EP1358370A1

EP1358370A1 - Process for the manufacturing of a cork yarn, yarn and fabric thereby obtained

Info

Publication number: EP1358370A1
Application number: EP02712254A
Authority: EP
Inventors: Anna Grindi
Original assignee: Grindi Srl
Current assignee: Grindi Srl
Priority date: 2001-01-15
Filing date: 2002-01-15
Publication date: 2003-11-05
Anticipated expiration: 2022-01-15
Also published as: PT1358370E; ITRM20010016A1; WO2002055767A1; EP1358370B1; ATE272136T1; ITRM20010016A0; DE60200833D1

Abstract

Process for the manufacturing of a cork yarn (20) which retains the properties of cork yet can easily be woven, comprising the steps of: providing a thin linenized cork (1), comprising a cork layer (2) and a sheet-shaped support (3), said cork being held spread and tensioned according to a preferential direction; performing a plurality of cuts parallel thereamong and to said preferential direction, so as to cut the full thickness of the linenized cork in a direction substantially perpendicular thereto, said parallel cuts being performed at a distance between adjacent cuts not exceeding the thickness (5) of the cork layer (2) multiplied by one hundred, obtaining a strip-shaped cork yarn; and winding said strip-shaped yarn, kept tensioned, on a reel (21).

Description

PROCESS FOR THE MANUFACTURING OF A CORK YARN, YARN AND FABRIC THEREBY OBTAINED

DESCRIPTION The present invention relates to a process for the manufacturing of a cork yam, yam which may be subjected to weaving processes for the manufacturing of fabrics and linens thereby obtained.

As it is well known, cork is renewably obtained from the bark of some trees, in particular the cork oak, i.e. without uprooting them. It has some interesting properties such as resistance, impermeability, imputrescibility, remarkable elasticity and it is also insulating.

For this reason, as well as for its being easy to manufacture by cutting operations, cork can be used in several fields. One of the most common is its reduction in thin sheets which are adhered to an adhesive linen, obtaining linenized cork sheets that can be employed, e.g., as wallpaper, upholstery or for suitcases, etc. This kind of sheets, which are some tenths of millimetre thick, when folded gets creased, losing most of its pleasant appearance. Furthermore, cork is somehow paper-like rough to the feel.

In order to overcome this drawback, a process has been advanced for softening the cork surface making it similar, to the feel, to that of a soft leather, like chamois, velvet or alcantara.

This improvement of the tactile sensations coincided with an improvement of the mechanic properties of the cork layer thus treated, which has become substantially crease-resisting.

These advantages, taught in the laid-open International Application WO 99/41050 (Grindi) have allowed the processing of cork in the modes and employs known for the high-quality leather, yet not in those typical of fabrics.

In fact, due to the intrinsic water-proofhess of cork, also the fabric layer thus treated totally lacks breathability. Moreover, unlike hides, yams enjoy a broad versatility of use. Further, an accidental tearing or shearing of a linenized cork sheet would entail the loss of the entire sheet, whereas the breaking of a yam merely entails the loss of a yarn section.

These drawbacks impeded the transfer of the qualities of cork, in particular of softened cork, to all the textile sectors.

The technical problem underlying the present invention is to provide a manufacturing process to avoid the drawbacks cited with reference to the state of the art.

Such problem is solved by a manufacturing process comprising the steps of: * providing a thin linenized cork, comprising at least one cork layer and a sheet- shaped support made of cloth, said linenized cork being held spread and tensioned according to a preferential direction;

* performing a plurality of cuts parallel thereamong and to said preferential direction, so as to cut the full thickness of the linenized cork in a direction substantially perpendicular thereto, said parallel cuts being performed at a distance between adjacent cuts not exceeding the thickness of said at least one cork layer multiplied by one hundred, obtaining a strip-shaped cork yam; and

* winding said strip-shaped yarn, kept tensioned, on a reel. The overall thickness of the cork layer is of about one tenth of a millimetre and, advantageously, said distance between adjacent cuts does not exceed said thickness multiplied by thirty.

According to preferred embodiments of the present process, the strip-shaped yam can be kept planar or hehcoidally twisted. Moreover, the latter can be coupled to a yarn sewn longitudinally thereto, in order to improve its consistency and workability and to abut several sections thereof.

The main advantage of the process according to the present invention lies in obtaining a cork yarn which retains its properties yet can easily be woven.

For such features, the cork yarns thereby obtained are employable in dressmaking and drapery.

The present invention will be described herebelow according to some variations of a preferred embodiment thereof, given as a non-limiting and outlining example. Reference will be made to the figures in the annexed drawings, wherein:

* figure 1 shows a perspective view of an apparatus for the cutting of linenized corks for the process according to the present invention;

* figure 2 shows an enlarged view of a section of a linenized cork employed in this process;

* figure 3 shows an enlarged perspective view of a first variation of a yam obtained according to the present process; and * figure 4 shows an enlarged perspective view of a second variation of a yam obtained according to the present process.

