WO2001046900A9

WO2001046900A9 - Touch screen with antimicrobial properties

Info

Publication number: WO2001046900A9
Application number: PCT/US2000/035018
Authority: WO
Inventors: Jeffrey Trogolo; Roger Friedman; John Barry
Original assignee: Agion Technologies Llc; Jeffrey Trogolo; Roger Friedman; John Barry
Priority date: 1999-12-22
Filing date: 2000-12-21
Publication date: 2002-07-18
Also published as: WO2001046900A1; AU2734901A

Abstract

A touch screen for computer input having an outer surface that is to be touched by a user containing an inorganic antimicrobial agent. The agent, which can be a zeolite, is present at the surface in an effective amount to kill or retard growth of bacteria. The agent can be incorporated in a plastic resin forming the layer of the touch screen that includes the outer surface, contained in a coating applied to the outer layer of the touch screen, or contained in a laminate that is applied to the touch screen outer layer.

Description

TOUCH SCREEN WITH ANTIMICROBIAL PROPERTIES

Field of the Invention

The present invention relates to touch-type screens used with computers having antimicrobial properties.

Background of the Invention

Touch-type screens or touch screens are used in computer applications for input of data, such as in automatic teller machines, cash registers, inventory control devices, kiosks to provide information, restaurants for food order entry, gaming systems, industrial control applications, telephone number entry, and for general purpose computer data input. Such screens for inputting data are available in add-on form to be associated with an exiting video display device or are integrated as part of a display device. The screens are associated with a display of data to be entered into computers. The data can appear on the display device with which the touch screen is associated or as a printed graphic display that is part of the touch screen.

The touch screens, whether of the add-on or integrated type, utilize a variety of technologies. They all include an outer layer whose outer surface is to be touched at a location to input the desired data and various other components, such as additional underlying layers and electronic components. In resistive touch screens, finger pressure on specific areas of a deformable outer transparent screen layer completes a circuit to send a message to the computer for processing. Another type of screen uses strain gauges that react to pressure on a relatively rigid screen outer layer to measure the point at which pressure is applied to the outer layer. In a micro-wire type touch screen, each area on the screen is micro-wired as a grid with unique circuit characteristics whereby the particular point of the screen outer layer that is touched is identifiable. Other touch screens include those of the capacitive type in which a finger touches the desired area on a rigid outer layer of electrical insulating material, such as glass or a plastic resm, for data input. The capacitive properties of the finger draws current to the point touched, which is then registered by the system.

In another type of touch screen, surface acoustic wave sensors (SAWs) transmit waves across a rigid screen, such as a screen having a glass outer layer. When the outer layer is touched, a disturbance is created in the wave pattern which allows the system to determine the area being touched.

IR (infra red) touch screens operate with beams of IR energy in a grid form projected across a screen outer layer. The beams are broken by the finger placement to determine a signal position.

Piezoelectric and optical type touch screens also are used.

In common to all of the above types of touch screens, and other types, is the fact that the exposed surface of the screen outer layer is touched by the fingers of a human. Since a number of people can touch any given screen, a problem exists of possible transfer of bacteπa. That is, one person having unsanitary hands can touch a screen and leave a residue of bacteπa. The next person touching the same part of the screen can pick up the bacteπa and transfer it to his own body parts or transfer bacteπa to others during normal body contact.

If the bacteria left on the screen is of a strain that can produce a harmful medical condition, the next and subsequent persons touching the screen possibly could be adversely affected by contact with the bacteria. Therefore, it would be desirable to maintain the screen in a sanitary condition, as free of bacteria as possible, at all times. While the screen can be wiped with a liquid antiseptic solution to kill bacteria, this can only be done peπodically. Also, a liquid antiseptic is not a long-lasting solution to the problem since the liquid will evaporate Therefore, a need exits for a touch screen whose outer layer that is to be touched is provided with antimicrobial action that is continuous and long lasting.

Brief Description of the Invention

The present invention is directed to a touch screen associated with a computer, as an add on to a display device or which is an integral part of the device, wherein the screen has antimicrobial properties. In accordance with the invention, the touch screen which is to be touched by the user's finger comprises an inorganic antimicrobial agent in sufficient amount to impart a significant antimicrobial effect to the outer surface of the touch screen. The agent is present in an amount that is effective to kill, or reduce the growth of, bacteria while still leaving the screen transparent and operative for use by touch. In a preferred embodiment, the inorganic antimicrobial agent is ceramic particles comprising antimicrobial metal ions (e.g., zeolites), preferably of ceramic particles in an amount and of a type that does not adversely affect the screen transparency or electrical properties.

