TW202340339A - Method for manufacturing polyester film,polyester film, dry film resist, and release film - Google Patents

Abstract

The present invention addresses the problem of providing a polyester film production method and a polyester film capable of suppressing optical defects when combined with a photosensitive resin layer or the like and used as a dry film resist. The present invention also addresses the problem of providing a dry film resist and a release film. A polyester film production method according to the present invention comprises: a step 1 in which a polyester resin precursor is continuously polymerized in the presence of a titanium compound, and after the antimony content determined by using inductively coupled plasma mass spectrometry to measure a product containing the produced polyester resin has dropped to 1.0 ppm by mass or less with respect to the product, a polyester resin is obtained; a step 2 in which a melt of the polyester resin is filtered by using a filter medium containing a powdery sintered body and a filter medium containing a fibrous sintered body having a filtration accuracy of 3 [mu]m or less; and a step 3 in which a polyester film is produced using the filtered melt.

Description

Manufacturing method of polyester film, polyester film, dry film photoresist and release film

The invention relates to a method for manufacturing a polyester film, a polyester film, a dry film photoresist and a release film.

Polyester films are produced by melt-extruding polyester resin to form a film, and then undergo processes such as heat treatment such as stretching and thermal relaxation. In recent years, polyester films have been given various functions by coating or affixing functional materials on the films, and are widely used as functional films. For example, a photosensitive composition may be used as a dry film photoresist by coating it as a functional material on a polyester film. On the other hand, in recent years, as the density of circuit wiring has increased, the dry film photoresist used to form the circuit wiring has been required to have higher resolution. In addition, the polyester film is also used to produce ceramic green sheets used in the manufacture of laminated ceramic condensers.

As an attempt to improve resolution, Patent Document 1 discloses a technology in which a support film including a resin layer containing microparticles is formed on one side of a biaxially stretched polyester film and the support film is formed with a resin layer containing microparticles. A photosensitive resin layer is layered on the opposite side of the resin layer.

Patent Document 1 discloses a photosensitive element that includes a support film and a photosensitive layer disposed on the support film. In this photosensitive element, the photosensitive layer contains a binder polymer and a photopolymerizable material having an ethylenically unsaturated bond. compound and photopolymerization initiator, and the number of defects with a diameter of 2 μm or more on the surface of the photosensitive layer side of the support film is 30 or less per 2 mm ² .

[Patent Document 1] International Publication No. 2018/100730

With the high resolution (refinement) of photoresist patterns in recent years, the support film constituting the dry film photoresist is usually patterned on the photosensitive resin layer through the support film. Therefore, in order to suppress failures caused by light scattering , the performance is reduced, and for transparency, higher performance than before is required. The present inventors referred to the technology described in Patent Document 1 and found that by using a dry film photoresist having a photosensitive composition on a polyester film, a fine photoresist pattern with a narrower pattern width (especially 7 μm or less) can be formed. As a result of the line and space (L/S) pattern), optical failures such as pinhole defects occur due to the characteristics of the polyester film. It is known that if an L/S wiring pattern is formed using a dry film photoresist that has suffered an optical failure, a wiring breakage failure occurs, and improvements are required. On the other hand, in recent years, with the increase in capacity and miniaturization of ceramic condensers, ceramic green sheets are required to be thinner and further thinned. As a result of research on ceramic green sheets, the inventors found that the properties of the polyester film used in manufacturing the ceramic green sheets may affect the performance of the ceramic green sheets.

In view of the above actual situation, the subject of the present invention is to provide a method for manufacturing a polyester film and a polyester film that can suppress optical failure when combined with a photosensitive resin layer and used as a dry film photoresist. Furthermore, an object of the present invention is to provide a polyester film manufacturing method and a polyester film that can suppress local unevenness defects when used for manufacturing ceramic green sheets. Furthermore, an object of the present invention is to provide a dry film photoresist and a release film.

As a result of diligent research on the above-mentioned problems, the present inventors found that the above-mentioned problems can be solved by the following structure.

[1] A method for manufacturing a polyester film, which includes: process 1, continuously polymerizing a polyester resin precursor in the presence of a titanium compound, and measuring the produced film by inductively coupled plasma mass spectrometry. After the antimony content of the polyester resin product is reduced to less than 1.0 ppm by mass relative to the above product, the polyester resin is obtained; Process 2 uses a filter material containing a powdery sintered body and a fibrous sinter containing a filtration accuracy of 3 μm or less The filter material is a filter material for filtering the melt of the polyester resin obtained in the process 1; and the process 3 is for manufacturing a polyester film using the melt filtered in the process 2. [2] The method for producing a polyester film according to [1], wherein before the polyester resin precursor is continuously polymerized, the reaction tank used for polymerization is cleaned. [3] The method for producing a polyester film according to [1] or [2], wherein the polyester film has a polyester base material that does not substantially contain inorganic particles. [4] The method for producing a polyester film according to any one of [1] to [3], wherein the polyester resin precursor contains a diol compound and a compound selected from the group consisting of a dicarboxylic acid and a dicarboxylic acid ester compound. Dicarboxylic acid compounds in the group. [5] The method for producing a polyester film according to any one of [1] to [4], wherein the polyester film contains at least one element selected from the group consisting of magnesium and phosphorus. [6] A polyester film having a haze of 0.6% or less, an antimony content measured by inductively coupled plasma mass spectrometry of 1 mass ppm or less, and a diameter of 9 to 9 when observed using a transmission polarizing microscope. The total number of 20μm foreign matter and voids is 10/ ^500mm2 or less. [7] The polyester film as described in [6], which is used for manufacturing dry film photoresist. [8] The polyester film according to [6] or [7], wherein the total number of foreign matter and voids with a diameter of 3 μm or more and less than 9 μm observed using a transmission polarizing microscope is 200/500mm ² or less. [9] A polyester film in which the total number of foreign matter and voids with a diameter of 9 to 20 μm observed under a transmission polarizing microscope is 1.7/ ^mm3 or less. [10] The polyester film according to [9], which is used for producing ceramic green sheets. [11] The polyester film according to [9] or [10], wherein the antimony content measured by inductively coupled plasma mass spectrometry is 1 mass ppm or less. [12] The polyester film according to any one of [9] to [11], wherein the total number of foreign matter and voids with a diameter of 3 μm or more and less than 9 μm observed using a transmission polarizing microscope is 1.7/mm ³ the following. [13] The polyester film according to any one of [6] to [12], which contains titanium, magnesium and phosphorus, and the content of titanium and the content of magnesium are measured by inductively coupled plasma mass spectrometry. The content and phosphorus content are respectively 1 to 100 ppm by mass relative to the total mass of the polyester film. [14] The polyester film according to any one of [6] to [13], which has a polyester base material that does not contain substantially inorganic particles. [15] The polyester film according to any one of [6] to [14], which has a polyester base material and a particle-containing layer. [16] The polyester film according to any one of [6] to [15], wherein the polyester film has a thickness of 1 to 35 μm. [17] The polyester film according to any one of [9] to [16], wherein the haze is 2.0% or less and the thickness is 1 to 35 μm. [18] A dry film photoresist having the polyester film described in any one of [6] to [17] and a photosensitive resin layer. [19] The dry film photoresist according to [18], wherein the photosensitive resin layer contains a binder polymer, a polymerizable compound having an ethylenically unsaturated bond, and a photopolymerization initiator. [20] A release film including the polyester film according to any one of [6] to [17] and a release layer. [Effects of the invention]

According to the present invention, it is possible to provide a method for manufacturing a polyester film that can suppress optical failure when used as a dry film photoresist in combination with a photosensitive resin layer, and a polyester film. Furthermore, according to the present invention, it is possible to provide a method for producing a polyester film and a polyester film that can suppress local unevenness defects when used for producing ceramic green sheets. Furthermore, according to the present invention, a dry film photoresist and a release film can be provided.

Hereinafter, embodiments of the present invention will be described in detail. In addition, the present invention is not limited to the following embodiments at all, and can be implemented with appropriate modifications within the scope of the purpose of the present invention.

In this specification, the numerical range expressed using "～" means a range including the numerical values described before and after "～" as the minimum value and the maximum value respectively. Within the numerical ranges described in stages in this specification, the upper limit or lower limit described in a certain numerical range may be replaced by the upper limit or lower limit of other numerical ranges described in stages. In addition, within the numerical range described in this specification, the upper limit value or the lower limit value described in a certain numerical range may be replaced by the value shown in the Example.

In this specification, a combination of two or more preferred aspects is a more preferred aspect. In this specification, when there are multiple substances corresponding to each component in the composition or layer, unless otherwise specified, the amount of each component in the composition or layer refers to the amount present in the composition or layer. The total amount of the above-mentioned plural substances. In this specification, the term "process" includes not only an independent process but also a process that can achieve the expected purpose of the process even if it cannot be clearly distinguished from other processes. In this specification, the "longitudinal direction" refers to the longitudinal direction of the film during production, and has the same meaning as the "conveying direction" and the "machine direction". In this specification, the "width direction" refers to the direction orthogonal to the longitudinal direction. In this disclosure, "orthogonal" is not limited to strict orthogonality but includes approximately orthogonality. "Approximately orthogonal" means intersecting at 90°±5°, preferably 90°±3°, and even more preferably 90°±1°. In addition, the "film width" means the distance between both ends in the width direction of the film.

In this specification, "(meth)acrylic acid" is a general term for acrylic acid and methacrylic acid, and refers to "one or more types of acrylic acid and methacrylic acid". Similarly, "(meth)acrylate" means "one or more types of acrylate and methacrylate", and "(meth)acrylic acid" means "one or more type of acrylic acid and methacrylic acid".

In this specification, "exposure" includes not only exposure using light but also drawing using particle beams such as electron beams and ion beams, unless otherwise specified. Examples of the light used for exposure include actinic rays (active energy rays) such as far ultraviolet rays, extreme ultraviolet rays (EUV light), X-rays, and electron beams represented by the bright line spectrum of mercury lamps and excimer lasers. ). In this specification, unless otherwise specified, the refractive index refers to the refractive index with respect to light with a wavelength of 550 nm measured using an Abbe refractometer ("NAR-2T" manufactured by ATAGO CO., LTD.).

In this specification, unless otherwise specified, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are molecular weights obtained by using TSKgel GMHxL, TSKgel G4000HxL, TSKgel G2000HxL and/or TSKgel Super HZM-N (both trade names manufactured by TOSOH CORPORATION) is a gel permeation chromatography (GPC: Gel Permeation Chromatography) analysis device that uses THF (tetrahydrofuran) as a solvent and detects it with a differential refractometer. , and use polystyrene as the standard material to convert the molecular weight.

[First Embodiment: Manufacturing Method of Polyester Film] The method for producing a polyester film according to the first embodiment of the present invention (hereinafter also referred to as “this production method”) is characterized by including: Process 1, in which a polyester resin precursor is continuously performed in the presence of a titanium compound. Polymerization of a substance, and obtaining a polyester resin after the content of antimony obtained by measuring a product containing the produced polyester resin by inductively coupled plasma mass spectrometry is reduced to less than 1.0 mass ppm relative to the product; Process 2, using a product containing A filter material of a powdery sintered body and a filter material containing a fibrous sintered body with a filtration accuracy of 3 μm or less, filtering the melt of the polyester resin obtained in the process 1; and process 3, using the melt filtered in the process 2 Made of polyester film.

By this manufacturing method including the above-mentioned processes 1 to 3, it is possible to produce an optical failure suppressing effect (hereinafter also referred to as "optical failure suppressing effect") when combined with a photosensitive resin layer and used as a dry film photoresist. Although the details of the cause of the polyester film are not clear yet, the present inventors roughly infer as follows. If there are any foreign matter or voids in the polyester film used in dry film photoresist, only that part cannot be exposed, so it is considered that an optical failure has occurred. For example, when the photosensitive composition contained in the photosensitive resin layer or the like in the dry film resist is a negative photosensitive composition, if the photosensitive resin layer or the like is exposed through the polyester film, the The photosensitive resin layer corresponding to any of the foreign matter and voids in the polyester film does not undergo a photocuring reaction, and the photosensitive composition contained in the exposed area is removed in the subsequent development process. This results in the formation of pinholes that become optical failures. Therefore, the present inventors confirmed the details of the foreign matter and voids present in this polyester film, and discovered the foreign matter present in the polyester film, colored foreign matter in the voids, and transparent particles with a diameter of 9 to 20 μm. Foreign matter and voids have a great influence on optical failure when exposing a photosensitive resin layer etc. to ultraviolet light. As a result of further analysis of each foreign matter by the present inventors, it was found that the colored foreign matter contains components derived from antimony, and that the transparent foreign matter is caused by gel generated during the polymerization of polyester resin or by the reaction between magnesium and phosphorus. product. Furthermore, it is known that the above-mentioned voids are generated around foreign matter such as colored foreign matter and transparent foreign matter. It is presumed that in the method for manufacturing a polyester film of this embodiment, the polyester resin in which the antimony content is sufficiently reduced is supplied, and the melt of the supplied polyester resin is filtered using a combination of specific filter materials. The above-mentioned foreign matter and voids contained in the polyester resin used as the raw material of the polyester film can be suppressed, so optical failure of the dry film photoresist can be suppressed.

Furthermore, by having the above-mentioned processes 1 to 3 in this manufacturing method, when the produced polyester film is used to produce a ceramic green sheet, the effect of suppressing local concave defects (hereinafter also referred to as "concave defects") can be exerted in the produced ceramic green sheets. Although the details of the reason are not yet clear, the present inventors roughly infer as follows. It is presumed that in the method for manufacturing a polyester film of this embodiment, the polyester resin in which the antimony content is sufficiently reduced is supplied, and the melt of the supplied polyester resin is filtered using a combination of specific filter materials. The above-mentioned foreign matter and voids contained in the polyester resin used as the raw material of the polyester film can be suppressed. As a result, it is presumed that a polyester film having few convex portions on the surface can be produced, and the occurrence of local concave defects can be further suppressed in a ceramic green sheet produced using such a polyester film. Hereinafter, the "effect of the present invention" refers to at least one of the optical failure suppressing effect and the concavity defect suppressing effect exerted by each embodiment of the present invention.

