JPH06343690A - Manufacture of anti-bacterial rubber - Google Patents

Abstract

PURPOSE:To provide a method to impart anti-bacterial property to a rubber for use as different types of medical material by forming a metallic silver film having a uniform and flat surface on the rubber strongly and stably by the chemical plating method without impairing the softness of the rubber. CONSTITUTION:A surface washing process is applied to a rubber material by the use of a solution with reducing agent, followed by treatment with glyoxal and then a treatment with ammoniac silver nitrate solution, and further a treatment is made if necessary with an aqueous solution of a metal chloride, and thereby an anti-bacterial rubber covered with silver lining is manufactured.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing an antibacterial rubber by silver coating.

[0002]

2. Description of the Related Art A method of reacting an ammoniacal silver nitrate solution and glyoxal to coat the rubber surface with silver is already known, as described in JP-A-2-200269.

However, in the conventional method, there are cases where a part not covered with the silver film is formed, or a part of the silver covered is black, and the part not covered with the silver film and the blackened silver film are not formed. However, since it does not show an antibacterial effect, it is practically problematic as an antibacterial rubber. In addition, the nonuniformity of the silver coating may damage the mucosal tissue when used as a urinary tract catheter that requires long-term contact with vulnerable mucosal tissue, etc. May occur and the desired antibacterial effect may not be obtained.

Further, when the coating treatment is carried out by the conventional method, the surface of the silver coating is likely to have a cloudy color, and a smooth surface showing a so-called metallic luster may not be formed. When used for applications such as urinary tract catheters as described above, it is considered necessary to form a silver surface as smooth as possible so that mucosal damage is unlikely to occur, and in that respect also the conventional method has a problem. is there.

[0005]

As described above, in order to impart antibacterial properties to the surface of rubber, it is necessary to uniformly coat the entire surface with a clean silver coating which is not blackened. For this purpose, in the conventional method, it was necessary to increase the amount of coated silver to perform the entire coating, or to repeat the silver coating treatment several times. However, if the amount of coated silver is increased, the silver coating becomes thicker, and the silver coating is liable to chip off when the rubber is deformed or comes into contact with another object. This can be a fatal drawback, especially when used as a urinary catheter. Further, repeating the treatment is not a practical method in industrial production.

Further, a simple and practical method for producing a smooth silver-coated surface has not heretofore been known. Therefore, it has been desired to develop a simple method for coating rubber with a silver coating that is uniform and does not include a black portion and has a smooth surface to impart antibacterial properties.

[0007]

Means for Solving the Problems As a result of intensive investigations by the present inventors, the rubber was treated with glyoxal and then with an ammoniacal silver nitrate solution after surface-cleaning the rubber with a reducing agent solution. It has been found that by coating the surface with silver, an antibacterial rubber coated with a silver coating that is uniform and does not contain black portions can be produced.

Furthermore, the present inventors can produce an antibacterial rubber coated with a silver coating having a more excellent metallic luster by coating the surface of the rubber with silver and then treating it with an aqueous solution of a metal chloride. I found it.

The present invention has been completed based on the above findings. That is, the present invention is characterized in that (1) a rubber is subjected to a surface cleaning treatment using a reducing agent solution, then treated with glyoxal, and then treated with an ammoniacal silver nitrate solution to coat the rubber surface with silver. Antibacterial rubber manufacturing method,

(2) A method for producing an antibacterial rubber according to claim 1, wherein the rubber surface is coated with silver and then treated with a metal chloride aqueous solution.

According to the method of the present invention, not only natural rubber but also chloroprene rubber, nitrile butadiene rubber, butyl rubber, acrylic rubber, silicone rubber and the like can be treated in the same manner.

Further, according to the method of the present invention, it is possible to coat the rubber with a silver coating which is uniform and does not contain a black portion and which has a smooth surface having a metallic luster. Regardless of the shape of the rubber coated with silver, all rubber products such as plates, strings, and tube-shaped rubber can be coated with silver. Further, since the silver coating layer according to the method of the present invention is sufficiently firmly bonded to rubber, it has sufficient durability against deformation such as bending and slight friction.

