Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C59/00—Surface shaping of articles, e.g. embossing; Apparatus therefor
  • B29C59/02—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing
  • B29C59/026—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing of layered or coated substantially flat surfaces
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C59/00—Surface shaping of articles, e.g. embossing; Apparatus therefor
  • B29C59/02—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing
  • B29C59/04—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing using rollers or endless belts
  • B29C59/046—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing using rollers or endless belts for layered or coated substantially flat surfaces
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/40—Adhesives in the form of films or foils characterised by release liners
  • C09J7/403—Adhesives in the form of films or foils characterised by release liners characterised by the structure of the release feature
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
  • B29C35/02—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould
  • B29C35/08—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation
  • B29C35/0805—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation using electromagnetic radiation
  • B29C2035/0827—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould by wave energy or particle radiation using electromagnetic radiation using UV radiation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
  • B29L2009/00—Layered products
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2423/00—Presence of polyolefin
  • C09J2423/006—Presence of polyolefin in the substrate
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2427/00—Presence of halogenated polymer
  • C09J2427/006—Presence of halogenated polymer in the substrate
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2467/00—Presence of polyester
  • C09J2467/006—Presence of polyester in the substrate
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2483/00—Presence of polysiloxane
  • C09J2483/005—Presence of polysiloxane in the release coating
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/14—Layer or component removable to expose adhesive
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/14—Layer or component removable to expose adhesive
  • Y10T428/1452—Polymer derived only from ethylenically unsaturated monomer
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/14—Layer or component removable to expose adhesive
  • Y10T428/1452—Polymer derived only from ethylenically unsaturated monomer
  • Y10T428/1457—Silicon
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/14—Layer or component removable to expose adhesive
  • Y10T428/1486—Ornamental, decorative, pattern, or indicia
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
  • Y10T428/24479—Structurally defined web or sheet [e.g., overall dimension, etc.] including variation in thickness
  • Y10T428/24612—Composite web or sheet
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/28—Web or sheet containing structurally defined element or component and having an adhesive outermost layer
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/28—Web or sheet containing structurally defined element or component and having an adhesive outermost layer
  • Y10T428/2848—Three or more layers

Definitions

• the present invention relates to a method of forming a three- dimensional microstructure on a flat surface of a support, to the uses of said method, as well as to the products and in particular to the self-adhesive films comprising such a three-dimensionally microstructured surface. It is known to provide films made of adhesive which are sensitive to pressure, and whose topography is conferred by contacting the three dimensionally microstructured surface of a peelable protecting coating as support, which is essentially the inverse of the three-dimensional microstructure with which the surface of adhesive is contacted, and methods for the formation of such self-adhesive films.
• the three-dimensional structures are obtained either by mechanically embossing the support comprising a flat film made of silicone or by coating silicone on a support which already presents a microstructured surface, in that case matching the topography of the support.
• the methods for the formation of such self-adhesive films generally turn out to be rather satisfactory, they have limited application, as they can only be produced on expensive polyethylene or polypropylene supports.
• the formation of microstructures in the silicone is carried out by hot embossing at speeds on the order of 0.9 m/min of the engraved cylinder which is used for this purpose, which considerably slows the productivity and raises the production costs of the finished products.
• EP 149135 discloses pressure sensitive adhesive structures having islands of adhesive
• EP 180598 discloses removable label stock having adhesive segments
• EP 861307 discloses an adhesive sheet having a plurality of adhesive pegs and also it should be mentioned patent application WO 97/43319 relating to top coat film useable in preparing a stable polymeric laminated data carrying device, said topcoat film comprising a topcoat layer being formed from a composition comprising a polymerizable composition and a polymeric binder, which is substantially plasticizer free, and wherein the ratio by weight of polymerizable composition to polymeric binder is between 0.75:1 and 1.50:1 inclusive.
