DE4403016A1 - Microbicidal plastic articles partic. for medical use - Google Patents

Abstract

Plastic articles contain a biocide in the form of discrete particles embedded in the plastic matrix. The biocide comprises one or more bactericidal and/or fungicidal metals and/or metal cpds. and is present in an amt. of up to 0.5 wt.%. The particle size distribution of the biocide has a peak below 500 nm. Also claimed is a process for producing articles as above, comprising chemically or physically coating a plastic blank with the biocide, comminuting and/or melting the coated blank, and forming the article from the prod..

Description

The invention relates to plastics which can be processed especially for the production of objects for the medical need that have an antimicrobial Ge hold metal or metal compounds.

These include, in particular, such metals or their ver understand bonds, their oligodynamic effect be is known, such as B. silver, copper and gold, but also on their heavy metals such. B. zinc and also lanthanides, the on bacteria and / or fungi in the desired according to the invention Act meaning, d. H. kill them, their multiplication or too their adherence to or implantation in the plastic prevent or at least greatly reduce.

Such preliminary products or finished parts from such art According to the current state of the market, substances are still not generally available, but according to the state of the art quite functional.  

One reason that the market launch is not yet significant tem scope has occurred, the question of effort and hence the cost of manufacturing such plastics his.

On the one hand, this affects the cost of the target Purpose necessary amounts of the metal or the metal compound applications, especially of silver, if these substances in powdery form should be worked into the plastic len, whereby the lower effectiveness limit always Of the order of 1% by weight of the plastic will always consider larger shares to be even more effective are given. In this context, the patent publications US-A-4 054 139, WO-A-84/01721; EP-A- 0 190 504, DE-A-37 25 728, EP-A-0 251 783 and DE-A-39 42 112 referred.

On the other hand, that affects the cost of that quite complex and accordingly only expedient Wet methods of loading to be used for selected cases action of plastics z. B. according to DE-C-42 26 810, according to which very small amounts of the active substance is sufficient are.

Another way of paying for the high material costs to avoid antimicrobial treatment of objects, is not antimicrobial on the whole of the plastic equip, but the made of this plastic Subsequent coating of objects with active substances.

However, all physical processes (such as e.g. B. Evaporation, sputtering, plasma-assisted loading vaporization, ion plating, ion implantation) and also the chemical processes (e.g. electroless plating, reactive ves vapor deposition, reactive sputtering, CVD, PACVD) so, that only that of the respective source of the to be applied Active substance facing surfaces or, for. B. in the case of  Plasma-supported processes, at least only those of the Areas openly facing the surrounding area must be coated. The for medical applications usually particularly important nenflächen of objects, for. B. the inside of Kathe tern are for the application of these procedures but inaccessible and therefore remain uncoated.

The object of the present invention is therefore ready position of oligodynamically effective plastic bodies, which do not have the above disadvantages, i. H. a can only be produced with a small amount of oligodyna mix metal or its compound (s) and need all, even inaccessible surfaces are equally effective.

This task is solved by plastic bodies with a Content of one or more oligodynamically active Me tallen or metal compounds as an active ingredient are characterized in that the active ingredient in the form of discrete Particle is embedded in the plastic, being the active ingredient amount not more than 0.5% by weight based on the total amount weight of the plastic body and the maximum of Particle size distribution of the active substance below 500 nm lies.

Well-handled active ingredients of all kinds in powder form only with finenesses down to the micrometer range provides and offered. The specific waiter achieved with it area is, for example, for the finest commercially available Silver powder with a nominal grain size of 2-3.5 µm, that of course, a certain one, inevitable due to the process share of coarser and sub-micrometer particles indicates, according to the manufacturer, about 0.5 to 1 m² / g. Other, often used and also cheaper silver powder have even coarser particles and accordingly smaller ones specific surfaces.  

In general, even finer preparations than colloids can can only be shown as brine or gels. Here is the So given proportion of protective colloid in the further sequence processing and application usually with considerable, unwanted side effects. They are also derar colloidal preparations are often not very stable and moreover often relatively expensive.

The plastic body according to the invention are therefore before preferably made so that the blank by means of a chemical or physical process using the bactericidal and / or fungicidal (oligodynamically) active substance layers, the coated blank obtained (preliminary product) crushed and / or melted, from which then according to usual Process the desired plastic body is made.

