JP2023111665A - laminated polyester film - Google Patents

Abstract

To provide a laminated polyester film which is excellent in handleability when being wound in a roll shape due to formation of a fine uneven structure.SOLUTION: A laminated polyester film has a polyester film and a resin layer formed on at least one surface of the polyester film using a resin composition, and satisfies all of the following requirements (1) to (4). (1) The resin layer has an uneven structure. (2) The resin composition contains the following compounds (A) and (B): (A) one or more selected from the group consisting of a binder resin and a crosslinking agent, and (B) particles. (3) A ratio of the content of the particles (B) occupying in the total non-volatile component in the resin composition is 20 mass% or more. (4) Kurtosis (Sku) of the surface of the resin layer is less than 3.0.SELECTED DRAWING: None

Description

The present invention relates to laminated polyester films.

Polyester films represented by polyethylene terephthalate film and polyethylene naphthalate film have excellent mechanical properties, dimensional stability, flatness, heat resistance, chemical resistance, optical properties, etc., and are excellent in cost performance. are used for various purposes.

In addition, by utilizing the smoothness of the film surface, polyester film is used in various applications such as release films for molding green sheets of laminated ceramic capacitors, base materials for releasing interlayer insulating resins, and base materials for dry film resists. It is suitable for use.

A sheet-forming polyester film having excellent surface smoothness, including the above applications, is required to have no wrinkles and a good roll appearance when wound into a roll.
However, if the surface smoothness is increased, the slipperiness is lowered, and the air escape during winding into a roll or unwinding from the roll is deteriorated, so that winding misalignment or blocking occurs, resulting in poor handling.
In particular, in recent years, along with the improvement of productivity, there is a tendency for polyester films to become thinner and longer, and roll appearance quality at a higher level is required.

Therefore, in order to ensure handleability, the non-smooth side (back side) is sometimes designed to be rougher than the smooth side by kneading particles (for example, Patent Document 1).
In addition, Patent Document 2 discloses a slippery composite polyester film in which a continuous coating layer having a fine mesh uneven structure is provided on at least one side of the polyester film for the purpose of improving handling properties.

JP 2015-33811 A Japanese Patent Application Laid-Open No. 2000-211082

However, in the conventional method for producing a particle kneaded film as disclosed in Patent Document 1, it is difficult to control the formation of unevenness and it is difficult to form a fine uneven structure, and the film disclosed in Patent Document 2 has unevenness. is insufficient, wrinkles tend to occur when wound into a roll, and the appearance of the roll may be impaired.

Therefore, the present invention has been made in view of the above-mentioned circumstances, and the problem to be solved is to provide a laminated polyester film that has excellent handleability when winding the film into a roll by forming a fine uneven structure. That is.

As a result of intensive studies, the inventors have found that the above problems can be solved by having the following configuration.
The present invention has the following aspects.

[1] A laminated polyester film comprising a polyester film and a resin layer formed of a resin composition on at least one side of the polyester film, wherein the laminate satisfies all of the following requirements (1) to (4): polyester film.
(1) The resin layer has an uneven structure.
(2) The resin composition contains the following compounds (A) and (B).
(A) one or more selected from the group consisting of a binder resin and a cross-linking agent; (B) particles; % by mass or more.
(4) Kurtosis (Sku) of the surface of the resin layer is less than 3.0.
[2] The laminated polyester film according to [1] above, wherein the resin layer surface has an arithmetic mean roughness (Ra) of 10 nm or more when measured with a scanning probe microscope.
[3] The laminated polyester film according to [1] or [2] above, wherein the resin layer surface has a ten-point average roughness (Rzjis) of 60 nm or more when measured with a scanning probe microscope.
[4] The above [1]-[ 3]. The laminated polyester film according to any one of 3].
[5] The laminated polyester film according to any one of [1] to [4] above, wherein the resin layer surface has a root-mean-square gradient (Sdq) of 0.1 or more.
[6] The laminated polyester film according to any one of [1] to [5] above, wherein the resin layer surface has a developed interface area ratio (Sdr) of 0.5% or more.
[7] The laminated polyester film of any one of [1] to [6] above, which has an air leakage index of 130,000 seconds or less.
[8] The laminated polyester film as described in any one of [1] to [7] above, wherein the particles (B) have an average particle size of 1 to 100 nm.
[9] The above-mentioned [1] to [8], wherein the (A) binder resin contains one or more selected from the group consisting of polyester resins, (meth)acrylic resins and polyurethane resins. Laminated polyester film.
[10] The laminated polyester film according to any one of [1] to [9] above, wherein the particles (B) contain one or more selected from the group consisting of zirconium oxide, titanium oxide and silica.

ADVANTAGE OF THE INVENTION According to this invention, the laminated|multilayer polyester film excellent in the handleability at the time of winding a film into a roll form is provided by formation of fine unevenness|corrugation structure.

In addition, the laminated polyester film of the present invention can form a fine uneven structure on the surface of the resin layer. There is an advantage that it exerts the property and wrinkles are less likely to occur.

Furthermore, since the resin layer of the laminated polyester film of the present invention can be made into a thin film, the polyester film can be made thin and long, and it can contribute to productivity improvement by reducing the frequency of switching product rolls during processing. can.

1 is an image obtained by observing the surface of a resin layer of Example 1. FIG. 11 is an image obtained by observing the resin layer surface of Example 8. FIG. It is an image which observed the resin layer surface of Example 19. FIG.

Next, an example of an embodiment of the invention will be described. However, the present invention is not limited to the embodiments described below.

In this specification, when the expression "(meth)acryl" is used, "(meth)acryl" means one or both of "acryl" and "methacryl". Similarly, "(meth)acrylic acid" is one or both of "acrylic acid" and "methacrylic acid", "(meth)acrylate" is one or both of "acrylate" and "methacrylate", "(meth)acryloyl ” shall mean one or both of “acryloyl” and “methacryloyl”. Others are the same as above.

<<<Laminated Polyester Film>>>
The laminated polyester film of the present invention (hereinafter also referred to as "this laminated polyester film") comprises a polyester film (hereinafter also referred to as "this polyester film") and a resin formed on at least one side of the polyester film from a resin composition. layer (hereinafter also referred to as "this resin layer").

The laminated structure of the present laminated polyester film may be a structure in which a resin layer is formed on one side of the polyester film and the surface of the polyester film is left as it is on the other side. It may be a configuration formed by forming a layer of
Moreover, the structure formed by forming a resin layer on both surface sides of a polyester film may be sufficient.
Furthermore, the resin layer may be formed directly on the polyester film, or another layer may be provided between the polyester film and the resin layer.

<<polyester film>>
The present polyester film serves as a base material for the present laminated polyester film. The present polyester film may have a single layer structure or a multilayer structure. When the present polyester film has a multi-layer structure, the present polyester film may have a two-layer structure, a three-layer structure, or the like, or may have a multilayer structure of four or more layers as long as it does not deviate from the gist of the present invention. It is not particularly limited.
When the present polyester film has a multi-layer structure of two or more layers, it is particularly preferable to have two kinds of three layers or three kinds of three layers. When the present polyester film has a multilayer structure, it is also preferable to have a structure in which surface layers are provided on both sides of an intermediate layer.

In particular, when utilizing the smoothness of the laminated polyester film, it is preferable that at least one side of the polyester film has excellent smoothness. Such a design method includes, for example, a method of designing the present polyester film as a single layer, a 2-kind 3-layer structure, and a 3-kind 3-layer structure so that both surfaces of the polyester film are designed to have excellent smoothness, and the present polyester film is a three-layered structure of three types, one surface of the present polyester film is in a state of excellent smoothness, and the other surface is designed to have different roughness.

Further, the present polyester film may be a non-stretched film (sheet) or a stretched film. Among them, stretched films uniaxially or biaxially stretched are preferred. Among them, a biaxially stretched film is more preferable in terms of excellent balance of mechanical properties and flatness.

<Polyester>
The polyester, which is the raw material of the present polyester film, refers to a polymer compound having continuous ester bonds in the main chain, and may be a homopolyester or a copolymer polyester. Specifically, a polyester obtained by subjecting a dicarboxylic acid component and a diol component to a polycondensation reaction can be mentioned. Moreover, it is preferable to use a polyester containing more than 50 mol % of an aromatic dicarboxylic acid or an aliphatic dicarboxylic acid when the dicarboxylic acid component is taken as 100 mol %.

Examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, Aromatic dicarboxylic acids such as 4,4'-diphenyletherdicarboxylic acid and 4,4'-diphenylsulfonedicarboxylic acid, such as adipic acid, suberic acid, sebacic acid, dimer acid, dodecanedioic acid, cyclohexanedicarboxylic acid and their esters Mention may be made of aliphatic dicarboxylic acids such as derivatives.

Examples of the diol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1 ,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-hexanedimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol, 2,2-bis(4-hydroxyethoxy phenyl)propane, isosorbate and spiroglycol, and the like.

When the polyester is a homopolyester, it is preferably obtained by polycondensation of an aromatic dicarboxylic acid and an aliphatic diol. Preferred aromatic dicarboxylic acids include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and preferred aliphatic diols include ethylene glycol, diethylene glycol and 1,4-cyclohexanedimethanol. Representative homopolyesters include polyethylene terephthalate (PET), polyethylene-2,6-naphthalenedicarboxylate (PEN), etc., with polyethylene terephthalate being preferred.

On the other hand, the copolyester is preferably a polycondensation polymer of, for example, a dicarboxylic acid component and an aliphatic diol. As the dicarboxylic acid component, preferably one or two of isophthalic acid, phthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, sebacic acid and oxycarboxylic acid (e.g., p-oxybenzoic acid, etc.) species or more. As the aliphatic diol, one or more of ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol and the like are preferably used. The copolymer polyester preferably contains terephthalic acid as the dicarboxylic acid component and ethylene glycol as the aliphatic diol.
When the above polyester is a copolymerized polyester, it is preferably a copolymer containing 30 mol % or less of the third component. The third component is a compound other than the compound that is the main component of the dicarboxylic acid component that constitutes the polyester (that is, the component that has the highest content) and the compound that is the main component of the diol component. For example, copolymerized polyethylene terephthalate are components other than terephthalic acid and ethylene glycol.
The copolyester may also contain a structural unit derived from a bifunctional compound other than the dicarboxylic acid component and the aliphatic diol. Structural units derived from bifunctional compounds other than dicarboxylic acid components and aliphatic diols are preferably 20 mol % or less, more preferably 10 mol % or less, relative to the total mol of all structural units constituting the polyester. Bifunctional compounds include various hydroxycarboxylic acids, aromatic diols, and the like.

