JP2008049576A - Gas barrier laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat treatment-resistant gas-barrier laminate which keeps original gas-barrier properties without degrading adhesion even when subjected to heat treatment including heating sterilization such as boiling sterilization or retort sterilization, cooking, etc. <P>SOLUTION: In the gas-barrier laminate, a vapor deposition film layer made of at least an inorganic oxide is laminated on the polyethylene terephthalate substrate. A pretreatment part is formed on at least one side of the substrate by pretreatment using discharge treatment. The distance between the peaks of C-C and C-O bonds measured by an X-ray photoelectron spectroscopic method of the treatment part is 1.65-1.76 eV. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is a film-like gas barrier laminate suitably used for packaging foods, pharmaceuticals and the like, and particularly has adhesiveness even when heat treatment such as boil sterilization or retort sterilization or heat treatment is performed. The present invention relates to a gas barrier laminate having heat treatment resistance that does not deteriorate and does not deteriorate the initial gas barrier property that it had before heat treatment.

  In recent years, packaging materials used for packaging foods, pharmaceuticals, etc., are made of oxygen, water vapor, or other gas that alters the contents that penetrates the packaging materials in order to suppress the alteration of the contents and retain their functions and properties. It is necessary to prevent the influence, and it is required to have a gas barrier property or the like for blocking these gases. Therefore, conventionally, a packaging material using a metal foil such as aluminum, which is less affected by temperature, humidity, etc., as a gas barrier layer has been generally used.

  However, packaging materials using metal foils such as aluminum are less affected by temperature, humidity, etc., and show high gas barrier properties. However, the contents cannot be confirmed through them, and when discarded after use However, it has problems such as having to treat it as an incombustible material and not being able to use a metal detector for inspection.

  Therefore, in order to overcome these drawbacks, there is a packaging material (deposited film) in which a deposited thin film layer of an inorganic oxide such as silicon oxide or aluminum oxide is formed on a plastic film by thin film forming means such as vacuum deposition or sputtering. It has been proposed (see, for example, Patent Documents 1 and 2). These vapor-deposited films are known to have transparency and gas barrier properties against oxygen, water vapor, etc., and cannot be obtained with packaging materials using metal foils, etc., and have both transparency and gas barrier properties. Is widely used.

  However, in such packaging materials, when an inorganic oxide is deposited on a plastic film that has not been pretreated, the adhesiveness between the plastic film and the deposited thin film layer is weak, so boil sterilization, retort sterilization, etc. When heat treatment is performed by heat sterilization or retort cooking, delamination is often caused. In addition, there is a problem that the gas barrier property is deteriorated due to a decrease in adhesion.

In order to solve such problems, the plastic film surface is subjected to pretreatment using chemicals, flame, plasma, etc., and the adhesion with the deposited thin film layer of inorganic oxide formed thereon is improved. Various attempts have been made to improve adhesion and post-processing suitability.
U.S. Pat. No. 3,442,686 Japanese Patent Publication No.63-28017

  The present invention has been made in view of the above situation, and improves the adhesion between a polyethylene terephthalate substrate made of a polyethylene terephthalate film or sheet and a vapor-deposited thin film layer made of an inorganic oxide, It aims at providing the gas-barrier laminated body which does not generate | occur | produce a delamination even if heat processing, such as heat sterilization, are performed.

  In order to achieve the above-described problems, the invention according to claim 1 is a gas barrier laminate in which a vapor-deposited thin film layer made of at least an inorganic oxide is laminated on a polyethylene terephthalate substrate, the inorganic oxide At least one surface of the substrate on which the vapor-deposited thin film layer is laminated is formed with a pretreatment portion by a pretreatment utilizing a discharge treatment, and C of the treatment portion measured by X-ray photoelectron spectroscopy. The gas barrier laminate is characterized in that the peak-to-peak distance between the —C bond peak and the C—O bond peak is 1.65 to 1.76 eV.

  The invention described in claim 2 is characterized in that, in the gas barrier laminate according to claim 1, the thickness of the vapor-deposited thin film layer made of the inorganic oxide is in the range of 10 to 100 nm.

  Furthermore, the invention according to claim 3 is the gas barrier laminate according to claim 1 or 2, wherein the inorganic oxide is aluminum oxide, silicon oxide, magnesium oxide, tin oxide, indium oxide, zinc oxide, oxidation It is characterized by being either tungsten or a mixture thereof.

  Furthermore, the invention according to claim 4 is the gas barrier laminate according to any one of claims 1 to 3, wherein the pretreatment part is formed by plasma treatment using discharge treatment. Features.

