JP7205748B2 - resin film - Google Patents

Description

The present invention is used in applications requiring extremely high dimensional stability, such as base films used in ultra-high-density recording media exceeding 10 Tb. The present invention relates to a resin film which is easy to adjust and excellent in workability for magnetic recording media.

2. Description of the Related Art In recent years, as the amount of data that needs to be handled in computer systems and the like has increased, there has been a demand for a significant increase in the recording capacity of magnetic recording media. Conventionally, efforts have been made to improve the dimensional stability of substrates used in magnetic recording media (Reference 1), but improvements in substrate dimensional stability with inexpensive materials are reaching their limits. In addition, by adjusting the tape tension to match the tape width during data recording and data playback, the track position during recording is within the range of the playback head. Proposals have also been made to reduce this (references 2-4). These techniques change the longitudinal dimension of the tape by changing the tension in the longitudinal direction of the tape. The purpose is to converge the tape width during playback within the allowable range. However, the adjustment range of the tape width by tape tension requires a large tension change when using a conventional high-rigidity magnetic recording medium substrate. In recent years, the tension of tape playback devices for high-density recording has been set to be as small as possible in order to suppress irreversible changes due to creep deformation of magnetic recording media as much as possible. However, the tape width adjustment range is limited to a very small area, and it becomes difficult to greatly improve the recording density by increasing the number of tracks. On the other hand, using a low-rigidity base material makes it easier to adjust the tape width by adjusting the tape tension. When a high tension is applied, the base material itself is stretched and easily buckled, which makes it impossible to obtain a good magnetic recording medium.

Japanese Patent Application Laid-Open No. 2010-31116 JP 2005-285196 A JP-A-2005-285261 JP 2006-099919 A

The object of the present invention is to realize a large dimensional change with a small change in tension by adjusting the tape tension as a means for realizing a large improvement in track density required for ultra-high density magnetic recording media. It is an object of the present invention to provide a resin film for a magnetic recording medium base material, which can be used as a magnetic recording medium, and which is excellent in processing process suitability for a magnetic recording medium.

As a result of intensive research by the inventors of the present invention to solve the above-mentioned problems, the present inventors have found that by making it possible to achieve both ease of width control by tape tension, which has been difficult in the past, and suitability for processing to magnetic recording media, the present invention has been achieved. arrived at the invention.

Thus, according to the present invention, the Young's modulus in the longitudinal direction of the film is 1 GPa or more and 6 GPa or less, the film thickness is 1 μm or more and 4.5 μm or less, and the product of the Young's modulus in the longitudinal direction and the thickness is 5 GPa·μm or more and 20 GPa·μm or less. and a dimensional change in the longitudinal direction of the film is −2% or more and +2% or less when the temperature is raised from 30° C. to 110° C. under a load of 2 kg/mm ² in the longitudinal direction.

The resin film of the present invention realizes high-density recording by facilitating adjustment of the tape width by tape tension in a base film or the like used for an ultra-high-density recording medium of 10 Tb or more, and is suitable for magnetic recording media. It is possible to provide data storage that does not cause wrinkles during processing.

1 is a perspective view of a dimension measuring device used in the present invention; FIG. It is a schematic diagram which shows the curvature radius of the mounting surface in FIG.

The present invention will be described in detail below. For convenience of explanation, the film-forming direction of the film may be referred to as the machine axis direction, the longitudinal direction, the longitudinal direction, and the MD direction, and the direction orthogonal to the film-forming direction and the thickness direction may be referred to as the width direction, the lateral direction, and the direction perpendicular to the thickness direction. It may be called TD direction.

The resin film of the present invention has a Young's modulus in the longitudinal direction of the film of 1 GPa or more and 6 GPa or less. If the Young's modulus is less than the lower limit, it is very difficult to handle a thin film. A large tension change must be applied. A preferable lower limit of Young's modulus in the longitudinal direction is 1.5 GPa or more, further 2 GPa or more, particularly 2.5 GPa or more, and a preferable upper limit is 5.5 GPa or less, further 5 GPa or less, particularly 4.5 GPa or less.

The resin film of the present invention has a thickness of 1 μm or more and 4.5 μm or less. If the thickness is less than the lower limit, the handling becomes very difficult, and the film tends to break during film formation, which is not suitable. If the thickness exceeds the upper limit, it becomes necessary to give a greater change in tension when adjusting the tape tension of a reproducing apparatus to control the dimension in the width direction when the magnetic recording medium is used. A more preferable lower limit of the thickness is 1.5 μm or more, further 2 μm or more, and a preferable upper limit is 4 μm or less, furthermore 3.5 μm or less.

The resin film of the present invention has a value of the product of Young's modulus in the longitudinal direction and thickness of 5 GPa·μm or more and 20 GPa·μm or less. If this value is less than the lower limit, it is very difficult to handle, and if this value exceeds the upper limit, the tape tension of the reproducing device is adjusted to control the dimension in the width direction when used as a magnetic recording medium. At that time, a larger tension change must be applied. More preferably, the lower limit of the value of the product of Young's modulus in the longitudinal direction and the thickness is 8 GPa·μm or more, furthermore 10 GPa·μm or more, and the preferable upper limit is 18 GPa·μm or less, furthermore 16 GPa·μm or less.

Furthermore, the resin film of the present invention exhibits a dimensional change of -2% or more and +2% or less in the longitudinal direction when the film is heated from 30°C to 110°C under a load of ² kg/mm2 in the longitudinal direction. If the amount of dimensional change in the longitudinal direction is less than the lower limit, transfer from the back surface to the magnetic layer surface tends to occur due to tight winding in the roll state during processing to the magnetic recording medium, adversely affecting the electromagnetic conversion characteristics, which are important characteristics. give. On the other hand, if the upper limit is exceeded, the magnetic paint tends to stretch in the longitudinal direction when applied, and wrinkles are generated due to the buckling phenomenon. More preferably, the lower limit of the dimensional change in the longitudinal direction of the film is −1% or more, further −0.5% or more, particularly 0% or more, and the upper limit is +1.8% or less, further +1.6% or less, particularly +1. 4% or less.

The resin for forming the resin film of the present invention is not particularly limited as long as it can employ a known resin and can be formed into a flat film. Specific resins include polyester, polysulfone, polyamide, polyether, polyketone, polyacryl, polycarbonate, polyacetal, polystyrene, polyamideimide, polyarylate, polyolefin, polyfluoropolymer, polyurethane, polyarylsulfone, polyethersulfone, and polyarylene. Sulfur, polyvinyl chloride, polyetherimide, tetrafluoroethylene, and polyetherketone may be mentioned, and these may be copolymerized or used in the form of mixtures. Among these, aromatic polyesters, polyetherketones, polyarylene sulfides, polyolefins, aliphatic polyamides, and semi-aromatic polyamides are particularly preferred. Each resin will be described in further detail below.

First, as the polyester in the present invention, a polyester having dibasic acid and glycol as constituent components is preferably mentioned. For example, aromatic dibasic acids include terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenyletherdicarboxylic acid, diphenylketonedicarboxylic acid, phenylindanedicarboxylic acid, sodium sulfoisophthalic acid, and dibromoterephthalic acid. , 4,4′-diphenyldicarboxylic acid, 6,6′-(ethylenedioxy)di-2-naphthoic acid and the like can be used. As the alicyclic dibasic acid, oxalic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, dimer acid and the like can be used. As the glycol, aliphatic diols such as ethylene glycol, propylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, and diethylene glycol can be used. hydroxydiphenyl)propane, 2,2-bis(4-hydroxyethoxyphenyl)propane, bis(4-hydroxyphenyl)sulfone, hydroquinone, etc., and alicyclic diols such as cyclohexanedimethanol, cyclohexanediol, etc. can be used.

