JP2880106B2 - Matte lightweight coated paper and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a light-weight and bulky
The present invention relates to a method for producing a matte lightweight coated paper having excellent opacity and rigidity, high surface smoothness, and gloss after printing, and a matted lightweight coated paper produced by the method.

[0002]

2. Description of the Related Art In recent years, in the field of visual magazines such as photographic magazines in publishing, and in the fields of flyers and catalogs in commercial printing, surface smoothness and printing are not inferior to conventional coated paper. While having high quality, relatively inexpensive lightly coated paper and lightweight coated paper are suitable for the user's low cost trend, and the market growth is large. In recent years, these coated paper users have become increasingly lighter in weight in recent years, for example, due to an increase in the number of mail-order catalog sheets and an increase in postage.

[0003] In addition, the needs of users have been diversified, and the need for matte lightweight coated paper having a smooth surface and excellent printability has been increasing even though the surface is dull and damp and moist. .

[0004] On the other hand, in general, the lighter the weight, the lower the paper thickness and the loss of bulk, resulting in a paper without stiffness and reduced opacity, giving a low-grade feeling.
The page is hard to turn and difficult to read.

[0005] From the above background, to produce a lighter product while maintaining the same print quality, that is, to reduce the coating amount, or to increase the bulkiness and opacity with the same coating amount, There is an increasing demand for stiff coated paper.

[0006] Generally, to produce bulky coated paper,
The most effective means is to make the base paper before coating bulky. One of the general methods is to make a base paper using a raw pulp having a high freeness that has been beaten as weakly as possible. However, in this case, although a bulky paper is obtained, the surface smoothness and the barrier property are inferior at the same time, so that the coating liquid soaks into the base paper and the printing quality of the coated paper is deteriorated. Therefore, if the calender linear pressure of the stencil machine is enhanced to improve the smoothness, the contradictory result of loss of bulk will result.

Another method is to provide a surface smoothness and a barrier property of the base paper by minimizing a decrease in bulk due to the calendering treatment, in other words, to increase the bulk while maintaining the same smoothness. More specifically, as such a method, a heat calendering treatment using a high-temperature roll or the application of steam immediately before calendering treatment is described (Japanese Patent Application Laid-Open Nos. 4-31695 and 6-73685). But,
Although these also improved smoothness, it was not recognized that sufficient bulk was obtained.

[0008]

SUMMARY OF THE INVENTION In view of the above situation, an object of the present invention is to solve the above-mentioned drawbacks in the matte lightweight coated paper manufacturing process, thereby reducing the weight and bulk of the coated paper.
An object of the present invention is to provide a method for producing a matte light weight coated paper which is excellent in opacity and rigidity (stiffness), has high smoothness and high gloss after printing, and a matte light weight coated paper obtained by the method.

[0009]

Means for Solving the Problems As a result of intensive studies on the above-mentioned problems, the present inventors have found that in a production method of coating a base paper with a coating liquid twice, a polyvinyl alcohol as a main component and a foam stabilizer are used. The undercoating coating liquid containing a water-proofing agent and a foaming agent having a foaming ratio of 3 times or more was coated on a base paper, dried, coated with a topcoating pigment coating liquid, and dried to arrive at the present invention. .

Hereinafter, features of the present invention will be described in detail.

[0011] The present invention provides an undercoating coating solution containing polyvinyl alcohol as a main component and containing a foam stabilizer and a water-proofing agent as foam having a foaming ratio of 3 times or more, and is coated on a base paper and dried. It becomes possible to form a foam-like or sponge-like barrier layer, and as a result, even after coating with a topcoat pigment, is lighter and bulkier than conventional coated paper, opacity, excellent in stiffness, smoothness, It is characterized in that matte coated paper having excellent gloss after printing is obtained. This is because a bulky wet coating layer is formed on the base paper surface by coating the base paper with the foamed undercoat coating liquid,
In the subsequent drying step, concentration and partial foam breakage proceed, and after drying, an undercoating layer having a large number of appropriate fine voids is formed, and the penetration of the topcoating pigment coating liquid into the base paper is controlled. In addition, since the bulky undercoating layer covers the irregularities of the base paper, the surface smoothness of the undercoating paper is improved, and the surface properties after the overcoat pigment coating is also improved.

