JP3533713B2 - Method for producing water-absorbing cellulose material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to a highly water-absorbing cellulose material.
The production method of the feed, especially the ability to absorb salt water
A method for producing a water-absorbing cellulose material having excellent gel strength
To do. The water-absorbing material obtained in the present invention has a large amount
Not only absorb water, but also
High water absorption capacity even for aqueous solutions containing
Therefore, various sanitary materials, agricultural materials, food packaging materials
Useful in a wide range of fields such as materials, civil engineering and building materials
It is. [0002] 2. Description of the Related Art Water or water containing salts such as salt water
In recent years, as a water-absorbing material for solutions, it has been called a highly water-absorbing resin.
A group of materials are known and have been put to practical use. these
Resin material basically cross-links water-soluble polymer slightly
Having a chemical structure insoluble in water
You. Such superabsorbent materials include, for example, starches.
After graft polymerization of acrylonitrile, this is hydrolyzed
Grafted with acrylic acid metal salt onto starch
, Acrylic acid polymerized with a copolymerizable crosslinking agent
Addition of bridge resin, methyl methacrylate-vinyl acetate copolymer
Numerous things such as hydrolysates have been proposed.
Some are in practical use. [0003] Known as a traditional water-absorbing material
Cotton, pulp, paper, cloth, sponge, etc. are subject to capillary action.
Water absorption, but in contrast to the above high water absorption
Because the principle of water absorption is osmotic pressure, resin
Even can absorb much more water. In addition, high absorption
The water-based resin easily regenerates water even if pressure is applied while absorbing water.
It has the excellent feature of not releasing. Because of this
Disposable disposable diapers, sanitary products
Such as sanitary materials, soil water retention, seedling raising sheets, etc.
Agricultural materials, food freshness preserving materials, dewatering materials, etc.
Prevention of mud lost when excavating fields and tunnels, dew condensation prevention sheet for buildings
Widely used as civil engineering and building materials. [0004] However, these superabsorbent resins are used in saline and
When used on solutions containing salts, such as urine,
Since the osmotic pressure, which is the driving force, decreases, the water absorption
And at the same time, the mechanical strength of the gel
Have a point. However, the above high water-absorbent resin
In application fields, it is sometimes necessary to use solutions containing salts.
Development of materials that exhibit high water absorption even in the presence of salt
Is desired. Sanita for disposable diapers, sanitary products, etc.
In the field of leek, the ability to absorb salt water under pressure is required
Therefore, improvement in gel strength is also required. [0005] The above-mentioned disadvantages of the conventional superabsorbent resin are solved.
Synthetic polymers such as sodium polyacrylate
Unlike in salt water, molecules do not become thread-like, unlike
Use polysaccharides that can maintain a broad conformation
Has been attempted. For example, polysaccharides are hydrophilic
Nomer graft polymerization method (JP-A-56-7641)
No. 9, JP-A-56-76481), polysaccharides and the like.
(JP-A-56-5137,
JP-A-58-79006, JP-A-60-5844
No. 3) is known. Cell as a polysaccharide
Loose derivatives (particularly using carboxymethylcellulose
Using the method described in JP-A-49-12898.
7, JP-A-50-85689, JP-A-54-85689
-163981, JP-A-56-28755
Report, JP-A-58-1701, JP-A-60-944
No. 01, JP-A-61-89364 and JP-A-5-89364
No. 80482) has also been studied. However
In any case, the disadvantages of the superabsorbent resin are sufficient.
It is hard to say that it has improved. On the other hand, the present inventors have proposed a cell insolubilized with water.
Loose derivative in a mixture of water and an organic solvent,
Swell to a degree of swelling of 3 to 30 g / g.
A gel of the lulose derivative is formed, separated from the solvent and
Water by replacing the water in the water with an organic solvent compatible with water.
Leaving and drying, the carbon number of the organic solvent and
Absorption of salt water by maintaining the content in a specific range
Proposal of manufacturing method for super absorbent cellulose material with excellent ability
(JP-A-6-172401). But
According to this method, the cellulose material with excellent salt water absorption
However, this material has poor gel strength and may lose its shape.
Because it is rubbed, it is a sanitary material such as disposable diapers and sanitary products
There is a disadvantage that it cannot be used. [0007] SUMMARY OF THE INVENTION
In order to solve the drawbacks of the prior art, the water absorption capacity of salt solution
Manufacture of cellulosic material with excellent properties of both force and gel strength
As a result of intensive studies on the fabrication method,
Cellulose which is solubilized and all carboxyl groups are acid type
In water, the carboxyl group of the acid type is
By partially neutralizing with alkali to form a salt form
Swelling in a specific range, uniform and continuous
The cellulose derivative can be swelled successively,
It has excellent properties of both water absorption capacity and gel strength
The present inventors have found that a cellulose derivative can be obtained, and have completed the present invention.
It has led to. An object of the present invention is to provide an aqueous solution containing various salts.
