JP2013133561A - Paper for book - Google Patents

Abstract

Provided is a book paper that has sufficient paper strength, is supple, is easy to turn pages, and is excellent in touch.
SOLUTION: A book paper, which is coated with a water-soluble metal salt so as to have a content of 1% by mass to 5% by mass with respect to the paper basis weight, and has a Clark stiffness of 35 cm ^{3 in} the horizontal direction of the paper. book paper is in the range of / 100~55cm ^3/100.
[Selection figure] None

Description

  The present invention relates to a book paper that has sufficient paper strength, is flexible, is easy to turn pages, and has excellent touch feeling.

  The book paper is required to have easy touching of the page due to its suppleness or good touch feeling due to its use.

  As means for imparting suppleness, a method of adding a softening agent to raw pulp is known. For example, a method in which the softening agent is a long-chain dialkyl type quaternary ammonium salt type cationic surfactant (for example, see Patent Document 1), and the softening agent is a nonionic such as a cationic surfactant or a polyalkylene alkyl ether. There is a method (for example, refer to Patent Document 2) which is a surfactant. However, the cationic surfactant has a great decrease in the strength of the paper, and its use amount is limited. In addition, nonionic surfactants are poorly fixed on pulp, and the effect of imparting flexibility is not fully satisfied.

  In recent years, it has been desired to reduce the weight of paper from the viewpoint of saving resources and reducing logistics costs. Here, the weight reduction means weight reduction while maintaining the thickness of the paper, that is, bulkiness.

  In order to increase the bulk, a method of suppressing the beating process of pulp, a method of reducing the press pressure in the paper machine press process, and a method of suppressing the calendar process for imparting smoothness are effective. These methods all deteriorate the ease of turning pages or the feeling of touch.

  In order to increase the bulk while providing flexibility, there is a method of adding a bulk softener to the raw material pulp in addition to the above-described bulk increasing method. For example, there are a method in which the bulky softener is a cationic bulky softener (see, for example, Patent Document 3) and a method in which the bulky softener is a nonionic bulky softener (see, for example, Patent Documents 4 and 5). The compositions constituting these bulky softeners are not the same, but they are all types of surfactants, and are techniques for securing bulkiness by fixing to pulp fibers during paper making and increasing the distance between the fibers. That is, the effect is exhibited by inhibiting the hydrogen bond between the pulp fibers, the strength of the paper is greatly reduced, and the offset printability is also lowered.

  In addition, there is a method of applying a softening agent to printing paper using a specific filler (see, for example, Patent Document 6). In this method, sufficient paper strength is not obtained at present.

JP 63-165597 A JP 56-107072 A JP-A-11-269799 JP-A-11-200263 JP 11-350380 A JP 2005-256205 A

  If the strength of the paper is lowered, blanking tends to occur, and the offset printability is lowered. An object of the present invention is to provide a book paper that has sufficient paper strength, is flexible, is easy to turn pages, and has an excellent touch feeling.

As a result of intensive studies in view of the above, the present inventors have applied a water-soluble metal salt so as to have a content of 1% by mass to 5% by mass with respect to the basis weight of the paper. There the book paper in the range of 35cm ³ / 100~55cm ^3/100, leading to satisfy the problem.

  Since the book paper of the present invention to which the above means is applied has sufficient paper strength, it has good offset printing suitability and is supple, and is excellent in page turning ease and touch feeling.

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

  The book paper of the present invention is formed by applying a water-soluble metal salt so as to have a content of 1% by mass to 5% by mass with respect to the paper basis weight. When the book paper contains a water-soluble metal salt, it easily absorbs moisture in the air. As a result, the flexibility increases and the feeling of stickiness is eliminated, resulting in a good hand feeling with a moist feeling. If it is less than 1% by mass, the flexibility is insufficient, the ease of turning the page is insufficient, and the touch feeling is inferior. If it exceeds 5% by mass, the suitability for offset printing and the ease of turning pages will be reduced.

