JPWO2015041276A1 - White paperboard and method for producing the same - Google Patents

Abstract

It is an object of the present invention to provide a white paperboard which is bulky and has a high cushioning property, has good printability as a paperboard for printing, and can satisfy all of the various effects of paper processing suitability as paperboard paperboard. LBCTMP, which is a multi-ply white board made of three or more layers and having a bulk of 3.0 to 3.8 cm 3 / g, is added only to the middle layer to 10 to 10 times of the total pulp raw material of the middle layer. It is characterized by blending 50% by weight and combining the surface layer, middle layer and back layer. Preferably, LBCTMP obtained from the genus Maple is blended as the LBCTMP. [Selection figure] None

Description

  The present invention relates to white paperboard and a method for producing the same, and more specifically, covers and texts of publications such as picture books and magazines, printing paperboards such as catalogs, posters, pamphlets, and calendars, and for drawing molding. The present invention relates to a bulky white paperboard used for paperboard for paper containers such as sheets, food paper containers, cup noodle containers, paper cups, confectionery boxes and cigarette cartons, and a method for producing the same.

  Conventionally, the invention related to the paperboard used in the same application as the white paperboard according to the present invention, that is, a paperboard for printing, a paperboard packaging board, or a liner for cardboard, a sheet for drawing, a food paper container, a cup noodle container, etc. Patent Document 1 (Patent No. 3714124) relating to a bulky paperboard that can reduce the weight of the material in paper containers, packaging, and printing as compared with conventional products.

  In this patent document 1, “in the configuration of three or more layers having outer layers on both sides of the middle layer, and the basis weight is 90 to 600 g / m 2, the density of the entire board is 0.50 to 0.75 g / cm 3. The outer layer on at least one side has an outermost layer having a basis weight of 15 to 100 g / m 2 and a density of 0.60 to 0.90 g / cm 3, and the middle layer is made of mechanical pulp, curled fiber and mercerized pulp A bulky paperboard, which is mainly composed of one or more kinds of pulp selected from the above, and has a middle layer density of 0.20 to 0.60 g / cm 3.

  In addition, multilayer paperboard used for paper containers containing oil and moisture foods such as croquettes, cutlets, tempura, french fries, shumai, dumplings, takoyaki, taiyaki, etc., and this multilayer paperboard Patent Document 2 (Japanese Patent No. 4302124) discloses an invention relating to a paper container manufactured by the above method.

  This Patent Document 2 discloses that “basis weight for accommodating a food having oil and moisture is 200 to 530 g / consisting of at least a surface layer, a back layer, and an intermediate layer disposed between the surface layer and the back layer. m2 multilayer paperboard, the intermediate layer containing at least 10% mechanical pulp improves the rigidity and air permeability of the intermediate layer, and the lightness (L value) in the color tone of the intermediate layer is 70. -85, the hue (a value) is -3 to 3 and the hue (b value) is 10 to 16, the appearance of the paperboard is improved, and the surface layer, back layer, and intermediate layer A multilayer paperboard characterized by having a freeness of 350 to 450 cc and adjusting the air permeability of the paperboard to 10 to 150 seconds to obtain a crispy texture of the food. Has been.

  However, in the invention described in Patent Document 1, it is recommended to mix mechanical pulp of softwood (N material) such as radiata pine, Southern pine, Douglas fir in the middle layer of the multi-layered paper. In the invention described in, it is specified that TMP is used as mechanical pulp.

Japanese Patent No. 3714124 Japanese Patent No. 4302124

  The conventional multilayer paperboard or bulky paperboard is bulky, has a high cushioning property, has good printability as a paperboard for printing, and cannot satisfy all the effects of paper processing suitability as a paperboard board. Then, this invention makes it a subject to provide the bulky white paperboard which can satisfy | fill all these various effects, and its manufacturing method.

  By blending a specific bulk (specific volume) hardwood bleached chemi-thermomechanical pulp (L Bleached Chemi-Thermo Mechanical Pulp: hereinafter abbreviated as LBCTMP) into the middle layer of the bulky white paperboard, The present inventors have found that a bulky white paperboard having high bulkiness, high cushioning properties and good printability as a paperboard for printing, and good paper processing suitability as a paperboard board has been completed.

