JP2017165849A - Polyolefin-based porous film excellent in touch feeling and designability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyolefin-based porous film which can achieve not only air permeability but also excellent glossiness and touch feeling.SOLUTION: There are provided a film which has 20-80 mass% of a polyolefin-based film and 20-80 mass% of an inorganic filler, where the film is stretched at least in one direction and has 60° glossiness of 3.0 or more; and a polyolefin-based porous film which has stretching magnification of 1.0-8.0 times in a transverse direction of the film and/or stretching magnification of 1.0-8.0 times in a longitudinal direction, where the stretching magnification in the transverse direction is larger than the stretching magnification in the longitudinal direction, and a product of the stretching magnification in the transverse direction and the stretching magnification in the longitudinal direction is preferably 3.0 or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a polyolefin-based porous film. In particular, the present invention relates to a polyolefin-based porous film excellent in touch and design (glossiness) and a method for producing the same.

  Conventionally, a polyolefin-based porous film has a liquid-proof moisture permeability that blocks a liquid such as water droplets while allowing a gas such as air and water vapor to pass therethrough, such as a paper diaper, a paper pant, and a sanitary napkin. It is widely used as a liquid-proof and moisture-permeable film for sanitary materials, medical materials, packaging materials, special building materials and the like.

  Since sanitary products and medical materials, especially paper diapers, paper pants and sanitary napkins, poultices, bandages, etc., are in direct contact with the skin for a long time, films having excellent tactile properties are desired. In addition, from the viewpoint of improving the standard of living and the intended use of sanitary goods, a film with added design, luxury, concealment and the like has been proposed. Moreover, in the sanitary goods, since it adheres to the skin and stuffiness, covering, etc. occur, it is basically necessary that the film has excellent breathability and moisture permeability.

  Conventionally, according to Patent Document 1 (Japanese Patent Laid-Open No. 2002-128929) and Patent Document 2 (Japanese Patent Laid-Open No. 2003-012842), an inorganic filler is added to a polyolefin-based resin and an unstretched sheet is formed. A porous film obtained by applying a predetermined preparation has been proposed.

  Patent Document 3 (Japanese Patent Laid-Open No. 2001-294695) proposes a polyolefin film in which a polyolefin composition in which inorganic filler particles are dispersed is stretched to be porous. Furthermore, in patent document 4 (Unexamined-Japanese-Patent No. 2000-136254), in the polyolefin film of patent document 3, the total light transmittance (transmittance) can be improved and filths, such as underpants, can be visually recognized easily. A film has been proposed. Furthermore, what added colorants, such as a pigment and dye, to the resin component is proposed (Unexamined-Japanese-Patent No. 2015-229722).

Certainly, the above prior art provides a polyolefin porous film having excellent performance such as air permeability and moisture permeability.
However, the polyolefin films proposed in the above prior arts improve air permeability and total permeability, but most of them are not preferable in terms of touch and design when used as substrates and fibers. It was.

  For sanitary goods, it may be preferable to use base materials and fibers that can conceal filth according to the intended use, and for clothing, the body should be transparent. In general, it is preferable to use a porous polyolefin film having a concealing property (shielding property). Furthermore, in the current situation of highly personalized and differentiated modern products, consumers are interested in product design, and in particular in hygiene products, the design of products depends on the interest at the time of purchase and use. It has become.

  Therefore, there is still a demand for the development of a polyolefin film capable of realizing excellent tactile sensation and design (glossiness) while improving the basic performance of air permeability and permeability.

JP 2002-128929 A JP 2003-012842 A JP 2001-294695 A JP 2000-136254 A JP2015-229722A

At the time of the present invention, the present inventors made the polyolefin resin and the inorganic filler a specific mixing ratio, and adjusted the 60 ° gloss while taking into account the stretch ratio of the film, thereby providing excellent tactile sensation. In addition, the inventors have obtained knowledge that a polyolefin film having glossiness, high air permeability, moisture permeability, and high-class feeling can be obtained.
Therefore, the present invention has been made based on such knowledge.

