WO2020105471A1

WO2020105471A1 - Biaxially oriented thermoplastic resin film

Info

Publication number: WO2020105471A1
Application number: PCT/JP2019/043829
Authority: WO
Inventors: 千代敏弘; 鈴木維允; 東大路卓司
Original assignee: 東レ株式会社
Priority date: 2018-11-19
Filing date: 2019-11-08
Publication date: 2020-05-28
Also published as: TW202028320A; JP7375548B2; CN113056360B; KR20210092192A; CN113056360A; JPWO2020105471A1

Abstract

Provided is a biaxially oriented thermoplastic resin film, at least one surface of which satisfies the following conditions (1) and (2), and that has suitable smoothness and windability. (1) When the projection density for projections with a height of 10 nm or greater as measured by non-contact optical roughness measurement is denoted by A (projections/mm²), A is 2.0×10³ to 2.5×10⁴. (2) When the projection density for projections with a height of 1 nm or greater but less than 10 nm as measured by atomic force microscopy (AFM) is denoted by B (projections/mm²), B is 1.8×10⁶ to 1.0×10⁷.

Description

Biaxially oriented thermoplastic resin film

The present invention relates to a biaxially oriented thermoplastic resin film having coarse protrusions but fine protrusions on the background.

Thermoplastic resins are used in various industrial fields due to their good workability. Products obtained by processing these thermoplastic resins into films play an important role in today's lives such as industrial applications, optical product applications, packaging applications, and magnetic recording tape applications. 2. Description of the Related Art In recent years, electronic information devices have been downsized and highly integrated, and accordingly, films used for manufacturing electronic information devices have been required to have improved processability. In particular, in the production of electronic information devices, many methods are adopted in which another material is laminated on the film surface and the film is subjected to optical processing such as photoresist. Therefore, in order to improve the optical processability of the film, by maintaining the transparency of the film and increasing the smoothness of the film surface, the resist laser light used for processing causes light scattering due to the uneven shape of the film surface. It is a common practice to reduce this. Further, in magnetic recording tape applications, along with the increase in recording data density, it is required to increase the smoothness of the film surface to keep the distance from the reading head uniform and reduce the occurrence of error noise. Particularly in the case of coating type magnetic recording tape applications, when only one side of the film used as a support is rough, a shape transfer defect (hereinafter referred to as a transfer defect when the roll is wound onto the opposite surface (magnetic recording layer surface) side is smooth. Is caused, and the smoothness of the magnetic recording layer surface is deteriorated.

Generally, the film contains particles to ensure winding and transporting properties. By reducing the content of particles or reducing the particle size of the particles contained, the smoothness of the film can be improved and the above-mentioned transfer defects can be prevented. However, on the other hand, since there are no protrusions with high protrusions in the winding process during film manufacturing and processing, air that has become trapped between the films cannot escape and wrinkles occur in the floating portions, degrading the quality. I have something to do.

For such a problem, for example, Patent Document 1 discloses a technique of roughening the surface by using an additive without containing particles in the film.

JP, 2016-221853, A

However, when an additive is used, the surface roughness can be uniformly controlled by the content concentration of the additive, but the problem is that the smoothness is significantly reduced due to the generation of coarse foreign substances derived from the additive. become.

As a result of intensive studies by the present inventors, in order to solve the above-mentioned problems, the shape of the film surface is controlled, and projections are formed while locally having projections with a high projection height to the extent that transfer defects do not occur. It was found that coexistence of projections having a low height makes it possible to achieve both smoothness and windability (hereinafter sometimes referred to as air bleedability). In view of the above circumstances, it is an object of the present invention to provide a biaxially oriented thermoplastic resin film having good smoothness and windability.

In order to solve the above problems, the present invention has the following configurations. That is,
[I] A biaxially oriented thermoplastic resin film in which at least one surface satisfies the following (1) and (2).
(1) When the number of protrusions having a height of 10 nm or more measured by non-contact optical roughness measurement is A (pieces / mm ² ), A is 2.0 × 10 ³ or more and 2.5 × 10 ⁴ or less. To be.
(2) When the number of protrusions having a height of 1 nm or more and less than 10 nm measured by Atomic Force Microscope (AFM) is B (pieces / mm ² ), B is 1.8 × 10 ⁶ or more. It should be 1.0 × 10 ⁷ or less.
[II] The biaxially oriented thermoplastic resin film according to [I], wherein the layer constituting the surface satisfying the above (1) and (2) contains particles having an average particle diameter of 10 nm or more and 300 nm or less.
[III] When the number of protrusions having a height of 60 nm or more measured by non-contact optical roughness measurement on the surface satisfying the above (1) and (2) is C (pieces / mm ² ), C is 90. The biaxially oriented thermoplastic resin film described in [I] or [II] below.
[IV] The biaxially oriented thermoplastic resin film according to any one of [I] to [III], which is used as a release film.
[V] Dry film The biaxially oriented thermoplastic resin film according to any one of [I] to [III], which is used as a film for a resist support.
[VI] The biaxially oriented thermoplastic resin film according to any one of [I] to [III], which is used as a support film for green sheet molding in the step of producing a laminated ceramic capacitor.
[VII] The biaxially oriented thermoplastic resin film according to any one of [I] to [III], which is used as a base film for a magnetic recording medium of a coating type digital recording system.

The biaxially oriented thermoplastic resin film of the present invention has good smoothness and windability.

_R 1 nm as measured by a non-contact optical roughness measurement or AFM (Atomic Force Microscope) _measurement, R 10 _nm, is a conceptual diagram representing _{R 60 nm.} It is a schematic diagram showing one aspect | mode of 2 layer structure of the biaxially oriented thermoplastic resin film of this invention. It is a schematic diagram showing one aspect | mode of 3 layer structure of the biaxially oriented thermoplastic resin film of this invention. It is a schematic diagram showing one aspect | mode of a heterogeneous 3 layer structure of the biaxially oriented thermoplastic resin film of this invention.

The present invention will be described in detail below.

The present invention relates to a biaxially oriented thermoplastic resin film. The thermoplastic resin referred to in the present invention is a resin that exhibits plasticity when heated. Representative resins include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyethylene α, β-dicarboxylate, polymers from P-hexahydroxylylene terephthalate, polymers from 1,4 cyclohexanedimethanol, poly-P. -Polyesters having an ester bond in the main chain, represented by ethyleneoxybenzoate, polyarylate, polycarbonate, etc. and their copolymers, and further nylon 6, nylon 66, nylon 610, nylon 12, nylon 11, etc. Polyamides having an admittance in the main chain as represented, polyethylene, polypropylene, ethylene vinyl acetate copolymers, polymethylpentene, polybutene, polyisobutylene, polyolefins mainly composed of only hydrocarbons such as polystyrene. , Polyether sulfones (PES), polyphenylene oxide (PPO), polyether ether ketone (PEEK), polyethylene oxide, polypropylene oxide, polyethers represented by polyoxymethylene, polyvinyl chloride, polyvinylidene chloride, Halogenated polymers represented by polyvinylidene fluoride, polychlorotrifluoroethylene and the like, polyphenylene sulfide (PPS), polysulfone and their copolymers and modified products, polyimides and the like.

The thermoplastic resin used in the present invention preferably contains polyester, polyolefin, polyphenylene sulfide (PPS), and polyimide (PI) as main components from the viewpoint of transparency and film-forming property, and among them, polyester is particularly preferable. .. The term "main component" as used herein refers to a component that is contained in an amount of more than 50% by mass and 100% by mass or less in 100% by mass of all components of the film.

The polyester referred to in the present invention is obtained by polycondensing a dicarboxylic acid constituent component and a diol constituent component. In the present specification, the constituent component means the minimum unit that can be obtained by hydrolyzing polyester.

Examples of the dicarboxylic acid constituent component of the polyester include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 1,8-naphthalene. Examples thereof include aromatic dicarboxylic acids such as dicarboxylic acid, 4,4′-diphenyldicarboxylic acid and 4,4′-diphenyletherdicarboxylic acid, or ester derivatives thereof.

The diol constituting the polyester is ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, 1,3-butanediol. And other aliphatic diols, cyclohexanedimethanol, alicyclic diols such as spiroglycol, and a series of a plurality of the above diols. Among them, from the viewpoints of mechanical properties and transparency, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene-2,6-naphthalene dicarboxylate (PEN), and isophthalic acid as a part of the dicarboxylic acid component of PET. A polyester obtained by copolymerizing naphthalene dicarboxylic acid and a polyester obtained by copolymerizing cyclohexanedimethanol, spiroglycol, and diethyleneglycol in a part of the diol component of PET are preferably used.

