JP6920260B2 - Cellulose fine fiber-containing material and its manufacturing method - Google Patents

Description

The present invention relates to a cellulose fine fiber-containing compound and their preparation how.

In recent years, nanotechnology has been attracting attention for the purpose of refining substances to the nanometer level so that substances have new physical properties different from conventional properties. Among them, cellulose fine fibers produced from pulp are excellent in strength, elasticity, thermal stability, etc., and also contribute to environmental protection, so their expectations are high and their applications are wide. To give a few examples, for example, industrial applications such as filter media, filter aids, base materials for ion exchangers, fillers for chromatographic analysis equipment, fillers for compounding resins and rubbers, lipsticks, powder cosmetics, etc. , There are applications for blending cosmetics such as emulsified cosmetics. In addition, the cellulose fine fibers also have the property of being excellent in water-based dispersibility. From this property, for example, it is used as a viscosity preservative for foods, cosmetics, paints, etc., a toughener for food raw material dough, a water preservative, a food stabilizer, a low-calorie additive, an emulsion stabilization aid, and the like. It is also expected to be used.

Cellulose fine fibers, which are expected to be used in such various applications, are usually obtained by refining pulp or the like in an aqueous dispersion state. Therefore, the obtained cellulose fine fibers are in an aqueous dispersion state (dispersion liquid). However, when the cellulose fine fibers are in the state of a dispersion liquid, a large amount of transportation energy is required. Therefore, considering commercialization, it is necessary to dry the dispersion liquid of cellulose fine fibers. However, when the cellulose fine fibers are dried, the cellulose fine fibers are strongly aggregated by hydrogen bonds. Therefore, even if the dried cellulose fine fibers are dispersed again in water, there is a problem that the dried cellulose fine fibers are not sufficiently dispersed to the state before drying. Therefore, a technique for improving the dispersibility (redispersibility) of cellulose fine fibers in a dispersion medium such as water is required.

In this regard, for example, Patent Document 1 describes "a step of mixing cellulose nanofibers and a redispersion accelerator to obtain a gel-like substance, and mixing the gel-like substance with an organic liquid compound and a dispersant. A method for producing a cellulose nanofiber dispersion liquid, which includes a step of redispersing cellulose nanofibers, is proposed. However, this proposal does not dry the cellulose fine fibers to a dry state, but merely makes them in the form of a gel. Moreover, this proposal envisions an organic liquid compound as the dispersion medium.

Further, Patent Document 2 proposes "a method for drying bacterial cellulose, which comprises adding a third component other than bacterial cellulose and water to an aqueous suspension containing bacterial cellulose and then dehydrating and drying". There is. However, bacterial cellulose is cellulose produced by microorganisms and has different physical characteristics from cellulose fine fibers obtained by defibrating pulp. Therefore, even if the proposal is diverted to the drying of cellulose fine fibers, the same effect may not always occur.

Further, Patent Document 3 describes, "A first step of adding a compound containing at least one selected from an alkali-soluble metal and a polyvalent metal ion to a fine fibrous cellulose slurry to obtain a fine fibrous cellulose concentrate; and the above-mentioned. A method for producing a fine fibrous cellulose redispersion slurry, which comprises a second step of adding at least one selected from tetraalkylonium hydroxide and alkylamine to the fine fibrous cellulose concentrate: has been proposed. However, according to the proposal, the process of obtaining a concentrate of cellulose fine fibers is complicated. Moreover, since the alcohol solution is used for redispersion, the handleability when using the redispersed dispersion is inferior.

Japanese Unexamined Patent Publication No. 2014-118521 Japanese Unexamined Patent Publication No. 9-165402 Japanese Unexamined Patent Publication No. 2017-52243

The main object of the present invention is to provide is to provide easy manufacturing cellulose fine fiber-containing substance which is excellent in dispersibility in water and its production how.

The means to solve the above problems are
Contains cellulose fibrils and flocculants into which phosphorous acid esters containing cations consisting of inorganic substances have been introduced.
The ratio of cations composed of the inorganic substance to 1 g of the cellulose fine fibers is 0.14 mmol or more.
It is a cellulose fine fiber-containing material.

Further, a dispersion liquid containing cellulose fine fibers is obtained by introducing a phosphite ester into the cellulose fibers and then defibrating the fibers, and an alkali metal ion-containing substance is added to the cellulose fibers in this process. and then, as to obtain a cellulose fine fiber-containing product by concentrating the dispersion liquid, comprising the step of agglomerating the cellulose fine fibers to obtain the cellulose fines content from the dispersion,
This is a method for producing a cellulose fine fiber-containing material.

According to the present invention, an easily manufactured cellulose fine fiber-containing product is excellent in dispersibility in water and its production how.

Next, a mode for carrying out the present invention will be described. The embodiment of the present invention is an example of the present invention.

The cellulose fine fiber-containing material of the present embodiment contains a cellulose fine fiber into which an ester of phosphorous acid containing a cation consisting of an inorganic substance is introduced and a flocculant . Further, in producing the cellulose fine fiber-containing material, a dispersion liquid containing the cellulose fine fiber is obtained by introducing an ester of phosphite into the cellulose fiber and then defibrating the cellulose fiber, and in this process, the cellulose fiber is obtained. alkali metal ion-containing substance shall be added, shall concentrating the dispersion, it is intended to include a step of aggregating the cellulose fine fibers to obtain the cellulose fines content from the dispersion against. Hereinafter, they will be described in order. The addition of the alkali metal ion-containing substance is a step of introducing the phosphite ester or a step performed prior to the introduction step. However, the addition of the alkali metal ion-containing substance can also be performed in, for example, a defibration step, a concentration step, an aggregation step and the like.