[First embodiment]
Therefore, the first aspect is a polyolefin-based porous film,
20% by mass or more and 80% by mass or less polyolefin-based resin;
Comprising 20% by mass or more and 80% by mass or less of an inorganic filler,
The film is stretched in at least a uniaxial direction,
A film having a 60 ° gloss of 3.0 or more can be proposed.

[Second embodiment]
A second aspect is a method for producing a polyolefin-based porous film,
Preparing a composition comprising a polyolefin-based resin of 20% by mass to 80% by mass and an inorganic filler of 20% by mass to 80% by mass;
Forming the composition into a film;
Stretching the film at least in a uniaxial direction;
A method for producing a polyolefin-based porous film having a 60 ° gloss of 3.0 or more can be proposed.

  Therefore, according to the present invention, it has excellent tactile sensation and design (glossiness), and has high breathability, moisture permeability and shielding properties, high quality, mechanical structure stability, molding stability, and ease of production. A polyolefin-based porous film and a method for producing the same can be provided.

The embodiment according to the present invention is as follows.
[1] A polyolefin-based porous film,
20% by mass or more and 80% by mass or less polyolefin-based resin;
Comprising 20% by mass or more and 80% by mass or less of an inorganic filler,
The film is stretched in at least a uniaxial direction,
A film having a 60 ° gloss of 3.0 or more.
[2] The film according to [1], wherein the stretching is performed in a transverse direction of the film.
[3] The film according to [1 or 2], wherein a stretching ratio in a transverse direction of the film is 1.0 to 8.0.
[4] The film according to any one of [1] to [3], wherein the stretching is performed in a longitudinal direction of the film.
[5] The film according to [4], wherein a stretching ratio in the longitudinal direction of the film is 1.0 or more and 8.0 or less.
[6] The film according to [4] or [5], wherein a stretching ratio in the transverse direction of the film is larger than a stretching ratio in the longitudinal direction of the film.
[7] The film according to [4] or [5], wherein a product of a stretching ratio in the transverse direction of the film and a stretching ratio in the longitudinal direction of the film is 3.0 or more.
[8] The film has a thickness of 5 μm to 100 μm,
The film according to any one of [1] to [7], wherein the density of the film is 1.5 g / cm ³ or less.
[9] A white standard plate is overlaid on one side of the film, and L ₁ ^* , a ₁ ^* , b ₁ ^* of the other side of the film without the white standard plate is measured, and the film A color standard ΔE calculated by the following formula (formula 1) is obtained by measuring the L ₂ ^* a ₂ ^* b ₂ ^* of the other side where the black standard plate is superimposed on one side of The film according to any one of [1] to [8], which is less than 20.
ΔE = {(L ₁ ^* −L ₂ ^* ) ² + (a ₁ ^* −a ₂ ^* ) ² + (b ₁ ^* −b ₂ ^* ) ² } ^1/2
(Formula 1)
[10] A method for producing a polyolefin-based porous film,
20% by mass or more and 80% by mass or less polyolefin-based resin;
Preparing a composition comprising 20% by mass or more and 80% by mass or less of an inorganic filler;
Forming the composition into a film;
Stretching the film at least in a uniaxial direction;
A manufacturing method in which the 60 ° glossiness is 3.0 or more.
[11] The production method according to [10], wherein the stretching is performed in a transverse direction of the film.
[12] The production method according to [11] or [12], wherein a stretching ratio in the transverse direction of the film is 1.0 to 8.0.
[13] The production method according to any one of [10] to [12], wherein the stretching is performed in a longitudinal direction of the film.
[14] The production method according to [13], wherein a draw ratio in a longitudinal direction of the film is 1.0 or more and 8.0 or less.
[15] The production method according to [14] or [15], wherein the stretching ratio in the transverse direction of the film is larger than the stretching ratio in the longitudinal direction of the film.
[16] The production method according to [14] or [15], wherein a product of a stretching ratio in the transverse direction of the film and a stretching ratio in the longitudinal direction of the film is 3.0 or more.
[17] The thickness of the film is 5 μm or more and 100 μm or less,
The production method according to any one of [11] to [16], wherein the density of the film is 1.5 g / cm ³ or less.
[18] A white standard plate is overlaid on one side of the film, and L ₁ ^* , a ₁ ^* , b ₁ ^* of the other side of the film without the white standard plate is measured, and the film A black standard plate is overlaid on one side of the film, and L ₂ ^* a ₂ ^* b ₂ ^* is measured on the other side of the film on which the black standard plate is not overlaid, and is calculated by the following formula (formula 1). The production method according to any one of [10] to [17], wherein the color difference ΔE is less than 20.
ΔE = {(L ₁ ^* −L ₂ ^* ) ² + (a ₁ ^* −a ₂ ^* ) ² + (b ₁ ^* −b ₂ ^* ) ² } ^1/2
(Formula 1)

