JP2012189359A - Specimen for testing gas permeability and method for evaluating gas permeability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evaluate a gas permeability of a specimen, by selecting an appropriate corrosion state through observations in a short time.SOLUTION: A specimen for testing gas permeability comprises: a corrosive metal layer 2, formed on one surface of a film 1, which is to be corroded by reacting with a gas; and a non-corrosive material layer 3 which seals peripheries of the corrosive metal layer 2 including the corrosive metal layer 2 itself. The corrosive metal layer is provided with a plurality of regions having different thickness.

Description

  The present invention relates to a gas permeability test piece and a gas barrier permeability evaluation method for evaluating gas permeability by measuring a corrosion state of a metal.

  Films having a gas barrier function are used for packaging materials such as foodstuffs, precision electronic parts and pharmaceuticals. These packaging materials need to prevent the influence of the gas that permeates the packaging material in order to suppress the deterioration of the contents and maintain the functions and properties of the packaging material even during packaging. Therefore, the packaging material is required to have a gas barrier property that blocks gas permeation.

  Furthermore, in recent years, the packaging film as described above is used for industrial materials such as a back protection sheet, which is a member of a solar cell module, which is rapidly expanding as a part of global warming countermeasures, and a gas barrier layer of an organic EL element. Has come to be used.

  By the way, as a gas permeability evaluation method which is an important function of a packaging film, a metal corrosion method represented by a calcium corrosion method is known (for example, Patent Document 1).

  In this metal corrosion method, the target gas that permeates the film to be measured reacts with the corrosive metal and corrodes, so the gas permeability can be evaluated by measuring the amount of the corroded metal. Can do. Specifically, after forming a corrosive metal layer that reacts only with the gas permeated through the film to be measured, a test piece is prepared by sealing the corrosive metal layer with a non-corrosive material layer. Thereafter, the test piece is exposed to an environment having a constant gas concentration and a constant temperature, and the target gas is allowed to pass through the film to be measured, thereby measuring the corrosion state of the corrosive metal layer.

  By the way, although this kind of film seems to have uniform airtightness, there are microscopically fine spots such as fine cracks, and the gas permeates therethrough. Therefore, in the metal corrosion method, when the corrosive metal layer after exposure for a certain period of time is observed through the film to be measured, it can be seen that the corrosive metal layer is corroded from around the portion where it easily penetrates. Therefore, by measuring the corroded metal area, the gas permeability can be evaluated and the gas permeability can be measured.

  In general, the gas permeability is a value represented by the amount of gas per unit area that passes through a film in a unit time under an environment of a specified temperature and humidity.

Therefore, when evaluating using the metal corrosion method, for example, as shown in FIG. 5, the volume of the corroded portion 4c is calculated from the area and depth of the corroded portion 4c of the corrosive metal layer 2 that can be observed through the film 1 from above. Then, after obtaining the amount of gas necessary to corrode the volume equivalent, the gas permeability is obtained by dividing the amount of gas by the exposure time. According to Patent Document 1, the gas permeability T is expressed by the following formula (1).
T = m × (M [Gas] / M [Metal]) × (δhαρ / A) × 1 / t (1)
In the above formula, m is the valence of the corrosive metal, M [Gas] is the molecular weight of the permeating gas, M [Metal] is the molecular weight of the corrosive metal, δ is the area of the corroded portion of the corrosive metal layer 2, and h is the corrosion. The thickness of the corrosive metal layer 2, α is a thickness correction coefficient, ρ is the density after corrosion of the corrosive metal layer 2, A is the total area of the corrosive metal layer 2 with the corrosion 4 c and the non-corrosion part, and t is the exposure time Indicates. Here, the exposure time is the time during which the test piece is exposed to a constant gas concentration and constant temperature environment.

  Therefore, the gas permeability of the film 1 is evaluated from the area of the corroded metal, and the metal corrosion method for measuring the gas permeability is appropriate depending on the permeability, the mechanism of the permeation, the film thickness of the corrosive metal, etc. Exposure time exists.

  Therefore, for example, when the exposure time is too short, the corrosion is not sufficient, so that it is impossible to estimate the accurate corrosion volume from the area of the corroded portion. As a result, accurate gas permeability cannot be measured.

  Even if the corroded metal layer is corroded so that the corroded portion penetrates, if the corroded area is too small, an accurate corroded area cannot be measured.

  On the other hand, if the exposure time is too long, the corroded portion will spread too much, for example, as shown in FIG. 4, a part of the permeated gas 5 accumulates and does not contribute to corrosion, and an accurate gas permeability is measured. I can't.

