JP4180922B2 - Antibacterial rubber composition - Google Patents

Description

  The present invention relates to non-silicone unvulcanized and / or vulcanized raw rubber compositions (or final made from such unvulcanized compositions) that contain silver-based compounds to provide highly desirable long lasting antimicrobial properties. Vulcanized rubber article). Such a composition is vulcanized to give a solid or foamed (foam or sponge) rubber article that can be utilized in a variety of different applications (including multi-layer composites) including such antimicrobial rubbers. The Since silver-based compounds are adversely affected by the use of standard vulcanizing agents and accelerators, such as sulfur-based compounds and / or systems, it is not possible to provide such an effective antimicrobial vulcanized rubber article. It is quite difficult. However, the present invention is like inorganic and organic peroxides and oxides that allow vulcanization and do not add reversibly bind silver ions, thereby resulting in long lasting antimicrobial properties of the final rubber article itself. And the presence of different non-sulfur based vulcanization systems and vulcanizing agents. Raw or vulcanized rubber compositions unexpectedly improve the control of antibacterial efficacy in rubber articles, while at the same time providing final rubber articles with dimensional stability, rigidity, flexural modulus, tensile strength, wear resistance, elongation. In order to provide desirable properties such as, fillers may also be included and plasticizers may also be included.

All US patents cited below are incorporated herein by reference in their entirety.
In recent years, considerable attention has been paid to the dangers of bacterial contamination from potential daily exposure. Notable examples of this are food poisoning by strain Eschericia coli found in beef that has not been cooked enough in fast food stores, diseases caused by Salmonella enteritidis contamination from uncooked filthy chicken products, Includes fatal consequences of diseases and skin infections caused by Staphylococcus aureus, Klebsiella pneumoniae, yeast (Candida albicans) and other unicellular microorganisms. As consumers interested in this area increased, manufacturers began to introduce antimicrobial agents into various everyday products and articles. For example, certain brands of cutting boards, insoles, medical devices and instruments, liquid soaps, etc. often contain antimicrobial compounds. The most popular antibacterial agent for such articles is triclosan. The compounding of such compounds in liquids or certain polymerization media has been carried out, but little has been applied to other substrates, especially vulcanized rubber and its surface. For example, triclosan itself is not durable because it readily diffuses into and out of the polymerized substrate and / or substrate. Furthermore, triclosan lacks the desired thermal stability for plastic processing at high temperatures and does not provide a broad range of bacterial sterilization. For example, triclosan does not show bactericidal properties against Pseudomonas aeruginosa.

  Antibacterial raw rubber compositions are undoubtedly strongly desired for vulcanized rubber article manufacture to provide not only antibacterial action but also antifungal, antifungal, antifouling and odor control properties. Rubber articles include cars (hoses, tires, bumpers, etc.), food processing equipment (conveyor belts, wheels, tubes, gaskets), household goods (toys, sinks, gaskets, electric / gas equipment, rubber door mats, rubber floor mats) , Carpeted floors or door mats, gloves, etc.), used in many different applications, including essentially all rubber applications where fungal and fungal growth is a potential problem. There is a long-standing need to provide an effective durable and reliable antimicrobial vulcanized rubber composition that provides an antimicrobial and / or antifungal effect that lasts for a long time in the final vulcanized rubber article. It remains. Unfortunately, the silver-based antibacterial-containing antibacterial raw rubber composition and / or vulcanized rubber article thus strongly desired has not been provided by the related prior art.

  The closest technology includes Japanese Patent Application 1997-342076 which discloses the production of unvulcanized rubber compositions and articles that exhibit antimicrobial properties due to the presence of silver composites. Such compositions are made by high temperature kneading in an oxygen free atmosphere and are used as parts in water disinfection systems. Also, vulcanized rubber is not taught or obtained in this publication. The antibacterial rubber band is vulcanized with a silver antibacterial agent therein and is taught in Japanese Patent Application 1997-140034. However, such compounds are considerably limited in use and must contain a sulfur vulcanizing agent in the vulcanization process in order to achieve the final vulcanizate of the subject rubber. Such sulfur vulcanizing agents have a significant adverse effect on silver-based antimicrobial agents, where sulfur reacts with silver ions to form silver sulfide and render it ineffective as a bactericidal agent. Thus, the use of such specific rubber band compositions for large scale antimicrobial articles and in articles is basically unfeasible.

  Certain antibacterial peroxide-catalyzed vulcanized rubber compositions have been produced so far; however, such peroxide vulcanized rubbers have all been silicone-based. It is well understood and appreciated that silicone rubber cannot be vulcanized with typical sulfur-based catalysts. Accordingly, the antimicrobial rubber compositions of US Pat. No. 5,466,726 and Japanese Patent Applications 1997-026273 and 1995-065149 are standard vulcanized silicone rubber compositions and articles containing certain antimicrobial compounds.