The biaxially oriented thermoplastic resin film of the present invention needs to be biaxially oriented. Since the film is biaxially oriented, the mechanical strength of the film is improved and wrinkles are less likely to occur, and the winding property can be improved. The biaxial orientation referred to here is one that exhibits a biaxial orientation pattern by wide-angle X-ray diffraction. The biaxially oriented thermoplastic resin film can be generally obtained by stretching an unstretched thermoplastic resin sheet in the sheet longitudinal direction and width direction and then subjecting it to heat treatment to complete the crystal orientation. Details will be described later.

In the biaxially oriented thermoplastic resin film of the present invention, at least one surface has a number of protrusions of 10 nm or more measured by a non-contact optical roughness measuring device according to the method described later as A (pieces / mm ² ), AFM When the number of protrusions with a height of 1 nm or more and less than 10 nm measured by (Atomic Force Microscope) is B (pieces / mm ² ), A is 2.0 × 10 ³ or more and 2.5 × 10 ⁴ or less. , And B (pieces / mm ² ), B must be 1.8 × 10 ⁶ or more and 1.0 × 10 ⁷ or less (hereinafter, A is 2.0 × 10 ³ or more and 2.5 × or less). When it is 10 ⁴ or less and B (pieces / mm ² ), the film surface having B of 1.8 × 10 ⁶ or more and 1.0 × 10 ⁷ or less may be simply referred to as the surface).

The number A (number / mm ² ) of protrusions having a height of 10 nm or more measured by the non-contact optical roughness measuring device in the present invention reflects the number of protrusions responsible for air release during winding. As the number of projections A (pieces / mm ² ) increases, the area of contact with other film surfaces (hereinafter sometimes referred to as the contact area) decreases, and a space for air to escape is secured, so that the winding property is improved. Is improved. On the other hand, if the number A of projections (pieces / mm ² ) is too large, the number of high projections increases, which may increase the occurrence of transfer defects. Also, if the number of projections A (number / mm ²⁾ is small, the film is increased contact area with the other aspects by being a flat deteriorated removability air, described later projection number B (number / mm ²⁾ is No matter how many are present, wrinkles due to air left in the film at the time of winding the film may be generated to deteriorate the quality. The number A (number / mm ² ) of protrusions having a height of 10 nm or more is more preferably 3.0 × 10 ³ or more and 2.0 × 10 ⁴ or less, and further preferably 4.0 × 10 ³ or more and 2.0 × 10. It is ⁴ or less.

The number B (number / mm ² ) of protrusions having a height of 1 nm or more and less than 10 nm, which is measured by AFM (Atomic Force Microscope) in the present invention, reflects the number of fine protrusions existing in the bare surface portion of the surface. By reducing the contact area between the background portion and the other surface and increasing the escape path of air by the fine projection uneven structure, it has the effect of remarkably promoting the air release property obtained by the projections of 10 nm or more. .. In addition, since many protrusions having a height of 1 nm or more and less than 10 nm are present in the background portion, it has an effect of reducing friction between films or with a process roll and reducing scratches on the film surface. If the number of protrusions B (pieces / mm ² ) is too large, the slipperiness of the film may be improved and winding misalignment may occur during winding or during the slitter step thereafter, resulting in poor roll appearance. In addition, when the number of protrusions B (pieces / mm ² ) is small, the film becomes flat and the contact area with other surfaces increases, deteriorating air release, and air left in the film during film winding This may cause wrinkles and deteriorate the quality. The number B (number / mm ² ) of protrusions having a height of 1 nm or more and less than 10 nm is more preferably 3.0 × 10 ⁶ or more and 8.5 × 10 ⁶ or less.

In the prior art, as a method for increasing the number A (number / mm ² ) of protrusions having a height of 10 nm or more measured by a non-contact optical roughness measuring device, for example, a method of containing particles having a large particle diameter is used. Can be mentioned. Further, as a method for increasing the number B (pieces / mm ² ) of protrusions having a height of 1 nm or more and less than 10 nm measured by AFM (Atomic Force Microscope), for example, a method of containing particles having a small particle diameter can be mentioned. .. However, in such a method, by decreasing the particle diameter of the particles to be contained in order to increase the number of protrusions B, the aggregation of particles cannot be ignored, and as a result, the protrusions become coarse and the number of protrusions B decreases. Therefore, it is difficult to keep the number of protrusions B above a certain level. In the present invention, the number of protrusions A and B can be controlled within the above range by the method described later.

Further, in the biaxially oriented thermoplastic resin film of the present invention, the number C (pieces / mm ² ) of protrusions having a height of 60 nm or more measured by a non-contact optical roughness measuring instrument on the surface is 90 or less. Is preferred. The number C (number / mm ² ) of protrusions having a height of 60 nm or more reflects the number of protrusions having a height that causes a transfer defect. When the number of protrusions C (pieces / mm ² ) exceeds 90, many transfer defects occur and the smoothness of the surface opposite to the surface is reduced. Therefore, when such a film is used for magnetic tape, noise is generated. It often happens. The number of protrusions C (pieces / mm ² ) is more preferably 80 or less. The lower limit value of the number of protrusions C (pieces / mm ² ) does not particularly exist, and it is most preferable that it is ultimately 0.

In the biaxially oriented thermoplastic resin film of the present invention, the method for setting the number A of the protrusions having a height of 10 nm or more measured by a non-contact optical roughness measuring device within the above range is not particularly limited, It is possible to use a method of containing a resin or a method of containing a resin different from the film main component. From the viewpoint of forming uniform protrusions irrespective of the film forming conditions, it is preferable that particles are contained and controlled by the average particle size and content of the contained particles.

The particles contained in the biaxially oriented thermoplastic resin film of the present invention are not particularly limited, and either inorganic particles or organic particles may be used, and two or more kinds of particles may be used in combination. Examples of the inorganic particles include calcium carbonate, magnesium carbonate, zinc carbonate, titanium oxide, zinc oxide, cerium oxide, magnesium oxide, barium sulfate, zinc sulfide, calcium phosphate, alumina (α alumina, β alumina, γ alumina, δ alumina), Examples thereof include mica, mica, titanium mica, zeolite, talc, clay, kaolin, lithium fluoride, calcium fluoride, montmorillonite, zirconia, wet silica, dry silica and colloidal silica. Examples thereof include organic particles having acrylic resin, styrene resin, silicone resin, polyimide resin as a constituent component, core-shell type organic particles, and the like.

The particle size of the particles is preferably 10 nm or more and 300 nm or less in average primary particle size obtained by the method described below. When the average primary particle diameter is less than 10 nm, the cohesive force between particles becomes large, and a coarse aggregate may be formed to exceed the range of the number A of protrusions. When the average primary particle diameter exceeds 300 nm, the size of individual protrusions to be formed becomes large, which may exceed the range of the number A of protrusions. A preferable range of the average primary particle diameter of the particles is 15 nm or more and 200 nm or less.

The content of the particles contained in the biaxially oriented thermoplastic resin film of the present invention is not limited at times, but in order not to impair the transparency, the content concentration of the particles should be 3.0% by mass or less based on the entire film. Is preferred. If it exceeds 3.0% by mass, even if particles having an average primary particle size in the preferred range are used, the film may be partially clouded and the haze described below may deviate from the preferred range. It is more preferably 2.0% by mass or less, still more preferably 1.0% by mass or less. In addition, the biaxially oriented thermoplastic resin film of the present invention has a laminated constitution of two or more layers, and particles are contained only in the layer having the surface, thereby improving the transparency while aiming at the number A of projections. It becomes easy to set the range. The particle content of the layer having a surface is preferably 0.1 to 0.5 mass% with respect to the entire layer having a surface.

In addition, the biaxially oriented thermoplastic resin film of the present invention has a constitution in which the biaxially oriented thermoplastic resin film of the present invention has three or more layers from the viewpoint of further improving the winding property, and the surface is It is also preferable to adopt a mode in which particles are contained in the outermost surface layer opposite to the layer provided. Regarding the kind of particles to be contained, the same thing as the layer having the surface can be applied, but from the viewpoint of ensuring the transparency of the film, the average primary particle diameter is preferably 10 nm or more and 100 nm or less. .. The content of particles contained in the outermost layer opposite to the surface is preferably 1.5% by mass or less based on the entire outermost layer. In a more preferred embodiment, the particle content with respect to the entire biaxially oriented thermoplastic resin film is 3.0% by mass or less as described above, and the particles having the surface layer and the outermost layer on the side opposite to the surface layer are particles. Examples of the layer that does not have a surface layer while containing a film include a film that does not substantially contain particles, and such a film has good transparency.

