JPH0720548B2 - Liquid-absorbent complex - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a liquid-absorbent composite, and more specifically,
Suitable for sanitary napkins, hygiene / medical products such as disposable diapers, and freshness-retaining agents such as vegetables, agricultural and forestry fields such as water-retaining agents, and other applications that need to retain liquids and liquids that have absorbed liquids. The present invention relates to a liquid-absorbent composite.

[Conventional technology and its problems]

In recent years, so-called water-absorbing polymers that absorb several tens to several hundred times their own weight of water have been developed, including sanitary products such as sanitary napkins and disposable diapers, water retention and water supply materials in the fields of agriculture and forestry, civil engineering, etc. Is used for.

As the water-absorbing polymer, a cross-linked product of polyacrylic acid salt or starch-acrylic acid graft polymer, a hydrolyzate of cellulose-acrylonitrile graft polymer, a hydrolyzate of vinyl acetate-acrylic acid ester copolymer, etc. are known. is there. Such a water-absorbent polymer has an excellent absorption performance for a low-viscosity liquid such as water or urine, can absorb quickly and in large amounts, and various improvements have been proposed.

However, for highly viscous liquids represented by blood, it is made porous (JP-A-55-71728) and an organic and / or inorganic water-soluble salt is added (JP-A-58-501107). Gazette), mixing with hydrophilic fibers such as pulp (JP-A-59-8665)
No. 7) has been proposed, but the effect is not sufficient.

It is desired to develop a water-absorbing polymer which is excellent in absorption performance, that is, in absorption amount, absorption rate, and absorption power, even for a highly viscous liquid as soon as possible.

[Means for solving problems]

Under the above circumstances, the inventors of the present invention absorbed water, urine, and low-viscosity liquids such as serous body fluids, blood, high-viscosity liquids such as body fluids and loose stools, which are excellent in absorption amount, absorption rate, and absorption power. As a result of earnestly studying the material, a specific amount of a water-insoluble inorganic substance and a fibrous substance exhibiting a water-insoluble hydrophilic property have been added to the water-absorbent polymer, and by immobilizing it, it has an unprecedented excellent absorption performance. They have found that a composite can be obtained, and have completed the present invention.

That is, the present invention, (A) on the surface of the water-absorbing polymer, (B)
Water-insoluble inorganic substance selected from the group consisting of alumina, silica, zeolite, montmorillonite group clay and kaolinite group clay, and (C) water-insoluble fiber length 50 mm or less selected from the group consisting of cellulose powder, pulp and rayon It is a liquid-absorbent composite in which a hydrophilic fibrous substance is immobilized, and its composite ratio (polymerization ratio) is (A) :( B):
(C) = 100: 5 to 1200: 5 to 1200, bulk specific gravity of 0.03 to 0.7 g / cc
And a liquid-absorbent composite.

The water-absorbing polymer used in the present invention may be any polymer as long as it is generally water-absorbing.
For example, polyacrylic acid salt or crosslinked product thereof, polyethylene oxide, polyvinylpyrrolidone, crosslinked product of sulfonated polystyrene and polyvinylpyridine, saponified product of starch-poly (meth) acrylonitrile graft copolymer, starch-poly (meth) acrylic acid (And its salt)
Examples thereof include a graft copolymer (and a crosslinked product thereof), a reaction product of polyvinyl alcohol and maleic anhydride (and a salt thereof), and a hydrolyzate of a starch-poly (meth) acrylic ester graft copolymer. Further, polyvinyl alcohol sulfonate, polyvinyl alcohol-acrylic acid graft copolymer, etc. can be exemplified. Preferred is a polymer of a water-soluble ethylenically unsaturated monomer containing acrylic acid or an acrylic acid salt as a main component or a cross-linked product thereof, and any production method thereof may be used.

Two or more kinds of these polymers may be used. The water-absorbent polymer is a polymer that absorbs 20 cc / g or more of water, and has a shape such as powder, granules, lumps, and sheets, for producing the composite of the present invention.
Any of them can be used. In the case of powder or granule, the particle size is preferably 10 to 3000 μm, more preferably 15 to 1000 μm.

As the inorganic substance used in the present invention, the essential condition is that it is substantially insoluble in water, alumina, silica,
Zeolite, Montmorillonite clay (bentonite)
And kaolinite clay (kaolin). The particle size of the water-insoluble inorganic substance is not particularly limited, but it is preferably used if it is 1500 μm or less, and particularly preferably 500 μm or less.