  That is, the invention according to claim 1 for solving the above-mentioned problem is a hardwood bleached chemo thermostat which is a multi-layered white board made of three or more layers and has a bulk of 3.0 to 3.8 cm 3 / g. Mechanical paper (LBCTMP) is a white paperboard characterized by blending 10 to 50% by weight of only the middle layer with respect to the whole pulp raw material of the middle layer, and combining the surface layer, middle layer and back layer. .

  In one embodiment, LBCTMP obtained from Maple genus is blended as the LBCTMP, and the density of white paperboard is 0.70 to 1.00 g / m2. Moreover, it has one or more coating layers containing a pigment and an adhesive on one side or both sides. In one embodiment, among the coating layers, the innermost coating layer in contact with the base paper contains calcium carbonate as a pigment, and contains 50 parts by weight or more of the calcium carbonate per 100 parts by weight of the pigment. Of the coating layers, the outermost coating layer contains a flat pigment, and the flat pigment contains 50 parts by weight or more per 100 parts by weight of the pigment.

  The invention according to claim 7 for solving the above-mentioned problem is a method for producing a multi-layered white paperboard comprising three or more layers, and a hardwood having a bulk of 3.0 to 3.8 cm <3> / g. Bleached chemi-thermomechanical pulp (LBCTMP) is blended only in the middle layer in an amount of 10 to 50% by weight based on the total pulp raw material in the middle layer, and the surface layer, the middle layer and the back layer are combined, and a method for producing white paperboard It is.

  In one embodiment, the present invention includes a step of providing one or more coating layers containing a pigment and an adhesive on one side or both sides of the white paperboard, and coating at least one of the coating layers with a blade coater. .

  The present invention is as described above. In the white paperboard according to the present invention, since LBCTMP is blended only in the middle layer, a decrease in surface strength is prevented, and paper powder derived from LBCTMP from the front and back surfaces of the paper. Therefore, there is no possibility that dirt is generated due to paper powder in the paper making process and the coating process, and there is an effect that white paperboard having good printability can be obtained.

  Also, because it is bulkier than conventional white paperboard, it is lighter than high-quality white paperboard of the same thickness, and has high cushioning properties suitable as whiteboard paper for printing on picture book covers / texts, catalogs, posters, brochures, calendars, etc. In addition, it is soft to the touch, and is not injured when an infant turns the page, and it is possible to obtain a safe white paperboard. Further, as a paperboard board, it has a high cushioning property and is suitable for molding processing. Has the effect of producing a good bulky white paperboard.

  The white paperboard according to the present invention is a multi-layered white paperboard composed of three or more layers, and LBCTMP having a bulk of 3.0 to 3.8 cm3 / g is contained only in the middle layer, in all raw materials of the middle layer. On the other hand, 10 to 50% by weight is blended, and the surface layer, middle layer and back layer are combined. The white paperboard according to the present invention is used as a base paper (hereinafter, sometimes referred to as “base paper” in this specification), and a coating layer containing a pigment and an adhesive on the base paper (hereinafter, referred to in this specification). , Sometimes referred to as “pigment coating layer”). This pigment coating layer has at least one layer on one side or both sides of the base paper.

  In the present invention, a pulp having a bulk of 3.0 to 3.8 cm 3 / g is blended in the middle layer of white paperboard, and the pulp is particularly limited as long as the bulk is in the above range. Although not, BCTMP is preferred, more preferably LBCTMP obtained from hardwood, most preferably LBCTMP obtained from the genus Maple. Among the broadleaf trees, the genus Maple has a bulk value suitable for the present invention. In the present invention, LBCTMP is an abbreviation for “L Bleached chemical thermomechanical pulp”, and is a pulp using L material made from hardwood among BCTMP, which is one kind of mechanical pulp. CTMP is a combination of TMP (Thermomechanical Pull) and chemical treatment, and BCTMP is a pulp bleached from CTMP. BCTMP is superior in flexibility and has good sheet density, tensile strength, and burst strength compared to TMP. In addition, CTMP has a feature that the pulp is bulky and opacity is high because the fiber form is flexible.

  And in order to obtain the bulky white board which intends in this invention, it is desirable that the bulk of LBCTMP is 3.0-3.8 cm <3> / g. The term “bulk” as used herein refers to a pulp made from hand-made paper according to JIS P8222: 1998, and the bulk of hand-made paper was measured according to ISO 534: 1988, and the bulk was 3.0 to 3.8 cm 3 / By using g LBCTMP, the desired bulky white paperboard density is obtained.

