JP2006064416A - Method and apparatus for measuring gas barrier property of plastic molded body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas barrier property measuring method capable of solving the problem that the evaluation of gas barrier properties has varied due to the amount of moisture absorption of plastic and highly precisely measuring the gas barrier properties of plastic molded bodies such as containers with satisfactory responsiveness in measurement values independent of the amount of moisture absorption. <P>SOLUTION: In the gas barrier property measuring method for measuring the amount of permeation of a gas to be measured which permeates a plastic molded body such as a plastic container, a plastic sheet, a plastic film, etc. with a gas-analysis apparatus, the gas barrier property measuring method has a process for reducing the concentration of impurities in the plastic molded body. The process includes a drying process for drying the plastic molded body at least by irradiating the plastic molded body with ultraviolet rays, placing the plastic molded body in a pressure-reduced atmosphere, or performing electrical discharge cleaning on the plastic molded body. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a gas barrier property measurement method for quickly and accurately evaluating the gas barrier performance of a plastic molded article, and further extends to a measurement method suitable for quality control of gas barrier properties when mass-producing gas barrier plastic containers. The present invention also relates to a gas barrier property measuring apparatus for a plastic molded body.

  A gas barrier plastic container is disclosed in Patent Document 1, for example. In Patent Document 1, the oxygen barrier property of a plastic container is measured at 40 ° C. using OX-TRANTWIN manufactured by MODERN CONTROL. Moreover, about the carbon dioxide gas barrier property, the permeation | transmission amount of a carbon dioxide gas is measured at 25 degreeC using the PERMATRANC-4 type | mold made from MODERN CONTROL.

  The method disclosed in Patent Document 1 is mainly used for measuring the gas barrier properties of plastic molded articles such as plastic containers, plastic sheets or plastic films. In the case of a plastic container, since the wall thickness is thick and the shape of the container is complicated, it takes about one week until the measurement value is stabilized. Therefore, there has been no method that can quickly evaluate the gas barrier property.

As an invention for measuring the gas concentration with high accuracy by atmospheric pressure ionization mass spectrometry, for example, a method for measuring the gas concentration of hydrogen is disclosed in Patent Document 2. The technique of Patent Document 2 does not directly measure hydrogen, but generates water (steam) from hydrogen and measures the water to obtain a hydrogen concentration by conversion. The reason for generating water as described in the 10th line of the right column on page 2 of the specification of Patent Document 2 is that hydrogen is not efficiently ionized to the parent ion (H ₂ ⁺ , mass 2), so that it is special for mass spectrometry. This is because there is a problem.

Attempts to evaluate gas barrier properties using an atmospheric pressure ionization mass spectrometer (APIMS) have not yet been made.
JP-A-8-53116 Japanese Patent Laid-Open No. 11-118763

  As in Patent Document 1, the gas permeation meter measures oxygen or carbon dioxide separately. In the experience of the present inventors, when measuring gas permeability using the apparatus described in Patent Document 1, for example, when measuring oxygen permeability, it takes at least one week for the measured value to stabilize. Therefore, if an attempt is made to increase the accuracy of the measurement value, it takes time exceeding one week to measure the gas barrier property of one plastic container. The reason why the measurement takes a long time is that the inventors of the apparatus described in Patent Document 1 cannot increase the flow rate of the carrier gas that carries the permeated measurement target gas from the viewpoint of ensuring the measurement accuracy. It is estimated that it takes a long time because of poor gas circulation and slow response of measured values.

  Also, some plastic resins have a large hygroscopicity depending on the type. For example, a polyethylene terephthalate (PET) container has a large hygroscopic property, and the relative humidity at 20 ° C. is 60 to 80%, and 0.3 to 0 per 100 g of resin. May absorb up to 5g of water. The present inventors have found that the presence of an adsorbed gas such as water molecules absorbed in the resin as impurities affects the detector, and the measured value of oxygen permeability varies greatly depending on the water content of the resin. .

  If the container is stored in a warehouse or the like after molding the plastic container, the container will absorb moisture. When checking the quality of gas barrier properties over time after molding a container in a plastic container molding factory, or when making the gas barrier property of plastic containers one of the quality confirmation items when a beverage filling factory accepts plastic containers The detector is affected by the difference in the amount of moisture absorption, and the evaluation of the gas barrier properties varies.

  Overcoming the problem of gas barrier property evaluation variation due to the moisture absorption of the plastics described above, the gas barrier property of plastic molded bodies including containers can be measured with good response and accuracy regardless of the amount of moisture absorption. It is an object of the invention.

  That is, the object of the present invention is to measure the gas barrier property by reducing the concentration of impurities such as water molecules adsorbed and sorbed on the plastic molded body before measuring the measurement target gas that has permeated through the plastic molded body. It is to provide a gas barrier property measuring method with improved accuracy. In particular, it is an object of the present invention to improve the accuracy of gas barrier property measurement by quickly preparing a plastic molded body from which the influence of moisture has been removed by drying the plastic molded body. Furthermore, by adopting a mass spectrometer, especially an atmospheric pressure ionization mass spectrometer, and flowing a relatively large amount of carrier gas, the permeation of the gas to be measured can be detected with good response and high accuracy, greatly reducing the measurement time. And providing a gas barrier property measuring method. At this time, not only one measurement target gas but also a plurality of measurement target gases are simultaneously measured with high accuracy.

  Another object of the present invention is to provide a gas barrier property measuring method for a plastic molded body, in particular, a plastic container or a gas barrier plastic container having a gas barrier thin film coated on either or both of the inner surface and the outer surface. .

  An object of the present invention is to provide a method for measuring oxygen gas barrier properties of a plastic molded body, particularly a method for measuring oxygen gas barrier properties due to permeation of oxygen from an atmospheric atmosphere.

  Another object of the present invention is to adjust the measurement target gas to one of oxygen gas, carbon dioxide gas, hydrogen gas, or a combination thereof, and to adjust the measurement target gas-containing atmosphere so that the measurement target gas has a predetermined partial pressure. The gas barrier property of any one of oxygen gas, carbon dioxide gas and hydrogen gas, or a combination of them is created by the measurement target gas-argon standard gas or the measurement target gas-nitrogen gas standard gas. It is to provide a method of eliminating and accurately measuring.

  Furthermore, the object of the present invention is to make the measurement target gas an oxygen gas having a mass number of 18 so that oxygen gas existing in the plastic resin before measurement (the oxygen gas having a mass number of 16 is 99.762% and the mass number is 17). (Oxygen gas of 0.038%, oxygen gas of mass number 18 is 0.200%, oxygen gas of mass number 16 is the majority) and oxygen gas that permeates the plastic resin during measurement is measured separately. Thus, it is to provide a gas barrier property measuring method that completely eliminates the influence of oxygen gas existing in the plastic resin before the measurement. In plastic resin, it permeates by diffusion permeation according to the gas concentration gradient, but the initial data of normal measurement methods are measured values for both oxygen gas existing in the plastic resin before measurement and oxygen gas permeated by diffusion permeation. Will be detected. In the present invention, it is expected that the true measured value of the gas barrier property can be quickly detected by detecting only oxygen gas permeated by diffusion permeation from the beginning of measurement.

  Furthermore, an object of the present invention is to provide a gas barrier property of a plurality of gas types as a measurement target gas as a combination of at least one of mass 16 oxygen gas, carbon dioxide gas or hydrogen gas and mass 18 oxygen gas. It is to provide a measurement method capable of performing simultaneous measurement of the above.

  When mass-producing gas barrier plastic containers, a single coating chamber for coating a gas barrier thin film on the container cannot be used, and a plurality of coating chambers can be operated simultaneously or sequentially. Realistic. Therefore, another object of the present invention is to evaluate the gas barrier property of each container when coating the gas barrier thin film in a mass production state using a plurality of coating chambers for a plastic container, and to form a film for each coating chamber. It is to provide a gas barrier property measuring method capable of grasping the operating state of a coating chamber by comparing gas barrier properties of containers. This is because the quality of the deposited gas barrier thin film often depends on whether or not the coating chamber is operating normally. In particular, since the present invention can measure the gas barrier property quickly, it is expected that the quality evaluation of the gas barrier property of the container on the production line can be judged from the result of this measurement method. In the conventional measurement method that requires an evaluation time of one week or more, it takes too much time as an evaluation method on the production line.

  An object of the present invention is to perform measurement by quickly performing gas replacement by setting the flow rate of argon gas or nitrogen gas supplied to the argon atmosphere side or nitrogen atmosphere side to a predetermined value or more in the atmosphere adjustment step and the measurement target gas measurement step. To reach a steady state that can be started early.

  An object of the present invention is to provide an apparatus capable of performing the gas barrier property measurement.

  In view of the above-mentioned problems, the present inventors have attempted to improve the accuracy of measurement by suppressing variations in measurement data due to impurities such as water molecules, and efficiently perform gas replacement required for measurement. In order to increase the speed of measurement, it has been intensively developed. (1) The plastic molded body should be reduced in impurity concentration before gas permeability measurement, for example, dried, (2) The plastic molded body If the impurity concentration is reduced, for example, assuming drying, high accuracy and high speed can be realized even if various gas measurement methods are used, preferably mass spectrometry, more preferably atmospheric pressure ionization mass spectrometry. The present invention has been completed by finding that the above problems can be solved more effectively by adopting the method.

