JP6793909B2 - Manufacturing method of coated printing paper and coated printing paper - Google Patents

Description

The present invention relates to a method for producing a coated printing paper having a high glossiness on one side and a high strength, and a coated printing paper.

Since general coated printing paper is printed on both sides, similar coating layers are formed on both sides of the base paper, and the glossiness and smoothness quality are manufactured to be the same on the front and back sides of the paper. ing. In some applications, only one side is used. For example, if it is printed on the front surface and it does not matter if the back surface looks different from the front surface, eliminating the coating on the back surface is advantageous for the strength of the paper at the same basis weight. This is because the strength of the paper depends mainly on the pulp, and this tendency is more remarkable in the coated printing paper having a lower basis weight.

When a coating layer is provided on one side of the base paper, the smoothness of the back surface is low when finishing the calendar, so the calendar effect is low, and even if the calendar conditions (temperature, nip pressure) are strict, the coated surface has a uniform and high glossiness. There was a problem that it could not be obtained.

In addition, since paper for wrapping needs to have a role of wrapping and holding goods, not only print quality but also quality such as strength and rigidity is one of the important factors. As a method for achieving both print quality and strength, for example, the base paper contains an amphoteric polyacrylamide-based paper strength agent and a polyamide epichlorohydrin-based paper strength agent, and a pigment layer is formed on one side of the base paper to have wet strength. A coated paper having a degree of 500 seconds or more and a glossiness of 50% or more is disclosed. (Patent Document 1)

It is disclosed that the difference in fiber orientation angles between the front and back surfaces and the fiber orientation ratio are adjusted to a certain range at the time of papermaking, and a coating layer of 1 to 10 g / m ² is provided on at least one surface. (Patent Document 2)

Further, 1 to 10 g / 10 g / 10 g / coating layer containing a pigment and an adhesive on at least one side of the base paper formed by using 50% by weight or more of softwood kraft pulp and having a longitudinal-horizontal tensile strength ratio adjusted to 1.7 or more. m ² A coated wrapping paper having a formed basis weight in the range of 100 to 500 g / m ² is disclosed. (Patent Document 3)

However, in the technique of Cited Document 1, the cost increases due to the addition of chemicals. The technique of Cited Document 2 has a limit in increasing the strength. Since the technique of Cited Document 3 uses 50% by weight or more of softwood kraft pulp, the texture of the paper becomes poor, it is difficult to apply a uniform paint, and high glossiness cannot be obtained.

Therefore, even with these techniques, a coated printing paper that is satisfactory in high glossiness and strength has not yet been obtained. In particular, low-basis coating printing paper requires a small amount of coating, so it is difficult to achieve both glossiness and strength.

Japanese Unexamined Patent Publication No. 2005-248394 Japanese Unexamined Patent Publication No. 2006-83487 Japanese Unexamined Patent Publication No. 2006-97149

An object of the present invention is to provide a method for producing a coated printing paper having high glossiness on one side and having high strength in spite of being lightweight, and a coated printing paper.

As a result of diligent studies on a method for producing a coated printing paper produced by applying a paint, the present inventor has found that the above problems can be solved by the means described below.

The invention according to claim 1 is a base paper containing 5 to 50% by mass of coniferous kraft pulp in the total pulp in a method for producing a coated printing paper obtained by coating a base paper with a paint mainly composed of a pigment and an adhesive. In addition, the paint is applied to both sides of the base paper by the film transfer method, and after drying, the paint is applied to one side by the blade coater and dried, and the blade coater coated surface is hot-rolled by the soft nip calendar consisting of hot roll and soft roll. It is a method for manufacturing a coated printing paper, characterized in that at least two nip treatments are performed so as to be in contact with the paper.

The invention according to claim 2 is the method for manufacturing a coated printing paper according to claim 1, wherein water coating is performed on a surface opposite to the blade coater coated surface.

According to the method for producing a coated printing paper of the present invention, it is possible to provide a coated printing paper having a low basis weight, high strength, and excellent glossiness.

Hereinafter, embodiments of the present invention will be described.
A paper machine composed of wire parts, press parts, dryer parts, and reel parts is used to manufacture the coated printing paper of the present invention. The model of the paper machine is not particularly limited, and a long net paper machine, a twin wire paper machine, etc. can be used as appropriate, but an on-top type or a gap former type twin wire paper machine is desirable because the difference between the front and back sides is small.

