Biaxially oriented polyester film roll

Abstract

To provide a polyester film roll that has less wrinkles and defects on the film surface and no winding deviation and is suitable for secondary processing such as coating and vapor deposition.SOLUTION: A polyester film roll formed by winding a biaxially oriented polyester film around a core satisfies following requirements (1)-(3). (1) The polyester film roll has an average winding hardness of the surface in the range of 500 or more and 700 or less. (2) The polyester film roll has a degree of variability of winding hardness of the surface of 1% or more and 5% or less in the film width direction. (3) The polyester film roll has a degree of variability of winding hardness of 3% or more and 10% or less from the surface to the core.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a film roll formed by winding a biaxially oriented polyester film, which has few wrinkles and defects on the film surface, no winding deviation, and is suitable for secondary processing such as coating and vapor deposition. Furthermore, the present invention relates to a polyester film roll in which the quality of the coated film after secondary processing is also excellent.

Background Art

[0002] Conventionally, polyester films have been widely used in a wide range of fields such as packaging materials and industrial materials due to their excellent mechanical strength, thermal properties, and optical properties. In particular, biaxially oriented polyester films are excellent in oxygen barrier properties, and in packaging applications such as for food, retort products, and pharmaceuticals, the requirements for oxygen barrier properties and water vapor barrier properties related to the deterioration and degradation of the contents have been increasing, and there is a problem that the contents deteriorate and degrade.

[0003] Therefore, measures have been taken to further improve the gas barrier properties of biaxially oriented polyester films used in packaging applications such as for food, retort products, and pharmaceuticals against gases such as oxygen and water vapor. As a method for improving the gas barrier properties, a method of laminating a film having good gas barrier properties such as polyvinylidene chloride or a polyethylene vinyl alcohol copolymer on the polyester film, and a method of depositing a metal such as aluminum or a metal oxide such as aluminum oxide on the biaxially oriented polyester film to form a thin film are often used. In particular, the vapor-deposited polyester film provided with the latter metal or metal oxide on the film surface is excellent in terms of heat resistance and transparency.

[0004] In addition, it is known that the gas barrier performance of the resulting vapor-deposited polyester film greatly depends on the surface state of the biaxially oriented polyester film used as the base material. Examples include those that define the surface roughness and the number of protrusions of the biaxially oriented polyester film serving as the base material (see, for example, Patent Document 1), those that define the melting sub-peak of the biaxially oriented polyester film (see, for example, Patent Document 2), and those that define the amount of oligomers generated in the film (see, for example, Patent Document 3).

[0005] However, even for biaxially oriented polyester films with the same characteristics, there were variations in the quality of the coated films after processes such as coating and vapor deposition, and sometimes the quality was outside the allowable range. Also, the cause was unknown.

[0006] As a factor that degrades the quality of the coated film, film wrinkles in the polyester film roll before unwinding from the polyester film roll purchased as a product can be cited. As a method for improving such problems, a polyester film roll with reduced core wrinkles and surface wrinkles has been proposed (Patent Document 4).

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Disclosure of the Invention

Problems to be Solved by the Invention

[0008] An object of the present invention is to improve such problems, and to provide a polyester film roll that has few wrinkles and defects on the film surface, no winding deviation, and is suitable for secondary processing such as coating and vapor deposition. Furthermore, it is to provide a polyester film roll in which the quality of the coated film after secondary processing is also excellent.

Means for Solving the Problems

[0009] As a result of intensive studies by the present inventors to achieve such an object, the variation in the winding hardness from the core to the surface of a polyester film roll formed by winding a biaxially oriented polyester film around a core is made constant, and the winding hardness of the surface of the film roll is set within a specific range, whereby a polyester film roll with few wrinkles and defects on the film surface, no winding deviation, and suitable for secondary processing such as coating and vapor deposition can be provided. More preferably, a polyester film roll in which winding wrinkles, winding deviation, and spoke wrinkles on the roll end face are less likely to occur, and there are few quality defects due to charging such as static marks and discharge marks can be obtained. Therefore, it is possible to reduce troubles such as a decrease in quality due to spots and peeling of the coating or vapor deposition thin film after secondary processing, and appearance defects due to wrinkles after winding after secondary processing.

[0010] That is, the present invention has the following configuration. 1. A polyester film roll formed by winding a biaxially oriented polyester film around a core, characterized in that it satisfies the following requirements (1) to (3). (1) The average winding hardness of the surface of the polyester film roll is in the range of 500 or more and 700 or less. (2) The variation rate of the winding hardness in the film width direction of the surface of the polyester film roll is 1% or more and 5% or less. (3) The variation rate of the winding hardness from the surface to the core of the polyester film roll is 3% or more and 10% or less.

[0011] 2. The polyester film roll according to 1., wherein the thickness variation rate in the width direction of the polyester film is 10% or less. 3. The polyester film roll according to 1. or 2., wherein the coefficient of kinetic friction of both the outer winding surface and the inner winding surface of the biaxially oriented polyester film is 0.2 or more and 0.60 or less. 4. The polyester film roll according to 1. to 3., wherein the arithmetic mean height of the inner winding surface of the biaxially oriented polyester film is 0.010 μm or more and 0.050 μm or less.

[0012] 5. The polyester film roll according to any one of 1. to 4., wherein the thickness of the biaxially oriented polyester film is 5 μm or more and 40 μm or less. 6. The polyester film roll according to any one of 1. to 5., wherein the winding length of the biaxially oriented polyester film is 2000 m or more and 65000 m or less. 7. The polyester film roll according to any one of 1. to 6., wherein the width of the polyester film roll is 400 mm or more and 3000 mm or less.

[0013] 8. The polyester film roll according to any one of 1. to 7., wherein the biaxially oriented polyester film is for a vapor-deposited film substrate.

Advantages of the Invention

[0014] The polyester film roll of the present invention has few wrinkles and defects on the film surface, no winding deviation, and is suitable for secondary processing such as coating and vapor deposition. More preferably, a polyester film roll in which winding wrinkles, winding deviation, and spoke wrinkles are less likely to occur and there are few quality defects due to charging such as static marks and discharge traces can be obtained. Therefore, it is possible to reduce troubles such as a decrease in quality due to spots and omissions of the coating or vapor-deposited thin film after secondary processing, and appearance defects due to wrinkles after winding after secondary processing.

