NZ337062A - Cork stopper comprising at least two sections adhered together - Google Patents

Description

% Manufacturing process for cork stoppers and stoppers manufactured bv such a process The present invention concerns a process for manufacturing cork stoppers and the corks manufactured accordingly.

The corking of bottles containing quality wines is achieved by means of natural cork stoppers, traditionally manufactured from boards removed from cork oaks prepared by full stripping 9 to 11 years beforehand, said board being converted into strips, the width of which corresponds to the length of the corks and the thickness is at least equal to their diameter.

The manufacture of the corks is entrusted to subcontractors who cut them from each natural cork strip with a knife-edge tube cutter-cutting machine.

In order to minimize the manufacturing cost of the corks, the subcontractors' workshops are usually located in low labor cost areas, distant from the cork oak plantations, which in turn not only generates material transportation costs, but also hinders 15 material follow up throughout the manufacturing process.

In addition, during the transportation and storage at the subcontractors' facilities, the cork may be exposed to environmental damage or contamination which may lead to the production of mold and foul smells, which, if the corks are not properly cleaned afterwards, may affect the quality of the wine.

The cork manufacturing process efficiency is rather low, around 30%, and the scrap is reclaimed in the form of particle cork which is a material unsuited for contact with high grade wines.

Though particle cork stoppers fitted at both ends with natural cork sections in order to avoid any contact between the wine and the particle cork have been proposed in 25 European patent applications EPA-0 100 302 and EP-A-0 481 155 these corks have not, to the knowledge of the applicant, been adopted for the corking of bottles containing quality wines.

In the French patent application FR-A-2 636 264, a manufacturing process was also proposed which consists in cutting the corks from a very long natural cork cylinder. This 30 process, however, remains very close to the traditional process outlined above and retains its shortcomings.

% It should also be pointed out that it is common practice, using cork particles, to fill in the pores of natural cork stoppers when these pores are liable to cause corking failures. These particles, however, may end up in the wine, which is of course undesirable.

The object of the present invention is a new method for manufacturing corks 5 applicable to the corking of bottles containing quality wines and less costly than natural cork stoppers manufactured in accordance with the traditional process described above.

The method of the invention is characterized by the fact that it comprises the steps consisting of: - stack and bond by application of a food compatible adhesive natural cork plates, 10 the added thicknesses of which corresponding to the length of the corks; - cut out the corks from the plates so assembled The object of the invention is also a cork characterized by the fact that it is made of at least two layers of natural cork, butted and united by bonding with a food compatible adhesive.

A cork made in accordance with the invention may be advantageously made up of 15 three abutted natural cork sections bonded with a food compatible adhesive, the natural cork section intended for contact with the wine being preferably no shorter than one-third of the length of the cork.

As a result of the invention, it is possible to use cork from cork oaks where the bark thickness is smaller than the standard diameter of the corks, hence less expensive. 20 The production of cork is thus easier to regulate.

Furthermore, the cork cutting operation in accordance with the invention may be fully automated, with a more efficient use of material and scrap reduction, in a plant near the cork oak plantations, hence without the drawbacks associated with labor costs, transportation and follow-up of the material.

Other features and advantages of the present invention will appear by reading the following detailed description, concerning a non restrictive example of implementation of the invention related process, and examining the attached drawings, where: - figure 1 illustrates the traditional cork manufacturing process, - figure 2 represents a cork made by the traditional process, - figure 3 illustrates a cork manufacturing process in accordance with the invention, and - figure 4 represents a cork made following such a process.

V On figure 1, a cork oak bark strip 1 is represented, said strip being used to manufacture natural cork stoppers according to the traditional process. The bark strip 1 has a crust 2 on its upper face, and its width is equal to the length of the corks to be made. The cork length is standardized, usually equal to 38, 45, 49 or 52mm.

The corks are consecutively form cut by means of a special machine fitted with a knife-edge tube cutter spinning on its axis.

The relative motion of the bark strip 1 and the tube cutter 3 with respect to each other is driven manually and the manufacturing tolerances are usually plus or minus 0.5mm for a basic diameter of 24mm.

The wall thickness of the tube cutter 3 should be as thin as possible for its outer diameter to be smaller than the bark strip thickness. Because of their thinness, tube cutters are prone to wear and oval wear, leading to increased manufacturing tolerances.

Figure 2 illustrates a cork 4 made by the traditional process described above, associated with a system of orthogonal axes xi, xi and X3.

Axis xi corresponds to the longitudinal cork axis. The thickness of the bark 1 is measured along the axis X3.

During the corking operation, the cork 4 is compressed radially until its diameter is reduced to about 15mm which is around 65% of its basic diameter.

Once released in its place in the bottleneck, the cork 4 tends to return elastically to 20 its basic diameter.

As the standard diameter of a bottleneck is 21mm, thus smaller than the basic cork 4 diameter, the cork does not retrieve its basic diameter but remains compressed radially in the bottleneck, which permits achieving tight sealing.

The time needed for the cork 4 to spring back from a diameter of 15mm to a 25 diameter of 21mm (i.e. 87.5% of its basic diameter) is about ten seconds.

This length of time may constitute a limiting factor in the bottling rate as the bottles cannot be laid down as long as the sealing is not tight.

Now let us describe an example of implementation of the process according to the invention, as referring to Figures 3 and 4.

The original cork boards are boiled, sorted, stripped, straightened and then cut into rectangular plates 5, 6 and 7 having identical side dimensions and having a combined thickness equal to the length of the corks 10 to be made.

V In order to optimize the manufacture according to the corks to be made, it may be profitable to slice a thick corkboard longitudinally to produce two thinner boards.