The water-insoluble hydrophilic fibrous substance used in the present invention is selected from the group consisting of natural cellulose having wettability and liquid conductivity peculiar to the water-insoluble fibrous substance, cellulose powder which is artificial cellulose, pulp and rayon. . or,
Hydrophobic fibrous substances such as polyester, polyethylene, polypropylene, polyvinyl chloride, acrylic, and nylon are mixed with these water-insoluble hydrophilic fibrous substances for the purpose of imparting functions such as fixation by heat fusion. It can also be used. Hydrophobic fibrous substances can change the mixing ratio in a large range depending on the application as long as the hydrophilicity is not impaired.
It is desirable that the content be 80% by weight or more. The form of these fibrous substances may be any of long fibers to short fibers and fine powder. The fiber length is preferably 50 mm or less, more preferably 40 mm or less.

The composite ratio of the water-absorbent polymer, the water-insoluble inorganic substance, and the water-insoluble hydrophilic fibrous substance is 5 to 1200 parts by weight of the water-insoluble inorganic substance and 5 to 100 parts by weight of the water-insoluble hydrophilic fibrous substance. 1200 parts by weight, preferably with respect to 100 parts by weight of the water-absorbing polymer, 10-800 parts by weight of the water-insoluble inorganic substance, 10-1000 parts by weight of the water-insoluble hydrophilic fibrous substance, more preferably 100 parts by weight of the water-absorbing polymer. In contrast, 20-500 parts by weight of water-insoluble inorganic substance, water-insoluble hydrophilic fibrous substance 2
0 to 800 parts by weight. The effect of the present invention is not recognized even if any of these constituent components is lacking, which is not the intention of the present invention. When the content of the water-insoluble inorganic substance is less than 5 parts by weight, the absorption rate and absorption capacity of the water-absorbent polymer are small, which is not preferable. On the other hand, if it exceeds 1200 parts by weight, the absorption amount of the composite becomes small and it is not fixed to the polymer, so that the object of the present invention cannot be achieved. In the case of a water-insoluble hydrophilic fibrous substance, when the content is less than 5 parts by weight, the effect of the liquid-conducting property of the liquid-absorbing complex is small, and when it exceeds 1200 parts by weight, the absorption of the liquid-absorbing complex is absorbed. The amount is too small to achieve the object of the present invention. The composite ratio of the water-insoluble inorganic substance and the water-insoluble hydrophilic fibrous substance can be freely changed within the above range depending on the type and application of the liquid to be absorbed.

As a method for producing the liquid-absorbent composite of the present invention, a known method is used, but the following method is preferably used.

That is, a method of adding a water-insoluble inorganic substance and a water-insoluble hydrophilic fibrous substance in a state where the water-absorbent polymer is sufficiently swollen is used, and for example, the swollen polymer, the water-insoluble inorganic substance and the water-insoluble hydrophilic substance are added to a kneader mixer. Method of adding a water-soluble fibrous substance, mixing and drying, a method of sequentially adding a water-absorbing polymer, water, a water-insoluble inorganic substance and a water-insoluble hydrophilic fibrous substance in an organic solvent with stirring, and filtering and drying after mixing ,
A method in which a water-insoluble inorganic substance and water are mixed, a water-absorbent polymer and a water-insoluble hydrophilic fibrous substance are sequentially added to a screw rotary vane type mixer, and the mixture is then dried is exemplified. Further, to the water-soluble ethylenically unsaturated monomer containing a water-soluble ethylenically unsaturated monomer or a partial cross-linking agent, after adding a water-insoluble inorganic substance, a water-insoluble hydrophilic fibrous substance, polymerization,
A drying method or the like is also used, and the manufacturing method thereof is not particularly limited. Further, the liquid-absorbent composite obtained after drying can be pulverized and treated if necessary.

The liquid-absorbent composite of the present invention thus produced has a bulk specific gravity of 0.03 to 0.7 g / cc, preferably 0.05 to 0.6 g / cc. A composite with a bulk specific gravity of less than 0.03 g / cc becomes too bulky and difficult to handle.
If it exceeds, the desired absorption performance cannot be obtained.