Each process of this manufacturing method is demonstrated below, referring to the figure which shows an example of the manufacturing apparatus of a polyester film. FIG. 1 is a schematic diagram showing an example of the structure of a polyester film manufacturing apparatus used in the present manufacturing method. The film manufacturing apparatus 10 shown in FIG. 1 includes a reaction tank 12, a film forming process section 14, a longitudinal stretching process section 16, a transverse stretching process section 18 for transverse stretching, and a winding section 20.

Regarding the reaction tank 12, a polyester resin precursor is polymerized to produce polyester resin. The film forming process unit 14 is equipped with an extruder 24, a pipe 34, a filter 36, a pipe 38, a mold 26, and a casting drum 28. The polyester resin produced in the reaction tank 12 is heated and melted, and the obtained melt is Filter, and use the filtered melt to produce polyester film F. The longitudinal stretching process section 16 is provided with a pair of low-speed rollers 30 and a pair of high-speed rollers 32, and stretches the polyester film F produced by the film forming process section 14 in the longitudinal direction. The transverse stretching process part 18 stretches the polyester film F stretched in the longitudinal direction in the transverse direction. The winding part 20 winds the polyester film F stretched in the transverse direction.

[Process 1] Process 1 is performed: in the reaction tank 12, the polyester resin precursor is continuously polymerized in the presence of the titanium compound to produce a polyester resin with an antimony content below a predetermined value.

As the reaction vessel used in Process 1, a well-known reaction vessel used in the synthesis of polyester resin can be used, and can be appropriately selected according to the type and amount of the polyester resin and its precursor. In Process 1, from the viewpoint of more excellent effects of the present invention, it is better to use a reaction tank that has been cleaned beforehand. The cleaning method of the reaction tank is not particularly limited. Examples include cleaning the liquid contact part of the reaction tank (the part where the polyester resin precursor and the polyester resin come into contact) with a cleaning solution, and using polishing. Grinding treatment such as agent and dry ice blasting. Examples of the cleaning liquid include organic solvents such as ethylene glycol and triethylene glycol, water or aqueous solutions, acids or alkalis, and combinations thereof, and are appropriately selected depending on the polyester resin and its precursor. Among them, as a cleaning process of the reaction tank, from the viewpoint of the effect of the present invention being more excellent, it is preferable to perform a process of heating and cleaning by using an organic solvent such as ethylene glycol and triethylene glycol. Finally, the liquid-contacting part of the reaction tank is subjected to polishing and other grinding processes to physically remove the stacked materials. The polishing method is not particularly limited and can be performed by known methods. The cleaning process of the reaction tank must be carried out before the process 1 of continuously polymerizing the polyester resin. The timing of performing the cleaning process is not particularly limited. However, for example, process 1 can be appropriately interrupted to clean the reaction tank depending on the composition of the polyester resin produced in process 1 (more specifically, the antimony content described below, etc.).

In process 1, in the above-mentioned cleaned reaction tank, the polyester resin precursor is continuously polymerized in the presence of the titanium compound to produce the polyester resin. However, the polyester resin produced only after the content of antimony contained in the product containing the polyester resin produced by the continuous polymerization falls below a predetermined value is supplied to the process 2 described below. Here, "continuously polymerize the polyester resin precursor" means that the polyester resin precursor is continuously or intermittently supplied into the reaction tank, and the reactant is polymerized while being transferred in the reaction tank (polycondensation reaction). ), a series of processes in which the obtained polymer is continuously or intermittently discharged from the reaction tank. The content of antimony contained in the above products was measured by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). More specific measurement methods are described in the Examples described later. In this production method, when the antimony content measured by the ICP-MS method satisfies the condition of 1.0 mass ppm or less relative to the above-mentioned product, the produced polyester resin is supplied to Process 2. From the viewpoint that the effect of the present invention is more excellent, the conditions for the antimony content of the polyester resin supplied to the process 2 are preferably 0.8 mass ppm or less, more preferably 0.7 mass ppm or less, and 0.6 mass ppm or less relative to the above-mentioned product. For further improvement. The lower limit value is not particularly limited and may be 0 ppm by mass.

The titanium compound used in Process 1 is a compound containing titanium, and examples thereof include known titanium compounds that can be used as catalysts in the polymerization of polyester resin precursors. As the titanium compound, an organic titanium compound is preferred, and an organic chelated titanium complex is more preferred. An organic chelated titanium complex is a titanium compound having an organic acid or a salt thereof as a ligand. Examples of organic acids include citric acid, lactic acid, trimellitic acid, and malic acid. Among them, an organic chelated titanium complex having citric acid or citrate as a ligand is further preferred. As the titanium compound, those described in paragraphs 0049 to 0053 of Japanese Patent No. 5575671 can also be used, and this description is incorporated into this specification.

The added amount of the titanium compound used in Process 1 is preferably 1 to 500 ppm by mass relative to the total mass of the polyester resin precursor in terms of the converted value of titanium element, and is preferably 1 to 100 ppm by mass. More preferably, the amount is 1 to 30 ppm by mass, the amount is 3 to 20 ppm by mass, and the amount of 5 to 15 ppm by mass is most preferred.

In the polymerization of the polyester resin precursor in Process 1, compounds other than the titanium compound may be present together with the above-mentioned titanium compound. Examples of the other compounds include alkali metal compounds (for example, potassium compounds, sodium compounds), alkaline earth metal compounds (for example, calcium compounds, magnesium compounds), zinc compounds, lead compounds, manganese compounds, cobalt compounds, and aluminum compounds. compounds, antimony compounds, germanium compounds and phosphorus compounds. As the above-mentioned other compound, at least one compound selected from the group including a magnesium compound and a phosphorus compound is preferred, and it is more preferred to use both a magnesium compound and a phosphorus compound.

Examples of magnesium compounds include magnesium oxide, magnesium hydroxide, and magnesium salts such as magnesium alkoxide, magnesium acetate, and magnesium carbonate. Among these, magnesium acetate is preferable from the viewpoint of solubility in ethylene glycol. Examples of the phosphorus compound include phosphate esters, and pentavalent phosphate esters that do not have an aromatic ring as a substituent are preferred. Examples of the phosphate ester include trimethyl phosphate, triethyl phosphate, tri-n-butyl phosphate, trioctyl phosphate, tris(triethylene glycol) phosphate, acid methyl phosphate, and acid phosphoric acid. Ethyl ester, isopropyl acid phosphate, butyl acid phosphate, monobutyl phosphate, dibutyl phosphate, dioctyl phosphate and triethylene glycol acid phosphate, trimethyl phosphate or triethyl phosphate are the more good.

The addition amount of the above-mentioned other compounds is preferably 3 to 500 ppm by mass, and more preferably 5 to 100 ppm by mass relative to the total mass of the polyester resin precursor in terms of converted values for metal elements or phosphorus elements. good. In the case of using a magnesium compound, from the viewpoint of being able to impart high electrostatic application properties to the polyester film, the added amount of the magnesium compound is 50% based on the total mass of the polyester resin precursor in terms of the magnesium element conversion value. The amount of mass ppm or more is preferred, the amount of 50 to 100 mass ppm is even more preferred, the amount of 60 to 90 mass ppm is further preferred, and the amount of 70 to 80 mass ppm is particularly preferred. In addition, when using a phosphorus compound, the added amount of the phosphorus compound is preferably 50 to 90 ppm by mass relative to the total mass of the polyester resin precursor in terms of the converted value of the phosphorus element, and is preferably 60 to 80 ppm. The amount of ppm by mass is more preferable, and the amount of 65 to 75 ppm by mass is still more preferable.

Regarding the content of titanium contained in the polyester resin precursor, as well as elements other than titanium such as magnesium and phosphorus, the polyester resin is measured according to a method for measuring the content of antimony contained in the product based on the ICP-MS method. obtained from precursors or products.

The polyester resin precursor used in Process 1 and the polyester resin produced in Process 1 will be described in detail in the polyester film of the second embodiment.

The reaction conditions when polymerizing the polyester resin precursor to produce the polyester resin through process 1 are not particularly limited, as long as they are appropriately set according to the type of the polyester resin precursor. The reaction temperature in process 1 is preferably 260-300°C, and more preferably 275-285°C. The pressure in the reaction tank in process 1 is preferably 1.33×10 ^-3 to 1.33×10 ^-5 MPa, and more preferably 6.67×10 ^-4 to 6.67×10 ^-5 MPa.

As a synthesis method of the polyester resin, methods described in [0033] to [0070] of Japanese Patent No. 5575671 can also be used, and the contents of the above publications are incorporated into this specification.

[Process 2] In Process 2, a filter material containing a powdery sintered body and a filter material containing a fibrous sintered body with a filtration accuracy of 3 μm or less (hereinafter also referred to as "specific fibrous sintered body") are used to filter the filter material obtained in Process 1. The polyester resin melt is filtered. In the film production apparatus 10 shown in FIG. 1 , the process 2 is implemented by the extruder 24 and the filter device 36 of the film production process unit 14 .

The polyester resin obtained in the process 2 may be heated and dried before being heated and melted by the extruder 24. In particular, when the polyester resin contains an aromatic polyester resin, the produced polyester resin may be heated and dried. After the polyester resin is heated and dried, it is preferred to heat and melt it. The heating temperature for the above-mentioned heat drying is usually 80 to 180°C for 12 to 36 hours. In particular, when the heating temperature is lower than the glass transition temperature of the polyester resin, drying is preferably performed in a reduced pressure environment.

Polyester resin is melt-mixed in an extruder. The conditions for melt mixing using an extruder are not particularly limited as long as a melt of polyester resin is produced. Regarding the temperature inside the extruder, it is preheated to [Tm+10°C] to [Tm+70°C] (preferably [Tm+20°C] to [Tm+50°C]) before supplying the polyester resin. Better. "Tm" refers to the melting point of the polyester resin. The melting and mixing time of the polyester resin is usually 3 minutes or more, preferably 3 to 20 minutes. The melt of the polyester resin thus obtained is supplied to the filter device 36 through the pipe 34 .

The molten material melted by the extruder 24 is filtered using a filter device 36 having a filter material containing a powdery sintered body and a filter material containing a specific fibrous sintered body. By filtering the melt using the filtration device 36, garbage, unreacted materials, gels, foreign matter thermally degraded during the melting process, etc. contained in the melt of the polyester resin are removed.

The filter device 36 is a fibrous sintered body using sintered fibers, and has a filter medium including a specific fibrous sintered body with a filtration accuracy of 3 μm or less and a filter medium including a powdery sintered body using sintered powder. By performing filtration using both a filter material containing a specific fibrous sintered body and a filter material containing a powdery sintered body, the gel contained in the polyester resin, which is one of the causes of optical failure, can be removed, so it is presumed that it can be produced A polyester film that further suppresses optical failure when used in combination with a photosensitive resin layer and used as a dry film photoresist.

Regarding the filter device used in Process 2, as long as it has a filter material containing a specific fibrous sintered body and a filter material containing a powdery sintered body, and has a structure in which the melt of the polyester resin and the filter materials are both in contact, the specific structure does not matter. No special restrictions. Examples of the filtration device include a filter device including at least one integrated filter containing a specific fibrous sintered body and a powdery sintered body as a filter material, and a filter device including at least one of the specific fibrous sintered body in combination. and a filter device including at least one filter of the powdery sintered body. When a filter containing a specific fibrous sintered body and a filter containing a powdery sintered body are used together, the arrangement of the two is not particularly limited as long as the molten material is in contact with both. Among them, a filter device including at least one filter integrating a specific fibrous sintered body and a powdery sintered body is preferred. Moreover, as a filter including the above-mentioned filter material, a leaf disk type filter is preferable. The number and size of filters including the above filter materials are appropriately selected based on the type of polyester resin, characteristics such as viscosity, and conditions such as flow rate.

From the viewpoint of obtaining a polyester membrane with a more excellent effect of the present invention by removing foreign matter having a diameter of 9 to 20 μm, etc., it is preferable that the filtration precision of the filter material including the specific fibrous sintered body is 2 μm or less. The lower limit is not particularly limited, but is, for example, 1 μm. Here, filtration accuracy is defined as "the smallest glass bead diameter that can capture more than 95% through its filter material." The lower the value of filtration precision, the higher the precision of the filter material.

FIG. 2 is a schematic cross-sectional view showing an example of the structure of a filter device used for filtering the polyester resin melt in Process 2. The filter device 36 shown in FIG. 2 is composed of a cylindrical housing 44 and a plurality of disc-shaped filters 46 disposed in the housing 44. Furthermore, the casing 44 has a supply port 40 connected to the pipe 34 to supply the melt of the polyester resin, and a discharge port 42 connected to the pipe 38 to discharge the filtered melt. In the filtration device 36 , a plurality of filters 46 are arranged at predetermined intervals via spacers 54 along the axial direction of the flow path 48 .

FIG. 3 is a schematic diagram showing an example of the structure of a filter included in the filtration device. The disc-shaped filter 46 shown in FIG. 3 has a structure in which a substantially disc-shaped sintered body having a through hole in the center is sandwiched between a substantially disc-shaped porous plate 53 having a through hole in the center. 52. Install the annular ring member 50 in the central through hole. The sintered body 52 includes a specific fibrous sintered body and a powdery sintered body. The side wall of the ring member 50 is provided with a plurality of through holes 51 arranged along the circumferential direction, which serve as flow paths for the melt filtered by the sintered body 52 . The diameter of the through hole 51 is, for example, 1 to 3 μm or less. The through hole 51 communicates with the flow path 48 in which one end is closed and the other end communicates with the discharge port 42 . The diameter D of the filter 46 is appropriately set depending on the supply amount and residence time of the melt from the extruder 24 .

