JP2018184596A - Chemically modified cellulose powder and method for producing the same - Google Patents

Abstract

A chemically modified cellulose powder and a method for producing the same are provided.
[MEANS FOR SOLVING PROBLEMS] A cellulose powder containing an introduced hydrophilic functional group, wherein the amount of the introduced hydrophilic functional group is 0.1 mmol / g or more and 3.0 mmol / g or less, and a 50% particle size ( D50) is a cellulose powder characterized by being 1 μm or more and 100 μm or less.
[Selection figure] None

Description

  The present invention relates to a chemically modified cellulose powder and a method for producing the same.

  Conventionally, cellulose powder has been used for food additives, tablet excipients, dispersants, shape-retaining agents, water-retaining agents, filter aids, fillers, paints and adhesives because of its water retention, oil absorption, and shape retention properties. It is used in a wide range of fields such as foods, cosmetics, pharmaceuticals, building materials, ceramics, rubber, plastics, etc. as additives for pharmaceuticals, raw materials for cellulose derivatives, and industrial raw materials such as biomass materials.

  Chemical and mechanical treatments are known as methods for producing cellulose powder. When cellulose contacts with acid by chemical treatment, hydrolysis occurs, cellulose depolymerization occurs, and the degree of polymerization and yield of cellulose powder is reduced. It has been proposed to pulverize natural cellulose by using a mechanical treatment using a cellulose to obtain a cellulose powder having an average particle size of 35 μm or less and a polymerization degree of 500 or more.

  Moreover, it has been conventionally performed to chemically modify cellulose materials for the purpose of imparting or improving functionality. For example, a phosphorylated cellulose material phosphorylated for the purpose of imparting water resistance and flame retardancy is known, and Patent Document 2 discloses a modified phosphorylated cellulose fiber for papermaking having a reaction product of an amino compound and phosphoric acids. Has proposed.

JP 2014-88538 A Japanese Examined Patent Publication No. 56-85498 JP 2014-114332 A

Segal et al., Textile Research Journal, 29, 786, 1959

  There is a demand for a cellulose powder having high adsorption performance and excellent dispersibility in a liquid from the viewpoints of usage and handling properties. However, when a chemical modification treatment is performed on the cellulose powder proposed in Patent Document 1 in order to improve the adsorption performance, the degree of polymerization of cellulose may be greatly reduced depending on the treatment conditions. In order to obtain excellent dispersibility in a liquid, when the fibers are cut into powder by mechanically treating the chemically modified fibers proposed in Patent Document 2, cellulose I type The crystal structure tends to collapse.

  Patent Document 3 proposes a method for producing a cellulose material, in which an anionic cellulose derivative is added to a carboxy group-containing cellulose fiber obtained by oxidizing natural cellulose fibers, followed by a refining process for performing a refining treatment. However, Patent Document 3 is intended for cellulose nanofibers and not for cellulose powder.

  An object of the present invention is to provide a cellulose powder having high adsorption performance and excellent dispersibility in a liquid.

  The present invention for solving the above problems is a cellulose powder containing an introduced hydrophilic functional group, wherein the amount of the introduced hydrophilic functional group is from 0.1 mmol / g to 3.0 mmol / g. There is a cellulose powder having a 50% particle size of 1 μm or more and 100 μm or less.

  According to the present invention, it is possible to provide a cellulose powder having high adsorption performance and excellent dispersibility in a liquid.

It is a figure which shows the relationship between the amount of NaOH dripping with respect to a titration object, and electrical conductivity.

  Hereinafter, embodiments of the present invention will be specifically described. The following embodiments are for illustrative purposes, and the present invention should not be construed as being limited to these embodiments.

(Cellulose powder)
The cellulose powder according to the embodiment of the present invention is a cellulosic material having a powder form, and is also referred to as powdered cellulose or powdered cellulose. Powder refers to a solid material that has been crushed very finely.

(Cellulose raw material)
Although it does not specifically limit as a cellulose raw material for obtaining the cellulose powder by embodiment of this invention, It is preferable to use a pulp from the point of being easy to acquire and cheap.

  The pulp is mainly composed of cellulose, hemicellulose, lignin and may contain lignocellulose. Lignocellulose is a complex hydrocarbon polymer that constitutes the cell walls of plants, and is known to be composed mainly of polysaccharide cellulose, hemicellulose, and lignin, which is an aromatic polymer. In the embodiment of the present invention, the chemical structure of lignocellulose is not limited, and the lignin content in lignocellulose is not limited. Since lignocellulose contains lignin unlike a highly purified cellulose raw material, it has a characteristic that it has a high affinity with a resin and is easily imparted with a functional group. In addition, since no delignification and bleaching steps are required, lignocellulose can be obtained at a relatively low cost. In the embodiments of the present invention, each or a combination of cellulose, hemicellulose, and lignocellulose can be collectively treated as cellulose unless otherwise specified.

  Pulp can be obtained by treating a plant material by mechanical pulping, chemical pulping, or a combination of mechanical pulping and chemical pulping. The mechanical pulping method is a method of pulping by mechanical force such as a grinder or refiner while leaving lignin. The chemical pulping method is a method of pulping by adjusting the content of lignin using a chemical. When the degree of chemical treatment for the plant material is increased, the contents of hemicellulose and lignin are reduced, and the fiber is mainly composed of cellulose.

