WO2008040965A2

WO2008040965A2 - Doors

Info

Publication number: WO2008040965A2
Application number: PCT/GB2007/003743
Authority: WO
Inventors: Philip Reed
Original assignee: Philip Reed
Priority date: 2006-10-04
Filing date: 2007-10-03
Publication date: 2008-04-10
Also published as: WO2008040965A3

Abstract

A fingerplate (4) and/or a door handle cover (3) incorporates an anti-microbial substance in the form of glass particles which release silver ions (Ag+). The anti-microbial substance is incorporated into the thermoplastic moulding material. The cover may be of tubular form with a longitudinal slit to assist application to the door handle.

Description

DOORS

TECHNICAL FIELD OF THE INVENTION

This invention relates to doors, and to the problem of reducing the everyday risk of cross-infection by micro-organisms.

BACKGROUND

Controlling the spread of diseases caused by bacteria and fungal infections is a major problem in hospitals, and indeed, in other areas to which people have access. The emergence of bacteria which are resistant to most known antibiotics is a serious problem worldwide. Many bacterial diseases such as MRSA, Clostridium difficile and certain strains of e. coli can prove to be fatal, and are easily acquired by direct skin contact with surfaces contaminated with these micro-organisms. C. difficile causes a range of diseases from antibiotic-associated diarrhoea to a life-threatening colon disease called pseudomembranous colitis, and presents a particular problem for healthcare professionals because it can only be treated with two antibiotics, metronidazole and vancomycin, and there is concern that these too will soon become ineffective. Such diseases are easily acquired by direct skin contact with surfaces contaminated with the bacteria, and a wide variety of fungal diseases can also be propagated in a similar mariner. Common hygiene advice aimed at reducing the spread of such diseases is to practice frequent hand washing, preferably using disinfectant solutions, but although this remains good practice it can never be completely effective no matter how diligently it is carried out. For example, if someone goes to the toilet in a restaurant and washes their hands as advised they can easily pick up new infections as they leave the toilet area.

A significant number of people suffer allergic reactions to common disinfectant solutions, and many more people are liable to encounter adverse reactions with prolonged and repeated skin contact with these agents. Thus, measures which involve securing contact elements to a door as proposed in GB 2 402 622 A, which comprise a porous fibrous material saturated with a disinfecting agent, are themselves likely to give rise to health and safety issues. In addition, most common disinfectants have a very limited lifespan, measured in hours or days, so that they require constant maintenance to maintain their effectiveness.

The addition of various bioactive agents to moulded thermoplastic articles in order to combat the growth of micro-organisms on the thermoplastic surfaces is known. For example, US 2004/0137075 A1 discloses the use of a bioactive glass as an additive for polymers, which does not contain any heavy metals. Non-specific biocidal polymers are also used in various injection moulded plastic items, well known examples being 2,4,4'- trichloro-2'-hydroxydiphenol ether, or 5-chloro-2-phenol (2,4 dichlorophenoxy) as sold under the trademark Microban, by Microban Products Company, Huntersville, N. C. However, many such agents require regular surface activation (e.g washing with water) to maintain their effectiveness, and show a marked reduction in antibacterial activity with time.

It is widely known that silver, in the form of metallic silver or silver salts, is toxic to micro-organisms. US 4 849 223 discloses an antimicrobial coating composition for use in medical applications which includes silver as the antimicrobial agent. GB 2 427 139 A discloses an antimicrobial paint which contains 0.2% by weight of a silver-containing additive.

The present invention seeks to provide a new and inventive way of reducing the spread of infections through hand transmission and which is highly effective against antibiotic-resistant bacteria for a substantial period without requiring further attention.

SUMMARY OF THE INVENTION

The present invention proposes a door having an area of its external surface provided with a cover moulded of a thermoplastic polymer incorporating a hydrolysable matrix which releases silver ions (Ag+).

Heavy metal ions such as silver interfere with, and may block, the cellular transport mechanisms of bacteria and other micro-organisms, resulting in their rapid destruction. The ions may also cause similar effects in many yeasts and fungi, although their effect on the tissue cells of higher organisms such as humans is benign.

The hydrolysable matrix may be added to the thermoplastic polymer in a particulate form. A particularly effective form of hydrolysable matrix comprises particles of glass. Such a matrix is extremely stable to temperatures beyond 500⁰C, and can withstand extreme acid or alkaline conditions without significantly reducing the release of the silver ions. The use of a hydrolysable glass matrix also enables a high concentration of silver ions in a highly active form to be maintained at the surface of the thermoplastic polymer

For optimum effect against known pathogenic bacteria the silver- containing matrix is preferably added to the thermosetting plastic in a proportion of between 2% and 10% by weight, the preferred proportion being about 6% by weight.

In one embodiment the cover may take the form of a fingerplate.

In another embodiment the cover may be shaped to fit over a door handle, and may, for example, be of tubular form with a slit extending along at least part of its length.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice. In the drawings:

Figure 1 is a general view of a door in accordance with the invention;

Figure 2 is a front view of a first embodiment of a door cover in the form of finger plate for attachment to the door;

Figure 3 is a side view of a second embodiment of a door cover in the form of a handle cover for the door; and

Figure 4 is a side view of another form of the handle cover.

