JP6358603B2 - Laminated film - Google Patents

Description

The present invention relates to a laminated film having a multilayer structure, which contains high aspect ratio magnesium hydroxide and is excellent in gas barrier properties, transparency and acid resistance.

Various functions are required for packaging, but various gas barrier properties for the purpose of protecting the contents are important properties that affect the preservation of foods. Distribution forms, diversification of packaging technology, additive regulations, and changes in preferences As a result, the need is growing. And gas barrier property was also a weak point of a general plastic material. Examples of factors that alter the quality of food include oxygen, light, heat, and moisture. In particular, oxygen is important as a causative substance. The barrier material is an essential material for the means to effectively block the oxygen and at the same time to control the quality change of food such as gas filling and vacuum packaging, such as not only oxygen gas but also various gases, organic solvent vapor, aroma, etc. By having a barrier function, it can be used for rust prevention, deodorization, and sublimation prevention, and is suitably used in many packaging fields such as processed foods, fresh foods, cosmetics, agricultural chemicals, and pharmaceuticals.

Among films made of thermoplastic resin, films such as polyethylene and polypropylene have excellent mechanical properties and transparency, and are widely used as packaging materials. However, when these films are used for food packaging, the oxygen and other gas barrier properties are insufficient, which can easily lead to oxidative deterioration and alteration of the contents due to aerobic microorganisms, or permeation of perfume components. Therefore, various problems are liable to occur, such as the loss of flavor and the content being moistened with moisture from the outside world, resulting in poor mouthfeel. Therefore, usually, a method such as laminating other film layers having good gas barrier properties is often used.

As a method for developing gas barrier properties, there is a method for dispersing an inorganic substance having a high aspect in a resin. For example, in Japanese Patent Laid-Open No. 64-043554, mica having an average width of 7 μm and an aspect ratio of 140 is added to an aqueous methanol solution of an ethylene / vinyl alcohol copolymer, and this is poured into cold water and precipitated. A method is described which is filtered, dried, pelleted and then a film is obtained. (Patent Document 1)

  Japanese Patent Laid-Open No. 7-251486 has at least one layer composed of an inorganic layered compound having a particle size of 5 μm or less and an aspect ratio of 50 to 5000 in a layer mainly composed of polyvinylidene chloride and a resin. A laminated film is described. (Patent Document 2)

Furthermore, JP-A-2002-36448 discloses that 1 to 25 parts by weight of an inorganic filler (B) having a weight average aspect ratio of 5 or more and / or a particle diameter of 0.1 parts per 100 parts by weight of the barrier resin (A). Weight average with respect to the layer which consists of a resin composition (C) which contains 0.5-10 weight part of 5-10 micrometers deodorizer (F), and thermoplastic resins (D) other than the said resin (A). A resin composition (E) containing 1 to 25 parts by weight of an inorganic filler (B) having an aspect ratio of 5 or more and / or 0.5 to 10 parts by weight of a deodorizer (F) having a particle size of 0.5 to 10 μm ), A multilayer structure formed by stretching a multilayer structure formed by laminating at least two times in a uniaxial direction is described. (Patent Document 3)

  On the other hand, the demand for magnesium hydroxide is rapidly increasing as an inorganic filler that is harmless to the human body and has a low environmental load. The present inventors have established a technique for controlling the lateral width, thinness, and dispersibility of crystals by controlling the types of additives added during synthesis and reaction conditions. WO2012 / 050222 describes magnesium hydroxide having a major axis (horizontal width) of 0.5 μm or more and an aspect ratio of 10 or more, and that it can be used as a gas barrier property improving agent for packaging resin films. (Patent Document 4)

However, the film prepared by the conventional technique using magnesium hydroxide disclosed in Patent Document 4 cannot be said to have sufficient performance in terms of gas barrier properties. Furthermore, problems such as a decrease in transparency caused by blending a large amount of an inorganic filler and dissolution of magnesium hydroxide due to contact with an acidic substance have occurred.

Japanese Patent Application Laid-Open No. 64-043554 Japanese Patent Laid-Open No. 7-251486 JP 2002-36448 A WO2012 / 050222

An object of the present invention is to provide a film containing magnesium hydroxide as an active ingredient and having high gas barrier properties. Another object of the present invention is to provide a film that prevents deterioration of transparency when a large amount of magnesium hydroxide is blended and prevents dissolution of magnesium hydroxide due to contact with an acidic substance.