(Cellulose fine fiber)
Cellulose fine fibers (hereinafter, also simply referred to as “cellulose fine fibers”) into which an ester of phosphorous acid containing a cation composed of an inorganic substance of this embodiment is introduced are one of the hydroxy groups (-OH groups) of the cellulose fibers. The part is substituted with a functional group represented by the following structural formula (1), and an ester of phosphorous acid containing a cation composed of an inorganic substance is introduced (modified, modified) (esterified). Preferably, a part of the hydroxy group of the cellulose fiber is replaced with a carbamate group, and carbamate (ester of carbamic acid) is also introduced.

In the structural formula (1), α is any of none, R, and NHR. R is a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched chain hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, an unsaturated-branched chain hydrocarbon group. , Aromatic groups, and any of these inducing groups. β is a cation composed of an inorganic substance.

The ester of phosphite is a compound in which a hydroxyl group (hydroxy group) (−OH) and an oxo group (= O) are bonded to a phosphorus atom, and the hydroxyl group gives an acidic proton. Therefore, the ester of phosphorous acid is a kind of oxo acid of phosphorus. Therefore, the ester of phosphorous acid has a high negative charge like the compound having a phosphoric acid group. Therefore, when the ester of phosphorous acid is introduced, the repulsion between the cellulose molecules becomes strong, and the defibration of the cellulose fibers becomes easy. Further, when an ester of phosphorous acid is introduced, the transparency and viscosity of the dispersion are improved. In particular, when carbamate is introduced together with the ester of phosphorous acid, the transparency and viscosity are further improved. In this respect, carbamate has an amino group. Therefore, when carbamate is introduced, it also has a positive charge. Therefore, it is considered that the introduction of carbamate also enhances the charge interaction between the ester of phosphorous acid and carbamate and improves the viscosity. It should be noted that carbamate is more easily introduced when an ester of phosphorous acid is introduced than when a compound having a phosphoric acid group is introduced at the same time.

Further, when the ester of phosphorous acid is introduced, unlike the case where the compound having a phosphoric acid group is introduced, the yellowing of the obtained cellulose fine fibers is prevented. In this respect, the effect of preventing this yellowing change is not the effect obtained by introducing the oxo acid of phosphorus in general, but the effect obtained only by introducing the ester of phosphorous acid. Therefore, the concept of phosphorus oxoacids has no meaning in terms of preventing yellowing. The present inventors have independently discovered that the ester of phosphorous acid has an effect of preventing yellowing.

The present inventors consider that the yellowing is likely to occur when a compound having a phosphoric acid group is introduced because a double bond is likely to occur in cellulose due to the Maillard reaction or the reduction reaction. A compound having a phosphoric acid group has a larger number of hydrogens than an ester of phosphorous acid, so that the pH is lower. The lower the pH, the easier it is for the reaction between the amine and the sugar to occur, or the easier it is for the cellulose to be reduced. Therefore, when an attempt is made to introduce a compound having a phosphoric acid group, cellulose is easily decomposed during heating to produce sugar, or cellulose is easily reduced. As a result, it is considered that the yellowing is more likely to occur when a compound having a phosphoric acid group is introduced.

The amount of phosphorous acid ester introduced is preferably 0.06 to 3.39 mmol, more preferably 0.61 to 1.75 mmol, and particularly preferably 0.95 to 1.42 mmol per 1 g of cellulose fine fibers. If the amount introduced is less than 0.06 mmol, defibration of the cellulose fibers may not be easy. In addition, the aqueous dispersion of cellulose fine fibers may become unstable. On the other hand, if the amount introduced exceeds 3.39 mmol, the cellulose fibers may dissolve in water.

The amount of phosphorous acid ester introduced is a value evaluated based on elemental analysis. For this elemental analysis, X-Max 50001 manufactured by HORIBA, Ltd. is used.

The degree of substitution (DS) of the functional group represented by the structural formula (1) is preferably 0.01 to 0.55, more preferably 0.10 to 0.28, and particularly preferably 0.15 to 0.23. .. If the degree of substitution is less than 0.01, the cellulose fibers may not be easily defibrated. On the other hand, if the degree of substitution exceeds 0.55, the cellulose fibers may turn yellow.

The degree of substitution of the carbamate group is preferably 0.01 to 0.50, more preferably 0.05 to 0.45, and particularly preferably 0.10 to 0.40. If the degree of substitution is less than 0.01, the transparency and viscosity may not be sufficiently increased. On the other hand, if the degree of substitution exceeds 0.50, the cellulose fibers may turn yellow.

The degree of substitution refers to the average number of substitutions of functional groups (functional groups and carbamate groups represented by the structural formula (1)) with respect to one glucose unit in cellulose. The degree of substitution can be controlled, for example, by the reaction temperature or reaction time. Increasing the reaction temperature or increasing the reaction time increases the degree of substitution. However, if the degree of substitution is too high, the degree of polymerization of cellulose is significantly reduced.

The ratio (content rate) of cations composed of inorganic substances to 1 g of cellulose fine fibers is preferably 0.14 mmol or more, more preferably 0.69 mmol or more. If the proportion of cations composed of inorganic substances is less than 0.14 mmol, the redispersibility in water may not be sufficiently increased.

The fiber width of the cellulose fine fibers (average diameter of single fibers) is preferably 1 to 1000 nm, more preferably 2 to 400 nm, and particularly preferably 3 to 100 nm. If the fiber width is less than 1 nm, cellulose may dissolve in water and lose the physical characteristics of cellulose fine fibers, such as strength, rigidity, and dimensional stability. On the other hand, when the fiber width exceeds 1000 nm, it can no longer be said to be a cellulose fine fiber, but a normal cellulose fiber.

