JPH09257443A - Online measuring method for substance surface property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable online measurement of a less smooth region by adjusting an illuminating angle of a shed beam to a normal line on a surface of running coated paper for printing and a light reception angle of normally reflected light with respect to a normal line of an object to be measured in a specific range. SOLUTION: Light from a light source 1 is shed with an illuminating light angle of 78 to 85 degrees with respect to a normal line 10 on a surface 11 of an object to be measured with a reflector 2a changed in position and angle as a reflector 2b. In order to apply normally reflected light of 78 to 85 degrees corresponding to each illuminating angle to a condenser lens 4, a reflector 3a is changed in position and angle as a reflector 3b, a light flux is received by a CCD sensor 5, and an intensity distribution 12 of the reflected light is detected and output as an electric signal for measuring surface property of paper. When the illuminating angle of a light beam with respect to a normal line of the object to be measured is thus made to be 78 degrees or more, a sufficient reflected light amount can be obtained with less smooth coated paper, thereby enabling measurement of brilliance and smoothness. When the illuminating angle exceeds 85 degrees, scattering of the reflected light is remarkable, lowering measuring accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-line measuring method for material surface properties of a sheet, particularly a coated paper for printing, in which a base paper made of pulp is coated with a pigment, and in particular, matte paper whose gloss is suppressed.

[0002]

2. Description of the Related Art Paper is a thin fiber obtained by adhering fibers, that is, pulp, taken from a plant to each other. In addition, the paper contains a filler called clay. Depending on the type of pulp used as the raw material for paper, the presence or absence of filler, type, etc.
The surface condition remarkably differs depending on the manufacturing method. In some cases, a pigment (calcium carbonate / kaolin) and an adhesive (latex / starch) are applied to the surface of the finished paper by a coating machine, and a super calendar is applied to increase gloss and smoothness. The main use of paper is for printing, but there are various types of paper such as coated paper with a smooth surface or coated paper with a rough surface, depending on the purpose.

The most important point in the production of coated paper for printing is to efficiently produce paper having smoothness, glossiness and coated surface quality according to each application. Beck (JISP 8119), Smoother, Sheffield, Parker Print Surf, Bentsen, Chapman, Williams, Gurley, Woken type smoothness meter are all used as measuring devices for detecting the smoothness of the paper surface which is important for the coated paper. The measurement method based on the air leakage method is common. The measurement method based on the smooth air leak method is susceptible to the influence of the air gap of the coating layer surface of the paper and the inside of the coated paper or the air permeability of the paper, and may not necessarily accurately reflect the human visual evaluation. Moreover, it is impossible to re-measure with the same sample during measurement because it damages the object to be measured. In addition, when finishing with a super calender, usually at the production site, in order to confirm whether the desired smoothness and glossiness are obtained, the line is temporarily stopped and the web is cut as a sample and the above-mentioned smoothness measuring device is used. , Measurement is performed and quality control is performed, but the line operating at high speed is stopped and a lot of damaged paper is generated, resulting in poor efficiency.

Optical non-contact type surface 3 using a stylus three-dimensional roughness measuring device or a laser light source as a measuring device for accurately and very accurately detecting the surface smoothness of the coated paper for printing.
There is a dimensional roughness measuring instrument. However, in these methods, the workability is very poor because the measurement time is very long and the measurement area is small.

In such a situation, a light emitting diode is used as a light source as a sensor that enables simple measurement, and an incident angle is fixed at a predetermined angle with respect to a normal line of an object to be measured, and a line CCD sensor is used as a regular reflection light receiving element. There is a non-contact optical measurement method (for example, Japanese Patent Laid-Open No. 63-315938) in which the peak light amount of specular reflection light and the magnitude of dispersion of specular reflection light are used as a measure of glossiness and smoothness. By using this method, the smoothness and glossiness of the surface of the coated paper for printing can be measured online easily and accurately without damaging the object to be measured in the paper manufacturing process.

