Polyester film and method for producing the same

Abstract

The polyester film contains particles with an average particle size of 0.03 to 0.80 μm, the antimony element in the film is 3 ppm or less, and the total content of titanium element, phosphorus element, and magnesium element in the film is 5 to 100 ppm. It is possible to provide a polyester film that can meet the needs of applications that extremely dislike the presence of foreign substances in the film.

Description

Technical Field

[0001] The present invention relates to a polyester film and a method for producing the same.

Background Art

[0002] Conventionally, polyester films have excellent mechanical properties and chemical resistance, and are widely used as members for various applications such as magnetic tapes, ferromagnetic thin film tapes, photographs, packaging, electronic components, electrical insulation, and metal laminates.

[0003] Among the uses of polyester films, there are applications that extremely dislike the presence of foreign substances in the film. For example, dry film resist formation is one such example. Dry film resist is widely used as a resist for forming wiring patterns on electronic circuit boards, and is generally a three-layer structure 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").

[0004] As a method for manufacturing an electronic circuit board using the above dry film resist, for example, first, the protective film is peeled off from the dry film resist to expose the photoresist layer, and the photoresist layer is overlapped on the copper layer surface of an epoxy resin board having a copper layer laminated on the surface, and the dry film resist is attached. Then, the support film is overlapped on a glass plate on which a circuit is printed, and the dry film resist is adhered, and light is irradiated from the glass plate side. This light passes through the transparent portions of the circuit printed on the glass plate and within the support film layer, and then irradiates the photoresist layer. The portions of the photoresist layer irradiated with light are cured by the light. Next, after removing the glass plate and the support film, the uncured portions of the photoresist layer are removed, and etching is performed using an acid or the like. At this time, the copper layer at the corresponding locations is exposed due to the removal of the uncured portions of the photoresist layer, and the exposed copper layer 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 board can be manufactured.

[0005] Regarding the polyester film used for forming a dry film resist, for example, in Patent Document 1, there is disclosed a biaxially oriented laminated polyester film containing particles with an average particle diameter of 0.01 to 3.0 μm in at least the outermost layer on one side, where the center line average roughness Ra of the outermost layer is 0.005 μm or more and the maximum height Rt is less than 1.5 μm, and the haze value is 1.5% or less.

[0006] Patent Document 2 discloses a laminated polyester film for a dry film resist that has excellent winding properties, can more reliably prevent the occurrence of circuit defects, and can support high resolution. It is composed of at least two polyester layers, and the number of metal-containing aggregates with a major axis of 10 μm or more is 5 pieces / 10 cm 2 or less, and at least one of its outermost layers contains particles with an average particle diameter of 0.01 to 3.0 μm, and the center line average roughness Ra of the surface is 0.002 to 0.030 μm and the maximum height Rt is 0.05 to 1.0 μm.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] In a dry film resist, since light is irradiated through a support film onto a photoresist layer for exposure, if aggregates (foreign substances) are present in the support film, this may cause inhibition of resist curing and result in circuit defects. For example, in order to improve the handling properties and winding characteristics of the support film, it is common to contain particles in the film and form fine protrusions on the surface. However, these particles may aggregate to become foreign substances, and also, metals contained in the polymerization catalyst of the resin constituting the film may aggregate to become foreign substances, which may cause inhibition of resist curing.

[0009] In recent years, due to the miniaturization of electronic devices, the circuits formed have become extremely complex, the line width of the resist has decreased from 5 μm to 2 μm, and further miniaturization is progressing. Therefore, for dry film resists, higher reproducibility of image formation and further higher resolution are required, and the size of the problematic aggregates (foreign substances) has also become smaller and smaller.

[0010] Therefore, the present invention provides a polyester film capable of coping with applications that extremely dislike the presence of foreign substances in the film, such as for forming dry film resists and manufacturing ceramic green sheets.

Means for Solving the Problems

[0011] In view of the above circumstances, the present inventor has conducted intensive studies and as a result, has found that the above problems can be easily solved by using a film having a specific configuration, and has completed the present invention. That is, the present invention provides the following [1] to

[18] .

[0012] [1] A polyester film containing particles with an average particle size of 0.03 to 0.80 μm, with the antimony element in the film being 3 ppm or less and the total content of titanium, phosphorus, and magnesium elements in the film being 5 to 100 ppm. [2] The number of protrusions with a major axis of 1 μm or more and less than 3 μm in the film is 350 pieces / cm 2 The polyester film according to [1] above, wherein the number is 350 pieces / cm or less. [3] The number of protrusions with a maximum peak height (Sp) protruding from the film surface of 0.3 μm or more is 2.7 pieces / cm 2 The polyester film according to [1] or [2] above, wherein the number is 2.7 pieces / cm or less. [4] The polyester film according to any one of [1] to [3] above, wherein the film is a multilayer film comprising a polyester layer B and a polyester layer A on at least one surface thereof. [5] The polyester film according to any one of [1] to [4] above, wherein the content of titanium element in the polyester film is 1 ppm or more and 30 ppm or less. [6] The polyester film according to [1] above, wherein the content of phosphorus element in the polyester film is 5 ppm or more and 35 ppm or less. [7] The polyester film according to any one of [1] to [5] above, wherein the content of magnesium element in the polyester film is 5 ppm or more and 35 ppm or less. [8] The polyester film according to any one of [4] to [7] above, wherein all polyester layers constituting the polyester film contain titanium element. [9] The polyester film according to any one of [4] to [8] above, wherein the polyester layer A contains particles with 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.

[10] The polyester film according to any one of [4] to [9] above, wherein the particle content in the polyester layer A is in the range of 10 to 6000 ppm.

[11] The polyester film according to any one of [4] to

[10] above, containing two types of particles having different average particle diameters in the polyester layer A.

[12] The polyester film according to any one of [4] to

[11] above, containing particle Y having an average particle diameter in the range of 0.30 to 0.80 μm and a maximum particle diameter of 1.0 μm or less in the polyester layer A.

[13] The polyester film according to any one of [1] to

[12] above, having another resin layer on at least one surface of the polyester film.

[14] A manufacturing method of the polyester film according to any one of [1] to

[13] above, including a manufacturing process 1 of filtering a melt of polyester resin chips containing a titanium compound, which has been pre-masterbatchized, with a filter medium containing a powder sintered body and a filter medium containing a fibrous sintered body having a filtration accuracy of 5 μm or less, and a manufacturing process 2 of manufacturing a polyester film using the polyester resin melt obtained in the manufacturing process 1.

[15] The polyester film according to any one of [1] to

[13] above, which is for manufacturing a dry film resist.

[16] The polyester film according to any one of [1] to

[13] above, which is for manufacturing a ceramic green sheet.

[17] The polyester film according to any one of [1] to

[13] above, which is for forming an interlayer insulating layer.

[18] The polyester film according to any one of [1] to

[13] above, which is for optical use.

Advantages of the Invention

[0013] According to the present invention, it is possible to provide a polyester film capable of coping with applications that extremely dislike the presence of foreign substances in the film, such as for forming a dry film resist and for manufacturing a ceramic green sheet. More specifically, the polyester film of the present invention has the advantage that the generation of aggregates (foreign substances) such as particles and metals is reduced while maintaining the flatness, handleability, and winding characteristics of the film.

Embodiments for Carrying Out the Invention

[0014] Next, the present invention will be described based on exemplary embodiments. However, the present invention is not limited to the embodiments described below.

[0015] <Polyester film> The polyester film of the present invention contains particles having an average particle diameter of 0.03 to 0.80 μm in the film, the antimony element in the film is 3 ppm or less, and the total content of titanium element, phosphorus element, and magnesium element in the film is 5 to 100 ppm. Also, the number of foreign matters having a major axis of 1 μm or more and less than 3 μm in the film is preferably 350 pieces / cm 2 or less. Furthermore, the number of protrusions having a maximum peak height (Sp) protruding from the film surface of 0.3 μm or more is preferably 2.7 pieces / cm 2 or less.

[0016] The content of titanium element in the film is preferably 1 ppm or more and 30 ppm or less. Also, the content of phosphorus element in the polyester film is preferably 5 ppm or more and 35 ppm or less, and the content of magnesium element in the polyester film is preferably 5 ppm or more and 35 ppm or less.

[0017] Also, the polyester film of the present invention is preferably a multilayer film including a polyester layer B and a polyester layer A on at least one surface thereof. In the polyester layer A, it is preferable to contain particles having an average particle diameter in the range of 0.03 to 0.80 μm and a maximum particle diameter of 2.0 μm or less, more preferably 1.0 μm or less. According to the above aspect, while maintaining the flatness, handleability, and winding characteristics of the film, the generation of aggregates (foreign matters) due to particles can be reduced. Also, the polyester film of the present invention contains a titanium element. More specifically, for example, by using a polyester raw material using a titanium compound as a polymerization catalyst, the generation of metal aggregates (foreign matters) derived from the polymerization catalyst can be reduced. When the polyester film of the present invention is multilayered, it is preferable that all polyester layers contain titanium elements.

[0018] <Polyester> The polyester, which is the raw material of polyester layer A and polyester layer B, is not particularly limited as long as it is a polyester obtained mainly from aromatic dicarboxylic acid or its ester and glycol as starting materials. Among them, it is preferable that the polyester has ethylene terephthalate units or ethylene-2,6-naphthalate units in more than 60% of the repeating structural units. In addition, the polyester may contain a third component other than ethylene terephthalate units and ethylene-2,6-naphthalate units as a copolymer component or a mixed component. For example, a resin compatible with a polyester resin such as polycarbonate may be mixed.

[0019] Examples of the aromatic dicarboxylic acid component include terephthalic acid, dimethyl terephthalate, 2,6-naphthalenedicarboxylic acid, isophthalic acid, phthalic acid, adipic acid, sebacic acid, etc. In particular, terephthalic acid or dimethyl terephthalate is preferable.

[0020] Examples of the glycol component include one or more of ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, etc. In particular, ethylene glycol is preferable.

[0021] When the polyester is a copolyester, examples of its dicarboxylic acid component include one or more of isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, sebacic acid, etc., and examples of its glycol component include one or more of ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, etc.

[0022] The intrinsic viscosity of the polyester is not particularly limited, but from the viewpoints of film-forming properties and particle dispersibility in the polyester, it is preferably 0.45 to 1.0 dl / g, more preferably 0.50 to 0.90 dl / g, and even more preferably 0.60 to 0.80 dl / g.

[0023] In the present invention, it is preferable to use a polyester containing a titanium compound as a polymerization catalyst. The titanium compound has high catalytic activity and can perform polymerization in a small amount. By using a polyester polymerized with the titanium compound as a raw material, the amount of metal remaining in the film is reduced, so there is little risk of becoming aggregates (foreign substances).

[0024] (Other compounds) Examples of additives other than the titanium compound include phosphorus compounds, manganese compounds, aluminum compounds, magnesium compounds, calcium compounds, and the like.

[0025] (Phosphorus compound) The content of the phosphorus compound in the film is preferably 5 ppm or more and 35 ppm or less, more preferably 5 ppm or more and 25 ppm or less, and particularly preferably 5 ppm or more and 15 ppm or less in terms of the amount of phosphorus element. By using the phosphorus compound in combination, an effect of improving the thermal stability of the polyester resin can be expected.

