Laminated film

Abstract

To provide a novel laminate film in which, in the case where a protective film of an adhesive layer of build-up film is wound together with a base film to form a winding body, generation of winding slippage between the protective film and the base film of the winding body is preferably suppressed when physical external force is added to the winding body, and furthermore, accumulation of an ethylene component on a longitudinal stretching roll in a film production step can be reduced.SOLUTION: A laminate film comprises: a core layer made of composition (B) containing homopolypropylene (b1); and a skin layer which is formed on at least one surface side of the core layer, and made of composition (A) containing propylene-based elastomer (a1), ethylene / propylene block copolymer (a2), and ethylene / propylene random copolymer (a3), where the composition (A) has loss tangent tanδ of 0.06 or more at vibration frequency 1 Hz and temperature 20°C, and the composition (A) has the total content ratio of ethylene and butene of 8.0 mass% or more.

Description

[Technical Field]

[0001] The present invention relates to a laminated film. Specifically, it relates to a laminated film comprising a core layer and a skin layer, which can be used, for example, as a protective film for build-up films used in the manufacture of electronic components. [Background technology]

[0002] Polypropylene film is widely used as an industrial material film, including for packaging, due to its excellent lightweight properties, thermal stability, and mechanical stability. In recent years, in particular, the low surface energy of polypropylene film has led to its widespread use as a protective material and release agent in the manufacturing processes of electronic components and circuit boards, thermosetting resin components such as fiber-reinforced plastics, and photosensitive films. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 6354634 [Patent Document 2] Japanese Patent Publication No. 2018-204002 [Patent Document 3] Patent No. 6341049 [Patent Document 4] Japanese Patent Publication No. 2017-66395 [Patent Document 5] WO2018 / 079161 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Polypropylene film is used, for example, as a protective film to protect the adhesive layer in build-up films used in the manufacture of electronic components. It is wound, stored, distributed, and used as build-up film rolls. A build-up film has a laminated structure in which a base film (such as PET film), an adhesive layer (an uncured or semi-cured thermosetting resin that serves as a encapsulant for electronic circuit boards), and a protective film are laminated together. In such build-up films, during the winding process after the protective film is laminated onto the adhesive layer applied to the base film, the adhesive layer (uncured or semi-cured thermosetting resin) is soft, so if the winding tension is increased, the adhesive layer is likely to overflow from the end face of the winding body. For this reason, in the winding process, the film is wound with low winding tension to prevent the thermosetting resin from overflowing. However, this leads to a problem in the transportation process of the build-up film winding body, where vibrations from the conveyor can easily cause misalignment between the protective film (polypropylene film) and the base film contained in the winding body.

[0005] Furthermore, to improve the processability of polypropylene films, it is common practice to add antiblocking agents to adjust the frictional force. However, polypropylene films used in build-up films have restrictions on the addition of antiblocking agents and other similar substances because they may affect the insulation performance of the thermosetting resin (insulating material that seals electronic circuit boards) they come into contact with. Specifically, if the surface of the polypropylene film is made uneven by the addition of antiblocking agents, when the polypropylene film (protective film) is peeled from the thermosetting resin, the antiblocking agent present on the surface of the polypropylene film may detach and transfer to the thermosetting resin. In the areas where the antiblocking agent has transferred to the surface of the thermosetting resin, the layer thickness of the thermosetting resin becomes thinner compared to other areas, which may lead to a decrease in insulation performance. For this reason, there are restrictions on the addition of fine particles such as antiblocking agents to polypropylene films used in build-up films.

[0006] As a polypropylene film that does not contain antiblocking agents and is given appropriate windability, for example, a film containing polypropylene and polyolefins other than polypropylene, and having an appropriate roughness on the film surface due to the compatibility of the resins, is known (Patent Document 1). Such a polypropylene film is considered suitable for processability as work in progress. However, when the film described in Patent Document 1 is used as a protective film for a build-up film, the roughness of the film surface makes it less likely for winding misalignment to occur due to a decrease in the contact area with the mating base film (PET film, etc.) caused by air entrainment during winding. On the other hand, roughening the film surface reduces the true contact area with the mating base film (PET film, etc.), which has a high smoothness. Therefore, 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 vibrations during the transport of the winded body wound as a build-up film.

[0007] Furthermore, as a means of preventing winding misalignment of build-up film windings, for example, a laminated film is known that comprises a core layer and a skin layer laminated on at least one side of the core layer, and by adjusting the ethylene content in the skin layer to a predetermined range, winding misalignment with the mating base film (PET film, etc.) is suppressed (Patent Document 2). However, while the laminated film described in Patent Document 2 can control the winding misalignment of the build-up film winding to a level usable as a product by adjusting the ethylene content in the skin layer to a predetermined range, it is insufficient in preventing winding misalignment of the build-up film winding, and there is room for improvement. Moreover, in the laminated film described in Patent Document 2, low molecular weight components derived from ethylene in the skin layer gradually accumulate on the roll surface used in the manufacture of thermoplastic films. Subsequently, the accumulated ethylene components are re-transferred 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.

[0008] Furthermore, to improve conformability to various surfaces, elastomer-containing films and sheets are known that utilize the property of flexible conforming to changes in the shape of the mating surface (flexibility) by using elastomers (rubber) (Patent Documents 3-5). However, the films described in Patent Documents 3-4 are intended to improve the adhesive strength with the mating substrate they come into contact with, and are not a means of preventing winding misalignment. Also, the film described in Patent Document 5 improves vibration damping (the effect of converting vibration into thermal energy and damping it) by providing an elastomer layer and controlling the loss tangent of the elastomer layer, and is not a means of preventing winding misalignment.

[0009] The present invention aims to provide a novel laminated film that, when wound together with a base film to form a winding body as a protective film for the adhesive layer, effectively suppresses winding misalignment between the protective film and the base film when physical external force is applied to the winding body, and further reduces the accumulation of ethylene components on the surface of conveying rolls such as longitudinal stretching rolls in the film manufacturing process. This laminated film can be suitably used as a protective film for the adhesive layer of build-up films used in the manufacture of electronic components. Furthermore, this laminated film can also be used as a protective film in various fields, such as in the manufacturing process of thermosetting resin members (adhesive layers) such as fiber-reinforced plastics. The present invention also aims to provide a novel winding body that suppresses winding misalignment using this laminated film.

