JPH10259587A - Multiply paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sheet of multiply paper excellent in smoothness and stiffness by composing the outermost ply of a paper stock prepared by treating a kraft pulp after beating with an enzyme having cellulolytic activities. SOLUTION: This sheet of multiply paper of three or more plies obtained by carrying out the beating treatment of a kraft pulp, then treating the beaten kraft pulp with an enzyme having cellulolytic activities such as endo-β-1, preparing a paper stock for the outermost ply of the paper having a multiply structure and conducting the combination of the paper stock for the outermost ply so as to provide a weight ratio of the outermost ply to the whole paper within the range of 20-70wt.% expressed in terms of bone-dry weight ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper having a multilayer structure. In particular, the present invention relates to paper that can be used as high-quality paper, printing paper, coating base paper, information recording paper base paper, or the like having a multilayer structure with excellent smoothness and rigidity.

[0002]

2. Description of the Related Art In recent years, paper has been reduced in weight in terms of resource saving and physical distribution. However, when the weight of the paper is reduced, there is a problem that the rigidity of the paper is reduced. Therefore, paper having high rigidity is demanded. Since the stiffness of paper is governed by the elastic modulus and thickness of the paper, the type of pulp fiber used to increase the elastic modulus of the paper and increase the thickness of the paper to make the paper bulky,
Various conditions for beating, preparation, papermaking, finishing, etc. are used to respond.

[0003] As a method of increasing the elastic modulus of the paper, heavy beating of the pulp fiber used to reduce the freeness of the pulp,
It is known to increase a press linear pressure in a press part. The fiber wall of the heavily beaten pulp is fibrillated, and when paper is produced using this pulp, the inter-fiber bonding area increases and the elastic modulus of the paper improves. Further, by increasing the press linear pressure, the density increases and the elastic modulus of the paper increases. However, these methods of increasing the modulus of elasticity increase the density, in other words, decrease the paper thickness, and do not necessarily increase the rigidity.

On the other hand, as a method of increasing the paper thickness, a method of using a hard pulp material such as mechanical pulp alone or in combination with a chemical pulp from a raw material side, a method using a lightly beaten chemical pulp, a method using a chemical or A method using a physically treated pulp raw material has been studied, and the technology has been widely disclosed. For example, (1) a cellulosic material typified by wood pulp is used as a binder in the form of fine fibers, and is blended with a stock made of unbeaten or lightly beaten fibers (JP-A-58-24000). ), (2) a mixture of a pulp fiber subjected to a cross-linking treatment and a heat-sealing fiber (JP-A-3-14700, JP-A-3-130499, JP-A-4-202895), and (3) pulp. There are known those obtained by treating fibers with a cellulose-decomposing enzyme (Japanese Patent Application Laid-Open No. 148794/1993), and those containing (4) pulp fibers partially mercerized (Japanese Patent Application Laid-Open No. 7-189168). However, although the paper obtained by these methods is thicker than the paper obtained by the conventional method, the effect of improving the stiffness is not at a satisfactory level and the surface smoothness is also satisfactory. Not something you can do.

[0005] In the papermaking process, methods for improving the rigidity in terms of equipment and operation include the degree of vacuum of the suction roll of the press part of a wet paper machine, the difference in surface temperature between the lower and upper dryer cylinders of the dry part, and the nip of the calendar part. It is known to increase the paper thickness by adjusting the number or the nip pressure. Although the paper thickness can be increased by these methods, the bonding area between fibers decreases, and the elasticity of the paper decreases due to the decrease in density, and the rigidity is not necessarily improved. In addition, the strength and the smoothness of the paper surface are greatly reduced, and are not suitable for uses such as high-quality paper, base paper for information recording paper, and printing paper.

[0006] Increasing the elastic modulus and increasing the paper thickness are inconsistent with the quality of the paper, and the problem has not yet been solved.

[0007] Multi-layer papermaking is mainly used as a paperboard manufacturing technique, and is generally performed using a circular net making machine, a fourdrinier making machine or the like. Paperboard is
Normally, the surface is composed of a surface layer composed of high-quality pulp such as chemical pulp used for printing, etc., and one or more inner layers such as a lower layer, a middle layer, and a back layer containing a lot of waste paper pulp and the like having lower quality than the surface layer .

