Laminated polyester film

Abstract

The purpose of the present invention is to provide a laminated polyester film having excellent wear resistance and transparency, and excellent workability, such as workability and slippery properties when the film is wound into a roll. The present invention relates to a laminated polyester film having a functional layer on at least one surface of a polyester film, the air discharge index (mmH2O) of the surface having the functional layer being 493 mmH2O or less, and the number of bulks having a shortest diameter of 3 [mu] m or more present per 1 mm2 of the surface having the functional layer being 250 or less.

Description

Technical Field

[0001] This invention relates to laminated polyester films, and more specifically, to laminated polyester films suitable for use as ultra-fine line photoresists, exhibiting excellent transparency and slip properties, non-damaging properties, the ability to form photoresist layers with excellent resolution and surface or end patterning properties, excellent abrasion resistance and antistatic properties, and good lamination processability. Background Technology

[0002] Previously, polyester films, represented by polyethylene terephthalate and polyethylene naphthalate, have excellent properties such as mechanical strength, dimensional stability, flatness, heat resistance, chemical resistance, and optical properties, and are cost-effective, so they have been used for various applications.

[0003] One example of the use of polyester film is the film used in the dry film resist process during the manufacture of flexible printed circuit boards. Dry film resist is formed, for example, by three layers: a substrate film, a photosensitive resin layer, and a protective film. As the substrate film, a polyester film with excellent mechanical properties, optical properties, chemical resistance, heat resistance, dimensional stability, and planarity is used. In a simplified example, the protective film is first peeled off, exposing the photosensitive resin layer to a conductive substrate attached to a base plate. Next, a glass plate or film with printed circuitry (called a photomask) is pressed against the substrate film side, and light is irradiated from the photomask side. This irradiation light is generally ultraviolet light. The light passes through the transparent portions of the circuitry printed on the photomask, and the photosensitive resin reacts only in the portions exposed to ultraviolet light. The glass plate and substrate film are removed, and the unexposed portions of the photosensitive resin layer that were not exposed to ultraviolet light are removed using a suitable solvent. Furthermore, if etching is performed using an acid or the like, the photosensitive resin layer is removed, and the conductive substrate layer forms the circuitry.

[0004] Recently, due to the demand for high reproducibility and resolution in circuit pattern formation, the circuits on printed circuit boards have become extremely complex, with finer wiring and narrower spacing. In photoresist films, when the photoresist layer is exposed, as described above, light passes through the support (substrate film). Therefore, if the transparency of the support is low, problems such as insufficient exposure of the photoresist layer or resolution degradation due to light scattering will occur. Therefore, it is important that the polyester film used as the support has low haze and excellent transparency. Furthermore, if there is damage on the film surface, problems such as resolution degradation due to scattering of transmitted light will occur; therefore, it is required that the film surface be free of damage.

[0005] Polyester films with smooth surfaces, high transparency, and low haze have poor handling properties in film manufacturing and winding processes. If such film rolls are used, problems such as easy surface damage, difficulty in expelling air trapped in the film during the winding process, and wrinkles may occur.

[0006] For the polyester film used as a support, it is important to have moderate slip properties in order to ensure good processability during the manufacturing of the photoresist film to form the photoresist layer on the support, or to ensure good processability of the photoresist film itself. Furthermore, in the manufacturing of printed circuit boards, air venting is required to prevent air bubbles from entering between the support and the glass plate on which the circuit pattern is formed, thus impairing the reproducibility of the circuit pattern.

[0007] To meet these market demands, methods are used to contain particles in polyester films and form fine protrusions on the surface. To form protrusions on the film surface, numerous particle blending techniques, multilayering techniques, and techniques for combining these techniques are disclosed (for example, see Patent Documents 1-10). Furthermore, Patent Documents 3 and 4 disclose techniques for improving the processability of manufacturing polyester films for photoresist by blending antistatic agents, preventing the adhesion of dust and foreign matter, and improving the processability of the photoresist film itself.

[0008] The aforementioned techniques maintain the transparency of the film and improve its operability. In particular, the techniques in Patent Documents 3 and 4 involve containing particles only in the thin surface layer of the polyester film formed on the support and suppressing their content to a low level, resulting in extremely high transparency and antistatic properties. As a polyester film for use as an ultra-fine line photoresist, it has attracted attention for its excellent optical properties.

[0009] However, existing technologies, including this one, are designed with operability in mind, focusing on the slip properties of the film, without considering its abrasion resistance during processing. Therefore, for example, in the process of laminating a composite film with a photoresist layer stacked on top of a photoresist film onto a wiring substrate, scratches occur on the side of the composite film opposite to the surface where the photoresist layer is formed due to friction with a film holding device used to cut the composite film to the size of the wiring substrate. This scratching significantly reduces the light transmittance of the composite film and the resolution of the photoresist.

[0010] Furthermore, during this lamination process, the aforementioned film surface is damaged due to friction with the rollers used to press the composite film onto the wiring substrate, and the composite film surface becomes contaminated by resin powder generated from this damage. Therefore, there is a strong desire to develop an ultra-fine line photoresist polyester film that maintains transparency, operability, and improved abrasion resistance.

[0011] To address this issue, in Patent Document 11, a resin composition layer containing silica particles is formed on the surface of the laminated polyester film opposite to the resist layer side. By thickening the resin composition layer, the particles are prevented from falling off, thereby improving wear resistance.

[0012] Existing technical documents

[0013] Patent documents

[0014] Patent Document 1: Japanese Patent Application Publication No. 10-46012

[0015] Patent Document 2: Japanese Patent Application Publication No. 10-128930

[0016] Patent Document 3: Japanese Patent Application Publication No. 2000-221688

[0017] Patent Document 4: Japanese Patent Application Publication No. 2001-117237

[0018] Patent Document 5: Japanese Patent Application Publication No. 2002-60598

[0019] Patent Document 6: Japanese Patent Application Publication No. 2002-62661

[0020] Patent Document 7: Japanese Patent Application Publication No. 2002-72486

[0021] Patent Document 8: Japanese Patent Application Publication No. 2002-278072

[0022] Patent Document 9: Japanese Patent Application Publication No. 2002-341546

[0023] Patent Document 10: Japanese Patent Application Publication No. 2003-43691

[0024] Patent Document 11: Japanese Patent Application Publication No. 2006-327158

[0025] Patent Document 12: Japanese Patent Application Publication No. 2019-143132 Summary of the Invention

[0026] The problem the invention aims to solve

[0027] Regarding the technology in Patent Documents 1-10, as mentioned above, the use of polyester films as ultra-fine line photoresists requires further improvement in properties. In order to solve this problem, Patent Documents 11 and 12 were developed.

[0028] However, the required level of abrasion resistance has become even higher, demanding further improvements. Furthermore, as shown in Patent Document 12, there are concerns that polyester films for dry film resist substrates that substantially do not contain particles larger than 1 μm may experience film adhesion due to resist formation conditions such as ultraviolet radiation.