[0010] The present inventors conducted diligent studies to solve the aforementioned problems and found that, in a laminated film comprising 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 content in the skin layer is set within a predetermined range, and furthermore, the loss tangent tanδ of the skin layer of the cast raw material sheet (unstretched) is controlled, so that when the protective film for the adhesive layer is wound together with the base film to form a winding body, winding misalignment between the protective film and the base film of the winding body is suitably suppressed when a physical external force is applied to the winding body, and furthermore, the deposition of ethylene components on the roll surface during the film manufacturing process can be reduced. The present invention was completed by further studies based on these findings.

[0011] In other words, the present invention includes the following: Item 1. A core layer comprising a composition (B) containing homopolypropylene (b1), Formed on at least one side of the core layer, and comprising a propylene-based elastomer (a1), A skin layer comprising composition (A) containing ethylene-propylene block copolymer (a2) and ethylene-propylene random copolymer (a3), Equipped with, The composition (A) has a loss tangent tanδ of 0.06 or more at an vibration frequency of 1 Hz and a temperature of 20°C. The composition (A) is a laminated film having a total content of ethylene and butene of 8.0% by mass or more. Item 2. The laminated film according to Item 1, wherein the composition (A) has an ethylene content of 35.0% by mass or less. Item 3. The composition (A) contains 5 to 65 parts by mass of the propylene elastomer (a1) and 30 to 65 parts by mass of the ethylene-propylene block copolymer (a2). The laminated film according to claim 1 or 2, wherein the content of the ethylene-propylene random copolymer (a3) ​​is 5 to 65 parts by mass, and the content of the ethylene-propylene random copolymer (a3) ​​is 90 parts by mass. Item 4. The laminated film according to any one of Items 1 to 3, which is used as a protective film for the adhesive layer of the build-up film. Item 5. A wound body formed by winding a build-up film including the laminated film according to any one of Items 1 to 3.

Advantages of the Invention

[0012] <C According to the present invention, when used as a protective film for the adhesive layer of a build-up film and wound together with a base film to form a wound body, when a physical external force is applied to the wound body, slippage between the protective film and the base film of the wound body is preferably suppressed, and further, deposition of an ethylene component on a longitudinal stretching roll in a film manufacturing process can be reduced, and a novel laminated film can be provided. Such a laminated film can be preferably used, for example, as a protective film for an adhesive layer of a build-up film used in the manufacture of electronic components. The present invention also aims to provide a novel wound body in which the occurrence of slippage is suppressed by using the laminated film. The wound body can be configured as a wound body of a build-up film for electronic components.

Modes for Carrying Out the Invention

[0013] The laminated film according to this embodiment includes a core layer made of a composition (B) containing homopolypropylene (b1), and a skin layer laminated on at least one surface 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 loss tangent tanδ of the skin layer at a vibration frequency of 1 Hz and a temperature of 20 °C is 0.06 or more. The total content of ethylene and butene in the skin layer is 8.0% by mass or more. By having these characteristics, the laminated film according to this embodiment can exhibit the above-described effect of the present invention, that is, "when used as a protective film for an adhesive layer and wound together with a base film to form a wound body, when a physical external force is applied to the wound body, winding deviation between the protective film of the wound body and the base film is preferably suppressed, and further, deposition of an ethylene component on the roll surface in the film manufacturing process can be reduced."

[0014] Further, the wound body according to this embodiment is a wound body of a laminate using the laminated film according to this embodiment as a protective film. For example, it can be a wound body around which a build-up film containing the laminated film of this embodiment is wound. As a specific configuration of the wound body according to this embodiment, it is a laminate in which a base film, an adhesive layer, and the laminated film according to this embodiment are laminated in this order, and either the adhesive layer and the skin layer or the core layer of the laminated film are in contact, and the laminate is wound around a winding core. By using the laminated film according to this embodiment as a protective film, the wound body according to this embodiment preferably suppresses the occurrence of winding deviation between the protective film of the wound body and the base film when a physical external force is applied to the wound body.

[0015] Hereinafter, the laminated film according to this embodiment and the wound body using the laminated film will be described in detail. In this specification, "~" in a numerical range means "above and below". That is, the notation α~β means α or more and β or less, or β or more and α or less, and includes α and β as a range.

[0016] <1. Laminated film> The laminated film according to this embodiment comprises a core layer and a skin layer laminated on at least one side of the core layer.

[0017] The thickness of the laminated film according to this embodiment can be appropriately selected depending on the application of the laminated film. For example, from the viewpoint of suitably using the laminated film according to this embodiment as a protective film for build-up films 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. 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 laminated film can be measured using a micrometer (JIS B-7502) in accordance with JIS C-2151.

[0018] The laminated film according to this embodiment is preferably a stretched laminated film, and more preferably a biaxially oriented laminated film.

[0019] (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 polypropylene resin is preferred.

[0020] Suitable polypropylene resins for forming the core layer include propylene homopolymers, copolymers of propylene and ethylene, and copolymers of propylene, ethylene, and α-olefins having 4 to 20 carbon atoms (for example, at least one of ethylene, butene, pentene, hexene, etc.). Among these, the use of one polypropylene homopolymer alone or a mixture of two or more is preferable because it is easy to increase the mechanical strength and heat resistance of the core layer, and the core layer surface can be appropriately roughened.

[0021] 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.

[0022] 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. A melt flow rate of polypropylene resin above the lower limit is preferable because it provides sufficient resin fluidity, makes it easier to control the thickness of the cast raw material sheet, and facilitates the production of a film stretched accurately in the width direction. Furthermore, a melt flow rate of polypropylene resin below the upper limit is preferable because it makes it easier to improve the mechanical properties and stretchability of the resulting sheet. In this specification, the MFR of the resin can be measured in accordance with JIS K-7210 (1999) using a melt flow indexer (for example, a melt indexer manufactured by Toyo Seiki Seisakusho Co., Ltd.) at 230°C and a load of 21.18 N.

[0023] 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. It is preferable that the weight-average molecular weight Mw of the polypropylene resin is above the lower limit above, as this allows for sufficient resin fluidity, makes it easier to control the thickness of the cast raw material sheet, and facilitates the production of a film suitable for a core layer that is accurately stretched in the width direction. It is also preferable that the weight-average molecular weight Mw of the polypropylene resin is below the upper limit above, as this makes it easier to improve the mechanical properties of the resulting sheet, and allows for the production of a film suitable for a core layer that is inexpensive and has improved stretchability.

[0024] 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 higher, and more preferably 4.5 or higher. A molecular weight distribution (Mw / Mn) of the polypropylene resin that is above the lower limit of the above limit is preferable because it allows for sufficient generation of β-crystals in the cast raw material sheet before stretching, making it easier to obtain appropriate strength as a core layer. There is no particular upper limit to the molecular weight distribution (Mw / Mn) of the polypropylene resin, but it is preferably 10 or lower.

