JP2014016373A - Method of measuring component amount in coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of precisely measuring a component amount in a coating film continuously.SOLUTION: A method of measuring a component amount in a coating film continuously measures the component amount of each solvent while drying the coating film containing a plurality of solvents. A plurality of light sources irradiate the coating film and a plurality of light-receiving sensors receive light having different wavelengths, respectively. The method includes the steps of: continuously measuring the light absorption amount of different wavelengths absorbed by the coating film; and calculating the component amount in the coating film from the measured light absorption amount.

Description

  The present invention relates to a method for measuring the amount of a component in a coating film.

  Conventionally, as a method for simultaneously measuring the amount of a component in a certain object, a method has been proposed in which the amount of absorption of light is different for each amount of component and light is irradiated to examine the degree of absorption.

  As one of the methods, there is a method of converting a component amount by selecting light of a specific wavelength and measuring absorbance at the wavelength light. For example, in Patent Document 1, an electrophotographic photosensitive material having a plurality of functional layers is irradiated with a plurality of lights having wavelengths that are most easily absorbed by each functional layer, and the film thickness is obtained from the amount of absorption.

  Moreover, in patent document 2, infrared light is irradiated to the aqueous solution containing a multicomponent, the infrared light spectrum in 1500 nm-1850 nm is calculated | required, and the main component is obtained from the infrared absorption spectrum in case the component quantity calculated | required previously is known. A method has been proposed in which the amount of each component is determined by specifying an absorption wavelength and measuring the amount of absorption at that wavelength.

  As another method, as shown in Non-patent Document 1, when the total amount is the same, the internal component amount ratio is changed to obtain a calibration curve that is dependent on the component amount ratio of the absorbance. There is a method of determining the amount of a component in an object by measuring the change in absorbance by irradiating. This method is also proposed in Patent Document 3.

  In addition, as a method for simultaneously measuring a plurality of component amounts in a certain object, Patent Document 4 irradiates a coating film in which a plurality of types of components are mixed with the same number of types of wavelength light as each component amount, and each wavelength Measure the absorbance of all components of light, and obtain the proportional coefficient of each component amount with respect to the absorbance at each wavelength from the relationship between the absorbance at each wavelength and the amount of each component in advance. A method has been proposed in which a determinant is set and a component amount of each component is calculated by solving the determinant.

  However, all of the methods proposed in Patent Documents 1 to 4 described above are based on the premise that the amount of solvent in the measurement target does not change. Therefore, when the object is a coating film being dried and the amount of solvent in the film is measured, in the methods of Patent Documents 1 to 4, the solvent in the coating film evaporates into a gas, and only the solvent in the film is obtained. In addition, since the evaporated gas absorbs infrared light, it is difficult to correctly measure the amount of components in the coating film.

  In order to avoid the gas other than the measurement object from affecting the measurement, a method of performing measurement while removing the gas has been proposed. For example, in Patent Document 5, infrared absorbance is measured after removing a gas that interferes with the measurement using a column. Moreover, in patent document 6, gas is removed using a removal agent and the amount of components is measured.

JP-A-9-329899 JP-A-8-29332 JP 7-294519 A JP 7-239300 A JP 2002-139431 A JP 2003-014716 A

"DRYING PROCESS MONITORING BY RAPID SCANNING FT-IR SPECTROMETER", INDUSTRIAL COATING RESEARCH 5 (2004) p107-123

  However, in the method using the column and the removal agent proposed in Patent Literature 5 and Patent Literature 6, if the column or the removal agent absorbs the gas to some extent, the force to absorb the gas becomes dull and the function is deteriorated. Become. Therefore, in the method of measuring the amount of components after removing the gas with a column or remover, the amount of components in the coating film continuously while removing the gas evaporating from the coating film, such as in industrial applications. It was very time consuming to measure.

  The present invention has been made in view of such circumstances, and it is possible to accurately measure the amount of components in a coating film continuously while removing gas evaporated from the coating film. The purpose is to provide a measurement method.

  In order to achieve the above object, the method for measuring the amount of a component in a coating film of the present invention is a method for continuously measuring the component amount of each solvent during the drying of a coating film containing a plurality of solvents, The film is irradiated with light from a plurality of light sources, and a plurality of light receiving sensors respectively receive light having different wavelengths, and the step of continuously measuring the light absorption amount of different wavelengths absorbed by the coating film is measured. And calculating a component amount in the coating film from the light absorption amount.

