JP2006076917A - Method for dissolving by-product remaining after recovery of saccharide from cellulose containing substance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for effectively utilizing the residue that is obtained as a by-product, when saccharides are recovered from cellulose-including substance. <P>SOLUTION: The residue that is obtained as a by-product, when saccharides are recovered from cellulose-containing substances, is heat-treated in an aqueous alkali solution having a concentration of 0.01 to 5 mol/L at a temperature of 100 to 300°C to obtain the residual solution. The residual solution produced by the method according to this invention is coated to obtain reinforced paper. Thereby the residue that is obtained as a by-product, when saccharides are recovered from cellulose-containing substances, becomes handleable as an aqueous solution and the use of the residue can be expanded, for example, as a paper durability enhancer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for dissolving a residue by-produced when sugar is recovered from a cellulose-containing substance and use of the solution.

  Conventionally, fine fibers, paper powder, and the like that are by-produced in the papermaking process are often incinerated or become industrial waste, and it is required to effectively use them. In addition to this, it is also required to effectively use natural products and additives contained in industrial waste, agricultural / forestry waste, and household waste. Among these, when effectively using cellulose-containing wastes such as paper, wood, straw, and other natural polymers containing cellulose, waste paper, wood flour, etc. A method similar to the effective use of waste in the process can be applied.

  As an effective utilization method, for example, as in the method described in Patent Document 1, the above-described cellulose-containing waste is decomposed into sugars with an acid to produce a useful substance such as ethanol by using it as a fermentation raw material. Such a method has been tried. However, after decomposition of these cellulose-containing wastes, a large amount of residues containing lignin, inorganic substances, etc. are by-produced, and its effective use is a process of obtaining useful substances from the above-mentioned cellulose-containing wastes in addition to waste reduction. This is an important issue for making the economy economically viable.

Japanese Patent Laid-Open No. 11-506934

  However, the residue generated after the decomposition of the cellulose-containing waste, particularly the residue by-produced by acid hydrolysis, has extremely low solubility due to the occurrence of a reaction such as crosslinking of lignin contained during decomposition. Among them, the residue obtained when acid hydrolysis is performed using sulfuric acid has a lower solubility.

  Moreover, although the said residue is collect | recovered in large quantities, if this is processed as it is as a fuel for incineration as it is, it cannot be said that the effective utilization of the said cellulose containing waste was fully made. Furthermore, in order to industrialize the process of recovering saccharides from cellulose-containing substances, it is not economical unless this is also effectively utilized. However, these residues, particularly when cellulose-containing waste is decomposed by acid hydrolysis, hardly dissolves, so the effective use is extremely limited and it may be necessary to use fuel for incineration. There were many.

  Accordingly, an object of the present invention is to provide a means for effectively using a residue produced as a by-product when recovering a saccharide from a cellulose-containing substance.

  The present invention provides a solution obtained by heat-treating a residue by-produced when recovering saccharides from a cellulose-containing substance in an alkaline aqueous solution having an effective concentration of 0.01 to 5 mol / L in a temperature environment of 100 to 300 ° C. This solves the above-mentioned problem.

  Residues with low solubility, which are produced as a by-product when recovering saccharides from cellulose-containing substances, can be handled as aqueous solutions, greatly expanding the application range. For example, a paper strength enhancing effect can be obtained by coating paper as an aqueous solution. In addition, the reactivity of the modified lignin such as acid lignin contained in the residue is improved, so that the application range is expanded and other utilization methods can be expected.

The present invention will be described in detail below.
In this invention, the residue by-produced when recovering saccharides from a cellulose-containing substance is heat-treated in an alkaline aqueous solution having an effective concentration of 0.01 to 5 mol / L in a temperature environment of 100 to 300 ° C. This is a method for obtaining a residue solution.

  Examples of the cellulose-containing substance include plants such as conifers, hardwoods, and vegetation, and substances containing lignin such as pulp, waste paper, paper powder, fine fibers, wood powder, corn core, bagasse, sawdust, and straw.