  Further, rubber latex (unvulcanized) containing an antimicrobial agent is disclosed as a floor mat having a silver-based antimicrobial agent incorporated in a pile fiber component (eg, US Pat. No. 5,736,591), which is a pile fiber. In order to protect the antibacterial compound from attack by sulfur compounds, it has a non-antibacterial rubber backing cured by peroxide catalyzed vulcanization (Japanese patent applications 1993-3555168 and 1995-38991). To date, however, there are disclosures and suggestions for the production of non-silicone raw rubber compositions or vulcanized rubber articles made therefrom that exhibit superior antimicrobial properties due to the long-lasting effective use of silver-based antimicrobial compounds. Not. The present invention fills such voids.

  Accordingly, an object of the present invention is to provide a vulcanized non-silicone rubber article of the present invention that has sufficient antibacterial activity and structural integrity to withstand repeated use without loss of antibacterial effectiveness or modulus strength to a detectable level. To provide a substantially non-silicone antibacterial unvulcanized raw rubber composition. Another object of the present invention includes a vulcanizing agent and a vulcanization accelerator and does not adversely affect the antimicrobial activity of the final vulcanized rubber article (thus inevitably free of sulfur-based vulcanizing agents and accelerators). Finally, an antibacterial non-silicone unvulcanized rubber composition comprising a silver-based antibacterial compound is to be provided. Yet another object of the present invention is to provide a log kill rate of at least 1.0 after 24 hours exposure to Staphylococcus aureus and Klebsiella pneumoniae (and other types of fungi) at room temperature. It is to provide an unvulcanized non-silicone raw rubber composition that vulcanizes to form an antimicrobial non-silicone vulcanized rubber article. Yet another object of the present invention is to test at least 15 days at 30 ° C. and over 90% humidity according to test method ISO 486 for Aspergillus niger, Paecilomyces variotii and Trichoderma virens (and other types of fungi). And providing an unvulcanized rubber composition that vulcanizes to form an antimicrobial article exhibiting at least 70% inhibition. Still another object of the present invention is to provide a structurally integral filler component (eg, carbon black, silica, metal salt) that improves the control of the antibacterial effect of rubber articles by controlling the release of silver ions to the article surface. , Organic salts, metal oxides, and the like) and plasticizers (eg, phthalate oil, paraffin oil, etc.). Yet another object of the present invention is to provide a final article that exhibits increased antimicrobial activity after industrial cleaning and / or wear. Yet another object of the present invention is to provide an antibacterial dimensionally stable vulcanized rubber that can withstand repeated use and exhibits sufficient antibacterial activity and structural integrity without loss of detectable antibacterial or modulus strength. To provide an article (eg, containing EPDM, NBR or natural rubber).

  Yet another object of the present invention is to include a vulcanizing agent and not adversely affect the antibacterial activity of the final vulcanized EPDM, NBR or natural rubber article (thus inevitably containing sulfur-based vulcanizing agents and accelerators). It is to provide an antibacterial vulcanized EPDM, NBR or natural rubber article containing a silver based antibacterial compound. Yet another object of the present invention is to prevent Staphylococcus aureus and Klebsiella pneumoniae (and / or other types of fungi) after 24 hours exposure at room temperature after interfering with the growth of certain fungi after exposure for at least 15 days. And vulcanized EPDM rubber-containing articles that exhibit a log sterilization rate of at least 1.0. Yet another object of the present invention is to improve the control of the antibacterial effectiveness of the article itself by adjusting the release of silver ions to the article surface (eg, high log sterilization rate against Staphylococcus aureus and Klebsiella pneumoniae). , Also showing growth inhibition against Aspergillus niger), structural integrity filler components and plasticizers (eg, pigments such as silica, metal salts, organic salts, carbon black, calcium carbonate, paraffin oil, phthalate oil) , Vulcanized EPDM, NBR or natural rubber containing articles, including metal oxides). Yet another object of the present invention is to provide a final article that exhibits increased antimicrobial activity after industrial cleaning and / or wear. Yet another object of the present invention is to provide a simple process for producing such antimicrobial vulcanized EPDM, NBR or natural rubber containing articles.

