JP2015222190A - Immersion history estimation method of glass piece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an immersion history estimation method of a glass piece.SOLUTION: The estimation method of an immersion history of a glass piece of the present invention includes a process of evaluating a behavior of the electrification of a surface of the glass piece immersed in a liquid, and estimating the immersion history of the glass piece on the basis of the evaluation result. Preferably, the behavior of the electrification is one or more selected from the group consisting of the magnitude of the electrification, excitation power dependency, discharge time constant, temperature dependence of the magnitude of the electrification, and the temperature dependence of the discharge time constant. Preferably, the behavior of the electrification is evaluated using a photoelectron spectrometer.

Description

  The present invention relates to a method for estimating a dipping history, which is information relating to time, for a glass piece immersed in a liquid or a glass piece which is assumed to be immersed in a liquid but whose immersion fact has not been confirmed.

  There are some cases where it is necessary to estimate the immersion history such as the immersion period and the immersion period for the glass piece immersed in the liquid. For example, there are many accidents in which foreign substances are mixed in foods such as alcoholic beverages, drinking water, vinegar, soy sauce, sauces, dressings, and retort foods. There is a report that about 5% of the contaminants are glass pieces (Non-patent Document 1). In order to prevent the recurrence of a foreign matter accident and improve the safety of food, it is extremely important to identify the foreign matter contamination stage. In particular, there is a risk of causing injuries to glass pieces, and mixing requires eradication. For this reason, in the event of a glass piece mixing accident, it is important to be able to estimate the immersion history in the liquid. In addition, it is assumed that a piece of glass that has been crushed by some accident is scattered in pooled water, lake water, rivers, seawater, and it is necessary to estimate its immersion history.

  In Japan, where cleanliness is specifically required in the world, food manufacturing companies are paying close attention and taking various measures to prevent contamination by foreign substances in the manufacturing process. In spite of this, the number of complaints about foreign matter contamination in food has increased in recent years (Non-Patent Document 2). For this reason, the inspection method of the contaminated foreign matter has progressed and is considered to be well established. However, there is no method for estimating the immersion history of a glass piece immersed in the liquid.

  Conventional techniques used as foreign matter inspection include morphological observation with an optical microscope, identification of a substance with infrared spectroscopic analysis, elemental analysis with fluorescent X-ray analysis, and microstructural observation with an electron microscope (Non-patent Document 3). . In an analysis method (non-patent document 4) called photoelectron spectroscopy, which measures the energy spectrum of photoelectrons emitted from a sample irradiated with monochromatic light into a vacuum, the elements constituting the sample and their elements are determined from the peak position of the photoelectron spectrum. Since valence information can be obtained, it can be used for identification of unknown substances, so it is also effective as a method for inspecting contaminants. However, although these analysis methods are effective for specifying the composition of the adhered foreign matter, none of them gives information (immersion history) on the “time” during which the glass piece has been immersed in the liquid.

  Regarding the mixed resin piece, thermal deformation is detected by infrared spectroscopic analysis, and the thermal history of the resin heated to a temperature exceeding the thermal deformation temperature can be estimated (Patent Document 1). However, this analysis method cannot be applied to a glass piece or the like that has a very high heat distortion temperature and is unlikely to change as detected by infrared spectroscopic analysis. For this reason, there has been proposed a method of measuring the amount of fluorescence emitted from a glass piece while raising the temperature after irradiation with X-rays, ultraviolet rays, or the like (Patent Document 2). However, this analysis method provides only the heat history and does not provide information on the immersion time.

  Specifically, in Patent Document 2, the behavior of emission intensity due to heating was different between a glass piece that was heated for 121 minutes at 121 ° C. for the purpose of sterilization and a glass piece that was not heated, Examples are given, and certain information is given regarding the presence or absence of a history of heating to high temperatures. However, when heating to a similar temperature is performed a plurality of times over time, information on which glass piece has been mixed before heating is not given. For example, a glass piece that has been mixed at the stage of manufacture at the factory and sterilized at 100 ° C. for several minutes, and a food or foodstuff is put into a cooking container in which the glass piece has been mixed inadvertently by the consumer. With a few minutes of cooking, it cannot be distinguished from a glass piece to be immersed.