As a result, even when used as a urinary tract catheter, the silver coating is not peeled off, and it is sufficiently durable for use. When using a urinary tract catheter, there is a problem that "ascending infection" often occurs, and development of a catheter having an antibacterial effect has been long awaited. A so-called biofilm formed by bacteria adhering to the urinary tract catheter surface is considered as one of the causes of urinary tract stones adhering to the catheter surface. There is a high risk of damaging the urinary tract mucosa during desorption, and for this reason also the development of a catheter having an antibacterial effect has been long awaited. According to the method of the present invention, not only the outer surface of the urinary tract catheter but also the surface of the inner tube can be coated with silver, so that the retrograde of bacteria from the urine storage bag can be prevented. The total length of the urinary tract Foley catheter is generally about 42 cm, but it is not necessary to cover the entire length with silver. By coating with, it is possible to prevent infection by microorganisms.

Since the antibacterial rubber produced by the method of the present invention has the above-mentioned characteristics, it can be used as a medical instrument such as a urinary tract catheter as well as a rubber tube used in a food production process. It can also be used for various purposes such as a rubber hose attached to the end of a water faucet.

The present invention will be described in detail below. As the rubber, various kinds of rubber such as natural rubber, chloroprene rubber, nitrile butadiene rubber, butyl rubber, acrylic rubber and silicone rubber can be used. The rubber is preferably degreased with an organic solvent such as acetone and then subjected to a surface cleaning treatment with a reducing agent solution. As the reducing agent used at this time, hydrazine, formalin (alkaline aqueous solution) and the like can be used, but hydrazine is preferable. It is preferable to use hydrazine in the form of an aqueous solution of hydrazine hydrate from the viewpoint of removing the residue. The reducing agent solution is preferably an aqueous solution of a reducing agent.

The concentration of the reducing agent solution, the treating temperature with the reducing agent solution, the treating time, etc. differ depending on the type of rubber used and the type of reducing agent, but are usually 0.5 to 5% by weight.
A reducing agent solution having a concentration of
The rubber to be treated is immersed in the reducing agent solution at 35 ° C. for 1 to 30 minutes, particularly preferably 5 to 15 minutes, to react. The amount of the reducing agent solution used is not particularly limited, but it is necessary to immerse the rubber so that the treated surface of the rubber does not come into contact with the container wall containing the solution or other rubber, and the rubber surface to be treated is A sufficient amount of liquid is required to fully immerse the solution in this state. When the treatment with the reducing agent solution is completed, the rubber is pulled out of the solution, thoroughly washed with water, and then dried.

Next, glyoxal is attached to the surface of the rubber to be treated. The adhesion can be carried out by various methods. For example, a solution of glyoxal (for example, acetone solution) may be applied to the surface of the rubber, but simply by immersing the rubber in the acetone solution of glyoxal and then pulling and drying it. good. The concentration of the glyoxal solution used at this time is preferably 5 to 40% by weight, particularly preferably 1
It is 5 to 30% by weight.

Next, a silver film is formed by a reaction with an ammoniacal silver nitrate solution. The ammoniacal silver nitrate solution can be prepared from silver nitrate and aqueous ammonia by a known method. That is, it can be prepared by gradually adding aqueous ammonia to an aqueous solution of silver nitrate and terminating the addition of aqueous ammonia at the point where the initially formed precipitate is just dissolved. Although the concentration of the ammoniacal silver nitrate solution varies depending on the intended thickness of the silver coating, etc., the concentration of silver nitrate is generally preferably 0.1 to 5% by weight, and particularly preferably 1 to 3% by weight.

The ammoniacal silver nitrate solution thus prepared is placed in a container, and the surface of the rubber treated with glyoxal as described above on which silver is coated is dipped in the ammoniacal silver nitrate solution. At this time, it is preferable to immerse the solution as gently as possible so that the solution does not shake.

The temperature of the ammoniacal silver nitrate solution is preferably 35 ° C. or lower, particularly preferably 0 to 15 ° C. The immersion time depends on the desired thickness of the silver coating and the processing temperature, but about 5 minutes after the processed surface is immersed in the solution is sufficient. When the treatment is complete, the rubber is pulled out of the solution and washed with water until there is no residual ammoniacal silver nitrate solution.

After that, the rubber is treated (washed) by immersing the rubber in an aqueous solution of metal chloride to form a smooth silver coating having a metallic luster. As the metal chloride, any of sodium chloride, potassium chloride, magnesium chloride, calcium chloride, lithium chloride and the like can be used, but it is preferable to use sodium chloride (salt) considering the purity and price of the commercially available compound. .