The agent can be incorporated in the resm forming the screen outer layer, or provided as a laminate or coating applied on the outermost screen layer. The agent is available over the entire surface area of the screen outer layer that is to be touched by the finger. The inorganic agent remains active over a long period of time.

Objects of the Invention

It is therefore an object of the invention to provide a touch screen that has antimicrobial properties for an input device associated with a computer. A further object is to provide a touch type screen whose outer layer outer surface contains an inorganic antimicrobial agent.

Yet another object is to provide a touch screen which the surface that is to be touched by a user's finger incorporates a zeolite to provide antimicrobial properties

An additional object is to provide a touch screen in which an inorganic antimicrobial agent is incorporated in the mateπal forming the screen outermost layer, is applied as a laminate to such outer layer or is coated onto the layer.

Brief Description of the Drawings

Other objects and advantages of the present invention will become more apparent upon reference to the following specification and annexed drawings in which:

Fig. 1 is a diagrammatic view of a type of touch screen having an outer layer that is rigid;

Fig. 2 is a diagrammatic cross-sectional view of a touch screen whose outer layer is of a deformable mateπal;

Fig. 3 is a diagrammatic view of a touch screen in which a coating is applied to the outer layer, and

Fig. 4 is a diagrammatic cross-sectional view of a touch screen in which a laminate containing the antimicrobial agent is applied to the screen outer layer. Detailed Description of the Invention

For all of the embodiments of the invention, a preferred antimicrobial agent is an agent comprising ceramic particles containing antimicrobial metal ions, such as a zeolite subject to ion exchange with antimicrobial metal ions, such as silver ions. Suitable zeolites are generally disclosed in U.S. Patents 4,938,955 and 4,906,464.

In the preferred embodiment of the invention, the inorganic antimicrobial agent is ceramic silver zeolite particles, such as AJ10D, made by Shinagawa Company of Osaka, Japan, and which are of a nominal 1.0 micron size.

The antimicrobial agent is present in an effective amount to impart antimicrobial properties to the screen surface to be touched by the user.

The amount of the antimicrobial agent will vary based on the specific inorganic agent used, its composition, the mateπal with which it is mixed or added to, and upon known factors such as type and use of the product containing the agent. Environmental factors, such as the temperature of the environment where the touch screen is located and of any associated electronic components, also should be taken into consideration. It is within the ability of one skilled in the art to in view of this disclosure to relatively easily determine an effective amount of the antimicrobial agent to be used with each material.

Since the particle size of the agent is small, preferably 1.0 micron or less, incorporation into the screen outer layer mateπal will not adversely affect the transparency needed for the touch screen if the amount of antimicrobial agent is not excessive Fig. 1 is a diagrammatic view showing the general principles of one type of touch screen 10. This is used for illustrative purposes. The invention is applicable to all of the foregoing types of touch screens discussed, and others. Here, the screen 10 has a rigid outer layer 12 of a plastic material, for example a polycarbonate such as sold under the name LEXAN. The touch screen outer layer 12 is of a desired thickness and is associated with a number of other components generally designated by reference numeral 16. For example, if the touch screen is of the IR type, there would be optoelectronic members, such as mounted in a bezel, around the perimeter of the outer layer 12, and various electronic components. The details of the other parts of the touch screen are conventional and are not critical to the subject invention. In the touch screen 10 of Fig. 1 the invention provides the antimicrobial agent on the entire outer surface of outer layer 12

In Fig. 2, the touch screen 20 illustratively is of the pressure sensitive type. Here, the outer layer 22 is of a transparent elastomeπc polymeric material having the agent available on the outer surface that is contacted and pressed by the user's finger. Fig. 2 is illustrative, for example, of a resistive, micro-grid or piezoelectric type of touch screen.

In Fig. 3, the outermost part of the touch screen 30 is a rigid plate 32 of transparent material such as a plastic resm or glass. Here, there is a transparent coating 34 as the outer layer that contains the inorganic antimicrobial agent. Fig. 3 is illustrative, for example, of a portion of a capacitive or strain gauge type of touch screen.

