JP2021059031A - Film for dry film resist substrate - Google Patents

Abstract

To provide a new film for a dry film resist substrate that, in relation to a polyester film to be used for forming a dry film resist, and in particular, a polyester film that can be used suitably as a support film, can reduce occurrence of a finer aggregate (foreign substance) that may cause curing inhibition of the resist while maintaining flatness of the film surface and winding characteristics.SOLUTION: There is provided a film for a dry film resist substrate made of a polyester film including a polyester layer (B) and a polyester layer (A) on at least one surface thereof, the polyester layer (A) containing particles having an average particle diameter ranging from 0.03 to 0.80 μm and having a maximum particle diameter of less than or equal to 1.0 μm, and the polyester film containing a titanium element and/or a germanium element.SELECTED DRAWING: None

Description

The present invention relates to a film used for forming a dry film resist (hereinafter sometimes abbreviated as "dry film resist"), particularly a film that can be suitably used as a support film constituting the dry film resist.

A dry film resist (dry film resist) is widely used as a resist for forming a wiring pattern on an electronic circuit board.
A dry film resist (dry film resist) is formed by laminating a support film (also referred to as a "carrier film") / a photoresist layer made of a photosensitive resin material / a protective film (also referred to as a "cover film"). A three-layer structure is common.

As a method of manufacturing an electronic circuit board using such a dry film resist, for example, an epoxy in which a protective film is first peeled from the dry film resist to expose a photoresist layer, and then, for example, a copper layer is laminated on the surface. After the photoresist layer is laminated on the copper layer surface of the resin substrate and the dry film resist is attached, the support film is laminated on the glass plate on which the circuit is printed to bring the dry film resist into close contact, and light is irradiated from the glass plate side. .. This light is transmitted through the transparent portion and the support film layer in the image of the circuit printed on the glass plate, and then is irradiated to the photoresist layer, and the portion of the photoresist layer irradiated with the light is cured by the light. .. Next, after removing the glass plate and the support film, the uncured portion of the photoresist layer is removed, and etching is performed using an acid or the like. At this time, the copper layer at the corresponding portion is exposed by removing the uncured portion of the photoresist layer, and the copper layer exposed by etching is removed from the epoxy resin substrate to form a circuit on the epoxy resin substrate. Then, by removing the cured photoresist layer, an electronic circuit substrate can be manufactured.

As the support film used for forming the dry film resist, a polyester film is mainly used because it is excellent in mechanical properties, optical properties, chemical resistance, heat resistance, dimensional stability, flatness and the like. There is.
Regarding this type of polyester film, for example, in Patent Document 1, a biaxially oriented laminated polyester film containing particles having an average particle diameter of 0.01 to 3.0 μm on at least one outermost surface layer of the outermost surface layer. It is disclosed that the centerline average roughness Ra is 0.005 μm or more, the maximum height Rt is less than 1.5 μm, and the haze value is set to 1.5% or less.

Patent Document 2 describes at least two polyester layers as a laminated polyester film for a dry film resist, which has excellent take-up property, can more reliably prevent the occurrence of circuit defects, and can further improve the resolution. The number of metal-containing agglomerates having a major axis of 10 μm or more is 5 pieces / 10 cm ² or less, and at least one of the outermost layers contains particles having an average particle diameter of 0.01 to 3.0 μm on the surface. A laminated polyester film for a dry film resist having a centerline average roughness Ra of 0.002 to 0.030 μm and a maximum height Rt of 0.05 to 1.0 μm is disclosed.

Japanese Unexamined Patent Publication No. 7-333853 Japanese Unexamined Patent Publication No. 2005-77646

In the dry film resist, the photoresist layer is exposed by irradiating the photoresist layer with light through the support film. Therefore, if agglomerates (foreign substances) are present in the support film, this causes inhibition of curing of the resist and causes circuit defects. Sometimes.
For example, in order to improve the handleability and winding characteristics of the support film, particles are contained in the film to form fine protrusions on the surface, but these particles aggregate to form foreign matter. Or, the metal contained in the polymerization catalyst of the resin constituting the film may agglomerate and become a foreign substance, which may cause inhibition of curing of the resist.

In recent years, the circuits formed by the miniaturization of electronic devices have become extremely complicated, the lines have become thinner, and the intervals between them have become narrower. Therefore, dry film resists are required to have higher image formation reproducibility and higher resolution. Therefore, the size of the agglomerates (foreign substances) in question is gradually becoming smaller.

Therefore, the present invention relates to a polyester film used for forming a dry film resist, particularly a polyester film that can be suitably used as a support film, and causes inhibition of curing of the resist while maintaining the flatness and winding characteristics of the film surface. It is an object of the present invention to provide a new film for a dry film resist base material capable of reducing the generation of finer agglomerates (foreign substances).

The present invention is a film for a dry film resist base material composed of a polyester film having a polyester layer (B) and a polyester layer (A) on at least one surface thereof, and the polyester layer (A) has an average particle size. Is in the range of 0.03 to 0.80 μm and contains particles having a maximum particle size of 1.0 μm or less, and the polyester film contains a titanium element and / or a germanium element. We propose a film for a film resist base material.

The film for a dry film resist base material proposed by the present invention has an advantage that the generation of agglomerates (foreign substances) such as particles and metals is reduced while maintaining the flatness, handleability and winding characteristics of the film. ..

Next, the present invention will be described based on examples of embodiments. However, the present invention is not limited to the embodiments described below.

<Dry film resist base film>
The film for a dry film resist base material of the present invention includes a polyester layer (B) and a polyester layer (A) on at least one surface thereof.
By including particles having an average particle size in the range of 0.03 to 0.80 μm and a maximum particle size of 1.0 μm or less in the polyester layer (A), the flatness, handleability and winding characteristics of the film are obtained. It is possible to reduce the generation of agglomerates (foreign substances) due to particles while maintaining the above.
In addition, the polyester film contains a titanium element and / or an antimony element. More specifically, for example, by using polyester made of a titanium compound and / or a germanium compound as a polymerization catalyst as a raw material, it is possible to reduce the generation of metal aggregates (foreign substances) contained in the polymerization catalyst. ..

<Polyester>
The polyester which is the raw material of the polyester layer (A) and the polyester layer (B) in the present invention is not particularly limited as long as it is a polyester obtained by using an aromatic dicarboxylic acid or an ester thereof and glycol as a main starting material. Good. Among them, it is preferable that 60% or more of the repeating structural units are polyester having an ethylene terephthalate unit or an ethylene-2,6-naphthalate unit.
Further, the polyester may contain a third component other than the ethylene terephthalate unit and the ethylene-2,6-naphthalate unit as a copolymerization component or a mixed component. For example, a resin compatible with a polyester resin such as polycarbonate may be mixed.

Examples of the aromatic dicarboxylic acid component include terephthalic acid, dimethyl terephthalate, 2,6-naphthalenedicarboxylic acid, isophthalic acid, phthalic acid, adipic acid, sebacic acid and the like. In particular, terephthalic acid or dimethyl terephthalate is preferable.

Examples of the glycol component include one or more of ethylene glycol, diethylene glycol, propylene glycol, butylene glycol and the like. Ethylene glycol is particularly preferred.

When the polyester is a copolymerized polyester, examples of the dicarboxylic acid component include one or more of isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, sebacic acid and the like. Examples of the glycol component include one or more of ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol and the like.

The intrinsic viscosity of the polyester used in the present invention is not particularly limited, but is preferably 0.45 to 1.0 dl / g, preferably 0.50 to 0.90 dl / g, from the viewpoint of film forming property and particle dispersibility in the polyester. g is more preferable, and 0.60 to 0.80 dl / g is further preferable.

The polyester film in the present invention contains a polyester made of a titanium compound and / or a germanium compound as a polymerization catalyst.
The titanium compound and the germanium compound have high catalytic activity and can be polymerized in a small amount. By using a polyester polymerized using the titanium compound and / or the germanium compound as a catalyst as a raw material, the amount of metal remaining in the film Is less likely to become agglomerates (foreign substances).
From the viewpoint of cost and stability, titanium compounds are preferable.
Examples of the polyester polymerization catalyst used in the present invention include antimony compounds, manganese compounds, aluminum compounds, magnesium compounds, calcium compounds and the like, in addition to titanium compounds and germanium compounds. Although the amount of metal remaining in the film increases, the antimony compound is preferable from the viewpoint of productivity, such as being able to stably adhere the film to the roll by using an electrostatic adhesion method or the like during film production. ..

The amount of polyester in the polyester layer (A) and the polyester layer (B) is preferably 70% by mass or more, more preferably 80% by mass or more, and further preferably 90% by mass or more. preferable. When the amount of polyester is at least the above lower limit value, the flexibility, strength and the like of the polyester film can be ensured.

<Polyester layer (A)>
The polyester layer (A) in the present invention is a layer containing particles having an average particle size in the range of 0.03 to 0.80 μm and a maximum particle size of 1.0 μm or less.
Further, it is provided on at least one surface of the polyester layer (B) described later, and constitutes the polyester film in the present invention.
If the polyester layer (A) does not contain the particles, not only the handleability is poor, but also a large number of scratches may be formed on the film surface in the film forming process of the polyester film. As described above, since the resist layer is exposed by irradiating the resist layer with light through the support film, if the support film of the dry film resist has foreign matter or scratches, the portion is not exposed and a circuit defect occurs. Therefore, considering that the polyester film is used as a support film for a dry film resist, it is particularly preferable that the layer A forming the surface of the base polyester film contains particles.
Further, by using the particles, the particles are less likely to cause hardening inhibition of the resist as agglomerates (foreign substances).

The average particle size of the particles contained in the polyester layer (A) is in the range of 0.03 μm to 0.80 μm.
If the average particle size of the particles is 0.80 μm or less, the transparency of the film is not impaired, while if the average particle size of the particles is 0.03 μm or more, the film surface can be appropriately roughened. Not only can the handling property be improved, but also scratches on the film surface can be suppressed in the film forming process of the polyester film.
From this point of view, the average particle size of the particles contained in the polyester layer (A) is preferably 0.03 μm to 0.80 μm, particularly within the range of 0.15 μm or more or 0.70 μm or less, and among them, 0.30 μm. It is particularly preferably in the range of the above or 0.60 μm or less.

