JPH08260395A - Production of pigment-coated paper and paperboard using rod type coater - Google Patents

Abstract

PURPOSE: To provide a method for producing sheets of pigment-coated paper and paperboard excellent in uniformity in distribution of coating amount, smoothness, white paper gloss, printing glass and mottling resistance adaptability of the printed surface. CONSTITUTION: The sheets of pigment-coated paper and paperboard are produced by using a rod type coater equipped with a rod provided with grooves having 5×A to 150μm depth or the grooves, 5×A to 500μm groove pitch Pμm and 0 to 0.3×Pμp m ridge length based on Aμm surface roughness of base paper for coating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing pigment-coated paper (including paperboard, the same applies hereinafter), and more particularly, uniformity of coating amount distribution, smoothness, white paper gloss, printing gloss, and mottling resistance of the printing surface. The present invention relates to a method for producing a pigment-coated paper having excellent suitability.

[0002]

2. Description of the Related Art Pigment coated paper is compared to unpigmented paper
White paper gloss, printing gloss, ink receptivity, ink color density,
Since the vividness of the ink color is remarkably excellent, the growth has been remarkable in recent years with the progress of visualization in all fields. Therefore, the coating apparatus, which is an important apparatus for manufacturing the pigment coated paper, is being improved day by day.

Currently, as the coating apparatus, a blade coater type is exclusively used for coating paper, and a rod coater type is mainly used for paperboard. These coating devices are preferably used because high-concentration paints can be applied, the drying load is small and the quality of the finished coated paper is excellent, and high-speed coating is possible.
The main reason is that since the surface of the excess coating material coated on the coated base paper is scratched so as to be smoothed, it has excellent smoothness, white paper gloss, printing gloss, and the like.

However, because of this scraping method, the uniformity of the coating amount distribution is poor, and especially when the surface roughness of the coated base paper is rough, it deteriorates the surface feeling of the blank paper and causes the mottling of the printed surface. Cause a lot of. As measures against this, the conventional measures have been mainly to change the coating composition, improve the texture of the coated base paper, etc., but have not yet reached a satisfactory level.

When an air knife is used as a coating device, the uniformity of the coating amount distribution is increased and the mottling resistance of the printing surface is improved. Since only high-viscosity paint can be applied, high-concentration paint cannot be used. Therefore, there is a drawback that the coated paper quality such as smoothness, white paper gloss and printing gloss is poor.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a method for producing a pigment-coated paper having excellent coating amount distribution uniformity, smoothness, white paper gloss, printing gloss, and printing surface anti-mottling suitability. It is intended.

[0007]

Means for Solving the Problems As a result of intensive studies by the present inventors, in order to obtain a coated paper which has a uniform coating amount distribution and which is excellent in smoothness, white paper gloss, printing gloss, and anti-mottling property of a printed surface. Found that a rod-type coating device equipped with a rod having a groove having a size corresponding to the surface roughness of the coated base paper should be used.

That is, with respect to the surface roughness Aμm of the coated base paper,
The groove depth is 5 × A to 150 μm, and the groove pitch P μm is 5.
The coating amount distribution is obtained by applying the pigment coating composition using a rod-type coating device equipped with a rod having a groove of × A to 500 μm and groove length of 0 to 0.3 × P μm. It was found that a pigment-coated paper having excellent uniformity, smoothness, white paper gloss, printing gloss, and anti-mottling suitability of the printing surface can be produced, and the present invention has been completed.

The surface roughness adopted here is the value of the parker.
The pressure measured by the print surface is 20 kg. The parker print surface has a thickness of 51 μm.
It has a measuring head in which a measuring ring having a length of m and a length of 100 mm is incorporated, and this ring is pressed against the surface whose roughness is to be measured, and low pressure air is sent from the inside of the ring to the outside in this state. At this time, the resistance of the air flow flowing between the ring and the sample is measured by a variable area flow meter, and this value is converted into roughness. (The details are described in Kappa Gikyo, 1995.2, 189 pages.)

