PRINTED AND COATED RELEASE FOIL

Abstract

The invention relates to a release foil comprising a substrate layer, a printed image and a release coating, wherein the the printed image is arranged at least partially between the substrate layer and the release coating, wherein the printed image includes at least one dye that is cured by UV radiation, and wherein the release coating includes a polysiloxane that is cured by UV radiation.

Claims

1. A release film comprising a carrier layer, a printed image and a release coating, wherein (a) the printed image is disposed at least partly between the carrier layer and the release coating; and (b) the printed image comprises at least one ink cured by UV radiation; and (c) the release coating comprises a polysiloxane cured by UV radiation and has a surface weight of <5 g/m.sup.2.

2. The release film as claimed in claim 1, wherein the printed image borders both directly onto the carrier layer and directly onto the release coating.

3. The release film as claimed in claim 1, wherein the printed image is disposed completely between the carrier layer and the release coating.

4. The release film as claimed in claim 1, wherein the carrier layer comprises a polyolefin.

5. The release film as claimed in claim 4, wherein the carrier layer comprises a polyolefin which is selected from the group consisting of thermoplastic olefins; and/or thermoplastic olefin homopolymers or copolymers of ,-unsaturated olefins having 2 to 10 carbon atoms; preferably selected from the group consisting of polyethylene, polypropylene, polybutylene, polyisobutylene (PI), copolymers and/or mixtures of at least two of the stated polymers.

6. The release film as claimed in claim 1, wherein the carrier layer is colored.

7. The release film as claimed in claim 1, wherein the carrier layer has a layer thickness in the range from 5 m to 50 m.

8. (canceled)

9. (canceled)

10. (canceled)

11. (canceled)

12. (canceled)

13. The release film as claimed in claim 1, wherein the release coating is based on at least one cured polysiloxane which is selected from the group consisting of polysiloxanes which are addition-crosslinked, condensation-crosslinked, radically crosslinked, and cationically crosslinked.

14. The release film as claimed in claim 1, wherein the release coating is based on at least one cured polysiloxane which is selected from the group consisting of polydialkylsiloxanes, and polyalkylarylsiloxanes.

15. (canceled)

16. The release film as claimed in claim 1, having (a) surface layer(s) as a silicone coating on one side or both sides.

17. The release film as claimed in claim 1, wherein the ink cured by UV radiation comprises a fluorescent dye or a luminescent dye.

18. The release film as claimed in claim 1, which, on the reverse side of the carrier layer, facing away from the printed image, comprises at least one further layer and/or a further printed image.

19. The release film as claimed in claim 1, wherein the release coating, the carrier layer, and also the optionally present further layer or further layers of the release film, each independently of one another, may have been furnished with adjuvants which are selected from the group consisting of antiblocking agents, antistats, antifog agents, active antimicrobial ingredients, dyes, color pigments, stabilizing agents, process stabilizers, process assistants, flame retardants, nucleating agents, crystallization agents, lubricants, optical brighteners, flexibilizers, sealing agents, plasticizers, spacers, fillers, peel additives, waxes, wetting agents, surface-active compounds, and dispersants; and/or wherein the weight fraction of the further adjuvants in each case independently of one another is at least 0.01 to 30 wt %, preferably 0.1 to 20 wt %, based in each case on the total weight of the individual layer.

20. The release film as claimed in claim 1, wherein the silicone layer in the context of the FINAT bond strength testing in accordance with the test standard FTM 10, on removal of the test adhesive tape at a temperature of 70 C., a detachment angle of 175, and a detachment rate of 300 mm/min, corresponding to release values in the range of 2 to 25 cN/10 cm, exhibits no detachment phenomena identified as rub off.

21. (canceled)

22. The release film as claimed in claim 1, wherein the printed image and/or a further printed image is or comprises a registration, control and/or print mark.

23. The release film as claimed in claim 22, wherein the registration, control and/or print mark is disposed in a marginal region of the release film.