[Polyolefinic porous film]
(Characteristic)
The concept of the polyolefin-based porous film according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing a film formed by extrusion molding a composition comprising a polyolefin-based resin and an inorganic filler (for example, calcium carbonate). Since the composition flows in the machine direction during extrusion, the inorganic filler is oriented in the machine direction.

  In the present invention, the technical matter “stretches in at least one axial direction” is adopted. Therefore, in the direction in which the film is formed, longitudinal stretching (longitudinal stretching: MD) and / or transverse stretching (short direction stretching: TD) can be performed. By “stretching at least in a uniaxial direction”, excellent tactile sensation and design (glossiness) can be imparted to the produced film. As the design (glossiness), for example, a pearl tone or a hologram tone can be imparted to the film. As shown in FIG. 2, by stretching in the machine direction, the film around the inorganic filler (calcium carbonate) is stretched in the machine direction to form pores (vent holes). In addition, as shown in FIG. 3, by stretching in the transverse direction, the film around the inorganic filler (calcium carbonate) is stretched in the transverse direction to form pores (vent holes). By stretching the film in an appropriate direction and an appropriate magnification, ΔE becomes less than 20, and it is possible to impart concealability to the film and to impart suitable tactile sensation, design and low density. Become.

(Stretching)
In the film in the present invention, the film is formed by stretching in at least a uniaxial direction (longitudinal or lateral). The stretching is preferably performed in the transverse direction of the film. In the present invention, the stretching ratio in the transverse direction of the film is 1.0 or more and 8.0 or less, preferably 1.2 or more and 7.0 or less, and more preferably 2. It is 0 times or more and 6.0 times or less. Further, the stretching may be performed in the longitudinal direction of the film. The draw ratio of the film in the machine direction is 1.0 to 8.0 times, preferably 1.01 to 6.0 times, more preferably 1.05 to 4.0 times. Is less than double.
By setting the draw ratio within the above range, it is possible to obtain a polyolefin-based porous film having excellent tactile sensation, design (glossiness), and air permeability, and also concealing properties.

According to a preferred embodiment, stretching is preferably performed in the transverse direction of the film and the longitudinal direction of the film.
As a result, it is possible to form a porous film rapidly, and to obtain a film having excellent tactile sensation and design, high air permeability, and mechanical strength. Stretching in the transverse direction and the longitudinal direction may be performed simultaneously (preferably) or may be performed after one is performed first. According to a more preferred aspect of the present invention, the stretching is more preferably carried out with the stretching ratio in the transverse direction of the film being larger than the stretching ratio in the longitudinal direction of the film. By adjusting the draw ratio, it becomes possible to have a large number of pores, and a polyolefin porous film having excellent tactile sensation and design, high breathability, permeability and concealment, and mechanical strength is obtained. It becomes possible.