The average particle size of the particles in the polyester layer (A) can be determined as an average value obtained by measuring the diameters of 10 or more particles with a scanning electron microscope. At that time, in the case of non-spherical particles, the average value of the longest diameter and the shortest diameter can be measured as the diameter of each particle.

Further, if the maximum particle size of the particles contained in the polyester layer (A) is 1.0 μm or less and is within this range, it is possible to suppress the particles from causing the resist to be cured as agglomerates (foreign substances).
From this point of view, the maximum particle size of the particles contained in the polyester layer (A) is preferably 0.80 μm, more preferably 0.70 μm or less, and 0. It is more preferably .60 μm or less.
The maximum particle size of the particles refers to the particle size of the primary particles constituting the particles when they are present as aggregates.

Further, the polyester layer (A) preferably contains the above-mentioned particles having an average particle size of 0.03 μm to 0.80 μm in a mass ratio (also referred to as “concentration”) of 10 to 6000 ppm.
When the content (particle concentration) of particles having an average particle size of 0.03 μm to 0.80 μm in the polyester layer (A) is 6000 ppm or less, the transparency of the film can be further improved, while the average particle size is 0. When the content (particle concentration) of particles of .03 μm to 0.80 μm is 10 ppm or more, the film surface can be appropriately roughened, and not only the handleability is improved, but also the film surface is improved in the film forming process of the polyester film. It is possible to prevent scratches from entering the film.
From this point of view, the polyester layer (A) preferably contains particles having an average particle size of 0.03 μm to 0.80 μm in a mass ratio of 10 to 6000 ppm, particularly 100 ppm or more or 5000 ppm or less, and among them 500 ppm or more or 4500 ppm or less. Among them, it is more preferably 1000 ppm or more or 4000 ppm or less.

The particles contained in the polyester layer (A) are particles having an average particle size of 0.03 to 0.80 μm, such as calcium carbonate, calcium phosphate, silica, kaolin, talc, alumina, barium sulfate, calcium fluoride, and fluoride. Examples thereof include inorganic particles such as lithium, zeolite and molybdenum sulfide, and organic particles such as ion exchange resin, crosslinked polymer and calcium oxalate, which are inorganic from the viewpoint of effectively improving the surface roughness of the film and from the viewpoint of manufacturing cost. Particles are preferable, alumina and silica are more preferable, organic particles are preferable from the viewpoint of efficiently imparting slipperiness and air bleeding property to the film surface, and crosslinked polystyrene particles and crosslinked acrylic particles are more preferable.

The particles contained in the polyester layer (A) may be one type, two or more types, or particles of the same type having different particle sizes and particle shapes may be used at the same time, and the shape of the particles is spherical. , Agglomerates, rods, flats, or other shapes, but from the viewpoint of suppressing the occurrence of scratches on the film surface in the processing process, the particles (X) and the particles having an average particle size larger than the particles (X) ( It is preferable to use Y) together.

The average particle size of the particles (X) is preferably in the range of 0.03 μm to 0.80 μm, preferably in the range of 0.03 μm to 0.20 μm, particularly in the range of 0.04 μm or more or 0.15 μm or less, and 0 in it. It is particularly preferably in the range of 0.05 μm or more or 0.10 μm or less.
If the average particle size of the particles (X) is 0.20 μm or less, it is unlikely to form agglomerates (foreign substances), and if the average particle size of the particles is 0.03 μm or more, it can contribute to improving the slipperiness of the film surface.

The mass ratio of the particles (X) in the polyester layer (A) is preferably in the range of 100 to 5000 ppm in the range of 10 to 6000 ppm, particularly in the range of 500 ppm or more or 4000 ppm or less, and among them, 1000 ppm or more or 3000 ppm or less. It is particularly preferable that it is within the range.
If the mass ratio of the particles (X) in the polyester layer (A) is 100 ppm or more, it can contribute to the improvement of the slipperiness of the film surface, and if the mass ratio of the particles (X) is 5000 ppm or less, the light transmission of the polyester film is possible. Can maintain sex.

The average particle size of the particles (Y) is preferably in the range of 0.30 μm to 0.80 μm in the range of 0.03 μm to 0.80 μm, particularly in the range of 0.35 μm or more or 0.70 μm or less, and among them, 0. It is particularly preferably in the range of .40 μm or more or 0.60 μm or less.
If the average particle size of the particles (Y) is 0.80 μm or less, it is unlikely to cause curing inhibition of the resist, and if the average particle size of the particles is 0.30 μm or more, the slipperiness of the film surface or the film is wound. The winding property is improved when it is made into a rotating body (roll body).

The mass ratio of the particles (Y) in the polyester layer (A) is preferably in the range of 10 to 3000 ppm, preferably in the range of 100 ppm or more or 2500 ppm or less, and in particular, 200 ppm or more or 2000 ppm or less. It is particularly preferable that it is within the range.
When the mass ratio of the particles (Y) in the polyester layer (A) is 10 ppm or more, the slipperiness and air bleeding property of the film surface can be imparted, and when the mass ratio of the particles (Y) is 3000 ppm or less, the polyester film. Light transmission can be maintained.

Since the average particle size of the particles (Y) is relatively larger than the average particle size of the particles (X) and the maximum particle size is 1.0 μm or less, the particles (Y) are preferably particles having a narrow particle size distribution width. Specifically, the value obtained by dividing the average particle size of the particles (Y) by the maximum particle size of the particles (Y) (average particle size of the particles (Y) / maximum particle size of the particles (Y)) is 0.4. It is preferably 0.6 or more, and particularly preferably 0.8 or more. The upper limit is usually 1.0 or less.
If the value obtained by dividing the average particle size of the particles (Y) by the maximum particle size of the particles (Y) (the average particle size of the particles (Y) / the maximum particle size of the particles (Y)) is 0.4 or more, the particles Since the maximum particle size of is not more than a certain value, it is possible to prevent the particles from causing hardening inhibition of the resist as agglomerates (foreign substances), and the particles (Y) having a relatively large average particle size are the polyester layer ( Since it is contained in A), the surface of the film can be roughened without increasing the mass ratio (concentration) of the particles in the polyester layer (A), and the handleability is improved without deteriorating the transparency of the film. Not only that, it suppresses scratches on the film surface in the film forming process of the polyester film, and is excellent in windability when the film is a wound body (roll body).

As an example of a preferable embodiment when the polyester layer (A) contains the particles (X) and the particles (Y), the average particle size of the particles (X) is in the range of 0.03 μm to 0.19 μm, and the particles (X). The average particle size of Y) is in the range of 0.20 μm to 0.80 μm, the mass ratio of the particles (X) in the polyester layer (A) is in the range of 100 to 5000 ppm, and the mass ratio of the particles (Y) is. It is in the range of 10 to 3000 ppm.
In the above aspect, the slipperiness of the film surface is excellent, the occurrence of scratches can be prevented, and the windability when the film is a wound body (roll body) is excellent.

Examples of the particles (X) and particles (Y) include inorganic particles and organic particles as described above.
As the particles (X) having a relatively small average particle size, inorganic particles are preferable from the viewpoint of effectively improving dispersibility and film surface roughness, and alumina is more preferable.
As the particles (Y) having a relatively large average particle size, organic particles are preferable from the viewpoints of difficulty in agglomeration, easy adjustment of particle size distribution, and prevention of scratches on the film surface, and among them, crosslinked polystyrene particles and crosslinked acrylic particles. Is more preferable. Inorganic particles are preferable from the viewpoint of manufacturing cost and handleability, and silica particles are more preferable.

As the polyester constituting the polyester layer (A), the polyester described above can be used, but from the viewpoint of suppressing the generation of aggregates (foreign substances) in the polyester film, a titanium compound and / or a germanium compound is used as a polymerization catalyst. It is preferable to use a polyester made of, and it is more preferable to use a polyester made of a titanium compound.
A polymerization catalyst composed of a titanium compound or a germanium compound has high catalytic activity and can be polymerized in a small amount. By using a polyester polymerized using a titanium compound and / or a germanium compound as a catalyst as a raw material, a polymer can be contained in the film. Since the amount of residual metal is reduced, there is less risk of becoming agglomerates (foreign substances).
Considering the productivity at the time of film production, specifically, the stable adhesion of the film to the roll by using the electrostatic adhesion method or the like, it is preferable to use polyester using an antimony compound as the polymerization catalyst. Considering the productivity during film production and the suppression of the generation of agglomerates (foreign substances) in the film, it is possible to use a polyester made of a titanium compound and / or a germanium compound and a polyester made of an antimony compound together as a polymerization catalyst. More preferred.
That is, from the viewpoint of suppressing the generation of agglomerates (foreign substances) in the film, the polyester layer (A) preferably contains a titanium element and / or a germanium element, and more preferably contains a titanium element. preferable.
Considering the productivity at the time of film production, the polyester layer (A) preferably contains an antimony element, and considering the productivity at the time of film production and the suppression of the generation of agglomerates (foreign substances) in the film, titanium. It is more preferable that the element and / or the germanium element and the antimony element are contained, and it is particularly preferable that the titanium element and the antimony element are contained.

The thickness of the polyester layer (A) is preferably 0.1 to 20.0 μm from the viewpoint of transparency and the like, particularly 0.3 μm or more or 10.0 μm or less, and 0.5 μm or more or 5.0 μm among them. The following is more preferable.

<Polyester layer (B)>
The polyester film in the present invention includes a polyester layer (B) and the polyester layer (A) on at least one surface thereof.
The polyester layer (B) contains substantially no particles or at least particles at a lower concentration than the polyester layer (A) in order to improve the handleability and winding characteristics of the film while maintaining the transparency of the film. Is preferably included.
The above-mentioned "substantially not contained" means that the particles are not intentionally contained, and specifically, the content of particles (particle concentration) is 200 ppm or less, more preferably 150 ppm or less.

When the polyester layer (B) contains particles, as described above, the average particle size of the particles contained in the polyester layer (B) is contained in the polyester layer (A) in order to reduce the cost and increase the transparency. It is preferably smaller than the average particle size of the particles, more preferably 0.010 μm to 0.200 μm, particularly 0.012 μm or more or 0.100 μm or less, and among them, 0.015 μm or more or 0.080 μm or less. Is particularly preferable.
Further, when the polyester layer (B) contains particles, the polyester layer (B) is also a polyester layer (A) from the viewpoint of maintaining the light transmission during exposure and eliminating circuit defects after exposure. ) Similarly, the maximum particle size of the particles is preferably 1.0 μm or less.

