TWI846691B - Polyester film for dry film anticorrosive agent, method for producing the same, and photosensitive laminate - Google Patents

Abstract

A polyester film for a dry film anticorrosive agent is provided as a new polyester film for DFR. The polyester film for a dry film anticorrosive agent has high flatness and transparency, good film slippage, little thickness unevenness in the width direction of the film, can be rolled up, and air can be prevented from being enclosed between the films. The polyester film for a dry film anticorrosive agent has a surface layer containing particles on at least one side of a base polyester film having an intrinsic viscosity of 0.65 dl/g or more. The polyester film for a dry film anticorrosive agent has a surface layer containing particles on at least one side of a base polyester film having an intrinsic viscosity of 0.65 dl/g or more. The characteristic is that the base polyester film is a single layer composed of a polyester layer (referred to as "A layer") or a multi-layer film having the A layer on the surface, the polyester layer contains particles with an average particle size of 0.030μm to 0.200μm at a mass ratio of 10ppm to 7000ppm, and substantially does not contain particles with a particle size of 0.300μm or more, and the particle-containing surface layer contains particles with an average particle size of 0.005μm to 0.150μm.

Description

Polyester film for dry film anticorrosive agent, method for producing the same, and photosensitive laminate

The present invention relates to a polyester film used in the formation of a dry film resist (hereinafter sometimes referred to as "DFR"), and more particularly to a polyester film that can be preferably used as a support film constituting the dry film resist.

Dry film resist (DFR) is widely used as an anti-etching agent for forming wiring patterns on electronic circuit boards.

Dry film resist (DFR) is usually composed of three layers: support film (also called "carrier film")/photoresist layer containing photosensitive resin material/protective film (also called "cover film").

As a method for manufacturing an electronic circuit substrate using the DFR, for example, the protective film is first peeled off from the DFR to expose the photoresist layer, and the photoresist layer is superimposed on the copper layer surface of an epoxy resin substrate on which a copper layer is laminated, and the DFR is attached. Then, a support film is superimposed on a glass plate with a printed circuit and the DFR is brought into close contact, and light is irradiated from the glass plate side.

The light passes through the transparent part and the supporting film layer in the image of the circuit printed on the glass plate, and then irradiates the photoresist layer, and the part irradiated by the light in the photoresist layer is hardened by the light.

Next, after removing the glass plate and the support film, remove the uncured portion of the photoresist layer and perform etching using acid or the like.

At this time, the uncured portion of the photoresist layer is removed to expose the copper layer at the corresponding portion, and the exposed copper layer is removed from the epoxy substrate by etching to form a circuit on the epoxy substrate.

Furthermore, by removing the hardened photoresist layer, electronic circuit substrates can be manufactured.

As the support film used in the formation of DFR, polyester film is mainly used due to its excellent mechanical properties, optical properties, chemical resistance, heat resistance, dimensional stability, flatness, etc.

Regarding this type of polyester film, for example, Patent Document 1 discloses a biaxially oriented multilayer polyester film, which contains particles with an average particle size of 0.01μm to 3.0μm on at least one side of the outermost layer, and the centerline average roughness Ra of the outermost layer is greater than 0.005μm and the maximum height Rt is less than 1.5μm, and the haze value is set to less than 1.5%.

Patent document 2 discloses a laminated polyester film for a dry film anti-etching agent, which has excellent rollability, can more reliably prevent the occurrence of circuit defects and can further improve the resolution. The laminated polyester film comprises at least two polyester layers, the number of metal-containing agglomerates having a length of 10 μm or more is 5/10 cm _- ² or less, the outermost layer of at least one of the layers contains particles having an average particle size of 0.01 μm to 3.0 μm, the center line average roughness Ra of the surface is 0.002 μm to 0.030 μm and the maximum height Rt is 0.05 μm to 1.0 μm.

Patent document 3 discloses a biaxially aligned polyester film for a dry film anticorrosive agent support, wherein the number of pit defects with a depth of 0.5 μm or more is 5 or less/ ^m2 , the F-5 value in the length direction is 70 MPa to 150 MPa, the F-5 value in the width direction is 80 MPa to 160 MPa, the haze value is less than 1%, and the thermal shrinkage rate at 150°C for 30 minutes is 1.5% to 3.5% in the length direction and 0.5% to 2.5% in the width direction.

[Prior art literature] [Patent Literature]

Patent document 1: Japanese Patent Publication No. 7-333853

Patent document 2: Japanese Patent Publication No. 2005-77646

Patent document 3: Japanese Patent Publication No. 2008-239743

In recent years, due to the miniaturization of electronic devices, the circuits formed have become extremely complex, the lines have become thinner, and the intervals between them have also become narrower, requiring DFR to have higher reproducibility and resolution in image formation.

In DFR, light is irradiated to the photoresist layer through a support film for exposure. Therefore, if the transparency of the support film is low, the photoresist layer cannot be fully exposed. In addition, if the haze value of the film is high or the surface is rough, the resolution may deteriorate due to light scattering on the surface and inside of the film.

Therefore, the support film constituting DFR is required to have a flatter surface and higher transparency.

However, if the flatness of the film becomes higher, not only will the film's sliding and handling properties deteriorate, but it may also be difficult to roll up into a roll.

Furthermore, if the flatness is improved, when uneven thickness occurs in the width direction of the film, air is easily accumulated, which also becomes the cause of wrinkles.

In order to improve the handling and winding properties of the film, it is considered to contain particles in the polyester film and form fine protrusions on the surface.

However, if protrusions are formed by adding particles, the scattering of ultraviolet rays caused by the protrusions or the formation of depressions on the surface of the anti-etching agent will cause a decrease in resolution or defects in the formation of extremely fine circuits, and the transparency of the film will be easily reduced.

Thus, there is no method for obtaining a DFR film that satisfies transparency, flatness, slippage, and thickness uniformity in the width direction at the same time.

Therefore, the present invention relates to a polyester film used in forming a DFR, and in particular, to a polyester film that can be preferably used as a support film, and provides a new polyester film for dry film anti-corrosion agent, which can not only achieve high flatness and transparency, but also has good film slippage, less uneven thickness in the width direction of the film, can be rolled up, and at this time, air can be prevented from being enclosed between the films.

The present invention provides a polyester film for dry film anticorrosive, which has a surface layer containing particles on at least one side of a base polyester film having an inherent viscosity of 0.65 dl/g or more. The polyester film for dry film anticorrosive is characterized in that the base polyester film is a single layer composed of a polyester layer (also referred to as "A layer") or a multi-layer film having the A layer on the surface, the polyester layer contains particles with an average particle size of 0.030μm to 0.200μm at a mass ratio of 10ppm to 7000ppm, and substantially does not contain particles with a particle size of 0.300μm or more, and the particle-containing surface layer contains particles with an average particle size of 0.005μm to 0.150μm.

The polyester film for dry film anticorrosive agent proposed in the present invention has a high inherent viscosity of the base polyester film, so the stretching ratio, especially the stretching ratio in the width direction, can be increased, and the thickness unevenness in the width direction of the film can be reduced.

As a result, the thickness of the film can be made uniform, preventing air accumulation when it is rolled into a roll, thereby reducing the occurrence of wrinkles.

Furthermore, the polyester film for dry film anticorrosive agent proposed in the present invention has a polyester layer (A layer) containing particles with an average particle size of 0.030μm to 0.200μm at a mass ratio of 10ppm to 7000ppm, and a particle-containing surface layer containing particles with an average particle size of 0.005μm to 0.150μm, so that not only high flatness and transparency can be achieved, but also the slipperiness of the film can be improved, so it can be rolled up.

In addition, it can reduce film damage and eliminate the problem of anti-corrosion agent curing hindrance when used as a support film for dry film anti-corrosion agent.

Next, the present invention is described based on examples of implementation forms. However, the present invention is not limited to the implementation forms described below.

[This polyester film]

The polyester film for dry film anticorrosive agent (referred to as "the polyester film") as an example of an embodiment of the present invention is a polyester film having a surface layer containing particles on at least one side of a base polyester film.

