Laminated Film

Abstract

To provide a new laminated film, the meandering and wrinkling of which on a conveyance roll in a film processing process and the winding deviation of which when being wound into a film roll is suppressed, and which, when being wound as a protective film of an adhesive layer together with a base film into a winding body and a physical external force is applied to the winding body, allows the winding deviation between the protective film and the base film of the winding body to be suitably suppressed.SOLUTION: A laminated film comprises a core layer and a skin layer laminated on at least one side of the core layer. The skin layer comprises an ethylene-propylene block copolymer and an ethylene-propylene random copolymer. The ethylene content in the skin layer is 4.5 mass% or more and 40 mass% or less. A static friction force A1 at a pressure of 5.56 gf / cm2, measured by overlaying a surface of the skin layer of the laminated film and a biaxially oriented polyester film, is 3.30 gf / cm2 or more and 5.50 gf / cm2 or less. The rate of change of a ratio of a dynamic friction force B at a pressure of 33.33 gf / cm2 to the static friction force A2 at a pressure of 33.33 gf / cm2, measured by overlaying the surface of the skin layer of the laminated film and the biaxially oriented polyester film: (1+ (dynamic friction force B - static friction force A2) / static friction force A2)×100 is 110% or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a laminated film, specifically to a laminated film having a core layer and a skin layer, which is used as a protective film for a build-up film used in the manufacture of electronic components, for example. [Background technology]

[0002] Polypropylene films are widely used as industrial material films, including for packaging, due to their light weight, thermal stability, and excellent mechanical properties. In particular, in recent years, polypropylene films have been widely used as protective materials and release materials in the manufacturing processes of electronic components and electronic substrates, thermosetting resin members such as fiber-reinforced plastics, and photosensitive films, taking advantage of their low surface energy. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6354634 [Patent Document 2] Japanese Patent Application Publication No. 2018-204002 [Patent Document 3] Japanese Patent Application Publication No. 1-121332 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, polypropylene films are used as protective films to protect the adhesive layer in build-up films used in the manufacture of electronic components (build-up films have a laminate structure in which a base film (such as a PET film), an adhesive layer (an uncured or semi-cured thermosetting resin that serves as a sealant for electronic substrates), and a protective film are laminated together), and these build-up film rolls are wound, stored, distributed, and used. In such build-up films, a protective film is laminated on the adhesive layer applied to the base film, and in the winding process, the adhesive layer (an uncured or semi-cured thermosetting resin) is soft, so 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 to prevent the thermosetting resin from protruding. However, in the transport process of the build-up film roll, for example, there is a problem in that the protective film (polypropylene film) included in the roll and the base film are likely to become misaligned due to vibrations from the conveyor.

[0005] To improve processability, polypropylene films are commonly modified with antiblocking agents to adjust friction. However, polypropylene films used in build-up films have limitations on the addition of antiblocking agents, as they may affect the insulating performance of the thermosetting resin (insulating material used to seal electronic substrates) that they come into contact with. Specifically, if an antiblocking agent is added to create an irregular surface, the antiblocking agent present on the polypropylene film surface may fall off and transfer to the thermosetting resin when the polypropylene film (protective film) is peeled off from the thermosetting resin. The thermosetting resin layer thickness in the areas where the antiblocking agent has transferred to the thermosetting resin surface may be thinner than in other areas, potentially resulting in a decrease in insulating performance. For this reason, there is a problem with the addition of fine particles, such as antiblocking agents, to polypropylene films used in build-up films.

[0006] To obtain a frictional force suitable for processing polypropylene films, surface modification treatment using corona discharge has been performed on the surface of polypropylene films. However, corona discharge treatment alone can cause the film to meander on the transport roll, wrinkles, and even misalignment at the end of the roll on which the polypropylene film is wound.

[0007] As a polypropylene film that does not contain an antiblocking agent or the like and has been given appropriate winding properties, 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). Such a polypropylene film is considered suitable for processability as a workpiece. However, when the film described in Patent Document 1 is used as a protective film for a build-up film, the roughened film surface reduces the contact area with the opposing substrate film (e.g., PET film) due to air entrainment during winding, which makes it less likely for winding slippage to occur. However, on the other hand, the roughened film surface reduces the actual contact area with the highly smooth opposing substrate film (e.g., PET film). This creates a problem of winding slippage easily occurring between the protective film (polypropylene film) and the substrate film (e.g., PET film) due to vibrations during transport of the wound build-up film.

[0008] Furthermore, as a film imparted with slipperiness (static friction coefficient, dynamic friction coefficient, ratio of dynamic friction coefficient to static friction coefficient, etc.), a polyethylene-based film is known in which a low friction coefficient is obtained by incorporating high-density polyethylene, etc., with a polyethylene-based resin composition that has few terminal branches that become adhesion points (Patent Document 2). Such polypropylene films are also considered suitable for processability as work-in-progress. However, the film described in Patent Document 2 employs a control means for lowering the friction coefficient, making it unsuitable for preventing shear when a physical external force is applied to the wound body.

[0009] Furthermore, a technology has been proposed for preventing film meandering, wrinkling, and winding slippage during processing of polypropylene film, in which at least one side of the film is subjected to vertical stripe-shaped corona discharge treatment in which corona discharge-treated areas of 5 to 30 mm width and non-treated areas of 5 to 50 mm width are alternately positioned (Patent Document 3). However, with the technology described in Patent Document 3, it is difficult to adjust the widths of the corona discharge-treated and non-treated areas, and it is therefore unsuitable as a technology for preventing film meandering, wrinkling, and winding slippage during the processing of polypropylene film.

[0010] The primary object of the present invention is to provide a novel laminate film that suppresses film meandering and wrinkling on conveyor rolls during film processing and winding shear when wound onto a film roll. Furthermore, when the laminate film is used as a protective film for a pressure-sensitive adhesive layer and wound together with a substrate film to form a wound body, shear between the protective film and the substrate film of the wound body is suitably suppressed when a physical external force is applied to the wound body. The laminate film can be suitably used as a protective film for the pressure-sensitive 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 in the manufacturing process of thermosetting resin members (pressure-sensitive adhesive layers) such as fiber-reinforced plastics. Another object of the present invention is to provide a novel wound body using the laminate film that suppresses shear. [Means for solving the problem]

[0011] The present inventors conducted extensive research to solve the above-mentioned problems. As a result, they found that in a laminate film comprising a core layer and a skin layer laminated on at least one side of the core layer, by forming the skin layer from a predetermined resin composition, setting the ethylene content in the skin layer within a predetermined range, and further controlling the static friction and kinetic friction on the surface of the skin layer, meandering and wrinkling of the film on a conveying roll during the film processing step and winding slippage when wound onto a film roll can be suppressed. Furthermore, when the protective film for the PSA layer is wound together with a base film to form a wound body, winding slippage between the protective film and the base film of the wound body can be suitably suppressed when a physical external force is applied to the wound body. The present invention was completed through further research based on these findings.

