JP2005281939A - Paperboard - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paperboard stably imparting a feeling such as Japanese paper with slight defects by making conflicting conditions such as regulation of knot size compatible and removal of foreign materials contained in pulp compatible with each other. <P>SOLUTION: The paperboard has a single paper ply is obtained by blending knots in raw material pulp of the paperboard. The knots have ≥0.70 mm<SP>2</SP>to ≤2.0 mm<SP>2</SP>size of the maximum knots based on J. TAPPI-No. 43. The paper surface of the paperboard has 50-500 mm<SP>2</SP>/m<SP>2</SP>area ratio of the knots based on the J. TAPPI-No. 43. The paper surface of the paperboard has ≥5 mm<SP>2</SP>/m<SP>2</SP>area ratio of the knots having ≥0.50 mm<SP>2</SP>size based on the J. TAPPI-No. 43. In the paperboard having two or more paper plies of at least the skim and the back, the knots are blended in the raw material pulp of the skim and/or back. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a paperboard using pulp mixed with knots at least on its surface.

In general, in the manufacture of pulp for papermaking, the raw material wood chips are obtained by replacing the air contained therein with water vapor and then using an alkaline liquid (for example, a mixed solution of caustic soda and sodium sulfide in a weight ratio of 8: 2 in the sulfate method, In the soda method, caustic soda alone) is added to the digester and heated in this digester to dissolve the lignin in the wood to unbleached pulp, and then washed with water, and the alkali containing the dissolved lignin Remove the liquid. Next, lump knots (sections) are separated by a knotter, and after passing through several screens to remove coarse materials as screen troughs, they are sent to the subsequent washing step and O ₂ delignification step.

  Since the knots separated by the knotter contain pulp fibers at a high rate, conventionally, as shown in Patent Document 1, for example, the knots are collected and returned to the raw material supply side by a pump as a dispersion, and the raw material wood The pulp fiber is taken out by mixing in the chip and re-cooking. In addition, the knot may be disposed of as a bag.

  However, in recent years, a paperboard having a unique texture of knots, that is, a texture like Japanese paper that cannot be imparted by printing, has been commercialized by mixing the above knots with raw pulp and making paper.

  However, since knots are larger than pulp fibers and contain large binding fibers, the problem of screen clogging tends to occur when paper is made in a normal production flow. Therefore, the pulp mixed with the knots bypasses the screen or passes through the screen process without being screened by removing the screen basket. However, if the knot-mixed pulp is not subjected to a screen treatment, it is impossible to remove coarse foreign matters such as bundled fibers present in the stock and fiber lump caused by entanglement. Accordingly, there is a problem that defects due to these foreign matters are likely to occur on the paperboard, and the productivity of the paperboard is significantly reduced.

  Therefore, in order to screen the pulp mixed with the knots, the knots are finely divided with a disintegrator, a beater, etc., then mixed with the raw material pulp, and paper making, the foreign matters as described above are removed, and defects due to the foreign matters Although the knots are too fine, even if the knots are mixed with the pulp, the unique texture of the knots cannot be imparted to the paperboard. There is a problem that the meaning of mixing knots is diminished because it cannot be applied.

As described above, when knots are untreated and mixed with pulp, the knot has a unique texture, that is, a paper-like texture can be imparted to the paperboard, but the screen treatment can be performed. In other words, the paperboard has a defect that defects are likely to occur. On the other hand, when the knot is refined with a disintegrator, a beater, etc., and then mixed with pulp, it can be screened, so it has the advantage of reducing paperboard defects, but the knot has a unique texture In other words, it has the disadvantage that a texture like Japanese paper cannot be imparted to the paperboard. In other words, the contradictory conditions of adjusting the size of the knot and the removal of foreign matter contained in the pulp cannot be achieved at the same time. It was impossible to achieve both of reducing defects.
Japanese Patent No. 2746046

  The present invention has been made in view of the above-described circumstances, and the purpose of the present invention is to achieve both the adjustment of the size of the knot and the conflicting conditions of the removal of foreign matter contained in the pulp, It is to provide a paperboard which can stably impart a texture like Japanese paper and has few defects.

  The above object of the present invention is achieved by providing a paperboard having a single paper layer, wherein knots are mixed with the raw pulp of the paperboard.