The content of terephthalic acid in all dicarboxylic acid components constituting the present polyester film is preferably 50 mol % or more, more preferably 70 mol % or more, still more preferably 90 mol % or more.
In addition, the content of ethylene glycol in all diol components constituting the present polyester film is preferably 50 mol % or more, more preferably 70 mol % or more, still more preferably 90 mol % or more.
In addition, the upper limit of the content of terephthalic acid and ethylene glycol is 100 mol %.

Further, the polyester may be a recycled polyester or a biomass-derived polyester.

<Polycondensation catalyst>
The polycondensation catalyst for polycondensing the above polyester is not particularly limited, and conventionally known compounds can be used, for example, titanium compounds, germanium compounds, antimony compounds, manganese compounds, aluminum compounds, magnesium compounds and calcium compounds. compounds and the like.
Among these, at least one of a titanium compound and an antimony compound is preferred, and it is particularly preferred to use a polyester obtained using a titanium compound.
Therefore, the present polyester film preferably contains at least one of a titanium compound and an antimony compound, and more preferably contains a titanium compound.

By using the titanium compound, the amount of the antimony compound used can be reduced as a result, so the risk of forming new protrusions due to precipitation of the antimony compound on the film surface is reduced, and high surface smoothness can be achieved. can be maintained.
Therefore, as a particularly preferred embodiment, when the present polyester film has a multilayer structure, the polyester constituting at least one surface layer uses a titanium compound.

The content of titanium element derived from the titanium compound in the surface layer is preferably 3 ppm or more and 40 ppm or less, more preferably 4 ppm or more and 35 ppm or less, based on mass. Moreover, when the surface layer contains at least one of an antimony compound and a titanium compound, the antimony element content in the surface layer is preferably 0 ppm or more and 100 ppm or less. Within this range, it is possible to reduce the amount of foreign substances originating from the catalyst without lowering the production efficiency.
From the viewpoint of productivity and cost, it is also preferable not to use a titanium compound in the polyester constituting the layers other than the surface layer.
As described above, by including a titanium compound in the present polyester film, a polyester film having excellent smoothness can be obtained. If the laminated polyester film is provided with the present resin layer on such a basis, the laminated polyester film can be suitably used for sheet molding and the like.

<Intrinsic viscosity>
The intrinsic viscosity (IV) of the polyester constituting the present polyester film is preferably 0.50 dL/g or more, more preferably 0.55 dL/g or more, still more preferably 0.60 dL/g or more. Within this range, there is an advantage that the particles are highly dispersed due to an increase in shear stress during kneading. Moreover, the intrinsic viscosity (IV) of the polyester is, for example, 1.00 dL/g or less.
In addition, "the intrinsic viscosity (IV) of the polyester constituting the present polyester film" means the intrinsic viscosity (IV) of these mixed polyesters when using two or more polyesters having different intrinsic viscosities (IV). It shall be.

When the present polyester film has a multilayer structure, the intrinsic viscosity (IV) of the polyester constituting the surface layer is preferably within the above range.

<Particle>
Particles can also be incorporated into the present polyester film. By containing the particles, the polyester film is imparted with slipperiness and prevents the occurrence of scratches in each step, thereby improving handleability.
The type of particles to be contained in the present polyester film is not particularly limited as long as it is particles capable of imparting lubricity. Specific examples include silica, calcium carbonate, magnesium carbonate, barium carbonate, and calcium sulfate. , In addition to inorganic particles such as calcium phosphate, magnesium phosphate, kaolin, aluminum oxide, and titanium oxide, crosslinked polymers such as crosslinked silicone resin particles, crosslinked acrylic resin particles, crosslinked styrene-acrylic resin particles, and crosslinked polyester particles, calcium oxalate and organic particles such as ion exchange resins. Among these, organic particles, silica, aluminum oxide and the like are preferred. Among them, aluminum oxide is preferably contained from the viewpoint of hardening the layer to prevent damage to the film surface and maintaining smoothness.
Furthermore, precipitated particles obtained by precipitating and finely dispersing a part of a metal compound such as a catalyst during the polyester production process can also be used.

The shape of the particles to be used is not particularly limited either, and any of spherical, lumpy, rod-like, flattened and the like may be used.
Moreover, there are no particular restrictions on its hardness, specific gravity, color, and the like. Two or more types of these series of particles may be used in combination, if necessary.

The average particle size of the particles used is usually 5 μm or less, preferably 0.01 to 3 μm, more preferably 0.02 to 1 μm, still more preferably 0.03 to 0.5 μm. When the surface roughness of the film is 5 μm or less, the surface roughness of the film does not become too rough, and problems do not occur when the resin layer and various surface functional layers other than the resin layer are formed in a post-process. Moreover, if the average particle size is in the range, the haze can be kept low, and it is easy to ensure the transparency of the laminated polyester film as a whole.
The average particle size of the particles can be obtained by observing 10 or more particles with a scanning electron microscope (SEM) to measure the diameter of the particles, and calculating the average value. At that time, in the case of non-spherical particles, the average value of the longest diameter and the shortest diameter can be measured as the diameter of each particle.

When the present polyester film contains particles, it is preferable, for example, to provide a surface layer and an intermediate layer and to contain the particles in the surface layer. In addition, in the case of designing different front and back surfaces by a three-kind, three-layer structure or the like, particles may be contained in at least one of the surface layers.
Although the content of the particles depends on the average particle diameter, it is usually 5000 ppm or less, preferably 3000 ppm or less, more preferably 1000 ppm or less, based on the mass of the layer containing the particles. When the particles are not contained, or when the content of the particles is small, the slipperiness cannot be sufficiently imparted, and although the transparency of the polyester film is increased, the slipperiness may be insufficient. Therefore, it is necessary to take measures such as laminating the present resin layer to be described later to improve slipperiness. Moreover, if it is 5000 ppm or less, the transparency of a polyester film can be ensured sufficiently. In addition, the content of the particles in the resin-containing layer is not particularly limited, and is, for example, 50 ppm or more, preferably 100 ppm or more.

The resin layer to be described later may be provided on a layer containing particles of the polyester film, or may be provided on a layer substantially free of particles. In addition, the surface of the polyester film opposite to the surface on which the resin layer is provided (opposite surface) may be a layer containing substantially no particles or a layer containing particles. In the present invention, even if both the surface on which the resin layer is provided and the surface on the opposite side are layers that do not substantially contain particles, the resin layer having the concave-convex structure described later can improve the windability and the like. Further, by forming a layer containing particles on one or both of the surface on which the resin layer is provided and the surface on the opposite side, windability is further improved.
When imparting excellent smoothness to at least one surface of the present polyester film, the surface layer on the smooth side may contain particles or may contain substantially no particles, If a very smooth film is desired, it is preferably substantially free of particles.
The term "substantially does not contain" means that it does not contain intentionally, and specifically, the content of particles (particle concentration) is less than 50 ppm, more preferably 40 ppm or less, more preferably 40 ppm or less based on mass. means 30 ppm or less.
In this case, by laminating the present resin layer on the surface layer on the smooth surface side and/or on the surface layer on the opposite side of the smooth surface, the handling property when winding the film into a roll can be improved. Above all, from the viewpoint of improving the handleability while maintaining the smoothness of the film, it is preferable to make at least one side of the film smooth and to laminate the present resin layer on the opposite side.

The method for adding particles to the present polyester film is not particularly limited, and conventionally known methods can be employed. For example, in the case of a multi-layered polyester film, it can be added at any stage in the production of the polyester constituting each layer, but it is preferably added after the esterification or transesterification reaction is completed.

<Others>
In order to suppress the precipitation amount of the oligomer component, the film may be produced using a polyester having a low content of the oligomer component as a raw material. As a method for producing a polyester having a low content of oligomer components, various known methods can be used.
Further, the polyester film may have a structure of three or more layers, and the surface layer of the polyester film may be a layer using a polyester raw material with a low content of the oligomer component, thereby suppressing the precipitation amount of the oligomer component.
The polyester may also be obtained by subjecting the polyester to esterification or transesterification, followed by melt polycondensation under reduced pressure at a higher reaction temperature.

In addition to the particles described above, conventionally known ultraviolet absorbers, antioxidants, antistatic agents, heat stabilizers, lubricants, dyes, pigments, etc. can be added to the present polyester film as necessary. .

The thickness of the polyester film is not particularly limited as long as it can be formed as a film. More preferably 19 μm or more, particularly preferably 25 μm or more, and preferably 200 μm or less, more preferably 125 μm or less, still more preferably 80 μm or less, particularly preferably 50 μm or less.

<Method for producing polyester film>
Next, production examples of the present polyester film will be described in detail, but the invention is not limited to the following production examples. For example, when producing a biaxially stretched film, the dried pellets of the polyester raw material described above are extruded as a molten sheet from a die using a melt extruder such as an extruder, and cooled and solidified with a cooling roll such as a rotating cooling drum. A method of obtaining an unstretched sheet is preferred. In this case, it is preferable to increase the adhesion between the sheet and the cooling roll in order to improve the flatness of the sheet, and the electrostatic application adhesion method and/or the liquid application adhesion method are preferably employed.

The resulting unstretched sheet is then biaxially stretched. In that case, first, the unstretched sheet is stretched in one direction by a roll or tenter type stretching machine. The stretching temperature is usually 70 to 120° C., preferably 80 to 110° C., and the stretching ratio is usually 2.5 to 7.0 times, preferably 3.0 to 6.0 times.
Next, the film is stretched in a direction perpendicular to the stretching direction of the first stage. .0 times.
Subsequently, heat treatment is carried out at a temperature of usually 180 to 270° C. under tension or under relaxation of 30% or less to obtain a biaxially stretched film. This heat treatment is also called a heat setting process. The heat treatment may be performed in two or more steps with different temperatures.
Also, cooling may be performed in a cooling zone after the heat treatment. The cooling temperature is preferably higher than the glass transition temperature (Tg) of the polyester forming the film, and more specifically, preferably in the range of 100 to 160°C. This cooling may be performed in two or more steps with different temperatures.
In the above stretching, a method of stretching in one direction in two or more stages can also be employed. In that case, it is preferable to carry out so that the stretching ratios in the two directions finally fall within the above ranges.

