JP2009203357A - Biaxially stretched polyester film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biaxially stretched polyester film such that it does not cause repelling or spots of a molded member raw material or the like to various coating material due to charging of a separator film for molding various molded members such as a ceramic sheet member, an electric insulating member (electric insulating resin sheet), a sheet member for retardation film, and a sheet member for optical compensator. <P>SOLUTION: The biaxially stretched polyester film has an area of charging transfer trace on the film surface of 5 to 30 cm<SP>2</SP>per 100 cm<SP>2</SP>. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a biaxially oriented polyester film having appropriate adhesion and release properties with various coating materials such as molded member raw materials.

  Conventionally, polyester films have been used favorably as release films because they have excellent solvent resistance, dimensional stability, and rigidity.

  The release film is also called a separator film, and is a base for molding various molded members such as a ceramic sheet member, an electrical insulating member (electrical insulating resin sheet), a retardation plate sheet member, and an optical compensation plate sheet member. It is a film used as a material film. The molded member is a ceramic slurry (slurry such as barium titanate) constituting the molded member on the release film, epoxy resin, polyurethane resin, polycarbonate resin, liquid crystal polymer, etc. (hereinafter collectively referred to as “molded member raw material”) To form a molding layer, which is solidified, and then peeled off the release film from the molding layer.

  Here, as the release film, a biaxially oriented polyester film has conventionally been suitably used. As the release biaxially oriented polyester film, the surface roughness and the heat shrinkage rate are specified (Patent Document 1) A film has been proposed which has improved practical characteristics as a release film by regulating the size (Patent Document 2).

  However, since the polyester film has electrical insulation, it may be charged by contact with the slitter transport roll, peeling, or the like in the film manufacturing process or processing process, which may cause problems related to the quality of the release film. For example, when locally strong charging marks or discharge marks called static marks due to electrostatic discharge are present, the forming member material is repelled or uneven when the forming member material is applied. Moreover, in order to improve the runnability of the film, the surface of the film may be intentionally given by corona treatment or the like (Patent Document 4), but the film damaged by the strong discharge is charged. Since the balance is not appropriate, there is a problem that repelling and spots of the forming member raw material occur during the application of the forming member raw material, as with the discharge trace. As a method for improving such a problem, Patent Document 3 discloses a means for eliminating charging traces and discharge traces of a film using a static elimination electrode. However, due to space limitations in a slitter transport system, It may not be right. Even if the charge is controlled by the charge eliminating electrode, the film is charged again due to friction with a transport roll or the like in the subsequent transport system. If the molding member raw material is applied onto such a charged film, the molding member raw material will also be repelled or spotted.

When a film whose surface charge is not controlled in this way is used, the forming member material is likely to be repelled and spotted in the formation of the forming layer, which may cause defects when used as a forming member, or the surface of the forming member. It will damage the appearance.
JP-A-7-227903 JP-A-6-254959 JP 2007-119605 A JP 2001-59033 A

  An object of the present invention is to provide a biaxially oriented polyester film with less repelling and spots on various coating materials such as molding member raw materials.

The present inventor has a gist in a biaxially oriented polyester film in which the area of the charge transfer mark on the surface of the film is 5 cm ² or more and 30 cm ² or less per 100 cm ² as a result of intensive studies in view of the above situation.

According to the present invention, there is provided a biaxially oriented polyester film having appropriate adhesion and peeling properties with various coating materials such as molded member raw materials.

  The biaxially oriented polyester film of the present invention is preferably used as a release film. Among release films, there is a film in which a release layer is provided on a polyester film as a base material, but the film of the present invention can be preferably used as a release film that does not include a release layer. it can.

  This is because if the release layer is provided, the film is easily charged. Since the release layer generally has slipperiness, frictional charging is likely to occur between the film and the roll in the winding process, the unwinding process, the forming member raw material coating process, and the like. When such charging occurs, foreign substances such as dust are likely to adhere to the film, causing defects in the molded member.