  The object of the present invention is to provide a paperboard comprising knots mixed with raw pulp of the surface layer and / or the back layer in a paperboard having at least two paper layers of a surface layer and a back layer. Is achieved by

The above object of the present invention is to provide the knot according to J.A. TAPPI-No. The maximum knot size based on 43 is effectively achieved by providing a paperboard characterized in that it is 0.70 mm ² or more and 2.0 mm ² or less.

Further, the object of the present invention is that the paper surface of the paperboard is J.P. TAPPI-No. This is achieved more effectively by providing a paperboard characterized in that the knot area ratio based on 43 is 50-500 mm ² / m ² .

Furthermore, the object of the present invention is to provide a paper surface of the paperboard as described in J. TAPPI-No. The area ratio of the knots having a size of 0.50 mm ² or more based on No. 43 is 5 mm ² / m ² or more.

  According to the paperboard according to the present invention, a texture like Japanese paper that cannot be imparted by printing can be imparted by mixing knots with raw pulp.

In addition, since the knot having the maximum knot size of 0.70 mm ² or more and 2.0 mm ² or less was mixed, both the adjustment of the knot size and the conflicting conditions of removing foreign substances contained in the pulp are compatible. Can be made. Therefore, it is possible to stably impart a texture like Japanese paper to the paperboard, and screen processing can be performed on the pulp mixed with knots, thereby reducing defects caused by foreign matter on the paperboard and increasing the productivity of the paperboard. Can be improved. Furthermore, since the knots are adjusted to an appropriate size, the knot yield can be improved, and the paperboard can be manufactured at low cost.

Moreover, since the knots were mixed so that the knot area ratio of the paper surface of the paperboard was 50 to 500 mm ² / m ² , the contradictory conditions of adjusting the size of the knots and removing foreign substances contained in the pulp were more Both can be achieved. Therefore, a texture like Japanese paper can be more stably imparted to the paperboard, and screen processing can be applied to the pulp mixed with knots, thereby reducing defects caused by foreign matter on the paperboard and increasing the productivity of the paperboard. Can be improved. Furthermore, since the knots are adjusted to an appropriate size, the knot yield can be improved, and the paperboard can be manufactured at low cost.

Furthermore, since the area ratio of knots having a size of 0.50 mm ² or more is 5 mm ² / m ² or more, the paper surface of the paper board can be further imparted with a texture like Japanese paper.

  Hereinafter, the paperboard having a single paper layer according to the present invention will be described in detail.

  The raw material pulp used for the base paper of the paperboard according to the present invention is mixed with knots. By mixing knots with raw material pulp and making paper, it is possible to impart a texture like Japanese paper that cannot be imparted by printing to a paperboard having a simple texture.

  Raw pulp such as bleached pulp such as softwood bleached kraft pulp (NBKP) and hardwood bleached kraft pulp (LBKP), unbleached pulp such as softwood unbleached kraft pulp (NUKP) and hardwood unbleached kraft pulp (LUKP) Various known raw material pulps such as deinked pulp, waste paper pulp, or known non-wood pulp such as kenaf, bamboo, hemp, and straw can be used, but bleached pulp is used as the raw material pulp for the base paper In this case, the contrast between the texture of the knot and the color tone of the paperboard becomes strong, and the texture of the knot can be further enhanced, which is preferable.

  Furthermore, by coloring the raw pulp mixed with knots, it is possible to soften the visual sense, give a calm impression, and bring out a warm color tone. In other words, a paperboard having a simple texture can be produced.

Knot TAPPI-No. Measured as the amount of contaminants based on 43 (contamination test method by image analysis), various known disintegrators and beatings so that the maximum knot size is 0.70 mm ^{2 to} 2.0 mm ² It is made fine with a pulverizer or pulverizer. By using knots with the maximum knot size, it is possible to stably impart a texture like Japanese paper to paperboard, and depending on the purpose of use and needs, the variety of paper A different texture can be given. In addition, the beating time in the disaggregator or the like can be appropriately adjusted depending on the type of paper.

