JP5064953B2 - Bulky medium printing paper - Google Patents

Description

  The present invention relates to a bulky medium-sized printing paper that has low density and flexibility (low rigidity), and has excellent printability and suppresses ink bleeding.

  One of the important qualities demanded for paper products in recent years is bulkiness (low density). Along with the recent increase in environmental protection, users have been able to reduce the weight of paper while maintaining the thickness of paper and effectively reduce the density of paper. It has been demanded.

  Conventionally, as one method for reducing the density (bulking) of paper, there is the use of bulky pulp. Wood pulp is generally used as a pulp for papermaking. However, compared with chemical pulp extracted from lignin, which is a reinforcing material in wood fibers, using chemicals, the wood is refined using ground pulp or refiner that grinds the wood with a grinder. It is known that mechanical fibers such as refiner mechanical pulp, thermomechanical pulp, and the like have more rigid fibers and are effective in reducing the density of paper. However, paper made by blending mechanical pulp has high rigidity, so there is a problem that the printed and bound books are not easily turned. Improvement was an issue.

  It is also known to use a bulking agent as another method for reducing the density of paper. Known bulking agents include, for example, paper bulking agents containing a specific alcohol and / or polyoxyalkylene adduct thereof (see Patent Document 1), nonionic surfactants (see Patent Document 2), polyhydric alcohols and the like. Paper bulking agents comprising fatty acid ester compounds (see Patent Document 3) are known, and a technique in which these paper bulking agents are applied to paperboard is also disclosed (see Patent Document 4).

  Among these, as a non-surfactant bulking agent, a paper bulking agent containing at least one compound selected from a cationic compound having a specific structure, an amine, an acid salt of an amine and an amphoteric compound is disclosed. (See Patent Document 5). There are also fatty acid polyamide polyamine type bulking agents. Further, a compound having a water separation degree of 4% or more and a compound having an effect of improving paper quality of any two of bulk, whiteness, and opacity is described (see Patent Document 6). Furthermore, a pulp sheet manufacturing method using a compound having a water separation degree of 4% or more and having a paper quality improving effect of any one of bulk, whiteness and opacity is disclosed (patent) Reference 7).

  However, even if a low-density paper is obtained, the characteristics of only the low-density paper are so-called ink bleed (hereinafter referred to as “the ink bleed”). "Bleed") occurs, which contributes to printing troubles and is a major problem associated with the reduction in paper density. In recent years, ink that is more likely to bleed may be used, and bleed occurs even on paper that has not been problematic until now.

International Publication No. 98/03730 Pamphlet JP-A-11-200263 Japanese Patent No. 2971447 Japanese Patent No. 3041294 JP-A-11-269799 Japanese Patent No. 3283248 JP 2003-105685 A

  In view of the above background, it is an object of the present invention to provide a bulky medium-sized printing paper that has low density, flexibility (low rigidity), excellent printability, and no bleeding (print bleeding).

In order to solve the above problems, the bulky medium-sized printing paper of the invention according to claim 1 is a bulky medium-sized printing paper in which a surface treatment agent is applied on a base paper containing a bulking agent,
The base paper contains 30% by weight or more of mechanical pulp per pulp weight, and an unsaturated fatty acid amide bulking agent is contained as the bulking agent, and the content is 0.1 to 2.0% based on the total dry weight of the pulp. And at least a cationic surface sizing agent is applied as the surface treatment agent, and the coating amount of the surface treatment agent is 0.3 to 3.0 g / m ² per one side of the paper , an upper Symbol cationic surface sizing agent is 5-10 wt%, and the coating amount of the cationic surface sizing agent is characterized in that it is a 0.05 to 1.0 g / ^{m 2} per paper face.
The bulky medium-sized printing paper of the invention according to claim 2 is coated with the cationic surface sizing agent and modified starch as the surface treatment agent.

  According to the present invention, it is possible to obtain a bulky medium-size printing paper that can suppress the ink bleeding phenomenon even at low density, and is flexible and excellent in printability.