[0015] More preferably, it is possible to obtain a polyester film roll in which winding wrinkles, winding displacement, and spoke wrinkles on the roll end face do not occur during winding, and there are few quality defects due to charging such as static marks and discharge marks. In this case, it is possible to reduce troubles such as appearance defects due to evaporation spots during vapor deposition processing and wrinkles during winding after vapor deposition, and generation of defective products in post-processing such as spots and missing parts due to partial springback of the vapor deposition thin film. Especially in recent years, in order to improve the processing efficiency of biaxially oriented polyester films, the width and length of polyester film rolls have been increased. However, even if film rolls are manufactured again while slitting a large-sized film roll of the size wound first into smaller pieces, it is possible to improve the quality uniformity among the respective film rolls. Further, when the film roll is lengthened, since the polyester film has electrical insulation properties, it is in a condition where it is easily charged due to contact and peeling with the conveying roll in the film manufacturing process, but the quality can still be easily maintained.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0017] Hereinafter, the present invention will be described in detail. The biaxially oriented polyester film in the present invention is composed of the following polyester resin, preferably a polyester resin composition containing the following fine particles or / and the following additives. The polyester resin constituting the biaxially stretched polyester film in the present invention is a polymer synthesized from a dicarboxylic acid or its ester-forming derivative and a diol or its ester-forming derivative. For example, polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate can be mentioned, and polyethylene terephthalate is preferable from the viewpoints of mechanical properties, heat resistance, cost, etc.

[0018] In addition, other components may be copolymerized with these polyesters as long as the object of the present invention is not impaired. Specifically, as the copolymerization components, among the dicarboxylic acid components, isophthalic acid, naphthalenedicarboxylic acid, 4,4-diphenyldicarboxylic acid, adipic acid, sebacic acid and its ester-forming derivatives, etc. can be mentioned. Also, as the diol components, diethylene glycol, hexamethylene glycol, neopentyl glycol, cyclohexanedimethanol can be mentioned. Also, polyoxyalkylene glycols such as polyethylene glycol and polypropylene glycol can be mentioned. The copolymerization amount is preferably within 10 mol% per repeating unit constituting, and more preferably within 5 mol%.

[0019] As a method for producing the polyester resin constituting the biaxially stretched polyester film in the present invention, first, using the aforementioned dicarboxylic acid or its ester-forming derivative and a diol or its ester-forming derivative as the main starting materials, an esterification or transesterification reaction is carried out according to a conventional method, and then a polycondensation reaction is carried out under high temperature and reduced pressure. Examples of the production method include this method.

[0020] The intrinsic viscosity of the polyester resin constituting the biaxially oriented polyester film in the present invention is preferably in the range of 0.50 to 0.9 dl / g, more preferably in the range of 0.55 to 0.8 dl / g, from the viewpoints of film-forming properties and recyclability, etc.

[0021] In the biaxially oriented polyester film of the present invention, in order to improve the slipperiness during film production or secondary processing such as vapor deposition, it is preferable to add fine particles as a lubricant. The coefficient of kinetic friction and the coefficient of static friction can be used as indices of slipperiness. Examples of the fine particles to be used include inorganic fine particles and organic fine particles. Examples of the inorganic fine particles include particles composed of silica, alumina, titanium dioxide, calcium carbonate, kaolin, and barium sulfate. Examples of the organic fine particles include acrylic resin particles, melamine resin particles, silicone resin particles, and fine particles composed of crosslinked polystyrene. The average particle diameter of the fine particles preferably has a weight average particle diameter measured by a Coulter counter in the range of 0.05 to 3.0 μm. When the weight average particle diameter is 0.05 μm or more, it is easy to increase the coefficient of kinetic friction, and when the weight average particle diameter is 3.0 μm or less, it is easy to prevent the coefficient of kinetic friction from becoming too high.

[0022] As the fine particles for adjusting the coefficient of kinetic friction and the coefficient of static friction of the biaxially oriented polyester film in the present invention, inorganic fine particles composed of silica, calcium carbonate, or alumina, or organic fine particles composed of polymethacrylate, polymethyl acrylate, or a derivative thereof are preferable from the viewpoint of reducing the haze of the biaxially oriented polyester film. Inorganic fine particles composed of silica or calcium carbonate are more preferable, and inorganic fine particles composed of silica are particularly preferable.

[0023] As a method of blending the fine particles in the biaxially oriented polyester film of the present invention, for example, it can be added at any stage of manufacturing the polyester resin, but it is preferably added as a slurry dispersed in ethylene glycol or the like at the stage of esterification or at the stage after the transesterification reaction and before the start of the polycondensation reaction, and the polycondensation reaction is allowed to proceed. Further, it is also preferable to carry out by a method of blending a slurry of particles dispersed in ethylene glycol or water or the like and a polyester resin raw material using a kneading extruder with a vent, or a method of blending the dried particles and the polyester resin raw material using a kneading extruder.

[0024] The lower limit of the content of the fine particles in the biaxially oriented polyester film of the present invention is preferably 100 ppm by weight, more preferably 900 ppm by weight, and particularly preferably 1500 ppm by mass. When the content of the fine particles is 100 ppm by weight or more, it is easy to lower the coefficient of kinetic friction and the coefficient of static friction, and when the master roll is slit and the film is wound around the core, the amount of air entrained does not increase, and after the air in the concave portions between the protrusions formed between the films and on the film surface in the wound film roll has escaped, the film is less likely to slacken or wrinkle. The upper limit of the content of the fine particles is preferably 20,000 ppm by weight, more preferably 2000 ppm by weight, and particularly preferably 1800 ppm by weight. When the content of the fine particles is 20,000 ppm by weight or less, not only is the transparency less likely to decrease, but also the coefficient of kinetic friction of the film does not become too low, and misalignment of the end face is less likely to occur.

[0025] Further, in the biaxially oriented polyester film of the present invention, a small amount of other polymers, antioxidants, heat stabilizers, antistatic agents, ultraviolet absorbers, plasticizers, pigments or other additives may be contained within a range that does not impair the object of the present invention.

[0026] [Method for producing biaxially oriented polyester film] Preferred examples of the biaxially oriented polyester film in the present invention are described below, but are not limited thereto. For example, it can be obtained by melt-extruding a composition mainly composed of the above polyester resin using an extruder to form an unstretched film, and manufacturing the unstretched film by the method shown below.

[0027] When melt-extruding the polyester resin composition, it is preferable to dry the polyester resin composition using a dryer such as a hopper dryer or a paddle dryer, or a vacuum dryer. After drying the polyester resin composition in this way, use an extruder to melt it at a temperature of 200 to 300°C and extrude it into a film shape. Alternatively, the polyester resin, fine particles, and additives may be fed out by separate extruders, mixed and melted after merging, and then extruded into a sheet shape. When extruding the molten resin composition, any existing method such as the T-die method or the tubular method can be adopted.

