JP2018144490A - LAMINATED FILM, LAMINATE FOR IMAGE DISPLAY DEVICE, AND IMAGE DISPLAY DEVICE - Google Patents

Abstract

An object of the present invention is to provide a laminated film excellent in heat insulation even if it is a thin film and excellent in workability that does not cause a decrease in heat insulation even when an adhesive or a pressure-sensitive adhesive is applied, and an image provided with the laminated film To provide a laminate for a display device and an image display device provided with the laminate for an image display device. SOLUTION: A porous layer (I) mainly composed of a propylene-based resin (A) and a layer (II) mainly composed of a propylene-based resin (B) are provided on at least one surface of the porous layer (I). And a laminated film having β crystal activity, an air permeability of 1000 seconds / dL or more, and a porosity of 50% or more. The formula (1) [NA ≦ 1; NA satisfies the pore abundance ratio of 3 μm 2 or more in the cross section of the porous layer (I) (number / 100 μm 2)], and the propylene resin (A) is the main component. A laminated film having a porous layer (I) and a layer (II) mainly composed of a propylene-based resin (B) on at least one surface of the porous layer (I). [Selection figure] None

Description

  The present application relates to a laminated film, a laminate for an image display device, and an image display device.

Thermal insulation materials are widely applied to various products such as precision instruments, home appliances, interiors of various vehicles, residential walls, ceilings, etc., which are greatly affected by temperature changes. In recent years, in mobile electronic devices such as smartphones and tablet terminals, the influence on users and internal components due to heat generation has become a problem, and a heat insulating material having a high heat insulating effect in a limited installation space has become a problem. There is a strong demand.
Conventionally, as a heat insulating material, a urethane foam obtained by foaming urethane resin with Freon gas, or a heat insulating material using hydrocarbons as a foaming gas instead of Freon gas, is used, while these heat insulating materials have high heat insulating properties, Since it is difficult to reduce the thickness of the film, its use is limited to applications that can secure a sufficient installation space.
Glass mats using glass fibers (Patent Document 1), heat insulating materials in which xerogel and / or airgel particles are dispersed in the fibers (Patent Documents 2 and 3), propylene-based resins There is a heat insulating material (Patent Document 4) made porous by stretching.
Such a heat insulating material can be easily made into a thin film and can easily follow a complicated shape. Therefore, it is easy to use even in a limited space such as the interior of various vehicles and mobile electronic devices.

  However, when using the above heat-insulating material in combination with other electronic material members, if an adhesive or pressure-sensitive adhesive made of a solvent is applied during the heat-insulating sheet processing, the adhesive or pressure-sensitive adhesive penetrates into the porous structure. In addition, there is a concern about uniform adhesiveness, as well as filling pores in the porous structure, which may reduce the heat insulation.

  On the other hand, Patent Document 5 discloses a laminated heat insulating sheet composed of a non-porous layer and a porous layer made of a propylene-based resin and an elastomer. Since the front and back layers of this sheet are non-porous layers, it is considered that the risk of the adhesive or pressure-sensitive adhesive soaking in is reduced. However, a thin and high-performance heat insulating material is required when used in a limited space such as a mobile electronic device, but a laminated heat insulating sheet obtained by the manufacturing method disclosed in Patent Document 5 is required. It has been found by the inventors that high heat insulation properties cannot be obtained.

JP-A-2005-009566 JP 2014-237910 A International Publication No. 2016/121372 JP 2007-56253 A JP, 2006-117249, A

  The present invention has been made in view of the above problems, and is excellent in heat insulation even in the case of a thin film, and has a workability that does not cause a decrease in heat insulation even when an adhesive or a pressure-sensitive adhesive is applied. It is an object of the present invention to provide an excellent laminated film, a laminate for an image display device provided with the laminated film, and an image display device provided with the laminate for an image display device.

[1] A porous layer (I) containing propylene resin (A) as a main component and a layer (II) containing propylene resin (B) as a main component on at least one side of the porous layer (I). And a laminated film having β crystal activity, an air permeability of 1000 seconds / dL or more, and a porosity of 50% or more.
[2] A porous layer (I) that satisfies the formula (1) and that has the propylene resin (A) as a main component, and at least one side of the porous layer (I) that has the propylene resin (B) as a main component A laminated film having a layer (II).
Formula (1): N _A ≦ 1
_{[N A} represents the abundance ratio of the porous layer (I) of at open area 3 [mu] m ² or more in a cross section hole (pieces / 100 [mu] m ^2). ]
[3] The laminated film according to [1] or [2], wherein the thermal conductivity is less than 0.025 W / mK.
[4] The laminated film according to any one of [1] to [3], which has a thickness of 1 μm to 300 μm.
[5] At least one surface of the laminated film according to any one of [1] to [4] includes a touch panel, an image display panel, a surface protection panel, a retardation film, a polarizing film, a color filter, and a flexible substrate. A laminate for an image display device, comprising at least one selected from the group.
[6] An image display device provided with the laminate for an image display device according to [5].

Even if it is a thin film, the laminated film of this invention is excellent in sufficient heat insulation, and even when it is a case where an adhesive agent or an adhesive is apply | coated, it does not exert a fall of heat insulation and is excellent in workability.
Specifically, in the laminated film of the present invention, the first embodiment has β crystal activity and has a fine porous structure. Furthermore, since the air permeability is 1000 seconds / dL or more and the porosity is 50% or more, the material heat transfer is reduced and excellent heat insulation is provided. In the second embodiment, since the abundance ratio of the pores having a pore area of 3 μm ² or more in the cross section of the porous layer (I) is small, the coarse pore diameter is small and the pore heat transfer is reduced.
In addition, since the laminated film of the present invention has the layer (II), when the pressure-sensitive adhesive or adhesive is applied on the layer (II), the penetration of the pressure-sensitive adhesive or adhesive is suppressed, and the internal porous structure is obtained. The derived pores are maintained, and the heat insulation is not deteriorated.
Furthermore, since the laminated film of the present invention forms a porous layer by making it porous upon stretching, it does not use a foaming agent such as gas and has high environmental compatibility. In addition, since no foaming agent is used, it is easy to make a thin film, and it can be used in limited installation spaces such as interiors of various vehicles and mobile electronic devices.

It is the cross-sectional image which image | photographed the cross section of the TD direction of the laminated film of Example 1 with the scanning electron microscope. It is a cross-sectional image which image | photographed the cross section of the TD direction of the laminated film of the comparative example 2 with the scanning electron microscope.

  The present invention will be described in detail below. However, the contents of the present invention are not limited to the embodiments described below.

1. Laminated Film A laminated film according to an example of an embodiment of the present invention (hereinafter sometimes referred to as “the present film”) has the following two forms.
The first main film includes a porous layer (I) mainly composed of a propylene-based resin (A) and a layer (II) mainly composed of a propylene-based resin (B) on at least one surface of the porous layer (I). ), Β-crystal activity, air permeability of 1000 seconds / dL or more, and porosity of 50% or more.
The second main film satisfies the formula (1), the porous layer (I) mainly composed of the propylene resin (A), and the propylene resin (B) on at least one surface of the porous layer (I). A laminated film having a layer (II) as a main component.
Formula (1): N _A ≦ 1
_{[N A} represents the abundance ratio of the porous layer (I) of at open area 3 [mu] m ² or more in a cross section hole (pieces / 100 [mu] m ^2). ]
Hereinafter, when the first main film and the second main film are collectively referred to, they are simply referred to as “main film”.