  That is, the foreign matter is directly transferred to the molded member and causes a defect in the molded member, and the foreign matter adheres to the release layer, so that the release property of the release layer is lowered, and a part of the release layer is partially removed. It may be transferred to the molded member. For this reason, it is preferable that the biaxially oriented polyester film of the present invention is not provided with a release layer. In the present invention, the release layer is a layer that is provided for easy separation from the molding layer, and refers to a layer that uses a silicone resin and / or a fluorine-based resin.

  When the biaxially oriented polyester film of the present invention is used as a release film, the type of the target molded member is not particularly limited, but it is particularly preferably used for electrical insulation applications such as an electrical insulation sheet (electrical insulation resin sheet). it can.

  This is because the electrical insulation sheet has a very strict control level of the release film foreign matter because it causes serious defects if foreign matter adheres to the release film for molding it. is there. That is, if foreign matter adheres to the release film, the insulation function may be deteriorated (circuit short circuit, etc.) or the circuit may be corroded. In addition, the surface state of the electrical insulating sheet is deteriorated, and when the sheet is laminated on the circuit board, a gap may be generated, and the circuit protection function may not be performed. For this reason, the film of the present invention with little adhesion of foreign substances can be particularly suitably used for the application. The release film for electrical insulation is a film used when an electrical insulation resin is laminated on a buildup substrate for a semiconductor package substrate. The electric insulating resin as the raw material of the electric insulating sheet member is applied to the biaxially oriented polyester film of the present invention, solidified, wound up, and then transferred to a substrate such as a circuit board during vacuum lamination. (Corporation Technology Research Association Editorial Planning "Converting Technology Handbook" Processing Technology Research Association, December 16, 2006, p.314-318).

  Here, the electrical insulating resin is not particularly limited as long as it is a resin used for circuit insulation, but an epoxy resin, a polyurethane resin, a silicone resin, or the like is preferably used. In particular, the biaxially oriented polyester film of the present invention is preferably used as a release film for electrical insulation in which an epoxy resin is used as an electrical insulation resin (molding member raw material).

In the present invention, the charge transfer mark is a charge transfer pattern (scratch) formed by adhesion of toner when a charged toner is applied to the film surface. The area of such a charge transfer marks is less than the film 100 cm ² per 5 cm ^2, too good adhesion between the molded layer and the release film, causing a peeling failure in the peeling step, in order to damage the molding member, 100 cm ² It is necessary to be 5 cm ² or more. Also, if the area of the charge transfer mark exceeds 30 cm ² per 100 cm ² , the wettability when applying the molding member raw material is deteriorated, the molding member raw material is repelled and mottled, and the surface shape of the molding member after the film is peeled off It is necessary to be 30 cm ² or less in order to damage the surface.

  Although the polyester film of the present invention is required to be a biaxially oriented polyester film, an unstretched (unoriented) film is biaxially oriented by sequentially biaxially or simultaneously biaxially orienting by a conventional method. It can be a polyester film.

  The polyester resin constituting the biaxially oriented polyester film of the present invention includes, as an acid component, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, adipic acid, azelaic acid, sebacic acid, decane. Aliphatic dicarboxylic acids such as dicarboxylic acids, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, and tricarboxylic acids such as trimet acid can be used. As alcohol components, ethylene glycol, diethylene glycol, polyethylene glycol, 1, 4 -Butanediol, neopentyl glycol, cyclohexanedimethanol, polytetramethylene glycol and the like can be used.