  That is, the gas barrier property measuring method for a plastic molded body according to the present invention is a gas barrier property measuring method for measuring the permeation amount of a gas to be measured that permeates a plastic molded body such as a plastic container, a plastic sheet, or a plastic film with a gas analyzer. And a step of reducing the impurity concentration of the plastic molded body. Here, as a step of reducing the impurity concentration of the plastic molded body, the plastic molded body is irradiated with ultraviolet rays, or the plastic molded body is placed in a reduced pressure atmosphere, or the plastic molded body is discharged and washed. And a drying step of drying the plastic molded body by performing at least one of the above. Here, the drying step may be performed simultaneously or before and after heating in a temperature range in which the plastic molded body is not deformed or thermally deteriorated.

  In the method for measuring gas barrier properties of a plastic molded body according to the present invention, one side of the wall surface of the plastic molded body is a measurement target gas-containing atmosphere, and the other side which is the front and back relation of the wall surface is the measurement target gas after permeation. Including an atmosphere adjustment step in which a carrier gas atmosphere is carried to the gas analyzer. Here, the carrier gas atmosphere is preferably an argon atmosphere or a nitrogen gas atmosphere. Here, in order to shorten the time required for measurement, it is preferable to simultaneously perform the drying step in the atmosphere adjustment step. Furthermore, in the gas barrier property measuring method for a plastic molded body according to the present invention, the gas to be measured permeates the plastic molded body from one side of the wall surface to the other side, and the permeation amount of the gas to be measured is substantially in a steady state. The measurement object gas measurement step for measuring the permeation amount by the gas analyzer when the gas analysis device is used is included.

  In the method for measuring gas barrier properties of a plastic molded body according to the present invention, the drying step includes a step of removing moisture absorbed by the plastic molded body. Further, in the drying step, the adsorption gas adsorbed on one side of the wall surface of the plastic molded body is replaced with a gas in the atmosphere containing the measurement target gas, and adsorbed on the other side of the wall surface of the plastic molded body. Replacing the adsorbed gas with the gas in the carrier gas atmosphere.

  In the gas barrier property measuring method for a plastic molded article according to the present invention, the gas analyzer is preferably a mass spectrometer, more preferably an atmospheric pressure ionization mass spectrometer.

  In the gas barrier property measuring method for a plastic molded body according to the present invention, the plastic molded body is a plastic container, or a gas barrier plastic container in which a gas barrier thin film is coated on one or both of the inner surface and the outer surface. In some cases, in the atmosphere adjustment step, it is preferable that the outside of the container is a gas-containing atmosphere to be measured and the inside of the container is the carrier gas atmosphere.

  Here, in the gas barrier property measuring method for a plastic molded body according to the present invention, it is preferable that the measurement target gas is oxygen gas, and the measurement target gas-containing atmosphere is an air atmosphere.

  Alternatively, the measurement target gas is any one of oxygen gas, carbon dioxide gas, hydrogen gas, or a combination thereof, and the measurement target gas-containing atmosphere is adjusted so that the measurement target gas has a predetermined partial pressure. A gas-argon atmosphere or a measurement target gas-nitrogen gas atmosphere is preferable.

  Alternatively, the measurement target gas is an oxygen gas having a mass number of 18, and the measurement target gas-containing atmosphere is an oxygen gas-argon atmosphere having a mass number of 18 adjusted so that the oxygen gas having a mass number of 18 has a predetermined partial pressure. Alternatively, an oxygen gas-nitrogen gas atmosphere having a mass number of 18 is preferable.

  Alternatively, the measurement target gas is a mixed gas of at least one of oxygen gas, carbon dioxide gas or hydrogen gas having a mass number of 16 and oxygen gas having a mass number of 18, and the measurement target gas-containing atmosphere is the measurement target gas It is preferable that the measurement target gas-argon atmosphere adjusted so that the gas has a predetermined partial pressure or the measurement target gas-nitrogen gas atmosphere.

  In the gas barrier property measuring method for a plastic molded body according to the present invention, the plastic container is provided with a plurality of coating chambers for coating a gas barrier thin film on one or both of the inner surface and the outer surface of the plastic container. A gas barrier plastic container that is mass-produced by operating the coating chambers simultaneously or sequentially, and each time a predetermined number of films are formed for each coating chamber, the drying step, the atmosphere adjustment step, and the measurement target gas measurement step are performed. It is preferable to have a chamber operation determining step for determining a malfunction of the coating chamber by comparing the gas barrier properties of the gas barrier plastic container for each coating chamber.

  In the gas barrier property measuring method for a plastic molded body according to the present invention, an argon flow rate per minute or a nitrogen flow rate per minute supplied to the carrier gas atmosphere side in the atmosphere adjustment step or the measurement target gas measurement step. Is preferably at least twice the capacity of the plastic container.

  The gas barrier property measuring apparatus for a plastic molded body according to the present invention includes a gas analyzing unit, a chamber for housing a plastic molded body such as a plastic container, a plastic sheet or a plastic film, and one of the plastic molded bodies in the chamber. A jig separating a first space in contact with the surface and a second space in contact with the other surface, a measurement target gas supply unit for supplying a measurement target gas to the first space, and the plastic molded body from the first space A carrier gas supply unit that supplies a carrier gas for transporting the measurement target gas that has passed through the second space to the gas analysis unit, and a drying unit that dries the plastic molded body. Features.

  Here, the drying means heats an ultraviolet generator that irradiates the plastic molded body with ultraviolet rays, a vacuum pump that evacuates the interior of the chamber, a discharge generator that discharges and cleans the plastic molded body, or the plastic molded body. It is preferable to have at least one of the heaters.

  According to the present invention, the problem that the evaluation of gas barrier properties varies due to moisture absorption of plastics is overcome, and the gas barrier properties of plastic molded bodies including containers are measured with good response and high accuracy regardless of the amount of moisture absorption. did it.

  Hereinafter, although an embodiment is shown and explained in detail about the present invention, the present invention is limited to these descriptions and is not interpreted.

  Examples of the plastic molded body according to the present invention include a plastic container, a plastic sheet, and a plastic film. In the present embodiment, a plastic container, particularly a beverage container will be described as an example. In the case of measuring the gas barrier property of a film thickness of several tens of μm, such as a plastic film, the film thickness is thin, so that it may take a relatively short time. When a plastic container is used as a measurement target, the resin wall thickness is 0.3 to 1 mm, and thus quick measurement is required as compared with the case of a film. Furthermore, the beverage container has a three-dimensional shape, the shape inside the container is complicated, and it takes a long time to completely replace the gas by flowing the carrier gas. Therefore, it is difficult to evaluate the gas barrier property at high speed and with high accuracy. The present invention is not affected by the shape of the container, and the use of the container can be exemplified by carbonated drinks such as beer, fruit juice drinks, nutritional drinks, and pharmaceuticals.

  Resin used when molding the plastic container of the present invention is polyethylene terephthalate resin (PET), polyethylene terephthalate-based copolyester resin (copolymer using cyclohexane dimethanol instead of ethylene glycol as the alcohol component of polyester) Eastman Chemical), polybutylene terephthalate resin, polyethylene naphthalate resin, polyethylene resin (PE), polypropylene resin (PP), cycloolefin copolymer resin (COC, cyclic olefin copolymer), ionomer resin, poly- 4-methylpentene-1 resin, polymethyl methacrylate resin, polystyrene resin (PS), ethylene-vinyl alcohol copolymer resin, acrylonitrile resin, polyvinyl chloride resin, Vinylidene chloride resin (PVDC), polyamide resin, polyamideimide resin, polyacetal resin, polycarbonate resin (PC), polysulfone resin, or tetrafluoroethylene resin, acrylonitrile-styrene resin, polyethersulfone resin, acrylonitrile-butadiene-styrene Resin. Among these, PET is particularly preferable. In the present invention, a PET bottle will be described as an example of a plastic container.

The water absorption rate of plastic (24 hours, 23 ° C.) is divided into three.
(1) PE: <0.01%, PP: <0.005%, PS: 0.04-0.06%, PVDC: Slightly as water absorption.
(2) As an intermediate thing, PET: 0.3-0.5%, PC: 0.35%, polyether sulfone: 0.3-0.4%.
(3) Polyimide: 2.9%, nylon 6: 9.5%, cellulose acetate: 5-9% as a high water absorption rate.

The plastic molded body according to this embodiment may be a gas barrier plastic container in which a gas barrier thin film is coated on one or both of the inner surface and the outer surface. Examples of the gas barrier thin film coated on the wall surface of the plastic container include SiOx, DLC (diamond-like carbon), Si-containing DLC, polymer-like carbon, aluminum oxide, polymer-like silicon nitride, and acrylic acid resin coating. Among them, DLC is excellent in oxygen barrier properties and water vapor barrier properties, is chemically inert, has carbon and hydrogen as its main components, can be disposed of in the same way as plastic, and is flexible because it is plastic. It is particularly preferable because of the followability in stretching. The DLC film referred to in the present invention is a film called i-carbon film or hydrogenated amorphous carbon film (aC: H), and includes a hard carbon film. The DLC film is an amorphous carbon film and also has SP ³ bonds. A hydrocarbon gas such as acetylene gas is used as a source gas for forming the DLC film, and a Si-containing hydrocarbon gas is used as a source gas for forming the Si-containing DLC film. By forming such a DLC film on one or both of the inner surface and the outer surface of a plastic container, a container that can be used one-way or in a returnable manner as a container for carbonated beverages, sparkling beverages, and the like is obtained.

