JP5108675B2 - Composite film - Google Patents

Description

  The present invention relates to a composite film, and more particularly to a composite film suitable for a flexible electronic device substrate having excellent gas barrier properties, flexibility, heat resistance and breaking strength.

  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 recent years, development of self-luminous elements typified by organic EL has progressed in recent years, and it has been necessary to adopt a backlight like a liquid crystal display, so it is going to change for an image display device that requires many members. 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.

  Accordingly, various thermoplastic resins including polypropylene, polyethylene terephthalate, polyethylene-2,6-naphthalate, and polycarbonate have been studied as the polymer film substrate. These polymer film substrates are generally more gas or water vapor than glass substrates. Easy to penetrate. Therefore, in order to apply such a polymer film substrate to the flexible electronics field typified by organic EL, which requires a very high gas barrier property, it is considered to further stack a gas barrier layer on the substrate. . Specifically, various kinds of gas barrier layers, film thicknesses, laminated structures, and the like have been studied. For example, Patent Document 1 proposes a cured polymer layer composed of a specific silicon compound and a polyvinyl alcohol polymer, but is organic. In order to use it for an EL substrate, a higher gas barrier property is required.

  On the other hand, a technique for coating a thin glass with a resin has been studied. For example, in Patent Document 2, a flexible glass is realized by coating a thin glass with a resin mainly composed of a metal oxide polymer. . However, although excellent in barrier properties and dimensional stability, impact resistance is low, and higher durability is required for the resin coating layer.

  As described above, there is a demand for a film material having high gas barrier properties and flexibility required for flexible electronic device substrates such as organic EL, excellent impact resistance, and heat resistance that can withstand substrate processing. Is the current situation.

JP-A-10-111500 JP 2004-50565 A

  An object of the present invention is to solve the problems of the prior art, have a high gas barrier property, bendability, excellent fracture strength such as impact resistance, and heat resistance that can withstand substrate processing. The object is to provide a film suitable for a substrate.

  As a result of intensive studies to solve the above problems, the present inventors have used a polyester film and laminated it with a thin film glass, thereby having excellent gas barrier properties, flexibility, impact strength, and other fracture strength and processing heat resistance. The present inventors have found that a composite film suitable for a flexible electronic device substrate having excellent properties can be obtained, and completed the present invention.

That is, according to the present invention, an object of the present invention is to laminate an inorganic glass layer (A) having a thickness of 25 μm to 300 μm and a biaxially oriented polyester film (B) having a thickness of 5 μm to 250 μm on at least one surface thereof. Do Ri, biaxial polyester constituting the oriented polyester film (B) is polyethylene naphthalene dicarboxylate, biaxially oriented polyester film (B) longitudinal direction and the width direction of the average thermal after heat treatment at the 0.99 ° C. 30 minutes shrinkage is achieved by the composite film Ru der 0.10% to 0.05%.

The composite film of the present invention, as a preferred embodiment, it is 50% breaking energy of the double coupling film is at least 0.03 J, adhesion between the inorganic glass layer (A) and biaxially oriented polyester film (B) At least one of having a layer.

Moreover, this invention includes the board | substrate film for flexible electronic devices which consists of said composite film.
Furthermore, the present invention includes a flexible electronic device substrate including the above composite film, wherein the flexible electronic device is at least one selected from the group consisting of a flexible organic EL display, electronic paper, and a solar cell. It is included as a preferred embodiment.

  The composite film of the present invention has high gas barrier properties and flexibility that the thin glass itself has, and has high fracture strength and heat resistance that can withstand substrate processing. Therefore, organic EL, electronic paper, It can be suitably used for flexible electronic device substrates such as solar cells.

The present invention will be described in detail below.
<Inorganic glass layer (A)>
The inorganic glass layer (A) constituting the inorganic glass layer (A) of the present invention is composed of a thin film inorganic glass having a thickness of 25 μm or more and 300 μm or less. The inorganic glass layer (A) of the present invention is characterized by being very thin as compared with a normal glass plate, and can be bent while being glass and has flexibility. On the other hand, if the thickness exceeds the upper limit, the flexibility is lost. On the other hand, if the thickness is less than the lower limit, the film is too thin and the flexibility is lost, which makes it brittle.