[0026] (Magnesium compound) The content of the magnesium compound of the phosphorus compound in the film is preferably 5 ppm or more and 35 ppm or less, more preferably 5 ppm or more and 25 ppm or less, and particularly preferably 5 ppm or more and 15 ppm or less in terms of the amount of magnesium element. By using the magnesium compound in combination, an effect of improving the adhesion can be imparted when electrostatically adhering the polyester resin sheet to the casting drum.

[0027] Furthermore, on the premise of satisfying the above range, as an additional requirement, it is preferable to satisfy the following formula. (Titanium element content + magnesium element content) / phosphorus element content ≥ 1.3 The titanium compound can be expected to have an effect of suppressing the by-production of foreign matters with a size of 1 μm in the polymerization reaction of the polyester resin. On the other hand, the magnesium compound contributes to improving the adhesion when melting the polyester resin and adhering it to the casting drum, and thus contributes to forming a highly smooth sheet surface. By satisfying the above formula, in particular, it is possible to form a film having a high-smooth surface while reducing minute foreign matters with a size of 1 μm.

[0028] In the present invention, in particular, from the viewpoint of reducing minute aggregates (foreign matters) in the film having a major axis of 1 μm or more and less than 3 μm, the content of the compound derived from the metal element is preferably as small as possible. These compounds derived from metal elements tend to be recognized as minute foreign matters in the film. Therefore, the total content (Ti + P + Mg) of the titanium compound, phosphorus compound, and magnesium compound in the polyester film needs to be 5 ppm or more and 100 ppm or less in terms of elemental conversion. Preferably, it is 5 ppm or more and 90 ppm or less, more preferably 5 ppm or more and 75 ppm or less, particularly preferably 10 ppm or more and 50 ppm or less, and most preferably 15 ppm or more and 40 ppm or less.

[0029] (Method for producing masterbatch) The polyester film of the present invention can be produced by first preparing a masterbatch containing a polyester resin and particles, and using this to produce the film. The method for producing the masterbatch in the present invention may have a step of blending and melt-kneading the above polyester resin and particles, or particles may be added during the polymerization of the above polyester resin. First, the polyester, the particles, and, if necessary, the other components which are optional raw material components are blended in various forms such as bulk, pellet, chip, etc. to have a predetermined blending ratio, and then, after preliminary mixing if necessary, they are put into a melt kneader and heated to a temperature equal to or higher than the melting point of the polyester resin for melt kneading.

[0030] The embodiment of the melt kneaded product is not particularly limited as long as the effects of the present invention are not impaired. It is preferable to directly add a diluting polyester resin in the molten state, once extrude it into strands and then cut it into granular forms such as pellets and chips. In the above melt kneading step, the preliminary mixing is not particularly limited as long as the effects of the present invention are not impaired, and examples include dry blending using a ribbon blender, a Henschel mixer, a V blender, etc. Further, the melt kneader is not particularly limited as long as the effects of the present invention are not impaired, and examples include a melt kneader equipped with a heating mechanism such as a Banbury mixer, a mixing roll, a single-screw or twin-screw extruder, and a kneader. In addition, the melt kneader in the above step may be equipped with a filter having an opening in the range of 100 μm or less, preferably 50 μm or less, and more preferably 30 μm or less inside the apparatus.

[0031] The content of the 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 even more preferably 90% by mass or more, respectively. When the amount of the polyester is equal to or more than the above lower limit value, the flexibility, strength, etc. of the polyester film can be ensured.

[0032] <Polyester layer A> The polyester layer A is preferably a layer containing particles (hereinafter sometimes referred to as "particle P") 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, the polyester layer A is provided on at least one surface of the polyester layer B described later, and constitutes the polyester film in the present invention, which is a multilayer film. When the polyester layer A contains the particles P, good handleability can be obtained, and a large number of scratches do not occur on the film surface during the film-forming process of the polyester film. As described above, since light is irradiated and exposed to the resist layer through the support film, if there are foreign matters or scratches on the support film of the dry film resist, that part will not be exposed and circuit defects will occur. Therefore, when this polyester film is used as the support film of the dry film resist, it is particularly preferable that the A layer forming the polyester film surface contains particles. In addition, by using the particles P, it becomes difficult for the particles to cause inhibition of resist curing as aggregates (foreign matters).

[0033] The average particle diameter of the particles P contained in the polyester layer A is preferably in the range of 0.03 μm to 0.80 μm. If the average particle diameter of the particles P is 0.80 μm or less, the transparency of the film is not impaired. On the other hand, if the average particle diameter of the particles is 0.03 μm or more, the film surface can be moderately roughened, not only improving the handleability, but also expecting an effect of preventing scratches on the film surface in the film-forming process of the polyester film. From such a viewpoint, the average particle diameter of the particles contained in the polyester layer A is preferably 0.10 μm to 0.75 μm, more preferably in the range of 0.15 μm to 0.70 μm, and particularly preferably in the range of 0.30 μm to 0.60 μm.

[0034] The average particle diameter of the particles P in the polyester layer A is determined as the average value by measuring the diameters of 10 or more particles with a scanning electron microscope. In that case, 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.

[0035] Furthermore, it is preferable that the maximum particle size of the particles contained in the polyester layer A is 2.0 μm or less. If it is within this range, it is possible to suppress the inhibition of resist curing caused by the particles becoming aggregates (foreign substances). From such a viewpoint, the maximum particle size of the particles contained in the polyester layer (A) is more preferably 1.0 μm or less, even more preferably 0.80 μm or less, and among them, 0.60 μm or less is more preferable. In addition, the maximum particle size of the particles refers to the particle size of the primary particles constituting them when the particles exist as aggregates.

[0036] Furthermore, it is preferable that the polyester layer A contains the particles P having an average particle size of 0.03 μm to 0.80 μm as described above at a mass ratio (also referred to as "concentration") of 10 to 6000 ppm. In the polyester layer A, if the content (particle concentration) of the particles P having an average particle size of 0.03 μm to 0.80 μm is 6000 ppm or less, the transparency of the film can be further enhanced. On the other hand, if the content (particle concentration) of the particles P having an average particle size of 0.03 μm to 0.80 μm is 10 ppm or more, the film surface can be moderately roughened, not only improving the handleability, but also expecting an effect of preventing scratches on the film surface in the film forming process of the polyester film. From such a viewpoint, it is more preferable that the polyester layer A contains the particles P having an average particle size of 0.03 μm to 0.80 μm at a mass ratio of 100 ppm to 5000 ppm, and among them, it is even more preferable to contain them at a mass ratio of 500 ppm to 4500 ppm, and among them, it is particularly preferable to contain them at a mass ratio of 1000 ppm to 4000 ppm.

[0037] The particles P contained in the polyester layer A are not particularly limited as long as they have an average particle size of 0.03 to 0.80 μm, and examples thereof include inorganic particles such as calcium carbonate, calcium phosphate, silica, kaolin, talc, alumina, barium sulfate, calcium fluoride, lithium fluoride, zeolite, and molybdenum sulfide, and organic particles such as ion exchange resins, crosslinked polymers, and calcium oxalate. From the viewpoint of effectively improving the film surface roughness and from the viewpoint of production costs, inorganic particles are preferred, and alumina and silica are more preferred. On the other hand, from the viewpoint of efficiently imparting slipperiness and air escape properties to the film surface, organic particles are preferred, and crosslinked polymers such as crosslinked polystyrene particles and crosslinked acrylic particles are more preferred.

[0038] The polyester layer A may contain one type of particle P, two or more types of particles, or the same type of particles with different particle sizes or shapes may be used at the same time. The shape of the particles is not particularly limited, and may be any of spherical, blocky, rod-like, flat, and other shapes. In order to effectively impart slipperiness to the surface, the polyester layer A preferably contains at least two kinds of particles having different particle sizes. The two kinds of particles are referred to as particles X and Y and will be described below. From the viewpoint of suppressing the occurrence of scratches on the film surface during processing, it is preferable to use particles X in combination with particles Y having an average particle size larger than that of particles X.

[0039] The average particle size of the particles X is preferably in the range of 0.03 μm to 0.20 μm within the particle size range of the particles P, which is 0.03 μm to 0.80 μm, more preferably in the range of 0.04 μm to 0.15 μm, and particularly preferably in the range of 0.05 μm to 0.10 μm. If the average particle size of the particles X is 0.20 μm or less, they are less likely to form aggregates (foreign matter), and if the average particle size of the particles is 0.03 μm or more, they can contribute to improving the slipperiness of the film surface.

[0040] The mass ratio of particle X in the polyester layer A is preferably in the range of 100 to 5000 ppm, more preferably in the range of 500 ppm to 4000 ppm, and particularly preferably in the range of 1000 ppm to 3000 ppm, within the range of 10 to 6000 ppm which is the content ratio of particle P. If the mass ratio of particle X in the polyester layer A is 100 ppm or more, it can contribute to improving the slipperiness of the film surface, and if the mass ratio of particle X is 5000 ppm or less, the light transmittance of the polyester film can be maintained.

[0041] The average particle diameter of particle Y is preferably in the range of 0.30 μm to 0.80 μm, more preferably in the range of 0.35 μm to 0.70 μm, and particularly preferably in the range of 0.40 μm to 0.60 μm, within the range of 0.03 μm to 0.80 μm which is the particle diameter range of particle P. If the average particle diameter of particle Y is 0.80 μm or less, it is less likely to cause inhibition of resist curing, and if the average particle diameter of the particle is 0.30 μm or more, the slipperiness of the film surface and the winding property when the film is made into a wound body (roll body) are improved.

[0042] The mass ratio of particle Y in the polyester layer A is preferably in the range of 10 to 3000 ppm, more preferably in the range of 100 ppm to 2500 ppm, and particularly preferably in the range of 200 ppm to 2000 ppm, within the range of 10 to 6000 ppm which is the content ratio of particle P. If the mass ratio of particle Y in the polyester layer A is 10 ppm or more, the slipperiness and air permeability of the film surface can be imparted, and if the mass ratio of particle Y is 3000 ppm or less, the light transmittance of the polyester film can be maintained.

[0043] The average particle size of particle Y is preferably larger than that of particle X and the maximum particle size is 1.0 μm or less. Also, particle Y preferably has a narrow particle size distribution width. Specifically, the value obtained by dividing the average particle size of particle Y by the maximum particle size of particle Y (average particle size of particle Y / maximum particle size of particle Y) is preferably 0.4 or more, more 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 particle Y by the maximum particle size of particle Y (average particle size of particle Y / maximum particle size of particle Y) is 0.4 or more, since the maximum particle size of the particles is below a certain value, it is possible to suppress the particles from causing inhibition of resist curing as aggregates (foreign substances). Moreover, since relatively large average particle size particle Y is contained in the polyester layer A, the surface of the film can be roughened without increasing the mass ratio (concentration) of the particles in the polyester layer A. Therefore, not only is the handleability improved without degrading the transparency of the film, but also the film surface is prevented from being scratched during the film formation process of the polyester film, and the winding property is excellent when the film is formed into a wound body (roll body).