<Polyester film as base material>

The base polyester film constituting the present polyester film (referred to as "the present base polyester film") is preferably a single layer consisting of a polyester layer (A layer) or a multilayer having the A layer on the surface, specifically a film consisting of two layers, three layers, four layers or more layers, wherein the polyester layer contains polyester as a main component resin and contains particles with an average particle size of 0.030μm to 0.200μm at a mass ratio of 10ppm to 7000ppm, and substantially does not contain particles with a particle size of 0.300μm or more.

When the base polyester film is a multi-layer film having a layer A on the surface, the main component resin of each layer other than the layer A is preferably a polyester, and the same polyester as the main component resin of the layer A is particularly preferred. Polyester will be described later.

At this time, the so-called "main component resin" means the resin with the highest content among the resins constituting each layer, and specifically means that the content of the resin in each layer is 50% by mass or more, preferably 80% by mass or more, and even more preferably 90% by mass or more.

In the case where the base polyester film is a multi-layer film having an A layer on the surface, specifically, A layer/B layer, A layer/B layer/A layer, etc. having a polyester layer (also called "B layer") as the main layer can be listed. Furthermore, A layer/B layer/C layer, A layer/B layer/C layer/A layer, etc. having a different polyester layer (also called "C layer") can also be listed. However, it is not limited to these.

(Layer A)

Layer A is a polyester layer that contains the polyester described below as the main component resin, contains particles with a particle size of 0.030μm to 0.200μm at a mass ratio of 10ppm to 7000ppm, and substantially does not contain particles with a particle size of 0.300μm or more.

If the A layer constituting the single layer of the present base polyester film, or the A layer as the single surface layer or double surface layers of the present base polyester film does not contain the above particles, not only the handling property is poor, but also there is a possibility that many scratches will be generated on the film surface during the film-forming step of the polyester film.

As described above, the anti-etching agent layer is exposed by irradiating light through the support film, so if there are foreign matter or scratches on the support film of the DFR, the said part will not be exposed and circuit defects will occur.

Therefore, if the polyester film is used as a support film for DFR, it is particularly preferred that the A layer forming the surface of the polyester film of the base material contains particles.

The average particle size of the particles contained in layer A is preferably in the range of 0.030μm~0.200μm.

If the average particle size of the particles is less than 0.200 μm, the transparency of the film will not be hindered. On the other hand, if the average particle size of the particles is greater than 0.030 μm, the surface of the film can be appropriately roughened, which not only improves the operability but also prevents the film surface from being scratched during the film-making step of the base polyester film.

From this point of view, the average particle size of the particles contained in the A layer is preferably 0.030μm~0.200μm, and is particularly preferably in the range of 0.040μm or more or 0.150μm or less, and is particularly preferably in the range of 0.050μm or more or 0.100μm or less.

Therefore, the average particle size of the particles contained in layer A is preferably 0.030μm~0.150μm or 0.030μm~0.100μm, more preferably 0.040μm~0.200μm, 0.040μm~0.150μm or 0.040μm~0.100μm, and particularly preferably 0.050μm~0.200μm, 0.050μm~0.150μm or 0.050μm~0.100μm.

Furthermore, the average particle size of the particles in each layer can be determined by measuring the diameters of more than 10 particles using a scanning electron microscope (SEM) and taking the average value thereof. In the case of non-spherical particles, the average value of the longest diameter and the shortest diameter can be taken as the diameter of each particle.

Furthermore, from the perspective of maintaining the transmittance of light during exposure and eliminating circuit defects after exposure, it is preferred that the A layer substantially does not contain particles with a particle size of 0.300μm or more.

At this time, the so-called "substantially not containing" means the intention not to contain, specifically, it means that the content (mass) of the particles is less than 200ppm, preferably less than 150ppm.

Furthermore, the A layer preferably contains particles with an average particle size of 0.030μm to 0.200μm at a mass ratio (also referred to as "concentration") of 10ppm to 7000ppm.

In layer A, if the content (particle concentration) of particles with an average particle size of 0.030μm to 0.200μm is less than 7000ppm, the transparency of the film can be improved. On the other hand, if the content (particle concentration) of particles with an average particle size of 0.030μm to 0.200μm is more than 10ppm, the surface of the film can be appropriately roughened, which not only improves the workability, but also prevents the film surface from being scratched during the film-making step of the base polyester film.

From this point of view, the A layer preferably contains particles with an average particle size of 0.030μm to 0.200μm at a mass ratio of 10ppm to 7000ppm, more preferably 100ppm or more or 6000ppm or less, more preferably 500ppm or more or 5000ppm or less, more preferably 1000ppm or more or 4000ppm or less.

Therefore, the A layer preferably contains particles with an average particle size of 0.030μm to 0.200μm at a mass ratio of 10ppm to 6000ppm, 10ppm to 5000ppm or 10ppm to 4000ppm, more preferably at a mass ratio of 100ppm to 7000ppm, 100ppm to 6000ppm, 100ppm to 5000ppm or 100ppm to 4000ppm, further preferably at a mass ratio of 500ppm to 7000ppm, 500ppm to 6000ppm, 500ppm to 5000ppm or 500ppm to 4000ppm, and particularly preferably at a mass ratio of 1000ppm to 7000ppm, 1000ppm to 6000ppm, 1000ppm to 5000ppm or 1000ppm to 4000ppm.

The particles contained in layer A are not particularly limited in material as long as they have an average particle size of 0.030μm to 0.200μm. Examples include inorganic particles such as calcium carbonate, calcium phosphate, silicon dioxide, kaolin, talc, titanium dioxide, aluminum oxide, barium sulfate, calcium fluoride, lithium fluoride, zeolite, and molybdenum sulfide, organic particles such as ion exchange resins, crosslinked polymers, and calcium oxalate, and precipitated particles generated during polyester polymerization.

The particles contained in layer A can be one type or two or more types, and particles of different particle sizes and shapes can be used simultaneously in the same type of particles.

In addition, the shape of the particles can be spherical, block-shaped, rod-shaped, flat, or any other shape.

From the perspective of transparency, the thickness of layer A is preferably 0.1μm to 20.0μm, more preferably 0.3μm or more or 10.0μm or less, more preferably 0.5μm or more or 5.0μm or less.

In addition, from the perspective of flatness, the ratio of the thickness (μm) of the A layer to the average particle size (μm) of the particles contained in the A layer is preferably 0.5 to 400, preferably 5 or more or 100 or less, and more preferably 10 or more or 50 or less.

(B layer)

The base polyester film preferably has a polyester layer (B layer) as a main layer in addition to the A layer. In this case, in order to reduce costs and improve transparency, the B layer preferably contains no particles substantially or at least contains particles at a lower concentration than the A layer.

At this time, the so-called "main layer" refers to the thickest layer among them when the base polyester film has other layers besides layer A.

In addition, the so-called "substantially not containing" means the intention not to contain, specifically, the particle content (particle mass concentration) is less than 200 ppm, preferably less than 150 ppm.

The polyester used as the main component resin of the B layer is preferably the same polyester as the main component resin of the A layer.

When the B layer contains particles, as described above, in order to suppress costs and improve transparency, the average particle size of the particles contained in the B layer is preferably smaller than the average particle size of the particles contained in the A layer, and is further preferably 0.010μm to 0.200μm, and is particularly preferably 0.012μm or more or 0.100μm or less, and is particularly preferably 0.015μm or more or 0.080μm or less.

In addition, from the perspective of maintaining the transmittance of light during exposure and eliminating circuit defects after exposure, the B layer is also preferably substantially free of particles with a particle size of 0.300μm or more, similar to the A layer.

Furthermore, as described above, in order to suppress costs and improve transparency, the particle concentration in the B layer is preferably at least lower than the particle concentration in the A layer, and specifically, it is preferably a mass ratio of 0ppm to 4000ppm, preferably less than 2000ppm, preferably less than 1000ppm, preferably less than 500ppm, and most preferably less than 100ppm.

In addition, the types and shapes of particles contained in layer B are the same as those in layer A.

Regarding the thickness of the B layer, from the perspective of improving transparency and reducing costs, the thickness of each A layer relative to the thickness of the B layer is preferably 0.1% to 40.0%, more preferably 1.0% or more or 20.0% or less, more preferably 3.0% or more or 10.0% or less.