The fiber width of the cellulose fine fibers is measured using an electron microscope as follows.
First, 100 ml of an aqueous dispersion of cellulose fine fibers having a solid content concentration of 0.01 to 0.1% by mass is filtered through a membrane filter made of Teflon (registered trademark), and the solvent is once with 100 ml of ethanol and three times with 20 ml of t-butanol. Replace. Next, it is freeze-dried and coated with osmium to prepare a sample. This sample is observed by an electron microscope SEM image at a magnification of 5000 times, 10,000 times, or 30,000 times depending on the width of the constituent fibers. In this observation, two diagonal lines are drawn on the observation image, and three straight lines passing through the intersections of the diagonal lines are arbitrarily drawn. Then, the width of a total of 100 fibers intersecting with these three straight lines is visually measured. The median diameter of this measured value is defined as the fiber width.

The axial ratio (fiber length / fiber width) of the cellulose fine fibers is preferably 3 to 1,000,000, more preferably 6 to 340,000, and particularly preferably 10 to 340,000. If the axial ratio is less than 3, it can no longer be said to be fibrous. On the other hand, if the axial ratio exceeds 1,000,000, the viscosity of the dispersion liquid (slurry) may become too high.

The crystallinity of the cellulose fine fibers is preferably 50 to 100%, more preferably 60 to 90%, and particularly preferably 65 to 85%. If the crystallinity is less than 50%, it may be considered that the strength and heat resistance are insufficient. The crystallinity can be adjusted by, for example, selection of pulp fibers, pretreatment, defibration and the like.

The crystallinity is a value measured by an X-ray diffraction method in accordance with the "general rules for X-ray diffraction analysis" of JIS-K0131 (1996). The cellulose fine fiber has an amorphous portion and a crystalline portion, and the crystallinity means the ratio of the crystalline portion in the entire cellulose fine fiber.

The light transmittance (solid content 0.2% solution) of the cellulose fine fibers is preferably 40.0% or more, more preferably 60.0% or more, and particularly preferably 70.0%. If the light transmittance is less than 40.0%, it may be considered that the transparency is insufficient. The light transmittance of the cellulose fine fibers can be adjusted by, for example, selection of pulp fibers, pretreatment, defibration and the like.

The light transmittance is a value obtained by measuring the transparency (transmittance of 350 to 880 nm light) of a 0.2% (w / v) cellulose fine fiber dispersion liquid using a Spectrophotometer U-2910 (Hitachi, Ltd.).

When the concentration of the cellulose fine fibers is 1% by mass (w / w), the B-type viscosity of the dispersion is preferably 10 to 300,000 cps, more preferably 1,000 to 200,000 cps, and particularly preferably 10, It is 000 to 100,000 cps.

The B-type viscosity is a value measured with respect to an aqueous dispersion of cellulose fine fibers having a solid content concentration of 1% in accordance with "Method for measuring liquid viscosity" of JIS-Z8803 (2011). The B-type viscosity is the resistance torque when the slurry is agitated, and the higher the viscosity, the more energy required for agitation.

(Manufacturing method of cellulose fine fiber)
In the production method of this embodiment, an additive (A) consisting of an alkali metal ion-containing substance and at least one of a phosphorous acid and a metal phosphite salt is added to the cellulose fiber, preferably sodium hydrogen phosphite. Is added and heated to introduce an ester of phosphorous acid containing an inorganic cation into the cellulose fiber. More preferably, an additive (B) consisting of at least one of urea and a urea derivative is also added, and the cellulose fibers are heated to introduce an ester of phosphorous acid containing a cation consisting of an inorganic substance and a carbamate. Cellulose fibers into which an ester of phosphorous acid containing cations composed of an inorganic substance has been introduced are washed and defibrated to obtain cellulose fine fibers.

(Cellulose fiber)
As the cellulose fiber, for example, a plant-derived fiber (plant fiber), an animal-derived fiber, a microorganism-derived fiber, or the like can be used. These fibers can be used alone or in combination, if desired. However, as the cellulose fiber, it is preferable to use a plant fiber, and it is more preferable to use a pulp fiber which is a kind of plant fiber. When the cellulose fiber is a pulp fiber, it is easy to adjust the physical properties of the cellulose fine fiber.

As the plant fiber, for example, wood pulp made from hardwood, softwood, etc., non-wood pulp made from straw, bagas, etc., recovered waste paper, used paper pulp made from waste paper, etc. (DIP), etc. shall be used. Can be done. These fibers can be used alone or in combination of two or more.

As the wood pulp, for example, chemical pulp such as hardwood kraft pulp (LKP) and coniferous kraft pulp (NKP), mechanical pulp (TMP), used paper pulp (DIP) and the like can be used. These pulps can be used alone or in combination of two or more.

The hardwood kraft pulp (LKP) may be hardwood bleached kraft pulp, hardwood unbleached kraft pulp, or hardwood semi-bleached kraft pulp. The softwood kraft pulp (NKP) may be softwood bleached kraft pulp, softwood unbleached kraft pulp, or softwood semi-bleached kraft pulp. The used paper pulp (DIP) may be magazine used paper pulp (MDIP), newspaper used paper pulp (NDIP), stepped used paper pulp (WP), or other used paper pulp.

Cellulose fibers as natural fibers (cellulose fibers before defibration) usually have a fiber width of about 20 to 30 μm. Cellulose fibers having such a fiber width become cellulose fine fibers having a fiber width of 1 μm or less by defibration or the like.