  Analyze the degree of penetration of food components into foreign bodies using any of X-ray fluorescence analysis, element concentration analysis, infrared absorption analysis, staining concentration analysis, and volatile component concentration analysis, which enables elemental analysis, etc. There has also been proposed a method for estimating the time during which foreign matter has been mixed in food (Patent Document 3). However, this method can be applied only to foreign substances, such as hair, wood chips, paper, plastics, insects, etc., through which food components penetrate, and not to metals or glass that do not penetrate food components.

  By the way, in soda lime glass which is the most commonly used glass material, the Na ion concentration is lower in the surface layer portion from the surface to a depth of several tens of nm than in the surface layer portion. (Non-patent Document 5). Further, it is known that silicon, which is a main component, is eluted in the liquid by immersing glass in the liquid (Non-patent Document 6).

  Further, regarding the above-described photoelectron spectroscopy, an EUPS apparatus has been developed as one of the photoelectron spectrometers (Non-patent Document 7). This EUPS apparatus is generally used as a photoelectron spectrometer, “XPS” excited by X-rays having a photon energy of 1 to 2 keV and “UPS” excited by UV light having a photon energy of 20 to 40 eV. Not have some features. For example, i) The photon energy of the excitation light is 255 eV, so that information on the outermost surface atomic layer of the sample can be obtained, and ii) the charging of the insulator can be evaluated with high accuracy.

Incorporated administrative agency National Life Center, "Such things are in", [online], March 28, 1997, [April 30, 2014 search], Internet <http://www.kokusen.go.jp /news/data/a_W_NEWS_034.html> Ikari Sanitization Co., Ltd., “Special feature: Professionals 2-1 Thinking and proceeding with comprehensive measures to prevent foreign substances in food manufacturing”, [online], [Search April 30, 2014], Internet <http: // www .ikari.co.jp / topics / professional6.html> Japan Food Analysis Center, “Foreign substance inspection guide”, [online], [Search April 30, 2014], Internet <http://www.jfrl.or.jp/item/abnormal/abnormal1. html> Stefan Hufner, `` Photoelectron Spectroscopy: Principles and Applications '' (Berlin), Springer, 2003 Toshio Suzuki, Tomomi Sekine, Daisuke Kobayashi, Yuichi Yamamoto, “Development of Glass Surface Analysis Technology”, “Asahi Glass Research Report”, Vol. 63, 2013, p.11 Hiroyuki Tsuchiya, “Characteristics of materials used in mini-file laboratory instruments”, [online], [searched April 30, 2014], Internet <http://www.jsac.or.jp/bunseki/pdf/bunseki2011/ 201101minifile.pdf> (Hiroyuki Tsuchiya, “Bunseki”, Vol.1, 2011, p.32) Toshihisa Tomie, Tomoaki Ishitsuka, Teruhisa Ootsuka, Hiroyuki Ota, `` Observation of Work Functions, Metallicity, Band Bending, Interfacial Dipoles by EUPS for Characterizing HighkMetal Interfaces '', AIP Conf Proc., 1395, 148, 2011

JP 2012-255692 A JP 2005-62107 A JP 2005-83804 A

  The subject of this invention is related with providing the immersion log | history estimation method of a glass piece. That is, the problem of the present invention relates to a glass piece that can be a foreign substance mixed in food, and does not try to detect food components that penetrate into the glass piece, but will occur when the glass piece is immersed in a liquid. It is to provide a method for estimating the immersion history such as the immersion period and immersion period of the glass piece by capturing the chemical reaction change in the glass surface layer.

  From the information disclosed in Non-Patent Documents 5 and 6, the present inventors have immersed the glass in a liquid, so that the surface of the glass including the surface of the glass has a very thin thickness on the order of nanometers. In addition to the known change of elution of Na ions in the glass into the liquid, the structural change of the glass molecules must have occurred. And the magnitude | size of the structural change and the site | part which a structural change generate | occur | produced differed with the kind of liquid which glass immerses, temperature, an immersion period, etc. Moreover, even if the glass molecular structure changes due to the immersion of the glass, the region where the structural change occurs is expected to be limited to the glass surface layer only. It is considered that the use of expensive equipment is essential. Therefore, the present inventors considered that an EUPS apparatus having the highest surface sensitivity among all analytical methods is appropriate as a means for observing the structural change of the glass.

