JPH01136663A - Manufacture of antibacterial molded item - Google Patents

Abstract

PURPOSE:To make molded items themselves have persistent antibacterial activity by blending watersoluble silver compound in cationic natural gum latex or cationic synthetic gum latex. CONSTITUTION:Natural gum latex is prepared by using a water solution containing various organic and inorganic substances as the dispersion medium and gum as the dispersion agent and by adding pH adjusting agent, vulcanizing agent, vulcanization accelerator, softening agent, filling agent, age resistor and coloring agent as needed. As cationic gum latex, single polymers of vinyl monomers or their copolymers may be enumerated. As an antibacterial agent, watersoluble silver compounds are used. Preferable water soluble silver compounds include silver salts and protein silver. As preferable examples of silver salts, silver nitrate and silver lactate can be enumerated. Protein silver is a compound consisting of protein and silver, preferably containing 7.5-8.5wt.% of silver. For preparation of molded item, straight method, coagulant dipping method, thermal sensitive dipping method and electrodeposition dipping method can be enumerated as examples.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing a molded product by a coating method, and more specifically, a method for manufacturing a molded product having antibacterial properties by a coating method. It is about the method.

(Prior Art) Examples of raw latexes used when manufacturing rubber products by coating methods such as dipping methods include natural rubber latex, chloroprene latex, and butadiene-styrene copolymer latex.

Natural rubber latex is made by adding 0.3 to 1.0% of ammonia as a normal preservative to the milky white sap that flows out when a rubber tree is cut.The composition of this latex is that of rubber carbonization. In addition to containing 35-40% hydrogen, it also contains about 2% protein, other small amounts of less than 1% fatty acids or their esters, sterols, complex lipids, sugars,
Consists of minerals, enzymes, etc. Therefore, in natural rubber latex, the amphoteric electrolyte protein contained in its components plays a role like a kind of protective colloid by adsorbing to the surface of rubber particles.

Helps stabilize floating dispersion of latex particles. ``In other words, since these rubber particles have a wax charge in the weakly acidic and alkaline regions, electrostatic repulsion occurs between the rubber particles and they are stably dispersed without agglomeration. Fresh latex is mostly a neutral (pH 7.0-7.2) and relatively unstable emulsion; that is, in tropical regions, when latex is exposed to air, it quickly turns rancid due to the action of bacteria; After 12 to 14 hours, the pH will reach about 5 and spontaneous coagulation will occur.This is because the latex aqueous phase contains substances that are extremely favorable for bacterial growth, such as proteins, salts, and sugars. This is because they reproduce extremely rapidly.Therefore, it is necessary to add an appropriate preservative as early as possible before rancidity progresses.

Ammonia is considered to be the most suitable preservative because it neutralizes acids and repels bacteria to prevent their proliferation. Since ammonia is usually added in an amount of 0.3 to 1.0%, the pH of the latex is at least 9 or higher, usually 10.
It is maintained at an alkaline level. JIS K is currently regulated as the Japanese Industrial Standard for natural rubber latex.
638H1982) was established along this line.

Usually, the compound latex used in the coating method is the raw material latex as described above, and if necessary, a vulcanizing agent, a vulcanization accelerator, a filler, and a softening agent.

It contains anti-aging agents, pH adjusters, etc. as appropriate, and these are maintained or adjusted to remain alkaline even after being blended. Therefore, the natural rubber latex commonly used at present is based on negatively charged anionic latex, and almost all of the various coated molded products are manufactured from these.

2 Examples of synthetic rubber latex include 2.

A homopolymer of vinyl monomers or a copolymer thereof.

Single polymer of diene monomer or its copolymer,
A copolymer of the above vinyl monomer and diene monomer,
Other functional groups include epoxide groups.

Amine group, carboxyl group, acid anhydride group, hydroxyl group.

Examples include those whose main component is a copolymer of a vinyl monomer having an amide group, an N-methylolamide group, an isocyanate group, etc., and the various monomers mentioned above.

Latex molding methods include coating methods such as dipping methods, casting methods, extrusion methods, foam rubber manufacturing methods, fiber surface processing methods, and fiber adhesion methods. In addition, there are special manufacturing technology problems as described below. In other words, the immersion molding method involves filling a dipping tank with latex, immersing the immersion mold in it, and then pulling it up to adhere the latex to the immersion mold. Since the amount of latex stored in the dipping tank is overwhelmingly larger than that in the dipping tank, the economic loss when the latex gels in the dipping tank is immeasurable.

