JPH06293611A - Antimicrobial material - Google Patents

Abstract

PURPOSE:To obtain a new antimicrobial material using metallic ultrafine particles. CONSTITUTION:This antimicrobial material is capable of manifesting antimicrobial performance in an extremely small amount due to the ultrafine particles, having <200nm particle diameter and dispersed in a base material. A typical method for preparing this antimicrobial material is to contain a metallic salt, etc., in a polymer which is the base material, then reduce the metallic salt according to heat treatment and prepare the ultrafine particles in the polymeric raw material. Since the antimicrobial performance is manifested with a low metallic content, this antimicrobial material can be prepared at a low cost and the duration of the antimicrobial performance is long.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel organic polymer or inorganic material having antibacterial, antifungal and deodorant properties.

[0002]

2. Description of the Related Art Since microorganisms such as mold and bacteria adhere to fibers and plastics to cause slime and mold, in recent years, antibacterial / mold / deodorant demands have been increasing in various fields. Antibacterial properties are applied to socks, underwear, medical clothes, fibers such as masks, resins used around water such as baths and kitchen utensils, and films as packaging materials for foods. Efforts are being made to

Further, as antibacterial soil improvers and horticultural soil / turf soil improvers, antibacterial / mold / deodorant properties are required. In addition, molds and the like are generated in mortar and glass as building materials, and improvement thereof is required. Conventionally used antibacterial agents are roughly classified into two types. One is an organic antibacterial agent, which uses a silicon quaternary ammonium salt or the like. JP-A-57-51
Japanese Patent No. 874 discloses a carpet in which an organic silicon quaternary ammonium salt is adsorbed and a method for producing the carpet.

As a second method, it has long been known that silver ions, copper ions and zinc ions exhibit antibacterial properties, and metal compounds such as silver, copper and zinc are used as antibacterial agents. . For example, JP-A-54-147220 proposes a method of dispersing and mixing a metal compound such as silver, copper or zinc in a polymer to form a fiber. Furthermore,
A method for adding and mixing zeolite solid particles substituted with silver ions and copper ions to an organic polymer is disclosed in JP-A-59-13323.
No. 5, JP-A-60-181002, and the like. JP-A-3-7201 proposes silicon oxide as a metal ion carrier. In addition, "Antibacterial and antifungal agent using clay mineral as carrier" (Gypsum &
Lime No. 229 P.I. 267-274 (199
2)) also has a review article.

An antibacterial agent using fine metal particles has also been proposed. For example, Japanese Patent Laid-Open No. 169740/1990 discloses that cellulose fibers have an average particle size of 5 such as silver, copper or zinc.
An antibacterial fiber using metal fine particles having a size of μm or less has been proposed. Further, in JP-A-1-96244, a mixture of metallic copper fine particles having an average particle diameter of 5 μm or less and a polyester compound is prepared, and then this mixture is dispersed in a thermoplastic molded product having a melting point of 200 ° C. or more. It is disclosed that the molded article exhibits antibacterial properties.

However, the metal fine particles described in these patents all have a particle size of 0.2 μm or more,
Further, the content of the metal fine particles in the molded product is 0.1 to 1
It was a very large amount of 0% by weight. Since it is necessary to use a large amount of fine metal particles in order to exhibit sufficient antibacterial properties, a smaller amount of antibacterial properties is used to reduce problems during molding, ensure the quality of molded products, and reduce costs. There has been a demand for a material capable of expressing

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an antibacterial material having excellent antibacterial performance.

[0008]

The present invention is characterized in that ultrafine metal particles having an average particle size of less than 200 nm are dispersed in the base material in an amount of 0.1 ppm or more, and the antibacterial material and the ultrafine metal particles are silver. The above antibacterial material is an ultrafine particle containing at least one selected from copper, zinc, iron, mercury, lead, tin, bismuth, cadmium and chromium.

Any metal species may be used in the ultrafine metal particles of the present invention, but silver, copper, zinc, iron, mercury,
It is an ultrafine metal particle containing at least one metal species selected from tin, lead, bismuth, cadmium and chromium.
More preferred are ultrafine metal particles containing at least one metal species selected from silver, copper, zinc and iron. The surfaces of the ultrafine particles may be oxidized into oxides, hydroxides, halides and the like.