When the foam stabilizer is not added to the undercoating coating liquid, the stability of the foam is insufficient, so that the foam is easily broken in the drying step. The water resistance of the layer becomes insufficient, and during the overcoating, bubbles are easily broken by water brought in from the overcoating pigment coating liquid. The amount of the water-proofing agent used is 1 to 3 in terms of the solid content concentration of the undercoat coating liquid.
% Is preferred. When the expansion ratio is less than 3 times, the fluidity of the undercoating coating liquid is not much different from the case where no foaming is performed, and the penetration of the coating liquid into the paper easily proceeds, and foam breakage occurs. When bubbles are generated in this way, a bulky undercoat layer is not obtained, and no improvement in surface smoothness after overcoat pigment coating is observed.

The foam stabilizer used in the present invention is also called a foam stabilizer, and is a surfactant used for the purpose of prolonging the generated foam. As the foam stabilizer, lauryl alcohol, sodium laurate, lower aliphatic alcohol, ammonium stearate, dodecyl alcohol,
Laurylic acid diethanolamide, amine oxide and the like can be used. The use amount of the foam stabilizer is preferably 2 to 4% in terms of the solid content concentration of the undercoat coating liquid. Addition of a thickening agent is also effective for stabilizing the foam, and is preferably used in combination with the foam stabilizer. As the thickener, carboxymethyl cellulose, polyethylene oxide, methyl cellulose, hydroxymethyl cellulose, sodium polyacrylate, sodium alginate and the like can be used. In addition, as a water-proofing agent, formaldehyde, glyoxal, dialdehyde starch, urea-formaldehyde resin, melamine-formaldehyde resin, polyamide urea-formaldehyde resin,
Ketone resins, polyamide epichlorohydrin resins, ammonium zirconium carbonate, borax and the like can be used.

In the present invention, it is preferred that the base paper is manufactured using pulp beaten to a Canadian standard type freeness of 400 to 500 ml. If the freeness is lower than 400 ml, the bulk tends to be reduced before the undercoating. If it is higher than 500ml,
Barrier formation due to undercoating becomes insufficient, and the overcoating pigment coating liquid tends to seep too much, resulting in a decrease in surface properties and printability.

The coating amount of the undercoat can be adjusted by adjusting the concentration of the liquid, the expansion ratio and the operation of the coating device. However, the coating amount is 2 per side from the effect on the barrier property and the surface smoothness.
g / m ² or more is preferred. When the amount is more than 5 g / m ² , the undercoat layer is easily deformed, so that the undercoat layer is easily scratched.
Paper defects are likely to occur.

The composition for coating a topcoat pigment according to the present invention comprises 5 heavy calcium carbonate having an average particle size of 0.5 to 1.5 μm.
It preferably contains 0 to 80% by weight and 20 to 50% by weight of kaolin. When the average particle size of the heavy calcium carbonate is less than 0.5 μm or when the blending amount is less than 40% by weight, the glossiness of the white paper becomes high, and it is difficult to obtain a matte surface. When the average particle size exceeds 1.5 μm or when the compounding amount exceeds 80% by weight, the pigment orientation is inferior and the surface properties such as smoothness and surface feel of the product are reduced, and the ink receptivity is lowered. The print gloss tends to decrease due to the decrease.

The adhesive used in the composition for coating a topcoat pigment of the present invention may be a styrene / butadiene-based adhesive or a styrene / butadiene-based adhesive.
Various copolymers such as acrylic, ethylene / vinyl acetate, butadiene / methyl methacrylate, vinyl acetate / butyl acrylate, and synthetic systems such as polyvinyl alcohol, maleic anhydride copolymer, and methyl methacrylate acrylate copolymer Commonly known adhesives such as adhesives, oxidized starch, etherified starch, esterified starch, enzyme-modified starch and cold-water-soluble starch obtained by flash-drying them, casein, natural adhesives such as soybean protein, etc. Can be These adhesives are used in an amount of 10 per 100 parts by weight of pigment.
About 30 parts by weight is preferable. Further, various auxiliaries blended with ordinary pigments for coated paper, such as commonly used dispersants, thickeners, water retention agents, defoamers, water-proofing agents, and colorants, may be used in combination.

The foam of the undercoating coating liquid thus prepared is coated and dried by a roll coater, a blade coater, a rod coater or the like. In addition, the top coat pigment coating liquid is a blade coater, an air knife coater, a roll coater, a curtain coater, which are generally used in the production of coated paper.
The coating is performed by a coating device such as a chaplex coater, a bar coater, and a gravure coater. Among them, it is more preferable to use a coating device such as an air knife coater or a curtain coater that does not generate pressure on the base paper during coating. .