Conventionally, the most effective method for imparting sustained antibacterial activity to medical devices has been to disperse antibacterial agents so that a certain concentration or higher of the antibacterial agent is retained in or on the surface of the substrate during the course of its use. The so-called =5= matrix device is considered as a system.

On the other hand, heavy metals such as gold, silver, copper, and zinc, as well as their metal compounds, are known to have strong bactericidal effects against microorganisms such as bacteria and fungi at extremely small concentrations in the form of metal ions. , is called oligodynamism.

Generally, silver compounds and silver salts have low solubility in water, so when they are blended into latex in a solution state, the silver concentration in the base material becomes very low. Furthermore, in order to increase the silver concentration in the base material, for example, silver nitrate, which has high water solubility, is added to the latex in the form of an aqueous solution, although the reason for this is not clear.

This destroys the system in which latex is stably suspended in an aqueous solution and causes aggregation, making it impossible to obtain a stable latex composition.

From the above-mentioned viewpoints, tools have been proposed that make use of the oligodynamism of the above metals, especially silver compounds, and have a metal body adhered to a base material, or that have metals dispersed or blended in the base material. has been done.

For example, in Japanese Patent Application Laid-Open No. 52-62996.

a metal body having oligodynamics on the surface of a flexible tube;
Alternatively, a catheter covered with a ring, net, etc. made of a metal body has been proposed. However, the operation of attaching a metal body to the surface of a molded catheter is extremely troublesome and complicated, and the production efficiency in actual manufacturing sites is low.

Also, in JP-A-59-218517.

The antimicrobial metal compound is ground into particles within 30 microns and then dispersed in a suspension capable of forming a catheter.

A method of curing to form a catheter with antimicrobial activity is described. However, 3 metal compounds
Prevents the pulverization process into particles with a size of 0μ or less and the re-agglomeration of the pulverized metal compound particles.

In order to maintain a stable particle state, it is necessary to add a so-called surfactant, which increases production costs.

In this way, in order to produce a molded product that itself has antibacterial properties using oligodynamism, the process of applying a metal body to the surface of the molded product after molding as described above or A process of pulverizing the metal compound into fine particles and dispersing it into a suspension is required, which results in two problems: low production efficiency (and increased production costs).

(Problems to be Solved by the Invention) An object of the present invention is to provide a method for producing an antibacterial molded product in which the molded product itself has continuous antibacterial activity.

Another object of the present invention is to provide a method for manufacturing antibacterial molded products industrially and with high productivity using simple operations.

Another object of the present invention is to provide a method for stably producing antibacterial molded articles using a coating liquid made of a latex composition containing a silver compound.

(Means for Solving the Problems) As a result of extensive research in order to achieve the above objectives, the inventors of the present invention have blended a water-soluble silver compound into cationic natural rubber latex or cationic synthetic rubber latex. As a result, a latex composition with excellent stability can be obtained, and the inventors have discovered that the intended purpose can be achieved by using this composition as a coating liquid, and have thus arrived at the present invention.

That is, the present invention is directed to manufacturing a molded product by a coating method using a coating liquid made of natural rubber latex or synthetic rubber latex.

The gist of the present invention is a method for producing an antibacterial molded article, which is characterized in that a latex composition in which a water-soluble silver compound is blended with a cationic natural rubber latex or a cationic synthetic rubber latex is used as a coating liquid.

The natural rubber latex referred to in the present invention is an aqueous solution containing various organic and inorganic substances that flows out when cutting the bark of a rubber plant as a dispersion medium.

The rubber component is used as a dispersoid, and if necessary, a pH 8m adjustment agent, extraction agent, vulcanization accelerator, softener, filler, and anti-aging agent.

It is latex mixed with coloring agents. Normal latex has a pH of 1! It is an anionic latex containing 0.3% by weight of ammonia as a conditioner and has a pII adjusted to 9-11. On the other hand, the cationic natural rubber latex used in the present invention is a so-called acidic latex having a pH of pi+4.7 or less, which is the isoelectric point of the protein which is a protective colloid, and preferably 3 or less.
In this state, the rubber particles have a positive charge opposite to that of normal natural rubber latex and are stabilized by repelling each other. To prepare such an acidic latex, 1. For example, 1. Add a cationic surfactant or a nonionic surfactant to the rubber content of normal natural rubber latex (solid content concentration 50-60%, pH 9-11). Add so that the amount is about 1 to 5% by weight.