Further, as described above, the particle concentration in the polyester layer (B) is preferably at least lower than the particle concentration in the polyester layer (A) in order to enhance transparency, and specifically, the mass ratio is 0 to 2500 ppm. Of the above, it is more preferably 2000 ppm or less, of which 1000 ppm or less, of which 500 ppm or less is more preferable, and most preferably 100 ppm or less.

The type and shape of the particles contained in the polyester layer (B) are the same as those of the A layer.

As the polyester constituting the polyester layer (B), the polyester described above can be used, but from the viewpoint of suppressing the generation of aggregates (foreign substances) in the film, a titanium compound and / or a germanium compound is used as the polymerization catalyst. It is preferable to use polyester, and it is more preferable to use polyester made of a titanium compound.
That is, the polyester layer (B) preferably contains a titanium element and / or a germanium element, and more preferably contains a titanium element.

The thickness of the polyester layer (B) is 0.1 to 40 with respect to the thickness of the polyester layer (B) from the viewpoint of enhancing transparency and improving the handleability and winding characteristics of the film. It is preferably 9.0% or more, more preferably 1.0% or more or 20.0% or less, and further preferably 3.0% or more or 10.0% or less.

<Polyester layer (C)>
When the polyester film in the present invention includes a polyester layer (A) and a polyester layer other than the polyester layer (B) (hereinafter referred to as a polyester layer (C)), the polyester layer (C) is made from the above-mentioned polyester as a raw material. It is preferable that the particles are contained at least in a concentration lower than that of the polyester layer (A). Alternatively, it may be a layer containing particles like the polyester layer (A) and having a thickness different from that of the polyester layer (A).
The type and particle shape of the particles in the polyester layer (C) are the same as those in the polyester layer (A).

The thickness of the polyester layer (C) is preferably 1 to 300% of the thickness of the polyester layer (A) from the viewpoint of increasing transparency and reducing costs, and among them, 10 % Or more or 200% or less, more preferably 20% or more or 150% or less.

<Polyester film>
The polyester film in the present invention is a film having a polyester layer (B) and a polyester layer (A) on at least one surface thereof, and even if the polyester layer (B) is provided with polyester layers (A) on both sides. Alternatively, the polyester layer (B) may be provided with a polyester layer (A) on one side and a polyester layer (C) on the other side.
Specific configurations include a polyester layer (A) / polyester layer (B), a polyester layer (A) / polyester layer (B) / polyester layer (A), and the like. Further, polyester layer (A) / polyester layer (B) / polyester layer (C), polyester layer (A) / polyester layer (B) / polyester layer (C) / polyester layer (A) and the like can also be mentioned. .. However, it is not limited to these.

The polyester film in the present invention preferably has an intrinsic viscosity of 0.65 dl / g or more.
If the intrinsic viscosity of the polyester film in the present invention is 0.65 dl / g or more, as will be described later, even if the stretching ratio, especially the stretching ratio in the width direction (horizontal direction) is increased to 4.0 times or more, breakage will occur. Since the film can be stretched without occurring, it is possible to reduce the thickness unevenness of the film especially in the width direction, suppress the accumulation of air when the film is wound into a roll, and reduce the occurrence of wrinkles.
Further, when the intrinsic viscosity of the polyester film is 0.65 dl / g or more, the shear stress applied to each polyester layer raw material becomes large at the time of melt extrusion of each polyester layer, and the dispersibility of particles contained in the raw material is improved. Therefore, the generation of agglomerates (foreign substances) due to particles is suppressed.
From this point of view, the intrinsic viscosity of the polyester film is preferably 0.65 dl / g or more, particularly 0.65 dl / g or more or 0.90 dl / g or less, and among them 0.66 dl / g or more or 0.80 dl / g. It is more preferably g or less.
The intrinsic viscosity of the polyester film in the present invention can be adjusted by appropriately changing the polymerization conditions of the polyester as a raw material. For example, the intrinsic viscosity can be increased by increasing the molecular weight by lengthening the polymerization time or adopting solid phase polymerization.
The intrinsic viscosity means the intrinsic viscosity of all layers of the polyester film.

The polyester film in the present invention may be a non-stretched film (sheet) or a stretched film. Of these, a stretched film is preferable, and a biaxially stretched film is more preferable. When the laminated polyester film is a biaxially stretched film, it may be a sequential secondary stretched film or a simultaneous biaxially stretched film.

From the viewpoint of handleability and economy, the thickness of the polyester film in the present invention is preferably 6 μm to 63 μm, more preferably 9 μm or more or 38 μm or less, and more preferably 12 μm or more or 25 μm or less.

In the polyester film of the present invention, the number of agglomerates (foreign substances) having a major axis of 2 μm or more ^{is preferably 300 pieces / cm 2} or less, more preferably 200 pieces / cm ^{2, and} particularly preferably 100 pieces / cm ² or less.
According to the studies by the present inventors, agglomerates (foreign substances) are formed by precipitating and agglomerating the catalyst added when producing polyester and remaining in the film, or are added to the polyester layer. It is generated by agglomeration of particles, and if the particles added to the polyester layer contain particles with a large particle size (for example, the particle size exceeds 2 μm), it is counted as an agglomerate (foreign substance). It has been found that among such agglomerates (foreign substances), agglomerates (foreign substances) having a major axis of 2 μm or more cause inhibition of curing of the resist and lead to circuit defects occurring in the electronic circuit substrate to be manufactured.
For example, in the production of polyester, when antimony trioxide, which is an antimony compound, is used as a polymerization catalyst, the remaining antimony precipitates and aggregates, so that aggregates (foreign substances) containing antimony are formed in the polyester. Therefore, agglomerates (foreign substances) are present in the film using polyester, and are expanded in the film surface by being biaxially stretched. Therefore, the number of agglomerates (foreign substances) leading to circuit defects, that is, agglomerates having a major axis of 2 μm or more ^{is preferably 300 pieces / cm 2} or less, and more preferably 200 pieces / cm ² or less.

Here, the width of the circuit formed by the dry film resist is, for example, 2 to 50 μm, and the irradiation light for curing the resist is transmitted through the polyester film with a width of, for example, 2 to 50 μm. Therefore, agglomerates (foreign substances) having a major axis of less than 2 μm have a low degree of light shielding from light transmitted through the polyester film with a width of 2 to 50 μm, and circuit defects due to these agglomerates (foreign substances) occur. It was found not to. Therefore, as for the agglomerates (foreign substances) in the polyester film, those having a major axis of 2 μm or more are preferably set in the above range.

The agglomerate (foreign matter) can be obtained by measuring the maximum diameter of the agglomerate (foreign matter) using an optical microscope or the like.
Further, in the present invention, the "aggregate (foreign substance)" does not necessarily mean that some substance is aggregated. That is, if it is confirmed in the polyester film as a substance corresponding to the above major axis, it shall be applicable regardless of aggregation.

Examples of the agglomerates (foreign substances) include those in which particles are agglomerated, particles having a large particle size, metal compounds used as catalysts, and agglomerates of reduced metals, as described above.
According to the study by the present inventors, among the metal elements contained in the polyester polymerization catalyst, antimony, titanium and germanium, and among them, antimony has a higher light-shielding property than other metals, and therefore these metal elements are used. It has been found that the content of a specific content or more affects the performance of a high-definition dry film resist. Therefore, it is preferable to more reliably prevent circuit defects by adjusting the content of the antimony element and further the content of the titanium element and the germanium element.

The polyester film in the present invention preferably contains a titanium element and / or a germanium element, and more preferably contains a titanium element, from the viewpoint of suppressing the generation of aggregates (foreign substances) in the film. ..
Further, the content of the titanium element in the polyester film in the present invention is preferably 1 ppm or more and 30 ppm or less.
When the content of titanium element is 30 ppm or less, the number of titanium element-containing agglomerates (foreign substances) can be reduced in the polyester film, and the ratio of transmitted light being blocked by the titanium-containing agglomerates (foreign substances) can be reduced. It can be lowered, and it is possible to suppress a decrease in resolution and reduce circuit defects and the like that occur in the electronic circuit board.
When the content of the titanium element is 1 ppm or more, it is appropriate as the catalytic amount of the polyester, and the production efficiency of the polyester can be maintained.
The content of the titanium element in the polyester film in the present invention is preferably 1 ppm or more and 30 ppm or less, and more preferably 2 ppm or more or 25 ppm or less, and more preferably 5 ppm or more or 20 ppm or less.

The content of the germanium element in the polyester film in the present invention is also preferably 1 ppm or more and 30 ppm or less, particularly 2 ppm or more or 25 ppm or less, and 5 ppm or more or 20 ppm or less, among them, for the same reason as the above-mentioned titanium element. Is even more preferable.

The total content of the titanium element and the germanium element of the polyester film in the present invention is also preferably 1 ppm or more and 30 ppm or less for the same reason as the above-mentioned titanium element, particularly 2 ppm or more or 25 ppm or less, and among them, 5 ppm or more or It is more preferably 20 ppm or less.

It is also preferable that the polyester film in the present invention contains a titanium element and / or a germanium element and an antimony element.
As mentioned above, antimony has a higher light-shielding property than other metals, so if it contains more than a specific content, it affects the performance of high-definition dry film resists, but on the other hand, antimony elements are contained in the film. Is preferable from the viewpoint of productivity, such that the film can be stably adhered to the roll by the electrostatic adhesion method or the like at the time of film production.
As described above, from the viewpoint of the performance of the dry film resist and the productivity of the film, it is preferable that the polyester film contains a titanium element and / or a germanium element and an antimony element. Specifically, the total content of the titanium element, germanium element and antimony element is preferably 5 pppm or more and 40 ppm or less, and more preferably 10 ppm or more or 30 ppm or less.
When the polyester film does not contain a titanium element or a germanium element, the total content of the titanium element and the antimony element and the total content of the germanium element and the antimony element are also preferably in the above range.
Here, when the polyester layer (A) and the polyester layer (B) are formed of different polyesters, the contents of the titanium element, the germanium element and the antimony element in the polyester film are the titanium used as the polymerization catalyst in each polyester production. It depends on the amount of compounds, germanium compounds and antimony compounds, and the thickness of each layer.