On the surface of the biaxially oriented thermoplastic resin film of the present invention, the method for setting the number B of protrusions having a height of 1 nm or more and less than 10 nm measured by the AFM within the above range is not particularly limited, but, for example, nanoimprint As described above, there is a method of transferring the shape to the surface by using a mold, a method of subjecting an unstretched sheet to a plasma surface treatment by atmospheric pressure glow discharge, and then performing a biaxial stretching described later. From the viewpoint of in-line film forming adaptability and the number of fine projections formed, it is more preferable to perform biaxial stretching after performing plasma treatment by atmospheric pressure glow discharge. The atmospheric pressure referred to here is in the range of 700 Torr to 780 Torr.

In atmospheric pressure glow discharge treatment, a film to be treated is introduced between the opposing electrode and an earth roll, a plasma-excitable gas is introduced into the apparatus, and a high-frequency voltage is applied between the electrodes to excite the gas into plasma. Glow discharge is performed between the electrodes. In general, when treating the surface of a thermoplastic resin film by atmospheric pressure glow discharge treatment, the energy of plasma generated by glow discharge breaks the molecular chains on the film surface and vaporizes low molecular weight substances, which causes the film surface to The phenomenon of being scraped (hereinafter sometimes referred to as decomposition removal) occurs. As a result, the surface of the film is finely processed (disassembled and removed) to form protrusions.

“Plasma-excitable gas” means a gas that can be plasma-excited under the above conditions. Examples of the plasma-excitable gas include noble gases such as argon, helium, neon, krypton, and xenon, nitrogen, carbon dioxide, oxygen, or fluorocarbons such as tetrafluoromethane, and mixtures thereof. The plasma-excitable gas may be used alone or in combination of two or more kinds at any mixing ratio. From the viewpoint of high activity when excited by plasma, it preferably contains at least one of argon, oxygen and carbon dioxide, and more preferably contains oxygen. The use of a highly active plasma-excitable gas tends to accelerate the decomposition and removal of the film surface and increase the height of the protrusions formed. In some cases, the number A of protrusions having a height of 10 nm or more, which is measured by the roughness measuring device, increases.

The frequency of the high frequency voltage in the plasma treatment is preferably in the range of 1 kHz to 100 kHz. The discharge treatment strength (E value) obtained by the following method is preferably in the range of 10 to 2000 W · min / m ² from the viewpoint of projection formation, and more preferably 40 to 500 W · min / m ² . is there. If the discharge treatment strength (E value) is too low, the protrusions may not be formed sufficiently, and if the discharge treatment strength (E value) is too high, the thermoplastic resin film may be damaged, or decomposition and removal may occur. In some cases, it progresses and a preferable protrusion is not formed.
<How to obtain discharge treatment strength (E value)>
E = Vp × Ip / (S × Wt)
E: E value (W · min / m ² )
Vp: Applied voltage (V)
Ip: Applied current (A)
S: Processing speed (m / min)
Wt: Processing width (m)
FIG. 1 shows a conceptual diagram showing R _1nm , R _{10nm, and} R _60nm measured by a non-contact optical roughness measuring device and AFM. In FIG. 1, the reference plane is the height determined so that the distance from the reference plane on the measurement surface is 0 (a positive value when the distance is higher than the reference surface, a negative value when the distance is lower than the reference surface). Value).

Generally, when the surface of a thermoplastic resin film, especially a film having an amorphous part and a crystalline part such as PET or PEN, is decomposed and removed by atmospheric pressure glow discharge treatment, it is decomposed and removed from the soft amorphous part. By subdividing the crystal part and the amorphous part, it is possible to form finer projections by performing atmospheric pressure glow discharge treatment, and by increasing the crystal part, the soft amorphous part can be deeply shaved. It is possible to increase the height of the protrusion.

Therefore, the intrinsic viscosity (IV) of the layer having the surface of the thermoplastic resin film of the present invention is preferably 0.50 dl / g or more, and more preferably 0.60 dl / g or more. IV is a number that reflects the length of the molecular chain. A longer molecular chain makes it easier to clearly form a crystal part and an amorphous part in the same molecular chain. It is preferable because it becomes easier to form finer protrusions. When IV is less than 0.50 dl / g, crystallization is likely to proceed due to the short molecular chain, which may cause frequent breakage in the stretching step and make film formation difficult.

On the surface of the biaxially oriented thermoplastic resin film of the present invention, as a method of setting the number of protrusions A and B within the above range, plasma treatment was performed while the layer having the surface was made to contain the above particles. After that, biaxial stretching may be mentioned. In addition, the number A of protrusions tends to increase by nano-dispersing another thermoplastic resin component in the thermoplastic resin forming the film. Further, when the intensity of the atmospheric pressure glow discharge treatment in the plasma treatment or the activity of the plasma-excitable gas used in the atmospheric pressure glow discharge treatment is increased, the number B of the protrusions tends to increase.

The biaxially oriented thermoplastic resin film of the present invention may have a single film structure or a structure of two or more layers in which other resins are laminated. In the case of the two-layer structure, when the layer having the surface is referred to as P1 layer and the layer to be laminated is referred to as the P2 layer, the P1 layer / P2 layer structure is arranged such that the surface having the protrusion of the P1 layer is the outermost layer. Preferably. In the case of a three-layer structure, a two-kind three-layer structure (P1 layer / P2 layer / P1 layer) or a different three-layer structure in which another resin is further laminated (P1 layer / P2 layer / P3 layer) may be used. ..

The method for laminating the other resin layers such as the P1 layer, the P2 layer, and the P3 layer is not particularly limited, but the coextrusion method described below or other resin layer raw materials may be added to the extruder during film formation into the extruder. A method of laminating while melt-extruding and extruding from a die (melt-laminating method), a method of laminating films after film formation via an adhesive layer, and the like can be used. A coextrusion method capable of performing is preferably used.

The structure of the P2 layer and the P3 layer of the biaxially oriented thermoplastic resin film of the present invention is not particularly limited, but it is preferable that particles are not substantially contained from the viewpoint of ensuring the transparency of the film. The term "substantially free of particles" means that the content of particles in the thermoplastic resin is 500 ppm or less, more preferably 50 ppm or less, and most preferably 10 ppm or less. Further, in the P1, P2, and P3 layers, heat stabilizers, oxidation stabilizers, antistatic agents, organic / inorganic lubricants, nucleating agents, dyes, Additives such as a dispersant, a coupling agent, and a wavelength conversion material may be blended.

The thermoplastic resin film of the present invention preferably has a film haze of 0.60% or less when used in applications requiring high light transmittance such as films for dry film resist supports. When the haze exceeds 0.60%, transmitted light is scattered when the film is used, and for example, in a dry film resist support application, a defect occurs in the resist wiring. It is more preferably 0.50% or less, still more preferably 0.45% or less.

Next, the method for producing the thermoplastic resin film of the present invention will be described by taking a biaxially oriented polyester film as an example, but the present invention is not construed as being limited to the products obtained by such an example. ..

As a method for obtaining the polyester used in the present invention, a conventional polymerization method can be adopted. For example, a dicarboxylic acid component such as terephthalic acid or an ester-forming derivative thereof and a diol component such as ethylene glycol or an ester-forming derivative thereof are subjected to a transesterification reaction or an esterification reaction by a known method, followed by a melt polymerization reaction. It can be obtained by doing. Further, if necessary, the polyester obtained by the melt polymerization reaction may be subjected to a solid phase polymerization reaction at a melting point temperature of the polyester or lower.

The biaxially oriented thermoplastic resin film of the present invention can be obtained by a conventionally known production method. Specifically, the biaxially oriented thermoplastic resin film of the present invention is a method in which a dried raw material is heated and melted in an extruder as necessary, and extruded from a die onto a cooled cast drum to be processed into a sheet (melt casting Method) can be used. As another method, the raw material is dissolved in a solvent, and the solution is extruded from a die onto a support such as a cast drum or an endless belt to form a film, and then the solvent is dried and removed from the film layer to be processed into a sheet. A method (solution casting method) or the like can also be used.