  Recovering the saccharide refers to decomposing and recovering the cellulose contained in the cellulose-containing substance into saccharides by hydrolysis, enzymatic decomposition, thermal decomposition by pressurized hot water treatment, or the like. . In addition, before producing saccharides from these cellulose-containing substances, the cellulose-containing substance is subjected to mechanical or chemical pretreatment such as pulverization and deinking, if necessary, directly, or The slurry is supplied to a continuous device such as a kneader, a semi-continuous device that is filled in a column or the like and passed through, or a batch-type device such as a reaction (fermentation) kettle, and then decomposed into the following saccharides.

  As a method for hydrolyzing the cellulose-containing substance, for example, there is an acid hydrolysis method in which treatment is performed with an acid. As this acid hydrolysis method, for example, the Scholar method, the Madison method, the improved Madison method, the Soviet method, etc., the dilute acid method, the Peoria method, the Giordani-Leone method, the Hokkaido method, the Soviet method, the Bergius Reinau method, the new method Examples thereof include concentrated acid methods such as the Reinau method, the Brodle method, the double orphen method, the Elan method, and the Noguchi laboratory method. As the acid used in the above treatment, organic acids such as acetic acid, formic acid and trifluoroacetic acid, and inorganic acids such as sulfurous acid, phosphoric acid, hydrogen fluoride, sulfuric acid, nitric acid and hydrochloric acid are used, and sulfuric acid and hydrochloric acid are particularly preferable.

  Examples of the decomposition treatment method of the cellulose-containing substance other than the acid hydrolysis include enzymatic decomposition and pressurized hot water treatment.

  The above enzymatic degradation includes C1 enzyme (also referred to as avicellase, cellobiohydrase, FPase, exo-β-glucanase, etc.), Cx enzyme (also referred to as CMCase, endo-β-glucanase) and β. -Cellulase called by various names such as glucosidase (also called cellobiase) is allowed to act on the cellulose-containing substance in a water suspension under known conditions. The origin of the enzyme is not particularly limited, and examples thereof include Trichoderma reesei, Trichoderma viride, Aspergillus genus and Penicillium genus.

  The pressurized hot water treatment is usually performed at a temperature of 180 to 600 ° C. and a pressure of 5 to 50 MPa by the method of decomposing the cellulose-containing substance in high-temperature / high-pressure water, subcritical water or supercritical water.

  By treating the cellulose-containing substance as described above, an active ingredient composed of a sugar such as a monosaccharide or an oligosaccharide is obtained, and at the same time, a by-product is generated. By-products that remain as residues when recovering this sugar vary depending on the raw material origin, processing method, etc., but include organic substances such as lignins, proteins, and carbohydrates, and inorganic substances such as salts, minerals, acids, and silica compounds. . In particular, the residue obtained by acid hydrolysis contains a large amount of acid lignin different from ordinary lignin, such as sulfate lignin and lignin hydrochloride. Among them, the lignin sulfate using sulfuric acid in the acid treatment has a low reactivity and is difficult to apply to other treatment methods, so this invention is particularly effective. The lignins include not only ordinary lignin but also the acid lignin.

  As the residue to be dissolved in the present invention, the residue remaining when the above sugar is recovered may be used as it is, or before the heat treatment with the above alkaline aqueous solution, washing, pH adjustment, pulverization, drying, fractionation, etc. You may have done.

  As a specific method according to the present invention, for example, the above residue is mixed and immersed in the alkaline aqueous solution to form a slurry, and then heated under the above temperature conditions. Moreover, you may add quinones, such as sodium sulfite, sodium sulfide, polysulfide, methanol, anthraquinone, etc. to said alkaline aqueous solution as an additive.

