TWI710587B - Polyester film - Google Patents

Abstract

The polyester film provided by the present invention has a ratio of optical density to thickness (μm) (optical density (OD)/thickness (T)) of 0.22 or more and 2.0 or less, depending on the melting state during differential scanning calorimetry (DSC) After being kept for 5 minutes and then cooling at a cooling rate of 10°C/min, the cooling crystallization temperature Tmc has a sharp peak in the range of 180°C or more and 210°C or less, thereby the hiding and film forming properties of the polyester film of the present invention Both are excellent and shrink when exposed to light, making it suitable as a light-shielding substrate for electronic devices.

Description

Polyester film

The present invention relates to a polyester film having excellent hiding properties and film forming properties, and also excellent shrinkage when exposed to light.

Polyester (especially polyethylene terephthalate, polyethylene 2,6-naphthalene dicarboxylate, etc.) resins are excellent in mechanical properties, thermal properties, chemical resistance, electrical properties, and moldability. It is used for various purposes. This polyester filmed polyester film, among which biaxially oriented polyester film, is used in solar battery backplane materials, electric insulation materials for water heater motors, and hybrid vehicles from the viewpoints of mechanical and electrical properties. Electrical insulating materials such as automotive air-conditioning motors or drive motors; tape materials or capacitor materials, packaging materials, construction materials, photo applications, drawing applications, thermal transfer applications, and other applications.

Among these applications, materials for solar battery backplanes or tape materials used inside electronic devices require concealment. For example, in the material for the solar battery back sheet, it is preferable that the wiring of the power generating element is not seen from the outside from the viewpoint of design. In the materials for solar battery backsheets, a review to improve the hiding properties is to adopt a method of using polyester films containing black pigments such as carbon black (Patent Documents 1 and 2). In addition, among tape materials, with the spread of smartphones in recent years, tapes used inside electronic devices require high concealment in order to shield internal light. With the miniaturization and thinning of electronic equipment, tape materials are not only required to be hidden, but also required to be thin films. In the tape material, as a There is a method to improve the hiding property, which aims at providing a printing layer containing more black pigment on a thin polyester film with a thin film thickness (Patent Document 3).

[Prior Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. 2008-56871

Patent Document 2: Japanese Patent Laid-Open No. 2011-119651

Patent Document 3: Japanese Patent No. 5651012

However, as described in the methods described in Patent Documents 1 and 2, if carbon black is added in order to impart hiding properties to the polyester, the carbon black becomes a nucleus for crystallization and accelerates the crystallization rate of the polyester. Therefore, if a large amount of carbon black is contained Then there will be a problem of reduced film forming properties. Therefore, the methods described in Patent Documents 1 and 2 limit the concentration of carbon black contained in the thin film, and therefore have a problem that sufficient hiding properties cannot be obtained. This problem is particularly prominent in thin-film thin films. On the other hand, the method described in Patent Document 3 can obtain sufficient hiding properties even in a thin film, but there is a problem of environmental pollution caused by printing ink; or due to the excellent mechanical properties of the polyester film thickness ratio It is small, so there is a problem of film shrinkage caused by heat generated when absorbing light.

The subject of the present invention is in view of these conventional technologies and provides: excellent hiding properties (hereinafter sometimes referred to as light-shielding properties) and film forming properties, and shrinkage when exposed to light (hereinafter sometimes referred to as light-resistant shrinkage) Also excellent polyester film.

In order to solve the above-mentioned problems, the present invention has the following configuration. which is,

[I] A polyester film, the ratio of optical density to thickness (optical density (OD)/thickness (T)) is 0.22 or more and 2.0 or less, and the cooling crystallization temperature Tmc of differential scanning calorimetry (hereinafter referred to as DSC) is Above 180°C and below 210°C.

[II] The polyester film according to [I], wherein the black pigment system contains 4% by mass or more and 25% by mass or less.

[III] The polyester film as described in [I] or [II], wherein the ten-point average roughness Rz (μm) of at least one surface is the ratio of Rz (μm) to the thickness (μm) (ten-point average roughness (Rz)/thickness (T)) is 0.30 or less.

[IV] The polyester film according to any one of [I] to [III], wherein the polyester resin system constituting the film contains a phthalic acid component and/or cyclohexane dimethanol as the polyester constituent components ingredient.

[V] The polyester film as described in [IV], wherein the polyester constituting the film contains 0.5 mol% or more and 20 mol% or less of the isophthalic acid component relative to the total dicarboxylic acid component, or relative to the total glycol component Contains 0.5 mol% or more and 20 mol% or less of cyclohexane dimethanol components.

[VI] The polyester film according to any one of [I] to [V], wherein the film thickness is 28 μm or less.

[VII] The polyester film described in any one of [I] to [VI] is used as a light-shielding substrate for electronic equipment.

[VIII] A shading tape using the polyester film described in any one of [I] to [VI].

According to the present invention, it is possible to provide a polyester film having excellent hiding properties and film forming properties, and excellent light shrinkage resistance. In addition, the film can be suitably used as a light-shielding substrate used in electronic equipment.

The polyester film of the present invention has a polyester resin as a main component. Here, the polyester resin as the main constituent component means that the polyester resin contains 60% by mass or more with respect to the components constituting the film.

The polyester resin constituting the polyester film of the present invention is composed of 1) dicarboxylic acid or its ester-forming derivative (hereinafter collectively referred to as "dicarboxylic acid component") and glycol component or its ester-forming derivative (hereinafter collectively referred to as The polycondensation of the "diol component"); 2) the polycondensation of a compound having a carboxylic acid or a carboxylic acid derivative and a hydroxyl group in one molecule; and a combination of 1) and 2) can be obtained. In addition, the polymerization system of the polyester resin can be carried out by a conventional method.

烯二羧酸、環己烷二羧酸、十氫萘二羧酸等脂環族二羧酸；對苯二甲酸、間苯二甲酸、鄰苯二甲酸、1,4-萘二羧酸、1,5-萘二羧酸、2,6-萘二羧酸、1,8-萘二羧酸、4,4'-二苯基二羧酸、4,4'-二苯醚二羧酸、4,4'-二苯碸二羧酸、5-磺酸鈉間苯二甲酸、苯基二氫茚二羧酸、蒽二羧酸、菲二羧酸、9,9'-雙(4-羧苯基)茀酸等芳香族二羧酸；或其酯衍生物等。又，該等係可單獨使用，亦可使用複數種。 In 1), representative examples of dicarboxylic acid components include, for example, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, dimer acid, and dimer acid. Aliphatic dicarboxylic acids such as dodecanedioic acid, pimelic acid, azelaic acid, methylmalonic acid, ethylmalonic acid; adamantanedicarboxylic acid,

Alicyclic dicarboxylic acids such as ene dicarboxylic acid, cyclohexane dicarboxylic acid, and decahydronaphthalene dicarboxylic acid; terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalene dicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 4,4'-diphenyl dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid , 4,4'-diphenyl dicarboxylic acid, 5-sodium sulfonate isophthalic acid, phenylindane dicarboxylic acid, anthracene dicarboxylic acid, phenanthrene dicarboxylic acid, 9,9'-bis(4 -Aromatic dicarboxylic acids such as carboxyphenyl) cinnamon acid; or ester derivatives thereof. In addition, these systems can be used alone or in plural.

