WO2022131008A1

WO2022131008A1 - Polyester film, dry film resist, and method for producing polyester film

Info

Publication number: WO2022131008A1
Application number: PCT/JP2021/044298
Authority: WO
Inventors: 一仁宮宅; 悠樹豊嶋; 泰雄江夏
Original assignee: 富士フイルム株式会社
Priority date: 2020-12-17
Filing date: 2021-12-02
Publication date: 2022-06-23
Also published as: JPWO2022131008A1; CN116601567A

Abstract

The present invention addresses the problem of providing a polyester film for optical use, which has excellent anti-scratch properties, and can be used for the production of such a dry film resist that, when a high-precise resist pattern is formed using the dry film, the resist pattern has excellent pattern linearity. The present invention also addresses the problem of providing: a dry film resist; and a method for producing a polyester film.　The polyester film according to the present invention is a polyester film for optical use, which comprises a polyester base material containing substantially no particle and a particle-containing layer arranged on at least one surface of the polyester base material and comprising particles and a resin, and which has a first main surface and a second main surface, in which the second main surface is a surface opposed to a polyester base material side of the particle-containing layer, the maximum cross-section height SRt of the second main surface is 20 to 150nm, and the thickness of the particle-containing layer is 1 to 200 nm.

Description

Method for manufacturing polyester film, dry film resist, polyester film

The present invention relates to a polyester film, a dry film resist, and a method for producing a polyester film.

Polyester films are used in a wide range of applications from the viewpoints of processability, mechanical properties, electrical properties, dimensional stability, transparency, chemical resistance, etc. For example, dry film resist supports and protective films. It is used as. The dry film resist has, for example, a structure in which a photosensitive resin layer (photoresist layer) is laminated on a support, and then a protective film is further laminated. In recent years, dry film resists have been used in the field of touch panels for etching in the wiring forming process, for forming a protective film for protecting wiring portions such as copper, ITO (indium tin oxide) and silver nanoparticles, and for interlayer insulating films. It is used for various purposes.

Patent Document 1 describes a laminated polyester film in which a polyester film is used as a support and a resist layer is provided on one side of the support, and the haze of the laminated film is 1.0% or less, and the resist layer side of the laminated film is provided. Disclosed is a polyester film for ultrafine wire photoresist in which the surface on the opposite side has a predetermined surface intrinsic resistance and abrasion resistance index, and the number of scratches on the surface is less than a predetermined value.

Japanese Unexamined Patent Publication No. 2006-327158

Conventionally, particles are contained on the surface of a polyester film for the purpose of preventing the films from coming into close contact with each other and being scratched when a laminate such as the dry film resist (DFR) is manufactured using a polyester film as a support. A technique for providing a surface layer is known.
On the other hand, with the recent increase in resolution (finening) of resist patterns, the performance (thin film, low haze, etc.) that can contribute to higher resolution of resist patterns for the supports constituting DFR is higher than before. High performance is required.
With reference to the technique described in Patent Document 1, the present inventors used a DFR having a polyester film containing particles as a support, and used a fine resist pattern having a narrower pattern width (particularly L of 10 μm or less). / S pattern) was formed, and it was found that the pattern linearity of the resist pattern may be lowered depending on the characteristics of the polyester film.

In view of the above circumstances, the present invention is excellent in scratch resistance, and by using it in the production of a dry film resist, the pattern linearity is formed even when a high-definition resist pattern is formed using the dry film. It is an object of the present invention to provide a polyester film capable of forming an excellent resist pattern.
Another object of the present invention is to provide a method for producing a dry film resist and a polyester film.

As a result of diligent studies on the above problems, the present inventors have found that the above problems can be solved by the following configuration.

[1]
A polyester substrate containing substantially no particles and a particle-containing layer containing particles and a resin arranged on at least one surface of the polyester substrate are provided, and the first main surface and the second main surface are provided. The second main surface is a surface of the particle-containing layer opposite to the polyester base material side, and the maximum cross-sectional height SRt of the second main surface is 20. A polyester film having a particle thickness of about 150 nm and a thickness of the particle-containing layer of 1 to 200 nm.
[2]
The polyester film according to [1], which is a polyester film for producing a dry film resist.
[3]
The polyester film according to [2], wherein the surface free energy of the second main surface is 50 mJ / m ² or less.
[4]
The polyester film according to [2] or [3], wherein the resin contains an acrylic resin.
[5]
The polyester film according to [4], wherein the acrylic resin is a copolymer having a structural unit derived from styrene and a structural unit derived from (meth) acrylate.
[6]
The acrylic resin has a structural unit derived from (meth) acrylate having an unsubstituted alkyl group having 1 to 4 carbon atoms in the ester moiety and an unsubstituted alkyl group having 5 to 10 carbon atoms in the ester moiety (meth). ) The polyester film according to [4] or [5], which has a structural unit derived from acrylate.
[7]
The polyester film according to any one of [1] to [6], wherein the polyester film has a thickness of 1 to 35 μm.
[8]
The polyester film according to any one of [1] to [7], wherein the maximum cross-sectional height SRt of the second main surface is 20 to 40 nm.
[9]
The product (D × SRt) of the density D (unit: piece / μm ² ) of the particles constituting the protrusions on the second main surface and the maximum cross-sectional height SRt (unit: nm) of the second main surface. The polyester film according to any one of [1] to [8], wherein the polyester film is 600 or less.
[10]
The polyester film according to any one of [1] to [9], wherein the particle-containing layer further contains a hydrocarbon-based surfactant.
[11]
The polyester film according to any one of [1] to [10], wherein the resin has a crosslinked structure.
[12]
The polyester film according to any one of [1] to [11], wherein the particle-containing layer further contains wax.
[13]
The polyester film according to any one of [1] to [12], wherein the maximum cross-sectional height SRt of the first main surface is 5 to 40 nm.
[14]
The surface average roughness SRa of the first main surface is 0 to 5.0 nm, and the surface average roughness SRa of the second main surface is 1.0 to 5.0 nm, [1] to [13]. ] The polyester film described in any of.
[15]
The polyester film according to any one of [1] to [14], wherein the surface free energy of the first main surface is 50 to 70 mJ / m ² .
[16]
A dry film resist comprising the polyester film according to any one of [1] to [15] and a photosensitive resin layer provided on the first main surface of the polyester film.
[17]
The dry film resist according to [16], wherein the photosensitive resin layer contains a polymer, a polymerizable compound, and a photopolymerization initiator.
[18]
A step of in-line coating a polyester base material containing substantially no particles with a composition for forming a particle-containing layer containing particles and a resin to form a particle-containing layer is provided, and the above-mentioned particle-containing layer is formed. The method for producing a polyester film according to any one of [1] to [15], wherein the average particle size of the particles dispersed in the forming composition is 10 to 250 nm.

According to the present invention, a resist pattern excellent in scratch prevention and excellent in pattern linearity even when a high-definition resist pattern is formed by using the dry film resist in the production of a dry film resist. Can provide an optical polyester film capable of forming.
Further, according to the present invention, it is possible to provide a method for producing a dry film resist and a polyester film.

It is sectional drawing which shows an example of the structure of the polyester film which concerns on this disclosure.

Hereinafter, embodiments of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be carried out with appropriate modifications within the scope of the object of the present invention.

In the present disclosure, the numerical range represented by using "-" means a range including the numerical values before and after "-" as the lower limit value and the upper limit value. In the numerical range described stepwise in the present disclosure, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in another stepwise description. Further, in the numerical range described in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples.
In the present disclosure, the amount of each component in the composition means the total amount of the plurality of substances present in the composition when a plurality of substances corresponding to each component are present in the composition, unless otherwise specified. ..
In the present disclosure, the term "process" is included in this term not only as an independent process but also as long as the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes. ..
In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment.

In the present disclosure, the description of a mere "polyester film" includes both a polyester base material alone and a laminate of a polyester base material and a particle-containing layer.
In the present disclosure, the "longitudinal direction" means the elongated direction of the polyester film at the time of manufacturing the polyester film, and is synonymous with the "transport direction" and the "mechanical direction".
In the present disclosure, the "width direction" means a direction orthogonal to the longitudinal direction. In the present disclosure, "orthogonal" is not limited to strict orthogonality, but includes substantially orthogonality. "Approximately orthogonal" means intersecting at 90 ° ± 5 °, preferably at 90 ° ± 3 °, and more preferably at 90 ° ± 1 °.
Further, in the present disclosure, the "film width" means the distance between both ends of the polyester film in the width direction.

In the present disclosure, "(meth) acrylate" represents at least one of acrylate and methacrylate, "(meth) acrylic acid" represents at least one of acrylic acid and methacrylic acid, and "(meth) acrylic" represents acrylic and methacrylic. Represents at least one.

Further, in the present specification, "exposure" includes not only exposure using light but also drawing using particle beams such as an electron beam and an ion beam, unless otherwise specified. Examples of the light used for exposure include emission line spectra of mercury lamps, far ultraviolet rays typified by excima lasers, extreme ultraviolet rays (EUV light), X-rays, and active rays (active energy rays) such as electron beams. ..

[Polyester film]
The polyester film according to the present disclosure (hereinafter, also referred to as “the film”) is a polyester base material containing substantially no particles, and particles and a resin arranged on at least one surface of the polyester base material. An optical polyester film comprising a particle-containing layer containing the particles (hereinafter, also referred to as a “specific layer”) and having a first main surface and a second main surface.
Further, in this film, the second main surface is the surface opposite to the polyester base material side of the specific layer, the maximum cross-sectional height SRt of the second main surface is 20 to 150 nm, and the thickness of the specific layer is It is 1 to 200 nm.

〔Constitution〕
The structure of this film will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing an example of the configuration of this film. The polyester film 1 includes a polyester base material 2 and a specific layer 3 having a specific thickness arranged on at least one surface of the polyester base material 2, and has a first main surface 1a and a second main surface 1b. Have.
The specific layer 3 contains particles (not shown), while the polyester substrate 2 contains substantially no particles.

As shown in FIG. 1, the two surfaces of the polyester film 1 are referred to as a first main surface 1a and a second main surface 1b.
Of these, the second main surface 1b is the surface of the specific layer 3 opposite to the surface facing the polyester base material 2. That is, the specific layer 3 is the outermost layer of the polyester film 1. The second main surface 1b has the above-mentioned specific maximum cross-sectional height SRt.

By having the above structure, this film is excellent in scratch prevention, and even when used for forming a finer resist pattern, polyester can produce a dry film resist having excellent pattern linearity of the resist pattern. It has the effect of being able to provide a film (hereinafter, at least one of these effects is also referred to as "the effect of the present invention").
The reason why this film exerts the above-mentioned effect of the present invention is not clear, but it is presumed as follows.

As described above, the polyester film for DFR production often contains particles for the purpose of improving the scratch prevention property during DFR production.
However, according to the study by the present inventors, a case where a photosensitive resin layer is formed on the surface of a polyester film containing particles to produce a DFR, and the obtained DFR is used to form a fine resist pattern. , The particles contained in the polyester film and / or the transfer marks formed by the particles transferring the uneven structure formed on the surface of the polyester film to the photosensitive resin layer scatter the irradiation light at the time of pattern exposure. Therefore, it is presumed that the pattern linearity may decrease.
On the other hand, in this film, by adopting a polyester base material that substantially contains no particles as the base material constituting the polyester film, the scattering of the pattern exposure by the particles is suppressed and the photosensitive material laminated on the polyester film is photosensitive. It is presumed that the scattering of the pattern exposure can be suppressed by reducing the transfer marks formed on the sex resin layer. Further, on the surface (second main surface) of the film on the side where the photosensitive resin layer is not laminated, a particle-containing layer having a thin thickness and having a maximum cross-sectional height SRt suppressed to a specific value or less is formed. Therefore, it is possible to suppress the scattering of the pattern exposure on the surface of the particle-containing layer. It is considered that a resist pattern having high definition and excellent pattern linearity can be formed by suppressing scattering during pattern exposure by the above-mentioned characteristic structure of this film.
Further, in this film, since the maximum cross-sectional height SRt of the particle-containing layer is equal to or higher than a specific value, the slipperiness is lowered and the films are easily adhered to each other to suppress the generation of scratches and the particle-containing layer. Since the maximum cross-sectional height SRt of S Be done.
Hereinafter, with respect to a polyester film, even when a DFR is produced using the polyester film and a high-definition resist pattern is further formed using the DFR, a characteristic that a resist pattern having excellent pattern linearity can be formed. Is simply described as "excellent in pattern linearity".

