CA2279904C - Method for measuring the components of a coating on a moving base material - Google Patents
Method for measuring the components of a coating on a moving base material Download PDFInfo
- Publication number
- CA2279904C CA2279904C CA002279904A CA2279904A CA2279904C CA 2279904 C CA2279904 C CA 2279904C CA 002279904 A CA002279904 A CA 002279904A CA 2279904 A CA2279904 A CA 2279904A CA 2279904 C CA2279904 C CA 2279904C
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- Prior art keywords
- coating
- measurement
- measuring
- paper
- amount
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Links
- 238000000576 coating method Methods 0.000 title claims abstract description 63
- 239000011248 coating agent Substances 0.000 title claims abstract description 61
- 238000000034 method Methods 0.000 title claims abstract description 36
- 239000000463 material Substances 0.000 title claims description 12
- 238000005259 measurement Methods 0.000 claims abstract description 70
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims abstract description 42
- 229910000019 calcium carbonate Inorganic materials 0.000 claims abstract description 21
- 239000005995 Aluminium silicate Substances 0.000 claims description 24
- 235000012211 aluminium silicate Nutrition 0.000 claims description 24
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 claims description 24
- 238000010521 absorption reaction Methods 0.000 claims description 16
- 238000009792 diffusion process Methods 0.000 claims description 6
- 239000011111 cardboard Substances 0.000 claims description 4
- 238000001228 spectrum Methods 0.000 claims description 3
- 239000011087 paperboard Substances 0.000 claims description 2
- 239000000123 paper Substances 0.000 description 42
- 229960000829 kaolin Drugs 0.000 description 21
- 239000002585 base Substances 0.000 description 16
- 229960003563 calcium carbonate Drugs 0.000 description 16
- 235000010216 calcium carbonate Nutrition 0.000 description 16
- 230000009102 absorption Effects 0.000 description 14
- 230000006870 function Effects 0.000 description 9
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 8
- 239000002023 wood Substances 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000002310 reflectometry Methods 0.000 description 3
- 239000000945 filler Substances 0.000 description 2
- -1 for example Substances 0.000 description 2
- 239000012458 free base Substances 0.000 description 2
- 238000005286 illumination Methods 0.000 description 2
- 238000011545 laboratory measurement Methods 0.000 description 2
- 238000011005 laboratory method Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 1
- 241000258240 Mantis religiosa Species 0.000 description 1
- 239000002174 Styrene-butadiene Substances 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- MTAZNLWOLGHBHU-UHFFFAOYSA-N butadiene-styrene rubber Chemical compound C=CC=C.C=CC1=CC=CC=C1 MTAZNLWOLGHBHU-UHFFFAOYSA-N 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 239000011115 styrene butadiene Substances 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3563—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing solids; Preparation of samples therefor
Abstract
The invention relates to a method for measuring paper coating components by infrared measurement whereby the paper components are determined by reflection measurement of a middle infrared range in such a manner that the amount of calcium carbonate in the coating is determined in the wavelength range 2.5-8 µm.
Description
METHOD FOR MEASURING THE COMPONENTS OF A COATING ON A MOVING
BASE MATERIAL
The invention relates to a rnethod for measuring components of a coating on a moving base material by infrared measurement.
The measurement of the amount of coating on coated paper is one of the most important paper quality measurements; in this description paper means conventional paper and/or cardboard.
The amount of coating has conventionally been measured (US No.
5 338 361) continuously by absorption measurement of a near infrared range (NIR). In absorption measurement of an IR range the intensity of an IR beam absorbed by the coating or a quantity proportional thereto is determined as a function of the wavelength of the beam; the intensity of the beam absorbed by the IR beam measured by a wavelength corresponding to an absorption peak of the component to be measured correlates with the amount of coating.
Measuring paper coating components by infrared measurement is known in the art and will not be described here in greater detail.