As shown by the arrow in FIG. 2 , the melt of the polyester resin heated and melted by the extruder 24 is supplied from the pipe 34 through the supply port 40 into the casing 44 of the filter device 36 . The molten material supplied into the housing 44 flows radially outward of the filter through the member 56 and then flows into the disc-shaped filter 46 and is filtered by the sintered body 52 to remove foreign matter and the like. The molten material that has passed through the sintered body 52 reaches the flow path 48 through the through hole 51 of the ring member 50 , flows from the open end of the flow path 48 through the discharge port 42 into the pipe 38 , and is supplied from the pipe 38 to the mold 26 .

The filtration conditions when filtering the melt with the filtration device are not particularly limited, but in order to effectively remove foreign matter and the like, it is preferable to set the filtration pressure in the range of 10 to 200 kg/cm ² and perform the filtration process. Furthermore, the residence time of the molten material remaining in the filtering device 36 is preferably from 1 minute to 30 minutes. Furthermore, it is preferable to change the melting temperature and discharge amount of the polyester resin so that the apparent viscosity of the melt at the input port of the filter device 36 becomes 10 to 2000 Pa·s.

It is best to clean the filter of the filtration device after use. By cleaning after use, the filter can be reused. Examples of cleaning methods include those described in Japanese Patent Application Laid-Open No. 2019-013890 and Japanese Patent Application Laid-Open No. 2008-037012, and these contents are incorporated into this specification. Furthermore, the filter device used for filtering the polyester resin melt in Process 2 is not limited to the above-mentioned filter device.

[Process 3] In Process 3, a polyester film is produced using the melt of the polyester resin filtered in Process 2. In the film manufacturing apparatus 10 shown in FIG. 1 , the process 3 is implemented using the mold 26 and the casting drum 28 of the film forming process section 14 , the longitudinal stretching process section 16 and the transverse stretching process section 18 .

First, the melt of the polyester resin filtered in the process 2 is extruded into a film shape through the die 26, and an unstretched polyester film (hereinafter, also referred to as Polyester film is referred to as "film F".). The temperature of the melt supplied to the mold 26 is heated to, for example, [Tm+10°C] to [Tm+70°C], and is cooled and solidified on the casting drum 28 at 30 to 110°C to become the unstretched film F (non-stretched film F). wafer). The melt can be extruded in a single layer or in multiple layers. In addition, as an extruder for extruding the molten material, a known extruder can be used.

Next, the unstretched film F is stretched (longitudinal stretching) in the longitudinal direction (longitudinal direction) by a pair of low-speed rollers 30 and a pair of high-speed rollers 32 provided in the longitudinal stretching process section 16 . When stretching in the longitudinal direction, the film F is preferably heated to a temperature of [Tg+5°C] to [Tg+60°C] (Tg: glass transition temperature of polyester resin). The stretching ratio in the longitudinal direction (length direction) based on longitudinal stretching is, for example, 2 to 7 times, and preferably 2 to 5 times.

Thereafter, the longitudinally stretched film F is stretched (transversely stretched) in the transverse direction (film width direction) by the transverse stretching process unit 18 to produce a biaxially stretched film (biaxially oriented film) . In the transverse stretching process section 18, hot air is sent to the film F, and both ends in the width direction of the film F are heated while being held by the tenter. The heating temperature of the film F during transverse stretching is, for example, [Tg+5°C] to [Tg+60°C], and preferably [Tg+20°C] to [Tg+50°C]. The stretch ratio in the transverse direction (longitudinal direction) based on transverse stretching is, for example, 2 to 7 times, and preferably 2 to 5 times.

The thus biaxially stretched film F is wound by the winding unit 20 after final cooling. Regarding the temperature of the stretching process, when the polyester resin is polyethylene terephthalate (PET), 120 to 150°C is preferred, and when the polyester resin is polyethylene terephthalate (PEN) In this case, 140~180℃ is better. Furthermore, by winding the longitudinally stretched film F by the winding section 20 without passing through the transverse stretching process section 18, it is possible to produce a uniaxially stretched film that is stretched only in the longitudinal direction. Regarding process 3, you can refer to the description contents of [0113] to [0169] of International Publication No. 2020/241692, which contents are incorporated into the specification of this application.

The polyester film produced by this production method may have a single-layer structure including only a polyester base material formed from the melt of the polyester resin filtered in the process 2, or may have a polyester base material formed by the filtered polyester resin used in the process 2. A multilayer structure consisting of a polyester base material formed from a melt of polyester resin and a particle-containing layer containing particles.

It is preferred that the polyester base material of the polyester film contains substantially no inorganic particles, and it is even more preferred that the polyester base material contains substantially no particles. In addition, "substantially does not contain" the above-mentioned particles is defined as follows: when the elements derived from the above-mentioned particles are quantitatively analyzed by fluorescence X-ray analysis with respect to the thermoplastic base material, the content of the above-mentioned particles is relative to the thermoplastic base material. The total mass of the material is less than 50 ppm by mass. The content of the above-mentioned particles contained in the thermoplastic base material is more preferably 10 mass ppm or less relative to the total mass of the thermoplastic base material, and is particularly preferably less than the detection limit. Even if the above-mentioned particles are not actively added to the polyester base material, contaminants, raw material resins, or stains attached to the production lines or equipment in the above-mentioned manufacturing process will be peeled off and mixed into the polyester base material. For example, it is better to remove unintentionally mixed particles through filtration in the above-mentioned process 2.

＜Particle-containing layer formation process (Process 4)＞ A polyester film having a polyester base material and a particle-containing layer can be produced by performing a particle-containing layer forming process (process 4) for forming a particle-containing layer at any stage of this production method. As the process 4, for example, there can be mentioned a process in which a particle-containing layer-forming composition containing particles and a resin (hereinafter also referred to as "composition A") is formed by in-line coating. The coating film of composition A is dried as necessary to form a particle-containing layer. Examples of the polyester base material to which composition A is coated in process 4 include unstretched polyester base material and uniaxially stretched polyester base material. Uniaxially stretched polyester base material For better. That is, it is preferable to perform process 4 between the longitudinal stretching and transverse stretching in process 3. This is because by simultaneously stretching the uniaxially stretched polyester base material and the particle-containing layer laterally, the adhesion between the polyester base material and the particle-containing layer can be improved.

Composition A can be prepared by mixing particles contained in the particle-containing layer, resin, additives if necessary, and a solvent. Examples of the solvent include water, ethanol, toluene, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, and propylene glycol monoethyl ether. Among them, water is preferable from the viewpoint of environment, safety and economy. Composition A may contain a single solvent or two or more solvents. The content of the solvent is preferably 80 to 99% by mass relative to the total mass of composition A. That is, the total content of components other than the solvent (solid content) is preferably 0.5 to 20% by mass relative to the total mass of composition A.

Preferable aspects including the particles, resin, and additives contained in the composition A are the same as those described in the particle-containing layer of the polyester film of the second embodiment described below.

The process 4 for forming the particle-containing layer is not limited to the process formed by coating the above-mentioned composition A on the polyester substrate. For example, it can be formed by using the melt filtered in the process 2 and containing it. A polyester film is produced by co-extruding a melt of particles and resin in the particle-containing layer to form a laminated body in which the polyester base material and the particle-containing layer are laminated. The laminated body is then biaxially stretched.

The polyester film produced by the production method described above exhibits the effect of suppressing optical failure when combined with a photosensitive resin layer and the like and used as a dry film photoresist. The preferred aspects, uses, etc. of the polyester film produced by this manufacturing method are the same as the preferred aspects, uses, etc. of the polyester film of the following 2nd Embodiment and 3rd Embodiment.

[Second Embodiment: Polyester Film (1)] A polyester film according to the second embodiment of the present invention is characterized by a haze of 0.6% or less and an antimony content measured by an ICP-MS method. It is less than 1 ppm by mass, and the number of foreign matter and voids with a diameter of 9 to 20 μm observed using a transmission polarizing microscope is less than 10/500mm ² .

Although the details of the reason why the polyester film of this embodiment exhibits the optical failure suppressing effect because it has the above-mentioned structure are not yet clear, the present inventors roughly infer as follows. As described above, the inventors of the present invention studied the foreign matter and voids present in the polyester film, which are considered to be the cause of optical failure in dry film photoresists, and found that the foreign matter and voids contained in the above-mentioned foreign matter and voids originate from antimony. The components of colored foreign matter, as well as transparent foreign matter and voids (holes) with a diameter of 9 to 20 μm have a great impact on optical failure when the photosensitive resin layer, etc. is exposed to ultraviolet light. It is presumed that in the polyester film of this embodiment, the occurrence of the above-mentioned colored foreign matter is suppressed by setting the antimony content to a predetermined value or less, and by reducing the content of foreign matter and voids with a diameter of 9 to 20 μm to a predetermined value. The optical failure of dry film photoresist can be suppressed below the value.

[Characteristics of polyester film] ＜Content of antimony＞ The content of antimony (Sb) contained in the polyester film of this embodiment is 1 mass ppm or less based on the total mass of the polyester film. From the viewpoint of more excellent effects of the present invention, the antimony content is preferably 0.7 mass ppm or less, more preferably 0.6 mass ppm or less, and further preferably 0.5 mass ppm or less relative to the total mass of the polyester film. The lower limit value is not particularly limited and may be 0 ppm by mass. The amount of antimony contained in the polyester film can be measured by ICP-MS. Details of the measurement method are described in the Examples described later.

<The total number of foreign matter and voids> In the polyester film of this embodiment, the total number of foreign matter and voids with a diameter of 9 to 20 μm observed using a polarizing microscope is 10/500mm ² or less. The unit of “pieces/500mm ² ” mentioned above refers to the number of foreign matter or voids per 500mm ² observation area of the polyester film observed using a polarizing microscope. The total number of foreign matter and voids with a diameter of 9 to 20 μm contained in the polyester film, and the total number of foreign matter and voids with a diameter of 3 μm or more and less than 9 μm, as described below, were measured using a transmission polarizing microscope. By using a transmission-type polarizing microscope with a polarizing lens, it is possible to observe changes in color shades (refractive index changes) of resin around foreign matter or voids, and to count foreign matter and voids present inside the film with high accuracy. The method for measuring the total number of foreign matter and voids in the polyester film is described in detail in the Examples described below.

From the viewpoint of a better optical failure suppression effect, it is preferable that the total number of foreign matter and voids with a diameter of 9 to 20 μm observed using a polarizing microscope is smaller, and 7/ ^500mm2 or less is preferable. Furthermore, the lower limit of the total number of foreign matter and voids with a diameter of less than 9 to 20 μm is not particularly limited, and may be 0/500mm ² .

Examples of the foreign matter with a diameter of 9 to 20 μm contained in the polyester film include transparent foreign matters including gel generated during the polymerization of the polyester resin and thermally degraded polyester generated by the polymerization. , and foreign substances caused by any of antimony compounds, magnesium compounds, phosphorus compounds, and titanium compounds (for example, phosphates generated in the reaction of magnesium compounds and phosphorus compounds as additives). Examples of voids with a diameter of 9 to 20 μm contained in the polyester film include voids generated around the foreign matter described above. Regarding the substances constituting foreign matter contained in the polyester film, SEM-EDX (Scanning Electron Microscope)-Energy dispersive X-ray analysis (Energy dispersive X-ray) of the cross section of the foreign matter contained in the polyester film can be performed ray spectrometry)) measurement for analysis.

From the viewpoint of a more excellent optical failure suppression effect, the total number of foreign matter and voids with diameters of 3 μm or more and less than 9 μm observed on the polyester film of this embodiment using a polarizing microscope is preferably 200/500mm ² or less, and 150 is preferred. /500mm ² or less is better, 100 pcs/500mm ² or less is even better, 70 pcs/500mm ² or less is particularly good. The lower limit of the total number of foreign matter and voids with a diameter of 3 μm or more and less than 9 μm is not particularly limited, but may be 0/500mm ² .

Examples of the foreign matter and voids with a diameter of 3 μm or more and less than 9 μm contained in the polyester film include transparent foreign matters including gel generated during polymerization of the polyester resin, and components derived from Sb. Colored foreign matter and phosphate generated by the reaction of magnesium compound and phosphorus compound as additives, as well as voids generated around foreign matter such as colored foreign matter and transparent foreign matter.

In addition, when observing the polyester film of this embodiment using a polarizing microscope, the total number of foreign matter and voids exceeding 20 μm in diameter is preferably less than 1/500mm ² , and more preferably 0/500mm ² (that is, not observed). .

＜Haze＞ The haze of the polyester film of this embodiment is 0.6% or less. From the viewpoint of more excellent transparency and optical failure suppression performance, the haze of the polyester film is preferably 0.5% or less, more preferably 0.4% or less, and further preferably less than 0.3%. The lower limit value is not particularly limited, but 0% or more is preferred. The haze of the polyester film can be measured using a known haze meter (for example, "NDH-2000" manufactured by NIPPON DENSHOKU INDUSTRIES Co., Ltd., etc.) in accordance with JIS K 7105.

[Structure] The polyester film of this embodiment may have a single-layer structure including only a polyester base material formed using a melt of polyester resin, or may have a polyester base material formed using a melt of polyester resin and a film containing particles. Particles contain a multi-layered structure of layers. When the polyester film of this embodiment has a particle-containing layer, one particle-containing layer may be disposed on one side of the polyester base material, or two particle-containing layers may be disposed on both sides of the polyester base material. Among them, it is preferable to arrange one particle-containing layer on one side of the polyester base material. The polyester film of this embodiment may have a polyester base material and other layers besides the particle-containing layer. Examples of such other layers include an adhesive layer, a peeling layer, an antistatic layer, and an oligomer precipitation preventing layer. Furthermore, an intermediate layer such as a primer layer may be provided between the polyester base material and the particle-containing layer. The thickness of these other layers is preferably 1 nm to 1 μm, and more preferably 30 to 500 nm.

＜Polyester base material＞ The polyester base material is a film-like object containing polyester resin as a main component. Here, "main component" refers to the component with the largest content (mass) among all components contained in an object. The polyester base material may contain a single type of polyester resin, or may contain two or more polyester resins.