Fig. 4 shows a touch screen 40 whose outermost part also is a transparent plate 32 of glass or plastic resm. Here, a transparent laminate layer 44 containing the agent is bonded to the plate 32 as the outer layer containing the agent. Fig 4 also is illustrative of a capacitive or strain gauge type of touch screen. In accordance with the invention, the transparent outer layer of the touch screen of the types described above or of any other type that is to be touched by the user's finger is to be provided with antimicrobial properties. To accomplish this, the antimicrobial agent is to be present on the surface of the screen outer layer that is to be touched by the finger. Provision of the agent for the various screen configurations is described below.

Antimicrobial Agent is incorporated in a resm rigid outer layer. One type of outer layer of the touch screen, such as shown in Fig. 1 , is made of a resm material, such as a polycarbonate. One such well-known type of this material is sold under the name LEXAN. For a touch screen whose outer layer is of a plastic resin material, the agent is preferably incorporated into the resin from which such layer is made.

The resins into which the zeolite is incorporated can be those such as polyurethane, polyethylene, polypropylene, polystyrene, polyvmyl chloride, polycarbonates and others as disclosed in said patents. Methods of zeolite incorporation are disclosed in the foregoing U S. Patents 4,938,955 and 4,906,464.

The ceramic silver zeolite particles of the preferred embodiment can be incorporated, such as by kneading, into the resm for the screen layer and the layer formed in its normal manner, such as by molding, casting or extrusion.

The ceramic particles are mixed with the resin in the manner described in the aforesaid patents. The concentration of the particles of the agent is preferably in the range of from 0.1 to 20.0 wt%, more preferably from 0.1 to 10.0 wt%, and most preferably from 0.5 to 5 0 wt% of the total weight of the resin forming the screen outer layer. The inorganic antimicrobial agent in the form of the zeolite particles is available throughout the entirety of the screen outer layer, including the entire outer surface that is to be touched by the user, to perform its antimicrobial action. The agent kills or reduces the growth of bacteria on such surface

In general, the antibiotic particles are preferably present in an effective amount in a concentration by weight in the resin used to form the screen layer to impart antimicrobial properties to the screen layer. This means that there is a sufficient amount of the antimicrobial agent added to or combined with other materials, such as resin to form the layer, so as to be present on the exposed surface to prevent or inhibit the growth of bacteπal and/or fungal organisms or to kill such organisms. This is within the skill of the art in light of the present specification.

It is preferred that the final amount of the zeolite particles be in the range of from about 0.5 to 2.0% of the total weight of the resm for the screen layer so that it will still be transparent. It has been found that if the agent is about 2.0 wt% or less of the screen material and the ceramic zeolite particles are of 1.0 micron or smaller in size, that requirement for transparency can be met. Also, even though in the preferred embodiment the agent comprises ceramic particles having a metal component, the electrical properties of the touch screen will not be seriously adversely affected, whether the screen is of the resistive, capacitive or of another type.

A preferred embodiment according to the invention of a screen made from a resin that contains the zeolite particles has: resin of screen polycarbonate antimicrobial agent AJ10D (Shimgawa) agent particles/size 1.0 micron

Final wt% of agent in resin 2.0% used for the screen When the desired resin for the touch screen outer layer is in liquid form, the zeolite ceramic particles are mixed with the liquid resin. The mixing is thorough to uniformly disperse the zeolite particles. A liquid mixture of the zeolite particles and the resin is obtained. The mixing should be thorough to uniformly disperse the zeolite particles. Here also, in a preferred embodiment, the zeolite particles are preferably present in the range of 0.5 to 2.0 wt% of the liquid resm and are of 1.0 micron size or smaller. The liquid resm containing the particles is processed in a conventional manner, such as by casting, molding or extension, to form the screen rigid outer layer.

Agent is incorporated in deformable outer layer. The touch screen 20 outer layer 22 of Fιg.2 also is of a plastic resin material but this is deformable. That is, the plastic resin has elastomeπc properties and is relatively transparent. A suitable material is clear sihcone rubber. Other suitable elastomeπc materials can be used.

In this embodiment the agent particles are mixed into the elastomeπc material in the desired amount and the mixture is extruded in sheet form of the desired thickness in the conventional manner. The sheet containing the inorganic agent particles is cut to the desired size and incorporated into the touch screen as the normal screen outer layer 22. The agent particles are present throughout the entire surface of the outer layer 22 that is to be touched and depressed.