A simultaneous biaxial stretching method can also be employed for the production of the present polyester film. In the simultaneous biaxial stretching method, the unstretched sheet is usually 70 to 120 ° C., preferably 80 to 110 ° C. while the temperature is controlled at the same time in the machine direction (longitudinal direction) and the width direction (horizontal direction). The draw ratio is preferably 4 to 50 times, more preferably 7 to 35 times, and still more preferably 10 to 25 times in terms of area ratio.
Subsequently, heat treatment is performed at a temperature of usually 170 to 250° C. under tension or under relaxation of 30% or less to obtain a stretched and oriented film. Conventionally known stretching methods such as a screw method, a pantograph method, and a linear drive method can be used for the simultaneous biaxial stretching apparatus that employs the above-described stretching methods.

<<resin layer>>
This laminated polyester film is provided with a resin layer formed from a resin composition on at least one side of the polyester film. The resin layer may be a cured resin layer.
As described above, the present resin layer is formed from a resin composition (hereinafter also referred to as "the present composition") and has an uneven structure.

<Uneven structure>
The concave-convex structure of the present resin layer has a fine shape. The shape of the concave-convex structure includes a concave-convex shape and/or a mesh shape.
The irregular shape is formed by fine protrusions formed by particles described later, thereby forming an uneven structure on the surface. The above-mentioned mesh shape intentionally makes the stretchability of the present composition inferior, and forms an uneven structure on the surface due to cracks in the coating film caused by making the film inferior in stretchability. The mesh shape and the uneven shape may be mixed on the surface of the resin layer.
The structure can be confirmed by means of various surface analysis techniques, such as an atomic force microscope (scanning probe microscope).

<Resin composition>
This composition contains the following compounds (A) and (B).
(A) one or more selected from the group consisting of a binder resin and a cross-linking agent; is 20% by mass or more.

Due to the composition described above, the composition has low stretching aptitude and tends to form a fine uneven structure due to cracking of the coating film, which will be described later. The total content of compounds (A) and (B) contained in the present composition is preferably 80% by mass or more as non-volatile components. More preferably 85% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass. If the said total content is the range which requires, it will become easy to obtain the fine uneven structure for which it desires. The upper limit of the total content is not particularly limited as long as it is 100% by mass or less.

(((Compound (A))))
The composition contains (A) one or more selected from a binder resin and a cross-linking agent.

((binder resin))
The binder resin selected as the above (A) is determined by gel permeation chromatography (GPC) measurement according to the "Polymer compound safety evaluation flow scheme" (November 1985, sponsored by the Chemical Substances Council). It is defined as a polymer compound having an average molecular weight (Mn) of 1,000 or more and having film-forming properties.
Such (A) binder resin is not particularly limited, and includes polyester resin, (meth)acrylic resin, polyurethane resin, polyvinyl resin (polyvinyl alcohol, vinyl chloride vinyl acetate copolymer, etc.), polyalkylene glycol, polyalkylene Conventionally known binder resins such as imine, methylcellulose, hydroxycellulose, and starches can be used. Among them, polyester resins, (meth)acrylic resins, and polyurethane resins are preferable from the viewpoint of film-forming properties and adhesion to polyester films. In this composition, (A) binder resin may be used individually by 1 type, and may use 2 or more types together.

By containing (A) the binder resin in the present composition, it becomes possible to form a film (resin layer) in which the (B) particles are held and fixed.

(polyester resin)
Examples of polyester resins include those composed of polyvalent carboxylic acids and polyvalent hydroxy compounds as shown below as main constituents.
That is, polyvalent carboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 4,4′-diphenyldicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6- Naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2-potassium sulfoterephthalic acid, 5-sodium sulfoisophthalic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, glutaric acid , succinic acid, trimellitic acid, trimesic acid, pyromellitic acid, trimellitic anhydride, phthalic anhydride, p-hydroxybenzoic acid, trimellitic acid monopotassium salts and ester-forming derivatives thereof can be used. Polyvalent hydroxy compounds include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 2-methyl-1,5-pentanediol, neo Pentyl glycol, 1,4-cyclohexanedimethanol, p-xylylene glycol, bisphenol A-ethylene glycol adduct, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polytetramethylene oxide glycol, dimethylol Propionic acid, glycerin, trimethylolpropane, sodium dimethylolethylsulfonate, potassium dimethylolpropionate, and the like can be used. One or more of these compounds may be appropriately selected, and a polyester resin may be synthesized by a conventional polycondensation reaction.

In addition, as a part of the polyvalent carboxylic acid, a product obtained by copolymerizing sulfoisophthalic acids such as 5-sodium sulfoisophthalic acid to introduce a sulfonic acid group into the polyester skeleton and neutralizing to make it hydrophilic is preferable. Used. The amount to be copolymerized is generally 1 to 13 mol %, preferably 3 to 10 mol %, more preferably 5 to 9 mol %, based on the total polycarboxylic acid. By introducing an appropriate amount of sulfonic acid groups, the hydrophilicity of the resin can be enhanced and the uneven structure can be easily formed. Furthermore, water dispersion stability can be improved.

((meth)acrylic resin)
A (meth)acrylic resin is a polymer composed of polymerizable monomers including acrylic and methacrylic monomers. These may be homopolymers, copolymers, or copolymers with polymerizable monomers other than acrylic and methacrylic monomers.
A (meth)acrylic polymer is a polymer having structural units derived from (meth)acrylic acid or (meth)acrylic acid alkyl esters. The (meth)acrylic polymer may be at least one polymer selected from (meth)acrylic acid and (meth)acrylic acid alkyl ester, or at least one selected from these and monomers other than these , such as styrene or styrene derivatives, monomers containing hydroxyl groups, and the like.
Copolymers of these polymers with other polymers (eg, polyester, polyurethane, etc.) are also included. Examples include block copolymers and graft copolymers. That is, the (meth)acrylic resin may be a (meth)acryl-modified polyester resin or a (meth)acryl-modified polyurethane resin.
Alternatively, a polymer obtained by polymerizing a polymerizable monomer in a polyester solution or a polyester dispersion (sometimes a mixture of polymers) is also included. Similarly, polymers obtained by polymerizing polymerizable monomers in polyurethane solutions and polyurethane dispersions (mixtures of polymers in some cases) are also included. Similarly, other polymer solutions or polymers obtained by polymerizing polymerizable monomers in dispersions (polymer mixtures in some cases) are also included, and these are also referred to herein as (meth)acrylic-modified polyester resins and , (meth)acrylic-modified polyurethane resin. The polyester and polyurethane used in the (meth)acrylic resin can be appropriately selected and used from those exemplified as the polyester and polyurethane used in the binder resin described later.
In addition, the (meth)acrylic resin may contain a hydroxy group and an amino group in order to further improve adhesion to the polyester film.

The polymerizable monomer is not particularly limited, but particularly representative compounds include various carboxyl group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, and citraconic acid. , and salts thereof; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, monobutyl hydroxy fumarate, monobutyl hydroxy itaconate, etc. Various hydroxyl group-containing Monomers; various alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, lauryl (meth)acrylate; (meth)acrylamide , diacetone acrylamide, or (meth)acrylonitrile; hydroxyl group-containing nitrogen-containing monomers such as N-methylol (meth)acrylamide; styrene, α-methylstyrene, divinylbenzene, vinyltoluene, etc. Various styrene derivatives; various vinyl esters such as vinyl propionate; various silicon-containing polymerizable monomers such as γ-methacryloxypropyltrimethoxysilane and vinyltrimethoxysilane; phosphorus-containing vinyl monomers; various vinyl halides such as vinylidene chloride; and various conjugated dienes such as butadiene.

Among the above (meth)acrylic resins, polymers obtained by polymerizing polymerizable monomers containing acrylic and methacrylic monomers are preferable, and more preferably the polymerizable monomers contain alkyl (meth)acrylic acid esters. preferable.
The present composition containing a (meth)acrylic resin is preferably diluted with a solvent to form a coating liquid as described later, and the solvent preferably contains water as the main solvent (50% by mass or more). That is, the polymerizable monomer preferably has a hydrophilic group such as a hydroxyl group or a carboxyl group from the viewpoint of facilitating dissolution or dispersion when the coating liquid is an aqueous system. Moreover, from the viewpoint of obtaining an uneven structure effectively, it is preferable to have a hydrophilic group such as a hydroxyl group or a carboxyl group.
Therefore, the acrylic resin is also preferably a polymer obtained by polymerizing an alkyl (meth)acrylate and a polymerizable monomer containing a hydrophilic group-containing monomer such as a hydroxyl group-containing monomer and a carboxyl group-containing monomer.
The acrylic resin may also be an emulsion polymer obtained by polymerizing a polymerizable monomer in the presence of a surfactant, for example.

(polyurethane resin)
A polyurethane resin is a polymer compound having a urethane bond in its molecule, and is preferably water-dispersible or water-soluble. In the present invention, it may be used alone or in combination of two or more.

In order to impart water dispersibility or water solubility, it is common and preferred to introduce a hydrophilic group such as a hydroxyl group, a carboxyl group, a sulfonic acid group, a sulfonyl group, a phosphoric acid group or an ether group into the polyurethane resin. Among the hydrophilic groups, a carboxyl group or a sulfonic acid group is particularly preferable from the viewpoint of adhesion between the resin layer and the polyester film. For example, introduction of carboxyl groups is preferably carried out using carboxyl group-containing polyhydric alcohols such as dimethylolpropionic acid and dimethylolbutanoic acid.

One of the methods for preparing polyurethane resins is by reacting a hydroxyl group-containing compound with isocyanate. As the hydroxyl group-containing compound used as a raw material, polyols are preferably used, and examples thereof include polyester polyols, polyether polyols, polycarbonate polyols, polyolefin polyols, and acrylic polyols. Among these, polyester polyols are preferable from the viewpoint of excellent adhesion to the polyester film. These compounds may be used alone or in combination.

Polyester polyols include those obtained from the reaction of polyhydric carboxylic acids or their anhydrides with polyhydric alcohols. Examples of polycarboxylic acids include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, fumaric acid, maleic acid, terephthalic acid, and isophthalic acid. Polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol , 2-methyl-2-propyl-1,3-propanediol, 1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2 ,5-dimethyl-2,5-hexanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-butyl-2 -hexyl-1,3-propanediol, cyclohexanediol, bishydroxymethylcyclohexane, dimethanolbenzene, bishydroxyethoxybenzene, alkyldialkanolamine, lactonediol and the like.