The purpose is to make up for the drawback that the appearance of the paperboard is impaired due to the use of pulp made from waste paper and the drawback that the strength is low. By providing a surface layer, the whiteness and smoothness of the paperboard are improved. In addition, since the generation of paper dust and the like is reduced, the appearance of the paperboard can be improved, and the influence of foreign matter on the running property can be minimized.

JP-A-6-128891 discloses that the ratio of xylanase activity / CM-cellulase activity is 0.05 to 10 after beating or before beating pulp containing waste paper.
It is disclosed that the stiffness can be improved by treating with an enzyme in the range described above and using it as a back layer of paperboard. However, this technology is a technology in the paperboard field,
Although the elasticity of the paper is improved by the enzymatic treatment, when the treated pulp contains waste paper, the density is reduced, so that it can be applied only to the back layer having a small thickness in the total thickness of the paperboard.

In recent years, a multi-layer head box, which is a multi-layer head box, has been developed and put into practical use, and is used for multi-layer papermaking. This technology is mainly used for household paper such as tissues and paper towels, and uses virgin pulp to produce excellent quality paper by multilayering technology. For example, in the case of two layers, hardwood pulp is used for the surface layer to provide smoothness and flexibility, and softwood pulp having superior strength and absorbency is used for the inner layer.

Japanese Patent Application Laid-Open No. 3-180599 discloses that pulp having a lower CSF value than that of an inner layer is formed on both sides of an inner layer made of 100% chemical pulp as a raw material and pulp having a high CSF (Canadian standard freeness). A recording paper comprising an outer layer as a raw material is disclosed. However, in order to obtain a sufficient stiffness improving effect, it is necessary to use pulp that has been beaten to a surface layer of CSF 350 ml or less, which causes problems in operability such as dehydration and drying during production, Becomes hard and excellent surface smoothness cannot be obtained.

[0012]

In view of this situation, the present inventors have conducted various studies on the relationship between the paper layer structure and the smoothness and rigidity. As a result, the paper has a multilayer structure and the pulp used for the surface layer It was found that a paper having both excellent smoothness and rigidity could be obtained by specifying, and the present invention was completed. An object of the present invention is to provide a paper that can be used as a high-quality paper, a base paper for information recording paper, a printing paper, etc. having a multilayer structure excellent in smoothness and rigidity.

[0013]

The present invention is a multilayer paper having three or more layers, which has an outermost layer composed of a chemical pulp treated with an enzyme having cellulolytic activity after beating treatment.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the pulp used for the outermost layer is a raw pulp made of hardwood wood or softwood wood, which is obtained by a cooking method such as kraft cooking, sulfite cooking, soda cooking, polysulfide cooking, or the like. It is a bleached chemical pulp which has been bleached by a publicly-available multi-stage bleaching treatment without or with oxygen delignification of the bleached chemical pulp. Although the whiteness of the pulp after bleaching is not particularly limited, it is 80% in view of the appearance of paper.
(ISO whiteness) or more is preferable.

At the time of use of this pulp, first, a known and publicly used beating equipment, for example, a disc refiner, a beater, a conical refiner or the like is used, and the pulp is beaten. The degree of beating differs depending on the type and condition of the pulp used for the layer in contact with the outermost layer and the inner layer,
In consideration of the efficiency in the enzymatic treatment in the next step, the range of 350 to 450 mL in terms of Canadian standard freeness (hereinafter abbreviated as CSF) is preferable.

Next, the beaten pulp is treated with an enzyme having cellulolytic activity. The enzyme having cellulose-decomposing activity added in the present invention must include at least an enzyme that degrades cellulose chains in pulp fibers. Examples of such enzymes include endo-β-1,4-glucanase, β-D glucosidase, exo-β-1,4-D glucosidase, exocellobiohydrolase, and the like. One or more of these can be used as appropriate. Of course, enzymes other than those described above can be used as long as they degrade cellulose chains. In addition, the origin of the enzyme may be derived from mold or bacteria, and is not particularly limited.