[0029] This invention was made against the backdrop of the aforementioned problems in the prior art. Specifically, the object of this invention is to provide a laminated polyester film with excellent abrasion resistance, transparency, ease of handling when rolled into a roll, and good slip resistance, among other processing adaptability.

[0030] Solution for solving the problem

[0031] In order to achieve the above objectives, the inventors conducted various studies and found that by producing a thin film formed from a specific composition, the above problems could be solved, thus completing the present invention.

[0032] That is, the present invention is formed by the following components. [1]

[0034] A laminated polyester film having a functional layer on at least one side of the polyester film.

[0035] The air exhaust index (mmH2O) of the surface having the aforementioned functional layer is below 493 mmH2O.

[0036] Every 1 mm of the surface having the functional layer 2 The number of coarse objects with a shortest diameter of 3 μm or more present is less than 250. [2]

[0038] The laminated polyester film according to [1] has a haze of less than 1.0%. [3]

[0040] According to the laminated polyester film described in [1] or [2], the logarithm (log(Ω / □)) of the surface resistivity (Ω / □) of at least one side of the laminated polyester film, measured at an environment of 23°C and 65%RH, is 13 or less. [4]

[0042] The laminated polyester film according to any one of [1] to [3], wherein the functional layer contains particles, the particles having a D50 of less than 1 μm,

[0043] The particle's D90 / D50 ratio is less than 3. [5]

[0045] The laminated polyester film according to any one of [1] to [4] is used as an ultrafine line photoresist. [6]

[0047] A support for an ultrafine line photoresist comprising any one of the laminated polyester films described in [1] to [4]. [7]

[0049] An ultra-fine line photoresist film comprising any one of the laminated polyester films described in [1] to [4].

[0050] The effects of the invention

[0051] The laminated polyester film of the present invention is suitable for use in ultra-fine line photoresist polyester films. This is because the present invention possesses excellent transparency, slip properties, antistatic properties, and abrasion resistance, and leaves the surface undamaged, making it suitable as a support for ultra-fine line photoresist films. Regarding photoresist films using the ultra-fine line photoresist polyester film of the present invention as a support, the resolution of the photoresist layer, the surface and end patterning properties, and the adhesion of the photoresist layer are also excellent. Furthermore, the processability and durability when manufacturing photoresist films using the ultra-fine line photoresist polyester film of the present invention as a support are excellent, resulting in excellent adhesion and abrasion resistance. Therefore, it has excellent processing adaptability such as lamination, making it useful for industrial applications.

[0052] Furthermore, since the air expulsion index of the surface with the functional layer meets the specified conditions, the air trapped inside is easily expelled when the film is wound into a roll, allowing the films to be rolled up in close contact with each other. Furthermore, for example, it can prevent deviation in the core direction during storage and transport, and can prevent damage caused by deviation. Detailed Implementation

[0053] In this specification, the phrase “contains” is intended to include the phrases “basically consists of” and “consist of”.

[0054] In this specification, regarding numerical ranges, "~" means above the value on the left and below the value on the right. For example, "0.5~10 mass%" and "0.5 mass%~10 mass%" both mean "more than 0.5 mass% and less than 10 mass%". Furthermore, regarding numerical ranges, "above" means "the same as or exceeding", and "below" means "the same as or less than".

[0055] Within the numerical ranges described in stages in this specification, the upper or lower limit of a certain stage's numerical range can be arbitrarily combined with the upper or lower limit of the numerical ranges of that stage or other stages. Furthermore, within the numerical ranges described in this specification, the upper or lower limit of the numerical range can also be replaced with the values ​​shown in the embodiments or values ​​derived unambiguously from the embodiments.

[0056] (Polyester film substrate)

[0057] The polyester film constituting the laminated polyester film of the present invention (preferably a polyester film for ultra-fine linear photoresist) (hereinafter sometimes referred to as the main layer film) is preferably a biaxially oriented polyester film with a thickness of 12 to 25 μm. Examples include films formed from polyester resins, wherein the polyester resin is mainly composed of aromatic linear polyesters such as polyethylene terephthalate and polyethylene naphthalate, which are composed of aromatic dicarboxylic acids and glycols, aliphatic linear polyesters which are composed of aliphatic dicarboxylic acids and glycols, and copolymers thereof. Among these, films formed from aromatic linear polyester resins such as polyethylene terephthalate and polyethylene naphthalate are preferred. In addition, the main layer film of the present invention can be formed from one or a mixture of two or more of the aforementioned polyester resins. The main layer film can be a single layer or a multilayer with two or more layers. The thickness of the film is preferably 12 to 25 μm, particularly preferably 13 to 20 μm, and more preferably in the range of 14 to 20 μm. If the film thickness is 12~25μm, it has good resolution, excellent strength, and is not prone to cracking during peeling operations.

[0058] The catalyst used for polycondensation in the manufacture of polyester resins is not particularly limited, but antimony trioxide is preferred because it is inexpensive and has excellent catalytic activity. Germanium compounds or titanium compounds are also preferred. Further preferred polycondensation catalysts include catalysts containing aluminum and / or its compounds with phenolic compounds, catalysts containing aluminum and / or its compounds with phosphorus compounds, and catalysts containing aluminum salts of phosphorus compounds.

[0059] In addition, the layer composition of the polyester film substrate in this invention is not particularly limited. It can be a single-layer polyester film, or a two-layer structure with different compositions, or a polyester film substrate consisting of at least three layers having an outer layer and an inner layer.

[0060] The air exhaust index (mmH2O) of at least one side of the laminated polyester film of the present invention is 493 mmH2O or less, more preferably 492 mmH2O or less, more preferably 490 mmH2O or less, and particularly preferably 488 mmH2O or less.

[0061] If the air expulsion index is below 493 mmH2O, the air trapped in the film is easily expelled when it is wound into a roll, which allows the films to come into close contact with each other and be rolled up. For example, it can prevent the film from shifting in the core direction during storage and transportation, and can prevent damage caused by shifting.

[0062] The preferred air emission index is above 450 mmH2O, for example, above 460 mmH2O, above 465 mmH2O, or above 470 mmH2O. The air emission index can be 450~493 mmH2O, 460~493 mmH2O, 465~493 mmH2O, 470~493 mmH2O, 450~492 mmH2O, 460~492 mmH2O, 465~492 mmH2O, 470~492 mmH2O, 450~490 mmH2O, 460~490 mmH2O, 465~490 mmH2O, 470~490 mmH2O, 450~488 mmH2O, 460~488 mmH2O, 465~488 mmH2O, 470~488 mmH2O, etc.

[0063] A lower air expulsion index is preferred, but if it is above 450 mmH2O, it can suppress the complete expulsion of air when the film is wound into a roll, thus increasing the film's tightness and suppressing adhesion.

