The present invention relates to a method of manufacturing an epilatory strip, and epilatory strips obtainable by said method .

Epilation is the removal of the entire hair, including the part below the skin. Pulling the hair out of the hair follicle is preferred by many people rather than depilation because the hair removal lasts longer, ranging from several days to several weeks .

Self-epilation can be performed using various types of conventional epilatory means, usually involving use of melted or heated wax. To that aspect an epilatory strip includes a thick layer of a sticky wax, which is heated in order to encapsulate and trap the unwanted hair. Once the hair has a good grip in the wax, the hairs can be ripped off securely integrated in the wax on the strip. The strip needs to be left on the skin long enough for the wax to cool and harden in order to trap the hairs with a strong adhesive force. Ripping hair off this way causes great pain, and often sticky debris from the wax is left on the skin, thereby inducing skin irritation and erythema due to content of colophony. The common approach to minimize such disadvantages is to reduce thickness of wax so that cooling can happen faster, which however compromises the efficiency of the hair removal. Thus, self-epilation may not only be painful and time-consuming, self-epilation may also be very ineffective and inflict on the skin's condition, e.g. causing various kinds of dermatitis or allergic cutaneous manifestations. Instead many people invest in epilation performed by skilled persons at high costs, e.g. using methods such as electroepilation or photoepilation . U.S. patent no. 3,470,877 describes a method for removing hairs from the skin by placing a very thin layer of pressure- sensitive fluid adhesive on the skin to encapsulate the individual hairs to be removed. A second layer of higher viscosity pressure-sensitive fluid adhesive is then spread over the first adhesive layer and pressed against it after which the second adhesive is peeled away from the skin, which carries away the hairs and the fluid adhesive. This two step method is difficult for a person to perform herself, in particular at difficult accessible skin locations, and there is a risk that the fluid adhesive flows to unintended locations prior to use.

International patent application no. WO2009/006681 relates to an epilatory strip for removing unwanted hair from skin. The strip comprises a support layer, which has an adhesive coating on it. The adhesive attaches to hair, and the coating covers a substantial portion of the area of the support layer. The epilatory strip also includes a peel-off protective layer, which covers the adhesive coating and can be removed prior to application of the strip on to skin. In order to achieve a painless non-irritating stripping of hair from the skin aloe vera and/or vitamin E is added to the adhesive, both in concentrations of up to 25 % by weight of the adhesive coating. Thus WO2009/006681 has realized the noticeable discomforts of using epilatory strips based on adhesives but provides a solution including additives in high concentrations, thereby a.o. increasing costs substantially. Even though hypersensitivity to vitamin E is scarcely reported it is a well-known realization that the more chemical compounds and the higher their concentrations in a product are, the higher is the risk that at least one of the compounds will cause contact allergic reactions. The user may even be inclined to leave the strip for longer periods to wait for the suggested beneficial pain-reducing and irritation-avoiding properties of the epilatory strip disclosed in WO2009/006681 before ripping off the hair, thereby increasing the exposure time to the skin. Thus the fewer chemical compounds in an adhesive coating the smaller the risk of allergic skin reactions.

Due to the disadvantages and short-comings of the prior art eiplatory strips there is a need for alternatives and improvements .

In a first aspect according to the present invention is provided an epilatory strip of the kind mentioned in the opening paragraph which has a simple structure.

In a second aspect according to the present invention is provided an epilatory strip of the kind mentioned in the opening paragraph which is inexpensive and easy to use.

In a third aspect according to the present invention is provided an epilatory strip of the kind mentioned in the opening paragraph which is skin-friendly and includes a biocompatible adhesive.

In a fourth aspect according to the present invention is provided an epilatory strip of the kind mentioned in the opening paragraph which is resilient and is able to conform to human body cavities and/or convexities.

In a fifth aspect according to the present invention is provided an epilatory strip of the kind mentioned in the opening paragraph which embeds and traps hair more reliable than known epilatory strips.

In a sixth aspect according to the present invention is provided a method for manufacturing an epilatory strip.