  The water-soluble metal salt used in the present invention refers to a salt containing a cation that can be dissolved in 1% by mass or more in 20 ° C. water. Examples of cations include, for example, monovalent cations such as lithium, sodium, and potassium, magnesium, calcium, strontium, barium, nickel, zinc, iron, copper, cobalt, tin, manganese, and other divalent cations, aluminum , Trivalent cations such as iron and chromium, or tetravalent cations such as titanium and zirconium, and complex ions thereof. The anion that forms a salt with the cation may be either an inorganic acid or an organic acid, and is not particularly limited. Inorganic acids include, but are not limited to, hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, boric acid, hydrofluoric acid, and the like. Examples of organic acids include, but are not limited to, formic acid, acetic acid, lactic acid, citric acid, oxalic acid, succinic acid, and organic sulfonic acid.

  The water-soluble metal salt used in the present invention is preferably a water-soluble metal salt having deliquescence. For example, water-soluble metal salts such as aluminum chloride, calcium chloride, magnesium chloride, aluminum nitrate, calcium nitrate, magnesium nitrate, and sodium nitrate. Since the water-soluble metal salt having deliquescence has a certain level of hygroscopicity, it can easily retain moisture in the paper, and can exhibit the effects of the present invention with a smaller content, which is advantageous in terms of cost.

  In the present invention, as a method for containing a water-soluble metal salt in book paper, a size press process installed in a paper machine, for example, an applied on-machine coater such as an incline size press or a film transfer coater is applied and adhered. The method is preferred. It is considered that more water-soluble metal salt can be retained on the surface of the paper by applying the material to the paper material instead of being added internally, and the touch feeling is improved. For example, the effect of the present invention can be obtained even when coating is performed with an off-machine coater such as an air knife coater, a blade coater, or a roll coater. However, there is no special advantage to apply by an off-machine coater, and an on-machine application method is preferable from the viewpoint of cost. The content of the water-soluble metal salt that is 1% by mass to 5% by mass with respect to the paper basis weight is preferably distributed evenly between the front and back of the book paper. When the distribution is remarkably different between the front and back sides, the feel on the surface of the paper is different between the front and back sides, and the ease of turning pages is reduced. The front / back difference is preferably within 10% by mass. The difference between the front and the back can be adjusted by the coating amount when the water-soluble metal salt is applied.

  As a method for incorporating a water-soluble metal salt into a book paper, there is a method in which a water-soluble metal salt is blended into a paper stock and internally added in a papermaking process. In this method, the water-soluble metal salt is dissociated into a metal cation and an acid anion in the sample. The dissociated metal cation binds to the pulp, and the dissociated acid anion reacts with the filler or the like. That is, after the paper making process, the internally added water-soluble metal salt does not exist as a salt, and the ratio of the salt is greatly reduced. In the present invention, the presence of the water-soluble metal salt absorbs moisture in the air and the effects of the present invention can be obtained. Therefore, the method of adding the water-soluble metal salt to the paper stock and adding it internally is not preferred. For example, a sulfuric acid band (aluminum sulfate) known as a yield improver is generally added to a sample. Yield improvement effect is obtained by the interaction of aluminum ions with pulp. Therefore, the sulfuric acid band blended into the sample and added internally cannot exist as a water-soluble metal salt, and the effects of the present invention are difficult to obtain.

The content of the water-soluble metal salt contained in the book paper can be determined by the following method.
It can be determined by placing a book paper of a predetermined area in predetermined 50 ° C. warm water and measuring the amount of the water-soluble metal salt that is dissolved and extracted into the water.

  In the present invention, it is preferable that the equilibrium water content of the book paper at 23 ° C. and 50% RH is in the range of 6% by mass to 10% by mass. If it is less than 6% by mass, the feel of touch is inferior, and if it exceeds 10% by mass, the feel of touch is good. Depending on the additive contained in the book paper, by setting the water-soluble metal salt content in the book paper in the range of 1% to 5% by weight with respect to the paper basis weight, the paper at 23 ° C. and 50% RH The equilibrium water content can be in the range of 6% by mass to 10% by mass.