  There is no restriction | limiting in particular in the kind of pulp, For example, pulps, such as a wood origin pulp and a non-wood origin pulp, can be used. Wood-derived pulp is pulp obtained by digesting hardwood or softwood by a known method. Pulp includes chemical pulp such as kraft pulp (KP), sulfite pulp (SP) and soda pulp (AP); semi-chemical pulp such as semi-chemical pulp (SCP) and chemi-grandwood pulp (CGP); groundwood pulp (GP) ), Thermomechanical pulp (TMP, BCTMP), refiner groundwood pulp (RGP), or other mechanical pulp. Non-wood-derived pulp is a pulp obtained by digesting non-wood materials such as kenaf, rice straw, straw, bamboo, bagasse (sugar cane bagasse), flax, straw, cocoon, straw, cannabis, and hemp by known methods. is there. The pulp may be bleached pulp or unbleached pulp. The pulp may be dissolving pulp (DP). One kind of pulp may be used alone, or two or more kinds of pulp may be mixed and used.

  Although there is no restriction | limiting in particular in the shape of the pulp used as the starting raw material for obtaining a cellulose powder in embodiment of this invention, Considering industrial production, the sheet-like pulp comprised by pulp fiber (henceforth a pulp sheet) ) Is preferable. The pulp sheet may be wound in a roll shape or may be folded.

(Hydrophilic functional group)
A hydrophilic functional group is introduced into the cellulose powder according to the embodiment of the present invention. Examples of hydrophilic functional groups applicable to the embodiments of the present invention include a phosphate group, a carboxyl group, a hydroxy group, and a sulfone group. Cellulose powder contains one or more functional groups selected from the group consisting of these hydrophilic functional groups.

(Production method)
The cellulose powder according to the embodiment of the present invention can be produced by a method including a step of introducing a hydrophilic functional group into a cellulose raw material and a step of pulverizing the cellulose raw material into which the hydrophilic functional group has been introduced. it can. According to this method, since chemical modification is performed in the pre-treatment, it is possible to increase the amount of functional groups introduced while suppressing damage to cellulose by chemicals.

<Introduction of hydrophilic functional groups>
The method for introducing the hydrophilic functional group into the cellulose raw material is not particularly limited, and examples thereof include oxidation treatment or treatment with a compound capable of forming a covalent bond with the functional group in cellulose.

  The oxidation treatment is a treatment for converting a hydroxy group in cellulose into an aldehyde group or a carboxy group. Examples of the oxidation treatment include TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidation treatment and treatment using various oxidizing agents (sodium chlorite, ozone, etc.). An example of the oxidation treatment is a method described in Biomacromolecules 8, 2485-2491, 2007 (Saito et al.), But is not particularly limited.

  The treatment with the compound can be carried out by mixing the cellulose raw material in a dry or wet state with a compound that reacts with the cellulose raw material, thereby introducing the functional group into the cellulose raw material. In order to promote the reaction at the time of introduction, a heating method is particularly effective. The heat treatment temperature for introducing the functional group is not particularly limited, but it is preferably a temperature range in which thermal decomposition or hydrolysis of the cellulose raw material hardly occurs. For example, it is preferable that it is 250 degrees C or less from a viewpoint of the thermal decomposition temperature of a cellulose, and it is preferable to heat-process at 100-170 degreeC from a viewpoint of suppressing hydrolysis of a cellulose.

  The compound that reacts with the cellulose raw material is not particularly limited as long as cellulose powder can be obtained and a hydrophilic functional group is introduced.

  In the case of introducing a hydrophilic functional group, examples of the compound that reacts with the cellulose raw material include a compound having a group derived from phosphoric acid, a compound having a group derived from carboxylic acid, a compound having a hydroxy group, and a group derived from sulfonic acid. And the like. From the viewpoint of ease of handling and reactivity with cellulose, a compound having at least one selected from the group consisting of a group derived from phosphoric acid and a group derived from carboxylic acid is preferred. Although it is more preferable that these compounds form an ester or / and ether with cellulose, it is not particularly limited.

(Functional group introduction amount)
In this specification, “functional group introduction amount” or “substituent introduction amount”, or simply “introduction amount” and “substituent amount” are functional groups for cellulose raw materials (cellulose fibers) for producing cellulose powder. (Unit: mmol / g). It shows that many functional groups are introduce | transduced, so that this value is large. When the functional group (substituent) is a phosphate group, it is also referred to as “phosphate group introduction amount” or “phosphate group amount”.

The amount of hydrophilic functional group introduced can be measured, for example, by the titration method as follows.
A cellulose fiber-containing slurry containing about 0.04 g of solid content in an absolutely dry mass is collected and diluted to about 50 g using ion-exchanged water. While stirring this solution, a change in the value of electrical conductivity when a 0.01 N sodium hydroxide aqueous solution was added dropwise (hereinafter referred to as “N”) was measured. The amount of 0.01N sodium hydroxide aqueous solution added at this time is defined as the amount of addition at the titration end point. The amount X of substituents on the cellulose surface is represented by X (mmol / g) = 0.01 (mol / l) × V (ml) / W (g). Here, V: A dripping amount (ml) of 0.01N sodium hydroxide aqueous solution, W: solid content (g) contained in the cellulose fiber-containing slurry.