Furthermore, at least one carboxyl terminal of the above-mentioned dicarboxylic acid component may be used to make oxyacids such as I-lactide, d-lactide, and paraben and their derivatives, or a plurality of oxyacids It is a dicarboxy compound formed by the condensation of those connected.

Secondly, representative examples of glycol components include, for example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, 1,3-butane Aliphatic diols such as diols; alicyclic diols such as cyclohexanedimethanol, spirodiol and isosorbide; bisphenol A, 1,3-benzenedimethanol, 1,4-benzenedimethanol, 9, Aromatic diols such as 9'-bis(4-hydroxyphenyl) pyridium. In addition, these systems may be used alone, or plural types may be used as needed. In addition, a dihydroxy compound formed by condensing diols at at least one hydroxy terminal of the above-mentioned diol component can also be used.

Furthermore, in 2), examples of compounds having a carboxylic acid or a carboxylic acid derivative and a hydroxyl group in one molecule include, for example, oxo acids such as I-lactide, d-lactide, and paraben and their derivatives ; Oxyacid oligomers; One carboxyl group of dicarboxylic acid is condensed with oxygen acid and so on.

Furthermore, the polyester resin constituting the polyester film of the present invention may also contain trifunctional components (carboxylic acids with three or more valences, diols with three or more valences, and diols with three or more valences, within the range that does not impair the characteristics of the invention. Oxyacids and their ester-forming derivatives).

Specific examples of polyester resins include polyethylene terephthalate, polyethylene 2,6-naphthalate, polytrimethylene terephthalate, polybutylene terephthalate, Homopolymers such as polylactic acid, and such copolymers, and the polyester resin constituting the polyester film of the present invention can also be used by selecting one of the above-mentioned homopolymers and copolymers. , Or blending homopolymer and copolymer.

Here, the homopolymer of the polyester resin is preferably polyethylene terephthalate, polyethylene 2,6-naphthalate, polybutylene terephthalate, and Polylactic acid, among them, from the viewpoint of easy processability, more preferred are polyethylene terephthalate and polyethylene 2,6-naphthalate, and from the viewpoint of more excellent film forming properties, particularly preferred Ethylene phthalate.

Furthermore, the so-called copolymer of polyester resin refers to a copolymer composed of one or both of different dicarboxylic acid components and glycol components of less than 50 mol% of the total polyester resin. In the case of polymer blending, it is preferable to use a copolymer having the same molecular structure as the target homopolymer and accounting for more than 50 mol% of the total.

The copolymer of the polyester resin here is preferably an alicyclic dicarboxylic acid containing a dicarboxylic acid component as a copolymerization component from the viewpoints of excellent polymerization suitability, thermal stability, and excellent compatibility with the homopolymer , Isophthalic acid, naphthalenedicarboxylic acid, and butanediol, ethylene glycol, spirodiol, and cyclohexane dimethanol as the diol component, these systems can be used alone or in combination as needed. Among them, from the viewpoint of improving film forming properties, it is more preferable to use cyclohexane dimethanol containing dicarboxylic acid component as a copolymer component, or diol component as a copolymer component.

In the polyester resin constituting the polyester film of the present invention, the ratio of the copolymerization component relative to the total polyester resin component is preferably adjusted to be 0.5 mol% or more and 20 mol% or less, and the copolymer and homopolymer are adjusted The blending ratio of each other, or homopolymer and copolymer. By introducing a copolymerization component into a polyester resin, the crystallinity of the polyester is reduced, and even if a large amount of the coloring pigment described later is contained, a polyester film having excellent film formability and light shrinkage resistance can be obtained. The ratio of the copolymerization component is more preferably 1.0 mol% or more and 15 mol% or less, still more preferably 2.0 mol% or more and 10 mol% or less, and particularly preferably 2.5 mol% or more and 7.5 mol% or less.

The so-called copolymerized component here means that when the dicarboxylic acid component and the diol component of the polymer composed of more than 50 mol% of the polyester resin are used as the first component, the polyester resin contains less than 50 mol% Dicarboxylic acid components and glycol components other than the first component. In addition, the polyester film, which is the copolymer component of the polyester film, can be analyzed by proton nuclear magnetic resonance spectroscopy ( ¹ H-NMR) or carbon nuclear magnetic resonance spectroscopy ( ¹³ C-NMR) after solvent extraction.

If the ratio of the copolymerization component of the polyester resin is less than 0.5 mol%, the crystallinity may not be inhibited, resulting in insufficient film formability, or excessive alignment during stretching may also reduce the light shrinkage resistance. On the other hand, if the copolymerization component ratio of the polyester resin exceeds 20 mol%, the crystallinity of the polyester resin is too low, which may cause the film-forming properties to decrease, or the mechanical strength may be insufficient due to the lack of alignment. The heat generated when irradiated with light causes excessive shrinkage of the film, resulting in insufficient light shrinkage resistance. That is, in the polyester resin constituting the polyester film of the present invention, by setting the ratio of the copolymerization component relative to the total polyester resin component to be 0.5 mol% or more and 20 mol% or less, it is possible to form a more excellent film forming property and light shrinkage. Sexual polyester film. In addition, the copolymerization component contains 0.5 mol% or more and 20 mol% or less of isophthalic acid component relative to the total dicarboxylic acid component, or contains 0.5 mol% or more and 20 mol% cyclohexane dimethanol component relative to the total diol component. % Or less, the film forming properties and light shrinkage resistance of the polyester film can be improved, so it is better.

In addition, the polyester resin constituting the polyester film of the present invention is preferably a crystalline polyester resin from the viewpoint of biaxial stretchability. The so-called crystallinity here refers to the polyester film in accordance with JIS K7122 (1987), using differential scanning calorimetry to measure the heating rate from a solid state to a molten state of 10 ℃ / min, obtained in the figure, there is observed thermal crystallization Endothermic spikes caused by chemistry.

In order to impart hiding properties, the polyester film of the present invention preferably contains a coloring pigment. The color pigment is preferably a black pigment from the viewpoint of excellent light-shielding properties. Specifically, black pigments include carbon-based compounds such as carbon black, graphite, fullerene, and carbon fiber; or oxide-based inorganic particles such as titanium black. Moreover, it is preferable to use carbon black from the viewpoint of compatibility of hiding properties and film forming properties, and among them, it is more preferable to use carbon black manufactured by the furnace method from the viewpoint of being inexpensive and excellent in hiding properties.

The particle diameter of the color pigment is preferably 5 nm or more and 100 nm or less, more preferably 10 nm or more and 50 nm or less, and still more preferably 15 nm or more and 30 nm or less in terms of primary particle diameter. If the primary particle diameter of the color pigment is less than 5 nm, defects may occur due to aggregation, or the crystallization of the polyester resin may be excessively promoted, and the film-forming properties may decrease. On the other hand, if the primary particle diameter of the colored pigment exceeds 100 nm, the hiding property may be reduced, or the film may be easily broken during film formation.