According to a more preferred embodiment, the product of the stretching ratio in the transverse direction of the polyolefin porous film and the stretching ratio in the longitudinal direction of the polyolefin porous film is 3.0 or more and 10.0 or less, more preferably 3.2 or more and 8.0 or less.
By making the product of the stretching ratio in the transverse direction and the stretching ratio in the longitudinal direction of the film a high ratio of 3.0 or more, it is possible to realize excellent tactile sensation, design and further characteristics. Become.

(Glossiness)
The polyolefin-based porous film has a 60 ° gloss of 3.0 or more and 20.0 or less, more preferably 3.2 or more and 10.0 or less.
High glossiness is achieved by the presence of inorganic fillers and form stretching. Glossiness (sex) preferably means that which achieves a pearl shade. As a result, it is possible to achieve a high-class feeling and shielding property for the product.

  The numerical value and measuring method of “60 ° gloss” are determined and measured based on JIS K 5600-4-7. If this content is outlined according to the present invention, this standard is a test method for measuring the specular gloss of a coating film using a reflectometer having a geometric condition of 60 °. The “specular gloss” is expressed as a ratio of a light beam reflected from the object in the specular direction at a specified light source and light receiver angle to a light beam reflected in the specular direction from glass having a refractive index of 1.567. As a remark, in order to clarify the standard of specular glossiness, a polished black glass having a refractive index of 1.567 is set to a value of 100 under a geometric condition of 60 °. The “60 ° gloss” can be measured using a gloss measuring instrument (for example, Gloss Checker IG-320: manufactured by Horiba, Ltd.).

(Color difference ΔE)
In the present invention, after a white reference plate or a black reference plate is overlaid on one side of the film, an L ^* a ^* b ^* table is provided on the other side of the film without the white or black reference plate. The color system is measured and adjusted so that the color difference ΔE calculated by the following mathematical formula (Formula 1) is less than 20.
ΔE = {(L ₁ ^* −L ₂ ^* ) ² + (a ₁ ^* −a ₂ ^* ) ² + (b ₁ ^* −b ₂ ^* ) ² } ^1/2
(Formula 1)
In Equation 1, "1" by the L ^* a ^* b ^* color system, a and colorimetry by the white reference plate L ^* a ^* b ^* color system, "2" was colorimetry black reference plate L ^* a ^* b ^* color system.

  The color difference ΔE is less than 20, preferably 15 or less, and more preferably 10 or less. When the color difference ΔE is within the above numerical value, it becomes possible to impart non-transparency (turbidity) to the film, that is, concealment, suppress visibility of dirt, etc., and prevent permeability in clothes. Therefore, it is possible to effectively prevent see-through.

The color difference ΔE is measured by superimposing a white standard plate on one side of the film according to the present invention, and calculating L ₁ ^* , a ₁ ^* , b ₁ ^* on the other side without the white standard plate, using a colorimeter ( K3 Minota, manufactured by Konica Minolta Co., Ltd., and a black standard plate is overlaid on one side of the film according to the present invention, and L ₂ ^* , a ₂ ^* , b _{2 on the} other side not overlaid with the black standard plate. ^* Can be measured using a colorimeter, and the numerical value can be introduced into the above formula (Formula 1) and calculated. As the white reference plate and the black reference plate, BCRA tile (manufactured by Sakata Inx Engineering Co., Ltd.) certified by the British Ceramic Research Association (BCRA) was used.

(Physical properties)
In the present invention, the thickness of the film is 5 μm or more and 100 μm or less, preferably 10 μm or more and 50 μm or less. When the film is within the above-mentioned thickness range, the tensile strength and tear strength of the film can be ensured, and at the same time, a supple (silk-like) tactile feel can be obtained. As described in the examples, the thickness of the film can be measured in accordance with the JIS method, and for example, a measuring machine (sickness gauge manufactured by Mitutoyo Corporation) can be used.

The density of the film is at 1.5 g / cm ³ or less, preferably 1.10 g / cm ³ or less. When the film is in the above density range, it is possible to manage the weight and air permeability of the film in a better state.