(1) Air permeability The air permeability of the first film is 1000 seconds / dL or more, preferably 5000 seconds / dL or more, and more preferably 10,000 seconds / dL or more.
The air permeability represents the difficulty in passing through the air in the thickness direction of the laminated film, and is specifically expressed in the number of seconds required for 100 ml of air to pass through the laminated film. Therefore, it means that the smaller the numerical value is, the easier it is to pass through, and the higher numerical value is, the more difficult it is to pass. That is, the smaller the value means that the communication in the thickness direction of the laminated film is better, and the larger the value means that the communication in the thickness direction of the laminated film is worse. Communication is the degree of connection of holes in the thickness direction of the laminated film.
By setting the air permeability of the first main film to 1000 seconds / dL or more, air communication in the thickness direction of the film is lowered, so that the laminated film is excellent in heat insulation. By having a layer (II) described later, it becomes easy to obtain a film having an air permeability in the above range. When the adhesive film or adhesive is applied to form the adhesive layer or the adhesive layer on the layer (II) because the laminated film has the layer (II), adhesion to the porous layer (I) portion Intrusion of the adhesive or the pressure-sensitive adhesive can be prevented, and a decrease in heat insulation can be suppressed.
From the same viewpoint as the first main film, the second main film also has an air permeability of preferably 1000 seconds / dL or more, more preferably 5000 seconds / dL or more, and 10,000 seconds / dL. It is still more preferable that it is above.
The air permeability (seconds / 100 ml) can be measured according to JIS P8117, and specifically can be measured by the method described in the examples.

(2) Porosity The porosity of the film is an important factor for defining the porous structure, and is a numerical value indicating the ratio of the space portion of the porous layer in the film. In general, it is known that the higher the porosity, the better the heat insulating property. In the present invention, the porosity of the first main film is 50% or more, preferably 55% or more, more preferably. Is 60% or more. If the porosity is 50% or more, a laminated film having excellent heat insulation can be obtained.
From the same viewpoint as the first main film, the second main film also preferably has a porosity of 50% or more, more preferably 55% or more, and further preferably 60% or more. Is not particularly defined, but both the first and second main films are usually 75% or less.
The method for measuring the porosity is as follows.
The substantial amount W1 of the measurement sample is measured, and the mass W0 when the porosity is 0% is calculated based on the density of the resin composition constituting the film, and the porosity is calculated based on the following formula from these values. Is calculated.
Porosity (%) = {(W0−W1) / W0} × 100

Moreover, the porosity before and behind application | coating of an adhesive agent or an adhesive is the porosity P1 (%) of a laminated | multilayer film, and the void | hole of this film part after apply | coating an adhesive or an adhesive to one side of a laminated | multilayer film. From the rate P2 (%), it is preferable to satisfy the following formula (2).
Formula (2): P1-P2 <3
If the porosity change is less than 3%, the penetration of the adhesive or the pressure-sensitive adhesive into the laminated film is suppressed, and a decrease in heat insulation can be reduced.
The porosity of the first main film is 50% or more, and the first main film has a large number of pore structures. Most of the pore structure is present in the porous layer.

In order to obtain the porosity P1, P2 defined by the present invention, there are the following methods. A resin film (this film) having the layer (II) on at least one surface of the porous layer (I) is produced, and the porosity P1 is calculated for this film. Thereafter, an adhesive or pressure-sensitive adhesive is applied to the resin film using a coating device such as a bar coater and dried, and then a PET film is pasted to obtain a measurement sample. On the other hand, an adhesive or a pressure-sensitive adhesive is applied on a PET film by the same method as in the measurement sample preparation and dried to obtain a comparative sample. By calculating the difference in mass between the comparative sample and the measurement sample, the substantial amount W2 of the present film portion is calculated. The mass W0 when the porosity is 0% is calculated based on the density of the resin composition constituting the resin film, and the porosity P2 is calculated based on the following formula from these values.
Porosity (%) = {(W0−W2) / W0} × 100
However, the laminated film coated with adhesive or pressure-sensitive adhesive can be obtained by wiping off the surface adhesive or pressure-sensitive adhesive with an organic solvent, etc., and further removing the adhesive or pressure-sensitive adhesive by dipping in an organic solvent. The porosity P2 is calculated for the laminated film obtained by calculating the porosity P1 for the resin film and further applying an adhesive or pressure-sensitive adhesive to the resin film, by the method using the PET film described above. Can be calculated.
In the present invention, the change in porosity can be measured by any measurement method.

(3) a porous layer porous layer constituting the abundance ratio second of the film holes of (I) (I), the porous layer (I) abundance ratio of the open area 3 [mu] m ² or more at a hole in the cross section of the (N _A , Pieces / 100 μm ² ) is the formula (1).
Formula (1): N _A ≦ 1
N _A is preferably 0.5 pieces / 100 μm ² or less (N _A ≦ 0.5), more preferably 0.25 pieces / 100 μm ² or less (N _A ≦ 0.25), and 0 pieces. / 100 μm ² (N _A = 0) is particularly preferable.
By abundance ratio of the porous layer (I) of at open area 3 [mu] m ² or more in the cross section hole is one / 100 [mu] m ² or less, to suppress the generation of coarse pore size leading to deterioration of holes heat transfer, the film It can have excellent heat insulation.
From the same viewpoint as the first main film, the porous layer (I) constituting the first main film also has a pore abundance ratio (N _A , pieces having a pore area of 3 μm ² or more in the cross section of the porous layer (I). / 100 μm ² ) preferably satisfies the formula (1). In the first aspect of the film, the _{N A} is preferably from 0.5 pieces / 100 [mu] m ² or less _{(N A} ≦ 0.5), 0.25 units / 100 [mu] m ² or less _{(N A} ≦ 0.25) And more preferably 0/100 μm ² (N _A = 0).

The abundance ratio of pores having a pore area of 3 μm ² or more in the cross section of the porous layer (I) is measured by the following method.
With a scanning electron microscope (SEM) (“S-4500 manufactured by Hitachi High-Technologies Corporation”), it is visually confirmed that the porous layer (I) and the layer (II) are formed from the cross-sectional image of the porous film. The porous layer (I) is confirmed, and image processing is performed using image analysis software “SPIP (version 6.6.4)” manufactured by Image Metrology. As an image processing method, the detection method is set as a threshold, the detection is set as a hole, the threshold type is set as a fixed level, the hole threshold level is set as 80 Arbitrary, and the area is selected in the output without defining the hole range by a filter. After measuring the area of each hole, the ratio of holes having a hole area of 3 μm ² or more in the cross section of the porous layer (I) is calculated.