  Furthermore, the invention according to claim 5 is the gas barrier laminate according to claim 4, wherein the pretreatment section uses one kind of gas of argon, nitrogen, oxygen, hydrogen, or a mixed gas thereof. It is characterized by being formed by one or a plurality of continuous plasma treatments.

  According to the present invention, even when heat treatment such as retort cooking or heat sterilization treatment is performed, good adhesion can be maintained, and the gas barrier properties that the laminate initially had do not deteriorate.

  Embodiments of the present invention will be described below.

  FIG. 1 is an explanatory view showing an example of a schematic cross-sectional configuration of a gas barrier laminate of the present invention. The illustrated gas barrier laminate is obtained by laminating a vapor deposition thin film layer 2 made of an inorganic oxide on a polyethylene terephthalate (PET) substrate 1.

  The base material 1 has a pretreatment portion 3 formed on the surface by pretreatment utilizing discharge treatment, and the surface state of the Cls waveform obtained by measurement by X-ray photoelectron spectroscopy (XPS measurement). The distance between the C—C bond peak and the C—O bond peak by peak separation analysis is set to be in the range of 1.65 to 1.76 eV.

  When the surface of a so-called untreated PET film that has not been subjected to pretreatment such as discharge treatment on the surface is subjected to peak separation analysis based on a Cls waveform obtained by measurement by X-ray photoelectron spectroscopy (XPS measurement), As shown in FIG. 2, the C1s waveform is separated into a C—C bond peak 4, a C—O bond peak 5, and a COO bond peak 6.

The inventors of the present invention performed discharge treatment on the surface of an untreated PET film having such a surface state, and the surface state was found to be a C—C bond peak and C— by peak separation analysis of a Cls waveform obtained by XPS measurement. By forming the pretreatment part 3 such that the peak-to-peak distance of the O bond peak is in the range of 1.65 to 1.76 eV, the vapor deposition thin film layer 2 made of an inorganic oxide laminated thereon is formed. It has been found that the adhesion can be made very strong, and even if heat treatment such as retort cooking, retort sterilization, and heat sterilization is added, the strong adhesion does not deteriorate.

  That is, in the C1s waveform obtained by XPS measurement on the surface of the untreated PET film, generally, the C—C bond derived from the PET molecule is 285.0 eV, the C—O bond is 286.6 eV, and the COO bond is 288.9 eV. A peak appears in the binding energy value of. Among these peaks, the distance between peaks of the C—C bond peak and the C—O bond peak (in the above case, 1.60) varies depending on the crystallinity and molecular weight of the outermost surface of the PET film. The gas barrier laminate obtained by laminating a vapor-deposited thin film layer made of an inorganic oxide on a PET film having a surface state with a peak-to-peak distance of less than 1.65 eV or more than 1.76 eV is subjected to heat treatment. In addition, the adhesiveness at the interface is lowered and peeling is likely to occur, and the gas barrier property possessed before the treatment is deteriorated.

  On the other hand, the surface condition of the surface of the PET film is determined by applying the pretreatment using the discharge treatment, and the distance between the C—C bond peak and the C—O bond peak of the C1s waveform related to the XPS measurement is determined. When it is set to be 1.65 to 1.76 eV, the adhesion with the deposited thin film layer made of an inorganic oxide is increased, and even if heat treatment is performed, peeling occurs very much. It becomes difficult, and it becomes possible to maintain the high gas barrier property originally possessed by the laminate.

  As the base material 1, a PET film, a PET sheet, and a film-like laminated base material in which a surface layer made of PET is laminated on the surface can be used. It is preferable to use a biaxially stretched PET film.

  In addition, known additives such as antistatic agents, ultraviolet absorbers, plasticizers, lubricants and the like may be appropriately added to the substrate 1, but the surface state thereof is XPS as described above. The distance between the C—C bond peak and the C—O bond peak of the C1s waveform related to the measurement needs to be 1.65 to 1.76 eV.

  The thickness of the substrate 1 is not particularly limited, and may be of a single layer structure or a multilayer structure in consideration of suitability as a packaging material. In consideration of the use as a packaging material, when considering the workability in the case of further laminating a primer layer and a gas barrier film layer, a material having a thickness in the range of 3 to 200 μm is preferable. More preferably, the thickness is 6 to 30 μm.

  In order to set the surface state of the substrate 1 so that the distance between the C—C bond peak and the C—O bond peak according to XPS measurement is 1.65 to 1.76 eV, the surface of the PET film is subjected to a discharge treatment. The pre-processing using can be performed. By performing this pretreatment, the distance between the peak of the C—C bond peak and the C—O bond peak is controlled within a predetermined range using the generated radicals and ions, and the substrate 1 and the inorganic oxide are formed. Adhesion with the vapor deposition thin film layer 2 can be strengthened, and even if heat treatment such as retort cooking or heat sterilization is performed, it becomes possible to prevent the occurrence of cracks and peeling in the vapor deposition thin film layer, The gas barrier property can be maintained.