  In the medium-quality printing paper of the present invention, chemical pulp (such as bleached kraft pulp (NBKP) or unbleached kraft pulp (NUKP), bleached kraft pulp (LBKP) or unbleached kraft pulp (LUKP) of hardwood) as raw material pulp , Softwood, hardwood mechanical pulp (groundwood pulp (GP), refiner mechanical pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), etc.) or deinked pulp (DIP) alone or in any It can be used by mixing at a ratio. In the present invention, the mechanical pulp is 30% by weight or more per pulp weight, and has a softness effect while being bulky.

  The bulking agent used in the present invention is an unsaturated fatty acid amide system. In the case of making medium paper containing mechanical pulp, unsaturated fatty acid amide bulking agents are compared with other bulking agents such as saturated fatty acid amides, fatty acid esters, higher alcohol alkylene oxides, amines, etc. High bulky effect.

  Examples of the unsaturated fatty acid amide bulking agent include oleic acid amide amines, linoleic acid amide amines, oleic acid amide imidazolines, linoleic acid amide imidazolines.

  The amount of the bulking agent added to the total pulp is preferably 0.1 to 2.0%, more preferably 0.1 to 1.2%, and more preferably 0.5 to 1.2, based on the total dry weight of the pulp. % Is more preferable. If it is less than 0.1%, there is almost no bulky effect, and even if added over 2.0%, the bulk does not increase any more.

  The bulky medium-size printing paper of the present invention may contain a filler. As the filler, known fillers such as white carbon, talc, kaolin, clay, heavy calcium carbonate, light calcium carbonate, titanium oxide, or synthetic resin filler can be used. The filler content is preferably 3 to 20% by weight per paper weight.

Further, the bulky medium-sized printing paper of the present invention is used for papermaking such as sulfate bands, various anionic, cationic, nonionic or amphoteric yield improvers, drainage improvers, paper strength enhancers, and internal sizing agents. An internal additive can be used as required.
Furthermore, there is no problem even if a dye, a fluorescent brightening agent, a pH adjuster, an antifoaming agent, a pitch control agent, a slime control agent, or the like is added as necessary.

  Paper making of the bulky medium-sized printing paper of the present invention can be performed by a known paper machine such as a long paper machine, a gap former, or a hybrid former (on-top former). From the viewpoint of bulkiness of medium quality paper, it is desirable that the press linear pressure in the paper machine is as low as possible within the range that does not hinder the operation, and the calendar linear pressure is impaired in smoothness of bulky medium quality printing paper. As low as possible within the range. In addition, it is necessary to apply a surface treatment agent during papermaking.

In the present invention, an unsaturated fatty acid amide system is used as a bulking agent, and a cationic surface sizing agent is used as a surface treatment agent. The unsaturated fatty acid amide bulking agent is excellent in the effect of making the medium paper bulky and flexible, but tends to cause bleeding, and the starch-based surface paper strength agent is 0.3 to 3.0 g. / M ² , preferably 0.5 to 2.0 g / m ^2, to prevent this, but in recent years, the above measures have become insufficient due to the use of ink that tends to bleed. The occurrence of bleeding can be suppressed by applying the surface treatment agent of the cationic surface sizing agent. In order to suppress the occurrence of this bleed, the coating amount of the cationic surface sizing agent is preferably 0.05 to 1.0 g / m ² per side with respect to the paper made.

  The cationic surface sizing agent of the present invention may be a copolymer of a hydrophobic monomer and a hydrophilic monomer having a cationic functional group. Specifically, the cationic surface sizing agent is a styrenic, styrene acrylate, or acrylate cationic. It is a sizing agent. Hydrophobic monomers include styrene and acrylic acid esters, and hydrophilic monomers include dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylaminoethyl (meth) acrylate, diethylaminopropyl (meth) acrylate, and the like. Can be mentioned.

