JP5064857B2 - Bulky medium-sized book paper - Google Patents

Description

  The present invention relates to a bulky medium-sized book paper having a low density and extremely high whiteness, good print finish, and high production efficiency.

  Currently, one of the important qualities required for paper products 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, wood pulp is generally used as a pulp for papermaking, but compared to chemical pulp obtained by extracting lignin, which is a reinforcing material in wood fibers, with chemicals, wood pulp is used to grind the wood with a grinder or refiner. It is known that a mechanical pulp such as a refiner mechanical pulp or a thermomechanical pulp that refines the fiber has a more rigid fiber and is more effective in reducing the density of paper. That is, as one method for reducing the density (bulking) of paper, there is the use of bulky pulp.

  However, most of the current mechanical pulp is made from softwood with a high lignin content, and it is difficult to produce pulp with high whiteness. Then there were many problems. Among mechanical pulps, conifer thermomechanical pulp has a relatively long fiber length and high rigidity, so that paper made from this as a raw material for pulp has a poor texture, smoothness is reduced, or offset printing There was a problem that the ink inking was poor. Paper made from coniferous thermomechanical pulp has high rigidity, so that the foldability, which is one of the workability at the time of offset printing, is deteriorated, and the ease of turning over printed and bound books is poor. There was a problem.

Therefore, as a result of intensive studies to solve the above problems, the present applicant established and filed a technology for producing mechanical pulp having a characteristic of bulkiness, high whiteness, and high specific scattering coefficient from a specific hardwood. (Patent Document 1). In addition, the present applicant has already applied for a printing paper containing hardwood mechanical pulp having low density, high whiteness, high opacity, and excellent printability (Patent Document 2). Furthermore, the present applicant has also applied for printing paper containing hardwood mechanical pulp and a bulking agent (Patent Document 3). However, in these bulky technologies, when the density is 0.45 to 0.55 g / cm ³ , the limit is to obtain a sheet with a whiteness of about 65 to 75%.
In addition, in bulky paper, when clear coating such as a sizing agent is used, the amount of liquid absorption increases and the drying load increases, which causes a problem that the paper making speed decreases.
As described above, in order to obtain a high-quality printing paper that uses mechanical pulp and is bulky but has high whiteness and good print finish, the whiteness is improved and the bending stiffness of the printing paper is reduced. Therefore, improvement of so-called flexibility has been an issue. Further, when making bulky paper, it has been a problem to suppress a reduction in paper making speed.

JP 2003-27385 A JP 2003-49386 A JP 2005-163253 A

  In view of such a situation, the present invention provides a bulky medium-sized book paper that has a low density but a very high degree of whiteness and a good print finish, and further suppresses a decrease in papermaking speed. It is an object of the present invention to obtain a bulky medium-sized book paper that can be operated and has good operability.

As a result of diligent research to solve the above problems, the present inventors use bleached thermomechanical pulp and bleached kraft pulp with high bulking effect, and further use saturated aliphatic amide-based bulking agents. As a result, it has been found that a bulky medium-sized book paper having a very high whiteness, a good print finish, a reduction in paper making speed, and a good operability can be obtained while having a low density.
In addition, when bleached hardwood thermomechanical pulp is used as the bleached thermomechanical pulp, it has been found that higher quality plaster bulky medium book paper can be obtained, and the present invention has been completed.

The basic configuration of the bulky medium-sized book paper of the present invention is as follows.
(1) It contains bleached kraft pulp and bleached thermomechanical pulp, the composition weight ratio of bleached kraft pulp and bleached thermomechanical pulp is 60/40 to 90/10, and the pulp freeness is 250 to 350 mlCSF, A bulky medium-sized book paper containing a saturated fatty acid amide based bulking agent, having a density of 0.45 to 0.55 g / cm ³ and a whiteness of 77 to 83%.
(2) The bulky medium-sized book paper according to (1) above, wherein the bleached thermomechanical pulp is bleached hardwood thermomechanical pulp.

  To obtain a bulky medium-sized book paper that has low density but high whiteness and good print finish, and that can suppress a decrease in papermaking speed and has good operability. Can do.

