JP2000302616A - Antibacterial resin composition, antibacterial composition and molded product therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition generating no deterioration and discoloration at processing and with the passing of time by mixing respectively specific antibacterial agent and salicylic acid derivative into a resin. SOLUTION: This composition is obtained by mixing (A) an antibacterial agent comprising a mixture of (i) zinc oxide covered with silver or a silver alloy and (ii) zinc oxide not covered and (B) a salicylic acid derivative having 1,2,4-triazole ring (e.g. 4-salicylideneimino-3,5-diphenyl-1,2,4-triazole) into (C) a resin. Preferably, the component C is a polyolefin-based resin polymerized with a polymerization catalyst containing a halogen element and 0.2-30 wt.% of the component B based on the component A is contained in the component A, e.g. in the component A, a content of the component (i) may be about 1-20 wt.% and an adding amount of the component A may be about 0. 05-10 wt.% based on the total amount of the objective composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an antibacterial resin composition, an antibacterial composition and a molded article having excellent color stability.

[0002]

2. Description of the Related Art In recent years, products having antibacterial properties have been widely used due to requirements for comfort and hygiene. As a means for imparting antibacterial properties to these products, a method of adding an antibacterial agent to a resin and molding (kneading type) or a method of coating a molded article with a resin coating agent containing an antibacterial agent (coating type) is generally used. Has been used in many ways.

Conventionally used inorganic antibacterial agents include antibacterial properties (bactericidal and bacteriostatic) of metals or metal ions.
There are many that used. A small amount of metal ions such as silver, copper, and zinc that have high antibacterial and bactericidal effects, especially adsorbed and supported on zeolite, silica, etc. by ion exchange, etc., or solidified in phosphate, water glass, etc. What was made to be used is used.

[0004] The bactericidal action mechanism of the silver component is that the silver component eluted in the presence of water reacts with the main enzyme distributed on the cell membrane on the surface of bacterial cells (cells) to inhibit the enzymatic action, or It has been suggested that bacteria are killed by generating active oxygen by irradiation with visible light in the presence of.

The antibacterial effect of such a mechanism often has an adverse effect on the coexisting resin component. When an antibacterial agent containing a silver component and a resin are mixed and molded, heat during processing causes a decrease in mechanical properties and the like, and the color of the originally transparent to translucent resin changes from yellow to brown or is used. In some cases, similar physical property deterioration and discoloration may occur, but if the amount of silver component eluted is reduced in order to prevent these drawbacks, there is a disadvantage that the antibacterial effect is reduced.

[0006] It is well known that the oxidative degradation of resin components is accelerated in the presence of certain heavy metals.
This is due to catalytic decomposition of peroxide by a trace amount of metal compound, activation of oxygen, reaction between metal and substrate, radical generation by decomposition of metal compound, photosensitization, and the like. Further, active oxygen generated from the antibacterial agent also promotes oxidative deterioration of the resin.

In particular, a polypropylene resin, a linear low-density polyethylene resin, a high-density polyethylene resin, etc. polymerized using a polymerization catalyst containing a halogen element, for example, a Ziegler-Natta type catalyst, may coexist with a metal component such as silver. In particular, discoloration from yellow to brown is remarkable. This is presumed that the halogen atoms in the remaining catalyst react with the metal ions. Such discoloration and deterioration of physical properties significantly lower the utility value as a material.

In order to improve these drawbacks, a method of inactivating catalyst residues with a heavy metal deactivator to prevent discoloration by a zeolite compound holding a metal component (Japanese Unexamined Patent Publication No. 4-117440) has a hiding property. A method of adding a white pigment to prevent discoloration (JP-A-10-140012),
Method using silver fine particles coated with wax
No. 5,195,957), or a method of forming a coating layer containing metal on hollow particles (Japanese Patent Laid-Open No. 7-196424).

[0009]

However, these conventional methods are insufficient for preventing discoloration of the inorganic antibacterial resin composition, and the production method is complicated. Therefore,
There has been a problem that it is still difficult to obtain an antibacterial resin composition and a molded product that are not deteriorated or discolored during processing and over time.