[0025] 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 restrictions on the GPC instrument used in the GPC method; commercially available high-temperature GPC analyzers capable of molecular weight analysis of polyolefins (for example, the HLC-8121GPC-HT, a high-temperature GPC analyzer with a built-in differential refractometer (RI), manufactured by Tosoh Corporation) can be used. In this case, measurements can be performed using the GPC column, column temperature, eluent, and flow rate described in the examples, for example. Typically, a calibration curve is prepared using standard polystyrene, and the weight-average molecular weight (Mw) and number-average molecular weight (Mn) are obtained by converting them to polystyrene equivalents.

[0026] The thickness of the core 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 laminated film according to this embodiment as a protective film for build-up films used in the manufacture of electronic components, a core layer thickness of 50% to 93% of the total thickness of the laminated film is recommended. The thickness of the core layer can be measured by cutting the laminated film and observing the cross-section with a microscope.

[0027] (Skin layer) The skin layer is laminated on at least one side of the core layer. In the laminated film according to this embodiment, it is sufficient that at least one surface is composed of the surface of the skin layer.

[0028] In the laminated film according to this embodiment, the core layer is in contact with the surface of the object to be protected, thereby effectively protecting the object. 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 is in contact with the core layer, and the film is wound together with the base film to form a winding body, when a physical external force is applied to the winding body, the occurrence of winding misalignment between the protective film and the base film of the winding body can be effectively suppressed.

[0029] Furthermore, the skin layer may be laminated on both sides of the core layer. In the laminated film according to this embodiment, since both sides of the surface are composed of the surface of the skin layer, the skin layer of the laminated film can suitably protect the object to be protected, and furthermore, it is possible to suitably suppress the occurrence of winding misalignment between the protective film and the base film of the winding body. 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.

[0030] 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. Preferably, the layer different from the skin layer is also made of polypropylene resin.

[0031] The skin layer comprises a propylene elastomer (a1) and a propylene copolymer. Specifically, the skin layer can be formed from a resin composition (A) comprising a propylene elastomer (a1), an ethylene-propylene block copolymer (a2), and an ethylene-propylene random copolymer (a3).

[0032] In the skin layer, the mass ratio of the propylene elastomer (a1), ethylene-propylene block copolymer (a2), and ethylene-propylene random copolymer (a3) ​​(propylene elastomer (a1): ethylene-propylene block copolymer (a2): ethylene-propylene random copolymer (a3)) is not particularly limited. However, from the viewpoint of optimizing the surface properties of the skin layer (such as the coefficient of dynamic friction) and reducing the deposition of ethylene components on the roll surface during the film manufacturing process, thereby favorably exhibiting the effects of the present invention, the ratio 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.

[0033] The content of propylene elastomer (a1), ethylene-propylene block copolymer (a2), and ethylene-propylene random copolymer (a3) ​​in the skin layer is not particularly limited, but from the viewpoint of fully exhibiting the effects of the present invention, it is preferable that the propylene 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 contamination of the roll surface with ethylene components, it is more preferable that the propylene 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 winding misalignment, it is even more preferable that the amount of propylene-based elastomer (a1) is in the range of 15 to 55 parts by mass, ethylene-propylene block copolymer (a2) is in the range of 30 to 70 parts by mass, and ethylene-propylene random copolymer (a3) ​​is in the range of 15 to 55 parts by mass.

[0034] Similarly, the content of the propylene 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 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). Furthermore, from the viewpoint of effectively suppressing the contamination of the roll surface with ethylene components, it is more preferable that the content of the propylene 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 winding misalignment, it is even more preferable that the propylene-based elastomer (a1) is in the range of 15-55% by mass, a2 is in the range of 30-70% by mass, and ethylene-propylene random copolymer (a3) ​​is in the range of 15-55% by mass.

[0035] The propylene-based elastomer (a1) used in composition (A) is a propylene-ethylene-α-olefin ternary polymer containing propylene-derived structural units, ethylene-derived structural units, and α-olefin-derived structural units 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.

[0036] Examples of the propylene-based elastomer (a1) used in composition (A) include propylene-ethylene-1-butene copolymers. A copolymer is preferred in which the propylene-based elastomer (a1) contains 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.

[0037] The propylene-based elastomer (a1) used in composition (A) is preferably a copolymer with an ethylene content of 1 to 15% by mass, and more preferably a copolymer with an ethylene content of 3 to 12% by mass.

[0038] The propylene-based elastomer (a1) used in composition (A) is preferably a copolymer with a 1-butene content of 1 to 15% by mass, and more preferably a copolymer with a 1-butene content of 1 to 12% by mass.

[0039] For propylene-based elastomer (a1), the MFR is preferably 3 to 14 g / 10 min, and more preferably 5 to 12 g / 10 min, in terms of moldability.

[0040] The ethylene-propylene block copolymer (a2) used in composition (A) is preferably a block copolymer with an ethylene content of 1 to 15% by mass, and more preferably a block copolymer with an ethylene content of 3 to 12% by mass.

[0041] For ethylene-propylene block copolymer (a2), the MFR is preferably 3 to 12 g / 10 min, and more preferably 5 to 10 g / 10 min, in terms of moldability.

[0042] The weight-average molecular weight (Mw) of the ethylene-propylene block copolymer (a2) is not particularly limited, but is preferably between 200,000 and 600,000, and more preferably between 300,000 and 500,000. Furthermore, 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 higher, and more preferably 5 or higher. The methods for measuring these weight-average molecular weight (Mw) and number-average molecular weight (Mn) are the same as those described for the polypropylene resin.

[0043] The ethylene-propylene random copolymer (a3) ​​used in composition (A) is preferably a random copolymer with an ethylene content of 0.5 to 6% by mass, and more preferably a random copolymer with an ethylene content of 1 to 5% by mass.

[0044] For ethylene-propylene random copolymer (a3), the MFR is preferably 5 to 14 g / 10 min, and more preferably 7 to 12 g / 10 min, in terms of moldability.

[0045] The weight-average molecular weight (Mw) of the ethylene-propylene random copolymer (a3) ​​is not particularly limited, but is preferably between 200,000 and 600,000, and more preferably between 300,000 and 500,000. Furthermore, 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 higher, and more preferably 5 or higher. The methods for measuring these weight-average molecular weight (Mw) and number-average molecular weight (Mn) are the same as those described for the polypropylene resin.