• US patent 4,986,496 relates to an article capable of reducing the resistance to drag of a fluid flowing thereover, which comprises a thermoset polymeric sheet formed in situ from the reaction product of an isocyanate with a polyol, said sheet having a surface contacting said fluid comprising a series of parallel peaks separated from one another by a series of parallel valleys.
• Patent application EP 0 382 420 A2 provides a composite plastic article comprising a tough, flexible substrate, one face of which bears a microstructure of discontinuities, which microstructure has a depth of 0.025 mm to about 0.5 mm, and comprises a cured oligomeric resin having hard segments and soft segments, the cured resin being substantially confined to the microstructure portion of the composite.
• One of the purposes of the present invention consequently, consists in overcoming the above-mentioned drawbacks and in providing a method of forming a three-dimensional microstructure on a flat surface of a support which wholly differs from the known processes consisting in deforming a previous plane surface, presiliconized or not to get the desired final microstructured surface.
• the above- mentioned method of making a three-dimensional microstructure comprises the application of a first flat and uniform layer of silicone on said surface of support and the application on the first layer of silicone of a second three dimensionally microstructured layer of silicone, said first layer and second layer of silicone became integrally connected to thus form a common three- dimensional microstructure ensuring anti-adhesive properties distributed regularly on the surface of the support, so that any flexible surface of substrate, in particular a surface of adhesive deposited on said layers of silicone will be microstructured by inverse replication of the three-dimensional microstructure formed by the two layers of silicone, said layers of silicone being fixed by hardening by heating or by exposure to an ultraviolet or electronic radiation, or a combination thereof.
• Another purpose of the present invention consists in providing a method for three-dimensional microstructuring of a surface made of a flexible substrate, in particular a surface of adhesive, which can be produced on any type of substrate, such as papers, plastic films or others, and which allows one to work at very high speed, thus increasing the productivity considerably compared to the known prior methods.
• the above- mentioned three-dimensional microstructuring method comprises the application of a first layer of silicone, which is substantially flat and uniform, on a surface of a support, the application on the first layer of silicone of a second three dimensionally microstructured layer of silicone, where said first and second layers of silicone become integrally connected thus forming a common three-dimensional microstructure ensuring anti-adhesive properties which are distributed evenly over the surface of the support, and the deposition of the flexible surface of substrate, in particular of the surface of adhesive, on the above-mentioned layers of silicone in such a manner that said surface made of flexible substrate, in particular of adhesive, is microstructured by inverse replication of the common three-dimensional microstructure formed by the first layer of silicone and the second layer of silicone, where said layers of silicone are fixed by hardening by heating or by exposure to an ultraviolet or electronic radiation, or a combination thereof.
• the first layer of silicone comprises at least one functionalized polyorganosiloxane with groups
• crosslinking agent as crosslinking agent, and at least one functionalized polyorganosiloxane which can react with the crosslinking agent, or it comprises a functionalized polyorganosiloxanes with groups
• crosslinking agent as crosslinking agent, and at least one functionalized polyorganosiloxane with groups
• the above- mentioned second layer of silicone comprises at least a polyorganosiloxane and, advantageously, a polydimethylsiloxane with acrylate and/or epoxy function, and optionally an activation catalyst.
• the second, layer of silicone comprises a polydimethylsiloxane with acrylate function and a catalyst of the ketone type, advantageously of the benzophenone type, or it comprises a polydimethylsiloxane with epoxy function and a catalyst of the iodonium salt type, and it is hardened by exposure to ultraviolet radiation.
• the second layer of silicone comprises no activation catalyst and it is hardened by exposure to electronic radiation.
• the invention also concerns the three dimensionally microstructured films, and the self-adhesive films which comprise a surface such as one which has been three dimensionally microstructured by the above-mentioned method, notably one comprising motifs which can be used for decorative, publicity or other purposes, notably on the surface opposite the adhesive surface of the self-adhesive films.