  Based on such an idea, the present inventors analyzed the immersed glass pieces in detail with an EUPS apparatus, and as a result, obtained experimental data suggesting that the structural change of the glass molecules occurred as expected. The structural change was different depending on the immersion conditions of the glass pieces. Then, the present inventors have found that such knowledge can be applied to the analysis of the actual condition of mixing glass pieces as foreign substances in food. Patent Document 3 discloses a method for estimating the time during which a foreign substance has been mixed in food, but this method is a method for detecting a food component that penetrates into a foreign substance. This method is completely different from the method based on the found knowledge, that is, the method of detecting the change of the structure of the glass piece as a foreign substance without detecting food components and estimating the immersion history of the glass piece.

  The present invention has been made on the basis of the above knowledge, and has a step of evaluating the charging behavior of the surface of the glass piece immersed in the liquid and estimating the immersion history of the glass piece based on the evaluation result. It is the immersion history estimation method of a piece.

  Further, the present invention was made based on the above knowledge, and for the glass piece mixed as a foreign substance in food, applying the immersion history estimation method to estimate the mixing history of the glass piece into the food, This is a foreign matter contamination history estimation method.

  According to the glass piece immersion history estimation method of the present invention, information on the immersion history such as the immersion time and the immersion time of the glass piece can be obtained. This information can be applied as a method for estimating the mixing time and mixing period of glass pieces that have been mixed as foreign substances in foods such as sake and retort foods. The glass piece immersion history estimation method of the present invention is also applied as a method for estimating the immersion time and immersion period of glass pieces that have been crushed for some reason and scattered and immersed in pool water, lake water, rivers, seawater, etc. Furthermore, it can be expected to be applied as a method for estimating the exposure time and exposure period to various gas atmospheres including the atmosphere.

1 (a) to 1 (c) are photoelectron spectra of Si2p core levels of the glass piece obtained in Example 1, respectively, as “charging behavior” on the surface of the glass piece. It is a graph which shows "the magnitude | size of charging" and its "temperature dependence". FIG. 2 is a graph showing “excitation power dependence” and “temperature dependence” as “charging behavior” of the surface of the glass piece, obtained in Example 1, and the liquid in which the glass piece is immersed. It is a graph in case temperature is 100 degreeC and immersion time is 5 minutes. FIG. 3A and FIG. 3B are graphs showing “excitation power dependence” and “temperature dependence” as “charging behavior” of the surface of the glass piece obtained in Example 1, respectively. 3 (a) is a graph when the temperature of the liquid into which the glass piece is immersed is 100 ° C. and the immersion time is 1 hour, and FIG. 3 (b) is a temperature at which the liquid into which the glass piece is immersed is room temperature, It is a graph in the case of immersion time 11 days.

  In the glass piece immersion history estimation method of the present invention (hereinafter, also simply referred to as the immersion history estimation method), an evaluation object is a glass piece immersed in a liquid. The glass piece to which the present invention can be applied is a hard substance mainly composed of silicate, and the kind thereof is not particularly limited. For example, soda glass (soda lime glass, soda lime glass), crystal glass, borosilicate Glass etc. are mentioned. Further, the size of the glass piece is not particularly limited, and the glass piece to which the present invention can be applied is a glass piece having a size that can be mixed as a foreign substance in food sealed in a packaging container such as a can or a bag. Is included.

  The liquid in which the glass piece to be evaluated is immersed typically includes a “solution” in which two or more substances are diffusely mixed to form a uniform liquid phase. In the method, the kind of the liquid is not particularly limited, and may be one containing at least one substance having fluidity, and is a mixture of a liquid and a solid (a fluid in which a solid is dispersed in a liquid). It may be acidic, neutral or alkaline.

