JP7540306B2 - Laminated Film - Google Patents

Description

The present invention relates to a laminated film. Specifically, the present invention relates to a laminated film having a core layer and a skin layer, which is used, for example, as a protective film for a build-up film used in the manufacture of electronic components.

Polypropylene film is lightweight and has excellent thermal and mechanical stability, and is therefore widely used as an industrial material film, including for packaging. In recent years, in particular, taking advantage of the low surface energy of polypropylene film, it has been widely used as a protective material or release material in the manufacturing process for electronic components and electronic circuit boards, the manufacturing process for thermosetting resin components such as fiber-reinforced plastics, the manufacturing process for photosensitive films, and the like.

Patent No. 6354634 JP 2018-204002 A Patent No. 6341049 JP 2017-66395 A WO2018/079161

For example, polypropylene film is used as a protective film to protect the adhesive layer in build-up films used in the manufacture of electronic components, and is wound, stored, distributed, and used as a build-up film roll. The build-up film has a laminated structure in which a base film (such as a PET film), an adhesive layer (uncured or semi-cured thermosetting resin that serves as a sealant for electronic boards), and a protective film are laminated. In such build-up films, the adhesive layer (uncured or semi-cured thermosetting resin) is soft in the winding process after the protective film is laminated on the adhesive layer applied to the base film, so that if the winding tension is increased, the adhesive layer is likely to protrude from the end face of the roll. For this reason, in the winding process, the film is wound with a low winding tension so that the thermosetting resin does not protrude. This causes a problem that, in the transport process of the roll of the build-up film, the protective film (polypropylene film) and the base film contained in the roll are likely to become misaligned due to vibrations of the conveyor, etc.

In addition, in order to improve the processability of polypropylene films, it is common to add antiblocking agents to adjust frictional force. However, polypropylene films used in build-up films have the potential to affect the insulating performance of the thermosetting resin (insulating material that seals electronic substrates) that they come into contact with, so there are limitations on the addition of antiblocking agents and the like. Specifically, if the polypropylene film surface is made uneven by adding an antiblocking agent, when the polypropylene film (protective film) is peeled off from the thermosetting resin, the antiblocking agent present on the polypropylene film surface may fall off and transfer to the thermosetting resin. The thermosetting resin layer thickness becomes thinner in the area where the antiblocking agent has transferred to the thermosetting resin surface than in other areas, and this may cause a decrease in insulating performance. For this reason, there are limitations on the addition of fine particles such as antiblocking agents to polypropylene films used in build-up films.

As a polypropylene film that is given appropriate winding properties without blending an antiblocking agent, for example, a film containing polypropylene and a polyolefin other than polypropylene and having an appropriate roughness on the film surface due to the compatibility of the resins is known (Patent Document 1). It is considered that such a polypropylene film is suitable for processability as a work-in-progress. However, when the film described in Patent Document 1 is used as a protective film for a build-up film, the roughening of the film surface makes it difficult for winding misalignment to occur due to a decrease in the contact area with the opposing base film (PET film, etc.) caused by air entrainment during winding. On the other hand, when the film surface is roughened, the actual contact area with the opposing base film (PET film, etc.) that has high smoothness is reduced, so there is a problem that winding misalignment is likely to occur between the protective film (polypropylene film) and the base film (PET film, etc.) due to vibration during transport of the roll wound as a build-up film.

In addition, as a method for preventing the winding slippage of a build-up film roll, for example, a laminated film is known that includes a core layer and a skin layer laminated on at least one side of the core layer, and the ethylene content in the skin layer is adjusted within a predetermined range to suppress the winding slippage between the build-up film roll and the opposing base film (PET film, etc.) (Patent Document 2). However, in the laminated film described in Patent Document 2, the ethylene content in the skin layer can be adjusted within a predetermined range to control the winding slippage of the build-up film roll to a level that can be used as a product, but the prevention of the winding slippage of the build-up film roll is insufficient and there is room for improvement. Furthermore, in the laminated film described in Patent Document 2, low molecular weight components derived from ethylene in the skin layer gradually accumulate on the surface of the roll used in the production of the thermoplastic film. Thereafter, the accumulated ethylene components are retransferred to the film, causing foreign matter defects, so there is a problem that the ethylene content in the skin layer must be reduced as much as possible.

In addition, elastomer-containing films and sheets are known that use elastomers (rubber) to flexibly follow the shape changes of the other object (flexibility) in order to improve conformability to various surfaces (Patent Documents 3 to 5). However, the films described in Patent Documents 3 to 4 improve the adhesive strength with the other object they come into contact with, but are not a means to prevent slippage when rolling. In addition, the film described in Patent Document 5 improves vibration damping (the action of converting vibrations into thermal energy and attenuating them) by providing an elastomer layer and controlling the loss tangent of the elastomer layer, but is not a means to prevent slippage when rolling.

The main object of the present invention is to provide a novel laminate film that, when used as a protective film for an adhesive layer and a base film to form a roll, can suitably suppress the occurrence of shear between the protective film and the base film of the roll when a physical external force is applied to the roll, and can also reduce the accumulation of ethylene components on the surface of a transport roll such as a longitudinal stretching roll in a film manufacturing process. The laminate film can be suitably used as a protective film for the adhesive layer of a build-up film used in the manufacture of electronic components. The laminate film can also be used as a protective film in various fields, such as the manufacturing process of thermosetting resin members (adhesive layers) such as fiber-reinforced plastics. Another object of the present invention is to provide a novel roll that uses the laminate film and suppresses the occurrence of shear.

As a result of intensive research conducted by the present inventors to solve the above-mentioned problems, the inventors have found that in a laminated film having a core layer and a skin layer laminated on at least one side of the core layer, the skin layer is formed from a predetermined resin composition containing a propylene-based elastomer (a1), the ethylene and butene contents in the skin layer are set within a predetermined range, and the loss tangent tan δ of the skin layer of a cast raw sheet (unstretched) is controlled, so that when the skin layer is wound together with a base film as a protective film for a pressure-sensitive adhesive layer to form a roll, when a physical external force is applied to the roll, the occurrence of shear between the protective film and the base film of the roll is suitably suppressed, and further, the accumulation of ethylene components on the roll surface in the film manufacturing process can be reduced. The present invention was completed through further research based on this knowledge.

That is, the present invention includes the following.
Item 1. A core layer made of a composition (B) containing homopolypropylene (b1),
a skin layer formed on at least one side of the core layer and made of a composition (A) containing a propylene-based elastomer (a1), an ethylene-propylene block copolymer (a2), and an ethylene-propylene random copolymer (a3);
Equipped with
The composition (A) has a loss tangent tanδ of 0.06 or more at a vibration frequency of 1 Hz and a temperature of 20° C.,
The composition (A) has a total content of ethylene and butene of 8.0 mass% or more.
Item 2. The laminate film according to item 1, wherein the composition (A) has an ethylene content of 35.0 mass% or less.
Item 3. The laminate film according to item 1 or 2, wherein the composition (A) has a content of the propylene-based elastomer (a1) of 5 to 65 parts by mass, a content of the ethylene-propylene block copolymer (a2) of 30 to 90 parts by mass, and a content of the ethylene-propylene random copolymer (a3) of 5 to 65 parts by mass.
Item 4. The laminate film according to any one of items 1 to 3, which is used as a protective film for a pressure-sensitive adhesive layer of a build-up film.
Item 5. A roll formed by winding a build-up film including the laminate film according to any one of items 1 to 3.