(Layer C)

As described above, when the base polyester film has a C layer in addition to the A layer and the B layer, the C layer preferably has polyester as a main component resin and contains particles at least at a lower concentration than the A layer. Alternatively, it may contain particles like the A layer and may be a layer with a different thickness from the A layer.

Furthermore, the type and shape of particles in layer C are the same as those in layer A.

Regarding the thickness of the C layer, from the perspective of improving transparency and reducing costs, the thickness of the C layer relative to the thickness of the A layer is preferably 1% to 300%, more preferably 10% or more or 200% or less, more preferably 20% or more or 150% or less.

(Polyester)

The polyester constituting the main component resin of each layer of the polyester film of this substrate is not particularly limited, as long as it is a polyester obtained by using aromatic dicarboxylic acid or its ester and glycol as the main starting materials. Among them, it is preferred that more than 60% of the repeating structural units are polyesters having ethylene terephthalate units or ethylene-2,6-naphthalene units.

In addition, the polyester may contain a third component other than the ethylene terephthalate unit or the ethylene-2,6-naphthalene unit as a copolymer 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-naphthalene dicarboxylic acid, isophthalic acid, phthalic acid, adipic acid, sebacic acid, etc. Terephthalic acid or dimethyl terephthalate is particularly preferred.

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

When the polyester is a copolyester, the dicarboxylic acid component thereof may include one or more of isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalene dicarboxylic acid, sebacic acid, etc., and the glycol component may include one or more of ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, etc.

(Polyester film as base material)

The base polyester film preferably has an inherent viscosity of 0.65 dl/g or more.

If the inherent viscosity of the base polyester film is 0.65 dl/g or more, as described later, even if the stretching ratio, especially the stretching ratio in the width direction (transverse direction), is increased to 4.0 times or more, it can be stretched without causing breakage, so that the uneven thickness of the film in the width direction can be reduced, and air accumulation can be suppressed when the film is rolled up, thereby reducing the occurrence of wrinkles.

From this point of view, the inherent viscosity of the polyester film of the present substrate is preferably 0.65 dl/g or more, more preferably 0.65 dl/g or more or 0.90 dl/g or less, more preferably 0.66 dl/g or more or 0.80 dl/g or less.

The inherent viscosity of the polyester film of this base material can be adjusted by appropriately changing the polymerization conditions of the polyester as the main component resin. For example, the inherent viscosity can be increased by extending the polymerization time or by using solid phase polymerization to increase the molecular weight.

Furthermore, in the case of the laminated polyester film of the present substrate, the inherent viscosity refers to the inherent viscosity of all layers of the film.

The base polyester film can be an unstretched film (sheet) or a stretched film. Among them, a stretched film is preferred, and a biaxially stretched film is more preferred.

When the laminated polyester film is a biaxially stretched film, it can be a sequentially secondary stretched film or a simultaneously biaxially stretched film.

From the perspective of operability and economy, the thickness of the base polyester film is preferably 6μm to 63μm, more preferably 9μm or more or 38μm or less, more preferably 12μm or more or 25μm or less.

<Surface layer containing particles>

The polyester film may be a structure in which a surface layer containing particles is laminated only on one side of a base polyester film, or may be a structure in which surface layers containing particles are laminated on both sides of a base polyester film.

Furthermore, other layers may be layered between the base polyester film and the particle-containing surface layer, or on the surface of the particle-containing surface layer.

Furthermore, when the base polyester film includes two layers, namely, layer A and layer B, and when the particle-containing surface layer is formed only on one side of the base polyester film, it is preferred to form the particle-containing surface layer on the opposite side of layer A, i.e., layer B.

The particle-containing surface layer preferably contains particles with an average particle size of 0.005μm~0.150μm.

If the average particle size of the particles contained in the particle-containing surface layer is 0.005 μm or more, the slip and winding properties of the film can be better maintained. If the average particle size is 0.150 μm or less, the particles are difficult to fall off from the particle-containing surface layer. In addition, the particle-containing surface layer is difficult to cut, so it is better.

From this point of view, the particle-containing surface layer preferably contains particles with an average particle size of 0.005μm to 0.150μm, preferably containing particles with a particle size of 0.010μm or more or 0.120μm or less, and preferably containing particles with a particle size of 0.030μm or more or 0.100μm or less.

Therefore, the particle-containing surface layer preferably contains particles of 0.005μm~0.120μm or 0.005μm~0.100μm, more preferably particles of 0.010μm~0.150μm, 0.010μm~0.120μm or 0.010μm~0.100μm, and particularly preferably particles of 0.030μm~0.150μm, 0.030μm~0.120μm or 0.030μm~0.100μm.

Furthermore, if the average particle size of the particles contained in the particle-containing surface layer is within the above range, the particle-containing surface layer may contain particles with a particle size less than 0.005 μm, and may also contain particles with a particle size greater than 0.150 μm.

The ratio of the average particle size of the particles contained in the particle-containing surface layer to the average particle size of the particles contained in the A layer is preferably 0.02 to 10, more preferably 0.1 or more or 5 or less, more preferably 0.3 or more or 3 or less, and more preferably the average particle size of the particles contained in the particle-containing surface layer is larger than the average particle size of the particles contained in the A layer.

By satisfying the prescribed range of the ratio, the flatness of the A layer and the slipperiness of the particle-containing surface layer can be simultaneously satisfied, and a better DFR film can be obtained.

The average particle size of particles in the surface layer containing particles can be determined by measuring the diameters of 10 or more particles using a scanning electron microscope (SEM) and taking the average value thereof. In the case of non-spherical particles, the average value of the longest diameter and the shortest diameter can be taken as the diameter of each particle.

The particle concentration in the particle-containing surface layer is preferably 1 mass% to 10 mass%.

If the particle concentration in the particle-containing surface layer is 1% by mass or more, it can provide lubricity and winding improvement effects. On the other hand, if it is 10% by mass or less, the particles are difficult to aggregate, which can reduce the cutting of the particle-containing surface layer caused by particle shedding, and it is difficult to block the light transmission of the DFR film, and it is difficult to cause circuit defects.

From this viewpoint, the particle concentration in the particle-containing surface layer is preferably 1 mass% to 10 mass%, more preferably 2 mass% or more or 7 mass% or less, more preferably 2 mass% or more or 5 mass% or less.

The ratio of the particle concentration (mass %) in the particle-containing surface layer to the particle concentration (mass %) in the A layer is preferably 1 to 10000, preferably 5 or more or 1000 or less, preferably 10 or more or 100 or less.

By satisfying the specified range of the ratio, the flatness and damage resistance of the A layer and the slipperiness of the particle-containing surface layer can be satisfied at the same time, and a better DFR film can be obtained.

The types and shapes of particles in the particle-containing surface layer are the same as those described for the particles contained in the A layer. Among them, inorganic particles are preferred, and silica particles are preferred.

(Antistatic Agent)

The particle-containing surface layer preferably further contains an antistatic agent.

When the support film pressed onto the photoresist layer is peeled off, foreign matter such as garbage or dust is attracted and attached to the photoresist layer by static electricity generated by the stripping charge, which sometimes causes irregular circuit patterns. Therefore, it is better to give the support film anti-static performance when peeling off.

Since the particle-containing surface layer contains an antistatic agent, the polyester film can be made into a support film for a high-resolution dry film anti-corrosion agent having a highly flat surface in contact with the photoresist layer and having mold release and antistatic properties.

The antistatic agent used in the particle-containing surface layer may include, for example, ammonium-containing compounds, polyether compounds, sulfonic acid compounds, betaine compounds and other ion-conductive polymer compounds, or polyacetylene, polyphenylene, polyaniline, polypyrrole, polyisothianaphthene, polythiophene and other π-electron conjugated polymer compounds. Furthermore, the polyether compound is an antistatic agent, which is also equivalent to the synthetic wax used as the release agent.

Among these, ion-conductive polymer compounds are preferred, and ammonium-containing compounds are particularly preferred. The particle-containing surface layer formed by a coating liquid containing π-conjugated conductive polymers, such as polythiophene and polyaniline, generally has a strong color. The DFR film preferably has high transparency (low haze), so π-conjugated conductive polymers are sometimes not suitable.

