Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/40—Distributing applied liquids or other fluent materials by members moving relatively to surface
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C9/00—Apparatus or plant for applying liquid or other fluent material to surfaces by means not covered by any preceding group, or in which the means of applying the liquid or other fluent material is not important
  • B05C9/08—Apparatus or plant for applying liquid or other fluent material to surfaces by means not covered by any preceding group, or in which the means of applying the liquid or other fluent material is not important for applying liquid or other fluent material and performing an auxiliary operation
  • B05C9/12—Apparatus or plant for applying liquid or other fluent material to surfaces by means not covered by any preceding group, or in which the means of applying the liquid or other fluent material is not important for applying liquid or other fluent material and performing an auxiliary operation the auxiliary operation being performed after the application
• • 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
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/22—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of indefinite length
  • B29C43/222—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of indefinite length characterised by the shape of the surface
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D2201/00—Polymeric substrate or laminate
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D2252/00—Sheets
  • B05D2252/02—Sheets of indefinite length
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
  • B05D3/06—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to radiation
  • B05D3/061—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to radiation using U.V.
  • B05D3/065—After-treatment
  • B05D3/067—Curing or cross-linking the coating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
  • B05D3/06—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to radiation
  • B05D3/068—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by exposure to radiation using ionising radiations (gamma, X, electrons)

