JP2021098174A - Water treatment agent containing carboxymethylated cellulose, filter material using the same, and water-in-oil removal method - Google Patents

Abstract

To provide a water treatment agent excellent in moisture adsorption, and excellent in filtration performance when used as a filter material.SOLUTION: In a water treatment agent containing carboxymethylated cellulose in which a carboxymethyl substitution degree is 0.50 or less, and crystallinity of cellulose type I is 50% or higher, and further, in the carboxymethylated cellulose, an anionization degree is 0.00 meq/g or more and 1.00 meq/g or less, and a viscosity (30 rpm, 25°C) when forming water dispersion with a solid content of 1%(W/V) is 30.0 mPa-s or less.SELECTED DRAWING: None

Description

The present invention relates to a water treatment agent containing carboxymethylated cellulose, a filter medium using the same, and a method for removing water in oil.

In food manufacturing, textile processing, machining, petroleum refining, etc., in waste liquid treatment including waste oil, treatment for separating oil and water is performed.

Such oil-water separation methods include separation by a flocculant, adsorption separation, centrifugation, pressure flotation separation, ionization flotation, coarse-grained separation by a corelesser (for example, Patent Document 1), and separation by a microbial subcommittee. Are known.

Japanese Unexamined Patent Publication No. 2006-198483

However, in the case of the separation method using a coagulant, there is a problem that not only the cost is high on a daily basis, but also the treatment of the filtered coagulum is laborious and costly. In addition, a machine such as a centrifuge and a dissolved air flotation separation may be effective in a large amount and in a large facility, but there is a problem that it is difficult to install them in a limited space. .. Further, in the electrolytic levitation method, in order to perform stable oil-water separation, there is a problem that control is complicated, such as changing the applied power according to the electric conductivity of the treatment liquid and the treatment amount.

Further, in the corelesser method as shown in Patent Document 1, since a filter having a network structure of ultrafine fibers is used, there is a problem that clogging always becomes a problem in maintenance management.

Therefore, it is an object of the present invention to provide a water treatment agent which is excellent in adsorbability of water and excellent in filtration performance when used as a filter material.

As a result of diligent efforts to achieve the above object, the present inventors have made water containing carboxymethylated cellulose having a degree of carboxymethyl substitution of 0.50 or less and a degree of crystallinity of cellulose type I of 50% or more. We have found that the above problems can be solved by using a treatment agent, and have arrived at the present invention.

That is, the present invention is the following (1) to (6).
(1) A water treatment agent containing carboxymethylated cellulose having a degree of carboxymethyl substitution of 0.50 or less and a degree of crystallization of cellulose type I of 50% or more.
(2) The water treatment agent according to (1), wherein the carboxymethylated cellulose has a degree of anionization of 0.00 meq / g or more and 1.00 meq / g or less.
(3) The viscosity (30 rpm, 25 ° C.) of the carboxymethylated cellulose as an aqueous dispersion having a solid content of 1% (W / V) is 30.0 mPa · s or less. The water treatment agent according to any one of (1) to (2).
(4) Any of (1) to (3), wherein the carboxymethylated cellulose has a structure in which a carboxymethyl group is ether-bonded to a part of hydroxyl groups in a glucose residue constituting the cellulose. The water treatment agent described in.
(5) A filter medium containing the water treatment agent according to any one of (1) to (4).
(6) A method for removing water in oil, which comprises the following steps (A) to (B).
Step (A): A step of bringing the water treatment agent according to any one of (1) to (4) into contact with an oily composition containing water.
Step (B): A step of filtering out the water treatment agent from the oily composition.

According to the present invention, it is possible to provide a water treatment agent having excellent water adsorption property and excellent filtration performance when used as a filter material.

That is, the present invention is a water treatment agent containing carboxymethylated cellulose having a degree of carboxymethyl substitution of 0.50 or less and a degree of crystallization of cellulose type I of 50% or more.

<Carboxymethylated cellulose>
The present invention relates to a water treatment agent containing carboxymethylated cellulose. Carboxymethylated cellulose has a structure in which some of the hydroxyl groups in the glucose residues constituting the cellulose are ether-bonded to the carboxymethyl group. The carboxymethylated cellulose may take the form of a salt, and the carboxymethylated cellulose used in the present invention also includes a salt of the carboxymethylated cellulose. Examples of the salt of carboxymethylated cellulose include metal salts such as sodium carboxymethyl cellulose salt.

The carboxymethylated cellulose used in the present invention preferably maintains at least a part of its fibrous shape even when dispersed in water. That is, when the aqueous dispersion of carboxymethylated cellulose is observed with an electron microscope or the like, it is preferable that a fibrous substance can be observed. Moreover, when the carboxymethylated cellulose is measured by X-ray diffraction, the peak of the cellulose type I crystal can be observed.