  As the alkaline aqueous solution for treating the residue in the present invention, a common alkaline reagent may be used, for example, an alkali metal hydroxide compound such as sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate. Basicity such as alkali metal compounds showing basicity such as alkali metal carbonates such as alkaline carbonates, alkaline earth metal compounds such as calcium hydroxide and magnesium hydroxide, alkaline earth metal carbonates such as calcium carbonate and magnesium carbonate Examples thereof include alkaline earth metal compounds shown, and aminos showing basicity such as ammonia, trimethylamine, and triethylamine. Among these, alkali metal hydroxide compounds showing strong basicity are desirable, and sodium hydroxide and potassium hydroxide are particularly desirable.

  The concentration of the alkaline aqueous solution is desirably 0.01 to 5 mol / L as an active ingredient, and more desirably 0.1 to 2 mol / L. If it is less than 0.01 mol / L, the lignin component in the residue, particularly acid lignin, is not sufficiently cleaved, so that the resulting residue has a low dissolution rate. On the other hand, if the concentration exceeds 5 mol / L, decomposition is not hindered, but labor and processing costs required for the treatment after the reaction of the alkaline aqueous solution used are excessive. However, if the residue contains an acidic component such as sulfuric acid, hydrochloric acid, aluminum sulfate, or a substance that generates an acidic substance by decomposing or modifying under the present reaction conditions, such as a saccharide, These acidic components, substances that produce acidic substances, and an equivalent amount of alkali must be added for neutralization. In addition, said effective density | concentration is a density | concentration except the part required for this neutralization.

  The addition amount of the alkaline aqueous solution with respect to the residue needs to be an amount in which the residue to be added is immersed and becomes a slurry, and is preferably 3 to 250 parts by weight with respect to the residue. Part is more desirable. If the alkaline aqueous solution is less than 3 parts by weight, the residue may not be sufficiently immersed and the reaction and dissolution may become non-uniform. On the other hand, when the alkaline aqueous solution is added in excess of 250 parts by weight, the concentration of the substrate in the solution may become too low, and a concentration step may be required. Also, the labor required for the treatment of the alkaline aqueous solution after use, In addition, the processing cost is excessive.

  The reaction / dissolution temperature when the residue is heat-treated with the alkaline aqueous solution needs to be 100 to 300 ° C, and more preferably 140 to 250 ° C. If the temperature is lower than 100 ° C., the dissolution rate is low. On the other hand, if the temperature exceeds 300 ° C., there is a risk that side reactions such as over-decomposition and oxidation that reduce the molecular weight of useful polymers such as lignins are likely to occur. .

  The reaction pressure when the residue is heat-treated with the alkaline aqueous solution needs to be equal to or higher than normal pressure because the reaction / dissolution temperature is equal to or higher than the boiling point of water at normal pressure.

  The treatment time when the residue is heat-treated with the alkaline aqueous solution varies depending on the alkaline aqueous solution concentration and the reaction temperature, and it is difficult to uniformly define, for example, the alkaline aqueous solution concentration as described above. Is 0.01 to 5 mol / L and the reaction temperature is in the range of 100 to 300 ° C., the reaction is usually completed in 30 seconds to 24 hours, and the reaction is completed in 1 minute to 4 hours under more desirable conditions. finish. When the treatment time is extremely short, it is difficult to control the reaction time particularly in the case of a batch type, and in the case of a continuous type, it is difficult to obtain a high dissolution rate although it can be controlled.

  The atmosphere of the reactor for performing the heat treatment is not particularly limited, and the heat treatment may be performed by substituting with a gas such as nitrogen, helium, argon, or ammonia in addition to air. Oxidation can be prevented to some extent by substituting these gases.

  The above apparatus may be any apparatus that can perform heat treatment under the above reaction conditions, for example, a batch type such as an autoclave and a kneader, a continuous type such as a screw kneader and a flow type reaction apparatus, and the above residue as a column. And semi-continuous type in which the alkaline aqueous solution is passed.