Further, when the maximum knot size is within the above range, the conflicting conditions of adjusting the knot size and removing foreign substances contained in the pulp can be achieved. Therefore, it is possible to stably impart a texture like Japanese paper to the paperboard, and screen processing can be performed on the pulp mixed with knots, thereby reducing defects caused by foreign matter on the paperboard and increasing the productivity of the paperboard. Can be improved. Furthermore, since the knots are adjusted to an appropriate size, the amount of screen rejection is reduced, that is, the yield of knots is improved, so that paperboard can be manufactured at low cost. If the maximum knot size is less than 0.70 mm ² , the knot-mixed pulp can be screened, thereby reducing defects caused by foreign matter on the paperboard and improving the paperboard productivity. Although the knot is too fine, the paperboard cannot be given a texture like Japanese paper. On the other hand, if the maximum knot size is larger than 2.0 mm ² , a texture like Japanese paper can be stably imparted to the paperboard, but the knot-mixed pulp cannot be screened. In addition, defects due to foreign matters are likely to occur on the paperboard, and the productivity of the paperboard is reduced and the yield of knots is also reduced.

  Furthermore, since screen processing is performed on the pulp mixed with knots, foreign matter can be prevented from entering the paper making process, so that defects caused by foreign matter on the paperboard can be further reduced, and the productivity of the paperboard can be reduced. It can be improved further.

  Note that the size of the knot need not be uniform as long as the above-described conditions are satisfied, and the shape of the knot need not be a specific shape. If the knots are not uniform in size and shape, the paperboard can be given a more texture like Japanese paper.

  The amount of knots in the present invention is 0.5 to 5% by weight, more preferably 1.5 to 4% by weight, based on the raw material pulp. Thus, by adjusting the size of the knot and the blending amount with respect to the raw material pulp, it is possible to produce a paperboard mixed with knots having a good texture at low cost. When the knot content is less than 0.5% by weight, a texture like Japanese paper cannot be stably imparted to the paperboard. On the other hand, if it exceeds 5% by weight, a paper-like texture can be imparted to the paperboard, but the fiber-to-fiber bond of the pulp is weakened by the knots, so the paper strength of the paperboard is reduced.

  In addition, it is more preferable to mix knots with a dedicated addition line because the knot mixing amount can be adjusted in a short time.

  In addition, since the amount of knots can be finely adjusted by adjusting the screen reject amount, the present paperboard can be given a texture like Japanese paper more stably.

The paper surface of the paperboard according to the present invention is J.P. TAPPI-No. Knot area ratio of which is based on 43 so that the range of 50~500mm ² / ^{m 2,} adjusted by the reject of the screen. When the area ratio of the knots on the paper surface of the present paperboard is within such a range, the conflicting conditions of adjusting the size of the knots and removing foreign substances contained in the pulp can be achieved. Therefore, the texture of Japanese paper can be more stably applied to the paperboard, and the screen processing can be applied to the pulp mixed with the knots, so that the defects due to the foreign matter of the paperboard are further reduced, and the production of the paperboard The sex can be further improved. Furthermore, since the knots are adjusted to an appropriate size, the knot yield can be further improved, and the paperboard can be manufactured at a low cost. When the knot area ratio of the paper surface of the paperboard is 50 mm ² / m ² or less, since the knot content is small, a texture like Japanese paper cannot be imparted to the paperboard. On the other hand, if the knot area ratio of the paper surface of the paperboard exceeds 500 mm ² / m ² , screen processing cannot be performed, and the productivity of the paperboard is reduced, the yield of the knots is reduced, and furthermore, the paperboard This causes problems such as a decrease in paper strength.

Furthermore, the paper surface of the paperboard according to the present invention is J.P. TAPPI-No. The area ratio of knots having a size of 0.50 mm ² or more based on 43 is 5 mm ² / m ² or more. If the knot size is 0.50 mm ² or more, the knot can be visually observed. If the knot area ratio is 5 mm ² / m ² or more in this way, the paperboard is made of Japanese paper. Such a texture can be further imparted.

  The knots as described above can be mixed with the raw material pulp without any problem by a known papermaking method.

  In addition to the knots described above, sizing agents such as internal sizing agents, neutral sizing agents, polymer sizing agents, acidic sizing agents, and fillers may be added to the raw material pulp of the paperboard according to the present invention. . In addition, filler dispersants, thickeners, fluidity improvers, antifoaming agents, antifoaming agents, mold release agents, foaming agents, penetrating agents, coloring dyes, coloring pigments, fluorescent whitening agents, UV absorbers, Various known additives such as antioxidants, antiseptics, antibacterial agents, and water resistance agents may be added.

  Further, the papermaking method is not particularly limited, and either an acidic papermaking method or a neutral papermaking method may be used. As the paper machine, various known paper machines such as a long net paper machine, a twin wire paper machine, a circular net paper machine, and a short net network machine can be used.