[0064] Furthermore, the laminated polyester film of the present invention has a moderate air discharge index, thus enabling it to be transported and held without damaging the layer structure of the laminated polyester film.

[0065] This invention can suppress the destruction of the layer structure during storage and transport in the form of film rolls, thus enabling more uniform exposure during photoresist layer exposure. As a result, a photoresist layer with excellent resolution and pattern formation properties on the surface and ends can be formed.

[0066] In this invention, "able to suppress the destruction of the layer structure" refers to, for example, a state in which the deformation in the thickness direction of the laminated film is minimal, a state in which the thickness unevenness of the laminated film changes little before and after winding, a state in which the polyester film and the functional layer are uniformly and tightly bonded to each other without deformation, a state in which the deformation in the thickness direction of the functional layer is minimal, and a state in which the number of coarse objects described in this invention is within a specified range.

[0067] While it should not be limited to a specific theory for explanation, for example, the present invention can suppress the presence of air in the local area of ​​the film roll, and is therefore believed to be able to suppress the damage to the film's layer composition caused by the air bias during winding.

[0068] In this way, the layer composition can be maintained before and after the film is wound up. Therefore, during the exposure of the photoresist layer, uneven exposure caused by variations in the film thickness of the stacked films can be avoided, resulting in uniform exposure. Therefore, this invention is suitable for polyester films used in ultra-fine line photoresist.

[0069] The air exhaust index can be determined by the measurement method described in the embodiments below.

[0070] Regarding the method for obtaining the air exhaust index of the present invention, it can be obtained, for example, by laminating a resin composition layer on the surface opposite to the surface on which the resist layer is laminated, the resin composition layer being composed of 5 to 20% by mass of particles with an average particle size of 0.01 to 0.1 μm (a) and 0.1 to 1% by mass of 50% of particles with a volume particle size D50 of 0.3 to 1 μm (b). After the above resin composition is wet-coated, the coated surface is directly conveyed to the drying oven without being shaken on a roller, thereby enabling manufacturing to be carried out while suppressing the destruction of protrusions caused by particles.

[0071] The layer formed using the above-described resin composition layer is the functional layer of this invention.

[0072] Even after exposure of the photoresist layer, this invention can prevent damage to the layer structure during storage and transport in film roll form. Therefore, film adhesion can be suppressed after exposure, allowing for easy separation of the functional layer from the polyester film using known techniques, and also providing excellent recyclability.

[0073] The upper limit of the haze of the laminated polyester film of the present invention is preferably 1.0%, more preferably 0.9%, and even more preferably 0.8%. If it is below 1.0%, there is a tendency to obtain good resolution.

[0074] The preferred level of haze is low, ideally above 0.01% from a practical standpoint, such as above 0.05%. Haze levels can be 0.01~1.0%, 0.05~1.0%, 0.01~0.9%, 0.05~0.9%, 0.01~0.8%, 0.05~0.8%, etc.

[0075] The logarithm of the surface resistivity (Ω / □) of the layer opposite to the side where the resist layer is laminated, i.e., the functional layer of the laminated polyester film, at 23°C and 65%RH, can be 13 or less. Preferably, the logarithm of this surface resistivity is 12 or less, and more preferably 11 or less.

[0076] The logarithm of the aforementioned surface resistivity (Ω / □) can be 7 or higher, for example, 9 or higher. The logarithm of the aforementioned surface resistivity (Ω / □) can be 7~13, 9~13, 7~12, 9~12, 7~11, 9~11, etc.

[0077] By setting the logarithm of the surface resistivity to 13 or less, the increase in charge on the polyester film can be suppressed, and the processability of manufacturing the main layer film and the process of manufacturing the photoresist film using the polyester film as a support becomes better. For example, the adhesion of dust and foreign matter can be reduced, and the processability of the photoresist film itself using the polyester film for photoresist of the present invention as a support can be well maintained.

[0078] The upper limit of the static friction coefficient between one side and the opposite side of the laminated polyester film of the present invention is preferably 0.8, more preferably 0.7. By making the static friction coefficient 0.8 or less, a laminated polyester film that is less prone to damage during the winding process can be obtained. Regarding the friction coefficient, by adding particles to the functional layer, sliding properties can be imparted while maintaining transparency. The static friction coefficient is preferably small, and the friction coefficient of the laminated polyester film is typically 0.1 or higher. The static friction coefficient can be 0.1 to 0.8, 0.1 to 0.7, etc. The static friction coefficient can be measured by the measurement method of the embodiments described later.

[0079] The side of the laminated polyester film of the present invention opposite to the side where the resist layer is laminated, i.e., every 1 mm of the functional layer. 2 The number of coarse objects with a shortest diameter of 3 μm or more present in the sample is 250 or less, more preferably 200 or less, even more preferably 150 or less, and particularly preferably 100 or less.

[0080] Every 1mm of functional layer 2 When the number of coarse particles with a shortest diameter of 3 μm or more present in the photoresist layer is less than 250, the incidence of exposure defects during exposure can be reduced. The number of coarse particles can be determined by the measurement method described in the examples below.

[0081] On the other hand, every 1mm of the functional layer 2 The number of coarse objects with a shortest diameter of 3 μm or more present in the film can be 0 or more, but to meet the air exhaust index of this invention, it is preferably 5 or more, and can also be 10 or more. By satisfying this condition at the lower limit value, the film's adhesion is improved, and adhesion can be suppressed. Each 1 mm of functional layer... 2 The number of coarse objects with a shortest diameter of 3 μm or more can be 0~250, 0~200, 0~150, 0~100, 5~250, 5~200, 5~150, 5~100, 10~250, 10~200, 10~150, 10~100, etc.

[0082] A preferred embodiment of the method for imparting the aforementioned properties is as follows: A resin composition layer comprising 5-20% by mass of particles with an average particle size of 0.01-0.1 μm (a), 0.1-1% by mass of particles with a 50% volume particle size D50 of 0.3-1 μm (b), 1-3% by mass of a wax agent, and 1-10% by mass of an antistatic agent is deposited on the surface opposite to the surface where the photoresist layer is deposited. Through this embodiment, while maintaining high transparency, which is crucial for high-resolution display of the photoresist, the operability and abrasion resistance of polyester films for ultra-fine line photoresist and composite films with a photoresist layer deposited on the same film can be easily improved.

[0083] It should be noted that detailed information on the 50% volumetric particle size D50 can be found in documents such as Japanese Patent Application Publication No. 2015-174383.

