JPH08101112A - Measuring method for fluidity of coating and dynamic water-retaining property and manufacture of coated sheet of paper using the measuring method - Google Patents

Abstract

PURPOSE: To accurately measure the fluidity and dynamic water-retaining performance of a coating for paper by determining the ratio of elongation of the coating on the paper to elongation of the coating on a film having a low water permeability. CONSTITUTION: A coating is spread over a film having a low water permeability in the state that a shearing force is given, and the elongation of the coating is measured. The same procedure is applied to a sheet of paper, followed by measuring of the elongation (length) of the coating. Then, the ratio of the elongation of the paper coating to the elongation of the film coating is calculated, and thereby, the fluidity and dynamic water-retaining property of the coating are determined. The measuring machine in use may be any one which can spread the coating on the film or paper in the that a shearing force is given, example whereof is an IGT printing suitability testing machine composed of mechanisms for pressurizing. depressurizing, sector gap adjustment, and sector circuitry.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a means for measuring fluidity and dynamic water retention of a coating material for coated paper, and a method for producing coated paper which suppresses the occurrence of bleeding by utilizing the means.

[0002]

2. Description of the Related Art In recent years, in manufacturing coated paper, coating using a blade coater, which is excellent in quality and productivity, has been increasing. The coating speed of the blade coater is 1000 m / min. Before and after was common,
From the viewpoint of improving productivity, 1500 m / min. The above high speeds have been tried by various coaters. Problems that occur during high-speed coating include the phenomenon of bleeding (blade leakage) in addition to the occurrence of strikes and scratches, frequent replacement of blades due to friction, and the like. This is a phenomenon in which paint accumulates behind the blade exit, and a small amount of dry
If it is a dawning, it will fall backward, so it will not affect production or quality. However, wet bleeding adheres to coated paper and causes surface non-uniformity, which can affect the quality of the final product. Regarding this briding, it is considered that the fluidity and water retention of the paint have a great influence, but in actual operation, the conventional knowledge of static water retention is not sufficient, and dynamic water retention is not sufficient. Knowledge on sex is also needed. Dynamic water retention is a physical property defined by the ability to retain water in a sample that is measured with a shearing force applied to the sample to be measured. Examples of means for measuring the dynamic water retention include a method using a dynamic permeability tester, and a method in which the paint immediately after coating is scraped off and the concentration thereof is measured. The latter method, which is actually used in pilot coaters and actual machines, is the mainstream, but (i) the thickness of the coating layer to be scraped off is inaccurate. (Ii) Drying of the paint progresses between the scraping and measurement, and The value is inaccurate. (Iii) It is difficult to measure in real time due to problems such as unreasonable measurement in the manufacturing process.

[0003]

An object of the present invention is to provide means for accurately measuring the fluidity and dynamic water retention of a coating paper coating, and a method for producing coated paper using the means.

[0004]

[Structure] The inventors of the present invention can measure the flow characteristics and dynamic water retention of a coating paper for coated paper by a measuring method using the following measuring method (A), and The inventors have found that they can be used as an index for suppressing the occurrence of bleeding in a paper manufacturing method, particularly a coated paper manufacturing method in which a coating material is applied by a blade coater, and have reached the present invention. Measuring method (A) The paint is stretched on a film having low water permeability in a state where a shearing force is applied, and the elongation (length) of the paint is measured. Then, the same operation as described above is performed on the paper, and the elongation (length) of the paint is measured. The b / a value is calculated based on the following equation (1).

[Equation 2] A first feature of the present invention is a method for measuring the fluidity and dynamic water retention of a coating material, which comprises measuring the fluidity and dynamic water retention of a coating paper coating material by the measurement method (A). Regarding The second feature of the present invention is to measure the fluidity and dynamic water retention of the coating paper coating composition by the measurement method (A).
The present invention relates to a method for measuring the fluidity and dynamic water retention of a paint, which is characterized by using an IGT printability test. A third feature of the present invention is a method for producing a coated paper in which a coating material is coated with a blade coater, wherein the fluidity and dynamic water retention of the coating material are measured before the coating by the first and second measurements. The present invention relates to a method for producing coated paper, which is measured by a method and uses the measurement result as an index for suppressing the occurrence of bleeding. In the present invention, as a measuring machine used for measuring the fluidity and dynamic water retention of the coating paper for coated paper according to the measuring method (A), a film having low water permeability in the state where the coating is applied with shearing force The type is not particularly limited as long as it can be spread on paper or paper. Examples of such a measuring machine include an IGT printability tester including a pressurizing mechanism, a depressurizing mechanism, a disk / sector-gap adjusting mechanism, a sector-rotating mechanism, and the like. Examples of the IGT printability tester include an IGT printability tester as shown in FIG. In the measurement of the measuring method (A) using the tester, a film having low water permeability is set on the circumference of 160 ° sector-1 and the pressurizing mechanism (printing disc) 2 is fixed. The sector (1) is rotated while pressing the film with pressure to measure the elongation (length) of the paint on the film having low water permeability. The paint to be measured is injected between the sector 1 and the pressure mechanism 2 by a suitable injection means, for example, a syringe. The speed for measuring the elongation (length) of the coating material increases from 0 in an accelerated manner, and the maximum value is 100 cm / sec or more, preferably 1 cm.
It is from 00 to 350 cm / sec. Similarly, the above test is carried out using paper to measure the elongation (length) of the paint on the paper.