The coating amount of the topcoat pigment coating composition on the base paper is preferably in the range of 7 to 15 g / m ² in terms of dry weight per side from the viewpoint of weight reduction of the coated paper to be obtained and quality of blank paper.

The base paper is not particularly limited except that pulp having a Canadian standard freeness specified in the claims of the present invention is used, and a paper base base paper having a basis weight of 30 to 60 g / m ² is preferable.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The matte lightweight coated paper of the present invention is used for forming a base coating liquid containing polyvinyl alcohol as a main component and containing a foam stabilizer and a waterproofing agent into foam having a foaming ratio of 3 times or more. It is manufactured by coating and drying a base paper and then applying a topcoat pigment coating liquid and drying. Canadian standard type freeness of pulp used for production of base paper (JIS P812
1) is preferably in the range of 400 to 500 ml. The pigment in the topcoat pigment coating liquid has an average particle size of 0.1.
It is preferable to contain 50 to 80% by weight of heavy calcium carbonate of 5 to 1.5 μm and 20 to 50% by weight of kaolin.

[0022]

The present invention will be described in detail below with reference to examples and comparative examples of the present invention, but the present invention is not limited to these examples. Parts and% used in the examples below are parts by weight and% by weight, respectively, unless otherwise specified. The results are shown in the table.

Quality Evaluation Method (1) Pulp Freeness: Canadian standard freeness was measured in accordance with JIS P-8121.

(2) Foaming expansion ratio: expressed as the ratio of the volume of the liquid before foaming to the volume of the foam after foaming.

(3) Calcium carbonate average particle diameter: Using a light transmission type particle size distribution analyzer SHC5000 manufactured by Seishin Enterprise, the 50% point of the weight cumulative distribution was measured as the average particle diameter.

(4) Glossiness of blank paper: JIS P-8142
Was measured at an angle of 75 degrees.

(5) Smoothness: JAPAN Tappi
No5: Measured by Oken type smoothness tester.

(6) Glossiness after printing: Printing was performed at a rotational speed of 40 rpm using a RI-11 type printing tester and 0.35 cc of Sakata Inks offset printing ink (trade name: Diatone GSL Red). After leaving, 75
The glossiness was measured.

(7) Opacity: Measured with a Hunter whiteness tester according to JIS P-8138.

(8) Rigidity: In accordance with JIS P-8143, the longitudinal direction was measured with a Clark stiffness tester.

Example 1 As an undercoat coating liquid, polyvinyl alcohol (trade name: Kuraray Povar 217,
(Kuraray Co., Ltd.) 10% (solid content), foam stabilizer (trade name: SN Form 200, manufactured by San Nopco Co., Ltd.)
A foaming composition containing 3% (solid content) and 2% (solid content) of a waterproofing agent (trade name: Glyoxal, manufactured by Nippon Synthetic Chemical Co., Ltd.) was prepared, and a continuous foaming machine (trade name: FINE) was prepared.
FOAM (manufactured by Suehiro Chemical Co., Ltd.) until the volume was four times that before foaming.

Furthermore, 60 parts of heavy calcium carbonate (trade name; Hydrocarbo 90, manufactured by Shiraishi Calcium Co., Ltd.) having an average particle diameter of 0.6 μm, kaolin (trade name: Ultra White 90) 40 parts of Engelhard Co., Ltd. and a dispersant (trade name: Alon T-
40, manufactured by Toa Gosei Chemical Co., Ltd.) and dispersed in water to a solid concentration of 70% using a Cowles dispersing machine. Product name: MS # 4600, Nippon Shokuhin Kako Co., Ltd.
4 parts and styrene / butadiene copolymer latex (trade name: JSR 0696, manufactured by Nippon Synthetic Rubber Co., Ltd.) 10
Were mixed to prepare a top coat composition having a solid content of 64%.

First, the foam of the undercoat coating liquid is mixed with pulp blended NBK.
P65%, LBKP35%, Canadian standard freeness 460
Using a roll coater on a base paper having a basis weight of 50 g / m ² , which was made from 100 ml of raw pulp, a solid content of 3 g per side was used.
/ M ² on both sides and dried, and then a top coat pigment coating liquid is further applied with a blade coater at a solid content of 10 g / m 2 per side.
² was coated on both sides and dried.