[0012] That is, the present invention includes the following. Item 1. A core layer and a skin layer laminated on at least one side of the core layer; A laminated film comprising: the skin layer comprises an ethylene-propylene block copolymer and an ethylene-propylene random copolymer; the ethylene content in the skin layer is 4.5% by mass or more and 40% by mass or less, 5.56 gf / cm measured by overlapping the surface of the skin layer of the laminated film with a biaxially oriented polyester film. 2 The static friction force A1 under pressure is 3.30gf / cm 2 More than 5.50gf / cm 2 is as follows: 33.33 gf / cm 2 measured by overlapping the surface of the skin layer of the laminated film with a biaxially oriented polyester film. 2 Static friction force A2 under pressure: 33.33gf / cm 2 A laminated film in which the rate of change in the proportion of kinetic friction force B when pressure is applied: (1 + (kinetic friction force B - static friction force A2) ÷ static friction force A2) × 100 is 110% or more. Item 2. The laminated film according to Item 1, wherein the skin layer contains polyethylene. Item 3. The laminate film according to Item 1 or 2, wherein the skin layers are laminated on both sides of the core layer. Item 4. The laminate film according to any one of items 1 to 3, which is used to protect a pressure-sensitive adhesive layer. Item 5. A laminate comprising a base film, a pressure-sensitive adhesive layer, and the laminate film according to any one of Items 1 to 4 laminated in this order. Item 6. A roll of a laminate in which a base film, a pressure-sensitive adhesive layer, and the laminate film according to any one of Items 1 to 4 are laminated in this order, the pressure-sensitive adhesive layer is in contact with one surface of either the skin layer or the core layer of the laminated film, The laminate is wound around a core. [Effects of the Invention]

[0013] According to the present invention, a novel laminate film can be provided that suppresses film meandering and wrinkling on conveyor rolls during film processing and winding shear when wound onto a film roll. Furthermore, when the laminate film is wound together with a substrate film as a protective film for a pressure-sensitive adhesive layer to form a wound body, winding shear between the protective film and the substrate film of the wound body is suitably suppressed when a physical external force is applied to the wound body. Such a laminate film can be suitably used, for example, as a protective film for a build-up film used in the manufacture of electronic components. Another object of the present invention is to provide a novel wound body that uses the laminate film and in which winding shear is suppressed. The wound body can be configured as a wound body for a build-up film for electronic components. DETAILED DESCRIPTION OF THE INVENTION

[0014] 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 skin layer contains an ethylene-propylene block copolymer and an ethylene-propylene random copolymer. The ethylene content in the skin layer is in the range of 4.5 to 40% by mass. The surface of the skin layer of the laminated film is placed over a biaxially oriented polyester film, and the surface has a viscosity of 5.56 gf / cm. 2 The static friction force A1 under pressure is 3.30gf / cm 2 More than 5.50gf / cm 2 Furthermore, the surface of the skin layer of the laminated film is overlapped with a biaxially stretched polyester film, and the measured value is 33.33 gf / cm 2 Static friction force A2 under pressure: 33.33gf / cm 2 The rate of change in the proportion of kinetic friction force B when pressure is applied: (1 + (kinetic friction force B - static friction force A2) ÷ static friction force A2) × 100 is 110% or more. The laminate film according to this embodiment has these characteristics, and thereby can exhibit the effect of the present invention described above, namely, "the occurrence of meandering and wrinkles in the film on the transport roll during the film processing step, and the occurrence of winding slippage when wound onto a film roll are suppressed, and further, when the film is wound together with a base film as a protective film for the pressure-sensitive adhesive layer to form a wound body, the occurrence of winding slippage between the protective film and the base film in the wound body is suitably suppressed when a physical external force is applied to the wound body."

[0015] The roll according to the present embodiment is a roll of a laminate that uses the laminate film according to the present embodiment as a protective film, and is a laminate in which a base film, a pressure-sensitive adhesive layer, and the laminate film according to the present embodiment are laminated in this order, with the pressure-sensitive adhesive layer and either the skin layer or the core layer of the laminate film being in contact with each other, and the laminate is wound around a core. The roll according to the present embodiment uses the laminate film according to the present embodiment as a protective film, and therefore, 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 is suitably suppressed.

[0016] The laminate film according to this embodiment and the rolled body using the laminate film are described in detail below. In this specification, the term "to" in a numerical range means "at least" or "not more than." That is, the expression "α to β" means "at least α and not more than β" or "at least β and not more than α," and includes both α and β as a range.

[0017] <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.

[0018] 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.

[0019] The laminate film according to this embodiment is preferably a stretched laminate film, more preferably a biaxially stretched laminate film.

[0020] (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.

[0021] Examples of polypropylene resins suitable for forming the core layer include propylene homopolymers, copolymers of propylene and ethylene, and copolymers 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 polypropylene homopolymer alone or a mixture of two or more polypropylene homopolymers, as this facilitates increasing the mechanical strength and heat resistance of the core layer and also enables the core layer surface to be appropriately roughened.

[0022] 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.

[0023] 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 the polypropylene resin equal to or greater than the lower limit described above is preferred because sufficient resin fluidity is obtained, the thickness of the cast raw sheet is easily controlled, and a film that is precisely stretched in the width direction is easily produced. Furthermore, a melt flow rate of the polypropylene resin equal to or less than the upper limit described above is preferred because the mechanical properties and stretchability of the resulting sheet are easily improved. In this specification, the MFR of the resin can be measured in accordance with JIS K-7210 (1999) using a melt flow indexer (e.g., a melt indexer manufactured by Toyo Seiki Seisakusho, Ltd.) at 230°C and a load of 21.18 N.

[0024] The weight-average molecular weight (Mw) of the polypropylene resin is preferably 200,000 to 600,000, 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 precisely stretched in the width direction is easily produced, which is preferable. Furthermore, when the weight-average molecular weight Mw of the polypropylene resin is equal to or less than the upper limit, the mechanical properties and stretchability of the resulting sheet are easily improved, and a film suitable for a core layer is easily obtained, which is preferable.