Thus, the desired antimicrobial action is achieved.

In a preferred embodiment of a deformable outer layer for the touch screen: resin of screen clear sihcone rubber antimicrobial agent AJ10D (Shimgawa) silver zeolite agent particles/size 1.0 micron Final wt% of agent m resm 5.0% used for the screen The thickness of the layer 22 can be substantially the same as for deformable layers of the same material that do not contain the agent

Coating the outer layer exposed surface. In this embodiment, such as illustrated in Fig. 3, the touch screen outermost part is a plate 32 of glass or other rigid material that is formed in the normal manner of the desired material and process. After its formation, a coating containing the agent is applied to the outer surface of the touch screen outer plate 32. Polymer coatings of transparent material are preferred for this embodiment. The coating preferably can be of, for example, a hydrophihc polymer such as hydrophihc polyurethane, or an acrylic, both of which are transparent

To make the coating material, particles containing the antimicrobial agent are mixed with the resm in the desired amount. Here also, the amount of the agent particles is such that the transparency of the coating will not be adversely affected and its application will not adversely affect the screen electπcal properties. Here the percentage of the ceramic zeolite particles, when used, by total weight of the coating is from about 1.0 to 90.0 wt%, more preferably from about 1.0 to 65.0 wt% and most preferably from about 5.0 to 45.0 wt%, and the size of the agent particles also preferably is less than 5.0 microns.

The coating with the agent is applied to the screen outer layer outer surface by any suitable technique, such as dipping, spraying or painting. The agent is available in the coating on the outer surface to be touched by the finger to perform its antimicrobial action.

A typical embodiment of the coating is: coating material acrylic agent AJ10D (Shimgawa) silver zeolite agent particle size 1.0 micron wt% of agent particles 15.0 in coating thickness of coating 3 mils

Outer layer is a laminate containing the agent

Here, as illustrated in Fig. 4, the outermost part of the touch screen 40 is a plate 32 of rigid material, such as glass or a suitable resm. Here, a laminate layer 44 forms the outer layer of the touch screen. The laminate layer is a sheet of transparent material formed in the same manner previously descπbed of either a plate of resin containing the agent, such as would be used for the outer layer 12 of Fig. 1, or of deformable elastomeπc material containing the agent, such as for the outer deformable layer 22 of Fig. 2.

The sheet for layer 44 is made to the appropriate size and thickness. It is bonded to the outer surface of the plate 32 by any suitable process compatible with the mateπal of the layer, such as an adhesive, ultrasonic welding, heat bonding, as a laminated outer layer. Since the agent particles are present throughout the entirety of the laminate layer 44, they will be present on the layer outer surface that is touched to perform the desired antimicrobial action.

A typical embodiment for the laminate layer 44: laminate material sihcone rubber agent AJ10D (Shimgawa) silver zeolite agent particle size 1.0 micron wt% of agent particles 2.0 in laminate thickness of laminate 25.0 microns Inorganic Agent.

Preferred inorganic antimicrobial agents incorporated in the resin or used in the coating use metal ions (cations), such as mercury, tin, lead, bismuth, cadmium, chromium and thallium ions, as the active agent These antibiotic or antimicrobial metal ions are believed to exert their effects by disrupting respiration and electron transport systems upon absorption into bacterial or fungal cells Antimicrobial metal ions (cations) of silver, gold, copper and zinc, in particular, are considered safe even for in vivo use. Antimicrobial silver ions are particularly useful for in vivo use due to the fact that they are not substantially absorbed into the body. That is, if such materials are used they should pose no hazard

In one embodiment of the invention, the inorganic antimicrobial metal containing composition is an antibiotic metal salt Such salts include silver acetate, silver benzoate, silver carbonate, silver lonate, silver iodide, silver lactate, silver laureate, silver nitrate, silver oxide, silver palpitate, silver protein, and silver sulfadiazme. Silver nitrate is preferred These salts are particularly quick acting, as no release from ceramic particles is necessary to function antimicrobially

Ceramic particles, including particles comprising silver, copper or zinc ions, have been shown to possess antimicrobial or antibiotic activity. These particles involve slow release of the antibiotic metal, such as silver, from the zeolite particles. This is suitable for the resin forming the screen outer layer or for the coating and laminate materials

