JP3371422B2 - Matte coated paper - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a matte coated paper for printing, and more particularly to a light weight dull matte coated paper.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand (hereinafter referred to as "visualization") to strongly convey the content visually to printed matter by making extensive use of photographs and patterns and further colorizing the same. On the other hand, there is a strong demand for reducing the weight of printed matter in terms of resource saving, transportation and mailing costs. These two demands are contradictory, and the coated paper of a grade suitable for visualization has a large base paper basis weight and a large coating amount, which does not meet the demand for weight reduction. Coated paper is roughly classified into high gloss coated paper and matte coated paper. High-gloss coated papers are art papers and super art papers that have been conventionally used for high-quality printing, and the finish of printing is glossy with both white paper gloss and printing gloss. The matte coated paper has a dull or matte tone depending on the white gloss and printing gloss. Matte is a flat and calm print with low gloss on both the white and printed sides, and dull is an intermediate between glossy and matte that the white gloss is low but the print gloss is high. is there. The dull tone is preferred for its calm and high-class feeling compared to the conventional gloss tone, and the demand for it has been increasing in recent years. For example, as darart paper, the basis weight is 157 g /
m ² , double-sided coating amount 40 to 50 g / m ² , density (tightness) 1.
The typical quality of 18 g / cm ³ dull art paper is 75 °
Gloss 35%, 60 ° printing Gloss 55% (4 color overprinting part) (Printing and Paper 188 pages Paper Industry Times Company 19
Published in 1996).

In order to reduce the weight of the dull matte coated paper, for example, if the basis weight and the coating weight of the dull art paper are halved to a total basis weight of 60 g / m ² , the printing glossiness becomes Remarkably decreased to about 10 to 30%, the opacity decreased and the risk of show-through problems increased, and the rigidity was insufficient and the paper passing to the printing machine became unstable and stable. The operability of printing is lost. Total basis weight 6
If the coating amount of the coating layer is increased in order to improve the printing glossiness at 0 g / m ^2, the basis weight of the base paper will have to be reduced by that much, and the opacity and rigidity will become insufficient more and more do not become.
If the basis weight of the base paper is increased in order to improve the opacity and the rigidity to a practical level, the coating amount must be extremely reduced this time, resulting in insufficient surface coverage and printing gloss. An unclear image with extremely low degree will result. Further, as a method of improving the opacity, a method of internally adding an inorganic filler such as titanium dioxide having a large opacity to the base paper is known, but when the inorganic filler is internally added, the density of the base paper increases conversely and the rigidity is increased. Will fall. As a method for reducing the weight of the base paper while maintaining the opacity and the rigidity, Japanese Patent Publication No. 52-118116
Japanese Patent Publication discloses a method of blending hollow synthetic organic material capsules, and a synthetic organic foaming filler (for example, trade name EXPANSEL, which is foamed by heat of a dryer during papermaking,
A method of blending Nihon Philite Co., Ltd. is known. However, these methods are difficult to obtain stable operating conditions such as drying conditions during paper making, and are not suitable for varieties that require mass production. In addition, a method of adding fine fibrillated cellulose has been proposed in JP-A-8-13380, although it is not a filler. However, in this method, it is necessary to separately adjust the fine fibrillated cellulose, and further, the freeness of the pulp at the time of papermaking needs to be CSF 400 ml or more, preferably CSF 500 ml or more, but the stockness containing a large amount of mechanical pulp adjusts the freeness. It is difficult to do so, and industrial application to medium-quality paper using mechanical pulp is not possible.

As described above, it is impossible to obtain a light weight dull coated paper having desired characteristics by simply applying the conventional technique.

[0005]

In view of such a situation, an object of the present invention is to have a relatively high printing glossiness in spite of low opacity and rigidity, which has opacity and rigidity suitable for practical use. To provide a light weight dull matte coated paper.