According to the present invention, a novel laminate film can be provided that, when the laminate film is wound together with a base film as a protective film for the adhesive layer of a build-up film to form a roll, when a physical external force is applied to the roll, the occurrence of winding misalignment between the protective film of the roll and the base film of the roll can be suitably suppressed, and further, the accumulation of ethylene components on the longitudinal stretching roll in the film manufacturing process can be reduced. Such a laminate film can be suitably used, for example, as a protective film for the adhesive layer of a build-up film used in the manufacture of electronic components. Another object of the present invention is to provide a novel roll that uses the laminate film and in which the occurrence of winding misalignment is suppressed. The roll can be configured as a roll of a build-up film for electronic components.

The laminated film according to the present embodiment includes a core layer made of a composition (B) containing homopolypropylene (b1), and a skin layer laminated on at least one side of the core layer. The skin layer contains a propylene-based elastomer (a1), an ethylene-propylene block copolymer (a2), and an ethylene-propylene random copolymer (a3). The skin layer has a loss tangent tan δ of 0.06 or more at a vibration frequency of 1 Hz and a temperature of 20°C. The total content of ethylene and butene in the skin layer is 8.0 mass% or more. By having these characteristics, the laminated film according to the present embodiment can exhibit the effect of the present invention described above, that is, "when the laminated film according to the present embodiment is wound together with a base film as a protective film for the pressure-sensitive adhesive layer to form a roll, when a physical external force is applied to the roll, the occurrence of a winding slip between the protective film and the base film of the roll is suitably suppressed, and further, the accumulation of ethylene components on the roll surface in the film manufacturing process can be reduced."

The roll according to the present embodiment is a roll of a laminate using the laminate film according to the present embodiment as a protective film. For example, the roll can be a roll formed by winding a build-up film including the laminate film according to the present embodiment. The specific configuration of the roll according to the present embodiment is a laminate in which a base film, an adhesive layer, and the laminate film according to the present embodiment are laminated in this order, and the adhesive layer and either the skin layer or the core layer of the laminate film are in contact with each other, and the laminate can be wound around a core. The roll according to the present embodiment uses the laminate film according to the present embodiment as a protective film, so that when a physical external force is applied to the roll, the occurrence of a winding misalignment between the protective film and the base film of the roll is suitably suppressed.

The laminated film according to this embodiment and the roll using the laminated film are described in detail below. In this specification, the "to" in the numerical range means "greater than or equal to" and "less than or equal to." In other words, the expression "α to β" means "greater than or equal to α and less than or equal to β" or "greater than or equal to β and less than or equal to α," and includes α and β as ranges.

<1. Laminated film>
The laminated film according to this embodiment includes a core layer and a skin layer laminated on at least one side of the core layer.

The thickness of the laminate film according to this embodiment can be appropriately selected depending on the application of the laminate film. For example, from the viewpoint of suitably using the laminate film according to this embodiment as a protective film for a build-up film used in the manufacture of electronic components, the thickness is preferably 200 μm or less, more preferably 100 μm or less, even more preferably 80 μm or less, and particularly preferably 60 μm or less, and the lower limit of the thickness is, for example, 3 μm or more, preferably 5 μm or more, and more preferably 10 μm or more. The thickness of the laminate film can be measured using a micrometer (JIS B-7502) in accordance with JIS C-2151.

The laminate film according to this embodiment is preferably a stretched laminate film, and more preferably a biaxially stretched laminate film.

(Core layer)
The resin forming the core layer is not particularly limited as long as it can function as a support for the skin layer, but a polypropylene resin is preferred.

Examples of polypropylene resins suitable for forming the core layer include a propylene homopolymer, a copolymer of propylene and ethylene, and a copolymer of propylene, ethylene, and an α-olefin having 4 to 20 carbon atoms (for example, at least one of ethylene, butene, pentene, hexene, etc.). Among these, it is preferable to use one type of polypropylene homopolymer alone or a mixture of two or more types, since this makes it easier to increase the mechanical strength and heat resistance of the core layer and further allows the surface of the core layer to be appropriately roughened.

The content of polypropylene resin in the resin forming the core layer is not particularly limited, but from the viewpoint of functioning as a support for the skin layer, it is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 98% by mass or more.

The melt flow rate (MFR) of the polypropylene resin is preferably 0.5 g/10 min to 9.0 g/10 min, more preferably 1.0 g/10 min to 6.0 g/10 min, and even more preferably 2.0 g/10 min to 5.0 g/10 min. When the melt flow rate of the polypropylene resin is equal to or higher than the lower limit, sufficient resin fluidity is obtained, the thickness of the cast raw sheet is easily controlled, and a film that is stretched with high precision in the width direction is easily produced, which is preferable. In addition, when the melt flow rate of the polypropylene resin is equal to or lower than the upper limit, the mechanical properties of the resulting sheet are easily improved, and the stretchability is easily improved, which is preferable. In this specification, the MFR of the resin can be measured at 230°C and a load of 21.18 N using a melt flow indexer (for example, a melt indexer manufactured by Toyo Seiki Seisakusho Co., Ltd.) in accordance with JIS K-7210 (1999).

The weight-average molecular weight (Mw) of the polypropylene resin is preferably 200,000 to 600,000, and more preferably 250,000 to 500,000. When the weight-average molecular weight Mw of the polypropylene resin is equal to or greater than the lower limit, sufficient resin fluidity is obtained, the thickness of the cast raw sheet is easily controlled, and a film suitable for a core layer that is stretched with high precision in the width direction is easily produced, which is preferable. In addition, when the weight-average molecular weight Mw of the polypropylene resin is equal to or less than the upper limit, the mechanical properties of the resulting sheet are easily improved, and a film suitable for a core layer with improved stretchability is obtained, which is preferable.

The molecular weight distribution (Mw/Mn) of the polypropylene resin, calculated as the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably 4 or more, and more preferably 4.5 or more. If the molecular weight distribution (Mw/Mn) of the polypropylene resin is equal to or more than the above lower limit, it is preferable because β crystals can be sufficiently generated in the cast raw sheet before stretching, and it is easy to obtain an appropriate strength for the core layer. The upper limit of the molecular weight distribution (Mw/Mn) of the polypropylene resin is not particularly limited, but is preferably 10 or less.

The weight average molecular weight (Mw) and number average molecular weight (Mn) of polypropylene resin can be measured by gel permeation chromatography (GPC). There are no particular limitations on the GPC device used in the GPC method, and a commercially available high-temperature GPC measuring device capable of analyzing the molecular weight of polyolefins (for example, a high-temperature GPC measuring device with built-in differential refractometer (RI), HLC-8121GPC-HT, manufactured by Tosoh Corporation) can be used. In this case, for example, the measurement can be performed using the GPC column, column temperature, eluent, and flow rate described in the examples. Usually, a calibration curve is prepared using standard polystyrene, and the weight average molecular weight (Mw) and number average molecular weight (Mn) are obtained by polystyrene conversion.