  In conductivity titration, when alkali is added, the curve shown in FIG. 1 is given. Initially, the electrical conductivity rapidly decreases (hereinafter referred to as “first region”). Thereafter, the conductivity starts to increase slightly (hereinafter referred to as “second region”). Thereafter, the conductivity increment increases (hereinafter referred to as “third region”). The boundary point between the second region and the third region is defined as a point at which the amount of change in conductivity twice, that is, the increase (inclination) in conductivity is maximized. That is, three areas appear. Among these, the amount of alkali required in the first region is equal to the amount of strongly acidic groups in the slurry used for titration, and the amount of alkali required in the second region is the amount of weakly acidic groups in the slurry used for titration. Will be equal. When the phosphoric acid group undergoes condensation, apparently weakly acidic groups are lost, and the amount of alkali required in the second region is reduced compared to the amount of alkali required in the first region. On the other hand, the amount of strongly acidic groups coincides with the amount of phosphorus atoms regardless of the presence or absence of condensation, so that the amount of phosphate groups introduced (or the amount of phosphate groups) or the amount of substituent introduced (or the amount of substituents) is simply When said, it represents the amount of strongly acidic group.

  When the hydrophilic functional group to be introduced is at least one selected from the group consisting of a group derived from phosphoric acid, a group derived from carboxylic acid, a hydroxy group, and a group derived from sulfonic acid, The introduction amount of the group is preferably 0.1 mmol / g or more, and preferably 3.0 mmol / g or less. When the introduction amount is less than 0.1 mmol / g, the effect of exerting the function based on the hydrophilic functional group is small. If the amount introduced exceeds 3.0 mmol / g, the type I crystal structure of cellulose tends to collapse due to the acid at the time of introduction or pulverization treatment.

  When a compound having a phosphoric acid-derived group is used as the compound that reacts with the cellulose raw material, it is not particularly limited, but is composed of phosphoric acid, polyphosphoric acid, phosphorous acid, phosphonic acid, polyphosphonic acid, or a salt or ester thereof. It is at least one selected from the group. Among these, a compound having a phosphoric acid group is preferable because it is low-cost, easy to handle, and can further improve refinement (defibration) efficiency by introducing a phosphoric acid group into a cellulose raw material, but is not particularly limited. .

  Although it does not specifically limit as a compound which has a phosphoric acid group, Lithium dihydrogen phosphate which is phosphoric acid and the lithium salt of phosphoric acid, Dilithium hydrogen phosphate, Trilithium phosphate, Lithium pyrophosphate, Lithium polyphosphate is mentioned. . Furthermore, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium pyrophosphate and sodium polyphosphate which are sodium salts of phosphoric acid are mentioned. Furthermore, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, potassium pyrophosphate, and potassium polyphosphate which are potassium salts of phosphoric acid are mentioned. Further examples include ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium pyrophosphate, and ammonium polyphosphate, which are ammonium salts of phosphoric acid.

  Of these, phosphoric acid, sodium phosphate, phosphoric acid potassium salt, and phosphoric acid ammonium salt are preferred from the viewpoint of high efficiency in introducing a phosphate group and easy industrial application. Sodium dihydrogen phosphate Although disodium hydrogen phosphate is more preferable, it is not particularly limited.

  In addition, the compound is preferably used as an aqueous solution because of the uniformity of the reaction and the introduction efficiency of the group derived from phosphoric acid, but it is not particularly limited. The pH of the aqueous solution of the compound is not particularly limited, but is preferably 7 or less because the efficiency of introducing a phosphate group is high. Although pH 3-7 is especially preferable from a viewpoint of suppressing hydrolysis of cellulose, it is not particularly limited.

  When a compound having a carboxylic acid-derived group is used as the compound that reacts with the cellulose raw material, it is not particularly limited, but from the group consisting of a compound having a carboxy group, an acid anhydride of a compound having a carboxy group, and derivatives thereof. At least one selected.

  The compound having a carboxy group is not particularly limited, and examples thereof include dicarboxylic acid compounds such as maleic acid, succinic acid, phthalic acid, fumaric acid, glutaric acid, adipic acid and itaconic acid, and tricarboxylic acid compounds such as citric acid and aconitic acid. .

  The acid anhydride of the compound having a carboxy group is not particularly limited, and examples thereof include acid anhydrides of dicarboxylic acid compounds such as maleic anhydride, succinic anhydride, phthalic anhydride, glutaric anhydride, adipic anhydride, and itaconic anhydride. It is done.

  Although it does not specifically limit as a derivative | guide_body of the compound which has a carboxy group, The derivative of the acid anhydride of the compound which has a carboxy group and the acid anhydride imidation of a compound which has a carboxy group are mentioned. The acid anhydride imidized compound having a carboxy group is not particularly limited, and examples thereof include imidized dicarboxylic acid compounds such as maleimide, succinimide, and phthalimide.