  Therefore, in order to measure an accurate gas permeability using the metal corrosion method, it is necessary to observe in an exposure time in which the corroded portion has an appropriate corroded area.

Japanese Patent No. 4470707

  By the way, if there is a known sample that has been evaluated for gas permeability using a metal corrosion method, an appropriate exposure time can be determined. However, if a sample with unknown gas permeability is used, The exposure time to corrode until a suitable corroded area is unknown.

  Therefore, in order to accurately measure the gas permeability, it is necessary to grasp an appropriate corrosion state while continuously observing a change with time of corrosion over a long period of time, which requires time and effort.

  Therefore, the present invention has been made to solve the above-described problems, and reduces the influence of exposure time, selects an appropriate corrosion state with observation for a short time, and evaluates gas permeability. An object is to provide a test piece and a gas permeability evaluation method.

  In order to solve the above-mentioned problem, the invention corresponding to claim 1 forms a corrosive metal layer which reacts with gas and corrodes on one surface of a film, and includes the surroundings including the corrosive metal layer. In the gas permeable test piece formed by sealing with a non-corrosive material layer that does not react with the gas, the corrosive metal layer is formed such that a plurality of regions having different thicknesses are connected in a stepped manner. It is a gas permeable test piece.

  The invention corresponding to claim 2 is the gas permeable test piece, wherein the corrosive metal layer is formed so as to disperse and arrange a plurality of regions having different film thicknesses.

  According to the invention corresponding to claims 1 and 2, the corrosive metal layer reacts with the gas that has permeated the film and is corroded by exposing the test piece to an environment having a constant gas concentration and a constant temperature. However, by providing a corrosive metal layer having a plurality of thickness regions at this time, even if the gas permeation amount is the same, the corrosion area varies depending on the thickness of each region. As a result, the corrosive part completely penetrates the region from among these multiple thickness regions, and the correct gas permeability is obtained by observing and selecting a region having a corrosive state in which all permeated gases contribute to corrosion. Can be measured.

  According to a third aspect of the present invention, the corrosive metal layer includes any one of an alkali metal, an alkaline earth metal, or an alloy thereof.

  These alkali metals, alkaline earth metals or alloys thereof are rich in reactivity and are easily corroded by water vapor, so that they are suitable combinations for obtaining water vapor permeability indicating gas permeability of water vapor.

  The invention corresponding to claim 4 is characterized in that the alkaline earth metal includes calcium, magnesium, or an alloy thereof.

  These calcium, magnesium, and alloys thereof are a combination that is more suitable for obtaining water vapor permeability because it is easily corroded by water vapor, is inexpensive, and easily forms a thin film by vapor deposition.

  In the invention corresponding to claim 5, a corrosive metal layer in which a plurality of regions having different film thicknesses that react with gas and corrode is formed stepwise is formed on one surface of the film, and the corrosive A gas permeable test piece formed by sealing the periphery including a metal layer with a non-corrosive material layer that does not react with the gas is exposed to an environment having a constant gas concentration and a constant temperature, and the corrosive metal layer is exposed. The gas permeability evaluation method is characterized in that the gas permeability of the film is determined by using as an index the degree of progress of corrosion in a plurality of regions having a plurality of film thicknesses.

  Furthermore, in the invention corresponding to claim 6, a corrosive metal layer is formed on one surface of the film so as to disperse and arrange a plurality of regions having different film thicknesses that react with gas and corrode, and the corrosive A gas permeable test piece formed by sealing the periphery including a metal layer with a non-corrosive material layer that does not react with the gas is exposed to an environment having a constant gas concentration and a constant temperature, and the corrosive metal layer is exposed. The gas permeability evaluation method is characterized in that the gas permeability of the film is determined by using as an index the degree of progress of corrosion in a plurality of regions having a plurality of film thicknesses.

  According to the present invention, it is possible to provide a gas permeable test piece and a gas permeability evaluation method for reducing the influence of exposure time, selecting an appropriate corrosion state by observation for a short time, and evaluating gas permeability.

Sectional drawing which shows the gas-permeable test piece which concerns on this invention. The figure which shows schematic structure of the apparatus for producing the gas-permeable test piece which concerns on this invention. The figure explaining the small corrosion state of a corrosive metal layer when a gas-permeable test piece is exposed in the environment of a fixed gas concentration and a fixed temperature. The figure explaining the corrosive state where the gas which does not contribute to the corrosion of the corrosive metal layer when a gas-permeable test piece is exposed in the environment of a fixed gas concentration and a fixed temperature. The figure explaining the suitable corrosion state of a corrosive metal layer when a gas-permeable test piece is exposed in the environment of a fixed gas concentration and a fixed temperature.

