JPH0967750A - Antimicrobial water absorbing sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare an antimicrobial water absorbing sheet, capable of maintaining a sheetlike form even after absorbing a liquid and useful as sanitary materials, etc., by forming a complex sheet from pulp fibers prepared by immobilizing a cationic antimicrobial substance on a part of carboxyalkyl groups according to ion exchange and capable of gelling with synthetic fibers. SOLUTION: This antimicrobial water absorbing sheet comprises pulp fibers, prepared by immobilizing a cationic antimicrobial substance (a benzalkonium, etc.) in a part of carboxyalkyl groups according to the ion exchange and having cross-linkage bonds and the carboxyalkyl groups in the form of a complex sheet with synthetic fibers. The resultant sheet is flexible and excellent in antimicrobial performances and has high liquid and water absorbing performances.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an antibacterial water-absorbent sheet composed of a composite sheet containing synthetic fibers and pulp fibers. More specifically, the present invention relates to an antibacterial water-absorbing material comprising a composite fiber containing a pulp fiber having a crosslinked carboxyalkyl group, a part of the carboxyalkyl group having a cationic antibacterial substance fixed by ion exchange. It is a flexible sheet that is flexible, has high liquid absorption performance, and has antibacterial properties, and can be used in a wide range of fields such as various sanitary materials, agricultural materials, food packaging materials, civil engineering and construction materials, etc. The present invention relates to a water absorbent sheet.

[0002]

2. Description of the Related Art In recent years, a group of materials called superabsorbent resins have been known as water-absorbing materials for aqueous solutions containing salts such as water or saline. Basically, these resin materials have a chemical structure in which a water-soluble polymer is slightly crosslinked to make it insoluble in water. Examples of such a highly water-absorbent material include, for example, starch obtained by graft-polymerizing acrylonitrile and then hydrolyzing it, starch obtained by graft-polymerizing an acrylic acid metal salt, and acrylic acid polymerized with a copolymerizable cross-linking agent. A large number of crosslinking resins, hydrolysates of methyl methacrylate-vinyl acetate copolymers, etc. have been proposed, and some of them have been put into practical use.

Cotton, pulp, paper, cloth, sponge, etc., which are known as traditional water-absorbing materials, absorb water by a capillary phenomenon, whereas the superabsorbent resin described above has a principle of absorbing water. Because it is osmotic, it can absorb much more water than capillarity. Further, the highly water-absorbent resin has an excellent feature that it does not easily re-emit water even when pressure is applied in a water-absorbing state. Therefore, as applications of super absorbent resin, disposable paper diapers, sanitary materials such as sanitary products, soil water retention materials, agricultural material fields such as nursery sheets, food field such as food freshness-retaining materials, dehydration materials, and building dew condensation prevention. Widely used as building materials such as sheets.

By the way, as a water-absorbent material having a sheet shape, a water-absorbent sheet in which the above-mentioned super absorbent resin is sandwiched between paper, non-woven fabric and pulp sheet is known. In addition, for example, JP-A-3-269144. The publication discloses a highly water-absorbent nonwoven sheet containing at least 5 weight percent of water-swellable carboxymethyl cellulose fibers having a degree of etherification of 0.2 or more and a tensile strength of 1.8 g / d or more. On the other hand, as the tendency toward cleanliness has increased in recent years, materials having antibacterial properties have attracted widespread attention in various fields. For example, in the medical field where nosocomial infections are a problem,
The use of antibacterial products such as fibers, non-woven sheets, paper sheets, and resin molded products in the food field where hygiene is important and in various other situations where the purpose is to suppress the growth of bacteria. became. Among these, the applications of the water-absorbent sheet material include sanitary materials, agricultural materials field, food field, building materials, etc., like the above-mentioned super absorbent resin, but among these applications, antibacterial properties are required. Is often seen.