  In the white paperboard according to the present invention, the above bulk LBCTMP is blended only in the middle layer. In this way, the composition of LBCTMP is limited to only the middle layer. When LBCTMP is blended into the front layer and the back layer, the surface strength decreases, and paper powder derived from LBCTMP is generated from the front and back surfaces of the paper. This is because it causes stains in the paper making process and the coating process. In addition, printability tends to decrease due to a decrease in surface strength.

  In addition, the present inventors have found that when the BCTMP material to be blended in the middle layer is LBCTMP having hardwood pulp, the formation of the middle layer is better than when other BCTMPs are blended. The reason is presumed that the above-mentioned LBCTMP has better disintegration with a pulper than other BCTMPs. The formation is important for forming the layer structure. If the formation of the middle layer deteriorates, the overall formation also deteriorates. Also, the smoothness, printability, and molding processability of the surface layer and the back layer in contact with the middle layer. It is thought that it will adversely affect. In addition, the formation of the middle layer here refers to a surface layer and a back layer that are peeled off and the formation of the middle layer is visually observed.

  In the present invention, if the content of LBCTMP in the middle layer is too large, the density decreases greatly, and the printability and molding processability deteriorate. Therefore, 10 to 50% by weight (absolute dry weight) of the entire middle layer pulp It is possible to obtain a desired density by making the content preferably 20 to 40% by weight, more preferably 25 to 40% by weight. The density of the whole white paperboard is preferably 0.70 to 1.00 g / m2. In particular, when the pigment coating layer is not provided, it is preferably 0.70 to 0.74 g / m 2, and when the pigment coating layer is provided, 0.75 to 1.00 g / m 2 (preferably, 0.77 to 0.96 g / m2) is desirable.

  It does not specifically limit as pulp other than LBCTMP used by this invention, According to a use, it can select suitably. For example, virgin pulp such as N-BKP, L-BKP, mechanical pulp, etc. is used when used as printing paperboard and paper container food containers for relatively expensive picture book covers / texts, catalogs, posters, brochures, calendars, etc. can do. Moreover, when using for a food use, it is desirable to mix | blend a non-fluorescent pulp. In the case of food use, when recycled paper pulp is blended, quality and appearance including strength deteriorate, so it is desirable not to blend waste paper pulp.

  The raw material pulp used for paper layers other than the middle layer of the bulky white paperboard according to the present invention is not particularly limited, and a raw material pulp that is usually used can be used depending on the application. For example, NBKP or LBKP can be used. When NBKP is used, it is preferably 20% or less of the total dry weight of the pulp. The bulky white paperboard of the present invention consists of three or more layers, and the weight ratio of pulp between the middle layer and the other layers is preferably 33% to 50% by weight of the pulp weight of the whole layer. Is preferably a weight obtained by dividing the total weight of all layers by excluding the middle layer by the total number.

  You may mix | blend inorganic fillers, such as light calcium carbonate, heavy calcium carbonate, and talc, with the bulky white paperboard of this invention. Also, if necessary, for various paper making such as paper strength enhancer, internal sizing agent, retention agent, coagulant, sulfuric acid band, dye, antifoaming agent, UV protection agent, anti-fading agent, pitch control agent, etc. You may mix | blend a chemical | medical agent.

  An embodiment of the use of the white paperboard according to the present invention will be described. For example, when white paper having a pigment coating layer is used as a paper container, if the density of the white paperboard is less than 0.75 g / m2, the white paperboard itself The suitability of the process deteriorates. On the other hand, if the density exceeds 1.00 g / m 2, the white paperboard itself is hardened. For example, when folding is performed, the paper is cracked and the processability is deteriorated.

  When the white board according to the present invention is used as a printing white board, it is preferable to have a pigment coating layer on the base paper. When it has a pigment coating layer, if the density of white paperboard is less than 0.75 g / m <2>, the smoothness of a surface and a back surface will fall and printability will deteriorate. On the other hand, if the density exceeds 1.00 g / m 2, the paper becomes too hard and problems such as back cracks are likely to occur during printing and binding, which is not preferable.