[0044] As an example of a preferred embodiment when the polyester layer A contains particle X and particle Y, the average particle size of particle X is in the range of 0.03 μm to 0.19 μm, the average particle size of particle Y is in the range of 0.20 μm to 0.80 μm, the mass ratio of particle X in the polyester layer A is in the range of 100 to 5000 ppm, and the mass ratio of particle Y is in the range of 10 to 3000 ppm. In the above embodiment, the film surface has excellent slipperiness, can prevent the occurrence of scratches, and has excellent winding property when the film is formed into a wound body (roll body).

[0045] Examples of particle X and particle Y include inorganic particles, organic particles, etc. as described above. From the viewpoint of effectively improving dispersibility and film surface roughness, inorganic particles are preferred as particle X with a relatively small average particle size, and alumina is more preferred. On one hand, as the particles Y with relatively large average particle size, organic particles are preferable from the viewpoints of difficulty in aggregation, ease of adjusting the particle size distribution, and prevention of scratches on the film surface. Among them, crosslinked polymers such as crosslinked polystyrene-based particles and crosslinked acrylic-based particles, and ion exchange resins are more preferable. Also, from the viewpoints of manufacturing cost and handleability, inorganic particles are preferable, and among them, silica particles are more preferable.

[0046] As the polyester constituting the polyester layer A, the aforementioned polyester can be used. However, from the viewpoint of suppressing the generation of aggregates (foreign matters) in the polyester film, it is preferable to use a polyester containing a titanium compound as a polymerization catalyst. The polymerization catalyst composed of a titanium compound has high catalytic activity and can be polymerized in a small amount. By using a polyester polymerized with a titanium compound as a catalyst as a raw material, the amount of metal remaining in the film is small, so the risk of becoming aggregates (foreign matters) is small. From the viewpoint of reducing aggregates (foreign matters), it is further preferable that the film does not substantially contain an antimony compound. "Does not substantially contain" means that it is not intentionally contained in the film, and the content is 3 ppm or less, preferably 2 ppm or less, more preferably 1 ppm or less, and among them, particularly 0 ppm.

[0047] From the viewpoints of transparency and the like, the thickness of the polyester layer A is preferably 0.1 to 20.0 μm, more preferably 0.3 μm to 10.0 μm, and still more preferably 0.5 μm to 5.0 μm.

[0048] <Polyester layer B> The polyester film of the present invention preferably includes a polyester layer B and the polyester layer A on at least one surface thereof. The polyester layer B preferably substantially does not contain particles or contains particles at a lower concentration than at least the polyester layer (A) in order to enhance the handleability and winding characteristics of the film while maintaining the transparency of the film. The above-mentioned "substantially free of" means not intentionally containing, specifically referring to the content (particle concentration) of particles being 200 ppm or less, more preferably 150 ppm or less.

[0049] When the polyester layer B contains particles, in order to suppress costs and enhance transparency, the average particle size of the particles contained in the polyester layer B is preferably smaller than the average particle size of the particles contained in the polyester layer A, preferably in the range of 0.010 μm to 0.200 μm, more preferably in the range of 0.012 μm to 0.100 μm, and particularly preferably in the range of 0.015 μm to 0.080 μm. Also, when the polyester layer (B) contains particles, from the viewpoints of maintaining light transmittance during exposure and eliminating circuit defects after exposure, the polyester layer B, similar to the polyester layer (A), preferably has a maximum particle size of the particles of 1.0 μm or less.

[0050] Furthermore, the particle concentration in the polyester layer B is preferably at least lower than the particle concentration in the polyester layer A as described above in order to enhance transparency. Specifically, the mass ratio is preferably in the range of 0 to 2500 ppm, more preferably 2000 ppm or less, still more preferably 1000 ppm or less, and most preferably 100 ppm or less.

[0051] Also, the types, shapes, etc. of the particles contained in the polyester layer B are the same as those of the particles in the A layer.

[0052] As the polyester constituting the polyester layer B, the aforementioned polyester can be used. However, from the viewpoint of suppressing the generation of aggregates (foreign substances) in the film, it is preferable to use a polyester containing a titanium compound as a polymerization catalyst. That is, the polyester layer B preferably contains titanium element.

[0053] The thickness of the polyester layer B is preferably adjusted so that the thickness of the polyester layer A with respect to the thickness of the polyester layer B is 0.1 to 40.0% from the viewpoints of enhancing transparency and improving the handleability and winding characteristics of the film. More preferably, it is adjusted to be 1.0% to 20.0%, and even more preferably, it is adjusted to be 3.0% to 10.0%.

[0054] <Polyester layer C> When the polyester film of the present invention includes a polyester layer other than the polyester layer A and the polyester layer B (hereinafter sometimes referred to as "polyester layer C"), the polyester layer C is preferably made of the above-mentioned polyester and contains particles at a concentration lower than at least that of the polyester layer A. Alternatively, it may contain particles in the same manner as the polyester layer A and have a different thickness from the polyester layer A. The type and shape of the particles in the polyester layer C are the same as those in the polyester layer A.

[0055] The thickness of the polyester layer C is preferably 1 to 300% of the thickness of the polyester layer A from the viewpoints of enhancing transparency and suppressing costs. More preferably, it is 10 to 200%, and even more preferably, it is 20 to 150%.

[0056] <Polyester film> The polyester film of the present invention is a film including the polyester layer B and the polyester layer A on at least one surface thereof. The polyester layer A may be provided on both surfaces of the polyester layer B, or the polyester layer A may be provided on one surface of the polyester layer B and the polyester layer C may be provided on the other surface. Specific configurations include, for example, polyester layer A / polyester layer B, polyester layer A / polyester layer B / polyester layer A, etc. Furthermore, polyester layer A / polyester layer B / polyester layer C, polyester layer A / polyester layer B / polyester layer C / polyester layer A, etc. can also be exemplified. However, it is not limited to these.

[0057] The polyester film of the present invention may have an intrinsic viscosity of 0.65 dl / g or more. When the intrinsic viscosity is 0.65 dl / g or more, as will be described later, even if the draw ratio, especially the draw ratio in the width direction (lateral direction), is increased to 4.0 times or more, it can be drawn without breakage. Therefore, in particular, the thickness unevenness of the film in the width direction can be reduced, and the accumulation of air can be suppressed when winding it into a roll shape, thereby reducing the occurrence of wrinkles. Also, as an accompanying effect, when melt-extruding each polyester layer, the shear stress applied to the raw material of each polyester layer increases, the dispersibility of the particles contained in the raw material is improved, and the generation of aggregates (foreign matters) due to the particles is suppressed. From such a viewpoint, the intrinsic viscosity of the polyester film is preferably 0.65 dl / g or more, more preferably 0.65 dl / g or more and 0.90 dl / g or less, and even more preferably 0.66 dl / g or more and 0.80 dl / g or less. The intrinsic viscosity of the polyester film can be adjusted by appropriately changing the polymerization conditions of the polyester as the raw material. For example, by increasing the polymerization time or adopting solid-phase polymerization to increase the molecular weight, the intrinsic viscosity can be increased. Note that the above-mentioned intrinsic viscosity means the intrinsic viscosity of the entire polyester film layer.

[0058] The polyester film of the present invention may be an unstretched film (sheet) or a stretched film. Among them, a stretched film is preferably used, and a biaxially stretched film is more preferably used. When the polyester film of the present invention is a biaxially stretched film, it may be a sequential secondary stretched film or a simultaneous biaxially stretched film.

[0059] From the viewpoints of handleability and economy, the thickness of the polyester film is preferably 4 μm to 50 μm, more preferably in the range of 9 μm to 38 μm, and even more preferably 12 μm to 25 μm.

[0060] In the polyester film of the present invention, the number of foreign matters or aggregates having a major axis of 1 μm or more and less than 3 μm is preferably 350 pieces / cm 2 or less. More preferably, it is 300 pieces / cm 2 or less, even more preferably 200 pieces / cm 2 or less, and particularly preferably 100 pieces / cm 2 or less. According to the study by the present inventors, aggregates (foreign matters) are formed by the precipitation and aggregation of a catalyst added during the production of polyester and remaining in the film, or by the aggregation of particles added to the polyester layer. In addition, when particles having a large particle size (for example, a particle size exceeding 2 μm) are contained in the particles added to the polyester layer, they are counted as aggregates (foreign matters), and among such aggregates (foreign matters), aggregates (foreign matters) having a major axis of 2 μm or more cause inhibition of resist curing, leading to circuit defects in the manufactured electronic circuit board. For example, in the production of polyester, when antimony trioxide, which is an antimony compound, is used as a polymerization catalyst, residual antimony precipitates and aggregates, forming aggregates (foreign matters) containing antimony in the polyester. For this reason, aggregates (foreign matters) exist in the film using polyester and are expanded in the film plane by biaxial stretching. Therefore, the number of aggregates (foreign matters) leading to circuit defects, that is, the number of aggregates having a major axis of 1 μm or more and less than 3 μm, is 350 pieces / cm 2It is necessary to be as follows.

[0061] Here, the width of the circuit formed by the dry film resist is, for example, 5 μm or less, and high definition is progressing, and in some cases, 2 μm or less is required. The irradiation light for curing the resist of 2 μm or less passes through the polyester film with a width of, for example, 2 μm or less. Therefore, even in the case of aggregates (foreign matters) having a major axis of less than 2 μm, there is a concern that the risk of light shielding increases with respect to the light passing through the polyester film with a width of 2 μm or less. Therefore, in order to suppress the occurrence of circuit defects caused by aggregates (foreign matters) of 1 μm or more and less than 3 μm, the situation requires the management of the number of aggregates (foreign matters). Therefore, in the present invention, the number of aggregates (foreign matters) in the film having a major axis of 1 μm or more and less than 3 μm is 350 pieces / cm 2 By being less than or equal to the above, it has been found that there is an inhibitory effect on the occurrence of circuit defects, and the present invention has been completed.

[0062] Note that the above aggregates (foreign matters) can be observed using an optical microscope or the like, and the maximum diameter of the aggregates (foreign matters) can be measured. Therefore, the number of aggregates (foreign matters) in the film having a major axis of 1 μm or more and less than 3 μm can be determined by an optical microscope or the like. In the present invention, the "aggregate (foreign matter)" does not necessarily mean that some substances are aggregated. That is, as long as the substance corresponding to the above major axis is confirmed in the polyester film, it shall be regarded as corresponding regardless of aggregation.

[0063] Examples of the above aggregates (foreign matters) include those in which particles are aggregated, particles having a large particle size, aggregates of metal compounds used as catalysts, or reduced metals. According to the study by the present inventor, among the metal elements contained in the polymerization catalyst of polyester, antimony, titanium, and germanium, and among them, antimony has a higher light shielding property than other metals. Therefore, it has been found that if these metal elements are contained above a specific content, it will affect the performance of the high-definition dry film resist.