The below test methods are defined in FINAT Technical Handbook 7th edition, 2005. FINAT is the International Federation of Manufacturers and Converters of Self-adhesive and Heat Seals Materials on Paper and Other Substrates. The FINAT test methods are used for testing peel adhesion (FTM 1), resistance to shear (FTM 8) and loop tack measurement (FTM 9) and values of these parameters are stated in the present application for the behavior and performance of epilatory strip test items when tested by the standard FINAT method, not on the users skin, because the skin is not a standard reference surface.

Within the context of the present invention the term "peel adhesion" is used to express the adhesion power between the adhesive and a surface. The peel adhesion test (FTM 1) serves to quantify the permanence of adhesion or peelability of self- adhesive pressure-sensitive materials. "Peel adhesion" is defined as the force required to remove pressure-sensitive coated material applied to a standard test plate under specified conditions from said plate at a specified angle and speed. The test strip is 25 mm wide and has a minimum length of 175 mm. The strip is peeled through an angle of 180° with a jaw separation rate of 300mm per minute with an accuracy of ± 2%. Further test conditions are temperature (T) 23°C ± 2°C and relative humidity (RH) 50% ± 5%. The value of the peel adhesion gives an indication about the force required to pull the strip off an individual's skin.

Within the context of the present invention the term "resistance to shear" refers to the cohesive force between the molecules of the adhesive. Resistance to shear is measured as resistance to shear from a standard surface according to FTM 8, wherein the resistance to shear is defined as the time required for a standard area of 25mm x 25mm of pressure- sensitive coated material to slide from a standard flat surface in a direction parallel to the surface. The resistance to shear test gives an indication of the likely mode of bond failure, i.e. adhesive failure or cohesion failure. The test strips are 25mm wide and have a minimum length of 175mm in the machine direction. Further test conditions are temperature (T) 23°C ± 2°C and relative humidity (RH) 50% ± 5%. The higher resistance to shear, the less residues the adhesive leaves on the skin.

Within the context of the present invention the term "loop tack" refers to the initial grab or tack of the adhesive once it touches a surface, such as the individual's skin, and without applying pressure to the adhesive. Good tack value of a hot-melt pressure-sensitive adhesive is highly important is highly important to ensure that hair can be satisfyingly stripped off the skin.

The "loop" tack value" of a pressure-sensitive material is defined in FTM 9 and is expressed as the force required to separate, at a specified speed of 300 mm per minute in the test machine direction, a test item being a loop made of an adhesive-coated material strip 25 mm wide and 175 mm long and folded so that the adhesive faces outermost. In the FTM 9 test the exposed adhesive is brought into contact with a specified area of a glass standard surface and then subjected to pulling forces perpendicularly away from the standard surface until detachment from said standard surface. Further test conditions are temperature (T) 23°C ± 2°C and relative humidity (RH) 50% ±

R 2o- ·

The term "adhesive coat weight" refers to the amount in g/m ² of dry pressure-sensitive hot-melt adhesive on a standard area of substrate. Numerical coat weight values are obtained from cut samples using the test method defined in ISO 536.

The novel and unique whereby the above and other aspects are achieved according to the present invention consists in that the method comprises

- providing a width of a first laminate consisting of a pressure-sensitive, hot-melt adhesive sandwiched between a support layer and a first release liner, - delaminating the width of first laminate by unwinding the first release liner and exposing an area of pressure- sensitive, hot-melt adhesive, and

- providing a second relase liner to cover at least a portion of exposed area of pressure-sensitive, hot-melt adhesive to provide a width of epilatory strip material.

The term "pressure-sensitive" indicates, that the bonding force is influenced by the amount of pressure, which is used to apply the adhesive to the selected surface. Pressure-sensitive adhesive are designed to form a bond and hold properly at room temperatures. Pressure-sensitive adhesives reduce or lose their tack at cold temperatures and reduce their shear holding ability at high temperatures. The "hot-melt" adhesives used in the present invention are thermoplastics, tacky in hot state, sets fast in few seconds to one minute, are highly cohesive, have long shelf life and can be disposed of without special precautions. Low-viscosity, high-tack, pressure-sensitive, hot- melt adhesives such as styrene-ethylene/ butylene-styrene tri- block copolymer and/or styrene-ethylene/propylene di-block copolymer are preferred.