In the coated printing paper of the present invention, kraft pulp, used paper pulp, machine pulp and the like can be used as raw material pulp. As the kraft pulp, softwood bleached kraft pulp (NBKP), hardwood bleached kraft pulp (LBKP) and the like can be used. Further, as the used paper pulp, used paper deinked pulp (DIP) such as newspaper used paper deinked pulp and high-quality used paper deinked pulp can be used. As the mechanical pulp, stone ground pulp (SGP), pressurized stone ground pulp (PGP), refiner ground pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP) and the like can be used.

The coated printing paper of the present invention contains 5 to 50% by mass of NBKP in the total pulp.
By doing so, it is possible to give strength to the base paper even with a low basis weight, so that it is possible to reduce the possibility of paper breakage by the coater or the printing machine. If it exceeds 50% by mass, uneven texture and uneven coating are likely to occur, and the glossiness may be insufficient or uneven gloss may occur. The content of NBKP can be determined by separating the paper by the JIS P8120: 1998 paper, paperboard and pulp fiber composition test method.
The Canadian standard filtrate (CSF) of NBKP to be blended is preferably adjusted to 400-600 ml. If the freeness is lower than 400 ml, paper breakage at the coater is likely to occur due to insufficient tear strength, and if it is higher than 600 ml, coating unevenness due to uneven texture is likely to occur, and the glossiness is insufficient, resulting in poor printability. ..
For the coated printing paper of the present invention, it is desirable to use used paper pulp for effective use of resources, and it is better that the blending ratio is high. However, since used paper pulp has lower whiteness and strength than bleached kraft pulp, 10 It is desirable to set it to ~ 50% by mass.

A filler may be added to the coated printing paper of the present invention for the purpose of improving ink color development, ink inking property, opacity, and whiteness. The type of filler is not particularly limited, and fillers generally used for coated printing paper can be used. Specifically, inorganic fillers such as calcium carbonate, titanium dioxide, talc, clay, white carbon, and silica, plastic pigments, and the like can be used. Of these, it is preferable to use calcium carbonate, which has a high degree of whiteness and is easily available. The amount of the filler added is not particularly limited, but if the amount of the filler added is excessive, the strength of the paper is lowered, so it is desirable to determine the amount of the filler added in consideration of the tensile strength.

In the coated printing paper of the present invention, a sulfuric acid band, a sizing agent, a bulk improver, a paper strength enhancer and the like can be added to the raw material pulp. As the sizing agent, a rosin-based sizing agent, an alkyl ketene dimer, an alkenyl succinic anhydride or the like can be used. As the paper strength enhancer, cationized starch, polyacrylamide resin, etc. can be used, but the coated printing paper of the present invention has a tensile strength (length) of 2.2 kN / m or more and an elongation (length) of 1.2. It is desirable that it is% or more. If the tensile strength (vertical) is less than 2.2 kN / m or the elongation (vertical) is less than 1.2%, it is easily broken.

In the coated printing paper of the present invention, cationized starch may be added to the base paper. The addition rate is preferably 0.2 to 1.0% with respect to the raw material pulp. By adding the cationized starch, the tensile strength and elongation are improved, and it is possible to prevent paper breakage in the coater and paper breakage in the printing machine. If the amount of cationized starch added is less than 0.2%, the effect of addition is low, and if it is more than 1.0%, the effect is leveled off, the texture becomes poor, and water extraction is poor due to felt stains on the paper machine. May cause trouble. The degree of substitution of the cationized starch used is preferably 0.02 to 0.05, which is advantageous for improving paper strength. The degree of substitution is defined by the ratio of the number of hydroxyl groups substituted by ether bonds to the number of glucose units in the starch molecule.
The cationized starch used is preferably a cationized starch produced from starch having an amylose content of 20% or less because it has excellent aging resistance.

In addition, if necessary, additives such as a wet paper strength enhancer, a slime control agent, a pitch control agent, an antifoaming agent, and a dye can also be used.