[0010]

That is, a first aspect of the present invention provides an antibacterial agent comprising a mixture of zinc oxide coated with silver or a silver alloy and uncoated zinc oxide,
-A salicylic acid derivative having a triazole ring and an antibacterial resin composition obtained by mixing the resin with a resin.

A second invention is the antibacterial resin composition according to the first invention, wherein the resin is a polyolefin resin polymerized by a polymerization catalyst containing a halogen element.

A third invention provides a method for forming a 1,2,4-triazole ring on an antibacterial agent comprising a mixture of zinc oxide coated with silver or a silver alloy and uncoated zinc oxide according to the first invention. It is an antibacterial composition to which 0.2 to 30% by weight of a salicylic acid derivative is added.

A fourth invention is a molded article obtained from the antibacterial resin composition according to any one of the first and second inventions.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. Zinc oxide used in the antibacterial agent of the present invention is also called zinc white or zinc white. The method for producing zinc oxide includes an American method, a French method, a wet method, a special method, and the like, and is not particularly limited in the present invention. Ordinary zinc oxide is classified as special number 1, 2, or 3 according to its quality.
Among them, special No. 1 having high purity and high whiteness is preferable. Further, composite particles in which inert particles are coated with zinc oxide may be used.

The particle size of zinc oxide is not particularly limited, but is preferably 0.1 to 5 μm. If the particle size is very small,
When added to a resin, it tends to aggregate and uniform dispersion cannot be expected. On the other hand, if the particle size is excessively large, the coloring becomes conspicuous when coated with silver particles and is recognized as a black spot on the surface of the molded product, which is not preferable.

In the present invention, silver alone or a silver alloy (hereinafter, referred to as silver alloy)
These are called silver or the like. ) Is coated on the surface of zinc oxide and used as an antibacterial component. For coating, any of silver alone, silver alloy alone, and a mixture of silver and silver alloy may be used. As a method of coating silver or the like on the zinc oxide surface, electroless plating in an aqueous solution is not appropriate because zinc oxide has a slight solubility in water and coagulation occurs in a drying step after plating. However, a dry method such as vapor deposition is preferable. Among them, the sputtering method is preferable because the silver component is partially atomized and adheres to the surface of the zinc oxide particles, so that a large amount of silver elutes during actual use, and the antibacterial property is easily expressed, and is preferred.

As the silver alloy, Cu, Zn, Sn, Ni,
A silver alloy containing one or more of Cr, Co, Sb, Ti, Al and the like can be used. Particularly preferably, Ag / C
u / Zn alloy or Ag / Cu / Zn / Ni alloy. Among them, Cu having an antifungal effect, Sn having antibacterial properties against specific bacteria such as Thiobacillus,
When zinc oxide is coated with an alloy containing Ni or the like, in addition to antibacterial properties derived from silver, it is expected that these effects can be exerted. However, in order to ensure the antibacterial properties of silver, the total content of alloying elements is preferably 10% by weight or less.

The coating amount of silver or the like on zinc oxide is 0.5
-20% by weight is preferred. If the amount is less than 0.5% by weight, the antibacterial property of the silver component is hardly exhibited, and if it exceeds 20% by weight, blackening of the powder is remarkable. This is coloring by silver attached to the surface. From the viewpoint of versatility of the antibacterial agent, it is preferably transparent to white, so that 2 to 10% by weight, which can balance the antibacterial property and the color tone of the powder, is particularly preferable.

When an antibacterial agent comprising zinc oxide coated with silver or the like and zinc oxide not coated is added to the resin, whiteness is improved as compared with a case where only zinc oxide coated with silver or the like is added, Further, the antibacterial property is also improved. This is presumably because zinc oxide itself, which is not coated with silver or the like in the antibacterial agent, has a low hiding power but is white and has weak antibacterial activity. Improving the whiteness of a molded product while exhibiting antibacterial properties increases the degree of freedom of coloring, and is important as a property of an antibacterial agent.