  The present inventors have intensively studied on improvement of gas barrier property, prevention of lowering of transparency, and prevention of dissolution of magnesium hydroxide by an acidic substance in a film containing magnesium hydroxide. As a result, by making the film a specific structure, it was discovered that a gas barrier property higher than the conventional one was developed, transparency was improved at the same time, and dissolution of magnesium hydroxide by an acidic substance could be prevented. It came.

  In this invention, it is a laminated film which has layer A and layer B, and has layer A on the outermost surface, Comprising: Layer A consists of a thermoplastic resin, Layer B is (1) with respect to 100 weight part of thermoplastic resins. The average primary particle width measured by the SEM method is 1 μm or more and 20 μm or less, (2) the average primary particle thickness measured by the SEM method is 10 nm or more and 200 nm or less, and (3) the average aspect ratio of the secondary particles ( 1 to 200 parts by weight of magnesium hydroxide having an average width of secondary particles measured by laser diffraction method / average thickness of secondary particles measured by SEM method of 10 or more and 200 or less. Provide film.

In the laminated film of the present invention, magnesium hydroxide is more easily oriented than the conventional single-layer film, and high gas barrier properties are exhibited by blocking the air passage. Furthermore, in the conventional single-layer film, magnesium hydroxide is exposed on the film surface, and when this is exposed to light, irregular reflection occurs, causing a decrease in transparency. By protecting with layer A, the surface was smoothed and this problem was overcome. Furthermore, in the conventional single layer film, magnesium hydroxide is dissolved by contacting an acidic substance with magnesium hydroxide exposed on the surface, but layer B containing magnesium hydroxide is protected by layer A. This overcomes this problem.

The laminated film of the present invention has high gas barrier properties, good transparency, and good acid resistance, so it can be used for rust prevention, deodorization, sublimation prevention, processed food, fresh food, cosmetics, agricultural chemicals, pharmaceuticals Etc., and can be suitably used as packaging materials in many fields.

It is a schematic diagram explaining the structure of the laminated | multilayer film of this invention. It is a schematic diagram explaining the width and thickness about the primary particle of magnesium hydroxide mix | blended with the layer B of the laminated | multilayer film of this invention. It is a schematic diagram explaining the width and thickness about the secondary particle of magnesium hydroxide mix | blended with the layer B of the laminated | multilayer film of this invention. It is a 20000 times SEM photograph of Kisuma 10A (magnesium hydroxide) contained in the film of Example 1 and Comparative Example 1. 4 is a SEM photograph of 20000 times that of Kisuma 5A (magnesium hydroxide) contained in the film of Comparative Example 2. 2 is a 1000 times SEM photograph of a cross-section of the laminated film of Example 1. FIG. 2 is a 5000 times SEM photograph of a cross section of the laminated film of Example 1. FIG. 2 is a 1000 times SEM photograph of a cross section of a single layer film of Comparative Example 1 observed. It is a 1000 times SEM photograph which observed the section of the lamination film of comparative example 2. 4 is a 5000 times SEM photograph of a cross-section of a laminated film of Comparative Example 2. FIG. 2 is a 1000 times SEM photograph observing the surface state of the laminated film of Example 1. FIG. 2 is a 1000 times SEM photograph observing the surface state of a single layer film of Comparative Example 1. FIG.

Hereinafter, the present invention will be specifically described.

The laminated film of the present invention has a multilayer structure consisting of layer A and layer B. Hereinafter, the layer A, the layer B, and the laminated film will be specifically described.

(Layer A)
The layer A of the present invention is made of a thermoplastic resin. The type of the thermoplastic resin is not particularly limited. For example, polyethylene, a copolymer of ethylene and another α-olefin, a copolymer of ethylene and vinyl acetate, a copolymer of ethylene and acrylate ether, ethylene And methyl acrylate copolymer, polypropylene, copolymer of propylene and other α-olefin, polybutene-1, poly-4-methylpentene-1, polystyrene, copolymer of styrene and acrylonitrile, ethylene and Copolymer of propylene diene rubber, copolymer of ethylene and butadiene, polyvinyl acetate, polylactic acid, polyvinyl alcohol, polyacrylate, polymethacrylate, polyurethane, polyester, polyether, polyamide, ABS, polycarbonate, polyphenylene sulfide Can be mentioned. Preferably, at least one selected from polyethylene and polypropylene is used.

