JP5696085B2 - Gas barrier laminate and method for producing the same - Google Patents

Description

  The present invention relates to a gas barrier laminate using a polyethylene terephthalate resin film substrate and a method for producing the same.

  In recent years, packaging materials used for packaging foods, non-foods, pharmaceuticals, and the like are required to suppress the deterioration of contents and retain their functions and properties. For this reason, these packaging materials need to have a function of preventing permeation of oxygen, water vapor, and other gases that alter the contents. As such a packaging material, a gas barrier laminate is known. In recent years, gas barrier laminates have come to be used as industrial material applications typified by back surface protection sheets that are members of solar cell modules.

  Conventionally, a metal foil such as an aluminum foil that is less affected by temperature and humidity has been generally used as the gas barrier layer of the back surface protection sheet for solar cell modules. However, the metal foil has drawbacks such as poor insulation with solar cell and wiring due to aging.

  As a material for overcoming such a problem of insulation failure, a deposited film obtained by depositing silicon oxide on a fluororesin film has been proposed (see, for example, Patent Document 1). This deposited film has an effect of improving the adhesion of laminated films in addition to gas barrier properties such as oxygen and water vapor, and is expected as a material having insulating properties and transparency that cannot be obtained with a metal foil.

JP-A-10-308521

  However, when a conventional gas barrier laminate in which a silicon oxide thin film is laminated on a substrate made of a resin film, the adhesion between the substrate and the silicon oxide thin film decreases when exposed to a high temperature and high humidity environment for a long time. There is a problem that there is. Although it is possible to suppress such deterioration by applying an anchor coat to the substrate surface, it leads to an increase in the number of steps in the production of the gas barrier laminate. In addition, since the site of occurrence of peeling deterioration is the substrate surface layer, the deterioration cannot be sufficiently suppressed.

  An object of this invention is to provide the gas barrier laminated body which can maintain the adhesiveness of the silicon oxide thin film with respect to a polyethylene terephthalate resin film base material also in a hot and humid environment, and its manufacturing method.

According to a first aspect of the present invention, a substrate comprising a polyethylene terephthalate resin film (hereinafter abbreviated as PET film) and a silicon oxide thin film laminated on at least one surface of the substrate are provided, and the PET film is The molecular chain orientation angle measured by the phase difference measurement method is 50 ° to 90 ° or −50 ° to −90 ° with respect to the MD direction (Machine Direction = flow direction during film production), and the silicon oxide thin film is A gas barrier laminate is provided in which the ratio of oxygen to silicon (O / Si) calculated by X-ray photoelectron spectroscopy is in the range of 1.8 to 2.0.

According to the second aspect of the present invention, a PET film in which the molecular chain orientation angle measured by the phase difference measurement method is 50 ° to 90 ° or −50 ° to −90 ° with respect to the MD direction is selected as a substrate. And a silicon oxide thin film having a ratio of oxygen to silicon (O / Si) calculated by X-ray photoelectron spectroscopy in the range of 1.8 to 2.0 on at least one surface of the substrate. And a step of laminating. A method for producing a gas barrier laminate is provided.
“Lamination on one surface of the substrate” means that the silicon oxide thin film 2 is directly laminated on the surface of the PET film substrate 1 without any anchor coat layer or base layer as shown in FIG. Means that.

  ADVANTAGE OF THE INVENTION According to this invention, the gas barrier laminated body which can maintain the adhesiveness of the silicon oxide thin film with respect to a PET film base material also in a hot and humid environment, and its manufacturing method are provided.

FIG. 1 is a schematic cross-sectional view of a gas barrier laminate according to the first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a gas barrier laminate according to another embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of a gas barrier laminate according to another embodiment of the present invention. FIG. 4 is a schematic view showing a form in which reactive ion etching (RIE) is performed in a planar plasma processing apparatus. FIG. 5 is a schematic view showing a form in which reactive ion etching (RIE) is performed in a holo anode plasma processing apparatus. FIG. 6 is an explanatory diagram showing the definition of the orientation angle of the PET film substrate.

Hereinafter, a gas barrier laminate and a manufacturing method thereof according to an embodiment of the present invention will be described in detail.
(First embodiment)
The gas barrier laminate according to the first embodiment includes a base material made of a PET film and a silicon oxide thin film laminated on at least one surface of the base material. The PET film substrate has a molecular chain orientation angle of 50 ° to 90 ° or −50 ° to −90 ° with respect to the MD direction as measured by retardation measurement.