The coating component to be measured is usually kaolin having ab-sorption peaks in the NIR range. However, NIR measurement cannot be used for measuring the other important coating component, calcium carbonate, since calcium carbonate has no absorption peak in the NIR range. The total amount of coating can then be calculated on the basis of kaolin measurement assuming that the ratio between the amounts of kaolin and calcium carbonate in the coating is constant. In reality, however, the ratio between the amounts of kaolin and calcium carbonate is not always constant, but may vary. Thus, the prior art method described above does not provide accurate results par-ticularly in measuring the amount of calcium carbonate. In addition, the method can only be employed when kaolin is used; when kaolin is not used as a coating component said method cannot be employed at all.
US patent (No.) 5 455 422 describes a method in which the amount of coating is measured by measuring, for example, the absorption peak of la-tex at the wavelength 2.30 micrometers and the absorption peak of clay at the wavelength 2.21 micrometers. Said patent further describes the measurement of calcium carbonate by measuring the amount of backscattering at the wave-length 2.09 micrometers. However, for measuring the amount of calcium car-bonate said method is unreliable an inaccurate. The amount of calcium car-bonate could also be determined, for example, on the basis of kaolin measurement assuming that the ratio between the amounts of kaolin and calcium carbonate in the coating is constant. However, this is not always the case and problems are created particularly if the kaolin content is low i.e.
below approximately 20 % and the carbonate content correspondingly high i.e.
approximately 80 %.
EP publication (No.) 0 332 018 shows a method in which the amount of kaolin in paper is measured by transmission measurement, for example, at approximately the wavelengths 1.4 and 2.2 micrometers. However, it is very difficult to determine by transmission measurement what the portion of the coating in the measurement result is. Furthermore, the portion of calcium carbonate has to be approximated in a manner described in the previous chapter.
GB publication (No.) 2 127 541 shows how the amount of additives in paper is measured by transmission measurement. The publication describes the measurement of the amount of calcium carbonate by measuring the absorption peaks at the wavelengths 11.54 micrometers and 11.77 micrometers. The amount of coating cannot be measured by said method since the fillers in base paper are included in the results. Furthermore, the absorption of paper can be so high that measurement through paper is not possible. Moreover, in its entirety the accuracy of the measurement results is not good enough.
The present invention is directed towards elimination of the drawbacks described above.
In a particular aspect, the present invention is directed towards the introduction of a new method for measuring the components of a coating on a moving base material by infrared measurement in such a manner that the measurement is better applicable than previous measurements particularly for determining various coating components and that the fillers on the base material do not cause problems in the measurement. In a further aspect, the invention is directed towards the introducing of a method for measuring coating components on a moving base material, for example, paper coating components in such a way that the measurement is not disturbed by a high absorption of the base material, for example, paper.
2a The method of the invention is characterized in that the components of a coating are determined by reflection measurement in the wavelength range 2.5-12 pm in such a manner that the amount of calcium carbonate in the coating is determined in the wavelength range 2.5-8 pm.
BASE MATERIAL
The invention relates to a rnethod for measuring components of a coating on a moving base material by infrared measurement.
The measurement of the amount of coating on coated paper is one of the most important paper quality measurements; in this description paper means conventional paper and/or cardboard.
The amount of coating has conventionally been measured (US No.
5 338 361) continuously by absorption measurement of a near infrared range (NIR). In absorption measurement of an IR range the intensity of an IR beam absorbed by the coating or a quantity proportional thereto is determined as a function of the wavelength of the beam; the intensity of the beam absorbed by the IR beam measured by a wavelength corresponding to an absorption peak of the component to be measured correlates with the amount of coating.
Measuring paper coating components by infrared measurement is known in the art and will not be described here in greater detail.
The coating component to be measured is usually kaolin having ab-sorption peaks in the NIR range. However, NIR measurement cannot be used for measuring the other important coating component, calcium carbonate, since calcium carbonate has no absorption peak in the NIR range. The total amount of coating can then be calculated on the basis of kaolin measurement assuming that the ratio between the amounts of kaolin and calcium carbonate in the coating is constant. In reality, however, the ratio between the amounts of kaolin and calcium carbonate is not always constant, but may vary. Thus, the prior art method described above does not provide accurate results par-ticularly in measuring the amount of calcium carbonate. In addition, the method can only be employed when kaolin is used; when kaolin is not used as a coating component said method cannot be employed at all.