The carboxymethylated cellulose used in the present invention has a carboxymethyl substitution degree of cellulose per anhydrous glucose unit of 0.50 or less, preferably 0.40 or less. If the degree of substitution exceeds 0.50, dissolution in water is likely to occur, the fiber morphology cannot be maintained in water, and the effect of imparting shape retention and the like may be reduced. In order to obtain the effects of carboxymethylated cellulose such as shape retention and water absorption, it is necessary to have a certain degree of carboxymethyl substitution. For example, when the degree of carboxymethyl substitution is less than 0.02, Depending on the application, the advantage of introducing a carboxymethyl group may not be obtained. Therefore, the degree of carboxymethyl substitution is preferably 0.02 or more, more preferably 0.05 or more, further preferably 0.10 or more, still more preferably 0.15 or more. , 0.20 or more, more preferably 0.25 or more. In particular, in the range of carboxymethyl substitution degree of 0.20 or more and 0.50 or less, obtaining carboxymethylated cellulose having a cellulose type I crystallinity of 50% or more, which will be described later, is particularly a conventional water medium. Although it was difficult by the method, the present inventors have, for example, by the production method described later, that the degree of carboxymethyl substitution is 0.20 or more and 0.50 or less, the crystallinity of cellulose type I is 50% or more, and the quality. It has been found that it is possible to produce a carboxymethylated cellulose that is stable (provides a low-viscosity dispersion and / or has a small absolute value of anionization degree) and is difficult to form agglomerates. The degree of carboxymethyl substitution can be adjusted by controlling the amount of the carboxymethylating agent to be reacted, the amount of the mercerizing agent, the composition ratio of water and the organic solvent, and the like.

In the present invention, the anhydrous glucose unit means individual anhydrous glucose (glucose residue) constituting cellulose. The degree of carboxymethyl substitution (also referred to as the degree of etherification) is the ratio of hydroxyl groups in the glucose residues constituting cellulose that are substituted with carboxymethyl ether groups (carboxymethyl per glucose residue). The number of ether groups) is shown. The degree of carboxymethyl substitution may be abbreviated as DS.

The method for measuring the degree of carboxymethyl substitution is as follows:
Weigh approximately 2.0 g of the sample and place it in an Erlenmeyer flask with a 300 mL stopper. 100 mL of a solution prepared by adding 100 mL of special grade concentrated nitric acid to 1000 mL of methanol nitrate is added, and the mixture is shaken for 3 hours to convert the salt of carboxymethylated cellulose (CMC) into H-CMC (hydrogen-type carboxymethylated cellulose). Weigh 1.5 to 2.0 g of the absolutely dry H-CMC and place it in an Erlenmeyer flask with a 300 mL stopper. Wet H-CMC with 15 mL of 80% methanol, add 100 mL of 0.1N-NaOH, and shake at room temperature for 3 hours. Using phenolphthalein as an indicator, _{back titrate excess NaOH with 0.1 N-H 2} SO ₄ , and calculate the degree of carboxymethyl substitution (DS value) by the following formula.
A = [(100 × F'-0.1N-H ₂ SO ₄ (mL) × F) × 0.1] / (absolute dry mass (g) of H-CMC)
Degree of substitution of carboxymethyl = 0.162 × A / (1-0.058 × A)
F': 0.1N-H ₂ SO ₄ factor F: 0.1N-NaOH factor.

The crystallinity of cellulose in the carboxymethylated cellulose used in the present invention is more preferably 50% or more, and more preferably 60% or more for crystal type I. By adjusting the crystallinity within the above range, it becomes possible to obtain a high effect such as imparting shape retention by the carboxymethylated cellulose. The crystallinity of cellulose can be controlled by the concentration of the mercerizing agent, the temperature during treatment, and the degree of carboxymethylation. Since a high concentration of alkali is used in mercerization and carboxymethylation, type I crystals of cellulose are easily converted to type II, but they are modified by adjusting the amount of alkali (mercerizing agent) used. By adjusting the degree, the desired crystallinity can be maintained. The upper limit of the crystallinity of cellulose type I is not particularly limited. In reality, about 90% is considered to be the upper limit.

The method for measuring the crystallinity of cellulose type I of carboxymethylated cellulose is as follows:
The sample is placed on a glass cell and measured using an X-ray diffraction measuring device (LabX XRD-6000, manufactured by Shimadzu Corporation). The crystallinity is calculated using a method such as Segal, and the diffraction intensity of the 002 surface at 2θ = 22.6 ° and 2θ = are based on the diffraction intensity of 2θ = 10 ° to 30 ° in the X-ray diffraction diagram. It is calculated by the following formula from the diffraction intensity of the amorphous portion of 18.5 °.

