polyphenylene oxide resin and polyphenylene sulfide resin, polysulfone resin, polylactic acid resin, poly Ethersulfone resins, polyacrylonitrile resins, styrene-acrylonitrile copolymer resins, and the like can be mentioned.
Among these, polyolefin-based resins are preferable from the viewpoint of excellent balance of moisture permeability, air permeability, mechanical properties, handleability, appearance, light weight, price, moldability, and the like. These thermoplastic resins may be used singly or in combination of two or more.

(polyolefin resin)
Polyolefin resins used in the biaxially stretched film layer (A) include, for example, single weights of α-olefins such as ethylene, propylene, butene-1, hexene-1, 4-methyl-pentene-1, and octene-1. Coalescing or copolymer; high-pressure low-density polyethylene; linear low-density polyethylene (LLDPE); high-density polyethylene; polypropylene; random copolymer of propylene and α-olefin having 2 to 10 carbon atoms; vinyl copolymer (EVA); ionomer resin, and the like. These polyolefin-based resins may be used singly or in combination of two or more.
Among these, at least one selected from polyethylene-based resins and polypropylene-based resins is preferable, and polypropylene-based resins are more preferable.

(polyethylene resin)
Examples of the polyethylene-based resin used for the biaxially stretched film layer (A) include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and ultra-high molecular weight polyethylene. Among these, low-density polyethylene and linear low-density polyethylene are preferred, and linear low-density polyethylene is more preferred. One type of polyethylene may be used, or two or more types may be used in combination.

The melting point of the polyethylene resin according to the present embodiment is preferably 95° C. or higher and 135° C. or lower, more preferably 95° C. or higher and 135° C. or lower, from the viewpoint of further improving the balance of heat resistance, mechanical properties, rigidity, fluidity, moldability, etc. It is in the range of 100°C or higher and 130°C or lower.

Based on ASTM D1238, the melt flow rate (MFR) of the polyethylene resin according to the present embodiment measured under conditions of 190° C. and a load of 2.16 kg is preferably 0.5 g from the viewpoint of fluidity and moldability. /10 min or more, more preferably 1 g/10 min or more, still more preferably 2 g/10 min or more, and from the viewpoint of further stabilizing moldability, preferably 30 g/10 min or less, more preferably 20 g/10 min. Below, more preferably 10 g/10 minutes or less.

The method for producing the polyethylene-based resin according to this embodiment is not particularly limited, and it can be produced by a known method. A commercially available polyethylene resin may also be used.

(polypropylene resin)
Examples of the polypropylene resin used for the biaxially oriented film layer (A) include homopolypropylene, copolymers of propylene and ethylene or α-olefins having 4 to 20 carbon atoms, and the like. Examples of the α-olefins having 4 to 20 carbon atoms include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene and the like. Among these, ethylene or an α-olefin having 4 to 10 carbon atoms is preferred, and ethylene is more preferred. These α-olefins may form random copolymers or block copolymers with propylene. The content of structural units derived from ethylene or an α-olefin having 4 to 20 carbon atoms is preferably 5 mol% or less, preferably 2 mol% or less, when the entire polypropylene resin is 100 mol%. It is more preferable to have The polypropylene resin in the biaxially stretched film layer (A) may be used singly or in combination of two or more.
Among these, from the viewpoint of obtaining a biaxially stretched film layer (A) with a more excellent balance of performance such as heat resistance, moldability, mechanical properties and rigidity, the polypropylene-based resins include homopolypropylene and propylene and ethylene or carbon number is preferably at least one selected from random copolymers with α-olefins having a molecular weight of 4 to 10 (hereinafter also referred to as propylene/α-olefin random copolymers).
In the homopolypropylene according to the present embodiment, the content of structural units derived from propylene is 99.0 mol% or more, preferably 99.0 mol%, when the total content of the structural units constituting the homopolypropylene is 100 mol%. It is 5 mol % or more, more preferably 99.9 mol % or more, and particularly preferably 100.0 mol %.

The propylene/α-olefin random copolymer according to the present embodiment is a random copolymer of propylene and ethylene or an α-olefin having 4 to 10 carbon atoms. -butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene and the like. These copolymers may be used alone, or two or more of them may be mixed and used.
Among the propylene/α-olefin random copolymers, propylene/ethylene random copolymers, propylene/ethylene/1-butene random copolymers, and propylene/1-butene random copolymers are preferred.

