JP6436732B2 - Book paper - Google Patents

Description

  The present invention relates to a book paper in which sticking of a small edge surface is reduced when polishing a booklet that has been bound.

  Generally, books are distributed based on a consignment system in which publishers line up at bookstores through a distributor, and usually 30 to 40% of books that could not be sold at bookstores are returned. The returned books will be sent again to other bookstores as merchandise, but once they have been manufactured, such as once displayed at the storefront, the small face will fade. Then, a small surface polishing process called “renovation” using a polishing machine is performed.

  However, the polished surface after this polishing process has interpage between the wood pulp fibers that are the raw material of the book paper and the adhesive of the clear coating layer that has been processed to prevent surface properties during printing. Sticking may occur, making it difficult to open the page. The “sticking” (also referred to as blocking) on the small face when refurbishing a booklet that has been bound requires the page to be paged one by one to solve the problem, and the work is complicated. In addition, there is a risk that merchandise for which “sticking” could not be distributed will be distributed to bookstores, etc., and improvement of small sticking by renovation is required.

As a technology for eliminating the sticking of the small edge surface during polishing, a technology relating to printing paper containing regenerated particle aggregates mainly composed of deinking floss as filler and pigment, and ash content in the paper of 10 to 25% (Patent Document 1) and 40 to 70% by weight of the total pulp component is mechanical pulp, and 50 to 100% by weight of the paper is composed of pressurized stone ground pulp. The technique (patent document 2) etc. regarding the medium-sized book paper which apply | coated 0.7-1.5 g / m < ² > of the clear size agent are illustrated.

JP 2007-2111374 A JP 2005-133244 A

  In the conventional techniques that are generally known, the following problems occur. That is, the technique described in Patent Document 1 has a technical problem of slip generated by providing a pigment coating layer, and is not a technique related to non-coated paper that does not have a pigment coating layer. . On the other hand, although the technique described in the cited document 2 is a technique related to the sticking of the polished surface in non-coated paper (clear coated paper), a technical problem from the pulp surface using special pulp (pressed stone ground pulp). This is a technology corresponding to the above, and no study has been made in terms of the clear coating layer.

  In view of such a situation, an object of the present invention is to provide a non-coated book sheet that prevents sticking of a small edge when a booklet that has been bound is refurbished.

As a result of intensive studies on the above problems, the present inventors have found that in an uncoated book paper having a basis weight of 40 g / m ² or more and a density of 1.0 g / cm ³ or less, the average fiber length is 0.86 mm or less. By applying a clear coating layer containing at least a styrene-butadiene latex and starch as an adhesive on the base paper obtained using a short pulp fiber, the sticking of the small edge during renovation is effective. The present invention has been completed by finding that suppressed book paper can be obtained.

That is, although not limited thereto, the present invention includes the following contents.
(1) A clear coating layer containing a styrene-butadiene latex and starch is provided on the base paper, the average fiber length of the pulp constituting the base paper is 0.86 mm or less, the basis weight is 40 g / m ² or more, and the density Is a book paper of 1.0 g / cm ³ or less.
(2) The book paper according to (1), wherein the base paper contains talc.
(3) The book paper according to (1) or (2), wherein the starch is oxidized starch.
(4) The book paper in any one of (1)-(3) whose average particle diameter of the said latex is 70 nm-90 nm or less.
(5) The book paper in any one of (1)-(4) whose weight ratio of latex and starch is latex: starch = 10: 90-99: 1.
(6) The book paper according to any one of (1) to (5), wherein the ash content in the paper is 5% by weight to 30% by weight.
(7) A booklet obtained by binding the book paper according to any one of (1) to (6).
(8) A method for producing a book paper according to any one of (1) to (6), wherein a process for making a base paper using pulp having an average fiber length of 0.86 mm or less, and a styrene-butadiene system And a step of applying a clear coating layer containing latex and starch on the base paper.
(9) A method for suppressing sticking between sheets when a booklet that has been bound is refurbished, wherein the book sheet according to any one of (1) to (6) is used as a sheet constituting the booklet. A method as described above, characterized in that it is used.

  The book paper of the present invention has an effect that, when the book paper is bound, the sticking of the facet when refurbished is effectively suppressed. The book paper of the present invention is particularly suitable as a book paper because it has excellent printability and processability.