[0064] In the polyester film of the present invention, the content of titanium element is preferably 1 ppm or more and 30 ppm or less. When the content of titanium element is 30 ppm or less, in the polyester film, the number of titanium element-containing aggregates (foreign matters) can be reduced, the ratio of the transmitted light blocked by the titanium-containing aggregates (foreign matters) can be lowered, and the reduction of resolution can be suppressed to reduce circuit defects and the like generated in the electronic circuit board. Also, when the content of titanium element is 1 ppm or more, it is appropriate as the catalyst amount of polyester, and the production efficiency of polyester can be maintained. From the above viewpoints, the content of titanium element in the polyester film is more preferably 2 ppm or more and 25 ppm or less, and even more preferably 5 ppm or more and 20 ppm or less.

[0065] The content of titanium element in the polyester film can be quantified by fluorescence X-ray analysis method or the like.

[0066] (Other resin layer) The polyester film may have a structure in which another resin layer is laminated on at least one surface of the film in order to improve the handling property and winding property of the film. When the polyester film is composed of two layers of polyester layer A and polyester layer B, it is preferable to form the other resin layer (hereinafter sometimes simply referred to as "resin layer") on the side opposite to the polyester layer A, that is, on the polyester layer B side. On the other hand, when the polyester film is composed of three layers of polyester layer A, polyester layer B and polyester layer C, the other resin layer is preferably on the polyester layer A side. Specifically, it is preferably configured as other resin layer / polyester layer A / polyester layer B / polyester layer C.

[0067] The other resin layer preferably contains particles having an average particle diameter of 0.005 to 0.150 μm. If the average particle size of the particles contained in the other resin layer is 0.005 μm or more, the slipperiness and winding property of the film can be preferably maintained. If the average particle size is 0.150 μm or less, it becomes difficult for the particles to fall off from the resin layer, and it also becomes difficult for the resin layer to be scraped off. From such a viewpoint, the other resin layer preferably has an average particle size of 0.010 μm to 0.120 μm, and among them, preferably contains particles of 0.030 μm to 0.100 μm.

[0068] In addition, if the average particle size of the particles contained in the other resin layer is within the above range, the other resin layer may contain particles having a particle size of less than 0.005 μm or may contain particles having a particle size larger than 0.150 μm.

[0069] The average particle size of the particles in the other resin layer can be determined as an average value by measuring the diameters of 10 or more particles with a scanning electron microscope. In that case, 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.

[0070] The particle concentration in the other resin layer is preferably 1 to 10% by mass. If the particle concentration in the resin layer is 1% by mass or more, lubricity and winding improvement effects can be imparted. On the other hand, if it is 10% by mass or less, the particles are less likely to aggregate, the scraping of the resin layer due to particle detachment can be reduced, the light transmission of the film for a dry film resist substrate is less likely to be inhibited, and circuit defects are less likely to occur. From such a viewpoint, the particle concentration in the other resin layer is more preferably 2 to 7% by mass, and even more preferably 2 to 5% by mass. By the particle concentration in the other resin layer satisfying the above range, the flatness and scratch prevention property of the polyester layer (A) and the lubricity of the resin layer can be satisfied at the same time, and a more suitable film for a dry film resist substrate can be obtained.

[0071] The ratio of the particle concentration (mass %) in the other resin layer to the particle concentration (mass %) in the polyester layer (A) is preferably from 1 to 10,000, more preferably from 5 to 1,000, and still more preferably from 10 to 100.

[0072] The type and shape of the particles in the other resin layer are the same as those described for the particles contained in the polyester layer (A). Among them, inorganic particles, and among them, silica particles are preferred.

[0073] The above other resin layer preferably further contains an antistatic agent. When peeling the support film laminated on the photoresist layer, due to the static electricity generated by peeling electrification, foreign matters such as dust and dirt may be attracted to and adhered to the photoresist layer, resulting in irregular circuit patterns. Therefore, it is preferable to impart antistatic performance during support film peeling. By containing an antistatic agent in the above other resin layer, the polyester film can be made into a film for a dry film resist substrate for high resolution, having a high flat surface in contact with the photoresist layer, and having releasability and antistatic properties.

[0074] Examples of the antistatic agent used in the other resin layer include ion conductive polymer compounds such as ammonium group-containing compounds, polyether compounds, sulfonic acid compounds, and betaine compounds, and π-electron conjugated polymer compounds such as polyacetylene, polyphenylene, polyaniline, polypyrrole, polyisothianaphthene, and polythiophene. Among these, ion conductive polymer compounds are preferred, and ammonium group-containing compounds are particularly preferred. Resin layers formed from coating liquids containing π-conjugated conductive polymers, such as polythiophene and polyaniline, generally strongly color. Since the film for a dry film resist substrate is preferably highly transparent (low haze), π-conjugated conductive polymers may not be suitable. In addition, since π-conjugated conductive polymer coatings are generally more expensive than ion conductive coatings, ion conductive antistatic agents are preferably used from the viewpoint of manufacturing cost.

[0075] 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 components can be used.

[0076] Specific examples of such polymers include, for example, polymers having a constituent element represented by the following formula (1) as a repeating unit. This homopolymer or a copolymer obtained by copolymerizing a plurality of other components may also be used.

[0077]

Chemical formula

[0078] In the above formula (1), R 1 , R 2 are each independently a hydrogen atom, an alkyl group, a phenyl group, etc., and these alkyl groups and phenyl groups may be substituted with the groups shown below. The substitutable groups are, for example, a hydroxyl group, an amide group, an ester group, an alkoxy group, a phenoxy group, a naphthoxy group, a thioalkoxy group, a thiophenoxy group, a cycloalkyl group, a trialkylammonium alkyl group, a cyano group, a halogen, etc. Also, R 1 and R 2 may be chemically bonded. For example, -(CH 2 ) m -(m is an integer from 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 - etc. can be mentioned.

[0079] In the case of a polymer having the component represented by the above formula (1) as a repeating unit, from the viewpoint of enhancing compatibility with other materials and improving the transparency of the resulting coating film, it is preferably copolymerized with other repeating units. Examples of the 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-methylolacrylamide.

[0080] X in the above formula (1) - can be appropriately selected within a range not impairing the gist of the present invention. Examples thereof include halogen ions, sulfonates, phosphates, nitrates, alkyl sulfonates, carboxylates, and the like.

[0081] In addition, a polymer in which the component represented by the formula (1) and a polyethylene glycol-containing (meth)acrylate are copolymerized is preferable because the structure becomes flexible and a resin layer excellent in uniformity can be obtained during inline coating.

[0082] The number average molecular weight of the antistatic agent contained in the other resin layer is preferably from 1,000 to 500,000, more preferably from 2,000 to 350,000, and even more preferably from 5,000 to 200,000. If the number average molecular weight of the antistatic agent is 1,000 or more, the strength of the coating film can be maintained, the heat stability can also be maintained, and sufficient antistatic properties can be obtained. Further, if the molecular weight is 500,000 or less, an increase in the viscosity of the coating solution can be prevented, the handleability and coatability can be maintained well, and it becomes suitable as a film for a dry film resist substrate.

[0083] The other resin layer preferably contains wax in order to enhance the slipperiness of the film. At this time, it may be contained together with the above-described antistatic agent, or may contain wax without containing the antistatic agent. Examples of the wax that the other resin layer may contain include natural waxes such as plant waxes, animal waxes, mineral waxes, and petroleum waxes, and synthetic waxes such as synthetic hydrocarbons, modified waxes, and hydrogenated waxes. Among them, polyolefin-based compounds are preferable. Specifically, for example, compounds having a basic skeleton of a compound such as a polymer or copolymer of unsaturated hydrocarbons such as ethylene, propylene, 1-butene, and 4-methyl-1-pentene are dissolved or dispersed and used, and polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene copolymer, ethylene-1-butene copolymer, propylene-1-butene copolymer, etc. can be exemplified. More specifically, it is preferable to use a polyolefin having an active hydrogen group at the terminal and an acid value of 10 to 50, and further polyethylene oxide or polypropylene oxide.

[0084] When using a polymer type wax, its number average molecular weight is preferably 2000 to 20000, and more preferably 3000 to 15000. Within these ranges, film-forming properties and releasability can be maintained. Moreover, its softening point is preferably 70 to 170°C, and more preferably 90°C or higher or 150°C or lower. Within these ranges, film-forming properties and releasability can be maintained.

[0085] In order to improve the coating film strength of the other resin layer and impart abrasion resistance to the film, the other resin layer preferably further contains a crosslinking agent.

[0086] Examples of the crosslinking agent include melamine compounds, oxazoline compounds, epoxy compounds, isocyanate compounds, carbodiimide compounds, etc. Among these crosslinking agents, melamine compounds are preferred from the viewpoints of good coating film strength and excellent mold release property of the resin layer. Also, two or more of these crosslinking agents may be used in combination.

[0087] The above-mentioned melamine compound refers to a compound having a melamine skeleton in the compound. For example, alkylolated melamine derivatives, compounds obtained by reacting an alcohol with an alkylolated melamine derivative to partially or completely etherify, and mixtures thereof can be used. As the alcohol used for etherification, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butanol, isobutanol, etc. are preferably used. Also, the melamine compound may be either a monomer or a multimer of dimer or higher, or a mixture thereof may be used. Furthermore, those obtained by co-condensing urea or the like with a part of melamine can also be used, and it is also possible to use a catalyst to increase the reactivity of the melamine compound.

[0088] As the above-mentioned oxazoline compound, a polymer containing an oxazoline group is particularly preferred and can be prepared by polymerization of an addition-polymerizable oxazoline group-containing monomer alone or with other monomers. Examples of the addition-polymerizable oxazoline group-containing monomer 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, etc., and one or a mixture of two or more of these can be used.

[0089] Other monomers are not limited as long as they are copolymerizable with the addition polymerizable oxazoline group-containing monomer. For example, (meth)acrylic esters such as alkyl (meth)acrylates (as the alkyl group, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.); 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, methacrylonitrile, etc.; unsaturated amides such as (meth)acrylamide, N-alkyl (meth)acrylamide, N,N-dialkyl (meth)acrylamide (as the alkyl group, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.); vinyl esters such as vinyl acetate, vinyl propionate, etc.; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, etc.; α-olefins such as ethylene, propylene, etc.; halogen-containing α,β-unsaturated monomers such as vinyl chloride, vinylidene chloride, etc.; α,β-unsaturated aromatic monomers such as styrene, α-methylstyrene, etc. One or more of these monomers can be used.

[0090] Examples of the epoxy compound include condensates of epichlorohydrin with hydroxyl groups or amino groups such as ethylene glycol, polyethylene glycol, glycerin, polyglycerin, bisphenol A, etc., and there are polyepoxy compounds, diepoxy compounds, monoepoxy compounds, glycidylamine compounds, etc.

[0091] Examples of the polyepoxy compound include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyl tris(2-hydroxyethyl) isocyanate, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether. Examples of the diepoxy compound include neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, resorcin diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether. Examples of the monoepoxy compound include allyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether. Examples of the glycidylamine compound include N,N,N’,N’-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N-diglycidylamino)cyclohexane, etc.

[0092] Note that the crosslinking agent is preferably used in a design to improve the performance of the resin layer by reacting it during the drying process or film-forming process. It can be presumed that unreacted substances of these crosslinking agents, compounds after reaction, or mixtures thereof are present in the formed resin layer.