  Polyethylene terephthalate is produced by a direct polymerization method using the above acid component such as terephthalic acid and the above alcohol component such as ethylene glycol (direct weight method), or the above acid component such as dimethyl terephthalate (DMT) and a low molecule such as methanol. Any of the DMT methods using a carboxylic acid ester with alcohol and the above-mentioned alcohol such as ethylene glycol as raw materials may be used. As the transesterification catalyst in the case of the DMT method, Ca, Li, Mn, Zn, Ti or the like can be used. As a polymerization catalyst in the case of the DMT method or the direct weight method, an Ab compound such as antimony trioxide, a Ge compound such as amorphous germanium, or a Ti compound such as tetrabutyl titanate can be used. The transesterification catalyst and the polymerization catalyst are not limited to the above compounds, and the polyester film of the present invention can be obtained using a known catalyst system. For the biaxially oriented polyester film of the present invention, the polyester resin obtained by the above-described method is used by using a resin whose intrinsic viscosity is increased by solid-phase polymerization, or a heat-treated resin is used to form a film. It is preferable at the point which can suppress subsequent oligomer precipitation.

Hereinafter, the manufacturing method of the film of this invention is demonstrated using FIGS.
First, polyester resin chips are mixed as necessary, and then the moisture in the chips is removed by the vacuum dryer 1 shown in FIG. Thereafter, it is stored in the raw material hopper 2 and melted and extruded by the extruder 3. Thereafter, the filter 4 is used for filtration.
In the biaxially oriented polyester film of the present invention, in order to suppress the surface loss of the molding layer, it is preferable that the foreign matter inside the film is 2 or less per 100 cm ² of 100 μm or more. It is preferably not included.
In order to obtain such a film, it is necessary to use a filter with a filtration accuracy of 1 to 20 μm, and a filter with an absolute filtration accuracy of 3 to 10 μm is used in order to suppress the filtration life, coarse protrusion, and internal foreign matter. More preferably.

The center line roughness SRa on the surface of the biaxially oriented polyester film of the present invention is preferably 10 nm or more and 40 nm or less, and more preferably 5 to 35 nm. With such a range centerline roughness, it is possible to control the transport properties of the film (the friction characteristics of the roll), easily controlled by the area of the charge transfer marks 100 cm ² per 5 cm ² or more 30 cm ² or less .

  In order to make the center line roughness of the film surface within the above range, it is preferable to add a lubricant to the film, and it is preferable to use particles having an average particle size of 0.01 μm or more and 8 μm or less. Further, the content of the lubricant particles in the film is preferably 0.001 wt% or more and 5 wt% or less with respect to the entire film. If it exceeds 5% by weight, SRa exceeds 40 nm, and if it is less than 0.001% by weight, SRa is less than 10 nm. The molten resin after filtration is taken out from the slit-shaped die 5 in FIG. 1 and formed into a sheet shape. This sheet-like product is wound around a casting drum 6 having a surface temperature of 20 to 50 ° C. and cooled and solidified to obtain an unstretched (unoriented) film.

  This unstretched film is heated to 70 to 130 ° C. in the longitudinal stretching machine 7 of FIG. 1, and is stretched in one or more stages so that the magnification becomes 2.5 to 5 times due to the peripheral speed difference between the rolls. The film is stretched in the direction to obtain a uniaxially stretched (uniaxially oriented) film.

  The uniaxially stretched film stretched in the longitudinal direction is stretched 3 to 6 times in the width direction at 80 ° C. to 120 ° C. with a transverse stretcher (stenter) 8 in FIG. 1, and biaxially stretched (biaxial orientation). A film. After extending | stretching, after heat-processing for 1 to 20 seconds at 180 to 250 degreeC, it shrinks 0 to 10% in the width direction at the temperature 0 to 150 degreeC lower than heat processing temperature.

  When the biaxially oriented polyester film of the present invention is used as a release film, the molding member raw material is applied onto the biaxially oriented polyester film, and then dried in an oven to form a molded layer. However, for the purpose of preventing heat wrinkles from being generated in the film of the present invention in the oven and deforming the molding layer, the shrinkage ratio of the film of the present invention after heat treatment at 150 ° C. for 30 minutes (JIS C-2151 or (According to ASTM D-1204) is 1.2 to 1.7% in the longitudinal direction (MD: Machine Direction) with respect to the film conveying direction, and 0.0 to 0 in the width direction (TD: Transverse Direction). .7% is preferable.