  Here, as shown in FIG. 6, the orientation angle is defined as + when the molecular direction is aligned with the MD direction being 0 ° and tilted to the left, and − when the molecular chain is aligned with the tilt to the right. . In the figure, TD is Transvers Direction and indicates the width direction of the film.

  The orientation angle in the MD direction can be determined using a technique such as a phase difference measurement method using visible light, a molecular orientation measurement method using a microwave, or the like. However, in the case of a molecular orientation measurement method using a microwave, the measurement value varies by the measurer. On the other hand, the phase difference measurement method can stably measure regardless of the measurer, and there is little variation of the measurer. In addition, the orientation angle can be accurately measured. For this reason, it is good to employ | adopt a phase difference measuring method for the measurement of the orientation angle with respect to MD direction.

  As a result of various studies on the decrease in adhesion in conventional gas barrier laminates in which a silicon oxide thin film is laminated on a substrate made of a resin film, the present inventor has found a decrease in cohesive force on the film substrate surface on which the silicon oxide thin film is laminated. Has been found to cause a decrease in adhesion to the substrate.

Based on such investigation results, the present inventor conducted further diligent research on the cohesive force of the substrate surface made of PET film forming the silicon oxide thin film. As a result, the orientation angle of the substrate made of PET film with respect to the MD direction is related. I found out.

  That is, usually, a PET film is biaxially stretched and then held at an appropriate heat setting temperature, and adjusted so that molecules are aligned horizontally or vertically with respect to the MD direction of the film surface. The orientation angle with respect to the MD direction is determined by the orientation angle of the molecules. A silicon oxide thin film laminated on a PET film having an orientation angle with respect to the MD direction measured by the phase difference measurement method in the range of 50 ° to 90 ° or −50 ° to −90 ° as a substrate. The adhesion of is improved. Moreover, such characteristics can be maintained even in a high temperature and high humidity environment. This is a knowledge obtained for the first time by the present inventors.

  Hereinafter, the gas barrier laminate according to the first embodiment of the present invention will be described in detail with reference to FIG. FIG. 1 is a schematic cross-sectional view showing the gas barrier laminate of the first embodiment. The gas barrier laminate (10) has a structure in which a silicon oxide thin film (2) is laminated on a PET film substrate (1).

  In the PET film substrate (1), the orientation angle with respect to the MD direction measured by the phase difference measurement method is defined in the range of 50 ° to 90 ° or −50 ° to −90 °. The PET film substrate (1) is preferably transparent so as not to impair the transparency of the silicon oxide thin film (2).

  As the PET film substrate (1), a stretched one having high mechanical strength and excellent dimensional stability is used. In the first embodiment, the PET film substrate (1) has undergone biaxial stretching and heat setting in order to ensure an orientation angle with respect to the MD direction of 50 ° to 90 ° or −50 ° to −90 °. Is used. The orientation angle can be controlled by appropriately selecting the conditions of biaxial stretching and heat setting. For example, the orientation angle of the PET film substrate (1) can be selected within a desired range by using the central portion with respect to the width direction after biaxial stretching.

  The thickness of the PET film substrate (1) is not particularly limited, but if it is too thin, wrinkles may occur or the film may break when the silicon oxide thin film (2) is formed by a winding device. On the other hand, if it is too thick, the flexibility of the film is lowered, which may make it difficult to process with a winding device. A base material having a thickness of 3 to 200 μm can form a silicon oxide thin film with a winding device without causing any inconvenience. A more preferable thickness of the PET film substrate (1) is 6 to 50 μm.

  The silicon oxide constituting the silicon oxide thin film (2) preferably has a specific value of the ratio of oxygen to silicon (O / Si ratio) calculated by the XPS measurement method. If the O / Si ratio is too small, sufficient barrier properties cannot be ensured, and the film is colored and the transparency is impaired, and film defects such as cracks are likely to occur. As a result, the barrier property of the gas barrier laminate (10) having the silicon oxide thin film (2) is lowered, and the adhesion between the silicon oxide thin film (2) and the PET film substrate (1) may be lowered. . The silicon oxide thin film (2) having an O / Si ratio in the range of 1.6 to 2.0 is transparent and exhibits high adhesion to the PET film substrate (1).

  The silicon oxide thin film (2) preferably has an appropriate thickness. If the thickness of the silicon oxide thin film (2) is too thin, a uniform film cannot be formed, and it will be difficult to sufficiently function as a gas barrier material. On the other hand, if the thickness of the silicon oxide thin film (2) is too thick, flexibility cannot be maintained due to residual stress, and cracks may occur due to external factors after film formation. The silicon oxide thin film (2) specified to have a thickness in the range of 5 to 300 nm exhibits a uniform thickness and flexibility suitable as a gas barrier material. A more preferable thickness of the silicon oxide thin film (2) is 10 to 100 nm.