In the present process, a linenized cork, indicated with 1 in the figures, i.e. a sheet made of leaves comprising a cork layer 2 uniformly spread over the entire surface thereof (figure 2) is provided. A likewise linenized cork 1 is of the type comprising a cork layer 2, of reduced thickness, and a supporting layer 3 to which the cork layer 2 is adhered.

This linenized cork 1 can be provided by virtue of a complementary process including a step of cutting the raw cork into very thin leaves, of a thickness ranging from 0.05 to 1.00 mm. These leaves are placed edge-to-edge, thereby determining a substantially homogeneous layer 2.

In this step, alike corks may be employed in order to obtain a flat surface, or different corks may be colour-matched thereamong.

The layer 2 formed by a distribution of said leaves is made to adhere on a supporting layer (cloth) 3, at an adhesive surface 4 of the latter.

The thickness 5 of the cork layer 2 obtainable will be that of the leaves deposited onto the sheet-shaped support, i.e., ranging from 0.05 to 1.00 mm, preferably from 0.05 to 0.20 mm.

According to a preferred variation of the present embodiment, the thickness 5 is substantially equal to 0.10 mm.

In order to complete the adhering, the cork layer 2 and the sheet-shaped support 3 can be pressed one against the other. The glue employed may be of a heat-actionable and/or pressure-sensitive kind and it should be evenly spread onto the adhesive surface 4 of the sheet-shaped support 3.

Said glue could be, e.g., a heat-activated lacquer, like a polyvinyl and/or polyurethane adhesive. In this case, the cork leaves and the sheet-shaped support 3 can be pressed together by passing them between heated rolls at a temperature of about 70-100°C.

Any unevenness due to the overlapping of the edges of the cork leaves could be eliminated by abrasion, obtaining a smooth cork surface 6 and a surface covered by the sheet-shaped support, called linenized surface 7. Advantageously, said sheet-shaped support 3 is provided in form of strip, hence also the linenized cork 1 will be manufactured in form of strip, optionally available in a reel 10 (figure 1).

Among the preferred sheet-shaped supports there are those apt to give optimum mechanic properties, like tensile strength, to the cork leaves. E.g., the sheet-shaped support 3 could be made of cotton, viscose, silk, polyester, etc.

The above could also apply to a variation of the present process, wherein the linenized cork comprises more than one cork layer, e.g., a pair of cork layers partitioned by a sheet-shaped support, so that both linenized faces be cork surfaces.

The steps of the process disclosed herebelow refer to the linenized cork comprising one cork layer, however, by modifications within the reach of a person skilled in the art, they could refer to a more complex linenized cork, e.g., of the type having two cork layers partitioned by a sheet-shaped support. Upon being manufactured, according to a preferred embodiment of the present example, said linenized cork 1 could be subjected to a softening treatment, thereby giving to the cork a skin-like tactile response, moreover making it resistant to creasing and therefore foldable for an undetermined number of times, without thereby reducing the tearing strength thereof.

According to this treatment, an emollient agent comprising surfactants is provided.

Such an emollient agent can, e.g., be obtained mixing, in an appropriate proportion, substances having a chemical affinity with cork, in particular glycerol and emollient lipids, with a quantity of surfactants.

A proportion serving the purposes ranges f om 5:1 to 1:1 and it is preferably equal to about 3:1.

Preferably said emollient lipids are natural lipids having an animal or vegetal origin, and comprise, advantageously but not exclusively, mink oil, cocoa oil and aloe extract.

The abovecited surfactants are preferably of the emollient and/or softening type (Em type and Sp type).

The abovedescribed emollient agent is diluted with water, preferably with demineralized water having a hardness not greater than 0,5°F (French degrees). The dilution, through with an emollient mixture is obtained, occurs with a predetermined water/emollient agent proportion, to give to the mixture the needed emollient properties for linenized cork sheets.

Preferably, said proportion ranges from 12:1 to 8:1, in particular equal to about 10:1, however it can vary with the use of concentrated emollient agents. Then, the treatment according to the invention includes a step wherein an absorbing layer sheet, apt to be soaked with liquid and flexible to be put in contact with the linenized cork 1 to be softened. For this reason, the layer has adequate dimensions as to cover an entire cork sheet.

An absorbing layer serving this purpose is, e.g., a fabric layer, preferably a thick weft cotton layer.

