JPH06128891A - Production of paper and paper board - Google Patents

Abstract

PURPOSE:To improve the rigidity of produced paper and paper board by beating a pulp containing waste paper to lower the freeness and subsequently increasing the freeness by a specific treatment. CONSTITUTION:A pulp containing waste paper is beaten to lower its Canadian standard freeness and the pulp is treated with an enzyme having a (xylanase)/(CM-cellulase) activity ratio of 0.05-10 to increase the Canadian standard freeness. A paper and a paper board having improved rigidity can be produced without increasing the areal density and thickness or adding chemicals, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing paper and paperboard, and more particularly to a method for producing paper and paperboard with improved rigidity.

[0002]

2. Description of the Related Art Since paper and paperboard are usually used after being subjected to processing such as printing and box making, they are required to have basic properties as paper and paperboard as well as printability and boxing suitability. Above all, rigidity (stiffness) is a characteristic required for printing and box making.
Is a cause of paper jams when printing or copying machines, strength against crushing of boxes when filled with contents when stacked in a box, and body of a box when packed with powder etc. It is one of the important characteristics that is related to the strength against blisters. Therefore, it is desirable that the rigidity of the paper or paperboard is as high as possible, as long as it does not adversely affect other properties. On the other hand, in recent years, from the viewpoint of protecting the global environment, saving of wood resources and recycling of paper have been encouraged, and used waste paper has been widely used as a pulp raw material.

However, from the viewpoint of the stiffness of paper and paperboard as pulp raw materials, it is known that the waste paper is less rigid than the virgin pulp, and the use of a large amount of waste paper is not suitable for the paper which needs the rigidity. There is a problem that it works negatively, in the production of paper and paperboard for these applications using waste paper, a method of increasing the basis weight, making the density as low as possible to make the thickness thick, and making the paper bulk, or Relatively strong N
Measures such as blending (coniferous) pulp, internal addition of various sizing agents, paper-strengthening agents, coating and, in some cases, refining used pulp are taken and proposed in the actual operation of the factory. It was However, all of these lead to cost increase, and there are drawbacks such that advancing the beating of used pulp generally increases the density of paper and makes it difficult to obtain bulk, and a method that is sufficiently satisfactory to solve the above problems. Was not found and a proper solution was required.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above problems by increasing the basis weight and thickness of paper and paperboard.
Another object of the present invention is to provide a method for producing paper and paperboard, which improves the rigidity of paper and paperboard without depending on the method of adding chemicals. Another object of the present invention is to provide a method for producing paperboard that improves the rigidity of multilayer paperboard that is often used in various paper boxes such as paper containers.

As a result of studying the above-mentioned problems, the present inventors beat pulp containing waste paper to lower the Canadian standard freeness (hereinafter abbreviated as CSF), and then determine the xylanase activity / CM-cellulase activity. The inventors have found that the rigidity of paper and paperboard can be improved by treating pulp with waste paper whose CSF has been increased by treating it with an enzyme having a ratio within a specific range, and completed the present invention. Further, pulp containing waste paper is treated with an enzyme having a ratio of xylanase activity / CM-cellulase activity in a specific range to raise CSF to a specific range, and then beaten to lower CSF to the specific range. It was also found that the rigidity of paper and paperboard can be improved by making pulp containing waste paper, and the present invention has been completed.

[0006]

That is, according to the present invention, after the pulp containing waste paper is beaten to lower the Canadian standard freeness, the ratio of xylanase activity / CM-cellulase activity is 0.
It is a method for producing paper, which is characterized in that pulp made by treating with an enzyme in the range of 05 to 10 to raise the standard drainage of Canada is made.

In the present invention, pulp containing waste paper is treated with an enzyme having a xylanase activity / CM-cellulase activity ratio of 0.05 to 10 to increase Canadian standard freeness by 50 to 70 ml and then beaten. Then, the pulp of which the Canadian standard freeness has been lowered by 50 to 70 ml is made into a paper.

Furthermore, the present invention is a method for producing a paperboard comprising at least a surface layer, a middle layer and a back layer, wherein pulp containing waste paper is beaten to lower the Canadian standard freeness, and then the xylanase activity / CM-cellulase activity is measured. A paperboard manufacturing method, characterized in that a pulp containing waste paper whose Canadian standard freeness has been increased by treating with an enzyme having a ratio in the range of 0.05 to 10 is used as a backing layer of the paperboard. .