  The silicon oxide thin film (2) may be deposited using a plasma assist method or an ion beam assist method in order to improve the denseness and the adhesion to the PET film substrate (1). Further, by performing vapor deposition while blowing various gases such as oxygen (reactive vapor deposition), the transparency of the deposited silicon oxide thin film can be further enhanced.

  As shown in FIGS. 2 and 3, the gas barrier laminate according to the first embodiment forms an anchor coat layer (3a) and an underlayer (3b) on the surface of a PET film substrate (1), and silicon oxide is formed thereon. You may make it the structure which provided the thin film (2). The base layer (3b) can be formed by subjecting the surface of the PET film substrate (1) to pretreatment by reactive ion etching (RIE).

  The anchor coat layer (3a) can be formed by applying an anchor coat agent to the surface of the PET film substrate (1) and drying it. The anchor coat layer (3a) has an effect of further improving the adhesion between the PET film substrate (1) and the silicon oxide thin film (2).

  Anchor coating agents include, for example, solvent-soluble or water-soluble polyester resins, isocyanate resins, urethane resins, acrylic resins, polyvinyl alcohol resins, ethylene vinyl alcohol resins, vinyl modified resins, epoxy resins, oxazoline group-containing resins, modified styrene resins, It is selected from a modified silicone resin or an alkyl titanate, and these can be used alone or in combination of two or more.

The anchor coat layer (3a) can usually have a thickness of about 5 nm to 5 μm. The anchor coat layer having such a thickness can be formed on the substrate surface with a uniform film thickness in which internal stress is suppressed. A more preferable thickness of the anchor coat layer (3a) is 10 nm to 1 μm.
In order to improve the applicability and adhesion of the anchor coat layer (3a), the substrate surface may be subjected to a discharge treatment prior to the anchor coat.

  On the other hand, plasma is used when RIE processing is performed on the surface of the base material in the formation of the underlayer (3b). A chemical effect of imparting a functional group to the surface of the substrate is obtained by radicals and ions generated in the plasma. Further, the physical effect of removing the surface impurities by ion etching and increasing the surface roughness can be obtained. As a result, the adhesion between the PET film substrate (1) and the silicon oxide thin film (2) is further improved, and the two are not peeled even in a high temperature and high humidity environment.

  The processing by RIE can be performed using a winding-type in-line apparatus. As the winding-type inline apparatus, a planar type processing apparatus that applies a voltage to a cooling drum on which a base material is installed can be used. For example, in the method of RIE processing a substrate with the planar processing apparatus shown in FIG. 4, an electrode (cathode) (4) is arranged inside the processing roll (6), and the PET film substrate (1) is processed into a processing roll ( While carrying along 6), the ions (5) in the plasma are allowed to act on the surface of the PET film substrate (1) to carry out the RIE treatment. According to such a method, the PET film substrate (1) can be placed on the cathode (cathode) side, and processing by RIE can be performed by obtaining a high self-bias.

The RIE process can also be performed using a holo anode plasma processing apparatus. For example, the holo anode plasma processing apparatus shown in FIG. 5 includes a processing roll (6) as an anode. The cathode (4) and the shielding plates (10) arranged at both ends thereof are arranged outside the processing roll (6) so as to face the processing roll (6). The cathode (4) has a box shape with an opening on the processing roll (6) side. The shielding plate (7) has a curved surface shape along the processing roll (6). The gas introduction nozzle (8) is disposed above the cathode (4) and introduces gas into the gap between the processing roll (6), the cathode (4), and the shielding plate (7). The matching box (9) is arranged on the back surface of the cathode (4).

  In order to carry out RIE processing of the base material with such a holo anode plasma processing apparatus, a voltage is applied from the matching box (9) to the cathode (4) while transporting the PET film base material (1) along the processing roll (6). To generate a plasma between the treatment roll (6) into which the gas is introduced, the cathode (4) and the shielding plate (7), and attract the radicals in the plasma to the treatment roll (6) side which is the anode. Thus, radicals are allowed to act on the surface of the PET film substrate (1). This radical action is mainly a chemical reaction, and mainly plasma etching is performed, and the adhesion between the substrate and the silicon oxide thin film cannot be sufficiently improved.