  In the immersion history estimation method of the present invention, the surface of the glass piece to be evaluated is charged. As a method of charging the surface of the glass piece, a known charging method can be used. For example, in addition to the method of irradiating the glass piece with light such as ultraviolet rays, X-rays, ion beams, electron beams, etc., discharge plasma The method of bathing is mentioned.

  In the immersion history estimation method of the present invention, after charging the surface of the glass piece to be evaluated, the charging behavior is evaluated. The “charging behavior” here is a characteristic relating to a charged state or charging. More specifically, “charging magnitude”, “excitation power dependence of charging magnitude”, “when charging is discharged” Constant ”,“ temperature dependence of charge magnitude ”, and“ temperature dependence of discharge time constant ”. With respect to the five “charging behaviors” listed here, the “charge behavior” at the time of photoexcitation is evaluated in the examples described later. Absent. In evaluating the “charging behavior” of the surface of the glass piece, all of these five may be evaluated, or a part of them may be evaluated. As these five “charging behavior” evaluation methods, known evaluation methods can be used. For example, surface potential measurement methods using various electric methods including a probe microscope can be used.

  Here, “excitation power dependence” and “temperature dependence” as “charging behavior” will be described. An insulator such as glass is a substance that does not allow electricity to flow, but has a finite resistance value. If it is left for a long time, the accumulated charge is lost. This phenomenon in which the accumulated charge is lost is referred to as “discharging” the charge. The difficulty of the flow of electricity greatly depends on the temperature. In general, the higher the temperature, the easier the flow of electricity and the shorter the discharge time constant. The charge amount increases as the charge supply rate increases, that is, the “excitation power” increases, and as the discharge speed increases, that is, as the discharge time constant decreases, the charge amount decreases. Therefore, the present invention provides, as an important evaluation method of “charging behavior”, “excitation power dependence” of charge magnitude and “time constant of discharge”, and “temperature dependence” of charge magnitude and discharge time constant. Presents a means to evaluate

  As a preferable embodiment of the immersion history estimation method of the present invention, there is an embodiment in which the “charge behavior” of the surface of the glass piece to be evaluated is evaluated using a photoelectron spectrometer (photoelectron spectroscopy). In photoelectron spectroscopy, a large amount of electrons are emitted outside the sample (glass piece) by irradiation with excitation light, so photoelectron spectroscopy can be used as a method for charging the glass piece. In photoelectron spectroscopy, the magnitude of charge (charge amount), which is an example of “behavior of charging”, can be evaluated from the magnitude of the shift of the peak position of the photoelectron spectrum. Can also be used as a method for evaluating the magnitude of charging. As the photoelectron spectroscopy, a known method called X-ray photoelectron spectroscopy (XPS) or ultraviolet photoelectron spectroscopy (UPS) can be used.

  However, in XPS and UPS, eliminating the influence of charging of an insulating sample such as a glass piece is one important apparatus technology, and quantitative evaluation of the charge amount on the surface of the glass piece is not easy. . According to the knowledge of the present inventors, a photoelectron spectroscopy suitable for evaluating the “charging behavior” of the surface of a glass piece is EUPS. That is, as a preferred embodiment of the immersion history estimation method of the present invention, there is an embodiment in which the “charging behavior” of the surface of the glass piece to be evaluated is performed using an EUPS apparatus that is a photoelectron spectrometer employing EUPS. . The EUPS device is a known photoelectron spectrometer that uses extreme ultraviolet (EUV) light as a light source, and is described in detail in Non-Patent Document 7, for example. In the EUPS device, the sample (glass piece) is irradiated with EUV light having a wavelength of 4.86 nm and a pulse width of 3 ns. By changing the repetition rate of the EUV light source, the average excitation power can be easily changed. In the EUPS apparatus, since the temperature (measurement temperature) of the carrier holding the sample (glass piece) can be changed, the sample temperature during measurement can be changed by appropriately changing the measurement temperature.