In the coated printing paper of the present invention, a paint containing pigments and adhesives as main components is applied to the surface of the base paper. The pigment used is not particularly limited, but calcium carbonate, talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicate, colloidal silica, and satin, which are conventionally used for coated paper, are used. If necessary, one or more kinds of inorganic pigments such as white can be mixed and used.

In the present invention, an adhesive is blended with the pigment in the paint in order to improve the adhesive ability of the pigment and avoid troubles related to surface strength such as pilling.
The adhesives used are various types such as styrene / butadiene type, styrene / acrylic type, ethylene / vinyl acetate type, butadiene / methyl methacrylate type, vinyl acetate / butyl acrylate type, etc., which have been conventionally used for coated paper. Polymers and polyvinyl alcohol, maleic anhydride copolymers, synthetic adhesives such as acrylic acid / methylmethacrylate copolymers, casein, soybean protein, synthetic protein proteins, oxidized starch, positive starch, urea phosphate esterification Use by appropriately selecting one or more types of ordinary coating paper adhesives such as starch, etherified starch such as hydroxyethyl etherified starch, starches such as dextrin, and cellulose derivatives such as carboxyethyl cellulose, hydroxyethyl cellulose, and hydroxymethyl cellulose. can do.

The coated printing paper of the present invention is coated on both sides of a base paper by a film transfer method, dried, and then coated on one side by a blade coater and dried. In the blade coating method, since the paint is scraped off by the blade, it is possible to coat the paint with a uniform thickness, the printability is good, and the adjustment range of the coating amount is wide, which is also advantageous.

In the coated printing paper of the present invention, it is desirable that water is applied to the surface opposite to the surface to which the paint is applied by the blade coater, and in this way, the curl adjustment of the coated printing paper becomes easy. The water may be applied before or after the process of applying the paint by the blade coater.

When the paint is applied to both sides of the base paper by the film transfer method, the amount of paint applied is preferably ³ to 8 g / m ² per side. The purpose of coating is to reduce the unevenness of the base paper and increase the glossiness of the coated printing paper, but if it is less than 3 g / m ² , this effect is insufficient, and if it is more than 8 g / m ² , the basis weight of the base paper is low. That is, the amount of pulp is reduced, so that the strength of the coated printing paper is reduced.

When the paint is applied to one side by the blade coater, the amount of the paint applied is preferably ³ to 8 g / m ² . If the coating amount is less than 3 g / m ^2, printability deteriorates due to insufficient glossiness and uneven gloss. If it is more than 8 g / m ^2, the basis weight of the base paper will be low. That is, since the amount of pulp is reduced, the strength of the coated printing paper is reduced.

As a method of drying the wet coating layer after coating the paint, various methods such as steam drying, gas heater drying, electric heater drying, and infrared heater drying can be adopted.

In the production of the coated printing paper of the present invention, after drying with a dryer, smoothing is performed with a calendar device. As the calendar device, a soft nip calendar composed of a hot roll and a soft roll is used. The number of nip, nip pressure, roll temperature, roll material, roll hardness, etc. can be set according to the required smoothness and glossiness, but in the coating printing paper of the present invention, the blade coater coated surface is hot. It is characterized in that at least two nip processes are performed so as to be in contact with the roll. By doing so, it is possible to obtain a chewy paper quality while maintaining a high glossiness on one side.

The coated printing paper of the present invention has a basis weight (JIS P8124) of 40 to 100 g / m ² . If the basis weight is less than 40 g / m ² , that is, if the basis weight of the base paper is about 30 g / m ² or less, coating with a blade coater becomes difficult. The larger the basis weight, the more advantageous the strength, but from the viewpoint of resource saving, 100 g / m ² or less is preferable, 80 g / m ² or less is more preferable, and 70 g / m ² or less is further preferable.

The coated printing paper of the present invention has higher strength against basis weight than the coated printing paper having the same degree of glossiness. Specifically, the tensile strength length (kN / m) ÷ basis weight (g / m ² ) can be about 0.060 to 0.080, preferably about 0.065 to 0.085. That is, it has high glossiness and high strength even with a low basis weight. Therefore, it can be applied to high-definition printing and can be used for applications requiring high strength.

