JP5586186B2 - A method for producing alkali cellulose or a derivative thereof. - Google Patents

Description

The present invention relates to a method for producing alkali cellulose using a minimum amount of water, and a method for producing a cellulose ether derivative from alkali cellulose obtained by homogeneously dispersing an alkali metal obtained by the method.

Alkali cellulose is important as a precursor of a cellulose derivative. It has been used as a raw material for cellulose ethers such as methyl cellulose, ethyl cellulose, and CMC (carboxymethyl cellulose), starting with a viscose raw material, and its manufacturing method has been developed for a long time.
Cellulose is a linear polymer in which glucose is linked by β-1,4. Cellulose has many hydroxyl groups, and in addition to hydrogen bonding within the molecule, hydrogen bonds are formed between the molecules, and the cellulose has a chemically strong structure. From the viewpoint of crystal structure, it is well known that cellulose has a heterogeneous structure consisting of a crystal part in which the polymer constituting it is focused and a non-crystal part that is loosely arranged. .
Introducing alkali into cellulose to make it into alkali cellulose has various problems due to the existence of such a very strong structure in terms of chemical and crystallography and the presence of a heterogeneous structure. It is letting me. That is, the degree of alkali substitution in alkali cellulose and the uniform dispersibility of alkali substituents have a considerable influence on the properties of various cellulose ether derivatives derived therefrom. For example, the swellability or solubility of carboxymethyl cellulose, which is a kind of cellulose ether derivative, in water is greatly influenced by the degree of alkali substitution of alkali cellulose as a raw material.

Conventionally, generally, in the production of alkali cellulose, a chemical reaction using a high concentration (usually 10 to 20% by weight or 20 to 45% by weight) of NaOH solution in a large excess with respect to solid cellulose. I was letting.
When some prior arts are extracted from patent documents, there are the following documents.

JP-A-9-316101 International Publication WO 01/346552 JP 2001-302701 A JP 2006-348177 A JP 2007-197678 A JP 2007-197679 A JP 2007-197680 A

The following is a summary of these documents in terms of the ratio of water used in the production of alkali cellulose and the mechanical treatment.
In Patent Document 1, for example, in a working example, a solution having a cellulose concentration of 5 to 8% is processed using a high-speed stirring mixer (TK homomixer).
In Patent Document 2, the cellulose content is 4 to 12% by weight, and means such as media-type wet pulverization, a low-temperature stirring kneader (kneader), and a homomixer are used.
In Patent Document 3, for example, in Example 1, 6.7 g of water is used for 10 g of pulp and is processed by a biaxial kneader.
In Patent Document 4, for example, a high-speed dispersion device (specifically, a flow jet mixer) is used at a ratio of 44 kg of water to 35 kg of pulp.
In Patent Document 5, for example, in Example 1, 49 kg NaOH aqueous solution 1700 (l) is used for 50 kg of pulp and processed by a screw conveyor.
In Patent Document 6, for example, in Examples 4 and 5, a 44% NaOH aqueous solution 150 (l) is used for 15 kg of pulp and is processed by a rotary feeder.
In Patent Document 7, for example, in Example 1, 49 kg NaOH aqueous solution 1300 (l) is used for 50 kg of pulp, and processed with a pipe-type contactor.

  As described above, in Patent Documents 1 to 7, the amount of water used is the minimum amount as in the present invention (the proportion of water with respect to the amount of pulp + water is 10 to 30%, conversely, the proportion of pulp. Is 90-70%), but far from it. In addition, the machines used for the alkalinization process are only apparatuses mainly intended for kneading and dispersion, and the “high shear” is used to loosen the strong crystal structure of cellulose as in the ball mill of the present invention and to break up the cellulose molecular chains. Nothing like “mechanical processing that can be applied and mixed” is described. As described above, if a large amount of NaOH or water is used, it may be possible to alkalinize the cellulose into alkali cellulose. However, (1) the apparatus for the alkalizing operation becomes large-scale, (2 ) There were problems such as a large amount of waste liquid being discharged. In addition, (3) solid cellulose has a crystal part and an amorphous part, and the progress of alkalinization of the part of the crystal structure is delayed, which hinders the progress of uniform and rapid chemical reaction. This also has the problem that (4) only alkali cellulose that is not sufficiently alkalized (that is, cellulose that retains the original crystal structure of cellulose, cellulose with a low degree of substitution) has been produced. It was happening.