With physical, but also with chemical processes of Coatings of surfaces can be very thin and, depending after process control, fine or even extremely fine structure structure of the deposited material can be achieved, which correspond to the delicacy of colloidal forms of preparation or at least get close. This applies in particular if the deposited layers are very thin.

With such coatings, z. B. already pure nerically from the outer geometry with a layer thickness of 10 nm already z. B. for the deposition of silver a min Minimum surface area of 19 m² / g. Preferential the layer thickness is 1 to 50 nm.

Are those surfaces also taken into account? that is perpendicular to the main surface by still open grain boundaries and fissures on the surface due to errors in the uniformity of the deposition, practically results for the specific surface even greater value.  

The maximum of the particle size distribution is preferably of the active ingredient below 100 nm, more preferably at 10 nm. With thin layers, the grain size can also be smaller than 1 nm.

Crystalline materials (PTFE, some polyimides) must e.g. B. be crushed by grinding; Melting is included (practically) not applicable. You will then by z. B. (Pressure) sintering brought into the desired shape.

example

In one for the anti-reflective coating of optical glasses The high vacuum system was about 80 cm² large films 0.25 mm thick made of polyurethane with a silver layer of about 10 nm thick. The silver layer showed no inherent structure under light microscopy, it was just that Bumps in the film as bumps in the layer to recognize. The foils were then crushed and melted while stirring at approx. 240 ° C. From that were manufactured by hot pressing test specimens (small platelets).

The silver content of this comes from the steamed silver foils The test specimen was placed after digestion with saltpetre acid determined by the AAS method to about 350 ppm where however, due to imperfections in the accessories preparation of the samples, considerable scatter between the (three) measured values had to be accepted.

In terms of magnitude, this result is only 1/30 of those values that are necessary for the effective use of Silver powder in the prior art as at least necessary will give.

These test specimens were shown to be antimicrobial against the Colonization with the Staphylococcus epidermidis bacterium fully effective. This test was carried out according to the procedure described in DE-C-42 26 810 described procedures performed.  

From this result it can be deduced that plastics with a low but finely dispersed content of Me tallparticles (or also particles from metal compounds) with a correspondingly large specific, active surface in effect are equivalent to plastics that a much higher, but less finely dispersed Content of metals (or metal compounds) with accordingly, smaller specific, active surface exhibit.

As indisputable, however, the one that is decisive for long-term effects The supply of these active substances for coarser particles Larger, it can be a further benefit from before plastics produced leads that these plastics for particularly critical Use cases through suitable process control at Her Position of the layer of metal (or metal compound gen) can be equipped with particles, their size for an optimal long-term effect from the outset is flowable.

As tested in the experiment, this coating can be applied to Fo lien, which are then shredded and processed further can be processed. Of course, it can also be reason just as good on fibers or, in principle, everyone if, on granules, with the same result of manufacture the desired final concentration of the active ingredient in art fabric are applied.

Claims (8)

1. Plastic body containing one or more bactericidal and / or fungicidally active metals and / or metal compounds as an active ingredient, characterized in that the active ingredient is embedded in the plastic in the form of discrete particles, the amount of active ingredient not exceeding 0.5 % By weight, based on the total weight of the plastic body, and the maximum of the particle size distribution of the active ingredient is below 500 nm. 2. Plastic body according to claim 1, characterized net that it is made of thermoplastic, by casting, injection molding, extrusion or the like che process can be brought into the desired final shape can. 3. Plastic body according to claim 2, characterized net that he polyethylene, polypropylene, polyamide, Po lycarbonate, polyurethane, tetrafluoroethylene / hexafluor propylene copolymer, thermoplastic polyimides, silicone and / or their Contains mixtures or copolymers. 4. Plastic body according to claim 1, characterized net that he be made of non-thermoplastic stands by sintering or pressure sintering in the ge desired final shape must be brought. 5. Plastic body according to claim 4, characterized net that it contains PTFE or (linear) poly-imides. 6. Plastic body according to one of claims 1 to 5, there characterized in that the bactericidal and / or fun gicidal metal is silver, copper, gold, zinc or cerium.   7. The method according to any one of claims 1 to 6, characterized ge indicates that the maximum particle size ver division is below 100 nm. 8. Process for producing the plastic body after one of claims 1 to 3, characterized in that to make a plastic blank using a chemical or physical process with the bactericidal and / or coated with a fungicidally active substance obtained coated blank crushed and / or melts, from which then the usual ge desired plastic body is produced.