Contact roll, film winding device, and method for manufacturing film roll

Abstract

To provide a contact roll which enables sufficient reduction of its wrinkles or electrostatic charges of film rolls over a long time in manufacture of film rolls high in surface smoothness.SOLUTION: This contact roll comprises: a first layer composed of an elastic body on a core material; and a second layer which serves as an outermost layer outside the first layer. When a static friction coefficient on the surface of the second layer is μ0 and the thickness of the second layer is t μm, μ0 / t is 0.25 or lower.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a contact roll, a film winding device, and a method for manufacturing a film roll. [Background technology]

[0002] When a film, which is an electrically insulating sheet, is wound into a roll during its production process, it is important to ensure that defects in the roll shape, such as wrinkles, and defects in charging due to static electricity do not occur. Generally, when winding a film, a contact roll is pressed against the film roll to remove entrained air and improve the roll shape. In this case, the contact roll must remove air by following minute irregularities in the film roll caused by uneven thickness of the film, and therefore a rubber roll with a core made of rubber that is lower in hardness than a metal roll is often used. Contact rolls are also called contact pressure rolls, pressure rolls, nip rolls, or touch rolls.

[0003] Such contact rolls are required to have a low-friction surface in order to suppress wrinkles and static electricity buildup in the wound film roll. Generally, the coefficient of friction of the surface of a rubber roll decreases as the surface roughness increases, but the surface of a rubber roll gradually becomes flatter through repeated contact with the film, so the coefficient of friction gradually increases even for rubber rolls with high surface roughness. Therefore, in addition to a low-friction surface, contact rolls are also required to have good durability.

[0004] Under these circumstances, a method for forming a thin film made of diamond-like carbon (hereinafter abbreviated as DLC) on the rubber surface is available as a rubber roll that can maintain a lower coefficient of friction even after long-term use, and known methods include those disclosed in Patent Documents 1 to 3. A widely known method for forming a DLC film on a soft substrate such as rubber is the plasma CVD (chemical vapor deposition) method, and an example of this method is described in Patent Document 4. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-251373 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-81239 [Patent Document 3] WO2016-117634 publication [Patent Document 4] Japanese Patent Application Laid-Open No. 2002-121669 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in recent years, there has been a demand for films with smoother surfaces. For example, when winding highly smooth films with a surface roughness of 10 nm or less, it is difficult to obtain a film roll that sufficiently reduces wrinkles and electrostatic charging, even when using the contact rolls of Patent Documents 1 to 3. Therefore, the surface of the contact roll is required to have an even lower coefficient of friction and higher durability. Furthermore, problems with forming a DLC film on a soft substrate such as rubber, as in Patent Document 4, include the DLC film having high internal stress and low adhesion to the substrate, as well as the film cracking due to deformation of the substrate, making it prone to peeling. Therefore, the roll of Patent Document 4 has an issue with maintaining performance over a long period of time.

[0007] In view of the above-mentioned problems of the prior art, an object of the present invention is to provide a contact roll that can sufficiently reduce wrinkles and static electricity in a film roll over a long period of time, even in the production of a film roll with high surface smoothness. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention has the following configuration: A contact roll having a core material, a first layer made of an elastic body, and a second layer serving as an outermost layer outside the first layer, wherein when the static friction coefficient of the surface of the second layer is μ0 and the thickness of the second layer is t μm, μ0 / t is 0.25 or less. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a contact roll that can sufficiently reduce wrinkles and static electricity in a film roll over a long period of time, even in the production of a film roll with high surface smoothness. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing the configuration of a DLC film forming apparatus for obtaining a contact roll according to one embodiment of the present invention. [Figure 2] 1 is a schematic cross-sectional view of a contact roll according to one embodiment of the present invention. [Figure 3] 1 is a schematic cross-sectional view of a winding device using a contact roll according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The contact roll of the present invention will be specifically described below. The contact roll of the present invention is a contact roll comprising a core material, a first layer made of an elastic body, and a second layer serving as an outermost layer outside the first layer, characterized in that, when the static friction coefficient of the surface of the second layer is μ0 and the thickness of the second layer is t μm, μ0 / t is 0.25 or less.

[0012] In the present invention, the term "core material" refers to a roughly cylindrical material located inside the first layer made of an elastic body. Metals such as iron, SUS, and aluminum, as well as fiber-reinforced plastics (FRP) using carbon fiber as a reinforcing member, are preferably used as materials for the core material. The core material may be hollow or solid. Here, "roughly cylindrical" refers to a shape that has a cylindrical overall shape or a roughly cylindrical shape when observed macroscopically, and includes a shape in which the diameter varies slightly depending on the axial location. Specifically, this includes a true cylindrical shape, a crown shape in which the diameter at the axial center is larger than at both ends, and an inverted crown shape in which the diameter at the axial center is smaller than at both ends.

[0013] In the present invention, "comprised of an elastomer" means that 80% by mass to 100% by mass, preferably 80% by mass to 99.9% by mass, of all components constituting the first layer are elastomers. The "elastomer" preferably includes one or more of chloroprene rubber, ethylene propylene rubber, silicone rubber, urethane rubber, acrylonitrile butadiene rubber, styrene butadiene rubber, butyl rubber, chlorosulfonated polyethylene rubber, and fluororubber. It is also preferable that the rubber used has an appropriate hardness, as described below. The surface of this layer also preferably has a roughly cylindrical shape, and, like the "core material," a crown shape, an inverted crown shape, or the like may be used depending on the purpose. These elastomers may be used alone or in combination.

[0014] The first layer may contain 0.1% by mass or more and 20% by mass or less of components other than rubber, such as a filler. The filler material is not particularly limited, and examples of fillers that improve the physical properties of elastomers (such as vulcanized rubber) include carbon black, silica, alumina, calcium carbonate, talc, and clay, which can be used alone or in combination. A filler content of 0.1% by mass or more can be expected to provide a sufficient reinforcing effect. Meanwhile, the advantages of a filler content of 20% by mass or less include sufficient flexibility of the elastomer substrate, reduced increase in roll surface hardness, and reduced cracking in the first layer.

