JP2008265232A - Gas barrier laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas barrier laminate having an excellent durability at high-temperature and high-humidity environments. <P>SOLUTION: The gas barrier laminate has an inorganic oxide layer 2 laminated on at least one side of a polyethylene naphthalate film 1. A reactive ion etching (RIE) treatment 3 utilizing plasma is given to the surface on which at least the inorganic oxide layer 2 of the polyethylene naphthalate film 1 is provided. When an X-ray photoelectron spectroscopy measurement (measurement conditions: an X-ray source is MgKα, and an X-ray output is 100 W) is applied on the surface subjected to the RIE treatment, the atomic number ratio (O/C) of oxygen and carbon is within the range of 0.20-0.40. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a gas barrier laminate excellent in durability for use as an industrial material. In particular, the present invention relates to a gas barrier laminate for a backside protective sheet excellent in durability, which is suitable for protecting module cells and wiring of a solar battery. 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, but 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 has overcome these drawbacks, for example, a film in which a silicon oxide vapor deposition film is formed on a fluororesin film as described in Patent Document 1 by a vacuum vapor deposition method has been developed. 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.

  However, in a film in which an inorganic oxide layer is laminated on a base material that has not been subjected to pretreatment as in the past, the adhesion between the base material and the inorganic oxide layer is weak. There is a drawback of causing lamination.

  In order to solve this problem, attempts have been made to improve the adhesion of an inorganic oxide layer laminated on a plastic substrate by in-line pretreatment by using plasma.

  However, conventionally, when plasma processing is performed in-line, an electrode for applying a voltage for generating plasma is installed on the opposite side rather than the drum side on which the substrate is provided. In the case of this apparatus, since the base material is installed on the anode side, a high self-bias cannot be obtained, and as a result, a high treatment effect cannot be exhibited.

In order to obtain a high self-bias, a DC discharge method can be used. However, if a high bias voltage is obtained by this method, the plasma mode changes from glow to arc, so a uniform treatment over a large area. Cannot be done.
JP-A-10-308521

  The present invention has been made in order to solve the above-described problems, and provides a gas barrier laminate in which adhesion between a polyethylene naphthalate (PEN) film and an inorganic oxide layer is strengthened and delamination does not occur even in a high temperature and high humidity environment. The purpose is to provide.

  The present invention has found that the above object can be achieved by using a PEN film having specific surface characteristics.

The invention according to claim 1 is a gas barrier laminate in which an inorganic oxide layer is laminated on at least one surface of a polyethylene naphthalate film,
Reactive ion etching (RIE) treatment using plasma is performed on at least the surface of the polyethylene naphthalate film on which the inorganic oxide layer is provided,
When X-ray photoelectron spectroscopic measurement of the surface subjected to the RIE treatment (measurement conditions: X-ray source MgKα, X-ray output 100 W) is performed, the atomic ratio (O / C) of the oxygen element to the carbon element is 0.20. It is in the range of -0.40, It is a gas barrier laminated body characterized by the above-mentioned.
The invention according to claim 2 is the functional group obtained from the analysis of the C1s waveform when X-ray photoelectron spectroscopy measurement (measurement conditions: X-ray source MgKα, X-ray output 100 W) of the surface subjected to the RIE treatment is performed. 2. The gas barrier laminate according to claim 1, wherein the ratio (C—O / C—C) is within a range of 0.10 to 0.25.
The invention according to claim 3 is the functional group obtained from the analysis of the C1s waveform when X-ray photoelectron spectroscopy measurement (measurement condition: X-ray source MgKα, X-ray output 100 W) of the surface subjected to the RIE treatment is performed. The gas barrier laminate according to claim 1 or 2, wherein the ratio (COO / C-C) is in the range of 0.10 to 0.25.
According to a fourth aspect of the present invention, the RIE process is a planar type plasma process in which a substrate is placed on the cathode side to which a voltage is directly applied, or a plasma process using a holo anode plasma processor. It is a gas barrier laminated body in any one of Claims 1-3 characterized by the above-mentioned.
The invention according to claim 5 is characterized in that 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. The gas barrier laminate according to any one of claims 1 to 4.
The invention according to claim 6 is the gas barrier laminate according to any one of claims 1 to 5, wherein the inorganic oxide layer is made of aluminum oxide, silicon oxide, or a mixture thereof. .
The invention according to claim 7 is the gas barrier laminate according to any one of claims 1 to 6, wherein the RIE treatment and the lamination of the inorganic oxide layer are performed by the same film forming machine. is there.