Due to being sandwiched inside the first laminate the pressure- sensitive, hot-melt adhesive is protected on both sides prior to being incorporated in epilatory strips. The risk that the pressure-sensitive, hot-melt adhesive becomes contaminated is substantially eliminated. No pressure-sensitive, hot-melt adhesive is exposed to the environment for long periods during manufacturing the epilatory strip, and high bonding and tacking properties of the pressure-sensitive, hot-melt adhesive are well-preserved. The above method is simple and fast and uses simple means to make an inexpensive epilatory strip, which is easy to use by a person intending to remove hair from a chosen skin area. The method may also include to apply at least one mask or cover material onto the pressure-sensitive, hot-melt adhesive on at least one edge area of the delaminated first laminate to provide a second laminate presenting an exposed area of pressure-sensitive, hot-melt adhesive for tacking hairs. The mask or cover material expediently serves to prevent the second release liner from bonding to the masked or covered edge area of the delaminated first laminate.

Thus the firm bonding ability of the pressure-sensitive, hot- melt adhesive is expediently utilized to bond said one or more mask or cover materials to at least one edge area of the delaminated first laminate. The user never gets sticky fingers because the user does not need to touch the pressure-sensitive, hot-melt adhesive with his/hers fingers. Preferably, the mask or cover material is permanently bonded to the support layer by means of the pressure-sensitive, hot-melt adhesive, however even though it is less preferred the mask or cover material may be combined with the pressure-sensitive, hot-melt adhesive in a releasable manner to be able to utilise the entire adhesive area for hair removal.

With respect to the first laminate the method can further comprise obtaining the first laminate by transfer coating the pressure-sensitive, hot-melt adhesive onto the support layer from the first release liner by means of pressure lamination, optionally by means of heated pressure lamination rollers, to ensure that the pressure-sensitive, hot-melt adhesive sticks to the support layer with a greater bonding force than to the first release liner. Heat may be applied to soften the adhesive and expedite the transfer to the opposite support layer, as well as the lamination rollers create a bonding force between support layer and pressure-sensitive, hot-melt adhesive that is sufficient to ensure that the pressure-sensitive, hot-melt adhesive remains bonded to the support layer when hairs, entangled and tacked by the pressure-sensitive, hot-melt adhesive, are ripped off.

The first release liner, e.g. a paper or silicon release liner, thus only serves as a temporary carrier of the pressure- sensitive, hot-melt adhesive, and is selected by its property to easily let off an adhesive coating or adhesive deposition. Transfer coating is highly preferred because the position, the layer thickness, and hardness or softness of the pressure- sensitive, hot-melt adhesive, used in the present method, can easily be controlled without using complicated control procedures and special equipment.

Individual epilatory strips or lengths of epilatory strip material can advantageously be divided out of the epilatry strip material by end cutting said width of epilatory strip material, e.g. using a die cutter, a punch tool or a blade cutter. Various sizes of epilatory strips can be made by selecting an appropriate tool. The length of a simple rectangular epilatory strip can e.g. be controlled by adjusting the conveying speed in the production line in relation to end cutting speed. High conveying speed and low cutting speed produce long epilatory strips and vice versa.

In an alternative embodiment the epilatory strip material can be provided with spaced apart rupture lines crosswise the width of said epilatory strip material. Such epilatory strip material end product may advantageously be taken-up in rolls. The rolls may be sized for the user to decollate a length suitable for an intended use. The suitable length may or may not be the length between two subsequent rupture lines or include several rupture lines. The distance between the rupture lines may be selected as appropriate and desired. The distance can be adjusted in the same manner as described above for the length of the individual epilatory strip. In a preferred embodiment the at least one mask or cover material can be two opposing cover ribbons provided along opposing free edges of the delaminated first laminate, preferably the long edges of the production direction, i.e. the conveying direction. Such cover ribbons are easy to apply in a continuous production line and create, in a simple manner, easy accessible grasping flaps of considerable size on two opposing edge surface areas of the epilatory strip.