The thickness of the core layer can be appropriately selected depending on the application of the laminate film according to this embodiment. For example, from the viewpoint of suitably using the laminate film according to this embodiment as a protective film for a build-up film used in the manufacture of electronic components, the thickness of the core layer can be 50% or more and 93% or less of the total thickness of the laminate film. The thickness of the core layer can be measured by cutting the laminate film and observing the cross section under a microscope.

(Skin layer)
The skin layer is laminated on at least one side of the core layer. In the laminate film according to the present embodiment, at least one surface may be constituted by the surface of the skin layer.

In the laminated film according to this embodiment, the core layer comes into contact with the surface of the object to be protected, thereby suitably protecting the object to be protected. For example, when the laminated film is used as a protective film for the adhesive layer, and the adhesive layer applied to the base film comes into contact with the core layer, and the laminated film is wound together with the base film to form a roll, when a physical external force is applied to the roll, the occurrence of misalignment between the protective film and the base film of the roll can be suitably suppressed.

The skin layer may be laminated on both sides of the core layer. In the laminate film according to this embodiment, both surfaces are constituted by the surface of the skin layer, so that the skin layer of the laminate film can suitably protect the object to be protected, and furthermore, it is possible to suitably suppress the occurrence of misalignment between the protective film and the base film of the roll. When skin layers are formed on both sides of the core layer, the resin composition forming each skin layer, the thickness of the skin layer, the surface characteristics of the skin layer, etc. may be the same or different.

In the laminated film according to this embodiment, a skin layer may be laminated on one side of the core layer, and a layer different from the skin layer may be laminated on the other side. It is preferable that the layer different from the skin layer is also formed from a polypropylene resin.

The skin layer includes a propylene-based elastomer (a1) and a propylene-based copolymer. Specifically, the skin layer can be formed from a resin composition (A) including a propylene-based elastomer (a1), an ethylene-propylene block copolymer (a2), and an ethylene-propylene random copolymer (a3).

In the skin layer, the mass ratio of the propylene-based elastomer (a1), the ethylene-propylene block copolymer (a2), and the ethylene-propylene random copolymer (a3) (propylene-based elastomer (a1):ethylene-propylene block copolymer (a2):ethylene-propylene random copolymer (a3)) is not particularly limited, but from the viewpoint of making the surface characteristics (dynamic friction coefficient, etc.) of the skin layer favorable, reducing the deposition of the ethylene component on the roll surface in the film production process, and favorably exerting the effects of the present invention, it is preferably about 5:90:5 to 40:40:20, more preferably about 5:90:5 to 30:40:30, even more preferably about 5:90:5 to 30:60:10, and particularly preferably about 5:90:5 to 20:70:10.

The contents of the propylene-based elastomer (a1), ethylene-propylene block copolymer (a2), and ethylene-propylene random copolymer (a3) in the skin layer are not particularly limited, but from the viewpoint of fully exerting the effects of the present invention, it is preferable that the propylene-based elastomer (a1) is in the range of 5 to 65 parts by mass, the ethylene-propylene block copolymer (a2) is in the range of 30 to 90 parts by mass, and the ethylene-propylene random copolymer (a3) is in the range of 5 to 65 parts by mass. Furthermore, from the viewpoint of effectively suppressing the staining of the ethylene component on the roll surface, it is more preferable that the propylene-based elastomer (a1) is in the range of 5 to 55 parts by mass, the ethylene-propylene block copolymer (a2) is in the range of 30 to 80 parts by mass, and the ethylene-propylene random copolymer (a3) is in the range of 15 to 65 parts by mass. Furthermore, from the viewpoint of effectively suppressing the occurrence of winding slippage, it is even more preferable that the propylene-based elastomer (a1) is in the range of 15 to 55 parts by mass, the ethylene-propylene block copolymer (a2) is in the range of 30 to 70 parts by mass, and the ethylene-propylene random copolymer (a3) is in the range of 15 to 55 parts by mass.

Similarly, the content of the propylene-based elastomer (a1), ethylene-propylene block copolymer (a2), and ethylene-propylene random copolymer (a3) in the skin layer is preferably in the range of 5 to 65% by mass for the propylene-based elastomer (a1), 30 to 90% by mass for the ethylene-propylene block copolymer (a2), and 5 to 65% by mass for the ethylene-propylene random copolymer (a3). From the viewpoint of effectively suppressing the ethylene component from staining the roll surface, it is more preferable that the content of the propylene-based elastomer (a1) is in the range of 5 to 55% by mass, the content of the ethylene-propylene block copolymer (a2) is in the range of 30 to 80% by mass, and the content of the ethylene-propylene random copolymer (a3) is in the range of 15 to 65% by mass. Furthermore, from the viewpoint of effectively suppressing the occurrence of winding slippage, it is even more preferable that the propylene-based elastomer (a1) is in the range of 15 to 55 mass%, a2 is in the range of 30 to 70 mass%, and the ethylene-propylene random copolymer (a3) is in the range of 15 to 55 mass%.

The propylene-based elastomer (a1) used in composition (A) is a propylene-ethylene-α-olefin terpolymer containing structural units derived from propylene, structural units derived from ethylene, and structural units derived from an α-olefin having 4 to 20 carbon atoms. Specific examples of α-olefins having 4 to 20 carbon atoms include 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1-hexadecene, 3-methyl-1-butene, and 4-methyl-1-pentene.

The propylene-based elastomer (a1) used in composition (A) may be, for example, a propylene-ethylene-1-butene copolymer. A copolymer having 50 to 87 mol % of propylene-derived structural units, 10 to 25 mol % of ethylene-derived structural units, and 3 to 25 mol % of 1-butene-derived structural units is preferred.

The propylene-based elastomer (a1) used in composition (A) is preferably a copolymer having an ethylene content of 1 to 15 mass%, more preferably a copolymer having an ethylene content of 3 to 12 mass%.

As the propylene-based elastomer (a1) used in composition (A), a copolymer having a 1-butene content of 1 to 15 mass % is preferred, and a copolymer having a 1-butene content of 1 to 12 mass % is more preferred.

From the viewpoint of moldability, the MFR of the propylene-based elastomer (a1) is preferably 3 to 14 g/10 min, and more preferably 5 to 12 g/10 min.

The ethylene-propylene block copolymer (a2) used in composition (A) is preferably a block copolymer having an ethylene content of 1 to 15 mass%, more preferably a block copolymer having an ethylene content of 3 to 12 mass%.

From the viewpoint of moldability, the MFR of the ethylene-propylene block copolymer (a2) is preferably 3 to 12 g/10 min, and more preferably 5 to 10 g/10 min.

The weight average molecular weight (Mw) of the ethylene-propylene block copolymer (a2) is not particularly limited, but is preferably 200,000 to 600,000, and more preferably 300,000 to 500,000. The molecular weight distribution (Mw/Mn), calculated as the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably 4 or more, and more preferably 5 or more. The method for measuring these weight average molecular weights (Mw) and number average molecular weights (Mn) is the same as the method for measuring the polypropylene resin described above.