[0084] The resin used to form the aforementioned resin composition layer can be any resin that is transparent, capable of fixing the aforementioned particles, waxes, antistatic agents, etc., to the surface of the polyester film, and is resistant to abrasion. However, a preferred embodiment is the selection of at least one resin from the group consisting of polyester resins, polyurethane resins, acrylic resins, amino resins, epoxy resins, and oxazoline resins. This resin can be either a commercially available product or a custom-made product with a specific composition. Furthermore, there is no limitation on the distinction between non-crosslinked and crosslinked products. There is also no limitation on the type of crosslinking agent. Additionally, the resin is used in the form of a solution or dispersion of an organic solvent or a solution or dispersion of an aqueous solvent. Particularly from the perspective of the working environment and coatability, a dispersion of an aqueous solvent, i.e., a water-dispersed resin, is preferred.

[0085] In this invention, from the perspective of maintaining transparency and improving slipability and wear resistance, the particles contained in the resin composition layer preferably use two kinds of particles with different average particle sizes.

[0086] Regarding the aforementioned particles (a), it is more preferable to contain 7 to 17% by mass of colloidal silica with an average particle size of 0.02 to 0.08 μm relative to the resin composition, and even more preferably to mix 5 to 14% by mass of colloidal silica with an average particle size of 0.03 to 0.06 μm.

[0087] The aforementioned colloidal silica is typically a colloidal dispersion formed by stably dispersing ultrafine particles of silicic anhydride (silica) in water, and is supplied to the market under brand names such as Lualox from du Pont and SNOWTEX from Nissan Chemical Corporation. Various manufacturing methods are known for these colloidal silicas, but they are usually produced using ion exchange resins. Specifically, they are produced by: forming a sol from an aqueous sodium silicate solution using a cation exchange resin, heating it to above 60°C and allowing it to mature, causing it to grow into independently dispersed particles; adding a new sol that has passed through a layer of ion exchange resin composition, thereby polymerizing and depositing the sol to increase the particle size, and producing a stabilized sol. This colloidal silica sol can be in an organic solvent system or an aqueous dispersion system. The appropriate solvent can be selected based on the solvent used for dissolving and dispersing the aforementioned resin. Furthermore, while there are substances that stabilize the sol in alkaline systems and those that stabilize it in acidic systems, this selection also depends on the type of resin and active crosslinking agent used.

[0088] The upper limit of the 50% volumetric particle size D50 of the aforementioned particles (b) is preferably 1 μm, more preferably 0.9 μm, and even more preferably 0.8 μm. If the 50% volumetric particle size D50 is less than 1 μm, it is possible to reduce the thickness of the laminated polyester film on the side opposite to the side with the resist layer per 1 mm. 2 The presence of coarse particles larger than 3 μm in the particles can improve wear resistance. The lower limit of the 50% volumetric particle size D50 is preferably 0.35 μm, more preferably 0.4 μm, and even more preferably 0.5 μm. When the 50% volumetric particle size D50 is 0.5 μm or larger, the air emission index can be reduced. The 50% volumetric particle size D50 of particle (b) can be 0.4~1 μm, 0.5~1 μm, 0.4~0.9 μm, 0.5~0.9 μm, 0.4~0.8 μm, 0.5~0.8 μm, etc.

[0089] Furthermore, the upper limit of the 90% volume particle size D90 / 50% volume particle size D50 of the aforementioned particles (b) is preferably 3. If the 90% volume particle size D90 / 50% volume particle size D50 is 3 or less, it is possible to reduce the thickness of the laminated polyester film on the side opposite to the side with the resist layer per 1 mm. 2 To reduce the amount of coarse particles larger than 3μm and to lower the air emission index. The 90% volumetric particle size D90 / 50% volumetric particle size D50 can be 1.0~3.0, 1.0~2.0, etc.

[0090] Furthermore, the aforementioned particles (b) are preferably organic particles.

[0091] The aforementioned wax is not particularly limited as long as it does not impede transparency; conventionally known substances can be used, with polymeric wax components being more preferred. Examples include polyethylene-based, polypropylene-based, and fatty acid-based waxes, with polyethylene-based waxes being particularly preferred. The weight-average molecular weight of these wax components is preferably in the range of 1,000 to 10,000, more preferably 1,500 to 6,000. When the molecular weight is less than 1,000, transfer contamination caused by exudation from the interior of the resin composition layer to the surface is easily generated; when the molecular weight exceeds 10,000, the improvement in slip properties becomes insufficient. The mixing amount of these wax components relative to the resin component is more preferably 1 to 10% by mass, more preferably 1.2 to 8% by mass, and particularly preferably 2 to 5% by mass. By mixing the aforementioned two particles of different particle sizes and the wax in the aforementioned mixing ratio into the resin component, high transparency can be maintained, and slip properties and abrasion resistance can be imparted, easily giving the polyester film, used as the aforementioned ultra-fine line photoresist, the properties required.

[0092] The aforementioned antistatic agents are compounds used to impart antistatic properties. Examples include: polymeric antistatic agents formed from polymers of one or more unsaturated monomers having sulfonate groups (e.g., sodium vinyl sulfonate, sodium methyl allyl sulfonate, sodium styrene sulfonate, ammonium vinyl sulfonate, potassium methacrylate sulfonate, lithium styrene sulfonate, etc.); and low-molecular-weight antistatic agents or their dimers containing R-SO3X (where R represents alkyl, aryl, or aromatic groups having alkyl groups, and X represents metal ions (e.g., Li, Na, K, etc.), ammonium ions, amine ions, phosphate ions, etc.). However, the aforementioned compounds are not limited to any compound that possesses sulfonate groups with excellent heat resistance and exhibits antistatic properties. For more efficient antistatic performance, low-molecular-weight antistatic agents are preferred.

[0093] Examples of alkyl sulfonates include sodium pentyl sulfonate, sodium octyl sulfonate, lithium octyl sulfonate, potassium octyl sulfonate, and sodium tetradecyl sulfonate.

[0094] In addition, examples of aryl sulfonates include sodium benzyl sulfonate, sodium toluene sulfonate, and sodium naphthyl sulfonate. Furthermore, examples of aromatic sulfonates having alkyl groups include alkyl (carbon number: 8~20) benzene sulfonate metal salts (e.g., Li, K, Na salts), sodium alkyl naphthalene sulfonate, and sodium alkyl phenyl ether disulfonate.

[0095] In addition, polymeric antistatic agents formed from polymers of unsaturated monomers having sulfonate groups are preferably styrene-based resins such as polystyrene sulfonate, which contain sulfonate groups within their molecules.

[0096] This polymeric antistatic agent is characterized by the high hydrophilicity of its sulfonic acid component. Examples of styrene-based resins containing intramolecular sulfonate groups include homopolymers of sodium, potassium, lithium, ammonium, and phosphonium salts of polystyrene sulfonate, copolymers of acrylic monomers such as acrylates or methacrylates with styrene sulfonate monomers. For example, styrene-based resins containing intramolecular sulfonate groups, such as polystyrene sulfonate, are preferred. The weight-average molecular weight of this polystyrene sulfonate is preferably 1,000 to 150,000, more preferably 10,000 to 70,000. When the molecular weight is less than 1,000, it is difficult to obtain water resistance in the coating film; when it exceeds 150,000, uniform mixing with the copolyester becomes difficult.