Antimicrobial ceramic particles useful with the present invention include zeolites, hydroxy apatite, zirconium phosphates or other ion-exchange ceramics. Zeolites are preferred Hydroxy apatite particles containing antimicrobial metals are described, e.g , in U.S. Patent No. 5,009,898. Zirconium phosphates containing antimicrobial metals are descπbed, e.g., in U.S. Patent Nos. 5,296,238, 5,441,717; and 5,405,644. Other suitable antimicrobial agents include inorganic particles, such as the oxides of titanium, aluminum, zinc and copper, which may be coated with a composition which confers antimicrobial properties, for example, by releasing antimicrobial metal ions such as silver ions, which are described, e.g., in U.S. Patent No. 5,890,585. Inorganic soluble glass particles containing antimicrobial metal ions, such as silver, are described, e.g., in U.S. Patent Nos. 5,766,611 and 5,290,544.

Antibiotic or antimicrobial zeolites are preferred. These have been prepared by replacing all or part of the ion-exchangeable ions in zeolite with ammonium ions and antimicrobial metal ions, as described in U.S Patent Nos. 4,938,958 and 4,911,898. Such zeolites have been incorporated in antimicrobial resins (as shown in U.S. Patent Nos 4,938,955 and 4,906,464) and polymer articles (U.S. Patent No. 4,775,585). Polymers including the antimicrobial zeolites have been used to make refrigerators, dish washers, rice cookers, plastic film, vacuum bottles, plastic pails, and garbage containers. Other materials in which antimicrobial zeolites have been incorporated include flooring, wall paper, cloth, paint, napkins, plastic automobile parts, bicycles, pens, toys, sand, and concrete. Examples of such uses are descπbed in U.S. Patents 5,714,445; 5,697,203; 5,562,872; 5,180,585, 5,714,430; and 5,102,401.

Either natural zeolites or synthetic zeolites can be used to make the antibiotic zeolites used in the present invention. "Zeolite" is an aluminosilicate having a three dimensional skeletal structure that is represented by the formula: XM₂ „0«Al₂θ3»YSιθ₂»ZH₂0. M represents an ion-exchangeable ion, generally a monovalent or divalent metal ion, n represents the atomic valency of the (metal) ion, X and Y represent coefficients of metal oxide and silica respectively, and Z represents the number of waters of crystallization. Examples of such zeolites include A-type zeolites, X-type zeolites, Y-type zeolites, T-type zeolites, high-silica zeolites, sodalite, mordenite, analcite, clinoptilohte, chabazite and eπonite. The present invention is not restricted to use of these specific zeolites.

The ion-exchange capacities of these zeolites are as follows: A-type zeolite = 7 meq/g; X-type zeolite = 6 4 meq/g; Y-type zeolite = 5 meq/g; T-type zeolite = 3.4 meq/g; sodalite = 11.5 meq/g; mordenite = 2.6 meq/g; analcite = 5 meq/g; clinoptilohte = 2 6 meq/g; chabazite = 5 meq/g; and eπonite = 3 8 meq/g. These ion-exchange capacities are sufficient for the zeolites to undergo ion-exchange with ammonium and antimicrobial metal ions.

The specific surface area of preferred zeolite particles is preferably at least 150 m²/g (anhydrous zeolite as standard) and the S1O₂/AI₂O₃ mol ratio in the zeolite composition is preferably less than 14, more preferably less than 11.

The antimicrobial or antibiotic metal ions (cations) used in the antibiotic zeolites should be retained on the zeolite particles through an ion-exchange reaction. Antibiotic metal ions which are adsorbed or attached without an ion-exchange reaction exhibit a decreased bactericidal effect and their antibiotic effect is not long-lasting. Nevertheless, it is advantageous for imparting quick antimicrobial action to maintain a sufficient amount of surface adsorbed metal ion.