The ethylene-propylene random copolymer (a3) used in composition (A) is preferably a random copolymer having an ethylene content of 0.5 to 6 mass%, more preferably a random copolymer having an ethylene content of 1 to 5 mass%.

From the viewpoint of moldability, the MFR of the ethylene-propylene random copolymer (a3) is preferably 5 to 14 g/10 min, and more preferably 7 to 12 g/10 min.

The weight average molecular weight (Mw) of the ethylene-propylene random copolymer (a3) is not particularly limited, but is preferably 200,000 to 600,000, and more preferably 300,000 to 500,000. The molecular weight distribution (Mw/Mn), calculated as the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably 4 or more, and more preferably 5 or more. The method for measuring these weight average molecular weights (Mw) and number average molecular weights (Mn) is the same as the method for measuring the polypropylene resin described above.

In the laminate film according to this embodiment, the propylene content in the skin layer is preferably 65% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 85% by mass or more.

In the laminated film according to this embodiment, the total content of ethylene and butene in the skin layer may be 8.0% by mass or more. From the viewpoint of making the surface characteristics (dynamic friction coefficient, etc.) of the skin layer suitable, reducing the deposition of the ethylene component on the roll surface in the film manufacturing process, and suitably exerting the effects of the present invention, the total content of ethylene and butene in the skin layer is preferably in the range of 8.0 to 35.0% by mass, more preferably in the range of 8.0 to 25.0% by mass. From the same viewpoint, the content of ethylene in the skin layer is preferably 35.0% by mass or less, more preferably 25.0% by mass or less, even more preferably 15.0% by mass or less, even more preferably 10.0% by mass or less, and particularly preferably 9.5% by mass or less. The lower limit of the ethylene content is, for example, 5.0% by mass or more, 7.0% by mass or more, etc. From the same viewpoint, the butene content in the skin layer is preferably 35.0% by mass or less, more preferably 25.0% by mass or less, even more preferably 5.0% by mass or less, and particularly preferably 3.0% by mass or less. The lower limit of the butene content is preferably, for example, 0.1% by mass or more, 0.3% by mass or more, 0.5% by mass or more, etc. The ethylene and butene contents in the skin layer are derived from the ethylene units and butene units contained in the propylene-based elastomer (a1), the ethylene-propylene block copolymer (a2), and the ethylene-propylene random copolymer (a3). The ethylene and butene contents in the skin layer are determined using a nuclear magnetic resonance apparatus or the like. More specifically, in the present invention, AVANCE NEO700 manufactured by Bruker is used, and the observation nucleus is ¹³ C (176.08 MHz).

The measurement mode is inverse gated decoupling (quantitative method), the shift standard is 5 propylene unit chains (mmmm) (21.95 ppm), the number of accumulations is 2048, and the temperature is 130°C.

The monomer composition was calculated from the integral value of the main chain methylene carbon based on the monomer chain, with reference to literature such as "G.J. Ray et al., Macromolecules 1977, 10, p.773-778" and "Y.-D. Zhang et al., Polym. J. 2003, 35, p.551-559." The total ethylene and butene content in the skin layer was calculated by measuring the ethylene content and butene content of each of the resins used to form the skin layer using the method described above, and taking into account the blending ratio of each resin in the skin layer.

The laminated film according to this embodiment is a strip-shaped sheet of a single-skin layer cast material made of composition (A), and the loss tangent tanδ measured using a dynamic viscoelasticity device at a vibration frequency of 1 Hz and a temperature of 20°C is 0.06 or more. Because the surface of the skin layer of the laminated film according to this embodiment has such surface characteristics, it is possible to preferably exert the effects of the present invention described above.

A single-skin layer cast raw sheet made of composition (A) is cut into a strip of 40 mm lengthwise and 8 mm widthwise, and the loss tangent tanδ at a vibration frequency of 1 Hz and a temperature of 20°C is measured by the following measurement method. For a more specific measurement method, the method described in the Examples is adopted.

[Loss tangent tan δ]
Dynamic viscoelasticity is measured using a dynamic viscoelasticity measuring device (for example, a "Viscoelasticity Measuring Device (Model: DMS6100)" manufactured by Seiko Instruments Inc.). A skin layer single-film cast original sheet made of composition (A) was cut into a rectangular shape, and the temperature dependence of the skin layer single-film cast original sheet made of composition (A) was measured in accordance with JIS-K7244 (1999 edition) under the measurement conditions of a tensile mode, a vibration frequency of 1 Hz, a chuck distance of 20 mm, and a heating rate of 5°C/min. From the measurement results, the loss tangent tan δ at 20°C was calculated from the temperature dispersion of the loss tangent.

The laminated film according to this embodiment has a dynamic friction coefficient of 1.0 or more at a pressure of 5.56 gf/ ^cm2 , measured by overlapping the surface of the skin layer and the biaxially oriented polyester film. Furthermore, the dynamic friction coefficient of 1.0 or more at a pressure of 33.33 gf/ ^cm2 , measured by overlapping the surface of the skin layer and the biaxially oriented polyester film. Since the surface of the skin layer of the laminated film according to this embodiment has such surface characteristics, it is possible to suitably exhibit the effects of the present invention described above.

For the surface of the skin layer, the kinetic friction force D1 at a pressure of 5.56 gf/ ^cm2 and the kinetic friction force D2 at a pressure of 33.33 gf/ ^cm2 are measured by the following friction force measurement method. Note that, as a more specific measurement method, the method described in the examples is adopted.

[Friction force]
Various frictional forces are measured using a surface property measuring device (for example, "HEIDON Tribogear (Model: TYPE14FW)" manufactured by Shinto Scientific Co., Ltd.). The laminated film is cut into a length of 20 cm in the vertical direction and 3 cm in the horizontal direction to prepare a test film. Next, the test film is set on a 30 mm flat indenter (contact area 9 ^cm2 ) without any wrinkles. At this time, the skin layer of the test film is set so that it is on the outside. Next, a biaxially oriented polyester film (arithmetic mean height (Sa) 0.001 μm, root mean square height (Sq) 0.001 μm, root mean square slope (Sdq) 0.001, interface area development ratio (Sdr) 0.000%, core level difference (Sk) 0.002 μm, protruding valley height (Svk) 0.001 μm, protruding valley spatial volume (Vvv) 0.000 ml/m2, core spatial volume (Vvc) 0.001 ml/ ^m2 , core volume (Vmc) 0.001 ml/ ^m2 , maximum height (Sz) 0.08 ^μm , thickness 50 μm) used for measuring the frictional force of the skin layer was cut into a length of 20 cm in the vertical direction and 8 cm in the horizontal direction, and set on a movable table in a wrinkle-free state so that the untreated side that has not been subjected to surface modification treatment such as corona discharge is facing up. The biaxially stretched polyester film has an arithmetic mean height Sa (ISO25178) of 0.001 μm, a maximum height Sz (ISO25178) of 0.08 μm, a thickness (JIS C-2318) of 50 μm, a static friction coefficient (JIS K-7125) of 0.46, a dynamic friction coefficient (JIS K-7125) of 0.40, a haze (JIS K-7105) of 0.9%, and a total light transmittance (JIS K-7105) of 92.0%, and is used to measure the static friction coefficient and the dynamic friction coefficient by being brought into contact with the skin layer.