[0028] Then, by rapidly cooling the sheet-like molten polyester resin composition after extrusion, the unstretched sheet can be obtained. As a method for rapidly cooling the molten polyester resin composition, a method of casting the molten polyester resin composition onto a rotating drum from a die and rapidly cooling and solidifying it to obtain a substantially unoriented resin composition sheet can be preferably adopted. The temperature of the rotating drum is preferably set at 30°C or lower.

[0029] Furthermore, it can be achieved by appropriately combining film-forming conditions such as stretching conditions in the longitudinal and width directions, heat-setting conditions, and heat-relaxing conditions for the obtained unstretched sheet. This will be described in detail below. The longitudinal direction means the direction in which the unstretched sheet travels, and the width direction means the direction perpendicular to it.

[0030] The stretching method can be simultaneous biaxial stretching in which stretching in the longitudinal and width directions is performed simultaneously, or sequential biaxial stretching in which stretching in either the longitudinal or width direction is performed first. However, sequential biaxial stretching is most preferable in terms of high film-forming speed and high productivity.

[0031] As the longitudinal stretching temperature, from the viewpoint of making the widthwise variation of the curl hardness on the film surface constant, it is preferably in the range of (Tg + 15) to (Tg + 55)°C, and as the stretching ratio, it is preferably in the range of 3.3 to 4.7 times. When the stretching temperature is (Tg + 55)°C or lower and further 3.3 times or more, the balance of molecular orientation in the longitudinal direction and the width direction is good, and the physical property difference between the longitudinal direction and the width direction is small, which is preferable. Also, the flatness of the obtained biaxially stretched polyester film is preferably good. On the other hand, when the stretching temperature in the MD direction is (Tg + 15)°C or higher and further the stretching ratio is 4.7 times or lower, the shrinkage stress does not increase too much and the bowing is reduced, which is preferable.

[0032] Also, in the longitudinal stretching, in the method of stretching in multiple stages between a plurality of rolls instead of one-stage stretching, since it is gradually stretched in the longitudinal direction while controlling the stretching speed, the physical property difference in the film width direction can be further reduced. From the viewpoints of effects, equipment, and cost, two-stage to five-stage stretching is preferable.

[0033] When stretching in the width direction, both ends of the film stretched in the longitudinal direction of the unstretched film are gripped with clips and guided to a tenter device capable of heating, and after heating the film to a predetermined temperature by hot air, the film is stretched in the width direction by widening the distance between the clips while conveying in the longitudinal direction. When the stretching temperature in the width direction is Tg + 5°C or higher, breakage is less likely to occur during stretching, which is preferable. Also, when it is Tg + 40°C or lower, uniform stretching in the width direction is easy, and the thickness unevenness in the width direction is less likely to increase, so the widthwise variation of the curl hardness on the film roll surface is less likely to increase, which is preferable. More preferably, it is Tg + 8°C or higher and Tg + 37°C or lower, and still more preferably, it is Tg + 11°C or higher and Tg + 34°C or lower. The stretching ratio in the width direction is preferably 2 times or more and 6 times or less. When the stretching ratio is 2 times or more, a high yield can be easily obtained in terms of material balance, the mechanical strength does not decrease, the thickness unevenness in the width direction does not easily increase, and the variation in the winding hardness in the width direction of the film roll is not likely to occur, which is preferable. Also, when the stretching ratio is 6 times or less, it is preferable because it is less likely to break during stretch film formation.

[0034] As the heat setting temperature of the film stretched in the width direction, 220 to 245 °C is preferable. When the heat setting temperature is 245 °C or lower, it is preferable because boiling is less likely to increase. On the other hand, when it is 220 °C or higher, the thermal shrinkage rate in both the longitudinal and width directions does not become too high, and the thermal dimensional stability during vapor deposition processing is improved, which is preferable. Also, when the TD heat setting temperature is 245 °C or lower, it is preferable because boiling is less likely to increase.

[0035] In the heat relaxation treatment step, until the film shrinks due to heat relaxation, the restraining force in the width direction decreases and the film sags due to its own weight, or the film may bulge due to the accompanying air flow of the hot air blown out from the nozzles installed above and below the film. Therefore, the film is in a situation where it is very likely to fluctuate up and down. For this reason, in this heat relaxation treatment step, depending on the conveyance state of the film, the amount of change in the orientation angle and the diagonal thermal shrinkage rate difference of the biaxially stretched polyester film obtained fluctuates greatly. As a method to reduce these, for example, it can be mentioned that by adjusting the wind speed of the hot air blown out from the upper and lower nozzles, the film is kept parallel. As the relaxation rate in the width direction, 4 to 8% is preferable. When the heat relaxation rate is 4% or more, the thermal shrinkage rate in the width direction of the obtained biaxially stretched polyester film does not become too high, and the dimensional stability during vapor deposition processing is good, which is preferable. On the other hand, when the heat relaxation rate is 8% or less, the tensile stress (bowing phenomenon) acting in the direction opposite to the traveling direction of the film at the center of the film in the width direction does not become too large, and the film thickness variation rate in the width direction does not increase. Therefore, the variation rate in the width direction of the average winding hardness on the surface of the film roll does not increase, which is preferable. The heat setting step and the heat relaxation treatment step may be performed separately or simultaneously.

[0036] The wide biaxially oriented polyester film stretched and formed by the above method is wound by a winder device to produce a master roll. The width of the master roll is preferably 5000 mm or more and 10000 mm or less. When the roll width is 5000 mm or more, the cost per film area is preferably reduced in the subsequent slitting process, vapor deposition process, and printing process. The winding length of the master roll is preferably 10000 m or more and 100000 mm or less. When the roll winding length is 5000 mm or more, the cost per film area is preferably reduced in the subsequent slitting process, vapor deposition process, and printing process.

[0037] The film thickness of the biaxially oriented polyester film roll of the master roll is preferably 5 to 40 μm. When it is 5 μm or more, the strength and firmness of the film do not decrease, and it is preferable that wrinkles are less likely to occur in the film roll. On the other hand, even if the film thickness is thick, there is no problem as a film roll, but it is preferably thinned from the viewpoint of cost. The film thickness is more preferably 8 to 30 μm, and particularly preferably 9 μm to 20 μm.