  By the treatment as described above, it is considered that reactions such as cleavage and decomposition of β-aryl ether bonds of lignins such as acid lignin contained in the residue, molecular weight reduction, phenolic hydroxyl group increase, Lignins that are sparingly soluble or insoluble change to soluble. In particular, even hardly soluble lignin sulfate and Klason lignin are dissolved almost quantitatively by carrying out under appropriate conditions. In addition, depending on the type of raw material and dissolution conditions, the above lignins are dissolved, and at the same time, inorganic substances such as organic substances, salts, minerals, and silica compounds are dissolved to some extent.

  As described above, an additive may be added to the alkaline aqueous solution used in the present invention, and examples thereof include quinones such as sodium sulfite, sodium sulfide, polysulfide, methanol, and anthraquinone. The addition amount is preferably 0.01 to 2 mol / L. Additives are added depending on the purpose. For example, when sodium sulfite is added, a sulfonic acid group is introduced into the solubilized lignin, and as a result, a solution that is neutral and does not easily precipitate is prepared. Is possible. Moreover, the addition of sodium sulfide improves the dissolution rate.

Of the above residues used, the solubilization rate, which is the rate of change to soluble components, is desirably 30% by weight or more, more desirably 80% by weight or more, and most desirably 100% by weight. In addition, the solubilization rate here is calculated | required by following formula (1) from the dry weight i of the component which remains insoluble after the said heat processing, and the dry weight W of the said residue used.
Solubilization rate = (W−i) / W × 100 (1)

  After performing the above heat treatment, the obtained reaction solution may be used as it is as a residue solution according to the present invention, or may be filtered, centrifuged, neutralized, pH adjusted, ion exchange, re-exchanged according to the purpose of use. Treatments such as crystallization, precipitation, fractionation, dialysis, solvent extraction, decolorization, and deodorization may be performed. However, since the above-mentioned soluble acid lignin may precipitate when it changes from neutral to acidic, it is desirable to maintain alkalinity. However, when sodium sulfite or the like is added to the alkaline aqueous solution as described above, precipitation in the acidic region is suppressed due to weak alkalinity.

  The molecular weight range of (denatured) lignin in the soluble component in the residue solution obtained by the present invention is determined by gel permeation chromatography (hereinafter referred to as “GPC”) as the eluent (1,4-dioxane: water = (A solution in which NaCl is dissolved in a solution of 1: 1 so as to have a concentration of 0.5 mol / L) The number average molecular weight measured by dissolving a sample of 1 mg in 2 ml and filtering through a filter is preferably 300 to 30,000.

  Examples of the use of the residue solution obtained by the present invention include a paper strength enhancer. When used as a paper strength enhancer, the effect of improving the compressive strength and tensile strength can be obtained.

  As a usage form when used as the paper strength enhancer, the residue solution obtained by treating the residue with the alkaline aqueous solution may be directly applied to paper as it is, pH adjustment, You may apply what performed processes, such as concentration, insoluble matter removal, solvent extraction, molecular weight fractionation, and removal of the volatile material by pressure reduction. In addition, coating includes application, spraying, and dipping, and the above coating indicates an action such as painting with a brush, a coating machine, a size press, etc., and the above spraying indicates an action such as spraying with a spray, etc. The above immersion refers to an act of wetting with a solution or submerging in a solution.

  In addition, when the residue solution obtained from the present invention is used as a paper strength enhancer, in addition to using the paper strength enhancer alone, other paper additives and / or fillers are added and used. Also good.

  Examples of the above paper additive include polyacrylamide, polyvinyl alcohol, polyvinylamine, styrene acrylic resin, polyamide polyamine epichlorohydrin resin, melamine resin, urea resin, ketone resin, and other natural resins such as starch and guar gum. Polymer, cationic modified starch, acetylated starch, modified starch such as urea phosphated starch, cellulosic polymer such as CMC, oligosaccharide such as starch sugar, cellobiose, maltose, zirconium compound, silicic acid compound, polyhydric alcohol / Crosslinking agents such as carbonyl compounds, cyclic amide compounds, glyoxal, and aluminum sulfate.