  The gas barrier thin film can be coated on the inner surface and / or the outer surface of the plastic container, but the gas barrier property is ensured and the sorbent of the filler to the plastic or contained in the plastic. Considering that it is possible to prevent elution of a trace component into the packing and that it is economical, it is particularly preferable to form a gas barrier thin film on the inner surface. Moreover, as a film-forming method of a DLC film, it is the film-forming method described in patent document 1, for example.

  The gas barrier property measuring method for a plastic molded body according to the present embodiment is a method for measuring the permeation amount of a measurement target gas that permeates through the plastic molded body using a gas analyzer, and (1) reducing the impurity concentration of the plastic molded body. The process, for example, the plastic molded body is dried by irradiating the plastic molded body with ultraviolet rays, placing the plastic molded body in a reduced-pressure atmosphere, or discharging and washing the plastic molded body. At least a drying step. This drying step may include heating in a temperature range that does not cause deformation or thermal degradation of the plastic molded body simultaneously or before and after. The drying step may include a step of removing moisture absorbed by the plastic molded body. Further, in the drying process, the adsorption gas adsorbed on one side of the wall surface of the plastic molded body is replaced with the gas in the atmosphere containing the measurement target gas, and the adsorbed gas adsorbed on the other side which is the front and back relation of the wall surface of the plastic molded body May be replaced with a gas in a carrier gas atmosphere such as argon or nitrogen gas.

  The method for measuring gas barrier properties of a plastic molded body according to the present embodiment is as follows: (2) One side of the wall surface of the plastic molded body is a gas-containing atmosphere to be measured, and the other side that is the front and back relation of the wall surface is a carrier such as argon or nitrogen gas And an atmosphere adjusting step for forming a gas atmosphere. This carrier gas is a gas that conveys the measurement target gas after permeation to the gas analyzer, and may contain 0.5 to 3.0% of hydrogen gas for removing impurity oxygen. The hydrogen gas for removing impurity oxygen reacts with the impurity oxygen in the carrier gas by the catalyst before touching the plastic molded body. On the other hand, since it does not react with oxygen after touching the catalyst, it does not react with permeated oxygen.

  In the gas barrier property measuring method for a plastic molded body according to the present embodiment, (3) the gas to be measured permeates the plastic molded body from one side of the wall surface to the other side, and the permeation amount of the gas to be measured is substantially steady. When the concentration of the gas to be measured reaches a constant value at the detector, the amount of permeation is measured by various gas analyzers, preferably mass spectrometers, more preferably atmospheric pressure ionization mass spectrometers. A measuring object gas measuring step.

  When the present inventors have impurities such as water molecules due to moisture absorption in the molecular structure of the plastic molding to be measured, the impurities such as water molecules affect the detector, and oxygen, carbon dioxide, etc. It has been found that while the measured value becomes unstable, it is possible to eliminate the adverse effect of water molecules by removing water molecules absorbed by the plastic molding. For example, the PET resin can absorb 0.3 to 0.5 g of water per 100 g. When a beverage filling factory or the like accepts a plastic container coated with a gas barrier thin film, it is a normal operation to perform a quality inspection as to whether or not it has a prescribed gas barrier property. Here, the plastic container coated with the gas barrier thin film often causes moisture absorption. If the gas barrier performance of this container is measured as it is, a measurement error will be included depending on the moisture absorption state of the container. In the present invention, it is preferable to provide a step of reducing the impurity concentration of the plastic molded body, for example, a drying step, before measuring the gas barrier property. The drying process is performed for the purpose of removing water molecules absorbed by the plastic molded body, eliminating the adverse effect of water molecules on the detector, and reducing the influence of the adsorbed gas adsorbed on the surface of the plastic molded body. Is. Further, as a means for removing water molecules absorbed by the plastic molded body, a means of continuously flowing a large amount of dry argon or dry nitrogen gas into the plastic container is also conceivable. However, since the diffusion rate of water molecules depends on temperature, it has been found that it takes about one week to remove water molecules from the resin. In comparison with this, drying is performed by irradiating the plastic molded body with ultraviolet rays, placing the plastic molded body in a reduced-pressure atmosphere, or performing discharge cleaning of the plastic molded body. Water molecules can be removed at high speed. At this time, drying can be promoted by heating the plastic molded body in a temperature range that does not cause deformation or thermal degradation at the same time or before and after. And it is preferable to continue gas substitution inside the plastic container with dry argon or dry nitrogen gas simultaneously with drying. This is not for the purpose of drying the resin with dry argon or dry nitrogen gas, but for the purpose of discharging dry argon or dry nitrogen gas as a carrier gas for water molecules diffused and released from the inside of the resin to the outside of the resin. It is not necessary to flow a large amount of dry argon or dry nitrogen gas. Note that APIMS, which is a detector used in the present invention, is easily affected by water molecules, and therefore requires a drying step.

  In the drying step, when the plastic molded body is irradiated with ultraviolet rays, ultraviolet rays having a wavelength of 350 nm or less, preferably 240 to 300 nm are used. By irradiating this ultraviolet ray, the plastic molded body can be dried. More specifically, it is preferable to use ultraviolet rays generated by combining a low-pressure mercury lamp and ozone-less quartz glass L. The low-pressure mercury lamp has dominant wavelengths at 185 nm and 254 nm, but the wavelength of 185 nm generates ozone. Ozone causes damage to equipment and organic matter. Therefore, the ozone-less quartz glass L that is prevented from transmitting ultraviolet light of less than 240 nm by adding heavy metal is used in combination. The output is, for example, 2-15W. The ultraviolet irradiation time is preferably 1 to 2 hours. The ultraviolet irradiation site is the surface of the plastic molded body, and if the plastic molded body is a container, it is the inner surface of the container or the outer surface of the container. In the case of irradiating the inner surface of the container with ultraviolet light, for example, a tubular low-pressure mercury lamp is inserted from the container mouth, and then light is emitted.

  In the drying process, when the plastic molded body is placed in a reduced pressure atmosphere, the plastic molded body is accommodated in a vacuum oven (for example, vacuum oven VT220 manufactured by Enomoto Kasei Co., Ltd.). The vacuum condition of the vacuum oven is, for example, 1 to 50 Pa, and vacuum drying is performed for 1 to 2 hours. It is also possible to appropriately change the vacuum pressure and vacuum drying time in the vacuum oven in accordance with conditions such as the type, thickness, and size of the plastic molded body. When the plastic molded body is brought into a completely dry state by vacuum drying, it takes time until re-adsorption occurs and an equilibrium state is reached. At this time, a value lower than the actual gas permeability is detected as the analytical value, and gradually increases toward the equilibrium value. Therefore, it is preferable to dry to such an extent that it is in an equilibrium state, not an absolutely dry state, according to conditions such as the type, thickness, and size of the plastic molded body.

  In the drying step, when the plastic molded body is subjected to discharge cleaning, if the plastic molded body is a container, the plastic molded body is dried by applying plasma to the inner surface of the container or the outer surface of the container. Plasmaized gas collides with the surface of the plastic molded body, and at this time, adhering impurities such as water molecules are blown off and dried. As the discharge gas as the pretreatment gas, for example, a rare gas such as argon, helium, or neon, or oxygen, nitrogen, or hydrogen is preferably used. Plasma excitation is performed using a high frequency power source or a microwave power source. The discharge conditions vary depending on the container conditions such as the size, shape, and thickness of the container, but the output of the high-frequency power source or microwave power source is 100 to 1000 W, for example. The discharge cleaning time is set to such a time that the container is not thermally deformed, for example, 2 seconds to 10 minutes. The pressure during discharge is, for example, 13.3 to 1333 Pa.

  Simultaneously with or before or after performing at least one of ultraviolet irradiation, vacuum drying, or discharge cleaning, the plastic molded body may be heated in a temperature range that does not cause deformation or thermal degradation. In order to dry quickly, it is effective to blow dry argon or dry nitrogen gas hot air on the container, but if the container is heated to a temperature higher than the glass transition point of plastic, the container will shrink and deform. Become. Therefore, in this invention, it is preferable to dry at the temperature below the grade which does not produce thin film degradation, such as shape degradation and peeling of a gas barrier thin film, and a crack. For example, PET bottles are preferably dried at 60 to 80 ° C.

  An example of a combination of drying methods in the drying step is as follows. These are combinations of ultraviolet irradiation only, vacuum drying only or discharge cleaning only, ultraviolet irradiation and vacuum drying, ultraviolet irradiation and discharge cleaning, vacuum drying and discharge cleaning, or ultraviolet irradiation, vacuum drying and discharge cleaning. Also, UV irradiation and heat drying, vacuum drying and heat drying, discharge cleaning and heat drying, UV irradiation and vacuum drying and heat drying, UV irradiation and discharge cleaning and heat drying, vacuum drying and discharge cleaning and heat drying, or UV light Each combination of irradiation, vacuum drying, discharge cleaning, and heat drying may be used. These are appropriately selected according to conditions such as the type, thickness and size of the plastic molded body.