The rod type coating apparatus is of a type in which a roll for supporting the coated base paper is provided and the rod can be pressed against the coated base paper. (A schematic diagram is shown in FIG. 1.) This type of coating apparatus is suitable for the present invention because it can coat even if the viscosity of the coating is high. The size of the groove of the rod is such that the depth of the groove is 5 × A to 15 with respect to the surface roughness Aμm of the coated base paper.
It is preferable to have a groove having a groove pitch of 0 μm, a groove pitch Pμm of 5 × A to 500 μm, and a groove crest length of 0 to 0.3 × Pμm.
FIG. 2 shows an example of how to measure the groove depth, pitch, and groove crest length.

When the groove depth and pitch are smaller than 5 × A μm, the effect of uniform coating amount distribution and suitability for mottling cannot be recognized, and the groove depth is 150 μm and the pitch is 500 μm.
If it is larger than m, the effect of uniform coating amount distribution is not recognized, or the coating amount becomes excessive and lowers. Therefore, it is necessary to drastically reduce the coating concentration. Therefore, there arises a problem that the glossiness of white paper and the glossiness of printing are reduced. If the length of the groove is longer than 0.3 × Pμm, the coating streaks frequently occur, which is impossible. As a means for forming the groove, a grooveless rod may be carved with a groove or a wire may be wound. Therefore, the shape of the groove is not particularly limited, the depth is 5 × A to 150 μm, the pitch is 5 × A to 500 μm, and the groove crest length is 0 to 0.3 × P.
It may be μm.

The reason why the coating amount distribution is uniform in the grooved rod is considered as follows. When coating with a blade or a grooveless rod, the coating amount of the convex portion of the coated base paper is small and the coating amount of the concave portion is large. This difference in coating amount causes unevenness. Therefore, as one means for eliminating the nonuniformity, increasing the coating amount of the convex portion can be considered. That is, in the case of the grooved rod, if the groove is formed in the convex portion, the coating amount is increased and the nonuniformity is reduced. In this case, when the surface roughness of the coated base paper becomes rough, the difference in the coating amount between the concave portion and the convex portion widens and the nonuniformity increases. To improve this, it is necessary to increase the coating amount of the convex portion. This is considered to be the reason why the roughness of the coated base paper determines the size of the groove that can make the coating amount distribution uniform.

Further, since the coating amount is large in the groove portion and the coating amount is small in the groove mountain portion, if the coating material does not move from the portion having a large coating amount to the portion having a small coating amount,
The difference in coating amount remains as coating streaks. It is presumed that this is because if the length of the groove crests becomes too long with respect to the length of the groove, the coating material cannot be moved from the portion having a large amount of coating to the portion having a small amount of coating, resulting in coating streaks.

There is no particular limitation on the pigment coating composition as a paint, and as the pigment, clay, calcium carbonate, titanium dioxide, aluminum hydroxide, satin white, magnesium carbonate, calcium sulfate, barium sulfate, amorphous silica, Examples of binders such as styrene-based plastic pigments and urea-based plastic pigments include starch, casein, polyvinyl alcohol, soybean protein, styrene-butadiene latex, acrylic latex, vinyl acetate latex, and urethane latex. In addition, a dispersant, a pH adjuster, a water retention agent, a lubricant, an antifoaming agent, an antiseptic, a fluorescent dye, a dye, a coloring pigment, a water resistant agent and the like can be used if necessary.

The type of coated base paper and the papermaking method are not particularly limited, and the papermaking method may be either a neutral paper method or an acidic paper method. Any pulp may be used for papermaking, and chemical pulp, mechanical pulp, waste paper pulp, synthetic pulp and the like can be used. In addition, if necessary, an internally added sizing agent, a fixing agent, a paper strengthening agent, a drainage retention improving agent, an internally added filler, a dye, a defoaming agent,
A slime control agent or the like may be used.

The present invention can be applied to a multi-layer coating as a coating method, but the effect of the present invention is exhibited when it is used for the surface layer, and even when it is used for coating a layer below the surface layer. There is no. The surface roughness of the coated base paper in this case is the roughness of the layer below the surface layer. There is no particular limitation on the apparatus for applying the layer below the surface layer, and it is not limited to a blade coater, a rod coater, a roll coater, a gate roll coater, and an air knife coater. -Ter, gravure coater, size press, champion coater, simsizer, etc.

[0017]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.
All the compounding parts are effective solids. Moreover,% is based on weight.