(4) Thickness The thickness of the film is not particularly limited, but is preferably 1 μm or more, more preferably 10 μm or more, and further preferably 20 μm or more. On the other hand, the upper limit is preferably 300 μm or less, more preferably 200 μm or less, and particularly preferably 150 μm or less. If thickness is 1 micrometer or more, Preferably it is 10 micrometers or more, it has a sufficient air layer in a porous layer, and can ensure heat insulation. Further, if the thickness is 300 μm or less, it can be used easily for applications that are used in a limited space where the installation place is narrow.

(5) Thermal conductivity The thermal conductivity is an important factor for defining the heat insulating material, and is one of the indexes of the heat insulating performance in this film. In this film, the thermal conductivity is preferably less than 0.025 (W / mK), more preferably less than 0.023 (W / mK), still more preferably less than 0.021 (W / mK). is there. When the thermal conductivity is less than 0.025 (W / mK), a laminated film having excellent heat insulation is obtained.
If the film satisfies the above “abundance ratio of pores of the porous layer” or “porosity”, it is easy to obtain a film having a thermal conductivity in the above range.
Here, the measurement method of thermal conductivity is as follows.
The film is cut into 10 mm squares, and the thickness is measured with a micrometer. After blackening with a graphite spray, the thermal diffusivity is evaluated using a xenon flash method (manufactured by NETZSCH, model: LFA447 nanoflash). The thermal conductivity is obtained from the product of the bulk density calculated from this value and the mass and the specific heat measured by a differential scanning calorimeter (DSC Pyris 1 manufactured by Perkin Elmer).

In the laminated film of the present invention, both the first main film and the second main film are made of propylene on at least one side of the porous layer (I) containing the propylene resin (A) as a main component and the porous layer (I). It is a laminated structure having a layer (II) mainly composed of a resin (B).
When the layer (II) is provided on at least one surface of the porous layer (I), the adhesive layer or the pressure-sensitive adhesive layer is applied to the surface of the layer (II) to form the adhesive layer or the pressure-sensitive adhesive layer. Since the pore structure is not blocked, the heat insulation can be prevented from lowering, so that the laminated film has excellent workability. So to speak, the layer (II) functions as a protective layer for protecting the pores of the porous layer (I) from being blocked.

The layer structure of the laminated film of the present invention is not particularly limited, and the porous layer (I) mainly composed of the propylene resin (A) and the layer (II) mainly composed of the propylene resin (B). In addition to the two-layer configuration, a multi-layer configuration of three layers, four layers, five layers, or more may be used. Regardless of the layer structure, if the porous layer (I) has the layer (II) on at least one side, it has excellent heat insulation, and an adhesive or pressure-sensitive adhesive is applied to the surface of the protective layer (II). In particular, since it is possible to suppress a decrease in heat insulation, a laminated film having excellent workability is obtained.
In particular, as shown in (II) / (I) / (II), the porous layer (I) is arranged in the intermediate layer, and the layer (II) is arranged in the front and back layers of the porous layer (I). ) Can be formed as pseudo independent pores, so that liquid permeation into the porous layer (I) does not occur, and excellent heat insulation is provided to prevent gas convection. Therefore, it can be said that the laminated film of the present invention is a laminated heat insulating film.

The ratio of the thickness of each layer (laminate ratio) of the laminated film of the present invention is not particularly limited.
The thickness ratio between the porous layer (I) and the layer (II) in the laminated film of the present invention can be appropriately adjusted according to the application and purpose.
From the viewpoint of obtaining the effect of the present invention, the thickness ratio [(I) :( II)] between the porous layer (I) and the layer (II) is preferably 1: 1 to 1: 0.025, more preferably. Is 1: 0.5 to 1: 0.05. When the thickness ratio between the porous layer (I) and the layer (II) is in the above range, the balance between the heat insulating properties and the mechanical properties is good, and it is particularly suitable for use as a heat insulating film. In addition, when there are two or more porous layers (I), the “thickness of the porous layer (I)” refers to the total thickness of the plurality of porous layers (I). The same applies to layer (II).
Adjustment of the thickness and thickness ratio of the porous layer (I) and the layer (II) in the laminated film can be controlled by adjusting the thickness of the nonporous film-like material before stretching, stretching conditions, and the like.
The lamination ratio of the porous layer (I) with respect to the total thickness is preferably 50% or more and 97% or less, more preferably 55% or more and 96% or less, and further preferably 60% or more and 95% or less. The thickness of the porous layer (I) layer in the laminated film is preferably 5 to 290 μm, and more preferably 10 to 280 μm. If the thickness ratio of the porous layer (I) and the thickness in the film are within this range, the film can have excellent heat insulation properties.
Further, the lamination ratio of the layer (II) with respect to the total thickness is preferably 3% or more and 50% or less, more preferably 4% or more and 45% or less, and further preferably 5% or more and 40% or less. The thickness of the layer (II) in the laminated film is preferably 1 to 100 μm, and more preferably 2 to 95 μm. If the thickness ratio of the layer (II) and the thickness in the film are within this range, when the adhesive or adhesive is applied onto the layer (II), the penetration of the adhesive or adhesive is suppressed. The pores derived from the internal porous structure are maintained, and the heat insulating property does not deteriorate.
Here, when a plurality of porous layers (I) and (II) are arranged, the total thickness of each layer is used for calculation.

  This film should just be equipped with the said structure, and may further be provided with the other layer.

  Hereinafter, the porous layer (I) and the layer (II) (protective layer) constituting the film will be described. Then, the formation method of this film as a manufacturing method is demonstrated.

  Below, each component which comprises this film is demonstrated.

2. Porous layer (I)
The porous layer (I) constituting the laminated film of the present invention contains a propylene-based resin (A).
Hereinafter, each component which comprises a porous layer is demonstrated.

2-1. Propylene resin (A)
As the propylene-based resin (A) in the present invention, homopolypropylene (propylene homopolymer), or propylene and ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene or Examples thereof include random copolymers or block copolymers with α-olefins such as 1-decene. Among these, homopolypropylene is more preferably used from the viewpoint of mechanical strength.

  In addition, the propylene resin (A) preferably has an isotactic pentad fraction exhibiting stereoregularity of 80 to 99%, more preferably 83 to 98%, and still more preferably 85 to 97%. . If the isotactic pentad fraction is 80% or more, the mechanical strength is good. On the other hand, the upper limit of the isotactic pentad fraction is defined by the upper limit that can be obtained industrially at the present time, but this is not the case when a more regular resin is developed at the industrial level in the future. is not. The isotactic pentad fraction is a three-dimensional structure in which five methyl groups that are side chains are located in the same direction with respect to the main chain of carbon-carbon bonds composed of arbitrary five consecutive propylene units. Or the ratio is meant. Signal assignment of the methyl group region is as follows. Zambelli et al. (Macromol. 8, 687 (1975)).