  According to the present invention, the coating film is irradiated by irradiating the coating film with light while removing the vaporized gas from the coating film, measuring the light absorption amount, and calculating the component amount inside the coating film from the light absorption amount. The gas evaporated from the liquid can be prevented from staying and absorbing the irradiated light. Thereby, since the component amount of the evaporated gas is not measured, the component amount in the coating film can be accurately measured. In addition, since no column or remover is used, continuous component amounts can be measured.

  The number of solvents to be measured and the number of light receiving sensors are preferably the same.

The step of measuring the amount of light absorption by irradiating the coating film with light is performed by irradiating the coating film in which n types of components C1... Cn are mixed with the same number of types of wavelength light L1. And measuring the light absorption amount A1... An based on all components of each wavelength light, and calculating the component amount in the coating film from the light absorption amount in each wavelength light L1. From the proportionality coefficient k ₁₁ ... k _nn obtained in advance from the relationship between the light absorption amount of each of the n types of components C 1... Cn and the amount of each component, and the measured light absorption amounts A 1. preferably includes a step of calculating component amounts a ₁ · · · a _n unknown components in the coating film by solving the represented determinant 1).

  Furthermore, the following invention is disclosed.

  The method of removing the gas evaporated from the coating film is preferably a method of removing the gas by air movement in the vicinity of the coating film. Removal by air movement is preferable because it is a simple method.

  The air movement in the vicinity of the coating film is preferably air movement by applying air to the vicinity of the coating film and / or sucking the vicinity of the coating film. A blower (or suction) device used for removal by air movement is preferable because it requires relatively little maintenance work.

  The functional film manufacturing method measures the amount of components in a coating film at regular intervals by a step of applying a coating solution to a traveling support to form a coating film and a method for measuring the amount of components in the coating film. And a step of adjusting the drying conditions of the coating film so that the variation in the component amount is within a predetermined range.

  Since the drying conditions are adjusted so that the variation in the measured component amount in the coating film falls within a predetermined range, a functional film with stable quality can be produced.

  The step of adjusting the drying condition of the coating film is a step of adjusting the drying condition so that the variation in the component amount is within ± 2% from the average value converted from the component amount measured immediately before 1 second or more. Is preferred.

  The reason for setting it to the latest 1 second or more is that the film thickness value measured within the last 1 second may have already been affected by the film thickness unevenness. If the film thickness value measured within the last 1 second is converted into the average value, it will be found that even if the average value is compared with the measured film thickness value, film thickness unevenness occurs. This is because it may not be possible.

  The reason why it is within ± 2% is that when the film thickness error is 2% or more, the function as a functional film does not appear.

  ADVANTAGE OF THE INVENTION According to this invention, the component quantity in a coating film can be measured correctly continuously, removing the gas evaporated from the coating film.

Schematic configuration diagram of measuring device Graph showing an example of light absorption spectrum Graph showing an example of a calibration curve for wavelength λ1 Graph showing an example of a calibration curve for wavelength λ2 Explanatory drawing which shows one aspect of the method of manufacturing a functional film Table showing the results of the examples

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. The present invention will be described with reference to the following preferred embodiments, but can be modified in many ways without departing from the scope of the present invention, and other embodiments than the present embodiment can be used. be able to. Accordingly, all modifications within the scope of the present invention are included in the claims.

  FIG. 1 is a schematic configuration diagram of a measuring apparatus used for measuring the amount of components in a coating film. The measuring device 10 includes a first light source 12 and a second light source 14, a first sensor 16 that receives light from the first light source 12, and a second sensor 18 that receives light from the second light source 14. A blower fan 24 for supplying air to the vicinity of the coating film 22 formed on the support 20 and a suction device 26 for sucking air from the blower fan 24 are provided. The measuring apparatus 10 further includes a calculator 28 that is electrically connected to the first sensor 16 and the second sensor 18.

The 1st light source 12 and the 2nd light source 14 are comprised so that the light of a different wavelength can be irradiated to a coating film. The configuration of the measurement apparatus 10 illustrated in FIG. 1 is not limited, and light from a single light source may be applied to the coating film 22 with light having different wavelengths by transmitting the light through a plurality of filters. Light emitted from the first light source 12 and the second light source 14 ^is preferably light of a wavelength of 1400nm ^-1 ~7000nm -1. To select light having a wavelength of 1400nm ^-1 ~7000nm ^-1 is because in the range of the absorption band wavelength of functional machine having an organic solvent.