The present film has the above polyester base material and the above specific layer, and the specific embodiment thereof is particularly limited as long as the maximum cross-sectional height SRt of the second main surface is specified in the above range. However, it may have an embodiment other than the configuration shown in FIG.
For example, in the configuration shown in FIG. 1, the first main surface 1a of the polyester film 1 is a surface opposite to the specific layer 3 side of the polyester base material 2, but is opposite to the specific layer side of the polyester base material 2. On the surface of the above, another layer may be arranged in which one surface is the first main surface. Examples of such other layers include an adhesion layer, a peeling layer, an antistatic layer, and an oligomer precipitation prevention layer.
Further, in the configuration shown in FIG. 1, the specific layer 3 is arranged on only one side of the polyester base material 2, but may be arranged on both sides.
Further, in the configuration shown in FIG. 1, the specific layer 3 is arranged in contact with the surface of the polyester base material 2, but an intermediate layer such as a primer layer may be provided between the specific layer and the polyester base material. ..
The thickness of the other layers is preferably 1 nm to 1 μm, more preferably 30 to 500 nm.

Hereinafter, each layer of this film will be described in detail.

<Polyester base material>
The polyester base material is a film-like object containing polyester as a main polymer component. Here, the "main polymer component" means the polymer having the highest content (mass) among all the polymers contained in the film.
The polyester base material may contain one kind of polyester alone or may contain two or more kinds of polyesters.

(polyester)
Polyester is a polymer having an ester bond in the main chain. Polyester is usually formed by polycondensing a dicarboxylic acid compound and a diol compound, which will be described later.
The polyester is not particularly limited, and known polyesters can be used. Examples of the polyester include polyethylene terephthalate (PET), polyethylene-2,6-naphthalate (PEN), and copolymers thereof, and PET is preferable.

The intrinsic viscosity of the polyester is preferably 0.50 dl / g or more and less than 0.80 dl / g, and more preferably 0.55 dl / g or more and less than 0.70 dl / g.
The melting point (Tm) of the polyester is preferably 220 to 270 ° C, more preferably 245 to 265 ° C.
The glass transition temperature (Tg) of polyester is preferably 65 to 90 ° C, more preferably 70 to 85 ° C.

The method for producing polyester is not particularly limited, and a known method can be used. For example, polyester can be produced by polycondensing at least one dicarboxylic acid compound and at least one diol compound in the presence of a catalyst.

-catalyst-
The catalyst used for producing the polyester is not particularly limited, and a known catalyst that can be used for synthesizing the polyester can be used.
Examples of the catalyst include alkali metal compounds (for example, potassium compounds and sodium compounds), alkaline earth metal compounds (for example, calcium compounds and magnesium compounds), zinc compounds, lead compounds, manganese compounds, cobalt compounds, aluminum compounds, and antimony. Examples include compounds, titanium compounds, germanium compounds, and phosphorus compounds. Of these, titanium compounds are preferable from the viewpoint of catalytic activity and cost.
Only one kind of catalyst may be used, or two or more kinds of catalysts may be used in combination. At least one metal catalyst selected from potassium compounds, sodium compounds, calcium compounds, magnesium compounds, zinc compounds, lead compounds, manganese compounds, cobalt compounds, aluminum compounds, antimony compounds, titanium compounds, and germanium compounds, and phosphorus compounds. It is preferable to use in combination with, and it is more preferable to use a titanium compound and a phosphorus compound in combination.

As the titanium compound, an organic chelated titanium complex is preferable. The organic chelated titanium complex is a titanium compound having an organic acid as a ligand.
Examples of the organic acid include citric acid, lactic acid, trimellitic acid, and malic acid.
As the titanium compound, the titanium compound described in paragraphs 0049 to 0053 of Japanese Patent No. 5575671 can also be used, and the contents of the above publication are incorporated in the present specification.

-Dicarboxylic acid compound-
Examples of the dicarboxylic acid compound include dicarboxylic acids such as aliphatic dicarboxylic acid compounds, alicyclic dicarboxylic acid compounds, and aromatic dicarboxylic acid compounds, and dicarboxylic acids such as methyl ester compounds and ethyl ester compounds of the dicarboxylic acids. Esther can be mentioned. Of these, aromatic dicarboxylic acid or methyl aromatic dicarboxylic acid is preferable.

Examples of the aliphatic dicarboxylic acid compound include malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecandic acid, dimer acid, eicosandionic acid, pimelic acid, azelaic acid, and methylmalonic acid. And ethylmalonic acid.
Examples of the alicyclic dicarboxylic acid compound include adamantandicarboxylic acid, norbornnedicarboxylic acid, cyclohexanedicarboxylic acid, and decalindicarboxylic acid.

Examples of the aromatic dicarboxylic acid compound include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 1,8-naphthalenedicarboxylic acid. , 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 5-sodium sulfoisophthalic acid, phenylindandicarboxylic acid, anthracendicarboxylic acid, phenanthrangecarboxylic acid, and 9,9'-bis (4-carboxy). Examples include phenyl) fluorenic acid and their methyl ester forms.
Of these, terephthalic acid, methyl terephthalate, 2,6-naphthalenedicarboxylic acid, or methyl 2,6-naphthalenedicarboxylic acid is preferable, and terephthalic acid or methyl terephthalate is more preferable.

Only one type of dicarboxylic acid compound may be used, or two or more types may be used in combination. When terephthalic acid is used as the dicarboxylic acid compound, terephthalic acid may be used alone, or may be copolymerized with another aromatic dicarboxylic acid such as isophthalic acid or an aliphatic dicarboxylic acid.

-Glycol compound-
Examples of the diol compound include an aliphatic diol compound, an alicyclic diol compound, and an aromatic diol compound, and an aliphatic diol compound is preferable.

Examples of the aliphatic diol compound include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, 1,3-butanediol, and neo. Examples include pentyl glycol, preferably ethylene glycol.
Examples of the alicyclic diol compound include cyclohexanedimethanol, spiroglycol, and isosorbide.
Examples of the aromatic diol compound include bisphenol A, 1,3-benzenedimethanol, 1,4-benzenedimethanol, and 9,9'-bis (4-hydroxyphenyl) fluorene.
Only one kind of diol compound may be used, or two or more kinds may be used in combination.

-End sealant-
In the production of polyester, an end-capping agent may be used if necessary. By using the end sealant, a structure derived from the end sealant is introduced into the end of the polyester.
As the terminal encapsulant, a known end encapsulant can be used without limitation. Examples of the terminal encapsulant include oxazoline compounds, carbodiimide compounds, and epoxy compounds.
As the terminal encapsulant, the contents described in paragraphs 0055 to 0064 of JP-A-2014-189002 can also be referred to, and the contents of the above-mentioned publication are incorporated in the present specification.

-Manufacturing conditions-
The reaction temperature is not limited and may be appropriately set according to the raw material. The reaction temperature is preferably 260 to 300 ° C, more preferably 275 to 285 ° C.
The pressure is not limited and may be appropriately set according to the raw material. The pressure is preferably 1.33 × 10 ^-3 to 1.33 × 10 ^-5 MPa, more preferably 6.67 × 10 ^-4 to 6.67 × 10 ^-5 MPa.

As a method for synthesizing polyester, the methods described in paragraphs 0033 to 0070 of Japanese Patent No. 5575671 can also be used, and the contents of the above publication are incorporated in the present specification.

The polyester content in the polyester base material is preferably 85% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, still more preferably 98% by mass, based on the total mass of the polymer in the polyester base material. The above is particularly preferable.
The upper limit of the polyester content is not limited and can be appropriately set within a range of 100% by mass or less with respect to the total mass of the polymer in the polyester substrate.

When the polyester substrate contains polyethylene terephthalate, the content of polyethylene terephthalate is preferably 90 to 100% by mass, more preferably 95 to 100% by mass, and 98 to 100% by mass, based on the total mass of the polyester in the polyester substrate. 100% by mass is more preferable, and 100% by mass is particularly preferable.

The polyester substrate may contain components other than polyester (eg, catalyst, unreacted raw material components, particles, water, etc.).
From the viewpoint of excellent pattern linearity, the polyester base material contains substantially no particles. Examples of the particles include particles contained in a specific layer described later. In addition, "substantially free of particles" means that the content of particles is 50 with respect to the total mass of the polyester substrate when the elements derived from the particles are quantitatively analyzed by fluorescent X-ray analysis. It is defined as having a mass of ppm or less, preferably 10% by mass or less, and more preferably not more than the detection limit. This means that even if particles are not actively added to the polyester base material, the contamination component derived from foreign matter, the raw material resin, or the dirt adhering to the line or device in the manufacturing process of the polyester base material is peeled off, and the polyester is polyester. This is because it may be mixed in the base material.

The thickness of the polyester base material is preferably 100 μm or less, more preferably 50 μm or less, still more preferably 35 μm or less, in terms of improving transferability. The lower limit of the thickness is not particularly limited, but 1 μm or more is preferable, 4 μm or more is more preferable, and 10 μm or more is further preferable, from the viewpoint of improving the strength and the workability.
The thickness of the polyester base material is measured according to the method for measuring the thickness of the polyester film described later.

<Specific layer>
The specific layer is a layer containing particles and a resin, and is formed on at least one surface of the polyester base material. Further, the surface of the specific layer opposite to the surface facing the polyester base material constitutes the second main surface.
By having the above-mentioned specific layer, the present film exhibits the effect of the present invention that both the scratch prevention property and the pattern linearity are excellent in a well-balanced manner.

The specific layer may be provided directly on the surface of the polyester base material or may be provided on the surface of the polyester base material via another layer, but is provided directly on the surface of the polyester base material in terms of better adhesion. Is preferable. That is, it is preferable that the surface of the specific layer on the first main surface side is in contact with the polyester base material.
The specific layer is not particularly limited as long as it contains particles and a resin, has a thickness of 1 to 200 nm, and has a specific maximum cross-sectional height SRt on the second main surface. The specific layer may contain additives other than particles and resin.

(particle)
The particles contained in the specific layer are not particularly limited as long as the maximum cross-sectional height SRt of the second main surface is included in the above range and the thickness of the specific layer is included in the above range.
Examples of the average particle size of the particles include 1 to 250 nm. The average particle size of the particles is preferably 150 nm or less, more preferably 130 nm or less, still more preferably 100 nm or less, in that the effect of the present invention is more excellent. Further, the lower limit value is preferably 10 nm or more, more preferably 30 nm or more, in that the effect of the present invention is more excellent.
Further, it is preferable that the average particle size of the particles contained in the specific layer is larger than the thickness of the specific layer.

As the particles contained in the specific layer, one type of particles may be used alone, or two or more types of particles may be used.
When the specific layer contains two or more kinds of particles having different particle sizes, the specific layer preferably contains at least one kind of particles having an average particle size within the above range, and two or more kinds having different particle sizes. It is more preferable that all the particles have an average particle size within the above range.