Definitions

• This invention relates to an apparatus and method for laminating flat substrates. More particularly, the invention relates to an apparatus and method for applying laminar radiation-cured polymeric coatings to thermo ⁇ plastic sheet and film.
• Thermoplastic substrates such as polycarbonate sheet and film, often are coated with polymeric coatings.
• These coatings have various protective and decorative purposes, such as imparting abrasion and chemical resistance, removing or masking surface imperfections, and providing a specialty surface.
• Such specialty surfaces range from glossy, smooth surfaces to matte or textured surfaces.
• a textured surface coating were desired, it usually would be formed by impressing and thermoforming the cured surfaces with a heated roller or calendar. This procedure can only be used with coated surfaces which have at least some thermoplastic character. Many of the so-called
• hardcoats used to protect thermoplastics against abrasions, are highly cross-linked thermoset resins. Attempts to texture the surfaces of these coatings by thermoforming often results in rupture or separation of the coating, as it does not have adequate elongation characteristics.
• the radiation-curable acrylic coatings are typically viscous liquids prior to curing. therefore, it is difficult to maintain the dimensional stability of the coating when the surface texture is formed prior to curing.
• thermoplastic sheets and film A need exists for an efficient procedure for applying surface-textured, hard, abrasion and chemical resistant coatings to thermoplastic sheets and film.
• the laminar impressor of this invention permits the application of a very uniform thickness of a surface coating to a flat substrate, such as a thermoplastic sheet or film.
• a flat substrate such as a thermoplastic sheet or film.
• the apparatus is useful for accurately and efficiently forming a wide variety of surface textures to the coatings.
• the apparatus is particularly suited to large scale automated coating operations.
• Figure 1 is a schematic diagram of a laminar impressor according to the present invention, which employs an endless impressor belt.
• Figure 2 is a schematic diagram of a laminar impressor according to the present invention, wherein the impressor belt is stripped from the coating for reuse or discard.
• Figure 3 is a schematic diagram of a laminar impressor according to the present invention, wherein the impressor belt is left on the cured coating as a masking film, for subsequent removal by the user.
• the laminar impressor of this invention employs a non-adhering impressor belt for impressing a desired surface texture into an uncured coating.
• the coating is radiation-cured while the impressor belt is still in contact with the coating, thereby insuring that the surface texture of the belt is faithfully transferred to the coating.
• the impressor belt may be fabricated from a wide variety of materials.
• the belt is non-adhering, which, as used herein, means that the impressor belt can be stripped from the cured coating without removing the coating from the coated substrate.
• the impressor belt is constructed from a material which can be formed with the desired surface texture, and has sufficient surface resiliency that the texture will be transferred to the uncured coating composition.
• polymeric films such as polyester and polyolefin films
• polyester and polyolefin films have been found to be well-suited for the construction of impressor belts. These films can be embossed with a wide variety of surface textures, using a heated metal roller. Polyester and polyolefin films having leather and fabric textures, matte surfaces, smooth glossy surfaces, and many others are presently available commercially.
• Non-polymeric materials such as thin-gauge metal, can also be used.
• the term "texture" incudes surfaces ranging from glossy to highly formed. By employing a surface treatment or a release coating, materials that might otherwise adhere to the cured coating may be used.
• the coating is cured by irradiating it through the impressor belt. Therefore, the impressor belt preferably is transparent to the radiation used for curing the coating. Such coatings are typically cured with ultraviolet (“UV” ) light or electron beam (“EB”) radiation. Polyester and polyolefin films are highly transparent to ultraviolet radiation, which is another reason for preferring these materials for the construction of the impressor belts. A wide range of materials can be used with EB radiation, since the degree of transparency to EB is related only to the mass of the material.
• UV ultraviolet
• EB electron beam
• compositions used for coating the substrates may be any of the well-known, radiation-curable polymeric coatings. Such coatings usually are based on acrylic resin systems, although other polymer systems are also used. One example of such a coating composition is described by James E. Moore, et al. in U.S. patent 4,107,391.
• the coating advantageously has a viscosity in the uncured state such that it readily flows into the cavities and depressions of the impressor belt.
• the viscosity is preferably great enough to support the impressor belt and prevent flow-out of the coating composition prior to cure.
• Virtually any flat substrate can be coated using the laminar impressor of this invention.
• Such substrates include thermoplastic substrates, metallic sheets, plywood, particle board, and certain fabrics, to name but a few.
• Preferred substrates include thermoplastic sheets and films.
• Decorative and protective coatings for these materials greatly increase the scope of their application.
• Particularly preferred substrates are polycarbonate sheets and films.
• the laminar impressor of this invention may take a variety of configurations. Referring to the drawings.
• Figure 1 shows an embodiment of the invention which employs an endless laminar impressor belt.
• the apparatus has a conveyer (not shown) for conveying a flat substrate 14 in a horizontal direction.
• Nip roll 15 is positioned above the surface of the flat substrate, and provids a controlled gap for the coating composition.
• Nip roll 15 is usually surfaced with a resilient material, such as rubber, and the thickness of the gap for the coating composition is controlled by the pressure of the nip roll against the substrate and the viscosity of the coating composition.
• Nip roll 15 is cylindrical and rotates in the direction of, and at substantially the same speed as, the movement of the flat substrate 14. Impressor belt 10 is fed between nip roll 15 and flat substrate 14.
• Idler rollers 13 and 17 feed the impressor belt 10 to nip roll ⁇ 15 and bias the impressor belt against the nip roll such that it remains in contact with the nip roll.
• the biasing tension can be maintained with springs or belt tensioners (not shown) on idler rollers 13 or 17.
• the gap between nip roll 15 and the surface of the flat substrate 14 will depend upon the speed of the flat substrate, the viscosity of the coating , which is also related to the temperature, and the pressure of the nip roll.
• the gap ranges from about 0.001 to about 0.08 mm, preferably from about 0.0025 to about 0.025 mm.
• Uncured coating composition 23 is applied to the surface of the flat substrate or to the surface of impressor belt 10 upstream from nip roll 15.
• the coating is uniformly applied, using a die coater 21 or similar device.
• the rate of application is controlled to supply adequate coating for a continuous lamination without causing undue build-up at the nip roll.
• the coating Downstream from the nip roll 15, the coating is uniformly sandwiched between the surface of the flat substrate and the impressor belt. At this point, the coating is irradiated with a polymerization-initiating radiation.
• a UV lamp or electron beam radiator 19 is preferably positioned above the moving laminated substrate, and radiation is directed into the coating. The intensity and duration of the radiation are controlled to cure the coating to a solid state, which maintains its surface texture after removal of the impressor belt 10.
• the radiation device 19 directs radiation through the impressor belt.
• the impressor belt is substantially transparent to the radiation.
• the radiation device 19 may be positioned below the flat substrate, with the radiation directed through the flat substrate into the coating. This embodiment may be used when the flat substrate is transparent to the radiation.
• radiation devices may be positioned on each side of the flat substrate.
• the impressor belt may be removed from the coating.
• the impressor belt is removed using a stripper roll 16 and a take-up roll 12.
• the endless impressor belt 10 is then recycled to idler rollers 17 and 13 for reuse.
• the cured coating 24 is firmly adhered to the flat substrate, and the surface texture of the impressor belt is faithfully transferred to the coating.
• the impressor belt 10 is fed from feed roll 26 to idler roller 13.
• Feed roll 26 contains an adequate length of impressor belt 10 for a production run.
• stripper roll 16 removes impressor belt 10 from the cured coating 24.
• the removed impressor belt can be stored on a take-up roll (not shown) for reuse or discard.
• Figure 3 impressor belt 10 is left on the cured coating 24 as a masking film. The impressor belt thus protects the coated surface during subsequent handling and transportation of the product, and can be removed by the user at the point of application.
• any of the embodiments shown in Figures 1, 2 and 3 can be adapted for simultaneous two- sided coatings.
• Such two-sided coating can be achieved by placing a laminar impressor apparatus on each side of the moving flat substrate.
• the laminar impressor of this invention is well- suited to large-scale automated operations. Conveyer speeds ranging from about 5 ft./min. to about 500 ft./min., preferably from about 15 ft./min. to about 50 ft./min. may be used.

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• 1989
  • 1989-06-12 EP EP19890911326 patent/EP0428628A1/de not_active Withdrawn
  • 1989-06-12 JP JP51054089A patent/JPH03503138A/ja active Pending
  • 1989-06-12 WO PCT/US1989/002541 patent/WO1990015673A1/en not_active Application Discontinuation

Non-Patent Citations (1)

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