JP5412850B2 - Gas barrier laminate - Google Patents

Description

  The present invention relates to a gas barrier laminate excellent in barrier properties and durability used for industrial materials. In particular, the present invention relates to a barrier laminate for a back surface protection sheet that needs to protect module cells and wiring of a solar battery and has excellent barrier properties and durability. Further, the application is not limited to this, and application development is possible.

  Gas barrier laminates are used as packaging materials for foods, precision electronic components, and pharmaceuticals, and in order to suppress the alteration of the contents and maintain their functions and properties, the oxygen, water vapor, and other contents that pass through the packaging material are altered. It is necessary to prevent the influence of the gas or light to be generated, and it has been required to have a gas barrier property or the like for blocking these. In recent years, this gas barrier laminate has come to be used as an industrial material application represented by a back surface protection sheet that is a member of a solar cell module.

  Conventionally, metal foil such as aluminum, which has little influence on temperature and humidity, has been generally used as the gas barrier layer for the above-mentioned back surface protection sheet. However, metal foil is poorly insulated from solar cells and wiring due to deterioration over time. There was a problem with the drawbacks.

  Therefore, as a packaging material that overcomes these drawbacks, for example, a film in which a silicon oxide vapor deposition film is formed on a fluororesin film as described in the patent literature by a vacuum deposition method has been developed (Patent Literature 1). ). Since this vapor-deposited film has transparency and gas barrier properties such as oxygen and water vapor, it is suitable as a packaging material having insulating properties and transparency that cannot be obtained with a metal foil or the like.

JP-A-10-308521

  However, a conventional film in which a low-density silicon oxide film is laminated has a drawback that the barrier property is deteriorated under a long-time high-temperature and high-humidity environment because the silicon oxide film is deteriorated.

  In order to solve this problem, an attempt has been made to suppress the deterioration of the inorganic oxide layer laminated on the plastic film substrate by applying an overcoat such as a plastic resin system on the silicon oxide film. ing.

  However, conventionally, if it is attempted to suppress the deterioration of the silicon oxide film by the resin-based overcoat or the silica sol-based overcoat, the number of steps of the gas barrier laminate is increased, and these components sufficiently suppress the deterioration of the silicon oxide film. I couldn't.

  The present invention has been made to solve the above problems, and provides a gas barrier laminate in which the barrier property does not deteriorate even when a test is performed in a high temperature and high humidity environment by changing the film quality of the silicon oxide film.

  The present invention has found that the above object can be achieved by setting the density and O / Si of the silicon oxide film to specific values.

In the gas barrier laminate in which the silicon oxide film is laminated on both sides or one side of the plastic film substrate, the center line average roughness Ra of the surface of the plastic film substrate on which the silicon oxide film is laminated is It is ^{3 to} 30 nm, and the density of the silicon oxide film calculated by high-resolution Rutherford backscattering (HR-RBS) measurement is in the range of 2.4 to 2.6 g / cm ^3. A gas barrier laminate.

  The invention according to claim 2 is characterized in that, for the silicon oxide film, a ratio of oxygen to silicon (O / Si) calculated by HR-RBS method measurement is in a range of 1.4 to 2.0. The gas barrier laminate according to claim 1.

  A third aspect of the present invention is the gas barrier laminate according to the first or second aspect, wherein the silicon oxide film has a thickness of 10 to 150 nm.

The invention according to claim 4 is the gas barrier laminate according to any one of claims 1 to 3 , wherein an anchor coat layer is provided between the plastic film substrate and the silicon oxide film. .

  The invention of claim 5 is characterized in that the anchor coat layer is formed of one or more kinds of resins selected from polyester resins, urethane resins, acrylic resins, and oxazoline group-containing resins. It is a gas barrier laminated body of description.

According to a sixth aspect of the invention, the gas barrier laminate according to any one of claims 1 to 3, characterized in that the plastic film reactive ion etching (RIE) processing plasma utilized on the substrate is subjected It is.

  The invention according to claim 7 is characterized in that the RIE treatment is performed at least once using one kind of gas of argon, nitrogen, oxygen, hydrogen, or a mixed gas thereof. The gas barrier laminate according to claim 6.