  The acid anhydride derivative of the compound having a carboxy group is not particularly limited. For example, at least some of the hydrogen atoms of the acid anhydride of the compound having a carboxy group such as dimethylmaleic anhydride, diethylmaleic anhydride, diphenylmaleic anhydride are substituted (eg, alkyl group, phenyl group, etc.) ) Are substituted.

  The compound having a carboxy group may be an organic halide compound having a carboxy group. The organic halide compound having a carboxy group is not particularly limited, and examples thereof include chloroacetic acid, chloropropionic acid, chlorobutyric acid, bromoacetic acid, bromopropionic acid, bromobutyric acid, iodoacetic acid, iodopropionic acid, and iodobutyric acid.

  Among the compounds having a group derived from a carboxylic acid, maleic anhydride, succinic anhydride, and phthalic anhydride are preferred because they are easily applied industrially and easily gasified, but are not particularly limited.

  By introducing a hydrophilic functional group into the cellulose raw material, the dispersibility of cellulose in the solution can be improved.

<Washing and alkali treatment>
It is preferable to wash the cellulose into which the hydrophilic functional group has been introduced, and to wash away excessive chemicals sufficiently. Washing can be performed, for example, by repeating a process of obtaining dehydrated sheets by repeating injection of ion exchange water, uniform dispersion, and filtration and dehydration. The filter medium to be used is not particularly limited, but stainless steel, filter paper, polypropylene, nylon, polyethylene, polyester, and the like can be used. Polypropylene is preferred for acid resistance.

  Then, the dehydration sheet from which the excess chemical solution has been sufficiently washed out may be subjected to an alkali treatment to suppress degradation due to decomposition of cellulose. The alkali treatment can be performed, for example, by adding an alkaline aqueous solution to a slurry in which cellulose is dispersed in water to raise the pH. Thereafter, a washing treatment is performed again to obtain cellulose in which a functional group is introduced and excess alkaline chemicals are sufficiently washed away.

<Crushing process>
The obtained cellulose is dried and pulverized with a pulverizer, whereby the cellulose powder according to the embodiment of the present invention can be obtained. Although there is no limitation in particular in a drying process, It is preferable that it is an oven drying process, for example, it is preferable to dry for 1 to 60 minutes in the oven set to 30-70 degreeC.

  Examples of pulverizers include cutting pulverizers that cut with cutters such as cutter mills and wheelie mills, impact pulverizers that apply a cutting force by impact such as hammer mills, pin mills, and ball mills, and jet mills. An airflow type pulverizer using such an airflow can be used. In order to obtain the desired quality of powder, one-pass processing may be performed using one type of pulverizer, multi-pass processing may be performed, and multistage processing may be performed using multiple types of pulverizers. Also good. For example, a method of first roughly cutting cellulose with a cutting type pulverizer, then finely pulverizing with an impact type pulverizer, and then a method of finely pulverizing the particle size with an airflow type pulverizer is preferable. Used.

(50% particle size)
The cellulose powder according to the embodiment of the present invention is preferably set to have a 50% particle diameter of 1 μm or more and 100 μm or less from the viewpoints of usage and handling properties. The 50% particle size is preferably 5 μm to 95 μm, more preferably 5 μm to 90 μm, and particularly preferably 10 μm to 85 μm. When the 50% particle size is less than 1 μm, dust due to fine powder is likely to fly and handling properties are deteriorated. On the other hand, if the 50% particle diameter exceeds 100 μm, the use application may be limited or may not be used because it is too large.

  In the present specification, “50% particle diameter” is also called D50 or median diameter, and in the cumulative particle diameter distribution measured on a volume basis, the particle diameter on the side where the particle diameter when divided based on the particle diameter is larger. The particle diameter is such that the particles and the smaller particles are equivalent.

  The 50% particle size of the cellulose powder can be measured using, for example, a laser analysis / scattering particle size distribution measuring apparatus.

(Crystal form)
The cellulose powder according to the embodiment of the present invention preferably has a cellulose type I crystal structure.

  In general, cellulose has a plurality of crystal structures. Most natural cellulose has a cellulose type I crystal structure. The cellulose type I crystal structure is a structure called a parallel chain structure in which all reducing ends are directed in the same direction. On the other hand, for example, cellulose fibers of cellulose II, III, and IV structures are derived from cellulose having a cellulose I type crystal structure. Among these crystal structures, the cellulose I-type crystal structure is known to have a higher crystal elastic modulus than other structures. When the proportion of the cellulose I-type crystal structure in the cellulose powder is high, performance based on the high crystal elastic modulus can be expected.

  The fact that the cellulose powder has a type I crystal structure can be identified in a diffraction profile obtained from a wide-angle X-ray diffraction photograph using CuKα (λ = 1.5418Å) monochromatized with graphite. Specifically, it can be identified by having typical peaks at two positions of 2θ = 14 ° to 17 ° and 2θ = 22 ° to 23 °.

