JP2734852B2 - Water absorbent resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antibacterial water-absorbing resin containing a specific phosphate compound having an antibacterial, antifungal and antialgal effect, and is particularly useful for infants, bedridden elderly people and sick people. Used for sanitary materials such as disposable diapers and sanitary napkins used for urination treatment, it can suppress the growth of harmful bacteria when in contact with the human body for a long time or after use, and can prevent odor. It is related to water-absorbent resin, and also to water-absorbent resin that can protect roots from pathogenic bacteria harmful to plants when added to soil as a water retention agent for agriculture, and is widely used in various industries. Things.

[0002]

2. Description of the Related Art Heretofore, there have been known inorganic antibacterial agents in which a metal having antibacterial properties such as silver and copper is supported on activated carbon, hydroxyapatite, zeolite and the like.
These are safer than organic antibacterial agents,
Since it does not cause volatilization and decomposition, it has a long lasting antibacterial effect and has excellent heat resistance. For this reason, attempts have been made to produce antibacterial paper by processing into various types of natural paper and synthetic paper, and the effect has been demonstrated. Also, a method has been proposed in which a water-soluble glass containing silver ions is supported on a water-absorbent resin, and antibacterial and deodorant properties are supported on the water-absorbent resin (Japanese Patent Laid-Open No. 1-153748).

However, antibacterial metals carried on inorganic antibacterial agents are often unstable, and those to which such inorganic antibacterial agents have been added undergo discoloration during or after processing.
It was unsuitable for making products with high commercial value from the appearance. In addition, since these inorganic antibacterial agents have a weak skeletal structure that holds the antibacterial metal and a weak power of holding stably, there is a problem that it is difficult to obtain a permanent antibacterial effect when used for a long time. . Furthermore, conventional antibacterial agents cannot be electrostatically adhered to fine substances or evenly adhered to surfaces when mixed and used in combination with various other substances due to the problem of their particle size, Dropping off after adhesion is a problem in many cases.

A method in which water glass containing monovalent silver ions is used together with a water-absorbing resin to elute silver ions when contacted with an absorbing solution has an excellent antibacterial effect, but has a relatively short time to develop the effect. In addition to having a poor permanent effect over time, the water-absorbent resin containing acrylic acid or the like as a main component has the problem that the presence of cations is a significant negative factor that impairs the water-absorbing ability.

[0005] Further, if nonwoven fabric or the like used for disposable diapers is replaced with antibacterial paper, the antibacterial agent comes into direct contact with the skin, and it suppresses even bacteria useful for the human body, which is not preferable.

[0006]

DISCLOSURE OF THE INVENTION The present invention has no discoloration over time, has an antibacterial, antifungal and antialgal effect permanently, and also has a high water absorbing ability which is an original property, It is intended to find a water-absorbing resin capable of preventing an appropriate antibacterial effect and offensive odor after disposal when used in disposable diapers and the like.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the water-absorbing resin containing a specific phosphate compound containing an antibacterial metal such as silver ion has been developed. The present inventors have found that the above problem has been solved, and have completed the present invention. That is, the present invention relates to a water-absorbing resin containing a phosphate represented by the following general formula [1] and having a network structure or a layered structure . M ¹ aAb M ² c (PO ₄ ) d · nH ² O [1] (M ¹ is silver, copper, zinc, tin, mercury, lead, iron, cobalt,
At least one l-valent metal ion selected from the group consisting of nickel, manganese, arsenic, antimony, bismuth, barium, cadmium and chromium, and A is an alkali metal ion, an alkaline earth metal ion, an ammonium ion and a hydrogen ion At least one type of m-valent ion selected from the group consisting of: M ² is a tetravalent metal;
n is a number satisfying 0 ≦ n ≦ 6, a and b are both positive numbers, la + mb = 1 or la + mb = 2, and c and d are c = 2, d = when la + mb = 1. 3, when la + mb = 2, c = 1 and d = 2. )