When producing a laminated polyester film of two or more layers by a melt casting method, an extruder is used for each layer constituting the laminated polyester film, the raw materials of each layer are melted, and these are joined together between the extruder and the die. A method (co-extrusion method) of laminating in a molten state in an apparatus, guiding to a die, extruding from the die onto a cast drum and processing into a sheet (coextrusion method) is preferably used. The laminated sheet is contact-cooled and solidified by static electricity on a drum cooled to a surface temperature of 20 ° C. or higher and 60 ° C. or lower to prepare an unstretched sheet. The temperature of the cast drum is more preferably 25 ° C or higher and 60 ° C or lower, and further preferably 30 ° C or higher and 55 ° C or lower. If the temperature is 20 ° C. or less, projections may not be sufficiently formed on the film surface after being irradiated with plasma and biaxially stretched. If it exceeds 60 ° C, the film may stick to the cast drum, and it may be difficult to obtain an unstretched sheet.

Next, the unstretched film obtained here is subjected to surface treatment such as plasma treatment by atmospheric pressure glow discharge. These surface treatments may be performed immediately after obtaining the unstretched film, after slightly stretching, or after stretching in the longitudinal and / or transverse directions, but in the present invention, it is preferable to perform surface treatment on the unstretched film. Further, the surface to be surface-treated may be either the surface in contact with the cast drum (drum surface) or the surface not in contact with the cast drum (non-drum surface).

After that, the unstretched film is biaxially stretched and biaxially oriented. As a stretching method, a sequential biaxial stretching method or a simultaneous biaxial stretching method can be used. The sequential biaxial stretching method in which the film is first stretched in the longitudinal direction and then in the width direction is effective for obtaining the biaxially oriented thermoplastic film of the present invention without stretching breakage.

(Biaxial stretching)
The stretching conditions for biaxially stretching the unstretched film are not particularly limited, but when the biaxially oriented thermoplastic resin film of the present invention contains polyester as a main component, as stretching in the longitudinal direction, It is preferable that the stretched sheet is guided to a roll group heated to 70 ° C. or higher, stretched in the longitudinal direction (longitudinal direction, that is, the sheet advancing direction), and cooled by a roll group at a temperature of 20 to 50 ° C. The lower limit of the heating roll temperature in the stretching in the longitudinal direction is not particularly limited as long as the stretchability of the sheet is not impaired, but it is preferably higher than the glass transition temperature of the polyester resin used. The preferred range of the stretching ratio in the longitudinal direction is 3 to 5 times. A more preferable range is 3 to 4 times. If the stretching ratio in the longitudinal direction is less than 3 times, oriented crystallization does not proceed and the film strength is significantly reduced. On the other hand, when the stretching ratio exceeds 5 times, the oriented crystallization of the polyester resin may be accompanied by the stretching, resulting in brittleness and tearing during film formation.

Subsequently, regarding stretching in the direction perpendicular to the longitudinal direction (width direction), the film is guided to a tenter while holding both ends of the film with clips, and is perpendicular to the longitudinal direction in an atmosphere heated to a temperature of 70 to 160 ° C. It is preferable to stretch the film in a different direction (width direction) 3 to 5 times, and then heat the stretched film to stabilize the internal orientation structure. The heat history temperature received by the film during the heat treatment should be confirmed by the temperature of a minute endothermic peak (sometimes referred to as Tmeta) that appears immediately below the melting point temperature measured by a differential scanning calorimeter (DSC) described later. However, when polyester (melting point 255 ° C.) is the main component, the temperature set in the tenter is preferably set so that the maximum temperature in the tenter is 200 ° C. or higher and 250 ° C. or lower. When the main component is a plastic resin, it is preferable to set the resin melting point to −55 ° C. or lower and the resin melting point −5 ° C. or lower. When the heat treatment temperature is lower than 200 ° C., the projections formed by the atmospheric pressure glow discharge treatment cannot be sufficiently grown, and as a result, it becomes difficult to form the projections in the preferable range described above. On the other hand, when heat treatment is performed at a temperature of higher than 250 ° C., the film may be melted and frequently broken, and productivity may be reduced. A more preferable range is 220 ° C. or higher and 245 ° C. or lower.

When the polyester resin is the main component, the range of Tmeta representing the heat history temperature received by the film during the heat treatment is preferably 190 ° C. or higher and 245 ° C. or lower for the reasons described above. A more preferable range is 210 ° C. or higher and 240 ° C. or lower.
Relaxation treatment may be performed in the range of 0% to 6% for the purpose of imparting dimensional stability after further heat treatment.

The stretching ratio is 3 to 5 times in each of the longitudinal direction and the width direction, and the area ratio (longitudinal stretching ratio × horizontal stretching ratio) is preferably 9 to 22 times, more preferably 9 to 20 times. preferable. When the area ratio is less than 9 times, the durability of the obtained biaxially stretched sheet becomes insufficient, and when the area ratio exceeds 22 times, tearing tends to occur during stretching. ‥

[Characteristic evaluation method]
A. Evaluation by non-contact optical roughness measuring instrument (i) Number A of protrusions having a height of 10 nm or more (unit / mm ² ).
A sample of 10 cm × 10 cm was sampled from the biaxially oriented thermoplastic resin film of the present invention, and a non-contact optical roughness measuring device (apparatus: New View 7300 manufactured by Zygo) was used for each sample, and a 50 × objective lens was used. The measurement area was 139 μm × 104 μm, and 80 visual fields were measured by randomly changing the place. In the sample setting, the sample is set on the stage so that the measurement Y axis is in the longitudinal direction of the sample film (the longitudinal direction is the direction in which the film runs in the film manufacturing process). With respect to the obtained measurement data, the surface analysis software MetroPro 8.1.3 built in the roughness measuring instrument sets the cutoff values to 1.65 μm for High Filter Wavelen and 50.00 μm for Low Filter Wavelen. .. The Reference Band (bandwidth) is specified as 100 nm, and Peaks at the slice level of 10 nm is converted into units / mm ² . The same operation was performed in all 80 fields of view, and the average value thereof was defined as the number A (number / mm ² ) of protrusions having a height of 10 nm or more in the present invention.

(Ii) Number C of protrusions having a height of 60 nm or more (pieces / mm ² ).
Peaks at a slice level of 60 nm was converted into units / mm ² in the same manner as in the above (i), and the average value of 80 observed visual fields was defined as the number C of protrusions having a height of 60 nm or more according to the present invention.

B. Evaluation by AFM (Atomic Force Microscope) (iii) Number of protrusions B (height / mm ² ) having a height of 1 nm or more and less than 10 nm
The image of the film surface obtained by the following measurement method is analyzed using the attached analysis software (NanoScope Analysis Version 1.40). The reference plane of the film surface is automatically determined by setting the Particle Analysis analysis mode as follows after subjecting the obtained Height Sensor image of the film surface to only the Flatten process described below. From the reference plane, a numerical value obtained by converting the average value (values in Density row, Mean column) of the protrusion density per 1 μm ² per 1 mm ^{2 when} the threshold value of protrusion height (Threshold Height) is 1 nm (R _1nm ) per 1 mm ² is N _{1 nm} (number ^/ mm ^2), 10nm ^1μm 2 average protrusion density per in _{(R 10 nm)} numerical value _{N 10 nm} obtained by converting the (density row, the value of the mean column) per 1 mm ² (pieces / ^mm 2) Then, the value obtained by the following equation is defined as the number B (pieces / mm ² ) of the protrusions having a height of the measured image of 1 nm or more and less than 10 nm.
B (pieces / mm ² ) = N _{1 nm} (pieces / mm ² ) −N _{10 nm} (pieces / mm ² ).
The analysis is performed on all 20 measurement images of each sample, and the average value is defined as the number B (pieces / mm ² ) of protrusions having a height of 1 nm or more and less than 10 nm.

[AFM measurement method]
・ Device: Atomic force microscope (AFM) manufactured by Bruker
DIMENSION Icon with ScanAsyst
・ Cantilever: Silicon Nitride Probe ScanAsyst Air
・ Scan mode: ScanAsyst
・ Scanning speed: 0.977Hz
-Scanning direction: Scanning is performed in the width direction of the measurement sample manufactured by the method described later.
・ Peak Force SetPoint: 0.0195V to 0.0205V
・ Feedback Gain: 10 ~ 20
・ LP Deflection BW: 40 kHz
* ScanAyst Noise Threshold: 0.5 nm
-Sample preparation: 23 ° C, 65% RH, standing still for 24 hours-AFM measurement environment: 23 ° C, 65% RH
-Measurement sample preparation method: AFM sample disk (diameter 15 mm) with a double-sided tape attached on one side, and the AFM sample disk and the biaxially oriented thermoplastic resin of the present invention cut out into about 15 mm x 13 mm (longitudinal direction x width direction) A surface opposite to the surface (measurement surface) of the film was attached to obtain a measurement sample.