  Therefore, in the holo anode / plasma processing apparatus shown in FIG. 5, the area (Sa) of the processing roll (6) as the anode is larger than the area (Sc) of the PET film substrate (1) as a counter electrode (Sa> With the Sc) configuration, a large amount of self-bias can be generated on the substrate. Due to this large self-bias, in addition to the above-described chemical reaction, a sputtering action (physical action) that attracts ions (5) in the plasma to the PET film base (1) works. Therefore, the PET film base after the RIE treatment (1) When the silicon oxide thin film (2) is formed on the surface, the adhesion between them can be improved.

  In the RIE process, it is preferable to incorporate a magnet into the holo anode electrode to form a magnetic assist holo anode. This makes it possible to perform more powerful and stable plasma surface treatment at high speed. 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.

  As the gas species for performing the pretreatment by RIE, for example, argon, oxygen, nitrogen, and hydrogen can be used. These gases may be used alone or in combination of two or more.

  In the RIE process, two or more processing apparatuses can be used for continuous processing. At this time, it is not necessary to use the same two or more processing apparatuses. For example, it is possible to treat a substrate with a planar type processing apparatus, and subsequently perform processing using a holo anode plasma processing apparatus.

  In the gas barrier laminate according to the first embodiment, any of the structures shown in FIGS. 1 to 3 described above may further include another layer. For example, a silicon oxide thin film may be formed on the other surface of the PET film substrate (1).

  Further, an overcoat layer may be formed on the silicon oxide thin film (2) to improve protection and adhesion. Materials for the overcoat layer include, for example, solvent-soluble or water-soluble polyester resins, isocyanate resins, urethane resins, acrylic resins, polyvinyl alcohol resins, ethylene / vinyl alcohol copolymer (EVOH) resins, vinyl-modified resins, and epoxy resins. , An oxazoline group-containing resin, a modified styrene resin, a modified silicon resin, an alkyl titanate, and the like. An overcoat layer can be comprised by the single layer using these materials, or two or more types of lamination | stacking.

A filler can be added to the overcoat layer to improve barrier properties, wear properties, slip properties, and the like. Examples of the filler include silica sol, alumina sol, particulate inorganic filler, and layered inorganic filler. These can be used alone or in combination of two or more. The overcoat layer is preferably formed by adding a filler to the aforementioned resin and polymerizing or condensing it.

  When the silicon oxide thin film (2) is provided only on one side of the PET film substrate (1), a layer containing a known additive such as an antistatic agent, an ultraviolet absorber, a plasticizer, etc. is provided on the other side. Also good.

  The gas barrier laminate according to the embodiment can be laminated with another film in consideration of suitability as an industrial material or a packaging material. As this film, for example, a polyester film such as a PET film, a fluorine-based resin film such as a polyvinyl fluoride film or a polyfluorinated divinyl, and the like can be used. Furthermore, resin films other than these can be laminated.

(Second Embodiment)
In the method for producing a gas barrier laminate according to the second embodiment, first, the orientation angle of a molecular chain measured from a PET film by a phase difference measurement method is 50 ° to 90 ° or −50 ° to −50 ° with respect to the MD direction. A PET film having a range of 90 ° is selected and used as a substrate. The phase difference measurement can be performed using a phase difference measuring apparatus of an example described later.

  Next, a silicon oxide thin film (2) is laminated on the surface of the PET film substrate (1) to produce a gas barrier laminate. For the lamination of the silicon oxide thin film (2), for example, a vacuum deposition method, a sputtering method, an ion plating method, a plasma vapor phase growth method, or the like can be employed. In view of productivity, the vacuum deposition method is preferable.

  The heating method in the vacuum deposition method is not particularly limited, and for example, an electron beam heating method, a resistance heating method, an induction heating method, or the like can be adopted. The electron beam heating method or the resistance heating method is more preferable because the selectivity of the evaporation material can be expanded.

  In the second embodiment, prior to laminating the silicon oxide thin film (2) on the substrate surface, an anchor coat layer (3a) or a base layer (3b) by RIE treatment is formed as in the first embodiment. It is acceptable.

  In the second embodiment, it is allowed to form an overcoat layer on the silicon oxide thin film (2) as in the first embodiment. In the second embodiment, a silicon oxide thin film can be laminated on the other surface of the PET film substrate (1).

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

  Eight types of PET film substrates having a thickness of 12 μm were prepared, and the phase difference was measured to determine the orientation angle. That is, the phase difference was measured at an incident angle of 0 ° to 50 ° (10 ° pitch) with respect to an area of 40 mm × 40 mm of the PET film using a phase difference measuring device (manufactured by Oji Scientific Instruments, KOBRA-WR). Table 1 below shows the measured orientation angles of the eight types of PET film substrates with respect to the MD direction.