Cellulo with high water absorption and excellent gel strength
A water-absorbing cellulosic material comprising a cellulose derivative easily and
Another object of the present invention is to provide a low-cost manufacturing method. [0009] SUMMARY OF THE INVENTION The present invention provides
Water-insoluble and all carboxyl groups are acid type cells
After dispersing the loin derivative in an aqueous medium, the alkali is removed.
To neutralize the carboxyl groups to give a swelling degree of 3 to 30 g /
g of the cellulose derivative gel, and then the gel is
Separated from water and placed in an organic solvent compatible with water,
Acid type carboxy remaining in the gel by adding alkali
The group was returned to the salt form, and the gel was separated from the solvent.
Then, the water in the gel is replaced with the organic solvent and removed.
Salt water absorption capacity and gel strength characterized by drying and drying
This is a method for producing a water-absorbing cellulose material excellent in degree. [0010] The water insolubilized by the crosslinking used in the present invention.
Cellulose with all carboxyl groups in acid form
Carboxymethylcellulose, carboxy
Cimethyl hydroxyethyl cellulose, carboxyethyl
Water-soluble cellulose with carboxyl group such as cellulose
Raw material as a raw material,
One or more are used to provide cross-linking and
In some cases, all the radicals are in the acid form. This water-soluble cell
There is no particular limitation on the method of crosslinking the loin derivative,
The method of cross-linking by heating (thermal cross-linking)
A method in which a crosslinking agent is chemically reacted can be used. The crosslinking agent used in this case is formaldehyde
Aldehydes such as hide and glyoxal; dimethylo
Lurea, dimethylolethylene urea, dimethylol
N-methylol compounds such as imidazolidone; oxalic acid,
Polyvalent compounds such as maleic acid, succinic acid and polyacrylic acid
Bonic acids; ethylene glycol diglycidyl ether,
Polyethylene glycol diglycidyl ether, and
Polyepoxy compounds such as diepoxybutane; divinyl
Divinyl such as sulfone and methylenebisacrylamide
Compounds; dichloroacetone, dichloropropanol
And polyvalent halogen compounds such as dichloroacetic acid;
Halohi such as epichlorohydrin and epibromohydrin
Dolin compounds; and polyvalent aziridine compounds
Can be used. In addition, the crosslinking used in the method of the present invention
More water-insoluble and all carboxyl groups are in acid form
Another method for producing a cellulose derivative
Or graft a specific monomer onto a cellulose derivative
Copolymerization and, if necessary, hydrolysis and
Cross-linking, and all carboxyl groups are converted to acid form
May be used. Derivation of raw cellulose in this case
In addition to the above water-soluble cellulose derivatives, methyl
Cellulose, ethyl cellulose, hydroxyethyl cell
Loin, hydroxypropyl cellulose, cyanoethyl
Non-electrolyte cells such as cellulose and acetyl cellulose
Loose derivatives can also be used. [0013] The monomer used for the graft copolymerization and
Acrylic acid, methacrylic acid and their alkalis
A monomer having a carboxyl group, such as a metal salt,
Acrylamide, methacrylamide, acrylonitrile
, Methyl acrylate, ethyl acrylate, methacryl
For hydrolysis such as methyl acrylate and ethyl methacrylate
Therefore, a monomer containing a group that generates a carboxyl group is used.
it can. The crosslinking treatment may be performed before or after the graft polymerization.
Alternatively, an electrolyte-based water-soluble cellulose
Crosslinking may be carried out in the same manner as for conductors, or
Dimerizable with the monomer during the graft copolymerization process
Vinyl compounds such as N, N-methylenebisacrylia
Mid, N, N'-methylenebismethacrylamide, d
Graph in the presence of Tylene glycol diacrylate
Copolymerization may be performed. Cellulose derivatives as exemplified raw materials
Generally has an alkali metal ion at the carboxyl group
Manufactured in the combined salt form. In the present invention, first,
Remove carboxyl groups by removing alkali metal ions
To achieve this, the raw material must be added to an aqueous solution of a strong acid.
A method of keeping the pH below 1 by immersing the lulose derivative
The easiest. The carboxyl group of the cellulose derivative is converted to an acid form.
The strong acid used to reduce the pH to 1 or less
Any acid that can be lowered, such as hydrochloric acid, nitric acid, bromic acid, iodine
Inorganic compounds such as acid, sulfuric acid, perchloric acid and phosphoric acid, Aspa
Laginic acid, citric acid, glutamic acid, oxalic acid, salicy
Organics such as luic, malonic, phosphinic, and phosphonic acids
Compounds are exemplified. However, manufacturing costs and costs
Considering ease of handling, hydrochloric acid or sulfuric acid is the most suitable.
You. The acid concentration of the strong acid aqueous solution depends on the type of acid or cellulose derivative.
It depends on the type, but is 0.5 to 4 rules. Low concentration
If it is too high, it will not be completely in acid form.