In addition, π-conjugated conductive polymer coatings are generally more expensive than ion conductive coatings, so from the perspective of manufacturing cost, it is also better to use ion conductive antistatic agents.

As the ammonium-containing compound, a polymer compound having an ammonium group is preferred. 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 the polymer, for example, a polymer having the constituent elements represented by the following formula (1) as repeating units can be cited. It can also be a copolymer obtained by copolymerizing the homopolymer or other multiple components.

In the formula (1), R ¹ and R ² are independently a hydrogen atom, an alkyl group, a phenyl group, etc. These alkyl groups and phenyl groups may be substituted by the following groups.

Substitutable groups include, for example, hydroxyl, amide, ester, alkoxy, phenoxy, naphthoxy, thioalkoxy, thiophenoxy, cycloalkyl, trialkylammoniumalkyl, cyano, halogen, etc. In addition, ^R1 and ^R2 may be chemically bonded, for example, -( _CH2 ) _m- (m=integer of 2 to 5), -CH( _CH3 )CH( _CH3 )-, _-CH =CH-CH=CH-, -CH=CH-CH=N-, -CH=CH-N=C-, _{-CH2OCH2-, -(CH2)2O ( CH2 ) 2-} , etc.

In the case of a polymer having the constituent element represented by the above formula (1) as a repeating unit, it is preferred to copolymerize with other repeating units from the viewpoint of improving compatibility with other materials, improving the transparency of the resulting coating, or further improving the demolding property. Examples of other repeating units include: alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, and butyl acrylate, alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate, and acrylamides such as n-hydroxymethylacrylamide.

^X- in the formula (1) can be appropriately selected within the scope that does not impair the gist of the present invention. For example, halogen ions, sulfonates, phosphates, nitrates, alkylsulfonates, carboxylates, etc. can be listed.

In addition, the polymer formed by copolymerization of the constituent elements represented by formula (1) and (meth)acrylate containing polyethylene glycol has a soft structure, and a particle-containing surface layer with excellent uniformity can be obtained during inline coating, so it is preferred.

The number average molecular weight of the antistatic agent contained in the particle-containing surface layer is preferably 1,000 to 500,000, more preferably 2,000 or more or 350,000 or less, more preferably 5,000 or more or 200,000 or less.

If the number average molecular weight of the antistatic agent is 1,000 or more, the strength of the coating can be maintained, and the heat resistance stability can be maintained, and sufficient antistatic properties can be obtained. In addition, if the molecular weight is 500,000 or less, the viscosity of the coating liquid can be prevented from increasing, and the operability or coating properties can be well maintained, making it suitable as a DFR film.

(wax)

In order to improve the slipperiness of the film, the particle-containing surface layer preferably contains wax.

At this time, it may be contained together with the antistatic agent, or it may not contain the antistatic agent but contain wax.

Examples of waxes that may be contained in the particle-containing surface layer include natural waxes such as plant-based waxes, animal-based waxes, mineral-based waxes, and petroleum waxes, and synthetic waxes such as synthetic hydrocarbons, modified waxes, and hydrogenated waxes.

Among them, polyolefin compounds are preferred. Specifically, compounds having a basic skeleton such as a polyolefin compound composed of a polymer or copolymer of unsaturated hydrocarbons such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, etc. can be dissolved or dispersed, and examples thereof include polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene copolymer, ethylene-1-butene copolymer, propylene-1-butene copolymer, etc. More specifically, it is preferred to use a polyolefin having an acid value of 10 to 50 with an active hydrogen group at the end, and further preferably, oxidized polyethylene or oxidized polypropylene.

When using polymer wax, the number average molecular weight is preferably 2000~20000, and more preferably 3000~15000. If it is within these ranges, the film-forming property and mold release property can be maintained.

In addition, the softening point is preferably 70°C to 170°C, and more preferably above 90°C or below 150°C. If it is within these ranges, the film-forming property and demolding property can be maintained.

(Crosslinking agent)

In order to improve the coating strength of the particle-containing surface layer and impart wear resistance to the film, the particle-containing surface layer preferably further contains a crosslinking agent.

As crosslinking agents, for example, melamine compounds, oxazoline compounds, epoxy compounds, isocyanate compounds, carbodiimide compounds, etc. can be cited. Among these crosslinking agents, melamine compounds are preferred from the viewpoint of good coating strength and excellent demolding properties of the particle-containing surface layer.

In addition, two or more of these crosslinking agents may be used in combination.

The so-called melamine compound is a compound having a melamine skeleton in the compound, for example, an alkyl alcoholized melamine derivative, a compound partially or completely etherified by reacting an alcohol with an alkyl alcoholized melamine derivative, and a mixture thereof. As the alcohol used for etherification, methanol, ethanol, isopropanol, n-butanol, isobutanol, etc. can be preferably used.

In addition, the melamine compound may be a monomer or a polymer having a dimer or higher, or a mixture thereof may be used.

Furthermore, a compound in which urea or the like is co-condensed with a portion of melamine may be used, and a catalyst may be used to increase the reactivity of the melamine compound.

As the oxazoline compound, a polymer containing an oxazoline group is particularly preferred, which can be prepared by polymerization with a monomer containing an addition-polymerizable oxazoline group alone or with other monomers. Monomers containing an addition-polymerizable oxazoline group include: 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazolyl, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline, etc., and one or a mixture of two or more of these can be used.

Other monomers are not limited as long as they are monomers copolymerizable with the monomer containing an addition polymerizable oxazoline group. Examples thereof include: (meth)acrylates such as alkyl (meth)acrylates (methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, 2-ethylhexyl, and cyclohexyl as the alkyl group); unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, styrenesulfonic 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 ( Unsaturated amides such as (methyl)acrylamide, N,N-dialkyl (meth)acrylamide (methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, 2-ethylhexyl, cyclohexyl, etc. as alkyl); 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; α,β-unsaturated monomers containing halogens such as vinyl chloride and vinylidene chloride; α,β-unsaturated aromatic monomers such as styrene and α-methylstyrene, etc., and one or more of these monomers can be used.

Examples of the epoxy compounds include condensates of epichlorohydrin with ethylene glycol, polyethylene glycol, glycerol, polyglycerol, bisphenol A and other hydroxyl or amino groups, polyepoxides, diepoxides, monoepoxides, glycidylamine compounds, etc.

Examples of the polyepoxide include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyl tri(2-hydroxyethyl)isocyanate, glycerol polyglycidyl ether, and trihydroxymethylpropane polyglycidyl ether. Examples of the diepoxide include neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, resorcinol diglycidyl ether, and ethylene glycol diglycidyl ether. Glycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polybutylene glycol diglycidyl ether, as monoepoxy compounds, for example, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether can be listed, as glycidylamine compounds, N,N,N',N'-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N-diglycidylamino)cyclohexane, etc. can be listed.

Furthermore, the crosslinking agent is preferably used in a design that allows it to react during a drying process or a film-forming process to improve the performance of the particle-containing surface layer. It can be inferred that unreacted products of these crosslinking agents, reacted compounds, or mixtures thereof exist in the formed particle-containing surface layer.

(Adhesive)

In order to improve the adhesion to the polyester film of the present substrate, the particle-containing surface layer may also contain thermoplastic resins such as polyesters, polyurethanes, acrylic resins, polyethylene resins, polyolefins, and/or thermosetting resins such as thermosetting acrylic resins, melamine resins, and epoxy resins as adhesives.

(Content ratio)

The quality of the particles contained in the particle-containing surface layer and the antistatic agent, wax, adhesive and crosslinking agent that the particle-containing surface layer may further have are preferably adjusted appropriately according to the selected compound, as described below as a standard.

The content of particles in the particle-containing surface layer (particle concentration) is preferably 1% by mass or more, and more preferably 2% by mass or more or 10% by mass or less.

By setting the particle content (particle concentration) in the particle-containing surface layer to 1% by mass or more, it is easy to obtain the effect of improving the slip and winding of the DFR film. By setting it to 10% by mass or less, the particles are difficult to aggregate, which can reduce the cutting of the particle-containing surface layer caused by particle shedding, and it is difficult to block the light transmission of the DFR film, and it is difficult to produce circuit defects.