  Of these, as saccharides obtained by decomposition of the cellulose-containing substance that is a by-product of the residue used in the present invention, as cellulose-based polymers and oligosaccharides, useful components obtained from the cellulose-containing substance are collectively collected. Can be used for recycling.

  Examples of the filler include kaolin, talc, calcium carbonate, titanium oxide, zinc oxide, silica, magnesium carbonate, and magnesium hydroxide.

  Examples of the paper include paper, corrugated cardboard such as liner and core, white paperboard, paperboard board such as chipball, and paper tube base paper.

  The paper strength enhancer using the residue solution obtained by the present invention is presumed that lignin-derived substances, polyvalent metal ions, silica compounds and the like contained therein are involved in paper strength enhancement, and particularly lignin. Since the derived material has lignin as a basic skeleton that originally functions as an adhesive for cellulose in wood, it has excellent affinity and interaction with paper. Therefore, among the paper strength enhancing effects, it is possible to produce a reinforced paper that exhibits a stronger compressive strength and tensile strength enhancing effect. In addition, since the acid lignin, which has been difficult to use effectively so far, is also effectively used, it has a high environmental effect and is economical.

  In addition to the paper strength enhancer described above, the residue solution obtained by the present invention is, for example, a dispersant, a concrete water reducing agent, a granulating agent, an agrochemical, a soil improver, a binder, a binder, an emulsion stabilizer, Complex salt forming agent, precipitant, antioxidant, dye, pigment, muddy water conditioner, water treatment agent, adhesive, synthetic resin, preservative, growth promoter, additive for gypsum board, additive for foundry sand, deinking Agents, fireproofing agents, waterproofing agents, dimensional stabilizers, weathering agents, pollution control agents, leather glazes, rubber additives, and the like. Moreover, since the soluble component derived from lignin is highly reactive and water-soluble, it can be used as a raw material for further lignin derivatives such as lignin sulfonic acid and cationic lignin.

  Hereinafter, the present invention will be specifically described with reference to examples. First, it measures about the solubilization rate of the various residue which changed the manufacturing method, and then measures the paper strength intensity | strength at the time of applying a residue solution.

[Solubilization rate and number average molecular weight]
(Method for preparing residue by acid hydrolysis (1))
First, a method for preparing a residue used in this example will be described. Add 2250 ml of 72 wt% sulfuric acid (manufactured by Nacalai Tesque Co., Ltd .: GR) to 300 g of defibrated newspaper base paper, leave it at 25 ° C. for 3 hours, add 1500 mL of water, and filter through a glass filter (G1). After sufficiently washing with water, 387 g of an undried residue was recovered. The undried residue was pulverized with a ball mill (manufactured by Fritsch Japan Co., Ltd .: centrifugal ball mill) and then vacuum-dried in an environment of 60 ° C. to obtain 57 g of dark brown residue (ash content: 16% by weight) containing lignin sulfate. . In addition, said ash content is inorganic components, such as a silica, aluminum, calcium, magnesium contained in a sample, and let the residual weight after processing a sample for 4 hours at 775 degreeC here be the weight of ash content.

Example 1
1.0 g of the residue prepared by the above method and 50 ml of 1 mol / L NaOH (manufactured by Nacalai Tesque, Inc .: GR) solution were charged into a pressure vessel and reacted at 180 ° C. for 4 hours. Thereafter, the supernatant was recovered by centrifugation (8000 rpm, 20 min) to obtain a residue solution containing soluble lignin sulfate. When this solution was subjected to GPC measurement under the following conditions, the number average molecular weight (Mn) of the dissolved component was 4,500. In addition, after thoroughly washing the insoluble residue, which is the remaining recovered supernatant, it was dried under reduced pressure at 80 ° C. and 15 mmHg for 1 hour. The recovered insoluble component was 0.19 g, and the above formula (1) The solubilization rate of the residue was calculated by 81, and it was 81% by weight. Furthermore, when 1N sulfuric acid was added to the residue solution to adjust the pH to 7, precipitation occurred.