[0015] The hardness of the first layer is preferably 70° or less in order to conform to minute irregularities in the film roll resulting from uneven thickness of the film being produced and remove air. Having a hardness of 70° or less allows the contact roll surface to conform to uneven thickness of the film, reducing fluctuations in the contact pressure state. Meanwhile, from the viewpoint of rubber moldability, the lower limit of the hardness of the first layer is desirably 30° or more. Therefore, from the viewpoint of rubber moldability and conformability to minute irregularities in the film roll, the hardness of the first layer is desirably in the range of 30° or more to 70° or less.

[0016] The surface of the first layer may be surface treated by physical means such as polishing, chemical means using chemical solutions, optical means using ultraviolet rays or the like, or electrical means using discharge or plasma or the like.

[0017] It is important that the contact roll of the present invention has a second layer, which serves as the outermost layer, outside the first layer. Even if the surface of the first layer is subjected to the above-mentioned surface treatment, it gradually becomes flattened by repeated contact with the film, making it impossible to maintain a low static friction coefficient for a long period of time. To solve this problem, it is important to have a second layer with excellent wear resistance.

[0018] In the contact roll of the present invention, the static friction coefficient μ0 of the surface of the second layer is preferably 0.10 or more and 0.20 or less. Having a static friction coefficient μ0 of 0.10 or more on the surface of the second layer prevents the film from slipping through at the contact pressure area between the contact roll and the film roll, reducing the occurrence of wrinkles due to tight winding. On the other hand, having a static friction coefficient μ0 of 0.20 or less on the surface of the second layer not only suppresses frictional charging at the contact pressure area to a sufficient level, but also reduces the occurrence of wrinkles. The effect of having a static friction coefficient μ0 of 0.10 or more and 0.20 or less on the surface of the second layer is particularly evident when winding a highly smooth film with a surface roughness of 10 nm or less.

[0019] The static friction coefficient μ of the surface of the second layer is the value when rubbed against a polyethylene terephthalate film "Lumirror" (registered trademark) manufactured by Toray Industries, Inc., which has a thickness of 6.3 μm and a surface roughness of 20 nm, and can be measured by the Heidon friction measurement method. Detailed measurement conditions are shown in the examples.

[0020] One way to achieve a static friction coefficient μ0 of the second layer surface between 0.10 and 0.20 is to use a silicon-containing DLC layer as the B layer. More specifically, μ0 can be reduced by increasing the silicon content; methods for depositing silicon-containing DLC are described below. Another method is to form the second layer on a roughened first layer. Roughening the surface of the first layer reduces the contact area, thereby reducing μ0. Surface treatment methods include physical methods such as polishing, chemical methods using chemicals, optical methods using ultraviolet light, and electrical methods using discharge or plasma.

[0021] In the contact roll of the present invention, the thickness t of the second layer is preferably 1.0 μm or less from the viewpoint of reducing scratches and wrinkles on the film. By keeping t at 1.0 μm or less, the occurrence of cracks on the outermost surface of the contact roll caused by internal stress resulting from the difference in elastic modulus between the first layer and the second layer, which are made of different materials, is reduced. As a result, scratches and wrinkles on the film originating from cracks can be reduced. The lower limit of the thickness t of the second layer and the method for measuring it will be described later.

[0022] When using a plasma CVD method, the thickness t of the second layer can be controlled within the above range by adjusting the source gas species, source gas flow rate, discharge plasma generation power, frequency, discharge time, and the like, and can be controlled by optimizing them according to the target thickness.

[0023] In the contact roll of the present invention, it is important that the second layer is made of diamond-like carbon (DLC). In the present invention, "the second layer is made of DLC" refers to a state in which the second layer has an amorphous crystalline structure with both diamond and graphite bonds, and 60 at% to 99 at% of the total components of the second layer is carbon, with a portion of the crystalline structure being substituted with other elements. DLC consisting of 60 at% or more of carbon provides the DLC film with sufficient hardness, reducing wear due to repeated use, and enabling longer use as a contact roll. Of the components other than carbon, which are 1 at% to 40 at% inclusive, 1 at% to 18 at% inclusive is preferably silicon. Other elements, such as hydrogen, oxygen, and fluorine, may also be present as long as they do not significantly impair surface properties or wear resistance.

[0024] The DLC film of the present invention can be formed, for example, by plasma CVD using hydrocarbon gases such as methane, acetylene, or ethylene. Because this method uses hydrocarbon gases as precursor materials, it inevitably results in a DLC film containing hydrogen. Other methods, such as sputtering, ion beam deposition, and ion plating, can also be used. These methods use solid targets such as graphite as precursor materials, which are vaporized by plasma, resulting in a DLC film that does not contain hydrogen. The presence of hydrogen in a DLC film has the advantages of reducing internal stress within the film, allowing for thicker films, and making the film more flexible, improving its ability to follow elastic deformation. However, the disadvantage is that the increased flexibility reduces wear resistance.