The moisture permeability of the film is 5300 g / m ² · 24 hr or more, preferably 5500 g / m ² · 24 hr or more, more preferably 6000 g / m ² · 24 hr or more. Thereby, very high air permeability and moisture permeability can be exhibited.

(Polyolefin resin)
In the present invention, a polyolefin-based resin is used, and the addition amount thereof is 20% by mass or more and 80% by mass or less, preferably 30% by mass or more and 65% by mass or less with respect to the total amount of the composition. . Although there is a balance with the amount of inorganic filler added, if the amount added is within the above range, the air permeability of the film can be set high, the mechanical strength is stable, and film breakage is effectively suppressed. It is preferable because tactile sensation, design, breathability and concealment can be made higher than desired.

  Specific examples of the polyolefin resin used in the present invention include, for example, homopolymers of α-olefins such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, and the co-polymerization of two or more α-olefins. Polymers, copolymers of α-olefins and other monomers copolymerizable with α-olefins, mixtures of these polymers, and the like can be used.

  According to a preferred embodiment of the present invention, among polyolefin resins, high density polyethylene, low density polyethylene, and linear low density polyethylene are preferable, and linear low density polyethylene that is a copolymer of ethylene and α-olefin is low. A mixture with density polyethylene is more preferably used. Specific examples of the linear low density polyethylene include copolymers of ethylene and α-olefins having 4 to 8 carbon atoms such as 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene and the like. It is done.

(Inorganic filler)
In the present invention, an inorganic filler is used as an essential component, and the addition amount thereof is 20% by mass or more and 80% by mass or less, preferably 35% by mass or more and 70% by mass with respect to the total amount of the composition. It is as follows. Although there is a trade-off with the amount of olefin resin added, if the amount is within the above range, the air permeability of the film can be set high, the mechanical strength is stable, and film breakage and the like are effectively suppressed. It is preferable because the concealability and tactile sensation can be set to desired levels.

  Specific examples of the inorganic filler include inorganic salts such as calcium carbonate, barium sulfate, calcium sulfate, barium carbonate, magnesium hydroxide and aluminum hydroxide; inorganic oxides such as zinc oxide, magnesium oxide and silica; mica, vermiculite, Examples thereof include silicates such as talc and organometallic salts, and these can be used alone or in combination. In the present invention, calcium carbonate is particularly used from the viewpoint of availability and cost.

  The average particle diameter of the inorganic filler is preferably 0.1 μm or more and 10 μm or less. When the average particle size of the inorganic filler is in the above range, the resulting porous film has good dispersibility, easy formation of communication holes during stretching, and film breakage during film formation is less likely to occur. It can be manufactured with good productivity.

<Surface treatment>
In the present invention, a surface-treated inorganic filler can be used. Examples of the surface treatment agent include chain carboxylic acids having 3 to 6 carbon atoms, which may be, in particular, those having a linear or branched chain, and those having a plurality of monocarboxylic acids and carboxyl groups. There may be. Specific examples include saturated monobasic acids such as propionic acid, butyric acid, valeric acid and caproic acid, saturated dibasic acids such as succinic acid and adipic acid; unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid and pentenoic acid. And unsaturated dicarboxylic acids such as maleic acid.

(Optional component)
The resin composition in the present invention comprises polyolefin and an inorganic filler as essential components. Besides these, as optional components, for example, antioxidants, weathering agents, pigments, plasticizers, charging agents In order to obtain an additive such as an inhibitor and uniform stretchability, a stretching aid such as silicone oil or wax may be blended.

[Production method of polyolefin-based porous film]
A method for producing a polyolefin-based porous film as a second aspect is proposed.

(Preparation of resin composition)
In the second aspect, a polyolefin resin of 20% by mass or more and 80% by mass or less, an inorganic filler of 20% by mass or more and 80% by mass or less, and an optional component as necessary are prepared. Prepare the product.
After bringing the above components into a container, it can be prepared by a known mixing and granulating method, and specific examples thereof include mixing with a Henschel mixer, super mixer, tumbler mixer, etc. It is possible to knead and pelletize with a twin-cut extruder, tandem kneader, or the like by a method such as strand cut, hot cut, or underwater cut.