(Layer B)
The layer B of the present invention has (1) an average primary particle width of 1 μm or more and 20 μm or less of primary particles measured by the SEM method, and (2) an average of primary particles measured by the SEM method with respect to 100 parts by weight of the thermoplastic resin. The thickness is 10 nm or more and 200 nm or less, and (3) the average aspect ratio of secondary particles (average width of secondary particles measured by laser diffraction method / average thickness of secondary particles measured by SEM method) is 10 or more and 200 or less. Contains 1 to 200 parts by weight of magnesium hydroxide.

The type of the thermoplastic resin is not particularly limited. For example, polyethylene, a copolymer of ethylene and another α-olefin, a copolymer of ethylene and vinyl acetate, a copolymer of ethylene and acrylate ether, ethylene And methyl acrylate copolymer, polypropylene, copolymer of propylene and other α-olefin, polybutene-1, poly-4-methylpentene-1, polystyrene, copolymer of styrene and acrylonitrile, ethylene and Copolymer with propylene diene rubber, copolymer of ethylene and butadiene, polyvinyl acetate, polylactic acid, polyvinyl alcohol, polyacrylate, polymethacrylate, polyurethane, polyester, polyether, polyamide, ABS, polycarbonate, polyphenylene sulfide Can be mentioned. Preferably, at least one selected from polyethylene and polypropylene is used.

Magnesium hydroxide blended in the layer B of the present invention is represented by the chemical formula Mg (OH) _{2 and} the primary particles are plate-like. The primary particles defined in the present invention are particles having a clear boundary that cannot be further divided geometrically. FIG. 2 is a schematic diagram for explaining the width and thickness of the primary particles. As shown in FIG. 2, the lateral width W _{1 of} the primary particles and the thickness T _{1 of the} primary particles are defined. That is, when the primary particle is a hexagonal plate surface, the major axis of the particle is “lateral width W _{1 of} primary particle”, and the thickness of the plate surface is “primary particle thickness T ₁ ”. The average horizontal width of the primary particles of magnesium hydroxide blended in the layer B of the present invention is 1 μm or more and 20 μm or less, preferably 1.5 μm or more and 20 μm or less, more preferably 2 μm or more and 20 μm or less. The average thickness of the primary particles is from 10 nm to 200 nm, preferably from 10 nm to 150 nm, and more preferably from 10 nm to 100 nm. The average width and average thickness of the primary particles are determined from the arithmetic average of the measured values of the width and thickness of any 100 crystals in the SEM photograph by the SEM method. The width and thickness of primary particles cannot be measured by laser diffraction in principle. Therefore, it confirms visually by SEM method.

The secondary particles defined in the present invention are particles in which a plurality of primary particles gather to form an aggregate. FIG. 3 is a schematic diagram for explaining the width and thickness of the secondary particles. As shown in FIG. 3, the width W _{2 of} the secondary particles and the thickness T _{2 of the} secondary particles are defined. That is, since the primary particles have a hexagonal plate surface, when the primary particles are stacked in the thickness direction of the plate surface to become secondary particles, the total of the stacked primary particles in the plate surface direction. The thickness is “secondary particle thickness T ₂ ” and the maximum diagonal length of the stacked primary particles, that is, the diameter of the sphere when the secondary particles are considered to be wrapped by the sphere is “secondary particle”. Width W ₂ ”. The average lateral width of the secondary particles of magnesium hydroxide blended in the layer B of the present invention is measured by a laser diffraction method, and the average thickness of the secondary particles is determined by the SEM method for any 100 crystals in the SEM photograph. It calculates | requires from the arithmetic average of the measured value of the thickness of a secondary particle. The thickness of secondary particles cannot be measured by laser diffraction in principle. Therefore, it confirms visually by SEM method.

The average aspect ratio of the secondary particles is 10 or more and 200 or less, preferably 15 or more and 200 or less, more preferably 20 or more and 200 or less. The average aspect ratio of the secondary particles is determined from the average width of the secondary particles and the average thickness of the secondary particles measured above.

The BET specific surface area of magnesium hydroxide blended in the layer B of the present invention is 1 m ² / g or more and 30 m ² / g or less, preferably 2 m ² / g or more and 25 m ² / g or less, more preferably 3 m ^2. / G to 20 m ² / g.