Furthermore, the content of the color pigment is preferably 0.5% by mass or more and 40% by mass or less. When the coloring pigment of the present invention contains a black pigment, it is preferably 3.5% by mass or more and 30% by mass or less, more preferably 4.0% by mass or more and 25% by mass or less, particularly preferably 5.0% by mass or more and 15% by mass Below, the best is 6.0% by mass or more and 10% by mass or less. If the content of the black pigment of the present invention is less than 3.5% by mass, the shading properties may not be satisfied due to insufficient hiding properties. On the other hand, if the content of the black pigment exceeds 30% by mass, the film formability may decrease. That is, by making the polyester film of the present invention contain a black pigment of 3.5% by mass or more and less than 30% by mass, even a thin film with a film thickness of 28 μm or less can achieve both excellent hiding properties and film forming properties.

Furthermore, the polyester film of the present invention may contain other additives (for example, heat-resistant stabilizers, ultraviolet absorbers, weather stabilizers, organic slip agents, fillers, etc.) within the range that does not impair the effects of the present invention. , Antistatic agent, flame retardant, etc.). For example, when the polyester film of the present invention is used for applications that require flame retardancy, it can be obtained by containing organic flame retardants such as halogen or phosphorus, or inorganic flame retardants such as antimony or metal hydroxide. Improve the flame retardancy of polyester film. In addition, even if a flame retardant is used in combination with a coloring pigment, it is preferable to use an organic flame retardant from the viewpoint of maintaining the film-forming properties, and from the viewpoint of reducing the environmental load, it is more preferable to use a phosphorus flame retardant among the organic flame retardants. Agent.

The polyester film of the present invention must have a differential scanning calorimetry (DSC) cooling crystallization temperature Tmc of 180°C or more and 210°C or less. It is more preferably 186°C or higher and 206°C or lower, particularly preferably 192°C or higher and 203°C or lower, and most preferably 197°C or higher and 201°C or lower. The so-called cooling crystallization temperature Tmc of the differential scanning calorimeter here means that the polyester film is heated from 25°C to the melting point Tm+50°C of the polyester resin at a temperature increase rate of 10°C/min in accordance with JIS K7122 (1987). At the melting point Tm+50°C, the polyester resin is kept in the molten state for 5 minutes, and then cooled to 25°C at a cooling rate of 10°C/min. The peak top temperature of the heating peak obtained at 25°C. In addition, when there is a heating peak in plural, it refers to the peak top temperature on the highest temperature side. The melting point Tm of the polyester resin here is measured on the polyester film using differential scanning calorimetry. The graph is obtained when heating from a solid state to a molten state at a heating rate of 10°C/min. The endothermic peak is obtained on the highest temperature side. temperature. The above-mentioned cooling crystallization temperature Tmc is used as an indicator of the crystallinity of the polyester resin. If the temperature of the cooling crystallization temperature Tmc is higher, the crystallinity is higher. If the temperature of the cooling crystallization temperature Tmc is lower, or not detected If the cooling crystallization temperature Tmc is exceeded, the crystallinity is low.

In the polyester film of the present invention, when the cooling crystallization temperature Tmc is less than 180°C, the crystallinity is too low. Therefore, when a high concentration of black pigment is contained, the film shrinks during light irradiation or stretches. The problem of reduced stretchability due to warpage of the film arises. In particular, this problem is more pronounced in thinner films with a film thickness of 28 μm or less. On the other hand, if the cooling crystallization temperature Tmc exceeds 210°C, the crystallinity becomes too high, and thus film formation tends to be difficult. In addition, alignment is easily applied, and the light shrinkage resistance is reduced due to residual stress after stretching. That is, in the present invention, by setting the cooling crystallization temperature Tmc to a range of 180° C. or more and 210° C. or less, a polyester film having both excellent film formability and light shrinkage can be obtained.

Furthermore, the cooling crystallization temperature Tmc of the present invention can be adjusted by the type or content of the coloring pigment and the copolymerization component ratio in the polyester resin when the polyester resin constituting the polyester film contains a coloring pigment. In addition, in order to take into account hiding properties, it is best to adjust the ratio of the copolymerization components in the polyester resin.

Even though the polyester film of the present invention is a film, it is excellent in hiding properties, film forming properties, and light shrinkage. Therefore, it can be suitably used as a tape substrate used in electronic devices such as smartphones that require thinness.

The thickness (T) of the polyester film of the present invention is preferably 28 μm or less, more preferably 25 μm or less, particularly preferably 20 μm or less, and most preferably 16 μm or less. In addition, the lower limit of the thickness is not particularly limited, but from the viewpoint of a concern about a decrease in film formability or deterioration in light shrinkage, it is actually 3.0 μm or more.

Furthermore, the optical density (OD) of the polyester film of the present invention is preferably 3.5 or higher, more preferably 4.0 or higher, particularly preferably 5.0 or higher, and most preferably 6.0 or higher. By setting the optical density (OD) of the polyester film of the present invention to 3.5 or higher, it can be applied as a tape base material that requires light-shielding properties used in electronic devices that generate light inside. In addition, when the base film is used as a light-shielding tape, the number of times of printing of the black ink layer can be reduced. In addition, the upper limit of the optical density is not particularly limited, but from the viewpoint of the amount of particles that can be contained in the film, it is actually 9.0 or less.

The ratio of optical density to thickness (μm) (optical density (OD)/thickness (T)) of the polyester film of the present invention must be 0.22 or more and 2.0 or less. The optical density, which represents an index of the concealment of the film, can also be understood from the Lambert-Beer law. The thicker the film thickness (the longer the optical path of light passes through), the higher the value tends to be. Therefore, if only the optical density is increased, from the viewpoint of film formability or light shrinkage, even if the film can contain a conventional polyester film with a limited amount of colored pigments, it can still be achieved by increasing the film thickness. However, from From the viewpoint of film formability or light shrinkage, conventional polyester films with limited amounts of coloring pigments can be contained in the film, and it is difficult to set the ratio (OD/T) of optical density to thickness (μm) to 0.22 or more. As mentioned above, the polyester film of the present invention can contain coloring pigments in a high concentration by controlling the crystallinity in an appropriate range, and can achieve the ratio of optical density to thickness (μm) (OD /T) 0.22 or more, preferably 0.25 or more and 1.5 or less, more preferably 0.30 or more and 1.0 or less, particularly preferably 0.35 or more and 0.5 or less.

In the present invention, a polyester film having an optical density to thickness (μm) ratio (OD/T) of less than 0.22 indicates that although the thickness is thick, the hiding property is insufficient. On the other hand, if the ratio (OD/T) of the optical density to the thickness (μm) exceeds 2.0, it is thinner and has excellent hiding properties, but on the other hand, the film-forming properties are reduced, and the light is absorbed when light is irradiated. The heat caused the film to shrink excessively, so it is not suitable as a substrate used in electronic equipment.