Therefore, the antibacterial agent of the present invention is a mixture of zinc oxide coated with silver or the like and zinc oxide not coated. The proportion of zinc oxide coated with silver or the like in the antibacterial agent is preferably from 1 to 20% by weight, and particularly preferably from 3 to 10% by weight from the balance between whiteness and antibacterial properties.

When the antibacterial agent of the present invention is added to a resin, the amount of the antibacterial agent to be added is from 0.05 to the total weight of the resin composition.
10% by weight, especially 0.2 to 3% by weight, is preferred.

When the amount of the antibacterial agent is less than 0.05% by weight, the antibacterial effect is hardly exhibited, and when it exceeds 10% by weight, the effect corresponding to the increase in the added amount is hardly obtained. Various combinations such as a mixing ratio of zinc oxide coated with silver or the like and zinc oxide not coated or the amount of addition to the resin are possible, but in order to express good antibacterial properties, it is necessary to use a resin composition. 0.001 to 0.005% by weight of silver component to total weight
It is desirable that This is because most of the presence or absence of antibacterial properties is determined by the amount of silver component added. The amount of zinc oxide to be added is taken into consideration in view of whiteness and cost requirements.

On the other hand, chelating agents having a chelating ability such as oxalic acid, citric acid, salicylic acid, 8-quinolinol, and chelating dyes are known to prevent oxidative deterioration of resin components due to heavy metals contained in the resin. I have.
However, such chelating agents may volatilize into the atmosphere or elute into water during use, or the heavy metal chelates themselves may impart undesirable coloration to the resin.

Chelating agents having properties preferable as resin additives include oxalic acid derivatives, hydrazine derivatives, salicylic acid derivatives, etc. The oxalic acid derivatives and hydrazine derivatives prevent discoloration of the resin and deterioration of physical properties due to metallic silver. No effect was seen. However, among the salicylic acid derivatives, only a compound having a 1,2,4-triazole ring showed an excellent effect in preventing discoloration.

The salicylic acid derivative having a 1,2,4-triazole ring used in the present invention is obtained by bonding a 1,2,4-triazole ring to a carboxylic acid of salicylic acid by various methods. Such compounds include 4-salicylideneimino-3,5-diphenyl-
1,2,4-triazole, 3- (N-salicyloyl)
Amino-1,2,4-triazole, 3- {N-β-
(3,5-di-t-butyl-4-hydroxyphenyl)
And propionylamino-1,2,4-triazole.

In order to maintain the function of preventing discoloration for a long period of time, it is necessary to suppress volatilization and elution of a salicylic acid derivative having a 1,2,4-triazole ring from a resin composition or a molded article. The melting point of the salicylic acid derivative having a 1,4-triazole ring is preferably higher.

Further, by heating operation during processing, etc.,
Since the salicylic acid derivative having a 2,4-triazole ring and the silver component in the antibacterial agent may be chelated to lower the antibacterial property, the melting point of the salicylic acid derivative having a 1,2,4-triazole ring is higher than the processing temperature. Is also preferable. Since most general-purpose resins are processed at a temperature lower than 300 ° C., 3- (N-salicyloyl) amino-1,2,4-triazole having a melting point of 300 ° C. or higher does not melt at the above processing temperature, and silver Because there is little chance of contact with
Particularly preferred. This substance is also preferable in that it is easily available. The reason why the salicylic acid derivative having a 1,2,4-triazole ring has an excellent discoloration preventing ability is not clear, but it is considered that the positional relationship between the hydroxyl group of salicylic acid and the triazole ring matches the size of the silver atom. .

When the salicylic acid derivative having a 1,2,4-triazole ring of the present invention is added to a resin, when the amount of the antibacterial agent is 0.05 to 10% by weight, 1,2,4
-Salicylic acid derivative having a triazole ring is 0.0%
It is preferably from 0.5 to 0.5% by weight.