  Light is irradiated from the first light source 12 and the second light source 14 toward the coating film 22. Light from the first light source 12 and the second light source 14 passes through the coating film 22 and the support 20 and is received by the first sensor 16 and the second sensor 18. When passing through the coating film 22 and the support 20, light having a predetermined wavelength is absorbed according to the components contained in the coating film 22. The calculator 28 receives the measurement data of the light absorption amount from the first sensor 16 and the second sensor 18 and calculates the component amount of the coating film 22 based on the measurement data.

  The measuring apparatus 10 shown in FIG. 1 includes both a blower fan 24 and a suction device 26. Thereby, the gas evaporated from the coating film 22 is removed. However, the present invention is not limited to this, and only one of the blower fan 24 and the suction device 26 may be provided.

  According to the present invention, the evaporated gas from the coating film 22 that may affect the measurement of the component amount is removed. Therefore, the component amount of the gas is not included in the light absorption amount, and is accurately contained in the coating film. The amount of ingredients can be measured.

  Next, the measuring method of the component amount in the coating film will be described in more detail. The case where the components contained in the coating film are two solvents A and B and the amounts of the components are measured will be described as an example.

  First, the spectrum of the relationship between the light absorption amounts of the solvents A and B and the irradiation wavelength is measured. As shown in FIGS. 2A and 2B, the measured values are plotted with the wavelength on the horizontal axis and the infrared absorption amount on the vertical axis. From both measured spectra, the same number of wavelengths as the measured component amount (in this case, two) are selected.

  There are two criteria for selecting the two wavelengths: (1) at least one wavelength has a different amount of light absorption between the solvents, and (2) a wavelength having the highest possible absorption amount. Based on this criterion, as shown in FIGS. 2A and 2B, the wavelength corresponding to the portion surrounded by a circle is selected. Here, of the two selected wavelengths, the lower wavelength is λ1 (nm) and the higher wavelength is λ2 (nm).

  Next, for each of the solvent A and the solvent B, a calibration curve is created by obtaining the relationship between the solvent amount and the absorption amount at the wavelength λ1 (nm) and the wavelength λ2 (nm). The calibration curve is a correlation between the light absorption amount (peak intensity) and the component amount (mass%) of the measurement object. This calibration curve is created based on light absorption amount spectrum data obtained by measuring a measurement object with a known component amount. FIGS. 3A and 3B are examples of graphs showing the relationship between the component amount and the infrared absorption amount when the solvent A and the solvent B are irradiated with the wavelength λ1 (nm). 4A and 4B are examples of graphs showing the relationship between the component amount and the infrared absorption amount when the solvent A and the solvent B are irradiated with the wavelength λ2 (nm). From the respective calibration curves shown in FIGS. 3 and 4, proportional coefficients a, b, c, and d of the solvent amount and the absorption amount are obtained.

  Finally, the measurement of the component amount will be described. The unknown component amount of the solvent A contained in the coating film is X, and the unknown component amount of the solvent B is Y. The coating film is irradiated with light having a wavelength λ1 (nm) and a wavelength λ2 (nm), and the amount of absorption is measured. If the measured absorption amount (absorbance) of λ1 (nm) is Abs1, the absorption amount (absorbance) of λ2 (nm) is Abs2, and the proportionality coefficient obtained from the calibration curve is a, b, c, d, the following equation Holds.

(1) aX + bY = Abs1, (2) cX + dY = Abs2
X and Y are obtained by solving the two simultaneous equations (1) and (2). Therefore, the amounts of solvents A and B are calculated respectively. When the two formulas (1) and (2) are expressed by determinants, the following formulas are obtained.

  Next, the example of the manufacturing method of the functional film of this invention is demonstrated with reference to FIG. Note that. The same components as those of the measuring apparatus already described may be denoted by the same reference numerals and description thereof may be omitted.

  As shown in FIG. 5, the web W is delivered from the film roll 62 using the delivery device 60. A coating device 64 is disposed downstream of the delivery device 60. A coating film (not shown) is formed on the web W by supplying the coating liquid from the coating device 64 to the web W while the web W is supported by the backup roller 66. Not only one type of coating liquid is supplied, but also a plurality of types of coating liquids can be supplied. Note that the coating device 64 is not limited to the extrusion type shown in FIG. 5, and as long as the coating liquid can be supplied to the web, a roll coater type, a gravure coat type, a roll coat plus doctor type, a reverse roll coater type, a slide A coat mold or the like can be used.