The content of the antistatic agent in the particle-containing surface 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, the content is preferably 15% to 90% by mass, and more preferably 20% by mass or more or 90% by mass or less.

By keeping the antistatic agent content within the above range, sufficient surface specific resistance can be achieved, and the DFR film is unlikely to be electrostatically bonded.

The wax content in the particle-containing surface 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 within the above range, it is easy to achieve a sufficient slippery effect and it is difficult to hinder the adhesion with the polyester film substrate.

The content of the crosslinking agent in the particle-containing surface layer forming composition constituting the particle-containing surface layer is preferably 1% by mass or more, and more preferably 2% by mass or more or 50% by mass or less.

By making the crosslinking agent content 1% by mass or more, it is easy to obtain the effect of improving the slip and winding of the DFR film. By making it 50% by mass or less, it is difficult to block the light transmission of the DFR film and it is difficult to produce circuit defects.

The content of the adhesive in the particle-containing surface 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 adhesive is within the above range, sufficient adhesion to the polyester film substrate can be obtained.

(Other ingredients)

The surface layer containing particles may also be used with defoamers, coating improvers, viscosity enhancers, organic lubricants, antistatic agents, UV absorbers, antioxidants, foaming agents, dyes, pigments, etc. as needed.

The analysis of the composition of the surface layer containing particles can be performed, for example, by time of flight secondary ion mass spectrometry (TOF-SIMS), X-ray photoelectron spectroscopy (XPS), fluorescent X-ray analysis, etc.

(Thickness of the surface layer containing particles)

The film thickness of the particle-containing surface layer is preferably 0.001μm to 0.5μm, more preferably 0.005μm or more or 0.3μm or less, more preferably 0.01μm or more or 0.2μm or less.

If the film thickness of the surface layer containing particles is 0.5μm or less, the appearance of the coating or the curing state of the coating can be maintained, and if the film thickness is 0.001μm or more, sufficient mold release properties can be obtained.

In addition, if the film thickness of the surface layer containing particles is 0.001μm~0.5μm, it will not affect the surface roughness of the laminated polyester film.

That is, the surface roughness of the dry film anticorrosive film can be considered to be the same as the surface roughness of the laminated polyester film.

The ratio of the film thickness (μm) of the particle-containing surface layer to the average particle size (μm) of the particles contained in the particle-containing surface layer is preferably 0.005 to 100.

If the ratio is 0.005 or more, the particles can be prevented from falling off. On the other hand, if it is 100 or less, the surface protrusions caused by the particles can be maintained, so the sliding property can be further improved, and the rolling property can be improved.

From this point of view, the ratio is preferably 0.005 to 100, preferably 0.01 or more or 10 or less, and more preferably 0.1 or more or 1 or less.

In addition, the ratio of the film thickness (μm) of the particle-containing surface layer to the layer thickness (μm) of the A layer is preferably 0.00005 to 5, preferably 0.001 or more or 1 or less, and more preferably 0.01 or more or 0.1 or less.

<Method for producing the polyester film>

(Method for producing the polyester film as a base material)

First, the method for producing the base polyester film is described.

For example, raw materials such as polyester resin are melted in an extruder, and all layers of a mold (such as a T-mold, etc.) are co-melted and extruded from the die opening onto a rotating cooling drum, and then the unstretched laminated film is produced by stretching the unstretched laminated film in the longitudinal and transverse directions and heat-fixing as needed.

At this time, it is better to set the stretching ratio in the transverse direction, in other words, the width direction, to 4.0 times or more, and it is better to set the stretching ratio in the longitudinal direction to 2.5 times or more as needed.

The inherent viscosity of the polyester film of this substrate is above 0.65dl/g, so it can be implemented under the condition that the high-ratio stretching, especially the stretching in the lateral direction, is not interrupted, which can reduce the uneven thickness and make the thickness uniform, thereby preventing the accumulation of air when winding into a roll, thereby suppressing the occurrence of wrinkles.

An example of a method for producing the present base polyester film including three layers of layer A/layer B/layer A is described. The other layer structures are the same.

First, the polyester forming the A layer and the polyester forming the B layer are supplied to respective extruders, heated to a temperature above the melting point of each polyester, and melted separately. Then, in order to layer each polyester in the order of A/B/A, it is extruded from a T die as a sheet.

Next, the sheet is quenched on a rotating cooling drum to a temperature below the glass transition temperature 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 rotating cooling drum can also be improved by electrostatic bonding or liquid coating bonding.

Next, a roll stretching machine is used to stretch the unstretched film in its length direction (longitudinal stretching) to obtain a uniaxially stretched film. At this time, the stretching temperature is above the glass transition temperature of polyester, preferably 70°C to 150°C, and more preferably 75°C to 130°C. In addition, the longitudinal stretching ratio is 2.5 times or more, 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 can be performed in only one stage, or it can be divided into two or more stages.

Next, a tenter stretching machine is used to stretch the uniaxially stretched film in its width direction (transverse stretching) to obtain a biaxially stretched film. At this time, the stretching temperature is preferably 75°C to 150°C, and more preferably 80°C to 140°C. In addition, the transverse stretching ratio is preferably set to 4.0 times or more, preferably 4.2 times or more or 6.0 times or less, preferably 4.4 times or more or 5.5 times or less, and further preferably 4.5 times or more or 5.0 times or less. At this time, transverse stretching can be performed in only one stage, or it can be divided into two or more stages.

Next, a laminated film is produced by heat treating the biaxially stretched film at a temperature of, for example, 150°C to 250°C.

When the biaxially stretched film is heat treated, the biaxially stretched film can also be relaxed within 30%.

Moreover, you can just roll it up as needed.

(Formation of a particle-containing surface layer)

The particle-containing surface layer can be formed by "in-line coating" in which the film surface is treated during the manufacturing step of the base polyester film, or by "off-line coating" in which the film surface is coated outside the system on the already manufactured base polyester film.

In-line coating is a method of coating during the manufacturing process of the base polyester film. Specifically, it is a method of coating at any stage after the polyester is melt-extruded, stretched, heat-fixed, and wound.

Usually, it is applied on any of the unstretched sheets obtained by melting and quenching, the stretched uniaxially stretched film, the biaxially stretched film before heat setting, and the film before winding after heat setting.

For example, in the sequential biaxial stretching, the method of stretching in the transverse direction after coating a uniaxially stretched film stretched in the longitudinal direction (longitudinal direction) is particularly excellent.

According to this method, film formation and particle-containing surface layer formation can be performed simultaneously, so it has an advantage in manufacturing cost.

In addition, in order to stretch after coating, the film thickness of the surface layer containing particles can be changed according to the stretching ratio, and the coating can be thinned more easily compared to off-line coating.

In addition, by providing a particle-containing surface layer on the base polyester film before stretching, the particle-containing surface layer can be stretched together with the base polyester film. This allows the particle-containing surface layer to be firmly bonded to the base polyester film.

Furthermore, in the production of biaxially stretched polyester film, the film can be constrained in the longitudinal and transverse directions by holding the film ends with a clip or the like and stretching it, and in the heat fixing step, high temperature can be applied while maintaining flatness without forming wrinkles or the like.

Therefore, the heat treatment performed after coating can be made high temperature which cannot be achieved by other methods, so the film forming property of the particle-containing surface layer is improved, and the particle-containing surface layer can be more firmly bonded to the base film.

Furthermore, a strong particle-containing surface layer can be formed, and the performance or durability of the particle-containing surface layer can be improved. Therefore, as a method for forming a particle-containing surface layer on at least one side of a polyester film, a manufacturing method in which a coating liquid is applied to the polyester film and then extended in at least one direction is preferred.

As a method for forming a particle-containing surface layer, for example, the particles and the particle-containing surface layer may further contain an antistatic agent, wax, adhesive, crosslinking agent, etc., are dispersed and dissolved in a solvent to prepare a particle-containing surface layer solution, and the solution is applied to one side of a base polyester film.

The particle-containing surface layer is preferably formed by applying a solution as an aqueous coating (a water-soluble resin or a water-dispersible resin using water as a medium) on one side of the base polyester film.

However, it can also be formed by applying an aqueous coating containing a small amount of organic solvent.