  Therefore, the present invention aims to solve the conventional problem that a large amount of high-concentration NaOH aqueous solution is used in the production of alkali cellulose, the operation / device becomes large-scale, and a large amount of waste liquid is produced. To do. Another object of the present invention is to efficiently produce alkali cellulose having a highly uniform dispersibility of alkali substituents. It is another object of the present invention to produce an ether derivative having a high etherification rate derived from alkali cellulose.

  Therefore, as a result of searching for a method for solving the above problems of the prior art and repeated trial and error, water is a minimum amount (water is 10 to 30% by weight with respect to the total amount of water and solid cellulose). In addition, it was discovered that by performing mechanical treatment, it was possible to produce alkali cellulose in which alkali substitution was effectively carried out and the substituents were uniformly dispersed, and the present invention was completed based on that. It came to do.

The present invention relates to the method for producing alkali cellulose described in the following (1) to ( 3 ) and the method for producing the cellulose ether derivative described in ( 4 ) to ( 6 ).
(1) In producing alkali cellulose by subjecting cellulose to mechanical treatment in the presence of water and alkali, the amount of water is 10 to 30% by weight based on the total of water and cellulose. Use, mechanical treatment, first add water to the mechanical treatment, then add alkali hydroxide to mechanical treatment to loosen the cellulose crystal structure, cellulose molecular chain In which water and alkali hydroxide are infiltrated into cellulose, and the mechanical treatment is performed by a ball mill, rod mill, hammer mill, disc mill, extruder, biaxial kneader or Banbury mixer , A method for producing alkali cellulose.
(2) The alkali cellulose according to (1), wherein the alkali is used in an amount of 50 to 11% (the denominator is cellulose + alkali) with respect to the total amount of cellulose. Manufacturing method.
(3) The alkali cellulose according to (1) or (2), wherein the alkali is used in such a ratio as to form an aqueous solution having a concentration of 90 to 10% by weight (the denominator is alkali + water) with respect to water. Manufacturing method.
( 4 ) Alkyl halide, alkylene oxide, halogenated acetic acid, or vinyl as an etherifying agent for alkali cellulose obtained in the production process of alkali cellulose comprising the production method according to any one of (1) to ( 3 ) The manufacturing method of the cellulose ether derivative characterized by having the manufacturing process of the ether derivative which makes a system monomer react.
( 5 ) In the manufacturing process of an ether derivative, when the etherifying agent is solid, a solvent capable of dissolving the etherifying agent is used. ( 4 ) The method for manufacturing a cellulose ether derivative according to ( 4 ).
( 6 ) The method for producing a cellulose ether derivative according to ( 5 ), wherein carboxymethylcellulose is produced as an ether derivative using monochloroacetic acid as an etherifying agent in the production step of the ether derivative.

According to the present invention, when producing alkali cellulose, a large amount of high-concentration NaOH aqueous solution is used, the operation / device becomes large-scale, and a conventional problem that a large amount of waste liquid comes out can be solved.
By adopting a technical configuration in which the present invention is subjected to a mechanical treatment in the presence of extremely small water, alkali cellulose can be efficiently produced, and an alkali substituent having high uniform dispersibility can be obtained. In addition to having an effect as a production method that can be obtained, the alkali cellulose that is the product is also a novel one that has not been heretofore in terms of high uniform dispersion of alkali substituents, and The ether derivative derived therefrom has an effect that a compound having a high etherification rate and few side reactions can be obtained.

It is a model figure which shows typically the role which a mechanical process plays when alkalizing a cellulose under water content. It is drawing which shows the wide angle X-ray-diffraction intensity | strength of the alkali cellulose obtained by Example 1 (Na0H3mol, water washing after a ball mill process). It is a NMR figure of the alkali cellulose obtained in Example 1 (Na0H3 mol). It is drawing which shows the wide-angle X-ray-diffraction intensity | strength of the alkali cellulose obtained by Example 2 (Na0H1mol, water washing after a ball mill process). It is a NMR figure of the alkali cellulose obtained in Example 2 (Na0H1 mol). It is the raw data of the infrared-spectroscopy spectrum of No. 13-15 of Table 1 which is an etherified substance (ether derivative) which etherified alkali cellulose with monochloro acetic acid. It is the raw data of the infrared spectroscopy spectrum of No.16-18 of Table 1 which is an etherified substance (ether derivative) which etherified alkali cellulose with monochloro acetic acid.