That is, by setting the optical density to thickness (μm) ratio (OD/T) of the polyester film of the present invention within the range of 0.22 or more and 2.0 or less, even the film can be excellent in light-shielding properties, film forming properties, A film with excellent light shrinkage. Therefore, it can be used as a tape substrate in electronic devices that require thinness and light-shielding properties, such as smart phones.

The ten-point average roughness Rz (μm) of at least one surface of the polyester film of the present invention is preferably 3.0 μm or less, more preferably 2.5 μm or less, particularly preferably 2.0 μm or less. The ten-point average roughness Rz here refers to the ten-point average roughness Rz value of at least one surface of the polyester film measured by a contact three-dimensional surface roughness meter in the measurement method described later. If the ten-point average roughness Rz exceeds 3.0 μm, the unevenness of the surface is too large, and the thickness of the film necessary for light shielding may be increased. In addition, there is no particular limitation on the lower limit of the ten-point average roughness Rz, but from the viewpoint of a concern about a reduction in the coilability, it is preferably 0.1 μm or more. In addition, it is more preferable that the ten-point average roughness Rz (μm) on both surfaces of the film is full Full of the above range.

The ten-point average roughness Rz (nm) of at least one surface of the polyester film of the present invention preferably satisfies the ratio of Rz (μm) to thickness (μm) (ten-point average roughness (Rz)/thickness (T)) 0.30 or less, more preferably 0.25 or less, and particularly good or less 0.20. If (Rz/T) exceeds 0.30, the unevenness of the surface is too large, resulting in insufficient film thickness necessary for light shielding, and the light shielding property may be reduced. In addition, the surface irregularities become too large with respect to the film thickness, and the film formability may decrease. In addition, the lower limit of (Rz/T) is not particularly limited. From the viewpoint of improving light-shielding properties by utilizing light diffusion on the film surface, it is preferably 0.07 or more, more preferably 0.10 or more, and particularly preferably 0.12 or more.

When the ten-point average roughness Rz (μm) to thickness (μm) ratio (Rz/T) of the polyester film of the present invention is set to 0.30 or less, when the polyester resin constituting the polyester film contains a colored pigment, The ten-point average roughness Rz (μm) can be adjusted using the film forming conditions of the polyester film. Details will be described later.

The polyester film system of the present invention may be a single film film, or any structure including two or more laminated films may be selected. By setting the polyester film of the present invention as a single film film, the manufacturing steps can be simplified. In the case of a two-layer or more laminated film, the P2 layer/P1 layer/P2 layer is used for two types of three layers. For example, the P2 layer is a layer that does not contain coloring pigments, and the P1 layer is set to contain The layer of coloring pigment is separated by function to create a film with both hiding and new functions. In addition, by making the P2 layer contain a coloring pigment and making the P1 layer contain a light-diffusing cavity, the light-shielding property can be further improved.

(Method of manufacturing polyester film)

Next, the method for producing the polyester film of the present invention will be described with specific examples. The present invention cannot be construed as being limited to what is obtained using this example.

First, the method for producing the polyester resin constituting the polyester film can be produced by the following method.

The polyester resin is obtained by subjecting a dicarboxylic acid or its ester derivative and a diol to a transesterification reaction or an esterification reaction by a known method. Examples of conventionally known reaction catalyst systems include alkali metal compounds, alkaline earth metal compounds, zinc compounds, lead compounds, manganese compounds, cobalt compounds, aluminum compounds, antimony compounds, titanium compounds, and phosphorus compounds. It is preferable to add an antimony compound, a germanium compound, or a titanium compound as a polymerization catalyst at any stage before the completion of the production method of the polyester resin. For this method, for example, if a germanium compound is used as an example, it is preferable to directly add the germanium compound powder.

Secondly, the method of manufacturing polyester film is preferably a method of heating and melting the raw materials constituting the polyester film in an extruder, and then extruding it from a spinneret onto a cooled casting drum to process it into a sheet ( Melt casting method). In addition, in the case of a polyester film with a laminated structure, it is preferable to put the raw materials of the laminated layers into two extruders, melt them, and merge them, and then co-extrude them from the spinneret onto the cooled casting drum. The processing method is sheet-like (co-extrusion method). In addition, by statically contacting the melt-extruded sheet to the casting drum and cooling and solidifying, an unstretched sheet with suppressed crystallization can be produced. In addition, the method of making close contact with the casting drum can be selected from a method of blowing air from a narrow groove to the melt extruded sheet to make the sheet close, or a method of drawing the melt extruded sheet into close contact with a vacuum chamber.

Secondly, the polyester film of the present invention is preferably at least uniaxially stretched, more preferably biaxially stretched. By stretching to obtain the polyester film of the present invention, a polyester film that can be thinned and has excellent mechanical properties can be formed.

The stretching method is to guide the unstretched sheet to a set of rollers heated to a temperature of 70~140℃, extend it in the longitudinal direction (longitudinal direction, that is, the direction in which the sheet advances), and then cool it with a set of rolls at a temperature of 20-50℃ , You can get a uniaxial extension piece.

When performing biaxial stretching, the two ends of the uniaxial stretching sheet obtained as described above are then held by a clamp while guiding it to the tenter, and it is heated to a temperature of 70 to 150 ℃ in an environment at a right angle to the longitudinal direction. Stretching in the direction (width direction) to obtain a biaxially stretched polyester film.

At this time, the stretch magnification is set to 2 to 5 times in the longitudinal direction and the width direction respectively, and the area magnification (longitudinal stretch magnification × transverse stretch magnification) is preferably 8 times or more, more preferably 9 times or more, particularly good system More than 10 times. The lower limit of the area magnification is not particularly limited, but if it is less than 6 times, the mechanical properties of the film may be insufficient, or the film may be difficult to form.

The method of performing biaxial stretching can be a simultaneous biaxial stretching method in which the longitudinal direction and the width direction are separately performed in addition to the sequential biaxial stretching method described above, and the longitudinal direction and the width direction are simultaneously performed. , Or blown film.

Here, in order to adjust the ten-point average roughness Rz (μm) of the polyester film to a better range, it is better to select biaxial stretching, and more preferably to just before uniaxial stretching (in the case of simultaneous biaxial stretching) The film temperature is adjusted to the range of 80°C or higher and 100°C or lower just before the simultaneous stretching, and the stretching ratio of the first axis is 2.8 times or more and 3.6 times or less, or the second axis is extended The preheating temperature is set to 70°C or higher and 125°C or lower to form a film.

In order to reduce the ten-point average roughness Rz of the polyester film, it is important to suppress the formation of coarse crystals during stretching, so the Rz of the unstretched sheet or the uniaxially stretched sheet becomes larger. Also, if the stretching temperature during the first axis stretching exceeds 100°C, or if the stretching ratio is less than 2.8 times, the thermal crystallization of the polyester may be excessively promoted, and the ten-point average roughness Rz may increase. . In addition, when the stretching temperature is less than 80°C, or when the stretching magnification exceeds 3.6 times, the alignment crystallization of the first axis is excessively promoted. Also, Ruodi If the preheating temperature of the biaxial stretching exceeds 125°C, the crystals of the polyester formed on the first axis will grow due to heat and remain on the polyester film in the form of coarse crystals, causing the unevenness of the surface to increase. On the other hand, if the preheating temperature of the second axis stretching is less than 70°C, there may be insufficient heat and stretching cracks may occur.