  According to the present invention, when such a gas barrier laminate is used, it is possible to provide a gas barrier laminate in which the deterioration of the silicon oxide film is suppressed even under a high temperature and high humidity environment, and the barrier properties are not deteriorated. Specifically, the invention according to claims 1 and 2 provides a chemical structure in which the barrier property does not deteriorate under a high temperature and high humidity environment. According to the third aspect of the present invention, the film thickness is such that the barrier property does not deteriorate in a high temperature and high humidity environment. According to the invention described in claims 4 to 6, a structure in which the plastic film substrate and the silicon oxide film are not peeled off in a high temperature and high humidity environment. According to the seventh aspect of the present invention, it is possible to perform processing that does not pollute the environment as compared with chemical processing using a processing solution.

Sectional drawing of the gas barrier laminated body of this invention. RBS spectrum measured by high resolution Rutherford backscattering method. Depth profile converted from RBS spectrum. Schematic schematic diagram when planar plasma treatment is performed. Sectional drawing of a holo anode plasma processing device.

  Hereinafter, embodiments of the present invention will be described. FIG. 1 is a cross-sectional view illustrating a gas barrier laminate according to the present invention. The plastic film substrate 1 and the silicon oxide film 2 have a structure in which a treatment layer 3 is formed on the surface of the plastic film substrate between which the pretreatment by RIE treatment using an anchor coat layer or plasma is formed.

  The gas barrier laminate of the present invention controls the density of the silicon oxide film. As a result, not only can the gas barrier properties such as oxygen permeability and water vapor permeability be improved and cracks can be prevented, but also barrier degradation can be suppressed even in a high temperature and high humidity environment.

  The gas barrier laminate of the present invention is based on the following knowledge of the present inventors. In the high-resolution Rutherford backscattering method (HR-RBS), He ions accelerated to several hundred keV are implanted into a substance to be measured, and the backscattered He ions are detected by a deflection magnetic field type energy analyzer. As an analysis procedure, the channel on the horizontal axis is converted into the energy of scattered ions with reference to the midpoint of the 0 high energy side edge. Next, the system background is subtracted, and a depth profile is obtained by simulation fitting. This analysis enables density measurement and composition analysis.

Usually, the density of SiO ₂ such as crystalline quartz shows 2.65 g / cm ³ , but vapor deposition is usually lower than this value, but at a density lower than a certain value, gas barrier performance Is not fully demonstrated.

In contrast, the silicon oxide film of the gas barrier laminate of the present invention can exhibit extremely good barrier properties by adjusting the density to 1.9 to 2.6 g / cm ^3, and can be used in a high temperature and high humidity environment. However, it is difficult to cause barrier degradation.

  FIG. 2 shows an example of an HR-RBS spectrum measured by the HR-RBS method and a simulation result. The horizontal axis represents the energy of the backscattered ions, and the vertical axis represents the yield of ions. The measured peak appears at the energy value specific to the element, and the peak width increases in proportion to the thickness. In the simulation, peak fitting is performed by dedicated software attached to the apparatus, and converted to a depth profile used for density calculation. FIG. 3 shows an example of the depth profile. From this depth profile, the volume density can be calculated from the integrated value of the composition ratio and the surface density at each depth.

  The plastic film substrate 1 described above is a plastic material, and is preferably a transparent plastic film substrate if possible in order to make use of the transparency of the silicon oxide film. Examples of plastic film substrates include polyester films such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin films such as polyethylene and polypropylene, polystyrene films, polyamide films, polycarbonate films, polyacryl nitrile films, polyimide films Etc. The plastic film substrate may be either stretched or unstretched, and preferably has mechanical strength and dimensional stability. Among these, a polyethylene terephthalate film or a polyamide film arbitrarily stretched in the biaxial direction is preferably used. Further, a known additive such as an antistatic agent, an ultraviolet absorber, a plasticizer, or a lubricant may be used on the surface of the plastic film substrate opposite to the surface on which the silicon oxide film is provided.

  The thickness of the plastic film substrate is not particularly limited, but considering the workability when forming a silicon oxide film, it is practically in the range of 3 to 200 μm, particularly 6 to 50 μm. Is preferred. When the thickness is 3 μm or less, wrinkling or film breakage occurs when processing with a winding device, and when the thickness is 200 μm or more, the flexibility of the film is lowered, so that processing becomes difficult with the winding device. .

  In addition, in consideration of suitability as an industrial material or packaging material, films having different properties other than the silicon oxide film can be laminated. For example, a polyester film such as polyethylene terephthalate, a fluorine-based resin film such as a polyvinyl fluoride film or a polyfluorinated divinyl, and the like can be considered, but other resin films can be laminated.