  In the present invention, in order to adjust the density of the whole white paperboard, the beating freeness of the middle layer and the surface layer and the back layer containing LBCTMP is adjusted to 300 to 500 cc, and the basis weight ratio of the middle layer includes the surface layer, the middle layer and the back layer. The total basis weight (absolute dry weight) is adjusted to 10 to 60% by weight (preferably 20 to 50% by weight). The method according to the present invention can be applied to the case of four-layer or more multilayer papermaking in addition to the three-layer paperboard.

  In the present invention, the white paperboard is made with a multi-layered machine such as a long net, a circular net, or an ultraformer. The white paperboard in the present invention is bulky and cushioning compared to white paperboard not containing LBCTMP, and is excellent in printability and molding processability. Also, depending on the application and desired quality, by using the white paperboard of the present invention as a base paper and applying a coating liquid containing a pigment and an adhesive on one or both sides, a clearer printed matter and a good molding process It is preferable because aptitude can be obtained. The pigment coating layer is not particularly limited as long as it is one or more layers, but it is preferable to provide two or more layers in order to improve smoothness and whiteness.

  Although it does not specifically limit as a pigment used for the said pigment coating layer, The thing conventionally used for pigment coated paper can be used, for example, a kaolin, a clay, an engineered kaolin, a delaminated. Inorganic pigments such as clay, heavy calcium carbonate, light calcium carbonate, talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicate, colloidal silica, and satin white, and solid, hollow, or core-shell types Organic pigments such as can be used alone or in admixture of two or more as required.

  In the present invention, it is preferable to provide two or more pigment coating layers, and the undercoat layer preferably contains heavy calcium carbonate and / or light calcium carbonate in order to impart whiteness to the coating layer. . This is because the bulky coating layer structure scatters light efficiently. The content of light calcium carbonate, heavy calcium carbonate, or both is preferably 50 parts by weight or more, more preferably 70 parts by weight or more, and still more preferably 80 parts by weight or more per 100 parts by weight of the pigment.

  The topcoat layer preferably contains one or more flat pigments such as kaolin, clay, engineered kaolin, and delaminated clay in order to improve smoothness. The content of the flat pigment is preferably 50 parts by weight or more, more preferably 70 parts by weight or more per 100 parts by weight of the pigment.

  There is no restriction | limiting in particular about the adhesive agent (binder) used by this invention, The adhesive agent conventionally used for coated paper can be used. For example, as preferred adhesives, various copolymers such as styrene / butadiene, styrene / acrylic, ethylene / vinyl acetate, butadiene / methyl methacrylate, vinyl acetate / butyl acrylate, and polyvinyl alcohol and maleic anhydride copolymers. Synthetic adhesives such as acrylic acid / methyl methacrylate copolymer; Proteins such as casein, soybean protein, synthetic protein; Etherification of oxidized starch, positive starch, urea phosphated starch, hydroxyethyl etherified starch, etc. One or more ordinary adhesives for coated paper such as starches and starches such as dextrin; cellulose derivatives such as carboxymethylcellulose, hydroxyethylcellulose, and hydroxymethylcellulose can be appropriately selected and used.

  The amount of the adhesive in each coating layer used in the present invention is preferably 5 to 30 parts by weight, and 10 to 20 parts by weight with respect to 100 parts by weight of the pigment, from the viewpoint of printability and coating suitability. It is more preferable that

  The coating method is not particularly limited, and any coating machine that is usually used may be used. An on-machine coater or an off-machine coater may be used, and if it is an on-machine coater, a roll coater such as a size press coater or a gate roll coater, a blade coater, a blade metering size press coater, an air knife coater, or a curtain coater can be used. . In the present invention, it is preferable to apply one or more of the pigment coating layers with a blade coater in order to impart smoothness.

  The coating amount of the pigment coating solution is preferably 10 to 40 g / m 2, more preferably 10 to 20 g / m 2 in terms of dry weight per side. When there are a plurality of pigment coating layers, the coating amount is the total amount of each layer. When there are a plurality of pigment coating layers, the coating amount of each layer may be appropriately adjusted according to the application.

  The bulky white paperboard of the present invention may be subjected to a smoothing treatment in a surface treatment step or the like, if necessary, after papermaking or after a normal drying step and a coating layer on a base paper. In a preferred embodiment, it is finished by adjusting so that the water content of the bulky white paperboard after the paper making or by providing a pigment coating layer is 3 to 10% by weight, more preferably about 4 to 8% by weight. For smoothing processing, a smoothing processing device such as a normal super calendar, gloss calendar, soft calendar, thermal calendar, shoe calendar, or the like can be used. The smoothing apparatus is appropriately used on-machine or off-machine, and the form of the pressure device, the number of pressure nips, heating, and the like are also adjusted as appropriate.