The lower limit of the thickness of the inorganic glass layer (A) is preferably 50 μm, more preferably 75 μm, and particularly preferably 100 μm. The upper limit of the thickness of the inorganic glass layer (A) is preferably 200 μm, more preferably 150 μm, and particularly preferably 125 μm.
The kind of inorganic glass is not particularly limited, and a commonly used kind of inorganic glass can be used.

<Biaxially oriented polyester film>
The polyester constituting the biaxially oriented polyester film (B) of the present invention 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.
By using polyester as the resin constituting the resin reinforcing layer of the composite film, the strength required when used as a substrate, particularly the breaking strength against impacts, etc. can be significantly improved, while the gas barrier property is lowered. There is little generation of gas derived from it, and it does not hinder flexibility and heat resistance.

  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 preferable because it has high heat resistance, high mechanical strength, and excellent gas barrier properties.

The polyester may be a homopolymer, a copolymer obtained by copolymerizing the third component, or a blend with another resin, but a homopolymer is preferred.
When the polyester is a copolymer, 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′- Dicarboxylic acid components such as diphenyldicarboxylic acid, phenylindanedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, tetralindicarboxylic acid, decalindicarboxylic acid, diphenyletherdicarboxylic acid, p-oxybenzoic acid, p -Oxycarboxylic acids such as oxyethoxybenzoic acid, or propylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, cyclohexanemethylene glycol, neopentyl glycol, bisphenol sulfone A diol component such as ethylene oxide adduct of bisphenol A, ethylene oxide adduct of bisphenol A, diethylene glycol or polyethylene oxide glycol can be preferably used.

  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. These copolymerization components can be used alone or in combination of two or more.

  Based on the total acid component or total diol component of the polyester constituting the biaxially oriented polyester film, the main component is preferably 95 mol% or more and the copolymer component is preferably 5 mol% or less. The copolymer component is more preferably in the range of 3 mol% or less.

  When the polyester is a copolymer, the raw material at the time of film production 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 of the present invention can be obtained by a conventionally known method, for example, a method in which a polyester having a low polymerization degree is directly obtained by a reaction between a dicarboxylic acid and a diol, followed by a polymerization reaction in the presence of a polymerization catalyst. Further, as another conventionally known method, it can be obtained by a method in which a lower alkyl ester of a dicarboxylic acid and a diol are reacted using an ester exchange catalyst, and then a polymerization reaction is performed in the presence of a polymerization catalyst.
Polymerization catalysts include antimony compounds such as antimony trioxide and antimony pentoxide, germanium compounds represented by germanium dioxide, tetraethyl titanate, tetrapropyl titanate, tetraphenyl titanate or partial hydrolysates thereof, and titanyl ammonium oxalate. , Titanium compounds such as potassium titanyl oxalate and titanium trisacetylacetonate can be used.
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 the upper limit is more preferably at most 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.
Further, the intrinsic viscosity of the polyester after being formed on the biaxially oriented film is preferably 0.45 dl / g or more and 0.85 dl / g or less, and preferably 0.47 dl / g or more and 0.80 g / dl or less. Further preferred.
The intrinsic viscosity is a value (unit: dl / g) measured at 35 ° C. using o-chlorophenol as a solvent.

The biaxially oriented polyester film (B) of the present invention preferably does not contain a lubricant or has a small particle size and a small amount so as not to affect the transparency and adhesiveness problems of the present invention even if contained. .
When a lubricant is contained, it is preferably contained at 1% by weight or less based on the weight of the film (B). The average particle size of the lubricant is not particularly limited, but is preferably 0.001 to 1 μm.
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 biaxially oriented polyester film (B) of the present invention needs to be an oriented film stretched in the biaxial direction. In the case of an unstretched or uniaxial polyester film, the temperature expansion in the unstretched direction is large at the substrate processing temperature, and the bonding with the inorganic glass layer (A) is peeled off.