Thus, the present invention comprises at least one rubber component selected from the group consisting of nitrile butadiene rubber (NBR), natural rubber and mixtures thereof , at least one silver-based inorganic antibacterial compound and at least one vulcanization catalyst compound. Including a non-silicone unvulcanized raw rubber composition, wherein the catalyst does not contain a detectable amount of a sulfur-based vulcanizing agent and / or a vulcanization-accelerating compound, and the rubber composition optionally comprises a blowing agent And at least one filler component. Such raw rubber compositions can be subsequently vulcanized to produce a resilient antimicrobial effective rubber article that exhibits dimensional stability in the presence of a substantially sulfur free vulcanizing agent. In addition, the present invention provides a dimensionally stable vulcanized rubber-containing article (eg, EPDM, NBR and / or natural) that exhibits a log sterilization rate of at least 1.0 each for Staphylococcus aureus and Klebsiella pneumoniae after 24 hours exposure at room temperature. Rubber base). The present invention also relates to a dimensionally stable vulcanization exhibiting antifungal properties that exhibit at least 70% inhibition in a test at 30 ° C., over 90% humidity, at least 15 days, according to test method ISO 486 for Aspergillus niger ATCC 6275. Includes rubber-containing articles. Furthermore, the present invention provides at least one selected from the group consisting of fillers (for example, carbon black, calcium carbonate, inorganic salts, organic salts, silica and mixtures thereof) and plasticizers (oils such as phthalate oil and paraffin oil). Such vulcanized rubber-containing articles comprising one silver ion release controlling additive are included. In addition, the present invention provides a rubber composition comprising unvulcanized rubber, at least one non-sulfur based vulcanizing agent and at least one silver based inorganic antibacterial compound, wherein the rubber composition is at a temperature of at least 150 ° C. And a method for producing a vulcanized rubber-containing article comprising a step of vulcanizing at a pressure of at least 3 bars. Here, the rubber composition does not substantially contain a sulfur vulcanizing agent and a vulcanization accelerator.

  The term “dimensional stability” is intended to include vulcanized rubber articles that can be handled structurally without collapsing into smaller parts. Accordingly, the article must exhibit a certain degree of structural integrity, be a rubber, and exhibit a certain degree of flexural modulus.

  Such specific antimicrobial non-silicone raw or vulcanized rubber compositions are not taught or explicitly suggested in the rubber industry or prior art. As noted above, the absence of detectable amounts of sulfur-based vulcanizing agents and accelerators persists in the final product for at least long-term against Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa and Eschericia coli Allows retention of a sufficient amount of silver antibacterial agent to provide log sterilization rates. Furthermore, primarily due to high costs, non-sulfur vulcanizing agents are not commonly used in vulcanized rubber compositions and articles. Thus, a combination of a non-sulfur vulcanizing agent (most preferably a peroxide vulcanizing agent) and a silver-based antimicrobial agent in an unvulcanized rubber composition for effectively forming an antimicrobial vulcanized rubber article. There is no teaching or clear suggestion regarding.

  In addition, although not required, in general and preferably, fillers and oils (eg, silica, carbon black, stearate, and phthalate and paraffin oils as fillers) are added to the vulcanized rubber article with flexural modulus and Required to provide both structural integrity. The rubber component alone generally does not exhibit adequate dimensional stability without such additives. Surprisingly, the presence of such additives also provides the ability to control silver ion release at the target article surface. While not intending to be bound by any particular scientific theory, fillers such as silica and oils such as paraffin oil (as an example) serve to incorporate moisture into the article, and thus from the interior of the article to the surface. It is thought to move silver ions. In such a situation, the rubber article exhibits improved silver release, so the presence of a higher amount of available surface silver ions can result in a high log sterilization rate against the bacteria. Other fillers, such as pigments (eg carbon black) and calcium carbonate (for example) are believed to exhibit the opposite behavior of keeping water out of the target article and thereby preventing the migration of silver ions to the article surface. It is done. Therefore, such a decrease in silver ion availability increases the long-lasting durability of the antimicrobial article. Virtually the actual antimicrobial efficacy of all rubber articles can be controlled by the presence of certain amounts of such generally desirable fillers and oils (some hydrophilic antistatic agents also behave the same as silica). . As a result, the necessary filler and / or oil components that are desirable to provide the dimensional elasticity and / or flexural modulus (and practical utility) of the final article serve two purposes not previously recognized in the rubber industry. Useful. Rubber articles can be manufactured with specific end uses in mind, depending on the desired persistence of antimicrobial activity with the addition of specific amounts of such additives. Moreover, such a target sustained antibacterial vulcanized article and its benefits have not been known or recognized in the rubber industry until now. These rubber components are hereinafter referred to as “silver ion release controlling additives”.

  As mentioned above, the term “rubber” refers to all standard rubbers that are vulcanized to provide dimensionally stable rubber articles. Specific types are shown below, but they have been used for many years and are generally well known and taught in the prior art. Such a rubber composition of the present invention, together with fillers necessary for reinforcement (for example, calcium carbonate, carbon black, silica and clay), accelerates the degradation period of the elastomer during compounding and processing (and flexural elasticity in the final article). It should also have a chemical plasticizer, giving rate characteristics. Optionally, a foaming agent can be added to the composition of the present invention to form a foam rubber type (eg, foam or sponge, closed cell).