Furthermore, the polyester in the present invention is preferably substantially linear from the viewpoint of forming a film, and within the range of being substantially linear, a trifunctional or higher polyfunctional compound such as glycerin, trimethylolpropane, penta Erythritol, trimetic acid, trimesic acid, pyromellitic acid, tricarballylic acid, gallic acid and the like may be copolymerized, and monofunctional compounds such as o-benzoylbenzoic acid and naphthoic acid may be added and reacted. Polyethers such as polyethylene glycol, polyethers such as polytetramethylene glycol, and aliphatic polyesters such as polycaprolactone may also be copolymerized.

The polyester in the present invention may be used as a composition in which two or more types are blended. For example, if polyester accounts for 50% by mass or more, it may be blended with a material other than polyester.

The intrinsic viscosity of the polyester used in the present invention (measured at 35° C. in orthochlorophenol) is preferably 0.55 dl/ g, a more preferred lower limit is 0.6 dl/g, and a most preferred lower limit is 0.7 dl/g. If the intrinsic viscosity is lower than 0.55 dl/g, the melt-kneadability with polyetherimide is lowered. The upper limit is preferably 2 dl/g, more preferably 1.4 dl/g, and most preferably 1.0 dl/g. When the intrinsic viscosity exceeds 2.0 dl/g, the load during extrusion increases, decomposition due to heat generated by shearing occurs, and coarse protrusions may be formed. In particular, when other resins such as polyetherimide described later are blended, the intrinsic viscosity is preferably at least the lower limit from the viewpoint of melt-kneadability.

When a polyester film is selected as the resin film of the present invention, it is also one of preferred embodiments that it contains polyetherimide. Polyetherimide is a polymer containing repeating units of aliphatic, alicyclic or aromatic ether units and cyclic imide groups, and is not particularly limited as long as it has melt moldability. For example, U.S. Pat. No. 4,141,927, U.S. Pat. No. 2,622,678, U.S. Pat. No. 2,606,912, U.S. Pat. Japanese Patent No. 2598536, Japanese Patent No. 2599171, Japanese Patent Application Laid-Open No. 9-48852, Japanese Patent No. 2565556, Japanese Patent No. 2564636, Japanese Patent No. 2564637, Japanese Patent No. 2563548, Japanese Patent No. 2563547, Patent Polymers described in Japanese Patent No. 2,558,341, Japanese Patent No. 2,558,339, and Japanese Patent No. 2,834,580, etc. can be mentioned. As long as the effects of the present invention are not impaired, the main chain of the polyetherimide contains structural units other than cyclic imide and ether units, such as aromatic, aliphatic, and alicyclic ester units, oxycarbonyl units, and the like. may have been

In the case of the polyester film containing the above polyetherimide, a polyetherimide having a glass transition temperature of 350° C. or less, more preferably 250° C. or less is preferred, and 2,2-bis[4-(2,3-dicarboxyphenoxy ) A condensate of phenyl]propane dianhydride and m-phenylenediamine or p-phenylenediamine is most preferred from the viewpoints of compatibility with polyester, cost, melt moldability and the like. This polyetherimide is known from the "Ultem® 1000 or 5000 series" manufactured by SABIC.

The content of polyetherimide is preferably 0.5% by mass or more and 10% by mass or less based on the weight of the resin composition of polyester and polyetherimide. In the resin film of the present invention, the content of polyetherimide is preferably at least the above lower limit in order to exhibit the effect of containing polyetherimide in the polyester film, and the polyetherimide serves as the core. In order to suppress internal foreign matter, the content of polyetherimide is preferably equal to or less than the upper limit.

In the case of the polyester film containing the polyetherimide, it is preferable that the polyetherimide is dispersed in the film with an average dispersion diameter of 1 nm or more and 50 nm or less. If the average dispersed diameter is within this range, variations in strength, dimensional stability, and dimensional change rate are suppressed, making it possible to obtain a resin film with significantly improved properties. When the average dispersed diameter is larger than 50 nm, the restraining force of the polyimide on the polyester molecules is lowered, so that the glass transition point is lowered, the thermal dimensional stability is lowered, and the variation in the dimensional change rate tends to increase. Furthermore, it causes an increase in the above-described undulation. In order to obtain better physical properties, the average dispersion diameter is preferably 20 nm or less, and most preferably 10 nm or less for controlling the amplitude intensity (undulation). The lower limit is preferably 1 nm or more.

The method of dispersing the polyetherimide in the polyester with an average dispersion diameter of 1 nm or more and 50 nm or less (or the method of making it compatible and containing) is not particularly limited, but the polyester and the polyetherimide are put into an extruder, ( 1) A screw shear rate of 30 seconds ^-1 or more and less than 300 seconds ^-1 , (2) an extrusion temperature of 280°C or more and 320°C or less, and (3) a polymer discharge time of 30 seconds or more and 10 minutes or less. Then, it is preferable to mold the resin composition. Regarding (1) above, the screw shear rate of the extruder (=πDN/h, D: screw diameter, N: screw rotation speed, h: groove depth of screw metering section) is 50 seconds ^-1 or more, 250 seconds ^- It is more preferably less than ¹ , and preferably set to 90 sec ^-1 or more and less than 200 sec ^-1 from the viewpoint of inhibiting thermal decomposition of polyester and compatibilizing polyester and polyetherimide. The average dispersion diameter of the polyetherimide in the film is preferably 3 nm or more and less than 5 nm.

From the viewpoint of promoting fine dispersion and compatibilization of the polyester or polyetherimide and reducing coarse dispersion, it is preferable to use various mixing screws having a screw length-to-diameter ratio of 20 or more, preferably 25 or more. . Mixing type screws are suitable for kneading discs, rotor types, and the like. The extruder may be either a single-screw kneading type or a twin-screw kneading type, but it is effective to use a high-shear, low-heat-generating type screw, and the twin-screw type is preferably used. In the present invention, the extrusion temperature is preferably 290° C. or higher and 320° C. or lower from the viewpoint of compatibilization of polyester and polyetherimide and suppression of thermal decomposition of polyester. Further, the polymer ejection time is more preferably 1.5 minutes or more and 6 minutes or less, and most preferably 2 minutes or more and 5 minutes or less. The discharge time can be appropriately changed by changing the operating conditions of the feeder and gear pump and the screw rotation speed of the extruder. The polymer discharge time is the value V/Q obtained by dividing the total volume V of the extrusion process including the extruder, tube, filter and die by the polymer discharge rate Q. The discharge time can be appropriately changed by changing the operating conditions of the feeder and gear pump and the screw rotation speed of the extruder. Further, in the present application, in order to control the amplitude intensity (undulation) in the longitudinal direction and the width direction in the wavelength range of 100 μm or more and 1,000 μm or less by frequency analysis of the surface roughness on the A side to a desired value, the above extrusion It is also effective to optimize the natural frequency generated in each step of the extrusion process including the machine, gear pump, tube, filter, and mouthpiece. Specifically, the natural frequency in each process is measured, and control is performed so that the frequency does not overlap between processes.

Furthermore, in the method of incorporating polyetherimide into polyester, a raw material obtained by collecting a biaxially oriented polyester film formed by using the resin composition in which polyetherimide is compatible with polyester obtained by the above, Since the polyetherimide is evenly dispersed in the polyester, it can be preferably used. Also in this case, the content of polyetherimide in the recovered raw material is preferably 0.5% by mass or more and 10% by mass or less. At this time, the recovered raw material is obtained by crushing the film with a grinder (crusher) to obtain flakes, pressing the flakes if necessary, melting, removing foreign matter with a filter having an opening of 10 to 50 μm, It is preferable to discharge and cool the resin from the die to obtain a resin (gut) solidified into a continuous thick thread, and then cut the gut with a rotary blade to obtain the recovered raw material.

Next, the polyether ketone in the present invention includes those containing structures represented by the following formulas (1) and (2) as constitutional units, and may contain a monomer unit having a single structure or another structure. .