The thickness of the biaxially oriented polyester film (B) in the present invention is 5 μm or more and 250 μm or less. When the film thickness is within such a range, the film has the strength and flexibility necessary for use as a substrate for a flexible electronic device. When the thickness of the film (B) is less than the lower limit, sufficient strength cannot be exhibited when used for a substrate. Further, when the thickness of the film (B) exceeds the upper limit, free flexibility cannot be obtained when used for a substrate.
The thickness of the biaxially oriented polyester film (B) is preferably 12 μm or more and 500 μm or less, more preferably 25 μm or more and 350 μm or less, particularly preferably 50 μm or more and 250 μm or less, and in the range of 75 μm or more and 125 μm or less. Is most preferred.

The biaxially oriented polyester film (B) preferably has an average heat shrinkage of 0.0% or more and 1.0% or less in the longitudinal direction and width direction after heat treatment at 150 ° C. for 30 minutes, 0.01% The range is more preferably 0.60% or less and particularly preferably 0.05% or more and less than 0.10%. When the thermal contraction rate of the film (B) is within such a range, when the substrate processing is performed using the composite film, film peeling or warping due to the thermal contraction of the film is less likely to occur.
<Composite film>
The composite film of the present invention is a composite film formed by laminating an inorganic glass layer (A) and a biaxially oriented polyester film (B) on at least one surface thereof, and the thickness of the glass layer (A) is 25 μm or more and 300 μm or less. And the thickness of the film (B) is 5 μm or more and 250 μm or less.

  When the composite film has an inorganic glass layer (A), high gas barrier properties, flexibility, and heat resistance that can withstand substrate processing are expressed, and when it has a biaxially oriented polyester film (B), it is used as a substrate In addition, the strength required for heat treatment, particularly the breaking strength against impact, etc., can be greatly improved. On the other hand, there is little generation of resin-derived gas that lowers the gas barrier property, and the flexibility and heat resistance are not hindered.

  Moreover, when polyester which comprises this film (B) is a polyethylene naphthalene dicarboxylate, fracture strength improves further, on the other hand, gas barrier property and flexibility can be improved further, and processing temperature can be raised.

(destruction strength)
The 50% breaking energy of the composite film is preferably 0.03 J or more. The 50% breaking energy of the composite film is more preferably 0.04 J or more, further preferably 0.05 J or more, and particularly preferably 0.10 J or more. The upper limit of the 50% fracture energy of the composite film is not particularly limited, but is at most 0.6 J due to the characteristics of the biaxially oriented polyester film.

  When the 50% breaking energy of the composite film is less than the lower limit, sufficient strength when used as a substrate, in particular, breaking strength against impact, etc. may be exhibited, and the substrate performance may not be improved. On the other hand, the upper limit of the 50% fracture energy of the composite film is naturally determined due to the characteristics of the material constituting the composite film of the present invention.

The 50% fracture energy of the present invention is determined based on JIS standard K7211.
Such a film having 50% fracture energy can be achieved by using a biaxially oriented polyester film having a thickness of 5 μm or more and 250 μm or less as a resin layer for protecting the inorganic glass layer.

<Adhesive layer>
The composite film of the present invention preferably has an adhesive layer between the inorganic glass layer (A) and the biaxially oriented polyester film (B). By having the adhesive layer, when laminating the inorganic glass layer (A) and the biaxially oriented polyester film (B), both layers can be easily adhered, and the thin inorganic glass layer (A) in the adhesion process. Because it is difficult to apply an excessive load to the battery, it is easy to prevent destruction. Further, by having the adhesive layer, the breaking strength of the composite film can be increased.

  As a specific example of the adhesive layer, a coating layer provided by coating in the process of forming the biaxially oriented polyester film (B), an inorganic glass layer (A), and a new biaxially oriented polyester film (B) are laminated. And an adhesive layer to be inserted into.