Accordingly, the rubber component of the raw or vulcanized rubber composition of the present invention is selected from the group consisting of nitrile butadiene rubber (NBR), natural rubber and mixtures thereof . More expensive but potentially useful modified rubbers include hydrogenated NBR and carboxylated NBR. The presence of silicone rubber is undesirable in the compositions of the present invention, but the possibility of adding small amounts of certain unvulcanized rubber components remains without adversely affecting the overall antimicrobial rubber composition itself. Has been. Thus, up to 25% of the total weight of the composition may be silicone rubber. However, the majority of the rubber composition must be non-silicone rubber. Furthermore, the non-silicone rubber part must not have appreciable amounts of sulfur-based vulcanizing agent or residue (in the final article) and is therefore primarily non-sulfur-based compounds (eg, peroxides, metals Must be vulcanized by curing with oxides. The rubber component is present in an amount of about 10 to about 1,000 parts, more preferably about 50 to about 500 parts, and most preferably about 100 to about 200 parts of the total composition. Thus, in the intended unvulcanized rubber composition (and subsequently formed rubber article), the rubber represents about 25 to about 70% of the total composition (and article) in about 300 to 2,000 parts overall. Constitute. The rest includes additives such as fillers, oils, vulcanizing agents, desirable antibacterial agents, optionally blowing agents (more details are given below).

  The antimicrobial agent of the raw or vulcanized rubber composition of the present invention can be any standard silver-based compound. In contrast to organic types such as triclosan, such compounds do not exhibit low thermal stability and therefore remain in the target substrate or substrate at different temperatures. Thus, such antimicrobial agents are easier to control for the desired surface release, as described above. Such antimicrobial agents include, but are not limited to, silver salts, silver oxide, elemental silver, and most preferably ion exchangers, glasses and / or zeolite compounds. More preferred for this purpose are silver-based ion exchange compounds. The reason for this is the low level of discoloration and improved durability imparted to the final product by such compounds, the efficacy that such compounds impart to the final composition, and the manufacturing that is possible with such specific compounds. It is easy. Thus, the antimicrobial agents of the present invention are merely representative microorganisms, but can be of any type that provides the desired log bactericidal rate against the aforementioned Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli and Pseudomonas aeruginosa. Furthermore, such antimicrobial compounds must withstand high processing temperatures in order to be successfully incorporated into the non-sulfur (eg, peroxide) vulcanized rubber compositions of the present invention. Again, such antibacterial agents preferably comprise silver-containing ion exchangers, glasses and / or zeolite compounds. Most preferably, such compounds are silver-based ion exchange compounds, especially free of further organic bactericidal compounds (which results in the release of volatile organic compounds into the atmosphere during high temperature processing, etc. Absent).

  A preferred silver-based ion exchange material is an antibacterial silver zirconium phosphate available from Milliken & Company under the trade name ALPHASAN®. Such compounds are available at different silver ion concentrations and as a mixture with zinc oxide. Accordingly, different compounds having a silver ion concentration of about 0.01 to 10%, preferably about 3 to about 8%, and most preferably about 3, 3.8 and 10% of the total amount of components (eg, the total amount of silver ions and zirconium phosphate) Is possible. Other potentially preferred silver-containing solid inorganic antimicrobial agents in the present invention are silver-substituted zeolites obtained from Sinanen under the trade name ZEOMIC®, or silver-substituted glasses obtained from Ishizuka Glass under the trade name IONPURE®. And can be used in addition to or in place of the preferred species. Other possible compounds are, but are not limited to, silver-based materials obtained from DuPont with MICROFREE®, as well as those from Johnson Mathey with JMAC®.

  Generally, such antimicrobial compounds are present in the rubber composition in an amount of about 0.1 to 10%, preferably about 0.1 to about 5%, more preferably about 0.1 to about 2% by weight of the total weight of the rubber composition. Most preferably, it is added in an amount of about 0.2 to about 2% by weight.

  Furthermore, with respect to silver-based inorganic antimicrobial materials, antimicrobial rubber articles have been shown to be particularly suitable due to the desirable high levels of efficacy and durability required for such articles. Certain silver-based ion exchange compounds, such as the ALPHASAN® brand antibacterial agent available from Milliken & Company, have been shown to exhibit impressive biological efficacy (US Pat. No. 5,926,238, Toagosei Co., Ltd.) No. 5,441,717, US Pat. No. 5,698,229). After a period of time, alternative antibacterial compounds (eg triclosan, Microchek, OBPA, Zn-omadine) are first biodegraded under high processing temperatures, leaching into the surrounding environment and finally depleting the bactericidal activity Causes consumption of the agent. However, silver-containing ion exchangers, glasses and / or zeolite compounds do not have such drawbacks. Such antibacterial agents exhibit high temperature (> 1000 ° C.) stability, do not leach into the environment, and provide substantial amounts of trace action silver ions to provide the desired long durability.