The polypropylene-based resin according to this embodiment can be produced by various methods. For example, it can be produced using known catalysts such as Ziegler-Natta catalysts and metallocene catalysts.

The melting point of the polypropylene-based resin according to the present embodiment is preferably 90° C. or higher and 175° C. or lower, more preferably 90° C. or higher and 175° C. or lower, from the viewpoint of further improving the balance of heat resistance, mechanical properties, rigidity, fluidity, moldability, etc. It is in the range of 95° C. or higher and 170° C. or lower, more preferably 100° C. or higher and 167° C. or lower.

The melt flow rate (MFR) of the polypropylene-based resin according to the present embodiment, which is measured under conditions of 230° C. and a load of 2.16 kg according to ASTM D1238, is preferably 0.5 g from the viewpoint of fluidity and moldability. /10 min or more, more preferably 1 g/10 min or more, still more preferably 2 g/10 min or more, and from the viewpoint of further stabilizing moldability, preferably 20 g/10 min or less, more preferably 10 g/10 min. 7 g/10 minutes or less, more preferably 7 g/10 minutes or less.

(filler)
The biaxially stretched film layer (A) according to this embodiment contains at least one filler selected from organic fillers and inorganic fillers as an essential component.
Examples of fillers used in the biaxially stretched film layer (A) include calcium carbonate, calcium sulfate, barium carbonate, barium sulfate, titanium oxide, magnesium hydroxide, magnesium carbonate, aluminum hydroxide, zinc oxide, magnesium oxide and silica. , potassium titanate, calcium sulfite, calcium silicate, wollastonite, talc, mica, clay, kaolinite, montmorillonite, hydrotalcite, and other inorganic fillers; polystyrene resin particles, poly(meth)acrylic resin particles, etc. An organic filler etc. are mentioned. These fillers may be used individually by 1 type, and may be used in combination of 2 or more types. Among these, calcium carbonate is preferable because it is inexpensive and can further improve the moisture permeability of the moisture-permeable film.

In addition, the filler may be used as it is without treatment, and in order to improve the interfacial adhesion with the thermoplastic resin and improve the dispersibility in the thermoplastic resin, a silane coupling agent, a titanium coupling agent, an interfacial The surface may be treated with an activator or the like before use.

(other ingredients)
The resin composition (A) according to the present embodiment may optionally contain a tackifier, a heat stabilizer, a weather stabilizer, an antioxidant, an ultraviolet absorber, a lubricant, a slip agent, a nucleating agent, and an antiblocking agent. , antistatic agents, antifogging agents, pigments, dyes, and other additives may be added within a range that does not impair the purpose of the present embodiment.

(Method for preparing resin composition (A))
The resin composition (A) according to the present embodiment, for example, dry blend each component, tumbler mixer, Banbury mixer, single screw extruder, twin screw extruder, high speed twin screw extruder, hot rolls, etc. mixed or melted • Can be prepared by kneading.

[Surface resin layer (B)]
The moisture-permeable film 10 according to the present embodiment suppresses poor sticking to the molding machine, roll contamination, etc., and improves continuous film-forming properties. A surface resin layer (B) is provided thereon. From the viewpoint of suppressing poor sticking to the molding machine and improving continuous film-forming properties, the surface resin layer (B) is preferably provided on both sides of the biaxially stretched film layer (A). .
In addition, the surface resin layer (B) is provided as the outermost layer of the moisture-permeable film 10 from the viewpoint of further suppressing poor adhesion to the molding machine, roll contamination, etc., and improving continuous film-forming properties. is preferred.

Moreover, the surface resin layer (B) is preferably provided so as to be in direct contact with the surface of the biaxially stretched film layer (A). Thereby, the manufacturing process of the moisture-permeable film 10 can be simplified.

