JP5789938B2 - Gas barrier laminated film - Google Patents

Description

  The present invention relates to a gas barrier laminate film that is suitably used when a high gas barrier property and dimensional stability are required as a plastic substrate for a flexible FPD.

  In recent years, with the development of electronic paper and organic EL, which are expected as next-generation FPDs, in order to achieve flexibility in these FPDs, there is an increasing demand for replacing glass substrates with plastic substrates. A plastic substrate is lighter than a glass substrate and is less likely to break, and has the advantage that it can be produced on a roll-to-roll basis. However, there is a problem that the electrode pattern or the like formed on the plastic substrate is misaligned due to thermal expansion / shrinkage of the substrate due to heat treatment in the FPD manufacturing process or deformation due to moisture absorption / drying. Patent Document 1 reports that moisture absorption of a substrate can be prevented by providing a hard coat layer on a plastic substrate. In Patent Document 2, a study has been made on using a heat-resistant plastic having excellent dimensional stability for a substrate, but in order to further reduce the cost, it is necessary to ensure dimensional stability using a general-purpose plastic film.

  In order to prevent the deterioration of the internal elements of the FPD, the plastic substrate is required to have a high gas barrier property. In order to realize a plastic film having such a high gas barrier property, it is formed by a dry coating method such as a reactive vapor deposition method using electron beam vapor deposition or induction heating vapor deposition, a sputtering method, or a plasma chemical vapor deposition (CVD) method. Inorganic oxide thin films have been studied as those that can be expected to exhibit high gas barrier properties.

  However, even if the dry coating method is used, if a dense film is obtained in order to aim at high gas barrier properties, a high-temperature process is required, or the stress in the film tends to increase due to the denseness. is there. For this reason, it is difficult to obtain a dense film within the usable temperature range of the plastic film, or problems such as poor adhesion and cracking due to the large difference in thermal expansion coefficient between the plastic film and the inorganic oxide thin film. And high gas barrier properties are not easily developed.

  Among them, a silicon oxide thin film formed by a plasma CVD method using an organosilane compound has been studied as a barrier layer exhibiting high gas barrier properties, and has been put into practical use in the food packaging field. Patent Document 3 reports that the adhesion and transparency are improved by controlling the carbon concentration and the composition of the silicon oxide thin film, but it is described that the water vapor barrier property is slightly inferior, and has a high gas barrier property. Gas barrier properties are insufficient for FPDs such as required electronic paper, LCD, and organic EL.

JP 2003-255562 A JP 2005-298634 A Japanese Patent Laid-Open No. 11-322981

  An object of the present invention is to solve the problem of insufficient dimensional stability and gas barrier properties, for example, as a plastic substrate for flexible FPD, and particularly to provide a gas barrier laminate film excellent in water vapor barrier properties and dimensional stability. There is to do.

According to the first aspect of the present invention, an anchor layer is formed between a gas barrier layer made of silicon oxide represented by SiOxCy, the base material layer, and the gas barrier layer on at least one surface of the base material layer made of a plastic film. In gas barrier laminate film,
The base material layer has a thermal expansion coefficient αs of 20 ppm / ° C. ≦ αs ≦ 80 ppm / ° C., and a humidity expansion coefficient βs of 10 ppm /% RH ≦ βs ≦ 30 ppm /% RH,
The gas barrier layer has a thermal expansion coefficient αb smaller than 20 ppm / ° C. and a humidity expansion coefficient βb smaller than 10 ppm /% RH,
In the gas barrier layer SiOxCy, the value of x is 1.5 ≦ x ≦ 2.0, the value of y is 0.05 ≦ y ≦ 0.5, and the thickness is 10 nm or more and 1000 nm or less,
The anchor layer has a thermal expansion coefficient αa smaller than 20 ppm / ° C. and a humidity expansion coefficient βa smaller than 10 ppm /% RH. The base material layer, the anchor layer, and the gas barrier layer have a thermal expansion coefficient of αs>αa> αb. And a humidity expansion coefficient has a relationship of βs>βa> βb.

  ADVANTAGE OF THE INVENTION According to this invention, the gas barrier property laminated | multilayer film which can be used suitably when especially high gas barrier property and dimensional stability are required as a board | substrate for flexible FPD can be provided.