  The antibacterial article of the present invention finally produced from the raw rubber composition of the present invention comprises at least one of the AATCC draft method or the method of JIS2 2801 entitled “Evaluation of antibacterial properties of hydrophobic fibers and solid substrates” According to, after 24 hours, good log sterilization rate is exhibited. Such good levels of log kill were tested by Staphylococcus aureus or Klebsiella pneumoniae and increased by at least 0.1 from baseline. In other words, if the log sterilization rate is greater than the log sterilization rate of an untreated rubber article (eg, no added solid inorganic antibacterial agent) (eg Suppose that it is at an acceptable level. Preferably, such a baseline increase in log sterilization rate is at least 0.3 and 0.3 respectively for S. aureus and K. pneumoniae, more preferably 0.5 and 0.5 respectively, most preferably 1.0 and 1.0 respectively. It is. Of course, the upper limit of such logarithmic sterilization rate is much larger than the standard value and is 5.0 at maximum (sterilization rate 99.999%). Of course, any intermediate rate is acceptable as well. However, as long as the measured value is better than the value for the relevant untreated rubber article, negative log sterilization rates are also acceptable in the present invention. In such a case, it is indicated that the antibacterial material present in the rubber article at least prevents the growth of microorganisms. In addition, such rubber articles exhibit similar log sterilization rates against other types of fungi, such as Pseudomonas aeruginosa and Eschericia coli.

  Very surprising with the present invention is the ability in the final article of the present invention made from the raw rubber composition of the present invention to impart antifungal properties as well as antimicrobial properties. Such versatility is rare with antibacterial compounds. However, without intending to be limited to a particular scientific theory, it is believed that silver ions, particularly silver ions that are abundant on the surface of the article, provide excellent antifungal properties at least against certain fungi. Accordingly, another aspect of the rubber composition of the present invention is at least for a mixture of such organisms, for example Aspergillus niger, and fungi comprising Aspergillus niger ATCC 6275, Paecilomyces variotii ATCC 18502, Trichoderma virens ATCC 9645. Provides sterilization durability for 15 consecutive days. Other compounds, such as zinc oxide, as an example, can be formulated into the subject unvulcanized rubber composition (and subsequent articles) to provide broader potential antifungal properties.

  Of great importance to the efficacy of the compositions of the present invention with respect to antibacterial and antifungal activities, harmful amounts of sulfur-based vulcanizing agents and vulcanization accelerators can reduce the raw rubber compositions (and vulcanized articles) ). As noted above, in the rubber composition and / or article thereof, sulfur reacts with the preferred silver-based antimicrobial agent and irreversibly binds silver ions (such as silver sulfide). Then, the resulting silver sulfides and the like are not effective as antibacterial agents, and therefore their presence renders the final product antimicrobially inactive. Accordingly, it has been necessary to produce vulcanized rubber articles that do not contain detectable amounts of sulfur vulcanizing agent and vulcanization accelerator. The term “detectable amount” should be understood to allow for the presence of small amounts. It has been found that a 1: 1 molar ratio of sulfur to silver (and higher) causes a clear loss of antimicrobial activity in the desired final vulcanized article. However, a higher molar amount of silver than sulfur imparts at least some antimicrobial properties to the desired article. It is at least acceptable if the molar ratio of sulfur to silver ions is in the range of 0.25: 1 to about 0.000000001: 1. However, the main vulcanizing agent must be non-sulfuric and preferably (but not necessarily) a peroxide-based compound in order to provide the desired rubber with the desired antimicrobial activity. Peroxide vulcanizing agents have been used for rubber vulcanization for some time, but these different types of vulcanizing agents are suitable as vulcanization catalysts for rubber for various reasons. It is not widely used. First, vulcanizing agents such as peroxides are more expensive than standard sulfur-based vulcanizing agents, so the use of such peroxides as a replacement for sulfur-based compounds is rather Most have been limited to silicone base rubbers or at least non-antibacterial rubber articles. However, due to the problems with antibacterial activity when such silver compounds react with sulfur-based vulcanizing agents, alternatives to sulfur-based vulcanized articles have become vigorous due to the high log sterilization effect that lasts for long periods It enabled the use of such effective antibacterial compounds in vulcanized rubber. Thus, although non-sulfur based compounds are not readily utilized as vulcanizing agents in the non-silicone industry, the use of such vulcanizing agents is necessary to provide an effective final antimicrobial vulcanized rubber article. Met.

  Surprisingly, it has been found that the rubber composition (raw or vulcanized form) of the present invention described above can be obtained without the use of detectable amounts of sulfur-based vulcanizing agents. Most importantly, with the introduction of certain additives, the structural integrity of the rubber composition is improved to an acceptable level, and the efficacy of the antimicrobial component can be controlled simultaneously.