  Magnesium hydroxide blended in the layer B of the present invention includes anionic surfactants, phosphate esters, silane coupling agents, titanate coupling agents, aluminum coupling agents, silicone treatment agents, water glass, silica, And at least one selected from the group consisting of cationic surfactants. The amount of the surface treatment agent is 0.1 to 20% by weight, preferably 0.5 to 5% by weight, based on the weight of magnesium hydroxide. By subjecting magnesium hydroxide to surface treatment, dispersibility and acid resistance when blended in a film can be improved.

  Magnesium hydroxide blended in the layer B of the present invention is characterized by a remarkably low content of heavy metals such as Fe and Mn. The total content of Fe and Mn is 200 ppm or less, preferably 150 ppm or less, more preferably 100 ppm or less. If the content of Fe and Mn is more than 200 ppm, the film is colored or the transparency is lowered, which is not preferable.

(Laminated film)
The laminated film of the present invention has layer A and layer B, and has layer A on the outermost surface. For example, there are an ABA structure, an ABABA structure, an ABABABA structure, and the like, but not limited thereto. Protecting layer B containing magnesium hydroxide with layer A prevents exposure of magnesium hydroxide to the film surface, lowers transparency due to light scattering, and dissolves magnesium hydroxide due to contact with acidic substances Can be prevented. In FIG. 1, the schematic diagram of the laminated | multilayer film of this invention is shown.

In the laminated film of the present invention, the thickness of the layer A is 1 to 100 μm, preferably 1 to 80 μm, and more preferably 1 to 50 μm. The thickness of the layer B is 1 to 200 μm, preferably 1 to 150 μm, and more preferably 1 to 100 μm.

When X-ray diffraction is performed on the surface of the laminated film of the present invention, the ratio (orientation degree) of the integrated intensity of the peak of the (001) plane to the integrated intensity of the peak of the (101) plane and the (110) plane is 30. It is above, Preferably it is 40 or more, More preferably, it is 50 or more. The more magnesium hydroxide is oriented, the more the air path is blocked and the higher the gas barrier properties.

(Laminated film manufacturing method)
The laminated film of the present invention can be produced by a molding method such as T-die molding, inflation molding or extrusion molding, but is not limited thereto.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited only to these examples. In the examples, each physical property was measured by the following method.

(A) After adding an average width and thickness sample of primary particles to ethanol and performing ultrasonic treatment for 5 minutes, using a scanning electron microscope (SEM) (manufactured by JEOL, JSM-7600F), any 100 particles The lateral width and thickness of the primary particles of the crystal were measured, and the arithmetic average was taken as the average lateral width and thickness of the primary particles.

(B) An average width sample of secondary particles was added to ethanol and subjected to ultrasonic treatment for 5 minutes, and then the particle size distribution was measured using a laser diffraction particle size analyzer (manufactured by Microtrac Bell, Microtrac MT3000). The volume average diameter was taken as the average width of the secondary particles.

(C) An average thickness sample of secondary particles was added to ethanol and subjected to ultrasonic treatment for 5 minutes, and then, using a scanning electron microscope (SEM) (manufactured by JEOL, JSM-7600F), an arbitrary 100 2 The thickness of the secondary particles was measured, and the arithmetic average was taken as the average thickness of the secondary particles.

(D) Average aspect ratio of secondary particles Based on the following formula, the average aspect ratio was calculated from the values of (b) and (c) above.
Average aspect ratio of secondary particles = (Average width of secondary particles / Average thickness of secondary particles)

(E) Determination of impurities After heating and dissolving a sample in nitric acid, Fe and Mn were quantified by chelate titration.

(F) Quantification of surface treatment amount (stearic acid) The coating amount of stearic acid relative to the weight of the sample was calculated by an ether extraction method.

(G) The BET method specific surface area was measured by the gas adsorption method using a BET method specific surface area measuring device (NOVA2000, manufactured by Yuasa Ionics).

(H) The gas barrier film of the film was subjected to oxygen substitution for 2 days in an atmosphere with a humidity of 65% RH and an air temperature of 25 ° C., and then in accordance with JIS-K7126 (Method B). Gas barrier properties were measured using TRAN 2 / 22L (manufactured by MOCOM).

(I) Transparency of film Haze was measured with a haze meter (NDH-1001DP, manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS-K7105. The lower the haze, the better the transparency.

(J) The acid-resistant film was cut into 10 cm length and width, impregnated with 100 mL of 1 mol / L sulfuric acid solution, kept at a temperature of 30 ° C., and held for 24 hours. The Mg elution amount per 1 m ^{2 of} film was calculated from the Mg concentration in the solution after holding, and the acid resistance was evaluated. The smaller the Mg elution amount, the better the acid resistance.