  The atmosphere adjustment step is provided in order to provide a gas concentration difference between the front surface and the back surface in the vicinity of the front and back wall surfaces of the plastic molded body, and to diffuse the gas from the high concentration side to the low concentration side. Here, in the atmosphere adjustment step, the drying step may be performed simultaneously. The atmosphere adjustment process takes some time to stabilize, and the drying process takes some time for heating and cooling, but these can be performed simultaneously, leading to a reduction in the time required for measurement.

  Taking a plastic container as an example, it is preferable that the outside of the plastic container is a gas-containing atmosphere to be measured and the inside of the plastic container is a carrier gas atmosphere such as an argon atmosphere or a nitrogen gas atmosphere. In this case, the measurement target gas concentration outside the container is high, the measurement target gas concentration inside the container is low, and the measurement target gas diffuses and penetrates into the resin from the outer surface of the container toward the inner surface of the container. The plastic container may be a gas barrier plastic container in which a gas barrier thin film is coated on one or both of the inner surface and the outer surface.

  In one form of measuring the oxygen gas barrier property, the measurement target gas is oxygen gas, and the measurement target gas-containing atmosphere is an air atmosphere. In order to transport the permeated oxygen gas to the detector, argon gas or nitrogen gas is flowed as a carrier gas at a flow rate of, for example, 500 to 2000 ml / min. Argon gas or nitrogen gas becomes a replacement gas until it reaches a steady state.

  In the present embodiment, it is preferable to remove water molecules as much as possible because the presence of water molecules in the measurement path causes a decrease in measurement accuracy. That is, it is preferable to use high-purity argon or high-purity nitrogen gas as the carrier gas, and to remove water molecules by installing a purifier immediately after the argon supply source or the nitrogen gas supply source.

  In the form in which the oxygen gas barrier property, the carbon dioxide gas barrier property, or the hydrogen gas barrier property is measured individually or in combination, and the gas barrier property is simultaneously measured, the gas to be measured is any one of oxygen gas, carbon dioxide gas, hydrogen gas, or those gases. A combination. The measurement target gas-containing atmosphere is a measurement target gas-argon atmosphere or a measurement target gas-nitrogen gas atmosphere adjusted so that the measurement target gas has a predetermined partial pressure. In this case, oxygen gas-argon gas, carbon dioxide gas-argon gas, hydrogen gas-argon gas, oxygen gas-carbon dioxide gas-argon gas, oxygen gas-hydrogen gas-argon gas, Hydrogen gas-carbon dioxide gas-argon gas or oxygen gas-carbon dioxide gas-hydrogen gas-argon gas is respectively adjusted to a predetermined partial pressure to be prepared as a standard gas and flowed through the gas path. Alternatively, in order to create a measurement object gas-nitrogen gas atmosphere, oxygen gas-nitrogen gas, carbon dioxide gas-nitrogen gas, hydrogen gas-nitrogen gas, oxygen gas-carbon dioxide gas-nitrogen gas, oxygen gas-hydrogen gas-nitrogen gas, Hydrogen gas-carbon dioxide gas-nitrogen gas or oxygen gas-carbon dioxide gas-hydrogen gas-nitrogen gas is adjusted to a predetermined partial pressure, prepared as a standard gas, and flowed through the gas path. Compared with the case where the measurement target gas-containing atmosphere when measuring the gas barrier property of oxygen gas is an air atmosphere, the influence of impurity gas, particularly water vapor, is eliminated, so that the measurement accuracy can be improved.

  Another embodiment for measuring the oxygen gas barrier property is that the measurement target gas is an oxygen gas having a mass number of 18, and the atmosphere containing the measurement target gas is adjusted so that the oxygen gas having a mass number of 18 has a predetermined partial pressure. An argon atmosphere or an oxygen gas-nitrogen gas atmosphere having a mass number of 18 adjusted so that the oxygen gas having a mass number of 18 has a predetermined partial pressure. The reason for using oxygen gas having a mass number of 18 is as follows. Normal oxygen gas has a mass number of 16, and APIMS, which is a detector for atmospheric pressure ionization analysis, can detect the difference in mass number. On the other hand, molecular properties such as gas permeation are the same because they are isotope elements. Since the proportion of oxygen gas having a mass number of 18 in the plastic resin is as low as 0.200% from the beginning, the oxygen gas having a mass number of 18 is measured as the measurement target gas, so that the oxygen gas that originally exists in the plastic resin is measured. Detection errors due to diffusion penetration of gas (mass number 16) can be separated. That is, when oxygen gas having a mass number of 18 is measured, it can be seen in real time that it begins to permeate the plastic molded body.

  The application form in the case of using oxygen gas having a mass number of 18 as a measurement target gas is that the measurement target gas is at least one of oxygen gas, carbon dioxide gas or hydrogen gas having a mass number of 16 and oxygen gas having a mass number of 18 The measurement target gas-containing atmosphere is a measurement target gas adjusted so that the measurement target gas has a predetermined partial pressure-a standard gas in an argon atmosphere, or a measurement target adjusted so that the measurement target gas has a predetermined partial pressure. A standard gas in a gas-nitrogen gas atmosphere is prepared to create the atmosphere. In this case, detection errors due to diffusion and penetration of oxygen gas (mass number 16) present in the plastic resin from the beginning can be separated, and simultaneous analysis using carbon dioxide gas, oxygen gas, hydrogen gas, or a combination of these gases becomes possible. . By using standard gas, the influence of impurity gas can be eliminated.

Table 1 shows the composition of the standard gas of measurement object gas-argon gas and the composition of the standard gas of measurement object gas-nitrogen gas.

  In the measurement target gas measurement process, the measurement target gas passes through the plastic molded body from one side of the wall surface to the other side, and the measurement target gas that has permeated argon gas or nitrogen gas as the carrier gas is transported to the gas detector. Then, the permeation amount of the measurement target gas is obtained by measuring the gas concentration of the measurement target gas when the permeation amount of the detected measurement target gas reaches a steady state. For example, when a plastic container is used as a measurement target, the atmosphere outside the container includes a desired constant partial pressure of the measurement target gas. On the other hand, since the measurement object gas which permeate | transmitted argon gas or nitrogen gas as carrier gas is sequentially conveyed to a detector inside a container, measurement object gas concentration (partial pressure) is near zero.

Ｄ．Ｗ．Ｖａｎ Ｋｒｅｖｅｌｅｎ,Ｐｒｏｐｅｒｔｉｅｓ ｏｆ Ｐｏｌｙｍｅｒｓ,ｐ５５５ Here, the gas permeability coefficient P of the plastic is expressed by Equation 1 using the gas diffusion rate D in the plastic and the gas solubility coefficient S in the plastic.
(Formula 1) P = D × S
The gas permeation amount Q of the plastic is expressed by Equation 2 using the gas permeation coefficient P, the permeation area A, the permeation time t, and the pressure p.
(Formula 2) Q = P × A × t × p
The gas permeation amount Q of the plastic can be expressed by Equation 2. In actual measurement, the gas concentration to be measured outside the plastic container (which is a predetermined concentration) and the gas concentration to be measured inside the container (measured as described above) If the concentration gradient of the target gas concentration is substantially zero), a measurement error will occur. The time until gas molecules diffuse in the plastic and the concentration gradient of the gas molecules in the plastic reaches a steady state is called “delay time”. As shown in Equation 3, the delay time is proportional to the square of the plastic thickness and inversely proportional to the diffusion coefficient.
(Expression 3) Delay time = (Plastic thickness) ² / (6 × Diffusion coefficient D)
Here, Table 2 which is data shown in Non-Patent Document 1 is shown.

D. W. Van Krevelen, Properties of Polymers, p555

  As is apparent from Equation 3, the diffusion coefficient D varies depending on the type of measurement target gas, and the delay time also varies. However, the measurement target gas permeates normally when each measurement target gas diffuses and permeates through the resin. It can be said that it became a state. However, the plastic molded body may have a complicated shape, and it is necessary for the permeation to be in a steady state in all the parts. Therefore, the gas is measured after a predetermined time has elapsed since it was detected that the gas to be measured has permeated. It is preferable to determine that the transmission has reached a steady state. Furthermore, even in a state where permeation is constantly performed at each part of the container, the gas to be measured stays inside the container before being transported to the detector. The gas inside the container (in this case, argon gas or nitrogen gas, which is a carrier gas, and the gas to be measured) becomes a constant concentration, and the influence of this gas retention disappears until the steady state is reached. Therefore, until the permeation amount of the measurement target gas reaches a steady state, the permeation of the measurement target gas must be in a steady state and the gas concentration inside the container must be constant.