(Coating layer)
The coating layer is preferably made of at least one water-soluble or water-dispersible polymer resin selected from polyester resins, urethane resins, acrylic resins, and vinyl resins, and particularly includes both polyester resins and acrylic resins. preferable. The polyester resin of the coating layer has a glass transition point (Tg) of 0 to 100 ° C, more preferably 10 to 90 ° C. The polyester resin is preferably water-soluble or dispersible polyester.

Such a polyester resin is composed of the following polybasic acid or its ester-forming derivative and polyol or its ester-forming derivative.
Polybasic acid components include terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, adipic acid, sebacic acid, trimellitic acid, pyromellitic acid, Examples include dimer acid and 5-sodium sulfoisophthalic acid. A copolymer polyester resin is synthesized using two or more of these acid components.

  The polyol component includes ethylene glycol, 1,4-butanediol, diethylene glycol, dipropylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, xylene glycol, dimethylolpropane, poly (ethylene oxide) glycol, poly Examples include (tetramethylene oxide) glycol, bisphenol A, ethylene oxide or propylene oxide adducts of bisphenol A, and the like. Moreover, although these monomers are mentioned, it is not limited to these.

  The acrylic resin of the coating layer used in the present invention has a glass transition point (Tg) of -50 to 50 ° C, more preferably -50 to 25 ° C. The acrylic resin is preferably water-soluble or dispersible acrylic.

  Examples of the acrylic monomer include alkyl acrylate, alkyl methacrylate (alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, 2-ethylhexyl, and cyclohexyl. Groups); hydroxy-containing monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, and 2-hydroxypropyl methacrylate; epoxy group-containing monomers such as glycidyl acrylate, glycidyl methacrylate, and allyl glycidyl ether; Acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, styrenesulfonic acid and its salts (sodium salt, potassium salt, ammonium salt, tertiary amine salt) ) Or other carboxy group or a salt thereof; acrylamide, methacrylamide, N-alkylacrylamide, N-alkylmethacrylamide, N, N-dialkylacrylamide, N, N-dialkylmethacrylate (the alkyl group is a methyl group) , Ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.), N-alkoxyacrylamide, N-alkoxymethacrylamide, N, N- Dialkoxyacrylamide, N, N-dialkoxymethacrylamide (alkoxy groups include methoxy, ethoxy, butoxy, isobutoxy, etc.), acryloylmorpholine, N-methylolacrylamide, N-methylolmethacrylamide Monomers containing amide groups such as N-phenylacrylamide and N-phenylmethacrylamide; monomers of acid anhydrides such as maleic anhydride and itaconic anhydride; vinyl isocyanate, allyl isocyanate, styrene, α-methyl styrene, vinyl methyl ether, Monomers such as vinyl ethyl ether, vinyl trialkoxysilane, alkylmaleic acid monoester, alkyl fumaric acid monoester, alkylitaconic acid monoester, acrylonitrile, methacrylonitrile, vinylidene chloride, ethylene, propylene, vinyl chloride, vinyl acetate, butadiene Is mentioned.

  The composition used in the present invention is preferably used in the form of an aqueous coating solution such as an aqueous solution, an aqueous dispersion or an emulsion to form a coating film. In order to form a coating film, if necessary, other resins than the above composition, for example, a polymer having an oxazoline group, a cross-linking agent such as melamine, epoxy, aziridine, an antistatic agent, a colorant, a surfactant. UV absorbers, lubricants (fillers, waxes) and the like can be added. In particular, the lubricity and blocking resistance can be further improved by adding a lubricant.

The solid content concentration of the aqueous coating liquid is usually 20% by weight or less, and more preferably 1% by weight or more and 10% by weight or less. If this ratio is less than the lower limit, the coating layer may not be formed uniformly. On the other hand, if the ratio exceeds the upper limit, the stability of the coating material and the coating appearance may be deteriorated.
Such a coating layer can be provided in the film-forming step of the biaxially oriented polyester film (B) as will be described later. Then, an inorganic glass layer (A) and a biaxially oriented polyester film (B) can be laminated | stacked through a coating layer, and it can be set as a composite film.