Examples of monomer units having other structures are as follows.

In the above structural units, A is a direct bond, oxygen, —CO—, —SO ₂ — or a divalent lower aliphatic hydrocarbon group, Q and Q′ may be the same or different, and — is CO- or -SO2-, and n is 0 or 1; These polymers are described in JP-B-60-32642, JP-B-61-10486, JP-A-57-137116, and the like.

In the present invention, the polyether ketone resin preferably has an aspect including the above formula (2) (hereinafter, such an aspect is referred to as a thermoplastic polyether ether ketone resin). When the thermoplastic polyetherketone resin is in an embodiment containing the above formula (2), the content of the unit represented by the above formula (2) is preferably 60 mass based on the mass of the thermoplastic polyetherketone resin. % or more, more preferably 80 mass % or more, particularly preferably 90 mass % or more.

Furthermore, the polyolefin resin in the present invention is not particularly limited, and polyethylene, polypropylene, cycloolefin, polystyrene and the like can be exemplified. Among these, polypropylene and polystyrene, particularly a specific polypropylene and a polystyrene having a syndiotactic structure, which will be described later, are preferred from the viewpoint of obtaining suitable physical properties and securing heat resistance by stretching appropriately.

The polypropylene in the present invention preferably has a cold xylene soluble portion (hereinafter referred to as CXS) of 4% by mass or less and a mesopentad fraction of 0.95 or more. If these conditions are not satisfied, the film forming stability may be poor, or voids may be formed in the film when producing a biaxially oriented film, resulting in a large decrease in dimensional stability.

Here, the cold xylene soluble portion (CXS) refers to the polypropylene component dissolved in xylene when the film is completely dissolved in xylene at 135 ° C. and then precipitated at 20 ° C. It is thought that this corresponds to a component that is difficult to crystallize because of its low properties, low molecular weight, and the like. If a large amount of such components are contained in the resin, problems such as poor thermal dimensional stability of the film may occur. Therefore, CXS is preferably 4% by mass or less, more preferably 3% by mass or less, and particularly preferably 2% by mass or less. In order to obtain a polypropylene having such CXS, a method of increasing the catalytic activity when obtaining a resin, a method of washing the obtained resin with a solvent or the propylene monomer itself, and the like can be used.

From the same point of view, the mesopentad fraction of the polypropylene is preferably 0.95 or more, more preferably 0.97 or more. The mesopentad fraction is an index indicating the stereoregularity of the crystalline phase of polypropylene measured by nuclear magnetic resonance (NMR). This is preferable because it increases the dielectric breakdown voltage. The upper limit of the mesopentad fraction is not particularly specified. In order to obtain a resin with such high stereoregularity, there are methods such as washing the resin powder obtained with a solvent such as n-heptane, selecting a catalyst and/or co-catalyst, and appropriately selecting a composition. preferably employed.

Such polypropylene more preferably has a melt flow index (MFR) of 1 to 10 g/10 minutes (230° C., 21.18 N load), particularly preferably 2 to 5 g/10 minutes (230° C., 21.18 N load). Those within the range are preferable from the viewpoint of film-forming properties. In order to set the melt flow index (MFR) to the above value, a method of controlling the average molecular weight and the molecular weight distribution is employed.

Such polypropylene is mainly composed of a homopolymer of propylene, but it may contain copolymerization components of other unsaturated hydrocarbons within a range not impairing the object of the present invention, and a polymer in which propylene is not used alone. may be blended. Examples of monomer components constituting such copolymer components and blends include ethylene, propylene (in the case of copolymerized blends), 1-butene, 1-pentene, 3-methylpentene-1, 3-methylbutene. -1,1-hexene, 4-methylpentene-1,5-ethylhexene-1,1-ocne, 1-decene, 1-dodecene, vinylcyclohexene, styrene, allylbenzene, cyclopentene, norbornene, 5-methyl-2 - includes norbornene and the like. From the standpoint of dielectric breakdown resistance and dimensional stability, the copolymerization amount or blend amount is preferably less than 1 mol % in terms of copolymerization amount and less than 10% by mass in terms of blend amount.

In addition, such polypropylene may contain various additives such as crystal nucleating agents, antioxidants, heat stabilizers, slip agents, antistatic agents, antiblocking agents, fillers, viscosity adjusting agents, etc., as long as they do not impair the purpose of the present invention. Agents, anti-coloring agents and the like can also be contained.

Among these, the selection of the type and amount of antioxidant to be added is important from the viewpoint of long-term heat resistance. That is, such antioxidants are preferably phenolic antioxidants having steric hindrance, at least one of which is of a high molecular weight type having a molecular weight of 500 or more. Various specific examples thereof include 2,6-di-t-butyl-p-cresol (BHT: molecular weight 220.4) and 1,3,5-trimethyl-2,4,6- Tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene (for example, BASF Japan Irganox (registered trademark) 1330: molecular weight 775.2) or tetrakis [methylene-3 (3,5-di-t- Butyl-4-hydroxyphenyl)propionate]methane (eg Irganox 1010 manufactured by BASF Japan; molecular weight 1177.7) is preferably used in combination. The total content of these antioxidants is preferably in the range of 0.03 to 1.0% by mass with respect to the total mass of polypropylene. If the amount of antioxidant is too small, the long-term heat resistance may be poor. If the amount of the antioxidant is too large, blocking at high temperature due to bleeding out of the antioxidant may adversely affect the magnetic recording medium. A more preferable content is 0.1 to 0.9% by mass, and particularly preferably 0.2 to 0.8% by mass.

When the resin film in the present invention is a polyarylene sulfide film, it is preferably a film containing a polyarylene sulfide resin as a main component. Here, the main component means that it accounts for 60% by mass or more of the raw material constituting the film.

In the present invention, the polyarylene sulfide resin refers to a polymer having -(Ar-S)- repeating units. Ar includes units represented by the following formulas (A) to (K).

(R1 and R2 are substituents selected from hydrogen, an alkyl group, an alkoxy group and a halogen group, and R1 and R2 may be the same or different)
As the repeating unit, the p-arylene sulfide unit represented by the above formula (A) is preferable, and representative examples thereof include polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfide ketone, and the like. As the arylene sulfide unit, a p-phenylene sulfide unit is preferably exemplified from the viewpoint of film properties and economy.

The polyarylene sulfide resin used in the present invention preferably comprises p-phenylene sulfide units represented by the following structural formula as main structural units in 80 mol % or more and 99.9 mol % or less of all repeating units. By setting it as said composition, the outstanding heat resistance and chemical resistance can be exhibited.

It can also be copolymerized with copolymer units in the range of 0.01 mol % or more and 20 mol % or less of the repeating units.
Preferred copolymer units are

（ここでＲはアルキル、ニトロ、フェニレン、アルコキシ基を示す。）が挙げられ、特に好ましい共重合単位は、ｍ－フェニレンスルフィド単位である。

(Here, R represents an alkyl, nitro, phenylene, or alkoxy group), and particularly preferred copolymer units are m-phenylene sulfide units.

The mode of copolymerization with the copolymerization component is not particularly limited, but a random copolymer is preferred.

The polyarylene sulfide film of the present invention may be an unstretched film, a uniaxially stretched film, or a biaxially stretched film, but from the viewpoint of finally achieving a thin film, a uniaxially or biaxially stretched film is preferred.

When the resin film in the present invention is a polyamide resin film, examples of the polyamide resin include polymers formed by amide bonding of a plurality of monomers. Typical examples thereof include aliphatic polyamides such as 6-nylon, 6,6-nylon, 6,10-nylon, 11-nylon, 12-nylon, and poly(meta-xylene adipamide). be done. In addition, copolymers of two or more elements such as 6-nylon/6,6-nylon, 6-nylon/6,10-nylon, 6-nylon/11-nylon, 6-nylon/12-nylon, etc. Combined is fine. In addition, one containing an aromatic component in either one of the diamine and the dicarboxylic acid is also preferably used.