Hereinafter, the present invention will be described in detail. The compound used as an antibacterial agent in the present invention is an antibacterial phosphate represented by the general formula [1] and having a network structure or a layered structure. In the compound represented by the general formula [1] , when la + mb = 1, c = 2 and d = 3
A crystalline compound belonging to the space group R3c which have a respective coefficient of a compound in which each constituent ions make a three-dimensional network structure, when the la + mb = 2, the respective coefficients of c = 1, d = 2
Each constituent ions having is a compound for making a layered structure. As the phosphate in the present invention, la + mb = 1 and c = 2, since the phosphate can be easily obtained as fine particles and has little discoloration upon exposure to sunlight and excellent weather resistance.
A crystalline compound having a three-dimensional network structure where d = 3 is preferred.

M ¹ in the above general formula [1] is a metal known to exhibit both antibacterial and antifungal properties. Among them, silver has a remarkable antibacterial property in addition to safety. It is particularly effective and preferred as a metal that can be enhanced.

A in the above general formula [1] is an alkali metal ion, an alkaline earth metal ion, an ammonium ion or a hydrogen ion. Preferred examples of the alkali metal ion and the alkaline earth metal ion include lithium, sodium and the like. , Potassium, magnesium and calcium ions, among which lithium, sodium,
Ammonium ions and hydrogen ions are the preferred ions.

In the general formula [1], M ² is a tetravalent metal, and preferred specific examples include zirconium, titanium and tin, and zirconium is a particularly preferred metal in consideration of the safety of the compound.

The following are specific examples of the phosphate represented by the general formula [1]. Ag _0.005 Li _0.995 Zr ₂ (PO ₄ ) ₃ Ag _0.01 (NH ₄ ) _0.99 Zr ₂ (PO ₄ ) ₃ Ag _0.05 Na _0.95 Zr ₂ (PO ₄ ) ₃ Ag _0.2 K _0.8 Ti ₂ (PO ₄ ) ₃ Ag _0.1 H _0.9 Zr ₂ (PO ₄ ) ₃ and a part or all of Ag in each of the above formulas was changed to Zn, Mn, Ni, Pb, Hg, while maintaining the same charge amount as silver ions per mole of the compound. Compound substituted with Sn or Cu: Ag _0.001 Li _1.999 Zr (PO ₄ ) ₂ Ag _0.01 Na _1.99 Zr (PO ₄ ) ₂ Ag _0.01 K _1.99 Sn (PO ₄ ) ₂ · 1.2 H ₂ O Ag _0.1 (NH _{4 1.9} Ti (PO ₄ ) ₂ .4H ₂ O Ag _0.02 H _1.98 (PO ₄ ) ₂ .1.7 H ₂ O Some or all of Ag in the formula is Zn, Mn, Ni Pb, Hg, Sn, or compounds substituted with Cu,.

The method for synthesizing the phosphate in the present invention includes a calcination method, a wet method and a hydrothermal method, and can be easily obtained, for example, as follows. ○ Synthesis of network-structured phosphate When synthesized by the firing method, compounds containing alkali metals such as lithium carbonate (Li ₂ CO ₃ ) or sodium carbonate (Na ₂ CO ₃ ), zirconium oxide (ZrO ₂ ), etc. Compound containing zirconium and ammonium dihydrogen phosphate (NH ₄ H
A compound containing a phosphate group such as ₂ PO ₄ ) is mixed at a molar ratio of about 1: 4: 6, and calcined at 1100 to 1400 ° C. to obtain a compound represented by the general formula [2]. To obtain the desired compound. A _x Zr ₂ (PO ₄ ) ₃ [2] (A has the same meaning as described above, and x is 1 when A is monovalent, and is １ ／ when A is divalent.) The compound represented by the general formula [1] can be obtained by immersing the compound represented by the general formula [2] in an aqueous solution containing silver ions at an appropriate concentration at room temperature to 100 ° C.