Xc = (I002c ― Ia) / I002c × 100
Xc = Cellulose type I crystallinity (%)
I002c: 2θ = 22.6 °, diffraction intensity of 002 surface Ia: 2θ = 18.5 °, diffraction intensity of amorphous part.

In general, carboxymethylated cellulose is obtained by treating cellulose with an alkali (mercerization), and then reacting the obtained mercerized cellulose (also referred to as alkali cellulose) with a carboxymethylating agent (also referred to as etherifying agent). It can be manufactured by.

The degree of anionization (also referred to as anion charge density) of the carboxymethylated cellulose is preferably 0.00 meq / g or more and 1.00 meq / g or less. In the present invention, the method for measuring the degree of anionization is as follows:

Carboxymethylated cellulose is dispersed in water to prepare an aqueous dispersion having a solid content of 10 g / L, and the mixture is stirred with a magnetic stirrer at 1000 rpm for a whole day and night. After diluting the obtained slurry to 0.1 g / L, 10 ml was collected, titrated with 1/1000 normal diallyldimethylammonium chloride (DADMAC) using a flow current detector (Mutek Particle Charge Detector 03), and flowed. Using the amount of DADMAC added until the current becomes zero, calculate the degree of anionization by the following formula:
q = (V × c) / m
q: Degree of anionization (meq / g)
V: Addition amount (L) of DADMAC until the flow current becomes zero
c: DADMAC concentration (meq / L)
m: Mass (g) of carboxymethylated cellulose in the measurement sample.

In the present specification, the "degree of anionization" corresponds to the equivalent amount of DADMAC required to neutralize an anionic group in a unit mass of carboxymethyl cellulose, as can be seen from the above measurement method, and is a unit. Corresponds to the equivalent of anions per mass of carboxymethylated cellulose.

The degree of anionization of carboxymethylated cellulose is preferably 0.00 meq / g or more and 1.00 meq / g or less, more preferably 0.00 meq / g or more and 0.80 meq / g or less, and 0.00 meq / g or more and 0.60 meq or more. / G or less is more preferable. Carboxymethylated cellulose having a degree of anionization in such a range has a carboxymethyl group that is uniform throughout the cellulose rather than locally, as compared with carboxymethylated cellulose having a degree of anionization higher than 1.00 meq / g. It is considered that the effect peculiar to carboxymethylated cellulose, such as shape retention and water absorption, can be obtained more stably.

Carboxymethylated cellulose preferably exhibits a low viscosity when water is used as a dispersion medium as a dispersion (aqueous dispersion). In the present invention, the method for measuring viscosity is as follows:
Carboxymethylated cellulose is measured in a 1000 ml glass beaker and dispersed in 900 ml of distilled water to prepare an aqueous dispersion having a solid content of 1% (w / v). The aqueous dispersion is stirred at 25 ° C. using a stirrer at 600 rpm for 3 hours. Then, according to the method of JIS-Z-8803, a B-type viscometer (manufactured by Toki Sangyo Co., Ltd.) was used to obtain No. The viscosity after 3 minutes is measured at 1 rotor / rotation speed of 30 rpm.

The viscosity of the carboxymethylated cellulose is preferably 30.0 mPa · s or less, more preferably 20.0 mPa · s or less, and even more preferably 10.0 mPa · s or less. In such low-viscosity carboxymethylated cellulose, the carboxymethyl group is considered to be introduced uniformly throughout the cellulose rather than locally, and the effects peculiar to the carboxymethylated cellulose, for example, shape retention, It is considered that water absorption and the like can be obtained more stably. The lower limit of the viscosity is not particularly limited. In reality, it is considered that the lower limit is about 1.0 mPa · s.

The carboxymethylated cellulose may be in the form of a dispersion obtained after production, but may be dried if necessary, or may be redispersed in water. The drying method is not limited, but for example, freeze-drying method, spray drying method, shelf-type drying method, drum drying method, belt drying method, thinly stretched drying method on a glass plate, etc. , A known method such as a heating fan type vacuum drying method can be used. After drying, it may be crushed with a cutter mill, a hammer mill, a pin mill, a jet mill or the like, if necessary. Further, the method of redispersion in water is not particularly limited, and a known disperser can be used.

<Manufacturing method of carboxymethylated cellulose>
In general, carboxymethylated cellulose is obtained by treating cellulose with an alkali (mercerization), and then reacting the obtained mercerized cellulose (also referred to as alkali cellulose) with a carboxymethylating agent (also referred to as etherifying agent). It can be manufactured by.