The general formula of the aromatic diamine is shown below. Examples of compounds that can constitute the aromatic diamine unit represented by the general formula include orthoxylylenediamine, metaxylylenediamine and paraxylylenediamine. These can be used individually by 1 type or in combination of 2 or more types.

Examples of dicarboxylic acid units containing aromatic components include phthalic acid, isophthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, and the like.

The resin film of the present invention contains inert particles in the resin forming the resin film in order to optimize the height of the protrusions on the surface of the film layer and the surface roughness for the purpose of improving the handleability when it is made into a thin film. can be made Examples of inert particles include inorganic particles such as spherical silica, aluminum silicate, titanium dioxide, and calcium carbonate. Other organic polymer particles include crosslinked polystyrene resin particles, crosslinked silicone resin particles, crosslinked acrylic resin particles, Crosslinked styrene-acrylic resin particles, crosslinked polyester particles, polyimide particles, melamine resin particles and the like are preferred. One or more of these can be selected and used.

The size of the inert particles is preferably 0.01 μm or more and 1 μm or less, more preferably 0.05 μm or more and 0.7 μm or less, and particularly preferably 0.1 μm or more and 0.5 μm or less.

Regarding the method of adding inert particles to the resin, there are cases where particles are added to a part of the components constituting the resin and polymerized as it is in a slurry state, and addition using a twin-screw extruder after polymerization of the resin. There are multiple ways. The amount of inert particles added is preferably 0.001% to 2%, more preferably 0.01% to 1%, and particularly preferably 0.1% to 0.8%, based on the total weight of the film. is.

The layer structure of the resin film may be a single layer, or two or more layers having different surface roughnesses on the front and back surfaces. Especially when it is used as a base material of a magnetic recording medium, it is preferable to have a layered structure of two or more layers. In the case of a structure of two or more layers, particles may not be added to the resin constituting the outermost layer.

The resin film of the present invention may be provided with a coating layer for the purpose of improving adhesion with the magnetic layer and improving the slipperiness of the film itself.

The method for producing the resin film of the present invention can employ a method known per se, for example, extruding the polymer from a die using a single extruder into a sheet, or using two or more extruders. A step of laminating different polymers in a molten state, extruding them into a sheet from a die, cooling and solidifying the resulting sheet to form a single-layer or laminated unstretched resin film, and the resulting unstretched resin film. , preferably by stretching in one direction or two directions perpendicular to each other, followed by heat treatment. The temperature in the process of extruding in a molten state is not particularly limited as long as there is no unmelted material and the temperature does not excessively promote thermal deterioration of the resin. Temperature is preferred. Next, for cooling, in order to reduce thickness unevenness while maintaining the flatness of the resulting unstretched resin film, a rotating cooling drum installed below the die along the film forming direction is used. It is preferable to bring the sheet material into close contact with it and cool it. If the desired thickness and Young's modulus can be achieved, it is not impossible to use the unstretched film as it is. It is preferred to produce films that have a thickness and a Young's modulus. The stretching method includes longitudinal uniaxial stretching, horizontal uniaxial stretching, sequential biaxial stretching, and simultaneous biaxial stretching, and is not particularly limited, but sequential biaxial stretching will be explained here. The longitudinal uniaxial stretching is obtained by omitting the lateral stretching from the sequential biaxial stretching, the lateral uniaxial stretching is the sequential biaxial stretching without the longitudinal stretching, and the simultaneous biaxial stretching is performed simultaneously with longitudinal and lateral stretching. In the sequential biaxial stretching, the unstretched resin film is stretched uniaxially (usually in the longitudinal direction) at a temperature of (Tg−10)° C. to (Tg+60)° C., where Tg is the glass transition temperature of the resin, and is preferably doubled or more. It is preferably stretched at a draw ratio of 2.5 times or more, and then stretched at a temperature of Tg to (Tg+60)° C. at a draw ratio of 2 times or more, preferably at a draw ratio of 2.5 times or more in a direction orthogonal to the drawing direction. Furthermore, it may be stretched again in the longitudinal direction and/or the transverse direction as necessary. Furthermore, the stretched resin film can be heat-set at a temperature of (Tm-70)° C. to (Tm-10)° C., where Tm is the melting point of the resin. The heat setting time is preferably 0.1 to 60 seconds.

The resin film of the present invention is preferably used as a base film for magnetic recording tapes, high-density magnetic recording tapes, especially digital recording magnetic recording tapes. Therefore, the magnetic recording tape using the resin film of the present invention will be further described.

The magnetic recording tape of the present invention can be produced by forming a magnetic layer on the resin film described above. On the surface of the resin film of the present invention, in order to improve adhesion to the magnetic layer or the like, a coating layer or the like having an easy-adhesion function known per se is formed within a range that does not impair the effects of the present invention. You can

The magnetic layer forming the magnetic recording tape of the present invention is not particularly limited. It is formed by uniformly dispersing in and applying the coating liquid. It can be a magnetic recording tape.

By the way, as mentioned above, it is necessary to miniaturize the magnetic material in order to increase the recording density. It became necessary to do in Then, the present inventors have newly discovered that when a film having an extremely flat surface is processed at a high temperature, problems such as wrinkles occur, and the present invention has been accomplished.

The magnetic layer should be coated so that its thickness is 1 μm or less, more preferably 0.1 to 1 μm. It is preferable from the viewpoint of providing a coated magnetic recording tape for high density recording with less dropout and less error rate. If necessary, it is also preferable to coat a non-magnetic layer containing fine titanium oxide particles or the like dispersed in the same organic binder as the magnetic layer as an underlayer of the coating type magnetic layer.

On the surface of the magnetic layer, a protective layer such as diamond-like carbon (DLC) and a fluorine-containing carboxylic acid-based lubricating layer are sequentially provided according to the purpose, application, and need, and a known back coat layer is provided on the other surface. may be provided.

The coated magnetic recording tape thus obtained is extremely useful as a magnetic tape for data applications such as LTO and enterprise. In particular, according to the present invention, since accurate tracking is possible by adjusting the tape tension, it is possible to dramatically improve the track density on the linear tape.

EXAMPLES The present invention will be described more specifically with reference to examples and comparative examples below. In addition, in the present invention, the characteristics were measured and evaluated by the following methods.
(1) Young's modulus The obtained film was cut into a sample width of 10 mm and a length of 15 cm, and the chuck distance was 100 mm, the tensile speed was 10 mm/min, and the chart speed was 500 mm/min. Tensilon). The Young's modulus is calculated from the tangent to the rising portion of the obtained load-elongation curve.
(2) Thickness of Film Ten sheets of film are piled up so as not to contain dust, and the thickness is measured with a dot type electronic micrometer, and the thickness of one sheet is calculated.
(3) Film elongation under high temperature and high tension A film is cut into a lengthwise direction of 30mm and a widthwise direction of 4mm, and set in a thermomechanical property measurement tester EXSTR-6000 manufactured by Seiko Instruments Inc. so that the chuck distance is 20mm. With a load of 2 kg / mm ² applied in the longitudinal direction of the film, the temperature was raised from 30 ° C. to 170 ° C. at a heating rate of 5 ° C./min, and the length (L1) and 110 at 30 ° C. in the longitudinal direction of the sample Elongation (%) is calculated according to the following formula from the length (L2) in °C.
110°C elongation (%) = (L2-L1)/L1 x 100
(4) Dynamic viscoelasticity A sample cut to a length of 30 mm and a width of 5 mm was set in a viscoelasticity measuring device DMA-8000 manufactured by PerkinElmer, with a chuck interval of 11 mm and an amplitude of 0.1 mm. The temperature is raised at a temperature elevation rate of 2° C./min. Obtain the tan delta peak temperature at a frequency of 1 Hz.
(5) Preparation of magnetic recording tape A film slit to a width of 1 m was transported under a tension of 2 kg/mm ² , and a magnetic coating and a non-magnetic coating were applied to one surface of the support according to the following description to obtain a tape having a width of 12.65 mm. Slit and create pancakes. Then, a 200 m long piece of this pancake was incorporated into a cassette to form a magnetic tape.