[0025] 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, more preferably 4.5 or more. When the molecular weight distribution (Mw / Mn) of the polypropylene resin is equal to or greater than the lower limit, β crystals can be sufficiently generated in the cast raw sheet before stretching, which is preferable because it is easy to obtain 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.

[0026] The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of a 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 commercially available high-temperature GPC analyzers capable of analyzing the molecular weight of polyolefins (e.g., Tosoh Corporation's HLC-8121GPC-HT high-temperature GPC analyzer with built-in differential refractometer (RI)) can be used. In this case, measurements can be performed using the GPC column, column temperature, eluent, and flow rate described in the Examples. Typically, a calibration curve is prepared using standard polystyrene, and the weight-average molecular weight (Mw) and number-average molecular weight (Mn) are calculated in terms of polystyrene.

[0027] 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% to 93% 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.

[0028] (skin layer) The skin layer is laminated on at least one side of the core layer. In the laminate according to this embodiment, at least one surface may be constituted by the surface of the skin layer. The laminate film according to this embodiment can suitably protect the object to be protected by having the core layer come into contact with the surface of the object to be protected. Furthermore, by designing the skin layer to face the transport roll during the processing of the laminate film, meandering and wrinkles of the laminate film on the transport roll during the processing of the laminate film, and winding slippage when wound onto a film roll are suppressed. Furthermore, when the adhesive layer applied to the substrate film as a protective film for the adhesive layer is wound together with the substrate film so that the adhesive layer and the core layer come into contact with each other to form a wound body, when a physical external force is applied to the wound body, winding slippage between the protective film and the substrate film of the wound body is suitably suppressed.

[0029] The skin layers may be laminated on both sides of the core layer. In the laminate according to this embodiment, since both surfaces are constituted by the surfaces of the skin layers, the object to be protected can be suitably protected on either surface of the laminate, and the occurrence of meandering and wrinkles of the laminate film on the conveying roll during the processing step of the laminate film and winding slippage when wound onto the film roll can be suppressed, and the occurrence of winding slippage between the protective film and the substrate film of the wound body can also be suitably suppressed. In addition, 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 the present 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. The layer different from the skin layer is also preferably made of a polypropylene resin.

[0031] The skin layer includes an ethylene-propylene block copolymer and an ethylene-propylene random copolymer. Specifically, the skin layer can be formed from a resin composition including an ethylene-propylene block copolymer and an ethylene-propylene random copolymer.

[0032] In the skin layer, the mass ratio of the ethylene-propylene block copolymer to the ethylene-propylene random copolymer (ethylene-propylene block copolymer:ethylene-propylene random copolymer) is not particularly limited, but from the viewpoint of improving the surface characteristics of the skin layer (such as the static friction coefficient and dynamic friction coefficient described below) and optimally exhibiting the effects of the present invention, it is preferably about 10:90 to 90:10, more preferably about 30:70 to 70:30, even more preferably about 35:65 to 65:35, and particularly preferably about 40:60 to 60:40.

[0033] The ethylene content of the ethylene-propylene block copolymer in the skin layer is not particularly limited, as long as the ethylene content in the skin layer is within the range of 4.5 to 40.0% by mass, but from the viewpoint of improving the surface properties of the skin layer (such as the static and dynamic friction coefficients described below) and optimally exhibiting the effects of the present invention, it is preferably about 1.0 to 15.0% by mass, more preferably about 3.0 to 12.0% by mass, even more preferably about 3.0 to 10.0% by mass, and particularly preferably 3.0 to 8.0% by mass. From the same viewpoint, the ethylene content of the ethylene-propylene random copolymer is preferably about 0.5 to 6.0% by mass, more preferably about 1.0 to 5.0% by mass, even more preferably about 1.5 to 4.5% by mass, and particularly preferably 1.5 to 3.0% by mass.

[0034] From the viewpoint of improving the surface properties of the skin layer and optimally exhibiting the effects of the present invention, the melt flow rate (MFR) of the ethylene-propylene block copolymer is preferably 3.0 g / 10 min to 12.0 g / 10 min, more preferably 5.0 g / 10 min to 10.0 g / 10 min. From the same viewpoint, the melt flow rate (MFR) of the ethylene-propylene random copolymer is preferably 5.0 g / 10 min to 14.0 g / 10 min, more preferably 7.0 g / 10 min to 12.0 g / 10 min. The method for measuring MFR is as described above.

[0035] The weight-average molecular weight (Mw) of the ethylene-propylene block copolymer is not particularly limited, but is preferably 200,000 to 600,000, more preferably 300,000 to 500,000, and 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, more preferably 5 or more. The weight-average molecular weight (Mw) of the ethylene-propylene random copolymer is not particularly limited, but is preferably 200,000 to 600,000, more preferably 300,000 to 500,000, and 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, more preferably 5 or more. The methods for measuring these weight-average molecular weights (Mw) and number-average molecular weights (Mn) are the same as those for the polypropylene resin described above.

[0036] The skin layer preferably contains polyethylene in addition to the ethylene-propylene block copolymer and the ethylene-propylene random copolymer. When the skin layer contains polyethylene in addition to the ethylene-propylene block copolymer and the ethylene-propylene random copolymer, the surface properties (static friction coefficient, dynamic friction coefficient, etc., which will be described later) of the skin layer become better, and the effects of the present invention can be suitably exhibited. As the polyethylene, low-density polyethylene (for example, polyethylene having a density of 0.91 to 0.93 g / cm 3about), high density polyethylene (for example, density 0.94 to 0.96 g / cm 3 From the viewpoint of more suitably exhibiting the effects of the present invention described above, low-density polyethylene is preferred.

[0037] When the skin layer contains polyethylene, the proportion of polyethylene is not particularly limited, as long as the ethylene content in the skin layer is in the range of 4.5 to 40 mass%, but is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, per 100 parts by mass of the ethylene-propylene block copolymer and the ethylene-propylene random copolymer in total, and the lower limit is preferably 5 parts by mass or more.

[0038] Furthermore, from the viewpoint of improving the surface properties of the skin layer and optimally exerting the effects of the present invention, the total content of the ethylene-propylene block copolymer, ethylene-propylene random copolymer, and polyethylene in the skin layer is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 98% by mass or more.