• a support such as a flexible support like paper or a plastic film
• a first layer of silicone substantially flat and uniform on said surface of support and one applies on the first layer of silicone a second layer of silicone which has been three dimensionally structured, in such a manner that these layers of silicone become integrally connected to thus form a common three-dimensional microstructure ensuring anti-adhesive properties on the surface of the support.
• any flexible surface of substrate, in particular any surface of adhesive, deposited on both the integrally connected layers of silicone will be microstructured by inverse replication of the three- dimensional microstructure formed by the latter.
• a continuous first layer of silicone which is substantially flat and uniform on a surface of a support, such as one made of paper, which may, for example, be calendered or sized, or a plastic film, such as one made of polyethylene, polyester, polypropylene, polyvinyl chloride, polyamide or a similar material, and one applies to the first layer of silicone a second layer of silicone which has been three dimensionally structured, in such a manner as further described below that these layers of silicone become integrally connected to thus form a common three- dimensional microstructure ensuring anti-adhesive properties which are distributed evenly on the surface of the support.
• microstructured by inverse replication refers to the fact that the topography obtained on the surface of the flexible substrate, in particular of the adhesive, is the inverse motif of the surface topography formed by the combination of the first layer and the second layer of silicone, whose three dimensions in space are substantially similar or similar to the latter.
• substrate denotes any product which will be microstructured by inverse replication of the microstructure formed by the combination of the first layer of silicone and the second layer of silicone and the term “support” will denote any product to which the first layer of silicone or layer of silicone which is substantially flat and uniform is applied.
• the first substantially flat and uniform layer of silicone is formed from a composition of silicone which is based on one or more functionalized polyorganosiloxanes (POS) with groups as crosslinking agent, and from one or more functionalized polyorganosiloxanes (base resin) which can react with the crosslinking agent by polycondensation in the presence of a solvent, and preferably of a tin based activation catalyst, except in the case of hardening of the layer by exposure to electronic radiation.
• POS functionalized polyorganosiloxanes
• base resin which can react with the crosslinking agent by polycondensation in the presence of a solvent, and preferably of a tin based activation catalyst, except in the case of hardening of the layer by exposure to electronic radiation.
• base resin one or more functionalized polyorganosiloxanes with groups
• composition of silicone which can react with a crosslinking agent by polyaddition with or without solvent, where R comprises at least one ethylenic unsaturation, preferably a vinylic unsaturation, in the presence of platinum and/or rhodium catalyst.
• This composition of silicone moreover can comprise additives such as those which are conventionally used in this type of application, namely an adhesion modulator, for example, based on a silicone resin comprising siloxyl units, reaction accelerators and inhibitors, pigments, surfactants, fillers or similar substances.
• the composition of silicone mentioned above can be liquid and diluted in a solvent such as hexane or toluene and, for reasons pertaining to hygiene and safety, it can be in the form of an aqueous dispersion/emulsion.
• a solvent such as hexane or toluene
• the expression "flat and uniform” denotes the fact that the layer of silicone comprises no surface asperities or roughness which could tarnish the flat configuration of its surface, i.e. the silicone layer will tend to wet out and be continuous over a support surface without having any disruptions that would interfere with the ultimately desired release characteristics or 3 dimensional topography of the siliconized support following the application of the second layer.
• This composition of silicone constituting the first layer which is either made of a solvent base or without solvent, is hardened by crosslinking with heating in a reaction of polyaddition or polycondensation, for example, by being subjected to temperatures of 70-220°C, advantageously 100-180°C, or under exposure to radiation energy, such as ultraviolet or electronic radiation.
• the layer of silicone can be hardened by passing the support to which it is applied through thermal ovens whose temperature can vary from 100-220°C, with a residence time in the thermal oven which can range from 2 sec to one minute.
• the coating rate is generally determined by the temperature profile in the ovens and by the length of the ovens.
• the silicone layer In the case of a treatment under radiation energy, the silicone layer is brought into a UV oven or an oven with electronic radiation and it is hardened nearly instantaneously; however, the composition of silicone of the radical or cationic type does not require the presence of a catalyst during exposure to an electronic radiation.