  The bulky white paperboard of the present invention may also be coated with starch, polyacrylamide, polyvinyl alcohol, surface sizing agent, etc. within a range that does not impair the effects of the present invention using a known coater such as a size press coater or a gate roll coater. The pigment coating layer may be provided after coating these.

  The bulkiness of the bulky white paperboard according to the present invention is 90 to 600 g / m2, and generally about 150 to 450 g / m2. Since the bulky white paperboard of the present invention has a high paper thickness and is light, when used as printing paper, the overall weight of books, magazines and the like can be reduced. It is also suitable for writing paper such as notebooks. As a paper container, it can also be suitably used as a base paper for various molding sheets, a food paper container, or a cup noodle container or paper cup utilizing heat insulation.

  EXAMPLES Hereinafter, although this invention is further demonstrated based on an Example, it cannot be overemphasized that this invention is not limited to those Examples. Examples 1 to 6 (Table 1) and Comparative Examples 1 to 6 (Table 2) shown below are all three-layer papermaking. In addition, the numerical value which shows a mixing | blending is a numerical value based on the weight of solid content.

[Example 1]
<Base paper>
N-BKP 10%, L-BKP 90% (CSF 400cc), and the middle layer N-BKP 10%, L-BKP 80%, LBCTMP (manufactured by Tenbec, TEMCEL 400/80, bulk 3.4cm3) / G, Maple) 10%, the layers of Table 1 (basis weight ratio of each layer), each layer was subjected to a multi-layer paperboard machine, and the coating amount was 1 on both sides using a size press. Starch was applied so as to be ˜2 g / m 2 to obtain a base paper.
<Undercoating liquid>
After preparing a pigment slurry consisting of 100 parts by weight of heavy calcium carbonate (manufactured by PMMA Tech, FMT90-HS), 7 parts by weight of styrene-butadiene copolymer latex, phosphate esterified starch (Matsuya) with respect to 100 parts of pigment. Chemical Co., Neil Gum T55) (4.5 parts by weight) was added, and a water retention agent was added (0.08 parts by weight) to obtain an undercoat coating solution having a solid concentration of 62% by weight.
<Topcoat coating solution>
A pigment slurry consisting of 15 parts by weight of heavy calcium carbonate (Fimatec, FMT100), 57 parts by weight of fine kaolin (Caddam, Amazon Plus) and 28 parts by weight of engineered kaolin (Imeris, Capim DG) is prepared. After that, 16.5 parts by weight of styrene / butadiene copolymer latex and 2 parts by weight of phosphate esterified starch (manufactured by Matsutani Chemical Co., Ltd., Neil Gum T55) are added to 100 parts by weight of the pigment, and the solid content concentration is 50%. An overcoating liquid was obtained.
<Coating>
After forming the innermost coating layer by coating the undercoat coating solution on both sides of the base paper so that the solid content weight after drying is 7.5 g / m 2 per side using a blade coating device, After the drying process, using an air knife coating device, coat the top coating solution on both sides of the base paper so that the solid weight after drying is 7.5 g / m 2 per side. And a white paperboard having a basis weight of 190 g / m 2 was obtained.

[Example 2]
White paperboard in the same manner as in Example 1 except that N-BKP 10%, L-BKP 40%, LBCTMP (manufactured by Tenbec, TEMCEL 400/80, bulk 3.4 cm3 / g, Maple) 50% were used for the middle layer. Got.

[Example 3]
White paperboard in the same manner as in Example 1 except that N-BKP 10%, L-BKP 65%, LBCTMP (manufactured by Tenbec, TEMCEL400 / 80, bulk 3.4 cm3 / g, Maple) 25% Got.