It is preferable that the polyester base material of the polyester film of this embodiment contains substantially no inorganic particles. That is, regarding the polyester base material, when the elements derived from the above-mentioned inorganic particles are quantitatively analyzed by fluorescence X-ray analysis, the content of the above-mentioned inorganic particles is 50 mass ppm or less relative to the total mass of the polyester base material. Better. Here, examples of inorganic particles include inorganic particles contained in a particle-containing layer described below. It is more preferable that the content of the above-mentioned particles contained in the polyester base material is 10 mass ppm or less relative to the total mass of the polyester base material, and it is further more preferable that it is less than the detection limit.

＜＜Polyester resin＞＞ As the polyester resin, aromatic polyester resin is preferred from the viewpoint of excellent dimensional stability, mechanical strength, and transparency. Examples of aromatic polyester resins include polyethylene terephthalate and polyethylene-2,6-naphthalenedicarboxylate.

Typical examples of aromatic polyesters include polyesters whose main monomer units include ethylene terephthalate or ethylene 2,6-naphthalate (that is, polyethylene terephthalate (polyethylene terephthalate)). PET) or polyethylene-2,6-naphthalate (PEN)) and polyesters (copolymers) containing the two monomer units of ethylene terephthalate and ethylene-2,6-naphthalate ). The aromatic polyester is an aromatic polyester having repeating units containing 0 to 40 mol% of ethylene terephthalate units and 60 to 100 mol% of ethylene 2,6-naphthalate units. Ester is preferred. In addition, the ultimate viscosity of the aromatic polyester is preferably in the range of 0.50 to 0.80. If the ultimate viscosity is 0.50 or more, the film is less likely to break even if the stretching ratio is increased, and whitening is less likely to occur even if the film is stretched strongly. On the other hand, if the intrinsic viscosity is 0.80 or less, there is no need to significantly increase the molecular weight, so the load in the melt polymerization and solid phase polymerization processes is small, which is preferable from the viewpoint of productivity.

The manufacturing method of the polyester resin is not particularly limited, and a known method can be used. For example, there is a method of producing a polyester resin by condensing a polyester resin precursor containing at least one dicarboxylic acid compound and at least one glycol compound in the presence of a known compound such as a titanium compound. Materials used to produce polyester resin will be described below.

(Dicarboxylic acid compound) The dicarboxylic acid compound is a compound selected from the group consisting of dicarboxylic acid and dicarboxylic acid ester compounds. Examples of the dicarboxylic acid compound include dicarboxylic acids such as aliphatic dicarboxylic acid compounds, alicyclic dicarboxylic acid compounds, and aromatic dicarboxylic acid compounds, and methyl ester compounds and ethyl esters of these dicarboxylic acids. Compounds such as dicarboxylic acid esters. Among them, aromatic dicarboxylic acid or aromatic dicarboxylic acid methyl ester is preferred.

Examples of aliphatic dicarboxylic acid compounds include malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, dimer acid, and eicosane Diacid, pimelic acid, azelaic acid, methylmalonic acid and ethylmalonic acid. Examples of alicyclic dicarboxylic acid compounds include adamantane dicarboxylic acid, norbornene dicarboxylic acid, cyclohexane dicarboxylic acid, and decalin dicarboxylic acid.

Examples of aromatic dicarboxylic acid compounds include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid. Naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 5-sodium sulfonate isophthalate, phenyl Indanedicarboxylic acid, anthracenedicarboxylic acid, phenanthrenedicarboxylic acid, 9,9'-bis(4-dicarboxyphenyl)furnic acid, and their methyl esters. Among them, terephthalic acid or 2,6-naphthalenedicarboxylic acid is preferred, and terephthalic acid is more preferred.

Regarding the dicarboxylic acid compound, only one type may be used, or two or more types may be used in combination. When terephthalic acid is used as the dicarboxylic acid compound, terephthalic acid may be used alone or may be copolymerized with other aromatic dicarboxylic acids or aliphatic dicarboxylic acids such as isophthalic acid.

(diol compound) Examples of the diol compound include aliphatic diol compounds, alicyclic diol compounds, and aromatic diol compounds, with aliphatic diol compounds being preferred.

Examples of aliphatic diol compounds include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, and 1,3-butanediol. Alcohol and neopentyl glycol, ethylene glycol is preferred. Examples of the alicyclic diol compound include cyclohexanedimethanol, spirodiol, and isosorbide. Examples of the aromatic diol compound include bisphenol A, 1,3-benzenedimethanol, 1,4-benzenedimethanol, and 9,9'-bis(4-hydroxyphenyl)fluoride. Regarding the diol compound, only one type may be used, or two or more types may be used in combination.

The compound used for producing the polyester resin is not particularly limited, and known compounds that can be used in the synthesis of polyester resin can be utilized. Examples of the compound include alkali metal compounds (for example, potassium compounds, sodium compounds), alkaline earth metal compounds (for example, calcium compounds, magnesium compounds), zinc compounds, lead compounds, manganese compounds, cobalt compounds, aluminum compounds, Antimony compounds, titanium compounds, germanium compounds and phosphorus compounds. Among them, titanium compounds are preferable from the viewpoint of catalytic activity and cost. Regarding the above compounds, only one type may be used, or two or more types may be used in combination. It is preferred to use at least one metal compound and a phosphorus compound selected from the group consisting of potassium compounds, sodium compounds, calcium compounds, magnesium compounds, zinc compounds, lead compounds, manganese compounds, cobalt compounds, aluminum compounds, antimony compounds, titanium compounds and germanium compounds in combination. , it is better to use a titanium compound and a phosphorus compound together. When the above compounds are added, the added amount of each compound is usually 1 to 500 ppm by mass relative to the total mass of the polyester resin in terms of the metal element or phosphorus element, and a relatively greater amount is 1 to 100 ppm by mass. good.

The titanium compound may include preferred aspects, and is the same as the titanium compound used in the process 1 of the first embodiment. Moreover, the magnesium compound and the phosphorus compound may also include preferable aspects, respectively, and are the same as the magnesium compound and the phosphorus compound mentioned as the compound which can be used in the process 1 of 1st Embodiment.

(capping agent) In the production of polyester resin, an end-capping agent can be used as needed. By using an end-capping agent, a structure derived from the end-capping agent is introduced at the end of the polyester resin. There are no limitations on the end-capping agent, and known end-capping agents can be used. Examples of the terminal blocking agent include oxazoline-based compounds, carbodiimide-based compounds, and epoxy-based compounds. As the terminal blocking agent, the contents described in [0055] to [0064] of Japanese Patent Application Laid-Open No. 2014-189002 can also be referred to, and the contents of the above publications are incorporated into this specification.

(Other additives) Depending on the purpose, other metal compounds, nitrogen-containing alkaline compounds, antioxidants, antistatic agents, ultraviolet absorbers, fluorescent whitening agents, dyes, etc. may be included in the polyester resin.

The production method of the polyester resin is not particularly limited, and known production methods such as batch production, semi-batch production, and continuous production can be used. Examples of methods for producing polyester resins include transesterification reaction methods and direct esterification reaction methods. Among them, the method described in Process 1 of the above-mentioned first embodiment is particularly preferred as a method for producing the polyester resin. Furthermore, after these polymerization reactions, a solid-phase polymerization reaction may be performed.

The content of the polyester resin in the polyester base material relative to the total mass of the resin in the polyester base material is preferably 85 mass% or more, more preferably 90 mass% or more, further preferably 95 mass% or more, 98 Quality % or more is particularly good. The upper limit of the content of the polyester resin is not particularly limited, and can be appropriately set within a range of, for example, 100 mass % or less based on the total mass of the resin in the polyester base material.

The polyester base material may contain components other than the polyester resin (for example, the above-mentioned compounds, unreacted raw material components, particles, water, etc.). From the viewpoint that the effect of the present invention is more excellent, it is preferable that the polyester base material does not contain inorganic particles substantially. Examples of the inorganic particles contained in the polyester base material include inorganic particles contained in the particle-containing layer described below, and further examples include metal compounds and phosphorus compounds used in the process of polymerizing the polyester resin. Reaction, as inorganic particles (so-called internal particles) precipitated as metal phosphate salts. Moreover, from the viewpoint that the effect of the present invention is more excellent, it is preferable that the polyester base material does not contain organic particles substantially. Examples of the organic particles contained in the polyester base material include organic particles contained in the particle-containing layer described below.

＜Particle-containing layer＞ In the polyester film of this embodiment, from the viewpoint of improving transportability by imparting lubricity, it is preferable to have a particle-containing layer on at least one side of the polyester base material. Specifically, it can improve winding quality (suppress sticking), suppress the occurrence of damage and defects during transportation, and reduce transportation wrinkles during high-speed transportation. The particle-containing layer may be provided directly on the surface of the polyester base material, or may be provided via an intermediate layer. However, from the viewpoint of better productivity, it is preferable to provide it directly on the surface of the polyester base material. The particle-containing layer preferably contains particles and a binder. The particle-containing layer may contain additives in addition to particles and binders.

(particle) The average particle diameter of the particles contained in the particle-containing layer is not particularly limited, but is preferably 1 to 1000 nm, and more preferably 40 to 500 nm. Examples of particles include inorganic particles and organic particles. Examples of the inorganic particles include silicon dioxide particles (colloidal silicon dioxide), titanium dioxide particles (titanium oxide particles), calcium carbonate, barium sulfate, and aluminum oxide particles. Examples of organic particles include resin particles. Examples of resins constituting the resin particles include acrylic resins such as polymethyl methacrylate resin (PMMA), polyester resins, polysilicone resins, styrene resins, urethane resins, and styrene-acrylic resins. The resin particles may or may not have a cross-linked structure. Specifically, they are non-crosslinked acrylic resin particles, non-crosslinked styrene resin particles, cross-linked acrylic resin particles, cross-linked urethane resin particles and divinylbenzene cross-linked particles. In addition, in this specification, acrylic resin means the resin containing the structural unit derived from acrylic acid ester or methacrylic acid ester.

From the viewpoint of transportability, the content of particles in the particle-containing layer is preferably 0.1 to 30 mass%, and more preferably 1 to 25 mass%, based on the total mass of the particle-containing layer. In addition, the content of the particles is preferably 0.0001 to 0.01% by mass, and more preferably 0.0005 to 0.005% by mass relative to the total mass of the polyester base material.

(adhesive) The particle-containing layer preferably contains a binder. As the adhesive, resin adhesive is preferred. As the resin binder, non-polyester resins are preferred, and examples thereof include acrylic resins, urethane resins, polyester resins, and olefin resins, with acrylic resins, urethane resins, and olefin resins being preferred. As the binder, known resins can be used. In addition, the resin binder may be an acid-modified resin. Furthermore, the binder contained in the particle-containing layer may have a cross-linked structure. That is, the particle-containing layer may be a cross-linked film. The particle-containing layer may contain a single type of binder, or may contain two or more types of binders. The content of the binder relative to the total mass of the particle-containing layer is preferably 30 to 99.8% by mass, and more preferably 50 to 99.5% by mass.

(Additive) Examples of additives contained in the particle-containing layer include surfactants, paraffin waxes, antioxidants, ultraviolet absorbers, colorants, reinforcing agents, plasticizers, antistatic agents, flame retardants, antirust agents, and antibacterial agents. agent.

From the viewpoint of improving surface smoothness, the particle-containing layer preferably contains a surfactant. The surfactant is not particularly limited, and examples thereof include polysiloxane-based surfactants, fluorine-based surfactants, hydrocarbon-based surfactants, and fluorine-based surfactants (especially perfluorinated surfactants having 1 to 4 carbon atoms). Alkyl fluorine-based surfactants) or hydrocarbon-based surfactants are preferred. One type of surfactant may be used, or two or more types may be used in combination. The content of the surfactant is preferably 0.1 to 10% by mass relative to the total mass of the particle-containing layer, and from the viewpoint of more excellent surface smoothness, the content is more preferably 0.1 to 5% by mass.

From the viewpoint of low haze, the thickness of the particle-containing layer is preferably 1 nm to 1 μm, more preferably 1 to 500 nm, and further preferably 1 to 200 nm. The thickness of the particle-containing layer is the arithmetic mean of the thicknesses at five locations of a slice having a cross-section perpendicular to the main surface of the polyester film and measured using a scanning electron microscope (SEM).

[Physical properties, etc.] The polyester film of this embodiment may contain titanium, but preferably contains titanium. Moreover, the polyester film of this embodiment may contain the element derived from the compound added to the said polyester resin. Among them, the polyester film preferably contains at least one element selected from the group consisting of magnesium and phosphorus, and more preferably contains magnesium and phosphorus. Furthermore, the polyester film of this embodiment preferably contains at least one element selected from the group consisting of titanium, magnesium and phosphorus, and more preferably contains titanium, magnesium and phosphorus. The content of the above elements is preferably 1 to 500 ppm by mass, and more preferably 1 to 100 ppm by mass relative to the total mass of the polyester film. Furthermore, the content of metal elements and phosphorus elements contained in the polyester film can be measured by ICP-MS according to the method for measuring the content of antimony.

When the polyester film of this embodiment contains titanium, the content of the titanium element is preferably 1 to 30 mass ppm, more preferably 3 to 20 mass ppm, and further preferably 5 to 15 mass ppm. When the polyester film of this embodiment contains magnesium, from the viewpoint of being able to provide high electrostatic application properties, the content of the magnesium element is preferably 50 mass ppm or more relative to the total mass of the polyester film, and is preferably 50 to 100 ppm. The mass ppm is more preferable, the mass ppm of 60 to 90 is still more preferable, and the mass ppm of 70 to 80 mass ppm is particularly good. When the polyester film of this embodiment contains phosphorus, the content of the phosphorus element relative to the total mass of the polyester film is preferably 50 to 90 mass ppm, more preferably 60 to 80 mass ppm, and 65 to 75 mass ppm. For further improvement.