[0025] Hereinafter, a roll having only the first layer coated on a core material will be referred to as an elastic roll. The plasma CVD method will be described with reference to Figure 1. Figure 1 is a schematic diagram of a DLC film deposition apparatus for obtaining a contact roll according to one embodiment of the present invention. In Figure 1, a vacuum chamber 1 is depressurized by a vacuum pumping mechanism 2. An elastic roll 3 to be surface-treated is set inside the vacuum chamber 1 along with a rotation drive means 4. Power is supplied from a power source 6 to a plasma generation electrode 5. Argon gas is supplied through a gas inlet tube 7 to clean the surface of the elastic roll 3, and then a hydrocarbon gas such as methane or acetylene is supplied to generate plasma. When silicon is added, a silicon-based gas such as tetramethylsilane or tetraethoxysilane is simultaneously supplied to generate plasma. Multiple individual gas inlet tubes 7 may be used to simultaneously introduce multiple gases (however, Figure 1 shows only one). The silicon content can be controlled by adjusting the flow rate ratio of the hydrocarbon gas and the silicon-based gas. The hydrogen content can be adjusted by selecting a hydrocarbon gas with a different carbon-to-hydrogen ratio depending on the required content, and can be controlled by the flow rate ratio with other gases. A DLC film of a predetermined thickness is formed on the surface of the elastic roll while the roll is rotated at a speed of 1 to 10 rpm. The core material of the elastic roll is electrically grounded, and AC power from a power source 6 generates plasma between the first layer and the plasma generating electrode 5. However, a counter electrode separate from the elastic roll may be provided, or plasma can be generated using DC power. It is not necessary to rotate the elastic roll continuously during DLC film formation; for example, the film can be formed in several separate steps around the circumference of the elastic roll.

[0026] In the contact roll of the present invention, the second layer preferably has an A layer in contact with the first layer and a B layer serving as the outermost layer, and more preferably the B layer is made of DLC containing silicon. The A layer in contact with the first layer will be described later. Here, "DLC containing silicon" refers to DLC that has an amorphous structure with both diamond and graphite bonds, contains 60 at% to 99 at% of all components as carbon, and contains 1.2 at% to 20 at% of silicon. "Layer B is made of DLC containing silicon" means that Layer B has the above amorphous structure and satisfies the above elemental composition.

[0027] DLC containing silicon is generally known to exhibit a very low coefficient of friction. This is thought to be due to the silicon-oxygen compound formed when silicon in the film reacts with moisture in the atmosphere during sliding, acting as a low-friction agent. A silicon content of 1.2 at% or more in Layer B facilitates achieving a static friction coefficient of 0.2 or less on the contact roll surface. A silicon content of 20 at% or less ensures sufficient static friction coefficient and reduces cracking and peeling from Layer A due to embrittlement. The relationship between silicon content and static friction coefficient shows a steep change in the range below 5 at%, with slight differences in content resulting in fluctuations in the static friction coefficient. Therefore, to achieve a stable static friction coefficient, it is preferable to set the silicon content of Layer B to 5 at% or more and 20 at% or less. Note that Layer B may contain hydrogen, oxygen, fluorine, etc., in a range of 0.1 at% to 38.8 at%.

[0028] Next, the A layer in the contact roll of the present invention will be described. The higher the silicon content of silicon-containing DLC, the more difficult it becomes to adhere it to the elastic roll. Therefore, it is preferable to provide an A layer between the first layer and the B layer, which has good adhesive compatibility with both. From the above perspective, the A layer is preferably a DLC layer with a lower silicon content than the B layer, and more preferably a DLC layer without silicon. Furthermore, due to the brittle nature of silicon, providing an A layer is also effective from the perspective of supplementing the durability of the B layer with an underlying layer. Like the B layer, the A layer may contain elements such as hydrogen, oxygen, and fluorine in an amount of 0.1 at% to 39 at% of the total components.

[0029] The lower limit of the thickness t of the second layer in the present invention will be explained. When forming a film to a predetermined thickness, where tA is the thickness of layer A and tB is the thickness of layer B, if tB is 0.1 μm or more, the film will exhibit lower static friction characteristics than a DLC layer that does not contain silicon, and will be sufficiently effective against wrinkles and electrostatic charging. Furthermore, it is difficult to control tB to a thickness of less than 0.1 μm with current film formation technology. Similarly, tA must be 0.1 μm or more from the perspective of improving adhesion with layer B, and t(tA + tB) is preferably 0.2 μm or more and 1.0 μm or less.

[0030] In the contact roll of the present invention, it is important that μ0 / t is 0.25 or less, where μ0 is the static friction coefficient of the surface of the second layer and t μm is the thickness of the second layer. In this invention, "μ0 / t" represents the static friction coefficient per thickness. Generally, the thicker the second layer, the rougher the surface becomes, so that when the contact roll and the film roll come into contact, the surface protrusions come into contact preferentially, reducing friction. Therefore, μ0 / t can be said to be a parameter that eliminates the effect of increased surface roughness due to a thicker second layer and allows comparison of the main effect of the DLC film composition at each thickness range.

[0031] In the present invention, μ0 / t is preferably 0.10 or more and 0.25 or less. By setting μ0 / t to 0.10 or more, slippage of the film at the contact pressure portion between the contact roll and the film roll is reduced, and the occurrence of wrinkles due to tight winding is suppressed. On the other hand, if μ0 / t exceeds 0.25, it is difficult to obtain a film roll free of wrinkles and static electricity when winding a highly smooth film, for example, one with a surface roughness of 10 nm or less.

[0032] In order to control μ0 / t to 0.25 or less, it is effective to appropriately combine the above-mentioned methods of adjusting μ0 and t, for example.

[0033] μ0 / t also depends on the surface roughness of the elastic roll that serves as the base material. When used as a contact roll for winding a film roll, if the surface is too rough, contact pressure will be concentrated on the surface protrusions of the contact roll, which will likely cause minute deformations in the film roll starting from the protrusions. In the present invention, the appropriate range for the surface roughness of the contact roll (second layer) is 0.1 μm or more and 1.4 μm or less. Note that it is technically difficult to polish the surface of the relatively soft first layer to less than 0.1 μm.