The at least one mask or cover material can be colored or can present an information. For example, a blue color can be used for epilatory strips especially designed for men, and a red color indicates that the epilatory strip is for women. Any kind of information can be provided on or be integrated in the mask or cover material.

Information can also be provided on the visible surface on any of the second release liner or the support layer. Information can e.g. be directions for use, company logo, or brand name of the epilatory strip product. Information can be printed or embossed .

If the second release liner is a low release liner, it can be removed without tearing the support layer to pieces or pulling the pressure-sensitive, hot-melt adhesive along. Prior to removal, said second release liner also provides structural stability to the epilatory strip. The second release liner may at least partly overlap the at least one mask or cover material so that a peripheral zone or just a part of the mask or cover material are left free for grasping to facilitate easy removal of the second release liner. A free overlapping part of the second release liner can be grasped between two fingers of one hand while taking the masked or covered edge area between two fingers on the other hand to peel the second release liner off the pressure-sensitive, hot-melt adhesive to expose the latter. The release liners for use in the method according to the present invention are preferably silicon paper, siliconized polyethylene (PE) or siliconized polyethylene terephthalate (PET) having weights between 70 - 100 g/m ² , and preferably also being clear or opaque.

The preferred weight of the pressure-sensitive, hot-melt adhesive coating in the first laminate is between 50 - 55 g/m ² . Products having different coating weights, including weights outside the above interval, can also be manufactured using the method according to the present invention. Epilatory strips incorporating high amounts of pressure-sensitive, hot-melt adhesive may be useful on very hairy skin, including hirsutism and male skins. Epilatory strips incorporating lower amounts of pressure-sensitive, hot-melt adhesive coating may suffice for women practicing frequent epilation.

By using the method according to the present invention it is possible to obtain an epilatory strip material meeting a number of valued and beneficial product characteristics that makes the obtained epilatory strip suitable for efficient but still careful and gentle epilation of different hair types from different body parts. Irrespective to the hair having different length, thickness, being rough, thin, curled or smooth, the epilatory strip obtained according to the method of the present invention is very effective in hair removal.

Product characteristics to be fulfilled by the epilatory strips according to the present invention include but are not limited to any of that

- the preferred loop tack of the pressure-sensitive, hot-melt adhesive is 20 ± 4N per 25 mm width of epilatory strip according to FINAT Test Method no. 9 using a stainless steel plate as pressure plate,

- the preferred peel adhesion of the pressure-sensitive, hot- melt adhesive is 16 ± 4N per 25 mm width of epilatory strip according to FINAT Test Method no. 1 using a stainless steel plate as the test plate and a 20 min. test period, and/or - the preferred resistance to shear of the pressure-sensitive, hot-melt adhesive is > 40 min per 25 mm width of epilatory strip according to FINAT Test Method no. 8 using a stainless steel plate as the test plate.

The loop tack of the the pressure-sensitive, hot-melt adhesive is high while being cold, but warming increases initial tackiness of a hot-melt adhesive. Some users may prefer to rub the epilatory strip between the hands prior to application on the skin.

The thickness of the support layer may be between 50 lm - 1 mm. 50 μηι if for example chosen for a polyethylene film support layer, and 1 mm for a polyethylene foam support layer.

The second release liner may consists of two flaps of release liner, optionally overlapping release liner flaps, to increase user-friendliness of second release liner removal.

If the at least one mask or cover material protrudes beyond at least a part of the outer edges of any of the support layer or the second release liner a protrusion or offset between edges of adjacent layers is obtained, which protrusion or offset can be used in tactile location of the second release liner, as well as when removing the second reelase liner from the delaminated first laminate having the mask or cover material on its adhesive edge area.

A protrusion between 1 - 2 mm has turned out to be sufficient for tactile guidance of the user fingers and facilitation of removal of the second release liner.