The gas to be measured is detected by a gas analyzer. Preferably, the measurement is performed by a non-deflection mass spectrometer such as a quadrupole mass spectrometer or a time-of-flight mass spectrometer, or a deflection mass spectrometer such as a magnetic field deflection mass analyzer, a trochoid mass analyzer, or an omegatron. . More preferably, an atmospheric pressure ionization mass spectrometer is used. Atmospheric pressure ionization mass spectrometry (APIMS) by atmospheric ionization (API) is a technique that can analyze even a very small amount of impurities, and is characterized by high sensitivity and real-time measurement. This is because the APIMS gas inlet can operate at atmospheric pressure. In order to achieve high sensitivity with a mass meter, it is necessary to increase the ionization amount of the detection target component (high efficiency ionization), but APIMS achieves high efficiency ionization by two-stage ionization. First, a sample gas (main component: C, impurity: X) containing a small amount of impurities is primarily ionized by corona discharge in an ionization section. In primary ionization, as with many ionization methods, only a small portion of the sample is ionized. The composition of the generated ions is almost the same as that of the sample, and consists of most main component ions C ⁺ and a few impurity ions X ⁺ . In the electron impact ionization method (EI) performed under a normal pressure reduction, ions generated by only one-step ionization corresponding to the primary ionization are detected, so that the amount of target impurity ions X ⁺ is small and high sensitivity. It is difficult to detect. On the other hand, in the atmospheric pressure ionization method, the following secondary ionization is used to increase X ⁺ . That is, among the ions generated by the primary ionization, C ⁺ is an ion that is unnecessary for the purpose of analysis. In this method, the unnecessary ions C ⁺ find almost all the remaining impurities X that are not yet ionized, and transfer charges by a charge exchange reaction. This ion-molecule reaction is a reaction in which charges are transferred from one having a high ionization potential to one having a low ionization potential. Since carrier gas (nitrogen, argon, hydrogen, etc.) has a higher ionization potential than impurity molecules (H ₂ O, O ₂ , CO ₂ , organic matter, etc.), high sensitivity analysis of impurities becomes possible.

  APIMS is not easily affected by flowing a large amount of argon or nitrogen gas as a carrier gas. Therefore, by flowing a large amount of carrier gas, gas retention inside the plastic container can be suppressed, and the permeated measurement target gas can be immediately transported to the detector. Thereby, the response speed of detection can be increased, and detection in almost real time is possible. In addition, the waiting time until the gas concentration inside the container reaches a steady state can be shortened. In addition, if the amount of carrier gas is increased, the concentration (partial pressure) of the permeated gas to be measured is inevitably lowered, so that a detection method capable of analyzing a trace amount is required. For the above reasons, there is a need for a technique that does not decrease the detection accuracy even when a large amount of carrier gas such as APIMS is flowed and that can perform a trace analysis.

  As described above, the gas barrier property of the plastic molded body including the container can be measured with high accuracy and high speed by the combination of the drying process and the atmospheric pressure ionization analyzer.

  In the oxygen barrier property measuring apparatus represented by CONTROL-OL, which is shown in Patent Document 1, represented by OX-TRANTWIN, the measurement accuracy decreases when a large amount of carrier gas is flowed. The carrier gas flow rate can be up to 50 ml / min, but it is often measured at about 10 ml / min. On the other hand, in the measurement method according to the present embodiment, the flow rate per minute of argon gas supplied to the argon atmosphere side in the atmosphere adjustment step and the measurement target gas measurement step is preferably at least twice the capacity of the plastic container. For example, in a container having a capacity of 350 ml, the carrier gas flow rate can be set to a maximum of 2000 ml / min, and the measurement is performed at about 500 to 1000 ml / min. As described above, since the carrier gas (purge gas) can be flowed about 50 to 100 times more in the measurement method according to the present embodiment than the measurement method used in Patent Document 1, a steady state is achieved at an early stage. be able to. In particular, when evaluating the gas barrier property of a plastic container having a complicated three-dimensional shape, gas replacement inside the container can be suppressed and gas replacement can be performed quickly. Even in the oxygen barrier property measuring apparatus described in Patent Document 1, it is possible to quickly reach a stable state by removing the influence of moisture by providing a drying step. Therefore, the gas analyzer in the gas barrier measuring method according to the present invention includes the oxygen barrier property measuring apparatus described in Patent Document 1.

  In addition, since the gas permeability coefficient in a plastic has temperature dependency and humidity dependency, it is necessary to measure in a constant temperature state.

  For example, as shown in FIGS. 1 and 2, a plurality of coating chambers for coating a gas barrier thin film are disposed on one or both of the inner surface and the outer surface of a plastic container, and the coating chambers are operated simultaneously or sequentially. The gas barrier property measuring method for a plastic molded body according to this embodiment can be applied to a gas barrier property plastic container manufactured by a mass production machine that performs mass production coating. That is, every time a predetermined number of films are formed in each coating chamber, the drying process, the atmosphere adjustment process, and the measurement target gas measurement process are performed, and then the gas barrier properties of the gas barrier plastic container are compared for each coating chamber, resulting in poor operation of the coating chamber. A chamber operation determining step for determining

  FIG. 1 shows that a plurality of coating chambers (film formation chambers) are arranged on a circle-shaped turntable, and a gas barrier thin film is formed on one or both of the inner surface and the outer surface of the plastic container during one turn of the turntable. It is a conceptual diagram which shows the structure of the coating apparatus which coats. FIG. 2 is a conceptual diagram showing the steps corresponding to the arrangement of the coating chamber and the rotational position. The symbols A and B attached to the coating chamber indicate the type of the high-frequency power source, and the high-frequency power source A (not shown) and the high-frequency power source B (not shown) sequentially supply a high frequency to the coating chamber.

  Here, every time a predetermined number of films are formed for each coating chamber, a drying process, an atmosphere adjustment process, and a measurement target gas measurement process are performed. Focus on a single coating chamber arranged in a circle. For example, the film forming apparatus shown in FIG. 1 forms a gas barrier thin film every time the circle makes one rotation. However, every time the film is formed 100 times (each time the circle makes 100 rotations), the plastic container is taken out and the plastic is removed. The gas barrier property of the container is measured by the measurement method according to the present embodiment described above. The same applies to another coating chamber. The proportion of sampling is appropriately determined according to the production speed of the mass production machine. Next, the gas barrier properties of the gas barrier plastic container are compared for each coating chamber. If there is a container whose gas barrier property is lower than the average value of the gas barrier property of each container, it is estimated that the coating chamber corresponding to the container is inoperative, and the coating chamber is judged to be inoperative. In such cases, gas barrier thin film coated plastic containers that have been deposited in a poorly operated coating chamber are likely to be of poor quality due to their gas barrier properties, so they should be extracted from mass-produced gas barrier thin film coated plastic containers. You may confirm quality, such as measuring a gas barrier separately. In addition, if only the quality of each coating chamber is determined, the gas permeation amount may be measured before the gas permeation amount is completely stabilized. In this case, it is preferable to unify the measurement conditions. .

  Next, before describing a specific gas barrier property measurement procedure of the present embodiment, an embodiment of a gas barrier property measurement apparatus for performing this measurement method will be described. This apparatus is shown for explaining the measuring method, and the measuring method is not limited to this apparatus configuration.

  In FIG. 3, the schematic block diagram which shows one form of the gas barrier property measuring apparatus of a plastic container was shown. The piping configuration of this apparatus is a liquid argon tank 1, a liquid argon evaporator 2, a pressure reducing valve 3, and a getter 4 (manufactured by Japan API, GT100) for removing impurities such as water molecules, followed by a getter. 4 and the bypass line 5 and the container (for example, PET bottle) line 8 branched in parallel downstream, and after the bypass line 5 and the container line 8 merge again, the purifier 14 (manufactured by Nippon API Co., Ltd., MS- 10J), impurities are removed, and the measurement target gas is detected by APIMS15 (UG-240PN manufactured by Hitachi Tokyo Electronics Co., Ltd.).

  The bypass line 5 is connected by piping in the order of the mass flow controller 6 and the purifier 7, and the container line 8 is connected by piping in the order of the mass flow controller 9, the purifier 10, the internal space of the container 11, the valve B12, and the valve A13. ing. A gas supply pipe 16 and a gas discharge pipe 17 are inserted into the container 11 so that gas is introduced into the container 11 from the mouth and gas is again discharged from the mouth.

Further, in order to adjust the atmosphere outside the container 11, a pure air cylinder 21 or a standard gas cylinder 21 (for example, Ar (99%)-H ₂ (1%)), a pressure reducing valve 22, a mass flow controller 23, and FIG. The container external atmosphere adjustment means 31 connected by piping in the order of the chamber 24 for storing the container shown in the figure is prepared. Here, pure air or standard gas is introduced into the interior of the chamber 24 (the first space 106 in FIG. 4) so as to touch the outer surface of the accommodated container.

When the container is accommodated in the chamber 24 that accommodates the container separately illustrated in FIG. 4 and the container external atmosphere adjustment means 31 is operated to set the external atmosphere of the container to Ar (99%)-H ₂ (1%), for example, Hydrogen as a measurement target gas diffuses and permeates from the outer surface of the container toward the inner surface. Subsequently, hydrogen that has permeated the inside of the container using argon flowing through the container line 8 as a carrier gas is carried out of the container, and the APIMS 15 is used to detect the hydrogen concentration in the argon. Alternatively, when the external atmosphere of the container separately illustrated in FIG. 4 is pure air, for example, oxygen as the measurement target gas diffuses and permeates from the outer surface to the inner surface of the container and permeates. Subsequently, oxygen passing through the container line 8 to the inside of the container using argon as a carrier gas is carried out of the container, and the oxygen concentration in the argon is detected using the APIMS 15.

  Here, the chamber 24 will be described in detail with reference to FIG. FIG. 4 is a schematic view showing one embodiment of the chamber. The chamber 24 is composed of the accommodating portion 103 of the container 11 and the lid 104, and forms a sealed container. The nozzle 108 suspended from the lid 104 is a jig that separates the first space 106 (outside the container) and the second space 107 (inside the container). That is, the diameter of the nozzle 108 is substantially the same as the inner diameter of the mouth portion of the container 11, and the first space 106 and the second space 107 are separated by fitting the nozzle 108 in close contact with the mouth portion of the container 11. . The nozzle (jig) 108 has a pipe line 16 for introducing the carrier gas into the container 11, a pipe line 17 for discharging the carrier gas containing the measurement target gas pushed out from the container, and the container 11 mouths are sealed.