In the case of synthesizing by a wet method, oxalic acid is added to an aqueous solution of zirconium oxynitrate and sodium nitrate while stirring, and further phosphoric acid is added thereto. The pH of the reaction solution was adjusted to 3.5 with an aqueous sodium hydroxide solution, and the mixture was heated under reflux for 78 hours. The precipitate was filtered, washed with water, dried, and dried.
Crushed and mesh zirconium phosphate [NaZr ₂ (P
O ₄ ) ₃ ]. By immersing this in an aqueous solution containing an antibacterial metal at an appropriate concentration, the compound represented by the general formula [1] can be obtained.

In the case of synthesizing by a hydrothermal method, for example, the synthesis may be performed as follows. Ammonium dihydrogen phosphate is slowly added to the aqueous solution of zirconium sulfate with stirring to form a precipitate. Then, the pH value of the reaction solution was adjusted to 2 with an aqueous solution of caustic soda, and in a closed container maintained at 130 ° C.
After heating the precipitate for 32 hours under saturated vapor pressure, the precipitate is filtered, washed with water, dried and pulverized to obtain crystalline zirconium phosphate NH ₄ Zr ₂ (PO ₄ ) ₃ . Further, this crystalline zirconium phosphate was added to an aqueous solution of silver nitrate having an appropriate concentration,
By stirring, an antibacterial phosphate Ag _X (NH ₄ ) _{1 -X} Zr ₂ (PO ₄ ) ₃ having an average particle size of 1 μm or less is obtained (x is 0).
-1. ).

Synthesis of a phosphate having a layered structure An oxychloride containing a zirconium such as zirconium oxychloride, titanium oxychloride or tin oxychloride, or a tetravalent metal such as titanium or tin in a concentrated aqueous solution of phosphoric acid. , And the mixture was heated under reflux for 24 hours, and the precipitate was filtered, washed with water, dried and pulverized, and zirconium phosphate [Zr (HPO
₄ ) A phosphate such as ₂ · H ₂ O] is obtained, and this is added to an aqueous solution of a nitrate such as an alkali metal, and stirred, washed with water, dried and pulverized to obtain a compound represented by the general formula [3]. . A _2x Zr (PO ₄ ) ₂ .nH ₂ O [3] (A, x and n have the same meanings as above.) The compound represented by the general formula [3] contains an antibacterial metal at an appropriate concentration. By immersing in an aqueous solution, the compound represented by the general formula [1] is obtained.

The value of a in the general formula [1] is determined by the concentration of silver in the aqueous solution in which the compound represented by the general formula [2] or [3] is immersed, and the value of the general formula [2] or [ By adjusting the time or temperature at which the compound represented by 3) is immersed, it can be appropriately adjusted according to the required properties and use conditions.

In order to exhibit antibacterial properties, it is better that the value of a in the general formula [1] is large. However, if the value of a is 0.001 or more, it is necessary to sufficiently exhibit antibacterial properties and antifungal properties. Can be. However, if the value of a is less than 0.001, it may be difficult to exhibit antibacterial properties for a long time, so the value of a is preferably 0.01 or more.
In consideration of economy, the value of a is suitably 0.5 or less.

The average particle size of the phosphate used in the present invention is as follows:
For uniform dispersion in the resin, the particle size is preferably 1 μm or less. By using a uniform and fine particle compound, it is easy to add the compound to the water-absorbent resin, and the surface of the particles of the water-absorbent resin is uniformly formed. It becomes possible to adhere, and the property as an antibacterial agent and the property of a water-absorbing resin can be effectively exhibited.

The above-mentioned phosphate is stable against exposure to heat and light, and its structure and composition do not change at all even when heated at 500 ° C. or higher, and sometimes at 800 ° C., and irradiation with ultraviolet light Does not cause any discoloration. Further, there is no change in the skeletal structure in contact with water in a liquid state or in an acidic solution. As described above, the phosphate compound used in the present invention is chemically and physically stable, and is not subject to restrictions such as acid resistance and light-shielding conditions during various processing and storage and furthermore during use.

These phosphates can be produced and used according to the method described above, but commercially available products (Novalon AG-30)
0: trade name / Toagosei Chemical Industry Co., Ltd.), which can also be used.