(Alkali metal ion-containing material)
As the alkali metal ion-containing substance, for example, hydroxides, metal sulfates, metal nitrates, metal chloride salts, metal phosphates, metal phosphites, metal carbonates and the like can be used. However, it is preferable to use metal phosphite salts that also serve as the additive (A), and it is more preferable to use sodium hydrogen phosphite. As described above, the addition of the alkali metal ion-containing substance is not limited to the introduction step of the phosphite ester, but is also carried out between each step and each step (for example, a defibration step, a concentration step, an aggregation step, etc. It can also be performed before the ester introduction step; after the phosphite introduction step, before the defibration step; after the defibration step, before the concentration step, etc.).

(Additive (A))
The additive (A) consists of at least one of phosphites and phosphite metal salts. Examples of the additive (A) include phosphite, sodium hydrogen phosphite, ammonium hydrogen phosphite, potassium hydrogen phosphite, sodium dihydrogen phosphite, sodium phosphite, lithium phosphite, and sub-phosphate. Phosphoric acid compounds such as potassium phosphate, magnesium phosphite, calcium phosphite, triethyl phosphite, triphenyl phosphite, and pyrophosphite can be used. Each of these phosphorous acids or phosphorous acid metal salts can be used alone or in combination of two or more. However, it is preferable to use sodium hydrogen phosphate which also serves as an alkali metal ion-containing substance.

In adding the additive (A), the cellulose fibers may be in a dry state, a wet state, or a slurry state. Further, the additive (A) may be in a powder state or an aqueous solution state. However, since the reaction uniformity is high, it is preferable to add the additive (A) in the aqueous solution state to the dry cellulose fibers.

The amount of the additive (A) added is preferably 1 to 10,000 g, more preferably 100 to 5,000 g, and particularly preferably 300 to 1,500 g with respect to 1 kg of the cellulose fiber. If the amount added is less than 1 g, the effect of adding the additive (A) may not be obtained. On the other hand, even if the amount added exceeds 10,000 g, the effect of adding the additive (A) may reach a plateau.

(Additive (B))
The additive (B) consists of at least one of urea and a urea derivative. As the additive (B), for example, urea, thiourea, biuret, phenylurea, benzylurea, dimethylurea, diethylurea, tetramethylurea and the like can be used. These ureas or urea derivatives can be used alone or in combination of two or more. However, it is preferable to use urea.

When the additive (B) is heated, it is decomposed into isocyanic acid and ammonia as shown in the following reaction formula (1). Isocyanic acid is very reactive and forms hydroxyl groups and carbamate of cellulose as shown in the following reaction formula (2).
NH _2- CO-NH ₂ → HN = C = O + NH ₃ ... (1)
Cell-OH + H-N = C = O → Cell-OC-NH ₂ ... (2)

The amount of the additive (B) added is preferably 0.01 to 100 mol, more preferably 0.2 to 20 mol, and particularly preferably 0.5 to 10 mol with respect to 1 mol of the additive (A). If the amount added is less than 0.01 mol, carbamate may not be sufficiently introduced into the cellulose fibers. On the other hand, even if the amount added exceeds 100 mol, the effect of adding urea may reach a plateau.

(heating)
The heating temperature when heating the cellulose fiber to which the additive is added is preferably 100 to 210 ° C, more preferably 100 to 200 ° C, and particularly preferably 100 to 180 ° C. When the heating temperature is 100 ° C. or higher, an ester of phosphorous acid can be introduced. However, if the heating temperature exceeds 210 ° C., the deterioration of cellulose progresses rapidly, which may cause coloring or decrease in viscosity.

The pH at the time of heating the cellulose fiber to which the additive is added is preferably 3 to 12, more preferably 4 to 11, and particularly preferably 6 to 9. The lower the pH, the easier it is for the ester and carbamate of phosphorous acid to be introduced. However, if the pH is less than 3, the deterioration of cellulose may progress rapidly.

It is preferable to heat the cellulose fiber to which the additive is added until the cellulose fiber is dried. Specifically, the cellulose fibers are dried until the moisture content is preferably 10% or less, more preferably 0.1% or less, and particularly preferably 0.001% or less. Of course, the cellulose fibers may be in an absolutely dry state without moisture.

The heating time of the cellulose fiber to which the additive is added is, for example, 1 to 1,440 minutes, preferably 10 to 180 minutes, and more preferably 30 to 120 minutes. If the heating time is too long, the introduction of phosphorous acid esters and carbamate may proceed too much. Further, if the heating time is too long, the cellulose fibers may turn yellow.

As an apparatus for heating the cellulose fiber to which the additive is added, for example, a hot air dryer, a paper machine, a dry pulp machine and the like can be used.

(Preprocessing)
Prior to introducing an ester of phosphorous acid containing a cation composed of an inorganic substance into the cellulose fiber and / or after introducing an ester of phosphorous acid containing a cation composed of an inorganic substance into the cellulose fiber, the cellulose fiber is subjected to. If necessary, pretreatment such as beating can be performed. By pretreating the pulp fiber prior to the defibration of the cellulose fiber, the number of defibration can be significantly reduced and the energy for defibration can be reduced.

The pretreatment of the cellulose fibers can be carried out by a physical method or a chemical method, preferably a physical method and a chemical method. The pretreatment by the physical method and the pretreatment by the chemical method can be performed simultaneously or separately.