The contents of titanium element, germanium element and antimony element in the polyester film in the present invention can be quantified by a fluorescent X-ray analysis method or the like.
When a polyester using a germanium compound as a polymerization catalyst is not used as a raw material for a polyester film, the polyester film usually does not contain a germanium element.

The polyester film in the present invention may have a structure in which a coating layer is laminated on at least one surface of the film in order to improve the handleability and winding characteristics of the film.
When the polyester film is composed of two layers, a polyester layer (A) and a polyester layer (B), it is preferable to form a coating layer on the side opposite to the polyester layer (A), that is, on the polyester layer (B) side. ..

The coating layer preferably contains particles having an average particle size of 0.005 to 0.150 μm.
When the average particle size of the particles contained in the coating layer is 0.005 μm or more, the slipperiness and curlability of the film can be suitably maintained, and when the average particle size is 0.150 μm or less, the coating layer can be used. This is preferable because the particles are less likely to fall off and the coating layer is less likely to be scraped.
From this point of view, from this point of view, the coating layer preferably contains particles having an average particle size of 0.005 to 0.150 μm, and among them, 0.010 μm or more or 0.120 μm or less, among which 0.030 μm or more or 0. It preferably contains particles of 100 μm or less.

As long as the average particle size of the particles contained in the coating layer is within the above range, the coating layer may contain particles having a particle size of less than 0.005 μm, or particles having a particle size larger than 0.150 μm. It may be included.

The average particle size of the particles in the coating layer can be determined as an average value obtained by measuring the diameters of 10 or more particles with a scanning electron microscope. At that time, in the case of non-spherical particles, the average value of the longest diameter and the shortest diameter can be measured as the diameter of each particle.

The particle concentration in the coating layer is preferably 1 to 10% by mass.
If the particle concentration in the coating layer is 1% by mass or more, slipperiness and winding improvement effect can be imparted, while if it is 10% by mass or less, the particles are less likely to aggregate and the coating layer due to particle shedding Shaving can be reduced, light transmission of the dry film resist base film is less likely to be obstructed, and circuit defects are less likely to occur.
From this point of view, the particle concentration in the coating layer is preferably 1 to 10% by mass, more preferably 2% by mass or more or 7% by mass or less, and further preferably 2% by mass or more or 5% by mass or less. .. By satisfying the specified range of the above ratio, the flatness of the polyester layer (A), the scratch prevention property, and the slipperiness of the coating layer can be simultaneously satisfied, and a more suitable film for a dry film resist base material can be obtained. Obtainable.

The ratio of the particle concentration (mass%) in the coating layer to the particle concentration (mass%) in the polyester layer (A) is preferably 1 to 10000, particularly 5 or more or 1000 or less, and 10 or more or 100 or less among them. Is preferable.

The types of particles in the coating layer and their shapes are the same as those described for the particles contained in the polyester layer (A). Of these, inorganic particles, particularly silica particles, are preferable.

The coating layer preferably further contains an antistatic agent.
When the support film laminated on the photoresist layer is peeled off, the static electricity generated by the peeling charge may attract and adhere foreign substances such as dust and dirt to the photoresist layer, resulting in irregular circuit patterns. , It is preferable to impart antistatic performance when the support film is peeled off.
By containing an antistatic agent in the coating layer, the polyester film can be combined with a high-resolution dry film resist base film having a highly flat surface in contact with the photoresist layer and having releasability and antistatic properties. can do.

Antistatic agents used for the coating layer include, for example, ionic conductive polymer compounds such as ammonium group-containing compounds, polyether compounds, sulfonic acid compounds, and betaine compounds, polyacetylene, polyphenylene, polyaniline, polypyrrole, and polyisothianaphthene. Examples thereof include π-electron-conjugated polymer compounds such as polythiophene. The polyether compound is not only an antistatic agent but also corresponds to the synthetic wax as the release agent described above.
Among these, an ionic conductive polymer compound is preferable, and an ammonium group-containing compound is particularly preferable. A coating layer formed from a coating solution containing a π-conjugated conductive polymer such as polythiophene or polyaniline is generally strongly colored. Since the film for a dry film resist base material is preferably highly transparent (low haze), a π-conjugated conductive polymer may not be suitable.
Further, since the π-conjugated conductive polymer coating material is generally more expensive than the ion conductive coating material, an ion conductive antistatic agent is preferably used from the viewpoint of manufacturing cost.

The ammonium group-containing compound is preferably a polymer compound having an ammonium group. For example, a polymer containing a monomer having an ammonium group and an unsaturated double bond as a component can be used.

As a specific example of such a polymer, for example, a polymer having a component represented by the following formula (1) as a repeating unit can be mentioned. This homopolymer or a copolymer obtained by copolymerizing a plurality of other components may be used.

In the above formula (1), R ¹ and R ² are independently hydrogen atoms, alkyl groups, phenyl groups and the like, and these alkyl groups and phenyl groups may be substituted with the groups shown below.
Substitutable groups include, for example, hydroxyl groups, amide groups, ester groups, alkoxy groups, phenoxy groups, naphthoxy groups, thioalkoxy groups, thiophenoxy groups, cycloalkyl groups, trialkylammonium alkyl groups, cyano groups, halogens and the like. .. Further, R ¹ and R ² may be chemically bonded, and for example, − (CH ₂ ) _m − (integer of m = 2 to 5), −CH (CH ₂ ) CH (CH ₃ ) −, -CH = CH-CH = CH-, -CH = CH-CH = N-, -CH = CH-N = C-, -CH ₃ OCH ₂ -,-(CH ₂ ) ₂ O (CH ₂ ) _2- And so on.

In the case of a polymer having a component represented by the above formula (1) as a repeating unit, the compatibility with other materials is improved, the transparency of the obtained coating film is improved, and the releasability is further improved. From the viewpoint of this, it is preferable that the unit is copolymerized with another repeating unit. Other repeating units include, for example, alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, n. -Acrylamide such as methylol acrylamide can be mentioned.

^{X −} in the above formula (1) can be appropriately selected as long as the gist of the present invention is not impaired. For example, halogen ions, sulfonates, phosphates, nitrates, alkyl sulfonates, carboxylates and the like can be mentioned.

Further, the polymer in which the component represented by the formula (1) and the polyethylene glycol-containing (meth) acrylate are copolymerized has a flexible structure, and a coating layer having excellent uniformity is formed during in-line coating. It is preferable because it can be obtained.

The number average molecular weight of the antistatic agent contained in the coating layer is preferably 1000 to 500,000, more preferably 2000 or more or 350,000 or less, and more preferably 5000 or more or 200,000 or less.
When the number average molecular weight of the antistatic agent is 1000 or more, the strength of the coating film can be maintained, the heat resistance stability can be maintained, and sufficient antistatic properties can be obtained. Further, when the molecular weight is 500,000 or less, it is possible to prevent the viscosity of the coating liquid from increasing, maintain good handleability and coatability, and it is suitable as a film for a dry film resist base material. It becomes.

The coating layer preferably contains wax in order to improve the slipperiness of the film. At this time, it may be contained together with the antistatic agent, or wax may be contained without the antistatic agent.
Examples of the wax that can be contained in the coating layer include natural waxes such as vegetable waxes, animal waxes, mineral waxes and petroleum waxes, and synthetic waxes such as synthetic hydrocarbons, modified waxes and hydride waxes.
Of these, polyolefin compounds are preferable. Specifically, for example, a compound having a compound such as a polymer of an unsaturated hydrocarbon such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, or a polyolefin-based compound composed of a copolymer as a basic skeleton. Used by dissolving or dispersing, both polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene copolymer, ethylene-1-butene copolymer, and propylene-1-butene. A copolymer or the like can be exemplified. More specifically, it is preferable to use a polyolefin having an acid value of 10 to 50 having an active hydrogen group at the terminal, and further using polyethylene oxide or polypropylene oxide.

When a polymer type wax is used, its number average molecular weight is preferably 2000 to 20000, and more preferably 3000 to 15000. Within these ranges, film-forming property and mold releasability can be maintained.
The softening point is preferably 70 to 170 ° C., more preferably 90 ° C. or higher or 150 ° C. or lower. Within these ranges, film-forming property and mold releasability can be maintained.

The coating layer preferably further contains a cross-linking agent in order to improve the coating film strength of the coating layer and impart abrasion resistance to the film.

Examples of the cross-linking agent include melamine compounds, oxazoline compounds, epoxy compounds, isocyanate compounds, carbodiimide compounds and the like. Among these cross-linking agents, a melamine compound is preferable from the viewpoint of good coating film strength and excellent mold release property of the coating layer. In addition, two or more of these cross-linking agents may be used in combination.

The melamine compound is a compound having a melamine skeleton in the compound, for example, an alkylolated melamine derivative, a compound obtained by reacting an alkylolated melamine derivative with an alcohol to partially or completely etherify, and these. A mixture of can be used. As the alcohol used for etherification, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, isobutanol and the like are preferably used. Further, the melamine compound may be either a monomer, a multimer of a dimer or more, or a mixture thereof. Further, a melamine in which urea or the like is co-condensed can be used, or a catalyst can be used to increase the reactivity of the melamine compound.

As the oxazoline compound, a polymer containing an oxazoline group is particularly preferable, and it can be prepared by polymerization of an addition-polymerizable oxazoline group-containing monomer alone or with another monomer. Additionally polymerizable oxazoline group-containing monomers include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-Isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline and the like can be mentioned, and one or a mixture of two or more thereof can be used.

The other monomer is not limited as long as it is a monomer copolymerizable with an addition-polymerizable oxazoline group-containing monomer, and is, for example, an alkyl (meth) acrylate (the alkyl group is a methyl group, an ethyl group, an n-propyl group, or an isopropyl group. , N-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group) and other (meth) acrylic acid esters; acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, Unsaturated carboxylic acids such as styrene sulfonic acid and its salts (sodium salt, potassium salt, ammonium salt, tertiary amine salt, etc.); unsaturated nitriles such as acrylonitrile and methacrylonitrile; (meth) acrylamide, N-alkyl (Meta) acrylamide, N, N-dialkyl (meth) acrylamide, (alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2- Unsaturated amides such as ethylhexyl group, cyclohexyl group, etc .; Vinyl esters such as vinyl acetate and vinyl propionate; Vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; α-olefins such as ethylene and propylene; Vinyl chloride, chloride Halogen-containing α, β-unsaturated monomers such as vinylidene; α, β-unsaturated aromatic monomers such as styrene and α-methylstyrene, etc. can be mentioned, and one or more of these monomers can be used. Can be used.

