JP2010046899A - Heat-resistant composite film and substrate film for flexible electronics device composed of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-resistant composite film which has superior heat-resistant dimension stability because both of temperature expansion coefficient and heat shrinkage rate in a high-temperature region are small, and is excellent in film surface flatness and interlayer adhesiveness, with a convenient method. <P>SOLUTION: The heat-resistant composite film is a composite film having a layer configuration obtained by laminating biaxially oriented polyester films on both surfaces of a heat-resistant insulation paper. The laminated biaxially oriented polyester film comprises a polyester base layer having a copolymerization amount of ≥0 mol% to ≤5 mol% and a copolymerization polyester layer having a copolymerization amount of ≥11 mol% to ≤30 mol%, the laminated biaxially oriented polyester film is laminated on the heat-resistant insulation paper via the copolymerization polyester layer and the outermost layer of the composite film is the polyester base layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heat-resistant composite film excellent in heat-resistant dimensional stability and surface flatness and a substrate film for a flexible electronic device comprising the same, and more specifically, both a thermal expansion coefficient and a thermal contraction rate in a high temperature range are small. In addition, the present invention relates to a heat-resistant composite film excellent in surface flatness and interlayer adhesion, and a substrate film for flexible electronic devices such as organic EL, electronic paper, and solar cells.

  Polyester films, especially biaxially stretched films of polyethylene terephthalate and polyethylene naphthalate, have excellent mechanical properties, heat resistance, and chemical resistance. Therefore, magnetic tape, ferromagnetic thin film tape, photographic film, packaging film, electronic parts It is widely used as a material such as a film for electrical use, an electrical insulation film, a film for metal lamination, a film attached to the surface of a glass display, and a protective film for various members.

  Conventionally, a glass substrate has been used for an image display device represented by a liquid crystal display. In recent years, however, image display devices have been studied from heavy and fragile glass substrates to highly transparent polymer film substrates because of demands for thinness, weight reduction, large screen, freedom of shape, and curved surface display. . In particular, in recent years, development of self-luminous elements typified by organic EL has progressed, and an image display apparatus that needs to use many members because it has to adopt a backlight like a liquid crystal display is going to change. Even in such applications, demands for improving the ease of breaking and weight, which are one of the drawbacks of glass, are increasing year by year.

  Various polymer materials have been studied as highly transparent polymer film substrates, and a polyethylene naphthalate film has been studied as one of materials having higher heat-resistant dimensional stability, for example, as disclosed in Patent Document 1. On the other hand, particularly in the flexible electronics field, dimensional stability against temperature change is required. For example, in Patent Document 2, the temperature expansion coefficient (αt) at 30 to 100 ° C. is 15 ppm / both in the longitudinal direction and the width direction of the film. Biaxially oriented polyester films having a temperature of 0 ° C. or less have been proposed. However, in the flexible electronics field, in recent years, a substrate film having a small dimensional change has been demanded even in a higher temperature range of 100 to 180 ° C. as in the temperature range of 100 ° C. or less.

  As an example of a biaxially oriented polyester film excellent in heat-resistant dimensional stability from room temperature to a higher temperature range from 175 ° C., for example, it is composed of at least three layers in Patent Document 3 and contains 10 to 70% by weight of a liquid crystalline resin in the core layer A laminated film has been proposed. On the other hand, since this patent document matches the thermal expansion coefficient with, for example, copper as a flexible printed circuit board, the thermal expansion coefficient of the film from room temperature to 175 ° C. specifically disclosed is about 20 ppm.

  On the other hand, when various functional layers are processed at a high temperature on a substrate film using a polymer material in the field of flexible electronics devices and the like, it may be processed at around 180 ° C., but in such a temperature range, the polymer substrate The film is required to have a low coefficient of thermal expansion of around 5 ppm and a low thermal shrinkage rate of around 0%, which are the same as those of a glass substrate, and to produce a substrate film having such characteristics in a simplified process. Is required. In addition, the surface of the substrate film is required to be flat in order to enhance the functionality of the laminated various functional layers, but it still has heat-resistant dimensional stability with a temperature expansion coefficient of about ppm and is flat. The present condition is that the film which is excellent in the property is not obtained.

JP 2004-9362 A International Publication No. 2005/110718 Pamphlet JP 2005-335347 A

  The object of the present invention is to eliminate such problems of the prior art, have both a small coefficient of thermal expansion and a high thermal contraction rate in a high temperature range, have excellent heat-resistant dimensional stability, and have surface flatness and interlayer adhesion. The object is to provide an excellent heat-resistant composite film by a simple method.

  Another object of the present invention is to provide a heat-resistant composite film that is excellent as a substrate for flexible electronics devices having excellent heat-resistant dimensional stability in a high temperature range, excellent surface flatness, and interlayer adhesion. .

  As a result of intensive studies to solve the above problems, the present inventors have a tendency that the biaxially oriented polyester film expands in the positive direction in the plane direction as the temperature rises. There is a limit to setting the temperature expansion coefficient (αt) at 100 to 180 ° C. to several ppm, while heat-resistant insulating paper typified by aramid paper tends to shrink in the surface direction as the temperature rises. Based on the knowledge, a biaxially oriented polyester film and a heat-resistant insulating paper are laminated via a copolymerized polyester layer, and the temperature expansion coefficient (αt) at 100 to 180 ° C. is close to the temperature expansion coefficient of the glass substrate −5 The present inventors have found that a heat-resistant composite film that is in the range of ˜15 ppm and has an excellent heat shrinkage rate at a high temperature of about 200 ° C. can be obtained. In addition, by making the outermost layer of the composite film a biaxially oriented polyester film, film surface flatness can also be imparted, and in order to easily bond such heterogeneous materials to each other, a polyester layer having a large amount of copolymerization is used. The inventors have found that the problem can be solved by laminating both layers, and have completed the present invention.