The average particle size was measured as follows. Using an ultramicrotome, the prepared antibacterial material was used to prepare an ultrathin section, and this section was placed on a copper grid to which a collodion support film was attached, and carbon vapor deposition was performed to obtain a sample for transmission electron microscope observation. did. Ultrathin section thickness is 5
It is 0 nm or more and 100 nm or less. Using a transmission electron microscope (JEM-4000FX, manufactured by JEOL Ltd.), an observation magnification of 50,000 times or 10 at an acceleration voltage of 200 kV.
Photographs were taken at a magnification of 200,000 and a magnification of 200,000 or 400,000. Next, using this photograph, the diameters of 100 adjacent ultrafine particles within a certain range in the photograph of the image analyzer were measured, and the arithmetic average thereof was taken as the average particle diameter. However, when the number of ultrafine particles was less than 100 in the photograph, the required number of transmission electron micrographs at different locations were used to make 100, and the average particle diameter was determined.

In the present invention, the average particle size of the ultrafine metal particles needs to be less than 200 nm, preferably 100 nm or less, more preferably 50 nm or less. When the particle size is 200 nm or more, the antibacterial performance is weak or there is no antibacterial property. I'm not sure why,
By using ultrafine particles of less than 200 nm, more remarkable antibacterial performance is observed.

As the base material in which the ultrafine metal particles are dispersed,
There can be mentioned various substances, but also polymer materials such as fibers, plastics, adhesives and films, and various inorganic materials such as clay and glass. Fibers include cotton, wool, silk, hemp, rayon fiber, cupra fiber, acetate fiber, vinylon fiber, nylon fiber, vinylidene fiber, polyvinyl chloride fiber, polyester fiber, polyethylene fiber, acrylic fiber, polypropylene fiber, and glass fiber, Inorganic fibers and the like can be mentioned.

As the resin, a thermoplastic resin, a thermosetting resin, a natural polymer or the like can be used. Specifically, as the thermoplastic resin, AAS resin, AES resin, AS
Resin, isophthalene-maleic anhydride copolymer resin, AB
S resin, ACS resin, ethylene-vinyl chloride copolymer resin, vinylidene chloride resin, vinyl chloride resin, coumarone resin, ketone resin, vinyl acetate resin, phenoxy resin, butadiene resin, fluororesin, polyacetal, polyamide, polyamideimide, polyarylate, poly Ether imide,
Polyether ether ketone, polyethylene, polyethylene terephthalate, polycarbonate, polystyrene, polysulfone, polyparamethylstyrene, polyvinyl alcohol, polyvinyl ether, polyvinyl butyral, polyvinyl formal, polyphenylene ether, polyphenylene sulfide, polypropylene, polymethylene pentene, methacrylic resin, liquid crystal polymer And so on. DFK as the thermosetting resin
Resin, epoxy resin, xylene resin, phenol resin,
Examples thereof include polyimide, polyurethane, melanin resin, urea resin, vinyl ester resin and unsaturated polyester resin. Further, cellulose derivatives such as methyl cellulose and ethyl cellulose, acetate plastics, cellulose acetate and the like can be mentioned.

The amount of ultrafine metal particles in the antibacterial material naturally varies depending on what is dispersed, and even if the content is large, the antibacterial property is naturally expressed, but the physical properties of the base material are not significantly deteriorated. Is usually less than 5000 ppm, and if less than 0.1 ppm, the antibacterial performance is not stable,
Moreover, since it is not remarkable, it is necessary to be 0.1 ppm or more. When dispersed in a polymer such as fiber or resin, it is preferably less than 1000 ppm, and more preferably 500 ppm or less and 0.5 ppm or more.

The method for producing ultrafine metal particles can be selected from a vapor phase method, a liquid phase method, a solid phase method and the like. Evaporation,
A method for producing ultrafine metal particles in vacuum such as a sputter or a laser ablation method, a method for producing ultrafine metal particles by reducing a metal salt in a solution containing an anticoagulant such as a surfactant, etc. Can be mentioned.
An antibacterial polymer material can be prepared by dispersing the metal fine particles thus prepared in a polymer. Further, it is also possible to use the antibacterial polymer material in which the produced high concentration ultrafine metal particles are dispersed as a masterbatch to produce the final concentration.