The concentration of the aqueous chloride solution of the metal used varies depending on the immersion time and temperature, but is usually preferably 5 to 15%. Further, the immersion time is sufficient for about 5 seconds to 1 minute at room temperature, but it is preferable to adjust it by visually observing the state of metallic luster.

Then, the rubber is pulled out from the aqueous metal chloride solution, thoroughly washed with water, and dried to obtain an antibacterial rubber coated with a smooth silver film having metallic luster. The antibacterial effect of the antibacterial rubber produced by the present invention against various bacteria is confirmed by a halo test method using an agar medium, or a shake flask method in which a suspension of bacteria is put in a flask and the antibacterial rubber is added and shaken. You can do it.

Since the antibacterial rubber produced by the method of the present invention is coated with a silver coating, it is necessary to use a contrast agent especially when performing fluoroscopy when using it as a catheter for indwelling urinary tract. Absent.

Since the antibacterial rubber produced by the method of the present invention has electric conductivity due to the surface coating, it can be used as an electrode having characteristics such as flexibility, deformability and elasticity. .

[0026]

EXAMPLES The present invention will now be described more specifically by showing examples, but the present invention is not limited to these examples.

Example 1 A surface of a natural rubber plate having a length and width of 10 cm and a thickness of 2 mm to be subjected to silver coating was washed with acetone, degreased and dried. Hang this rubber plate with nylon thread and
It is immersed in an aqueous solution of hydrazine hydrate for 10 minutes to carry out reduction cleaning (surface cleaning treatment). Pull the rubber plate out of the solution,
It is washed with water, the aqueous hydrazine hydrate solution is washed off, and then dried.

500 g of a 40% aqueous glyoxal solution and 500 g of acetone are mixed and dissolved. A rubber plate that has been subjected to reduction cleaning is dipped in this solution, pulled up, and dried by ventilation.

2% ammonia water was added dropwise to a 1% silver nitrate aqueous solution with stirring, and when the initially formed precipitate was dissolved, the addition of ammonia water was stopped to prepare an ammoniacal silver nitrate solution. The ammoniacal silver nitrate solution thus prepared is placed in a container and the liquid temperature is kept at 5 ° C. The surface of the rubber plate which has been subjected to the glyoxal treatment as described above and which requires silver coating is immersed in this solution. At this time, the surface where silver coating is required is performed gently so as not to touch the wall of the container, and after being kept as it is for 3 minutes, it is taken out of the solution and sufficiently washed with water until the ammoniacal silver nitrate solution remains.

The silver-coated rubber plate thus obtained is immersed in a 10% saline solution for 1 minute, then pulled up and washed with water to obtain an antibacterial rubber plate. The surface of the silver coating formed on the antibacterial rubber plate is a smooth silver coating having no black portion and excellent metallic luster, and firmly adheres to the rubber.

Example 2 A natural rubber Foley catheter having an outer diameter of about 6 mm was washed with acetone, degreased, and dried. Suspend this catheter, 1% by weight from the tip to about 30 cm
It is immersed in an aqueous solution of hydrazine hydrate for 10 minutes for reduction cleaning. The catheter is pulled up from the solution, washed with water, the aqueous hydrazine hydrate solution is washed off, and then dried.

500 g of 40% glyoxal aqueous solution and 300 g of acetone are mixed and dissolved. A catheter that has been subjected to reduction cleaning is dipped in this solution, pulled up, and dried by ventilation.

To 200 g of a 5% silver nitrate aqueous solution, 5% ammonia water was added dropwise with stirring, and when the precipitate formed first dissolved, the ammonia water addition was stopped, and finally water was added to bring the total amount to 500 g. Prepare an ammoniacal silver nitrate solution. The ammoniacal silver nitrate solution thus prepared is placed in a cylindrical container, and the liquid temperature is kept at 3 ° C. Insert the glyoxal-treated catheter from the tip 25
Immerse in this solution up to cm. At this time, the catheter is gently moved so as not to touch the container wall, kept for 2 minutes as it is, taken out of the solution, and thoroughly washed with water until the ammoniacal silver nitrate solution remains.

The thus obtained silver-coated catheter was immersed in 10% saline for 1 minute, then pulled up and washed with water to obtain an antibacterial catheter. The surface of the silver coating formed on the antibacterial catheter has no black part at all,
It has a smooth silver coating with excellent metallic luster and firmly adheres to rubber. Further, a silver coating is formed on the surface of the inner tube of the antibacterial catheter, like the outer surface.