The invention is also directed to an epilatory strip obtainable by the method described above wherein the adhesive means is a pressure-sensitive hot-melt adhesive provided as a solitary layer that is transfer coated onto the support layer.

The preferred intervals of the coating weight, the loop tack, the peel adhesion, and the resistance to shear of the pressure- sensitive, hot-melt adhesive are as stated above.

Preferred thicknesses of the various applicable support layers are between 50 lm - 1 mm. Particular preferred support layers are selected from the group of support layers including a foam support layer, a plastic film layer or a non-woven layer, where a foam support layer, such as a polyethylene foam support layer, typically is thicker than a plastic film layer, such as a polyethylene film support layer or a polyethylene terephthalate film layer.

The pressure-sensitive, hot-melt adhesive needs to be firmly bonded to the support layer and to stay on the support layer without percolating, bleeding through or otherwise moving from the application side of said support layer to the opposite back side of the support layer, neither during manufacturing nor during storage of the epilatory strip.

Thus it is highly important that the pressure-sensitive, hot- melt adhesive cannot bleed into or onto the support layer, e.g. in hot weather or under other warm conditions. If bleeding, percolation or other kinds of moving of pressure-sensitive, hot-melt adhesive away from a skin-contacting surface of the epilatory strip take place unknown amounts of said pressure- sensitive, hot-melt adhesive would be lost and not available as an epilation layer.

Thus in the present invention support layers being at least substantially nonporous, preferably having zero porosity, are the most preferred. Also, the support layer should be non- perforated . The pressure-sensitive, hot-melt adhesive is free of colophony. Colophony is highly skin irritants, sensitizing and known to induce contact dermatitis. At the beginning of contact the skin becomes red and inflamed, but as the allergic or irritation reaction progresses blisters turns up and the skin becomes very itchy. Therefore colophony is not included in the adhesive coating used in the present epilatory strip.

Instead a hypoallergenic pressure-sensitive, hot-melt adhesive is incorporated. The pressure-sensitive, hot-melt adhesive may however include another tackifying resin to enhance tackiness to hair, still though is the pressure-sensitive, hot-melt adhesive of hypoallergenic nature.

The preferred pressure-sensitive, hot-melt adhesives used in the epilatory strip and the method for producing the epilatory strip according to the present invention is Duro-Tak® 8673 or Duro-Tak® 8532 obtainable from Henkel KgaA, Henkelstrasse 67 D-40191 Dusseldorf, Germany. The Duro-Taks® are very tacky presseure sensitive hot-melt adhesives that have no content of colophony .

The main constituents of the composition of Duro-Tak® 8673 and Duro-Tak® 8532 are indicated in Table 1 below. The composition of Duro-Tak® 8673 and Duro-Tak® 8532 differ only in the percentage of individual constituents.

Table 1

The pressure-sensitive, hot-melt adhesive may expediently be covered by at least one second release liner to be removed prior to application on the skin area from which hairs are to be removed.

The invention will now be described in further details below with reference to the drawing. The drawing shows an exemplary embodiment of a production line and an epilatory strip manufactured using the production line by means of the method according to the present invention. An exemplary epilatory strip is shown in the figures to be rectangular, but other shapes are encompassed by the claims of the present application. Also other thicknesses of layers are contemplated, and the layer thicknesses indicated in the figures are only for illustrative purposes and should not be taken as limiting the scope of the present invention. Emphasize is made that some layers of the epilatory strip may in fact be so thin that their thickness and presence in the epilatory strip only can be visualized by illustrative magnification.

Fig. 1 shows a perspective exploded view of an exemplary embodiment of an epilatory strip, fig. 2 shows the same in bonded state, and fig. 3 shows schematically a production line according to the present invention.