As the pretreatment by the physical method, it is preferable to adopt tapping. When the cellulose fibers are beaten, the cellulose fibers are trimmed. Therefore, the entanglement of the cellulose fibers is prevented (prevention of aggregation). From this point of view, beating is preferably carried out until the freeness of the cellulose fibers is 700 ml or less, more preferably 500 ml or less, and particularly preferably 300 ml or less. The freeness of the cellulose fiber is a value measured according to JIS P8121-2 (2012). Further, the beating can be performed using, for example, a refiner, a beater, or the like.

Pretreatments by chemical methods include, for example, hydrolysis of polysaccharides with acid (acid treatment), hydrolysis of polysaccharides with enzymes (enzyme treatment), swelling of polysaccharides with alkali (alkali treatment), and oxidation of polysaccharides with oxidizing agents (alkaline treatment). Oxidation treatment), reduction of polysaccharides with a reducing agent (reduction treatment), and the like can be exemplified. However, as the pretreatment by the chemical method, it is preferable to carry out an enzyme treatment, and in addition, it is more preferable to carry out one or more treatments selected from an acid treatment, an alkali treatment and an oxidation treatment. Hereinafter, the enzyme treatment and the alkali treatment will be described in order.

As the enzyme used for the enzyme treatment, it is preferable to use at least one of a cellulase-based enzyme and a hemicellulase-based enzyme, and it is more preferable to use both in combination. The use of these enzymes facilitates the defibration of cellulose fibers. The cellulase-based enzyme induces the decomposition of cellulose in the presence of water. In addition, hemicellulose-based enzymes induce the decomposition of hemicellulose in the presence of water.

Examples of cellulase-based enzymes include the genus Trichoderma, the genus Acremonium, the genus Aspergillus, the genus Fanerochaete, the genus Trametes, and the genus Trametes. Bacteria, Humicola, filamentous fungi, Bacillus, bacteria, Schizophyllum, Streptomyces, bacteria, Pseudomonas, bacteria, etc. Enzymes can be used. These cellulase-based enzymes can be purchased as reagents or commercially available products. Examples of commercially available products include cell leucine T2 (manufactured by HPI), Meicerase (manufactured by Meiji Seika), Novozyme 188 (manufactured by Novozyme), Multifect CX10L (manufactured by Genencore), and cellulase enzyme GC220 (manufactured by Genecore). Manufactured by) and the like can be exemplified.

Further, as the cellulase-based enzyme, either EG (endoglucanase) or CBH (cellobiohydrolase) can be used. EG and CBH may be used alone or in combination. Alternatively, it may be used in combination with a hemicellulase-based enzyme.

As the hemicellulase-based enzyme, for example, xylanase, which is an enzyme that decomposes xylan, mannase, which is an enzyme that decomposes mannan, and arabanase, which is an enzyme that decomposes araban, can be used. can. In addition, pectinase, which is an enzyme that decomposes pectin, can also be used.

Hemicellulose is a polysaccharide excluding pectins located between cellulose microfibrils in the plant cell wall. Hemicellulose is diverse and varies between wood types and cell wall layers. Glucomannan is the main component in the secondary walls of softwoods, and 4-O-methylglucuronoxylan is the main component in the secondary walls of hardwoods. Therefore, when cellulose fine fibers are obtained from softwood bleached kraft pulp (NBKP), it is preferable to use mannase. Further, when cellulose fine fibers are obtained from hardwood bleached kraft pulp (LBKP), it is preferable to use xylanase.

The amount of enzyme added to the cellulose fiber is determined by, for example, the type of enzyme, the type of wood used as a raw material (conifer or hardwood), the type of mechanical pulp, and the like. However, the amount of the enzyme added to the cellulose fibers is preferably 0.1 to 3% by mass, more preferably 0.3 to 2.5% by mass, and particularly preferably 0.5 to 2% by mass. If the amount of the enzyme added is less than 0.1% by mass, the effect of adding the enzyme may not be sufficiently obtained. On the other hand, if the amount of the enzyme added exceeds 3% by mass, cellulose may be saccharified and the yield of cellulose fine fibers may decrease. In addition, there is also a problem that the improvement of the effect corresponding to the increase in the addition amount cannot be recognized.

When a cellulase-based enzyme is used as the enzyme, the pH at the time of enzyme treatment is preferably in a weakly acidic region (pH = 3.0 to 6.9) from the viewpoint of the reactivity of the enzyme reaction. On the other hand, when a hemicellulase-based enzyme is used as the enzyme, the pH at the time of enzyme treatment is preferably in a weak alkaline region (pH = 7.1 to 10.0).

The temperature during the enzyme treatment is preferably 30 to 70 ° C., more preferably 35 to 65 ° C., and particularly preferably 40 to 60 ° C., regardless of whether the cellulase-based enzyme or the hemicellulase-based enzyme is used as the enzyme. .. When the temperature at the time of enzyme treatment is 30 ° C. or higher, the enzyme activity is unlikely to decrease, and it is possible to prevent a long treatment time. On the other hand, if the temperature at the time of enzyme treatment is 70 ° C. or lower, inactivation of the enzyme can be prevented.

The enzyme treatment time is determined by, for example, the type of enzyme, the temperature of the enzyme treatment, the pH at the time of the enzyme treatment, and the like. However, the general enzyme treatment time is 0.5 to 24 hours.

After the enzyme treatment, it is preferable to inactivate the enzyme. As a method for inactivating the enzyme, for example, there are a method of adding an alkaline aqueous solution (preferably pH 10 or higher, more preferably pH 11 or higher), a method of adding hot water at 80 to 100 ° C., and the like.

Next, the above-mentioned alkaline treatment method will be described.
As a method of alkaline treatment, for example, there is a method of immersing a cellulose fiber in which an ester of phosphorous acid or the like is introduced in an alkaline solution.