Examples of the epoxy compound include condensates of epichlorohydrin and ethylene glycol, polyethylene glycol, glycerin, polyglycerin, bisphenol A and other hydroxyl groups and amino groups, and examples thereof include polyepoxy compounds, diepoxy compounds and monoepoxy compounds. There are glycidylamine compounds and the like.

Examples of the polyepoxy compound include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyltris (2-hydroxyethyl) isocyanate, glycerol polyglycidyl ether, and trimethylol. Examples of the propanepolyglycidyl ether and the diepoxy compound include neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, resorcin diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, and propylene glycol diglycidyl. Ether, polypropylene glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether, monoepoxy compounds include, for example, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, glycidyl amine compounds N, N, N', Examples thereof include N'-tetraglycidyl-m-xylylene diamine, 1,3-bis (N, N-diglycidylamino) cyclohexane and the like.

The cross-linking agent is preferably used in a design for improving the performance of the coating layer by reacting it in the drying process or the film forming process. It can be inferred that unreacted products of these cross-linking agents, compounds after the reaction, or mixtures thereof are present in the completed coating layer.

The coating layer is a thermoplastic resin such as polyesters, polyurethanes, acrylic resins, polyvinyl resins, polyolefins and / or thermosetting acrylic resin, melamine as a binder in order to improve the adhesion to the polyester film. It may contain a thermosetting resin such as a resin or an epoxy resin.

The mass ratio of the particles contained in the coating layer to the antistatic agent, wax, binder, and cross-linking agent that can be further contained in the coating layer is preferably adjusted appropriately depending on the selected compound. is there.

The content (particle concentration) of the particles in the coating layer is preferably 1% by mass or more, and more preferably 2% by mass or more or 10% by mass or less.
When the content (particle concentration) of the particles in the coating layer is 1% by mass or more, it becomes easy to obtain the effect of facilitating the slipping and winding improvement of the film for the dry film resist base material, and it is 10% by mass or less. Therefore, the particles are less likely to aggregate, the scraping of the coating layer due to the falling out of the particles can be reduced, the light transmission of the film for the dry film resist base material is less likely to be hindered, and circuit defects are less likely to occur.

The content of the antistatic agent in the coating layer is preferably 5% by mass or more, and more preferably 10% by mass or more or 90% by mass or less. When the antistatic agent is a polymer of a compound having an ionic functional group, it is preferably 15 to 90% by mass, and more preferably 20% by mass or more or 90% by mass or less. When the content of the antistatic agent is in the above range, sufficient surface intrinsic resistance can be achieved, and the film for the dry film resist base material is less likely to be electrostatically adhered.

The content of the wax in the coating layer is preferably 1% by mass or more, and more preferably 2% by mass or more or 10% by mass or less. When the wax content is in the above range, it is easy to achieve a sufficient slipping effect, and it is difficult to hinder the adhesion to the polyester film.

The content of the cross-linking agent in the coating layer forming composition constituting the coating layer is preferably 1% by mass or more, and more preferably 2% by mass or more or 50% by mass or less. When the content of the cross-linking agent is 1% by mass or more, the smoothing and winding improvement effect of the film for the dry film resist base material can be easily obtained, and when it is 50% by mass or less, it is for the dry film resist base material. It is less likely to interfere with the light transmission of the film and less likely to cause circuit defects.

The content of the binder in the coating layer is preferably 1% by mass or more, and more preferably 2% by mass or more or 60% by mass or less. When the content of the binder is in the above range, sufficient adhesion to the polyester film can be obtained.

The coating layer may be used in combination with an antifoaming agent, a coating property improver, a thickener, an organic lubricant, an antistatic agent, an ultraviolet absorber, an antioxidant, a foaming agent, a dye, a pigment, etc., if necessary. It is possible.

The components of the coating layer can be analyzed, for example, by analysis of TOF-SIMS, X-ray photoelectron spectroscopy (XPS), fluorescent X-rays, and the like.

The film thickness of the coating layer is preferably 0.001 μm to 0.5 μm, and more preferably 0.005 μm or more or 0.3 μm or less, and more preferably 0.01 μm or more or 0.2 μm or less. preferable.
When the film thickness of the coating layer is 0.5 μm or less, the appearance of the coating film and the cured state of the coating film can be maintained, and when the film thickness is 0.001 μm or more, sufficient releasability can be obtained. Can be done.
Further, when the film thickness of the coating layer is 0.001 to 0.5 μm, the surface roughness of the polyester film is not affected. That is, it can be considered that the surface roughness of the polyester film and the surface roughness of the polyester film in which the coating layer is laminated are the same.

<Manufacturing method of polyester film>
The method for producing a polyester film in the present invention will be described.
For example, a raw material such as polyester resin is melted by an extruder, all layers of a die (for example, T-die, etc.) are co-melt-extruded from a base onto a rotary cooling drum and rapidly cooled to produce an unstretched laminated film. Next, the unstretched laminated film can be produced by stretching it in the vertical direction and the horizontal direction and heat-fixing it if necessary.
At this time, the stretching ratio in the horizontal direction, in other words, the width direction is preferably 4.0 times or more, and if necessary, the stretching ratio in the vertical direction is also preferably 2.5 times or more.

An example of a method for producing a polyester film composed of three layers of a polyester layer (A) / polyester layer (B) / polyester layer (A) will be described. The same applies to other laminated configurations.
First, the polyester forming the polyester layer (A) and the polyester forming the polyester layer (B) are supplied to separate extruders and heated to a temperature equal to or higher than the melting point of each polyester to be melted. Next, each polyester is extruded as a sheet from the T die so as to be laminated in the order of polyester layer (A) / polyester layer (B) / polyester layer (A). Subsequently, the sheet is rapidly cooled to below the glass transition temperature on a rotary cooling drum to obtain an amorphous unstretched film. At this time, in order to improve the flatness of the unstretched film, the adhesion between the unstretched film and the rotary cooling drum may be improved by an electrostatic application adhesion method, a liquid coating adhesion method, or the like. When the antimony element is contained, the adhesion between the unstretched film by the electrostatic application adhesion method and the rotary cooling drum is improved.

Next, a uniaxially stretched film is obtained by stretching (longitudinal stretching) the unstretched film in the longitudinal direction using a roll stretching machine. At this time, the stretching temperature is equal to or higher than the glass transition temperature of polyester, preferably 70 to 150 ° C, more preferably 75 to 130 ° C. Further, the longitudinal stretching ratio is 2.5 times or more, particularly preferably 2.8 times or more or 4.0 times or less, and more preferably 3.0 times or more or 3.5 times or less. At this time, the longitudinal stretching may be performed in only one stage, or may be performed in two or more stages.
Next, a biaxially stretched film is obtained by stretching (transversely stretching) the uniaxially stretched film in the lateral direction using a tenter stretching machine. At this time, the stretching temperature is preferably 75 to 150 ° C, more preferably 80 to 140 ° C. Further, the transverse stretching ratio is 4.0 times or more, particularly 4.2 times or more or 6.0 times or less, and among them, 4.4 times or more or 5.5 times or less is preferable, and 4.5 times or more or 4.5 times or more. It is more preferably 5.0 times or less. At this time, the lateral stretching may be performed in only one step, or may be performed in two or more steps.

Subsequently, the biaxially stretched film is heat-treated at a temperature of, for example, 150 to 250 ° C. to produce a laminated film. When the biaxially stretched film is heat-treated, the biaxially stretched film may be relaxed within 30%.
Then, if necessary, it may be wound into a roll.

The coating layer may be formed by "in-line coating" that treats the film surface during the manufacturing process of the polyester film, or by adopting "offline coating" that is applied outside the system on the polyester film once manufactured. It may be formed.

The in-line coating is a method of coating in a polyester film manufacturing process, and specifically, a method of coating at an arbitrary stage from melt extrusion of polyester to heat fixing and winding after stretching. Usually, it is coated on any of an unstretched sheet obtained by melting and quenching, a stretched uniaxially stretched film, a biaxially stretched film before heat fixing, and a film after heat fixing and before winding.

For example, in sequential biaxial stretching, a method of coating a uniaxially stretched film stretched in the longitudinal direction (longitudinal direction) and then stretching in the lateral direction is particularly excellent. According to such a method, film formation and coating layer formation can be performed at the same time, which is advantageous in terms of manufacturing cost. Further, since stretching is performed after coating, the film thickness of the coating layer can be changed by the stretching ratio, and the coating can be made thinner more easily than offline coating. Further, by providing the coating layer on the polyester film before stretching, the coating layer can be stretched together with the polyester film. As a result, the coating layer can be firmly adhered to the polyester film. Further, in the production of a biaxially stretched polyester film, the film can be restrained in the vertical and horizontal directions by stretching while gripping the end of the film with a clip or the like, and in the heat fixing step, a flat surface without wrinkles or the like. High temperature can be applied while maintaining the sex. Therefore, since the heat treatment applied after coating can be set to a high temperature which cannot be achieved by other methods, the film-forming property of the coating layer is improved, and the coating layer and the film can be more firmly adhered to each other. Furthermore, a strong coating layer can be formed, and the performance and durability of the coating layer can be improved. Therefore, as a method for forming the coating layer on at least one side of the polyester film, a production method in which the coating liquid is applied to the polyester film and then stretched in at least one direction is preferable.

As a method for forming the coating layer, for example, particles and an antistatic agent, wax, binder, cross-linking agent and the like that can be further contained in the coating layer are dispersed or dissolved in a solvent to prepare a solution for the coating layer, and the base material polyester. It can be formed by applying it to one side of a film.