[0039] In the laminate film according to this embodiment, the ethylene content in the skin layer may be in the range of 4.5 to 40% by mass. From the viewpoint of improving the surface properties of the skin layer (such as the static and dynamic friction coefficients described below) and optimally exhibiting the effects of the present invention, the ethylene content in the skin layer is preferably 10 to 36% by mass, more preferably 11 to 36% by mass, even more preferably 12 to 36% by mass, even more preferably 12 to 25% by mass, and particularly preferably 12 to 20% by mass. The ethylene content in the skin layer is mainly derived from ethylene units contained in the ethylene-propylene block copolymer, ethylene-propylene random copolymer, and polyethylene. The ethylene content in the skin layer is determined using a nuclear magnetic resonance spectrometer or the like. More specifically, in the present invention, an AVANCE NEO700 manufactured by Bruker is used, and the observation nucleus is 13 Measured at C (176.08 MHz).

[0040] The measurement mode was reverse gated decoupling (quantitative method), the shift standard was 5-propylene unit chain (mmmm) (21.95 ppm), the number of accumulations was 2048, and the temperature was 130°C.

[0041] The ethylene unit content (mol%) was calculated from the signal integration value of methylene carbon based on head-to-tail bond diads, 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 ethylene content in the skin layer was calculated by measuring the ethylene content of each resin 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.

[0042] The laminated film according to this embodiment has a modulus of 5.56 gf / cm when measured by overlapping the surface of the skin layer with the biaxially oriented polyester film. 2 The static friction force A1 under pressure is 3.30gf / cm 2 More than 5.50gf / cm 2 Furthermore, the surface of the skin layer is overlapped with a biaxially stretched polyester film, and the measured value is 33.33 gf / cm 2 Static friction force A2 under pressure: 33.33gf / cm 2 The rate of change in the proportion of dynamic friction force B when pressure is applied: (1 + (dynamic friction force B - static friction force A2) ÷ static friction force A2) × 100 is 110% or more. The laminated film according to this embodiment has such surface properties on the surface of the skin layer, and therefore is able to suitably exhibit the effects of the present invention described above.

[0043] From the viewpoint of more suitably exhibiting the above-mentioned effects of the present invention, 5.56 gf / cm 2 The lower limit of the static friction force A1 under pressure is preferably 3.00 gf / cm 2 More preferably, 3.20 gf / cm 2 More preferably, 3.30 gf / cm 2The upper limit is preferably 5.35 gf / cm 2 Less than or equal to 5.20 gf / cm 2 or less, more preferably 5.10 gf / cm 2 The following are included:

[0044] In order to more effectively exert the effects of the present invention, the hardness of the tensile strength is set to 33.33 gf / cm 2 Static friction force A2 under pressure: 33.33gf / cm 2 The lower limit of the rate of change of the ratio of the kinetic friction force B when pressure is applied is preferably 115% or more, and the upper limit is preferably 190% or less. 2 The static friction force A2 under pressure is not particularly limited as long as the above rate of change is satisfied, but is preferably 12.00 to 25.00 gf / cm 2 Also, 33.33gf / cm 2 The dynamic friction force B under pressure is not particularly limited as long as the above rate of change is satisfied, but is preferably 15.00 to 45.00 gf / cm 2 The degree of

[0045] 5.56gf / cm for the surface of the skin layer 2 Static friction force A1 under pressure: 33.33gf / cm 2 Static friction force A2 under pressure, and 33.33 gf / cm 2 The dynamic friction force B under pressure is measured by the following friction force measurement method. Note that a more specific measurement method is the method described in the examples.

[0046] [Frictional force] Various friction 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 pressed against a 30 mm flat indenter (contact area 9 cm) without any wrinkles. 2) at this time, the skin layer of the test film is set 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 development 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) used for measuring the friction force of the skin layer was 2 , space volume of the core (Vvc) 0.001 ml / m 2 , core volume (Vmc) 0.001 ml / m 2 A biaxially oriented polyester film (with an arithmetic mean height Sa (ISO 25178) of 0.001 μm, a maximum height Sz (ISO 25178) of 0.08 μm, and a thickness of 50 μm) was cut into a length of 20 cm lengthwise and 8 cm widthwise, and placed on a movable table with the untreated side, which had not been subjected to surface modification treatments such as corona discharge, facing up. The biaxially oriented polyester film had an arithmetic mean height Sa (ISO 25178) of 0.001 μm, a maximum height Sz (ISO 25178) of 0.08 μm, a thickness (JIS C-2318) of 50 μm, a static coefficient of friction (JIS K-7125) of 0.46, a dynamic coefficient of friction (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 was used to measure the static and dynamic coefficients of friction by contacting the skin layer.

[0047] In this state, the surface of the skin layer of the test film and the biaxially stretched polyester film are overlapped and measured, and the strength is 5.56 gf / cm 2 The static friction force A1 under pressure is calculated using a table speed of 100 mm / min and a vertical load of 50 gf (equivalent to a pressure of 5.56 gf / cm 2 ), displacement of 60 mm or more (one-way movement), data sampling rate of 50 ms, measurement temperature of 23°C, measurement humidity of 50% RH. From the values obtained from each of the three measurements, extract the static friction force A1 (maximum value between displacements of 0 and 1 mm).

[0048] In addition, the surface of the skin layer of the test film and a biaxially stretched polyester film are overlapped and measured, and the strength is 33.33 gf / cm 2The static friction force A2 under pressure is 33.33 gf / cm 2 The dynamic friction force B under pressure is a table speed of 100 mm / min and a vertical load of 300 gf (equivalent to a pressure of 33.33 gf / cm 2 ), displacement of 60 mm or more (one-way movement), data sampling rate every 50 ms, measurement temperature 23°C, measurement humidity 50% RH. From the values obtained from each of the three measurements, extract static friction force A2 (maximum value between displacements of 0 and 1 mm) and kinetic friction force B (kinetic friction force peak (maximum value between displacements of 1 and 60 mm)). Using the extracted static friction force A2 and kinetic friction force peak B, calculate the rate of change in the ratio of kinetic friction force B to static friction force A2 using the formula = (1 + (kinetic friction force B - static friction force A2) ÷ static friction force A2) x 100 (%).

[0049] In order to more effectively exert the effects of the present invention described above, it is preferable that the surface roughness of the skin layer satisfy at least one of the following (a) to (i), more preferably two or more, even more preferably three or more, and particularly preferably all of them.

[0050] (a) The arithmetic mean height (Sa) is 0.06 to 0.38 μm. (b) The root mean square height (Sq) is 0.09 to 0.50 μm. (c) The root mean square slope (Sdq) is 0.07 to 0.24. (d) The interface area development ratio (Sdr) is 0.21 to 2.39%. (e) The level difference (Sk) of the core portion is 0.17 to 1.18 μm. (f) The protruding valley height (Svk) is 0.05 to 0.36 μm. (g) The spatial volume of the protruding valley (Vvv) is 0.01 to 0.04 ml / m 2 is. (h) The core volume (Vvc) is 0.10 to 0.64 ml / m 2 is. (i) The core volume (Vmc) is 0.06 to 0.42 ml / m 2 is.