[0038] The thickness variation rate in the width direction of the biaxially oriented polyester film of the master roll is preferably 10% or less. Also, the thickness variation rate shall be measured using a continuous contact type thickness gauge as shown in the examples. The overall thickness unevenness in the width direction shall be calculated by the following formula 1. When the film thickness variation rate is 10% or less, the winding hardness in the width direction is likely to be constant, which is preferable. The smaller the value of the thickness variation rate, the more preferable. Film thickness variation rate in the width direction ={(Maximum thickness - Minimum thickness)÷Average thickness}×100(%) ··· Formula 1

[0039] The static friction coefficient and the kinetic friction coefficient between the film surfaces of the outer winding surface and the inner winding surface of the biaxially oriented polyester film of the master roll are preferably both 0.20 or more and 0.60 or less, more preferably 0.23 or more and 0.50 or less, and most preferably 0.25 or more and 0.40 or less. When it is 0.20 or more, the film does not slip too much, and winding deviation is less likely to occur, which is preferable. Also, when it is 0.60 or less, when the master roll is slit and the film is wound around the core, the amount of air entrapped during slitting does not increase, and even if the air between the films in the film roll after winding and in the concave portions between the protrusions formed on the film surface escapes, the film is less likely to have slack or wrinkles.

[0040] The arithmetic mean height of the inner winding surface of the biaxially oriented polyester film of the master roll is preferably 0.010 to 0.050 μm. When the arithmetic mean height of the inner winding surface of the film surface is 0.010 μm or more, it is difficult for the films in the film roll to adhere (blocking phenomenon), it is difficult for abnormal sounds (the sound of the adhered film peeling off) to occur during unwinding from the master roll, and it is difficult for the film to break, which is preferable. Also, when the arithmetic mean height of the inner winding surface of the film surface is 0.050 μm or less, the number of surface protrusions leading to peeling or defects of the coating or vapor deposition thin film after secondary processing on the surface of the biaxially oriented polyester film in the film roll slit and wound around the core is reduced, and the quality of the coated film is less likely to deteriorate, which is preferable. The arithmetic mean height of the outer winding surface of the film surface is preferably in the same range.

[0041] [Film roll] In the slit process described below, the above master roll is slit into the width described below while applying tension in the longitudinal direction of the film and further applying pressure by contact control from above the film roll, and is wound around the core and shipped as a polyester film roll suitable for the product.

[0042] The width of the polyester film roll of the present invention is preferably 400 mm or more and 3000 mm or less. When the width of the film roll is 400 mm or more, the cost per film area does not increase in subsequent vapor deposition processing or printing processing, which is preferable. Also, when the width of the film roll is 3000 mm or less, it is preferable from the viewpoint of handling properties in secondary processing. The width of the film roll is more preferably 500 mm or more and 2500 mm or less, and particularly preferably 600 mm or more and 2300 mm or less. The winding length of the master roll is preferably 10000 m or more and 100000 mm or less. When the winding length of the roll is 5000 mm or more, the cost per film area is low in subsequent slitting processes, vapor deposition processing, or printing processing, which is preferable.

[0043] The biaxially stretched polyester film unwound from the obtained master roll is slit to a specified width and winding length using a slitter and wound around a core to obtain a polyester film roll. The core used for the biaxially oriented polyester film roll of the present invention is not particularly limited, and usually, cylindrical cores made of plastic, metal, or paper tubes with sizes such as 3 inches (37.6 mm), 6 inches (152.2 mm), and 8 inches (203.2 mm) in diameter can be used.

[0044] The tension applied in the longitudinal direction of the film in the slitting process and the pressure applied by contact control from above the film roll (hereinafter referred to as surface pressure) are particularly important in controlling the winding hardness on the film roll surface and in the film roll. However, examples of specific suitable slitting conditions will be described in the order of progress of the slitting process.

[0045] [At the start of winding] (1) The winding tension (initial tension) applied to the film at the start of winding onto the core is preferably 50 N / m or more and 100 N / m or less, and more preferably 60 N / m or more and 80 N / m or less. If the initial tension is 50 N / m or less, the winding hardness of the core becomes low, and it is preferable because wrinkles are less likely to occur when the film running speed increases at the start of winding. Also, if it is 110 N / m or less, the hardness does not become too high, and the paper tube that becomes the winding core of the film roll is less likely to deform, which is preferable.

[0046] (2) The surface pressure (initial surface pressure) of the contact control at the start of winding is preferably set to 500 N / m or more and 800 N / m or less. When the initial surface pressure is 500 N / m or more, there is an effect of pressing the film when the film running speed increases at the start of winding, and wrinkles are less likely to occur, which is preferable. Furthermore, the winding does not become too soft. For example, when the film roll is stored in a warehouse for a long period (e.g., half a year), the distortion of the film roll, the slack and wrinkles of the film caused by the air trapped in the film roll escaping between the films during slitting are less likely to occur, which is preferable. Also, if it is 800 N / m or less, the hardness of the film roll does not become too high, and the paper tube that becomes the core of the roll is less likely to deform, which is preferable. More preferably, it is 550 N / m or more and 750 N / m or less, and particularly preferably 600 N / m or more and 700 N / m or less.

[0047] [From the start of winding to a winding diameter of 200 - 300 mm] (1) The acceleration of the film running speed from the start of winding to a winding diameter of 200 - 300 mm is 50 m / min 2 or more and 200 m / min 2 or less, and preferably 75 m / min 2 or more and 175 m / min 2 or less is more preferable. When the acceleration of the film running speed is 50 m / min 2 or more, wrinkles are less likely to occur near the core (core layer) when the film running speed increases, which is preferable. Also, when the acceleration is 200 m / min 2The following is preferred because it is less likely to cause end face deviation near the core (core layer) when the film running speed increases. If wrinkles or end face deviation occur near the core (core layer), the wrinkles and end face deviation will continue to occur thereafter. The winding diameter referred to here means the vertical distance (mm) obtained by subtracting the diameter of the core from the diameter of the wound film roll.

[0048] [From a winding diameter of 200 to 300 mm until the end of winding] (1) The film running speed from a winding diameter of 200 to 300 mm is preferably constant, and the film running speed is preferably 400 m / min or more and 800 m / min or less, and more preferably 500 m / min or more and 700 m / min or less.