  Moreover, it is preferable that Mw / Mn which is a parameter which shows molecular weight distribution of propylene-type resin (A) is 1.5-10.0. More preferably, it is 2.0-8.0, More preferably, it is 2.0-6.0. This means that the smaller the Mw / Mn, the narrower the molecular weight distribution. By setting the Mw / Mn to 1.5 or more, sufficient extrudability can be obtained, and industrial mass production is possible. On the other hand, by setting Mw / Mn to 10.0 or less, sufficient mechanical strength can be ensured. Mw / Mn is measured by a GPC (gel per emission chromatography) method.

  Further, the melt flow rate (MFR) of the propylene-based resin (A) is not particularly limited, but usually the MFR is preferably 0.5 to 15 g / 10 minutes, and preferably 1.0 to 10 g / 10. More preferably, it is minutes. By setting the MFR to 0.5 g / 10 min or more, it has a sufficient melt viscosity at the time of molding and can ensure high productivity. On the other hand, by setting the MFR to 15 g / 10 min or less, sufficient strength can be ensured. MFR is measured under the conditions of a temperature of 230 ° C. and a load of 2.16 kg in accordance with JIS K7210-1 (2014).

  In addition, the manufacturing method of propylene-type resin (A) is not specifically limited, The well-known polymerization method using the well-known polymerization catalyst, for example, the multisite catalyst represented by the Ziegler-Natta type | mold catalyst, a metallocene catalyst Examples thereof include a polymerization method using a single site catalyst typified by the above.

  Examples of the propylene-based resin (A) include, for example, trade names “Novatech PP” “WINTEC” (manufactured by Nippon Polypro), “Versify” “Notio” “Toughmer XR” (manufactured by Mitsui Chemicals), “Zeras”, “Thermo Run”. (Mitsubishi Chemical Co., Ltd.), “Sumitomo Noblen” “Tough Selenium” (Sumitomo Chemical Co., Ltd.), “Prime Polypro” “Prime TPO” (Prime Polymer Co., Ltd.), “Adflex” “Adsyl” “HMS-PP (PF814)” Commercially available products such as “Sun Aroma” and “Inspire” (Dow Chemical) can be used.

  The porous layer (I) can be obtained, for example, by stretching a nonporous film-like material composed of a resin composition containing as a main component a propylene-based resin (A) containing a large amount of β crystals, which is one of crystal forms. In the formation of a porous structure using β crystals, since the β crystals in the propylene-based resin are converted into α crystals during the stretching process, the porous structure is dense and the conventionally known inorganic filler, non- Compared to the formation of a porous structure by adding a compatible organic substance or the like, it is advantageous for the preparation of a porous structure because it does not depend on the particle diameter, dispersion diameter, or the like.

  The β crystal activity of the porous layer (I) can be regarded as an index indicating that the propylene-based resin produced β crystals in the non-porous film-like material before stretching. If the propylene-based resin in the non-porous film-like material before stretching produces β-crystals, many fine and uniform pores are formed by subsequent stretching, so it has excellent mechanical properties and is fine and uniform. Excellent heat insulation can be obtained by forming the holes.

  The presence or absence of β crystal activity in the porous layer (I) is determined by performing differential thermal analysis of the porous layer (I) using a differential scanning calorimeter and detecting the crystal melting peak temperature derived from the β crystal of the propylene resin. It is judged by whether or not it is done. Specifically, the laminated film is heated from 25 ° C. to 240 ° C. at a heating rate of 10 ° C./min for 1 minute, and then cooled from 240 ° C. to 25 ° C. at a cooling rate of 10 ° C./min. When the temperature is lowered for 1 minute and then heated again from 25 ° C. to 240 ° C. at a heating rate of 10 ° C./min, the crystal melting peak temperature (Tmβ) derived from the β crystal of the propylene resin at the time of reheating is If detected, it is determined to have β crystal activity.

  The presence or absence of the β crystal activity can also be determined by a diffraction profile obtained by X-ray diffraction measurement of a laminated film subjected to a specific heat treatment. Specifically, the heat treatment at 170 to 190 ° C., which exceeds the crystal melting peak temperature of the propylene-based resin, is performed and slowly cooled to form β crystals, and the grown porous film (I) of the laminated film is subjected to X-rays. When diffraction measurement is performed and a diffraction peak derived from the (300) plane of the β crystal of the propylene-based resin is detected in the range of 2θ = 16.0 ° to 16.5 °, it is determined that there is β crystal activity. . For details on the β crystal structure and X-ray diffraction measurement of the propylene resin, see Macromol. Chem. 187, 643-652 (1986), Prog. Polym. Sci. Vol. 16, 361-404 (1991), Macromol. Symp. 89, 499-511 (1995), Macromol. Chem. 75, 134 (1964), and references cited therein.

  As a method for obtaining the β crystal activity of the porous layer (I) described above, a method in which a substance that promotes the formation of α crystal of the propylene resin is not added to the resin composition constituting the porous layer (I), Patent No. A method of adding a propylene-based resin that has been treated to generate peroxide radicals as described in Japanese Patent No. 3739481, and a β-crystal nucleating agent is added to the resin composition constituting the porous layer (I) The method etc. are mentioned. Among them, it is particularly preferable to obtain a β crystal activity by adding a β crystal nucleating agent to the resin composition constituting the porous layer (I). By adding a β crystal nucleating agent, the production of β crystals of a propylene resin can be promoted more uniformly and efficiently, and a laminated film having a porous layer (I) having β crystal activity can be obtained. it can.

  The porous layer (I) contains the propylene resin (A) as a main component, and the content thereof is 50% by mass or more, preferably 70 to 99.9999% by mass, more preferably 80 to 99.999% by mass, and still more preferably. It is 90-99.99 mass%.

2-2. β-crystal nucleating agent The first present film has β-crystal activity, and the porous layer (I) of the first present film has a fine porous structure. The second main film also preferably has the β crystal activity in order that the porous layer (I) has a fine porous structure. In both the first main film and the second main film, the porous layer (I) preferably contains a β-crystal nucleating agent. Examples of the β crystal nucleating agent used in the present invention include the following, but are not particularly limited as long as they increase the generation and growth of β crystals of the propylene resin, and two or more types are mixed and used. May be.

Examples of the β crystal nucleating agent include amide compounds; tetraoxaspiro compounds; quinacridones; iron oxides having a nanoscale size; potassium 1,2-hydroxystearate, magnesium benzoate or magnesium succinate, magnesium phthalate, etc. Alkali metal salts or alkaline earth metal salts of carboxylic acids represented by: aromatic sulfonic acid compounds represented by sodium benzenesulfonate or sodium naphthalenesulfonate; di- or triesters of dibasic or tribasic carboxylic acids; Phthalocyanine pigments typified by phthalocyanine blue, etc .; two-component compounds consisting of component A, which is an organic dibasic acid, and component B, which is an oxide, hydroxide or salt of a Group 2 metal in the periodic table; cyclic phosphorus compounds And magnesium compound Such as the formation thereof.
Among these, one or more selected from the group consisting of amide compounds, tetraoxaspiro compounds, and quinacridones are preferable.