• the flat layer of silicone may have a thickness of 0.4-1.6 ⁇ m, advantageously 0.7-1.2 ⁇ m.
• This silicone layer in general, is applied with a five-roller system for the compositions without solvent and with a system of the type with coating roller and Mayer doctor bar for the compositions with a solvent or aqueous base. Thicker or thinner first layers of silicone may be used if desired.
• the first layer of silicone itself may be built up by application of multiple coats of silicone and that the formulation of each coat may vary, however for ease of manufacture a single coat may be applied.
• the second layer of silicone or three dimensionally microstructured layer of silicone is formed from a composition of silicone comprising one or more polyorganosiloxanes and, advantageously, one or more polydimethylsiloxanes with acrylate and/or epoxy function, and optionally an activation catalyst as a function of need.
• This composition of silicone is without solvent and it is hardened either by exposure to ultraviolet radiation (polydimethylsiloxane with acrylate and/or epoxy function) or by exposure to electronic radiation (polydimethylsiloxane with acrylate function), in which case it does not require the presence of an activation catalyst.
• a suitable UV dose to ensure a correct crosslinking of the silicone is generally greater than 700 mJ/cm 2 .
• composition of silicone comprises one or more polydimethylsiloxanes with acrylate function
• the microstructured layer of silicone is hardened by UV radiation (radical system)
• a ketone photoinitiator advantageously of the benzophenone type, a specific example being 2-hydroxy-2-methyl-1-phenylpropanone.
• an adhesion agent such as polydimethylsiloxane dipropoxylated diglycidyl ether.
• composition of silicone comprises one or more polydimethylsiloxanes with epoxy function
• a photoinitiator of the iodonium type such as diaryliodonium tetrakis (pentafluorophenyl) borate or iodonium hexafluoroantimonate (cationic system).
• the radical systems are preferred over the cationic systems, because they possess a better stability of the anti-adhesive (substrate release) properties over time while, however, requiring the presence of a system for rendering inert with nitrogen during the crosslinking reaction to lower the oxygen level in the gas atmosphere to less than 50 ppm.
• the composition of silicone used to form the second microstructured layer can contain other additives, such as fillers, accelerators, inhibitors, pigments and surfactants.
• the coating of the microstructured layer of silicone is generally carried out using an engraved cylinder. Suitable coating speeds of 10-600 m/min may be used.
• the quantity of silicone (polydimethylsiloxane) will vary as a function of the engraving of the cylinder, the viscosity of the composition, the viscosity of the addition products which can modify the Theological behavior of the layer of silicone, and as a function of the temperature of the silicone. In fact, the silicone is transferred from a roller which is engraved onto the surface of the first layer of silicone to be coated.
• the engraving of the engraved cylinder is filled by immersion into an ink fountain or receptacle containing silicone.
• the excess silicone is generally eliminated by means of a doctor bar.
• a rubber counter roller will be used to ensure the correct transfer of the layer of silicone.
• the engraving of the cylinder will determine the topography of the layer of silicone, that is the desired three-dimensional microstructure.
• the quantity of silicone deposited may be controlled and can vary e.g. from 3 to 25 g/m 2 , advantageously from 4 to 15 g/m 2 .
• the three-dimensional microstructure formed by the combination of the first layer and the second layer of silicone advantageously consists of microstructured units, for example, micro- honeycombed, ridged, or grid shaped motifs, whose crest height can be predetermined.
• crest heights of 3-50 ⁇ m, advantageously 5-25 ⁇ m may be used.
• the engraving used can present the following characteristics: shape: truncated pyramidal, depth (height): 50 ⁇ m, opening: 100 ⁇ m, diagonal measurement of the pyramid: 500 ⁇ m, theoretical volume: 15 cm 3 /m 2 .