US patent (No.) 5 455 422 describes a method in which the amount of coating is measured by measuring, for example, the absorption peak of la-tex at the wavelength 2.30 micrometers and the absorption peak of clay at the wavelength 2.21 micrometers. Said patent further describes the measurement of calcium carbonate by measuring the amount of backscattering at the wave-length 2.09 micrometers. However, for measuring the amount of calcium car-bonate said method is unreliable an inaccurate. The amount of calcium car-bonate could also be determined, for example, on the basis of kaolin measurement assuming that the ratio between the amounts of kaolin and calcium carbonate in the coating is constant. However, this is not always the case and problems are created particularly if the kaolin content is low i.e.
below approximately 20 % and the carbonate content correspondingly high i.e.
approximately 80 %.
EP publication (No.) 0 332 018 shows a method in which the amount of kaolin in paper is measured by transmission measurement, for example, at approximately the wavelengths 1.4 and 2.2 micrometers. However, it is very difficult to determine by transmission measurement what the portion of the coating in the measurement result is. Furthermore, the portion of calcium carbonate has to be approximated in a manner described in the previous chapter.
GB publication (No.) 2 127 541 shows how the amount of additives in paper is measured by transmission measurement. The publication describes the measurement of the amount of calcium carbonate by measuring the absorption peaks at the wavelengths 11.54 micrometers and 11.77 micrometers. The amount of coating cannot be measured by said method since the fillers in base paper are included in the results. Furthermore, the absorption of paper can be so high that measurement through paper is not possible. Moreover, in its entirety the accuracy of the measurement results is not good enough.
The present invention is directed towards elimination of the drawbacks described above.
In a particular aspect, the present invention is directed towards the introduction of a new method for measuring the components of a coating on a moving base material by infrared measurement in such a manner that the measurement is better applicable than previous measurements particularly for determining various coating components and that the fillers on the base material do not cause problems in the measurement. In a further aspect, the invention is directed towards the introducing of a method for measuring coating components on a moving base material, for example, paper coating components in such a way that the measurement is not disturbed by a high absorption of the base material, for example, paper.
2a The method of the invention is characterized in that the components of a coating are determined by reflection measurement in the wavelength range 2.5-12 pm in such a manner that the amount of calcium carbonate in the coating is determined in the wavelength range 2.5-8 pm.
The basic idea of the invention is that the coating components are determined by reflection measurement of a middle infrared range. It is also es-sential that the amount of calcium carbonate in the coating is determined in the wavelength range 2.5-8 m.
The method of the invention provides an accurate and useful method for determining paper coating components using reflection measure-ment of the middle infrared range 2.5-12 m. The method is particularly appli-cable to be used for measuring paper coating components i.e. for example measuring kaolin at the wavelength 2.5-11 m, preferably at 8-11 m and/or measuring calcium carbonate at the wavelength 2.5-8 m, preferably at 3.0-7.3 pm. The measurement can generally be carried out at any wavelength in the middle infrared range, for example, at 2.5-12 m.
The method of the invention is applicable for measuring the coating components on a moving base material also from the surface of a roller of a paper coating machine, a roller of a paper machine and/or generally from the surface of a metal plate.
Reflection measurement i.e. measurement where a reflection source and a receiver are on the same side of the object to be measured, can -be carried out using specular reflection measurement whereby the measuring beam is directed onto the surface of the base material as an oblique beam of parallel rays and a parallel reflected beam reflecting from the surface of the base material is detected by a detector i.e. the intensity of the reflected beam is determined as a function of the wavelength.