Polyether polyols include polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol and the like.

Polycarbonate-based polyols include polycarbonate diols obtained by a dealcoholization reaction from polyhydric alcohols and dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate, etc., such as poly(1,6-hexylene) carbonate, poly(3 -methyl-1,5-pentylene)carbonate and the like.
Among the above, polyester polyols are preferred.

Polyisocyanate compounds used to obtain polyurethane resins include aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, and tolidine diisocyanate; - Aliphatic diisocyanates having aromatic rings such as tetramethylxylylene diisocyanate; aliphatic diisocyanates such as methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate and hexamethylene diisocyanate; Alicyclic diisocyanates such as methane diisocyanate and isopropylidene dicyclohexyl diisocyanate are exemplified. These may be used alone or in combination of multiple types.

A chain extender may be used when synthesizing the polyurethane resin, and the chain extender is not particularly limited as long as it has two or more active groups that react with isocyanate groups. Alternatively, a chain extender having two amino groups can be mainly used.

Examples of chain extenders having two hydroxyl groups include aliphatic glycols such as ethylene glycol, propylene glycol and butanediol; aromatic glycols such as xylylene glycol and bishydroxyethoxybenzene; ester glycols such as neopentyl glycol hydroxypivalate. Glycols such as

Examples of chain extenders having two amino groups include aromatic diamines such as tolylenediamine, xylylenediamine and diphenylmethanediamine; ethylenediamine, propanediamine, hexanediamine, 2,2-dimethyl-1,3-propanediamine, 2-methyl-1,5-pentanediamine, trimethylhexanediamine, 2-butyl-2-ethyl-1,5-pentanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, etc. Alicyclic diamines such as 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, dicyclohexylmethanediamine, 1,4-diaminocyclohexane, 1,3-bisaminomethylcyclohexane, etc. mentioned.

(polyvinyl alcohol)
Polyvinyl alcohol is a compound having a polyvinyl alcohol moiety. For example, conventionally known polyvinyl alcohols including modified compounds obtained by partially acetalizing or butyralizing polyvinyl alcohol can be used. Although the degree of polymerization of polyvinyl alcohol is not particularly limited, it is usually 100 or more, preferably in the range of 300 to 40,000. When the degree of polymerization is 100 or more, it becomes easy to improve the water resistance of the resin layer. The degree of saponification of polyvinyl alcohol is not particularly limited, but is usually 70 mol% or more, preferably in the range of 70 to 99.9 mol%, more preferably 80 to 97 mol%, particularly preferably 86 to 99.9 mol%. A saponified polyvinyl acetate of 95 mol % is used in practice.

((crosslinking agent))
The cross-linking agent selected as the compound (A) is not particularly limited, and conventionally known cross-linking agents can be used. Examples include melamine compounds, oxazoline compounds, epoxy compounds, carbodiimide compounds, isocyanate compounds, silane coupling compounds and the like. Among them, it is preferable to contain a melamine compound from the viewpoint of increasing the strength of the coating film and from the viewpoint of improving the adhesion to the polyester film. Moreover, the resin layer can be easily formed into a cured resin layer by using a cross-linking agent.

(melamine compound)
A melamine compound is a compound having a melamine skeleton in the compound, and examples thereof include alkylolated melamine derivatives, compounds obtained by reacting alkylolated melamine derivatives with alcohol to partially or completely etherify them, and mixtures thereof. can be used.
Examples of alkylolation include methylolation, ethylolation, isopropylolation, n-butyrolation, and isobutyrolation. Among these, methylolation is preferable from the viewpoint of reactivity.
As the alcohol used for etherification, methanol, ethanol, isopropanol, n-butanol, isobutanol and the like are preferably used, and among these, methanol is more preferable.
Moreover, the melamine compound may be either a monomer or a polymer of dimers or higher, or a mixture thereof. Further, melamine may be partially co-condensed with urea or the like, and a catalyst may be further used in the present composition in order to increase the reactivity of the melamine compound.

(oxazoline compound)
An oxazoline compound is a compound having an oxazoline group in its molecule, and a polymer containing an oxazoline group is particularly preferred, and can be prepared by polymerization of an addition polymerizable oxazoline group-containing monomer alone or with another monomer. Addition polymerizable oxazoline group-containing monomers include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline and the like can be mentioned, and one or a mixture of two or more thereof can be used. Among these, 2-isopropenyl-2-oxazoline is suitable because it is easily available industrially. Other monomers are not limited as long as they are copolymerizable with addition-polymerizable oxazoline group-containing monomers. , n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group and cyclohexyl group); acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, Unsaturated carboxylic acids such as styrenesulfonic acid and salts thereof (sodium salts, potassium salts, ammonium salts, tertiary amine salts, etc.); Unsaturated nitriles such as acrylonitrile and methacrylonitrile; (meth)acrylamide, N-alkyl (Meth)acrylamide and N,N-dialkyl(meth)acrylamide (as alkyl groups, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; α-olefins such as ethylene and propylene; vinyl chloride and vinylidene chloride halogen-containing α,β-unsaturated monomers such as; α,β-unsaturated aromatic monomers such as styrene and α-methylstyrene; be able to.
Also, the oxazoline compound may have a polyalkylene oxide chain such as a polyethylene oxide chain, and for example, a (meth)acrylate having a polyalkylene oxide chain may be used as another monomer.

(epoxy compound)
Epoxy compounds are compounds having an epoxy group in the molecule, and include condensates with hydroxyl groups and amino groups such as epichlorohydrin, ethylene glycol, polyethylene glycol, glycerin, polyglycerin and bisphenol A, and polyepoxy compounds. , diepoxy compounds, monoepoxy compounds and glycidylamine compounds.
Examples of polyepoxy compounds include sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, triglycidyl tris(2-hydroxyethyl) isocyanate, glycerol polyglycidyl ether and trimethylolpropane poly glycidyl ether and the like.
Examples of diepoxy compounds include neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, resorcin diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, and polypropylene glycol diglycidyl ether. Ether and polytetramethylene glycol diglycidyl ether and the like.
Examples of monoepoxy compounds include allyl glycidyl ether, 2-ethylhexyl glycidyl ether and phenyl glycidyl ether, and examples of glycidylamine compounds include N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis (N,N-diglycidylamino)cyclohexane and the like. From the viewpoint of improving the adhesion of the resin layer to the polyester film, a polyether-based epoxy compound is preferred.
As for the amount of epoxy groups, a polyepoxy compound having a polyfunctionality of 3 or more is preferable to a bifunctional one.

(carbodiimide compound)
A carbodiimide compound is a compound having a carbodiimide structure, and is a compound having one or more carbodiimide structures in the molecule. More preferred are polycarbodiimide compounds having one or more carbodiimide structures.

A carbodiimide compound can be synthesized by a conventionally known technique, and generally a condensation reaction of a diisocyanate compound is used. The diisocyanate compound is not particularly limited, and both aromatic and aliphatic compounds can be used. Specifically, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, phenylene diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, dicyclohexyl diisocyanate and dicyclohexylmethane 4,4'-diisocyanate.
Furthermore, in order to improve the water solubility and water dispersibility of the polycarbodiimide compound, a surfactant may be added, polyalkylene oxide, quaternary ammonium salt of dialkylamino alcohol, and Hydrophilic monomers such as hydroxyalkylsulfonates may be added and used.

(isocyanate compound)
An isocyanate compound is a compound having an isocyanate derivative structure represented by isocyanate or blocked isocyanate. Examples of isocyanates include aromatic isocyanates such as tolylene diisocyanate, xylylene diisocyanate, methylene diphenyl diisocyanate, phenylene diisocyanate and naphthalene diisocyanate; aliphatic isocyanates such as methylene diisocyanate, propylene diisocyanate, lysine diisocyanate, trimethylhexamethylene diisocyanate and hexamethylene diisocyanate; Alicyclic isocyanate etc. are illustrated.
Polymers and derivatives of these isocyanates such as buret products, isocyanurate products, uretdione products and carbodiimide modified products are also included. These may be used alone or in combination of multiple types. Among the above isocyanates, aliphatic isocyanates or alicyclic isocyanates are more preferable than aromatic isocyanates in order to avoid yellowing due to ultraviolet rays.

When used in the form of blocked isocyanate, blocking agents include, for example, bisulfites; phenolic compounds such as phenol, cresol and ethylphenol; alcoholic compounds such as propylene glycol monomethyl ether, ethylene glycol, benzyl alcohol, methanol and ethanol. Compounds; active methylene compounds such as methyl isobutanoylacetate, dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate and acetylacetone; mercaptan compounds such as butyl mercaptan and dodecyl mercaptan; ε-caprolactam, δ-valerolactam and the like amine compounds such as diphenylaniline, aniline and ethyleneimine; acid amide compounds of acetanilide and acetic acid amide; These may be used alone or in combination of two or more.

(Silane coupling compound)
A silane coupling compound is an organosilicon compound having an organic functional group and a hydrolyzable group such as an alkoxy group in one molecule. For example 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxy Epoxy group-containing compounds such as cyclohexyl)ethyltrimethoxysilane; Vinyl group-containing compounds such as vinyltrimethoxysilane and vinyltriethoxysilane; Styryl group-containing compounds such as p-styryltrimethoxysilane and p-styryltriethoxysilane; - (meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, etc. ( meth) acrylic group-containing compounds; 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3 -aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane, 3-triethoxysilyl-N- Amino group-containing compounds such as (1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane; tris(trimethoxysilylpropyl)isocyanate Nurate, isocyanurate group-containing compounds such as tris(triethoxysilylpropyl) isocyanurate; 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxy A mercapto group-containing compound such as silane can be used.

The content of compound (A) in the present composition is preferably 10 to 80% by mass, more preferably 25 to 70% by mass, more preferably 40 to 60% by mass, as a proportion of the total nonvolatile components in the present composition. It is in the range of % by mass. By setting the content to 10% by mass or more, a film having film-forming properties and containing particles can be obtained. In addition, by having adhesion to the polyester film, it is possible to suppress the falling off of the coating film. In addition, by setting the content to 80% by mass or less, the content of particles becomes high, and it becomes possible to form irregularities in the coating film by increasing the hardness of the coating film.

Although the compound (A) contains one or more selected from a binder resin and a cross-linking agent, it preferably contains a binder resin from the viewpoint of obtaining better film-forming properties. Furthermore, it is more preferable to contain a binder resin and a cross-linking agent from the viewpoint of further improving the coating film strength and adhesion to the polyester film.