  In order to obtain a heat shrinkage rate in the above range, the film is heated to 80 to 100 ° C., stretched in the longitudinal direction in one step so that the magnification is 3 to 4 times due to the peripheral speed difference between the rolls, and stretched in the longitudinal direction. The stretched film was stretched in the width direction by 3 to 4.5 times at 90 ° C. to 110 ° C. in the transverse stretching machine 8 of FIG. 1, and then heat treated at 210 ° C. to 240 ° C. for 5 to 20 seconds. Then, it is preferable to shrink 3 to 8% in the width direction at a temperature lower by 10 to 100 ° C. than the heat treatment temperature. Furthermore, when the biaxially oriented polyester film of the present invention is used as a release film for electrical insulation, it is heated by a build-up process. If the expansion / contraction difference from the insulating resin is large, wrinkles and tarmi occur in the build-up process. In order not to generate such wrinkles and slack, the shrinkage ratio of the film after being heated at 150 degrees for 30 minutes is 1.2 to 1.5% in MD and 0.1 to 0.5% in TD. preferable.

  In order to obtain a heat shrinkage rate in the above range, the film is heated to 80 to 100 ° C., stretched in the longitudinal direction in one step so that the magnification is 3 to 4 times due to the peripheral speed difference between the rolls, and stretched in the longitudinal direction. The stretched film was stretched in the width direction 3 to 4.5 times at 90 ° C. to 110 ° C. with the transverse stretching machine 8 of FIG. 1, and then heat treated at 220 ° C. to 240 ° C. for 5 to 20 seconds. Then, it is preferable to shrink 4 to 7% in the width direction at a temperature lower by 10 to 100 ° C. than the heat treatment temperature.

  The film stretched in the width direction is cooled by the cross transfer device 9 in FIG.

  The intermediate product 10 is slit and wound in an appropriate width in the slitting process shown in FIGS. 2 and 3 to obtain the biaxially oriented polyester film of the present invention.

  In the slitting process, the film is being scraped by the difference in draw between the film being transported and the slitter transport roll (11a, 11b, 11c, 11d, 11e, 11f, 11g in FIG. 2, 11h, 11i, 11j, 11k in FIG. 3) A scratch or a charged pattern is formed along the pattern shape on the surface.

Moreover, in this invention, it is preferable that a half or more roll is a rubber roll among several slitter conveyance rolls used for the said slitter conveyance. More preferably, all the slitter conveyance rolls in the slitting process are rubber rolls. Here, the rubber roll refers to a roll in which at least the surface of the roll is covered with rubber (including a roll whose whole roll is rubber). By using such a rubber roll, the area of the charge transfer mark on the film can be 5 cm ² or more and 30 cm ² or less per 100 cm ² . It is also effective in suppressing the meandering of the film in the slit. The rubber used for the rubber roll is at least one rubber selected from nitrile rubber (a copolymer of acrylonitrile and butadiene), chloroprene rubber (polychloroprene), ethylene / propylene / diene rubber, and chlorosulfonated polyethylene rubber. It is preferable that More preferably, chloroprene rubber is used. Chloroprene rubber is preferable in that it can obtain an appropriate grip force, can control the charging characteristics of the film, and can effectively perform a slip treatment described later.

In addition, in order to appropriately control the frictional charge generated between the slitter transport roll and the film, carbon is contained in the rubber used in the slitter transport roll to give conductivity, and the conductivity of the surface of the slitter transport roll Resistance 1 × 10 ³
It is preferable to adjust to ˜1 × 10 ⁸ Ω. The surface of the rubber roll is digged at an angle in order to exclude air that has entered between the film and the roll during conveyance (this processing is hereinafter referred to as “mesh processing”. The applied rubber roll is preferably referred to as a “diamond cut roll”. The meshed grooves may be applied in an X shape as shown in FIG. 4 with a width of 1 to 2 mm, a depth of 1 to 1.5 mm, and an angle of 20 to 45 ° with respect to the roll width direction. preferable. The portion 16 of the roll surface remaining when the groove 17 is provided becomes a rhombus or a square. When transported by this roll, the surface of the rubber roll surface in contact with the film becomes an aggregate of rhombus or square (FIG. 4).