Particularly, when the content is 0.01 to 0.3% by weight, both discoloration prevention and antibacterial properties are compatible, and a favorable result is obtained. 1,2,4
The salicylic acid derivative having a triazole ring is 0.00
If it is less than 5% by weight, the effect of preventing discoloration is not sufficient,
If the amount is more than 10% by weight, the effect of the antibacterial agent tends to be impaired. 1,
A salicylic acid derivative having a 2,4-triazole ring exhibits an effect of preventing discoloration when added in a very small amount, and thus hardly impairs the antibacterial effect. Further, this additive can be easily mixed into the resin, and has high industrial value.

In the antibacterial composition of the present invention, it is desirable to add a salicylic acid derivative having a 1,2,4-triazole ring in an amount of 0.2 to 30% by weight, and 1 to 20% by weight, based on the antibacterial agent. Especially desirable. The mixture of the antibacterial agent and the salicylic acid derivative having a 1,2,4-triazole ring mixed in the above ratio can be used as an antibacterial composition with little discoloration during processing and with time.

In particular, in the case of an olefin resin polymerized using a polymerization catalyst containing a halogen element, for example, a Ziegler-Natta catalyst, silver may react due to the effect of the catalyst residue and discoloration may occur significantly. The optimum amount of the salicylic acid derivative having a 1,2,4-triazole ring in the antibacterial composition tends to vary widely depending on the production method, grade and the like. However, in many olefin-based resins, the amount of addition for achieving both the discoloration prevention effect and the antibacterial effect is 0.02 to 0.15 of the salicylic acid derivative having a 1,2,4-triazole ring based on the total weight of the resin composition.
% By weight.

The resins used in the present invention include epoxy resins, urea resins, melamine resins, alkyd resins, etc. as thermosetting resins, and polyethylene resins, polypropylene resins, polybutene-1 resins, 1,2 as thermoplastic resins.
Polybutadiene resin, polyvinyl chloride resin, polyvinyl acetate resin, polystyrene resin, polyacrylonitrile resin, acryl-butadiene-styrene (ABS) resin,
Polyester resin, polycarbonate resin, nylon resin, polyacetal resin, etc., and synthetic rubbers such as styrene butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), butadiene rubber (BR), and isobutylene-isoprene rubber (II)
R), ethylene-propylene rubber (EPR), and the like, and examples of the natural resin include natural rubber, gutta percha, and asphalt. Further, copolymers, mixtures, polymer alloys, and the like of these resins are included.

When the antimicrobial composition comprising the antimicrobial agent and the salicylic acid derivative having a 1,2,4-triazole ring according to the present invention is added to the resin, the respective components in the antimicrobial composition are added according to the desired amount. After separately preparing, they may be added simultaneously or stepwise. For example, there is a method in which an antibacterial agent is charged into a resin, melt-kneaded, and after sufficient dispersion is confirmed, a salicylic acid derivative having a 1,2,4-triazole ring is added. Alternatively, the respective components in the antibacterial composition may be mixed in advance using a suitable mixer and then charged into the resin.

When a molded article is obtained using a thermoplastic resin,
A thermoplastic resin composition containing a high concentration of an antimicrobial agent and a salicylic acid derivative having a 1,2,4-triazole ring, a so-called masterbatch (hereinafter, referred to as MB) is prepared.
Method for obtaining molded article by diluting MB with thermoplastic resin, MB containing high concentration of antibacterial agent and MB containing salicylic acid derivative having 1,2,4-triazole ring in high concentration
, And mixing and diluting two types of MB with a thermoplastic resin to obtain a molded article.
-There is a method of obtaining a molded article by processing the antibacterial resin composition obtained by melt-kneading a salicylic acid derivative having a triazole ring and a thermoplastic resin, without diluting the composition.
In the case of the method described above, the antibacterial resin composition before molding is called a compound.

The thermoplastic resin used for the production of MB and the thermoplastic resin for dilution may be either the same kind of resin or a different kind of resin. That is, from the viewpoint of versatility of MB, it is preferable to produce one kind of MB and dilute MB with various thermoplastic resins. On the other hand, from the viewpoint of compatibility between MB and the thermoplastic resin for dilution, it is preferable to use the same type of resin. The same applies to the case of.

