EP1557206A1

EP1557206A1 - Decoration of a multi-layered device, especially a (winter) sports apparatus

Info

Publication number: EP1557206A1
Application number: EP04001355A
Authority: EP
Inventors: Zef Breukers
Original assignee: Gurit Ittigen AG
Current assignee: SITRA AG
Priority date: 2004-01-22
Filing date: 2004-01-22
Publication date: 2005-07-27

Abstract

The claimed process of applying a decoration to a device, especially a winter sports apparatus, wherein the decoration comprises at least two layers and wherein each layer comprises at least one color agent, is characterized in that it comprises the steps of: (-) providing a basic layer carrying the decoration, wherein the decoration is configured suchlike to withstand heated press cycles of temperatures of greater than 120°C, preferably of greater than 140°C, most preferably greater than 160°C; and pressures of more than 2 bar, preferably more than 10 bar, most preferably more than 15 bar; (-) attaching the decorated basic layer to the device; and (-) applying an outer protective sheet and/or a protective-lacquer or -varnish to the basic layer, facing outwards of the device, wherein the protective sheet is at least partially transparent in the area of the decoration. The invention further allows for easy and cost-efficient production and supply of semi-finished products.

Description

The invention is related to a process of applying a decoration to an especially area-measured device, especially a (winter) sports apparatus, possessing a multi-layered structure, devices and semi-finished sheet products obtainable by said process and the use of crosslinkable, preferably irradiation curable color agents within said purpose.
A winter sports apparatus such as e.g. skis and snowboards possess a core structure, commonly made from wood or synthetic material such as urethane foam. A ski further possesses a reinforcing, upper layer ("Obergurt"), made from synthetic fibers such as e.g. glass, carbon or aramids, typically connected to the core structure by e.g. an epoxy resin. As next-outer layer, a plastic protective layer is currently always provided, usually referred to as top surface. On the backside of the transparent protective layer, decorations such as text, images or the like are applied. The protective layer is applied in order to provide abrasion- and impact resistance, and needs to withstand dynamic load and temperature conditions which are common in outdoor use. Typically, additional lacquers or varnishes are applied for increased scratch and UV resistance and control of glossy or matt surface appearance.
For the decoration of especially area-measured devices such as the above-mentioned winter sports apparatusses, several techniques are currently in use:
Silk screen printing is a discontinuous process, wherein each surface is decorated with individual, investment-intensive equipment, i.e. individual screens for each decoration. Each color needed for the decoration is to be applied and dried separately, rendering the process highly time-consuming and elaborative. Moreover, expensive inks are required if the device is to be used under high dynamic loads, as is the case e.g. for winter sports apparatuses, in order to assure improved resistance to peeling, shearing and shock impact in the device.
The dye sublimation technology is characterized in that especially multi-colored patterns are printed on a carrier, e.g. paper and are subsequently transferred to the protective top surface plastic sheet, e.g. of a ski, discontinuously in a thermal press cycle or continuously in a roll calender. As this process affords application of high temperatures of up to 190°C, expensive top surface materials such as PAll or PA 12 need to be used in order to resist these temperatures. Moreover, this technique is prone to a relatively high transfer failure rate. Another disadvantage of dye sublimation is that it is not a WYSIWYG technique, i.e. transferred colors may appear different as initially expected.
From the Austrian patent AT 406 340 a process for the decoration of skis is known, making use of known digital printing processes such as digital ink jet printing or digital plotting to the backside of the protective sheet. One disadvantage of the proposed process is the application of the decoration to the inwards directed side of the protective layer, rendering the process highly inflexible. The typical thickness of such a protective layer of a ski is mostly in the range of about 600µm, rendering the protective layer relatively stiff, thus hampering easy handling and storing of a semi-finished product. Moreover, once the decoration is applied to a specific, mostly pre-formed protective layer, this protective layer is only usable for this one, specific geometry of the final device. Moreover, digital ink jet printing or plotting is a rather slow process, additionally commonly resulting in horizontal lines within the image, thus hampering the aesthetic appearance of the decoration.
Most digital printing processes are currently using the YMCK (yellow, magenta, cyan, black), four-layer technology. A major disadvantage of these processes is, that such multi-layered toner laminates are prone to delamination under dynamic load, e.g. shear load, especially if applied to e.g. skis. Moreover, the peel strength of such laminates is very low. Although with such conventional techniques, the toner layers are thermally fused, delamination at the interface of the layers can not be avoided. Additionally, the manufacture of a winter sports apparatus involves several lamination steps of different layers, typically comprising heated press cycles of heating in the range of e.g. up to 90-140°C or even higher, typically for about 5 to 20 minutes at pressures of about 2 to 15 bars; conventional thermoplastic toners would melt and flow under these conditions, thus blurring of the decoration would occurs. Thus, conventional thermoplastic toners with glass transition temperatures in the range of about 50°C to 80°C and melting temperatures below 120°C are not preferably suitable for such processes.
It is thus an object of the present invention to overcome the shortcomings of the prior art, especially to provide a process for the decoration of a device with a multi-layered structure, especially a winter sport apparatus, which is cost-saving, easily to implement, which allows for an efficient work-flow in the production of the device and which fulfills the needs of a maximum of delamination-resistance and high resolution of the decoration.
These objects are met by a process of applying a decoration to an especially area-measured device, a semi-finished product for manufacture thereof, a device possessing such decoration and the use of crosslinkable, especially irradiation-curable color agents for the decoration of such device possessing a multi-layered structure according to the independent claims.
These objects are met inter alia by a process of applying a decoration to a device, preferably a sports apparatus, most preferably a winter sports apparatus. The decoration such as a text, logo, image or the like comprises at least two layers, each layer comprising at least one color agent. The process is characterized in that it comprises the steps of:

providing a basic layer carrying the decoration, wherein the decoration is configured suchlike to withstand heated press cycles of:
- temperatures of greater than 120°C, preferably of greater than 140°C, most preferably greater than 160°C; and
- pressures of more than 2 bar, preferably more than 10 bar, most preferably more than 15 bar;
attaching the decorated basic layer to the device; and
applying an outer protective sheet and/or a protective-lacquer or -varnish to the basic layer, facing outwards of the device, wherein the protective sheet is at least partially transparent in the area of the decoration.

According to the invention, the glass transition temperature of the decoration is preferably chosen suchlike to withstand the above-mentioned parameters of temperature and pressure, especially at least for times of about 5 to 20 minutes, i.e. to avoid especially blurring of the decoration, visible by the unaided eye. Moreover, delamination at the interface of neighboring layers comprising the color agent(s) is to be avoided under typically occurring dynamic loads for e.g. skis or snowboards in use.
Upon applying the decoration to a basic layer which is intended to form an inner part of the assembled device, a more flexible material can be chosen for the basic layer in contrast to the prior art, thus facilitating the application of the decoration. Especially, if a mutually transparent basic layer is chosen, the decoration may be applied on only one single or even both area-measured sides thereof. The decoration may furthermore be oriented suchlike within the finished device to face either outwards or inwards, when a transparent basic layer is chosen. According to the prior art, the decoration was applied directly onto the inwards directed face of an outer, transparent protective sheet, which is relatively thick and stiff, whereby an efficient work-flow (i.e. separate production, supply and storage of semi-finished products, e.g. decorations) in the production of the device was hampered.
It is especially preferred, that the process according to the invention of applying a decoration to a device, especially a winter sports apparatus possessing a multi-layered surface, involves the steps of:

applying at least two layers to a basic layer, wherein neighboring layers are crosslinkable with each other and wherein each layer comprises at least one color agent;
crosslinking the at least two layers of color agents (2A,2B,2C,2D) with each other by appliance of an outer influence.

