JPH0284957A - Water absorptive material - Google Patents

Abstract

PURPOSE:To enhance the safety to the human body, to prevent the growth of microorganisms and to obtain stable water absorptivity by adding and compounding antibacterial zeolite which is formed by substituting a part or the whole of the ion exchangeable ions in antibacterial zeolite with antibacterial metal ions into and with a water absorptive resin. CONSTITUTION:The antibacterial zeolite is formed by bringing zeolite into contact with an aq. soln. mixture contg. the previously prepd. antibacterial metal ions of silver, copper, zinc, etc., and more preferably contg. further polyvalent metal ions to substitute the exchangeable ions in the zeolite and the above- mentioned ions. The antibacterial metal ions are adequately incorporated at 0.1 to 20% into the zeolite. The antibacterial zeolite contg. 0.1 to 15% silver ions and 0.1 to 18% copper ions or Zinc ions is more preferable. The polyvalent metal ions are exemplified preferably the ions of aluminum, cobalt or barium. The water absorptive performance such as gel characteristics of the water absorptive resin are stabilized if the metal ions are incorporated at 0.1 to 10%, more preferably 0.2 to 2% into the zeolite. In addition, the stability to heat and pressure at the time of production is improved and the remaining of the unreacted monomer at the time of production is prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a water absorbent material that has antibacterial, antifungal, and antialgal properties without impairing its original water absorbency, and is highly safe for the human body. Specifically, the present invention relates to a water-absorbing material having antibacterial and antifungal properties, which is made by dispersing zeolite containing antibacterial metal ions.

[Prior art] Water-absorbing resins absorb water hundreds to thousand times their own weight, and hydrogels (I aqueous crosslinked polymers) that have swollen by absorbing water can withstand even some pressure. It is a resin with excellent gel strength that does not allow water to separate, and has water-retaining properties.In recent years, it has been used in sanitary products such as sanitary products and diapers, as well as agricultural and horticultural products such as water-retaining agents and soil conditioners. Among these products, hygiene-related products in particular use protective colloids during polymerization (JP-A No. 61-40309, JP-A No. 61-87702) in consideration of skin irritation since they come into direct contact with the human body.
No.), Japanese Patent Application Laid-open No. 61 (1986), which uses water-soluble and oil-soluble polymerization initiators to make it difficult to generate unreacted monomers.
-2713.03) is disclosed.

[Problem to be solved by the invention] Sanitary products, which have many uses as water-absorbing materials, need to be made more hygienic by not only ensuring the safety of the material itself, but also adding antibacterial properties. desirable. However, until now, most antibacterial agents have been organic substances.
Due to its toxicity, it is completely impossible to apply it to sanitary materials, and no such proposal has been made.

An object of the present invention is to provide a water-absorbing material made of a water-absorbing resin composition that solves such problems.

[Means for Solving the Problems] The present inventors have conducted intensive research on an antibacterial agent suitable for water-absorbing materials that is highly safe for the human body, prevents the growth of such microorganisms, and has stable water-absorbing properties. As a result, when antibacterial zeolite, in which some or all of the ion-exchangeable ions in zeolite are replaced with antibacterial metal ions, is added and blended into a water-absorbing resin, the above-mentioned problems of safety such as skin irritation and antibacterial problems can be improved. The inventors have completed the present invention by discovering that the composition satisfies all of the properties of anti-fungal properties, anti-mildew properties, anti-algae properties, and water absorption stability.

That is, the present invention provides a water-absorbing material made of a water-absorbing resin composition containing an antibacterial zeolite in which some or all of the ion-exchangeable ions in the zeolite are replaced with antibacterial metal ions. .

The present invention will be explained below.

In the present invention, the water-absorbing material is a water-absorbing resin composition with antibacterial properties obtained by the reaction of zeolite particles holding antibacterial metals, a polymerizable monomer, and a polymerization initiator. It can be manufactured directly on a base material such as resin or as a composite material.

An antibacterial zeolite in which part or all of the ion-exchangeable ions in the zeolite, which are essential components of the water-absorbing material of the present invention, are replaced with polyvalent metal ions and antibacterial metal ions will be described.

In the present invention, as the "zeolite", both natural zeolite and synthetic zeolite can be used.