Next, a suitable inorganic or organic acid may be added to adjust the pH to 3 or less. Hydrochloric acid and sulfuric acid are preferably used as inorganic acids, and formic acid, acetic acid, oxalic acid and the like are preferably used as organic acids.

Examples of the cationic synthetic rubber latex used in the present invention include ethylene, styrene, vinyl, vinyl chloride, and vinylidene chloride.

Acrylonitrile, (meth)acrylic acid ester.

A homopolymer of vinyl monomers such as vinyl pyridine and methyl vinyl ether, or a copolymer thereof.

Butadiene, isoprene, 1,3-pentadiene.

A homopolymer of diene monomers such as 1,5-hexadiene, 1,6-hebutadiene, and chloroprene, or a copolymer thereof, a copolymer of the above-mentioned vinyl monomer and diene monomer, and other functional groups such as epoxide groups, Amino group, carboxyl group, acid anhydride group, hydroxyl group, amide group,
Examples include copolymers of vinyl monomers having N-methylolamide groups, isocyanate groups, etc., and the various monomers listed above, which are blended with cationic surfactants as emulsifying and dispersing agents. Depending on the situation, nonionic surfactants, crosslinking agents, fillers, softeners, etc. may be added.

In the present invention, a water-soluble silver compound is used as an antibacterial agent. Suitable water-soluble silver compounds include silver salts and protein silver. Silver salt means a salt formed between silver and an inorganic or organic acid. Preferred specific examples of silver salts include silver nitrate, silver lactate, silver chlorate, silver fluoride, and silver picrate. Protein silver is a compound of protein and silver, and preferably contains 7.5 to 8.5% by weight of silver listed in the Japanese Pharmacopoeia.

Water solubility in the present invention means that the solubility in 100 g of distilled water at 20°C is 1.0 g or more, preferably 5.0 g.
It means 8 or more.

The preferred amount of the water-soluble silver compound varies depending on the purpose and the type of silver compound used, but for boat fishing, 0.1 to 30% by weight of silver based on the solid content of latex
In particular, it is preferably 0.5 to 10% by weight. When the amount is more than 30% by weight, the strength of the molded product obtained therefrom tends to be poor, while when it is less than 0.1% by weight, antibacterial performance becomes difficult to exhibit, which is not preferable.

The method for preparing the coating liquid in the present invention is not particularly limited as long as each component is mixed uniformly, and various known methods can be used. For example, a method is preferably employed in which an aqueous solution of a water-soluble silver compound, particularly preferably an aqueous solution with a high concentration of a water-soluble silver compound, is directly added to the latex.

Any conventionally known method may be used to produce a molded article by the method of the present invention. for example.

The immersion methods include the straight method, adhesive immersion method (anodic method or Teague adhesive method), and thermal immersion method.

Examples include electrodeposition immersion method. As a specific example,
When manufacturing urinary catheters made of natural rubber, since urinary catheters are usually made from natural rubber latex by dip molding, which is a coating method, natural rubber containing the above-mentioned aqueous silver compound is used as the coating liquid. By specially preparing the rubber latex composition, it can be manufactured using exactly the same manufacturing method as conventional methods. Also.

When using other synthetic rubber latex compositions as the coating liquid, similarly, a semi-finished product made of the same type of base material or a different type of base material is immersed in the coating liquid, or the coating liquid is sprayed onto the semi-finished product. It can be manufactured by a so-called coating method.

(Examples) Hereinafter, the present invention will be explained in more detail by giving examples.

Note that "part" in the two examples means "1 part by weight."

Example 1 Acidic natural rubber latex with a solid content concentration of about 60% by weight (
0.4 parts of zinc dimethyldithiocarbamate, 1 part of sulfur, 2.5 parts of zinc white, and 1 part of stearic acid are uniformly dispersed in 100 parts of pH 2.8) to create a blended latex (hereinafter referred to as , referred to as Solution A) was prepared. Add to 100 parts of the above solution A.

When 10 parts of a silver nitrate aqueous solution (10% by weight) was added with stirring, the latex did not coagulate, and a coating liquid (silver 1.1wt%) in which silver nitrate was uniformly dispersed could be obtained.