By using crosslinkable layers comprising color agents, the problem of delamination especially within the decoration under dynamic load, a major drawback of the prior art, is overcome: By crosslinking neighboring layers of color agents with each other and within themselves, these layers of color agents are thus bound into one framework, whereby delamination at the interface of different color layers can be efficiently prohibited. If appropriate materials are chosen, crosslinking may also preferably involve neighboring layers adjacent to the color agents. Moreover, irradiation-cured color agents such as e.g. toners curing under ultra-violet irradiation will no longer become liquid and cannot subsequently flow during further manufacturing in e.g. presses under high temperatures, such as commonly applied in the production of a winter sports apparatus such as e.g. ski or snowboard. The crosslinkable component(s) within the layers of color agent(s), especially of such toners are (a) in case of thermally crosslinkable formulations e.g. fluorosilicic resins, poysiloxanes, silicas, acrylics, polyurethanes or the like, and (b) in case of irradiation-crosslinkable formulations e.g. pentaerythritol triacrylate (PETA), trimethylolpropane triacrylate (TMPTA), N-vinylpyrrolidone (VP), N-vinylcaprolactam (VC), triallyl isocyanurate (TAIC), trimethallyl isocyanurate (TMAIC) or the like. If electron beam irradiation is chosen, preferred crosslinkable formulations contain suitable amounts of e.g. polyethylene in all its forms and their blends (e.g. LDPE, LLPE, MDPE, HDPE, etc.), ethylene copolymers (e.g. EVA, EPDM, EEA, EBA, EMA, CSM, etc.), polyvinyl chloride (PVC), polyurethane (PU), polybutylene terephtalate (PBT) or the like.
As used herein, a winter sports apparatus may be any kind of device intended for use on snow and/or ice, e.g. skis, snowboards, etc.; according to the invention, the decoration may be applied either to the top surface or the running surface of the device. The invention is especially useful for devices that are exposed to dynamic loads such as shear load. It is obvious to the person of routine skill in the art to implement the invention also to other sports and/or outdoor devices such as e.g. skate-boards, surf-boards, etc..
As used herein, the term color agent comprises any kind of substances known in the art for coloration and/or decoration of substrates. Preferred color agents are inks and dry or solvent-based toners, such as those routinely used by the person of routine skill in the art of especially digital printing. Most preferably, the color agents are solvent-based, especially preferred dry toners of the YMCK (yellow, magenta, cyan, black; sometimes comprising a fifth, specially pre-composed color agent) or RGB (red, green, black) system. Such dry toners are typically based on polyols and/or polyesters, filled with pigments and processing additives such as e.g. rheology modifiers, etc..
As used herein, the term crosslinking is used in the sense of chemical crosslinking. Upon crosslinking of and within a layer of a first color agent, a chemically compatible, adjacent layer of a second color agent is thus chemically crosslinked within itself, too, but also to the first layer. Crosslinking may thereby occur via an ionic or, especially preferred, a radical pathway. For crosslinking of the color agents, especially any kind of outer influence, especially an irradiation source suitable for initiation of an ionic and/or radical pathway may be used. Preferably, curing and/or crosslinking is effected by means of microwave or radio frequency, infra-red, electron beam or, especially preferred, ultra-violet (UV). Most preferably, curing and/or crosslinking is based on the presence of activated carbon-carbon double bonds such as acrylates, methacrylates, allyl, styrenyl or vinyl. Although crosslinking by means of irradiation is preferred, any other suitable process known in the art of polymerization may be applied for crosslinking of the different color agent layers. Thus, any kind of initiation may be applied such as e.g. moisture-curing and/or -crosslinking systems and/or heat-curing and/or -crosslinking systems. Moreover, chemically blocked reagents (such as deactivated isocyantes or the like; deactivation of isocyanates with e.g. 1° or 2° aliphatic amines, di- or polyamines, hydrazine derivatives, amidines or guanides is known to the person of routine skill in the art) or micro-encapsulated reagents (both to liberate by either moisture, heat, irradiation or the like) may be used.
In a preferred embodiment of the present invention, the at least two layers of irradiation curable color agents are applied by means of a digital printing process, preferably a high resolution digital press. Preferred high resolution digital presses are commercially available, e.g. Xeikon DCP 320/500 simplex or duplex machines (Xeikon International, Lier, Belgium); HP Indigo w3200 digital press (HP Indigo, Maastricht, The Netherlands); Agfa Chromapress (Agfa-Gevaert, Mortsel, Belgium); Xerox Docu-color 70 and 100 (Xerox Corp., Stamford, CT, USA), IBM Infocolor 3170 and IBM Infoprint Color 130 (IBM Corp., Armonk, NY, USA); or the like. Such high resolution digital presses are especially preferred because of their high quality of reproduction (600 dpi or even higher) and their capacity. Preferably, the layer thickness of each color agent is within the range of about 5 to 8 µm. However, also conventional computer-based ink-jet printing, laser printing, etc. is applicable within the concept of the present invention. Due to the ease of computer-based image-processing, disadvantages of e.g. silk screen printing and offset printing, where further technical equipment for each separate image or decoration is necessary, are overcome.
According to an especially preferred embodiment, the basic layer to be attached to the core construction of the device is made from plastic, especially comprising polyethylene terephtalate (PET). Preferably, the basic layer is pre-treated for enhancement of the bonding of the color agents. Suchlike coated PET films are commercially available e.g. from Hanita Coatings (Kibbutz Hanita, Israel) under the tradename Durakote, e.g. article K07512; from Folex AG (Seewen-Schwyz, Switzerland), under the tradename Digiprint XE Films (e.g. article 0681.5.736); and from Hifi Film (Stevenage, Hertfordshire, United Kingdom) under the tradename Digital Print Polyester Films. Most preferably, the basic layer is white or transparent in order to aid the appearance of the decoration; especially white basic layers are preferred in order to 'hide' undesired patterns, roughnesses and discolorations of underlying layers.
For both the connection of the protecting sheet to the especially multi-layered structure and the connection of the especially multi-layered surface to a core construction of the device, suitable adhesives known to the person of routine skill in the art are preferably used. These adhesives need to be adapted to the materials to be connected and may be applied as bulk material or film. As an alternative, e.g. surface flame treatment with a Pyrosil® additive (Sura Instruments, Jena, Germany) may be used for attachment of the decorated basic layer to the core construction.
According to another preferred embodiment, the decoration is applied to a basic layer, preferably mediated by a primer layer, and the decoration is based on developing of a multi-layered photographic emulsion, preferably a light-sensitive color-photographic emulsion. Such multi-layered photographic emulsions are known in the art and are especially useful for production processes of devices that afford application of high temperatures, when they are mouldable. Such mouldable photographic materials are e.g. known from WO 98/35269, herewith incorporated by reference. It is especially preferred that the multiple layers of the photographic layer are cured and crosslinked by means of an outer influence, e.g. irradiation.
The invention moreover relates to a semi-finished sheet product for manufacturing of a device, preferably a sports apparatus, most preferably a winter sports apparatus, comprising a preferably white basic layer carrying a decoration, wherein the decoration comprises at least two layers of color agents with an interface in between these at least two layers of color agents, and wherein the composition of the decoration is configured suchlike to withstand heated press cycles of