DETAILED DESCRIPTION OF THE DRAWINGS

Fig. 1 shows one side of a door 1 which is hung in a doorway through which people can pass. By way of example, the invention may be applied to a toilet door, although it will be appreciated that the invention may advantageously be applied to any door, whether in a public building, in commercial premises, in the home, on board a ship, etc. It should also be noted that although only one side of the door is shown and described the invention may advantageously be applied to both sides of the door.

The door 1 is hung on hinges 2 and may be opened and closed in known manner using a lever-type handle 3. It has been found that when using a door hand contact is most frequently made with two specific areas. Firstly, hand contact is made directly with the door handle 3 during opening and closing of the door. The second common area of hand contact is made in an area immediately above the door handle. Indeed, this can cause wear and discolouration of the door and for this reason it is known to protect the area by attaching a plate 4 to the door, commonly known as a fingerplate.

The fingerplate, which is shown in Fig. 2, is a flat elongate panel 10 which is moulded of a thermoplastic such as polyurethane, high impact polystyrene (HIPS) or polyvinyl chloride (PVC). The fingerplate may be attached to the door by means of a self-adhesive layer applied to the rear face of the panel, protected by a peelable backing prior to use. By introducing known colourants into the thermoplastic the fingerplate may be moulded in a range of colours. The thermoplastic incorporates an antibacterial additive which is effective against pathogenic bacteria such e. coli and MRSA. When anyone touches the fingerplate 10 any bacteria or fungi transferred to the door will quickly be rendered inactive, reducing or even eliminating the risk of transmission to other users.

Fig. 3 shows an anti-microbial cover 12 which is applied to the door handle 3. The cover is of tubular form and is provided with a single slit 13 extending helically from end-to-end. The cover is moulded of a flexible resilient thermoplastic such as polyvinyl chloride (PVC), so that the cover tends to return to the helical configuration in which it was manufactured. The thermoplastic moulding material again includes an antibacterial additive as described below, and may incorporate known colourants or other additives. The cover may easily be applied to the lever portion of the door handle by twisting the cover in a direction which tends to unwind it. When in place, the cover firmly grips the handle due to its resilient nature. When anyone grips the cover during use of the handle any bacteria or fungi transferred to the handle are destroyed.

The cover may be moulded in any convenient shape to fit over and grip the handle, depending on the shape of the handle. For example, the cover 14 shown in Fig. 4 is tubular with a straight end-to-end slit 15. The cover could again be formed of polyvinyl chloride (PVC) with an antimicrobial additive. This form of cover is less flexible than the cover shown in Fig. 3 but is easier to apply to a handle of the kind which is fixed to the door at both ends, for example, simply by opening up the slit 15 to insert the handle.

In each of the above embodiments the fingerplate or handle cover incorporates an additive which releases silver (Ag+) ions. A suitable additive for HIPS is Bactiglas AM 92667, and a suitable additive for PVC is Bactiglas AM 93456. The silver ions are held in particles of a hydrolysable glass matrix which is extremely stable to temperatures beyond 500⁰C and protects the ions during thermal processing of the plastic. The glass particles are thoroughly mixed into the thermoplastic moulding material, in a proportion of about 6% by weight, to achieve a uniform distribution. Once the plastic is set, in the presence of minute amounts of moisture silver ions are released from the surface of the plastic at a continuous but extremely slow rate. The slow release of Ag+ ions acts as a biocide which interrupts the normal membrane functions of bacteria, algae and fungi which come into contact with the door covers, resulting in rapid destruction of the micro-organisms. At the surface of the thermoplastic the released silver ions either complex in solution or loosely combine with the polymer forming active, but highly stable complexes which remain at the surface, holding the silver in an active form.

The silver-glass matrix can withstand extreme acid or alkaline conditions without significantly affecting the release or biocidal activity of the silver ions.

Tests carried out by a Japanese laboratory have shown that the surfaces of the polymer are better than 99.995% effective at destroying MRSA bacteria, e. coli and s. aureus, which is considerably more effective than other antibacterial surface treatments. Independent tests have also confirmed that the antibacterial properties are not significantly diminished after a period of eight years.

It will be appreciated that the features disclosed herein may be present in any embodiment of the invention in any feasible combination. Whilst the above description places emphasis on those areas which, in combination, are believed to be new, protection is sought for any inventive combination of the features disclosed herein.

Claims

1. A door having an area of its external surface provided with a cover moulded of a thermoplastic polymer incorporating a hydrolysable matrix which releases silver ions (Ag+).

2. A door according to Claim 1 in which the hydrolysable matrix is distributed throughout the thermoplastic polymer in a particulate form.

3. A door according to Claim 2 in which the hydrolysable matrix comprises particles of glass.

4. A door according to Claim 3 in which the particles of glass are incorporated into the thermoplastic polymer in a proportion of between 2% and 10% by weight.

5. A door according to Claim 4 in which the particles of glass are incorporated into the thermoplastic polymer in a proportion of substantially 6% by weight.

6. A door according to Claim 1 in which the cover comprises a fingerplate.

7. A door according to Claim 6 in which the fingerplate is attached to the door by means of an adhesive layer.

8. A door according to Claim 1 in which the cover is shaped to fit over a door handle.

9. A door according to Claim 8 in which the cover is moulded of a flexible resilient thermoplastic.

10. A door according to Claim 9 in which the cover is of tubular form with a slit extending along at least part of its length.

11. A door according to Claim 10 in which the slit extends from end-to-end of the cover.

12. A door according to Claim 11 in which the slit is substantially helical.

13. A door according to Claim 11 in which the slit is substantially straight.