  Examples of the gas species for performing the pretreatment by the above-described discharge treatment include argon, oxygen, nitrogen, and hydrogen. These gases may be used alone or in combination of two or more. Further, the pretreatment may be performed not only using one discharge processing machine but also continuously using two or more processing machines. It is not always necessary to use the same processing machine at this time.

  Next, the vapor deposition thin film layer 2 made of an inorganic oxide will be described in detail. The vapor-deposited thin film layer 2 made of an inorganic oxide is formed from a vapor-deposited film layer of an inorganic oxide such as aluminum oxide, silicon oxide, tin oxide, indium oxide, indium oxide, magnesium oxide, zinc oxide, tungsten oxide, or a mixture thereof. It is a layer having a gas barrier property against oxygen, water vapor and the like. Of these, those made of aluminum oxide or silicon oxide are more preferable in view of giving better heat treatment resistance.

  In general, the thickness of the deposited thin film layer 2 is desirably in the range of about 5 to 300 nm. Specific values can be appropriately selected according to the use, the layer structure of the laminate, and the like. However, when the layer thickness is less than 5 nm, it is difficult to obtain a uniform thin film layer, and the function as a gas barrier material may not be sufficiently achieved. Further, when the layer thickness exceeds 300 nm, it is difficult to maintain flexibility in the thin film layer, and it is not preferable because the thin film layer may be cracked by being bent or pulled after film formation. More preferably, it is in the range of 10 to 150 nm.

  As a method of forming the vapor deposition thin film layer 2 made of the inorganic oxide on the substrate 1, a thin film formation method such as a vacuum vapor deposition method, a sputtering method, an ion plating method, or a plasma vapor deposition method (CVD) is used. Can do. However, in view of productivity, the vacuum deposition method is most preferable at present. As a 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 the electron beam heating method should be used in consideration of the wide range of selectivity of the evaporation material. Is preferred. Moreover, in order to improve the adhesiveness of the vapor deposition thin film layer 2 and the base material 1 and the denseness of the vapor deposition thin film layer, it is also possible to form a film using a plasma assist method or an ion beam assist method. Further, in order to increase the transparency of the deposited thin film, it is possible to use reactive deposition in which various gases such as oxygen are blown during the deposition.

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

  A pretreatment using plasma treatment was performed on one surface of a double-side untreated PET film having a thickness of 12 μm using a plasma treatment machine to form a pretreatment portion. At this time, a high frequency power source with a frequency of 13.56 MHz was used for the electrodes, and a mixed gas of nitrogen and oxygen was used for the processing gas. As for the surface state of the pretreatment portion, the distance between peaks of the C—C bond peak and the C—O bond peak by XPS measurement was 1.69 eV. On the pretreatment part having such a surface state, a vapor deposition thin film layer made of aluminum oxide is formed to a thickness of 20 nm by reactive vapor deposition using an electron beam heating method, and the present invention according to Example 1 A gas barrier laminate was prepared.

In addition, the analysis of the surface state of the pretreatment part was performed as follows.
[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 X-ray output was measured at 100 W (10 kV-10 mA). The waveform separation analysis of the C1s waveform used a mixed function of a Gaussian function and a Lorentz function, and the charge correction was performed by correcting the CC bond peak derived from the benzene ring as 285.0 eV.

  Hydrogen gas was used as the treatment gas, except that the distance between peaks of the C—C bond peak and the C—O bond peak by XPS measurement of the pretreatment portion of the base material obtained by pretreatment was 1.68. A gas barrier laminate according to Example 2 was produced in the same manner as in Example 1.

  Oxygen gas was used as the treatment gas, except that the distance between peaks of the C—C bond peak and the C—O bond peak by XPS measurement of the pretreatment part of the base material obtained by pretreatment was 1.67. A gas barrier laminate according to Example 3 was produced in the same manner as in Example 1.

  Nitrogen gas was used as the treatment gas, except that the distance between peaks of the C—C bond peak and the C—O bond peak by XPS measurement of the pretreatment part of the base material obtained by pretreatment was 1.72. A gas barrier laminate according to Example 4 was produced in the same manner as in Example 1.

  Argon was used as the treatment gas, except that the distance between the peak of the C—C bond peak and the C—O bond peak by XPS measurement of the pretreatment part of the substrate obtained by pretreatment was 1.74. A gas barrier laminate according to Example 4 was produced in the same manner as in Example 1.