(Crystallinity)
The crystallinity of the cellulose I-type crystal structure in the cellulose powder according to the embodiment of the present invention is preferably 50% or more, more preferably 60% or more, and further preferably 70% or more. When the crystallinity of the cellulose I-type crystal structure in the cellulose powder is high, excellent performance can be expected in terms of heat resistance and low linear thermal expansion.

  The degree of crystallinity can be determined by measuring the X-ray diffraction profile and using the pattern by a conventional method (see Non-Patent Document 1).

  In general, cellulose can have an amorphous structure portion (amorphous portion) in addition to a crystal structure portion. The ratio of the crystal structure portion contained in the cellulose powder according to the embodiment of the present invention is 50% or more, preferably 60% or more, more preferably 70%, as the degree of crystallinity obtained by the X-ray diffraction method. That's it. When the ratio of the crystal structure portion in the cellulose powder is high, excellent performance can be expected in terms of heat resistance and low linear thermal expansion.

(Cation requirement)
In the embodiment of the present invention, the “cation required amount” is an index representing the anionicity of a dispersion (hereinafter, also simply referred to as slurry) in which cellulose powder is dispersed in water. The larger the absolute value of the required amount of cation, the higher the anionic property, and when it is almost zero, it indicates that it is nonionic. It can be said that the larger the absolute value of the cation demand, the higher the adsorption performance by ionic bonding. The required cation amount can be determined by a general titration method. Moreover, the example of the specific measurement method of a cation request | requirement amount was shown in the Example described below.

  The cation requirement of the cellulose powder according to the embodiment of the present invention is preferably 0.1 meq / g or more, and preferably 5 meq / g or less. When the cation requirement is less than 0.1 meq / g, the adsorption performance of the cellulose powder may be less than the required quality. When the required amount of the cation exceeds 5 meq / g, the damage received by the cellulose due to the chemical treatment for introducing the functional group is large, and the degree of polymerization and the degree of crystallization of the cellulose powder may not satisfy the required quality.

(Viscosity average degree of polymerization)
The degree of polymerization of the cellulose powder according to the embodiment of the present invention is a degree of polymerization obtained based on the viscosity, and is also referred to as a viscosity average degree of polymerization. The viscosity can be measured according to the paper pulp test method Japan Tappi T230 by the Paper Pulp Technology Association. In the examples described below, specific measurement methods and calculation formulas for the viscosity average degree of polymerization are shown.

  The viscosity average polymerization degree of the cellulose powder according to the embodiment of the present invention is preferably 500 or more. If the viscosity average polymerization degree is less than 500, it may be difficult to obtain desired physical properties according to the application. Moreover, even if the viscosity average polymerization degree is too large, it may be difficult to obtain desired physical properties, or additional processing may be required to obtain desired physical properties.

  The difference in the viscosity average polymerization degree between the cellulose material, that is, the cellulose fiber and the cellulose powder, before and after the pulverization step for obtaining the cellulose powder can be an index for estimating the damage to the cellulose by the pulverization step.

(Settling speed)
The sedimentation speed, which is the speed at which the cellulose powder sinks when the cellulose powder is dispersed and stirred in water to form a slurry and then allowed to stand, is an indicator of dispersion stability. It can be said that the faster the sedimentation rate, the lower the dispersion stability, and the slower the sedimentation rate, the better the dispersion stability. The sedimentation rate can be measured by visual comparison by the method described in the examples described below, and can be relatively compared.

  Hereinafter, although an embodiment and a comparative example explain an embodiment of the present invention in detail, the present invention is not limited by these.

(Measurement)
Regarding the examples and comparative examples, the physical properties of the cellulose material before and after the pulverization step were measured. Specifically, the functional group (phosphate group) introduction amount and the viscosity average polymerization degree were measured for the cellulose fibers to be subjected to the pulverization step. Moreover, regarding the pulverized product as a result of the pulverization step, the particle size, crystal shape, crystallinity, viscosity average polymerization degree, cation requirement, and sedimentation rate were measured. The measurement method was as follows.

(Measuring method)
1. Amount of functional group (phosphate group) introduced In the embodiment of the present invention, the amount of functional group introduced is phosphorus after sufficiently washing away excess sodium hydroxide obtained by the <washing / alkali treatment step> described later. The oxidized cellulose fiber was dispersed in ion-exchanged water to obtain a cellulose fiber-containing slurry having a solid content concentration of 0.2% by mass, and then measured by treatment with an ion-exchange resin and titration with an alkali.

  In the treatment with an ion exchange resin, 1/10 by volume of a strongly acidic cation exchange resin (Amberjet (trademark) 1024: Organo Corporation, conditioned) is added to a 0.2% by mass cellulose fiber-containing slurry. Time shaking treatment was performed. Thereafter, the mixture was poured onto a mesh having an opening of 90 μm to separate the resin and the slurry. In titration using an alkali, a change in the value of electrical conductivity exhibited by the slurry was measured while adding a 0.1N aqueous sodium hydroxide solution to the slurry after ion exchange.

  That is, the alkali amount (mmol) required in the first region of the curve shown in FIG. 1 was divided by the solid content (g) in the titration target slurry to obtain the functional group introduction amount (mmol / g).