[0046] In the laminated 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.

[0047] In this embodiment, the total content of ethylene and butene in the skin layer of the laminated film may be 8.0% by mass or more. From the viewpoint of favorably regulating the surface properties of the skin layer (such as the coefficient of dynamic friction) and reducing the deposition of ethylene components on the roll surface during the film manufacturing process, thereby favorably exhibiting 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, and more preferably in the range of 8.0 to 25.0% by mass. Also from a similar viewpoint, the ethylene content 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. Furthermore, from a similar 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 content in the skin layer originates from the ethylene units and butene units contained in the propylene-based elastomer (a1), ethylene-propylene block copolymer (a2), and ethylene-propylene random copolymer (a3). The ethylene and butene content in the skin layer are determined using a nuclear magnetic resonance spectrometer or the like. More specifically in this invention, a Bruker AVANCE NEO700 is used, and the observed nucleus is: 13 Measurements are taken at C (176.08 MHz).

[0048] The measurement mode is reverse-gated decoupling (quantitative method), the shift criterion is 5 chains of propylene units (mmmm) (21.95 ppm), the number of cumulative measurements is 2048, and the temperature is 130°C.

[0049] Furthermore, 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 "GJ Ray et al., Macromolecules 1977, 10, pp. 773-778" and "Y.-D. Zhang et al., Polym. J. 2003, 35, pp. 551-559". The total ethylene and butene content in the skin layer was calculated by measuring the ethylene content and butene content of each resin used to form the skin layer using the method described above, and considering the blending ratio of each resin in the skin layer. It is a value.

[0050] The laminated film according to this embodiment is obtained by cutting a single-layer cast raw material sheet of composition (A) into strips, and measuring the loss tangent tanδ at a vibration frequency of 1 Hz and a temperature of 20°C using a dynamic viscoelastic device, wherein the loss tangent tanδ 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 suitably exhibit the effects of the present invention described above.

[0051] For a single-layer cast raw material sheet of composition (A), strips measuring 40 mm in the longitudinal direction and 8 mm in the transverse direction are cut, 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.

[0052] [loss tangent tanδ] Dynamic viscoelasticity was measured using a dynamic viscoelasticity measuring instrument (for example, a "viscoelasticity measuring device (model: DMS6100)" manufactured by Seiko Instruments Inc.). A single-layer skin cast raw material sheet made of composition (A) was cut into strips, and the temperature dependence of the single-layer skin cast raw material sheet made of composition (A) was measured according to JIS-K7244 (1999 edition) under measurement conditions of tensile mode, vibration frequency of 1 Hz, chuck distance of 20 mm, and heating rate of 5 °C / min. From these measurement results, the loss loss tangent tanδ at 20 °C was determined from the temperature dispersion of the loss loss tangent.

[0053] The laminated film according to this embodiment has a coefficient of kinetic friction of 1.0 or more when measured by overlapping the surface of the skin layer and a biaxially stretched polyester film at 5.56 gf / cm 2 Furthermore, the coefficient of kinetic friction when measured by overlapping the surface of the skin layer and a biaxially stretched polyester film at 33.33 gf / cm 2 is 1.0 or more. Since the surface of the skin layer of the laminated film according to this embodiment has such surface characteristics, it is possible to preferably exhibit the effects of the present invention described above.

[0054] Regarding the surface of the skin layer, the kinetic frictional force D1 at 5.56 gf / cm 2 and the kinetic frictional force D2 at 33.33 gf / cm 2 are measured by the following frictional force measurement methods respectively. A more specific measurement method employs the method described in the examples.

[0055] [Frictional force] Use a surface property measuring machine (for example, "HEIDON Tribogear (Model: TYPE14FW)" manufactured by Shinto Kagaku Co., Ltd.) to measure various frictional forces. Cut out the laminated film into a test film with a length of 20 cm in the longitudinal direction and a width of 3 cm in the transverse direction. Next, set the test film on a 30 mm flat indenter (contact area 9 cm 2 ) in a non-wrinkled state. At this time, set the test film so that the skin layer is on the outside. Next, a biaxially stretched 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 expansion ratio (Sdr) 0.000%, core level difference (Sk) 0.002 μm, protrusion valley height (Svk) 0.001 μm, protrusion valley space volume (Vvv) 0.000 ml / m 2 , core space volume (Vvc) 0.001 ml / m 2 , core volume (Vmc) 0.001 ml / m 2A piece of biaxially oriented polyester film (with a maximum height (Sz) of 0.08 μm and a thickness of 50 μm) is cut to a length of 20 cm in the vertical direction and 8 cm in the horizontal direction. It is then placed on a movable table so that the untreated side, which has not undergone surface modification treatment such as corona discharge, is facing upwards, ensuring that it is wrinkle-free. The biaxially oriented 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%. It is used in contact with the skin layer to measure the static and dynamic friction coefficients.

[0056] In this state, the surface of the skin layer of the test film and the biaxially oriented polyester film are superimposed and measured, yielding 5.56 gf / cm². 2 The coefficient of dynamic friction D1 under pressure is calculated with a table speed of 100 mm / min and a vertical load of 50 gf (pressure equivalent value of 5.56 gf / cm²). 2 Measurements are taken with a displacement of 60 mm or more (one-way movement), a data sampling rate of 50 ms, a measurement temperature of 23°C, and a measurement humidity of 50% RH. From the values ​​obtained from each of the three measurements, the dynamic friction coefficient D1 (average value between displacements of 1 and 60 mm) is extracted.

[0057] Furthermore, the surface of the skin layer of the test film and the biaxially oriented polyester film are superimposed and measured at 33.33 gf / cm². 2 The coefficient of dynamic friction D2 under pressure is calculated as follows: table speed 100 mm / min, vertical load 300 gf (pressure equivalent value 33.33 gf / cm²). 2 Measurements are taken with a displacement of 60 mm or more (one-way movement), a data sampling rate of 50 ms, a measurement temperature of 23°C, and a measurement humidity of 50% RH. From the values ​​obtained from each of the three measurements, the dynamic friction coefficient D2 (average value between displacements of 1 and 60 mm) is extracted.

[0058] The laminated film of this embodiment is preferably a surface-roughened laminated film in which the surface of the skin layer is roughened. Specifically, from the viewpoint of exhibiting the effects of the present invention described above even more favorably, the surface roughness of the skin layer of the laminated film of this embodiment preferably satisfies at least one of the following (a) to (e), more preferably two or more, even more preferably three or more, and particularly preferably all of them.