(Hereinafter, "parts" means "parts by mass.")
<Coating liquid for magnetic layer formation>
Barium ferrite magnetic powder 100 parts (plate diameter: 20.5 nm, plate thickness: 7.6 nm, tabular ratio: 2.7, Hc: 191 kA/m (≈2400 Oe)
Saturation magnetization: 44 Am2/kg, BET specific surface area: 60 m2/g)
Polyurethane resin 12 parts Mass average molecular weight 10,000
Sulfonic acid functionality 0.5 meq/g
α-Alumina HIT60 (manufactured by Sumitomo Chemical Co., Ltd.) 8 parts Carbon black #55 (manufactured by Asahi Carbon Co., Ltd.)
Particle size 0.015 μm 0.5 parts Stearic acid 0.5 parts Butyl stearate 2 parts Methyl ethyl ketone 180 parts Cyclohexanone 100 parts <Coating solution for forming non-magnetic layer>
Non-magnetic powder α-iron oxide 85 parts Average major axis length 0.09 μm, specific surface area by BET method 50 m ² /g
pH 7
DBP oil absorption 27-38ml/100g
Surface treatment layer Al2O3 8% by mass
Carbon black 15 parts “Conductex” (registered trademark) SC-U (manufactured by Columbian Carbon)
Polyurethane resin UR8200 (manufactured by Toyobo Co., Ltd.) 22 parts Phenylphosphonic acid 3 parts Cyclohexanone 140 parts Methyl ethyl ketone 170 parts Butyl stearate 1 part Stearic acid 2 parts Methyl ethyl ketone 205 parts Cyclohexanone 135 parts

Each component of each of the above coating liquids (magnetic layer forming coating liquid and non-magnetic layer forming coating liquid) was kneaded with a kneader. The coating liquid was pumped through a horizontal sand mill filled with zirconia beads of 1.0 mmφ in an amount of 65% by volume with respect to the volume of the dispersion part, and was run at 2,000 rpm for 120 minutes (substantially retained in the dispersion part time), dispersed. Polyisocyanate was added to the resulting dispersion in 5.0 parts for the non-magnetic layer coating material and 2.5 parts for the magnetic layer coating material, and 3 parts of methyl ethyl ketone was added. The mixture was filtered through a filter to prepare a coating solution for forming a non-magnetic layer and a coating solution for forming a magnetic layer.

The resulting non-magnetic layer-forming coating solution was coated on a film so that the thickness after drying was 0.8 μm, and dried. It was coated to a thickness of 0.07 μm, and while the magnetic layer was still wet, it was oriented by a cobalt magnet with a magnetic force of 6,000 G (600 mT) and a solenoid with a magnetic force of 6,000 G (600 mT), and dried. rice field. Then, the back coat layer (carbon black average particle size: 17 nm 100 parts, calcium carbonate average particle size: 40 nm 80 parts, α-alumina average particle size: 200 nm 5 parts) is added to the polyurethane resin so that the thickness after calendering is 0.5 μm. , dispersed in polyisocyanate) was applied. Next, after calendering with a calender at a temperature of 90° C. and a linear pressure of 300 kg/cm (294 kN/m), it was cured at 70° C. for 48 hours. Further, the nonwoven fabric and the razor blade were attached to a device having a slit product feeding and winding device so that the nonwoven fabric and the razor blade pressed against the magnetic surface, and the surface of the magnetic layer was cleaned with a tape cleaning device to obtain a magnetic tape.

(6) Dimensional change in the width direction when tension is applied to the magnetic recording tape In an atmosphere with a temperature of 23°C and a humidity of 50%, the magnetic material slit to a width of 12.65 mm (1/2 inch) prepared in (5) above. A tape (30 cm long) is set as shown in FIG.
In this state, a weight of 0.2 N is attached to one side of the magnetic tape (the other side is fixed), and the width (T1) of the magnetic tape at that time is measured with a Keyence laser outer diameter measuring device (LS-9030N).
After that, the weight is changed to 1.2 N, and the width (T2) of the magnetic tape at that time is measured with a Keyence laser outer diameter measuring device (LS-9030N).
The amount of change in width dimension per 1N was calculated from the following equation.
Width dimensional change (ppm) = (T1-T2)/T1 x 1000,000
Furthermore, this measurement was repeated three times, and the average value was defined as the amount of change in dimension in the width direction per 1N.

(7) Measurement of Weight Average Molecular Weight (Mw) and Molecular Weight Distribution (Mw/Mn) of Polypropylene Measurement was performed using GPC (gel permeation chromatography) under the following conditions.
Measuring instrument: manufactured by Tosoh Corporation, high-temperature GPC with built-in differential refractometer (RI), HLC-8121GPC/HT type Column: manufactured by Tosoh Corporation, three TSKgel GMHhr-H (20) HT connected Column temperature: 145 ° C.
Eluent: Trichlorobenzene Flow rate: 1.0 ml/min
Standard polystyrene manufactured by Tosoh Corporation was used to prepare a calibration curve, and the measurement results were converted to polypropylene values.

(8) Measurement of Stereoregularity Distribution of Polypropylene by Sequential Extraction Method The polypropylene resin was sufficiently dissolved in (1) xylene under reflux, and then allowed to stand at room temperature for 4 hours. A part insoluble in xylene was filtered off, and the insoluble part was subjected to the next extraction. The soluble matter was weighed after drying xylene. This mass was defined as the amount of atactic component. For the xylene-insoluble matter, a Soxhlet fat extractor was used, and (2) n-pentane, (3) n-hexane, and (4) n-heptane were sequentially extracted in order of Soxhlet extraction for 6 hours each. The final extraction residue that was insoluble even in n-heptane was weighed, and this mass was used as the amount of the isotactic component. It was expressed as a percentage ratio to the resin mass before dissolution in xylene.

(9) Processability In the step of applying and drying the magnetic paint in the above (5) preparation of the magnetic recording tape, the state of the web after drying was observed and evaluated according to the following criteria.
◎: 0 wrinkles/1 m width after drying ○: 1 wrinkle/1 m width after drying ×: 2 or more wrinkles/1 m width after drying

[Example 1]
A PEN resin composition 1 having an intrinsic viscosity (orthochlorophenol, 35°C) of 0.60 dl/g containing 0.1% by weight of crosslinked polystyrene particles having an average particle size of 0.2 µm was heated at 180°C for 5 hours in the form of chips. After drying, it is supplied to an extruder hopper, melted at 300 ° C. in the extruder, extruded from a T-shaped extrusion die onto a casting drum maintained at a surface finish of 0.3 S and a surface temperature of 60 ° C., and rapidly solidified. An unstretched film was obtained.

The unstretched film thus obtained was preheated at 120° C., further heated by an infrared heater with a surface temperature of 830° C. from 14 mm above between low-speed and high-speed rolls, stretched 4 times, and quenched. Subsequently, it was supplied to a stenter, stretched 4.6 times in the transverse direction at 150 ° C., further stretched 1.25 times in the transverse direction at 160 ° C., and heat-set at 205 ° C. for 3 seconds to have a thickness of 3.0 μm. film. The Young's modulus of the obtained film was 6 GPa in the longitudinal direction and 11 GPa in the transverse direction. Table 1 shows the properties of the obtained film.

[Examples 2 and 3]
A biaxially stretched film was obtained in the same manner as in Example 1 except that the PEN resin composition 1 of Example 1 was used and the stretching ratio and thickness were changed as shown in Table 1. Table 1 shows the properties of the obtained film.