[0049] [From the start of winding until the end of winding] (1) The winding tension applied to the film from the start of winding until the end of winding is preferably constant or gradually increasing, preferably 50 N / m or more and 100 N / m or less, and more preferably 60 N / m or more and 80 N / m or less. (2) The surface pressure of the contact control from the start of winding until the end of winding is preferably constant or gradually increasing, and the surface pressure increase rate indicating the ratio of the surface pressure at the end of winding (final surface pressure) to the surface pressure at the start of winding (initial surface pressure) of the contact control is preferably 100% or more and 190% or less. The surface pressure increase rate is calculated by the following formula 2. Surface pressure increase rate = (surface pressure at the end of winding ÷ initial surface pressure) × 100 ··· Formula 2

[0050] When the surface pressure increase rate is 200% or less, as the winding progresses, the difference in the change in winding hardness when changing the surface pressure from the initial surface pressure to the final surface pressure is small. Therefore, it is preferable that wrinkles having a flower pattern called spoke-like wrinkles or a shape like the spokes of a wheel do not easily occur on the end face of the film roll. More preferably, it is 110% or more and 180% or less, and particularly preferably 120% or more and 170% or less. The greater the rate of increase in surface pressure during winding, the greater the difference in the change in winding hardness in the film roll radius direction, the greater the stress applied in the film roll radius direction during film winding, and it is presumed that this is related to the elongation in the width direction of the film near the end face of the film roll of that layer, resulting in spoke wrinkles. It is preferable that the rate of variation in winding hardness from the surface to the core of the polyester film roll is 3% or more and 10% or less.

[0051] [At the end of winding] The surface pressure (final surface pressure) of the contact control at the end of winding is preferably 700 N / m or more and 950 N / m or less. When the final surface pressure is 700 N / m or more, the winding does not become too soft, and displacement of the end face of the film roll surface layer is less likely to occur.

[0052] [Characteristics of the polyester film roll] [Winding length] The winding length of the polyester film roll of the present invention is preferably 2000 m or more and 65000 m or less. Here, the winding length refers to the length of the film in the longitudinal direction from the film end at the outermost surface of the film roll, where the film is unwound, 5 m is removed from the film end, to a point 100 m in the longitudinal direction toward the outermost surface of the film roll from the film end fixed to the core. When the winding length is 2000 m or more, the labor of frequently replacing the film roll in the printing process is reduced, which is preferable in terms of cost. Also, although a longer winding length is preferable, when it is 65000 m or less, the roll diameter does not become too large, the roll weight does not become too heavy, and the handling property does not deteriorate, which is preferable. [Winding width] The winding width of the polyester film roll of the present invention is preferably 400 mm or more and 3000 mm or less. Here, the winding width refers to the shortest distance from one end of the film roll surface to the other end. When the winding width is 400 mm or more, the labor of frequently replacing the film roll in the printing process is reduced, which is preferable in terms of cost. Also, although a longer winding width is preferable, when it is 3000 mm or less, the roll width does not become too large, the roll weight does not become too heavy, and the handleability does not deteriorate, which is preferable. The winding width is more preferably 1000 mm or more and 3000 mm or less, and even more preferably 1500 mm or more and 3000 mm or less.

[0053] [Winding hardness] When measuring the average winding hardness at intervals of 200 mm in the film width direction on the surface of the polyester film roll of the present invention, it is preferable that the average winding hardness is in the range of 500 or more and 700 or less. "The surface of the film roll" refers to the surface of the film roll after unwinding the film from the film end of the outermost surface of the film roll and removing the range from the film end to 5 m. The measurement points in the width direction on the surface of the film roll are the positions moved 5 cm in the width direction from the film end side where the winding direction of the film from the roll core of the film roll to the outermost surface is clockwise, and then the positions moved 200 mm each. At this time, if the last position is less than 5 cm from the film end, it shall be excluded from the calculation. In addition, the winding hardness shall be measured using the hardness tester Parotester 2 manufactured by Swiss Processo. When the average winding hardness in the width direction is 500 or more, the winding of the film roll is less likely to come loose, or the end faces are less likely to shift, and the end faces are likely to be aligned (so-called no winding shift). Further, when the average winding hardness in the width direction is 700 or less, local strong charging or discharge marks called static marks caused by electrostatic discharge or the like are less likely to occur on the film surface inside the film roll, and unevenness or peeling of the coating or vapor deposition thin film is less likely to occur during secondary processing such as coating or vapor deposition, and it is preferable because the quality is less likely to deteriorate. The average winding hardness is more preferably 650 or more and 690 or less. In addition, the winding hardness in the present invention is measured using the hardness tester Parotester 2 manufactured by Swiss Processo.

[0054] When measuring the winding hardness on the surface of the polyester film roll of the present invention at intervals of 200 mm in the width direction of the film roll, it is preferable that the variation rate of the winding hardness is 1% or more and 5% or less. The variation rate of the winding hardness shall be calculated by the following formula 3. Variation rate of winding hardness in the width direction of the film roll =(Maximum value of winding hardness - Minimum value of winding hardness) ÷ Hardness × 100 (%) ··· Formula 3

[0055] When the variation rate of the winding hardness exceeds 5%, winding shift is likely to occur in the film roll, which causes partial sagging in the film roll, and deformation or wrinkles of the film are likely to occur in the tension applied during secondary processing such as coating or vapor deposition, and a stable coating or vapor deposition thin film cannot be formed, which is not preferable. Although 0% is ideal for the variation rate of the winding hardness, it is difficult to achieve substantially, and at most 1% is considered the lower limit.

[0056] When measuring the hardness variation by dividing the polyester film roll of the present invention into 10 equal parts in the longitudinal direction from the surface to the core, it is preferable that the hardness variation is 3% or more and 10% or less. The hardness variation shall be calculated by the following formula 4. Hardness variation (longitudinal direction) =(Maximum value of hardness - Minimum value of hardness) ÷ Hardness × 100 (%) ··· Formula 4

[0057] Here, dividing the polyester film roll longitudinally into 10 parts from the surface to the core means unwinding the film from the film end at the outermost surface of the film roll, removing 5 m from the film end, and then dividing the portion from the film end fixed to the core to 100 m longitudinally toward the outermost surface of the film roll into 10 parts. The film is wound up to each division position, and the winding hardness of the surface of the film roll is measured at intervals of 200 mm in the film width direction. The measurement points in the width direction on the surface of the film roll are the positions moved 5 cm in the width direction from the film end side where the winding direction of the film from the core to the outermost surface of the film roll rotates clockwise, and the positions moved 200 mm further from there. At this time, if the last position is less than 5 cm from the film end, it shall be excluded from the calculation. When the variation rate of the winding hardness exceeds 10%, the difference in the winding hardness between layers at different positions in the film roll becomes large. As a result, the stress applied in the roll radius direction during film winding increases, making it easier for spoke wrinkles to occur or for partial sagging to occur in the film, and making it easier for film deformation and wrinkles to occur in the tension during secondary processing such as coating or vapor deposition, and the quality of the coated film is likely to deteriorate, which is not preferable. Although 0% is ideal for the variation rate of the winding hardness, it is difficult to achieve substantially, and at most 3% is considered the lower limit.