A solvent-soluble polymer, a metal salt, and a reducing agent are dissolved in a solvent to produce ultrafine metal particles by a reduction reaction.
After removing the solvent, a method of producing an antibacterial polymer material in which ultrafine metal particles are dispersed, or by dissolving or impregnating the metal salt alone or the metal salt and a reducing agent in the polymer, then performing heat treatment Thus, the antibacterial polymer material can be produced by a method of reducing the metal salt to produce ultrafine metal particles in the polymer.

In the case of fiber, ultrafine metal particles can be added before spinning, and in the case of resin, before injection molding, it is possible to add antibacterial property by post-treatment. As the post-treatment, a method of coating the polymer surface with a film in which ultrafine metal particles are dispersed, coating a coating solution containing a metal salt on the polymer surface, and then performing heat treatment,
Method of reducing metal salt in the coating film to form ultrafine metal particles in the film, island-shaped ultrafine metal particles are formed on the polymer surface by sputtering or vapor deposition, and then thermally diffused.
Examples thereof include a method of producing ultrafine metal particles in a high concentration near the surface of a polymer.

If necessary, it is possible to use an antibacterial organic substance together with ultrafine metal particles. As it can be used for various fibers, it can be used for all clothing,
As an antibacterial fiber for carpets, curtains, towels, rags, masks, carpets, etc., all areas where ordinary plastics are used in resin, especially applications where water is present, for example, bath products, kitchen appliances, refrigerators, air conditioning Household appliances such as appliances and humidifiers, household goods, interior materials such as vinyl cloth and floor materials, civil engineering materials such as drainage pipes and tarpaulins,
It can also be used for cutting boards, water purifiers, food-related products such as wrapping films and bags for wrapping food, electronics-related products such as electric wire clothing, printed circuit boards, contact lenses, glasses, diapers, and rubber. In addition, it can be used as a soil improving agent such as mortar and glass for construction, and as an antibacterial and antifungal agent for gardening, agriculture, lawns such as golf courses, baseball fields, and parks.

[0019]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. The following test methods were used for evaluation of antibacterial effect and washing conditions in the examples. <Evaluation of antibacterial effect> The shake flask method was used. The test bacterium is Staphylococcus aureus ATCC
6538P (IFO 12732)), the weight of the test piece is 0.75 g, and the shaking condition is wrist action shaking at 330 rpm for 1 hour, and after measuring the viable cell count in the flask,
The sterilization rate was calculated by the following formula. Sterilization rate (%) = (B−A) × 100 / B where A is the number of bacteria per 1 ml in the flask after shaking, and B is the number of bacteria per 1 ml in the flask before shaking. Show.

This time, it was judged that the antibacterial performance was obtained with a sterilization rate of 26% or more. <Washing test method> The washing test is carried out according to JIS L0217-103, and 2 g of a detergent for clothes is added and dissolved in 1 liter of water having a liquid temperature of 40 ° C to obtain a washing liquid. A sample and a load cloth are put in this washing liquid so that the bath ratio becomes 1:30, and the operation is started. After the treatment for 5 minutes, the operation is stopped, the sample and the load cloth are dehydrated by a dehydrator, and then the washing liquid is changed to fresh water at room temperature, rinsed with the same bath ratio for 2 minutes and air-dried. A sample after the above operation was repeated 10 times was used as a laundry. <Measurement of silver content> After wet decomposition of the sample with nitric acid,
It was dissolved in 10 ml of 1N nitric acid and measured using ICP. (Absolute calibration curve method)

[0021]

Example 1 A coating liquid containing the following components was prepared. Silver trifluoroacetate 0.01 g 2,2'-methylenebis (4-ethyl-6-t-butylphenol) 0.2 g Polyurethane 100 g Isopropyl alcohol 700 g Toluene 500 g This coating solution was filtered through a filter having an average pore size of 0.2 μm. After that, nylon 6 (product number 1) manufactured by Asahi Kasei Co., Ltd. was used so that the film thickness after drying was 6 μm with a blade coater.
162) Apply evenly on the cloth, temperature 30 ℃, humidity 45%
It was dried under the condition of RH. The sample was heated at 150 ° C. for 20 minutes. A section for a transmission electron microscope was prepared from this sample using a microtome and observed using an electron microscope. The electron microscope is JEM-4000 manufactured by JEOL Ltd.
It was examined using FX. The diameter of 100 silver particles within a certain range of the photograph was measured, and the arithmetic average particle diameter was 26n.
It was m. The silver content was 49.9 ppm.