[0059] (a) The root mean square height (Sq) is between 0.48 and 1.12 μm. (b) The surface area ratio (Sdr) of the interface is 0.54 to 3.01%. (c) The level difference (Sk) of the core is 1.03 to 2.78 μm. (d) The height of the protruding peak (Spk) is 0.68 to 1.42 μm. (e) The height of the protruding valley (Svk) is 0.17 to 0.64 μm.

[0060] The aforementioned physical properties relating to the surface roughness of the skin layer are measured by the following surface roughness measurement method. More specifically, the measurement method described in the examples is adopted.

[0061] [Surface roughness] An optical interferometry non-contact surface shape measuring instrument (for example, "VertScan2.0 (model: R5500GML)" manufactured by Ryoka Systems Co., Ltd.) is used. As a sample for measurement, a film is cut to an arbitrary size of about 20 cm square, and with the wrinkles sufficiently smoothed out, it is set on the measurement stage using an electrostatic contact plate or the like. First, the measurement is performed using WAVE mode, applying a 530 white filter and a 1×BODY microscope tube, and using a 10x objective lens, measuring one field of view (470 μm × 353 μm). This operation is performed at 10 locations on the surface of the skin layer of the target sample film at 1 cm intervals in the flow direction, starting from the center in both the flow direction and width direction. Next, the obtained data is subjected to noise reduction processing using a median filter (3×3), and then Gaussian filtering with a cutoff value of 176 μm is performed to remove the waviness component. This makes it possible to appropriately measure the surface condition of the skin layer. Next, the analysis is performed using the "ISO parameters" function in the "Bearing" plugin of the "VS-Viewer" analysis software for "VertScan2.0" to obtain Sq(μm), Sdr(%), Sk(μm), Spk(μm), and Svk(μm), and the average value of each of the values ​​obtained at the 10 locations mentioned above is calculated.

[0062] 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 oriented surface film according to this embodiment as a protective film for build-up films 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. Furthermore, the thickness of the skin layer is preferably 0.5% or more of the total thickness of the laminated film, more preferably 1% or more, even more preferably 3% or more, even more preferably 5% or more, and particularly preferably 10% or more. Furthermore, the thickness of the skin layer is preferably 50% or less of the total thickness of the biaxially oriented surface film, more preferably 30% or less, even more preferably 25% or less, even more preferably 20% or less, and particularly preferably 15% or less. When skin layers are formed on both sides of the laminated film according to this embodiment, it is preferable that the thickness of the skin layer on each side is within the thickness range described above. Furthermore, if skin layers are formed on both sides of the laminated film according to this embodiment, the thicknesses of each skin layer may be the same or different. The thickness of the skin layer can be measured by cutting the laminated film and observing the cross-section with a microscope.

[0063] The skin layer and core layer each preferably have an ash content of 100 ppm or less. Ash is caused by polymerization catalyst residue and other factors, and can lead to minute foreign matter (fish eyes). Fish eyes can be prevented if the ash content is 100 ppm or less, preferably 50 ppm or less. The ash content can be adjusted by controlling the type and amount of catalyst used during polymerization of the resins constituting the skin layer and core layer, respectively.

[0064] In this specification, the ash content of the skin layer and core layer is measured in accordance with ISO 3451-1 as follows: The resin forming the skin layer or 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 defined as the ash content.

[0065] The skin layer and core layer may each contain additives. The additives are not particularly limited, and known additives added to resin films can be used. Generally, additives used in polypropylene resins can be used. Examples of additives include antioxidants, chlorine absorbers, UV absorbers and other stabilizers, lubricants, plasticizers, flame retardants, antistatic agents, and colorants. Such additives may be added to the skin layer or core layer to the extent that they do not impair the effects of the present invention. However, from the viewpoint of suitably utilizing the biaxially oriented surface film according to this embodiment as a protective film for build-up films used in the manufacture of electronic components, it is preferable not to add components to the skin layer that may transfer to the protected component and affect its properties, such as antiblocking agents.

[0066] The laminated film according to this embodiment can be suitably used as a protective film for the adhesive layer of build-up films used in the manufacture of electronic components. Furthermore, the laminated film can also be used as a protective film in various fields, such as in the manufacturing process of thermosetting resin components like fiber-reinforced plastics.

[0067] The laminated film according to this embodiment can be obtained, for example, by extruding a resin composition that forms the core layer and the skin layer, thereby obtaining a film in which the core layer and the skin layer are laminated. For example, when manufacturing a laminated film as a biaxially oriented laminated film, it can be manufactured by a process (i) of manufacturing a cast raw material sheet in which the core layer and the skin layer are laminated before stretching by extruding a resin composition that forms the core layer and the skin layer, and a process (ii) of biaxially stretching the cast raw material sheet. Specific examples of steps (i) and (ii) are illustrated below.

[0068] In step (i), first, the resin compositions forming the core layer and the skin layer are melt-kneaded in an extruder at 200-260°C, then combined in a confluencer and extruded from a T-die. At this time, it is preferable to remove coarse foreign matter from each resin using a polymer filter upstream of the confluencer.

[0069] The merging process can be carried out using known methods such as a method performed in the pipe before the T-die, a method using a lamination unit provided at the resin introduction section of the T-die (feed block method), or a method of laminating resin after widening within the T-die (manifold lamination method). Among these, the manifold lamination method is superior in terms of lamination thickness accuracy, but economic considerations and other factors can be taken into account, and the appropriate method can be selected from these options.

[0070] Next, the laminate with two or more layers extruded in this manner is pressed tightly onto at least one metal drum (cooling drum) whose drum surface is controlled to 20-100°C using an air knife to form a sheet, for example, to obtain a cast raw material sheet with a thickness of 500-5000 μm.

[0071] Next, in step (ii), a biaxially oriented laminated film can be manufactured by performing a stretching treatment on the cast raw material sheet before stretching. Biaxial stretching in the length direction (also referred to as longitudinal, vertical, or MD) and the width direction (also referred to as transverse, or TD) is preferred for this stretching treatment, but biaxial stretching in an oblique direction may also be used if necessary.

[0072] Stretching methods include the tubular method, the tenter method, and stretching between rolls with a difference in peripheral speed. These methods allow for simultaneous biaxial stretching or sequential biaxial stretching. Since biaxially oriented laminated films with no thickness variations and good flatness are easily obtained, simultaneous biaxial stretching using the tenter method, sequential biaxial stretching using the tenter method, and sequential biaxial stretching in which the film is stretched in the flow direction between rolls with a difference in peripheral speed and then stretched in the width direction using the tenter method are preferred.