Examples of the organic solvent include alcohols such as ethanol, isopropyl alcohol, ethylene glycol, and glycerin, ethers such as ethyl solvent, tert-butyl solvent, propylene glycol monomethyl ether, and tetrahydrofuran, ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate, and amines such as dimethylethanolamine. These can be used alone or in combination. By appropriately selecting and including these organic solvents in the aqueous coating as needed, the stability, coating properties, or coating film properties of the coating can be improved.

As a method for coating a particle-containing surface layer with a solution on a polyester film substrate, for example, a reverse roll coater, gravure coater, rod coater, air knife coater, or coating devices other than those described in "Coating Methods" by Yuji Harasaki, published by Maki Shoten in 1979 can be used.

Regarding the drying and curing conditions when forming a particle-containing surface layer on the polyester film, for example, when the particle-containing surface layer is provided by off-line coating, it is generally advisable to perform heat treatment at 80°C to 200°C for 3 seconds to 40 seconds, preferably at 100°C to 180°C for 3 seconds to 40 seconds as a standard.

On the other hand, when a particle-containing surface layer is provided by in-line coating, it is generally appropriate to perform heat treatment at 70°C to 270°C for 3 seconds to 200 seconds as a standard.

In addition, regardless of off-line coating or in-line coating, heat treatment and active energy ray irradiation such as ultraviolet irradiation may be used together as needed. The surface of the laminated polyester film constituting the polyester film may be subjected to surface treatment such as corona treatment and plasma treatment in advance.

<This polyester film>

Next, the characteristics that this polyester film may have are described.

(Surface roughness)

The average surface roughness (Ra) of the surface of the polyester film is preferably in the range of 0.001μm to 0.020μm, more preferably 0.002μm or more and 0.010μm or less, more preferably 0.002μm or more or 0.005μm or less.

By making the surface roughness (Ra) of the polyester film within the above range, the transparency of the polyester film is not impaired, and the light scattering of the unevenness of the film surface is unlikely to increase, thereby suppressing the reduction of ultraviolet (UV) exposure and the resolution is unlikely to decrease.

Furthermore, when the particle-containing surface layer is formed only on one side, it is preferably formed on the side opposite to the side on which the photoresist layer of the base polyester film is formed, so the average surface roughness (Ra) is preferably the surface of the base polyester film, i.e., layer A.

The same applies to Rt described below.

The maximum surface roughness (Rt) of the polyester film is preferably in the range of 0.010μm to 0.400μm, more preferably 0.015μm or more or 0.300μm or less, more preferably 0.020μm or more or 0.200μm or less, more preferably 0.025μm or more or 0.100μm or less.

If the maximum surface roughness (Rt) of the polyester film is 0.400μm or less, the concavo-convex transfer in the photoresist layer can be prevented, and the problem of circuit defects can be eliminated when forming a fine-pitch circuit. On the other hand, if the average surface roughness (Ra) is 0.001μm or more or the maximum surface roughness (Rt) is 0.010μm or more, the steps are reasonable, and it is difficult to scratch the surface of the DFR film in the film-making step. Furthermore, it is difficult to produce damage transfer to the photoresist layer caused by the damage, exposure scattering, and it is difficult to affect the fine-pitch circuit pattern, so it is better.

(Fog)

When used for high-resolution DFR, the haze of the polyester film is preferably 1.0% or less, and more preferably 0.1% or more or 0.7% or less, and more preferably 0.2% or more or 0.5% or less, from the viewpoint that the exposure to ultraviolet light is unlikely to become insufficient, and defects in the required circuit are unlikely to be caused, and the reduction in resolution can be suppressed.

(Antistatic properties)

The polyester film of the present invention preferably has a surface specific resistance of 2.0×10 ¹³ Ω/□ or less, more preferably 1.0×10 ⁷ Ω/□ or more or 1.0×10 ¹² Ω/□ or less.

Since the surface specific resistance of the polyester film is 2.0×10 ¹³ Ω/□ or less, it is easy to control the peeling charge when the DFR is rolled into a roll.

Therefore, it is difficult to be charged, and the spark discharge caused by peeling charge can be suppressed. In addition, the adhesion of garbage and dust caused by charging can be prevented during the formation step of the photoresist layer, and the formation defects of the photoresist layer and foreign matter defects after UV exposure can be prevented. Especially in DFRs that require high resolution, even small and trace foreign matter may become a defect in the circuit, so it can be suppressed.

By forming the particle-containing surface layer, the lubricity can be improved, and by including an antistatic agent in the particle-containing surface layer, the antistatic property can be further improved.

<How to use this polyester film>

The polyester film can be preferably used as a support film for dry film anticorrosives. For example, by laminating a photoresist layer on at least one side of the polyester film as a support film, and laminating with a protective film as needed, a photosensitive laminate (such as DFR) can be formed.

Therefore, the photosensitive laminate (e.g., DFR) as an example of an embodiment of the present invention has a structure in which a photoresist layer is laminated on at least one side of the polyester film.

At this time, when the particle-containing surface layer is formed only on one side of the present base polyester film, in order to make the particle-containing surface layer located on the side opposite to the photoresist layer formation side when forming the DFR, in other words, in order to make the surface of the present base polyester film on the opposite side to the particle-containing surface layer, i.e., layer A, and the photoresist layer closely contact, it is preferred to press the present polyester film layer onto the photoresist layer.

Photosensitive laminates (such as DFR) usually have a laminated structure of support film/photoresist layer/protective film. When the DFR is rolled into a roll, the lower surface of the DFR, i.e., the support film, contacts the protective film on the upper surface.

Therefore, the lubricity effect of the surface layer containing particles on the surface in contact with the protective film becomes significant. In addition, since there is no surface layer containing particles on the anti-etching agent surface, the adhesion between the anti-etching agent and the supporting film is difficult to change, and it is difficult to cause peeling defects when removing the supporting film from the anti-etching agent.

The photoresist layer that constitutes the dry film resist is formed by a photosensitive resin material and hardens by reacting with light such as ultraviolet rays.

Specific examples of photosensitive resin materials include alkali-soluble polymers such as carboxylic acid-containing vinyl copolymers, ethylenically unsaturated addition-polymerizable monomers such as 2-hydroxy-3-phenoxypropyl acrylate, and photopolymerization initiators such as benzyl dimethyl ketal.

The protective film constituting the photosensitive laminate (such as DFR) is formed by polyolefins such as polyethylene and polypropylene, polyester, etc., and can protect the dry film anti-etching agent by being layered on the surface opposite to the laminate film in the photoresist layer.

<Explanation of sentences, etc.>

Generally speaking, the so-called "sheet" in the definition of Japanese Industrial Standards (JIS) refers to a thin, flat product whose thickness is small compared to the length and width; generally speaking, the so-called "film" refers to a thin and flat product whose thickness is extremely small compared to the length and width and the maximum thickness is arbitrarily limited, usually referring to a material supplied in the form of a roll (Japanese Industrial Standards JISK6900). However, the boundary between sheets and films is uncertain, and there is no need to distinguish between the two in terms of terminology in the present invention. Therefore, in the present invention, when it is called "film", it also includes "sheet", and when it is called "sheet", it also includes "film".

In addition, when the term "panel" is used for image display panels, protective panels, etc., it includes the plate body, sheet, and film.

In this manual, when "X~Y" (X and Y are arbitrary numbers) is recorded, unless otherwise specified, the meaning of "above X and below Y" also includes the meaning of "preferably greater than X" or "preferably less than Y".

In addition, when "X or more" (X is an arbitrary number) is written, it also includes the meaning of "preferably greater than X" unless otherwise specified, and when "Y or less" (Y is an arbitrary number) is written, it also includes the meaning of "preferably less than Y" unless otherwise specified.

[Implementation example]

The present invention is described in more detail below through examples. However, the present invention is not limited to the following examples as long as it does not exceed its main purpose.

<Material for forming base polyester>

In the embodiments and comparative examples, the following polyesters were used to make the base polyester (layer A, layer B).