The diamond cut roll subjected to the mesh processing can grip the film intensively on a rhombus or square surface, and can have a uniform grip force in the circumferential direction of the roll. Further, a charging trace having a certain pattern is generated along the surface shape (for example, rhombus) of the roll by the contact-peeling process between the slitter transport roll and the film or by charging by rubbing. This charge pattern, as described later, the winding before the discharger 13a, can be removed by 13b, not completely removed, charged as the area of the charge transfer marks is 100 cm ² per 30 cm ² or less It is preferable to maintain the state. Further, if a minute draw difference is generated between the slitter transport roll and the film, scratches may occur. The scratches in the process are accompanied by deformation to such an extent that the surface properties of the molded member are not impaired. However, in the subsequent processing process, oligomers are likely to be precipitated from the site where the scratches are generated, which affects the peeling characteristics and is deposited. The oligomer is transferred to the molded member and becomes a defect.

For this reason, it is preferable that the scratches on the film surface generated between the slitter transport roll and the film have a length of 1 mm or more, preferably 100 or less per 100 cm ² , and more preferably not contain substantially.

  The rubber roll used for the slitter conveyance roll is preferably subjected to a slip treatment. This is because the charging state of the film in the transporting process can be appropriately adjusted by the slip treatment. The slip treatment includes (1) treatment to deteriorate the rubber surface by UV (ultraviolet light) irradiation, (2) treatment to chemically roughen and deteriorate the rubber surface using a chemical solution, and (3) easy slip material ( For example, a process of coating Teflon (registered trademark), etc. can be mentioned. In the case of the process (3), the rubber composition tends to bleed out after the process, or foreign substances are mixed into the product by scraping the lubricant. Sometimes. Therefore, the UV irradiation process of (1) is desirable for the slip process. However, if the sliding treatment is performed too much, the grip force of the roll is reduced, and the peripheral speed difference between the roll and the film is likely to be generated and the film is easily charged. Therefore, the static friction coefficient μs of the roll surface is 0.5 to 1. 0 or less is preferable.

  The drive system of the slitter transport roll includes the pulley drive system and the individual drive motor system, but the individual drive motor system can finely adjust the peripheral speed difference between the rolls, thus controlling the charging while suppressing the generation of scratches. This is preferable because it can be performed. The rotation speed of the roll is preferably 100 m / min to 400 m / min, and more preferably 150 m / min to 300 m / min in order to control the charging characteristics.

The speed ratio of each slitter transport roll from the unwinding of the intermediate product 10 to the winding of the product rolls 15a and 15b is slit cutting in the slitter transport rolls (11a to 11g) existing before the film slit by the cutting device 12. The roll immediately before is referred to as a reference (referred to as a reference roll, which corresponds to an 11 g roll in the slitter of FIG. 2), and is preferably controlled at a speed of -0.02 ± 0.02%. In addition, in the slitter transport rolls (11h, 11i, 11j) existing after the film slit, the speed of the roll (11h) immediately after the slit is controlled at the reference roll (11g) ratio + 0.15 ± 0.02%, From the slitter transport roll, it is preferable to increase the speed by 0.03% from the previous slitter transport roll. By setting the speed ratio of the slitter transport roll within such a range, desired charging characteristics can be imparted to the film while maintaining good transportability.
The product rolls 15a and 15b of the biaxially oriented polyester film of the present invention can be collected by slitting the intermediate product 10 with a cutting device 12 to a desired width and winding it. It is preferable to wind up while excluding air with the contact rolls 14a and 14b.

  The surface of the contact roll is preferably made of rubber. The rubber material can be selected from nitrile rubber (a copolymer of acrylonitrile and butadiene), chloroprene (polychloroprene), ethylene / propylene / diene rubber, and chlorosulfonated polyethylene rubber.