((Compound (B)))
The composition contains (B) particles. When the present composition contains the (B) particles, the stretching aptitude of the coating film is lowered, and an uneven structure is likely to be formed. In addition, by increasing the hardness of the formed concave-convex structure, it is possible to effectively improve the air release property.

Examples of the particles (B) include inorganic particles such as silica, calcium carbonate, magnesium carbonate, barium carbonate, calcium sulfate, calcium phosphate, magnesium phosphate, kaolin, zirconium oxide, aluminum oxide and titanium oxide, and crosslinked silicone resin particles. , crosslinked acrylic resin particles, crosslinked styrene-acrylic resin particles, crosslinked polymers such as crosslinked polyester particles, and organic particles such as calcium oxalate and ion exchange resins. Among these, zirconium oxide, titanium oxide and silica are preferred. The particles (B) may be used singly or in combination of two or more.

The shape of the particles (B) to be used includes spherical, massive, rod-like, flattened, chain-like and the like. Among these, a spherical shape is preferable from the viewpoint of facilitating uniform distribution in the compound (A).

The average particle diameter of the particles (B) is preferably 1 to 100 nm, more preferably 4 to 60 nm, still more preferably 8 to 40 nm. When the average particle diameter is within such a range, it is possible to suppress the generation of coarse projections due to particle aggregation and contamination of the process due to falling off of particles, making it easier to obtain a desired fine uneven structure.
The method of measuring the average particle diameter of the fine particles is a method of calculating from the specific surface area and the density of the particles measured by a specific surface area measuring device, or by observing with a transmission electron microscope (TEM) or a scanning electron microscope (SEM). There are a method of calculating the diameter of particles and a method of determining the diameter from measurement by a dynamic light scattering method.

The content of compound (B) in the present composition is 20% by mass or more as a proportion of all non-volatile components in the present composition. The content is preferably 90 mass % or less, more preferably 30 to 75 mass %, still more preferably 40 to 60 mass %. By setting the content to 20% by mass or more, it becomes possible to easily form the concave-convex structure, and to increase the hardness of the formed concave-convex structure to effectively improve the air release property. Further, by setting the content to 90% by mass or less, it is possible to include necessary amounts of other components, and it is possible to form an uneven film and obtain adhesion to a polyester film. Also, by setting the content of the compound (B) to a certain value or less, it becomes easier to prevent the coating film from coming off.

((Other ingredients))
In addition to the components described above, a cross-linking catalyst, an antifoaming agent, a coatability improver, a surfactant, a thickener, an organic lubricant, an ultraviolet absorber, and an antioxidant are used within the scope of the present invention. , foaming agents, dyes, pigments, and other additives may be added as appropriate.

((solvent))
The composition may be diluted with a solvent to form a coating liquid. That is, the present composition may be applied, for example, to the present polyester film as a liquid coating liquid, dried and cured as necessary to form a resin layer.
Each component (compounds (A) and (B), other components, etc.) constituting the present composition may be dissolved in a solvent or dispersed in a solvent.
When used as a coating liquid, the concentration of all non-volatile components in the present composition in the coating liquid is preferably 0.1 to 50% by mass. If it is 0.1% by mass or more, a resin layer having a desired thickness can be efficiently formed. On the other hand, if it is 50% by mass or less, the appearance of the resin layer can be improved by suppressing the viscosity during coating, and the stability in the coating liquid can be enhanced.

The solvent is not particularly limited, and both water and organic solvents can be used. From the viewpoint of environmental protection, it is preferable to use water as the main solvent (50% by mass or more of the total solvent) to form an aqueous coating solution. The water content is preferably 60% by mass or more, more preferably 70% by mass or more. The aqueous coating liquid may contain a small amount of organic solvent. A specific amount of the organic solvent is preferably equal to or less than the amount of water on a mass basis, for example, 50% by mass or less, preferably 40% by mass or less, more preferably 30% by mass or less in the solvent.
Organic solvents used in combination with water include alcohols such as ethanol, isopropanol, ethylene glycol and glycerin; ethers such as ethyl cellosolve, t-butyl cellosolve, propylene glycol monomethyl ether and tetrahydrofuran; ketones such as acetone and methyl ethyl ketone; ethyl acetate. and amines such as dimethylethanolamine. These can be used singly or in combination. By appropriately selecting and including these organic solvents in the aqueous coating liquid as necessary, the stability and coatability of the coating liquid can be improved in some cases.

When only an organic solvent is used as the solvent, the organic solvent includes aromatic hydrocarbons such as toluene; aliphatic hydrocarbons such as hexane, heptane and isooctane; esters such as ethyl acetate and butyl acetate. ketones such as ethyl methyl ketone and isobutyl methyl ketone; alcohols such as ethanol and 2-propanol; ethers such as diisopropyl ether and dibutyl ether. These may be used singly or in combination of two or more in consideration of solubility, coatability, boiling point, and the like.

In the resin layer, it is assumed that unreacted substances of each component (compounds (A) and (B), other components, etc.) constituting the present composition, compounds after reaction, or mixtures thereof are present. can.
Incidentally, the analysis of each component in the resin layer can be performed by, for example, TOF-SIMS, ESCA, fluorescent X-rays, and the like.

<Method for Forming Resin Layer>
Next, a method for forming the resin layer that constitutes the present laminated polyester film will be described.
The present resin layer may be formed by applying the present composition to a polyester film and, if necessary, performing treatments such as drying, curing, heat treatment, etc. on the applied present composition, and at least heat treatment. is preferred. The method of applying the resin composition is not particularly limited, and conventionally known coating methods such as reverse gravure coating, direct gravure coating, roll coating, die coating, bar coating and curtain coating can be used.

Moreover, as a method of forming the resin layer, there are in-line coating and off-line coating. The method of heat-treating the applied resin composition is not particularly limited. It is preferable to perform the heat treatment for 40 seconds as a guideline. On the other hand, when the resin layer is provided by in-line coating, it is generally preferable to perform heat treatment at 70 to 280° C. for 3 to 200 seconds.
Moreover, the heat treatment may be performed in two or more stages with different temperatures within the above temperature range. At least part of the heat treatment may be performed by heating during stretching. Drying and curing are preferably performed together by heating in the heat treatment.

In the present invention, the resin layer is preferably formed by in-line coating, which treats the film surface during the process of forming the polyester film.
In-line coating is a method of coating within the polyester film manufacturing process. Specifically, it is a method of coating at any stage from melt extrusion of polyester to stretching, heat setting and winding. . Usually, it is coated on an unstretched sheet obtained by melting and quenching, a stretched uniaxially stretched film, a biaxially stretched film before heat setting, or a film after heat setting and before winding up.

Although not limited to the following, for example, in sequential biaxial stretching, a method of coating a uniaxially stretched film stretched in the longitudinal direction (machine direction) and then stretching in the transverse direction is excellent. According to such a method, since film formation and resin layer formation can be performed simultaneously, there is an advantage in terms of manufacturing cost, and since stretching is performed after coating, the thickness of the resin layer can be changed by the stretching ratio. It is possible to perform thin film coating more easily compared to off-line coating films.

Further, by providing the resin layer on the film before stretching, the resin layer can be stretched together with the polyester film, thereby firmly adhering the resin layer to the polyester film.

Furthermore, in the production of biaxially stretched polyester film, the film can be restrained in the vertical and horizontal directions by stretching while holding the ends of the film with a clip or the like. High temperature can be applied while maintaining flatness without entering etc.
Therefore, since the heat treatment applied after coating can be performed at a high temperature that cannot be achieved by other methods, the film-forming property of the resin layer is improved, and the resin layer and the polyester film can be adhered more firmly. Furthermore, a strong resin layer can be formed, and performances such as resistance to migration to various functional layers that can be formed on the resin layer and resistance to moist heat can be improved.

In particular, in the present invention, such a method is most suitable as a manufacturing method for forming cracks in the coating film. The content of each of the compounds (A) and (B) in the present composition is adjusted to make the stretchability of the present composition inferior. In addition, by adopting a production method in which the present composition is coated and then stretched, it is possible to form an uneven structure on the surface of the resin layer due to cracks in the coating film caused by stretching a film with poor stretchability. . Those skilled in the art have conventionally considered coating film cracking to be one form of coating defects, and have sought to form a uniform coating film that minimizes the occurrence of coating film cracking. One of the causes of coating film cracking is insufficient stretchability of the resin composition, so the resin composition is designed to have sufficient stretchability. However, the present inventors have come to utilize such cracks in the coating film as one of means for forming a fine uneven structure on the surface of the resin layer.

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

The coating amount of the nonvolatile component of the resin layer is preferably 0.005 to 0.95 g/m ² , more preferably 0.02 to 0.5 g/m ² , still more preferably 0.04 to 0.3 g/m 2 . ² , particularly preferably 0.06 to 0.2 g/m ² . If the coating amount is within such a range, a fine uneven structure can be formed due to coating film cracks and the like.
The coating amount can be obtained by calculation from the non-volatile component concentration of the coating liquid, the coating amount before drying derived from the consumption of the coating liquid, the transverse stretching ratio, and the like. Moreover, the coating amount of the non-volatile component is the coating amount in the present laminated polyester film, for example, when drying and stretching are performed, it is the coating amount after drying and stretching.

<<<Physical properties of laminated polyester film>>>
Kurtosis (Sku) of the surface of the resin layer of the laminated polyester film is less than 3.0.
Kurtosis (Sku) is a parameter related to the tip shape of unevenness. Sku=3 is a normal distribution, and if Sku>3, the height distribution is sharp, that is, the shape has many sharp unevenness on the surface. If it is 3, it can be evaluated that the height distribution of the surface unevenness is collapsed, that is, the surface is relatively flat.
Therefore, if the kurtosis (Sku) is less than 3.0, since the projections have a flat surface, the projection apexes are less likely to be crushed when the films are stacked, and the air release property can be efficiently maintained. can. From such a viewpoint, the kurtosis is preferably 2.9 or less, more preferably 2.8 or less, still more preferably 2.6 or less, particularly preferably 2.4 or less, and particularly preferably 2.2 or less. be. The lower limit is not particularly limited and is 0.1.

Kurtosis (Sku) is one of the surface roughness parameters (ISO 25178), can evaluate the sharpness (kurtosis) of a histogram of height distribution, and is obtained from the following equation (1).
When the surface is the XY plane and the height direction is the Z axis, A: the defined area (the entire image), Z (x, y): the height of the image point (x, y) from the plane of 0 Height, Sq: root mean square height (equivalent to standard deviation of height distribution), is expressed as follows.