[0005]

SUMMARY OF THE INVENTION In view of the above situation, the present inventors diligently studied a water-absorbent sheet material having antibacterial properties, and as a result, as a method of imparting antibacterial properties to the water-absorbent sheet, crosslinking was performed. Further, it was found that it is effective to immobilize the cationic antibacterial substance on a part of the carboxyalkyl group by ion exchange, and the present invention has been completed. An object of the present invention is to provide a water-absorbent sheet having excellent antibacterial performance and high liquid water absorption performance, and having an antibacterial property capable of maintaining a sheet-like form even after absorbing liquid.

[0006]

The present invention comprises a synthetic fiber,
In an antibacterial water-absorbent sheet consisting of a composite sheet containing pulp fibers having a crosslinked carboxyalkyl group,
An antibacterial water-absorbing sheet, characterized in that a cationic antibacterial substance is fixed to a part of the carboxyalkyl group by ion exchange.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As the thermoplastic resin used in the synthetic fiber used in the present invention, known resins can be used as they are, and examples thereof include polyolefin resins, polyester resins, polyamide resins, and poly resins. Acrylic ester-based resins, polyurethane-based resins and the like can be mentioned, and these are selected and used alone or as a mixture. The synthetic fiber is a non-woven fabric obtained by the spunbond method in which the above resin is heated and melt-spun and the spun continuous filament group is collected to form a web, and the spun continuous filament is spun. Non-woven fabric obtained by a card method or a wet method of laminating staples in a sheet form, a melt blown non-woven fabric, and the like,
The method for producing the woven fabric is not particularly limited.

The fineness of the synthetic fiber is not particularly limited, but 0.
It is preferably in the range of 02 to 10 denier. When the fineness of the fiber exceeds 10 denier and becomes thicker, the flexibility of the non-woven fabric decreases, and the flexibility, texture and processability of the water absorbent sheet deteriorate. The fiber fineness is 0.02
When it is less than denier, it becomes extremely difficult to produce fibers having stable properties. Examples of the pulp fibers used in the present invention include pulp fibers produced from wood and non-wood pulp fibers produced from herbs.

Pulp fibers produced from wood include
Craft pulp method, sulfite method, soda method, polysulfite method, etc. of softwood wood or hardwood wood, chemical pulp fibers cooked, softwood wood refiner, mechanical pulp fibers pulped by a mechanical grinding force such as a grinder, or Used pulp fibers may be used alone or in combination, and these pulp fibers may be used unbleached or bleached as desired. Non-wood pulp fibers produced from herbs include, for example, cotton, Manila hemp, flax, straw, bamboo, bagasse, kenaf, mulberry, Sanpei, etc. These are digested in the same manner as in the case of wood pulp. It is made into pulp fiber.

In the present invention, a known method can be used as a method for producing a composite sheet containing synthetic fibers and pulp fibers which is preferably used. For example, "Research
Disclosure, 17060, June 1978 ", JP-A-5-
No. 253160, JP-A-5-277053,
As described in JP-A-5-285083, a nonwoven fabric made of synthetic fibers and a paper sheet are laminated to form a laminated body, and a water jet stream is jetted from the paper sheet side to entangle the fibers with each other to form one body. The composite sheet obtained by the method of making the compound has excellent texture and processability.

The composite sheet used in the present invention may be a composite sheet prepared by preliminarily mixing synthetic short fibers and pulp fibers and forming a web by a dry or wet method. In this case, it is necessary to partially bond the synthetic fibers to each other in order to maintain the wet tensile strength of the composite sheet. As a method of partially adhering synthetic fibers to each other,
Any known method may be used, such as a method of spraying an adhesive and then heating and bonding, a method of mixing heat fusion fibers and bonding by heating, a method by needle punching, a method by stitch bonding, etc. it can.

In the present invention, the blending ratio of the synthetic fiber and the pulp fiber constituting the composite sheet is adjusted so that the pulp fiber is 1 to 19 with respect to 1 synthetic fiber in absolute dry weight. When the ratio of the pulp fibers to the synthetic fibers is less than 1, the amount of the pulp fibers to the synthetic fibers becomes relatively small, and the water absorption of the obtained sheet becomes poor. On the other hand, when the proportion of pulp fibers is more than 19, the entanglement method using a water jet flow makes it difficult for sufficient entanglement of synthetic fibers and pulp fibers to occur, and when the obtained sheet is made to absorb water, it swells. The pulp fibers that have fallen off easily
Furthermore, the wet tensile strength is also reduced, which is not suitable.