In this state, the surface of the skin layer of the test film and the biaxially stretched polyester film are overlapped and the dynamic friction coefficient D1 at a pressure of 5.56 gf/ ^cm2 is measured at a table speed of 100 mm/min, a vertical load of 50 gf (equivalent pressure value of 5.56 gf/ ^cm2 ), a displacement of 60 mm or more (one-way movement), a data sampling rate of every 50 ms, a measurement temperature of 23°C, and a measurement humidity of 50% RH. The dynamic friction coefficient D1 (average value between displacements of 1 to 60 mm) is extracted from the values obtained in each of the three measurements.

The dynamic friction coefficient D2 at a pressure of 33.33 gf/ ^cm2 is measured by overlapping the surface of the skin layer of the test film and the biaxially stretched polyester film, with a table speed of 100 mm/min, a vertical load of 300 gf (equivalent pressure value of 33.33 gf/ ^cm2 ), a displacement of 60 mm or more (one-way movement), a data sampling rate of every 50 ms, a measurement temperature of 23°C, and a measurement humidity of 50% RH. The dynamic friction coefficient D2 (average value between displacements of 1 to 60 mm) is extracted from the values obtained in each of the three measurements.

The laminate film of this embodiment is preferably a surface-roughened laminate film in which the surface of the skin layer is roughened. Specifically, from the viewpoint of more suitably exerting the effects of the present invention described above, the surface roughness of the skin layer of the laminate film of this embodiment preferably satisfies at least one of the following (a) to (e), more preferably satisfies two or more, even more preferably satisfies three or more, and particularly preferably satisfies all of them.

(a) The root mean square height (Sq) is 0.48 to 1.12 μm.
(b) The interface area development ratio (Sdr) is 0.54 to 3.01%.
(c) The level difference (Sk) of the core portion is 1.03 to 2.78 μm.
(d) The protruding peak height (Spk) is 0.68 to 1.42 μm.
(e) The protruding valley height (Svk) is 0.17 to 0.64 μm.

The above physical properties related to the surface roughness of the skin layer are measured by the following surface roughness measurement method. For a more specific measurement method, use the method described in the Examples.

[Surface roughness]
An optical interference non-contact surface shape measuring instrument (for example, "VertScan 2.0 (model: R5500GML)" manufactured by Ryoka Systems Co., Ltd.) is used. As a measurement sample, a film is cut into an arbitrary size of about 20 cm square, and in a state where wrinkles are sufficiently stretched, it is set on the measurement stage using an electrostatic contact plate or the like. First, the measurement is performed using WAVE mode, a 530 white filter and a 1×BODY lens barrel are applied, and a 10x objective lens is used to perform measurement per field of view (470 μm×353 μm). This operation is performed for 10 points at 1 cm intervals in the flow direction from the center in both the flow direction and width direction of the surface of the skin layer of the target sample film. Next, the obtained data is subjected to noise removal processing using a median filter (3×3), and then Gaussian filter processing with a cutoff value of 176 μm is performed to remove waviness components. This makes it possible to appropriately measure the surface condition of the skin layer. Next, an analysis is performed using the "ISO parameters" in the "Bearing" plug-in function of the "VS-Viewer" analysis software of "VertScan 2.0", to determine Sq (μm), Sdr (%), Sk (μm), Spk (μm), and Svk (μm), and the average value of each value obtained at the above 10 locations is calculated.

The thickness of the skin layer can be appropriately selected depending on the application of the laminated film according to this embodiment. For example, from the viewpoint of suitably using the biaxially stretched surface film according to this embodiment as, for example, a protective film for a build-up film used in the manufacture of electronic components, the lower limit is preferably 0.05 μm or more, more preferably 0.1 μm or more, and even more preferably 1 μm or more, and the upper limit is preferably 80 μm or less, more preferably 50 μm or less, even more preferably 30 μm or less, and particularly preferably 10 μm or less. In addition, the thickness of the skin layer is preferably 0.5% or more, more preferably 1% or more, even more preferably 3% or more, even more preferably 5% or more, and especially preferably 10% or more, based on the entire thickness of the laminated film. In addition, the thickness of the skin layer is preferably 50% or less, more preferably 30% or less, even more preferably 25% or less, even more preferably 20% or less, and especially preferably 15% or less, based on the entire thickness of the biaxially stretched surface film. When a skin layer is formed on both sides of the laminate film according to this embodiment, the thickness of the skin layer on each side is preferably within the thickness range described above. Furthermore, when a skin layer is formed on both sides of the laminate film according to this embodiment, the thickness of each skin layer may be the same as or different from each other. The thickness of the skin layer can be measured by cutting the laminate film and observing the cross section under a microscope.

The skin layer and the core layer each preferably have an ash content of 100 ppm or less. Ash is caused by polymerization catalyst residues and the like, and can cause minute foreign bodies (fish eyes). If the ash content is 100 ppm or less, preferably 50 ppm or less, fish eyes can be prevented. The ash content can be adjusted by controlling the type and amount of catalyst used during polymerization of the resin that constitutes the skin layer and the core layer, respectively.

In this specification, the ash content of the skin layer and the core layer are measured in accordance with ISO 3451-1 as follows: The resin that forms the skin layer or the core layer is placed in a crucible and heated in a muffle furnace at 750°C for 1 hour, and the mass of the residue in the crucible is measured. The ratio of the mass of the residue in the crucible to the mass of the resin placed in the crucible is then calculated, and this is taken as the ash content.

The skin layer and the core layer may each contain an additive. The additive is not particularly limited, and known additives added to resin films can be used. The additive can be an additive generally used in polypropylene resins. Examples of additives include stabilizers such as antioxidants, chlorine absorbers, and ultraviolet absorbers, lubricants, plasticizers, flame retardants, antistatic agents, and colorants. Such additives may be added to the skin layer or the core layer to the extent that the effects of the present invention are not impaired. However, from the viewpoint of suitably using the biaxially stretched surface film according to this embodiment as a protective film for a build-up film used in the manufacture of electronic components, it is preferable not to add to the skin layer a component that may transfer to the protected member and affect the properties of the protected member, such as an antiblocking agent.

The laminated film according to this embodiment can be suitably used as a protective film for the adhesive layer of a build-up film used in the manufacture of electronic components. The laminated film can also be used as a protective film in various fields, such as the manufacturing process of thermosetting resin members such as fiber-reinforced plastics.

The laminated film according to the present embodiment can be obtained as a film in which the core layer and the skin layer are laminated, for example, by extrusion molding a resin composition that forms the core layer and the skin layer. For example, when manufacturing a laminated film as a biaxially stretched laminated film, it can be manufactured by extrusion molding a resin composition that forms the core layer and the skin layer, in a step (i) of manufacturing a cast raw sheet in which the core layer before stretching and the skin layer before stretching are laminated, and in a step (ii) of biaxially stretching the cast raw sheet. Specific examples of the steps (i) and (ii) are shown below.