  That is, according to the present invention, an object of the present invention is a composite film having a layer structure in which a laminated biaxially oriented polyester film is laminated on both surfaces of a heat-resistant insulating paper, and the laminated biaxially oriented polyester film has a copolymerization amount of 0. % To 5 mol% of a polyester base layer and a copolymerized polyester layer having a copolymerization amount of 11% to 30 mol%, and the laminated biaxially oriented polyester film is formed on the heat-resistant insulating paper through the copolymerized polyester layer. Laminated, the outermost layer of the composite film is achieved by a heat resistant composite film which is a polyester base layer.

  Moreover, as for the heat resistant composite film of the present invention, as a preferred embodiment, the film has a temperature expansion coefficient (αt) at 100 to 180 ° C. in the range of −5 ppm / ° C. to 15 ppm / ° C. in both the longitudinal direction and the width direction of the film. That the film has a thermal shrinkage rate at 200 ° C. for 10 minutes of not less than −0.2% and not more than 0.2% in both the longitudinal direction and the width direction of the film, and the heat-resistant insulating paper is aramid paper. The main constituent component of the polyester constituting the polyester base layer of the laminated biaxially oriented polyester film is ethylene terephthalate or ethylene naphthalene dicarboxylate, and the main constituent of the polyester constituting the copolymerized polyester layer of the laminated biaxially oriented polyester film Component is ethylene terephthalate or ethylene It is naphthalate, the thickness per layer of the heat-resistant insulating paper is 20 μm or more and 200 μm or less, the thickness per layer of the polyester base material layer is 6 μm or more and 250 μm or less, and the thickness of each layer of the polyester base material layer The ratio of the total thickness of each layer of the heat-resistant insulating paper to the total is at least one of 0.25 and 4 inclusive.

  Moreover, this invention includes the board | substrate film for flexible electronics devices which consists of said heat resistant composite film, and at least 1 sort (s) chosen from the group which consists of organic EL, electronic paper, and a solar cell is illustrated as a flexible electronics device. Is done.

  Since the heat-resistant composite film of the present invention has both a low coefficient of thermal expansion and a high thermal contraction rate in a high temperature range and excellent film surface flatness, flexible electronic devices such as organic EL, electronic paper, and solar cells. It can be suitably used as a substrate film.

The present invention will be described in detail below.
<Laminated biaxially oriented polyester film>
The laminated biaxially oriented polyester film of the present invention is a laminate of at least two layers having a polyester base layer having a copolymerization amount of 0% to 5 mol% and a copolymer polyester layer having a copolymerization amount of 11% to 30 mol%. It is a film.
The upper limit of the number of laminated biaxially oriented polyester films is preferably 5 layers or less, more preferably 2 layers of a copolymerized polyester layer and a polyester base layer.
The copolymerized polyester layer and the polyester base material layer constituting the laminated biaxially oriented polyester film are preferably films that are melt-laminated in a film forming process using a coextrusion method.

  The polyester film needs to be biaxially oriented from the viewpoint of heat-resistant dimensional stability such as temperature expansion coefficient and thermal shrinkage. In the case of an unstretched or uniaxial polyester film, even if it is bonded to a heat-resistant insulating paper with high dimensional stability, the composite film achieves the scope of the present invention in terms of the coefficient of thermal expansion and heat shrinkage characteristics in the unstretched direction. I can't.

<Polyester substrate layer>
In the laminated biaxially oriented polyester film of the present invention, the polyester constituting the polyester base layer is a linear saturated polyester synthesized from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. The polyester has a copolymerization amount of 0% or more and 5 mol% or less based on the total acid component or total diol component of the polyester base layer.

Specific examples of the polyester include polyethylene terephthalate, polyethylene isophthalate, polyethylene isophthalate, polybutylene terephthalate, poly (1,4-cyclohexylenedimethylene terephthalate), and polyethylene naphthalene dicarboxylate.
Among these polyesters, polyethylene terephthalate and polyethylene naphthalene dicarboxylate are preferable because they have a good balance of thermal characteristics, mechanical properties, optical properties, and the like. In particular, polyethylene naphthalene dicarboxylate is superior to polyethylene terephthalate in terms of thermal expansion coefficient and thermal shrinkage at high temperatures and mechanical strength. The polyethylene naphthalene dicarboxylate is particularly preferably polyethylene-2,6-naphthalene dicarboxylate.

  Examples of copolymer components include oxalic acid, adipic acid, phthalic acid, sebacic acid, dodecanedicarboxylic acid, isophthalic acid, terephthalic acid, 1,4-cyclohexanedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, phenylindanedicarboxylic acid, Dicarboxylic acid components such as 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, tetralin dicarboxylic acid, decalin dicarboxylic acid, diphenyl ether dicarboxylic acid, etc., and oxycarboxylics such as p-oxybenzoic acid and p-oxyethoxybenzoic acid Acid or propylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, cyclohexane methylene glycol, neopentyl glycol, ethylene oxide adduct of bisphenol sulfone, vinyl Ethylene oxide adducts of phenol A, diethylene glycol, are preferably used such diol component polyethylene oxide glycol. These copolymerization components can be used alone or in combination of two or more.

  In these copolymer components, preferred examples of the acid component include isophthalic acid, terephthalic acid, 4,4′-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, and p-oxybenzoic acid. Examples of the diol component include trimethylene glycol, hexamethylene glycol, neopentyl glycol, and ethylene oxide adducts of bisphenol sulfone.

When the polyester constituting the polyester base layer is a copolymer, the raw material for producing the film may be either a copolymer or a polymer blend. For example, homopolyethylene-2,6-naphthalene dicarboxylate and other polyesters other than that may be prepared, and these may be transesterified during melt kneading.
The polyester may be one in which a part or all of the terminal hydroxyl group and / or carboxyl group is blocked with a monofunctional compound such as benzoic acid or methoxypolyalkylene glycol. It may be copolymerized with a trifunctional or higher functional ester-forming compound such as erythritol within a range where a substantially linear polymer is obtained.