Since the coated printing paper of the present invention is coated with the paint twice on one side, the glossiness and whiteness can be increased. The glossiness (JISP8142) of the obtained coated printing paper is preferably 40% or more, more preferably 50% or more, and further preferably 55% or more. The whiteness (JIS P8148) is preferably 75% or more, more preferably 80% or more, and further preferably 85% or more. The opacity (JIS P8149) is preferably 75% or more, more preferably 80% or more, and further preferably 85% or more. If the whiteness is lower than 75%, the print quality is inferior, and if the opacity is lower than 75%, strike-through is noticeable.

It is also possible to perform smoothing with a calendar in the pre-process of applying paint with a blade coater. In this case, if the smoothness after the smoothing treatment is too high, the density of the paper becomes high, so that the penetration of the paint is poor and the coating amount becomes uneven, which causes wrinkles and fluttering during printing. If the smoothness is too low, uneven coating tends to occur. The smoothness after the smoothing treatment is preferably 15 to 100 seconds.
As described above, the coated printing paper of the present invention can be obtained.

Hereinafter, the effects of the present invention will be specifically represented by Examples and Comparative Examples. Unless otherwise specified,% represents mass%, and the amount added is represented by the solid content or the active ingredient with respect to the absolute dry pulp.

(Example 1)
A pulp dispersion consisting of 35 parts by mass of NBKP (510 ml CSF), 35 parts by mass of LBKP (220 ml CSF), and 30 parts by mass of high-quality waste paper deinked pulp (160 ml CSF), with 1.6% sulfuric acid band (as is) and cationized starch (GS). -Manufactured by L Japan Co., Ltd. Product name: Geltron 24) 1.0% was added to make paper.

Next, the paint was applied to both sides of the base paper as shown below by a film transfer method using a rod metering size press.
Heavy calcium carbonate (product name Hydrocurve 90HS, manufactured by Bihoku Powder Industry Co., Ltd.) 90 parts by mass, flat kaolin (product name Kao White S, manufactured by Shiraishi Calcium Co., Ltd.) 3 parts by mass, fine kaolin (product name Kaofine, Shiraishi Calcium Co., Ltd.) 7 parts by mass, SBR latex (product name: Smartex PA8008, Nippon A & L Inc.) 2.5 parts by mass,
Urea Phosphate Esterified Starch (Product Name Starcoat 16 manufactured by Nippon Foods Chemicals Co., Ltd.) 9.0 parts by mass Dispersant (Product Name Aron T50 manufactured by Toa Synthetic Co., Ltd.) 15 parts by mass (against kaolin)
Fluorescent dye (Product name: Kayahole STCL Nippon Kayaku Co., Ltd.) 0.4 parts by mass Coating amount 4.5g / m ² per side (front and back same coating amount)

Next, water was applied to the F surface of the base paper using a short duel type blade coater.

Next, using a short duel type blade coater, a paint containing a pigment and an adhesive was applied to the W surface of the base paper as described below.
Fine-grained heavy calcium carbonate (product name: Seta Curve HG, manufactured by Bihoku Powder Industry Co., Ltd.) 30 parts by mass, flat kaolin (product name: Khao White S, manufactured by Shiraishi Calcium Co., Ltd.) Calcium Co., Ltd.) 52 parts by mass SBR latex (Product name: Smartex PA8008, manufactured by Nippon A & L Inc.) 9.0 parts by mass Urea phosphate esterified starch (Product name: Starcoat 16 manufactured by Nippon A & L Inc.) 4.0 parts by mass Powder (Product name Aron T50 manufactured by Toa Synthetic Co., Ltd.) 15 parts by mass (against kaolin)
Fluorescent dye (Product name: Kayahole STCL, manufactured by Nippon Kayaku Co., Ltd.) 0.4 parts by mass Coating amount 5.0 g / m ²

After coating, it was dried and subjected to 2-nip treatment (linear pressure 250 kN / m temperature 180 ° C., linear pressure 190 kN / m temperature 150 ° C.) using a soft calendar consisting of a hot roll and a soft roll. In each of the two nip treatments on the soft calendar, the blade coater coated surface was treated so as to be in contact with the hot roll.
In this way, a coated printing paper having a basis weight of 71.1 g / m ² was obtained.