The solution for the coating layer is preferably formed by coating it on one side of the polyester film as an aqueous coating liquid (water-soluble resin or water-dispersible resin using water as a medium). However, it can also be formed by applying an aqueous coating solution containing a small amount of an organic solvent.
Examples of this organic solvent include alcohols such as ethanol, isopropanol, ethylene glycol and glycerin, ethers such as ethyl cellosolve, t-butyl cellosolve, propylene glycol monomethyl ether and tetrahydrofuran, ketones such as acetone and methyl ethyl ketone, and esters such as ethyl acetate. Classes, amines such as dimethylethanolamine and the like can be exemplified. These can be used alone or in combination of two or more. By appropriately selecting and containing these organic solvents in the aqueous coating liquid as necessary, the stability, coating property or coating film characteristics of the coating liquid can be assisted.

Examples of the method for applying the solution for the coating layer to the polyester film include reverse roll coater, gravure coater, rod coater, and air doctor coater as shown in "Coating Method" by Yuji Harasaki, Maki Shoten, 1979. Alternatively, a coating device other than these can be used.

Regarding the drying and curing conditions when forming the coating layer on the polyester film in the polyester film, for example, when the coating layer is provided by offline coating, it is usually at 80 to 200 ° C. for 3 to 40 seconds, preferably 100 to 180. It is good to perform heat treatment at ° C for 3 to 40 seconds as a guide.
On the other hand, when the coating layer is provided by in-line coating, it is usually preferable to perform heat treatment at 70 to 270 ° C. for 3 to 200 seconds as a guide.

Further, regardless of the offline coating or the in-line coating, heat treatment and active energy ray irradiation such as ultraviolet irradiation may be used in combination as needed. Further, the surface of the polyester film may be subjected to surface treatment such as corona treatment or plasma treatment in advance.

Next, the features that the polyester film of the present invention can have will be described.

The average surface roughness Ra of the surface of the polyester film in the present invention is preferably in the range of 0.001 to 0.020 μm, particularly 0.002 μm or more and 0.010 μm or less, and among them, 0.003 μm or more or 0.005 μm or less. Is even more preferable.
When the surface roughness Ra of the polyester film is within the above range, the transparency of the polyester film is not impaired, and light scattering due to the unevenness of the film surface is unlikely to increase, so that the exposure amount of ultraviolet rays (UV) can be reduced. It can be suppressed so that the resolution is less likely to decrease.
When the coating layer is formed on only one side, it is preferable to form the coating layer on the side opposite to the photoresist layer forming side of the polyester film. Therefore, the average surface roughness Ra is the polyester layer (A) side of the polyester film. It is preferable that the surface is provided. The same applies to the maximum surface roughness Rt described below.

The maximum surface roughness Rt of the surface of the polyester film in the present invention is preferably in the range of 0.010 to 0.400 μm, particularly 0.015 μm or more or 0.300 μm or less, and 0.020 μm or more or 0 among them. It is more preferably .200 μm or less, and more preferably 0.025 μm or more or 0.100 μm or less.
When the maximum surface roughness Rt of the surface of the polyester film is 0.400 μm or less, it is possible to prevent uneven transfer to the photoresist layer and solve the problem of causing circuit defects when forming a fine pitch circuit. .. On the other hand, if the average surface roughness Ra is 0.001 μm or more or the maximum surface roughness Rt is 0.010 μm or more, scratches occur on the film surface for the dry film resist base material in the process appropriateness, especially in the film forming process. It can be difficult to do. Further, it is preferable because scratch transfer and exposure scattering due to the scratches to the photoresist layer are unlikely to occur and the fine pitch circuit pattern is not easily affected.

When the haze of the polyester film in the present invention is used for a high-resolution dry film resist, the exposure amount of ultraviolet rays is less likely to be insufficient, defects in a desired circuit are less likely to occur, and a decrease in resolution can be suppressed. From the viewpoint, it is preferably 1.0% or less, more preferably 0.1% or more or 0.7% or less, and more preferably 0.2% or more or 0.5% or less.

<How to use polyester film>
The polyester film in the present invention can be suitably used as a support film for a dry film resist, that is, a film for a dry film resist base material. That is, a dry film resist can be formed by laminating a photoresist layer on the polyester film of the present invention and laminating a protective film on the photoresist layer.

At this time, when the coating layer is formed on only one side of the polyester film, the coating layer is located on the surface opposite to the photoresist layer forming surface when forming the dry film resist, in other words, opposite to the coating layer. It is preferable to laminate the polyester film on the photoresist layer so that the surface of the polyester film on the side is brought into close contact with the photoresist layer.
The dry film resist usually has a laminated structure of a support film / photoresist layer / protective film. When the dry film resist is wound into a roll, the lower surface of the dry film resist, that is, the support film comes into contact with the protective film on the upper surface side. Therefore, the effect of slipperiness becomes more remarkable when the coating layer is provided on the surface in contact with the protective film. Further, since there is no coating layer on the resist surface, the adhesion between the resist and the support film is unlikely to change, and peeling defects are less likely to occur when the support film is removed from the resist.

As the photosensitive resin composition constituting the photoresist layer, a conventional composition can be used. Usually, as the photosensitive resin contained in the photosensitive resin composition for dry film resist, a negative type photosensitive resin is used, and a monomer having a polymerizable unsaturated group, a polymer, a photopolymerization initiator and the like are mainly used. Consists of a composition comprising. The photosensitive resin generally has alkali water solubility, and the exposed portion in the dry film resist processing step forms a circuit by development, and the unexposed portion is removed by a developer.

The monomer having a polymerizable unsaturated group is not particularly limited, but a monomer having one polymerizable unsaturated group, a monomer having two polymerizable unsaturated groups, and a polymerizable unsaturated group are used. Examples thereof include monomers having three or more, and these are used alone or in combination as appropriate.

Examples of the monomer having one polymerizable unsaturated group include methyl (meth) acrylate, ethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, propyl (meth) acrylate, and 2-hydroxypropyl (meth) acrylate. ) Acrylate, butyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-phenoxy-2-hydroxypropyl (meth) acrylate, 2- (meth) acryloyloxy-2-hydroxypropylphthalate, 3-chloro-2 Examples thereof include -hydroxypropyl (meth) acrylate, glycerin mono (meth) acrylate, 2- (meth) acryloyloxyethyl acid phosphate, half (meth) acrylate of a phthalic acid derivative, and N-methylol (meth) acrylamide.

Examples of the monomer having two polymerizable unsaturated groups include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, and propylene. Glycoldi (meth) acrylate, polypropylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, ethylene oxide-modified bisphenol A type di (meth) acrylate, propylene oxide-modified bisphenol A type Di (meth) acrylate, ethylene oxide / propylene oxide modified bisphenol A type di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, glycerin di (meth) acrylate, pentaerythritol di (meth) acrylate, ethylene glycol Diglycidyl ether di (meth) acrylate, diethylene glycol diglycidyl ether di (meth) acrylate, propylene glycol diglycidyl di (meth) acrylate, diglycidyl phthalate di (meth) acrylate, hydroxypivalic acid-modified neopentyl glycol di (meth) ) Acrylate and the like can be mentioned. Among these, ethylene oxide-modified bisphenol A-type di (meth) acrylate and ethylene oxide / propylene oxide-modified bisphenol A-type di (meth) acrylate are particularly preferably used.

Examples of the monomer having three or more polymerizable unsaturated groups include trimethylolpropane tri (meth) acrylate, trimethylolpropane tripropoxy (meth) acrylate, pentaerythritol tri (meth) acrylate, and dipentaerythritol penta (dipentaerythritol penta). Examples thereof include meta) acrylate, tri (meth) acryloyloxyethoxytrimethylolpropane, and glycerin polyglycidyl ether poly (meth) acrylate.

In addition to the above, an epoxy (meth) acrylate-based compound, a urethane (meth) acrylate-based compound, a polymerizable compound containing a phosphorus element, or the like may be used.

As the monomer having a polymerizable unsaturated group, a monomer having two polymerizable unsaturated groups and having a weight average molecular weight of 1500 or less, preferably 300 to 1200 is preferable, and among them, ethylene oxide-modified bisphenol A is particularly preferable. Type di (meth) acrylate and ethylene oxide / propylene oxide modified bisphenol A type di (meth) acrylate are preferably used. If the weight average molecular weight exceeds 1,500, the distance between crosslinks becomes long and sufficient curing may not be obtained, which may lead to a decrease in resolution and a decrease in fine line adhesion.

The polymer contained in the photosensitive resin composition is not particularly limited, and examples thereof include a polymer composed of an acrylic-based or methacrylic-based polymerizable monomer. It may be a homopolymer or a copolymer, or a copolymer with a polymerizable monomer other than an acrylic or methacrylic monomer. As the polymerizable monomer, carboxyl group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid, or their anhydrides, half esters, methyl (meth) acrylates, and ethyl (meth) acrylates. , Propyl (meth) acrylate, n-butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, hydroxy (Meta) acrylates such as ethyl (meth) acrylate, hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate, acrylamide, methacrylicamide, acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, vinyl acetate, alkyl vinyl ether, etc. Can be mentioned.

The weight average molecular weight of the above polymer is preferably in the range of 5,000 to 250,000, more preferably 10,000 to 200,000. If the weight average molecular weight is less than 5,000, the resin may become too soft and the resin may seep out when processed into a roll form as a photoresist film, and if it exceeds 250,000, the resolution may decrease.

The glass transition temperature (Tg) of the polymer is preferably in the range of 30 to 150 ° C. If the glass transition temperature is less than 30 ° C., the resin may become too soft and the resin may seep out when processed into a roll form as a photoresist film. If the temperature exceeds 150 ° C., the resin is used as a photoresist film. There is a possibility that the ability to follow the unevenness of the substrate surface at the time will decrease.