The difference between the CSF value of the pulp after the enzyme treatment and the CSF value before the enzyme treatment is 5 degrees.
It is important to adjust to 0-150 mL. By the way,
When the amount is less than 50 mL, the degree of the enzyme treatment is not sufficient, and the effect of improving drainage is small. On the other hand, when the amount is 150 mL or more, the effect of the enzyme treatment is too large, and the strength of the pulp is impaired.

Regarding the method of enzymatic treatment of pulp, as described above, the difference between the CSF values before and after the enzymatic treatment is 50 to 150.
Any method may be used as long as the condition is mL, and there is no particular limitation. For example, a short-time treatment using an enzyme having high cellulase-degrading activity, a long-term treatment using an enzyme having low cellulase-degrading activity, or a non-optimal condition even if the treatment is carried out for a short time under the optimal conditions of the enzyme Even if the treatment is performed for a long time under the conditions, the condition can be appropriately adopted as long as the difference in the CSF value before and after the enzyme treatment is 50 to 150 mL, such as repeating the enzyme treatment a plurality of times. However, in consideration of economy, processing efficiency, etc., the optimum pH is 3 to 11 and the optimum temperature is 10 to 10.
Existing tanks, chests, with enzymes at ~ 80 ° C
It is desirable to add a required amount of enzyme to a tower or the like and treat it.

The pulp used for the layer in contact with the innermost layer and the inner layer is not limited to the type of raw material, the pulping method, the bleaching method, and the presence or absence of beating treatment, as long as the pulp can be made by wet papermaking. . Modified pulp obtained by subjecting a chemical pulp to mercerization, liquid ammonia treatment, crosslinking treatment, or the like can also be used.

Thus, if necessary, various anionic, cationic or amphoteric retention improvers, drainage improvers, paper strength enhancers, and internal additives may be added to the pulp treated with enzymes after beating, if necessary. Papermaking internal additives such as sizing agents,
In addition, dyes, fluorescent brighteners, pH adjusters, defoamers, pitch control agents, slime control agents, etc. are added to prepare the stock for the outermost layer, and it is also necessary for pulp constituting other layers According to the above, various chemicals are added to prepare the stock. However, pulp constituting the other layers is appropriately selected from talc, heavy calcium carbonate, light calcium carbonate and the like and added to secure the opacity required by the paper. The pH during papermaking can be in the range of about 4.5 for acidic papermaking to 6 to 8 for neutral papermaking.

As for the method for producing the multilayer paper of the present invention, conventional papermaking techniques can be applied as appropriate, and a single head box for multilayer papermaking, for example, Strata by Beloit Co.
-flow, Tampera's Contro-flow, KMW's HTB-3L,
It may be manufactured using a multi-layering technique by a paper machine using Voith-Sluzer's Step Diffusor Headbox or the like.

The ratio of the outermost layer to the whole paper is preferably from 20 to 70% by weight in absolute dry weight ratio. If it is less than 20% by weight, the effect of the inner layer is strong and the smoothness is not sufficient, while if it exceeds 70% by weight, the effect of reducing the paper thickness and improving the rigidity is small. As described above, the ratio of the outermost layer to the whole paper is preferably from 20 to 70% by weight in absolute dry weight ratio, but the basis weight of the outermost layer needs to be at least 10 g / m ² or more. 1
If it is less than 0 g / m ² , it is difficult to completely cover the layer in contact with the outermost layer, and the effect of improving smoothness is reduced.

The obtained multilayer paper is coated on the surface of the paper with various size presses or coaters using various surfaces such as starch, polyvinyl alcohol, latex, alkyl ketene dimer, maleic anhydride, and styrene-acrylic acid. A sizing agent, a pigment, a dye, or the like may be applied.

The basis weight of the paper of the present invention is appropriately determined according to the application and purpose, but is selected from the range of 30 to 300 g / m ² . The thus obtained paper having excellent smoothness and rigidity of the present invention may be used as a high quality paper as it is, as a printing paper or an electrophotographic paper, and further coated on its surface with a paint containing a pigment or a binder as a main component. It can also be used as a base paper for paper, and even when finished in each product, the paper has excellent rigidity, so that the effect on weight reduction can be sufficiently maintained and contribute to the quality of the final product.

