SK37094A3 - Device for uniform suspension application on collagen carrier - Google Patents

Abstract

A process for the production of a material for sealing and/or healing wounds, comprising: i) filling a liquid composition into a container having two or more plates, at least two of said plates being perforated with one or more flow-through holes and at least one of said perforated plates being movable relative to another of said perforated plates, ii) transporting a carrier below the container in a transport direction, and iii) continuously moving the perforated plates relative to each other so as to allow the liquid composition to drip on to the carrier being transported below the container, whereby the liquid composition is substantially evenly applied to the carrier. Device comprises supspension container with base frame (1) and two perforated bottom plates with proviso that two of said perforated plates include upper plate (3) movable relative to the bottom plate (2) and enables continual move of the upper plate (3) back and forth.

Description

Technical field

The invention relates to a device for uniformly applying a suspension to a carrier of collagen for the production of wound dressing and wound healing material.

The state of the art

EP 0 059 265 discloses a wound dressing and healing material consisting of a single collagen carrier which is coated with one fibrin component, one thrombin component and additions such as calcium ions, protease inhibitors or heparin antagonists.

For the manufacture of this material, individual components or additions suspended in an organic solvent such as ethanol are used and subsequently applied, for example by spraying, to the collagen carrier.

However, some problems arise because the coating suspension is difficult to process. For example, the nozzles used for liquids of this kind are immediately blocked. It is possible to use liquid-air nozzles of larger diameter, but only the nozzles with the largest diameters offered allow for trouble-free operation. However, these nozzles have one decisive disadvantage. A fuzzy delimitation of the outlet stream does not produce the desired uniform suspension layer, but a trapezoidal applied profile on the collagen carrier. This leads to considerable losses at the edges of the collagen carrier or to losses of the valuable suspension.

EP-A 472 050 discloses a device for applying a liquid film to a casting strip, which causes the liquid to be distributed from the inflow opening to a plurality of spout openings through individual liquid-distributing compartments immediately adjacent to one another.

The liquid distribution takes place in the form of a strain, namely from one hole to two, four, eight, sixteen, and so on. outlets. This device is not suitable for the uniform application of any suspension containing fibrinogen components and one thrombin component, since the multiple compartments of the liquid streams become clogged and clogged by the suspension, and this is more pronounced than when using nozzles.

It is therefore an object of the present invention to avoid the aforementioned drawbacks of the prior art methods.

This object can now be solved by the device according to the invention.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a device for uniformly applying a suspension to a carrier of collagen for the manufacture of wound dressing and healing material, wherein the device consists of a suspension container, the bottom of which consists of a base frame and a single bottom surface with openings. above the bottom surface with openings there is a movable surface with openings.

BRIEF DESCRIPTION OF THE DRAWINGS

In FIG. 1 shows the bottom of the device according to the invention, FIG. 2 shows an exemplary layout of the openings of the bottom surface, and FIG. 3 and 4 show suspension application profiles transversely to the conveying direction of the treadmill according to the invention and according to a comparative example.

EXAMPLES

The device according to the invention consists of a container provided with a rectangular bottom surface 2 in the form of a plate with openings, bounded by a base frame X on which the side delimiting walls of the container are located. Immediately above the bottom surface 2 with openings adjoins a second surface with openings which can be moved inside the container - a movable surface X in the form of a plate with openings.

The suspension that is fed into the vessel consists of one fibrin component, one thrombin component, as well as aprotinin as a protease inhibitor and other additives such as calcium ions or heparin antagonists in an alcohol such as ethanol, n- or i-propanol, or i-butanol. It is used for the production of wound dressing and healing material and is thus used for medical purposes.

For this reason, the device, in particular the areas with openings, must be made of non-abrasive material which does not react in contact with the suspension. Suitable materials are, for example, stainless steel or titanium. The side delimiting walls may also be made of glass or plexiglass, which allows good observation of the suspension in the container.

The two aperture surfaces 2, 3 each have one or more rows of apertures, the flow apertures in the rows of apertures always being equidistantly spaced. Preferably, a plurality of holes are provided on the aperture surfaces 2, 3.

The diameter of the flow orifices should be chosen sufficiently large to prevent the flow orifices from clogging with the suspension.

The ratio of the flow orifice diameters to the diameter of the largest particles of the suspension is about 5: 1 to 50: 1, preferably 7.5: 1 to 40: 1 and particularly preferably 10: 1 to 30: 1.

The largest particles are about 0.1 mm to 0.2 mm in diameter.

are in suspension

In a preferred embodiment of the device according to the invention, the flow openings have a diameter of about 2 to 3 mm.

The centers of the flow openings preferably lie at a distance of between 2 and 8 mm, particularly preferably at a distance of 3 to 4.5 mm across the application face.

Depending on the number of rows of holes, the distance between two adjacent holes in one row of holes may be up to 16 mm or more.

To apply the suspension to the collagen carrier, a pre-homogenized suspension is pumped into the vessel at a constant rate pump, initially the movable surface 3 with openings lies on the bottom surface 2 with the openings so that the flow openings are closed. The seal should be as efficient as possible and may be supported by loading the weight on a movable area with openings if necessary.