  In the immersion history estimation method of the present invention, after evaluating the “charge behavior” of the surface of the glass piece to be evaluated, the immersion history of the glass piece based on the evaluation result, more specifically the type of liquid, Estimate liquid temperature, immersion period, etc. `` Charging behavior '' varies depending on the type of glass constituting the glass piece to be evaluated, the type of liquid in which the glass piece was immersed, the liquid temperature, etc., so in order to correctly estimate the immersion history, A standard sample may be prepared separately from the glass piece. In other words, separately from the glass piece to be evaluated, a control glass piece (standard sample) having the same composition as the glass piece to be evaluated is prepared, and the “charging behavior” of the control glass piece and the glass piece to be evaluated is compared with each other. By doing, the immersion history of the glass piece of evaluation object can be estimated.

  As one embodiment of the immersion history estimation method using the control glass piece, a standard sample is obtained by immersing the control glass piece in the same composition liquid as the liquid in which the glass piece to be evaluated is immersed for a predetermined time. There is a method of estimating the immersion history of the glass piece to be evaluated by comparing the “charging behavior” of the sample and the glass piece to be evaluated. As this standard sample, a plurality of standard samples differing in any one or more of the kind of liquid in which the glass piece is immersed, the liquid temperature, and the immersion time can be prepared as necessary.

  In the immersion history estimation method using the control glass piece, “charge magnitude” may be focused on as “charge behavior”. That is, separately from the glass piece to be evaluated, a control glass piece having the same composition as that of the glass piece to be evaluated is prepared, and the charge amount of the surface is evaluated for each of the control glass piece and the glass piece to be evaluated, The immersion history of the glass pieces to be evaluated can also be estimated by comparing the values of the amounts with each other.

  According to the knowledge of the present inventors, the glass piece immersed in the liquid has a smaller surface charge (charge amount) than the glass piece that has never been immersed in the liquid. . As a method for estimating the immersion history of a glass piece based on this finding, a control glass piece having the same composition as the glass piece to be evaluated and never existing in the liquid, separately from the glass piece to be evaluated (hereinafter referred to as “no immersion control”). For example, a method of evaluating the charge amount of the surface of each of the non-immersed control glass piece and the glass piece to be evaluated and comparing the values of the charge amounts with each other can be exemplified. In this method, when the charge amount V1 of the glass piece to be evaluated is compared with the charge amount V2 of the non-immersed control glass piece, if the charge amount V1 is smaller than the charge amount V2, the glass piece to be evaluated is past. It can be presumed that they were present in the liquid.

  The method using the non-immersed control glass piece can be used, for example, to confirm whether or not the glass piece to be evaluated is mixed in the food after cooking with respect to the glass piece to be evaluated. it can. When a consumer or the like points out that a glass piece is mixed as a foreign substance in food, first, the “charged behavior” is compared between the glass piece to be evaluated and the non-immersed control glass piece. If the charging behavior of the glass piece to be evaluated matches that of the non-immersed control glass piece, it is determined at the consumer's stage that it has been mixed as a foreign substance in the food after cooking. If the glass piece to be evaluated shows a different “charging behavior” from the non-immersed control glass piece, then the control glass piece that has been heated for a short time in the target liquid, imitating cooking, is used. Prepare and compare it with the piece of glass to be evaluated. If the “charge behavior” of the two coincides, it is determined that the glass piece is mixed in the food for some reason after the food is opened, and the food is cooked in the mixed state. If it is determined in the above procedure that the glass piece to be evaluated has been mixed in the food before the food is opened, then the mixing stage is specified. While comparing the “charging behavior” of many control glass pieces produced under various immersion conditions with the “charging behavior” of the glass piece to be evaluated, the mixing stage is estimated and quality control in the factory is performed. Improvement will be achieved. For various control glass pieces such as the non-immersed control glass piece to be compared with the glass piece to be evaluated, the “charge behavior” is evaluated in advance, and data of the evaluation result is obtained. be able to. In this case, a database is obtained in which the “charging behavior” of multiple control glass pieces is stored. Therefore, the evaluation result of the “charging behavior” of the glass piece to be evaluated is checked against this database. It is possible to estimate the mixing history of the target glass piece into the food.