That is, when the polyester film of the present invention is produced by biaxial stretching, the crystallization and crystal growth of the polyester can be suppressed by forming the film under the above-mentioned conditions, so that the ten-point average roughness Rz of the polyester film can be adjusted to The preferred range can further improve the light-shielding property of the polyester film.

The method of making the polyester film of the present invention contain coloring pigments is preferably to prepare the coloring pigments in high concentration as a masterbatch raw material, and when put into the extruder, use polyester resin that does not contain coloring pigments to dilute to the desired concentration Method (masterbatch method).

Furthermore, the present invention preferably uses a polyester resin copolymerized with a masterbatch base material. The masterbatch obtained according to this method can further improve the dispersibility of the colored pigments, and can improve the light-shielding properties and film forming properties.

The polyester film of the present invention can be manufactured according to the above-mentioned manufacturing method. The obtained polyester film has excellent hiding properties and film forming properties, and also excellent shrinkage when exposed to light. Therefore, it is of course suitable for light-shielding substrates used in electronic equipment, and can also be applied to industrial materials such as cover films, films for solar battery backplanes, and insulating films for motors; exterior films for lithium-ion batteries, design films, Packaging materials such as protective films; films for ribbons, films for construction materials, and thermal transfer films for various applications.

Furthermore, the light-shielding substrates for electronic equipment to which the polyester film of the present invention can be applied include, for example, mobile phones, smart phones, desktop PCs, notebook PCs, tablet PCs, electronic dictionaries, car navigation, GPS navigation, The base material of the shading sheet or shading tape used in the internal assembly of electronic equipment such as digital cameras and video cameras. By using the invention Polyester film can prevent the internal light from leaking out of the electronic equipment, and achieve a smaller size or thinner.

Since the polyester film of the present invention has excellent hiding properties and film forming properties, and also excellent shrinkage when exposed to light, it can be applied to light-shielding tapes. The light-shielding tape structure that can be used for the polyester film of the present invention includes, for example, one having an adhesive layer provided on one side or both sides of the polyester film of the present invention. The adhesive used in the adhesive layer is not particularly limited, and it is preferable to use an acrylic adhesive, a urethane adhesive, or the like.

When the light-shielding property of the light-shielding tape of the present invention is insufficient, the black ink layer can be arranged on the surface of the polyester film without the adhesive layer, or when the adhesive layer is provided on both sides, it can be arranged on the polyester film And between the adhesive layer. In addition, a black pigment may be mixed with an adhesive to form a black adhesive layer. The black ink component is not particularly limited, and it is preferable to include the aforementioned black pigment component in a binder made of acrylic resin or urethane resin.

Furthermore, within a range that does not impair the effect of the present invention, a functional layer containing other additives may be newly provided, or it may be combined with the above-mentioned adhesive layer or black ink layer. For example, by arranging a layer containing large particles on the polyester film on the opposite side of the adhesive layer, it can become a light-shielding tape with matting properties. In addition, by adding heat-dissipating particles to the black ink layer, it becomes a light-shielding tape with excellent heat dissipation.

Secondly, the method of providing the above-mentioned layer on the polyester film can be performed after surface treatment such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, primer coating, etc. Choose to implement coating methods such as roll coating, dip coating, bar coating, die coating, and gravure roll coating; or lithography, gravure, fast-drying, serigraphy, inkjet printing, etc. method. In addition, in the production of polyester film, from the viewpoint of simplification of the steps, the preferred method is to use a well-known coating in line. Method of cloth technique.

As described above, the light-shielding tape using the polyester film of the present invention, which is thin and excellent in light-shielding properties, does not have the conventional black ink layer used to impart light-shielding properties, or reduces the number of layers, so it can reduce the use of organic solvents. Environmental load caused by solvents or simplification of manufacturing steps.

〔Methods of measuring and evaluating characteristics〕 (1) Differential scanning calorimetry (DSC)

According to JIS K7122 (1987), the Seiko Instruments Inc. differential scanning calorimeter "Robot DSC-RDC220" is used, and the data analysis system uses Disk Session "SSC/5200", and 5 mg of polyester film is weighed in the sample pan , Heat from room temperature to 300°C according to the heating rate of 10°C/min (called 1stRUN), keep in this state for 5 minutes, and then cool to 25°C according to the cooling rate of 10°C/min to obtain the measurement of the heating process and cooling process Figure.

(1-1) Measurement of cooling crystallization temperature Tmc

Regarding the exothermic spike that appears during the temperature drop obtained in (1), the peak top temperature is set as the temperature drop crystallization temperature Tmc of the polyester film. In addition, when a plurality of heating peaks appear, the peak on the highest temperature side is set as the cooling crystallization temperature Tmc.

(2) Optical concentration measurement

The optical density of the polyester film was measured using a spectrodensity meter manufactured by X-lite Corporation. In the measurement system, a distance of 5 cm or more was selected on a straight line between the longitudinal direction and the width direction, and the measurement was performed 5 times, and the average value of 10 times in total was used as the optical density. In addition, when the direction is not clear, or when there is no concept, arbitrary direct On-line, and on a straight line in the vertical direction.

(3) Measurement of three-dimensional surface roughness Rz

The ten-point average roughness Rz of the polyester film is based on the three-dimensional surface roughness meter (model ET-4000A) manufactured by Kosaka Research Institute and the three-dimensional surface roughness analysis system (model TDA-31) manufactured by Kosaka Research Institute. The needle system is set to tip radius 0.5μmR, diameter 2μm, diamond made, needle pressure 100μN, and the measurement conditions are set to X spacing (measurement direction): 1.00μm, Y spacing (vertical to the measurement direction): 5μm, X feed Speed: 0.1mm/s, low point cutoff value: 0.25mm, high point cutoff value: R+W, measuring force: 100, Z measuring magnification: 20000, hysteresis: 0.006μm, set the measuring direction to the direction of the long side of the film In the width direction, the average value of the two measurements is taken as the three-dimensional surface roughness Rz. In addition, the measurement was performed on the two surfaces, and the three-dimensional surface roughness of the smaller value is described in the table. In addition, when the directionality is unclear, or when there is no concept, the measurement is performed on an arbitrary straight line and a straight line perpendicular to it.

(4) Film production

The film-forming properties of the polyester film are determined from the stretching ratio at which film breakage does not occur when the film is continuously formed for 1 hour, as follows. In addition, the longitudinal stretch and lateral stretch magnifications are both set to a minimum of 2.5 times or more, and the lateral stretch magnification here means the mechanical magnification of the ratio of the entrance width of the tenter to the maximum width. In addition, conditions other than the stretching ratio can be freely changed.