  In the method of producing alkali cellulose by reacting cellulose with alkali, which is performed while subjecting to mechanical treatment in the presence of very small water, the following tendency has been found as a result of research. is there.

(A) About composition and uniformity of alkali cellulose In its production process (alkali cellulose production process),
(1) The larger the ratio of NaOH to water in which the reaction form exists (that is, NaOH> H ₂ O), the higher the reaction rate and the greater the degree of substitution.
(2) The greater the ratio of cellulose to water (ie, the greater the cellulose> H ₂ O, the less water, the greater the uniformity of the alkali cellulose produced),
It turns out.
(B) Side reaction of the etherifying agent when etherifying alkali cellulose When the produced alkali cellulose is reacted with an etherifying agent (eg, halogenated acetic acid) to produce a cellulose ether derivative (eg, carboxymethyl cellulose) ( In the production process of ether derivatives)
(3) In the production process of alkali cellulose (alkali cellulose production process), the greater the ratio of NaOH to water present in the reaction system (that is, NaOH> H ₂ O), the better the ether production.
(4) In the production process of alkali cellulose (alkali cellulose production process), the greater the ratio of water to NaOH (that is, the more H ₂ O> NaOH, the more water is present), the easier it is to produce alcohol. ,
(5) In the production process of alkali cellulose (alkali cellulose production process), the greater the ratio of cellulose to water (that is, the greater the cellulose> H ₂ O, vice versa), Reaction is suppressed,
I understood that.

From the above knowledge, when producing alkali cellulose from cellulose, the less water is present (in other words, the lower the moisture content of cellulose) is, not only the production of alkali cellulose but also the cellulose derived therefrom It turns out that it is good also in ether manufacture.
However, the presence of a small amount of water is indispensable for the reaction, and the role of water is (i) acting as a carrier for NaOH and (ii) acting as an alkali cellulose swelling agent. Can penetrate).

Also, the role of mechanical treatment is to impart shearing force, preferably high shearing force, to the hard cellulose, loosen the strong crystal structure of the cellulose, make the cellulose molecular chains fall apart, and water / alkaline solution to the cellulose It facilitates penetration.
FIG. 1 schematically illustrates this.
In the chemical reaction, the mechanical treatment is simultaneously performed in parallel with the strong crystal structure that prevents the chemical reaction, thereby increasing the chance of contact between the cellulose molecules and the aqueous alkali solution. As a result, the uniform reaction product, that is, alkali substitution A group having a high uniform dispersibility can be obtained.
Since the conventional product was not subjected to such mechanical treatment, a strong crystal structure of cellulose partially remained, and a product having high uniform dispersibility of alkali substituents was not obtained. Therefore, it can be said that the alkali cellulose of the present invention is novel from the viewpoint of a substance.

[cellulose]
As the cellulose used in the present invention, any cellulose present in natural plants can be used, and wood, paper, pulp, cotton, bacterial cellulose, etc. can be used. It is desirable to contain. For example, used sheets (100% cotton), towels, table cloths, yukata, shirts and other textiles are preferable.

[alkali]
Alkali metal hydroxides, lithium, sodium, potassium, rubidium, cesium hydroxides and carbonates can be used. Among these, sodium hydroxide, potassium hydroxide, and sodium carbonate are preferable because they can be easily obtained.

[Water content: amount of water used for alkalinizing cellulose]
In the production of alkali cellulose, water is used in such an amount that the ratio is 10 to 30% by weight with respect to the total of water and cellulose. However, when the amount is less than 10%, the alkali is not diffused into the cellulose solid. When it exceeds 50%, excessive water is liberated, resulting in inconvenience that a large apparatus is required due to dissipation of external force and increase in the total volume.
The proportion of water used is more preferably 10 to 30% by weight, and more preferably 15 to 25% by weight in consideration of the role as a water medium and the reaction efficiency.