[Example 4]
95 parts of dimethyl naphthalene-2,6-dicarboxylate, 4 parts of dimethyl isophthalate (5 mol % with respect to the total amount of all dicarboxylic acid components) and 60 parts of ethylene glycol, and 0.03 of manganese acetate tetrahydrate as a transesterification catalyst 0.1% by weight of silica particles having an average particle diameter of 0.3 μm are added as a lubricant, and transesterification is performed according to a conventional method, and then 0.023 part of trimethyl phosphate is added to substantially esterify The exchange reaction was terminated.

Next, 0.024 part of antimony trioxide was added, and then the polymerization reaction was carried out in a conventional manner at a high temperature and in a high vacuum. A PEN resin composition 2 containing silica particles in 1 mol % polyethylene-2,6-naphthalate copolymer was obtained. The obtained copolymer was dried and extruded in the same manner as in Example 1 to obtain an unstretched film, then preheated to 110° C. and further passed between low speed and high speed rolls from 14 mm above to a surface temperature of 800° C. The film was heated with an infrared heater and stretched 4.3 times, quenched, supplied to a stenter, stretched 6 times in the transverse direction at 150°C, and heat-set at 200°C for 3 seconds to obtain a thickness of 2. A 5 μm film was obtained. Table 1 shows the properties of the obtained film.

[Example 5]
Using the PEN resin composition 1 of Example 1, an unstretched film was obtained in the same manner as in Example 1, then supplied to a stenter without longitudinal stretching, preheated at 160 ° C., and stretched 5 times at 150 ° C. A film with a thickness of 3.5 μm was obtained. Table 1 shows the properties of the obtained film.

<Preparation of PET-based raw materials>
(1-a) Production of PET Pellets: 194 parts by mass of dimethyl terephthalate and 124 parts by mass of ethylene glycol were charged into a transesterification reactor, and the contents were heated to 140° C. to dissolve. After that, 0.3 parts by mass of magnesium acetate tetrahydrate and 0.05 parts by mass of antimony trioxide were added while stirring the contents, and transesterification was carried out at 140 to 230° C. while distilling off methanol. Next, 0.5 parts by mass of a 5% by mass ethylene glycol solution of trimethyl phosphate (0.025 parts by mass as trimethyl phosphate) and 0.3 parts by mass of a 5% by mass ethylene glycol solution of sodium dihydrogen phosphate dihydrate Parts by mass (0.015 parts by mass as sodium dihydrogen phosphate dihydrate) were added.

Addition of the ethylene glycol solution of trimethyl phosphate lowers the temperature of the reaction contents. Therefore, stirring was continued until the temperature of the reaction contents returned to 230° C. while distilling off excess ethylene glycol. After the temperature of the reaction contents in the transesterification reactor reached 230° C. in this manner, the reaction contents were transferred to the polymerization apparatus.

After the transition, the temperature of the reaction system was gradually raised from 230°C to 275°C, and the pressure was lowered to 0.1 kPa. The time to reach the final temperature and final pressure was both 60 minutes. After reaching the final temperature and final pressure, the reaction was continued for 2 hours (3 hours from the start of polymerization). The value shown by polyethylene terephthalate with an intrinsic viscosity of 0.55 was used as a predetermined value). Therefore, the reaction system was purged with nitrogen and returned to normal pressure to stop the polycondensation reaction, discharged into cold water in the form of a strand, and immediately cut into polyethylene terephthalate PET having an intrinsic viscosity (ortho-chlorophenol, 35°C) of 0.55 dl/g. Pellets were obtained (raw material-1a).

Using a rotary vacuum polymerization apparatus, the above PET pellets (raw material-1a) were heat-treated for a long time at a temperature of 230 ° C. under a reduced pressure of 0.1 kPa, and the intrinsic viscosity (ortho-chlorophenol, 35 ° C.) was 0.70 dl. /g (raw material-1ak).

(1-b) Preparation of copolymerized PET pellets; 180 parts by weight of dimethyl terephthalate, 20 parts by weight of dimethyl isophthalate, and 129 parts by weight of ethylene glycol were charged into an ester exchange reactor, and the contents were heated to 140°C to dissolve. bottom. After that, 0.3 parts by mass of magnesium acetate tetrahydrate and 0.05 parts by mass of antimony trioxide were added while stirring the contents, and transesterification was carried out at 140 to 230° C. while distilling off methanol. Next, 0.5 parts by mass of a 5% by mass ethylene glycol solution of trimethyl phosphate (0.025 parts by mass as trimethyl phosphate) and 0.3 parts by mass of a 5% by mass ethylene glycol solution of sodium dihydrogen phosphate dihydrate Parts by mass (0.015 parts by mass as sodium dihydrogen phosphate dihydrate) were added.

Addition of the ethylene glycol solution of trimethyl phosphate lowers the temperature of the reaction contents. Therefore, stirring was continued until the temperature of the reaction contents returned to 230° C. while distilling off excess ethylene glycol. After the temperature of the reaction contents in the transesterification reactor reached 230° C. in this manner, the reaction contents were transferred to the polymerization apparatus.

After the transition, the temperature of the reaction system was gradually raised from 230°C to 275°C, and the pressure was lowered to 0.1 kPa. The time to reach the final temperature and final pressure was both 60 minutes. After reaching the final temperature and final pressure, the reaction was continued for 2 hours (3 hours from the start of polymerization). The value shown by polyethylene terephthalate with an intrinsic viscosity of 0.55 was used as a predetermined value). Therefore, the reaction system was purged with nitrogen and returned to normal pressure to stop the polycondensation reaction, discharged in cold water in the form of strands, and immediately cut into copolymerized polyethylene terephthalate having an intrinsic viscosity (ortho-chlorophenol, 35°C) of 0.55 dl/g. of PET pellets were obtained (raw material-1b).

Using a rotary vacuum polymerization apparatus, the above PET pellets (raw material-1b) were heat-treated for a long time at a temperature of 230 ° C. under a reduced pressure of 0.1 kPa, and the intrinsic viscosity (ortho-chlorophenol, 35 ° C.) was 0.70 dl. Solid-phase polymerization was carried out until the weight of the raw material was 1/g (raw material-1 bk).

(2) Preparation of particle-containing PET pellets: 90 parts by mass of the above-mentioned solid-phase polymerized PET pellets (raw material-1k: processing time 2 hours) in a co-rotating vented twin-screw kneading extruder heated to 280 ° C. and 10 parts by mass of a 10% by mass aqueous slurry of crosslinked polystyrene particles having an average particle size of 0.30 μm (1 part by mass as crosslinked polystyrene particles), and the vent hole is kept at a reduced pressure of 1 kPa or less to remove water, Particle-containing pellets (raw material-2) containing 1% by mass of crosslinked polystyrene particles and having an intrinsic viscosity (ortho-chlorophenol, 35° C.) of 0.62 dl/g were obtained.

(3) Preparation of two-component composition (PET/PEI) pellets: A co-rotating vented twin-screw kneading extruder (manufactured by Japan Steel Works, Ltd.) provided with three kneading paddle kneading units heated to a temperature of 280 ° C. , screw diameter 30 mm, screw length/screw diameter = 45.5), solid-phase polymerized PET pellets obtained by the above method (raw material -1ak: processing time 2 hours) and PEI "Ultem" manufactured by SABIC Innovative Plastics Co., Ltd. (registered trademark) 1010 pellets were fed and melt extruded at a shear rate of 100 sec ⁻¹ and a residence time of 1 minute to obtain binary composition pellets containing 50% by mass of PEI. The glass transition temperature of the prepared two-component composition pellet was 150° C. (raw material-3).

[Example 6]
90 parts by weight of PET pellets (raw material-1ak) and 10 parts by weight of particle-added PET pellets (raw material-2) were each dried at 170 ° C. for 3 hours, then supplied to an extruder hopper, and 280 parts by weight in the extruder. C., extruded from a T-shaped extrusion die onto a casting drum maintained at a surface finish of 0.3S and a surface temperature of 20.degree.