(Example 2)
A coated printing paper was obtained in the same manner as in Example 1 except that the basis weight was 50.7 g / m ² .

(Example 3)
A coated printing paper was obtained in the same manner as in Example 1 except that the pulp composition was 5 parts by mass (510 ml CSF) of NBKP, 65 parts by mass (220 ml CSF) of LBKP, and 30 parts by mass (160 ml CSF) of high-quality waste paper deinked pulp.

(Example 4)
Coated printing paper was obtained in the same manner as in Example 1 except that the pulp composition was NBKP 40 parts by mass (510 ml CSF), LBKP 30 parts by mass (220 ml CSF), and high-quality waste paper deinked pulp 30 parts by mass (160 ml CSF).

(Comparative Example 1)
The coating printing paper was used in the same manner as in Example 1, except that the topcoat paint was applied to both sides of the base paper without water coating, and the base paper basis weight was adjusted with the target basis weight of 70 g / m ^2. Obtained.

(Comparative Example 2)
A coated printing paper was obtained in the same manner as in Example 2 except that the pulp composition was 65 parts by mass (220 ml CSF) of LBKP and 35 parts by mass (160 ml CSF) of high-quality waste paper deinked pulp.

(Comparative Example 3)
A coated printing paper was obtained in the same manner as in Example 1 except that the pulp composition was NBKP 50 parts by mass (510 ml CSF), LBKP 20 parts by mass (220 ml CSF), and high-quality waste paper deinked pulp 30 parts by mass (160 ml CSF).

(Comparative Example 4)
A coated printing paper was obtained in the same manner as in Example 1 except that the treatment with the soft calendar was a one-nip treatment (line pressure 250 kN / m temperature 180 ° C.).

(Comparative Example 5)
A coated printing paper was obtained in the same manner as in Comparative Example 1 except that the coating was not performed by the rod metering size press.
Table 1 shows the evaluation results of the coated printing papers obtained in the above Examples and Comparative Examples.

The test method and evaluation method are as follows.
(Basis weight) JISP8124: 1998 Paper and paperboard-Basis weight measurement method (NBKP content) For high-quality waste paper deinked pulp, the fiber composition (based on JISP8120: 1998 paper, paperboard and pulp-fiber composition test method) was obtained. It was calculated from the pulp content.
(Glossiness) JISP8142: 2005 Paper and Paperboard-75 Degree Mirror Gloss Measurement Method (Smoothness) JISP8119: 1998 Paper and Paperboard-Smoothness Test Method by Beck Smoothness Tester (Tensile Strength) JISP8113: 2006 Paper and Test method of paperboard-tensile characteristics (evaluation of stamp surface) Solid printing was performed with offset ink using an RI printability tester, and the glossiness of the stamp surface was relatively evaluated in the following three stages.
◎ Excellent ○ Good × Insufficient gloss or uneven gloss

As shown in Table 1, in Examples 1 to 6 of the present invention, the glossiness is high, the strength against the basis weight is high, and the stamp surface evaluation is also good. In Comparative Example 1, since the coating amount is the same on both sides, the strength with respect to the basis weight is low. In Comparative Example 2, since the content of NBKP is low, the strength with respect to the basis weight is low. In Comparative Example 3, since the content of NBKP is high, the stamp surface evaluation is poor. In Comparative Example 4, since the calendar 1 nip processing is performed, the glossiness is low and the stamp surface evaluation is poor. Since Comparative Example 5 is a single coating, the glossiness is low and the stamp surface evaluation is poor.

The coated printing paper of the present invention can be used for packaging and the like, and can be particularly used for applications where only one side is used.

Claims (2)

In a method for producing coated printing paper in which a base paper is coated with a paint mainly composed of pigments and adhesives, the base paper contains 5 to 50% by mass of coniferous kraft pulp in the total pulp by a film transfer method. paint coated on both surfaces of, after drying, by a blade coater, the coating material on one surface coating, and dried by soft nip calender comprising a hot roll and a soft roll, at least 2 nip as a blade coater coating surface is in contact with the hot roll A method for producing coated printing paper, which comprises the above-mentioned processing. The method for producing a coated printing paper according to claim 1, wherein water coating is performed on a surface opposite to the blade coater coated surface.