JPH0421517A - Antibacterial zeolite - Google Patents

Abstract

PURPOSE:To obtain an antibacterial zeolite having excellent antibacterial activity and causing little discoloration and color change with time when compounded to a resin by introducing silver ion and a bivalent metal ion to a zeolite by ion-exchange treatment. CONSTITUTION:The antibacterial zeolite of formula is produced by introducing silver ion and a bivalent metal ion to a zeolite by ion-exchange treatment. In the formula, 1.8<=m<=10, 0<=n<=5, M' is bivalent metal of group IIA, group IB or group IIB of the periodic table and M'' is an alkali metal. x, y and z satisfy the relationships 0.8<=x+y+z<=1.2; 0<x<=0.2, y>=0.2; z<=0.7 and y/z<=20 (molar ratio) and the weight ratio of Cl/Ag is <=0.01. The obtained antibacterial zeolite is suitable for imparting antibacterial activity to synthetic resin, rubber, paper, textile, feed, food, etc.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to antibacterial zeolite, and more specifically, it has excellent antibacterial properties, has little coloring itself, and when blended into synthetic resin. This invention relates to antibacterial zeolite that does not deteriorate or color synthetic resins.

[Conventional technology]

Conventionally, antibacterial zeolite, which is made by adsorbing and supporting antibacterial metal ions on zeolite as a carrier, is well known, and in particular, silver ion-supported zeolite has excellent antibacterial properties, so it has recently become popular. Development is booming.

For example, JP-A-60-181002 discloses that antibacterial properties obtained by replacing some or many of the ion-exchangeable ions in natural or synthetic zeolite with metal ions such as silver, copper, and zinc Zeolite has been disclosed, and is also disclosed in Japanese Patent Application Laid-Open No. 63-26580 and Japanese Patent Application Laid-Open No. 1-2
No. 57124 proposes an antibacterial zeolite obtained by replacing ion-exchangeable ions in zeolite with ammonium and antibacterial metal ions, or alkaline earth metals and the like with antibacterial metal ions.

[Problem to be solved by the invention]

Since this type of antibacterial zeolite has a long-lasting and excellent antibacterial effect, its use as a typical inorganic antibacterial agent is being rapidly developed.

However, in particular, antibacterial zeolite that supports silver ions often tends to be colored pale yellow or grayish brown by itself, and when it is added to synthetic resins or rubber, it is also affected by the processing temperature. It has the drawback of imparting undesirable coloring and significantly impairing its commercial value. Also,
Even if coloring after processing is fortunately avoided through careful selection of compounds, the coloring will gradually change over time. This coloring phenomenon tends to be significantly accelerated by exposure to light.

This browning phenomenon of silver zeolite is thought to be due to the chemical action of silver ions, as well as to the fact that it accelerates the deterioration of the resin during blending into resin and molding under heating.

In order to suppress such a coloring phenomenon, it is known to support, for example, ammonium ions as described above or ammine complex ions.

Another method proposed is to use a UV inhibitor in combination.

However, despite many development efforts to date, no technical development has been made to the extent that antibacterial zeolites carrying silver ions can be commercially provided as stable products with suppressed coloration.

An object of the present invention is to provide an antibacterial zeolite that solves these problems.

[Means for Solving the Problems] In view of the fact that the ridges are present, the present inventors have conducted numerous studies to solve this problem, and have found that the discoloration of the antibacterial zeolite itself and its change over time are caused by antibacterial metal ions. Development of color-fast antibacterial zeolite based on the knowledge that the interaction between supported silver ions and other metal ions and the Naz O component and halogen content remaining in zeolite are dominant. The present invention was successfully completed.

That is, the antibacterial zeolite to be provided by the present invention relates to an antibacterial zeolite having resistance to discoloration, and its characteristics are that the antibacterial zeolite supports at least silver ions through ion exchange treatment, and the zeolite has the following characteristics: Its structural feature is that it has conditions.

(1) The general formula is ((Agz O)x (M' O)y
(M”10)z ) ・Al1t Os ・m5i
Oz ・nHt In the OC formula, m and n are each 1.8≦
m≦10, Own≦5, M' is synchronous table group IIA, IB
The synthetic zeolite is a divalent metal belonging to Group 1 or Group IIB, M' is an alkali metal.

(2) 0.8≦x+y+z≦1 for each of x, y, and z,
It has a molar ratio relationship of 2.0<x≦0.2, y≧0.2 and 2≦0.7.

(31y/x≦20, and weight ratio Cj2/Ag≦
have a relationship of 0.01.

The present invention will be explained in detail below.