There is no particular limitation on the water-absorbing resin to which the above-mentioned phosphate is applied. By having a crystal structure or a cross-linked structure in the polymer, it absorbs and swells quickly when it comes into contact with water. Any polymer composed of a polymer having an ability can be used. Specifically, poly (meth) acrylate, polyvinyl alcohol, polyethylene oxide, polysulfonate, poly (meth) acrylamide, carboxymethylcellulose, vinyl alcohol / acrylate Copolymers, synthetic polymer compounds containing acrylate / acrylamide copolymer as a main component, and natural polymer such as agar, konjac mannan, alginic acid, carrageenan, and the like, in which the above synthetic polymer compound is grafted. The above-mentioned phosphate is added to these water-absorbing resins, and a water-absorbing resin having antibacterial properties is obtained. That. The water-absorbing resin may be a single resin or a mixture of two or more.
Can be.

The amount of the phosphate added to the water-absorbent resin is 0.000 with respect to the powder of the water-absorbent resin from the viewpoints of effect and economy.
It is preferably from 1 to 5%, more preferably from 0.05 to 2%. If the added amount of the phosphate is less than 0.0001%, the antibacterial effect is not sufficiently exhibited, and even if the added amount is more than 5%, the effect according to the ratio of addition is not observed, and there is an economic problem. In addition, it becomes slightly inferior to the case of the water-absorbing resin alone in terms of the water absorption speed of the water-absorbing resin and the feeling of salat,
Furthermore, there is a possibility that phosphate may fall off from the surface of the added water-absorbent resin. Also, depending on the surrounding conditions, when the amount of the added phosphate is less than about 0.5% based on the water-absorbent resin powder, the phosphate only prevents the growth of bacteria,
Above that, it has the effect of sterilizing and sterilizing surrounding bacteria.

As a method of adding a phosphate to the water-absorbing resin, various methods such as a method of joining by pressure, a method of bonding using a binder such as an adhesive, and a method of simply mixing can be considered. Although it can exert its effect, it is preferable to add it at the surface treatment stage of the water-absorbing resin as described below in consideration of economy, workability, quickness of the effect, and the like.

[0025] A small amount of water is added to the water-absorbing resin powder (the resin containing 3% or more of water can be used as it is in advance). Of the present invention and other additives as necessary are added and stirred well. At this time, it is possible to heat and dry at the same time as stirring, or to heat and dry after stirring.

A small amount of water, a polyfunctional crosslinking agent, the phosphate of the present invention, and other additives as necessary are added to the water-absorbent resin powder and heated with stirring. The polyfunctional crosslinking agent used in this case is a diglycidyl ether compound, a polyvalent metal salt, a haloepoxy compound, an aldehyde compound, a carboxylic acid group in a water-absorbing resin such as an isocyanate compound,
It is a crosslinking agent having two or more functional groups capable of reacting with a hydroxyl group, a sulfonic acid group, an amino group and the like.

[0027]

[Function] A specific phosphate compound containing an antibacterial metal such as silver ion is blended with a water-absorbing resin to impart an antibacterial property to the resin without impairing the properties of the water-absorbing resin. To play.

[0028]

EXAMPLES The present invention will be described below with reference to examples and evaluation tests in order to clarify the excellent effects of the water-absorbent resin of the present invention. Example 1 20 parts by weight of water was added to 100 parts by weight of a sodium acrylate-based water-absorbing resin powder having a water absorption capacity of about 300 times that of distilled water, and an antibacterial phosphate (Novalon AG-300: commercial product) was added with good stirring. (Manufactured by Toagosei Chemical Industry Co., Ltd.). Then at 120 ° C about 2
After drying for a time, the water-absorbent resin of the present invention was obtained. When the water-absorbing capacity of the resin was measured, it was about 300 times and almost no decrease in capacity was observed.

Example 2 30 parts by weight of water and 1 part by weight of an antibacterial phosphate (Novalon AG-30) were added to 100 parts by weight of a sodium acrylate-based water-absorbent resin powder having a water absorption capacity of about 300 times that of distilled water.
0: trade name / manufactured by Toagosei Chemical Industry Co., Ltd.) and 0.5 parts by weight of a polyethylene glycol diglycidyl ether-based compound, heated and stirred, and dried at 120 ° C. for about 2 hours to obtain a water-absorbent resin of the present invention. Was. When the water-absorbing capacity of the resin was measured, it was about 300 times and almost no decrease in capacity was observed.