In the present invention, a cationic surface sizing agent is necessary so as not to generate bleed. For the purpose of improving surface strength and size, for example, raw starch, oxidized starch, esterified starch, cationized starch, enzyme Modified starch such as modified starch, aldehyde-modified starch, hydroxyethylated starch, cellulose derivatives such as carboxymethylcellulose, hydroxyethylcellulose, methylcellulose, modified alcohols such as polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, styrene-butadiene copolymer, polyvinyl acetate, One or more kinds of vinyl chloride-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, polyacrylic acid ester, polyacrylamide and the like can be used in combination. Among them, in order to improve the surface strength and size, it is preferable to apply a modified starch in combination, and the application of hydroxyethylated starch is most preferable. In order to balance the surface strength and the bleed suppressing effect, the coating amount of the surface treatment agent is preferably 0.3 to 3.0 g / m ² per side, more preferably 0. 5 to 2.0 g / m ² . Moreover, 1 to 10 weight% of saturated fatty acid polyamide polyamine epichlorohydrin polycondensate is preferable in a surface treating agent.

The kind of apparatus which apply | coats a surface treating agent does not have limitation in particular, It can apply | coat with coating machines, such as a 2 roll size press coater, a gate roll coater, a blade metalling coater, or a rod metalling coater. Other papermaking conditions are not particularly defined, and the pH during papermaking may be acidic, neutral or alkaline.
Further, for the purpose of smoothing the surface of the paper, the processing may be performed using a known calendar device such as a machine calendar, a soft nip calender, or a high temperature soft nip calender.

As described above, in the present invention, a cationic surface sizing agent is applied to paper obtained by making a paper stock to which an unsaturated fatty acid amide-based bulking agent is added, thereby providing low density and flexibility (low rigidity). In addition, it is possible to produce a bulky medium-sized printing paper that is excellent in printability and does not generate bleed.
The bulky medium-size printing paper of the present invention can be suitably used as book paper, offset printing paper or letterpress printing paper, gravure printing paper, and their coating base paper.

Examples are shown below, but these examples do not limit the scope of the present invention.
In the description, “%” is solid content weight%.
The tested mechanical pulp, bulking agent and surface paper strength agent are shown below.
The paper quality measurement method is as follows.
(1) Sample bulking agent / bulking agent A: oleic acid amidoamine-based bulking agent B: oleic acid amidoimidazoline-based / bulky bulking agent C: stearic acid amidoamine-based / bulky bulking agent D: stearic acid ester-based bulking agent E: lauryl Alcohol ether

(2) Paper quality measuring method / basis weight: Measured according to JIS P 8124.
-Paper thickness and density: Measured according to JIS P 8118.
・ Bleed test: Roland R202 printing machine, dampening solution with 1% added etchant (Tokyo Ink (manufactured), H liquid No. 8, used in Dai Nippon Printing), ink used with Inktec (manufactured) ) Was added using 10% compound added to indigo, and was stored in the dark for 30 days, and the degree of suppression of bleeding (bleed) on the back surface of the ink was visually evaluated.
The visual evaluation was performed in the following four stages.
A: Very good.
○: Good.
Δ: Slightly poor
X: Defect.

-Flexibility test (rigidity): Using a bending tester (Lorentzen & Wettre), the stiffness in the MD direction was measured, and the value obtained by the following calculation formula was taken as the stiffness in order to avoid the influence of the paper thickness.
Stiffness = 10 ⁵ x Bending tester stiffness measurement / (paper thickness) ³
Here, the unit of the measured value of pure bending stiffness is μN · m ² / m, and the unit of paper thickness is μm.
[Example 1]
To a pulp slurry of conifer TMP (CSF 110 ml), 1.5% sulfuric acid band and 1.0% bulking agent A are added, 3.0% calcium carbonate, 200 ppm yield agent (DR-3600, manufactured by Hymo Co., Ltd.), Paper is made with a Velve IV paper machine at a speed of 1000 m / min, and the weight ratio of the styrene cationic sizing agent, which is a copolymer of hydroxyethylated starch, styrene and dimethylaminoethyl methacrylate, is 20/1. The press liquid was applied at a coating amount of ² g / m ² with a gate roll coater and subjected to a nip pressure calendar treatment of 10 kgf to obtain a bulky medium-sized printing paper.