(A) Water-absorbent polymer of the absorbent composite of the present invention, (B)
The composite state of the water-insoluble inorganic substance and (C) the water-insoluble hydrophilic fibrous substance is as follows. That is,
The water-insoluble hydrophilic fibrous substance and the water-insoluble inorganic substance are immobilized on the surface of the water-absorbent polymer in the following states.

<Water-insoluble hydrophilic fibrous substance> Fibers are partially or completely embedded in the polymer.

 Fibers are attached to the polymer surface.

The fibers are intertwined with each other, and some of the fibers are embedded in the polymer or attached to the polymer surface.

 The polymer and the fiber are bonded via an inorganic substance.

<Water-insoluble inorganic substance> The inorganic substance is partially or completely embedded in the polymer.

 Inorganic substances are attached to the polymer surface.

An inorganic substance is attached to the fibers of the above <fibrous substance>.

The inorganic substances are agglomerated with each other, and a part of the inorganic substances is embedded in the polymer or adheres to the polymer surface.

Examples of the complexed state of the (A) water-absorbent polymer, (B) water-insoluble inorganic substance, and (C) water-insoluble hydrophilic fibrous substance include the above, but the present invention is not limited thereto. It is not necessary that the three components (A), (B), and (C) are substantially combined.

[Work]

The improvement of the liquid absorbability by the water-insoluble inorganic substance and the water-insoluble hydrophilic fibrous substance in the liquid-absorbent composite in the present invention is particularly remarkable in the case of a highly viscous liquid, but its action is as follows. It is thought that it was demonstrated.

Since the water-absorbent polymer is coated with a water-insoluble hydrophilic fibrous substance, it has good compatibility with the liquid to be absorbed, and even when the liquid does not come into contact with the polymer, the liquid coats the water-absorbent polymer. As long as it comes into contact with the hydrophilic fibrous substance, the liquid can be carried to the polymer due to the liquid-conducting effect of the fiber, and the polymer can swell.

The inorganic substance used in the present invention is preferably one which is substantially insoluble in water and has a certain degree of hygroscopicity, and this inorganic substance is partially contained in the polymer. This is because the surface of the water-absorbent polymer having a smooth surface is covered with the finely powdered inorganic substance in a dense state, so that a capillary phenomenon occurs between the particles of the inorganic substance and the absorption performance of the water-absorbent polymer is activated. Conceivable. Therefore, by combining with a water-absorbing polymer of both the water-insoluble inorganic substance and the water-insoluble hydrophilic fibrous substance, the improvement of the performance targeted by the present invention is exhibited.

〔Example〕

The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

The saturated absorption amount, absorption rate, and absorption capacity were evaluated by the following methods. Saline was used as a representative example of the low-viscosity liquid, and defibrinated horse blood was used as a representative example of the high-viscosity liquid.

(1) Saturated absorption amount The dried liquid-absorbent complex was immersed in a sufficient amount of physiological saline or horse blood (defibrinated, Japan Biomaterials Center, Publisher) and left for 30 minutes. Then suction and permeation (filter paper No.2, diameter 1
25 mm) and weighed. The same operation was performed on the system without the liquid-absorbent complex (that is, only the filter paper), and the weight was measured. From these, the saturated absorption amount of the liquid-absorbent composite was determined by the following formula.

W: Weight of water-absorbent polymer (A) in the absorbent composite (g) W ₁ : Weight of absorbent composite after absorbing liquid (g) W ₀ : Weight of filter paper after absorbing liquid (g) (2-1) Absorption rate (a) The absorption rate is measured using the apparatus shown in FIG. The upper port 1 of the buret is plugged, and the measurement table 2 and the air port 3 are set at a constant height. 0.3 g of the liquid-absorbent complex 5 was placed on the glass filter (No. 1) 4 having a diameter of 70 mm in the measuring table 2, and the value of horse blood absorbed for 20 minutes thereafter was expressed as the absorption rate (a).

(2-2) Absorption rate (b) (2-1) By the same experimental method as the measurement of the absorption rate (a), the water-absorbing polymer (A) fixed to 0.3 g was 1
The value of physiological saline absorbed per minute was expressed as the absorption rate (b).

(3) Absorbency To 0.05 g of the liquid-absorbent complex, add horse blood or physiological saline with a dropper.
0.5 cc was dropped, and the degree of absorption was visually observed and expressed in four stages.