(Adhesive layer)
The adhesive layer of the present invention is not particularly limited as long as it is a layer using an adhesive having an adhesive force with glass and polyester. For example, an adhesive that is thermocompression-bonded, or an adhesive that is cured by heat or ultraviolet rays is used. The layer used is mentioned.

Examples of the curable adhesive include epoxy resin, phenol resin, acrylic resin, polyimide resin, polyamide resin, polyisocyanate resin, polyester resin, polyphenyl ether resin, and alicyclic olefin polymer. Among these, it is preferable that the adhesive layer is preferably composed of an adhesive mainly containing at least one selected from the group consisting of an acrylic resin, an epoxy resin, a polyimide resin, and a polyamide resin.
Although the thickness of an adhesive bond layer is not specifically limited, Preferably it is the range of 3 micrometers or more and 50 micrometers or less.

  When laminating the inorganic glass layer (A) and the biaxially oriented polyester film (B), the adhesive layer can be laminated via the adhesive layer to form a composite film.

<Film (B) film forming method>
The biaxially oriented polyester film of the present invention can be produced by the following method.
The biaxially oriented polyester film is obtained by, for example, melt-extruding the above polyester into a film shape and cooling and solidifying it with a casting drum to form an unstretched film. This unstretched film is stretched in the vertical and horizontal directions from Tg to (Tg + 60) ° C. A desired film can be obtained by stretching in the biaxial direction at 2.0 to 5.0 times and heat-setting at a temperature of (Tm-100) to (Tm-5) ° C. for 1 to 100 seconds. Here, Tg represents the glass transition temperature of the polyester, and Tm represents the melting point of the polyester.
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.
As a method for the relaxation treatment, it is preferable to use a method in which both edges are held by a tenter, and the clip interval is narrowed in the longitudinal direction in the oven and the rail width is narrowed in the width direction to perform the relaxation treatment. By using this method, the heat-resistant dimensional stability in the width direction can be easily controlled.
In addition, the following relaxation treatment method may be used.
i) A method in which both ends of the film are cut off in the middle of the heat setting zone until the film is wound on a roll after heat setting, and the take-up speed is reduced with respect to the film supply speed.
ii) A method of heating with an IR heater between two conveying rolls having different speeds.
iii) A method of transporting the film onto the heated transport roll and decelerating the speed of the transport roll after the heated transport roll.
iv) A method of lowering the take-up speed than the supply speed while transporting the film on a nozzle that blows hot air after heat setting.
v) A method in which the film is transported on a heated transport roll after being wound up by a film forming machine, and the speed of the transport roll is reduced.
vi) A method in which the roll speed after the heating zone is decelerated from the roll speed before the heating zone while conveying the heating zone in the heating oven or by the IR heater.

  The heat shrinkage rate of the biaxially oriented polyester film of the present invention is achieved by stretching the film at the above-mentioned draw ratio and applying a heat setting treatment, and further reducing the heat shrinkage rate by applying a relaxation treatment. .

When providing an application layer as an adhesive layer, it can be applied by the following method.
In the case of sequential stretching, the coating layer can be provided by a method in which an aqueous coating liquid is applied to a uniaxially oriented film stretched in one direction, stretched in another direction as it is, and heat-set.
As the coating method, any known coating method can be applied. For example, a roll coating method, a gravure coating method, a roll brush method, a spray coating method, an air knife coating method, an impregnation method, and a curtain coating method can be used alone or in combination. The coating amount is preferably 0.5 to 20 g, more preferably 1 to 10 g per 1 m ² of the running film. The aqueous liquid is preferably used as an aqueous dispersion or emulsion.

<Production method of composite film>
The composite film of the present invention can be produced by the following method.
The composite film can be produced by separately producing the inorganic glass layer (A) and the biaxially oriented polyester film (B) and laminating them in a further step.
When laminating both layers, it is preferable to laminate via an adhesive layer.