24. The release film as claimed in claim 1, wherein the ink cured by UV radiation and/or the polysiloxane cured by UV radiation are/is radically or cationically cured.

25. A packaging for a hygiene article, comprising a release film as claimed in claim 1.

26. (canceled)

27. A method for producing a release film as claimed in claim 1, comprising the steps of (a) printing at least part of the surface of a carrier layer with at least one ink curable by UV radiation; (b) irradiating the curable ink with UV radiation; (c) applying a coating composition which comprises a polysiloxane curable by UV radiation to at least part of the printed surface of the carrier layer; and (d) irradiating the curable polysiloxane with UV radiation; wherein step (d) is carried out not later than 300 seconds after step (b).

28. (canceled)

29. (canceled)

30. The method as claimed in claim 27, wherein the method is further characterized by one or any combination of the following: (i) both the ink for the printed image and the release coating are printed in direct succession in a single, joint operation; (ii) the machine speed is in a range from 100 to 800 m/min; (iii) the machine speed is in a range from 200 to 450 m/min; (iv) the UV radiation used in step (b) has substantially the same wavelength as the UV radiation used in step (d): (v) the ink curable by UV radiation is radically curable and the polysiloxane curable by UV radiation is radically curable; (vi) the ink curable by UV radiation is radically curable and the polysiloxane curable by UV radiation is cationically curable; (vii) the ink curable by UV radiation is cationically curable and the polysiloxane curable by UV radiation is radically curable; (viii) the ink curable by UV radiation is cationically curable and the polysiloxane curable by UV radiation is cationically curable; (ix) the ink curable by UV radiation comprises a solvent and the polysiloxane curable by UV radiation comprises a solvent; (x) the ink curable by UV radiation comprises a solvent and the polysiloxane curable by UV radiation is solvent-free; (xi) the ink curable by UV radiation is solvent-free and the polysiloxane curable by UV radiation comprises a solvent; (xii) the ink curable by UV radiation is solvent-free and the polysiloxane curable by UV radiation is solvent-free; (xiii) steps (a) to (d) are carried out under protective gas atmosphere; or (xiv) steps (a) to (d) are carried out without protective gas atmosphere.

31. (canceled)

32. (canceled)

33. (canceled)

34. (canceled)

35. (canceled)

Description

[0120] FIG. 1 illustrates schematically a preferred embodiment of the release film of the invention, comprising carrier layer (1), printed image (2), and release coating (3). In the embodiment of FIG. 1 the release coating (3) is applied over the full area to the carrier layer (1), including the printed image (2), and so the area of the release coating (3) corresponds to the area of the carrier layer (1).

[0121] FIG. 2 illustrates schematically a preferred variant of the release film of the invention, comprising carrier layer (1), printed image (2), and release coating (3). In the embodiment of FIG. 2 the release coating (3) is applied over part of the area to the carrier layer (1), including the printed image (2), and so the area of the release coating (3) is smaller than the area of the carrier layer (1); a marginal region (4) remains, which is not covered with the release coating (3).

[0122] FIG. 3 illustrates schematically a preferred variant of the release film of the invention, comprising carrier layer (1), printed image (2), and release coating (3), which as well as the printed image (2) in the marginal region (4) has a registration, control and/or print mark (5).

[0123] FIG. 4 illustrates schematically a preferred variant of the release film of the invention, comprising carrier layer (1), printed image (2), release coating (3), marginal region (4), registration, control and/or print mark (5), with a further printed image (6) on the reverse side.

[0124] FIG. 5 illustrates schematically packaging preferred in the invention for a hygiene article and comprising the release film of the invention. This packaging takes the exemplary form of a packaging wrap for a sanitary towel, but may also be used for packaging other packaged contents, especially hygiene articles. The entire packaging preferably consists of the release film and the sanitary towel. The release film of the packaging of the invention may comprise registration, control and/or print marks, though in FIG. 5 these have been omitted for reasons of clarity. FIGS. 5A to 5D show different states of the packaging of the invention.