  The polyester of the present invention is a conventionally known method, for example, a method of directly obtaining a low polymerization degree polyester by reaction of a dicarboxylic acid and a diol, or a lower alkyl ester of a dicarboxylic acid and a diol are conventionally known transesterification catalysts, such as sodium It can be obtained by performing a polymerization reaction in the presence of a polymerization catalyst after reacting with one or more of compounds containing potassium, magnesium, calcium, zinc, strontium, titanium, zirconium, manganese, and cobalt. it can. As a polymerization catalyst, antimony compounds such as antimony trioxide and antimony pentoxide, germanium compounds represented by germanium dioxide, tetraethyl titanate, tetrapropyl titanate, tetraphenyl titanate or a partial hydrolyzate thereof, titanyl ammonium oxalate , Titanium compounds such as potassium titanyl oxalate and titanium trisacetylacetonate can be used.

  When polymerization is performed via a transesterification reaction, a phosphorus compound such as trimethyl phosphate, triethyl phosphate, tri-n-butyl phosphate, or normal phosphoric acid is usually added for the purpose of deactivating the transesterification catalyst before the polymerization reaction. In view of thermal stability of the polyester, the content of the phosphorus element in the polyester is preferably 20 to 100 ppm by weight.

The polyester may be converted into chips after melt polymerization, and further subjected to solid phase polymerization under heating under reduced pressure or in an inert gas stream such as nitrogen.
The intrinsic viscosity of the polyester is preferably 0.40 dl / g or more, and more preferably 0.40 to 0.90 dl / g. If the intrinsic viscosity is less than 0.40 dl / g, process cutting may occur frequently. On the other hand, if it is higher than 0.9 dl / g, melt extrusion is difficult because of high melt viscosity, and the polymerization time is long and uneconomical.

The polyester base layer may contain a colorant, an antistatic agent, and an antioxidant within a range that does not impair the function of the present invention.
The polyester base layer preferably does not contain a lubricant or contains a small particle size lubricant which does not affect the properties even if contained. When it contains a lubricant, it is preferably contained in the range of 5% by weight or less, more preferably 1% by weight or less, based on the weight of the polyester base layer. The average particle size of the lubricant is not particularly limited, but is preferably 0.001 to 5 μm. Here, the average particle diameter means an average value of the particle diameters of all particles measured by an electron micrograph or a transmission electron micrograph of the particles. The type of lubricant is not particularly specified, and examples thereof include calcium carbonate, calcium oxide, aluminum oxide, kaolin, silica, crosslinked acrylic resin particles, crosslinked polystyrene resin particles, melamine resin particles, and crosslinked silicone resin particles.

  The thickness per layer of the polyester base material layer is preferably 6 μm or more and 250 μm or less, more preferably 12 μm or more and 200 μm or less, and particularly preferably 25 μm or more and 125 μm or less. When the thickness per layer of the polyester base layer is less than the lower limit, the ratio of the biaxially oriented polyester film in the composite film is small, the temperature expansion coefficient in the surface direction is increased in the negative direction, and the temperature expansion of the composite film The lower limit of the coefficient may not be reached. In addition, when the thickness per layer of the polyester base layer exceeds the upper limit, the ratio of the biaxially oriented polyester film in the composite film increases and the temperature expansion coefficient in the plane direction increases in the positive direction, and the temperature expansion of the composite film May exceed the upper limit of the coefficient. In addition, when the thickness per one layer of the polyester base material layer exceeds the upper limit, when used as a substrate film of a flexible electronic device, free flexibility may not be obtained.

<Copolymerized polyester layer>
The composite film of the present invention is laminated with a heat-resistant insulating paper through a copolymerized polyester layer of a laminated biaxially oriented polyester film, and the copolymerized polyester layer is a copolymerized polyester layer having a copolymerization amount of 11% or more and 30 mol% or less. It is.
When the copolyester layer is not provided, since the adhesive force between the heat-resistant insulating paper and the polyester base layer is not sufficient, the temperature expansion coefficient of the composite film at 100 to 180 ° C. is out of the scope of the present invention.

  The copolymerized polyester layer of the present invention can be used to produce a laminated film by coextrusion with a polyester base layer, so that it is troublesome to apply an adhesive when bonding dissimilar materials such as polyester film and heat-resistant insulating paper. Adhesiveness can be easily increased by merely thermocompression bonding through the copolymerized polyester layer without passing through a simple process.

  Specifically, the polyester constituting the copolyester layer is mainly composed of ethylene terephthalate or ethylene naphthalate, and the component is 70 to 89 mol% based on the total acid component of the polyester constituting the copolyester layer. It is. When the main component amount is less than the lower limit, the film forming property in the stretching process is lowered, the composition with the polyester base material layer is greatly different, and the adhesion between the layers is lowered. On the other hand, when the main component amount exceeds the upper limit, the difference in melting point with the polyester base material layer becomes small, and adhesion with the heat-resistant insulating paper becomes difficult. In addition, the main constituent component of the copolyester is the same as the main constituent component of the polyester base layer, or a lower melting point than the polyester base layer when the two layers are compared as the melting point of the homopolymer It is an ingredient.

In such a copolymer polyester, the raw material at the time of film production may be in the form of a copolymer or a polymer blend. For example, homopolyethylene-2,6-naphthalene dicarboxylate and other polyesters other than that may be prepared, and these may be transesterified during melt kneading.
Copolymerization components other than the main components include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid; adipic acid, azelaic acid, sebacic acid, decanedicarboxylic acid An aliphatic dicarboxylic acid such as cycloaliphatic dicarboxylic acid, an acid component such as cyclohexanedicarboxylic acid, an aliphatic diol such as butanediol or hexanediol, or a glycol component such as cycloaliphatic diol such as cycloaliphatic diol. Preferable examples can be given. Among these, terephthalic acid, naphthalenedicarboxylic acid, or isophthalic acid is preferred because it tends to lower the melting point while maintaining stretchability.
Further, the subordinate polymer can be selected from the polymer group exemplified as the main constituent component.