The invention can be particularly advantageously implemented as diffusion reflection, in which case the measuring beam is directed towards the object to be measured and the intensity of the radiation diffusely reflecting from the object in all directions is determined as a function of the wavelength;
the illumination of the object can also be diffusely implemented.
Reflection measurement of the MIR range provides a very good cor-relation for the amount of coating components, particularly kaolin and carbon-ate and mixtures of these. The correlation is also very good for various base papers and/or cardboards in calibrating the measurement of their coatings.
The MIR range has many advantages compared with the NIR range. In the MIR range high absorptions are achieved for all essential coating components, in addition the peaks are sharp and the scattering is insignificant. The sharp peaks are a desirable property as for the function of detectors of measuring apparatuses based on interference filters, and the small quantity of scattering allows the structural variation of the coating without the calibration suffering.
The fact that the paper industry is willing to start using carbonate-based coat-ings, which cannot be directly measured in the NIR range, increases the sig-nificance of the result.
The use of the method of the invention enables the implementation of measuring apparatuses, which can be used for on-line measurement of pa-per and/or cardboard coating components by paper and coating machines, for on-line measurement of coatings on rollers of paper coating machines or pa-per machines or generally on metal plates and as paper and coating research tools in laboratories. Particularly the use of the method of the invention en-ables the implementation of a small-scale measuring apparatus of the coating amount variation for laboratory use by designing the optics of the apparatus to suit small-scale measurement. In small-scale measurement the size of the measuring area can be 0.1-100 mmz, preferably 0.1-10 mmz, more preferably 0.1-2 mm2, and even smaller than this. Naturally the measuring area can also be larger, for example, of the size about 1 cm2 (n = 1-10 or larger) as is known from prior art. The total amount of the coating to be measured or in small-scale measurement the coating amount to be measured may vary, for example, between 3-40 glm2, preferably 17-25 g/m2.
In the following the invention will be described in greater detail by means of the preferred embodiments with reference to the accompanying drawings, in which Figure 1 is a diagram showing diffusion reflection measurement, Figure 2 is a diagram showing specular reflection measurement, Figures 3 and 4 show reflectivity (%) i.e. the intensity of light meas-ured as a function of a wavelength at the wavelength about 2-11 m, Figures 5 - 9 show coating amounts determined according to the method of the invention as a function of coating amounts determined by labo-ratory measurements and Figure 10 shows small-scale variation of coating amount measured by the method of the invention, the measuring field being 1 mm2.
In Figure 1 a parallel measuring beam B, is directed using a lens 1 obliquely to a paper 2 to be measured, from which a parallel reflected beam B2 is directed using a lens system 3 to a detector 4. The measuring beam B, may consist of light rays having various wavelengths, for example, 2-12 m. The _, ...~..
_._.. ~.,.__.._~_...,.. ._ detector 4 determines the intensity of the beam B2 as a function of a different beam wavelength L The paper 2 may be stationary, for example, in laboratory measurement, or it may be in motion, for example in a paper machine. When the paper 2 moving in the paper machine is being measured the measuring 5 apparatuses are preferably located in a measuring frame traversing in a cross direction in relation to the direction of the paper 2 in which case the measure-ment can be performed at the width of the entire paper 2. The illumination of the paper by the measuring beam B, and the detection of the reflected beam BZ as a function of the wavelength X of the light are known in the art, and will therefore not be described in more detail here. In measuring the MIR range specular optics can preferably be used, the specular optics being known per se and therefore not described in more detail here.
Figure 2 is a diagram showing specular reflection measurement. An incoming beam B, is directed, for example, as a beam of parallel rays at an oblique angle towards the paper 2 and the beam B, of parallel rays reflected from the paper is detected in a manner known in the art using the lens system 3 and the detector 4, the intensity of the reflected beam is detected as a func-tion of the wavelength k of the light.