2. Viscosity average degree of polymerization (before pulverization process, after pulverization process)
The viscosity of the cellulose material (cellulose fibers and cellulose powder) before and after the pulverization step was measured according to the paper pulp test method Japan Tappi T230 by the Japan Paper Pulp Technology Association. Further, the viscosity of only the dispersion medium was measured by a blank test to obtain a blank viscosity. The specific viscosity ([η]) was calculated using the following formula (I) by subtracting 1 from the numerical value obtained by dividing the viscosity of the cellulose material before and after the pulverization step by the blank viscosity to obtain the specific viscosity (ηsp).
[Η] = ηsp / (c (1 + 0.28 × ηsp)) (I)
Here, c in the formula (I) indicates a cellulose concentration (mass basis) at the time of viscosity measurement.

And the polymerization degree (DP) in this invention was computed from following formula (II).
DP = 1.75 × [η] (II)
Since this degree of polymerization is an average degree of polymerization measured by the viscosity method, it is also referred to as “viscosity average degree of polymerization”.

3. The particle size distribution of the pulverized product was measured using a particle size laser analysis / scattering type particle size distribution measuring device (Microtrac Bell, model number MT3300EXII) to obtain a 50% particle size (D50).

4). Whether crystalline form ground material is taken cellulose I type crystal structure, the diffraction profile obtained by the wide-angle X-ray diffraction photographs using CuKα (λ = 1.5418Å) was monochromatic with graphite, 2 [Theta] = 14 ° It was identified by whether or not it has typical peaks at two positions near 17 ° or less and 2θ = 22 ° or more and 23 ° or less.

5). The degree of crystallinity of the pulverized crystallinity was determined by measuring the X-ray diffraction profile and using the pattern from the pattern (see Non-Patent Document 1).

6). Cation requirement The cation requirement of the cellulose powder according to the embodiment of the present invention was determined as follows. The pulverized product (each powder) was dispersed in ion-exchanged water to prepare a slurry having a concentration of 1% by mass. About 95 g of a 0.001N poly (diallyldimethylammonium chloride) (p-DADMAC) solution was added to about 5 g of this slurry, and stirred for 2 hours. The resulting slurry was filtered to obtain a filtrate. The cation required amount of 10 mL of the filtrate was titrated to a potential zero point with 0.001 N potassium potassium sulfate (PVSK) using a PCD meter (Spectres Co., Ltd.). Further, a mixture of 5 g of ion-exchanged water and p-DADMAC was used as a blank. The amount of PVSK (mL) required for the titration of the sample was x, the amount of PVSK (mL) required for the titration of the blank was y, and the required amount of cation was calculated using the following formula (III).
Cation requirement (meq / g) = [(y−x) /1000×0.001] / (1% slurry removal amount × 0.01 × 0.1) (III)

7). A settling rate pulverized product (each powder) was dispersed in ion-exchanged water to prepare a slurry having a concentration of 1% by mass. About 100 mL of this slurry was placed in a 110 mL screw tube bottle and stirred. Thereafter, the standing was started at the same time, and the degree of sedimentation after 3 minutes was compared visually. The evaluation indicates that the slower the sedimentation rate, the better the dispersibility, and it was expressed using the symbols ◯, Δ, and X in order from the slower sedimentation rate.

(Example 1)
<Phosphorylation reaction process>
Pulp sheet (solid content: 93% by mass, basis weight: 208g / m ²⁾ measured by Oji Paper Co., Ltd. softwood bleached kraft pulp (hereinafter also simply referred to as NBKP), measured according to Japanese Industrial Standard JIS P 8121 Canadian standard freeness (CSF) was 700 ml). A mixed aqueous solution of ammonium dihydrogen phosphate and urea is added to 100 parts by mass (absolute dry weight conversion) of the above NBKP pulp sheet, and 45 parts by mass of ammonium dihydrogen phosphate, 120 parts by mass of urea, and 150 ion-exchanged water. The mixture was compressed to a mass part to obtain a chemical solution impregnated pulp. The obtained chemical-impregnated pulp was dried and heat-treated for 200 seconds with a hot air dryer at 165 ° C. to introduce phosphoric acid groups into cellulose in the pulp to obtain phosphorylated cellulose fibers A.

<Washing and alkali treatment process>
Ion exchange water was poured into the obtained phosphorylated cellulose fiber A, and the mixture was stirred and dispersed uniformly, followed by filtration and dehydration to obtain a dehydrated sheet. Excess chemicals were sufficiently washed away by repeating the operations of ion-exchanged water injection, uniform dispersion by stirring, and filtration / dehydration for the obtained dehydration sheet. Next, ion-exchanged water is poured into the dehydrated sheet from which the excess chemical solution has been sufficiently washed away, diluted with ion-exchanged water so that the concentration of phosphorylated cellulose fibers dispersed in water becomes 2% by mass, and stirred. While adding 1N (1N) aqueous sodium hydroxide solution little by little, a slurry having a pH of 12 ± 0.2 was obtained. Thereafter, the slurry was dehydrated to obtain a dehydrated sheet. Again, excessive sodium hydroxide was sufficiently washed away by repeating the operation of pouring ion-exchanged water into the obtained dehydrated sheet, uniform dispersion by stirring, and filtration and dehydration to obtain phosphorylated cellulose fibers B.