  The amount of copolymerization is 11% or more and 30 mol% or less based on the total acid component or total diol component of the copolymerized polyester layer. When the amount of copolymerization is less than the lower limit, the difference in melting point with the polyester base layer becomes small and adhesion with the heat-resistant insulating paper becomes difficult. On the other hand, when the upper limit is exceeded, the film-forming property in the stretching process decreases. However, the composition of the polyester base layer is greatly different, and the adhesion between the layers is lowered.

Although the thickness of a copolyester layer is not specifically limited, Preferably it is the range of 5-50 micrometers, More preferably, it is 5-30 micrometers, More preferably, it is 5-20 micrometers, Most preferably, it is 5-10 micrometers.
The polyester constituting the copolymerized polyester layer can be produced in the same manner as the polyester of the polyester base layer. Moreover, the copolyester layer may contain a lubricant, a colorant, an antistatic agent and an antioxidant within the range not impairing the function of the present invention.

<Heat resistant insulation paper>
The heat-resistant insulating paper of the present invention is a heat-resistant inorganic or organic fiber cloth, specifically, a glass fiber cloth, an aramid fiber cloth, a polybenzazole fiber cloth, and a carbon fiber cloth. At least one selected from the above is preferable, and among these, an aramid fiber cloth and a polybenzazole fiber cloth are more preferable.
The glass-based fiber cloth is also called a glass cloth, and examples thereof include E glass (non-alkali glass), S glass, D glass, quartz, and high dielectric constant glass. The aramid fiber cloth is also referred to as aramid paper, and is produced by making aramid fibers with a binder as necessary and then applying temperature and pressure. In addition, as aramid, poly- typified by Kevlar (trade name: manufactured by DuPont Toray Kevlar), Technora (trade name: manufactured by Teijin Techno Products), and Conex (product name: manufactured by Teijin Techno Products) Examples include copolymers of p-phenylene phthalamide, poly-m-phenylene phthalamide, p-phenylene phthalamide, and 3,4'-diphenyl ether phthalamide. Examples of the carbon fiber cloth include carbon fiber and silicon carbide fiber.
Among these, aramid paper is preferable, and an aramid paper using poly-p-phenylenephthalamide, which is usually also referred to as para-aramid, is particularly preferable from the viewpoint of heat resistance.

  The weaving method of the woven filaments of the fiber cloth constituting the heat-resistant insulating paper is not particularly limited, and may be a woven fabric having a structure such as plain weave, nanako weave, satin weave, twill weave, and preferably plain weave. Moreover, it is not limited to a woven fabric and may be a non-woven fabric. The thickness per layer of the heat-resistant insulating paper is preferably 20 μm or more and 200 μm or less, more preferably 40 μm or more and 120 μm or less. If the thickness per layer of heat-resistant insulating paper is less than the lower limit, the proportion of heat-resistant insulating paper in the composite film is small, the temperature expansion coefficient in the surface direction is increased in the positive direction, and the upper limit of the temperature expansion coefficient of the composite film May be exceeded. Also, if the thickness per layer of heat-resistant insulating paper exceeds the upper limit, the proportion of heat-resistant insulating paper in the composite film will increase and the temperature expansion coefficient in the surface direction will increase in the negative direction, and the lower limit of the temperature expansion coefficient of the composite film May be less than

<Layer structure>
The composite film of the present invention has a layer structure in which a laminated biaxially oriented polyester film is laminated on both sides of a heat resistant insulating paper (A), and the laminated biaxially oriented polyester film is heat resistant via a copolymerized polyester layer (B). It is laminated | stacked on the insulating paper and the outermost layer of this composite film needs to be a polyester base material layer (C).

That is, in the composite film of the present invention, at least the polyester base layer (C) / copolymerized polyester layer (B) / heat-resistant insulating paper (A) / copolymerized polyester layer (B) / polyester base layer (C) are sequentially laminated. 5 layers as a basic structure, and the layer structure of (B) / (A) / (B) / (C) as one unit on one or both sides of the polyester base layer having such a five-layer structure. Preferred examples include a 9-layer configuration, a 13-layer configuration, and a 17-configuration in which one or more units are stacked. The composite film of the present invention is particularly preferably (C) / (B) / (A) / (B) / (C) 5 in which an adhesive layer and a biaxially oriented polyester film are sequentially laminated on both surfaces of a heat-resistant insulating paper. It is a layer structure.
In addition, when the laminated biaxially oriented polyester film includes a layer other than the copolymerized polyester layer and the polyester base material layer, another layer can be further included between the above layer configurations.

  The composite film of the present invention uses a sheet-like heat-resistant insulating paper having a negative temperature expansion coefficient in the plane direction as a core layer, and is laminated with a biaxially oriented polyester film having a positive temperature expansion coefficient in the plane direction. Thus, the negative direction thermal expansion coefficient and the positive direction thermal expansion coefficient are offset in the plane direction of both layers, and the composite film is for a conventional substrate of −5 to 15 ppm / ° C. in a high temperature range of 100 to 180 ° C. It is possible to achieve a temperature expansion coefficient in a region not obtained with a polymer film. In a high temperature range of 100 to 180 ° C., a temperature expansion coefficient close to that of a glass substrate of −5 to 15 ppm / ° C. is a region that cannot be normally achieved with a biaxially oriented polyester film alone, while an inorganic system having high heat resistance or An organic material is a material that is poor in processability and difficult to form into a thin film, and is therefore achieved by using a sheet-like heat-resistant insulating paper composed of a fiber cloth as in the present invention. Also, by using a biaxially oriented polyester film polyester base layer as the outermost layer, the surface roughness of the sheet-like heat-resistant insulating paper composed of fiber cloth is concealed, and the surface flatness required for the substrate film of flexible electronics devices Can also be provided.