  A drying zone 68 is provided downstream of the coating device 64. A drying air device 70 is provided in the drying zone 68. The coating film on the web W can be dried by the drying air from the drying air device 70. In the drying zone 68, the first light source 12, the second light source 14, the first sensor 16 that receives light from the first light source 12, and the second sensor 18 that receives light from the second light source 14. Is placed. Further, the blower fan 24 is installed in the drying zone 68. Air from the blower fan 24 is supplied from a direction perpendicular to the running direction of the web W in the vicinity of the coating film irradiated with infrared light from the first light source 12 and the second light source 14. Thereby, the gas evaporated from the coating film is removed.

  The first sensor 16 and the second sensor 18 are electrically connected to the data processing device 72. Similarly, the drying air device 70 is electrically connected to the data processing device 72. Measurement data (absorbance) is sent from the first sensor 16 and the second sensor 18 to the data processing device 72. The data processing device 72 calculates the component amount in the coating film from the proportionality coefficient obtained beforehand from the calibration curve and the measurement data. The calculation of the component amount is performed on the traveling web W at regular intervals, for example, at intervals of 0.1 seconds. The calculated component amount is displayed on the display of the data processing device 72, for example. Further, the calculated component amount is recorded in the data processing device 72 every time. An average value can be calculated from the recorded component amounts.

  The average value of the component amounts is compared with the calculated component amount, and the variation in the component amounts is calculated. The data processing device 72 controls the air flow direction, temperature, and the like of the dry air device 70 so that the variation in the component amount is within a predetermined range. By controlling the drying air device 70, the variation in the component amount is controlled within a predetermined range. Thereby, the functional film stable in quality can be manufactured.

  Regarding the variation in the component amount, the average value converted from the component amount measured immediately before the component amount measurement is compared with the measured component amount, and it is determined whether the variation is within ± 2%. When the variation is ± 2% or more, the data processing device 72 adjusts the drying condition of the drying air device 70 so that it is within ± 2%.

  The reason why the average value converted from the component amount measured immediately before one second or more and the measured component amount are compared is as follows.

  The film thickness value measured within the last 1 second may have already been affected by the film thickness unevenness. For this reason, if the average value is converted into the average value, it may not be possible to find out that film thickness unevenness has occurred even if the average value is compared with the measured film thickness value.

  The web W fed out from the drying zone 68 is guided by guide rollers 74 and 76 and wound by a winder 78 provided downstream of the guide rollers 74 and 76.

  As the web to which the present invention is applied, a film of triacetylcellulose (TAC), polyethylene terephthalate (PET), or polyethylene naphrelate (PEN) can be preferably used.

  Moreover, the organic solvent containing the material suitable for a magnetic tape and an optical compensation film can be used suitably as a coating liquid apply | coated to the above-mentioned web.

  The present invention will be described more specifically with reference to the following examples. The materials, production conditions, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the following specific examples.

<Example 1>
A MEK (methyl ethyl ketone) / cyclohexanone mixed solution having a molar ratio of 1: 1 is prepared, and the mixed solution is used on a 80 μm thick triacetyl cellulose (Fujitack, manufactured by Fuji Film Co., Ltd.) using a bar (diameter 3 mm). Was applied. Subsequently, the coating film was dried. Next, while applying a wind of 0.2 m / s to the coating film, irradiation with two wavelengths of wavelengths of 3600 nm and 2300 nm was performed, and the light absorption amount was continuously measured. Proportional coefficients of the MEK amount and the cyclohexanone amount with respect to the light absorption amount of each wavelength light were previously determined. Here, the proportion coefficient of the MEK amount with respect to the light absorption amount of 3600 nm is k ₁₁ , the proportion coefficient of the cyclohexanone amount with respect to the light absorption amount of 3600 nm is k ₁₂ , the proportion coefficient of the MEK amount with respect to the light absorption amount of 2300 nm is k ₂₁ , and the amount of cyclohexanone. the proportionality coefficient for the light absorption amount of 2300nm of the _{k 22.} The following determinant is solved with the unknown component amount of MEK as a ₁ , the unknown component amount of cyclohexanone as a ₂ , the light absorption amount of light with a wavelength of 3600 nm as A ₁ , and the light absorption amount of light as a wavelength of 2300 nm as A _2. Thus, the time dependency of each component amount of MEK and cyclohexanone was calculated.