[0006]

However, in this method, since the irradiation angle of the light source is fixed at a predetermined angle of 75 ° with respect to the normal to the object to be measured, the measurement value with the stylus three-dimensional roughness meter measuring device is measured. (Center Surface Average Roughness) Correlation cannot be obtained with a measured object such as matte paper having Ra = 10.0 μm or more. The reason is that the amount of light in the regular reflection direction is extremely reduced and the peak light amount cannot be obtained in the measurement of the object to be measured with low smoothness by the method, and the dispersion width of the regular reflection light is diffused in an extremely wide range. Detection in the direction of specular reflection becomes impossible, and measurement in a low smooth area is impossible.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to easily measure the glossiness and smoothness of a low-smooth region of a printing coated paper online, and as a result, The present invention has been completed by finding that simple and accurate measurement is possible by measuring in the range of 78 to 85 degrees.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the measuring principle and outline of a measuring apparatus used in the present invention. Irradiation angle of light from the light source (1) with respect to the normal line (10) of the DUT surface (11) is 78 degrees (6) or more and 85 degrees by changing the position and angle of the reflection plate (2a) like (2b). Irradiation is performed at less than (8), and the reflection plate (3a) is set to (3b) so that the specular reflection light of 78 degrees (7) or more and less than 85 degrees (9) corresponding to each irradiation angle is applied to the condenser lens (4). The position and angle are changed as shown in), the intensity distribution (12) of the reflected light is detected by the line CCD sensor (5), and the condensed light flux is output as an electric signal to measure the surface property of the paper. I do. An overall view of the case where the measuring device is mounted on a moving measured object is shown in FIG. 2. A measuring device (14) having the measuring principle of FIG. 1 is installed on the moving measured object (13). Perform the measurement. The measuring device can be attached to the lower part of the object to be measured, in which case the surface properties of the surface and the back surface of the object to be measured can be simultaneously measured.

When the glossiness of printed coated paper is measured, the irradiation angle with respect to the normal of the measured object is 75 ± 0.5 °, which is specified in JIS P8142, but low smooth paper such as matte paper. In the case where a sufficient amount of reflected light is not obtained and the irradiation angle of the light source with respect to the normal line of the object to be measured is set higher than 78 degrees, the measurement value (center plane average roughness) of the stylus three-dimensional roughness measuring instrument is measured. ) Even with a low-smoothness coated paper having Ra = 10.0 μm or more, a sufficient amount of reflected light can be obtained and glossiness and smoothness can be measured. However, when the measurement is performed at an irradiation angle of more than 85 degrees, the scattering of reflected light becomes remarkable, and accurate reflected light cannot be obtained, resulting in a decrease in measurement accuracy. Further, in order to install the light source at an irradiation light angle of 78 degrees or more and less than 85 degrees with respect to the normal to the surface of the object to be measured, the light source is measured by a light projecting means as disclosed in JP-A-63-315938. Because there is a danger of contact with things,
The light source is located above the web, and the light emitted from the light source is applied to the reflection plate once and the reflected light is applied to the DUT. The specularly reflected light is reflected by the reflection plate located on the light receiving side and received by the light receiving device. With this method, it is possible to prevent the device from being in contact with the object to be measured and prevent the device from becoming large.

As the light source, one which does not change in light quantity with time is desirable. Normally, the C-light source specified in JIS P8142 is used. However, an A-light source such as a small light bulb, an infrared light emitting diode, a laser light emitting element or the like is used. It doesn't matter. It is desirable that the light emitted from the light source has a finite irradiation area with a clear boundary on the object to be measured by an optical focusing method. The size of this irradiation area is usually increased by increasing the irradiation angle, but the vertical length is 5 to 20 m.
An oval shape with m and a width of 10 to 30 mm is suitable. The reflected light reflected on the object to be measured is condensed on the light receiving element via the reflecting plate and the condenser lens.

It is desirable that the light receiving element does not change its sensitivity with time, and the line CCD sensor used in the present invention is a sensor that detects electromagnetic waves having a wavelength of about 0.2 μm to 30 μm as an electric signal. Although it can be classified into a type and a thermal effect type, since the present invention is a measurement of the amount of light reflected on the surface of a substance, a quantum effect type was used. It can be roughly divided into electromotive force types. Photoelectron emission type sensors include a phototube that directly converts photoelectrons into a signal current and a photomultiplier tube that incorporates a secondary electron multiplying function. A typical photoconductive type is a CdS cell, and a photovoltaic sensor includes a photodiode, a phototransistor, an avalanche photodiode, and the like. Although any of the above may be used, in the present invention, a line C in which a large number of photodiodes of the photovoltaic sensor are arranged from the viewpoint of shape.
A CD sensor was used.

The light beam reflected in the regular reflection direction is a line CCD
The light is focused on the sensor with an opening angle of 5 ° or less, and an electromotive force is generated by the action of photovoltaic power, which is taken out to the external terminal. It is possible to output this as it is to an analog recorder, but preferably it is A / D converted by a computer,
Store it in the internal memory or save the data in a recording medium. As a result, the luminous flux incident on the line CCD sensor is divided into 2048 elements in the width direction and the intensity is divided into 256 gradations and converted into a voltage value corresponding to the amount of light, and the reflected light intensity distribution ( 14) is obtained. The height from the bottom of the distribution to the peak position was defined as the peak height (15), and the distribution width corresponding to the height position from the bottom was defined as the dispersion width (16). The value obtained by dividing the height position by the peak height was added to the beginning of the position width to give the name of the dispersion width.