Hydrolysis of the base derivative itself or removal of excess acid
It is not preferable because it becomes difficult. The amount of the strong acid aqueous solution depends on the type and concentration of the acid.
The pH of the solution during processing is always 1 or more.
Must be kept below, 1 kg of absolutely dry cellulose derivative
It may be added in an amount of 10 to 150 kg. Low addition amount
And not completely acid form, and too much acid will increase the amount of acid used
This is not preferred. The time of immersion in a strong acid aqueous solution
It depends on the concentration and the type of cellulose derivative.
Minutes to 2 hours. This time depends on the power of the cellulose derivative.
The time required for all the ruboxyl groups to be in the acid form
Highly water-absorbing cellulose that can be obtained for a longer time
The gel strength of the derivative tends to be improved. In addition, this anti
In consideration of the case where a volatile strong acid is used, 5 to 30
It is preferably performed at room temperature of ° C. Processed in the above way
Raw cellulose derivatives are acidified by filtration, centrifugal dehydration, etc.
Extra acid separated from the aqueous solution and then washed with water
Cell whose carboxyl groups are all acid type
A roast derivative can be obtained. Next, the acid-type cell thus obtained is obtained.
Disperse the lulose derivative in water and add alkali,
The degree of swelling of the cellulose derivative is 3 to 30 g / g.
To convert some of the carboxyl groups in the acid form into salt forms.
Then, the cellulose derivative is swollen to form a gel. here
The "swelling degree" is the weight of water held by the material to be swollen.
Then, specifically, it is measured by the method described later.
The degree of swelling is determined by various factors, the main one being
This is the ratio of conversion of the acid type carboxyl group to the salt type.
Crosslinked cellulose derivatives have all carboxyl groups
In the case of the acid form, it does not swell in water.
As the degree of swelling increases, the degree of swelling changes according to the converted ratio. Previous
From the acid form of the carboxyl group to the salt form to obtain the degree of swelling
Conversion ratio depends on the type of cellulose derivative and crosslink density.
Therefore, although different, 20-70% of all carboxyl groups
Range. By appropriately adjusting the above-mentioned factors,
Thus, the cellulose derivative is converted into a gel having the above-mentioned degree of swelling.
Can be If the degree of swelling is less than 3 g / g, water absorption and
Cannot achieve the desired performance in
When the moisture content is more than 30g / g, the gel becomes too soft
To separate the gel from the aqueous medium by filtration, centrifugal dehydration, etc.
It is not suitable because it becomes difficult to do. Cellulose having acid-type carboxyl group
Alkaline used for neutralization by adding to derivatives
Sodium hydroxide, lithium hydroxide, potassium hydroxide
, Rubidium hydroxide, cesium hydroxide, etc.
However, sodium hydroxide is preferred. Acid form
Disperse a cellulose derivative having a carboxyl group of
The amount of water to be added depends on the type of
It should be changed depending on the bridge density, but the dry cell
In the range of 50-100 kg per kg of the loin derivative
You. If the addition amount is as small as less than 50 kg, the gel swells.
Moisture becomes uneven, so it is not possible to obtain a super absorbent material,
Also, if the weight is higher than 100 kg, water from the gel
It is not suitable because separation becomes difficult. Subsequently, the formed gel is filtered and the resulting gel is obtained.
The gel was then dispersed in an organic solvent compatible with water.
While adding alkali while suppressing swelling,
The carboxyl group is returned to the salt form. Addition of organic solvent at this time
The amount varies depending on the type of gel and the degree of swelling.
20-30 kg per kg of absolutely dried cellulose derivative
You. If the added amount is too small, it will not be uniform salt form and it is too much
And the amount of organic solvent used increases, resulting in waste. Filtration is known
Using a filter cloth, a filtration device using a wire mesh, and a centrifugal dehydrator,
This is done by selecting the filter media mesh according to the gel situation.
You. Organic solvents should dissolve as much alkali as possible.
Are preferred, and monovalent alcohols such as methanol and ethanol
And glycerin are preferred. Above all, fibrous
To obtain a highly water-absorbing cellulose material, methanol
Is most suitable. The gel of the cellulose derivative converted to the salt form is water
And dried as it is, gels with water
Particles adhere to each other to form a hard resinous material. This one
Does not show high water absorption and cannot be used as is
Requires additional costs for grinding and dispersion. So
The salted gel is filtered to separate the gel from the solvent.
And then immersed again in an organic solvent compatible with water.
Water remaining in the gel
Cells that have been treated this way so they can be replaced
Heat-dry the gel of the loin derivative to absorb water-absorbing cellulose material
You can get a fee. Further, the water absorbing cell in the present invention
The shape of the loin material is fibrous, powdery, particulate, sheet
There is no particular limitation on the shape of the fiber,
Are better. According to the method of the present invention, an excellent superabsorbent material is obtained.