The average particle size of the particles contained in the specific layer is determined by the following method using a scanning electron microscope (SEM). That is, the second main surface of the polyester film is observed at a magnification of 20000 times using SEM. Observation is performed on 10 arbitrarily selected visual fields, and the area of each particle is measured using image software for particles that can be identified as protrusions in each visual field (particles that are visible as protrusions protruding from the base surface). Then, the diameter of a circle having the same area (diameter equivalent to the area circle) is calculated. The arithmetic mean value of the obtained area circle equivalent diameter is defined as the average particle size of the particles. At this time, even if dust and / or aggregated coarse particles of 1 μm or more are present, such dust and aggregated coarse particles are not counted when calculating the average particle size.
In the measurement of the average particle size, for the agglomerated particles, the particle size (secondary particle size) of the secondary particles in the agglomerated state shall be measured.

Examples of the particles contained in the specific layer include organic particles and inorganic particles. Among them, inorganic particles are preferable from the viewpoint of further improving film winding quality, haze, and durability (for example, thermal stability).
As the organic particles, resin particles are preferable. Examples of the resin constituting the resin particles include acrylic resin such as polymethyl methacrylate resin (PMMA), polyester resin, silicone resin, and styrene-acrylic resin. The resin particles preferably have a crosslinked structure. Examples of the resin particles having a crosslinked structure include divinylbenzene crosslinked particles.
Examples of the inorganic particles include silica particles (silicon dioxide particles, colloidal silica), titania particles (titanium oxide particles), calcium carbonate, barium sulfate, and alumina particles (aluminum oxide particles). Among the above, as the inorganic particles, silica particles are preferable from the viewpoint of further improving haze and durability.

The shape of the particles is not particularly limited, and examples thereof include rice granules, spheres, cubes, spindles, scales, aggregates, and indefinite shapes. The aggregated state means a state in which the primary particles are aggregated. The shape of the aggregated particles is not limited, but a spherical shape or an indefinite shape is preferable.
Further, the particles may be particles having a hollow structure (hollow particles) or particles having no hollow structure (solid particles), but are excellent in pattern linearity (transparency). In that respect, solid particles are preferred. As used herein, the hollow structure means a structure consisting of an inner cavity and an outer shell surrounding the cavity. Solid particles have less change in refractive index and can suppress light scattering.

As the aggregated particles having no hollow structure, fumed silica particles are preferable. Examples of commercially available products include Aerosil series manufactured by Nippon Aerosil Co., Ltd.
Colloidal silica particles are preferable as the non-aggregating particles having no hollow structure. Examples of commercially available products include the Snowtex series manufactured by Nissan Chemical Industries, Ltd.

The content of the particles in the specific layer is preferably 0.1 to 30% by mass, more preferably 1 to 25% by mass, based on the total mass of the specific layer, from the viewpoint of transportability and coatability of the release layer. 1 to 15% by mass is more preferable, and 1 to 5% by mass is particularly preferable.
The content of the particles is preferably 0.0001 to 0.01% by mass, more preferably 0.0005 to 0.005% by mass, based on the total mass of the polyester film.

Further, in the specific layer, it is preferable that the content of particles having an average particle diameter of more than 250 nm is small in that the effect of the present invention is more excellent. Examples of such particles include particles having an average particle diameter of more than 250 nm, secondary particles formed by aggregating the particles, and foreign substances such as dust inevitably mixed.

(resin)
The resin contained in the specific layer is not particularly limited, and examples thereof include acrylic resin, urethane resin, polyester and polyolefin.

The specific layer is preferably formed by applying an aqueous dispersion of resin particles. In that respect, the resin is preferably an acid-modified resin. Examples of the acid-modified resin include an acrylic resin having a structural unit derived from (meth) acrylic acid, which will be described later, and a polyolefin having a carboxyl group.
Further, the acrylic resin is preferable in that the surface free energy of the specific layer is set in a desired range and the scratch prevention property is further improved.

-acrylic resin-
As used herein, the acrylic resin means a polymer having a structural unit derived from (meth) acrylate as a main component.
In addition, in this specification, "having a structural unit derived from a certain monomer as a main component" means that the structural unit is 50 mol% or more with respect to all the structural units of the polymer.
The acrylic resin is not particularly limited as long as it has a structural unit derived from (meth) acrylate, and may be a copolymer of one kind (meth) acrylate, or two or more kinds (meth). It may be a copolymer of acrylate.

The acrylic resin preferably contains a structural unit derived from a (meth) acrylate having an alkyl group at the ester moiety (alkyl (meth) acrylate).
The alkyl group in the alkyl (meth) acrylate may further have a substituent. Examples of the substituent include an aryl group, a hydroxy group and an alkoxy group, and a phenyl group, a hydroxy group or an alkoxy group having 1 to 3 carbon atoms is preferable. The number of carbon atoms of the alkyl group (more preferably unsubstituted alkyl group) which may have a substituent in the alkyl (meth) acrylate is preferably 1 to 15, more preferably 1 to 10.
In particular, in that the surface energy can be easily adjusted to a desired range, a structural unit derived from a (meth) acrylate having an unsubstituted alkyl group having 1 to 4 carbon atoms at an ester moiety and an unsubstituted moiety having 5 to 10 carbon atoms. Acrylic resins having a structural unit derived from (meth) acrylate having the alkyl group of the above in the ester moiety are preferable.

Specific examples of the above alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, and i-. Examples thereof include butyl (meth) acrylate, t-butyl (meth) acrylate, cyclohexyl (meth) acrylate, lauryl (meth) acrylate, and 2-ethylhexyl (meth) acrylate.

The acrylic resin is a copolymer of at least one (meth) acrylate and at least one vinyl monomer other than (meth) acrylate (for example, (meth) acrylamide, (meth) acrylic acid, styrene, etc.). You may.
Among them, acrylic resin, which is a copolymer having a structural unit derived from styrene and a structural unit derived from (meth) acrylate, is preferable because it is excellent in suppressing scratches on the film.

Further, the acrylic resin preferably has an acid denaturing component. The acrylic resin preferably contains a structural unit derived from (meth) acrylic acid as an acid-modifying component. The (meth) acrylic acid may form an acid anhydride or may be neutralized with at least one selected from alkali metals, organic amines and ammonia.

In the acrylic resin, the content of the structural unit derived from (meth) acrylate is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 90% by mass or more, based on all the structural units of the acrylic resin. .. The upper limit of the content of the structural unit derived from (meth) acrylate is not particularly limited, and may be 100% by mass with respect to all the structural units of the acrylic resin.

When the acrylic resin has a structural unit derived from a monomer other than the (meth) acrylate, the content thereof is preferably 0 to 30% by mass, preferably 0.1 to 30% by mass, based on all the structural units of the acrylic resin. It is more preferably 10% by mass.
When the acrylic resin has a structural unit having an acid-modifying group, the content thereof is preferably 0.1 to 10% by mass with respect to all the structural units of the acrylic resin, and is derived from (meth) acrylic acid. It is more preferable that the constituent unit to be formed is 1 to 10% by mass. By setting the content of the structural unit having an acid-modifying group in the above range, it is possible to suppress charging and lower the acid value of the acrylic resin to adjust the surface free energy of the second main surface to a desired range.
The acid value of the acrylic resin is preferably 30 mgKOH / g or less, more preferably 20 mgKOH / g or less. The lower limit of the acid value is not particularly limited and is, for example, 0 mgKOH / g, but 2 mgKOH / g or more is preferable from the viewpoint of application as an aqueous dispersion.
Here, the acid value is the mass [mg] of potassium hydroxide required to neutralize 1 g of the sample, and the unit is described as mgKOH / g in the present specification. The acid value can be calculated, for example, from the average content of acid groups in the compound.

The method for producing the acrylic resin is not particularly limited, and the acrylic resin can be prepared by polymerizing one or more kinds of (meth) acrylates with a monomer other than any (meth) acrylate by a known method.

The specific layer may contain one kind of resin alone or may contain two or more kinds of resins. Examples of the resin to be used in combination include different types of acrylic resin, urethane resin, polyolefin and polyester. Further, the resin contained in the specific layer preferably has a crosslinked structure in that it is more excellent in durability. A resin having a crosslinked structure can be formed by cross-linking the resin with a cross-linking agent described later.
The resin content is preferably 30 to 99.8% by mass, more preferably 50 to 99.5% by mass, based on the total mass of the specific layer, from the viewpoint of adjusting the maximum cross-sectional height SRt to a desired range. ..

(Additive)
The specific layer may contain additives other than the above particles and resin.
Examples of the additive contained in the specific layer include surfactants, waxes, cross-linking agents, antioxidants, ultraviolet absorbers, colorants, strengthening agents, plasticizers, antistatic agents, flame retardants, and rust preventives. Examples thereof include defoaming agents, foaming agents, lubricants, thickeners, and antifungal agents.

-Surfactant-
The specific layer preferably has a surfactant on the second main surface in that the smoothness of the region other than the portion where the protrusions formed by the particles are present is improved. By improving the smoothness of the above-mentioned region of the second main surface and reducing the surface roughness of the second main surface due to factors other than particles, SRt can be controlled within a desired range and the effect of the present invention can be improved. Can be done.

The surfactant is not particularly limited, and examples thereof include a silicone-based surfactant, a fluorine-based surfactant, and a hydrocarbon-based surfactant, and the hydrocarbon-based surfactant is easy to adjust the surface free energy. Activators are preferred.

The silicone-based surfactant is not particularly limited as long as it is a surfactant having a silicon-containing group as a hydrophobic group, and examples thereof include polydimethylsiloxane, polyether-modified polydimethylsiloxane, and polymethylalkylsiloxane.
Commercially available products of silicone-based surfactants include, for example, BYK®-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-347, BYK-348, and , BYK-349 (all manufactured by BYK), and KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, Examples thereof include KF-643, KF-6020, X-22-4515, KF-6011, KF-6012, KF-6015, and KF-6017 (all manufactured by Shin-Etsu Chemical Co., Ltd.).

The fluorine-based surfactant is not particularly limited as long as it is a surfactant having a fluorine-containing group as a hydrophobic group, and examples thereof include perfluorooctanesulfonic acid and perfluorocarboxylic acid.
Commercially available products of fluorine-based surfactants include, for example, Megafuck (registered trademark) F-114, F-410, F-440, F-447, F-553, and F-556 (all manufactured by DIC Corporation). ), And Surfron® S-211, S-221, S-231, S-233, S-241, S-242, S-243, S-420, S-661, S-651, and Examples thereof include S-386 (manufactured by AGC Seimi Chemical Co., Ltd.).
As the fluorine-based surfactant, from the viewpoint of improving environmental suitability, a compound having a linear perfluoroalkyl group having 7 or more carbon atoms, such as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), may be used. It is preferably a surfactant derived from an alternative material.

Examples of the hydrocarbon-based surfactant include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants.
Examples of the anionic surfactant include alkyl sulfates, alkylbenzene sulfonates, alkyl phosphates, and fatty acid salts.
Examples of the nonionic surfactant include polyalkylene glycol mono or dialkyl ether, polyalkylene glycol mono or dialkyl ester, and polyalkylene glycol monoalkyl ester / monoalkyl ether.
Examples of the cationic surfactant include primary to tertiary alkylamine salts, quaternary ammonium compounds and the like.
Examples of the amphoteric surfactant include a surfactant having both an anionic moiety and a cationic moiety in the molecule.

Commercially available anionic surfactants include, for example, Rapisol® A-90, A-80, BW-30, B-90, and C-70 (all manufactured by NOF CORPORATION). NIKKOL (registered trademark) OTP-100 (above, manufactured by Nikko Chemical Industries, Ltd.), Kohakul (registered trademark) ON, L-40, and Phosphanol (registered trademark) 702 (above, manufactured by Toho Chemical Industries, Ltd.) ), Viewlight (registered trademark) A-5000, and SSS (all manufactured by Sanyo Chemical Industries, Ltd.).
Commercially available nonionic surfactants include, for example, Naroacty (registered trademark) CL-95, HN-100 (trade name: manufactured by Sanyo Kasei Kogyo Co., Ltd.), and Lisolex BW400 (trade name: higher alcohol industry). EMALEX® ET-2020 (all manufactured by Nippon Emulsion Co., Ltd.), and Surfinol® 104E, 420, 440, 465, and Dynol® 604, 607 (above, manufactured by Nisshin Kagaku Kogyo Co., Ltd.).