In order to make the composite sheet containing the pulp fiber of the present invention a water absorbent material, an aqueous reaction liquid comprising a pulp fiber constituting the composite sheet, a carboxyalkylating agent, an alkali metal hydroxide and a cross-linking agent is used. It is necessary to add a carboxyalkyl group to the pulp fiber to give a crosslinked carboxyalkyl group. As the carboxyalkylating agent used in this aqueous reaction solution, an alkali metal salt of halocarboxylic acid is used. As the halocarboxylic acid alkali metal salt, monochloroacetic acid alkali metal salt, monobromoacetic acid alkali metal salt, α-chloropropionic acid alkali metal salt, β-chloropropionic acid alkali metal salt, α-bromopropionic acid alkali metal salt, β-bromo Those having 3 or less carbon atoms such as an alkali metal propionate are preferable, and these can be used alone or by appropriately selecting and mixing them. In terms of cost, sodium monochloroacetate is cheap, so it is recommended to use it.

Sodium hydroxide is most preferred as the alkali metal hydroxide, but other alkali metal hydroxides such as lithium hydroxide, potassium hydroxide, rubidium hydroxide and cesium hydroxide can also be used. As the cross-linking agent, a cross-linking agent that cross-links with pulp fibers in an alkaline aqueous reaction solution, has a boiling point as high as possible, and is almost non-volatile. In the present invention, for the purpose of improving the reaction efficiency, after including an aqueous reaction solution in a part or all of the composite sheet containing pulp fibers, the step of evaporating and removing the water content of the aqueous reaction solution is included. Low boiling point cross-linking agents that volatilize during are not suitable.

Examples of the crosslinking agent usable in the present invention include ethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, polyethylene glycol diglycidyl ether, and polyepoxy compounds such as diepoxybutane, divinyl sulfone, And at least one kind of divinyl compound such as methylenebisacrylamide, polyvalent halogen compound such as dichloropropanol, dibromopropanol, and dichloroacetic acid, and polyvalent aziridine compound are appropriately selected and used. Epichlorohydrin, which is often used for cross-linking cellulose derivatives and can impart excellent pure water absorption performance, is not suitable for the present invention because of its low boiling point.

The above-mentioned carboxyalkylating agent, alkali metal hydroxide and crosslinking agent are dissolved in water to give an aqueous reaction solution. The proportion of water based on the total weight in this aqueous reaction solution cannot be uniquely defined because the solubility varies depending on the type of carboxyalkylating agent or alkali metal hydroxide used, but the proportion of water within the range of solubility. The smaller the amount, the less the carboxyalkylating agent is decomposed by water, and the less energy cost is required in the subsequent evaporation of water after containing the aqueous reaction solution, which is advantageous. However, if the concentration is too high, the aqueous reaction solution becomes unstable and it becomes difficult to handle, so in the present invention, the ratio of water to the total weight of the aqueous reaction solution is, when sodium hydroxide is used,
A carboxyalkylating agent, an alkali metal hydroxide, and a crosslinking agent are dissolved in water so as to be 60 to 90%. The lower limit of the proportion of this water is the carboxyalkylating agent used,
The solubility varies depending on the type of alkali metal hydroxide and the type of cross-linking agent, and thus varies slightly.