Furthermore, in the present invention, in a method for producing a paperboard comprising at least a surface layer, a middle layer and a back layer, pulp containing waste paper is treated with an enzyme having a ratio of xylanase activity / CM-cellulase activity in the range of 0.05 to 10. In the method for producing a paperboard, which is characterized by using the backing layer of the paperboard to make a pulp containing waste paper that has been beaten to lower the Canadian standard freeness after increasing the Canadian standard freeness. is there.

It has been conventionally known that an enzyme is added to beat. For example, JP-A-60-126395 proposes to add a cellulolytic enzyme (cellulase) to pulp for beating, and JP-A-1-92490 discloses to add cellulase having PH of 7 or more to pulp. It is proposed to be beaten. However, both proposals are aimed at reducing the beating power, and after adding cellulase and leaving it for about 30 minutes, beating is performed.

Further, Japanese Unexamined Patent Publication No. 2-118191 discloses a method for producing a mechanical pulp in which an enzyme having a pectin-degrading activity is added to the mechanical pulp, which is then subjected to beating to further reduce the CSF. There is.

Pectin is composed of a linear polymer in which D-galacturonic acid is bound to α-1,4, and its carboxyl group partially forms a methyl ester, and some forms a salt with a metal ion. Is a polysaccharide with a completely different structure. Pectinase is an enzyme that hydrolyzes α-1,4 bond of pectin into endo type, is classified into EC3.2.1.15, and is an enzyme completely different from xylanase used in the present invention. Further, the object of the present invention is to improve the whiteness of paper, whereas the present invention is to improve the rigidity of paper and paperboard, which is completely different.

Further, JP-A-3-228685 discloses a defibrating composition having a defibrating activity for newspapers and copy papers, which has a low CM-cellulase activity and a xylanase activity.
The purpose is to carry out pulp defibration and beating treatment by using an enzyme having weak CM-cellulase activity and xylanase activity and strong defibration activity, and minimizing damage to carbohydrates such as cellulose and hemicellulose as much as possible. And CM
The technical idea is completely different from that of the present invention in which the cellulase activity and the xylanase activity are actively used.

The method for producing paper and paperboard of the present invention will be described below. The method for producing paper according to the present invention comprises treating pulp containing waste paper with a enzyme having a ratio of xylanase activity / CM-cellulase activity in the range of 0.05 to 10 after beating to lower CSF and before papermaking. Is a method for making pulp containing waste paper with increased CSF.

Further, in the paperboard manufacturing method of the present invention, pulp containing waste paper is treated by the same processing means as in the above-mentioned paper manufacturing method, and is used as a backing paper stock for a multilayer paperboard. Surface layer of the other layer that is sequentially laminated by the method,
This is a manufacturing method in which the non-papermaking surfaces of the front and bottom layers and the middle layer are used as back layers.

After beating the pulp containing the waste paper of the present invention,
CS to be lowered during beating in the method of performing enzyme treatment
The range of CSF increased by F and enzyme treatment is 50 to 150 m
l is preferred. If less than 50 ml, there is little improvement in rigidity, 150 ml
If it is increased over the range, the strength is lowered, which is not preferable.

In the method of beating after the enzyme treatment, the range of CSF increased by the enzyme treatment and lowered CSF during the beating is preferably 50 to 70 ml, which is different from the above beating-enzyme treatment. Since this is easily beaten by the enzyme treatment, the fibers are easily cut at the time of beating and the paper strength is reduced. Therefore, it is preferable to keep the increase in CSF by the enzyme treatment to a small extent. For this reason, as the enzyme treatment condition, it is necessary to carry out a relaxation treatment such that the amount of enzyme to be added will be on the smaller side or the enzyme treatment time will be as short as possible. However, when the waste paper pulp slurry of the present invention obtained by the method of beating after enzyme treatment is used for the backing layer of paperboard, CSF 50-70 ml and 100 ml
There is no difference in stiffness. This is considered to be because the ratio of the thickness of the backing layer to the total thickness of the paperboard is as small as 1/8 to 1/10, and therefore the influence of the Young's modulus is larger than the thickness.

An enzyme having at least a CM-cellulase activity and a xylanase activity is used as the enzyme of the pulp containing the waste paper of the present invention. The cellulase referred to in the present invention is an enzyme that hydrolyzes the β-1,4-glycoside bond of cellulose to an endo type, and for example, endo-β- (1,4) -glucanase classified into EC number 3.2.1.4. Refers to. Hydrolyze cellulose to exo type, β-D-glucosidase classified into EC number 3.2.1.21, exo-1,4-β-D-glucosidase classified into EC3.2.1.74 and EC3.2.
Exocellobiohydrolases classified as 1.91 are CS
It does not increase F and does not exert the effect of improving rigidity.