Example 1 230 ml of cyclohexane in a 500 ml four-neck round bottom flask equipped with a stirrer, a reflux condenser, a dropping funnel and a nitrogen introducing tube.
1.0 g of ethyl cellulose (N-100: manufactured by Hercules) was charged and the temperature was raised to 75 ° C. Separately, 30 g of acrylic acid was neutralized in an Erlenmeyer flask with an aqueous solution in which 13.4 g of caustic soda was dissolved in 39 g of water. The monomer concentration in the monomer aqueous solution was 45% by weight (water content 55% by weight). Then, 50 mg of potassium persulfate and 65.5 mg of polyoxyethylene glycol diacrylate having an average number of oxyethylene units of 12 were added and uniformly dissolved. This monomer aqueous solution was added to the above 4
The mixture was added dropwise to the one-necked flask under a nitrogen atmosphere for 1.5 hours for polymerization, and then maintained at a temperature of 70 to 75 ° C. for 0.5 hours to complete the polymerization.

The polymer was filtered and dried under reduced pressure at 80 ° C to obtain a water-absorbent polymer (A-1).

20 g of water-absorbent polymer (A-1), 100 g of deionized water, 10 g of bentonite, cellulose powder (CF11 of Whatman)
A liquid-absorbent composite was obtained by kneading with 10 g of a fiber length of 500 μm using a twin-screw kneader for about 10 minutes and then drying under reduced pressure at 80 ° C.

When confirmed by an electron microscope, it was confirmed that bentonite and cellulose powder were immobilized on the surface of the water absorbent polymer (A-1). The bulk specific gravity of this composite was 0.24 g / cc.

Example 2 230 ml of cyclohexane in a 500 ml four-neck round bottom flask equipped with a stirrer, a reflux condenser, a dropping roll and a nitrogen introduction tube.
1.0 g of ethyl cellulose (N-100: manufactured by Hercules) was charged and the temperature was raised to 75 ° C. Separately, 30 g of acrylic acid was neutralized in an Erlenmeyer flask with an aqueous solution in which 13.4 g of caustic soda was dissolved in 39 g of water. The monomer concentration in the monomer aqueous solution was 45% by weight (water content 55% by weight). Then, 50 mg of potassium persulfate was added and uniformly dissolved. This monomer aqueous solution was added dropwise to the above four-necked flask under a nitrogen atmosphere for 1.5 hours to carry out polymerization, and then maintained at a temperature of 70 to 75 ° C. for 0.5 hour to complete the polymerization.

After this, the water content in the polymer suspended in cyclohexane was reduced to 35% by azeotropic dehydration (cyclohexane was refluxed).
It was set to% by weight.

After this, tetraglycerose tetraglycidyl ether (trade name Denacol EX-512, manufactured by Nagase & Co., Ltd.) 0.0
An aqueous solution prepared by dissolving 3 g in 1 ml of water was added at a temperature of 73 ° C., maintained at this temperature for 2 hours, cyclohexane was removed, and the polymer was dried under reduced pressure at 80 ° C. to obtain a water-absorbing polymer ( A-2) was obtained.

Using 20 g of the water-absorbent polymer (A-2), 200 g of ion-exchanged water, 10 g of bentonite and 10 g of cellulose powder, the bentonite and the cellulose powder were fixed to the water-absorbent polymer (A-2) by the same operation as in Example 1. A liquid-absorbent composite having a bulk specific gravity of 0.27 g / cc was obtained.

Example 3 The same procedure as in Example 1 was repeated except that the composition of the liquid-absorbent composite was changed to 10 g of alumina instead of bentonite and 60 g of ion-exchanged water, and alumina and cellulose powder were added to the water-absorbent polymer (A-1). A liquid-absorbent complex was obtained which was immobilized and had a bulk specific gravity of 0.21 g / cc.

Example 4 A water-absorbent polymer was prepared in the same manner as in Example 1, except that the composition of the liquid-absorbent composite was changed to 20 g of pulp (fiber length: 5 mm) instead of cellulose powder, and the water-absorbent polymer (A-1) was changed to 10 g. A liquid-absorbent composite having bentonite and pulp immobilized on (A-1) and having a bulk specific gravity of 0.26 g / cc was obtained.