Book paper The present invention relates to book paper. In the present invention, the book paper is non-coated paper mainly used for books. Since it is used as a book, it is generally demanded that it is excellent in printability and has high visibility even when it is read for a long time and eyes are not tired. Also, since bookbinding is generally used, it is preferable to adjust the stiffness (stiffness) of the paper so that it is easier to turn when binding, and as a recent trend, even if the number of pages decreases, There is a case where low density (bulkyness) is required so as not to impair the volume feeling.

The book paper of the present invention has a basis weight measured according to JIS P 8124 of 40 g / m ² or more, preferably 45 g / m ² or more, more preferably 50 g / m ² or more. The upper limit is not particularly a basis weight, is preferably 100 g / ^{m 2} or less, more preferably 95 g / ^{m 2} or less. Further, the paper thickness of the book paper of the present invention is not particularly limited, but the paper thickness measured according to JIS P 8118 is preferably 40 μm or more, more preferably 55 μm or more, and 60 μm or more. Further preferred.

The book paper of the present invention has a paper density measured according to JIS P 8118 of 1.0 g / cm ³ or less, preferably 0.95 g / cm ³ or less, more preferably 0.90 g / cm ³ or less. More preferably, it is 0.85 g / cm ³ or less, and most preferably 0.80 g / cm ³ or less. With such a density, sticking of the facet at the time of refurbishment is reduced, and since the density is low, the volume of the book can be maintained even if the number of pages is reduced. Although there is no particular lower limit of the density, from the viewpoint of maintaining the smoothness required for book paper, is preferably 0.40 g / cm ³ or more, and more preferably 0.50 g / cm ³ or more.

  The book paper of the present invention has an ISO opacity measured according to ISO 2471 of preferably 80 or more, and more preferably 85 or more. If the ISO opacity level is low, a show-through occurs during printing, and the book tends to be difficult to read when bound.

Base Paper The book paper of the present invention has a clear coating layer mainly composed of an adhesive on a base paper made from paper. In addition to pulp fibers, the base paper is internally filled with a filler as necessary.

  The paper stock used in the present invention comprises a pulp raw material. As described above, the base paper used for the book paper of the present invention is made from pulp having an average fiber length of 0.86 mm or less. The average fiber length of the pulp constituting the base paper is a length-weighted average measured by using a Fiber Tester manufactured by L & W Co., Ltd., by preparing a pulp slurry by disassembling book paper in accordance with JIS P 8220. By shortening the average fiber length of the whole pulp to be used to 0.86 mm or less, it is considered that the entanglement between the fibers is suppressed, and the sticking of the small edge during remodeling is reduced. In a preferred embodiment, the average fiber length of the pulp is preferably 0.84 mm or less. The lower limit of the average fiber length of the pulp is not particularly limited, but is preferably 0.70 mm or more, and may be 0.75 mm or more. In the present invention, the average fiber length of the pulp can be set within a desired range by adjusting the beating conditions, pulp blending, and material type. As beating conditions, for example, the beating load changes depending on the type of beating machine, the shape of the blade (plate), the distance between the blades and the blade, and the flow rate and concentration of pulp processed by the beating machine. The fiber length can be adjusted. The degree of beating can be evaluated using, for example, Canadian Standard Freeness (CSF) as an index, as can be understood by an engineer in the paper industry.

  Moreover, there is no restriction | limiting in particular in the pulp raw material to be used, In addition to wood pulp, such as softwood pulp (NP) and hardwood pulp (LP), non-wood pulp, such as linter pulp, hemp, bagasse, kenaf, esparto grass, and straw, Semi-synthetic fibers such as rayon and acetate, synthetic fibers such as polyolefin, polyamide, and polyester can be used. Specifically, what is commonly used as a papermaking raw material for printing paper such as mechanical pulp (MP), deinked pulp (DIP, also called waste paper pulp), kraft pulp (KP), etc. should be used suitably. As appropriate, one or more of these may be used in combination. Examples of the mechanical pulp include groundwood pulp (GP), refiner groundwood pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), chemiground pulp (CGP), semi-chemical pulp (SCP), and the like. . Deinked pulp includes high-quality paper, medium-quality paper, low-grade paper, newsprint, flyers, magazines, etc., as well as unsorted waste paper mixed with these, copy paper, thermal paper, carbonless paper, confidential waste paper, etc. There is no particular limitation as long as it is a deinked pulp made from waste office paper containing. In general, hardwood pulp has a short fiber length compared to softwood pulp. Therefore, by increasing the amount of hardwood pulp used, the average fiber length of all pulps constituting the base paper can be set within the scope of the present invention. In general, the fiber length of deinked pulp (DIP) tends to be shorter than that of virgin pulp. By increasing the amount of DIP used, the average fiber length of all pulps constituting the base paper is reduced. can do. For example, in a preferred embodiment, the amount of hardwood pulp used relative to the whole pulp can be 30% by weight or more, or 40% by weight or more. Moreover, in another preferable aspect, the usage-amount of DIP with respect to the whole pulp can be 20 weight% or more, and is good also as 30 weight% or more. In a preferred embodiment of the present invention, as the pulp constituting the base paper, 30% by weight or more of hardwood pulp and 20% by weight or more of DIP can be used. There is no particular upper limit on the amount of hardwood pulp or DIP used, but it is preferably used in an amount of 90% by weight or less of the pulp constituting the base paper.