[0125] FIG. 5A shows the packaging of the invention in the fully unfolded state. The carrier layer (1) has a printed image, which in the state shown is concealed by the sanitary towel (7) in front of it. A skilled person recognizes that the printed image may alternatively also be disposed at an offset to the sanitary towel (7) and/or may be given such an extensive design that at least parts of it are not concealed by the sanitary towel (7), i.e., are visible. The release coating (3) is applied over part of the area to the carrier layer (1), including the printed image, and so the area of the release coating (3) is smaller than the area of the carrier layer (1); a marginal region (4) remains which is not covered with the release coating (3). Preferably on its reverse side the sanitary towel (7) has a pressure-sensitive adhesive (not shown) via which it is attached on the release coating (3). By manual removal it is possible to detach the sanitary towel together with the pressure-sensitive adhesive on the release coating (3). Subsequently, in the course of the as-intended use of the sanitary towel (7), the pressure-sensitive adhesive may serve for attaching on the inside of the underwear. On the two long sides, in the marginal region (4), the carrier layer (1) has a respective strip of pressure-sensitive adhesive (13), by which the packaging can be closed at the sides by wrapping. Preferably the packaging is reclosable. A skilled person recognizes that other possibilities can also be used, alternatively, for the closing at the sidessuch as, for example, heat sealing, crimping, etc. Preferably the sanitary towel (7) is not arranged so as to be centered relative to the carrier layer, but instead has a lateral offset, so that a region (14) protrudes beyond the sanitary towel on the margin of the carrier layer (1). The release film may be given an imaginary subdivision, via a first wrapping fold (8), into a narrow wrap section (10) and also a middle wrap section (11). Furthermore, the release film can be subdivided by a second wrapping fold (9) into the middle wrap section (11) and also a wide wrap section (12).

[0126] FIG. 5B shows the packaging of the invention in the fully unfolded state after the removal of the sanitary towel. The printed image (2) behind it is visible in this way and may serve aesthetic purposes and/or, in the form of pictograms and/or text, for example, may comprise instructions for the disposal of the sanitary towel after it has been used in the intended way.

[0127] FIG. 5C shows the packaging of the invention in the partly unfolded state. This state may occur both during the first-time opening of the packaging and also when it is reclosed. The narrow wrap section (10) in this case is wrapped (folded in) along the first wrapping fold (8), and so the further printed image (6), which in FIGS. 5A/B is disposed on the reverse side and is therefore still not visible there in the plan view shown, is disposed, according to FIG. 5C, on the front side of the packaging and therefore becomes visible in the plan view shown. The further printed image may serve aesthetic purposes and/or, in the form of pictograms and/or text, for example, may comprise instructions for the proper removal of the sanitary towel from the packaging. By way of the pressure-sensitive adhesive (13) applied in the marginal region (4), the middle wrap section (11) on the reverse side and also the narrow wrap section (10) on the front side form a kind of closed pouch, with the wrapped sanitary towel (7) reaching into the opening of said pouch. The protruding region (14) of the sanitary towel (7) is in this case not concealed by the narrow wrap section (10), and thus remains visible (on the reverse side in comparison to the representation as per FIG. 5A).