The arithmetic mean roughness (Ra) of the resin layer surface of the laminated polyester film is preferably 10 nm or more, more preferably 20 nm or more, still more preferably 50 nm or more, and particularly preferably 80 nm or more. Although the upper limit is not particularly limited, it is preferably 600 nm, more preferably 400 nm, and still more preferably 200 nm. When the arithmetic mean roughness (Ra) is 10 nm or more, it can be said that the present resin layer has a fine uneven structure, and the handleability of the present laminated polyester film is improved. Further, when the arithmetic mean roughness (Ra) is 600 nm or less, the concave-convex structure of the present resin layer can be said to have a sufficiently fine shape.

Arithmetic average roughness (Ra) is one of the line roughness parameters (JIS B 0601) and represents the average value of the average height difference from the average surface.
That is, when a portion of the reference length L is extracted, and the average line of this extracted portion is the x-axis and the direction of the longitudinal magnification is the y-axis, the roughness curve is represented by y = Z (x), the following equation (2) requested from.

The ten-point average roughness (Rzjis) of the surface of the resin layer is preferably 60 nm or more, more preferably 150 nm or more, and still more preferably 250 nm or more. Although the upper limit is not particularly limited, it is preferably 800 nm, more preferably 600 nm, and still more preferably 450 nm. When the ten-point average roughness (Rzjis) is 60 nm or more, it can be said that the present resin layer has a sufficient uneven structure. Further, when the ten-point average roughness (Rzjis) is 800 nm or less, it can be said that the concave-convex structure of the present resin layer has a sufficiently fine shape.

The ten-point average roughness (Rzjis) is one of the line roughness parameters (JIS B 0601), and in the reference length L, the average from the maximum peak height (Zp) of the contour curve to the fifth, It represents the sum of the average of the deepest valley depths (Zv) to the fifth, and is obtained from the following equation (3).

The load length ratio (Rmr(70)) of the roughness curve at a cutting level of 70% of the resin layer surface is preferably 82% or less, more preferably 65% or less, and still more preferably 60% or less. The lower limit is not particularly limited, and is about 1%, preferably 10% or more, more preferably 15% or more.

Here, the inventor considered that the load length ratio (Rmr(70)) is effective as an index representing the uneven distribution of the uneven structure. For example, when the concave distribution is large, the numerical value of the load length ratio (Rmr(70)) is small, and when the convex distribution is large, the numerical value of the load length ratio (Rmr(70)) is large.
If the load length ratio (Rmr(70)) is 82% or less, an appropriate fine uneven structure is formed, and when the film is wound into a roll, the gap between the films becomes large, and air It is possible to improve the easiness of coming off, and improve winding characteristics and the like.

The load length ratio (Rmr (c)) is one of the line roughness parameters (JIS B 0601), and is the load length ML (c) of the contour element at the cutting level c (height % or μm). It represents the ratio to the evaluation length Ln and is obtained from the following equation (4).

The root-mean-square gradient (Sdq) of the resin layer surface of the laminated polyester film is preferably 0.1 or more, more preferably 0.25 or more, and still more preferably 0.45 or more. On the other hand, the root-mean-square gradient (Sdq) is preferably 3 or less, more preferably 1.0 or less. When the root-mean-square gradient (Sdq) is 0.1 or more, the difference between peaks and valleys of the uneven structure is clear, and air release can be enhanced. Further, when the root mean square gradient (Sdq) is 3 or less, coarse projections can be suppressed.

The root-mean-square gradient (Sdq) is one of the surface roughness parameters (ISO 25178) and is obtained from the following formula (5).
The root-mean-square gradient (Sdq) represents the average magnitude of the local gradient (inclination) of the uneven shape of the surface, and the larger the value, the steeper the surface.

The developed interface area ratio (Sdr) of the resin layer surface is preferably 0.5% or more, more preferably 3% or more, and still more preferably 9% or more. On the other hand, the developed interface area ratio (Sdr) is preferably 60% or less, more preferably 50% or less. If the developed interface area ratio (Sdr) is 0.5% or more, the winding characteristics can be improved by forming a fine uneven structure. Further, when the developed interface area ratio (Sdr) is 60% or less, undulations are moderately suppressed, and coarse projections can be prevented.

The developed interface area ratio (Sdr) is one of the surface roughness parameters (ISO 25178) and is obtained from the following formula (6).
The developed interface area ratio (Sdr) represents how much the developed area (surface area) of the defined region increases with respect to the area of the defined region, that is, the increase rate of the surface area. value increases.

The kurtosis (Sku), arithmetic mean roughness (Ra), ten-point mean roughness (Rzjis), load length ratio (Rmr (70)), root mean square gradient (Sdq) and developed interface area ratio (Sdr) are , the composition and content in the present composition, the method of forming the resin layer and various conditions in the forming process.

In addition, kurtosis (Sku), arithmetic mean roughness (Ra), ten point mean roughness (Rzjis), load length ratio (Rmr (70)), root mean square gradient (Sdq) and developed interface area of resin layer surface The modulus (Sdr) is measured by the method described in Examples using an atomic force microscope (scanning probe microscope). Measurement by an atomic force microscope (scanning probe microscope) can capture a finer structure of the surface, and it is possible to obtain numerical values that strongly reflect the effect of the resin layer.

The surface arithmetic average roughness (Sa) of the resin layer surface of the laminated polyester film is preferably in the range of 1 to 70 nm, more preferably in the range of 2 to 50 nm, and still more preferably in the range of 3 to 30 nm. If the arithmetic mean roughness (Sa) is in the range, extremely large unevenness can be reduced while having fine unevenness. Therefore, for example, it is possible to ensure the handleability of the present laminated polyester film, suppress wrinkles when winding it into a roll, and use it as a support for a ceramic green sheet in the manufacturing process of a laminated ceramic capacitor. When a mold release layer or a ceramic layer is provided on the film surface opposite to the provided surface, it is possible to prevent projection transfer to the ceramic layer due to projections on the surface of the resin layer and breakage of the ceramic layer.

Average surface roughness (Sa) is one of the surface roughness parameters (ISO 25178), and is a three-dimensional expansion of two-dimensional Ra (arithmetic mean roughness of lines). It is obtained by dividing the volume of the portion surrounded by the surface by the measurement area, and is obtained from the following formula (7).
When the surface is the XY plane and the height direction is the Z axis, A: the defined area (the entire image), Z (x, y): the height of the image point (x, y) from the plane of 0 The height is expressed as follows.

Also, the maximum peak height (Sp) of the resin layer surface is preferably 800 nm or less, more preferably 300 nm or less, and even more preferably 200 nm or less. On the other hand, the maximum peak height (Sp) is preferably 10 nm or more, more preferably 20 nm or more. If the maximum peak height (Sp) is 800 nm or less, protrusions can be reduced. Therefore, for example, when the present laminated polyester film is used as a support for a ceramic green sheet in the manufacturing process of a laminated ceramic capacitor, and a release layer or a ceramic layer is provided on the film surface opposite to the surface provided with the present resin layer. Therefore, it is possible to prevent projection transfer to the ceramic layer and destruction of the ceramic layer due to projections on the surface of the present resin layer. In addition, when the maximum peak height (Sp) is 10 nm or more, it is possible to ensure the handleability of the present laminated polyester film, and it is possible to suppress wrinkles when wound into a roll.

The maximum peak height (Sp) is one of the surface roughness parameters (ISO 25178), represents the maximum height from the average surface of the surface, and is represented by the following formula (8).

On the other hand, the surface arithmetic mean roughness (Sa) of the surface opposite to the resin layer surface of the laminated polyester film is preferably 15 nm or less, more preferably 9 nm or less, and still more preferably 5 nm or less. On the other hand, the arithmetic mean roughness (Sa) is preferably 0.3 nm or more from the viewpoint of film handleability.

Also, the surface maximum peak height (Sp) on the surface opposite to the resin layer surface is preferably 800 nm or less, more preferably 500 nm or less, and still more preferably 100 nm or less. On the other hand, although the lower limit of the maximum peak height (Sp) is not particularly limited, it is preferably 5 nm or more, more preferably 10 nm or more, and still more preferably 20 nm or more from the viewpoint of film handleability.

When using this laminated polyester film as a release film for molding the green sheets of laminated ceramic capacitors, as a base material for releasing interlayer insulating resin, as a base material for dry film resist, etc., processing using the smoothness of the film is required. done. In that case, at least one side of the laminated polyester film is preferably smooth, and the surface opposite to the surface on which the resin layer is formed. In this case, the transfer of irregularities and protrusions on the film surface is small, and good processing is possible. In particular, when the present laminated polyester film is used as a support for a ceramic green sheet in the manufacturing process of a laminated ceramic capacitor, and a release layer or a ceramic layer is provided on the film surface opposite to the surface provided with the present resin layer, If the arithmetic mean roughness (Sa) and the maximum peak height (Sp) are within the above ranges, it will be an extremely smooth film, and it is also useful for thinning ceramic green sheets when miniaturizing and increasing the capacity of laminated ceramic capacitors. Correspondence becomes possible.

The arithmetic mean roughness (Sa) and maximum peak height (Sp) of the surface of the resin layer can be adjusted by the composition and content in the present composition.
In addition, the arithmetic mean roughness (Sa) and the maximum peak height (Sp) of the surface opposite to the resin layer surface can be adjusted by the type, average particle size and content of the particles contained in the surface layer of the present polyester film. can.

The arithmetic average roughness (Sa) and the maximum peak height (Sp) of the resin layer surface and the surface opposite to the resin layer surface can be measured by a non-contact surface roughness meter using light interference, and specific can be measured by the method described in Examples. If measured by this method, a numerical value reflecting a wider area of the present laminated polyester film can be obtained.

The coating film retention rate of the present resin layer is preferably 60% or more, more preferably 70% or more, and still more preferably 90% or more. The upper limit of the coating film retention rate is not particularly limited, and is 100% or less. If the coating film retention is within such a range, it is possible to suppress contamination in the process due to the dropped coating film.
In addition, the said coating-film retention rate can be measured by the method as described in an Example.