<Temperature expansion coefficient (αt)>
The composite film of the present invention preferably has a temperature expansion coefficient (αt) at 100 to 180 ° C. in the range of −5 ppm / ° C. to 15 ppm / ° C. in both the longitudinal direction and the width direction of the film. In addition, the longitudinal direction of a film may be called a film continuous film forming direction, a vertical direction, or MD direction. Moreover, the width direction of a film is a direction orthogonal to the longitudinal direction of a film, and may be called a horizontal direction or a TD direction. The lower limit of the temperature expansion coefficient (αt) in both directions at 100 to 180 ° C. of the composite film is more preferably −3 ppm / ° C., particularly preferably 2 ppm / ° C. Moreover, the upper limit of the temperature expansion coefficient (αt) in both directions at 100 to 180 ° C. of the composite film is more preferably 10 ppm / ° C., particularly preferably 7 ppm / ° C. When the temperature expansion coefficient (αt) is less than the lower limit, the dimensional change becomes too large in the minus direction in the surface direction due to the temperature change. For example, when used as a substrate film of a flexible display, a gas barrier laminated on the substrate film Differences in temperature expansion coefficient from layers, electrode layers, etc. may occur, defects in the functional layer may occur during high temperature processing, and pattern alignment may be misaligned, leading to performance degradation. On the other hand, when the temperature expansion coefficient (αt) exceeds the upper limit, the dimensional change becomes too large in the plane direction due to the temperature change. For example, when it is used as a substrate film of a flexible display, it is laminated on the substrate film. A difference in temperature expansion coefficient from a gas barrier layer, an electrode layer, or the like occurs, and defects may occur in the functional layer during high-temperature processing, and pattern misalignment may occur, leading to performance degradation.

The temperature expansion coefficient of the present invention is determined by using a TMA apparatus, pre-treating under a temperature condition of 180 ° C. for 30 minutes under a load of 40 mN with a distance between chucks of 20 mm, and then lowering the temperature to room temperature. The temperature is raised to 180 ° C. at a rate of temperature rise of 5 ° C./min, the dimensional change in the longitudinal direction and the width direction of the film is measured, and the dimensional change rate calculated by the following formula (1) is obtained.
[alpha] t = _{{[(L 2 -L 1) × 10} 6 ] _{/ (L 1 × ΔT)}} ··· (1)
(In the above formula, L ₁ represents a sample length (mm) at 100 ° C., L ₂ represents a sample length (mm) at 180 ° C., and ΔT represents 80 (= 180 ° C.-100 ° C.) which is a measurement temperature difference. )

<Heat shrinkage>
The composite film of the present invention preferably has a thermal shrinkage rate of -0.2% or more and 0.2% or less in the longitudinal direction and the width direction when heat-treated at 200 ° C for 10 minutes. The lower limit of the heat shrinkage rate in both directions when the composite film is heat-treated at 200 ° C. for 10 minutes is more preferably −0.1%. The upper limit of the heat shrinkage rate in both directions when the composite film is heat-treated at 200 ° C. for 10 minutes is more preferably 0.1%. When such a heat shrinkage rate is less than the lower limit, the dimensional change becomes too large in the negative direction in the surface direction at high temperatures. For example, when used as a substrate film of a flexible display, a gas barrier layer and an electrode layer laminated on the substrate film The thermal contraction rate is different from the above, and defects may occur in the functional layer during high-temperature processing, and the alignment may be misaligned. On the other hand, if the thermal shrinkage rate exceeds the upper limit, the dimensional change becomes too large in the plus direction in the surface direction at high temperature, for example, a gas barrier layer laminated on the substrate film when used as a substrate film of a flexible display, A difference in thermal contraction rate from an electrode layer or the like occurs, and a defect may occur in the functional layer during high-temperature processing, or a pattern misalignment may occur, leading to performance degradation.

In addition, with the heat shrinkage rate of the present invention, the film samples are marked at intervals of 30 cm, heat-treated in an oven at 200 ° C. for 10 minutes without applying a load, and the distance between the marks after heat treatment is measured, It is the thermal shrinkage calculated by the following formula (2) in the longitudinal direction and the width direction of the film.
Thermal shrinkage rate (%) = {(distance between the pre-heat treatment gauge points−distance between the heat treatment gauge points) / distance between the heat treatment gauge points} × 100 (2)

  In order to achieve both the temperature expansion coefficient and the heat shrinkage rate of the present invention, a heat-resistant insulating paper and a polyester base material layer are laminated via a copolymerized polyester layer, and the total thickness of each layer of the biaxially oriented polyester film This is achieved when the ratio of the total thickness of the heat-resistant insulating paper to the film, the film stretching ratio, and the heat setting temperature are within the ranges described below.

<Film thickness>
The total thickness of the composite film of the present invention is preferably 42 μm or more and 1350 μm or less. The lower limit of the total thickness of the composite film is more preferably 50 μm, and particularly preferably 100 μm. The upper limit of the total thickness of the composite film is more preferably 800 μm, still more preferably 700 μm, particularly preferably 500 μm, and most preferably 250 μm. When the total thickness of the composite film is less than the lower limit, for example, when used as a base material for a flexible display, it may not have sufficient strength as a support. Moreover, when the total thickness of a composite film exceeds an upper limit, when using as a base material of a flexible display, for example, free flexibility may not be acquired.

The thickness of each layer of the polyester base layer and the copolyester layer and the thickness of the heat-resistant insulating paper are as described above.
The ratio of the total thickness of each heat-resistant insulating paper to the total thickness of each layer of the polyester base layer is preferably 0.25 or more and 4 or less, more preferably 0.33 or more and 3 or less, particularly preferably 0. .5 or more and 2 or less. When the ratio of the total thickness of each layer of the heat-resistant insulating paper to the total thickness of each layer of the polyester base layer is less than the lower limit, the ratio of the heat-resistant insulating paper in the composite film is small, so the temperature expansion coefficient and heat shrinkage of the present invention The rate may exceed the upper limit. On the other hand, when the ratio of the total thickness of each layer of heat-resistant insulating paper to the total thickness of each layer of the polyester base layer exceeds the upper limit, the proportion of the heat-resistant insulating paper in the composite film becomes too large, so the temperature expansion coefficient of the present invention In addition, the thermal shrinkage rate may be less than the lower limit.