When laminating the biaxially oriented polyester film (B) having an application layer and the inorganic glass layer (A), both layers are laminated via the application layer, and thermocompression bonded with a heated laminator to form a laminate. The method is preferred.
In addition, using an adhesive layer, the inorganic glass layer (A) and the biaxially oriented polyester film (B) are laminated via the adhesive layer, and thermocompression bonding, thermosetting, and UV curing are performed according to the type of adhesive. To obtain a laminate.

<Application>
The composite film of this invention can be used suitably for the substrate film of a flexible electronic device. Examples of flexible electronic devices include flexible organic EL displays, electronic paper, solar cells, reflective liquid crystals, organic TFTs, flexible printed circuits, etc. Among these, the group consisting of flexible organic EL displays, electronic paper, and solar cells, among others. At least one selected from the group is preferably exemplified.

Moreover, this invention includes the board | substrate for flexible electronic devices containing the composite film of this invention.
When the composite film of the present invention is used for a substrate for a flexible electronic device, it has a high gas barrier property that cannot be obtained with a conventional resin film, and can withstand flexibility and substrate processing required for a flexible electronic device substrate. It has heat resistance and also has a breaking strength that could not be obtained with conventional composites in which glass is coated with a resin.

  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) Film thickness Film thickness was measured at 30 g of needle pressure using an electronic micrometer (trade name “K-312A type” manufactured by Anritsu Corporation).

(2) Thermal shrinkage rate Film samples were marked at intervals of 30 cm, heat-treated for 30 minutes in an oven set at 150 ° C. without applying a load, and the distance between the marks after heat treatment was measured. In each of the direction (MD direction) and the direction perpendicular to the film forming direction (TD direction), the thermal contraction rate was calculated by the following formula, and the average value thereof was obtained.
Thermal contraction rate (%) = {(distance between the pre-heat treatment gauge points−distance between the heat treatment gauge points) / distance between the heat treatment gauge points} × 100

(3) Gas barrier property Permetran W1A manufactured by MOCON was used to measure the water vapor transmission rate in an atmosphere of 40 ° C and 90 RH% and evaluated according to the following criteria.
◯: Water vapor transmission rate ≦ 0.05 g / m ² / day... Very good barrier property. X: 0.05 g / m ² / day <water vapor transmission rate.

(4) Flexibility The composite film was cut into a sheet having a length of 50 cm, the sheets were rounded so that both ends of the sheet overlapped, and judged according to the following criteria.
○: The sheet can be rolled without cracking and has sufficient flexibility. ×: The sheet is broken on the way and does not have sufficient flexibility.

(5) Heat resistance The state of the composite film when heat-treated at 150 ° C. for 30 minutes was observed according to the following criteria.
○: No peeling or warping between glass / film (good heat resistance)
×: Peeling between glass / film, warping (heat resistance failure)

(6) 50% fracture energy The 50% fracture energy E (J) of the film was measured with the apparatus of FIG. 1 and calculated based on JIS standard K7211. In FIG. 1, 1 is a weight (mass 300 g or 500 g), 2 is a U-type punch (tip diameter 4 mm, mass 142 g), 3 is a film fixing jig, and 4 is a sample film.

[Example 1]
Polyethylene-2,6-naphthalenedicarboxylate containing no particles (obtained with 0 intrinsic viscosity) obtained by conducting polycondensation reaction after transesterification using dimethyl naphthalene-2,6-dicarboxylate and ethylene glycol as monomer raw materials .61 dl / g) was used as the polyester for layer (B). Manganese acetate tetrahydrate was used as the transesterification catalyst, and antimony trioxide was used as the polycondensation catalyst.