[0025]

EXAMPLES The present invention will be specifically described below with reference to examples, but of course, the present invention is not limited to these examples. In Examples and Comparative Examples, “%” means “% by weight” unless otherwise specified.

Example 1 (1) Preparation of paper stock constituting the outermost layer Factory-made hardwood bleached kraft pulp (hereinafter abbreviated as LBKP;
Whiteness 85.3%) was beaten at a pulp concentration of 4% to a CSF of 350 mL using a double disc refiner. An enzyme (trade name: Pergarase A4)
0, manufactured by Ciba-Geigy Co., Ltd.) was added to the absolutely dried pulp at 0.05%, and the mixture was treated under the conditions of pH 5.0, 50 ° C., and pulp concentration of 5% for 2 hours. At this time, the CSF of the pulp after the enzyme treatment was 450 mL (difference in CSF value before and after the enzyme treatment: 1
00 mL). Next, a rosin sizing agent for papermaking (trade name: Size Pine E, manufactured by Arakawa Chemical Industry Co., Ltd.) was added to the pulp slurry after the enzyme treatment with stirring while adding 0.5 to the absolute dry pulp weight.
%, The same sulfuric acid band as 3.0%, an anionic polyacrylamide-based paper strength agent (trade name: Polystron 19)
4-7, Arakawa Chemical Industry Co., Ltd.) was added at 0.05% to obtain a stock having a density of 0.6%.

(2) Preparation of paper stock constituting the intermediate layer Factory-made hardwood bleached kraft pulp (hereinafter abbreviated as LBKP;
Whiteness 85.3%) was beaten at a pulp concentration of 4% to a CSF of 450 mL using a double disc refiner. A rosin sizing agent for papermaking (trade name: Size Pine E, manufactured by Arakawa Chemical Industry Co., Ltd.) was added to the beaten pulp with stirring at a rate of 0.5% based on the absolutely dry pulp weight, and a sulfuric acid band was also added thereto.
0% and 0.05% of an anionic polyacrylamide-based paper strength enhancer (trade name: Polystron 194-7, manufactured by Arakawa Chemical Industry Co., Ltd.) were added to obtain a paper stock having a concentration of 0.6%.

(3) Preparation of Paper Sheet A JPRI multi-head box (Patent No. 15064) is prepared by using a stock constituting the outermost layer and a stock constituting the intermediate layer.
No. 70, Japan Pulp and Paper Research Institute), the outermost layer had a basis weight of 15 g / m ² , the middle layer had a basis weight of 30 g / m ² , and a total basis weight of 60 g. / M ² of a three-layer paper sheet. Then, a solution of oxidized starch (trade name: Ace A, manufactured by Oji Cornstarch) having a concentration of 4% was dried at a solid content of 2 g / m2.
² was applied by a two-roll size press for experiment and dried by a drum dryer for experiment.
The test was carried out at 0 kg / cm using an experimental calendar composed of two metal rolls to obtain a paper sheet having a basis weight of 62 g / m ² .

Example 2 As the pulp constituting the outermost layer, an enzyme (trade name: Besselex, manufactured by Godo Shusei Co., Ltd.) was added to LBKP beaten to 370 mL of CSF, and 0.04% of the pulp was added to the absolutely dried pulp.
Example 1 was the same as Example 1 except that pulp (CSF after enzyme treatment: 450 mL, difference in CSF value before and after enzyme treatment: 80 mL) treated with H5.0 at 50 ° C. and a pulp concentration of 5% for 2 hours was used. Similarly, a paper sheet of 62 g / m ² of ground paper was obtained.