<Surface flatness>
The heat-resistant composite film of the present invention has a layer structure of at least five layers in which a polyester base material layer is laminated on both sides of a heat-resistant insulating paper via a copolymer polyester layer, and the outermost layer of the composite film is a polyester base material. By being a layer, it has surface flatness required for a substrate film of a flexible electronic device.
The surface flatness in the present invention preferably has a center plane average roughness (WRa) of 0.1 nm or more and 20 nm or less. The center surface average roughness (WRa) is a measurement magnification of 25 times using a non-contact type three-dimensional roughness meter (NT-2000) manufactured by WYKO, and a measurement area of 246.6 μm × 187.5 μm (0.0462 mm ² ). Under the condition, it is obtained from the following equation by the surface analysis software built in the roughness meter.

（上式中、Ｚ_ｊｋは測定方向（２４６．６μｍ）、それと直交する方向（１８７．５μｍ）をそれぞれｍ分割、ｎ分割したときの各方向のｊ番目、ｋ番目の位置における三次元粗さチャート上の高さである。）

(In the above formula, Z _jk is the three-dimensional roughness at the j-th and k-th positions in each direction when the measurement direction (246.6 μm) and the direction orthogonal to it (187.5 μm) are divided into m and n, respectively. (Height on the chart.)

  When the center plane average roughness (WRa) of the outermost layer of the composite film is less than the lower limit, the slipperiness of the film during processing may be poor, and workability may be reduced. When the center plane average roughness (WRa) of the outermost layer of the composite film exceeds the upper limit, when a functional layer such as a gas barrier layer or an electrode layer is laminated, a fine gap is generated between the composite film and the functional layer. Performance may not be sufficiently exerted or the surface properties of the functional layer may be affected. In order to achieve such a range of the center plane average roughness (WRa), the outermost layer of the composite film needs to be a polyester base layer, and preferably does not contain a lubricant in the polyester base layer. If it is contained, it is preferably contained in the range of 5% by weight or less, more preferably 1% by weight or less, based on the weight of the polyester base layer.

<Application>
The heat resistant composite film of the present invention has a temperature expansion coefficient of -5 to 15 ppm / ° C. at a high temperature range of 100 to 180 ° C., which is very close to 0, and at the same time, heat shrinkage at a high temperature of about 200 ° C. Since a heat-resistant film having a very excellent rate can be obtained, it is suitable for a substrate film of a flexible electronic device including a heating process at around 180 ° C. Examples of the flexible electronic device include organic EL, electronic paper, solar cell, reflective liquid crystal, organic TFT, flexible printed circuit and the like. Among these, at least selected from the group consisting of organic EL, electronic paper, and solar cell. One type is preferably exemplified.

  When used as a substrate film for flexible electronic devices, the composite film of the present invention has precise heat-resistant dimensional stability, so the thermal expansion coefficient and thermal contraction rate of functional layers such as gas barrier layers and electrode layers are close, and high-temperature processing is possible. In some cases, the functional layer is not cracked or cracked, the effect of reducing the performance degradation is obtained, and an excellent resolution without pattern misalignment is obtained.

<Manufacturing method>
The composite film of the present invention can be produced by the following method.
A laminated biaxially oriented polyester film including a polyester base layer and a copolyester layer can be produced, for example, using a coextrusion method. The biaxially oriented polyester film having two layers, that is, a polyester base layer and a copolyester layer will be specifically described. After drying the polyester chip constituting the polyester base layer and the polyester chip constituting the copolymer polyester layer, each is supplied to each extruder hopper, laminated in a two-layer feed block, and extruded onto a rotating cooling drum through a die. And solidify by cooling to obtain an unstretched film. Subsequently, the unstretched film was stretched in the biaxial direction at a magnification of 2.0 to 5.0 times in the machine direction and transverse direction at Tg to (Tg + 60) ° C., and (Tm-100) to (Tm-5) ° C. A desired film can be obtained by heat setting at a temperature for 1 to 100 seconds. Here, Tg represents the glass transition temperature of the polyester constituting the polyester base layer, and Tm represents the melting point of the polyester constituting the polyester base layer.

Stretching can be performed by a generally used method, for example, a method using a roll or a method using a stenter. The stretching may be performed simultaneously in the longitudinal direction and the transverse direction, or may be sequentially performed in the longitudinal direction and the transverse direction. Furthermore, when performing a relaxation | loosening process, heat processing can be performed in the temperature of (X-80)-X degreeC of a film. Here, X represents a heat setting temperature.
A heat-resistant composite film is obtained by laminating a heat-resistant insulating paper on a laminate of the polyester base layer and the copolyester layer thus obtained through a copolyester layer, and laminating with a laminator heated to 200 ° C. Can be obtained.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited only to these Examples. Each characteristic value was measured by the following method. Moreover, unless otherwise indicated, the part and% in an Example mean a weight part and weight%, respectively.