  Accordingly, the vulcanizing agent present in the unvulcanized raw rubber composition of the present invention should be at least a majority, preferably at least about 75% by weight of the non-sulfur based vulcanizing agent. As noted above, conventional sulfur and sulfur-based catalysts do not act in the antimicrobial composition of the present invention due to chemical reactions between sulfur atoms and biocidal silver ions. However, it is not intended to be limited to non-sulfur based catalysts such as peroxides, but certain compounds such as dicumyl peroxide, 2,5-bis (t-butylperoxy) -2,5-dimethylhexane, di- organic peroxides including-(t-butyl-peroxy-isopropyl) benzene, di- (t-butyl-peroxy-trimethyl) -cyclohexane, and inorganic oxides and / or peroxides including zinc oxide, zinc peroxide, etc. The oxide effectively vulcanizes the raw rubber composition of the present invention. Such vulcanizing agents may be from about 0.5 to about 100 parts (pphr) per 100 parts rubber, more preferably from about 1 to about 50 pphr, most preferably, with only one vulcanizing agent or a combination of different types. Should be present in an amount of about 2 to about 10 pphr.

  Other additives to the rubber composition include the above silver ion release control additive, vulcanization accelerator, vulcanization accelerator activator, decomposition inhibitor, softener, abrasive, colorant, flame retardant, homogenizer Contains internal lubricants and fragrances. Such compounds, if present, should be present in rather small amounts of about 0.1 to about 100 pphr.

  Unexpectedly, it has been observed that a substantial increase in antibacterial and antifungal efficacy is provided by cleaning the final article. The surface wear of such articles also allows for increased antimicrobial properties. However, industrial cleaning of certain rubber products (such as mats) can improve efficacy such as antibacterial properties by simple cleaning. In fact, this increase has been steadily improved by multiple washings, for example, freshly vulcanized rubber articles can be washed 1, 2, 3 and at least 20 times (in a standard industrial rotary washing machine) It has been found that it exhibits lower overall antibacterial and antifungal activity than cured vulcanized rubber articles. Thus, such a surprising benefit is that such rubber articles can be used in floor coverings (for example mats such as mats with carpet or rubber alone mats; in particular during such industrial rotary washing and drying. This makes it possible to use as an anti-fatigue property and foamed rubber mat for reducing specific gravity to reduce the chance of mechanical damage) and other articles that can be easily washed in a standard industrial washing machine.

  Further, as described above, friction on the subject rubber article surface can remove a very small layer of rubber from the article surface, thereby providing a “new” that provides antibacterial and / or antifungal performance as desired. It allows silver-containing crystallites to appear on the surface. Basically, the articles of the present invention made from the raw rubber composition of the present invention exhibit a uniform dispersion of antimicrobial particles throughout the rubber article. Thus, the uniform distribution of such biocides in the rubber article provides a reservoir for new crystallites containing biocidal metal ions. As the rubber layer is worn and worn, antimicrobial particles containing unused silver ions become available.

  A preferred peroxide vulcanized rubber article of the present invention produced from the raw rubber composition of the present invention containing an antibacterial agent can be processed into a rubber article that exhibits excellent antibacterial properties of antibacterial efficacy throughout the life of the rubber article. Examples of such rubber articles included in the present invention include hard rubber mats, static dissipative rubber mats, anti-fatigue rubber mats, rubber mats containing surface fibers, rubber bonded mats, rubber gaskets, rubber medical products, rubber-containing bandages, medical devices, conveyors Includes belts, rubber gloves, rubber belts and wheels used in food processing, rubber garments, rubber shoes, rubber boots, rubber tubes and rubber automotive fuel hoses. Such compositions of the present invention can also be formulated into multilayer rubber articles where the antimicrobial agent can be incorporated into any surface layer and can provide the desired antimicrobial efficacy.

  Of particular interest is the production of multilayer rubber articles formed from the raw rubber composition of the present invention, wherein at least one of the rubber layers exhibits desirable antimicrobial activity. Such layered articles can be bonded together, such as by co-vulcanization and bonding. Further, the layer of other types of materials can be a rubber layer to provide better structural stability to the desired multilayer article as one non-limiting property.

Non-limiting preferred embodiments of these rubber compositions are described in more detail below.
A preferred embodiment of the description <br/> raw rubber composition of the present invention: (pphr = parts per 100 parts of rubber)

Samples containing different silver ion exchanged zirconium phosphate salts (available under the trade name ALPHASAN® from Milliken & Company) were made from these base compositions and are shown below. The different biocides present without corners are displayed according to the table below.