  The center line average roughness Ra of the surface on which the silicon oxide film of the plastic film substrate used in the gas barrier laminate of the present invention is laminated is preferably 10 to 20 nm. If the surface of the plastic film substrate is in the above range, the density of the silicon oxide film can be accurately determined by HR-RBS measurement while improving the adhesion between the silicon oxide film or anchor coat layer and the plastic film substrate. Can be identified. As a method for measuring the film density, there are known measurement methods such as X-ray reflectivity measurement. However, these methods are not suitable if the surface of the plastic film substrate on which the film to be measured is laminated is not smooth. Is difficult to measure accurately, and when the roughness of the plastic film substrate surface is large, the composition could not be controlled to a desired film density. On the other hand, since the HR-RBS measurement can accurately measure the film density even when the plastic film substrate surface is within the above-mentioned roughness range, the roughness of the plastic film substrate surface for improving adhesion It is possible to accurately control the density of the laminated films while ensuring the above.

  In the gas barrier laminate of the present invention, an anchor coat layer is preferably provided between the plastic film substrate and the silicon oxide film in order to improve the adhesion between the plastic film substrate and the silicon oxide film. As a method for forming the anchor coat layer, a method of applying an anchor coat to a plastic film substrate can be adopted, and a silicon oxide film may be formed on the formed anchor coat layer.

  As an anchor coating agent, solvent-soluble or water-soluble polyester resin, isocyanate resin, urethane resin, acrylic resin, vinyl alcohol resin, ethylene vinyl alcohol resin, vinyl modified resin, epoxy resin, oxazoline phase-containing resin, modified styrene resin, Modified silicone resin and alkyl titanate can be used alone or in combination of two or more.

  The thickness of the anchor coat layer is usually 0.005 to 5 μm, preferably 0.01 to 1 μm. When the film thickness exceeds 5 μm, the slipperiness may be deteriorated or the film may be easily peeled off from the plastic film substrate due to the internal stress of the anchor coat layer itself. On the other hand, if the film thickness is less than 0.005 μm, the film thickness may not be uniform.

  Further, in order to improve anchor applicability and adhesion to the film, the surface of the plastic film substrate may be subjected to a discharge treatment.

  In the gas barrier laminate of the present invention, the surface of the plastic film substrate on which the silicon oxide film is laminated may be pretreated by reactive ion etching (RIE) using plasma. By performing this RIE treatment, the generated radicals and ions are used to remove the surface impurities by chemical effects such as giving functional groups to the surface of the plastic film substrate, and ion etching, It is possible to simultaneously obtain two physical effects such as increasing the surface roughness. As a result, the adhesion between the plastic film substrate and the silicon oxide film is improved, and a structure is obtained in which neither peels off in a high temperature and high humidity environment.

  In the present invention, the RIE process can be performed by a roll-in type in-line apparatus by applying a voltage to a cooling drum on which a plastic film substrate is installed to form a planar type (FIG. 4), or a holo anode plasma. There is a method (FIG. 5) in which processing is performed using a processor.

  If processing is performed in a planar type, the plastic film substrate can be placed on the cathode side, and processing by RIE can be performed by obtaining a high self-bias (FIG. 4). If the application electrode is installed on the opposite side of the drum or guide roll, as is normally done with inline processing, the plastic film substrate is installed on the anode (anode) side (FIG. 5). At this time, the plastic film substrate cannot obtain a high self-bias, and since radicals act only on the surface of the plastic film substrate and only undergo chemical reaction, so-called plasma etching is performed. The adhesion remains low.

  The holo anode / plasma processor has a hollow anode, and the area of the anode (Sa) is such that Sa> Sc compared to the substrate area (Sc) as a counter electrode. (FIG. 4). By increasing the area of the anode, a large self-bias can be generated on the cathode (plastic film substrate) as a counter electrode. This large self-bias enables stable and powerful surface treatment. More preferably, a more powerful and stable plasma surface treatment is performed at high speed by incorporating a magnet into the holo anode electrode to form a magnetic assist holo anode. The magnetic field generated from the magnetic electrode can further enhance the plasma confinement effect and obtain a high ion current density with a large self-bias.