In the present invention, short grain direction Clark stiffness of books paper ^is in the range of 35cm ³ / 100~55cm 3/100. When a book paper is used as a magazine or paperback book, it is usually collated so that the vertical direction of the magazine or paperback book and the papermaking direction (longitudinal direction) of the paper are aligned. For this reason, the flexibility when turning pages has a high correlation with the Clark stiffness in the direction of the horizontal direction of the paper. If it is less than 35cm ^3/100, page is less likely to turn to because it is too soft, and when it is more than 55cm ^3/100, so inferior in turning ease and feel a sense of page feel the hardness. Also, the open state cannot be maintained sufficiently. The Clark stiffness can be adjusted by the amount of filler added internally with the pulp, the amount of water-soluble metal salt, and the amount of softener added.

  The book paper of the present invention is preferably a paper formed from a paper stock mainly composed of cellulose pulp and a filler. As the cellulose pulp, chemical pulp such as LBKP and NBKP, mechanical pulp such as GP, PGW, RMP, TMP, CTMP, CMP, and CGP, and waste paper pulp such as DIP are used alone or in combination. In order to obtain bulky book paper, it is useful to use mechanical pulp.

  As fillers used in the present invention, conventionally known various fillers such as heavy calcium carbonate, light calcium carbonate, kaolin, talc, clay, titanium dioxide, aluminum hydroxide, silica, alumina, organic pigments, etc. are used alone or in combination. Used.

  The book paper of the present invention is blended with various additives such as a sizing agent, a fixing agent, a retention agent, a cationizing agent, and a paper strength enhancer in addition to cellulose pulp and filler, if necessary, Papermaking can be performed by various paper machines such as a circular net paper machine and a twin wire paper machine.

  In the present invention, other additives such as an antifoaming agent, an antifoaming agent, a penetrating agent, a coloring dye, a coloring pigment, a fluorescent brightening agent, an ultraviolet absorber, an antioxidant, a preservative, etc. It can also be contained in the paper material as long as it is not impaired.

  The book paper of the present invention can be used as it is, but the surface can be smoothed by a machine calendar, a soft nip calender, a super calendar, or the like, if necessary.

When bulky book paper having a density of 0.65 g / cm ³ or less is required, a method for suppressing pulp beating, a method for reducing the press pressure in the paper machine press step, and for imparting smoothness A method for suppressing the calendar process or the like can be used alone or in combination. All of these methods tend to reduce the flexibility and deteriorate the ease of turning pages and the feeling of touch. However, the book paper of the present invention can provide a bulky book paper that is easy to turn pages and has a good touch feeling without lowering flexibility by adopting these methods.

  The book paper of the present invention can be used not only for offset printing but also for other printing methods such as gravure printing and inkjet printing, and is not limited at all.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. Further, “parts” and “%” shown in the examples indicate parts by mass and mass% unless otherwise specified.

Example 1
To a pulp slurry consisting of 100 parts of LBKP having a freeness of 400 mlcsf, 20 parts of light calcium carbonate (trade name: TP-121, manufactured by Okutama Kogyo Co., Ltd.) as a filler, amphoteric starch (trade name: Cato 3210, manufactured by NSC Japan) 0.8 Part, sulfuric acid band 0.5 part, alkyl ketene dimer type sizing agent (trade name: Size Pine K903, manufactured by Arakawa Chemical Co., Ltd.) 0.12 parts, paper making with a long net paper machine, an incline size press Oxidized starch (trade name: MS # 3800, manufactured by Nippon Shokuhin Kako Co., Ltd.) with a solid content on both sides of 3.0 g / m ² , a surface sizing agent (trade name: Polymaron 385, manufactured by Arakawa Chemical Industries) the 0.05 g / ^{m 2,} the magnesium sulfate was coated so as to be 1.0 g / ^{m 2} as a water-soluble metal salt, subjected to mild machine calendering treatment, basis weight 77. g / ^{m 2,} a density to produce a book paper of Example 1 is 0.81 g / cm ^3.

(Example 2)
A book paper of Example 2 was produced in the same manner as in Example 1 except that the solid content adhesion amount on both sides of magnesium sulfate was 2.0 g / m ² .