[0097] The preferred mixing amount of the aforementioned antistatic agent relative to the resin component is 2-9% by mass, more preferably 3-8% by mass. When the mixing amount of the antistatic agent is less than 1% by mass, the antistatic properties deteriorate, and therefore it is not preferred. Conversely, when the mixing amount of the antistatic agent exceeds 10% by mass, the antistatic property improvement effect saturates, and the antistatic agent contaminates the film manufacturing process, rollers in the processing process, etc., and therefore it is not preferred.

[0098] The aforementioned wax and antistatic agent tend to segregate on the film surface, therefore their mixing ratio affects antistatic properties, lubricity, and abrasion resistance. When the total mixing amount of the aforementioned wax and antistatic agent is set to 100% by mass, the upper limit of the wax mixing amount is preferably 80% by mass, more preferably 70% by mass, and particularly preferably 60% by mass. By keeping the antistatic agent mixing amount below 80% by mass, lubricity and abrasion resistance based on the wax can be achieved. When the total mixing amount of the aforementioned wax and antistatic agent is set to 100% by mass, the lower limit of the antistatic agent mixing amount is preferably 10% by mass, more preferably 20% by mass, particularly preferably 30% by mass, and most preferably 40% by mass. By keeping the antistatic agent mixing amount above 10% by mass, antistatic performance can be improved, and therefore this is preferred.

[0099] In this invention, a more preferred embodiment is to incorporate 0.1 to 10% by mass of an organosilicon and / or fluorine-based surfactant into the aforementioned resin composition layer. Examples of organosilicon surfactants include: dimethylsilane, aminosilane, acrylic silane, vinylbenzylsilane, vinylbenzylaminosilane, glycidylsilane, mercaptosilane, dimethylsilane, polydimethylsiloxane, polyalkoxysiloxane, hydrogen-modified siloxane, vinyl-modified siloxane, hydroxyl-modified siloxane, amino-modified siloxane, carboxyl-modified siloxane, halogen-modified siloxane, epoxy-modified siloxane, methacryloxy-modified siloxane, mercapto-modified siloxane, fluorine-modified siloxane, alkyl-modified siloxane, phenyl-modified siloxane, and epoxy-modified siloxane.

[0100] Examples of fluorinated surfactants include: tetrafluoroethylene, perfluoroalkyl ammonium salts, perfluoroalkyl sulfonamides, sodium perfluoroalkyl sulfonates, potassium perfluoroalkyl salts, perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl trimethylammonium salts, perfluoroalkyl aminosulfonates, perfluoroalkyl phosphates, perfluoroalkyl alkyl compounds, perfluoroalkyl alkyl betaines, and perfluoroalkyl halides.

[0101] The amount of the aforementioned surfactant is more preferably 0.1 to 9% by mass, and even more preferably 0.3 to 8% by mass. By mixing this surfactant, the affinity of the aforementioned resin composition layer for the main material film is improved during coating, resulting in a coating film with a good appearance.

[0102] In the aforementioned resin composition layer, a crosslinking agent is more preferably added to suppress particle shedding. Preferably, the crosslinking agent is a terminal isocyanate-based crosslinking agent or an oxazoline-based crosslinking agent. Trifunctional or higher polyisocyanates, which are precursors to terminal isocyanates, can be suitably obtained by introducing isocyanate monomers. Examples include biuret bodies, ureate bodies, and adducts modified from isocyanate monomers such as aromatic diisocyanates, aliphatic diisocyanates, aromatic aliphatic diisocyanates, or alicyclic diisocyanates having two isocyanate groups. Among these, biuret bodies are more preferably used.

[0103] Biuret bodies are self-condensing compounds formed by the self-condensation of isocyanate monomers, such as biuret bodies of hexamethylene diisocyanate.

[0104] Urea esters are trimers of isocyanate monomers, such as trimers of hexamethylene diisocyanate, isophorone diisocyanate, and toluene diisocyanate.

[0105] An adduct is an isocyanate compound with trifunctional or higher functions formed by reacting an isocyanate monomer with a low-molecular-weight compound containing active hydrogen. Examples include compounds formed by reacting trimethylolpropane with hexamethylene diisocyanate, compounds formed by reacting trimethylolpropane with toluene diisocyanate, compounds formed by reacting trimethylolpropane with phenylenediamine diisocyanate, and compounds formed by reacting trimethylolpropane with isophorone diisocyanate.

[0106] Without impairing the effects of the present invention, the aforementioned resin composition layer may contain known additives, such as antioxidants, heat stabilizers, weather stabilizers, and organic lubricants.

[0107] In this invention, it is important to maintain high transparency while imparting slip properties and abrasion resistance. Therefore, during coating liquid preparation, it is more preferable to manage the temperature of the raw materials before preparation to prevent particle aggregation caused by temperature differences between the materials during mixing. Furthermore, it is even more preferable to add each material while continuously stirring the coating liquid tank during preparation. Moreover, it is a preferred embodiment to install a filter in front of the coating apparatus to remove micro-aggregates contained in the raw materials before preparation or generated during preparation due to component aggregation.

[0108] In this invention, the method of laminating the aforementioned resin composition layer is not limited. A preferred embodiment is to laminate the resin composition layer onto an unstretched or uniaxially stretched film during the polyester film manufacturing process, i.e., by online coating. Online coating improves the adhesion and adhesion durability between the main material film and the aforementioned resin composition layer. Furthermore, it offers excellent economic benefits and is therefore preferred.

[0109] As a method for setting the aforementioned resin composition layer, commonly used methods such as gravure coating, kiss coating, immersion coating, spraying, curtain coating, air knife coating, scraper coating, and reverse roller coating can be applied.

[0110] In this invention, it is important to maintain high transparency while imparting slip properties and abrasion resistance. Therefore, it is crucial to suppress the aggregation of particles in the coating liquid that forms the aforementioned resin composition layer. For example, if the liquid temperature of the coating liquid decreases, the aggregation of these particles increases. On the other hand, as the liquid temperature of the coating liquid increases, wettability deteriorates; therefore, extremely strict temperature management within ±1°C is also a preferred embodiment. By implementing such an embodiment, the high quality of the laminated polyester film of this invention can be stabilized and maintained.

[0111] The thickness of the aforementioned resin composition layer is not particularly limited. In this invention, the final thickness after drying is preferably 0.01~0.2 μm, more preferably 0.015~0.16 μm, and even more preferably 0.02~0.12 μm. When the thickness is 0.01 μm or more, the improvement effect on sliding properties and wear resistance is enhanced; conversely, when the thickness is 0.2 μm or less, the transparency decreases, and therefore it is not preferred.