[0034] From the viewpoint of eliminating entrained air during film winding and improving the winding appearance, the contact roll of the present invention has an advantage in that a smaller diameter reduces the contact area with the film, thereby enabling a relatively higher pressure to be applied to the film roll. On the other hand, when using a contact roll with a small diameter, the smaller the diameter, the higher the roll rotation speed and the greater the number of times it comes into contact with the film roll. Naturally, the greater the number of times it comes into contact, the more easily the contact roll wears. In other words, the smaller the diameter of the contact roll, the greater the effect of forming the DLC film of the present invention, and this is preferable. However, if the diameter of the contact roll is too small, its durability will be weakened and it will be difficult to apply sufficient force, so it is preferable to select a contact roll with an appropriate diameter depending on the purpose. From the above viewpoint, the diameter of the contact roll is preferably in the range of 25 mm to 300 mm, but a diameter of 120 mm or less will be particularly effective in increasing the number of times it comes into contact with the film roll, thereby increasing the advantages of using the contact roll of the present invention.

[0035] A specific example of the contact roll of the present invention will be described below with reference to Fig. 2, which is a schematic cross-sectional view of a contact roll according to one embodiment of the present invention. In Fig. 2, a contact roll 8 has a first layer 10 made of an elastic material formed on the surface of a core material 9, an A layer 11 made of DLC in contact with the outside of the first layer 10, and a B layer 12 made of DLC containing silicon as the outermost layer. The A layer 11 and B layer 12 together constitute the second layer.

[0036] The film winding device of the present invention will be described below. The film winding device of the present invention is characterized by including the contact roll of the present invention. A more specific description will be given below with reference to Figure 3, which is a schematic cross-sectional view of a winding device using a contact roll according to one embodiment of the present invention.

[0037] The winding device shown in FIG. 3 has a film transport means for continuously transporting film F in a predetermined direction. Part of this film transport means is a rotatable transport roll 13. The running direction of film F is indicated by arrow FD. Film F travels in the direction of arrow FD while supported by transport roll 13 and other components. A winding core 14 is rotated by a driving means (not shown) to wind film F and form a film roll 15. The contact roll 8 described in FIG. 2 is rotatably supported as a contact pressure roll and is connected to a hydraulic cylinder (not shown). The hydraulic cylinder biases the contact roll 8 toward film roll 15, pressing it against the film roll 15. In the winding device shown in FIG. 3, a static eliminator is disposed across the entire width of the film roll, facing the contact area between the contact roll 8 and film roll 15. The static eliminator has a corona discharge electrode 16 and a shield electrode 17. The corona discharge electrode 16 is connected to a DC or AC high-voltage power supply 18. The static eliminator generates positive and negative ions by applying a high voltage to the corona discharge electrode 16, and supplies the ions to the film roll 15 to eliminate the charge on the film roll 15. If the static elimination distance is greater than 100 mm, the ions may be sprayed, an air nozzle (not shown) may be installed near the corona discharge electrode 16, or one integrated with the electrode may be used.

[0038] Next, a method for producing a film roll of the present invention will be described. The method for producing a film roll of the present invention includes a step of winding a film using the film winding device of the present invention. The film referred to here is not particularly limited, but from the viewpoint of the great advantages of using the winding device of the present invention, a film having a surface roughness of 10 nm or less is preferred. The film will be described below.

[0039] The term "film" refers to a sheet-like molded product made of a thermoplastic resin or a thermoplastic resin as its main component (a component contained in an amount of more than 50% by mass and not more than 100% by mass). Among these, plastic films such as polyethylene terephthalate film, polyethylene naphthalate film, polypropylene film, polystyrene film, polycarbonate film, polyimide film, polyphenylene sulfide film, nylon film, aramid film, and polyethylene film have high insulating properties and are suitable for use in the film roll manufacturing method of the present invention from the viewpoint of suppressing charging defects.

[0040] A "film with a surface roughness of 10 nm or less" refers to a film having a surface roughness within this range on at least one side of the film. The film may have multiple layers in the thickness direction, and particles may be contained in the outermost layer of the film. The type of particles is not particularly limited, and may be inorganic particles, organic particles, or a mixture thereof, and known particles can be used. For example, inert inorganic particles selected from alumina, zirconia, silica, titanium oxide, calcium carbonate particles, etc., or organic particles such as polystyrene and divinylbenzene particles can be used.

[0041] Methods for controlling the surface roughness of a film to 10 nm or less include, for example, adjusting the particle size or content of particles contained in the layer located on the outermost surface of the film. Furthermore, a film surface roughness of 1 nm or more prevents deterioration of the slipperiness between the transport roll and the transport film, reducing the occurrence of scratches, wrinkles, and the like, thereby enabling the production of a film with stable quality. From the above perspectives, the surface roughness of the film is preferably 1 nm or more and 10 nm or less on at least one side.

[0042] The method for producing a film roll of the present invention will be described below using a polyethylene terephthalate (PET) film roll having a surface roughness of 10 nm or less as a representative example, but the method for producing a film roll of the present invention is not particularly limited to this.

[0043] First, pellets containing particles in PET are prepared. One method for obtaining particle-containing PET pellets is to disperse particles in a predetermined ratio in ethylene glycol, a diol component, in the form of a slurry, and then add this ethylene glycol slurry at any stage before the completion of PET polymerization. Furthermore, in order to improve the dispersibility of particles in particle-containing PET pellets, it is effective to reduce the particle concentration in the pellets.

[0044] The particle-containing PET pellets and the particle-free PET pellets prepared as described above are mixed in a predetermined ratio, dried, and then fed to a known melt lamination extruder, and the polymer is filtered through a filter. To prevent re-agglomeration of particles during filtration, it is effective to use a high-precision sintered stainless steel filter capable of capturing at least 95% of foreign matter 1.5 μm or larger in size.

[0045] The molten PET composition is then extruded through a slit-shaped die into a sheet and cooled and solidified on a casting roll to form an unstretched film. To form a laminated structure, the required number of layers are laminated using multiple extruders, multiple manifolds, or merging blocks (e.g., a merging block having a rectangular merging portion), and the sheet is extruded through the die and cooled on a casting roll to obtain an unstretched film. In this case, it is effective to install a static mixer or gear pump in the polymer flow path from the viewpoint of stabilizing back pressure and suppressing thickness fluctuations.