<GPC measurement conditions>
Column: Tosoh Corporation Manufacturing: α-3000 (6.0 mm ID × 4.0 cm)
Eluent: 1,4-dioxane / water = 1/1 (0.5M NaCl)
・ Flow rate: 0.5mL / min
・ Oven temperature: 40.0 ℃
・ Detector: UV (280 nm)

(Example 2)
50 ml of the residue solution obtained by the procedure of Example 1 was placed in a dialysis tube (manufactured by Viscose Sales: UC36-32-100) and dialyzed for one week in distilled water. Thereafter, the aqueous solution remaining in the tube was freeze-dried to obtain 0.5 g of a soluble residue which is a dark brown powder. When this soluble residue was subjected to GPC measurement by the same procedure as in Example 1, the number average molecular weight was 5,500.

(Examples 3 to 12)
A residue solution was obtained by the same procedure as in Example 1 except that the reaction temperature, sodium hydroxide aqueous solution concentration, reaction time, and residue addition amount were changed as shown in Table 1 below, and the solubilization rate was calculated. The results are shown in Table 1.

(Comparative Example 1: Reaction at low temperature)
A residue solution was obtained by the same procedure as in Example 1 except that the reaction temperature was 80 ° C., and the solubilization rate was calculated. The results are shown in Table 1.

(Comparative Example 2: Reaction at high temperature)
Except that the reaction temperature was 320 ° C., a black solution with a bad odor was obtained in the same procedure as in Example 1. Then, when it processed with the dialysis tube similarly to Example 2, the collect | recovered soluble residues were 0.1g. It is thought that it decreased due to excessive decomposition due to high temperature.

(Comparative Example 3: Reaction at low alkali concentration)
A residue solution was obtained by the same procedure as in Example 1 except that the NaOH concentration was 0.005 mol / L, and the solubilization rate was calculated. The results are shown in Table 1.

(result)
According to the method of the present invention, 30% by weight or more of the residue containing lignin sulfate could be solubilized, and 90% by weight or more of the residue could be solubilized depending on conditions.

[Changes due to differences in materials and reagents]
(Example 13)
A residue solution was obtained by the same procedure as in Example 1 except that 1 mol / L KOH (manufactured by Nacalai Tesque Co., Ltd .: GR) was used instead of the 1 mol / L NaOH aqueous solution, and the solubilization rate was calculated. As a result, it was 96 weight%.

(Example 14)
In the above-mentioned residue preparation method (1) by acid hydrolysis, 42 wt% hydrochloric acid is used in place of sulfuric acid, and lignin hydrochloride is prepared by the same procedure as the above-mentioned residue preparation method containing lignin sulfate at 1 to 5 ° C. As a result, 55 g (ash content = 14% by weight) of a dark brown residue was obtained. A residue solution was obtained from 1.0 g of the residue obtained above by the same procedure as in Example 1. The insoluble residue was washed with water and dried, and 0.1 g of a light brown solid was obtained. The solubilization rate calculated by the above formula (1) was 90% by weight.

(Example 15)
A residue solution was obtained in the same manner as in Example 6 (reaction time 6 hours, solubilization rate 70% by weight) except that 1.0 g of sodium sulfide (manufactured by Nacalai Tesque Co., Ltd .: GR) was added during the reaction. The solubilization rate was calculated to be 83% by weight, which was close to Example 7 (solubilization rate 85% by weight) multiplied by 8 hours, and the reaction time could be shortened.