In step (i), the resin compositions forming the core layer and the skin layer are first melt-kneaded at 200 to 260°C in an extruder, respectively, and then joined in a joining device and extruded from a T-die. At this time, it is preferable to use a polymer filter upstream of the joining device to remove coarse foreign matter from each resin.

The merging can be performed by known methods such as in a pipe before the T-die, by a lamination unit installed in the resin introduction section of the T-die (feed block method), or by laminating the resin after widening in the T-die (manifold lamination method). Of these, the manifold lamination method is superior in terms of lamination thickness accuracy, but an appropriate method can be selected from these, taking into account economics, etc.

Then, the laminate consisting of two or more layers thus extruded is pressed against at least one metal drum (cooling drum) whose drum surface is controlled at 20 to 100°C using an air knife, and formed into a sheet, to obtain a cast raw sheet having a thickness of, for example, 500 to 5,000 μm.

Next, in step (ii), the unstretched cast raw sheet is stretched to produce a biaxially stretched laminate film. The stretching is preferably biaxially stretched in the flow (longitudinal, also called MD) direction and the width (transverse, also called TD) direction, but may be biaxially stretched in an oblique direction if necessary.

Stretching methods include the tubular method, the tenter method, and a method of stretching between rolls with a difference in peripheral speed. Biaxial stretching can be performed simultaneously or sequentially. Since it is easy to obtain a biaxially stretched laminate film with no thickness unevenness and good flatness, simultaneous biaxial stretching using a tenter method, sequential biaxial stretching using a tenter method, and sequential biaxial stretching in which stretching is performed in the machine direction between rolls with a difference in peripheral speed and then stretching in the width direction using a tenter method are preferred.

In the sequential biaxial stretching method, for example, the cast raw sheet is first kept at a temperature of 100 to 160°C, passed between rolls with a speed difference, or guided to a tenter, and stretched 3 to 8 times in the machine direction, and then relaxed by about 0 to 10% as necessary. Next, the uniaxially stretched film is guided to a tenter and stretched 6 to 12 times in the width direction at a temperature of 120 to 185°C, and then relaxed by about 0 to 10% as necessary, heat-set, and wound up.

In the simultaneous biaxial stretching method, the cast raw sheet is introduced into a tenter and stretched to the above-mentioned stretch ratio in the machine direction and width direction at a temperature of 120 to 185°C, and then relaxed by about 0 to 10% as necessary and heat-set. The ends of the obtained biaxially stretched laminate film are then trimmed as necessary and wound up.

<2. Laminate>
The laminate according to the present embodiment is a laminate using the laminate film according to the present embodiment. The laminate according to the present embodiment has a configuration in which a base film, a pressure-sensitive adhesive layer, and the laminate film according to the present embodiment described above are laminated in this order.

The laminated film according to this embodiment is as described above.

In the laminate according to this embodiment, the laminate film according to this embodiment protects the adhesive layer formed on the base film. The materials and thicknesses of the base film and the thermosetting resin are appropriately selected according to the application of the laminate according to this embodiment. For example, a build-up film used in the manufacture of electronic components has a laminate structure in which an adhesive layer (an uncured or semi-cured thermosetting resin such as an epoxy resin that serves as a sealant for electronic boards) and a protective film are laminated on a base film such as a polyethylene terephthalate film. When the roll according to this embodiment is a roll of a build-up film, it is preferable that the base film is a polyethylene terephthalate film and the adhesive layer is formed of an uncured or semi-cured epoxy resin.

The thickness of the base film is not particularly limited, but is, for example, about 10 to 150 μm. The thickness of the adhesive layer is also not particularly limited, but is, for example, greater than or equal to the conductor thickness of the inner layer circuit board to be laminated, and is about the conductor thickness + (10 to 120) μm.

When the laminated film according to this embodiment is also used as a protective film in various fields such as the manufacturing process of thermosetting resin components such as fiber-reinforced plastics, it is preferable that the base film is a polyethylene terephthalate film and the adhesive layer is an uncured or semi-cured epoxy resin.

There are no particular limitations on the thickness of the laminate, but it is, for example, about 50 to 450 μm.

<3. Rolled body>
The roll according to the present embodiment is a roll of a laminate using the laminate film according to the present embodiment. For example, the roll can be a roll formed by winding a build-up film including the laminate film according to the present embodiment. The laminate constituting the roll is as described in the above section <2. Laminate>, and has a configuration in which a base film, a pressure-sensitive adhesive layer, and the laminate film according to the present embodiment described above are laminated in this order, and the pressure-sensitive adhesive layer is in contact with one side of either the skin layer or the core layer of the laminate film. The laminate is in a form wound around a core.

The laminated film according to this embodiment is as described above.

In the roll according to this embodiment, the laminate film according to this embodiment protects the adhesive layer formed on the base film. The materials and thicknesses of the base film and the thermosetting resin are appropriately selected according to the use of the roll according to this embodiment (specifically, the use of the above-mentioned laminate in the form of the roll). For example, a build-up film used in the manufacture of electronic components has a laminate structure in which an adhesive layer (an uncured or semi-cured thermosetting resin such as an epoxy resin that serves as a sealant for electronic boards) and a protective film are laminated on a base film such as a polyethylene terephthalate film. When the roll according to this embodiment is used as a roll of a build-up film, it is preferable that the base film is a polyethylene terephthalate film and the adhesive layer is formed of an uncured or semi-cured epoxy resin.

The thicknesses of the base film and the adhesive layer are as described above in the section <2. Laminate>.

As described above, when the laminate film according to this embodiment is also used as a protective film in various fields such as the manufacturing process of thermosetting resin members such as fiber-reinforced plastics, it is preferable that the base film is a polyethylene terephthalate film and the adhesive layer is an uncured or semi-cured epoxy resin.

The thickness of the laminate that constitutes the roll is as described above in the section <2. Laminate>.

The winding core is cylindrical or columnar, and the laminate is wound around the core in the circumferential direction.

The material of the core is not particularly limited, and examples include plastics that are less prone to deformation, fiber-reinforced plastics, paper, metals (iron, SUS, aluminum, etc.), etc. Among these, fiber-reinforced plastics are preferred because they are lightweight and have high strength. Examples of fiber-reinforced plastic cores include those made by forming carbon fiber, glass fiber, etc. into a cylindrical shape and impregnating and curing a curable resin such as unsaturated polyester resin.

The size of the winding core can be set according to the size of the desired winding body. The outer diameter of the circular cross section of the winding core is, for example, about 50 to 200 mm, and more preferably about 80 to 100 mm.

The present invention will be described in detail below with reference to examples and comparative examples. However, the present invention is not limited to the examples. Unless otherwise specified, parts and percentages refer to "parts by mass" and "% by mass", respectively.

[Example 1]
(Core layer)
Only pellets of homopolypropylene (b1) (MFR at 230° C. = 3.5 g/10 min, weight average molecular weight (MW) 290,000, number average molecular weight (Mn) 64,000, molecular weight distribution (Mw/Mn) 4.5) were fed from a hopper into extruder I and melted to prepare a resin composition for forming a core layer.