  As described above, whether or not there is fluctuation in the upper and lower sides of the calculated component amount time dependency was evaluated on the result of measuring the component amount. Here, the wobbling is defined as a wobbling that a deviation of 10 times or more of the average deviation width of the actual data occurs from the linear approximation expression up to the sixth order obtained for the measurement data. When the time dependency of the component amount was calculated, the case where the component amount did not fluctuate was evaluated as ◯, and when the component amount was calculated as the time dependency, the case where the component amount was unstable was evaluated as x.

<Example 2>
In Example 1, the coating solution was an acetone / cyclohexane mixed solution having a molar ratio of 1: 1, and the time dependency of the amount of components was similarly changed except that the wavelengths irradiated when measuring the absorbance were 6700 nm and 5900 nm. It was measured.

<Example 3>
In Example 1, the coating solution was a MEK / cyclohexanone / cyclohexane mixed solution having a molar ratio of 1: 1: 1. When measuring the absorbance of this mixed solution, the wavelengths irradiated were 5900 nm, 3600 nm, and 2300 nm. Here, the proportionality coefficient k ₁₁ of the MEK amount to 5900 Nm wavelength light, the proportionality factor k _{12 of} the cyclohexanone amount to 5900 nm wavelength light, the proportionality factor k _{13 of} the cyclohexane amount to wavelength light of 5900 nm, the MEK amount of 3600 nm wavelength light Proportional coefficient k ₂₁ , Proportional coefficient k ₂₂ of cyclohexanone amount to 3600 nm wavelength light, Proportional coefficient k _{23 of} cyclohexane amount to 3600 nm wavelength light, Proportion factor k _{31 of} MEK amount to 2300 nm wavelength light, Cyclohexanone amount The proportional coefficient k ₃₂ to 2300 nm wavelength light and the proportional coefficient k _{33 of} cyclohexane amount to 2300 nm wavelength light were used. The unknown component amount of MEK is a ₁ , the unknown component amount of cyclohexanone is a ₂ , the unknown component amount of cyclohexane is a ₃ , the light absorption amount of light with a wavelength of 5900 nm is A ₁ , and the light absorption amount of light with a wavelength of 3600 nm And A ₂ , the light absorption amount of light having a wavelength of 2300 nm was A _3, and the component amounts of MEK, cyclohexanone, and cyclohexane were calculated by solving the following determinant.

<Comparative Example 1>
In Example 1, the time dependency of the component amount was measured in the same manner except that no wind was applied to the coating film.

<Comparative Example 2>
In Example 2, the time dependency of the component amount was measured in the same manner except that no wind was applied to the coating film.

<Comparative Example 3>
In Example 3, the time dependency of the component amount was measured in the same manner except that no air was applied to the coating film.

  The table | surface of FIG. 6 displays the result of the fluctuation | variation to the presence or absence of the ventilation to a coating film, and the amount of components about Examples 1-3 and Comparative Examples 1-3. As is clear from the table, in Examples 1 to 3 in which air was supplied to the coating film, the evaluations were all good. On the other hand, about Comparative Examples 1-3, all evaluation was x.

DESCRIPTION OF SYMBOLS 10 ... Measuring apparatus, 12 ... First light source, 14 ... Second light source, 16 ... First sensor, 18 ... Second sensor, 24 ... Blower fan, 26 ... Suction machine, 28 ... Calculator

Claims (3)

A method for continuously measuring the amount of each solvent component during drying of a coating film containing a plurality of solvents,
The step of irradiating the coating film with light from a plurality of light sources, wherein the plurality of light receiving sensors respectively receive light having different wavelengths, and continuously measuring the light absorption amount of the different wavelengths absorbed by the coating film; ,
Calculating a component amount in the coating film from the measured light absorption amount;
A method for measuring the amount of a component in a coating film containing.   The method for measuring the amount of a component in a coating film according to claim 1, wherein the number of the solvent to be measured and the plurality of light receiving sensors are the same. The step of irradiating the coating film with light to measure the amount of light absorption includes applying the same number of types of wavelength light L1... Ln to the coating film in which n types of components C1. Irradiating and measuring a light absorption amount A1... An by all components of each wavelength light,
The step of calculating the component amount in the coating film from the light absorption amount was obtained in advance from the relationship between the light absorption amount of each of the n types of components C1... Cn and the component amounts in each wavelength light L1. From the proportionality coefficient k11... Knn and the measured light absorption amount A1... An, the amount of components a1. The method for measuring the amount of components in the coating film according to claim 1 or 2, comprising a step of calculating an.