・ Sample measurement frequency: Change the location so that each sample is at least 5 μm or more, and perform 20 measurements.

-Measured value: The above-described analysis is performed on the measured 20 images, each numerical value is measured, and the average value is treated as each numerical value that the sample has.
[Flatten processing]
・ Flatten Order: 3rd
・ Flatten Z Threshholding Direction: No theresholding
・ Find Threshold for: the whole image
・ Flatten Z Threshold%: 0.00%
・ Mark Excluded Data: Yes
[Particle Analysis mode setting]
(Detect tab)
・ Threshold Height: Input according to each value ・ Feature Direction: Above
・ X Axis: Absolute
・ Number Histogram Bins: 512
・ Histogram Filter Cutoff: 0.00 nm
・ Min Peak to Peak: 1.00 nm
・ Left Peak Cutoff: 0.00000%
・ Right Peak Cutoff: 0.00000%
(Modify tab)
・ Beighbirdsize: 3
・ Number Pixels Off: 1
-Do not perform any Dilate / Erode operations.
(Select tab)
・ Image cursor mode: Particle Select
Bound Particles: Yes
・ Non-Representative Particles: No
・ Height Reference: Relative To Max Peak
・ Number Histogram Bins: 50
-When calculating the above numerical values, do not select a specific peak or area in the analysis image.
-Do not select a specific location in all histograms of Diameter, Height, and Area.

C. Average primary particle diameter The cross section of the biaxially oriented thermoplastic resin film of the present invention is observed at 10,000 times using a transmission electron microscope (TEM). At this time, when particles of 200 nm or less are confirmed in the observation visual field, the TEM observation magnification is changed to 100,000 times for observation. 100 fields of view were measured at different locations, and the equivalent circle equivalent diameters of all the dispersed particles taken in the photograph were obtained, and the equivalent circle equivalent diameter was plotted on the horizontal axis and the number distribution of particles was plotted on the vertical axis, The equivalent circle equivalent diameter of the peak value was defined as the average primary particle diameter of the particles. Here, if aggregated particles can be confirmed on the photograph observed at 10,000 times, they are not included in the above plot. When two or more kinds of particles having different particle diameters are present in the film, the number distribution of the equivalent circle equivalent diameter is a distribution having two or more peaks. In this case, each peak value is the average primary particle diameter of each particle. The particle size of the maximum particle is the particle size of the particle having the maximum particle size in the photograph observed at 10,000 times.

The average primary particle diameter of the agglomerated particles is observed at 200,000 times using the above apparatus. Agglomerated particles 10
With respect to 0 particles, the equivalent circle equivalent diameters of the individual primary particles constituting the aggregated particles are obtained and plotted by the same method as described above, and the equivalent circle equivalent diameter of the peak value is taken as the average primary particle diameter of the aggregated particles.

D. Content of Particles 1 g of P1 layer portion of the biaxially oriented thermoplastic film of the present invention was put into 200 mL of 1N-KOH methanol solution and heated under reflux to dissolve the polymer. 200 mL of water was added to the dissolved solution, and then the liquid was subjected to a centrifugal separator to settle the particles, and the supernatant was removed. Water was further added to the particles, and washing and centrifugation were repeated twice. The particles thus obtained were dried, and the content of the particles was calculated by weighing the mass.

E. Air bleeding index It was measured at 25 ° C. and 65% RH using a Digibeck smoothness tester (manufactured by Toyo Seiki Co., Ltd.). The biaxially oriented thermoplastic film of the present invention is set so that the surface having the surface is in contact with the sample table. At this time, the film is set so as to completely cover the hole formed in the sample table. In this state, a load of 1 kg / cm ² is applied to set the initial degree of reduced pressure (degree of reduced pressure from normal pressure) to 385 mmHg. After decompressing from normal pressure by 385 mmHg, air tries to return to normal pressure, so air flows in between the film and the sample stage, but at this time, the degree of pressure reduction from normal pressure to 382 mmHg to 381 mmHg (air vent time) To measure. The air bleeding time was measured for 10 samples, and the average value was used as the air bleeding index of the film.
A: Air release time is less than 2400 seconds
B: Air removal time is 2400 seconds or more and less than 2700 seconds
C: Air removal time is 2700 seconds or more and less than 2900 seconds
D: Air release time is 2900 seconds or more
A to C are good as air deficiency indexes, and A is the best.

F. Intrinsic viscosity of film IV (dL / g)
The film of the present invention is dissolved in 100 mL of orthochlorophenol (solution concentration C = 1.2 g / dL), and the viscosity of the solution at 25 ° C. is measured using an Ostwald viscometer. In addition, the viscosity of the solvent is similarly measured. Using the obtained solution viscosity and solvent viscosity, [η] (dL / g) is calculated by the following equation (a), and the obtained value is taken as the intrinsic viscosity (IV).
(A) ηsp / C = [η] + K [η] ² · C
(Here, ηsp = (solution viscosity (dL / g) / solvent viscosity (dL / g)) − 1, and K is the Huggins constant (assumed to be 0.343)).

When the biaxially oriented thermoplastic film of the present invention has a laminated structure, the IV of the layer having the surface (P1 layer) is obtained by shaving only the P1 layer by a conventional method, and measuring by the above-mentioned method.

G. Amount of terminal carboxyl group (described as COOH amount in the table)
The amount of terminal carboxyl groups was measured by the following method according to the method of Maurice. (References M. J. Maurice, F. Huizinga, Anal. Chim. Acta, 22 363 (1960)).
2 g of a measurement sample was dissolved in 50 mL of o-cresol / chloroform (mass ratio 7/3) at a temperature of 80 ° C., and titrated with a 0.05 N KOH / methanol solution to measure the terminal carboxyl group concentration, and equivalent weight / polyester 1 t It was shown by the value of. In addition, phenol red was used as an indicator at the time of titration, and the end point of the titration was determined when the color changed from yellow green to pink. If there is insoluble matter such as inorganic particles in the solution in which the measurement sample is dissolved, the solution is filtered to measure the mass of the insoluble matter, and the value obtained by subtracting the mass of the insoluble matter from the measurement sample mass is the measurement sample mass. Was corrected.

H. Winding property The biaxially oriented thermoplastic resin film of the present invention is formed into a film having a width of 4.5 m, and continuous winding of 5000 m rolls is performed 10 times. It evaluated as follows.

A: 1 roll or less with wrinkles among 10 rolls.
B: 2 rolls with wrinkles out of 10 rolls.
C: Of 10 rolls, the number of rolls with wrinkles is 3 or more and 4 or less.
D: Out of 10 rolls, the number of rolls with wrinkles is 5 or more and 6 or less.
E: Of the 10 rolls, 7 or more rolls have wrinkles.
Regarding the winding property, A to D are good, and A is the most excellent.

I. About the 10 biaxially oriented thermoplastic resin film rolls of the present invention collected in the preceding paragraph, slits are performed every 1.5 m width to collect 30 slit rolls. The winding appearance of the film roll was evaluated from the state of the slit roll as follows.

A: Of the 30 slit rolls, two or less rolls were misaligned.
B: Among the 30 slit rolls, the number of rolls in which winding deviation occurred is 3 or more and 5 or less.
C: Six or more and eight or less rolls in which the winding deviation occurred among the 30 slit rolls.
D: Out of 30 slit rolls, 9 or more rolls were misaligned.

J. Evaluation of Shape Transfer Defect The shape transfer defect of the biaxially oriented thermoplastic resin film of the present invention was evaluated by the following method. The biaxially oriented thermoplastic resin film of the present invention slit to a width of 1 m is conveyed under a tension of 200 N, and the biaxially oriented thermoplastic resin film of the present invention is provided on the side opposite to the surface for forming a non-magnetic layer described later. The coating solution and the coating solution for forming a magnetic layer are applied in multiple layers, and the coating solution for forming a backcoat layer, which will be described later, is applied to the surface side, and further slit to a width of 12.65 mm (1/2 inch) to form a pancake. create.