  The ingredients of each composition can be compounded by an open mill, a closed mixer or an extruder where intense mixing occurs within the polymer matrix of each ingredient. During the mixing operation, control of the temperature rise by high shear compounding of the ingredients is important to ensure that no prevulcanization (burning) occurs during the process. Generally, a maximum temperature of 120 ° C. is reached in a one-stage (pass) mixing with a closed mixer. The blend can be further processed into a specific shape after mixing to give a suitable appearance for manufacture into a product. This includes calendering, extruding, granulating / pelletizing, stripping, secondary processing and preforming into specific shaped semi-finished products.

  Vulcanization of the formulation can be done in the form of molding (compression, transfer, injection), continuous extrusion (LCM, UHF (if possible)), autoclave and hot air, and coating. The vulcanization (curing) temperature can range from 150 ° C to 250 ° C. In this particular situation, the rubber article is calendered into a rough mat structure and then vulcanized under high temperature and pressure.

Test of Vulcanized Rubber Article The following table shows the antibacterial and antifungal activities of the inventive samples and comparative samples. The antibacterial tests conducted were the AATCC draft test method for Staphylococcus aureus `` Evaluation of antibacterial properties of hydrophobic fibers and solid substrates '' and the JIS2 2801 method. ISO 486 for microbial mixture containing variotii and Trichoderma virens. Additional tests (silica, carbon black, phthalate) have been carried out for antibacterial efficacy, with further tests such as silver ion extraction with aqueous salt solution and testing of the solution by inductively coupled plasma method for silver ions extracted into the solution. Oil) was analyzed for effectiveness. Finally, industrial cleaning of such mats was performed to determine the improvement in antimicrobial activity (if any) of a sample.

  Accordingly, the composition of the present invention provided a vulcanized rubber article of the present invention exhibiting improved antimicrobial activity compared to the same composition without added antimicrobial compound.

Efficacy against fungi was assessed using ISO method 846 against Aspergillus niger ATCC 6275. The fungal mixture includes Aspergillus niger ATCC 6275, Paecilomyces variotii ATCC 18502, Trichoderma virens ATCC 9645. Place the sample on a Potato Dextrose Agar (PDA) and inoculate 10 drops (10 μl each, 100 μl total) of 10E5 fungal spores / ml in synthetic nutrient medium for 7-20 days at 30 ° C. and over 90% relative humidity Cultured. Efficacy was measured by visual observation of the sample.

Thus, the articles of the present invention not only retained antibacterial activity after washing and thus exhibited antibacterial activity, but their activity actually improved unexpectedly with increasing number of washes. This means that the amount of effective antibacterial silver ions available on the surface of the target article has increased with an increase in the number of washings. In fact, this was measured by the silver ion extraction method and found to be true for the sample. The results are shown below:

Antibacterial control and surface wear through the use of fillers and plasticizers As a very interesting and totally unexpected property, the amount of available antibacterial agent present on the surface of a rubber article after initial manufacture is in the rubber composition It was found that the presence of filler and oil increased greatly. The effect of the wear on the surface of the article is also indicated by the surface of the target article randomly contacting the abrasive block for about 5 seconds. The target article was immersed in an aqueous salt solution for extraction (sodium chloride) for 24 hours; the extract was analyzed by inductively coupled plasma measurement to determine the available silver removed from the article surface. The following table shows these measurements:

Thus, the articles of the present invention have different fillers and oils, with the largest increase caused by silica and paraffin oil additions and a uniformly greater increase in potential antimicrobial efficacy utilizing wear progression on the article surface. It showed controlled release of silver ions depending on the presence of.
Having described the invention in detail, it will be apparent to those skilled in the art that changes and modifications may be made thereto without departing from the scope of the invention. Accordingly, the scope of the invention should be determined only by the claims appended hereto.

Claims (30)

