JPH0813367A - Production of pulp - Google Patents

Abstract

PURPOSE:To obtain pulp useful for producing paper and board paper from nonwoody resources without discharging a large amount of waste liquor by treating a fiber source derived from a nonwoody plant such as rice plant straw, wheat straw or bagasse with an enzyme having xylan hydrolyzing activity. CONSTITUTION:A source of a nonwoody plant is treated with an enzyme having xylan hydrolyzing activity at normal temperature under normal pressure to remove lignin without causing waste water having 'a-an undesirable influence on the natural environment. The xylan hydrolyzing enzyme may be derived from a microorganism, an animal or a plant and the added amount of the enzyme is 0.01-10wt.% based on the dry weight of the fiber source.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently producing pulp or paper, which is characterized by enzymatically treating non-wood plant resources such as rice straw, wheat straw, bagasse (sugar cane squeezed lees).

[0002]

2. Description of the Related Art In Japan, 99% or more of wood has been relied on as a pulp raw material, but in recent years, a worldwide shortage of wood resources has begun to be recognized, and awareness of global environment protection has increased. Conservation is of interest. Therefore, non-wood type plant resources such as rice straw, wheat straw, and bagasse, which have been generated in large quantities each year and have been discarded as agricultural waste, have been attracting attention.

Conventional pulping from non-wood resources such as rice straw, wheat straw, and bagasse is known as a soda method and a kraft method. In these methods, rice straw and wheat straw as raw materials are heated to 140 to 170 degrees under alkaline conditions and treated at high temperature and high pressure, that is, they are cooked to remove lignin, but the yield is low in the soda method. That is, it is difficult to treat the cooking waste liquor, and the kraft method has the additional disadvantage of generating malodorous substances, which is one of the factors that prevent the spread of pulping from non-wood resources. Especially for cooking waste liquor, the content of silica (SiO ₂ ) in rice straw and wheat straw as raw materials is high, and soluble Na ₂ SiO ₃ is dissolved in the black liquor during the cooking process to recover each process. Is known to cause trouble. For example, in an evaporator, the scale adheres remarkably and has a high viscosity, so that it is difficult to concentrate at a high concentration. Further, in the recovery boiler, silica (SiO ₂ ) raises the melting point of ash, causing the boiler to become dirty and clogged. In the causticizing process, CaSiO ₃ is produced, dissolved in white liquor and circulated to accumulate silica in the system. Due to such problems in collecting chemicals, it is practically impossible to collect chemicals, especially when rice straw having a high silica content is used as a raw material, and it is discarded as a waste liquid, which is a great environmental problem. Although it is sufficient to treat the waste liquid, it is one of the major reasons why it is economically unsuccessful because it requires a great deal of expense.

On the other hand, regarding the production of pulp from enzymes from non-wood resources, a method for producing pulp for pulp from bast fibers (JP-A-53-28701) and a method for pulping non-wood fibers (JP-B-57). No. 39636), a method for producing pulp by an enzyme (Japanese Patent Laid-Open No. 59-223389) and the like are known, but all of them target hemp fibers represented by flax and jute, bast fibers such as Mitsumata and Kozo. It is a thing.
Enzyme pulp production methods suitable for hard fibers composed of grass vascular bundles such as rice, wheat and bagasse are not known.

[0005]

DISCLOSURE OF THE INVENTION The present invention relates to a novel pollution-free pulp alternative to conventional chemical methods, which is difficult to treat wastewater and to control malodor when utilizing non-wood resources such as rice straw, straw and bagasse. It aims at providing the manufacturing method of.

Further, it is an object of the present invention to provide a new and effective pulp production method which replaces the conventional enzyme pulp production method which is not suitable for pulping non-wood resources. Another object of the present invention is to provide a novel method for manufacturing paper / paperboard.

[0007]

[Means for Solving the Problems] Pulp is obtained by taking out fibers, which are raw materials for papermaking, from a plant, and cellulose is the main constituent of the fibers for papermaking. Rice straw, which is the raw material,
Although the chemical composition of straw and bagasse is complex, it is composed of three major components: cellulose, hemicellulose, and lignin. Others include oils and fats, small amounts of protein, and ash such as silica. It is not always entirely clear how these components are bound to each other. However, although it is a fragmentary finding, according to a report on straw lignin, three types of lignin, that is, alkali-extracted lignin, finely-pulverized and extracted lignin, and enzyme-extracted lignin were isolated from wheat straw, and as a result, their characteristics were examined. The lignin in it has a strong bond with the hemicellulose, arabinoglucuronoxylan, but it is presumed that it is a cross-linking bond via ferulic acid.