  The immersion history estimation method of the present invention estimates the contamination history (mixing time, mixing period, etc.) of the glass piece into the food for the glass piece mixed as a foreign matter in the food. Can be applied to. That is, the immersion history estimation method of the present invention can also evaluate a glass piece immersed in food. The food to which the present invention is applicable only needs to contain a liquid, and it does not matter whether heat treatment is performed. Specific examples of foods to which the present invention can be applied include retort products such as soup, pasta sauce, curry and stew, seasoning products such as dressing and mayonnaise, and beverage products such as tea, coffee and fruit drinks. it can.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, this invention is not restrict | limited by these Examples, such as a charging method, an evaluation method, an evaluation sample, immersion conditions.

[Example 1]
A commercially available 3 mm thick soda-lime glass plate is crushed, a plurality of glass pieces each having a side of about 10 mm are prepared, and the glass pieces are placed in a 0.1 M acetate buffer (pH 4.5) adjusted to a predetermined liquid temperature. For a predetermined time. After a predetermined soaking time, a glass piece was taken out from the acetate buffer, rinsed with ion-exchanged water, and further placed on a paper towel to remove moisture adhering to the glass piece and dried. The “charge behavior”, specifically “charge magnitude”, “excitation power dependence”, and “temperature dependence” of the surface of the glass piece thus dried were evaluated using an EUPS apparatus. As the temperature of the acetate buffer solution, two types of room temperature (about 20 ° C.) and 100 ° C. are prepared, and the immersion time of the glass piece is 11 days for room temperature immersion, 5 minutes and 1 hour for 100 ° C. immersion. Prepared.

  The reason why liquids having different temperatures were prepared as liquids for immersing glass pieces in Example 1 will be described. A known effect of chemical changes experienced by glass immersed in the liquid is the elution of Na ions contained in the glass into the liquid. In general, it is said that the rate of chemical change doubles when the temperature increases by 10 ° C. Assuming that the temperature dependence can be applied to the chemical change of the glass, if the temperature is different by 80 ° C., the chemical reaction rate is different to the power of 2 = 256 times. Soaking a glass piece in a liquid at room temperature for 11 days is equivalent to immersing the glass piece in a liquid having a liquid temperature of 100 ° C. for 1 hour. Compared with the immersion time of 5 minutes and 1 hour in the liquid at a liquid temperature of 100 ° C., the chemical reaction of the glass piece is expected to be 10 times different, and the glass piece immersed for 11 days in the liquid at room temperature. The experiment was conducted assuming that a glass piece immersed for 1 hour in a liquid having a liquid temperature of 100 ° C. would be equivalent. As shown below, the difference was clearly seen between the immersion time of 5 minutes and 1 hour, and the immersion for 11 days at room temperature and the immersion for 1 hour at 100 ° C. were not equivalent.

  The evaluation results of the “charging behavior” of the surface of the glass piece under each condition are shown in FIGS. The figure shows how to evaluate the magnitude of the charge on a glass piece using EUPS. FIG. 1 is a photoelectron spectrum of the Si2p core level of a glass piece. The horizontal axis is the kinetic energy of photoelectrons, and the vertical axis is the signal intensity. The repetition rate of the EUV light source was 10 Hz. In each of FIGS. 1 (a) to 1 (c), the graph indicated by symbol A is a glass piece obtained by immersing a glass piece in an acetic acid buffer solution at a liquid temperature of 100 ° C. for 5 minutes. This is a case where a glass piece is immersed in an acetic acid buffer solution at a temperature of 100 ° C. for 1 hour. Photoelectrons were observed with a deceleration of 130V. Since the photon energy of the excitation light is 255.2 eV and the work function of the measuring instrument is about 3.4 eV, the kinetic energy 17 eV corresponds to a binding energy of about 105 eV.

  As shown in FIG. 1 (a), when the measurement temperature, that is, the temperature of the carrier holding the sample (glass piece) in the EUPS apparatus is room temperature, the peak of the graph indicated by the symbol A is about 11.5 eV and indicated by the symbol B The peak of the graph was about 13 eV. On the other hand, when the measurement temperature is 55 ° C., the peak of the graph indicated by the symbol A is about 16.5 eV and the peak of the graph indicated by the symbol B is about 17.5 eV, as shown in FIG. When the measurement temperature was 100 ° C., the peak was about 17.5 eV in both the graph indicated by the symbol A and the graph indicated by the symbol B as shown in FIG. Although the peak positions are slightly different as originally expected, the peak position of the photoelectron spectrum of the Si2p core level increases as the measurement temperature increases for both samples A and B, and the amount of charge on the surface of the glass piece increases. It turns out that becomes small.