[0073] In the sequential biaxial stretching method, for example, the cast raw material sheet is first kept at a temperature of 100-160°C and passed between rolls with a speed difference, or guided to a tenter, where it is stretched 3-8 times in the flow direction, and then relaxed by 0-10% as needed. Subsequently, the uniaxially stretched film is guided to a tenter and stretched 6-12 times in the width direction at a temperature of 120-185°C, then relaxed by 0-10% as needed, heat-set, and wound up.

[0074] In the simultaneous biaxial stretching method, the cast raw material sheet is guided to a tenter and stretched to the aforementioned stretch ratio in the flow direction and width direction at a temperature of 120-185°C. After that, it is relaxed by about 0-10% as needed and heat-set. Then, the edges of the resulting biaxially oriented laminated film are trimmed as needed and wound up.

[0075] <2. Laminate> The laminate according to this embodiment is a laminate utilizing the laminated film according to this embodiment. The laminate according to this embodiment has a structure in which a base film, an adhesive layer, and the aforementioned laminated film according to this embodiment are laminated in this order.

[0076] The laminated film according to this embodiment is as described above.

[0077] Furthermore, in the laminate according to this embodiment, the laminated film according to this embodiment protects the adhesive layer formed on the base film. The material and thickness of the base film and 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 epoxy resin, which serves as a encapsulant for electronic substrates) and a protective film are laminated on a base film such as polyethylene terephthalate film. When the winding body according to this embodiment is a winding body of build-up film, it is preferable that the base film is polyethylene terephthalate film and the adhesive layer is formed of an uncured or semi-cured epoxy resin.

[0078] The thickness of the base film is not particularly limited, but is typically around 10 to 150 μm. The thickness of the adhesive layer is also not particularly limited, but is typically greater than or equal to the conductor thickness of the inner circuit board to be laminated, typically around conductor thickness + (10 to 120) μm.

[0079] Furthermore, when the laminated film according to this embodiment is 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.

[0080] There are no particular restrictions on the thickness of the laminate, but it is typically around 50 to 450 μm.

[0081] <3. Roll body> The winding body according to this embodiment is a winding body of a laminate utilizing the laminated film according to this embodiment. For example, it can be a winding body in which a build-up film including the laminated film of this embodiment is wound. The laminate constituting the winding body is as described in the section <2. Laminate> above, and has a structure in which a base film, an adhesive layer, and the laminated film according to this embodiment described above are laminated in this order, with the adhesive layer and one side of either the skin layer or core layer of the laminated film in contact with each other. The laminate is also in a form wound on a core.

[0082] The laminated film according to this embodiment is as described above.

[0083] Furthermore, in the winding body according to this embodiment, the laminated film according to this embodiment protects the adhesive layer formed on the base film. The material and thickness of the base film and thermosetting resin are appropriately selected according to the application of the winding body according to this embodiment (specifically, the application of the aforementioned laminate in the form of a winding body). For example, build-up films used in the manufacture of electronic components have a laminated structure in which an adhesive layer (an uncured or semi-cured thermosetting resin such as epoxy resin, which serves as a encapsulant for electronic substrates) and a protective film are laminated on a base film such as polyethylene terephthalate film. When the winding body according to this embodiment is a winding body of build-up film, it is preferable that the base film is polyethylene terephthalate film and the adhesive layer is formed of an uncured or semi-cured epoxy resin.

[0084] The thicknesses of the base film and the adhesive layer are as described in section <2. Laminate> above.

[0085] Furthermore, as described above, when the laminated film according to this embodiment is 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.

[0086] The thickness of the laminate that makes up the winding body is as described in section <2. Laminate> above.

[0087] The core is cylindrical or cylindrical in shape, and the laminate is wound along the circumference of the core.

[0088] The material of the core is not particularly limited and can be plastic, fiber-reinforced plastic, paper, or metal (iron, stainless steel, aluminum, etc.) that is less prone to deformation. Among these, fiber-reinforced plastic is preferred because it is lightweight and has high strength. Examples of fiber-reinforced plastic cores include those made by forming carbon fibers or glass fibers into a cylindrical shape and then impregnating and curing them with a curable resin such as unsaturated polyester resin.

[0089] The size of the core can be set according to the desired size of the winding body. The outer diameter of the circular cross-section of the core can be, for example, about 50 to 200 mm, more preferably about 80 to 100 mm. [Examples]

[0090] 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 % refer to "parts by mass" and "mass%", respectively.

[0091] [Example 1] (Core layer) Only pellets of homopolypropylene (b1) (MFR = 3.5 g / 10 min at 230°C, 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 that forms the core layer.

[0092] (Skin layer) A propylene-based elastomer (a1) (MFR = 6.0 g / 10 min at 230°C, ethylene content 0.49% by mass (calculated from measured ethylene content of 14.2 mol%), butene content 0.34% by mass (calculated from measured butene content of 4.9 mol%)), an ethylene-propylene block copolymer (a2) (MFR = 8.0 g / 10 min at 230°C, ethylene content 10.27% by mass (calculated from measured ethylene content of 16.2 mol%)), and an ethylene-propylene random copolymer (a3) ​​(MFR = 10 g / 10 min at 230°C, ethylene content 0.20% by mass (calculated from measured ethylene content of 6.0 mol%)) were dry-blended in the proportions shown in Table 1, and then melt-kneaded at 230°C using a kneading extruder to form pellets. Next, the pellets were fed from the hopper into extruder II and melted to prepare a resin composition that forms a skin layer.

[0093] [Fabrication of laminated films] Resin compositions (A) and (B) forming the skin layer and core layer were each extruded through a polymer filter at 230°C from a multi-manifold die to form a laminated film with a two-type, three-layer structure of skin layer / core layer / skin layer. The film was then cooled and solidified on a cooling drum with a surface temperature adjusted to 45°C, while being pressed with air pressure using an air knife, to obtain a cast raw material sheet with a thickness of 920 μm. Next, the cast raw material sheet was heated to 130°C in contact with metal rolls, and then stretched approximately 4.6 times in the flow direction between rolls with different peripheral speeds. Then, the uniaxially oriented film was introduced into a hot air oven while being held in clips and preheated to 180°C, and then stretched approximately 10 times in the width direction. Subsequently, it was heat-set at 170°C while being relaxed by approximately 10% in the width direction, to continuously obtain a laminated film with a thickness of approximately 20 μm. The thickness of the skin layer is 2.5 μm, and the thickness of the core layer is 15 μm. After trimming the edges of the obtained laminated film, it was wound onto a core to obtain a roll of laminated film.