The carboxymethylated cellulose of the present invention having a degree of carboxymethyl substitution of 0.50 or less and a degree of crystallization of cellulose type I of 50% or more is not limited to this, and is, for example, mercerization (alkaline treatment of cellulose). Is carried out under a solvent mainly containing water, and then carboxymethylation (also referred to as etherification) is carried out under a mixed solvent of water and an organic solvent. The carboxymethylated cellulose thus obtained can be obtained by using a conventional water medium method (a method in which both marcelation and carboxymethylation are carried out using water as a solvent) and a solvent method (both marcelation and carboxymethylation are carried out using an organic solvent). Compared with the carboxymethylated cellulose obtained by the main solvent method), it shows a lower viscosity when made into an aqueous dispersion, the absolute value of the degree of anionization is smaller (closer to 0), and the shopper reigler. It has a high degree of water solubility and is difficult to form a lump when it is made into an aqueous dispersion. In addition, the above method has an advantage that the effective utilization rate of the carboxymethylating agent is high. By the above method, the viscosity of an aqueous dispersion having a carboxymethyl substitution degree of 0.50 or less, a cellulose type I crystallinity of 50% or more, and a solid content of 1% (w / v) ( It is possible to produce carboxymethylated cellulose having a temperature of 30.0 mPa · s or less (30 rpm, 25 ° C.).

Further, by the above method, the degree of carboxymethyl substitution is 0.50 or less, the degree of crystallization of cellulose type I is 50% or more, and the degree of anionization is 0.00meq / g or more and 1.00meq / g or less. Certain carboxymethylated celluloses can be produced.

<Cellulose>
In the present invention, cellulose means a polysaccharide having a structure in which D-glucopyranose (simply referred to as “glucose residue” or “anhydrous glucose”) is linked by β-1,4 bonds. Cellulose is generally classified into natural cellulose, regenerated cellulose, fine cellulose, microcrystalline cellulose excluding amorphous regions, etc., based on the origin, manufacturing method, and the like. In the present invention, any of these celluloses can be used as a raw material for mercerized cellulose, but in order to maintain 50% or more of cellulose type I crystallinity in carboxymethylated cellulose, cellulose type I type can be used. It is preferable to use cellulose having a high degree of crystallinity as a raw material. The crystallinity of cellulose type I of the raw material cellulose is preferably 70% or more, and more preferably 80% or more. The method for measuring the crystallinity of cellulose type I is as described above.

Examples of natural cellulose include bleached pulp or unbleached pulp (bleached wood pulp or unbleached wood pulp); linters, purified linters; cellulose produced by microorganisms such as acetic acid bacteria. The raw material of bleached pulp or unbleached pulp is not particularly limited, and examples thereof include wood, cotton, straw, bamboo, hemp, jute, and kenaf. Further, the method for producing bleached pulp or unbleached pulp is not particularly limited, and a mechanical method, a chemical method, or a method in which the two are combined may be used. The bleached pulp or unbleached pulp classified according to the production method includes, for example, mechanical pulp (thermomechanical pulp (TMP), crushed wood pulp), chemical pulp (conifer unbleached sulphite pulp (NUSP), conifer bleached sulphite pulp (NBSP). ) And the like, unbleached coniferous kraft pulp (NUKP), bleached coniferous kraft pulp (NBKP), unbleached broadleaf kraft pulp (LUKP), kraft pulp such as broadleaf bleached kraft pulp (LBKP)) and the like. Further, dissolved pulp may be used in addition to the pulp for papermaking. Dissolving pulp is chemically refined pulp, which is mainly dissolved in chemicals and used as a main raw material for artificial fibers, cellophane, and the like.

Examples of the regenerated cellulose include those obtained by dissolving cellulose in some solvent such as a cuprammonium solution, a cellulose zantate solution, and a morpholine derivative, and spinning it again. The fine cellulose includes those obtained by depolymerizing a cellulosic material such as natural cellulose or regenerated cellulose (for example, acid hydrolysis, alkali hydrolysis, enzymatic decomposition, blasting treatment, vibration ball mill treatment, etc.). An example is one obtained by mechanically processing the cellulosic material.

<Mercerization>
The above-mentioned cellulose is used as a raw material, and mercerized cellulose (also referred to as alkaline cellulose) is obtained by adding a mercerizing agent (alkali). According to the method described herein, water is mainly used as the solvent in this mercerization reaction, and the carboxymethylation of the present invention is carried out by using a mixed solvent of an organic solvent and water in the next carboxymethylation. Cellulose can be obtained economically. The carboxymethylated cellulose thus obtained exhibits a low viscosity when made into an aqueous dispersion. Further, the carboxymethylated cellulose thus obtained has a small absolute value of the degree of anionization. In addition, the carboxymethylated cellulose thus obtained has a high degree of Shopper-Regula free water. Further, the carboxymethylated cellulose thus obtained has less formation of lumps when made into an aqueous dispersion (that is, a small proportion of filtration residues is generated).