The surface magnification is more than 10 times: A

The surface magnification is more than 9 times: B

The surface magnification is more than 8 times: C

The surface magnification is more than 6 times: D

The area magnification is less than 6 times, or the film cannot be made: E

Film forming properties A to D are good, and A is the most excellent among them.

(5) Evaluation of shading (5-1) Production of simulated LED lighting stand for shading evaluation

光纖光導件，將LED光源本體的控制器刻度設為8，而準備LED照明。其次，從開設有光導件前端直徑尺寸孔的樣品台下部插入光導件(light guide)，固定成在距離樣品台平面部5mm位置處位於LED照明前端的狀態，而製作模擬LED照明台。 Connect the LED light source (type: LA-HDF108AS, rated voltage AC100~240V, rated power consumption 20W, rated frequency 50/60Hz) for optical fiber light guides manufactured by Linshiji Industrial Co., Ltd., with a bundle diameter of 4mm made by the same company

For the optical fiber light guide, set the controller scale of the LED light source body to 8 and prepare for LED lighting. Next, a light guide was inserted from the lower part of the sample stage with a diameter hole of the front end of the light guide, and the light guide was fixed at a position 5mm away from the flat surface of the sample stage at the front end of the LED lighting to produce a simulated LED lighting stage.

(5-2) Simulated light shading evaluation

Cover the polyester film on the simulated LED lighting table obtained in (5-1), visually confirm whether there is an LED light source penetrating the polyester film when adjusting the input voltage, and determine the light shielding property of the polyester film as follows. In addition, the above-mentioned evaluation was performed 5 times each at a distance of 5 cm or more on a straight line between the longitudinal direction and the width direction, and set as an average value of 10 times in total. Also, when the shape of the transmitted light is not circular, the length of the longest diameter is measured.

Even if the input voltage is 5V, the penetrating light is still invisible: A

If the input voltage is above 3V and less than 5V, no penetrating light can be seen: B

If the input voltage is above 2V and less than 3V, no penetrating light can be seen: C

If the input voltage is above 1V and less than 2V, no penetrating light can be seen: D

Even if the input voltage is less than 1V, the penetrating light is still visible: E

The light-shielding properties A to D are good, and A is the most excellent among them.

(6) Evaluation of light resistance shrinkage

Scribe a 1cm square on one side of the polyester film, use a TECHNO NEEDS (share) universal projector (AMM-1) to measure the length of the two diagonal lines, and average the length of the two Set to L0. Next, on the simulated LED lighting table used in (4), cover the polyester film so that the center of the square becomes the center of the LED lighting, set the input voltage to 5V, and irradiate the light for 30 seconds, and then measure 2 squares in the same way. The average value at the diagonal length is set to L, and the light shrinkage rate is calculated from the following formula. In addition, the above evaluation was performed five times on a straight line in the longitudinal direction and the width direction at a distance of 5 cm or more, and set as an average value of 10 times in total.

Light shrinkage (%)=(L0-L)/L0×100

From the obtained light shrinkage rate, the light shrinkage resistance of the polyester film was determined as follows.

Light shrinkage rate is less than 2%: A

Light shrinkage rate is more than 2% and less than 3%: B

Light shrinkage rate is more than 3% and less than 5%: C

Light shrinkage rate is more than 5% and less than 10%: D

Light shrinkage rate is more than 10%, or cannot be measured: E

The light shrinkage resistance series A to D are good, and among them, A is the most excellent.

(7) Required characteristics of light-shielding substrates for electronic equipment

The evaluation of the thickness of the polyester film, the light-shielding properties of (5), and the light shrinkage resistance of (6) was determined as follows.

The thickness is 16μm or less, and the light-shielding and light shrinkage resistance evaluations are judged to be A: A

The thickness is 20μm or less, and the light-shielding and light shrinkage resistance evaluations are judged to be B or more: B

The thickness is 25μm or less, and the light-shielding and light shrinkage resistance evaluations are judged to be C or more: C

The thickness is 28μm or less, and the light shielding and light shrinkage resistance evaluations are judged to be D or more: D

Either the thickness exceeds 28μm, or the evaluation of light-shielding and light-resistant shrinkage is judged as E: E

The light-shielding base materials for electronic devices A to D are good, and A is the most excellent among them.

(8) Printing times of black ink layer

The light-shielding tape using polyester film has achieved A in (5) Light-shielding evaluation (5-1) Simulated light-shielding evaluation. Therefore, the number of times the black ink layer is printed on the polyester film is judged as follows Evaluation. The evaluation system was performed 5 times and judged based on the average value.

No printing required: A

Printing times less than 2 times: B

Printing times more than 2 times but less than 4 times: C

Printing times more than 4 times but less than 6 times: D

Printing times is more than 6 times: E

In the light-shielding tape evaluation, from the viewpoint of reducing the environmental load or simplifying the manufacturing process, A to D are good, and among them, A is the most excellent.

[Example]

Hereinafter, the present invention will be described with some embodiments, but the present invention is not necessarily limited to these.

(Method of manufacturing polyester resin) 1. Polyethylene terephthalate (PET)

100 parts by mass of dimethyl terephthalate, 57.5 parts by mass of ethylene glycol, 0.03 parts by mass of magnesium acetate dihydrate, and 0.03 parts by mass of antimony trioxide were melted at 150°C in a nitrogen atmosphere. While stirring the melt, the temperature was increased to 230°C over 3 hours, methanol was distilled off, and the transesterification reaction was terminated. After the transesterification reaction is completed, an ethylene glycol solution (pH 5.0) in which 0.005 parts by mass of phosphoric acid is dissolved in 0.5 parts by mass of ethylene glycol is added. At this time, the inherent viscosity of the polyester composition is less than 0.2. Then, the polymerization reaction was performed at the final temperature of 285°C and the degree of vacuum of 0.1 Torr to obtain polyethylene terephthalate having an intrinsic viscosity of 0.65 and a terminal carboxyl group content of 34 equivalents/ton.

2. Polyethylene naphthalate (PEN)

Except that 2,6-naphthalenedicarboxylic acid is used as the dicarboxylic acid component, the others are polymerized in the same manner as the polyethylene terephthalate in item 1. above to obtain an intrinsic viscosity of 0.61 and 36 equivalents of terminal carboxyl groups. /Ton of polyethylene naphthalate.

3. Polyethylene terephthalate-IPA copolymer 1 (PET/I-1)

Except that the dicarboxylic acid component is mixed with 82.5 parts by mass of dimethyl terephthalate and 25 parts by mass of dimethyl isophthalate, the rest is the same as the polyethylene terephthalate in item 1. The polymerization was carried out locally, and a polyethylene terephthalate copolymerized with 17.5 mol% of isophthalic acid (IPA) was obtained.

4. Polyethylene terephthalate-IPA copolymer 2 (PET/I-2)

Except that the dicarboxylic acid component is mixed with 75 parts by mass of dimethyl terephthalate and 25 parts by mass of dimethyl isophthalate, the rest are polymerized in the same manner as polyethylene terephthalate to obtain isobenzene Dicarboxylic acid (IPA) 25mol% copolymerized polyethylene terephthalate.