In the moisture-permeable film 10 according to this embodiment, the thickness of the surface resin layer (B) is preferably 5.0 μm or less, more preferably 3.0 μm or less, even more preferably 2.5 μm or less, and even more preferably 1.0 μm or less. 5 μm or less, particularly preferably 0.6 μm or less.
In addition, in the moisture-permeable film 10 according to the present embodiment, the total thickness of the surface resin layer (B) is 10 µm or less, preferably 6.0 µm or less, more preferably 5.0 µm or less, and still more preferably 3.0 µm. Below, it is particularly preferably 1.2 μm or less.
Here, the thickness of the surface resin layer (B) is the thickness of the surface resin layer (B) provided on one side of the biaxially stretched film layer (A), and the total thickness of the surface resin layer (B) is two It refers to the total thickness of all the surface resin layers (B) provided on the axially stretched film layer (A).
Moreover, when the thickness or the total thickness of the surface resin layer (B) is equal to or less than the above upper limit value, the moisture permeability and air permeability of the moisture-permeable film 10 can be further improved.
In addition, since the thickness of the surface resin layer (B) is equal to or less than the above upper limit, the adhesion between the biaxially stretched film layer (A) and the surface resin layer (B) is improved, and the biaxially stretched film layer (A ) to form the surface resin layer (B) thereon. That is, since it becomes easy to provide the surface resin layer (B) so as to be in direct contact with the surface of the biaxially stretched film layer (A), the manufacturing process of the moisture-permeable film 10 can be simplified.

In the moisture-permeable film 10 according to this embodiment, the surface resin layer (B) preferably has a thickness of 0.01 μm or more, more preferably 0.05 μm or more, and even more preferably 0.1 μm or more.
In addition, in the moisture-permeable film 10 according to this embodiment, the total thickness of the surface resin layer (B) is 0.02 μm or more, more preferably 0.1 μm or more, and still more preferably 0.2 μm or more.
When the thickness or the total thickness of the surface resin layer (B) is at least the above lower limit, poor sticking to the molding machine, roll contamination, etc. can be further suppressed, and continuous film-forming properties can be improved.

In the moisture-permeable film 10 according to this embodiment, the surface resin layer (B) provided on one surface is preferably a single layer. Thereby, the manufacturing process of the moisture-permeable film 10 can be further simplified.

Moreover, it is preferable that the surface resin layer (B) is formed by stretching simultaneously with the film in a state before stretching of the biaxially stretched film layer (A). As a result, the moisture-permeable film 10 can be produced using a molding method such as a co-extrusion molding method, that is, the laminated film produced by one-time molding, thereby further simplifying the manufacturing process of the moisture-permeable film 10. can be done. Therefore, the surface resin layer (B) is preferably stretched.

The surface resin layer (B) according to this embodiment can be formed, for example, by biaxially stretching an unstretched film layer composed of the resin composition (B) containing a thermoplastic resin.

(Resin composition (B))
The resin composition (B) according to this embodiment contains a thermoplastic resin.
The content of the thermoplastic resin contained in the resin composition (B) according to the present embodiment, that is, the surface resin layer (B) is preferably 60% by mass when the entire resin composition (B) is taken as 100% by mass. 100% by mass or less, more preferably 70% by mass or more and 100% by mass or less, still more preferably 80% by mass or more and 100% by mass or less, even more preferably 90% by mass or more and 100% by mass or less, particularly preferably 95% by mass or more It is 100% by mass or less. As a result, poor sticking to the molding machine and the like can be further suppressed, and continuous film-forming properties can be improved.

(Thermoplastic resin)
The thermoplastic resin used for the surface resin layer (B) is not particularly limited, but examples include polyolefin resins, polymethacrylic resins such as polymethyl methacrylate resins, polyacrylic resins such as polymethyl acrylate resins, and polystyrene. Resin, polyvinyl acetal resin, polyvinyl butyral resin, polyvinyl formal resin, polymethylpentene resin, polycarbonate resin, polyether ether ketone resin, polyether resin such as polyether ketone resin, polyester resin, polyamide resin, polyamideimide resin , polyimide resin, polyetherimide resin, styrene elastomer, polyolefin elastomer, polyurethane elastomer, polyester elastomer, polyamide elastomer, norbornene resin, polytetrafluoroethylene resin, ethylenetetrafluoroethylene copolymer, polyvinylidene fluoride resin, polyfluoride resin Polyphenylene resins such as vinyl chloride resin, thermoplastic polyimide resin, polyvinylidene chloride resin, polyvinyl chloride resin, polyvinyl acetate resin, polysulfone resin, polyphenylene oxide resin and polyphenylene sulfide resin, polysulfone resin, polylactic acid resin, polyether sulfone resins, polyacrylonitrile resins, styrene-acrylonitrile copolymer resins, and the like.
Among these, polyolefin resins are preferable from the viewpoint of excellent balance among mechanical properties, handleability, appearance, light weight, price, moldability, and the like. These thermoplastic resins may be used singly or in combination of two or more.