[Example 4]
<Base paper>
N-BKP 10%, L-BKP 90% (CSF 425 cc) and the middle layer N-BKP 3%, L-BKP 57%, LBCTMP (manufactured by Tenbec, TEMCEL 400/80, bulk 3.4 cm3) / G, Maple) 40%, and with each layer ratio shown in Table 1, the layers are combined with a multilayer paperboard machine, and the coating amount on both sides is 1 to 2 g / m2 using a size press. Starch was applied to obtain a base paper.
<Coating>
Using the same undercoating liquid and topcoating liquid as in Example 1 and using a blade coating apparatus, the above-mentioned undercoating liquid was dried on both sides of the base paper at a solid content weight of 8 g / m 2 per side. After the coating process, the coating process is performed on the both sides of the base paper so that the solid content weight after drying is 8 g / m2 per side using the air knife coating device. Thus, a white paperboard having a basis weight of 248 g / m2 was obtained.

[Example 5]
A white paperboard with a basis weight of 242 g / m2 was obtained in the same manner as in Example 4 except that the back surface was not coated.

[Example 6]
A white paperboard having a basis weight of 223 g / m2 was obtained in the same manner as in Example 4 except that coating was not performed on both sides.

[Comparative Example 1]
Same as Example 1, except that N-BKP 10%, L-BKP 85%, LBCTMP (manufactured by Tenbec, TEMCEL 400/80, bulk 3.4 cm <3> / g, Maple) 5% were used. A white paperboard was obtained.

[Comparative Example 2]
A white paperboard was prepared in the same manner as in Example 1 except that L-BKP was 45% and LBCMP (Tembec, TEMEL400 / 80, bulk 3.4 cm3 / g, Maple) 55% was used for the middle layer of Example 1. Obtained.

[Comparative Example 3]
A white paperboard was obtained in the same manner as in Example 1 except that LBCTMP in Example 1 was changed to LBCTMP (manufactured by Tenbec, ASPEN325 / 85, bulk 2.3 cm3 / g).

[Comparative Example 4]
A white paperboard was obtained in the same manner as in Example 2 except that LBCTMP of Example 2 was changed to LBCTMP (manufactured by Tenbec, ASPEN325 / 85, bulk 2.3 cm3 / g).

[Comparative Example 5]
LBCTMP of Example 1 was changed to N / L mixed BCTMP (Miller Western Forest, Blended BCTMP, N material 25%, L material 75% mixed, bulk 2.4 cm3 / g). A white paperboard was obtained.

[Comparative Example 6]
A white paperboard was obtained in the same manner as in Example 1 except that LBCTMP of Example 1 was not blended at all and L-BKP was changed to 90%.

<Evaluation and test methods>
Basis weight: JIS P 8124: 2011
Thickness and density: JIS P 8118: 1998
Smoothness: JIS P 8155: 2010
Printability (table): Printed on the surface of bulky white paperboard using a Roland flat-print press (4 colors), and visually check the printing surface (fineness of printed matter, uneven unevenness of the printed matter, glossiness unevenness, etc.) Relative evaluation. The evaluation criteria are as follows.
○ = Good, △ = Slightly inferior, X = Inferior
Molding suitability: Comprehensive evaluation of ruled line cracking / breaking during molding into tray containers

<Table 1>

<Table 2>

  In Examples 1 to 6 shown in Table 1, which are within the scope of the matters specified in the claims of the present application, the printability (table) in each case where the basis weight is about 190 g / m 2 or about 240 g / m 2. Further, good evaluation was obtained with respect to suitability for molding process. In addition, Example 6 is an example in which the pigment coating layer is not provided, and although the result looks inferior to other examples and comparative examples in which the pigment coating layer is provided, the pigment coating layer is provided. A practically excellent level of evaluation was obtained as no white paperboard.

  On the other hand, Comparative Example 1 uses the same LBCTMP as Example 1, but the density of white paperboard increased because the blending ratio in the middle layer was as low as 5%, and the molding processability deteriorated. Similarly, Comparative Example 2 uses the same LBCTMP as in Example 1. However, since the blending ratio in the middle layer is as high as 55%, the formation of the middle layer is slightly deteriorated and the density of the white paperboard is low. The aptitude was inferior, and the molding process aptitude was slightly deteriorated.

  In Comparative Example 3, 10% of LBCTMP having a bulk of 2.3 cm <3> / g was blended. Since the bulk of LBCTMP was low, the density of white paperboard was increased and the molding processability was deteriorated. In Comparative Example 4, the same low LBCTMP having the same bulk as Comparative Example 3 was used and 50% of the middle layer was blended. Although the bulk became bulky, printability and moldability were slightly deteriorated.