Example 3 As the pulp constituting the outermost layer, an enzyme (trade name: Pergarase A4) was added to LBKP beaten to 310 mL of CSF.
0, manufactured by Ciba Geigy Co., Ltd.) was added to the absolutely dried pulp at 0.08%, and treated for 2 hours under conditions of pH 5.0, 50 ° C., and pulp concentration of 5% (CSF: 450 m after enzyme treatment).
L, a difference between CSF values before and after the enzyme treatment: 140 mL), and softwood bleached kraft pulp (hereinafter, abbreviated as NBKP, whiteness: 84.5%) was beaten to CSF 450 mL with a single disk refiner as the pulp constituting the intermediate layer. Except that the basis weight of the outermost layer was 18 g / m ² and the basis weight of the intermediate layer was 24 g / m ² .
A paper sheet having a basis weight of 62 g / m ² was obtained in the same manner as in Example 1.

Example 4 As a pulp constituting an intermediate layer, BCTMP (aspen 9) was used.
0%, Poplar 10%, Whiteness: 81.2%, CSF: 4
(00 mL), and a paper sheet having a basis weight of 62 g / m ² was obtained in the same manner as in Example 1.

Comparative Example 1 Pulp slurry of LBKP beaten to 450 mL of CSF
And a rosin sizing agent for papermaking with stirring (trade name: sa
Ispine E, Arakawa Chemical Industries)
0.5%, the same sulfate band 3.0%, anion
Polyacrylamide-based paper strength agent (trade name: POLYS)
TRON 194-7, manufactured by Arakawa Chemical Industries)
In addition, a stock with a concentration of 0.6% was obtained. Using this stock
Weighing 60 g / m by a laboratory round sheet machine^Two
Example 1 except that a paper sheet consisting of
62 g / m2 of ground paper in the same manner as 1. ^TwoPaper sheet was obtained.

Comparative Example 2 A pulp constituting the outermost layer of Example 1 was used, and a paper sheet having a basis weight of 62 g / m ² was obtained in the same manner as in Comparative Example 1.

Comparative Example 3 A pulp obtained by mixing the pulp constituting the outermost layer and the pulp constituting the intermediate layer in Example 1 at a ratio of 1: 1 was used, and in the same manner as in Comparative Example 1, the basis paper was 62 g / m ^2. Paper sheet was obtained.

Comparative Example 4 As the pulp constituting the outermost layer, an enzyme (trade name: Pergarase A4) was added to LBKP beaten to 410 mL of CSF.
0, manufactured by Ciba-Geigy Co., Ltd.)
The pulp was added and treated for 2 hours under conditions of pH 5.0, 50 ° C. and pulp concentration of 5% (CSF after enzyme treatment: 450 m
L, the difference between the CSF values before and after the enzyme treatment: 40 mL), except that the basis weight was 62 g / m ^{2 in the same} manner as in Example 1.
Paper sheet was obtained.

The obtained paper sheet was tested by the following test method to evaluate the quality. Evaluation method (1) Density: According to JIS P8118. (2) Gurley stiffness: J. TAPPI No. According to 40. (3) Smoothness: J. TAPPI No. 5 (Oken type smoothness tester).

The results obtained are shown in Table 1.

[0038]

[Table 1]

As can be seen from the table, the paper sheet of the present invention has excellent stiffness and also excellent smoothness (Examples 1 to 4). On the other hand, in the case of producing a single-layer paper, the stiffness was not sufficiently improved only with pulp that had been subjected to the enzyme treatment after beating (Comparative Example 2). Even if pulp not subjected to the above is mixed, the stiffness hardly improves (Comparative Example 3). In the case of multilayer paper, even when the effect of the enzyme treatment of the pulp constituting the outermost layer is small (the difference in the CSF value due to the enzyme treatment is 40 mL), the effect of improving rigidity and smoothness is small (Comparative Example 4).

[0040]

Industrial Applicability The present invention is a multi-layer paper having three or more layers, the outermost layer of which is made of chemical pulp treated with an enzyme having cellulolytic activity after beating, which has excellent rigidity and contributes to weight reduction. Can be high quality paper, information recording paper base paper,
This has the effect of providing paper suitable for printing paper and the like.

Claims (1)

[Claims] 1. A multilayer paper having three or more layers, wherein the multilayer paper has an outermost layer composed of chemical pulp treated with an enzyme having cellulolytic activity after beating treatment.