[0006]

Means for Solving the Problems As a result of intensive studies on the above problems, the present invention contains mechanical pulp as a pulp for papermaking in an amount of 10% by weight or more, and amorphous silica as a filler in an amount of 3 to 12% by weight based on the weight of paper. A coated paper in which a coating layer of a pigment having a particle size distribution in which pigment particles are contained in an amount of 65% or more in the range of 0.4 to 4.2 μm on a volume basis is provided on the contained base paper, By treating the paper with a soft nip calender with a rigid roll temperature of 150 ° C or higher, the density is low and the paper thickness is low, so that the opacity and rigidity can be maintained in a practically usable state. Is still low, you can get an image with relatively high printing glossiness,
The present invention has been completed by finding out that the above problems can be solved. The pulp constituting the base paper must contain mechanical pulp in an amount of 10% by weight or more. Since mechanical pulp has more rigid fibers than chemical pulp, base paper containing mechanical pulp is less likely to be crushed by various pressures applied in the papermaking process, and becomes bulky as a whole, increasing the amount of voids inside the base paper, The opacity is improved and at the same time the rigidity is increased. Among the mechanical pulps, ground pulp has a large contribution to lowering the density and can be preferably used. If the amount of mechanical pulp is less than 10% by weight, sufficient opacity and rigidity cannot be obtained even if the filler and calender conditions are optimized. The mechanical pulp is preferably 60% by weight or less of the papermaking pulp from the viewpoints of whiteness and coating suitability. There are no particular restrictions on the type of mechanical pulp tree, but gumwood, maple, birch and the like tend to have low density in the base paper due to the coarse fibers. Pulps other than mechanical pulp are not particularly limited, and chemical pulp and waste paper pulp can be used. In particular, the use of waste paper pulp is preferable in that the mechanical pulp in the waste paper can be used as the mechanical pulp of the present invention and that resources are effectively used.

The filler is 3 to 12% by weight of the amorphous silicate in the base paper based on the weight of the paper under the above pulp conditions.
Include. If it is less than 3% by weight, the coated base paper does not have a low density, and even if the pulp blending and calendering conditions are optimized, a sufficiently low density base paper cannot be obtained. On the other hand, when the amount is more than 12% by weight, the number of filler particles per pulp weight increases and the probability of interfiber bonding being hindered increases, which is suitable for printing workability even after the coating layer is provided. The surface strength cannot be maintained. The bulk specific gravity of the amorphous silicate is preferably 0.2 to 0.8 g / ml,
More preferably, it is 0.4 to 0.7 g / ml. When a coated base paper containing an amorphous silicate having a bulk specific gravity of less than 0.2 g / ml is used, the surface strength of the coated paper itself is lowered. When a coated base paper containing an amorphous silicate having a bulk specific gravity of more than 0.8 g / ml is used, the density of the coated paper becomes high and it becomes difficult to obtain a desired low-density bulky paper. The amorphous silicate of the present invention is a light metal salt of hydrous silicic acid, and examples thereof include hydrous sodium silicate, hydrous aluminum silicate, hydrous sodium aluminum silicate, hydrous calcium silicate, hydrous magnesium silicate and the like. . These amorphous silicates may be used alone or in combination of two or more kinds.

The basis weight of the base paper is 3 that is used for general coated paper.
About 0 to 400 g / m ² can be appropriately used, but the effect of the present invention becomes remarkable when the opacity and paper-passing property of the base paper become 80 g / m ² or less, particularly 2
It is 5 to 60 g / m ² .

The coating pigment may have a volume ratio of 0.4 to 0.4.
It is important to use pigments with a particle size distribution of 65% or more in the 4.2 μm range. 0.4 to 4 on a volume basis.
When a pigment containing 65% or less of particles falling within the range of 2 μm and having a large volume distribution particle size is used, the glossiness of the white paper is high, but a pigment having a large volume distribution particle size is used. Compared with the case of the above, the printing surface has a low gloss and the base paper coverage is also inferior. Therefore, when a pigment with many particles with a small volume distribution particle size is used and the coating amount is reduced, even if the basis weight of the base paper is increased, it is a bulky matte coated paper with excellent white paper appearance and printability. Is difficult to manufacture. Further, when a pigment containing 65% or less of particles falling within a range of 0.4 to 4.2 μm on a volume basis and having a large volume distribution particle diameter is used, printing glossiness and base paper coverage are good. However, the glossiness of the white paper becomes too low compared to the case of using a pigment with many particles with a small volume distribution particle size, and it also produces a bulky matte coated paper with excellent white paper appearance and printability. Is difficult to do.