Conventionally known photopolymerization initiators are used as the photopolymerization initiator contained in the photosensitive resin composition. For example, benzophenone, P, P'-bis (dimethylamino) benzophenone, P, P'-bis (diethylamino) benzophenone, P, P'-bis (dibutylamino) benzophenone, 3,3'-dimethyl-4-methoxybenzophenone. Etc., benzoin derivatives such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin phenyl ether, benzoin isobutyl ether and the like, quinone derivatives such as anthraquinone and naphthoquinone, 2-chlorothioxanthone, 2 -Thioxanthone derivatives such as methylthioxanthone and 2,4-diethylthioxanthone, acetophenone derivatives such as dichloroacetophenone, 2,2-diethoxyacetophenone, 2,2-dichloro-4-phenoxyacetophenone, phenylglycilate, α-hydroxyisobutyl Propanone derivatives such as phenone, dibenzosparone, 1- (4-isopropylphenyl) -2-hydroxy-2-methyl-1-propanone, 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone. , Tribromophenylsulfone, sulfone derivatives such as tribromomethylphenylsulfone, 2,4,6- [tris (trichloromethyl)]-1,3,5-triazine, 2,4- [bis (trichloromethyl)]- 6- (4'-methoxyphenyl) -1,3,5-triazine, 2,4- [bis (trichloromethyl)] -6- (4'-methoxynaphthyl) -1,3,5-triazine, 2, 4- [bis (trichloromethyl)] -6- (piperonyl) -1,3,5-triazine, 2,4- [bis (trichloromethyl)] -6- (4'-methoxystyryl) -1,3, Triazine derivatives such as 5-triazine, aclysine and aclysine derivatives such as 9-phenylaclydin, 2,2'-bis (o-chlorophenyl) -4,5,4', 5'-tetraphenyl-1,2'-bi Imidazole, 2,2'-bis (o-chlorophenyl) -4,5,4', 5'-tetraphenyl-1,1'-biimidazole, 2,2'-bis (o-fluorophenyl) -4, 5,4', 5'-tetraphenyl-1,1'-biimidazole, 2,2'-bis (o-methoxyphenyl) -4,5,4', 5'-tetraphenyl-1,1'- Biimidazole, 2,2'-bis (p-me) Toxiphenyl) -4,5,4', 5'-tetraphenyl-1,1'-biimidazole, 2,4,2', 4'-bis [bi (p-methoxyphenyl)]-5,5' -Diphenyl-1,1'-biimidazole, 2,2'-bis (2,4-dimethoxyphenyl) -4,5,4', 5'-diphenyl-1,1'-biimidazole, 2,2' -Bis (p-methylthiophenyl) -4,5,4', 5'-diphenyl-1,1'-biimidazole, bis (2,4,5-triphenyl) -1,1'-biimidazole, etc. Hexaaryl biimidazole derivatives such as homomorphs co-linked with 1,2'-, 1,4'-, and 2,4'-disclosed in Japanese Patent Publication No. 45-373777, and others. As, benzoyl benzoic acid, methyl benzoyl benzoate, benzyl diphenyl disulfide, benzyl dimethyl ketal, 2-methyl-1- [4- (methylthio) phenyl] -2-molyfornopropan-1-one, 2,2-dimethoxy- 1,2-Diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1- [4- (2-hydroxyethoxy) -Phenyl] -2-Hydroxy-2-methyl-1-propane-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, bis (2,4,6) -Trimethylbenzoyl) -Phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis ( η5-2,4-cyclopentadiene-1-yl) -bis (2,6-difluoro-3- (1H-pyrrole-1-yl) -phenyl) titanium and the like can be mentioned. These may be used alone or in combination of two or more. Among these, 2,2-dimethoxy-1,2-diphenylethane-1-one and 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 are preferable.

In addition, the photosensitive resin composition includes amino resins such as melamine, thermal cross-linking agents such as isocyanate compounds, crystal violet, malachite green, malachite green lake, brilliant green, patent blue, methyl violet, Victoria blue, and rose aniline. , Coloring dyes such as parafuxin and ethylene violet, adhesion imparting agents, plasticizers, antioxidants, thermal polymerization inhibitors, solvents, surface tension modifiers, stabilizers, chain transfer agents, defoaming agents, flame retardants, etc. Additives can be added.

When a photosensitive resin composition is provided on a polyester film to prepare a photosensitive resin layer (photoresist layer), a method of mixing an organic solvent with the photosensitive resin composition so as to have a predetermined concentration can be mentioned. Be done. Examples of the organic solvent include acetone, methyl ethyl ketone, methanol, ethanol, isopropyl alcohol, toluene, propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, ethyl acetate, butyl acetate and the like. These may be used alone or in combination of two or more. A coating solution containing a mixture of the photosensitive resin compositions is uniformly applied to one side of the support film by a method such as a roll coater method or a bar coater method, and usually in an oven at 50 to 130 ° C. or gradually increasing in temperature. A photosensitive resin laminate (dry film resist) is produced by drying to form a photosensitive resin layer (photoresist layer), laminating a protective film on the photosensitive resin layer, and winding it into a roll. To.

The protective film constituting the dry film resist is formed of a polyolefin such as polyethylene or polypropylene, polyester or the like, and can be laminated on the opposite surface of the photoresist layer on the support film side to protect the photoresist layer.

In the dry film resist obtained by using the polyester film in the present invention as a support film, that is, a film for a dry film resist base material, the number of agglomerates (foreign substances) in the support film is reduced, and curing inhibition of the resist occurs. Since it is difficult to do so, it is possible to reduce circuit defects and the like that occur in the electronic circuit board, and it is suitable for forming a high-definition electronic circuit.

<Explanation of words and phrases>
Generally, a "sheet" is a thin product according to the definition in JIS, and its thickness is small and flat for its length and width. Generally, a "film" is thicker than its length and width. A thin, flat product that is extremely small and has an arbitrarily limited maximum thickness, and is usually supplied in the form of a roll (Japanese Industrial Standard JIS K6900). However, the boundary between the sheet and the film is not clear, and it is not necessary to distinguish between the two in the present invention. Therefore, in the present invention, even when the term "film" is used, the term "sheet" is included and the term "sheet" is used. Even if it is, it shall include "film".
Further, when the term "panel" is used, such as an image display panel or a protective panel, it includes a plate body, a sheet, and a film.

In the present specification, when "X to Y" (X, Y are arbitrary numbers) is described, it means "X or more and Y or less" and "preferably larger than X" or "preferably larger than X" unless otherwise specified. It also includes the meaning of "smaller than Y".
Further, when described as "X or more" (X is an arbitrary number), it includes the meaning of "preferably larger than X" and is described as "Y or less" (Y is an arbitrary number). In this case, unless otherwise specified, it also includes the meaning of "preferably smaller than Y".

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded.

<Polyester film forming material>
In Examples and Comparative Examples, polyester films (polyester layer (A), polyester layer (B)) were produced using the following polyesters.

<Polyester I>
A polyethylene terephthalate homopolymer using tetra-n-butyl titanate as a polymerization catalyst.
The intrinsic viscosity of polyester I was 0.70 dl / g.

<Polyester II>
Polyethylene terephthalate homopolymer using antimony trioxide as a polymerization catalyst.
The intrinsic viscosity of polyester II was 0.65 dl / g.

<Polyester III>
A polyethylene terephthalate homopolymer containing spherical alumina particles using antimony trioxide as a polymerization catalyst.
The intrinsic viscosity of polyester III is 0.61 dl / g, the average particle size of the spherical alumina particles is 0.05 μm, the maximum particle size is 0.20 μm, and the content of the spherical alumina particles is relative to the entire polyester III. It was 1.5% by mass.

<Polyester IV>
A polyethylene terephthalate homopolymer containing spherical silica particles using antimony trioxide as a polymerization catalyst.
The intrinsic viscosity of polyester IV is 0.63 dl / g, the average particle size of the spherical silica particles is 0.50 μm, the maximum particle size is 0.60 μm, and the content of the spherical silica particles is polyester IV. It was 1.0% by mass with respect to the whole.

<Polyester V>
A polyethylene terephthalate homopolymer containing antimony trioxide as a polymerization catalyst and containing ion exchange resin particles.
The intrinsic viscosity of polyester V is 0.61 dl / g, the average particle size of the ion exchange resin particles is 0.35 μm, the maximum particle size is 2.0 μm, and the content of the ion exchange resin particles is the entire polyester V. It was 0.5% by mass with respect to.

<Polyester VI>
A polyethylene terephthalate homopolymer containing silica particles using antimony trioxide as a polymerization catalyst.
The intrinsic viscosity of polyester IV is 0.63 dl / g, the average particle size of the silica particles is 3.0 μm, the maximum particle size is 4.0 μm, and the content of the spherical silica particles is the entire polyester IV. It was 0.7% by mass with respect to.

<Coating layer forming composition>
In the following Examples and Comparative Examples, the following raw materials were used and blended in the mass ratios shown in Table 2 to prepare a coating liquid as a coating layer forming composition.

・ Antistatic agent (A1)
Polydiallyl dimethylammonium chloride (average molecular weight: about 30,000)

・ Wax (B1)
An emulsification facility with an internal capacity of 1.5 L equipped with a stirrer, thermometer, and temperature controller, melting point 105 ° C, oxidation 16 mgKOH / g, density 0.93 g / mL, average molecular weight 5000, polyethylene oxide wax 300 g, ion-exchanged water 650 g and deca Add 50 g of glycerin monooleate surfactant and 10 g of 48% potassium hydroxide aqueous solution, replace with nitrogen, seal, stir at 150 ° C. for 1 hour, cool to 130 ° C., and place the high-pressure homogenizer under 400 atm. A wax emulsion that has been passed through and cooled to 40 ° C.

-Particle (C1): Silica particles having an average particle size of 0.05 μm-Particles (C2): Silica particles having an average particle size of 0.08 μm Note that the average particle size of the particles (C1) to (C3) is a transmission type electron. Obtained using a microscope (manufactured by Hitachi High-Technologies Corporation, H7650, acceleration voltage 100 kV).

・ Aqueous dispersion (D1)
Acrylic resin aqueous dispersion ethyl acrylate / n-butyl acrylate / methyl methacrylate / N-methylolacrylamide / acrylic acid = 65/21/10/2/2 (mass%) polymerized with the following composition and having a glass transition point of 40 ° C. ) Emulsified polymer (emulsifier: anionic surfactant)

-Crosslinking agent (E1): Hexamethoxymethylol melamine

<Example 1>
As the polyester layer (A), polyester I and polyester II are blended in a mass ratio of 80:20, melted by an extruder and supplied to the polyester layer (A) of the laminated die, and the polyester layer (B) is made of polyester. I was melted by an extruder and supplied to the polyester layer (B) of the laminated die. A two-kind, three-layer laminated polyester resin having a structure of A layer / B layer / A layer is co-extruded into a film, cast on a cooling drum at 35 ° C., and adhered to the surface of the cooling drum by an electrostatic adhesion method. An unstretched film that was rapidly cooled and solidified was produced.
Next, the unstretched film was preheated with a heating roll at 75 ° C., then stretched 3.2 times in the longitudinal direction between the rolls at 85 ° C. using an infrared heating heater and a heating roll in combination, and then the vertically stretched film was formed. One side is in-line coated with a coating liquid as a coating layer forming composition prepared by the formulation shown in Table 2, then the end of the film is gripped with a clip and guided into a tenter, and heated at a temperature of 95 ° C. While stretching 4.5 times in the lateral direction, heat treatment was performed at 225 ° C. for 10 seconds to obtain a thickness of 16.0 μm (A layer / B layer / A layer = 1.0 μm / 14.0 μm / 1.0 μm) and a width of 1580 mm. , A polyester film (sample) having a coating layer having a thickness of 0.030 μm on the surface was prepared.
The polyester layer (A) contains a polyester made of an antimony compound as a polymerization catalyst, that is, contains an antimony element, and it is easy to adjust the adhesion of the film to the surface of the cooling drum by the electrostatic adhesion method. Met.