(1) Temperature expansion coefficient (αt)
The film sample was cut into a length of 30 mm and a width of 4 mm so that the measurement direction was the length direction, and TMA / 6100 manufactured by Seiko Instruments Inc. was used, and a load of 40 mN was applied at a distance of 20 mm between chucks. After pre-treatment for 30 minutes under the temperature condition of ° C., the temperature is lowered to room temperature, and then the temperature is raised from 100 ° C. to 180 ° C. at a rate of 5 ° C./min. The dimensional change rate was determined by the following formula (1).
αt = {[(L ₂ −L ₁ ) × 10 ⁶ ] / (L ₁ × ΔT)} (1)
(In the above formula, L ₁ represents a sample length (mm) at 100 ° C., L ₂ represents a sample length (mm) at 180 ° C., and ΔT represents 80 (= 180 ° C.-100 ° C.) which is a measurement temperature difference. )

(2) Heat shrinkage rate Marks are applied to film samples at intervals of 30 cm, heat treatment is carried out in an oven at 200 ° C. for 10 minutes without applying a load, the distance between the marks after heat treatment is measured, In the width direction, the thermal contraction rate was calculated by the following formula (2).
Thermal shrinkage rate (%) = {(distance between the pre-heat treatment gauge points−distance between the heat treatment gauge points) / distance between the heat treatment gauge points} × 100 (2)

(3) Film thickness The total thickness of the composite film was measured using an electronic micrometer (trade name “K-312A type” manufactured by Anritsu Corporation) at a needle pressure of 30 g. In addition, each layer thickness of the biaxially oriented polyester film, each layer thickness of the adhesive layer, and each layer thickness of the heat-resistant insulating paper is wrapped in an epoxy resin (trade name “Epomount” manufactured by Refine Tech Co., Ltd.). The embedded resin was sliced to a thickness of 50 nm using a Microtome 2050 manufactured by Reichert-Jung Co., Ltd., and measured by a transmission electron microscope (LEM-2000) at an acceleration voltage of 100 KV and 3000 times.

(4) Surface roughness Using a non-contact type three-dimensional roughness meter (NT-2000) manufactured by WYKO, with a measurement magnification of 25 times and a measurement area of 246.6 μm × 187.5 μm (0.0462 mm ² ), The center plane average roughness (WRa) is obtained from the following equation using the surface analysis software incorporated in the roughness meter. The surface roughness was measured for both outermost surfaces, and the average value of the number of measurements (n) 10 times was determined for each surface.

（上式中、Ｚ_ｊｋは測定方向（２４６．６μｍ）、それと直交する方向（１８７．５μｍ）をそれぞれｍ分割、ｎ分割したときの各方向のｊ番目、ｋ番目の位置における三次元粗さチャート上の高さである。）

(In the above formula, Z _jk is the three-dimensional roughness at the j-th and k-th positions in each direction when the measurement direction (246.6 μm) and the direction orthogonal to it (187.5 μm) are divided into m and n, respectively. (Height on the chart.)

Of the central surface average roughness (WRa) obtained for each surface, the flat surface side was evaluated according to the following criteria.
○: 0.1 nm to 20 nm (good surface flatness)
×: Over 20 nm (Poor surface flatness)

(5) Adhesion (peel strength)
About the adhesiveness through the adhesive layer of the biaxially oriented polyester film of the obtained composite film and heat-resistant insulating paper, the peel strength peeled off at a rate of 2 cm / min is measured and evaluated according to the following criteria.
○: 1.0 N / mm or more ··· Good adhesion ×: Less than 1.0 N / mm ····· Adhesion is weak

(6) Evaluation of patterning characteristics A positive photosensitive resin composition was spin-coated on a film with a spin coater (D Nippon 636, manufactured by Dainippon Screen Mfg. Co., Ltd.), pre-baked on a hot plate at 130 ° C. for 180 seconds, A coating film having a thickness of 8.0 μm was formed. The film thickness was measured with a film thickness measuring device (Lambda Ace, manufactured by Dainippon Screen Mfg. Co., Ltd.). This coating film was exposed through a reticle having a line test pattern with a width of 100 μm using a stepper having an exposure wavelength of i-line (365 nm) (Nikon Corporation, NSR2005i8A) while changing the exposure amount stepwise. Using an alkali developer (manufactured by Clariant Japan, AZ300MIF developer, 2.38 mass% tetramethylammonium hydroxide aqueous solution), the development time was adjusted so that the film thickness after development was 6.6 μm under the condition of 23 ° C. Adjustment and development were performed, followed by rinsing with pure water, followed by post-baking at 180 ° C. for 30 minutes to form a positive relief pattern. The deviation of the completed test pattern was judged according to the following criteria.
○: Pattern misalignment is 0.1% or less Good patterning characteristics ×: Pattern misalignment exceeds 0.1% Poor patterning characteristics

(Polyester 1 (PEN))
Polyethylene-2,6-naphthalenedicarboxylate (intrinsic viscosity 0.61 dl / g) was obtained by performing polycondensation reaction after transesterification using dimethyl naphthalene-2,6-dicarboxylate and ethylene glycol as monomer raw materials. . Manganese acetate tetrahydrate was used as the transesterification catalyst, and antimony trioxide was used as the polycondensation catalyst. No particles were used.

(Polyester 2 (PET))
Methyl terephthalate and ethylene glycol were used as monomer raw materials, and after ester exchange, a polycondensation reaction was performed to obtain polyethylene terephthalate (inherent viscosity 0.64 dl / g). Manganese acetate was used as the transesterification catalyst, and antimony trioxide was used as the polycondensation catalyst. No particles were used.

[Example 1]
Using the chip of composition 1 described in Table 1 as the polyester base layer and the chip of composition 3 described in Table 1 as the copolyester layer, drying at 170 ° C. for 6 hours, and then supplying each to the extruder hopper, melting temperature After melting at 305 ° C. and filtering with a stainless steel fine wire filter having an average opening of 17 μm, the layers are laminated using a two-layer feed block, extruded through a 3 mm slit die on a rotary cooling drum having a surface temperature of 60 ° C. Thus, an unstretched film was obtained. The unstretched film thus obtained was preheated at 120 ° C., and further heated by a 900 ° C. IR heater 15 mm above between low-speed and high-speed rolls and stretched 3.1 times in the longitudinal direction. Subsequently, it was supplied to a tenter and laterally at 145 ° C. 3. Stretched 3 times. The obtained biaxially oriented film was heat-fixed at a temperature of 235 ° C. for 40 seconds to obtain a biaxially oriented polyester film having a thickness of 50 μm. The obtained biaxially oriented polyester film and heat-resistant insulating paper are 100 μm thick aramid paper “Technola” (trade name) manufactured by DuPont Teijin Advanced Paper Ltd., polyester base layer / copolyester layer / heat-resistant insulating paper It was laminated in a configuration such as / copolyester layer / polyester substrate layer, and laminated with a laminator heated to 200 ° C. to obtain a heat resistant composite film. The obtained characteristics are shown in Table 2.
The laminated film of this example had high interlayer adhesion, and it was possible to obtain a film having high dimensional stability up to a high temperature range by simply laminating different materials.