The kind of the pigment used in the present invention is not particularly limited as long as it satisfies this volume standard distribution, and kaolin, clay, delaminated clay, and heavier that have been conventionally used as coating pigments. Calcium carbonate, light calcium carbonate, talc, titanium dioxide, barium sulfate, calcium sulfate, silicic acid, silicates, colloidal silica, inorganic pigments such as satin white, organic pigments such as plastic pigments, these pigments are required They may be used alone or in combination of two or more. In the present invention, in order to obtain desired properties such as coating suitability of paint and quality of coated paper, it is usually preferable to use a plurality of pigments in combination, in which case the particles as a whole have a particle size of 0.4- It is important that the particle size distribution is 65% or more in the range of 4.2 μm. The pigment of the present invention is characterized by a particle size distribution, and has a relatively large particle size distribution in comparison with commonly used coating pigments. It is used by selecting it or classifying it and using it within the range defined in the present invention. By doing this,
Even with a low coating amount, it is possible to increase the coverage of the surface of the base paper, and it is possible to obtain a relatively high glossiness on the printing surface despite the low glossiness of the white paper.

The coated paper thus obtained must be surface-finished by a high temperature soft nip calender consisting of an elastic roll and a rigid roll heated to 150 ° C. or higher. If the water content of the coated paper is appropriate, the higher the rigid roll temperature, the lower the nip pressure or the shorter nip residence time can be used to smooth the base paper or coating layer.
If the temperature is lower than 150 ° C, this effect cannot be obtained. To obtain white paper gloss and print gloss comparable to those obtained using conventional super calenders with a high temperature soft nip calender, a low nip pressure and short nip residence time can be used. Layer and base paper have low density, high opacity, rigidity and low density and bulky matte coated paper. Furthermore, processing speed is faster than conventional super calender and re-rolling frame is omitted. As a result, it can be efficiently produced and has excellent operability.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The matte coated paper of the present invention comprises a mechanical pulp, a pulp for papermaking such as a chemical pulp, a waste paper pulp and the like.
0% by weight or more is blended and beaten to obtain a pulp slurry, in which amorphous silicate is contained in an amount of 3 to 12% by weight based on the weight of base paper
To make paper stock. The filler may be mixed with a small amount of talc, kaolin, heavy calcium carbonate, light calcium carbonate and titanium oxide in addition to the amorphous silicate for the purpose of adjusting the papermaking suitability and strength characteristics of the stock slurry.

If necessary, chemicals usually used in the papermaking process, such as a paper-strengthening agent, a sizing agent, a defoaming agent, and a coloring agent, are added to these paper materials to make a paper. The papermaking method is not particularly limited, using a Fourdrinier machine including a top wire and the like, a circular net machine, a combined machine of these both, a Yankee dryer machine, an acidic papermaking machine, a neutral papermaking machine,
Paper is made using an alkaline papermaking method. Also size press,
A base paper pre-coated with starch, polyvinyl alcohol, etc. using a gate roll coater or a pre-metering size press, or a base paper pre-coated with one or more coating solutions containing a pigment and an adhesive can also be used. .

On the base paper, a paint containing an adhesive and, if necessary, additives added with a pigment alone or mixed which satisfies the particle size distribution of the present invention is applied. Adhesives are styrene / butadiene-based, styrene / acrylic-based, ethylene / vinyl acetate-based, butadiene /
Synthetic adhesives such as methyl methacrylate-based, vinyl acetate / butyl acrylate-based copolymers, polyvinyl alcohol, maleic anhydride copolymers, acrylic acid-methyl methacrylate-based copolymers, etc .; casein, soybean protein, synthetic protein Proteins such as; oxidized starch, positive starch,
Urea phosphate esterified starch, hydroxyethyl etherified starch and other etherified starch, dextrin and other starches; carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose and other cellulose derivatives, etc. Used by choice. These adhesives are used in an amount of 5 to 50 parts by weight, preferably 10 to 30 parts by weight, per 100 parts by weight of the pigment.