The term "water-based solvent" as a solvent mainly uses water means a solvent containing water in a proportion higher than 50% by mass. The water in the solvent mainly containing water is preferably 55% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, and more preferably 80% by mass or more. It is more preferably 90% by mass or more, still more preferably 95% by mass or more. Particularly preferably, the solvent mainly containing water is 100% by mass (that is, water) of water. The higher the proportion of water during mercerization, the more the advantage is that the carboxymethyl group is uniformly introduced by the cellulose. Examples of the solvent other than water (used by mixing with water) in the solvent mainly containing water include an organic solvent used as a solvent in the subsequent carboxymethylation. For example, alcohols such as methanol, ethanol, N-propyl alcohol, isopropyl alcohol, N-butanol, isobutanol and tertiary butanol, ketones such as acetone, diethyl ketone and methyl ethyl ketone, and dioxane, diethyl ether, benzene and dichloromethane. And the like, these alone or a mixture of two or more kinds can be added to water in an amount of less than 50% by mass and used as a solvent for marcel formation. The organic solvent in the solvent mainly containing water is preferably 45% by mass or less, more preferably 40% by mass or less, further preferably 30% by mass or less, still more preferably 20% by mass or less. , More preferably 10% by mass or less, further preferably 5% by mass or less, and even more preferably 0% by mass.

Examples of the mercerizing agent include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide, and one or a combination of two or more of these can be used. The mercerizing agent is not limited to this, but these alkali metal hydroxides are used in the reactor as an aqueous solution of, for example, 1 to 60% by mass, preferably 2 to 45% by mass, and more preferably 3 to 25% by mass. Can be added.

The amount of the mercerizing agent used is not particularly limited as long as it can achieve both a carboxymethyl substitution degree of 0.50 or less in carboxymethylated cellulose and a crystallization degree of cellulose type I of 50% or more. In one embodiment, it is preferably 0.1 mol or more and 2.5 mol or less, more preferably 0.3 mol or more and 2.0 mol or less, and 0.4 mol or more, with respect to 100 g (absolutely dry) of cellulose. It is more preferably mol or more and 1.5 mol or less.

The amount of the solvent mainly containing water at the time of mercerization is not particularly limited as long as it can be stirred and mixed with the raw materials, but is preferably 1.5 to 20 times by mass with respect to the cellulose raw material, and 2 to 10 times. More preferably, it is multiplied by mass.

In the mercerization treatment, the bottoming material (cellulose) and a solvent mainly composed of water are mixed, and the temperature of the reactor is adjusted to 0 to 70 ° C., preferably 10 to 60 ° C., more preferably 10 to 40 ° C. Then, an aqueous solution of the mercerizing agent is added, and the mixture is stirred for 15 minutes to 8 hours, preferably 30 minutes to 7 hours, and more preferably 30 minutes to 3 hours. As a result, mercerized cellulose (alkaline cellulose) is obtained.

The pH at the time of mercerization is preferably 9 or more, whereby the mercerization reaction can proceed. The pH is more preferably 11 or more, still more preferably 12 or more, and may be 13 or more. The upper limit of pH is not particularly limited.

Mercerization can be carried out using a reactor capable of mixing and stirring each of the above components while controlling the temperature, and various reactors conventionally used for the mercerization reaction can be used. For example, a batch type agitator in which two shafts agitate and each of the above components is mixed is preferable from the viewpoint of both uniform mixing property and productivity.

<Carboxymethylation>
Carboxymethylated cellulose is obtained by adding a carboxymethylating agent (also referred to as an etherifying agent) to mercerized cellulose. According to the method described in the present specification, carboxymethylation of the present invention is carried out by using water as a main solvent during mercerization and using a mixed solvent of water and an organic solvent during carboxymethylation. Cellulose can be obtained economically. The carboxymethylated cellulose thus obtained exhibits a low viscosity when made into an aqueous dispersion. Further, the carboxymethylated cellulose thus obtained has a small absolute value of the degree of anionization. In addition, the carboxymethylated cellulose thus obtained has a high degree of Shopper-Regula free water. Further, the carboxymethylated cellulose thus obtained has less formation of lumps when made into an aqueous dispersion (that is, a small proportion of filtration residues is generated).

Examples of the carboxymethylating agent include monochloroacetic acid, sodium monochloroacetic acid, methyl monochloroacetic acid, ethyl monochloroacetic acid, isopropyl monochloroacetate and the like. Of these, monochloroacetic acid or sodium monochloroacetate is preferable in terms of availability of raw materials.

The amount of the carboxymethylating agent used is not particularly limited as long as it can achieve both a carboxymethyl substitution degree of 0.50 or less in carboxymethylated cellulose and a crystallization degree of cellulose type I of 50% or more. In one embodiment, it is preferably added in the range of 0.5 to 1.5 mol per anhydrous glucose unit of cellulose. The lower limit of the above range is more preferably 0.6 mol or more, further preferably 0.7 mol or more, and the upper limit is more preferably 1.3 mol or less, still more preferably 1.1 mol or less. The carboxymethylating agent can be added to the reactor as, for example, an aqueous solution of 5 to 80% by mass, more preferably 30 to 60% by mass, without limitation. Further, it can be added in a powder state without being dissolved.