5. Polyethylene terephthalate-NDC copolymer (PET/N)

Except that 2,6-naphthalenedicarboxylic acid is used as the dicarboxylic acid component, the rest are the same as the polyethylene terephthalate copolymer of item 3. above, to obtain 17.5 mol of naphthalenedicarboxylic acid (NDC) % Copolymerized polyethylene terephthalate.

6. Polyethylene terephthalate-CHDM copolymer (PET-G)

Polyethylene terephthalate copolymerized with 30 mol% cyclohexane dimethanol (CHDM) is a polyester resin "Eastar ^TM Copolyester 6763" manufactured by Eastman Chemical Company.

7. Polybutylene terephthalate (PBT)

The glycol component is polybutylene terephthalate with butanediol (BDO), and it uses "TORAYCON 1200S" manufactured by Toray Corporation.

8. CB masterbatch 1 (CB-MB1)

80 parts by mass of the polyethylene terephthalate obtained in item 1. above and 20 parts by mass of carbon black (CB-1) prepared by the furnace method with a primary particle size of 18nm were used in an extruder at 280°C under exhaust Melt kneading is performed inside to produce CB master batch 1.

9. CB masterbatch 2 (CB-MB2)

Except that carbon black (CB-2) manufactured by the acetylene method with a primary particle size of 23 nm was used, the CB masterbatch 2 was produced in the same manner as the CB masterbatch 1.

10. CB masterbatch 3 (CB-MB3)

Except that the basic polyester resin system uses the polyethylene terephthalate-IPA copolymer 1 obtained in item 3. above, the CB masterbatch 3 is produced in the same way as the CB masterbatch 1.

11. Titanium oxide master batch (TiO ₂ -MB)

50 parts by mass of the polyethylene terephthalate obtained in item 1. above and 50 parts by mass of rutile-type titanium dioxide particles with a primary particle size of 200 nm were melt-kneaded in an extruder at 280°C that was vented, and Make TiO ₂ masterbatch.

(Method of making shading tape) 1. Adhesive layer

98.9 parts by weight of isononyl acrylate, 0.1 parts by weight of acrylic acid, 1.0 parts by weight of N-vinylcaprolactam, 0.05 parts by weight of n-dodecyl sulfhydryl as a chain transfer agent, and 80 parts by weight of ethyl acetate as a solvent It was filled into a five-necked flask equipped with a stirrer, reflux cooling tube, thermometer, drip funnel, and nitrogen inlet. After stirring, it was flushed with nitrogen for about 30 minutes to remove oxygen remaining in the monomer solution. Then, the air in the flask was replaced with nitrogen, the temperature was raised while stirring and kept at 70°C, and 0.03 part by weight of benzoyl peroxide as a thermal polymerization initiator dissolved in 1 part by weight of ethyl acetate was dropped from the dropping funnel. Solution. After starting the reaction, the reaction was carried out at the temperature in this state for 10 hours to obtain an acrylic copolymer solution.

Next, on one side of the polyester film, the above-mentioned acrylic copolymer solution was applied by a die coating method to provide an adhesive layer with a thickness of 8 μm.

2. Black ink layer

To the carbon black (CB-1) used in CB masterbatch 1 (CB-MB1), add a commercially available ink medium (polyurethane series/vinyl chloride-vinyl acetate copolymer) and a solvent (ketone/aromatic hydrocarbon). /Alcohol), mixed and stirred to prepare a black ink whose carbon content after solvent drying is 50% by weight.

Next, the above-mentioned black ink was used on the polyester film, and the number of times required for light-shielding properties was used to form a dried black ink layer with a thickness of 2 μm by lithography.

(Example 1)

In accordance with the composition shown in the table, blend into the polyester raw material 34 parts by mass of polyethylene terephthalate, polyethylene terephthalate-isophthalic acid (IPA) copolymer 1:26 parts by mass and 1:40 parts by mass of the CB masterbatch were vacuum dried at 180°C for 2 hours. Then, the molten sheet extruded from the T-die is melted and discharged in an extruder heated to 280°C, and the molten sheet extruded from the T-die is adhered and solidified on a casting drum whose surface temperature is maintained at 25°C by an electrostatic application method to obtain an unstretched sheet. sheet.

Next, the obtained unstretched sheet is preheated by a roller set heated to a temperature of 80°C, and then between the roller heated to a temperature of 85°C and a roller adjusted to a temperature of 25°C, the speed difference is 3 times longer. After being stretched 3 times in the side direction (longitudinal direction), it was cooled by a roller set at a temperature of 25° C. to obtain a uniaxially stretched sheet. In addition, while holding the two ends of the obtained uniaxially stretched sheet with clamps, it is guided to the 80°C temperature preheating zone in the tenter, and then continuously in the heating zone maintained at 90°C at a right angle to the longitudinal direction. Direction (width direction) extension 3.6 Times. Furthermore, next, heat treatment was performed at 230°C for 20 seconds in the heat treatment zone in the tenter, and while the relaxation treatment was performed in the width direction of 6%, the polyester film was uniformly gradually cooled. Next, the discharge amount of the extruder and the linear speed after the casting drum were adjusted so that the thickness of the polyester film after film formation became 16 μm, and the polyester film described in Example 1 was obtained. The film-forming properties were very excellent, and even if the film was continuously formed for 1 hour under the above conditions, the film did not break even once. After implementing the light-shielding evaluation and light-shrinkage evaluation of the obtained polyester film, it was found that both had very excellent light-shielding properties and light shrinkage resistance. In addition, since it is a very thin film and satisfies the above-mentioned characteristics, it is known that it is a polyester film suitable for use as a light-shielding substrate for electronic equipment.

In addition, an adhesive layer was provided on a single polyester film to produce a light-shielding tape. Since the obtained light-shielding tape has very excellent light-shielding properties, and there is no need to provide a black ink layer, it is known that it is a very excellent light-shielding tape from the viewpoint of reducing the environmental load or simplifying the manufacturing steps.

(Examples 2~7)

The polyester film was obtained in the same manner as in Example 1, except that the amount of the CB master batch 1 was adjusted so as to become the color pigment concentration described in the table, and the film forming conditions were adjusted so as to become the thickness described in the table. Regarding Examples 4 and 5, since film breakage occurred during film formation, film formation was performed at a stretch ratio lower than that of Example 1.

The properties of the obtained polyester film are as shown in the table. Although it is inferior to Example 1, it is found that it still has good properties, and it shows good properties even as a light-shielding substrate for electronic equipment.

In addition, the light-shielding tape was produced in the same manner as in Example 1. As a result, it was found that although it was inferior to Example 1, it had good characteristics as a light-shielding tape.

(Examples 8~13)

Except that the amount of polyethylene terephthalate-isophthalic acid (IPA) copolymer 1 was adjusted according to the ratio of the copolymerization components described in the table, the polyester film was obtained in the same manner as in Example 1. . In addition to Example 8, since film breakage occurred during film formation, the film was formed at a stretch ratio lower than that of Example 1. Among them, Example 13 had poor film forming properties, but it was still in a range that did not cause problems. .