(polyolefin resin)
Examples of the polyolefin resin used for the surface resin layer (B) include homopolymers of α-olefins such as ethylene, propylene, butene-1, hexene-1, 4-methyl-pentene-1, and octene-1, or Copolymer; high-pressure low-density polyethylene; linear low-density polyethylene (LLDPE); high-density polyethylene; polypropylene; random copolymer of propylene and α-olefin having 2 to 10 carbon atoms; polymer (EVA); ionomer resin and the like. These polyolefin-based resins may be used singly or in combination of two or more.
Among these, at least one selected from polyethylene-based resins and polypropylene-based resins is preferable, and polypropylene-based resins are more preferable.

(polyethylene resin)
Examples of the polyethylene-based resin used for the surface resin layer (B) include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and ultra-high molecular weight polyethylene. Among these, low-density polyethylene and linear low-density polyethylene are preferred, and linear low-density polyethylene is more preferred. One type of polyethylene may be used, or two or more types may be used in combination.

The melting point of the polyethylene resin according to the present embodiment is preferably 95° C. or higher and 135° C. or lower, more preferably 95° C. or higher and 135° C. or lower, from the viewpoint of further improving the balance of heat resistance, mechanical properties, rigidity, fluidity, moldability, etc. It is in the range of 100°C or higher and 130°C or lower.

Based on ASTM D1238, the melt flow rate (MFR) of the polyethylene resin according to the present embodiment measured under conditions of 190° C. and a load of 2.16 kg is preferably 0.5 g from the viewpoint of fluidity and moldability. /10 min or more, more preferably 1 g/10 min or more, still more preferably 2 g/10 min or more, and from the viewpoint of further stabilizing moldability, preferably 30 g/10 min or less, more preferably 20 g/10 min. Below, more preferably 10 g/10 minutes or less.

The method for producing the polyethylene-based resin according to this embodiment is not particularly limited, and it can be produced by a known method. A commercially available polyethylene resin may also be used.

(polypropylene resin)
Examples of the polypropylene-based resin according to the present embodiment include homopolypropylene, a copolymer of propylene and ethylene or an α-olefin having 4 to 20 carbon atoms, and the like. Examples of the α-olefins having 4 to 20 carbon atoms include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene and the like. Among these, ethylene or an α-olefin having 4 to 10 carbon atoms is preferred, and ethylene is more preferred. These α-olefins may form random copolymers or block copolymers with propylene. The content of structural units derived from ethylene or an α-olefin having 4 to 20 carbon atoms is preferably 5 mol% or less, preferably 2 mol% or less, when the entire polypropylene resin is 100 mol%. It is more preferable to have The polypropylene resin in the surface resin layer (B) may be used singly or in combination of two or more.
Among these, from the viewpoint of obtaining a surface resin layer (B) with a more excellent performance balance such as heat resistance, moldability, mechanical properties and rigidity, the polypropylene-based resins include homopolypropylene, propylene and ethylene, or those having 4 carbon atoms. At least one selected from random copolymers with α-olefins of 1 to 10 (hereinafter also referred to as propylene/α-olefin random copolymers) is preferred.
In the homopolypropylene according to the present embodiment, the content of structural units derived from propylene is 99.0 mol% or more, preferably 99.0 mol%, when the total content of the structural units constituting the homopolypropylene is 100 mol%. It is 5 mol % or more, more preferably 99.9 mol % or more, and particularly preferably 100.0 mol %.

The propylene/α-olefin random copolymer according to the present embodiment is a random copolymer of propylene and ethylene or an α-olefin having 4 to 10 carbon atoms. -butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene and the like. These copolymers may be used alone, or two or more of them may be mixed and used.
Among the propylene/α-olefin random copolymers, propylene/ethylene random copolymers, propylene/ethylene/1-butene random copolymers, and propylene/1-butene random copolymers are preferred.

The polypropylene-based resin according to this embodiment can be produced by various methods. For example, it can be produced using known catalysts such as Ziegler-Natta catalysts and metallocene catalysts.