The reasons for it are not yet clear enough
But most importantly, the crosslinked cellulose derivative is expanded.
It is thought to be to moisturize. By swelling
One of the effects obtained is the reduction of water-soluble components in the gel.
It is. Crosslinked cellulose derivative used in the present invention
Is synthesized by crosslinking a water-soluble polymer as described above.
I do. In this case, there is a probability that a part of the water-soluble polymer is crosslinked.
Inevitably remain in the gel as a water-soluble component
No. And if this water-soluble component is present in a large amount in the gel
Then, when the gel is swollen, it becomes sticky,
It causes formation and leads to a decrease in water absorption capacity and gel strength.
You. Therefore, if the crosslinking density is theoretically increased,
In addition, it is necessary to remove water-soluble components,
Considering a method to wash cross-linked cellulose derivatives with water
However, in this case, the cellulose derivative is very
It absorbs a large amount of water and swells, so it has huge heat energy for drying
It is not realistic because it requires energy. So the cellulose derivative
Swelling is suppressed and evenly swelled to remove water-soluble components.
There is a demand for a method that uses water instead of water.
Swell with a mixture of organic solvents compatible with water
Swelling using a method of controlling water and using a mixture of water and salt
There is also a way to do this. However, the former is usually
It swells discontinuously due to the phenomenon called volume phase transition,
Moisture cannot be controlled arbitrarily;
Swelling can be effectively suppressed if no salt of
And a large amount of salt remains in the gel, which is not preferable. On the other hand, as in the present invention, the crosslinking
Water-insoluble and all carboxyl groups are in acid form
Disperse the cellulose derivative in water and add alkali to it.
Addition to partially neutralize carboxyl groups to form salt form
In this way, the degree of swelling is adjusted so that the degree of swelling becomes 3 to 30 g / g.
Adjusting the degree greatly increases discontinuous swelling due to volume phase transition
To convert the acid form of the carboxyl group to the salt form.
By changing the combination, it can be changed to almost continuous swelling
You can. On the other hand, according to the present invention, a water absorbing material having a high water absorption
Can be explained by simply removing the above water-soluble components.
It cannot be clarified, and it is actually estimated from the removal of water-soluble components.
Water absorption much higher than water is obtained. Such effects
Fruit develops in cellulose derivatives by swelling
Breakage of intermolecular hydrogen bonds or cross-linking points
Deforms the network to take in water between the molecular networks
This is presumed to be due to the fact that the state becomes easy. Therefore, the gel in this state is made compatible with water.
Wash with an organic solvent or immerse in the organic solvent
By replacing the water in the gel with an organic solvent,
Can be removed, thereby allowing the gel to dry easily.
Can be Moreover, in this case, it is formed by swelling
Most of the mesh structure preserved is preserved,
It is believed that aqueous develops. If the organic solvent
If the gel is dried without removing the water in the gel,
Hydrogen bonds are reformed by the effect of moisture in the water, changing the network structure.
Not only the shaping effect is reduced, but also the resulting water-absorbing material
However, high water-absorbing performance cannot be obtained. Further, the reason why high gel strength can be obtained is as follows.
Since the swelling of the cellulose derivative takes place in water,
Complete removal of water-soluble components in the gel,
When the carboxyl group of the cellulose derivative is converted to the acid form
New ester bond between molecules enhances cross-linking
It is possible. As described in detail above, according to the present invention,
High water absorption with significantly improved salt water absorption and gel strength
A cellulosic material can be obtained. [0030] The present invention will be described more specifically with reference to the following examples.
Although described, of course, the present invention is limited by these
Not something. In Examples and Comparative Examples,% and
All indicate weight%. Embodiment 1 20 g of bleached softwood bleached kraft pulp
The mixture was disintegrated with a mixer to give a floc. Put this floc into a reaction vessel
And 400 ml of isopropanol, 40 m of water
and 6.20 g of sodium hydroxide, and mixed for 1 hour
The mixture was stirred to obtain alkali cellulose. Monochrome to this
17.3 g of sodium acetate and 0.6 of epichlorohydrin
g was added, stirred for 30 minutes and left for another 30 minutes.
Next, attach a reflux condenser to the reaction vessel,
The mixture was heated at reflux in a bath for 3 hours. Glass fill the reaction product
70% methanol-water mixture
After washing thoroughly, wash twice with 100% methanol and vacuum
Dry in a dryer to obtain a fibrous crosslinked carboxymethyl
Rucellulose (hereinafter referred to as CMC) sodium salt 30
g (degree of substitution 1.0) was obtained. In a 500 ml beaker, the cross-linked CM
Take 3 g (absolutely dry) of C sodium salt, and add 1N hydrochloric acid 30
After adding 0 ml, the mixture was stirred for 30 minutes and allowed to stand for 30 minutes. this
The mixture was filtered through a glass filter (2G) to remove acid-
Isolating the crosslinked CMC having ruboxyl groups,
Repeat washing and filtration with pure water to remove excess acid
Was. Crosslinked CM having a carboxyl group of this acid form
C into a 300ml beaker and add 200ml of pure water
After dispersion, 6.64 ml of 1N aqueous sodium hydroxide solution
Add gel and partially neutralize with stirring to swell and gel
Was generated. The conversion to the salt form under these swelling conditions
The conversion ratio is 60% and the cross-linked CMC has a swelling degree of 28 g.