The molar ratio of the mercelling agent to the carboxymethylating agent (merselling agent / carboxymethylating agent) is generally 0.99 to 2.45 when monochloroacetic acid or sodium monochloroacetic acid is used as the carboxymethylating agent. Will be adopted by. The reason is that if it is less than 0.90, the carboxymethylation reaction may be insufficient, and unreacted monochloroacetic acid or sodium monochloroacetate may remain, resulting in waste. If it exceeds 45, a side reaction between the excess marcel agent and monochloroacetic acid or sodium monochloroacetic acid may proceed to form an alkali metal glycolic acid salt, which may be uneconomical.

In carboxymethylation, the effective utilization rate of the carboxymethylating agent is preferably 15% or more. It is more preferably 20% or more, further preferably 25% or more, and particularly preferably 30% or more. The effective utilization rate of the carboxymethylating agent refers to the ratio of the carboxymethyl group introduced into cellulose among the carboxymethyl groups in the carboxymethylating agent. By using a solvent mainly containing water for marcel formation and using a mixed solvent of water and an organic solvent for carboxymethylation, a high effective utilization rate of the carboxymethylating agent (that is, a carboxymethylating agent) The carboxymethylated cellulose of the present invention can be obtained economically without significantly increasing the amount of the solvent used. The upper limit of the effective utilization rate of the carboxymethylating agent is not particularly limited, but in reality, the upper limit is about 80%. The effective utilization rate of the carboxymethylating agent may be abbreviated as AM.

The method for calculating the effective utilization rate of the carboxymethylating agent is as follows:
AM = (DS x number of moles of cellulose) / number of moles of carboxymethylating agent DS: degree of carboxymethyl substitution (measurement method will be described later)
Number of moles of cellulose: Pulp mass (dry mass when dried at 100 ° C. for 60 minutes) / 162
(162 is the molecular weight of cellulose per glucose unit).
The concentration of the cellulose raw material in the carboxymethylation reaction is not particularly limited, but is preferably 1 to 40% (w / v) from the viewpoint of increasing the effective utilization rate of the carboxymethylating agent.

At the same time as the addition of the carboxymethylating agent, or immediately before or after the addition of the carboxymethylating agent, an organic solvent or an aqueous solution of the organic solvent is appropriately added to the reactor, or water other than the water used for the marcelification treatment by reducing the pressure or the like. The organic solvent and the like of the above are appropriately reduced to form a mixed solvent of water and the organic solvent, and the carboxymethylation reaction is allowed to proceed under the mixed solvent of the water and the organic solvent. The timing of addition or reduction of the organic solvent may be between the end of the mercerization reaction and immediately after the addition of the carboxymethylating agent, and is not particularly limited, but for example, 30 minutes before and after the addition of the carboxymethylating agent. Within is preferable.

Examples of the organic solvent include alcohols such as methanol, ethanol, N-propyl alcohol, isopropyl alcohol, N-butanol, isobutanol and tertiary butanol, ketones such as acetone, diethyl ketone and methyl ethyl ketone, and dioxane and diethyl ether. Examples thereof include benzene and methanol, and these alone or a mixture of two or more thereof can be added to water and used as a solvent for carboxymethylation. Of these, monohydric alcohols having 1 to 4 carbon atoms are preferable, and monohydric alcohols having 1 to 3 carbon atoms are more preferable because of their excellent compatibility with water.

The ratio of the organic solvent in the mixed solvent at the time of carboxymethylation is preferably 20% by mass or more, more preferably 30% by mass or more, based on the total amount of water and the organic solvent. It is more preferably 40% by mass or more, further preferably 45% by mass or more, and particularly preferably 50% by mass or more. The higher the proportion of the organic solvent, the more likely it is that uniform substitution of carboxymethyl groups will occur, and the advantage of obtaining stable quality carboxymethylated cellulose can be obtained. The upper limit of the proportion of the organic solvent is not limited and may be, for example, 99% by mass or less. Considering the cost of the organic solvent to be added, it is preferably 90% by mass or less, more preferably 85% by mass or less, still more preferably 80% by mass or less, still more preferably 70% by mass or less.

The reaction medium for carboxymethylation (a mixed solvent of water and an organic solvent, etc., which does not contain cellulose) has a smaller proportion of water than the reaction medium for mercerization (in other words, the proportion of the organic solvent is higher). Many) is preferable. By satisfying this range, it becomes easy to maintain the crystallinity of the obtained carboxymethylated cellulose, and the carboxymethylated cellulose of the present invention can be obtained more efficiently. In addition, when the reaction medium for carboxymethylation has a smaller proportion of water (more proportion of organic solvent) than the reaction medium for mercerization, the transition from the mercerization reaction to the carboxymethylation reaction occurs. Another advantage is that a mixed solvent for the carboxymethylation reaction can be formed by a simple means of adding a desired amount of an organic solvent to the reaction system after the completion of the mercerization reaction.