  In order to dry the PET bottle, a low-pressure mercury lamp 123 may be inserted from the mouth of the container 11 as shown in FIG. At this time, after the drying of the low-pressure mercury lamp 123 to the inner surface of the container 11 by ultraviolet irradiation, the ultraviolet generator-nozzle arrangement switching means (not shown) is attached so that the nozzle 108 fits closely to the mouth of the container 11. ) Is preferably provided. Further, a heater 122 may be provided for heating and drying.

Based on the apparatus shown in FIG. 3, the 1st operation procedure of the gas-barrier property measuring method which concerns on this embodiment is demonstrated.
(1) Background measurement With the mass flow controller 6, the background data is measured by flowing argon gas as a carrier gas at a rate of 1 liter per minute (flowing to the bypass line 5). At this time, the valve A13 is closed.
(2) Baking of container Baking of the container (for example, PET bottle) 11 is performed during (1). For example, the entire container is heated by being wrapped in a heat conductor such as aluminum foil. The mass flow controller 9 causes argon gas to flow through the container 11 at a rate of 1 liter per minute. In the case of a heat-resistant PET bottle, baking is performed at 80 ° C. for 30 minutes. At this time, the valve B12 is opened to exhaust the gas. In addition, when flowing gas into the container 11, one of the valves A13 and B12 must be opened. Further, the drying is performed by irradiating the plastic molded body (container) with ultraviolet rays as shown in FIG. Note that heating and drying such as heating the container with a heater or blowing hot air into the heating chamber and blowing the hot air may be performed simultaneously with or before or after the irradiation with ultraviolet rays. Any device can be used as long as it can heat the container as much as possible without causing thermal deterioration or deformation of the container. Only heat drying may be performed.
(3) Analysis in container line After finishing the drying process, the pulp B12 is closed, the pulp A13 is opened, the gas of the mass flow controller 6 (bypass line 5) is stopped, and the analysis in the container line 8 is started. At this time, pure air is allowed to flow from the pure air cylinder 21 into the first space 106 separately shown in FIG. 4, and analysis is performed for a predetermined time, for example, 1 hour in this state.
(4) Analysis in a container line (standard gas: Ar (99%)-H ₂ (1%) atmosphere)
A standard gas (Ar (99%)-H ₂ (1%)) is flowed through the first space 106 at a rate of 500 cc per minute by the mass flow controller 23 and analyzed for a predetermined time, for example, 1 hour.

  Next, another embodiment of the gas barrier property measuring apparatus having the drying means according to this embodiment will be described. A gas barrier property measuring apparatus 100 shown in FIG. 6 includes a gas analysis unit 101 such as a mass spectrometer, a chamber 105 that houses a plastic molded body 102 such as a plastic container, a plastic sheet, or a plastic film, and a plastic in the chamber 105. A jig 108 that separates a first space 106 that contacts one surface of the molded body 102 and a second space 107 that contacts the other surface, a measurement target gas supply unit 109 that supplies a measurement target gas to the first space 106, and The carrier gas supply unit 110 that supplies a carrier gas for transporting the measurement target gas that has passed through the plastic molded body from the first space 106 and reached the second space 107 to the gas analyzing unit 101, and the plastic molded body 102 are dried. Drying means. The measurement object gas supply unit 109 corresponds to the standard gas cylinder 21, the pressure reducing valve 22, and the mass flow controller 23 in the case of FIG. The plastic molded body 102 will be described as a plastic container (hereinafter referred to as a container).

The gas analyzer 101 is a gas analyzer such as a mass spectrometer or APIMS. The chamber 105 has the same configuration as the chamber 24 shown in FIG. In other words, the container 102 is composed of the accommodating portion 103 and the lid 104 to form a sealed container. The jig 108 is a nozzle 108 suspended from the lid 104. The diameter of the nozzle 108 is almost the same as the inner diameter of the mouth portion of the container 102, and the first space 106 (outside the container) and the second space 107 (inside the container) are fitted by closely fitting the nozzle 108 with the mouth portion of the container 102. ). The jig 108 has a conduit for introducing a carrier gas or a pretreatment gas (that is, a discharge gas) into the container 102, and a conduit for discharging the carrier gas containing the measurement target gas pushed out from the container 102. And the mouth of the container 102 is sealed. The measurement target gas supply unit 109 is, for example, a pure air cylinder when measuring oxygen permeability. When measuring the hydrogen permeability, for example, a standard gas cylinder (for example, Ar (99%)-H ₂ (1%)) is used. The gas barrier property measuring apparatus 100 has a configuration capable of measuring oxygen in pure air or hydrogen in a standard gas that permeates from the outside to the inside of the container 102.

  The gas barrier property measuring apparatus 100 is an example of an apparatus provided with a discharge cleaner as a drying means, and has a pretreatment gas supply means 111 for supplying a pretreatment gas for discharge cleaning to the second space 107. The pretreatment gas is guided to the second space through the lid 104 and the nozzle 108. A magnetron 112 for converting the pretreatment gas supplied into the second space 107 into plasma and a magnetron power supply 113 connected to the magnetron 112 are installed under the chamber 105 via a waveguide 114. The magnetron 112 that is supplied with power from the magnetron power supply 113 emits microwaves, turns the pretreatment gas inside the container into plasma through the waveguide, performs discharge cleaning, and the container 102 is dried. Valves 116, 117, 118, 119, 120, and 121 are installed in the piping in order to control the direction of gas flow in the piping.

  Since the gas barrier property measuring apparatus 100 incorporates a discharge cleaner composed of a magnetron 112 and a magnetron power supply 113, the first space 106 is used for the purpose of adjusting the pressure in the first space 106 and the second space 107 so as to easily cause discharge. And a vacuum pump 115 for evacuating either one or both of the second space 107.

  The housing portion 103 is provided with a heater 122 so that the container 102 can be heated from the surroundings. Thereby, since drying by heating can be performed in addition to discharge cleaning, drying of the container 102 is promoted. Examples of the means for heating the plastic molded body include a heater (not shown) and the like that puts the molded body into a heating chamber and blows hot air in addition to a heater heater. Any apparatus can be used as long as the apparatus can heat the plastic molded body as much as possible without causing thermal deterioration and deformation.

  Here, the gas barrier property measuring apparatus 100 may be provided with only the heater 122 as a drying means by heating. In this case, the drying means is only heat drying.

  Further, the gas barrier property measuring apparatus 100 may be provided with only the vacuum pump 115 as a drying means using vacuum. In this case, the drying means is only vacuum drying.

A second operation procedure of the gas barrier property measuring method according to the present embodiment will be described based on the apparatus shown in FIG.
(1-1) Container baking (first form)
After the container (for example, PET bottle) 102 is accommodated in the chamber 105, the valves 116, 117, 118, and 121 are closed. Further, the valves 119 and 120 are opened. As a result, both the first space 106 and the second space 107 are decompressed. By placing the container 102 in a vacuum atmosphere for a predetermined time, the container 102 is vacuum-dried. At this time, the heater 122 may be operated to heat at a temperature that does not deform the container.
(1-2) Baking containers (second form)
After the container (for example, PET bottle) 102 is accommodated in the chamber 105, the valves 116, 117, 118, and 121 are closed. Further, the valves 119 and 120 are opened. As a result, both the first space 106 and the second space 107 are decompressed. Next, the valve 116 is opened and a pretreatment gas such as helium gas is supplied to the second space. The magnetron power supply 113 is turned on, microwaves are generated from the magnetron 112, and the pretreatment gas is turned into plasma. Thereby, the inner surface of the container 102 is discharged and washed, and at the same time, the container 102 is dried. At this time, the heater 122 may be operated to heat at a temperature that does not deform the container.
(2) Analysis After the drying process is completed, the valve 117 is opened and the carrier gas is supplied into the second space 107. The valve 109 is opened to supply pure air or standard gas into the first space 106. The valve 119 and the valve 120 are closed, and the valve 121 is opened. Thereby, oxygen of pure air in the first space 106 or hydrogen of the standard gas permeates from the outer surface of the container 102 toward the inner surface, and the oxygen or hydrogen that has permeated to the second space 107 is transmitted to the gas analysis unit 101 by the carrier gas. Carried to. In this state, analysis is performed for a predetermined time, for example, 1 hour. Conditions such as the gas type and flow rate of the carrier gas are the same as those in FIG.

  The above description is for explaining the measurement procedure, and the combinations shown in Table 1 may be used as the standard gas.

Example 1
In the examples, a heat-resistant round PET bottle having a height of 157 mm, a barrel diameter of 68 mm, a diameter of 28 mm, a wall thickness of 0.35 mm, a capacity of 350 ml, and a surface area of 320 cm ² was used as a measurement container. As a measuring instrument, an apparatus having the gas system shown in FIG. APIMS (UG-240PN manufactured by Hitachi Tokyo Electronics Co., Ltd.) was used as a detector for the gas to be measured. The measurement was performed according to the first operation procedure (1), (2), and (3) of the gas barrier property measuring method according to the present embodiment. Example 1 was set when the atmosphere outside the container was made pure air (atmosphere) by the pure air cylinder 21.