/ G. The above mixture was filtered with a glass filter (2G).
The gel was separated by filtration and transferred to a 200 ml beaker.
Disperse the gel by adding 60 ml of 100% methanol
Then, 1N sodium hydroxide-methanol solution 3.1
After adding 0 ml and stirring, the remaining acid-type carb
The xyl group was returned to the salt form. After standing for 1 hour, the gel is
Filter through a lath filter (2G) and filter
Immerse in 100 ml of ethanol, and remove the water in the gel
It was replaced by knol and removed. After standing for 1 hour, gel
And then filtered again with 100% methanol
After drying with a vacuum cleaner at 50 ° C. for 3 hours, a fibrous suction
An aqueous cellulose material was obtained. Using the obtained water-absorbing cellulose material,
The amount of water absorbed and the gel strength of the artificial urine were
Tested and evaluated its quality. Table 1 shows the results. [0035]Test method (1) Water absorption of artificial urine 0.8 g of the test material was dried in a 250 cm 10 cm square
And sealed in a nylon wire bag.
It was immersed in artificial urine fluid of the composition for 10 minutes to absorb water. this
Pull up, suspend, and drain for 10 minutes.
The amount of artificial urine absorbed per gram of sample was measured.
The amount of water absorption (g / g) was indicated by the amount. This water absorption is 4
If it is 0 g / g or more, it can be used practically. Artificial urine composition Ingredient% Urea 2.00 Sodium chloride 0.80 Magnesium sulfate 0.08 Calcium chloride 0.03 Pure water 97.09 [0036](2) Gel strength Place 1 g of absolutely dry sample material in a 100 ml weighing bottle,
20 ml of artificial urine was added to form a uniform gel. 2 hours
After standing, press the obtained gel with a finger to set the gel hardness
It was evaluated on a scale. The gel strength was rated as ○ (hard) and ◎ (very
Hard). ◎: Very hard ○: Hard △: soft ×: very soft [0037](3) Swelling degree According to Examples and Comparative Examples of the present invention, 1 g of absolutely dry sample material was used.
And gelled. That is, having an acid-type carboxyl group
Place the crosslinked CMC in a 300 ml beaker and add pure water 2
After dispersing in 100 ml, the specified aqueous solution of sodium hydroxide
The solution was added and swelled with stirring to form a gel.
This gel is 250cm Nylon 10cm square.
And hang it for 10 minutes.
And put it between the upper and lower filter papers in the bag.
And place it on a horizontal press table, on which 16cm in diameter,
Stack a stainless steel plate weighing 100 g and place 1k on it
g and apply pressure to the gel for 5 minutes.
The water present in the gap was absorbed by the filter paper. Then gel
Measure the weight of water and absorb water
Was used as the degree of swelling (g / g). Embodiment 2 Crosslinked CMC nut obtained in the same manner as in Example 1.
In a 500 ml beaker, add 3 g of sulfuric acid
Into 300 ml and stirred for 30 minutes, then released for 30 minutes
Placed. This mixture is filtered to remove the acid type carboxyl group.
Separated cross-linked CMC and further removal of excess acid
Washing and filtration with pure water were repeated in order to achieve this. This acid form
Place the crosslinked CMC in a 300 ml beaker and add pure water 2
After adding 00ml and dispersing, 1N sodium hydroxide aqueous solution
Add 3.32 ml of liquid and partially neutralize with stirring
Swell to form a gel. Under these swelling conditions,
30% conversion to salt form
The degree of swelling of the thorium salt was 15 g / g. The mixture was filtered as in Example 1.
To separate the gel and transferred to a 200 ml beaker. This game
After adding 60 ml of ethanol to the mixture and dispersing,
A sodium-ethanol solution (5.43 ml) was added and stirred.
While stirring, return the remaining acid-type carboxyl groups to the salt form.
did. After standing for 1 hour, the gel was filtered and 100% ethanol
100 ml was added to replace and remove water in the gel.
The gel was filtered by standing still for 1 hour, and then 100% ethanol again.
And then dried to obtain a fibrous water-absorbing material. This material
The artificial urine water absorption of the sample and the gel strength were measured, and the results were
It is shown in Table 1. Embodiment 3 Crosslinking agent (trade name: SUMITEX, NF-500K,
2.0 g, manufactured by Tomo Chemical Co., Ltd .;
X, Accelerator, MX, manufactured by Sumitomo Chemical)
0g and 297.0g of water to make 300g of a mixed solution.