＜Thickness＞ From the viewpoint of more excellent optical failure suppression performance, the thickness of the polyester film of this embodiment is preferably 100 μm or less, more preferably 50 μm or less, and further preferably 35 μm or less. The lower limit of the thickness is not particularly limited, but from the viewpoint of improving strength and workability, it is preferably 1 μm or more, more preferably 5 μm or more, and further preferably 10 μm or more. The thickness of the polyester film was measured using a continuous stylus type film thickness meter. Specifically, the thickness of the polyester film was measured at 10 m along the longitudinal direction with a continuous stylus type film thickness meter. This measurement was performed at 5 locations with different positions in the width direction. The arithmetic mean of the measured values obtained was taken as the thickness. In addition, in the case of a polyester film less than 10 m, the thickness was measured using a stylus type film thickness meter at 5 different locations randomly selected from the polyester film, and the arithmetic mean of the measured values was determined as thickness.

[Manufacturing method] The method for producing the polyester film of this embodiment is not particularly limited as long as it can produce a polyester film having the above structure. An example of a method for producing a polyester film having a polyester base material and a particle-containing layer is as follows: after melt-extruding a polyester resin to produce a polyester base material, coating one side of the polyester base material with The cloth contains a particle-containing layer-forming composition containing particles and is then stretched; and a melt of polyester resin and a particle-containing layer-forming composition containing particles and a binder are co-extruded and then stretched.

When the polyester film of this embodiment is used to produce a dry film photoresist, after a polyester base material substantially containing no particles is produced by melt extrusion molding, one side of the polyester base material is coated with It is preferred that the composition of particles is then stretched to produce a polyester film. This makes it possible to reduce the number of particles contained in the polyester film as much as possible while maintaining lubricity, so that the haze of the polyester film can be lowered and a film with better optical failure suppression performance can be produced. Moreover, as a manufacturing method of the polyester film of this embodiment, including the preferable aspect, the method described as the manufacturing method of the polyester film of the said 1st Embodiment is mentioned.

〔use〕 The polyester film of this embodiment is excellent in the optical failure suppression effect, and therefore can be suitably used as a film for dry film photoresist production. Moreover, since the polyester film of this embodiment has excellent transparency, it can also be used as an optical film in addition to manufacturing a dry film photoresist. For example, the polyester film can be used as a protective film for various purposes, a supporting film for various purposes such as decorative sheets and decorative sheets, a molding film such as a decorative layer or a resin sheet, a film for optical displays, a conductive film, etc. Furthermore, since the polyester film of this embodiment is also excellent in smoothness, it can be used as a release film for various purposes such as manufacturing ceramic green sheets, a film for semiconductor manufacturing processes, a film for polarizing plate manufacturing processes, a film for magnetic tapes, and labels. Separators for adhesive films used in medical, medical and office supplies.

[Dry film photoresist (DFR)] The dry film photoresist (DFR) of the present invention has a polyester film and a photosensitive resin layer. DFR is generally used as a photosensitive transfer member. DFR may have an intermediate layer between the polyester film and the photosensitive resin layer. Here, the intermediate layer refers to all layers between the polyester film and the above-mentioned photosensitive resin layer.

The DFR of the present invention has a polyester film. Furthermore, when a polyester film is used as a support, a peelable support is preferable. The polyester film is as described above as the polyester film of the second embodiment. When the particle-containing layer is formed on only one surface of the polyester film, it is preferable that the photosensitive resin layer is formed on the surface of the polyester film opposite to the particle-containing layer.

As the photosensitive resin layer, a known photosensitive resin layer can be used. From the viewpoint of excellent lamination properties at high speed, a negative photosensitive resin layer is preferable. Specifically, a photosensitive resin layer including a binder polymer (preferably a polymer having an acid group), a polymerizable compound having an ethylenically unsaturated bond, and a photopolymerization initiator is preferred. As the photosensitive resin layer, for example, the photosensitive resin layer described in Japanese Patent Application Laid-Open No. 2016-224162 can be used. Furthermore, a photosensitive resin layer containing the binder polymer described in International Publication No. 2018/105313, a polymerizable compound having an ethylenically unsaturated bond, and a photopolymerization initiator can also be cited as a preferred embodiment. A more preferred embodiment includes a photosensitive resin layer including an alkali-soluble acrylic resin having a cyclic structure, a polyfunctional acrylate monomer, and an oxime-based photopolymerization initiator or a bisimidazole-type photopolymerization initiator.

It is preferable that the DFR has a protective film on the surface of the photosensitive resin layer opposite to the support side. It is also better to use polyester film as a protective film.

[DFR manufacturing method] The manufacturing method of DFR is not particularly limited, and DFR can be manufactured by known manufacturing methods. An example of a method for producing DFR is a process of separately preparing compositions for forming each layer such as a polyester resin composition by sequentially mixing the structural components and solvents of each layer according to the desired layer structure. And a process of coating the above composition on the surface of the polyester film to form a coating layer and then drying the coating layer to form each layer, manufacturing a polyester film, an intermediate layer and a photosensitive resin layer provided as necessary of DFR.

The DFR of the present invention has an excellent effect of being able to form a photoresist pattern with few optical defects even when used to form a high-definition photoresist pattern. Therefore, the DFR of the present invention is preferably used for manufacturing photoresist patterns and circuit wiring.

[Third Embodiment: Polyester Film (2)] The polyester film according to the third embodiment of the present invention is characterized in that the total number of foreign matter and voids with a diameter of 9 to 20 μm observed using a transmission polarizing microscope is 1.7 Pieces/mm ³ or less.

Since the polyester film of this embodiment has the above-mentioned structure, the effect of suppressing local concave defects in the ceramic green sheet produced using the polyester film of this embodiment is exerted (hereinafter, also described as "concave defect suppression effect"). .) The details of the reason are not yet clear, but a polyester film whose density of foreign matter and voids with a diameter of 9 to 20 μm is less than a predetermined value has few convex parts on the surface, so it is presumed that it is due to the use of polyester. The ceramic green sheet made of the film can further suppress the occurrence of local concave defects and further improve the smoothness.

[Characteristics of polyester film] <Total number of foreign matter and voids> In the polyester film of this embodiment, the total number of foreign matter and voids with a diameter of 9 to 20 μm observed using a polarizing microscope is 1.7/mm ³ or less. The unit of "pieces/ ^mm3 or less" mentioned above refers to the total number of foreign matter or voids per unit volume of the polyester film observed using a polarizing microscope. The foreign matter and voids with a diameter of 9 to 20 μm contained in the polyester film, and the following foreign matter and voids with a diameter of 3 μm or more and less than 9 μm are as described in the second embodiment. In addition, the total number of foreign matter or voids with a diameter per unit volume of the polyester film of 9 to 20 μm can be measured by the method described in the second embodiment as “foreign matter per 500 ^mm2 observation area of the polyester film or Divide the "number of voids" by the "thickness of the polyester film" and convert the resulting value into a volume per ¹ mm3 of the polyester film. The total number of foreign matter and voids whose diameter per unit volume of the polyester film is 3 μm or more and less than 9 μm can also be determined by the same method.

From the viewpoint of being more effective in suppressing concave defects, it is preferable that the total number of foreign matter and voids with a diameter of 9 to 20 μm observed using a polarizing microscope is 1.5/mm ³ or less. The lower limit of the total number of foreign matter and voids with a diameter of less than 9 to 20 μm is not particularly limited, and may be 0/mm ³ . As a means of setting the total number of foreign matter and voids with a diameter of 9 to 20 μm within the above range, there are methods of reducing the antimony content contained in the polyester film to be described below to 1 mass ppm or less, and in producing the polyester film. In the case of an ester film, a process in which a melt of the polyester resin used as a raw material is introduced and filtered based on the process 2 of the first embodiment is used.

From the viewpoint of a more excellent concave defect suppression effect, the total number of foreign matter and voids with a diameter of 3 μm or more and less than 9 μm observed using a polarizing microscope on the polyester film is preferably 27.0 pieces/mm or less, and 26.0 pieces/ ^mm3 or less. mm ³ or less is better. The lower limit of the total number of foreign matter and voids having a diameter of 3 μm or more and less than 9 μm is not particularly limited, and may be 0 pieces/mm ³ . In addition, the total number of foreign matter and voids with a diameter exceeding 20 μm observed using a polarizing microscope on the polyester film is preferably less than 1/500mm ² , and more preferably 0/mm ³ (that is, not observed).

<Content of antimony> The content of antimony (Sb) contained in the polyester film is preferably 1 mass ppm or less, more preferably 0.7 mass ppm or less, and further preferably 0.6 mass ppm or less relative to the total mass of the polyester film. Best, below 0.5 mass ppm is particularly good. By setting the antimony content within the above range, it is easier to produce a polyester film in which the total number of foreign matter and voids with a diameter of 9 to 20 μm observed with a transmission polarizing microscope is 1.7/mm ³ or less. The lower limit of the antimony content is not particularly limited, but may be 0 ppm by mass relative to the total mass of the polyester film. The method for measuring the antimony content contained in the polyester film is as described in the second embodiment.

＜Haze＞ The haze of the polyester film of this embodiment is preferably 5% or less, more preferably 2.0% or less, and further preferably 1.5% or less. The lower limit value is not particularly limited, but 0% or more is preferred. The measurement method for measuring the haze of the polyester film is as described in the second embodiment.

[Structure] The polyester film of this embodiment may have a single-layer structure including only a polyester base material formed using a melt of polyester resin, or may have a polyester base material formed using a melt of polyester resin and a film containing particles. Particles contain a multi-layered structure of layers. When the polyester film has a particle-containing layer, one particle-containing layer may be disposed on one side of the polyester base material, or two particle-containing layers may be disposed on both sides of the polyester base material. Among them, it is preferable to arrange one particle-containing layer on one side of the polyester base material. The polyester film may have a polyester base material and another layer other than the particle-containing layer. Examples of such other layers include an adhesive layer, a peeling layer, an antistatic layer, and an oligomer precipitation preventing layer. Furthermore, an intermediate layer such as a primer layer may be provided between the polyester base material and the particle-containing layer. The thickness of these other layers is preferably 1 nm to 1 μm, and more preferably 30 to 500 nm.

The polyester base material and the particle-containing layer that the polyester film of this embodiment may have, and the physical properties of the polyester film are as described in the second embodiment except for the following matters.

＜Thickness＞ From the viewpoint of being able to suppress manufacturing costs, the thickness of the polyester film of this embodiment is preferably 75 μm or less, more preferably 50 μm or less, and further preferably 35 μm or less. The lower limit of the thickness is not particularly limited, but from the viewpoint of improving strength and workability, 5 μm or more is preferred, 10 μm or more is more preferred, 18 μm or more is further preferred, and 25 μm or more is particularly preferred. The method for measuring the thickness of the polyester film is as described in the second embodiment.

[Manufacturing method] The method for producing the polyester film of this embodiment is not particularly limited as long as it can produce a polyester film having the above structure. An example of a method for producing a polyester film having a polyester base material and a particle-containing layer is as follows: after melt-extruding a polyester resin to produce a polyester base material, coating one side of the polyester base material with The cloth contains a particle-containing layer-forming composition containing particles and is then stretched; and a melt of polyester resin and a particle-containing layer-forming composition containing particles and a binder are co-extruded and then stretched.

When the polyester film of this embodiment is used to produce a dry film photoresist, after a polyester base material substantially containing no particles is produced by melt extrusion molding, one side of the polyester base material is coated with It is preferred that the composition of particles is then stretched to produce a polyester film. This makes it possible to reduce the number of particles contained in the polyester film as much as possible while maintaining lubricity, and to produce a ceramic green sheet that can further suppress local concave defects. Moreover, as a manufacturing method of the polyester film of this embodiment, including the preferable aspect, the method described as the manufacturing method of the polyester film of the said 1st Embodiment is mentioned.

〔use〕 The polyester film of this embodiment has an excellent concave defect suppressing effect and is therefore preferably used as a film for producing ceramic green sheets. Furthermore, since the polyester film of this embodiment has excellent smoothness, it can also be used as a film for semiconductor manufacturing processes, a film for polarizing plate manufacturing processes, a film for tapes, and an adhesive film for labels, medical and office supplies, etc. of separate pieces. Furthermore, the polyester film of this embodiment is excellent in transparency and optical failure suppression effect, and can be used as an optical film. For example, the polyester film can be used as a film for dry film photoresist production, a protective film for various purposes, a supporting film for various purposes such as decorative sheets and decorative sheets, a decorative layer and resin sheet and other molding films, and a film for optical displays. , and conductive films, etc.

[Method for manufacturing ceramic green sheets] The method of manufacturing a ceramic green sheet using the polyester film of this embodiment is not particularly limited and can be implemented by a known method. An example of a method for producing a ceramic green sheet is to apply the prepared ceramic slurry to one main surface of a release film having the polyester film according to this embodiment, and to dry and remove the solvent contained in the ceramic slurry. This method of forming ceramic green sheets.

Regarding the structure of the release film, it suffices as long as it has the polyester film of this embodiment and the formed ceramic green sheet can be peeled off from the main surface (hereinafter also referred to as the "release surface") on which the ceramic slurry is applied. Special restrictions. The release film may be a laminated film including the polyester film of this embodiment and a release layer. In addition, when the formed ceramic green sheet can be peeled off (for example, when the ceramic green sheet has peeling properties), the polyester film of the present embodiment may have a release film without a release layer, or may have a release layer. The polyester film of this embodiment is used alone as a release film.

As the release film, a laminated film having the polyester film of this embodiment and a release layer is preferred. In the above laminated film, the release layer is arranged as the outermost layer, and one main surface of the release layer becomes the release surface on which the ceramic green sheet is formed. When the particle-containing layer is formed on only one surface of the polyester film, it is preferable that the peeling layer is formed on the surface of the polyester film opposite to the particle-containing layer. The said laminated film may have an intermediate layer between a polyester film and a release layer. Here, the intermediate layer refers to all layers between the polyester film and the release layer. Examples of the intermediate layer include a non-polyester resin layer and an antistatic layer that suppress precipitation of oligomers from the polyester base material.

The release film can be produced, for example, by providing a release layer on one main surface of the polyester film. The release layer may be directly provided on the surface of the polyester base material, or may be provided on the polyester base material via other layers. From the viewpoint of more excellent smoothness, it is preferable to provide the release layer directly on the surface of the polyester base material. Moreover, if necessary, the release layer may be laminated on the polyester film via the above-mentioned intermediate layer.