It is preferable that there is no groove for eliminating air on the contact roll surface.
This is because, if the contact roll has a groove for removing air, scratches will occur when a difference in peripheral speed occurs.

  The contact roll does not have its own drive mechanism, and its rotational speed depends on the outer peripheral speed of the product roll of the biaxially oriented polyester film of the present invention. If the roll is not evenly contacted, a difference in peripheral speed between the contact roll and the product roll tends to occur.

Moreover, the static friction coefficient of the contact roll is preferably 0.3 to 1.5 in order to prevent peeling electrification and to achieve both gripping force. When the static friction coefficient of the contact roll is less than 0.3, the gripping force is lost and the slipping causes a large frictional charge. When the contact roll exceeds 1.5, the gripping force is increased, and peeling electrification is likely to occur.
The contact roll sliding treatment includes (1) treatment for deteriorating the rubber surface by UV irradiation, (2) treatment for chemically roughening and degrading the rubber surface using a chemical solution, and (3) using a chemical solution. There is a method in which after the rubber surface is chemically deteriorated, the rubber surface is polished to homogenize the surface.

  The diameter of the contact roll is preferably in the range of 50 mm or more and 180 mm or less in view of rigidity and air evacuation property, but more preferably 90 mm or more and 150 mm or less.

  The roll potential after winding is preferably ± 5 kV or less because it has a correlation with the charged state of the film surface.

  In order to set the roll potential in such a range, it is preferable to perform static elimination with the static elimination 13a and 13b. The neutralization is generally performed by neutralizing the charge state on the film surface by applying positive and negative ion currents to one surface of the film or alternately to the surface of the film. Polyester films are often negatively charged, but taking into account disturbances in the slit process, it is preferable to apply positive and negative ions to the film surface in an alternating current manner. At this time, the distance between the film and the static elimination electrode is preferably 100 to 150 mm, and the output is preferably 9 kV or less. The biaxially oriented polyester film of the present invention may be a laminated film such as a single layer, a co-extruded two-layer laminated film, or a three-layer laminated film. Therefore, when adding particles only to the film surface layer, a two-layer laminated film and a three-layer laminated film having a high degree of freedom in particle mixing ratio are preferable. When the biaxially oriented polyester film of the present invention is used as a mold release, the thickness depends on the thickness of the molded member, the mechanical suitability such as the processing temperature and the tensile strength against the processing tension, the cost, and the environmental load at the time of disposal. Although it is selected depending on the element for reduction, it is preferably 15 μm or more and 188 μm or less, more preferably 25 μm or more and 50 μm or less.

Next, embodiments of the present invention will be described based on examples.
The characteristic value measurement method and evaluation method defined in the present invention will be described below.

(1) Hydroxyl solvent “Isopar H” manufactured by ExxonMobil as an agent A for electrification transfer mark area on the film surface, and Savin Toner manufactured by Savin as a B agent (Savin Corporation, Savin Black Dispersant: For Savin V-35, 7300, 7350, 7450 copiers), B agent dissolved at a ratio of 0.5 liter in 18 liters of agent A was sprayed on the film surface of 10 cm × 10 cm by spraying and left for 10 minutes. The area of the charging pattern (the part to which the toner is attached) that appears on the surface is measured, and the area of the charged transfer mark per 100 cm ² is calculated.

(2) Abrasion on the surface of the film After the biaxially oriented polyester film of the present invention was cut into a size of 10 cm × 10 cm, aluminum was vapor-deposited to a thickness of 50 nm using a vacuum vapor deposition machine, and then Cadonicalite manufactured by Sanyo Electric Co., Ltd. With “NL S-1”, scratches were marked while illuminating at an angle of 10 to 50 degrees with respect to the film surface. Thereafter, it was observed with a stereomicroscope, and the number of scratches having a length of 1 mm or more was counted as the number of scratches.