(Example 3)
A book paper of Example 3 was produced in the same manner as in Example 1 except that the solid content adhesion amount on both sides of magnesium sulfate was 3.5 g / m ² .

Example 4
A book paper of Example 4 was produced in the same manner as in Example 1 except that magnesium sulfate was replaced with calcium chloride.

(Example 5)
In Example 2, the book paper of Example 5 was produced in the same manner as Example 2 except that magnesium sulfate was changed to calcium chloride.

(Example 6)
In Example 3, the book paper of Example 6 was produced in the same manner as Example 3 except that magnesium sulfate was changed to calcium chloride.

(Example 7)
A book paper of Example 7 was produced in the same manner as in Example 1 except that magnesium sulfate was changed to calcium nitrate.

(Example 8)
A book paper of Example 8 was produced in the same manner as in Example 2 except that magnesium sulfate was replaced with calcium nitrate.

Example 9
In Example 3, a book paper of Example 9 was produced in the same manner as Example 3 except that magnesium sulfate was changed to calcium nitrate.

(Example 10)
A pulp slurry comprising 70 parts LBKP having a freeness of 400 mlcsf and 30 parts TMP having a freeness of 130 mlcsf, 20 parts of light calcium carbonate (trade name: TP-121, manufactured by Okutama Kogyo Co., Ltd.), amphoteric starch (trade name: Cato3210, Nippon NSC Co., Ltd.) 0.8 parts, sulfuric acid band 0.5 parts, alkyl ketene dimer type sizing agent (trade name: Size Pine K903, Arakawa Chemical Industries) 0.12 parts were added, In an inked size press, oxidized starch (trade name: MS # 3800, manufactured by Nippon Shokuhin Kako Co., Ltd.) with a solid content on both sides of 3.0 g / m ² , a surface sizing agent (trade name: Polymaron) 385, manufactured by Arakawa chemical Industries, Ltd.) and 0.05 g / ^{m 2,} calcium chloride was applied so as to be 1.0 g / ^{m 2} as a water-soluble metal salts, pressing pressure, Ma Performs modulation of down calendar, a basis weight of 66.3 g / ^{m 2,} a density to produce a book paper of Example 10 is 0.63 g / cm ^3.

(Example 11)
In Example 10, the book paper of Example 11 was produced in the same manner as in Example 10 except that the solid content on both surfaces of calcium chloride was 2.0 g / m ² .

(Example 12)
In Example 10, a book paper of Example 12 was produced in the same manner as Example 10 except that calcium chloride was changed to calcium nitrate.

(Example 13)
A book paper of Example 13 was produced in the same manner as in Example 11 except that calcium chloride was changed to calcium nitrate in Example 11.

(Comparative Example 1)
In Example 1, a book paper of Comparative Example 1 was produced in the same manner as in Example 1 except that the solid content adhesion amount on both sides of magnesium sulfate was 0 g / m ² .

(Comparative Example 2)
In Example 1, light calcium carbonate (trade name: TP-121, manufactured by Okutama Kogyo Co., Ltd.) was changed from 20 parts to 30 parts, and the solid content on both sides of magnesium sulfate was changed to 0 g / m ^2. In the same manner as in Example 1, a book paper of Comparative Example 2 was produced.

(Comparative Example 3)
In Example 1, 1.0 part of a softening agent (trade name: Sofnon SSK-15, manufactured by Toho Chemical Industry Co., Ltd.) was added to the pulp slurry, and the solid content on both sides of magnesium sulfate was 0 g / m ^2. Produced the book paper of Comparative Example 3 in the same manner as in Example 1.

(Comparative Example 4)
In Example 1, a book paper of Comparative Example 4 was produced in the same manner as in Example 1 except that the solid content on both sides of magnesium sulfate was 0.5 g / m ² .

(Comparative Example 5)
In Example 4, a book paper of Comparative Example 5 was produced in the same manner as in Example 4 except that the solid content adhesion amount on both sides of calcium chloride was 4.5 g / m ² .