[0046] The unstretched film is then stretched biaxially in the longitudinal and transverse directions, followed by heat treatment. The stretching process may be simultaneous biaxial stretching or sequential biaxial stretching. Simultaneous biaxial stretching does not involve stretching with rolls, so localized heating of the film surface does not occur, making it easier to control surface properties, and is therefore more preferred as a stretching method.

[0047] In simultaneous biaxial stretching, both widthwise ends of an unstretched film are gripped with clips on each side of a tenter apparatus, and the unstretched film is preheated by applying heat. The film is then simultaneously stretched in the longitudinal and width directions at a stretching temperature of, for example, 80 to 160°C. A stretching temperature of 80°C or higher is preferred in that film breakage can be suppressed, while a stretching temperature of 160°C or lower is preferred in that sufficient strength can be obtained. Furthermore, from the viewpoint of reducing stretching unevenness, the total stretch ratio (area stretch ratio) in the longitudinal and width directions is preferably, for example, 8 to 30 times. An area stretch ratio of 8 times or higher is preferred in that sufficient strength can be obtained, and an area stretch ratio of 30 times or lower is preferred in that film breakage during the production process can be suppressed.

[0048] The film is then heat-set at, for example, 180 to 235°C for, for example, 0.5 to 20 seconds. A heat-set temperature of 180°C or higher promotes crystallization of the film, stabilizing its structure. Furthermore, a heat-set temperature of 235°C or lower can suppress a decrease in Young's modulus due to the progress of relaxation of the polyester amorphous chain portion, thereby achieving sufficient strength. Subsequently, during slow cooling after the heat treatment, a relaxation treatment of, for example, 0.5 to 7.0% may be performed in the longitudinal and / or transverse directions.

[0049] The case of sequential biaxial stretching will be explained. First, longitudinal stretching is usually performed by the difference in peripheral speed of rolls, and this stretching may be performed in one stage or in multiple stages using multiple pairs of rolls. The stretching ratio is preferably 2 to 7 times, and the stretching temperature is preferably 80 to 160°C.

[0050] Next, the film is conveyed while being held at both widthwise ends with clips of a tenter device, and after preheating by applying heat, it is stretched in the widthwise direction. The stretching ratio is preferably 2 to 7 times, and the stretching temperature is preferably 80 to 160°C. The subsequent process from heat setting to slow cooling is the same as for simultaneous biaxial stretching.

[0051] The polyester film thus obtained passes through a transport roll and is then supplied to a winder equipped with a winding device, such as that shown in Figure 3. Before being supplied to the winding device, both widthwise ends of the film may be trimmed using a trimming device. The thickness of the transported film can be measured using a non-contact online thickness gauge capable of scanning in the widthwise direction, and can be adjusted by controlling the amount of polymer discharged from the spinneret. The film F thus supplied is wound around a gripped winding core 14, yielding a film roll 15 as an intermediate product.

[0052] Thereafter, the intermediate product is unwound by a slitter as needed, passed through a conveying roll, slit to a predetermined width using a cutter, and fed to the winding device shown in Figure 3, where the slit film is wound around a winding core 14 to obtain a film roll 15 as a finished product. In this case, one intermediate product may produce one or more finished products. The contact roll of the present invention is preferably used as the contact roll of a winder or a slitter in such a film production process.

[0053] The nip roll may also be used as a nip roll to suppress slippage between the film and the transport roll when stretching in the longitudinal direction by utilizing the difference in peripheral speed of the rolls. The nip roll is a roll for nipping and pressing the film on the transport roll. [Example]

[0054] The present invention will be described in more detail below using examples, but the present invention is not limited to the following embodiments. Not determined. It should be noted that Example 4 should be read as Reference Example 4.

[0055] [Methods for evaluating physical properties and effects] (Static friction coefficient of contact roll) The static friction coefficient was measured using the Heidon friction measurement method. A 6.3 μm thick, 20 nm surface roughness polyethylene terephthalate film (Lumirror®) manufactured by Toray Industries, Inc. was used as the friction target. A Heidon Tribogear Type 94i static friction coefficient measurement device was used. The polyethylene terephthalate film was attached to the measuring slider of the measuring device, and the measuring device was pressed against the surface of a roll placed stationary with its axial direction horizontal. The static friction coefficient was determined by fixing the roll at an arbitrary position in the circumferential direction, dividing the width direction into six equal parts, and measuring at five points on the equal divisions excluding the very edge of the roll, and averaging the values obtained.

[0056] (film surface roughness) A film sampled from an arbitrary position on the film roll was cut into a 7 cm square, and the surface roughness of one side of the obtained sample was measured and calculated using a 3D roughness meter "VertScan" (registered trademark) 2.0 manufactured by Ryoka Systems Co., Ltd. Specifically, the objective lens was 50x, the internal lens was 0.5x, the measurement mode was Wave mode, and the measurement area was 0.0497 mm 2 The surface roughness (unit: nm) was measured in an arbitrary area on the surface of the measurement sample. Using the same sample, measurements were repeated 90 times on the same surface, with the measurement area arbitrarily changed, and the average surface roughness was calculated, and the obtained value was taken as the surface roughness of that surface. The surface roughness of the opposite surface was measured and calculated in the same way.

[0057] (Surface roughness of contact roll) A Keyence VK8500 ultra-deep profile measuring microscope was used. The contact roll was fixed to the stage of the microscope, and its surface profile was captured as image data at a magnification of 2000x and a vertical resolution of 0.05 μm. Next, a measurement line was drawn horizontally from the left edge to the right edge of the image, and the line roughness between the two points was read as the surface roughness. The laser and camera shutter were set to automatic mode. The surface roughness of the contact roll was determined by fixing the roll at an arbitrary position in the circumferential direction, dividing the width direction into six equal parts, and observing and measuring five points on the equal dividing lines excluding the very edge of the roll, and averaging the values obtained.