Using the obtained coating liquid, we carried out continuous production on an industrial scale by replenishing the amount lost on the day in a urinary catheter manufacturing device using the normal dip molding method. The latex contained therein did not form any agglomerates, and a urinary catheter of constant quality could be stably manufactured.

Regarding the obtained urinary catheter, the following method was used:
Antibacterial activity test I.

That is, cut the resulting urinary catheter.

The section was washed with a 70% ethanol aqueous solution in a sterile environment, the ethanol was dried and distilled off, and then placed on the bottom of a sample bottle with the inner surface facing upward. Next, 200 μl of E. coli cultured in trypticase soy broth at 37°C overnight was placed on the inner surface of the section, and after sealing, the culture was incubated at 37°C for 1 hour.
It was cultured for 8 hours.

Then, add 0.1% surfactant (Twee) to the sample bottle.
Physiological saline containing n80 (Issha Sangyo) was added to collect the bacterial solution, and the number of viable bacteria was measured by colony counting method.

As a control, the same procedure as above was performed except that the bacterial solution was placed directly at the bottom of the sample bottle.

As a result, the number of bacteria recovered was 0.7% of the control.

In addition, the urinary catheter of Example 1 was immersed in water at room temperature for one week, dried, and then subjected to an antibacterial activity test using the same method as described above.The number of bacteria recovered was 2.5 times that of the control. It was 2%.

Comparative Example 1 To 100 parts of anionic natural rubber latex having the same composition as the above liquid A and having a pH of 10.0, a silver nitrate aqueous solution (10% by weight) was added.
) was added with stirring, the blended latex suddenly increased in viscosity and many small agglomerates were formed.

Using the obtained coating liquid, an attempt was made to manufacture a urinary catheter in the same manner as in Example 1, but due to the increase in the viscosity of the latex and the formation of a large number of aggregates, it was difficult to make a urinary catheter with a uniform surface texture. could not be manufactured.

Example 2 Example 1 except that 30 parts of brothin silver aqueous solution (20 wt%) was used instead of 10 parts of silver nitrate aqueous solution (10 wt%).
When urinary catheters were continuously produced in the same manner as above, even after one month, the latex in the dipping tank did not form any agglomerates, and urinary catheters of constant quality could be stably produced.

The obtained urinary catheter was subjected to an antibacterial activity test using the same method as in Example 1.

The number of bacteria recovered was 2.3% of the control.

Example 3 Continuous production of urinary catheters was carried out in the same manner as in Example 1 except that 10 parts of silver picrate aqueous solution (5 wt%) was used instead of 10 parts of silver nitrate aqueous solution (10 wt%).1
The latex in the soaking bath did not form any agglomerates even after the test, and urinary catheters of constant quality could be stably manufactured. The obtained urinary catheter was subjected to an antibacterial activity test using the same method as in Example 1, and the number of bacteria recovered was 6.8% of the control.

(Effects of the Invention) According to the present invention, a latex composition in which a water-soluble silver compound is blended with a cationic natural rubber or a cationic synthetic rubber latex can be produced on a normal production line without requiring special devices or advanced techniques. Just by incorporating it, antibacterial molded products with continuous antibacterial activity can be stably and continuously produced on an industrial scale, and its industrial significance is extremely large.

According to the present invention, it is possible to produce molded products such as 1. medical equipment, sanitary tools, 2. food manufacturing equipment or equipment, etc., which have antibacterial properties that last even during long-term use.

Specific examples of such molded products include catheters such as urinary catheters, surgical gloves and other gloves, hand cots, l'i'Ii milk bottle nipples, ice banks used by patients in hospitals, Examples include hangs such as urine storage hangs, fluid supply and drainage tubes, and sponges. These have antibacterial agents on their surfaces and are extremely effective in preventing infections from bacteria and fungi.

=18-

Claims (3)

[Claims] (1) When manufacturing molded products by the coating method using a coating liquid made of natural rubber latex or synthetic rubber latex, a water-soluble silver compound is blended with the cationic natural rubber latex or cationic synthetic rubber latex as the coating liquid. A method for producing an antibacterial molded article, characterized by using a latex composition. (2) The manufacturing method according to claim 1, wherein the water-soluble silver compound is silver nitrate. (3) The manufacturing method according to claim 1, wherein the water-soluble silver compound is protein silver.