  The invention according to claim 1 is a gas barrier laminate in which an inorganic oxide layer is laminated on at least one surface of a polyethylene naphthalate film, and the surface on which at least the inorganic oxide layer of the polyethylene naphthalate film is provided. In addition, reactive ion etching (RIE) treatment using plasma was performed, and X-ray photoelectron spectroscopy measurement (measurement conditions: X-ray source MgKα, X-ray output 100 W) of the surface subjected to the RIE treatment was performed. In this case, the atomic ratio (O / C) of the oxygen element and the carbon element is in the range of 0.20 to 0.40. According to this configuration, by performing the RIE process, the element concentration can be controlled using the generated radicals and ions, and by setting (O / C) to 0.20 to 0.40, PEN Polar functional groups such as C—OH groups, C═O groups, and COOH groups are generated on the film surface, thereby strengthening the adhesion to the inorganic oxide film.

  The invention according to claim 2 is the functional group ratio obtained from the analysis of the C1s waveform when X-ray photoelectron spectroscopic measurement (measurement conditions: X-ray source MgKα, X-ray output 100 W) of the surface subjected to the RIE treatment is performed. (C-O / C-C) is in the range of 0.10 to 0.25. According to this configuration, the surface free energy is close to that of the inorganic oxide layer by controlling the molecular structure on the surface of the PEN film so that the functional group ratio (C—O / C—C) is 0.10 to 0.25. Thus, the adhesiveness can be strengthened.

  The invention according to claim 3 is the functional group ratio obtained from the analysis of the C1s waveform when X-ray photoelectron spectroscopic measurement (measurement condition: X-ray source MgKα, X-ray output 100 W) of the surface subjected to the RIE treatment is performed. (COO / C-C) is in the range of 0.10 to 0.25. According to this configuration, the surface free energy is close to that of the inorganic oxide layer by controlling the molecular structure on the surface of the PEN film to 0.10 to 0.25 as the functional group ratio (C—O / C—C). The adhesion can be strengthened.

  According to a fourth aspect of the present invention, in the RIE process, a planar type plasma process in which a substrate is installed on the cathode side (cooling drum side) to which a direct voltage is applied, or a plasma process using a holo anode plasma processor. It is characterized by being. According to this configuration, the PEN film surface can be treated more uniformly than arc discharge such as plasma treatment or corona treatment in which the base material is placed on the anode side, and a treatment depth of about 10 nm from the surface contributing to adhesion. Thus, a treatment layer can be formed.

  The invention according to claim 5 is characterized in that 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. . According to this structure, the process which does not pollute an environment compared with the chemical process using a process liquid is attained.

  The invention described in claim 6 is characterized in that the inorganic oxide layer is made of aluminum oxide, silicon oxide, or a mixture thereof. According to this configuration, the inorganic oxide layer becomes a harmless member for the environment during disposal and incineration as compared with a barrier laminated band using a metal foil or a metal thin film.

  The invention according to claim 7 is characterized in that the RIE treatment and the lamination of the inorganic oxide layer are performed by the same film forming machine (in-line film forming machine). According to this structure, productivity can be improved and the adhesiveness of a polyethylene naphthalate film and an inorganic oxide can be strengthened.

  According to the present invention, it is possible to provide a gas barrier laminate in which adhesion between a polyethylene naphthalate (PEN) film and an inorganic oxide layer is enhanced and delamination does not occur even in a high temperature and high humidity environment.

  Hereinafter, the present invention will be described in more detail.

  FIG. 1 is a cross-sectional view illustrating a gas barrier laminate according to the present invention. An inorganic oxide layer 2 is laminated on the surface of the PEN film 1. The surface of the PEN film 1 has a structure in which a pretreatment by reactive etching (RIE) using plasma is performed and a treatment layer 3 is formed.

  In the gas barrier laminate of the present invention, the surface of the PEN film 1 is pretreated by reactive ion etching (RIE) using plasma. By performing the treatment by RIE, the atomic number concentration and the functional group ratio of the elements on the surface of the PEN film 1 can be controlled using the generated radicals and ions. As a result, the adhesion between the PEN film 1 and the inorganic oxide layer 2 is strengthened, leading to improvement in gas barrier properties and prevention of crack generation, and delamination does not occur even in a high temperature and high humidity environment.