[0058] (Hardness of contact roll) The measurement was carried out according to the method specified in JIS K 6253 (2012) Type A. Specifically, the JIS spring type hardness tester specified in this standard was placed horizontally on a roll that was placed stationary with its axial direction horizontal, and the hardness reading was read when a load of 9.8 N was applied. The hardness of the contact roll was determined by fixing the position in the circumferential direction at an arbitrary position, dividing the width direction into six equal parts, and measuring at five equal points on the dividing lines excluding the very edge of the roll, and calculating the average value of the values obtained.

[0059] (Method for evaluating DLC film thickness) Two masked Si substrates were placed adjacent to the roll used for the film formation process. After the 2-A layer was formed, one of the two Si substrates was removed and the difference in height between the masked and unmasked portions was measured to determine the thickness tA. Subsequently, after the 2-B layer was formed, the remaining Si substrate was removed and the difference in height between the masked and unmasked portions was measured to determine the thickness t. tB was calculated from the difference between t and tA. The difference in height was observed and measured using a scanning electron microscope (SEM) according to the following procedure. First, a cross section including the Si substrate cut perpendicular to the unmasked surface where the second layer was formed in the unmasked portion was imaged using an SEM (S-3400N scanning electron microscope, Hitachi High-Technologies Corporation) with a LaB6 source and an accelerating voltage of 15 kV at 20,000x magnification. The vertical distance from the interface between the first and second layers to the surface of the second layer was measured at any five points in the image, and the average of these measurements was used to determine the thickness.

[0060] (Evaluation of wound film rolls) ·Whether wrinkles occur The film was unwound from the film roll obtained using a winding device equipped with the winding section shown in Figure 3, and the film was checked for wrinkles under free tension (a state in which the film was hanging vertically under its own weight) and a load of 3 kg / m. The presence or absence of wrinkles was checked by illuminating the film with 750 Lux lighting and visually inspecting the entire length equivalent to five revolutions of the film roll, and the wrinkle evaluation was based on the following criteria. ◎: No wrinkles with free tension. Good: Wrinkles were present under free tension, but the wrinkles disappeared under a tension of 3 kg / m. ×: Wrinkles were present under free tension, and the wrinkles did not disappear even under a tension of 3 kg / m.

[0061] -Whether or not charging defects occur First, a film roll obtained using a winding device equipped with the winding section shown in Figure 3 was unwound one full rotation of the film and cut parallel to the width direction. Next, a general-purpose black toner liquid was sprayed all over the cut film to visualize the charged areas. Charged and uncharged areas can be distinguished by the presence or absence of toner adhesion, and all observations were made visually. Charging defects were judged using the following method. ◯: No toner was attached to the entire surface of the film. x: Toner adhesion was observed in localized areas of the film.

[0062] (Long term durability) Only in Example 1 and Comparative Examples 3 and 4 described later, the surface roughness of the contact roll and the wound-up film roll were similarly evaluated after the contact roll was used for one month.

[0063] [Contact Role] The contact rolls and the manufacturing methods thereof in the examples and comparative examples will be described with reference to the drawings.

[0064] (Contact Roll A: Used in Example 1) A contact roll having a face length (widthwise length) of 1.1 m and a diameter of 120 mm, as shown in FIG. 2, was fabricated. The core material 9 of the contact roll 8 was an iron core, and the first layer 10 was made of chloroprene rubber with a hardness of 40°. The surface of the roll, with the core material 9 and the first layer 10 formed thereon, was polished with a product called "Exsaine" (registered trademark) (manufactured by Toray Industries, Inc.), and then treated with a chemical containing a halogen. Subsequently, a DLC film (2-A layer 11) having a thickness tA of 0.7 μm and containing 70 at% carbon and 30 at% hydrogen was formed using a hydrocarbon gas as described in Patent Document 4 by the plasma CVD method shown in FIG. 1. Next, a DLC film (2-B layer 12) having a thickness tB of 74 at% carbon, 20 at% hydrogen, and 6 at% silicon was formed using a hydrocarbon gas and a silicon gas in the same manner as for the 2-A layer 11, to form a contact roll A. The surface roughness of the contact roll A was 1.1 μm, and the static friction coefficient μ0 was 0.11.

[0065] (Contact Roll B: Used in Example 2) A contact roll was fabricated in the same manner as contact roll A, except that the first layer 10 was a mixture of 95% by mass of acrylonitrile butadiene rubber with a hardness of 60° and 5% by mass of conductive carbon black, the thickness tA of the 2-A layer 11 was 0.3 μm, and the thickness tB of the 2-B layer 12 was a DLC film containing 70 at% carbon, 10 at% hydrogen, and 20 at% silicon. This contact roll was designated contact roll B. The surface roughness of contact roll B was 0.65 μm, and μ0 was 0.12. The composition of the 2-B layer was determined by using methane and tetramethylsilane as source gases and appropriately adjusting the gas flow rate ratio to achieve the desired composition. The same applies below.

[0066] (Contact Roll C: Used in Example 3) A contact roll was produced in the same manner as contact roll A except that the component composition of 2-B layer 12 was changed to 70 at % carbon, 27 at % hydrogen, and 3 at % silicon, and this contact roll was named contact roll C. The surface roughness of contact roll C was 0.65 μm, and μ0 was 0.20.

[0067] (Contact Roll D: Used in Example 4) A contact roll was produced in the same manner as contact roll B except that the surface of the first layer 10 was blasted, tA was set to 1.0 μm, and the 2-B layer 12 was not formed, and this contact roll was designated contact roll D. The surface roughness of contact roll D was 2.0 μm, and μ0 was 0.25.

[0068] (Contact Roll E: Used in Example 5) The surface of the first layer 10 was blasted, and a contact roll was produced in the same manner as for the contact roll B, and this was designated as contact roll E. The surface roughness of contact roll E was 1.4 μm, and μ0 was 0.09.