The alkaline compound contained in the alkaline solution may be an inorganic alkaline compound or an organic alkaline compound. Examples of the inorganic alkali compound include hydroxides of alkali metals or alkaline earth metals, carbonates of alkali metals or alkaline earth metals, and phosphates of alkali metals or alkaline earth metals. Further, as the hydroxide of the alkali metal, for example, lithium hydroxide, sodium hydroxide, potassium hydroxide and the like can be exemplified. Examples of the hydroxide of the alkaline earth metal include calcium hydroxide and the like. Examples of the alkali metal carbonate include lithium carbonate, lithium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate, sodium carbonate, sodium hydrogen carbonate and the like. Examples of the carbonate of the alkaline earth metal include calcium carbonate and the like. Examples of the alkali metal phosphate include lithium phosphate, potassium phosphate, trisodium phosphate, and disodium hydrogen phosphate. Examples of the alkali earth metal phosphate include calcium phosphate, calcium hydrogen phosphate, and the like.

Examples of the organic alkaline compound include ammonia, aliphatic amines, aromatic amines, aliphatic ammonium, aromatic ammonium, heterocyclic compounds and their hydroxides, carbonates and phosphates. Specifically, for example, for example, ammonia, hydrazine, methylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, butylamine, diaminoethane, diaminopropane, diaminobutane, diaminopentane, diaminohexane, cyclohexylamine, aniline. , Tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, pyridine, N, N-dimethyl-4-aminopyridine, ammonium carbonate, ammonium hydrogencarbonate, Examples thereof include diammonium hydrogen phosphate.

The solvent of the alkaline solution may be either water or an organic solvent, but it is preferably a polar solvent (a polar organic solvent such as water or alcohol), and more preferably an aqueous solvent containing at least water.

The pH of the alkaline solution at 25 ° C. is preferably 9 or higher, more preferably 10 or higher, and particularly preferably 11-14. When the pH is 9 or more, the yield of cellulose fine fibers is high. However, if the pH exceeds 14, the handleability of the alkaline solution deteriorates.

(Washing)
Cellulose fibers into which an ester of phosphorous acid or the like has been introduced are preferably washed prior to defibration. By cleaning the cellulose fibers, by-products and unreacted products can be washed away. Further, if this cleaning precedes the alkaline treatment in the pretreatment, the amount of the alkaline solution used in the alkaline treatment can be reduced.

The cellulose fibers can be washed with, for example, water, an organic solvent, or the like.

(Defibration)
Cellulose fibers into which an ester of phosphorous acid or the like has been introduced are defibrated (miniaturized) after washing. By this defibration, the pulp fibers are microfibrillated into cellulose fine fibers.

When defibrating the cellulose fibers, it is preferable to make the cellulose fibers into a slurry. The solid content concentration of this slurry is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, and particularly preferably 1.0 to 5.0% by mass. If the solid content concentration is within the above range, defibration can be performed efficiently.

For defibration of cellulose fibers, for example, high-pressure homogenizers, homogenizers such as high-pressure homogenizers, high-speed rotary homogenizers, grinders, stone mill friction machines such as grinders, conical refiners, refiners such as disc refiners, uniaxial kneaders, and many It can be carried out by selectively using one or more means from a shaft kneader, various bacteria and the like. However, it is preferable to defibrate the cellulose fibers by using a device / method for refining the cellulose fibers with a water stream, particularly a high-pressure water stream. According to this device / method, the dimensional uniformity and dispersion uniformity of the obtained cellulose fine fibers are very high. On the other hand, for example, when a grinder that grinds between rotating grindstones is used, it is difficult to uniformly refine the cellulose fibers, and in some cases, there is a possibility that undissolved fiber lumps may remain.

As a grinder used for defibrating cellulose fibers, for example, there is a mass colloider of Masuko Sangyo Co., Ltd. Further, as a device for miniaturizing with a high-pressure water flow, for example, Starburst (registered trademark) of Sugino Machine Limited, Nanovater (registered trademark) of Yoshida Kikai Kogyo Co., Ltd., and the like exist. Further, as a high-speed rotary homogenizer used for defibrating cellulose fibers, there is Clairemix-11S manufactured by M-Technique.

In addition, the present inventors have defibrated cellulose fibers by a method of grinding between rotating grindstones and a method of refining with a high-pressure water stream, respectively, and when each of the obtained fibers is observed under a microscope, high pressure is obtained. It has been found that the fibers obtained by the method of refining with a water stream have a more uniform fiber width.

For defibration by high-pressure water flow, the dispersion liquid of cellulose fibers is pressurized to, for example, 30 MPa or more, preferably 100 MPa or more, more preferably 150 MPa or more, particularly preferably 220 MPa or more (high pressure conditions), and the pore diameter is 50 μm or more. It is preferable to use a method of ejecting the fiber from the nozzle of No. 1 and reducing the pressure so that the pressure difference is, for example, 30 MPa or more, preferably 80 MPa or more, more preferably 90 MPa or more (decompression condition). Pulp fibers are defibrated by the cleavage phenomenon caused by this pressure difference. When the pressure under the high pressure condition is low or when the pressure difference from the high pressure condition to the depressurized condition is small, the defibration efficiency decreases, and it becomes necessary to repeatedly defibrate (spout from the nozzle) in order to obtain the desired fiber width. ..

As a device for defibrating by a high-pressure water stream, it is preferable to use a high-pressure homogenizer. The high-pressure homogenizer refers to a homogenizer having an ability to eject a slurry of cellulose fibers at a pressure of, for example, 10 MPa or more, preferably 100 MPa or more. When the cellulose fibers are treated with a high-pressure homogenizer, collisions between the cellulose fibers, pressure difference, microcavitation, etc. act to effectively defibrate the cellulose fibers. Therefore, the number of defibration treatments can be reduced, and the production efficiency of cellulose fine fibers can be improved.