  As described above, when the measurement temperature is high, an insulator such as a glass piece becomes difficult to be charged. However, the fact that the surface of the glass piece is no longer charged can be determined by looking at the repetition rate (excitation power) dependence. . FIG. 2 shows “excitation power dependence” as “charging behavior” of the surface of the glass piece obtained in Example 1. This graph is a graph when the temperature of the acetate buffer solution is 100 ° C. and the immersion time is 5 minutes. The vertical axis in FIG. 2 is the peak position of the Si2p core level spectrum of the glass piece shown in FIG. The horizontal axis represents the repetition rate of excitation light (EUV light). The average excitation power of the EUV light that excites the sample is proportional to the repetition rate, and the 10 Hz measurement is five times the 2 Hz measurement. When the measurement temperature, that is, the temperature of the carrier holding the sample (glass piece) in the EUPS apparatus is room temperature, the peak position is 14.5 eV when the repetition rate of excitation light is 2 Hz, and the peak position is 11 when the repetition rate of excitation light is 5 Hz. When the repetition rate of excitation light is 5 eV and 10 Hz, the peak position is 8.5 eV, and there is a difference of 6 eV in the peak position between 2 Hz where the excitation power is small and 10 Hz where the excitation power is large, but when the measurement temperature is 55 ° C. The difference in peak position between 2 Hz and 10 Hz was significantly reduced to 1.5 eV. Even when the measurement temperature was 70 ° C., the difference in peak position between 2 Hz and 10 Hz was 1.5 eV. However, when the measurement temperature was 100 ° C., the peak positions of 2 Hz and 10 Hz almost coincided with each other. It can be determined that the surface of the glass piece is no longer charged at a temperature of ℃ or higher.

  FIG. 3 is a comparison of measurement results between a glass piece immersed for 1 hour at 100 ° C. and a glass piece immersed for 11 days at room temperature. In both cases, the magnitude of the chemical change was expected to be equivalent, but the charging behavior was very different. When the glass piece was immersed in an acetic acid buffer solution at a liquid temperature of 100 ° C. for 1 hour (FIG. 3A), when the measurement temperature was room temperature, the peak position was 10 eV when the excitation light repetition rate was 10 Hz. When the glass piece was immersed for 11 days in an acetate buffer having a temperature of room temperature (FIG. 3B), the peak position was 14.5 eV. In FIG. 3 (a), there was a clear dependence on the repetition rate (excitation power) even at a measurement temperature of 55 ° C., but in FIG. 3 (b), almost no dependence on the repetition rate was observed, and the surface of the glass piece. Became almost uncharged.

  Comparing FIG. 2 and FIG. 3 (a), it can be seen that the charging behavior differs depending on whether the time for immersing the glass piece in the 100 ° C. acetate buffer is 5 minutes or 1 hour. In other words, when the measurement temperature is room temperature, the immersion time is 5 minutes (FIG. 2), 14.5 eV in the case of 2 Hz excitation, and 8.5 eV in the case of 10 Hz, but the immersion time is 1 hour (FIG. 3 (a)). Then, it was 16 eV in the case of 2 Hz excitation and 10 eV in the case of 10 Hz.