[0051] The above-mentioned physical property relating to the surface roughness of the skin layer is measured by the following surface roughness measuring method. Note that, as a more specific measuring method, the method described in the Examples is adopted.

[0052] [Surface roughness] A non-contact optical interferometric surface profiler (e.g., the VertScan 2.0 (model R5500GML) manufactured by Ryoka Systems Co., Ltd.) is used. The film is cut into a desired size (approximately 20 cm square) for measurement. After smoothing out any wrinkles, it is placed on the measurement stage using an electrostatic contact plate or similar. Measurements are first performed in WAVE mode using a 530 white filter, a 1x BODY lens barrel, and a 10x objective lens, measuring a field of view (470 μm x 353 μm). This procedure is repeated for 10 locations, spaced 1 cm apart in the machine direction, starting from the center of the surface of the skin layer in both the machine and cross directions. The resulting data is then subjected to a median filter (3x3) to remove noise, followed by a Gaussian filter with a cutoff value of 30 μm to remove waviness. This allows for accurate measurement of the skin layer surface condition. Next, analysis was performed using the "ISO parameters" in the plug-in function "Bearing" of the analysis software "VS-Viewer" of "VertScan2.0", and Sa (μm), Sq (μm), Sdq (μm), Sdr (%), Sk (μm), Svk (μm), Vvv (ml / m 2 ), Vvc(ml / m 2 ), Vmc(ml / m 2 ) and calculate the average value of each value obtained at the above 10 locations.

[0053] The thickness of the skin 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, 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. 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 particularly preferably 10% or more of the total thickness of the laminate film. 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 particularly preferably 15% or less of the total thickness of the laminate 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 skin layers are formed on both sides of the laminate film according to the present embodiment, the thicknesses of the respective skin layers may be the same or different from each other. The thickness of the skin layer can be measured by cutting the laminate film and observing the cross section with a microscope.

[0054] 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 matter (fisheyes). If the ash content is 100 ppm or less, preferably 50 ppm or less, fisheyes can be prevented. The ash content can be adjusted by controlling the type and amount of catalyst used during polymerization of the resins that make up the skin layer and the core layer, respectively.

[0055] In this specification, the ash content of the skin layer and the core layer is measured in accordance with ISO 3451-1 as follows: The resin forming 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.

[0056] The skin layer and the core layer may contain additives. The additives are not particularly limited, and known additives added to resin films can be used. Additives commonly used in polypropylene resins can be used. Examples of additives include stabilizers such as antioxidants, chlorine absorbers, and ultraviolet absorbers, as well as 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 perspective of suitably using the laminate 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 to the skin layer components that may migrate to the protected component and affect the properties of the protected component, such as antiblocking agents.

[0057] The laminate film according to the present embodiment can be suitably used as a protective film for the pressure-sensitive adhesive layer of a build-up film used in the manufacture of electronic components, etc. The laminate film can also be used as a protective film in various fields, such as in the manufacturing process of thermosetting resin members such as fiber-reinforced plastics.

[0058] The laminate film according to the present embodiment can be obtained as a film in which a core layer and a skin layer are laminated, for example, by extrusion molding a resin composition that forms the core layer and the skin layer. For example, when producing a biaxially stretched laminate film, the laminate film can be produced by extrusion molding a resin composition that forms the core layer and the skin layer, followed by step (i) of producing a cast raw sheet in which a pre-stretched core layer and a pre-stretched skin layer are laminated, and step (ii) of biaxially stretching the cast raw sheet. Specific examples of step (i) and step (ii) are shown below.

[0059] In step (i), the resin compositions forming the core layer and the skin layer are melt-kneaded at 200 to 260°C in extruders, respectively, and then joined in a joining device and extruded through a T-die. At this time, it is preferable to remove large foreign matter from each resin using a polymer filter upstream of the joining device.

[0060] The joining can be performed by known methods such as a method in which the joining is performed in a pipe upstream of the T-die, a method in which the joining is performed using a lamination unit provided in the resin inlet section of the T-die (feed block method), a method in which the resin is laminated after being widened in the T-die (manifold lamination method), etc. Of these, the manifold lamination method is superior in terms of lamination thickness accuracy, but an appropriate method can be selected from these methods taking into consideration economic efficiency, etc.

[0061] Next, the thus extruded laminate consisting of two or more layers is pressed against at least one metal drum (cooling drum) whose drum surface is controlled to 75 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 5000 μm.

[0062] Next, in step (ii), the unstretched cast raw sheet is stretched to produce a biaxially stretched laminate film. The stretching is preferably biaxial stretching in the machine (longitudinal, also called MD) direction and the width (transverse, also called TD) direction, but may also be biaxial stretching in an oblique direction if necessary.

[0063] Stretching methods include a tubular method, a tenter method, and a method of stretching between rolls with different peripheral speeds, and biaxial stretching can be performed simultaneously or sequentially. Since a biaxially stretched laminate film with no thickness unevenness and good flatness can be easily obtained, simultaneous biaxial stretching by a tenter method, sequential biaxial stretching by a tenter method, and sequential biaxial stretching in which stretching in the machine direction between rolls with different peripheral speeds is followed by stretching in the width direction by a tenter method are preferred.

[0064] In the sequential biaxial stretching method, for example, a cast raw sheet is first kept at a temperature of 100 to 160°C, passed between rolls with a speed difference, or introduced into a tenter, and stretched 3 to 8 times in the machine direction, and then relaxed by about 0 to 10% as needed. Subsequently, the uniaxially stretched film is introduced into a tenter and stretched 6 to 12 times in the width direction at a temperature of 120 to 180°C, and then relaxed by about 0 to 10% as needed, heat-set, and wound up.

[0065] 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 180°C, and then relaxed by about 0 to 10% as necessary and heat-set. Thereafter, the edges of the obtained biaxially stretched laminate film are trimmed as necessary and then wound up.

[0066] <2. Laminate> The laminate according to the present embodiment is a laminate using the laminate film according to the present embodiment, 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.

[0067] The laminated film according to this embodiment is as described above.