Test Example Next, the antibacterial effect of the antibacterial rubber produced by the method of the present invention will be described with reference to test examples.

Test Examples 1-2 Antibacterial Effect Test by Hello Test Method A part (test piece) of the antibacterial rubber plate and the antibacterial catheter produced in Examples 1 and 2 was placed in the center of an ordinary agar medium.
Place it so that half of the antibacterial rubber is buried, and then E. coli (IFO 330
1) The suspension was applied uniformly. Further, substantially the same amount of the same rubber that had not been subjected to the silver film formation treatment was used in the test as a control product in the same manner as the test piece. After culturing for 24 hours in a 35 ° C. incubator as it was, a clear halo with a substantially uniform width was observed around the silver-coated surface of the antibacterial rubber.
Since no halo was observed in the control product,
It has been proved that the antibacterial rubber has a sufficient antibacterial effect.

Test Examples 3 to 4 Antibacterial Effect Test by Shake Flask Method Sampling was performed so that the surface area of the silver coating of the antibacterial rubber produced in the above Examples 1 and ² was 12 cm ² , and finely cut to be used as a test piece. I was there. In addition, approximately the same amount of the same rubber that had not been subjected to the silver film formation treatment was used in the test as a control product in the same manner as the test piece. 3 with nutrient broth
Escherichia coli (IFO 3301) cultured at 0 ° C. for 1 day was diluted 150-fold with a phosphate buffer to prepare a test bacterial solution. The viable cell count in the test bacterial solution at this time is 4 to 5 × 10 ⁷ cells / ml.
Met. 75 ml of this test bacterial solution and the above test piece or control product were added to a flask and shaken horizontally at a rate of 100 times / minute for 1 hour. The viable cell count before and after shaking was determined by the dilution plate method, and the reduction rate (bacterial reduction rate) of viable cell count due to shaking was calculated.
That is, the sterilization rate was calculated by the following formula. Sterilization rate (%) = 100 × (the number of viable cells before shaking-the number of viable cells after shaking) / the number of viable cells before shaking The test results by the shake flask method are shown in Tables 1 and 2 below.

[0038]

[Table 1] Table 1 Results of antibacterial effect test by shake flask method of antibacterial rubber plate (Example 1) Samples Number of viable bacteria before shaking Number of viable bacteria after shaking Sterilization rate (pieces / ml) (pieces / ml) (% ) control sample ^{4.3 × 10 7 4.6 × 10 7} - 7 antimicrobial rubber plate ^{4.0 × 10 7 7.1 × 10 6} 82

[0039]

[Table 2] Table 2 Results of antibacterial effect test by shake flask method of antibacterial catheter (Example 2) Samples Viable bacteria before shaking Viable bacteria after shaking Sterilization rate (cells / ml) (cells / ml) (%) Control product 4.3 × 10 ⁷ 4.5 × 10 ⁷ −5 Antibacterial catheter 4.4 × 10 ⁷ 7.6 × 10 ⁶ 83

As is clear from Tables 1 and 2 above, the antibacterial rubber produced by the method of the present invention exhibits an excellent antibacterial effect. Although the shaking time was set to 1 hour in this test, the antibacterial effect was further clarified when the shaking time was further increased. Using an antibacterial catheter as a sample, 2
When shaken for 4 hours, the sterilization rate was 99% or higher.

[0041]

The rubber coated with a smooth and uniform silver film having metallic luster by the method of the present invention exhibits an excellent antibacterial effect and can be used as a medical instrument such as a urinary tract catheter and food It can be used in various applications such as rubber tubes used in the manufacturing process and rubber hoses attached to the ends of taps. Further, since the silver coating layer is firmly bonded to rubber, it has sufficient durability against deformation such as bending and slight friction. Further, when used as a catheter for indwelling the urinary tract or the like, a contrast agent is not particularly required even when performing fluoroscopy. Further, the rubber coated with the silver coating, which is produced by the method of the present invention, has electric conductivity due to the surface coating, and thus can be used as an electrode having characteristics such as flexibility, deformability and elasticity. Is.

Claims (2)

[Claims] 1. An antibacterial rubber characterized by subjecting a rubber to a surface cleaning treatment using a reducing agent solution, followed by treatment with glyoxal and then with an ammoniacal silver nitrate solution to coat the rubber surface with silver. Manufacturing method. 2. The method for producing an antibacterial rubber according to claim 1, wherein the surface of the rubber is coated with silver and then treated with a metal chloride aqueous solution.