(Hereinafter, "part" means "part by mass".)
Coating liquid for forming magnetic layer Barium ferrite magnetic powder 100 parts (plate diameter: 20.5 nm, plate thickness: 7.6 nm,
Plate ratio: 2.7, Hc: 191 kA / m (≈2400 Oe)
Saturation magnetization: 44 Am ² / kg, BET specific surface area: 60 m ² / g)
Polyurethane resin 12 parts Weight average molecular weight 10,000
Sulfonic acid functional group 0.5 meq / g
α-alumina HIT60 (Sumitomo Chemical Co., Ltd.) 8 parts Carbon black # 55 (Asahi Carbon Co., Ltd.)
Particle size 0.015 μm 0.5 part Stearic acid 0.5 part Butyl stearate 2 parts Methyl ethyl ketone 180 parts Cyclohexanone 100 parts Non-magnetic layer forming coating liquid Non-magnetic powder α-iron oxide 100 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 Al ₂ O ₃ 8% by mass
Carbon black 20 parts "Conductex" (registered trademark) SC-U (manufactured by Columbian Carbon Co.)
Polyurethane resin UR8200 (manufactured by Toyobo Co., Ltd.) 18 parts Phenylphosphonic acid 3 parts Cyclohexanone 300 parts Methyl ethyl ketone 300 parts Butyl stearate 1 part Stearic acid 2 parts Each component of each of the above coating solutions was kneaded with a kneader. The coating solution was pumped through a horizontal sand mill containing an amount of 1.0 mmφ zirconia beads filled to 65% of the volume of the dispersion section, and the coating solution was pumped at 2,000 rpm for 120 minutes (substantially staying time in the dispersion section). ), Dispersed. Polyisocyanate was added to the resulting dispersion in an amount of 5.0 parts for the non-magnetic layer paint, 2.5 parts for the magnetic layer paint, 3 parts of methyl ethyl ketone, and a filter having an average pore size of 1 μm. It filtered using and prepared the coating liquid for nonmagnetic layer formation and the coating liquid for magnetic layer formation, respectively.

After coating the obtained coating liquid for forming a non-magnetic layer on the surface of the biaxially oriented thermoplastic resin film of the present invention opposite to the surface so as to have a thickness after drying of 0.8 μm Cobalt magnet having a magnetic force of 6,000 G (600 mT) while the magnetic layer is still in a wet state by applying the coating liquid for forming a magnetic layer so that the thickness of the magnetic layer after drying is 0.07 μm. And was oriented and dried by a solenoid having a magnetic force of 6,000 G (600 mT).
Then, a coating solution for forming a backcoat layer (carbon black average particle size: 17 nm 100 parts, calcium carbonate average particle size: 40 nm 80 parts, α-alumina average particles) so that the thickness after calendering on the surface side is 0.5 μm. Size: 200 nm 5 parts of polyurethane resin and polyisocyanate dispersed) were applied. Then, after calendering with a calender at a temperature of 90 ° C. and a linear pressure of 300 kg / cm (294 kN / m), curing was carried out at 65 ° C. for 72 hours. Furthermore, the non-woven fabric and a razor blade were attached to a device having a slitting device and a winding device so that the non-woven fabric and the razor blade were pressed against the magnetic surface, and the surface of the magnetic layer was cleaned by a tape cleaning device to obtain a magnetic tape.

The obtained tape stock was slit to a width of 12.65 mm (1/2 inch), and it was assembled in a case for LTO to create a data storage cartridge with a magnetic recording tape length of 960 m. This data storage was recorded in an environment of 23 ° C. and 50% RH using an IBM LTO7 drive (recording wavelength 0.55 μm), and then the cartridge was stored in an environment of 50 ° C. and 80% RH for 7 days. After the cartridge was stored at room temperature for one day, the full length was reproduced, and the error rate of the signal during reproduction was measured. The error rate is calculated from the error information (number of error bits) output from the drive by the following equation (b).

(A) Error rate = (error bit number) / (write bit number)
A: The error rate is less than 1.0 × 10 ⁻⁶ .

B: The error rate is 1.0 × 10 ⁻⁶ or more and less than 1.0 × 10 ⁻⁵ .

C: Error rate is 1.0 × 10 ⁻⁵ or more and less than 1.0 × 10 ⁻⁴ .

D: The error rate is 1.0 × 10 ⁻⁴ or more.
For the shape transfer defect evaluation, A to C are good, and A is the best.

K. Evaluation of green sheet characteristics a. To b. The green sheet characteristics are evaluated by the method.
a. Application of Release Layer On the surface opposite to the surface of the biaxially oriented thermoplastic film of the present invention, a crosslinked primer layer (trade name BY24-846 manufactured by Toray Dow Corning Silicone Co., Ltd.) is solid content 1% by mass. The coating solution prepared in (1) was applied / dried, and the coating thickness after drying was applied by a gravure coater and dried and cured at 100 ° C. for 20 seconds. Within 1 hour, 100 parts by mass of addition reaction type silicone resin (trade name LTC750A manufactured by Toray Dow Corning Silicone Co., Ltd.) and 2 parts by mass of platinum catalyst (trade name SRX212 manufactured by Toray Dow Corning Silicone Co., Ltd.) A coating solution adjusted to have a solid content of 5% by mass was applied by gravure coating so that the coating thickness after drying was 0.1 μm, dried and cured at 120 ° C. for 30 seconds, and then wound to obtain a release film.
b. Evaluation of application status of green sheet (applicability of ceramics slurry)
100 parts by mass of barium titanate (trade name HPBT-1 manufactured by Fuji Titanium Industry Co., Ltd.), 10 parts by mass of polyvinyl butyral (trade name BL-1 manufactured by Sekisui Chemical Co., Ltd.), 5 parts by mass of dibutyl phthalate and toluene-ethanol. (Mass ratio 30:30) Glass beads having a number average particle diameter of 2 mm were added to 60 parts by mass, mixed and dispersed by a jet mill for 20 hours, and then filtered to prepare a paste-like ceramic slurry. The obtained ceramic slurry is applied onto a surface of the release film, on which the release layer is provided in the preceding paragraph a, provided with a release layer, by a die coater so as to have a thickness of 2 μm, dried, wound, and rolled into a green sheet. Got The green sheet wound up above is unreeled and visually observed in a state where it is not peeled off from the release film to confirm the presence or absence of pinholes and the coating state of the sheet surface and the end portion. The observed area has a width of 300 mm and a length of 500 mm. The green sheet formed on the release film is illuminated with a backlight unit of 1000 lux from the back side, and pinholes due to coating loss or a recessed state due to surface transfer on the back side of the release film are observed.
A: There is no pinhole or dent.
B: There are no pinholes, and 3 or less dents are recognized.
C: There are no pinholes and 5 or less dents are recognized.
D: Some pinholes are recognized, or 6 or more dents are recognized.
A to C are good for the evaluation of green sheet characteristics, and A is the best.

L. Haze From the biaxially oriented thermoplastic film of the present invention, 3 square samples (3 pieces) each having a side of 5 cm are collected. The sample is then left for 40 hours at 23 ° C. and 60% RH. Each sample is carried out by using a turbidimeter “NDH5000” manufactured by Nippon Denshoku Industries Co., Ltd. according to a method according to JIS “How to obtain haze of transparent material” (K7136 2000 version). The haze value of each of the three points (three) is averaged to obtain the haze value of the film.

M. Photoresist Evaluation Below a. To c. The photoresist was evaluated by the method described above.
a. A negative resist “PMERN-HC600” manufactured by Tokyo Ohka Co., Ltd. is applied on a 6-inch Si wafer that has been mirror-polished on one side, and a resist layer having a thickness of 7 μm is prepared by rotating the resist with a large spinner. Then, pre-heat treatment is performed for about 20 minutes at a temperature condition of 70 ° C. using a ventilation oven with nitrogen circulation.
b. The biaxially oriented thermoplastic resin film of the present invention is laminated so that the surface opposite to the surface is in contact with the resist layer, and using a rubber roller, the biaxially oriented thermoplastic resin film is laminated on the resist layer. Then, a reticle patterned with chromium metal is arranged on the reticle, and the reticle is exposed using an I-line (ultraviolet ray having a peak wavelength of 365 nm) stepper.
c. After peeling the polyester film from the resist layer, the resist layer is placed in a container containing the developer N-A5 and development is performed for about 1 minute. Then, it is taken out from the developing solution and washed with water for about 1 minute. 30 states of L / S (μm) (Line and Space) = 10/10 μm of the resist pattern formed after development were observed with a scanning electron microscope SEM at about 800 to 3000 magnification, and the pattern was not damaged. The number is evaluated as follows.
A: The number of chips is 5 or less.
B: The number of chips is 6 or more and 10 or less.
C: The number of chips is 11 or more and 15 or less.
D: The number of chips is 16 or more.
For the photoresist evaluation, A to C are good, and A is the best.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not necessarily limited to these.