Figures 3 and 4 graphically show the results of specular reflection measurement performed as shown in Figure 2 compared with the reflectivity of the base paper, a reflection spectrum of kaolin coated paper in Figure 1 and carbonate coated paper in Figure 2 being shown in relation to the spectrum of the base paper. The kaolin peak is shown in Figure 1 at the wavelength 8.5 -10 m and the carbonate peak in Figure 2 at the wavelength 6.5 - 7 m. The peak of styrene butadiene used as a binder is seen around 3 m (Figure 4).
The peaks are very pronounced since the reflectivity of coated paper at the wavelengths of the peaks of the pigments is 5-11 times greater than the re-flectivity of base paper.
A particularly advantageous measuring method is to measure the amount of calcium carbonate by measuring the size of the absorption peaks located in its wavelength range 2.5-8 m. Most preferably the size of an ab-sorption peak or peaks located in the wavelength range 3 -7.3 m is meas-ured. The absorption peaks of calcium carbonate are located, for example, at the wavelengths about 5.55 m and 3.95 m.
It is further preferable to measure the amount of kaolin by measur-ing the size of the absorption peaks located in its wavelength area 2,5 11 m.
The method of the invention provides an accurate and useful method for determining paper coating components using reflection measure-ment of the middle infrared range 2.5-12 m. The method is particularly appli-cable to be used for measuring paper coating components i.e. for example measuring kaolin at the wavelength 2.5-11 m, preferably at 8-11 m and/or measuring calcium carbonate at the wavelength 2.5-8 m, preferably at 3.0-7.3 pm. The measurement can generally be carried out at any wavelength in the middle infrared range, for example, at 2.5-12 m.
The method of the invention is applicable for measuring the coating components on a moving base material also from the surface of a roller of a paper coating machine, a roller of a paper machine and/or generally from the surface of a metal plate.
Reflection measurement i.e. measurement where a reflection source and a receiver are on the same side of the object to be measured, can -be carried out using specular reflection measurement whereby the measuring beam is directed onto the surface of the base material as an oblique beam of parallel rays and a parallel reflected beam reflecting from the surface of the base material is detected by a detector i.e. the intensity of the reflected beam is determined as a function of the wavelength.
The invention can be particularly advantageously implemented as diffusion reflection, in which case the measuring beam is directed towards the object to be measured and the intensity of the radiation diffusely reflecting from the object in all directions is determined as a function of the wavelength;
the illumination of the object can also be diffusely implemented.
Reflection measurement of the MIR range provides a very good cor-relation for the amount of coating components, particularly kaolin and carbon-ate and mixtures of these. The correlation is also very good for various base papers and/or cardboards in calibrating the measurement of their coatings.
The MIR range has many advantages compared with the NIR range. In the MIR range high absorptions are achieved for all essential coating components, in addition the peaks are sharp and the scattering is insignificant. The sharp peaks are a desirable property as for the function of detectors of measuring apparatuses based on interference filters, and the small quantity of scattering allows the structural variation of the coating without the calibration suffering.
The fact that the paper industry is willing to start using carbonate-based coat-ings, which cannot be directly measured in the NIR range, increases the sig-nificance of the result.
The use of the method of the invention enables the implementation of measuring apparatuses, which can be used for on-line measurement of pa-per and/or cardboard coating components by paper and coating machines, for on-line measurement of coatings on rollers of paper coating machines or pa-per machines or generally on metal plates and as paper and coating research tools in laboratories. Particularly the use of the method of the invention en-ables the implementation of a small-scale measuring apparatus of the coating amount variation for laboratory use by designing the optics of the apparatus to suit small-scale measurement. In small-scale measurement the size of the measuring area can be 0.1-100 mmz, preferably 0.1-10 mmz, more preferably 0.1-2 mm2, and even smaller than this. Naturally the measuring area can also be larger, for example, of the size about 1 cm2 (n = 1-10 or larger) as is known from prior art. The total amount of the coating to be measured or in small-scale measurement the coating amount to be measured may vary, for example, between 3-40 glm2, preferably 17-25 g/m2.