  Specific examples of commercially available β crystal nucleating agents include β crystal nucleating agent “NJESTER NU-100” manufactured by Shin Nippon Rika Co., Ltd., and specific examples of propylene resins to which β crystal nucleating agents are added include Aristech. Examples include polypropylene “Bepol B-022SP”, Borealis polypropylene “Beta (β) -PP BE60-7032,” Mayzo polypropylene “BNX BETAPP-LN”, and the like.

  The content of the β-crystal nucleating agent in the porous layer (I) can be appropriately adjusted depending on the type of the β-crystal nucleating agent or the composition of the propylene-based resin, but 100 mass of the propylene-based resin in the porous layer (I). 0.0001-5.0 mass parts is preferable with respect to part, 0.001-3.0 mass parts is more preferable, and 0.01-1.0 mass part is further more preferable. If it is 0.0001 part by mass or more, β-crystals of propylene resin can be generated and grown sufficiently at the time of production, sufficient β-crystal activity can be secured, and sufficient β-crystal activity can be secured even when a laminated film is formed. The desired heat insulating properties can be obtained. On the other hand, addition of 5.0 parts by mass or less is preferable because it is economically advantageous and there is no bleeding of the β crystal nucleating agent on the film surface.

3. Layer (II) (Protective layer)
The layer (II) (protective layer) in the laminated film of the present invention is a layer that does not soak when a solvent is dropped on its surface.
Preferably, the protective layer (II) is observed with a scanning electron microscope (SEM) (“S-4500, Hitachi High-Technologies Corporation”), and image analysis software “SPIP (version 6.6. 4) ”as the image processing method, the detection method is set as a threshold, the detection is set as a hole, the threshold type is set as a fixed level, the hole threshold level is set as 80 Arbitrary, and the output is performed without defining the hole range by a filter. It is preferable that the layer (II) has no pores of 1 μm ² or more. By being such a layer (II), the penetration of the pressure-sensitive adhesive is suppressed, the pores derived from the internal porous structure are maintained, and the heat insulating property does not deteriorate.

3-1. Propylene resin (B)
The propylene-based resin (B) in the present invention is preferably a propylene-based resin described in the above-mentioned propylene-based resin (A), and is particularly preferably a random propylene-based resin from the viewpoint of hardly generating a porous structure. By selecting a random propylene-based resin for the layer (II), it is possible to make it difficult to form voids (holes) during stretching that occur when a homopropylene-based resin, a block propylene-based resin, or the like is selected. Moreover, when apply | coating an adhesive, the penetration | invasion of the adhesive to a porous layer can be suppressed and a heat insulation fall can be prevented.

  Layer (II) contains propylene resin (B) as a main component, and its content is 50% by mass or more, preferably 70 to 99.9999% by mass, more preferably 80 to 99.999% by mass, and still more preferably 90%. ˜99.99 mass%.

  Each layer constituting this film has additives that do not impair its properties, such as heat stabilizers, antioxidants, ultraviolet absorbers, light stabilizers, crystal nucleating agents, colorants, antistatic agents, and hydrolysis inhibitors. Various additives such as an agent, a lubricant, a flame retardant, and an elastomer may be appropriately included. Moreover, other resin compositions may be contained to such an extent that the property is not impaired.

4). Manufacturing method of laminated film The manufacturing method of the laminated film of the present invention will be described. The following description is an example of a method of manufacturing the laminated film of the present invention, and the laminated film of the present invention is manufactured by such a manufacturing method. It is not limited to a laminated film.

  A method for producing a laminated film according to an example of an embodiment of the present invention (hereinafter sometimes referred to as “the film production method”) includes a layer containing a propylene resin (A) as a main component and a β crystal nucleating agent (C). Forming a non-stretched film having (i) and a layer (ii) mainly composed of the propylene-based resin (B) on at least one side of the layer (i), and stretching the unstretched film A stretching process for creating a stretched film.

  This film manufacturing method should just be equipped with the said process, and may further be provided with another process, a process, etc.

Moreover, in this invention, in the range which does not impair the effect of this invention, components other than propylene resin (A), propylene resin (B), and (beta) crystal nucleating agent (C), for example, propylene polymer (A It is permissible to mix other resins other than).
Other resins include polystyrene resins, polyvinyl chloride resins, polyvinylidene chloride resins, chlorinated polyethylene resins, polyester resins, polycarbonate resins, polyamide resins, polyacetal resins, acrylic resins, ethylene acetate Vinyl copolymer, polymethylpentene resin, polyvinyl alcohol resin, cyclic olefin resin, polylactic acid resin, polybutylene succinate resin, polyacrylonitrile resin, polyethylene oxide resin, cellulose resin, polyimide resin , Polyurethane resin, polyphenylene sulfide resin, polyphenylene ether resin, polyvinyl acetal resin, polybutadiene resin, polybutene resin, polyamideimide resin, polyamide bismaleimide resin, Arylate resins, polyether imide resins, polyether ether ketone resin, polyether ketone resin, polyether sulfone resin, polyketone resin, polysulfone resin, aramid-based resin, fluorine-based resins.

  In the present invention, in addition to the components described above, additives that are generally blended can be added as appropriate within a range that does not significantly impair the effects of the present invention. Examples of the additive include recycled resin generated from trimming loss of ears and the like, silica, talc, kaolin, carbonic acid, which are added for the purpose of improving or adjusting molding processability, productivity and various physical properties of the porous film. Inorganic particles such as calcium, pigments such as titanium oxide and carbon black, flame retardants, weathering stabilizers, heat stabilizers, antistatic agents, melt viscosity improvers, crosslinking agents, lubricants, nucleating agents, plasticizers, anti-aging agents , Antioxidants, light stabilizers, ultraviolet absorbers, neutralizers, antifogging agents, antiblocking agents, slip agents, colorants and the like.

  When kneading, the machine to be used is not particularly limited. For example, a known extruder such as a single screw extruder, a twin screw extruder, or a multi-screw extruder can be used. Further, depending on the equipment structure and necessity, a pressure reducer may be connected to the vent port to remove moisture and low molecular weight substances.

  Hereinafter, the film forming process and the stretching process will be sequentially described.

(1) Film-forming process Examples of a method for heating and melting the material resin include a T-die method and an inflation method. Among these, the T-die method is preferably employed. Practically, it is preferable that the material resin is melt-extruded from a T-die and cast by a cast roll.

  When adopting the T-die method as a specific method for forming a film, a sheet-like molten resin extruded from the T-die is laminated and adhered onto a rotating cast roll (chill roll, cast drum). The method of shape | molding in a take-off sheet-like material can be mentioned.

A touch roll, an air knife, an electric contact device or the like may be attached to the cast roll in order to bring the film-like material into close contact with the cast roll.
When forming the film while cooling the kneaded product, the temperature of the cast roll is preferably 100 ° C. or higher. More preferably, it is 110 degreeC or more, More preferably, it is 120 degreeC or more. In the present invention, the porosity of the cast roll can be increased by 100 ° C. or higher because the porosity can be increased by the opening of the crystalline portion and the amorphous portion of the propylene-based resin in the porous layer (I) by the stretching step. Thus, it is preferable to obtain a laminated non-porous film having a high crystallinity.