Comparative Examples 1 and 2 To 100 parts by weight of a sodium acrylate-based water-absorbing resin powder having a water absorption capacity of about 300 times that of distilled water, 1 part by weight of water glass containing 30 parts by weight of water and silver ions was added. After mixing well, the mixture was dried and pulverized to obtain a water-absorbing resin having antibacterial properties (Comparative Example 1). When the water absorption capacity of the resin was measured, it was about 50 times lower. For comparison, a sodium acrylate-based water-absorbing resin (Comparative Example 2) having a water absorption capacity of about 300 times that of distilled water that had not been treated was used.

Evaluation Test 1 To 0.1 g of a sample, 10 ml of a bacterial solution containing 10 ⁶ cells / ml of E. coli strain prepared with sterilized water was added and allowed to swell. After culturing at 37 ° C. for 6 hours, a portion was placed on an agar medium, and the number of surviving bacteria after culturing for 18 hours was measured.

Evaluation Test 2 0.1 g of a sample was added to 10 ⁶ cells /
10 ml of the bacterial solution containing the E. coli strain was added to swell. 3
After culturing at 7 ° C. for 6 hours, the number of surviving bacteria was measured.

Evaluation Test 3 A bacterial solution obtained by culturing each strain of Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa for 4 hours in a nutrient broth medium was added to an agar medium at 0.5% (v / v). 10 ml was dispensed into a petri dish and solidified. Here, 0.1 g of the sample was added to 4 g of sterile physiological saline.
After swelling by adding ml, the culture was put on the plate and cultured for 18 hours, and the growth state of the strain around the sample was observed.

Evaluation Test 4 0.05 g of a sample was placed in 20 ml of sterile physiological saline to swell, 1 ml of a 10 ⁶ cells / ml Escherichia coli solution prepared with sterile physiological saline was added, and cultured with shaking. , 6, and 24 hours later, the number of viable bacteria was measured.

The results of the above evaluation tests are shown in Table 1. From these results, it is clear that the water-absorbent resin of the present invention has the original properties of water absorption and excellent antibacterial properties. It is. In the table, the symbol ○ indicates that the bacterium did not grow, and the mark × indicates that the bacterium grew.

[0036]

[Table 1]

[0037]

The water-absorbent resin of the present invention has excellent antibacterial properties due to the presence of a specific phosphate compound and is also excellent as a water-absorbent resin, so that urine can be discharged from infants, bedridden elderly people, sick persons, etc. It is used for sanitary materials such as disposable diapers and sanitary napkins used in the treatment of, and can prevent the growth of harmful bacteria when in contact with the human body for a long time, or after use, and prevent odors. Also, when added to soil as a water retention agent for agriculture, it has an excellent effect of protecting roots from pathogenic bacteria harmful to plants.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hideki Kato 1 East, Funami-cho, Minato-ku, Nagoya-shi, Aichi Pref. −38504 (JP, A)

Claims (1)

(57) [Claims] 1. A network-like structure represented by the following general formula [1]:
A water-absorbing resin comprising a phosphate having a layered structure . M ¹ aAb M ² c (PO ₄ ) d · nH ² O [1] (M ¹ is silver, copper, zinc, tin, mercury, lead, iron, cobalt,
At least one l-valent metal ion selected from the group consisting of nickel, manganese, arsenic, antimony, bismuth, barium, cadmium and chromium, and A is an alkali metal ion, an alkaline earth metal ion, an ammonium ion and a hydrogen ion At least one type of m-valent ion selected from the group consisting of: M ² is a tetravalent metal;
n is a number satisfying 0 ≦ n ≦ 6, a and b are both positive numbers, la + mb = 1 or la + mb = 2, and c and d are c = 2, d = when la + mb = 1. 3, when la + mb = 2, c = 1 and d = 2. )