  Here, the difference in influence on the sample (glass piece) between the temperature at the time of charging evaluation and the temperature of the liquid at the time of liquid immersion will be described. Elution of Na ions, which are constituent elements of glass, into the liquid occurs when the glass piece is immersed in the liquid. Since the EUPS evaluation of the charging behavior of the glass is performed in a vacuum, it is unlikely that Na ions will come out of the glass even if the temperature of the glass is raised. However, it is conceivable that Na ions move on the surface and inside of the glass by raising the temperature for measurement. As a result, the measurement history may be reflected in the charging behavior. This change is irreversible and temperature-dependent measurements can be one-time. And “heating in vacuum” for measurement may affect “structural change” of the glass piece surface caused by the history of “immersion in liquid”. In order to verify these possibilities, the measurements shown in FIGS. 2 and 3 are first measured at room temperature, then the temperature is gradually increased to 100 ° C., and then again at room temperature. As a result of the measurement, the same result as the first was obtained. That is, the influence of the temperature history in the “in-vacuum” measurement for evaluating the “charge behavior” on the “charge behavior” was not significant. On the other hand, it is considered that Na ions immersed in the liquid and once eluted in the liquid do not return to the glass. It is considered that the temperature history during immersion does not disappear.

  From the results shown in FIG. 1 to FIG. 3, due to the difference in the immersion time of the glass piece in the liquid, the “charge behavior” of the surface of the glass piece, more specifically, the magnitude of the charge and the excitation power dependence It is remarkably different, and it can be seen that the immersion condition of the glass piece can be estimated by evaluating and measuring this.

[Example 2]
A commercially available 3 mm thick soda-lime glass plate was crushed, and a plurality of glass pieces each having a side of about 10 mm were prepared. A 0.1 M acetate buffer solution (pH 4.5) was heated to adjust the solution temperature to 100 ° C., and the entire glass piece was immersed in the acetate buffer solution at 100 ° C. for a predetermined time. During the immersion of the glass piece, the temperature of the acetate buffer (immersion temperature) was maintained at 100 ° C. After a predetermined soaking time, a glass piece was taken out from the acetate buffer, rinsed with ion-exchanged water, and further placed on a paper towel to remove moisture adhering to the glass piece and dried. The amount of charge as “charging behavior” of the surface of the glass piece thus dried was evaluated using an EUPS device. Two types of immersion time of 5 minutes and 1 hour were prepared as the glass piece immersion time, and the amount of charge on the surface of the glass piece under each condition was evaluated. Separately, a glass piece that was not immersed in an acetate buffer solution (corresponding to the non-immersed control glass piece) was prepared, and the amount of charge on the surface was evaluated using an EUPS device. The evaluation results are shown in Table 1 below.

  As apparent from the comparison between the control glass piece and the glass piece to be evaluated (samples No. 1 and 2) in Table 1, the charge amount was 25% by immersing the glass piece in an acetic acid buffer solution at 100 ° C. It became smaller. From this result, it can be seen that the charge amount on the surface of the glass piece can be an index for inspecting the immersion history of the glass piece, that is, whether it has been present in the liquid in the past.

Claims (6)

  A method for estimating the immersion history of a glass piece, comprising the steps of evaluating the charging behavior of the surface of the glass piece immersed in the liquid and estimating the immersion history of the glass piece based on the evaluation result.   The charge behavior is at least one selected from the group consisting of charge magnitude, excitation power dependence, discharge time constant, temperature dependence of charge magnitude, and temperature dependence of discharge time constant. The immersion history estimation method of the glass piece of description.   The glass piece immersion history estimation method according to claim 1 or 2, wherein the evaluation of the charging behavior is performed using a photoelectron spectrometer.   Separately from the glass piece to be evaluated, a control glass piece having the same composition as the glass piece to be evaluated is prepared, and the control glass piece is immersed in a liquid having the same composition as the liquid in which the glass piece to be evaluated was immersed. The control glass piece immersed in the liquid and the glass piece to be evaluated are evaluated for the behavior of the charging, and the evaluation results are compared with each other. Of immersion history estimation of glass pieces.   Separately from the glass piece to be evaluated, a control glass piece having the same composition as that of the glass piece to be evaluated and never existing in the liquid is prepared, and the charging behavior for each of the control glass piece and the glass piece to be evaluated is prepared. The glass piece immersion history estimation method according to claim 1, further comprising a step of evaluating a charge amount of the glass surface and comparing the charge amounts with each other.   A foreign matter mixing history for estimating a mixing history of the glass piece into the food by applying the estimation method according to any one of claims 1 to 5 for the glass piece mixed as a foreign matter in the food. Estimation method.

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