• the microstructured layer of silicone which is applied to the flat surface of the first layer of silicone should be crosslinked as rapidly as possible e.g. by UV radiation or electron beam, and thus, in the case of treatment by UV, the UV lamps are positioned preferably as close as possible to the siliconization station (where the second layer is applied to the first layer).
• the power of the UV lamps can range from 120 W/cm to 240 W/cm or more, and it may determine the speed of coating of the microstructured silicone (approximately 100 m/min at 120 W/cm may be acheived).
• a special engraved cylinder so-called "inverse or negative” engraving
• the latter must be deposited first on the support e.g. of paper or plastic, or during a separate coating (presiliconization process), or in tandem, that is on the machine which is in the process of coating the microstructured layer of silicone.
• the coating of the microstructured layer of silicone can also be carried out using a rotating sieve, in which case the silicone is passed through the sieve in contact with the surface to be coated of the first layer.
• the sieve which is used can have the following characteristics: a 30 mesh sieve; thickness of 200 ⁇ m, 15% of opening surface, dimension of the holes of 345 ⁇ m, theoretical volume of the fluid of silicone passing through: 30 cm 3 /m 2 . These parameters are exemplary and may be varied as desired. It is not recommended to crosslink the microstructured layer by the thermal route, because the temperature required for the crosslinking would destroy its three-dimensional structure as a result of flowage even before it can be fixed by crosslinking.
• the surface of the support ideally should have the same surface tension as the silicone which is deposited on it and thus ideally a surface of the same nature as silicone: a siliconated surface. In this case, the silicone which one coats will not tend theoretically to retract or spread.
• the surface tensions of the silicone layers are 19-24 mN/m (or dyne/cm), advantageously 21-23 mN/m.
• the method which is generally used to determine the surface tension is the Owens-Wendt drop method with three components (liquids used: hexadecane, water, giycerol, diiodomethane; measurement temperature: 23°C).
• a layer of silicone which has been treated with heat will have substantially the same surface tension as a silicone layer which has been treated by UV radiation.
• the microstructured layer of silicone can consequently be applied easily to the flat surface of a layer of silicone which has been crosslinked thermally.
• the layers of silicone fulfill a double role; the role of imposing an inverse topography on the surface of a film which will be made in close contact with them and that of an anti-adhesive agent which will facilitate the separation of the film made from the material which was applied to the microstructured silicone.
• any plastic film can be appropriate, for example, cast polyvinyl chloride or a film made of a solvent base, or in the form of an organosol or plastisol.
• Other cast films could also be considered, such as polypropylene, polyurethane, and polyethylene.
• the principal objective of the method of the invention is to confer to the cast film a surface finish by micro-replication, for example, for the visual aspect or for various technical reasons.
• the layer of adhesive in that case, will advantageously be coated directly on the microstructured silicone, or pressed on the silicone by lamination using a lamination device.
• the adhesive will be in liquid form, for example, in solution in an organic solvent or a mixture of organic solvents or in an emulsion in water, or in the form of a solid, that is in the form of an adhesive without solvent which is hot cast on the microstructured silicone.
• the coating process used to coat the adhesive on the silicone must be such that it does not affect the microstructure of the silicone by abrasion, the latter process is preferably carried out using a slit extruder, a coating roller equipped with a scraper or a doctor bar.
• adhesive type one could use any of the adhesives which are applicable in the field considered. In this regard, mention is made of the adhesives based on acrylic, rubber, silicone, and polyurethane. These adhesives can be solvent based, water based, or without solvent, in the molten state.
• the choice of the adhesive will determine the ease of replicating the microstructure of the silicone and the more or less permanent maintenance of its inverse microstructure when the substrate containing the microstructured adhesive is later applied to a given object, such as a display window, painted canvas, or a panel.