  Implementation for comparison in the same manner as in Example 1 except that an untreated PET film in which the distance between peaks of the C—C bond peak and the C—O bond peak by XPS measurement of the surface portion was 1.60 was used. A gas barrier laminate according to Example 6 was produced.

  Example in which pre-treatment for PET film was performed by corona treatment using a corona treatment apparatus, and the distance between peaks of the C—C bond peak and the C—O bond peak by XPS measurement of the treated portion was 1.64. 1 was used to produce a gas barrier laminate according to Example 7 for comparison.

  A mixed gas of argon and oxygen was used as the treatment gas, and the PET film obtained by pretreatment was carried out except that the distance between peaks of the C—C bond peak and the C—O bond peak by XPS measurement was 1.78. In the same manner as in Example 1, a gas barrier laminate according to Example 8 for comparison was produced.

Next, the A liquid and B liquid which show a composition below were mixed by the compounding ratio (weight%) 6: 4, and the solution for composite film formation was produced.
[Liquid A]
A hydrolyzed solution having a solid content of 3% by weight (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]
A 3% by weight water / isopropyl alcohol coat solution of polyvinyl alcohol (90:10 by weight of water: isopropyl alcohol).

  Then, the thin film of this solution was apply | coated by the gravure coating method on the vapor deposition thin film layer of each gas-barrier laminated body which concerns on the said Examples 1-8, and it was made to dry after that, and a 0.4 micrometer-thick composite film layer was laminated | stacked did.

  Further, using a two-component curable polyurethane adhesive, stretched nylon (15 μm) / unstretched polypropylene (70 μm) are sequentially laminated on the composite coating layer laminated in the above process by dry lamination to produce a laminated sample. did.

And these laminated samples were evaluated by performing laminate strength measurement and gas barrier measurement in the following manner.
[Measurement of laminate strength]
Measured using a Tensilon universal testing machine RTC-1250 manufactured by Orientec (JIS
Z1707 conformity). The peeling angle was 180 degrees. However, the measurement was performed while the measurement site was wetted with water. The results are shown in Table 1.

[Gas barrier measurement]
Oxygen permeability (cc / m ² · day) and water vapor permeability (g / m ² · day) were measured as indicators of bath barrier properties. The measurement was performed using the Mocon method. The measurement conditions were an oxygen transmission rate of 30 ° C.-70% RH and a water vapor transmission rate of 40 ° C.-90% RH. The results are shown in Table 1.

表からも理解されるように、Ｃ−Ｃ結合ピークとＣ−Ｏ結合ピークのピーク間距離が１．７０ｅＶを超えるＰＥＴフィルムを用いたガスバリア性積層体は、ラミネート強度が低く、レトルト処理によりガスバリア性が劣化した。

As understood from the table, the gas barrier laminate using the PET film in which the distance between the peak of the C—C bond peak and the C—O bond peak exceeds 1.70 eV has a low laminate strength. Deteriorated.

It is explanatory drawing which shows the general | schematic cross-sectional structure of the gas-barrier laminated body of this invention. It is an XPS waveform separation spectrum of an untreated PET film surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base material 2 ... Evaporated thin film layer 3 which consists of inorganic oxides ... Pre-processing part 4 ... CC bond peak 5 ... CO bond peak 6 ... COO bond peak

Claims (5)

  A gas barrier laminate in which a vapor-deposited thin film layer made of at least an inorganic oxide is laminated on a polyethylene terephthalate substrate, on at least one surface of the substrate on which the vapor-deposited thin film layer made of an inorganic oxide is laminated Has a pretreatment portion formed by pretreatment utilizing discharge treatment, and the distance between peaks of the C—C bond peak and the C—O bond peak of the pretreatment portion measured by X-ray photoelectron spectroscopy is 1. A gas barrier laminate characterized by being 65 to 1.76 eV.   The gas barrier laminate according to claim 1, wherein the vapor-deposited thin film layer made of the inorganic oxide has a thickness in the range of 10 to 100 nm.   3. The gas barrier laminate according to claim 1, wherein the inorganic oxide is any one of aluminum oxide, silicon oxide, magnesium oxide, tin oxide, indium oxide, zinc oxide, tungsten oxide, or a mixture thereof. body.   The gas barrier laminate according to any one of claims 1 to 3, wherein the pretreatment part is formed by plasma treatment using discharge treatment.   The pretreatment unit is formed by one or a plurality of continuous plasma treatments using one kind of gas of argon, nitrogen, oxygen, hydrogen, or a mixed gas thereof. The gas barrier laminate according to claim 4.

Images