Further, as additives to be added as necessary, various additives such as a dispersant, a thickener, a water retention agent, a defoaming agent, a water resistance agent, and a coloring agent, which are usually added to coated paper pigments. Auxiliary agents are used as appropriate.

The prepared coating solution is applied on both sides of one or more layers on the base paper using a bar coater, roll coater, air knife coater, reverse roll coater, curtain coater, size press coater, gate roll coater, etc. Work. The coating amount is determined according to the desired characteristics, but in the case of the present invention, the basis weight of the base paper is approximately 60 g /
For m ^2, when the ^{6~10g / m 2, 40g / m} 2 5
With a small coating amount of about 8 g / m ² , sufficient coverage and
Print surface glossiness can be obtained.

As the method for drying the wet coating layer, various types of dryers such as the above-mentioned heating cylinder, heated hot air dryer, gas heater dryer, electric heater dryer, and infrared heater dryer are used alone or in combination.

In the present invention, after the coating liquid is applied to the above-mentioned coated base paper and dried, it is pressure-finished by a high temperature soft nip calender having a rigid roll temperature of 150 ° C. or higher. A metal roll is preferable as the rigid roll. In the high temperature soft nip calender, not only the temperature but also the nip residence time are important. From this point, the roll equivalent diameter is 300 in actual operation.
mm or more, Shore D hardness of elastic roll 80 to 100,
It is preferably 85 to 95 and has a roll equivalent diameter of 500 m.
When converted to m, the paper feeding speed is 400 to 3000 m / min.
Linear pressure 30-500 kg / cm, coating moisture before calendar 5
It is preferable to carry out the treatment with a calender nip number of 2 or more at 8%. The equivalent roll diameter is shown by AVLyons et al. In the following formula (1990 TAPPI Finishing and Conver
ting, P5) Refers to the equivalent diameter of the roll. (Roll equivalent diameter) = (Soft roll diameter) × (Chilled roll diameter) / {(Soft roll diameter) + (Chilled roll diameter)}

[0019]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Unless otherwise specified, parts and% in the examples represent% by weight.