[Production of PET-1] Polymerization was performed from terephthalic acid and ethylene glycol by a conventional method using antimony trioxide as a catalyst to obtain a melt-polymerized PET containing substantially no particles. The obtained melt-polymerized PET had a glass transition temperature of 81 ° C., a melting point of 255 ° C. and an intrinsic viscosity of 0.62. Then, solid phase polymerization was carried out by a conventional method to obtain solid phase polymerized PET. The obtained solid-state polymerized PET had a glass transition temperature of 81 ° C., a melting point of 255 ° C. and an intrinsic viscosity of 0.81.

[Production of MB-A] In the polymerization of PET-1 described above, δ-alumina (alumina) having an average primary particle diameter of 21 nm dispersed in ethylene glycol so that the content in PET obtained is 2.0% by weight. -1) was added to obtain PET base master-pellet MB-A. The melt-polymerized MB-A obtained had a glass transition temperature of 81 ° C., a melting point of 255 ° C. and an intrinsic viscosity of 0.70.

[Production of MB-B] In the polymerization of PET-1 above, δ-alumina (alumina) having an average primary particle diameter of 16 nm dispersed in ethylene glycol so that the content of PET-1 obtained is 2.0% by weight. -2) was added to obtain PET base master-pellet MB-B. The obtained melt-polymerized MB-B had a glass transition temperature of 81 ° C., a melting point of 255 ° C. and an intrinsic viscosity of 0.70.

[Manufacture of MB-C] In the polymerization of PET-1 described above, δ-alumina (alumina) having an average primary particle diameter of 11 nm dispersed in ethylene glycol so that the content in PET obtained is 2.0% by weight. -3) was added to obtain PET base master pellet MB-C. The obtained melt-polymerized MB-C had a glass transition temperature of 81 ° C., a melting point of 255 ° C. and an intrinsic viscosity of 0.70.

[Production of MB-D] In the polymerization of PET-1 described above, silica (silica-containing silica having an average primary particle diameter of 210 nm dispersed in ethylene glycol so that the content of PET obtained is 2.0% by weight). 1) was added to obtain PET base master-pellet MB-D. The obtained melt-polymerized MB-D had a glass transition temperature of 81 ° C., a melting point of 255 ° C. and an intrinsic viscosity of 0.70.

[Production of MB-E] In the polymerization of PET-1 above, silica (silica-containing silica having an average primary particle diameter of 265 nm dispersed in ethylene glycol so that the content in PET obtained is 2.0% by weight). 2) was added to obtain PET base master-pellet MB-E. The obtained melt-polymerized MB-E had a glass transition temperature of 81 ° C., a melting point of 255 ° C. and an intrinsic viscosity of 0.70.

[Production of MB-F] In the polymerization of PET-1 described above, silica having an average primary particle diameter of 320 nm dispersed in ethylene glycol (silica-3 so that the content in PET obtained is 2.0%). ) Was added to obtain PET base master-pellet MB-F. The obtained melt-polymerized MB-F had a glass transition temperature of 81 ° C., a melting point of 255 ° C. and an intrinsic viscosity of 0.70.

[Production of MB-G] In the polymerization of PET-1 described above, silica (silica-containing silica having an average primary particle diameter of 72 nm dispersed in ethylene glycol so that the content of PET obtained is 2.0% by weight). 4) was added to obtain PET base master-pellet MB-G. The melt-polymerized MB-G obtained had a glass transition temperature of 81 ° C., a melting point of 255 ° C. and an intrinsic viscosity of 0.70.

[Production of MB-H] In the polymerization of PET-1 described above, silica dispersed in ethylene glycol having an average primary particle diameter of 370 nm (silica-based so that the content in PET obtained is 2.0% by weight). 5) was added to obtain PET base master-pellet MB-H. The obtained melt-polymerized MB-H had a glass transition temperature of 81 ° C., a melting point of 255 ° C. and an intrinsic viscosity of 0.70.

[Production of MB-I] The content of PET-1 and sodium stearate (crystal nucleating agent-1) in the content of sodium stearate (crystal nucleating agent-1) is 5.0% by weight based on PET-1. Twin-screw kneading extrusion was performed to obtain PET base master pellets MB-I. The obtained melt-polymerized MB-I had a glass transition temperature of 83 ° C., a melting point of 255 ° C. and an intrinsic viscosity of 0.65.

(Example 1)
PET-1 and master pellet MB-A were dried under reduced pressure at 180 ° C. for two and a half hours, and then compounded so that the particle content concentration would be the amounts of P1 layer and P2 layer shown in Table 1, and added to each extruder. After being supplied, melt-extruded and filtered with a filter, they are joined so as to be laminated with P1 layer / P2 layer in a feed block, and then electrostatically cast method is applied on a cooling roll kept at 37 ° C through a T die. It was wound around and solidified by cooling to obtain an unstretched film. This unstretched film was introduced between the opposing electrode and an earth roll, nitrogen gas was introduced into the apparatus, and atmospheric pressure glow discharge treatment was performed under the condition that the E value was 160 W · min / m ² .
The unstretched film after the treatment was sequentially stretched by a biaxial stretching machine under the conditions shown in Tables 1 and 2 by a stretching ratio of 3.6 times in the longitudinal direction and 4.0 times in the width direction, for a total of 14.4 times. Then, it heat-processed at 240 degreeC under fixed length. Then, relaxation treatment was applied in the width direction to obtain a biaxially oriented film having a thickness of 4.5 μm. Tables 3 and 4 show the physical properties, surface projection shape and characteristic evaluation of the obtained biaxially oriented film. The film had good winding properties, winding appearance, and transfer defects.

(Example 2-4)
In Example 2-4, a biaxially oriented film having a thickness of 4.5 μm was obtained in the same manner as in Example 1 except that the master pellet used was changed to have the particle content concentration shown in Table 1. Tables 3 and 4 show the physical properties, surface projection shape and characteristic evaluation of the obtained biaxially oriented film.

In Example 2, when a large amount of particles having an average primary particle diameter of 250 nm, which is larger than that in Example 1, was added, the number of protrusions having a height of 10 nm or more measured by non-contact optical roughness measurement increased. The transfer defect was lower than that in Example 1, but was within the practical range, and the film was good in winding property and winding deviation.

In Examples 3 and 4, when particles having an average primary particle diameter of 15 nm and 10 nm, which are smaller than those in Example 1, were used, the number of protrusions having a height of 10 nm or more measured by non-contact optical roughness measurement decreased. The winding property was worse than that of Example 1, and the number of protrusions having a height of 1 nm or more and less than 10 nm measured by AFM was increased and the winding appearance was worse than that of Example 1 due to winding misalignment. And the transfer defect was a good film.

(Example 5)
In Example 5, a biaxially oriented film having a thickness of 4.5 μm was obtained in the same manner as in Example 1 except that the atmospheric pressure glow discharge treatment was performed under the condition that the E value was 450 W · min / m ² as shown in Table 2. It was Tables 3 and 4 show the physical properties, surface projection shape and characteristic evaluation of the obtained biaxially oriented film.
In comparison with Example 1, Example 5 has an increase in the number of protrusions having a height of 1 nm or more and less than 10 nm measured by AFM, which is within the practical range although the winding shape deteriorates due to winding deviation, and the winding property is improved. The transfer defect was a good film.

(Examples 6 and 7)
Examples 6 and 7 were the same as Example 1 except that the master pellets used were changed to have the particle addition concentrations shown in Table 1 and the atmospheric pressure glow discharge treatment was changed as shown in Table 2. As a result, a biaxially oriented film having a thickness of 4.5 μm was obtained. Tables 3 and 4 show the physical properties, surface projection shape and characteristic evaluation of the obtained biaxially oriented film.
In Examples 6 and 7, the number of protrusions having a height of 1 nm or more and less than 10 nm measured by AFM was smaller than that in Example 1. In Example 6, the number of protrusions having a height of 10 nm or more measured by the non-contact optical roughness measurement was the same as that in Example 1, and the winding property was worse than that of Example 1 although it was within the practical range. On the other hand, in Example 7, the number of protrusions having a height of 10 nm or more measured by the non-contact optical roughness measurement was larger than that in Example 1, and thus the winding property was as good as in Example 1. However, the transfer defect was worse than that of Example 1 within the range of practical use.