The synthetic zeolite used as a raw material when producing the antibacterial zeolite according to the present invention is a crystalline aluminosilicate, often sodium aluminosilicate [
Na, ○・A1.03 ・mS io, -nH, O)
Various synthetic zeolites having m values in the range of 1.8 to 10 can be used. Practically speaking, examples include A-type zeolite, X-type zeolite, Y-type zeolite, P-type zeolite, and mordenite, but from an economic standpoint, A-type zeolite is particularly preferred.

The average particle diameter (Di.) of these synthetic zeolites is 0.1
~Ion, preferably in the range of 0.5 to 5-, and with a sharp particle size such that particles having a particle size of 1/2 to 3/2 of D50 account for at least 50%, preferably 60% of the total. Those having a distribution are particularly good.

Further, the particle shape is preferably substantially spherical with the corners and edges of the crystalline zeolite removed.

These particle characteristics are virtually unchanged in the relationship between the raw material zeolite and the antibacterial zeolite obtained by ion-exchanging it, and it can be said that the particle characteristics of the antibacterial zeolite are all those of the raw material zeolite. can.

In the antibacterial zeolite according to the present invention, in terms of ion exchange rate with respect to the raw material zeolite, silver ions need to have an ion exchange rate of 1 to 10% with respect to the original sodium ions. If it is less than 1%, the antibacterial activity will be insufficient, while if it exceeds 10%, the antibacterial activity will be saturated and the tendency for discoloration will be strong.

The metals other than silver ions supported by ion exchange are one or more divalent metals belonging to Group IIA, Group IB, or Group IIB of the periodic table, and the ion exchange rate of these metals is at least 20% for sodium
is necessary.

In terms of antibacterial activity, when antibacterial metal ions such as gold, copper, zinc, or mercury are used together with silver ions, the antibacterial spectrum is expanded, and the effect against a wider variety of bacteria and molds is exhibited.

On the other hand, from the viewpoint of resistance to discoloration, it is preferable to support metal ions such as magnesium, calcium, copper, or zinc in the divalent metal. Furthermore, from the viewpoint of discoloration resistance of antibacterial zeolite, it is important that the content of sodium and chlorine ions is particularly low, and the sodium content is
10% by weight or less, especially 8% by weight or less as ag O,
Further, it is desirable that the chlorine ion has a cp of 200 ppg+ or less, particularly 150 ppg or less, which is as unsuitable as possible.

In the present invention, the mutual relationship between sodium, chlorine, and silver ions is also important, and the molar ratio M'O/Ago (M' has the same meaning as above) is 20 or less, and the weight ratio C!!/Ag is 0.01n.
The following is necessary for discoloration resistance.

If the NazO content in the antibacterial zeolite exceeds 10% by weight, the synthetic resin composition containing the antibacterial zeolite will accelerate deterioration during kneading or hot molding, and will increase its tendency to color.

In addition, since chlorine is a photosensitive silver chloride and causes discoloration of zeolite, it must not exceed the above value, and M'O
When /Ag, O is 15 or less, it effectively affects discoloration resistance.

As can be seen from the above, the antibacterial zeolite according to the present invention is obtained by ion-exchanging the synthetic zeolite as a raw material so that it always carries predetermined amounts of divalent metal ions in addition to silver ions.

Therefore, when this is expressed by the above general formula (1), (
It is particularly important to satisfy the characteristics 2) and (3) from the viewpoint of both antibacterial properties and discoloration resistance.

Incidentally, ion exchange treatment is well known, and the antibacterial zeolite according to the present invention can be produced by conventional means, and the obtained antibacterial zeolite has an equilibrium pH of 5% suspension of 10.
It is desirable to adjust as follows in order to suppress the promotion of discoloration.

The antibacterial zeolite according to the present invention can be applied to various purposes as a typical inorganic antibacterial agent. For example, it can be added to synthetic resins, rubber, paper, fibers, feed, foods, etc. to impart antibacterial activity to them. I can do it.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

In addition, each measurement value in an Example was calculated|required by the following method, respectively.

(1) Particle size distribution and average particle size Measured using a Coulter Counter (manufactured by Coulter Electronics) with an aperture tube of 30 trm.

(2) Composition analysis Metal components were determined by atomic absorption spectrophotometry and ICP method, and CZ was determined by turbidimetry.

(3) Loss on ignition (moisture content) 1 g of a sample was weighed into a porcelain crucible, heated at 800°C for 1 hour, and the weight loss was determined from the weight loss.

(4) Equilibrium pH 5g of sample was added to 100+/! of smoked water! After stirring at 25°C for 30 minutes, a pH meter (M5 manufactured by Hitachi Horiba) was used.
It was measured with

(5) Whiteness The brightness was determined using a blue filter with a whiteness needle manufactured by Kerato Co., Ltd., targeting maggotium oxide.