(K) Degree of orientation of film X-ray diffractometer (Empirean, manufactured by Panalical) X-ray diffraction is performed on the film surface, and the peak on the (001) plane with respect to the integrated intensity of the peaks on the (101) plane and (110) plane The ratio of the integrated intensity was determined as the degree of orientation. The mathematical formula used for calculating the degree of orientation is as follows.

(In the formula, S was a measurement sample, R was a standard sample, and the standard sample was the film of Comparative Example 2. In001 represents the integrated intensity of the X-ray diffraction peak of the (001) plane, and ΣInhkl represents (001), (Represents the sum of the integrated intensities of the X-ray diffraction peaks of each surface of (101) and (110).)

(Preparation of layer A forming resin)
Umerit 20B (metallocene catalyst LLDPE, manufactured by Ube Maruzen Polyethylene) was melt-mixed in a tandem extruder (115 mmφ, L / D: 29) to obtain a layer A forming resin.

(Preparation of compound for layer B)
100 parts of Umerit 20B (metallocene catalyst LLDPE, manufactured by Ube Maruzen Polyethylene) and 100 parts of Kisuma 10A (manufactured by Kyowa Chemical Industry, magnesium hydroxide) are blended into a special single-screw kneader (KCK-82, manufactured by KSK Engineering) The mixture for the layer B was prepared by melting and mixing.

(Preparation of resin for forming layer B)
Using the above-mentioned compound for layer B, the mixture was melt-mixed in a tandem extruder (first stage 175 mmφ, L / D: 17, second stage 220 mmφ, L / D: 20) to obtain a resin for forming layer B. Table 1 shows the average width and thickness of primary particles of Kisuma 10A, the average width of secondary particles, the average thickness and average aspect ratio, the amount of impurities, the amount of surface treatment, and the BET specific surface area. FIG. 4 shows a 1000 times SEM photograph of Kisuma 10A.

(Production of T-die film)
The above-mentioned resin for forming layer A and resin for forming layer B are respectively melted in an extruder (two types and three layers are co-extruded), and in that state, a three-layer T die (straight manifold type, lip width 1800 mm, The laminate was extruded at a temperature of 160 ° C. within a lip gap of 2 mm). After the obtained molten resin film was cooled with a casting cooling roll, it was wound up at 15 m / min, and layer A: 12.5 μm, layer B: 25 μm, and layer A: 12.5 μm were laminated in this order. Two types of three-layer films were continuously prepared. Table 2 shows the gas barrier properties, transparency, acid resistance, and orientation of the film. FIG. 6 shows a 1000 × SEM photograph of the cross section of the laminated film of Example 1, and FIG. 7 shows a 5000 × SEM photograph. In FIG. 11, the 1000-times SEM photograph which observed the surface of the laminated | multilayer film of Example 1 is shown.

In the production of the compound for layer B in Example 1, 100 parts of Kimera 10A (magnesium hydroxide, manufactured by Kyowa Chemical Industry Co., Ltd.) was added to 100 parts of Umerit 20B (metallocene catalyst LLDPE, manufactured by Ube Maruzen Polyethylene). A laminated film was prepared. Table 2 shows the gas barrier properties, transparency, acid resistance, and orientation of the film.
(Comparative Example 1)

(Production of compound)
100 parts of Umerit 20B (metallocene catalyst LLDPE, manufactured by Ube Maruzen Polyethylene) is mixed with 33.33 parts of Kisuma 10A (magnesium hydroxide, manufactured by Kyowa Chemical Industry Co., Ltd.), and a special single-screw kneader (KCK-82, KS Engineering) The compound was prepared by melting and mixing in the product.

(Preparation of layer forming resin)
Using the above compound, the mixture was melted and mixed in a tandem extruder (first stage 175 mmφ, L / D: 17, second stage 220 mmφ, L / D: 20) to obtain a layer forming resin.