Example 1 Preparation of coating material: 40 parts by weight of Ultra White 90 (Kre, manufactured by Engelhard Co.) as a pigment composition, 90% by weight of Cavital
(Heavy calcium carbonate, manufactured by I-C-International Co., Ltd.) 40 parts by weight, Brilliant 15 (light calcium carbonate, manufactured by Shiraishi Kogyo Co., Ltd.) 20 parts by weight were used together with Aron T-40 (dispersion). Agent, manufactured by Toagosei Chemical Co., Ltd.) 0.10 part by weight, caustic soda 0.1 part by weight, Formaster AP (antifoaming agent, manufactured by San Nopco Co.) 0.1 part by weight was added to the dispersion water. -Stirring was carried out for 30 minutes with a less disperser to obtain a pigment slurry having a concentration of 70%.

Next, 100 parts by weight of this pigment slurry was used as a binder composition for a pen fod gum 290.
(Hydroxyethyl etherified starch, manufactured by Penford Co.)
3 parts by weight, 12 parts by weight of SN-307 (carboxyl-modified SBR latex, manufactured by Sumitomo Dow Co., Ltd.) were used, diluted water was added, and the mixture was stirred for 10 minutes to obtain a coating composition having a concentration of 61%.

Coating: 60 g / m 2 of this coating composition
m ² and surface roughness 4.26 μm coated on high quality coated base paper 10
g / m ² to become like, the groove depth 50μm, pitch 200μ
CLC6000 coater (Sensor & Simula) equipped with a rod having a groove of m and groove length of 0 μm.
coating products manufactured by Tion Products). The coating speed was 1000 m / min, and immediately after coating, the pigment-coated paper was obtained by drying with an infrared heater attached to this coater.

Calendar treatment, quality evaluation: This pigment coated paper was subjected to a humidity control treatment according to JIS P 8111, and the coated surface was treated with a metal under the conditions of a metal roll surface temperature of 100 ° C. and a nip linear pressure of 100 kg / cm. It was placed on a roll and subjected to super calendering. The number of processing times is two. Again JIS P 8
The coated paper was subjected to humidity control treatment in accordance with No. 111, and the uniformity of paint distribution, smoothness, white paper gloss, printing gloss, and mottling resistance of the printing surface were evaluated. The results are shown in Table-2.

Example 2 Preparation of paint: Caobrite (cray, sea
(Manufactured by Le Co., Ltd.) 60 parts by weight, Softon 2200 (heavy calcium carbonate, manufactured by Shiraishi Calcium Co., Ltd.) 40 parts by weight, and as a binder composition MS-4600 (urea phosphate esterified starch,
5 parts by weight of Nippon Shokuhin Kako Co., Ltd., and 16 parts by weight of JSR0668 (carboxyl-modified SBR latex, manufactured by Nippon Synthetic Rubber Co., Ltd.) were carried out in the same manner as in Example-1, and the concentration was 63%.
A coating composition for undercoat of was obtained. Next, as a pigment composition, 45 parts by weight of Hydrafine 90 (Kre, manufactured by Huber), 40 parts by weight of Brilliant 15 and chronos KA-
15 parts by weight of 10 (titanium dioxide, manufactured by Titanium Industry Co., Ltd.), 2.5 parts by weight of MS-4600 as a binder composition, L-
1410 (carboxyl-modified SBR latex, manufactured by Asahi Kasei Co., Ltd.) was carried out in the same manner as in Example 1 except that the amount was 59% to obtain a top coating composition.

Coating: This undercoating coating composition
5 g / m ² of which become coated amount 8 g / m ² on uncoated white paperboard, CLC6000 was fitted with a non-grooved rod co - data - except that the coating at a coating speed of 400 meters / minute using Example −
The same procedure as in 1 was carried out to obtain a coated base paper with an undercoat layer. The surface roughness of this coated base paper was 4.53 μm. Then, the coating composition for top coating is applied to this coated base paper in an amount of 11 g.
/ M ² to become like, the groove depth 30μm, pitch 100μm,
C equipped with a rod having grooves with groove lengths of 10 μm
A pigment-coated paper board was obtained in the same manner as in Example 1 except that the coating was performed at a coating speed of 400 m / min using an LC6000 coater.