[0112] In this invention, when the aforementioned resin composition layers are stacked, the stacked polyester film is given sliding properties and abrasion resistance. Therefore, from the perspective of transparency, it is not necessary for the film of the aforementioned main layer to contain particles.

[0113] It should be noted that the aforementioned "the main layer film does not need to contain particles" refers to the absence of actively contained particles, not that the resulting film is completely free of particles. This is because, even without actively adding particles to the film, contaminants from foreign matter, or dirt from the production line or equipment during the manufacturing process of the raw resin or film, can sometimes be shed and mixed into the film. For example, regarding the particle content in the resulting film, in the case of inorganic particles, if the content is below 50 ppm, preferably below 10 ppm, and most preferably below the detection limit when quantifying inorganic elements by fluorescence X-ray analysis, it is considered substantially free of particles.

[0114] Therefore, the following lamination configuration is a preferred embodiment of the present invention: in order to make the haze of the laminated film less than 1.0%, the polyester film of the support body and the biaxially stretched polyester film of the main layer are substantially free of particles, and the resin composition layer laminated in the support body only contains particles on the side opposite to the main layer film of the laminated resist layer.

[0115] Therefore, in the aforementioned preferred embodiment, it is not necessary to form a functional layer for imparting sliding properties, etc., on the surface of the main layer film where the resist layer is stacked. The effects of the present invention can be more significantly demonstrated without employing such a method, and therefore it is recommended. However, methods that include particles in the main layer film serving as the support, or methods that stack a functional layer on the surface where the resist layer is formed, are not excluded as long as they do not impair the effects of the present invention.

[0116] Regarding damage to the film surface, in addition to taking measures to prevent damage generated in the aforementioned processing steps, damage generated during the manufacturing process of the film, which serves as the main layer, also needs to be fully considered. For example, if the surface roughness of rollers such as the applicator roller in the coating process is large, damage will occur. Therefore, setting the surface roughness of such rollers to 0.2S or less is a preferred embodiment. Furthermore, in order to prevent the accumulation of damage-causing factors such as deposits, attachments, and foreign matter on the roller surface, installing roller cleaners on the preheating inlet and cooling roller in the longitudinal stretching process is also a preferred embodiment.

[0117] In addition, there is a method to set the cleanliness level in the aforementioned film manufacturing process to level 1,000 or less (1,000 or less particles larger than 0.5 μm per cubic foot of volume), and in particular, it is preferred to use clean air of level 100 or less around the roller and to use air of level 100 or less for the air supply cooling device used to cool the opposite side of the roller in the casting process.

[0118] In addition, in the film manufacturing process, it is also a preferred implementation method to reduce the speed difference between the film and the roller as much as possible by precisely controlling the speed of the roller through which the film passes, and to take countermeasures to prevent damage caused by friction.

[0119] Furthermore, methods for cleaning the rollers before the aforementioned film manufacturing process, such as using abrasive materials to remove defects on the rollers, can also be cited. Additionally, to prevent the film from attracting dust and other contaminants due to static electricity, methods can be used to install a static eliminator so that the film's charge is ±1500V or less throughout the entire process. The process from casting the main layer of the film, which serves as the support, to the tenter frame (described later) is the main process prone to damage; therefore, a compact layout of this section, with a throughput time of 5 minutes or less, helps to suppress defect formation and is therefore preferable.

[0120] Example

[0121] Next, the present invention will be described in detail using examples and comparative examples, but the present invention is not limited to the following examples. First, the evaluation method used in the present invention will be described below.

[0122] The following examples illustrate the effectiveness of the present invention, but the invention is not limited to these examples. It should be noted that the methods for evaluating the physical properties in the following examples are described below.

[0123] (1) D50 and D90 of particles

[0124] The particle size distribution was measured using a laser diffraction particle size distribution measuring device, SALD-7500nano (manufactured by Shimadzu Corporation). Before measurement, particles were weighed at a concentration equivalent to 0.2% by mass of slurry, using ion-exchanged water as the solvent. The particles were stirred for 10 minutes using a mixer (e.g., a National MXV253 cooking mixer), cooled to room temperature, and then measured using a high-concentration measurement unit. Regarding the refractive index, the refractive index of the type with the highest mass percentage among the inorganic particles used was referenced from the device's built-in database to calculate the particle size. Based on the particle size distribution measurement results, the 50% volumetric particle size (D50) and 90% volumetric particle size (D90) were calculated, and the D90 / D50 ratio was then calculated.

[0125] (2) Resin composition layer thickness

[0126] The film cross-section was cut into ultrathin sections, and observed and photographed using TEM (transmission electron microscopy) via a staining ultrathin section method employing RuO4 staining, OsO4 staining, or a double staining of both. The thickness of the resin composition layer was measured from the obtained film cross-section photographs. The resin composition layer thickness was calculated as the average of 30 measurements taken within the field of view.

[0127] (3) Air Exhaust Index

[0128] The test was conducted according to JIS P 8155:2010 "Paper and paperboard - Test method for smoothness - O-Ken method". The O-Ken smoothness tester used was a device manufactured by Kumagai Riki Kogyo Co., Ltd. (Product No. 2040-C). The aforementioned JIS specifies a pressure of 98.1 ± 1.0 kPa applied to the test piece; however, directly applying this pressure to the film makes it difficult to reproduce the air expulsion characteristics during film winding. Therefore, the authors conducted in-depth research and confirmed that by setting the pressure applied to the test piece to 48 kPa ± 1.0 kPa and the measurement time to 150 seconds, the air expulsion characteristics during film winding could be accurately reproduced. The measured water column value (mmH2O) was used as the air expulsion index.

[0129] (4) Static friction coefficient

[0130] The measurements were performed according to JIS K 7125. The load sensor was directly connected to the sample without a spring; the mass of the sliding plate was 4.4 kgf; and the test speed was 200 mm / min. For each sample, three measurements were taken, and the average value was used as the static friction coefficient.

[0131] (5) Large quantities of material with a shortest diameter of 3 μm or more

[0132] A 6cm × 6cm sample was taken from a laminated polyester film. For each sample, a scanning white interference microscope (device: Hitachi High-Tech Corporation "VertScan" (registered trademark) VS1540) was used with a 10x objective lens to measure the surface of the laminated polyester film opposite to the side with the resist layer, with a measurement area of ​​936μm × 702μm. Regarding sample setup, the sample was placed on the stage with the Y-axis as the length direction of the sample film (the direction of film winding). It should be noted that when the length direction of the sample is unknown, measurements were taken with the Y-axis as any direction of the sample film, then measured in a direction rotated by 120 degrees, and then again in a direction rotated by 120 degrees. The average of these measurements was used as the number of protrusions in the sample. Furthermore, for the sample film being measured, the film was clamped between two metal frames fitted with rubber pads to create a taut state within the frames (a state where the sample is relaxed and curling is eliminated) for surface measurement.