In the ion-exchange process, the antimicrobial metal ions (cations) tend to be converted into their oxides, hydroxides, basic salts etc. either in the microforms or on the surfaces of the zeolite and also tend to deposit there, particularly when the concentration of metal ions in the vicinity of the zeolite surface is high. Such deposition tends to adversely affect the bactericidal properties of ion-exchanged zeolite. In an embodiment of the antimicrobial zeolite, a relatively low degree of ion exchange is employed to obtain superior bactericidal properties. It is believed to be required that at least a portion of the zeolite particles retain metal ions (cations) having bactericidal properties at ion-exchangeable sites of the zeolite in an amount less than the ion-exchange saturation capacity of the zeolite. In one embodiment, the zeolite employed in the present invention retains antimicrobial metal ions in an amount up to 41% of the theoretical ion-exchange capacity of the zeolite. Such ion-exchanged zeolite with a relatively low degree of ion-exchange may be prepared by performing ion-exchange using a metal ion solution having a low concentration as compared with solutions conventionally used for ion exchange.

The zeolite preferably comprises an integral discoloration agent such as ion-exchanged ammonium. Although ammonium ions may be contained in the zeolite at a concentration as high as about 20% by weight of the zeolite, it is desirable to limit the content of ammonium ions to about 0 5 to about 2.5%, more preferably from about 0.5 to about 2 0%, and most preferably, from about 0.5 to about 1.5% by weight of the zeolite.

In the antimicrobial zeolite particles used in the present invention, ion-exchangeable ions (cations) present in zeolite, such as sodium ions, calcium ions, potassium ions and iron ions are partially replaced with antimicrobial metal ions, such as silver The antimicrobial zeolite typically comprises from about 0.5 to about 15% and preferably from about 0.5 to about 2% by weight of ion-exchanged silver based upon 100% total weight of zeolite. Other antimicrobial metal ions may be included in the zeolite such as copper, zinc, mercury, tin, lead, bismuth, cadmium, chromium, thallium, or a combination thereof. Such ions may co-exist in the antimicrobial zeolite particles since they do not prevent the bacterial effect of the zeolite particles. These antimicrobial metal ions may be incorporated into the zeolite by themselves or in a mixture. In one embodiment, the zeolite contains from about 0.1 to about 15% by weight of silver ions and from about 0.1 to about 8% by weight of copper or zinc ions.

The antimicrobial or antibiotic metal ion is preferably present in the range of from about 0.1 to 20wt.% of the zeolite. In one embodiment, the zeolite contain from 0.1 to 20wt.% of silver ions and from 0.1 to 20wt.% of copper or zinc ions. Although ammonium ions can be contained in the zeolite at a concentration of about 20 wt.% or less of the zeolite, it is desirable to limit the content of ammonium ions to from 0.5 to 15 wt.%, preferably 1.5 to 5 wt.%. Weιght% descπbed herein is determined for materials dried at temperatures such as 110°C, 250°C or 550°C as this is the temperature employed for the preferred post-manufacturing drying process.

A preferred antimicrobial zeolite is type A zeolite containing either a combination of ion- exchanged silver, zinc, and ammonium or silver and ammonium. One such zeolite is manufactured by Shmagawa, Inc under the product number AW-10N and consists of 0.6% by weight of silver ion-exchanged in Type A zeolite particles having a diameter of about 2.5μ. Another formulation, AJ-10N, consists of about 2%> by weight silver ion-exchanged in Type A zeolite particles having a diameter of about 2.5μ Another formulation, AW-80, contains 0.6% by weight of silver ion- exchanged in Type A zeolite particles having a diameter of about 1.0μ. Another formulation, AJ- 80N, consists of about 2% by weight silver ion-exchanged in Type A zeolite particles having a diameter of about l.Oμ. These zeolites preferably contain about between 0.5% and 2.5% by weight of ion-exchanged ammonium. A further product is AJIOD, which consists of about 2% by weight of silver ion exchanged in Type A zeolite particles having a diameter of about l.Oμ.

The zeolite are often obtained in master batches of low density polyethylene, polypropylene, or polystyrene, containing 20 wt% of the zeolite. Thus, they can be easily mixed with the resms used as mateπals for forming the foam. The antimicrobial properties of the antimicrobial zeolite particles of the invention may be assayed while in aqueous formulations using conventional assay techniques, including for example determining the minimum growth inhibitory concentration (MIC) with respect to a variety of bacteπa, Eumycetes and yeast In such a test, the bacteria listed below may be employed