Evaluation by the shake flask method is 91
%, And that for laundry was 84%. The blank at this time is 0
%, And the nylon standard cloth was 0%.

[0023]

Comparative Example 1 A suspension having the following composition was prepared. High-purity chemical reduced silver powder (particle size: about 2 μm) 0.05 g Urethane 100 g Isopropyl alcohol 700 g Toluene 500 g After homogenizing this suspension using a ball mill, it was filtered using a filter with an average pore size of 5 μm, and then a blade coater. Was uniformly applied onto a nylon 6 (product number 1162) cloth manufactured by Asahi Kasei Co., Ltd. so as to have a film thickness of 6 μm after drying, and dried at a temperature of 30 ° C. and a humidity of 45% RH. The silver content was 498 ppm.

The evaluation of the shake flask method is 10 for the original product.
% And 8% for laundry, and it was judged that there was no antibacterial property. At this time, the blank was 0% and the nylon standard cloth was 0%.

[0025]

Example 2 A masterbatch was prepared as follows. A coating liquid having the composition shown below was prepared. Polystyrene 10 g Silver heptafluorobutyrate 0.01 g 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate
0.02 g Methyl ethyl ketone 60 g Toluene 30 g The solvent was removed from this coating solution using an evaporator, and then heat treatment was carried out at 150 ° C. for 30 minutes in an oven, followed by pulverization into chips to prepare a masterbatch. Using this masterbatch, the silver content is 0.05wt
% And mixed with polystyrene to perform injection molding to prepare an antibacterial evaluation sample.

The particle size was measured using an electron micrograph, and the average particle size was 9 nm. Silver content is 295p
It was pm. When Staphylococcus aureus was placed on the sample and cultured at 30 ° C. and a constant temperature and humidity of 50%, the growth of the bacteria was almost prevented even after 4 weeks.

[0027]

Example 3 A masterbatch was prepared as follows. A liquid having the composition shown below was prepared. Silver trifluoroacetate 0.1 g Methanol 15 g After immersing the nylon 6 pellets in this solution overnight, the pellets were taken out from the solution, the solvent was removed, and then heat treatment was performed at 150 ° C. for 30 minutes using an oven. Using this masterbatch, nylon 66 chips were mixed so that the amount of silver was about 50 ppm to prepare a 10 denier yarn. Then, a cloth was produced using this thread. When the particle size was measured using an electron micrograph, the average particle size was 19
was nm. The silver content was 48.9 ppm.

When evaluated by the shake flask method, the sterilization rate was 97%.

[0029]

Example 4 A sample was prepared in the same manner as in Example 3. However, it was prepared so that the amount of silver was 5 ppm. The silver content of the produced sample was 4.9 ppm. The average particle size was 4 nm, and when evaluated by the shake flask method, the sterilization rate after washing was 78%.

[0030]

Comparative Example 2 A sample was prepared in the same manner as in Example 4. However, it was prepared so that the amount of silver was 0.05 ppm. The silver content of the produced sample was 0.05 ppm. The average particle size was 3 nm, and the sterilization rate after washing was 25% as evaluated by the shake flask method.

[0031]

Example 5 Copper was sputter-deposited at room temperature on a surface of styrene pellets manufactured by Asahi Kasei to a film thickness of 5 nm using a sputtering apparatus. This sample was used as a masterbatch. The masterbatch was charged so as to be 1/10 of the whole, kneaded using a 30 mm uniaxial extruder, and pellets were prepared again. With this pellet,
Injection molding was performed to prepare an evaluation sample. As a result of electron microscopic observation, the average particle size of the ultrafine particles was 25 nm. The copper content was 100 ppm. When evaluated by the shake flask method, the sterilization rate after washing was 85%.

[0032]

INDUSTRIAL APPLICABILITY The present invention is an antibacterial material capable of using various polymer base materials, having high antibacterial performance and good durability. Further, since the particle size is small, there is no problem even when kneading with fibers or resins, and it is useful that the manufacturing process up to now is not significantly changed and the performance is extremely reduced.

Claims (2)

[Claims] 1. An antibacterial material, wherein ultrafine metal particles having an average particle size of less than 200 nm are dispersed in a base material in an amount of 0.1 ppm or more. 2. The antibacterial material according to claim 1, wherein the ultrafine metal particles are ultrafine particles containing at least one selected from silver, copper, zinc, iron, mercury, lead, tin, bismuth, cadmium and chromium.