Zeolite is generally an aluminosilicate with a three-dimensional skeleton structure, and has the general formula XMzznO.Alt.
Displayed as os ・YSiOt ・ZHtO. Here, M represents an ion that can be exchanged, and is usually a monovalent or divalent metal ion. n is the valence of the (metal) ion. X and Y represent the respective metal oxides, silica coefficients, and 2 represents the number of crystal water. Specific examples of zeolites include A-type zeolide, X-type zeolide, Y-type zeolide, T-type zeolide, high silica zeolite, sodalite, mordenite, analcyme,
Examples include clinoptilolite, chabasite, and erionite. However, the ion exchange capacity of these exemplary zeolites is not limited to A
-type zeolide 7meq/g, X-type zeolide 5.4
11eq/g, Y-type zeolide 5meq/g, T
-type zeolide 3.4 meq/gs sodalite 11.
5 meq/g, mordenite 2.6 seq/g, analcyme 5+eq/g-clinoptilolite 2.6 Il
leq/g, chabasite 5 meq/g - erionite 3.8 meq/g, and both have sufficient capacity for ion exchange with antibacterial metal ions.

The antibacterial zeolite used in the present invention includes ion exchangeable ions in the zeolite, such as sodium ions,
Part or all of calcium ions, potassium ions, magnesium ions, iron ions, etc., are replaced with antibacterial metal ions, preferably polyvalent metal ions and antibacterial metal ions. As examples of antimicrobial metal ions, mention may be made of ions of silver, copper, zinc, mercury, tin, lead, bismuth, cadmium, chromium or thallium, preferably ions of silver, copper or zinc.

From the viewpoint of antibacterial properties, it is appropriate that the antibacterial metal ions are contained in the zeolite in an amount of 0.1 to 15%.

Antibacterial zeolites containing 0.1-15% silver ions and 0.1-18% copper or zinc ions are more preferred, while polyvalent metal ions are present in the zeolite at 0.2-2%.
%, preferably 0.5 to 1%, from the viewpoint of improving the water absorption rate of the water absorbent material. In addition, in this specification, % means % by weight on a dry basis at 110°C.
means.

Examples of polyvalent metal ions include ions of alkaline earth metals such as aluminum, cobalt, manganese, iron, titanium, nickel and magnesium, calcium, strontium, barium, preferably aluminum, cobalt or barium ions. can. The above polyvalent metal ions are contained in the zeolite in an amount of 0.1 to 10%, preferably 0.
．． The content of 2 to 2% stabilizes the water absorption performance such as the gel properties of the water absorbent resin, improves the stability against heat and pressure during production, and leaves unreacted monomers during production. This is more appropriate than not.

The method for producing the antibacterial zeolite used in the present invention will be explained below. For example, the antibacterial zeolite used in the present invention can be obtained by contacting the zeolite with a mixed aqueous solution containing antibacterial metal ions such as silver ions, copper ions, zinc ions, etc., preferably further containing polyvalent metal ions, prepared in advance. The above ions are replaced with ion exchangeable ions. The contact can be carried out at 10 to 70°C, preferably 40 to 60°C, for 3 to 24 hours, preferably 10 to 24 hours, by a bunch method or a continuous method (for example, a column method).

The pH of the above mixed aqueous solution is 3 to 10. Preferably 5-7
It is appropriate to adjust the This adjustment is preferable because it can prevent silver oxides and the like from being deposited on the zeolite surface or in the pores, and each ion in the mixed aqueous solution is usually supplied as a salt.