[0094] [Examples 2-8] In preparing the resin composition (A) that forms the skin layer in Example 1, a roll-shaped laminated film was obtained in the same manner as in Example 1, except that the mixing ratio was as shown in Table 1.

[0095] [Comparative Example 1] In preparing the resin composition for forming the skin layer in Example 1, a roll-shaped laminated film was obtained in the same manner as in Example 1, except that the propylene-based elastomer (a1) used in the skin layer was replaced with low-density polyethylene, and the blending ratio was as shown in Table 1.

[0096] [Comparative Example 2] In preparing the resin composition for forming the skin layer in Example 1, the propylene-based elastomer (a1) and ethylene-propylene random copolymer (a3) ​​used in the skin layer were omitted, and the entire resin composition was replaced with ethylene-propylene block copolymer (a2), resulting in the blending ratios shown in Table 1. Otherwise, a roll-shaped laminated film was obtained in the same manner as in Example 1.

[0097] [Comparative Example 3] In preparing the resin composition for forming the skin layer in Example 1, a roll-shaped laminated film was obtained in the same manner as in Example 1, except that the propylene-based elastomer (a1) used in the skin layer was omitted and replaced with ethylene-propylene block copolymer (a2) and ethylene-propylene random copolymer (a3), with the blending ratios shown in Table 1.

[0098] [Comparative Example 4] In preparing the resin composition for forming the skin layer in Example 1, the propylene-based elastomer (a1), ethylene-propylene block copolymer (a2), and ethylene-propylene random copolymer (a3) ​​used in the skin layer were omitted, and the entire resin composition was replaced with homopolypropylene (b1) (MFR = 3.5 g / 10 min at 230°C), with the blending ratios shown in Table 1. Otherwise, a roll-shaped laminated film was obtained in the same manner as in Example 1.

[0099] [Fabrication of single-layer skin cast raw material sheets] Each resin composition (A) forming the skin layer in the examples and comparative examples was extruded through a polymer filter at 230°C from a multi-manifold die to form a single-film cast raw material sheet consisting only of the skin layer. The sheets were then cooled and solidified on a cooling drum with a surface temperature adjusted to 45°C, while being pressed with air pressure using an air knife, to obtain a cast raw material sheet with a thickness of 150 μm. The cast raw material sheet was used for the measurement of the loss tangent tanδ described later.

[0100] [Measurement of molecular weight and molecular weight distribution] The weight-average molecular weight, number-average molecular weight, and molecular weight distribution of homopolypropylene are measured using size exclusion chromatography (SEC), and the details of the measurement conditions are as follows. Equipment: HLC-8321GPC / HT (Detector: Differential Refractometer (RI)) (Manufactured by Tosoh Corporation) Columns: TSKgel guardcolumnHHR(30)HT (7.5mm I.D. × 7.5cm) × 1 + TSKgel GMHHR-H(20)HT (7.8mm I.D. × 30cm) × 3 (Manufactured by Tosoh Corporation) Eluent: 1,2,4-Trichlorobenzene (for GPC, manufactured by Fujifilm Wako Pure Chemical Industries) + BHT (0.05%) Flow rate: 1.0mL / min Detection condition: polarization-(-) Injection volume: 0.3mL Column temperature: 140℃ Temperature: 40°C Sample concentration: 1 mg / mL Sample preparation: The sample was weighed, and dissolved in solvent (1,2,4-trichlorobenzene with 0.1% BHT added) by shaking at 140°C for 1 hour. The mixture was then filtered by heating through a 0.5 μm sintered filter. Calibration Curve: A calibration curve was created using a fifth-order approximation curve with 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 measuring instrument. The molecular weight distribution (Mw / Mn) was obtained using the values ​​of Mw and Mn. Furthermore, the molecular weight distribution (Mz / Mn) was obtained using the values ​​of Mz and Mn.

[0101] [loss tangent tanδ] As a dynamic viscoelasticity measuring instrument, a "Viscoelasticity Measuring Device (Model: DMS6100)" manufactured by Seiko Instruments Inc. was used. As a measurement sample, a single-layer cast raw material sheet of composition (A) was cut into strips measuring 40 mm in the longitudinal direction and 8 mm in the transverse direction, and the temperature dependence of the cast raw material sheet was measured under the measurement conditions shown below in accordance with JIS-K7244 (1999 edition). Test mode: Tensile mode Chuck spacing: 20mm Vibration frequency: 1Hz Distortion amplitude: 10μm Tension gain: 1.2 Initial force amplitude: 100 mN Temperature range: -60 to 150°C Heating rate: 5°C / min Measurement atmosphere: Under nitrogen Measurement thickness: The sheet thickness used was that specified in [Preparation of single-layer skin cast raw material sheet] above. From these measurement results, the loss tangent tanδ with a temperature dispersion of 20°C was determined. The results are shown in Table 1.

[0102] [Surface roughness] As an optical interferometry non-contact surface shape measuring instrument, we used the "VertScan2.0 (model: R5500GML)" manufactured by Ryoka Systems Co., Ltd. As measurement samples, each laminated film from the examples and comparative examples was cut to an arbitrary size of approximately 20 cm square, and after thoroughly smoothing out any wrinkles, it was set on the measurement stage using an electrostatic contact plate or the like. First, the measurement was performed using WAVE mode, with a 530 white filter and a 1×BODY microscope tube applied, and a 10x objective lens was used to measure one field of view (470 μm × 353 μm). This operation was performed at 10 locations on the surface of the skin layer of the target sample film at 1 cm intervals in the flow direction, starting from the center in both the flow direction and width direction. Next, the obtained data was subjected to noise reduction processing using a median filter (3×3), and then Gaussian filtering with a cutoff value of 176 μm was performed to remove the waviness component. This made it possible to appropriately measure the surface condition of the skin layer. Next, we performed an analysis using the "ISO parameters" function in the "Bearing" plugin of the "VS-Viewer" analysis software for "VertScan2.0" to obtain Sq(μm), Sdr(%), Sk(μm), Spk(μm), and Svk(μm), and calculated the average value of each value obtained at the 10 locations mentioned above. The results are shown in Table 1.