Example 2 When preparing an undercoat coating liquid, polyvinyl alcohol (trade name; Kuraray Povar H)
L-1203, manufactured by Kuraray Co., Ltd.) 8% (solid content concentration),
Oxidized starch (trade name: Mermaid M-200, manufactured by Shikishima Starch Co., Ltd.) 2% (solid content), foam stabilizer (trade name: SN Form 200, manufactured by San Nopco Co., Ltd.) 3%
(Solid content concentration), waterproofing agent (trade name: glyoxal,
A coated paper was obtained in the same manner as in Example 1 except that 2% (solid content) manufactured by Nippon Synthetic Chemical Co., Ltd. was used.

Example 3 When preparing an undercoat coating solution, polyvinyl alcohol (trade name: Gohsenol GH)
-17, manufactured by Nippon Synthetic Chemical Co., Ltd.) 10% (solid content), carboxymethyl cellulose (trade name: Sunrose F-50MC, manufactured by Nippon Paper Industries) 0.5% (solid content), foam stable 2.5% (solid content), water-proofing agent (trade name: Glyoxal, manufactured by Nippon Synthetic Chemical Co., Ltd.) 2
% (Solid content), except that a coated paper was obtained in the same manner as in Example 1.

Example 4 Pulp was blended with LBKP75
%, SGP 25%, Canadian standard type Coated paper was obtained in the same manner as in Example 1 except that a base paper having a basis weight of 50 g / m ² made of raw pulp having a freeness of 470 ml was used.

Comparative Example 1 A coated paper was obtained in the same manner as in Example 1 except that the undercoating coating liquid was applied in a liquid state without foaming.

Comparative Example 2 A coated paper was obtained in the same manner as in Example 1 except that the undercoat coating liquid was foamed until the volume became twice as large as before the foaming.

[Comparative Example 3] A water-proofing agent was not used in the undercoating coating solution, and the average particle size was 2.0 μm in the overcoating pigment coating solution.
Heavy calcium carbonate (trade name; Escalon # 150)
Coated paper was obtained in the same manner as in Example 1 except for using S.K.

[Comparative Example 4] LBKP 100%, Canadian standard type Free pulp having a freeness of 300 ml was weighed 5
A base paper of 0 g / m ² was used, a water-proofing agent was not used in the undercoating coating solution, and the average particle size was 0.6 in the overcoating pigment coating solution.
μm heavy calcium carbonate (trade name: Hydrocarb 9)
0, manufactured by Shiraishi Calcium Co., Ltd.) 80 parts, kaolin (trade name: Ultra White 90, Engelhard Co., Ltd.) 2
A coated paper was obtained in the same manner as in Example 1 except that 0 part was used.

[0041]

[Table 1]

As is clear from the table, Examples 1 to 4 are low in density, bulky, high in smoothness, high in gloss after printing, high in opacity, and excellent in rigidity. On the other hand, Comparative Examples 1 to 4 have high density, low smoothness, low gloss after printing, and are inferior in opacity and rigidity. Particularly, in Comparative Example 3, gloss after printing was extremely low because coarse heavy calcium carbonate having an average particle size of 0.2 μm was used in the overcoat pigment coating liquid. Further, in Comparative Example 4, since the Canadian standard type freeness of the raw pulp was as low as 300 ml, the density was already high at the base paper stage and the rigidity was low. Inferior.

[0043]

As described above, the matte light weight coated paper manufactured by the method for manufacturing a matte light weight coated paper of the present invention is lightweight,
Because of its bulkiness, excellent opacity and rigidity (stiffness), high smoothness and high gloss after printing, its product value is extremely large.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) D21H 1/32

Claims (4)

(57) [Claims] 1. A method for producing a matte light weight coated paper in which a base paper is coated with a coating liquid twice, wherein an undercoat coating liquid containing polyvinyl alcohol as a main component and containing a foam stabilizer and a waterproofing agent. Into a foam with a foaming ratio of 3 times or more, coated on the base paper,
A method for producing a matte light-weight coated paper, which comprises drying and then applying a topcoat pigment coating liquid and drying. 2. Canadian standard freeness (JIS P812)
2. The method for producing a matte light-weight coated paper according to claim 1, wherein the base paper produced by using 1 to 400 ml of pulp is used. 3. The topcoat pigment coating liquid contains at least a pigment and an adhesive, and the pigment has an average particle diameter of 0.5 to 0.5.
The method for producing a matte light-weight coated paper according to claim 1, wherein the content is 50 to 80% by weight of heavy calcium carbonate of 1.5 µm and 20 to 50% by weight of kaolin. 4. A matt lightweight coated paper having a bulky undercoating layer containing polyvinyl alcohol as a main component, a foam stabilizer and a waterproofing agent, and having fine voids, and a topcoating pigment coating layer.