In the measurement by X-ray photoelectron spectroscopy (XPS measurement), it is possible to analyze the type and concentration of atoms in the depth region several nm from the surface of the substance to be measured, the type of atoms bonded to the atoms, and their bonding state.
In general, the PEN film has an atomic ratio (O / C) of about 0.30 in an untreated state where surface treatment such as plasma treatment is not performed. The C1s waveform can be separated into C—C, C—O, and COO bonds derived from the PEN molecular structure, and the peak intensity ratio is C—C: C—O: COO = 5: 1: 1. The ratio of C—C to C—O (C—O / C—C) is 0.20, and the ratio of C—C to COO (COO / C—C) is 0.20. Such (O / C), (C-O / C-C), (COO / C-C), and other untreated PEN films having no polar functional groups are If it is left in the environment, it tends to cause delamination with the deposited inorganic oxide film and has low adhesion.

  In contrast, the gas barrier laminate of the present invention is subjected to surface treatment by reactive ion etching (RIE) using plasma, whereby the film surface is modified and the atomic ratio (O / C) is 0. 20 to 0.40, the functional group ratio (C—O / C—C) is 0.10 to 0.25, and (COO / C—C) is 0.10 to 0.25. These exhibit extremely good adhesion with the inorganic oxide layer, and when left in a high-temperature and high-humidity environment, they hardly cause delamination with the inorganic oxide vapor-deposited film.

  FIG. 2 is a spectrum obtained by peak separation analysis of the C1s waveform on the surface of the untreated PEN film obtained by XPS measurement. The C1s waveform is separated into a C—C bond 4, a C—O bond 5, and a COO bond 6.

  The XPS measurement conditions in the present invention are an X-ray source MgKα, an X-ray output of 100 W, an analyzer transmission energy of 10 eV, and a measurement step of 0.1 eV.

  Also, known additives such as antistatic agents, ultraviolet absorbers, plasticizers, and lubricants can be used for the PEN film.

  The thickness of the PEN film is not particularly limited, but considering the workability when forming the inorganic oxide layer, the range of 3 to 200 μm is preferable for practical use, particularly 6 to 50 μm. preferable. When the thickness is less than 3 μm, wrinkles are generated and the film breaks when processed by a winding device. When the thickness exceeds 200 μm, the flexibility of the film is lowered, so that the processing becomes difficult with the winding device. In consideration of suitability as industrial materials and packaging materials, films having different properties other than the inorganic oxide layer can be laminated. For example, a polyester film such as polyethylene terephthalate, a fluorine 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.

  As a method of performing the RIE processing in the present invention with a winding type in-line apparatus, a method of applying a voltage to the cathode side (cooling drum) on which the PEN film is installed to form a planar type (FIG. 3), or a holo anode There is a method (FIG. 4) in which processing is performed using a plasma processing device.

  In FIG. 3, if a planar type process is performed, the PEN film 10 can be placed on the cathode 7 (cathode) side of the cooling drum 9, and processing by RIE using the plasma 8 can be performed by obtaining a high self-bias. (Figure 3). If the application electrode is installed on the opposite side of the cooling drum or guide roll, as is normally done with inline processing, the PEN film is installed on the anode (anode) side. At this time, since the PEN film cannot obtain a high self-bias, and only a so-called plasma etching is performed in which radicals act on the surface of the PEN film and only chemically react, the adhesion between the inorganic oxide layer and the PEN film is low. Until now.

  In FIG. 4, the holo anode / plasma processor has a hollow anode 11, and the area (Sa) of the anode 11 is Sa> Sc compared to the substrate area (Sc) as a counter electrode. Such a processor. By increasing the area of the anode 11, a large self-bias can be generated on the cathode (PEN film 12) serving 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 confinement effect of the plasma 13 can be further enhanced by the magnetic field generated from the magnetic electrode, and a high ion current density can be obtained with a large self-bias. In FIG. 4, reference numeral 14 denotes a guide roll, 15 denotes a gas introduction pipe, 16 denotes a matching box, and 17 denotes a shielding plate.

  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 inorganic oxide layer 2 will be described in detail.
The inorganic oxide layer 2 in the present invention is a layer made of an inorganic oxide such as aluminum oxide, silicon oxide, tin oxide, magnesium oxide, or a mixture thereof, and has transparency and a gas barrier such as oxygen and water vapor. Any layer having a property may be used. Among these, it is more preferable to use aluminum oxide, silicon oxide or a mixture thereof in consideration of resistance in a high temperature and high humidity environment. However, the inorganic oxide layer 2 of the present invention is not limited to the inorganic oxide described above, and any material that meets the above conditions can be used.