(Film forming)
In the second aspect, the film can be formed by an extrusion method, a solution casting method, a calendar method, or the like. Generally, the inflation method and T- Film forming is performed using a die forming method. Of course, the mixed resin composition can be formed into a film as it is without carrying out the granulation described in the previous section (Preparation of resin composition).

(Stretching)
In the second aspect, the film is stretched in at least a uniaxial direction after the film molding or simultaneously with the molding.
In the second aspect, the stretching method is not particularly limited, and a known stretching method is employed. For example, uniaxial stretching by roll, tenaxial stretching after uniaxial stretching, sequential biaxial stretching by a stretching mandrel, etc., or simultaneous biaxial stretching can be mentioned. It is preferable from the point of control.

  As the stretching conditions, it is preferable that the uniaxial stretching temperature is lower than the melting point of the polyolefin. By performing uniaxial stretching at a temperature lower than the melting point, it is possible to suppress stretching load increase and enable uniform stretching, and due to the porosity formed around the polyolefin and the inorganic filler, porosity, concealment, It is possible to sufficiently exhibit the preferable tactile sensation.

(Glossiness adjustment)
In the second aspect, the polyolefin-based porous film has a 60 ° gloss of 3.0 or more and 20 or less, more preferably 3.2 or more and 10.0 or less.
High glossiness is achieved by the presence of inorganic fillers and form stretching.

(Color difference ΔE adjustment)
In the second aspect, after the white reference plate or the black reference plate is overlaid on one surface of the film, the L ^* a ^* b on the other surface of the film on which the white reference plate or the black reference plate is not overlaid. ^* Measurement is performed using a color system, and the composition is prepared and stretched so that the color difference ΔE calculated by the following mathematical formula (Formula 1) is less than 20.
ΔE = {(L ₁ ^* −L ₂ ^* ) ² + (a ₁ ^* −a ₂ ^* ) ² + (b ₁ ^* −b ₂ ^* ) ² } ^1/2
(Formula 1)

[Use]
The film according to the first aspect is used for various products, but is preferably used for hygiene products (disposable diapers, pants, sanitary products), clothing items (breathable shirts, shirts, jumpers, etc.) and the like. .

  The contents of the present invention will be described in detail using the following examples and comparative examples, but the contents of the present invention are not construed as being limited to the contents of these examples, and these examples Discloses preferred embodiments that can be implemented by those skilled in the art, and it goes without saying that those skilled in the art can implement all the inventions within the scope of the present invention based on these embodiments.

[Example 1]
After mixing 50% by mass of polyethylene and 50% by mass of calcium carbonate with a tumbler mixer, a strand kneaded and prepared at 150 ° C. to 250 ° C. with a twin screw extruder was underwater cut to obtain a resin mixture.
In the extrusion molding step, the resin composition was melted at a temperature of 150 ° C. to 250 ° C. with an extruder, and discharged from a T die onto a cast roll.
Next, using a tenter device that grips both ends of the film in the width direction with a clip and stretches horizontally, and stretches in the film width direction, 50 ° C. to 150 ° C. The film was stretched in the width direction (TD direction) by heat treatment at a temperature of ° C. The stretching ratio in the longitudinal direction and the stretching ratio in the transverse direction were 1.0 times x 3.0 times. That is, no longitudinal stretching was performed. A film was obtained by this stretching.

[Example 2]
A film was obtained in the same manner as in Example 1 except that the stretching in the longitudinal direction was further performed. The draw ratio in the longitudinal direction and the draw ratio in the transverse direction were 2.0 times 2.0 times.
Stretching in the machine direction includes a heating roll group that rotates at a low speed and a heating roll group that rotates at a higher speed than the heating roll group. Was stretched in the machine direction (MD direction).

Example 3
A film was obtained in the same manner as in Example 2 except that the stretching ratio in the vertical direction and the stretching ratio in the horizontal direction were set to 3.0 × 1.0.