For example, silver ions include silver nitrate, silver sulfate, silver perchlorate, silver acetate, diammine nitrate, diammine silver sulfate, etc., and copper ions include copper nitrate (■), copper sulfate, perchlorate steel, copper acetate, etc.
Zinc ion, such as potassium tetracyanosterate, can be used with zinc nitrate (
■), zinc sulfate, zinc perchlorate, zinc thiocyanate, zinc acetate, etc., mercury ion, mercury perchlorate, mercury nitrate, mercury acetate, etc., tin ion, silver nitrate, tin sulfate, bismuth ion, bismuth chloride. , bismuth iodide, etc. Cadmium ions include cadmium perchlorate, cadmium nitrate, cadmium sulfate, cadmium acetate, etc. Chromium ions include chromium perchlorate, chromium nitrate, chromium sulfate, 'fMM ammonium chromium, etc., thallium ions include, thallium perchlorate,
Thallium nitrate, thallium sulfate, thallium acetate, etc. Aluminum ions include aluminum perchlorate, aluminum nitrate, aluminum sulfate, ammonium aluminum sulfate, etc. Cobalt ions include cobalt perchlorate, cobalt nitrate, cobalt sulfate, cobalt acetate, cobalt thiocyanate. Iron ions include iron perchlorate, iron nitrate, iron sulfate, iron ammonium sulfate, etc. Titanium ions include titanium sulfate, etc.
Manganese ions include manganese perchlorate, manganese nitrate,
Manganese sulfate, manganese acetate, etc. Nickel ions include nickel perchlorate, nickel nitrate, nickel sulfate, nickel acetate, etc. Magnesium ions include magnesium perchlorate, magnesium nitrate, magnesium sulfate, magnesium acetate, magnesium fluorosilicate, etc. Calcium ions include calcium perchlorate, calcium nitrate, calcium sulfate, calcium acetate, calcium thiocyanate,
Calcium chromate, etc., strontium ions, strontium perchlorate, strontium nitrate, strontium sulfate, strontium acetate, etc., barium ions,
Barium perchlorate, barium nitrate, barium acetate, etc. can be used.

The content of silver ions, etc. in the zeolite can be appropriately controlled by adjusting the tM degree of each ion (salt) in the mixed aqueous solution6. For example, when the antibacterial zeolite contains aluminum ions and silver ions, The aluminum ion concentration in the mixed aqueous solution is 0.1 M/j!
~0.8M/Il, silver ion concentration 0.002M/
j! '~0.15M/1, as appropriate.
Antibacterial zeolite having an aluminum ion content of 0.2 to 2% and a silver ion content of 0.1 to 5% can be obtained. In addition, when the antibacterial zeolite further contains copper ions and zinc ions, the copper ion concentration in the mixed aqueous solution is 0.
．． 1M/j! ~2.3M/1, zinc ion concentration is 0.
By setting it as 15M/1 to 2.8M/J, the copper ion content is 0.1 to 18% and the zinc ion content is 0.
．． 1-18% antibacterial zeolite can be obtained.

In the present invention, in addition to the mixed aqueous solution as described above, ion exchange can also be performed by using an aqueous solution containing each ion individually and bringing each aqueous solution into contact with the zeolite sequentially. The concentration of each ion in each aqueous solution can be determined according to the concentration of each ion in the mixed aqueous solution.

After ion exchange, the zeolite is thoroughly washed with water and then dried. Drying is preferably carried out at 105°C to 115°C under normal pressure or at 70°C to 90°C under reduced pressure (1 to 30 torr).

For ion exchange of ions without suitable water-soluble salts such as lead and bismuth, the reaction can be carried out using a linear solvent solution such as alcohol or acetone so that hardly soluble basic salts are precipitated.

In addition, the antibacterial zeolite used in the present invention has a moisture content of 0.5 to 30%, preferably 5 to 20%.
This is preferable from the viewpoint of obtaining a water absorbent resin composition having good dispersibility. Further, there is no particular restriction on the particle size of the antibacterial zeolite, but from the viewpoint of obtaining a more stable antibacterial effect, the particle size is preferably relatively small.The particle size of the powder is, for example, 0.04 to 20 μm. , preferably 0
．． It can be between 5 and 2μ.

The amount of antibacterial zeolite added in the water absorbent resin composition is 0.
05-20%, preferably 0.1-8%.

If the amount of antibacterial zeolite added is less than 0.05%, antibacterial
Antifungal effect decreases. On the other hand, even if the amount added exceeds 20%, the antibacterial and antifungal effects remain the same.

In the present invention, any polymerizable monomer can be used as long as it is a polymerizable unsaturated group-containing monomer having a carboxyl group or a carboxylate group as a functional group. Specifically, acrylic acid, methacrylic acid, itaconic acid,
Examples include maleic acid, fumaric acid and its salts, lower alkyl or lower alkoxy esters of dicarboxylic acids, acrylamide, vinyl sulfonic acid, acrylic acid methyl ester, acrylic acid ethyl ester, acrylic acid hydroxyethyl ester, polyethylene glycol monoacrylate, etc. Ru. All of these have a concentration of 20 to 60% by weight as an aqueous solution, preferably 30 to 40% by weight.
% and subjected to polymerization reaction.