It is a schematic sectional drawing which shows an example of the gas barrier laminated film of this invention. It is a figure which shows the measurement result of the dimensional change in the film of Example 1, 2, 3 and Comparative Example 1,2.

  Hereinafter, the form for implementing the gas-barrier laminated film of this invention is demonstrated along drawing. FIG. 1 is a schematic cross-sectional view showing an example of a highly transparent gas barrier laminate film of the present invention. A gas barrier layer 2 made of silicon oxide represented by SiOxCy is laminated on the base material layer 1.

  In the gas barrier laminate film of the present invention, the gas barrier layer 2 is formed on the base layer 1 and is made of silicon oxide, prevents thermal expansion of the base layer 1, and causes dimensional deformation due to water absorption or drying of the base layer 1. The function to prevent is expressed.

  In the gas barrier laminate film of the present invention, the smaller the carbon component of the gas barrier layer 2 represented by SiOxCy, the higher the Young's modulus and the less the film is deformed. Therefore, the base layer 1 is deformed by thermal expansion, water absorption and drying. It becomes possible to suppress. However, due to lack of flexibility, there is a problem that cracks are generated due to internal stress of the gas barrier layer itself and gas barrier properties are reduced, or adhesion with the base material layer 1 is reduced. In order to relieve such internal stress, y in the gas barrier layer SiOxCy is preferably 0.05 or more, and more preferably 0.1 or more. On the other hand, the more the carbon component of the gas barrier layer 2 is, the more flexible the film becomes and cracks are less likely to occur. However, the transparency decreases with the increase in the carbon component, so the transparency is required for FPDs such as electronic paper and organic EL. In the case of a plastic substrate, it is necessary not to increase the carbon component of the gas barrier layer 2 excessively, and it is preferable to set y to 0.5 or less. When higher transparency is required, y is set to 0.3. The following is preferable. Further, in the gas barrier laminate film of the present invention, there is no problem even if y is a different value in the gas barrier layer 2. For example, in the depth direction of the gas barrier layer 2, this y is increased or decreased in the opposite direction. You can also do it.

Further, regarding the oxygen component of the gas barrier layer 2 represented by SiOxCy, there is a general tendency that transparency is improved by bringing x closer to 2, and conversely, by reducing x from 2, Gas barrier properties tend to improve.
That is, when x is too large, both of transparency and gas aria properties are adversely affected. Therefore, x is preferably 2.0 or less, and more highly transparent and high gas barrier properties can be achieved at the same time. Therefore, it is preferably 1.9 or less.
In addition, when x is less than 1.5, the transparency is remarkably deteriorated and is not suitable for plastic substrates for FPDs such as electronic paper and organic EL that require transparency. It is preferable that x is 1.6 or more when higher transparency is required.
Therefore, the practical range of x indicating the composition ratio of the oxygen component is 1.5 or more and 2.0 or less. Within such a range of x, both high transparency and high gas barrier properties are achieved. In order to achieve this, x is preferably 1.6 or more and 1.9 or less.
Further, in the gas barrier laminate film of the present invention, there is no problem even if x is a different value in the gas barrier layer 2. For example, x is increased or decreased in the depth direction of the gas barrier layer 2. You can also do it.

  The film thickness of the gas barrier layer 2 is preferably 10 nm or more and 1000 nm or less. If the film thickness is less than 10 nm, the function as a gas barrier material cannot be sufficiently achieved, and if it exceeds 1000 nm, the gas barrier layer 2 is likely to crack, and the optical characteristics of the gas barrier laminate can be controlled. It becomes difficult.

  In the gas barrier laminate film of the present invention, the method for forming the gas barrier layer 2 is not particularly limited, but the gas barrier layer 2 made of silicon oxide is formed on the surface of the base material layer 1 in a vacuum, In order to develop a high gas barrier property, a plasma chemical vapor deposition (CVD) method is preferable at present, and the film can be formed on one or both surfaces of the base material layer made of the plastic film. Further, it is possible to perform continuous vapor deposition by taking up the characteristics of the plastic substrate, and it is preferable to use a wind-up vacuum deposition apparatus. As the plasma generator, a low-temperature plasma generator such as direct current (DC) plasma, low-frequency plasma, high-frequency plasma, pulse wave plasma, tripolar plasma, or microwave plasma is used.