The matte coated papers obtained were tested according to the following evaluation methods. (Blank glossiness) The glossiness was measured according to JIS P 8142. (Printing glossiness) Using a RI-II type printing tester, printing was performed using 0.30 cc of a sheet-fed process ink manufactured by Toyo Ink Mfg. Co., Ltd. (trade name: TK Hychoko MZ), and left after standing for one day and night. The surface of the printed matter according to JIS P
8142. (Density) Measured according to JIS P 8118. (Strength) Using a RI-II type printing tester, 0.40 cc of a special ink (trade name SMX Tack Grade 15) manufactured by Toyo Ink Mfg. Co., Ltd. was used for printing, and then lined to remove the peeled state. The visual evaluation was made according to the following criteria. ⊚: Very good, ◯: Good, Δ: Slightly inferior, ×: Inferior (opacity) Measured based on JIS P 8138,
The evaluation was performed based on the following criteria. ◯: Good, Δ: Slightly inferior (rigidity) Measured according to JIS P8143, and evaluated according to the following criteria. ◯: Good, Δ: Slightly inferior [Example 1] [Preparation of coating liquid] Engineered kaolin (ECLIPS650 manufactured by Engelhard Co., volume distribution particle size 0.40
˜4.20 μm: 65.3%) 80 parts, 20 wt parts of fine ground calcium carbonate (FMT-90 manufactured by Phimatech Co., volume distribution particle size 0.40 to 4.20 μm: 71.9%) 20 parts ( Volume distribution particle size 0.40 to 4.20 μm: 6
6.6%) was added with 0.2 part of sodium polyacrylate as a dispersant as a dispersant and dispersed by a serie mixer to prepare a pigment slurry having a solid content concentration of 70%. The pigment slurry thus obtained was added to a non-thickening type styrene-butadiene copolymer latex (glass transition temperature 15 ° C.,
10 parts of a gel content of 75%) and 6 parts of hydroxyethyl etherified starch (PG295 manufactured by Penford Co.) were added, and water was further added to obtain a coating solution having a concentration of 60%. [Base paper] 4 g by weight of water-containing sodium aluminum silicate (bulk specific gravity 0.4 g / ml) as a filler, 6 parts by weight of talc, and 30 g by weight of mechanical pulp as a pulp for papermaking, basis weight 46 g / M ² of medium quality paper was used as the coated base paper. [Production of coated paper] The above-mentioned base paper is coated on both sides with a blade coater at a coating speed of 800 m / min so that the coating amount per one side is 7 g / m ² . The paper was dried so that the water content was 5.5%. [Calendar] Next, a roll equivalent diameter of 400 mm, a metal roll temperature of 160 ° C., an elastic roll Shore hardness of 85,
A matte coated paper was obtained by performing a soft nip calendering process under the conditions of a calendering speed of 650 m / min, a linear pressure of 40 kg / cm and a calender nip number of 2 nip. [Example 2] 3% by weight (bulk specific gravity 0.4 g / ml) of water-containing sodium silicate as a filler, 7 parts by weight of talc as a filler, and 11% by weight of mechanical pulp as a pulp for papermaking A coated paper was obtained in the same manner as in Example 1 except that the quality paper was used as the coated base paper. [Example 3] A medium quality paper containing 10% by weight (bulk specific gravity: 0.4 g / ml) of hydrous sodium aluminum silicate as a filler per unit weight of paper and 40% by weight of mechanical pulp as a papermaking pulp Example 1 except that it was used as
A coated paper was obtained in the same manner as in. [Example 4] A mechanical pulp obtained from newspaper waste paper pulp as a pulp for papermaking, containing 4% by weight (bulk specific gravity: 0.4 g / ml) of water-containing sodium aluminum silicate as a filler and 6 parts by weight of talc. A coated paper was obtained in the same manner as in Example 1 except that a medium-quality paper containing 30% by weight of was used as the coating base paper. Example 5 As a pigment, kaolin produced in Brazil (Capim DG manufactured by Rio Capim Co., volume distribution particle size 0.40 to 4.2)
Pigment consisting of 70 parts of 0 μm: 68.4%) and 30 parts of coarse-grained heavy calcium carbonate (FMT-75 manufactured by Phimatech, volume distribution particle size 0.40 to 4.20 μm: 69.5%) (volume distribution) Particle size 0.40 to 4.20 μm: 68.7
%) As a dispersant, 0.2 part of sodium polyacrylate was added and dispersed by a serie mixer to prepare a pigment slurry having a solid content concentration of 70%.
A coated paper was obtained in the same manner as in. Comparative Example 1 1% by weight (bulk specific gravity 0.4 g / ml) of water-containing sodium aluminum silicate as a filler, 9 parts by weight of talc, and 15% by weight of mechanical pulp as a pulp for papermaking A coated paper was obtained in the same manner as in Example 1 except that the quality paper was used as the coated base paper. [Comparative Example 2] A base paper coated with a medium-quality paper containing 13% by weight (bulk specific gravity: 0.4 g / ml) of hydrous sodium aluminum silicate as a filler and 17% by weight of mechanical pulp as a papermaking pulp. Example 1 except that it was used as