The melting point of the polypropylene-based resin according to the present embodiment is preferably 90° C. or higher and 175° C. or lower, more preferably 90° C. or higher and 175° C. or lower, from the viewpoint of further improving the balance of heat resistance, mechanical properties, rigidity, fluidity, moldability, etc. It is in the range of 95° C. or higher and 170° C. or lower, more preferably 100° C. or higher and 167° C. or lower.

The melt flow rate (MFR) of the polypropylene-based resin according to the present embodiment, which is measured under conditions of 230° C. and a load of 2.16 kg according to ASTM D1238, is preferably 0.5 g from the viewpoint of fluidity and moldability. /10 min or more, more preferably 1 g/10 min or more, still more preferably 2 g/10 min or more, and from the viewpoint of further stabilizing moldability, preferably 20 g/10 min or less, more preferably 10 g/10 min. 7 g/10 minutes or less, more preferably 7 g/10 minutes or less.

(other ingredients)
The resin composition (B) according to the present embodiment may optionally contain a filler, a tackifier, a heat stabilizer, a weather stabilizer, an antioxidant, an ultraviolet absorber, a lubricant, a slip agent, a nucleating agent, an anti Various additives such as blocking agents, antistatic agents, antifogging agents, pigments, and dyes may be added as long as the objects of the present embodiment are not impaired.

<Method for manufacturing moisture-permeable film>
The moisture-permeable film 10 according to the present embodiment includes, for example, a resin composition (A) for forming a biaxially stretched film layer (A) and a resin composition (B) for forming a surface resin layer (B ) and are co-extruded into a film, and then biaxially stretched using a known stretching method.
The molding apparatus and molding conditions are not particularly limited, and conventionally known molding apparatuses and molding conditions can be employed. A multi-layer T-die extruder, a multi-layer inflation molding machine, or the like can be used as a molding device. The stretching conditions are not particularly limited because they are appropriately adjusted depending on the content ratio and combination of the thermoplastic resin and the filler. For example, various known conditions for producing biaxially stretched films can be employed.

<Application of Moisture Permeable Film>
The moisture-permeable film 10 according to this embodiment is excellent in moisture permeability and air permeability, and is also excellent in water resistance and mechanical properties. Therefore, it can be suitably used for applications requiring moisture permeability, air permeability, water resistance, and mechanical properties. Such applications include, for example, packaging products such as foods and pharmaceuticals, desiccants, oxygen scavengers, alcohol volatilization agents, and freshness-preserving agents; sanitary products such as backsheets for disposable diapers and backsheets for sanitary products; medical products; Healthcare products, filter products, geotextile products, agricultural products, gardening products, clothes such as simple jumpers, footwear products, bag products, household products, industrial products, construction products such as waterproof and breathable sheets for building materials, or Structural products and the like are preferred.

In addition, the moisture-permeable film according to the present embodiment may use the moisture-permeable film 10 according to the present embodiment as a part of the film according to the application, or the moisture-permeable film 10 according to the present embodiment may be used for the entire use article. You may use the moisture-permeable film 10 which concerns on.
Packaging products include, for example, food and pharmaceuticals, alcohol volatilization agents, freshness-preserving agent packaging, desiccant packaging, dehumidifying agent packaging, adsorbent packaging such as oxygen absorbers, gift boxes, file boxes, and non-woven bags. , book covers, envelopes, express envelopes, delivery bags, etc.
Construction and structural products include, for example, house wraps, asphalt overlays, road and railway subgrades, golf courts, tennis courts, wall covering linings, acoustic wall coverings, roofing materials, tile underlays, soils Stabilizers, road underlays, foundation stabilizers, erosion control products, canal construction, drainage systems, geomembrane protection products, frost protection products, agricultural mulch, pond and canal barriers, sand barriers for culvert drainage, etc. is mentioned.
Hygiene products include, for example, absorbent hygiene products (e.g. baby diapers, nappies, feminine hygiene products, adult incontinence products), depilatory strips, bandages, wound dressings, fragrance volatile parts of fragrance containers, disposable body warmers. , Disposable Bath Towels, Face Towels, Disposable Slippers, Footwear, Topsheets, Coverstocks, Consumer Face Masks, Leg Cuffs, Collection/Distribution Layers, Core Wraps, Backsheets, Elastic Ears, Implantation Zones, Dusting Layers and Fixation Systems, wipes (eg, wet wipes, skin care wipes, baby wipes, facial wipes, cleansing wipes, hand and body wipes, moist towels, personal hygiene wipes, feminine hygiene wipes, antibacterial wipes, medical wipes), and the like.
Medical and healthcare products include, for example, sterilizable medical products, medical packaging, caps (e.g. surgical disposable caps), protective garments, surgical gowns, surgical masks, surgical face masks, surgical gowns, surgical surgical covers, surgical drapes, wraps, packs, sponges, bandages, wipes, bed linen, contamination control gowns, examination gowns, laboratory coats, isolation gowns, transdermal drug delivery, shrouds, underpads, procedure packs, Heat packs, ostomy bag liners, fixation tapes, incubator mattresses, sterile wraps, wound care, cold/heat packs, drug delivery systems (eg, patches, etc.), and the like.
For clothing, footwear and luggage, for example, interlinings (e.g. protective clothing, overcoat fronts, collars, facings, waistbands, undercollars, etc.), disposable underwear, shoe components (e.g. shoelace eyelet reinforcement, athletic shoes, sandal reinforcements, inner sole linings, etc.), binders, compositions, (washing) caution labels, and the like.