The unstretched film thus obtained was preheated at 70° C., further heated from 14 mm above by an infrared heater with a surface temperature of 800° C. between low-speed and high-speed rolls, stretched 4 times, and quenched. Subsequently, the film was supplied to a stenter, stretched 3.5 times in the transverse direction at 100°C, and heat-set at 205°C for 3 seconds to obtain a film having a thickness of 3.5 µm. Table 1 shows the properties of the obtained film.

[Example 7]
70 parts by weight of PET pellets (raw material 1-ak), 10 parts by weight of particle-added PET pellets (raw material-2), and 20 parts by weight of polyetherimide-containing PET pellets (raw material-3) are mixed, then dried and carried out. An unstretched film was obtained in the same manner as in Example 6. A film having a thickness of 3.7 μm was obtained in the same manner as in Example 6 except that the draw ratio was changed as shown in Table 1. Table 1 shows the properties of the obtained film.

[Example 8]
40 parts by weight of PET pellets (raw material-1ak), 30 parts by weight of isophthalic acid copolymer PET pellets (raw material-1bk), 10 parts by weight of particle-added PET pellets (raw material-2), PET pellets containing polyetherimide (raw material -3) 20 parts by weight were mixed and then dried to obtain an unstretched film in the same manner as in Example 6. A film having a thickness of 4.2 μm was obtained in the same manner as in Example 6 except that the draw ratio was changed as shown in Table 1. Table 1 shows the properties of the obtained film.

[Example 9]
As a thermoplastic polyetherketone resin, 100 parts by mass of a polyetheretherketone resin (manufactured by Victrex: polyetheretherketone 381G, Tg: 142°C, Tm: 343°C) was added with an inert fine particle having an average particle diameter of 0.5. A mixture (PEEK-1) containing 0.1 part by mass of 3 μm spherical silica particles was prepared, dried at 150° C. for 3 hours, melt-extruded at 380° C. with an extruder, and cast in a casting drum maintained at 80° C. Cast up to create an unstretched film.

Then, the film was biaxially stretched successively in the machine direction and then in the transverse direction under the following conditions, and further heat-set and heat-relaxed to obtain a biaxially stretched film having a thickness of 3 μm.

That is, the unstretched film was stretched 2.8 times in the longitudinal direction (machine axis direction) at 155 ° C., and then led to a tenter. The film was preheated at a temperature of 145° C. for 20 seconds, and then stretched 2.5 times in the transverse direction (perpendicular to the machine axis direction and the thickness direction). At that time, the stretching speed in the transverse direction was 5000%/min. Further, the temperature for stretching in the transverse direction was 145° C. for the first stage, 150° C. for the second stage, and 160° C. for the third stage (final stage). After that, the film was heat-set at 245° C. for 5 seconds, and further relaxed to 3% in the transverse direction while cooling to 180° C. to obtain a biaxially stretched film having a thickness of 3.0 μm. Table 1 shows the properties of the obtained film.

[Example 10]
Particle-added polyether ether ketone resin (PEEK-1) used in Example 9, and separately from this, inert fine particles of PEEK-1 and 0.1 parts by mass of spherical silica particles having an average particle size of 0.1 μm A modified polyetheretherketone resin (PEEK-2) was prepared. After drying each resin at 150° C. for 3 hours, it is put into two separate extruders, and a layer A made of PEEK-1 and a layer B made of PEEK-2 are formed in a feed block at a thickness ratio of 1:1. An unstretched film was prepared in the same manner as in Example 9, except that the thickness of the unstretched film was changed to form a two-layer laminated film.

Next, from the conditions described in Example 9, the draw ratio was changed as described in Table 1 to obtain a biaxially stretched film with a thickness of 3.5 μm in which the surface of layer B was flatter than the surface of layer A. . Table 1 shows the properties of the obtained film.

<Preparation of PPS resin>
<PPS-1>
16.5 kg of sodium sulfide (including 49 wt% of water of crystallization), 6.5 kg of sodium hydroxide, 5.2 kg of sodium acetate, and 22.0 kg of N-methyl-2-pyrrolidone (hereinafter sometimes abbreviated as NMP) were charged. After dehydration at 210° C., 20.5 kg of 1,4-dichlorobenzene (abbreviated as p-DCB) and 20.0 kg of NMP were added and reacted at 265° C. for 5 hours. The reaction product was washed with water and dried to obtain phenylene sulfide. The obtained PPS had a glass transition temperature of 90° C., a melting point of 280° C., a number average molecular weight of 11,500, a weight average molecular weight of 40,000, and contained an elemental sodium content of 165 ppm and an elemental chlorine content of 2,000 ppm.

<PPS-2>
PPS-1 was washed with 70 liters of deionized water containing 32 g of acetic acid, then washed again with water and dried to obtain phenylene sulfide. The obtained PPS had a glass transition temperature of 90° C., a melting point of 280° C., a number average molecular weight of 11,500, a weight average molecular weight of 40,000, and contained 85 ppm of sodium element and 300 ppm of chlorine element.

<PPS-3>
Diiodinated benzene and sulfur were further charged with diphenyl disulfide and heated to 180° C. to melt and mix them completely, after which the temperature was raised to 220° C. and the pressure was lowered to 200 Torr. The resulting mixture was polymerized for 8 hours while changing the temperature and pressure stepwise so that the final temperature and pressure were 320° C. and 1 Torr, respectively. PPS-3 was obtained by the polymerization reaction. The resulting PPS-3 has a glass transition temperature of 90° C., a melting point of 277° C., a number average molecular weight of 12,000 and a weight average molecular weight of 42,000. was not detectable (less than 50 ppm).

[Example 11]
To the PPS-3, 3,9-bis[2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1 as an antioxidant (B) -Dimethylethyl]-2,4,8,10-tetraoxaspirio[5-5]undecane (manufactured by Sumitomo Chemical Co., Ltd.: trade name SUMILIZER GA-80, 1 mass% weight loss temperature 348 ° C., melting point 120 ° C.): 2% by mass, crosslinked polystyrene particles having an average particle size of 0.3 μm as inert particles were added so as to be 0.1% by mass with respect to the mass of the biaxially stretched film obtained, and these were placed in a biaxial extruder. to obtain a PPS resin composition. After drying this PPS resin composition under reduced pressure at 170°C for 4 hours, it is melt extruded at 290°C with an extruder, extruded through a die having a linear lip, cast onto a metal drum whose surface is kept at 25°C, and cooled to solidify. to obtain an unstretched film.

This film is stretched 3.5 times at a film temperature of 100°C by a longitudinal stretching device consisting of rolls, then stretched 3.5 times at a final transverse stretching temperature of 105°C using a tenter, and further stretched in the same tenter. in a subsequent heat treatment chamber at 265° C. for 15 seconds under tension, followed by 4% widthwise relaxation at 170° C. to obtain a PPS biaxially stretched film with a thickness of 3 μm. At that time, the transverse stretching part is divided into three zones (first zone, second zone, third zone), the first zone is stretched at a temperature of 95 ° C. and the magnification is 1.8 times, and the second zone is stretched. was 1.49 times at a temperature of 100.degree. The draw ratio for each zone is the ratio of the exit width to the entrance width of each zone. Table 1 shows the properties of the obtained film.