The composition of the release layer is not particularly limited as long as the ceramic green sheet can be releasably produced, but the release layer preferably contains a resin as a release agent. The resin contained in the release layer is not particularly limited, and examples thereof include silicone resins, fluororesins, alkyd resins, acrylic resins, various paraffins, and aliphatic olefins from the viewpoint of better release properties of the ceramic green sheet. In other words, polysilicone resin is better. It is also preferable that the peeling layer is a hardened layer obtained by hardening the components contained in the peeling layer. In addition to the resin as a release agent, the release layer may also contain other components such as resins and additives other than the release agent. Examples of additives include light peeling additives and heavy peeling additives for adjusting peeling force, adhesion improving agents, and antistatic agents.

Polysilicone resin refers to a resin with a polysilicone structure in the molecule. Examples of polysilicone resins include hardened polysilicone resins, polysilicone graft resins, and modified polysilicone resins such as alkyl-modified ones. Reactive hardened polysilicone resins are preferred. Examples of the reactive curable silicone resin include addition reaction type silicone resins, condensation reaction type silicone resins, and ultraviolet or electron beam curing type silicone resins.

From the viewpoint of an excellent balance between peeling performance and smoothness of the surface of the peeling layer, the thickness of the peeling layer is preferably 10 to 1000 nm, and more preferably 30 to 700 nm. The thickness of the peeling layer is the arithmetic mean of the thickness of five places in the slices measured using a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

An example of a method for forming a release layer on a polyester film is to apply a release layer-forming composition to the surface of the polyester film, dry the coated film to remove the solvent, and heat or irradiate with light as necessary. As the composition for forming a peeling layer, a known composition for forming a peeling layer can be used. The composition for forming a release layer can be prepared, for example, by mixing a release agent, a solvent, and other components added as necessary. Examples of the solvent include water, alcohol-based solvents, ether-based solvents, ketone-based solvents, and aromatic hydrocarbon-based solvents. The peeling layer forming composition may contain one solvent alone, or may contain two or more solvents. The content of the solvent is preferably 80 to 99.5% by mass relative to the total mass of the peeling layer forming composition. In addition, the total content of components (solid content) other than the solvent in the composition for forming a peeling layer is preferably 0.5 to 20% by mass relative to the total mass of the composition for forming a peeling layer.

The coating method of the peeling layer forming composition and the drying method of the coating film are not particularly limited, and known methods can be used. Specific examples of the coating method include the in-line coating method listed in Step 4 of the polyester film manufacturing method, and off-line coating in which the polyester film is manufactured and then coated using a coater. Law. Examples of the coating method include gravure coating, rod coating, spray coating, spin coating, blade coating, roll coating, and die coating. In order to improve the adhesion between the polyester film and the release layer, pre-treatment such as anchor coating, corona treatment, and plasma treatment can also be performed on the surface of the polyester film before setting the release layer.

The method of applying the ceramic slurry to the release surface of the release film is not particularly limited. For example, a method of applying a ceramic slurry in which ceramic powder and a binder are dispersed in a solvent and removing the solvent by heating and drying can be used. and other well-known methods. Examples of the binder include polyvinyl butyral. Examples of the solvent include ethanol and toluene.

The produced ceramic green sheets are used to manufacture ceramic condensers. As a method of manufacturing a ceramic condenser using ceramic green sheets, a known method can be applied, and examples thereof include the following methods. First, internal electrodes are provided on the laminate of the release film and the ceramic green sheet produced by the above method by coating or printing of conductive paste. Next, the release film is removed from the laminate of ceramic green sheets, ceramic green sheets with internal electrodes are sequentially laminated, and the obtained laminate is pressurized to produce an intermediate laminate. After the intermediate laminated body is cut into a desired shape, the cut intermediate laminated body is fired to obtain a ceramic body. Next, external electrodes electrically connected to the internal electrodes using a conductive paste such as silver are formed on both end surfaces of the fired intermediate laminated body, thereby obtaining a ceramic condenser.

The release film including the polyester film of this embodiment can be used as a protective film for dry film photoresist, a decorative layer, a film for sheet forming such as a resin sheet, a release film for semiconductor manufacturing processes, etc., and a polarizing plate manufacturing process. Release films for use, and separators for adhesive films for labels, medical and office supplies, etc. [Example]

Hereinafter, the present invention will be described in further detail based on examples. The materials, usage amounts, ratios, treatment contents, treatment steps, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention should not be construed to be limited by the examples shown below. In addition, unless otherwise specified, "parts", "ppm" and "%" are based on mass.

In this embodiment, the mark of a simple "film" includes both the aspect with only the polyester base material and the aspect with the polyester film including the polyester base material and the particle-containing layer. In addition, the mark of "film" includes all unstretched films, uniaxially stretched films, and biaxially stretched films.

First, the manufacturing method of the film used in each Example and Comparative Example is demonstrated.

[Example 1] [Manufacture of polyester pellets before cleaning] Polyester pellets were produced by using terephthalic acid and ethylene glycol as raw materials, using an antimony compound, and performing esterification reaction and polycondensation reaction in a continuous polymerization device. The continuous polymerization device includes a mixing tank, a first esterification reaction tank, a second esterification reaction tank, a first polycondensation reaction tank, a second polycondensation reaction tank, and a third polycondensation reaction tank in this order. Hereinafter, the first esterification reaction tank, the second esterification reaction tank, the first polycondensation reaction tank, the second polycondensation reaction tank and the third polycondensation reaction tank are also collectively referred to as “reaction tanks”. In the production of polyester particles, the method described in (1) and (2) of [Production of polyester film] described below is followed except that an antimony compound is added in place of the titanium compound. After the continuous production of polyester pellets was completed, the reaction tank included in the continuous polymerization apparatus was cleaned as shown below.

[Cleaning of reaction tank] In a reaction tank used for polymerization of polyester resin, add triethylene glycol in an amount equivalent to 70 volume % of the reaction tank as a cleaning liquid, replace the head space of the reaction tank with nitrogen, and stir the cleaning liquid. Heat to 270°C. The cleaning liquid was stirred at 270° C. for 6 hours, then cooled to room temperature, and then the cleaning liquid was discharged. The pipes connecting the reaction tanks for transporting the product were cleaned by flowing a mixture of triethylene glycol and water. Visual inspection of the inside of the reaction tank revealed that stains remained. Next, the stains in the reaction tank were removed, and the liquid-contacting parts were polished with solvent-free until the liquid-contacting parts of the reaction tank returned to metallic luster, thereby cleaning. Afterwards, high-pressure water washing was used to completely remove the stains inside the reaction tank. All the tanks and piping used for the polymerization of polyethylene terephthalate were cleaned in the same manner as the above-mentioned cleaning method of the reaction tank.

[Manufacturing of polyester film] A polyester film was continuously produced by following the steps (1) to (3) below using a continuous polymerization device equipped with a cleaned reaction tank.

(1) Esterification reaction 4.7 tons of high-purity terephthalic acid and 1.8 tons of ethylene glycol were charged into the mixing tank as polyester resin precursors, and the mixture was mixed for 90 minutes to form a slurry. The obtained slurry was continuously supplied from the mixing tank to the first esterification reaction tank at a flow rate of 3800 kg/h. Furthermore, an ethylene glycol solution of a citric acid chelate titanium complex (VERTEC AC-420, manufactured by Johnson Matthey plc) in which citric acid is coordinated to the Ti element was continuously supplied to the first esterification reaction tank, and the solution was heated in a tank at 251°C. The reaction was carried out with stirring at an internal temperature of about 4.3 hours. At this time, the citric acid chelate titanium complex was continuously added so that the added amount of Ti became 7 ppm in terms of element conversion relative to the total amount of the polyester resin precursor. At this time, the acid value of the oligomer obtained was 500 eq/ton.

The reactant obtained in the first esterification reaction tank was transferred to the second esterification reaction tank, and reacted with stirring at an internal tank temperature of 250°C with an average residence time of 1.2 hours to obtain an acid value. is 190eq/ton of oligomers. The inside of the second esterification reaction tank is divided into three areas including the first area, the second area, and the third area in the order in which oligomers are supplied, and the ethylene glycol solution of magnesium acetate is continuously supplied from the second area. , so that the added amount of Mg becomes 75 ppm in terms of element conversion value relative to the total amount of oligomers, and then the ethylene glycol solution of trimethyl phosphate is continuously supplied from the third area, so that the added amount of P becomes 75 ppm in terms of element conversion value The total amount of oligomers was 65 ppm.

(2) Polycondensation reaction: The esterification reaction product obtained above is continuously supplied to the first polycondensation reaction tank, and under stirring, at a reaction temperature of 270°C and an internal tank pressure of 20torr (2.67×10 ^-3 MPa), The polycondensation was carried out with an average residence time of approximately 1.8 hours. Furthermore, the intermediate polymer obtained in the first polycondensation reaction tank was transferred to the second polycondensation reaction tank, and under stirring, the temperature in the tank was 276°C and the pressure in the tank was 3.0 torr (3.99×10 ^-4 MPa). , the reaction (polycondensation) was carried out with a residence time of about 1.2 hours. Next, the intermediate polymer obtained in the second polycondensation reaction tank was further transferred to the third polycondensation reaction tank, and was retained in the tank at an internal temperature of 278°C and an internal pressure of 1.0 torr (1.33×10 ^-4 MPa). The reaction (polycondensation) was performed for 1.5 hours, and polyethylene terephthalate (PET) was discharged from the third polycondensation reaction tank as a product. The obtained product was analyzed for Sb content using an ICP-MS analyzer (manufactured by Agilent Technologies Japan, Ltd., "Agilent 7800 ICP-MS"). As a result, the Sb content was 0.9 ppm relative to the total mass of the product.

Next, the obtained product was discharged into cold water in the form of strands, and was immediately cut to produce polyester resin pellets <cross section: major diameter approximately 4 mm, minor diameter approximately 2 mm, length: approximately 3 mm>. The process from charging the polyester resin precursor to discharging the product from the third polycondensation reaction tank to producing pellets was continuously implemented. That is, after the production of pellets of a product obtained by polymerization of a polyester resin precursor at the beginning of charging is started, the production of pellets is continued continuously.

(3) Filmization After drying the pellets obtained in the above (2) until the moisture content is 50 ppm or less, the pellets are put into the hopper of a uniaxial kneading extruder with a diameter of 30 mm, the pellets are heated to 280°C and melted, and the molten pellets are extruded. out. After passing the extruded molten material (melt) through the filter device A described below, it is extruded from the die to a cooling casting drum at 25° C., and is brought into close contact with the casting drum using an electrostatic application method. By peeling off the film using a peeling roller arranged to face the casting drum, an unstretched polyester film containing no particles was obtained. Furthermore, in Example 1, the continuous polymerization time (hereinafter, also referred to as "Elapsed time.") Unstretched polyester film was produced from the pellets produced after 72 hours. The filter device A is a filter device having the same structure as the filter device 36 shown in FIG. 2 , and is a laminate with a filter material including a fibrous metal sintered body made of a nonwoven fabric made of stainless steel fibers and a powdery metal sintered body. A filter is provided, and a filtration device is provided with 145 laminated filters whose porosity and layer thickness of the sintered body are adjusted so that the filtration precision of the fibrous metal sintered body becomes 3 μm.

Referring to the conditions described in [0160] to [0169] of International Publication No. 2020/158316, the composition for forming the particle-containing layer is applied to the surface of the film obtained by longitudinally stretching the unstretched polyester film. The obtained film with the particle-containing layer was stretched to produce a biaxially stretched polyester film, which was wound at intervals of 7000 m. The thickness of the produced biaxially stretched polyester film was 16 μm (including the particle-containing layer with a thickness of 40 nm). The obtained polyester film was analyzed using an ICP-MS analyzer in the same manner as above, and the content of each element contained in the film was measured. As a result, the Sb content was 0.8 ppm, the Ti content was 7 ppm, the Mg content was 75 ppm, and the P content was 65 ppm relative to the total mass of the polyester film.

[Example 2 to Example 5] A filter device B in which the filtration precision of the fibrous metal sintered body in the filter device A was changed to 2 μm was used, and a polymer produced using the product discharged from the third polycondensation reaction tank after the elapsed time listed in Table 1 was used. Except for the ester particles, the biaxially stretched polyester films of Examples 2 to 5 were produced in the same manner as in Example 1.

[Example 6 to Example 7] In the film manufacturing process, the amount of molten polyester pellets extruded from the die to the casting drum was changed so that the thickness of the biaxially stretched polyester film becomes the thickness described in Table 1. , in the same manner as in Example 5, the biaxially stretched films of Example 6 and Example 7 were produced respectively.

[Example 8 to Example 9] In the production of polyester particles before cleaning, the titanium compound described in (1) of [Production of polyester film] in Example 1 was used instead of the antimony compound, and the process described in Utilization Process Table 1 was used. Biaxially stretched polyester films of Examples 8 and 9 were produced in the same manner as Example 2, except that polyester pellets were produced from the product discharged from the third polycondensation reaction tank after a certain time.

[Comparative example 1] In the [Production of Polyester Film] of Example 1, an antimony compound was continuously added to the first esterification reaction tank in an amount of 7 ppm by mass based on the Sb element conversion value relative to the total amount of the polyester resin precursor. (antimony trioxide, "PATOX-C" manufactured by Nihon Seiko Co., Ltd.) was used instead of the citric acid chelate titanium complex, and polyester particles were continuously produced. The procedure was the same as in Example 5 except that The biaxially stretched polyester film of Comparative Example 1 was produced.

[Comparative example 2] In the production of the polyester film, a biaxially stretched polyester film was produced in the same manner as in Example 5, except that the melt of the polyester particles passed through a filtration device C described below. Here, the filter device C has a fibrous metal sintered body and is provided with 145 filters "NF2M-4C" (manufactured by Nippon Seisen Co., Ltd.) equipped with a filter material with a filtration accuracy of 4 μm.

[Comparative example 3] The biaxially stretched polyester film of Comparative Example 3 was produced in the same manner as in Example 5, except that the reaction tank was not cleaned before producing the polyester film.