  Hereinafter, although embodiment of this invention is described, this invention method is not limited by this embodiment, According to the kind and use of a film, it selects suitably.

  First, in the gas permeability evaluation method according to the present invention, for example, a test piece as shown in FIG. 1 is prepared from the viewpoint of evaluation using a metal corrosion method.

  That is, after the corrosive metal layer 2 that reacts with the gas and corrodes is formed at a substantially central portion of one side surface of the film 1 to be evaluated, the gas is surrounded so as to surround the periphery including the corrosive metal layer 2. By forming the non-corrosive material layer 3 that does not react with the sample, a test piece formed by sealing the corrosive metal layer 2 is produced.

  The corrosive metal layer 2 is formed to have a so-called stepped shape that changes from a thin film thickness region to a thick film thickness region from one end (left end in the drawing) side to the other end (right end in the drawing) side. That is, the corrosive metal layer 2 having a different thickness for each place is formed.

  As an apparatus for producing such a test piece, for example, as shown in FIG. 2, the film thickness of the corrosive metal layer 2 and the apparatus 12 for forming the corrosive metal layer 2 in the film holding chamber 11 is set. A device 13 for adjustment is provided, and the film 1 to be evaluated is set and held at a predetermined position in the film holding chamber 11.

  As an example of the apparatus 12 for forming the corrosive metal layer 2, for example, a vacuum deposition apparatus or a sputtering apparatus is used. As an example of the apparatus 13 for adjusting the film thickness of the corrosive metal layer 2, a plurality of stencils is used. An apparatus capable of exchanging the mask into the biofilm can be mentioned, but is not limited thereto.

  As an apparatus applied to the method of the present invention, the film 1 to be evaluated is set in the film holding chamber 11 and then the apparatus 12 for forming the corrosive metal layer 2 is used to corrode the one surface of the film 1. By adjusting the film thickness for each location using the apparatus 13 for adjusting the film thickness of the corrosive metal while forming the corrosive metal, the cross section is stepped with a plurality of regions having different film thicknesses. The corrosive metal layer 2 can be formed.

  In addition, if the apparatus 13 which adjusts the film thickness of the corrosive metal layer 2 is an apparatus capable of exchanging a plurality of stencil masks during film formation, the film can be formed by replacing the mask with a narrower pattern. It is possible to mask a part of the part which has been left and to continuously form the film in the other part. Therefore, the corrosive metal layer 2 can be processed stepwise by repeatedly exchanging the mask using the film thickness adjusting device 13 described above.

  As the corrosive metal that forms the corrosive metal layer 2, a metal containing any one of an alkali metal, an alkaline earth metal, or an alloy thereof is used, but is not limited to these materials. Alkali metals, alkaline earth metals, or alloys thereof are rich in reactivity and are easily corroded by water vapor, so that they are suitable combinations for obtaining water vapor permeability indicating the gas permeability of water vapor.

  The alkaline earth metal may include calcium, magnesium, or an alloy thereof. Calcium, magnesium, or an alloy thereof is easily corroded by water vapor, is inexpensive, and easily forms a thin film by vapor deposition. Therefore, it can be said that the combination is more suitable for obtaining water vapor permeability.

  Subsequently, the stepped corrosive metal layer 2 formed on the surface of the film 1 to be evaluated is sealed with a noncorrosive material so as to surround the corrosive metal layer 2, and the noncorrosive material layer is sealed. 3 is formed.

  The non-corrosive material may be not only a metal but also a combination with glass, resin, or the like, and it is desirable to prevent gas from permeating from a portion other than the film 1 to the corrosive metal layer 2 side as much as possible.

  Furthermore, the test piece (see FIG. 1) produced as described above is exposed to a constant gas concentration and a constant temperature environment, and the target gas is allowed to permeate through the film 1 to be evaluated, thereby corrosive metal. Corrodes layer 2.

  Then, after a lapse of a certain time, the test piece is taken out, and the corrosive metal layer 2 is observed for each region having different stepped film thicknesses using a known observation apparatus. Examples of this observation apparatus include, but are not limited to, a stereomicroscope, an optical microscope, a laser microscope, and the like that can distinguish a corroded portion and a non-corroded portion of a corrosive metal.