<Crushing process>
The obtained phosphorylated cellulose fiber B was dried to obtain a dry sheet. The dried sheet is cut into a size of about 1 cm square by a Willy mill, and then pulverized at a rotational speed of 7000 rpm using an impact pulverizer turbo mill T-400 standard type (manufactured by Freund Turbo). A pulverized product (phosphorylated cellulose powder 1) was obtained.

(Example 2)
In the same manner as in Example 1, a pulverized product (phosphorylated cellulose powder 1) was obtained. Next, the obtained pulverized product (phosphorylated cellulose powder 1) was further pulverized at a pulverization pressure of 0.6 MPa using a multinojet mill MJ2070 (manufactured by Taiheiyo Kiko Co., Ltd.) to obtain a pulverized product (phosphorylated cellulose powder). 2) was obtained.

Example 3
In the same manner as in Example 1, phosphorylated cellulose fiber B was obtained. Subsequently, the obtained phosphorylated cellulose fiber B was further pulverized using a cutter mill RC-250 (manufactured by Kiko Co., Ltd.), and the portion passing through the 0.5 mmφ screen was collected and pulverized (phosphorylated cellulose powder 3) Got.

(Example 4)
<Phosphorylation reaction process>
In the pulp as in Example 1, except that the composition was changed to 40 parts by mass of ammonium dihydrogen phosphate, 120 parts by mass of urea, and 150 parts by mass of ion-exchanged water in the pressing in the phosphorylation reaction step of Example 1. Phosphoric acid groups were introduced into the cellulose to obtain phosphorylated cellulose fibers C.

<Washing and alkali treatment process>
Phosphorylated cellulose fiber D was obtained from phosphorylated cellulose fiber C by the same procedure as the washing and alkali treatment step of Example 1 for obtaining phosphorylated cellulose fiber B from phosphorylated cellulose fiber A.

<Crushing process>
The obtained phosphorylated cellulose fiber D was pulverized using a cutter mill RC-250 (manufactured by Yoshiko Co., Ltd.), and the portion passing through the 0.5 mmφ screen was collected to obtain a pulverized product (phosphorylated cellulose powder 4).

(Example 5)
<Phosphorylation reaction process>
In the pulp as in Example 1, except that the composition was changed to 20 parts by mass of ammonium dihydrogen phosphate, 120 parts by mass of urea, and 150 parts by mass of ion-exchanged water in the squeezing in the phosphorylation reaction step of Example 1. A phosphoric acid group was introduced into the cellulose to obtain phosphorylated cellulose fiber E.

<Washing and alkali treatment process>
Phosphorylated cellulose fiber F was obtained from phosphorylated cellulose fiber E by the same procedure as the washing and alkali treatment step of Example 1 for obtaining phosphorylated cellulose fiber B from phosphorylated cellulose fiber A.

<Crushing process>
In the same manner as in the pulverization step of Example 1, a pulverized product (phosphorylated cellulose powder 5) was obtained from phosphorylated cellulose fiber F.

(Example 6)
<Carboxymethylation reaction process>
As in Example 1, a pulp sheet made of NBKP manufactured by Oji Paper Co., Ltd. was used as a raw material. 225 parts by mass of a 12% aqueous sodium hydroxide solution was added to 100 parts by mass of the NBKP pulp sheet (in terms of absolute dry mass), and the mixture was stirred at room temperature for 5 minutes. Thereafter, 72 parts by mass of sodium monochloroacetate was added, and the mixture was heated to 60 ° C. and reacted for 60 minutes.

<Washing process>
Ion exchange water was poured into the obtained carboxymethylated fiber, stirred and dispersed uniformly, and then filtered and dehydrated to obtain a dehydrated cake. Excess chemicals and by-products were sufficiently washed away by repeating the operations of ion-exchanged water injection, uniform dispersion by stirring, and filtration dehydration for the obtained dehydrated cake.

<Crushing process>
The obtained carboxymethylated fiber was dried to obtain a dry cake. The dried cake is cut into a size of about 1 cm square by a Willy mill, and then pulverized at a rotational speed of 5000 rpm using an impact type pulverizer Turbo Mill T-400 (manufactured by Freund Turbo). A pulverized product (carboxymethylated cellulose powder 1) was obtained.

(Example 7)
The reaction step and the washing step were performed in the same manner as in Example 6 to obtain a dry cake of carboxymethylated fibers. The dried cake was cut into a size of about 1 cm square in the same manner as in Example 6 and then pulverized at a rotational speed of 4000 rpm using an impact pulverizer turbo mill T-400 standard type (made by Freund Turbo). A product (carboxymethylated cellulose powder 2) was obtained.

(Comparative Example 1)
Pulp sheet (solid content 93% by mass, basis weight 1300 g / m ² ) made from broad-leaved tree bleached kraft pulp (hereinafter also referred to simply as LBKP) manufactured by Cenirose Nipo-Brasireira S.A. Canadian standard freeness (CSF) (550 ml) when measured according to 8121) was used as a raw material. There is no hydrophilic functional group other than the hydrophilic functional group derived from cellulose in this pulp. The LBKP was pulverized with a cutter mill RC-250 (manufactured by Yoshiko Co., Ltd.), and the 0.5 mmφ screen passage was collected to obtain a pulverized product (cellulose powder 6).