The coefficient of static friction between the resin layer surface and the opposite surface of the laminated polyester film is preferably 1.0 or less, more preferably 0.7 or less, and still more preferably 0.6 or less.
When the present laminated polyester film is wound into a roll, the friction coefficient between the resin layer surface and the opposite surface is important because the resin layer surface and the opposite surface are in contact with each other.
Therefore, if the coefficient of static friction is in the range, the rugged structure of the present resin layer improves the slipperiness and the handleability of the present laminated polyester film.
The static friction coefficient can be measured by the method described in Examples.

An air leakage index can be used as an index for evaluating handling properties such as windability of the present laminated polyester film. If the air leakage index is low, air trapped in the laminated polyester film when it is rolled up can be easily released, and defects in the appearance of the roll such as wrinkles and uneven edges can be prevented. In addition, when the air leakage index is high, the trapped air escapes after a sufficient period of time, especially during transportation, causing problems such as displacement of the film in the winding core direction and scratches due to displacement.

The air leakage index may be, for example, 130,000 seconds or less. If it is 130,000 seconds or less, it can be said that it has a certain handleability.
In addition, the surface opposite to the surface on which the resin layer is formed, that is, when used as a release film for molding green sheets of laminated ceramic capacitors, a base material for releasing interlayer insulating resin, a base material for dry film resist, etc. Further, as described above, the smooth surface of the film used for processing preferably has an arithmetic mean roughness (Sa) of 9 nm or less, or a maximum peak height (Sp) of 500 nm or less. In this case, the air leakage index is preferably 130,000 seconds or less, more preferably 50,000 seconds or less, and even more preferably 30,000 seconds or less. In this way, when the smooth surface of the film is extremely smooth, more precise processing can be performed by utilizing the smoothness of the film, and the uneven structure of the resin layer improves the air leakage index within the above range. As a result, the windability is improved, and the handleability of the present laminated polyester film is improved.
The air leakage index can be measured by the method described in Examples.

<<<Uses of laminated polyester film>>>
The present resin layer is characterized in that it is composed of a resin composition containing a certain amount of a specific compound and has a specific roughness structure, so that it can develop a fine uneven structure. In addition, it is also characterized by focusing on the degree of sharpness (kurtosis), which can evaluate the tip shape of unevenness as an index representing the roughness structure.
Such a design concept has made it possible to precisely control a fine uneven structure, which is difficult to achieve with the conventional particle kneading type film manufacturing method. In addition, by having a specific roughness structure, it is possible to improve the easiness of air evacuation even if it is a thin film, making it possible to provide a laminated polyester film with excellent handleability.

The laminated polyester film can be used for various purposes for the purpose of improving handling properties, and the uses are not particularly limited.
Among them, as described above, since it has a fine uneven structure, if it is used for sheet molding, it exhibits good winding properties even when winding a highly smooth film into a roll, and wrinkles are less likely to occur. It can be suitably used as a polyester film for sheet molding. As a polyester film for sheet molding, for example, for multi-layer ceramic capacitor (MLCC) green sheet molding, interlayer insulation resin, dry film resist (DFR), multilayer circuit board, etc. process applications. This laminated polyester film is used, for example, as a support in mold release and process applications.
The sheet-forming polyester film may be used, for example, in a step of forming various sheets such as a green sheet by coating or laminating various materials on at least one side of the film. When the resin layer is provided only on one side, various materials are preferably applied or laminated on the film side opposite to the side provided with the resin layer. It may be coated or laminated on the face side. In the polyester film for sheet molding, a release layer or the like may be appropriately provided on the film surface opposite to the surface provided with the resin layer.

Among them, this laminated polyester film can form a uniform thin dielectric layer when used as a support for a ceramic green sheet in the manufacturing process of MLCC, and the switching frequency of polyester film rolls due to lengthening can be reduced. can contribute to the improvement of productivity due to the reduction of In particular, it can be suitably used as a support for semi-green sheets used in MLCCs for automobiles.

<<<explanation of words>>>
In the present invention, the term "film" includes the "sheet", and the term "sheet" includes the "film".
In the present invention, when described as "X to Y" (X and Y are arbitrary numbers), unless otherwise specified, "X or more and Y or less" and "preferably larger than X" or "preferably Y It also includes the meaning of "less than".
In addition, when described as "X or more" (X is an arbitrary number), it includes the meaning of "preferably greater than X" unless otherwise specified, and is described as "Y or less" (Y is an arbitrary number). If not otherwise specified, it also includes the meaning of "preferably smaller than Y".

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

<Evaluation method>
Intrinsic viscosity of polyester (IV)
Precisely weigh 1 g of polyester from which components incompatible with polyester have been removed, add 100 mL of a mixed solvent of phenol/tetrachloroethane = 50/50 (mass ratio) to dissolve it, and measure the viscosity using a viscosity measuring device "VMS-022UPC F10" ( (manufactured by Rigosha Co., Ltd.), and measured at 30°C.

Average particle diameter of particles contained in the polyester film The average particle diameter of the particles is obtained by observing 10 or more particles with a scanning electron microscope (SEM) to measure the diameter of the particles, and calculating the average value as the average particle diameter ( average primary particle diameter). At that time, in the case of non-spherical particles, the average value of the longest diameter and the shortest diameter was measured as the diameter of each particle.

(3) Concavo-convex structure of resin layer Measurement was performed under the following conditions using a scanning probe microscope (SPM-9700 manufactured by Shimadzu Corporation).
Probe: Silicon cantilever Scanning mode: Dynamic mode Scanning range: 25 μm × 25 μm
Scanning speed: 0.8Hz
Number of pixels: 512 × 512 data points Observe the cross-sectional shape of 25 μm width from the obtained data. When no protrusions or recesses could be confirmed, it was determined that the uneven structure was "absent".

(4) Arithmetic mean roughness (Ra) and ten-point mean roughness (Rzjis) of resin layer surface
From the data of the scanning probe microscope measured by the above method (3), a cross-sectional analysis of a width of 25 μm is performed in parallel with the tenter stretching direction (i.e., the lateral direction), and the arithmetic average roughness (Ra) and ten-point average roughness (Rzjis) was determined. Cross-sectional analysis data were obtained at 10 points at equal intervals in the film-forming direction (that is, the longitudinal direction) of the film, and these were averaged.

(5) Load length ratio of resin layer surface (Rmr(70))
Cross-sectional analysis with a scanning probe microscope was performed in the same manner as in (4) above, and the load length ratio (Rmr(70)) at a cutting level of 70% was determined. Cross-sectional analysis data were obtained at 10 points at equal intervals in the film-forming direction (that is, the longitudinal direction) of the film, and these were averaged.

(6) Curtosis (Sku), root-mean-square gradient (Sdq) and developed interfacial area ratio (Sdr) of resin layer surface
The image data obtained from the scanning probe microscope data measured by the method (3) above was analyzed using the image analysis software SPIP6.2.5 ImageMetrology, and the kurtosis (Sku), the root mean square gradient (Sdq) and A developed interface area ratio (Sdr) was calculated.

(7) Arithmetic mean roughness (Sa) and maximum peak height (Sp) of the surface of the resin layer and the surface opposite to the resin layer
The film surface is measured using a non-contact surface/layer cross-sectional shape measurement system VertScan (registered trademark) R550GML manufactured by Ryoka Systems Co., Ltd., CCD camera: SONY HR-50 1/3 ', objective lens: 20x, mirror Cylinder: 1X Body, Zoom lens: No Relay, Wavelength filter: 530 white, Measurement mode: Wave, measure an area of 640 μm × 480 μm, use the output by 4th order polynomial correction, arithmetic mean roughness (Sa) And the maximum peak height (Sp) was obtained by averaging 10 points.

(8) Retention rate of coating film Bemcot (“M-3II” manufactured by Asahi Kasei Fibers Co., Ltd.) is attached to a rubbing tester (manufactured by Ohira Rika Kogyo Co., Ltd.), and the resin layer surface of the sample film is reciprocated 5 times with an arm load of 680 g. Ta. The surface of the resin layer before and after the treatment was measured by X-ray fluorescence spectroscopy (XRF) to measure the amount of components derived from the resin layer. The retention rate of the coating film was calculated by the following formula.
Coating film retention (%) = Amount of resin layer components after treatment / Amount of resin layer components before treatment x 100

(9) Static Friction Coefficient The static friction coefficient between the resin layer surface and the opposite side of the laminated polyester film was obtained by the following method.
The film was attached to a smooth glass plate having a width of 10 mm and a length of 100 mm so that the surface opposite to the surface provided with the resin layer was the upper surface. A film cut into a width of 18 mm and a length of 120 mm is placed on the film so that the surface provided with the resin layer is the bottom surface, and a metal pin having a diameter of 8 mm is pressed on the film, and the metal pin is placed on the glass plate. The frictional force was measured by sliding in the longitudinal direction at a load of 30 g and 40 mm/min, and the maximum value immediately after sliding was evaluated as the coefficient of static friction. The measurement was carried out at room temperature of 23±1° C. and humidity of 50±0.5% RH. The number of measurements (N) was 10, and the average value was adopted.
Static friction coefficient (μs) = Fs/weight load (in the above formula, the unit of Fs and Fd is g weight, and the unit of weight load is g weight)

(10) Air Leakage Index Using a digibec smoothness tester (manufactured by Toyo Seiki Co., Ltd., "DB-2"), measurements were made in accordance with JIS P8119 at a temperature of 23°C and a humidity of 50% RH. The pressure of the pressure device is 100 kPa, and the vacuum vessel has a volume of 38 ml. The time for 1 mL of air to flow, that is, the time (seconds) until the pressure inside the vessel changes from 50.7 kPa to 48.0 kPa, is measured. 10 times the obtained number of seconds was taken as the air leakage index. The sample size of the test film was 70 mm square, and 20 test films were laminated so that the front and back sides of the test film overlapped to obtain a laminated film for test.
A hole with a diameter of 5 mm was made in the center of the laminated film for testing, and the air leakage index was measured as described above. The larger the value of this air leakage index, the longer it takes for air to leak from the gaps between the films, so it indicates that the films are in closer contact, and the risk of wrinkles when made into a roll film. is large.

<Materials used>
Polyesters used in Examples and Comparative Examples are as follows.

[Polyester (A)]
100 parts by mass of dimethyl terephthalate and 65 parts by mass of ethylene glycol were charged into a transesterification reactor equipped with a stirrer, a heating device and a distillate separation tower, and heated to 150° C. to melt the dimethyl terephthalate.