• the self adhesive resins which self crosslink when heated are based on an acrylic copolymer dissolved in a mixture of organic solvents
• the self adhesive resins which can be crosslinked by the addition of isocyanate and are based on an acrylic copolymer dissolved in a mixture of organic solvents
• the acrylic copolymers in an aqueous dispersion where the acrylic monomers for this purpose are preferably 2-ethylhexyl acrylate, butyl acrylate and acrylic acid
• the adhesives based on natural and/or synthetic rubber which may or may not be dissolved in a mixture of organic solvents.
• FIG. 1 in the drawing of the appendix represents a slightly enlarged cross-sectional view of a support 1 to which a flat first layer of silicone 2 and microstructured second layer of silicone 3 have been applied, respectively.
• the first and second layers 2 and 3 and support 1 are adhered together to form a unitary three-dimensional microstructure 4.
• This microstructure 4 comprises a plurality of crests or ridges that consist of the microstructured layer 3 fixed to support 1 via the first layer 2.
• first silicone layer 2 and the second silicone layer 3 form a continuous siliconized surface 5 on support 1.
• the siliconized surface 5 has anti-adhesive properties which extend from bottom zones 5a continuously over crest zones 5b to provide a surface adapted to release a substrate in contact therewith.
• the plurality of crests or ridges are preferably distributed evenly over the siliconized surface 2a of the support 1 , and facilitate the separation of a substrate film (see Fig. 7) with or without adhesive which will have been deposited on the microstructured silicone.
• the following tests and examples better illustrate the invention although they in no case limit it. Tests on a pilot installation The materials used, the operating conditions and the results of the tests are given in Tables 1 and 2 below. 1.
• Coating of a "grid" of silicone on presiliconated paper The coating of the microstructured ("grid shaped") layer of silicone is carried out by "inverse" engraving, that is by pyramids on the table of the cylinder. These pyramids may have a truncated shape or be similar to a pyramid having its apex removed in a cylindrical fashion. Characteristics of the engraving (see Figure 2a: plan view of the engraving, and Figure 2b: cross-sectional view along line lib). Cylinder No. 58472 chrome coated Depth: 0.050 mm. Opening: 0.100 mm Diagonal measurement of the pyramid: 0.500 mm. Bottom: 0.015 mm.
• the filling of the engraving is carried out either using a closed chamber equipped with doctor bars, or by immersion of the engraving in the silicone bath, where the excess silicone on the surface of the engraving is then eliminated with a doctor bar (made of steel, nylon or any other material).
• the fixation of the microstructured layer of silicone is carried out using a battery of mercury UV lamps with average pressure and a power of 200 Wm.
• Signback 13 is a sized paper with kaolin of 130 g/m 2 .
• R630GE is a mixture of polyorganosiloxanes with Pt catalyst, without solvent.
• UV902G (+CRA 709) is a mixture of polyorganosiloxanes comprising acrylate functions, and it is placed in the presence of 2-hydroxy-2- methyl-1-phenylpropanone as photoinitiator, from the company Goldschmidt.
• UVPC 900 RP is a mixture of polyorganosiloxanes comprising acrylate functions, and it is placed in the presence of 2-hydroxy-2-methyl ⁇ 1 - phenylpropanone, from the company Rhodia.
• UV 902G is a mixture of polydimethylsiloxanes functionalized with acrylate function and of 2-hydroxy-2-methyl-1 -phenylpropanone from the company Goldschmidt.
• M8129 is a sheet of glossy white PVC having a thickness 90 ⁇ m.
• Figure 3 is a scanning electron micrograph of the microstructured surface of silicone of Example No. 2 according to the invention (magnification X 15 and X 30).
• Figure 4 is a scanning electron micrograph of the microstructured surface of silicone obtained by a known method of the prior art.
• the layer of silicone, deposited on the glossy face of the polyethylene film of a two-faced polyethylenated paper, is microembossed with heating (110°C) and at low speed (0.9 m/min) by an engraved cylinder;
• the counter cylinder is a silicone rubber roller which has a Shore hardness of 85 and is heated at 120°C;
• the pressure exerted between the two cylinders is 22 N/mm 2 .