(Comparative Example 2)
In the same manner as in Comparative Example 1, a pulverized product (cellulose powder 6) was obtained. Subsequently, the obtained pulverized product (cellulose powder 6) was further pulverized at a rotational speed of 7000 rpm using an impact pulverizer Turbo Mill T-400 to obtain a pulverized product (cellulose powder 7).

(Measurement result)
Table 1 shows the conditions and measurement results of Examples and Comparative Examples.

  The phosphorylated cellulose powder obtained by the methods of Examples 1 to 5 and the carboxymethylated cellulose powder obtained by the methods of Examples 6 and 7 were compared with the cellulose powder obtained by the methods of Comparative Examples 1 and 2. In addition, the value of the required cation amount was high, and the evaluation result of the sedimentation rate was excellent. From this result, the hydrophilic functional group-containing cellulose powder having a phosphate group or a carboxymethyl group introduced is superior in adsorption performance by ionic bonds, compared to a cellulose powder having no hydrophilic functional group introduced, Furthermore, it was suggested that the dispersibility in the liquid is excellent.

  According to the present invention, it is possible to provide a cellulose powder having high adsorption performance and excellent dispersibility in a liquid. The cellulose powder according to the embodiment of the present invention is not particularly limited in use. For example, the cellulose powder can be suitably used as, for example, a separation material for an ion exchange resin.

Examples of preferred embodiments of the present invention are shown below.
1. A cellulose powder containing an introduced hydrophilic functional group, wherein the introduction amount of the hydrophilic functional group is 0.1 mmol / g or more and 3.0 mmol / g or less, and a 50% particle diameter is 1 μm or more and 100 μm. Cellulose powder characterized by:
2. The required cation amount is 0.1 meq / g or more and 5 meq / g or less. Cellulose powder described in 1.
3. The viscosity average degree of polymerization is 500 or more. Or 2. Cellulose powder described in 1.
4). The cellulose I type crystallinity of the cellulose powder is 50% or more. To 3. Cellulose powder according to any of the above.
5). The hydrophilic functional group is at least one selected from the group consisting of a phosphate group, a carboxy group, a hydroxy group and a sulfone group. To 4. Cellulose powder according to any of the above.
6). Including a step of introducing a hydrophilic functional group into a cellulose raw material, and a step of obtaining a cellulose powder by pulverizing the cellulose raw material into which the hydrophilic functional group has been introduced, wherein the pulverization is a cutting pulverizer, an impact type A method for producing a cellulose powder, which is performed using at least one pulverizer selected from the group consisting of a pulverizer and an airflow pulverizer.
7). A step of introducing a hydrophilic functional group into the cellulose raw material, and a step of pulverizing the cellulose raw material into which the hydrophilic functional group has been introduced to obtain a cellulose powder. The pulverization is performed using a cutting pulverizer. Cellulose powder, characterized in that it is a multi-stage treatment comprising: a treatment to be performed; and a subsequent treatment to be performed using at least one pulverizer selected from the group consisting of an impact pulverizer and an airflow pulverizer Manufacturing method.
8). 5. The cellulose raw material contains lignocellulose. Or 7. The manufacturing method of the cellulose powder of description.

Claims (8)

  A cellulose powder containing an introduced hydrophilic functional group, wherein the introduction amount of the hydrophilic functional group is 0.1 mmol / g or more and 3.0 mmol / g or less, and a 50% particle diameter is 1 μm or more and 100 μm. Cellulose powder characterized by:   The cellulose powder according to claim 1, wherein the cation requirement is 0.1 meq / g or more and 5 meq / g or less.   Viscosity average polymerization degree is 500 or more, The cellulose powder of Claim 1 or 2 characterized by the above-mentioned.   The cellulose powder according to any one of claims 1 to 3, wherein a cellulose I type crystallinity of the cellulose powder is 50% or more.   The cellulose powder according to any one of claims 1 to 4, wherein the hydrophilic functional group is at least one selected from the group consisting of a phosphate group, a carboxy group, a hydroxy group, and a sulfone group. . Introducing a hydrophilic functional group into the cellulose raw material;
Pulverizing the cellulose raw material introduced with the hydrophilic functional group to obtain a cellulose powder;
Including
The method for producing cellulose powder, wherein the pulverization is performed using at least one pulverizer selected from the group consisting of a cutting pulverizer, an impact pulverizer, and an airflow pulverizer. Introducing a hydrophilic functional group into the cellulose raw material;
Pulverizing the cellulose raw material introduced with the hydrophilic functional group to obtain a cellulose powder;
Including
The pulverization includes a process performed using a cutting pulverizer and a subsequent process performed using at least one pulverizer selected from the group consisting of an impact pulverizer and an airflow pulverizer. A method for producing a cellulose powder, which is a multistage treatment.   The said cellulose raw material contains lignocellulose, The manufacturing method of the cellulose powder of Claim 6 or 7 characterized by the above-mentioned.

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