[0069] (Contact Roll F: Used in Comparative Example 1) A contact roll was produced in the same manner as contact roll A except that tA was set to 1.0 μm and tB was set to 0.5 μm, and this was designated contact roll F. Contact roll F had cracks that were visible across the entire surface, and it was therefore impossible to evaluate the surface roughness and μ0.

[0070] (Contact Roll G: Used in Comparative Example 2) A contact roll was produced in the same manner as contact roll A, except that the 2-A layer 11 was not formed and the 2-B layer 12 was formed on the outside of the first layer 10 so as to have a thickness tB of 1.0 μm, and this contact roll was designated contact roll G. Contact roll G had cracks that were visible over the entire surface, and evaluation of the surface roughness and μ0 was not possible.

[0071] (Contact Roll H: Used in Comparative Example 3) A contact roll was produced in the same manner as contact roll A except that tA was set to 1.0 μm and the 2-B layer 12 was not formed, and this contact roll was designated contact roll H. The surface roughness of contact roll H was 1.1 μm, and μ0 was 0.28.

[0072] (Contact Roll I: Used in Comparative Example 4) A contact roll was produced in the same manner as contact roll A, except that the surface of the first layer 10 was polished with a product under the trade name "Ecsaine" (registered trademark) (manufactured by Toray Industries, Inc.) and subjected to ultraviolet treatment, and the second layer (2-A layer 11, 2-B layer 12) was not formed, and this contact roll was designated contact roll I. The surface roughness of contact roll I was 0.9 μm, and μ0 was 0.80.

[0073] [Raw materials] The following raw materials were used to manufacture the film rolls in each of the Examples and Comparative Examples.

[0074] (Polyethylene terephthalate) 194 parts by mass of dimethyl terephthalate and 124 parts by mass of ethylene glycol were charged into an ester exchange reactor, and the contents were heated to 140°C to dissolve. Thereafter, 0.3 parts by mass of magnesium acetate tetrahydrate and 0.05 parts by mass of antimony trioxide were added while stirring the contents, and an ester exchange reaction was carried out while distilling off methanol at 140 to 230°C. Next, 0.5 parts by mass of a 5% by mass ethylene glycol solution of trimethyl phosphate (0.025 parts by mass as trimethyl phosphate) and 0.3 parts by mass of a 5% by mass ethylene glycol solution of sodium dihydrogen phosphate dihydrate (0.015 parts by mass as sodium dihydrogen phosphate dihydrate) were added.

[0075] When the trimethyl phosphate ethylene glycol solution was added, the temperature of the reaction contents dropped. Therefore, the excess ethylene glycol was distilled off while stirring was continued until the temperature of the reaction contents returned to 230°C. After the temperature of the reaction contents in the transesterification reactor reached 230°C in this way, the reaction contents were transferred to the polymerization reactor.

[0076] After the transition, the temperature of the reaction system was gradually increased from 230°C to 290°C, and the pressure was reduced to 0.1 kPa. The time to reach the final temperature and the final pressure was both 60 minutes. After reaching the final temperature and final pressure, the reaction was continued for 2 hours (3 hours from the start of polymerization), at which point the stirring torque of the polymerization apparatus reached a predetermined value (the specific value varies depending on the specifications of the polymerization apparatus, but the value indicated by polyethylene terephthalate with an intrinsic viscosity of 0.62 in this polymerization apparatus was used as the predetermined value). The reaction system was then purged with nitrogen and returned to normal pressure to stop the polycondensation reaction, and the mixture was discharged into cold water in the form of strands, which were immediately cut to obtain pellets of polyethylene terephthalate with an intrinsic viscosity of 0.62.

[0077] (Thermoplastic resin A) Polyethylene terephthalate pellets containing 0.52% by mass of spherical silica particles with an average particle size of 0.10 μm (hereinafter sometimes referred to as master pellets 1), the above polyethylene terephthalate pellets containing essentially no particles, and a heat-resistant thermoplastic resin, "Ultem" (registered trademark) 1010 manufactured by SABIC Innovative Plastics (hereinafter sometimes simply referred to as heat-resistant thermoplastic resin), were mixed so that the contents of the spherical silica particles and the heat-resistant thermoplastic resin were 0.05% and 4% by mass, respectively, to prepare thermoplastic resin A. Master pellets 1 were produced by feeding 95 parts by mass of the above polyethylene terephthalate pellets and 5 parts by mass of a 10% by mass aqueous slurry of spherical silica particles with an average particle size of 0.10 μm (0.5 parts by mass as spherical silica particles) into a vented twin-screw extruder heated to 280°C, and then maintaining a reduced pressure of 1 kPa or less through the vent hole to remove water.

[0078] (Thermoplastic resin B) Thermoplastic resin B was obtained by mixing polyethylene terephthalate pellets containing 2.44 mass% of cross-linked polystyrene particles having an average particle size of 0.30 μm (hereinafter sometimes referred to as master pellets 2), polyethylene terephthalate containing 0.11 mass% of cross-linked polystyrene particles having an average particle size of 0.80 μm (hereinafter sometimes referred to as master pellets 3), the above polyethylene terephthalate pellets containing essentially no particles, and a heat-resistant thermoplastic resin, "Ultem" (registered trademark) 1010 manufactured by SABIC Innovative Plastics (hereinafter sometimes simply referred to as heat-resistant thermoplastic resin), so that the contents of the cross-linked polystyrene particles having an average particle size of 0.30 μm, the cross-linked polystyrene particles having an average particle size of 0.80 μm, and the heat-resistant thermoplastic resin were 0.26 mass%, 0.01 mass%, and 4 mass%, respectively. Master pellets 2 were produced by feeding 80 parts by mass of the polyethylene terephthalate pellets and 20 parts by mass of a 10% by mass aqueous slurry of cross-linked polystyrene particles having an average particle size of 0.30 μm (2 parts by mass as cross-linked polystyrene particles) into a vented twin-screw extruder heated to 280°C, and removing water while maintaining a reduced pressure of 1 kPa or less through the vent hole. Master pellets 3 were produced by feeding 95 parts by mass of the polyethylene terephthalate pellets and 5 parts by mass of a 2% by mass aqueous slurry of cross-linked polystyrene particles having an average particle size of 0.80 μm (0.1 part by mass as cross-linked polystyrene particles) into a vented twin-screw extruder heated to 280°C, and removing water while maintaining a reduced pressure of 1 kPa or less through the vent hole.