[0133] For the obtained microscope images, image processing was performed using the surface analysis software VS-ViewerVersion 10.0.3.0 built into the microscope under the following conditions to determine the number of protrusions at each height.

[0134] (Image processing conditions)

[0135] Perform image processing in the following order.

[0136] • Interpolation processing: Full interpolation

[0137] • Filtering: Gaussian (cutoff 100)

[0138] • Surface correction: 4 times

[0139] Furthermore, particle analysis was performed under the following conditions, and the number of particles displayed in the "Particle Analysis" screen, detected at a height threshold of 25 nm (height threshold setting: 0.025 μm), was used as the amount of coarse material with a minimum diameter of 3 μm or more.

[0140] (Particle analysis conditions)

[0141] Protrusion analysis was performed under the following conditions.

[0142] • Type of analysis: Protrusion analysis

[0143] • Image correction: None

[0144] ·deal with

[0145] • Height threshold: 0.025μm

[0146] • Reference height: Zero plane (average plane)

[0147] The same procedure was performed on all 36 fields of view used in the measurements. The total number of particles with a minimum diameter greater than 3 μm was calculated and divided by the measurement area of ​​the 36 fields of view (0.657 mm²). 2 From this, the number of coarse particles larger than 3μm (number / mm) can be calculated. 2 ).

[0148] (6) Antistatic properties (surface resistivity)

[0149] The film was cut into 5cm × 10cm pieces and dried for 24 hours at 23°C and 65% RH. Then, to determine the antistatic properties of the surface of the film with the laminated resin composition layer, a surface resistivity meter (Mitsubishi Yuka Co., Ltd.) was used to measure the surface resistivity (Ω / □) under an applied voltage of 500V, a temperature of 23°C, and a humidity of 65% RH, expressed logarithmically (log(Ω / □)). This measurement was performed on five randomly selected samples, and the average of the five measurements was calculated.

[0150] (7) Abrasion resistance (abrasion resistance index)

[0151] A vibration-type friction fastness tester (manufactured by Yamaguchi Scientific & Industrial Co., Ltd.) was used to apply friction to the resin layer surface of a sample with a width of 3 cm and a length of 20 cm under a load of 500 gf and 40 cycles. Aluminum foil was used as the test object, and the machinability of the resin composition layer was evaluated by observing the surface of the aluminum foil after the friction was applied, with three grades.

[0152] ◎: No particle transfer was observed on the aluminum foil.

[0153] 〇: Slight particle transfer was observed on the aluminum foil.

[0154] ×: A large number of particles were observed transferred on the aluminum foil.

[0155] (8) Film roll winding offset

[0156] The sample film was wound into a roll of 1000m and the resulting film roll was observed. A roll without any film roll offset was rated as 0, a roll with slight offset as △, and a roll with significant offset as ×.

[0157] (9) Haze

[0158] According to JIS K 7136-2000 "Method for determining the haze of plastics-transparent materials", the haze was measured using a turbidimeter (Nippon Denshoku Kogyo Co., Ltd., NDH2000).

[0159] Preparation of an aqueous dispersion (C-1WD) of a capped isocyanate-based crosslinking agent (C-1)

[0160] In a flask equipped with a stirrer, thermometer, and reflux condenser, 125.2 parts by weight of a biuret-structured polyisocyanate compound (manufactured by Asahi Kasei Chemicals Corporation, Durnate 24A-100, NCO concentration 23.1%), based on hexamethylene diisocyanate, 50.0 parts by weight of dipropylene glycol dimethyl ether, and 68.8 parts by weight of 3,5-dimethylpyrazole were added. The mixture was stirred at 70°C under a nitrogen atmosphere for 2 hours. The infrared spectrum of the reaction solution was then measured to confirm the disappearance of the isocyanate group absorption. Next, after cooling to room temperature, 6 parts by weight of polyethylene glycol (n=12) monolaurate were added, and the mixture was stirred at 2000 min... -1 Water was added while stirring and mixing. The concentration was adjusted by water to prepare an aqueous dispersion (C-1WD) of 30.0% by mass of the end-capped isocyanate crosslinking agent (C-1).

[0161] (Example 1)

[0162] (1) Adjustment of coating solution

[0163] The following coating agent is mixed in a mixed solvent of water and isopropanol to prepare a coating solution.

[0164] 8.00 parts by weight of polyester aqueous dispersion

[0165] (Made by Toyobo Corporation, VYLONAL MD1200, solids content 30% by mass)

[0166] 1.00 parts by weight of granules (a)

[0167] (SNOWTEX OL manufactured by Nissan Chemical Co., Ltd., colloidal silica with an average particle size of 0.045 μm, solid content concentration of 20% by mass)

[0168] Particles (b) 1.50 parts by weight

[0169] (Acrylic particles with D50 of 0.57 μm and D90 / D50 of 1.3, solid content concentration 2% by mass)

[0170] 0.50 parts by weight of surfactant

[0171] (Organosilicon-based, solid content 10% by mass)

[0172] 0.80 parts by weight of wax

[0173] (High-Tech E9015 manufactured by Toho Chemical Industry Co., Ltd., 20% solids concentration)

[0174] 0.80 parts by weight of antistatic agent

[0175] (Alkyl sulfonate TB214, solids concentration 16.7%)

[0176] (2) Manufacturing of laminated polyester film

[0177] As a polymer feedstock for the film, PET resin granules with an intrinsic viscosity (solvent: phenol / tetrachloroethane = 60 / 40) of 0.62 dl / g and substantially free of particles were dried at 135°C for 6 hours under reduced pressure of 133 Pa. The dried granules were then fed to an extruder and melt-extruded into sheets at approximately 280°C. These sheets were then rapidly cooled and solidified on rotating cooling metal rollers with a surface temperature maintained at 20°C to obtain unstretched PET sheets.

[0178] The unstretched PET sheet is heated to 100°C using a heated roller assembly and an infrared heater, and then stretched 3.5 times along its length using a roller assembly with a circumferential speed difference to obtain a uniaxially stretched PET film.

[0179] Next, the aforementioned coating solution, which had been allowed to stand at room temperature for more than 5 hours, was applied to one side of a PET film using a roller coating method. Then, the film was stretched 4.0 times its original width at 120°C using a tenter frame. With the width length of the film fixed, it was heated at 230°C for 5 seconds, followed by a 3% width relaxation treatment at 100°C for 10 seconds, resulting in a 16 μm thick laminated polyester film. The evaluation results of this film are shown in Table 1. It should be noted that the final (after biaxial stretching) dried coating weight is 0.05 g / m². 2 The adjustment was made in the manner of (50nm thickness of the functional layer after drying).