  The gas barrier layer 2 made of silicon oxide laminated by the plasma CVD method can be formed using a silane compound having carbon in the molecule and oxygen gas as raw materials, and is formed by adding an inert gas to the raw materials. You can also. Examples of silane compounds having carbon in the molecule include tetraethoxysilane (TEOS), tetramethoxysilane (TMOS), tetramethylsilane (TMS), hexamethyldisiloxane (HMDSO), tetramethyldisiloxane, and methyltrimethoxysilane. A relatively low molecular weight silane compound may be selected, and one or more of these silane compounds may be selected.

  In the film formation by the plasma CVD method, the silane compound vaporized and mixed with oxygen gas is introduced between the electrodes, and the plasma is formed by applying electric power with a low-temperature plasma generator and can be laminated on the anchor layer. . In the plasma CVD method, the film quality of the gas barrier layer 2 made of silicon oxide can be changed by various methods, and the composition ratio of the oxygen component and the carbon component of the gas barrier layer 2 can be increased and decreased relatively easily. For example, changing the silane compound and the gas type, mixing ratio of the silane compound and oxygen gas, increase / decrease in applied power, and the like are effective techniques.

  In the gas barrier laminate film of the present invention, the base material layer 1 has a thermal expansion coefficient αs of 20 ppm / ° C. or more and 200 ppm / ° C. or less, and a humidity expansion coefficient βs of 10 ppm /% RH or more and 30 ppm /% RH or less. In particular, when high dimensional stability is required, it is made of a transparent plastic film having a thermal expansion coefficient αs of 80 ppm / ° C. or less. Examples of transparent plastic films include polyester films such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin films such as polyethylene and polypropylene, polyether sulfone (PES), polystyrene films, polyamide films, and polyvinyl chloride. Films, polycarbonate films, polyacrylonitrile films, polyimide films, biodegradable plastic films such as polylactic acid, and the like are used.

  These transparent plastic films may be either stretched or unstretched, but those having excellent mechanical strength and dimensional stability are preferred. In particular, from the standpoints of heat resistance and dimensional stability, polyethylene terephthalate stretched biaxially is preferably used as the packaging material, and electronic paper, organic EL, and the like that require higher heat resistance and dimensional stability. For these FPDs, polyethylene naphthalate, polyether sulfone, polycarbonate and the like are preferably used. Moreover, the transparent plastic film may contain additives such as an antistatic agent, an ultraviolet ray preventing agent, a plasticizer, and a lubricant. Further, in the transparent plastic film, the surface on the side where other layers are laminated may be subjected to corona treatment, low temperature plasma treatment, ion bombardment treatment, chemical treatment, solvent treatment, etc. in order to improve adhesion. .

The thermal expansion coefficient αs and the humidity expansion coefficient βs of the base material layer 1 can be controlled by, for example, the type and amount of additives such as fillers and the degree of stretching during film formation. May be a plastic film having a thermal expansion coefficient αs of 20 ppm / ° C. ≦ αs ≦ 80 ppm / ° C. and a humidity expansion coefficient βs of 10 ppm /% RH ≦ βs ≦ 30 ppm /% RH, It is not limited to the control method of the humidity expansion coefficient βs.

  The thickness of the base material layer 1 made of these transparent plastic films is not particularly limited, but for FPDs such as electronic paper and organic EL, in consideration of processing suitability, it is practically 25 μm. It is preferably in the range of 200 μm or less.

  In the gas barrier laminate film of the present invention, an anchor layer may be formed between the base material layer 1 and the gas barrier layer 2, and the anchor layer includes a base material 1 made of a plastic film, a gas barrier layer 2 made of silicon oxide, The function of improving the adhesion and improving the gas barrier property is exhibited.