  The base paper used in the present invention may contain a filler. The type of filler is not particularly limited, but a particularly preferred filler is talc. Talc is a white particle mainly composed of hydrous magnesium silicate (3MgO · 4SiO 2 · H 2 O), and has a layered structure in which a silica / magnesium hydroxide layer is provided between silica layers. It is also called talc, and its main production areas are China, South Korea, the United States and Australia. When talc is used as an internal filler in the book paper of the present invention, it is possible to improve the printing quality such as opacity, smoothness, and printability, and to prevent sticking of the fore edge during polishing due to a decrease in friction coefficient. .

  Various internal additives may be added to the stock of the present invention as long as the effects of the present invention are not impaired. The internal additive is not limited to this, but polyacrylamide polymer, polyvinyl alcohol polymer, oxidized starch, esterified starch, cationized starch, other various modified starches, styrene-butadiene copolymer. Adhesives such as latex and vinyl acetate; cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose; internal paper strength enhancers such as urea / formalin resin and melamine / formalin resin; rosin sizing agent, alkyl ketene dimer (AKD) Internally added sizing agents such as sizing agents, alkenyl succinic anhydride (ASA) sizing agents, petroleum sizing agents, and neutral rosin sizing agents; sulfuric acid bands, yield improvers, UV inhibitors, fading inhibitors, and drainage improvements Agent, coagulant, pH adjuster, slime control agent, colorant (dye, face ) And fluorescent dyes, and the like may be added.

  The book paper of the present invention can be used alone or in combination of two or more fillers including the above-mentioned talc, but the filler is not particularly limited and can be used by appropriately selecting from known fillers. . Examples of such fillers include kaolin, clay, organic carbonates such as calcium carbonate such as light calcium carbonate and heavy calcium carbonate, titanium dioxide, silica, and plastic pigment, preferably talc. Light calcium carbonate is used together, but when talc and light calcium carbonate are used together, high opacity can be imparted to the book paper by light calcium carbonate having a high specific scattering coefficient. Book paper is often printed on both sides, and opacity is an important quality item in order to prevent show-through after printing.

  In the book paper of the present invention, the ash content in the paper is preferably 5% by weight to 30% by weight, and more preferably 10% by weight to 28% by weight. If the ash content in the paper is less than 5% by weight, the opacity and smoothness of the resulting book paper may be insufficient. On the other hand, if the ash content in the paper is higher than 30% by weight, the bonding between the fibers is hindered by the filler in the paper, and there is a possibility that the stiffness of the paper is insufficient. The shortage of paper causes problems such as poor processing suitability and turning suitability when processed as a book.

  In the present invention, the stock prepared as described above is appropriately diluted, and after being removed from the stock by a screen or a cleaner as necessary, it is sprayed onto the paper making wire from the head box of the paper machine. The base paper is made. The present invention is manufactured by various paper machines such as a long net type, a circular net type, a short net type, and a twin wire type paper machine. Examples of twin wire paper machines include gap formers and on-top formers. The press linear pressure after paper making is used within the range of normal operation.

  The papermaking method may be neutral papermaking or acidic papermaking, but is preferably neutral papermaking. Specifically, in the present invention, the paper surface pH after papermaking is preferably 5.0 to 9.0, and more preferably 6.0 to 8.0.

Clear coating layer In the present invention, in order to improve surface strength, impart water resistance, printability, etc., the base paper obtained above is coated with a surface treatment liquid mainly composed of an adhesive to perform clear coating. A construction layer is provided. In the present invention, styrene-butadiene latex and starch are used in combination as an adhesive for the clear coating layer. The type of starch is not particularly limited, such as raw starch, oxidized starch, esterified starch, cationized starch, and acetylated tapioca starch as raw materials, such as self-modified starch produced by thermochemical modification or enzyme modification in a paper mill. Preferred examples include modified starches such as starch, aldehyde-modified starch and hydroxyethylated starch. In the present invention, at least a styrene-butadiene latex is used in combination with starch in order to prevent surface strength and sticking during small edge polishing. The average particle diameter of the latex measured by the photon correlation method is preferably 70 nm or more and 90 nm or less, and more preferably 75 nm or more and 85 nm or less. If latex having an average particle size larger than 90 nm is used, the surface strength of the obtained paper may be lowered.