In the following the invention will be described in greater detail by means of the preferred embodiments with reference to the accompanying drawings, in which Figure 1 is a diagram showing diffusion reflection measurement, Figure 2 is a diagram showing specular reflection measurement, Figures 3 and 4 show reflectivity (%) i.e. the intensity of light meas-ured as a function of a wavelength at the wavelength about 2-11 m, Figures 5 - 9 show coating amounts determined according to the method of the invention as a function of coating amounts determined by labo-ratory measurements and Figure 10 shows small-scale variation of coating amount measured by the method of the invention, the measuring field being 1 mm2.
In Figure 1 a parallel measuring beam B, is directed using a lens 1 obliquely to a paper 2 to be measured, from which a parallel reflected beam B2 is directed using a lens system 3 to a detector 4. The measuring beam B, may consist of light rays having various wavelengths, for example, 2-12 m. The _, ...~..
_._.. ~.,.__.._~_...,.. ._ detector 4 determines the intensity of the beam B2 as a function of a different beam wavelength L The paper 2 may be stationary, for example, in laboratory measurement, or it may be in motion, for example in a paper machine. When the paper 2 moving in the paper machine is being measured the measuring 5 apparatuses are preferably located in a measuring frame traversing in a cross direction in relation to the direction of the paper 2 in which case the measure-ment can be performed at the width of the entire paper 2. The illumination of the paper by the measuring beam B, and the detection of the reflected beam BZ as a function of the wavelength X of the light are known in the art, and will therefore not be described in more detail here. In measuring the MIR range specular optics can preferably be used, the specular optics being known per se and therefore not described in more detail here.
Figure 2 is a diagram showing specular reflection measurement. An incoming beam B, is directed, for example, as a beam of parallel rays at an oblique angle towards the paper 2 and the beam B, of parallel rays reflected from the paper is detected in a manner known in the art using the lens system 3 and the detector 4, the intensity of the reflected beam is detected as a func-tion of the wavelength k of the light.
Figures 3 and 4 graphically show the results of specular reflection measurement performed as shown in Figure 2 compared with the reflectivity of the base paper, a reflection spectrum of kaolin coated paper in Figure 1 and carbonate coated paper in Figure 2 being shown in relation to the spectrum of the base paper. The kaolin peak is shown in Figure 1 at the wavelength 8.5 -10 m and the carbonate peak in Figure 2 at the wavelength 6.5 - 7 m. The peak of styrene butadiene used as a binder is seen around 3 m (Figure 4).
The peaks are very pronounced since the reflectivity of coated paper at the wavelengths of the peaks of the pigments is 5-11 times greater than the re-flectivity of base paper.
A particularly advantageous measuring method is to measure the amount of calcium carbonate by measuring the size of the absorption peaks located in its wavelength range 2.5-8 m. Most preferably the size of an ab-sorption peak or peaks located in the wavelength range 3 -7.3 m is meas-ured. The absorption peaks of calcium carbonate are located, for example, at the wavelengths about 5.55 m and 3.95 m.
It is further preferable to measure the amount of kaolin by measur-ing the size of the absorption peaks located in its wavelength area 2,5 11 m.
An absorption peak of kaolin is located, for example, at the wavelength about 2.7 m.
A series of coating amount measurements of kaolin and carbonate coated papers was performed in order to find out how useful the measuring method is. The measurements showed that the measurement peak response increased to such an extent while the measurement angle of the coating amount increased that a choice had to be made between measurement dy-namics and penetration depth. As a compromise the measurements were performed as diffusion reflection measurements, whereby the calibration showed a better result than specular reflection measurement on account of a good signal-to-noise ratio. Diffusion measurement is not either as sensitive to distance as specular reflection measurement.