A coated paper was obtained in the same manner as in. [Comparative Example 3] 5% by weight (bulk specific gravity: 0.4 g / ml) of hydrous aluminum silicate as a filler, 5 parts by weight of talc as a filler, and 8% by weight of mechanical pulp as a pulp for papermaking A coated paper was obtained in the same manner as in Example 1 except that the quality paper was used as the coated base paper. [Comparative Example 4] Coating was carried out in the same manner as in Example 1 except that a medium-quality paper containing 10 parts by weight of talc as a filler and 20% by weight of mechanical pulp as a pulp for papermaking was used as a base paper for coating. Got the paper. [Comparative Example 5] A coated paper was obtained in the same manner as in Example 1 except that the roll temperature of the soft calendar of Example 1 was changed to 120 ° C. [Comparative Example 6] As a pigment, fine clay (MIRASHEEN manufactured by Engelhard, volume distribution particle size 0.40 to 0.40)
Pigment consisting of 80 parts of 4.20 μm: 60.2%) and 20 parts of fine ground heavy calcium carbonate (FMT-90 manufactured by Phimatech, volume distribution particle size 0.40 to 4.20 μm: 71.9%) (volume: Distribution particle size 0.40 to 4.20 μm: 6
Example 2 except that 0.2 part of sodium polyacrylate as a dispersant as a dispersant was added to 2.5%) and dispersed with a serie mixer to prepare a pigment slurry having a solid content concentration of 70%. A coated paper was obtained in the same manner as in. [Comparative Example 7] As a pigment, secondary clay (DB coat manufactured by Dry Ranch Kaolin Co., volume distribution particle size 0.40 to 0.40)
Pigment (volume: 4.20 μm: 57.6%) 60 parts, fine grained heavy calcium carbonate (FMT-90 manufactured by Phimatech, volume distribution particle size 0.40 to 4.20 μm: 71.9%) 40 parts Distribution particle size 0.40 to 4.20 μm: 6
Example 3 except that 0.2 part of sodium polyacrylate as a dispersant was added to 3.3%) and dispersed with a serie mixer to prepare a pigment slurry having a solid content concentration of 70%. A coated paper was obtained in the same manner as in. [Comparative Example 8] As a pigment, 25 parts of delaminated clay (DB plate manufactured by Dry Ranch Kaolin, volume distribution particle size 0.40 to 4.20 µm: 48.1%), second grade clay (manufactured by Dry Ranch Kaolin) DB coat, volume distribution particle size 0.40 to 4.20 μm: 57.6%) 25
25 parts, fine clay (AMAZON manufactured by Kadam, volume distribution particle size 0.40 to 4.20 μm: 53.8%) 25 parts, fine ground calcium carbonate (FMT-manufactured by Pharmatec)
90, volume distribution particle size 0.40 to 4.20 μm: 71.9
%) 25 parts pigment (volume distribution particle size 0.40-4.
20 μm: 57.9%) was added with 0.2 part of sodium polyacrylate as a dispersant as a dispersant and dispersed with a serie mixer to prepare a pigment slurry having a solid content concentration of 70%. A coated paper was obtained in the same manner as in Example 1. [Comparative Example 9] A commercially available light-weight coated paper “Super Pyrene Dx” having a basis weight of 60.2 g / m ² was used for comparison. [Comparative Example 10] A commercially available fine coated paper “Pyrene Dx” manufactured by Nippon Paper Industries having a basis weight of 60.2 g / m ² was used for comparison.

The above effects are shown in Table 1.

[0022]

[Table 1]

[0023]

With the constitution of the present invention, it is possible to efficiently obtain a matte coated paper having a low density and an excellent printing gloss.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideki Hayasaka 1 505, Pulp Town, Asahikawa City, Hokkaido Inside Asahikawa Mill of Nippon Paper Industries Co., Ltd. (56) Reference JP-A-3-152297 (JP, A) JP-A-4-152297 370298 (JP, A) JP 6-10298 (JP, A) JP 10-226982 (JP, A) JP 59-199897 (JP, A) JP 6-65896 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) D21H 11/00-27/42

Claims (2)

(57) [Claims] 1. Pigment particles in an amount of 0.4 to 4 on a volume basis on a base paper containing mechanical pulp as a pulp for papermaking in an amount of 10% by weight or more and amorphous silica as a filler in an amount of 3 to 12% by weight. A coated paper provided with a coating layer of a pigment having a particle size distribution of 65% or more in the range of 2 μm,
Matte coated paper obtained by treating this coated paper with a soft nip calender having a rigid roll temperature of 150 ° C. or higher. 2. The bulk specific gravity of the amorphous silicate is 0.2 to.
The matte coated paper according to claim 1, which is 0.8 g / ml.