The properties of the obtained polyester film are shown in the table. It is found that although it is inferior to Example 1, it still has good properties and shows good properties even as a light-shielding substrate for electronic equipment. Among them, Example 9 has the most excellent properties . In addition, although Example 12 was inferior in light shrinkage resistance, it was still in a range that did not pose a problem.

In addition, the light-shielding tape was produced in the same manner as in Example 1. As a result, it was found that it was a very excellent light-shielding tape.

(Examples 14-18)

In addition to the types and ratios of the copolymerization components described in the table, adjust the polyethylene terephthalate-naphthalene dicarboxylic acid (NDC) copolymer and polyethylene terephthalate-cyclohexane described in the preceding paragraph Except for the amounts of dimethanol (CHDM) copolymer and polybutylene terephthalate (PBT), the polyester film was obtained in the same manner as in Example 1. In addition to Example 17, since film breakage occurred during film formation, the film was formed at a stretch ratio lower than that of Example 1. Although Example 14 had poor film forming properties, it was still in a range that did not cause problems. .

The properties of the obtained polyester film are shown in the table. It is found that Example 17, which uses CHDM as the diol component of the copolymerization component and has a copolymerization component ratio of 9 mol%, is very excellent in the same way as Example 1. Shading and light shrinkage resistance. Also, about The other examples are inferior to Example 1 or 17, but still show good characteristics, and it is known that they show good characteristics even as a light-shielding tape for electronic equipment.

Furthermore, the light-shielding tape was produced in the same manner as in Example 1. As a result, it was found that it was a very excellent light-shielding tape.

(Examples 19-21)

As shown in the table, except for using the CB masterbatch 2, CB masterbatch 3, and titanium oxide masterbatch described in the previous paragraph, and changing the type and content of the coloring pigment, the polyester film was obtained in the same manner as in Example 1. . Although Example 20 had poor film forming properties, it was still in a range that did not cause problems.

The properties of the obtained polyester film are shown in the table. It is found that although Example 19 is inferior to Example 1 in light-shielding properties and light shrinkage resistance, it is still excellent. Although Example 20 has a lower color pigment concentration than Example 1, However, the same shading property as in Example 1 can be obtained. In addition, although Example 21 had poor light-shielding properties, it was still in a range that did not pose a problem.

In addition, the light-shielding tape was produced in the same manner as in Example 1. As a result, it was found that although it was inferior to Example 1, it showed good characteristics as a light-shielding tape.

(Example 22)

Except for the ratios listed in the table, the preparation components are polyethylene naphthalate described in the previous paragraph, and the dicarboxylic acid component as the copolymerization component is terephthalic acid (TPA). Except for the ethylene phthalate, the polyester film was obtained in the same manner as in Example 1. As a result, although the film forming property was poor, it was still in a range that did not cause a problem.

The properties of the obtained polyester film are shown in the table. It is inferior to Example 1, but still has excellent characteristics.

Furthermore, the light-shielding tape was produced in the same manner as in Example 1. As a result, it was found that it was a very excellent light-shielding tape.

(Example 23)

The polyester film was obtained in the same manner as in Example 1 except that the film thickness was 10 μm. The properties of the obtained film are as shown in the table. Although the light-shielding property is inferior to that of Example 1, it is still excellent.

In addition, the light-shielding tape was produced in the same manner as in Example 1. As a result, it was found that it was an excellent light-shielding tape.

(Examples 24-35)

The polyester film was obtained in the same manner as in Example 23 except that the film forming conditions were changed as described in the table. In addition, when performing longitudinal stretching in Examples 25 to 35, an infrared heater (RH) with a distance of 400 mm between the films, a heater capacity of 6.6 kW, and a heat generation length of 800 mm was installed between the preheating roller and the stretching roller. Film making. It is known that the obtained polyester film has the optical density and ten-point average roughness Rz (μm) and the film by changing the film temperature and stretching magnification during vertical stretching and the preheating temperature during horizontal stretching of the film forming conditions. The thickness (μm) ratio (Rz/T) changes. In addition, although Example 35 had poor film forming properties, it was still in a range that did not cause problems.

The properties of the obtained polyester film are as shown in the table. It is found that Examples 25, 34, and 35 have better light-shielding properties than Example 23.

Furthermore, the light-shielding tape was produced in the same manner as in Example 1. As a result, it was found that Examples 25, 34, and 35 were superior to the light-shielding tape of Example 23.

(Comparative example 1)

As shown in the table, except that the homopolymer of polyethylene terephthalate was used alone, it was the same as in Example 1. Although the light shielding property and the light shrinkage resistance were very excellent, the film forming properties were poor.

(Comparative example 2)

As shown in the table, except that the polyethylene terephthalate-isophthalic acid (IPA) copolymer 2 is used alone, the rest is the same as in Example 1. Although it has very good light-shielding properties and good film forming properties, The light resistance is poor.

(Comparative example 3)

As shown in the table, it is the same as Example 12 except that the color pigment is increased in concentration. Although it is excellent in light-shielding properties, the film-forming properties and light shrinkage resistance are inferior.

(Comparative Example 4)

As shown in the table, it is the same as Example 1 except that the color pigment is reduced in concentration. Although the film-forming properties and light shrinkage resistance are very excellent, the light shielding properties are poor.

(Industrial availability)

The polyester film of the present invention is a film, and has excellent hiding and film forming properties, and excellent shrinkage when exposed to light. Of course, it is suitable for light-shielding substrates used in electronic equipment, and can also be applied For example: industrial materials such as cover film, solar battery backsheet film, motor insulating film; lithium-ion battery exterior film, design film, protective film and other packaging materials; ribbon film, building material film, thermal Various applications such as sensitive transfer film.

Claims (8)

A polyester film with a ratio of optical density to thickness (μm) (optical density (OD)/thickness (T)) of 0.22 or more and 2.0 or less. In differential scanning calorimetry (DSC), after keeping it in the molten state for 5 minutes , When cooling at a cooling rate of 10°C/min, the cooling crystallization temperature Tmc is above 180°C and below 210°C. The polyester film of claim 1, wherein the black pigment contains 3.5% by mass or more and 30% by mass or less. Such as the polyester film of claim 1 or 2, wherein the ten-point average roughness Rz (μm) of at least one surface satisfies the ratio of Rz (μm) to thickness (μm) (ten-point average roughness (Rz)/thickness (T)) is below 0.30. The polyester film of claim 1 or 2, wherein the polyester resin constituting the film contains a phthalic acid component and/or a cyclohexane dimethanol component as the polyester constituent components. The polyester film of claim 4, wherein the polyester constituting the film contains 0.5 mol% or more and 20 mol% or less of isophthalic acid relative to the total dicarboxylic acid component, or contains cyclohexane relative to the total glycol component The dimethanol component is 0.5 mol% or more and 20 mol% or less. Such as the polyester film of claim 1 or 2, wherein the film thickness is 28 μm or less. Such as the polyester film of claim 1 or 2, which is used as a light-shielding substrate of electronic equipment. A light-shielding tape that uses the polyester film of any one of claims 1 to 6.