(Method for preparing residue by acid hydrolysis (2))
In the preparation of the residue by acid hydrolysis, after adding 1500 mL of 72 wt% sulfuric acid (manufactured by Nacalai Tesque, Inc .: GR) to 200 g of wood (cedar sawdust, manufactured by Kunitake Sawmill) as a raw material, the mixture was allowed to stand at 25 ° C. for 3 hours. The solution was filtered through a glass filter (G1) to recover an undried residue. The undried residue was dispersed in 6.8 L of 3 wt% sulfuric acid, treated at 121 ° C. for 90 minutes, filtered through a glass filter (G1), washed thoroughly with water, and the residue was vacuum dried at 80 ° C. to obtain Klason lignin. As a result, 63 g (ash content: 0.1% by weight) of a dark brown residue was obtained.

(Example 16)
A residue solution was obtained in the same manner as in Example 1 except that 5.0 g of the above residue and 250 ml of 0.1 mol / L NaOH aqueous solution were charged in a pressure vessel and reacted at 230 ° C. and 2.6 MPa for 2 hours. The solubilization rate was 99% by weight.

(Example 17)
A residue solution was obtained in the same manner as in Example 16 except that 5.0 g of sodium sulfite (manufactured by Nacalai Tesque Co., Ltd .: GR) was added during the reaction, and the solubilization rate was calculated to be 99% by weight. It was. Even when this solution was adjusted to pH = 7 with 1N sulfuric acid, no precipitate was observed.

(Method for preparing residue by acid hydrolysis (3))
In the preparation of the residue by acid hydrolysis, 900 mL of 72 wt% sulfuric acid (manufactured by Nacalai Tesque Co., Ltd .: GR) is added to 300 g of a core for corrugated board (basis weight: 115 g / m ² ) as a raw material. , Left at 30 ° C. for 2 hours, added 450 mL of distilled water, filtered through a glass filter (G1), washed with 1.5 L of distilled water, and 228 g of dark brown undried residue containing lignin sulfate (water content: 73.4 wt. %, Sulfuric acid content 2.2 wt%, ash content 8.8 wt%).

(Example 18)
Distilled water (70 mL) was dispersed in 41 g of the above residue, neutralized with 0.7 g of NaOH (Nacalai Tesque, Inc .: GR), added with 3.0 g of NaOH, charged into a pressure vessel, 220 ° C., 2.2 MPa for 4 hours. Except for making it react, it carried out like Example 1 and obtained the residue solution, and it was 65 weight%, when the solubilization rate was computed.

(Method for preparing residues by enzymatic decomposition)
20 g of defibrated cardboard waste paper is divided into 2 g portions in a beaker, each is added to 100 mL of 20 mM acetate buffer (pH 4.5), pulverized for 10 min with a homogenizer (manufactured by Nippon Seiki Co., Ltd .: bio-mixer BM-1), Collectively, the mixture was filtered through a glass filter (G1) to obtain a filter residue. The flask is charged with the above residue, 400 mL of 20 mM acetate buffer (pH 4.5), and 0.8 g of cellulase (Cellulosin T2, manufactured by HI Corporation), shaken at 45 ° C. and 90 spm for 48 hours, and then added at 90 ° C. for 30 minutes. The enzyme was deactivated by warming. The enzyme treatment solution was filtered through a glass filter (G1), washed thoroughly with water, and the residue was vacuum dried at 80 ° C. to obtain 13 g of a residue (cellulose content: 74% by weight, ash content: 13% by weight).

(Example 19)
Dissolve the residue in the same manner as in Example 1 except that 7.0 g of the residue prepared above and 50 ml of 2 mol / L NaOH aqueous solution were charged in a pressure vessel and reacted at 220 ° C. and 2.2 MPa for 4 hours. The solution was obtained, and the solubilization rate was calculated to be 88% by weight.