In the bulky medium-sized book paper of the present invention, the pulp composition contains bleached kraft pulp and bleached thermomechanical pulp, and the compositional weight ratio is 60/40 to 90/10 parts / part, preferably 70/30 to 80/20. When the blending ratio of kraft pulp exceeds 90%, the density becomes high, and when the blending ratio of thermomechanical pulp exceeds 40%, paper breakage is likely to occur in the press and operation becomes difficult.
Kraft pulp may be blended with softwood bleached kraft pulp (NBKP) in order to increase paper strength. However, when the blending ratio of NBKP exceeds 20%, the formation and smoothness decrease.
The thermomechanical pulp used in the present invention has a high bulking effect as compared to groundwood pulp and refiner mechanical pulp, and hardwood is particularly preferable. The tree species is preferably Eucalyptus or Maple.
In addition, as the pulp used in the present invention, bleached kraft pulp and bleached thermomechanical pulp are used, but crushed wood pulp, refiner mechanical pulp, and deinked pulp can be used as long as the effects of the present invention are not impaired. . The blending ratio of bleached kraft pulp and bleached thermomechanical pulp is preferably 90% by weight or more based on the total pulp.

  The pulp containing bleached kraft pulp and bleached thermomechanical pulp used in the present invention has a freeness of the whole pulp in the range of 250 to 350 ml CSF. If it is less than 250 ml CSF, it is difficult to make it bulky, and if it exceeds 350 ml CSF, the amount of sizing liquid absorbed by the 2-roll size press increases, the paper making speed decreases, and the printing finish of the paper also deteriorates.

The bulking agent used in the present invention is a saturated aliphatic amide system.
Examples of the saturated aliphatic amide type used here include a saturated fatty acid monoamide type, a saturated fatty acid diamide type, and a saturated fatty acid polyamide type. When making paper with high blending of kraft pulp, saturated aliphatic amide-based bulking agents have a significantly higher bulking effect than bulking agents such as higher alcohol alkylene oxide adducts and polyhydric alcohol fatty acid esters.

  When coated with a two-roll size press coater, the saturated fatty acid amide-based bulking agent has a smaller amount of liquid absorption than the unsaturated fatty amide-based or higher alcohol alkylene oxide adduct-based bulking agent. Therefore, the drying load of the after dryer can be suppressed. When combined with an internally added sizing agent, the effect increases. However, the saturated fatty acid monoamide type is effective only by the combination of alkyl ketene dimer (AKD), and the combination of rosin and alkenyl succinic anhydride (ASA) increases the drying load. In the saturated fatty acid amide type and the saturated fatty acid polyamide type, any combination of AKD, rosin and ASA is effective.

Moreover, 0.1-2.0% is preferable and 0.5-1.2% is more preferable, as for the addition amount of the bulking agent to all the pulps on the basis of the absolute dry weight of all the pulps. If it is less than 0.11%, there is almost no bulky effect, and even if added over 2.0%, the bulk does not increase any more. Further, if the coating amount of the starch-based surface paper strength agent is less than 0.1 g / m ^2, it is difficult to suppress bleed, and if the coating amount exceeds 3.0 g / m ² , the density of the paper increases. Therefore, it is not preferable.

Paper making of the bulky medium-sized book 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.
The type of the apparatus for applying the starch-based surface paper strength agent is not particularly limited, and can be applied by a coating machine such as a two-roll size press coater, a gate roll coater, a blade metering coater, or a rod metering coater. . Other papermaking conditions are not particularly defined, and the pH during papermaking may be acidic, neutral or alkaline.

The bulky medium-size book paper of the present invention may appropriately contain a filler.
For example, white carbon, talc, kaolin, clay, heavy calcium carbonate, light calcium carbonate, titanium oxide, synthetic resin filler or light calcium carbonate-silica in which the surface of light calcium carbonate particles is coated with silica. Known fillers such as composites can be used.

The content of the filler is preferably 1 to 20% by weight, more preferably 3 to 15% per paper weight. When the content exceeds 20% by weight, when the starch-based surface paper strength agent is applied with a size press coater, the amount of liquid absorption increases, the drying load increases, and the paper making speed decreases.
In addition, the bulky medium-sized book paper of the present invention is used for papermaking such as sulfate bands, various anionic, cationic, nonionic or amphoteric yield improvers, freeness improvers, paper strength enhancers, or 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 adjusting agent, an antifoaming agent, a pitch control agent or a slime control agent is added as necessary.

For the purpose of surface strength or sizing performance improvement, the starch-based surface paper strength agent to the surface of the base paper 0.3 to 4.0 g / m ^2, preferably may be ² applied 0.5 to 3.0 g / m .
The type of starch used for the starch-based surface strength agent used here is not particularly limited, and raw starch, oxidized starch, dialdehyde starch, phosphate-modified starch, hydroxyethylated starch, hydroxypropylated starch, cationized starch Alternatively, processed starch such as enzyme-modified starch can be used.
In addition, other water-soluble polymers may be mixed and applied in combination, and as these water-soluble polymers, those usually used as surface treatment agents such as carboxymethyl cellulose, polyacrylamide or polyvinyl alcohol are used alone. Or 2 or more types can be used together. In addition, a paper strength enhancer for the purpose of water resistance and surface strength improvement and an externally added sizing agent for the purpose of imparting sizing can also be added.