These plates 5, 6 and 7 are stacked and assembled after being coated with food compatible adhesive in order to produce a parallelepipedic cork block 11.

On Figure 3, the layers of adhesive are designated by the references 8 and 9.

Any non-toxic glue presenting enough adherence to resist the uncorking pulling force can be used as food compatible adhesive.

Bonding of plates 5, 6 and 7 may for instance be performed by hot pressing.

It should be noted that manufacturing the cork block 11 by assembling several 10 plates 5, 6 and 7, previously cleaned individually allows, for the same cork volume, a better elimination of impurities than in the process described before, because the cork surface exposed to the cleaning agents is greater.

After cutting each cork 10 is made up, in the example described here, of three natural cork sections deriving respectively from plates 5, 6 and 7 abutted and 15 assembled by means of adhesive layers 8 and 9.

The cork cells are approximately oriented in each plate 5, 6 or 7 of cork block 11 as in the bark strip 1 described in reference to Figure 1, as each plate is produced by cutting a natural cork board in the same manner as the bark strip 1.

Referring to the system of axes xi, X2 and X3 mentioned above, it can be noted that 20 every cork 10 in accordance with the invention is cut with its longitudinal axis parallel to axis X3, in other words, it is not cut from the body of the cork board using a tube cutter orientated parallel to the board plane, as in the former process, but perpendicular to the board plane.

The resulting orientation of the cork cells in cork 10 is different and proves to be 25 more beneficial.

Indeed, after being compressed radially, the cork returns elastically to its basic diameter faster and the length of time needed to achieve tight sealing is thus reduced.

Comparative tests were run on cork specimens of a given volume, some being made up of natural cork cubes, cut from the bark, and others of cork blocks 11 in 30 compliance with the invention.

The one-piece cork specimens were compressed along axes X2 and X3 to stimulate the radial compression of well known corks 4 whereas the other specimens were compressed along axesxi, and X2 to stimulate the radial compression on corks 10 in compliance with the invention.

It was noted on the one hand that the time for the specimens compressed along the axes X2 and X3, to retrieve elastically a volume equal to 87.5% of the initial volume was about twice that needed by the specimens compressed along the axes xi and X2 and on the other hand that the force needed to compress radially the corks 10 was lower than the force needed to compress radially the corks 4, thus producing less deterioration of the cork cell structure.

Cutting corks 10 from cork blocks 11 is easily automated and can be accomplished with a higher efficiency and lower manufacturing tolerances than is possible with the traditional process. In addition, thicker walled tube cutters can be used, hence more resistant and less prone to oval wear, as the cylinder thickness is no longer limited by the bark thickness.

Several tube cutters, set up side-by-side, can be used expediently to cut several corks 10 simultaneously from a cork block 11, for example more than twenty-five corks, for example thirty corks 10, the relative motion of the tube cutters and of the cork block 11 being preferably driven automatically and not manually as it is the case in the traditional process.

As a result of the invention, corks can now be made with a basic diameter of 24.2mm for instance, and with a tolerance of only plus or minus 0.2mm can now be made. The possibility of making corks 10 with a basic diameter of 24.2mm enables an improved corking quality for an identical cork springback time.

The thickness of every plate 5, 6 or 7 is by preference less than or equal to 24mm, which allows using thinner natural cork, less expensive than the cork used for the manufacture of corks by the traditional process.

By preference, the thickness of the natural cork section which is in contact with the wine is selected so as to keep the wine from reaching the adhesive, and the length of this section is, for instance, equal to at least a third of the cork length 10.

As explained above, the cork can be cleaned in better conditions and the risk of developing molds which may impregnate it with odors and affect the quality of the wine is Furthermore, it is possible to vary the cork quality of each of the plates 5, 6 and 7 and so choose for the natural cork section meant to be in contact with the wine a better quality cork.

Taking advantage of the cork qualities of each plate and their relative orientation, it is possible to avoid having to fill in the pores of the cork, thus eliminating the risk of finding cork filling particles end up in the wine.

Of course, this invention is not restricted to the description above.

In particular, stacking any number of natural cork plates, higher than or equal to two is not outside of the domain of application of the invention. %

Claims (7)

1. Cork stopper manufacturing process, characterized by the fact that it comprises the steps consisting of: 5 - stack and bond, by means of a food compatible adhesive (8, 9), natural cork plates (5, 6,7) the combined thicknesses of which correspond to the length of the corks (10) to be made; - cut the corks (10) from the plates so assembled, perpendicular to their plane.

2. Process in accordance with Claim 1, characterized by the fact that there are three 10 plates (5, 6 7).

3. Process in accordance with either Claim 1 or 2, characterized by the fact that the assembled plates (5, 6, 7) make up a parallelepipedic block (11), the dimensions of which allow for the cutting of at least twenty-five corks (10), preferably thirty.

4. Process in accordance with any of the above claims from 1 to 3, characterized by 15 the fact that the corks are cut simultaneously.

5. Cork stopper, characterized by the fact that it consists of at least two sections (5,6, 7) of natural cork, abutted and assembled by means of a food compatible adhesive (8, 9), each natural cork section having been cut from a natural cork board by means of a knife edge tube cutter, oriented perpendicular to the plane of said board. 20

6. Cork according to claim 5, characterized by the fact that it consists of three natural cork sections (5, 6, 7), abutted and assembled by means of a food compatible adhesive, where the section destined to come in contact with the wine is of a length superior or equal to one-third of the cork length (10).

7. Corks according to either one of claims 5 and 6 characterized by the fact that each 25 natural cork section is less than 24mm in length. SND 0F CLAIMS