When used in combination with an acid-modified resin, anionic surfactants and / or nonionic surfactants are preferable and anionic surfactants are preferable because they can form a particle-containing layer having a smooth surface without inhibiting the dispersion of the resin. Surfactants are more preferred. That is, as the surfactant, an anionic hydrocarbon-based surfactant is more preferable in terms of improving the surface smoothness.

The anionic hydrocarbon-based surfactant preferably has a plurality of hydrophobic end groups in terms of further improving smoothness. The hydrophobic end group may be a part of the hydrocarbon group contained in the hydrocarbon-based surfactant. For example, a hydrocarbon-based surfactant having a hydrocarbon group having a branched chain structure at the end will have a plurality of hydrophobic end groups.
Examples of anionic hydrocarbon-based surfactants having a plurality of hydrophobic end groups include di-2-ethylhexyl sulfosuccinate (having four hydrophobic end groups) and di-2-ethyloctyl sulfosuccinate (sodium sulfosuccinate). (Has four hydrophobic end groups) and branched chain alkylbenzene sulfonate (has two hydrophobic end groups).

One type of surfactant may be used, or two or more types may be used in combination.
The content of the surfactant is preferably 0.1 to 10% by mass with respect to the total mass of the specific layer, and is 0.1 to 0.1 to 10 in that it is excellent in antistatic property at the time of forming the release layer and surface smoothness. It is more preferably 5% by mass, and even more preferably 0.5 to 2% by mass.

-wax-
The specific layer preferably further contains wax because the surface free energy can be easily adjusted.
The wax is not particularly limited and may be either a natural wax or a synthetic wax. Examples of the natural wax include carnauba wax, candelilla wax, beeswax, montan wax, paraffin wax, and petroleum wax. In addition, the slip agent described in paragraph 0087 of International Publication No. 2017/169844 can also be used.
Examples of commercially available wax products include Celozol (registered trademark) series (manufactured by Chukyo Yushi Co., Ltd.).
The wax content is preferably 0 to 10% by mass with respect to the total mass of the specific layer.

-Crosslinking agent-
The resin contained in the specific layer preferably has a crosslinked structure formed by using a crosslinking agent. The cross-linking agent is not particularly limited, and known ones can be used.
Examples of the cross-linking agent include melamine compounds, oxazoline compounds, epoxy compounds, isocyanate compounds, and carbodiimide compounds, and oxazoline compounds and carbodiimide compounds are particularly preferable.
Examples of commercially available products include Carbodilite (registered trademark) V-02-L2 (manufactured by Nisshinbo Co., Ltd.) and Epocross (registered trademark) K-2020E (manufactured by Nippon Shokubai Co., Ltd.). For details of the epoxy-based compound, the isocyanate-based compound, and the melamine-based compound, the description in paragraphs 0083 to 0083 of JP2015-163457 can be referred to. The cross-linking agent described in paragraphs 882-0084 of WO 2017/169844 can also be preferably used. As the carbodiimide compound, the description in paragraphs 0038 to 0040 of JP-A-2017-087421 can be referred to.
As for the oxazoline compound, the carbodiimide compound and the isocyanate compound, the cross-linking agent described in paragraphs 0074 to 0075 of International Publication No. 2018/034294 can also be preferably used.
The content of the cross-linking agent is preferably 0 to 50% by mass with respect to the total mass of the specific layer.

The specific layer preferably has a low content of the cationic organic compound in that it aggregates with the resin and / or the particles and the coatability at the time of forming the specific layer does not deteriorate.

(Thickness)
The thickness of the specific layer is 1 to 200 nm, and 10 to 100 nm is preferable, and 20 to 100 nm is more preferable, in terms of the superior effect of the present invention, the manufacturing suitability of the specific layer, and the reduction of haze.
The thickness of the specific layer is measured by preparing a section having a cross section perpendicular to the main surface of the polyester film and using a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The arithmetic average value of the thicknesses of the five sections of the above section is used.
If the specific layer is soft and it is difficult to stably prepare a cross-sectional section, measurement may be performed using a spectrophotometer. Specifically, a unit capable of measuring absolute reflectance is installed in a spectrophotometer to measure the absolute reflectance spectrum (specific layer surface) at an incident angle of 5 degrees. The film thickness of the specific layer can be obtained by fitting the reflectance spectrum, the refractive index of the specific layer and the polyester substrate, and the spectrum calculated using the film thickness of the specific layer as parameters.

The method for forming the specific layer will be described in detail in the "specific layer forming step" described later.

[Physical characteristics, etc.]
Next, the physical characteristics of this film will be described.

(Surface free energy of the second main surface)
The surface free energy of the second main surface of this film is preferably 60 mJ / m ² or less, more preferably 50 mJ / m ² or less, further preferably 25 to 50 mJ / m ² , and particularly preferably 30 to 50 mJ / m ² . Since the surface free energy of the second main surface is within the above range, even if the maximum cross-sectional height SRt of the second main surface is within the above range, the films do not adhere too much to each other and are excellent in scratch prevention. A polyester film can be obtained in which the surface of the film is not easily scratched without foreign matter such as dust adhering to it.
The surface free energy of the second main surface (specific layer surface) can be adjusted, for example, by selecting the types of particles, resins and additives contained in the specific layer and their contents.

The surface free energy of the second main surface of the polyester film can be measured by the method described later.

(Surface free energy of the first main surface)
From the viewpoint of preventing static electricity when winding the film, the surface free energy of the first main surface is preferably 40 to 80 mJ / m ² , and more preferably 50 to 70 mJ / m ² .
Further, it is preferable that the difference between the surface free energy of the first main surface and the surface free energy of the second main surface is wide because the film is less likely to be charged. The difference between the surface free energy of the first main surface and the surface free energy of the second main surface is preferably 1 to 35 mJ / m ² , and more preferably 10 to 30 mJ / m ² .
The surface free energy of the first main surface can be adjusted by the type of resin and additive forming the layer having the first main surface. For example, when the specific layer is provided on only one side of the polyester base material and the first main surface is the surface opposite to the specific layer side of the polyester base material, the types of polyester and additives forming the polyester base material and Depending on their content, the surface free energy of the first main surface can be adjusted. When the non-polyester resin layer is provided, the surface free energy of the first main surface can be adjusted by the type of the non-polyester resin and the additive contained in the non-polyester resin layer and the content thereof. When the specific layer is provided on both sides of the polyester base material, the surface of the first main surface is free depending on the types of resins and additives contained in the specific layer on the side forming the first main surface and their contents. You can adjust the energy.

(Maximum cross-sectional height SRt of the second main surface, surface average roughness SRa)
In this film, the maximum cross-sectional height SRt of the second main surface is 20 to 150 nm. When the maximum cross-sectional height SRt of the second main surface is within the above range, a polyester film having an excellent balance between scratch prevention and pattern linearity can be obtained.
From the above viewpoint, the maximum cross-sectional height SRt of the second main surface is preferably 20 to 100 nm, more preferably 20 to 40 nm.

Further, in this film, the surface average roughness SRa of the second main surface is preferably 0.5 to 10.0 nm, more preferably 1.0 to 8.0 nm, in that the suppression stability of transfer marks is more excellent. It is preferable, and more preferably 1.0 to 5.0 nm.

The maximum cross-sectional height SRt and surface average roughness SRa of the second main surface (specific layer surface) are adjusted by, for example, the average particle size and content of the particles contained in the specific layer, and the thickness of the specific layer. Can be done. When a specific layer is formed by in-line coating, the above adjustment can be performed more easily.

The maximum cross-sectional height SRt and the surface average roughness SRa of the second main surface of the polyester film can be measured by the method described later.

(Maximum cross-sectional height SRt of the first main surface, surface average roughness SRa)
The first main surface is preferably as smooth as possible in terms of smoothing a layer such as a photosensitive resin layer laminated during DFR production. Specifically, the maximum cross-sectional height SRt of the first main surface is preferably 1 to 60 nm, more preferably 5 to 40 nm. The surface average roughness SRa of the first main surface is preferably 0 to 10.0 nm, more preferably 0 to 5.0 nm.

For the maximum cross-sectional height SRt and surface average roughness SRa of the first main surface, the polyester base material is provided with a specific layer on only one side so that particles are not substantially contained in the polyester base material and the film is formed smoothly. It can be adjusted by a method such as selecting the type of polyester and the type of additive constituting the above. When providing a non-polyester resin layer, do not put particles in the non-polyester resin layer, select the type of non-polyester resin and additives (such as surfactant) that form the non-polyester resin layer, and select the type. It can be adjusted by forming a smooth particle-containing layer.
The maximum cross-sectional height SRt and the surface average roughness SRa of the first main surface can be measured according to the above-mentioned measuring methods of the maximum cross-sectional height SRt and the surface average roughness SRa of the second main surface.

(Particle density D on the second main surface)
In this film, the density D (unit: piece / μm ² , also referred to as “particle density D”) of the particles constituting the protrusions on the second main surface is 1 to 1 in that the effect of the present invention is more excellent. It is preferably 10 pieces / μm ² , and more preferably 1 to 5 pieces / μm ² .

The particle density D can be adjusted by, for example, the average particle size and content of the particles contained in the specific layer, and the thickness of the specific layer, similarly to the maximum cross-sectional height SRt and the surface average roughness SRa. .. When a specific layer is formed by in-line coating, the above adjustment can be performed more easily.

Further, the particle density D of the particles constituting the protrusions on the second main surface of the polyester film can be measured by the method described later.

(The product of the maximum cross-sectional height SRt of the second main surface and the particle density D)
In this film, the particle density D (unit: piece / μm ² ) of the second main surface and the maximum cross-sectional height SRt (unit: unit:) of the second main surface are described in that the effect of the present invention is more excellent. The product (D × SRt) with (nm) is preferably 1000 or less, more preferably 600 or less, and even more preferably 130 or less. The lower limit is not particularly limited, but 1 or more is preferable, 20 or more is more preferable, and 50 or more is further preferable, in that the scratch prevention property is more excellent.

(Orientation)
This film is a biaxially oriented polyester film. In the present disclosure, "biaxial orientation" means a property having molecular orientation in the biaxial direction.
The molecular orientation is measured using a microwave transmission type molecular orientation meter (for example, MOA-6004, manufactured by Oji Measuring Instruments Co., Ltd.). The angle formed in the biaxial direction is preferably 90 ° ± 5 °, more preferably 90 ° ± 3 °, and even more preferably 90 ° ± 1 °. This film preferably has molecular orientation in the longitudinal direction and the width direction.

(Expansion rate)
The expansion rate of the polyester film in the width direction at 90 ° C. is preferably −0.15 to 0.15%, preferably −0.10 to 0.10%, based on the film width at 30 ° C. Is more preferable, 0 to 0.10% is further preferable, and 0 to 0.05% is particularly preferable.
By adjusting the expansion coefficient in the width direction of the polyester film at 90 ° C. within the above range, not only the expansion of the film in the width direction in the heating process can be suppressed, but also the expansion coefficient unevenness in each place on the film surface can be reduced. As a result, it is presumed that the generation of streaky defect regions due to heating can be suppressed.