As described above, in the present invention, the constituent pulp contains bleached kraft pulp and bleached thermomechanical pulp (especially bleached thermomechanical pulp of hardwood is preferable), and the composition weight ratio of bleached kraft pulp and bleached thermomechanical pulp is 60/40 to 90/10, and the freeness of the whole pulp is 250 to 350 ml CSF, and the density is 0.45 to 0.55 g / cm ³ by containing a saturated fatty acid amide based bulking agent. The whiteness is 77 to 83% higher than the conventional 65 to 75%, but the whiteness is high, and the bulky medium-sized book paper that is flexible and excellent in printability is obtained. Can do. At the same time, a decrease in papermaking speed can be suppressed, and a bulky medium-sized book paper having good operability can be obtained.

Examples are shown below, but these examples do not limit the scope of the present invention.
In the description, parts are parts by weight, and% is solid content weight%.
In addition, the paper quality measuring method and the bulking agent used in the examples are shown below.

<Paper quality measurement method>
Density: Measured according to JIS P 8118.
-Whiteness: Measured according to JIS P 8123.
-Breaking length: measured according to JIS P 8113.
-PPS roughness: measured according to ISO8791 and measured by soft backing.

<Sample bulking agent>
Bulking agent A: Saturated fatty acid monoamide type Bulking agent B: Saturated fatty acid diamideamine type Bulking agent C: Saturated fatty acid polyamide polyamine type Bulking agent D: Polyhydric alcohol saturated fatty acid ester type Bulking agent E: Higher alcohol alkyl oxide Adducts and bulking agents F: unsaturated fatty acid diamidoamines
[Example 1]

NBKP (freeness 600mlCSF, ISO whiteness 84%) 15 parts, LBKP (freeness 300mlCSF
ISO pulp 86%) 60 parts, NTMP (freeness 100mlCSF, ISO whiteness 70%) mixed with a ratio of 25 parts free pulp slurry 290mlCSF, sulfuric acid band 0.8%, cationic starch 1%, polyacrylamide 0.2%, adding bulky agent a 0.5% addition of retention aid 200 ppm, and paper making by Fourdrinier paper machine, coating and the coating amount of 3 g / m ² of oxidized starch by a 2-roll size press coater It was dried to obtain a bulky medium-quality printing paper having a basis weight of 87 g / m ² .
[Example 2]

A bulky medium-sized printing paper was obtained under the same conditions as in Example 1 except that the bulking agent B was used in place of the bulking agent A of Example 1.
[Example 3]

A bulky medium-sized printing paper was obtained under the same conditions as in Example 1 except that the bulking agent C was used in place of the bulking agent A of Example 1.
[Example 4]

Example 1 with the exception that the pulp formulation was 90 parts LBKP (freeness 300 mlCSF, ISO whiteness 86%) and NTMP (freeness 100 mlCSF, ISO whiteness 70%) 10 parts, and the pulp freeness was 280 mlCSF. A bulky medium-size printing paper was obtained under the same conditions as in Example 1.
[Example 5]

The pulp composition is NBKP (freeness 600mlCSF, ISO whiteness 84%) 15 parts, LBKP (freeness 300mlCSF, ISO whiteness 86%) 45 parts, NTMP (freeness 100mlCSF, ISO whiteness 70%) 40 parts A bulky medium-quality printing paper was obtained under the same conditions as in Example 1 except that the pulp freeness was 260 ml CSF.
[Example 6]

The pulp composition is NBKP (freeness 600 mlCSF, ISO whiteness 84%) 15 parts, LBKP (freeness 300 mlCSF, ISO whiteness 86%) 60 parts, LTMP (200 mlCSF, ISO whiteness 77%) 25 parts A bulky medium-size printing paper was obtained under the same conditions as in Example 1 except that the pulp freeness was 320 ml CSF.
[Comparative Example 1]

A bulky medium-sized printing paper was obtained under the same conditions as in Example 1 except that the bulking agent D was used in place of the bulking agent A of Example 1.
Made paper.
[Comparative Example 2]

A bulky medium-sized printing paper was obtained under the same conditions as in Example 1 except that the bulking agent E was used in place of the bulking agent A of Example 1.
[Comparative Example 3]

A bulky medium-sized printing paper was obtained under the same conditions as in Example 1 except that the bulking agent F was used instead of the bulking agent A of Example 1.
[Comparative Example 4]

A bulky medium-sized printing paper was obtained under the same conditions as in Example 1 except that the pulp content was 100 parts of LBKP (freeness 300 mlCSF, ISO whiteness 86%).
[Comparative Example 5]