Xylan is a polysaccharide having side chains such as L-arabinose and D-glucuronic acid in the main chain of β-1,4-bonded xylopyranose. The xylanase referred to in the present invention is an enzyme that hydrolyzes β-1,4 xyloside bond of xylan to endo type, and is classified into EC 3.2.1.8. It is not always clear at this stage why an enzyme having both CM-cellulase and xylanase activity raises CSF. With the CM-cellulase activity alone, the xylan remaining in the mechanical pulp or the xylan re-deposited during cooking inhibits the cellulase's access to cellulose and the reaction. However, the xylanase activity decomposes this xylan, and the CM-cellulase activity It is thought that it is to help the work of. Also, xylanase activity and C
The combined use of M-cellulase activity causes solubilization of fine fibers and fibrils contained in waste paper pulp, resulting in C
It is considered that the SF becomes higher. On the other hand, when the xylanase activity is too strong, xylan is decomposed more than necessary, so that beating of the fiber, that is, fibrillation becomes difficult to occur, and rigidity and other paper strength are unfavorably affected.
It has been found that the ratio of xylanase activity / CM-cellulase activity is preferably in a certain range.

Xylanase activity / CM-used in the present invention
As an enzyme having a cellulase activity ratio in the range of 0.05 to 10, CM-cellularase xylanase xylanase activity active CM-cellulase activity Liftase A40 8.1 0.5 0.06 Besserex (purified joint liquor) 6.7 3.9 0.58 Hemicellulase (same as above) 6.1 9.0 1.48 In addition to this, pulpzyme (manufactured by Novo, Denmark) and the like can be mentioned.

According to the results of the study by the present inventor, in the present invention, both the CM-cellulase activity and the xylanase activity are present, and at the same time, the xylanase activity / CM-cellulase activity ratio is in the range of 0.05-10. It has been confirmed that it is in a preferable range for achieving the purpose of improving the rigidity of paper and paperboard.

By the way, the following enzymes out of the scope of the present invention were not found to have the effect of improving the rigidity of paper and paperboard. CM-Cellular xylanase xylanase active active Active CM-cellular xy active PSDL 401 13.4 0.1 0.01 0.01 Albazyme 10 2.4 38.6 16.08 SP 473 0.02 33.3 1665

These enzymes may be used alone or in combination and may be used in an amount of 0.03 to 3% by weight (vs. dry pulp), preferably 0.1 to 3.
1% by weight is added to the pulp slurry. The enzymes having a ratio of xylanase activity / CM-cellulase activity within the above range may be enzymes produced by the same organism, or may be used by mixing enzymes produced by different organisms. The concentration of the pulp slurry in the enzyme treatment is adjusted to 1 to 10% by weight, preferably 2 to 5% by weight, and the PH is adjusted to 4 to 7, preferably 5 to 6.

The temperature of the enzyme treatment is 20 to 60 ° C., preferably 40 to 50 ° C., and the treatment time is at least 1 hour because the contact time between the enzyme and the pulp is sufficient, and it is about 2 days at the longest. to continue.

The pulp which is the target of enzyme treatment and beating treatment in the method of the present invention contains 50 to 100% of waste paper, and in the case of paperboard, only the pulp of the back layer contains 50 to 100% of waste paper, There is no particular limitation on the content of waste paper in the other surface layers, the lower surface layer and the middle layer. The pulp containing waste paper may include waste paper pulp that has been deinked or waste paper pulp that has not been deinked.

[0026]

In the production method of the present invention, the rigidity of the paper and the paperboard is improved because the pulp containing waste paper is treated with a specific enzyme so that the pulp fiber of the waste paper is gently disentangled. This is because the Young's modulus of paper and paperboard is improved in combination with the beating process performed before or after that.

In the case of paperboard, this is due to the fact that the density of the backing layer and Young's modulus of the back, which have a large proportion of waste paper pulp in each of the front, middle and back layers, and which account for a small proportion of the total thickness of the paperboard. Therefore, if the method of the present invention is applied to the middle layer having a large proportion of the total thickness, the total thickness of the paperboard may be thinned and the rigidity may be lowered, which is not preferable.