The coefficient of expansion in the width direction at 90 ° C. is measured by the following method using a thermomechanical analyzer.
(1) Prepare a sample adjusted to a length of at least 20 mm in a direction parallel to the width direction of the biaxially oriented film and 4 mm in a direction orthogonal to the width direction of the biaxially oriented film.
(2) Using a thermomechanical analyzer (for example, TMA-60, manufactured by Shimadzu Corporation), a tensile load of 0.1 g is applied to a sample having a width of 4 mm and a length (distance between chucks) of 20 mm.
(3) The value of the length of the sample at each temperature (° C.) by raising the temperature of the above sample from a temperature of 20 ° C. or higher and lower than 30 ° C. (preferably 25 ° C.) to 150 ° C. at a heating rate of 5 ° C./min. To get.
(4) From the sample length (L30) at 30 ° C. and the length (L90) at 90 ° C., the expansion coefficient in the width direction at 90 ° C. is obtained using the following formula. In the present disclosure, the coefficient of expansion in the width direction is an arithmetic mean value of the coefficient of expansion obtained using five samples. A positive expansion rate means expansion, and a negative expansion rate means contraction.
Equation: Expansion rate (%) = (L90-L30) / L30 × 100

The expansion rate in the width direction of the polyester film can be adjusted, for example, by appropriately setting the draw ratio in the manufacturing process of the biaxially oriented film, the heat treatment temperature, and the film width during cooling.

(Film density)
The density of the polyester film is preferably 1.39 to 1.41 g / cm ³ , more preferably 1.395 to 1.405 g / cm ³ , and even more preferably 1.398 to 1.400 g / cm ³ .
The density of the polyester film can be measured using an electronic hydrometer (product name "SD-200L", manufactured by Alpha Mirage Co., Ltd.).

(Thickness)
The thickness of the polyester film is preferably 100 μm or less, more preferably 50 μm or less, still more preferably 35 μm or less, in terms of improving transferability. The lower limit of the thickness is not particularly limited, but 1 μm or more is preferable, 5 μm or more is more preferable, and 10 μm or more is further preferable, from the viewpoint of excellent handleability.
The thickness of the polyester film shall be the arithmetic mean value of the thicknesses at five points measured by the continuous stylus type film thickness meter.

Further, the variation in the thickness of the polyester film is preferably 7% or less, more preferably 5% or less of the average thickness of the polyester film in that the surface smoothness of the first main surface forming the release layer is more excellent. The lower limit of the thickness variation is not particularly limited, and may be 0% or more of the average thickness of the polyester film.
The thickness variation can be measured by the method described later.

〔Production method〕
As a method for producing this film (hereinafter, also referred to as “the present production method”), for example, a specific layer formation for forming a specific layer containing particles and a resin on a polyester base material containing substantially no particles is used. Examples include methods having steps. As the specific layer forming step, a step of in-line coating the polyester base material with a particle-containing layer forming composition containing particles and a resin to form a specific layer is preferable.
Further, as the present production method, there is a method having a biaxial stretching step of biaxially stretching an unstretched polyester film having a polyester base material substantially containing no particles.

The biaxial stretching may be simultaneous biaxial stretching in which longitudinal stretching and transverse stretching are performed at the same time, or sequential biaxial stretching in which longitudinal stretching and transverse stretching are divided into two or more stages. Examples of the form of sequential biaxial stretching include longitudinal stretching → transverse stretching, longitudinal stretching → transverse stretching → longitudinal stretching, longitudinal stretching → longitudinal stretching → transverse stretching, and transverse stretching → longitudinal stretching, and longitudinal stretching → transverse stretching. Is preferable.

This manufacturing method will be specifically described.
The manufacturing method includes, for example, an extrusion molding step of extruding a molten resin containing a raw material polyester into a film to form an unstretched polyester film having a polyester base material substantially free of particles, and an unstretched polyester film. A biaxial stretching step consisting of a longitudinal stretching step of stretching in the transport direction to form a uniaxially oriented polyester film and a transverse stretching step of stretching the uniaxially oriented polyester film in the width direction to form a biaxially oriented polyester film. A heat fixing step of heating and heat-fixing a biaxially oriented polyester film, a heat mitigation step of heating a polyester film heat-fixed by a heat fixing step at a temperature lower than that of the heat fixing step to relieve heat, and heat. At least one of a cooling step of cooling the heat-relaxed polyester film by the relaxation step, an expansion step of expanding the heat-relaxed polyester film in the width direction in the cooling step, and a substantially particle-free polyester substrate. Examples thereof include a method having a specific layer forming step of in-line coating a surface with a particle-containing layer forming composition containing particles and a resin to provide a specific layer.

<Extrusion molding process>
The extrusion molding step is a step of extruding a molten resin containing polyester as a raw material into a film by an extrusion molding method to form an unstretched polyester film containing substantially no particles. The raw material polyester has the same meaning as the polyester described in the above item (polyester).

The extrusion molding method is a method of molding a raw material resin into a desired shape by extruding a melt of the raw material resin from an extrusion die using a known extruder.
The melt may be extruded in a single layer or in multiple layers.

The melt extruded from the extrusion die is cooled to form a film. For example, the melt can be formed into a film by bringing the melt into contact with a casting roll and cooling and solidifying the melt on the casting roll.

The temperature of the casting roll is preferably more than (Tg-10) ° C and not more than (Tg + 30) ° C. The above-mentioned "Tg" means the glass transition temperature of the polyester constituting the film.
Here, the temperature of the polyester film and each member in the present manufacturing method can be measured by using a non-contact thermometer (for example, a radiation thermometer).
The cooled molded body (unstretched polyester film) is stripped from the cooling member such as a casting roll by using a stripping member such as a stripping roll.

<Biaxial stretching process>
The biaxial stretching step is a longitudinal stretching step of stretching the unstretched polyester film in the transport direction (hereinafter, also referred to as “longitudinal stretching”) to form a uniaxially oriented polyester film, and a longitudinal stretching step of forming the uniaxially oriented polyester film in the width direction. It has a transverse stretching step of forming a biaxially oriented polyester film by stretching (hereinafter, also referred to as “lateral stretching”).

(Vertical stretching process)
In the longitudinal stretching step, it is preferable to preheat the unstretched polyester film before longitudinal stretching. By preheating the unstretched polyester film, the polyester film can be easily stretched vertically.
The preheating temperature of the unstretched polyester film is preferably (Tg-30) to (Tg + 40) ° C., specifically 60 to 100 ° C.
The stretched roll described below may have a function of preheating the film.

The longitudinal stretching can be performed, for example, by applying tension between two or more pairs of stretching rolls installed in the transporting direction while transporting the unstretched polyester film in the longitudinal direction.
In the longitudinal stretching step, the transport speed (peripheral speed) of the film by the pair of stretch rolls A provided on the upstream side in the transport direction and the pair of stretch rolls B provided on the downstream side in the transport direction is the film by the stretch roll A. The transfer speed of the film is not particularly limited as long as it is slower than the transfer rate of the film by the stretch roll B. The transport speed of the film by the stretch roll A is preferably 5 to 60 m / min. The transport speed of the film by the stretch roll B is preferably 40 to 160 m / min.
The draw ratio in the longitudinal stretching step is appropriately set depending on the application, and is preferably 2.0 to 5.0 times.
The stretching speed in the longitudinal stretching step is preferably 800 to 1500% / sec. Here, the "stretching speed" is a percentage obtained by dividing the length Δd in the transport direction of the polyester film stretched in 1 second in the longitudinal stretching step by the length d0 in the transport direction of the polyester film before stretching. It is a value represented by.

In the longitudinal stretching step, it is preferable to heat the unstretched polyester film. This is because longitudinal stretching becomes easier by heating.
The heating temperature in the longitudinal stretching step is preferably (Tg-20) to (Tg + 50) ° C., specifically 70 to 120 ° C.

(Transverse stretching process)
The transverse stretching step is a step of transversely stretching a uniaxially oriented polyester film.
In the transverse stretching step, it is preferable to preheat the polyester film before the transverse stretching. By preheating the polyester film, the polyester film can be easily stretched laterally.
The preheating temperature is preferably (Tg-10) to (Tg + 60) ° C, specifically 80 to 120 ° C.

The stretching ratio (transverse stretching ratio) in the width direction of the uniaxially oriented polyester film in the transverse stretching step is not particularly limited, but is preferably larger than the stretching ratio in the longitudinal stretching step, and more preferably 3.0 to 6.0 times. ..
The area magnification expressed by the product of the stretching ratio in the longitudinal stretching step and the stretching ratio in the transverse stretching step has a good molecular orientation in the film width direction, and the molecular orientation is difficult to be relaxed when subjected to heat treatment. It is preferably 12.8 to 15.5 times because it is easy to maintain the state.
The heating temperature in the transverse stretching step is preferably (Tg-10) to (Tg + 80) ° C., specifically 100 to 140 ° C.
The stretching speed in the transverse stretching step is preferably 8 to 45% / sec.

<Heat fixing process>
In this production method, it is preferable to perform a heat fixing step and a heat relaxation step as a heat treatment for the polyester film laterally stretched by the transverse stretching step.
By heating and heat-fixing the biaxially oriented polyester film obtained in the transverse stretching step, the polyester can be crystallized and the shrinkage of the polyester film can be suppressed.
The surface temperature (heat fixing temperature) of the polyester film in the heat fixing step is not particularly limited, but is preferably 190 to 240 ° C.
The heating time in the heat fixing step is preferably 5 to 50 seconds.

<Heat relaxation process>
It is preferable to perform a step of heat-relaxing the polyester film heat-fixed by the heat-fixing step by heating it at a temperature lower than that of the heat-fixing step. Residual strain of the polyester film can be alleviated by heat relaxation.

The surface temperature (heat relaxation temperature) of the polyester film in the heat relaxation step is preferably 5 ° C. or higher lower than the heat fixation temperature, and specifically, the heat relaxation temperature is preferably 100 to 235 ° C.

<Cooling process>
The production method preferably includes a cooling step of cooling the heat-relaxed polyester film.
Examples of the method for cooling the polyester film in the cooling step include a method of blowing air (preferably cold air) on the film and a method of bringing the film into contact with a temperature-adjustable member (for example, a temperature control roll).
The cooling rate of the polyester film in the cooling step is not particularly limited, but is preferably more than 2000 ° C./min and less than 4000 ° C./min in that the thickness unevenness of the release layer laminated on the biaxially oriented film is reduced.

It is preferable that the above-mentioned heat fixing step, heat relaxation step and cooling step in this manufacturing method are continuously carried out in this order. This is because the load (heat history) due to repeated heating and cooling of the polyester film can be reduced, the strain inherent in the film can be reduced, and the occurrence of streak defects can be suppressed.

<Expansion process>
In the cooling step, it is preferable to perform a step of expanding the heat-relaxed polyester film in the width direction.
The expansion ratio of the polyester film in the width direction by the expansion step, that is, the ratio of the film width at the end of the cooling step to the film width before the start of the cooling step is preferably 0 to 1.3%.

<Specific layer forming process>
As a specific layer forming step, a step of forming a specific layer by in-line coating using a particle-containing layer forming composition (hereinafter, also referred to as “composition A”) containing particles and a resin will be described. The specific layer formed on at least one surface of the polyester base material by the specific layer forming step has the same meaning as the layer described in detail in the above item <Specific layer>.
The formation of the specific layer may be carried out at any stage of the present production method, for example, a coating film is formed on the surface of one or both of unstretched or stretched polyester substrates, and dried as necessary. The method can be mentioned.

First, a method of forming a specific layer using the composition A will be described.
The composition A can be prepared by mixing the particles and resin contained in the specific layer, additives added as necessary, and a solvent.
Examples of the solvent include water, ethanol, toluene, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether and propylene glycol monoethyl ether. Of these, water is preferable from the viewpoint of environment, safety and economy.