Example 4
A film was obtained in the same manner as in Example 2 except that the stretching ratio in the longitudinal direction and the stretching ratio in the lateral direction were 1.5 × 4.0.

[Comparative Example 1]
A film was obtained in the same manner as in Example 2 except that the stretching ratio in the longitudinal direction and the stretching ratio in the lateral direction were 1.8 × 1.0. That is, the transverse stretching was not performed.

[Comparative Example 2]
A film was obtained in the same manner as in Comparative Example 1 except that the stretching ratio in the longitudinal direction and the stretching ratio in the lateral direction were changed to 2.2 times x 1.0 times.

[Comparative Example 3]
A film was obtained in the same manner as in Comparative Example 1 except that the stretching ratio in the longitudinal direction and the stretching ratio in the lateral direction were 2.8 × 1.0.

[Comparative Example 4]
A film was obtained in the same manner as in Comparative Example 1 except that the stretching ratio in the longitudinal direction and the stretching ratio in the lateral direction were 1.0 × 1.5.

[Comparative Example 5]
A film was obtained in the same manner as in Comparative Example 1 except that the stretching ratio in the longitudinal direction and the stretching ratio in the lateral direction were 1.0 × 2.5 times.

〔Evaluation test〕
The following evaluation was performed and the results are shown in Table 1 below.
(Tactile evaluation)
The tactile sensation touched by 10 testers (panelists) of men and women 18 to 65 years old was evaluated according to the following criteria as the number of persons judged to have good tactile sensation.
Evaluation criteria:
A: All 10 persons judged to be preferable.
B: It was judged that 7 or more and less than 10 were preferable.
C: It was judged that 4 or more and less than 7 were preferable.
E: It was judged that less than 4 people were preferable.
(Glossiness evaluation)
Measurement method: Measured with “Gloss Checker IG-320 (Horiba, Ltd.)” in accordance with JIS K 5600-4-7.
Evaluation criteria: Glossiness of 3.0 to 20.0 (evaluation of luxury)
Evaluation method: Judgment was made based on the following criteria from the results of tactile evaluation and glossiness evaluation.
Evaluation criteria:
A: Tactile sensation B or higher, and glossiness of 7.0 or higher.
A: Tactile sensation C and glossiness of 3.0 or more.
(Triangle | delta): It is tactile property E and glossiness was 3.0 or more.
X: Tactile sensation E, glossiness was 3.0 or less.
(Thickness measurement)
The thickness (μm) of the film was measured with a thickness gauge according to JIS K 6734.
(Basis weight)
About the film, basic weight (g / m < ² >) was measured with the electronic balance according to JISP8124 method.
(density)
The density (g / cm ³ ) of the film was measured with a specific gravity bottle according to JIS Z 8807 method.
(Moisture permeability)
With respect to the film, the amount of water vapor (g / m ² · 24 hr) passing through the film was measured according to the JIS Z0208 method under the conditions of a temperature of 40 ° C. and a relative humidity of 90%.
(Concealment evaluation)
After obtaining the calculated value of ΔE according to the description in (Color difference ΔE) of this specification, it was evaluated according to the following criteria.
Evaluation criteria A: ΔE is less than 10 B: ΔE is 10 or more and less than 15 C: ΔE is 15 or more and less than 20 E: ΔE is 20 or more

[Evaluation]
As shown in Table 1, it was shown that the basis weights of the examples and comparative examples were both within a substantially constant numerical range. However, the example had a smaller density and a larger thickness than the comparative example. That is, the film of the obtained example is remarkably high in the ratio of the pore portion per unit volume as compared with that of the comparative example, and has excellent tactile sensation, design, luxury, and It was clearly understood to have concealment.

FIG. 1 is a schematic diagram showing extraction molding in the vertical direction and the horizontal direction in the present invention. FIG. 2 is a schematic diagram showing the stretching in the longitudinal direction in the present invention. FIG. 3 is a schematic diagram showing the stretching in the transverse direction in the present invention.