Calendar processing, quality evaluation: Example-1
The calender process was performed and the quality was evaluated in the same manner as in. The results are shown in Table-2.

Examples-3 to 4 The quality evaluation was performed in the same manner as in Example-1 except that the changes were made according to Table-1 in Example-1. The results are shown in Table-2.

Example-5 The quality evaluation was performed in the same manner as in Example-2 except that the changes were made according to Table-1 in Example-2. The results are shown in Table-2.

Comparative Examples-1 to 5 The quality evaluation was performed in the same manner as in Example-1 except that the changes were made according to Table-1 in Example-1. The results are shown in Table-2.

Comparative Example-6 The coating apparatus in Example-1 was changed to a test air-knife coat.
A quality evaluation was performed in the same manner as in Example-1 except that the tester was used. The results are shown in Table-2. Coating speed is 100m /
Minutes.

Comparative Examples-7 to 9 The quality evaluation was performed in the same manner as in Example-2 except that the changes were made in accordance with Table-1 in Example-2. The results are shown in Table-2.

Comparative Example 10 The quality evaluation was performed in the same manner as in Example-2, except that the coating apparatus for topcoating in Example-2 used a test air knife knife coater. The results are shown in Table-2. Coating speed is 1
00 m / min.

[0031]

[Table 1]

Test Method I-Roughness of base paper: Measured with a parker print surface.
The measurement pressure is 20 kg.・ Uniformity of coating amount: Ammonium chloride solution (Ammon chloride; 1
0 parts by weight, isopropyl alcohol; 10 parts by weight, water; 1
(00 parts by weight), the coated sample is dipped for 15 minutes, heated over an electric heater to heat the coated base paper, and the coating unevenness of the coating layer is visually raised. The uniformity of the coating amount distribution is visually evaluated from this carbonized sample. ⊚: No unevenness observed at all ◯: Slight non-uniformity observed △: Significant non-uniformity ×: Severe non-uniformity observed

Test Method II White Paper Gloss: Measured according to JIS P 8142. -Print gloss: 0.5 on the RI printability tester (manufactured by Akira Seisakusho)
Supply ml of red ink and knead for 2 minutes to print a coated paper sample. After the ink is dried, the gloss of the printed surface is JIS P 8
Measure according to 142.・ Mottling: An RI-II type printability tester was supplied with 0.5 ml of yellow ink for the first color and 0.5 ml of red ink for the second color, kneading for 2 minutes, printing a coated paper sample, and printing the red ink. The density unevenness is visually evaluated. In addition,
The second color is printed 30 seconds after the first color is printed. ⊚: No unevenness observed at all ○: Slight non-uniformity observed △: Significant non-uniformity ×: Severe non-uniformity ・ Coating streaks: Visual evaluation of coated surface ○; No coating streaks x; coating streaks ・ Smoothness: J. Measured with Tappi No5 Oken smoothness tester.

[0034]

[Table 2]

[0035]

As can be seen from the above examples and comparative examples, according to the manufacturing method of the present invention, the groove depth and the minimum value of the pitch are determined based on the surface roughness of the coated base paper, and the groove height is determined based on the pitch. By maintaining the rod size within the specified range of the maximum value of the length, the coated paper with excellent coating amount distribution uniformity, smoothness, white paper gloss, printing gloss, and printing surface mottling resistance , Coated paperboard is obtained.

[Brief description of drawings]

FIG. 1 is a schematic view of a rod-type bar coating device, which is one in which a bar and a backing roll sandwich a coated paper and a pressure mechanism is provided.

FIG. 2 is an explanatory sectional view of a bar, showing how to take shapes and dimensions of each part.

Front page continuation (72) Inventor Kenji Endo 2-3-2 Higashishinozaki, Edogawa-ku, Tokyo Honshu Paper Co., Ltd.

Claims (1)

[Claims] 1. A method for producing pigment-coated paper and paperboard using a rod-type coating device, comprising:
m, the groove depth is 5 × A to 150 μm, the groove pitch Pμm is 5 × A to 500 μm, and the groove crest length is 0 to 0.3.
A method for producing a pigment-coated paper and a paperboard, which comprises using a rod-type coating device equipped with a rod having a groove of × P μm.