(3) Epoxy peeling properties An epoxy resin (molding member raw material) used for forming an electrical insulating sheet on the film of the present invention is applied by a die coater so that the thickness after drying is 40 μm, and is 120 ° C. for 5 minutes. The molded layer was formed by drying. Then, in order to transfer the molding layer (epoxy layer) to the printed wiring board in a state where the molded product of the epoxy resin is supported on the film of the present invention, it is matched with the printed wiring board having a thickness of 0.3 mm, and 120 ° C. with a vacuum laminator And laminating under conditions of pressure 0.5 MPa. After lamination, the film was peeled off to obtain a molded member for electrical insulation. The state of the film surface after peeling and the surface state of the molding member (epoxy molding) were observed.
a. As a result of observing the surface state of the film after peeling, a film in which no epoxy resin remained on the film surface was evaluated as ◯ (good), and a film that remained was evaluated as x (defective).
b. As a result of observing the surface condition of the epoxy molded product after peeling, the surface of the epoxy molded product is smooth and has no defects (good), dents due to coating repelling, foreign matter adhesion, and epoxy adhesion to the film surface A state where there is a defect on the surface, such as a case where there is a depression due to, was defined as x (defect).
In addition, it can use especially suitably as a release film for electrical insulation, so that the said characteristic is a favorable film. (4) Centerline roughness of film surface (SRa)
Measured using a three-dimensional fine surface shape measuring instrument (ET-30HR manufactured by Kosaka Mfg. Co., Ltd.), the arithmetic average roughness SRa value was determined from the obtained film surface profile curve according to JIS B0601-1994. The measurement conditions are as follows.
X-direction measurement length: 0.5 mm, X-direction feed speed: 0.1 mm / second Y-direction feed pitch: 5 μm, Y-direction line number: 40 lines.
Cut-off: 0.25 mm.
Stylus pressure: 0.02N. (5) Measured with a conductive resistance insulation resistance meter (Digital Megohm Hitester 3454-11 manufactured by Hioki Electric Co., Ltd.) of a slitter transport roll. The measurement position was a central portion on the surface of the transport roll, terminals were arranged at 100 mm intervals in the width direction, and the measurement conditions were a current of 1 mA and a voltage of 250V.

(5) Product roll potential Product roll wound from an intermediate product with a winding length of 7500m is used as a sample roll, and the digital electrostatic potential measuring device MODEL KSD-0103 (manufactured by Kasuga Electric Co., Ltd.) The measurement is performed for 5 seconds at the center of the sample roll width direction at a distance of 50 mm, and the value having the highest display frequency is employed. (7) Static Friction Coefficient of Slitter Transport Roll A friction coefficient measuring strip 19 (created by “Lumirror” 125S10) is held on the slitter transport roll as shown in FIG. Next, as shown in FIGS. 6 and 7, a weight 21 is attached to one end of the strip. The load due to the weight is 2N. A digital spring balance (Digital Force Gauge DDPRS2T manufactured by IMADA) 22 is connected to the strip hole 20 using a hook. After waiting for the shake of the weight to stop, the digital spring balance was pulled horizontally, and the force F ′ when the strip started to move was measured. The force F ′ was measured three times at a total of three points at both ends and the center of the slitter transport roll, and the average value of all measurements was taken as F.
The static friction coefficient was calculated | required by following Formula.
Coefficient of static friction = 2 / π × (Logn (F / F0))
π: Circumference ratio Logn: natural logarithm F: force when the strip starts to move after the digital spring balance is pulled horizontally (N)
F0: Load due to weight (N)
Examples 1-3, Comparative Example 1, Comparative Example 2, Comparative Example 3
A raw material chip obtained by adding and mixing silicon oxide having an average particle diameter of 2 μm to 0.5 wt% using a chip of polyethylene terephthalate (extreme viscosity 0.65) substantially free of particles polymerized by a conventional method, After vacuum drying (5 Torr) at 180 ° C. for 7 hours, the mixture was supplied to an extruder and melted at 280 ° C.