• the inventive microstructured support has on the surface of the silicone ( Figure 3) very regular features which are rounded at the level of the crests, which prevents or reduces the possility of transfer of the image of the silicone pattern to the surface of the substrate e.g.
• a flexible film of PVC that is there is no alteration in the surface appearance of the substrate film.
• the surface of the substrate PVC film is altered by the microstructures of the polyethylenated and siliconated paper whose embossed crests are much sharper and less rounded; the micro-honeycombed pattern is visible through the PVC film which the crests deform.
• the prior art may use a thicker substrate to lessen or blunt the image transfer.
• preferred embodiments of the present invention use rounded microstructured crests or ridges which lessen or prevent silicone crest pattern transfer through to a substrates distal surface.
• the microstructured support of the present invention may by inverse replication define the topography of the adjacent proximate surface of the substrate while not transferring a visible (to the naked eye) image through to the distal surface of the substrate.
• This means that use of thinner substrates or facestocks may be possible e.g. 60 im, 50im, or 40 1m or less may possibly be used thereby effecting a material cost savings since it is unnecessary to use an added thickness to lessen the visual effect caused by using a patterned silicone liner having sharp crests.
• Other tests and test results are given in Tables 3 and 4 below. 1. Coating of a grid of silicone on presiliconated paper The operating procedure is substantially the same as the one used above. Table 3. Siliconization (with engraved roller and doctor bar)
• R630RP mixture of polyorganosiloxanes without solvent from Rhodia
• RF310RP mixture of polyorganosiloxanes without solvent from Rhodia
• UV902G see Table 1 (viscosity 800 cps, spindle 4, v20).
• UV PC900RP see Table 1
• R625DC / R620DC Silicone system without solvent from Dow Corning.
• UV902G UV free radical crosslinking silicone system from Goldschmidt (viscosity brookfield 800 cps, spindle 4, speed 20 tours/min).
• Resin Solucryl 360 AB (acrylic copolymer); 720 kg Solvent Butyl acetate; 150 kg Crosslinking agent : mixture of 2-pentanedione (1.5 kg), 3-isopropanol (0.8 kg), Ti acetyl acetonate (0.188 kg) and Al acetyl acetonate (2.02 kg). Viscosity : 1300 cps (spindle 4, v20, brookfield).
• Figure 5 is a scanning electron micrograph of the microstructured surface of silicone (top left side) and of an inversely replicated adhesive (bottom right side) obtained according to the method of the invention on industrial application (60 x magnification with a 68°tilt).
• the microstructured crests are very smooth and the conjunction of rounded crests and of relatively small crest depth of about 10 ⁇ m, cooperates to greatly reduce and even prevent the visible transfer of the microstructured silicone pattern to the distal surface of the adhesive coated substrate of the flexible film of PVC.
• crest or ridge depths less than 15 ⁇ m may be used to help lessen or prevent the undesirable visual effect.
• Figure 6 is a scanning electron micrograph of the initial contact topography between the adhesive surface and the surface of the substrate support which receives the self-adhesive film microstructured according to the method of the invention.
• the percentage of initial contact area may be made substantially lower than the values obtained with the microstructured adhesives known to date, which are higher than 35%.
• the contact area is about 25%.
• the percentages of initial contact surface between the adhesive layer and the substrate support may vary and in one preferred embodiment are from 15 to 32%, and preferably of 23 to 28% of the total covering surface.
• this low level of contact surface allows for better repositioning properties of the adhesive film than the adhesive films of the prior art, in conjunction with good adhesion between the surface of the substrate and a supporting object to which it is applied, because the adhesive surface at the top of the crests is substantially planar and will give by microreplication a plane microplateau. Furthermore, the presence of so formed microchannels of small depth (of about 10 ⁇ m) and the high immediate non contact adhesive surface (of about 70% or more) provides to the self- adhesive product a repositionable character in the case of the initial application pressure is low.