The composition A may contain one kind of solvent alone, or may contain two or more kinds of solvents.
The content of the solvent is preferably 80 to 99% by mass, more preferably 90 to 98% by mass, based on the total mass of the composition A.
That is, in the composition A, the total content of the components (solid content) other than the solvent is preferably 0.5 to 20% by mass, more preferably 1 to 10% by mass, based on the total mass of the composition A.

The particles, resins and additives contained in the composition A, including their preferred embodiments, are as described in detail in the above item <Specific layer>. When commercially available products are used as the particles contained in the composition A, the catalog values of those commercially available products may be used as the average particle size of the particles.
For each component other than the solvent in the composition A, the content of each component with respect to the total mass of the solid content of the composition A is the same as the preferable content of each component with respect to the total mass of the specific layer described above. It is preferable to adjust the content of each component in the coating liquid.

The method of applying the composition A is not particularly limited, and a known method can be used. Examples of the coating method include a spray coating method, a slit coating method, a roll coating method, a blade coating method, a spin coating method, a bar coating method and a dip coating method.

In the specific layer forming step, an in-line coating method is applied in which a coating liquid is applied to one or both of the polyester substrates while transporting the polyester substrate. By applying the in-line coating method, the heating time of the polyester base material in the manufacturing process is shortened and the heat history is not applied, so that the streak defect region of the polyester film can be reduced.
In the in-line coating method, the polyester base material to which the composition A is applied may be an unstretched polyester base material or a uniaxially oriented polyester base material, but may be a uniaxially oriented polyester group. It is preferably a material. That is, it is preferable to perform the specific layer forming step by the in-line coating method between the longitudinal stretching step and the transverse stretching step. This is because the adhesion between the polyester base material and the specific layer can be improved by simultaneously laterally stretching the uniaxially oriented polyester base material and the specific layer.

The present manufacturing method may include a winding step of obtaining a roll-shaped biaxially oriented polyester film by winding the biaxially oriented polyester film obtained through the above steps.
Further, the present manufacturing method further includes a trimming step of continuously cutting the polyester film along the transport direction and cutting off at least one end in the width direction of the polyester film before carrying out the winding step. You may.

The transport speed of the polyester film in each step other than the longitudinal stretching step of this production method is not particularly limited, but is preferably 50 to 200 m / min in terms of productivity and quality.
Further, the tension applied to the polyester film in the transport direction after the cooling step is applied until the polyester film is taken up in the above winding step is preferably 3 to 30 N / m.

[Use]
Since this film is excellent in transparency and smoothness, it is suitably used as an optical polyester film.
Above all, this film is preferably used as a polyester film for producing a dry film resist because it has excellent scratch resistance and pattern linearity. A dry film resist produced using this film can form a resist pattern having excellent pattern linearity even when a high-definition resist pattern is formed, and thus can be suitably used for forming a resist pattern. ..
A dry film resist manufactured using this film and a method for manufacturing a dry film resist using this film will be described later.

Since this film has excellent transparency and smoothness, it is suitably used for optical applications other than dry film resist production. More specifically, protective films for various uses such as dry film resists, support films for various uses such as decorative sheets and decorative sheets, molding films such as decorative layers and resin sheets, optical display films, conductive films, etc. Suitable for use as a separator for release films for various applications such as ceramic sheet production, films for semiconductor manufacturing processes, films for polarizing plate manufacturing processes, films for magnetic tapes, and adhesive films for labels, medical use, office supplies, etc. Can be done.

[DFR]
The DFR of the present invention has the present film as a temporary support and a photosensitive resin layer provided on the first main surface of the present film, and is used as a photosensitive transfer member.
The DFR may have an intermediate layer between the present film and the photosensitive resin layer.
Here, the intermediate layer means all the layers between the temporary support and the photosensitive resin layer.

The DFR of the present invention has the present film as a temporary support. The temporary support means a support that can be peeled off.
This film is as described above.

As the photosensitive resin layer, a known photosensitive resin layer can be used, but a negative photosensitive resin layer is preferable because the laminating property at high speed is more excellent. Specifically, it is preferable to have a monomer polymerizable compound having a double bond, a polymer (preferably a polymer having an acid group), and a photopolymerization initiator.
As the photosensitive resin layer, for example, the photosensitive resin layer described in JP-A-2016-224162 may be used. Further, a photosensitive resin layer containing a binder polymer, an ethylenically unsaturated compound and a photopolymerization initiator described in International Publication No. 2018/10513 is also mentioned as a preferable form. More preferable forms include a photosensitive resin layer having an alkali-soluble acrylic resin having a cyclic structure, a polyfunctional acrylate, and an oxime-based photopolymerization initiator or a bisimidazole-type photopolymerization initiator.

The DFR preferably has a protective film on the surface of the photosensitive resin layer opposite to the temporary support side.
It is also preferable to use this film as a protective film.

[DFR manufacturing method]
The method for producing the DFR of the present invention is not particularly limited, and the DFR of the present invention can be produced by a known production method.
As a method for producing DFR, for example, a step of mixing the above-mentioned constituent components of each layer and a solvent to prepare a composition for forming each layer such as a thermoplastic resin composition, and on the first main surface of this film. After applying the above composition to form a coating layer, the steps of drying the coating layer to form each layer are performed in order according to the desired layer structure, whereby the film, the intermediate layer, and the intermediate layer are formed. Examples thereof include a method of producing a DFR having a photosensitive resin layer in this order.

The DFR of the present invention has an excellent effect that a resist pattern having excellent pattern linearity can be formed even when it is used for forming a high-definition resist pattern.
Therefore, the DFR of the present invention is preferably used for manufacturing a resist pattern and circuit wiring.

The present disclosure will be described in more detail with reference to examples below. The materials, amounts, ratios, treatment contents, and treatment procedures shown in the following examples may be appropriately changed as long as they do not deviate from the gist of the present disclosure. Therefore, the scope of the present disclosure is not limited to the specific examples shown below. Unless otherwise specified, "parts", "ppm" and "%" are based on mass.

Hereinafter, in the present embodiment, the term "film" includes both a polyester base material alone and an embodiment having a polyester base material and a particle-containing layer, and an unstretched film, a uniaxially oriented film, and the like. And all of the biaxially oriented films shall be included.
Further, in each step of this embodiment, a non-contact thermometer (AD-5616 (product name), manufactured by A & D, emissivity 0.95) is used to measure the temperature of the central portion in the width direction of the film five times. Then, the arithmetic mean value of the obtained measured values was used as the measured value of the surface temperature of the film.

[Example 1]
<Extrusion molding process>
Titanium compounds (citrate chelate titanium complex, VERTEC AC-420, manufactured by Johnson Matthey), magnesium compounds (magnesium acetate tetrahydrate), and phosphorus compounds (phosphoric acid) described in Japanese Patent No. 5575671 as polymerization catalysts. Pellets of polyethylene terephthalate were produced using (trimethyl). The contents of magnesium, phosphorus, and titanium contained in the pellets were 82 mass ppm, 73 mass ppm, and 9 mass ppm, respectively, with respect to the total mass of the pellets. The obtained pellets were dried to a water content of 50 ppm or less, charged into a hopper of a uniaxial kneading extruder having a diameter of 30 mm, and then melted and extruded at 280 ° C. The melt was passed through a filter (pore diameter 2 μm) and then extruded from the die into a cooling drum at 25 ° C. to obtain an unstretched film made of polyethylene terephthalate and containing no particles. The extruded melt was brought into close contact with the cooling drum by the electrostatic application method.
The melting point (Tm) of polyethylene terephthalate constituting the unstretched film was 258 ° C., and the glass transition temperature (Tg) was 80 ° C.

<Vertical stretching process>
The unstretched film was subjected to a longitudinal stretching step by the following method.
A uniaxially oriented film was produced by passing a preheated unstretched film between two pairs of rolls having different peripheral speeds and stretching the film in the vertical direction (conveyance direction) under the following conditions.
(Vertical stretching conditions)
Preheating temperature: 75 ° C
Stretching temperature: 90 ° C
Stretching ratio: 3.4 times Stretching speed: 1300% / sec

<Particle-containing layer forming process>
The following composition 1 (composition for forming a particle-containing layer) is applied to one side of a vertically stretched uniaxially oriented film (polyester base material) with a bar coater, and the formed coating film is coated with hot air at 100 ° C. It was dried to form a particle-containing layer (specific layer). At this time, the coating amount of the composition 1 was adjusted so that the thickness of the formed particle-containing layer was 40 nm.

(Composition 1)
Composition 1 was prepared by mixing each of the components shown below. Filtration treatment of the prepared composition 1 using a filter having a pore size of 6 μm (F20, manufactured by Mahle Filter Systems Corp.) and membrane degassing (2x6 radial flow superphobic, manufactured by Polypore Co., Ltd.). After that, the obtained composition 1 was applied to the surface of the uniaxially oriented film.
A copolymer obtained by polymerizing an acrylic resin (resin A1) (methyl methacrylate, styrene, 2-ethylhexyl acrylate, 2-hydroxyethyl methacrylate and acrylic acid (containing in a mass ratio of 59: 8: 26: 5: 2)). (Aqueous dispersion containing 27.5% by mass as a solid content): 167 parts, anionic hydrocarbon-based surfactant (surfactant W-1) (“Rapisol® A-90”, sulfosuccinic acid Di-2-ethylhexyl sodium, manufactured by Nichiyu Co., Ltd., solid content 1% by mass water diluted solution): 55.7 parts, nonionic surfactant (surfactant W-2) ("Naroacty (registered trademark) CL95" , Sanyo Kasei Kogyo Co., Ltd., polyoxyalkylene alkyl ether, solid content 100% by mass): 0.7 part, wax 1 ("Cerozol (registered trademark) 524", Chukyo Oil & Fat Co., Ltd., carnauba wax dispersion, Solid content 30% by mass): 7 parts, detergent 1 ("Carbodilite (registered trademark) V-02-L2", manufactured by Nisshinbo Chemical Co., Ltd., Carbodiimide compound, solid content 10% by mass water diluted solution): 20.9 parts -Non-aggregated particles (particles 1) ("Snowtex (registered trademark) XL", average particle diameter 50 nm, colloidal silica, manufactured by Nissan Chemical Co., Ltd., solid content 40% by mass aqueous dispersion): 2.8 parts-Water: 743 copies

<Transverse stretching process>
The film subjected to the longitudinal stretching step and the particle-containing layer forming step was stretched in the width direction using a tenter under the following conditions to prepare a biaxially oriented film.
(Transverse stretching conditions)
Preheating temperature: 100 ° C
Stretching temperature: 120 ° C
Stretching ratio: 4.2 times Stretching speed: 50% / sec

<Heat fixing process>
The biaxially oriented film subjected to the above-mentioned transverse stretching step was heated under the following conditions using a tenter to perform a heat fixing step of heat-fixing the film.
(Heat fixing conditions)
Heat fixation temperature: 227 ° C
Heat fixing time: 6 seconds

<Heat relaxation process>
Next, the heat-fixed film was heated under the following conditions to perform a heat relaxation step of relaxing the tension of the film. Further, in the heat relaxation step, the film width was reduced as compared with the end of the heat fixing step by narrowing the distance (tenter width) between the gripping members of the tenter that grips both ends of the film. The following heat relaxation rate Lr was obtained from the film width L2 at the end of the heat relaxation step with respect to the film width L1 at the start of the heat relaxation step by the formula Lr = (L1-L2) / L1 × 100.
(Heat relaxation conditions)
Heat relaxation temperature: 190 ° C
Heat relaxation rate Lr: 4%

<Cooling process and expansion process>
The heat-relaxed film was subjected to a cooling step of cooling under the following conditions. Further, in the cooling step, an expansion step was carried out in which the film width was expanded as compared with the time when the heat relaxation step was completed by widening the tenter width.
The following cooling rates are the film surface temperature measured at the time of carrying into the cooling unit 50 and the cooling unit 50, with the residence time from the time the film is carried into the cooling unit 50 of the stretching machine 100 to being carried out as the cooling time ta. It was obtained by dividing the temperature difference ΔT (° C.) from the film surface temperature measured at the time of carrying out by the cooling time ta.
Further, the following expansion ratio ΔL was obtained from the film width L3 at the end of the cooling step with respect to the film width L2 of the polyester film at the start of the cooling step by the formula ΔL = (L3-L2) / L2 × 100.
(Cooling conditions)
Cooling rate: 2500 ° C / min (expansion condition)
Expansion rate ΔL: 0.6%

<Rolling process>
With respect to the film cooled by the cooling step, the film was continuously cut along the transport direction at a position 20 cm from both ends in the width direction of the film using a trimming device, and both ends of the film were trimmed. Next, an extrusion process (knurling) was performed on a region from both ends of the film to 10 mm in the width direction, and then the film was wound up at a tension of 40 kg / m.
A biaxially oriented film was produced by the above method. The width of the obtained biaxially oriented film was 1.5 m, and the winding length was 7,000 m. Moreover, when the thickness of the polyester base material and the particle-containing layer of the obtained biaxially oriented film was measured using SEM, the thickness of the polyester base material was 16 μm, and the thickness of the particle-containing layer was 40 nm.