Bacillus cereus varmycoides,

Eschertchia coh,

Pseudomonas aeruginosa,

Staphylococcus aureus, Streptococcus faecahs ,

Aspergillus mger,

Aureobasidutm pullulans,

Chaetomium globosum,

Glwcladium virens, Penicillum funiculosum,

Candida albwans, and

Saccharomyces cerevisiae

The assay for determining MIC can be carried out by smearing a solution containing bacteria for inoculation onto a plate culture medium to which a test sample of the encapsulated antibiotic zeolite particles is added in a particular concentration, followed by incubation and cultuπng of the plate The MIC is defined as a minimum concentration thereof required for inhibiting the growth of each bacteπa

Safety and biocompatibihty tests were conducted on the antibiotic zeolite employed in the invention ISO 10993-1 procedures were employed The following results were obtained Cytotoxicity: Non-Toxic

Acute Systemic Toxicity: Non-Toxic

Oral Toxicity: Safer than table salt

Intracutaneous Toxicity: Passed

Skin Irritation Test: Non-Irritant

Chronic Toxicity: No Observable Effect

In-vitro Hemolysis: Non-Hemolytic

30-day Muscle Implant Test: Passed

60-day Muscle Implant Test: Passed

90-day Muscle Implant Test: Passed

Ames Mutagenicity Test: Passed

Pyrogenicity: Non-Pyrogenic

Thus, the antibiotic zeolite are exceptionally suitable under relevant toxicity and biocompatibihty standards for use in the outer screen layer, coatings and laminates.

Specific features of the invention are shown in one or more of the drawings for convenience only, as each feature may be combined with other features in accordance with the invention. Alternative embodiments will be recognized by those skilled in the art and are intended to be included within the scope of the claims. Accordingly, the above description should be construed as illustrating and not limiting the scope of the invention.

Claims

WE CLAIM:

1. A touch screen for computer input, said screen having an outer surface to be contacted by touching, said screen comprising an inorganic antimicrobial agent in sufficient amount to impart a significant antimicrobial effect to said outer surface.

2. The touch screen of claim 1, wherein said inorganic antimicrobial agent comprises ceramic particles comprising antimicrobial metal cations.

3. The touch screen of claim 2 wherein said ceramic particles are zeolites subject to ion exchange with silver cations.

4. The touch screen of claim 1, wherein said touch screen is transparent.

5. A touch screen for computer input, said screen having an outer surface to be contacted by touching, wherein said screen comprises a plastic resin comprising an inorganic antimicrobial agent in sufficient amount to impart a significant antimicrobial effect to said outer surface.

6. The touch screen of claim 5, wherein said plastic resm is an elastomer.

7. The touch screen of claim 5, wherein said inorganic antimicrobial agent comprises ceramic particles comprising antimicrobial metal cations.

8. The touch screen of claim 7, wherein said ceramic particles are zeolites subject to ion exchange with silver cations.

9. The touch screen of claim 8, wherein said zeolite particles are present in an amount of from 0.1 to 20.0 wt% of the total weight of said plastic resm mateπal.

10. The touch screen of claim 9, wherein said zeolite particles are present m an amount of about 2.0 wt% and a particle size of about 1.0 micron.

11. The touch screen of claim 5, wherein said touch screen is transparent.

12. A touch screen for computer input, said screen having an outer surface to be contacted by touching, wherein said outer surface of said touch screen comprises a polymeric coating, and said inorganic antimicrobial agent is present in said polymeric coating in sufficient amount to impart a significant antimicrobial effect to said outer surface.

13. The touch screen of claim 12, wherein said polymeric coating comprises a polymer selected from the group consisting of polyurethane or an acrylic polymer.

14. The touch screen of claim 12, wherein said inorganic antimicrobial agent comprises ceramic particles comprising antimicrobial metal cations.

15. The touch screen of claim 14, wherein said ceramic particles are zeolites subject to ion exchange with silver cations.

16. The touch screen of claim 15, wherein said zeolite particles are present in an amount by total weight of said polymeric coating of from about 5.0 to 45.0 wt%, and said zeolite particles have a particle size of less than 5.0 microns.

17. The touch screen of claim 12, wherein said polymeric coating is a laminate layer comprising said inorganic antimicrobial agent.

18. The touch screen of claim 17, wherein said inorganic antimicrobial agent comprises ceramic particles comprising antimicrobial metal cations.

19. The touch screen of claim 18, wherein said ceramic particles are zeolites subject to ion exchange with silver cations

20. The touch screen of claim 12, wherein said touch screen is transparent.