[Amount of alkali used]
Although the usage-amount with respect to the cellulose of an alkali changes with alkali substitution degree of the target alkali cellulose, it is 0.5-4 mol per glucose unit of a cellulose. 0.5 mol is the lower limit for obtaining a water-soluble cellulose ether derivative, while at 4 mol or more, the alkali becomes excessive, resulting in a large amount of waste liquid, resulting in production cost disadvantages, It lacks consideration.
The upper limit and the lower limit of the ratio of alkali to water are 90 to 10 (the denominator is alkali + water), although the upper limit and the lower limit are regulated from the ratio of water to cellulose and the ratio of alkali to cellulose.

[Mechanical processing and equipment]
The mechanical treatment of the present invention may be any as long as it can perform a treatment that generates a shearing force that loosens the crystal structure of cellulose and breaks it apart. More suitable is a “mechanical process in which a high shear force is applied and mixed”. As an apparatus used for it, what kind of thing may be sufficient if a physical external force can be applied to a cellulose and a grinder (grinder) is also included.
Of course, the equipment used to break up and crush the fibers containing natural cellulose can also be used.
However, since the mechanical treatment is performed in the presence of water or alkali, it is needless to say that it must have a sealed structure so that they do not escape. Examples of such an apparatus capable of performing mechanical processing include a ball mill, a biaxial kneader, a rod mill, a hammer mill, a disc mill, an extruder (biaxial kneader), and a Banbury mixer.
When using a ball mill as an apparatus for performing mechanical treatment, it can be carried out at a rotation speed of 100 rpm to 300 rpm for 10 to 180 minutes with an appropriate interruption time.

[Etherizing agent]
Etherifying agents include alkyl halides such as methyl chloride, ethyl chloride, propyl chloride, and butyl chloride, alkylene oxides such as ethylene oxide and propylene oxide, vinyl alcohol, vinyl acetate, acrylonitrile, acrylamide, vinyl monomers, and halogenated carboxyls. Examples include acids such as monochloroacetic acid.

[Cellulose ether obtained from alkali cellulose]
Cellulose ethers obtained using alkali cellulose as a starting material include methyl cellulose, ethyl cellulose (EC), propyl cellulose, butyl cellulose, hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), and hydroxyethyl methyl cellulose which is a mixed cellulose ether thereof. (HEMC), hydroxypropylmethylcellulose (HPMC), carboxymethylcellulose (CMC), carboxyethylcellulose, carbamoylethylcellulose.

Details of the present invention will be described in the examples. The present invention is not limited to these examples.
The present invention and comparative examples are shown below.

In Example 1, (1-2) and (1-3) are examples of the present invention, and (1-1) and (1-4) are comparative examples.
[Production of alkali cellulose]
Used sheets (100% cotton) are used as the raw material cellulose. As the alkali, NaOH particles manufactured by Nacalai Tesque are used.
Water is not added to 10g of used sheets, 1.1g of water, 2.5g of water and 10g of water are added respectively, and water is 0%, 10%, 20%, respectively, for the total amount of used sheets and water. 50% (water content, 0%, 10%, 20%, 50%). It was put into a planetary ball mill apparatus (manufactured by Fritsch Co., Ltd., special container and balls made of zirconia), and subjected to a ball mill treatment at 300 rpm for 30 minutes.
Next, 7.4 g of NaOH particles (3 mol per 1 mol of cellulose) were added, and the ball mill treatment was performed again by operating for 10 minutes at 300 rpm for 10 minutes and repeating the pause for 10 minutes to achieve a total operation time of 30 minutes. .

[X-ray diffraction]
The obtained product was washed with water, and then the wide-angle X-ray diffraction intensity was measured. The results are as shown in FIG.
In (1-3) having a water content of 20%, peaks derived from Cellulose II (hydrated cellulose regenerated from alkali cellulose) appear most clearly at 2θ = 12.1, 19.8, and 22.0 °. Thus, the fact that the peak derived from Cellulose II is clearly observed indicates that the alkali cellulose conversion is proceeding effectively by the above ball mill treatment.
In (1-1) with a water content of 0%, (1-2) with a water content of 10%, and (1-4) with a water content of 50%, Cellulose I at 2θ = 14.7, 16.5, 22.6 ° The peak derived from (natural cellulose) remained, indicating that it was unreacted. However, since (1-2) with a moisture content of 10% changes slightly compared with (1-1) with a moisture content of 0%, it is considered that Cellulose II is generated even slightly. is there.