[0058] [Film Thickness] The arithmetic mean height of the inner winding surface of the film of the polyester film roll of the present invention is preferably 0.010 to 0.050 μm. If the arithmetic mean height is 0.010 μm or less, adhesion (blocking phenomenon) between the films inside the roll occurs, and abnormal noise (the sound of the adhered film peeling off) occurs or the film breaks when the polyester film roll is unwound for secondary processing, which is not preferable. Also, if the arithmetic mean height of the film exceeds 0.050 μm, the quality of the coated film after secondary processing such as coating or vapor deposition is likely to deteriorate, which is not preferable. The film thickness of the polyester film roll of the present invention is preferably 5 to 40 μm. When it is 5 μm or more, the strength deficiency and firmness as a film are significantly less likely to decrease, and wrinkles are less likely to occur in the film in the film roll, which is preferable. On the other hand, even if the film thickness is thick, there is no problem as a film roll, but it is preferable to reduce the thickness from the viewpoint of cost. The film thickness is more preferably 8 to 30 μm, and particularly preferably 9 μm to 20 μm.

[0059] [Film thickness variation rate] The thickness variation rate of the biaxially oriented polyester film in the width direction of the polyester film roll of the present invention is preferably 10% or less. Also, the thickness variation rate shall be measured using a continuous contact type thickness gauge as shown in the examples. The thickness variation rate in the width direction of the film shall be measured continuously in the width direction at 5 m / sec using a continuous thickness measuring device, and shall be calculated by the following formula 1. It is preferable that the thickness variation rate in the width direction of the film is 10% or less because wrinkles in the film are less likely to occur. The smaller the thickness variation rate in the width direction of the film, the more preferable. Thickness variation rate in the width direction of the film ={(Maximum value of thickness - Minimum value of thickness)÷Average thickness}×100 (%) ··· Formula 1

[0060] [Arithmetic mean height] The arithmetic mean height of the inner winding surface of the film of the polyester film roll of the present invention is preferably 0.010 to 0.050 μm. When the arithmetic mean height is 0.010 μm or less, adhesion (blocking phenomenon) between the films in the roll occurs, and abnormal noise (the sound of the adhered film peeling off) occurs when the polyester film roll is unwound for secondary processing, or the film breaks, which is not preferable. Also, when the arithmetic mean height of the film exceeds 0.050 μm, the quality of the coated film after secondary processing such as coating or vapor deposition is likely to deteriorate, which is not preferable. [Coefficient of static friction, coefficient of kinetic friction]

[0061] The static friction coefficient and kinetic friction coefficient between the film surfaces of the outer winding surface and the inner winding surface of the biaxially oriented polyester film of the polyester film roll of the present invention are preferably both 0.20 or more and 0.60 or less, more preferably 0.23 or more and 0.50 or less, and most preferably 0.25 or more and 0.40 or less. If it is lower than 0.20, it will slip too much and cause winding deviation, which is not preferable. Also, if it is greater than 0.60, the amount of air entrained during slitting will increase, and when winding the film roll, relaxation and wrinkles may easily occur due to air escape from the concave part.

[0062] [Winding deviation of film roll] At the end face of the film roll, the height of the unevenness is preferably 3 mm or less, and more preferably 2 mm or less. When the height of the unevenness is 3 mm or less, it is difficult for wrinkles to form in the film, and the film runs smoothly during secondary processing.

[0063] [Wrinkles of film roll] When taking an A4-sized film from two locations, 100 m in the film roll surface direction, from the outermost layer of the film roll immediately after manufacturing and from the film end fixed to the core after unwinding the film roll, and observing it under a fluorescent lamp, it is preferable that the back of the wrinkle cannot be seen.

[0064] [Spoking wrinkles on the film roll end face] Measure the length of the flower pattern or spoke-shaped wrinkles on the end face of the film roll. It is preferable that there are no wrinkles with a length of 30 mm or more. In this case, spots and peeling of the coating or vapor deposition thin film are likely to be reduced after secondary processing.

[0065] [Static marks] Install the film roll on the slitter, unwind the film from the film end on the outermost surface of the film roll, remove 4 m from the film end, and then sample the film at a length of 10 cm in the longitudinal direction and 10 cm in the central part in the width direction. When visualizing the charging state of the film surface using the charge distribution determination toner manufactured by Kasuga Electric Co., Ltd., it is preferable that no locally strong charging or discharge marks are visible. In this case, after secondary processing, the coating and the deposition thin film are less likely to have spots or peeling.

Example

[0066] Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited to the embodiments in any way, and can be appropriately changed without departing from the spirit of the present invention.

[0067] The evaluation method of the polyester resin is as follows. [Glass transition temperature (Tg)] Using a differential scanning calorimeter (DSC6220 type manufactured by SII NanoTechnology Inc.), the sample was melted to 280 °C in a nitrogen atmosphere, held for 5 minutes, then rapidly cooled with liquid nitrogen, and measured under the condition of a heating rate of 20 °C / min from room temperature.

[0068] [Intrinsic viscosity (IV)] 0.2 g of polyester was dissolved in 50 ml of a mixed solvent of phenol / 1,1,2,2-tetrachloroethane (60 / 40 (weight ratio)), and measured using an Ostwald viscometer at 30 °C. The unit is dl / g.

[0069] The evaluation method of the polyester film roll is as follows. [Film thickness] Measured using a dial gauge in accordance with JIS K7130-1999 Method A.

[0070] [Film thickness variation rate] A film roll was installed on a slitter. After that, the film was unwound from the film end at the outermost surface of the film roll, and after removing 1 m from the film end, the film was sampled in the full width in the width direction and with a length of 40 mm in the longitudinal direction. Using a film tester continuous thickness measuring device manufactured by Fuji Works, the thickness in the width direction was continuously measured at 5 m / sec. The thickness variation rate was calculated by the following formula 1. Thickness variation rate in the width direction of the film = {(maximum thickness - minimum thickness) ÷ average thickness} × 100 (%) ··· Formula 1

[0071] [Arithmetic mean height] A film roll was installed on a slitter. After that, the film was unwound from the film end at the outermost surface of the film roll, and after removing 2 m from the film end, the film was sampled in the central part 10 cm in the width direction and with a length of 10 cm in the longitudinal direction, and a white laser interferometer (NEW VIEW8300) manufactured by Zygo was used. A 20-fold lens was attached to the interferometer and scanning was performed to measure the arithmetic mean height (μm). The measurement was performed in the range of 0.82 μm in the MD direction and 0.82 μm in the width direction on one surface, and the surface excluding foreign matters such as unmelted materials and dust was targeted. The measurement location was the average value measured at 10 arbitrary points on a 10 cm × 10 cm sample, which was used as the measured value.