Although the reason for using MB or compound has not yet been elucidated in detail, the degree of manifestation of antibacterial properties differs slightly depending on the type of thermoplastic resin which is the main component of the molded article. For example, ABS
In the case of (1), the antibacterial property is less likely to be exhibited than in the case of polypropylene. Therefore, it is preferable to mix the antibacterial resin composition slightly more than in the case of polypropylene.

The antimicrobial resin composition of the present invention may contain other known additives such as a coloring dye, depending on the intended use.
Pigments, antistatic agents, antioxidants, ultraviolet absorbers, or the like, or dispersants such as metal soaps may be added.

The antibacterial resin composition of the present invention is, for example,
It is obtained by melt-kneading an antimicrobial agent, a salicylic acid derivative having a 1,2,4-triazole ring, and a resin component using an extruder or the like.

The antibacterial resin composition thus obtained can be formed into a molded article or a coating having antibacterial properties by a conventional molding method. For example, injection molding, compression molding, and the like for a thermoplastic resin, and molding by casting for a thermosetting resin.

Alternatively, in the case of a coating agent, an antibacterial agent and a salicylic acid derivative having a 1,2,4-triazole ring or an antibacterial composition are added and dissolved and mixed in the production of paints and inks. Paints, antibacterial inks, and antibacterial adhesives, and can be formed into antibacterial films on desired articles through coating and drying processes, but are limited by the molding method or form. is not.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited in any way by these examples.

[0042]

The present invention will be described below in more detail with reference to examples. Antibacterial agent: Zinc oxide (average particle size 0.8 μm, manufactured by Sakai Chemical Co., Ltd.) with 6.7% by weight of silver adhered by sputtering, 5% by weight of silver-coated zinc oxide and 5% by weight of uncoated zinc oxide A mixture of 95% by weight of zinc was prepared by stirring and mixing for 5 minutes using a Henschel mixer. Salicylic acid derivative: 3- (N-salicyloyl) amino-
1,2,4-triazole (trade name ADK STAB CDA
-1, Asahi Denka Co., Ltd.) or decanedicarboxylic acid disalicyloyl hydrazide (trade name: ADK STAB CDA-6, manufactured by Asahi Denka Co., Ltd.).

Resin: ABS resin (trade name TECHNO)
ABS 350 (manufactured by Techno Polymer Co., Ltd.) or a polypropylene resin (Grand Polypro J-707, manufactured by Grand Polymer Co., Ltd.) polymerized with a Ziegler-Natta catalyst was used. After mixing the above antibacterial agent, salicylic acid derivative, and resin according to the formulations in Tables 1 to 3, 2
5cm x 9c by an injection molding machine set at a temperature of 20 ° C
m plate-shaped test pieces were prepared.

The evaluation of color and the evaluation of antibacterial activity were performed as follows. Measurement of color: Measured with AUCOLOR-7x (manufactured by Kurabo Industries, Ltd.). Antibacterial activity test: A test piece for antibacterial activity test of 4 cm x 4 cm was cut out from a plate-like test piece, 0.5 ml of a solution containing Escherichia coli was dropped on the test piece, covered with a sterilized polyethylene film, and wet at 35 ° C for 24 hours. After standing in this state, the number of bacteria was measured.

[Examples 1 to 3, Comparative Examples 1 to 3]
A salicylic acid derivative, an antioxidant, and the like were added to the resin, mixed well, and then a 5 cm × 9 cm plate-shaped test piece was prepared using an injection molding machine set at a temperature of 220 ° C. Table 1 shows the formulations and test results.