(Example 2)
Following the first example, the first operation procedure (4) of the gas barrier property measuring method according to the present embodiment is performed, and the atmosphere outside the container is set to the standard gas: Ar (99%)-H ₂ (1%) atmosphere by the standard gas cylinder 21. Example 2 was taken as Example 2.

  FIG. 7 shows changes in oxygen concentration and hydrogen concentration with respect to measurement elapsed time for Examples 1 and 2. Further, FIG. 8 shows the relationship between the mass number and the ion intensity at the time of background measurement in the first operation procedure (1) of the gas barrier property measuring method. The relationship between the mass number and the ionic strength at the time of measuring the oxygen concentration in Example 1 is shown in FIG. The relationship between the mass number and the ionic strength at the time of measuring the hydrogen concentration in Example 2 is shown in FIG.

(Examples 3 and 4)
A container to be measured was obtained by uniformly forming a DLC film with a thickness of 9 nm on the inner surface of the same heat-resistant round PET bottle as in Example 1 (film formation time: 0.9 seconds). At this time, the output of the high-frequency power supplied to the film formation in the same high-frequency plasma CVD apparatus as in Patent Document 1 was set to 500 W. The measurement is performed in the same manner as in Examples 1 and 2, and when the atmosphere outside the container is pure air (atmospheric atmosphere) using a pure air cylinder 21, Example 3 is used, and the atmosphere outside the container is standard gas: Ar (99%). Example 4 was set when the atmosphere was —H ₂ (1%).

  FIG. 11 shows changes in oxygen concentration and hydrogen concentration with respect to measurement elapsed time for Examples 3 and 4. Further, FIG. 12 shows the relationship between the mass number and the ion intensity at the time of background measurement in the first operation procedure (1) of the gas barrier property measuring method. The relationship between the mass number and the ionic strength at the time of measuring the oxygen concentration in Example 3 is shown in FIG. The relationship between the mass number and the ionic strength at the time of measuring the hydrogen concentration in Example 4 is shown in FIG.

(Examples 5 and 6)
A container to be measured was obtained by uniformly forming a DLC film with a thickness of 14 nm on the inner surface of the same heat-resistant round PET bottle as in Example 1 (film formation time: 1.4 seconds). The film forming conditions were the same as those in Examples 3 and 4. The measurement is performed in the same manner as in Examples 1 and 2, and when the atmosphere outside the container is pure air (atmospheric atmosphere), Example 5 is used. The atmosphere outside the container is set to standard gas: Ar (99%) by a standard gas cylinder 21. Example 6 was set when the atmosphere was H ₂ (1%).

(Examples 7 and 8)
A container to be measured was obtained by uniformly forming a DLC film with a thickness of 19 nm on the inner surface of the same heat-resistant round PET bottle as in Example 1 (deposition time 1.9 seconds). The film forming conditions were the same as those in Examples 3 and 4. The measurement is performed in the same manner as in Examples 1 and 2, and when the atmosphere outside the container is pure air (atmosphere) by the pure air cylinder 21, Example 7 is used, and the atmosphere outside the container is standard gas: Ar (99%). Example 8 was set when the atmosphere was —H ₂ (1%).

(Examples 9 and 10)
A container to be measured was obtained by uniformly forming a DLC film with a thickness of 24 nm on the inner surface of Example 1 and a heat-resistant round PET bottle (film formation time 2.4 seconds). The film forming conditions were the same as those in Examples 3 and 4. The measurement is performed in the same manner as in Examples 1 and 2, and when the atmosphere outside the container is pure air (atmospheric atmosphere) using the pure air cylinder 21, Example 9 is used, and the atmosphere outside the container is set using the standard gas cylinder 21 as a standard gas: Ar. Example 10 was set when the atmosphere was (99%)-H ₂ (1%).

Table 3 shows the results of measuring oxygen and hydrogen permeation amounts for Examples 1 to 10. After stabilizing the permeation amount, the permeation amount (ng) for 13 minutes was quantified. Based on this quantitative value, the permeation amount (cc / day / kg) per container was calculated. FIG. 15 shows the relationship between the thickness of the DLC film and the oxygen permeation amount, and FIG. 16 shows the relationship between the thickness of the DLC film and the hydrogen permeation amount. Note that pkg is an abbreviation for Package.

  As can be seen from the results of Table 3, FIG. 15 and FIG. 16, the relationship that the gas permeation amount decreases as the film thickness increases was clarified, and the oxygen barrier property and the hydrogen barrier property could be evaluated. At this time, referring to FIG. 7 as an example, it takes about 1.5 hours from the drying step to the end of the oxygen barrier property measurement, and then 2.5 hours as the total measurement time until the hydrogen barrier property measurement is continued. It was measurable in time. In Examples 1 to 10, for example, as is clear with reference to FIG. 7 or FIG. 9, the oxygen gas permeation amount or the hydrogen gas permeation amount can be measured in about 1.5 hours. When the permeation amount is continuously measured, the drying process can be omitted once, so that the evaluation can be performed in 2.5 hours.

  In Examples 1-10, although the method of measuring oxygen gas and hydrogen gas was shown, by adjusting the atmosphere outside the container using the standard gas shown in Table 1, carbon dioxide gas or oxygen gas (mass number 18) The gas permeation amount can be measured in a short time as in the example.

(Examples 11 to 15 and Comparative Example 1)
The time until the oxygen concentration is stabilized is compared by examining the change in the oxygen concentration in the carrier gas flowing into the PET container when the drying is performed and when the drying is not performed. A PET container is a container with high hygroscopicity. Evaluation was performed using the same container as in Example 1. The case where the plastic container was not dried was designated as Comparative Example 1. A case where a plastic container was dried in a vacuum of 2 Pa for 2 hours according to the second operation procedure (1-1) (2) before analysis was defined as Example 11. Example 12 was the case where the plastic container was dried by ultraviolet irradiation for 2 hours according to the first operation procedure (2) before analysis. A case where the plastic container was dried by heating in a vacuum of 2 Pa for 1 hour and then heating at 60 ° C. for 1 hour in accordance with the second operating procedure (1-1) (2) before analysis was taken as Example 13. Example 14 shows a case where the plastic container was irradiated with ultraviolet rays for 1 hour according to the first operating procedure (2) before analysis and then dried by heating at 60 ° C. for 1 hour. A case where the plastic container was dried at 60 ° C. for 2 hours according to the case of only heating in the first operation procedure (2) before analysis was defined as Example 15. In Examples 11 to 15, argon gas was allowed to flow inside the container at a flow rate of 1000 ml / min during drying. The outside of the container was an air atmosphere. The results are shown in FIG. FIG. 18 is a graph showing changes in the oxygen concentration in the carrier gas flowing through the PET container. As is clear from FIG. 18, in Examples 11 and 13 to 15, the oxygen concentration was almost constant from the start of measurement (when the elapsed time was 3 hours in the figure). The oxygen concentration becomes substantially constant after 4 hours from the start (when the elapsed time is 3 hours in the figure). Therefore, in Examples 11-15, it is possible to evaluate oxygen permeability immediately after the drying step. On the other hand, in Comparative Example 1, the oxygen concentration gradually decreases with time. Although not shown in FIG. 18, the oxygen concentration finally reached approximately 40 ppb when the elapsed time was 38 hours. Therefore, the time required to start the measurement is clearly shorter in Examples 11 to 15 after the drying process. Therefore, the effect of having a drying process became clear.

(Comparative Example 2)
A heat-resistant round PET bottle (uncoated bottle) similar to that in Example 1 was used as a measurement container. Instead of performing the drying step of the first operation procedure (2) of the gas barrier property measuring method according to this embodiment, argon is flowed at a flow rate of 1 liter / min for 10 hours without heating, and then the oxygen concentration is measured. This was designated as Comparative Example 2.

  In Comparative Example 2, the value was finally stabilized by flowing argon at 1000 cc / min for 10 hours. Compared to Example 1, it took time for drying to remove water molecules, and rapid measurement was impossible.

(Comparative Examples 3, 4, 5, 6 and 7)
Uncoated plastic container measured in Examples 1 and 2, coated plastic container with a deposition time of 0.9 seconds measured in Examples 3 and 4, coating with a deposition time of 1.4 seconds measured in Examples 5 and 6 A plastic container, a coating plastic container with a film formation time of 1.9 seconds measured in Examples 7 and 8, and a coating plastic container with a film formation time of 2.4 seconds measured in Examples 9 and 10, manufactured by Mocon, OX- Using TRAN2 / 21, the amount of oxygen permeation (cc / day / kg) was measured with the inside of the container being 23 ° C.-55% RH, the outside of the container being 23 ° C.-100% RH, and the oxygen partial pressure being 21%. As shown in Table 4, Comparative Example 3, Comparative Example 4, Comparative Example 5, Comparative Example 6, and Comparative Example 7 were used in this order. The measurement time was measured after 1 day, 2 days, 3 days, 4 days, 5 days, and 6 days. The results are shown in Table 5.