The coating amount measurements were performed by a Bomem FTIR spectrometer using a commercial diffusion reflection accessory (Harrick, The Praying Mantis). 'During the measurement a sample was moved over a measurement sample opening using an electric motor, the measuring spot being about 3 mm in diameter. Corresponding components were determined from the measured papers using laboratory measuring methods. In Figures 5- -9 the component amounts determined by the method of the invention are shown on y-axis and the corresponding component amounts determined by laboratory determinations on x-axis. Figure 5 shows the measurement of kao-lin coating coated on wood-containing base paper, Figure 6 the measurement of kaolin coating coated on wood-free base paper, Figure 7 the measurement of carbonate coating coated on wood-containing base paper, Figure 8 the measurement of carbonate/kaolin coating coated on wood-containing base paper and Figure 9 the measurement of kaolin coating coated on wood-containing and wood-free base paper. A standard deviation (SEP) of the de-terminations performed by the method of the invention and a standard devia-tion (SEC) of the determinations performed by laboratory methods were cal-culated from the results; the number of factors describes the number of vari-ables used in the determinations performed by laboratory methods.
Figure 10 shows the variation of the measured small-scale coating amount and the deviation of coating amount measurement when the meas-urement was repeated twice from the same points of 1 mm in diameter.
The preferred embodiments are meant to illustrate the invention without limiting it in any way.
_ . , ___
A series of coating amount measurements of kaolin and carbonate coated papers was performed in order to find out how useful the measuring method is. The measurements showed that the measurement peak response increased to such an extent while the measurement angle of the coating amount increased that a choice had to be made between measurement dy-namics and penetration depth. As a compromise the measurements were performed as diffusion reflection measurements, whereby the calibration showed a better result than specular reflection measurement on account of a good signal-to-noise ratio. Diffusion measurement is not either as sensitive to distance as specular reflection measurement.
The coating amount measurements were performed by a Bomem FTIR spectrometer using a commercial diffusion reflection accessory (Harrick, The Praying Mantis). 'During the measurement a sample was moved over a measurement sample opening using an electric motor, the measuring spot being about 3 mm in diameter. Corresponding components were determined from the measured papers using laboratory measuring methods. In Figures 5- -9 the component amounts determined by the method of the invention are shown on y-axis and the corresponding component amounts determined by laboratory determinations on x-axis. Figure 5 shows the measurement of kao-lin coating coated on wood-containing base paper, Figure 6 the measurement of kaolin coating coated on wood-free base paper, Figure 7 the measurement of carbonate coating coated on wood-containing base paper, Figure 8 the measurement of carbonate/kaolin coating coated on wood-containing base paper and Figure 9 the measurement of kaolin coating coated on wood-containing and wood-free base paper. A standard deviation (SEP) of the de-terminations performed by the method of the invention and a standard devia-tion (SEC) of the determinations performed by laboratory methods were cal-culated from the results; the number of factors describes the number of vari-ables used in the determinations performed by laboratory methods.
Figure 10 shows the variation of the measured small-scale coating amount and the deviation of coating amount measurement when the meas-urement was repeated twice from the same points of 1 mm in diameter.
The preferred embodiments are meant to illustrate the invention without limiting it in any way.
_ . , ___
Claims (10)
1. A method for measuring the components of a coating on a moving base material by infrared measurement, wherein the components of the coating are determined by reflection measurement in the wavelength range 2.5 to 12 µm in such a manner that the amount of calcium carbonate in the coating is determined in the wavelength range 2.5 to 8 µm.
2. A method as claimed in claim 1, wherein the amount of kaolin in the coating is determined in the wavelength range 2.5 to 11 µm.
3. A method as claimed in claim 2, wherein the amount of kaolin is determined by measuring the size of a kaolin absorption peak.
4. A method as claimed in any one of claims 1 to 3, wherein the amount of calcium carbonate in the coating is determined in the wavelength range 3.0 to 7.3 µm.
5. A method as claimed in any one of claims 1 to 4, wherein the amount of calcium carbonate is determined by measuring the size of a calcium carbonate absorption peak.
6. A method as claimed in any one of claims 1 to 5, wherein a reflection spectrum is measured in the wavelength range 2.5 to 12 µm.