[0005]

EXAMPLES The present invention will be specifically described below based on examples. Example 1 As a latex of the coating composition shown in Table 1 below, the fluidity and dynamic water retention of the coating composition containing the latexes A, B and C shown in Table 2 below were tested using an IGT printability tester. It was The latex B is a product in which the particle diameter of the latex A is reduced to improve the fluidity of the coating material, and the latex C is a film in which the latex B is provided with water retention property to improve the water retention property. A Choless mixer-disperser was used to prepare the paint. In the test, an IGT printability tester was operated, a film with low water permeability was set, the paint was spread on the film, and then fine paper was set, and the same operation was performed. ) Was performed to calculate the b / a value.

(Equation 3) The high-quality paper was used as the paper, and the PET film was used as the film having low water permeability. However, the film having low water permeability used in the present invention is not limited to the PET film, and the type thereof is not particularly limited as long as the film has water permeability lower than that of paper. The test results are shown in Tables 3 and 4, and the PET film is considered to have no water penetration, and the elongation of the paint is considered to indicate fluidity. On the other hand, in the case of high-quality paper, the elongation is so long that it is difficult to absorb water, which is considered to be related to the water retention capacity and fluidity of the paint. That is, a / b in the table can be regarded as an index of the water retention capacity of the paint. The a / b of latex C is larger than those in Tables 3 and 4. Therefore, the flow characteristics and dynamic water retention are the best.

[0006]

[Table 1]

[0007]

[Table 2]

[0008]

[Table 3]

[0009]

[Table 4]

Example 2 A coating composition shown in Tables 1 and 2 above was used as a blade coater using a valid well jet type fountain type blade coater (manufactured by Ishikawajima Harima Heavy Industries Co., Ltd.). The coated paper was prepared under the conditions as described below. Base paper: Fine paper Paint concentration: Approximately 62-65% (sampled immediately before coating for each coating to confirm the concentration) Coating speed: 500-1500 m / min Blade conditions: Thickness 0.5 mm, blade Degree angle 35 degrees Blade pressure: 0.5 to 1.5 kg / cm Target coating amount: 8 to 10 g / m ^{2 The} test results are shown in Tables 5 and 6 below. Tables 5 and 6
From the results of the above, the latex C in which the water retention property is imparted to the latex B shows the same fluidity as the latex A,
No bleeding occurs up to a higher speed range than Latex A. This can be explained from the measurement result of the water content reflectance. That is, from FIGS. 2 to 4, the straight line of the latex C at the same coating speed is above the latex B.
It is shown that the latex C has a higher water content immediately after coating, and therefore has better dynamic water retention. Further, the high shear fluidity of the coating material of this example was measured, and the results are shown in Table 7 below.
Shown in From Table 7, it can be seen that Latex B having a smaller particle size of Latex A improves the high shear fluidity of the coating material. It is also understood that the latex C having the water retention property imparted to the latex B has a higher high shear fluidity of the paint than the latex B. However, as described above, the occurrence of bridging is less likely to occur in latex C than in latex B. After all, the occurrence of bleeding cannot be suppressed only by improving the high shear fluidity of the latex, and it is considered necessary to improve the dynamic water retention of the latex. Further, the respective coating materials used in this embodiment have different behaviors of occurrence of bleeding even if the other coating conditions are the same as long as the paper quality is different. For example, as shown in Tables 8 and 9 below, among high-quality paper and medium-quality paper, the high-quality paper is less likely to cause bridging. From the above results, consider the coating conditions used for coating, such as coating speed, moisture content (paint solids content), latex type or paper quality, depending on the coating speed used by the coating material used. ,
Whether or not it has the fluidity and dynamic water retention necessary to suppress the occurrence of bleeding is measured before coating using the IGT printability tester, and the measurement results are used. It is possible to easily select a coating that does not cause bleeding immediately after coating with a blade coater.

[0011]

[Table 5] ○ Not generated △ Generation (trace amount) × Generation (ball shape)

[0012]

[Table 6]

[0013]

[Table 7]

[0014]

[Table 8]

[0015]

[Table 9]

[0016]

EFFECTS OF THE INVENTION According to the present invention, there are provided a means for accurately measuring the fluidity and dynamic water retention of a coating material for coated paper, and a method for producing coated paper using the means.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a water content and a reflectance of a coating material I (Latex A) [Numerical values in the drawing are coating amounts (g /
m ² )].

FIG. 2 is a diagram showing a relationship between a coating solid content concentration and a reflectance at a coating speed of 600 m / min.

FIG. 3 is a diagram showing a relationship between a coating solid content concentration and a reflectance at a coating speed of 800 m / min.

FIG. 4 is a diagram showing a relationship between a coating solid content concentration and a reflectance at a coating speed of 1000 m / min.

FIG. 5 is a diagram showing a configuration of an example of an IGT printability tester used in the present invention.

[Explanation of symbols]

 1 sector-2 printing disk 3 pressure rod 4 pressure rod fulcrum 5 pendulum

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Claims (4)

[Claims] 1. A method for measuring the fluidity and dynamic water retention of a coating, which comprises measuring the fluidity and dynamic water retention of a coating paper coating by the following measuring method (A). Measuring method (A) The paint is stretched on a film having low water permeability in a state where a shearing force is applied, and the elongation (length) of the paint is measured. Then, the same operation as described above is performed on the paper, and the elongation (length) of the paint is measured. The b / a value is calculated based on the following equation (1). [Equation 1] 2. The method for measuring the fluidity and dynamic water retention of the coating composition according to claim 1, wherein the measurement by the measuring method (A) is performed using an IGT printability tester. Method of measuring water retention. 3. A method for producing a coated paper in which a coating material is coated with a blade coater, wherein the fluidity and dynamic water retention of the coating material are measured by the measuring method (A) according to claim 1 before coating. Then, the method for producing coated paper, wherein the measurement result is used as an index for suppressing the occurrence of bleeding. 4. The method for producing a coated paper according to claim 3, wherein the measurement by the measurement method (A) is a measurement by an IGT printability tester.