According to an analogous application, the absorbing layer could be replaced, as it will be made apparent hereinafter, by the sheet-shaped support 3 applied to said cork layer 2, provided that the cloth of said sheet-shaped support 3 have an absorbent power apt to hold the demineralized water/emollient mixture. Needwise, a layer can instead be obtained by the approaching and/or the overlapping of several fabric sheets. hi the softening treatment, the absorption of the emollient mixture in the absorbing layer or in the absorbing sheet-shaped support is induced by immersion in a bath realized with said mixture.

For the absorption of the mixture, and in particular of the emollient agent in the layer to be adequate, the immersion period has a length greater than 1 hour, preferably equal to about 2 hours.

In case the layer be employed, upon having been soaked it is put in contact with the linenized cork 1, optionally, but not exclusively, at the linenized surface 7 thereof. In the case the cloth of the sheet-shaped support has been soaked by immersion of the entire linenized cork 1, the coupling therebetween is already automatically implemented.

Subsequently, the cork surface 6 can be partially isolated by limiting, yet not eliminating, the circulation of the atmospheric air thereto.

The isolation can occur by covering said cork surface 6 with a further layer which is at least partially air- and water-proof. An advantageous system to isolate the cork surface 6 and to concomitantly treat the linenized cork surface 7 in a single operation, is that of rolling up the linenized cork 1 and the layer forming a roll, optionally employing a suitable reel.

According to the present process, the layer is to be kept in contact with the linenized cork 1 for a period of time having a length greater than 24 hours, so as to allow the drying thereof. The same principle applies in the case wherein the sheet- shaped support has been soaked.

In fact, in this period of time the absorbing layer substantially dries up by the evaporation of the emollient mixture, i.e. of the aqueous fraction thereof.

According to a variation, the roll of linenized cork is vertically placed on top of a support allowing the free (natural or forced) circulation of air having a relative humidity lower than 50% and at a temperature ranging from 18° to 23°C.

During the drying, with the progressive increase of concentration of the emollient substances and of the surfactants, the substances are absorbed at the linenized and non-linenized surfaces 6, 1, of the linenized cork 1, whereas the action of the surfactants increases the penetration and the softening effectiveness of the emollient substances.

At the end of the drying, the roll can be unwound, with optional removal of the layer that can subsequently be used again.

The linenized cork 1 thus obtained can be wound on a reel, abovecited and indicated with 10 in the figures (figure 1).

In the step subsequent to the softening treatment, the softened and dried linenized cork 1 is unwound from the reel 10 which is placed in an elevated position. During the unwinding, the linen 1 is appropriately kept tensioned by tensioning rolls, each indicated with 11. The tension is exerted according to a preferential direction which, in the present example, is the linear development of the unreeled strip. A tensioned section 8 of the linenized cork 1 is subjected to a cutting step, by suitable machines known to those skilled in the art as 'cutters'. Schematically, said cutters comprise cutting rolls 12 between which the tensioned section 8 is inletted.

Said cutting rolls 12 perform a plurality of cuts parallel thereamong and to said preferential direction, so as to cut the entire thickness 6 of the linen 1 in a direction perpendicular to the latter, i.e. to the surfaces 6, 7 thereof.

The cutting members formed onto the surface of the cutting rolls 12 perform adjacent cuts with a distance therebetween not exceeding the thickness 6 of the cork layer 2 multiplied by 100. According to a preferred embodiment, such multiplication factor does not exceed 30. The maximum useful distance is 10 mm, the minimum distance is 1.0 mm, a particularly suitable distance is 2.0 mm.

Said plurality of cuts generates a corresponding plurality strip-shaped cork yams 20, having a substantially rectangular cross section and the distance between the adjacent cuts and the thickness of the linen 1 as dimensions. hi a subsequent step, said strip-shaped yam 20 is kept tensioned and wound on a reel 21. h an optional intermediate reinforcing step, such yam 20 is associated to a reinforcing thread 22 of a material having a high tensile strength, like, e.g., nylon.

This thread 22 is applied by a sewing machine 13 longitudinally to the development of the yam 20, according to modes known to those skilled in the art. According to a first variation, the thread 22 is inserted so as to alternatively cross said surfaces of cork 6 and linenized cork 7 of the yarn 20 (figure 3).

According to a second variation, at the reinforcing step the yam 20 undergoes a twisting, thereby assuming a helix-shaped configuration. In this variation, the thread 22 can be located axially to the helix. The application of the reinforcing thread 22 will be preferred in those cases wherein the width of the yarn 20 be markedly reduced, thereby reducing the adhesive surface which keeps the cork layer and the sheet-shaped support associated therebetween.

In particular, the presence of the reinforcing thread 22 is advantageous for a distance between the adjacent cuts not exceeding the 4.0 mm.

In the abovedisclosed process besides the variations within the reach of a person skilled in the art, a further cork dyeing step could be introduced. This step could be provided prior to the softening treatment or thereafter, or even prior to the coupling of the cork layer 2 and of the sheet-shaped support 3.