The mixing molar ratio of the carboxyalkylating agent and the alkali metal hydroxide is adjusted to 0.8 to 1.2 for the alkali metal hydroxide / carboxyalkylating agent. The more it deviates from this range, one of the chemicals remains unreacted, which is uneconomical. The amount of the cross-linking agent mixed varies depending on the type of cross-linking agent or reaction conditions,
It is 0.1 to 30% by weight based on the weight of cellulose. next,
The composite sheet is impregnated with the aqueous reaction solution prepared as described above. The appropriate impregnation amount is such that the molar ratio of the carboxyalkylating agent to the glucose residue is 0.8 to 2.0 (mol / mol) of carboxyalkylating agent / glucose residue. When the molar ratio is less than 0.8, it becomes impossible to obtain a degree of substitution higher than 0.35. Considering that a cationic antibacterial substance is fixed to some carboxyalkyl groups as in the present invention, the water absorption is high. I can't get the material. On the contrary, even if the above molar ratio is added more than 2.0, the degree of substitution hardly increases, which is economically disadvantageous. Further, it is advantageous to increase the total molar ratio by repeating the reaction at least twice, but it is disadvantageous in terms of cost, although the substitution degree is increased.

There is no particular limitation on the method of impregnating the composite sheet containing cellulose with the aqueous reaction solution, but the composite sheet is immersed in an excess amount of the reaction solution and then squeezed by a roll to remove the excess reaction solution. Alternatively, a previously calculated amount of the reaction solution may be applied by a coater. The sheet containing the aqueous reaction solution is heated by blowing air under a temperature condition of 50 to 150 ° C. to evaporate and remove a part of the water of the aqueous reaction solution contained in the sheet. The content of water is adjusted to be a value within the range of 20 to 60% by weight and at least 5% by weight lower than the rate of water before heating. The method of evaporating is not particularly limited, but a method of evaporating water in the shortest possible time is desirable.

Since the reaction rate of carboxyalkylation is considerably high, the evaporation temperature is too long even in the above temperature range.
For example, after 30 minutes or more, carboxyalkylation progresses or ends during evaporation, and the effect of the present invention cannot be obtained. Carboxyalkylation hardly progresses under the above-mentioned evaporation conditions (substitution degree is 0.1 or less), and such evaporation is performed in a dryer or in a reaction vessel while applying hot air in the temperature range described above. The method of evaporating is simple. In that case, if the proportion of water in the aqueous reaction liquid contained in the sheet after evaporation of water is less than 20% by weight, the degree of substitution will be sharply reduced, and the resulting water-absorbent sheet will be significantly It turns yellow and must be avoided. Further, when the proportion of water is higher than 60% by weight, the effect of imparting water absorption may be reduced. Immediately after adjusting the proportion of water in the aqueous reaction solution in this way, as described above, since almost no carboxyalkylation has occurred yet, by heating the composite sheet thereafter, the reaction of carboxyalkylation and crosslinking occurs. To perform. In this case, even if water evaporates during heating and escapes to the outside of the system, the proportion of water in the aqueous reaction solution needs to be maintained within the above range.

This operation is carried out by continuously passing the sheet containing the aqueous reaction liquid in which the proportion of water is adjusted, through the heating device, or by covering the sheet with a liquid-impermeable sheet to make the sheet hermetically sealed, and then the batch. In the formula, the reaction temperature can be easily heated by heating in the range of 50 to 110 ° C. Reaction temperature is 50
If the reaction temperature is lower than ℃, it takes a long time to complete the reaction. On the contrary, if the reaction temperature is higher than 110 ℃, the degree of substitution and water absorption of the resulting water-absorbent sheet tend to be low.
Moreover, the water-absorbent sheet is not suitable because it often turns yellow significantly. The heating may be performed from the outside of the sheet containing the aqueous reaction solution, but when the amount of the sheet is large, the temperature range may naturally reach due to the reaction heat of carboxyalkylation. Alternatively, the object may be achieved only by leaving it under a closed condition or under an open condition. The reaction time cannot be determined regardless of the reaction temperature, but is in the range of 10 minutes to 4 hours. If the reaction time is less than 10 minutes, the reaction will not be completed sufficiently even if the temperature is increased.
Since the reaction is completed even if the reaction time is longer than the time, it is meaningless to spend more reaction time.