[Examples 2 to 16]
In the particle-containing layer forming step, the compositions 2 to 16 having the compositions shown in Table 1 described later were used instead of the composition 1 used as the particle-containing layer forming composition in Example 1, respectively. A biaxially oriented film was prepared according to the method described in Example 1 except that the coating amount of each composition was adjusted so that the thickness of the particle-containing layer became the numerical value shown in Table 2 described later.

[Comparative Examples 1 and 2]
In the particle-containing layer forming step, the compositions C1 and C2 having the compositions shown in Table 1 described later were used instead of the composition 1 used as the particle-containing layer forming composition in Example 1, respectively. A biaxially oriented film was prepared according to the method described in Example 1 except that the thickness of the particle-containing layer was adjusted to the values shown in Table 2 described later.

[Comparative Example 3]
Described in Example 1 except that when the polyethylene terephthalate pellets were prepared in the extrusion molding step according to Example 1, alumina particles having an average particle diameter of 50 nm were added in an amount of 0.5% by mass with respect to the entire resin pellets. A biaxially oriented film was prepared according to the above method.

In Table 1, particles 1 to 6 in the "particle" column, resins A1 to A3, C and D in the "resin" column, W-1 to W-3 in the "surfactant" column, and wax 1 in the "wax" column. , And the cross-linking agents 1 to 3 in the "cross-linking agent" column indicate the following components, respectively.
In Table 1, the notation "amount (%)" indicates the content (unit: mass%) of each component with respect to the total mass of the solid content of the particle-containing layer forming composition.

(particle)
Particle 1: Colloidal silica ("Snowtex XL" manufactured by Nissan Chemical Industries, Ltd., average particle diameter 50 nm)
Particle 2: Colloidal silica ("Snowtex YL" manufactured by Nissan Chemical Industries, Ltd., average particle diameter 50-80 nm)
Particle 3: Colloidal silica ("Snowtex ZL" manufactured by Nissan Chemical Industries, Ltd., average particle diameter 70-100 nm)
Particle 4: Aggregated silica (Aerosil OX50, manufactured by Nippon Aerosil Co., Ltd., average particle size 200 nm, average primary particle size 40 nm)
Particle 5: Porous silica (average particle size 1.8 μm)
The particles 1 to 5 are particles that do not have a hollow structure.

(resin)
Resin A1: Acrylic resin (methyl methacrylate, styrene, 2-ethylhexyl acrylate, 2-hydroxyethyl methacrylate and acrylic acid emulsified and polymerized at a mass ratio of 59: 8: 26: 5: 2, a copolymer and an aqueous dispersion. )
Resin A3: Acrylic resin (aqueous dispersion obtained by polymerizing methyl methacrylate, 2-hydroxyethyl methacrylate and methacrylic acid at a mass ratio of 28:48:24 to neutralize a copolymer)
Resin C: Acid-modified polyolefin ("Zyxen (registered trademark) N" manufactured by Sumitomo Seika Chemical Co., Ltd., aqueous dispersion)
Resin D: Urethane resin (aqueous dispersion of polyurethane resin synthesized by the following method)
In a four-necked flask equipped with a stirrer, Dimroth condenser, nitrogen introduction tube, silica gel drying tube, and thermometer, 43.75 parts of 4,4-dicyclohexylmethanediiscetone, 12.85 parts of dimethylolbutanoic acid, number average. 153.41 parts of polyhexamethylene carbonate diol having a molecular weight of 2000, 0.03 part of dibutyltin dilaurate, and 84.00 parts of acetone as a solvent were added, and the mixture was stirred at 75 ° C. for 3 hours under a nitrogen atmosphere, and the reaction solution became a predetermined amine. It was confirmed that the equivalent amount was reached. Next, the reaction solution was cooled to 40 ° C., and then 8.77 parts of triethylamine was added to obtain a polyurethane prepolymer solution. Next, 450 parts of water was added to a reaction vessel equipped with a homodisper capable of high-speed stirring, adjusted to 25 ° C., and the polyurethane prepolymer solution was added and dispersed in water while stirring and mixing at 2000 rpm. Then, under reduced pressure, acetone and a part of water were removed to prepare an aqueous dispersion of a polyurethane resin having a solid content of 37%.

(Surfactant)
W-1: Anionic hydrocarbon-based surfactant (“Rapisol® A-90” manufactured by NOF CORPORATION)
W-2: Nonionic surfactant ("Naroacty (registered trademark) CL95" manufactured by Sanyo Chemical Industries, Ltd., polyoxyalkylene alkyl ether, solid content 100% by mass)
W-3: Fluorosurfactant (“Surflon (registered trademark) S-211” manufactured by AGC Seimi Chemical Co., Ltd.)

(wax)
Wax 1: Carnauba wax ("Cerozol (registered trademark) 524" manufactured by Chukyo Yushi Co., Ltd.)

(Crosslinking agent)
Crosslinking agent 1: Carbodiimide crosslinking agent ("Carbodilite (registered trademark) V-02-L2" manufactured by Nisshinbo Chemical Co., Ltd.)
Cross-linking agent 2: Melamine cross-linking agent (hexamethoxymethylol melamine)
Crosslinking agent 3: Oxazoline crosslinking agent ("Epocross WS-700" manufactured by Nippon Shokubai Co., Ltd.)

[Measurement of physical properties of biaxially oriented film]
The following physical properties were measured for each of the biaxially oriented films of Examples 1 to 16 and Comparative Examples 1 to 3.

<Maximum cross-sectional height SRt, surface average roughness SRa>
The maximum cross-sectional height SRt and the surface average roughness SRa of the second main surface of the biaxially oriented film were measured by the following methods.
The surface of the manufactured biaxially oriented film on the particle-containing layer side was measured using an optical interferometer (Vertscan 3300G Lite, manufactured by Hitachi High-Tech Co., Ltd.) under the following conditions, and then the built-in data analysis software ( By analysis with VS-Measure5), the maximum cross-sectional height SRt of the second main surface of the biaxially oriented film (the notation in the optical interferometer is “St”) and the surface average roughness SRa (in the optical interferometer). The notation is "Sa").
In the measurement of the maximum cross-sectional height SRt, the maximum value of the measured value obtained by 5 measurements with different measurement positions is adopted, and in the measurement of the surface average roughness SRa, it is obtained by 5 measurements with different measurement positions. The average value of the measured values to be measured was adopted. Table 2 shows the measured maximum cross-sectional height SRt and surface average roughness SRa of the second main surface.
(Measurement condition)
-Measurement mode: WAVE mode-Objective lens: 50x-Measurement area: 186 μm x 155 μm

The maximum cross-sectional height SRt and the surface average roughness SRa of the first main surface of the biaxially oriented film were measured by the same method as above. In each of the examples, the maximum cross-sectional height SRt of the first main surface was 18 nm, and the maximum cross-sectional height SRa of the first main surface was 1 nm.

<Surface free energy>
The surface free energy of the second main surface of the biaxially oriented film was measured by the following method.
Using a contact angle meter (DROPMASTER-501 manufactured by Kyowa Interface Chemistry Co., Ltd.), droplets are dropped on the surface of the manufactured biaxially oriented film on the particle-containing layer side under the condition of 25 ° C., and the droplets are surfaced. The contact angle was measured 1 second after adhering to the surface. Using 2 μL of purified water, 1 μL of methylene iodide and 1 μL of ethylene glycol as droplets, the surface free energy was calculated by the method of Kitazaki and Hata from each measured contact angle. The measured surface free energy of the second main surface is shown in Table 2.
As a result of measuring the surface free energy of the first main surface of the biaxially oriented film by the same method as above, the surface free energy of the first main surface was 59.7 mJ / m ² in all the examples. ..

<Average particle size, particle density D>
The average particle size and the particle density D of the particles contained in the particle-containing layer were measured by the following methods.
Using a scanning electron microscope (SEM, manufactured by Hitachi High-Tech, S4700), the surface of the biaxially oriented film on the particle-containing layer side was observed at a magnification of 20000 times to obtain an observation image of 10 fields. For particles that can be identified as protrusions from the obtained image data, the area of each particle is measured using image software and converted into the diameter of a circle having the same area (diameter equivalent to the area circle). After obtaining the diameter, the arithmetic average value of the particles was calculated.
Further, the value obtained by dividing the number of particles that can be identified from the image data of each visual field by the visual field area was calculated as the particle density D (unit: individual / μm ² ).
In the above-mentioned measurement of the average particle size and the particle density D, dust and aggregated coarse particles are not counted as particles.

<Thickness variation>
A sample having a length of 10 m in the longitudinal direction was taken from the produced biaxially oriented film. The thickness of this sample was measured over 10 m along the longitudinal direction using a continuous stylus type film thickness meter (TOF-6R001, manufactured by Yamabun Co., Ltd.). This measurement was performed at 5 locations with different positions in the width direction. From the obtained measured values, a value ((maximum thickness-minimum thickness) / average thickness) obtained by dividing the difference between the maximum value and the minimum value by the arithmetic mean value of all the measured values was calculated as the thickness variation.
As a result, the thickness variation of the biaxially directed film produced in each Example and each Comparative Example was 4.5%.

〔evaluation〕
The following evaluations were performed on each of the biaxially oriented films of Examples 1 to 16 and Comparative Examples 1 to 3. The evaluation results are shown in Table 2.

<Pattern linearity (LWR)>
For forming a thermoplastic resin layer having the following formulation F on the first main surface, which is the surface opposite to the particle-containing layer, with respect to the biaxially oriented film subjected to the above cooling step in each Example and each Comparative Example. The coating liquid was applied, and the obtained coating film was dried at 80 ° C. to form a thermoplastic resin layer. Next, a coating liquid for forming a water-soluble resin layer consisting of the following formulation G was applied onto the thermoplastic resin layer, and then the obtained coating film was dried at 80 ° C. to form a water-soluble resin layer. Further, a coating liquid for forming a photosensitive resin layer consisting of the following formulation H was applied onto the water-soluble resin layer, and then the obtained coating film was dried at 80 ° C. to form a photosensitive resin layer. Finally, a PET film (manufactured by Toray Industries, Inc., Lumirror 16KS40) was pressure-bonded to the surface of the photosensitive resin layer as a protective film, and then the obtained laminate was wound up to prepare a roll-shaped photosensitive transfer member.
The photosensitive transfer member is an example of DFR and has a layer structure composed of a biaxially oriented film / a thermoplastic resin layer / a water-soluble resin layer / a photosensitive resin layer / a protective film. The thickness of the thermoplastic resin layer was 2 μm, the thickness of the water-soluble resin layer was 1 μm, and the thickness of the photosensitive resin layer was 2 μm.