Then, an ethylene glycol solution of magnesium acetate tetrahydrate was added so that the amount of magnesium acetate added to the obtained polyester was 0.09% by mass.
Thereafter, the temperature was raised to 225°C over 3 hours under normal pressure, and the mixture was further stirred and held at 225°C for 1 hour and 15 minutes, and the transesterification reaction was carried out while distilling off methanol to substantially complete the transesterification reaction. A polyester low polymer (oligomer) was obtained.

The oligomer was then transferred to a stirred polycondensation reactor equipped with a distillation tube.
An ethylene glycol solution of magnesium acetate tetrahydrate was added to the transferred oligomer so that the amount of magnesium acetate added to the obtained polyester resin content was 0.09% by mass.
Thereafter, an ethylene glycol solution of phosphoric acid was added as a heat stabilizer so that the amount of phosphoric acid added to the resulting polyester was 0.017% by mass.

Then, an ethylene glycol solution of tetrabutyl titanate as a polycondensation catalyst was added to the oligomer so that the amount of titanium atoms in the obtained polyester was 4.5 ppm by mass.
After that, the pressure was reduced from 101.3 kPa to 0.4 kPa in 85 minutes, and the pressure was maintained at 0.4 kPa. was performed to obtain a polyester A having an intrinsic viscosity (IV) of 0.63 dL/g.

[Polyester (B)]
0.75% by mass of alumina particles having an average particle size of 0.05 μm are added to the polyester (A) and kneaded using a vented twin-screw kneader to obtain a polyester having an intrinsic viscosity (IV) of 0.63 dL / g. (B) was obtained.

[Polyester (C)]
Instead of adding tetrabutyl titanate in polyester (A), polyester (A) except that antimony trioxide is added as a polycondensation catalyst so that the amount of antimony atoms is 300 ppm by mass with respect to the polyester resin content obtained. In the same manner as above, a polyester (C) having an intrinsic viscosity (IV) of 0.63 dl/g was obtained.

Resin compositions obtained by stirring and mixing the compositions shown in Table 1 below were diluted with water to prepare coating solutions 1 to 17. The compounds used are as follows.

[Compound (A): binder resin (IA)]
Aqueous dispersion of polyester resin copolymerized with the following composition Monomer composition: (acid component) terephthalic acid/isophthalic acid/5-sodium sulfoisophthalic acid // (diol component) ethylene glycol/1,4-butanediol/diethylene glycol = 56/40/4//70/20/10 (mol%)

[Compound (A): binder resin (IB)]
Aqueous dispersion of acrylic resin polymerized with the following composition Emulsion polymer of ethyl acrylate/n-butyl acrylate/methyl methacrylate/N-methylolacrylamide/acrylic acid = 65/21/10/2/2 (mass%) (emulsifier: anionic surfactant)

[Compound (A): binder resin (IC)]
An aqueous dispersion of a polyester-based urethane resin polymerized with the following composition.
Isophorone diisocyanate unit: terephthalic acid unit: isophthalic acid unit: ethylene glycol unit: diethylene glycol unit: dimethylolpropionic acid unit = 12:19:18:21:25:5 (mol%).

[Compound (A): Crosslinking agent (IIA)]
Melamine compound: Hexamethoxymethylol melamine

[Compound (B): Particle (IIIA)]
Zirconium oxide particles with an average particle size of 14 nm

[Compound (B): Particle (IIIB)]
Titanium oxide particles with an average particle size of 15 nm

[Compound (B): Particle (IIIC)]
Spherical silica particles with an average particle size of 5 nm

[Compound (B): Particle (IIID)]
Spherical silica particles with an average particle size of 11 nm

[Compound (B): Particle (IIIE)]
Spherical silica particles with an average particle size of 25 nm

[Compound (B): Particles (IIIF)]
Chain silica particles with an average particle size of 12 nm

[Compound (B): Particle (IIIG)]
Spherical silica particles with an average particle size of 45 nm

(Example 1)
A mixed raw material obtained by mixing polyesters (A) and (B) at a ratio of 87% by mass and 13% by mass, respectively, is used as a raw material for the outermost layer (A layer) on one side, and polyester (A) alone is used as a raw material for the intermediate layer (B layer). , and polyester (A) alone was used as a raw material for the outermost layer (C layer) on one side. Each of the raw materials for the A layer, B layer, and C layer is supplied to three extruders, melted at 280 ° C., and then placed on a cooling roll set at 25 ° C., three layers of two types (surface layer / intermediate layer / An unstretched sheet was obtained by co-extrusion with a layer structure of surface layer = 1.6/27.8/1.6 discharge amount) and solidification by cooling.
Next, this film was stretched 3.5 times in the longitudinal direction while being passed through a group of heating rolls at 86° C. to obtain a uniaxially stretched film. On one side of this uniaxially stretched film (the surface of layer C), a coating liquid 1 having the composition shown in Table 1 below was applied in a coating amount (after dry stretching) of 0.12 g/m ² , and then this film was stretched using a tenter stretching machine. , stretched 4.5 times in the width direction at 105 ° C., further subjected to heat treatment at 230 ° C., then subjected to 2% relaxation treatment in the width direction, and a thickness having a resin layer on the surface of the C layer of polyester film A A laminated polyester film with a thickness of 31 μm was obtained. Table 2 shows the evaluation results.

(Examples 2-3)
A laminated polyester film was obtained in the same manner as in Example 1, except that the coating liquid shown in Table 1 was used and the coating amount (after drying and stretching) was changed to that shown in Table 2. Table 2 shows the evaluation results.

(Example 4)
In the same manner as in Example 1, except that only the polyester (A) was used as the raw material for the outermost layer (A layer) on one side, and only the polyester (C) was used as the raw material for the intermediate layer (B layer), the surface of the layer C of the polyester film B A laminated polyester film having a resin layer was obtained. Table 2 shows the evaluation results.

(Examples 5-19)
A laminated polyester film was obtained in the same manner as in Example 4 except that the coating liquid shown in Table 1 was used and the coating amount (after drying and stretching) was changed to that shown in Table 2. Table 2 shows the evaluation results.

(Comparative example 1)
A polyester film was obtained in the same manner as in Example 1, except that the resin layer was not provided. Table 2 shows the evaluation results.

(Comparative example 2)
A polyester film was obtained in the same manner as in Example 4, except that the resin layer was not provided. Table 2 shows the evaluation results.

(Comparative Examples 3-5)
A laminated polyester film was obtained in the same manner as in Example 4 except that the coating liquid shown in Table 1 was used and the coating amount (after drying and stretching) was changed to that shown in Table 2. Table 2 shows the evaluation results.

Regarding the uneven shapes in Table 2, shape 1 is a mesh shape (see FIG. 1), shape 2 is a mixed mesh shape and uneven shape (see FIG. 2), and shape 3 is an uneven shape (see FIG. 3). indicates that it was
In Table 2 above, the polyester film A is the polyester film of Example 1, and the polyester film B is the polyester film of Example 4.

As the results in Table 2 show, Examples 1 to 19, which are laminated polyester films of the present invention, form an uneven structure by containing the compound (A) and a certain amount or more of (B), and kurtosis ( Sku) of less than 3.0 results in an appropriate uneven shape, a low coefficient of static friction of 1.0 or less, good slipperiness, and an air leakage index of 130,000 seconds or less, which is excellent in air release. It can be seen that the film is excellent in productivity such as removability. In addition, since the arithmetic mean roughness (Sa) and the maximum peak height (Sp) of the opposite surface of the resin layer were low, the film was an excellent film capable of precise processing.
On the other hand, Comparative Examples 1 and 2 do not have an uneven structure because they do not have a resin layer. Moreover, although Comparative Example 3 contains compound (A) and a certain amount or more of compound (B), it has a high kurtosis (Sku) value and does not have an appropriate concave-convex structure. Therefore, although the coefficient of static friction was low, the film had a high air leakage index and poor handleability. Moreover, since Comparative Examples 4 and 5 do not contain a certain amount or more of the compound (B), no concave-convex structure is formed. Therefore, these comparative examples were films with high coefficient of friction and air leakage index, poor slip properties and air release properties, and poor handleability.

Since the laminated polyester film of the present invention can form a fine uneven structure on the surface of the resin layer, for example, if it is used for sheet molding, even when an extremely smooth film is wound into a roll, good windability can be obtained. There is an advantage that it is effective and wrinkles are less likely to occur.
In addition, since the resin layer of the laminated polyester film of the present invention can be made into a thin film, the polyester film can be made thin and long, and it can contribute to productivity improvement by reducing the frequency of switching product rolls during processing. can.
Therefore, the laminated polyester film of the present invention can be suitably used as a sheet forming polyester film or the like having excellent surface smoothness, and its industrial utility value is high.

Claims (10)

A laminated polyester film comprising a polyester film and a resin layer formed of a resin composition on at least one side of the polyester film, wherein the laminated polyester film satisfies all of the following requirements (1) to (4).
(1) The resin layer has an uneven structure.
(2) The resin composition contains the following compounds (A) and (B).
(A) one or more selected from the group consisting of a binder resin and a cross-linking agent; (B) particles; % by mass or more.
(4) Kurtosis (Sku) of the surface of the resin layer is less than 3.0. The laminated polyester film according to claim 1, wherein the resin layer surface has an arithmetic mean roughness (Ra) of 10 nm or more when measured with a scanning probe microscope. The laminated polyester film according to claim 1 or 2, wherein the resin layer surface has a ten-point average roughness (Rzjis) of 60 nm or more when measured with a scanning probe microscope. Any one of claims 1 to 3, wherein the load length ratio (Rmr(70)) of the roughness curve at a cutting level of 70% of the resin layer surface measured with a scanning probe microscope is 82% or less. The laminated polyester film according to Item. The laminated polyester film according to any one of claims 1 to 4, wherein the resin layer surface has a root-mean-square gradient (Sdq) of 0.1 or more. The laminated polyester film according to any one of claims 1 to 5, wherein the resin layer surface has a developed interface area ratio (Sdr) of 0.5% or more. The laminated polyester film according to any one of Claims 1 to 6, which has an air leakage index of 130,000 seconds or less. The laminated polyester film according to any one of claims 1 to 7, wherein the particles (B) have an average particle size of 1 to 100 nm. The laminated polyester film according to any one of claims 1 to 8, wherein the (A) binder resin contains one or more selected from the group consisting of polyester resins, (meth)acrylic resins and polyurethane resins. The laminated polyester film according to any one of claims 1 to 9, wherein the (B) particles contain one or more selected from the group consisting of zirconium oxide, titanium oxide and silica.