  The weight ratio when using styrene-butadiene latex and starch in combination is preferably 10:90 to 99: 1. More preferably, it is 30: 70-95: 5, More preferably, it is 51: 490-90: 10. When latex is used alone, the cost becomes high, so it is preferable to use it together with starch. However, by increasing the mixing ratio of latex, the effect of preventing sticking of the small edge during polishing of the present invention becomes higher. .

  The mechanism by which the effect of the present invention is manifested by using styrene-butadiene latex and starch together is not clear, and the present invention is not restricted by the following reasoning, but is considered as follows. There is a possibility that the effect of preventing the sticking to the facet during polishing when starch and latex are mixed depends on the water retention of starch and the difference in hygroscopicity between latex and starch. Starch has the property of easily causing gelation when the solid content concentration is high, and it is considered that gelation occurs in the coating layer during the drying process. When a surface treatment solution with high water retention that contains a large amount of starch is used, the surface treatment solution permeates into the base paper between processes from coating to drying, and the surface treatment solution exists only on the very surface of the paper. It will be in a state that does not. For this reason, since the fibers in the paper layer are not coated with the surface treatment agent, fluffing is likely to occur, and the fibers are more likely to be entangled. Therefore, it is considered that the sticking of paper at the time of refurbishment can be effectively suppressed by using styrene-butadiene latex and starch together.

  In addition, it is assumed that books used for polishing a small face are long displayed on a bookshelf such as a bookstore, and moisture absorption occurs during that time. Therefore, when much more highly hygroscopic starch is used, it is assumed that the clear coating layer containing moisture is softened and is likely to be sticky due to polishing during refurbishment.

  In addition to styrene-butadiene latex and starch, the clear coating layer includes cellulose derivatives such as carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, cellulose nanofiber, polyacrylamide, polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, acetoacetyl. It is also possible to use modified alcohol such as fluorinated polyvinyl alcohol, latex other than styrene-butadiene latex, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, polyacrylic ester, etc. It is.

  Also, for the purpose of increasing the size, surface sizing agents such as styrene sizing agents, olefin sizing agents, acrylate sizing agents, styrene-acrylic sizing agents, and cationic sizing agents should be added to the clear coating layer. Is also possible. When using a surface sizing agent, the solid content concentration in the surface treatment agent is preferably 0.05 to 5% by weight, and more preferably 0.05 to 1% by weight.

  Furthermore, in the case of clear coating in the present invention, various additives to be added to a normal surface treatment agent such as a dispersant, a thickener, a water retention material, an antifoaming agent, a water-resistant agent, a colorant, and a conductive agent as necessary. Auxiliaries are used as appropriate.

The coating amount of the clear coating layer is appropriately determined depending on the surface strength required for book paper and the like, and is not particularly limited, but is usually in the range of 0.1 to 10 g / m ^{2 on} both sides. 0.1-5 g / m < ² > is preferable and 0.1-2.0 g / m < ² > is more preferable. When the coating amount increases, the absolute amount of moisture in the coating layer increases, resulting in an increase in the drying load and the occurrence of poor drying. For this reason, the coating layer is increased in stickiness, and sticking is likely to occur when cutting a small face.

  The apparatus for applying the surface treatment agent is not particularly limited, and can be applied by a known coating machine such as a two roll size press, a pound type size press, a gate roll coater, a lot metering size press, a blade coater, a spray coater, or a curtain coater. Can be applied.

  The obtained clear coated paper may be finished by passing it through a known public finishing device such as a super calender, gloss calender, soft calender, high temperature soft nip calender, etc., or untreated or bypassed. Also good.

Clear coated paper dry NePPari evaluation invention, the dry NePPari evaluation, it is preferred that NePPari does not occur. The stickiness evaluation performed by the dry method has a high correlation with the occurrence rate of sticking of the small edge during polishing, and the higher the degree of sticking, the more likely the sticking trouble occurs when polishing the small face of the book.

  The present invention will be described below with reference to examples, but the examples do not limit the scope of the present invention. In the description of the present specification, the concentration and% are based on (solid content) weight, and the numerical range is described as including the end points.