(Production of inflation film)
The layer forming resin was extruded into a tube shape at a resin temperature of 160 ° C. by an extruder equipped with an inflation ring die. Next, the tube was cooled by air cooling, inflation was performed at a blow ratio of 3 times, and the tube was wound at 15 m / min via a nip roll to obtain a single layer film having a film thickness of 50 μm. Table 2 shows the gas barrier properties, transparency, acid resistance, and orientation of the film. FIG. 8 shows a 1000 × SEM photograph of the cross section of the single layer film of Comparative Example 1, and FIG. 12 shows a 1000 × SEM photograph of the surface of the single layer film of Comparative Example 1 observed.
(Comparative Example 2)

A film was prepared in the same manner as in Example 1 except that Kisuma 5A (magnesium hydroxide, manufactured by Kyowa Chemical Industry) was used instead of Kisuma 10A (magnesium hydroxide, manufactured by Kyowa Chemical Industry). Table 1 shows the average width and thickness of primary particles of Kisuma 5A, the average width of secondary particles, the average thickness and average aspect ratio, the amount of impurities, the amount of surface treatment, and the BET method specific surface area. Table 2 shows the acid resistance and the degree of orientation. FIG. 5 shows a 1000 times SEM photograph of Kisuma 5A. FIG. 9 shows a 1000 times SEM photograph of the cross section of the laminated film of Comparative Example 2, and FIG. 10 shows a 5000 times SEM photograph.
(Comparative Example 3)

A film was also produced in the same manner as in Comparative Example 1 except that magnesium hydroxide was not blended to obtain a single layer film having a thickness of 50 μm. Table 2 shows the gas barrier properties and transparency of the film.

From Table 1, Kisuma 10A has a larger average major axis of primary particles than Kisma 5A, a smaller average thickness of primary particles, and a larger average aspect ratio of secondary particles.

From Table 2, Examples 1 and 2 have higher gas barrier properties than Comparative Examples 1, 2, and 3. Example 1 and Comparative Example 1 contain the same amount of magnesium hydroxide of the same type, but Example 1 has high gas barrier properties and suppresses elution of magnesium hydroxide. Since Comparative Example 2 contains magnesium hydroxide having a low aspect ratio of secondary particles, gas barrier properties and transparency are low.

The laminated film of the present invention has high gas barrier properties, good transparency, and good acid resistance, so it can be used for rust prevention, deodorization, sublimation prevention, processed food, fresh food, cosmetics, agricultural chemicals, pharmaceuticals Etc., and can be suitably used as packaging materials in many fields.

A ... Layer A
B ... Layer B
C ... thicknesses of T ₂ ... 2 primary particles of width T ₁ ... 1 primary particles of the width W ₂ ... 2 primary particles of magnesium hydroxide W ₁ ... 1 primary particles

Claims (9)

A laminated film having a layer A and a layer B, and having the layer A on the outermost surface. The layer A is made of a thermoplastic resin, and the layer B is measured by (1) SEM method with respect to 100 parts by weight of the thermoplastic resin. The average primary particle width is 1 μm or more and 20 μm or less, (2) the average primary particle thickness measured by the SEM method is 10 nm or more and 200 nm or less, and (3) the average aspect ratio of the secondary particles (by laser diffraction method). 1 to 200 parts by weight of magnesium hydroxide having an average width of secondary particles measured / average thickness of secondary particles measured by SEM method of 10 or more and 200 or less , and X relative to the surface of the laminated film The ratio of the integrated intensity of the peak of the (001) plane to the integrated intensity of the peak of the (101) plane and the (110) plane when the line diffraction is performed (orientation degree) is 30 or more. the film. The laminated film according to claim 1, wherein the thermoplastic resins of the layer A and the layer B are at least one selected from the group consisting of polyethylene and polypropylene. The laminated film according to claim 1, wherein the average horizontal width of the primary particles of magnesium hydroxide is 2 µm or more and 20 µm or less. The laminated film according to claim 1, wherein the average thickness of the primary particles of magnesium hydroxide is 10 nm or more and 100 nm or less. The average aspect ratio of secondary particles of magnesium hydroxide (average lateral width of secondary particles measured by laser diffraction method / average thickness of secondary particles measured by SEM method) is 20 or more and 200 or less. Laminated film. The laminated film according to claim 1, wherein the BET specific surface area of magnesium hydroxide is 1 m ² / g or more and 30 m ² / g or less. Magnesium hydroxide from the group consisting of anionic surfactants, phosphate esters, silane coupling agents, titanate coupling agents, aluminum coupling agents, silicone processing agents, water glass, silica, and cationic surfactants The laminated film according to claim 1, which is surface-treated with one or more selected. The laminated film according to claim 1, wherein the layer A has a thickness of 1 to 100 μm. The laminated film according to claim 1, wherein the layer B has a thickness of 1 to 200 μm.