temperatures of greater than 120°C, preferably of greater than 140°C, most preferably greater than 160°C; and
pressures of more than 2 bar, preferably more than 10 bar, most preferably more than 15 bar.

Such a semi-finished product is resistant to blurring of the decoration under normal heat press cycles typically applied in e.g. ski and snowboard manufacturing. Morevover, delamination at the interface in between the two layers of color agents is avoided, especially under dynamic shear loads commonly occurring in use of e.g. skis or snowboards.
The semi-finished product preferably comprises a basic layer carrying a decoration, wherein the decoration comprises at least two layers of color agents, and wherein the color agents are crosslinked with each other. Thuslike, and especially making use of the process according to the invention, personalization of surface decorations is possible without complicated logistics: a laminate comprising the preferably already cured and crosslinked layers of color agents on a basic layer can be easily provided, shipped and stored e.g. on rolls, thus facilitating the overall course of production and making it more flexible.
A semi-finished product according to the invention may be supplied to the manufacturer of the final device e.g. pre-assembled (e.g. laminated) to the protective top surface layer. After commonly used heat press cycles of the production line of e.g. ski and snowboard manufacturing, additional protective-lacquers or - varnishes may be applied.
According to another embodiment of supply of a semi-finished product according to the invention, the basic layer carrying the decoration may be preliminarily coated with a release film, which is suitable to withstand common transport-, storing- and preferably also heat press cycle conditions. The release film is taken off preferably only after the heat press cycles. Afterwards, a conventional protective layer or, especially preferred, an impact- and scratch resistant, especially UV-resistant lacquer or varnish, may be applied to the device. Such lacquers or varnishes are typically e.g. based on two-component urethane resins applied in a curtain coating process.
A device, especially a winter sports apparatus, possessing a multi-layered surface is preferably made by a process outlined above and/or by using a semi-finished product outlined above, especially a laminated sheet product, comprising layers of color agents on a basic layer, wherein the layers of color agents are crosslinked with each other by means of an outer influence such as irradiation, heat or moisture, especially UV-irradiation.
The invention will now be described by means of figures and examples in more detail, without the invention being limited to these preferred embodiments.