Moreover, the moisture-permeable film according to this embodiment can also be suitably used as a film constituting a package. The packaging body according to the present embodiment is, for example, a packaging bag itself used for the purpose of containing food, pharmaceuticals, desiccants, oxygen absorbers, alcohol volatilization agents, freshness preserving agents, etc. It contains In addition, depending on the application, the package according to the present embodiment may use the moisture-permeable film 10 according to the present embodiment for a part of the package, or the moisture-permeable film 10 according to the present embodiment may be used for the entire package. You may

Although the embodiments of the present invention have been described above with reference to the drawings, these are examples of the present invention, and various configurations other than those described above can also be adopted.

Hereinafter, the present embodiment will be described in detail with reference to examples and comparative examples. It should be noted that the present embodiment is not limited to the description of these examples.

1. Raw Materials Raw materials used in Examples and Comparative Examples are shown below.
(1) Polypropylene resin PP1: homopolypropylene (MFR: 3 g/10 minutes, melting point: 165°C, manufactured by Prime Polymer Co., Ltd.)
(2) Filler-containing masterbatch MB1: Masterbatch containing calcium carbonate and homopolypropylene (content of calcium carbonate: 80% by mass, content of homopolypropylene: 20% by mass, average particle size of calcium carbonate: 4.5 µm)

2. Measurement and evaluation method (1) MFR of polypropylene resin
It was measured under conditions of 230° C. and a load of 2.16 kg according to ASTM D1238.

(2) Melting point of polypropylene-based resin The temperature of the maximum melting peak of the DSC curve of polypropylene obtained using a DSC (differential scanning calorimeter) was taken as the melting point.

(3) Presence or Absence of Ventilation Holes The surface of the moisture-permeable film after peeling of the surface resin layer (B) (that is, the surface of the biaxially stretched film layer (A)) was observed with an electron microscope to examine the presence or absence of ventilation holes. Here, vent holes having a maximum pore diameter of 5 μm or more and 50 μm or less were used.

(4) Evaluation of continuous film formability Continuous film formability of the moisture-permeable film was evaluated according to the following criteria.
○: Good continuous film formation without poor sticking to the chill roll or contamination of the roll during continuous film formation ×: Poor sticking to the chill roll during continuous film formation, Impossible to form a film and/or continuous film formation is impossible due to roll contamination during continuous film formation.

(5) Evaluation of Appearance The continuous film-forming property of the moisture-permeable film was evaluated according to the following criteria.
◯: No scum is observed on the surface.
×: May scum observed on the surface

(6) Evaluation of Moisture Permeability The moisture-permeable films obtained in Examples and Comparative Examples were folded back and heat-sealed on two sides to form a bag. After that, calcium chloride was added as the content. Then, the other side was heat-sealed to prepare a bag having a surface area of 0.01 m ² . The resulting bag was then stored for 1 hour under conditions of 40° C. and 90% RH. The weight of calcium chloride before and after storage was measured, and the water vapor permeability (g/(m ² ·24h)) was calculated from the difference.
Then, the moisture permeability of the moisture-permeable film was evaluated according to the following criteria.
○: Water vapor permeability is 20 g / (m ² · 24 h) or more ×: Water vapor permeability is less than 20 g / (m ² · 24 h) In addition, for those with continuous film forming properties of “×”, evaluation of moisture permeability has not been done.