[0028]

EXAMPLES The present invention will be specifically described with reference to the following examples. Example 1 CSF25 disaggregated from 100% magazine waste paper with a pulp concentration of 3.5%
4 ml of waste paper pulp slurry was beaten to 146 ml with a PFI mill. Then, in a waste paper pulp slurry whose pH was adjusted to 5.5, the ratio of xylanase activity / CM-cellulase activity was 0.58.
0.2% (vs. dry pulp) of VESSELEX (purified joint liquor) was added and reacted at a temperature of 40 ° C for 20 hours.
l of waste paper pulp slurry was obtained. Table 1 shows the quality test results obtained by converting the obtained waste paper pulp into sheets using a known hand sheet machine.

Examples 2 to 6 In Example 1, except that the CSF of the waste paper pulp beaten with the PFI mill, the enzyme used for the enzyme treatment, the treatment time and the CSF of the waste paper pulp obtained were as shown in Table 1. Table 1 shows the results of a quality test performed on a waste paper pulp sheet obtained in the same manner as in Example 1.

Comparative Examples 1 and 2 In the same manner as in Example 1, except that the CSF of the waste paper pulp beaten with the PFI mill and the enzymes used in the enzyme treatment are as shown in Table 1 in Example 1, the waste paper pulp is exactly the same. Table 1 shows the results of the quality test performed on the sheet No. Comparative Example 3 In Example 1, the quality test results are shown in Table 1 where the waste paper pulp slurry of 254 ml of CSF that was not beaten by the PFI mill and not subjected to the enzyme treatment was formed into a sheet.

[0031]

[Table 1] Table 1 Actual Example Comparative Example 1 2 3 4 5 6 1 2 3 PFI After milling CSF (ml) 146 194 146 194 194 194 194 194 Lower CSF (ml) 108 60 108 60 108 60 60 60 Enzymes used * VVHH V + H V + HPA Ratio of both activities ** 0.58 0.58 1.48 1.48 1.03 1.03 0.01 16.08 Addition rate (%) 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Temperature (° C) 40 40 40 40 40 40 40 40 hours (Hr) 20 5 20 5 20 5 20 20 CSF after treatment (ml) 257 251 246 247 255 248 208 202 Ascending CSF (ml) 111 57 100 53 109 54 14 8 Basis weight (g / m ² ) 60.6 60.7 60.4 60.2 60.5 60.8 60.9 Density (g / cm ³ ) 0.528 0.509 0.525 0.503 0.521 0.510 0.495 Rigidity (cm / 100) 129 128 129 130 130 129 118 Young's modulus (GPa) 1.97 1.73 1.95 1.74 1.97 1.75 1.57 Cleavage Length (Km) 3.02 2.93 3.03 2.91 3.01 2.94 2.70 * Enzyme abbreviation used V: Vesselex Godo Shusei Co. H: Hemicellulase As above P: PSDL401 Showa Denko A: Albazyme Nagase Biochemical ** * Both Ratio of activity Xylanase activity / CM-cellulase activity

Quality Test Method Basis Weight JIS P8124 Density JIS P8118 Rigidity JIS P8143 Young's Modulus TENSILON UCT-IT (ORIENTEC CORPORATIO
Measured according to JIS P8113

From the results shown in Table 1, (a) the enzymes of the present invention having a xylanase activity / CM-cellulase activity ratio in the range of 0.05 to 10 are used alone or in combination,
The paper stiffness (128-130 cm / 100) of the paper obtained by beating the waste paper pulp with the enzyme treatment after beating is the paper stiffness of the paper obtained from the waste paper pulp of the same level without the enzyme treatment (1
Compared to 18 cm / 100), it is improved by 8.5 to 10.2%. (B) When an enzyme having a ratio outside the ratio of xylanase activity / CM-cellulase activity of the present invention was used, it was not possible to raise the CSF before beating by the enzyme treatment after beating, and a sample for paper quality test Was not obtained.

Example 7 Waste paper of 100% magazine was disintegrated at a pulp concentration of 3.5% and PH was adjusted to 5.5.
0.2% (versus dry pulp) of Vesselex having a xylanase activity / CM-cellulase activity ratio of 0.58 was added to 254 ml of CSF prepared as above.
The CSF after reacting for a time was 308 ml. Then P
It was beaten with an FI mill to obtain 252 ml of CSF waste paper pulp slurry. The obtained waste paper pulp is formed into a sheet by a known hand sheet sheet machine, and the quality test is performed.
Shown in.