Fig. 1:: side-view of a multi-layered device according to the invention.

As shown schematically in Figure 1, a device 1, especially a winter sports apparatus, possessing a multi-layered surface is built up on a core construction 5. In case of the device 1 being a ski, snowboard or the like, the core construction 5 is mostly made from epoxy resin such as 100 parts by weight of Araldite 136N with e.g. 35 parts by weight of Araldite HY 991 (Vantico, Huntsman, Eversberg, Belgium). The device 1 comprises a decoration made up from at least two layers of irradiation curable color agents 2A,2B,2C,2D applied to a basic layer 3, preferably by means of a digital printing process. Irradiation, here UV-curing and crosslinkable color agents 2A,2B,2C,2D were prepared by mixing and homogenizing commercially available dry toners with equally grain-sized, crosslinkable components such as triallyl isocyanurate (TAIC; Sartomer, Exton, PA, USA). The necessary amount of the crosslinkable component to be added to the color agent in order to achieve a sufficient increase of the glass transition temperature Tg of the decoration is easily to determine by routine experiments of the person of routine skill in the art. The basic layer 3 is a Durakote K0712 film (Hanita Coatings, Hanita Kibbutz, Israel). With devices 1 that need to resist dynamic loads, especially shear loads, a major drawback of the prior art is that multi-layered decorations such as images images are prone to delamination at the interface of separate color layers. According to the invention, irradiation curable and crosslinkable color agents 2A,2B,2C,2D are used for the decoration. Upon subjecting the suchlike prepared decoration to an irradiation source such as UV light, the different color agents are forming a chemically crosslinked network, thus overcoming the problem of occasional delamination at the interface of different color layers. A semi-finished laminated sheet product comprising the basic layer 3 and the color agents 2A,2B,2C,2D may be produced, stored and supplied (e.g. on rolls) separately from the production of device 1, thus facilitating logistic needs significantly. Such a semi-finished laminated sheet is to be connected to the protecting sheet 4, e.g. by means of a suitable adhesive 6A, e.g. a polyurethane-based, thermoplastic adhesive film such as Puro L (Collano Xiro AG, Schweiz). As a protecting sheet 4, Duraclear (IMS Kunststoff AG, Worb, Switzerland) was chosen with a thickness in the range of about 300µm to about 1mm, preferably in the range of about 600µm. Moreover, an appropriate adhesive 6B may also be chosen for the connection of the basic layer 3 to the core construction 5; in this embodiment, Puro L (Collano Xiro AG, Switzerland) was chosen, too. The choice of suitable adhesives for any mentioned connection, however, is within the routine knowledge of the person skilled in the art; especially, hot melt adhesives, preferably based on co-polyester resins, such as XAF 37.204 and XAF 37.304 (Collano Xiro AG, Switzerland) may also be used. Whether additional layers or not need to be integrated in addition to the adhesives 6A,6B in order to achieve a suffiently delamination-resistent laminate, can be easily investigated by routine experiments. However, especially for the connection of the basic layer 3 to the core construction 5, a flame treatment of the PET basic layer with Pyrosil® flame additives as provided by Sura Instruments (Jena, Germany) may be used in order to improve the bonding strength of the adhesive system onto the PET film.