As the high-pressure homogenizer, it is preferable to use one in which a slurry of cellulose fibers collides with each other in a straight line. Specifically, for example, a counter-collision type high-pressure homogenizer (microfluidizer / MICROFLUIDIZER®, wet jet mill). In this device, two upstream flow paths are formed so that the pressurized cellulose fiber slurries collide with each other at the confluence. Further, the cellulose fiber slurries collide at the confluence, and the collided cellulose fiber slurries flow out from the downstream flow path. The downstream flow path is provided perpendicular to the upstream side flow path, and a T-shaped flow path is formed by the upstream side flow path and the downstream side flow path. When such a counter-collision type high-pressure homogenizer is used, the energy given by the high-pressure homogenizer is converted to the collision energy to the maximum, so that the cellulose fibers can be defibrated more efficiently.

In the defibration of cellulose fibers, the average fiber width, average fiber length, water retention, crystallinity, peak value of pseudo-particle size distribution, and pulp viscosity of the obtained cellulose fine fibers are set to the desired values or evaluations described above. It is preferable to do so.

(concentrated)
A dispersion containing cellulose fine fibers into which an ester of phosphorous acid containing a cation composed of an inorganic substance has been introduced is concentrated to obtain a cellulose fine fiber-containing substance. In this embodiment, an alkali metal ion-containing material is added to obtain cellulose fine fibers, and the obtained cellulose fine fiber-containing material contains cations composed of inorganic substances, so that this concentration is extremely easy. Become.

The concentration of the cellulose fine fibers is preferably carried out so that the water content is less than 90% by mass, and particularly preferably less than 80% by mass. Concentration with a water content of more than 90% by mass may be considered insufficient to solve the problem of transportation energy.

Examples of the concentration method (dehydration method, drying method, etc.) include rotary kiln drying, disk drying, air flow drying, medium flow drying, spray drying, drum drying, screw conveyor drying, paddle drying, uniaxial kneading drying, and multi-axis drying. One type or a combination of two or more types can be adopted from kneading drying, vacuum drying, stirring drying and the like. However, it is preferable to adopt drum drying.

(Agglutination)
The step of obtaining the cellulose fine fiber-containing material from the dispersion liquid containing the cellulose fine fiber into which the ester of phosphorous acid containing a cation consisting of an inorganic substance is introduced may include a step of aggregating the cellulose fine fiber. As the flocculant that agglomerates (aggregates cellulose fine fibers), for example, one or more of alcohols, metal salts, acids, cationic surfactants, cationic polymer flocculants and the like are used. Can be used in combination.

As the alcohols as the flocculant, for example, lower alcohols, polyhydric alcohols, aliphatic alcohols and the like can be used. Specifically, for example, one or a combination of two or more of methanol, ethanol, isopropanol, butanol, ethylene glycol, glycerin, octanol, dodecanol, tetradecanol, cetanol, octadecyl alcohol, oleyl alcohol and the like is used. be able to.

The amount of alcohols added as a flocculant is preferably 1 to 100,000 g, more preferably 10 to 10,000 g, based on 1 kg of cellulose fine fibers.

Examples of metal salts as coagulants include aluminum sulfate, magnesium sulfate, calcium sulfate, calcium sulfate, sodium sulfate, ferric sulfate, sodium chloride, aluminum chloride, magnesium chloride, calcium chloride, polyaluminum chloride, and phosphoric acid. One or a combination of two or more of lithium, sodium phosphate, potassium phosphate, sodium phosphite, lithium sulphate, potassium sulphate and the like can be used.

The amount of the metal salt added as the flocculant is preferably 1 to 100,000 g, more preferably 10 to 10,000 g with respect to 1 kg of the cellulose fine fibers.

The acid as the flocculant may be either an inorganic acid or an organic acid. As the inorganic acid, for example, one or a combination of two or more of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, phosphorous acid and the like can be used. Examples of organic acids include glycolic acid, lactic acid, tartronic acid, glyceric acid, hydroxybutyric acid, malic acid, tartaric acid, citric acid, isocitrate, mevalonic acid, pantoic acid, ricinolic acid, stearic acid, maleic acid, formic acid and acetic acid. It is possible to use one kind or a combination of two or more kinds from among the above.

The pH when an acid is added to the cellulose fine fibers is preferably 4.0 or less. However, when the pH is 1.0 or less, there is a concern that the physical properties of the cellulose fine fibers may deteriorate due to hydrolysis.

Examples of the cationic surfactant as a flocculant include quaternary ammonium salt type (stearyltrimethylammonium chloride, behenyltrimethylammonium chloride, distearyldimethylammonium chloride, lanolin sulfate fatty acid aminopropylethyldimethylammonium, etc.) and amines. One or a combination of two or more of the salt types (diethylaminoethylamide stearate, dilaurylamine hydrochloride, oleylamine hydrochloride, etc.) and the like can be used.

The amount of the cationic surfactant added is preferably 1 to 100,000 g, more preferably 10 to 10,000 g per 1 kg of cellulose fine fibers.

Cationic polymer as a flocculant Examples of the flocculant include homopolymers of cationic monomers, copolymers of cationic monomers and nonionic monomers, condensing polyamines, polyvinylamines, polyvinylamidines, and poly (meth) allylamines. , Diciandiamide / formalin condensate, polyethyleneimine, polyvinylimidarin, polyvinylpyridine, diallylamine salt / sulfur dioxide copolymer, polydimethyldialylammonium salt / sulfur dioxide copolymer, polydimethyldialylammonium salt, polydimethyldialylammonium salt / One or a combination of two or more of the acrylamide copolymer, allylamine salt polymer and the like can be used.