Example 8 and Comparative Example 4 In Example 7, the reaction time of the enzyme treatment and the CS after the treatment were used.
Table 2 shows the results of a quality test conducted on a waste paper pulp sheet obtained in the same manner as in Example 7 except that the CSF after beating of the F and PFI mills was changed as shown in the table.

Comparative Examples 5 and 6 The results of quality tests of waste paper pulp sheets obtained in the same manner as in Example 7 except that the enzymes used in the enzyme treatment were as shown in Table 2 were carried out. Is shown in Table 2.

[0037]

[Table 2] Table 2 Examples Comparison Example 7 8 4 5 6 3 Enzyme used VVVPA Ratio of both activities 0.58 0.58 0.58 0.01 16.08 Addition rate (%) 0.2 0.2 0.2 0.2 0.2 Temperature (℃) 40 40 40 40 40 Time (Hr) 5 10 20 20 20 Post-treatment CSF (ml) 308 323 359 262 259 Up CSF (ml) 54 69 105 8 5 PFI After milling CSF (ml) 252 254 256 Down CSF (ml) 56 69 103 Basis weight (g / m ² ) 60.9 61.0 61.3 60.9 Density (g / cm ³ ) 0.506 0.511 0.520 0.495 Rigidity (cm / 100) 128 127 124 118 Young's modulus (GPa) 1.68 1.74 1.80 1.57 Rupture length ( Km) 2.85 2.88 2.68 2.70

From the results shown in Table 2, (a) when an enzyme having a ratio of xylanase activity / CM-cellulase activity of the present invention within the range is used, even if beating is performed after first performing the enzyme treatment. , The stiffness of the resulting paper is
It is improved as compared with the paper stiffness (118 cm / 100) of untreated (Comparative Example 3) and the same level of CSF paper. However, the extent of the improvement depends on the width of the rise and fall of CSF.
50-70ml (paper stiffness 127-128cm / 100) improves 7.6-8.5%, but 100ml (paper stiffness 124cm / 100) 5.1%
To improve. (B) When an enzyme having a xylanase activity / CM-cellulase activity ratio outside the range of the present invention is used, C by the enzyme treatment is used.
The increase in SF was slight, there was no room for beating, so-called beating margin, and the initially intended enzyme-beating treatment could not be performed.

From the results shown in Tables 1 and 2 above, when the beating-enzyme treatment and the enzyme-beating treatment are compared, the paper stiffness of the beating-enzyme hardly changes when the CSF width is 50 ml (beating-enzyme average 129.0, Enzyme ~ Beating 128), 100 ml of CSF
When changed, the enzyme-reducing the paper stiffness of the beating (124 cm / 10
0), so beating-enzyme treatment is preferable.

Examples 9 to 14 and Comparative Example 7 NBKP 32% and LBKP68 as the surface layer pulp composition of paperboard.
% CSF 348 ml, lower and upper layer pulp 100% medium white recycled paper CSF 229 ml, middle layer pulp 100% magazine CSF 276 m
Each of the l-type paper and the waste paper pulp obtained in Examples 1 to 6 was used as the backing layer pulp, and papermaking was performed with a hand-making sheet machine to obtain a multilayer paperboard. Further, for comparison, Examples 9 to 1 except that the untreated waste paper pulp of Comparative Example 1 was used.
A multilayer paperboard was obtained in exactly the same manner as in 4. Table 3 shows the test results of the obtained multilayer paperboard.

[0041]

[Table 3] Table 3 Actual Example Comparative Example 9 10 11 12 12 13 14 7 Pulp used in back layer Actual 1 Actual 2 Actual 3 Actual 4 Actual 5 Actual 6 Ratio 3 Basis weight (g / m ² ) 375 375 375 374 375 376 374 Density (g / cm ³ ) 0.631 0.627 0.633 0.625 0.631 0.624 0.626 Rigidity * (gf cm) 207 200 206 201 206 203 190 Basis weight after correction ** (gfcm) 207 200 206 202 206 202 191 Tear length ( Km) 3.04 2.97 3.04 2.96 3.03 2.95 2.91 Quality test method * Stiffness according to JIS P8125 ** Stiffness after correction of grammage Rigidity measured based on 375 g / m ^{2 of} grammage

According to the results shown in Table 3, unprocessed waste paper pulp is processed as a back layer by combining waste paper pulp that has been subjected to the enzyme treatment after beating with the enzyme of the present invention with the back layer of paperboard. Rigidity of paperboard is about 4.7-8.4% compared to conventional
improves. Looking at the fluctuation range of CSF, it is 100 ml than about 50 ml
The effect of improving the rigidity is greater when the CSF is beaten to some extent and then returned to the original CSF by the enzyme.