[0068] Furthermore, in the laminate according to the present embodiment, the laminate film according to the present embodiment protects the pressure-sensitive adhesive layer formed on the base film. The materials and thicknesses of the base film and the thermosetting resin are each appropriately selected depending on the application of the laminate according to the present embodiment. For example, a build-up film used in the manufacture of electronic components has a laminate configuration in which a pressure-sensitive adhesive layer (an uncured or semi-cured thermosetting resin such as an epoxy resin that serves as a sealant for electronic substrates) and a protective film are laminated on a base film such as a polyethylene terephthalate film. When the roll according to the present embodiment is used as a roll of build-up film, it is preferable that the base film is a polyethylene terephthalate film and the pressure-sensitive adhesive layer is formed of an uncured or semi-cured epoxy resin.

[0069] The thickness of the base film is not particularly limited, but is, for example, about 10 to 150 μm. The thickness of the pressure-sensitive adhesive layer is also not particularly limited, but is, for example, at least the thickness of the conductor of the inner layer circuit board to be laminated, and is, for example, about the conductor thickness + (10 to 120) μm.

[0070] Furthermore, 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 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.

[0071] The thickness of the laminate is not particularly limited, but is, for example, about 50 to 450 μm.

[0072] <3. Roll body> The roll according to this embodiment is a roll of a laminate using the laminate film according to this embodiment. The laminate constituting the roll is as explained in the section <2. Laminate> above, and has a configuration in which a base film, a pressure-sensitive adhesive layer, and the laminate film according to this embodiment described above are laminated in this order, with the pressure-sensitive adhesive layer coming into contact with either the skin layer or the core layer of the laminate film. The laminate is in a form wound around a core.

[0073] The laminated film according to this embodiment is as described above.

[0074] Furthermore, in the roll according to the present embodiment, the laminate film according to the present embodiment protects the pressure-sensitive adhesive layer formed on the base film. The materials and thicknesses of the base film and the thermosetting resin are each appropriately selected depending on the application of the roll according to the present embodiment (specifically, the application of the aforementioned laminate in the form of a roll). For example, a build-up film used in the manufacture of electronic components has a laminate configuration in which a pressure-sensitive adhesive layer (an uncured or semi-cured thermosetting resin such as an epoxy resin that serves as a sealant for electronic substrates) and a protective film are laminated on a base film such as a polyethylene terephthalate film. When the roll according to the present 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 pressure-sensitive adhesive layer is formed of an uncured or semi-cured epoxy resin.

[0075] The thicknesses of the base film and the pressure-sensitive adhesive layer are as described above in the section <2. Laminate>.

[0076] Furthermore, 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.

[0077] The thickness of the laminate constituting the roll is as described above in the section <2. Laminate>.

[0078] The winding core is cylindrical or columnar, and the laminate is wound around the winding core in the circumferential direction.

[0079] The material of the core is not particularly limited, and examples thereof include plastics that are less prone to deformation, fiber-reinforced plastics, paper, and metals (iron, SUS, aluminum, 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 molding carbon fiber, glass fiber, etc. into a cylindrical shape and impregnating and curing a curable resin such as unsaturated polyester resin.

[0080] The size of the winding core can be set according to the size of the intended 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. [Example]

[0081] The present invention will be described in detail below with reference to examples and comparative examples. However, the present invention is not limited to these examples. Unless otherwise specified, parts and % represent "parts by mass" and "% by mass", respectively.

[0082] [Example 1] (core layer) Pellets of homopolypropylene (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) alone were fed from the hopper into extruder I and melted to prepare a resin composition for forming the core layer.

[0083] (skin layer) Low-density polyethylene (MFR at 230°C = 0.3 g / 10 min), an ethylene-propylene block copolymer (MFR at 230°C = 8.0 g / 10 min, ethylene content of 11.42 mass% (calculated from a measured ethylene content of 16.2 mol%)), and an ethylene-propylene random copolymer (MFR at 230°C = 10 g / 10 min, ethylene content of 4.08 mass% (calculated from a measured ethylene content of 6.0 mol%)) were dry-blended in the ratios shown in Table 1, melt-kneaded at 230°C using a kneading extruder, and pelletized. The pellets were then fed from a hopper into Extruder II and melted to prepare a resin composition for forming a skin layer.

[0084] (Preparation of laminated film) The resin compositions forming the skin and core layers were each extruded through a polymer filter at 230°C from a multi-manifold die to form a laminate film with a three-layer structure (skin layer / core layer / skin layer). The extruded film was then pressed onto a cooling drum (the surface temperature of which was adjusted to 90°C) using an air knife to cool and solidify the film, resulting in a 920 μm-thick cast raw sheet. The cast raw sheet was then heated to 153°C while in contact with a metal roll and stretched approximately 4.6 times in the machine direction between rolls with different peripheral speeds. The uniaxially stretched film was then clamped and introduced into a hot air oven, preheated to 180°C, stretched approximately 10 times in the width direction, and subsequently heat-set at 170°C with approximately 10% relaxation in the width direction to continuously obtain a biaxially stretched laminate film with a thickness of approximately 20 μm. The skin layer thickness was 2.5 μm, and the core layer thickness was 15 μm. The ends of the obtained biaxially stretched laminate film were trimmed, and then the film was wound around a core to obtain a roll of biaxially stretched laminate film.

[0085] [Examples 2 to 3] In preparing the resin composition for forming the skin layer of Example 1, except that the compounding ratios shown in Table 1 were used, the same procedure as in Example 1 was repeated to obtain rolled biaxially stretched laminate films.

[0086] [Examples 4 to 5] In preparing the resin composition forming the skin layer of Example 1, the low-density polyethylene used in the skin layer was changed to high-density polyethylene (MFR at 230°C = 0.04 g / 10 min), and the compounding ratio was set as shown in Table 1. Except for this, roll-shaped biaxially oriented laminate films were obtained in the same manner as in Example 1.

[0087] [Examples 6 to 7] In preparing the resin composition forming the skin layer of Example 1, a roll-shaped biaxially oriented laminate film was obtained in the same manner as in Example 1, except that the low-density polyethylene used in the skin layer was not blended and the blending ratio was as shown in Table 1.

[0088] [Comparative Example 1] A roll-shaped biaxially oriented 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 of Example 1, the low-density polyethylene, ethylene-propylene block copolymer, and ethylene-propylene random copolymer used in the skin layer were not blended, and the entire resin composition was replaced with homopolypropylene (MFR at 230°C = 3.5 g / 10 min).

[0089] Comparative Example 2 The easily adhesive side of a biaxially stretched polyester film (Cosmoshine (registered trademark) A4100, manufactured by Toyobo Co., Ltd., thickness 50 μm) was used as the skin layer surface, and it was used as a general film with a highly smooth film surface.