Fig. 1 shows an exploded view of the components for a preferred rectangular embodiment of an epilatory strip 1 according to the present invention. The epilatory strip 1 has a polyethylene foam support layer 2 transfer coated with a layer of pressure- sensitive hot-melt adhesive 3. The pressure-sensitive hot-melt adhesive layer 3 on the opposing long edge areas 4,5 of the polyethylene foam layer 2 is covered with cover ribbons 6,7 of e.g. polyethylene film. The exposed pressure-sensitive hot-melt adhesive 3 delimited between the cover ribbons 6,7, are protected during storage by a detachable release liner 8, e.g. a siliconized polyethylene liner.

Fig. 2 illustrates the epilatory strip 1 in an assembled, bonded state. The detachable liner 8 partly overlaps the cover ribbons 6,7 in their length direction, thereby providing lengthwise free finger flaps 9,10 not adhered to the subjacent cover ribbons 6,7. The free finger flaps 9,10 are easy to get hold of, in that they can just be folded away from the cover ribbons 6,7 in order to remove the detachable release liner 8.

A production line 11 for performing the method according to the present invention is shown in fig. 3. A width of first laminate 12, consisting of the pressure- sensitive hot-melt adhesive 3 sandwiched between a protective first release liner 13, and a support layer 2 is supplied from a first supply roll 15 via conveyer roll 15a, as shown with arrow A. The pressure-sensitive hot-melt adhesive 3 has initially been coated on a width of first release liner 13, e.g. a siliconized polyethylene release liner. Then a width of support layer 2, e.g. a width of polyethylene foam layer 2, is applied on top of pressure-sensitive hot-melt adhesive 3. Subsequently the sandwich of width of first release liner 13, width of pressure-sensitive hot-melt adhesive 3 and the support layer 2 is conveyed through pressure rollers (not shown) to transfer coat the pressure-sensitive hot-melt adhesive 3 onto the width of the support layer 2.

The first laminate 12 is delaminated by means of delamination roll 16 and waste roll 16a that unwinds the first release liner 13, as indicated with arow B, to expose the pressure-sensitive hot-melt adhesive 3 on the width of support layer 2 and produce a delaminated first laminate 17.

Cover ribbons 6,7 delivered from supply rollers 18,19, respectively, as indicated by arrows C and D, are continuously laminated to opposing adhesive edge areas 3,5 of the delaminated first laminate 17 by means of first lamination rollers 20 to provide a second laminate 21 presenting an exposed area 22 of pressure-sensitive hot-melt adhesive 3 between the cover ribbons 6,7.

As indicated by arrow E, the second laminate 21 is conveyed to lamination by second lamination rollers 23, were a width of second release liner 8, e.g. a siliconised polyethylene liner, is supplied from supply roll 24, as indicated by arrow F, is applied on the pressure-sensitive hot-melt adhesive 3 to produce a width of epilatory strip material 25 that cannot stick unintentionally to other surfaces. The width of second release liner 8 also serves for protecting the pressure- sensitive hot-melt adhesive 3 from sticking to dirt and from desiccation during storage.

The width of epilatory strip material 25 is transported further through the production line 11 by means of conveyer rolls 26, as indicated by the arrow G, to be cut into epilatory strips 1, by means of e.g. a cutting blade. The epilatory strips 1 may then be wrapped individually or in sets.

The epilatory strip 1 according to the present invention can be used on a plurality of different body areas and body parts including but not limited to toes, feet, lower leg, upper leg, groin, bikini line, anal area, belly area, back, shoulder, breast, finger, hand, upper arm, under arm, arm pit, chin, neck, auricle, ear channel, upper lip, cheeks, nose bridge, eyebrows, and forehead. Also, the epilatory strip 1 can be made in various sizes and shapes. Thus, although the above embodiment is shown with cover ribbons other kinds of masks can also be used. E.g. a width of mask material having cut out sections corresponding to the area of pressure-sensitive material to be exposed for use in hair removal can be applied to the delaminated first laminate. The protected edge area then may have a different configuration and the final epilatory strip product also be given different shape than squared, e.g. oval or circular, which shape can be obtained by die cutting.

The final end product epilatory strip may also be provided with cut out sections that leaves a pattern of hair back after ripping off the epilatory strip.

Variations and combinations of the embodiments discussed above are intended within the scope of the present invention.