[0072] [Coefficient of friction] A film roll was installed on a slitter. After that, the film was unwound from the film end at the outermost surface of the film roll, and after removing 3 m from the film end, the film was sampled in the central part 10 cm in the width direction and with a length of 10 cm in the longitudinal direction. In accordance with JIS K-7125, using a tensile testing machine (Tensilon RTG-1210 manufactured by A&D), the static friction coefficient and kinetic friction coefficient when the inner surface and outer surface of the film roll were joined were determined under the environment of 23°C and 65% RH. The weight of the thread (weight) wound around the upper film was 1.5 kg, and the size of the bottom area of the thread was 39.7 mm2. Also, the tensile speed during friction measurement was 200 mm / min.

[0073] [Static Mark] The film roll was installed on the slitter. Then, the film was unwound from the film end at the outermost surface of the film roll, and after removing 4 m from the film end, the film was sampled at a length of 10 cm in the central part in the width direction and 10 cm in the longitudinal direction. Using the charge distribution determination toner manufactured by Kasuga Electric Co., the charge state on the film surface was visualized. When locally strong charging or discharge marks were visible, it was determined as having static marks (×), and when not visible, it was determined as having no static marks (○). After the measurement, the film was rewound to the intermediate layer with the slitter and the charge evaluation of the film roll was performed by the method described above. Further, the film was rewound to the core layer and the charge evaluation of the film roll was repeatedly performed.

[0074] [Surface Winding Hardness of Film Roll] The hardness of the film roll was measured using the hardness tester Parotester 2 manufactured by Processo, Switzerland. Specifically, the film roll of the present invention produced by winding with a slitter was evaluated while repeatedly unwinding the roll and measuring the hardness using a film unwinder. The hardness of the outermost layer of the roll was measured at intervals of 200 mm in the width direction of the roll after removing 5 m of film from the roll, and the average of the winding hardness was obtained. "The surface of the film roll" shall refer to the surface of the film roll after unwinding the film from the film end at the outermost surface of the film roll and removing the range up to 5 m from the film end. The measurement points in the width direction on the surface of the film roll are the positions moved 5 cm in the width direction from the film end side where the winding direction of the film from the core of the film roll to the outermost surface is clockwise, and the positions further moved 200 mm each. At this time, if the last position is less than 5 cm from the film end, it shall be excluded from the calculation.

[0075] [Variation Rate of Winding Hardness in Width Direction on Film Roll Surface] The value calculated by the following formula 3 was used with the value obtained in (1). Variation rate of winding hardness in width direction on film roll surface =(Maximum value of roll hardness - Minimum value of roll hardness) ÷ Hardness × 100 (%) ··· Equation 3

[0076] [Variation rate of roll hardness in the longitudinal direction of the film roll] Unwind the film from the film end at the outermost surface of the film roll, remove 5 m from the film end, and divide the 100 m section in the longitudinal direction from the film end fixed to the core to the outermost surface of the film roll into 10 equal parts. Wind up the film to each division position, measure the roll hardness on the surface of the film roll at intervals of 200 mm in the film width direction in the same manner as in (1) above, and use the value calculated by the following Equation 42. [Variation rate of roll hardness in the longitudinal direction of the film roll] =(Maximum value of hardness - Minimum value of hardness) ÷ Hardness × 100 (%) ··· Equation 4

[0077] [Film roll misalignment] The presence or absence of unevenness and its height were measured on the end face of the film roll. When there is no unevenness on the end face of the roll or when there is unevenness but its height is 3 mm or less, it is regarded as no misalignment (○), and when there is unevenness exceeding 3 mm, it is regarded as having misalignment (×).

[0078] [Film roll wrinkles] For the evaluation of wrinkles, take A4-sized films from two locations: the outermost layer of the film roll immediately after production and the location 100 m moved in the film roll surface direction from the film end fixed to the core after unwinding the film roll. When wrinkles can be seen when observing under a fluorescent lamp, it is determined as having wrinkles (×), and when wrinkles cannot be seen, it is determined as having no wrinkles (○).

[0079] [Spoking wrinkles on the film roll end face] Measure the length of the spoking wrinkles (flower patterns or spoke-shaped wrinkles like those of a wheel) on the film roll end face. Wrinkles with a length of 30 mm or more are regarded as NG (×), and when there are no wrinkles or when the length of the wrinkles is less than 30 mm, it is regarded as OK (○).

[0080] [Example 1] Polyethylene terephthalate (intrinsic viscosity = 0.62 dl / g, Tg = 78 °C) containing 0.15 wt% of silica with an average particle size of 2.4 μm was dried and then fed into an extruder, melted at 285 °C, extruded from a T-shaped die, and cooled and solidified on a casting drum to obtain an unstretched polyethylene terephthalate sheet. This sheet was heated to 115 °C and stretched longitudinally at a total draw ratio of 4.5 times by three-stage stretching with a draw ratio of 1.24 times in the first stage, 1.4 times in the second stage, and 2.6 times in the third stage. Subsequently, it was stretched in the width direction at a temperature of 140 °C and a draw ratio of 4.3 times, heat-set at 245 °C, and subjected to 5% heat relaxation treatment in the width direction. Then, after cutting and removing both ends of the film after the corresponding stretching, a master roll (roll length 68000 m, width 8000 mm) of a biaxially oriented polyester film with a thickness of 12 μm was produced by subjecting it to corona discharge treatment and winding it up in a roll shape with a winder. The biaxially oriented polyester film was unwound from the obtained master roll, and while slitting it to a width of 2200 mm on a winding core with a diameter of 6 inches (152.2 mm), a film roll was wound up while applying surface pressure to the film roll by contact control and tension to the film by a two-axis turret winder. The conditions at that time are shown in Table 1. Also, the physical properties and evaluation results of the obtained film roll are shown in Table 2.

[0081] [Example 2] The same procedure as in Example 1 was followed except that the slit tension was set to 105 N / m and the initial surface pressure and final surface pressure of the contact control surface pressure were changed to 700 N / m. The slit conditions are shown in Table 1, and the physical properties and evaluation results of the obtained film and master roll are shown in Table 2.

[0082] [Example 3] The same procedure as in Example 1 was followed except that the initial surface pressure of the contact control surface pressure was changed to 700 N / m. The slit conditions are shown in Table 1, and the physical properties and evaluation results of the obtained film roll are shown in Table 2.

[0083] [Example 4] The slit acceleration was 100 m / min 2It was made the same as Example 1 except that the initial surface pressure of the contact control surface pressure was changed to 700 N / m. Table 1 shows the slit conditions, and Table 2 shows the physical properties and evaluation results of the obtained film roll.