  The optimum condition of the thickness of the inorganic oxide layer 2 varies depending on the kind and configuration of the inorganic compound to be used, but generally it is 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 of laminating the inorganic oxide layer 2 on the PEN film 1, 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. It is preferable to use any one of an electron beam heating method, a resistance heating method, and an induction heating method as the heating means of the vacuum evaporation method, but considering 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. Further, in order to improve the adhesion between the inorganic oxide layer 2 and the PEN film 1 and the denseness of the inorganic oxide layer 2, it is also possible to perform deposition using a plasma assist method or an ion beam assist method. Further, in order to increase the transparency of the inorganic oxide layer 2, it is possible to use reactive vapor deposition in which various gases such as oxygen are blown during vapor deposition. It is preferable that the RIE treatment and the lamination of the inorganic oxide layer 2 be performed with the same film forming machine (in-line film forming machine), because productivity can be improved.

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

[Surface condition analysis method]
The measuring apparatus used was JPS-90MXV manufactured by JEOL Ltd., non-monochromated MgKα (1253.6 eV) was used as the X-ray source, and the output was measured at 100 W (10 kV-10 mA). For quantitative analysis, calculation was performed using a relative sensitivity factor of 2.28 for O1s and 1.00 for C1s. For the waveform separation analysis of the C1s waveform, a device-separated waveform separation software is used, and a mixed function of a Gaussian function and a Lorentz function is used. The CC bond peak is 285.0 eV, the CO bond peak is 286.6 eV, and COO. Waveform separation analysis was performed with a binding peak of 289.0 eV.

<Example 1>
One side of a 12 μm-thick PEN film was pretreated by reactive ion etching (RIE) using a holoanode plasma processor as a treatment method. At this time, a high frequency power source having a frequency of 13.56 MHz was used for the electrodes, and hydrogen gas was used for the processing gas. In XPS measurement, O / C was 0.30, C—O / C—C was 0.22, and COO / C—C was 0.22. On top of this, silicon oxide was deposited to a thickness of about 40 nm using a resistance heating method to produce a gas barrier laminate.

<Example 2>
O / C in the XPS measurement of the PEN film obtained by processing using oxygen gas as the processing gas is 0.36, C-O / C-C is 0.18, and COO / C-C is 0.18. A gas barrier laminate was produced in the same manner as in Example 1 except that.

<Example 3>
In the XPS measurement of the PEN film obtained by processing using argon / oxygen mixed gas as the processing gas, O / C is 0.34, C—O / C—C is 0.18, and COO / C—C is 0. A gas barrier laminate was produced in the same manner as in Example 1 except that it was .16.

<Example 4>
O / C in XPS measurement of PEN film obtained by processing using nitrogen gas as the processing gas is 0.30, C-O / C-C is 0.12, and COO / C-C is 0.15. A gas barrier laminate was produced in the same manner as in Example 1 except that.

<Example 5>
As a processing method, it is a planar type in which a voltage is applied from the cooling drum side, and pre-processing by RIE using plasma is performed, and O / O in XPS measurement of a PEN film obtained by processing using argon gas as a processing gas. A gas barrier laminate was produced in the same manner as in Example 1 except that C was 0.25, C—O / C—C was 0.13, and COO / C—C was 0.13.

<Comparative Example 1>
O / C in XPS measurement of PEN film obtained by using oxygen / nitrogen mixed gas as process gas is 0.46, C—O / C—C is 0.36, and COO / C—C is 0.38. A gas barrier laminate was produced in the same manner as in Example 1 except for the above.

<Comparative example 2>
In the XPS measurement of the PEN film obtained by corona treatment on a PEN film using a corona treatment apparatus, O / C is 0.44, C—O / C—C is 0.41, and COO / C—C is 0. A gas barrier laminate was produced in the same manner as in Example 1 except that it was .43.

On the gas barrier laminated films of Examples 1 to 5 and Comparative Examples 1 and 2, solutions A and B shown below were mixed in a mixing ratio (wt%) to 6/4.
Liquid A: A hydrolyzed solution having a solid content of 3 wt% (in terms of SiO ₂ ) obtained by adding 89.6 g of hydrochloric acid (0.1N) to 10.4 g of tetraethoxysilane and stirring for 30 minutes for hydrolysis.
Liquid B: 3 wt% water / isopropyl alcohol solution of polyvinyl alcohol (90:10 by weight ratio of water: isopropyl alcohol).
This solution was applied and dried by a gravure coating method to form a composite coating layer having a thickness of 0.5 μm.