Example 1 Type A zeolite, Type X zeolite, and Type P zeolite shown in Table 1 were used as raw material synthetic zeolites.

Table 1 As salts for ion-exchanging these zeolites, nitrates of Ag, Ca, Mg, Zn and Cu were used.

Each sample was prepared according to the following procedure. That is, after washing 1 kg of zeolite powder in Table 1 with 1 distilled water, 5 j of distilled water
2 was dispersed and suspended. While stirring the suspension, an appropriate amount of 5 wt % nitric acid was added to adjust the pH to 6-7. Next, an aqueous solution 5i in which a predetermined amount of salts had been dissolved was added, and the mixture was stirred at room temperature for 3 hours to perform ion exchange.

The solid phase was separated and washed by a conventional method, then dried and pulverized.

Table 2 shows the composition and properties of each sample obtained and the conditions for their preparation. In addition, each sample showed almost the same shape, size, and particle size distribution as the raw material zeolite used.

Example 2. (Antibacterial test) The antibacterial properties of each sample were evaluated by the following method.

0.5 g of the sample was added to 50 Il of previously prepared bacteria-contaminated water (Note 1) or mold diluted water (Note 2), and the mixture was slowly stirred for 10 minutes using a mug tink stirrer. Next, this liquid was measured using simple microorganism measuring instruments Easy Cal) TTC (for testing aerobic bacteria, fungi, and yeasts: a product of San-Ai Oil Co., Ltd.) and Easy Cal) M (for testing fungi and yeasts: a product of San-Ai Oil Co., Ltd.). A culture test (Note 3) was conducted.

The results are shown in Table 3.

(Note 1): River water is diluted with sterile water, the number of bacteria is 105, and for a total bacteria test (Note 2): 1 g of black mold-infested wall soil is mixed with 100 sf of sterile water! For fungal testing (Note 3): Culture was carried out for 2 days (total bacteria) or 4 days (fungi) in an incubator at 27-30°C.

Table 3 (Note 4): 11! The number of bacteria was evaluated based on the relationship between the degree of colony occurrence and the number of bacteria roughly determined in advance. 0 means no occurrence of locony.

(Note 5): The degree of fungal contamination was evaluated in the following four stages.

- No double contamination Twelve mild pollution ++: Moderate pollution 10++2 intensity pollution (Note 6): When antibacterial zeolite is not added.

Example 3 (4!L fat discoloration test) For 100 parts by weight of polypropylene (J-209),
One part by weight of each sample was mixed and injection molded at a temperature of 220'C to obtain test pieces each having a size of 180-mist X5+u+X1 mm. The whiteness (reflectance) of these test pieces was measured immediately after molding and after 30 days of sunlight irradiation using a Photovolt reflectometer manufactured by Toyo Seiki Co., Ltd. (equipped with B filter).

The measurement results are shown in Table 4.

Table 4 (Note 1) : Antibacterial zeolite If no additive was added.

〔Effect of the invention〕

The antibacterial zeolite according to the present invention has antibacterial activity equivalent to that of conventional antibacterial zeolite, and when it is blended into, for example, synthetic resin, the coloring of the resin is significantly suppressed compared to conventional products, and the coloring of the resin is suppressed over time. Because it exhibits very little color change, it is extremely useful as a material for imparting antibacterial properties to resins.

Applicant: Nihon Kagaku Kogyo Co., Ltd. (one other person) Agent: Masaya Takahata, patent attorney

Claims (1)

[Scope of Claims] 1. An antibacterial zeolite carrying at least silver ions through ion exchange treatment, characterized in that the zeolite has the following conditions. (1) The general formula is [(Ag_2O)x(M'O)y(M''
_2O)z]・Al_2O_3・mSiO_2・nH_
2O [in the formula, m and n are each 1.8≦m≦10.0≦n
≦5, M' is a divalent metal belonging to Group IIA, Group IB, or Group IIB of the periodic table, and M'' is an alkali metal. (2) x, y, and z are 0.8≦x+y+z≦1, respectively.
2. Having a molar ratio relationship of 0<x≦0.2, y≧0.2 and z≦0.7. (3) y/x≦20 and weight ratio Cl/Ag≦0.01
have a relationship with 2. Whiteness of 95.5%, with an average particle diameter (D_5_0) in the range of 0.1 to 10 μm, and a particle size distribution in which 1/2 to 3/2 of D_5_0 accounts for at least 50% of the whole. Claim 1 which is the above A-type zeolite.
Antibacterial zeolite as described.