(Polyester resin I)

100 parts by mass of dimethyl terephthalate and 60 parts by mass of ethylene glycol were used as starting materials. Tetra-n-butyl titanium ester was added in a manner such that the content in terms of titanium atoms became 10 ppm by mass concentration and was measured in the reactor. The reaction start temperature was set to 150°C. As methanol was distilled off, the reaction temperature was slowly increased to 230°C after 3 hours. After 4 hours, the transesterification reaction was substantially completed. The reaction mixture was transferred to a polycondensation tank and polycondensed for 4 hours. The polymer was sprayed out in a tangle state under nitrogen pressure, cooled and wafered to obtain polyester wafers. The polyester wafers were then solid-phase polymerized at 220°C under vacuum to obtain polyester resin I.

The inherent viscosity of polyester resin I is 0.70dl/g.

(Polyester resin II)

100 parts by mass of dimethyl terephthalate, 60 parts by mass of ethylene glycol and 0.09 parts by mass of magnesium acetate tetrahydrate were weighed in the reactor. As the temperature was raised, methanol was distilled off and the transesterification reaction was carried out. Here, it took 4 hours from the start of the reaction to raise the temperature to 230°C, which essentially ended the transesterification reaction.

Then, spherical aluminum oxide particles were added and ethylene glycol slurry was prepared and added. After the slurry was added, 0.03 parts by mass of phosphoric acid was further added, and antimony trioxide was added in such a manner that the content in terms of antimony atoms became 330 ppm by mass concentration, and a polycondensation reaction was carried out to obtain polyester resin II. The inherent viscosity of polyester resin II is 0.61 dl/g.

At this time, the spherical alumina particles do not contain particles with a particle size of 0.300 μm or more, and the content of the spherical alumina particles is 1.5% by mass relative to the entire polyester resin II.

(Polyester resin III)

In the preparation of polyester resin II, polyester resin III was obtained in the same manner as polyester resin II, except that irregular fine silica particles were added instead of spherical alumina particles. The inherent viscosity of polyester resin III was 0.61 dl/g.

At this time, the irregular fine silica particles do not contain particles with a particle size of 0.300 μm or more, and the content of the irregular fine silica particles is 0.3 mass % relative to the entire polyester resin III.

(Polyester resin IV)

In the preparation of polyester resin II, polyester resin IV was obtained in the same manner as polyester resin II except that ion exchange resin particles were added instead of spherical alumina particles. The inherent viscosity of polyester resin IV was 0.61 dl/g.

At this time, the ion exchange resin particles include particles with a particle size of 0.300 μm or more, and the content of the ion exchange resin particles is 0.5 mass % relative to the entire polyester resin IV.

(Polyester resin V)

In the preparation of polyester resin II, polyester resin V was obtained in the same manner as polyester resin II, except that spherical aluminum oxide particles were not added and the antimony trioxide content was set to 240 ppm by mass in terms of antimony atoms. The inherent viscosity of polyester resin V was 0.63 dl/g.

<Surface layer forming composition containing particles>

The following raw materials were used and mixed in the following examples and comparative examples at the mass ratios shown in the table to prepare a coating liquid as a particle-containing surface layer forming composition.

． Antistatic agent (A1)

Polydiallyldimethylammonium chloride (number average molecular weight: about 30,000)

．Wax (B1)

In an emulsifying device with a capacity of 1.5L and equipped with a stirrer, a thermometer, and a temperature controller, add 300g of oxidized polyethylene wax with a melting point (softening point) of 105°C, an acid value of 16mgKOH/g, a density of 0.93g/mL, and a number average molecular weight of 5,000, 650g of ion exchange water, 50g of monooleyl decaglycerol surfactant, and 10g of a 48% potassium hydroxide aqueous solution. After replacing under nitrogen, seal the device, stir at high speed at 150°C for 1 hour, cool to 130°C, pass through a high-pressure homogenizer at 400 atmospheres, and cool to a wax emulsion at 40°C.

． Particles (C1): Silica particles with an average particle size of 0.05μm

． Particles (C2): Silica particles with an average particle size of 0.08μm

In addition, the average particle size of particles (C1) and (C2) was obtained using a transmission electron microscope (H7650 manufactured by Hitachi High-technologies Co., Ltd., accelerating voltage 100 kV).

．Aqueous dispersion (D1)

An acrylic resin aqueous dispersion with a glass transition point of 40°C polymerized with the following composition: ethyl acrylate/n-butyl acrylate/methyl methacrylate/N-hydroxymethylacrylamide/acrylic acid = 65/21/10/2/2 (mass %) emulsified polymer (emulsifier: anionic surfactant)

． Crosslinking agent (E1): Hexamethoxyhydroxymethyl melamine

<Implementation Example 1>

As the particle-containing layer A, polyester resin I and polyester resin II were mixed at a mass ratio of 85:15 and melted by an extruder and supplied to the layer A of the stacking mold. As for the main layer B, polyester resin I was melted by an extruder and supplied to the layer B of the stacking mold. The two types of three-layer stacking polyester resins having a structure of layer A/layer B/layer A were co-extruded in a film form and cast onto a cooling drum at 35°C to produce a cold-cured unstretched film.

Next, after the unstretched film was preheated by a heating roll at 75°C, it was stretched 3.2 times in the longitudinal direction between rolls at 85°C using an infrared heater and a heating roll, and then a coating liquid containing a surface layer forming composition prepared by the formulation shown in Table 1 below was applied to the inner side line of the longitudinally stretched film. Then, the film end was gripped by a clip and introduced into a tenter and stretched at 95°C. ℃, stretched 4.5 times in the transverse direction, and heat treated at 225℃ for 10 seconds to produce a polyester film (sample) having a surface layer containing particles with a thickness of 0.030μm on the surface of a base polyester film with a thickness of 16.0μm (layer A/layer B/layer A=1.0μm/14.0μm/1.0μm) and a width of 1580mm.

<Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4>

As shown in Tables 1 and 2, except for changing the raw material of the base polyester film, the polyester film (sample) was prepared in the same manner as in Example 1.

<Comparison Example 5>

A polyester film (sample) was prepared in the same manner as in Example 1 except that a surface layer containing particles was not formed.

<Measurement method. Evaluation method>

The measurement methods and evaluation methods of the physical properties of the materials, base polyester and polyester film (samples) used in the embodiments and comparative examples are as follows.

(1) Thickness of polyester film (μm)

The thickness of the polyester film (sample) was measured using a micrometer.

(2) The thickness of each layer of the base polyester film (layer A and layer B), and the thickness of the surface layer containing particles

The thickness of each layer (layer A and layer B) of the base polyester film and the thickness of the surface layer containing particles were measured by observing the film cross section using a transmission electron microscope (TEM).

Specifically, first, a small piece of the membrane sample is embedded in a resin prepared by mixing a hardener and an accelerator in an epoxy resin, and then an ultramicrotome is used to make a slice with a thickness of 200 nm as a sample for observation.

The sample was observed using a transmission electron microscope (H-9000) manufactured by Hitachi High-technologies (Hitachi High-technologies Co., Ltd.). In the observed cross section, the interface between layer A and layer B, and the interface between the surface of the substrate polyester film and the surface layer containing particles were observed based on light and dark, almost parallel to the substrate polyester film.

The distance between the interface and the membrane surface was measured for 50 transmission electron microscope photos. Ten points with larger measured values were removed, and 10 points with smaller measured values were removed. The average of 30 points was used as the measured value. The thickness of each layer and the thickness of the surface layer containing particles were calculated based on the average value.

Among them, the accelerating voltage of the transmission electron microscope is 300kV, and the magnification is set in the range of 10,000 to 100,000 times according to the thickness of the surface layer.

(3) Average surface roughness of the membrane surface (Ra)

The average surface roughness (Ra) of the film surface on the opposite side to the particle-containing surface layer was determined as follows using a surface roughness tester (SE-3F) manufactured by Kosaka Laboratory Co., Ltd.

That is, a portion of the reference length L (2.5 mm) is extracted from the film cross-sectional curve obtained by measurement along its center line, the center line of the extracted portion is taken as the x-axis, the longitudinal magnification direction is taken as the y-axis, and when the roughness curve y = f (x) is used to represent, the value provided in the following formula is expressed in [μm].

The centerline average roughness is expressed by calculating 10 profile curves from the sample film surface and using the average centerline average roughness of the extracted parts calculated from these profile curves. In addition, the tip radius of the stylus is set to 2μm, the load is set to 30mg, and the critical value is set to 0.08mm.