In the obtained unstretched film, the thickness of the effective portion excluding both ends is preferably 50 μm to 1000 μm, more preferably 80 μm or more and 800 μm or less, and particularly preferably 100 μm or more or 600 μm or less.
If the unstretched film thickness is 50 μm or more, the film is too thin to prevent breakage during stretching. If the unstretched film thickness is 1000 μm or less, the film becomes too rigid. It is possible to prevent the stretching from becoming difficult.

  Regarding the layer structure in the raw film of the laminated film of the present invention, not only the layer structure described above but also a combination of other layers may be used.

In the unstretched film, the ratio (T2 / T1) of the thickness (T2) of the layer (II) to the thickness (T1) of the porous layer (I) preferably satisfies the relationship of 0.05 to 1.0. When the thickness ratio is within this range, a film excellent in heat insulation even in the case of a thin film and excellent in workability that does not cause deterioration in heat insulation even when an adhesive or a pressure-sensitive adhesive is applied can be obtained. It is done.
Here, when a plurality of layers (I) and (II) are arranged, the total thickness of each layer is used for calculation.

  The unstretched film preferably has a layer (I) having a thickness of 50 to 600 μm. The lower limit of this thickness is more preferably 55 μm, still more preferably 60 μm. On the other hand, the upper limit is more preferably 580 μm, still more preferably 550 μm. The laminated film which has favorable heat insulation is obtained because the thickness of layer (I) is 50 micrometers or more. On the other hand, when the thickness of the layer (I) is 600 μm or less, a laminated film having a thickness of 300 μm or less after stretching can be obtained.

  The unstretched film preferably has a layer (II) having a thickness of 5 to 300 μm. The lower limit of this thickness is more preferably 10 μm and even more preferably 20 μm. On the other hand, the upper limit is more preferably 250 μm, and still more preferably 200 μm. By having the layer (II) of 5 μm or more, the porous layer can be closed after stretching, and a laminated film having a protective layer is obtained. On the other hand, the laminated film which suppressed the heat insulation fall is obtained because it is 300 micrometers or less layer (II).

(2) Stretching process Next, the obtained nonporous film-like material is subjected to uniaxial stretching or biaxial stretching. Uniaxial stretching may be longitudinal uniaxial stretching or transverse uniaxial stretching. Biaxial stretching may be simultaneous biaxial stretching or sequential biaxial stretching. In the case of producing a laminated film having a protective layer, which is the object of the present invention, sequential biaxial stretching is more preferred because the stretching conditions can be selected in each stretching step and the porous structure can be easily controlled. In addition, extending | stretching to the flow direction (MD) of a film-like thing is called "longitudinal stretching", and extending | stretching to the orthogonal | vertical direction (TD) with respect to a flow direction is called "lateral stretching."

  When using sequential biaxial stretching, the stretching temperature needs to be selected in a timely manner according to the composition of the resin composition to be used, the crystal melting peak temperature, the crystallinity, etc., but the control of the porous structure is relatively easy, the mechanical strength, It is easy to balance with other physical properties such as shrinkage.

  The longitudinal stretching temperature is preferably 60 to 140 ° C, more preferably 80 to 120 ° C. It is preferable to set the longitudinal stretching temperature to 140 ° C. or lower because stretching can be performed without breaking below the melting point of the main component propylene resin. On the other hand, since it can suppress the fracture | rupture at the time of extending | stretching by setting it as 60 degreeC or more, it is preferable.

  The longitudinal stretching ratio can be arbitrarily selected, but the stretching ratio per uniaxial stretching is preferably 1.1 to 10 times, more preferably 1.5 to 8.0 times, and still more preferably 1.5 to 6. 0 times. When the stretch ratio per uniaxial stretching is 1.1 times or more, whitening proceeds and sufficient porosity is achieved by stretching. Moreover, by setting it as 10 times or less, the deformation | transformation of a void | hole is suppressed and the laminated | multilayer film fully whitened can be obtained.

  The transverse stretching temperature is preferably 100 to 160 ° C, more preferably 110 to 150 ° C. When the transverse stretching temperature is within the specified range, the pores generated during the longitudinal stretching can be expanded to increase the porosity of the porous layer, and thus sufficient heat insulation can be achieved.

  The transverse draw ratio can be arbitrarily selected, but is preferably 1.1 to 10 times, more preferably 1.5 to 9.0 times, and still more preferably 1.5 to 8.0 times. By stretching at a prescribed transverse stretching ratio, it is possible to have a sufficient porosity without deforming pores generated during longitudinal stretching.

  Furthermore, the laminated film of the present invention can be subjected to surface treatment such as corona treatment, plasma treatment, printing, coating, vapor deposition, and further perforation as necessary within the range not impairing the present invention. Depending on the situation, it is possible to stack several laminated films of the present invention.

5. Applications The laminated film of the present invention can easily impart heat insulation to various members by applying a pressure-sensitive adhesive or an adhesive to the protective layer and combining it with other members. Used as a member of electronic equipment.

  Examples of the base polymer (or base elastomer) used in the composition of the pressure-sensitive adhesive applied to one side of the laminated film in the present invention include natural rubber, synthetic isoprene, styrene-isoprene-styrene block copolymer (SIS), and styrene-butadiene. -Styrene block copolymer (SBS), SBS hydrogenated styrene-ethylene / butylene-styrene triblock copolymer (SEBS), SI hydrogenated styrene-ethylene / propylene block copolymer (SEP), SIS Rubber adhesives mainly composed of styrene-ethylene / propylene-styrene block copolymer (SEPS) hydrogenated, acrylic acid esters such as 2-ethylhexyl acrylate or butyl acrylate, or methacrylic acid esters. Polymerized And it is appropriately selected from an acrylic adhesive.

  In order to obtain higher adhesive strength, the pressure-sensitive adhesive is alicyclic petroleum resin, aliphatic petroleum resin, terpene resin, ester resin, coumarone-indene resin, rosin resin, An epoxy resin, a phenol resin, an acrylic resin, a butyral resin, an olefin resin, a chlorinated olefin resin, a vinyl acetate resin, and a tackifier mainly composed of these modified resins or hydrogenated resins, liquid isoprene, liquid butadiene, Liquid butadiene / isoprene, liquid styrene / butadiene, liquid styrene / isoprene, polybutene, polyisobutylene, liquid terpene, liquid rosin, paraffin oil, plasticizers, isocyanate crosslinkers, epoxy crosslinkers, amine crosslinks Agent, melamine crosslinking agent, aziridine crosslinking agent, hydrazine Crosslinking agent, aldehyde-based crosslinking agents, oxazoline crosslinking agents, metal alkoxide crosslinking agents, metal chelate crosslinking agents, metal salt crosslinking agent, a crosslinking agent may be added mainly of ammonium salt-based crosslinking agent. These other components can be used alone or in combination of two or more.