(Skin layer)
A propylene-based elastomer (a1) (MFR at 230° C. = 6.0 g/10 min, ethylene content of 0.49 mass% (calculated from a measured ethylene content of 14.2 mol%), butene content of 0.34 mass% (calculated from a measured butene content of 4.9 mol%)), an ethylene-propylene block copolymer (a2) (MFR at 230° C. = 8.0 g/10 min, ethylene content of 10.27 mass% (calculated from a measured ethylene content of 16.2 mol%)), and an ethylene-propylene random copolymer (a3) (MFR at 230° C. = 10 g/10 min, ethylene content of 0.20 mass% (calculated from a measured ethylene content of 6.0 mol%)) were dry-blended in the compounding ratios shown in Table 1, melt-kneaded at 230° C. using a kneading extruder, and pelletized. Next, the pellets were charged into an extruder II from a hopper and melted to prepare a resin composition for forming a skin layer.

[Preparation of Laminated Film]
The resin compositions (A) and (B) forming the skin layer and the core layer were extruded from a multi-manifold die at 230°C through a polymer filter to form a laminated film having a two-type three-layer structure of skin layer/core layer/skin layer, and the laminated film was cooled and solidified while being pressed by air pressure using an air knife onto a cooling drum whose surface temperature was adjusted to 45°C, to obtain a cast raw sheet having a thickness of 920 μm. Next, the cast raw sheet was heated to 130°C while in contact with a metal roll, and then stretched about 4.6 times in the flow direction between rolls with a difference in peripheral speed. Next, the uniaxially stretched film was introduced into a hot air oven while being clamped with a clip, preheated to 180°C, stretched about 10 times in the width direction, and then heat-set at 170°C while relaxing by about 10% in the width direction, to continuously obtain a laminated film having a thickness of about 20 μm. The thickness of the skin layer was 2.5 μm, and the thickness of the core layer was 15 μm. The edges of the obtained laminated film were trimmed, and then the film was wound around a core to obtain a roll of the laminated film.

[Examples 2 to 8]
In the preparation of the resin composition (A) forming the skin layer of Example 1, the compounding ratio shown in Table 1 was used, and the same procedure as in Example 1 was repeated to obtain roll-shaped laminate films.

[Comparative Example 1]
A roll-shaped laminate film was obtained in the same manner as in Example 1, except that in the preparation of the resin composition forming the skin layer in Example 1, the propylene-based elastomer (a1) used in the skin layer was replaced with low-density polyethylene to give the compounding ratio shown in Table 1.

[Comparative Example 2]
In the preparation of the resin composition forming the skin layer of Example 1, the propylene-based elastomer (a1) and the ethylene-propylene random copolymer (a3) used in the skin layer were not used, and the entire resin composition was replaced with the ethylene-propylene block copolymer (a2) in the blending ratio shown in Table 1. A roll-shaped laminate film was obtained in the same manner as in Example 1, except that the propylene-based elastomer (a1) and the ethylene-propylene random copolymer (a3) used in the skin layer were not used, and the entire resin composition was replaced with the ethylene-propylene block copolymer (a2).

[Comparative Example 3]
In the preparation of the resin composition forming the skin layer of Example 1, the propylene-based elastomer (a1) used in the skin layer was not used, and was replaced with an ethylene-propylene block copolymer (a2) and an ethylene-propylene random copolymer (a3) in the blending ratio shown in Table 1. A roll-shaped laminate film was obtained in the same manner as in Example 1.

[Comparative Example 4]
In the preparation of the resin composition forming the skin layer of Example 1, the propylene-based elastomer (a1), the ethylene-propylene block copolymer (a2), and the ethylene-propylene random copolymer (a3) used in the skin layer were not used, and the entire resin composition was replaced with homopolypropylene (b1) (MFR at 230°C = 3.5 g/10 min) in the blending ratio shown in Table 1. A roll-shaped laminate film was obtained in the same manner as in Example 1, except that the blending ratio was as shown in Table 1.

[Preparation of Single-Skin Layer Cast Raw Sheet]
The resin composition (A) forming each skin layer in each of the Examples and Comparative Examples was extruded from a multi-manifold die at 230° C. through a polymer filter to form a single-film cast raw sheet consisting of only the skin layer, and the sheet was cooled and solidified while being pressed by air pressure using an air knife onto a cooling drum whose surface temperature was adjusted to 45° C., to obtain a cast raw sheet having a thickness of 150 μm. The cast raw sheet was used for measuring the loss tangent tanδ described later.

[Measurement of molecular weight and molecular weight distribution]
The weight average molecular weight, number average molecular weight, and molecular weight distribution of the homopolypropylene were measured by size exclusion chromatography (SEC), and the details of the measurement conditions are as follows.
Apparatus: HLC-8321GPC/HT (detector: differential refractometer (RI)) (manufactured by Tosoh Corporation)
Column: TSKgel guard column HHR (30) HT (7.5 mm I.D. x 7.5 cm) x 1 + TSKgel GMHHR-H (20) HT (7.8 mm I.D. x 30 cm) x 3 (manufactured by Tosoh Corporation)
Eluent: 1,2,4-trichlorobenzene (Fujifilm Wako Pure Chemical Industries, Ltd., for GPC) + BHT (0.05%)
Flow rate: 1.0 mL/min Detection conditions: polarity-(-)
Injection volume: 0.3 mL
Column temperature: 140 ° C.
System temperature: 40°C
Sample concentration: 1 mg/mL
Sample pretreatment: The sample was weighed, and a solvent (1,2,4-trichlorobenzene with 0.1% BHT added) was added and the sample was dissolved by shaking at 140° C. for 1 hour. Then, the sample was heated and filtered through a 0.5 μm sintered filter.
Calibration curve: A calibration curve of a quintic approximation curve was prepared using standard polystyrene manufactured by Tosoh Corporation. However, the molecular weight was converted to the molecular weight of polypropylene using the Q-factor. From the obtained calibration curve and SEC chromatogram, the number average molecular weight (Mn), weight average molecular weight (Mw), and Z average molecular weight (Mz) were obtained using analysis software for the measurement device. The values of Mw and Mn were used to obtain the molecular weight distribution (Mw/Mn). In addition, the values of Mz and Mn were used to obtain the molecular weight distribution (Mz/Mn).

[Loss tangent tan δ]
The dynamic viscoelasticity measuring device used was a "Viscoelasticity measuring device (model: DMS6100)" manufactured by Seiko Instruments Inc. As a measurement sample, a skin layer single-film cast raw sheet made of composition (A) was cut into a strip of 40 mm in the vertical direction and 8 mm in the horizontal direction, and the temperature dependency of the cast raw sheet was measured under the measurement conditions shown below in accordance with JIS-K7244 (1999 edition).
Test mode: tension mode Chuck distance: 20 mm
Vibration frequency: 1Hz
Strain amplitude: 10 μm
Tension Gain: 1.2
Initial force amplitude: 100 mN
Temperature range: -60 to 150°C
Heating rate: 5° C./min
Measurement atmosphere: in nitrogen Measurement thickness: the sheet thickness in the above [Preparation of single-skin layer cast raw sheet] was used. From the measurement results, the loss tangent tan δ at a temperature dispersion of the loss tangent at 20° C. was calculated. The results are shown in Table 1.