[0079] [Take-up device] The winding device used is shown in Figure 3. It will be explained in detail below. The winding device has a film transport means for continuously running film F in the direction indicated by the symbol FD, part of which is a rotatable transport roll 13. A winding core 14 is rotated by a driving means (not shown) to wind film F and form a film roll 15. A rotatable contact roll 8 connected to a hydraulic cylinder (not shown) is biased toward film roll 15 by the action of the hydraulic cylinder, bringing it into contact with film roll 15. Furthermore, a static eliminator is disposed across the entire width of the film roll toward the contact point between contact roll 8 and film roll 15. The static eliminator has a corona discharge electrode 16 and a shield electrode 17, and the corona discharge electrode 16 is connected to a DC or AC high-voltage power supply 18.

[0080] [Example 1] Thermoplastic resin A (A layer raw material) and thermoplastic resin B (B layer raw material) were dried under reduced pressure at 160°C for 8 hours, then fed into separate extruders, melt-extruded at 275°C, filtered through a fiber-sintered stainless steel filter (filtration accuracy 1.4μm) and a powder-sintered stainless steel filter (filtration accuracy 20μm), and laminated in a rectangular two-layer merging block so that the lamination thickness ratio (A layer / B layer) was 7 / 1. The resulting molten laminate was then formed into a sheet using a die maintained at 295°C and extruded. Using an electrostatic casting method, the B layer side was wrapped around a casting drum at a surface temperature of 25°C so that it was in contact with the casting drum, and cooled and solidified to obtain an unstretched laminate film. This unstretched laminate film was stretched 3.5 times in both the longitudinal and transverse directions at 95°C in a sequential biaxial stretching machine, for a total stretching magnification of 12.3 times (area-based stretching magnification). It was then heat-treated at 205°C for 3 seconds at constant length, followed by a 2% relaxation treatment in the transverse direction to obtain a biaxially oriented polyethylene terephthalate film. After uniformly cooling to 25°C, both ends of the film were trimmed using a trimming device, and the film thickness was measured using an online thickness gauge. The 1-m-wide biaxially oriented polyethylene terephthalate film was fed to a winding device equipped with the aforementioned contact roll A and the winding section shown in Figure 3, and wound onto a glass fiber-reinforced resin winding core at a winding speed of 200 m / min to a winding length of 10,000 m. The film was wound with the Layer A side in contact with the contact roll. The contact roll was pressed against the film roll with a pressure of 300 N / m and a tension of 200 N / m. The static eliminator installed in the winding section of Figure 3 was equipped with a needle-shaped electrode as the corona discharge electrode 16, the voltage applied to the high-voltage power supply was 4 kV, and the static elimination distance was 200 mm. Furthermore, air was supplied from an air nozzle at a wind speed of 10 m / s. In this way, a biaxially oriented polyethylene terephthalate film roll was obtained with a thickness of 5.0 μm, a surface roughness of 4 nm on the A layer side, and a surface roughness of 8 nm on the B layer side. The evaluation results are shown in Table 1. [Examples 2 to 5, Comparative Examples 1 to 4] A biaxially oriented polyethylene terephthalate film roll was obtained in the same manner as in Example 1, except that the contact rolls of the winding device were changed in order from contact roll B to contact roll I. The evaluation results are shown in Table 1.

[0081] [Table 1] [Industrial Applicability]

[0082] The present invention provides a contact roll that can sufficiently reduce wrinkles and static electricity in a film roll over a long period of time, even in the production of a film roll with high surface smoothness. Furthermore, by using the contact roll of the present invention, a film roll with a good quality of wound shape can be obtained. Furthermore, the contact roll of the present invention may also be used to prevent slippage between the film and a transport roll. [Explanation of symbols]

[0083] F: Film 1: Vacuum container 2: Vacuum exhaust mechanism 3: Elastic roll 4: Rotation drive means 5: Plasma generating electrode 6: Power supply 7: Gas inlet pipe 8: Contact roll 9: Core material 10: First layer (elastic layer) 11: Layer A (layer made of DLC) 12: Layer B (layer made of DLC containing silicon) 13: Transport roll 14: Winding core 15: Film roll 16: Corona discharge electrode 17: Shield electrode 18: High voltage power supply FD: Film running direction

Claims

1. A contact roll comprising a core material, a first layer made of an elastic body, and a second layer serving as an outermost layer outside the first layer, wherein when the static friction coefficient of the surface of the second layer is μ0 and the thickness of the second layer is t μm, μ0 / t is 0.25 or less, the second layer has an A layer in contact with the first layer and a B layer serving as an outermost layer, the layer A is made of diamond-like carbon, A contact roll, characterized in that the layer B is made of diamond-like carbon containing silicon.

2. 2. The contact roll according to claim 1, wherein the static friction coefficient μ0 of the surface of the second layer is 0.10 or more and 0.20 or less.

3. 2. The contact roll according to claim 1, wherein the second layer has a thickness t of 1.0 μm or less.

4. A contact roll according to any one of claims 1 to 3, characterized in that the silicon content of the B layer is 5 at% or more and 20 at% or less.

5. A film winding device comprising the contact roll according to any one of claims 1 to 4.

6. A method for manufacturing a film roll, comprising a step of winding a film using the film winding device according to claim 5.

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