Therefore, as a result of observing the test piece as described above, the following was found.
The corrosive metal layer 2 reacts only with the gas that has passed through the film 1 and is corroded. At this time, since the corrosive metal layer 2 having various stepped film thicknesses is provided, the corroded area is different for each film thickness region even though the gas permeation amount is the same. That is, the corrosion state differs depending on the film thickness.

  Incidentally, in the thick film thickness region of the corrosive metal layer 2, as shown in FIG. 3, the corroded portion 4a of the corrosive metal does not penetrate the corrosive metal layer 2, or the corroded area is too small. Accurate corrosion area cannot be calculated. Therefore, the correct gas permeability cannot be measured in the thick film thickness region.

  Further, in the thin film thickness region of the corrosive metal layer 2, the corroded portion 4b is too wide as shown in FIG. 5 remains. This means that not all of the permeated gas has contributed to corrosion, and accurate gas permeability cannot be measured.

  On the other hand, in the region of the corrosive metal layer 2 having an appropriate film thickness, the corroded portion 4c of the corrosive metal penetrates the corrosive metal layer 2 as shown in FIG. Because it contributes, it is possible to calculate an accurate corrosion volume and thus to measure an accurate gas permeability.

  Therefore, from the above observation results, the corrosive metal layer 2 having a plurality of different film thicknesses is formed, and after corroding with the gas that has permeated the film 1, a film thickness region having an appropriate corrosion area is selected. If the gas permeability is obtained based on the above-described equation (1) using the corrosion area only in that region and the value of the film thickness of the corrosive metal layer 2, the accurate gas permeability can be obtained.

  Therefore, according to the above embodiment, by providing the corrosive metal layer 2 having a plurality of film thicknesses in one test piece, all the permeated gases can be obtained regardless of the gas permeability of the film 1 and the exposure time. Therefore, an accurate gas permeability can be obtained from the corrosion state (corrosion area) in the region of the film thickness in a state where the metal contributes to corrosion and the value of the film thickness of the corrosive metal layer 2.

  In addition, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. For example, as the corrosive metal layer 2, the film thickness is changed stepwise, but the main point is that the corrosive metal layer 2 having a plurality of different film thicknesses on the surface of the film 1 is dispersedly arranged. Good.

  DESCRIPTION OF SYMBOLS 1 ... File to be measured, 2 ... Corrosive metal layer, 3 ... Non-corrosive material layer, 4a to 4c ... Corrosion part, 5 ... Gas accumulated without contributing to corrosion of corrosive metal, 11 ... Film retention Chamber, 12 ... device for forming a corrosive metal layer, 13 ... device for adjusting the film thickness of the corrosive metal layer.

Claims (6)

Gas permeation formed by forming a corrosive metal layer that reacts with gas and corrodes on one surface of the film, and seals the periphery including the corrosive metal layer with a non-corrosive material layer that does not react with the gas. In the sex test piece,
A gas permeable test piece, wherein the corrosive metal layer is formed so that a plurality of regions having different film thicknesses are connected stepwise. Gas permeation formed by forming a corrosive metal layer that reacts with gas and corrodes on one surface of the film, and seals the periphery including the corrosive metal layer with a non-corrosive material layer that does not react with the gas. In the sex test piece,
A gas permeable test piece, wherein the corrosive metal layer is formed so as to disperse a plurality of regions having different film thicknesses.   The gas permeable test piece according to claim 1, wherein the corrosive metal layer includes any one of an alkali metal, an alkaline earth metal, or an alloy thereof.   The gas permeable test piece according to claim 3, wherein the alkaline earth metal includes any one of calcium, magnesium, and an alloy thereof.   On one side of the film, a corrosive metal layer is formed in which a plurality of regions having different film thicknesses that react with gas and corrode are connected in a stepped manner, and the periphery including the corrosive metal layer reacts with the gas. A gas permeable test piece sealed with a non-corrosive material layer that is not exposed is exposed to an environment of a constant gas concentration and a constant temperature, and corrosion of a plurality of film thickness regions constituting the corrosive metal layer is exposed. A gas permeability evaluation method, wherein the degree of progress is used as an index to determine the gas permeability of the film.   A corrosive metal layer is formed on one side of the film so as to disperse a plurality of regions having different film thicknesses that react with gas and corrode, and the periphery including the corrosive metal layer reacts with the gas. A gas permeable test piece sealed with a non-corrosive material layer that is not exposed is exposed to an environment of a constant gas concentration and a constant temperature, and corrosion of a plurality of film thickness regions constituting the corrosive metal layer is exposed. A gas permeability evaluation method, wherein the degree of progress is used as an index to determine the gas permeability of the film.

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