In the present invention, the polymerization initiator includes commonly used water-soluble radical polymerization initiators such as potassium persulfate, ammonium persulfate, sodium persulfate, t-butyl hydroperoxide, cumene hydroperoxide, and hydrogen sulfite. Redox initiators in combination with reducing agents such as sodium, 1-ascorbic acid, ferrous salts, oil-soluble radical polymerization initiators such as benzoyl peroxide, diacyl peroxide such as lauroyl peroxide, azobisisobutyro Any azo compound such as a nitrile can be used, as well as mixtures thereof.

The polymerization initiator is 0.0 parts by weight per 100 parts by weight of the polymerizable monomer.
It is preferable to add 1 to 10 parts by weight to carry out the polymerization reaction.

In the polymerization reaction, a polymerization initiator was added to a homogeneous mixture of an aqueous solution of a polymerizable monomer and an aqueous suspension of antibacterial zeolite at an addition rate of 0.5 to 2 ml/min by spraying, etc., and the polymerization temperature was set at 4.
It is carried out at 0°C or lower, preferably 5 to 25°C, for 15 to 300 minutes.

In the polymerization reaction, t is determined by the conventionally known reverse phase suspension polymerization method, reverse phase emulsion polymerization method, and shear stress reaction method (JP-A-6
1-243805) can be applied. Furthermore, crosslinking agents, protective colloids, dispersants, colorants, foaming agents, fillers, extenders, antioxidants, fertilizers, fragrances, and other compounding agents may be added as necessary.

Methods for applying the water-absorbing resin composition obtained by polymerization reaction to a substrate include printing, slicing [kiss coating, roller coating, impregnation, and pouring through a nozzle (Flowins).
), bath treatment, foam treatment, etc., but a spraying method is preferred from the viewpoint of controlling the amount of resin composition to be used and ease of drying.

Furthermore, the water-absorbing resin can be applied in a pattern if necessary. Applicable substrates include short fibers, long fibers, webs, paper sheets, nonwoven fabrics, yarns (monofilament, multifilament, stable), knitted fabrics, knitted fabrics, loosely formed pads, and other porous shapes with a large surface area. is preferred.

As for the base material, cellulose-based materials such as wood pulp, rayon, and cotton, or polyester and polyacrylic materials are preferred from the viewpoint of high absorbency, but base materials molded from other synthetic resins, natural resins, rubber, etc. can also be used. You may.

In the water-absorbing material according to the present invention, a material to which the above water-absorbing resin composition is applied can also be used as one of the composite materials.

The water-absorbing material according to the present invention has a low residual unreacted monomer and is highly effective against microorganisms, and is suitable for use in sanitary products that come in direct contact with the human body, such as sanitary napkins, tampons, sanitary cotton, etc.
Suitable for disposable diapers, portable toilets, patient sheets, breast pads, incontinence products, etc. In addition, due to its excellent gel properties when absorbing water, it is used in various agricultural and horticultural products such as soil conditioners, seedling raising materials, agricultural films, water stop agents, anti-condensation agents, concrete planting mats, sealing materials, banking, and gas get. ,
Industrial materials such as sealants, putties, paints, poultices, poultices, aromatic base materials, chemical warmers, cosmetics, deodorants,
Suitable for household products such as desiccants, towels, cold packs, and toys.

The water-absorbing material obtained by the present invention can be similarly used in various fields in which conventional water-absorbing materials made of this type of water-absorbing resin are used, and can be used particularly effectively because it has the above-mentioned properties. .

[Effects of the Invention] The main features and advantages of the water-absorbing material of the present invention are summarized as follows.

(al) It maintains an excellent antibacterial effect against microorganisms such as bacteria, fungi, and algae over a long period of time.

佽) It is non-toxic and non-irritating to human skin, and is virtually harmless.

(C) Stable against heat and pressure during manufacturing and molding.