[Surface roughness]
A "VertScan 2.0 (model: R5500GML)" manufactured by Ryoka Systems Co., Ltd. was used as an optical interference type non-contact surface shape measuring instrument. As a measurement sample, each laminated film of the examples and comparative examples was cut into an arbitrary size of about 20 cm square, and in a state where wrinkles were sufficiently stretched so that they were no longer wrinkled, it was set on a measurement stage using an electrostatic contact plate or the like. First, the measurement was performed using WAVE mode, a 530 white filter and a 1×BODY lens barrel were applied, and a measurement was performed per field of view (470 μm × 353 μm) using a 10x objective lens. This operation was performed at 10 points at 1 cm intervals in the flow direction from the center of the surface of the skin layer of the target sample film in both the flow direction and width direction. Next, the obtained data was subjected to noise removal processing using a median filter (3×3), and then Gaussian filter processing with a cutoff value of 176 μm was performed to remove the waviness component. This made it possible to properly measure the surface condition of the skin layer. Next, analysis was performed using "ISO parameters" in the plug-in function "bearing" of the analysis software "VS-Viewer" of "VertScan 2.0" to determine Sq (μm), Sdr (%), Sk (μm), Spk (μm), and Svk (μm), and the average values obtained at the above 10 locations were calculated. The results are shown in Table 1.

[Friction force]
A "HEIDON Tribogear (Type: TYPE14FW)" manufactured by Shinto Scientific Co., Ltd. was used as a surface property measuring device. Each laminate film of the Examples and Comparative Examples was cut into a length of 20 cm and a width of 3 cm to prepare a test film. Next, the test film was set on a 30 mm flat indenter (contact area ⁹ cm2) without any wrinkles. At this time, the skin layer of the test film was set on the outside. Next, a biaxially oriented polyester film (arithmetic mean height (Sa) 0.001 μm, root mean square height (Sq) 0.001 μm, root mean square slope (Sdq) 0.001, interface area development ratio (Sdr) 0.000%, core level difference (Sk) 0.002 μm, protruding valley height (Svk) 0.001 μm, protruding valley spatial volume (Vvv) 0.000 ml/m2, core spatial volume (Vvc) 0.001 ml/ ^m2 , core volume (Vmc) 0.001 ml/ ^m2 , maximum height (Sz) 0.08 ^μm , thickness 50 μm) used for measuring the frictional force of the skin layer was cut into a length of 20 cm in the vertical direction and 8 cm in the horizontal direction, and set on a movable table in a wrinkle-free state so that the untreated side that had not been subjected to surface modification treatment such as corona discharge was facing up.

In this state, the surface of the skin layer of the test film and the biaxially stretched polyester film were overlapped to measure the dynamic friction coefficient D1 at a pressure of 5.56 gf/ ^cm2 , with a table speed of 100 mm/min, a vertical load of 50 gf (equivalent pressure value of 5.56 gf/ ^cm2 ), a displacement of 60 mm or more (one-way movement), a data sampling rate of every 50 ms, a measurement temperature of 23°C, and a measurement humidity of 50% RH. The dynamic friction coefficient D1 (average value between displacements of 1 to 60 mm) was extracted from the values obtained from each of the three measurements. The results are shown in Table 1.

The surface of the skin layer of the test film was overlapped with the biaxially stretched polyester film to measure the kinetic friction force D2 at a pressure of 33.33 gf/ ^cm2 , with a table speed of 100 mm/min, a vertical load of 300 gf (equivalent pressure value of 33.33 gf/ ^cm2 ), a displacement of 60 mm or more (one-way movement), a data sampling rate of every 50 ms, a measurement temperature of 23°C, and a measurement humidity of 50% RH. The kinetic friction force D2 (average value between displacements of 1 to 60 mm) was extracted from the values obtained from each of the three measurements. The results are shown in Table 1.

[Evaluation of winding misalignment of rolled body]
A base film having an adhesive layer (580 mm wide x 300 m, non-silicone PET separator film, adhesive layer: epoxy adhesive (thermosetting resin)) was prepared. The base film and each laminate film prepared in the examples and comparative examples (slit to 580 mm wide) were laminated together so that the skin layer of the laminate film and the adhesive layer of the base film were in contact with each other to prepare a laminate, which was used as an evaluation sample. The evaluation sample was wound around a core (length 620 mm, diameter 92.5 mm) at a speed of 50 m/min to form a roll. Next, the roll was packed in a cardboard box, and after a vibration test (level 3) according to the method specified in JIS-Z0232, the unevenness of the film roll end surface was evaluated in four stages: "excellent: A+", "good: A", "average: B" and "poor: C", and the case of "average: B" or higher was evaluated according to the following criteria. The results are shown in Table 1.
A+: The unevenness difference of the film roll end surface is 0 mm or more and 1.0 mm or less. A: The unevenness difference of the film roll end surface is more than 1.0 mm and 3.0 mm or less. B: The unevenness difference of the film roll end surface is more than 3.0 mm and 5.0 mm or less. C: The unevenness difference of the film roll end surface is more than 5.0 mm.

[Roller soiling evaluation]
The stains of the ethylene component on the roll surface were evaluated by cleaning the longitudinal stretching rolls before the start of film formation, and visually observing the state of stains one hour after the start of film formation, and evaluating the state difference of the longitudinal stretching roll surface in four stages: "excellent: A+", "good: A", "fair: B", and "poor: C". The results were evaluated according to the following criteria, with "fair: B" or higher being considered as passing. The results are shown in Table 1.
A+: No change from before film formation A: Almost no stains B: Very slight stains can be seen C: Cloudy white stains can be clearly seen

Claims (5)

A core layer made of a composition (B) containing homopolypropylene (b1);
a skin layer formed on at least one side of the core layer and made of a composition (A) containing a propylene-based elastomer (a1), an ethylene-propylene block copolymer (a2), and an ethylene-propylene random copolymer (a3);
Equipped with
The propylene-based elastomer (a1) of the skin layer is a propylene-ethylene-1-butene copolymer,
in the skin layer, a mass ratio of the propylene-based elastomer (a1), the ethylene-propylene block copolymer (a2), and the ethylene-propylene random copolymer (a3) (propylene-based elastomer (a1):ethylene-propylene block copolymer (a2):ethylene-propylene random copolymer (a3)) is 5:90:5 to 40:40:20,
The composition (A) has a loss tangent tanδ of 0.06 or more at a vibration frequency of 1 Hz and a temperature of 20° C.,
The composition (A) has a total content of ethylene and butene of 8.0 mass% or more. The laminated film according to claim 1, wherein the composition (A) has an ethylene content of 35.0% by mass or less. The laminated film according to claim 1 or 2, wherein the composition (A) contains 5 to 65 parts by mass of the propylene-based elastomer (a1), 30 to 90 parts by mass of the ethylene-propylene block copolymer (a2), and 5 to 65 parts by mass of the ethylene-propylene random copolymer (a3). The laminate film according to any one of claims 1 to 3, which is used as a protective film for the adhesive layer of a build-up film. A roll comprising a build-up film including the laminate film according to any one of claims 1 to 3 wound up.