[0093] For improving the adhesion to the polyester film and the like, other resin layers may contain thermoplastic resins such as polyesters, polyurethanes, acrylic resins, polyvinyl resins, polyolefins, and / or thermosetting resins such as thermosetting acrylic resins, melamine resins, and epoxy resins as binders.

[0094] The mass ratio of the particles contained in the other resin layer, the antistatic agent, wax, binder, and crosslinking agent that the resin layer may further contain is preferably adjusted as appropriate depending on the selected compound, and the criteria are as follows.

[0095] The content (particle concentration) of the particles in the other resin layer is preferably 1% by mass or more, more preferably 2% by mass or more or 10% by mass or less. When the content (particle concentration) of the particles in the other resin layer is 1% by mass or more, it becomes easier to obtain the lubrication improvement and winding improvement effects of the film for the dry film resist base material. When it is 10% by mass or less, the particles are less likely to aggregate, the scraping of the resin layer due to particle detachment can be reduced, the light transmission of the film for the dry film resist base material is less likely to be inhibited, and circuit defects are less likely to occur.

[0096] The content of the antistatic agent in the other resin layer is preferably 5% by mass or more, more preferably 10% by mass or more and 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, more preferably 20% by mass or more and 90% by mass or less. When the content of the antistatic agent is within the above range, a sufficient surface resistivity can be achieved, and the film for the dry film resist base material is less likely to adhere electrostatically.

[0097] The content of the wax in the resin layer is preferably 1% by mass or more, more preferably 2% by mass or more and 10% by mass or less. When the content of the wax is within the above range, it is easy to achieve a sufficient lubrication effect and it is difficult to inhibit the adhesion to the polyester film.

[0098] The content of the crosslinking agent in the resin layer forming composition constituting the other resin layer is preferably 1% by mass or more, more preferably 2% by mass or more or 50% by mass or less. When the content of the crosslinking agent is 1% by mass or more, the lubrication improvement and winding improvement effects of the film for the dry film resist base material are easily obtained. When it is 50% by mass or less, the light transmission of the film for the dry film resist base material is less likely to be inhibited, and circuit defects are less likely to occur.

[0099] The content of the binder in the other resin layer is preferably 1% by mass or more, more preferably 2% by mass or more or 60% by mass or less. By having the content of the binder within the above range, sufficient adhesion to the polyester film can be obtained.

[0100] The other resin layer can also 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.

[0101] The analysis of the components of the other resin layer can be performed by analysis such as TOF-SIMS, X-ray photoelectron spectroscopy (XPS), and X-ray fluorescence.

[0102] The film thickness of the other resin layer is preferably 0.001 μm to 0.5 μm, more preferably in the range of 0.005 μm or more or 0.3 μm or less, and even more preferably in the range of 0.01 μm or more or 0.2 μm or less. If the film thickness of the other resin 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 if the film thickness is 0.001 μm or more, sufficient release properties can be obtained. Also, if the film thickness of the other resin layer is 0.001 to 0.5 μm, it will not affect the surface roughness of the polyester film. That is, it can be regarded that the surface roughness of the polyester film is the same as that of the polyester film laminated with the other resin layer.

[0103] <Method for manufacturing polyester film> The method for manufacturing the polyester film in the present invention will be described. The production of the polyester film of the present invention includes the following production steps 1 and 2. Production step 1 is a step of filtering, in advance, a melt of a polyester resin chip containing a titanium compound that has been made into a masterbatch, through a filter medium containing a powder sintered body and a filter medium containing a fibrous sintered body with a filtration accuracy of 5 μm or less. The melting of the polyester resin chip in production step 1 can be performed, for example, using an extruder. Manufacturing process 2 is a process of manufacturing a polyester film using the polyester resin melt obtained in manufacturing process 1. The polyester resin melt obtained in manufacturing process 1 has had foreign matters removed, and is co-extruded onto a rotary cooling drum from all the die lips (e.g., a T-die, etc.) and rapidly cooled to produce an unstretched laminated film. Subsequently, the unstretched laminated film is stretched in the longitudinal and transverse directions, and heat-set as necessary, thereby enabling production. At this time, it is preferable that the draw ratio in the transverse direction, in other words, the width direction, is 4.0 times or more, and it is more preferable that the draw ratio in the longitudinal direction is also 2.5 times or more as necessary.

[0104] (Foreign matter removal) From the perspective of removing foreign matters and additives (aggregates such as fine particles) in the polyester molten resin, it is preferable to provide a filtration filter after melt extrusion for foreign matter removal. As filtration by the filter, for example, it is preferable to use a filtration device incorporating a breaker plate type or a leaf disk type filter. The filtration may be performed in one stage, or may be performed in multiple stages of two or more stages. The filter medium is preferably stainless steel. As the configuration of the filter medium, those knitted from wire rods, those sintered from metal fibers or metal powders (sintered filter media) can be used, and among them, sintered filter media are preferable. In the present invention, by using a fibrous sintered body using sintered fibers and a filter medium including a specific fibrous sintered body with a filtration accuracy of 5 μm or less, preferably 3 μm or less, and a filter medium including a powdered sintered body using sintered powder, it becomes possible to remove gel-like foreign matters in the polyester resin. Particularly in the present invention, from the perspective of improving the filtration accuracy, it is preferable to apply a filter of a fibrous sintered body. More preferably, it is good to combine a powdered sintered body using sintered powder, which is effective for removing gel-like foreign matters, with the fibrous sintered body. Among them, in particular, it is preferable to use a filtration device including at least one filter in which both are integrated. As the filter including the above filter medium, a leaf disk type filter is preferable. The number of filter sheets containing the above filter medium, their size, etc. are appropriately selected according to the properties (type, viscosity, flow rate, etc.) of the polyester resin to be used. The filtration accuracy of the filter medium containing the specific fibrous sintered body is preferably 2 μm or less. In the present invention, "filtration accuracy" is defined as "the minimum glass bead diameter capable of capturing 95% or more by using the filter medium". In the present invention, the polyester resin melt that has undergone the filtration step by the filter preferably has 350 or fewer aggregates (foreign substances) with a major axis of 1 μm or more and less than 3 μm per cm 2 and more preferably 300 or fewer per cm 2 and even more preferably 200 or fewer per cm 2 and particularly preferably 100 or fewer per cm 2 among them.

[0105] Next, an example of a method for manufacturing a polyester film composed of three layers of polyester layer (A) / polyester layer (B) / polyester layer (A) will be described. The same applies to those with other laminated structures. First, the polyester for forming the polyester layer (A) and the polyester for forming the polyester layer (B) are supplied to separate extruders, heated to a temperature above the melting point of each polyester, and melted respectively. Next, each polyester is extruded as a sheet from a T-die so as to be laminated in the order of polyester layer (A) / polyester layer (B) / polyester layer (A). Subsequently, this sheet is rapidly cooled 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 may be improved by an electrostatic printing adhesion method, a liquid coating adhesion method, or the like.

[0106] Next, an unoriented film is longitudinally oriented (longitudinal orientation) using a roll stretching machine to obtain a uniaxially oriented film. At this time, the stretching temperature is equal to or higher than the glass transition temperature of the polyester, preferably 70 to 150 °C, more preferably 75 to 130 °C. Also, the longitudinal orientation ratio is 2.5 times or more, particularly preferably 2.8 times or more and 4.0 times or less, and even more preferably 3.0 times or more and 3.5 times or less. At this time, the longitudinal orientation may be performed in only one step, or may be performed in two or more steps. Subsequently, a biaxially oriented film is obtained by laterally orienting (transverse orientation) the uniaxially oriented film using a tenter stretching machine. At this time, the stretching temperature is preferably 75 to 150 °C, more preferably 80 to 140 °C. Also, the transverse orientation ratio is preferably 4.0 times or more, particularly preferably 4.2 times or more and 6.0 times or less, and even more preferably 4.4 times or more and 5.5 times or less, and most preferably 4.5 times or more and 5.0 times or less. At this time, the transverse orientation may be performed in only one step, or may be performed in two or more steps.

[0107] Subsequently, a laminated film is produced by heat-treating the biaxially oriented film at a temperature of, for example, 150 to 250 °C. When heat-treating the biaxially oriented film, the biaxially oriented film may be relaxed by 30% or less. Then, it may be wound into a roll as necessary.

[0108] The formation of other resin layers may be formed by "in-line coating" that treats the film surface during the manufacturing process of the polyester film, or "off-line coating" that is applied outside the system on the once-manufactured polyester film may be employed.

[0109] In-line coating is a method of performing coating within the manufacturing process of the polyester film. Specifically, it is a method of performing coating at any stage from when the polyester is melt-extruded until after stretching and heat-setting and winding up. Usually, coating is performed on any one of the unstretched sheet obtained by melting and quenching, the uniaxially oriented film that has been stretched, the biaxially oriented film before heat-setting, and the film before winding up after heat-setting.

[0110] For example, in sequential biaxial stretching, a method of stretching in the transverse direction after coating, particularly on a uniaxially stretched film stretched in the longitudinal direction (vertical direction), is excellent. According to such a method, film formation and resin layer formation can be performed simultaneously, so there is an advantage in terms of manufacturing cost. Also, since stretching is performed after coating, the film thickness of the resin layer can be changed according to the stretching ratio, and it is possible to more easily make the coating thinner compared to offline coating. Further, by providing a resin layer on the polyester film before stretching, the resin layer can be stretched together with the polyester film. Thereby, the resin layer can be firmly adhered to the polyester film. Furthermore, in the production of biaxially stretched polyester films, by stretching while gripping the film ends with clips or the like, the film can be restrained in the longitudinal and transverse directions, and in the heat setting step, a high temperature can be applied while maintaining flatness without wrinkles. Therefore, since the heat treatment applied after coating can be set to a high temperature that cannot be achieved by other methods, the film-forming property of the resin layer is improved, and the resin layer and the film can be more firmly adhered. Furthermore, a strong resin layer can be obtained, and the performance and durability of the resin layer can be improved. Therefore, as a method of forming a resin layer on at least one side of a polyester film, a manufacturing method of applying a coating solution to the polyester film and then stretching it in at least one direction is preferable.

[0111] As a method of forming the resin layer, for example, particles and an antistatic agent, wax, binder, crosslinking agent, etc. that the resin layer may further contain are dispersed or dissolved in a solvent to prepare a solution for the resin layer, and it can be formed by applying it to one side of a base polyester film.

[0112] The solution for the resin layer is preferably formed by applying it as an aqueous coating liquid (a water-soluble resin or a water-dispersible resin using water as a medium) to one side of the polyester film. However, it is also possible to form it by applying an aqueous coating liquid containing a small amount of an organic solvent. Examples of such organic solvents 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; esters such as ethyl acetate; amines such as dimethylethanolamine; and the like. These can be used alone or in combination. By appropriately selecting and incorporating these organic solvents into the aqueous coating solution as needed, the stability, coatability, or coating film properties of the coating solution can be enhanced.

[0113] As a method for applying the resin layer solution to the polyester film, for example, a reverse roll coater, a gravure coater, a rod coater, an air doctor coater, or other coating devices as shown in "Coating Methods" written by Yuji Harasaki and published by Maki Shoten in 1979 can be used.