In addition, the lignin sugar complex of bagasse (Lig
nin-carbohydrate complex: L
The structure of (CC) was elucidated, and it contained ferulic acid and p-coumaric acid, and the sugar component was arabinoglucuronoxylan consisting of arabinose and xylose at a ratio of 1: 8. It is presumed that its binding mode with lignin may be a benzyl ester or benzyl ether bond.

In the conventional method, high temperature and high pressure treatment under alkaline conditions was carried out for pulping for the purpose of removing lignin, but the present inventors easily decomposed xylan which is hemicellulose bound to lignin. As a result of intensive studies based on the consideration that lignin can be removed, the present invention has been completed. That is, the method for producing a pulp according to the present invention is characterized by subjecting raw materials rice straw, wheat straw, bagasse, etc. to enzyme treatment under normal temperature and normal pressure to generate waste water that adversely affects the natural environment. It is characterized by not having.

[0010]

DISCLOSURE OF THE INVENTION That is, the present invention provides the following pulp production method and paper / paperboard production method. 1) A method for producing pulp, which comprises treating a fiber source derived from a non-wood plant with an enzyme having a xylan-decomposing activity. 2) The method for producing pulp as described in 1) above, wherein the fiber source is agricultural waste. 3) The method for producing pulp according to 1), wherein the non-woody plant is a monocot. 4) Fiber sources derived from non-wood type plants are rice straw, wheat straw, bagasse,
The method for producing a pulp according to 1) above, which is a corn cob, a cottonseed meal or an oat seed coat. 5) A method for producing pulp, which comprises subjecting the obtained pulp to reduction bleaching and / or oxidative bleaching after the treatment described in 1) to 4) above. 6) A method for producing paper / paperboard, which comprises filtering the obtained pulp after the treatment described in 1) to 5) above. 7) A method for producing paper / paperboard, characterized in that after the treatments described in 1) to 5) above, the obtained pulp is blended with chemical pulp and strained.

The target of the enzyme treatment in the present invention is a fiber source derived from a non-wood plant, preferably a monocot plant derived fiber source or agricultural waste, more preferably rice straw, wheat straw, Examples include bagasse, corn cobs, cottonseed meal and oat seed coat. It is better to wash and remove the soil and mud adhering to these raw materials before applying the enzyme.
In addition, pulping can be performed more easily by pretreating the raw material, that is, after making the enzyme more easily act on the raw material, and then treating with the enzyme. The pretreatment method is a method in which the raw material is lightly defibrated by a mechanical treatment using a hydropulper or a press, a method in which it is chemically treated by immersing it in an alkali such as sodium hydroxide to swell the structure, or a mechanical treatment and a chemical treatment. It is possible to use a treatment method in which a specific treatment is combined.

As xylan-degrading enzymes, microorganisms, animals,
It may be of any origin such as a plant, and may be a crude product as well as a purified product. These enzymes can be used alone or in combination or sequentially and are added in an amount of 0.01 to 10% by weight based on the dry weight of the fiber source derived from a non-wood system.

The presence or absence of xylan-degrading activity of the enzyme can be examined by the following method as a simple method. That is, commercially available oat-derived xylan (SIGMA) was suspended in an aqueous solution adjusted to an arbitrary pH so as to have a concentration of 1% by weight, and agar was added so as to have a concentration of 2% by weight, and then 90 to 100 ° C. Heat up to make agar plate. The enzyme solution is appropriately diluted or concentrated, spotted on an agar plate, and then kept at an arbitrary temperature. After 24 hours, the agar plate was observed, and if a clear zone was observed in the spotted peripheral area, it was determined to have xylan-decomposing activity.