[0180] (Example 2)

[0181] The particles (b) were changed to polystyrene particles with a D50 of 0.70 μm and a D90 / D50 of 1.3 (solid content concentration of 2%), and the amount of particles (b) added was changed to 1.25 parts by mass. Otherwise, the same procedure as in Example 1 was followed to obtain a laminated polyester film.

[0182] (Example 3)

[0183] The particles (b) were changed to acrylic particles with a D50 of 0.73 μm and a D90 / D50 of 1.2 (solid content concentration of 2%), and the amount of particles (b) added was changed to 0.75 parts by mass. Otherwise, the operation was the same as in Example 1 to obtain a laminated polyester film.

[0184] (Example 4)

[0185] The following coating agent was mixed in a mixed solvent of water and isopropanol, otherwise a laminated polyester film was obtained in the same manner as in Example 1.

[0186] 8.00 parts by weight of polyester aqueous dispersion

[0187] (Made by Toyobo Corporation, VYLONAL MD1200, solids content 30% by mass)

[0188] Crosslinking agent C-1WD 0.80 parts by weight

[0189] (30% by mass of solid components)

[0190] 1.00 parts by weight of granules (a)

[0191] (SNOWTEX OL manufactured by Nissan Chemical Co., Ltd., colloidal silica with an average particle size of 0.045 μm, solid content concentration of 20% by mass)

[0192] Particles (b) 1.50 parts by weight

[0193] (Acrylic particles with D50 of 0.57 μm and D90 / D50 of 1.3, solid content concentration 2% by mass)

[0194] 0.50 parts by weight of surfactant

[0195] (Organosilicon-based, solid content 10% by mass)

[0196] 0.80 parts by weight of wax

[0197] (High-Tech E9015 manufactured by Toho Chemical Industry Co., Ltd., 20% solids concentration)

[0198] 0.80 parts by weight of antistatic agent

[0199] (Alkyl sulfonate TB214, solids concentration 16.7%)

[0200] (Example 5)

[0201] The particles (b) were changed to polystyrene particles with a D50 of 0.31 μm and a D90 / D50 of 1.5 (solid content concentration of 2%), and otherwise operated in the same manner as in Example 1 to obtain a laminated polyester film.

[0202] (Example 6)

[0203] The particles (b) were changed to silica particles with a D50 of 0.80 μm and a D90 / D50 of 2.8 (solid content concentration of 2%), and the amount of particles (b) added was changed to 0.75 parts by mass. Otherwise, the operation was the same as in Example 1 to obtain a laminated polyester film.

[0204] (Comparative Example 1)

[0205] The particles (b) were replaced with silica particles (solid content concentration of 2%) with a D50 of 0.28 μm and a D90 / D50 of 1.7. Otherwise, the same procedure as in Example 1 was followed to obtain a laminated polyester film.

[0206] (Comparative Example 2)

[0207] The particles (b) were changed to silica particles with a D50 of 0.93 μm and a D90 / D50 of 3.2 (solid content concentration of 2%), and the amount of particles (b) added was changed to 0.75 parts by mass. Otherwise, the operation was the same as in Example 1 to obtain a laminated polyester film.

[0208] (Comparative Example 3)

[0209] The particles (b) were changed to silica particles with a D50 of 1.46 μm and a D90 / D50 of 3.8 (solid content concentration of 2%), and the amount of particles (b) added was changed to 0.75 parts by mass. Otherwise, the operation was the same as in Example 1 to obtain a laminated polyester film.

[0210] (Comparative Example 4)

[0211] The particles (b) were changed to silica particles with a D50 of 2.36 μm and a D90 / D50 of 2.2 (solid content concentration of 2%), and the amount of particles (b) added was changed to 0.75 parts by mass. Otherwise, the operation was the same as in Example 1 to obtain a laminated polyester film.

[0212] Table 1 summarizes the evaluation results of each embodiment and comparative example.

[0213] [Table 1]

[0214]

[0215] The present invention exhibits preferred results in all aspects of air exhaust index, static friction coefficient, amount of coarse material (number of coarse protrusions) with a shortest diameter of 3 μm or more, antistatic properties, wear resistance, and film roll-up offset.

[0216] That is, the present invention is suitable as a support for ultra-fine line photoresist films.

[0217] Furthermore, the photoresist film using the ultra-fine line photoresist polyester film of the present invention as a support exhibits excellent resolution, surface and end pattern formation properties, and adhesion of the photoresist layer. Moreover, the processability and durability of the photoresist film manufactured using the ultra-fine line photoresist polyester film of the present invention as a support, such as adhesion and abrasion resistance, are excellent, thus providing excellent adaptability to processing such as lamination, making it useful for industrial applications.

[0218] On the other hand, the air discharge index of Comparative Example 1 is outside the scope of the present invention, and film roll-up shift occurs. In Comparative Examples 2 and 3, the number of coarse particles larger than 3 μm is outside the scope of the present invention, and the wear resistance does not meet the required characteristics.

[0219] In Comparative Example 4, the number of coarse particles larger than 3 μm is outside the scope of this invention, and the wear resistance does not meet the required characteristics. Furthermore, the surface has many uneven areas, making it unsuitable for the production of extremely fine line photoresist.

[0220] Industrial availability

[0221] The polyester film for ultra-fine line photoresist of the present invention possesses excellent transparency, slip properties, antistatic properties, and abrasion resistance, making it suitable as a support for ultra-fine line photoresist films. Photoresist films using the polyester film for ultra-fine line photoresist of the present invention as a support exhibit excellent resolution, surface and end patterning properties, and adhesion of the photoresist layer. Furthermore, using the polyester film for ultra-fine line photoresist of the present invention as a support also provides excellent processability and durability, such as anti-adhesion and abrasion resistance during photoresist film manufacturing, thus enabling its use in applications such as lamination, demonstrating excellent processing adaptability. Therefore, the polyester film of the present invention is particularly suitable as a support for ultra-fine line photoresist. Additionally, the technical concept of the present invention can also be applied to other industrial films, such as substrate films for optical functional films requiring high transparency. Therefore, the present invention is beneficial to the industry.

Claims

1. A laminated polyester film having a functional layer on at least one side of the polyester film, The air exhaust index (mmH2O) of the surface having the aforementioned functional layer is below 493 mmH2O. Every 1 mm of the surface having the functional layer 2 The number of coarse objects with a shortest diameter of 3 μm or more present is less than 250.

2. The laminated polyester film according to claim 1 has a haze of less than 1.0%.

3. The laminated polyester film according to claim 1, wherein, The surface resistivity of at least one side of the laminated polyester film, measured at an environment of 23°C and 65%RH, has a logarithm of less than 13. The unit of the surface resistivity is Ω / □, and the logarithm is log(Ω / □).

4. The laminated polyester film according to claim 1, wherein, The functional layer contains particles, and the D50 of the particles is less than 1 μm. The particle's D90 / D50 ratio is less than 3.

Images