<Example 2, Comparative Example 1>
A polyester film (sample) was produced in the same manner as in Example 1 except that the raw material of the polyester film was changed as shown in Table 2 without forming the coating layer.
Also in Example 2, the polyester layer (A) contains a polyester made of an antimony compound as a polymerization catalyst, that is, an antimony element is contained, and the surface of the cooling drum is subjected to the electrostatic adhesion method. It was easy to adjust the adhesion of the film.

<Comparative example 2>
A polyester film (sample) was produced in the same manner as in Example 1 except that the raw material of the polyester film was changed as shown in Table 2.

<Comparative example 3>
A polyester film (sample) was produced in the same manner as in Example 1 except that the raw material of the polyester film was changed and the thickness of the polyester layer (A) was changed as shown in Table 2 without forming the coating layer.

<Measurement method / evaluation method>
The methods for measuring and evaluating the physical property values of the materials and polyester films (samples) used in the above Examples and Comparative Examples are as follows.

(1) Thickness of polyester film The thickness of the polyester film (sample) was measured with a micrometer.

(2) Thickness of each layer of polyester film and thickness of coated layer The thickness of each layer of polyester film (polyester layer (A) and polyester layer (B)) and the thickness of coated layer are determined by a transmission electron microscope (TEM). It was measured by observation. Specifically, first, a small piece of a film sample was embedded in a resin in which a curing agent and an accelerator were mixed with an epoxy resin, and a section having a thickness of 200 nm was prepared by an ultramicrotome to prepare an observation sample. The obtained sample was observed with a transmission electron microscope (H-9000) manufactured by Hitachi High-Technologies Corporation. Of the observed cross sections, the interface between the polyester layer (A) and the polyester layer (B) and the interface between the polyester film surface and the coating layer were observed by light and dark in parallel with the polyester film. The distance between the interface and the film surface was measured for 50 transmission electron micrographs, and 10 points from the largest measurement value and 10 points from the smallest measurement value were deleted, and 30 points were averaged to obtain the measured value. did. From the average value, the thickness of each layer and the thickness of the coated layer were obtained.
However, in the transmission electron microscope, the acceleration voltage was set to 300 kV, and the magnification was set in the range of 10,000 to 100,000 times depending on the layer thickness.

(3) Content of antimony element and titanium element in polyester film (Sb amount, Ti amount)
In each Example / Comparative Example, the amount of elements in the film was determined by single sheet measurement under the conditions shown in Table 1 below using a fluorescent X-ray analyzer (manufactured by Shimadzu Corporation, model "XRF-1800"). It was. In the case of a film, the contents of the antimony element (Sb) and the titanium element (Ti) with respect to the entire film were measured by melting the film and molding it into a disk shape for measurement.

(4) Number of agglomerates (foreign substances) having a major axis of 2 μm or more in the polyester film In each Example and Comparative Example, the inside of the polyester film was observed using an optical microscope.
The obtained image was binarized with image processing software (“LUZEX” manufactured by Nireco Corporation). The agglomerates (foreign matter) in the film could be confirmed in black, and the agglomerates (foreign matter) were extracted by binarizing the obtained image.
The number of agglomerates (foreign substances) having a major axis of 2 μm or more in an area of 1.3 cm ² was counted and converted to ^{1 cm 2.}

(5) Average surface roughness of film surface (Ra)
If there is a coating layer, the average surface roughness (Ra) of the film surface on the opposite side of the coating layer, that is, the surface on the polyester layer (A) side, is measured by the surface roughness measuring instrument (SE) manufactured by Kosaka Laboratory Co., Ltd. It was obtained as follows using -3F). That is, a portion having a reference length L (2.5 mm) is extracted from the cross-sectional curve of the film obtained by the measurement in the direction of the center line, the center line of the extracted portion is defined as the x-axis, and the direction of the longitudinal magnification is defined as the y-axis. When expressed by the roughness curve y = f (x), the value given by the following equation was expressed by [μm]. The center line average roughness was expressed by obtaining 10 cross-sectional curves from the surface of the sample film and expressing the average value of the center line average roughness of the extracted portion obtained from these cross-sectional curves. The tip radius of the stylus was 2 μm, the load was 30 mg, and the cutoff value was 0.08 mm.

(6) Maximum height of film surface (Rt)
The maximum height (Rt) of the film surface similar to the average surface roughness (Ra) was measured as follows.
When the extracted part of the cross-sectional curve obtained at the time of Ra measurement is sandwiched by two straight lines parallel to the average line, the distance between these two straight lines is measured in the direction of the longitudinal magnification of the cross-sectional curve, and the value is measured. The maximum height Rt of the extracted portion was taken in units of micrometer (μm). The maximum height was obtained by obtaining 10 cross-sectional curves from the surface of the sample film and expressed by the average value of the maximum heights of the extracted portions obtained from these cross-sectional curves.

(7) Average Particle Size of Particles The average particle size of particles in each layer was determined by observing 10 or more particles with a scanning electron microscope, measuring the diameter of the particles, and calculating the average value. At that time, in the case of non-spherical particles, the average value of the longest diameter and the shortest diameter was measured as the diameter of each particle.

(8) Particle content (particle concentration) of the polyester layer (A) and the polyester layer (B)
In the polyester film (sample), the sample is scraped from the layer for which the particle concentration is to be measured, a solvent that dissolves the polyester and does not dissolve the particles is selected for dissolution treatment, and then the particles are centrifuged from the solution and the ratio to the total mass of the particles. (Ppm) was measured as the particle concentration.

(9) Intrinsic Viscosity Approximately 0.25 g of freeze-ground polyester film is added to approximately 25 mL of a mixed solvent of phenol / 1,1,2,2-tetrachloroethane (mass ratio 1/1) to a concentration of 1.00 g / dL. After dissolving at 120 ° C. for 30 minutes, cool to 30 ° C. and measure the number of seconds that only the sample solution and solvent fall with a fully automatic solution viscometer (manufactured by Centec, “DT553”) at 30 ° C. Then, the intrinsic viscosity was calculated by the following formula (2).
Intrinsic viscosity = ((1 + 4K _H η _SP ) ^0.5 -1) / (2K _HC ) ... Equation (2)
Here, η _sp = η / η _0-1 , η is the number of seconds for the sample solution to fall, η ₀ is the number of seconds for the solvent to fall, C is the concentration of the sample solution (g / dL), and K _H is for Huggins. It is a constant. K _H adopted 0.33.

(10) Film Haze According to JIS K 7105: 1981, the haze of a polyester film (sample) was measured with an integrating sphere type turbidity meter NDH-20D manufactured by Nippon Denshoku Kogyo Co., Ltd.

(11) Rewindability A polyester film (sample) was used to form a roll having a width of 1000 mm and a length of 6000 m, and the roll was wound at a speed of 100 m / min using a winder. The appearance of the roll after winding was visually inspected and evaluated according to the following criteria.
○ (good): The polyester film (sample) had no wrinkles and the roll end faces were neatly aligned.
Δ (usual): The end faces of the rolls were aligned, but the polyester film (sample) had small wrinkles.
× (poor): The polyester film (sample) meandered or the polyester film (sample) had large wrinkles during the winding of the roll.

From the results of the above Examples and Comparative Examples and the test results conducted by the present inventor so far, the polyester film contains a titanium element and / or a germanium element, and the polyester layer (A) has an average particle size. By containing particles in the range of 0.03 to 0.80 μm and a maximum particle size of 1.0 μm or less, agglomerates (foreign substances) are generated while maintaining the flatness and winding property of the film. It was found that can be reduced.

Claims (10)

A film for a dry film resist base material, which comprises a polyester film having a polyester layer (B) and a polyester layer (A) on at least one surface thereof.
The polyester layer (A) contains particles having an average particle size in the range of 0.03 to 0.80 μm and a maximum particle size of 1.0 μm or less.
A film for a dry film resist base material, wherein the polyester film contains a titanium element and / or a germanium element. The film for a dry film resist base material according to claim 1, wherein the total content of the titanium element and the germanium element in the polyester film is 1 ppm or more and 30 ppm or less. The film for a dry film resist base material according to claim 1 or 2, wherein the polyester film contains a titanium element and / or a germanium element and an antimony element. The film for a dry film resist base material according to claim 3, wherein the total content of the titanium element, the germanium element and the antimony element is 5 ppm or more and 40 ppm or less. The film for a dry film resist base material according to any one of claims 1 to 4, wherein the particle content in the polyester layer (A) is in the range of 10 to 6000 ppm. The film for a dry film resist base material according to any one of claims 1 to 5, wherein the polyester layer (A) contains two types of particles having different average particle sizes. Any of claims 1 to 6, wherein the polyester layer (A) contains particles (Y) having an average particle size in the range of 0.30 to 0.80 μm and a maximum particle size of 1.0 μm or less. The film for a dry film resist substrate according to the above. Claim that the value obtained by dividing the average particle size of the particles (Y) by the maximum particle size of the particles (Y) (the average particle size of the particles (Y) / the maximum particle size of the particles (Y)) is 0.4 or more. 7. The dry film resist substrate film according to 7. The film for a dry film resist base material according to any one of claims 1 to 8, wherein the polyester film has an intrinsic viscosity of 0.65 dl / g. The film for a dry film resist base material according to any one of claims 1 to 9, wherein a coating layer is provided on at least one surface of the polyester film.