In Examples 15 to 17 and Examples 9 to 14, Example 7 was used as the back layer pulp.
8. A multilayer paperboard was obtained in the same manner except that the waste paper pulp obtained in Comparative Example 4 was used. Further, for comparison, quality test data of a multilayer paperboard using the untreated pulp of Comparative Example 3 as a backing layer is re-written. Table 4 shows the test results of the obtained multilayer paperboard.

[0044]

[Table 4] Table 4 Actual Example Comparative Example 15 16 17 7 Pulp used for backing layer Actual 7 Actual 8 Ratio 4 Ratio 3 Basis weight (g / m ² ) 374 375 376 374 Density (g / cm ³ ) 0.629 0.630 0.631 0.626 Stiffness * (gf cm) 196 199 201 190 After adjustment of basis weight ** (gfcm) 197 199 200 191 Rupture length (Km) 2.94 2.96 2.92 2.91

From the results shown in Table 4, the conventional untreated waste paper pulp is used as the back layer by combining the waste paper pulp enzyme-beaten with the enzyme of the present invention with the back layer of the paperboard. Compared with, it is improved by 3.1 to 4.7%. In addition, in Table 2, 100 ml of CSF was raised and lowered, and the paper stiffness when the used pulp was lowered was reduced, but when it was used for the back layer of the paper board of Table 4, the fluctuation range of CSF was 50-100 ml. There is almost no difference in paper stiffness between them. This is probably because the ratio of the thickness of the backing layer to the total thickness of the paperboard is as small as 1/8 to 1/10, so the Young's modulus is more important than the thickness.

From Tables 3 and 4 above, when the effects of beating-enzyme treatment and enzyme-boarding on the stiffness of the paperboard are compared, beating-enzyme average 205.3 gfcm, when the CSF fluctuation range is 100 ml.
Enzyme ~ Beating 200gfcm difference can be seen, but 50ml beats ~
Enzyme average 200.0gfcm, enzyme ~ beating 197gfcm, almost no difference. From this, the xylanase activity of the present invention /
When used paper pulp treated with an enzyme having a CM-cellulase activity ratio within the range is combined with the back layer of the paperboard, beating-enzymatic treatment is more effective than enzyme-beating treatment in improving stiffness of the paperboard. In particular, it is preferable that the fluctuation range of CSF is about 100 ml.

[0047]

The method for producing paper and paperboard of the present invention uses the recycled pulp which is hard to produce stiffness as the raw material pulp.
Since the rigidity of paper and paperboard can be improved without increasing the basis weight and thickness and without adding chemicals, it can be easily applied to the operation of a paper mill. Therefore, it can be used in applications requiring rigidity such as paperboard for paper containers, which greatly contributes to the recycling of waste paper and the large-scale use.

Claims (4)

[Claims] 1. A pulp containing waste paper is beaten to lower the Canadian standard freeness, and then treated with an enzyme having a ratio of xylanase activity / CM-cellulase activity in the range of 0.05 to 10 to obtain Canadian standard drainage. A method for producing paper, characterized in that pulp having an increased degree is produced. 2. A pulp containing waste paper is treated with xylanase activity /
After treatment with an enzyme having a CM-cellulase activity ratio in the range of 0.05 to 10 to increase the Canadian standard freeness by 50 to 70 ml,
A method for producing paper, which comprises making pulp by beating to reduce the Canadian standard freeness by 50 to 70 ml. 3. A method for producing a paperboard comprising at least a surface layer, a middle layer and a back layer, wherein pulp containing waste paper is beaten to lower the Canadian standard freeness and then xylanase activity / C
A paperboard characterized in that it is used as a backing layer of the paperboard by making pulp containing waste paper treated with an enzyme having an M-cellulase activity ratio in the range of 0.05 to 10 to increase Canadian standard freeness. Manufacturing method. 4. A method for producing a paperboard comprising at least a front layer, a middle layer and a back layer, wherein pulp containing waste paper is treated with an enzyme having a xylanase activity / CM-cellulase activity ratio of 0.05 to 10 to obtain a Canadian standard filter. After raising the water level,
A method for producing paperboard, which comprises making pulp containing waste paper that has been beaten to reduce the Canadian standard freeness and used as a back layer of the paperboard.