Claims

Semi-finished sheet product for manufacturing of a device (1), preferably a sports apparatus, most preferably a winter sports apparatus, comprising a preferably white basic layer carrying a decoration, with the decoration comprising at least two layers (2A,2B,2C,2D) with an interface in between these at least two layers (2A,2B,2C,2D) and with each layer comprising at least one color agent, wherein the composition of the decoration is configured suchlike to withstand heated press cycles of

temperatures of greater than 120°C, preferably of greater than 140°C, most preferably greater than 160°C; and

pressures of more than 2 bar, preferably more than 10 bar, most preferably more than 15 bar,

without blurring of the decoration and/or delamination at the interface in between the at least two layers (2A,2B,2C,2D) to occur.
Semi-finished product according to claim 1, wherein the glass transition temperature of the composition of the decoration is higher than about 120°C, preferably higher than 130°C, most preferably higher than 140°C.
Semi-finished sheet product, especially according to one of claims 1 to 2, carrying a decoration, wherein the decoration comprises at least two layers (2A,2B,2C,2D), with each layer comprising at least one color agent, and wherein these layers (2A,2B,2C,2D) are crosslinked with each other.
Semi-finished product according to one of claims 1 to 3, obtainable by a process involving the steps of:

applying at least two layers of crosslinkable color agents (2A,2B,2C,2D) to a basic layer (3);

crosslinking the at least two layers of color agents (2A,2B,2C,2D) with each other by appliance of an outer influence.
Semi-finished product according to claim 4, wherein the at least two color agents (2A,2B,2C,2D) are crosslinked with each other by a process involving heat, moisture or irradiation such as UV-, microwave-, infra-red- or electron-beam-irradiation.
Semi-finished product according to one of claims 3 to 5, wherein the at least two layers of color agents on the basic layer are obtainable by means of a digital printing process, preferably a high resolution digital press.
Semi-finished product according to one of claims 1 to 6, wherein the basic layer (3) is pre-treated for enhancement of the bonding of the color agents (2A,2B,2C,2D).
Semi-finished product according to one of claims 1 to 7, wherein the basic layer (3) is made from plastic, especially comprising polyethylene terephtalate.
Semi-finished product according to one of claims 1 to 8, wherein the protective sheet (4) is applied to the basic layer (3) by means of an adhesive and/or the basic layer (3) carrying the decoration, is fixed to a core construction (5) of the device (1) by means of an adhesive.
Semi-finished product according to one of claims 1 to 9, wherein the decoration is applied to a basic layer (3), preferably mediated by a primer layer, and wherein the decoration is based on developing of a multi-layered photographic emulsion, preferably a light-sensitive color-photographic emulsion.
Process of applying a decoration to a device (1), preferably a sports apparatus, most preferably a winter sports apparatus, wherein the decoration comprises at least two layers (2A,2B,2C,2D) and each layer comprising at least one color agent, comprising the steps of:

providing an especially white basic layer carrying the decoration, preferably a semi-finished product according to one of claims 1 to 10, wherein the decoration is configured suchlike to withstand heated press cycles of:

temperatures of greater than 120°C, preferably of greater than 140°C, most preferably greater than 160°C; and

pressures of more than 2 bar, preferably more than 10 bar, most preferably more than 15 bar;

attaching the decorated basic layer to the device; and

applying an outer protective sheet and/or a protective-lacquer or -varnish to the basic layer, facing outwards of the device (1), wherein the protective sheet and/or the protective-lacquer or -varnish is at least partially transparent in the area of the decoration.
Device (1), especially a winter sports apparatus possessing a multi-layered structure, comprising a decoration on a basic layer, the decoration comprising at least two layers (2A,2B,2C,2D) comprising each at least one color agent, with an interface in between these at least two layers (2A,2B,2C,2D), and wherein the at least two layers (2A,2B,2C,2D) are crosslinked with each other at said interface.
Device (1) according to claim 12, wherein the basic layer (3) carries a primer for enhancement of the bonding of the color agents (2A,2B,2C,2D).
Device (1) according to one of claims 12 or 13, wherein the basic layer (3) is made from plastic, especially comprising polyethylene terephtalate (PET).
Device (1) according to one of claims 12 to 14, wherein the decoration is applied to a basic layer (3), preferably mediated by a primer layer, and wherein the decoration is based on a developed, multi-layered photographic emulsion, preferably a light-sensitive color-photographic emulsion.
Use of color agents (2A,2B,2C,2D) comprising a crosslinkable additive, preferably applied in at least two layers, for the decoration of a device (1) possessing a multi-layered structure, especially a winter sports apparatus.
Use of a multi-layered, especially curable and/or crosslinkable photographic emulsion, preferably a light-sensitive color-photographic emulsion, for the decoration of a winter sports apparatus.