[Reference Example 1 ~ Reference Example 2] A biaxially stretched PET film "Lumirror 16FB40" (manufactured by TORAY INDUSTRIES, INC.) with a three-layer structure having a particle-containing layer on both the front and back sides was prepared (Reference Example 1). Furthermore, a biaxially stretched PET film "Lumirror 16KS40" (manufactured by TORAY INDUSTRIES, INC.) with a three-layer structure having a layer containing fine particles on both the front and back sides was prepared (Reference Example 2).

Regarding the products used to produce films in Examples 2 to 9 and Comparative Examples 1 to 3, the films produced in Examples 2 to 9 and Comparative Examples 1 to 3, and the reference examples The biaxially stretched PET films used in Reference Examples 1 to 2 were analyzed using an ICP-MS analyzer in the same manner as in Example 1, and the contents of each element were measured. Table 1 shows the measurement results of respective Sb element contents. In any one of Examples 2 to 9 and Comparative Examples 1 to 3, the Ti content was 7 ppm, the Mg content was 75 ppm, and the P content was 65 ppm with respect to the total mass of the polyester film. In addition, the unstretched polyester films produced in Examples 1 to 9 and Comparative Examples 1 to 3 did not contain inorganic particles and organic particles.

[Measurement of films] <Total number of foreign matter and voids> Visible light was irradiated from the smooth surface side of each film (surface roughness was measured using an optical interference roughness meter, and the surface with small roughness was measured using an optical interference roughness meter), and a transmission polarizing microscope (manufactured by OLYMPUS Corporation) was used , BX51) At a magnification of 100 times, the 5 mm × 5 mm square field of view of each film was observed, and the foreign matter and voids with a diameter of 9 to 20 μm and those with a diameter of 3 μm or more and less than 9 μm in the thickness direction of the film were counted. The number of foreign objects and gaps. For the measurement of foreign matter and voids, foreign matter and voids present inside the film were counted by observing the change in color (refractive index change) of the resin around the foreign matter or void using a transmission-type polarizing microscope equipped with a polarizing lens. Furthermore, by using application software ("XD 2D Measurement" manufactured by OLYMPUS Co., Ltd.), the field of view was enlarged on the monitor for observation, and minute foreign objects and gaps were also measured. For each film, conduct the above observations and measure foreign matter and voids in 20 arbitrarily selected fields of view, and calculate the total number of measured foreign matter and voids as foreign matter in 5mm × 5mm × 20 fields of view = 500mm ² and the total number of gaps.

Furthermore, based on the total calculation result of the number of foreign matter and voids measured by the above method and the volume obtained by multiplying the observation field of view and thickness of each film, the diameter per unit volume of each film was calculated to be 9 to 20 μm. The total number of foreign matter and voids (pieces/mm ³ ), and the total number of foreign matter and voids whose diameter per unit volume of each film is 3 μm or more and less than 9 μm (pieces/mm ³ ). Furthermore, according to the above-mentioned method, foreign matter and voids exceeding 20 μm in diameter were measured, but foreign matter and voids exceeding 20 μm in diameter were not observed in any film.

＜Measurement of haze＞ The haze of the film produced or prepared in each example was measured by using a haze meter (NDH-2000, manufactured by NIPPON DENSHOKU INDUSTRIES Co., Ltd.) according to the method of JIS K 7105. The measurement results are shown in Table 1.

＜Production of photosensitive transfer member＞ The film obtained in each example was used as a support for the photosensitive transfer member. That is, the thermoplastic resin layer-forming coating liquid containing the following formula F is applied to the surface of the obtained film on the opposite side to the particle-containing layer, and the obtained coated film is dried at 80° C. A thermoplastic resin layer is formed. Next, after applying the coating liquid for forming a water-soluble resin layer containing the following formula G on the thermoplastic resin layer, the obtained coating film was dried at 80° C. to form a water-soluble resin layer. Furthermore, after applying the coating liquid for forming a photosensitive resin layer containing the following formula H on the water-soluble resin layer, the obtained coating film was dried at 80°C to form a photosensitive resin layer. Finally, a PET film (Lumirror 16KS40, manufactured by TORAY INDUSTRIES, INC.) as a protective film was pressed onto the surface of the photosensitive resin layer, and the obtained laminate was wound to produce a roller-shaped photosensitive transfer film. Print components. The photosensitive transfer member is an example of DFR and has a layer structure including a support/thermoplastic resin layer/water-soluble resin layer/photosensitive resin layer/protective film. The thickness of the thermoplastic resin layer is 2 μm, the thickness of the water-soluble resin layer is 1 μm, and the thickness of the photosensitive resin layer is 2 μm. Furthermore, regarding the films of Reference Example 1 and Reference Example 2, a thermoplastic resin layer, a water-soluble resin layer, a photosensitive resin layer and a protective film were laminated on a smoother surface by the above method.

(Formulation F: Coating liquid for thermoplastic resin layer formation) ·Copolymer obtained by polymerizing benzyl methacrylate, methacrylic acid and acrylic acid (mass ratio of each monomer = 75:10:15, molecular weight 30,000, water dispersion with solid content concentration 30%) 22.7 share ·3,6-Bis(diphenylamine)fluorane: 0.12 parts ·Oxime sulfonate type photoacid generator (synthesized according to paragraph 0227 of Japanese Patent Application Publication No. 2013-047765): 0.2 parts ·Tricyclodecane dimethanol diacrylate: 3.32 parts ·UV curable acrylic urethane oligomer ("8UX-015A" manufactured by TAISEI FINE CHEMICAL CO,.LTD., 15 functions): 1.66 parts ·Polyfunctional acrylate monomer ("ARONIX (registered trademark) TO-2349" manufactured by TOAKASEI.CO., LTD.): 0.55 parts ·Surfactant ("MEGAFAC (registered trademark) F-552" manufactured by DIC CORPORATION): 0.02 parts

(Formulation G: Coating liquid for forming water-soluble resin layer) ·Polyvinyl alcohol ("KURARAY POVAL (registered trademark) 4-88LA" manufactured by KURARAY CO., LTD.): 3.22 parts ·Polyvinylpyrrolidone ("K-30" manufactured by NIPPON SHOKUBAI CO., LTD.): 1.49 parts ·Surfactant ("MEGAFAC F-444" manufactured by DIC CORPORATION): 0.0035 parts ·Methanol (manufactured by MITSUBISHI GAS CHEMICAL COMPANY, INC.): 57.1 parts ·Ion exchange water: 38.12 parts

(Formulation H: Coating liquid for forming photosensitive resin layer) ·Copolymer obtained by polymerizing styrene, methacrylic acid and methyl methacrylate (mass ratio of each monomer = 52:29:19, molecular weight 60,000, water dispersion with solid content concentration 30%) :25.2 servings ·Colorless crystal violet: 0.06 parts ·Photopolymerization initiator (2-(2-chlorophenyl)-4,5-diphenylimidazole dimer): 1.03 parts ·4,4’-Bis(diethylamino)benzophenone: 0.04 parts ·N-Phenylaminemethylmethyl-N-carboxymethylaniline: 0.02 parts ·Ethoxylated bisphenol A dimethacrylate ("NK Ester BPE-500" manufactured by Shin-Nakamura Chemical Co., Ltd.): 5.61 parts ·Polyfunctional acrylate monomer ("ARONIXM-270" manufactured by TOAKASEI.CO., LTD.): 0.58 parts ·Phenthiol: 0.04 parts ·4-hydroxymethyl-4-methyl-1-phenyl-3-pyrazolinone: 0.002 parts ·Surfactant ("MEGAFAC F-552" manufactured by DIC CORPORATION): 0.048 parts ·Propylene glycol monomethyl ether acetate: 19.7g ·Methyl ethyl ketone: 43.8 parts

[Optical failure evaluation (pinhole evaluation)] A copper layer with a thickness of 200 nm was formed on a polyethylene terephthalate (PET) film with a thickness of 100 μm by sputtering, thereby producing a PET substrate with a copper layer. The roller-shaped photosensitive transfer member produced above was released, and the protective film was peeled off from the photosensitive transfer member. Next, the photosensitive transfer member was bonded to the PET substrate with the copper layer so that the photosensitive resin layer and the copper layer exposed by peeling off the protective film were in contact with each other, thereby obtaining a laminated body. For this laminating process, the roller temperature is 100°C, the linear pressure is 1.0MPa, and the linear speed is 4.0m/min.

The obtained laminate was irradiated with an ultra-high-pressure mercury lamp (main wavelength of exposure: 365 nm) from the side of the support (a PET substrate other than the film or the PET substrate with the copper layer produced or prepared in each example), and the temperature was 180 mJ/cm ² The exposure amount exposes the entire surface of the photosensitive resin layer. After peeling off the support from the exposed laminate, the surface of the laminate on the side where the thermoplastic resin layer, water-soluble resin layer and photosensitive resin layer were laminated was tested for 30 seconds using a 1.0% sodium carbonate aqueous solution with a liquid temperature of 25°C. Seconds of spray development. After spray development, observe the entire exposed photosensitive resin layer to confirm whether there are pinholes. It is considered that pinholes in the exposed photosensitive resin layer are generated by generating unexposed portions in the photosensitive resin layer due to foreign matter or voids contained in the support, and then removing the photosensitivity through the subsequent development process. The unexposed part of the resin layer, and the water-soluble resin layer and the thermoplastic resin layer laminated on the unexposed part. When pinholes were generated in the photosensitive resin layer after exposure, the diameter of the pinholes was measured. As a result of observing the laminated body, if no pinholes are found in the photosensitive resin layer, or if pinholes are found in the photosensitive resin layer but the pinhole diameter is 3 μm or less, it is included in the allowable range.

Table 1 below shows, for each example, the film production process, the Sb content of the particles used to produce the film, the composition and physical properties of the produced film, and the above evaluation results. In the table, the "metal compound" column indicates the metal compound used in (1) esterification reaction in the production of polyester film. The mark "Ti" indicates the use of titanium compounds, and the mark "Sb" indicates the use of antimony. compound. In the table, the "yes" mark in the "Cleaning Reaction Tank" column indicates that a cleaned reaction tank was used to produce polyester pellets, and the "no" mark indicates that an uncleaned reaction tank was used to produce polyester pellets. The "Product type before cleaning" column indicates the metal compound used in the esterification reaction in the production of polyester pellets before cleaning the reaction tank. The mark "Ti" indicates the use of titanium compounds, and the mark "Sb" indicates the use of of antimony compounds. The "elapsed time" column indicates whether the polyester pellets used to produce the film are polyester pellets that are produced when a certain time has elapsed since the start of charging the polyester resin precursor among the polyester pellets that are continuously produced using a reaction tank. Particles.

The "Sb [ppm]" column of "Particles" indicates the Sb content (unit: mass ppm) relative to the total mass of polyester particles analyzed using an ICP-MS analysis device. The "Melted Filter" column indicates the filtration accuracy (unit: μm) of the fibrous metal sintered body contained in the filter material.

The "3 to 9 μm foreign matter and voids" column of "Film" indicates the total number of foreign matter and voids with a diameter of 3 μm or more and less than 9 μm per ^500mm2 film measured by the above method. The "9 to 20 μm foreign matter and voids" column indicates Indicates the total number of foreign matter and voids with a diameter of 9 to 20 μm in a ^500mm2 film measured by the above method. In addition, the numerical values of foreign matter and voids in Reference Example 1 and Reference Example 2 are reference values. In Reference Example 1, they represent the total number of foreign matter and voids with a diameter of 1.5 to 4.5 μm in a 500 ^mm film measured according to the above method. , in Reference Example 2, represents the total number of foreign matter and voids with a diameter of 5 μm or more in a 500 mm ² film measured according to the above method.

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Comparative example 1 Comparative example 2 Comparative example 3 Reference example 1 Reference example 2 Manufacturing process metal compounds Ti Ti Ti Ti Ti Ti Ti Ti Ti sb Ti Ti - - Reaction tank cleaning have have have have have have have have have have have without - - Manufactured varieties before cleaning sb sb sb sb sb sb sb Ti Ti sb sb sb - - elapsed time 72 48 72 120 216 216 216 48 216 216 216 216 - - particles Sb[ppm] 0.9 0.7 0.6 0.5 0.4 0.4 0.4 0.1 0.1 120 0.4 7.2 - - melt filter Filtration accuracy of fibrous sintered body 3 2 2 2 2 2 2 2 2 2 4 2 - - membrane 3～9μm foreign matter and voids [piece/500mm ² ] 180 122 98 65 42 35 59 49 twenty two 563 223 421 Less than 10 (1.5～4.5μm) 500 (above 5μm) △ △ ○ ○ ◎ ◎ ○ ◎ ◎ ×× × ×× 3～9μm foreign matter and voids [pieces/mm ³ ] 22.5 15.3 12.3 8.1 5.3 5.8 4.7 6.1 2.8 70.4 27.9 52.6 - 9～20μm foreign matter and voids [piece/500mm ² ] 9 8 6 5 2 0 3 0 0 48 15 twenty two - 9～20μm foreign matter and voids [pieces/mm ³ ] 1.1 1.0 0.8 0.6 0.3 0.0 0.2 0.0 0.0 6.0 1.9 2.8 - Sb[ppm] 0.8 0.6 0.4 0.4 0.3 0.3 0.3 0.2 0.1 121 1.0 3.5 65 72 Thickness[μm] 16 16 16 16 16 12 25 16 16 16 16 16 16 16 Haze[%] 0.2 0.2 0.2 0.2 0.2 0.1 0.5 0.2 0.2 0.2 0.2 0.2 0.5 0.5 Optical failure evaluation happen have have without without without without without without without have have have have have Pinhole diameter [μm] 0.7 0.5 - - - - - - - 10.2 6.0 7.2 6.2 7.8

From Table 1, it was confirmed that the polyester films of Examples 1 to 9 of the present invention showed suppression of the occurrence of optical defects such as pinholes compared to Comparative Examples 1 to 3 and Reference Examples 1 to 2. The effect is better.