[0021] As described above, the pure water absorption of the pulp fiber having the cross-linking bond and the carboxyalkyl group is mainly determined by the substitution degree of the carboxyalkyl group and the cross-linking density. The pure water absorption is theoretically higher as the substitution degree of the carboxyalkyl group is higher, but the substitution degree is practically 0.
35 to 0.8 is suitable. The upper limit of the degree of substitution is about 1.2, and even if the degree of substitution exceeds 1.2, the water absorption amount is almost saturated.
This is disadvantageous because the reaction cannot be achieved unless the reaction is repeated at least twice and the process becomes complicated and the cost of the resulting water-absorbent sheet increases. On the other hand, the degree of substitution is 0.
If it is less than 35, a sufficient amount of absorbed pure water cannot be obtained, but in consideration of fixing a cationic antibacterial substance to a part of carboxyalkyl groups, the substitution degree of carboxyalkyl groups is preferably 0.4 or more. The degree of substitution within the scope of the present invention described above is the total amount of the carboxyalkylating agent and the alkali metal hydroxide added to cellulose, the proportion of water in the aqueous reaction solution after evaporation of water, the reaction temperature, the reaction time, and the like. It is determined by the effect, and if necessary, these factors are appropriately selected, combined and adjusted to obtain a suitable degree of substitution.

On the other hand, the water absorption of pure water increases as the crosslink density decreases, but if it is too small, the gel strength becomes weak when water is absorbed, and the water-soluble carboxyalkylcellulose salt remains, giving a sticky feeling. Absent. On the contrary, if the crosslink density is too high, the amount of water absorption decreases, so it is necessary to set the optimum crosslink density depending on the application. In the present invention, the crosslinking density is adjusted by adjusting the addition rate of the crosslinking agent. The composite sheet that has undergone the carboxyalkylation and the crosslinking reaction contains a large amount of inorganic salts and decomposition products of the carboxyalkylating agent, and therefore it is necessary to remove and purify them, but any known method can be used. May be. For example, a method of removing impurities by washing with a mixture of water and an organic solvent compatible with water such as lower aliphatic alcohols such as methanol, ethanol and isopropyl alcohol can be preferably used.

For imparting the antibacterial property for the present invention, immobilization of quaternary ammonium salt, heavy metal ion and the like utilizing the ion exchange ability of carboxyalkyl cellulose salt is preferably used. As the quaternary ammonium salt which is an antibacterial component, all that has an antibacterial property can be used, and benzalkonium, benzethonium, dodecyltrimethylammonium and the like are particularly preferable. Examples of heavy metals include silver, copper, zinc, etc., and they are appropriately selected and used from these. Among the heavy metals, mercury has the strongest bactericidal effect, but it is extremely harmful to the human body and is not suitable as the antibacterial component of the present invention. For the above reasons, at least one selected from aqueous solutions of quaternary ammonium salts such as benzalkonium chloride and heavy metals such as silver nitrate, cupric chloride and zinc sulfate is compatible with water as described above. By making a mixed solution with a certain organic solvent and impregnating the obtained composite sheet therein, ion exchange occurs in the aqueous solution, and antibacterial property can be imparted to the composite sheet.

The content of the above-mentioned cationic antibacterial substance in the composite sheet is appropriately selected depending on the kind of the cationic antibacterial substance to be fixed or the intended use, but even if it is increased more than necessary, the antibacterial performance is saturated. In addition, the water absorption performance is sacrificed and deteriorates. Therefore, it is preferable that the amount is appropriately set within the range of 0.05 to 1.0% by weight based on the absolute dry weight of the composite sheet in consideration of the use and the like. The antibacterial water-absorbent sheet obtained as described above has excellent antibacterial performance and high liquid water absorption performance, and can maintain a sheet-like form even after absorbing liquid. Therefore, in disposable diapers, sanitary materials such as sanitary products, soil water retention agents, agricultural material fields such as nursery sheets, food freshness retention materials, food fields such as dehydration materials, and building material fields such as dew condensation prevention sheets for buildings. It is preferably used in a wide range.

[0025]

[Examples] The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. In the examples and comparative examples, all percentages indicate% by weight.