[0090] [Comparative Examples 3 to 4] In preparing the resin composition for forming the skin layer of Example 4, except that the compounding ratios shown in Table 1 were used, the same procedure as in Example 4 was carried out to obtain rolled biaxially stretched laminate films.

[0091] Comparative Example 5 A roll of biaxially stretched laminate film was obtained in the same manner as in Example 1, except that the resin composition for forming the skin layer of Example 1 was prepared in the blending ratio shown in Table 1.

[0092] [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 detailed measurement conditions were 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 (Tosoh Corporation) Eluent: 1,2,4-trichlorobenzene (Fujifilm Wako Pure Chemical Industries, Ltd., for GPC) + BHT (0.05%) Flow rate: 1.0mL / min Detection condition: polarity-(-) Injection volume: 0.3mL Column temperature: 140℃ System temperature: 40°C Sample concentration: 1 mg / mL Sample pretreatment: The sample was weighed, dissolved in a solvent (1,2,4-trichlorobenzene with 0.1% BHT) and shaken at 140°C for 1 hour, then filtered through a 0.5µm sintered filter. Calibration curve: A calibration curve was created using a quintic approximation curve of standard polystyrene from 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 the analytical software for the measurement device. The molecular weight distribution (Mw / Mn) was obtained using the values of Mw and Mn. The molecular weight distribution (Mz / Mn) was also obtained using the values of Mz and Mn.

[0093] [Surface roughness] We used a Ryoka Systems Corporation VertScan 2.0 (Model: R5500GML) optical interference non-contact surface profiler. The film was cut into a desired size (approximately 20 cm square) for measurement. After smoothing out any wrinkles, the film was placed on the measurement stage using an electrostatic contact plate. Measurements were first performed in WAVE mode using a 530 white filter, a 1x BODY lens barrel, and a 10x objective lens, measuring a field of view (470 μm × 353 μm). This procedure was repeated for 10 locations, spaced 1 cm apart in the machine direction from the center of the skin layer surface in both the machine and cross directions. The resulting data was then subjected to a median filter (3 × 3) to remove noise, followed by a Gaussian filter with a cutoff value of 30 μm to remove waviness. This allowed for accurate measurement of the skin layer surface condition. Next, analysis was performed using the "ISO parameters" in the plug-in function "Bearing" of the analysis software "VS-Viewer" of "VertScan2.0", and Sa (μm), Sq (μm), Sdq (μm), Sdr (%), Sk (μm), Svk (μm), Vvv (ml / m 2 ), Vvc(ml / m 2 ), Vmc(ml / m 2 The average value of each value obtained at the 10 locations was calculated. The results are shown in Table 1.

[0094] [Frictional force] The surface property measuring device used was a "HEIDON Tribogear (Model: TYPE14FW)" manufactured by Shinto Scientific Co., Ltd. Each film prepared in 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 pressed against a 30 mm flat indenter (contact area 9 cm) without any wrinkles. 2) at the time, the skin layer of the test film was set 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 development 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) used for measuring the friction force of the skin layer was 2 , space volume of the core (Vvc) 0.001 ml / m 2 , core volume (Vmc) 0.001 ml / m 2 The specimen (maximum height (Sz) 0.08 μm, thickness 50 μm) was cut into a length of 20 cm and a width of 8 cm, and placed on a movable table without any wrinkles, with the untreated side that had not been subjected to surface modification treatment such as corona discharge facing up.

[0095] In this state, the surface of the skin layer of the test film and the biaxially stretched polyester film are overlapped and measured, and the strength is 5.56 gf / cm 2 The static friction force A1 under pressure is calculated using a table speed of 100 mm / min and a vertical load of 50 gf (equivalent to a pressure of 5.56 gf / cm 2 Measurements were taken at 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. The static friction force A1 (maximum value between 0 and 1 mm of displacement) was extracted from the values obtained from each of the three measurements.

[0096] In addition, the surface of the skin layer of the test film and a biaxially stretched polyester film are overlapped and measured, and the strength is 33.33 gf / cm 2 The static friction force A2 under pressure is 33.33 gf / cm 2 The dynamic friction force B under pressure is a table speed of 100 mm / min and a vertical load of 300 gf (equivalent to a pressure of 33.33 gf / cm 2Measurements were taken at 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 static friction force A2 (maximum value between 0 and 1 mm of displacement) and the kinetic friction force B (peak kinetic friction force (maximum value between 1 and 60 mm of displacement)) were extracted. Using the extracted static friction force A2 and peak kinetic friction force B, the rate of change in the ratio of kinetic friction force B to static friction force A2, which is used as an index of winding slippage prevention, was calculated using the formula: (1 + (kinetic friction force B - static friction force A2) ÷ static friction force A2) × 100 (%). The results are shown in Table 1.

[0097] [Evaluation of film meandering and wrinkles] Each film (1200 mm wide) prepared in the Examples and Comparative Examples was slit into a 580 mm wide x 1500 m roll using a slitter at a normal speed of 300 m / min and at a speed of 400 m / min, at which film meandering and wrinkling are likely to occur. After slitting, the film on the transport roll was visually inspected for meandering and wrinkling and evaluated according to the following criteria. The results are shown in Table 1. A: The film is neither meandering nor wrinkled. B: No film meandering or wrinkles. However, film meandering and wrinkles may occur as the speed increases. C: Either film meandering or wrinkles are present.

[0098] [Winding misalignment evaluation] Each film was slit in the same manner as described above in [Evaluation of Film Meandering and Wrinkles], measuring 580 mm wide x 1500 m, and wound around a core (620 mm long, 92.5 mm diameter) at a speed of 300 m / min to form a film roll. The unevenness of the end surface of the resulting film roll was evaluated on a three-point scale: "Excellent (A)," "Fair (B)," and "Poor (C)." A grade of "Fair (B)" or higher was considered a pass, and the evaluation was based on the following criteria. The results are shown in Table 1. A: The unevenness of the edge of the film roll is 0 mm B: The unevenness of the edge of the film roll is more than 0 mm and 1.0 mm or less C: The unevenness of the film roll edge exceeds 1.0 mm