  The obtained polyethylene-2,6-naphthalenedicarboxylate pellets were dried at 170 ° C. for 6 hours, then fed to an extruder hopper, melted at a melting temperature of 305 ° C., and a stainless steel fine wire filter having an average opening of 17 μm. The solution was filtered, extruded through a 3 mm slit die on a rotary cooling drum having a surface temperature of 60 ° C., and rapidly cooled to obtain an unstretched film. 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 stretched 3.3 times in the transverse direction at 145 ° C. The obtained biaxially oriented polyester film was heat-fixed at a temperature of 240 ° C. for 40 seconds to obtain a polyester film having a thickness of 100 μm.

  Subsequently, in a tenter type oven that can hold both edges of the film with clips, while holding both edges of the obtained film, the processing temperature is 200 ° C., the longitudinal direction (MD direction) relaxation rate is 1.0%, and the width direction. (TD direction) Relaxation treatment (sometimes referred to as annealing treatment) was performed at a relaxation rate of 1.0%.

The obtained biaxially oriented polyester film was applied to an ultra-thin glass plate having a thickness of 100 μm as an adhesive with “SK Dyne 1499M” (acrylic ester resin / ethyl acetate two-component cross-linking acrylic adhesive) ) And a curing agent “D-90” (manufactured by Soken Chemical Co., Ltd.) were mixed at a ratio of 100: 1 and bonded together using a laminator.
The properties of the obtained composite film are shown in Table 1. The composite film of this example was excellent in gas barrier properties, heat resistance, breaking strength, and flexibility.

[Examples 2 , 4, 6, 7 and Comparative Examples 5, 6 ]
The same operation as in Example 1 was carried out except that the stretching conditions, heat setting temperature, annealing treatment (relaxation treatment), polyester type and layer structure of the composite film were changed as shown in Table 1. . The properties of the obtained film are shown in Table 1. In Comparative Example 6 , polyethylene terephthalate was used instead of polyethylene-2,6-naphthalenedicarboxylate.

[Comparative Example 1]
The same operation as in Example 1 was performed except that the thickness of the biaxially oriented polyester film was changed without using the inorganic glass layer and the adhesive layer. The results are shown in Table 1.

[Comparative Example 2]
A gas barrier layer made of a SiO ₂ film having a thickness of 30 nm was formed on one side of the biaxially oriented polyester film prepared in the same manner as in Example 1 by using a sputtering method. The results are shown in Table 1.

[Comparative Example 3]
A similar gas barrier layer was also formed on the opposite surface of the film of Comparative Example 2. The results are shown in Table 1.

[Comparative Example 4]
Evaluation of a 100 μm ultrathin glass simple substance was performed. The results are shown in Table 1.

  The composite film of the present invention does not impair the high gas barrier properties and bendability of the thin film glass itself, has a higher breaking strength than the thin film glass, and has heat resistance that can withstand substrate processing. It can be suitably used for flexible electronic device substrates such as electronic paper and solar cells.

Impact resistance test equipment

Explanation of symbols

1 Weight 2 Punch 3 Film Fixing Jig 4 Sample Film

Claims (6)

Ri 25μm or 300μm of a thickness less than the inorganic glass layer (A) and biaxially oriented polyester film of the at least one surface 5μm or 250μm or less in thickness (B) the name are laminated,
The polyester constituting the biaxially oriented polyester film (B) is polyethylene naphthalene dicarboxylate,
Composite film longitudinal direction and the width direction of the average heat shrinkage, characterized in der Rukoto 0.10% to 0.05% after heat treatment for 30 minutes at 0.99 ° C. of the biaxially oriented polyester film (B). The composite film according to claim 1, wherein the composite film has a 50% breaking energy of 0.03 J or more. The composite film according to claim 1 or 2 , further comprising an adhesive layer between the inorganic glass layer (A) and the biaxially oriented polyester film (B). A composite film according to any one of claims 1 to 3 used for the flexible electronics device substrate. The flexible electronics device board | substrate containing the composite film in any one of Claims 1-4 . The flexible electronic device substrate according to claim 5 , wherein the flexible electronic device is at least one selected from the group consisting of a flexible organic EL display, electronic paper, and a solar cell.

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