<Prescription F: Coating liquid for forming a thermoplastic resin layer>
-Copolymer made by polymerizing benzyl methacrylate, methacrylic acid and acrylic acid (aqueous dispersion having a mass ratio of each monomer = 75:10:15, a molecular weight of 30,000 and a solid content concentration of 30%) 22.7 parts-3 , 6-Bis (diphenylamino) fluorane: 0.12 part ・ Oxymsulfonate type photoacid generator (synthesized according to paragraph 0227 of JP2013-047765A): 0.2 part ・ Tricyclodecanedimethanoldi Acrylate: 3.32 parts ・ UV curable urethane acrylate oligomer (“8UX-015A” manufactured by Taisei Fine Chemical Co., Ltd., 15 functional): 1.66 parts ・ Polyfunctional acrylate monomer (Aronix (registered) manufactured by Toa Synthetic Co., Ltd.) (Trademark) TO-2349 "): 0.55 parts ・ Surface active agent ("Megafuck (registered trademark) F-552 "manufactured by DIC Co., Ltd.): 0.02 parts

<Prescription G: Coating liquid for forming a water-soluble resin layer>
-Polyvinyl alcohol ("Kuraray Poval (registered trademark) 4-88LA" manufactured by Kuraray Co., Ltd.): 3.22 parts-Polyvinyl pyrrolidone ("K-30" manufactured by Nippon Catalyst Co., Ltd.): 1.49 parts-Surfactant activity Agent ("Megafuck F-444" manufactured by DIC Co., Ltd.): 0.0035 parts-Methanol (manufactured by Mitsubishi Gas Chemical Company, Inc.): 57.1 parts-Ion exchanged water: 38.12 parts

<Prescription H: Coating liquid for forming a photosensitive resin layer>
-Polymer obtained by polymerizing styrene, methacrylic acid and methyl methacrylate (aqueous dispersion having a mass ratio of each monomer = 52: 29: 19, molecular weight 60,000 and solid content concentration 30%): 25.2 parts. Leuco Crystal Violet: 0.06 parts ・ Photopolymerization initiator (2- (2-chlorophenyl) -4,5-diphenylimidazole dimer): 1.03 parts ・ 4,4'-bis (diethylamino) benzophenone: 0 .04 parts ・ N-phenylcarbamoylmethyl-N-carboxymethylaniline: 0.02 parts ・ Ethylated bisphenol A dimethacrylate (“NK Ester BPE-500” manufactured by Shin-Nakamura Chemical Industry Co., Ltd.): 5.61 parts ・Polyfunctional acrylate monomer (“Aronix M-270” manufactured by Toa Synthetic Co., Ltd.): 0.58 parts ・ Phenothiazine: 0.04 parts ・ 4-Hydroxymethyl-4-methyl-1-phenyl-3-pyrazolidone: 0. 002 parts ・ Surfactant (“Megafuck F-552” manufactured by DIC Co., Ltd.): 0.048 parts ・ Propropylene glycol monomethyl ether acetate: 19.7 parts ・ Methyl ethyl ketone: 43.8 parts

A PET substrate with a copper layer was produced by forming a copper layer having a thickness of 200 nm on a polyethylene terephthalate (PET) film having a thickness of 100 μm by a sputtering method.
The roll-shaped photosensitive transfer member produced above was unwound, and the protective film was peeled off from the photosensitive transfer member. Next, the photosensitive transfer member and the above-mentioned PET substrate with a copper layer were bonded together so that the photosensitive resin layer exposed by peeling of the protective film and the copper layer were in contact with each other to obtain a laminated body. This bonding step was performed under the conditions of a roll temperature of 100 ° C., a linear pressure of 1.0 MPa, and a linear velocity of 4.0 m / min.

The photosensitive resin layer was exposed by irradiating an ultrahigh pressure mercury lamp (exposure main wavelength: 365 nm) from the biaxially oriented film side of the obtained laminate via a photomask. The photomask used for exposure had a line-and-space pattern in which the ratio of the widths of the transmission region and the light-shielding region (duty ratio) was 1: 1 and the line width (and space width) was 6 μm. .. Further, the exposure amount to the photosensitive resin layer was adjusted so that the line width of the resist pattern formed by being exposed by the irradiation light was 6 μm.
After peeling the biaxially oriented film from the exposed laminate, the laminate was shower-developed for 30 seconds using a 1.0% sodium carbonate aqueous solution having a liquid temperature of 25 ° C. By this developing step, the unexposed photosensitive resin layer and the water-soluble resin layer and the thermoplastic resin layer laminated on the unexposed photosensitive resin layer are removed from the laminate, and the line width is increased on the surface of the copper layer. A resist pattern having a line and space pattern of 6 μm was produced.

With respect to the resist pattern formed by the above method, the pattern widths (line widths of the photosensitive resin layer) at 20 arbitrarily selected points were measured using a scanning electron microscope (SEM). The standard deviation σ was calculated from the obtained line width data, and the value obtained by multiplying the standard deviation σ by 3 was defined as LWR (Line Width Roughness) and used as an index of pattern linearity.
By definition, the smaller the LWR, the smaller the line width fluctuation, which is preferable. For a pattern with a line width of 6 μm, it is evaluated as follows according to the value of LWR. It can be said that the smaller the LWR value, the better the pattern linearity. Further, it can be said that the better the pattern linearity, the better the roughness of the line width (edge roughness).
The pattern linearity of the produced resist pattern is preferably any one of "A" to "C", more preferably "A" or "B", and even more preferably "A". ..

(Evaluation criteria for pattern linearity)
A: LWR <300 nm: Very preferable as a circuit wiring board.
B: 300 nm ≦ LWR <500 nm: Preferable as a circuit wiring board.
C: 500 nm ≤ LWR <700 nm: Can be used as a circuit wiring board.
D: 700 nm ≦ LWR: The line width fluctuation is large and leads to a circuit failure, which is not preferable.

<Scratch prevention>
From the roll-shaped biaxially oriented film produced in each Example and each Comparative Example, a sample of 1.5 m × 2 m was taken from three places, the winding end portion, the position of half the roll length, and the unwinding portion. The first main surface of the obtained biaxially oriented film was visually observed using a polarion light to inspect the occurrence of scratch defects within an inspection range of 1.5 m × 2 m. From the inspection results, the scratch prevention property of the biaxially oriented film was evaluated according to the following criteria.

(Evaluation criteria for scratch prevention)
A: No scratch defects were observed in the inspection range.
B: A slight scratch defect was observed in the inspection range, but it was within the allowable range.
C: Multiple obvious scratch defects were observed in the inspection range.

Table 2 shows the physical characteristics and evaluation results of the biaxially oriented films produced in each Example and each Comparative Example.
In the table, the "average particle size" column of the "particle-containing layer" indicates the average particle size (unit: μm) of the particles contained in the particle-containing layer. A "-" in the "average particle size" column indicates that no particles were observed by the above measuring method.
In the table, the "D x SRt" column of the "second main surface" shows the particle density D (unit: pieces / μm ² ) of the particles constituting the protrusions of the second main surface and the maximum of the second main surface. Represents the product with the cross-sectional height SRt (unit: nm).

From Table 2, it was confirmed that the biaxially oriented polyester films of Examples 1 to 16 according to the present invention were more excellent in the effect of the present invention than those of Comparative Examples 1 to 3.

Further, it was confirmed that the pattern linearity was more excellent when the maximum cross-sectional height SRt of the second main surface of the biaxially oriented film was 40 nm or less (comparison of Examples 1 to 13).

It was confirmed that when the particle-containing layer of the biaxially oriented film contains an acrylic resin, the biaxially oriented film has better scratch resistance (comparison of Examples 1, 5 and 15).

When the surface free energy of the second main surface of the biaxially oriented film was 50 mJ / m ² or less, it was confirmed that the biaxially oriented film was more excellent in scratch prevention (Examples 7 and 10 and Examples). Comparison of 13 and 15).

The product (D × SRt) of the particle density D (unit: piece / μm ² ) of the particles constituting the protrusions on the second main surface and the maximum cross-sectional height SRt (unit: nm) of the second main surface is It was confirmed that when it was 600 or less, the pattern linearity was more excellent, and when the product (D × SRt) was 130 or less, the pattern linearity was further excellent (comparison of Examples 1 to 13).

It was confirmed that the pattern linearity was more excellent when the thickness of the particle-containing layer was 100 nm or less (comparison of Examples 1 to 3 and 16).

1: Polyester film 1a: First main surface 1b: Second main surface 2: Polyester base material 3: Specific layer (particle-containing layer)

Claims

With a polyester substrate that contains virtually no particles,
A particle-containing layer containing particles and a resin, which is arranged on at least one surface of the polyester substrate, is provided.
An optical polyester film having a first main surface and a second main surface.
The second main surface is a surface of the particle-containing layer opposite to the polyester substrate side.
The maximum cross-sectional height SRt of the second main surface is 20 to 150 nm.
A polyester film having a particle-containing layer having a thickness of 1 to 200 nm.
The polyester film according to claim 1, which is a polyester film for manufacturing a dry film resist.
The polyester film according to claim 1 or 2, wherein the surface free energy of the second main surface is 50 mJ / m 2 or less.
The polyester film according to claim 3, wherein the resin contains an acrylic resin.
The polyester film according to claim 4, wherein the acrylic resin is a copolymer having a structural unit derived from styrene and a structural unit derived from (meth) acrylate.
The acrylic resin has a structural unit derived from (meth) acrylate having an unsubstituted alkyl group having 1 to 4 carbon atoms in the ester moiety and an unsubstituted alkyl group having 5 to 10 carbon atoms in the ester moiety (meth). ) The polyester film according to claim 4 or 5, which has a structural unit derived from acrylate.
The polyester film according to any one of claims 1 to 6, wherein the polyester film has a thickness of 1 to 35 μm.
The polyester film according to any one of claims 1 to 7, wherein the maximum cross-sectional height SRt of the second main surface is 20 to 40 nm.
The product (D × SRt) of the density D (unit: piece / μm 2 ) of the particles constituting the protrusions on the second main surface and the maximum cross-sectional height SRt (unit: nm) of the second main surface. The polyester film according to any one of claims 1 to 8, wherein the polyester film is 600 or less.
The polyester film according to any one of claims 1 to 9, wherein the particle-containing layer further contains a hydrocarbon-based surfactant.
The polyester film according to any one of claims 1 to 10, wherein the resin has a crosslinked structure.
The polyester film according to any one of claims 1 to 11, wherein the particle-containing layer further contains wax.
The polyester film according to any one of claims 1 to 12, wherein the maximum cross-sectional height SRt of the first main surface is 5 to 40 nm.
The surface average roughness SRa of the first main surface is 0 to 5.0 nm, and the surface average roughness SRa is 0 to 5.0 nm.
The surface average roughness SRa of the second main surface is 1.0 to 5.0 nm.
The polyester film according to any one of claims 1 to 13.
The polyester film according to any one of claims 1 to 14, wherein the surface free energy of the first main surface is 50 to 70 mJ / m 2 .
The polyester film according to any one of claims 1 to 15 and the polyester film.
A dry film resist comprising a photosensitive resin layer provided on the first main surface of the polyester film.
The dry film resist according to claim 16, wherein the photosensitive resin layer contains a polymer, a polymerizable compound, and a photopolymerization initiator.
It comprises a step of in-line coating a polyester base material containing substantially no particles with a composition for forming a particle-containing layer containing particles and a resin to form a particle-containing layer.
The average particle size of the particles dispersed in the composition for forming a particle-containing layer is 10 to 250 nm.
The method for producing a polyester film according to any one of claims 1 to 15.