  In Comparative Example 5, 10% N—L mixed BCTMP having a bulk of 2.4 cm 3 / g was blended, but the density of the white paperboard was high, the printability was slightly inferior, and the moldability was deteriorated.

  In Comparative Example 6, since LBCTMP was not blended at all in the middle layer, the density of white paperboard was high, the printability was slightly inferior, and the moldability was deteriorated.

[0003]
o Mechanical Pulp (hereinafter sometimes abbreviated as LBCTMP), it is bulky, has high cushioning properties, has good printability as a paperboard for printing, and has high paperworkability as a paperboard board. And the present invention has been completed.
[0010]
That is, the invention according to claim 1 for solving the above-mentioned problem is a hardwood bleached chemo thermostat which is a multi-layered white board made of three or more layers and has a bulk of 3.0 to 3.8 cm 3 / g. Mechanical paper (LBCTMP) is a white paperboard characterized by blending 10 to 50% by weight of only the middle layer with respect to the whole pulp raw material of the middle layer, and combining the surface layer, middle layer and back layer. .
[0011]
In one embodiment, LBCTMP obtained from Maple genus is blended as the LBCTMP, and the density of white paperboard is 0.70 to 1.00 g / cm3. Moreover, it has one or more coating layers containing a pigment and an adhesive on one side or both sides. In one embodiment, among the coating layers, the innermost coating layer in contact with the base paper contains calcium carbonate as a pigment, and contains 50 parts by weight or more of the calcium carbonate per 100 parts by weight of the pigment. Of the coating layers, the outermost coating layer contains a flat pigment, and the flat pigment contains 50 parts by weight or more per 100 parts by weight of the pigment.
[0012]
The invention according to claim 7 for solving the above-mentioned problem is a method for producing a multi-layered white paperboard comprising three or more layers, and a hardwood having a bulk of 3.0 to 3.8 cm <3> / g. Bleached chemi-thermomechanical pulp (LBCTMP) is blended only in the middle layer in an amount of 10 to 50% by weight based on the total pulp raw material in the middle layer, and the surface layer, the middle layer and the back layer are combined, and a method for producing white paperboard It is.
[0013]
In one embodiment, the present invention includes a step of providing one or more coating layers containing a pigment and an adhesive on one side or both sides of the white paperboard, and coating at least one of the coating layers with a blade coater. .
Effect of the Invention [0014]
The present invention is as described above, and in the white paperboard according to the present invention, since LBCTMP is blended only in the middle layer, a decrease in surface strength is prevented,

[0006]
By making the amount%, more preferably 25 to 40% by weight, a desired density can be obtained. The density of the whole white paperboard is preferably 0.70 to 1.00 g / cm3. In particular, when it does not have a pigment coating layer, it is desirably 0.70 to 0.74 g / cm 3, and when it has a pigment coating layer, 0.75 to 1.00 g / cm 3 (preferably, 0.77 to 0.96 g / cm3) is desirable.
[0022]
It does not specifically limit as pulp other than LBCTMP used by this invention, According to a use, it can select suitably. For example, virgin pulp such as N-BKP, L-BKP, and mechanical pulp is used when used as printing paperboard and paper container for relatively expensive picture book covers / text, catalogs, posters, brochures, calendars, etc. can do. Moreover, when using for a food use, it is desirable to mix | blend a non-fluorescent pulp. In the case of food use, when recycled paper pulp is blended, quality and appearance including strength deteriorate, so it is desirable not to blend waste paper pulp.
[0023]
The raw material pulp used for paper layers other than the middle layer of the bulky white paperboard according to the present invention is not particularly limited, and a raw material pulp that is usually used can be used depending on the application. For example, NBKP or LBKP can be used. When NBKP is used, it is preferably 20% or less of the total dry weight of the pulp. The bulky white paperboard of the present invention consists of three or more layers, and the weight ratio of pulp between the middle layer and the other layers is preferably 33% to 50% by weight of the pulp weight of the whole layer. Is preferably a weight obtained by dividing the total weight of all layers by excluding the middle layer by the total number.
[0024]
You may mix | blend inorganic fillers, such as light calcium carbonate, heavy calcium carbonate, and talc, with the bulky white paperboard of this invention. Also, if necessary, for various paper making such as paper strength enhancer, internal sizing agent, retention agent, coagulant, sulfuric acid band, dye, antifoaming agent, UV protection agent, anti-fading agent, pitch control agent, etc. You may mix | blend a chemical | medical agent.
[0025]
One embodiment of the use of the white paperboard according to the present invention is, for example, a pigment.