  The base material layer 1 made of a plastic film and the gas barrier layer 2 made of silicon oxide have a large difference in thermal expansion coefficient and humidity expansion coefficient, and when they are laminated, cracks may occur from the interface between the layers and adhesion may be lowered. Therefore, by making the thermal expansion coefficient αa and the humidity expansion coefficient βa of the anchor layer smaller than the thermal expansion coefficient αs and the humidity expansion coefficient βs of the base material layer 1 and larger than the thermal expansion coefficient αb and the humidity expansion coefficient βb of the gas barrier layer 2. As a result, the expansion coefficient changes gradually, and the occurrence of cracks can be suppressed. At this time, it is preferable that the thermal expansion coefficient and the humidity expansion coefficient of the anchor layer are approximately between those of the base material layer 1 and those of the gas barrier layer 2.

  The thickness of the anchor layer is preferably 10 nm or more and 500 nm or less. If the film thickness is less than 10 nm, it is difficult to form a uniform film, and gas barrier properties and adhesion may be reduced. If it exceeds 500 nm, it becomes difficult to control the optical properties of the gas barrier laminate.

The anchor layer preferably contains at least a polyol and an isocyanate compound.
The polyols are those having a hydroxyl group at the terminal of a polymer compound such as acrylic polyol, polyester polyol, polyvinyl acetal, etc., and react with an isocyanate group of an isocyanate compound described later to form a urethane bond. Considering the reaction with the isocyanate compound, the hydroxyl value of the polyol is preferably between 5 and 200 KOHmg / g.
An isocyanate compound is added in order to improve the adhesiveness with the base material layer 1 or the gas barrier layer 2 by the urethane bond which reacts with the said polyols. In general, TDI (tolylene diisocyanate), MDI (diphenylmethane diisocyanate), XDI (xylylene diisocyanate), HDI (hexamethylene diisocyanate), and adducts and nurates thereof can be used. Such a urethane polymer may be used. It is preferable to add an isocyanate compound so that the isocyanate group derived from an isocyanate compound and the hydroxyl group derived from a polyol may become an equivalent, and the addition method can use a well-known method and is not specifically limited.

In the gas barrier laminate film of the present invention, the anchor layer can be formed by preparing a mixed solution in which polyols and an isocyanate compound are mixed at an arbitrary mixing ratio, and coating the mixed solution on the base material layer 1. The mixed solution may be diluted to an arbitrary concentration by adding a solvent.
The anchor layer is coated on one surface or both surfaces of the base material layer 1 using a known coating method such as dipping method, roll coating method, gravure coating method, air knife coating method, comma coating method, etc., and then the solvent is removed. It can be obtained by drying and curing the coating film.

  The thermal expansion coefficient and humidity expansion coefficient of the gas barrier layer 2 and the anchor layer can be controlled by, for example, the composition ratio of SiOxCy in the case of the gas barrier layer 2 and the material and the mixing ratio contained in the anchor layer. The gas barrier layer 2 and the anchor layer of the invention are not limited to the above control method as long as the thermal expansion coefficient and the humidity expansion coefficient satisfy the above ranges.

  As a method for measuring the thermal expansion coefficient, for example, a thermal mechanical analyzer (TMA (Thermo Mechanical Analysis)) is used to raise the temperature of the sample at a constant temperature, and the amount of thermal expansion before and after the temperature rise. Measure the thermal expansion per 1 ℃. The humidity expansion coefficient measures the rate of change (%) in the size of the sample per rate of change (%) in relative humidity.

  When the gas barrier laminate film of the present invention is used for a flexible FPD substrate, high light transmittance is required. Therefore, the spectral transmittance at a wavelength of 400 nm to 1000 nm of the gas barrier laminate film is preferably 85% or more, and 90 % Or more is more preferable.

  EXAMPLES Hereinafter, although an Example and a comparative example further demonstrate this invention, this invention is not restrict | limited to the following example.

Example 1
As the base material layer 1, a polyethylene terephthalate (PET) film having a thickness of 100 μm, a thermal expansion coefficient of 100 ppm / ° C., and a humidity expansion coefficient of 30 ppm /% RH is prepared, and using a plasma CVD method, hexamethyldisiloxane (HMDSO) A gas barrier having a thickness of 60 nm represented by SiOxCy (x = 1.8, y = 0.1) is generated by introducing a mixed gas of / oxygen = 10/100 sccm between the electrodes and applying electric power of 0.5 kW to generate plasma. Layer 2 (thermal expansion coefficient: 0.5 ppm / ° C., humidity expansion coefficient: 0.1 ppm /% RH) was laminated on both surfaces of the base material layer 1. Thus, the gas barrier laminate film of Example 1 was produced.