[Example 12]
125 parts of dimethyl naphthalene-2,6-dicarboxylate, 60 parts of trimethylene glycol, 0.03 parts of manganese acetate tetrahydrate as a transesterification catalyst, and finally silica particles having an average particle size of 0.3 μm as a lubricant. After adding 0.05% by weight based on the weight of the polymer obtained practically and carrying out the transesterification reaction according to a conventional method, 0.023 part of trimethyl phosphate is added to substantially complete the transesterification reaction. let me Next, 0.024 part of antimony trioxide was added, and then the polymerization reaction was carried out in a conventional manner at a high temperature and in a high vacuum to obtain a polytrimethylene-2,6-naphthalate polymer with an intrinsic viscosity of 0.61 dl/g. rice field. The pellets of the resulting polymer were dried at 150°C for 4 hours, then melted at 280°C in a melt extruder and passed through a T-type extrusion die to a casting drum maintained at a surface finish of 0.3S and a surface temperature of 25°C. It was extruded upwards and quenched to solidify to obtain an unstretched film. The obtained unstretched film was preheated at 75° C., further heated by an infrared heater with a surface temperature of 800° C. from 14 mm above between low-speed and high-speed rolls, stretched 4 times, quenched, and then followed by a stenter. The film was preheated at 80° C., stretched 3 times in the transverse direction at 110° C., and heat-set at 145° C. for 3 seconds to obtain a film having a thickness of 4.5 μm. Table 1 shows the properties of the obtained film.

[Example 13]
0.15% by weight of crosslinked polystyrene particles having an average particle size of 0.2 μm were added to Mitsubishi Gas Chemical Nylon MXD6 (grade S6007) as inert particles, dried at 170° C. for 4 hours, and then extruded at 260°C with a melt extruder. C. and extruded from a T-shaped extrusion die onto a casting drum maintained at a surface finish of 0.3S and a surface temperature of 30.degree. The obtained unstretched film was introduced into a linear motor type simultaneous biaxial stretching system, preheated at 85° C., stretched 3.6 times in the vertical direction and 3.6 times in the horizontal direction at 120° C., and further stretched. A heat setting treatment was performed in an oven at 210° C. for 10 seconds to obtain a film with a thickness of 4 μm. Table 1 shows the properties of the obtained film.

[Example 14]
A polypropylene resin pellet having a weight average molecular weight (Mw) of 3.1 × 10 ⁵ , a molecular weight distribution (Mw/Mn) of 7.4, and an isotactic component fraction of 97.7% by mass is supplied to an extruder to obtain a resin. It was melted at a temperature of 250° C., extruded using a T-die, wound around a metal drum whose surface temperature was kept at 90° C., and solidified to produce an unstretched cast material sheet having a thickness of about 200 μm. Subsequently, this unstretched cast material sheet was kept at 140° C., stretched longitudinally 5 times in the machine direction, and immediately cooled to room temperature. Then, the film was transversely stretched 10 times in the width direction at 170° C. using a tenter to obtain a thin biaxially stretched polypropylene film having a thickness of 4.0 μm. Table 1 shows the properties of the obtained film.

[Comparative Example 1]
A film was obtained in the same manner as in Example 6 except that the same resin as in Example 6 was used and the draw ratio and thickness were changed as shown in Table 1. Table 1 shows the properties of the obtained film. Since the product of the longitudinal Young's modulus and the thickness exceeded the range of the present invention, the dimensional change in the width direction of the magnetic tape was small when the tension was changed.

[Comparative Example 2]
A film was obtained in the same manner as in Example 6 except that the same resin as in Example 1 was used and the draw ratio and thickness were changed as shown in Table 1. Table 1 shows the properties of the obtained film. Since the product of the longitudinal Young's modulus and the thickness exceeded the range of the present invention, the dimensional change in the width direction of the magnetic tape was small when the tension was changed.

[Comparative Example 3]
90 parts by weight of isophthalic acid copolymer PET pellets (raw material-1bk) and 10 parts by weight of particle-added PET pellets (raw material-2) were mixed and dried at 150° C. for 6 hours. to obtain an unstretched film. The obtained unstretched film was stretched at the ratio shown in Table 1 to obtain a film with a thickness of 4 μm. The product of the thickness and Young's modulus of the obtained film was within the range of the present invention, but the elongation at high temperature under load was large, and wrinkles occurred during the magnetic paint coating process, resulting in poor processing process suitability. Met.

[Comparative Example 4]
Using 100 parts by weight of dimethyl terephthalate, 60 parts by weight of 1,3-propanediol and 0.08 parts by weight of tetrabutyl titanate, transesterification was carried out. Next, spherical silica particles with an average diameter of 0.3 μm were added as a lubricant so as to be 0.05% by weight per polymer, and the polycondensation reaction was carried out under high vacuum. Methylene terephthalate was obtained.

This polytrimethylene terephthalate was melt-extruded through a die slit and solidified by contact cooling on a casting drum to prepare an unstretched film. While heating this unstretched film with an infrared heater, it is stretched 3.1 times in the longitudinal direction (machine axis direction) at 55 ° C., and then in the transverse direction (width direction) in the tenter at 55 ° C. It is successively doubled to 3.4 times. The film was axially stretched and heat-treated at 150° C. while relaxing 3% in the width direction to obtain a biaxially oriented film with a thickness of 4 μm. The product of the thickness and Young's modulus of the obtained film was within the range of the present invention, but the elongation at high temperature under load was large, and wrinkles occurred during the magnetic paint coating process, resulting in poor processing process suitability. rice field.

[Comparative Example 5]
An attempt was made to obtain a film by using the same polymer as in Example 6 and adjusting the draw ratio and thickness as shown in Table 1, but the film could not be collected due to cutting during transverse drawing.

In Table 1, PEN is polyethylene-2,6-naphthalate, PET is polyethylene terephthalate, PEEK is polyetheretherketone, PPS is polyphenylene sulfide, C3Q is polytrimethylene-2,6-naphthalate MXD6 is Mitsubishi Gas Chemical's nylon MXD6 (Grade S6007), PP is polypropylene, C3T is polytrimethylene terephthalate, PEI is polyetherimide, PPE is polyphenylene ether, YMD is Young's modulus in MD, YTD is Young's modulus in TD. Moreover, the ratio of the copolymer component represents the molar fraction when the acid or glycol is 100, and the ratio of the blend component represents the weight fraction when the whole polymer is 100.

The resin film of the present invention is particularly suitable for use as a base film for magnetic recording tapes such as high-capacity data storage.

20... magnetic tape, 21, 23... mount, 22... dimension measuring machine, 22a... light-emitting part of transmitter, 30... receiver, 30b... light-receiving part of receiver, 24... laser light, 25... cylinder surface mounting surface

Claims (6)

Young's modulus in the longitudinal direction of the film measured at a tensile speed of 10 mm / min is 1 GPa or more and 6 GPa or less, the thickness of the film is 1 µm or more and 4.5 µm or less, and the longitudinal Young's modulus and thickness are measured at a tensile speed of 10 mm / min. The product of is 5 GPa · μm or more and 20 GPa · μm or less, and a load of 2 kg / mm ² is applied in the longitudinal direction and heated at a rate of 5 ° C./min to reach 110 ° C. The dimensional change in the longitudinal direction of the film is - 2% or more + 2% or less, a resin film used as a base film for a magnetic recording tape ,
A resin film comprising at least one resin selected from the group consisting of aromatic polyesters, polyetherketones, polyarylene sulfides, polyolefins, aliphatic polyamides and semi-aromatic polyamides . The resin film according to claim 1, wherein the tan δ peak temperature measured by DMA of the resin forming the resin film is in the range of 100°C or higher. Containing inert particles that are inorganic particles or organic polymer particles,
3. The resin film according to claim 1, wherein the content of the inert particles is 0.001% by weight or more and 2% by weight or less with respect to the total weight of the film. The resin film according to any one of claims 1 to 3 , wherein the product of Young's modulus in the longitudinal direction measured at a tensile speed of 10 mm/min and the thickness is 5 GPa·µm or more and 18 GPa·µm or less. The resin film according to any one of claims 1 to 4 , which is used as a base film of a high-density magnetic recording tape that adjusts the track position by controlling the tension applied in the running direction of the magnetic recording tape. A magnetic recording tape comprising the resin film according to any one of claims 1 to 5 and a magnetic layer provided on the surface of the resin film.

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