Example 1 A long fiber non-woven fabric was prepared in which polypropylene long fibers were accumulated and which had a large number of spot-fused areas in which the polypropylene long fibers were self-fused to each other. The fineness of the long fibers constituting this long-fiber nonwoven fabric was 2.5 denier, and the basis weight of the long-fiber nonwoven fabric was 15 g / m ² . Next, bleached softwood kraft pulp fiber (NBKP) was used without beating,
Wet papermaking without adding papermaking chemicals to produce paper sheets,
The obtained paper sheet was laminated on the surface of the long fiber non-woven fabric to form a laminate. This paper sheet is JIS P 81
The basis weight measured by the method shown in No. 24 was 80 g / m ² , and the density measured by the method shown in JIS P 8118 was 0.50 g / cm 3.

Then, the laminated body is placed on a transfer conveyor formed of a wire mesh with the paper sheet on the upper side and the long fiber non-woven fabric on the lower side.
Using a water jet jet device in which nozzle holes having a hole diameter of 0.1 mm are arranged at intervals of 0.6 mm, the water jet stream is jetted at a water pressure of 50 kg / cm ² while transferring at a speed of / min. A water jet stream was applied so as to penetrate from the surface of the sheet to the nonwoven fabric side, and then dried with a dryer at 120 ° C. As described above, the pulp fibers forming the paper sheet and the long fibers forming the long fiber nonwoven fabric were entangled with each other to obtain an integrated composite sheet.

This composite sheet was prepared by cutting it to a size of 20 cm × 30 cm, and this sheet was prepared using sodium hydroxide 8.38% and sodium monochloroacetate 24.4.
0%, ethylene glycol diglycidyl ether 0.6
After soaking in an aqueous reaction solution consisting of 8% and 66.54% water for 1 minute, taken out, sandwiched between filter papers and pressed, 3.0 g reaction solution (carboxyalkyl / glucose residue) per 1 g of the absolutely dry composite sheet. = 1.3 mol / mol). Then, a thermoelectric hot air dryer equipped with an exhaust facility was kept at 50 ° C., and while exhausting, the composite sheet containing the impregnating liquid was put in this dryer for 5 minutes to evaporate water. The ratio of water in the aqueous reaction solution contained in the composite sheet was 35%.

This composite sheet was put in a polyethylene bag, put in a dryer kept at 50 ° C. for 3 hours to carry out carboxymethylation and crosslinking of pulp fibers, and then taken out to obtain 70% of this composite sheet. The operation of immersing in a methanol aqueous solution, taking it out, sandwiching it between filter papers and pressing it was repeated 4 times to thoroughly wash the composite sheet. Then, the composite sheet is immersed in a mixed solution of a silver nitrate aqueous solution having a solid content concentration of 5% and methanol (methanol concentration 70%), taken out, sandwiched between filter papers and pressed, and finally the composite sheet is made up to 100%. It was immersed in methanol, taken out, sandwiched between filter papers, pressed, and then air-dried to obtain an antibacterial water-absorbent sheet. The content of silver contained in the composite sheet was 0.5% based on the total dry weight of the composite sheet.

The degree of substitution, the amount of pure water absorbed, and the antibacterial property of the resulting water absorbent sheet were tested by the following methods. Test method (1) A test sample having a degree of substitution of 1 g was placed in a flask, and 50 ml of a methanol-hydrochloric acid solution (a mixed aqueous solution prepared by dissolving hydrogen chloride in a 70% aqueous methanol solution to a concentration of 1 mol / liter).
Was added, the mixture was allowed to stand for 1 hour, washed thoroughly with methanol to completely remove hydrochloric acid, and air-dried. Next, the air-dried sample was placed in a 300 ml Erlenmeyer flask, about 30 ml of 0.1N sodium hydroxide solution and 100 ml of pure water were added, and the mixture was slowly stirred for 1 hour, and then phenolphthalein was added with 0.1N hydrochloric acid solution. Was used as an indicator, and the substitution degree was calculated by the formulas (1) and (2). Y = 0.1A-0.1B (1) Substitution degree = 162Y / (1000W-80Y) (2) However, A: Amount of 0.1N sodium hydroxide solution (ml) B: 0.1N of hydrochloric acid Amount (ml) Y: Amount of carboxymethyl group (milliequivalent) W: Weight of carboxymethyl cellulose (g)

[0031](2) Pure water absorption Cut the test sample into a size of 10 cm × 10 cm, and cut it into 25
Enclose in a mesh bag made of 0 mesh nylon and exchange this
1 in pure water obtained by distilling water deionized through resin
Soak for 0 minutes to absorb water, then pull it up and hang it
Down, drain the water for 10 minutes, and then weigh the test sample.
Measure and measure one absolutely dried test sample (0.01m ²) Per suck
The amount of absorbed water was indicated by the weight (g) of pure water collected.