[0046]

[Table 1]

From the comparison between Comparative Example 1 and Examples 1 and 2 and Comparative Example 2 and Example 3 in Table 1, it is found that the salicylic acid derivative having a 1,2,4-triazole ring suppresses browning of a resin derived from an antibacterial agent. It was found to have the ability. This property was found to be remarkable in the polypropylene resin. Also, from a comparison between Comparative Example 2 and Example 3, it is found that the salicylic acid derivative having a 1,2,4-triazole ring is effective in preventing discoloration due to a partial reduction in color unevenness due to partial discoloration in the ABS resin. Do you get it. From the results of Comparative Example 4 and Example 2, it was found that the addition of an appropriate amount of the discoloration inhibitor was effective for improving the antibacterial properties, but that an excessive addition inhibited the antibacterial properties.

[Examples 2, 5, 6 and Comparative Examples 1, 6, 7]
Further, with the same composition as in Comparative Example 1 and Example 2, the temperature of the injection molding machine was set to 220 ° C. (Comparative Example 1 and Example 2), and 240
C. (Comparative Example 6, Example 5) and 260 ° C. (Comparative Example 7, Example 6), and a 5 cm × 9 cm plate-shaped test piece was prepared. The color difference ΔE was measured for Examples 5 and 6, with Example 2 being 0 (reference 2), and with Comparative Example 1 being 0 (reference 1). Also, antibacterial properties were measured in the same manner as in Table 1,
The results are shown in Table 2.

[0049]

[Table 2]

In Examples 2, 5, and 6 in which the salicylic acid derivative having a 1,2,4-triazole ring was added, the color difference ΔE of the obtained molded product was small even when the molding temperature was increased.
It was revealed that the discoloration prevention effect was superior to that of the comparative example.

After exposing the injection molded products obtained in Comparative Example 1 and Example 2 to a sunshine weather meter having a black panel temperature of 63 ° C. for 100 hours or 200 hours,
The color difference ΔE was measured by setting Comparative Example 1 before exposure to 0 (Reference 1) and Example 2 to 0 (Reference 2), and comparing the degree of discoloration due to light rays. Table 3 shows the results.

[0052]

[Table 3]

Even after exposure for 100 or 200 hours, the discoloration of Example 2 was suppressed more than that of Comparative Example 1.

[0054]

The antibacterial resin composition of the present invention has advantages such as excellent color stability in the molding process, and a long initial color under actual use conditions and excellent aesthetics. Improve the value of molded products and provide ease of use. These antibacterial resin compositions include toothbrushes, writing utensils, daily necessities such as kitchen supplies, fibers, OA equipment,
It can be used for plastic products such as home appliances, sheets and films. In addition, various paints, adhesives,
Can be added to adhesives, etc. to form coatings, general printed matter, interior and exterior wall paints for houses, etc., or as adhesives
It can be used as an adhesive for wallpaper.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) A01N 25/34 A01N 25/34 Z C08K 3/08 C08K 3/08 3/22 3/22 5/3472 5/3472 C08L 101/00 C08L 101/00 C09K 15/30 C09K 15/30 F-term (reference) 4H011 AA02 BA01 BA03 BA06 BB18 BC09 BC19 DA01 DC05 DG02 DH02 4H025 AA17 AA55 4J002 AC011 AC031 AC041 AC071 AC082 BB011 BB121 BB151 BB121 BB121 BB121 BB121 BB121 BB121 BB121 BB121 BB121 BB121BB101 BN151 CC161 CC181 CD001 CF031 CG001 CL001 DE106 EJ067 EU177 FB076 FD077 FD186

Claims (4)

[Claims] An antimicrobial agent comprising a mixture of zinc oxide coated with silver or a silver alloy and uncoated zinc oxide;
An antibacterial resin composition comprising a resin and a salicylic acid derivative having a 1,2,4-triazole ring. 2. The antibacterial resin composition according to claim 1, wherein the resin is a polyolefin resin polymerized by a polymerization catalyst containing a halogen element. 3. A salicylic acid derivative having a 1,2,4-triazole ring in an amount of 0.2 to 30% by weight based on an antibacterial agent comprising a mixture of zinc oxide coated with silver or a silver alloy and zinc oxide not coated. Antimicrobial composition added. 4. A molded article obtained from the antibacterial resin composition according to claim 1.