  Argon, oxygen, nitrogen, and hydrogen can be used as the gas species for performing the pretreatment by RIE. These gases may be used alone, or two or more kinds of gases may be mixed and used. Moreover, you may process continuously using 2 or more processing apparatuses. At this time, it is not necessary to use the same two or more processing units, and the processing may be performed continuously using a holo anode / plasma processing unit after the planar type processing.

  Next, the silicon oxide film 2 will be described in detail. The ratio of oxygen to silicon (O / Si) calculated by HR-RBS measurement of the silicon oxide film is preferably 1.4 to 2.0. When O / Si is smaller than 1.4, the barrier property is lowered, and the barrier layer is colored to lose transparency. On the other hand, when the value is larger than 2.0, the barrier film has a large residual stress, so that a film defect such as a crack is likely to occur and the barrier property is remarkably lowered.

  The thickness of the silicon oxide film is generally preferably in the range of 5 to 300 nm, and the value is appropriately selected. However, if the film thickness is less than 5 nm, a uniform film may not be obtained or the film thickness may not be sufficient, and the function as a gas barrier material may not be sufficiently achieved. Further, when the film thickness exceeds 300 nm, the flexibility cannot be maintained due to the residual stress of the thin film, and there is a problem because the thin film may be cracked due to external factors after film formation. More preferably, it is in the range of 10 to 150 nm.

  As a method for laminating a deposited thin film layer made of silicon oxide on a plastic film, a vacuum deposition method, a sputtering method, an ion plating method, a plasma vapor deposition method (CVD), or the like can be used. However, in view of productivity, the vacuum deposition method is the best at present. As the heating means of the vacuum evaporation method, it is preferable to use any one of an electron beam heating method, a resistance heating method, and an induction heating method, but in consideration of the wide selection of the evaporation material, the electron beam heating method or the resistance heating method is used. It is more preferable to use the method. Moreover, in order to improve the adhesiveness of a vapor deposition thin film layer and a plastic film base material, and the denseness of a vapor deposition thin film layer, it is also possible to vapor-deposit using a plasma assist method or an ion beam assist method. In order to increase the transparency of the deposited film, it is possible to use reactive deposition in which various gases such as oxygen are blown during the deposition.

  An overcoat layer can be formed on the silicon oxide film in order to improve protection and adhesion. As this overcoat layer, solvent-soluble or water-soluble polyester resin, isocyanate resin, urethane resin, acrylic resin, vinyl alcohol resin, EVOH resin, vinyl-modified resin, epoxy resin, oxazoline group-containing resin, modified styrene resin, A layer composed of a modified silicone resin and an alkyl titanate alone or in combination of two or more can be provided. Further, as the overcoat layer, one or more selected from silica sol, alumina sol, particulate inorganic filler and layered inorganic filler are added to improve the barrier property, wear property and slipperiness, or in the presence of these one particles. An overcoat layer made of the above resin obtained by polymerizing or condensing the resin is preferred.

  Examples of the gas barrier laminate of the present invention will be specifically described below. The present invention is not limited to these examples.

[Density measurement of silicon oxide film by high-resolution Rutherford backscattering method (HR-RBS method)]
The measuring device used was a high resolution RBS analyzer HRBS500 manufactured by Kobe Steel. The sample was irradiated with He ions having an energy of 480 keV at an angle of 45 ° with respect to the normal of the sample surface, and the scattered He ions were detected by a polarized magnetic field type energy analyzer at a scattering angle of 90 ° (set value). At this time, the sample current was 15 nA, the irradiation amount was 4 μC, and the measurement energy range was 210 to 380 keV. The obtained spectrum was subjected to simulation fitting to convert it into a depth profile, and the volume density was calculated.

<Example 1>
Pretreatment by reactive ion etching (RIE) was performed on one side of a PET film having a thickness of 12 μm (P60 manufactured by Toray Industries, Inc.) using a holo anode plasma processing apparatus as a processing method. At this time, a high frequency power source having a frequency of 13.56 MHz was used for the electrodes, and argon gas was used for the processing gas. On top of this, a resistance heating method is used, the pressure is set to 5.1 × 10 ⁻² Pa as film forming conditions, 500 sccm of argon is introduced as an introduction gas, and a silicon oxide film is formed to a thickness of about 40 nm to form a gas barrier laminate. The body was made. The film density at this time was 2.4 g / cm ³ and O / Si was 1.8.

<Example 2>
A gas barrier laminate was produced in the same manner as in Example 1 except that the amount of introduced gas was 1000 sccm. The film density was 2.2 g / cm ³ and O / Si was 1.7.