  Solvents used for preparing the adhesive include aromatic hydrocarbon solvents such as benzene and toluene; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; n-pentane, n -Aliphatic hydrocarbon solvents such as hexane and n-heptane; Alicyclic hydrocarbon solvents such as cyclopentane and cyclohexane; and the like. These solvents can be used alone or in combination of two or more.

6). Laminated body for image display apparatus, image display apparatus The laminated body for image display apparatus of the present invention has a touch panel, an image display panel, a surface protection panel, a retardation film, a polarizing film, a color filter on at least one side of the laminated film of the present invention. And any one or more selected from the group consisting of flexible substrates.
The image display device of the present invention is provided with the laminate for an image display device of the present invention.
An image display device including members for an image display device such as a touch panel, an image display panel, a surface protection panel, a retardation film, a polarizing film, a color filter, and a flexible substrate is generally easily heated and functions by heat generation. May decrease.
The laminated film of the present invention is excellent in heat insulation and processability even if it is a thin film. Therefore, it is easy to be bonded to a member for an image display device and an image display device, and the weight of the member for an image display device and the image display device. It is possible to perform heat insulation while suppressing the reduction of the function, and it is possible to suppress the functional deterioration of the image display device member and the image display device.

  Examples and Comparative Examples are shown below, and the laminated film of the present invention will be described in more detail. However, the present invention is not limited at all.

<Porous layer (I)>
(Propylene resin (A))
A-1: Homopolypropylene (Novatech PP FY6HA, MFR: 2.4 g / 10 min [230 ° C., 2.16 kg load], Mw / Mn = 3.2, manufactured by Nippon Polypro Co., Ltd.)
(Β crystal nucleating agent)
C-1; 3,9-bis [4- (N-cyclohexylcarbamoyl) phenyl] -2,4,8,10-tetraoxaspiro [5,5] undecane
(Antioxidant)
D-1; tris (2,4-di-t-butylphenyl) phosphite and tetrakis [3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionic acid] pentaerythritol 1: 1 mixture (IRGANOX-B225, manufactured by BASF)
(Elastomer)
E-1: Styrene-ethylene / propylene-styrene block copolymer (SEPS, SEPTON 2005, MFR: not flowing, manufactured by Kuraray Co., Ltd.)

<Layer (II)>
(Propylene resin (B))
B-1: random polypropylene (Prime TPO F3910, MFR: 4.5 g / 10 min, manufactured by Prime Polymer Co., Ltd.)

Example 1
100 parts by mass of propylene-based resin (A-1), 0.2 part by mass of β crystal nucleating agent (C-1) and 0.1 part by mass of antioxidant (D-1) are mixed and mixed in a twin screw extruder. The mixture 1 was obtained by melt extrusion at 280 ° C. Using a T-die with a lip opening of 1 mm, molding is performed using propylene-based resin (B-1) for the front and back layer side extruder and the mixture 1 for the middle layer side extruder, guided to the cast roll, and laminated non-porous film-like material (Unstretched film) was obtained. The thickness of the surface layer [layer (II)] / intermediate layer [layer (I)] / back layer [layer (II)] of the laminated non-porous film (unstretched film) is “unstretched film” in Table 1. The thickness shown in the column “Layer (II) / Layer (I) / Layer (II) Thickness Ratio”. Thereafter, the laminated non-porous film-like material was longitudinally stretched by using a longitudinal stretching machine between rolls set at 105 ° C. with a draw ratio of 65% multiplied by 3 stages (longitudinal stretching ratio: 4.5 times). The film after longitudinal stretching was preheated at a preheating temperature of 150 ° C. and a preheating time of 12 seconds in a film tenter facility (manufactured by Kyoto Machine Co., Ltd.), and then stretched 3.5 times in the transverse direction at a stretching temperature of 150 ° C. Heat treatment was performed at 0 ° C. to obtain a laminated film. The evaluation results of the obtained laminated film are summarized in Table 1. Moreover, the cross-sectional image which image | photographed the cross section which cut | disconnected the obtained laminated | multilayer film in TD direction with the scanning electron microscope (SEM) is shown in FIG.

(Comparative Example 1)
Molding was performed using the mixture 1 with a T die having a lip opening of 1 mm, and the film was guided to a cast roll to obtain a nonporous film-like material. Thereafter, longitudinal stretching and lateral stretching were performed in the same manner as in Example 1 to obtain a laminated film. The evaluation results of the obtained laminated film are summarized in Table 1.

(Comparative Example 2)
With a T-die with a lip opening of 1 mm, propylene resin (B-1) is used for the front and back layer side extruder, 70% by mass of propylene resin (A-1) and 30% by mass of elastomer (E-1) are used for the middle layer side extruder. Molding was performed using the mixture, and the film was guided to a cast roll to obtain a laminated non-porous film. Thereafter, the laminated non-porous film-like material was stretched at a low temperature using a longitudinal stretching machine at a draw ratio of 50% (longitudinal stretching ratio 1.5 times) between a roll set at 20 ° C. and a roll set at 40 ° C. Went. Next, high-temperature stretching was performed between rolls set at 120 ° C. with a draw ratio of 100% (longitudinal stretching ratio: 2.0 times). The film after longitudinal stretching was stretched 3.5 times in the transverse direction in the same manner as in Example 1, and then a laminated film was obtained. The evaluation results of the obtained laminated film are summarized in Table 1. Moreover, the cross-sectional image which image | photographed the porous layer (I) part of the cross section which cut | disconnected the obtained laminated | multilayer film in TD direction with the scanning electron microscope (SEM) is shown in FIG.

(Comparative Example 3)
Using a T-die with a lip opening of 1 mm, the extruder was molded using propylene resin (A-1) to obtain a nonporous membrane. Then, the film was obtained by performing longitudinal stretch and lateral stretch by the method similar to Example 1. FIG. The evaluation results of the obtained film are summarized in Table 1.

  Regarding the films obtained in Examples and Comparative Examples, film thickness, porosity, pore abundance, air permeability, thermal conductivity, solvent soaking, and porosity after applying adhesive are as follows. It was measured.

(1) Film thickness About the unstretched film (laminated nonporous film-like material) and stretched film (laminated film) of Examples and Comparative Examples, 10 points were measured at random using a 1/1000 mm dial gauge. The average value was taken as the thickness.

(2) Porosity The actual amount W1 of the measurement sample is measured, the mass W0 when the porosity is 0% is calculated based on the density of the resin composition, and the porosity is calculated based on the following formula from these values. The rate was calculated.
Porosity (%) = {(W0−W1) / W0} × 100

(3) Abundance ratio of pores A cross section obtained by cutting a measurement sample in the TD direction was scanned with a porous layer (I) and a layer (II) using a scanning electron microscope (SEM) ("S-4500 manufactured by Hitachi High-Technologies Corporation"). ) Was visually confirmed. Regarding the porous layer (I), image processing was performed using image analysis software “SPIP (version 6.6.4)” manufactured by Image Metrology. As an image processing method, the detection method is set as a threshold, the detection is set as a hole, the threshold type is set as a fixed level, the hole threshold level is set as 80 Arbitrary, and the area is selected in the output without defining the hole range by a filter. After measuring the area of each pore, the abundance ratio (N _A ) of pores having a pore area of 3 μm ² or more in the porous layer (I) was calculated.
Table 1 shows that the abundance ratio (N _A ) satisfies the formula (1) (N _A ≦ 1) as “◯” and the abundance ratio (N _A ) as “x”.