And 20g of bleached softwood bleached kraft pulp
Dipped for 0 minutes. The mixture in the pulp is 24
g by filtering and pressing the excess mixture
Removed. The obtained sheet pulp is sufficiently dried at room temperature.
After drying, heat in a blow dryer at 140 ° C for 30 minutes.
To effect crosslinking. This crosslinked pulp is converted to a household mixer.
To disintegrate into floc. Put this floc into the reaction vessel
400ml of isopropanol, 40ml of water,
And 5.93 g of sodium hydroxide, and stirred for 1 hour
Thus, alkali cellulose was obtained. Monochloroacetic acid
Add 17.3 g of sodium and stir for 30 minutes.
It was left for 30 minutes. Next, install a reflux condenser in the reaction vessel.
And the mixture was heated at reflux in an oil bath for 3 hours. reaction
The product was filtered through a glass filter (2G) and 70%
After washing thoroughly with ethanol, wash twice with 100% methanol
And then dried in a vacuum dryer to form a fibrous cross-link
Thus, 30 g of CMC sodium salt (degree of substitution 1.0) was obtained. In a 500 ml beaker, the crosslinked CM
Take 3 g of C sodium salt and add 1.5N hydrochloric acid to 300 g
The mixture was stirred for 30 minutes and left for 30 minutes. This mix
The compound was filtered to separate the acid-form crosslinked CMC,
Washing and filtration with pure water were repeated to remove the acid. This
Crosslinked CMC having carboxyl group of acid type
Put in a 00ml beaker, add 200ml of pure water and disperse
Then, add 6.64 ml of 1N sodium hydroxide aqueous solution
To partially neutralize and swell while stirring to form a gel
I let it. The conversion rate to salt form under these swelling conditions
Is 60% and the cross-linked CMC has a swelling degree of 28 g / g.
there were. The mixture was filtered to separate the gel,
Transferred to a ml beaker. 100% methanol in this gel
After adding 60 ml and dispersing, add 1 N sodium hydroxide
Add 3.10 ml of the ethanol solution and stir while stirring.
The carboxyl group of the acid form was returned to the salt form. Leave for 1 hour
After that, the gel was filtered, and 100 ml of 100% methanol was added.
To remove the water in the gel. Let sit for one hour
Filter, wash again with 100% methanol and dry.
Thus, a fibrous water-absorbing material was obtained. Artificial using this material
Urine water absorption and gel strength were measured and the results are shown in Table 1.
did. Embodiment 4 Commercially available powdered CMC sodium salt (degree of substitution: 0.65,
Viscosity of 1% aqueous solution: 280 cps, trade name: Cellogen W
(SC, manufactured by Daiichi Kogyo Seiyaku) 30 g of isopropanol 3
33 ml, water 78 ml, sodium hydroxide 2 g, and
Charge 22 g of Tylene oxide into an autoclave,
Was reacted at 70 ° C. for 2 hours. Then the reaction mixture
Is neutralized with acetic acid and filtered to remove most of the reaction solvent.
Dried at 60 ° C for 4 hours
Cimethylcellulose sodium salt (hereinafter referred to as HECMC
Thorium salt) was prepared. This HECMC Nutri
Into a reaction vessel, and add isopropanol
600 ml, water 120 ml, and ethylene glycol
4.5 g of diglycidyl ether were mixed. In the reaction vessel
Install a reflux condenser and return the mixture in an oil bath for 2 hours
A cross-linking reaction was performed by flow heating. Mix the reaction mixture
And filtered with a 70% methanol filter.
After washing for 2 minutes, wash twice with 100% methanol and dry under vacuum
To obtain a crosslinked HECMC sodium salt
Was. In a 1 liter beaker, the crosslinked HE
Take 3 g of CMC sodium salt and add 0.7N hydrochloric acid 45
0 ml was added, stirred for 30 minutes, and left for 90 minutes. This
Of acid-type carboxyl group by filtration of the mixture of
HECMC separated to further remove excess acid
Washing and filtration with pure water were repeated. This acid type crosslinked
Put the HECMC in a 300 ml beaker and add 30
After adding 0 ml and dispersing, 1N sodium hydroxide aqueous solution
Add 3.32 ml, partially neutralize and stir while stirring.
Moistened to form a gel. Salt form under these swelling conditions
30% conversion to swelling of cross-linked HECMC
When the degree was measured, it was 25 g / g. The mixture
To separate the gel and transfer to a 200 ml beaker.
Was. 60 ml of 100% methanol is added to the gel and separated.
After dispersing, 1N sodium hydroxide-methanol solution 5.4
Add 3 ml and stir while stirring the remaining acid-type carbohydrate.