[0084] [Example 5] The slit acceleration was made 100 m / min 2 It was made the same as Example 1 except that the slit tension was made 75 N / m and the initial surface pressure of the contact control surface pressure was changed to 700 N / m. Table 1 shows the slit conditions, and Table 2 shows the physical properties and evaluation results of the obtained film roll.

[0085] [Comparative Example 1] It was made the same as Example 1 except that the initial surface pressure of the contact control surface pressure was changed to 450 N / m. Table 1 shows the slit conditions, and Table 2 shows the physical properties and evaluation results of the obtained film roll.

[0086] [Comparative Example 2] It was made the same as Example 1 except that the initial surface pressure of the contact control surface pressure was changed to 300 N / m and the final surface pressure was changed to 650 N / m. Table 1 shows the slit conditions, and Table 2 shows the physical properties and evaluation results of the obtained film roll.

[0087] [Comparative Example 3] It was made the same as Example 1 except that the final surface pressure of the contact control surface pressure was changed to 500 N / m. Table 1 shows the slit conditions, and Table 2 shows the physical properties and evaluation results of the obtained film roll.

[0088] [Comparative Example 4] It was made the same as Example 1 except that the winding tension applied to the film during winding of the winding tension was made 62 N / m and the finally applied winding tension was changed to 59 N / m. Table 1 shows the slit conditions, and Table 2 shows the physical properties and evaluation results of the obtained film roll.

[0089] [Comparative Example 5] The slit acceleration was made 250 m / min 2Except for the change to

[0090] [Comparative Example 6] The slit acceleration was set to 50 m / min 2 and the slit tension was set to 55 N / m. Except for changing the initial surface pressure of the contact control surface pressure to 350 N / m and the final surface pressure to 450 N / m, it was the same as in Example 1. The slit conditions are shown in Table 1, and the physical properties and evaluation results of the obtained film roll are shown in Table 2.

[0091] [Comparative Example 7] The slit acceleration was set to 50 m / min 2 and the slit tension was set to 85 N / m. Except for changing the initial surface pressure of the contact control surface pressure to 900 N / m and the final surface pressure to 1100 N / m, it was the same as in Example 1. The slit conditions are shown in Table 1, and the physical properties and evaluation results of the obtained film roll are shown in Table 2.

[0092] As a result of the evaluation, the films and master rolls of Examples 1 to 5 had an average hardness, hardness variation, and arithmetic mean height of the film roll within the specified ranges. Therefore, no surface layer on the roll immediately after winding up by slitting, wrinkles on the core, winding deviation, or spoke-shaped wrinkles on the end face occurred, no static marks or discharge marks occurred, and it was a film roll with excellent vapor deposition processability.

[0093] In Comparative Example 1, although the average value and variation of the hardness of the outermost layer of the film roll were within the specified ranges, the hardness variation when measured by dividing the outermost layer to the core into 10 parts was outside the specified range, and due to the high surface pressure increase rate, the difference in hardness when changing from the initial surface pressure to the final surface pressure as the winding progresses was too large, resulting in spoke-shaped wrinkles, and it was a film roll with poor secondary processability.

[0094] In Comparative Example 2, although the average value and variation of the hardness of the outermost layer of the film roll were within the specified ranges, the variation in hardness when measured by dividing the film roll into 10 parts from the outermost layer to the core was outside the specified range, and the surface pressure increase rate was high. As a result, the difference in hardness when changing from the initial surface pressure to the final surface pressure as the winding progresses was too large, causing spoke wrinkles. Also, since the initial surface pressure of the contact control surface pressure was low, winding deviation occurred, and it was a film roll with poor secondary processability.

[0095] In Comparative Example 3, since the final surface pressure was too low, winding deviation and wrinkles occurred, and it was a film roll with poor secondary processability.

[0096] In Comparative Example 4, the finally applied winding tension was low, and the difference in hardness when changing to the final surface pressure was too large, resulting in spoke wrinkles, and it was a film roll with poor secondary processability.

[0097] In Comparative Example 5, since the acceleration during film speed increase at the start of winding was high, the variation in the hardness of the outermost layer of the film roll increased, and the film roll was prone to sagging, resulting in winding deviation, and it was a film roll with poor secondary processability.

[0098] In the film of Comparative Example 6, since the average value of the hardness of the film roll was low, winding deviation occurred, and it was a film roll with poor secondary processability.

[0099] In Comparative Example 7, since the average value of the hardness of the film roll was high, static marks and discharge marks occurred, and it was a film roll with poor secondary processability.

Industrial Applicability

[0100] The biaxially oriented polyester film roll of the present invention has few wrinkles and defects on the film surface, no winding deviation, and is suitable for secondary processes such as coating and vapor deposition. Furthermore, the quality of the coated film after secondary processing is also excellent, and it can be suitably used as a film for food packaging. In particular, it is useful in wide-width and long-length film rolls with improved productivity.

[0101] [Table 1]

[0102] [Table 2]

Claims

1. A polyester film roll for food packaging, which is obtained by winding a biaxially oriented polyester film made of a polyethylene terephthalate resin composition having a thickness of 9 μm or more and optionally containing 10 mol% or less of a copolymer component around a core, with a width of 1000 mm or more and a winding length of 2000 m or more and 65000 m or less, and satisfying the following requirements (1) to (4). (1) The average winding hardness of the surface of the polyester film roll is in the range of 500 or more and 700 or less. (2) The rate of variation of the winding hardness in the film width direction on the surface of the polyester film roll is 1% or more and 5% or less. (3) The rate of variation of the winding hardness from the surface to the core of the polyester film roll is 3% or more and 10% or less. (4) It is used for coating process.

2. The polyester film roll according to claim 1, wherein the rate of thickness variation in the width direction of the biaxially oriented polyester film is 10% or less.

3. The polyester film roll according to any one of claims 1 or 2, wherein the coefficient of kinetic friction of both the outer winding surface and the inner winding surface of the biaxially oriented polyester film is 0.2 or more and 0.60 or less.

4. The polyester film roll according to any one of claims 1 to 3, wherein the arithmetic mean height of one inner winding surface of the biaxially oriented polyester film is 0.010 μm or more and 0.050 μm or less.

5. The polyester film roll according to any one of claims 1 to 4, wherein the thickness of the biaxially oriented polyester film is 40 μm or less.

6. The polyester film roll according to any one of claims 1 to 5, wherein the width of the polyester film roll is 3000 mm or less.

7. The polyester film roll according to any one of claims 1 to 6, wherein the biaxially oriented polyester film is for a vapor deposition film substrate.

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