Next, eight types of gas barrier laminate samples were produced by depositing silicon oxide on one surface of each PET film substrate by electron beam heating and laminating a thin film having a thickness of 30 nm.
The O / Si ratio in the silicon oxide thin film in each obtained sample was determined by X-ray photoelectron spectroscopy (XPS). The measuring device is an X-ray photoelectron spectroscopic analyzer (manufactured by JEOL Ltd., JPS-90MXV). As the X-ray source, non-monochromated MgKα (1253.6 eV) was used, and measurement was performed with an X-ray output of 100 W (10 kV-10 mA). Relative sensitivity factors of 2.28 for O1s and 0.9 for Si2p were used in the quantitative analysis to determine the O / Si ratio. Table 1 shows the O / Si ratios of the eight types of samples.

Further, the peel strength of each sample was examined by the following method.
A nylon film (ONy) and polypropylene (CPP) were adhered to the gas barrier laminate sample using a urethane-based adhesive to form a laminate structure. Peeling was made at the interface between the adhered PET film and the silicon oxide thin film, and the peel strength was measured. The tensile tester measured the peeling strength when peeling at 180 degrees using Orientec Corp. Tensilon RTC-1250. The results are shown in Table 1 below. In the evaluation of Table 1, the peel strength was determined to be 2N / 15 mm or more as acceptable (◯), and less than 2N / 15 mm as unacceptable (x).

  As is clear from Table 1, in Comparative Example 1 using a PET film having an orientation angle of 45.2 ° as a substrate, the peel strength is 0.5 N / 15 mm, which is out of the acceptable range. Similarly, Comparative Example 2 using a PET film having an orientation angle of 38.6 ° as a base material has a peel strength of 0.3 N / 15 mm, which is out of the acceptable range. Furthermore, in Comparative Example 3 using a PET film having an orientation angle of −28.5 ° as 1.535 as a base material, the peel strength is 0.2 N / 15 mm, which is out of the acceptable range. Thus, in Comparative Examples 1 to 3 using a PET film having an orientation angle of 0 ° to 50 ° or 0 to −50 ° as a base material, a gas barrier laminate having desired adhesion and barrier properties cannot be obtained. I understand that.

  In contrast, in the samples of Examples 1 to 5 using a PET film having an orientation angle measured by the phase difference method of 50 to 90 ° or −50 to −90 ° as a base material, the peel strength is 2.2 N. / 15 mm or more, and the maximum is 3.2 N / 15 mm, and it can be seen that high adhesion can be imparted between the substrate and the silicon oxide thin film.

  As described above, a gas barrier laminate can be provided in which the adhesion is not easily deteriorated even in a high-temperature and high-humidity environment by using the PET film in which the orientation angle with respect to the MD direction is defined within a predetermined range by the retardation method.

  INDUSTRIAL APPLICABILITY The present invention can provide a gas barrier laminate that is used as a packaging material for foods, precision electronic components, and pharmaceuticals, and can be used for industrial materials such as a back surface protection sheet that is a member of a solar cell module, and a method for manufacturing the same.

DESCRIPTION OF SYMBOLS 1 ... PET film base material 2 ... Silicon oxide thin film 3a ... Anchor coat layer 3b ... Underlayer 4 ... Electrode (cathode)
5 ... Plasma 6 ... Processing roll 7 ... Shield plate 8 ... Gas inlet 9 ... Matching box 10 ... Gas barrier laminate 20 ... Gas barrier laminate

Claims (3)

A substrate comprising a polyethylene terephthalate resin film and a silicon oxide thin film laminated on at least one surface of the substrate, and the polyethylene terephthalate resin film has an orientation angle of molecular chains measured by a phase difference measurement method The silicon oxide thin film has a ratio of oxygen to silicon (O / Si) calculated by X-ray photoelectron spectroscopy in the range of 50 ° to 90 ° or −50 ° to −90 ° with respect to the MD direction. It is in the range of 1.8-2.0, The gas barrier laminated body characterized by the above-mentioned.   The gas barrier laminate according to claim 1, wherein the silicon oxide thin film has a thickness of 5 to 300 nm. Selecting a polyethylene terephthalate resin film having an orientation angle of 50 ° to 90 ° or −50 ° to −90 ° with respect to the MD direction as a substrate, and at least one of the substrates; And a step of laminating a silicon oxide thin film having an oxygen to silicon ratio (O / Si) calculated by X-ray photoelectron spectroscopy in the range of 1.8 to 2.0 on the surface of A method for producing a gas barrier laminate.

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