  About Comparative Examples 3-7, the relationship between measurement elapsed time and oxygen permeation amount was shown in FIG. In Comparative Examples 3 to 7, a drying process is not provided, and a large amount of argon gas that is a carrier gas cannot be flowed. At this time, it takes a long time for the measurement data to stabilize. It is assumed that water molecules are removed during this long period of time and that the inside of the container is replaced with gas. As apparent from FIG. 17, it takes about 5 to 6 days for the oxygen transmission rate to stabilize. It can be seen that in Examples 1, 3, 5, 7, and 9, it takes much time to evaluate the oxygen permeation amount after 1.5 hours from the start of measurement.

It is a conceptual block diagram which shows one form of the coating apparatus of a mass production machine. It is a conceptual diagram which shows one form of the coating chamber arrangement | positioning of a coating apparatus. It is a schematic block diagram which shows one form of the gas barrier property measuring apparatus of a plastic container. It is the schematic which shows one form of the internal structure of the chamber of a plastic container. It is the schematic which shows one form of arrangement | positioning of an ultraviolet generator, when irradiating an ultraviolet-ray inside a plastic container. It is a schematic block diagram which shows another form of the gas barrier property measuring apparatus of a plastic container. It is a figure which shows the change of the oxygen gas concentration by the measurement elapsed time and hydrogen gas concentration about Example 1 and 2. FIG. It is a figure which shows the relationship between the mass number at the time of the background measurement of the operation procedure (1) of the gas-barrier measuring method about Example 1 and 2, and ion intensity. It is a figure which shows the relationship between the mass number at the time of the oxygen gas concentration measurement of Example 1, and ionic strength. It is a figure which shows the relationship between the mass number at the time of the hydrogen gas concentration measurement of Example 2, and ionic strength. It is a figure which shows the change of the oxygen gas concentration by the measurement elapsed time and hydrogen gas concentration about Example 3 and 4. FIG. It is a figure which shows the relationship between the mass number at the time of the background measurement of the 1st operation procedure (1) of the gas-barrier property measuring method about Example 3 and 4, and ion intensity. It is a figure which shows the relationship between the mass number at the time of the oxygen gas concentration measurement of Example 3, and ionic strength. It is a figure which shows the relationship between the mass number at the time of the hydrogen gas concentration measurement of Example 4, and ionic strength. It is a figure which shows the relationship between the film thickness of a DLC film, and oxygen gas permeation amount. It is a figure which shows the relationship between the film thickness of a DLC film | membrane, and hydrogen gas permeation amount. It is a figure which shows the relationship between the measurement days and the oxygen gas permeation amount at that time about Comparative Examples 3-7. It is a graph which shows the change of the oxygen concentration in the carrier gas passed through in a PET container.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid argon tank 2 Liquid argon evaporator 3,22 Pressure reducing valve 4 Getter 5 Bypass line 6,9,23 Mass flow controller 7,10,14 Purifier 8 Container line 11 Container 12 Valve B
13 Valve A
15 APIMS
16 Gas supply pipe 17 Gas exhaust pipe 21 Standard gas cylinder or pure air cylinder 24 Chamber 31 Container external atmosphere adjustment means 101 Gas analysis section 102 Plastic container 103 Housing section 104 Lid 105 Chamber 106 First space 107 Second space 108 Jig (nozzle )
109 Measurement object gas supply unit 110 Carrier gas supply unit 111 Pretreatment gas (discharge gas) supply means 112 Magnetron 113 Magnetron power supply 114 Waveguide 115 Vacuum pump 100 Gas barrier property measuring apparatus

Claims (20)

In the gas barrier property measuring method of measuring the permeation amount of the gas to be measured that permeates a plastic molded body such as a plastic container, a plastic sheet or a plastic film, by a gas analyzer,
A method for measuring a gas barrier property of a plastic molded body, comprising a step of reducing an impurity concentration of the plastic molded body.   The step of reducing the impurity concentration of the plastic molded body is to irradiate the plastic molded body with ultraviolet rays, place the plastic molded body in a reduced pressure atmosphere, or discharge and clean the plastic molded body The method for measuring a gas barrier property of a plastic molded body according to claim 1, further comprising a drying step of drying the plastic molded body by performing any one of the methods.   The method for measuring gas barrier properties of a plastic molded article according to claim 2, wherein the drying step includes heating the plastic molded article in a temperature range in which the plastic molded article is not deformed or thermally degraded.   An atmosphere adjustment in which one side of the wall surface of the plastic molded body is a measurement target gas-containing atmosphere, and the other side of the wall surface is a carrier gas atmosphere that transports the measurement target gas after transmission to the gas analyzer. The method for measuring gas barrier properties of a plastic molded article according to claim 1, 2 or 3, further comprising a step.   The method for measuring gas barrier properties of a plastic molded body according to claim 4, wherein the carrier gas atmosphere is an argon atmosphere or a nitrogen gas atmosphere. 5. The gas barrier property measuring method for a plastic molded body according to claim 4, wherein the drying step is simultaneously performed in the atmosphere adjustment step.   When the measurement target gas permeates the plastic molded body from one side of the wall surface to the other side and the permeation amount of the measurement target gas becomes almost steady, the permeation amount is measured by the gas analyzer. The method for measuring a gas barrier property of a plastic molded article according to claim 1, further comprising a measuring object gas measuring step.   The method for measuring a gas barrier property of a plastic molded body according to claim 2, wherein the drying step includes a step of removing moisture absorbed by the plastic molded body.   In the drying step, the adsorption gas adsorbed on one side of the wall surface of the plastic molded body is replaced with the gas in the atmosphere containing the measurement target gas, and is adsorbed on the other side of the wall surface of the plastic molded body. 9. The method for measuring a gas barrier property of a plastic molded article according to claim 2, comprising a step of replacing the adsorbed gas with a gas in the carrier gas atmosphere.   10. The gas barrier property measuring method for a plastic molded article according to claim 1, wherein the gas analyzer is a mass spectrometer.   The method for measuring a gas barrier property of a plastic molded article according to claim 10, wherein the mass spectrometer is an atmospheric pressure ionization mass spectrometer (APIMS).   The plastic molded body is a plastic container, or a gas barrier plastic container in which a gas barrier thin film is coated on one or both of the inner surface and the outer surface, and in the atmosphere adjustment step, the outside of the container is a gas to be measured. 12. The gas barrier property measuring method for a plastic molded article according to claim 4, wherein the atmosphere is contained and the inside of the container is the carrier gas atmosphere.   The measurement object gas is an oxygen gas, and the measurement object gas-containing atmosphere is an air atmosphere, wherein the measurement object gas-containing atmosphere is an air atmosphere. The gas barrier property measuring method of the plastic molding as described.   The measurement target gas is any one of oxygen gas, carbon dioxide gas, hydrogen gas, or a combination thereof, and the measurement target gas-containing atmosphere is adjusted so that the measurement target gas has a predetermined partial pressure. The plastic molded body according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, wherein the atmosphere is an argon atmosphere or a measurement object gas-nitrogen gas atmosphere. Gas barrier property measuring method.   The measurement target gas is an oxygen gas having a mass number of 18, and the measurement target gas-containing atmosphere is an oxygen gas-argon atmosphere having a mass number of 18 adjusted so that the oxygen gas having a mass number of 18 has a predetermined partial pressure. The gas barrier property of the plastic molded article according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, characterized by being an oxygen gas-nitrogen gas atmosphere having a mass number of 18. Measuring method.   The measurement target gas is a mixed gas of at least one of mass 16 oxygen gas, carbon dioxide gas or hydrogen gas and mass 18 oxygen gas, and the measurement target gas-containing atmosphere is the measurement target gas. Is a measurement target gas-argon atmosphere adjusted so as to have a predetermined partial pressure, or a measurement target gas-nitrogen gas atmosphere. A method for measuring gas barrier properties of a plastic molded article according to 8, 9, 10, 11 or 12.   The plastic container has a gas barrier property that is mass-produced by arranging a plurality of coating chambers for coating a gas barrier thin film on one or both of the inner surface and the outer surface of the plastic container and operating the coating chambers simultaneously or sequentially. Each time a predetermined number of films are formed for each coating chamber, the drying step, the atmosphere adjustment step, and the measurement target gas measurement step are performed, and then the gas barrier property of the gas barrier plastic container for each coating chamber And a chamber operation determining step for determining an operation failure of the coating chamber by comparing the coating chambers of the plastic molded body according to claim 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16. Gas barrier property measuring method.   In the atmosphere adjustment step or the measurement target gas measurement step, the argon flow rate per minute or the nitrogen flow rate per minute supplied to the carrier gas atmosphere side is at least twice the capacity of the plastic container. The gas barrier property measuring method for a plastic molded article according to claim 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 or 17. A gas analyzer,
A chamber for accommodating a plastic molded body such as a plastic container, a plastic sheet or a plastic film;
In the chamber, a jig that separates a first space in contact with one surface of the plastic molded body and a second space in contact with the other surface;
A measurement target gas supply unit for supplying a measurement target gas to the first space;
A carrier gas supply unit that supplies a carrier gas for transporting the measurement object gas that has passed through the plastic molded body from the first space and reached the second space to the gas analysis unit;
A gas barrier property measuring apparatus for a plastic molded body, comprising: a drying unit that dries the plastic molded body. The drying means includes an ultraviolet generator that irradiates the plastic molded body with ultraviolet rays, a vacuum pump that evacuates the interior of the chamber, a discharge generator that discharges and cleans the plastic molded body, or a heater that heats the plastic molded body. 20. The gas barrier property measuring apparatus for a plastic molded body according to claim 19, comprising at least one of the following.

Images