Pulp blended NBKP (freeness 600mlCSF, ISO whiteness 84%) 15 parts, LBKP (freeness 300mlCSF, ISO whiteness 86%) 35 parts, NTMP (freeness 100mlCSF, ISO whiteness 70%) 50 parts A bulky medium-sized printing paper was obtained under the same conditions as in Example 1 except that the pulp freeness was 240 ml CSF.
[Comparative Example 6]

Pulp drainage at a ratio of 15 parts NBKP (freeness 600 mlCSF, ISO whiteness 84%), 35 parts LBKP (300 mlCSF, 86% ISO whiteness), 50 parts LTMP (200 mlCSF, ISO whiteness 77%) A bulky medium quality printing paper was obtained under the same conditions as in Example 1 except that the degree was 310 ml CSF.
[Comparative Example 7]

The pulp composition is NBKP (freeness 600 mlCSF, ISO whiteness 84%) 15 parts, LBKP (freeness 420 mlCSF, ISO whiteness 86%) 60 parts, NTMP (100 mlCSF, ISO whiteness 77%) 25 parts A bulky medium-sized printing paper was obtained under the same conditions as in Example 1 except that the pulp freeness was 370 ml CSF.
[Comparative Example 8]

The pulp composition is NBKP (freeness 600mlCSF, ISO whiteness 84%) 15 parts, LBKP (freeness 200mlCSF, ISO whiteness 86%) 60 parts, LTMP (200mlCSF, ISO whiteness 77%) 25 parts. A bulky medium-sized printing paper was obtained under the same conditions as in Example 1 except that the pulp freeness was 230 ml CSF.
Table 1 shows the results.

From the results of Table 1 above, Examples 1 to 5 based on the present invention have a low whiteness and extremely high whiteness and good smoothness, so that the printing finish is good and further the reduction in papermaking speed can be suppressed. It can be seen that a bulky medium-size book paper having good properties can be obtained.
From the comparison between Examples 1, 2 and 3 and Comparative Examples 1 and 2, it is not possible to reduce the density of medium-sized book paper to a low density of 0.55 g / cm ³ or less with bulking agents other than aliphatic amides. Recognize. It can be seen that Comparative Example 2 using a higher alcohol alkyloxide bulking agent and Comparative Example 3 using an unsaturated fatty acid diamidoamine bulking agent are slow in paper making and poor in workability.
That is, it can be seen from the comparison between Example 1 and Comparative Example 4 that the density of medium-size book paper cannot be reduced to 0.55 g / cm ³ or less without the blending of bleached TMP. From the comparison of Example 5 and Comparative Example 5, it was found that the smoothness deteriorated in the case of NTMP when the blending ratio of bleached TMP was more than 40%, and in the case of LTMP in Comparative Example 6, the paper strength was greatly reduced. Paper breakage occurred and papermaking was not possible. From Comparative Example 7, it can be seen that when the pulp freeness exceeds 350 ml CSF, the paper making speed is lowered and the smoothness is deteriorated. From Comparative Example 8, it can be seen that if the pulp freeness is less than 250 ml CSF, the density cannot be reduced to 0.55 g / cm ³ or less.

Taking the above results comprehensively, the constituent pulp includes bleached kraft pulp and bleached thermomechanical pulp (especially bleached hardwood bleached thermomechanical pulp is preferred), and the composition weight ratio of bleached kraft pulp and bleached thermomechanical pulp is In the range of 60/40 to 90/10, the total pulp freeness is 250 to 350 ml CSF, and the density is 0.45 to 0.55 g / cm by containing a saturated fatty acid amide based bulking agent. ^Although it is a low density of ³ , the whiteness is 77 to 83% as compared with the conventional whiteness of 65 to 75%, and it is obtained that it is a bulky medium-sized book paper having a very high whiteness and excellent printability. I understood it.
At the same time, it became clear that a decrease in papermaking speed can be suppressed and a bulky medium-sized book paper with good operability can be produced.

Claims (2)

Contains bleached kraft pulp and bleached thermomechanical pulp, the composition weight ratio of bleached kraft pulp and bleached thermomechanical pulp is 60/40 to 90/10, and the freeness of all pulp is 250 to 350 mlCSF, saturated Contains a fatty acid amide-based bulking agent, coated with a starch-based surface paper strength agent by a 2-roll size press coater , with a density of 0.45-0.55 g / cm ³ and a whiteness of 77-83% Bulky medium-sized book paper characterized by being.   The bulky medium-sized book paper according to claim 1, wherein the bleached thermomechanical pulp is bleached hardwood thermomechanical pulp.