Furthermore, it was confirmed that when the total number of foreign matter and voids with a diameter of 3 μm or more and less than 9 μm is 100/500mm ² or less, the effect of suppressing the occurrence of optical defects is further excellent (Comparison of Examples 1 to 9) . It was confirmed that when the total number of foreign matter and voids with a diameter of 9 to 20 μm is 7/500 mm ² or less, the effect of suppressing the occurrence of optical defects is further excellent (comparison of Examples 1 to 9). It was confirmed that when the Sb content in the polyester particles is 0.8 ppm by mass or less, the effect of suppressing the occurrence of optical defects is further excellent, and when the content of Sb in the polyester particles is 0.6 ppm by mass or less, the effect of suppressing the occurrence of optical defects is particularly excellent (implementation Comparison of Examples 1 to 9). It was confirmed that when the Sb content in the polyester film is 0.7 ppm by mass or less, the effect of suppressing the occurrence of optical defects is further excellent, and when the content of Sb in the polyester film is 0.5 ppm by mass or less, the effect of suppressing the occurrence of optical defects is particularly excellent (implementation Comparison of Examples 1 to 9).

[Example 11] In the method described in "(3) Film formation" of Example 1, the following composition A as a composition for forming a particle-containing layer was applied to the surface of a longitudinally stretched polyester film, and the resulting A biaxially stretched polyester film with a thickness of 31 μm was obtained in the same manner as in Example 1, except that the film with the particle-containing layer was stretched and wound without rolling. The thickness of the particle-containing layer is 60 nm. In addition, the thickness deviation in the total length and width of the polyester film obtained by calculating the following formula based on the average value measured with an optical film thickness meter was 3.5%. Thickness deviation (%) = {6σ (thickness standard deviation)}/(thickness average) × 100

(Composition A) Composition A was prepared by mixing each component shown below. The prepared composition A was subjected to filtration treatment using a filter with a pore size of 6 μm (F20, manufactured by MAHLE Japan Ltd.) and membrane degassing (2x6 Radial Flow Super Phobic, manufactured by Polypore Co., Ltd.). ・Acid-modified polyolefin (aqueous dispersion prepared by ZAIKTHENE (registered trademark) NC, SUMITOMO SEIKA CHEMICALS CO., LTD. and adjusted to a solid content of 25% by mass by adding water): 157 parts ・Anionic hydrocarbon surfactant (RAPISOL (registered trademark) A-90, sodium di-2-ethylhexyl sulfosuccinate, manufactured by NOF CORPORATION., solid content 1 mass % water diluent): 56 parts ・Particles (SNOWTEX (registered trademark) ZL, manufactured by Nissan Chemical Corporation, colloidal silica, solid content 40 mass % aqueous dispersion): 11 parts ·Water: 776 parts

[Examples 12 to 17, Comparative Example 4] The above-mentioned composition A as a composition for forming a particle-containing layer is applied to the surface of a longitudinally stretched polyester film, and the resulting film with a particle-containing layer is stretched and wound without rolling. Except for this, a biaxially stretched polyester film having a thickness of 31 μm was obtained in the same manner as in Example 1. The thickness of the particle-containing layer is 60 nm. The thickness of the biaxially stretched polyester film was set to 31 μm, and composition A was used according to the method described in Example 11 to form a particle-containing layer with a thickness of 60 nm. Except for this, the same procedures as in Examples 2 to 5 and 8 to 9 were performed. , and the biaxially stretched polyester films of Examples 12 to 17 and Comparative Example 4 were produced in the same manner as Comparative Example 1.

[Example 18] A biaxially stretched polyester film was produced in the same manner as in Example 15 except that the thickness of the biaxially stretched polyester film was 25 μm.

[Examples 19-20] Examples 19 to 20 were produced in the same manner as in Example 11, except that polyester pellets produced from the product discharged from the third polycondensation reaction tank after the elapsed time listed in Table 1 were used. Biaxially stretched polyester film.

[Measurement of membrane] Each film produced in Examples 11 to 20 and Comparative Example 4 was analyzed using an ICP-MS analyzer in the same manner as Example 1, and the content of each element was measured. Table 2 shows the measurement results of respective Sb element contents. Moreover, in any one of Examples 11 to 20 and Comparative Example 4, the Ti content was 7 ppm, the Mg content was 75 ppm, and the P content was 65 ppm with respect to the total mass of the polyester film. In addition, the unstretched polyester films produced in Examples 11 to 20 and Comparative Example 4 did not contain inorganic particles and organic particles.

In addition, for each film produced in Examples 11 to 20 and Comparative Example 4, in the same manner as Examples 1 to 9, etc., the presence of foreign matter with a diameter of 9 to 20 μm and a diameter of 9 to 20 μm in the thickness direction of the film were measured. The total number of voids (pieces/500mm ² ), the total number of foreign matter and voids with a diameter of 3 μm or more and less than 9 μm (number/500mm ² ), and the total number of foreign matter and voids with a diameter of 9 to 20 μm per unit volume of the membrane (number /mm ³ ) and the total number of foreign objects and voids with a diameter of 3 μm or more and less than 9 μm (pieces/mm ³ ). The respective measurement results are shown in Table 2. Furthermore, in any of the films produced in Examples 11 to 20 and Comparative Example 4, foreign matter and voids having a diameter exceeding 20 μm were not observed. In addition, the haze of the films produced in Examples 11 to 20 and Comparative Example 4 was measured by the above method. The measurement results are shown in Table 2.

Table 2 below shows the film production process, the Sb content of the particles used in film production, and the above measurement results for Examples 11 to 20 and Comparative Example 4. Each mark in the table is as already explained.

[Table 2] Example 11 Example 12 Example 13 Example 14 Example 15 Example 16 Example 17 Example 18 Example 19 Example 20 Comparative example 4 Manufacturing process metal compounds Ti Ti Ti Ti Ti Ti Ti Ti Ti Ti sb Reaction tank cleaning have have have have have have have have have have have Manufactured varieties before cleaning sb sb sb sb sb Ti Ti sb sb sb sb elapsed time 72 48 72 120 216 48 216 216 60 48 216 particles Sb[ppm] 0.9 0.7 0.6 0.5 0.4 0.1 0.1 0.4 0.7 0.7 120 melt filter Filtration accuracy of fibrous sintered body 3 2 2 2 2 2 2 2 3 3 2 membrane 3～9μm foreign matter and voids [piece/500mm ² ] 313 211 186 121 66 88 35 59 325 331 988 3～9μm foreign matter and voids [pieces/mm ³ ] 20.2 13.6 12.0 7.8 4.3 5.7 2.3 4.7 26.0 26.5 63.7 9～20μm foreign matter and voids [piece/500mm ² ] 17 14 12 10 3 0 0 3 19 twenty one 88 9～20μm foreign matter and voids [pieces/mm ³ ] 1.1 0.9 0.8 0.6 0.2 0.0 0.0 0.2 1.5 1.7 5.7 Sb[ppm] 0.8 0.6 0.5 0.4 0.3 0.2 0.1 0.3 0.6 0.7 122 Thickness[μm] 31 31 31 31 31 31 31 25 31 31 31 Haze[%] 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1

[Defect evaluation] <Preparation of ceramic slurry> 100 parts by mass of barium titanate powder (BaTiO ₃ ; manufactured by Sakai Chemical Industry Co., Ltd., product name "BT-03") and polyvinyl alcohol as a binder were mixed Butyral resin (manufactured by SEKISUI CHEMICAL CO., LTD., product name "S-LEC (registered trademark) B·K BM-2") 8 Quality Department, di-n-octyl phthalate (Kanto) as plasticizer Manufactured by Chemical Co., Inc., di-n-octyl phthalate (Extra pure) 4 parts by mass and a mixture of toluene and ethanol (mass ratio 6:4) 135 parts by mass. The obtained mixture was dispersed in the presence of zirconia beads by a ball mill, and then the beads were removed from the mixture to prepare a ceramic slurry.

＜Preparation and evaluation of samples for defect measurement＞ A peeling layer (thickness 1 μm) is formed on the surface of the polyester base material side of the biaxially stretched polyester film (that is, the surface where the particle-containing layer does not exist) of the film roll around which the biaxially stretched polyester film is wound, and A release film was obtained. Here, the release layer is produced according to the method of forming a release agent layer using a release layer forming material described in Example 1 of Japanese Patent Application Laid-Open No. 2015-195291. The above-mentioned ceramic slurry is applied to the surface of the release layer of the release film with a width of 250 mm and a length of 10 m using a die coater, and then dried with a dryer at 80° C. for 1 minute so that the film thickness after drying becomes 1 μm. . The laminated film of the ceramic green sheet and the release film is irradiated with light from a fluorescent lamp from the release film side, and the light transmitted through the laminated film from the ceramic green sheet side is visually inspected over the entire surface of the formed ceramic green sheet. For defective areas such as pinholes and other surrounding areas with a different color tone, peel off the ceramic green sheet and observe the peeled film at the defective area using a transmission polarizing microscope. Count the number of defective parts (concave defects) where foreign matter is present inside the peeling film at the defective part.

Regarding the films produced in Examples 11 to 19, the number of the above-mentioned concave defects was 0. The film produced in Example 20 had two concave defects. The film produced in Comparative Example 4 had five concave defects. Based on the above, it was confirmed that the polyester films of Examples 11 to 20 of the present invention had fewer local concave defects on the ceramic green sheets than Comparative Example 4, and had a superior concave defect suppression effect.

10: Membrane manufacturing equipment 12: Reaction tank 14: Film making process department 16:Longitudinal stretching process department 18: Transverse stretching process department 20: Winding section 24:Extruder 26:Mold 28:cast drum 30:Low speed roller 32:High speed roller 34:Piping 36:Filter device 38:Piping 40: Supply port 42:Discharge outlet 44: Shell 46:Filter 48:Flow path 50:Ring member 51:Through hole 52: Sintered body 53:Porous plate 54: Spacer 56:Component F: Membrane (polyester film)

FIG. 1 is a schematic diagram showing an example of the structure of a polyester film manufacturing apparatus. FIG. 2 is a schematic cross-sectional view showing an example of the structure of a filter device used for filtering polyester resin melts. FIG. 3 is a schematic diagram showing an example of the structure of a filter included in the filtration device.

10: Membrane manufacturing equipment

12: Reaction tank

14: Film making process department

16:Longitudinal stretching process department

18: Transverse stretching process department

20: Winding section

24:Extruder

26:Mold

28:cast drum

30:Low speed roller

32:High speed roller

34:Piping

36:Filter device

38:Piping

F: Film (polyester film)

Claims (20)

A manufacturing method of polyester film, which includes: Process 1, continuously polymerizing a polyester resin precursor in the presence of a titanium compound, and measuring the antimony content of a product containing the produced polyester resin relative to the aforementioned product by inductively coupled plasma mass spectrometry. After reducing to less than 1.0 ppm by mass, polyester resin is obtained; Process 2, using a filter material containing a powdery sintered body and a filter material containing a fibrous sintered body with a filtration accuracy of 3 μm or less, to filter the melt of the polyester resin obtained in the aforementioned process 1; and Process 3: Use the melt filtered in the process 2 to produce a polyester film. The manufacturing method of polyester film as described in claim 1, wherein Before continuously polymerizing the polyester resin precursor, the inside of the reaction tank used for polymerization is cleaned. The manufacturing method of polyester film as described in claim 1 or claim 2, wherein The aforementioned polyester film has a polyester base material that does not substantially contain inorganic particles. The manufacturing method of polyester film as described in claim 1 or claim 2, wherein The aforementioned polyester resin precursor includes a diol compound and a dicarboxylic acid compound selected from the group consisting of dicarboxylic acid and dicarboxylic ester compounds. The manufacturing method of polyester film as described in claim 1 or claim 2, wherein The aforementioned polyester film contains at least one element selected from the group consisting of magnesium and phosphorus. A polyester film in which the haze is 0.6% or less, the antimony content measured by inductively coupled plasma mass spectrometry is 1 mass ppm or less, and foreign matter with a diameter of 9 to 20 μm is observed using a transmission polarizing microscope. The total number of gaps is less than 10/ ^500mm2 . The polyester film described in claim 6 is used for manufacturing dry film photoresist. The polyester film according to claim 6 or claim 7, wherein the total number of foreign matter and voids with a diameter of 3 μm or more and less than 9 μm observed using a transmission polarizing microscope is 200/500mm ² or less. A polyester film in which the total number of foreign matter and voids with a diameter of 9 to 20 μm observed under a transmission polarizing microscope is 1.7/ ^mm3 or less. The polyester film according to claim 9, which is used for manufacturing ceramic green sheets. The polyester film as claimed in claim 9 or claim 10, wherein The antimony content measured by inductively coupled plasma mass spectrometry is 1 mass ppm or less. The polyester film according to claim 9 or claim 10, wherein the total number of foreign matter and voids with a diameter of 3 μm or more and less than 9 μm observed using a transmission polarizing microscope is 27.0/mm ³ or less. The polyester film according to claim 6 or claim 9, which contains titanium, magnesium and phosphorus, The titanium content, the magnesium content, and the phosphorus content measured by inductively coupled plasma mass spectrometry are respectively 1 to 100 mass ppm relative to the total mass of the polyester film. The polyester film according to claim 6 or claim 9, which has a polyester base material that does not substantially contain inorganic particles. The polyester film according to claim 6 or claim 9, which has a polyester base material and a particle-containing layer. The polyester film as claimed in claim 6 or claim 9, wherein The thickness of the polyester film is 1 to 35 μm. The polyester film as claimed in claim 9 or claim 10, wherein The haze is 2.0% or less, and the thickness is 1 to 35 μm. A dry film photoresist having the polyester film described in any one of claims 6 to 9 and 13 to 16 and a photosensitive resin layer. The dry film photoresist as described in claim 18, wherein The aforementioned photosensitive resin layer includes a binder polymer, a polymerizable compound having an ethylenically unsaturated bond, and a photopolymerization initiator. A release film having the polyester film described in any one of claims 6 and 9 to 17 and a release layer.

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