When the integrated value of the obtained reflected light intensity distribution is Y and the integrated value of the regular reflected light intensity distribution from the glass surface of the refractive index 1.567 standard plate is X, the glossiness (%) is given by the following formula. Stipulated.

[0014]

## EQU1 ## Glossiness (%) = (Y / X) × 100 X: Integral value of intensity distribution of regular reflection light from the glass surface of the standard plate having a refractive index of 1.567 Y: Intensity distribution of regular reflection light from paper Integrated value

As for the smoothness, a value obtained by dividing the quarter position width value (t) of the obtained reflected light intensity distribution by the dispersion width t ₀ is used as a measure of the smoothness.

[0016]

[Number 2] smoothness = t / t ₀ t: 1/4 Position width of the obtained reflected light intensity distribution t _0: Distributed bottom width

The reason why the 1/4 position width from the bottom of the peak height of the reflected light peak waveform is used as an index for smoothness is from experimental confirmation. When the smoothness was compared by changing the method of taking the dispersion width, the peak height was divided into four equal parts and
When the dispersion width at four positions was used as an index of smoothness, as shown in FIG. 4 showing the relationship with the Ra corresponding to each position width and the correlation coefficient, the Ra value of the stylus three-dimensional roughness meter was obtained. This is because it had the highest correlation with.

The present invention is characterized in that the irradiation angle and the reflected light angle of the light source are set to 78 degrees or more and less than 85 degrees.
As a result, it became possible to measure the surface smoothness of the coated paper for printing having a measured value (center surface average roughness) Ra of 10.0 μm or more measured by a stylus three-dimensional roughness measuring instrument. In particular, the correlation was very high, and the correlation coefficient r was 0.99 or more. Further, the glossiness also has a high correlation with the 75-degree specular glossiness test method, and it has become possible to easily measure the smoothness and glossiness of low-smoothness paper, which has been troublesome until now.

[0019]

EXAMPLES The effects of the present invention will be described below with reference to examples, but the present invention is not limited thereto. The various measured values in the examples are obtained by the following methods. A) White paper glossiness: Measured at an angle of 75 degrees according to JIS P8142. (%) A) Three-dimensional surface roughness: Stylus three-dimensional roughness meter measuring device SE-3
The Ra value calculated by AK (Kosaka Laboratory) was used.
(Μm)

As the web used in the present invention, generally used matte paper is used. The matte base paper containing the pulp shown below is coated with a blade coating device so that the absolute dry coating amount becomes 15 g / m ^2. The solid concentration below is 62
% Of the coating liquid was applied at a coating speed of 1000 m / min, and the coated paper obtained was treated under a supercalender under each condition, and the surface property of each sample was measured by this apparatus. Pulp blending NBKP: 300 LBKP: 700 Coating liquid blending Commercial heavy calcium carbonate: 20 parts Commercial light calcium carbonate: 30 parts Commercial secondary kaolin: 50 parts Commercial polyacrylic acid-based dispersant: 0.1 parts Commercial phosphate esterified starch : 2 parts Commercially available styrene-butadiene latex: 15 parts Sodium hydroxide: 0.15 parts Solid content concentration: 62% In the following Examples and Comparative Examples, the coating liquid is prepared with the above-mentioned composition unless otherwise specified. The amount applied is usually the same as above.

The preparation of samples used in the present invention will be described below.

Sample 1 A roll of offset printing paper obtained under the above conditions was supercalendered under the following conditions. Calender line pressure: 200 kg / cm Heat roll temperature: 90 ° C. Calender speed: 800 m / min Nip frequency: 10 times

Sample 2 A sample was prepared under the same conditions as those of sample 1, except that super calendering was performed under the following conditions. Calender line pressure: 200 kg / cm Heat roll temperature: 60 ° C Calender speed: 800 m / min Nip count: 10 times

Sample 3 A super calendar was applied under the following conditions. Samples were prepared under the same conditions as Sample 1 except for the above. Calender linear pressure: 200 kg / cm Heat roll temperature: 90 ° C Calender speed: 800 m / min Nip frequency: 2 times

Sample 4 A sample was prepared under the same conditions as in sample 1, except that super calendaring was performed under the following conditions. Calender line pressure: 180 kg / cm Heat roll temperature: 60 ° C Calender speed: 800 m / min Nip frequency: 2 times

Sample 5 A sample was prepared under the same conditions as in sample 1, except that super calendaring was performed under the following conditions. Calender line pressure: 160 kg / cm Heat roll temperature: 60 ° C Calender speed: 800 m / min Nip frequency: 2 times

Sample 6 A sample was prepared under the same conditions as in sample 1, except that the offset printing paper obtained by the above method was not calendered.