+d+ Water absorption performance is stable and gel properties upon water absorption are excellent.

(8) There is almost no unreacted monomer during the production of the water-absorbing resin, and there is no odor or discoloration due to it.

[Example] Next, embodiments of the present invention will be described with reference to Examples, but the present invention is not limited to the Examples.

Reference example (preparation of antibacterial zeolite) Zeolite is commercially available A-type zeolide (NazO・Al
zO* 2.05iOt 'XHzO: Average particle size 1
．． 1 μm), Y-type zeolide (NaiO'A1tOi
'4.03iOz ・XHtO: Average particle size 0.
6 μm) and 3J of natural clinoptilolite (150 to 250 mesh) were used. AgN0. as a salt to provide each ion for ion exchange. , Cu(NO
s)t, Zn(NOs)z, AI(NOz)*, Co
501F e (N Oi ) s, Ti(SO*)z
, MnSO4, N1(NOz)z, Mg(NOs)t
, Ba(NOs)t were used.

Table 1 shows the type of zeolite used in preparing each sample and the type and concentration of salt contained in the mixed aqueous solution. No,
Samples of 15 types of antibacterial zeolite, No. 1" and No. 15, were obtained.

For each sample, 1 kg of zeolite powder was heated and dried at 110°C, suspended in 1j+ water, and added with 0.5 kg of zeolite powder.
05N nitric acid aqueous solution was added dropwise at a dropping rate of 100 ml/30 minutes to adjust the pH to a predetermined value (5 to 7). Next, a mixed aqueous solution 31 of antibacterial metal salts at a predetermined concentration was added to the slurry for ion exchange. This reaction takes place from room temperature to 60°C.
Equilibrium was reached by stirring for 10-24 hours at <RTIgt;C.

After the ion exchange was completed, the zeolite powder was filtered and washed with room temperature water or hot water until excess silver ions in the zeolite phase disappeared. The sample was then heat dried at 110'C and
I got different kinds of samples. Zeolite used and obtained No. 1 to 15 antibacterial zeolite Examples (manufacture of water absorbing material) 500 m equipped with a stirrer, reflux condenser, and nitrogen gas inlet pipe
1 83g of lithium acrylate and 5g of water in a four-bottle flask
4.7 g and 17 g of acrylamide were added and dissolved. Take a predetermined amount (weight percent based on resin solid content) of the antibacterial zeolite prepared in Reference Example 1, and add 25% of water to it.
s 1 and the suspended slurry were mixed with a homogenizer until uniform.

After introducing nitrogen gas into the flask and expelling dissolved oxygen,
While cooling with water, 56.1 g of 95% potassium hydroxide was gradually added for neutralization. Neutralization was set at 75%.

A polymerization reaction was carried out by dropping 0.4% ammonium persulfate aqueous solution 501 as a radical polymerization initiator at a dropping rate of 1 ml/min at 20° C. for 50 minutes.

Polyester nonwoven fabric (Asahi Kasei IL-E1030) 5
0.3 g of the above-mentioned water-absorbing resin composition was sprayed onto G and dried under reduced pressure to obtain a water-absorbing material. A water absorbent material (Table 2, Comparative Example 1) not containing antibacterial zeolite was also obtained under similar conditions. Table 2 shows antibacterial zeolite and its added amount.

Test Example 1 (Antibacterial Test) The water-absorbing material prepared in the example was cut into 50 x 50 fl pieces, and 15 ml of Escherichia coli solution (105 pieces/ml) and Pseudomonas aeruginosa solution (10 S pieces/ml) were poured onto each piece, and 37 The cells were cultured at ℃ for 18 hours. The bacterial solution was washed away with physiological saline, and the number of E. coli bacteria present in this solution was determined from the above table. It can be seen that it has a sexual nature.

Test Example 2 (Water Absorption Test) The water absorption amount, water absorption rate, and gel strength after water absorption of the water absorbent material obtained in the above example were measured by the following methods. The results are shown in Table-3.

(Water absorption) Add 150 g of deionized water and 0.1 g of water-absorbing material to a 200 ml beaker, let it stand for 30 minutes, filter it through a 200 mesh metal mesh, measure the weight of the water flowing out, and The amount of water absorbed was determined by a formula.