The amount of the cationic polymer flocculant added is preferably 1 to 100,000 g, more preferably 10 to 10,000 g per 1 kg of cellulose fine fibers.

(Redispersant)
The cellulose fine fiber-containing material may contain a redispersant that enhances redispersion in water. It is considered that when the redispersant is contained, the hydrogen bond between the cellulose fine fibers is weakened, and the dispersion between the cellulose fine fibers is promoted by the electrostatic repulsion action and the osmotic pressure effect in water.

The redispersant is preferably a hydroxy acid, a hydroxy salt, a glycerin or a glycerin derivative.

(Redispersion method)
In redispersing the cellulose fine fiber-containing material in water, for example, one or more of magnetic stirrers, agitators, propeller mixers, homomixers, homogenizers, pipeline mixers, turbine mixers, paddle mixers, etc. are used. Can be used in combination.

(Cellulose fine fiber dispersion)
The cellulose fine fiber-containing material can be obtained as a cellulose fine fiber dispersion liquid by simply mixing with water.

Next, examples of the present invention will be described.
A test was conducted to confirm the redispersibility of the cellulose fine fiber-containing material according to this embodiment. The cellulose fine fiber-containing material was redispersed in water so as to have a concentration of 1.0% by mass. The details are as follows.

[Test Example 1]
Reagent A was prepared by mixing 13 g of sodium hydrogen phosphite pentahydrate, 10.8 g of urea, and 76.2 g of water. 100 g of the prepared reagent A and 10 g of the raw material pulp (NBKP: moisture 98.0% by mass) dry weight were mixed and dried at 105 ° C. The dried pulp was reacted at 130 ° C. for 2 hours, and washing with water and filtration were repeated twice to obtain cellulose fibers (phosphorous acid-modified pulp) into which an ester of phosphorous acid containing a cation consisting of an inorganic substance was introduced. The obtained phosphorous acid-modified pulp was diluted with distilled water so as to have a solid content of 10% by mass to obtain a phosphorous acid-modified pulp slurry (dispersion liquid). The phosphorous acid-modified pulp slurry was pre-beaten at 9200 rpm using a PFI mill. The pre-beaten phosphorous acid-modified pulp slurry was adjusted to a solid content concentration of 1% and subjected to defibration treatment twice using a high-pressure homogenizer to obtain an aqueous dispersion of cellulose fine fibers having a concentration of 1.0% by mass. .. This water dispersion of cellulose fine fibers having a concentration of 1.0% by mass was dried at 105 ° C. for 6 hours to obtain a film-like cellulose fine fiber-containing product (dried product). The water content of the cellulose fine fiber-containing material was 9.8% by mass.

Water is added to the cellulose fine fiber-containing material obtained as described above so that the solid content concentration becomes 1.0% by mass, and the mixture is stirred at 800 rpm for 60 minutes using a magnetic stirrer to contain the cellulose fine fibers. A redispersion of the material was obtained. The obtained redispersion liquid was allowed to stand for 10 minutes, and then the concentration of the supernatant liquid was measured. The supernatant concentration (%), sodium amount (mmol), and degree of substitution (DS) are shown in Table 1.

[Test Examples 2-5]
Test Example 2 is the same as Test Example 1 except that 0.22 g of sodium hydroxide is added to the phosphorous acid-modified pulp slurry before defibration, which was pre-beaten before making it into a cellulose fine fiber-containing material (dried product). bottom.

Test Example 3 was the same as Test Example 1 except that the dried pulp was reacted at 140 ° C. for 2 hours.

Test Example 4 was the same as Test Example 1 except that the dried pulp was reacted at 170 ° C. for 2 hours.

Test Example 5 was the same as Test Example 1 except that the dried pulp was reacted at 180 ° C. for 2 hours.

In Test Examples 3 to 5, the amount of sodium is changed by changing the reaction temperature of the dried pulp as described above.

(Discussion)
From the test results, it was found that the redispersibility increases as the amount of sodium increases. The degree of substitution (DS) of the phosphite group in Test Example 1 and Test Example 2 is 0.14, which is the same.

The present invention can be used as a cellulose fine fiber-containing material and its production how.

Claims (4)

Contains cellulose fibrils and flocculants into which phosphorous acid esters containing cations consisting of inorganic substances have been introduced.
The ratio of cations composed of the inorganic substance to 1 g of the cellulose fine fibers is 0.14 mmol or more.
Cellulose fine fiber-containing material. The coagulant contains at least one of alcohols, metal salts, cationic surfactants, and cationic polymer flocculants.
The amount of the flocculant added is 1 to 100,000 g with respect to 1 kg of the cellulose fine fibers.
The cellulose fine fiber-containing product according to claim 1. After introducing an ester of phosphorous acid into the cellulose fiber, the fiber is defibrated to obtain a dispersion liquid containing the cellulose fine fiber, and in this process, an alkali metal ion-containing substance is added to the cellulose fiber.
And to obtain a cellulose fine fiber-containing product by concentrating the dispersion,
The step of obtaining the cellulose fine fiber-containing material from the dispersion liquid includes a step of agglutinating the cellulose fine fibers.
A method for producing a cellulose fine fiber-containing material. An acid is used as the aggregating agent for aggregating, and the pH when the acid is added is set to 4.0 or less.
The method for producing a cellulose fine fiber-containing material according to claim 3.