<Evaluation method>
1. Measurement of various paper qualities / basis weight: Measured according to JIS P 8124.
-Paper thickness and density: Measured according to JIS P 8118.
Ash content: Measured according to ISO 1762-1974.
ISO opacity: measured according to ISO 2471.
-Average fiber length: The book paper was disaggregated according to JIS P 8220, the fiber length was measured using a FiberTester manufactured by L & W, and the length weighted average was determined.
2. Evaluation temperature 23 ° C. in a dry NePPari strength, the book paper humidified 50% relative humidity cut into 4 × 6 cm, by superimposing two sheets of coated surface comrades passed through the rolls at a pressure of 50 kg / m ^2. The two-ply sample pressed by the roll was evaluated in three stages for the firmness (ease of sticking between papers) according to the following criteria.
×: Papers are attached and do not separate into two unless peeled. Δ: Papers are attached, but when touched lightly, they are separated into two. ○: Papers are not attached and separated into two. ing
3. Evaluation of small edge sticking A6 size (paperback book size) book paper, 200 sheets of soft cover and bookbinding were performed. Four bookbinding samples were put together in a belt polisher (manufactured by NIPPO), and the facet was polished twice back and forth in accordance with standard usage. About the binding sample which grind | polished the small edge surface, the sticking property of the small edge surface after grinding | polishing according to the following reference | standard was evaluated in four steps.
×: When the book is opened, a plurality of pages are strongly stuck in the polishing part and are difficult to loosen. Δ: When the book is opened, a plurality of pages are stuck in the grinding part, but are easily loosened. There is no sticking to the polishing part
4). Evaluation of surface strength After a solid black ink was printed on a sample of A3 size on a sheet-fed printing press R202 manufactured by Roland, the number of peeled pulp fibers appearing on the surface was visually observed. The dry pick surface strength was evaluated in three stages according to the following criteria.
×: A lot of peeling occurred Δ: A little peeling occurred ○: Little peeling occurred <Manufacture of book paper>
Example 1
A pulp slurry in which 50 parts of hardwood bleached kraft pulp (LBKP, CSF 350 ml), 10 parts of softwood bleached kraft pulp (NBKP, CSF 600 ml) and 40 parts of deinked pulp (DIP, CSF 280 ml) are mixed with talc and calcium carbonate as fillers 8: 19 was added. Furthermore, 1.0% sulfuric acid band, 0.06% internal sizing agent (AKD), 0.3% cationized starch and 0.2% PAM are added to the total weight (solid content) of pulp and filler. A paper stock having a pH of about 7 was prepared.

  Thereafter, the above-mentioned stock was ejected from a head box onto a twin-wire type paper making wire, paper was made, dried with a press part and dried with a predryer, and a base paper was made at a paper making speed of 850 m / min.

Using a gate roll coater (GRC), apply the surface treatment liquid evenly on both sides so that the total coating amount on both sides is 2.4 g / m ² (single side: 1.2 g / m ² ). Coating was performed, and a clear coating layer was provided on the base paper. The surface treatment solution was 70 parts of a starch obtained by dissolving oxidized starch (SK-20 manufactured by Nippon Corn Starch Co., Ltd.) in water and steamed at 95 ° C., and styrene-butadiene latex (PB9501 manufactured by Japan A & L Co., optical correlation method). 30) and 4 parts of a synthetic polymer sizing agent.

After drying, a book paper having a basis weight of 56.8 g / m ² , a paper thickness of 75 μm, and an ash content of 21% was obtained. When this book paper was disaggregated and the average fiber length of the pulp was measured, it was 0.85 mm.

Example 2
A book paper was obtained in the same manner as in Example 1 except that the coating amount of the surface treatment liquid was 1.0 g / m ² (single side: 0.5 g / m ² ) on both sides.

Example 3
Book paper was obtained in the same manner as in Example 1 except that 30 parts of oxidized starch of the surface treatment liquid and 70 parts of styrene-butadiene latex were used.

Example 4
Book paper was obtained in the same manner as in Example 1 except that talc and calcium carbonate were added to the base paper as a filler at a ratio of 11:26 to make the ash content in the paper 29% and the paper thickness 65 μm.

Example 5
Book paper was obtained in the same manner as in Example 1 except that talc and calcium carbonate were added to the base paper as a filler at a ratio of 2: 6 so that the ash content in the paper was 6%.