In the enzyme treatment, the raw material concentration is 0.1
% By weight to 20% by weight, preferably 1 to 10% by weight. The closer the pH and temperature conditions are to the optimum conditions for the decomposition activity, the more effective it is. Usually pH is 3-1
1. The temperature can be selected from the range of 10 ° C to 90 ° C. The treatment time is influenced by the treatment pH, the treatment temperature and the amount of enzyme. It is also affected by the type of raw material such as rice straw, wheat straw and bagasse, and the degree of pretreatment. If it is left standing or treated with gentle stirring, it takes about 1 hour if it is short and about 10 days if it is long. The enzyme treatment conditions may be determined in consideration of the constraints on actual production. It is desirable to set the optimum conditions after conducting a preliminary test.

Furthermore, pulping can be more easily carried out by preliminarily or simultaneously acting an oil-degrading enzyme or a protein-degrading enzyme in order to decompose oils and fats and proteins contained in the raw material. In the case of a cellulolytic enzyme, it is not preferable because the fiber itself is decomposed to lower the yield and the pulp strength, but for example, when pulp strength is not so required, it is easier to act the cellulose degrading enzyme in advance or simultaneously. Can be pulped. In these cases as well, the closer to the optimum condition of the decomposition activity the more effective it is from the characteristics of the enzyme used, but it is not necessary to be particular about it and it may be within the range where the enzyme acts.

The enzyme-treated raw material is often in a state in which fibers are still bound or non-fiber components are attached, and the raw material cannot be directly formed into paper.
Therefore, after disintegrating or beating, the fibers are often separated and acquired. Disaggregation and beating are pulper, beater, refiner,
It can be processed using a PFI mill or the like. The disaggregation or beating is preferably carried out under alkaline conditions for the purpose of further swelling the tissue of the raw material and for the purpose of extracting lignin, but it is not always limited to this. In order to carry out under alkaline conditions here, it is preferable to take a method of immersing the raw material in the alkaline solution before the enzyme treatment, but the alkaline solution after use can also be used for immersing the next raw material. Since it can be recycled again, it does not generate a large amount of waste liquid unlike the conventional soda method.

The separation treatment can be performed with a wet rotary sieve, a flat screen, a pressure screen or the like. It is effective to separate the fiber and non-fiber components by using two or more sieves of the same type or different types.

Thereafter, if necessary, reduction bleaching and / or oxidative bleaching according to a standard method can be carried out to obtain paper / paperboard pulp. For example, for reduction bleaching, the pulp concentration is 3 to 5%, the pH is 5 to 6, and the temperature is 50 to 65 ° C.
Sodium hydrosulfite vs. dry pulp 0.5
~ 1.0 wt% is added and treated for 0.5-1.0 hours.

For oxidative bleaching, chlorine water, sodium hypochlorite, chlorine dioxide, hydrogen peroxide, etc. can be used. For example, when sodium hypochlorite is used, the pulp concentration is 3 to 5%, the temperature is 25 to 50 ° C,
Treat with 2-9% of available chlorine for 2-6 hours. For oxidative bleaching, it is preferable to carry out multi-step treatment using two or more chemicals. When using a chlorine-containing chemical such as sodium hypochlorite, chlorine water or chlorine dioxide, it is preferable to carry out an alkali extraction operation.

Paper / paperboard can be produced from the obtained pulp, if necessary, by a paper preparation method according to a standard method. For example, good handmade paper can be obtained by the method for preparing handmade paper for JIS P8209 pulp test. Further, it is also possible to mechanically prepare paper using a paper machine such as a Fourdrinier paper machine or a cylinder paper machine.

[0021]

The present invention will be described in more detail with reference to the following examples, but the invention is not limited thereto.

Example 1 A microorganism producing an enzyme having a xylan-degrading activity was screened from nature. As a screening method, a suspension of soil collected from various places was appropriately diluted and applied to a plate agar medium having the composition shown below. Clear zones are found around colonies that appear on plate agar after culturing at 50 ° C for 24 hours (strain A, strain B, strain C)
Was selected. The composition of the plate agar medium for screening is 1% xylan (derived from oats), 0.1% asparagine,
Yeast extract 0.1%, KH ₂ PO ₄ 0.05%, MgS
O ₄ / 7H ₂ O 0.02%, NaCl 0.02%, Fe
After adjusting the pH to 7 with Cl ₃ 0.002% and agar 2%, it was sterilized by autoclaving at 121 ° C. for 20 minutes.