After forming a mixed solvent of water and an organic solvent and adding a carboxymethylating agent to the mercerized cellulose, the temperature is preferably kept constant in the range of 10 to 40 ° C. for 15 minutes to 4 hours, preferably 15 Stir for about 1 minute to 1 hour. The mixing of the liquid containing mercerized cellulose and the carboxymethylating agent is preferably carried out in a plurality of times or by dropping in order to prevent the reaction mixture from becoming hot. After adding the carboxymethylating agent and stirring for a certain period of time, the temperature is raised if necessary, and the reaction temperature is set to 30 to 90 ° C., preferably 40 to 90 ° C., more preferably 60 to 80 ° C. for 30 minutes to The etherification (carboxymethylation) reaction is carried out for 10 hours, preferably 1 to 4 hours to obtain carboxymethylated cellulose. By raising the temperature during the carboxymethylation reaction, there is an advantage that the etherification reaction can be efficiently carried out in a short time.

At the time of carboxymethylation, the reactor used for mercerization may be used as it is, or another reactor capable of mixing and stirring each of the above components while controlling the temperature may be used. ..

After completion of the reaction, the remaining alkali metal salt may be neutralized with a mineral acid or an organic acid. Further, if necessary, the by-produced inorganic salts, organic acid salts and the like may be washed with hydrous methanol to remove them, and then dried, pulverized and classified to obtain carboxymethylated cellulose or a salt thereof. Examples of the device used for dry pulverization include impact mills such as hammer mills and pin mills, medium mills such as ball mills and tower mills, and jet mills. Examples of the apparatus used in the wet pulverization include apparatus such as a homogenizer, a mascoroider, and a pearl mill.

The reason why carboxymethylated cellulose capable of forming a dispersion having a low viscosity even though the degree of carboxymethyl substitution is 0.50 or less and the degree of crystallization of cellulose type I is 50% or more is obtained by the above production method, carboxy It is not clear why carboxymethylated cellulose having a small absolute value of anionization can be obtained even though the degree of methylation is 0.50 or less and the degree of crystallization of cellulose type I is 50% or more, but the present invention. They speculate: By performing the cellulolysis reaction using a water-based solvent, the cellulosic agent is more likely to be mixed uniformly, and the cellulolysis reaction occurs more uniformly. In addition, the presence of an organic solvent in carboxymethylation improves the effective utilization rate of the carboxymethylating agent, resulting in a side reaction by the surplus carboxymethylating agent (for example, formation of an alkali metal glycolic acid salt). Is less likely to occur and the quality is stabilized, so that the viscosity is lowered and the absolute value of the degree of anionization is considered to be small.

It is considered that such carboxymethylated cellulose has increased water retention because carboxymethylation occurs uniformly, while carboxymethylated cellulose is easily dispersed uniformly and is less likely to aggregate. However, it does not exclude theories other than these.

<Water treatment agent, filter material>
The carboxymethylated cellulose thus obtained is suitable for use in the water treatment agent of the present invention. As described above, the carboxymethylated cellulose used in the present invention has high water retention, excellent dispersibility, and is difficult to aggregate. Therefore, when used as a water treatment agent, it is excellent in water removal and easy to filter. It exerts an excellent effect. Further, when the water treatment agent of the present invention is used as a filter material, the water removal rate is excellent, and the flow rate of the filtrate is also excellent.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Unless otherwise specified, parts and% indicate parts by mass and% by mass.

(Manufacturing Example 1)
To a biaxial kneader whose rotation speed was adjusted to 100 rpm, 130 parts of water and 20 parts of sodium hydroxide dissolved in 100 parts of water were added, and hardwood pulp (LBKP manufactured by Nippon Paper Industries Co., Ltd.) was added at 100 ° C. 60. 100 parts were charged by the dry mass when dried for 1 minute. Mercerized cellulose was prepared by stirring and mixing at 30 ° C. for 90 minutes. Further, 100 parts of isopropanol (IPA) and 60 parts of sodium monochloroacetate were added with stirring, and after stirring for 30 minutes, the temperature was raised to 70 ° C. and a carboxymethylation reaction was carried out for 90 minutes. The concentration of IPA in the reaction medium during the carboxymethylation reaction is 30%. After completion of the reaction, the reaction was neutralized with acetic acid to a pH of about 7, deliquesed, dried, and pulverized to obtain a sodium salt of carboxymethyl cellulose having a carboxymethyl substitution degree of 0.24 and a cellulose type I crystallinity of 73%. Obtained. The effective utilization rate of the carboxymethylating agent was 29%. The method for measuring the degree of carboxymethyl substitution and the degree of crystallization of cellulose type I, and the method for calculating the effective utilization rate of the carboxymethylating agent are as described above.