[0114] Regarding the drying and curing conditions when forming the resin layer on the polyester film, for example, when providing the resin layer by offline coating, usually, heat treatment is preferably performed at 80 to 200°C for 3 to 40 seconds, more preferably at 100 to 180°C for 3 to 40 seconds as a reference. On the other hand, when providing the resin layer by inline coating, usually, heat treatment is preferably performed at 70 to 270°C for 3 to 200 seconds as a reference.

[0115] Also, regardless of whether it is offline coating or inline coating, heat treatment and irradiation with active energy rays such as ultraviolet rays can 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.

[0116] Next, the characteristics of the polyester film in the present invention will be described.

[0117] (Surface roughness) The average surface roughness Ra of the polyester film surface is preferably in the range of 0.001 to 0.020 μm, more preferably 0.002 μm or more and 0.010 μm or less, and even more preferably 0.003 μm or more and 0.005 μm or less. 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 less likely to increase. Therefore, a decrease in the exposure amount of ultraviolet rays (UV) can be suppressed, and a decrease in resolution can be suppressed. When the resin layer is formed on only one side, it is preferably formed on the side opposite to the photoresist layer formation side of the polyester film. Therefore, the above average surface roughness Ra is preferably provided on the surface of the polyester layer A side of the polyester film. The same applies to the maximum surface roughness Rt described below.

[0118] The maximum surface roughness Rt is preferably in the range of 0.010 to 0.400 μm, more preferably 0.015 μm or more and 0.300 μm or less, even more preferably 0.020 μm or more and 0.200 μm or less, and even more preferably 0.025 μm or more and 0.100 μm or less. If Rt is 0.400 μm or less, it is possible to prevent the transfer of unevenness to the photoresist layer, and the problem of causing circuit defects during the formation of a fine pitch circuit can be solved. 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, it is difficult for scratches to occur on the film surface for the dry film resist base material, especially in the film forming process. Furthermore, it is preferable because scratch transfer to the photoresist layer and exposure scattering due to the scratches are less likely to occur, and it is less likely to affect the fine pitch circuit pattern.

[0119] (Film haze) From the viewpoint of making it difficult for the exposure amount of ultraviolet rays to be insufficient when used in a high-resolution dry film resist, less likely to cause defects in a desired circuit, and suppressing a decrease in resolution, the film haze is preferably 1.0% or less, more preferably 0.1% or more and 0.7% or less, and even more preferably 0.2% or more and 0.5% or less.

[0120] (Number of aggregates (foreign substances) in the polyester film having a major axis of 1 μm or more and less than 3 μm) The number of aggregates (foreign substances) in the polyester film having a major axis of 1 μm or more and less than 3 μm is 350 pieces / cm 2 It is necessary to be. Preferably 300 pieces / cm 2 or less, more preferably 200 pieces / cm 2 or less, especially 100 pieces / cm 2 or less is good.

[0121] (Number of protrusions with a maximum peak height (Sp) protruding from the film surface of 0.3 μm or more) The number of protrusions with a maximum peak height (Sp) protruding from the film surface of 0.3 μm or more is 2.7 pieces / cm 2 It is preferably below. More preferably 2.2 pieces / cm 2 or less, further preferably 1.7 pieces / cm 2 or less, especially 1.0 pieces / cm 2 or less is good.

[0122] The maximum peak height (Sp) is one of the surface roughness parameters (ISO 25178), represents the maximum value of the height from the average surface of the surface, and is expressed by the following formula (2).

[0123]

Equation

[0124] In the present invention, by satisfying the above number of protrusions, even if the line width of the resist further progresses from 5 μm or less to 2 μm or less and further miniaturization progresses, it becomes possible to cope.

[0125] <Method of using the polyester film> The polyester film in the present invention can be used for a support film for a dry film resist, a support film for manufacturing a ceramic green sheet, a base film for optics, etc.

[0126] (Film for dry film resist substrate) The polyester film of the present invention is useful as a film for manufacturing dry film resist. Specifically, 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, etc.

[0127] At this time, when the resin layer is formed only on one side of the polyester film, when forming the dry film resist, the resin layer is located on the surface of the polyester film opposite to the surface on which the photoresist layer is formed. In other words, it is preferable to laminate the polyester film on the photoresist layer so that it adheres closely to the photoresist layer on the surface of the polyester film on the side opposite to the resin 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 in a roll shape, the lower surface of the dry film resist, that is, the support film, comes into contact with the upper surface side protective film. Therefore, the effect of lubricity is more remarkable when there is a resin layer on the surface in contact with the protective film. Also, since there is no resin layer on the resist surface, the adhesion between the resist and the support film is less likely to change, and peeling defects are less likely to occur when removing the support film from the resist.

[0128] As the photosensitive resin composition constituting the photoresist layer, conventional compositions can be used. Usually, as the photosensitive resin contained in the photosensitive resin composition for dry film resist, a negative photosensitive resin is used, and it mainly consists of a composition containing a monomer having a polymerizable unsaturated group, a polymer, a photoinitiator, etc. The photosensitive resin generally has alkali solubility in water, and the exposed part in the dry film resist processing step forms a circuit by development, and the unexposed part is removed by the developer.

[0129] The monomer having a polymerizable unsaturated group is not particularly limited, and examples include monomers having one polymerizable unsaturated group, monomers having two polymerizable unsaturated groups, and monomers having three or more polymerizable unsaturated groups. These can be used alone or in appropriate combination.

[0130] Examples of the monomer having one polymerizable unsaturated group include methyl (meth)acrylate, ethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, propyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, butyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-phenoxy-2-hydroxypropyl (meth)acrylate, 2-(meth)acryloyloxy-2-hydroxypropyl phthalate, 3-chloro-2-hydroxypropyl (meth)acrylate, glycerin mono(meth)acrylate, 2-(meth)acryloyloxyethyl acid phosphate, half (meth)acrylate of phthalic acid derivative, N-methylol (meth)acrylamide, and the like.

[0131] 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, propylene glycol di(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, phthalic acid diglycidyl ester di(meth)acrylate, hydroxypivalic acid-modified neopentyl glycol di(meth)acrylate, and the like. 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.

[0132] Examples of the monomer having three or more polymerizable unsaturated groups include trimethylolpropane tri(meth)acrylate, trimethylolpropane tripropoxy(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, tri(meth)acryloyloxyethoxytrimethylolpropane, glycerin polyglycidyl ether poly(meth)acrylate, and the like.

[0133] In addition to the above, epoxy (meth)acrylate-based compounds, urethane (meth)acrylate-based compounds, phosphorus element-containing polymerizable compounds, etc. may also be used.

[0134] As the monomer having a polymerizable unsaturated group, those having two polymerizable unsaturated groups and a weight average molecular weight of 1500 or less, preferably 300 to 1200, are preferred. Among them, ethylene oxide-modified bisphenol A type di(meth)acrylate and ethylene oxide / propylene oxide-modified bisphenol A type di(meth)acrylate are preferably used. When the weight average molecular weight exceeds 1,500, the crosslinking distance may become long and sufficient curing may not be obtained, which may lead to a decrease in resolution and a decrease in fine line adhesion.

[0135] The polymer contained in the photosensitive resin composition is not particularly limited, but examples include polymers composed of acrylic or methacrylic polymerizable monomers. A homopolymer or a copolymer, or a copolymer with a polymerizable monomer other than acrylic or methacrylic monomers may be used. Examples of the polymerizable monomer include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid, or their anhydrides, half esters, (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, glycidyl (meth)acrylate, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, vinyl acetate, and alkyl vinyl ether.

[0136] 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. When the weight average molecular weight is less than 5,000, the resin may become too soft and bleeding of the resin may occur when processed into a roll form as a photoresist film. When it exceeds 250,000, the resolution may decrease.

[0137] The glass transition temperature (Tg) of the above polymer preferably ranges from 30 to 150°C. If the glass transition temperature is less than 30°C, the resin may become too soft, and bleeding of the resin may occur when processed into a roll form as a photoresist film. If it exceeds 150°C, the followability to the unevenness of the substrate surface when used as a photoresist film may decrease.

[0138] As the photoinitiator contained in the photosensitive resin composition, conventionally known ones are used.

[0139] In addition, amino resins such as melamine, thermosetting agents such as isocyanate compounds, coloring dyes such as crystal violet, malachite green, malachite green lake, brilliant green, patent blue, methyl violet, victoria blue, rose aniline, para fuchsine, ethylene violet, adhesion promoters, plasticizers, antioxidants, thermal polymerization inhibitors, solvents, surface tension modifiers, stabilizers, chain transfer agents, defoamers, flame retardants, and other additives can be added to the photosensitive resin composition.

[0140] When a photosensitive resin layer (photoresist layer) is formed by providing a photosensitive resin composition on a polyester film, a method of mixing an organic solvent with the photosensitive resin composition to a predetermined concentration and using it can be mentioned. 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, etc. These can be used alone or in combination of two or more. A coating solution containing a mixture of the photosensitive resin composition is uniformly coated on one side of a support film by a method such as a roll coater method or a bar coater method, and usually dried at 50 to 130°C or in an oven with sequentially increasing temperature to form a photosensitive resin layer (photoresist layer). A protective film is laminated on the photosensitive resin layer and wound into a roll to produce a photosensitive resin laminate (dry film resist).

[0141] The protective film that constitutes the dry film resist is formed of polyolefins such as polyethylene and polypropylene, polyester, etc., and can protect the photoresist layer by being laminated on the opposite surface of the support film side in the photoresist layer.

[0142] 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 substrate, has a reduced number of aggregates (foreign substances) in the support film, and it is difficult for the hardening inhibition of the resist to occur. Therefore, circuit defects generated in the electronic circuit board can be reduced, and it is suitable for forming high-definition electronic circuits.

[0143] (Support for manufacturing ceramic green sheet) The polyester film of the present invention is useful as a film for manufacturing a ceramic green sheet. Specifically, when manufacturing a ceramic green sheet, after applying a ceramic slurry to the release surface of the release film, it is dried and cured, peeled off from the release film, and a ceramic green sheet is laminated to manufacture a ceramic capacitor. The release layer that constitutes the release film is not particularly limited as long as it contains a material having releasability. Among such materials, it is preferable to use a curable silicone resin because the releasability becomes particularly good. A type mainly composed of a curable silicone resin may be used, or a modified silicone type obtained by graft polymerization with an organic resin such as a urethane resin, an epoxy resin, or an alkyd resin may be used. As the type of the curable silicone resin, any curing reaction type such as an addition type, a condensation type, an ultraviolet curing type, an electron beam curing type, or a solvent-free type can be used. The coating amount (after drying) of the release layer is in the range of 0.01 to 5 g / m 2 , and further preferably in the range of 0.01 to 2 g / m 2 , and particularly preferably in the range of 0.01 to 1 g / m 2 .

[0144] When the polyester film in the present invention is used as a support for manufacturing a ceramic green sheet, the surface of the film has high smoothness, and pinholes and the like are less likely to occur during the application of the ceramic slurry. For example, it can be used for forming a thin-film ceramic green sheet with a thickness of 3 μm or less.