The obtained microorganism was shake-cultured for 3 days with a liquid medium obtained by removing agar from a plate agar medium for screening as an enzyme-producing medium, to obtain a centrifugal supernatant of the culture solution. The presence or absence of xylan-degrading activity in the supernatant was examined by the above-mentioned simple method under the conditions of pH 7 and 50 ° C. and used as an enzyme solution.

Rice straw having a dry weight of 100 g was cut into a length of 5 cm, immersed in 16.5 l of a 10% by weight NaOH aqueous solution, and kept at room temperature all day and night. After that, take out the rice straw,
It was washed well with water to remove NaOH, eluate and adhering matter such as mud, and centrifugally dehydrated to obtain a pretreated raw material. Next, water was added to this pretreated raw material so as to be 5% by weight to adjust the pH to 7
Adjusted to. As the enzyme, a culture supernatant of the above microorganism was used.
10% by weight based on the dry weight of straw against rice was added, and the mixture was kept at 50 ° C. and reacted for 72 hours while gently stirring. After the reaction,
The rice straw was taken out and dissociated with a pulper, and then sieved with a flat screen (manufactured by Kumagai Riki Kogyo Co., Ltd.) to obtain pulp.

PFI mill (Kumagaya Riki Kogyo Co., Ltd.)
Manufactured), clearance 0.5 mm, beating pressure 1.8
After beating to a Canadian standard freeness (CSF) of 200 ml at kgf / cm and a pulp concentration of 10%, JIS P82
When the handmade paper was prepared according to the method for preparing the handmade paper for 09 pulp test, good rice straw pulp handmade paper was obtained.
According to JIS P8113 and JIS P8116, the tear length and the specific tear strength of this handmade paper were obtained. The results are shown in Table 1.
Shown in

Comparative Example 1 The same operation as in Example 1 was carried out by using the microorganisms (strain D, strain E) which did not form a clear zone on the plate agar medium in the screening in Example 1,
As shown in Table 1, rice straw could not be pulped.

[0027]

[Table 1]

Example 2 Rice straw having a dry weight of 100 g was cut into a length of 5 cm and washed well with water to remove impurities adhering to the surface of the rice straw to obtain a pretreated raw material. Next, water was added to the pretreated raw material so as to be 5% by weight to adjust the pH to 5. A commercially available xylanase preparation (SIGMA) was added as an enzyme in an amount of 1% by weight based on the dry weight of rice straw, and the mixture was kept at 50 ° C. and allowed to stand for 10 days for reaction. After the reaction, the rice straw was taken out and separated by a pulper, and then flat screen (Kumagaya Riki Kogyo Co., Ltd.)
The product was screened to obtain pulp.

JIS P8 without beating it
When the handmade paper was prepared according to the method for preparing the handmade paper for the 209 pulp test, good rice straw pulp handmade paper was obtained.

Comparative Example 2 When the same operation as in Example 2 was carried out except that the enzyme treatment was performed, rice straw could not be disintegrated with pulper and pulped.

Example 3 Straw having a dry weight of 500 g was cut into a length of 5 cm, and then 10
It was dipped in 16.5 l of an aqueous solution of NaOH with a concentration by weight of 1% and kept at room temperature for one day. After that, the rice straw was taken out, washed thoroughly with water to remove adhered substances such as NaOH, eluate and mud, and centrifugally dehydrated to obtain a pretreated raw material. Next, water was added to the pretreated raw material so as to be 3% by weight, and the pH was adjusted to 6. A commercially available hemicellulase preparation (Amano Pharmaceutical Co., Ltd.) was added in an amount of 1% by weight based on the dry weight of rice straw, and the mixture was kept at 40 ° C. and reacted for 48 hours while gently stirring. After the reaction, the rice straw was taken out, disintegrated with a pulper, and then sieved with a flat screen (manufactured by Kumagai Riki Kogyo Co., Ltd.) to obtain pulp.

After beating with a Niagara beater (manufactured by Kumagai Riki Kogyo Co., Ltd.) up to 300 ml at Canadian standard freeness, the basis weight was adjusted to 125 g / m ² according to the method for preparing handsheets for JIS P8209 pulp test. When handmade paper was prepared, good straw paper was obtained. JIS P8
The tear length and specific compressive strength of the obtained handmade paper were obtained according to 113 and JIS P8126. Breaking length is 10.
1, the specific compressive strength was 14.3. This value is JIS
The specified value of corrugated cardboard shin shown in P3904 is satisfied.