The xyl group was returned to the salt form. After standing for 1 hour, the gel was filtered,
Add 100 ml of 100% methanol to remove water in the gel
Replaced and removed. Let stand for 1 hour, filter the gel and re-
After washing with 100% methanol and drying, the powder
An aqueous material was obtained. Using this material, the amount of artificial urine absorbed and
The gel strength was measured and the results are shown in Table 1. Embodiment 5 0.1% nitric acid on bleached softwood kraft pulp
Add 154g of acid and 14g of acrylonitrile and mix well
did. Next, ceric nitrate as a graft polymerization initiator
Add 370mg of ammonium and graph for 1 hour at room temperature
The polymerization was carried out. The reaction product is thoroughly washed with water, filtered
After dehydration, 1000 ml of 3% aqueous sodium hydroxide solution
In addition, by heating at 100 ° C for 2 hours, the graph
The copolymerized pulp was hydrolyzed. This reaction product is
After separation by filtration and washing with a 76% aqueous methanol solution,
Vacuum dried to obtain hydrolyzate of graft copolymerized pulp
Was. Next, 5 g of this hydrolyzate was added to 50 g of isopropanol.
ml, 10 ml of water and 1.5 g of sodium hydroxide.
After stirring at room temperature for 1 hour,
4.4 g of thorium was added, and the mixture was further added at 40 ° C. for 3 hours.
Carboxymethylation to the hydrolysis product by heating for hours
, And washed with 70% methanol, followed by vacuum drying. This
Graft copolymerization carboxymethylated as in
A pulp hydrolyzate was obtained. The carboxymethylated product is placed in a plastic bag.
3 g of the hydrolyzate of the graft copolymerized pulp
Add 60ml of fixed hydrochloric acid and leave outside the plastic bag for 30 minutes
The mixture was rubbed by hand and left for 30 minutes. This mixture
To separate the acid-type graft copolymerized pulp,
Repeat washing and filtration with pure water to remove excess acid
Was. 300 ml of this acid type graft copolymerized pulp
Put into a car, add 150 ml of pure water and disperse.
Add 7.75 ml of aqueous sodium oxide solution and stir.
The gel was partially neutralized and swelled to form a gel. this
The conversion rate to the salt form under swelling conditions was 70%.
The degree of swelling of the copolymerized pulp was 28 g / g. The blend
The mixture was filtered to separate the gel and transferred to a 200 ml beaker.
did. After 90 ml of methanol was added to the gel and dispersed,
1.16 ml of 2N methanolic sodium hydroxide solution
While adding and stirring, the remaining acid-type carboxyl groups
Was returned to the salt form. After standing for 1 hour, the gel was filtered and 100%
Replace the water in the gel by adding 100 ml of methanol
Removed. The gel was filtered by allowing to stand for 1 hour, and then 100% again.
After washing with methanol and drying, a fibrous water-absorbing material
Got. Using this material, artificial urine absorption and gel strength
Was measured, and the results are shown in Table 1. Embodiment 6 To 10 g of the commercially available powdered sodium salt of CMC,
Add 3g of thorium and 80g of water, stir and mix for 1 hour
MC was dissolved. Next, add 3 g of epichlorohydrin
And further mix for 1 hour, then crosslink at 40 ° C for 6 hours
The reaction was performed. Generated gel with dimensions of 10 x 5 x 1 mm
And stirred in 500 ml of 70% methanol for 2 hours
did. The gel was filtered and 100% methanol 500m
After stirring for 1 hour in a l
Dried in a stove. This is crushed to form a particulate cross-linked
CMC sodium salt was obtained. This cross-linked CMC Nato
The lithium salt was treated in the same manner as in Example 1 to obtain a particulate water-absorbing material.
The material was obtained. Using this material, artificial urine water absorption and gel
The strength was measured, and the results are shown in Table 1. Embodiment 7 A crosslinked CMC having an acid type carboxyl group
When partially neutralizing with potash and swelling to form a gel
2.21 ml of 1N aqueous sodium hydroxide solution was added
A fibrous water-absorbing material was prepared in the same manner as in Example 1 except that it was used.
Water-absorbing material and gel using this material
The strength was measured, and the results are shown in Table 1. In addition, used
The conversion to the salt form under swelling conditions is 20%,
The degree of swelling of the obtained CMC was 4 g / g. Comparative Example 1 Prior to the acid form obtained in Example 1, a fibrous cross-linked
Of artificial urine absorption and gel using CMC sodium salt
The strength was measured, and the results are shown in Table 1. Comparative Example 2 The fibrous cross-linked prior to the acid form obtained in Example 3
Of artificial urine absorption and gel using CMC sodium salt
The strength was measured, and the results are shown in Table 1. Comparative Example 3 The powdered, crosslinked form before the acid form obtained in Example 4
Water absorption using artificial HECMC sodium salt
The gel strength was measured and the results are shown in Table 1. Comparative Example 4 Fibrous graft obtained in Example 5 before conversion into the acid form
Artificial urine absorption using polymerized CMC sodium salt
And the gel strength were measured, and the results are shown in Table 1. Comparative Example 5 Particulate cross-linked prior to the acid form obtained in Example 6
Of artificial urine absorption and gel using CMC sodium salt
The strength was measured, and the results are shown in Table 1. Comparative Example 6 A crosslinked CMC having an acid type carboxyl group
When gel is formed by partially neutralizing and swelling with potash
1.11 ml of 1N aqueous sodium hydroxide solution
Except that it was used in the same manner as in Example 1,
Obtain a water-absorbing material, and use this material to absorb artificial urine water and
The gel strength was measured and the results are shown in Table 1. In addition,
The conversion rate to the salt form under the swelling condition was 10%,
The degree of swelling of the bridged CMC was 2 g / g. Comparative Example 7 A crosslinked CMC having an acid type carboxyl group
When gel is formed by partially neutralizing and swelling with potash
8.86 ml of 1N aqueous sodium hydroxide solution
Except that it was used in the same manner as in Example 1,
Was. However, the degree of swelling is too high and extremely soft
Since it became a gel, it was possible to separate the gel by filtration.