[0007]
When white paperboard having a coating layer is used as a paper container, if the density of the white paperboard is less than 0.75 g / cm3, the whiteboard paper itself is lost and processing suitability deteriorates. On the other hand, when the density exceeds 1.00 g / cm 3, the white paperboard itself is hardened. For example, when folding is performed, the paper is cracked and the processability is deteriorated.
[0026]
When the white board according to the present invention is used as a printing white board, it is preferable to have a pigment coating layer on the base paper. In the case of having a pigment coating layer, if the density of the white paperboard is less than 0.75 g / cm3, the smoothness of the front surface and the back surface is lowered and the printability is deteriorated. On the other hand, if the density exceeds 1.00 g / cm 3, the paper becomes too hard and problems such as back cracks are liable to occur at the time of bookbinding.
[0027]
In the present invention, in order to adjust the density of the whole white paperboard, the beating freeness of the middle layer and the surface layer and the back layer containing LBCTMP is adjusted to 300 to 500 cc, and the basis weight ratio of the middle layer includes the surface layer, the middle layer and the back layer. The total basis weight (absolute dry weight) is adjusted to 10 to 60% by weight (preferably 20 to 50% by weight). The method according to the present invention can be applied to the case of four-layer or more multilayer papermaking in addition to the three-layer paperboard.
[0028]
In the present invention, the white paperboard is made with a multi-layered machine such as a long net, a circular net, or an ultraformer. The white paperboard in the present invention is bulky and cushioning compared to white paperboard not containing LBCTMP, and is excellent in printability and molding processability. Also, depending on the application and desired quality, by using the white paperboard of the present invention as a base paper and applying a coating liquid containing a pigment and an adhesive on one or both sides, a clearer printed matter and a good molding process It is preferable because aptitude can be obtained. The pigment coating layer is not particularly limited as long as it is one or more layers, but it is preferable to provide two or more layers in order to improve smoothness and whiteness.
[0029]
Although it does not specifically limit as a pigment used for the said pigment coating layer, The thing conventionally used for pigment coated paper can be used, for example, a kaolin, a clay, an engineered kaolin, a delaminated. Clay, heavy calcium carbonate, light calcium carbonate, talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicate, colloidal silica, satin

Claims (9)

  White board made of multi-layered paper consisting of 3 or more layers, and hardwood bleached chemi-thermomechanical pulp (LBCTMP) with a bulk of 3.0 to 3.8 cm 3 / g is applied only to the middle layer, to all pulp raw materials of the middle layer A white paperboard containing 10 to 50% by weight of the surface layer, middle layer and back layer.   The white paperboard of Claim 1 which mix | blends LBCTMP obtained from Maple genus as said LBCTMP.   The white paperboard of Claim 1 or 2 whose density is 0.70-1.00 g / m2.   The white paperboard in any one of Claims 1-3 which has one or more coating layers containing a pigment and an adhesive agent in the single side | surface or both surfaces of the said white paperboard.   5. The white paperboard according to claim 4, wherein the innermost coating layer in contact with the base paper among the coating layers contains calcium carbonate as a pigment, and contains 50 parts by weight or more of the calcium carbonate per 100 parts by weight of the pigment.   6. The white paperboard according to claim 4, wherein, among the coating layers, the outermost coating layer contains a flat pigment, and the flat pigment is contained in an amount of 50 parts by weight or more per 100 parts by weight of the pigment.   A method for producing multi-layered white paperboard comprising three or more layers, wherein hardwood bleached chemithermomechanical pulp (LBCTMP) having a bulk of 3.0 to 3.8 cm3 / g is applied to only the middle layer, all of the middle layer A method for producing white paperboard, comprising blending 10 to 50% by weight with respect to a pulp raw material, and combining a surface layer, an intermediate layer and a back layer.   8. The method for producing white paperboard according to claim 7, wherein one or more coating layers containing a pigment and an adhesive are provided on one or both surfaces of the white paperboard.   The manufacturing method of the white paperboard of Claim 8 including the process of coating at least 1 layer with the blade coater among the said coating layers.