Example 1 The sensor of the present invention was installed at a fixed point near the bottom exit of the super calender, and each winding sample obtained by the above method was run at a speed of 800 m / min to make it smooth and glossy online. The measurement was performed. The sensor condition is that the irradiation light angle and the light reception angle with respect to the normal to the surface of the object to be measured are set to 78 degrees, and the glossiness is the value obtained by Equation 1,
The smoothness is a value obtained by the equation 2.

Example 2 Except that the irradiation light angle and the light receiving angle with respect to the normal to the surface of the object to be measured were set to 82 degrees, the glossiness was the value obtained by the equation 1, and the smoothness was the value obtained by the equation 2. Was measured in the same manner as in Example 1.

Example 3 Except that the irradiation light angle and the light receiving angle with respect to the normal to the surface of the object to be measured were set to 85 degrees, the glossiness was set to the value obtained by the equation 1, and the smoothness was set to the value obtained by the equation 2. Was measured in the same manner as in Example 1.

Comparative Example 1 Except that the irradiation light angle and the light receiving angle with respect to the normal to the surface of the object to be measured were set to 75 degrees, the glossiness was set to the value obtained by the equation 1, and the smoothness was set to the value obtained by the equation 2. Was measured in the same manner as in Example 1.

Comparative Example 2 Except that the irradiation light angle and the light receiving angle with respect to the normal to the surface of the object to be measured are set to 77 degrees, the glossiness is the value obtained by the equation 1, and the smoothness is the value obtained by the equation 2. Was measured in the same manner as in Example 1.

Comparative Example 3 Except that the irradiation light angle and the light receiving angle with respect to the normal to the surface of the object to be measured were set to 87 degrees, the glossiness was set to the value obtained by the equation 1, and the smoothness was set to the value obtained by the equation 2. Was measured in the same manner as in Example 1.

Each sample was measured by the above-mentioned examples and comparative examples, and Table 1 shows the measured values of the stylus three-dimensional roughness meter and JIS gloss meter of each sample. Tables 2 and 3 show the three-dimensional stylus, respectively. It is a comparison of the roughness meter measurement value and JIS gloss meter measurement value and the measurement value in each Example and a comparative example. Table 4 shows a probe three-dimensional roughness meter and JI in each example and comparative example.
It is a comparison of the correlation coefficient of each S gloss meter measurement value.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

[Table 3]

[0038]

[Table 4]

[0039]

EFFECTS OF THE INVENTION The measured values obtained in the present invention are all values that well represent the surface glossiness and smoothness of the coated paper for printing, and online measurement of a low smoothness region which was impossible by the conventional method. Became possible.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a measurement principle.

FIG. 2 is an overall measurement diagram.

FIG. 3 is a reflected light intensity distribution.

FIG. 4 is a comparison of the correlation with a stylus three-dimensional roughness meter depending on how the dispersion width is taken.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source 2a Irradiation side reflection plate 2b Reflection plate after movement 3a Reflection side reflection plate 3b Reflection plate after movement 4 Condensing lens 5 Line CCD sensor 6 Irradiation angle 78 degrees 7 Reflection angle 78 degrees 8 Irradiation angle 85 degrees 9 Reflection angle 85 Degree 10 Normal line 11 Object to be measured 12 Reflected light intensity distribution 13 Object to be measured 14 Measuring instrument used in the present invention 15 Peak height 16 Dispersion width

Claims (1)

[Claims] 1. An optical measurement method for simultaneously measuring the surface glossiness and smoothness of a coated paper for printing simultaneously on-line, comprising: an irradiation angle of an irradiation light source with respect to a normal line of a running coated paper surface; The acceptance angle for the normal of the DUT is 78
Using a device that is equipped with a mechanism that can be varied within a range of not less than 85 degrees and less than 85 degrees, the reflected light from the measured object is received and detected by the line CCD sensor, and the integrated value of the amount of the reflected light is measured. It is used as an index of the gloss of a product, and the size of the dispersion width at the 1/4 position from the bottom of the peak height of the reflected light is used as a measure of smoothness. A measurement method for simultaneous measurement of sex.