  After the molten polymer is filtered through a filter having an absolute filtration accuracy of 5 μm, it is extruded into a sheet form from a die having a slit width of 5.0 μm, wound around a casting drum having a surface temperature of 25 ° C. using an electrostatic application casting method, and solidified by cooling. An unstretched film was made. This unstretched film was stretched 3.0 times in the longitudinal direction at 85 ° C. Next, using a stenter, the film was stretched 4.0 times in the width direction at 105 ° C., heat-set at 230 ° C., relaxed by 6.9% in the width direction at 150 ° C., and then wound up to a thickness of 38 μm. An intermediate product of biaxially oriented polyester film was obtained.

  The obtained intermediate product was guided to the slit process shown in FIGS. 2 and 3 and slitted. Table 1 shows the material and the like of the slitter transport roll used in the slitting process, and Table 2 shows the static elimination voltage of the static eliminator (AC type). Table 2 shows various characteristics of the biaxially oriented polyester film and roll obtained through the slitting process.

  From Table 1, the biaxially oriented polyester film of Examples 1-3 shows the outstanding characteristic.

  On the other hand, in Comparative Example 1, epoxy resin coating spots occurred in the epoxy peeling property test, and local omission occurred. Moreover, there was an epoxy residue on the film after the epoxy peeling, and the surface state of the epoxy resin was deteriorated.

  The comparative example 2 had strong resistance at the time of film peeling of an epoxy peeling characteristic test, and the epoxy resin adhered to the film in the form of horizontal stripes.

  In Comparative Example 3, application spots occurred in the epoxy resin property test, and local omission occurred. Further, when the film was peeled off in the epoxy resin property test, the epoxy resin adhered to the film as a residue in such a manner that the pattern on the roll surface of the slitter was transferred, and the surface condition of the epoxy resin was deteriorated.

  The mesh processing in Table 1 is processing in which a groove is provided so as to have an X shape with a width of 1.5 mm, a depth of 0.8 mm, and an angle of 20 ° with respect to the roll width direction.

The figure which illustrated the whole structure of the film manufacturing equipment The figure which illustrated the outline of the composition of a slit process The enlarged view of the A section of FIG. Bird's-eye view illustrating the surface shape of a diamond cut roll Sectional view along line B1-B2 in FIG. Illustration of strip for measuring coefficient of static friction Explanation of static friction coefficient measurement method (cross-sectional view)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vacuum dryer 2 Raw material hopper 3 Extruder 4 Filter 5 Die 6 Casting drum 7 Longitudinal stretching machine 8 Lateral stretching machine 9 Cross conveyance apparatus 10 Intermediate product 11a-11k Slitter conveyance roll 12 Cutting apparatus 13a, 13b Neutralizer 14a, 14b Contact Roll 15a, 15b Product roll of biaxially oriented polyester film of the present invention 16 Roll surface of slitter transport roll 17 Roll groove portion of slitter transport roll 18 Film 19 Strip for measuring static friction coefficient 20 Hole for attaching hook of digital spring balance 21 Weight 22 Digital spring balance 23 Slitter transport roll

  Since it is a biaxially oriented polyester film having appropriate adhesion and release properties with various coating materials such as molding member raw materials, it is useful for those applications.

Claims (4)

A biaxially oriented polyester film having an area of a charge transfer mark on the film surface of 5 cm ² or more and 30 cm ² or less per 100 cm ² . The biaxially oriented polyester film according to claim 1, which is used as a release film. The biaxially oriented polyester film according to claim 2, which is used as a release film for electrical insulation. More than half of the plurality of slitter transport rolls used for the slitter transport are rubber rolls, and the rubber used for the rubber rolls is selected from nitrile rubber, chloroprene rubber, ethylene / propylene / diene rubber and chlorosulfonated polyethylene rubber. And a slitter transport roll having a slitting transport roll surface having a mesh processing and a static friction coefficient μs of 0.5 to 1.0 on the surface of the slitter transport roll. The manufacturing method of the biaxially-oriented polyester film of Claims 1-3 which passes through a slitter process.

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