(4) Air permeability at 25 ° C. In the air atmosphere at 25 ° C., the air permeability was measured according to JIS P8117. As a measuring instrument, a digital type Oken type air permeability dedicated machine (Asahi Seiko Co., Ltd.) was used.

(5) Thermal conductivity After cutting a measurement sample into 10 mm square and measuring the thickness with a micrometer, the sample was blackened with graphite spray, and then heated using a xenon flash method (manufactured by NETZSCH, model: LFA447 nanoflash). The diffusion rate was evaluated. The thermal conductivity was determined from the product of this value calculated from the size and mass, the bulk density, and the specific heat measured with a differential scanning calorimeter (DSC Pyris 1 manufactured by Perkin Elmer).

(6) Solvent soaking The following 3 types of solvents having different solubility parameters (SP values) were dripped into the measuring sample, and the solvent soaking into the measuring sample was visually evaluated. The evaluation criteria are specified below. For details regarding the SP value, values specified in the durability of the polymer material (Industry Research Committee, 1993) and the like were used as a reference.
(I) Normal hexane (Nacalai Tesque, concentration: 95.0% or more, SP value: 14.7)
(B) Acetone (Nacalai Tesque, concentration: 99.0% or more, SP value: 20.1)
(C) Ethanol (manufactured by Nacalai Tesque, concentration: 99.5% or more, SP value: 26.2)
○: Solvent remains on the surface and does not stain the film. ×: Solvent does not remain on the surface and causes the film to penetrate. Check that the solvent is dropped by dropping a solvent with a different SP value onto the measurement sample. Thus, with respect to the solvents within the above three SP value ranges, it is possible to easily confirm the presence or absence of permeation into the measurement sample.

(7) Porosity after application of adhesive (P2)
As a rubber component of the pressure-sensitive adhesive, 100% by mass of a styrene-based elastomer (styrene-ethylene / butylene-styrene block copolymer, grade name: SEPTON 8006, styrene content = 33%, MFR = non-flowing, manufactured by Kuraray Co., Ltd.) Liquid plastic isoprene resin (hydrogenated liquid isoprene rubber, Claprene LIR-290, number average molecular weight 31,000) as plasticizer and toluene (manufactured by Nacalai Tesque, concentration: 99.0% or more, SP value) as a diluent solvent : 18.2) was added so that it might become 12% of solid content concentration, and it mixed and prepared the adhesive for application | coating.
The prepared adhesive was applied to the measurement sample using a 50th bar coater, dried at 80 ° C. for 1 minute, and then a PET film (Mitsubishi Resin, Diafoil S100-50, thickness = 50 μm) was applied. The sample was pasted to obtain a measurement sample. The prepared pressure-sensitive adhesive was applied onto a PET film by the same method and dried to obtain a comparative sample. By subtracting the mass of the comparative sample from the mass of the measurement sample, the substantial amount W2 of the film portion was calculated. Based on the density of the resin composition constituting the film, the mass W0 when the porosity was 0% was calculated, and the porosity P2 was calculated from these values based on the following formula.
Porosity (%) = {(W0−W2) / W0} × 100
The penetration of the pressure-sensitive adhesive into the measurement sample was evaluated by comparison according to the following formula (2).
Formula (2): P1-P2 <3
○: Formula (2) is satisfied.
X: The formula (2) is not satisfied.

(8) β crystal activity The presence or absence of β crystal activity in each stretched film of the examples and comparative examples was analyzed using a differential scanning calorimeter.
Specifically, a differential scanning calorimeter (DSC Pyris 1 manufactured by Perkin Elmer) was used as follows. The temperature of the stretched film is raised from 25 ° C. to 240 ° C. at a heating rate of 10 ° C./min, and held for 1 minute, and then the temperature is lowered from 240 ° C. to 25 ° C. at a cooling rate of 10 ° C./minute and then held for 1 minute. β crystals were produced and grown. Furthermore, when the temperature of the stretched film is reheated from 25 ° C to 240 ° C at a heating rate of 10 ° C / min, the crystal melting peak temperature (145 to 160 ° C) derived from the β crystal of the propylene resin is detected at the time of reheating. Was determined to have β crystal activity.
Table 1 shows the stretched film having β crystal activity as ◯ and the stretched film not having β crystal activity as x.

  Table 1 shows the evaluation results regarding the examples and comparative examples.

Example 1 satisfies Formula (1), and there are few coarse pores in the porous layer (I), so that the thermal conductivity is reduced and the heat insulation is excellent. Furthermore, by having the layer (II), it is possible to suppress the change in porosity and to reduce the heat insulation property even when the adhesive is applied in combination with other members.
On the other hand, even in the case of Comparative Example 1 which has β crystal activity and satisfies the formula (I) but does not have the layer (II) (protective layer), it is difficult to uniformly apply at the time of application of the adhesive, and there is a concern about a decrease in heat insulation. The
In Comparative Example 2, since there is no β crystal activity, the formula (1) is not satisfied, and there are many coarse pores, the heat transfer of the holes is poor and the thermal conductivity is less than 0.025 (W / mK). There wasn't.
In the film having no β crystal activity of Comparative Example 3 and having no porous layer (I) and layer (II) (protective layer), no decrease in thermal conductivity is observed.

  The laminated film of the present invention can be widely used for various products such as precision equipment, home appliances, interiors of various vehicles, housing walls, ceilings, etc., which are greatly affected by temperature changes, and in particular, it can be thinned. Therefore, it can be expected to be used in the interior of various vehicles, where the installation space is limited, and in the field of mobile electronic devices.

Claims (6)

A porous layer (I) mainly composed of a propylene-based resin (A);
Having at least one side of the porous layer (I) with a layer (II) mainly composed of the propylene-based resin (B),
A laminated film having β crystal activity, an air permeability of 1000 seconds / dL or more, and a porosity of 50% or more. A porous layer (I) satisfying the formula (1) and mainly composed of the propylene-based resin (A);
A laminated film having a layer (II) mainly composed of a propylene-based resin (B) on at least one surface of the porous layer (I).
Formula (1): N _A ≦ 1
_{[N A} represents the abundance ratio of the porous layer (I) of at open area 3 [mu] m ² or more in a cross section hole (pieces / 100 [mu] m ^2). ]   The laminated film according to claim 1 or 2, wherein the thermal conductivity is less than 0.025 W / mK.   The laminated film according to any one of claims 1 to 3, wherein the thickness is 1 µm or more and 300 µm or less. At least one side of the laminated film according to any one of claims 1 to 4,
A laminate for an image display device, comprising at least one selected from the group consisting of a touch panel, an image display panel, a surface protection panel, a retardation film, a polarizing film, a color filter, and a flexible substrate.   An image display device provided with the laminate for an image display device according to claim 5.