[Examples 1 to 6 and Comparative Examples 1 to 3]
Non-stretched films were obtained by extruding each layer with the compounding ratio and layer structure shown in Table 1. Then, the obtained unstretched film was biaxially stretched to prepare a moisture-permeable film, and each evaluation was performed. Extrusion molding conditions and biaxial stretching conditions are as follows. Here, the surface resin layer (B) formed on one side of the biaxially stretched film layer (A) is called a surface resin layer 1, and the surface resin layer (B) formed on the other side is a surface resin layer. Call it 2.
Multi-layer extruder: 60 mmφ multi-layer T-die extruder (L/D = 27, manufactured by Screw Seiki Co., Ltd.)
Extrusion set temperature: 200-250°C
Processing speed: 4.0m/min
Longitudinal stretching temperature: 120-145°C
Longitudinal draw ratio: 5.0 times Lateral draw temperature: 160-180°C
Lateral draw ratio: 10.0 The obtained results are shown in Table 1. In addition, the thickness was not measured for those with a continuous film-forming property of "x".

The moisture-permeable films of Examples were excellent in moisture-permeability, continuous film-forming property and appearance, and the moisture-permeability could be highly controlled by the total thickness of the surface resin layer (B). On the other hand, the moisture-permeable films of Comparative Examples were inferior in balance between moisture permeability and continuous film-forming properties.

10 moisture-permeable film A biaxially stretched film layer B surface resin layer

Claims (10)

a biaxially stretched film layer (A) containing a thermoplastic resin and at least one filler selected from organic fillers and inorganic fillers;
A surface resin layer (B) provided on at least one surface of the biaxially stretched film layer (A),
The total thickness of the surface resin layer (B) is 10 μm or less ,
Moisture permeability , wherein the content of the filler in the biaxially stretched film layer (A) is 40% by mass or more and 70% by mass or less when the entire biaxially stretched film layer (A) is taken as 100% by mass. the film. However, those that form cracks in the surface resin layer (B) are excluded. In the moisture-permeable film according to claim 1 ,
A moisture-permeable film in which the thermoplastic resin contains a polyolefin resin. In the moisture-permeable film according to claim 2 ,
A moisture-permeable film, wherein the polyolefin-based resin contains at least one selected from polyethylene-based resins and polypropylene-based resins. In the moisture-permeable film according to any one of claims 1 to 3 ,
The biaxially stretched film layer (A) is a moisture-permeable film having air holes on its surface. In the moisture-permeable film according to any one of claims 1 to 4 ,
The filler is calcium carbonate, calcium sulfate, barium carbonate, barium sulfate, titanium oxide, magnesium hydroxide, magnesium carbonate, aluminum hydroxide, zinc oxide, magnesium oxide, silica, potassium titanate, calcium sulfite, calcium silicate, wax. A moisture-permeable film containing one or more selected from lastonite, talc, mica, clay, kaolinite, montmorillonite, hydrotalcite, polystyrene resin particles and poly(meth)acrylic resin particles. In the moisture-permeable film according to any one of claims 1 to 5 ,
A moisture-permeable film having a water vapor transmission rate of 20 g/(m ² ·24 h) or more at 40°C and 90% RH. In the moisture-permeable film according to any one of claims 1 to 6 ,
A moisture-permeable film in which the surface resin layer (B) contains a polyolefin resin. In the moisture-permeable film according to claim 7 ,
A moisture-permeable film in which the polyolefin-based resin in the surface resin layer (B) contains at least one selected from polyethylene-based resins and polypropylene-based resins. In the moisture-permeable film according to any one of claims 1 to 8 ,
Sanitary products, medical products, health care products, filter products, geotextile products, agricultural products, horticultural products, clothing, footwear products, luggage products, household products, industrial products, packaging products, construction products and structures A moisture-permeable film used for any one selected from the group consisting of products for A package using the moisture-permeable film according to any one of claims 1 to 8 .

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