Example 5 A white powdery water-insoluble water-absorbent polymer (A-3) was produced from corn starch, acrylic acid, acrylamide and ethylene glycol dimethacrylate according to the method of Example 4 of JP-A-61-62463. did.

Using this water-absorbent polymer (A-3), bentonite and cellulose powder were immobilized on the water-absorbent polymer (A-3) by the same operation as in Example 1, and the bulk specific gravity of the composite was 0.22 g / cc. A liquid-absorbent composite of

Example 6 2 g of bentonite and 10 parts of water were added to a screw rotary vane type mixer.
After mixing 0 g, the water-absorbing polymer used in Example 1 (A
-1) 20g and 2g of cellulose powder were added sequentially, and kneaded for 5 minutes and dried under reduced pressure at 80 ° C to fix bentonite and cellulose powder to the water-absorbent polymer (A-1), and the bulk specific gravity of the composite. Was obtained to obtain a liquid-absorbent complex having a concentration of 0.52 g / cc.

Example 7 The composition of the liquid-absorbent composite in Example 1 was bentonite 20.
Bentonite and cellulose powder were fixed to the water-absorbent polymer (A-1) by the same procedure except that the amount of cellulose powder was changed to 0 g and 200 g of cellulose powder, and the bulk specific gravity of the composite was increased.
A liquid-absorbent composite having 0.08 g / cc was obtained.

Comparative Example 1 The water absorbent polymer (A-1) used in Example 1 was used as Comparative Example 1.

Comparative Example 2 A liquid absorbent in which bentonite was immobilized on the water-absorbing polymer (A-1) and the bulk specific gravity of the composite was 0.81 g / cc by the same operation as in Example 1 except that the cellulose powder was removed. A sex complex was obtained.

Comparative Example 3 Liquid absorbing properties in which cellulose powder was immobilized on the water-absorbent polymer (A-1) and the bulk specific gravity of the composite was 0.31 g / cc by the same operation as in Example 1 except that bentonite was removed. A complex was obtained.

Comparative Example 4 The water-absorbent polymer (A-1), bentonite and cellulose powder were mixed by the same operation as in Example 1 except that ion-exchanged water was not added. When confirmed by an electron microscope, it was confirmed that the bentonite and the cellulose powder were not immobilized on the surface of the water absorbent polymer (A-1). The bulk specific gravity of the mixture was 0.25 g / cc.

The saturated absorption amount, the absorption speed, and the absorption power of the liquid-absorbent composites obtained in Examples 1 to 7 and Comparative Examples 1 to 4 were evaluated.

The results are shown in Tables 1 and 2.

As is clear from Table 1 and Table 2, the liquid-supplying complex of the present invention showed excellent properties in a low-viscosity liquid and a high-viscosity liquid as compared with other comparative examples. In particular, it has shown unprecedented excellent absorption performance in saturated absorption amount, absorption speed, and absorption power for highly viscous liquids.

[Brief description of drawings]

 FIG. 1 is a schematic sectional view of an absorption rate measuring device. 1: Top of burette 2: Measuring stand 3: Air port 4: Glass filter 5: Absorbent complex

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location A61F 13/46 (56) References JP 61-58657 (JP, A) JP 59- 105448 (JP, A) JP 52-59086 (JP, A) JP 60-99339 (JP, A) JP 56-89839 (JP, A) Actual development JP 60-82498 (JP, U) Actual public Sho 60-31716 (JP, Y2)

Claims (3)

[Claims] 1. A water-insoluble inorganic substance selected from the group consisting of alumina, silica, zeolite, montmorillonite group clay and kaolinite group clay on the surface of (A) water-absorbing polymer, and (C) cellulose powder. , A liquid-insoluble hydrophilic fibrous substance having a fiber length of 50 mm or less selected from the group consisting of pulp and rayon, and having a composite ratio (weight ratio) (A): ( B):
(C) = 100: 5 to 1200: 5 to 1200, bulk specific gravity of 0.03 to 0.7 g / cc
And a liquid-absorbent composite. 2. The liquid absorbent according to claim 1, wherein the water-absorbing polymer is a polymer of a water-soluble ethylenically unsaturated monomer containing acrylic acid or an acrylic acid salt as a main component, or a cross-linked product thereof. Sex complex. 3. The liquid-absorbent composite according to claim 1, wherein the water-insoluble hydrophilic fibrous substance is selected from natural cellulose and artificial cellulose.