(4) Maximum height of membrane surface (Rt)

The maximum height (Rt) of the film surface on the opposite side to the particle-containing surface layer is measured as follows.

For the extracted part of the cross-sectional curve obtained during the Ra measurement, when the extracted part is clamped by two straight lines parallel to its average line, the interval between the two straight lines is measured along the longitudinal magnification direction of the cross-sectional curve, and the value expressed in micrometers (μm) is taken as the maximum height (Rt) of the extracted part.

The maximum height is expressed by obtaining 10 profile curves from the sample film surface and using the average value of the maximum heights of the extracted parts obtained from these profile curves.

(5) Average particle size (μm)

The average particle size of particles in each layer is determined by observing more than 10 particles using a scanning electron microscope (SEM), measuring the particle diameters, and calculating the average value. At this time, in the case of non-spherical particles, the average value of the longest diameter and the shortest diameter is used as the diameter of each particle.

(6) Particle concentration of the base polyester film

In the polyester film (sample), a sample is cut from the layer where the particle concentration is to be measured, and a solvent that dissolves the polyester but not the particles is selected for dissolution. The particles are then centrifuged and separated from the solution. The mass ratio (ppm) of the particles relative to the total mass is measured as the particle concentration.

(7) Intrinsic viscosity

About 0.25 g of the frozen and crushed polyester film was dissolved in about 25 mL of a mixed solvent of phenol/1,1,2,2-tetrachloroethane (mass ratio 1/1) at a concentration of 1.00 g/dL at 120°C for 30 minutes, then cooled to 30°C. The falling seconds of the sample solution and the solvent alone were measured at 30°C using a fully automatic solution viscometer (manufactured by Sen-Tec, "DT553"), and the intrinsic viscosity was calculated using the following formula (1).

Intrinsic viscosity = ((1+4K _H η _sp ) ^0.5 -1)/(2K _H C)… Formula (1)

Here, η _sp =η/η ₀ -1, η is the falling seconds of the sample solution, η ₀ is the falling seconds of the solvent alone, C is the concentration of the sample solution (g/dL), and K _H is the Huggins constant. K _H is 0.33.

(8) Film fog

According to JIS K 7105:1981, the haze of the polyester film (sample) was measured using an integrating sphere turbidimeter NDH-20D manufactured by Nippon Denshoku Industries.

(9) Static friction coefficient and dynamic friction coefficient

According to American Society for Testing Material (ASTM)-D1894 (1999), two polyester films (samples) are prepared, and the static friction coefficient and dynamic friction coefficient of the combination of the upper surface and the lower surface of the polyester film (sample) are measured.

(10) Anti-static properties

The polyester film (sample) was fully humidified in a measurement environment of 23°C and 50% RH, and then a voltage of 100V was applied for 1 minute. The surface resistivity of the particle-containing surface layer of the substrate film was measured using a high resistance tester: HP4339B and a measuring electrode: HP16008B manufactured by Japan Hewlett-Packard. Based on the surface resistivity, the antistatic property was evaluated according to the following criteria.

○(good): Surface resistivity is 1×10 ¹² Ω/□ or less

△(usual): Surface resistivity greater than 1×10 ¹² Ω/□ and less than 2×10 ¹³ Ω/□

×(poor): Surface intrinsic resistance is greater than 2×10 ¹³ Ω/□

(11) Damage to the substrate film surface

In addition, a substrate film without a surface layer containing particles was prepared, and the surface of the substrate film was visually inspected and evaluated using the following criteria.

○ (Good): No scars were observed within the inspection range.

×(Deficient): Many scars were observed within the inspection area.

(12) Machinability of the particle-containing surface layer

An aluminum plate with a width of 10 mm and a length of 50 mm was brought into contact with the particle-containing surface layer of the polyester film (sample). A weight of 50 g was placed on the aluminum plate, and the aluminum plate was moved back and forth 10 times in a distance of 100 mm parallel to the width direction of the aluminum plate. The two ends of the particle-containing surface layer where the aluminum plate was moving were observed under a microscope and judged using the following criteria.

○ (good): Almost no cutting of the particle-containing surface layer was observed

× (Insufficient): The surface layer containing particles was cut and a lot of white powder was observed.

(13) Rollability

A polyester film (sample) was made into a roll with 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 wound roll was visually inspected and evaluated using the following criteria.

○ (good): The polyester film (sample) has no wrinkles and the roller end faces are completely aligned.

△(Normal): The roller ends are aligned, but the polyester film (sample) has small wrinkles.

× (Insufficient): The polyester film (sample) snakes during the roll winding process, or the polyester film (sample) has large wrinkles.

(14) Productivity

When continuously producing polyester films (samples) stretched 4.5 times or more in the transverse direction, the number of breaks (film ruptures) that occurred was determined using the following criteria.

○(Good): Less than once a day

△(General): More than once a day and less than three times a day

×(Insufficient): More than 3 times a day

(15) Evaluation of uneven thickness

Cut a polyester film (sample) from a 1000mm wide roll, overlap 5 sheets of the film, and measure the thickness at 20 equal positions of the 1000mm width using a micrometer. Divide the thickness at each position by the number of overlapping sheets, and take the thickness difference at adjacent positions as thickness unevenness, and judge using the following criteria.

○(Good): Thickness difference less than 0.50μm

△(General): Thickness difference is greater than 0.50μm and less than 1.00μm

×(Insufficient): Thickness difference is 1.00μm or more

According to the results of the embodiments and comparative examples, as well as the test results conducted by the inventors to date, it can be seen that by setting the inherent viscosity of the base polyester film to 0.65 dl/g or more, even if the stretching ratio, especially the stretching ratio in the width direction, is set to 4.5 times or more, it can be stretched without breaking, and the uneven thickness in the width direction of the film can be reduced, and the thickness of the film can be made uniform, preventing air accumulation when rolling into a roll, thereby reducing the occurrence of wrinkles.

In addition, it is known that by setting the average particle size of the particles contained in the A layer constituting the surface layer of the base polyester film to 0.030μm~0.200μm and the mass concentration thereof to 10ppm~7000ppm, and forming a particle-containing surface layer containing particles with an average particle size of 0.005μm~0.150μm, the flatness and transparency of the film can be further improved. Even so, the slipperiness of the film can be improved, so that it can not only be rolled into a roll, but also reduce damage.

Claims (7)

A polyester film for dry film anticorrosive agent, which has a surface layer containing particles on at least one side of a base polyester film with an inherent viscosity of 0.65 dl/g or more. The polyester film for dry film anticorrosive agent is characterized in that: the base polyester film is a single layer composed of a polyester layer (referred to as "A layer") or a multi-layer film having the A layer on the surface, the polyester layer contains particles with an average particle size of 0.030μm to 0.200μm at a mass ratio of 2250ppm to 7000ppm, and does not contain particles with a particle size of 0.300μm or more, and the particle-containing surface layer contains particles with an average particle size of 0.005μm to 0.150μm. The polyester film for dry film anticorrosive as described in item 1 of the patent application, wherein the particle-containing surface layer further comprises one or both of an antistatic agent and wax. The polyester film for dry film anticorrosive agent as described in item 1 or 2 of the patent application scope, wherein the base polyester film has the A layer only on one side, and has the particle-containing surface layer on the opposite side of the A layer. As described in item 1 or 2 of the patent application scope, the polyester film for dry film anticorrosive agent, wherein the base polyester film comprises three layers, and the two sides thereof are A layers. A polyester film for dry film anticorrosive as described in item 1 or 2 of the patent application, wherein the average particle size of the particles contained in the particle-containing surface layer is larger than the average particle size of the particles contained in the A layer. A method for producing a polyester film for a dry film anti-corrosion agent, wherein the polyester film for a dry film anti-corrosion agent is produced as described in any one of items 1 to 5 of the patent application scope, and the method for producing a polyester film for a dry film anti-corrosion agent is characterized in that the base polyester film is stretched in the width direction at a stretching ratio of 4.0 times or more. A photosensitive laminate having a photoresist layer laminated on at least one side of a polyester film for dry film resist as described in any one of items 1 to 5 of the patent application scope.