No high water absorbing material could be obtained. What
The conversion rate to the salt form under the swelling conditions used is 80%.
The swelling degree of the crosslinked CMC was 60 g / g. Comparative Example 8 A crosslinked CMC having an acid type carboxyl group
After partially neutralizing with potassium and swelling to form a gel,
Do not convert the remaining acid-form carboxyl groups in the gel back to the salt form.
A fibrous water absorption was performed in the same manner as in Example 1 except that
Water-absorbing material and gel using this material
The strength was measured, and the results are shown in Table 1. Comparative Example 9 The same operation as in Example 1 was carried out to obtain an acid type carboxyl group.
Partially neutralizes the cross-linked CMC with alkali and swells
To form a gel, and the acid-type carbohydrate remaining in the gel.
After changing the xyl groups to the salt form, the gel was filtered. afterwards,
Without replacing the water in the gel with methanol
Dry to obtain a hard resinous water-absorbing material, and use this material
Measure the amount of artificial urine absorbed and the gel strength and display the results.
1 is shown. Comparative Example 10 The fibrous crosslinked CMC sodium obtained in Example 1
Do not change the carboxyl group to the acid form using 3 g of salt
And 63.3 g of a 48.8% aqueous solution of isopropanol.
A gel was formed by swelling, and the water content was changed in the same manner as in Example 1.
To obtain a fibrous water-absorbing material, and using this material
The amount of artificial urine absorbed and the gel strength were measured, and the results are shown in Table 1.
It was shown to. Swelling degree of cross-linked CMC under these swelling conditions
Was 5 g / g. [0058] [Table 1] As can be seen from Table 1, the cell according to the present invention
The superabsorbent material composed of the loin derivative absorbs artificial urine
The amount is high and the gel strength is excellent (Examples 1 to 7). This
On the other hand, it has a salt-type carboxyl group before changing to the acid form.
Crosslinked cellulose derivatives have slightly lower water absorption
Or equivalent, but the gel strength was extremely poor (Comparative Examples 1 to
5) Not suitable for practical use. Even if the same method as the present invention is used,
When the degree of moisture is low (Comparative Example 6), the water absorption is almost the same,
Gel strength is low, and carboxy
Alcohol-water solvent without changing the acid group to acid
When the gel is formed by swelling (Comparative Example 10), the water absorption becomes
Notably high, but low gel strength, both are not suitable for practical use
No. If the degree of swelling is too high according to the same method as the present invention,
(Comparative Example 7), the generated gel was so filtered that it could not be separated
It becomes soft and unprocessable. On the other hand,
Even if a gel is generated by partial swelling, the remaining acid type
The carboxyl group was not returned to the salt form (Comparative Example 8),
Alternatively, after separating the gel produced by filtration,
Remove any residual water that is compatible with water, such as methanol.
Without drying with an organic solvent (Comparative Example
9) The water absorption and gel strength are poor, making it impractical.
Was. [0060] Industrial Applicability The present invention can be synthesized with a relatively small amount of an organic solvent.
Aqueous solution containing various salts as well as pure water
Shows high water absorption, and gel strength after water absorption
Excellent handling for easy handling and use in a wide range of fields
Cellulose induction suitable for use in sanitary materials
The effect of providing a method for producing a water-absorbing material composed of a conductor
Play a fruit.

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Claims (1)

(57) [Claim 1] A cellulose derivative which is insolubilized in water by cross-linking and has all carboxyl groups in an acid form is dispersed in water, and then an alkali is added to neutralize the carboxyl group. Then, a cellulose derivative gel having a swelling degree of 3 to 30 g / g is produced, and then the gel is separated from water, placed in an organic solvent compatible with water, and an alkali is added thereto to form an acid form remaining in the gel. Returning the carboxyl group of the salt to a salt form, further separating the gel from the solvent, removing and replacing the water in the gel with the organic solvent, and drying. A method for producing a water-absorbing cellulose material having excellent gel strength.