[0099] [Evaluation of winding misalignment of wound body] A substrate film having an adhesive layer (580 mm wide x 300 m, non-silicone PET separator film, adhesive layer: epoxy adhesive (thermosetting resin)) was prepared. Each film (slit to a width of 580 mm) prepared in the Examples and Comparative Examples was laminated with the substrate film so that the skin layer of the film came into contact with the adhesive layer of the substrate film, and this laminate 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. The roll was then packed in a cardboard box and subjected to a vibration test (level 3) according to the method specified in JIS-Z0232. After that, the unevenness of the film roll end surface was evaluated as "Excellent: A" and "Excellent: B". + The samples were evaluated on a four-point scale: "Good: A," "Average: B," and "Poor: C," with "Average: B" or higher being considered pass, and were evaluated according to the following criteria. The results are shown in Table 1. A + : The unevenness of the film roll edge is 0 mm to 1.0 mm A: The unevenness of the film roll edge is more than 1.0 mm and 3.0 mm or less B: The unevenness of the film roll edge is more than 3.0 mm and 5.0 mm or less C: The unevenness of the film roll edge exceeds 5.0 mm

[0100] [Table 1]

[0101] The laminate films of Examples 1 to 7 are laminate films comprising a core layer and a skin layer laminated on at least one side of the core layer, wherein the skin layer contains an ethylene-propylene block copolymer and an ethylene-propylene random copolymer, the ethylene content in the skin layer is 4.5% by mass or more and 40% by mass or less, and the surface of the skin layer of the laminate film is overlapped with a biaxially stretched polyester film, and the surface of the skin layer of the laminate film has a viscosity of 5.56 gf / cm 2 The static friction force A1 under pressure is 3.30gf / cm 2 More than 5.50gf / cm 2The surface of the skin layer of the laminated film is overlapped with a biaxially oriented polyester film, and the strength is 33.33 gf / cm 2 Static friction force A2 under pressure: 33.33gf / cm 2 The rate of change in the proportion of kinetic friction force B when pressure is applied: (1 + (kinetic friction force B - static friction force A2) ÷ static friction force A2) × 100, is 110% or more. The laminate films of Examples 1 to 7 are suppressed from meandering and wrinkling on the transport roll during the film processing step, and from slippage when wound onto a film roll. Furthermore, when the laminate films of Examples 1 to 7 are wound together with a base film as a protective film for the pressure-sensitive adhesive layer to form a wound body, slippage between the protective film and the base film of the wound body is suitably suppressed when a physical external force is applied to the wound body.

[0102] For example, as can be seen from the comparison between Example 1 and Example 4, between Example 2 and Example 5, and between Example 3 and Comparative Example 3, when high-density polyethylene is used instead of low-density polyethylene in the resin composition of the skin layer, the static friction forces A1 and A2, the kinetic friction force B, and the rate of change thereof all tend to decrease. However, the static friction force A1 is also easily affected by the content of ethylene-propylene random copolymer or ethylene-propylene block copolymer in the skin layer. For example, when the content of ethylene-propylene random copolymer or ethylene-propylene block copolymer is low, using high-density polyethylene instead of low-density polyethylene tends to strongly decrease the static friction force A1.

[0103] Furthermore, as can be seen from, for example, a comparison between Example 6 and Example 7, and a comparison between Example 3 and Comparative Example 5, increasing the proportion of ethylene-propylene block copolymer instead of ethylene-propylene random copolymer tends to decrease the static friction force A2 and the kinetic friction force B. On the other hand, the static friction force A1 and the rate of change are significantly affected by the content of low-density polyethylene or high-density polyethylene in the skin layer. When low-density polyethylene and high-density polyethylene are not included (when the content of low-density polyethylene and high-density polyethylene in the skin layer is 0% by mass (Examples 6 and 7)), increasing the proportion of ethylene-propylene block copolymer instead of ethylene-propylene random copolymer tends to decrease the static friction force A1 and increase the rate of change. Furthermore, when low-density polyethylene or high-density polyethylene is included (Example 3, Comparative Example 3), increasing the proportion of ethylene-propylene block copolymer instead of ethylene-propylene random copolymer tends to increase the static friction force A1 and decrease the rate of change.

[0104] Furthermore, as can be seen from the comparison between Example 1 and Example 2, the comparison between Example 1 and Example 3, and the comparison between Example 2 and Example 3, when the proportion of low-density polyethylene is increased in the skin layer instead of the ethylene-propylene block copolymer and the ethylene-propylene random copolymer, flexibility increases, and as a result, the kinetic frictional force B and the rate of change tend to increase.

[0105] Furthermore, as can be seen from the comparison between Example 7 and Example 5, and the comparison between Example 4 and Comparative Example 4 or Comparative Example 3, when the proportion of high-density polyethylene is increased in the skin layer instead of the ethylene-propylene block copolymer and the ethylene-propylene random copolymer, flexibility decreases, and as a result, the kinetic frictional force B and the rate of change tend to decrease.

[0106] Taking the above trends into consideration, the static friction forces A1, A2, kinetic friction force B, and the rate of change thereof can be controlled by appropriately adjusting the content of low-density polyethylene, high-density polyethylene, ethylene-propylene random copolymer, and ethylene-propylene block copolymer in the skin layer.

Claims

1. a core layer and a skin layer laminated on at least one side of the core layer; A laminated film comprising: The skin layers are laminated on both sides of the core layer, the resin forming the core layer is a polypropylene resin, the skin layer comprises an ethylene-propylene block copolymer and an ethylene-propylene random copolymer; the total content of the ethylene-propylene block copolymer, the ethylene-propylene random copolymer, and the polyethylene in the skin layer is 90% by mass or more; the ethylene content in the skin layer is 4.5% by mass or more and 40% by mass or less, The surface of the skin layer of the laminated film and a biaxially oriented polyester film are overlapped and measured, and the strength of the skin layer is 5.56 gf / cm 2 The static friction force A1 under pressure is 3.30 gf / cm 2 5.50 gf / cm or more 2 is as follows: The surface of the skin layer of the laminated film and a biaxially oriented polyester film are overlapped and measured, and the strength of the skin layer is 33.33 gf / cm 2 Static friction force A2 under pressure: 33.33 gf / cm 2 A laminated film in which the rate of change in the proportion of dynamic friction force B when pressure is applied: (1 + (dynamic friction force B - static friction force A2) ÷ static friction force A2) × 100 is 110% or more.

2. The laminate film of claim 1 , wherein the skin layer comprises polyethylene.

3. The laminated film according to claim 1 or 2, which is used to protect a pressure-sensitive adhesive layer.

4. A laminate comprising a substrate film, a pressure-sensitive adhesive layer, and the laminate film according to any one of claims 1 to 3 laminated in this order.

5. A roll of a laminate in which a base film, a pressure-sensitive adhesive layer, and the laminate film according to any one of claims 1 to 3 are laminated in this order, the pressure-sensitive adhesive layer is in contact with one surface of either the skin layer or the core layer of the laminated film, The laminate is wound around a core.

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