(3) Two types of antibacterial test strains were used: Klebsiella pneumoniae and Staphylococcus aureus, which are often used for testing textile products. As a medium, a normal broth medium was used for the pre-culture, and a normal agar medium was used for the main culture. The composition of each medium is as shown below. Normal broth medium Normal agar medium Meat extract 5g Meat extract 5g Peptone 10g Peptone 10g Sodium chloride 5g Sodium chloride 5g Distilled water 1000ml Agar 15g pH 7.0 Distilled water 1000ml pH 7.0

As the procedure, first, the test strain was precultured in a normal broth medium at 37 ° C. for 24 hours, and the culture solution was diluted 1,000 times with high-pressure steam sterilized physiological saline (0.85% NaCl). This was used as a test bacterial solution. Then, 20 μl of the test bacterial solution was dropped on a 5 × 5 cm test piece, spread over the entire surface of the paper with a sterilized conradi stick, and left in a 37 ° C. incubator for 30 minutes. Next, attach the fungus inoculated surface of the test piece to a plate medium of ordinary agar prepared in advance, and further,
It was pressed against the culture surface with a sterilized Conradi stick. After removing the test piece, it was cultured for one day in a 37 ° C. incubator, and the antibacterial property was evaluated by the presence or absence of bacterial growth. What the bacteria propagated ×
What was not done was marked as ○.

Example 2 Antibacterial activity was the same as in Example 1 except that the ion exchange reaction was carried out using a mixed solution of benzalkonium chloride aqueous solution having a solid content of 3% and methanol (methanol concentration of 65%). A water absorbent sheet was obtained. The content of benzalkonium contained in the composite sheet was 0.1% based on the total dry weight of the composite sheet. The composite sheet thus obtained was used in Example 1.
Tested and evaluated in the same manner as.

Comparative Example 1 A composite sheet in which the long fiber nonwoven fabric obtained in Example 1 and pulp fibers are entangled and integrated, that is, a composite sheet in which carboxymethylation of pulp fibers and fixation of a cationic antibacterial substance are not carried out. Was tested and evaluated in the same manner as in Example 1.

Comparative Example 2 The crosslinked carboxymethylated composite sheet obtained in Example 1, that is, the water-absorbent composite sheet not impregnated with the mixed solution of the aqueous silver nitrate solution and methanol was prepared in the same manner as in Example 1. Tested and evaluated.

The results obtained in the examples and comparative examples are shown in Table 1.

[0038]

[Table 1]

As can be seen from Table 1, the composite sheet of the present invention has a high degree of substitution, excellent antibacterial performance, and extremely excellent pure water absorption (Examples 1 and 2). On the other hand, the composite sheet that does not undergo the crosslinking reaction and carboxymethylation has a low water absorption of pure water and no antibacterial property (Comparative Example 1).
The composite sheet on which the cationic antibacterial substance is not fixed has a high pure water absorption, but does not have antibacterial performance (Comparative Example 2).

[0040]

The present invention has the effect of providing a sheet having both excellent water absorption performance and antibacterial performance.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location A01N 59/20 A01N 59/20 Z A61F 13/15 D06M 15/55 D06M 15/55 A61F 13/18 B

Claims (1)

[Claims] 1. An antibacterial water-absorbing sheet comprising a composite sheet containing synthetic fibers and a pulp fiber having a crosslinked carboxyalkyl group, wherein a cationic antibacterial substance is fixed to a part of the carboxyalkyl group by ion exchange. An antibacterial water-absorbent sheet characterized by being added.