  Unvulcanized rubber composition comprising at least one rubber component selected from the group consisting of nitrile butadiene rubber (NBR), natural rubber and mixtures thereof, at least one silver-based inorganic antibacterial compound and at least one vulcanized compound Wherein all of the vulcanized compound present in the composition does not contain a detectable amount of a sulfur-based compound; the rubber composition optionally comprises at least one blowing agent, at least one silver ion An unvulcanized rubber composition comprising a controlled release additive and at least one antifungal additive other than the silver based inorganic antibacterial compound.   The rubber composition according to claim 1, wherein the silver-based inorganic antibacterial compound is selected from the group consisting of elemental silver, silver oxide, silver salt, silver ion exchange compound, silver zeolite, silver glass, and mixtures thereof.   The rubber composition according to claim 1 or 2, wherein the vulcanized compound comprises a major amount of at least one peroxide.   The rubber composition according to claim 3, wherein the peroxide is an organic peroxide.   The rubber composition of claim 1, wherein the at least one blowing agent is present.   The rubber composition of claim 1, wherein the at least one silver ion release controlling additive is present.   The rubber composition according to claim 1, wherein the antifungal additive other than the silver-based antibacterial compound is present.   The rubber composition according to claim 6, wherein the at least one silver ion release controlling additive is selected from the group consisting of fillers, oils, pigments, salts, antistatic agents and mixtures thereof.   9. The rubber composition according to claim 8, wherein the at least one silver ion release controlling additive is a hydrophilic filler selected from the group consisting of silica, stearates, and mixtures thereof.   The rubber composition according to claim 8, further comprising at least one oil selected from the group consisting of paraffin oil, phthalate oil, and mixtures thereof.   The rubber composition according to claim 1, wherein the rubber component is NBR.   The rubber composition according to claim 1, wherein the rubber component is natural rubber.   An unvulcanized rubber composition according to any one of claims 1 to 12 is blended together, the rubber composition is molded into a preselected shape, and the rubber composition is exposed to high temperature under pressure and added. A method for producing a rubber article that exhibits a reproducible antibacterial property that lasts for a long time, including a step of vulcanizing.   At least one rubber component selected from the group consisting of nitrile butadiene rubber (NBR), natural rubber and mixtures thereof, at least one peroxide vulcanizing agent and at least one silver-based inorganic antimicrobial agent, and optionally at least one A rubber composition comprising one blowing agent, at least one silver ion release inhibitor additive and at least one antifungal additive other than the silver-based inorganic antibacterial compound.   A dimensionally stable vulcanized rubber article comprising at least one rubber component selected from the group consisting of nitrile butadiene rubber (NBR), natural rubber and mixtures thereof, and at least one silver-based inorganic antibacterial agent, the rubber article comprising According to the AATCC draft method entitled `` Evaluation of antibacterial properties of hydrophobic fibers and solid substrates '' for Staphylococcus aureus and Klebsiella pneumoniae, each exhibiting a log sterilization rate of at least 1.0 after 24 hours exposure at room temperature, A dimensionally stable vulcanized rubber article optionally comprising at least one silver ion release controlling additive and at least one antifungal additive other than the silver based inorganic antimicrobial compound.   16. The rubber article of claim 15, wherein the article exhibits a log sterilization rate of at least 2.0 for Staphylococcus aureus and Klebsiella pneumoniae after 24 hours exposure at room temperature.   The rubber article according to claim 15 or 16, wherein the silver-based antibacterial compound is selected from the group consisting of elemental silver, silver oxide, silver salt, silver ion exchange compound, silver zeolite, silver glass, and mixtures thereof.   The rubber article of claim 15, wherein the at least one silver ion release controlling additive is present.   16. The rubber article of claim 15, wherein the antifungal additive other than the silver based antimicrobial compound is present.   19. A rubber article according to claim 18, wherein the at least one silver ion release controlling additive is selected from the group consisting of fillers, oils, pigments, salts, antistatic agents and mixtures thereof.   21. A rubber article according to claim 20, wherein the at least one silver ion release controlling additive is a hydrophilic filler selected from the group consisting of silica, stearate and mixtures thereof. 21. The rubber article of claim 20 , further comprising at least one hydrophilic oil selected from the group consisting of paraffin oil, phthalate oil, and mixtures thereof.   A dimensionally stable vulcanized rubber-containing article comprising at least one rubber component selected from the group consisting of nitrile butadiene rubber (NBR), natural rubber and mixtures thereof, and at least one silver-based inorganic antibacterial agent, According to the test method ISO 486 for Aspergillus niger ATCC 6275, exhibiting antibacterial properties exhibiting at least 70% inhibition in a test at 30 ° C., over 90% humidity and at least 15 days, wherein the article is optionally at least one A dimensionally stable vulcanized rubber-containing article comprising a silver ion release controlling additive and at least one antifungal additive other than the silver-based inorganic antibacterial compound. The rubber article according to claim 23 , wherein the silver-based antibacterial compound is selected from the group consisting of elemental silver, silver oxide, silver salt, silver ion exchange compound, silver zeolite, silver glass, and mixtures thereof. 24. The rubber article of claim 23 , wherein the at least one silver ion release controlling additive is present. 24. The rubber article of claim 23 , wherein the antifungal additive other than the silver based antimicrobial compound is present. 26. The rubber article of claim 25 , wherein the at least one silver ion release controlling additive is selected from the group consisting of fillers, oils, pigments, salts, antistatic agents, and mixtures thereof. 28. The rubber article of claim 27 , wherein the at least one silver ion release controlling additive is a hydrophilic filler selected from the group consisting of silica, stearates and mixtures thereof. 28. The rubber article of claim 27 , further comprising at least one hydrophilic oil selected from the group consisting of paraffin oil, phthalate oil, and mixtures thereof. The rubber article according to any one of claims 17 to 29 , wherein the article has a mat structure.