Claims (18)

A polyolefin-based porous film,
20% by mass or more and 80% by mass or less polyolefin-based resin;
Comprising 20% by mass or more and 80% by mass or less of an inorganic filler,
The film is stretched in at least a uniaxial direction,
A film having a 60 ° gloss of 3.0 or more.   The film according to claim 1, wherein the stretching is performed in a transverse direction of the film.   The film of Claim 1 or 2 whose draw ratio to the horizontal direction of the said film is 1.0 time or more and 8.0 times or less.   The film according to any one of claims 1 to 3, wherein the stretching is performed in a longitudinal direction of the film.   The film of Claim 4 whose draw ratio to the vertical direction of the said film is 1.0 time or more and 8.0 times or less.   The film according to claim 4 or 5, wherein a stretching ratio in the transverse direction of the film is larger than a stretching ratio in the longitudinal direction of the film.   The film of Claim 4 or 5 whose product of the draw ratio to the horizontal direction of the said film and the draw ratio to the longitudinal direction of the said film is 3.0 or more. The thickness of the film is 5 μm or more and 100 μm or less,
The film as described in any one of Claims 1-7 whose density of the said film is 1.5 g / cm < ³ > or less. A white standard plate is overlaid on one side of the film, and L ₁ ^* , a ₁ ^* , b ₁ ^* of the other side of the film without the white standard plate is measured, and one side of the film A black standard plate is overlapped on the surface, and L ₂ ^* a ₂ ^* b ₂ ^* of the other surface where the black standard plate is not overlapped is measured, and the color difference ΔE calculated by the following equation (Equation 1) is less than 20. The film as described in any one of Claims 1-8 which exists.
ΔE = {(L ₁ ^* −L ₂ ^* ) ² + (a ₁ ^* −a ₂ ^* ) ² + (b ₁ ^* −b ₂ ^* ) ² } ^1/2
(Formula 1) A method for producing a polyolefin-based porous film,
20% by mass or more and 80% by mass or less polyolefin-based resin;
Preparing a composition comprising 20% by mass or more and 80% by mass or less of an inorganic filler;
Forming the composition into a film;
Stretching the film at least in a uniaxial direction;
A manufacturing method in which the 60 ° glossiness is 3.0 or more.   The manufacturing method according to claim 10, wherein the stretching is performed in a transverse direction of the film.   The manufacturing method of Claim 11 whose draw ratio to the horizontal direction of the said film is 1.0 time or more and 8.0 times or less.   The manufacturing method according to claim 10, wherein the stretching is performed in a longitudinal direction of the film.   The manufacturing method of Claim 13 whose draw ratio to the vertical direction of the said film is 1.0 time or more and 8.0 times or less.   The manufacturing method according to claim 13 or 14, wherein a stretching ratio in the transverse direction of the film is larger than a stretching ratio in the longitudinal direction of the film.   The manufacturing method according to claim 14 or 15, wherein a product of a stretching ratio in the transverse direction of the film and a stretching ratio in the longitudinal direction of the film is 3.0 or more. The thickness of the film is 5 μm or more and 100 μm or less,
The manufacturing method as described in any one of Claims 11-16 whose density of the said film is 1.5 g / cm < ³ > or less. A white standard plate is overlaid on one side of the film, and L ₁ ^* , a ₁ ^* , b ₁ ^* of the other side of the film without the white standard plate is measured, and one side of the film A black standard plate is superimposed on the surface, and L ₂ ^* a ₂ ^* b ₂ ^* of the other surface of the film without the black standard plate is measured, and the color difference ΔE calculated by the following equation (Equation 1) is The manufacturing method as described in any one of Claims 10-17 which becomes less than 20.
ΔE = {(L ₁ ^* −L ₂ ^* ) ² + (a ₁ ^* −a ₂ ^* ) ² + (b ₁ ^* −b ₂ ^* ) ² } ^1/2
(Formula 1)

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