(Water absorption rate) Evaluation was made based on the time required for 1 g of the water absorbent material to absorb 30 ml of physiological saline (0.9% aqueous sodium chloride solution).

(Gel Strength) 30 g of physiological saline was absorbed into 1 g of the water-absorbing material, and the surface hardness after gel formation was measured.

In each of the above water absorption tests, the water absorption stability of the water absorbent material was as follows: water absorption amount is 70 g/g or more, water absorption rate is 150 seconds or less, preferably 100 seconds or less, and gel strength is 3 x 10'dyne.
sec/aj or more, preferably 5 X10'dyne
- sec/- or more is appropriate for producing a practical water-absorbing material.

Table 3 From the table above, the water absorbent material of the present invention shows no decrease in water absorption stability such as water absorption amount, water absorption rate, gel strength, etc. compared to the conventional water absorbent material (Comparative Example 112), and also causes skin irritation. It turns out that there is no gender. Moreover, the one containing polyvalent metal ions (Example 4) has even better performance in terms of water absorption rate and gel strength.

Test Example 3 (Skin irritation test) A 1% ethanol solution of butyl roseoxybenzoate, which is used as an antibacterial agent for cosmetics, was added to the water-absorbing material obtained in the example and the material that did not contain the antibacterial zeolite obtained in Comparative Example 1. After adsorbing 20ml, the product was dried under reduced pressure to volatilize only ethanol (Table 3, Comparative Example-2), and a rabbit skin irritation test was conducted.

For 10 rabbit specimens, the area near the midline of the rabbit's back was shaved with electric clippers the day before application, and 3 application areas with an area of 25 x 25 ta were set up.Using a syringe needle, a wound was made in the dermis just before the start of application. Each of the water-absorbing materials (10 x 20 m) was pasted on the skin from which the stratum corneum had been peeled off by making a cross-shaped wound to the extent that it would not bleed or cause bleeding, and was fixed with adhesive tape so that it would not move back.

The application time was 24 hours, and after the application was completed, the adhesive tape and water-absorbing material were removed, and the remaining test substance adhering to the rabbit's skin was removed using water-soaked absorbent cotton. Skin irritation was evaluated based on the number of specimens in which red spots occurred in each specimen. The results are shown in Table-3.

Test Example 4 The processing pressure during production (drying under reduced pressure) of Examples and Comparative Example 1, the degree of resin crosslinking under heating conditions, the degree of coloring, and the odor of unreacted monomers were measured by the following methods. The results are shown in Table 4.

(Heat pressure resistance test) A sample immediately after production was processed in a vacuum dryer at 200°C and a gauge pressure of 10 torr for 30 minutes, and the color difference (ΔE) with the untreated sample was measured using a colorimeter (Minolta CR-100). was measured. Here, the value of ΔE is 3.0
If it is less than that, it is determined that the color has hardly changed.

(Amount of unreacted monomer) 1 g of the sample immediately after production was swollen in ether 50I111, and the supernatant liquid was analyzed for unreacted monomer using a gas chromatograph, and the amount was calculated as a weight percentage with respect to the sample.

(Light resistance test) A sample immediately after production was exposed to sunlight for 7 days, and the color difference from the unexposed sample was measured in the same manner as the heat and pressure resistance test.

Table 4 From the above table, the water-absorbing material of the present invention has excellent heat resistance and pressure performance during its production, and is less affected by coloring and the like. Furthermore, it can be seen that the amount of unreacted monomer is extremely small, and therefore the stability against light is also excellent.

Claims (4)

[Claims] 1. A water-absorbing material containing zeolite that retains antibacterial metals. 2. 2. The water-absorbing material according to claim 1, wherein the zeolite holding an antibacterial metal is an antibacterial zeolite in which some or all of the ion-exchangeable ions in the zeolite are replaced with polyvalent metal ions and antibacterial metal ions. 3. 3. The water-absorbing material according to claim 2, wherein the polyvalent metal ion is one or more metal ions selected from the group consisting of aluminum, cobalt, manganese, titanium, iron, nickel, and alkaline earth metals. 4. The water-absorbing material according to claim 1 or 2, wherein the content of zeolite retaining antibacterial metal ions is 0.05 to 20% by weight.