[NMR]
23Na-NMR analysis was performed on the product obtained in the above [Production of alkali cellulose], that is, the product obtained after ball mill treatment with 3 mol of NaOH. FIG. 3 shows the result. The horizontal axis of FIG. 3 represents a difference in ppm when sodium of sodium chloride is used as a reference. It represents that Na has couple | bonded with the hydroxyl group of a cellulose, so that the position of a peak is a minus side and the width of a peak is broad.
(1-2) having a water content of 10% and (1-3) having a water content of 20% are the other two factors in which sodium is bound to cellulose, that is, (1-1) having a water content of 0% and water content. It is higher than (1-4), where the rate is 50%.
(1-1) having a moisture content of 0% has a peak at +10.2387 ppm, whereas (1-2) and (1-3) having a moisture content of 10% and 20% (of the present invention) are -5. There are peaks at 6806 and -5.5829, which reflect the difference in chemical structure between cellulose and sodium cellulose, the difference between OH and -ONa. Further, (1-4) having a moisture content of 50% has a peak at +0.7649, which is close to that of the present invention as compared to (1-1) having a moisture content of 0%, but indicates that the degree of alkali substitution is low. Is. This is because it is considered to react with water, not cellulose.
In the crystal structure analysis by wide-angle X-ray diffraction, Cellulose II, which indicates the formation of alkali cellulose, was not clearly shown at a water content of 10% (1-2), but the formation of alkali cellulose was clearly recognized by NMR analysis. It is.

In Example 2, (3-2) and (3-3) are examples, and (3-1) and (3-4) are comparative examples.
[Production of alkali cellulose]
In Example 2, “7.4 g of NaOH particles (3 mol per 1 mol of cellulose) were added” in “Production of alkali cellulose” of Example 1 was compared with Example 1, but “2.5 g of NaOH was added. It is different in that it is “adding grains (1 mol per 1 mol of cellulose)”, and the other points are the same as in Example 1.

[X-ray diffraction]
The obtained product was washed with water, and then the wide-angle X-ray diffraction intensity was measured. The results are as shown in FIG.
In (3-3) having a water content of 20%, 2θ = 12.1, 19.8, and 22.0 ° are peaks derived from Cellulose II (hydrated cellulose regenerated from alkali cellulose). This sample is considered to have undergone the most alkali cellulose conversion by the above ball mill treatment.
In (3-1) with a water content of 0%, (3-2) with a water content of 10%, and (3-4) with a water content of 50%, Cellulose I at 2θ = 14.7, 16.5, 22.6 ° The peak derived from (natural cellulose) remained considerably, indicating that it was unreacted.
However, compared to (3-1) with a moisture content of 10%, the peak shape changes slightly compared to (3-1) with a moisture content of 0%, indicating that Cellulose II is produced even in a slight amount. is there.
In addition, the sharp peak seen near 28 ° is due to the internal standard substance Si.

[NMR]
23Na-NMR analysis was performed on the product obtained in the above [Production of alkali cellulose], that is, the product after ball mill treatment with 1 mol of NaOH. FIG. 5 shows the result. The horizontal axis of FIG. 5 represents the difference in ppm when sodium chloride is used as a reference. It represents that Na has couple | bonded with the hydroxyl group of a cellulose, so that the position of a peak is a minus side and the width of a peak is broad.
The water content of (3-2) with a water content of 10% and (3-3) with a water content of 20% are the other two, ie, (3-1) with a water content of 0% and the water content of sodium. It is higher than (3-4), where the rate is 50%.
(3-1) having a moisture content of 0% has a peak at +9.9443 ppm, whereas (3-2) and (3-3) having a moisture content of 10% and 20% (of the present invention) are -7. There are peaks at 9273 and -1.7747, which reflect the difference in chemical structure between cellulose and sodium cellulose, and the difference between OH and -ONa. Further, (3-4) having a water content of 50% has a peak at +0.8625, which is close to that of the present invention as compared to (3-1) having a water content of 0%, but indicates that the degree of alkali substitution is low. Is.
In the crystal structure analysis by wide-angle X-ray diffraction, Cellulose II, which indicates the formation of alkali cellulose, was not clearly observed at a water content of 10% (3-2), but the formation of alkali cellulose was clearly observed by NMR analysis. It is.