[0145] (Film for forming interlayer insulating layer) The polyester film of the present invention is useful as a film for forming an interlayer insulating layer. Specifically, a laminate can be formed by laminating an interlayer insulating layer on the polyester film in the present invention and laminating a protective film on the interlayer insulating layer. The insulating layer resin composition constituting the insulating layer preferably contains an epoxy resin and an inorganic filler. The polyester film with an insulating layer in the present embodiment is obtained by applying a coating solution composed of the above insulating layer resin composition to the surface of the resin layer (release layer) of the polyester film and curing it. The configuration of the protective film is not particularly limited as long as it can suppress damage or deformation of the insulating layer. As the protective film substrate, a resin film is preferable. More specifically, a film mainly composed of polyolefin such as polyethylene and polypropylene, polyester such as polyethylene terephthalate and polyethylene naphthalate, polyimide or polycarbonate is preferable.

[0146] When the polyester film in the present invention is used as a film for forming an interlayer insulating layer, the surface of the film has high smoothness and can be used for forming a highly smooth interlayer insulating layer.

[0147] (Optical film) The polyester film of the present invention is useful as an optical film. Specifically, when an adhesive layer is provided on the polyester film in the present invention to manufacture an adhesive sheet, it has high transparency. For example, when it is adhered to an adherend, it has advantages such as good workability, such as being able to perform foreign matter inspection.

[0148] <Explanation of statements, etc.> Generally, according to the definition in JIS, a "sheet" refers to a thin product with a thickness that is small compared to its length and width and is flat. Generally, a "film" refers to a thin, flat product with a thickness that is extremely small compared to its length and width, and its maximum thickness is arbitrarily limited, and it is usually supplied in the form of a roll (Japanese Industrial Standard JIS K6900). However, the boundary between a sheet and a film is not clear, and since there is no need to distinguish between the two in the context of this invention, in this invention, when referring to a "film", it includes a "sheet", and when referring to a "sheet", it also includes a "film". Also, when expressing as a "panel" such as an image display panel, a protection panel, etc., it includes a plate, a sheet, and a film.

[0149] In this specification, when described as "X~Y" (X and Y are arbitrary numbers), unless otherwise specified, it includes the meaning of "X or more and Y or less", and also includes the meaning of "preferably larger than X" or "preferably smaller than Y". Also, when described as "X or more" (X is an arbitrary number), unless otherwise specified, it includes the meaning of "preferably larger than X", and when described as "Y or less" (Y is an arbitrary number), unless otherwise specified, it also includes the meaning of "preferably smaller than Y".

Example

[0150] Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited to the following examples as long as it does not exceed the gist thereof.

[0151] <Forming material of polyester film> In the examples and comparative examples, the following polyesters were used to produce polyester films (polyester layer (A), polyester layer (B)).

[0152] <Polyester I> A polyethylene terephthalate homopolymer using ethyl acid phosphate, magnesium acetate tetrahydrate, and tetra-n-butyl titanate as a polymerization catalyst. The intrinsic viscosity of Polyester I was 0.70 dl / g. (Ti element: 10 ppm) (P element: 15 ppm), (Mg element: 15 ppm)

[0153] <Polyester II> A polyethylene terephthalate homopolymer using ethyl acid phosphate, magnesium acetate tetrahydrate, and tetra-n-butyl titanate as a polymerization catalyst. The intrinsic viscosity of Polyester II was 0.63 dl / g. (Ti element: 10 ppm), (P element: 15 ppm), (Mg element: 15 ppm)

[0154] <Polyester III> A polyethylene terephthalate homopolymer using ethyl acid phosphate, magnesium acetate tetrahydrate, and antimony trioxide as a polymerization catalyst. The intrinsic viscosity of Polyester III was 0.63 dl / g. (Sb element: 310 ppm) (P element: 30 ppm), (Mg element: 30 ppm)

[0155] <Polyester IV> A polyethylene terephthalate homopolymer using ethyl acid phosphate, magnesium acetate tetrahydrate, and tetra-n-butyl titanate and antimony trioxide as a polymerization catalyst. The intrinsic viscosity of Polyester IV was 0.63 dl / g. (Ti element: 6 ppm, Sb element: 95 ppm), (P element: 40 ppm), (Mg element: 40 ppm)

[0156] <Polyester V> A polyethylene terephthalate homopolymer using ethyl acid phosphate, magnesium acetate tetrahydrate, and tetra-n-butyl titanate, and containing spherical alumina particles. The intrinsic viscosity of Polyester V was 0.61 dl / g, the average particle size of the spherical alumina particles was 0.05 μm, the maximum particle size was 0.20 μm, and the content of the spherical alumina particles was 1.5% by mass based on the whole Polyester V. (Ti element: 10 ppm), (P element: 15 ppm), (Mg element: 15 ppm)

[0157] <Polyester VI> A polyethylene terephthalate homopolymer containing spherical silica particles, using ethyl acid phosphate, magnesium acetate tetrahydrate, and tetra-n-butyl titanate as a polymerization catalyst. The intrinsic viscosity of Polyester VI was 0.61 dl / g, the average particle size of the spherical silica particles was 0.30 μm, the maximum particle size was 0.60 μm, and the content of the spherical silica particles was 1.0% by mass based on the whole Polyester VI. (Ti element: 10 ppm), (P element: 15 ppm), (Mg element: 15 ppm)

[0158] <Polyester VII> A polyethylene terephthalate homopolymer containing ion exchange resin particles, using ethyl acid phosphate, magnesium acetate tetrahydrate, and tetra-n-butyl titanate as a polymerization catalyst. The intrinsic viscosity of Polyester VII was 0.61 dl / g, the average particle size of the ion exchange resin particles was 0.50 μm, the maximum particle size was 0.80 μm, and the content of the ion exchange resin particles was 1.0% by mass based on the whole Polyester VII. (Ti element: 10 ppm), (P element: 15 ppm), (Mg element: 15 ppm)

[0159] <Polyester VIII> A polyethylene terephthalate homopolymer containing ion exchange resin particles, using ethyl acid phosphate, magnesium acetate tetrahydrate, and tetra-n-butyl titanate as a polymerization catalyst. The intrinsic viscosity of Polyester VIII was 0.61 dl / g, the average particle size of the ion exchange resin particles was 0.8 μm, the maximum particle size was 1.5 μm, and the content of the ion exchange resin particles was 0.5% by mass based on the whole Polyester VIII. (Ti element: 10 ppm), (P element: 15 ppm), (Mg element: 15 ppm)

[0160] <Polyester IX> Ethyl acid phosphate, magnesium acetate tetrahydrate, and tetra-n-butyl titanate as a polymerization catalyst were used to prepare a polyethylene terephthalate homopolymer containing silica particles. The intrinsic viscosity of Polyester IX was 0.61 dl / g, the average particle size of the silica particles was 2.7 μm, the maximum particle size was 4.0 μm, and the content of the spherical silica particles was 0.7% by mass based on the whole Polyester IX. (Ti element: 10 ppm), (P element: 15 ppm), (Mg element: 15 ppm)

[0161] <Polyester X> Ethyl acid phosphate, magnesium acetate tetrahydrate, and tetra-n-butyl titanate as a polymerization catalyst were used to prepare a polyethylene terephthalate homopolymer. The intrinsic viscosity of Polyester X was 0.63 dl / g. (Ti element: 10 ppm), (P element: 60 ppm), (Mg element: 60 ppm)

[0162] <Composition for forming resin layer> In the following Examples and Comparative Examples, the following raw materials were used and blended at the mass ratios shown in Table 2 to prepare a coating liquid as a composition for forming a resin layer.

[0163] Antistatic agent (A1) Polydiallyldimethylammonium chloride (average molecular weight: about 30,000)

[0164] Wax (B1) In an emulsification equipment with a capacity of 1.5 L equipped with a stirrer, a thermometer, and a temperature controller, 300 g of oxidized polyethylene wax with a melting point of 105°C, an acid value of 16 mgKOH / g, a density of 0.93 g / mL, and an average molecular weight of 5000, 650 g of ion-exchanged water, 50 g of decaglycerin monooleate surfactant, and 10 g of 48% potassium hydroxide aqueous solution were added. After purging with nitrogen, it was sealed and stirred at high speed at 150°C for one hour, then cooled to 130°C and passed through a high-pressure homogenizer at 400 atmospheres to obtain a wax emulsion cooled to 40°C.

[0165] Particles (C1): Silica particles with an average particle size of 0.05 μm Particles (C2): Silica particles with an average particle size of 0.08 μm The average particle sizes of particles (C1) to (C2) were determined using a transmission electron microscope (manufactured by Hitachi High-Technologies Corporation, model H7650, acceleration voltage 100 kV).

[0166] Acrylic aqueous dispersion (D1) An acrylic resin aqueous dispersion polymerized with the following composition and having a glass transition temperature of 40°C Emulsion polymer of ethyl acrylate / n-butyl acrylate / methyl methacrylate / N-methylolacrylamide / acrylic acid = 65 / 21 / 10 / 2 / 2 (mass%) (emulsifier: anionic surfactant)

[0167] Crosslinking agent (E1): Hexamethoxymethylol melamine

[0168] <Example 1> As the polyester layer A, polyester I and polyester V were blended at a mass ratio of 80:20, melted in an extruder, and supplied to the polyester layer A of the lamination die. As the polyester layer B, 100% by mass of polyester I was melted in an extruder and supplied to the polyester layer B of the lamination die. Regarding the two-layer three-layer laminated polyester resin having a structure of A layer / B layer / A layer, 100 sets of laminated filters equipped with a filter medium containing a powder sintered body and a filter medium containing a fibrous sintered body with a filtration accuracy of 3 μm or less were set, and after passing through a manufacturing process of filtration, they were co-extruded into a film form, cast onto a cooling drum at 35 °C, adhered to the surface of the cooling drum by an electrostatic adhesion method, and a non-stretched film that was rapidly cooled and solidified was produced. Next, the non-stretched film was preheated with a heating roll at 75 °C, then longitudinally stretched 3.2 times between rolls at 85 °C using an infrared heating heater and a heating roll in combination. Then, a coating liquid as a resin layer forming composition prepared with the formulation shown in Table 2 was in-line coated on one side of this longitudinally stretched film. Next, the film ends were gripped with clips and guided into a tenter, heated at a temperature of 95 °C, and stretched 4.5 times in the transverse direction. Heat treatment was performed at 225 °C for 10 seconds to produce a polyester film (sample) having a resin layer with a thickness of 16.0 μm (A layer / B layer / A layer = 1.0 μm / 14.0 μm / 1.0 μm), a width of 1580 mm, and a surface thickness of 0.030 μm.

[0169] <Examples 2 to 4, Comparative Examples 1 to 4> As shown in Table 2, a polyester film (sample) was produced in the same manner as in Example 1, except that the raw materials of the polyester film were changed, the polyester raw materials were not filtered, the filtration mesh was changed, or the resin layer was not provided.

[0170] <Measurement Method and Evaluation Method> The measurement methods and evaluation methods for the physical property values of the materials and polyester films (samples) used in the above examples and comparative examples are as follows.

[0171] (1) Thickness of the polyester film The thickness of the polyester film (sample) was measured with a micrometer.