The basis weight of the base paper of the paperboard according to the present invention is not particularly limited, and the basic weight of a general paperboard, specifically 30 to 500 g / m ² , more preferably 50 to 300 g / m ^2. it can.

  Note that the paper layer of the base paper of the present paperboard may be a single layer as described above, or may be a plurality of layers having at least two paper layers of a front layer and a back layer. In the case where the paper layer of the base paper is composed of a plurality of layers, if the knots as described above are mixed with at least the raw material pulp used for the base paper of the front layer and / or the back layer, the intended effect of the present invention can be obtained. be able to.

  In order to confirm the effect of the paperboard according to the present invention, various samples as described below were prepared and a test for evaluating the quality of each sample was performed. In addition, this invention is not restrict | limited by this Example.

  Seven types of paperboards according to the present invention (referred to as “Sample 1” through “Sample 7”) and eight types of paperboard for comparison with these Samples 1 through 7 (referred to as “Comparative Sample 1”) Or “Comparative Sample 8”).

The paperboard according to each sample and comparative sample in this example is a 6-layer paperboard having a surface layer, four middle layers, and a back layer, and a total basis weight of 280 g / m ² . As the raw material pulp of each paper layer, a mixed paper stock of 20 parts by weight of softwood bleached kraft pulp (freeness 500 ml) and 80 parts by weight of hardwood bleached kraft pulp (freeness 400 ml) was used. In addition, in the raw material pulp of the surface layer, knots are blended in the above mixed paper stock in the blending amount shown in Table 1, and in the raw material pulp of 2 to 6 layers, that is, the raw material pulp of 4 layers of the middle layer and the back layer, Use the mixed paper as it is without blending knots.

  Moreover, the knot disaggregation time blended with the raw material pulp of the surface layer was as shown in Table 1, and the area ratio of knots on the paper surface of the paperboard was adjusted by the reject amount of the screen. Table 1 shows the results of evaluating the texture, the number of defects, and the knot yield for all of these samples and the comparative sample.

  The “texture” in Table 1 is a visual evaluation of the texture of the obtained paperboard. The evaluation criteria are “very good” marked with ◎, “good” marked with ○, and “bad” marked with “×”. ”.

The “number of defects” is an evaluation of the total number of foreign matters having a diameter of 5 mm or more and holes having a diameter of 1 mm or more generated per 10000 m ^{2 of} paperboard, and is automatically detected by a defect detector installed in the paper machine. It is detected. The evaluation criteria were divided into four levels: “2 or less” marked with ◎, “3 to 5” marked with ◯, “6 to 9” marked with Δ, and “10 or more” marked with ×.

  “Knot yield” refers to sampling of screen processing rejects, making handsheets, and comparing the amount of knots removed on the screen. 3 levels, “small”, “small” with ○, and “large” with x.

表１から、試料１ないし試料７、すなわち本発明に係る板紙であると、風合い、欠陥数、及びノットの歩留りが良好な結果になることが分かる。すなわち、本発明に係る板紙であると、板紙に和紙のような風合いを付与することができると共に、板紙の異物による欠陥を減少させることができることが分かる。また、ノットの歩留りを向上させることができることも分かる。

From Table 1, it can be seen that Samples 1 to 7, that is, the paperboard according to the present invention, have favorable results in texture, number of defects, and knot yield. That is, it can be seen that the paperboard according to the present invention can give the paperboard a texture like Japanese paper and can reduce defects due to foreign matter on the paperboard. It can also be seen that the knot yield can be improved.

Claims (5)

  A paperboard having a single paper layer, wherein knots are mixed with the raw pulp of the paperboard.   A paperboard having at least two paper layers, ie, a surface layer and a back layer, wherein knots are mixed with the raw material pulp of the surface layer and / or the back layer. The knot is described in J. Org. TAPPI-No. The paperboard according to claim 1 or ² , wherein the size of the maximum knot based on 43 is 0.70 mm ² or more and 2.0 mm ² or less. The paper surface of the paperboard is J.P. TAPPI-No. Paperboard according to any one of claims 1 to 3 knots area ratio of which is based on 43 characterized in that it is a 50~500mm ² / ^{m 2.} The paper surface of the paperboard is J.P. TAPPI-No. 5. The paperboard according to claim 1, wherein an area ratio of the knots having a size of 0.50 mm ² or more based on No. 43 is 5 mm ² / m ² or more.