7. A method as claimed in any one of claims 1 to 6, wherein the coating components are measured in the measurement area 0.1 to 100 mm2.
8. A method as claimed in any one of claims 1 to 7, wherein the reflection measurement is implemented using specular reflection measurement.
9. A method as claimed in any one of claims 1 to 7, wherein the reflection measurement is implemented using diffusion reflection measurement.
10. A method as claimed in any one of claims 1 to 9, wherein the moving base material, the coating components of which are measured, is paper or cardboard.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI970612 | 1997-02-13 | ||
| FI970612A FI970612A (en) | 1997-02-13 | 1997-02-13 | Method for measuring the components of a paper coating |
| US08/909,287 | 1997-08-11 | ||
| US08/909,287 US5914490A (en) | 1997-02-13 | 1997-08-11 | Procedure for measuring the components of a coating on a moving base material |
| PCT/FI1998/000130 WO1998036264A1 (en) | 1997-02-13 | 1998-02-12 | Method for measuring the components of a coating on a moving base material |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2279904A1 CA2279904A1 (en) | 1998-08-20 |
| CA2279904C true CA2279904C (en) | 2007-09-25 |
Family
ID=26160335
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002279904A Expired - Lifetime CA2279904C (en) | 1997-02-13 | 1998-02-12 | Method for measuring the components of a coating on a moving base material |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0960329A1 (en) |
| JP (1) | JP2001513880A (en) |
| AU (1) | AU5990998A (en) |
| CA (1) | CA2279904C (en) |
| WO (1) | WO1998036264A1 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI108811B (en) * | 1998-02-12 | 2002-03-28 | Metso Paper Automation Oy | Method and apparatus for measuring the amount of coating on a moving surface |
| US6183561B1 (en) * | 1998-12-15 | 2001-02-06 | Honeywell International Inc | Coat weight measuring and control apparatus |
| DE19912500A1 (en) | 1999-03-19 | 2000-09-21 | Voith Sulzer Papiertech Patent | Apparatus to monitor characteristics at a running paper web has optic fibers aligned at lateral line of measurement points to register infra red light waves to be converted into pixels at a detector for computer processing |
| FI115856B (en) * | 2000-02-10 | 2005-07-29 | Metso Automation Oy | Method and apparatus for measuring coating |
| EP2153214A1 (en) | 2007-05-11 | 2010-02-17 | Argos Solutions AS | Apparatus for characterizing a surface structure |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2127541B (en) * | 1982-09-27 | 1986-08-20 | Imp Group Plc | Monitoring sheet material |
| DE3643764A1 (en) * | 1986-12-20 | 1988-06-30 | Lippke Gmbh Co Kg Paul | METHOD FOR SELECTIVE FILLER MEASUREMENT ON RUNNING MATERIAL SHEETS, IN PARTICULAR PAPER SHEETS |
| CA1319273C (en) * | 1988-03-10 | 1993-06-22 | Steven Perry Sturm | Clay sensor |
| US5338361A (en) * | 1991-11-04 | 1994-08-16 | Measurex Corporation | Multiple coat measurement and control apparatus and method |
-
1998
- 1998-02-12 JP JP53539498A patent/JP2001513880A/en active Pending
- 1998-02-12 AU AU59909/98A patent/AU5990998A/en not_active Abandoned
- 1998-02-12 CA CA002279904A patent/CA2279904C/en not_active Expired - Lifetime
- 1998-02-12 EP EP98903050A patent/EP0960329A1/en not_active Ceased
- 1998-02-12 WO PCT/FI1998/000130 patent/WO1998036264A1/en active Application Filing
Also Published As
| Publication number | Publication date |
|---|---|
| WO1998036264A1 (en) | 1998-08-20 |
| AU5990998A (en) | 1998-09-08 |
| CA2279904A1 (en) | 1998-08-20 |
| EP0960329A1 (en) | 1999-12-01 |
| JP2001513880A (en) | 2001-09-04 |
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| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKEX | Expiry |
Effective date: 20180212 |