(Method for preparing residue with pressurized hot water)
10 g of wood (cedar sawdust, manufactured by Kunitake Sawmill) and 90 mL of distilled water were charged into a pressure vessel, treated in a 270 ° C. silicon bath at 15 MPa for 20 minutes, and then rapidly cooled to room temperature. The treated product was filtered through a glass filter (G1), sufficiently washed with water, and the residue was vacuum dried at 80 ° C. to obtain 4 g of a residue (cellulose content 35% by weight, ash content 0.1% by weight).

(Example 20)
A residue solution was prepared in the same manner as in Example 1 except that 1.0 g of the residue prepared as described above and 50 ml of 1 mol / L NaOH aqueous solution were charged in a pressure vessel and reacted at 220 ° C. and 2.2 MPa for 3 hours. Obtained and calculated solubilization rate was 85 wt%.

[Paper strength enhancement effect]
(Examples 21 to 25)
To the solution prepared as described below, the residue solution obtained in Examples 1, 9, 16, 17, and 18 was used as a corrugated core (made by Rengo Co., Ltd., basis weight: 115 g / m ² , 15 cm × 15 cm). ) Is soaked for 30 seconds, the core is pulled up and the solution adhering to the suction filter paper is sucked off, and then subjected to a rotary drier (manufactured by JAPO: Auto Dryer Type L-3D 120 ° C., drying time: 90 seconds). In this way, a residue-dissolving solution coating core was obtained. This was conditioned at 23 ° C. and 50% humidity for 24 hours, and then evaluated by the following method. The results are shown in Table 2.

Example 21: The residue solution obtained in Example 1 is used as it is as a coating solution.
Example 22: The residue solution obtained in Example 9 was concentrated under reduced pressure to a solute concentration of 5% by weight, adjusted to pH 10 with sulfuric acid, and used.
Example 23: The residue solution obtained in Example 16 was concentrated under reduced pressure to a solute concentration of 5% by weight, adjusted to pH 10 with sulfuric acid, and used.
Example 24: The residue solution obtained in Example 17 was concentrated under reduced pressure to a solute concentration of 5% by weight, adjusted to pH 10 with sulfuric acid, and used.
Example 25: The residue solution obtained in Example 18 was diluted with distilled water to a solute concentration of 5% by weight, adjusted to pH 10 with sulfuric acid, and used.

(Coating amount measurement)
After the humidity control of the obtained core, it was dried at 105 ° C. for 5 hours to calculate the absolute dry basis weight, and the coating amount was calculated from the difference from the absolute dry basis weight of the original core used. .

(Measurement of compressive strength and specific compressive strength)
Measured according to JIS P 8126.

(Fracture length measurement)
Measured according to JIS P 8126.

(Example 22)
Instead of immersing in Example 21, the residue solution obtained in Example 1 was conditioned by the same procedure as in Example 21 except that spray coating was applied to the surface of the core at 500 g / m ^2. The same evaluation was performed. The results are shown in Table 2.

(Comparative Example 4)
Evaluation similar to Example 21 was performed about the core for corrugated board (Rengo Co., Ltd. product: Basis weight: 115 g / m < ² >). The results are shown in Table 2.

(result)
The reinforced paper coated with the residue solution according to the present invention is a reinforced paper that is particularly excellent in compressive strength and tensile strength as compared with a normal core.

Claims (5)

  The manufacturing method of the residue solution by heat-processing the residue after collect | recovering saccharides from a cellulose containing substance in 100-300 degreeC environment in the alkaline aqueous solution whose effective density | concentration is 0.01-5 mol / L.   2. The production method according to claim 1, wherein the residue is a residue produced as a by-product when the saccharide is recovered from the cellulose-containing substance by an acid hydrolysis method, an enzymatic decomposition method, or a pressurized hot water decomposition method.   The production method according to claim 2, wherein the acid hydrolysis method is a dilute acid method or a concentrated acid method.   The production method according to any one of claims 1 to 3, wherein 0.01 to 2 mol / L of sodium sulfite or sodium sulfide is added to the alkaline aqueous solution.   Reinforced paper obtained by applying the residue solution produced by the production method according to claim 1.