[Examples 2 to 4]
Except having changed the polyester composition which comprises a polyester base material layer and a copolyester layer into the composition of Table 2, operation similar to Example 1 was performed and the composite film was obtained. Table 2 shows the characteristics of the obtained heat-resistant composite film. Each composition used a chip having a ratio of polyester 1 and polyester 2 described in Table 1.
The laminated film of each Example had high interlayer adhesion, and it was possible to obtain a film having high dimensional stability up to a high temperature range by simply laminating different materials.

[Examples 5 to 8]
A composite film was obtained in the same manner as in Example 1 except that the thickness of each layer was changed to the thickness shown in Table 2. Table 2 shows the characteristics of the obtained heat-resistant composite film.
The laminated film of each Example had high interlayer adhesion, and it was possible to obtain a film having high dimensional stability up to a high temperature range by simply laminating different materials.

[Comparative Examples 1 and 2]
Except having changed the polyester composition which comprises a polyester base material layer and a copolyester layer into the composition of Table 2, operation similar to Example 1 was performed and the composite film was obtained. The properties of the obtained composite film are shown in Table 2. Each composition used a chip having a ratio of polyester 1 and polyester 2 described in Table 1.
In the laminated film of Comparative Example 1, the copolymerized polyester layer had a small amount of copolymerization, and sufficient adhesion was not obtained at the time of laminating with heat-resistant insulating paper, so that delamination occurred. In addition, the laminated film of Comparative Example 2 could not be sufficiently formed because of the copolymerization amount of the copolymerized polyester layer and the difference in processability with the polyester base material layer.

[Comparative Example 3]
The same operation as in Example 1 was performed except that the copolyester layer was not used.
In the film of this comparative example, the polyester base material layer and the heat-resistant insulating paper were peeled off, and the film was not a laminated film.

[Comparative Example 4]
A single layer film was obtained in the same manner as in Example 1 except that only the polyester base layer was used and the copolymer polyester layer and the heat-resistant insulating paper were not used. The properties of the obtained film are shown in Table 2.
The film of this comparative example had a larger temperature expansion coefficient than the laminated film of the example.

[Comparative Example 5]
A single layer film was obtained by performing the same operation as in Example 1 except that the draw ratio and the heat setting temperature were changed only with the polyester base layer. The properties of the obtained film are shown in Table 2.
The film of this comparative example had the same thermal expansion coefficient as that of the laminated film of the example, but the thermal shrinkage rate was large.

[Comparative Example 6]
Evaluation was made only with heat-resistant insulating paper without using the polyester base material layer and the copolyester layer. Table 2 shows the characteristics of the heat-resistant insulating paper. The heat-resistant insulating paper had a large temperature expansion coefficient in the negative direction.

  Since the heat-resistant composite film of the present invention has both a low coefficient of thermal expansion and a high thermal contraction rate in a high temperature range and excellent film surface flatness, flexible electronic devices such as organic EL, electronic paper, and solar cells. It can be suitably used as a substrate film.

Claims (11)

  A composite film having a layer structure in which a laminated biaxially oriented polyester film is laminated on both sides of a heat-resistant insulating paper, wherein the laminated biaxially oriented polyester film has a copolymer base amount of 0% or more and 5 mol% or less. It has a copolymerized polyester layer with a polymerization amount of 11% or more and 30 mol% or less, and the laminated biaxially oriented polyester film is laminated on heat-resistant insulating paper via the copolymerized polyester layer, and the outermost layer of the composite film is a polyester group A heat-resistant composite film characterized by being a material layer.   2. The heat resistant composite film according to claim 1, wherein the film has a temperature expansion coefficient (αt) at 100 to 180 ° C. in a range of −5 ppm / ° C. to 15 ppm / ° C. in both the longitudinal direction and the width direction of the film.   The heat-resistant composite film according to claim 1 or 2, wherein the film has a thermal shrinkage rate at 200 ° C for 10 minutes of not less than -0.2% and not more than 0.2% in both the longitudinal direction and the width direction of the film.   The heat-resistant composite film according to any one of claims 1 to 3, wherein the heat-resistant insulating paper is aramid paper.   The heat-resistant composite film according to any one of claims 1 to 4, wherein a main constituent component of the polyester constituting the polyester base layer of the laminated biaxially oriented polyester film is ethylene terephthalate or ethylene naphthalene dicarboxylate.   The heat-resistant composite film according to any one of claims 1 to 5, wherein a main constituent component of the polyester constituting the copolymer polyester layer of the laminated biaxially oriented polyester film is ethylene terephthalate or ethylene naphthalate.   The heat-resistant composite film according to any one of claims 1 to 6, wherein the thickness per layer of the heat-resistant insulating paper is 20 µm or more and 200 µm or less.   The thickness per one layer of a polyester base material layer is 6 micrometers or more and 250 micrometers or less, The heat resistant composite film in any one of Claims 1-7.   The heat-resistant composite film according to any one of claims 1 to 8, wherein a ratio of a total thickness of each heat-resistant insulating paper to a total thickness of each polyester base material layer is 0.25 or more and 4 or less.   The board | substrate film for flexible electronic devices which consists of a heat resistant composite film in any one of Claims 1-9.   The flexible electronic device substrate film according to claim 10, wherein the flexible electronic device is at least one selected from the group consisting of organic EL, electronic paper, and solar cells.