The obtained sodium salt of carboxymethylated cellulose was dispersed in water to obtain a 1% (w / v) aqueous dispersion. About this, when the viscosity was measured by the above-mentioned method, it was 5.6 mPa · s.

The degree of anionization of the obtained sodium salt of carboxymethylated cellulose was measured by the above method and found to be 0.32 meq / g.

(Manufacturing Example 2)
A sodium salt of carboxymethylated cellulose was obtained in the same manner as in Example 1 except that the concentration of IPA in the reaction solution during the carboxymethylation reaction was set to 50% by changing the amount of IPA added. The degree of carboxymethyl substitution was 0.31, the degree of crystallinity of cellulose type I was 66%, and the effective utilization rate of the carboxymethylating agent was 37%. The obtained sodium salt of carboxymethylated cellulose was used as an aqueous dispersion having a solid content of 1% (w / v), and the viscosity was measured in the same manner as in Example 1 and found to be 5.6 mPa · s. The degree of anionization of the obtained sodium salt of carboxymethylated cellulose was measured in the same manner as in Example 1 and found to be 0.53 meq / g.

(Manufacturing Example 3)
A sodium salt of carboxymethylated cellulose was obtained in the same manner as in Example 1 except that the solvent used in the mercerization reaction was 10% water and 90% IPA, and the solvent having the same composition was also used in the carboxymethylation reaction. The degree of carboxymethyl substitution was 0.29, the degree of crystallinity of cellulose type I was 66%, and the effective utilization rate of the carboxymethylating agent was 35%. The obtained sodium salt of carboxymethylated cellulose was used as an aqueous dispersion having a solid content of 1% (w / v), and the viscosity was measured in the same manner as in Example 1 and found to be 35.5 mPa · s. The degree of anionization of the obtained sodium salt of carboxymethylated cellulose was measured in the same manner as in Example 1 and found to be 1.10 meq / g.

(Examples 1 and 2, Comparative Example 1)
The carboxymethylated cellulose obtained in Production Examples 1 to 3 was used as a water treatment agent (filter material) in Examples 1 and 2 and Comparative Example 1, and the following evaluation of water removal in oil was carried out.

<Evaluation of water removal in oil>
After setting a glass funnel (Kiriyama funnel) on a suction filter (manufactured by Leybold) and laying filter paper (5C standard) on the bottom surface so that the entire bottom surface is covered.
The carboxymethylated celluloses obtained in Production Examples 1 to 3 were spread evenly on the filter paper so as to be 2 g each.

After that, 10 ml of water and 40 ml of oil (manufactured by J-Oil Mills, product name: canola oil that finishes easily) are poured into the glass funnel without delay, suction filtration is started, suction is stopped after 60 minutes, and the filtrate is set according to the following criteria. Evaluated in.

(Passing amount of filtrate)
The total amount of the filtrate obtained by suction filtration was measured using a measuring cylinder.

(Amount of water and amount of oil in the filtrate)
For the amount of water and oil in the filtrate, the amount of liquid up to the interface with water / oil was measured using a measuring cylinder.

The water treatment agent of the present invention showed good passage of the filtrate. Moisture was selectively removed from the filtrate, showing excellent water treatment properties.

On the other hand, the water treatment agent used in the comparative example aggregated when it came into contact with water, did not pass through suction filtration, and could not obtain a filtrate.

Claims (6)

A water treatment agent containing carboxymethylated cellulose having a degree of carboxymethyl substitution of 0.50 or less and a degree of crystallinity of cellulose type I of 50% or more. The water treatment agent according to claim 1, wherein the carboxymethylated cellulose has a degree of anionization of 0.00 meq / g or more and 1.00 meq / g or less. Claim 1 is characterized in that the viscosity (30 rpm, 25 ° C.) of the carboxymethylated cellulose as an aqueous dispersion having a solid content of 1% (W / V) is 30.0 mPa · s or less. ~ 2 The water treatment agent according to any one of. The water treatment according to any one of claims 1 to 3, wherein the carboxymethylated cellulose has a structure in which a carboxymethyl group is ether-bonded to a part of hydroxyl groups in a glucose residue constituting the cellulose. Agent. A filter medium containing the water treatment agent according to any one of claims 1 to 4. A method for removing water in oil, which comprises the following steps (A) to (B).
Step (A): A step of bringing the water treatment agent according to any one of claims 1 to 4 into contact with an oily composition containing water.
Step (B): A step of filtering out the water treatment agent from the oily composition.