Furthermore, a laminate sample of polyvinyl fluoride (50 μm) / gas barrier laminate film / polyvinyl fluoride (50 μm) was prepared by dry lamination using a two-component curable polyurethane adhesive. A cross-sectional structure of the laminated sample is shown in FIG.
<Evaluation>
The laminate strength between the polyvinyl fluoride film / gas barrier laminate film at the portion indicated by arrow a in the laminate sample was measured using a Tensilon universal tester RTC-1250 (Orientec Corp.) (conforms to JIS Z1707). However, before the measurement, the peel strength was measured after the sample was left in a high temperature and high humidity environment of a pressure cooker test (105 ° C. 100%) for 60 hours. The results are shown in Table 1.

  Therefore, the element ratio (O / C) is 0.20 to 0.40, the functional group ratio (C—O / C—C) obtained from the analysis of the C1s waveform is 0.10 to 0.25, (COO / It was shown that the peel strengths of Comparative Examples 1 and 2 except that CC) was adjusted to 0.10 to 0.25 were low.

  As described above, the gas barrier laminate of the present invention provides a gas barrier laminate in which the adhesion between the PEN film and the inorganic oxide layer is high and the adhesion between the PEN film and the inorganic oxide layer does not deteriorate even in a high temperature and high humidity environment. can do.

  The gas barrier laminate of the present invention is particularly useful as a gas barrier laminate for a backside protective sheet that is suitable for protecting module cells and wiring of solar cells and has excellent durability.

It is sectional drawing of an example of the gas barrier laminated body of this invention. It is an XPSC1s waveform isolation | separation spectrum figure of an unprocessed PEN surface. It is a schematic diagram for demonstrating a planar type plasma processing. It is a schematic diagram for demonstrating the plasma processing using a holo anode plasma processing device. It is a figure which shows the cross-section of the laminated sample used in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 PEN film 2 Inorganic oxide layer 3 Pretreatment layer 4 by RIE CC bond peak 5 CO bond peak 6 COO bond peak 7 Cathode 8 Plasma 9 Cooling drum 10 PEN film 11 Anode 12 PEN film 13 Plasma 14 Guide roll 15 Gas introduction pipe 16 Matching box 17 Shield plate

Claims (7)

A gas barrier laminate comprising an inorganic oxide layer laminated on at least one surface of a polyethylene naphthalate film,
Reactive ion etching (RIE) treatment using plasma is performed on at least the surface of the polyethylene naphthalate film on which the inorganic oxide layer is provided,
When X-ray photoelectron spectroscopic measurement of the surface subjected to the RIE treatment (measurement conditions: X-ray source MgKα, X-ray output 100 W) is performed, the atomic ratio (O / C) of the oxygen element to the carbon element is 0.20. A gas barrier laminate characterized by being in the range of ~ 0.40.   When X-ray photoelectron spectroscopy measurement (measurement condition: X-ray source MgKα, X-ray output 100 W) of the surface subjected to the RIE treatment is performed, the functional group ratio (C—O / C—C) obtained from the analysis of the C1s waveform ) Is in the range of 0.10 to 0.25. The gas barrier laminate according to claim 1, wherein   When the X-ray photoelectron spectroscopic measurement (measurement condition: X-ray source MgKα, X-ray output 100 W) of the surface subjected to the RIE treatment is performed, the functional group ratio (COO / C-C) obtained from the analysis of the C1s waveform is It is in the range of 0.10-0.25, The gas barrier laminated body of Claim 1 or 2 characterized by the above-mentioned.   The RIE process is a planar type plasma process in which a substrate is placed on the cathode side to which a voltage is directly applied, or a plasma process using a holo anode plasma processor. The gas barrier laminate according to any one of the above.   5. The process according to claim 1, wherein the RIE process is a process performed one or more times using one kind of gas of argon, nitrogen, oxygen, and hydrogen, or a mixed gas thereof. A gas barrier laminate as described in 1.   The gas barrier laminate according to any one of claims 1 to 5, wherein the inorganic oxide layer is made of aluminum oxide, silicon oxide, or a mixture thereof.   The gas barrier laminate according to any one of claims 1 to 6, wherein the RIE treatment and the lamination of the inorganic oxide layer are performed by the same film forming machine.

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