In Example 3, using a ball mill, carboxymethylcellulose conversion was examined for a sheet of 100% cotton.
[Production of alkali cellulose]
Used sheets (100% cotton) are used as the raw material cellulose. As the alkali, NaOH particles manufactured by Nacalai Tesque are used.
To 10 g of used sheets, 2.5 g of water was added so that the water was 20% (water content, 20%) with respect to the total amount of used sheets and water. It was put into a planetary ball mill apparatus (manufactured by Fritsch Co., Ltd., special container and balls made of zirconia), and subjected to a ball mill treatment at 300 rpm for 30 minutes. Next, 7.4 g of NaOH particles (3 mol per 1 mol of cellulose) were added, and ball mill treatment was performed again at 300 rpm for 30 minutes, 10 minutes of operation, and 10 minutes of pausing until the total operation time was 30 minutes. It was.

[Production of carboxymethyl cellulose]
To this was added a solution obtained by dissolving monochloroacetic acid (ClCH ₂ COOH) in isopropanol (IPA), placed in a ball mill, and mechanically treated at a rotation speed of 150 (rpm). Table 1 shows the amounts of IPA and monochloroacetic acid, ball mill treatment conditions, and IR (infrared spectroscopic analysis) results of the produced carboxymethyl cellulose.

In Table 1, the meaning of (1600 + 1730) / 3500 is as follows.
3500 (cm ⁻¹ ) is absorption by a hydroxyl group, that is, a hydroxyl group of cellulose, and corresponds to an unreacted portion. 1600 (cm ⁻¹ ) and 1730 (cm ⁻¹ ) are absorptions derived from carboxyl groups and correspond to the portion where the reaction has proceeded. Therefore, (1600 + 1730) / 3500 represents a reaction part / an unreacted part, and simply indicates the degree to which the hydroxyl group of cellulose has been replaced by a carboxymethyl group, that is, the degree of progress of carboxymethylation.

  6 and 7 show the experiment No. in Table 1. 13-15, no. 16 to 18 IR (infrared spectroscopy) raw data.

  According to the present invention, not only can an alkali cellulose be efficiently produced from cellulose, but the obtained alkali cellulose has a uniform degree of alkali substitution, and the cellulose ether produced therefrom has a uniform etherification. Therefore, the production method and product are useful and highly industrially applicable.

Claims (6)

When producing alkali cellulose by mechanically treating cellulose in the presence of water and alkali, water should be used in such an amount that the ratio of water to cellulose is 10 to 30% by weight. First, mechanical treatment is performed by adding water to cellulose, followed by mechanical treatment by adding alkali hydroxide to loosen the crystal structure of the cellulose, and the molecular chains of the cellulose are separated. Impregnating water and alkali hydroxide into cellulose , the mechanical treatment being performed by a ball mill, rod mill, hammer mill, disk mill, extruder, twin screw kneader or Banbury mixer , Production method.   2. The method for producing alkali cellulose according to claim 1, wherein the alkali is used in an amount of 50 to 11% (the denominator is cellulose + alkali) with respect to the total of cellulose. .   3. The method for producing alkali cellulose according to claim 1, wherein the alkali is used in such a ratio as to form an aqueous solution having a concentration of 90 to 10% by weight with respect to water (the denominator is alkali + water). As etherifying agent in the alkali cellulose obtained in manufacturing process of the alkali cellulose consisting process according to any one of claims 1 to 3, is reacted alkyl halides, alkylene oxides, halogenated acetic acid, or a vinyl monomer The manufacturing method of the cellulose ether derivative characterized by having the manufacturing process of an ether derivative. In the manufacturing process of the ether derivatives, if the etherification agent is a solid, method for producing a cellulose ether derivative according to claim 4, characterized in that a solvent capable of dissolving it. 6. The method for producing a cellulose ether derivative according to claim 5 , wherein in the step of producing the ether derivative, carboxymethyl cellulose is produced as an ether derivative using monochloroacetic acid as an etherifying agent.