• the plane surfaces of the different plateaux of adhesive can extend substantially to the plane valleys of the first layer of silicone depending on the exerted pressure, the viscoelasticity properties of the adhesive, the time and the temperature to coalesce into a uniform and continuous surface (without the original microchannels) in close contact with the application(object).
• Figure 7 is a diagrammatic representation in two dimensions of the process of the invention showing a presiliconised support (1 , 2) on which a microstructured silicone layer 3 has been applied, hardenable by ultraviolet radiation, as well as an inverse replicated three-dimensional microstructure obtained on the adhesive layer 10 of substrate 11when contacting the latter with the presiliconized liner (1 ,2) and the microstructured layer 3, and also a substrate 11 having a facestock 12.
• a presiliconised support (1 , 2) on which a microstructured silicone layer 3 has been applied, hardenable by ultraviolet radiation, as well as an inverse replicated three-dimensional microstructure obtained on the adhesive layer 10 of substrate 11when contacting the latter with the presiliconized liner (1 ,2) and the microstructured layer 3, and also a substrate 11 having a facestock 12.
• the percentage of adhesive surface which will be immediately in contact with the surface on which the self- adhesive film will be applied is 27 %, this percentage being calculated as follows :
• Distance AB 237 ⁇ m
• Distance BC
• the adhesion interface between the adhesive surface and the application surface is substantially planar because it corresponds to the valleys formed by the first flat layer of silicone of the three-dimensional microstructure.
• a microstructured surface of silicone on any type of substrate such as a cellulosic or noncellulosic paper (calendered or glossy, sized), plastic films e.g.
• microstructured adhesive makes it easy to apply, for example, large emblems on given surfaces. Indeed, in general one has to remove and reapply the emblem to position it better and, once it is applied, one often has to eliminate pockets of air caught under the self-adhesive film during the application or pockets of gas which occur sometime after the application.
• the microstructured adhesive according to the present invention allows easy repositioning, easy elimination of bubbles during the application by simply applying manual pressure e.g. with one or more fingers or a hand, and it allows the elimination, through the microchannels formed, of any gas which may have been enclosed after the application.
• inventive articles may be formed according to the present invention including a novel release liner, a novel pressure sensitive adhesive label having a release liner and that such articles may be employed in a wide variety of applications including in the production of very large graphic panels suitable for placement on buildings, vehicles and billboards.
• Such large graphic panels may have a width of 30, 50, 100 or 150 cm or more with a length usually at least as long or often 1 , 2, 3 or many meters more in length.
• Such panels or sheets may often have a thickness of 1.25 millimeters(mm) or less.
• One preferred embodiment of the invention is a multilayer sheet comprising: (a) a flexible support comprising: (i) a sheetlike structure having a first broad surface and opposing second broad surface; (ii) a first layer of a silicone containing material e.g.
• the sheetlike structure of the flexible support is preferably not distorted into a plurality of ridges or crests corresponding to the second layer ridges or crests e.g. by embossing.
• the distal second surface of the flexible substrate is visually free from any ridge or crest pattern corresponding to the plurality of ridges or crests of the flexible support.
• the substrate may comprise a first adhesive layer forming a proximate first surface of the substrate, and may optionally further comprise a first facestock layer in contact with the first adhesive layer and the facestock layer forming an opposing distal second surface of the substrate.
• the distal substrate surface may be printed e.g.
• inks, pigments or colorants with one or more images, indicia or designs or it may be unprinted, transparent, opaque, translucent, black, white or colored, either in part or over its entire surface.
• the distal surface of the substrate may also optionally have an additional exterior protective coating or layer applied thereto.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Laminated Bodies (AREA)
• Adhesive Tapes (AREA)
• Adhesives Or Adhesive Processes (AREA)
• Shaping Of Tube Ends By Bending Or Straightening (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Manufacturing Of Printed Wiring (AREA)
• Diaphragms For Electromechanical Transducers (AREA)

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