[0172] (2) Thickness of each layer of the polyester film and resin layer thickness The thickness of each layer of the polyester film (polyester layer A and polyester layer B) and the resin layer thickness were measured by observing the film cross-section with a transmission electron microscope (TEM). Specifically, first, a small piece of the film sample was embedded in a resin prepared by blending a curing agent and an accelerator with epoxy resin, and a section with a thickness of 200 nm was prepared with an ultramicrotome to obtain an observation sample. The obtained sample was observed with a transmission electron microscope (H-9000) manufactured by Hitachi High-Technologies Corporation. Among the observed cross-sections, the interfaces between polyester layer A and polyester layer B and the interface between the polyester film surface and the resin layer were observed by light and dark contrast, almost parallel to the polyester film. The distances from these interfaces to the film surface were measured for 50 transmission electron micrographs, and 10 points with larger measured values and 10 points with smaller measured values were deleted, and the average of 30 points was used as the measured value. The thickness of each layer and the resin layer thickness were determined from the average value. However, for the transmission electron microscope, the acceleration voltage was 300 kV, and the magnification was set in the range of 1 to 100,000 times according to the layer thickness.

[0173] (3) Antimony element and titanium element contents in the polyester film In each example and comparative example, using a fluorescent X-ray analyzer (manufactured by Shimadzu Corporation, model "XRF-1800"), the elemental amounts in the film were determined by single measurement under the conditions shown in Table 1 below. In the case of the film, the film was melted and molded into a disk shape for measurement, and the contents of the antimony element (Sb) and titanium element (Ti) in the entire film were measured.

[0174]

Table 1

[0175] (4) Number of aggregates (foreign substances) in the polyester film with a major axis of 1 μm or more and less than 3 μm In each of the examples and comparative examples, the inside of the polyester film was observed using an optical microscope. The obtained image was binarized using image processing software (manufactured by Nireco Corporation, "LUZEX"). Aggregates (foreign substances) in the film could be confirmed as black, and the aggregates (foreign substances) were extracted by binarizing the obtained image. 1.3 cm 2 The number of aggregates (foreign substances) with a major axis of 1 μm or more and less than 3 μm in an area of was counted and converted to 1 cm 2

[0176] (5) Number of protrusions with a maximum peak height (Sp) protruding from the film surface of 0.3 μm or more Measurement was performed using a white interferometer "NewView" (registered trademark) manufactured by Ametek Japan Co., Ltd. Using a lens magnification of 10 times and a zoom of 0.5 times, the maximum peak height Sp value per 1 field of view = 1.83 mm × 1.83 mm area was measured, and the measurement was repeated sequentially so that the measurement locations did not overlap, for a total of 180 times (total measurement area = 602.8 mm 2 ) to obtain the maximum peak height (Sp) value. The Sp values of 0.3 μm or more were counted from the 180 Sp values (number / 602.8 mm 2 ) and converted to the number of protrusions of 0.3 μm or more (number / cm 2 )

[0177] (6) Average surface roughness (Ra) of the film surface ​When there is a resin layer, the average surface roughness (Ra) of the film surface on the side opposite to the resin layer, that is, the surface on the polyester layer (A) side, was determined as follows using a surface roughness measuring instrument (SE-3F) manufactured by Kosaka Laboratory Ltd. That is, a portion with a reference length L (2.5 mm) in the direction of the center line was extracted from the film cross-sectional curve obtained by measurement. When the center line of this extracted portion was taken as the x-axis and the direction of the vertical magnification was taken as the y-axis, and represented by the roughness curve y = f(x), the value given by the following formula was expressed in [μm]. The center line average roughness was represented by the average value of the center line average roughness of the extracted portions obtained from these cross-sectional curves, where 10 cross-sectional curves were obtained from the sample film surface. The tip radius of the stylus was 2 μm, the load was 30 mg, and the cut-off value was 0.08 mm.

[0178] (7) Maximum height (Rt) of the film surface The maximum height (Rt) of the film surface, similar to the average surface roughness (Ra), was measured as follows. When the extracted portion of the cross-sectional curve obtained during Ra measurement was sandwiched by two straight lines parallel to its average line, the distance between these two straight lines was measured in the direction of the vertical magnification of the cross-sectional curve, and the value expressed in micrometers (μm) was defined as the maximum height Rt of the extracted portion. The maximum height was represented by the average value of the maximum heights of the extracted portions obtained from these cross-sectional curves, where 10 cross-sectional curves were obtained from the sample film surface.

[0179] (8) Average particle diameter The average particle diameter in each layer was determined by observing 10 or more particles with a scanning electron microscope, measuring the particle diameters, and taking the average value. In this case, for non-spherical particles, the average value of the longest diameter and the shortest diameter was measured as the diameter of each particle.

[0180] (9) Particle content (particle concentration) of polyester layer A and polyester layer B In the polyester film (sample), a sample was scraped from the layer for which the particle concentration was to be measured, and after selecting a solvent that dissolves polyester but does not dissolve the particles and performing a dissolution treatment, the particles were centrifuged from the solution, and the ratio (ppm) with respect to the total mass of the particles was measured as the particle concentration.

[0181] (10) Intrinsic viscosity Approximately 0.25 g of the freeze - pulverized polyester film was dissolved in approximately 25 mL of a mixed solvent of phenol / 1,1,2,2 - tetrachloroethane (mass ratio 1 / 1) at 120 °C for 30 minutes so that the concentration became 1.00 g / dL. After cooling to 30 °C, the dropping seconds of only the sample solution and the solvent were measured at 30 °C with a fully automatic solution viscometer (manufactured by Sentech, "DT553"), and the intrinsic viscosity was calculated by the following formula (3). Intrinsic viscosity = ((1 + 4K H η SP ) 0.5 - 1) / (2K H C) ··· Formula (3) Here, η sp = η / η 0 - 1, where η is the dropping seconds of the sample solution, η 0 is the dropping seconds of only the solvent, C is the sample solution concentration (g / dL), and K H is the Huggins constant. K H was adopted as 0.33.

[0182] (11) Film haze In accordance with JIS K 7105:1981, the haze of the polyester film (sample) was measured with an integrating sphere turbidimeter NDH - 20D manufactured by Nippon Denshoku Industries Co., Ltd.

[0183]

Table 2

[0184] From the results of the above - mentioned examples and comparative examples, the polyester film contains titanium elements, and by filtering through a filter during melt extrusion, the number of aggregates (foreign substances) with a major axis of 1 μm or more and less than 3 μm in the film is suppressed to 350 pieces / cm 2 or less. Nevertheless, the number of protrusions with a maximum peak height (Sp) of 0.3 μm or more protruding from the film surface is 2.7 pieces / cm 2It can be suppressed as follows. As a result, for example, even if the miniaturization of the dry film resist progresses from the 5 μm level to 2 μm or less, it is possible to cope with it. Regarding the aggregated foreign matters in the film, the present invention has been achieved by utilizing the titanium catalytic activity to suppress the aggregation of the particles in the film and further combining a physical foreign matter removal method by filtration through a filter having a specific configuration.

Industrial Applicability

[0185] The polyester film of the present invention has the advantage that the generation of aggregates (foreign matters) such as particles and metals is reduced while maintaining the flatness, handleability, and winding characteristics of the film. Therefore, it can be applied to applications that extremely dislike the presence of foreign matters in the film, such as for forming dry film resists and manufacturing ceramic green sheets, and is an industrially valuable invention.

Claims

1. A polyester film containing particles having an average particle size of 0.03 to 0.80 μm, containing 3 ppm or less of antimony, containing 5 to 100 ppm of titanium, phosphorus and magnesium in total, and containing 350 or less foreign matter particles having a major axis of 1 μm or more and less than 3 μm in the film / cm2.

2. A film containing particles having an average particle size of 0.03 to 0.80 μm, the antimony content in the film is 3 ppm or less, the total content of titanium, phosphorus, and magnesium in the film is 5 to 100 ppm, and the number of protrusions protruding from the film surface with a maximum peak height (Sp) of 0.3 μm or more is 2.7 / cm ２ The following is a polyester film.

3. 2. The polyester film according to claim 1, which is a multi-layer film comprising a polyester layer B and a polyester layer A on at least one side of the polyester layer B.

4. 2. The polyester film according to claim 1, wherein the content of titanium element in the polyester film is 1 ppm or more and 30 ppm or less.

5. 2. The polyester film according to claim 1, wherein the content of phosphorus in the polyester film is 5 ppm or more and 35 ppm or less.

6. 2. The polyester film according to claim 1, wherein the content of magnesium element in the polyester film is 5 ppm or more and 35 ppm or less.

7. A polyester film containing particles having an average particle size of 0.03 to 0.80 μm, the antimony content in the film being 3 ppm or less, the total content of titanium, phosphorus and magnesium elements in the film being 5 to 100 ppm, the film being a multilayer film comprising a polyester layer B and a polyester layer A on at least one side thereof, all of the polyester layers constituting the multilayer film containing titanium elements.

8. A polyester film comprising particles having an average particle size of 0.03 to 0.80 μm, an antimony content of 3 ppm or less in the film, and a total content of titanium, phosphorus and magnesium elements in the film of 5 to 100 ppm, said film being a multilayer film comprising a polyester layer B and a polyester layer A on at least one side thereof, said polyester layer A 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.

9. The polyester film according to claim 3, wherein the particle content in the polyester layer A is in the range of 10 to 6,000 ppm.

10. A polyester film containing particles having an average particle size of 0.03 to 0.80 μm, the antimony content in the film being 3 ppm or less, and the total content of titanium, phosphorus, and magnesium elements in the film being 5 to 100 ppm, said film being a multilayer film comprising a polyester layer B and a polyester layer A on at least one side thereof, said polyester layer A containing two types of particles having different average particle sizes.

11. A polyester film comprising particles having an average particle size of 0.03 to 0.80 μm, an antimony content of 3 ppm or less in the film, and a total content of titanium, phosphorus and magnesium elements in the film of 5 to 100 ppm, said film being a multilayer film comprising a polyester layer B and a polyester layer A on at least one side thereof, said polyester layer A containing 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.

12. A polyester film comprising particles having an average particle size of 0.03 to 0.80 μm, an antimony content of 3 ppm or less in the film, and a total content of titanium, phosphorus and magnesium elements in the film of 5 to 100 ppm, the film being a multilayer film comprising a polyester layer B and a polyester layer A on at least one surface of the polyester layer B, and comprising another resin layer on at least one surface of the multilayer film.

13. A method for producing a polyester film according to any one of claims 1 to 12, comprising: a production step 1 in which a melt of polyester resin chips containing a titanium compound, which has been previously made into a master batch, is filtered through a filter medium containing a powdered sintered body and a filter medium containing a fibrous sintered body having a filtration accuracy of 5 μm or less; and a production step 2 in which a polyester film is produced using the polyester resin melt obtained in the production step 1.

14. The polyester film according to any one of claims 1 to 12, which is used for producing a dry film resist.

15. The polyester film according to any one of claims 1 to 12, which is used for producing a ceramic green sheet.

16. The polyester film according to any one of claims 1 to 12, which is used for forming an interlayer insulating layer.

17. The polyester film according to any one of claims 1 to 12, which is for optical use.

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