Example 6
Example 1 except that talc and calcium carbonate as a filler were added to the base paper in a ratio of 8:19 so that the ash content in the paper was 21%, and the particle size of the styrene-butadiene latex in the surface treatment liquid was 110 nm. The book paper was obtained in the same way.

Example 7
A book paper was obtained in the same manner as in Example 1 except that talc was not contained as a filler in the base paper and calcium carbonate was added to make the ash content in the paper 21%.

Example 8
Book paper was obtained in the same manner as in Example 1 except that oxidized starch was not added to the surface treatment solution and 100 parts of styrene-butadiene latex was used.

Example 9
Example 1 except that a pulp slurry in which 50 parts of hardwood bleached kraft pulp (LBKP, CSF 300 ml), 10 parts of softwood bleached kraft pulp (NBKP, CSF 500 ml) and 40 parts of deinked pulp (DIP, CSF 280 ml) were used was used. I got book paper. When this book paper was disaggregated and the average fiber length of the pulp was measured, it was 0.83 mm.

Comparative Example 1
Book paper was obtained in the same manner as in Example 1 except that the basis weight was 39 g / m ² and the paper thickness was 51 μm.

Comparative Example 2
A book paper was obtained in the same manner as in Example 1 except that the paper thickness was 54 μm and the density was 1.05 g / cm ³ .

Comparative Example 3
Book paper was obtained in the same manner as in Example 1 except that 100 parts of oxidized starch of the surface treatment liquid was used and no styrene-butadiene latex was added.

Comparative Example 4
Book paper was obtained in the same manner as in Example 1 except that talc was not used as a filler, the ash content in the paper was 21%, and the surface treatment liquid was not blended with styrene-butadiene latex (100 parts of oxidized starch). .

Comparative Example 5
Same as Example 1 except that 50 parts of hardwood bleached kraft pulp (LBKP, CSF 470 ml), 10 parts of softwood bleached kraft pulp (NBKP, CSF 700 ml) and 40 parts of deinked pulp (DIP, CSF 280 ml) were used. I got book paper. When this book paper was disaggregated and the average fiber length of the pulp was measured, it was 0.88 mm.

  Table 1 shows the evaluation results of the obtained book paper. First, referring to Examples 1 and 9 and Comparative Example 5, by setting the average fiber length of the pulp to 0.86 mm or less, sticking of the facet is effectively suppressed, and the average fiber length is 0.84 mm or less. In particular, particularly good results were obtained (Example 9).

  In addition, referring to Examples 1, 3, 8 and Comparative Example 3, as compared with the case where only starch is used as the binder of the surface treatment liquid (clear coating liquid) (Comparative Example 3), styrene-butadiene together with starch. It became clear that the tenacity of book paper, stickiness of the small edge, and surface strength were all improved by using the latex.

  Furthermore, referring to Comparative Examples 1 and 2, when the basis weight or density of the book paper is outside the range of the present invention, the stickiness of the small edge surface tends to deteriorate. Furthermore, when talc was added to the base paper as a filler, a tendency to improve the stickiness of the small edge surface was also confirmed.

Claims (11)

Styrene - Bei give a clear coating layer containing a butadiene latex and starch on a base paper, basis weight of 40 g / m ² or more, density of a book sheet is 1.0 g / cm ³ or less,
The book paper, wherein 20% or more of the pulp constituting the base paper is deinked pulp, and the average fiber length of the pulp constituting the base paper is 0.86 mm or less . The book paper according to claim 1, wherein 30% or more of the pulp constituting the base paper is hardwood pulp. The book paper of Claim 1 or 2 whose average fiber length of the pulp which comprises a base paper is 0.70 mm or more. The book paper according to any one of claims 1 to 3 , wherein the base paper contains talc. The book paper according to any one of claims 1 to 4 , wherein the starch is oxidized starch. The book paper according to any one of claims 1 to 5 , wherein the latex has an average particle size of 70 nm to 90 nm or less. The book paper in any one of Claims 1-6 whose weight ratio of latex and starch is latex: starch = 10: 90-99: 1. In paper ash content is 5 wt% to 30 wt%, book paper according to any one of claims 1-7. The booklet which bound the book paper in any one of Claims 1-8 . It is a manufacturing method of the book paper in any one of Claims 1-8 ,
A step of making a base paper using pulp having an average fiber length of 0.86 mm or less;
Styrene - a step you coating on base paper clear coating layer containing a butadiene latex and starch,
The above method. A method of suppressing sticking between sheets when refurbishing the small facet of a bound booklet, wherein the book paper according to any one of claims 1 to 8 is used as the paper constituting the booklet. The above method.