Example 2
A polyethylene naphthalate (PEN) film having a thickness of 100 μm, a thermal expansion coefficient of 20 ppm / ° C., and a humidity expansion coefficient of 20 ppm /% RH is prepared as the base material layer 1, and the gas barrier layer 2 is laminated in the same manner as in Example 1. And the gas-barrier laminated film of Example 2 was produced.

Example 3
In the gas barrier laminate film of Example 2, a mixed liquid composed of acrylic polyol and hexamethylene diisocyanate (HDI) was coated between the base material layer 1 and the gas barrier layer 2 by a gravure coating method, dried and cured, and then thickness A 60 nm anchor layer (thermal expansion coefficient: 15 ppm / ° C., humidity expansion coefficient: 10 ppm /% RH) was formed. Other than that was carried out similarly to Example 1, and produced the gas-barrier laminated film of Example 3. FIG.

Comparative Example 1
A polyethylene naphthalate (PEN) film having a thickness of 100 μm was prepared and used as Comparative Example 1.

Comparative Example 2
In the gas barrier laminate film of Example 1, the gas barrier layer 2 represented by SiOx (x = 1.8, y = 0.01) was laminated on both surfaces of the base material layer 1 in the same manner as in Example 1 for comparison. The gas barrier laminate film of Example 2 was produced.

Comparative evaluation Dimensional change In the films of Examples 1, 2, and 3 and Comparative Examples 1 and 2, 8 points were marked on a 200 mm × 200 mm region, heated at 110 ° C. (humidity free) for 6 hours, and then 60 ° C./90% RH. The film was held for 6 hours, and the dimensional change of the film was measured when heated again at 110 ° C. (humidity free) for 6 hours. The measurement results are shown in FIG.
2. The film water vapor transmission rate Examples 1, 2, 3 and Comparative Examples 1 and 2, the water vapor transmission rate after heating before and heated ^(g / m 2 / 24h) was measured. For the measurement, a water vapor permeability meter (MOCON PERMATRAN-W 3/33) manufactured by Modern Control was used, and the measurement was performed in an atmosphere of 40 ° C. and 90% RH. The measurement results are shown in Table 1.

  As can be seen from FIG. 2 and Table 1, the gas barrier laminated films of Examples 1, 2, and 3 have a small dimensional change even when kept in a heated / wet environment and low water vapor permeability. On the other hand, the PEN film of Comparative Example 1 has a large dimensional change in a heated / wet environment and a high water vapor permeability. Moreover, the gas barrier laminate film of Comparative Example 2 started to increase in dimensional change under a wet environment, and the water vapor permeability after heating was significantly deteriorated. As a result of observation with an optical microscope, it was confirmed that cracks occurred in the gas barrier layer.

1 ... base material layer, 2 ... gas barrier layer.

Claims (1)

In the gas barrier laminated film in which the gas barrier layer made of silicon oxide represented by SiOxCy and the anchor layer is formed between the base material layer and the gas barrier layer on at least one surface of the base material layer made of a plastic film,
The substrate layer has a thermal expansion coefficient αs of 20 ppm / ° C. ≦ αs ≦ 80 ppm / ° C., and a humidity expansion coefficient βs of 10 ppm /% RH ≦ βs ≦ 30 ppm /% RH,
The gas barrier layer has a thermal expansion coefficient αb of less than 20 ppm / ° C. and a humidity expansion coefficient βb of less than 10 ppm /% RH;
The value of x in SiOxCy of the gas barrier layer is 1.5 ≦ x ≦ 2.0, the value of y is 0.05 ≦ y ≦ 0.5, and the thickness is 10 nm or more and 1000 nm or less,
The anchor layer has a thermal expansion coefficient αa smaller than 20 ppm / ° C. and a humidity expansion coefficient βa smaller than 10 ppm /% RH. The base material layer, the anchor layer, and the gas barrier layer have a thermal expansion coefficient of αs>αa> αb. And a humidity expansion coefficient has a relationship of βs>βa> βb.

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