[0103] [Frictional force] A HEIDON Tribogear (Model: TYPE14FW) manufactured by Shinto Kagaku Co., Ltd. was used as the surface texture measuring instrument. Each laminated film of the examples and comparative examples was cut into strips of 20 cm in the vertical direction and 3 cm in the horizontal direction to be used as test films. Next, the test films were subjected to a 30 mm flat indenter (contact area 9 cm) while remaining wrinkle-free. 2The film was set in the ) and positioned so that the skin layer of the test film faced outwards. Next, a biaxially oriented polyester film was used to measure the frictional force of the skin layer (arithmetic mean height (Sa) 0.001 μm, root mean square height (Sq) 0.001 μm, root mean square slope (Sdq) 0.001, interface area expansion ratio (Sdr) 0.000%, core level difference (Sk) 0.002 μm, protruding valley height (Svk) 0.001 μm, protruding valley space volume (Vvv) 0.000 ml / m 2 Core space volume (Vvc) 0.001 ml / m³ 2 The volume of the core (Vmc) is 0.001 ml / m³. 2 A piece of material (maximum height (Sz) 0.08 μm, thickness 50 μm) was cut into a 20 cm vertical and 8 cm horizontal section, and placed on a movable table with the untreated side (without surface modification treatment such as corona discharge) facing upwards, ensuring it was wrinkle-free.

[0104] In this state, the surface of the skin layer of the test film and the biaxially oriented polyester film are superimposed and measured, yielding 5.56 gf / cm². 2 The coefficient of dynamic friction force D1 under pressure is calculated with a table speed of 100 mm / min and a vertical load of 50 gf (pressure equivalent value 5.56 gf / cm²). 2 Measurements were taken with a displacement of 60 mm or more (one-way movement), a data sampling rate of 50 ms, a measurement temperature of 23°C, and a measurement humidity of 50% RH. From the values ​​obtained from each of the three measurements, the dynamic friction coefficient D1 (average value between displacements of 1 and 60 mm) was extracted. The results are shown in Table 1.

[0105] Furthermore, the surface of the skin layer of the test film and the biaxially oriented polyester film are superimposed and measured at 33.33 gf / cm². 2 The kinetic friction force D2 under pressure is calculated with a table speed of 100 mm / min and a vertical load of 300 gf (pressure equivalent value 33.33 gf / cm²). 2 Measurements were taken with a displacement of 60 mm or more (one-way movement), a data sampling rate of 50 ms, a measurement temperature of 23°C, and a measurement humidity of 50% RH. From the values ​​obtained from three measurements, the kinetic friction force D2 (average value between displacements of 1 and 60 mm) was extracted. The results are shown in Table 1.

[0106] [Evaluation of winding misalignment of the winding body] A base film with an adhesive layer (580 mm wide x 300 m long, non-silicone PET separator film, adhesive layer: epoxy adhesive (thermosetting resin)) was prepared. Laminates were prepared by bonding the base film and each laminate film together so that the skin layer of each laminated film (slit to 580 mm wide) prepared in the examples and comparative examples was in contact with the adhesive layer of the base film, and these laminates were used as evaluation samples. The evaluation samples were wound around a core (620 mm long, 92.5 mm in diameter) at a speed of 50 m / min to form a winding body. Next, the winding body was packed into a cardboard box, and after a vibration test (level 3) according to the method specified in JIS-Z0232, the difference in unevenness of the film roll end face was evaluated in four stages: "Excellent: A+", "Good: A", "Average: B", and "Poor: C". A score of "Average: B" or higher was considered acceptable, and the following criteria were used for evaluation. The results are shown in Table 1. A+: The difference in unevenness on the film roll end surface is between 0mm and 1.0mm. A: The difference in unevenness on the end face of the film roll is greater than 1.0 mm and less than or equal to 3.0 mm. B: The difference in unevenness on the end face of the film roll is greater than 3.0 mm but less than or equal to 5.0 mm. C: The difference in unevenness on the end face of the film roll exceeds 5.0 mm.

[0107] [Roller soiling evaluation] The ethylene component contamination on the roll surface was assessed by cleaning the longitudinal stretching rolls before the start of film formation, and visually observing the contamination status one hour after the start of film formation. The difference in the condition of the longitudinal stretching roll surface was evaluated on a four-point scale: "Excellent: A+", "Good: A", "Average: B", and "Poor: C". A score of "Average: B" or higher was considered acceptable, and the following criteria were used for evaluation. The results are shown in Table 1. A+: No change from before film formation. A: There is almost no dirt. B: Very slight, faint stains can be seen. C: A cloudy white stain is clearly visible.

[0108] [Table 1]

Claims

1. A core layer made of composition (B) containing homopolypropylene (b1), A skin layer is formed on both sides of the core layer and consists of a composition (A) comprising a propylene-based elastomer (a1), an ethylene-propylene block copolymer (a2), and an ethylene-propylene random copolymer (a3), It is a laminated film having the following features: Both sides of the laminated film are composed of the surface of the skin layer, The content of the propylene elastomer (a1), the ethylene-propylene block copolymer (a2), and the ethylene-propylene random copolymer (a3) ​​in the skin layer is in the range of 5 to 65% by mass for the propylene 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). The propylene-based elastomer (a1) is 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. The MFR of the ethylene-propylene block copolymer (a2) at 230°C is 8.0 to 12 g / 10 min. The MFR of the ethylene-propylene random copolymer (a3) ​​at 230°C is 10 to 14 g / 10 min. Unlike the ethylene-propylene block copolymer (a2) and the ethylene-propylene random copolymer (a3), the propylene-based elastomer (a1) is different. The composition (A) contains butene, The composition (A) contains 5 to 40 parts by mass of the propylene elastomer (a1), 40 to 90 parts by mass of the ethylene-propylene block copolymer (a2), and 5 to 50 parts by mass of the ethylene-propylene random copolymer (a3). The composition (A) has a loss tangent tanδ of 0.06 or more at an 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% by mass or more and 35.0% by mass or less. The ethylene and butene content in the skin layer of the laminated film is derived from ethylene units and butene units contained in the propylene elastomer (a1), the ethylene-propylene block copolymer (a2), and the ethylene-propylene random copolymer (a3), respectively.

2. The laminated film according to claim 1, wherein the propylene-based elastomer (a1) is a propylene-ethylene-α-olefin ternary polymer comprising a propylene-derived structural unit, an ethylene-derived structural unit, and an α-olefin-derived structural unit having 4 to 20 carbon atoms.

3. The laminated film according to claim 1 or 2, wherein the composition (A) has an ethylene content of 7.6% by mass or more and 25.0% by mass or less.

4. A laminated film according to any one of claims 1 to 3, used as a protective film for the adhesive layer of a build-up film.

5. A winding body comprising a build-up film containing a laminated film according to any one of claims 1 to 3, wound around it.

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