(Comparative Example 6)
In Example 1, a book paper of Comparative Example 6 was prepared in the same manner as in Example 1 except that 5 parts of light calcium carbonate (trade name: TP-121, manufactured by Okutama Kogyo Co., Ltd.) as a filler was used.

(Comparative Example 7)
In Example 10, a book paper of Comparative Example 7 was produced in the same manner as in Example 10 except that the solid content on both surfaces of calcium chloride was changed to 0 g / m ² .

(Comparative Example 8)
In Example 10, 1.0 part of a bulking agent (trade name: Meika Softer SH-175Z, manufactured by Meisei Chemical Industry Co., Ltd.) was added to the pulp slurry, and the solid content adhesion on both sides of calcium chloride was 0 g / m ^2. Produced the book paper of Comparative Example 8 in the same manner as Example 10.

  The book papers of Examples 1 to 13 and Comparative Examples 1 to 8 were evaluated for each characteristic by the method described below, and the results are shown in Table 1.

<Water-soluble metal salt content>
As for the content of the water-soluble metal salt, 10 book sheets of 10 cm square (equivalent to 0.1 m ² ) were stirred in 1000 ml of warm water at 50 ° C. The amount of the water-soluble metal salt dissolved and extracted was measured. The measured value was multiplied by 10 and the percentage divided by the basis weight was taken as the water-soluble metal salt content (%) relative to the paper basis weight.

<Clark Stiffness>
According to JIS P 8143, the Clark stiffness of the book paper in the horizontal direction was measured.

<Equilibrium moisture of paper>
The equilibrium moisture of the paper was measured according to JIS P 8127 using a book paper conditioned in an environment of 23 ° C. and 50% RH according to JIS P 8111.

<Offset printing aptitude>
Using an offset sheet-fed printing press manufactured by Mitsubishi Heavy Industries, Ltd., printing speed: 8000 sheets / hour, ink used: DIC Graphics Fusion-GEZ Ink ink is used to print 5000 sheets. The state was determined by visual evaluation. If the evaluation is 3 to 5, there is no practical problem.
5: Extremely good.
4: Good.
3: Range in which there is no practical problem.
2: Defect.
1: Extremely bad.

<Ease of turning pages>
We asked 20 monitors to determine the ease of turning the page of the sample that was collated so that the vertical direction of the book and the paper making direction (longitudinal direction) were aligned, and the average value of 20 people (decimal point) It was expressed as rounded off below. If the evaluation is 3 to 5, there is no practical problem.
5: Very easy to turn.
4: Easy to turn.
3: Neither.
2: It is hard to turn.
1: Very difficult to turn.

<Hand feeling>
20 monitors have the following criteria to determine the feel when turning the pages of a sample that has been collated so that the vertical direction of the book and the paper making direction (longitudinal direction) are aligned. Expressed as (rounded to the nearest decimal place). If the evaluation is 3 to 5, there is no practical problem.
5: Very moist.
4: Moist.
3: Neither.
2: It is cluttered.
1: Very cluttered.

From Table 1, it was applied to water-soluble metal salts such as the content of 1 wt% to 5 wt% with respect to the paper basis weight, of short grain direction Clark stiffness of 35cm ³ / 100~55cm ^3/100 It can be seen that Examples 1 to 9, which are ranges, have good offset printing suitability, and are excellent in the ease of turning pages and the feeling of touch.

Similarly, it is coated with a water-soluble metal salt to the paper basis weight becomes content of 1% to 5% by weight, of short grain direction Clark stiffness of 35cm ³ / 100~55cm ^3/100 range It can be seen that Examples 10 to 13, which are bulky by adjusting the press pressure and the machine calendar, have good offset printing suitability, excellent page turnability, and excellent touch feeling.

  On the other hand, the effects of the present invention cannot be obtained in Comparative Examples 1 to 8 that do not satisfy the conditions of the present invention.

Claims (1)

A book paper, made by coating a water-soluble metal salts such as the content of 1 wt% to 5 wt% with respect to the paper basis weight, short grain direction Clark stiffness of the paper 35cm ³ / 100~55cm Books paper which is a range of ^3/100.