When the suspension in the container has reached a stationary level corresponding to a predetermined pump speed, the applicator is set in motion. As a result, the movable surface 3 with the openings in the longitudinal direction starts to move back and forth above the stationary bottom plate 2 with the openings. In one position - preferably in the middle between the two turning points at which the change of direction of the movable plate 3 with the holes is happening - both plates overlap and the suspension can drip onto the collagen carrier which is guided on the conveyor belt under the deposition apparatus.

The level of suspension in the deposition apparatus remains constant until a new suspension is added through the pump.

By varying the large oscillations of the movable surface 3 in the form of a plate with openings, the ratio of the open time intervals to the closed time intervals can be adjusted over a wide range. In this way, it is also possible to select hole diameters in which there are no more complications and at the same time the drip rate is limited.

Taking into account the alignment of the rows of holes and the speed of the treadmill, a droplet distribution pattern can be obtained in which the droplets form the points of equilateral triangles, corresponding to the tightest spherical layer.

The movement of the aperture plate 3 preferably takes place at right angles to the conveying direction of the treadmill. By continuously moving the movable plate 3 back and forth at the same time, the suspension is homogeneous so that a uniform distribution of the components on the collagen carrier is achieved. Alternatively, it is possible to promote mixing by an additional device on the movable surface 3 with the openings or by means of a mixer.

Another embodiment is designed so that instead of the plates, two moving tubes, one tube and one half tube, respectively, are used. The outer tube or semi-tube is preferably stationary and is provided with outlet openings at the bottom. Into this tube is inserted an inner tube which is provided with rows of openings that can coincide with the openings of the outer tube. By periodically rotating the inner tube or the half tube back and forth, the outflow openings periodically open and close to achieve the desired effect.

By means of the device according to the invention, it is possible to apply the suspension evenly at a precisely defined width to the collagen carrier without causing marginal losses to the suspension or the collagen carrier. The coating profile obtained after evaporation of the suspension medium is not rectangular, as in the spraying techniques known to date, of the trapezoidal form.

A comparative experiment in which the edge loss achieved with the spraying technique used hitherto by the liquid-air nozzle with the loss achieved with the device according to the invention has been compared shows that with the liquid-air nozzle more than 5 times the side of the suspension liquid than with the device according to the invention.

This is a relatively low productivity effort. The ratio is all the greater the larger the deployments.

The loss of suspension when applied by means of the device according to the invention is only due to the end of the pumping of the suspension due to the remaining content remaining in the container.

Example 1;

In a container with a bottom plate with openings and a movable plate with openings that have the following dimensions:

Width: 450 mm

Depth: 12 mm

Number of rows of holes: 2

Outlet diameter: 2 mm

Distance between centers of two outlets in one row: 8 mm

Spacing between rows of holes: 6.9 mm (alignment of the outlet holes is shown in Fig. 2), with closed well plates suspended from 55 mg / ml fibrinogen 20 IU / ml thrombin and 0.71 Ph.Eur.U. / ml aprotinin in ethanol at a rate of 450 ml / min until a stationary liquid height of 50 mm was reached. At this point, a movable plate was set in motion with holes of 400 cycles / min, with a 6 mm swing in both directions. The suspension dripped at 450 mm width onto the collagen sponge from a 5 mm height, which was transported by means of a treadmill at a speed of 1 m / min. at right angles to the movement of the movable plate under the container. The evaporation of the suspension liquid was no7

9 collagen coated with about 5.5 mg / cm2 fibrinogen 2 IU / cm2 thrombin and 0.071 Ph.EUr.U./cm2 aprotinin.

The marginal loss was below 1%.

The application profile transversely to the conveying direction of the treadmill is shown in FIG. Third

Comparative example:

Again, a suspension of the same composition was applied at a width of 450 mm on a collagen carrier that had been transplanted on the conveyor belt. Figure 4 shows the best result of numerous experiments with different liquid-air jets.

In this example, a combination of Spraying Systems Inc. nozzles was used. with a change of plate. Of the many specimens of the same type, the best specimen was chosen.

The application profile transversely to the conveying direction of the treadmill is shown in FIG. 4 and shows the distribution of fibrinogen transversely to the conveying direction of the treadmill. The loss on both sides of the dropping amount was still about 20% under these conditions.

Claims (6)

PATENT CLAIMS Apparatus for uniformly applying a suspension to a collagen carrier for producing wound dressing and healing material, characterized in that the device consists of a suspension container, the bottom of which comprises a base frame (1) and a bottom surface (2) with openings, wherein a movable surface (3) with openings is located directly above the bottom surface (2) with openings. Device according to claim 1, characterized in that the bottom surface (2) with openings and the movable surface (3) with openings each have at least one row of equidistantly spaced outflow openings. Apparatus according to claim 1, characterized in that the bottom surface (2) with the openings and the movable surface (3) with the openings have more than one row of outlet openings, the center of the openings being slanted in the direction of travel of the treadmill spacing 2 to 8 mm, preferably 3 to 4.5 mm. Apparatus according to claim 1, characterized in that the ratio of the diameter of the flow holes to the diameter of the largest particles of the suspension is 5: 1 to 50: 1, preferably 7.5: 1 to 40: 1 particularly preferably 10: 1 to 30: 1 . Device according to claim 1, characterized in that the movable aperture surface (3) is adjustable relative to the bottom aperture surface (2) for controlling the flow of the suspension. Apparatus according to claim 1, characterized in that the container is in the form of a tube or semi-tube at the bottom provided with outflow openings into which a perforated tube or semi-tube is movably adjustable.