(Examples 8 and 9)
In Examples 8 and 9, a biaxially oriented film having a thickness of 4.5 μm was obtained in the same manner as in Example 1, except that the master pellet used was changed to have the particle addition concentration shown in Table 1. Tables 3 and 4 show the physical properties, surface projection shape and characteristic evaluation of the obtained biaxially oriented film.
In each of Examples 8 and 9, the number of protrusions having a height of 10 nm or more measured by the non-contact optical roughness measurement and the number of protrusions having a height of 1 nm or more and less than 10 nm measured by AFM are in the preferable ranges. By using particles having large particle diameters of 200 nm and 300 nm, the number of protrusions having a height of 60 nm or more measured by non-contact optical roughness measurement increased as compared with Example 1. As a result, although the transfer defects of Examples 8 and 9 were worse than those of Example 1, they were within the practical range, and the films had good winding properties.

(Example 10)
A biaxially oriented film was obtained in the same manner as in Example 3 except that the gas species used in the atmospheric pressure glow discharge treatment was a gas obtained by mixing 0.5% by volume of oxygen gas with nitrogen gas. The physical properties, surface projection shape and property evaluation of the obtained biaxially oriented film are as shown in Tables 3 and 4.
Since the plasma-excitable gas with high activity was used in Example 10, the number A of protrusions increased as compared with Example 3 due to an increase in the size of the protrusions derived from the added particles, and a film having good winding properties and transfer defects. Became.

(Example 11)
A biaxially oriented film was obtained in the same manner as in Example 1 except that the film thickness was 25 μm. The physical properties, surface projection shape and property evaluation of the obtained biaxially oriented film are as shown in Tables 3 and 4. The film of Example 11 was as good as that of Example 1 in terms of winding property, winding shape, and transfer defect.
When the green sheet evaluation and the photoresist evaluation were performed on the film of Example 11 by the method described above, the haze slightly increased as compared with Example 1 due to an increase in the film thickness, but both were good as shown in Tables 5 and 6. These results can be suitably used as a film for a dry film resist support or a film for a green sheet molding support.

(Example 12)
Except that each layer was extruded with the composition shown in Table 1 by using three kinds of extruders and laminated so as to have a different three-layer constitution of P1 layer / P2 layer / P3 layer, and the film thickness was 25 μm. A biaxially oriented film was obtained in the same manner as in 1. The physical properties, surface projection shape and property evaluation of the obtained biaxially oriented film are as shown in Tables 3 and 4. In Example 12, a film having good winding appearance and transfer defects as in Example 1 was obtained, and further, by providing a P3 layer containing particles on the outermost surface opposite to the surface, the winding property was improved. It was a film superior to 1.
When the green sheet evaluation and the photoresist evaluation were performed on the film of Example 12 by the method described above, the photoresist evaluation was lowered because the haze was increased as compared with Example 11 by providing the P3 layer containing particles. However, it is within the practical range, and can be suitably used as a film for a dry film resist support or a film for a green sheet support.

(Comparative Example 1)
After obtaining an unstretched film in the same manner as in Example 1, a biaxially oriented film was obtained in the same manner as in Example 1 except that the unstretched film was sequentially introduced into a biaxial stretching machine without performing atmospheric pressure glow discharge treatment. Obtained. The physical properties, surface projection shape and property evaluation of the obtained biaxially oriented film are as shown in Tables 3 and 4.
Since the atmospheric pressure glow discharge treatment was not carried out, the number of protrusions having a height of 1 nm or more and less than 10 nm measured by AFM was significantly reduced, and as a result, the film was significantly inferior in windability.

(Comparative example 2)
A biaxially oriented film was obtained in the same manner as in Example 1 except that the P1 layer contained substantially no particles. The physical properties, surface projection shape and property evaluation of the obtained biaxially oriented film are as shown in Tables 3 and 4.
Since particles are not added, protrusions are efficiently formed on the background, and the number of protrusions with a height of 1 nm or more and less than 10 nm measured by AFM increases, but measured by non-contact optical roughness measurement. The number of projections having a height of 10 nm or more was significantly reduced, and the winding property was lowered, and as a result, the film was significantly inferior in the winding property.

(Comparative example 3)
A biaxially oriented film was obtained in the same manner as in Example 1 except that the average primary particle diameter of the particles added from Example 1 was 350 nm as shown in Table 1. The physical properties, surface projection shape and property evaluation of the obtained biaxially oriented film are as shown in Tables 3 and 4.
By using the large-diameter particles, the number of protrusions having a height of 10 nm or more measured by the non-contact optical roughness measurement was significantly increased, and as a result, the transfer defect was significantly deteriorated.

(Comparative example 4)
PET-1 as a raw material for the P1 layer and sodium stearate (crystal nucleating agent-1) which is a crystal nucleating agent were mixed in the amounts shown in Table 1, and the two were sequentially added without performing atmospheric pressure glow discharge treatment. A biaxially oriented film was obtained in the same manner as in Example 1 except that the biaxially oriented film was introduced into the axial stretching machine. Tables 4 and 5 show the physical properties, surface projection shape and characteristic evaluation of the obtained biaxially oriented film.
In Comparative Example 4, by adding the crystal nucleating agent, the number of protrusions having a height of 1 nm or more and less than 10 nm measured by AFM was significantly reduced as compared with Example 1, and the winding property was significantly deteriorated.

(Comparative example 5)
A biaxially oriented film was obtained in the same manner as in Comparative Example 1 except that the film thickness was 25 μm. The physical properties, surface projection shape, and characteristic evaluation of the obtained biaxially oriented film are as shown in Tables 3 and 4. Comparative Example 5 was a film in which the winding property was significantly inferior to that of Comparative Example 1. When the green sheet evaluation and the photoresist evaluation were performed on the film of Comparative Example 5 by the method described above, wrinkles and scratches were generated on the film surface due to poor winding property and the haze of the film was increased. As a result, as shown in Tables 5 and 6, the green sheet evaluation and the photoresist evaluation were significantly deteriorated.

The thermoplastic resin film of the present invention has good transparency, smoothness, and slipperiness, and can further improve scratch resistance in the film forming / processing step. It can be suitably used as a dry film resist support polyester film, an optical device substrate film, a ceramic capacitor release film, or a magnetic recording medium film to be used.

1. Layer that has been processed to form protrusions (P1 layer)
2. Reference plane (height 0 nm) for non-contact optical roughness measurement and AFM measurement
3. Height 1nm line (R _1nm )
4. Height 10nm line (R _10nm )
5. Height 60nm line (R _60nm )
6. P2 layer 7. P3 layer

Claims

A biaxially oriented thermoplastic resin film in which at least one surface satisfies the following (1) and (2).
(1) When the number of protrusions having a height of 10 nm or more measured by non-contact optical roughness measurement is A (pieces / mm 2 ), A is 2.0 × 10 3 or more and 2.5 × 10 4 or less. To be.
(2) When the number of protrusions having a height of 1 nm or more and less than 10 nm measured by Atomic Force Microscope (AFM) is B (pieces / mm 2 ), B is 1.8 × 10 6 or more. It should be 1.0 × 10 7 or less.
The biaxially oriented thermoplastic resin film according to claim 1, wherein the layer constituting the surface satisfying the above (1) and (2) contains particles having an average particle diameter of 10 nm or more and 300 nm or less.
When the number of protrusions having a height of 60 nm or more measured by non-contact optical roughness measurement on the surface satisfying the above (1) and (2) is C (pieces / mm 2 ), C is 90 or less. The biaxially oriented thermoplastic resin film according to claim 1 or 2.
The biaxially oriented thermoplastic resin film according to any one of claims 1 to 3, which is used as a release film.
The biaxially oriented thermoplastic resin film according to any one of claims 1 to 3, which is used as a film for a dry film resist support.
The biaxially oriented thermoplastic resin film according to any one of claims 1 to 3, which is used as a film for a support for green sheet molding in a process for producing a monolithic ceramic capacitor.
The biaxially oriented thermoplastic resin film according to any one of claims 1 to 3, which is used as a base film for a magnetic recording medium of a coating type digital recording system.