[0128] FIG. 5D shows the packaging of the invention in the fully closed state. This state may likewise occur both during the first-time opening of the packaging and when it is reclosed. The middle wrap section (11) and also the narrow wrap section (10) folded over it are in this case again wrapped (folded in) along the second wrapping fold (9), and so a different section of the further printed image (6), which in FIGS. 5A/B was disposed on the reverse side and is therefore still not visible there in the plan view shown, is disposed, according to FIG. 5D, on the front side of the packaging and therefore becomes visible in the plan view shown. The further printed image may likewise serve aesthetic purposes and/or, in the form of pictograms and/or text, for example, may comprise instructions for the proper removal of the sanitary towel from the packaging. The further printed image (6) shown in FIG. 5C is concealed in this way. Via the pressure-sensitive adhesive (13) applied in the marginal region (4), the reverse-side wide wrap section (12) and also the front-side middle wrap section (11) and also the centrally disposed narrow wrap section (10) form a kind of closed pouch, with the doubly wrapped sanitary towel (7) located in the interior of said pouch. Preferably in this case a protruding region (15) of the release film is not concealed by the wide wrap section (12), and thus remains visible and may serve, for example, as a tab for making it easier to open the packaging with the hands. A skilled person recognizes that it may be advantageous if the reverse side of the carrier layer (1), or, in the case of a multilayer film, the reverse-side outer layer of the release film shown in FIGS. 5A/B, also has, at least in the marginal region, a further release coating, so that the pressure-sensitive adhesive (13) attaches thereto and can also be detached therefrom again.

LIST OF REFERENCE SYMBOLS

[0129] 1Carrier layer [0130] 2Printed image [0131] 3Release coating [0132] 4Marginal region [0133] 5Registration, control and/or print mark [0134] 6Further printed image [0135] 7Sanitary towel [0136] 8First wrapping fold [0137] 9Second wrapping fold [0138] 10Narrow wrap section [0139] 11Middle wrap section [0140] 12Wide wrap section [0141] 13Pressure-sensitive adhesive [0142] 14Protruding region of the sanitary towel [0143] 15Protruding region of the release film

[0144] The examples below serve to illustrate the invention, but should not be interpreted as imposing any limitation.

[0145] The carrier layer used was a polyolefin film in 24 m thicknesscorona-pretreated (42 mN/n) on one side. The machine speed was 250 m/min in each case.

[0146] A conventional flexographic printing process was used, with the printing unit disposed on a central impression cylinder. The printing unit consisted of a press cylinder, which carried the printing sleeve with the print design. The ink was applied to the press cylinder with the print design by means of an engraved roll, and excess ink was stripped from the surface of the engraved roll by a doctor knife (so-called closed box knife printing unit).

[0147] Siliconization took place in a printing unit downstream of the ink printing unit (and consisting of press cylinder, engraved roll, and box knife), and was used to apply a silicone coating by printing (=silicone printing unit). In the experiments, both the ink printing unit and the silicone printing unit were secured on central impression cylinder.

[0148] The respective construction of the release films tested is summarized in the table below, with examples C-1 to C-8 being comparative examples and examples I-1 to I-5 being inventive:

TABLE-US-00001 Printed image Release coating Chemical Chemical basis of Curing basis of Curing Ex. binder Solvent mechanism siliconization Solvent mechanism C-1 Nitrocell. EtOAc thermal Acrylate UV radic. C-2 Acrylate UV radic. Acrylate UV radic. C-3 Epoxy UV cation. Acrylate UV radic. C-4 Acrylate UV radic. Epoxy UV cation. C-5 Epoxy UV cation. Epoxy UV cation. C-6 Nitrocell. EtOAc thermal Acrylate EtOAc UV radic. C-7 Nitrocell. EtOAc thermal Acrylate UV radic. C-8 Nitrocell. EtOAc thermal Epoxy UV cation. I-1 Acrylate UV radic. Acrylate UV radic. I-2 Acrylate UV radic. Acrylate EtOAc UV radic. I-3 Epoxy UV cation. Acrylate UV radic. I-4 Epoxy UV cation. Epoxy UV cation. I-5 Epoxy UV cation. Epoxy EtOAc UV cation. EtOAc: Ethyl acetate Nitrocell.: Nitrocellulose UV radic.: radical curing reaction induced by UV radiation UV cation.: cationic curing reaction induced by UV radiation

[0149] The respective number of operations and also the times required in each case for production are summarized in the table below:

TABLE-US-00002 Machine time Set-up Time between Number of for 10 000 for 10.000 printing and Ex. operations lin. m. lin. m. coating C-1 2 80 min 100 min 2 hours C-2 2 80 min 100 min 2 hours C-3 2 80 min 100 min 2 hours C-4 2 80 min 100 min 2 hours C-5 2 80 min 100 min 2 hours C-6 1 40 min 60 min <10 seconds C-7 1 40 min 60 min <10 seconds C-8 1 40 min 60 min <10 seconds I-1 1 40 min 60 min <10 seconds I-2 1 40 min 60 min <10 seconds I-3 1 40 min 60 min <10 seconds I-4 1 40 min 60 min <10 seconds I-5 1 40 min 60 min <10 seconds Machine time: Pure machine time [min] = Linear meters (reel) [m]/machine speed [m/min] Set-up time: Pure set-up time includes the insertion and removal of the film reel, the preparation of the inks, the adjustment work, cleaning work, etc.

[0150] The release force was determined at 70 C. using an electronic tearing device (resolution 0.02 N). This was done using Tesaband A 7475, 25 mm wide. The freshly siliconized specimens were provided in slabs of around six plies, around 24-29 cm long, and wrapped in black film. These specimens are then conditioned. Conditioning took place in a drying cabinet 2 h/70 C., by wrapping the slabs around the racks. This allowed the air to circulate freely through the racks and thereby heat the slabs uniformly. The samples were removed and the adhesive tape was adhered without bubbles over the areas to be tested. The adhesive tape was rolled down 4 using a Finat roller at a speed of 20 cm/s. The release film was trimmed so that a free margin of 1 cm remained in each case to the side of the adhesive tape. The samples were cut into strips of equal length (around 30 cm long) and labelled. Subsequently the samples were placed between thin metal plates and were weighed down with weights. The loading was uniform. The number of weights was dependent on the number of samples per tier:

TABLE-US-00003 No. of Number of samples/Tier weights/each 2.6 kg 12 24 11 22 10 20 9 18 8 16 7 14 6 12 5 10 4 8 3 6

[0151] This corresponded to a loading of 70 g/cm.sup.2. The samples were subsequently stored for 20 h at 70 C. in the drying cabinet and, after removal, were adhered to a metal support sheet. A stiff film strip was affixed to the test adhesive tape, and the metal support sheet was fastened in the lower clamping jaw, the stiff film strip in the upper clamping jaw, of the Zwick test instrument. After adjustment of the load cell, the test adhesive tape was peeled off at an angle of 1750 and a speed of 300 mm/min.

[0152] To determine the rub off, the siliconized film was placed flatly onto a smooth underlay. Then the silicone layer was rubbed 4-5 times using the thumb. In the case of partial detachment of the silicone film, a rub off was recorded. The test was otherwise recorded as sat..

[0153] Release values, degrees of cure, anchorage, and rub off are summarized in the table below:

TABLE-US-00004 Release values 70 C. in the Degree of cure Rub off range from 2 Printed Release silicone Ex. to 25 cN/10 cm image coating Anchorage layer C-1 + 0 + + sat. C-2 + + + + sat. C-3 + + + + sat. C-4 + + + + sat. C-5 + + + + sat. C-6 + + Rub off C-7 + + Rub off C-8 + + Rub off I-1 + + + + sat. I-2 + + + + sat. I-3 + + + + sat. I-4 + + + + sat. I-5 + + + + sat. sat.: satisfactory

[0154] As demonstrated by the experimental data above, the production of the release films in accordance with comparative examples C-1 to C-4 involves a high working effort and is consequently associated with a long working time. The release films according to comparative examples C-6 to C-8 do not show these disadvantages, but do exhibit color transfer into the silicone printing unit (contamination) and also rub off.

[0155] Conversely, the release films according to inventive examples I-1 and I-2 show no disadvantages at all. In the case of the release films of inventive examples I-3 to I-5, however, it should be borne in mind that an odor nuisance may arise from the use of cationically curing inks and/or coating compositions.