[Example 2]
The cationic sizing agent of Example 1 is a styrene acrylate cationic sizing agent which is a copolymer of styrene, 2-ethylhexyl methacrylate and dimethylaminoethyl methacrylate instead of the copolymer of styrene and dimethylaminoethyl methacrylate. Except that, a bulky medium-sized printing paper was obtained in the same manner as in Example 1.
[Example 3]
The cationic sizing agent in which the cationic sizing agent of Example 1 is a copolymer of n-butyl methacrylate, lauryl methacrylate, and dimethylaminoethyl methacrylate is used instead of the copolymer of styrene and dimethylaminoethyl methacrylate. Except that, a bulky medium-sized printing paper was obtained in the same manner as in Example 1.
[Example 4]
A bulky medium-sized printing paper was obtained in the same manner as in Example 1 except that the bulking agent B was used in place of the bulking agent A of Example 1.

[Example 5]
Bulky and medium-quality printing in the same manner as in Example 1 except that the weight blending ratio of the cationic sizing agent which is a copolymer of hydroxyethylated starch, styrene and dimethylaminoethyl methacrylate was changed to 10/1. Got the paper.
[Example 6]
In Example 1, bulky as in Example 1, except that the weight blending ratio of the cationic sizing agent, which is a copolymer of hydroxyethylated starch, styrene, and dimethylaminoethyl methacrylate, was 20 / 0.1. Quality printing paper was obtained.
[Comparative Example 1]
A bulky medium-quality printing paper was obtained in the same manner as in Example 1 except that the bulking agent C was used instead of the bulking agent A of Example 1.
[Comparative Example 2]
A bulky medium-sized printing paper was obtained in the same manner as in Example 1 except that the bulking agent D was used in place of the bulking agent A of Example 1.

[Comparative Example 3]
A bulky medium-sized printing paper was obtained in the same manner as in Example 1 except that the bulking agent E was used in place of the bulking agent A of Example 1.
[Comparative Example 4]
A bulky medium-sized printing paper was obtained in the same manner as in Example 1 except that an anionic sizing agent, which is a copolymer of styrene and acrylic acid, was used instead of the cationic sizing agent of Example 1.
[Comparative Example 5]
A bulky medium printing paper was obtained in the same manner as in Example 1 except that only hydroxyethylated starch was applied.

Table 1 shows the conditions of Examples 1 to 6 and Comparative Examples 1 to 4, and the results of density, bleed test, and flexibility test (rigidity).

From the results shown in Table 1, the following can be understood.
Since the density of the base papers of Examples 1 to 6 and Comparative Examples 4 and 5 containing the bulking agents A and B is smaller than that of Comparative Examples 1 to 3 containing other types of bulking agents, the unsaturated fatty acid amide It can be seen that the bulking agent of the system can have a lower density than other types of bulking agents.
Further, the stiffness of the base papers of Examples 1 to 6 and Comparative Examples 4 and 5 containing the bulking agents A and B is smaller than that of Comparative Examples 1 to 3 containing other types of bulking agents. It can be seen that the fatty acid amide-based bulking agent can be made more flexible than other types of bulking agents.
The base papers of Examples 1 to 6 containing the bulking agents A and B are low density and flexible as described above, and the cationic surface sizing agent is applied to the surface, thereby suppressing ink bleeding. You can see that

Claims (2)

A bulky medium-sized printing paper in which a surface treatment agent is applied on a base paper containing a bulking agent,
The base paper contains 30% by weight or more of mechanical pulp per pulp weight , and an unsaturated fatty acid amide bulking agent is contained as the bulking agent, and the content is 0.1 to 2.0% based on the total dry weight of the pulp. And at least a cationic surface sizing agent is applied as the surface treatment agent, and the coating amount of the surface treatment agent is 0.3 to 3.0 g / m ² per one side of the paper , an upper Symbol cationic surface sizing agent is 5-10 wt%, and bulky coating amount of the cationic surface sizing agent is characterized in that it is a 0.05 to 1.0 g / ^{m 2} per paper face wood containing Printing paper.   The bulky medium-sized printing paper according to claim 1, wherein the cationic surface sizing agent and modified starch are applied in combination as the surface treatment agent.