Comparative Example 3 When the same operation as in Example 3 was carried out except that the enzyme treatment was performed, rice straw could not be disintegrated with pulper and pulped.

Example 4 Rice straw having a dry weight of 1000 g was immersed in 33.3 l of a 1 wt% NaOH aqueous solution for 0.5 hours, and then clearance 1 was applied.
It was lightly defibrated with a disc refiner (manufactured by Kumagai Riki Kogyo Co., Ltd.) under the condition of mm. After that, take out the rice straw,
It was washed well with water to remove NaOH, eluate and adhering matter such as mud, and centrifugally dehydrated to obtain a pretreated raw material. Next, water is added to the pretreated raw material so that the content of the pretreated raw material becomes 10 wt%,
Adjusted to 5. Commercially available xylanase preparation (SI
GMA) was added in an amount of 0.05% by weight based on the dry weight of rice straw, and the mixture was stirred well and allowed to stand at 50 ° C for 8 hours for reaction.
After the reaction, the rice straw was taken out, disintegrated with a pulper, and then sieved with a flat screen (manufactured by Kumagai Riki Kogyo Co., Ltd.) to obtain pulp.

Niagara beater (Kumagaya Riki Kogyo)
200 ml with Canadian Standard Freeness (CSF)
After beating up to, JIS P8209 pulp test hand
When the handmade paper was prepared according to the paper making method, it was good.
A rice straw pulp handmade paper was obtained. JIS P8113
And according to JIS P8116, the tearing length of this handmade paper and
The specific tear strength was calculated to be 8.5 and 9.
It was 8. Comparative Example 4

When the same operation as in Example 4 was carried out except that the enzyme treatment was performed, rice straw could not be pulped.

Example 5 Using the PFI mill (manufactured by Kumagai Riki Kogyo Co., Ltd.), the rice straw pulp prepared in Example 4 was subjected to a clearance of 0.5 mm, a beating pressure of 1.8 kgf / cm and a pulp concentration of 10%. Beat up,
A Canadian Standard Freeness (CSF) 320 ml stock was obtained.

C obtained by beating commercially available hardwood BKP with a PFI mill (manufactured by Kumagai Riki Kogyo Co., Ltd.) under the same conditions as above.
SF 560 ml of stock material is mixed with 70 of rice straw pulp stock material in a ratio of 30 to obtain JIS P820.
9 When the handmade paper was prepared according to the method for preparing handmade paper for pulp test, good rice straw handmade paper was obtained.
According to JIS P8113 and JIS P8119, the breaking length and the smoothness of this handmade paper were determined to be 4.5 and 65, respectively.

Comparative Example 5 Commercial hardwood BK without blending paper stock from rice straw pulp
A handsheet was prepared by the method described in Example 5 using only the paper material from P, and the breaking length and smoothness were determined to be 4.0.
And 40.

[0040]

EFFECTS OF THE INVENTION According to the present invention, agricultural wastes such as rice straw, wheat straw, and bagasse that have not been effectively used until now without producing a large amount of waste liquid which leads to environmental damage, which is a drawback of the conventional method. Pulp can be efficiently produced from non-wood resources represented by products. The pulp thus produced can be made into paper or paperboard by papermaking according to a standard method, and when it is mixed with wood pulp to make paper, it has high paper strength and a well-textured surface.・ Can make paperboard.

Claims (7)

[Claims] 1. A method for producing pulp, which comprises treating a fiber source derived from a non-wood plant with an enzyme having a xylan-decomposing activity. 2. The method for producing pulp according to claim 1, wherein the fiber source is agricultural waste. 3. The method for producing pulp according to claim 1, wherein the non-woody plant is a monocot. 4. The method for producing pulp according to claim 1, wherein the fiber source derived from a non-wood plant is rice straw, wheat straw, bagasse, corn cob, cottonseed meal or oat seed coat. 5. After the processing according to claims 1 to 4,
A method for producing pulp, which comprises subjecting the obtained pulp to reduction bleaching and / or oxidative bleaching. 6. After the processing according to claims 1 to 5,
A method for producing paper / paperboard, which comprises filtering the obtained pulp. 7. After the processing according to claims 1 to 5,
A method for producing paper / paperboard, which comprises blending the obtained pulp with chemical pulp and straining.