<Example 3>
A gas barrier laminate was produced in the same manner as in Example 1 except that the amount of introduced gas was 1500 sccm. The film density was 2.0 g / cm ³ and O / Si was 1.6.

<Example 4>
A gas barrier laminate was produced in the same manner as in Example 1 except that the amount of introduced gas was 2000 sccm. The film density was 1.9 g / cm ³ and O / Si was 2.0.

<Example 5>
A CVD method is used on the same plastic film substrate as in Example 1, the pressure is set to 2.3 × 10 ⁻¹ Pa, oxygen is introduced at 200 sccm, and a silicon oxide film is formed to a thickness of about 20 nm. Thus, a gas barrier laminate was produced. The film density was 2.6 g / cm ³ and O / Si was 1.9.

<Comparative Example 1>
A gas barrier laminate was produced in the same manner as in Example 1 except that the amount of introduced gas was 2500 sccm. The film density was 1.8 g / cm ³ and O / Si was 1.3.

<Comparative example 2>
A gas barrier laminate was produced in the same manner as in Example 1 except that argon was introduced at 1500 sccm and oxygen was introduced at 500 sccm as a mixed gas. The film density was 1.8 g / cm ³ and O / Si was 1.3.

<Evaluation>
About the sample gas barrier laminate, oxygen permeability (cc / m ² · day) and water vapor permeability (g / m ² · day) were measured as an indicator of gas barrier properties before and after an environment with a temperature and humidity of 85 ° C. and 85% for 1000 hours. did. The measuring method was performed using the Mocon method, and the measurement conditions at that time were an oxygen permeability of 30 ° C.-70% RH and a water vapor permeability of 40 ° C.-90% RH. The measurement results are shown in Table 1. As evaluation criteria, the case where oxygen permeability was 5 cc / m ² · day or less and the water vapor permeability was 3 g / m ² · day or less was evaluated as “good”, and the case where the barrier property was more than the above range was evaluated as “bad”. .

Therefore, it was shown that the barrier properties of Comparative Examples 1 and 2 were poor except that the film density was adjusted to 1.9 to 2.6 g / cm ³ and O / Si was adjusted to 1.4 to 2.0.

  As described above, the gas barrier laminate of the present invention can provide a gas barrier laminate in which the barrier properties are hardly deteriorated even in a high-temperature and high-humidity environment because the film density and O / Si are within the scope of the claims.

  The present invention is used as a packaging material for foods, precision electronic components, and pharmaceuticals. In recent years, the present invention can be used for industrial materials as a back surface protection sheet as a member of a solar cell module.

DESCRIPTION OF SYMBOLS 1 ... Plastic film base material 2 ... Silicon oxide film 3 ... Pretreatment layer 4 ... Electrode 5 ... Plasma 6 ... Processing roll 7 ... Plastic film base material 8 ... Gas inlet 9 ... matching box 10 ... shielding plate

Claims (7)

In a gas barrier laminate in which a silicon oxide film is laminated on both sides or one side of a plastic film substrate,
The center line average roughness Ra of the surface on which the silicon oxide film of the plastic film substrate is laminated is 3 to 30 nm,
A gas barrier laminate, wherein the density of the silicon oxide film calculated by high-resolution Rutherford backscattering method (HR-RBS method) is in the range of 2.4 to 2.6 g / cm ³ .   2. The ratio of oxygen to silicon (O / Si) calculated by HR-RBS method measurement in the silicon oxide film is in a range of 1.4 to 2.0. 3. Gas barrier laminate.   The gas barrier laminate according to claim 1 or 2, wherein the silicon oxide film has a thickness of 10 to 150 nm. The gas barrier laminate according to any one of claims 1 to 3 , wherein an anchor coat layer is provided between the plastic film substrate and the silicon oxide film.   The gas barrier laminate according to claim 4, wherein the anchor coat layer is formed of one or more kinds of resins selected from a polyester resin, a urethane resin, an acrylic resin, and an oxazoline group-containing resin. The gas barrier laminate according to any one of claims 1 to 3 , wherein a reactive ion etching (RIE) process using plasma is performed on the plastic film substrate.   The gas barrier according to claim 6, wherein the RIE process is a process performed one or more times using one kind of gas of argon, nitrogen, oxygen, hydrogen, or a mixed gas thereof. Laminated body.

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