According to this dyeing step, the cork is treated with a mordant, i.e. metallic salts or tannin, according to leather dyeing techniques. E.g., a useful metallic salt is kalinite.

The mordant is diluted in a bath of heated purified water. The cork, in the form of leaves, sheet or yarn, is dipped in the mordanting bath at boiling temperature and then left to cool for 24 hours.

Subsequently, the dye can be applied by a further hot bath. In order to brighten up the colour, a further mordanting can be provided, followed by a rinsing and a drying which completes the dyeing step.

Furthermore, it is understood that the order of the abovedisclosed steps could differ, in particular the softening treatment could be carried out onto cork leaves not yet adhered to the respective sheet-shaped support, or to the yarns cut according to modes analogous to the abovedisclosed ones.

The abovedescribed yam can be subjected to weaving steps to manufacture a fabric with any knitting.

This fabric can be employed in different fields like dressmaking, upholstery, coatings in general, peltry as a leather substitute, etc. In order to satisfy particular requirements and contingencies, a person skilled in the art will be able to carry out numerous further modifications and variations, without departing thereby from the protective scope of the invention as defined by the following claims.

Claims

CLAΓMS

1. Manufacturing process for the manufacturing of a cork yam comprising the steps of:

* providing a thin linenized cork (1), comprising at least one cork layer (2) and a sheet-shaped support (3), said linenized cork (1) being held spread and tensioned according to a preferential direction;

* performing a plurality of cuts parallel thereamong and to said preferential direction, so as to cut the full thickness of the linenized cork (1) in a direction substantially perpendicular thereto, said parallel cuts being performed at a distance, one from the adjacent other, not exceeding the thickness (5) of said at least one cork layer (2) multiplied by one hundred, obtaining a strip-shaped cork yam (20); and

* winding said strip-shaped yam (20), kept tensioned, on a reel (21).

2. Process according to claim 1, wherein the thickness (5) of the at least one cork layer (2) ranges from 0.05 and 1.00 mm.

3. Process according to claim 2, wherein the thickness (5) of the at least one cork layer (2) ranges from 0.05 to 0.20 mm.

4. Process according to claim 3, wherein the thickness (5) of the at least one cork layer (2) is substantially equal to 0.10 mm.

5. Process according to claim 1, wherein the linenized cork (1) is provided in form of strip, available in a reel (10).

6. Process according to claim 1, wherein said cork is subjected to a softening treatment.

7. Process according to claim 6, wherein the softening treatment is carried out onto the linenized cork (1).

8. Process according to claim 6 or 7, wherein the cork is immersed in an emollient mixture comprising water and an emollient agent obtained mixing emollient substances having a chemical affinity with cork and a surfactant.

9. Process according to claim 8, wherein said emollient substances comprise glycerol and/or emollient lipids like mink oil, cocoa oil and aloe extract.

10. Process according to claim 9, wherein the surfactant is of the Em and/or Sp type.

11. Process according to any one of the claims 8 to 10, wherein said emollient substances and said surfactant are mixed according to a proportion ranging from 5:1 to 3:1.

12. Process according to any one of the claims 8 to 11, wherein the water and the emollient mixture are mixed according to a proportion ranging from 12:1 to 8:1

13. Process according to claim 1, wherein said distance does not exceed the thickness (5) of the cork layer (6) multiplied by thirty.

14. Process according to claim 1, wherein said distance does not exceed the 10.0 mm.

15. Process according to any one of the claims 1, 13, 14, wherein said distance is substantially 2.0 mm.

16. Process according to claim 1, wherein the strip-shaped yarn (20) is associated to a reinforcing thread (22).

17. Process according to claim 16, wherein the distance between adjacent cuts does not exceed the 4.0 mm.

18. Process according to claim 16, wherein the reinforcing thread (22) is of nylon.

19. Process according to claim 16, wherein the reinforcing thread (22) is inserted so as to alternatively cross the surfaces of the strip-shaped yam (20).

20. Process according to claim 16, wherein the strip-shaped yam (20) is twisted so as to assume a helix-shaped configuration, said reinforcing thread (22) being located axially to the helix.

21. Process according to claim 1, wherein the cork is subjected to a dyeing step.

22. Process according to claim 21, wherein said dyeing step provides a mordanting of the cork prior to a dye application.

23. Process according to claim 1, wherein the linenized cork comprises two cork layers partitioned by a sheet-shaped support.

24. Cork yarn (20) manufactured by the process according to any one of the previous claims.

25. Fabric obtained by weaving the cork yarn (20) of the previous claim.

26. Use of the fabric and/or of the cork yam (20) as defined in claims 24 and 25, in the fields of dressmaking, upholstery, coatings in general, peltry as a leather substitute.